JPH03985A - Hydraulic power supply device - Google Patents

Abstract

PURPOSE:To prevent a sudden increase or decrease in a total delivery amount during a transient time by devising a flowrate setting method for a variable delivery pump assigned to the proportional control of the total delivery amount in the system wherein the total flowrate of a plurality of variable delivery pumps is controlled and supplied to an actuator. CONSTITUTION:The first variable delivery pump 1 having the operation piston 4 of a variable delivery element 2 supplied with pilot pressure to be controlled with a proportional electromagnetic three-way valve 5, is provided together with the second variable delivery pump 12 having the operation piston 15 of a variable delivery element 13 supplied with pilot pressure to be controlled with a pressure compensator valve 17. Fluids delivered from the aforesaid pumps 1 and 12 are converged and supplied to an actuator 20. In this case, a detecting means 21 for detecting the delivery amount of the second pump 12 is provided, and when a flowrate set signal exceeds a totalling start set value, the subtraction 11 of a value measured with the detecting means 21 from the flowrate set signal is made, and the subtracted value is inputted to a control amp device 10 as a flowrate set value, thereby controlling the delivery amount of the first pump 1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a plurality of variable displacement pumps for controlling the discharge flow rate proportionally to a set human input signal at a large flow rate within a predetermined discharge pressure range. The present invention relates to a hydraulic pressure supply system that electrically controls the total flow rate of the flow rate, and particularly relates to improving responsiveness during transitions in flow rate totalization.

[Prior Art] For example, in hydraulically operated processing machines, there are cases in which a large flow rate of pressurized oil is required to be supplied in the control process, and cases in which pressure is required but almost no flow rate is required. In such a case, for example, Japanese Patent Application Laid-Open No. 63-11590
As shown in Publication No. 2, one proportional electromagnetic pressure flow rate controlled variable displacement pump and another pressure convencator controlled variable displacement pump with unloading are installed in parallel, and the discharge rate variable mechanism of both pumps is established. is electrically controlled by an electromagnetic control valve, and the total flow rate is controlled in proportion to the set human input signal.

FIG. 2 is a circuit diagram of a hydraulic pressure supply device similar to that disclosed in Japanese Unexamined Patent Publication No. 115902/1983. In FIG. 2, 1 is a first variable displacement pump (hereinafter referred to as the first pump), 2 is a variable discharge amount element of the first pump 1,
The discharge amount variable element 2 is displaced by the spring force of the spring 3 and the operating force of the operating piston 4 to change the discharge amount of the first pump. 5 is a proportional electromagnetic three-way control valve, and 6 is a safety valve.

The proportional electromagnetic three-way control valve 5 increases the pilot pressure in the pressure chamber of the operation piston 4 to apply operating force to the discharge amount variable element 2 by introducing a part of the discharge pressure oil through the pilot line or to the tank. Proportional control is performed according to the electrical signal to derive and lower the voltage. For this proportional control, the control amplifier device 10 that controls the excitation current of the proportional 6N solenoid of the proportional N 6B three-way control valve 5 has a setting input terminal 9.
the pressure setting signal from a, the flow rate setting signal from the setting input terminal 9b via the subtractor 11, the discharge pressure feedback signal detected by the pressure sensor 8, and the displacement detector 7 detected as the displacement of the discharge amount variable element 2. receives a discharge amount feedback signal from the pump and performs electro-hydraulic closed loop feedback control. By controlling the pilot pressure in this manner, the position of the discharge amount variable element 2 is controlled via the operation piston 4 against the spring force of the spring 3, and when the discharge pressure is less than the set pressure, the discharge amount is made equal to the set flow rate. When the discharge pressure reaches the set value, the discharge amount variable element 2 is moved to the cut-off position where the discharge amount is the minimum required.

12 is a second variable displacement pump (hereinafter referred to as the second pump), and the discharge line of the second pump 12 is connected to the check valve 18.
It joins the discharge line of the first pump 1 via. 1
3 is a discharge amount variable element of the second pump 12, and this discharge amount variable element 13 is also controlled by the spring force of the spring 14 and the operating piston 1.
It is displaced by the operating force of step 5 to change the discharge amount. This discharge amount variable element 13 is equipped with pressure convencator control with unloading using a three-way electromagnetic switching valve 16 and a pressure convencator valve 17. The operation of the three-way electromagnetic switching valve 16 is controlled by the output of a comparator 19, and this comparator 19 controls the magnitude of the flow rate setting signal at the terminal 9b.
Compared with the summation start set value set in a, when the flow rate setting signal is below the summation start set value, the output is kept at;, and when the flow rate setting signal exceeds the summation start set value, the three-way electromagnetic switching valve 16 is turned on. produces an output for switching from the position. This output of the comparator is also given to the minus input terminal of the subtracter 11, and at this time, the flow rate setting signal input to the terminal 9b is changed to the constant discharge amount of the second pump 12 by the subtracter 11 according to the signal from the comparator 19. The corresponding amount is subtracted and applied to the input terminal 9C of the control amplifier device 10.

Therefore, when the flow rate setting signal manually input to the setting input terminal 9b is less than the summation start setting value predetermined by the setting device 19a, the three-way electromagnetic switching valve 16 does not output the output from the comparator 19, so the three-way electromagnetic switching valve 16 is in the position shown in the figure. The pressure oil discharged from the second pump 12 is directly introduced into the operating piston 15 to control the second pump 1.
2 is in an unloaded state. In this state, only the pressure oil discharged from the first pump 1 is supplied to the actuator 20 at the set flow rate.

When the flow rate setting signal exceeds the summation start setting value,
The output from the comparator 19 causes the three-way electromagnetic switching valve 16 to switch from the illustrated position, thereby leading the pressure oil in the operating piston 15 to the tank via the pressure convencator valve 17, so that the second pump 12 The discharge is performed at the set maximum discharge rate, and this discharge flow rate is added to the discharge flow rate of the first pump 1 and supplied to the actuator 20. In this case, at the same time as the output of the comparator 19 rises, the output level of the subtracter 11 suddenly decreases by a predetermined value.
As a result, the magnitude of the flow rate setting input for the first pump 1 that has been applied to the control amplifier device 10 is lowered by an amount equivalent to the discharge amount of the second pump 12.

The hydraulic pressure supply device configured as described above has the ideal characteristics of the flow rate setting signal and the total discharge flow rate shown in FIG. !
It is aimed at control.

That is, when the flow rate setting signal manually inputted to the input terminal 9b is smaller than the preset summation start setting value S1, the comparator 19 determines this, and the output signal of the comparator 19 is set to zero, and the three-way electromagnetic switching valve 16 is placed in an excited state and the second pump 12 is placed in an unloaded state. On the other hand, the output from the comparator 19 is also sent to a subtracter 11 provided between the input terminal 9b and the control amplifier device 10. The subtracter 11 has an input terminal 9
The output from the comparator 19 given by a predetermined manual gain, which is the flow rate setting signal inputted to b, is subtracted, and the output is manually input to the control amplifier device 10. The output signal of the comparator 19 sent to the subtracter 11 is flat until the flow rate setting signal reaches the summation start setting value S, so in that case, the flow rate setting signal is sent to the input terminal 9c of the control amplifier device 10. The flow rate is controlled by the first pump 1 only by hand.

When the flow rate setting signal at the input terminal 9b increases and becomes larger than the summation start set value S+, the comparator 19 determines this and excites the three-way electromagnetic switching valve 16 to switch, and the second pump 12 changes to the summation start set value. Correspondingly, a constant flow rate Q2 is discharged. This setting of Q2 is performed by setting the maximum discharge amount adjusting screw of the second pump 12. Simultaneously with the excitation of the three-way switching valve 16, a signal representing the summation start set value S1 is sent to the subtractor 11 from the comparator 19. Therefore, a difference signal between the flow rate setting signal and the summation start setting value corresponding to the discharge flow rate Q2 of the second pump 12 is manually input to the input terminal 9C of the control amplifier device 10 as a flow rate setting, and this difference signal is used as the flow rate setting value of the first pump 1. The discharge amount is controlled.

In this way, at the same time when the flow rate setting signal exceeds the summation start setting value S1 and the second pump 12 operates at the discharge amount Q2, the flow rate setting of the first pump 1 is set to ; and then increased again. , in the opposite case, the flow rate setting signal falls to the summation start setting value S, and the second pump 12 unloads, and at the same time, the flow rate setting of the first pump 1 is changed from ; to the discharge amount Q2, and then the control is performed to decrease it. I will do it.

[Problem to be Solved by the Invention] In the summation control of the conventional hydraulic pressure supply device configured as described above, when the flow rate setting signal reaches the summation start setting value, statically the first pump 1 Discharge flow rate and second pump 1
The two discharge flow rates can be summed up satisfactorily.

However, dynamically, changes in the discharge amount of both pumps occur over a finite period of time determined by the responsiveness of the pump's variable discharge amount mechanism, and the flow rate setting signal is gradually increased until the flow rate setting signal reaches the summation start setting. In order to obtain the total discharge flow rate according to the change in the flow rate setting signal during a transient period when the value S1 is reached, the discharge flow rate of the second pump 12 increases toward Q2, and the discharge flow rate of the first pump 1 decreases. It is necessary to make the time for the discharge amount of the first pump 1 to decrease to zero and the time for the discharge amount of the second pump 12 to increase and reach the maximum flow rate Q2 to be the same.

However, the responsiveness of an actual variable displacement pump differs when the discharge amount increases and decreases, and usually also changes depending on the load pressure. For this reason, there is a difference between the discharge amount reduction time of the first pump 1 and the discharge amount increase time of the second pump 12 during the transient period, and the time until the discharge amount of the first pump 1 becomes zero is different from the second pump 12. is longer than the time required to reach the maximum discharge amount, the total discharge amount becomes larger than the flow rate set by the flow rate setting signal, as shown by the solid line A in the flow rate characteristic diagram of FIG. Conversely, if the time it takes for the discharge amount of the first pump 1 to drop to a drop is shorter than the time it takes for the second pump 12 to reach the maximum discharge amount, the total discharge amount will be reduced as shown by the broken line B in FIG. becomes smaller than the flow rate set by the flow rate setting signal, and when the flow rate setting signal reaches the summation start set value S, there is a disadvantage that discontinuity occurs in the total discharge amount.

The present invention has been made to solve these shortcomings, and it is an object of the present invention to smoothly change the total discharge amount according to a flow rate setting signal without causing discontinuity when adding up the discharge amount of a plurality of pumps. The purpose of this invention is to provide a hydraulic supply device that can perform the following functions.

[Means for Solving the Problems] In order to achieve the above-mentioned problems, in the hydraulic supply device according to the present invention, the electro-hydraulic system is controlled by the pressure setting signal, the flow rate setting signal, and the measurement signals corresponding to the discharge pressure and the discharge flow rate, respectively. A proportional electromagnetic pressure flow rate control type variable displacement pump which controls the discharge pressure and pump displacement with a proportional electromagnetic control valve through closed-loop feedback control;
a pressure convencator-controlled variable displacement pump with an unloading unit that is brought into an unload state by a valve and discharges at a preset constant flow rate when the flow rate setting signal exceeds the summation start set value; In a hydraulic supply device that combines the discharge pressure oil of both pumps and supplies it to the load when the summation start setting value is exceeded, an electric signal corresponding to the discharge amount of the pressure convencator-controlled variable displacement pump with unloading is output. and a subtraction means that subtracts the measured value by the detection means from the flow rate setting signal when the flow rate setting signal exceeds the summation start setting value, and further comprising: The displacement pump is equipped with a discharge rate variable mechanism whose responsiveness is relatively higher than that of the pressure convencator-controlled variable displacement pump with unloading.

[Function] In this invention, when the flow rate setting signal reaches the summation start setting value, the manual effort for setting the flow rate of the proportional electromagnetic pressure flow rate control type variable displacement pump, which is responsible for the proportional control of the total discharge flow rate, is subtracted. Instead of directly using the comparator output, an electrical signal corresponding to the actual discharge amount of the pressure convencator-controlled variable displacement pump with unloading that discharges a fixed total additional flow rate is obtained from the detection means, and the actual The subtraction of the flow rate setting signal is controlled in such a manner that the second pump discharges the set maximum discharge amount in time.

In this case, in order to follow the operation of the variable discharge rate mechanism of a pressure convencator-controlled variable displacement pump with unloading, the overall responsiveness of the variable discharge rate mechanism of the proportional electromagnetic pressure flow rate controlled variable displacement pump must be increased. You need to choose.

In cases where the responsiveness of both pumps is the same, an appropriate throttling element may be added to the pilot line of the variable discharge mechanism of a pressure convencator controlled variable displacement pump with unloading in order to differentiate the responsiveness. Needless to say.

A preferred embodiment of the present invention will be described below with reference to the drawings.

[Embodiment] FIG. 1 is a circuit diagram showing an embodiment of the present invention.
In the figure, numerals 1 to 20 are exactly the same as the conventional example shown in FIG. However, the discharge rate variable element 2 of the first pump 1 has a relatively higher responsiveness than the discharge rate variable element 13 of the second pump 12, and the output of the comparator 19 is higher than that of the three-way electromagnetic switching valve 16. given only to 21 is the second
This is a displacement detector that measures the displacement of the discharge amount variable element 13 of the pump 12 to detect a measured value corresponding to the discharge amount of the second pump 12, and the output of the displacement detector 21 is the same as that of the conventional comparator 19. The flow rate setting of the first pump 1 is inputted to the input terminal on the positive side of the subtractor 11 in place of the output of signal, actually the second pump 12
is controlled by subtraction in a time-aligned manner to discharge the set maximum discharge amount. 22 is provided between the three-way electromagnetic switching valve 16 and the operation piston 15 of the second pump 12;
This is a diaphragm that adjusts the responsiveness of the discharge amount of 2, and this diaphragm 2
By appropriately selecting the opening degree of the second pump 12, the response of the second pump 12 is made slower than that of the first pump 1.

The first pump 1 receives a set pressure manually input from an input terminal 9a and a flow rate setting signal manually input from an input terminal 9b and sent through a subtracter 11 at a control amplifier device 10. The control amplifier device 10 performs electro-hydraulic closed loop feedback control of the flow rate based on the flow rate setting signal and the measured electrical quantity of the discharge amount measured by the displacement detector 7 when the electrical quantity measured for the discharge pressure by the pressure sensor 8 is below the set pressure. This is done via the proportional electromagnetic three-way control valve 5, and the pilot pressure in the pressure chamber of the operating piston 4 is controlled to displace the position of the discharge amount variable element 2, thereby controlling the discharge amount of the first pump 1. Further, when the amount of electricity measured for the discharge pressure by the pressure sensor 8 reaches the set pressure, the proportional electromagnetic three-way control valve 5 guides the discharge pressure of the first pump 1 into the pressure chamber of the operating piston 4, and the first pump 1 is in a full cut-off state. Make it. During closed loop feedback control of the discharge pressure and discharge amount of the first pump 1, the flow rate setting signal inputted to the input terminal 9b is sent to the comparator 19, and the summation start set in advance by the setting device 19a is performed. It is compared with the set value. When the flow rate setting signal is below this summation start setting value, an off signal is sent from the comparator 19 to the three-way electromagnetic switching valve 16 of the second pump 12, and the three-way electromagnetic switching valve 16 is demagnetized and the second pump 12 is unloaded. leave it in a state. When the flow rate setting signal exceeds the summation start setting value, the comparator 19 sends an ON signal to the three-way electromagnetic switching valve 16, energizing the three-way electromagnetic switching valve 16, and pressurizing the pressure chamber of the operating piston 15 of the second pump 12. It communicates with the tank via the convencator valve 17, thereby causing the discharge rate variable element
3 is displaced to the maximum discharge amount position by a spring 14 to make the discharge amount a preset maximum value. This change in the discharge amount of the second pump 12 is detected by the displacement detector 21 as a displacement of the discharge amount variable element 13, and is sent to the minus input terminal of the subtracter 11.

A case where the total discharge amount of the first pump and the second pump 12 is controlled with the ideal characteristic as shown in the discharge amount characteristic of FIG. 3 using the above configuration will be described.

When the flow rate setting signal manually input to the setting input terminal 9b is smaller than the preset summation start setting value Sl, the comparator 19 that has determined this outputs an off signal, and the three-way electromagnetic switching valve 16 is in a demagnetized state. It has become. Therefore, the second pump 12 is in an unloaded state, and its discharge amount variable element 13 is at a position corresponding to the discharge amount;
The discharge amount measurement signal of 1 is almost a drop. Therefore, the flow rate setting signal manually input to the flow rate setting input terminal 9b is sent as is from the subtracter 11 to the input terminal 9C of the control amplifier device 10, and the discharge pressure of the first pump 1 is determined by the manually input set pressure and flow rate setting signal. The discharge amount is controlled as described above.

When the flow rate setting signal inputted to the flow rate setting input terminal 9b gradually increases and reaches the summation start set value S, the comparator 1
An on signal is output from 9, and the three-way electromagnetic switching valve 16 is energized. When the three-way electromagnetic switching valve 16 becomes energized, the pressure oil in the pressure chamber of the operating piston 15 is led out from the three-way electromagnetic switching valve 16 to the tank via the pressure convencator valve 17, and the discharge amount of the second pump 12 is throttled 22. The flow rate corresponding to the summation start setting value S1 is set to the maximum discharge amount Q2 in the predetermined response time adjusted in . At this time, the second pump 1
2 is detected by the displacement detector 21, and the subtractor 1
Send to 1. The measurement signal from the displacement detector 2 is a signal that changes over the response time of the change in the discharge amount of the second pump 12. The subtractor 11 subtracts the flow rate setting signal manually input to the input terminal 9b and the measured value of the discharge amount of the second pump 12 sent from the displacement detector 21 by an appropriate gain, and controls the difference signal. It is sent to the input terminal 9C of the amplifier device 10. Therefore, the first pump 1 operates to reduce the discharge amount based on the difference signal sent from the subtractor 11. In this way, when the discharge amount of the second pump 12 reaches the maximum flow rate Q2, the discharge amount of the first pump 1 becomes exactly ;, and then as the flow rate setting signal increases, the first pump 1 again operates proportionally. As a result, the total discharge amount increases.

When reducing the total ejection amount, the same operation is performed in reverse order as described above.

In the above embodiment, the case where a variable displacement pump on a stand is used has been described, but it goes without saying that the present invention can also be applied to total control using pumps on a stand or higher.

Therefore, since the second pump actually discharges the set maximum discharge amount, it is controlled in a time-aligned manner, so even during a transition period when the summation of the discharge amounts of both pumps starts or ends, the total discharge amount remains unchanged. The total discharge amount can be smoothly changed according to the flow rate setting signal without causing discontinuity by preventing sudden increases or decreases in the flow rate, and the flow rate according to the flow rate setting signal can be continuously and stably supplied to the load. It is something that can be done.

[Effects of the Invention] As explained above, the present invention provides a proportional electromagnetic pressure flow rate controlled variable displacement pump that proportionally controls the discharge amount, and a pressure convencator controlled variable displacement pump with unloading that discharges a constant total additional flow rate. subtracting the flow rate setting input of the proportional electromagnetic pressure flow rate control type variable displacement pump, which is essentially responsible for proportional control of the total discharge flow rate, when the flow rate setting signal reaches the summation start setting value using the pump, An electrical signal corresponding to the actual discharge amount of the pressure compensator-controlled variable displacement pump with unloading is obtained from the detection means.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a circuit diagram showing a conventional example, Fig. 3 is a characteristic diagram showing an ideal change in total discharge amount with respect to a flow rate setting signal, and Fig. 4 1 is a schematic characteristic diagram showing actual operating characteristics of a conventional example. (Explanation of symbols of main parts) 1... First pump (proportional electromagnetic pressure flow rate controlled variable displacement pump) 5... Proportional type 6n flow control valve 6... Safety valve 7... Displacement detector 8... Pressure sensor 10... IIJ control amplifier device 11... Subtractor (subtraction means) 12... Second pump (pressure compensator controlled variable displacement pump with unloading) 6... Electromagnetic Switching valve 7...Pressure convencator valve 8...Check valve 9...Comparator 1...Displacement detector (detection means) 2...Aperture Figure 3 Figure 4 Agent Patent attorney Sa Masaru Fuji Flow rate setting signal□

Claims (1)

[Claims] Proportional control in which the electro-hydraulic system is controlled in closed loop feedback using a pressure setting signal, a flow rate setting signal, and measurement signals corresponding to the discharge pressure and discharge flow rate, respectively, and the discharge pressure and pump displacement are controlled by a proportional electromagnetic control valve. The electromagnetic pressure flow rate controlled variable displacement pump is in an unload state by a solenoid valve when the flow rate setting signal is less than a predetermined summation start set value, and when the flow rate setting signal exceeds the summation start set value, It is equipped with a pressure convencator-controlled variable displacement pump with unloading that discharges at a set constant flow rate, and when the set flow rate exceeds the summation start set value, the discharge pressure oil of both pumps is combined and supplied to the load. A hydraulic supply device comprising: a detection means for outputting an electric signal corresponding to a discharge flow rate of the pressure convencator-controlled variable displacement pump with unload; and a subtraction means for subtracting the measured value by the detection means from the setting signal, the discharge amount of the proportional electromagnetic pressure flow rate controlled variable displacement pump is lower than the discharge amount variable mechanism of the pressure convencator controlled variable displacement pump with unloading. A hydraulic pressure supply device characterized in that a variable amount mechanism has relatively high responsiveness.