Impact tool with gas spring
An impact power tool including a housing, a motor supported by the housing, a gear assembly driven by the motor, and an impact assembly driven by the gear assembly. The impact mechanism includes a camshaft, an anvil, and a hammer. The camshaft is coupled to the output of gear assembly and rotates about a rotation axis. The anvil is rotatably supported by the housing and can receive a tool bit. The hammer rotates and moves axially along the camshaft and is configured to selectively impact the anvil. When a reaction torque is greater than a threshold value is applied to the anvil, the hammer moves in a first direction away from the anvil and simultaneously compresses a compressible fluid. At a maximum distance from the anvil, the compressible fluid begins to exert a restoring force on the hammer and moves the hammer in a second direction towards the anvil.
1 . An impact power tool comprising:
a housing;
a motor disposed within the housing;
a gear assembly disposed within the housing, the gear assembly driven by an output of the motor; and
an impact mechanism disposed within the housing, the impact mechanism driven by an output of the gear assembly, the impact mechanism comprising:
a camshaft configured to rotate about a rotational axis,
an anvil rotatably supported by the housing, the anvil including a drive portion able to receive a tool bit,
a hammer coupled to the camshaft, the hammer is configured to rotate about the rotational axis and move axially along the camshaft to selectively apply rotational impacts to the anvil, and
a chamber surrounding the camshaft and able to receive a portion of the hammer, the chamber filled with a compressible fluid;
wherein the chamber includes a vent comprising a passage extending radially through a wall of the chamber,
wherein the hammer is configured to cover the vent, thereby sealing the chamber from atmospheric conditions, and to compress the compressible fluid as the hammer moves in a first direction away from the anvil,
wherein the compressible fluid applies a biasing force against the hammer in a second direction opposite to the first direction in response to the hammer reaching a maximum axial displacement from the anvil, and
wherein the hammer is configured to uncover the vent, thereby exposing the chamber to atmospheric conditions as the hammer moves in the second direction.
2 . The impact power tool of claim 1 , wherein the camshaft extends through the chamber.
3 . The impact power tool of claim 1 , wherein the vent is one of a plurality of vents configured to selectively fluidly connect an interior of the chamber with atmospheric conditions.
4 . The impact power tool of claim 1 , wherein the hammer includes a sealing feature insertable into the chamber to create a fluid tight seal.
5 . The impact power tool of claim 1 , wherein the compressible fluid is air.
6 . The impact power tool of claim 1 , wherein the impact mechanism includes a mechanical spring positioned within the chamber and configured to bias the hammer in the second direction.
7 . An impact power tool comprising:
a housing, the housing including a sealed region filled with a compressible fluid;
a motor disposed within the housing;
a gear assembly disposed within the housing, the gear assembly driven by an output of the motor;
an impact mechanism disposed within the housing, the impact mechanism driven by an output of the gear assembly, the impact mechanism comprising:
a camshaft coupled to the output of the gear assembly, the camshaft configured to rotate about a rotational axis;
an anvil rotatably supported by the housing, the anvil including a drive portion able to receive a tool bit, and
a hammer coupled to the camshaft, the hammer configured to rotate about the rotational axis and move axially along the camshaft to selectively apply rotational impacts to the anvil;
wherein the hammer includes an inner periphery adjacent the camshaft, an outer periphery adjacent an inner wall of the housing, and a seal on the outer periphery of the hammer such that the seal contacts the inner wall of the housing to define a boundary of the sealed region,
wherein the hammer is configured to compress the compressible fluid in the sealed region of the housing as the hammer moves in a first direction away from the anvil, and
wherein the compressible fluid applies a biasing force against the hammer in a second direction opposite to the first direction in response to the hammer reaching a maximum axial displacement from the anvil.
8 . The impact power tool of claim 7 , wherein the sealed region includes a seal plate positioned between the hammer and the gear assembly.
9 . The impact power tool of claim 8 , wherein the camshaft extends through the seal plate.
10 . The impact power tool of claim 8 , wherein a shape of the seal plate corresponds to a shape of an inner volume of the housing.
11 . The impact power tool of claim 8 , wherein the seal plate extends from the inner wall of the housing to an outer surface of the camshaft.
12 . The impact power tool of claim 7 , wherein the compressible fluid is air.
13 . An impact power tool comprising:
a housing;
a motor disposed within the housing;
a chamber within the housing containing a compressible fluid;
a gear assembly disposed within the housing, the gear assembly driven by an output of the motor;
an impact mechanism disposed within the housing, the impact mechanism driven by an output of the gear assembly, the impact assembly comprising:
a camshaft configured to rotate about a rotational axis;
an anvil rotatably supported by the housing, the anvil including a drive portion able to receive a tool bit, and
a hammer coupled to the camshaft, the hammer configured to rotate about the rotational axis and move axially along the camshaft to selectively apply rotational impacts to the anvil,
wherein the hammer is configured to compress the compressible fluid in the chamber as the hammer moves in a first direction away from the anvil,
wherein the compressible fluid applies a biasing force against the hammer in a second direction opposite to the first direction in response to the hammer reaching a maximum axial displacement from the anvil, and
wherein the impact mechanism does not include a mechanical spring such that the biasing force of the compressible fluid is the sole force acting to move the hammer in the second direction.
14 . The impact power tool of claim 13 , wherein the hammer includes an inner periphery adjacent the camshaft and an outer periphery adjacent an inner wall of the housing.
15 . The impact power tool of claim 14 , wherein the hammer includes a seal on the outer periphery of the hammer such that the seal contacts the inner wall of the housing.
16 . The impact power tool of claim 13 , wherein the chamber is fluidly sealed from atmospheric conditions at all positions of the hammer along the camshaft.
17 . The impact power tool of claim 13 , wherein the chamber includes a vent comprising a passage extending radially through a wall of the chamber,
wherein the hammer is configured to cover the vent, thereby sealing the chamber from atmospheric conditions, as the hammer moves in the first direction, and
wherein the hammer is configured to uncover the vent, thereby exposing the chamber to atmospheric conditions as the hammer moves in the second direction.
18 . The impact power tool of claim 13 , wherein the camshaft extends through the chamber.