Hydraulic motor

This application is a continuation of U.S. patent application Ser. No. 13/946,778, filed on Jul. 19, 2013, which claims the benefit of U.S. Provisional Patent Application No. 61/673,594, filed on Jul. 19, 2012. The contents of these applications are incorporated herein in their entirety.

This application relates to hydraulic motors generally and, in particular, to hydraulic motors having an adjustable limit of mechanical torque.

An improved hydraulic motor apparatus having an end cap and an adapter attached thereto is disclosed herein, as described in more detail below. A filter and valve may be located in the adapter to improve flexibility and performance. The motor apparatus can be mounted on a vehicle or other powered machine or apparatus. Also disclosed herein is a method for installing a combined insert and bushing for the motor swash thrust bearing into a motor housing, where the bushing acts to retain the components of the thrust bearing in the insert.

A better understanding of the objects, advantages, features, properties and relationships of the invention will be obtained from the following detailed description and accompanying drawings which set forth illustrative embodiments that are indicative of the various ways in which the principles of the invention may be employed.

FIG. 1 is a perspective view of a hydraulic motor apparatus in accordance with an embodiment of the present invention.

FIG. 2 is a perspective view of the motor apparatus of FIG. 1 with certain components removed for clarity.

FIG. 3 is a plan view of the motor apparatus of FIG. 1 .

FIG. 4 is a cross-sectional view of the motor apparatus of FIG. 3 along line 4 - 4 in FIG. 3 .

FIG. 5 is a cross-sectional view of the motor apparatus of FIG. 3 along line 5 - 5 in FIG. 3 .

FIG. 6 is a partial schematic, cross-sectional view of the motor apparatus of FIG. 3 along line 6 - 6 in FIG. 3 in combination with a hydraulic pump.

FIG. 7 is a schematic of the motor apparatus of FIG. 1 in combination with other system components.

The description that follows describes, illustrates and exemplifies one or more embodiments of the present invention in accordance with its principles. This description is not provided to limit the invention to the embodiment(s) described herein, but rather to explain and teach the principles of the invention in order to enable one of ordinary skill in the art to understand these principles and, with that understanding, be able to apply them to practice not only the embodiment(s) described herein, but also any other embodiment that may come to mind in accordance with these principles. The scope of the present invention is intended to cover all such embodiments that may fall within the scope of the appended claims, either literally or under the doctrine of equivalents.

It should be noted that in the description and drawings, like or substantially similar elements may be labeled with the same reference numerals. However, sometimes these elements may be labeled with differing numbers or serial numbers in cases where such labeling facilitates a more clear description. Additionally, the drawings set forth herein are not necessarily drawn to scale, and in some instances proportions may have been exaggerated to more clearly depict certain features. As stated above, the present specification is intended to be taken as a whole and interpreted in accordance with the principles of the present invention as taught herein and understood by one of ordinary skill in the art. It will be further understood that for clarity in certain cross-sectional views, certain elements are not shown in cross-section, as doing so would not assist in the understanding of the invention.

FIGS. 1-6 illustrate an embodiment of a hydraulic motor apparatus 110 including a motor housing 120 wherein a motor assembly 122 is coupled to and hydraulically drives an output shaft 125 . Motor housing 120 can be mounted on a frame (not shown) by fasteners such as screws 121 shown in FIG. 1 . Hydraulic motor apparatus 110 further includes a hydraulically ported end cap 130 and adapter 140 in communication with motor assembly 122 . As depicted, motor assembly 122 is a fixed displacement axial piston motor driven by hydraulic fluid supplied by a separate hydraulic pump 116 (shown schematically in FIG. 6 ). As will be understood by one of skill in the art, hydraulic pump 116 should be a unidirectional pump to avoid back-flushing filter 160 . Alternatively, a bidirectional pump (not shown) could be used to supply hydraulic fluid to hydraulic motor apparatus 110 in the event a filter bypass (not shown) is incorporated in adapter 140 . Motor assembly 122 includes pistons 124 which are set in motor cylinder block 123 and bear against thrust bearing 126 . An optional Hall effect sensor 155 can be included to act as a rotational sensor to detect the speed of rotation of the motor cylinder block 123 by sensing the pistons 124 as they rotate past sensor 155 . The speed of rotation of the motor cylinder block 123 , and hence that of output shaft 125 , is communicated back to a controller 170 in a feedback loop for controlled adjustment of a pressure reducing valve 150 , as detailed herein below and illustrated in FIG. 7 . Thrust bearing 126 is disposed in an insert 127 that has one or more (two shown) indentations 127 a . Indentations 127 a interface with mating protrusions 120 a of motor housing 120 to prevent rotation of insert 127 and to ensure proper orientation of thrust bearing 126 . Indentations 127 a can be shaped or sized differently from one another or located such that insert 127 can only be installed in one orientation to prevent an assembly error.

A bushing 128 retains the components of thrust bearing 126 in insert 127 . Insert 127 can be placed in a fixture to install the bushing 128 . Insert 127 has a fixture contact face 127 b that is parallel to a thrust bearing contact face 127 c . This allows bushing 128 to be press-fit into insert 127 , with pressure applied at a 90 degree angle to face 127 c , prior to installation of combined insert 127 and bushing 128 into motor housing 120 . Components of thrust bearing 126 can be located inside bushing 128 before the combined insert 127 and bushing 128 are installed in motor housing 120 . Alternatively, such components of thrust bearing 126 may be located inside bushing 128 after the combined insert 127 and bushing 128 are installed in motor housing 120 . The angle of thrust bearing contact face 127 c relative to the axis of rotation of output shaft 125 establishes the displacement angle of motor assembly 122 .

Rotation of motor cylinder block 123 drives output shaft 125 that extends through block 123 . Output shaft 125 is supported in motor housing 120 by bearings 114 and 115 and extends from an end of motor housing 120 opposite end cap 130 . Axial face seal 118 is press fit onto the output shaft 125 to deflect water spray and other contamination away from the shaft seal 113 , particularly water from high-pressure washing of vehicles, machines or equipment in which hydraulic motor apparatus 110 is used. The exposed end of output shaft 125 can be fitted with a fan blade assembly (not shown) or coupled to drive a wheel or other drivable mechanism (not shown).

End cap 130 is secured to motor housing 120 by screws 131 and provides flow of hydraulic fluid between motor assembly 122 and adapter 140 . End cap 130 and motor housing 120 cooperate to form an internal sump or chamber 112 . End cap 130 has a motor inlet port 130 a which connects to motor inlet passage 130 c to provide hydraulic fluid under pressure to motor assembly 122 . After passing through motor assembly 122 , hydraulic fluid then flows through motor outlet passage 130 d and motor outlet port 130 b . In the embodiment depicted, inlet port 130 a and outlet port 130 b are formed on a surface of end cap 130 generally perpendicular to the running surface 130 m on which motor cylinder block 123 is disposed. End cap 130 includes a flushing orifice 130 e that allows hydraulic fluid to pass from motor outlet passage 130 d into motor chamber 112 to ensure that motor chamber 112 is always sufficiently filled with clean, filtered hydraulic fluid. End cap 130 also includes a case drain passage 130 f which communicates with case drain port 130 g to allow excess hydraulic fluid to flow from motor chamber 112 to an external reservoir 162 , as depicted schematically in FIG. 7 . End cap 130 has system port tubes 130 h which define portions of motor inlet passage 130 c and motor outlet passage 130 d and carry fluid from and to adapter 140 . Optional system port tubes 130 i and 130 k (all shown closed/not machined) allow adaptation of the end cap 130 for use with an alternative embodiment (not shown) of adapter 140 or simply as system ports in an application where an adapter is not needed. Adapter 140 can be removed so that motor inlet port 130 a and motor outlet port 130 b serve as system ports connected in a known manner by hydraulic lines and fittings to a standalone pump, such as hydraulic pump 116 . Motor inlet port 130 a and motor outlet port 130 b are shown threaded to receive fittings in order to illustrate the versatility of hydraulic motor apparatus 110 , but threads are not required in these ports to install adapter 140 .

As shown in FIG. 5 , adapter 140 is secured to end cap 130 by screws 141 and provides an interface with both the pressure reducing valve (PRV) 150 and the filter 160 . Adapter 140 has motor inlet projection 140 j positioned within motor inlet port 130 a and motor outlet projection 140 k positioned within motor outlet port 130 b . Thus, adapter inlet passage 140 c communicates with motor inlet passage 130 c and adapter outlet passage 140 d communicates with motor outlet passage 130 d to provide a portion of the hydraulic fluid circuit.

As shown in FIGS. 6 and 7 , hydraulic fluid under pressure enters adapter 140 through system inlet port 140 a and passes into PRV inlet passage 140 e . PRV 150 is installed in PRV port 140 m and is in fluid communication with PRV inlet passage 140 e and PRV outlet passage 140 f . As depicted, PRV 150 is a normally-closed valve having a pressure relief function at a predetermined upper limit (P max ) that can also be electrically controlled to allow passage of hydraulic fluid therethrough across a range of pressures below P max in response to command signals from a controller 170 in communication with one or more system sensors 171 , 172 measuring system parameters affected by the output of hydraulic motor apparatus 110 . PRV 150 can be a screw-in, cartridge-style, pilot-operated, spool-type, electrohydraulic reduction valve that can be infinitely adjusted across a prescribed pressure range using a variable electrical input, such as the model PRV10-POC valve manufactured by Comatrol of Easley, S.C. As current supplied by controller 170 to PRV 150 increases, the pressure at which PRV 150 cracks to allow hydraulic fluid to pass from PRV inlet passage 140 e to PRV outlet passage 140 f decreases.

The use of PRV 150 establishes a maximum allowable system pressure (P max ) and sets a limit on the mechanical torque of output shaft 125 ; thus, protecting the components of motor assembly 122 . The ability of controller 170 to adjust the pressure at which PRV 150 cracks permits variable output from hydraulic motor apparatus 110 in response to system parameters being monitored by controller 170 . When the hydraulic fluid pressure in PRV inlet passage 140 e is below the set pressure limit, all of the hydraulic fluid under pressure entering through system inlet port 140 a passes through adapter inlet passage 140 c and flows through end cap 130 to motor assembly 122 . Fluid at lower pressure then flows back from motor assembly 122 through end cap 130 and into adapter outlet passage 140 d and from there into filter inlet passage 140 g . After passing through filter 160 , the hydraulic fluid passes through filter outlet passage 140 h and out through system outlet port 140 b . When the hydraulic fluid pressure in PRV inlet passage 140 e is above the set pressure limit, a portion of the hydraulic fluid entering through system inlet port 140 a flows from PRV inlet passage 140 e into PRV outlet passage 140 f through PRV 150 , thus bypassing motor assembly 122 . The bypass of that portion of the hydraulic fluid will be sufficient to reduce the hydraulic fluid pressure in PRV inlet passage 140 e and also adapter inlet passage 140 c to the set limit. It will be appreciated by one skilled in the art that limiting the hydraulic fluid pressure to motor assembly 122 will limit the mechanical torque of the output shaft 125 .

By way of example only, if hydraulic motor apparatus 110 is applied as a fan drive motor, wherein output shaft 125 is coupled to a fan (not shown) to cool the oil or coolant of an internal combustion engine (not shown), the measured system parameters registered by the one or more sensors 171 , 172 could be oil and/or coolant temperature. Fan speed, as measured by optional Hall effect sensor 155 , and the resultant volume of air pulled across the fins of a radiator (not shown) affect these system parameters. Controller 170 modulates fan speed to affect change in these system parameters by opening and closing PRV 150 as previously described. Feedback from sensor 155 provides a more granular control. In a closed position, the entire flow of hydraulic fluid received from a pump, such as pump 116 , through motor assembly 122 is uninterrupted and fan speed is maximized. When the sensors 171 , 172 indicate that oil and/or coolant temperatures are within predetermined control limits, controller 170 will open PRV 150 , permitting a portion of hydraulic fluid to bypass motor assembly 122 , reducing its output and consequently fan speed and system loads.

While one or more specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any equivalent thereof.