EP2601017A1

EP2601017A1 - Striking mechanism

Info

Publication number: EP2601017A1
Application number: EP10852682.3A
Authority: EP
Inventors: Tie CHEN; Haihua Chai; Yi Li
Original assignee: Bosch Power Tools China Co Ltd
Current assignee: Bosch Power Tools China Co Ltd
Priority date: 2010-06-09
Filing date: 2010-06-09
Publication date: 2013-06-12
Also published as: RU2012158211A; CN102933352A; WO2011153689A1

Abstract

A striking mechanism for a hand-held power tool, comprising: a hammer (12) and a piston (14) to produce a striking pulse; a shaft (16) to drive said piston (14); and at least one connecting rod (18) to connect said shaft (16) to said piston (14); wherein said shaft (16) comprises a transmission portion (20) which is provided to convert a rotary motion of said shaft (16) into a reciprocating motion of said piston (14).

Description

Striking Mechanism

Prior Art Striking mechanisms for hand-held power tools, in particular for drill hammers and/or chipping hammers, which comprise a hammer and a piston to produce a striking pulse, are well-known. Such striking mechanisms comprise a structure to convert a rotary motion of a shaft into a reciprocating motion of the piston to produce a striking pulse.

Summary of the Invention

The invention relates to a striking mechanism for a hand-held power tool, in particular a drill hammer and/or a chipping hammer. The striking mechanism of the present invention comprises a hammer and a piston to produce a striking pulse, a shaft to drive the piston and at least one connecting rod to connect the shaft to the piston.

The shaft according to the invention comprises a transmission portion which is provided to convert a rotary motion of the shaft into a reciprocating motion of the piston. In this context, the term "hammer" shall define a part which is provided to produce a pulse in cooperation with the piston, in particular an axial striking pulse, and/or to directly or indirectly transmit a pulse, in particular an axial striking pulse, to a tool of the hand-held power tool which is inserted into a tool holder of the hand-held power tool. The tool can be configured as a drill or a chisel. To indirectly transmit the striking pulse to the tool, the striking mechanism further comprises a striker that is formed by a part which is separate from the hammer. The striker directly contacts the tool to transmit the striking pulse when the striking mechanism is operated. The piston according to the invention is preferably configured as a pot-shaped piston. It is also possible to configure the piston in another shape which is considered expedient by a person skilled in the art.

Furthermore, in this context the term "transmission portion" shall define a portion, in particular a portion of the shaft of the striking mechanism, which has a geometrical shape by which a rotary motion of the shaft can be converted into a reciprocating motion of the piston. The transformation of the rotary motion into the reciprocating motion is essentially generated by the cooperation of the shaft and the at least one connecting rod. The reciprocating motion of the piston is essentially transmitted from the shaft to the piston via the at least one connecting rod. It is also possible to provide more than one connecting rod to transmit the reciprocating motion of the piston from the shaft. A person skilled in the art is undoubtedly able to select a suitable number of connecting rods that meets the requirements from the specific use of the striking mechanism. The reciprocating motion of the piston proceeds along an axis which is substantially parallel to a rotation axis of the shaft. In a preferred embodiment of the present invention the transmission portion is formed in one piece with the shaft. Thereby, an advantageously simple and compact structure of the striking mechanism according to the invention can be achieved.

In addition, the transmission portion of the shaft comprises at least one angled portion that is angled in relation to an axial direction of said shaft. The term "angled portion" shall define a portion of the transmission portion, in particular the angled portion of the transmis- sion portion, which deviates from the axial direction of the shaft. The angular deviation of the transmission portion relative to the shaft, in particular from the axial direction of the shaft, advantageously ranges between 10° to 30°. In a preferred embodiment of the invention the angular deviation ranges between 15° to 20°. The angled portion of the transmission portion can be configured as a sharp-edged angled portion or as a curved angled portion. In this con- text the term "axial direction of the shaft" shall define a direction that is essentially coaxial to the rotation axis of the shaft. Thereby, a constructively simple transformation of a rotary motion into a reciprocating motion can be achieved.

In a preferred embodiment of the striking mechanism of the present invention the transmission portion of the shaft is essentially V-shaped. In this context, the term "V-shaped" shall define a geometrical shape of the transmission portion, which is in at least one position of the transmission portion and/or the shaft essentially shaped like the letter "V". It is also possible to configure the transmission portion in another shape, e.g. W-shaped or the like, which is considered expedient by a person skilled in the art. In this connection, the transmission portion of the shaft comprises a first leg and a second leg which are angled to each other and to said axial direction of said shaft. The term "angled" shall define a deviation, in particular an angular deviation, from an axial direction of the first leg in relation to an axial direction of the second leg and/or a deviation, in particular an angular deviation, from the axial direction of the shaft in relation to the axial direction of the first leg and the axial direction of the second leg of the transmission portion. It is also possible to provide the transmission portion only with the first leg so that one side of the transmission portion is located in a plane in which the axial direction of the shaft extends and an opposite side of the transmission portion is located in a plane which is displaced parallel to the plane in which the axial direction of the shaft extends. Thereby, a displacement of the transmission portion and/or the shaft along a direction perpendicular to the rotation axis and/or the axial direction of the shaft can be achieved.

Moreover, the first leg and the second leg of the transmission portion of the shaft enclose an obtuse angle. Such a construction of the transmission portion makes it possible to return to a level, in particular the plane in which the axial direction of the shaft extends, in a constructively simple manner. Thereby, packaging space can advantageously be saved.

Furthermore, the at least one connecting rod is mounted to the shaft on the first leg of the transmission portion, wherein the first leg of the transmission portion is located on a side of the transmission portion facing an actuation side of the shaft. In this context, the term "actuation side of the shaft" shall define a side of the shaft which is directly or indirectly coupled to an electric motor, in particular to a pinion of the electric motor, to drive the shaft. Thereby, a compact structure of the striking mechanism according to the invention can advantageously be achieved.

In addition, the shaft is rotatably mounted to said connecting rod via a bearing. The bearing can be configured as a roller bearing or a needle bearing. In a preferred embodiment of the invention the bearing is configured as a roller bearing. Thereby, a friction can advantageously be kept low during the rotary motion of the shaft between the shaft and the at least one con- necting rod.

Moreover, the present invention relates to a hand-held power tool, in particular a drill hammer and/or a chipping hammer, which comprises a striking mechanism according to the present invention and an electric motor to drive the striking mechanism. Thereby, a hand-held power tool with a compact and simple structure of the striking mechanism can advantageously be achieved.

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 drawing wherein a particular embodiment of the invention is disclosed as an illustrative example.

Fig. 1 shows a hand-held power tool that comprises a striking mechanism according to the invention in a schematic representation,

Fig. 2 shows a detail view of the striking mechanism according to the invention in a striking position in a schematic representation and

Fig. 3 shows a detail view of the striking mechanism according to the invention in a rear position in a schematic representation. Detailed Description of the Invention Figure 1 shows a hand-held power tool 38 that comprises a striking mechanism 10 according to the invention. The hand-held power tool 38 is configured as a drill hammer 40. Alternatively, the hand-held power tool 38 can also be configured as a chipping hammer (not shown). The drill hammer 40 comprises a housing 42 to accommodate the striking mechanism 10, a gear (not shown) and an electric motor 36. Moreover, the drill hammer 40 comprises a handle 44 which can be gripped by an operator using the drill hammer 40. The handle 44 essentially extends perpendicular to a main extension direction 46 of the drill hammer 40. Furthermore, the drill hammer 40 comprises a tool holder 48 to accommodate a tool 50. The tool holder 48 is located on a side 52 opposite to the handle 44 of the drill hammer 40. The drill hammer 40 further comprises a detachable accessory handle 54 which can also be gripped by the operator for a guidance of the drill hammer 40.

Figure 2 shows a detail view of the striking mechanism 10 according to the invention in a striking position. In the striking position a striking pulse is transmitted from the striking mechanism 10 to the tool 50. The striking pulse is produced in a well-known manner. The striking mechanism 10 comprises a hammer 12 (only schematically shown) and a piston 14 (only schematically shown) to produce the striking pulse, a shaft 16 to drive the piston 14 and a connecting rod 18 to connect the shaft 16 to the piston 14. To indirectly transmit the striking pulse to the tool 50, the striking mechanism 10 further comprises a striker 70 (only schematically shown) that is formed by a part which is separate from the hammer 12. The striker 70 directly contacts the tool 50 to transmit the striking pulse when the striking mechanism 10 is operated.

The shaft 16 is supported in the housing 42 of the drill hammer 40 via bearings (not shown). Moreover, the shaft 16 comprises a transmission portion 20 which is provided to convert a rotary motion of the shaft 16 into a reciprocating motion of the piston 14. The transmission portion 20 of the shaft 16 alternately moves the piston 14 along an axial direction 56 of the piston 14 from the striking position of the piston 14 into a rear position of the piston 14 (see figure 3) via the connecting rod 18 when the shaft 16 is rotated around a rotation axis 58 of the shaft 16. The axial direction 56 of the piston 14 is parallel to an axial direc- tion 24 of the shaft 16 and parallel to the main extension direction 46 of the drill hammer 40.

The transmission portion 20 of said shaft 16 is formed in one piece with said shaft 16, wherein the transmission portion 20 of the shaft 16 comprises at least one angled portion 22 that is angled in relation to an axial direction 24 of said shaft 16. In this condition, the at least one angled portion 22 of the transmission portion 20 is angled under an angle of 15° degrees to the axial direction 24 of the shaft 16. The angled arrangement of the transmission portion 20 in relation to the axial direction 24 of the shaft 16 results in a deflection of the shaft 16. To counteract this deflection of the shaft 16 the transmission portion 20 of the shaft 16 is essen- tially V-shaped. Thereby, the shaft 16 can be supported in the housing 42 of the drill hammer 40 with bearings (not shown) which are located in a plane that is parallel or coaxial to the axial direction 56 of the piston 14 and in which the rotation axis 58 of the shaft 16 is located.

The transmission portion 20 of the shaft 16 comprises a first leg 26 and a second leg 28 which are angled to each other and angled to the axial direction 24 of the shaft 16. Starting from an actuation side 32 of the shaft 16, the first leg 26 of the transmission portion 20 is angled to the axial direction 24 of the shaft 16 and to the second leg 28 of the transmission portion 20. The second leg 28 of the transmission portion 20 is further angled to the first leg 26 of the transmission portion 20 and then angled to the axial direction 24 of the shaft 16. The first leg 26 and the second leg 28 of the transmission portion 20 of the shaft 16 enclose an obtuse angle 30 of about 140° degrees.

The connecting rod 18 is mounted with one side 60 of the connecting rod 18 to the shaft 16 on the first leg 26 of the transmission portion 20, wherein the first leg 26 of the transmis- sion portion 20 is located on a side of the transmission portion 20 facing the actuation side 32 of the shaft 16. In this connection, an axial direction 72 of the connecting rod 18 is orientated perpendicular to an axial direction 74 of the first leg 26 of the transmission portion 20 of the shaft 16. Moreover, the connecting rod 18 is mounted with an opposite side 62 of the connecting rod 18 to a linkage portion 64 of the piston 14. The linkage portion 64 of the piston 14 is located on a side of the piston 14 which is located opposite to the hammer 12 when the striking mechanism 10 is in an installed state. The shaft 16 is rotatably mounted to the connecting rod 18 via a bearing 34 so that the shaft 16 can rotate relative to the connecting rod 18.

Figure 3 shows a detail view of the striking mechanism 10 according to the invention in the rear position of the piston 14. In the rear position of the piston 14 the shaft 16 is rotated about 180° degrees in comparison to the position of the shaft 16 shown in figure 2. The connecting rod 18 is deflected in the rear position of the striking mechanism 10 in its rearmost position in relation to a hammer tube 68 in which the piston 14 is axially supported.

A rotation of the shaft 16 causes an axial movement of the piston 14. The angled arrangement of the transmission portion 20 of the shaft 16 and the mounting of the connecting rod 18 on the transmission portion 20 and on the piston 14 results in a heterodyne movement of the connecting rod 18 when the shaft 16 is rotated. The connecting rod 18 is pivotably moved in a first plane perpendicular to the rotation axis 58 of the shaft 16 and is pivotably moved in a second plane which is perpendicular to the first plane. This movement of the connecting rod 18 causes a reciprocating motion of the piston 14 when the shaft 16 is rotated around the rotation axis of the shaft 16. During a rotation of the shaft 16 the axial direction 72 of the connecting rod 18 is always orientated perpendicular to the axial direction 74 of the first leg 26 of the transmission portion 20.

Thus the present invention may be practiced and/or configured otherwise than as specifically described above. Many changes, alternatives, variations, and equivalents to the various structures shown and described will be apparent to one skilled in the art. Accordingly, the present invention is not intended to be limited to the particular embodiments illustrated but is intended to cover all such alternatives, modifications, and equivalents as may be included within the spirit and broad scope of the invention as defined by the following claims. All patents, patent applications, and printed publications referred to herein are hereby incorporated by reference in their entirety.

Claims

1. A striking mechanism for a hand-held power tool, comprising:

a hammer (12) and a piston (14) to produce a striking pulse;

a shaft (16) to drive said piston (14);

and at least one connecting rod (18) to connect said shaft (16) to said piston (14);

wherein said shaft (16) comprises a transmission portion (20) which is provided to convert a rotary motion of said shaft (16) into a reciprocating motion of said piston (14).

2. The striking mechanism as defined in Claim 1, wherein said transmission portion

(20) of said shaft (16) is formed in one piece with said shaft (16).

3. The striking mechanism as defined in Claims 1 or 2, wherein said transmission portion (20) of said shaft (16) comprises at least one angled portion (22) that is angled in relation to an axial direction (24) of said shaft (16).

4. The striking mechanism as defined in one of the preceding Claims, wherein said transmission portion (20) of said shaft (16) is essentially V-shaped.

5. The striking mechanism as defined in Claim 4, wherein the transmission portion

(20) of said shaft (16) comprises a first leg (26) and a second leg (28) which are angled to each other and to said axial direction (24) of said shaft (16).

6. The striking mechanism as defined in Claim 5, wherein said first leg (26) and said second leg (28) of said transmission portion (20) of said shaft (16) enclose an obtuse angle

(30).

7. The striking mechanism as defined in Claim 5, wherein said at least one connecting rod (18) is mounted to said shaft (16) on said first leg (26) of said transmission portion (20), wherein said first leg (26) of said transmission portion (20) is located on a side of said transmission portion (20) facing an actuation side (32) of said shaft (16).

8. The striking mechanism as defined in one of the preceding Claims, wherein said shaft (16) is rotatably mounted to said connecting rod (18) via a bearing (34).

9. A hand-held power tool, comprising:

a striking mechanism as defined in one of the preceding Claims;

and an electric motor (36) to drive said striking mechanism.