Impact tool with collapsible member to compensate for thermal expansion

Patent metadata

Field	Value
Publication number	US-12304034-B2
Application number	US-202418439466-A
Country	US
Kind code	B2
Filing date	Feb 12, 2024
Priority date	Aug 25, 2016
Publication date	May 20, 2025
Grant date	May 20, 2025

Abstract

An impact power tool includes a motor, an output shaft to which a tool bit is attachable for performing work on a workpiece, and an impact mechanism disposed between the motor and the output shaft for converting a continuous torque output from the motor to discrete pulses of torque upon the output shaft, the impact mechanism including a cylinder assembly, a cavity defined within the cylinder assembly containing a hydraulic fluid, and a collapsible member having a first end and a second end opposite the first end. The collapsible member is maintained in a shape coinciding with that of the cavity by fitment within the cavity, with the first and second ends being disconnected from each other. The collapsible member is collapsible to compensate for thermal expansion of the hydraulic fluid during operation of the impact mechanism.

First claim

What is claimed is:

1. An impact power tool comprising:
a motor;
an output shaft to which a tool bit is attachable for performing work on a workpiece; and
an impact mechanism disposed between the motor and the output shaft for converting a continuous torque output from the motor to discrete pulses of torque upon the output shaft, the impact mechanism including
a cylinder assembly,
a cavity defined within the cylinder assembly containing a hydraulic fluid, and
a collapsible member having a first end and a second end opposite the first end, the collapsible member being maintained in a shape coinciding with that of the cavity by fitment within the cavity, with the first and second ends being disconnected from each other; and

wherein the collapsible member is collapsible to compensate for thermal expansion of the hydraulic fluid during operation of the impact mechanism.

2. The impact power tool of claim 1 , wherein the collapsible member contains a gas.

3. The impact power tool of claim 2 , wherein the gas is air.

4. The impact power tool of claim 1 , wherein the cavity is a first cavity and the cylinder assembly includes a cylinder defining a second cavity, and wherein the impact mechanism further includes a plate disposed between the first cavity and the second cavity to retain the collapsible member within the first cavity.

5. The impact power tool of claim 1 , wherein the collapsible member is made of an elastomer.

6. An impact power tool comprising:
a motor;
an output shaft to which a tool bit is attachable for performing work on a workpiece; and
an impact mechanism disposed between the motor and the output shaft for converting a continuous torque output from the motor to discrete pulses of torque upon the output shaft, the impact mechanism including
a cylinder assembly including a cylinder and an end cap attached for co-rotation with the cylinder,
a first cavity at least partly defined by an interior surface of the cylinder and containing a hydraulic fluid,
a blade extending from the output shaft to abut the interior surface of the cylinder,
a second cavity in communication with the first cavity, and
a collapsible member positioned within the second cavity, the collapsible member having a first end and a second end, with the first and second ends being disconnected from each other;

wherein the collapsible member is collapsible to compensate for thermal expansion of the hydraulic fluid during operation of the impact mechanism.

7. The impact power tool of claim 6 , wherein the first and second ends are seamless.

8. The impact power tool of claim 6 , wherein the collapsible member contains a gas.

9. The impact power tool of claim 6 , wherein the impact mechanism further includes a plate disposed between the first cavity and the second cavity, the plate including apertures communicating the hydraulic fluid between the first and second cavities.

10. The impact power tool of claim 6 , wherein the collapsible member is bent into a curved shape corresponding with a shape of the second cavity.

11. The impact power tool of claim 6 , wherein the collapsible member is made of an elastomer.

12. The impact power tool of claim 6 , wherein the second cavity is defined by the end cap.

13. An impact power tool comprising:
a motor;
an output shaft to which a tool bit is attachable for performing work on a workpiece; and
an impact mechanism disposed between the motor and the output shaft for converting a continuous torque output from the motor to discrete pulses of torque upon the output shaft, the impact mechanism including
a cylinder assembly,
a cavity defined within the cylinder assembly containing a hydraulic fluid, and
a collapsible member having a first end, a second end opposite the first end, and a gas trapped within an interior volume of the collapsible member defined between the first and second ends,

wherein the collapsible member is bent into a curved shape, with the first and second ends being disconnected from each other; and
wherein the collapsible member is collapsible to compensate for thermal expansion of the hydraulic fluid during operation of the impact mechanism.

14. The impact power tool of claim 13 , wherein the curved shape of the collapsible member is maintained by fitment of the collapsible member within the cavity.

15. The impact power tool of claim 13 , wherein the first and second ends are seamless.

16. The impact power tool of claim 13 , wherein the gas is air.

17. The impact power tool of claim 13 , wherein the cavity is a first cavity and the cylinder assembly includes a cylinder defining a second cavity and a cap coupled to the cylinder for co-rotation therewith.

18. The impact power tool of claim 17 , wherein the impact mechanism further includes a plate disposed between the first cavity and the second cavity, the plate including apertures communicating the hydraulic fluid between the first and second cavities.

19. The impact power tool of claim 18 , wherein the collapsible member is made of an elastomer.

20. The impact power tool of claim 18 , further comprising a transmission positioned between the motor and the impact mechanism such that the cylinder is coupled for co-rotation with an output of the transmission,
wherein the impact mechanism further includes
a camshaft coupled for co-rotation with the cylinder,
a pair of blades extending from the output shaft to abut an interior surface of the cylinder, and
a pair of ball bearings positioned between the camshaft and the pair of blades.

Assignees

• Milwaukee Electric Tool Corp

Inventors

• Carlson Mitchell
• Hu Ding Feng
• Yu Zhiqiang
• Zeng Fanbin

Classifications

• B25F5/02

  Construction of casings, bodies or handles {(B25F5/006, B25F5/008 take precedence)} · CPC title

• B25B23/0007

  Connections or joints between tool parts · CPC title

• B25B21/026 Primary

  Impact clutches · CPC title