Power tool having hammer mechanism
A power tool, such as a rotary hammer, includes a housing, an output shaft for mounting a tool accessary and a motor having a motor shaft that generates a rotational output for rotating and linearly hammering the output shaft. The rotational output of the motor shaft is coupled to the output shaft via a driving mechanism that includes a hammer mechanism. An intervening member is axially movable relative to the motor shaft and is operably coupled between the motor shaft and the hammer mechanism. The hammer mechanism and the output shaft are supported by a movable support that is axially movable relative to the housing. Because the output shaft and the driving mechanism are movable relative to the motor and the housing, which preferably includes handle, via the intervening member and the movable support during hammering operations, vibration generated during hammering operations can be dampened before reaching the housing.
1. A power tool configured to linearly drive a tool accessory, the power tool comprising:
a piston configured to be linearly reciprocated along a driving axis, the driving axis defining a front-rear direction of the power tool;
a cylindrical tool holder disposed in a front end portion of the power tool and configured to hold the tool accessory to be slidable along the driving axis;
a striking element configured to reciprocate along the driving axis in response to an air spring generated by reciprocating movement of the piston;
an intermediate element disposed between the tool accessory held by the tool holder and the striking element in the front-rear direction, the intermediate element being configured to transmit kinetic energy of the striking element to the tool accessory;
a cylindrical sleeve disposed within the tool holder so as to be slidable in the front-rear direction;
at least one elastic element disposed between the tool holder and a front end surface of the sleeve in the front-rear direction, the at least one elastic element being spaced apart from the intermediate element; and
a stopper disposed behind the sleeve in the front-rear direction,
wherein:
the intermediate element includes a first small-diameter part, a second small-diameter part and a large-diameter part disposed between the first and second small-diameter parts and having a larger diameter than the first and second small-diameter parts,
the sleeve is configured to hold and slidably guide the first small-diameter part of the intermediate element so as to be slidable along the driving axis and to abut on the large-diameter part from the front,
the stopper is configured to hold and slidably guide the second small-diameter part of the intermediate element so as to be slidable along the driving axis and to abut on the large-diameter part from the rear,
an annular gap is defined between an outermost surface of the large-diameter part and the cylindrical sleeve,
the tool holder and the sleeve respectively have a first abutment part and a second abutment part that are configured to abut against each other,
the first abutment part and the second abutment part are configured to be spaced apart from each other in the front-rear direction when a forward force is not being applied to the sleeve, and to abut against each other when a forward force is being applied to the sleeve via the intermediate element, and
at least one of a front end portion and a rear end portion of the at least one elastic element is chamfered.
2. The power tool as defined in claim 1 , wherein:
the stopper further includes a forward facing surface configured to block rearward movement of the intermediate element by abutting on the large-diameter part of the intermediate element from the rear at a rearmost position of the intermediate element; and
the sleeve is biased by the at least one elastic element and abuts on the stopper when a forward force is not being applied to the sleeve, and moves away from the stopper when a forward force is being applied to the sleeve via the intermediate element.
3. A power tool configured to linearly drive a tool accessory, the power tool comprising:
a piston configured to be linearly reciprocated along a driving axis, the driving axis defining a front-rear direction of the power tool;
a cylindrical tool holder disposed in a front end portion of the power tool and configured to hold the tool accessory to be slidable along the driving axis;
a striking element configured to reciprocate along the driving axis in response to an air spring generated by reciprocating movement of the piston;
an intermediate element disposed between the tool accessory held by the tool holder and the striking element in the front-rear direction, the intermediate element being configured to transmit kinetic energy of the striking element to the tool accessory;
a cylindrical sleeve disposed within the tool holder so as to be slidable in the front-rear direction; and
at least one elastic element disposed between the tool holder and a front end surface of the sleeve in the front-rear direction, the at least one elastic element being spaced apart from the intermediate element;
wherein:
the intermediate element includes a small-diameter part and a large-diameter part having a larger diameter than the small-diameter part,
the sleeve is configured to hold the small-diameter part of the intermediate element so as to be slidable along the driving axis and to abut on the large-diameter part from the front,
the tool holder and the sleeve respectively have a first abutment part and a second abutment part that are configured to abut against each other,
the first abutment part and the second abutment part are configured to be spaced apart from each other in the front-rear direction when a forward force is not being applied to the sleeve, and to abut against each other when a forward force is being applied to the sleeve via the intermediate element, and
at least one of a front end portion and a rear end portion of the at least one elastic element is chamfered.
4. The power tool as defined in claim 3 , wherein the sleeve includes:
a small-diameter part having the front end surface, and
a large-diameter part extending rearward from the small-diameter part and having a larger outer diameter than the small-diameter part.
5. The power tool as defined in claim 4 , wherein:
a shoulder part is provided on an inside of the tool holder,
the first abutment part is a rear surface of the shoulder part, and
the second abutment part is a front surface of the large-diameter part of the sleeve.
6. The power tool as defined in claim 5 , wherein each of the rear surface of the shoulder part and the front surface of the large-diameter part of the sleeve is a conical surface having a diameter that increases toward the rear.
7. The power tool as defined in claim 6 , further comprising:
a stopper disposed behind the sleeve and configured to block rearward movement of the intermediate element by abutting on the large-diameter part of the intermediate element from the rear;
wherein the sleeve is biased by the at least one elastic element and abuts on the stopper.
8. The power tool as defined in claim 7 , wherein the at least one elastic element is spaced apart from the intermediate element in a radial direction of the tool holder.
9. The power tool as defined in claim 8 , further comprising:
a catcher disposed behind the stopper and configured to catch a front end portion of the striking element.
10. The power tool as defined in claim 3 , wherein the at least one elastic element has a dimension in the front-rear direction that is larger than a dimension in a thickness direction.
11. The power tool as defined in claim 3 , wherein the at least one elastic element has a sectional shape in a plane orthogonal to the driving axis that is not uniform in the front-rear direction.
12. The power tool as defined in claim 11 , wherein the at least one elastic element has an annular shape and has recesses and protrusions each extending in the front-rear direction.
13. The power tool as defined in claim 11 , wherein the at least one elastic element is configured such that an area of contact with the sleeve changes as the at least one elastic element elastically deforms.
14. The power tool as defined in claim 3 , wherein a radially outer surface of the at least one elastic member contacts an inner circumferential surface of the tool holder.
15. The power tool as defined in claim 3 , wherein an inner diameter of the at least one elastic member is larger than the diameter of the small-diameter part of the intermediate element.
16. The power tool as defined in claim 3 , wherein the at least one elastic element is disposed between the tool holder and a forwardmost end surface of the sleeve in the front-rear direction.
17. The power tool as defined in claim 3 , further comprising an oil seal disposed between the tool holder and the at least one elastic element in the front-rear direction.
18. The power tool as defined in claim 3 , wherein:
a stopper is disposed behind the sleeve in the front-rear direction,
the stopper includes a forward facing surface configured to block rearward movement of the intermediate element by abutting on the large-diameter part of the intermediate element from the rear at a rearmost position of the intermediate element; and
the sleeve is biased by the at least one elastic element and abuts on the stopper when a forward force is not being applied to the sleeve, and moves away from the stopper when a forward force is being applied to the sleeve via the intermediate element.
19. A power tool configured to linearly drive a tool accessory, the power tool comprising:
a piston configured to be linearly reciprocated along a driving axis, the driving axis defining a front-rear direction of the power tool;
a cylindrical tool holder disposed in a front end portion of the power tool and configured to hold the tool accessory to be slidable along the driving axis;
a striking element configured to reciprocate along the driving axis in response to an air spring generated by reciprocating movement of the piston;
an intermediate element disposed between the tool accessory held by the tool holder and the striking element in the front-rear direction, the intermediate element being configured to transmit kinetic energy of the striking element to the tool accessory;
a cylindrical sleeve disposed within the tool holder so as to be slidable in the front-rear direction;
at least one elastic element disposed between the tool holder and a front end surface of the sleeve in the front-rear direction; and
a stopper disposed behind the sleeve in the front-rear direction,
wherein:
the intermediate element includes a first small-diameter part, a second small-diameter part and a large-diameter part disposed between the first and second small-diameter parts and having a larger diameter than the first and second small-diameter parts,
the sleeve is configured to hold and slidably guide the first small-diameter part of the intermediate element so as to be slidable along the driving axis and to abut on the large-diameter part from the front,
the stopper is configured to hold and slidably guide the second small-diameter part of the intermediate element so as to be slidable along the driving axis and to abut on the large-diameter part from the rear,
an annular gap is defined between an outermost surface of the large-diameter part and the cylindrical sleeve,
the first abutment part and the second abutment part are configured to be spaced apart from each other in the front-rear direction when a forward force is not being applied to the sleeve, and to abut against each other when a forward force is being applied to the sleeve via the intermediate element,
the at least one elastic member is configured to bias the sleeve rearward at least when the first abutment part of the tool holder is abutting the second abutment part of the sleeve, and
at least one of a front end portion and a rear end portion of the at least one elastic element is chamfered.
20. The power tool as defined in claim 19 , wherein the first abutment surface of the tool holder is rearward of the at least one elastic member.