JPH0721282B2 - Variable displacement pump - Google Patents

Description

The present invention relates to a variable displacement pump.

[Conventional technology]

In the variable displacement pump, a method of using a proportional solenoid control valve is conventionally known to control the discharge flow rate and the discharge pressure. In the general conventional method, a proportional electromagnetic relief valve is used to control the discharge pressure, and hydraulic pressure feedback control is performed to achieve a set pressure according to the input current, and the discharge flow rate is controlled by another proportional electromagnetic control valve. The displacement of the variable discharge amount element is controlled.

In such a conventional variable displacement pump, since the proportional solenoid control valve is separately prepared and used for controlling the pressure and the flow rate, not only the control valve but also the current amplifier for driving them are separately provided. Therefore, it was inevitable that the device would become large and the power consumption would increase. In the conventional variable displacement pump, when the rotation speed changes due to changes in the slip amount of the pump drive motor due to load fluctuations, etc., it appears as changes in the pump discharge amount, and the volumetric efficiency of the pump changes due to increases in load pressure. Also appears as a change in the discharge amount, and if there is a change in viscosity due to a change in hydraulic oil temperature, this also appears as a change in the discharge amount. There are various types and they are particularly problematic when precise control is required.

[Problems to be solved by the invention]

The problem to be solved by the present invention is that a single proportional solenoid control valve controls both pressure and flow rate by a closed loop feedback control system including a hydraulic system, and a dynamic correction for each of the fluctuation factors is performed in this loop. It is possible to exert characteristics suitable for precise control by applying
It is an object of the present invention to provide a variable displacement pump capable of monitoring the level of fluctuation factors and giving an alarm in advance for an abnormality of equipment.

[Means for solving problems]

According to the present invention, the displacement of the variable element is controlled against the spring force by controlling the hydraulic pressure in the pressurizing chamber of the variable discharge amount element by the proportional solenoid control valve, and the range from the maximum discharge amount to the full cutoff is controlled. In a variable displacement pump in which the discharge amount is variable inside, a flow rate detecting means for generating an electric signal corresponding to the discharge amount of the pump, a pressure detecting means for generating an electric signal corresponding to the pump discharge pressure, a flow rate setting signal and the above-mentioned The drive control current supplied to the proportional electromagnetic control valve is controlled according to the deviation from the output signal of the flow rate detecting means, and when the detected pump discharge pressure reaches a set value, a pressure setting signal and the pressure detecting means Control means for controlling the drive control current based on the deviation from the output signal, and pump operation of pump discharge pressure, actuator operating speed, pump rotational speed, or pump operating oil temperature. And a data detection means for detecting the variation data, said control means has a correction function to apply a correction corresponding to the magnitude of the variation data to the drive control current by the detection output of the data detecting means.

In a preferred embodiment of the present invention, the data detection means includes abnormality detection means for monitoring the magnitude of its own detection output and outputting an alarm signal when it exceeds a predetermined upper limit value. I'm out.

[Action]

In the present invention, with respect to the control of the drive control current of the proportional solenoid control valve that hydraulically controls the displacement of the pump discharge amount variable element,
For example, the flow rate feedback signal is obtained from the displacement amount of the discharge amount variable element of the pump to obtain the deviation from the set value, and the discharge flow rate is feedback-controlled by the electro-hydraulic closed loop.
Discharge pressure detected by a pressure sensor, etc. is matched with the pressure set value to perform cut-off control with an electro-hydraulic closed loop. Furthermore, fluctuation data of pump discharge pressure, actuator operating speed, pump rotational speed, or pump operating oil temperature during pump operation. Is detected by the data detecting means, and the correction function of the control means corrects the drive control current controlled by the closed loop control system by the detection output of the data detecting means according to the magnitude of the fluctuation data. It is possible to realize a closed loop precision control including almost all of the above in a loop and to provide a failure prediction / diagnosis function such as an abnormality of equipment by using the detected variation data.

〔Example〕

The drawing is a circuit diagram showing the overall configuration of the system of the variable displacement pump according to the embodiment of the present invention. The pump element 2 connected to the rotary shaft of the electric motor 1 changes the discharge flow rate by the displacement of the discharge rate variable element 3. Change. The hydraulic system for controlling the discharge amount includes a proportional electromagnetic control valve 4 for controlling the oil pressure in the pressurizing chamber in order to displace the variable element 3 against the spring force, and when the discharge pressure reaches a set upper limit. And a safety valve 5 for displacing the variable element 3 regardless of the proportional electromagnetic control valve 4 to bring the pump into a full cutoff state.

This variable displacement pump further includes a pressure sensor 6 for detecting the discharge pressure of the pump, and a displacement detector 7 for detecting the amount of displacement of the variable element 3 as a detection amount corresponding to the discharge flow rate of the pump.
And a control device 9 for supplying a drive control current corresponding to set values of pressure and flow rate, which form a feedback loop with these sensors and detectors, to the solenoid device 8 of the control valve 4.

The controller 9 has a pressure setting signal input terminal 10 and a flow rate setting signal input terminal 11, and also has a function of correcting the drive control current based on the fluctuation data detection value described below.

The actuator control valve device 12, such as a directional control valve connected to the pump discharge line, is symbolically shown here as a block. A cylinder 13 and a hydraulic motor 14 are shown in the figure as actuators whose speed and torque are controlled by the pump discharge oil via the control valve device 12.

15 is a rotation speed detector for detecting the rotation speed of the electric motor 1, 16
Is a temperature detector that detects the oil temperature of the pump, 17 is the cylinder 13
Is a speed detector for detecting the speed of the hydraulic motor 14, 18 is a speed detector for detecting the speed of the hydraulic motor 14, and each of the fluctuation data of the system is dynamically detected by these detectors during operation, and is supplied to the controller 9 as correction data. Is entered.

In the control device 9, the drive control current to the solenoid device 8 of the proportional solenoid control valve 4 is corrected according to the magnitude of these fluctuation data by a preset amount, for example, in proportion to the change in the pump volumetric efficiency. It is like this. Further, in the control device 9, the size of each input variation data is compared and monitored with a reference level set for each, and an alarm is issued individually or in combination for those exceeding the upper limit level. Thus, it is possible to know the abnormality of the device in the system before the failure.

〔The invention's effect〕

As described above, according to the present invention, in addition to closed loop feedback control of pressure and flow rate by a single proportional solenoid control valve, correction by fluctuation data in the system is also incorporated in the loop for extremely precise control. Moreover, by monitoring the fluctuation data, it becomes possible to detect the failure of the device in the system in advance.

[Brief description of drawings]

The drawings are circuit diagrams showing the configuration of the entire system of a variable displacement pump according to an embodiment of the present invention. 2: Pump element, 3: Discharge amount variable element, 4: Proportional solenoid control valve,
5: Safety valve, 6: Pressure sensor (pressure detection means), 7: Displacement detector (flow rate detection means), 8: Solenoid device, 9: Control device,
10: Pressure setting signal input terminal, 11: Flow rate setting signal input terminal,
15: Revolution detector, 16: Oil temperature detector, 17, 18: Speed detector.

Claims (1)

[Claims] 1. The displacement of the variable element (3) is controlled against the spring force by controlling the hydraulic pressure in the pressurizing chamber of the variable discharge amount element (3) by means of a proportional electromagnetic control valve (4), and the maximum In the variable displacement pump in which the discharge amount is variable within the range of the discharge amount to the full cutoff, the flow rate detecting means (7) for generating an electric signal corresponding to the discharge amount of the pump (2) and the discharge pressure of the pump are provided. The drive control current supplied to the proportional electromagnetic control valve (4) is controlled according to the deviation between the pressure detection means (6) that generates an electrical signal and the output signal of the flow rate setting signal (11) and the flow rate detection means (7). At the same time, when the pump discharge pressure detected by the pressure detecting means (6) reaches a preset set value, the drive control is performed based on the deviation between the pressure setting signal (10) and the output signal of the pressure detecting means (6). Control means for controlling current (9 ) And data detecting means (6, 15-18) for detecting fluctuation data of pump discharge pressure, actuator operating speed, pump circuit speed, or pump operating oil temperature during pump operation, and control means (9) Is a variable displacement pump having a correction function of correcting the drive control current according to the magnitude of fluctuation data by the detection output of the data detection means (6, 15-18).