COMMAND BASED METHOD FOR ALLOCATING FLUID FLOW FROM A PLURALITY OF PUMPS TO MULTIPLE HYDRAULIC FUNCTIONS

• US 20110308242A1
• Filed: 06/13/2011
• Published: 12/22/2011
• Est. Priority Date: 06/21/2010
• Status: Active Grant

• Current Assignee: Husco International Incorporated
• Original Assignee: Husco International Incorporated
• Inventors: Pfaff, Joseph L., Hamkins, Eric P., Quinnell, Corey K.
• Granted Patent: US 9,032,724 B2
• Time in Patent Office: Days
• US Class Current: 60/327
• CPC Class Codes: E02F 9/2242 including an electronic controller
• CPC Class Codes: E02F 9/2292 Systems with two or more pumps
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump
• CPC Class Codes: F15B 11/17 using two or more pumps
• CPC Class Codes: F15B 2211/20523 Internal combustion engine
• CPC Class Codes: F15B 2211/20546 variable capacity
• CPC Class Codes: F15B 2211/20576 with multiple pumps
• CPC Class Codes: F15B 2211/265 Control of multiple pressure sources
• CPC Class Codes: F15B 2211/30575 in a Wheatstone Bridge arrangement (also half bridges)
• CPC Class Codes: F15B 2211/6306 representing a pressure
• CPC Class Codes: F15B 2211/6309 the pressure being a pressure source supply pressure
• CPC Class Codes: F15B 2211/6313 the pressure being a load pressure
• CPC Class Codes: F15B 2211/6346 representing a state of input means, e.g. joystick position

Abstract

Fluid from two pumps is allocated to a plurality of hydraulic actuators based on a plurality of flow commands, each specifying a desired amount of flow to be applied to a different hydraulic actuator. For a given hydraulic actuator, the allocation involves (1) determining an apportionment of the desired amount of flow, if no other hydraulic actuator is active, and (2) altering the apportionment in response to all the plurality of flow commands, and (3) using the altered apportionment to determine a first amount of the flow for one pump to provide and a second amount of the flow for the other pump to provide. The process is repeated for all the hydraulic actuators. Supply valves for each hydraulic actuator are controlled by the associated first and second amounts and each pump is controlled in response to either the first or second amounts for all the hydraulic actuators.

Claims

1. A method for allocating flow of fluid from first and second pumps to a plurality of hydraulic actuators, said method comprising steps of:

(a) producing a plurality of flow commands, each of which specifies an amount of flow desired to be applied to a different one of the plurality of hydraulic actuators;

(b) for a given one of the plurality of hydraulic actuators;

(1) using all of the plurality of flow commands to determine a first portion of the amount of flow specified by the flow command for the given hydraulic actuator which is to be provided by the first pump and to determine a second portion of the amount of flow specified by the flow command for the given hydraulic actuator which is to be provided by the second pump,

(2) deriving a first flow level in response to the first portion and the flow command for the given hydraulic actuator, and

(3) deriving a second flow level in response to the second portion and the flow command for the given hydraulic actuator;

(c) operating the first pump in response to the first flow level; and

(d) operating the second pump in response to the second flow level.

2. The method as recited in claim 1 wherein deriving a first flow level comprises multiplying the flow command for the given hydraulic actuator by the first portion;

and deriving a second flow level comprises multiplying the flow command for the given hydraulic actuator by the second portion.

3. The method as recited in claim 2 wherein step (b) further comprises operating one valve in response to the first flow level to supply fluid from the first pump to the given one of the plurality of hydraulic actuators, and operating another valve in response to the second flow level to supply fluid from the second pump to the given one of the plurality of hydraulic actuators.

4. The method as recited in claim 1 further comprising repeating step (b) for each of the plurality of hydraulic actuators;

and wherein the first pump is operated in response to the first flow level for all of the plurality of hydraulic actuators and the second pump is operated in response to the second flow level for all of the plurality of hydraulic actuators.

5. The method as recited in claim 4 wherein the first pump is operated in response to a first pump flow command produced by summing all the first flow levels, and the second pump is operated in response to a second pump flow command produced by summing all the second flow levels.

6. The method as recited in claim 4 further comprising:

determining a maximum power level for a prime mover that drives the first and second pumps;

determining a maximum flow level that can be produced by the first and second pumps being driven by the prime mover operating at the maximum power level;

in response to the first flow level and the second flow level for all of the plurality of hydraulic actuators, determining an aggregate flow level required to be produced by the first and second pumps; and

determining whether the aggregate flow level exceeds the maximum flow level.

7. The method as recited in claim 6 further comprising, when the aggregate flow level exceeds the maximum flow level, altering operation of at least one of the first and second pumps so that the aggregate flow level is not greater than the maximum flow level.

8. The method as recited in claim 1 further comprising producing a first pump pressure setpoint for the first pump in response to load forces acting on each of the plurality of hydraulic actuators;

and producing a second pump pressure setpoint for the second pump in response to load forces acting on each of the plurality of hydraulic actuators.

9. The method as recited in claim 1 further comprising:

in step (b) producing a first Function Pressure Setpoint P1 for the first pump in response to the first portion and a load force acting on the given hydraulic actuator, and producing a second Function Pressure Setpoint P2 for the second pump in response to the second portion and the load force;

repeating step (b) for each of the plurality of hydraulic actuators;

producing a first Pump Pressure Setpoint P1 for the first pump in response to the first Function Pressure Setpoints for the plurality of hydraulic actuators; and

producing a second Pump Pressure Setpoint P2 for the second pump in response to the second Function Pressure Setpoints for the plurality of hydraulic actuators.

10. A method for allocating flow of fluid from first and second pumps to a plurality of hydraulic actuators, said method comprising steps of:

(a) producing a plurality of flow commands, each of which specifies an amount of flow desired to be applied to a different one of the plurality of hydraulic actuators;

(b) for a given one the plurality of hydraulic actuators;

(1) determining a proportion of an aggregate maximum flow output of both the first and second pumps that is required to satisfy the amount of flow specified by the flow command for the given hydraulic actuator,

(2) using the proportion of a maximum flow output to determine a first portion of the amount of flow specified by the flow command for the given hydraulic actuator which is to be provided by the first pump and a second portion of the amount of flow specified by the flow command for the given hydraulic actuator which is to be provided by the second pump,

(3) altering the first portion and the second portion in response to the plurality flow commands, thereby producing an altered first portion and an altered second portion for the given hydraulic actuator,

(4) deriving a first flow level in response to the altered first portion and the flow command for the given hydraulic actuator, and deriving a second flow level in response to the altered second portion and the flow command for the given hydraulic actuator; and

(c) repeating step (b) for each of the plurality of hydraulic actuators.

11. The method as recited in claim 10 wherein altering the first portion and the second portion for a given hydraulic actuator comprises altering the first portion by weighted versions of the flow commands for the other hydraulic actuators, and altering the second portion by a weighted versions of the flow commands for the other hydraulic actuators, wherein each flow command for the other hydraulic actuators is weighted based on an amount of influence that the respective hydraulic actuator has on allocation of flow from the first and second pumps.

12. The method as recited in claim 10 wherein deriving a first flow level comprises multiplying the flow command for the given hydraulic actuator by the altered first portion, and deriving a second flow level comprises multiplying the flow command for the given hydraulic actuator by the altered second portion.

13. The method as recited in claim 10 wherein step (b) further comprises operating one valve in response to the first flow level to supply fluid from the first pump to the given one of the plurality of hydraulic actuators, and operating another valve in response to the second flow level to supply fluid from the second pump to the given one of the plurality of hydraulic actuators.

14. The method as recited in claim 10 further comprising:

deriving a first pump flow command in response to all the first flow levels;

operating the first pump in response to the first pump flow command;

deriving a second pump flow command in response to all the second flow levels; and

operating the second pump in response to the second pump flow command.

15. The method as recited in claim 14 wherein the first pump flow command is derived by summing all the first flow levels, and the second flow command is derived by summing all the second flow levels.

16. The method as recited in claim 10 further comprising producing a first pump pressure setpoint for fluid from the first pump in response to load forces acting on each of the plurality of hydraulic actuators;

and producing a second pump pressure setpoint for fluid from the second pump in response to load forces acting on each of the plurality of hydraulic actuators.

17. The method as recited in claim 16 wherein producing a first pump pressure setpoint comprises:

for each of the plurality of hydraulic actuators, producing a function pressure setpoint in response to a load force acting on that hydraulic actuator;

producing a first pump pressure setpoint in response to the function pressure setpoints for those hydraulic actuators which receive fluid from the first pump; and

producing a second pump pressure setpoint in response to the function pressure setpoints for those hydraulic actuators which receive fluid from the second pump.

18. The method as recited in claim 17 wherein producing a first pump pressure setpoint selects a function pressure setpoint having a greatest value, and producing a second pump pressure setpoint selects a function pressure setpoint having a greatest value.

19. The method as recited in claim 17 further comprising controlling pressure of the fluid from the first pump in response to the first pump pressure setpoint;

and controlling pressure of the fluid from the second pump in response to the second pump pressure setpoint.

20. The method as recited in claim 10 further comprising:

determining a maximum power level for a prime mover that drives the first and second pumps;

determining a maximum flow level that can be produced by the first and second pumps being driven by the prime mover operating at the maximum power level;

in response to the first flow level and the second flow level for all the plurality of hydraulic actuators, determining an aggregate flow level desired to be produced by the first and second pumps; and

determining whether the aggregate flow level exceeds the maximum flow level.

21. The method as recited in claim 20 further comprising when the aggregate flow level exceeds the maximum flow level, altering operation of at least one of the first and second pumps so that the aggregate flow level is not greater than the maximum flow level.

22. A method for allocating flow of fluid from first and second pumps to a plurality of hydraulic actuators, said method comprising steps of:

(a) producing a plurality of flow commands, each of which specifies an amount of flow desired to be applied to a different one of the plurality of hydraulic actuators;

(b) for a given one the plurality of hydraulic actuators;

(1) determining a proportion of an aggregate maximum flow output of both the first and second pumps that is required to satisfy the flow command for the given hydraulic actuator,

(2) in response to the proportion of the aggregate maximum flow output, deriving an initial pump bias value denoting an apportionment of flow from the first and second pumps to the given hydraulic actuator, if no other hydraulic actuator is active,

(3) producing a pump bias value by altering the initial pump bias value in response to the plurality flow commands for all the plurality of hydraulic actuators,

(4) in response to the pump bias value, deriving a first proportion of the maximum flow output of the first pump to be applied to the given hydraulic actuator and deriving a second proportion of the maximum flow output of the second pump to be applied to the given hydraulic actuator, and

(5) operating one valve in response to the first proportion and the flow command for the given hydraulic actuator to control fluid flow from the first pump, and operating another valve in response to the second proportion and the flow command for the given hydraulic actuator for the given hydraulic actuator to control fluid flow from the second pump; and

(c) repeating step (b) for each of the plurality of hydraulic actuators.

23. The method as recited in claim 22 wherein deriving an initial pump bias value employs a predefined relationship between the flow command and the amount of flow provided by each of the first and second pumps.

24. The method as recited in claim 22 wherein producing a pump bias value applies a weight factor to each flow command to produce a weighted flow command, and then applies all the weighted flow commands to the initial pump bias value.

25. The method as recited in claim 24 wherein producing a pump bias value further comprises adding the weighted flow commands to the initial pump bias value.

26. The method as recited in claim 22 wherein the one valve is operated in response to a first flow level derived from the first proportion and flow command, and the other valve is operated in response to a second flow level derived from the second proportion and flow command.

27. The method as recited in claim 26 further comprising:

deriving a first pump flow command in response to all the first flow levels;

operating the first pump in response to the first pump flow command;

deriving a second pump flow command in response to all the second flow levels; and

operating the second pump in response to the second pump flow command.

28. The method as recited in claim 27 wherein the first pump flow command is derived by summing all the first flow levels, and the second flow command is derived by summing all the second flow levels.

29. The method as recited in claim 22 further comprising producing a first pump pressure setpoint for the first pump in response to load forces acting on at least some of the plurality of hydraulic actuators;

and producing a second pump pressure setpoint for the second pump in response to load forces acting on at least some of the plurality of hydraulic actuators.

30. The method as recited in claim 29 further comprising operating the first pump in response to the first pump pressure setpoint;

and operating the second pump in response to the second pump pressure setpoint.

31. The method as recited in claim 22 further comprising:

for each given hydraulic actuator, deriving a first flow level from the first proportion and the flow command for that given hydraulic actuator, and deriving a second flow level from the second proportion and flow command for that given hydraulic actuator;

determining a maximum power level for a prime mover that drives the first and second pumps;

determining a maximum flow level that is produced by the first and second pumps being driven by the prime mover operating at the maximum power level;

in response to the first and second flow levels for all the plurality of hydraulic actuators, determining an aggregate flow level desired to be produced by the first and second pumps; and

determining whether the aggregate flow level exceeds the maximum flow level.

32. The method as recited in claim 31 further comprising when the aggregate flow level exceeds the maximum flow level, altering operation of at least one of the first and second pumps so that the aggregate flow level is not greater than the maximum flow level.