US3604313A - Hydraulic power circuit with rapid lowering provisions - Google Patents

Hydraulic power circuit with rapid lowering provisions Download PDF

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Publication number
US3604313A
US3604313A US37114A US3604313DA US3604313A US 3604313 A US3604313 A US 3604313A US 37114 A US37114 A US 37114A US 3604313D A US3604313D A US 3604313DA US 3604313 A US3604313 A US 3604313A
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Prior art keywords
pressure
motor
valve
directional control
control valve
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US37114A
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Waldo G Fruehauf
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ICM ACQUISITIONS Inc A DE CORP
Hydreco Inc
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General Signal Corp
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Assigned to CONTINENTAL ILLINOIS NATIONAL BANK AND TRUST COMPANY OF CHICAGO reassignment CONTINENTAL ILLINOIS NATIONAL BANK AND TRUST COMPANY OF CHICAGO SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ICM ACQUISITIONS, INC., A CORP. OF DE
Assigned to ICM ACQUISITIONS, INC., A DE. CORP. reassignment ICM ACQUISITIONS, INC., A DE. CORP. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: GENERAL SIGNAL CORPORATION, A NY CORP.
Assigned to HYDRECO, INC. reassignment HYDRECO, INC. CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). EFFECTIVE DATE: SEPTEMBER 11, 1987 Assignors: ICM ACQUISTIONS INC.
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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2203—Arrangements for controlling the attitude of actuators, e.g. speed, floating function
    • 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
    • F15B11/024—Systems essentially incorporating special features for controlling the speed or actuating force of an output member by means of differential connection of the servomotor lines, e.g. regenerative circuits
    • 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
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/021—Valves for interconnecting the fluid chambers of an actuator
    • 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
    • F15B11/024—Systems essentially incorporating special features for controlling the speed or actuating force of an output member by means of differential connection of the servomotor lines, e.g. regenerative circuits
    • F15B2011/0243—Systems essentially incorporating special features for controlling the speed or actuating force of an output member by means of differential connection of the servomotor lines, e.g. regenerative circuits the regenerative circuit being activated or deactivated automatically
    • 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
    • F15B2211/20507—Type of prime mover
    • F15B2211/20523—Internal combustion engine
    • 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
    • F15B2211/20576—Systems with pumps with multiple pumps
    • 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
    • F15B2211/3052—Shuttle 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
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30525—Directional control valves, e.g. 4/3-directional control 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
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/3056—Assemblies of multiple valves
    • F15B2211/30565—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve
    • F15B2211/3058—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve having additional valves for interconnecting the fluid chambers of a double-acting actuator, e.g. for regeneration mode or for floating mode
    • 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
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3105—Neutral or centre positions
    • F15B2211/3116—Neutral or centre positions the pump port being open in the centre position, e.g. so-called open centre
    • 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
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3122—Special positions other than the pump port being connected to working ports or the working ports being connected to the return line
    • F15B2211/3127—Floating position connecting the working ports and the return line
    • 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
    • F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
    • F15B2211/3157—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line
    • F15B2211/31588—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line having a single pressure source and multiple 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
    • F15B2211/30—Directional control
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/329—Directional control characterised by the type of actuation actuated by fluid 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
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F15B2211/7107—Multiple output members, e.g. multiple hydraulic motors or cylinders the output members being mechanically linked
    • 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
    • F15B2211/80—Other types of control related to particular problems or conditions
    • F15B2211/86—Control during or prevention of abnormal conditions
    • F15B2211/8609—Control during or prevention of abnormal conditions the abnormal condition being cavitation

Definitions

  • the circuit is characterized by an actuating scheme for the bypass valve which opens that valve only when the directional control valve is shifted to float position and the load pressure in the contracting ends of the cylinders is below a preselected value.
  • the directional control valve may be shifted by pilot pressures, and in this case the motive force for opening the bypass valve may be developed by the pressure in the pilot circuit.
  • FIG.2
  • the cylinders are controlled by a directional control valve which affords the following positions: a neutral" or hold position in which the cylinders are hydraulically locked, a raise position in which the head and rod ends of the cylinders are connected with a supply pump and tank, respectively, a power down position in which the connections between the cylinders and the pump and tank are reversed, and a float" position in which the rod and head ends of the cylinders are interconnected through a regeneration path which is provided with a restricted bleed connection through which the oil displaced by the cylinder rods can escape to the tank.
  • the power down position is used for digging, whereas the float position is used to effect rapid dropping of an empty bucket from an elevated position.
  • the object of the present invention is to provide an improved power circuit including a quick drop bypass valve which not only minimizes inadvertent initiation of quick drop action, as in some of the prior circuits, but also prevents dropping of the load at excessive speeds.
  • the actuation scheme for the bypass valve establishes two conditions which must be satisfied before that valve will open. The first condition is that the directional control valve must be shifted to float position. Since this position usually lies at the opposite side of the power down position from the neutral position, imposition of this condition minimizes the risk of inadvertent initiation ofquick drop action.
  • the second condition precedent to opening of the bypass valve is that the load pressure in the contracting ends of the cylinders must be below a predetermined level indicative of the maximum load which can safely be lowered while quick drop action is in effect. Inclusion of this added condition provides positive insurance against dangerous rates of descent under all conditions of operation.
  • the actuation scheme for the bypass valve preferably is so designed that the pilot pressure signal which shifts the directional control valve to float position develops the motive force which opens the bypass valve.
  • This can be done in several ways.
  • One possibility is to provide the bypass valve with a pressure motor which opens it against a substantially constant bias, and to incorporate a shuttle valve which selectively vents this motor or pressurizes it with fluid drawn from the pilot circuit in accordance with the level of the load pressure in the actuating cylinders.
  • valve-opening motor in continuous communication with the pilot system, and in equipping the bypass valve with an opposed fluid pressure motor which is selectively vented or pressurized by fluid taken from the contracting ends of the cylinders by a load pressure responsive shuttle valve.
  • bypass valve may be controlled by a triggering scheme similar to that shown in Fig. 2 of US. Pat. No. 3,267,961, but including an additional vent valve in series with the vent valve in the directional control valve and which opens and closes the pilot vent path depending upon whether the load pressure in the cylinders is below or above, respectively, the critical level.
  • FIG. 1 is a schematic diagram showing one version of the new circuit incorporating a pilot-operated directional control valve.
  • FIG. 2 is a sectional view of a modified bypass valve which may be used in the Fig. l circuit.
  • the improved circuit is employed to actuate a load 11, which may represent the boom of a front-end loader, and includes a pair of differential area power cylinders 12 and 13, a supply pump 14 and oil reservoir or tank 15, a four-position directional control valve 16, and a regenerative bypass valve 17.
  • the last mentioned valve is located at or near cylinders 12 and 13 and serves to connect them in parallel across the main service lines 18 and 19 leading from directional control valve 16; the head ends and 13a of the cylinders being joined to service line 18 via branch lines 21a and 22a, and the rod ends 12b and 13b being joined to service line 19 via branch lines 21b and 22b.
  • valve 16 includes only the valve unit pertaining to the circuit of the invention.
  • This unit comprises a conventional hollow valve plunger 23 having the following four operative positions: a neutral or hold position N in which it unloads pump 14 to tank 15 through an open center unloading path and precludes flow to and from each of the service lines 18 and 19; a raise position R in which it closes the open center path and connects service lines 18 and 19 with supply line 24 and tank line 25, respectively; a power down position PD in which it closes the open center path and reverses the connectionsbetween the service lines and lines 24 and 25; and a float position F in which it unloads pump 14 and interconnects service lines 18 and 19 through a regeneration path having a restricted bleed connection to tank line 25.
  • Valve plunger 23 is biased to the neutral position by a centering spring 26 and is shifted in opposite directions from this position by a pair of opposed piloted motors 27 and 28, each of which includes one end of the plunger itself.
  • Motors 27 and 28 are operated by pilot pressures supplied to them from a closed center, manually operated, pressuregraduating pilot valve 33.
  • This valve includes an inlet chamber 35 which is connected to receive oil from a small pilot pump 35 at a low pressure (e.g. 200 p.s.i.) determined by relief valve 36, a pair of exhaust chambers 37 and 38 which are connected with tank 15, and a pair of motor ports 39 and 41 which are connected with the motors 27 and 28, respectively, through pilot passages 42 and 43.
  • the pressures at ports 39 and 41 are varied by a sliding valve spool 44 which is provided with a land 45 having a throttling notch 46 or 47 at each end and an axially aligned centrally located, stopped flat 48.
  • the spool is keyed against rotation so that the flat and the notches may register with motor ports 39 and 41, and is provided with through transverse passages 49 which balance the radially directed pressure forces.
  • land 45 isolates inlet chamber 34 from the motor ports and the other chambers, and notches 46 and 47 connect the motor ports with exhaust chambers 37 and 38, respectively. Therefore, under this condition, both of the ports 39 and 41 are vented.
  • port 41 remains vented, but the flow path from port 39 to chamber 37 through notch 46 is gradually restricted, and the peripheral spool edge at the left end of flat 48 gradually opens a flow path from chamber 34 to port 39. Therefore, this movement of spool 44 causes the pressure at port 39 to increase progressively relatively to the pressure at port 41. in a similar manner, rightward movement of the spool effects a progressive increase in the pressure at port 41 relative to the pressure at port 39.
  • Bypass valve 17 comprises a housing formed with three cored chambers 51-53 which are provided with ports through which they are connected with the hydraulic lines 18, 19, 21a, 21b, 22a and 22b in the manner shown in the drawing, and which are spanned by a valve bore 54.
  • This bore contains a reciprocable valve plunger 55 provided with a central land 56 containing a plurality of circumferentially spaced metering slots 57.
  • Valve plunger 55 is biased by compression spring 58 to the illustrated closed position, in which land 56 prevents communication between chambers 52 and 53, and is shifted to the left to open a regeneration path between these chambers by a piston motor 59.
  • This motor is selectively connected with pilot conduit 43 or tank via a shuttle valve 61 which is biased to the illustrated pressurizing position by a spring 62 and is moved to the venting position by an actuating motor 63 which responds to the load pressure in the head ends of cylinders 12 and 13.
  • the size of motor 59 is so correlated with the preload in spring 58 that the motor is able to Shift plunger 55 to open position only when it is pressurized to the level which enables piloted motor 28 to move plunger 23 to float position.
  • Motor 63 and spring 62 are so sized that shuttle valve 61 transmits pilot pressure to motor 59 only as long as the pressure in cylinder ends 120 and 13a is below a predetermined value indicative of the maximum load which can be lowered safely using quick drop action.
  • pilot conduits 42 and 43 will be vented to'tank 15. Therefore, centering spring 26 will hold plunger 23 of directionai control valve 16 in neutral position, and, regardless of the position of shuttle valve 61, spring 58 will keep bypass valve 17 closed.
  • Raising ofload 11 is effected by shifting spool 44 to the left from neutral position to thereby increase the pressure in pilot conduit 42 and cause piloted motor 27 to shift valve plunger 23 to its raise position R.
  • Oil delivered by pump 14 is now supplied to the head ends of cylinders 12 and 13 via lines 24 and 18, chambers 51 and 52 and branch lines 21a and 22a, and the oil displaced from the rod ends 1211 and 13b of the cylinders is returned to tank is via branch tines 21b and 22b, chamber 53, and lines 19 and 25. Since pilot conduit 43 remains vented during the raising operation, bypass valve 17 will stay closed regardless of the position of shuttle valve 61.
  • FIG. 2 EMBODIMENT Figure 2 shows a modified bypass valve 17' incorporating an alternative actuation scheme which accomplishes the same end result as the one employed in Fig. 1, but should be less expensive to manufacture.
  • the motor 59' which shifts bypass plunger 55 in the opening direction, is in continuous communication with pilot conduit 43 and is opposed by a pressure motor 64 as well as by spring 58'.
  • the added motor 64 is selectively pressurized with fluid from chamber 52' or vented to tank by a shuttle valve 6] located within valve plunger 55'.
  • Valve 61 is biased to the illustrated venting position by compression spring 62 and is shifted to the pressurizing position by the fluid in chamber 52 which is applied to its motor surface 63' through a passage 65 formed in plunger 55'. ln the venting position, valve 61 engages its seat 66, to thereby block communication between motor 64 and chamber 52 through passages 67 and 65, and allows the oil in motor 64 to escape substantially freely to tank 15 via an exhaust path ineluding passage 67, an axial passage 68 in valve 61', the slots 69 in the right end of stop sleeve 71, the through passages 72 in spider member 73, and a passage 74 in casing 75.
  • Spring 62 is sized to keep valve 61 in the venting position when the load pressure in chamber 52 is below the critical level indicative of an excessive load; therefore, as in the Fig. 1 embodiment, motor 59 will be able to open bypass valve 17' when the pilot pressure it receives reaches the level which will cause the directional control valve to shift to float position.
  • valve 61' When the load pressure in chamber 52 rises above the setting of valve 61', the valve will shift to the right to the pressurizing position in which it abuts sleeve 71. This action opens communication between chamber 52 and motor 64 and simultaneously causes a pin 76 carried by spider 73 to move into and thus restrict axial passage 68 in the exhaust path leading from motor 64.
  • the restriction to flow through passage 68 is considerably greater than the restriction to flow from chamber 52' to motor 64 through passages 65 and 67; therefore, motor 64 will be subjected to a substantial back pressure proportional to the load pressure in chamber 52.
  • motor 64 will supplement the biasing force exerted by spring 58' and hold valve plunger 55 in its closed position even when motor 59 is subjected to maximum pressure which can be produced by the pilot circuit.
  • quick drop action is precluded when the load is too large for this action to be afforded safely.
  • bypass valve may be actuated by a scheme similar to the one shown in Fig. 2 of US. Pat. No. 3,267,961, but including a load-pressure-responsive vent valve which is in series with the one controlled by the directional control valve and which is opened and closed, respectively, when the load pressure is below and above the critical level.
  • a hydraulic system including a double-acting cylinder (12 or 13) having opposed ends 12a, 12b or 13a, 13b) and arranged to actuate a load (11) which tends to contract the first (12a or 13a) of said ends, directional control valve means 16, 33) for controlling flow to and from said ends and having a float condition in which it establishes a regeneration path between the cylinder ends, and a separate bypass valve (17 or 17') arranged to open and close a second regeneration path between the cylinder ends, the improvement which comprises actuating means (58, 59, 61-63 or 58, 59', 6l63, 64) for opening the bypass valve (17 or 17') only when the pressure in the first cylinder end (120 or 130) is below a predetermined level and the directional control valve means (16, 33) is in float condition.
  • actuating means includes a. means (58) biasing the bypass valve (17) in the closing direction;
  • the directional control valve means includes a directional control valve m (16) having a float position in which it establishes said regeneration path, piloting means (14,
  • the actuating means includes l.
  • a second fluid pressure motor (59) arranged to open the bypass valve (17) against the opposition of a biasing means (58) when subjected to a pressure of said predetermined magnitude, and
  • shuttle valve means responsive to the pressure in the first cylinder end (12a or 13a) for subjecting the second fluid pressure motor to said pilot pressure when the cylinder pressure is below said predetermined level, and, when cylinder pressure is above said level, for venting the second motor.
  • actuating means includes a. a first pressure motor (59) for moving the bypass valve (17) in the opening direction;
  • (1. means, including a valve (61') which responds to the pressure in said first cylinder end (12a or 1311), for subjecting the second motor (64) to a pressure sufficient to enable it to hold the bypass valve closed when the pressure in said cylinder end is above said predetermined level.
  • the directional control valve means includes a directional control valve (16) having a float position in which it establishes said regeneration path, piloting means (14,
  • the actuating means includes 1. a second pressure motor (59) subject continuously to said pilot pressure and sized to open the bypass valve (17') at a pilot pressure of said predetermined magnitude,
  • valve means (6l63) responsive to the pressure in said first cylinder end (12a or 13a) for venting the third fluid pressure motor or pressurizing same to said certain level with fluid from said first cylinder end depending upon whether the pressure in the first cylinder end is below or above, respectively, said predetermined level.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Operation Control Of Excavators (AREA)
US37114A 1970-05-14 1970-05-14 Hydraulic power circuit with rapid lowering provisions Expired - Lifetime US3604313A (en)

Applications Claiming Priority (1)

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US3711470A 1970-05-14 1970-05-14

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US3604313A true US3604313A (en) 1971-09-14

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US (1) US3604313A (enrdf_load_stackoverflow)
JP (1) JPS564761B1 (enrdf_load_stackoverflow)
FR (1) FR2088558B1 (enrdf_load_stackoverflow)
GB (1) GB1297601A (enrdf_load_stackoverflow)
SE (1) SE372316B (enrdf_load_stackoverflow)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3757646A (en) * 1970-05-21 1973-09-11 Sulzer Ag Safety circuit for a working cylinder
US3786827A (en) * 1973-03-16 1974-01-22 Caterpillar Tractor Co Flow control valve
US3965587A (en) * 1974-11-13 1976-06-29 Clark Equipment Company Quick drop control for scrapers
US3987703A (en) * 1974-08-12 1976-10-26 Caterpillar Tractor Co. Combined restrictor and dead engine lowering valve
US4015679A (en) * 1975-05-16 1977-04-05 J. I. Case Company Drive range and lock control system
EP0056770A3 (en) * 1981-01-19 1982-08-18 Bendix Automation Company A regenerative and anti-cavitation hydraulic system for an excavator
US5251705A (en) * 1992-03-19 1993-10-12 Deere & Company Electrical trigger for quick drop valve
US5988028A (en) * 1993-02-02 1999-11-23 Putzmeister Aktiengesellschaft Process for conveying thick matter containing preshredded scrap metal or similar solids
US6699311B2 (en) 2001-12-28 2004-03-02 Caterpillar Inc Hydraulic quick drop circuit
FR2863634A1 (fr) * 2003-12-16 2005-06-17 Volvo Constr Equip Holding Se Engin de travaux publics
WO2008078930A1 (en) 2006-12-22 2008-07-03 Doosan Infracore Co., Ltd. Hydraulic system for improving flatting workability in an excavator
US20080302099A1 (en) * 2006-01-16 2008-12-11 Volvo Construction Equipment Ab Method for Controlling a Hydraulic Cylinder and Control System for a Work Machine
US9340956B2 (en) 2012-10-11 2016-05-17 Cnh Industrial America Llc Boom lock system for work machine
US11053958B2 (en) * 2019-03-19 2021-07-06 Caterpillar Inc. Regeneration valve for a hydraulic circuit

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS602164U (ja) * 1983-06-17 1985-01-09 松下電器産業株式会社 燃焼装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3033168A (en) * 1960-10-31 1962-05-08 New York Air Brake Co Hydraulic mechanism
US3049101A (en) * 1961-04-03 1962-08-14 New York Air Brake Co Hydraulic mechanism
US3267961A (en) * 1964-04-16 1966-08-23 New York Air Brake Co Valve
US3477347A (en) * 1968-05-17 1969-11-11 Gen Signal Corp Hydraulic power circuit affording parallel regeneration paths

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3335739A (en) * 1964-12-03 1967-08-15 New York Air Brake Co Valve

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3033168A (en) * 1960-10-31 1962-05-08 New York Air Brake Co Hydraulic mechanism
US3049101A (en) * 1961-04-03 1962-08-14 New York Air Brake Co Hydraulic mechanism
US3267961A (en) * 1964-04-16 1966-08-23 New York Air Brake Co Valve
US3477347A (en) * 1968-05-17 1969-11-11 Gen Signal Corp Hydraulic power circuit affording parallel regeneration paths

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3757646A (en) * 1970-05-21 1973-09-11 Sulzer Ag Safety circuit for a working cylinder
US3786827A (en) * 1973-03-16 1974-01-22 Caterpillar Tractor Co Flow control valve
US3987703A (en) * 1974-08-12 1976-10-26 Caterpillar Tractor Co. Combined restrictor and dead engine lowering valve
US3965587A (en) * 1974-11-13 1976-06-29 Clark Equipment Company Quick drop control for scrapers
US4015679A (en) * 1975-05-16 1977-04-05 J. I. Case Company Drive range and lock control system
EP0056770A3 (en) * 1981-01-19 1982-08-18 Bendix Automation Company A regenerative and anti-cavitation hydraulic system for an excavator
US5251705A (en) * 1992-03-19 1993-10-12 Deere & Company Electrical trigger for quick drop valve
US6158313A (en) * 1993-02-02 2000-12-12 Putzmeister Aktiengesellschaft Process for conveying thick matter containing preshredded scrap metal or similar solids
US5988028A (en) * 1993-02-02 1999-11-23 Putzmeister Aktiengesellschaft Process for conveying thick matter containing preshredded scrap metal or similar solids
US6699311B2 (en) 2001-12-28 2004-03-02 Caterpillar Inc Hydraulic quick drop circuit
FR2863634A1 (fr) * 2003-12-16 2005-06-17 Volvo Constr Equip Holding Se Engin de travaux publics
WO2005059258A1 (fr) * 2003-12-16 2005-06-30 Volvo Construction Equipment Holding Sweden Ab Engin de travaux publics
US20080302099A1 (en) * 2006-01-16 2008-12-11 Volvo Construction Equipment Ab Method for Controlling a Hydraulic Cylinder and Control System for a Work Machine
US8225706B2 (en) * 2006-01-16 2012-07-24 Volvo Construction Equipment Ab Method for controlling a hydraulic cylinder and control system for a work machine
WO2008078930A1 (en) 2006-12-22 2008-07-03 Doosan Infracore Co., Ltd. Hydraulic system for improving flatting workability in an excavator
EP2094915A4 (en) * 2006-12-22 2014-04-02 Doosan Infracore Co Ltd HYDRAULIC SYSTEM FOR INCREASING THE EFFICIENCY IN A PICKER
US9340956B2 (en) 2012-10-11 2016-05-17 Cnh Industrial America Llc Boom lock system for work machine
US11053958B2 (en) * 2019-03-19 2021-07-06 Caterpillar Inc. Regeneration valve for a hydraulic circuit

Also Published As

Publication number Publication date
SE372316B (enrdf_load_stackoverflow) 1974-12-16
JPS564761B1 (enrdf_load_stackoverflow) 1981-01-31
FR2088558B1 (enrdf_load_stackoverflow) 1975-06-06
DE2122454B2 (de) 1976-11-25
GB1297601A (enrdf_load_stackoverflow) 1972-11-29
DE2122454A1 (de) 1971-11-18
FR2088558A1 (enrdf_load_stackoverflow) 1972-01-07

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