Battery-powered percussive massage device
A percussive massage device includes an enclosure having a cylindrical bore that extends along a longitudinal axis. A motor has a rotatable shaft that rotates about a central axis perpendicular to the longitudinal axis. A crank coupled to the shaft includes a pivot, which is offset from the central axis of the shaft. A transfer bracket has a first end portion coupled to the pivot of the crank. A flexible transfer linkage has a first end coupled to a second end portion of the transfer bracket. A piston has a first end coupled to a second end of the transfer linkage. The piston is constrained to move within a cylinder along the longitudinal axis of the cylindrical bore. An applicator head has a first end coupled to a second end of the piston and has a second end exposed outside the cylindrical bore for application to a person receiving treatment.
1. A percussive massage device comprising:
an enclosure having a cylindrical bore, the cylindrical bore extending along a longitudinal axis;
a motor positioned within the enclosure, the motor having a rotatable shaft, the shaft having a central axis, the central axis of the shaft perpendicular to the longitudinal axis of the cylindrical bore;
a crank coupled to the shaft, the crank including a pivot, the pivot offset from the central axis of the shaft;
a transfer bracket having a first end portion and a second end portion, the first end portion pivotally coupled to the pivot of the crank;
a reciprocation linkage having a first end and a second end, the first end of the reciprocation linkage fixedly coupled to the second end portion of the transfer bracket to move with the transfer bracket, the reciprocation linkage including a flexible portion between the first end and the second end, wherein:
the first end of the reciprocation linkage has a first profile has a first cross-sectional area;
the second end of the reciprocation linkage has a second profile having second cross-sectional area; and
the flexible portion of the reciprocation linkage has a varying profile having a varying cross-sectional area, the flexible portion having the first cross-sectional area near the first end, the flexible portion having the second cross-sectional area near the second end, the flexible portion having a cross-sectional area that decreases from the first cross-sectional area near the first end to a minimum cross-sectional area in a middle portion of the flexible portion and that increases from the minimum cross-sectional area to the second cross-sectional area;
a piston having a first end and a second end, the first end of the piston fixedly coupled to the second end of the reciprocation linkage, the piston positioned within the cylindrical bore of the enclosure and constrained to move only along the longitudinal axis of the cylindrical bore; and
an applicator head having a first end and a second end, the first end of the applicator head coupled to the second end of the piston, the second end of the applicator head exposed outside the cylindrical bore.
2. The percussive massage device as defined in claim 1 , wherein:
the pivot of the crank is rotatable 360 degrees about the central axis of the shaft of the motor, the pivot being aligned with the longitudinal axis of the cylindrical bore at a first rotational position and at a second rotational position, the first and second rotational positions spaced apart angularly by 180 degrees, the pivot offset from the longitudinal axis in a first offset direction when the pivot is at a rotational position between the first rotational position and the second rotational position in a first angular direction with respect to the first rotational position, the pivot offset from the longitudinal axis in a second offset direction when the pivot is at a rotational position between the first rotational position and the second rotational position in a second angular direction opposite the first angular direction;
the flexible portion of the reciprocation linkage is straight and is aligned with the longitudinal axis of the cylindrical bore when the pivot of the crank is aligned with the longitudinal axis of the central bore at the first rotational position or at the second rotational position;
the flexible portion of the reciprocation linkage bends in a first direction with respect to the longitudinal axis of the cylindrical bore when the pivot of the crank is offset from the longitudinal axis in the first offset direction; and
the flexible portion of the reciprocation linkage bends in a second direction with respect to the longitudinal axis of the cylindrical bore when the pivot of the crank is offset from the longitudinal axis in the second offset direction.
3. The percussive massage device of claim 1 , wherein the applicator head is removably coupled to the piston.
4. The percussive massage device of claim 1 , wherein the flexible portion of the reciprocation linkage comprises resilient rubber.
5. The percussive massage device of claim 4 wherein the resilient rubber has a Shore durometer hardness of approximately 50.
6. A method of operating a percussive massage device comprising:
rotating a shaft of an electric motor to rotate a pivot of a crank about a centerline of the shaft;
fixedly coupling the pivot of the crank to a first end of a reciprocation linkage of a reciprocation assembly, the reciprocation linkage having a second end and having a flexible portion between the first end and the second end, wherein:
the first end of the reciprocation linkage has a first profile having a first cross-sectional area;
the second end of the reciprocation linkage has a second profile having second cross-sectional area; and
the flexible portion of the reciprocation linkage has a varying profile having a varying cross-sectional area, the flexible portion having the first cross-sectional area near the first end, the flexible portion having the second cross-sectional area near the second end, the flexible portion having a cross-sectional area that decreases from the first cross-sectional area near the first end to a minimum cross-sectional area in a middle portion of the flexible portion and that increases from the minimum cross-sectional area to the second cross-sectional area;
fixedly coupling the second end of the reciprocation linkage to a piston constrained to move along a longitudinal centerline; and
coupling the piston to an applicator head wherein rotational movement of the pivot of the crank causes reciprocating longitudinal movement of the piston and the applicator head.
7. The method of claim 6 , wherein the applicator head is removably coupled to the piston.
8. The method of claim 6 , wherein the reciprocation linkage comprises resilient rubber.
9. The method of claim 8 , wherein the resilient rubber has a Shore durometer hardness of approximately 50.
10. A method of assembling a percussive massage device comprising:
attaching an eccentric crank to the shaft of a motor, the eccentric crank having a pivot;
coupling a first portion of a bearing holder to the pivot of the eccentric crank;
fixedly attaching a first end of a reciprocation linkage to a second portion of the bearing holder, the reciprocation linkage including a second end and a flexible portion between the first end and the second wherein:
the first end of the reciprocation linkage has a first profile having a first cross-sectional area;
the second end of the reciprocation linkage has a second profile having second cross-sectional area; and
the flexible portion of the reciprocation linkage has a varying profile having a varying cross-sectional area, the flexible portion having the first cross-sectional area near the first end, the flexible portion having the second cross-sectional area near the second end, the flexible portion having a cross-sectional area that decreases from the first cross-sectional area near the first end to a minimum cross-sectional area in a middle portion of the flexible portion and that increases from the minimum cross-sectional area to the second cross-sectional area;
fixedly attaching the second end of the reciprocation linkage to a first end of a piston, the piston constrained to longitudinal movement within a cylinder; and
removably attaching an applicator head to a second end of the piston.
11. The method of claim 10 , wherein the reciprocation linkage comprises resilient rubber.
12. The method of claim 11 , wherein the resilient rubber has a Shore durometer hardness of approximately 50.