US2424300A - Control system for hydraulic circuits - Google Patents

Control system for hydraulic circuits Download PDF

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Publication number
US2424300A
US2424300A US470268A US47026842A US2424300A US 2424300 A US2424300 A US 2424300A US 470268 A US470268 A US 470268A US 47026842 A US47026842 A US 47026842A US 2424300 A US2424300 A US 2424300A
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United States
Prior art keywords
pump
servomotor
plunger
fluid
conduit
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US470268A
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English (en)
Inventor
Becker Walter
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Hydraulic Development Corp Inc
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Hydraulic Development Corp Inc
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Publication date
Priority to BE469620D priority Critical patent/BE469620A/xx
Application filed by Hydraulic Development Corp Inc filed Critical Hydraulic Development Corp Inc
Priority to US470268A priority patent/US2424300A/en
Priority to US510891A priority patent/US2417858A/en
Priority to GB1913/44A priority patent/GB574475A/en
Priority to FR938596D priority patent/FR938596A/fr
Application granted granted Critical
Publication of US2424300A publication Critical patent/US2424300A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/16—Control arrangements for fluid-driven presses
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20546—Type of pump variable capacity
    • F15B2211/20553—Type of pump variable capacity with pilot circuit, e.g. for controlling a swash plate
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30505—Non-return valves, i.e. check valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50554—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure downstream of the pressure control means, e.g. pressure reducing valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5153—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve
    • F15B2211/5154—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve being connected to multiple ports of an output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/555—Pressure control for assuring a minimum pressure, e.g. by using a back pressure valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/565—Control of a downstream pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/635—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements
    • F15B2211/6355—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements having valve means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/665—Methods of control using electronic components
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/665—Methods of control using electronic components
    • F15B2211/6651—Control of the prime mover, e.g. control of the output torque or rotational speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7053—Double-acting output members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/75—Control of speed of the output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/76—Control of force or torque of the output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/775—Combined control, e.g. control of speed and force for providing a high speed approach stroke with low force followed by a low speed working stroke with high force, e.g. for a hydraulic press

Definitions

  • This invention relates to control systems, and, in particular, to control systems for hydraulic circuits.
  • the flow controlling means operated by the linkage inter connected with the platen is shifted to direct iiuid to the retraction area of the press. If the fluid is supplied by, say, a variable delivery pump,
  • the pump will start under load due to the settling of the ram.
  • the prime moverfor driving the pump will also be started under load. and, in the case of an electric motor as the prime mover, expensive and complicated starting devices are required in order not to overload the power lines supplying energy to the driving motor.
  • Figure 1 diagrammatically illustrates the control system according to the invention in connection with a hydraulic press circuit
  • Figure 2 is a wiring diagram for the system of Figure l.
  • control Vsystem com-prises a variable delivery pump including 'centering springs continuously urging the pump toward neutral, while servomotor means is connected with the pump for selectively shifting the pump into forward or retraction stroke delivery position.
  • T-he servomotor means includes a valve mem- 0 vents the supply of actuating fluid to the plunger ing the pump may vbe started under no load conditions, regardless of the position occupied by the. press ram. f
  • It is still another object of the invention provide a control system for use in connection with hydraulic systems, which includes a variable delivery pump drivingly connected with a prime mover, and pilot fluid operated servomotor means for controlling the delivery of said pump, and in which, responsive to the starting of said prime mover, the pilot uid from said servomotor means is by-passed to an exhaust until said prime mover has reached a predetermined minimum speed.
  • the servomotor means for a predetermined time following the starting of the prime mover. After the said predetermined time the fluid supply for the plunger is re-established to actuate said plunger for shifting the pump on stroke.
  • the press ram controlled by the delivery of the pump, is then returned to its initialposition. In this way, the prime mover is prevented from starting under load, thereby protecting said prime mover 0 and reducing the power for actuating the same.
  • the control system according to the invention is also provided with safety means which prevents the operator from accidentally starting a working stroke of the press ram before the prime mover has come up to speed.
  • the electric circuit for controlling the operation.of the ram and the driving motor for the pump which includes 'a starter button for starting the motor or prime mover and a forward lbutton for starting the working stroke of the ram, is so arranged that closing of the forward button is not effective until after energzation of the motor and the elapse of the above mentioned predetermined time.
  • the structure disclosed therein comprises a press cylv inder I having reciprocably mounted therein a press ram 2, which has connected thereto a press platen 3.
  • the platen 3 is provided with an arm 4 adapted t0 engage a collar 5 adjustably mounted on a push rod 6, which is reciprocably mounted and guided by any convenient guiding means.
  • a collar 5a adapted to engage the arm Ia on the press cylinder I, to thereby limit the downward movement of the push rod 6.
  • a collar 1 adapted to engage the arm 8 of a three-arm lever, generally designated 9.
  • a second arm of the lever 9 is pivotally connected with a link I0 which, in its turn, is connected to an armature I I adapted to be actuated by the main solenoid I2 in such a manner as to cause the armature II to move downwardly, thereby shifting the three-arm lever 9 in clockwise direction about the pivot I3.
  • the third arm of the lever 9 is connected through a link system, vgenerally designated I4, with a control rod I5, which has connected thereto a ange I6 an a valve member I1.
  • the valve member I1 is reciprocably mounted in a servomotor plunger I8 which, in its turn, is reciprocably mounted in the servomotor casing I9 connected, in any convenient manner, with the pump 20, constituting a pump of reversible variable delivery.
  • the pump 20 may be of any standard design, for instance of the radial piston type or the radial vane type.
  • the servomotor plunger I8 has a larger piston portion 2
  • the smaller portion 23 of the plunger I8 is provided with an annular groove 25 which communicates through longitudinal passageways 26 with the left side of the piston portion 2l,
  • the said left side of .-he piston portion 2I constitutes the larger eective area thereof, while the oppositely located area of the piston portion 2
  • the valve member I1 controls the bores 21 and the annular groove 25.
  • the bore 28 is furthermore adapted to communicate with the bore 24 through the passageways 29.
  • the right hand end of the bore 22 is connected with a. conduit 30 comprising an adjustable choke 3I and leading to a control valve, generally designated 32.
  • the choke 3I is adapted to be by-passed by fluid passing from the valve 32 toward the servomotor casing I9 through the conduit 33 and check valve 34 in said conduit.
  • Branching oif from the conduit 38 is a conduit 35 comprising a check valve 36 and leading to the left hand end of the bore 22. 4
  • the bore 24 in the servomotor casing I9 is furthermore connected through a conduit31 with a fluid reservoir or tank 38.
  • Reclprocably mounted in the casing 4 I is a valve member 42 with piston portions 43 and 44 and an armature 45 adapted to be controlled by the solenoid SI.
  • valve member 42 is continuously urged, by means of a spring 46, into its left hand position, shown in the drawing, in which the conduit 38 communicates with the conduit 41 which is connected to the pressure side of a pilot pump 48.
  • pilot pump'48 which may be of any standard design, and may be a variable delivery or a' constant delivery pump, has its suction side connected through the conduit 49 with the tank 38.
  • conduit 60 Branching off from the conduit 41 is a conduit 60 comprising an adjustable pressure relief valve 5I and leading to the tank 38.
  • valve member 42 moves into its right hand end position, in which the conduit 41 communicates with the conduit 39, while the conduit communicates with the conduit 48.
  • 'I'he servomotor plunger I8 has furthermore arranged therein a spring 52, which continuously urges the valve member I1 to move toward the left with regard to the casing I8.
  • 'I'he pump 26 has furthermore connected thereto a casing 53 housing centering springs 54 and 55, which act upon a control rod 56 connected to the ilow control member of the pump 20, so as to urge the -pump 20 into and tend to hold the same in its neutral or no delivery position.
  • One side of the pump 28 is connected through a conduit 51 with the upper portion of the press cylinder I,'while the lower portion of the press cylinder I is connected through conduit 58 with the other side of the pump 28.
  • aiconduit 59 Also connected with the upper portlonof the press cylinder I is aiconduit 59 leading to a tonnage control valve 60, which latter is connected, through the conduit 6I, with the tank 38.
  • The' tonnage control 'valve 60 which may be of any standard design,
  • asurge valve 62 Extending into the upper portion of the press cylinder I is asurge valve 62, of any conventional design, for instance of the type disclosed in U. S. Patent No. 2,193,248, and adapted, in response to a suctio'n eifect in the upper portion of the press cylinder I, to open so as to eiect fluid connection between the tank 38 and the upper portion of the cylinder I.
  • the surge valve 62 closes.
  • the surge valve 62 is connectedwith a pilot line 63 communicating with the conduit 58.
  • the surge valve 82 is adapted, in response to a predetermined pressure in the pilot line 63, to open for establishing fluid connection between the tank 38 and the upper portion of the press cylinder I.
  • Branching oi! from the conduit 63 is a conduit 64 comprising a check valve 65 adapted to allow the ow of fluid from the tank 38 into the conduit 64, while preventing the ilow of iluid in the opposite direction.
  • the pump 20 is directly driven by a motor 11 while the pilot pump 4I is likewise directly driven by a second motor 18.
  • the motors 18 and 11 are permanently connected in parallel and operate in unison. Both pumps could, therefore, be
  • the main supply line 86 has connected thereto the line 81, which is adapted to be electrically connected with the line 68 by closure of the line switch 69.
  • the line 68 is connected through the normally closed stop switch 18 with the line 1i, which latter is adapted, by closure of the forward switch 12, to be connected with the line 13.
  • the line 13 is connected through the normally closed switch Rid with the line 14, comprising the main solenoid i2 and connected to the main supply line 15.
  • Also connected to the Amain supply line' 15 is the line 18 leading to one terminal of the main motor 11, while the other terminal of the motor 11 is connected to the line 18.
  • the main motor 11 has its driving shaft connected to the shaft of the pump 20 so that rotation of the motor 11 causes rotation of the pump 20.
  • the driving shaft of motor 11 is connected to the shaft of pump .'iil by a flexible coupling.
  • an auxiliary or pilct'pump motor 18 Arranged parallel to the motor 11 is an auxiliary or pilct'pump motor 18, having one terminal connected through line 80 with the line 18, while the other terminal is connected through line 8i with the main supply line 15.
  • the motor 19 has its driving shaft connected with the shaft of the pilot pump 48 so that rotation of the pilot motor 18 causes operation of the pump 88.
  • Theline 18 is connected with a line 82 comprising the contactor solenoid R2, and having one end connected to the main supply line 15, while the other end leads to a terminal of a normally open contactor blade Rib which, in closed position, connects the line 82 with the line 83.
  • the line 83 is connected with the line 1i and communicates through the normally closed tonnage control switch 88a. with the normally open main solenoid switch i2a. When the switch i2a is closed, the tonnage control switch 60a is connected through the normally closed reverse button 84 with the line 85, which latter is connected with the line 134
  • the line 83 is also adapted to be connected with the line 82 by closure of the contactor switch R2a.
  • a line 88 adapted, by closure of the starter button 81, to electrically communicate with the line 88, which latter communicates with the line 89 through the normally' closed timer switch Ti.
  • the line 88 includes a contactor Ri and is connected with the main supply line 15. Also connected to the main supply line is one terminal of a timer T, the other terminal of which is connected to the line 89. Closure of the contactor switch Ria is adapted to eiect connection between the line 83 and the line 88.
  • a line 90 adapted, by closure of the contactor switch Ric, to be connected with the line 9i, which latter comprises the solenoid Si, and is connected with the main supply line 15.
  • Branching off from the line 9i is a line 92 adapted, by closure of the limit switch 83, to be connected with the line 83.
  • the limit switch 93 is normally held in open position and is closed by engagement of the roller 94 (Fig. 1) with the cam 85 carried by the press platen 3.
  • the operator closes the line switch 89 and furthermore closes the starter button 81.
  • the energizing circuit for the contactor Ri ands the timer T is closed, which circuit comprises the main supply line 66, switches 69 and 18, line 83, now'closed starter button 81, lines 88 and 89, contactor Ri and timer T, and the main supply line 15.
  • Energization of the contactor Ri causes closure of the contactor switches Ria, Rib and Ric, while causing the contactor switch Rid to open. Opening o f the contactor switch Rid has no effect at this time.
  • Closure of the contactor switch Ria establishes a holding circuit for the contactor Ri and the timer T so that the contactor Ri and the timer T will remain energized when the starter button 81 is released and thereby returns to its open position.
  • the said holding circuit comprises the main supply line 66, switches 89 and 10, line 83, contactor switch Ria, lines 88 and 89, contactor Ri and timer T and the main supply line 15.
  • the timer T is now operating for a predetermined time for which it has been set. This predetermined time corresponds to a period necessary to bring the main motor 11 up to a desired speed. After this said predetermined time has expired, the timer switch Ti opens temporarily to thereby stop the timer T, and immediately thereafter the timer switch Ti again closes.
  • the contactor switch Ric closes, the energizing circuit for the solenoid Si is closed, which energizing vcircuit comprises the main supply line 66, lines 61, 88, 1i, 83 and 98, the now closed contactor switch Ric, line 9i, solenoid Si and main supply line 15.
  • Energization of the solenoid Si causes the valve member 42 to move toward the right against the thrust of the spring 48, thereby establishing fluid connection between the conduits 39 and 41, while simultaneously connecting the conduit 30 with the conduit 48.
  • the contactor switch Rib closes, the energizing circuit for the contactor R2 is closed, which energizing circuit comprises the main supply line 66, lines 61, 88, 1i and 83, the now closed contactor switch Rib, line 82, contactor R2 and the main supply line 15. Energization of the contactor R2 causes closure of the contactor switch R2a, thereby establishing a holding circuit for the contactor R2, which maintains the latter energized When the contactor switch Rib opens.
  • the timer switch TI opens temporarily, thereby breaking the holding circuit for the contactor RI and the timer T. This causes deenergization of the timer T and the contactor RI and, as a result thereof, the contactor switches Rla, RIb and Rlc open, whereas the contactor switch RId closes. the timer switch TI then again closes, it will not re-establish theenergizing circuit for the contactor RI and the timer T.
  • Opening of the contactor switch RIc causes deenergization of the solenoid SI, so that the spring 46 returns the valvemember 42 to the position shown in Figure- 1, in which fluid connection is established between the conduits 41 and 38, while the fluid connection between the conduits 41 and 38 is interrupted. Therefore,.the fluid delivered by the pump 48 now passes through the conduit 41, valve 32, conduit 33, check valve 34 and conduit 38 into the bore 22, where it acts upon the smalleror right hand area of the piston portion 2 I. This causes the plunger I8 to move toward the left, thereby placing the pump28 on retraction stroke. The iluid expelled during the leftward movement of the plunger I8 from the left hand side ofthe bore 22 passes through the passageways 26, bore 28, passageways 28 and conduit 31 into the tank 38. The pump 28 now delivers pressure fluid through the conduit 58 into the lower Iportion of the press cyl.. inder I and causes the ram 2 to move upwardly.
  • the operator closes the forward switch 12, thereby clos- ⁇ 41, 33 and 38 and the bores 21 and 28 and causes the plunger I8 to move toward the right against the thrust of the centering springs 54 and 85.
  • the pump 28 is placed on forward stroke, and now delivers fluid through the conduit 51 into the upper portion of the press cylinder 'I, while withdrawing fluid through the conduit 58 from the lower portion of the press cylinder I.
  • the press ram 2 now moves downwardly by gravity as fast as iluid is withdrawn from the lower portion of the cylinder I.
  • the suction effect created in the upper portion oi.' the cylinder I maintains the surge valve 82 open, so that the 'iiuid delivered by the pump 28 into the upper portion of the cylinder I is supplemented by fluid passing from the tank 38 through the surge valve 82 into the cylinder I.
  • the cam 85 engages the roller 84 and closes the switch 83.
  • Closure of the'switch 83 establishes a by-pass circuit for the now open contactor switch RIc, thereby closing the energizing circuit for the solenoid SI.
  • Energization of the solenoid SI causes the valve member 42 to move toward the right, thereby again effecting fluid connection between the conduits 41 and 38, while connecting the conduits 38 and 48 with each other. Since now fluid' may escape from the left hand portion of the bore 22 through the conduit 35, check valve 38, conduit 38, choke 3
  • Pressure uid delivered by the pump 48 now ⁇ amanece again shifts the plunger la toward the right in the manner described previously, thereby returning the pump to its full delivery forward Astroke position.
  • the ram 2 now performs its actual pressing stroke.
  • the fluid delivered by the pump 48 into the conduit 30 now acts upon the smaller effective areaof the piston portion 2
  • the pump 20 is now in its retraction stroke position, in which it delivers pressure fluid through conduit 58 into the lower portion of the press cylinder I, and causes the ram 2 to move upwardly, while the fluid expelled from the upper portion of the cylinder I passes, in part, through the conduit 51 vto the now suction side' of the pump 28 and, in part, into the tank 38 through the surge valve 82 which, as previously explained, has been opened by pressure fluid conveyed from the conduit 58 through the pilot line 63 to the surge' valve 62.
  • the ram 2 now performs its upward movement or retraction stroke in the man-y ner set forth above in connection with vthe description of the conditioning of thepress for a working cycle after a period of idleness.
  • the pilot pump'4'8 may be replaced by an accumulator, in which instance the conduit 39 and the motor 19 with the lines 80 and 8
  • and switch93 may be omitted.
  • and directly communicating with the conduit will either be omitted or plugged , without affecting the control system of the present invention for preventing the starting of the pump motor 'I1 under load.
  • a double-acting plunger a fluid source of reversible delivery for supplying actuating iluid to said plunger, a prime mover drivingly connected to said source, yielding means normally urging said source toward neutral, a fluid operable servomotor normally positioning said source to deliver to said plunger in one direction, control means energlzable to move said servomotor to position said source to deliver to said plunger in the other direction, means operated by said plunger in a predeterminedposition of movement thereof in said one direction for actuating said servomotor for moving said fluid source into no delivery position, and
  • a vertically reciprocable plunger a pump of reversible delivery connected te supplsr said plunger, meanscontinuously urging said pump toward neutral, a prime mover directly connected with said pump.
  • a fluid operable servomotor associated with said pump normally urging the same to deliver to said plunger to move the same upwardlyand adapted for actuation by said plunger in a predetermined' upper position thereof for moving said pump to neutral
  • control means energizable to actuate said servomotor to move said pump to deliver to said plunger to move the same downwardly
  • a source of nuid for supplying said servomotor
  • means ⁇ operable automatically in response to the starting of said prime mover forinterrupting the supply of :duid to said servomotor while simultaneously exhausting said servomotor and for interrupting the energizing circuit for said control means, said automatically operable means being effective for a predetermined length ofvtime during which said prime mover comes up to speed, and other means operated
  • a vertically reciprocable double-acting plunger for supplying fluid to said plunger, yielding means normally urging said pump toward neutral, a iiuid operable servomotor associated with said pump normally urging the same to deliverto the underneath side'of said plunger and adapted for actuation by said plunger in a predetermined upper position thereof for moving said pump to neutral, first electrical means energizable to move said servomotor to position said pump to deliver to the upper side of said plunger,
  • ⁇ fluid operable advancing and retracting means reversing the delivery thereof to selectively supply pressure iluid to said advancing and retracting means
  • an auxiliary fluid source for supplying actuating fluid to said servomotor means to move said pump into delivery position in either of two directions to control the direction of flow therefrom, centering means continuously urging said pump into and tending to hold the same in substantially neutral or no delivery position, means operated by said plunger at least in one position thereof to actuate said servomotor for moving, and holding said pump in neutral position as long as said plunger is in said one position, electric motor means drivingly connected with said pump, starter means for initiating operation of said motor means, control means for actuatingsaid servomotor means to move said pump into delivery 'position to supply pressure iluidstosaid advancing means, and electrically actuated means operatively connected with said startenlmeans and said control means and responsiveltgjlhe actuation of said starter means and operab ffor a predetermined length of time to pre
  • a reciprocable plunger having iluid'operable advancing and retracting means, a pump of reversible delivery for supplylng actuating fluid to said means, iiuid operable servomotor.
  • means for positioning said pu'mp to deliver ln either direction means for supplying actuating iiuid to said servomotor including valve means movable to exhaust said servomotor, centering means continuously urging said pump toward neutral position, means operated by said 50 plunger at least in one position thereof to actuate said servomotor for moving and holding said pump in neutral position as long as said plunger is in said one position, a prime mover drivingly of said plunger to hold said servomotor in neutral position until said prime mover reaches a predetermined minimum speed, and other means operable by said plunger during the movement thereof for momentarily actuating said an auxiliary fluid source for supplying actuating valve means to exhaust said servomotor.
  • a reciprocable plunger having fluid operable advancing and retracting means, a pump of reversible delivery for supplying actuating uid to said means, iluid operable servomotor means associated with said pump for determining the direction of delivery thereof, means for supplying actuating fluid to said servomotor including valve means actuatable to exhaust said servomotor, centering means continuously urging said pump toward neutral position, control means selectively operable to actuate said servomotor to move said pump todeliver to said advancing area, means operated by said plunger in its retracting direction of movement to actuate said servomotor for moving said pump toward neutral position, a prime mover drivingly connected with said pump, starter means for energizing said prime mover, and means interlockingr said starter means and said control means and operable for a predetermined time after the actuation of said starter means to initiate movement of said prime mover to prevent actuation of said control means, during which time said prime mover reaches a
  • a reciprocable plunger having fluid operable advancing and retracting means, a pump of reversible variable delivery for supplying pressure fluid selectively to said advancing or said retracting means, fluid operable servomotor means associated with said pump for reversing the delivery thereof to selectively supply pressure uid to ⁇ said advancing and retracting means, an auxiliary uid source for supplying actuating fluid to said servomotor, centering means continuously urging said pump into and tending to hold the same in substantially neutral or no delivery position, means operated by said plunger at least in one position thereof to actuate said servomotor for moving and holding said pump in neutral position as long as said plunger is in said one position, an electric motor drivingly connected-to the drive shaft of said pump for positively driving the same, starter means for starting operation of said electric motor, electrically operable control means operable in response to the operation of the said starter means and eiective for a predetermined length of time for preventing delivery of iluid to said serv
  • a control system for a hydraulic pu'mp which is drivingly connected to a prime mover to prevent the pump from being placed on a delivery stroke before the prime mover has reached a predetermined minimum speed that includes in combinatiom servomotor means operably connected to the pump to place the same on a delivery stroke in either direction or in neutral, yielding means normally urging said pump into neutrai position, control means operably connected to said servomotor having on position for placing said servomotor in position to place said pump on delivery stroke in one direction and a second position to place said servomotor in position to place said pump on delivery stroke in the other direction, means for supplying iluid to said servomotor for actuating the same in response to movements of said control means, and other means operable automatically upon initiation of movement of said prime mover for preventing the supply of :duid to said servomotor thereby to permit said yielding means to position said pump in neutral and to render said control means ineffective to change the position of said servomotor, said other means being oper
  • a control system for a hydraulic pump that is directly connected to a prime mover to prevent the pump from being placed on a delivery stroke before the prime mover has reached a predetermined minimum speed that includes in combination, a pump of variable delivery, a prime mover directly connected to the pump for driving the same servomotor means operably connected to the pump to place the same on a delivery stroke or on neutral, means normally urging said pump into neutral position, control means operably connected to said servomotor having one position for placing said servomotor in position to place said pump on a delivery stroke and a second position to place said servomptor in position to place said pump on neutral stroke, electrically operated means for preventing delivery of actuating iiuid to said servomotor, means for energizing said prime mover to start said pump and including means to operate said electrically actuated means to prevent delivery of actuating uid to said servomotor whereby to prevent said servomotor from changing the position of said pump from neutral position as retained therein by the
  • a iluid operable motor a pump of variable delivery for supplying fluid to said motor, means continuously urging said pump toward neutral, iiuid operable servomotor means for moving said pump to delivery position, a prime mover directly connected with said pump, an auxiliary source of pressure uid for supplying said servomotor, valve means connecting said auxiliary source with said servomotor, means responsive to the starting of said prime mover for actuating said valve to prevent the supply of iluid from said auxiliary source of said servomotor', said means being eiective during a predetermined period of time to allow said prime mover to come up to speed under no load, means operable in response to a predetermined movesaid pump toward neutral, fluidoperable servomotor means for moving said pump to delivery position, a prime mover directly connected with said pump, an auxiliary source of pressure iluid for supplying said servomotor, valve means connecting said auxiliary source with said servomotor, means responsive to the starting
  • said motor for actuating said valve ⁇ means to interrupt the supply of ,fluid to said servomotor while exhausting the same, ilow restricting means connected to control the rate Aoi' exhaust from said servomotor; and means responsive to a predetermined further movement oi' said motor for again bringing about the supply oi' actuating fluid from said auxiliary source to said servomotor.
  • said power means for rendering said valve actuating means for a predetermined time after the starting oi the power means to actuate said valve means for disconnecting said control means trom said source and for connecting it instead with exhaust, means permitting free supply of fluid from said valve to said control means and a restricted exhaust o! uid from said control means, and other means selectively operable for energizing said valve actuating means irrespective of whether or not said prime mover is being started.
  • a iluid source for supplying actuating fluid to said plunger, means normally urging said source into neutral position for preventing the delivery of tluidto or the removal of iluid from said plunger, control means REFEBENCES CITED

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Press Drives And Press Lines (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
US470268A 1942-12-26 1942-12-26 Control system for hydraulic circuits Expired - Lifetime US2424300A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
BE469620D BE469620A (enrdf_load_stackoverflow) 1942-12-26
US470268A US2424300A (en) 1942-12-26 1942-12-26 Control system for hydraulic circuits
US510891A US2417858A (en) 1942-12-26 1943-11-19 Control system for hydraulic presses
GB1913/44A GB574475A (en) 1942-12-26 1944-02-02 Hydraulic system
FR938596D FR938596A (fr) 1942-12-26 1946-08-30 Perfectionnements apportés aux dispositifs de commande, notamment à céux pour des installations électriques

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US470268A US2424300A (en) 1942-12-26 1942-12-26 Control system for hydraulic circuits

Publications (1)

Publication Number Publication Date
US2424300A true US2424300A (en) 1947-07-22

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Application Number Title Priority Date Filing Date
US470268A Expired - Lifetime US2424300A (en) 1942-12-26 1942-12-26 Control system for hydraulic circuits

Country Status (4)

Country Link
US (1) US2424300A (enrdf_load_stackoverflow)
BE (1) BE469620A (enrdf_load_stackoverflow)
FR (1) FR938596A (enrdf_load_stackoverflow)
GB (1) GB574475A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2571758A (en) * 1946-03-23 1951-10-16 Hpm Dev Corp Fluid operable device
US2639585A (en) * 1951-12-15 1953-05-26 Florence Pipe Foundry And Mach Hydraulic press cycle control system
US4391571A (en) * 1978-10-14 1983-07-05 Craggs Thomas Arthur Pumping apparatus for pumping liquids such as slurrys

Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US473949A (en) * 1892-05-03 Mechanism for raising water
US823118A (en) * 1904-06-20 1906-06-12 Howard F Gurney Electrically-driven pump.
US1847229A (en) * 1930-04-05 1932-03-01 Electric Machinery Mfg Co Compressor unloader
US1911105A (en) * 1930-11-14 1933-05-23 Frick Co Unloader for compressors
US1910000A (en) * 1932-02-29 1933-05-23 Frick Co Unloader for compressors
US2145404A (en) * 1937-08-13 1939-01-31 Webster Electric Co Inc Fuel supply unit for oil burners
US2167623A (en) * 1936-08-15 1939-08-01 George H Britter Fluid operated pump jack
US2184665A (en) * 1937-10-21 1939-12-26 Hydraulic Press Corp Inc Self-centering servomotor
US2260175A (en) * 1940-01-23 1941-10-21 Hydraulic Dev Corp Inc Press with electrically controlled collapsible air link
US2280291A (en) * 1939-04-10 1942-04-21 Rotary Lift Company Power transmitting system
US2286358A (en) * 1940-02-02 1942-06-16 Hydraulic Dev Corp Inc Hydraulic control for variable delivery pumps
US2302922A (en) * 1940-01-04 1942-11-24 Hydraulic Dev Corp Inc Variable delivery pilot pump control system

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US473949A (en) * 1892-05-03 Mechanism for raising water
US823118A (en) * 1904-06-20 1906-06-12 Howard F Gurney Electrically-driven pump.
US1847229A (en) * 1930-04-05 1932-03-01 Electric Machinery Mfg Co Compressor unloader
US1911105A (en) * 1930-11-14 1933-05-23 Frick Co Unloader for compressors
US1910000A (en) * 1932-02-29 1933-05-23 Frick Co Unloader for compressors
US2167623A (en) * 1936-08-15 1939-08-01 George H Britter Fluid operated pump jack
US2145404A (en) * 1937-08-13 1939-01-31 Webster Electric Co Inc Fuel supply unit for oil burners
US2184665A (en) * 1937-10-21 1939-12-26 Hydraulic Press Corp Inc Self-centering servomotor
US2280291A (en) * 1939-04-10 1942-04-21 Rotary Lift Company Power transmitting system
US2302922A (en) * 1940-01-04 1942-11-24 Hydraulic Dev Corp Inc Variable delivery pilot pump control system
US2260175A (en) * 1940-01-23 1941-10-21 Hydraulic Dev Corp Inc Press with electrically controlled collapsible air link
US2286358A (en) * 1940-02-02 1942-06-16 Hydraulic Dev Corp Inc Hydraulic control for variable delivery pumps

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2571758A (en) * 1946-03-23 1951-10-16 Hpm Dev Corp Fluid operable device
US2639585A (en) * 1951-12-15 1953-05-26 Florence Pipe Foundry And Mach Hydraulic press cycle control system
US4391571A (en) * 1978-10-14 1983-07-05 Craggs Thomas Arthur Pumping apparatus for pumping liquids such as slurrys

Also Published As

Publication number Publication date
BE469620A (enrdf_load_stackoverflow)
FR938596A (fr) 1948-10-19
GB574475A (en) 1946-01-07

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