EP0734814B1 - Hand-held machine tool, in particular impact wrench - Google Patents

Description

The invention relates to a hand tool, especially impact wrenches, with an engine, a Reduction gear and a pulse generator in one Housing, being used for damping by the Rotary pulse generator caused vibrations of the housing a spring means is provided.

Such a hand tool is in the DE 39 37 816 A1 described. The engine works through that Reduction gear on the rotary pulse generator, which for Intensification of the tightening moment abrupt angular momentum transfers to the screwing tool. These twists and turns result in unpleasant vibrations of the housing. Around dampening these vibrations is after the DE 39 37 816 A1 a torsion spring is provided.

The application of force to the torsion spring is constructive problematic. In addition, larger angles of rotation are the Torsion spring difficult to reach and kick it Vibration problems. In addition, the Torsion spring only when tightening the screw connection (Clockwise rotation), but not when loosening the screw connection (Counter clockwise rotation). It is destroyed in left-hand rotation.

The object of the invention is a hand tool of the type mentioned at the beginning, in which the Damping is improved in a structurally simple manner.

According to the invention, the above task is for a Hand tool of the type mentioned by the Features of the characterizing part of claim 1 solved.

In the event of a rotary impact, the ring will Bearing on the helix moved axially parallel. Thereby the spring tensions axially. After the shot the spring relaxes. This ensures that none Torsion spring is necessary. Preferably one coiled compression spring inserted. It could also be one Tension spring can be used.

The device described dampens the vibrations effective and reduces noise. By dimensioning the pitch of the helix, one can achieve large rotation angles for a desired damping. It is also convenient that a small for the establishment Installation space in the housing is sufficient.

The ring is preferably with its inner circumference on the Helix led to the outside of the rotary knock exposed part is attached. The ring is then on its outer circumference on a housing-fixed guide axially slidably guided. But it would be that too reverse arrangement possible in which the helix is formed fixed to the housing and the ring on one Part exposed to torsional impact is axially displaceable and non-rotatable is led.

In a preferred embodiment of the invention is the ring stored on the helix by means of balls. There occur correspondingly low frictional forces between the ring and the coil on. If higher friction forces Support damping and / or another Simplification of construction are desired, the ring can with one or more formations formed on it engage in the helix.

The spring mentioned is in clockwise rotation, i.e. when tightening the screw connection, tensioned. In the design of the Invention is for damping shocks in left-hand rotation (Loosen the screw connection) the ring on its the Spring opposite end face another Damping element assigned. This can be an easy one Elastomer body or to improve damping in the Counterclockwise rotation can be another coiled compression spring.

Figur 1 einen Akku-Schlagschrauber im Schnitt,

Figur 2 eine gegenüber Fig. 1 vergrößerte Teilansicht,

Figur 3 eine Wendel an einem Hohlrad des Getriebes in perspektivischer Teilansicht,

Figur 4 ein weiteres Ausführungsbeispiel in einer im wesentlichen Fig. 2 entsprechenden Darstellung und

Figur 5 ein weiteres Ausführungsbeispiel.

Further advantageous refinements of the invention result from the subclaims and the following description of exemplary embodiments. The drawing shows:

FIG. 1 shows a cordless impact wrench in section,

FIG. 2 shows a partial view enlarged compared to FIG. 1,

FIG. 3 shows a helix on a ring gear of the transmission in a partial perspective view,

Figure 4 shows another embodiment in a representation corresponding essentially to Fig. 2 and

Figure 5 shows another embodiment.

An impact wrench has a handle housing part (1) and a drive housing part (2) in which a motor (3), a Planetary gear (4) and a pulse generator (5) are arranged. The motor (3) drives over it Planetary gear (4) as a reduction gear Rotary pulse generator (5), which in turn has a shaft (6) drives on which a not shown Screwing tool is attachable. The common axis of the Drive unit is labeled (A).

The motor (3) is an electric motor from a battery pack (7) operable. It could also be network operated or else be an air motor. The rotary pulse generator (5) is one known, commercially available unit.

The planetary gear (4) has a gear housing (8), which is fastened in the drive housing part (2). With the Gear housing (8) is a carrier (9) on the one hand screwed, on which the motor (3) is held. On the other hand with the gear housing (8) Screwed cover (10), in the embodiment according to Figures 1 to 4 of the rotary pulse generator (5) stored is.

A pinion (12) of the motor (3) meshes with planet gears (13) of the planetary gear (4), of which in Figures 2 and 4 one is shown. The planet gear (13) is on one Axle piece (14) mounted in a planetary web (15) to drive the rotary pulse generator (5). Of the Planetary web (15) is on by means of a ball bearing (16) Gearbox housing (8) mounted.

The planetary gear (4) has one with a Internal gear (17) provided ring gear (18). With the Internal teeth (17) mesh the planet gears (13). Between the ring gear (18) and the carrier (9) is a another ball bearing (19) arranged.

In the embodiment according to Figures 2 and 4 that is The ring gear (18) is provided on the outside with a helix (20) runs parallel to the axis of rotation (A) and from one groove-shaped depression is formed. The spiral (20) a ring (21) is assigned. This stands by means of a or more balls (22) with the helix (20) in Connection. In Figures 2 and 4 is a ball (22) shown. Preferably three or more balls distributed on the inner circumference of the ring (21). are For example, three balls (22) are provided, then the Provide the helix (20) with three parallel gears. are For example, several balls (22) are provided provide the helix (20) with several parallel gears. The balls (22) are arranged in a cage (23) they on the outer circumference of the ring gear (18) or The inner circumference of the ring (21) is provided in a distributed position maintained. It would also be possible to use several balls (22) only one single helix (20) to provide. The ball receiving groove (24) of the ring (21) would then have a slope equal to the helix (20) exhibit.

The ring (21) is with its outer circumference (25), for example by means of a nose (26) on one to the axis (A) parallel longitudinal guide slot (27) of the Gear housing (8) rotatably, but axially displaceable guided. A compression spring (28) is supported on the ring (21) one end (29). The other end (30) of the Compression spring (28) is supported on the gear housing (8).

The operation of the device described is in essentially the following:

In operating phases in which the rotary shock does not exceed the Planetary web (15) and the planet gears (13) on the Reacts ring gear (18), the ring gear (18) is relative blocked because of the balls (22) with the Helix (20) related ring (21) under the The compression spring (28) is preloaded. This position of the Ring (21) and the compression spring (28) is above in Fig. 2 the axis (A).

Occurs as a result of a vigorous spin correspondingly higher kickback torque on the Ring gear (18), then this rotates about the axis (A) and takes the ring (21) with it via the balls (22), wherein the latter tensions the compression spring (28). The one there resulting angle of rotation of the ring gear (18) depends on the Slope of the helix (20) and the spring characteristic of the Compression spring (28). This ensures that Vibrations caused by pressure shock compared to the Gear housing (8) and thus also the drive housing part (2) and the handle housing part (1) are damped so that no annoying vibrations or noise occur. Since the helix (20) is about much more than 360 ° are in coordination with the characteristic the compression spring (28) achieves good damping values. A Position in which the ring (21) due to a Rotation of the ring gear (18) has shifted axially parallel and the compression spring (28) has been further stretched is in Fig. 2 shown below the axis (A).

The compression spring relaxes after a rotary impact tip (28) and turns it over the ring (21) and the balls (22) Ring gear (18) back, the in the compression spring (28) stored energy via the planetary gear (4) and the Rotary pulse generator (5) on the screwing tool, the Torque support, reacts.

The function explained above with reference to FIG. 2 relates the case of tightening a screw (clockwise rotation). Becomes loosened a screw, then also strong Rotary impact peaks occur which lead to vibrations can. To dampen this, the execution is after 2 in the carrier (9) a resilient or rubber-elastic body, for example an elastomer ring (31), arranged by a ring (21) facing Socket (32) is covered. In the event of a spin in the The ring (21) hits the bushing (32) and counterclockwise thus the elastomer ring (31) so that it also runs counterclockwise damping takes place.

4 is instead of Elastomer rings (31) another compression spring (33) between the carrier (9) and the ring (21) arranged. The spring (33) acts in counterclockwise rotation just like the spring (28) in Clockwise rotation. Turns counter-clockwise with a rotary impact tip the ring gear (18) and takes over the balls (22) the ring (21) with the further compression spring (33) tense.

5, the helix (20) on the jacket (11) of the rotary pulse generator (5) and not on the Ring gear (18) is formed, the rotationally fixed in the housing (8) is arranged. Parts corresponding to Figures 2 and 4 are provided with the same reference numerals in FIG. 5. The Rotational shocks described above also act on the jacket (11) of the pulse generator (5). They are in effect on the housing in the embodiment of FIG. 5 by the Damped ring (21), which via balls (22) into the coil (20) engages and in longitudinal guide slots (27) one Inner part (34) can be moved parallel to axis (A) is led. The ring (21) is on both sides as in Fig. 4 supported by compression springs (28,33).

This sits on the planetary web (15) in a rotationally fixed manner Inner part (34). The planetary web (15) and the inner part (34) could be formed in one piece. The ring (21) transfers the rotary motion of the planetary web (15) to the Jacket (11) of the rotary pulse generator (5), the shaft (35) at Fig. 5 is rotatably mounted in the planetary web (15). If it bothers that the spring (28) on the one hand rotating Ring (21) and on the other hand on the non-rotating housing (8) a bearing can be provided, the ensures that the spring (28) rotates at both ends or is non-rotatable.

Claims (14)

1. Hand-held machine tool, in particular impact screwdriver, comprising a motor 93], a reducing gear unit [4] and a rotary pulse generator [5] in a housing [2], wherein for damping of the vibrations of the housing caused by the rotary pulse generator [5] a suspension means [28] is provided, characterised in that the one end of the spring [28] is supported on a ring [21], which is on the one hand mounted with a helix [20] extending parallel to the axis of rotation on a part [18; 11] of the machine exposed to the rotary impact, and on the other hand is guided displaceably parallel to the axis, and in that the other end of the spring [28] is supported on a part [8; 10] integral with the housing, so that the spring [28] is braced axially upon rotary impact.
2. Hand-held machine tool according to claim 1, characterised in that the spring is a coiled pressure spring [28] or a tension spring.
3. Hand-held machine tool according to claim 1 or 2, characterised in that the ring [21] is guided so as to be displaceable parallel to the axis between a part [8] integral with the housing and a part [18] and a part [18] exposed to the rotary impact.
4. Hand-held machine tool according to one of the preceding claims, characterised in that the ring [21] is guided with its inner circumference on the helix [20], which is provided on the exterior on a part [18; 11] exposed to the rotary impact.
5. Hand-held machine tool according to one of the preceding claims, characterised in that the ring [21] is non-rotatably, axially displaceably guided at its outer circumference in a guide [27] integral with the housing.
6. Hand-held machine tool according to claim 5, characterised in that the helix [20] is provided on the exterior of the hollow wheel [18] of the reducing gear unit formed by a planetary gear unit [4].
7. Hand-held machine tool according to claim 4, characterised in that the helix [20] is provided on the exterior surface [11] of the rotary pulse generator [5].
8. Hand-held machine tool according to one of the preceding claims, characterised in that the ring [21] is supported at least by means of a ball [22] on the helix [20].
9. Hand-held machine tool according to claim 8, characterised in that the balls [22] are held spaced apart in a cage at the circumference of the ring [21].
10. Hand-held machine tool according to claim 8 or 9, characterised in that the helix [20] is multi-threaded according to the number of balls [22].
11. Hand-held machine tool according to one of the preceding claims, characterised in that the spring [28] in the relaxed state has a bias which holds blocked the part [18; 11] exposed to rotary impact relative to the part [8; 34] on which the ring [21] is displaceably guided parallel to the axis, unless a particular rotary impact moment occurs.
12. Hand-held machine tool according to one of the preceding claims, characterised in that the spring [28] is stressed in clockwise running and in that in order to damp rotary impacts in anti-clockwise running the ring [21] is associated with a further damping element [31; 33] on its end face opposite the spring [28].
13. Hand-held machine tool according to claim 12, characterised in that the further damping element is a spring-resilient body, in particular an elastomer body [31].
14. Hand-held machine tool according to claim 12, characterised in that the further damping element is a further coiled pressure spring [33].

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