Axial piston pump controller

Patent metadata

Field	Value
Publication number	US-11933290-B2
Application number	US-202217886693-A
Country	US
Kind code	B2
Filing date	Aug 12, 2022
Priority date	Aug 12, 2021
Publication date	Mar 19, 2024
Grant date	Mar 19, 2024

Abstract

An axial piston pump controller for an axial piston pump having a fixed valve plate and a variable displacement is provided. The axial piston pump controller is configured to determine a displacement of the axial piston pump, and to calculate a pump displacement control current to be supplied to the axial piston pump to control the displacement of the axial piston pump. Calculating the pump displacement control current comprises calculating a nominal value for the pump displacement control current based on a rotational speed of the axial piston pump, calculating a pump stiffness adjustment factor based on a pump stiffness control map having as inputs: an output pressure of the axial piston pump; and the estimated pump displacement, and calculating the pump displacement control current to be supplied to the axial piston pump based on the nominal value and the pump stiffness adjustment factor. The controller is further configured to output an instruction to output the calculated pump displacement control current to the axial piston pump in order to control the displacement of the axial piston pump.

First claim

What is claimed is:

1. An axial piston pump controller for an axial piston pump having a fixed valve plate and a variable displacement configured to:
determine a displacement of the axial piston pump;
calculate a pump displacement control current to be supplied to the axial piston pump to control the displacement of the axial piston pump comprising:
calculating a nominal value for the pump displacement control current based on a rotational speed of the axial piston pump;
calculating a pump stiffness adjustment factor based on a pump stiffness control map having as inputs: an output pressure of the axial piston pump; and the estimated pump displacement; and
calculating the pump displacement control current to be supplied to the axial piston pump based on the nominal value and the pump stiffness adjustment factor; and

output an instruction to output the calculated pump displacement control current to the axial piston pump in order to control the displacement of the axial piston pump.

2. An axial piston pump controller according to claim 1 , wherein
the axial piston pump to be controlled comprises a control cylinder connected to the swash plate and configured to control the angle of inclination of the swash plate; and
a valve configured to control a flow of hydraulic fluid to the control cylinder, wherein a position of the valve is controlled by a solenoid actuator, wherein the pump displacement control current calculated by the controller is output to the solenoid actuator.

3. An axial piston pump controller according to claim 1 , wherein
in order to determine the displacement of the axial piston pump, the controller is configured to:
calculate an estimated displacement based on a displacement

estimation control map having as inputs: the rotational speed of the axial piston pump and a variable representative of a flow rate of hydraulic fluid to the control cylinder.

4. An axial piston pump controller according to claim 1 , wherein
a plurality of pump stiffness control maps are provided, each of the plurality of pump stiffness control maps corresponding to a different rotational speed of the axial piston pump,
wherein the controller is configured to select one of the plurality of pump stiffness control maps to calculate the pump stiffness adjustment factor based on the rotational speed of the axial piston pump.

5. An axial piston pump according to claim 4 , wherein
each of the plurality of pump stiffness control maps defines a different relationship between the inputs: output pressure of the axial piston pump and the estimated pump displacement, and the output pump stiffness adjustment factor.

6. An axial piston pump controller according to claim 4 , wherein
each of the plurality of pump stiffness control maps incorporates the nominal value for the pump displacement control current based on the rotational speed for the respective pump stiffness control map into the output of the respective pump displacement control map.

7. An axial piston pump having a fixed valve plate and a variable displacement comprising:
a swash plate having a variable angle of inclination in order to define a displacement of the axial piston pump;
a solenoid actuator connected to the swash plate, the solenoid actuator configured to control the angle of inclination of the swash plate in order to control the displacement of the axial piston pump; and
an axial piston pump controller configured to:
determine a displacement of the axial piston pump;
calculate a pump displacement control current to be supplied to the solenoid actuator to control the displacement of the axial piston pump comprising:
calculating a nominal value for the pump displacement control current based on a rotational speed of the axial piston pump;
calculating a pump stiffness adjustment factor based on a control map having as inputs: an output pressure of the axial piston pump; and the estimated pump displacement; and
calculating the pump displacement control current to be supplied to the solenoid actuator based on the nominal value and the pump stiffness adjustment factor; and

output an instruction to output the calculated pump displacement control current to the solenoid actuator in order to control the displacement of the axial piston pump.

8. An axial piston pump according to claim 7 , further comprising:
a control cylinder connected to the swash plate and configured to control the angle of inclination of the swash plate; and
a valve configured to control a low of hydraulic fluid to the control cylinder, wherein a position of the valve is controlled by the solenoid actuator.

9. An axial piston pump according to claim 7 , wherein
in order to determine the displacement of the axial piston pump, the controller is configured to:
calculate an estimated displacement based on a displacement estimation control map having as inputs: the rotational speed of the axial piston pump and a variable representative of a flow rate of hydraulic fluid to control cylinder.

10. An axial piston pump according to claim 7 , wherein
a plurality of pump stiffness control maps are provided, each of the plurality of pump stiffness control maps corresponding to a different rotational speed of the axial piston pump,
wherein the controller is configured to select one of the plurality of pump stiffness control maps to calculate the pump stiffness adjustment factor based on the rotational speed of the axial piston pump.

11. An axial piston pump according to claim 10 , wherein
each of the plurality of pump stiffness control maps defines a different relationship between the inputs: output pressure of the axial piston pump and the estimated pump displacement, and the output pump stiffness adjustment factor.

12. An axial piston pump controller according to claim 10 , wherein
each of the plurality of pump stiffness control maps incorporates the nominal value for the pump displacement control current based on the rotational speed for the respective pump stiffness control map into the output of the respective pump displacement control map.

13. A method of controlling a displacement of an axial piston pump having a fixed valve plate and a variable displacement comprising:
estimating a displacement of the axial piston pump;
calculating a pump displacement control current to be supplied to the axial piston pump to control the displacement of the axial piston pump comprising:
calculating a nominal value for the pump displacement control current based on a rotational speed of the axial piston pump;
calculating a pump stiffness adjustment factor based on a pump stiffness control map having as inputs: an output pressure of the axial piston pump; and the estimated pump displacement; and
calculating the pump displacement control current to be supplied to the axial piston pump based on the nominal value and the pump stiffness adjustment factor; and

outputting an instruction to output the calculated pump displacement control current to the axial piston pump in order to control the displacement of the axial piston pump.

14. A method according to claim 13 , wherein
a plurality of pump stiffness control maps are provided, each of the plurality of pump stiffness control maps corresponding to a different rotational speed of the axial piston pump,
wherein the controller is configured to select one of the plurality of pump stiffness control maps to calculate the pump stiffness adjustment factor based on the rotational speed of the axial piston pump.

15. A method according to claim 14 , wherein
each of the plurality of pump stiffness control maps defines a different r

Assignees

• Caterpillar Inc

Inventors

• Bakken Arick
• Cairns Paul John
• Swick William Christopher

Classifications

• F04B49/065 Primary

  and making use of computers · CPC title

• F04B1/146

  Swash plates; Actuating elements · CPC title

• F04B1/188

  Plate-like distribution members · CPC title

• F04B1/324 Primary

  by changing the inclination of the swash plate · CPC title

• F04B49/12

  by varying the length of stroke of the working members · CPC title