Dust extraction device for a hand-held power tool

Abstract

Dust extraction device (10) for a hand-held power tool (100), in particular for a rotary hammer (100), with a housing (12), wherein a dust collection chamber (30) with a filter unit (38) and an electric motor (34) for generating an airflow are provided in the housing (12) such that the dust generated during a work operation is conveyed by means of the airflow through an air duct via the filter unit (38) into the dust collection chamber (30), and wherein a filter cleaning unit (40) is provided in the housing (12) for cleaning the filter unit (38), characterized in that the filter cleaning unit (40) has an impact mechanism (42) with a hammer (44) and a trigger (46) integrally connected thereto, wherein the filter cleaning unit (40) is rotatably mounted about an axis of movement (48).that when the trigger (46) is actuated, the hammer (44) is moved away from the filter unit (38) against the force of a spring (50) and, when the trigger (46) is suddenly released, snaps against a housing section (52) of the housing (12) which is directly adjacent to the filter unit (38) as a result of the force of the spring (50).

Description

[0001] The invention relates to a dust extraction device for a hand-held power tool, in particular for a rotary hammer according to the preamble of independent claim 1. State of the art

[0002] Dust extraction devices for handheld power tools are already known in the art. They serve to capture the dust generated during work processes such as drilling, chiseling, grinding, sawing, etc., directly at the point of origin, thus reducing the exposure for the operator and the surrounding environment. Such a dust extraction device, known from German patent application DE 10 2018 215 308 A1, typically has a housing containing a dust collection chamber with a filter unit and an electric motor for generating an airflow. The dust generated during a work process is conveyed by the airflow through an air duct, over the filter unit, and into the dust collection chamber. To maintain the suction effect over time, it is necessary to clean the filter unit, on whose surface the dust accumulates, regularly. For this purpose, a filter cleaning unit is provided in the housing.

[0003] However, the filter cleaning of known devices is often insufficiently effective and / or has an overly complex and failure-prone design. Inadequate cleaning of the filter unit leads to a rapid decrease in suction power, necessitating more frequent work interruptions for manual cleaning or filter replacement.

[0004] The present invention is therefore based on the objective of providing a dust extraction device of the type mentioned at the outset, the filter unit of which can be cleaned particularly effectively and reliably using simple, robust and cost-effective means. Advantages of the invention

[0005] This problem is solved by a dust extraction device with the features of claim 1. The solution according to the invention is characterized in that the filter cleaning unit has an impact mechanism with a hammer and a trigger integrally connected thereto. Crucially, the filter cleaning unit is rotatably mounted about an axis of movement such that, when the trigger is actuated, the hammer is moved away from the filter unit against the force of a spring. Upon sudden release of the trigger, the hammer, due to the force of the spring, snaps against a housing section that directly adjoins the filter unit.

[0006] This design generates a high level of impulse energy, which is then precisely directed into the housing in the immediate vicinity of the filter unit. The sudden, hard impact of the hammer against the housing section results in a brief, high-frequency vibration that is directly transmitted to the adjacent filter unit. This effective impact ensures sufficient cleaning of the adhering dust from the filter surface. Unlike systems that directly strike or shake the filter, the solution according to the invention avoids direct mechanical stress on the sensitive filter unit itself. Instead, the cleaning energy is introduced indirectly, which increases the service life of the filter unit.The one-piece connection of hammer and trigger, along with the simple rotary bearing around a single axis of movement and a spring, results in a mechanically very robust, easy-to-use, and cost-effective impact mechanism that ensures consistently high cleaning performance.

[0007] In the context of the invention, the term "one-piece" means that the hammer and the trigger are manufactured as a single, indivisible physical unit. This can be achieved, for example, through a casting, forging, or injection molding process. There are no separate connections such as screws, rivets, welds, or adhesive joints. This integral design ensures a direct and lossless transmission of force from the actuation of the trigger to the positioning of the hammer and gives the entire striking mechanism high mechanical stability, reduces the number of components, and minimizes potential sources of error.

[0008] The statement that the housing section is directly adjacent to the filter unit describes a close spatial and functional relationship such that no significant vibration-damping or energy-absorbing components lie between this specific section of the housing and the filter unit. The housing section may be in direct contact with the filter unit, for example, by forming part of its mounting or frame, or it may be separated from it only by a minimal gap. The aim is to ensure that the shock wave generated by the hammer blow is transmitted to the filter unit with maximum intensity and minimal loss in order to effectively shake off the adhering dust particles.

[0009] The force of the spring refers to the mechanical restoring force exerted by the spring when it is deformed from its rest position. In this case, the spring is tensioned by actuating the trigger, thereby storing potential energy. When the trigger is suddenly released, this stored energy is abruptly released and converted into kinetic energy. This energy accelerates the hammer towards the housing section. The dimensions and characteristics of the spring are crucial for the strength of the generated impulse and thus for the effectiveness of the cleaning process.

[0010] In another embodiment, the dust extraction device features a telescopic unit that is linearly movable along a working axis relative to the housing. This unit includes a telescopic tube with a suction head attached to its front end for extracting the dust generated during the work process. This design allows for flexible adjustment of the extraction length to accommodate different drill bit lengths and drilling depths. The operator can precisely adjust the position of the suction head to the work area, ensuring consistently high dust capture efficiency directly at the source. This not only improves the cleanliness of the work environment but also increases user comfort and the versatility of the entire device.

[0011] It is particularly advantageous if the axis of movement is positioned between the hammer and the trigger. This arrangement creates a leverage effect. A small, comfortable movement of the trigger results in a larger deflection of the hammer. This allows the spring to be effectively tensioned with minimal effort from the operator, thus generating high impact energy and significantly improving ergonomics and operating efficiency.

[0012] In another embodiment, the axis of movement is essentially perpendicular to the working axis. This orthogonal alignment of the axes results in a particularly compact and ergonomically advantageous design. The trigger is actuated transversely to the feed direction of the hand-held power tool, enabling intuitive operation without interrupting the work process and preventing collisions between the operating elements and the workpiece or the work environment.

[0013] The spring is designed as a tension or compression spring, supported on one side by the housing and on the other by the striking mechanism. This design offers high flexibility in construction and the choice of spring characteristics. Standardized tension or compression springs are cost-effective and available in a wide range of strengths. Their separate arrangement simplifies assembly and maintenance and allows for easy adjustment of the spring force to the desired impact intensity.

[0014] It is also possible for the impact mechanism to include a rotating cam disc that acts on the trigger. This design allows for automation of the filter cleaning process. Instead of purely manual operation, the impact mechanism can, for example, be additionally driven by the motor of the hand-held power tool or a separate small electric motor. This ensures regular and automatic cleaning of the filter unit without user intervention, resulting in consistently high suction power throughout operation.

[0015] If this automated solution is chosen, it is advantageous for the spring to be designed as a torsion spring, mounted on a pin of the housing that runs parallel to the axis of movement. Using a torsion spring in this arrangement represents an extremely compact, space-saving, and integrated solution. The spring and the drive element form a functional unit, which simplifies assembly, reduces the number of individual parts, and ensures very direct and efficient storage and release of impact energy.

[0016] For particularly effective energy transfer, a transmission element, especially in the form of an anvil, can be positioned between the hammer and the dust collection chamber. The hammer strikes this anvil, creating a defined striking surface with high mass and rigidity. The impact of the hammer on this anvil generates a maximum shock wave with minimal energy loss. This concentrated impulse transfer to the immediately adjacent filter unit results in even more effective and highly efficient cleaning, even of stubbornly adhering dust particles.

[0017] Finally, the impact force of the impact mechanism, particularly via the spring, can be adjusted. This adjustability allows the operator to adapt the cleaning intensity to the specific amount and type of dust. For fine, tightly adhering dust, a high impact force can be selected, while for less critical applications, a lower force suffices, reducing mechanical stress on the components and noise generation. This increases versatility and optimizes the device's service life. Examples of implementation Drawing

[0018] The invention is described below with reference to the Fig. Figures 1 to 5 are explained by way of example, whereby identical reference symbols in the figures indicate identical components with the same function.

[0019] They show: Fig. 1. A perspective view of a dust extraction device with an extended telescopic unit, Fig. 2: A first embodiment of the dust extraction device according to the invention in the area of ​​the dust collection chamber in a sectional view, which shows a manual impact mechanism with a compression spring, Fig. 3: A second embodiment of an alternative design of the striking mechanism with a torsion spring and a cam disc for automated actuation in a detailed view, Fig. 4: the dust extraction device according to Fig. 3 in the assembled state on a hand-held power tool designed as a rotary hammer to illustrate the drive mechanism for automatic filter cleaning via a drive rail on the telescopic tube and Fig. 5: an exploded view of the operating mechanism for driving the automated impact mechanism including detent and coupling elements for adjusting the impact force. Description of the exemplary implementations

[0020] Fig. Figure 1 shows a perspective view of a dust extraction device 10 with a housing 12 for a hand-held power tool 100, in particular a rotary hammer (see also Figure 1). Fig. 4) The dust extraction device 10 can be connected to the hand-held power tool 100 without tools via a housing interface 14, which includes a guide rail extending to a tool axis 16 and an electronic interface (both not shown in detail) on each side of the housing 12. For this purpose, a correspondingly complementary part of the housing 14 of the dust extraction device 10 surrounds a housing 102 of the hand-held power tool 100. The dust extraction device 10 is supplied with energy from an interchangeable battery pack 106 via the electronic interface, depending on an operating switch 104 of the hand-held power tool 100. However, it is also conceivable that the dust extraction device 10 can be connected directly to an interchangeable battery pack 106 for power supply without tools via a corresponding electromechanical interface.Since this is of minor importance for the present invention, it will not be discussed in further detail. The dust extraction device 12 also includes a locking unit (not shown) for locking to the hand-held power tool 100, which can be unlocked again via at least one push button 18 provided on the side of the housing 12.

[0021] A suction head 22 is arranged at the front end of a telescopic unit 20 of the dust extraction device 10. The telescopic unit 20 comprises a telescopic tube 24, which is linearly movable along the working axis 16 within the housing 12 of the extraction device 10. The suction head 22 has a hollow cylindrical suction eye 26 that coaxially engages a tool, in particular a drill bit, along the working axis 16 during the course of work. The telescopic unit 20 is in Fig. Figure 1 shows the telescopic unit 20 in an extended position, in which it has a maximum distance to the housing 12 of the extraction device 10 due to a spring preload (not shown in detail). The maximum extension and retraction length of the telescopic unit 20 can be adjusted via correspondingly releasable stops 28. The extraction device 10 has a dust collection chamber 30, which can be connected to the housing 14 by means of a snap-fit ​​connection (not shown in detail) and can be detached from it again without tools using a push button 32.

[0022] Fig. Figure 2 shows a sectional view of the dust extraction device 10 in the area of ​​the dust collection chamber 30. During operation, an airflow is generated by a blower unit 36 ​​comprising an electric motor 34. This airflow serves to extract dust from a work area of ​​the tool. The airflow is drawn in through the suction opening 26 and guided via an air duct through the telescopic tube 24 into the dust collection chamber 30. A filter unit 38 is arranged in the dust collection chamber 30 and is designed to filter the dust from the airflow. The filter unit 38 is preferably designed as a HEPA filter (High-Efficiency Particulate Air / Airborne Particulate Matter). However, other types of particle and suspended particle filters are also conceivable. A filter cleaning unit 40 with an impact mechanism 42 is arranged in the housing 14 of the dust extraction device 10.

[0023] The impact mechanism 40 consists of a hammer 44 and a trigger 46 integrally connected to it. The filter cleaning unit 40 is such that it is positioned essentially perpendicular to the working axis 16 (cf. Fig. 1) and the axis of movement 48, located approximately midway between the hammer 44 and the trigger 46, is rotatably mounted such that when the trigger 46 is actuated, the hammer 44 is moved away from the filter unit 38 against the force of a spring 50. To achieve this, an operator pushes the trigger 46 with a finger from its rest position towards the dust collection chamber 30 to pre-tension the spring 50 and move the filter cleaning unit 42 into a pre-tensioned position (shown with dashed lines). Upon sudden release of the trigger 46, the hammer 44, due to the force of the spring 50, strikes a housing section 52 of the housing 14, which is directly adjacent to the filter unit 38. The housing section 52, located between the hammer 44 and the dust collection chamber 38, thus serves as a transmission element in the form of an anvil 54 against which the hammer 44 strikes.The spring 50 is designed as a compression spring 56, which is supported on one side by the housing 14 and on the other side by a projection 58 opposite the hammer 44 on the striking mechanism 42. However, it is also conceivable that the spring 50 is designed as a tension spring, which would then be supported on the striking mechanism 42 in the area of ​​the trigger 46. In this way, a high impulse energy is generated and introduced very precisely into the housing 14 in the immediate vicinity of the filter unit 38. The sudden, hard impact of the hammer 44 against the housing section 52 or the anvil 54 results in a brief, high-frequency vibration, which is transmitted directly to the adjacent filter unit 38, thereby ensuring sufficient cleaning of the adhering dust from the filter surface.The one-piece connection of hammer 44 and trigger 46, as well as the simple rotary bearing around the axis of movement 48, in combination with the spring 50, results in a mechanically very robust, easy-to-use and cost-effective impact mechanism that ensures a consistently high cleaning performance.

[0024] Fig. Figure 3 shows an alternative embodiment of the impact mechanism 42 of the filter unit 40 in a detailed view. Accordingly Fig. 2. The striking mechanism 42 comprises the hammer 44 and the trigger 46, which is integrally connected to the hammer 44. These are now arranged at a substantially right angle to each other via the axis of movement 48. For pre-tensioning the striking mechanism 42, the spring 50 is designed as a torsion spring 60, which is supported on one side by the striking mechanism 42 and on the other side by a pin 61 of the housing 12. Furthermore, the filter cleaning unit 40 comprises a cam disk 64 rotating counterclockwise about a rotation axis 62 arranged parallel to the axis of movement 48. This cam disk, by means of three axial cam projections 66, preferably automates the actuation of the hammer 44 via the trigger 46.The arrangement of the axis of movement 48 between the hammer 44 and the trigger 46 creates a leverage effect that enables effective force transmission such that the rotation of the cam disk 64, via each cam projection 66 and the trigger 46, generates a preload on the torsion spring 60. This preload, after the cam projection 66 engages the trigger 46, generates high impulse energy and directs it precisely into the housing section 52 of the housing 14, designed as an anvil 54, in close proximity to the filter unit 38 (not shown). Due to the multiple axial cam projections 66, the rotation of the cam disk 64 triggers the striking mechanism 42 multiple times with a single revolution. Depending on the dimensions of the trigger 46 and the cam disk 64, a different number of cam projections 66 is conceivable.Instead of axial cam projections 66, the cam disk can also be designed with radial cam projections 66. A cam disk or an eccentric are also conceivable. The cam disk 64 can be driven, for example, by an electric motor (not shown), purely mechanically by hand, or semi-automatically via the telescopic unit 20. The latter will be described in more detail below. Fig. 4 and Fig. 5 will be described.

[0025] Fig. Figure 4 shows a further embodiment of the dust extraction device 10 in the mounted state on a hand-held power tool 100 designed as a rotary hammer. As already mentioned in the Fig. 1 and Fig. As noted in section 2, the electric motor 34 of the dust extraction device 10 is supplied with energy via the interchangeable battery pack 106 inserted into the rotary hammer, depending on the activation of the operating switch 104. In contrast to Fig. 1 The telescopic tube 24 of the telescopic unit 20 has a drive rail 68 for a drive pinion 70 of the filter cleaning unit 40, the drive rail 68 extending over the axial length of the telescopic tube 24 and moving linearly into the housing 12 of the dust extraction device 10 along the working axis 16 together with the telescopic tube 24 during the work progress. Through this operative connection between the drive rail 68 and the drive pinion 70, the Fig. 3 cam discs shown 64 (in Fig. (4 not shown) is set into a counterclockwise rotational movement to trigger the impact mechanism 42 of the filter cleaning unit 40 in the manner described for cleaning the filter unit 38. It should be noted that the drive rail 68 can be, for example, a rack or pinion, and the drive pinion 70 can be designed accordingly as a pinion engaging in the holes or teeth of the rack or pinion.

[0026] In Fig. Figure 5 is an exploded view of an operating mechanism 72 for driving the striking mechanism 42 according to the Fig. 3 and Fig. Figure 4 shows the drive pinion 70 and the cam disc 64. The operating mechanism 72 comprises, in addition to the drive pinion 70 and the cam disc 64, a detent disc 74, which interacts with a detent element 76 spring-mounted on the housing 14 of the dust extraction device 10, a coupling unit 82 consisting of a first and a second coupling disc 78, 80, and a torsion spring 84, which together are arranged on two drive shafts 86, 88 that are separable from one another along the axis of rotation 62 via the coupling unit 82. To pre-tension the torsion spring 84, the two drive shafts 86, 88 are initially connected to each other in a rotationally fixed manner via the coupling unit 82. For this purpose, the first and the second coupling disc 78, 80 are connected to each other by means of a device of the coupling unit 82 (not shown in detail) such that they engage with each other via corresponding projections and recesses.If the telescopic tube 24 of the dust extraction device 10 is inserted during the work process, this causes a rotational movement of the drive pinion 70 via the drive rail 68, thereby also pre-tensioning the torsion spring 84. The cam disc 64 advantageously has a freewheel, so that it cannot rotate clockwise when the torsion spring 84 is pre-tensioned. To prevent the torsion spring 84 from relaxing again when the telescopic tube 24 extends automatically, the detent disc 74, in conjunction with the detent element 76, prevents the two drive shafts 86, 88 from rotating counterclockwise. By repeatedly inserting the telescopic tube 24, the pre-tension of the torsion spring 84 can be increased to set a desired impact force of the impact mechanism 42. Furthermore, the clutch unit 82 is designed as a latching clutch, which prevents over-tensioning of the torsion spring 84.If the torsion spring 84 is sufficiently pre-tensioned and the filter unit 38 is to be cleaned by means of the impact mechanism 42, the first and second clutch discs 78, 80 of the clutch unit 82 can be disengaged via the aforementioned device, so that the torsion spring 84 relaxes counterclockwise and drives the cam disc 64 via the second drive shaft 88. It should be noted that the exploded view is only illustrative and, in particular, the two drive shafts 86, 88 can be so short that the entire working mechanism 72 is very compact along the axis of rotation 62.

[0027] Finally, it should be noted that the illustrated embodiments do not refer to the Fig. 2 to 5 are still limited to the exact design of the individual components. Likewise, a combination of parts of the components described in the Fig. 3 and Fig. 5 semi-automatic drive and operating mechanism 72 shown with the in Fig. 2 shown manual operation possible, for example to realize an adjustable mechanical energy storage device in the form of the torsion spring 84. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2018 215 308 A1

[0002]

Claims

[1] Dust extraction device (10) for a hand-held power tool (100), in particular for a rotary hammer (100), comprising a housing (12), wherein the housing (12) contains a dust collection chamber (30) with a filter unit (38) and an electric motor (34) for generating an airflow such that the dust generated during a work operation is conveyed by means of the airflow through an air duct over the filter unit (38) into the dust collection chamber (30) and wherein the housing (12) contains a filter cleaning unit (40) for cleaning the filter unit (38), characterized by, that the filter cleaning unit (40) has a striking mechanism (42) with a hammer (44) and a trigger (46) integrally connected thereto, wherein the filter cleaning unit (40) is rotatably mounted about an axis of movement (48) such that when the trigger (46) is actuated, the hammer (44) is moved away from the filter unit (38) against the force of a spring (50) and, when the trigger (46) is suddenly released, strikes a housing section (52) of the housing (12) which is directly adjacent to the filter unit (38) as a result of the force of the spring (50). [2] Dust extraction device (10) according to claim 1, characterized by , that the dust extraction device (10) has a telescopic unit (20) which is linearly movable along a working axis (16) relative to the housing (12) and which has a telescopic tube (24) with a suction head (22) attached to its front end for extracting the dust generated during the work process. [3] Dust extraction device (10) according to one of the preceding claims, characterized by , that the axis of movement (48) is arranged between the hammer (44) and the trigger (46). [4] Dust extraction device (10) according to one of the preceding claims, characterized by that the axis of movement (48) is essentially perpendicular to the working axis (16). [5] Dust extraction device (10) according to one of the preceding claims, characterized by , that the spring (50) is designed as a tension or compression spring (56) which is supported on one side by the housing (12) and on the other side by the striking mechanism (42). [6] Dust extraction device (10) according to one of the preceding claims, characterized by , that the striking mechanism (42) comprises a rotating cam disk (64) which acts on the trigger (46). [7] Dust extraction device (10) according to claim 6, characterized by, that the spring (50) is designed as a torsion spring (60) which is arranged on a pin (62) of the housing (12) which runs parallel to the axis of movement (48). [8] Dust extraction device (10) according to one of the preceding claims, characterized by , that a transmission element (52) of the housing section (52), in particular in the form of an anvil (54), is arranged between the hammer (44) and the dust collection chamber (30), against which the hammer (44) strikes. [9] Dust extraction device (10) according to one of the preceding claims, characterized by , that the impact force of the impact mechanism (42), in particular via the spring (50), is adjustable.

Images