Yuken Vane Pumps
These pumps intake and discharge fluid according to the change of space enclosed by the vanes and the cam ring that rotates by means of the rotor. Vane pumps in a low/middle pressure range from approximately 7 to 25 MPa (1 015 to 3 626 psi) and with middle displacement; for example, the single middle-pressure type has a displacement of approximately 300 cm3/rev (18.3 cu.in./rev). These pumps provide the following advantages: (1) minimized discharge pressure pulsation; (2) compactness and light weight for high output; (3) less efficiency degradation due to vane wear, and; (4) reliability and ease of maintenance.
The pumps are quieter because of the structure and are less susceptible to working fluid contamination than piston pumps. Therefore, they are conveniently used in a wide range of applications. The pumps typically have a structure where the vane is pressed against the cam ring by inducing pressurized flow to the bottom of the vane. With the improved structure, pumps capable of operating at a high pressure of up to 42 MPa (6 092 psi) are also commercially available.
Vane pumps are categorized into fixed and variable displacement types. Each type is further subcategorized into single and multiple pumps. With vane pumps, it is easy to construct double and triple pumps by mounting pump elements (components such as rotors, vanes, and cam rings) in tandem to the pump shaft. Such multiple pumps with displacements of 300 to 500 cm3/rev (18.3 to 30.5 cu.in./rev) have been commercialized.
Variable displacement type vane pumps, with changing ring eccentricity, are also available. These pumps, with displacements of 30 cm3/rev (1.83 cu.in./rev) or less, are widely used as hydraulic pressure sources for small machine tools.
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