WO2012119312A1

WO2012119312A1 - Safety clutch

Info

Publication number: WO2012119312A1
Application number: PCT/CN2011/071658
Authority: WO
Inventors: Yi Li; Tie CHEN
Original assignee: Bosch Power Tools (China) Co., Ltd.
Priority date: 2011-03-10
Filing date: 2011-03-10
Publication date: 2012-09-13

Abstract

A safety clutch device for a hand-held power tool, comprising: a transmission shaft (10a); a pinion (12a) which is provided to be driven by the transmission shaft (10a); a gearwheel (14a; 14b) which is provided to be driven by the pinion (12a); a driven shaft (16a; 16b) which is provided to be driven by the gearwheel (14a; 14b); and a flexible tolerance ring (18a; 18b) which is provided to transmit a force from the transmission shaft (10a) to the driven shaft (16a; 16b).

Description

Safety clutch

Technical Field

The invention relates to an improved safety clutch for a hand-held power tool. Prior Art

Safety clutches for hand-held power tools, in particular for hammer drills, comprising a transmission shaft, a pinion which is provided to be driven by the transmission shaft, a gearwheel which is provided to be driven by the pinion, a driven shaft which is provided to be driven by the gearwheel and a tolerance ring, are already known. Such safety clutches comprise a catch disk which is provided to drive the gearwheel.

Summary of the Invention

The invention relates to a safety clutch for a hand-held power tool, comprising a transmission shaft, a pinion which is provided to be driven by the transmission shaft, a gearwheel which is provided to be driven by the pinion, a driven shaft which is provided to be driven by the gearwheel and a flexible tolerance ring which is provided to transmit a force from the transmission shaft to the driven shaft. In this context, the term "tolerance ring" shall particularly define a ring, which is arranged between two parts and which can compensate for tolerances. Thereby, a compact structure of the safety clutch can be achieved at low costs and/or with few parts.

At least a portion of the tolerance ring according to the invention comprises a wave- shaped design. In this way, the tolerance ring can advantageously be formed flexible and/or spring-elastic. In this context, the term "wave-shaped" shall particularly define a wave-like or undulated shape of an element. A further spring-elastic element can therefore be avoided and the number of parts of the safety clutch and/or production costs can advantageously be reduced. In this context, the hand-held power tool can be configured as a hammer drill with a hammer pipe.

In another embodiment of the invention, the tolerance ring is mounted in a rotatably fixed manner on at least one of the shafts. Thus, the tolerance ring can be mounted in a space-saving and durable way.

If the pinion is directly coupled to the tolerance ring via a non-positive connection and provided to slip over the tolerance ring in the case of a defined torque of the transmission shaft being exceeded, the safety clutch can interrupt a flow of force in an advantageously simple way. Furthermore, the pinion and the tolerance ring comprise a plurality of contact areas and the contact areas are separated from each other. In this context, the term "contact area" shall define a continuous area, wherein at least two separated parts are in contact with each other and/or wherein a force between at least two separated parts may occur. Thereby, a flexibility of the tolerance ring can be increased and/or a thermal loading can be reduced when a flow of force is interrupted.

If, seen in a radial direction from the transmission shaft, the tolerance ring is located in front of the pinion, the tolerance ring can advantageously be integrated into the transmission in a compact manner.

In another embodiment of the invention, the gearwheel is directly coupled to the tolerance ring via a non-positive connection and provided to slip over the tolerance ring in the case of a defined torque of the gearwheel being exceeded. Thereby, the safety clutch can interrupt a flow of force in an advantageously simple way.

Furthermore, the gearwheel and the tolerance ring comprise a plurality of contact areas and the contact areas are separated from each other. Thereby, a flexibility of the tolerance ring can be increased and/or a thermal loading can be reduced when a flow of force is interrupted.

In another embodiment of the invention, seen in a radial direction from the driven shaft, the tolerance ring is located in front of the gearwheel. Thereby, the tolerance ring can advantageously be integrated into the transmission in a compact manner.

Brief Description of the Drawings

Other objects, features and advantages of the present invention will become apparent from a reading of the following detailed description when taken in conjunction with the accompanying drawings wherein a particular embodiment of the invention is disclosed as an illustrative example.

Fig. 1 shows a view of a safety clutch for a hand-held power tool,

Fig. 2 shows a detail view of a tolerance ring of the safety clutch of Fig. 1,

Fig. 3 shows a view of the tolerance ring mounted on the transmission shaft, and

Fig. 4 shows a view of the tolerance ring mounted on the driven shaft.

Detailed Description of the Invention

Figure 1 shows a safety clutch device for a hand-held power tool, comprising a transmission shaft 10a and a pinion 12a which is provided to be driven by the transmission shaft 10a. The transmission shaft 10a is driven by an electric motor 22a through a gear mechanism 24a. A person skilled in the art would also consider to directly drive the transmission shaft 10a by a motor.

At one end 26a of the transmission shaft 10a, which faces the electric motor 22a, a wobble bearing 28a is mounted on the transmission shaft 10a. The wobble bearing 28a transforms a rotational movement of the transmission shaft 10a into an axial movement of a hammer part 30a which is inserted into a driven shaft 16a.

The driven shaft 16a is driven by a gearwheel 14a which is driven by the pinion 12a. The gearwheel 14a is mounted on the driven shaft 16a in a rotatably fixed manner. At one end 32a of the driven shaft 16a, which is on an opposite side of the gearwheel 14a, a tool holder 34a is mounted to accommodate a tool (not shown).

A tolerance ring 18a is shown in a detail view in Figure 2. The tolerance ring 18a comprises a wave-shaped design 20a that results from a flat wall ring 36a which is bent by twelve evenly distributed waves 38a. The waves 38a of the tolerance ring 18a comprise contact areas 42a at each top of an outside 40a of the tolerance ring 18a. The contact areas 42a are separated from each other and provided to absorb forces to or from the tolerance ring 18a in an assembled state.

The tolerance ring 18a is made of plastic material. In another embodiment of the invention the tolerance ring 18a is made of steel. A person skilled in the art would also consider further materials for the tolerance ring 18a, such as compound materials, iron, rubber, etc.

Figure 3 shows a view of the safety clutch device with the tolerance ring 18a in an assembled state. The tolerance ring 18a is pressed on the transmission shaft 10a and mounted in a rotatably fixed manner by a welding process. A person skilled in the art would consider several possibilities of mounting the tolerance ring 18a in a rotatably fixed manner on the transmission shaft 10a, such as gluing, soldering or positive locking.

The pinion 12a is pressed on the tolerance ring 18a which then transmits all forces from the transmission shaft 10a to the driven shaft 16a. The pinion 12a is directly coupled to the tolerance ring 18a via a non-positive connection and slips over the tolerance ring 18a in the case of a defined torque of the transmission shaft 10a being exceeded. In this case, the flow of force from the transmission shaft 10a to the driven shaft 16a is interrupted.

The contact areas 42a of the tolerance ring 18a are in contact with the pinion 12a. Seen in a radial direction 44a from the transmission shaft 10a, the tolerance ring 18a is located in front of the pinion 12a. In other words, the tolerance ring 18a is arranged between the transmission shaft 10a and the tolerance ring 18a.

Another embodiment of the invention is shown in Figure 4. The following descriptions have been mainly confined to highlight the differences between the two embodiments. To distinguish the embodiments, the letter a in the reference numerals of the embodiment in Figures 1 to 3 is replaced by the letter b in the reference numerals of the embodiments of Figure 4. Unmodified components, particularly components with the same reference numerals, can be referred back to the drawings and/or description of the first embodiment.

Figure 4 shows a view of a driven shaft 16b of a safety clutch device and a tolerance ring 18b in an assembled state. The tolerance ring 18b is pressed on the driven shaft 16b and mounted in a rotatably fixed manner by a welding process. A person skilled in the art would consider several possibilities of mounting the tolerance ring 18b in a rotatably fixed manner on the driven shaft 16b, such as gluing, soldering or positive locking.

A gearwheel 14b is pressed on the tolerance ring 18b which then transmits all forces from a pinion (not shown) to the driven shaft 16b. The gearwheel 14b is directly coupled to the tolerance ring 18b via a non-positive connection and slips over the tolerance ring 18b in the case of a defined torque of the driven shaft 16b being exceeded. In this case, the flow of force from the gearwheel 14b to the driven shaft 16b is interrupted.

Contact areas 42b of the tolerance ring 18b are in contact with the gearwheel 14b. Seen in a radial direction 44b from the driven shaft 16b, the tolerance ring 18b is located in front of the gearwheel 14b. In other words, the tolerance ring 18b is arranged between the driven shaft 16b and the tolerance ring 18b.

The gearwheel 14b and the tolerance ring 18b comprise a plurality of contact areas 42b and the contact areas 42b are separated from each other.

Claims

1. A safety clutch device for a hand-held power tool, comprising:

a transmission shaft (10a); a pinion (12a) which is provided to be driven by the transmission shaft (10a);

a gearwheel (14a; 14b) which is provided to be driven by the pinion (12a); a driven shaft (16a; 16b) which is provided to be driven by the gearwheel (14a; 14b); and

a flexible tolerance ring (18a; 18b) which is provided to transmit a force from the transmission shaft (10a) to the driven shaft (16a; 16b).

2. The safety clutch according to claim 1, wherein at least a portion of the tolerance ring (18a; 18b) comprises a wave-shaped design (20a).

3. The safety clutch according to claim 1 or 2, wherein the tolerance ring (18a; 18b) is mounted in a rotatably fixed manner on at least one of the shafts (10a; 16b).

4. The safety clutch according to one of the preceding claims, wherein the pinion (12a) is directly coupled to the tolerance ring (18a) via a non-positive connection and provided to slip over the tolerance ring (18a) in the case of a defined torque of the transmission shaft (10a) being exceeded.

5. The safety clutch according to claim 4, wherein the pinion (12a) and the tolerance ring (18a) comprise a plurality of contact areas (42a) and the contact areas (42a) are separated from each other.

6. The safety clutch according to at least claim 4, wherein, seen in a radial direction (44a) from the transmission shaft (10a), the tolerance ring (18a) is located in front of the pinion (12a).

7. The safety clutch according to one of the preceding claims, wherein the gearwheel (14b) is directly coupled to the tolerance ring (18b) via a non-positive connection and provided to slip over the tolerance ring (18b) in the case of a defined torque of the gearwheel (14b) being exceeded.

8. The safety clutch according to claim 7, wherein the gearwheel (14b) is directly coupled to the tolerance ring (18b) via a non-positive connection and provided to slip over the tolerance ring (18b) in the case of a defined torque of the gearwheel (14b) being exceeded.

9. The safety clutch according to claim 7, wherein the gearwheel (14b) and the tolerance ring (18b) comprise a plurality of contact areas (42b) and the contact areas (42b) are separated from each other.

10. The safety clutch according to claim 7, wherein, seen in a radial direction (44b) from the driven shaft (16b), the tolerance ring (18b) is located in front of the gearwheel (14b).

11. A tolerance ring (18a; 18b) comprising a wave-shaped design (20a) of the safety clutch according to claim 1.