Rotary hammer

• US 9,630,307 B2
• Filed: 08/20/2013
• Issued: 04/25/2017
• Est. Priority Date: 08/22/2012
• Status: Active Grant

• Current Assignee: Milwaukee Electric Tool Corporation (Techtronic Industries Company Limited)
• Original Assignee: Milwaukee Electric Tool Corporation (Techtronic Industries Company Limited)
• Inventors: Ludy, Benjamin, Richards, Daryl S.
• Primary Examiner(s): TRUONG, THANH K
• Assistant Examiner(s): Fry, Patrick
• Application Number:
  US13/971,131
• Publication Number:
  US 20140054057A1
• Time in Patent Office: 1,344 Days
• Field of Search: 173 47, 173205
• CPC Class Codes: B25D 11/04 in which the tool bit or anvil is hit by an impulse member
• CPC Class Codes: B25D 11/12 comprising a crank mechanism
• CPC Class Codes: B25D 11/125 with a fluid cushion between the crank drive and the striking body
• CPC Class Codes: B25D 16/006 Mode changers; Mechanisms connected thereto
• CPC Class Codes: B25D 2216/0015 Tools having a percussion-only mode
• CPC Class Codes: B25D 2216/0023 Tools having a percussion-and-rotation mode
• CPC Class Codes: B25D 2216/0038 Tools having a rotation-only mode
• CPC Class Codes: B25D 2216/0046 Preventing rotation
• CPC Class Codes: B25D 2216/0069 Locking means

Abstract

A rotary hammer is adapted to impart axial impacts to a tool bit. The rotary hammer includes a motor, a spindle coupled to the motor for receiving torque from the motor, and a piston at least partially received within the spindle for reciprocation therein. A crank hub is coupled to the motor for receiving torque from the motor. The crank hub defines a rotational axis and includes a socket offset from the rotational axis. A pin includes a first portion at least partially received within the socket and a second portion fixed to the piston. The first portion of the pin is both pivotable within the socket and axially displaceable relative to the socket in response to rotation of the crank hub for reciprocating the piston between a forward-most position within the spindle and a rearward-most position within the spindle.

Claims

1. A rotary hammer adapted to impart axial impacts to a tool bit, the rotary hammer comprising:

a motor including an output shaft that defines a motor axis;

a spindle coupled to the motor for receiving torque from the motor;

a piston at least partially received within the spindle for reciprocation therein;

a crank hub coupled to the motor for receiving torque from the motor, the crank hub defining a rotational axis coaxial with the motor axis and including a socket offset from the rotational axis;

a pin including a first portion at least partially received within the socket and a second portion fixed to the piston to inhibit relative movement between the pin and the piston, the first portion of the pin being both pivotable within the socket and axially displaceable relative to the socket in response to rotation of the crank hub for reciprocating the piston between a forward-most position within the spindle and a rearward-most position within the spindle; and

a mode selection mechanism including a first coupler movable along the rotational axis to selectively connect and disconnect the spindle and the motor, and a second coupler movable along the rotational axis to selectively connect and disconnect the crank hub and the motor.

2. The rotary hammer of claim 1, wherein the first portion includes a generally spherical end.

3. The rotary hammer of claim 2, wherein the spherical end includes a first diameter, and wherein the socket includes a second diameter nominally larger than the first diameter of the spherical end.

4. The rotary hammer of claim 1, wherein the piston includes an aperture in which the pin is received, and wherein the pin is fixed relative to the piston using an interference fit with the aperture.

5. The rotary hammer of claim 4, wherein the pin includes a shoulder limiting an extent to which the pin is received within the aperture, and wherein the shoulder is engaged with a peripheral surface of the piston surrounding the aperture.

6. The rotary hammer of claim 5, wherein the second portion of the pin is threaded, and wherein the rotary hammer further includes a fastener threaded to the second portion of the pin.

7. The rotary hammer of claim 6, wherein the piston is clamped between the shoulder and the fastener.

8. The rotary hammer of claim 1, wherein one revolution of the crank hub can be divided into at least a first rotational position, a second rotational position offset 90 degrees from the first rotational position, a third rotational position offset 180 degrees from the first rotational position, and a fourth rotational position offset 270 degrees from the first rotational position.

9. The rotary hammer of claim 8, wherein the forward-most position of the piston coincides with the first rotational position, and the rearward-most position coincides with the third rotational position.

10. The rotary hammer of claim 8, wherein the socket defines a central axis parallel with the rotational axis of the crank hub, and wherein the pin defines a longitudinal axis that is substantially coaxial with the central axis in the first and third rotational positions of the crank hub.

11. The rotary hammer of claim 10, wherein the pin is pivoted relative to the crank hub in the second and fourth rotational positions of the crank hub to define an oblique included angle between the central and longitudinal axes of the socket and the pin, respectively.

12. The rotary hammer of claim 11, wherein the oblique included angle is about 29 degrees or less.

13. The rotary hammer of claim 11, wherein the oblique included angle has a minimum value coinciding with the first and third rotational positions of the crank hub, and wherein the oblique included angle has a maximum value coinciding with the second and fourth rotational positions of the crank hub.

14. The rotary hammer of claim 1, further comprising a striker received within the spindle for reciprocation in response to reciprocation of the piston.

15. The rotary hammer of claim 14, further comprising an anvil received within the spindle and positioned between the striker and the tool bit, the anvil imparting axial impacts to the tool bit in response to reciprocation of the striker.

16. The rotary hammer of claim 14, wherein the piston is hollow and defines an interior chamber in which the striker is received.

17. The rotary hammer of claim 1, wherein the piston defines a reciprocating axis, and wherein the piston rotates about the reciprocating axis as the pin pivots within the socket.

18. The rotary hammer of claim 1, wherein the mode selection mechanism is configured to switch the rotary hammer between a drill mode, in which torque from the motor is not transferred to the crank hub, a hammer-drill mode, in which both the crank hub and the spindle receive torque from the motor, and a hammer-only mode, in which torque from the motor is not transferred to the spindle.

19. A rotary hammer adapted to impart axial impacts to a tool bit, the rotary hammer comprising:

a motor defining a motor axis;

a spindle coupled to the motor for receiving torque from the motor;

an impact mechanism at least partially received within the spindle for imparting the axial impacts to the tool bit;

a reciprocation mechanism for converting torque received from the motor to a reciprocating force acting on the impact mechanism, at least a portion of the reciprocation mechanism defining a rotational axis coaxial with the motor axis; and

a mode selection mechanism including a first coupler movable along the rotational axis to selectively connect and disconnect the spindle and the motor, and a second coupler movable along the rotational axis to selectively connect and disconnect the reciprocation mechanism and the motor.