JPH02134404A - Hydraulic circuit with feedback circuit - Google Patents

Abstract

PURPOSE:To improve controllability by making a controller compensate the value of a current being inputted into a magnet proportional control valve so as to recover a delay of up and down of pilot hydraulic pressure on the basis of signal voltage subjected to feedback, in a hydraulic circuit for farm working machinery or the like. CONSTITUTION:When an opening lever 1 is moved out of its neutral position, the displacement is detected by a potentiometer, inputting signal voltage into a controller 3, and an electric current conformed to magnitude of the signal voltage is transmitted to a magnet selector control valve 4 or 5. Now, supposing that the current is inputted into a magnet proportional control valve 5, pressure oil acts on a main valve 7 by way of this magnet proportional valve 5 and a pilot circuit 5a, but there is a time lag in movement of the magnet proportional control valve 5 to displacement of the operating lever 1, so that a rise in pilot hydraulic pressure comes slow. Accordingly, it is inputted into the controller 3 from a pressure sensor 9, whereby the controller 3 further inputs a large current into the magnet proportional control valve 5, accelerating its movement, thus the pilot hydraulic pressure is raised up in the wake of displacement of the operating lever 1.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a hydraulic circuit for hydraulic equipment, and in particular to a hydraulic circuit having a main circuit and a pilot circuit in hydraulic equipment used for construction machinery, etc. .

[Prior Art] Conventionally, in construction machinery, etc., the hydraulic circuit that operates the work equipment includes a main hydraulic circuit that sends pressure oil discharged from a hydraulic pump to an actuator via an operating valve, and a main hydraulic circuit that controls the movement of an operating lever. Many models are equipped with a pilot hydraulic circuit that transmits information to the valve, but as a switching/control valve for the pilot hydraulic pressure, the amount of displacement of the operating lever is input to the controller as an electrical signal, and based on this, the controller outputs a current. There is one that uses an electromagnetic proportional control valve that is operated by.

[Problems to be Solved by the Invention] However, when the above electromagnetic proportional control valve is used in an oven circuit, when the operating lever is moved from the neutral position, a current proportional to the amount of displacement of the operating lever acts on the electromagnetic proportional control valve. As a result, the operation of the electromagnetic proportional control valve is delayed with respect to the current rising curve shown by the chain line in Figure 2, and the pilot oil pressure rise curve becomes gradual as shown by the chain line in Figure 3, causing the hydraulic system to Responsiveness deteriorates.

In addition, due to hysteresis of the electromagnetic proportional control valve, a difference occurs in the pilot oil pressure when the current increases and decreases, as shown by the chain line in Figure 4, or due to variations in the electromagnetic valve, as shown in Figure 5, a difference occurs in the pilot oil pressure when the current increases. There is a problem in that the fluctuation range p of the pilot oil pressure with respect to the size becomes large, resulting in a poor operating feel.

The present invention has focused on the above-mentioned conventional problems, and an object of the present invention is to provide a hydraulic circuit in which an electromagnetic proportional control valve operates in a manner that faithfully follows the displacement amount of an operating lever without delay.

[Means for Solving the Problems] In order to achieve the above object, a hydraulic circuit having a feedback circuit according to the present invention inputs the amount of displacement of the operating lever as a signal voltage to a controller, and the controller inputs the displacement amount to the signal voltage. In a hydraulic circuit having a pilot circuit from an electromagnetic proportional control valve operated by outputting a corresponding current to both ends of the main valve, and a main circuit from the main pump to the actuator via the main valve, the hydraulic pressure of the pilot circuit is A feedback circuit is provided from the pressure sensor to the controller, and based on the feedback signal voltage, the controller corrects the value of the current input to the electromagnetic proportional control valve to recover from the delay in the rise or fall of the pilot oil pressure. It was configured to do this.

[Operation] According to the above configuration, the pressure sensor detects the oil pressure in the pilot circuit and feeds it back to the controller, and the controller corrects the output current value based on the result, so the operation of the electromagnetic proportional control valve is can now fully follow the movement of the operating lever, improving the responsiveness and operating feel of hydraulic equipment.

[Example] Below, an example of a hydraulic circuit having a feedback circuit according to the present invention will be described in detail with reference to the drawings.

In FIG. 1, a potentiometer 2 for detecting the amount of displacement of the operating lever 1 is connected to a controller 3, which in turn is connected to an electromagnetic proportional control valve 4.5. The hydraulic circuits 6a and 6b of the control pump 6 are connected to the electromagnetic proportional control valve 4.5, and the pilot circuits 4a and 5a from the electromagnetic proportional control valves 4 and 5 to both ends of the main valve 7 are provided with hydraulic pressure outlets. Sensors 8 and 9 are installed, and the wires of the pressure sensors 8 and 9 are connected to the controller 3.

When the control lever 1 is moved from the neutral position, the amount of displacement of the control lever 1 is detected by the potentiometer 2, and a signal voltage is input to the controller 3. The controller 3 transmits a current depending on the magnitude of the input signal voltage to the electromagnetic proportional control valve 4 or 5.

Assuming that current is input to the electromagnetic proportional control valve 5, the solenoid of the electromagnetic proportional control valve 5 is excited and operates, and the pressure oil from the control pump 6 passes through the electromagnetic proportional control valve 5 and the pilot circuit 5a to the main flow. It acts on the left end of valve 7,
At this time, the pressure sensor 9 detects the oil pressure of the pilot circuit 5a and feeds it back to the controller 3.

As mentioned above, since there is a delay in the movement of the electromagnetic proportional control valve 5 with respect to the amount of displacement of the operating lever 1, the increase in pilot oil pressure is delayed, and this is input to the controller 3 from the pressure sensor 9, so that the controller 3 A larger current is input to the electromagnetic proportional control valve 5. In other words, as shown by the solid line in Figure 2, a current larger than the current proportional to the displacement of the operating lever 1 flows, and when the operating lever l is moved to the end of its stroke, Io + α is input to the rated current 1o. , the movement of the electromagnetic proportional control valve 5 is accelerated,
The pilot oil pressure is operated as shown by the solid line in FIG. 3, rising to follow the displacement of the bar l, pushing the main valve 7 to the right and sending pressure oil from the main pump lO to the actuator 11.

Furthermore, the pressure sensors 8 and 9 feed back the oil pressure data of the pilot circuit to the controller 3, so that the problem caused by hysteresis of the electromagnetic proportional control valve is resolved as shown by the solid line in FIG. Further, the problem caused by variations in the electromagnetic proportional control valve is solved by reducing p in FIG. 5 to a level that does not pose a practical problem.

[Effects of the Invention] As explained above, according to the present invention, the oil pressure data of the pilot circuit is fed back to the controller so that the controller corrects the excitation current of the electromagnetic proportional control valve. can now sufficiently follow the movement of the operating lever, significantly improving the responsiveness and operating feel of hydraulic equipment, and making it easier to operate work equipment.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a hydraulic circuit having a feedback circuit according to the embodiment, Fig. 2 is a graph of the current input to the electromagnetic proportional control valve versus time when the operating lever is moved, and Fig. 3 is a graph of the current input to the electromagnetic proportional control valve versus time when the operating lever is moved. Graphs of oil pressure; FIG. 4 is a graph showing the relationship between current and pilot oil pressure related to hysteresis of the electromagnetic proportional control valve; FIG. 5 is a graph showing the relationship between current and pilot oil pressure related to variations in the electromagnetic proportional control valve. 1...Operating lever 3...Controller 4.5...Solenoid proportional control valves 4a, 5a...◆Pilot circuit 7...
Main valve 8.9...Pressure sensor 10...Main pump 11...Actuator Patent applicant Komatsu Ltd.

Claims (1)

[Claims] A pilot circuit extending from an electromagnetic proportional control valve to both ends of the main valve, which operates by inputting the amount of displacement of the operating lever as a signal voltage to a controller and outputting a current according to the signal voltage, and the main pump. In a hydraulic circuit having a main circuit extending from the main circuit to the actuator via the main valve, a feedback circuit is provided from a pressure sensor that detects the hydraulic pressure of the pilot circuit to the controller, and the controller performs electromagnetic proportional control based on the feedback signal voltage. A hydraulic circuit having a feedback circuit characterized in that the value of the current input to the valve is corrected so as to recover from a delay in the rise or fall of pilot oil pressure.