Impact screwdriver

Abstract

The invention relates to an impact screwdriver (10) comprising a rotary impact drive (22), wherein the rotary impact drive (22) has a drive shaft (28) extending along a longitudinal axis (L), wherein the rotary impact drive (22) has a striker (30), which is arranged so as to be displaceable along the longitudinal axis (L), and an anvil (32) which can be contacted by the striker (30) along a circumferential direction (U) relative to the longitudinal axis (L). According to the invention, the rotary impact drive (22) has at least one impact damper (40, 42, 44) which is designed to damp an impact of the striker (30), in particular onto the anvil (32), in a longitudinal impact direction (LR) parallel to the longitudinal axis (L). It is thus possible to reduce or avoid undesired vibrations such that health risks when using the impact screwdriver (10) can be reduced.

Description

[0001] impact wrench

[0002] Description

[0003] The invention relates to an impact wrench comprising a rotary impact drive.

[0004] Using rotary impacts, a rotary impact drive of an impact wrench can develop high torques, for example to tighten or loosen a screw.

[0005] However, relatively strong vibrations can often occur during use of an impact wrench. Health risks from associated noise or vibrations transmitted to the user's body therefore often preclude prolonged use of an impact wrench.

[0006] The object of the present invention is therefore to offer an impact wrench whose use is expected to pose fewer health risks.

[0007] The object is achieved by an impact wrench comprising a rotary impact drive, wherein the rotary impact drive has a drive shaft extending along a longitudinal axis, wherein the rotary impact drive has a striker arranged displaceably along the longitudinal axis and an anvil contactable by the striker along a circumferential direction to the longitudinal axis, and wherein the rotary impact drive has at least one shock absorber which is configured to dampen an impact of the striker in a longitudinal impact direction parallel to the longitudinal axis.

[0008] The impact of the striker can be applied, in particular, to the anvil. Alternatively or additionally, the impact of the striker can also be applied to the drive shaft or to a part of the rotary impact drive connected to the drive shaft and / or the anvil.

[0009] During operation of the impact wrench, the impactor can strike the anvil, particularly along its longitudinal axis and its circumferential direction. The impact, particularly repeated impacts, of the impactor on the anvil along its longitudinal direction can cause unwanted vibrations. The at least one shock absorber can reduce the amount of these unwanted vibrations or prevent them entirely.

[0010] Health impairments of an impact wrench user can be minimized or completely avoided due to the reduced or completely prevented vibrations.

[0011] In particular, unwanted vibrations can be reduced or completely avoided at the source and / or at the time of their potential occurrence. Additional vibration-damping measures can be dispensed with. For example, it may be obsolete to mount the rotary impact drive within the impact wrench housing with vibration-damped mounting on the housing. Alternatively, it is conceivable to provide such vibration decoupling of the rotary impact drive from the housing in order to further reduce vibrations that can be transmitted to the housing, in particular to a handle of the housing, and / or to the user.

[0012] The shock absorber can be located between the striker and the anvil. It can be located on an impact surface on the anvil facing the longitudinal direction of impact.

[0013] Designing a shock absorber in such a range can be very cost-effective. It has also been shown that a significant portion of unwanted vibrations can be avoided.

[0014] Alternatively or additionally, the shock absorber can be located between the striker and the drive shaft. If the shock absorber is located between the striker and the drive shaft, the drive shaft can be directly and / or indirectly coupled to the anvil. Thus, a relative movement of the striker relative to the anvil in the longitudinal direction of impact can also be dampened and / or damped.

[0015] A further reduction of vibrations can be achieved if a recoil damper is formed between a back side of the striker facing opposite to the longitudinal direction of impact and a recoil surface opposite the anvil facing opposite to the longitudinal direction of impact and limiting movement of the striker along the longitudinal axis.

[0016] The shock absorber may comprise a material from which the anvil is not formed and / or which the anvil does not comprise.

[0017] The at least one shock absorber can, for example, comprise a plastic and / or a latex-containing material, such as a rubber-containing material, in particular rubber. Such materials are inexpensive and can provide sufficient damping.

[0018] The shock absorber can be designed to dampen the shock inelastically or at least partially inelastically. For example, it can be designed to absorb at least 50 percent of the kinetic energy attributable to the movement of the racket along its longitudinal axis.

[0019] The damping effect can also be adjusted and / or tuned to a particular rotary impact drive and / or impact wrench by varying material parameters. For tuning, parameters such as the peak power of the impact wrench, the typical power of the impact wrench, the rotational frequency, the peak pulse, and / or the like can be taken into account.

[0020] The shock absorber can also comprise a fluid, in particular an oil- and / or water-containing liquid, or a gas, in particular air. This allows, for example, a pneumatic and / or hydraulic shock absorber to be implemented. The damping effect of the shock absorber can be adjustable. For example, the fluid can comprise a substance with adjustable viscosity. The viscosity can be adjusted, for example, electrically and / or magnetically.

[0021] The shock absorber can be designed to have speed- and / or acceleration-dependent damping. In particular, it can be designed to develop a stronger damping effect with increasing relative speed between the striker and the drive shaft. Alternatively or additionally, it can be designed to develop stronger damping with increasing relative acceleration between the striker and the drive shaft. Alternatively or additionally, it is also conceivable for the shock absorber to have a variable, in particular adjustable, damping effect. It can, for example, comprise an electro- and / or magnetorheological fluid. The fluid can be dilatant. In general, the fluid can exhibit non-Newtonian behavior.

[0022] The shock absorber can have hydraulic and / or pneumatic components.

[0023] Further features and advantages of the invention will become apparent from the following detailed description of exemplary embodiments of the invention, based on the figures of the drawing, which illustrate details essential to the invention, and from the claims. The features shown therein are not necessarily to scale and are presented in such a way that the special features of the invention can be clearly seen. The various features can be implemented individually or in combinations in variants of the invention.

[0024] The schematic drawing shows embodiments of the invention and explains them in more detail in the following description.

[0025] They show:

[0026] Fig. 1 shows an impact wrench in a partially sectioned view; and

[0027] Fig. 2 is a sectional view of a rotary impact drive of the impact wrench according to Fig. 1.

[0028] In the following description of the figures, the same reference numerals are used for identical or functionally corresponding elements to facilitate understanding of the invention.

[0029] Fig. 1 shows an impact wrench 10 in a partially sectioned side view. A housing 12 is visible, from which a tool holder 14 protrudes. A handle area 16 with an operating element 18 is formed on the housing 12. The operating element 18 can be configured, for example, to switch the impact wrench 10 on and / or off and / or to regulate an operating parameter, such as a speed.

[0030] A battery pack 20 serves to supply power to the impact wrench 10. The battery pack 20 comprises lithium-containing batteries. The impact wrench 10 can thus be operated cordlessly. The battery pack 20 can have a capacity of at least 20 Wh. The battery pack 20 can be configured to provide an electrical power of at least 400 W, in particular as a peak power, for example, for up to 60 seconds, in particular 10 seconds.

[0031] The impact wrench 10 also has a rotary impact drive 22. The rotary impact drive 22 is arranged within the housing 12. It is shown in a partially sectioned view in areas II, III.

[0032] The operating element 18 can be arranged—as shown in Fig. 1—in a half of the handle area 16 facing away from the rotary impact drive 22. For this purpose, it can be arranged, for example, near the battery pack 20, for example, adjacent to a battery receptacle 24 for accommodating the battery pack 20. This arrangement of the operating element 18 can prompt a user of the impact wrench 10 to grip it in a low-vibration area. Thus, the user's exposure to vibrations can be further reduced.

[0033] Fig. 2 shows an enlarged view of area II, III from Fig. 1 showing details of the rotary impact drive 22.

[0034] The rotary impact drive 22 has a motor 25 that drives a drive shaft 28 via a gear 26, for example, a planetary gear. The drive shaft 28 defines a longitudinal axis L of the impact wrench 10 (see Fig. 1).

[0035] It drives a striker 30, which in turn strikes an anvil 32 with rotary strokes. In particular, the striker 30 can contact the anvil 32 along a circumferential direction U around the longitudinal axis L and, in particular, strike it. In Fig. 2, the circumferential direction U corresponds to a direction perpendicular to the image plane of Fig. 1 and is therefore depicted only symbolically in Fig. 2.

[0036] The anvil 32 is connected to the tool holder 14 (see Fig. 1) so that a tool arranged on the tool holder 14 can be driven, in particular in a rotary percussive manner.

[0037] The striker 30 is arranged to be displaceable along the drive shaft 28 and thus parallel to the longitudinal axis L. When the drive shaft 28 rotates about the longitudinal axis L, the striker 30 is driven forward in a longitudinal impact direction LR parallel to the longitudinal axis L, in particular toward the anvil 32 and thus toward the tool holder 14. A return spring 38 arranged between a rear section 36 of the drive shaft 28 and a rear side of the striker 30 is configured to return the striker 30 to an initial position, in particular opposite to the longitudinal impact direction LR, when the drive shaft 28 slows down or comes to a standstill.

[0038] In this embodiment, a shock absorber 40 is formed on the anvil 32. In particular, the shock absorber 40 is located between the striker 30 and the anvil 32. For this purpose, it is arranged on the anvil 32.

[0039] If the impact wrench 10 is put into operation, for example by means of the operating element 18 (see Fig. 1), the striker 30 is accelerated along the longitudinal impact direction LR.

[0040] In this case, particularly at high speeds of the striker 30 along the longitudinal direction LR, it may occur that the striker 30 strikes the anvil 32 along the longitudinal direction LR. However, such impacts or shocks are dampened by the shock absorber 40 located between them. Thus, vibrations due to such impacts along the longitudinal impact direction LR can be avoided or at least reduced.

[0041] The shock absorber 40 may comprise a plastic and / or a rubber-containing material, for example rubber.

[0042] If the striker 30 is driven back by the return spring 38, it may strike the rear section 36 with its rear side. To dampen such a shock, a recoil damper 42 is formed on the rear section 36. Thus, the rotary impact drive 22 has a further shock absorber—in the form of the recoil damper 42—which is designed to dampen a shock of the striker 30 in a longitudinal impact direction parallel to the longitudinal axis. The recoil damper 42 also contributes to reducing or completely avoiding unwanted vibrations.

[0043] Furthermore, the rotary impact drive 22 of the impact wrench 10 has a sliding damper 44. The sliding damper 44 is formed circumferentially on the drive shaft 28. It comprises a material with a higher coefficient of sliding friction than the adjacent drive shaft 28. If the impactor 30 thus enters the area of ​​the sliding damper 44, for example due to a correspondingly high speed in the longitudinal direction LR, the movement of the impactor 30 in the longitudinal direction LR is decelerated due to the increased coefficient of friction of the sliding damper 44. This also allows an impact of the impactor 30 along the longitudinal direction LR to be avoided or at least reduced, so that unwanted vibrations can also be avoided or at least reduced.

[0044] The shock absorber 40 and / or the recoil absorber 42 may comprise a plastic and / or a rubber-containing material, for example rubber.

[0045] In the embodiment of the impact wrench 10 shown here, the shock absorbers 40, the recoil absorber 42, and the sliding damper 44 are designed as passively acting elements. It is also conceivable that at least one of these elements 40, 42, 44 has at least one adjustable property, for example adjustable damping, an adjustable viscosity, for example electrically and / or magnetically, and / or an adjustable coefficient of friction. The element(s) with adjustable property can be connected to a control unit of the impact wrench 10. The control unit can be configured to adjust the adjustable property depending on a position, a speed, and / or an acceleration, in particular along the longitudinal direction L.

[0046] The embodiment of the impact wrench 10 shown here thus has a total of three shock absorbers, in particular the shock absorber 40, the recoil absorber 42, and the sliding damper 44. In alternative embodiments, only one or two of these shock absorbers or more than three shock absorbers may be provided.

[0047] List of reference symbols

[0048] 10 impact wrenches

[0049] 12 housings

[0050] 14 tool holders

[0051] 16 Grip area

[0052] 18 Control element

[0053] 20 battery pack

[0054] 22 Rotary impact drive

[0055] 24 recording

[0056] 25 engine

[0057] 26 gearboxes

[0058] 28 Drive shaft

[0059] 30 rackets

[0060] 32 anvil

[0061] Section 36

[0062] 38 Return spring

[0063] 40 shock absorbers

[0064] 42 recoil dampers

[0065] 44 sliding dampers

[0066] II, III area

[0067] L Longitudinal axis

[0068] LR longitudinal lay direction

[0069] U circumferential direction

Claims

Patent claims 1. Impact wrench (10) comprising a rotary impact drive (22), - wherein the rotary impact drive (22) has a drive shaft (28) extending along a longitudinal axis (L), wherein the rotary impact drive (22) has a beater (30) arranged to be displaceable along the longitudinal axis (L) and an anvil (32) which can be contacted by the beater (30) along a circumferential direction (U) to the longitudinal axis (L), and - wherein the rotary impact drive (22) has at least one shock absorber (40, 42, 44) which is arranged to dampen an impact of the beater (30) in a longitudinal impact direction (LR) parallel to the longitudinal axis (L), in particular on the anvil (32), - wherein the shock absorber (40) is formed between the beater (30) and the anvil (32), and / or - wherein the shock absorber (42, 44) is formed between the beater (30) and the drive shaft (28), and / or - wherein a recoil damper (42) is formed between a rear side of the stick (30) pointing against the longitudinal direction of impact (LR) and a recoil surface opposite the anvil (32) in the direction of impact (LR), limiting movement of the stick (30) along the longitudinal axis (L).

2. Impact wrench according to one of the preceding claims, characterized in that the shock absorber (40, 42, 44) comprises a plastic and / or a latex-containing material, for example a rubber-containing material, in particular rubber.

3. Impact wrench according to one of the preceding claims, characterized in that the shock absorber (40, 42, 44) comprises a fluid, in particular a liquid containing oil and / or water and / or a gas, in particular air.

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