US2940260A

US2940260A - Fluid system

Info

Publication number: US2940260A
Application number: US727669A
Authority: US
Inventors: Lyle L Mylcraine
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-04-10
Filing date: 1958-04-10
Publication date: 1960-06-14
Anticipated expiration: 1977-06-14

Description

FLUID SYSTEM Lyle L. Mylex-aine, Piper City, ll.

Filed Apr. 10, 1958, Sel'. No. 727,669

2 Claims. (Cl. Gil- 52) This invention relates to a self-contained pressure dfferentiating and uid metering device. It is described hereafter in connection with a hydraulic system of a farm tractor, in which it has particular practical application, but it is to be understood that the dev-ice has numerous other applications.

Modern farm tractors are customarily equipped with hydraulically operated draw bars. The hydraulic systems by which the draw bars are operated frequently are provided with pumps of such character as to circulate a large amount of hydraulic iluid at a relatively low pressure, for example ten to fourteen gallons per minute at thirty to twelve hundred pounds per square inch. Such a system has a number of advantages but it also has a serious disadvantage in that it cannot satisfactorily be used to operate other hydraulic equipment, such as a hydraulically operated power steering system, because such other equipment frequently operates at a dilferent pressure. For this reason, it has been customary to install a separate and independent hydraulic system for the power steering at considerable expense, rwith a separate pump capable of delivering a relatively small amount of duid at a relatively high pressure.

One of the objects of this invention is to provide a simple, compact device whereby a part of the energy of iiuid which is moving under a head is utilized to pump a portion of the same fluid at a pressure different from the head under which the iluid was moving.

Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawing.

In accordance with this invention generally stated, a device is provided in which uid moving under pressure is directed against vanes the effective area of which is selectively variable, in such a way that the vanes are caused to move and at the same time the eiective area of some of the vanes is decreased. A portion of the uid initially directed against the vanes is in turn impelled by the vanes with diminished area.

vIn the drawing, lFigure l is a sectional View taken along the line 1-1 of Figure 2, showing a device constructed in accordance with one embodiment of this invention in a hydraulic system of a tractor, the hydraulic system being shown diagrammatically; and

lFigure 2 is a sectional view taken along the line 2-2 of Figure 1.

Referring now to the drawing for an illustrative embodiment of this invention, reference numeral 1 represents a hydraulic system for a farm tractor, including a pump 2, a draw bar raising mechanism with the usual control valve and bypass arrangement, all indicated diagrammatically at 3 in Figure l, a pressure pipe 4 leading from the discharge side of the pump 2 and a return pipe 5 connected, by way of the draw bar raising mechanism 3, to the suction side of the pump 2.

In the hydraulic system 1, connected to the pressure pipe 4 at one side and to the return pipe 5 at the other, ,is a pressure diierentiating and duid metering device nited States Patent 0 constructed in accordance with one embodiment of this invention. The device 10 comprises a casing 12 and a rotor 50. The casing 12 is made up of a block 13 and a cover plate 14 bolted to the block 13 by means of studs 15'. The studs 15 take into tapped holes 16 in the block I3, passing through holes 17 in the cover plate 14. The block 13 is provided with an inlet passage 19, tapped to take a threaded end of the pressure pipe 4, and an outlet passage 20, tapped to take a threaded end of the return pipe 5. Intermediate the inlet passage 19 and outlet passage 20 is a -rotor cavity 22. The rotor cavity 22 is made up of a circular inner journal cavity 23, a circular outer journal cavity 24, and a vane receiving channel 25. The vane receiving channel 25 lies between the

journal cavities

23 and 24. It'communicates with the inlet passage 19 and the outlet passage 20, between which it is substantially concentric with the

jonrnal cavities

23 and 24. It also connects the outlet passage 20 with a discharge passage 26. The discharge passage 26 has

branches

27 and 28. A discharge pipe 30 is screwed into a threaded section of the discharge passage 26. Between the outlet passage 20 and the branch 27, the vane receiving channel 25 is also concentric with respect to the

journal cavities

23 and 24. Between the edge of the branch passage 27 nearest the outlet passage 20 and the edge of the branch passage 28 farthest from the outlet passage 20, the radial depth of the channel 25 decreases until at the edge of the branch passage 28 most remote from the outlet passage 20, the radii of the channel 25 and the

journal cavities

23 and 24 are identical, as shown in Figure 1. In the quadrant between the branch passage 28 and the inlet passage 19, the radius of the channel 25 remains the same. A passage 36 in the block 13 communicates with the inlet passage 19 and with the center of the inner journal cavity 23.

The rotor 50 is disc-shaped and is proportioned rotatably to fit within the

journal cavities

23 and 24. In the embodiment shown, it is provided with eight radial slots or recesses 51 in each of which a vane 52 is slideably mounted. Each vane 52 is biased outwardlyV by a spring 53 seated at one end in `a bore 54 in the bottom of the slot 51, and at the other end in a recess 55 in the vane 52. An axial passage 5S in the rotor 50 communicates at one end with the passage 36 and at its other end with branch passages 59 each connected with the bottom of a bore 54.

The vane receiving channel 25 is wide enough closely to receive the vanes 52 of the rotor 5G. It is wider than the

passages

19 and 20 along the area of communication with those passages as shown in Figure 2. The radial depth of the channel 25 with respect to the

journal cavities

23 and 24 and the rotor 50, between the inlet passage 19 and the outlet passage 29, is less than the length of the vanes 52 between their outside edges and the bottom of the recesses 55 against which the springs 54 bear. 'Ihe radial depth of the channel 25 between the outlet passage 20 and the branch passage 27 of the discharge passage '26 is less than the radial depth of the channel 25 between the inlet passage 19 and the outlet passage 20, so that the volume of liuid :which can be accommodated by the channel 25 between successive vanes is less between the outlet passage 20 and the branch passage 27 than it is between the inlet passage 19 and the outlet passage 20.

In the embodiment shown, the discharge pipe 39 is connected with a power steering apparatus 35, indicated diagrammatically in Figure l, from which the fluid ilows through a differential Valve 37, also shown somewhat diagrammatically in Figure 1. The differential valve shown utilizes the bias of a spring 38 to maintain a greater pressure in the power steering system 35 than exists in the draw bar system. A steering system return pipe '39 connects the differential valve 37 with the return pipe i In the operation of the illustrative embodiment shown, the system isilled with hydraulic uid, generally an oily liquid.V When the-pump 2 is started, the `viiuid `isforced through 'the pressure'pipeV 4. The `uid moves through thel inlet passage 19 and, acting upon Yaffvaneg52 begins to rotate the-rotor 50.` A small part ofV the fluid iwill -pass-V through the passages 36 andSSlinto` the-branch passages-59, hence to the inside ofthe-recesses or slots 51 where it will tend to force the vanes 52-outwardly, assisting the springs 53. As the rotor, 50 begins; to turn,

and the iiuid in the system begins `to circulate, most 'of 1` the fluid' passingY through the channel 25 between fthe inlet passage 19and the outlet ,passagey 20 -will bedischarged into the outlet passage 20,Y hence tvo-,the return pipe 5. A part ofthe uid, however, will be-forced into the channel 25 between the outlet-passage 20 and creases, so'that the iiuid` between the vanes is forced through the branch passage 27 and,` when the leading vane has begun to pass the branch passage 28, through the branch passage 28 into the discharge passage 26.

The pressure which is producedin the line 30, is dependent upon the differential valve 38, so long as the product of the pressure and the volume of fluid through the power steering system is less than the product of the pressure and the volume of fluid flowing through the channel 25 between the inlet passage 19 and the outlet passage 20, less the power losses due to friction of the rotor, line loss and the like. In the drawing of the illus trative embodiment shown, the radial depth of the channel 25 between the inlet passage 19 and the outlet passage 20 is about three times that of the channel between the outlet passage 2G and the branchy27. If the various losses to which reference has been made were disregarded the device should be capable of producing a pressure at the discharge passage 26 of slightly less than three times the pressure in the inlet passage 19, i.e., the pressure at Vwhich the uid is delivered from the pump 2. In practice, in order to ensure free circulation of the fluid, a multiplication of one and one-half to two times is considered reasonable.

In practice, both the draw -bar system and the power steering system will be provided with a reservoir of uid under pressure. Y

The advantages of the device of this invention ywill be immediately apparent to tractor owners. With the aid of this simple device, the ordinary low pressure pump, which has ample capacity to handle both systems, can be utilized for Vboth the draw bar operating system and a powerV steering system, at a small fraction of the cost of the installation of a totally separate power steering system and pump.

As a specific example of a device of this invention used with a hydraulic system on an ordinary farm tractor,

Y in which a pump delivers ten to fourteen gallons per minute of hydraulicV fluid at thirty to twelve hundred pounds per square inch pressure, the overall size of the block and cover plate can be six by six by two and onehalf'inches. The inlet passage 19 may have-a bore of approximately seven-eighths of aniinch, T he rotor 50 i may be approximately four inches in diameter and two inches wide, and the slots 51 approximately one and threequarters of an inch deep. The vanes 52vmay be approximately one and one-half inches long and approximately one and three-quarters toY two inches wide; The channel 25 between the inlet passage 19and the outlet passage 20 may beV approximately one-half of anginchk deep 4and approximately one and three-quarters to two inches wide. The depth of the channel 25 between the outlet passage 20 and the branch passage 21 may be approximately threeeighths of an inch deep. The bore of the outlet passage 20-may be approximately seven-eighths of Ian inch, and of the discharge passage 26, one-half of an inch. A pressure of thirty to twelve hundred poundsV perrsquare inch may b e producedV by the `differential valve 37, although, when the control valves Yto the drawbar raising cylinder and the powermsteering cylinders, not here shown, are in neutral position,the pressure regulatorA (by-pass) valves ofthe `steering and drawbar raising mechanisms are normally arranged toropen and allow ythe pump to circulate iuid at low pressure.

The bore of the outlet passage 20 can either be made smaller than the bore of the inlet passage 19 or a suitable choke can be used so that the combined volumes of the fluid delivered to the discharge vpassage 26'and the outlet passage 20 is the same as the volume of uid delivered to the inlet passaget19. This ensures that the channel 25 betweenV the outlet passage 2 0 and the discharge passage 2,6 isvm'aintained full.

In the device described, the hydraulic uid itself acts to lubricate the 'Various parts. While the rotor fits closely withinrthe rotorcavity, there isY still enough clearance, for example from .Q01 to .0005 inch, between the at faces ofthe rotor disc and the -iiat face dening the bottom of the inner journal cavity 23 onthe one side and the cover plate providing the bottom of the outer ljournal cavity 24 onY the other, and between the peripheral surfaces of the rotor and journal cavities, to permit some of the iiuid to get between them to accomplish the lubrication. Y v t `When liquids which have little or no lubricating qualities are to be handled, it may be-necessary to mount the rotor on a Ishaft journaledV in conventional sealed bearings which may be of any of'numerous suitable kinds known to the art. The block, cover plate and rotor may be complementarily grooved toY form races to receive ball bearings, or the rotor may be provided with stub shafts on either side,journaled in bearing cavities in the block and cover plate. It can be seen that the `device of this invention has numerous applications beyond the hydraulic system of a tractor. Itcan be used not only asa pressure differentiator but as a metering or proportionating device. If the channel 25 is` kept filled, a volume of fluid bearing the same relationship to the total volume as the depth of the channel 25 between the outlet passage 20 and the discharge passage 26 bears to the depth of the channel 25 between the'inlet passage 19 and the outlet passage 20 will be delivered to the discharge passage 26. Thus, water, oil, or other liquids which are pumpedthrough a pipe under pressure, or gas, can be metered olf by the use of this device. Y Y

Numerous variations in the construction of the device of this invention, within lthe scope of the appended'claims will occur to those skilled in the art in the light of the foregoing disclosure. For example, the effective surface area of the vanes may be varied in ways other than making them slide radially within the slots in the rotor. If

the vanes are made of rubber or other resilient material, they need not slide in radial slots in the rotor, but can be iixed on the periphery of the rotor. This arrangement is particularly useful in adevice akin to the hydraulic ram. l VYHaving thus described the invention, what is claimed K and desired to be securedby Letters Patent is:

`caribe utilized to operate the power steering` apparatus,

comprising a casing having a rotor cavity, an inlet passage to said rotor cavity connected to the discharge side of the pump, an outlet passage to said rotor cavity connected, by way of the drawbar mechanism, to the suction side of said pump and a discharge passage connected to the power steering system; a rotor rotatably mounted within said cavity, a plurality of vanes mounted in said rotor for radial sliding movement and extending closely but slideably within a channel in said cavity, said channel extending in an arc substantially concentric with the rotor between the inlet passage and the outlet passage and between the outlet passage andthe discharge passage, said channel connecting said passages respectively, the depth of said channel between the outlet passage and the discharge passage being substantially less than the depth of the channel between the inlet and outlet passages and the depth of the channel between the discharge passage and the inlet passage being substantially less than the depth of the channel between the outlet and discharge passages.

2. In a system wherein fluid ows in a conduit connecting a high pressure area to a low pressure area, a device of the character described, wherein the kinetic energy of the owing uid is utilized to multiply the pressure of a portion of the fluid itself, said device consisting of a casing having a rotor cavity deiined by a wall, an inlet passage communicating with said uid conduit on the high pressure side and with said rotor cavity, an

outlet passage communicating with said uid conduit on the low pressure side and with said rotor cavity, and a discharge passage communicating with said rotor cavity, said outlet passage lying between the discharge vand inlet passages; a rotor rotatably mounted within said rotor cavity, and vanes mounted on said rotor, said vanes being biased to bear against the wall defining the rotor cavity and adapted to move in response to variations in the contours of said wall, said wall being substantially concentric with the rotor between the inlet passage and the outlet passage, and between the outlet passage and the discharge passage and defining a channel with said rotor, the cross sectional area of the channel between the inlet and outlet passages being greater than that between the outlet and discharge passages, and said rotor and wall defining a constricted section between the discharge passage and the inlet passage of less cross sectional area than that of the channel between the outlet passage and the discharge passage.

References Cited in the file of this patent UNITED STATES PATENTS 1,296,356 Bey Mar. 4, 1919 2,832,199 Adams et al Apr. 29, 1958 FOREIGN PATENTS 892,075 France J an. 3, 1944