Electronic torque and pressure control for load sensing pumps

Patent metadata

Field	Value
Publication number	US-2016363117-A1
Application number	US-201515120900-A
Country	US
Kind code	A1
Filing date	Mar 18, 2015
Priority date	Mar 20, 2014
Publication date	Dec 15, 2016
Grant date	—

Abstract

A pump control system, comprising: a motor ( 12 ) configured to drive a pump ( 14 ); a pressure relief valve ( 22 ) in fluid communication with the pump ( 14 ); a torque control valve ( 32 ) connected to a swashplate of the pump ( 14 ) and in fluid communication with the pressure relief valve ( 22 ); a swashplate angle sensor ( 36 ) connected to the swashplate ( 34 ); and a computer ( 40 ) connected to the swashplate angle sensor ( 36 ) and the pressure relief valve ( 22 ) wherein the computer ( 40 ) controls the pressure relief valve ( 22 ) based upon swashplate displacement to achieve maximum system pressure. The corresponding method of controlling is also disclosed.

First claim

What is claimed:

1 . A pump control system, comprising:
a motor configured to drive a pump; a pressure relief valve in fluid communication with the pump; a torque control valve connected to a swashplate of the pump and in fluid communication with the pressure relief valve; a swashplate angle sensor connected to the swashplate; and a computer connected to the swashplate angle sensor and the pressure relief valve wherein the computer controls the pressure relief valve based upon swashplate displacement to achieve maximum system pressure.

2 . The system of claim 1 wherein the computer calculates a maximum pressure that would result in a torque level produced at a given swash plate displacement.

3 . The system of claim 2 wherein the computer sends a signal to the pressure relief valve providing a current to achieve the maximum pressure.

4 . The system of claim 1 further comprising a pressure transducer that monitors a pressure required for a lift function.

5 . The system of claim 1 further comprising a dump valve to reduce a set point of the pump engine cranking.

6 . The system of claim 1 wherein the computer pulls back a command of at least a first function when a command is issued for a second function and a torque set point of the pump does not allow a load to be lifted until pump displacement is decreased to a point that will have a high enough pressure to lift the load on the second function.

7 . The system of claim 6 wherein a pressure transducer monitors pressure required for function 2.

8 . A method of controlling a load sensing pump, comprising the steps of:
monitoring an angle of a swashplate with a swashplate angle sensor and software of a micro-controller; calculating with the software a maximum pressure resulting in a torque level that an engine could produce at a given displacement; and sending a correct current to a proportional pressure relief valve to achieve maximum pressure.

9 . The method of claim 8 further comprising the step of monitoring a pressure required to lift a load with a pressure transducer.

10 . The method of claim 9 further comprising the step of decreasing a pump displacement to a point that provides high enough pressure to lift the load when a torque set point does not allow the load to be lifted.

11 . The method of claim 8 further comprising the step of reducing a pressure set point for the pump during cranking to reduce outlet pressure, displacement, and a load on an engine's starter.

12 . The method of claim 8 further comprising the step of limiting control valve opening so that a torque limiter is not impacted by margin erosion.

13 . The method of claim 8 wherein as high pressure de-strokes a pump the computer causes LS pressure to increase until a desired difference between pump output and LS pressure is reached.

14 . A pump control system, comprising:
a pump having a swashplate; a pressure relief valve in fluid communication with the pump; a swashplate angle sensor connected to the swashplate; and a computer connected to the pressure relief valve and the swashplate angle sensor that controls the pressure relief valve based upon swashplate angle.

Assignees

• Danfoss Power Solutions Inc

Inventors

• Ligenfelter Kevin
• Lafayette Gary

Classifications

• F04B1/295

  by changing the inclination of the swash plate · CPC title

• F04B1/324

  by changing the inclination of the swash plate · CPC title

• F04B49/065 Primary

  and making use of computers · CPC title

• F04B49/12

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