GB2232625A

GB2232625A - Angle screwdriver

Info

Publication number: GB2232625A
Application number: GB9011207A
Authority: GB
Inventors: Reinhold Stroezel
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1989-06-16
Filing date: 1990-05-18
Publication date: 1990-12-19
Anticipated expiration: 2010-05-18
Also published as: SE509657C2; DE3919648A1; GB9011207D0; JPH0326470A; SE9002131D0; DE3919648C2; GB2232625B; SE9002131L

Description

A - 1 Anale-Screwdriver Prior Art is

The invention starts f rom an angle screwdriver according to the generic category of Claim 1.

German Offenlegungsschrift 3,409,395 discloses a congeneric angle screwdriver. In this publication it is proposed to provide an angle screwdriver having an angle head with a clutch system known per se in straight screwdrivers. This clutch system contains a disconnecting clutch having a torque limiter for Interrupting the force transmission from the screwdriver motor to the axially displaceable screwdriver spindle. Engagement is here effected by an axial movement of the screwdriver spindle when placing on to a part to be screwed right at the start of each screwdriving operation.

This known clutch system has an excessive overall length for fitting in the angle head. It can therefore only be fitted in the motor housing and gearbox arranged at right angles thereto. In this fitted position, unlike straight screwdrivers, additional actuating means are necessary for the disconnecting clutch so that the latter functions and so that an axial displacement becomes effective at the disconnecting clutch. On the other hand. in the angle screwdriver this axial displacement would have to be passed "around the corner" so to speak so that the clutch system can be adopted without greater changes. However. the appropriate means for diverting this axial displacement would involve significant development costs.

In order to avoid this expense, the known angle screwdriver was designed in such a way that the disconnecting clutch could be tightened manually after every screwdriving operation. The tightening means is a Bowden wire or a lever with a shift linkage. This arrangement is expensive, complicated and susceptible to trouble. The amount of effort involved is greater compared with straight screwdrivers.

is Advantages of the invention The.angle screwdriver according to the invention, having the characterizing features of Claim 1,, makes possible the automation of the proven clutch system known _in straight screwdrivers and consisting of a disconnecting clutch having a longitudinally moveable screwdriver spindle and a torque limiter for interrupting the force transmission from the screwdriver motor to the screwdriver spindle. The particular advantage compared with straight screwdrivers is that any number of screwdriving operations are possible in succession without any expenditure of force beyond holding and guiding the angle screwdriver. A separate handle for engaging the disconnecting clutch with the corresponding transmission means is superfluous.

Further. advantageous developments of the invention follow from the subclaims.

Drawing An exemplary embodiment of the invention is described below together with the associated drawing. Fig. 1 shows a partial longitudinal section of the angle screwdriver and Fig. 2 shows a longitudinal section of the gearing with adjacent parts.

Description of the exemplary embodiment

In Figure 1. a motor housing 1, a gearbox 2, an angle-head housing 3 and a handle housing 4 form an entire housing for an angle screwdriver. The motor housing 1 accommodates an electric motor - the screwdriver motor 5.Its motor shaft 6 can be coupled to the screwdriver spindle 20 via the parts arranged in the gearbox 2. The angle-head-side end of the screwdriver spindle 20 forms a bevel gear 53 which is mounted in rolling bearings 54 in the angle-head housing 3. The bevel gear 53 is in mesh with a companion bevel gear 59. The latter is mounted in rolling bearings 60. 62 in the angle-head housing 3 and carries a hexagon piece 63 with a catch locking feature 71 for accommodating a screwdriver blade (not shown) or a hexagon box spanner. A trigger 55 for a switch 56 for switching the screwdriver 1 is motor 5 on and of f is arranged in the handle housing 4 and is rotatably mounted via a pivot 57. A connecting cable 58 runs via the switch 56 to the screwdriver motor 5.

In Figure 2. the motor shaft 6 is mounted in a roller bearing 7 in the gearbox 2 and Is designed at the end as a pinion 8. The pinion 8 meshes with planet gears 9 carried centrally by a clutch part 10. These planet gears 9 are supported on a fixed companion tooth system 11 on the gearbox 2. The clutch part 10 is seated in a rotatable and displaceable manner on a control shaft 12 which is arranged parallel to the motor shaft 6. A helical spring 13 seated between the clutch part 10 and the pinion 8 on the control shaft 12 acts upon the clutch part 10 always towards the angle-head housing 3.

A bearing 14 for a driving sleeve 15 is seated in the gearbox 2. This driving sleeve 15 carries radially outer planet gears 16 which on one side mesh with a f ixed companion tooth system 17 of the gearbox 2 and on the opposite side with a pinion 18. The pinion 18 is the angle-head-side end of a cylindrical thrust piece 19 and, just like the planet gears 16 and the companion tooth system 17. has a helical tooth system. The latter has a helix angle which definitely excludes self-locking. on the angle- head side,, the driving sleeve 15 centrally accommodates a screwdriver spindle 20 in a longitudinally displaceable and rotationally locked manner. The screwdriver spindle 20 is in alignment with the thrust piece 19.

The handle-side end of the thrust piece 19 is centrally accommodated in a bore 21 of a collar sleeve 22 in a longitudinally displaceable and rotationally locked manner. Likewise, the angle-head-side end of the control shaft 12 - from the handle side - engages into the bore 21 and is rotatably mounted in the latter. Arranged in the bore 21 between the control shaft 12 and the thrust piece 19 is a ball 23 which,, on the angle-head side, touches the thrust piece 19. A helical spring 24 is supported on the ball 23 and is guided in a central is stepped bore 25 of the control shaft 12. At the end of the stepped.bore 25, the spring 24 is supported against a further ball 26. Allocated to the ball 26 is a stop pin 27 at the inner end of the stepped bore 25. A radial bore 28 leads from the end of the stepped bore 25 through the side wall of the control shaft 12 and accommodates a smaller ball 29. The ball 26 acts upon and holds the smaller ball 29, supported on it, radially outwards under the action of the helical spring 24. When the angle screwdriver is being assembled,, the stop pin 27 prevents the smaller ball 29 from falling into the bore 25 during mounting.

The angle-head-side end face of the clutch part 10 has a recess 30. Clutch teeth 31 project from its end face. Allocated to these clutch teeth 31 are companion teeth 32 which is seated on a clutch sleeve 33. The clutch sleeve 33 overlaps a collar of a threaded sleeve 34 and is screwed to the latter by a thread 35. The clutch sleeve 33 also overlaps the hand-side end of the collar sleeve 22, which forms a collar 36 at this location. At the end face, the collar 36 has teeth 37 with the function of a torque limiter. A base 39, configured in a pot shape,, of the clutch sleeve 33 has radial location bores for cylinder rollers 40. The end faces of the teeth 37 bear against these cylinder rollers 40 with the collar sleeve 22 being acted upon by a helical spring 41. The latter finds its abutment on a supporting ring 42 which bears against the threaded sleeve 34. The supporting ring 42, bevelled on the outside, presses a ball 44 into a longitudinal groove 45 in the clutch sleeve 33. A locking pin 47 is guided in a radial bore 46 in the wall of the gearbox 2. The angle-head-side end of the clutch sleeve 33 near to the radial bore 46 has teeth 48 which are allocated to the teeth (not shown) of a special adjusting key similar to a drill chuck key.

The gearbox 2 and the angle-head housing 3 are connected by means of a threaded sleeve 49 and a snap ring 50. With means not described in detail, the anglehead housing 3 can be locked in various rotational 1 lk-- is positions about the longitudinal axis of the gearbox 2 of the angle screwdriver.

To screw in. for example, a hexagon-head screw, the angle screwdriver, with the appropriate hexagon box spanner or a f lat-tipped screwdriver bit together with the screw held by the latter. is put on to the screw hole or on to the hexagon-head screw already located or initially screwed with a few turns. The screwdriver motor 5 is switched on and the clutch part 10 driven by pressing the trigger 55. The thrust piece 19 together with the ball 23 Is displaced to the right (in the direction of view) by the helical tooth system of the pinion 18 or of the planet gears 16. As a result. the spring 24. the ball 26 and the small ball 29 are acted upon, tightened and thus made ready for operation. At the same time,, the drive movement of the screwdriver motor 5 is transmitted via the clutch sleeve 33 to the screwdriver spindle 20. The latter# via the companion gears 53f 59, drives the hexagon piece 63 and thus the screw to be screwed.

If the set limit torque is reached upon tightening the screw, the cylinder rollers 40 run on to the backs of the teeth 37. The disconnecting clutch, consisting of the clutch sleeve 33 and the clutch part 10,7 is thereby thrust towards the motor housing 1. Just before the crown of the teeth 37 is reached, the clutch part 10 comes into a position In which the smaller ball 29 is thrust by the ball 26 into the recess 30 in the clutch part 10. As soon as the crown-of the teeth 37 Is crossed, the clutch sleeve 33# with its cylinder rollers 40, as a result of the force of the spring 41. falls back abruptly into the gaps between the teeth 37. The clutch part 10 is held back by the small ball 29. As a result. the clutch teeth 311 32 are disengaged and thus the drive on the screw is interrupted. If the trigger 55 is released. the screwdriver motor 5 is switched off. By torque no longer acting on the screwdriver spindle 20 or on the thrust piece 19,, the latter returns into its initial position as a result of axial displacement by the helical spring 24. In the process. the helical spring 24 relaxes to the extent that its force is no longer sufficient to hold the smaller ball 29 in its blocking position against the action of the helical spring 13 acting on the clutch part 10. The clutch part 10, returning into its engagement position, presses the smaller ball 29 back into its radial bore 28 in the control shaft 12. The screwdriver is now ready to start. A new screw-in cycle can begin.

If the transferable limit torque is to be changed. the threaded sleeve 34, by means of a special key (not shown), is axially displaced via the teeth 48 relative to the clutch sleeve 33 in such a way that the initial tightening of the helical spring 41 changes in the desired manner. The higher the initial tightening, the greater is the limit torque. Unintentional change of the limit torque is prevented by the pressure of the supporting ring 42 on the ball 44 in the longitudinal groove 45.

Use of the invention in straight screwdrivers would free these straight screwdrivers from a hitherto functionally necessary, axial action of force to be applied by the operator. This could make the work easier, for example in difficult assembly positions. For certain standardscrewdriving cases, the use of a disconnecting clutch according to the invention is of particular advantage in automatic screwdriving stations.

If the angle head is designed to be pivotable, the angle screwdriver according to the invention can also be used as a straight screwdriver.

1 4 4

Claims

1. Angle screwdriver comprising a multipiece screwdriver spindle (20) and a disconnecting clutch (10. 191 22,, 33) which can be engaged and disengaged by longitudinal displacement and is designed as a torque limiter for Interrupting the force transmission from the screwdriver motor (5) to the screwdriver spindle (20),, characterized in that the disconnecting clutch (10. 19, 22, 33) is engaged as soon as the screwdriver motor (5) stops, and in that, when the screwdriver spindle (20), previously not moving. rotates. at least one spring (24) or the like Is tightened which acts upon locking means (26. 29) which - in a manner known per se, as long as they are acted upon - keep the disconnecting clutch (10. 19r 22, 33) disengaged after a limit torque is exceeded.

2. Angle screwdriver according to Claim 1. characterized in that a pinion (18) having a helical tooth system or coarse threads or the like on the screwdriver spindle (20) itself or on a part coupled to the latter in its axial extension interacts with a thrust piece (19), rotatable relative to the screwdriver spindle (20) or to the coupled part and having a suitable companion tooth system or the like. in such a way that. when the screwdriver spindle (20) rotates in the screw-in direction, this thrust piece (19) performs an axial displacement tightening the spring (24).

3. Angle screwdriver according to Claim 2. characterized in that the angle screwdriver can be used as a straight screwdriver by adjusting the angle-head housing (3).

4. An angle screwdriver substantially as herein described with reference to the accompanying drawings.

Published 1990 at The Patent Office, Ststp. House. 6671 HighHolborn. London WClR4TP. Further copies maybe obtainedfrom The Patent Office. Sales Branch, St Mary Cray, Orpington, Rent BR5 3P.D. Printed by Multiplex techniques ltd, St Mary Cray, Kent, Con. 1/87