Discharge flow control system and method in hydraulic pump

• US 5,659,485 A
• Filed: 04/26/1994
• Issued: 08/19/1997
• Est. Priority Date: 07/02/1993
• Status: Expired due to Fees

• Current Assignee: Volvo Construction Equipment Holding Sweden AB
• Original Assignee: Samsung Heavy Industries Company Limited (Samsung Group)
• Inventors: Lee, Jin-Han
• Primary Examiner(s): Voeltz, Emanuel T.
• Assistant Examiner(s): Smith, Demetra R.
• Application Number:
  US08/233,517
• Time in Patent Office: 1,211 Days
• Field of Search: 60/423, 60/329, 60/431, 60/428, 60/488, 60/487, 244/78, 91/446, 364/510, 364/424.07
• US Class Current: 700/282
• CPC Class Codes: F04B 2201/12051 Angular position
• CPC Class Codes: F04B 2203/0605 Rotational speed
• CPC Class Codes: F04B 2205/05 Pressure after the pump outlet
• CPC Class Codes: F04B 2207/00 External parameters
• CPC Class Codes: F04B 49/065 and making use of computers
• CPC Class Codes: F15B 2211/20546 variable capacity
• CPC Class Codes: F15B 2211/26 Power control functions
• CPC Class Codes: F15B 2211/265 Control of multiple pressure sources
• CPC Class Codes: F15B 2211/633 representing a state of the prime mover, e.g. torque or rotational speed
• CPC Class Codes: G05D 7/0682 using a plurality of flow sources

Abstract

A discharge flow control system and method of a hydraulic pump driven by an engine for the minimization of the difference between a discharge mount of flow in the pump and total mount of operating oil necessary to operate each actuator in hydraulic equipment. The control system is provided with a detector which detects the number of rotation of the engine, generates equal number of pulses to the number of rotation, a detector which detects the tilt angle of a swash plate of the pump, a detector which detects the operating displacement of the actuator, a detector which detects the load pressure acting on the pump, and a controll unit which controls a target discharge flow mount of the pump which is suitable for performing a predetermined work based on the number of rotation, the tilt angle, the displacement and the load pressure.

Claims

1. A system for controlling a discharge flow mount of a hydraulic pump in a hydraulic system having an engine to drive the pump and at least one hydraulic actuator operated by oil flow from the pump, comprising:

means for detecting the number of rotations of the engine, and generating equal number of pulses to the number of rotations;

means for detecting the tilt angle of a swash plate of the pump;

means for detecting directly the operating displacement of the actuator;

means for detecting the load pressure acting on the pump; and

means for controlling a target discharge flow mount of the pump which is suitable for performing a predetermined work based on the number of rotations, the tilt angle, the displacement and the bad pressure.

2. The system according to claim 1, wherein the control means comprises:

a central processing unit;

at least one means for converting analog signals from the tilt angle detecting means, the operating displacement detecting means, and the load pressure detecting means into digital signals;

a means for selecting one of the output digital signals from the A/D converter;

a means for counting the number of the output pulses of the rotation detecting means;

a means for storing a control program to be performed by the central processing unit;

at least one means for converting the output digital signals into analog signals; and

at least one means for amplifying the output analog signals and for providing the amplified analog signals as control signals for the pump.

3. A method for controlling a discharge flow mount of a hydraulic pump in a hydraulic system having an engine to drive the pump and at least one hydraulic actuator operated by oil flow from the pump, comprising steps of:

calculating a required flow mount of the actuators needed to perform a predetermined operation;

calculating a dischargeable flow mount of the pump based on a load pressure acting thereto;

calculating a required discharge flow mount of the pump needed to perform the predetermined operation;

reading the number of rotations of the engine, the tilt angle of a swash plate of the pump, and the operating displacement of the actuator;

calculating an actual discharge flow mount of the pump based on the number of rotations, the tilt angle and the operating displacement;

calculating an actual flow mount provided from the pump to the actuator;

calculating a difference between the required and the actual actual discharge flow mounts of the pump, and another difference between the required and the actual flow mounts of the actuator;

calculating a target discharge flow amount of the pump which is suitable for performing the predetermined operating based on the relation of the two differences; and

converting the target discharge flow mount into a voltage signal for use as a control signal in the hydraulic system.