US2503870A - Flow regulating device - Google Patents

Description

April 11, 1950 F. T. HARRINGTON FLOW REGULATING DEVICE Filed May 3, 1946 y W A r m M w .m a Y B m v ql n l l l hnn Patented Apr. 11, 1950 FLOW REGUIATING DEVICE Ferris T. Harrington, Detroit. Micln, assignor to Vickers Incorporated, Detroit, Mich., a corporation of Michigan Application May a, 1946, Serial No. 667,170

This invention relates to power transmissions, particularly to those of the type comprising two or more fluid pressure energy translating devices, one of which may function as a pump and another as a fluid motor.

The invention is particularly concerned with flow regulating valves of the compensating bypass type for use in hydraulic transmissions containing a fluid pump, a reversible fluid motor, and throttling means for regulating the speed of the motor. This type of valve is used to maintain a constantly regulated flow of fluid through the throttle, doing this by being responsive to the pressure ahead of and beyond the throttle.

In the past where the speed of the motor was to be regulated in both directions and the throttling effect was to be produced by the partial opening of a directional control valve which enables the operator at will to selectively cause rapid transverse movement of the motor in both directions or variable feed movements in both directions at any time, it was deemed necessary to incorporate two compensating by-pass valves in the system, one for each throttle. I

Generally, in hydraulic systems having a pump and a reversible fluid motor, a directional control valve for reversing the operation of the motor and a throttle for each end of the motor, a compensating valve for each throttle was incorporated in the system.

It is an object of this invention to provide in such a hydraulic system having a directional control valve for reversing the direction of operation of the motor and having a throttle preferably of the variable type for each end of the motor, a single compensating by-pass valve for maintaining a constantly uniform pressure drop across both throttles.

It is a further object of this invention to provide for a hydraulic system as above stated, a simply constructed and economically manufactured compensating valve of the by-pass type which will be responsive to the pressure drop ahead of and beyond the throttle through which fluid is being directed by the directional control valve to the motor.

It is also an object of this invention to provide in a hydraulic system of the above type in combination with a compensating by-pass valve for the purposes before mentioned, a pressure responsive pilot control valve means causing the compensating valve to also perform the function of a relief valve.

Further objects and advantages of the present invention will be apparent from the following de- 9 Claims. (CI. 60-52) scription, reference being had to the accompanying drawing wherein a preferred form of the present invention is clearly shown.

In the drawing, the single flgure is a diagrammatic view of a simple hydraulic system moorporating a sectional view of a preferred form of the present invention.

Referring to the single figure, there is shown a pump in which is connected to a tank l2 by means of a suction conduit l4 and which is con nected by means of a pump delivery conduit I6 to an inlet port l6 of a flow regulating valve 28 also having a discharge port '22 and a by-pass port 24. The discharge port 22 is connected to a pressure port 26 of a four-way directional valve 28 by means of a conduit 36. The control valve 28' also has a tank port 32 connected to tank l2 by means of a conduit 34 and a pair of motor ports 36 and 38 which are connected to opposite ends of a reversible fluid motor, not shown, by means of conduits 40 and 42. The by-pass port 24 of valve 28 is connected to the tank conduit 34 by means of a conduit 44. The valve 20 also has two control ports 46 and 48, the former of which is connected to motor conduit 40 by means of a conduit 50, and the latter of which is connected to motor conduit 42 by a conduit 52. Two relief ports 54 and 56 are connected to a conduit 58 which is connected to conduit 44 by means of conduits 68 and 62, respectively, which intersects conduit 58.

Pressure port l8 and discharge port 22 of valve 28 are directly connected by means of a passage 64 to an inlet chamber 66. Control port 46 of valve 20 is connected to a first control chamber 68 by means of a passage I8 having a restriction I2 incorporated therein, and control port 48 is connected to a second control chamber 14 by means of a passage 16 also having a restriction l8 incorporated therein. A piston reciprocably mounted in a bore 82 so as to form the inlet and two control chambers previously mentioned within the bore 82 has a valve 84 formed at its lower end for controlling the opening and closing of a seat 86 and by-passing fluid through the seat 86 to an exhaust chamber 88 which is connected to exhaust port 24. A spring 90 of predetermined resistance biases piston 80 so that valve 84 closes seat 86. The piston 88 has a surface indicated by the numeral 92 continuously exposed to pressure in the inlet chamber 66 and a surface indicated by the numeral 84 opposed to the surface 82 which is adapted to be exposed to the pressure existing in motor conduit 42. A third surface at the extreme upper end of the piston 80 and indicated pressure beyond the throttle interposed in motor conduit 42 and the surface area 96 would be exposed to pressure beyond the throttle interposed in motor conduit 46, providing that these throttles were incorporated in the motor conduits 46 and 42 ahead of their intersection withconduits 56 and 52. respectively.

For the purpose of relieving excessive pressure fluid in the system, two pilot relief valves 68 and I66, the former of which is connected to chamber 68 by a passage I62 and the latter of which is connected to chamber I4 by a passage I64, will connect either chamber 68 or chamber 14 to the tank I2 whenever a predetermined maximum pressure has arisen in either of the motor conduits 46 or 42. The maximum pressure is determined by the resistance of duplicate springs I66 and I68 biasing valve I66 to a closed position. By connecting either chamber 68 or chamber 14 to tank I2, the pressure forces acting on either of the surfaces 64 and 96 opposing the pressure forces in the chamber 66 acting on surface 62 will become unbalanced and piston 86 will shift upwardly permitting valve 64 to open seat 86 to exhaust chamber 88 and pressure fluid from pump I6 will be by-passed therethrough to tank I2. Although separate throttles could be incorporated in motor conduits 46 and 42, the invention in its preferred form. for reasons of efliciency, economy and simplicity, makes use of the control valve 28 itself for producing a variable throttling effect in the motor conduit 46 and 42. For this purpose, any suitable conventional four-way directional control valve may be used providing that a throttling action may be provided in the motor conduits by the action of the shifting of the valve. Valve 28 contains a spool H6 having a centrally located land II 2 and lands H4 and II 6 to the left and right, respectively, of land H2. The spool H6 is also provided with a plurality of transverse ports located at the left of land II4, to the right of H6 and in land H2 indicated, respectively, by the numerals H3, H6 and H7, all of which are connected to a centrally located longitudinal passage H8, The spool H6 is reciprocably mounted within a bore I26 which is provided with a groove I22 connected to the pressure port 26, grooves I24 and I26 connected to the motor ports 36 and 38, respectively, and grooves I28 and I36 which are connected to the arms of a passage I32 which is connected to tank port 32. A handle lever I34 is connected to spool H6 for manual operation of the valve 28.

The operator in shifting spool I I6 may partially shift the spool to incompletely open the pressure groove I22 to either of the motor ports 36 and 38, and by gradually shifting said spool in either direction, may create a variable opening.

In operation, with the pump I6 running and with spool H6 shifted to the position shown, pressure fluid from pump III will be delivered by discharge conduit I6 to the inlet port I8 of valve 26 and by means of passage 64 fiowthrough the inlet chamber 66 to the outlet port 22 from whence it will be delivered to the pressure port 26 of valve 28 by means of conduit 86. Due to the fact that land H2 has almost completely uncovered pres-- sure groove I22, 9, rapid traverse movement of the motor will take place. Piston 66, only being responsive to the pressure drop across the throttle, will not in any way interfere with the full flow of fluid from pump I6 to the motor as long as a throttling effect is not produced by a partial shifting of spool H6. Due to the fact that the surface area 96 and the surface area 92 of pis ton 66 are equal and the pressure forces within chamber 68 and in the chamber 66 are equal, spring 96 will bias piston 66 so that valve 84 thereof will close seat 66. However, if spool H6 is shifted slightly to the right, pressure groove I22 will be partially closed so as to produce a throttle across land H2. In this case, pressure ahead of the throttle will be present in inlet chamber 66 of valve 26 and pressure past the throttle will be present in chamber 66 by means of'motor conduit 46, conduit 56, control port 46, passage I6 and restriction I2. The pressure drop across the throttle will unbalance the pressure forces acting on the surfaces 92 and 96, and piston 86 will shift upwardly permitting valve 84 to open seat 85 to exhaust chamber 88 and a quantity of fluid will be by-passed from pump I6 to tank I2, the remainder of which will be delivered by means of motor conduit 46 to the motor, not shown. Whenever the pressure drop across the throttle created by land I I2 of valve 28, however, becomes greater or less than the resistance of spring 96, the piston 66 will be shifted to open or close the seat 86 more fully so as to maintain the pressure drop across the throttle constant and thus maintain the flow to the motor from pump I6 constant. Fluid discharging from the motor through conduit 42 is delivered to motor port 36 and by means of groove I26, the plurality of ports III in land H2, passage H8, the plurality of ports 5, bore I26, passage I32, tank port 32 and conduit 34 is delivered to tank I2. Due to the fact that motor conduit 42 is directly connected to tank I2, chamber I4 will also be directly connected to tank I2 and, consequently, pressure forces will be lacking in said chamber to react on surface 94 and disturb the opposing pressure forces acting on surface 92 and surface 96. If the spool H6 is shifted completely to the right, pressure port 26 will be completely open to motor port 38 and motor port 36 will be connected to tank port 32. In this position of the spool III), a rapid traverse movement of the motor in the opposite direction will take place. However, if the operator shifts spool H6 to the left from the complete rightward position, a throttle across the land H2 through the motor port 38 will be created. As in the opposite directional feed movement of the motor, the pressure ahead of the throttle will be present in inlet chamber 66 but, in this case, the pressure beyond the throttle will be present in control chamber I4 so as to expose the surface area 94 of the piston 66 to the pressure beyond the throttle. Pressure fluid from pump III will be delivered by means of pump delivery conduit I6 to the inlet port I8 of control valve 26, and by means of passage 64 through the inlet chamber 66, through the outlet port 22 of valve 26 and through the pressure port 26 of valve 28 by means of conduit 36. Fluid will flow through groove I22 and across the throttle cre-' ated by land II 2 into motor port 38 and by means of motor conduit 42 to the opposite end of the motor, not shown, and by means of conduit asoaevo I! to control port 48 of valve 28, from whence by means of passage 18 and restriction 18, the pressure forces existent in motor conduit 42 past the throttle will also be present in the chamber I4.

Piston 88, because of the unbalancing of the pressure forces, will be shifted slightly so as to open the seat 84 slightly and a quantity of fluid will be by-passed through the tank i2, through exhaust chamber 88, tank port 24, conduit 44 and conduit 84, the remainder of said fluid flowing to the motor. If at any time the pressure drop across the land H2 becomes any greater or less than the resistance of spring 98, as in the former case, the pressure forces existing in inlet chamber 86 and chamber 14, acting on the opposing surfaces 82 and 84, will tend to shift the piston 88 so as to more fully open or close seat 88 in order to by-pass a sufllcient quantity of fluid to the tank I! in order to maintain the pressure drop across the land H2 uniformly constant. If at any time the pressure in conduit 42 exceeds the resistance of spring I88 maintaining valve I88 in a closed position, the valve I88 will shift and open the chamber 14 to tank l2. Due to the fact that the fluid in chamber I4 may bleed through the opening created by valve I08 faster than pressure fluid could enter chamber 14 through the restriction 18, the pressure forces in inlet chamber 86 and chamber 14 suddenly become unbalanced and the piston 88 is shifted upwardly so that the valve 84 completely opens seat 86 to the exhaust chamber 88 and the full flow of fluid from pump i II will be by-passed through the tank l2. Likewise, if at any time the pressure in motor conduit 40 should exceed a predetermined pressure as determined by the resistance of spring I86, valve 98 will shift and open chamber 88 to tank l2. The pressure forces then existing in chambers 88 and chamber 66 suddenly become unbalanced, and piston 80 will shift upwardly carrying valve 84 with it and opening seat 88 fully to exhaust chamber 88 thereby by-passing tinuously exposed to pressure before the throtties and having two other surface areas which are opposed and equal thereto which may bealternatively exposed to pressure past the throttles is a simple, economical and efficient manner of utilizing one flow regulating valve to maintain a constant pressure drop across 'both throttles.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In a hydraulic power transmission containing a fluid pump forming a source of pressure fluid and a reversible fluid motor the combination of a directional control valve for reversing the direction of operation of the motor, means in the control valve forming a pair of throttles, one for each end of the motor, during a predetermined range of shifting the control valve in each direction, and a single compensating by-pass valve for maintaining a constant pressure drop across either throttle selectively.

2. In a hydraulic power transmission containing a fluid pump forming a source of pressure fluid and a reversible fluid motor the combination of a directional control valve for reversing the direction of operation of the motor, means in the control valve forming a pair of throttles.

one for each end of the motor, during a predetermined range of shifting the. control valve in each direction, a single compensating by-pass valve for maintaining a constant pressure drop across either throttle selectively, and means responsive to a predetermined pressure for causing the compensating valve to perform the function of a relief valve.

. 3. A flow regulating valve of the by-pass type for use in a hydraulic system containing a fluid pump forming a source of pressure fluid, a reversible fluid motor, a. directional control valve for reversing the directional operation of the motor and a pair of throttles, one for each end of the motor, said flow regulating valve containing a piston having a surface area adapted to be continuously exposed to pressure ahead of the throttles, a second surface area associated with the piston and opposed to the first surface area adapted to be exposed to pressure beyond one of the throttles, a third surface area associated with the piston also opposed to the first area adapted to be exposed to pressure beyond the other throttle and valve means associated with the piston for regulating the flow of fluid to the motor, whereby the piston valve maintains a constant pressure drop across the throttfe through which fluid is adapted to flow to the motor.

4. In a hydraulic power transmission containing a fluid pump forming a source of pressure fluid, a reversible fluid motor, a directional control valve for reversing the direction of operation of the motor and a pair of throttles, one connected to each end of the motor, a flow regulating valve of the by-pass type containing a compensating valve for controlling the by-pass having first, second and third equal piston surface areas, the first of which is continuously exposed to pressure ahead of the throttles, and the second and third areas being opposed to the flrst surface area and selectively exposed to pressure past the throttles, whereby the single compensating valve selectively mantains a constant pressure drop across both throttles.

5. In a hydraulic power transmission containing a fluid pump forming a source of pressure fluid, a reversible fluid motor, a directional control valve for reversing the direction of operation of the motor and a pair of throttles, one connected to each end of the motor, a flow regulating valve of the by-pass type containing a compensating valve for controlling the by-pass having first, second and third equal piston surface areas, the first of which is continuously exposed to pressure ahead of the throttles, and the second and third areas being opposed to the first surface area and selectively exposed to pressure past the throttles, whereby the single compensating valve selectively maintains a constant pressure drop across both throttles, and duplicate means connected to the second and third surface areas responsive to predetermined pressure increases for causing the compensating valve to perform the'function of a relief valve.

6. A flow regulating valve for use in a hydraulic power transmission containing a fluid pump, reversible fluid motor, a directional control valve for reversing the direction of operation thereof hydraulically connected to the pump, toboth ends of the motor and to a return source and throttle means for each end of the motor, said flow regusistance biasing the compensating valve to close the by-pass, said compensating valve having a first piston'surface area adapted to be continuously exposed to pressure ahead of the throttles, a second surface area on said piston equal to the nrst area and opposed thereto adapted to be exposed to pressure beyond one of the throttles and a third surface area on said piston also equal to the first area and opposed thereto adapted to be exposed to pressure beyond the remaining throttle, whereby the compensating valve is responsive to pressure ahead of and beyond the throttle through which fluid is directed to the motor for maintaining a constant pressure drop across said throttle.

7. In a hydraulic power transmission containing a fluid pump, a reversible fluid motor, a directional control valve for selectively'directing fluid to and from the motor for either direction of operation thereof and conduits connecting the control valve to the pump, to both ends of the motor and to an exhaust source, said control valve having a range of travel in each direction providing a variable throttle for each end of the motor, a flow regulating valve comprising in combination a by-pass, a compensating valve for opening and closing the by-pass, and resilient means of predetermined resistance biasing the compensating valve to close the bypass, said compensating valve having a first piston surface area continuously exposed to pressure ahead of the throttles, a second surface area on said piston equal to the first area and opposed thereto exposed to pressure beyond one of the throttles and a third surface area on said piston also equal and opposed to the first area exposed to pressure beyond the remaining throttle, whereby the compensating valve is responsive to the pressure ahead of and beyond the throttle through which pressure fluid is directed to the motor for maintaining a constant pressure drop across said throttle.

8. A flow regulating valve for use in a hydraulic power transmission containing a fluid pump, a reversible fluid motor, a directional control valve for reversing the direction of operation of the motor hydraulically connected to the pump, to both ends of the motor and to a return source and variable throttle means for each end of the motor, said flow regulating valve comprising in combination a valve body having an inlet chamber adapted to be connected to the pump ahead of the throttles, means forming a by-pass conneeted to the inlet chamber, a piston reciprocably mounted in the body having a valve formedtherein for opening and closing the by-pass,

resilient means of predetermined resistance bi-' asing the valve to close the by-pass, a first surface area on the piston located within the inlet chamber and responsive to pressure therein, a second chamber adapted to be connected to a motor conduit beyond the throttling meanstherein, a second surface area on the piston equal in area and opposed to the first surface area located within the second chamber and responsive to pressure therein, a third chamber adapted to be connected to the other motor con-' duit beyond the throttling means therein, and

a third surface area on the piston also equal in area and opposed to the first surface area located within the third chamber and responsive to pressure therein.

9. A flow regulating valve of the by-pass type. for use in a hydraulic transmission containing a fluid pump, a reversible fluid motor and throttling means connected to each end of the motor com- 5 prising in combination means forming a lay-- pass, a compensating valve for opening and closing the by-pass, resilient means biasing the compensating valve to close the by-pass, a first surface area on the compensating valve responsive 3 to pressure ahead of the throttles, a second surface area opposed to the first area and equal thereto responsive to pressure past one of the throttling means in opposition to the first mentioned pressure and a third surface area also opposed to the first area and equal thereto responsive to pressure beyond the remaining throttling means in opposition to the first mentioned pressure whereby the compensating valve is responsive to the pressure drop across the throttle 40 through which fluid is adapted to flow to the motor for maintaining a uniformly constant flow through said throttle.

' FERRIS T. HARRINGTON.

REFERENCES crrao The following references are of record in the I file of this patent:

UNITED STATES PATENTS

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