EQUIPMENT FOR DRY POLISHING AND GRINDING OPERATIONS

TECHNICAL FIELD

[0001]The present disclosure relates to concrete surface processing equipment, and in particular to power trowels and floor grinders suitable for dry polishing operations involving fine grit grinding tools and also dry grinding operations involving more coarse grit grinding tools.

BACKGROUND

[0002]A power trowel, sometimes also referred to as a power float, is a machine used to process larger concrete surfaces. The power trowel can be used on semi-matured concrete to even out the surface after pouring. A power trowel can also be used on dry concrete surfaces to order to even it out and to obtain a desired finish if the trowel tools are replaced by grinding tools.

[0003]A power trowel comprises one or more rotatable sets of tool holders which may hold trowel tools or grinding tools. Larger power trowels with two or more sets of rotatable tool holders are often ride-on versions where the operator sits on top of the trowel, while smaller power trowels with a single set of rotating tool holders are normally manually guided by an operator walking next to the power trowel.

[0004]A floor grinder is a machine used to grind hard surfaces such as concrete surfaces, e.g., in order to even out the surface or to remove an upper part of the surface.

[0005]Power trowels and floor grinders may be referred to collectively as surface processing equipment.

[0006]There is a desire to provide improved surface processing equipment such as power trowels and floor grinders, and in particular power trowels and floor grinders suitable for dry polishing and dry grinding operations.

SUMMARY

[0007]It is an object of the present disclosure to provide surface processing equipment such as power trowels and floor grinders suitable for dry polishing and for dry grinding operations. Some of the equipment described herein is also suitable for wet grinding and polishing operations. This object is at least in part obtained by surface processing equipment comprising one or more sets of rotatable tool holders for processing a concrete surface. The equipment comprises a protective cage structure arranged to enclose the sets of tool holders. The equipment is arranged to cooperate with a dust extraction system arranged to draw a particle-laden airflow out from an interior of the protective cage structure via at least one aperture formed in the protective cage structure. The dust extraction system may be an on-board dust extraction system arranged integrated with the equipment, or a dust extraction system arranged external to the equipment. The dust extraction system may be arranged to communicate with a control unit of the surface processing equipment, e.g., by wireless or wired link. The dust extraction system that the equipment is arranged to cooperate with is arranged to capture dust particles in the particle-laden airflow, e.g., by a filter and/or cyclone arrangement. Thus, the potentially harmful dust generated during dry polishing and dry grinding operations by the equipment is captured by the dust extraction system before it can do harm to personnel at the work site. At least one further aperture is preferably arranged in the protective cage structure to allow an amount of air to enter into the interior of the protective cage structure. This way the air pressure in the interior of the protective cage structure is controlled, which improves air flow out from the interior of the protective cage structure. This is because a low air pressure in the interior of the protective cage structure is detrimental to air flow out from the interior. The dust extraction system can be integrated efficiently in the equipment and powered by the same power source as the troweling or grinding tools, which is an advantage. A control unit on the equipment can be used to automate activation and deactivation of the dust extraction system, e.g., in dependence of an operating state of the equipment (such as if the trowel or grinding tools are operating), or in dependence of a measured dust concentration level. The presence of water inside the protective cage structure can also be detected and the absence of water used as criteria for activating the dust extraction system.

[0008]An aperture formed in the protective cage structure that is used to draw at least a part of the particle-laden airflow out from the interior of the protective cage structure can be referred to as an inlet aperture of the dust extraction system. There may be one or more such inlet apertures formed in the protective cage structure.

[0009]An aperture formed in the protective cage structure that is used to allow an amount of air, preferably a controlled amount of air, to enter into the interior of the protective cage structure can be referred to as a ventilation aperture of the dust extraction system.

[0010]It is appreciated that an aperture formed in the protective cage structure can be used either as an inlet aperture or as a ventilation aperture.

[0011]According to some aspects, the control unit also controls a speed of the dust extraction blower or fan comprised in the dust extraction system that the equipment is arranged to cooperate with, in dependence of the operating conditions of the equipment. An operating power level of the dust extraction system can thus be controlled based, e.g., on an amount of dust generated by the tools, on an air pressure in the interior of the protective cage structure, and/or based on a magnitude of the air flow of the particle-laden airflow drawn out from the interior of the protective cage structure.

[0012]The dust extraction system is preferably an on-board dust extraction system arranged in a position vertically overlapping the protective cage structure, i.e., on top of the protective cage structure. This means that only a very short air conduit, or no air conduit is necessary between the interior of the protective cage structure and the dust extraction system, which is an advantage. In fact, the dust extraction system can be connected directly to the aperture formed in the protective cage structure via a rigid tube, thereby avoiding long dust extraction system hoses that can get in the way and cause problems at the work site.

[0013]The surface processing equipment preferably comprises an outer skirt arranged around the one or more sets of rotatable tool holders to seal a volume against the concrete surface. At least one aperture of the dust extraction system is arranged in the volume to draw the particle-laden airflow out from the volume where dust is being generated. The outer skirt improves the efficiency of the dust extraction system. Dust generated during dry polishing or dry grinding is prevented from entering into the ambient environment by the outer skirt, which is an advantage. The particle laden air trapped by the outer skirt is drawn out from the volume and filtered before being released into the ambient environment or led back into the volume. The skirt also contributes to generating air turbulence that disturbs the dust inside the protective cage structure such that it can be more easily extracted via the at least one aperture. An inner skirt is optionally arranged offset from the outer skirt to define a slot between the outer skirt and the inner skirt. The volume delimited by the inner and outer skirts promotes air flow to increase the efficiency of the dust extraction system. The part of the slot facing the concrete surface functions as a dust extractor nozzle which vacuums the concrete surface as the equipment moves over the surface, thereby capturing potentially harmful dust particles in an efficient manner. The protective cage structure preferably comprises a sealed upper surface which prevents dust from escaping upwards and into the ambient environment.

[0014]According to some aspects a gap is formed between the concrete surface and the inner skirt, i.e., the inner skirt does not extend all the way down to the concrete surface. This allows dust to pass the inner skirt and into the space between the inner skirt and the outer skirt.

[0015]The gap formed between the skirts and the surface and/or the gap formed between the inner and outer skirts, can also be adjusted in order to enhance the dust extraction. A smaller gap generally results in higher air speed, and the higher the air speed the more efficient the dust extraction operation normally is. By adjusting the gap between the skirts and the surface the pressure inside the protective cage structure can be controlled to optimize the dust extraction efficiency. The optimization may be performed by practical experimentation in at a test site and/or by computer simulation.

[0016]According to some aspects, a plurality of apertures are formed in the protective cage structure. By distributing more than one aperture over the interior of the protective cage structure an improved particle capturing by the dust extraction is obtained. One or more of these apertures can be used as inlet apertures of the dust extraction system to draw the particle-laden airflow from the interior of the protective cage structure, and one or more of these apertures can be used as ventilation apertures to allow an amount of air to enter into the interior of the protective cage structure.

[0017]The apertures used to draw the particle-laden airflow out from the cage structure are preferably located around the perimeter of the protective cage structure, since the dust particles are pushed radially outwards from the rotation centers of the sets of tool holders due to centrifugal forces, similar to the workings of a cyclone separator system. This configuration of inlet apertures is particularly effective if the tool holders comprise vanes, as will be discussed in more detail below.

[0018]A dust guide structure can also be arranged in the volume to guide the particle-laden airflow to an aperture of the dust extraction system. This dust guide structure can be configured to concentrate a rotating air flow and guide the air flow towards and into the aperture of the dust extraction system used to draw the particle-laden airflow out from the cage structure, thereby increasing the dust capturing performance of the on-board dust extraction system. The dust guide structure may also be designed so as to increase an air flow speed into the at least one aperture, which improves the dust extraction performance of the system.

[0019]It is easier to capture airborne dust particles compared to dust particles adhered to the concrete surface, therefore, at least one set of the rotatable tool holders optionally comprises a brush configured to rotatably engage the concrete surface in use. The brush may comprise bristles in nylon or other suitable material which brushes against the concrete surface as the grinding tools rotate in use. Rubber or plastic elements can be used as an alternative to bristles or in combination with the bristles. The brush disturbs any dust adhered to the concrete surface, making it airborne and more easily captured by the dust extraction system.

[0020]The surface processing equipment may also comprise a control unit arranged to receive data from a dust sensor arrangement indicative of a dust concentration in an ambient environment of the equipment and to generate a notification or alarm signal in case the dust concentration does not satisfy a dust concentration acceptance criterion. Thus, an operator of the equipment or person at the work site of the equipment is made aware of the high dust concentration and can take suitable action. The dust sensor arrangement can be arranged in connection to an operator control seat, such that it measures the dust concentration in immediate vicinity of the operator. This provides a dust concentration of higher relevance, since it is the dust concentration close to the operator that is most interesting when assessing the risk for harm to the operator from the dust.

[0021]The control unit is optionally arranged to receive data from a pressure sensor arrangement indicative of a pressure difference between an interior of the protective cage structure and ambient environment of the equipment and to generate a notification or alarm signal in case the pressure difference does not satisfy a pressure difference acceptance criterion. The pressure difference signal can be used as indication that the dust extraction system is operating correctly. In case the pressure difference does not satisfy the pressure difference acceptance criterion, then something is most likely wrong, and action needs to be taken in order to protect personnel at the work site from being subjected to harmful dust particles. The pressure sensor arrangement may be a differential pressure sensor arrangement that measures the difference between the interior of the protective cage structure and the ambient environment directly, or an absolute pressure sensor arrangement which measures pressure relative to some reference pressure.

[0022]The control unit can also be arranged to receive data from a water sensor, or from water activation means of the equipment, indicative of the presence of water in the interior of the protective cage structure in addition to the pressure sensor data, and to generate a notification or alarm signal in case the pressure difference does not satisfy a pressure difference acceptance criterion while no water presence is indicated by the water sensor data. This way the control unit is able to detect when a dry polishing or a dry grinding operation is being performed based on the presence or absence of water and ensure that the dust extraction system is operational during dry polishing and dry grinding, or when the water supply for a wet grinding has malfunctioned.

[0023]The surface processing equipment optionally comprises a mounting bracket for holding a water tank or an air cleaner. This dual purpose bracket is adapted to receive either a water tank or an air cleaner, since the two are not needed in combination. The interfaces for the water tank, i.e., water connections leading to water nozzles under the protective cage, and the interfaces for the air cleaner, i.e., air conduits leading to the one or more apertures, can be arranged in connection to the mounting bracket, such that a switch from water tank to air cleaner, and vice versa, can be performed in a convenient manner.

[0024]The on-board air cleaner preferably comprises an air outlet directed at an expected location of an operator of the equipment. This way the air in vicinity of the operator is predominantly filtered air, which means that the operator of the equipment is subjected to a lower concentration of potentially harmful dust particles.

[0025]According to some aspects, the equipment comprises a pressurized air system arranged to provide a pressurized flow of air in the interior of the protective cage structure. The pressurized flow of air may, e.g., be directed via one or more nozzles at the concrete surface in order to disturb dust adhered to the concrete surface. This improves the efficiency of the dust extraction system of the equipment, since airborne dust is more easily extracted compared to dust adhered to the surface. The pressurized air can also be directed at the inside of the protective cage structure, at the equipment chassis, and at the skirt in order to prevent dust from accumulating inside the protective cage structure.

[0026]Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the element, apparatus, component, means, step, etc.” are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. The skilled person realizes that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027]The present disclosure will now be described in more detail with reference to the appended drawings, where

[0028]FIGS. 1A-B illustrates an example power trowel;

[0029]FIG. 2 schematically shows a power trowel with inner and outer skirts;

[0030]FIG. 3 illustrates a power trowel with cage-internal dust guides;

[0031]FIG. 4 illustrates another example power trowel;

[0032]FIG. 5 schematically shows a power trowel with inner and outer skirts;

[0033]FIG. 6 illustrates an example power trowel with cage-internal dust guides;

[0034]FIG. 7A shows a set of rotatable tool holders;

[0035]FIG. 7B schematically illustrates a drive shaft with tool holders;

[0036]FIG. 8 illustrates an example air cleaner;

[0037]FIG. 9 shows an example control unit;

[0038]FIGS. 10, 11, 12A-B show example inner and outer skirts on a power trowel;

[0039]FIG. 13 illustrates example rotatable tool holders comprising vanes; and

[0040]FIGS. 14-17 illustrate details of an example power trowel.

DETAILED DESCRIPTION

[0041]The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain aspects of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments and aspects set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout the description.

[0042]It is to be understood that the present invention is not limited to the embodiments described herein and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

[0043]FIG. 1 illustrates an example ride-on power trowel 100 while FIG. 4 illustrates an example walk-beside power trowel 400. This disclosure is not limited to any particular form of power trowel. Rather, many of the teachings herein are applicable to most power trowel designs, including single-trowel set and multi-trowel set machines, manually and autonomously guided machines, as well as walk-beside and ride-on machines.

[0044]The dimensions indicated in FIG. 1 are given in centimeters with corresponding measurements in inches provided within brackets. The dimensions are to be understood as example dimensions, and not to be seen as limiting the disclosure.

[0045]The various features and functions disclosed herein are applicable in power trowels of the type illustrated in FIGS. 1A-B, and also in floor grinders. Thus, it is appreciated that although the techniques are exemplified by power trowels, the teachings are not limited to power trowels but can also be used in floor grinders. Power trowels and floor grinders are part of a more general class of equipment referred to as surface processing equipment. Surface processing equipment is commonly used when processing hard material surfaces such as concrete surfaces and stone surfaces.

[0046]The example surface processing equipment 100 in FIG. 1 is a ride-on power trowel which comprises an operator seat 150 and two sets of rotatable tool holders 110, arranged side-by-side, while the example surface processing equipment 400 in FIG. 4 is a walk-beside power trowel with a single set of rotatable tool holders 110. The tool holders 110 hold respective trowel tools or grinding tools that engage the concrete surface to be processed. Thus, it is appreciated that the phrase power “trowel” is used broadly herein and encompasses both concrete surface trowelling and grinding. The power trowels and floor grinders discussed herein may be referred to as concrete surface processing equipment or concrete surface processing machines. Some power trowels may not even be capable of holding trowel tools, only grinding tools such as rigid abrasive tools or soft pads comprising polishing compound or abrasive particulate matter.

[0047]A protective cage structure 120 is arranged to enclose the rotatable set or sets of tool holders 110, to protect external objects and personnel, and also to protect the trowel tools or grinding tools during operation. The protective cage 120 may be formed from metal bars or pipes as in FIG. 1 and FIG. 4. Sections of plastic or metal sheet may also form part of the protective cage 120. In a preferred embodiment the protective cage 120 is covered by sheet material which seals an interior of the protective cage structure against the concrete surface from the ambient environment. An outer skirt may be arranged along the bottom perimeter of this sealed protective cage structure to seal against the concrete surface.

[0048]The power trowels 100, 400 comprise optional control units 140 which control various functions of the power trowel, e.g., by obtaining measurements from various sensors arranged in connection to the power trowel. The control unit 140 may be arranged to output control signals to various actuators and user interfaces of the power trowel. An example realization of the control unit 140 will be discussed in more detail below in connection to FIG. 9.

[0049]Each tool holder 110 can be fitted with a trowel tool to smoothen a nearly matured concrete surface, or a grinding tool which grinds or polishes the concrete surface by abrasive action. The grinding tool may comprise rigid abrasive segments, or soft pads with some form of polishing compound or abrasive particles. The grit level of the grinding tools determine the end finish of the concrete surface. An increasing grit size means finer grit, and a grit size of about 800 or more gives a glossy finish. Soft polishing tools are also conceivable, such as pads with polishing paste. More coarse grinding tools can also be used, e.g., if it is desired to level a concrete surface or remove an upper layer of material from a concrete surface. Hence, the power trowel 100 can be used for troweling, grinding, and polishing a concrete surface. The tool holders 110 are arranged in sets around a central rotating axle. During operation the tool holders 110 are rotated in a direction of rotation R as indicated in the Figures. If two tool holders are used, then it may be preferred to arrange the tool holders so as to rotate in opposite directions, i.e., in a counter-rotating configuration.

[0050]A grinding or polishing operation may be conducted as a wet operation, in which case a liquid such as water is added to the contact area between grinding tools and the concrete surface, or as a dry operation in which case no water is used. The water may be obtained from an on-board water tank or from a hose to an external source of water. The control unit 140 may be configured to control the supply of water during grinding or polishing. The operator is often able to activate and deactivate the supply of water using water activation means, i.e., a switch or button that controls a water pump or valve arrangement on the power trowel. A dust extraction system arranged to draw air out from the interior of the protective cage structure 120 may optionally be activated in dependence of the state of the supply of water. It may, for instance, not be desired to activate the dust extraction system when water is applied. Unless the dust extraction system is arranged to extract slurry from the concrete surface.

[0051]Very fine grit can be used during dry polishing (processing in the absence of water) in case a polished surface with high gloss level is desired. However, the small dust particles released during this type of dry polishing operation may be harmful to the operator of the power trowel and to personnel located in the general area. It may be challenging to capture a sufficient amount of such small dust particles using external air cleaners.

[0052]Dry grinding operations, where less fine grit tools are used to process a concrete surface, also releases dust into the ambient environment.

[0053]To improve the work environment for personnel at the work site during an ongoing dry polishing or dry grinding operation, it has been realized that a dust extraction system 130 such as an air cleaner or dust extractor can be fitted onto the power trowel 100, 400 to draw a particle-laden airflow out from an interior of the protective cage structure and filter the air flow, thereby capturing dust particles in the particle-laden airflow. The dust extraction system 130 can be powered by the same main power source as the power trowel or by a separate power source. Any of an on-board electric storage device, a cable to electric mains, a combustion engine, or a hydraulic motor can be used to power the dust extraction system 130.

[0054]The dust extraction system can also be a dust extractor arranged separately from the surface processing equipment 100, 400. Generally, the surface processing equipment disclosed herein is arranged to cooperate with a dust extraction system arranged as an on-board dust extraction system or as a dust extraction system external to the surface processing equipment.

[0055]The surface processing equipment discussed herein is generally arranged to cooperate with one or more dust extraction systems. This means that the equipment may be connected to one or more dust extractors in order to extract a particle-laden air flow from the interior of the protective cage structure 120. This may also mean that the control unit of the surface processing equipment is arranged to communicate with the dust extraction system, and possibly also to control one or more operations of the dust extraction system.

[0056]The dust extraction system is preferably combined with a skirt (not shown in FIG. 1 nor in FIG. 4) arranged to at least partly seal a volume enclosing the set or sets of tool holders 110 against the concrete surface. The skirt may be formed as a sheet attached to the protective cage structure 120 to cover the sets of rotatable tool holders, thereby more efficiently preventing dust generated during the dry polishing or dry grinding operation to escape into the ambient environment. A lower part of the skirt may be loosely connected to the main skirt body in order to move vertically to seal better against the concrete surface. This lower part may also comprise a brush structure, rubber flange, or the like to improve the seal against the concrete surface. The skirt may be formed in various materials, such as metal, plastic, canvas, polyester, nylon, polypropylene, or polyethylene. The skirt may be non air-permeable (not allowing air to pass) or semi air-permeable (allowing a small amount of air to pass), such as a fine mesh.

[0057]To summarize, there is disclosed herein a power trowel 100, 400 such as the example machines in FIG. 1 and in FIG. 4, comprising one or more sets of rotatable tool holders 110 for processing a concrete surface. The power trowel 100, 400 also comprises a protective cage structure 120 arranged to enclose the sets of tool holders 110. The power trowel 100, 400 furthermore comprises an on-board or external dust extraction system 130 arranged to draw a particle-laden airflow A from an interior of the protective cage structure 120 via at least one aperture 250 of the dust extraction system 130, and to capture dust particles in the particle-laden airflow A, e.g., by one or more cyclones and/or filters. This way potentially harmful particulate matter released during, e.g., concrete surface polishing, is captured by the dust extraction system before it is released into the ambient environment. The dust extraction system 130 may comprise, e.g., an air cleaner 800 as illustrated in FIG. 8 or a dust extractor. The dust extraction system 130 preferably comprises an essential filter, e.g., a High-Efficiency Particulate Air (HEPA) filter, but other air filters may also be used. HEPA, also known as high-efficiency particulate absorbing and high-efficiency particulate arrestance, is an efficiency standard of air filters. Filters meeting the HEPA standard must satisfy certain levels of efficiency. Both air cleaners and dust extractors are known in the art and will therefore not be discussed in more detail herein.

[0058]The air pressure inside the protective cage structure 120 normally falls when the dust extraction system draws the particle laden air out from the interior of the protective cage structure 120. This drop in air pressure may hamper the air flow out through the aperture used to extract the particle laden air, resulting in a reduced air flow and a decreased dust extraction performance. To improve air flow, at least one further aperture can be arranged in the protective cage structure to allow an amount of air to enter into the interior of the protective cage structure. This creates a flow of air into the cage structure, which then helps draw the particle laden air out from the cage structure.

[0059]It is appreciated that an aperture formed in the protective cage structure that is used to draw at least a part of the particle-laden airflow out from the interior of the protective cage structure can be referred to as an inlet aperture of the dust extraction system. There may be one or more such inlet apertures formed in the protective cage structure. An aperture formed in the protective cage structure that is used to allow an amount of air, preferably a controlled amount of air, to enter into the interior of the protective cage structure can be referred to as a ventilation aperture of the dust extraction system. It is appreciated that most apertures formed in the protective cage structure can be used as either inlet aperture or ventilation aperture.

[0060]According to some aspects one or more of the apertures formed in the protective cage structure are adjustable in size, such that an operator or technician can adjust the size of the aperture to control the air flow in or out through the aperture. This type of adjustable aperture may be useful if it is desired to optimize the air pressure in the interior of the protective cage structure, or the air flow through the interior of the protective cage structure.

[0061]According to some aspects of the disclosure the power trowel 100, 400 and/or the dust extraction system 130 is at least partly powered by a combustion engine that generates exhaust in use. It may be undesired to release this exhaust into the ambient environment. The exhaust from the combustion engine can therefore advantageously be guided via a conduit from the combustion engine to the at least one further aperture 250 used as inlet for air into the interior of the protective cage structure. The exhaust gasses are then drawn out from the cage structure and filtered by the dust extraction system before being released into the ambient environment. This way efficient exhaust filtering may be provided in an efficient manner.

[0062]The on-board dust extraction system 130 is preferably arranged in a position vertically overlapping the protective cage structure 120, i.e., on top of the cage structure, overlapping when viewed from a vertical direction. This is an advantageous position since only a very short air conduit from the dust extraction system to the interior of the cage is needed, or no air conduit at all, if the dust extraction system has an aperture opening up in the protective cage structure. The position on top of the cage structure, overlapping when viewed from a vertical direction, also means that the footprint of the machine 100 does not increase, which is an advantage since it allows the machine to more easily reach difficult locations on the concrete surface to be processed.

[0063]The control unit 140 may be configured to control the operation of the dust extraction system 130, e.g., to activate it when the power trowel is started. The control unit 140 may also control a power of a fan motor of the dust extraction system in dependence of an amount of dust generated by the power trowel, such that an increased air flow is generated when significant dust is generated. The amount of dust generated may be measured by a dust sensor arrangement connected to the control unit 140.

[0064]According to some aspects, the control unit 140 is arranged to detect presence of a grinding tool and/or a trowel tool attached to one or more of the tool holders 110, and to activate the dust extraction system 130 based on the presence or absence of the grinding tool. Detection of presence or absence can be implemented, e.g., by radio frequency identification (RFID) readers on the power trowel configured to read RFID tags attached to the different tools, or by geometrical solutions that key in to dedicated switches arranged on the tool holders. I.e., a trowel tool may be configured to flip one switch and a grinding tool to flip another switch, while a polishing pad is configured to flip a third switch. This way the dust extraction system is only activated when needed, i.e., when dry polishing or dry grinding tools are in use, and not when wet operations are performed by the power trowel.

[0065]According to other aspects, the control unit 140 is arranged to receive data from a water sensor and/or or from water activation means as discussed above, which data is indicative of the presence of water in the interior of the protective cage structure 120. The control unit 140 may then activate the dust extraction system 130 based on the presence or absence of water inside the protective cage. It may be desired to use the dust extraction system only when dry polishing or dry grinding operations are being performed, and not when water is present in the interior of the protective cage structure.

[0066]FIGS. 2, 3, 5, and 6 schematically illustrate different arrangements for increasing the efficiency of the dust capturing by the dust extraction system 130. The rotation of the tool holders 110 is illustrated in the Figures by the arrows R. This rotation generates a cyclone-like air stream in the protective cage interior, due to that the particle laden air flow A is brought into rotation by the tool holders 110. The one or more inlet apertures 250 of the dust extraction system 130 are therefore preferably arranged close to the cage structure, radially outwards from the rotation center or centers of the sets of rotatable tool holders 110. One or more further apertures 250 may as noted above be used as ventilation apertures in order to regulate the air pressure in the interior of the protective cage structure. This is indicated in FIG. 2 by the example air flow directional arrows, where flow into the interior of the cage structure is indicated by dashed arrows and flow out from the interior of the cage structure is indicated by solid arrows.

[0067]The power trowel 100, 400 preferably comprises an outer skirt 240 arranged around the one or more sets of rotatable tool holders 110 and to seal a volume 201 against the concrete surface, e.g., by an optional vertically extending moving member resting on the concrete surface in use. At least one aperture 250 of the dust extraction system 130 is arranged in the volume 201 as illustrated in the Figures. There may be one or more apertures 250, where at least one aperture is connected to a low pressure section of the dust extraction system 130 to extract an air flow from the volume 201. One or more further apertures may be arranged as ventilation apertures to regulate the air pressure inside the interior of the protective cage structure in order to improve the air flow out from the interior of the protective cage structure 120.

[0068]FIGS. 2 and 3 show examples 200, 300 where the outer skirt 240 is arranged around two sets of rotating power tool holders. The two power tool holders 110 are preferably counter-rotating, which means that the directions of rotations of the two tool holders are opposite to each other. The outer limits of the rotating tools are shown as dashed lines 210, 220, and the outer skirt 240 is arranged to follow these contours at a distance of a couple of centimeters, such as 5-10 centimeters. A plurality of apertures 250 are arranged in an interior of the protective cage structure 120, and inside the skirts 240 in FIG. 2 and FIG. 3. Any number of apertures 250 can be used. At least one aperture is connected to the dust extraction system 130, such that the particle-laden airflow A is drawn out from the interior of the skirt-enclosed volume and into the dust extraction system, where the air flow is filtered to capture dust particles in the particle-laden airflow. One or more further apertures 250 may be configured as ventilation apertures in order to regulate the air pressure inside the interior of the protective cage structure by allowing an amount of air to enter into the interior of the protective cage structure.

[0069]The connections between the one or more apertures 250 used as inlet apertures and the dust extraction fan or blower may be formed by suction hoses or by air channel conduits integrated with the chassis of the power trowel. A power trowel with one or more integrated air conduits extending from apertures arranged inside the protective cage structure 120 and to one or more locations outside of the protective cage structure 120 is disclosed herein. These integrated air conduits may contribute to an improved cyclonic effect inside the protective cage structure, and thus to an improved dust extraction performance by the dust extraction system. This power trowel may be fitted with a dust extractor or an air cleaner if the power trowel is used for dry polishing or dry grinding. In this case the air cleaner or dust extractor is simply attached to the existing air conduits. A dust extractor may either be mounted onto the power trowel or pulled alongside or behind the power trowel. On-board dust extractors are preferred when using larger power trowels, such as the power trowel 100, while separate dust extractors pulled along next to the power trowel may be more suitable for smaller machines, such as the power trowel 400.

[0070]The example 200 in FIG. 2 also shows an optional inner skirt 230 arranged offset from the outer skirt 240 in direction of the center of the protective cage 120. The volume 201 is in this case delimited by the inner and outer skirts 230, 240. This arrangement with inner and outer skirts offset from each other to create a narrow space in-between promotes the suction performance of the dust extraction system and improves the dust extraction capability of the dust extraction system. The slot between the inner and outer skirts functions like a vacuum cleaner which extracts dust from the concrete surface as the power trowel moves over the concrete surface during a dry polishing or dry grinding operation. One or more apertures 250 can be arranged in the space between the inner and the outer skirts. The offset distance between the skirts may be on the order of a few centimeters, such as between 5-10 centimeters.

[0071]It is appreciated that the inner skirt 230 does not have to extend all the way down to the concrete surface. According to some aspects a gap G is formed between the inner skirt 230 and the concrete surface to let at least some of the particle-laden air flow pass under the inner skirt before being extracted via the one or more inlet apertures of the dust extraction system 130.

[0072]FIGS. 10, 11, 12A-B illustrate an example of the optional inner skirt 230. FIG. 10 is a perspective view. FIG. 11 indicates the location of the two cross-section views B-B and C-C shown in FIGS. 12A-B.

[0073]The volume 201 is in this case also at least partly defined by inner and outer skirts 230, 240. An aperture 250 is arranged to draw the particle-laden airflow A out from the volume 201. In this example a further aperture 1000 is formed on an opposite end of the protective cage structure. Both apertures are formed by horizontally extending tubular members connected to a central vertical tube that extends upwards away from the surface that is processed by the trowel 100. The further aperture 1000 here acts as a ventilation aperture which regulates the air pressure in the interior of the protective cage structure, by allowing an amount of air to enter into the interior of the protective cage structure.

[0074]FIG. 11 indicates the location of cross-section views B-B and C-C, parts of which are shown in FIG. 12A and in FIG. 12B. Note that the inner skirt 230 extends further down in connection to the apertures 250, 1000 than it does elsewhere. This is because the dimension of the inner skirt 230 is adjusted to allow passage by the tool holders 110. The dimension of the inner skirt 230 along the two cross sections B-B and C-C can be seen in FIGS. 12A-B.

[0075]A gap G is preferably formed between the concrete surface and the inner skirt 230, such that particles from the center of the interior of the protective cage structure 120 can traverse under the inner skirt and into the volume between the inner skirt and the outer skirt.

[0076]FIGS. 14-17 illustrates an example where the inlet aperture of the dust extraction system is offset to one side of the protective cage structure, and where a ventilation aperture 1700 is formed between the outer skirt 240 and the protective cage structure. The skirt 240 in the example of FIG. 17 is preferably a floating skirt, i.e., a skirt which is only loosely attached to the protective cage structure such that it can move in the vertical direction. This improves the seal between the outer skirt 240 and the concrete surface.

[0077]FIG. 14 and FIG. 16 also show a blind aperture 1400, which can be opened up, e.g., in case it is desired to move the inlet aperture to the other side of the protective cage structure, or if a ventilation aperture is wanted.

[0078]A dust guide structure 310, 320 may be arranged in the volume 201 to guide the particle-laden airflow A to an aperture 250 of the dust extraction system 130, as exemplified in FIG. 3 and in FIG. 6. The dust guide structure 310, 320 is configured in dependence of the rotation direction R of the air inside the protection cage 220, to guide the flow of air towards the dust extraction system aperture 250.

[0079]The dust guide structure 310 is shaped as a funnel to guide the particle-laden air flow towards the inlet aperture of the dust extraction system 130, while the dust guide structure 320 is shaped as a wedge interleaved between the two counter-rotating tool holders 110 to guide the particle-laden air flow towards the inlet aperture of the dust extraction system 130.

[0080]FIG. 5 and FIG. 6 illustrate examples from a power trowel with a single set of rotatable tool holders, such as the power trowel 400 in FIG. 4. FIG. 5 shows an example with inner and outer skirts 230, 240 forming a narrow space or slot there in-between, while FIG. 6 illustrates an example with a single (outer) skirt 240 and an optional dust guide structure 310 arranged in the volume 201 to guide the particle-laden airflow A to an aperture 250 of the dust extraction system 130. The dust guide structure 310 is configured in dependence of a direction of rotation R of the rotatable tool holders.

[0081]FIG. 7A illustrates an example 700, where a set of rotatable tool holders 110 for processing the concrete surface comprises two brushes 710 configured to rotatably engage the concrete surface in use. Any number of brushes, i.e., at least one brush 710 may be used in this manner. A brush 710 arranged in this manner will disturb fine dust that has become adhered to the concrete surface, such that it more easily can be extracted via the dust extraction system apertures 250. Each brush 710 contacts the concrete surface and rotates together with the tool holders in a circular motion. The optional brush feature is advantageously combined with a pressurized air system that blows air onto the concrete surface in combination with the brush action to bring the dust into the air where it can be more easily extracted by the dust extraction systems disclosed herein. A scraper, such as a resilient material dough-scraper, spatula, or the like may be used instead of a brush with the same or at least similar technical effect. The scraper or spatula can be formed in, e.g., rubber, silicone, or soft plastic.

[0082]FIG. 7B schematically illustrates a set of rotatable tool holders 110. The tool holders 110 are attached to a central drive shaft 720 arranged to rotate in direction R as indicated in the Figure. The tool holders 110 extend radially out from the drive shaft. Trowel tools or grinding tools can be attached to the tool holders to process a concrete surface.

[0083]Some sets of rotatable tool holders 110 are attached to tiltable drive shafts 720 that are arranged to tilt T about one or two axes, as illustrated in FIG. 7B. A ride-on power trowel, such as the concrete surface processing equipment 100 in FIG. 1, normally comprises this type of tiltable tool holders. Tiltable tool holders allow an operator to maneuver the machine over a concrete surface.

[0084]It is an advantage to mount brushes or scrapers on two counter-rotating sets of tool holders, since the brushes or scrapers then work together in order to brush the dust particles towards a common point, where an aperture 250 of the dust extraction system can be arranged.

[0085]The power trowel 100, 400 optionally comprises a control unit 140 arranged to receive data from a dust sensor arrangement indicative of a dust concentration in an ambient environment of the power trowel 100, 400 and to generate a notification or alarm signal, e.g., via a display device arranged on the power trowel, in case the dust concentration does not satisfy a dust concentration acceptance criterion. Various dust sensors are known in the art and will therefore not be discussed in more detail herein. Dust sensors may be arranged both inside the protective cage structure 120 and outside the protective cage structure 120. A dust sensor may, e.g., be arranged in connection to the control seat of a ride-on power trowel 100 to measure the dust levels in vicinity of the operator of the machine. The control unit 140 may also use the data from the dust sensor to control an operation of the dust extraction system 130, i.e., the power of a fan or blower comprised in the dust extraction system 130, such that more power is used if high dust concentration levels are detected by the dust sensor compared to if lower dust concentration levels are measured. It is an advantage to integrate the dust sensor arrangement with the power trowel, since then the dust sensor system is always close to the source of the dust, but dust sensor arrangements external to the power trowel and connected to the control unit via wireless link may also be used. External air cleaners located remotely from the power trowel but in the same local area may also be controlled using the dust sensor arrangement integrated with the power trowel. These external air cleaners are then controlled with higher precision, and started sooner, since they are able to trigger based on dust levels close to the source. An air cleaner relying on a dust sensor located further away from the dust source will trigger later, since it will take some time for the dust to reach the remote dust sensor.

[0086]The power trowel 100, 400 may also comprise a control unit 140 arranged to receive data from a pressure sensor arrangement indicative of a pressure difference between an interior of the protective cage structure 120 and ambient environment of the power trowel 100, 400, and to generate a notification or alarm signal in case the pressure difference does not satisfy a pressure difference acceptance criterion. This way the control unit 140 has the capability to verify that the air stream A is actually generated which draws particle laden air out from the interior of the protective cage. The pressure difference measured between protective cage interior and exterior will rise in case the dust extraction system 130 suffers malfunction, such as a blocked filter or fan failure. Such events can be detected by the control unit 140 based on the sensed pressure difference, an alarm signal can be triggered by the control unit 140. The control unit 140 may also inactivate the power trowel in case the pressure difference does not satisfy a pressure difference acceptance criterion, to stop the generation of harmful dust in case the dust extraction system is not operated as intended.

[0087]The power trowel 100, 400 may furthermore comprise a control unit 140 arranged to receive data from a pressure sensor arrangement indicative of a pressure difference between an interior of the protective cage structure 120 and ambient environment of the power trowel 100, 400, and data from a water sensor or from water activation means indicative of the presence of water in the interior of the protective cage structure 120, and to generate a notification or alarm signal in case the pressure difference does not satisfy a pressure difference acceptance criterion while no water presence is indicated by the water sensor data. Wet power trowel operations, where water is added to the concrete surface during grinding or polishing does not require dust management in the same manner as dry polishing and dry grinding operations do. The control unit 140 can be used to selectively control power trowel functions and generate notifications based on the presence of water. In case the water supply stops, e.g. due to someone having closed a supply valve or due to hose leakage, or the like, then dust management may be required, in which case the control unit 140 may activate the dust management system, trigger a notification, or even inactivate the power trowel to prevent dry grinding operation without an effective dust management system. The presence of water can be automatically sensed by a water sensor, such as a conductive sensor arranged inside the protective cage structure 120, or inferred from the status of water activation means. Some power trowels arranged for wet operation comprise control means that an operator can use to activate and to deactivate a supply of water. The state of this “switch” can be used as indication of the presence of water.

[0088]One or more control units 140 may be arranged on the power trowel 100, 400. A control unit 140 may be configured to perform one or more of the above functions, i.e., to receive sensor data from one or more sensor systems and output control signals to one or more actuators and one or more display units, buzzers, and warning lights.

[0089]According to some aspects, the power trowel 100, 400 comprises a mounting bracket for holding a water tank or an air cleaner, such as the air cleaner 800 illustrated in FIG. 8. Thus, an operator can choose whether to have an on-board water-tank or an on-board air cleaner on the power trowel. It is an advantage that the water tank and the air cleaner are exchangeable and mountable at the same location since this reduces the effect on the center of gravity of the machine. A machine where the center of gravity changes may become more difficult for an operator to handle. The water tank is used for operations that do not generate harmful fine dust, where the air cleaner is not needed. For high gloss dry polishing operations, the water tank can be exchanged for the air cleaner to reduce the amount of harmful dust in the ambient environment. The mounting bracket may be located in vicinity of attachment interfaces for attaching an air cleaner to air conduits leading to the apertures 250, and also to attachment interfaces for attaching a water tank to water conduits leading to water nozzles used to dispense water during wet grinding operations.

[0090]According to some aspects, the power trowel comprises an on-board air cleaner, such as the example air cleaner 800 in FIG. 8, with an air outlet directed at an expected location of an operator of the power trowel. This way the operator of the machine, such as a person walking behind the machine to guide it or a person sitting in a chair of a ride-on trowel will have more clean air in his or her immediate surrounding, which is an advantage. For a walk-beside power trowel the expected location of the operator can be determined based on the location of the handle portion used by the operator to guide the machine. For a ride-on power trowel the expected location is the operators seat on top of the power trowel.

[0091]According to some aspects, the power trowel comprises a pressurized air system arranged to provide a pressurized flow of air in the interior of the protective cage structure, and preferably in the sealed volume, i.e., inside the outer skirt or in between the outer and inner skirt in case there are two offset skirts. The pressurized flow of air may, e.g., be directed at the concrete surface in order to disturb dust adhered to the concrete surface. A control unit of the power trowel may be arranged to control the pressurized air system to deliver bursts of air to loosen dust from the concrete surface, thus facilitating capturing dust particles in the particle-laden airflow A. This also leaves a cleaner surface after processing, since dust is loosened from the concrete surface traversed by the machine and extracted by the dust extraction system.

[0092]According to some aspects the power trowel 100, 400 and/or the dust extraction system 130 is at least partly powered by a combustion engine that generates exhaust in use. The exhaust from the combustion engine can then be guided via a conduit such as a tube or hose from the combustion engine to the at least one further aperture 250. This means that the exhaust is injected into the volume under the protective cage structure, and then extracted by the dust extraction system which filters the extracted air, thereby removing at least some of the unwanted particles and gas in the exhaust. This way an exhaust cleaning system can be provided in an efficient manner.

[0093]FIG. 9 schematically illustrates, in terms of a number of functional units, the general components of a control unit 140. Processing circuitry 910 is provided using any combination of one or more of a suitable central processing unit CPU, multiprocessor, microcontroller, digital signal processor DSP, etc., capable of executing software instructions stored in a computer program product, e.g. in the form of a storage medium 930. The processing circuitry 910 may further be provided as at least one application specific integrated circuit ASIC, or field programmable gate array FPGA.

[0094]Particularly, the processing circuitry 910 is configured to cause the control unit 140 to perform a set of operations, or steps, such as the operations discussed above. For example, the storage medium 930 may store the set of operations, and the processing circuitry 910 may be configured to retrieve the set of operations from the storage medium 930 to cause the device to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus, the processing circuitry 910 is thereby arranged to execute methods as herein disclosed.

[0095]The storage medium 930 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

[0096]The control unit 140 may further comprise an interface 920 for communications with at least one external device. As such the interface 920 may comprise one or more transmitters and receivers, comprising analogue and digital components and a suitable number of ports for wireline or wireless communication.

[0097]The processing circuitry 910 controls the general operation of the control unit 140, e.g., by sending data and control signals to the interface 920 and the storage medium 930, by receiving data and reports from the interface 920, and by retrieving data and instructions from the storage medium 930.

[0098]Many of the features discussed herein are applicable separately with respective technical effects and advantages that are not inextricably linked to any of the other features disclosed herein.

[0099]The present disclosure for instance relates to surface processing equipment 100, 400 comprising two sets of counter-rotating tool holders 110 for processing a concrete surface that comprises innovative features not inextricably linked to the other features discussed herein. The equipment 100, 400 comprises a protective cage structure 120 arranged to enclose the sets of tool holders 110, and a dust extraction system 130 arranged to draw a particle-laden airflow A from an interior of the protective cage structure 120 via at least one inlet aperture 250, and to capture dust particles in the particle-laden airflow A. A dust guide structure 310 that is configured in dependence of a rotation direction R of the air inside the protective cage structure 120 is arranged in the volume 201 between the counter-rotating tool holders 110 to guide the particle-laden airflow A to an inlet aperture 250 of the dust extraction system 130. This dust guide structure improves the efficiency of the dust extraction system by guiding the particle-laden air flow towards the inlet aperture or apertures of the dust extraction system.

[0100]There is also disclosed surface processing equipment 100, 400 comprising one or more sets of rotatable tool holders 110 for processing a concrete surface which comprises innovative features not inextricably linked to the other features discussed herein. This particular equipment 100, 400 comprises a protective cage structure 120 arranged to enclose the sets of tool holders 110, a dust extraction system 130 arranged to draw a particle-laden airflow A from an interior of the protective cage structure 120 via at least one aperture 250, and to capture dust particles in the particle-laden airflow A, an outer skirt 240 arranged around the one or more sets of rotatable tool holders 110 and to seal a volume 201 against the concrete surface, where at least one aperture 250 of the dust extraction system 130 is arranged in the volume 201, and an inner skirt 230 arranged offset from the outer skirt 240 to form a slot there in between, where a gap G is formed between the inner skirt 230 and the concrete surface. This gap G improves the efficiency of the dust extraction system and improves the extraction of dust from the interior of the protective cage structure 120.

[0101]There is also disclosed surface processing equipment 100, 400 comprising one or more sets of rotatable tool holders 110 for processing a concrete surface. The equipment 100, 400 comprises a protective cage structure 120 arranged to enclose the sets of tool holders 110, and a dust extraction system 130 arranged to draw a particle-laden airflow A from an interior of the protective cage structure 120 via at least one aperture 250, and to capture dust particles in the particle-laden airflow A. At least one set of rotatable tool holders 110 for processing the concrete surface comprises one or more vanes 1300 configured to generate a rotation of the air in the interior of the protective cage structure 120. These vanes improve the efficiency of the dust extraction system by forcing the dust radially outwards in the interior of the protective cage structure 120.

[0102]There is also disclosed surface processing equipment 100, 400 comprising one or more sets of rotatable tool holders 110 for processing a concrete surface that comprises innovative features that are also not inextricably linked to the other features discussed herein. This equipment 100, 400 comprises a protective cage structure 120 arranged to enclose the sets of tool holders 110, a dust extraction system 130 arranged to draw a particle-laden airflow A from an interior of the protective cage structure 120 via at least one aperture 250, and to capture dust particles in the particle-laden airflow A, and a control unit 140 arranged to receive data from a dust sensor arrangement indicative of a dust concentration in an ambient environment of the equipment 100, 400 and to generate a notification or alarm signal in case the dust concentration does not satisfy a dust concentration acceptance criterion. This way an operator is made aware of potentially dangerous levels of dust in the ambient environment.

[0103]There is also disclosed surface processing equipment 100, 400 comprising one or more sets of rotatable tool holders 110 for processing a concrete surface which comprises a protective cage structure 120 arranged to enclose the sets of tool holders 110, a dust extraction system 130 arranged to draw a particle-laden airflow A from an interior of the protective cage structure 120 via at least one aperture 250, and to capture dust particles in the particle-laden airflow A, and a control unit 140 arranged to receive data from a pressure sensor arrangement indicative of a pressure difference between an interior of the protective cage structure 120 and ambient environment of the equipment 100, 400, and to generate a notification or alarm signal in case the pressure difference does not satisfy a pressure difference acceptance criterion. This way an operator is made aware of the potential problem in the dust extraction system and can take action to restore the desired pressure difference.

[0104]There is furthermore disclosed surface processing equipment 100, 400 comprising one or more sets of rotatable tool holders 110 for processing a concrete surface. The equipment 100, 400 comprises a protective cage structure 120 arranged to enclose the sets of tool holders 110, a dust extraction system 130 arranged to draw a particle-laden airflow A from an interior of the protective cage structure 120 via at least one aperture 250, and to capture dust particles in the particle-laden airflow A, and a control unit 140 arranged to receive data from a pressure sensor arrangement indicative of a pressure difference between an interior of the protective cage structure 120 and ambient environment of the equipment 100, 400, and data from a water sensor and/or or from water activation means indicative of the presence of water in the interior of the protective cage structure 120, and to generate a notification or alarm signal in case the pressure difference does not satisfy a pressure difference acceptance criterion while no water presence is indicated by the water sensor data. This way it becomes easier to use the machine with and without added water.

[0105]There is also disclosed surface processing equipment 100, 400 comprising one or more sets of rotatable tool holders 110 for processing a concrete surface. The equipment 100, 400 comprises a protective cage structure 120 arranged to enclose the sets of tool holders 110, a dust extraction system 130 arranged to draw a particle-laden airflow A from an interior of the protective cage structure 120 via at least one aperture 250, and to capture dust particles in the particle-laden airflow A, and a control unit 140 arranged to detect presence of a grinding tool and/or a trowel tool attached to a tool holder 110, and to activate and/or adjust an operating power of the dust extraction system 130 based on the presence or absence of a grinding tool attached to the tool holder 110. This improves the power efficiency of the dust extraction system without jeopardizing the dust extraction performance.

[0106]There is also disclosed surface processing equipment 100, 400 comprising one or more sets of rotatable tool holders 110 for processing a concrete surface. The equipment 100, 400 comprises a protective cage structure 120 arranged to enclose the sets of tool holders 110, a dust extraction system 130 arranged to draw a particle-laden airflow A from an interior of the protective cage structure 120 via at least one aperture 250, and to capture dust particles in the particle-laden airflow A, and a control unit 140 arranged to receive data from a water sensor and/or or from water activation means indicative of the presence of water in the interior of the protective cage structure 120, and to activate the dust extraction system 130 based on the presence or absence water inside the protective cage. This makes it more convenient to operate the equipment, since the dust extraction system will be automatically activated when dry operations are performed.

[0107]There is also disclosed surface processing equipment 100, 400 comprising one or more sets of rotatable tool holders 110 for processing a concrete surface. The equipment 100, 400 comprises a protective cage structure 120 arranged to enclose the sets of tool holders 110, a dust extraction system 130 arranged to draw a particle-laden airflow A from an interior of the protective cage structure 120 via at least one aperture 250, and to capture dust particles in the particle-laden airflow A, where the dust extraction system 130 is arranged in a position vertically overlapping the protective cage structure 120. This makes the equipment more spatially efficient since its footprint is reduced. There is also disclosed surface processing equipment 100, 400 comprising one or more sets of rotatable tool holders 110 for processing a concrete surface. The equipment 100, 400 comprises a protective cage structure 120 arranged to enclose the sets of tool holders 110, a dust extraction system 130 arranged to draw a particle-laden airflow A from an interior of the protective cage structure 120 via at least one aperture 250, and to capture dust particles in the particle-laden airflow A, where at least one further aperture 250 is arranged in the protective cage structure 120 to allow an amount of air to enter into the interior of the protective cage structure 120, where the equipment (100, 400) and/or the dust extraction system (130) is at least partly powered by a combustion engine that generates exhaust in use, where the exhaust from the combustion engine is guided via a conduit from the combustion engine to the at least one further aperture (250). This way exhaust treatment is provided by the dust extraction system, which is an advantage.