Reciprocating drive mechanism and power tool including the same

Patent metadata

Field	Value
Publication number	US-9700949-B2
Application number	US-201414449855-A
Country	US
Kind code	B2
Filing date	Aug 1, 2014
Priority date	Aug 2, 2013
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

A reciprocating drive mechanism for a power tool includes a rotatably mounted transmission shaft that has a first central axis, a spindle with a spindle body, and a counterweight for linearly reciprocating motion under the guide of at least one guiding rod. A wobble plate is mounted on the transmission shaft and includes a first arm and second arms extending in opposite directions. The first arm and second arms are configured to cooperate with the spindle and the counterweight respectively so that, upon rotation of the transmission shaft, the first and second arms of the wobble plate drive the spindle and the counterweight to reciprocate in opposite directions parallel to the second central axis. An angle is formed between the extending direction of the first arm and the second arm and a plane defined by the first central axis and the second central axis.

First claim

The invention claimed is:

1. A reciprocating drive mechanism for a power tool, comprising:
a rotatably mounted transmission shaft having a first central axis;
a spindle comprising a spindle body having a second central axis parallel with the first central axis;
a counterweight configured for linearly reciprocating motion guided by at least one guiding rod, the counterweight having a counterweight body; and
a wobble plate mounted on the transmission shaft and comprising a first arm and a second arm,
wherein a length of the first arm and a length of the second arm extend along an arm axis,
wherein the length of the first arm and the length of the second arm extend lengthwise in opposite directions, relative to the transmission shaft, along the arm axis,
wherein the first arm is configured to cooperate with the spindle and the second arm is configured to cooperate with the counterweight so that, upon rotation of the transmission shaft, the first arm drives the spindle and the second arm drives the counterweight such that the spindle and the counterweight reciprocate in opposite directions parallel to the second central axis, and
wherein the arm axis intersects a plane that is defined by the first central axis and the second central axis.

2. The reciprocating drive mechanism according to claim 1 , wherein the counterweight body is disposed between the spindle and the wobble plate and shaped to mate with a space between the spindle and the wobble plate so that the gravity center of the counterweight is close to the gravity center of the spindle.

3. The reciprocating drive mechanism according to claim 1 , wherein:
the spindle further comprises a spindle projection extending radially outwardly from the spindle body, and
the counterweight further comprises a counterweight projection extending radially outwardly from the counterweight body.

4. The reciprocating drive mechanism according to claim 3 , wherein the spindle body is guided through at least one bushing and the spindle projection is guided through at least one guide plate member so that the spindle is configured to be driven to reciprocate in a substantially linear direction by the wobble plate, the at least one bushing and the at least one guide plate member being fixed relative to the power tool body.

5. The reciprocating drive mechanism according to claim 3 , wherein:
ends of the spindle projection are operatively connected with ends of the first arms,
ends of the counterweight projection are operatively connected with ends of the second arms,
the ends of the spindle projection and the ends of the counter projection are configured with bores,
the ends of the first arms are configured as spheres rotatably accommodated in the bores of the ends of the spindle projection to drive the spindle to move, and
the ends of the second arms are configured as spheres rotatably accommodated in the bores of the ends of the counterweight projection to drive the counterweight to move.

6. The reciprocating drive mechanism according to claim 1 , further comprising a gear transmission including a large-diameter gear and a small-diameter gear meshing with each other, the large-diameter gear being rotationally fixed to the transmission shaft, and the small-diameter gear being driven by a power source to rotate the large-diameter gear and the transmission shaft.

7. The reciprocating drive mechanism according to claim 1 , wherein the counterweight is configured with at least one hole configured to slidably receive the at least one guiding rod so that the counterweight is configured to be guided to reciprocate in a substantially linear direction under the guide of the at least one guiding rod, the at least one guiding rod being disposed in parallel with the extending direction of the spindle.

8. The reciprocating drive mechanism according to claim 7 , wherein the hole is located at or close to the gravity center of the counterweight.

9. The reciprocating drive mechanism according to claim 1 , wherein the arm axis intersects the plane at an angle that is between 10° to 45°.

10. A power tool, comprising:
a reciprocating drive mechanism including:
a rotatably mounted transmission shaft having a first central axis;
a spindle comprising a spindle body having a second central axis parallel with the first central axis;
a counterweight configured for linearly reciprocating motion guided by at least one guiding rod, the counterweight having a counterweight body; and
a wobble plate mounted on the transmission shaft and comprising a first arm and a second arm,
wherein the length of the first arm and the length of the second arm extend along an arm axis,
wherein the length of the first arm and the length of the second arm extend lengthwise in opposite directions, relative to the transmission shaft, along the arm axis,
wherein the first arm is configured to cooperate with the spindle and the second arm is configured to cooperate with the counterweight so that, upon rotation of the transmission shaft, the first arm drives the spindle and the second arm drives the counterweight such that the spindle and the counterweight reciprocate in opposite directions parallel the second central axis,
wherein the arm axis intersects a plane that is defined by the first central axis and the second central axis.

11. The power tool according to claim 10 , wherein the power tool is configured as a wobble-driven reciprocating saw.

Assignees

• Bosch Power Tools (China) Co Ltd
• Bosch Gmbh Robert

Inventors

• Wang Yanchao

Classifications

• B23D49/162

  Pad sawing devices · CPC title

• B23D51/16 Primary

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

• B23D51/161 Primary

  with dynamic balancing · CPC title