WO2019114915A1 - Use of ball bearings in positive displacement hydraulic pumps and motors with geometric volume controlled by control fluid volume - Google Patents

Abstract

The invention relates to positive displacement hydraulic pumps and motors with geometric volume controlled by control fluid volume that comprise cams. Each cam drives a set of followers, in the case of a pump, or the followers drive the cam, in the case of a motor. The followers form a closed barrier that surrounds the cam completely, separating the inner chamber containing the cam from a chamber formed outside the followers. Function as a motor or pump, and the operations required therefor, is based on controlling the fluid and the volume and flow thereof into and out of the inner and outer chambers. The sliding movement between the parts, and the resulting friction, is a problem that reduces the efficiency and expected lifespan of same. In the present invention, to prevent the sliding movement between the parts, and the resulting friction, and to restrict pure rolling, the cam and the followers make contact only by means of ball bearings. This occurs in one of two ways. Either one ball bearing is secured to each follower such that the follower is connected to the cam by means of the outer race of the ball bearing, or the cam is formed from the same number of ball bearings as followers such that the cam is connected to each follower by means of the outer race of the ball bearing positioned opposite the follower at that moment. The connection of the ball bearing to the followers is exchanged by means of the rotation of the cam. This sequence facilitates the design of the function of the displacement, speed and acceleration of the follower, linked to the angle of rotation of the cam. If the ball bearing is secured to the follower, the formation of the movement depends on the formation of the cam surface. When the cam is formed by the set of ball bearings, the formation of the movement depends on the formation of the follower surface.