US2995141A

US2995141A - Dual volume flow divider

Info

Publication number: US2995141A
Application number: US20904A
Authority: US
Inventors: William J Hipp
Original assignee: Webster Electric Co Inc
Current assignee: Webster Electric Co Inc
Priority date: 1960-04-08
Filing date: 1960-04-08
Publication date: 1961-08-08
Anticipated expiration: 1978-08-08
Also published as: GB925689A

Description

Aug. s, 1961 w. J. Hipp 2,995,141

DUAL VOLUME FLOW DIVIDER Filed April 8, 1960 /0 24 .v Im

/ IlIIII IllIIlI/I/ @aging INVENToR.

Arran/ey;

Unite The present invention relates generally to flow dividing valving for use in hydraulic systems and is more particularly concerned with a new and improved valve for use in hydraulic systems of the type required to supply fluid to different loads one of which must take priority `over the other.

While the valve of the present invention may Ibe used in a number of applications, one typical use may be on a Vehicle requiring hydraulic fluid for steering and also requiring fluid for performing auxiliary functions. For example, the hydraulic system used on lift trucks is usually called upon to supply iiuid for the steering control `and auxiliary fluid for operating the lift. In such systems, the steering control circuit must have priority over the auxiliary circuit so that the operator will not lose control of the vehicle in the event that the liuid supply is not capable of meeting the demands of both circuits. However, at all times when the iuid supply is more than adequate to satisfy the requirements of the steering circuit, it is desirable that all excess fluid be made available to the auxiliary or secondary circuit. Therefore, the primary object of the present invention is to provide new and improved valving meeting all of these requirements.

A further object of the invention is to provide valving of the character described which operates completely automatically to afford the desired priority for the primary circuit without requiring intervention by the operator.

Another object of the invention is to provide a valve of the type described above which is effective to permit diversion of a maximum amount of fluid to the auxiliary circuit whenever fluid is not required by the primary circuit.

The invention has for a further object the provision of valving of the type described for permit-ting a single hydraulic pump to serve both the primary circuit and the auxiliary circuit while at the same time assuring that fluid for the primary circuit will be available upon demand.

The foregoing and other objects are accomplished, in accordance with the present invention by providing valving for controlling the fluid iiow from a single pump to `a primary circuit and to an auxiliary or secondary circuit. The valving includes a iiow dividing valve for supplying a relatively small amount of fluid at all times to the primary circuit and for diverting all excess liuid to the secondary circuit. The latter valve includes a control element having a iiow restricting oriice therein producing a pressure drop or difference directly proportional to the rate of flow of fluid to the primary circuit. Whenever this pressure difference exceeds a predetermined value the piston is moved against a biasing spring to a position wherein it directs the major portion of the inlet iiuid to the secondary circuit independently of the oritice. A priority control valve is connected to the inlet to supply the major portion of the fluid to the primary circuit via a major iiow path in parallel with the path through the flow restricting orifice. The latter valve includes a piston normally biased by a spring to a position wherein it blocks the major flow path and prevents delivery of fluid via said path to the primary circuit. This piston is subjected to the pressure of the uid in the primary circuit acting in opposition to its biasing spring arent and, hence, when the latter circuit dem-ands more uid than can be supplied through the orifice in the iiow dividing valve control element the piston is moved to a position opening the major flow path. As soon as the demand of the primary circuit has been satisfied the priority control valve again becomes eifective automatically to block the major flow path, thus making available to the secondary circuit most of the fluid delivered by the pump. A pressure relief valve is provided for relieving any excess pressure of the fluid supplied to the primary circuit.

The invention, both as to its organization and manner of operation, together with further objects and advantages will best be understood by reference to the following description taken in conjunction with the accompanying drawing wherein:

FIG. l is a somewhat cross sectional view illustrating iiow dividing valving characterized by the features of the present invention although it should be understood that the view is not a true cross section since the passages in the valve body have been illustrated as though they lie in a single plane while, in actual practice, it is necessary lto offset these passages to establish the desired flow paths;

FIG. 2 is a fragmentary view somewhat similar to FIG. l but illustrating the priority valve in a position -wherein it is effective to deliver a major portion of the fluid from the inlet to the primary circuit; and

FIG. 3 is a fragmentary view illustrating "a modification of the valving shown in FIGS. l and 2.

Referring now to the drawing and first to FIG. l, the Valve of the present invention is there indicated generally by the reference numeral 9 and includes a valve body 10 having defined therein 1a main valve bore 11, a secondary valve bore 12 and a plurality of drillings forming flow passages to be described hereinafter. The main valve bore 11 contains a flow `dividing valve 13 for distributing to a primary circuit 14 and Va secondary circuit 15 inlet fluid supplied from a single hydraulic pump 16. The latter pump has its inlet connected to draw a suitable fluid such as oil from a tank or reservoir 17 and has its outlet connected through a pipe or conduit 18 to an inlet fitting 19 threaded into the valve body 10. The fitting `19 is connected to supply inlet liuid to the valve bore 11 through a passage 20 drilled into the valve body. The primary circuit 14, as was indicated previously, may comprise the steering control for a vehicle while the secondary circuit 15 may comprise equipment for performing auxiliary functions such las the lift on a power operated lift truck.

The iiow dividing valve 13 includes a piston 21 mounted for sliding movement within the valve 'bore 11 and biased upwardly as viewed in FIG. l by means of a coiled spring 22, the upward movement of the piston being limited by engagement of its end 21a with a plug 24 threaded into the valve body. The piston 21 is generally in the form of an open ended, hollow cylinder and cooperates with the bore 11 to define a spring chamber 23 containing the spring 22 which is seated at one end Iagainst the blind end of the bore 11 and at its other end is nested within the hollow 29 of the piston.

The piston 21 includes ya reduced diameter portion 25 bounded by lands 26 and 27 and cooperating with the valve bore 11 to define an inlet chamber 28 receiving liuid from the inlet passage 20. The inlet chamber 28 is connected continuously to the spring chamber 23 through one or more fiow restricting orifices 30 formed in the valve piston 21. These orifices provide a restricted flow path extending from the inlet passage 20 through the spring chamber 23 and around the extreme lower end 31 of the valve piston to an outlet passage 32 leading t0 the primary circuit 14. The passage 32 is drilled through the valve body 10 to intersect the valve bore 11 and includes a drilled portion 33 leading to a pressure relief valve 34 which will be described more fully hereinafter. An outlet fitting 3S threaded into the valve body 19 connects the passage 32 to a conduit or pipe 36 leading to the primary circuit.

The upper end of the piston 21 cooperates with the valve bore 11 to define a damping dashpot of conventional construction for inhibiting oscillation of the piston. More specically, the land 2'7 is provided with one or more passages 37 therein providing communication between the inlet chamber 28 and a dashpot chamber 32 formed within the valve bore 11 adjacent the upper end 21a of the piston. The high pressure duid in the inlet chamber 28 acts against the upper face 27a of the land 27 to develop a relatively large force urging the piston downwardly against the action of the biasing spring 22. It will also be understood that the fluid owing through the oriiices 30 is suicient to establish a pressure dilerence between the chambers 28 and 23. The force of the high pressure fluid acting against the upper end of the piston is opposed by the relatively low pressure fluid in the spring chamber 23, but when the rate of low through the oriices 30 increases suiciently to cause a pressure drop of predetermined value, the piston 21 is moved downwardly until the land 26 -unco'vers a passage 4@ leading to the secondary circuit 15. The latter passage is connected through a fitting 41 and through a conduit or pipe 42 to the secondary circuit. When the land 26 uncovers the passage 4G, the secondary circuit 15 is connected directly to the inlet chamber 28 and, hence, receives the major portion of the fluid from the pump 16, While the flow restriction orices 30 `limit the ow to the primary circuit to a very low level. The flow dividing valve 13 thus far described is of conventional construction and, hence, need not be considered in further detail.

In accordance with an important feature of the present invention, the major portion of the fluid for the primary circuit is supplied through a major flow path including a priority control valve 43 mounted within the secondary bore 12. The major ow path includes a passage 44 drilled through the valve body to intersect the inlet passage 20 and to connect with the bore 12. The drilling is made from the upper edge of the valve body and hence the extreme outer end is sealed by a plug 45. The major dow path further includes a passage 46 leading rom the bore 12 to a chamber 47 and a further passage 4S connecting the latter chamber t the spring chamber 23 in the valve bore 11. The chamber 47 is closed by a removable plug 49 threaded into the valve body which plug may be removed to permit insertion of a ow restricting element 59 in the form of a small plug having a small central orifice 51 therethrough. The latter plug may have an Allen socket 52 therein .for receiving a head of an Allen Wrench by means of which the plug may be threaded into or out of its seat in the valve body. The orifice 51 in the plug Sti provides a restriction in the major flow path leading from the inlet passage 2t) to the passage 32 for supplying uid to the primary circuit.

As was previously indicated, the uid ow through the major flow path just described is controlled by the priority valve 43 which includes a valve piston 54 mounted for sliding movement Within the secondary bore 12. The latter piston includes a pair of

lands

55 and 56 separated by a reduced diameter portion 57. A biasing spring 53 having one end seated in the blind end of the bore 12 and having its other end resting against the inner end of the piston urges the piston 54 to the right as viewed in FIG. l with the rightward movement being limited by engagement of an axially extending stem 59 on the piston with a plug 6h threaded into the outer end of the bore 12. The stern 59 cooperates with the bore 12, with the plug 60, and with the land 56 to define :a pressure chamber 61 which communicates with the primary circuit outlet passage 32 through a passage 62 in the valve body. When the pressure in the chamber 61 is at a relatively 10W value, the spring 58 is eiective to maintain the piston 54 at the right so that the land 55 covers the passage 44 in order to interrupt or block the major flow path. In the event that the primary or steering control circuit 14 is operated, the pressure of the uid in the passage 32 and in the chamber 61 builds 'up to a value suicient to move the piston 54 to the left against the biasing spring 53 to the position shown in FIG. 2 whereupon the passage 44 is connected to lthe passage 46 through the reduced diameter portion 57 thus opening the major tlow path. When the priority valve is opened uid is supplied in parallel with the dow through the orices 30 in order to meet increased demands of the primary circuit.

To prevent leakage uid entering the spring chamber at the blind end ofthe bore 12 from blocking the leftward movement of the piston 54, this spring chamber is connected through a passage 63 to the tank or reservoir 17. More specifically, the passage 63 opens to a chamber 64 containing the pressure relief valve34. The latter chamber is connected to the reservoir 17 through a drilled passage 65 in the valve body 11, through a bypass fitting 66, and through a pipe or conduit 67. The relief valve 34 is a conventional poppet type valve having a valve element 68 seated against a tapered valve seat 69 formed at one end of the chamber 64. The valve element 68 is biased into engagement with the valve seat by a spring 70 having one end encircling the stem on the valve element and having its other end telescoping over an inwardly extending projection 71 on a plug 72 threaded into the outer end of the chamber 64. A passage 73 connects the valve seat to the drilling 33 so that the valve element 68 is subjected to the pressure of the uid in the primary circuitA Thus when the latter pressure exceeds a predetermined val-ue, lthe valve element 68 is unseated to provide a bypass to the reservoir 17 through the chamber 64 and through the passage 65.

Considering next the operation of the valving shown in FIGS. l and 2 and assuming tirst the condition where the primary circuit 14 requires no fluid, it Will be observed that a very small amount of the fluid entering the inlet passage 20 is passed through the orifices 30 and through the passage 32 to the primary circuit. Under these conditions, the major portion of the inlet jfluid from the passage 20 is directed to the secondary circuit 15 through the passage 40. Since the primary or steering circuit 14 is not being operated at this time, the pressure of the uid 1n the passage 32 is very low and, hence, the valve piston 54 of the priority valve 43 is in the position shown in FIG. l wherein it blocks the major flow path. Thus, only the fluid passing through the oriices 3i? is supplied to the primary circuit or steering control.

. Assuming next that the operator has moved the steerlng control or primary circuit to steer the vehicle, it will be recognized that the pressure builds up in the passage 32. This pressure also exists in the chamber 61 and acts to move the piston 54 to the position shown in FIG. 2 against the spring 58 thus connecting the passages 44 and 46 and opening the major flow path. Fluid from the inlet passage 20 then ilows through the open priority valve 43 and through the orice 51 to the passage 32. Thus, the uild flowing through the oriiice 51 is in parallel with that owing through the orifices 30 and, as a result, an increased amont of uid is supplied through the passage 32 to the primary circuit 14. As long as the pressure of the uid in the passage 32 remains above the predetermined value determined by the spring 58, the increased tiuid flow through the major flow path will be available for the primary circuit. As soon as the demands of the latter circuit have been satisfied, the pressure of the Huid in the passage 32 and in the chamber 61 falls to a value where the spring S8 is again effective to move the piston 54 to the position shown in FIG. 1 thus again blocking or interrupting the major flow path. The duid that had been required for the primary circuit is thus made immediately available for the secondary circuit 15.

Any excess pressure of the fluid in the primary circuit passage 32 is relieved through the valve 34 in conventional manner.

Both the orifice 51 'and the orifices 30 are pressure compensated to insure constant fiow of uid regardless of changes in the inlet fiuid pressure. The amount of fluid fiowing through the major fiow path to the primary circuit passage 32 is controlled by the size of the orifice 51 and, hence, different rates of flow can be established by selection of ya plug 5f) having the proper orifice size. Preferably, the size `of the orifice 51 is such that the fluid fiow via the major fiow path is greater than that through the orifices 30 so that the major portion of the fluid required by the primary circuit is supplied by the priority valve.

The fiuid fiow through the major fiow path may also be controlled by the arrangement shown in FIG. 3 wherein the orifice size is adjusted 1from the exterior of the Valve body by turning a control element 80. The latter element includes a conically shaped inner end 81 forming a needle cooperating with the lower end of the passage 46 to form the variable orifice. The stem of the control element is threaded into a tapped axial bore 82 in the plug sealing the lower end of the chamber 47 to permit the adjustment. A lock nut 83 is preferably provided for the purpose of locking the control element 80 in position after it has been properly adjusted.

In view of the foregoing discussion, it will be observed that the Valving illustrated and described is effective to -accomplish all of the enumerated objects of the invention. Thus, this Valving provides priority for the fluid iiowing to the primary circuit and at the same time makes available for the secondary circuit a maximum amount of fiuid whenever the demands of the primary circuit are satisfied. All of this is accomplished automatically and Without intervention by the operator. Moreover, the mechanism required is very simple in construction employing a minimum number of compactly arranged parts.

While particular embodiments of the invention have been illustrated and described, it will be understood by those skilled in this art that many modifications and changes may be made without departing from the true spirit and scope of the invention as set forth in the appended claims.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. Valving for controlling the fiow of fiuid from a source to a primary circuit and to a secondary circuit, said Valving including valve body means having first and second valve bores defined therein, inlet passage means delivering inlet fiuid from the source to both of said bores, `a first valve piston mounted for reciprocation in said first bore and carrying means defining at least one ow restricting orifice, a chamber in said first bore receiving iiuid fiowing from the inlet passage means through said orifice, an outlet passage in said valve body means spaced `from the inlet passage means and leading from said chamber to the primary circuit, said chamber being connected at all times to the inlet passage means through the orifice in the first valve piston, a spring disposed at least partly within said chamber and acting against the first piston to bias it towards one end of the first valve bore, a secondary passage in said valve body means connected to said bore at a position intermediate the inlet passage means and the outlet passage and leading to the secondary circuit, the pressure drop across said orice caused by the flow of fiuid from the inlet passage means to the outlet passage through the orifice being effective to move said first piston within said bore against the action of said spring -whenever the rate of such flow exceeds a predetermined value, said first piston including means for connecting the inlet passage means to the secondary passage independently of the orifice when the first piston is moved a predetermined distance against said spring by the pressure drop across the orifice, a primary flow passage in said valve body means connecting said second bore to said chamber, a second valve piston mounted for sliding movement within said second bore, spring means in said second bore normally biasing said second piston to a position wherein it blocks flow of inlet iiuid from the inlet passage means to the primary flow passage, a passage in said valve body means connecting the outlet passage to the second bore in order to supply iiuid pressure acting against said second piston in opposition to said spring means so that increase in pressure of the fiuid in the outlet passage above a predetermined level causes said second piston to move within said second bore against said spring means, said second piston including means for connecting said inlet passage means to said primary flow passage when the second piston is moved against the spring means, thereby to deliver fiuid from the inlet passage means through the chamber to the outlet passage in parallel with the fiow through said orifice, and means in said primary flow passage for restricting the flow therethrough.

2. The apparatus defined by claim l wherein the flow restricting means in the primary flow passage comprises a plug detachably secured to the valve body means and having a fiow restricting orifice therein.

3. The apparatus defined by claim l wherein the fiow restricting means in lthe primary fiow passage comprises an adjustable valve element cooperating with a fixed Valve element to form an adjustable flow restricting orifice in the primary fiow passage, said adjustable element being adjustable from the exterior of Ithe valve body means to vary the size of the latter orifice.

4. Valving for controlling the flow of fluid from a source to a primary circuit and to a secondary circuit, said Valving including valve body means having first and second valve bores defined therein, inlet passage means delivering inlet fluid from the source to both of said bores, a first valve piston mounted for reciprocation in said first bore and carrying means defining at least one flow restricting orifice, an outlet passage in said valve body means spaced from the inlet passage means and leading from said chamber to the primary circuit, said outlet passage being connected to lthe inlet passage means through the orifice in the first valve piston, a spring acting `against the first piston to bias it towards one end of the first valve bore, a secondary passage in said valve body means opening to said bore at a position intermediate the inlet passage means and the outlet passage and connected to the secondary circuit, the pressure drop across said orifice caused by the flow of fluid from the inlet passage means to the outlet passage through the orifice being effective to move said first piston within said bore against the action of said spring whenever the rate of such flow exceeds a predetermined value, said first piston including means for connecting the inlet passage means to the secondary passage independently of the orifice when the first piston is moved a predetermined distance against said spring, a primary flow passage in said valve body means connecting said second bore to said outlet passage, a second valve piston mounted for sliding movement within said second bore, spring means in said second bore normally biasing said second piston to a position whenever it blocks fiow of inlet fiuid from the inlet passage means to the primary flow passage, a passage in said valve body means connecting the outlet passage to the second bore in order to supply fluid pressure acting against said second piston in opposition to said spring means so that increase in pressure of the fluid in the outlet passage above a predetermined level causes said second piston to move within said second bore against said spring means, said second piston including means for connecting said inlet passage means to said primary flow passage when the second piston is moved against the spring means, thereby to deliver fluid from the inlet passage means to the outlet passage in parallel with the flow through said orifice.

5. The valving defined by claim 4 wherein means are provided in said primary How passage for restricting the fluid flow therethrough.

6. The apparatus defined by claim 5 wherein the iiow restricting means in the primary fiow passage comprises an adjustable valve element cooperating with a fixed valve element to form an adjustable ow restricting orifice in the primary flow passage, said adjustable element being adjustable from the exterior of the valve body means to vary the size of the latter orifice.

7. The apparatus defined by claim 5 wherein the fiow restricting means in the primary fiow passage comprises a plug detachably secured to the valve body means and having a fiow restricting orifice therein.

8. Valving for controlling the ow of iiuid from a source to a primary circuit and to a secondary circuit, said valving including valve body means having first and second valve bores defined therein, inlet passage means delivering inlet fluid from the source toV both of said bores, a first valve piston mounted for reciprocation in said first bore and carrying means defining at least one fiow restricting orifice, an outlet passage in said valve body means spaced from the inlet passage means and leading from said chamber to the primary circuit,

said outlet passage being connected to the inlet passage means through the orifice in the first valve piston, a

spring acting against the first piston to bias it towardsy one end of the first valve bore, a secondary passage in said valve body means opening to said bore at a position intermediate the inlet passage means and the outlet passage yand connected to the secondary circuit, the pres-V sure drop across said orifice caused by the flow of fluid from the inlet passage means to the outlet passage through the orifice being effective to move said first piston within in said valve body means connecting said second bore to said outlet passage, and a priority valve element mounted for movement within said second bore and normally effective to prevent fiuid flow from the inlet passage means to the primary fiow passage, said valve element being movable in response to the pressure in said outlet passage to connect said inlet passage means to said primary flow passage.

9. The valving defined by claim 8 wherein means are provided in said primary fiow passage for restricting the fluid fiow therethrough.

10. The apparatus defined by claim 9 wherein the flow restricting means in the primary ow passage comprises a plug detachably secured to the valve body means and having a fiow restricting orifice therein.

11. The apparatus defined by claim 9 wherein the fiow restricting means in the primary flow passage comprises an adjustable valve element cooperating with a fixed valve element to form an adjustable flow restricting orifice in the primary fiow passage, said adjustable element being adjustable from the exterior of the valve body means to vary ythe size of the latter orifice.

l2. Valving for controlling the fiow of fiuid from a source to a primary load circuit and to a secondary load circuit, said valving comprising a fiow dividing valve receiving inlet fiuid from said source and constructed and arranged to continuously supply to said primary circuit a portion of the inlet liuid and automatically operated in response to the continuous iiow to divert to said secondary circuit inlet fluid not required by the primary circuit, and means for supplying fluid from the inlet Ito the primary circuit independently of the fiow dividing valve, the last named means including a priority valve having a movable valve element normally effective to prevent said ll ast named means from supplying fiuid to the primary circuit, said movable valve element being automatically moved from its normal position in response to an increase in pressure of the fluid delivered to the primary circuit from the fiow dividing valve to render the last named means effective kto supply inlet fluid to the primary circuit in parallel with the continuous fiow to the latter circuit through the flow dividing valve.

13. Valving for controlling the fiow of fiuid from a source to a primary circuit and to a secondary circuit, said valving comprising a flow dividing valve receiving inlet iiuid from said source and constructed and arranged to supply continuously to said primary circuit a portion l of the inlet fluid and operated in response to the continuous flow of fiuid to the primary circuit to divert to said secondary circuit inlet fluid not required by the primary circuit, and means for supplying fiuid from the inlet to the primary circuit independently of the fiow dividing valve, the last named means including a priority valve normally effective to prevent said llast named means from supplying fluid to the primary circuit and operated in response to pressure of the fluid delivered continuously to the primary circuit from the flow dividing valve to render the last named means effective to supply inlet fluid to the primary circuit in parallel with the continuous iiow through said iiow dividing valve.

References Cited in the file of this patent UNITED STATES PATENTS 501,959 Rawlings July 25, 1893 1,935,971 Wuesthoff Nov. 21, 1933 2,859,762 Banker Nov. 11, 1958