US2098425A - Control mechanism for pumps - Google Patents

Description

1937. H. w. LANDENBERGER 2,098,425

CONTROL MECHANISM FOR PUMPS Filed March 26, 1935 5 Sheets-Sheet 1 k3 [7778/7 for Nov. 9, 1937.

H. w. LANDENBElGER 2,098,425

CONTROL MECHANISM FOR PUMPS Filed March 26, 1935 3 Sheets-Sheet 2 Nov. 9, 193 7.

CONTROL MECHANISM FOR PUMPS Filed March 26, 1955 3 Sheets-Sheet 5 50 R [Q 5 I 56 I Z I I 5/J 6- k7 Z0 -25 /.s /0 I /7 l? J r /4 /5 j 7 5 i z Z3 i 1/ .aa 34 J3 z! w 23 I I a] II I 35 l Patented Nov. 9, 1193? UR ETS if: i.

signcr to American Engineering Company,

Philadelphia, Pa, a corporation of Pennsylvania Application March 26, 1935, Serial No. 13,096

9 Claims.

This invention relates to control mechanisms, and, more particularly to mechanisms for controlling the operation of pumps.

One object of the present invention is to pro- 3 vide an improved control mechanism for pumps, which functions to maintain the pump on stroke throughout a predetermined pressure range in the system, to actuate the stroke adjusting means toward neutral position when the pressure in the system exceeds a predetermined value, and under predetermined conditions to maintain the pump on leakage stroke at a comparatively low pressure.

A more specific object is to provide a control mechanism for pumps which comprises a pair of rams, one of said rams being constantly connected to the pressure in the system while the other is connected thereto only under predetermined conditions at which time both rams function to maintain the pump on leakage stroke.

Other and further objects will become apparent as the description of the invention progresses.

Of the drawings, Fig. 1 is a diagrammatic view of the fluid control system showing certain of the elements thereof in section.

Fig. 2 is a side elevational view partly in section, of the high pressure pump and the control mechanism associated therewith.

Fig. 3 is a side elevational view of a portion of the control mechanism associated with a high pressure pump.

Fig. 4 is a diagrammatic view partly in section of the hydraulic press and a portion of the hydraulic circuit including the control'valves, showing the flow of fluid in the system when one of the valves is moved to its upper position of adjustment, and,

Fig. 5 is a similar view showing the flow of fluid in the system when both valves are.moved to their upper position of adjustment.

Referring to the drawings, the numeral 5 designates generally the fluid control system, which in the present instance comprises a pump unit 2, manually actuated valves A and B, automatic valve C, and an hydraulic press 3.

The pump unit 2 comprises a high pressure pump H and a low pressure pump L, suitably mounted upon a supply or makeup tank T. Pumps H and L are of the general type shown and described in the United States Patent No. 1,077,- 979, and in the present instance are driven by an electric motor M. Fluid is drawn into pump H from makeup tank '1 through a pipe 4, and is discharged from said pump through. a pipe 5. Pipe 5 is connected to a central port 6 of valve A. 'In a like manner fluid is drawn into pump L from tank T through a pipe land is discharged therefrom through a pipe 8. Pipe 8 is connected to pipe 5 and by means of a check valve 9 a reverse flow of fluid therein to pump L is prevented.

Valve A is provided with a substantially cylin- 5 drical chamber ill in which a pair of spaced interconnected valve members H and i2 operate. These valve members may be shifted by a lever I3 pivoted at one end to a link 14 which in turn is pivoted to a bracket l5 secured to and extending outwardly from valve A. Valve A in addition to port 6 has provided in the casing thereof ports l6 and I1, communicating with chamber l0, and a passage i9 which connects the opposite ends of chamber l0 communicates with a fourth port [8. 15

Press 3 comprises an upper cylinder having a piston 2| operating therein, a lower cylinder 22 having a piston 23 operating therein, and an intermediate stationary forming mold 24. Piston 2| is provided with a reduced portion 25 form- 20 ing with the inner walls of cylinder 20 an annular chamber 26, and to the end of which is secured a forming platen 21. Piston 23 has secured to the upper end thereof a holding platen 28. The purpose of platens 21 and 28 will appear fully 25 hereinafter.

Valve B is also provided with a cylindrical chamber 29 having spaced interconnected valve members 30 and 3| operating therein. Valve members 30 and 3| may be shifted by a lever and 30 link mechanism 32 similar to that shown in connection with valve A. Valve B has provided in the casing thereof ports 33, 34 and 35 which communicate with chamber 29.

Valve C comprises an upper chamber 36, an 35 intermediate chamber 31, and a lower chamber 38. The upper chamber 36 is connected to pipe 8 by a branch pipe 39, and has provided therein a valve 40 which normally prevents the passage of fluid to intermediate chamber 31 through the 4 connecting passage 4|. A coil spring 42 extends between valve 40 and a spring seat 43 provided at the upper end of said chamber and a set screw 44 is provided to adjust the tension of said spring.

A pipe 45 connects intermediate chamber 3'l-with 4.5 makeup tank T. Lower chamber38 has provided therein a comparatively large piston 46, the reduced portion 41 of which extends upwardly through and is guided in a cylindrical opening between chambers 31 and 38. The upper end of reduced portion 41 engages the lower end of the stem 48 of valve 40. A pipe 49 connects pipe 5 with the lower end of chamber 38. It therefore is evident that when the pressure in the system exce ds the tension of spring 42 piston 46 will unseat valve 46 and thus permit the discharge of pump L to bypassto makeup tank T through chamber 28, passage 4|, chamber 31 and pipe 45.

Returning to valves A and B, it is seen that a pipe 56 connects the upper end of cylinder 26 with port l6 of valve A. A pipe 5! connects port I! of valve A with a pipe 52; one end of the latter is connected to the lower end of cylinder 26, while the other end thereof is connected to port 35 of valve B. A pipe 53 connects the lower end of cylinder 22 with port 33 of valve B, and a pipe 54 connects port 34 with makeup tank T. A check valve 55 is provided in pipe 52 tonormally prevent a reverse flow of fluid from cylinder 22. A branch pipe 56 having a check valve 51 provided therein connects pipes 56 and 52 as shown in Fig. 1, and a pipe 58 connects port l6 of valve A with makeup tank T. A comparatively small pipe 56 connects discharge pipe 5 of pump H with a fluid motor 66 mounted at one end of pump H, while a second pipe 6| connects pipe 52 with a second fluid motor 62 mounted at the opposite end of said pump. Fluid motor 66, therefore, is always connected to the pressure in the system, while fluid motor 62, it will be observed, is connected to the pressure in the system only when fluid enters the lower end of cylinder 26.

Motor 66 in the present instance comprises a bracket 66 secured to the pump casing in any suitable manner, such as by bolts 64, and has provided therein a cylinder 65 in which operates a piston 66. Cylinder 65 communicates with a port 66' to which one end of pipe 59 is connected. A gland 61 secured to bracket 63 provents leakage past the piston 66. The left hand end of piston 66 (Fig. 2) abuts against a crossbar 68 through the opposite ends of which extend a pair of rods 66 and 16, the inner ends of said rods being secured to the sliding block ll of pump H, as shown in Figs. 1 and 2. A pair of nuts 12 and 18 provided at the outer end of rods 66 and 16 respectively, secure crossbar 68 thereto and permit adjustment of said crossbar to and from the piston 66. Secured to rods 69 and 16 intermediate the ends thereof are a pair of blocks I4 and 15 respectively, to which are pivotally connected the lower ends of a pair of. levers 16 and 11. These levers are pivoted intermediate their ends on a rod 16 mounted in bracket 66, as shown more particularly in Figs. 2 and 3, and are pivotally attached at the upper ends thereof as shown at 19, to pintles provided on the outer ends of a crosshead 66. Crosshead 86 is slidably mounted on a rod 6| secured to-the upperend of bracket 66 in any suitable manner, such as by a. nut 82. Rod 6| has provided thereon a coil spring 66 which extends between a spring seat 66 mounted adjacent crosshead 66 intermediate the ends thereof, and an adjustable spring seat 85. Spring seat is mounted near the right hand end of rod 8i, and may be adjusted by means of nuts 66. By this arrangement, it is seen, that when spring 66 is compressed it will urge croahead 66 to the left (Fig. 2) causing levers I6 and TI to swing in a counterclockwise direction, which through their connection with rods 68 and 16 place the pump H on stroke in a well known manner. Pump H will remain on stroke until the pressure in the system exceeds the tension of spring 66. when piston 66 willswing the levers I6 and H in a clockwise direction, thereby placing the pump on leakage stroke.

Motor," comprises a cylinder 61 having .a piston 48 operating therein. Cylinder 61 is accured to the right hand end (Fig. 2) of pump 11 by means of bolts 66, as shown in Figs. 1 and 2. The free end of piston 66 engages a crossbar 66 having secured to the opposite ends thereof a pair of rods 6| and 92, the inner ends of which are connected to sliding block ll of pump H. A gland 63' secured to theleft hand end of cylinder 61 prevents leakage of fluid past said piston. Cylinder 81 is provided with a port 94 to which pipe 6| is connected. From this arrangement it is seen that when pressure is applied to motor 62, sliding block ll will tend to move to the left.

From the above description, the operation of my improved control mechanism is believed to be obvious. Howevenin order to correlate the various elements, a brief rsum of the operation thereof will now be given.

The operator first adjusts the tension of spring i2 of valve C the desired amount; for example, if it is desired that fluid discharged from the low pressure pump should bypass when the pressure in the system exceeds I56 pounds per square inch, spring 42 is adjusted to retain valve 46 upon its seat until this pressure is exceeded. In a like manner, the tension of spring 83 is adjusted the desired amount, say, for example, to resist a pressure in the system of 1000 pounds per square inch at the end of the compressing action thereof. Valves A and B are then adjusted to the position shown in full lines in Fig. l. The apparatus is now conditioned for operation.

Fluid from pumps H and L will now discharge into the annular chamber 26 of cylinder 26 through pipes 5 and 6, valve A, and pipes II and 52. Fluid will' also flow to the lower end of cylinder 22 through pipe 52, check valve 65, valve B, and pipe 53. Pistons 2i and, will now move upwardly until platen 28 engages the lower end of forming mold 24, and the upper end of piston 2i engages the abutment at the upper end of cylinder 26. When this occurs, continued operation of the pumps will cause the pressure to build up in the system and when this pressure exceeds pounds per square inch, piston 46 in valve C will move upwardly, unseating valve 46, thereby permitting fluid from the low pressure pump L to bypass to makeup tank T through chamber 38, passage 4i, intermediate chamber 31, and pipe 45. The high pressure pump H, however, will continue to operate until the pressure in the system communicated to motors 66 and 62 is sufllcient to overcome the tension of spring 83. When this occurs sliding block 1| of pump H will be moved to the left (Fig. 2), thereby placing said pump on leakage stroke. Inasmuch as both motors 66 and 62 are now operating against the action of spring 62, the pump H is held on leakage stroke at a materially reduced pressure.

The press 3 is now conditioned for operation and the work may be placed in the forming mold 24. When the press has been so loaded the operator then adjusts valve members H and I2 of valve A by manipulation of lever i8 to the position shown in Fig. 4. Fluid from the annular chamber 26 of cylinder 26 will now enter the lower end of chamber i6 of valve A through pipe 52, and thence flow through passage l6 and pipe 68 to the storage or makeup tank T. The pressure in the system is now reduced and spring 83 urges sliding block H to the right (Fig. 2) placing the pump on stroke. When valve A is adjusted in this manner, it will be noted that motor 62 is disconnected from the pressure in the system and therefore is ineflective.

ll ii Fluid under pressure from pump H now enters the upper end of cylinder 20 through valve A and pipe 50. As a result of the reduction in pressure in the system caused by connecting chamber I to exhaust, as described above spring 42 of valve C will urge valve member 40 upon its seat, thereby closing the bypass, and fluid from the low pressure pump L will also enter the upper end of cylinder 20 through pipes 8 and 5, valve A, and pipe 50. Thus, the combined discharges of pumps H and L are operative upon piston 2|, which moves downwardly at a comparatively high rate of speed. When platen 21 engages the work the pressure in the system again builds up and when this pressure exceeds the tension of spring 42, which, as previously stated, has been set at 150 pounds per square inch, piston 46' w ll again unseat valve 0, thereby causing the fluid discharginl from pump L to bypass to makeup tank T. The high pressure pump, however, continues to operate to compress the work in the mold until the developed pressure exceeds 1000 pounds per square inch, the pressure to which spring 83 is adjusted. When the pressure in the system exceeds this value piston 66 of motor 60 urges sliding block II toward neutral or leakage stroke position and the pressure may thus be maintained upon the work for any desired period of time. Inasmuch as the cross sectional area of piston 23 is greater than that of piston 2|, and due to the connection of cylinder 22 with pipe 50 through p pe 56, valve 13. and pipe 53, the piston 23 will be held in its uppermost position against the pressure exerted upon the work by piston 2|. ter the materials in the mold have been under compression the desired period of time, the operator actuates valve members 30 and 3| of valve B by manipulation of lever 32 to the position shown in Fig. 5. When valve B is so adjusted the fluid in cylinder 22 will bypass to storage tank T through pipe 53, chamber 29 of valve B, and pipe 54. As a result the pressure in the system is again reduced and spring 83 again places pump H on stroke, ca sing flu d under pressure to be discharged throu h pipe and thence to the upper; end of cylinder 20, causing piston 2! to continue its downward movement. When the pressu e decreases to 150 pounds per square inch low pressure pump L will also become effective to assist in this down ward movement of platen 27. Platen 21 continues to move downwardly in this'manner. causing the work formed in the mold to be ejected therefrom, which then may be removed by the operator.

This downwa d movement of piston 2! may continue until it engages the lower end of cylinder 20. when the pressure in the system again builds up. When this pressure exceeds 1000 pounds per square inch, pump H will aga n be placed on neutral or leakage stroke by the fluid motor 60 as hereinbefore described. However, when the work is ejected from the mold, the operator usually moves levers l3 and 32 of valves Aand B respectively to the full line position shown'in Fig. 1 to condition the press for another operation. Pistons 2i and 23 will then be moved to their uppermost positions as previously described, by the combined discharges of pumps H and L. When piston 2| reaches the upper end of cylinder 20, the pressure in the system again builds up. At this time it will be remembered that both of the fluid motors Eli and 62 operate in unison, to adjust the pump to, and maintain the same on leakage stroke position. The pressure required to maintain the pump on leakage stroke, therefore, is materially reduced.

It therefore is seen that a highly efiicient control mechanism has'been provided. By reducing the pressure required to maintain the pump on leakage stroke, the load imposed on the motor M is also reduced, with the result that undue strains on the apparatus are not only minimized, but the cost of operation thereof is greatly reduced. It also is believed to be clear that pump H and the control mechanism associated therewith form a unitary construction which is adaptable for general use.

The invention therefore, it is to be understood, is not to be limited to the embodiment herein shown, since it may be embodied in other forms, all coming within the scope of the claims which follow.

What is claimed is:

1. In a fluid system, the combination with a variable stroke pump, of a fluid motor operated by said pump, means for controlling the operation of said motor including a valve, means for placing said, pump on stroke, means for returning said pump to leakage stroke position, said last mentioned means comprising a pair of servo motors, one of said servo motors being constantly connected to the discharge pressure in the system and adapted to return the pump to leakage stroke position when the pressure in the system exceeds a predetermined value, means for actuating said valve to control the operation of said fluid motor and to connect the second of said servo motors to said discharge pressure whereby said second fluid motor operates in the same direction as said first mentioned servo motor to return the pump to and maintain the same on leakage stroke position at a comparatively low pressure.-

2. In a fluid control system, the combination with a variable stroke pump, of resilient means for placing said pump on stroke, means for actuating said pump to and retaining the same on leakage stroke position, said last mentioned means comprising a pair of fluid motors, one of said motors being constantly connected to the discharge pressure in the system, and a valve for connecting the other of said motors to said discharge pressure, whereby the combined ac tion of said motors maintains said pump on leakage stroke position at a relatively low pressure.

3. In a fluid control system, the combination with a variable stroke pump, of adjustable resilient means for placing said pump on stroke, means for actuating said pump to and retaining the same on leakage stroke position, said last mentioned means comprising a pair of fluid motors, one of said motors being constantly connected to the discharge pressure in the system and adaptable to return said pump to leakage stroke position when the pressure in the system exceeds the tension of said resilient means, a valve for connecting the other of said motors to said discharge pressure, whereby the combined action of said motors maintains the pump on leakage stroke position at a relatively low pressure.

4. In a fluid system, the combination with a variable stroke pump, of a. fluid motor operated by said pump, adjustable resilient means for placing said pump on stroke, means for controlling the operation of said fluid motor including a valve, means for returning said pump to leakage stroke position, said last mentioned means comprising a pair of servo motors, one of said servo motors being constantly connected to the discharge pressure in the system and adapted to return the 5. In a fluid control system, the combination' with a high pressure pump and a low pressure pump, resilient means for placing said high pressure pump on stroke, automatic bypass means for rendering said low pressure pump ineflective when the pressure in the system exceeds a predetermined value, and a plurality of means for returning said high pressure pump to leakage stroke position, one of said means being adapted to maintain said high pressure pump on leakage stroke position at a comparatively high pressure, and means for conditioning another of said last mentioned means for operation, whereby said high pressure pump is maintained on leakage stroke position at a comparatively low pressure by the combined action of said pump actuating means.

6. In a fluid control system, the combination with a high pressure pump and a low pressure pump, adjustable resilient means for placing said high pressure pump on stroke, automatic bypass means for rendering said low pressure pump ineflective when the pressure in the system exceeds a predetermined value, and a plurality of fluid motors for returning said high pressure pump to leakage stroke position, one of said motors being adapted to maintain said high pressure pump in neutral position at a comparatively high pressure, and valve means for conditioning another of said fluid motors for operation where by said high pressure pump is maintained on leakage stroke position at a comparatively low pressure by the combined action of said fluid motors.

'7. In a fluid system, the combination with a fluid motor comprising a pair of cylinders, a pressing piston operative in one of said cylinders and a holding piston operative in the other of said cylinders, said pistons being adapted for relative movement, of a pump for actuating said pistons, means for placing said pump on discharge stroke, hydraulic connections between said pump and said cylinders, a pair of valves for controlling the sequence of operation of said pistons, said valve when adjusted to one position causing both of said pistons to move simultaneously in one direction, means for actuating said pump toward leakage stroke position and retaining the same in said position when said pistons reach the limit of their travel in said direction, means for adjusting one of said valves to another of its positions of adjustment causing said pressing piston to move toward said holding piston while retaining the latter against movement, and means for actuating the other of said valves to another of its positions of adjustment, whereby said holding piston will move in the same direction as said pressing piston moves in its last mentioned movement.

8. In a fluid system, the combination with a fluid motor comprising a pair of cylinders, a pressing piston operative in one of said cylinders, and a holding piston operative in the other of said cylinders, said pistons being adapted for relative movement, of a pump for actuating said pistons, means for placing said pump on discharge stroke, valve means for controlling the sequence of operation of said pistons, said valves when adjusted to one position causing said pressing piston to move toward said holding piston while retaining the latter in holding position, means for actuating said pump toward leakage stroke position and retaining the same in said position at a relatively high pressure, means for actuatingsaid valve means to another position of adjustment causing said pressing piston to move away from said holding piston, and additional means operative in conjunction with said pump actuating means for actuating said pump toward leakage stroke position when said pressing piston reaches the limit of its travel away from said holding piston, whereby said pump is held on leakage stroke at a reduced pressure.

9. In a fluid system, the combination with a fluid motor, comprising a pair of cylinders, a pressing piston operative in one of said cylinders and a holding piston operative in the other of said cylinders, said pistons being adapted for relative movement, of means for operating said pistons including a high pressure pump and a low pressure pump, automatic means for rendering said low pressure pump ineifective when the pressure delivered to said pistons exceeds a predetermined value, adjustable resilient means for maintaining said high pressure pump on stroke,

a plurality of servo motors for returning said high pressure pump to leakage stroke position under predetermined conditions, one of said servo motors being constantly connected to the discharge pressure in said system, a plurality of valves for controlling the sequence of operation of said pistons, said valves when operated to one position causing said pistons to move simultaneously in one direction by the combined dis-- charges of said pumps, and at the same time connecting the other oi! said servo motors to said discharge pressure, whereby, when said pistons reach the limit of their travel in said direction the pressure developed in said system first actuates said automatic means to render said low pressure pump ineffective, and at a higher predetermined pressure said high pressure pump is rendered ineffective by the combined action of said servo motors, means for actuating one of said valves to another of its positions of adjustment, thereby causing said pressing piston to move toward said holding piston, while retaining the latter against movement, and at the same time disconnecting one of said servo motors whereby said pump is actuated toward leakage stroke position at a still higher predetermined pressure, and means for actuating another of said valves to another position of adjustment, whereby said holding piston moves in the same direction as said pressing piston.

HENRY W. LANDENBERGER.

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