Transmission for a work machine with attached hydraulic fluid pump

A transmission assembly for a work machine (10) includes a transmission (16) having a transmission housing (18), a manifold housing (20) attached to the transmission housing (18), and hydraulic pump (22) configured to be connected to the manifold housing (20).

FIELD OF THE INVENTION

The present invention relates to work machines, and, more particularly, to transmissions used in such work machines.

BACKGROUND OF THE INVENTION

A work machine such as an agricultural tractor or a construction tractor may include an internal combustion (IC) engine which provides input power to a transmission, which in turn is coupled with and drives the rear axles through a rear end differential. The transmission, rear end differential and rear axles are sometimes referred to as the “rear end” of the work machine.

The tractors have hydraulic systems which include hydraulic pumps which supply pressurized hydraulic fluid to various hydraulically operated devices. These devices include a hitch system, selective control valves (SCV's) connected to hydraulic cylinders, steering, brakes, and a transmission which includes hydraulically controlled valves and a hydraulic lubrication circuit. The hitch system is located at the rear of the vehicle and the SCV are located at the middle and rear of the vehicle. Some of the hydraulic cylinders are used to operate implements connected to the rear of the vehicle.

These hydraulic pumps are typically in the form of gear pumps and are mounted to the engine which provides the power for the pumps. Typically the hydraulic systems include hydraulically operated devices that are a considerable distance from the pumps, requiring each system to be plumbed with a multitude of hoses, piping and fittings which are costly to produce, provide potential leak paths and consume valuable space on the tractor.

What is needed in the art is a tractor with a hydraulic system that is efficient, conserves tractor space and minimizes exposure of hydraulic components.

SUMMARY OF THE INVENTION

The invention in one form is directed to a manifold housing for a work machine. The manifold includes an external surface configured for connection to an external surface of a transmission and a plurality of internal passages. The manifold also includes a plurality of spaced apart ports, each of the plurality of spaced apart ports connected to at least one of the plurality of internal passages.

The invention in another form is directed to a work machine, including an engine and a rear end coupled with the engine. The rear end includes a transmission having a transmission housing, a manifold housing attached to the transmission housing, and a hydraulic pump. The hydraulic pump is configured to be connected to the manifold housing.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention and referring now toFIG. 1, a work machine10is shown. The work machine10includes an engine12(shown in simplified block form) and a rear end14(partially shown) coupled to the engine12. The work machine10may be, for example, in the form of an agricultural tractor or a construction vehicle. The rear end14includes a transmission16having a transmission housing18. The rear end also includes a manifold housing20attached to the transmission housing18and a hydraulic pump22connected to the manifold housing20.

As shown inFIG. 1, the work machine10further includes a filter cartridge24. The filter cartridge24is used to filter hydraulic fluid that may become contaminated in the hydraulic fluid systems of the work machine10. The manifold housing20, as shown inFIG. 1, includes an external surface26for receiving the filter cartridge24. The filter cartridge24includes a housing that cooperates with the external surface26of the manifold housing to contain hydraulic fluid therein. The filter cartridge24with this configuration does not require a separate filter cap to access the filter within the cartridge. The hydraulic pump22of the work machine10is an internal hydraulic pump. The internal hydraulic pump22is positioned in the manifold housing20.

The hydraulic pump22may supply pressurized hydraulic fluid to various hydraulic operated devices (not shown) such as a brake system, a transmission, a steering system, a hitch system such as a three-point hitch for an agricultural tractor, and selective control valves (SCVs) connected to hydraulic cylinders. The work machine10further includes a second hydraulic pump in the form of a proximal hydraulic pump28connected to the manifold housing20at external surface30of manifold housing20. The work machine10further includes a third hydraulic pump in the form of a distal hydraulic pump32attached to the proximal external hydraulic pump28. The proximal hydraulic pump28and the distal hydraulic pump32may be any type of hydraulic pump and may for example be a vane or a gear pump. Typically, the proximal hydraulic pump28and the distal hydraulic pump32are gear pumps.

Referring now toFIG. 2, the manifold housing20includes a plurality of internal passages34and a plurality of spaced apart external ports36. Each of the plurality of spaced apart external ports36is connected to at least one of the plurality of internal passages34. The passages34and ports36serve to direct the flow of hydraulic fluid to and from the pumps22,28and32and to and from the filter cartridge24. For example, and as shown inFIG. 2, the manifold housing20includes a first internal passage38extending from SCV return port40to filter inlet port42. The manifold housing also includes a second internal passage44extending from filter outlet port46to internal pump outlet port48.

As shown inFIG. 2, the internal hydraulic pump22is in the form of a gear pump and is located within second internal passage44of manifold housing20. The internal hydraulic pump22is driven from the transmission16. The transmission16includes an input gear50which drives output gear52. The output gear52rotates along longitudinal axis54. As shown inFIG. 2, the internal hydraulic pump22includes an input or drive gear56as well as a driven gear58. The internal passage44serves as a reservoir to contain hydraulic fluid that also serves as direct lubrication of a bearing59that supports the drive gear56of the internal hydraulic pump22. A similar bearing (not shown) may support the driven gear58of the internal hydraulic pump22and may be similarly lubricated. The hydraulic pump input gear56therefore rotates about longitudinal axis54of the output gear52of transmission16. The use of the internal hydraulic pump22provides a hydraulic pump that minimizes space in the rear end14, as well as, a pump that is located closer to the need for hydraulic power, for example, the transmission16.

Further, and as is shown inFIG. 2, the internal hydraulic pump22also serves to transfer power from the transmission16to the proximal hydraulic pump28. The drive gear56of the internal hydraulic pump22includes an internal spline60that mates with input shaft62of the proximal hydraulic pump28. The input shaft62, thus, also rotates about longitudinal axis54of the output gear52of the transmission16. As such, the internal hydraulic pump as serves as the coupler between the shaft on the output gear52of transmission16and the input shaft62of the proximal hydraulic pump28. The dual use of the internal pump22as a pump and as a coupler saves space and cost.

As shown inFIG. 2, the rear end14further includes the third pump or distal external pump32. The distal external pump32is mounted to proximal external pump28. The proximal hydraulic pump28includes an internal spline68that mates with an external spline70on input shaft72of the distal pump68. The distal external pump32and the proximal external pump28may be used to provide pressurized hydraulic fluid to one or more of the hydraulic operated devices such as the brake system, the transmission, the steering system, the hitch system, and the SCVs. Since at least the hitch system, and the SCVs are rearwardly located on the tractor, the position of the pumps28and32in a more rearward location than prior pumps that are mounted to the engine, results in a tractor with fewer and shorter hydraulic hoses and piping and fewer hydraulic fittings.

Referring now toFIGS. 3,4and5, the pump drive gear56and the pump driven gear58are shown positioned in internal passage44of the manifold housing20to form internal hydraulic pump22. The internal hydraulic pump22is connected to proximal hydraulic pump28by internal passages which, in turn is connected to distal hydraulic pump32by internal passages. The hydraulic pumps22,28and32thus use a common inlet. The common inlet of the three hydraulic pumps22,28and32provides the pumps to be hydraulically interconnected. The three hydraulic pumps22,28and32utilize a common suction consisting of the internal passages and, therefore, do not require external plumbing to provide suction. No external suction plumbing on the three hydraulic pumps22,28and32reduces parts and opportunity for leaks, as well as, saves space and cost. As such all the hydraulic pumps22,28and32help each other concerning priming of the pumps. The common inlet permits all the hydraulic pumps22,28and32to be connected to a common sump88. Further, the fluid in these pumps22,28and32may be filtered by the same filter, namely filter cartridge24. This pump configuration is also very compact, using less tractor space and fewer and simple components than previous designs.

Referring again toFIG. 2, the filter cartridge24is shown in greater detail. As shown inFIG. 2the filter cartridge24includes a housing78which defines internal threads80for mating with external threads82formed on the manifold housing20. The filter cartridge24further includes a return filter element84and a suction filter element85. Hydraulic fluid for the three pumps22,28and32is supplied through filter cartridge24from sump port86of sump88within the transmission16. The hydraulic fluid from the sump88passes through sump port86, into passage89between inner wall90of filter cartridge24and return filter element84, through return filter element84, through port46, and into second internal passage44of the manifold housing20.

Returned hydraulic fluid from implement hydraulic cylinders and the like passes from SCV return port40, through internal passage38, to filter inlet port42, through return filter element84of filter cartridge24, through filter outlet port46, and to second internal passage44of the manifold housing20. The SCV return port40is positioned on the readily accessible exterior of the manifold housing20. Similarly, ports on the proximal hydraulic pump28and the distal hydraulic pump32are positioned on the readily accessible exterior of the pumps28and32. The location of the SCV return port40and the ports of pumps28and32provides geometry that avoids complicated hydraulic fittings including ninety degree bend fittings and “T” connectors that may be necessary with prior art engine mounting of hydraulic pumps. Hydraulic fluid for the three pumps22,28and32is thus supplied from the sump88and from the SCV return port40. The filter cartridge24filters both fluid to the pumps22,28and32supplied from the SCV return port40and fluid to the pumps22,28and32supplied from the sump88.

The filter cartridge24is mounted on the manifold housing20and the manifold housing20is mounted on the transmission16. The manifold housing20includes the sump port86for fluid communication with sump88within the transmission16. When the transmission16is not operating, the fluid within will drain through sump port86to sump88within the transmission housing18. The filter cartridge24is so positioned relative to the transmission16, the manifold housing20, and the sump88such that, when the transmission is not operating, at least most of the hydraulic fluid within the filter cartridge24will flow from the filter cartridge24through the manifold housing20to the sump88, so that the filter cartridge24may be removed and replaced, cleanly and efficiently.

Referring now toFIGS. 2,5,6and7, the ports and passage that provide paths for the fluid from the manifold housing20, the filter cartridge24, and the sump88are shown in greater detail. When the engine12of the work machine10is not running, the transmission16is not rotating and the pumps22,28and32are not turning. When the pumps22,28and32are not turning, the fluid is not longer pressurized and the fluid drains by gravity. The filter cartridge24is positioned horizontally, permitting fluid within the cartridge24to drain into the manifold housing20. Fluid within the manifold housing may drain into the sump88. The drain from the pumps22,28and32to the manifold housing20and from the cartridge24to the manifold housing20have a flow generally the reverse of the flow described above while the pumps22,28and32are turning. The filter cartridge24drains when the pumps are not turning and may then be removed and replaced.