Wear-resistant port plate for a fluid transfer device and fluid transfer device including same

Abstract

In a fluid transfer device (10) that includes a housing (12), a rotor (16) rotatably mounted in the housing (12) and having a bore (24) and at least one piston (30) slidingly mounted in the bore (24), a port plate (42) that includes a body portion (44) mountable in the housing (12) and formed from a first material and a wear layer (56) formed of a second material, different from the first material, attached to the body portion (44) and adapted to contact the rotor (16). Also a fluid transfer device (10) including such a port plate (42).

Description

FIELD OF THE INVENTION [0001] The present invention is directed to a port plate having a wear layer formed from a wear resistant material and a body portion formed from a second material and to a fluid transfer device including such a port plate, and, more specifically, toward a port plate having a ceramic or cermet wear layer connected to a metallic body portion and to a fluid transfer device including such a port plate. BACKGROUND OF THE INVENTION [0002] Fluid transfer devices are known that can be operated in a first direction as a pump and in a second direction as a motor. These devices may comprise a housing within which a rotor rotates with respect to a port plate and a cam plate angled with respect to the rotor's axis of rotation. The rotor includes a bore or bores for receiving one or more (generally an odd number) of pistons. One end of each piston is held against to the cam plate. As the rotor rotates with respect to the housing, each piston moves axially with respect to t...

AI Technical Summary

Problems solved by technology

However, it may be difficult to dynamically control the position of a rotor in such a device.

This can lead to excessive drag between the rotor and port plate at low pressures and to excessive leakage at higher pressures.

However, these port plates, with their various openings for accommodating balance pistons and flow channels for carrying fluids to and from the port plate, are more complex than the port plates used with floating rotor devices.

Significant wear occurs at the interface of the rotor and the port plate.

However, ceramics and cermets are generally more expensive than metals.

Using solid ceramic or cermet port plates increases the cost of fluid transfer devices.

In addition, these materials are more brittle than metals and can be difficult to machine.

Thus the formation of blind openings for fluid inlets and outlets, internal fluid passageways, and openings for accommodating balance pistons becomes difficult.

And, because port plates are often exposed to significant pressures during use, ceramic port plates, lacking the strength of metal port plates, may be more likely to crack during use.

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