EP2101953A1

EP2101953A1 - Handheld tool

Info

Publication number: EP2101953A1
Application number: EP07821412A
Authority: EP
Inventors: Robert Simm; Aldo Di Nicolantonio
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2006-12-05
Filing date: 2007-10-17
Publication date: 2009-09-23
Also published as: RU2458780C2; US20100163264A1; RU2009125609A; WO2008068103A1; CN101547771B; CN101547771A; DE102006057283A1; US8083006B2

Abstract

The invention relates to a hand-held tool (1), in particular an electric handheld tool, comprising a drive motor (4), a tool shaft (14) and a first overload clutch (19) for limiting the maximum torque acting on the tool shaft (14). According to the invention, it is provided that at least a second overload clutch (20) is provided.

Description

description

title

hand tool

State of the art

The invention relates to a hand tool, in particular a

Electric hand tool, in particular a drill or a cordless screwdriver, according to the preamble of claim 1.

Hand tools with a, in particular designed as an electric motor drive motor are well known. In particular, with screwing tools, it is also known to arrange an overload clutch as a torque limiting device in the power transmission train between the drive motor and tool shaft in order to limit the maximum transferable to the tool shaft torque. When a maximum torque is exceeded, the frictional connection between the motor and the tool shaft rotationally driven tool as soon as possible interrupted to protect the operator and the machined workpiece or product.

Furthermore, hand tools with an adjustable overload clutch are known in order to adjust the maximum torque to be transmitted to the task to be done. In order to vary the torque, the spring force of a closing spring acting on a coupling part of the overload clutch, in particular a positive locking detent clutch, is varied. It has been observed that in known hand tools with adjustable overload clutch the adjuster does not always work perfectly.

DISCLOSURE OF THE INVENTION Technical Problem

The invention has for its object to provide an alternative design of a hand tool in which can be reliably selected between at least two different, maximum transferable torques.

Technical solution

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

The invention is based on the idea of providing, in addition to the first overload clutch, a second overload clutch which, alternatively and / or jointly, can be operated to transmit torque in the drive train of the hand tool. The two overload clutches are preferably non-adjustable clutches, so that an adjusting device for varying the maximum torque of each individual, separate clutch can advantageously be dispensed with. The provision of two separate overload clutches can be easily achieved by switching between the overload clutches or by closing switching the second overload clutch vary the maximum torque to be transmitted.

In an embodiment of the invention, the two overload clutches are dimensioned differently, so that in an alternative operation, two different sized torques are transferable.

In order to further increase the ease of use of the hand tool, a common switch for switching the transmission gear and for closing and / or switching off the first and / or the second overload clutch is in an embodiment of the invention in a hand tool with a shiftable transmission for switching between at least two operating speeds intended. Preferably, the common switch is coupled to at least two transmission links, wherein a first transmission linkage for switching the transmission gear and a second transmission linkage for switching the overload clutches is used.

In order to realize two different maximum transmissible torques, it is advantageously provided in a further development of the invention that the at least two overload clutches are different types of coupling. Preferably, one of the overload clutches is designed as a frictionally engaging clutch and the other overload clutch as a positive locking detent clutch (detent clutch). It is also conceivable to provide two overload clutches of identical construction, which are only dimensioned differently. It has proven to be advantageous to assign both overload clutches to a countershaft, in particular arranged parallel to the tool shaft. In this case, the overload clutches can be arranged or switched as an alternative or together for torque transmission from the drive motor to the countershaft. From the countershaft turn the torque is then transmitted, in particular with the interposition of a transmission gear, to the tool driving tool shaft or initially to one or more intermediate shafts.

According to an advantageous embodiment of the invention, it is provided that the weaker coupling (lower maximum torque) is permanently arranged so as to transmit torque, i. can not be switched on or off. Preferably, the weaker coupling is designed as a friction clutch. If required, a stronger clutch (greater maximum torque) can be connected to the weaker clutch. The stronger overload clutch is preferably designed as a form-locking latching coupling. To connect the stronger overload clutch, an axially arranged within the countershaft shift rod is provided in an embodiment of the invention. By axial displacement of the switching rod can, in particular by means of this radially adjustable balls, a positive connection between the countershaft and the stronger coupling can be made.

Alternatively, it is conceivable to provide a shift rod which can be displaced on the countershaft and which is coupled to the countershaft so as to transmit torque, in particular via a meshing engagement. The switching rod can preferably be designed as a switching sleeve, the surrounds the countershaft in sections completely. The shift rod can be adjusted between at least two shift positions in which either the first or the second overload clutch is connected to the countershaft so as to transmit torque. It is also conceivable that in a switching position both overload clutches are coupled together to transmit torque with the countershaft.

It is also conceivable to design the entire countershaft as a switching rod and to arrange axially adjustable between at least two switching positions.

According to an alternative embodiment, it is provided that the countershaft is mounted axially immovable in a hand tool housing and that the entire clutch assembly, consisting of the at least two overload clutches is relatively axially adjustable to the countershaft, wherein the coupling of the coupling components preferably takes place on the outer periphery.

Furthermore, it is conceivable for the alternative actuation of the at least two overload clutches to provide a switching wedge formed as a switching rod, which has two mutually oppositely conical sections, which cooperates with each adjustable in the radial direction balls.

Likewise, it is feasible that the stronger overload clutch is permanently arranged to transmit torque, and that a weaker overload clutch can be engaged for this, wherein in the designed state only the lower maximum torque of the weaker overload clutch is transferable. The connection and disconnection of the weaker overload Coupling can be done for example by an axially displaceably arranged on the countershaft shift rod.

Brief description of the drawings

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing; this time in:

1 shows a schematic representation of an electric hand tool,

2a shows two separate switches for switching a transmission gear and for setting two different maximum torques,

2b shows a common switch for the transmission of the transmission and two different rather maximum transmissible torques,

Fig. 3: a possible arrangement of two separate overload clutches, wherein for connection and disconnection of the stronger overload clutch slidably disposed within a countershaft

Switching rod is provided,

4 shows an alternative arrangement of two Überlastkupp ^¬ lungs, wherein a switching rod for alternative actuation of the two overload clutches is provided, wherein the shift rod is arranged axially displaceably on the outer circumference ^¬ a countershaft, 5 shows an alternative arrangement of two overload clutches, wherein the countershaft is arranged axially displaceable for the purpose of switching between the overload clutches,

6 shows an alternative arrangement of two overload clutches, wherein both overload clutches are arranged displaceably together relative to the axially fixed countershaft,

FIG. 7 shows an alternative arrangement of two overload clutches which can be operated as an alternative, wherein a wedge gear is provided for switching the overload clutches, and

Fig. 8: an alternative arrangement of two overload clutches, wherein the weaker overload clutch is switched on and off.

Embodiments of the invention

In the figures, the same components and components with the same function with the same reference numerals gekennzeich- net.

In Fig. 1, an electric hand tool 1 is shown with a housing 2. On the housing 2, a power switch 3 is arranged, with which a designed as an electric motor drive motor 4 on and off.

From a motor shaft 5, on which a driven pinion 6 rotatably seated, a torque on a drive pinion. 7 transferred, which is rotatably connected to a sleeve-shaped coupling housing 8. The clutch housing 8 belongs to two overload clutches to be explained later.

The clutch housing 8 is arranged coaxially with a countershaft 9, which is rotatably mounted within the housing 2. On the countershaft 9 sit axially adjacent two output pinion 10, 11 with different diameters. Each of the output pinions 10, 11 meshes with a drive pinion 12, 13, wherein the drive pinions 12, 13 can be coupled in a manner known per se as an alternative to transmitting torque with a tool shaft 14 passing through them, such that a torque from the drive motor 4 via the motor shaft 5 , the output pinion 6, the drive pinion 7 and the clutch housing 8 with the two overload clutches on the countershaft 9 is transferable, from where the torque on the output pinion 10, 11 and the drive pinion 12 or the drive pinion 13 to the tool shaft 14 is transferable. The tool shaft 14 in turn rotatably drives a tool 15, in this case a screwdriver bit.

In Fig. 2a, a first switch 16 and a second switch 17 (both rotary switch) are shown. The two switches 16, 17 are usually arranged on the housing 2 according to FIG. By means of the switch 16, the two drive pinions 12, 13 can alternatively be connected to the tool shaft 14 in a form-fitting manner in order to transmit torque. Switch 17 is used for switching between two maximum torque to be transmitted, ie for switching the two overload clutches. Fig. 2b shows a preferred embodiment. Here, a common rotary switch 18 is provided for switching the transmission (drive pinion 12 / drive pinion 13) and for switching between two maximum transmittable torques. The common rotary switch 18 allows the changeover between two maximum transmissible torques in both gear shift stages. For this purpose, the common switch 18 is coupled to two transmission linkages, not shown, one of which acts as an adjusting to the transmission and a further adjusting the yet to be explained overload clutches.

In Fig. 3, an arrangement of two separate overload clutches 19, 20 is shown, wherein the overload clutch 19 is formed as a friction clutch and the overload clutch 20 as a positive locking coupling, in this embodiment, the second overload clutch 20 is used to transmit a larger maximum torque. As explained with reference to FIG. 1, the clutch housing 8 is driven in rotation by a drive motor 4. The sleeve-shaped coupling housing 8 has a radially inwardly projecting ring 21, against which a coupling component 22 penetrated by the countershaft 9 is pressed on the end side in the axial direction. For axial application of force to the coupling component 22, a plate spring element 23 is provided. The coupling member 22 is positively connected via an internal toothing 24 with the countershaft 9, so that the first overload clutch 19 is arranged permanently transmitting torque. If a maximum torque is exceeded, then the static friction between coupling component 22 and ring 21 is no longer sufficient to transmit the torque to the countershaft so that the clutch housing 8 with ring 21 can rotate in the circumferential direction. moved relative to the coupling member 22, the ring 21 so guided past the coupling member 22. If a larger maximum torque to be transmitted, the second overload clutch 20 is connected. For this purpose, a switching rod 25 is provided, which is arranged displaceably in the axial direction within the countershaft 9. By moving the switching rod 25 in the plane of the drawing to the left (shown position) arranged over the circumference of the switching rod 25 switching balls 26 are pressed by means of a conical shoulder 27 outwardly in circumferentially spaced pockets 28 of a second coupling member 29 of the second overload clutch 20, whereby this form-fitting is coupled with the countershaft 9. The second coupling component 29 in turn is axially pressed by a disc spring element 30 against the ring 21 of the clutch housing 8, whereby circumferentially distributed coupling balls 31 are axially pressed into corresponding receiving pockets 32 of the ring 21, whereby a torque from the clutch housing 8, or the ring 21 is transmitted to the second coupling member 29 and from there via the switching balls 26 on the countershaft 9. If a second maximum torque is exceeded, the second coupling component 29 is moved axially by the coupling balls 31 against the force of the plate spring of the plate spring element 30, whereby the second overload coupling 20 is (temporarily) disengaged (overrunning clutch). If the second overload clutch 20 is turned off, the shift rod 25 is moved in the drawing plane to the right against the force of a coil spring 33, whereby the Schaltku- rules 26 can move radially inward, which in turn the positive connection between the second coupling member 29 and the countershaft 9 is repealed. 4, an alternative arrangement of two overload clutches 19, 20 is shown, wherein in this embodiment, the two overload clutches 19, 20 can only be operated alternatively. For this purpose, the two coupling components 22, 29 are provided on their inner circumference, each with a toothing 34, 35. By means of a non-rotatably mounted on the countershaft 9 pinion 36 is a shift rod 25 torque transmitting coupled to the countershaft 9. About an external toothing 37 formed as a sleeve switching rod 25 is connected to the toothing 34 of the first overload clutch 19 or with the toothing 35 of the second overload clutch 20 (shown) torque transmitting connectable.

In the embodiment according to FIG. 5, the countershaft 9 is adjustable relative to the two overload clutches 19, 20 in the axial direction, wherein the pinion 36 arranged rotatably on the countershaft 9 can either be engaged with the internal gearing 34 of the first overload clutch 19 (in FIG 5) or with the internal teeth 35 of the second coupling component 29 of the second overload coupling 20.

In Fig. 6, another embodiment is shown. Here, the countershaft 9 is arranged immovably. A the countershaft 9 encompassing carriage 38 is axially displaceable relative to the countershaft 9 arranged. In the circumferential direction, however, the carriage 38 is coupled with the countershaft so as to transmit torque via a web 39 (see right half of the drawing). On the carriage 38, a component 40 is provided, which serves for the rear grip of a transmission linkage, not shown. The second superimposed in this embodiment on the left The load coupling 20 has an annular coupling component 29 which is spring-loaded axially by a spring element 41 in the direction of an annular component 42, which in turn is connected in a rotationally fixed manner to the carriage 38. As a result, the coupling balls 31 engage axially in corresponding receiving pockets 32 in the annular component 42, so that a torque can be transmitted in the circumferential direction. If a maximum torque is exceeded, the coupling component 29 is moved by the coupling balls 31 in the axial direction against the spring force of the spring element 41, as a result of which the second overload coupling 20 is disengaged. The first overload clutch 19 has a coupling component 22, which is pressed by a plate spring element 23 via a further coupling component 43 in the axial direction against the annular member 42, which is non-rotatably coupled to the carriage 38 and thus torque transmitting with the countershaft 9. The two coupling components 22, 29 are each provided with an outer toothing 44, 45, which are alternatively engageable with an internal toothing 46 of the sleeve-shaped coupling housing 8 by axially displacing the carriage 38, so that either the first overload clutch 19 or the second overload clutch 20 torque transmitting can be used.

In the embodiment shown in FIG. 7, the two overload clutches 19, 20 are alternatively operated via a double wedge switching rod 25 to transmit torque, the switching rod 25 with two separate switching ball assemblies 26, 47 cooperates, via a positive connection between countershaft 9 and the two overload clutches 19, 20, can be produced. Here, the shift rod 25 is against the spring force of a coil spring 33 adjustable. It is also conceivable that the switching rod 25 can be directly coupled in both directions of operation without a coil spring. It is also conceivable that the switching rod 25 can be directly coupled in both directions of operation without a coil spring.

FIG. 8 shows an alternative exemplary embodiment, in which the second, stronger overload clutch 20 configured as a lock-up clutch is permanently arranged to transmit torque. For this purpose, an annular component 48 is permanently connected via a pinion 49 to transmit torque to the output pinion 6 of the motor shaft 5. The component 48 is seated against rotation on the outside of the clutch housing 8. Axially between the component 48 and the second coupling member 29 of the second overload clutch 20, a set of circumferentially spaced coupling ball 31 is arranged. The component 29 is spring-loaded by a disk spring element 30 in the axial direction, so that the coupling balls 31 engage axially in receiving pockets 32 of the component 48 and thus a torque in the circumferential direction can be transmitted via the positive connection produced with it. Exceeds the torque to be transmitted a maximum allowable torque, the component 29 is moved in the axial direction against the spring force of the plate spring member 30, so that the second overload clutch 20 disengages, ie engages. To the second overload clutch 20, the first overload clutch 19 can be connected. Serves for this purpose is an axially displaceable on the countershaft 9 shift rod 25 with an outer toothing 37 which is engageable with an internal toothing 34 of the first coupling member 22 of the first overload clutch 19 in engagement. The switching rod 25 is coupled in the circumferential direction torque transmitting with the countershaft 9. An annular, axially displaceable Coupling member 53 is spring-loaded by a plate spring member 23 in the direction of the first coupling member 22, whereby this between two to both sides of the coupling member 22 arranged friction jaws 50, 51 is received by clamping. In this case, the friction pad 51 is supported on a radial wall 52 of the clutch housing 8. If a maximum torque is exceeded, the friction jaws 50, 51 slide past the first coupling component 22.

Claims

claims

1. Hand tool, in particular electric hand tool (1), with a drive motor (4), with a tool shaft (14) and with a first overload clutch (19) for limiting the maximum torque acting on the tool shaft (14),

characterized,

at least one second overload clutch (20) is provided.

2. Hand tool according to claim 1, characterized in that the two overload clutch (19, 20) are designed to transmit different maximum torques.

3. Hand tool according to one of the preceding claims, characterized in that the first and the second overload clutch (19, 20) are alternatively and / or jointly arranged to transmit torque.

4. Hand tool according to one of the preceding claims, characterized in that a common switch

(17) for switching a transmission gear (12, 13) and for connecting and / or disconnecting the first and / or the second overload clutch (19, 20) is provided.

5. Hand tool according to one of the preceding claims, characterized in that the first overload clutch (19) as Reibschlusskupplung and the second overload coupling (20) is designed as a positive locking coupling.

6. Hand tool according to one of the preceding claims, characterized in that both overload clutches

(19, 20) of a, preferably parallel to the tool shaft (14) arranged, countershaft (9) are assigned.

7. A hand tool according to claim 6, characterized in that the first overload clutch (19) is arranged permanently transmitting torque, and that for switching on and / or switching off the second overload clutch (20) within the formed as a hollow shaft countershaft (9) axially displaceable switching rod (25).

8. A hand tool according to claim 6, characterized in that for connecting and / or disconnecting the first and the second overload clutch (19, 20) with the Vorgele- geweile (9) torque transmitting coupled axially outwardly along the countershaft (9) displaceable arranged switching rod (25) is provided.

9. Hand tool according to claim 6, characterized in that the countershaft (9) as axial, relative to the

Overload clutches (19, 20) displaceable switching rod (25) is formed.

10. A hand tool according to claim 6, characterized in that the two overload clutches (19, 20) are arranged together axially displaceable relative to the countershaft (9), and that both overload clutches (19, 20) in each case on its outer circumference and / or can be switched off.