JPS62220701A - Variable delivery pump - Google Patents

Abstract

PURPOSE:To achieve a precise control and find a malfunction of any apparatus in advance by taking a correction in compliance with variation data in the system into a loop, in addition to the closed loop feedback control of pressure and flow. CONSTITUTION:A controller 9 is provided with a pressure setting signal input terminal 10 and a flow setting signal input terminal 11 while furthermore outputs from a rotation detector 15 for a motor 1, a temperature detector 16 and speed detectors 17, 18 are input therein. The controller 9 provides correction of preset quantity over a drive control current toward a solenoid device 8 in a proportional solenoid control valve 4 in compliance with the magnitude of said variation data. The magnitude of each variation data is monitored in comparison with a referential level and an alarm is produced when an upper limit level is exceeded. Consequently, a precise control is achieved and a malfunction of any apparatus can be found in advance.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a variable displacement pump.

[Conventional technology]

A conventional method using a proportional electromagnetic control valve to control the discharge flow rate and discharge pressure in a variable displacement pump is known7. In the general conventional method, a proportional electromagnetic relief valve is used to control the discharge pressure. The pressure is set according to the input current.The pressure is controlled by the 411 pressure feed puncture, and for the discharge flow -ui, another proportional solenoid control valve is used to discharge the pump! $I: Controlled mutation of the riT variable element.

In such conventional variable displacement pumps, proportional electromagnetic control valves are prepared and used separately for controlling pressure and flow rate, so not only the control valves but also the current amplifiers for driving them are used separately. Therefore, it was inevitable that the equipment would become larger and its power consumption would increase. In addition, with conventional variable displacement pumps (well, if the rotation speed changes due to a change in the slip amount of the pump drive motor due to load fluctuations, this will appear as a change in the pump discharge amount, and the volumetric efficiency of the pump will change due to an increase in load pressure etc.) Fluctuations in discharge amount cause changes in the speed of actuators such as hydraulic motors and cylinders.Furthermore, changes in viscosity due to temperature changes in the hydraulic oil also appear as changes in discharge amount. This is particularly problematic when various factors exist and precise control is required.

[Problem that the invention seeks to solve]

The problem to be solved by the present invention is to control both pressure and flow rate using a closed loop feedback control system including a hydraulic system using a single proportional electromagnetic control valve. By applying correction, it is possible to exhibit characteristics suitable for precision control, and
It is an object of the present invention to provide a variable displacement pump capable of monitoring the level of fluctuation factors and giving advance warning of equipment abnormalities.

Means for Solving Problem c] 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 rate element using a proportional electromagnetic control valve. , a variable displacement pump whose discharge volume is variable within the range from the maximum discharge volume to the cut-off range.
A flow rate detection means that generates an electric signal corresponding to the discharge amount of the pump, a pressure detection means that generates an electric signal corresponding to the pump discharge pressure, and a flow rate setting signal and output No. 3 of the flow rate detection means. The drive control current supplied to the proportional electromagnetic control valve is controlled according to the deviation, and when the detected pump discharge pressure reaches a set value, the drive control current is controlled based on the deviation between the pressure setting signal and the output signal of the pressure detection means. A control means for controlling the drive control current, a data detection means for detecting fluctuation data during pump operation such as pump discharge pressure, actuator operating speed, pump rotation speed, pump hydraulic oil temperature, and a detection output of the data detection means. and a correction means for correcting the drive control current according to the magnitude of the fluctuation data.

In one preferred embodiment of the present invention, the data detection means includes abnormality detection means that monitors the magnitude of its own detection output and outputs an alarm signal when the magnitude of the detection output exceeds a predetermined upper limit. □ I'm working on it.

[Effect]

In the present invention, for controlling the drive control current of the proportional electromagnetic control valve that hydraulically controls the displacement of the pump discharge variable element,
For example, a flow rate feedback signal is obtained from the displacement amount of a pump's discharge variable element, the deviation from the set value is taken, and the discharge flow rate is feedback-controlled in an electro-hydraulic closed loop.
The discharge pressure detected by a pressure sensor, etc. is compared with the pressure setting value to perform cut-off control in an electro-hydraulic closed loop, and also to collect data on fluctuations during pump operation, such as pump discharge pressure, actuator operating speed, pump rotation speed, pump hydraulic oil temperature, etc. is detected by the data detection means, and the correction means corrects the drive control current controlled by the closed loop control system based on the detection output of the data detection means in accordance with the magnitude of the fluctuation data, thereby adjusting almost the entire hydraulic system. In addition to realizing closed-loop precision control that includes in the loop, it is also possible to provide a predictive diagnosis function for failures such as equipment abnormalities using detected fluctuation data.

〔Example〕

The drawing is a circuit diagram showing the overall system configuration of a variable displacement pump according to an embodiment of the present invention, in which a boss element 2 connected to the rotating shaft of an electric motor 1 is moved by displacement of its discharge amount variable element 3. Change the discharge flow rate. The hydraulic system for controlling the discharge amount includes a proportional electromagnetic control valve 4 that controls the hydraulic pressure in its pressurizing chamber in order to displace the variable element 3 against the spring force, and a proportional electromagnetic control valve 4 that controls the hydraulic pressure in the pressurizing chamber when the discharge pressure reaches a set upper limit. and a safety valve 5 which displaces the variable element 3 regardless of the proportional electromagnetic control valve 4 to bring the pump into a full cut-off 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 displacement amount of the variable element 3 as a detection amount corresponding to the discharge flow rate of the pump.
and a control device 9 that forms a feedback loop with these sensors and detectors and supplies a drive control current to the solenoid device 8 of the control valve 4 in accordance with the set values of pressure and flow rate.

The control device 9 includes 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 detected fluctuation data value, which will be described next.

The actuating control valve arrangement 12, such as a directional valve, connected to the pump delivery line is symbolically shown in block form in this case. The figure shows a cylinder 13 and a hydraulic motor 14 as actuators whose speed and torque are controlled by pump discharge oil via this control valve device 12.

15 is a rotation speed detector that detects the rotation speed of the electric motor 1;
16 is a temperature detector that detects the oil temperature of the pump, 17 is a speed detector that detects the speed of the cylinder 13, and 18 is a speed detector that detects the speed of the hydraulic motor 14. These detectors detect various fluctuations in the system. Data is detected dynamically during operation and is input as correction data to the control device M9.

The control device 9 applies a correction to the drive control current to the solenoid device 8 of the proportional electromagnetic control valve 4 in an amount commensurate with a preset change in pump volumetric efficiency, for example, according to the magnitude of these fluctuation data. It looks like this. Furthermore, within the control device 9, the magnitude of each input fluctuation data is compared and monitored with the reference level set for each, and if the data exceeds the upper limit level, an alarm is issued individually or in combination. This makes it possible to detect abnormalities in equipment within the system before they fail.

〔Effect of the invention〕

As described above, according to the present invention, in addition to closed-loop/private pack control of pressure and flow rate using a single proportional solenoid control valve, correction based on fluctuation data within the system is incorporated into the loop, making it extremely This allows for precise control, and furthermore, by monitoring fluctuating data, it is also possible to discover equipment failures in the system in advance.

[Brief explanation of drawings]

The drawing is a circuit diagram showing the overall system configuration of a variable displacement pump according to an embodiment of the present invention. 2: Pump element, 3: Discharge rate variable element, 4: Proportional electromagnetic 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: Rotation speed detector, 16: Oil temperature detector, 17° 18: Speed detector.

Claims (2)

[Claims] 1. 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 rate element using a proportional solenoid control valve, and the discharge rate can be varied within the range from the maximum discharge rate to the cutoff. In the variable displacement pump, the flow rate detection means generates an electric signal corresponding to the discharge amount of the pump;
pressure detection means for generating an electric signal corresponding to the pump discharge pressure; and a pressure detection means for controlling and detecting a drive control current supplied to the proportional electromagnetic control valve according to a deviation between a flow rate setting signal and an output signal of the flow rate detection means. control means for controlling the drive control current based on the deviation between the pressure setting signal and the output signal of the pressure detection means when the pump discharge pressure reaches a set value; and a control means for controlling the drive control current based on the deviation between the pressure setting signal and the output signal of the pressure detection means; , a data detection means for detecting fluctuation data during pump operation such as pump hydraulic oil temperature, and a correction means for correcting the drive control current according to the magnitude of the variable data based on the detected output of the data detection means. A variable displacement pump characterized by: 2. The variable capacity type according to claim 1, wherein the data detection means includes an abnormality detection means that monitors the magnitude of its own detection output and outputs an alarm signal when the magnitude exceeds a predetermined upper limit. pump.