Motor-driven machine tool

• US 8,162,727 B2
• Filed: 02/20/2008
• Issued: 04/24/2012
• Est. Priority Date: 04/19/2007
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Zaiser, Adolf
• Primary Examiner(s): Shakeri, Hadi
• Application Number:
  US12/374,537
• Publication Number:
  US 20090311952A1
• Time in Patent Office: 1,525 Days
• Field of Search: 451/356, 451/357, 451/159, 451/163, 451/344
• US Class Current: 451/357
• CPC Class Codes: B24B 23/04 with oscillating grinding tools; Accessories therefor
• CPC Class Codes: B24B 27/08 being portable
• CPC Class Codes: B24B 41/042 Balancing mechanisms
• CPC Class Codes: B27B 19/006 with oscillating saw blades; Hand saws with oscillating saw blades

Abstract

A motor-driven machine tool, in particular a hand-held power tool (1) includes a rotatably driveable tool (6), a drive shaft (4) which is driven by a drive unit (2), and an output shaft (5) on which the tool (6) is mounted. It is possible to transfer the rotational motion of the drive shaft (4) via an eccentric coupling device (7) to the output shaft (5). A mass-balancing device (10) provides for oscillation compensation and is operatively connected to at least one of the shafts (4, 5) and implements a compensation motion counter to the eccentric coupling motion.

Claims

1. A motor-driven machine tool (1) comprising:

a rotatably driveable tool (6);

a drive shaft (4) driven by a drive unit (2);

an output shaft (5) on which the tool (6) is mounted;

an eccentric coupling device (7) for transferring the rotational motion of the drive shaft (4) to the output shaft (5) via an eccentric coupling motion;

a mass-balancing device (10) for oscillation compensation, the mass-balancing device (10) being operatively connected to the drive shaft (4) and implementing a compensation motion counter to the eccentric coupling motion,

wherein the mass-balancing device (10) includes a mass-balancing member (11) and a first eccentric member (12) which is mounted on the drive shaft (4), the mass-balancing member (11) being operatively connected to the first eccentric member (12)

wherein the eccentric coupling device (7) includes a coupling member (8) and a second eccentric member (9) which is mounted on the drive shaft (4), the coupling member (8) being operatively connected to the second eccentric member (9), and

wherein the first and second eccentric members are designed as eccentric cams (9, 12) which are fixedly connected to the drive shaft (4), and wherein the coupling member (8) and mass-balancing member (11) bear against the contour of the respective eccentric cams (9, 12).

2. The machine tool as recited in claim 1, wherein the mass-balancing member (11) of the mass-balancing device (10) is rotatably supported on the output shaft (5).

3. The machine tool as recited in claim 1, wherein the mass-balancing member (11) of the mass-balancing device (10) is supported on a separate balancer shaft (15).

4. The machine tool as recited in claim 3, wherein the balancer shaft (15) is held on a housing (14) of the machine tool (1).

5. The machine tool as recited in claim 4, wherein the balancer shaft (15) is situated such that it is parallel to and offset from the output shaft (5).

6. The machine tool as recited in claim 1, wherein the eccentric cams (9, 12) are offset from each other by 180°

relative to the rotational axis (18) of the drive shaft (4).

7. The machine tool as recited in claim 1, wherein the coupling member (8) and the mass-balancing member (10) are each fork-shaped in design defining fork tines, the fork tines enclosing respective one of said first and second eccentric cams (9, 12).

8. The machine tool as recited in claim 1, wherein the distance between the mass-balancing member (11) and the first eccentric cam (12) is less than the distance between the coupling member (8) and the second eccentric cam (9).

9. The machine tool as recited in claim 1, wherein the drive shaft (4) and output shaft (5) are situated at an angle to one another.

10. The machine tool as recited in claim 9, wherein the coupling member (8) and the mass-balancing member (11) each include an offset contact section (8a, 11a) which is in contact with the respective one of the first and second eccentric cams (9, 12).

11. The machine tool as recited in claim 1, wherein the drive shaft (4) and output shaft (5) are situated parallel to one another.

12. The machine tool as recited in claim 1, wherein the eccentric coupling device (7) is retained on the output shaft (5) between the tool (6) and the mass-balancing device (10).

13. The machine tool as recited in claim 1, wherein the mass-balancing device (10) includes a reciprocating mass part (16) defining said mass-balancing member which is displaceably supported in a sliding guide (17) and is acted upon by the first eccentric cam (12).

14. The machine tool as recited in claim 13, wherein the sliding guide (17) makes it possible for the reciprocating mass part (16) to carry out an exclusively translatory displacement motion.

15. The machine tool as recited in claim 13, wherein the sliding guide (17) includes a slot link guide having a slot link track (20) and a guide pin which is guided therein.

16. The machine tool as recited in claim 1, wherein said machine tool is a hand-held power tool.