US2502800A - Pressure fluid differential type motor and control valve means therefor - Google Patents

Description

April 4, 1950 w. E. RENICK PRESSURE FLUID DIFFERENTIAL TYPE MOTOR- AND CONTROL VALVE MEANS THEREFOR Filed Oct. 7, 1948 r INVENTOR. WENDELL E. RENICK Patented Apr. 4, 1950 I'li TED ES PATENT OFICE PRESSURE FLUID DIFFERENTIAL TYPE MOTOR AND CONTROL VALVE MEANS THEREFOR Wendell E. Renick, Grove City, Ohio, assignor to The Denison Engineering Company, Columbus,

Claims. 1

This invention relates generally to hydraulic apparatus and is more particularly directed to control mechanism for use in a'hydraulic system, to govern the operation of a reversible fluid motor. It is still more particularly directed to 5 thereby. valve mechanism employed to regulate the flow A further object of the invention is to provide of fluid pressure from a source thereof to effect control valve mechanism for a hydraulic systhe operation of a reciprocating fluid pressure tem, including a source of fluid pressure and a operated device, the valve mechanism being parpower unit of the piston and cylinder type, the ticularly designed for use in connection with a control mechanism having a body, a manually hydraulic press. operated spool member and a plurality of pres- An object of the invention is to provide a consure responsive valve elements, the body, the trol valve mechanism for use in-a hydraulic sysspool member and valve elements providing fluid tern employing a source of fluid pressure and a passages to establish communication between the power unit of the piston and cylinder type, the source of fluid pressure and the rod end of the control valve mechanism being partially operpower cylinder and between the other end of the ated manually and partially automatically. power cylinder and exhaust in one position of It is also an object of the invention to prothe manually operated spool, the latter end of vide control valve mechanism to govern an opthe power cylinder being connected with the eration of a ram of a hydraulic press, which consource of fluid pressure, in another position of the trol valve mechanism is operative to cause the spool, the pressure responsive valve elements rapid traverse of the ram of a press, a slow pressbeing operative when the manually operated ing operation thereof and an additional rapid member is in the latter position to connect the traverse portion at the conclusion of the pressrod end of the power cylinder with the source of ing operation, the change from the rapid traverse fluid pressure when pressure exists in such rod speed to slow pressing speed and vice versa, takend of the cylinder and to connect the rod end ing place automatically without the attention of of the cylinder to the exhaust, when the pressure the operator. in such rod end decreases beyond a predeter- A still further object of the invention is to mined extent, the latter connection being effected provide a control valve mechanism having an by the pressure of the fluid source, inlet port connected with a source of fluid pres- Another object of the invention is to provide sure, a pair of cylinder ports connected with opa control valve mechanism having a body with posite ends of a power cylinder and exhaust ports, an inlet port, upper and lower cylinder ports and the mechanism having valve elements operative exhaust ports and a manually operated spool in one position to connect the first end of the 5 valve member having grooves for establishing power cylinder with the pressure source and the communication between certain of the ports in second end with the exhaust and to connect the the body, the spool member also having an insecond end of the power cylinder to the power ternal chamber for the reception of spring source in other positions of the elements, the pressed valve elements employed to control comelements being responsive to the fluid pressure munication between laterally directed ports exin the first end of the power cylinder, when the tending from the internal chamber in the spool second end thereof is connected with the pressure valve member to the exterior thereof, the spring source, to connect the first end of the power pressed members and ports being so located that cylinder to the fluid pressure source also, the eleone of the spring-pressed members will be rements also being responsive to the pressure of sponsive to fluid pressure existing in the lower the source when such pressure increases to a cylinder port and the other spring-pressed mempredetermined extent, to connect the first end of her being responsive to fluid pressure existing in the power cylinder with exhaust. By connectthe inlet port; both of the spring-pressed meming the first end of the power cylinder with the bers being operative when the manual spool is pressure source, the effective area of the piston in position to establish communication between in the power cylinder will be reduced making the a predetermined set of ports in the body. entire volume of the source of fluid pressure ef- Further objects and advantages of the presfective upon the reduced area of the piston to ent invention will be apparent from the followcause the same to move at a rapid rate. When ing description, reference being had to the acthe first end of the power cylinder is connected companying drawing wherein a preferred form 2 with exhaust the total area of the piston is exposed to the entire volume of fluid fromthe pressure source thus decreasing the rate of travel of the piston and increasing theforce developed of embodiment of the invention is clearly shown.

In the drawing:

Fig. 1 is a diagrammatic view of a. hydraulic system in which a valve formed in accordance with the present invention has been incorporated.

Fig. 2 is a fragmentary, sectional view showing the valve with the elements thereof in position to secure fast traverse of a piston in a power cylinder.

Fig. 3 is a similar view showing the valve elements in position to secure a reduced rate of movement of the piston at increased force.

Referring more particularly to the drawing, the numeral designates, generally, a hydraulic system, this system being employed in a manually controlled hydraulic press. The system 20 m cludes a reservoir 2 I, a power driven pump 22 and a relief valve 23 these elements together with connecting lines 24, 25 and 26 forming a source of fluid pressure. Line 24 extends from the reservoir to the pump 22, line 25, extending from the pump to the relief valve and line 26 extending from the relief valve to the reservoir 2i to direct fluid to the latter when the pressure in the system exceeds a predetermined degree. Another line 21 extends from the relief valve and pressure source to the control valve mechanism 28 forming the subject matter of the invention, this control valve mechanism serving to govern the flow of fluid pressure from the pressure source to a power unit 30 of the piston and cylinder type. This power unit includes a cylinder 3!, a piston 32 disposed for reciprocation in the cylinder and a ram 33 extending from the piston 32 through the bottom wall of the cylinder to perform useful work.

It is to be understood that although the ram is shown and specified as extending through the bottom wall of the cylinder, the cylinder could be so positioned that the ram would extend through an end wall in a horizontal angular or upward direction, if desired, the power cylinder being shown with the ram extending downwardly, merely for the purpose of illustration.

The control valve mechanism 28 includes a body 34 having a bore 35 for the reception of a spool member 33, the body also having a plurality of annular grooves spaced longitudinally of the bore 35, the grooves being designated by the numerals 31 to 4i inclusive. Groove 31 is disposed between grooves 38 and 39, while grooves 49 and 4i are disposed on the opposite sides of grooves 38 and 33 from the groove 31. The latter groove is connected with line 21, to receive fluid from the pressure source and grooves 38 and 33 are connected by lines 42 and 43 with the lower and upper ends respectively, of the power cylinder 30. Grooves and 4| are connected by line 44, which incidentally, may be a passage in the body 34, line 44 being connected by line 45 with the reservoir 2 l.

Spool member 36 is of generally cylindrical formation and is provided at its upper end with a head 46 to limit the downward movement of the spool member in the body 34. When the spool member is disposed with the head in engagement with the top surface of the body 34 an external groove 41 formed in the spool will establish communication between grooves 31 and 38; fluid pressure admitted from the source to groove 31 may then flow from this groove to groove 38 from which it will flow through line 42 to the lower end of the power cylinder. The force of this liquid under pressure will be exerted upon the under side of the piston 32 to move the same in an upward direction, fluid above the piston 32 being exhausted from the power cylinder through 4 line, 43 to groove 33. This fluid is conducted through a second groove 43 formed in spool member 36 to groove 4| from which it will flow through lines 44 and 45, to the reservoir 2 I.

When the spool valve 35 is in the position shown in Fig. 1 the piston 32 and ram 33 will move in an upward direction. As the piston approaches the upper end of the power cylinder an arm 50 secured to the ram will engage a collar 5i flxed to a shipper rod 52 depending from the lower end of the spool valve 36 and move this spool valve in an upward direction until the unreduced portion of the spool valve at the lower end of the groove 41 blocks groove 38 and prevents communication thereof with inlet groove 31; the piston and ram will then stop moving. When it is desired to cause the piston and ram to move in the opposite direction, the spool valve 36 is elevated by the manual operation of a pivoted lever 53 connected to the lower end of the shipper rod 52 to raise the spool valve 36 to the position shown in Figs. 2 and 3; with the spool valve in this position, groove 41 establishes communication between inlet port 31 and the upper cylinder port 33 and fluid may then flow from the pressure source through grooves 31, 41 and 39 to line 43, which extends to the upper end of the power cylinder. This fluid will be applied to the upper end of the piston 32 and will tend to move this piston in a downward direction, the force of the fluid being exerted on the upper side of piston 32 and transmitted therethrough to the fluid below the same causing this fluid to be under pressure also. This pressure will be transmitted through the line 42 to groove 38 and a third groove 54 formed in the spool valve 36.

In registration with the groove 54, the spool 36 is provided with lateral ports 55, which extend to an internal chamber 56 formed in the spool valve. This chamber extends into the spool valve from the upper end thereof and is formed for the reception of an insert 51, valve elements 58 and 60, springs 6i and 62, a spring abutment '63 and a plug 64, the latter closing the open upper end of the chamber. Insert 51 is disposed in the lower end of the chamber and is provided with a central bore 65, an external groove 66 and lateral ports 61 extending from the bore 65 to the groove 66. The spool member 35 is provided with lateral ports 58 in registration with the groove 66, the spool member 36 also having an external groove 10 in registration with the ports 68. Valve element 50 extends into the bore 65 and is provided with an annular groove 1| around the portion normally disposed in bore 65. The upper end of the insert 51 terminates immediately below the ports and provides a shoulder which co-operates with the shoulder at the upper end of groove 1i to govern fluid flow to such groove. The insert is stationarily positioned in the chamber either by being pressed into place, or, otherwise retained. Valve element 58 is of sleeve-like form and surrounds the stem portion of valve element 60, the element 58 being slidable both in the chamber 55 and on the stem of element it is normally urged in a downward direction into contact with the upper end of the insert 51 by the spring 6i. The body portion of element 68 is reduced to provide an annular passage designated by the numeral 12, which communicates at its lower end with ports 55. At its lower end, the body of element 58 is notched as at 13 to expose the stem of element 60 to fluid disposed in passage 12.

When valve member 38 is in the position shown in Fig. 2, fluid pressure in grooves 38 and 54 may flow through ports 55 to passage 12, the forceof this fluid pressure being exerted on the downwardly facing shoulder at the upper end of element 58. The force of this fluid will move element 58, upwardly in opposition to spring 85 until passage l2 communicates with ports l4 formed in spool 36, these ports at this time, being in registration with groove 31. The fluid in the lower portion of the power cylinder may thus flow through line 42 to groove 38 and through groove 54 and ports 55 to groove 12, the fluid then flowing through ports 14 to groove 31, where it,

will mix with fluid flowing from the pressure source and be conducted through grooves 47 and 39 and line 43 to the upper end of the power cylinder.

It should be obvious that with fluid flowing directly from the under side to the upper side of the piston, the entire volume of fluid flowing from the pressure source will be applied to the area of the piston 32 corresponding to the diameter of the ram 39. Due to this reduction in effective area of the piston 32, this member and the ram 33 will be caused to move at a rapid rate. Of course, the reduction in area will also cause a reduction in force developed by the piston, but suiflcient force will be exerted to move the ram at the increased rate. When the ram engages an article of work disposed in registration therewith the opposition offered will cause the fluid pressure of the source to increase. The increased pressure will exist in the inlet port 3'7, the grooves and lines connected therewith and in the upper end of the power cylinder. This increased pressure will be transmitted from the groove 5? to the interior of the spool 36 through other lateral ports '55 formed therein, ports '35 being disposedabove the valve element 58. but below a head it formed at the upper end of the valve element 50; this valve element 60 is normally urged in a downward direction by the spring 5.2. which is disposed between the head of valve 58 and the abutment 63. Spring 62 has greater strength than spring 6i so that valve 60 will be held stationary when valve 58 is moved by fluid pressure. The fluid pressure flowing through ports 75 will be applied to the under side of the head l6 and tend to move the valve element 60 upward in opposition to the spring 62. If the fluid pressure is of sufflcient magnitude, the valve element 60 will move upwardly until the groove H establishes communication between ports 55 and ports 67. At this time, the bottom or lower cylinder port 38 will be connected with exhaust port 40 and fluid may then flow from the under side of the piston 32 to the reservoir 2|. At this time valve element 53. if it has not already done so, will be returned to its normal lowered position wherein ports i i are prevented from communicating with ports t5. Since the communication between the upper and lower sides of the piston 32 is then interrupted and the under side of the piston is connected with the reservoir the entire top surface area of the piston will be exposed to the full volume of fluid from the pressure source; this will increase the force developed by the ram and cause it to continue the pressing operation. The rate of movement of the ram will be reduced, however, since the volume of fluid from the pressure source is being applied to the entire top surface area of the piston. If the ram moves through the article of work and the resistance to movement thereof is reduced, the fluid pressure above the piston will diminish, permitting spring 62 to move valve element 60 to the position wherein communication between ports and 61 is interrupted. There will then be no outlet for the fluid beneath the piston and the pressure on the fluid in the lower end of the power cylinder will increase; if it increases sufflciently, it will again move valve element 58 upwardly as previously described, until the lower or bottom cylinder port 38 communicates withthe inlet 'port 31 and the piston and ram may again move at the rapid rate.

When the rain has moved downwardly to a predetermined extent, the arm 50 will engage a second collar H on the shipper rod 52 and move the valve spool downward to a position wherein communication will be interrupted between the inlet port 31 and the top Cylinder port 39. The parts of the valve will then be substantially in the positions shown in Fig. 1. The ram will then stop moving downwardly and since groove 47 then establishes communication between ports 3'! and 38, the fluid from the pressure source will be directed to the bottom of the power cylinder; the ram will immediately move to its elevated, or, retracted position, the upper end of the cylinder being connected with exhaust at this time.

As previously mentioned, the final stage of movement of the piston and rain in an upward direction will move the valve spool 36 to a position wherein the flow of fluid from the pressure source to the lower end of the power cylinder will be interrupted. The ram will remain in this position as long as the valve spool 36 is stationary. A new cycle of operationof the ram may be initiated by again depressing the knob at the outer end of the lever 53.

From the foregoing, it will be apparent that a control mechanism has been provided. which will permit an operator to depress and hold the manual cont ol element of the press, provided with the control mechanism. Without further attention, the ram will then move at a rapid rate until the work is engaged by the ram, then the maximum force will bedeveloped to cause the ram to move through the work after which the rapid movement of the ram will be automatically resumed. Due to the particular construction of the control valve mechanism, movement of the ram, when it is not opposed, will create a back pressure in the lower end of the power cylinder, which pressure is utilized to establish communication between the lower and upper ends of the power cvlinder. This communication reduces the effective area*of the piston to the difference between the diameter of the piston and the exposed area of the under side. so that the full volume of fluid from the pressure source is exerted on the reduced piston area. By so reducing the area and exposing the same to the full volume of the pressure source the ram will be caused to move at a rapid rate. When the movement of the ram is opposed with a force sufflcient to interrupt movement of the piston, the back pressure will fall and the pressure above the piston and in the pressure source will increase; this pressure is then utilized to establish communication between the lower end of the power cylinder and exhaust, so that the full area of the piston becomes efi'ective and is exposed to the full volume of the pressure source. The force then developed by the piston and ram will be increased. while the speed of movement of the ram will be decreased. This transition will occur as many times as the ram is opposed by a sufficient force during its movement from one end amaeqo.

of the power cylinder to the other in a; forward stroke. When the opposition to the movement of the ram is interrupted, the control mechanism will again operate to cause the ram to move at the increased speed.

While the form of embodiment of the present invention as herein disclosed constitutes a prel'erred form, it is to be understood that other forms might be adopted, all coming within the 4 scope of the claims which follow:

I claim:

1. In a hydraulic press, a source of fluid under pressure; a power cylinder; control mechanism between said pressure source andsaid cylinder comprising a body having inlet, upper. and lower cylinder and exhaust ports; a valve spool disposed for movement in said body to selectively connect-certain of said ports, said spool having an internal chamber, external grooves andlateally directed ports extending from said chamber to said grooves; and spring-pressed spool elements disposed for movement in the chamber in said first-mentioned valve spool, said spool elements being responsive to fluid pressure-to move to positions establishing communication between certain of the-laterally directed ports in said first-mentioned spool.

2. In a hydraulic press, a source of fluid under pressure; a power cylinder; control mechanism between said presure source and said cylinder comprising a' body having inlet, upper and lower cylinder and exhaust ports; a valve spool disposed for movement in said body to selectively connect certain of said ports, said spool having an internal chamber, external grooves and laterally directed ports extending from said chamber to said grooves; a spring pressed spool element disposed for movement in the chamber in said first mentioned valve spool, said spool element being responsive to fluid pressure in said lower cylinder port to move to a position establishing communi cation between said lower cylinder port and said inlet;' and a second spring pressed spool element movably disposed in the chamber in said firstmentioned spool said second-mentioned spool being moved by fluid pressure in said inlet port to a position establishing communication between said lower cylinder port and an exhaust port.

3. In a hydraulic press, a source of fluid under pressure; a power cylinder; control mechanism between said pressure source and said cylinder comprising a body having inlet, upperand lower cylinder and exhaust ports; a valve spool disposed for movement in said body to selectively connect certain of said ports, said spool having an internal chamber, external grooves and laterally directed ports extending from said chamber to said grooves; said spool being movable to a position in which one groove establishes communication between said inlet and said upper cylinder port, a port in said spool communicating at this time with the lower cylinder port; a yieldably-pressedspool element in the chamber in the first-mentioned spool, said element being responsive to fluid pressure in said bottom cylinder port to move to a position establishing communication between said bottom cylinder port and. said inlet; and a second yieldably pressed spool element in the chamber in the first-mentioned spool, said second element being responsive to fluid pressure in'said inlet port to move to aposition establishing communictaion between said bottom cylinder port and an exhaust port.

4. In a hydraulic press, a source of fluid pressure; a power cylinder; control mechanism between said pressure source and said cylinder comprising a bodyhaving inlet, upper and lower cylinder and exhaust ports; a valve spool disposed for movement in said body, said spool having external grooves operative in one position of said spool to establish communication between said inlet and saidlower cylinder port and between said upper cylinder port and an exhaust port, one of said grooves establishing communication between said inlet port and said upper cylinder port in another position of said spool; a chamber in said spool; a-plurality of passages extending laterally from said chamber to the exterior of said spool; and first and second valve elements disposed-for movement in the chamber in said spool, said first element being responsive to pressure in said lower cylinder port when said spool is in the second-mentioned position to establish communication between said lower cylinder port and said inlet, said second valve element being responsive to pressure in said inlet also in the second position of said spool to establish communication between said lower cylinder port and an exhaust port. 5. In a hydraulic press, a source of fluid pressure; a power cylinder; control mechanism ,between said pressure source and said cylinder comprising a body having inlet, upper and lower cylinder and exhaust ports; a valve member disposed for movement in said body; passage-forming means in said member operative in one position thereof to establish communication between said inlet and said lower cylinder port and between'said upper cylinder port and'an exhaust port, said passage forming means establishing communication between inlet and said upper cylinder port' in another position of said member; means in said body responsive to the fluid pressure in said lower cylinder port when said member is in the latter position to establish communication between said lower cylinder port and said inlet; and additional means in said body responsive to fluid pressure in said inlet port when said member is in said latter position to establish communication between said lower cylinder port and an exhaust port.

- WENDELL E. RENICK.

No references cited.

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