ULTRASONIC HYDRAULIC BOOSTER PUMP AND BRAKING SYSTEM

摘要

An ultrasonic pump (10, 10', 210) having a first housing (12, 212) connected to a second housing (74) to create a cavity (14) therebetween. The first housing (12, 212) has a central stem (20) that extends into the cavity (14) with a passage (21, 22) for connecting the cavity (14) with an outlet port (26). The second housing (74) has an inlet port (82) for communicating hydraulic fluid to the cavity (14). A plurality of piezoelectric discs (40) are located on the stem (20) by a first diaphragm (42, 242) to define an actuation chamber (54, 254) within the cavity (14). The first diaphragm (42, 242) engages the first housing (12, 212) and stem (20) for isolating the piezoelectric discs (40) from hydraulic fluid supplied to the cavity (14) and place a predetermined axial force on the piezoelectric discs (40). A second diaphragm (54) located in the first (12, 212) and second (74) housing has first (58) and second (60) surfaces which are substantially equal distances from the passage (21, 22) and the inlet port (82). Thereafter, air is bled from cavity (14) to assure that only hydraulic fluid is present in the cavity (14). The piezoelectric discs (40) are connected to a source of electrical energy (200) and in response to an excitation signal develop a fluctuating force. The fluctuating force has an axial component and a radial component and the axial component alone is communicated to the first diaphragm (42, 242). After the axial component of the fluctuating force overcomes the predetermined axial force, the fluid pressure of the hydraulic fluid in the cavity (14) changes as a function of the axial component force. This change in fluid pressure causes sequentially movement of first (58) and second (60) surface of the second diaphragm (54) toward the inlet port (82) and passage (21, 22) and as a result hydraulic fluid is transmitted from the cavity (14) through the passage (21, 22) to the outlet port (26).