WO2011140184A2 - Pump power control method for preventing stall - Google Patents

Pump power control method for preventing stall Download PDF

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Publication number
WO2011140184A2
WO2011140184A2 PCT/US2011/035127 US2011035127W WO2011140184A2 WO 2011140184 A2 WO2011140184 A2 WO 2011140184A2 US 2011035127 W US2011035127 W US 2011035127W WO 2011140184 A2 WO2011140184 A2 WO 2011140184A2
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WO
WIPO (PCT)
Prior art keywords
pump
pressure
commanded
demanded
determining
Prior art date
Application number
PCT/US2011/035127
Other languages
French (fr)
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WO2011140184A3 (en
Inventor
Amir Shenouda
Original Assignee
Parker Hannifin Corporation
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Filing date
Publication date
Application filed by Parker Hannifin Corporation filed Critical Parker Hannifin Corporation
Publication of WO2011140184A2 publication Critical patent/WO2011140184A2/en
Publication of WO2011140184A3 publication Critical patent/WO2011140184A3/en

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Classifications

    • 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
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • E02F9/2232—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps
    • E02F9/2235—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps including an electronic controller
    • 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
    • E02F9/2278—Hydraulic circuits
    • E02F9/2292—Systems with two or more pumps
    • 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
    • E02F9/2278—Hydraulic circuits
    • E02F9/2296—Systems with a variable displacement pump
    • 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
    • F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
    • F15B11/163—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for sharing the pump output equally amongst users or groups of users, e.g. using anti-saturation, pressure compensation
    • 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
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/25—Pressure control functions
    • 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
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6306—Electronic controllers using input signals representing a pressure
    • F15B2211/6313—Electronic controllers using input signals representing a pressure the pressure being a load 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
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/633—Electronic controllers using input signals representing a state of the prime mover, e.g. 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
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6346—Electronic controllers using input signals representing a state of input means, e.g. joystick position
    • 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
    • F15B2211/6652—Control of the pressure source, e.g. control of the swash plate angle
    • 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
    • F15B2211/6654—Flow rate control
    • 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
    • F15B2211/78—Control of multiple output members

Definitions

  • the present invention relations to a pump power control method for preventing stall and, more particularly, to a pump power control method for use in a multi-function system, such as an excavator.
  • Excavators have five main functions; boom, arm, bucket, swing, and tracks. Hydraulic systems for excavators usually have two pumps to control these functions. Pump control in such hydraulic systems can be complicated because of the different scenarios in operation of an excavator. The three main scenarios are: (i) only implements are used (boom, arm, bucket, and/or swing); (ii) only tracks are used; and (iii) both the tracks and one or more implements are used at the same time. [0004] In a typical hydraulic system, one pump is associated with controlling the boom and arm functions and one of the two tracks. The other pump is associated with controlling bucket and swing functions and the other of the two tracks.
  • the system logic allows the two pumps to be combined. If only the tracks are used, one pump controls the left track and the other pump controls the right track. If both the tracks and one or more of the implement functions are used at the same time, one pump controls both tracks and the other pump controls the implement(s).
  • the pumps supply the flow and pressure to achieve the speed commanded by a system operator for moving the tracks or implements.
  • the pumps usually cannot supply maximum flow at the maximum pressure due to the horsepower limitations of the driving engine or motor.
  • Each pump has a given power curve that traces how much flow is available at a given pressure given a specific power input to the pumps.
  • Fig. 2 illustrates an example of such a curve.
  • At least one embodiment of the invention provides a method of controlling one or more pumps in a hydraulic system associated with multiple functions in response to operator commands indicative of commanded speed and direction of each actuated function, the method comprising the steps of: determining commanded flow in response to commanded speed; determining pressure demanded by each actuated function; determine maximum available flow given the determined demanded pressure; divide the determined maximum available flow by the determined commanded flow; and multiply commanded speeds by the ratio.
  • At least one embodiment of the invention provides a method of controlling the pressure output of one or more pumps in a hydraulic system associated with multiple functions in response to operator commands indicative of a commanded speed and direction of each actuated function, the method comprising the steps of: determining a commanded hydraulic fluid flow in response to a commanded speed of each actuated function; determining a pressure demanded by each actuated function; determining a maximum available hydraulic fluid flow given the determined pressure demanded by the actuated functions; dividing the determined maximum available hydraulic fluid flow by the determined commanded flow to obtain a ratio; and multiplying commanded speeds by the ratio to obtain the operational hydraulic fluid flow so that the hydraulic fluid flow demand is never greater than the maximum available hydraulic fluid flow.
  • At least one embodiment of the invention provides a pump power control method for a hydraulic system adapted to actuate multiple functions in response to operator commands in a manner preventing the stall of an engine driving a pump of the hydraulic system, the method comprising the steps of: determining a commanded speed and direction of each actuated function based on an operator input, determining a commanded hydraulic fluid flow in response to the determined commanded speed of each actuated function; determining a pressure demanded by each actuated function; signaling a pump to achieve the pressure demanded; determining a maximum available hydraulic fluid flow given the determined pressure demanded by the actuated functions; dividing the determined maximum available hydraulic fluid flow by the determined commanded hydraulic fluid flow to obtain a ratio; and multiplying the commanded speeds by the ratio to obtain the operational hydraulic fluid flow so that the operational hydraulic fluid flow is never greater that the maximum available hydraulic fluid flow.
  • At least one embodiment of the invention provides a pump power control method for a hydraulic system adapted to actuate multiple functions in response to operator commands in a manner preventing the stall of an engine of the hydraulic system, the method comprising the steps of: determining a commanded speed and direction of each actuated function based on an operator input, determining the power required by the pump to achieve the commanded S speed of each actuated function; reducing the commanded speed of each actuated function by a ratio equivalent to a maximum available pump flow divided by a pump flow demanded by the commanded speed.
  • FIG. 1 illustrates a hydraulic circuit for an excavator according to an exemplary embodiment of the present invention
  • FIG. 2 illustrates typical power curves for a pump with pressure (current) on X-Axis and flow on Y axis and the different engine speeds;
  • FIG. 3 illustrates a typical pump curve showing pressure vs. current
  • FIG. 4 is a schematic illustration of a portion of the system for performing the method of the present invention.
  • This invention provides a method of controlling or manipulating the commanded flow (i.e., commanded speeds) so that the pump power demand does not over demand the associated engine or motor. Over demanding the a associated engine or motor may cause it to stall.
  • the present invention provides this method without the need for elaborate or complex hardware systems.
  • Fig. 1 illustrates a hydraulic circuit for an excavator according to an exemplary embodiment of the present invention.
  • the pumps 10 and 12 have electronic means 16 and 18 controlling the pressure output to match the pressure required to move the function or implement being actuated. So, for example, a certain current command corresponds to a certain pressure output from the pump, as is illustrated in the graph of Fig. 3. Power curves for the pumps are generated to trace how much flow is available at a given pressure (current) given a certain engine (or motor) speed and power, similar to the graphs of Fig. 2.
  • a controller 20 of the system calculates how much flow is being demanded by the machine operator in response to signals received from the operator input device 22, such as the joystick. At the same, time the controller 20 determines how much pressure is demanded by the functions (implements) being actuated, such as in response to load sensors 32, and sends a current to the associated pump control means 16 and 18 to achieve that pressure.
  • the controller 20 then accesses a look-up table associated with the curve that is, for example, stored in memory 36 to determine the maximum flow available from the pump given the demanded pressure so that the engine (or motor) 38 does not stall. That maximum available flow is compared to the commanded flow by the controller 20 and, the controller determines a ratio by dividing the maximum available flow by the commanded flow. The controller 20 then multiplies the commanded speeds by the determined ratio so that the overall or operational flow demand is reduced to no more than the maximum flow available. The speeds of the actuated functions thus are reduced proportionally to operational speeds and the engine (or motor) 38 does not stall because the power demand is equal to the engine output or pump input power.
  • the controller 20 is capable of making these calculations for one of the pumps 10 or 12 or both pumps 10 and 12 depending on which functions are being actuated.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • Operation Control Of Excavators (AREA)

Abstract

A method of controlling or manipulating the commanded flow (i.e., commanded speeds) of a hydraulically actuated system (such as an excavator) is provided so that the pump power demand does not over demand the associated engine or motor which may cause it to stall. A controller (20) calculates how much flow is demanded by means of a joystick (22) signal, and how much pressure is required by means of load sensors (32). When the maximum available pump flow is lower that the total demanded flow for the functions of the hydraulic system operated simultaneously, the flow for each function is reduced according to the ratio between the available flow and the total demanded flow.

Description

PUMP POWER CONTROL METHOD FOR PREVENTING STALL
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of the filing date of U.S. Provisional Patent Application No. 61/330,926, filed May 4, 2010, the disclosure of which is incorporated herein by reference in its entirety.
FIELD OF INVENTION
[0002] The present invention relations to a pump power control method for preventing stall and, more particularly, to a pump power control method for use in a multi-function system, such as an excavator.
BACKGROUND OF THE INVENTION
[0003] Excavators have five main functions; boom, arm, bucket, swing, and tracks. Hydraulic systems for excavators usually have two pumps to control these functions. Pump control in such hydraulic systems can be complicated because of the different scenarios in operation of an excavator. The three main scenarios are: (i) only implements are used (boom, arm, bucket, and/or swing); (ii) only tracks are used; and (iii) both the tracks and one or more implements are used at the same time. [0004] In a typical hydraulic system, one pump is associated with controlling the boom and arm functions and one of the two tracks. The other pump is associated with controlling bucket and swing functions and the other of the two tracks. However, if a function requires a significant fluid flow, the system logic allows the two pumps to be combined. If only the tracks are used, one pump controls the left track and the other pump controls the right track. If both the tracks and one or more of the implement functions are used at the same time, one pump controls both tracks and the other pump controls the implement(s).
[0005] The above description is for a typical system, but machines may have variations of this scheme or different schemes altogether. In different prior art systems, the pumps supply the flow and pressure to achieve the speed commanded by a system operator for moving the tracks or implements. The pumps usually cannot supply maximum flow at the maximum pressure due to the horsepower limitations of the driving engine or motor. Each pump has a given power curve that traces how much flow is available at a given pressure given a specific power input to the pumps. Fig. 2 illustrates an example of such a curve.
SUMMARY OF THE INVENTION
[0006] At least one embodiment of the invention provides a method of controlling one or more pumps in a hydraulic system associated with multiple functions in response to operator commands indicative of commanded speed and direction of each actuated function, the method comprising the steps of: determining commanded flow in response to commanded speed; determining pressure demanded by each actuated function; determine maximum available flow given the determined demanded pressure; divide the determined maximum available flow by the determined commanded flow; and multiply commanded speeds by the ratio.
[0007] At least one embodiment of the invention provides a method of controlling the pressure output of one or more pumps in a hydraulic system associated with multiple functions in response to operator commands indicative of a commanded speed and direction of each actuated function, the method comprising the steps of: determining a commanded hydraulic fluid flow in response to a commanded speed of each actuated function; determining a pressure demanded by each actuated function; determining a maximum available hydraulic fluid flow given the determined pressure demanded by the actuated functions; dividing the determined maximum available hydraulic fluid flow by the determined commanded flow to obtain a ratio; and multiplying commanded speeds by the ratio to obtain the operational hydraulic fluid flow so that the hydraulic fluid flow demand is never greater than the maximum available hydraulic fluid flow. [0008] At least one embodiment of the invention provides a pump power control method for a hydraulic system adapted to actuate multiple functions in response to operator commands in a manner preventing the stall of an engine driving a pump of the hydraulic system, the method comprising the steps of: determining a commanded speed and direction of each actuated function based on an operator input, determining a commanded hydraulic fluid flow in response to the determined commanded speed of each actuated function; determining a pressure demanded by each actuated function; signaling a pump to achieve the pressure demanded; determining a maximum available hydraulic fluid flow given the determined pressure demanded by the actuated functions; dividing the determined maximum available hydraulic fluid flow by the determined commanded hydraulic fluid flow to obtain a ratio; and multiplying the commanded speeds by the ratio to obtain the operational hydraulic fluid flow so that the operational hydraulic fluid flow is never greater that the maximum available hydraulic fluid flow.
[0009] At least one embodiment of the invention provides a pump power control method for a hydraulic system adapted to actuate multiple functions in response to operator commands in a manner preventing the stall of an engine of the hydraulic system, the method comprising the steps of: determining a commanded speed and direction of each actuated function based on an operator input, determining the power required by the pump to achieve the commanded S speed of each actuated function; reducing the commanded speed of each actuated function by a ratio equivalent to a maximum available pump flow divided by a pump flow demanded by the commanded speed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Fig. 1 illustrates a hydraulic circuit for an excavator according to an exemplary embodiment of the present invention;
[0011] Fig. 2 illustrates typical power curves for a pump with pressure (current) on X-Axis and flow on Y axis and the different engine speeds;
[0012] Fig. 3 illustrates a typical pump curve showing pressure vs. current; and
[0013] Fig. 4 is a schematic illustration of a portion of the system for performing the method of the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
[0014] This invention provides a method of controlling or manipulating the commanded flow (i.e., commanded speeds) so that the pump power demand does not over demand the associated engine or motor. Over demanding the a associated engine or motor may cause it to stall. The present invention provides this method without the need for elaborate or complex hardware systems.
[0015] Fig. 1 illustrates a hydraulic circuit for an excavator according to an exemplary embodiment of the present invention. The pumps 10 and 12 have electronic means 16 and 18 controlling the pressure output to match the pressure required to move the function or implement being actuated. So, for example, a certain current command corresponds to a certain pressure output from the pump, as is illustrated in the graph of Fig. 3. Power curves for the pumps are generated to trace how much flow is available at a given pressure (current) given a certain engine (or motor) speed and power, similar to the graphs of Fig. 2.
[0016] A controller 20 of the system calculates how much flow is being demanded by the machine operator in response to signals received from the operator input device 22, such as the joystick. At the same, time the controller 20 determines how much pressure is demanded by the functions (implements) being actuated, such as in response to load sensors 32, and sends a current to the associated pump control means 16 and 18 to achieve that pressure.
[0017] The controller 20 then accesses a look-up table associated with the curve that is, for example, stored in memory 36 to determine the maximum flow available from the pump given the demanded pressure so that the engine (or motor) 38 does not stall. That maximum available flow is compared to the commanded flow by the controller 20 and, the controller determines a ratio by dividing the maximum available flow by the commanded flow. The controller 20 then multiplies the commanded speeds by the determined ratio so that the overall or operational flow demand is reduced to no more than the maximum flow available. The speeds of the actuated functions thus are reduced proportionally to operational speeds and the engine (or motor) 38 does not stall because the power demand is equal to the engine output or pump input power.
[0018] Depending on the scenario, the controller 20 is capable of making these calculations for one of the pumps 10 or 12 or both pumps 10 and 12 depending on which functions are being actuated.
[0019] Although the principles, embodiments and operation of the present invention have been described in detail herein, this is not to be construed as being limited to the particular illustrative forms disclosed. They will thus become apparent to those skilled in the art that various modifications of the embodiments herein can be made without departing from the spirit or scope of the invention.

Claims

a CLAIMS What is claimed is:
1. A method of controlling one or more pumps in a hydraulic system associated with multiple functions in response to operator commands indicative of commanded speed and direction of each actuated function, the method comprising the steps of:
determining commanded flow in response to commanded speed;
determining pressure demanded by each actuated function;
determine maximum available flow given the determined demanded pressure;
dividing the determined maximum available flow by the determined commanded flow to obtain a ratio; and
multiplying commanded speeds by the ratio to obtain operational speeds.
2. The method of claim 1 further comprising the step of controlling the pump to provide the demanded pressure.
3. The method of any of the previous claims wherein the step of determining the maximum available flow given the determined demanded pressure is accomplished using predetermined performance data for a pump flow at a particular pressure at a specific engine speed.
4. The method of any of the previous claims wherein the commanded speed is provided by operator movement of a joystick.
5. The method of claim 2 wherein the step of controlling the pump to provide the demanded pressure utilizes electronic means of controlling the pressure output of the pump.
6. A method of controlling the pressure output of one or more pumps in a hydraulic system associated with multiple functions in response to operator commands indicative of a commanded speed and direction of each actuated function, the method comprising the steps of:
determining a commanded hydraulic fluid flow in response to a
commanded speed of each actuated function;
determining a pressure demanded by each actuated function;
determining a maximum available hydraulic fluid flow given the determined pressure demanded by the actuated functions ;
dividing the determined maximum available hydraulic fluid flow by the determined commanded flow to obtain a ratio; and
multiplying commanded speeds by the ratio to obtain the operational hydraulic fluid flow so that the hydraulic fluid flow demand is never greater than the maximum available hydraulic fluid flow.
7. The method of claim 6 further comprising the step of signaling the pump to provide the demanded pressure.
8. The method of any of claims 6 or 7, wherein the step of determining the maximum available flow given the determined demanded pressure is
accomplished using predetermined performance data for a pump flow at a particular pressure at a specific engine speed.
9. The method of any of claims 6-8, wherein the commanded speed is provided by operator movement of a joystick.
10. The method of claim 7 wherein the step of signaling the pump to provide the demanded pressure utilizes electronic means of controlling the pressure output of the pump.
11. A pump power control method for a hydraulic system adapted to actuate multiple functions in response to operator commands in a manner preventing the stall of an engine driving a pump of the hydraulic system, the method comprising the steps of:
determining a commanded speed and direction of each actuated function based on an operator input,
determining a commanded hydraulic fluid flow in response to the determined commanded speed of each actuated function;
determining a pressure demanded by each actuated function;
signaling a pump to achieve the pressure demanded;
determining a maximum available hydraulic fluid flow given the determined pressure demanded by the actuated functions;
dividing the determined maximum available hydraulic fluid flow by the determined commanded hydraulic fluid flow to obtain a ratio; and
multiplying the commanded speeds by the ratio to obtain the operational hydraulic fluid flow so that the operational hydraulic fluid flow is never greater that the maximum available hydraulic fluid flow.
12. The method of claim 11 wherein the step of determining the maximum available flow given the determined demanded pressure is accomplished using predetermined performance data for a pump flow at a particular pressure at a specific engine speed.
13. The method of any of claims 11 or 12 wherein the commanded speed is provided by operator movement of a joystick.
14. The method of claim 11 wherein the step of signaling the pump to provide the demanded pressure utilizes electronic means of controlling the pressure output of the pump.
15. A pump power control method for a hydraulic system adapted to actuate multiple functions in response to operator commands in a manner preventing the stall of an engine of the hydraulic system, the method comprising the steps of: determining a commanded speed and direction of each actuated function based on an operator input,
determining the power required by the pump to achieve the commanded speed of each actuated function;
reducing the commanded speed of each actuated function by a ratio equivalent to a maximum available pump flow divided by a pump flow demanded by the commanded speed.
16. The method of claim 15 wherein the step of determining the power required by the pump to achieve the commanded speed of each actuated function includes the step of determining a commanded hydraulic fluid flow in response to the determined commanded speed of each actuated function.
17. The method of any of claims 15 or 16 wherein the step of determining the power required by the pump to achieve the commanded speed of each actuated function includes the step of determining a pressure demanded by each actuated function.
18. The method of claim 17 further including the step of controlling the pump to achieve the pressure demanded.
19. The method of claim 15 wherein the step of reducing the commanded speed of each actuated function includes the step of determining the maximum available hydraulic fluid flow given the determined pressure demanded by the actuated functions.
20. The method of claim 19 wherein the step of determining the maximum available hydraulic fluid flow given the determined pressure demanded by the actuated functions is accomplished using predetermined performance data for a pump flow at a particular pressure at a specific engine speed.
PCT/US2011/035127 2010-05-04 2011-05-04 Pump power control method for preventing stall WO2011140184A2 (en)

Applications Claiming Priority (2)

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US33092610P 2010-05-04 2010-05-04
US61/330,926 2010-05-04

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WO2011140184A3 WO2011140184A3 (en) 2012-03-15

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