A method for acquiring unbalance amount of a rotor, comprises: manufacturing a rotor where the rotational journal of the rotor forms the rotation axis of the rotor; mounting the connecting part to the rotational journal of the rotor to form an assembly where the connecting part forms the rotation axis of the assembly, the connecting part and the rotor can be rotated with a relative angle, and the relative position between the rotation axis of the rotor and the rotation axis of the rotor assembly is kept unchanged before and after the rotor and the connecting part are relatively rotated with the certain angle.

A method for acquiring unbalance amount of a rotor, comprises: manufacturing a rotor where the rotational journal of the rotor forms the rotation axis of the rotor; mounting the connecting part to the rotational journal of the rotor to form an assembly where the connecting part forms the rotation axis of the assembly, the connecting part and the rotor can be rotated with a relative angle, and the relative position between the rotation axis of the rotor and the rotation axis of the rotor assembly is kept unchanged before and after the rotor and the connecting part are relatively rotated with the certain angle.

Systems and methods for reducing inertial forces of a reciprocating piston internal combustion engine are described. The systems and methods may provide for counterweights in a form of pistons in cylinders that are moved via electromagnets. The counterweights may be moved at a frequency that corresponds to engine speed via an alternating current.

An adjustable magnetic counterbalance assembly wherein a counterbalance force of the adjustable magnetic counterbalance is adjustable. The adjustable magnetic counterbalance assembly includes at least one ferromagnetic tube; a magnet disposed in the at least one ferromagnetic tube and configured to be axially movable and wherein the magnet is configured to be rotationally movable relative to the respective at least one ferromagnetic tube; wherein the counterbalance force is configured to be adjustable by adjusting the rotational position between the magnet and a respective ferromagnetic tube to change the polar alignment of the magnet. Alternatively, the adjustable magnetic counterbalance assembly changes the counterbalance force based on the relative alignment of the poles of one magnet to an adjacent one.

An adjustable magnetic counterbalance assembly wherein a counterbalance force of the adjustable magnetic counterbalance is adjustable. The adjustable magnetic counterbalance assembly includes at least one ferromagnetic tube; a magnet disposed in the at least one ferromagnetic tube and configured to be axially movable and wherein the magnet is configured to be rotationally movable relative to the respective at least one ferromagnetic tube; wherein the counterbalance force is configured to be adjustable by adjusting the rotational position between the magnet and a respective ferromagnetic tube to change the polar alignment of the magnet. Alternatively, the adjustable magnetic counterbalance assembly changes the counterbalance force based on the relative alignment of the poles of one magnet to an adjacent one.

A balance shaft structure includes a balance shaft including a balance weight, a driven gear to rotate the balance shaft by being engaged with a drive gear, a scissors mechanism, whose position in an axial direction is regulated, including a scissors gear to reduce backlash between the drive gear and the driven gear and an axially urging member to urge the scissors gear toward the driven gear in the axial direction, a first regulating portion to regulate an axially inner position of the scissors mechanism, and a second regulating portion fixed to the balance shaft on a side close to the shaft end part of the balance shaft beyond the first regulating portion and configured to regulate an axially outer position of the scissors mechanism.

A power-driven reciprocating tool may include a transmission mechanism that converts rotational force from a motor to linear force to be output by a reciprocating mechanism coupled thereto, and a counterbalancing mechanism coupled to the transmission mechanism to counter-balance forces generated by the reciprocating mechanism. The transmission mechanism may include a planetary gear assembly including a sun gear in meshed engagement with at least one planet gear. In response to a force converted by and transmitted from the transmission mechanism, the reciprocating mechanism may move in a first linear direction, and the counterbalancing mechanism may move in a second linear direction, opposite the first linear direction. The opposite linear movement of the reciprocating mechanism and the counterbalancing mechanism may counteract forces generated by the reciprocating motion of the reciprocating mechanism, thus reducing vibration output by the tool.

An electric power tool includes a drive device for providing a driving force, a rotation wheel that has a central axis and is driven by the drive device to rotate around the central axis, a spindle that supports a tool holder configured to hold a tool of the electric power tool, a first intermediate member, a second intermediate member, and a counterweight device. The first intermediate member is offset from the central axis of the rotation wheel, and revolves around the central axis when driven by the rotating rotation wheel, while driving the spindle to reciprocate in a first direction. The second intermediate member is driven by the first intermediate member to rotate around the central axis and is disposed to be offset from the central axis of the rotation wheel on the side opposite the first intermediate member. The counterweight device is driven by the second intermediate member.

An electric power tool includes a drive device for providing a driving force, a rotation wheel that has a central axis and is driven by the drive device to rotate around the central axis, a spindle that supports a tool holder configured to hold a tool of the electric power tool, a first intermediate member, a second intermediate member, and a counterweight device. The first intermediate member is offset from the central axis of the rotation wheel, and revolves around the central axis when driven by the rotating rotation wheel, while driving the spindle to reciprocate in a first direction. The second intermediate member is driven by the first intermediate member to rotate around the central axis and is disposed to be offset from the central axis of the rotation wheel on the side opposite the first intermediate member. The counterweight device is driven by the second intermediate member.

A crank and connecting rod mechanism which can realize Miller cycle and its control method, wherein an interior of a crankshaft is provided with a drive oil channel and a lock-up oil channel. A connecting rod neck of the crankshaft is arranged with an eccentric connecting rod bearing. In a crankshaft balance weight, a drive gear meshing with an outer meshing gear ring of the eccentric connecting rod bearing through an idle gear is installed. A planetary gear is installed in a drive gear hollow shaft. A lockpin is designed for the drive gear hollow shaft so as to lock with the crankshaft balance weight or with a planetary gear shaft.