JPS582796B2 - Shuyougeki driver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an impact driver with a pressure medium-driven motor, in which a preset predetermined starting torque is achieved by an impact movement of the hammer of the impact driver. of the type that is interrupted by a device controlled by a pulsed pulse.

In known percussion drivers of this type, the axial movement produced by the percussion tool during an impact is transmitted to a shaft provided with a freewheeling device.

To the extent that such a shaft is rotated by a predetermined amount, the shaft releases a device that disconnects the pneumatic drive motor of the percussion driver.

Such mechanically actuated devices in known percussion drivers consist of a large number of parts, some of which are quite complex.

They are therefore difficult to maintain and prone to failure, which is particularly a problem when impact drivers are driven roughly.

Furthermore, the known device is very expensive due to its complex construction.

The object of the present invention is to shut off after performing a predetermined number of impacts,
The object of the present invention is to provide an impact driver of the type described above which is easily constructed and reliably operated.

In order to solve such a problem, in the configuration of the present invention, the compressed air passage to the control pressure chamber leading to the control passage is opened in a pulsating manner by the impact of the hammer, and one wall of the control pressure chamber is connected to the motor. is formed by the piston of the closing valve for interrupting the pressure medium flow leading to the valve, and is provided with a return spring for holding the closing valve in the open position of the pressure medium flow path; The spring force of is designed such that it is overcome by the pressure of compressed air which is collected in said control pressure chamber by pulsating supply up to a predetermined limit value, so that the closing valve is able to control the pressure medium leading to the motor. The control pressure chamber is moved to a closed position of the flow path, and the control pressure chamber is connected to a ventilation device.

The isolation device for the motor of a percussion driver is simple in construction and robust to drive.

A particularly simple embodiment of the invention is obtained in which the control valve has a plate-like valve actuated by a push rod which transmits the axial movement of the hammer.

Particularly advantageously, the push rod is fixed to the hammer concentrically with respect to the axis of rotation, and the length of the push rod is such that the valve member is held in the closed position in such a way that the hammer is not impacted. It is good to have

The invention will be explained below with reference to the exemplary embodiments shown.

The percussion driver has an approximately cylindrical housing 1, on which a housing projection, which projects downward and is designed as a hand grip 2, is supported approximately in its central region.

In the central region, a compressed air-driven vane motor (not shown) is arranged in the housing 1 of the percussion driver as the drive of this percussion driver.

A percussion tool is provided in the front part of the casing, and a control device is arranged in the rear part 4, by means of which the vane motor is switched off as soon as a predetermined starting torque has been achieved. Ru.

The impact tool 3 placed in the front part of the impact driver is
It has a hammer guide casing 5 which is non-rotatably connected to the drive of the vane mortar and is supported in the housing 1 via a needle bearing 6.

The hammer guide casing is cup-shaped,
An internal gear 7 is provided on the inner wall of the hammer guide casing and extends parallel to the axis.

A hammer 9, which is an impact tool provided on an external gear 8 assigned to the internal gear 7, is arranged movably in the axial direction, and an impact cam 10 is provided on the front side of the hammer 9. This impact cam 10 then strikes the corresponding cam 11 of the impact body 12 at the impact position of the hammer.

At the front end of the hammer, the percussion body 12 transitions into a tool head 13 projecting from the casing 1 of the percussion driver, into which a corresponding tool approximately configured as a box spanner is mounted. I can do it.

Impact tool 3 composed of a hammer 9 and an impact body 12
A camshaft 14 is arranged concentrically with respect to the impact body 12 and is non-rotatably connected to the impact body 12, which camshaft has a cam-like rising sliding surface 16 for the ball 17 on the collar 15. are doing.

The ball 17 is guided in a recess provided for the ball on the end side of the hammer towards the collar 15.

On the side opposite the sliding surface 16 of the hammer, a collar 15 is supported on the bottom of the hammer guide casing 5 via a thrust bearing (not shown).

A compression spring 18 is arranged in a chamber provided around the camshaft 14, and this compression spring has one side connected to the impact body 12.
and is supported on the other side by a friction disk 19 located within the hammer 9.

The compression spring 18 holds the hammer 9 in such a position that the impact cam 10 does not strike the cam 11 assigned to it.

A push rod 21 is arranged in a concentric bore 20 of the camshaft 14, which extends to the rear part 4 of the impact driver.

A push rod 21 is connected to the friction disk 19 via a pin 23 extending outwardly through a longitudinal slot 22 of the camshaft 14, so that the axial movement of the hammer 9 is controlled by the push rod 21.
is transmitted to the hitting ball.

The hand grip 2 supplies compressed air to the vane motor.
This is achieved via a switch valve which is arranged in a housing projection designed as a casing, of which only the actuating button 24 is shown in the drawing.

Via a known reversing valve (not described) the compressed air is reversed so that the motor is driven to the left or to the right.

A closing valve 27 in the passage 26 leading to compressed air flow to the motor.
is arranged, and this closing valve can shut off the compressed air flow.

A compression spring 28 holds the closure valve in the open compressed air flow path position shown in FIG.

A closing valve 27 is disposed in the guide hole 30 so as to be movable in the longitudinal direction, and a piston 29 is supported at the end opposite the compression spring 28 , which piston 29 is disposed in the guide hole 30 . Guided within the expanded range.

The guide hole 30 is closed to the outside by a screw cap 31.

Located in front of the piston 29, a control passage 32 opens into the control pressure chamber in the enlarged part of the guide hole 30, this control passage coming from a control valve 33 (FIG. 3).
.

The control passage 32 is ventilated with outside air via a vent hole 34 which is kept closed by a closure member 35 .

The closing member 35 is configured as a piston that is loaded into the passage 26 by the drive pressure of the compressed air flow to the monitor of the percussion driver.

That is, the vent 34 is closed in such a way that there is a flow of compressed air to the motor of the impact driver.

The control valve 33 has a plate-shaped valve member 36 which is actuated by the push rod 21 transmitting the axial movement of the hammer 9.

The length of the gap push rod 21 is determined so that the valve member 36 is held in the closed position in the gap where it is not affected by the hammer 9.

In such a closed position, the supply hole 37 and the discharge hole 38 forming the compressed air passage of the control valve are separated.

The supply hole 37 is supplied with a flow of compressed air coming from a switch valve operated by the operating button 24 via a passage 39 .

An outlet 38 is connected to the control passage 32 .

A throttle valve 40 is arranged in the control channel 32 which guides the control pulses produced by the control valve 33.

The throttle valve 40 is designed as a needle valve and is arranged in a pivot sleeve 41 .

With the pivot sleeve in the position shown in Figure 3,
A control pulse generated by control valve 33 can reach throttle valve 40 .

The rotation of the rotation sleeve 41 is adjusted by the locking ball 42 at such a position.

When the pivot sleeve is in another position, such as that provided via the notched adjustment button 43, the control passage 32 is interrupted.

The throttling action of the throttle valve can be changed by rotating the adjustment button 44.

By turning the adjustment button 44, the conically shaped 21 dollar of the throttle valve is screwed into or out of the throttle position, thereby changing the throttle gap width.

The operation of impact tools is generally considered to be well known and will therefore be briefly explained here.

As the drive motor rotates, the hammer guide casing 5 and the hammer 9 are rotated.

Through frictional contact, via the ball 17 and the sliding surface 16,
A camshaft 14, which is non-rotatably connected to the impact body, is entrained.

At the same time, however, the compression spring 18 also transmits a component of the torque to the impact body 12 .

This causes the impact body to rotate together with the hammer.

The impact body 12 is applied from the outside in such a way that it is resisted by a screwed nut, so that the frictional connection between the hammer and the impact body is overcome, so that the hammer is able to connect with the impact body and this impact. A relative rotation is performed with respect to a camshaft coupled to the body.

This spacing ball 17 rolls on a cam-like rising sliding surface 16, and it moves the hammer axially into the impact position in which it is successively struck by the impact cams 10.11.

However, since the sliding surface 16 is lowered again, the percussion cam can immediately be released again and thus returned to the initial working process.

The percussion tool strikes until the rotational resistance exerted on the impact body from the outside is overcome or until the percussion tool is switched off.

To avoid over-tightening the nuts that are nearly screwed down by the impact driver, the impact driver
It is automatically switched off after a predetermined torque has been obtained.

This occurs as follows. Each time the hammer 9 strikes, the push rod 21 opens the control valve 33 for a short time, so that a predetermined amount of compressed air (control pulse) reaches the control channel 32.

As soon as a pressure is built up in the control pressure chamber located in front of the piston 29 of the closing valve 27 to overcome the force of the compression spring 28, the closing valve 27 is in a position where it closes off the compressed air flow to the motor of the percussion driver. as a result of which the motor is stopped.

Due to the pressure relief now created in the channel 26, the closing member 35 opens the vent 34, so that the pressure medium present in the control channel can escape via the vent 34.

If the closing valve is then moved back into the starting position by means of the compression spring 28, the mechanism is once again ready for a new screwing operation.

How many pulses, i.e. impacts of the percussion tool, are required until the magnitude of the pressure prevailing in the control pressure chamber located in front of the piston 29 is sufficient to displace the closing valve? Adjustment can be made with the adjustment button 44.

With the help of the adjustment button 43, the pivoting sleeve 41 is
For example, it is rotated to a position where the control passage 32 is cut off in a position where automatic cut-off of the impact driver is not desired upon unscrewing.

Of course, in addition to the adjustment described here, it is also possible to vary the force of the compression spring 28 via the throttle valve 40.

[Brief explanation of the drawing]

Figure 1 is a partial longitudinal sectional view of the impact driver, Figure 2 is an enlarged end view of the impact driver on the side opposite to the tool head, and Figure 3 is a partial longitudinal sectional view of the impact driver.
The figure is a vertical cross-sectional view taken along the line ■-■ in Figure 2, and Figure 4 is a
It is a longitudinal cross-sectional view along the line ■-■ in the figure. DESCRIPTION OF SYMBOLS 1... Casing, 2... Hand grip, 3... Impact tool, 4... Rear part, 5... Hammer guide casing, 6... Needle bearing, 7... Internal gear, 8... External gear, 9...
...Hammer, 10...Impact cam, 11...Cam, 12...
...Impact body, 13...Tool head, 14...Camshaft, 15...
...Brim, 16...Sliding surface, 17...Ball, 18...Compression spring, 19...Friction disk, 20...Hole, 21...Push rod,
22... Longitudinal slit, 23... Pin, 24... Operation button, 26... Passage, 27... Closing valve, 28... Compression spring, 29... Piston, 30... Guide hole, 31...
Screw cap, 32... Control passage, 33... Control valve, 3
4...Vent hole, 35...Closing member, 36...Valve member, 3
7... Supply hole, 38... Discharge hole, 40... Throttle valve, 41
... Rotating sleeve, 42 ... Locking ball, 43, 44 ... Adjustment button.

Claims (1)

[Claims] 1 percussion driver with a pressure-medium-driven motor, which, when a preset predetermined starting torque is achieved, is shut off by means of a device controlled by pulses derived by the percussion movement of the hammer of the percussion driver; In the case of the type shown in FIG. It is formed by the piston 29 of the closing valve 27 for interrupting the medium flow and is provided with a return spring 28 which holds it in the open position of the pressure medium flow channel 26. The spring force of the return spring 28 is designed in such a way that it is overcome by the pressure of compressed air which is collected in the control pressure chamber by pulsating supply up to a predetermined limit value, so that the closing valve 27 is Percussion driver, characterized in that it is adapted to be moved into a closed position of the pressure medium flow path leading to the motor, and further characterized in that said control pressure chamber is connected to a ventilation device 34/35.