WO1982000861A1 - Systeme de commande de deplacement moteur - Google Patents

Systeme de commande de deplacement moteur Download PDF

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Publication number
WO1982000861A1
WO1982000861A1 PCT/US1979/000067 US7900067W WO8200861A1 WO 1982000861 A1 WO1982000861 A1 WO 1982000861A1 US 7900067 W US7900067 W US 7900067W WO 8200861 A1 WO8200861 A1 WO 8200861A1
Authority
WO
WIPO (PCT)
Prior art keywords
pressure
control system
pressure level
preselected
displacement
Prior art date
Application number
PCT/US1979/000067
Other languages
English (en)
Inventor
J Dezelan
Original Assignee
J Dezelan
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by J Dezelan filed Critical J Dezelan
Priority to PCT/US1979/000067 priority Critical patent/WO1982000861A1/fr
Priority to CA337,559A priority patent/CA1105361A/fr
Publication of WO1982000861A1 publication Critical patent/WO1982000861A1/fr

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Classifications

    • 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
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/38—Control of exclusively fluid gearing
    • F16H61/40—Control of exclusively fluid gearing hydrostatic
    • F16H61/42—Control of exclusively fluid gearing hydrostatic involving adjustment of a pump or motor with adjustable output or capacity
    • F16H61/423—Motor capacity control by fluid pressure control means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/38—Control of exclusively fluid gearing
    • F16H61/40—Control of exclusively fluid gearing hydrostatic
    • F16H61/46—Automatic regulation in accordance with output requirements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/38—Control of exclusively fluid gearing
    • F16H61/40—Control of exclusively fluid gearing hydrostatic
    • F16H61/46—Automatic regulation in accordance with output requirements
    • F16H61/472—Automatic regulation in accordance with output requirements for achieving a target output torque
    • 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
    • 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
    • F15B2211/30—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
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/327—Directional control characterised by the type of actuation electrically or electronically
    • 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
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief 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
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5151—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a 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
    • F15B2211/50—Pressure control
    • F15B2211/55—Pressure control for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief 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
    • F15B2211/60—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
    • F15B2211/705—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
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7058—Rotary 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
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • 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
    • F15B2211/7114—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators
    • F15B2211/7128—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators the chambers being connected in parallel
    • 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
    • F15B2211/755—Control of acceleration or deceleration 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
    • F15B2211/77—Control of direction of movement of the output member

Definitions

  • This invention relates to a control system for a variable displacement drive motor, and more particularly to a system for reducing the displacement of the drive motor in response to the loading demand requirements of an auxiliary motor.
  • the drive motors are operated substantially continually when front wheel drive power is required.
  • the auxiliary equipment is operated only intermittently.
  • the capacity of the pump is generally dictated for economic reasons on the requirements of the continually operated wheel drive motors.
  • the auxiliary equipment is operated at a time when the variable displacement drive motors are demanding substantially all the available capacity of the pump, there is often insufficient fluid under the pressure required to operate the auxiliary equipment motor.
  • a pressure compensating spool is incorporated to establish a minimum pressure level for operation of the pair of front wheel drive motors. If the speed of the vehicle is so high as to demand more flow capacity from the pump than is available, than such pressure compensating spool automatically acts through this sytem to destroke the motors and maintain at least that pressure level. Unfortunately, simultaneous operation of an auxiliary motor would be limited to that same preestablished minimum pressure level, even though a higher pressure is required for satisfactory performance of the loaded auxiliary motor.
  • the present invention is directed to overcoming one or more of the problems as set forth above.
  • a motor displacement control system includes a variable displacement drive motor, an auxiliary motor, a source of pressure fluid for operating the motors, first means for controlling the displacement of the drive motor and maintaining at least a first pressure level, and second means for controlling the displacement of the drive motor in response to operation of the auxiliary motor at a second pressure level and overriding the first means .
  • control system of the present invention finds particular utility in a motor grader equipped with a pair of variable displacement front wheel drive motors, and wherein operation of an auxiliary motor at a high pressure is simultaneously possible by valve means which overrides operation of a drive motor minimum pressure level establishing valve, such valve means generally establishing pressure signals for destroking the wheel drive motors.
  • the motor displacement control system 10 of the present invention includes a pressure compensated, variable displacement pump 12 connected to a fluid reservoir 14 by an intake conduit 16.
  • the pump can have a present compensation of 24,130 kPa (3500 psi) , for example.
  • this engine driven pump supplies hydraulic fluid under pressure to a main flow control valve 18 and to a plurality of implement or auxiliary circuits 20, 22 and 24 via conduits 26 and 28 respectively.
  • each of the circuits has an implement or auxiliary motor 30 and is connected to a load signal output line 32 via a check valve 34.
  • the implement motor for the third auxiliary circuit can be for lowering and raising an earthmoving implement, for example..
  • the flow control valve 18 is a conventional solenoid operated on-off valve, and when in the open position shown conveys fluid from the pump 12 and conduit 26 to a pair of conduits 36 connected to each of two variable displacement, rotary output, hydraulic drive motors 38.
  • these motors are of the axial piston, swashplate-operated type.
  • One of the drive motors 38 is adapted to drive a left front wheel 40, while the other is adapted to drive a right front wheel 42, each through an associated output clutch 44 as is diagrammatically illustrated.
  • a pilot line 46 and associated branch lines 47 and 48 are connected to the conduits 36 leading to the wheel drive motors 38 and to pressure compensating valve means (5) .
  • Such valve means controls the displacement of the wheel drive motors and maintains at least a first pressure level threat, for example a minimum pressure of about 12,400 kPa (1800 psi) .
  • the pressure compensating valve means includes a housing 52 having a bore 54, an inlet port 56, a control, port 58, an outlet port 60, and a drain port 62.
  • a pressure compensating valve spool 66 having lands 68, 70, and 72 is reciprocally mounted in the bore such that a spring chamber 74 is formed at the left end when viewing the drawing and a pressure or reaction chamber 76 is formed at the right end.
  • a compression spring 78 serves to bias the spool to the right when viewing the drawing against the pressure in the chamber 76.
  • the control port 58 of the pressure compensating valve means 50 is in fluid communication with a conventional, solenoid-actuated, directional control valve 80 via a line 82.
  • the directional control valve is utilized to control the direction, of rotation of the output of the wheel drive motors 38 via first and second control lines 84, 86 which extend to the swashplate controls 88 of the separate motors.
  • first and second control lines 84, 86 which extend to the swashplate controls 88 of the separate motors.
  • the greater the pressure differential between the cpntr.ol lines 84 and 86 the greater the displacement of the wheel drive motors.
  • the directional control valve 80 has a solenoid 90 at its left end when viewing the drawing which, when actuated, will move a spool 92 to the right against the bias of a spring 94 to a reverse mode of operation. When not actuated, the spool will take a leftward or a forward mode of operation as illustrated. In forward, as shown, the lines 82, 84 are connected and the line 86 is in fluid communication with a line 96 across the valve spool. On the other hand, in reverse, the lines 84 and 96 are connected and the lines 82 and 86 are connected.
  • control system 10 includes priority valve means 98 for overriding the pressure compensating valve means 50 and controlling the displacement of the wheel drive motors 38 in response to operation of one or more of the auxiliary circuits 20, 22, 24 and associated motors 30 at least at a second pressure level below the minimum first pressure level setting of the pressure compensating valve means, and for establishing at least a relatively higher third or load pressure level above the first pressure level setting at the auxiliary motor.
  • the second pressure level setting of the priority valve means 98 can be 11 , 000 kPa ( 1600 psi)
  • the first pressure level setting can be 12,400 kPa (1800 psi) as mentioned previously
  • the third or load pressure level can be 17,200 kPa (2500 psi) .
  • the priority valve means 98 includes a housing 100. having a bore 102, a pair of drain ports 104, 106 opening on the bore, and three control ports 108, 110, 112 also opening on the bore.
  • a priority valve spool 114 having axially spaced lands 116, 118 and 120 is reciprocally disposed in the bore and defines with the housing a spring chamber 122 at the left end when viewing the drawing, and a pressure or reaction chamber 124 at the right end.
  • a compressing spring 126 biases the priority spool to the right against pressure in the reaction chamber, and it is to be noted that the reaction chamber is connected to the load signal output line 32 of the auxiliary circuits 20, 22, 24.
  • a branch line 128 having a flow restricting orifice 130 therein is connected to the line 32 and the reservoir 14 for the purpose of draining the reaction chamber 124 so that the priority valve can return to the right to its inactive poisition, as illustrated, without a fluid trap.
  • ports 108 and 110 are connected to the lines 82 and 96 respectively, and port 112 is connected directly to outlet port 60 of pressure compensating valve means 50.
  • Fluid directed to the wheel drive motors 38 for operation thereof via the pair of inlet conduits 36 is returned to a drain annulus 132 of the main flow control valve 18 via a pair of outlet conduits 134, and from there back to the reservoir 14 by way of a conduit 136 and a low pressure setting check valve 138.
  • the main spool 140 In the wheel drive motor operating position, the main spool 140 is biased to the left as shown by the communication of line pressure in conduit 26 to a reaction chamber 142 via an open solenoid operated shut-off valve 144.
  • the valve 144 can be remotely closed to block flow of pressure fluid to the reaction chamber 142 and to allow the pressure to bleed down therefrom through a flow restrictin orifice 146, leading to the outlet conduit 134 thereupon permitting a compressing spring 147 to bias spool 140 to the right blocking communication of pressure fluid in line 26 from the inlet conduits 36. Excessive pressure in the inlet conduits 36 is relieved back to the reservoir via the line 136 and a pressure relief valve 148 having a relativel high setting for example about 30,300 kPa (4400 psi).
  • Another pair of drain lines 150 communicate excess fluid in the case of the wheel drive motors back to the reservoir via another low pressure setting check valve 152 in the usual manner.
  • the pressure compensating valve means 50 operates to alter the displacement of the wheel drive motors 38 to maintain the previously noted minimum pressure level of 12,400 kPa (1800 psi).
  • the spool 66 maintains a position substantially, as shown.
  • the pressure level drops in the conduits 36.
  • the line 82 is no longer in open communication with the reservoir, but rather is meteringly supplied with pressure fluid from the pilot line 46.
  • the valve spool 66 desirably hovers with land 70 radially aligned with port 58 to supply a controlled balancing pressure to line 82 and the first control line 84.
  • the second control line 86 to the wheel drive motors 38 is maintained at the pressure in the main supply conduit 26 via lines 46 and 47 and the directional control valve 80.
  • the pressure in the control line 84 increases relative to the pressurein the control lihe 86 to destroke the wheel drive motors, that is to reduce their displacement, thereby maintaining at least the above noted minimum pressure level.
  • the pressure level setting of the pressure compensating valve means 50 is determined by the spring constant of the spring 78 and the distance the central land 70 must travel from the fully right position of the spool 66 to the metering position.
  • one of the hydraulic motors 30 associated with a circuit 20, 22, or 24 can require fluid at a higher pressure than the preselected pressure level setting of the pressure compensating valve means 50 to perform its function satisfactorily.
  • the priority valve means 98 allows this need to be met by, in affect, overriding the compensating valve means 50.
  • the highest pressure in the load signal output line 32 from one of the motors 30 is communicated to the reaction chamber 124 of the priority valve means.
  • the priority valve spool 114 shifts to the left when viewing the drawing from the position illustrated against the load of the spring 126.
  • the wheel drive motors are free to rotate with the wheels 40, 42 since the clutches 44 remain engaged, but with no torque being transmitted to the wheels, so that the pressure in the main conduits 26, 36 can increase to the point necessary to effectively operate the auxiliary motor 30 at the desired capacity.
  • the check valves 34 serve to isolate the circuits 20, 22, and 24 from one another, while allowing the highest pressure load signal in any one to be directed to the reaction chamber 124 via signal line 32.
  • the pressure compensated, variable displacement pump 12 has a capacity about equal to the demand capacity of the wheel drive motors 38 at a given wheel speed, for example corresponding to a vehicle velocity of 6.4 km/h (4 mph) .
  • These front wheel drive motors provide auxiliary pwoer, to supplement the drive torque of the conventionally driven rear wheels, particularly at the low speed end of the vehicles normal operating range, and at progressively higher speeds the swashplate controls 88 distroke the drive motors toward minimum displacement.
  • the pressure compensating valve means 50 reduces the displacement of the drive motors to enable priority flow delivery to the auxiliary circuits .
  • the pressure compensating valve spool 66 shifts to the right from the position illustrated, aligns the central land 70 with the port 58, meters pressur fluid to the line 82, and decreases the pressure differential between the first and second control lines 84,86.
  • the priority valve means 98 is ineffective, such as by remaining in the position shown.
  • auxiliary motors 30 require more pressure corresponding to a load signal pressure above about 11,000 kPa (1600 psi) in the line 32
  • priority valve means 98 functions to provide flow priority to the auxiliary motor.
  • priority valve spool 114 moves to the left from the position shown to reduce the pressure differential between control lines 84 and 86, and to cause the swashplates of the wheel drive motors 38 to move toward minimum displacement.
  • the auxiliary motor can be operated at 20,700 kPa (3000 psi) for example.
  • the motor displacement control system 10 of the present invention allows close matching of the capacity of the pump 12 and the motors 30,38 to provide for economical construction, effective priority operation for one of the auxiliary motors 30 at the desired pressure, and yet establishes a minimum effective operating pressure of the wheel drive motors 38 by controllably altering the displacement of the wheel drive motors.
  • valve 98 is preferably established at about 1380 kPa (200 psi) below that of valve 50 because of the possibility of tolerance variations in the components of these two valves upon their initial pressure level setting, and further because of the possibility of pressure losses in the associated lines and conduits due to high flow rates, it is contemplated that the initial setting of priority valve means 98 can be substantially the same as that of the pressurecompensating valve means 50 without departing from the spirit of the present invention.
  • Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure and the appended claims.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Operation Control Of Excavators (AREA)

Abstract

Un systeme de commande de deplacement moteur (10) possede un moteur d'entrainement a deplacement variable (38), un moteur auxiliaire (30), une source de fluide sous pression (12) pour faire fonctionner les moteurs (30, 38), une premiere soupape (50) pour commander le deplacement du moteur d'entrainement (38) et maintenir au moins un premier niveau de pression pour ce dernier, et une seconde soupape (98) pour commander le deplacement du moteur d'entrainement (38) en reponse au fonctionnement du moteur auxiliaire (30) a un second niveau de pression et annuler l'effet de la premiere soupape (50). Le systeme est particulierement utile sur une niveleuse a moteur.
PCT/US1979/000067 1979-02-08 1979-02-08 Systeme de commande de deplacement moteur WO1982000861A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/US1979/000067 WO1982000861A1 (fr) 1979-02-08 1979-02-08 Systeme de commande de deplacement moteur
CA337,559A CA1105361A (fr) 1979-02-08 1979-10-15 Regulateur pour moteur a cylindree variable

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US18953790208 1979-02-08
PCT/US1979/000067 WO1982000861A1 (fr) 1979-02-08 1979-02-08 Systeme de commande de deplacement moteur
WOUS79/00067 1979-02-08

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WO1982000861A1 true WO1982000861A1 (fr) 1982-03-18

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Application Number Title Priority Date Filing Date
PCT/US1979/000067 WO1982000861A1 (fr) 1979-02-08 1979-02-08 Systeme de commande de deplacement moteur

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WO (1) WO1982000861A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2550841A1 (fr) * 1983-07-26 1985-02-22 Linde Ag Dispositif de commande pour un entrainement comportant un tiroir rotatif a deux points d'etranglement pour le reglage de la pression de commande

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3984978A (en) * 1974-11-22 1976-10-12 The Cessna Aircraft Company Auxiliary front wheel drive

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3984978A (en) * 1974-11-22 1976-10-12 The Cessna Aircraft Company Auxiliary front wheel drive

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2550841A1 (fr) * 1983-07-26 1985-02-22 Linde Ag Dispositif de commande pour un entrainement comportant un tiroir rotatif a deux points d'etranglement pour le reglage de la pression de commande
GB2144242A (en) * 1983-07-26 1985-02-27 Linde Ag A machine control arrangement

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