DE8904356U1 - Electric motor driven hand screwdriver - Google Patents

Description

•··· ta ·

License

Patent-Verwaltungs-GmbH Theodor-Stern-Kai 1, 6000 Frankfurt 2

Electric motor driven hand screwdriver

The invention relates to a hand screwdriver according to the preamble of claim 1.

Such handheld screwdrivers, often powered by batteries, have a certain urgency in that the reaction torques that occur at high tightening torques and especially in hard screwing applications are considerable.

The invention is based on the object of creating hand screwdrivers of the generic type with which high tightening torques and hard screwing can be achieved without particularly noticeable reaction torques.

This object is achieved according to the invention by the characterizing features of claim 1.

Further developments and expedient embodiments of the invention are specified in the subclaims.

The invention is explained below with reference to the drawing, which schematically illustrates a cordless hand screwdriver.

Shown are: Fig. 1 a longitudinal section through the gear part of a Cordless screwdrivers,

Fig. 2 is a view along the section α-λ through Figure 1.

As can be seen from Figure 1, the armature pinion 10 of a battery-powered motor 11 or a motor connected to mains voltage drives a gear 13 provided with an internal toothing 12, which is rotatably arranged on a shaft journal 15 mounted in the bearing plate 14.

The gear 13 is designed here as a ring gear with a hub 16. The hub 16 serves as a seat for a ball bearing 17 and has an internal hexagon 18 into which the drive shaft 19 of a hydraulic viscous drive 20, also designed as a hexagon, engages. Such viscous drives are known and are used in pneumatic screwdrivers. They convert the torque acting on their drive shaft 19 into pulse-shaped shocks. The pulsating mode of operation enables the screwing process to be accelerated in addition to a high tightening torque with a barely perceptible reaction torque. Furthermore, the damping fluid in the viscous drive reduces noise.

The viscous drive 20 is housed in a housing 21, to which a support and holding part 22 is assigned, which can be formed in one piece with the gear housing 23 or can be a separate component which is fixedly or detachably connected to the gear housing 23. On the inner circumference of a collar-shaped extension 24 of the support and holding part 22, obtained by reducing the inner diameter of the gear housing 23, a thread is attached, into which the thread cut 26 of the housing 21 is screwed.

The housing 21 for the viscous drive 20 could also be connected to the gearbox housing 23 by means of a bayonet lock or similar device.

The outer ring of the ball bearing 17 rests on the drive-side surface of the projection 24. To secure this ball bearing

-· 3

bearing against axial displacement, a spring ring 2 7.

The coupling of the machining tool 7.B. in the form of a screw blade with the working shaft 28 of the viscous drive can be done directly by inserting the tool in question into a hexagon socket of the working shaft with locking of the machining tool in the inserted position or indirectly with the help of a

A π d p t &thetas; r S e r f &udiagr; 1 y e Γ&igr;.

The operation of the hand-held screwdriver described is as follows:

The pinion 10 mounted on the shaft 30 of the drive motor 11 arranged in the screw drive 31 replaces the ring gear in rotation. The drive shaft 19 of the viscous drive mechanism 20 is driven by the gear 13 by means of the hexagon socket 16 of the gear 13. The torque acting on the drive shaft 19 is thereby converted into pulse-shaped shocks. These shocks are transmitted to the relevant machining tool via the working shaft 28.

If necessary, additional gear stages can be provided between the gear 13 and the drive pinion 10. The shaft journal 15 can also be galvanized if necessary, since the gear 13 is normally sufficiently guided and centered by the inner ring of the ball bearing 17.

Claims (7)

j j U.Cen:t is; . ·[[ ;"; P a tent -;Verw*a 1X u Ag s -;Gfffbf-I.'; Theodor-Stern-Kai 1, 6000 Frankfurt 2 WN 89/08 Claims 1. Electric motor driven hand screwdriver with a single or multi-stage gear, characterized in that the gear housing (23) is provided with a support and holder (22) for the housing (21) of a hydraulic viscous drive (20), the drive shaft (19) of which is coupled to the gear wheel (13) of the drive shaft of the hydraulic drive. 2. Hand screwdriver according to claim 1, characterized in that the gear (13) is rotatably mounted in the support and holding part (22) of the gear housing (23) and is provided with a hexagon socket (18) for receiving the drive shaft (19) of the viscous drive mechanism (20). 3. Hand screwdriver according to claims 1 and 2, characterized in that the gear (13) is designed as a hub (16) provided with a hollow wheel, which serves as a - i t ζ for a ball bearing (17) arranged in the gear housing (23) and has the hexagon socket (18). 4. Hari' screwdriver according to claims 1 to 3, characterized in that the supporting and holding part (22) of the gear housing (23) has a collar-shaped projection (24) obtained by a diameter reduction, which serves as a bearing surface for the ball bearing (17). 5. Hand screwdriver according to claims 1 to 4, characterized in that a thread (25) is provided in the gear housing (23), into which the housing (21) of the viscous drive (20), provided with a corresponding external thread (26), is screwed. 6. Hand screwdriver according to claims 1 to 5, characterized in that the support and holding part (22) for the housing (21) of the viscous drive (20) is designed as a separate component that is firmly connected to the gear housing (23). 7. Hand screwdriver according to claims 1 to 6, characterized in that a battery serves as the voltage source