JP-7856486-B2 - Calibration system in hydraulic systems

Inventors

• 中嶌 秀樹
• 喜安 浩一
• 古賀 寿和

Assignees

• キャタピラー エス エー アール エル

Dates

Publication Date

20260511

Application Date

20220527

Claims (1)

1. In a hydraulic system for a work machine comprising a hydraulic actuator, a control valve for controlling the flow rate supplied to the hydraulic actuator, an operating tool for driving the hydraulic actuator, and control means for controlling the control valve based on the operation of the operating tool, when performing calibration to set the correspondence between the amount of operation of the operating tool and the flow rate supplied to the hydraulic actuator to a preset relationship, The control valve comprises a spool valve that opens a supply opening to a hydraulic actuator with an opening area corresponding to the input pilot pressure, a pressure compensation valve that maintains a constant differential pressure across the supply opening of the spool valve, and an electromagnetic proportional valve that outputs a pilot pressure to the spool valve corresponding to the current value output from the control means. The control means includes correspondence data between the amount of operation of the operating tool and the output current value to the electromagnetic proportional valve, and controls the control valve by outputting a current value corresponding to the amount of operation of the operating tool to the electromagnetic proportional valve based on this correspondence data, The configuration is such that calibration is performed using measured data to determine the correspondence between the output pilot pressure from the electromagnetic proportional valve and the supply flow rate output from the control valve, before the control valve is mounted on the work machine. The calibration system that performs the calibration, A pressure detection means for detecting the output pilot pressure from the solenoid proportional valve to the spool valve, An output current control means that outputs current to the electromagnetic proportional valve when calibration is performed, A calibration system for a hydraulic system, characterized by comprising: a calibration means that sets the output pilot pressure from the electromagnetic proportional valve in the measured data when the supply flow rate corresponds to the amount of operation of the calibration point's operating tool according to the preset setting relationship, as the target pilot pressure, and the output current value from the output current control means to the electromagnetic proportional valve when the pilot pressure detected by the pressure detection means becomes the target pilot pressure, as the output current value corresponding to the amount of operation of the calibration point's operating tool, thereby calibrating the corresponding data.

Description

This invention relates to the technical field of calibration systems in hydraulic systems for work machines such as hydraulic excavators. Generally, hydraulic systems in work machines such as hydraulic excavators are equipped with control valves that control the supply and discharge of oil to various hydraulic actuators. Some of these control valves consist of an electromagnetic proportional pressure reducing valve, which is operated by a control signal output from a controller based on the operation of a hydraulic actuator operating tool, and a spool valve, which controls the flow rate by being operated by the pilot pressure output from the electromagnetic proportional valve. However, when controlling the supply flow rate to a hydraulic actuator with a control valve consisting of such an electromagnetic proportional pressure reducing valve and spool valve, variations may occur in the correspondence between the amount of operation of the operating tool and the flow rate supplied from the control valve to the hydraulic actuator due to manufacturing tolerances of the electromagnetic proportional pressure reducing valve, etc. This can lead to differences in the operating speed of the hydraulic actuator from machine to machine, even with the same amount of operation of the operating tool, potentially compromising the uniformity of operation. To avoid this, calibration is required to set the relationship between the amount of operation of the operating tool and the supply flow rate to a predetermined setting. Conventionally, a technique has been known in which a control valve is equipped with an on/off valve structure that has a passage open position and a passage closed position set in relation to the stroke of the spool valve, and the input current value to the electromagnetic proportional valve when the pressure in the measurement passage passing through the on/off valve structure is determined, thereby determining the measured characteristics of the input current to the electromagnetic proportional valve and the stroke of the spool valve, and calibrating the reference characteristics based on these measured characteristics (see, for example, Patent Document 1). Japanese Patent Publication No. 2007-278490 This is a hydraulic circuit diagram showing a part of the hydraulic system of a work machine.This figure shows the relationship between the output pilot pressure from the solenoid proportional valve and the opening area of the supply opening of the spool valve.This is a flowchart illustrating the calibration procedure.Tables and diagrams illustrating specific examples of each data point. Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 shows a part of a hydraulic system installed in a work machine such as a hydraulic excavator. In Figure 1, 1 is an on-board controller (corresponding to the control means of the present invention), 2 is a hydraulic pump, 3 is a solenoid proportional valve for the pump that operates based on a control signal from the controller 1 to vary the capacity of the hydraulic pump 2, 4 is an oil tank, 5 is a hydraulic actuator that uses the hydraulic pump 2 as a hydraulic power source, 6 is a control valve that controls the supply and discharge of the hydraulic actuator 5 based on a control signal from the controller 1, and 7 is an operating device (such as an operating lever or pedal) that is operated to drive the hydraulic actuator 5. In this embodiment, the hydraulic actuator 5 is a bidirectional rotating motor or a double-acting cylinder, with pressurized oil supplied in both directions. By operating the operating tool 7 to one side, pressurized oil is supplied in one direction, and by operating it to the other side, pressurized oil is supplied in the other direction. Furthermore, for example, if the work machine is a hydraulic excavator, the hydraulic excavator is equipped with various hydraulic actuators such as a boom cylinder, stick cylinder, bucket cylinder, travel motor, swing motor, and hydraulic actuator for optional attachments, as well as control valves and operating tools for each hydraulic actuator. However, Figure 1 shows only one hydraulic actuator 5, control valve 6, and operating tool 7 that are the subject of the present invention. The control valve 6 comprises a pilot-operated spool valve 8 (described later), a pressure compensation valve 9 located upstream of the spool valve 8, and first and second solenoid proportional valves 10A and 10B that output pilot pressure to the spool valve 8. The spool valve 8 is a directional control valve that controls the supply and discharge flow rates to the hydraulic actuator 5 and switches the supply and discharge direction, and includes first and second pilot ports 8a and 8b connected to first and second solenoid proportional valves 10A and 10B, respectively, a pump port 8p connected to the hydraulic pump 2 via a pressure compensation valve 9, a tank port 8t connected t