Clutch assembly for use with a circular saw

• US 6,295,910 B1
• Filed: 08/13/1999
• Issued: 10/02/2001
• Est. Priority Date: 08/13/1999
• Status: Expired due to Term

• Current Assignee: Credo Technology Corporation (Robert Bosch GmbH)
• Original Assignee: S-B Power Tool Company (Robert Bosch GmbH)
• Inventors: Holzer, Michael, Houben, Jan P., Childs, Daniel K.
• Primary Examiner(s): BRAY, WAYMOND D
• Application Number:
  US09/374,018
• Time in Patent Office: 781 Days
• Field of Search: 192/55.1, 192/56.1, 192/150, 192/48.3, 173/171, 173/176, 173/216, 835/43, 835/71, 836/981.1, 836/984.1, 814/76
• US Class Current: 83/698.11
• CPC Class Codes: B23D 47/12 of drives for circular saw blades
• CPC Class Codes: F16D 7/025 with flat clutching surfaces, e.g. discs
• CPC Class Codes: Y10T 83/8719 With transmission yieldable on overload
• CPC Class Codes: Y10T 83/9457 Joint or connection
• CPC Class Codes: Y10T 83/9464 For rotary tool

Abstract

A circular saw includes a clutch assembly to surround the rotating blade shaft of the saw. The blade shaft is rotated by a shaft having a gear at one end. The clutch assembly includes a clutch gear to engage with the rotating pinion. The clutch gear is held to the blade shaft by a shaft washer that has a frictional material laminated to one end. The shaft washer is pressed to the clutch gear by spring washers.

Claims

1. A circular saw comprising:

a rotating shaft having a radially extending pinion at one end;

a blade shaft to rotate a saw blade, the blade shaft having a first end and a second end wherein the blade is secured to the second end by a fastener, and

a clutch assembly surrounding the first end of the shaft wherein the clutch assembly includes;

a clutch gear having a center hole through which the first end of the clutch shaft extends and a gear arrangement around the outer perimeter to engage with the pinion, a first and a second spring means positioned on either side of the clutch gear, and a first and second shaft washer pressed against the clutch gear by the spring means, and

wherein the pinion rotates the clutch assembly to drive the blade shaft, and the clutch, and the clutch assembly overcomes the torque between the clutch gear and the clutch shaft when the clutch shaft is locked by the blade.

2. The circular saw according to claim 1 wherein the shaft washers have a core and at least one side coated with a frictional material to engage with the clutch gear.

3. The circular saw according to claim 2 wherein the frictional layer has a coefficent of friction between 0.15μ

and 0.6μ

.

4. The circular saw according to claim 1 further comprising a bearing positioned between the gear shaft and the gear clutch.

5. The circular saw according to claim 1 wherein the fastener is a bolt engaged in a hole longitudinally formed in the second of the clutch shaft.

6. The circular saw according to claim 1 further comprising a mechanism to secure to the first end of the clutch shaft to secure the clutch assembly against a ledge formed on the clutch shaft.

7. The circular saw according to claim 1 wherein the shaft washer is made of bronze or other material that does not weld to the clutch gear.

8. The circular saw according to claim 1 wherein the clutch assembly having at least one lamination of shaft washers and gear washers wherein the gear washers fits to the shaft to drive the shaft.

9. The circular saw according to claim 1 wherein the spring means is a spring washer.

23. The circular saw according to claim 6 wherein the mechanism is a press-fit washer.

10. A circular saw comprising:

a rotating shaft having a radially extending pinion at one end;

a blade shaft to rotate a saw blade, the blade shaft having a first end and a second end wherein the blade is secured to the second end by a fastener, and

a multi-surface clutch assembly surrounding the first end of the clutch shaft wherein the clutch assembly includes;

a clutch gear having a center hole through which the first end of the clutch shaft extends and a gear arrangement around the outer perimeter to engage with the pinion, a laminated washer assembly positioned on one side of the clutch gear having at least one gear washer sandwiched between shaft washers, and a gear washer and a spring means on the other side of the clutch gear, and

wherein the pinion rotates the clutch assembly to drive the blade shaft, and the clutch assembly, and the clutch assembly overcomes the torque between the clutch gear and the blade shaft when the clutch shaft is locked in position by the blade.

11. The circular saw according to claim 10 further comprising a bearing positioned between the gear shaft and the gear clutch.

12. The circular saw according to claim 10 wherein the fastener is a bolt engaged in a hole to longitudinally formed in the second end of the clutch shaft.

13. The circular saw according to claim 10 further comprising a mechanism secured to the first end of the clutch shaft to secure the clutch assembly against a ledge formed on the clutch shaft.

14. The circular saw according to claim 10 wherein the shaft washer is made of bronze or other material that will not weld to the clutch gear and gear washer.

15. The circular saw according to claim 10 wherein the clutch shaft includes a cylindrical lip at the one end of the clutch and the laminated washer assembly is positioned within the lip.

16. The circular saw according to claim 15 wherein the cylindrical lip includes notches formed on an inner surface and the gear washers include tabs formed along an outer perimeter of the gear washers wherein the tabs fit in the notches so that the gear washers rotate the gear clutch.

17. The circular saw according to claim 10 wherein the lamination has a coefficient of friction between 0.15μ

and 0.6μ

.

18. The circular saw according to claim 10 wherein the spring means is a spring washer.

24. The circular saw according to claim 13 wherein the mechanism is a press-fit washer.

19. A power tool comprising:

a rotating shaft;

a second shaft having a first end and a second end wherein a member is secured to the second end, and

a clutch assembly positioned between the rotating shaft and the second shaft wherein the rotating shaft rotates the clutch assembly drive the second shaft and the member and wherein the clutch assembly overcomes the torque between the clutch assembly and the second shaft when the member is locked while the rotating shaft rotates.

20. The power tool according to claim 19 where the clutch assembly comprises:

a clutch gear engaged with the rotating shaft;

a first and second shaft washer to drive the second shaft having a frictional layer engaging the clutch gear, and

a first and second spring means to bias the frictional layer against the clutch gear wherein the torque of the clutch gear overcomes a friction of the frictional layer when the member is locked.

21. The power tool according to claim 19 wherein the clutch assembly comprises:

a clutch gear engaged with the rotating shaft and

at least one lamination of gear washers and shaft washers wherein the clutch gear rotate the gear washers and the shaft washers drive the second shaft wherein the torque of the clutch gear overcomes a friction between the gear washers and shaft washers when the member is locked.

22. The power tool according to claim 19 wherein the power tool is a circular saw and the member is a blade.