Method of controlling the flow rate of a variable capacity hydraulic pump for a construction apparatus

Patent metadata

Field	Value
Publication number	US-9303659-B2
Application number	US-201013994857-A
Country	US
Kind code	B2
Filing date	Dec 28, 2010
Priority date	Dec 28, 2010
Publication date	Apr 5, 2016
Grant date	Apr 5, 2016

Abstract

Disclosed is a method of controlling the flow rate of a hydraulic pump, which controls the discharge flow rate in proportion to a manipulated amount of a manipulation lever operated by a user even when the discharge pressure of the hydraulic pump is varied. The method of controlling the flow rate of a variable capacity hydraulic pump for a construction apparatus according to the present invention includes: a first step of calculating the required flow rate of the variable capacity hydraulic pump according to a manipulated amount of a manipulation lever operated by a user; a second step of calculating the maximum discharge flow rate within a range equal to or less than a preset horsepower or torque of the variable capacity hydraulic pump corresponding to the pressure detected by a discharge pressure detecting sensor; and a third step of controlling the discharge flow rate of the variable capacity hydraulic pump in proportion to a manipulated amount of the manipulation lever within a range equal to or less than the maximum discharge flow rate set in the second step.

First claim

The invention claimed is:

1. A method of controlling a flow rate of a variable displacement hydraulic pump for a construction machine which comprises: a variable displacement hydraulic pump, a hydraulic actuator connected to the hydraulic pump, a manipulation lever configured to output a manipulation signal that is in proportion to a manipulation amount of the manipulation lever by a user, a control valve configured to control a start, a stop, and a direction change of the hydraulic actuator when it is shifted in response to the manipulation signal outputted from the manipulation lever, a manipulation amount detector configured to detect the manipulation amount of the manipulation lever and electrically connected to a controller, a discharge pressure detection sensor configured to detect a pressure of a hydraulic fluid discharged from the hydraulic pump, and a controller configured to control a discharge flow rate of the hydraulic pump in response to detection signals outputted from the manipulation amount detection detector and the discharge pressure detection sensor, the method comprising:
a first step of calculating a discharge flow rate of the hydraulic fluid, which is required by the hydraulic pump according to the manipulation amount of the manipulation lever by a user;
a second step of calculating an allowable discharge flow rate within a range that does not exceed a preset specific horsepower or torque of the hydraulic pump, relative to the discharge pressure of the hydraulic fluid detected by the discharge pressure detection sensor; and
a third step of controlling a discharge flow rate of the hydraulic pump in proportion to the manipulation amount of the manipulation lever within a range of the allowable discharge flow rate value calculated in the second step;
wherein the discharge flow rate of the hydraulic pump is calculated by calculating the discharge flow rate required by the hydraulic pump according to the manipulation amount of the manipulation lever as a percentage under the no-load condition and multiplying the allowable discharge flow rate of the hydraulic pump relative to the preset discharge pressure by the calculated percentage.

2. The method according to claim 1 , wherein in the third step, if the manipulation amount of the manipulation lever requires a maximum pump flow rate under a no-load condition, the discharge flow rate of the hydraulic pump is controlled to be a maximum dischargeable flow rate of the hydraulic pump relative to a preset discharge pressure.

3. A method for controlling a flow rate of a variable displacement hydraulic pump for actuating a boom arm of an excavator comprising;
detecting with a pilot pressure detection sensor a manipulation signal output from a manipulation lever moved by a user to move the boom arm;
generating with the pilot pressure detection sensor a manipulation amount detection signal for application to a controller configured to control the variable displacement hydraulic pump;
calculating with the controller a discharge flow rate (Q 1 ) required by the variable displacement hydraulic pump according to a manipulation amount that the user moves the manipulation lever based on a relationship between the manipulation amount of the manipulation lever and a volume of the hydraulic pump;
detecting discharge pressure of the hydraulic pump with a discharge pressure detection sensor, which generates a discharge pressure detection signal that is sent to the controller;
calculating an allowable discharge flow rate (Q allowable ) of the hydraulic pump within a range that does not exceed a preset specific horsepower or torque of the hydraulic pump, relative to the discharge pressure of hydraulic fluid detected by the discharge pressure detection sensor; and
controlling a discharge flow rate (Q) of the hydraulic pump in proportion to the manipulation amount of the manipulation lever within a range of the allowable discharge flow rate value (Q allowable );
wherein:
if the manipulation amount of the manipulation lever is a maximum amount, the discharge flow rate Q of the hydraulic pump is controlled to be a maximum dischargeable flow rate Qmax of the hydraulic pump relative to a preset discharge pressure;
the discharge flow rate Q of the hydraulic pump is calculated by calculating the discharge flow rate Q 1 required by the hydraulic pump according to the manipulation amount of the manipulation lever as a percentage (Q 1 /Qmax) under a no-load condition and multiplying the allowable discharge flow rate (Q allowable ) of the hydraulic pump relative to the preset discharge pressure by the calculated percentage Q 1 /Qmax; and
the discharge flow rate Q of the hydraulic pump for actuating the boom arm of the excavator is calculated using the following equation: Q=Q allowable ×(Q 1 /Qmax).

Assignees

• Shin Hung-Ju
• Volvo Constr Equip Ab

Inventors

• Shin Hung-Ju

Classifications

• F15B2211/6652

  Control of the pressure source, e.g. control of the swash plate angle · CPC title

• F15B2211/20546

  variable capacity · CPC title

• E02F9/2296

  Systems with a variable displacement pump · CPC title

• F15B2211/6654

  Flow rate control · CPC title

• F15B2211/255

  Flow control functions · CPC title