WO1996030166A1

WO1996030166A1 - Motor-driven rotary percussion tool

Info

Publication number: WO1996030166A1
Application number: PCT/DE1995/000424
Authority: WO
Inventors: Georg Baersch
Original assignee: Georg Baersch
Priority date: 1995-03-29
Filing date: 1995-03-29
Publication date: 1996-10-03

Abstract

A motor-driven rotary percussion tool (1) for loosening and tightening studs or screw nuts has a housing (2) in which is arranged a motor (3) that drives a flywheel (5) by means of a driving shaft (4). The flywheel torque is transmitted by a coupling (8) to a driven shaft (9). Both the coupling (8) and driven shaft (9) are axially movable and the coupling (8) may be switched by an actuating member (13).

Description

Power driven rotary impact tool

State of the art

The invention relates to a power-driven rotary impact tool for loosening and tightening bolts, screw nuts or the like according to the preamble of the main claim.

Such power-driven rotary impact tools are already known several times and are, for example. used in assembly in manufacturing companies, in craft businesses as well as in the DIY sector. The power-driven rotary impact tools can be operated electrically or pneumatically. With the rotary hammer tools, periodic impacts are derived from the continuous starting rotary movements of the drive motor, for example in such a way that a hammer part accelerated by the motor strikes an anvil part, whereby forces or moments are achieved on the spindle that the forces or Moments on the drive motor shaft can be exceeded many times over. As a result, rotary impact tools are very powerful tools with small dimensions and small mass. In addition, no torque acts on the hand of the user in rotary impact tools, so that they guarantee safe handling.

Such rotary impact tools are, however, complex in their construction and complicated in their manufacture, so that the acquisition costs are relatively high.

Advantages of the invention e

The power-driven rotary impact tool according to the invention with the characterizing features of the main claim has the advantage over that the simple construction provides an inexpensive embodiment of a rotary impact tool which is also easy to handle. This power-driven rotary impact tool can preferably be used for loosening and tightening screw bolts or threaded nuts. The rotary impact tool, for example, makes changing a wheel in motor vehicles considerably easier and since it is relatively small, it can also be easily accommodated in smaller vehicles. The rotary impact tool has an axially displaceable output shaft which is articulated to a switchable coupling which can separate or connect the output shaft from the flywheel by means of an actuating element. The clutch engages the flywheel by means of a clutch driver and thus transmits the torque of the flywheel to the output shaft. The torque transmission is interrupted by the axial displacement of the output shaft and the output shaft comes to a standstill.

If the clutch only attacks the flywheel when it has already reached a certain speed, the torque of the flywheel is suddenly transmitted to the output shaft and the wrench attached to it. In this way, even stuck or tilted bolts can be loosened from a thread. This means that small and handy but still powerful rotary impact tools can be manufactured. Due to the principle of sudden intervention, the use of small masses and motors is sufficient, which result in a small size of the rotary impact tool.

According to an advantageous embodiment of the invention, the actuator is at least one leaf spring arranged transversely to the output shaft and clamped in the housing. The leaf spring is connected to the output shaft at the point that experiences the greatest deflection. It can be relaxed in the event that the output shaft is separated from the flywheel. If the rotary impact tool is pressed against a screw bolt, the leaf spring attached to the housing is deflected and ensures that the clutch engages the flywheel. The torque of the rotating flywheel is transferred to the wrench and the bolts can loosened or screwed tight. Slimming the

Rotary impact tool from the bolt causes the leaf spring to return to its original position, the clutch is disconnected from the flywheel, and the wrench comes to a standstill. Instead of the leaf spring, other types of springs or rubber parts can be used as actuators.

According to a further advantageous embodiment of the invention, the leaf spring is received by brackets arranged on the inside of the housing. The leaf spring is held so that it extends tangentially across the output shaft. If two leaf springs are used, they are arranged parallel to each other on the right and left of the output shaft, also tangential to it.

According to a further advantageous embodiment of the invention, a switch is arranged on the housing, on which the direction of rotation of the motor is set. Depending on which direction of rotation is selected, the rotary impact tool is used to loosen or tighten bolts. A third switch position can also be provided, in which the motor is switched off. When the rotary impact tool is pressed on, the output shaft is connected to the flywheel which is now stationary, the switched-off motor preventing the output shaft from spinning. In this way, the rotary impact tool can also be used without a motor.

According to a further advantageous embodiment of the invention, an externally operable lever is attached to the housing, which activates the actuator for separating or connecting the driving or driven parts. For example, it can be avoided that the clutch only engages when the rotary impact tool is pressed onto the screw bolt. According to a further advantageous embodiment of the invention, the coupling is disc-shaped and has at least one projection which engages in the coupling driver. The clutch driver arranged on the flywheel is advantageously of the same design as the projection on the clutch and runs on the same circular path as this. The torque can be transmitted if the coupling driver and the projection interlock.

The output shaft can be displaced in the axial direction by a stroke which corresponds at least to the height of the projection and the coupling driver. Coupling driver and projection must be so far apart in the uncoupled state that they cannot touch each other. In this way, safe handling of the rotary impact tool is guaranteed.

A plurality of projections can also be attached to the coupling and a plurality of coupling drivers can be attached to the flywheel.

According to a further advantageous embodiment of the invention, the clutch is speed-controlled and connects the flywheel to the output shaft only after it has reached a minimum speed. In this way, the torque of the flywheel can be suddenly transmitted to the output shaft and thus e.g. enable loosening of fixed bolts. In order for the angular momentum transfer from the flywheel to the output shaft to be as high as possible, the mass of the flywheel is chosen to be relatively large.

According to a further advantageous embodiment of the invention, the overload clutch arranged between the motor and the drive shaft is a torque-dependent clutch. The overload clutch thus acts as a safety clutch for the motor after a certain limit load has been exceeded separates the motor from the drive shaft. On the one hand, this is of great importance when tightening bolts, on the other hand when a torque is required to loosen the bolts that exceeds that which the motor can apply. In both cases, the overload clutch prevents the motor from being overloaded and damage to the mechanics of the rotary impact tool.

According to a further advantageous embodiment of the invention, the motor is driven by rechargeable batteries or low-voltage sources. The use of accumulators guarantees wireless and particularly flexible handling of the rotary impact tool. The tool can also be used where there is no mains connection available.

The rotary impact tool is used to change a wheel

Motor vehicles used, so it can with the help of a suitable

Cable and connector to be connected to the vehicle's cigarette lighter.

According to a further advantageous embodiment of the invention, the output shaft is axially displaced by a linkage which is actuated by a speed-dependent trigger mechanism attached to the flywheel. As soon as the flywheel reaches a minimum speed, the mechanism acts on the linkage, which moves the output shaft towards the flywheel and connects it to it. The output shaft and flywheel are thus coupled automatically and speed-controlled.

According to a further advantageous embodiment of the invention, the flywheel has a bore running in the radial direction from the outside inward, the depth of which is smaller than the radius of the flywheel and a pin in the spring is attached so that it moves radially outward when the flywheel rotates and completely immerses in the bore when the flywheel is at a standstill. This device corresponds to a speed-controlled trigger mechanism. When the disc rotates, the bolt acts on the one hand on the spring force in the direction of the center of the disc, and on the other hand the centrifugal force, which depends on the angular velocity of the disc, acts on the outside. When the disc begins to rotate, the pin moves radially outward and comes to a standstill only when the force of the spring attached and deflected to the pin is as great as the centrifugal force. As soon as the bolt protrudes from the bore in its radially outward movement, it can actuate the linkage connected to the output shaft and thereby couple the output shaft to the flywheel. If the speed is reduced again, the spring force exceeds the centrifugal force and the bolt moves radially inwards again, in the direction of the center of the disc. The connection between the pin and the linkage is interrupted and the rotary impact tool is uncoupled.

According to a further advantageous embodiment of the invention, the minimum speed of the flywheel, from which the bolt protrudes out of the bore, can be adjusted by an adjustment direction. In this way, the minimum speed of the flywheel from which the clutch connected to the output shaft engages the flywheel can be freely selected within the limits specified by the design of the trigger mechanism.

According to a further advantageous embodiment of the invention, the clutch consists of a disk, along the circumference of which a jacket is arranged, which surrounds but does not touch the flywheel and on the inside of which a radially protruding projection is attached, which is attached to the clutch driver of the Flywheel attacks. This clutch can also be used as an automatically speed-controlled clutch, in which case the speed-dependent trigger mechanism is advantageously attached to the flywheel and can engage in the projection on the inside of the jacket of the clutch.

Further advantages and advantageous embodiments of the invention can be found in the following description, the drawing and the claims.

drawing

An embodiment of the object of the invention is shown in simplified form in the drawing and is described in more detail below. Show it:

Fig.l a S chni tt by an inventive s

Rotary impact tool, Figure 2 shows a section through a rotary impact tool with a trigger mechanism arranged in a flywheel

(on an enlarged scale compared to FIG. 1), FIG. 3 shows an alternative embodiment of a clutch and a

Flywheel with a speed-dependent

Taking device.

Description of the embodiment

1 shows a section through a rotary impact tool 1 according to the invention. This has a housing, for example made of plastic, in which a motor 3 is arranged. It is preferably an electric motor. The motor 3 drives a flywheel 5 via a drive shaft 4 which is as large as possible Has mass. Between the motor 3 and the flywheel 4 there is a torque-dependent overload clutch 6, which, as soon as the torque at this point exceeds a limit value which can be set at the switch 29, separates the motor from the flywheel.

Coaxial to the common axis of rotation 7 of the flywheel 5, drive shaft 4 and motor 3, the clutch 8 and the output shaft 9 are arranged so that they can be moved axially. At the end of the output shaft 9 opposite the coupling 8, a receptacle 11 is provided, onto which different wrenches 12, such as a socket for loosening wheel nuts or bolts, can be plugged.

On the housing 2, a leaf spring 13 is fastened to brackets 14, which is connected to the output shaft 9 at the point experiencing the greatest deflection. The deflection of the leaf spring 13 takes place in the axial direction - with respect to the axis of rotation 7 - towards or away from the flywheel 5. When the spring 13 is deflected in one direction or the other, the output shaft 9 connected to the spring is moved towards or away from the flywheel 5, whereby in one case it is connected to the flywheel 5 via the coupling 8 and the disc rotates the shaft is transmitted and in the other case is separated from the flywheel 5 and comes to a standstill.

The disk-shaped clutch 8 engages via the projection 17 on the clutch driver 18, which is attached to the flywheel 5. The path covered by the output shaft 9 and the coupling 8 when the leaf spring 13 is deflected must be greater than the extension of the projection 17 and coupling driver 18 in the axial direction, so that the two parts cannot touch or influence one another in the uncoupled state. If the clutch 8 engages the flywheel 5, it will Transfer the torque of the flywheel 5 to the output shaft 9 and the wrench 12 attached to it.

The deflection 16 of the leaf spring 13 takes place by pressing the rotary impact tool 1 against a screw bolt. As a result, the clutch 8, which is moved by the spring 13 and the output shaft 9, acts on the flywheel 5, which is already rotating, driven by the motor 3. The torque of the flywheel 5 is transmitted to the wrench 12 and the screw bolt is screwed or loosened. This depends on the direction of rotation of the motor 3 set on the switch 21. When the rotary impact tool 1 is removed from the screw bolt, the leaf spring 13 automatically returns to its starting position 15 and the clutch 8 is separated from the flywheel 5.

If the wrench 12 is not to be set in rotation by pressing the rotary impact tool 1 against a screw bolt, the connection between the clutch 8 and the flywheel 5 can be established or released by actuating the lever 22.

In the embodiment of a rotary impact tool 1 shown in FIG. 1, the electric motor 3 is connected to a low-voltage source through the connection 19. There is also the option of installing 2 batteries in the housing.

The rotary impact tool 1 shown in FIG. 2 is equipped with a speed-controlled trigger mechanism 23. For this purpose, the flywheel 5 has a bore 25 running in the radial direction from the outside inwards, the depth of which is smaller than the radius of the flywheel 5. At the end of the bore 25 facing the disk axis, a bolt 24 is fastened via a helical spring. When the flywheel 5 rotates, the bolt 24 moves on account of it attacking centrifugal force, which exceeds the spring force depending on the speed of the flywheel 5, radially outwards. As soon as the bolt 24 protrudes from the bore, it can press against the linkage 27, which acts on the output shaft 9 and ensures that the clutch disc 8 is connected to the flywheel 5. On the flywheel 5, an adjusting mechanism 26 is accommodated in the additional bore running parallel to the axis of rotation 7, with the aid of which it can be set from which minimum speed of the flywheel 5 the clutch should act on it. The adjusting mechanism 26 consists of a spring-loaded locking element which presses against the bolt 24.

3 shows another embodiment of a clutch and a flywheel as an alternative to the rotary impact tools shown in FIGS. 1 and 2. The clutch 8 consists of a disk along the circumference of which a jacket 28 is arranged, which at least partially encompasses the flywheel 5, but does not touch it. On the inside of the casing 28 there is a projection 17 which projects radially in the direction of the axis of rotation 7 and which engages the coupling driver 18 of the flywheel 5. The clutch driver is equipped with a speed-controlled trigger mechanism 23. A spring-mounted bolt 24 moves radially outward when the flywheel 5 rotates and engages the projection 17. If the speed of the flywheel 5 is reduced, the bolt 24 is pulled back by the spring. In this alternative embodiment, it is not absolutely necessary that the output shaft 9 and the clutch 8 are axially displaceable.

All in the description, the following claims and the

Features shown in the drawings can be essential to the invention both individually and in any combination with one another. List of reference numbers

1 rotary impact tool

2 housings

3 engine

4 drive shaft

5 flywheel

6 overload clutch

7 axis of rotation

8 clutch

9 output shaft

10

11 recording

12 wrenches

13 leaf spring

14 bracket

15 Starting position of the leaf spring

16 deflected position of the leaf spring

17 head start

18 clutch drivers

19 connecting line

20th

21 switches

22 levers

23 Release mechanism

24 bolts

25 hole

26 adjusting device

27 rods

28 coat

29 control element

30

31

Claims

Expectations

1.Powered rotary impact tool for loosening and tightening bolts and nuts

- with a motor (3),

- With a drive shaft (4) driven by the motor (3), which in turn drives a flywheel (5), an overload clutch (6) being arranged between the drive shaft (4) and the motor (3),

- With a clutch (8) which engages on the flywheel (5) by means of a clutch driver (18),

- With a on the clutch (8) arranged output shaft (9), at the end of the clutch (8) facing away a receptacle (11) for a wrench (12) is attached and - With a housing (2) in which the driving parts, that is the motor (3), the drive shaft (4) and the flywheel (5), as well as the driven parts, that are the gripping clutch (8) and the output shaft ( 9) are housed such that the end of the output shaft (9) facing away from the coupling (8) protrudes from the housing (2), characterized in that

- That the driven parts (8, 9) are axially displaceable and

- That the clutch (8) is switchable, so that the driven parts (8, 9) of the driving parts (3, 4, 5) can be separated or connected to them by an actuator (13).

2. Power-driven rotary impact tool according to claim 1, characterized in that the actuating member is at least one transverse to the output shaft (9) arranged, in the housing (2) clamped leaf spring (13).

3. Power-driven rotary impact tool according to claim 2, characterized in that the leaf spring (13) of on the inside of the housing (2) arranged brackets (14) is received.

4. Power-driven rotary impact tool according to one of the preceding claims, characterized in that a switch (21) is arranged on the housing (2), on which the direction of rotation of the motor is set.

5. Power-driven rotary impact tool according to one of the preceding claims, characterized in that on the housing (2) an externally operable lever (22) is attached, which activates the actuator (13) for separating or connecting the driving and the driven parts.

6. Power-driven rotary impact tool according to one of the preceding claims, characterized in that the coupling (8) is disc-shaped and has at least one in the coupling driver (18) engaging projection (17).

7. Power-driven rotary impact tool according to one of the preceding claims, characterized in that the clutch (8) is speed-controlled and only after reaching a minimum speed of the flywheel (8) connects it to the output shaft (9).

8. Power-driven rotary impact tool according to one of the preceding claims, characterized in that the overload clutch (6) arranged between the motor (3) and drive shaft (4) is torque-dependent.

9. Power-driven rotary impact tool according to one of the preceding claims, characterized in that the motor (3) is driven by rechargeable batteries or a low-voltage source.

10. Power-driven rotary impact tool according to one of the preceding claims, characterized in that the output shaft (9) is axially displaced by a linkage (27) which is actuated by a speed-dependent trigger mechanism (23) attached to the flywheel (5).

1 1. Power-driven rotary impact tool according to Claim 10, characterized in that the flywheel (5) has a bore which runs in the radial direction from the outside inwards (25), the depth of which is smaller than the radius of the flywheel (5) and in which a bolt (24) is fastened by means of a spring, which moves radially outward when the flywheel (5) rotates and when the flywheel stops (5) completely immersed in the bore (25).

12. Power-driven rotary impact tool according to claim 10 or 11, characterized in that the minimum speed of the flywheel (5) from which the bolt (24) protrudes from the bore (25) is adjustable by an adjusting device (26).

13. Power-driven rotary impact tool according to one of the preceding claims, characterized in that the clutch (8) consists of a disc, along the circumference of which a jacket (28) is arranged, which at least partially encompasses but does not touch the flywheel (5), and on the inside of which there is a projection (17) which projects radially in the direction of the axis of rotation (7) and which engages on the coupling driver (18) of the flywheel (5).

14. Power-driven rotary impact tool according to claim 13, characterized in that the coupling driver (18) of the flywheel (5) is designed as a speed-dependent trigger mechanism (23).

CHANGED REQUIREMENTS

[Received at the International Office on March 12, 1996 (March 12, 1996), original claims 1-14 replaced by amended claims 1-13 4 pages)]

1.Powered rotary impact tool for loosening and tightening bolts and nuts

- with a motor (3),

- With an on the clutch (8) arranged output shaft (9), at the end of the clutch (8) facing away a receptacle (11) for a wrench (nut 12) is attached and with a housing (2) in which the driving parts, namely the motor (3), the drive shaft (4) and the flywheel (5), and the driven parts, namely the gripping coupling (8) and the output shaft (9), are housed so that the driven parts (8, 9) are axially displaceable and that the coupling (8). End of the output shaft (9) facing away protrudes from the housing (2), characterized in that

- That the clutch (8) is switchable so that by an at least one transverse to the output shaft (9) arranged in the housing (2) clamped leaf spring (13) existing actuator (13) the driven parts (8, 9) of the driving parts (3, 4, 5) can be separated or connected to them.

2. Power-driven rotary impact tool according to claim 1, characterized in that the leaf spring (13) on the inside of the housing (2) arranged brackets (14) is received.

3. Power-driven rotary impact tool according to one of the preceding claims, characterized in that a switch (21) is arranged on the housing (2), on which the direction of rotation of the motor is set.

4. Power-driven rotary impact tool according to one of the preceding claims, characterized in that on the housing (2) an externally operable lever (22) is attached, which activates the actuator (13) for separating or connecting the driving and the driven parts. 5. Power-driven rotary impact tool according to one of the preceding claims, characterized in that the coupling (8) is disc-shaped and has at least one in the coupling driver (18) engaging projection (17).

6. Power-driven rotary impact tool according to one of the preceding claims, characterized in that the clutch (8) is speed-controlled and only after reaching a minimum speed of the flywheel (8) connects it to the output shaft (9).

7. Power-driven rotary impact tool according to one of the preceding claims, characterized in that the overload clutch (6) arranged between the motor (3) and drive shaft (4) is torque-dependent.

8. Power-driven rotary impact tool according to one of the preceding claims, characterized in that the motor (3) is driven by rechargeable batteries or a low-voltage source.

9. Power-driven rotary impact tool according to one of the preceding claims, characterized in that the output shaft (9) is axially displaced by a linkage (27) which is actuated by a speed-dependent trigger mechanism (23) attached to the flywheel (5).

10. Power-driven rotary impact tool according to claim 9, characterized in that the flywheel (5) has a radial direction from the outside inward bore (25), the depth of which is smaller than the radius of the

βöHB »« * ^* - ** 2ö

Flywheel (5) and in which a bolt (24) is fastened via a spring, which moves radially outwards when the flywheel (5) rotates and, when the flywheel (5) is at a standstill, completely immerses in the bore (25).

1 1. Power-driven rotary impact tool according to claim 9 or 10, characterized in that the minimum speed of the flywheel (5) from which the bolt (24) protrudes out of the bore (25) is adjustable by means of an adjusting device (26).

12. Power-driven rotary impact tool according to one of the preceding claims, characterized in that the coupling (8) consists of a disc, along the circumference of which a jacket (28) is arranged, which at least partially encompasses but does not touch the flywheel (5), and on on the inside of which there is a projection (17) which projects radially in the direction of the axis of rotation (7) and which engages on the coupling driver (18) of the flywheel (5).

13. A power-driven rotary impact tool according to claim 12, characterized in that the coupling driver (18) of the flywheel (5) is designed as a speed-dependent trigger mechanism (23).

rtUrmm * - «*« - *