Bidirectional pump system having plural lubrication circuits

[57] ABSTRACT

A bidirectional pump circulates fluid through a common filter to two lubrication circuits individually having a sump, an inlet line to the pump, a system to be lubricated, and a return path to the sump. A checktype shuttle valve causes fluid to be discharged through either of two outlet paths according to the direction of pump rotation by way of a filter and thence to the two circuits. Alternatively, a dual check valve is provided in place of the shuttle valve.

Claims, 2 Drawing Figures

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PATENTEDDEC311974

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OU

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BIDIRECTIONAL PUMP SYSTEM HAVING PLURAL LUBRICATION CIRCUITS

BACKGROUND OF THE INVENTION

The present invention is directed to liquid pump systems. In particular, the invention is directed to plural lubrication systems having bidirectional pumps.

Various forms of machinery, such as earthmoving vehicles or the like, frequently require multiple lubrication systems, and it has been the practice to provide separate pumps, sumps, filters, and associated circuitry to match the flow requirements of the individual systems. This has proved to be expensive since duplicate components are not only provided, but also must be independently serviced.

With the simple adoption of a common lubricating fluid, a single pump could be used to draw fluid from two sumps, for example; and reference is made to U.S. Pat. No. 3,420,180 to Behrends, et al, assigned to the assignee of the present invention, showing such a system. However, an accompanying problem with many of these lubricating circuits that evolves because of economical considerations is that unidirectional pumps are adapted thereto which are ineffective in one direction of rotation, notwithstanding the fact that they are driven by reversible mechanisms. Consequently, the fluid flow to such lubricating circuits is terminated for the duration of the time that the pumps are being driven in reverse. An example of such a unidirectional pump system adapted specifically to the final drive of a track-type tractor is set forth in application Ser. No. 327,093, filed Jan. 26, 1973.

SUMMARY OF THE INVENTION

Accordingly, it is an object of this invention to provide a bidirectional pumping system for distributing fluids to plural lubricating circuits.

It is a further object of this invention to provide a bidirectional pump system which will distribute lubricant fluid to plural lubricating systems in either direction of pump rotation.

It is a further object to provide such a pumping system using a single pump to feed two lubricant systems and thus save material and cost.

It is a still further object to provide a bidirectional pump system having proportional distribution and selfbalancing capability.

The invention takes the form of a system having a bidirectional pump for pumping fluid from a pair of spaced-apart sumps and thence through a shuttle-type check valve, and a pair of circuits including lubricant systems before returning to sump. The check valve serves to direct fluid to the lubricant systems in either pump flow direction. A pair of spaced-apart sumps ensures self-balancing if the flow requirements of each circuit are unequal and/or one pump inlet line is not fully immersed in fluid because of the tilting of the vehicle or associated machinery. Fluid distribution is continued to both circuits from the other of the pump inlet lines, thus provides self-balancing of the fluid levels in the two circuits. Flow control orifices in the circuits provide for proportional flow to each lubricant system.

Other objects and advantages will be apparent to one skilled in the art from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall schematic diagram illustrating the features of the present invention.

' FIG. 2 is a view of an alternate embodiment of the check valve of the system of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT &gt;0 With reference to FIG. 1, there is illustrated generally a dual lubrication system 10 incorporating a bidirectional, gear-type pump 12, a filter 14, and first and second horizontally spaced-apart sumps 16 and 18 at the same vertical level, respectively. The pump in⁵ eludes a pair of intermeshing gears 20 and 22 which are driven by a reversible mechanism such as associated with a final drive of a conventional vehicle (not shown). When these gears are driven in the clockwise and counterclockwise directions as shown by the solidand broken-line arrows, respectively, they draw fluid upwardly from the first and second sumps through a first inlet conduit 24 to a first cavity 26, and a second inlet conduit 28 into a second pump cavity 30. Fluid from the first and second cavities is drawn centrally inwardly and upwardly with rotation of the gears, as shown by the solid arrows, to a first chamber 32 and thence to a first discharge or outlet conduit 34. Conversely, if the gears 20 and 22 are respectively driven ₃₀ in the counterclockwise and clockwise directions shown by the broken arrows, fluid in the cavities 26 and 30 is pumped to a second chamber 36 and to a second discharge or outlet conduit 38.

The first and second discharge conduits 34 and 38 35 are disposed on opposite ends of and communicate with a shuttle-type check valve 40. A filter inlet passage 42 medially communicates valve 40 with filter 14. With rotation of the gears in the direction of the solid arrows and consequent pressurization of the first discharge 40 conduit 34, a ball 44 is urged rightwardly against a seat 46 to block flow of pressurized lubricant to the conduit 38 and allow free travel thereof to the filter inlet passage. When the pump is driven in reverse in the direction of the broken arrows and the second discharge line 45 38 is pressurized, the ball 44 is moved leftwardly against the seat 48 to block the pressurized fluid from the conduit 34. Thus, in either direction of rotation of the gear pump 12, fluid flows through the filter inlet passage 42, the filter 14, a filter outlet passage 50, and ⁵⁰ to a first branch conduit 52 and a second branch conduit 54.

The divided flow of fluid in the branch conduits 52 and 54 is proportioned by a first flow control orifice 56 associated with a first lubrication system 58, and a sec- ond flow control orifice 60 associated with a second lubrication system 62. While fluid from the first lubrication system 58 is delivered to the first sump 16 through a schematically represented first return path or conduit ₆₀ 64, fluid from the second lubricant system 62 is delivered to the second sump 18 through a similar second return path or conduit 66. Thus, a first lubrication circuit shown generally by the reference numeral 68 is defined by the sump 16, inlet conduit 24, pump 12, filter ₆₅ 14, branch conduit 52, flow control orifice 56, lubrication system 58, and return conduit 64. A second lubrication circuit 70 is similarly defined by the sump 18, inlet conduit 28, pump 12, filter 14, branch conduit 54,

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4 flow control orifice 60, lubrication system 62, and return conduit 66.

In the event that an inlet port 72 or the first inlet conduit 24 or an inlet port 74 of the second inlet conduit 28 is uncovered from the fluid contained in the sumps 5 16 and 18, respectively, due to disproportionate flow distribution such as may occur due to tilting of the vehicle or associated mechanism containing the subject dual lubrication circuits, the opposite inlet port 74 or 72 will still serve to distribute fluid to both the lubrica- 10 tion circuits 68 and 70. The flow-proportioning control orifices 56 and 60 will proportionately distribute the fluid from the pump 12 and, entering one of the intake conduits 24 or 28 to both sumps 16 and 18, the system will be self-balancing. 15

Turning to FIG. 2, a dual check valve system 76 may be alternately used in place of the shuttle-type check valve 40 in FIG. 1. In this alternate embodiment, a first check valve 78 is opened and a second check valve 80 is closed when outlet conduit 34 is pressurized allowing 20 flow of fluid to filter inlet passage 42, while blocking the evacuated conduit 38. In reverse operation of the gear pump 12 and with pressurization of the outlet conduit 38, the second check valve 80 is opened and the first check valve 78 is closed, allowing fluid passage to 25 the inlet passage 42 in a manner substantially similar to that of the preferred embodiment. Springs 82, 84 normally bias balls 86, 88, against seats 90, 92, respectively.

It is to be understood that the foregoing description 30 is merely illustrative of preferred embodiments of the invention and that the scope of the invention is not to be limited thereto, but is to be determined by the scope of the appended claims.