Vibration and temperature variation of the cam ring of a hydraulic vane pump associated with vane tip detachment

Abstract

IntroductionHydraulic pumps and motors are transformers between mechanical energy and pressure, which are the key components of fluid power systems (JHPS, 1989). The pumps and motors are positive-displacement machines, which roughly classified into three groups: vane-, piston-, and gear-types. The reliability and efficiency of the equipment are greatly dependent on the tribological behaviors of the sliding parts (Yamaguchi, 1986), particularly under severe operating conditions. Hydraulic vane pumps are widely used in industry (ASTM, 2008) and can be broadly categorized into constant-volume and variable-volume pumps, as well as balanced-pressure and unbalanced-pressure pumps. The vanes are inserted into the slots of the rotor and the tips of the vanes slide on the inner surface of the cam ring as the rotor moves. The output of the pumps can be changed by altering the geometry of the displacement chambers, which consist of vanes, a cam ring, side-plates, and a rotor. Each chamber has bearing and sealing parts between the vane-tips and the cam ring-surface, between the vane side surfaces and the side-plates, and between the vane surfaces and the rotor slots.These bearing and sealing parts, especially those between the vane tips and the cam ring, should be under an appropriate load in order to maintain the seal, and a number of mechanisms, such as single vanes, dual vanes, intra-vanes, and spring-loaded vanes, have been proposed in order to satisfy this requirement. Under a specific condition, especially in the case of single-vane pumps, the tip of the vane could detach from the inner surface of the cam ring because the forces became unbalanced, due potentially to, e.g., excessive pre-compression of the pump chamber at the entrapment, a decrease in the back pressure on the vanes, and a reduction in the centrifugal force of the vanes at low rotational speed. The tip subsequently and immediately reattaches to the cam ring. Thus, violent and repeated detachment and reattachment occur, which reduces the efficiency and durability of the pump and leads to the 1 Vibration and temperature variation of the cam ring of a hydraulic vane pump associated with vane tip detachmentToshiharu KAZAMA* *Muroran Institute of Technology 27-1, Mizumoto-cho, Muroran, Hokkaido, 050-8585, Japan E-mail: kazama@mmm.muroran-it.ac.jp Received 28 June 2016 AbstractThe vibration acceleration and temperature changes of the sliding parts of a vane-type hydraulic pump were measured simultaneously, including under the operating condition in which vane tips became detached. The test pump was a compact vane pump with 12 vanes having a theoretical displacement of 9.4 ml/rev, a maximum discharge pressure of 21 MPa, and a maximum rotational speed of 30 s -1 . The vanes were inserted front to back into the slots of the pump rotor in order to allow ease of detachment. An acceleration pickup was affixed to the cam ring. In addition, four thermocouples were embedded in the cam ring, and four thermocouples were embedded in the side-plate. A hydraulic oil with I...