WO2008116691A1

WO2008116691A1 - Rotary percussion mechanism

Info

Publication number: WO2008116691A1
Application number: PCT/EP2008/051509
Authority: WO
Inventors: Aldo Di Nicolantonio
Original assignee: Robert Bosch Gmbh
Priority date: 2007-03-28
Filing date: 2008-02-07
Publication date: 2008-10-02
Also published as: EP2132005B1; EP2132005A1; ES2382497T3; DE102007014757A1; ATE555880T1

Abstract

The invention relates to a rotary percussion mechanism (1) for an electric tool, having a drivable rotary percussion weight (3) with at least one hammer surface (15), and having an anvil (16) that can be rotated with the rotary percussion weight (3) about a common rotational axis (13) and is operatively connected to a tool shaft (2) to transmit torque, said anvil having at least one anvil surface (16). Said rotary percussion mechanism also has a displacement mechanism comprising a return spring (9), said mechanism being designed to cause a combined relative motion in the axial and circumferential directions under tension of the return spring (9) between the rotary percussion weight (3) and the anvil (10), resulting in a percussion effect of the hammer surface (15) on the anvil surface (16) in the circumferential direction, when the tool shaft (2) demands increased torque. According to the invention, the tool shaft (2) is axially displaceably supported, and the anvil surface (16) and/or the hammer surface (15) is/are aligned and/or designed such that a percussion of the hammer surface (15) on the anvil surface (16) results in a displacement of the tool shaft (2) in the axial direction, in addition to a rotary impulse on the tool shaft (2) in the circumferential direction.

Description

description

Rotary percussion

State of the art

The invention relates to a rotary impact mechanism for an electric tool, in particular an electric hand tool according to the preamble of claim 1.

Such rotary impact devices are used exclusively in helicopters and rotary impact wrenches (impact wrenches). An example of a rotary impact wrench with a rotary impact mechanism is disclosed in DE 147 88 09. With rotary impact drives, a distinction is made between three basic types, namely cam followers, V-groove impactors and hydraulic pulse impactors. Rotary tappets enable the release of high torques with relatively low power input in almost torque-free manner. Furthermore, they are characterized by the fact that they convert the continuous power output of the drive motor in a punch-shaped angular momentum, the energy output of the engine is stored in a rotational impact weight and abruptly transmitted by means of a pulse of high power intensity on a non-rotatably mounted on a tool shaft supporting a screwing anvil , Another advantage of rotary impact is that they are compact and inexpensive to produce.

Impact drills usually use detent impact devices, which in contrast to the rotary impact mechanism do not produce any angular momentum in the circumferential direction on the tool shaft. conditions, but only an adjustment pulse in the axial direction. Rastenschlagwerke have the advantage that they are extremely simple and inexpensive to produce. In practice, however, these prove to be less effective (low impact). More powerful mechanical percussion for impact drills, for example, so-called mass impact, the structure of which is very complex and they are therefore expensive to produce and assemble.

DISCLOSURE OF THE INVENTION Technical Problem

The invention is therefore based on the object to modify a rotary striking mechanism for use in a percussion drill.

Technical solution

This object is achieved with the features of claim 1. Advantageous developments of the invention are specified in the subclaims. All combinations of at least two of the features specified in the description, the claims and / or the figures also fall within the scope of the invention.

The invention is based on the idea of aligning or shaping the at least one hammer surface and / or the at least one anvil surface in such a way that a force component acting on the tool shaft in the axial direction is generated by the impact of the hammer surface on the anvil surface in addition to the angular momentum in the circumferential direction will, which ensures that the adjustable in the axial direction stored tool shaft, which preferably carries a drill chuck with drilling tool, is accelerated in the direction of the workpiece to be machined. As a result of this modification compared with known rotary impact devices, the rotary impact mechanism according to the invention can be used to produce a striking drill driver. The rotational energy of the rotational impact weight is used, inter alia, for generating the axial force component. The preferred oblique or curved alignment or shaping of the hammer surface and / or the anvil surface thereby ensures a division of the angular momentum into an axial and a peripheral component. The rotary impact mechanism according to the invention is extremely powerful and requires little space. In addition, the rotary impact is inexpensive to produce. The claimed Drehschlagwerk can cover even without a gear ratio to cover a large speed range with high torque and works efficiently and kickback, even in hard building materials such as concrete or rock. The drilling action is supported in addition to the axial impact of the impact component acting in the circumferential direction.

The rotary impact mechanism can be formed with all known adjustment mechanisms, such as a cam mechanism, a Schrägnuten mechanism, in particular a V-groove mechanism, or a particular hydraulic pulse mechanism.

An advantage is an embodiment in which, with an increased torque requirement by the tool or by the tool shaft and an associated reduction in rotational speed of the tool shaft by means of an adjustment mechanism, a relative movement between the rotary shaft impact weight and the anvil, which is preferably permanently coupled torque-transmitting with the tool shaft, in particular rotatably connected thereto, effected in the axial and circumferential direction, whereby from the rotational movement of the rotational impact weight out a collision between the hammer surface and the anvil surface is provoked. Preferably, the tool shaft is axially adjustable in such a way, in particular between two axial stops, that an axial displacement of the tool results by at least two, preferably at least three, in particular at least five millimeters, or more.

In an embodiment of the invention is advantageously provided that the axial force component is achieved on the tool shaft by the fact that the hammer surface with an imaginary, orthogonal to the axis of rotation of the tool shaft and the rotary impact weight, in particular by the anvil, extending plane an angle α ≠ 90th ° is clamped. By selecting the angle α, the ratio between the angular momentum and the axial momentum can be set.

Additionally or alternatively, it is provided in a development of the invention that the anvil surface is inclined relative to the orthogonal to the axis of rotation plane at an angle ß ≠ 90 °, ie with this plane an angle ß ≠ 90 °.

To minimize the wear of the hammer surface and the anvil surface, it is advantageous if the angular relationship

α = 180 ° -β

applies. In addition to a planar design of the anvil surface and / or the hammer surface and a curved training is conceivable, preferably the hammer surface and the corresponding anvil surface are curved in the same direction and with the same radius of curvature, that are at least approximately formed congruent.

It has proven to be advantageous if the angle α at least approximately from an angular range between 5 ° and 85 °, in particular at least approximately between 15 ° and 75 °, preferably at least approximately between 25 ° and 65 °, preferably between 35 ° and 55 ° is selected, or more preferably about 45 °. At an angle α of 45 ° while the impact energy is at least approximately split in half to generate a shock pulse in the axial direction and to generate a shock pulse in the circumferential direction. The angle β is preferably 180 ° - α.

In order to increase the impact frequency, it is advantageously provided that the anvil has a plurality of anvil surfaces inclined in the same direction and / or the rotational impact weight has a plurality of hammer surfaces inclined in the same direction.

In order to realize a hammering action in the axial direction, ie a shock pulse on the tool shaft in the axial direction, both in a rotational speed driven in a left direction of rotation as well as a driven in a right direction of rotation rotational impact, it is advantageous if the anvil at least two in opposing directions inclined anvil surfaces and / or the rotational impact weight at least two in opposite set directions has inclined hammer surfaces. Preferably, both mutually oppositely inclined anvil surfaces and both mutually oppositely inclined hammer surfaces are each at an axial projection of the anvil and the rotational impact weight.

In order to be able to vary the ratio between the axial impact pulse and the peripheral impact pulse, it is advantageous if at least one adjusting mechanism is provided for varying the angle α or the angle β. Preferably, this adjustment mechanism is designed such that an angle α and / or an angle ß of at least approximately 90 ° is adjustable, so that no axial impact pulse results on the tool shaft and equipped with the rotary percussion power tool can be used as a rotary impact wrench.

Advantageously, another embodiment of the rotary impact mechanism, in which the adjusting mechanism can be blocked or bridged, preferably such that at an increased torque request by the tool shaft no impact pulse is triggered. With this development, it is possible to use a power tool equipped with the rotary impact mechanism in the pure drilling operation (pure rotary operation) without hammer operation.

Advantageous is a construction in which the tool shaft, in particular together with the anvil by means of a spring, in particular designed as a helical spring in the direction of an axial stop is subjected to spring force, wherein the axial stop is preferably arranged at the opposite end of the free end of the tool shaft. The spring serves as a return spring for adjusting the tool shaft to its starting position after full axial movement.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings; these show in:

Fig. 1 is a solely for the clockwise rotation configurable tes rotary impact mechanism with a trained as Nockenmechanis ^¬ adjusting mechanism in a position at the beginning of an increased torque demand by a tool shaft,

1 in a position in which the rotational impact weight with its hammer surface a stroke in the circumferential direction against an anvil surface of rotatably connected to the work ^¬ generating shaft anvil exerts, and

Fig. 3 is a schematic representation of essential components of a rotary impact mechanism, which can perform both a left and a right direction of rotation rotational shocks with an axial force component.

Embodiments of the invention

In the figures, the same components and components with the same function with the same reference numerals. In the figures, designed as a cam impact turning device is shown. Alternatively, the rotary impact mechanism can also be designed as Schrägnuten-, in particular V-Nutenschlagwerk, or as a pulse impact mechanism. Further control or adjustment mechanisms are also conceivable. The formation of the rotary impact mechanism as a V-groove impact mechanism would have the advantage that the energy stored in the rotational impact weight can accelerate quasi-free from the drive motor by a spring in the wire direction. In a cam follower described by way of example below, part of the stored energy is used to accelerate the drive motor.

The rotary impact mechanism 1 shown in FIG. 1 comprises a tool shaft 2, at the upper, free end of the drawing plane, for example, a drill chuck with a drill tool is arranged. Coaxially with a camshaft 19 which is aligned with the tool shaft 2 and is positively connected with the tool shaft 2, a rotary impact weight 3 is arranged which is provided with an outer longitudinal toothing 4. By means of a drive motor, not shown, whose motor shaft is formed with a longitudinal toothing 4 conforming to the longitudinal toothing, which is engaged with the longitudinal teeth 4 of the rotary impact weight 3 (not shown), the rotational impact weight 3 in the direction of arrow 5 (left-handed) driven.

A cam disc 6 with cam 7 sits on the camshaft 18 in a rotationally fixed manner. The rotational impact weight 3 is supported on the cam disc 6 by a ball 8, the rotational impact weight 3 being actuated by means of a restoring spring 9, which is rotationally fixed on the tool shaft 2 arranged anvil 10 (anvil disk) and the other end at one Ring shoulder 11 of the rotary impact weight 3 is supported in the axial direction on the cam 6 spring force.

As long as the tool shaft 2 (with drilling tool) offers no major resistance, the biasing force of the return spring 9 is sufficient that the rotary impact weight 3 on the ball 8, the cam 6 and thus the camshaft 18 and thus the tool shaft 2 rotates in the direction of arrow 12 (left-hand rotation ). Rotational impact weight 3, tool shaft 2 and camshaft 18 rotate about a common axis of rotation 13.

Increases the resistance during drilling, so increases the torque requirement of the tool shaft 2, then reduces the rotational speed of the tool shaft 2 and due to the positive connection with the camshaft 18, and the rotational speed of the camshaft 18, thereby possibly even come to a standstill. The driven, further rotating rotational impact weight 3 is pressed by rolling the ball 8 via the cam 7 against the spring force of the return spring 9 on the camshaft 18 forward in the direction of arrow 19. When the ball 8 reaches the front edge 14 of the cam 7, an oblique hammer surface 15 of the rotary impact weight 3 strikes an anvil surface 16 of the anvil 10. The hammer surface 15 is approximately 45 ° relative to a plane E orthogonal to the axis of rotation 13 and through the anvil 10 ° inclined. The anvil surface encloses with the plane E an angle ß = 180 ° - 45 ° = 135 °. Due to the inclination of the surfaces 15, 16, the anvil 10 and thus the tool shaft 2 undergoes not only an angular momentum in the circumferential direction (arrows 5, 12), but also in the axial direction 17, whereby the tool shaft 2 in the axial direction 17 is adjusted and thus an axial impact is exerted on the workpiece to be machined.

The positive connection between the camshaft 18 and the tool shaft 2 is preferably formed such that the positive engagement in the axial movement of the tool shaft 2 and the axially differently mounted camshaft 18 does not solve.

After a completed blow the rotational impact weight 3 and the ball 8 are pushed back by the return spring 9 on the back 20 of the cam 7 on the cam 6 of the camshaft 18, so that the hammer surface 15 can rotate past the anvil surface 16 past. After one revolution (in the case of a single-cam impact mechanism), the rotary impact weight 3 hits the cam 7 of the camshaft 18 again by means of its ball 8, as a result of which the sequence described is repeated.

In Fig. 2 it is shown how the inclined at an angle α of about 45 ° to the plane E hammer surface 15 and the plane E at an angle ß of about 135 ° inclined anvil surface 16 abut each other.

In Fig. 3, only a section of the tool shaft 2 with anvil 10 and a section of the rotary impact weight 3 is shown. It can be seen that the rotational impact weight 3 has two mutually oppositely inclined hammer surfaces 15, both of which enclose with the plane E an angle α of about 65 °. Accordingly, the anvil 10 is provided with two mutually oppositely inclined hammer surfaces 16 which each span with the plane E an angle ß of about 115 °. The angular relationship α = 180 ° - ß applies here. The rotary impact mechanism 1 shown can both left and also an anti-clockwise axial impact pulse to the tool shaft 2 generating operated.

Claims

claims

1. Rotary impact mechanism for a power tool, with a drivable rotary impact weight (3) with at least one hammer surface (15), and with the Drehschlaggewicht (3) about a common axis of rotation (13) rotatable and with a tool shaft (2) operatively operatively connected torque Anvil (10) having at least one anvil surface (16) on which the hammer surface (15) is arranged to act in the circumferential direction, characterized in that the tool shaft (2) is mounted axially adjustable, and that the anvil surface (15) and / or the hammer surface (16) are aligned and / or formed such that a displacement of the hammer surface (15) on the anvil surface (16) in addition to an angular momentum on the tool shaft (2) in the circumferential direction a displacement of the tool shaft ( 2) in the axial direction (17) results.

2. Rotary impact mechanism according to claim 1, characterized in that the rotary impact mechanism (1) having a return spring (9) having adjusting mechanism is provided at an increased torque requirement of the tool shaft (2) under tension of the return spring (9) between the rotational impact weight (3 ) and the anvil (10) a combined relative movement in the axial and in the circumferential direction and in consequence the impact of the hammer surface (15) in the circumferential direction on the anvil surface (16) is formed effecting.

3. Rotary impact mechanism according to one of claims 1 or 2, characterized in that the anvil surface (15) relative to a plane orthogonal to the rotation axis (13) extending plane (E) at an angle (α) of not equal to 90 ° inclined.

4. Rotary impact mechanism according to one of claims 1 to 3, characterized in that the anvil surface (16) with respect to the orthogonal to the axis of rotation (13) extending plane (E) at an angle (ß) of not equal to 90 ° inclined.

5. Rotary impact mechanism according to claim 4, characterized in that at least approximately α = 180 ° - ß.

6. Rotary impact mechanism according to one of the preceding claims, characterized in that the angle α between the hammer surface (15) and the orthogonal to the axis of rotation (13) extending plane (E) at least approximately between 5 ° and 85 °, in particular at least approximately between 15 ° and 75 °, preferably at least approximately between 25 ° and 65 °, preferably between 35 ° and 55 °, more preferably about 45 °.

7. Rotary impact mechanism according to one of the preceding claims, characterized in that the angle (ß) between the anvil surface (16) and the orthogonal to the rotation axis (13) extending plane (E) at least approximately between 95 ° and 175 °, in particular at least approximately between 105 ° and 165 °, preferably at least approximately between 115 ° and 155 °, preferably between 125 ° and 145 °, particularly preferably about 135 °.

8. Rotary impact mechanism according to one of the preceding claims, characterized in that the anvil (10) has a plurality of inclined in the same direction anvil surfaces (16) and / or the rotary impact weight (3) a plurality of inclined in the same direction hammer surfaces (15).

9. Rotary impact mechanism according to one of the preceding claims, characterized in that the anvil (10) at least two inclined in opposite directions anvil surfaces (16) and / or the rotary impact weight (3) at least two in opposite directions inclined hammer surfaces (15) having.

10. rotary impact mechanism according to one of claims 3 to 9, characterized in that the angle (α) and / or the angle (ß) are adjustable by means of an adjusting / is.

11. Rotary impact mechanism according to one of claims 2 to 10, characterized in that a blocking device for override and / or a bridging device is provided for bridging the adjusting mechanism.

12. Rotary impact mechanism according to one of the preceding claims, characterized in that the tool shaft (2) by means of a spring in the direction of a camshaft (18) is spring-loaded.