PORTABLE IMPACT WRENCH

• US 3,847,229 A
• Filed: 05/24/1973
• Issued: 11/12/1974
• Est. Priority Date: 06/16/1972
• Status: Expired due to Term

• Current Assignee: Hubertus Karl, Jorg Falchle, Karl Wanner, Wolfgang Schmidt
• Original Assignee: Hubertus Karl, Jorg Falchle, Karl Wanner, Wolfgang Schmidt
• Inventors: Wanner, Karl, Schmid, Wolfgang, Karl, Hubertus, Falchle, Jorg
• Primary Examiner(s): Purser, Ernest R.
• Assistant Examiner(s): Pate, III, William F.
• Application Number:
  US05/363,711
• Time in Patent Office: 537 Days
• Field of Search: 173/47,48,110,111,109
• US Class Current: 173/48
• 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 2211/003 Crossed drill and motor spindles
• CPC Class Codes: B25D 2211/068 Crank-actuated impulse-driving mechanisms

Abstract

A portable impact wrench wherein a crank assembly reciprocates a cylinder which propels an impeller against the rear end of a tool holder in response to each of its forward strokes. The tool holder is rotatable stepwise in a single direction by a group of three sleeves the first of which is rotatable on but moves lengthwise with the cylinder and is normally held against rotation by a claw clutch one element of which is fixed to the housing. An intermediate sleeve has inclined teeth or threads meshing with complementary threads or teeth of the first sleeve so that the intermediate sleeve rotates back and forth in response to rearward and forward movements of the first sleeve. A third sleeve is rotatable in the housing and is connected with the intermediate sleeve by a one-way clutch. The tool holder is movable axially in but shares all angular movements of the third sleeve. Another element of the claw clutch is biased against the fixed element by a helical spring and has axially parallel teeth mating with complementary teeth of the first sleeve so that the latter can move axially but is normally held against rotation. The bias of the spring may be changed, terminated and/or assisted by a projection which can be manipulated by hand so that the user can apply his muscle power in order to increase the resistance of the other clutch element to disengagement from the fixed clutch element when the tool holder resists rotation with the third sleeve. When the claw clutch is disengaged and the cylinder continues to move forwardly and rearwardly, the intermediate sleeve rotates the first sleeve.

Claims

1. In a portable power tool, particularly in an impact wrench or drill, a combination comprising a housing;

drive means provided in said housing and including an output member movable forwardly and rearwardly;

a tool holder rotatably and reciprocably mounted in said housing in front of said output member;

impeller means provided in said housing and operative to strike against said tool holder in response to forward movements of said output member; and

means for normally rotating said tool holder in response to forward movements of said output member, including an input element rotatably surrounding and movable with said output member, blocking means provided in said housing for normally holding said input element against rotation, an intermediate element rotatably mounted in said housing, said elements having tubular portions telescoped into each other and provided with mating inclined teeth or threads so that the forward and rearward movements of said input element result in rotation of said intermediate element in opposite directions, an output element rotatably mounted in said housing, said tool holder being movable axially relative to and being rotatable with said output element, and one-way clutch means provided between said intermediate element and said output element to rotate said tool holder by way of said output element in response to forward movements of said input element.

2. A combination as defined in claim 1, wherein said drive means further comprises an electric motor having a rotor and a crank assembly connected between said rotor and said output member for converting the rotary movements of said rotor into reciprocatory movements of said output member.

3. A combination as defined in claim 1, wherein said blocking means comprises a clutch having a first clutch element rigid with said housing, a second clutch element rotatably and axially movably mounted in said housing, said clutch elements having complementary male and female portions, and means for biasing said second clutch element against said first clutch element, said second clutch element having first axially parallel teeth and said input element having second axially parallel teeth mating with said first teeth so that said input element is rotatable with said first clutch element relative to said output member only when said second clutch element is disengaged from said first clutch element.

4. A combination as defined in claim 3, wherein said means for biasing comprises resilient means.

5. A combination as defined in claim 3, wherein said means for biasing comprises a manually operable biasing device.

6. A combination as defined in claim 5, wherein said means for biasing further comprises prestressed resilient means and said biasing device comprises means for changing the stressing of said resilient means and for disengaging said resilient means from said second clutch element.

7. A combination as defined in claim 3, wherein said male portions of said clutch elements comprise conical claws.

8. A combination as defined in claim 7, wherein each of said clutch elements is an annulus and said annuli having adjacent end faces provided with said claws.

9. A combination as defined in claim 8, wherein said means for biasing comprises a prestressed spring provided in said housing and arranged to normally bear against said second clutch element so as to urge the claws thereof into engagement with the claws of said first clutch element, and a biasing device having a projection movable relative to said housing to thereby change the stressing of said spring or to disengage said spring from said second clutch element.

10. A combination as defined in claim 9, wherein said biasing means further comprises a handle which is accessible from without said housing and is operable by hand to thereby move said projection relative to said housing.

11. A combination as defined in claim 9, wherein said projection is movable by hand to at least one position in which the force furnished by the hand maintains the claws of said second clutch element in engagement with the claws of said first clutch element.

12. A combination as defined in claim 11, wherein said biasing device further comprises a handle rotatably mounted in said housing and being operable by hand to thereby move said projection relative to said housing and to maintain said projection in said one position.

13. A combination as defined in claim 12, wherein said biasing device further comprises at least one stop provided in said housing and cooperating with locking means provided on said handle to maintain said handle in a selected angular position, said handle being movable radially of said clutch elements to thereby disengage said locking means from said stop and further comprising resilient means yieldably opposing the movement of said handle radially of said clutch elements in a direction to disengage said locking means from said stop.