Spindle lock and chipping mechanism for hammer drill

• US 6,550,546 B2
• Filed: 05/01/2001
• Issued: 04/22/2003
• Est. Priority Date: 06/03/1999
• Status: Expired due to Fees

• Current Assignee: One World Technologies (Techtronic Industries Company Limited)
• Original Assignee: One World Technologies (Techtronic Industries Company Limited)
• Inventors: Smith, Ralph E., Thurler, James E., Nemazi, John E.
• Primary Examiner(s): Rada, Rinaldi I.
• Assistant Examiner(s): TRUONG, THANH K
• Application Number:
  US09/846,827
• Publication Number:
  US 20020023763A1
• Time in Patent Office: 721 Days
• Field of Search: 173/48, 173/216, 173/47, 173/217, 173/109, 173/114, 173/205, 475/342
• US Class Current: 173/48
• CPC Class Codes: B25D 11/106 cam member and cam follower having the same shape B25D11/104 takes precedence
• CPC Class Codes: B25D 16/00 Portable percussive machines with superimposed rotation , the rotational movement of the output shaft of a motor being modified to generate axial impacts on the tool bit combined percussion and rotary drilling adapted for earth drilling E21B6/00
• CPC Class Codes: B25D 16/006 Mode changers; Mechanisms connected thereto
• CPC Class Codes: B25D 2211/064 Axial cams, e.g. two camming surfaces coaxial with drill spindle
• CPC Class Codes: B25D 2216/0046 Preventing rotation

Abstract

A hammer drill has a motor which drives an axially displaceable intermediate gear mounted in an intermediate gear arrangement. An impact mechanism is formed by including interacting impact cams between either the intermediate gear and the housing, or the motor armature shaft and the housing to generate a reciprocating motion on an output spindle or shaft. A spindle locking mechanism is included which causes an intermediate gear to be disengageable with respect to the output shaft, while still permitting the impact mechanism to be engaged. Such an arrangement allows the hammer drill to operate in a hammer-only or chipping mode.

Claims

1. A hammer drill capable of operation in a hammer drill mode, a drill-only mode, and a chipping mode comprising:

a housing;

a motor disposed in the housing and having a rotatable armature shaft, the armature shaft driving an armature pinion gear located at one end;

an axially displaceable output shaft having an outer end adapted to receive a drill chuck;

an output gear fixed about the output shaft to rotate coaxially therewith;

an intermediate gear reduction arrangement comprising at least a first gear engageable with the armature pinion, an axially displaceable second gear engageable to drive the output gear, and a rotation control mechanism for selectively moving the second gear into and out of driving engagement with the output gear;

an axially displaceable first cam mechanism to be driven by the armature shaft; and

a second cam mechanism affixed to the housing, the first and second cam mechanisms being engageable by selectively displacing the first cam mechanism to cause the first and second cam mechanisms to abut each other, wherein the first and second cam mechanisms are configured with respect to each other and the intermediate gear reduction arrangement to generate reciprocating motion in response to rotation of the armature shaft and cause the intermediate gear reduction arrangement to transmit the reciprocating motion to the output gear thereby axially reciprocating the output shaft irrespective of whether the second gear and the output gear are in rotational engagement;

wherein the intermediate gear reduction arrangement comprises a first planetary gear set having a sun provided by the armature pinion gear and an outer gear for driving a sun gear of a second planetary gear set, the second planetary gear set having a sun gear, a pinion gear and an outer gear, the outer gear driving the output gear to cause the output shaft to rotate, wherein the pinion gear of the second planetary gear set forms the axially displaceable second gear such that rotation of the output shaft can be prevented by selectively moving the axially displaceable pinion gear out of engagement with the outer gear of the second planetary gear set.

2. The hammer drill of claim 1 wherein the first impact cam mechanism is located on the armature pinion.

3. A hammer drill comprising:

a housing;

a motor disposed in the housing and having a rotatable armature shaft, the armature shaft driving an armature pinion gear located at one end;

an axially displaceable output shaft having an outer end adapted to receive a drill chuck;

an output gear fixed about the output shaft to rotate coaxially therewith;

an intermediate gear reduction arrangement comprising a first planetary gear set having a sun gear which is provided by the armature pinion gear, a pinion and an outer gear which drives the sun gear of a second planetary gear set, the second planetary gear set having a sun gear, a pinion and an outer gear for driving the output gear to cause the output shaft to rotate;

an axially displaceable first cam mechanism located on the armature pinion to be driven by the armature shaft; and

a second cam mechanism affixed to the housing, the first and second cam mechanisms being engageable by selectively displacing the first cam mechanism to cause the first and second cam mechanisms to abut each other, wherein the first and second cam mechanisms are configured with respect to each other and the first and second planetary gear sets to generate reciprocating motion of the outer gear in the second planetary gear set in response to rotation of the armature shaft which in turn transmits the reciprocating motion to the output gear thereby axially reciprocating the output shaft.

4. The hammer drill of claim 3 wherein the pinion gear of the second planetary gear set forms an axially displaceable second gear such that rotation of the output shaft can be prevented by selectively moving the axially displaceable pinion gear out of engagement with the outer gear of the second planetary gear set, thereby providing a chipping mode by allowing the intermediate gear reduction arrangement to transmit the reciprocating motion to the output gear irrespective of whether the outer gear of the second planetary gear set and the output gear are in rotational engagement.