device for converting a rotary motion into a linear oscillating motion at a constant speed and a hydraulic device therefor

摘要

A rotary motion/constant velocity linear reciprocating motion conversion device capable of converting rotary motion into a constant velocity linear motion or vice versa, and a hydraulic system which can minimize a ripple by using the above-mentioned conversion device, comprises a rotary motion part having a pair of first power transmission elements (4,5) rotating at the same speed mounted to a common shaft, each element having alternatively positioned teeth capable of transmitting power. A linear motion conversion part comprises a second pair of power transmission elements (6,7) each positioned adjacent to and engaging the teeth of the first elements. The second elements are each slidably mounted to a helical spline (9) and comprise projections (12,13) that engage helix grooves (10) arranged in opposite directions along the shaft. The interaction of first and second power elements causes the linear motion of the helix shaft. The helical spline comprises a piston at each end (25,26) that reciprocates within a respective cylinder (27,28). The first and second power elements and the helical spline is configured so that the pistons and cylinders effect the pumping of fluid in a manner minimizing hydraulic pressure pulsations.