Counterbalancing mechanism and power tool having same

Patent metadata

Field	Value
Publication number	US-11839964-B2
Application number	US-202217654133-A
Country	US
Kind code	B2
Filing date	Mar 9, 2022
Priority date	Mar 9, 2022
Publication date	Dec 12, 2023
Grant date	Dec 12, 2023

Abstract

A reciprocating power tool may include a driving system including a motor and a transmission received in a housing to drive a reciprocating mechanism. A counterbalance mechanism may be coupled between the driving system and the reciprocating mechanism. The counterbalance mechanism may include a rotating counterbalance mechanism including a first rotating counterweight member and a second rotating counterweight member coupled to an output gear of the driving system. The counterbalance mechanism may include a rocking counterweight member coupled between the output gear and the housing. The output gear may include a recessed portion in which the first rotating counterweight member and a clutching system are received.

First claim

What is claimed is:

1. A reciprocating power tool, comprising:
a housing;
a driving mechanism including a motor and a transmission mechanism received in the housing;
a reciprocating mechanism received in the housing, the reciprocating mechanism including a shaft that is coupled to an output gear of the driving mechanism, wherein the shaft is configured to reciprocate generally along an axis of operation in response to rotation of the output gear; and
a counterbalance mechanism, including:
a first counterbalance device coaxially arranged with respect to the output gear about a central axis of rotation and configured to rotate together with the output gear about the central axis of rotation; and
a second counterbalance device eccentrically coupled to the output gear and configured to perform a rocking motion with respect to the central axis of rotation in response to rotation of the output gear.

2. The reciprocating power tool of claim 1 , wherein
the first counterbalance device is configured to balance forces generated by reciprocating motion of the shaft along the axis of operation when a position of the first counterbalance device is in phase with a reciprocating motion of the shaft along the axis of operation; and
the second counterbalance device is configured to balance forces generated by the first counterbalance device when the position of the first counterbalance device is out of phase with reciprocating motion of the shaft along the axis of operation.

3. The reciprocating power tool of claim 1 , wherein the first counterbalance device includes:
a first rotating counterweight member positioned at a first side of the axis of operation and configured to rotate about the central axis of rotation together with the output gear; and
a second rotating counterweight member positioned at a second side of the axis of operation and configured to rotate about the central axis of rotation together with the output gear and the first rotating counterweight member.

4. The reciprocating power tool of claim 3 , wherein a center of mass of the first counterbalance device is balanced with respect to the axis of operation.

5. The reciprocating power tool of claim 3 , wherein the second counterbalance device includes:
a rocking counterweight member, including:
a weighted end portion positioned between the first rotating counterweight member and the second rotating counterweight member;
a slot formed in the weighted end portion, wherein the slot is eccentrically coupled to a hub portion of the output gear; and
an arm portion that is pivotably coupled to a housing of the reciprocating power tool.

6. The reciprocating power tool of claim 5 , further comprising a collar provided on the hub portion of the output gear, eccentrically positioned with respect to the central axis of rotation of the output gear, wherein the slot is slidably coupled on the collar such that the weighted end portion of the rocking counterweight member performs the rocking motion in response to rotation of the output gear.

7. The reciprocating power tool of claim 6 , further comprising a yoke having a first end portion thereof coupled to the shaft, and a second end portion thereof coupled to an eccentric pin provided on the hub portion of the output gear, coaxially arranged with the collar, such that the yoke is aligned with the axis of operation of the shaft and the second end portion of the yoke is positioned between the first counterbalance device and the second counterbalance device.

8. The reciprocating power tool of claim 5 , wherein the first rotating counterweight member is coupled to the hub portion of the output gear, and the coupled first rotating counterweight member and hub portion are received in a recess formed in a body portion of the output gear.

9. The reciprocating power tool of claim 8 , further comprising a clutching system coupled in the recess formed in the output gear, between the hub portion and the body portion of the output gear.

10. The reciprocating power tool of claim 9 , wherein the clutching system and the first rotating counterweight member of the first counterbalance device are fixed in the recess of the output gear and are configured to maintain synchronized operation of the rotation of the first counterbalance device about the central axis of rotation, rocking motion of the second counterbalance device with respect to the central axis of rotation, and the reciprocating motion of the shaft along the axis of operation.

11. A reciprocating power tool, comprising:
a housing;
a driving system including a motor and a transmission received in the housing;
a reciprocating mechanism received in the housing, the reciprocating mechanism including a shaft that is coupled to an output gear of the driving system, wherein the shaft is configured to reciprocate generally along an axis of operation in response to rotation of the output gear, wherein the output gear includes:
a body portion;
a recess formed in the body portion; and
a hub portion coupled in the recess, the hub portion being coupled to a central shaft defining an axis of rotation of the output gear;

at least one rotating counterweight member coupled to the hub portion and coupled in the recess, between the hub portion and the body portion of the output gear; and
a clutching system coupled in the recess of the output gear, between the hub portion and the body portion.

12. The reciprocating power tool of claim 11 , wherein the at least one rotating counterweight member, the hub portion and the body portion of the output gear are configured to rotate together about the axis of rotation in response to a driving force from the driving system.

13. The reciprocating power tool of claim 11 , wherein the at least one rotating counterweight member includes:
a first rotating counterweight member positioned at a first side of the axis of operation and configured to rotate about the axis of rotation together with the output gear; and
a second rotating counterweight member positioned at a second side of the axis of operation and configured to rotate about the axis of rotation together with the output gear and the first rotating counterweight member,
wherein one of the first rotating counterweight member or the second rotating counterweight member is coupled to the hub portion and received in the recess formed in the body portion of the output gear.

14. The reciprocating power tool of claim 13 , further comprising:
a rocking counterweight member having a first end portion pivotably coupled to the housing, and a second end portion thereof eccentrically coupled to the output gear,
wherein the rocking counterweight member is configured to perform a rocking motion in response to rotation of the output gear.

15. The reciprocating power tool of claim 14 , wherein
the first and second rotating counterweight members are configured to rotate together with the output gear, and to balance forces generated by reciprocating motion of the shaft along the axis of operation when the first and second rotating counterweight members are positioned in phase with reciprocating motion of the shaft along the axis of operation; and
the rocking counterweight member is configured to balance forces generated by the first and second rotating counterweight members when the first and second rotating counterweight members are positioned out of phase with reciprocating motion of the shaft along the axis of operation.

16. The reciprocating power tool of claim 14 , wherein the clutching system and the first rotating counterweight member fixed in the recess of the output g

Assignees

• Black & Decker Inc

Inventors

• Wang Yanchao

Classifications

• B23D51/161

  with dynamic balancing · CPC title

• B25F5/006 Primary

  Vibration damping means · CPC title

• B23D49/162

  Pad sawing devices · CPC title

• B23D49/165

  with means to move the saw blades in an orbital path · CPC title

• B23D51/16

  of drives or feed mechanisms for straight tools, e.g. saw blades, or bows · CPC title