US3465519A

US3465519A - Hydraulic flow controlling apparatus

Info

Publication number: US3465519A
Application number: US661657A
Authority: US
Inventors: John C Mcalvay; Glenn R Hubbard
Original assignee: Webster Electric Co Inc
Current assignee: Webster Electric Co Inc
Priority date: 1967-08-18
Filing date: 1967-08-18
Publication date: 1969-09-09
Anticipated expiration: 1986-09-09
Also published as: GB1240192A; DE1751934A1; DE1751934B2

Description

P 1969 J. c. MCALVAY ETAL 3,

HYDRAULIC FLOW CONTROLLING APPARATUS Filed Aug. 18, 196'? 2 Sheets-Sheet 1 lNVENTORS JOHN C. McALVAY GLENN R HUBBARD By WW, WWW,

Aflys.

Sept. 9, 1969 c, MCALVAY ETAL 3,465,519

HYDRAULIC FLOW CONTROLLING APPARATUS Filed Aug. 18, 1967 2 Sheets-Sheet 2 LEFT OUTRIGGER CROWD 24 RIGHT BUCKET OUTRIGGER /lflo l i I46 FIG. 2

' INVENTORSI JOHN C. MCALVAY GLENN R. HUBBARD United States Patent 3,465,519 HYDRAULIC FLOW CONTROLLING APPARATUS John C. McAlvay and Glenn R. Hubbard, Racine, Wis., assignors to Webster Electric Company, Inc., Racine, Wis., a corporation of Delaware Filed Aug. 18, 1967, Ser. No. 661,657 Int. Cl. Fb 15/02, 11/22; F16k 11/07 US. C]. 60-52 19 Claims ABSTRACT OF THE DISCLOSURE A double acting hydraulic cylinder is controlled by a four way spool valve, and the spool when moved from the idle position controls an adjustable restricted orifice through which fluid flows to the cylinder. A pressure operated priority flow divider valve is controlled by the pressure drop across the orifice to supply the cylinder with a metered, constant flow, the magnitude of which is determined by the manual setting of the spool valve. A metered excess flow is provided for supplying additional apparatus. Several of the valve constructions are connected in cascade to control several fluid motors in priority relation and independently of one another. Excess flow from the system regulates the pump displacement in accordance with system demand, and the pump displacement is also reduced in the event system pressure exceeds a predetermined value.

The present invention relates to hydraulic flow controlling apparatus and more particularly to improved valve apparatus and control systems for controlling the flow of pressurized fluid to hydraulic motors or the like.

In the control of a hydraulic motor such as a hydraulic cylinder or the like it is customary to provide a manually operated control or directional valve to control the flow from a fluid pump to the motor. In the idle or nonoperating condition of the valve, the valve blocks flow to the motor, and when operation of the motor is desired the valve is opened. Often it is desirable to operate the motor at a speed lower than that resulting when the entire flow from the pump is applied to the motor. The operator may attempt to produce such low speed operation by partially opening, or cracking, the control valve thereby to throttle the flow to the motor. Accurate speed control is difficult to obtain by this method, even by a skilled operator, because for a given valve opening the flow rate to the motor is affected by fluid pressure within the motor, the speed at which the pump is operating, and other factors. Thus in the usual system there is no consistent correlation between the position of the control valve and the rate of fluid flow to the motor.

In order to overcome this problem it has been suggested that a priority type flow splitter or divider valve be associated with a directional control valve in such a manner that a single manual operation serves to control the flow to the motor and also to establish a metered, constant flow rate for the motor. This objective has not been satisfactorily accomplished, and known constructions are generally unsatisfactory because they are slow to respond to manual adjustment, and they involve substantial pressure losses in addition to that imposed by the load. Furthermore,'in known structures, the excess flow over and above the priority flow requirement must be returned to tank at low pressure and thus cannot be used to supply other motors. In addition they are expensive to make and cumbersome to operate.

In view of these difiiculties, among the important objects of the present invention are to provide an improved valve construction for controlling the operation of a hydraulic motor; to provide a valve construction with which an operator may operate a motor easily and accurately at very low speeds; to provide an improved valve construction for controlling the application of pressurized fluid to the motor and for simultaneously establishing a metered rate of fluid flow to the motor; to provide a valve construction capable of accurately and conveniently controlling both the direction of operation of a motor and the speed of operation of the motor; to provide a motor controlling valve construction characterized by immediate response to manual adjustments; and to provide an improved valve construction of inexpensive and simple structure.

Many hydraulic circuits are designed for serving several hydraulic motors from a single pump. Customarily such circuits include a directional or control valve for each motor, and each of the control valves is supplied with fluid from the pump. The inlets of the valves may be arranged in series or parallel configurations and the valves may be either of the open-center or the closedcenter type. In known arrangements of the series type, the operating pressures of all of the motors are added together so that a large load is imposed upon the pump, and in addition such arrangements are not suitable for single acting cylinders and for some types of rotary motors. In parallel circuit arrangements, when two or more motors are operated simultaneously a lightly loaded circuit is served before a more heavily loaded circuit receives fluid. In addition, parallel circuits using closedcenter or blocking valves are subject to the difiiculty that the pump must operate continuously at the maximum output pressure, resulting in power losses, heating and pump wear.

Because of difliculties with various known types of single pump circuits, the modern tendency is to use two or more pumps to supply plural motors. However such arrangements are expensive, space consuming, and otherwise unsatisfactory. Thus it would be desirable to provide an improved circuit for supplying several motors from a single pump while avoiding the disadvantages associated with the usual series in parallel arrangements.

Accordingly, important objects of the present invention are to provide an improved hydraulic circuit for serving several motors from a single pump wherein each motor can be operated at a selected speed independent of the load condition of the other motors; wherein selected motors are served on a priority basis in the event of inadequate pump flow, wherein the entire pump flow is made available to downstream motors when the higher priority motors are not operated; wherein there is no interaction between branches; and wherein the pressure loss in the idle condition is minimized.

A further object of the invention is to provide a hydraulic circuit for serving one or more fluid motors wherein the pump flow is controlled in accordance with the system demand and wherein the pump pressure is only slightly higher than the highest pressure demanded in the system at any time.

In brief, the above and other objects and advantages of the present invention are achieved in one embodiment of the invention by a valve construction including a manually operated valve member for controlling the application of fluid from a pump to a motor. In the idle position of the valve member, the flow to the motor is blocked, and when the valve member is moved to an operating position fluid is permitted to flow to the motor. A pressure operated priority flow divider valve receives the pump flow and provides a priority flow which is available to the motor by way of the main valve, and also provides an excess flow when the priority demand requirement is satisfied. An adjustable orifice associated with and controlled by movement of the manually operated valve member establishes the priority flow requirement so that a metered flow of any selected rate is made available to the motor by a single manual operation. The excess flow may be used to supply other hydraulic equipment, and there is no interaction between the branches regardless of their respective pressures.

In order to supply several motors, two or more of the valve constructions may be'connected in cascade with the excess flow from the first valve construction being supplied to the inlet of the second, and so on. With this arrangement, the pump flow is divided into a metered priority flow supplied to the first motor and a first excess flow. The first excess flow is divided into a second priority flow supplied to a second motor and a second excess flow, and so forth. Each of the flow dividers is adjustable so that the priority flow requirement of its corresponding motor may be established at any selected level. Accordingly, the entire flow to any one valve construction is available to the downstream valve constructions when the one valve is in its idle position. In addition, when two or more motors are being operated simultaneously, there is no interaction between the branches, each being isolated by its associated priority fiow divider.

In accordance with another feature of the invention, the excess flow from the final valve construction of a cascaded system, or the excess flow from a single valve it only one motor is included in the system, may automatically be maintained at a constant low rate by varying the displacement of the fluid pump. In this manner the pump flow is always only slightly higher than the total flow requirement. Also, pump displacement may be reduced in the event system pressure exceeds a predetermined value.

Other objects and advantages of the invention will appear from the following description of an illustrative embodiment of the invention, in the course of which reference is had to the accompanying drawings, in which:

FIG. 1 is a sectional view of a valve construction embodying the features of the present invention, the valve construction being shown together with a hydraulic circuit illustrated schemaitcally; and

FIG. 2 is a largely schematic illustration of a hydraulic circuit for controlling an industrial tractor backhoe attachment and incorporating several of the valve constructions of FIG. 1.

Referring now to FIG. 1 of the drawing, there is illustrated a hydraulic circuit generally designated as including a fixed displacement fluid pump 12 which may for example be driven at varying speeds by the engine of a motor vehicle (not shown). The pump 12 pressurizes fluid received from a tank or reservoir 14 and supplies the pressurized fluid to a motor 16 by way of a control valve construction generally designated as 18 and embodying the features of the present invention. The motor 16 is illustrated as a double acting hydraulic cylinder and may be used, for example, to control an implement associated with the vehicle. In accordance with an important feature of the present invention, the valve construction 18 serves to control the direction of operation of the motor 16 and also controls the speed of operation independently of the size of the load to which the motor 16 is subjected and independently of the pump speed, both in response to a single manual operation.

In general, the valve construction 18 includes a priority flow divider or flow splitter generally indicated as 20 for dividing flow from the pump 12 into a constant rate priority flow supplied to the motor, and an excess flow which exists only when the priority flow requirement is satisfied. In addition, the control valve construction 18 includes a spool 22 whose position is controlled by a manual operating handle 24. Movement of the spool 22 serves to control the application of pressurized fluid to the motor 16 and also to establish the priority flow requirement automatically maintained by the priority flow divider 20, thereby to control the speed of operation of the motor 16.

, assembly in held in place by a cap plate 36 fastened to the end of the valve body 26, and the operating handle 24 is pivotally related to the body by means of a pivot pin 38 journalled in an car on the cap plate 36.

A second bore 40 in the body 26 slidably receives a flow dividing plunger 42. The system 10 is illustrated in the position assumed when the pump 12 is not operating, and the plunger 42 is held against a plug member 44 by means of a loading spring 46 held in compression between the end of the bore 40 and the plunger 42. The plug 44 is held in place by means of a snap ring 48 received in a groove in the body 26. When the pump 12 is operating, the plunger 42 is moved to the right from the position illustrated in FIG. 1 to open a power beyond outlet 62, as explained below.

As long as the spool 22 remains in its illustrated idle position, the entire flow supplied by the pump 12 will pass through the valve body and be expelled from the valve body through an excess flow or power beyond" outlet 62. In this position of the valve member, no fluid is supplied to the motor 16 and the motor 16 is not operated.

More specifically, assuming now that the pump 12 is operated to supply pressurized fluid, fluid enters the valve body 26 by way of an inlet port 50 and travels through an inlet passageway 52 to an inlet chamber 54 comprising an annular recess communicating with the valve bore 28. Pressurized fluid from the chamber 54 travels along a passageway 56 to an annular chamber 58 communicating with the valve bore 40. This fluid entering the valve bore 40 through the chamber 58 forces the plunger 42 against the spring 46 to the right from the position illustrated in FIG. 1. A land 42a on the plunger 42 seals against the wall of bore 40 and prevents communication between the chamber 58 and an excess flow chamber 60 spaced along the valve bore from the chamber 58 in the absence of inlet pressure. However, when the plunger 42 is moved to the right by pressure fluid supplied from the pump, communication is established between the chambers 58 and 60, and fluid'flows from the chamber 60 through the power beyond outlet 62. Fluid outlet 62 may be returned to tank, or, as will be readily understood by those skilled in the art, may be supplied to addigional hydraulic apparatus such as another motor or the ike.

When it is desired to operate the motor 16, the operator makes a single manual adjustment by moving the operating handle 24 from the illustrated idle position. In accordance with an important feature of the invention, this single manual adjustment opens a path for flow to the motor and also establishes a flow rate for the flow to the motor, which rate is automatically maintained providing the pump flow is sufiicient. In the illustrated embodiment, the direction in which the handle is moved determines the direction of motor operation while the distance the handle is moved determines the motor speed.

More specifically, when the handle 24 is moved to an operating position, a restricted orifice of selected size is established in order to control the operation of the flow divider 20 so that a selected constant rate flow is channelled to the motor 16 and only the excess fluid, if any, flows through the power beyond port 62. Movement of the operating handle 24 is transmitted to the spool 22 by means of a pin 64 extending through the spool and received in a slot formed in the handle 24, and this movement is effective to establish communication between the inlet chamber 54 and an additional annular recess or chamber 66 communicating with the valve bore 28 and normally blocked from the chamber 54 by means of a land 22a on the spool 22. When the spool is moved from its idle position, restricted communication between the chambers 54 and 66 is established either by means of an opposed pair of recesses 68 or by another opposed pair of recesses 70 in the spool, depending upon the direction in which the spool is moved.

Preferably the recesses 68 and 70 are somewhat restricted or small in size, and are shaped so that as the spool is gradually moved away from the idler position, the total cross sectional area of communication between chambers 54 and 66 gradually increases from zero to some desired maximum. As appears below, the size of this area, which may be termed a variable restricted orifice, determines the priority flow requirement for the motor 16. In this manner, graduated positioning of the handle 24 results in a graduated sequence of constant flows.

The fluid passing through the restricted orifice defined by the spool 22 constitutes the priority flowi.e. the metered flow which is channelled to the motor 16. The direction in which the spool 22 is moved from the idle condition determines the direction of operation of the motor. In order to reach the motor, fluid flowing into the chamber 66 from the inlet chamber 54 passes through a passage 72 to a recess 74 along the bore 40, which recess always communicates with a counterbore 76 in the plunger 42 by way of ports 78 in the wall of the plunger. From the counterbore 76 fluid flows into a region 80 along the bore 40 and through an intersecting supply passage 82 to a supply chamber 84 along the main bore 28. In the idle position of the spool 22, the supply chamber 84 is isolated from a pair of motor chambers 86 and 88 by a spaced pair of lands 22b and 220 on the spool 22. The motor chambers 86 and 88- communicate with a pair of

motor ports

90 and 92 by way of a pair of motor passages 94 and 96.

When the spool is moved to the left from the position illustrated in FIG. 1, the supply chamber 84 communicates with the motor chamber 86, and the metered, priority fluid received through the supply passage 82 flow through the motor port 90 to the motor 16 to move the motor piston to the right as viewed in FIG. 1. Simultaneously, fluid from the opposite side of the piston returns through the motor port 92 to the chamber 88 and then into a tank chamber 98. Conversely, if the spool 22 is moved to the right from the position illustrated in FIG. 1, fluid is supplied to the motor by the way of the chamber 84, and the chamber 88 via the port 92 to the motor 16. Return fluid flows into the port 90, to the chamber 86 and then to a tank chamber 100. The

tank chambers

98 and 100 each communicate with a tank port 102 in the valve body 26, which tank port is connected to the reservoir or tank 14.

It can now be seen that when the valve spool 22 is manually moved to an operating position, the supply chamber 84 is interconnected with one of the motor chambers 86 and 88, and simultaneously a restricted orifice is established between the inlet chamber 54 and the chamber 66. The position of the flow divider plunger 42 is controlled by the pressure drop created by flow through the restricted orifice in order to maintain a constant flow through the orifice for a given orifice size. Excess flow over and above the constant priority flow is passed through the power beyond port 62.

More specifically, when the spool 22 is moved to a position determining a desired direction of operation of the motor 16 and determining a selected flow rate as determinated by the area of communication between the chambers 54 and 66, the flow divider valve thereafter automatically maintains a constant flow rate to the motor 16 independently of the pressure existing within the motor, and the pressure existing at the power beyond port 62. The constant rate priority flow passes through the recesses 68 or the recesses 70 to reach the motor 16. The pressure at the inlet side of the restricted orifice in chamber 54 is communicated to one end of the plunger 42 by way of the passage 56, the chamber 58, and a passageway 104 in the plunger 42. The pressure existing at the downstream side of the restricted orifice in chamber 66 is communicated to the opposite end of the plunger 42 by way of the passage 72, the recess 74, the port 78 and the counterbore 76. This pressure difierential acts on the plunger 42 against the force produced by loading spring 46, and the plunger is moved to an equilibrium position wherein the How through the port 62 is throttled to some extent by the land 42a on the plunger 42, and wherein flow into the passage 82 is throttled to some extent by a land 42b on the plunger. The two lands 42a and 42b throttle the flows to the port 62 and passage 82 to maintain a constant pressure differential across the plunger 42, which pressure diflerential is the same as that existing across the restricted orifice formed by the recesses 68 or the recesses 70. In this manner a constant flow rate for a given orifice size is supplied to the motor 16. The excess flow over and above the metered priority or constant flow passes through the power beyond port 62.

It will be apparent that if the pump 12 fails to supply a suflicient flow to satisfy the priority flow requirement, the entire flow from the pump will pass to the motor 16. This occurs because when an insufiicient flow passes through the adjustable orifice defined by the recesses 68 or 70, there is not a suflicient pressure build up across the orifice to move the plunger 42 far enough to open the power beyond port 62.

When the spool 22 is in its illustrated idle position, the pump 12 advantageously operates at a very low pres sure. In the idle condition, the only pressure requirement reflected to the pump is the pressure required to move the plunger 42 against the spring 46 to open the passageway 62. In this condition, the right hand end of the plunger 42 as viewed in FIG. 1 is vented to the low pressure tank port by way of a passageway 106 communicating with a groove 108 in the spool 22, which groove communicates with the tank chamber 100 by way of a passageway 110 formed in the body of the spool 22. In a typical installation, the pressure required to overcome the force of the spring 46 in the idle position of the spool 22 may be in the neighborhood of 50 pounds per square inch.

The novel valve construction 18 makes possible improved control of the speed of motor 16 because for any given setting of the operating handle 24, the flow of fluid to the motor 16 is metered at a constant rate. The rate may be adjusted to a very small amount in order to feather the load on the motor 16, or may be increased to any desired extent. The maximum speed of the motor 16 may be exactly regulated by the shape and/ or position of the recesses 68 and 70, or, as in the illustrated embodiment, by the provision of a spacer collar 112 associated with the centering mechanism limiting the distance that the spool 22 may be moved in either direction from the idle position. 7

Referring now to FIG. 2 there is illustrated a hydraulic circuit designated as a whole by the reference numeral and constructed in accordance with features of the present invention. The circuit 120 is adapted to control the operation of several hydraulic motors, and is illustrated in connection with a back-hoe attachment for an industrial tractor. Thus the circuit includes a pair of

double acting cylinders

122 and 124 for positioning the left and right Outriggers or spades at the rear of the vehicle; a double acting cylinder 126 for controlling the swing of the boom; a double acting cylinder 128 for controlling the crowd or inclination between the boom and the stick; a double acting cylinder 130 for controlling the inclination of the bucket with respect to the stick; and a double acting cylinder 132 for controlling the inclination of the boom with respect to the vehicle.

The double acting cylinders are controlled by means of

control valves

134, 136, 138, 140, 142 and 144, each of which is identical with the valve construction 18 illustrated in FIG. 1 and described in detail previously. These valves are shown in FIG. 2 only in outline form, and reference may be had to FIG. 1 and the corresponding description for particulars of their construction and operation. Elements of the

control valves

134, 136, 138, 140, 142 and 144 which have been identified with reference numerals in FIG. 2 have been provided with the same reference numerals as those used to identify corresponding elements of the valve construction 18 shown in FIG. 1.

Pressurized fluid for the system 120 is provided from a tank or reservoir 146 by means of a pump 148 delivering fluid to the inlet port 50 of the control valve 134, and the pump 148 may preferably be driven by the engine of the industrial tractor with which the backhoe attachment is associated. The various control valves are connected in cascade, that is, the flow from the power beyond port 62 of the first control valve 134 is supplied to the inlet 50 of the second control valve 136, and so forth. The excess flow from the final control valve 144 is supplied from its port 62 and returned to tank.

In accordance with an important feature of the present invention, the cascade connection between the flow divider valves associated with the control valves provides significant advantages in a system for controlling several motors. More specifically, each of the motors in the system operates independently of the others and there is no interaction between the circuit branches. In addition, the pressure requirement reflected to the pump is only slightly higher than the highest pressure demanded anywhere in the system.

In the condition illustrated in FIG. 2, each of the control valves is in its idle position and all of the hydraulic motors are inactive. In this condilion, the flow from the pump 148 passes through each of the control valves and is returned to tank. The pressure drop experienced in each of the control valves is very slight, being due only to passageway friction and the like. The pressure of the fluid passing through the valves may be in the neighborhood of 50 pounds per square inchi.e., the pressure required to overcome the loading springs and hold the flow divider plungers of the various valves in the position in which the ports 62 are opened. There may be an additional pressure drop of approximately 50 pounds per square inch across an orifice 150, the purpose of which will be explained hereinafter.

If the operating handle 24 of the control valve 134 is now moved from the idle position to produce operation of the motor 122 for the left outrigger, a priority flow of magnitude bearing a constant relation to the amount of handle displacement is established and channelled to the motor 122, the return flow being exhausted to tank through the tank port 102. The excess flow travels through the port 62 of the control 134 and flows to the inlet 50 of the control valve 136, and is thus available to any of the downstream controls and motors. If the

control valves

134 and 136 are operated simultaneously, independent priority flows are established for the

motors

122 and 124, and any excess is available to the four downstream controls. When two or more of the control valves are operated simultaneously, the corresponding motors receive metered, priority flows independently of any other pressures in the system, and operate at selected speeds without interaction between the motors. In addition, if all upstream control valves are in the idle position, the entire flow is available to any downstream motor. If the flow provided by the pump 148 is sufiicient all six of the motors may be operated simultaneously, each receiving a metered constant flow for constant speed operation at the speed selected by movement of the corresponding handle 24. The flow to some or all of the motors may be limited at selected maximum values.

In accordance with a feature of the present invention, the pump 148 may be controlled in accordance with system demand so that it supplies just enough fluid to satisfy the system at any given time. For this purpose, the return flow from the port 62 of the last control valve 144 is channelled through the restricted orifice 150 to establish a pressure upstream of the orifice 150, this pressure always being directly proportional to flow through the orifice. The pump 148 is illustrated diagrammatically as being of the variable displacement swash plate type, and is illustrated in the full displacement position. The pump is held in this position by means of a spring 152 acting against a piston 154 within a control cylinder 156 in the absence of flow through the orifice 150. When a predetermined flow through the orifice 150 is reached, the pressure existing upstream of the orifice 150 and acting against the piston 154 reduces the pump displacement. An equilibrium condition is reached wherein the pump supplies just enough fluid to meet the system demand plus a predetermined flow to the orifice 150, which for example may in the order of one-half of one gallon per minute.

Thus it can be seen that in the idle condition, the pump is required to supply only the very small flow required by the orifice 150 plus any leakage losses which may occur in the system. As soon as one of the operating handles 24 of one of the control valves is moved to operate one of the motors associated with the system, the flow through the orifice 150 decreases, the pressure acting on the piston 154 also decreases, and the pump is automatically moved by spring 152 to increase the displacement until the flow requirement of the operating motor is satisfied. If additional control valves are operated, the displacement of the pump is continually increased in order to meet the demands of the various valves.

In the event that the pump is unable to meet the system demand, as for example when the vehicle engine is operating at an idle speed, priority is established within the circuit by the cascade arrangement of the control valves. Thus the control valve 134 is served first in priority and if it uses all the available fluid, no fluid remains for the other motors. If the flow then slowly begins to increase, the

motors

124, 126, 128, and 132 are sequentially served in that order of priority.

It should be understood that the principles used in controlling the pump 148 in accordance with system demand may be applied as well to the arrangement of FIG. 1. This would be accomplished in the same manner as illustrated in FIG. 2 with the flow through the power beyond port 62 being used to control the displacement of a variable displacement pump.

Also, the pump displacement may be reduced in the event system pressure exceeds a predetermined valve. This is accomplished through a hydraulic circuit 160 from the pump discharge to a point upstream of the restricted orifice and control cylinder 156 and including a normally closed relief valve 162. The relief valve is set to open at a predetermined high pressure which may result, for example, from a motor being blocked mechanically. The resulting increased flow of oil through the orifice results In an increase in pressure acting on the cylinder 156 thereby to reduce the pump displacement and the pump output as to 1ts minimum value of one-half gallon per minute.

Although the present invention has been illustrated and described in connection with the details of a particular embodiment, those skilled in the art may devise other embodiments and modifications falling within the spirit and scope of the invention. For example, the principles of the invention are applicable to single acting valves as well as to the double acting valve illustrated. Accordingly, details of the selected embodiment do not limit the invention except as included in the following claims.

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

1. Value apparatus for controlling the operation of a fluid motor, said valve apparatus including an inlet passage for receiving a flow of pressurized fluid, a delivery passage for supplying fluid to the fluid motor, an additional outlet passage, and a pressure operated flow splitter valve comprising a restricted orifice in the path of fluid flowing through said delivery passage, said flow splitter valve further comprising a pressure operated plunger controlled by the pressure drop across said orifice for dividing the flow from the inlet passage into a priority flow to said delivery passage and an excess flow to said additional outlet passage, and a manually operated valve element including a first portion intersecting said delivery passage for controlling the application of fluid from the delivery passage to the motor, and a second portion spaced from the first portion for adjusting the size of the restricted orifice.

2. Valve apparatus as claimed in claim 1 wherein said plunger cooperates with said delivery and additional outlet passages to throttle said priority and excess flows to maintain the priority flow at a constant level determined by the size of said restricted orifice.

3. Valve apparatus as claimed in claim 1, said element comprising a spool having an idle position wherein said first portion blocks flow through the delivery passage, said adjustable orifice being closed in said idle position for establishing the priority flow requirement at zero. D

4. The valve apparatus of claim 3, an additional fluid motor adapted to receive said excess flow and receivlng the entire flow of pressurized fluid when said spool 1s in said idle condition.

5. The valve apparatus of claim 3, said spool belng movable in two directions from the idle position to op ate the fluid motor in two directions, said adjustable 01'1- fice being opened by movement of said spool in either direction.

6. The valve apparatus of claim 5 includmg me ns for limiting the maximum size of said adjustable orifice to a predetermined value, thereby to regulate the maximum eed of operation of the flu d IIlOtOf- 7. The valve apparatus of claim 1 further comprls l an additional pressure operated device for rece1v1ng said excess flow.

8. Valve apparatus for controlling the operation o a fluid operated device comprising:

an inlet passage adapted to receive a flow of pressurized fluid;

a delivery passage adapted to communicate with the fluid operated device;

an output passage;

a flow splitter valve receiving fluid from said inlet passage and including a pressure operated plunger for channeling flows to said delivery passage and said outlet passage in amounts determined by the pressure applied thereto;

a manually controlled member including a valve member movable between positions for blocking and opening said delivery passage;

an adjustable orifice in the path of fluid flowing through said delivery passage and defined in part by a portion of said manually controlled member spaced from said valve member so that movement of the valve member adjusts the size of the orifice;

and means for applying the pressure differential developed across said orifice to said pressure operated plunger;

said flow splitter valve including a loading spring urging said plunger to a position wherein said outlet passage is blocked and said delivery passage is open, and said applying means being arranged to apply said pressure dilferential in opposition to said loading spring to urge said plunger to a position wherein said delivery passage is blocked and said outlet passage is open.

9. Valve apparatus for supplying pressurized fluid to a fluid motor and comprising a housing having an inlet for receiving pressurized fluid, a delivery passage for channeling a flow of pressurized fluid from said inlet for the fluid motor, a drain passage for discharging low pressure fluid from the housing, a pair of motor ports for connection to the motor, a restricted orifice in the path of fluid flowing through said delivery passage, manually movable valve means for selectively intercommunicating said motor ports respectively with said delivery and drain passages and for simultaneously adjusting the size of said restricted orifice in dependence upon the extent of movement of said valve means, an outlet passage in said housing isolated from said drain passage, and a pressure operated valve including a plunger intersectingsaid delivery and outlet passages and controlled by the pressure drop across said orifice for establishing a priority flow in said delivery passage and an excess flow in said outlet passage, said plunger cooperating with said delivery and outlet passages to throttle said priority and excess flows thereby to maintain said priority flow at a susbtantially constant level determined by the size of saidorifice independent of pressure variations in said outlet and';delivery passages.

10. The. valve apparatus of claim 9, said manually movable valve means being movable in two directions for reversing the direction of operation of the motor.

11. The' valve apparatus of claim 9, said manually movable valve means comprising a single element having a first portion for selectively intercommunicating said motor ports and said delivery and drain ports, and said restricted orifice being defined at least in part by a second portion of said movable valve member spaced from said first portion.

12. In a hydraulic system the combination of a plurality of pressure operated flow dividers each having an inlet, a priority flow outlet and an excess flow outlet, each flow divider including a restricted orifice in the path of flow through its priority flow outlet together with a plunger controlled by the pressure drop across said orifice for throttling the priority and excess flows to provide a constant priority flow through the priority flow outlet determined by the size of the orifice and for providing an excess flow through the excess flow outlet, a plurality of fluid motors each associated with one of said flow dividers, a plurality of manually operated valves each connected to receive the priority flow from one of said flow dividers for controlling the application of the priority flow to the corresponding motor, each manually operated valve including means for adjusting the size of the corresponding restricted orifice thereby to establish the corresponding priority flow rate, and a pump for supplying pressurized fluid to the inlet of an upstream flow divider, the inlet of each downstream flow divider receiving fluid only from the excess flow outlet of the next preceding flow divider.

13. Apparatus for controlling the fiow of fluid from a source of pressurized fluid to a fluid operated device, said apparatus comprising:

housing means including a first bore;

a spool slidable in said first bore between an idle position and a range of operating positions;

an inlet chamber communicating with said first bore and adapted to receive pressurized fluid from the source;

an additional chamber communicating with said first bore and spaced from said inlet chamber;

a first land on said spool separating said inlet and additional chambers in the idle position of the main spool;

a motor chamber communicating with said first bore and adapted to communicate with the fluid operated device;

a supply chamber spaced from said motor chamber and communicating with said first bore;

a second land on said spool separating said motor and supply chambers in the idle position of said spool;

recess means in said spool adjacent said second land communicating said supply chamber and said motor chamber in all operating positions of said main spool;

an outlet passageway in said housing means communicating with said inlet chamber;

a upply passageway extending between said additional chamber and said supply chamber;

a second bore intersecting said outlet passageway and intersecting said supply passageway;

a flow metering plunger slidable in said second bore;

a spring urging said plunger toward a position for restricting said outlet passageway and opening said supply passageway;

means on said spool adjacent said first land for creating a restricted orifice between said inlet and additional chamber a said main spool moves from the idle position;

and means communicating said inlet and additional chambers with opposite ends of said plunger for urging said plunger to a position opening said outlet passageway and restricting said supply passageway in response to the pressure differential created by flow through said restricted orifice.

14. Apparatus as claimed in claim 13 further comprising a vent passage extending from said additional chamber to a region of low pressure, said vent passage intersecting said first bore, and mean on said spool for opening said vent passage only in the idle position of said spool.

15. A hydraulic circuit comprising means for supplying pressurized fluid, first flow divider means receiving fluid from said supplying means for providing a first priority flow and fo providing a first excess flow when the priority flow requirement is satisfied, first fluid utilization means receiving said first priority flow, second flow divider means receiving only the first excess flow from said first divider means for providing a second priority flow and for providing a second excess flow when the second priority flow requirement is satisfied, and manually operated adjustable means associated with said first flow divider means for decreasing the magnitude of the first priority flow requirement thereby to increase the flow to said second flow divider means when reduced flow is required by said first fluid utilization means.

16. The hydraulic circuit of claim 15, a manual control valve for controlling the application of said first priority flow to said first fluid utilization means, said adjustable means being controlled by operation of said manual control valve.

17. The combination of claim 12, each manually operated valve comprising a spool having a first portion mov able between positions to control the operation of the corresponding motor, said adjustable orifice being defined at least in part by a spaced second portion of said spool.

18. The combination of claim 12, means including a restricted orifice for conducting the excess flow from a downstream priority flow divider to a region of low pressure, said pump comprising a variable displacement pump, means including an over pressure relief valve connecting the pump discharge to a point upstream of said restricted orifice, and means for controlling the displacement of the pump in accordance with flow through said restricted orifice.

19. The combination of claim 18, said controlling means including a cylinder, a control piston in said cylinder and connected to said variable displacement pump, a spring acting on said control piston for normally maintaming said pump in its maximum displacement conditron, and means communicating the pressure existing upstream of said restricted orifice to said cylinder to overcome said spring and reduce the pump displacement when a predetermined flow through said orifice is achieved.

References Cited UNITED STATES PATENTS 2,102,865 12/1937 Vickers 60-52 2,247,140 6/1941 Twyman 91-414 2,354,634 7/1944 Griswold 60-53 XR 2,476,763 7/1949 Pettibone 91-447 XR 2,472,477 6/1949 Harrington et a1. 2,892,311 6/1959 Van Gerpen. 2,892,312 6/1959 Allen et al. 3,099,284 7/1963 Thrap et al. 137-117 3,145,734 8/1964 Lee et al. 137-59613 3,234,957 2/1966 Allen 137-117 EDGAR W. GEOGHEGAN, Primary Examiner US. Cl. X.R.