CN112377400A - Variable pump variable control device and control method - Google Patents

Abstract

The invention relates to a variable control device and a control method for a variable pump. The variable pump variable control device of the invention comprises: the variable pump control valve comprises a main valve body, an electromagnet, an auxiliary valve body, a valve core, an iron core, a main spring, an auxiliary spring and a piston; the main valve body is provided with a valve core mounting cavity along the axial direction, and an oil inlet, a control oil port and an oil return port which are respectively communicated with the valve core mounting cavity along the radial direction; the oil inlet is communicated with an oil outlet of the pump body; the oil return port is communicated with the oil tank; the control oil port is communicated with the rodless cavity of the variable oil cylinder. The variable control device and the control method of the variable pump not only realize the switching between the working state and the standby state of the variable pump, but also achieve the purpose of controlling the variable speed of the variable pump in the switching process, are suitable for mechanical equipment with frequent standby, and solve the problem that the service life of the variable pump is influenced by frequent and quick variable.

Description

Variable pump variable control device and control method

Technical Field

The invention relates to the field of variable pump variable control, in particular to a variable pump variable control device and a variable pump variable control method.

Background

The variable displacement pump can adapt to the complex working condition requirement of the machine during operation through displacement adjustment, and therefore, the variable displacement pump is widely applied to a hydraulic system. Referring to fig. 1, fig. 1 is a schematic diagram of a hydraulic system of a variable displacement pump in the prior art. The conventional variable displacement pump control device includes a variable displacement pump 1e, an oil tank 2e, a variable cylinder 3e, a pressure valve 4e, a orifice 5e, and a solenoid valve 6 e. When the mechanical equipment is in a standby state, the variable pump 1e can keep a low-pressure and small-displacement standby state (low pressure refers to lower pressure which can ensure that a lubricating oil film is generated in the variable pump, small displacement refers to minimum displacement of the variable pump for maintaining the low pressure, and the actual size of the value depends on the rotating speed of the variable pump and the leakage amount of each related hydraulic element under the low pressure), so that the energy-saving effect is achieved, and the service life of the pump is prolonged. For convenience of explanation, a ratio of a spring force of the pressure valve 4e to a spool sectional area of the pressure valve 4e, namely, a pressure generated by a spring of the pressure valve 4e, is referred to as Pa. The specific working process is as follows:

when the variable pump 1e is required to enter a standby state from a working state, the electromagnetic valve 6e is electrified, the electromagnetic valve 6e works at the right station, the right chamber of the pressure valve 4e is communicated with the oil tank 2e through the right station of the electromagnetic valve 6e, and the liquid pressure of the right chamber of the pressure valve 4e is about zero. At this time, the right chamber of the pressure valve 4e only has the pressure Pa set by the pressure regulating spring, and the liquid pressure at the outlet of the variable pump 1e is greater than Pa (mechanical equipment powered by the variable pump, generally, the mechanical equipment enters a standby state before the variable pump, in the time period between the two standby states, the mechanical equipment does not consume energy, the variable pump still supplies energy at the maximum displacement, the liquid pressure at the outlet of the variable pump depends on an energy accumulator or a safety overflow valve in the mechanical equipment and is much greater than Pa), the left chamber of the pressure valve 4e is communicated with the outlet of the variable pump 1e, and the liquid pressures are equal. Therefore, the pressure of the left cavity of the pressure valve 4e is greater than the pressure of the right cavity, the valve core moves to the right, and the left station works. At the moment, a rodless cavity of the variable cylinder 3e is communicated with an outlet of the variable pump 1e through a left station of the pressure valve 4e, a rod cavity of the variable cylinder 3e is communicated with an outlet of the variable pump 1e, liquid pressure at two sides is equal, but the area of the rodless cavity of the variable cylinder 3e is larger than that of the rod cavity, the reset spring force of the rod cavity of the variable cylinder 3e is relatively small and can be ignored, so that the pressure of the rodless cavity of the variable cylinder 3e is larger than that of the rod cavity, a piston in the variable cylinder 3e moves leftwards to push the variable pump 1e to swing, the displacement of the variable pump 1e is reduced, and the liquid pressure at the outlet of the variable pump 1e is reduced subsequently. When the outlet liquid pressure of the variable pump 1e is reduced to Pa, the left cavity liquid pressure of the pressure valve 4e is also reduced to Pa, at the moment, the left cavity and the right cavity of the pressure valve 4e have equal pressure, the valve core of the pressure valve 4e returns to a middle position state, the liquid of the rodless cavity of the variable cylinder 3e does not increase or decrease, the piston of the variable cylinder 3e stops moving, and the variable pump 1e does not change variables any more. The variable displacement pump 1e then starts to maintain the pressure of Pa at a small displacement, and remains in a standby state. When the variable pump 1e is required to enter a working state, the electromagnetic valve 6e is powered off, the electromagnetic valve 6e works at a left station, the right cavity of the pressure valve 4e is not communicated with the oil tank 2e any more, but is communicated with the outlet of the variable pump 1e through the damping hole 5e, and the liquid pressure intensity of the right cavity of the pressure valve 4e is equal to the liquid pressure intensity of the left cavity. However, the pressure Pa generated by the spring is also arranged in the right cavity of the pressure valve 4e, so the total pressure of the right cavity of the pressure valve 4e is greater than that of the left cavity, the valve core of the pressure valve 4e moves leftwards, the rodless cavity of the variable cylinder 3e is communicated with the oil tank 2e through the right station of the pressure valve 4e, the liquid pressure of the rodless cavity of the variable cylinder 3e becomes zero, the piston of the variable cylinder 3e moves rightwards under the action of the hydraulic pressure of the rod cavity of the piston and the action of the return spring, the displacement of the variable pump 1e is increased, and the energy supply to mechanical equipment. When the variable pump 1e needs to enter the standby state again, the electromagnetic valve 6e is powered, and the standby state and the working state of the variable pump 1e can be switched repeatedly.

This control method has a problem: the switching process of power on and power off of the electromagnetic valve is completed instantly, so that the switching standby state and the working state of the variable pump are also completed instantly, the variable speed of the variable pump in the control process is extremely high, the service life of the variable pump is influenced by the excessively high variable speed, and the standby control method is not suitable for mechanical equipment which is frequently standby.

Disclosure of Invention

Accordingly, an object of the present invention is to provide a variable control device for a variable pump and a control method thereof, which can control a variable speed, a variable direction, and a displacement of the variable pump, and can also control the variable pump to maintain a low-pressure and small-displacement standby state, and which are suitable for a mechanical device that is frequently in standby, and solve a problem that the service life of the variable pump is affected by frequent standby.

The invention is realized by the following technical scheme: a variable pump variable control device comprises an oil tank, a variable pump and a variable pump control valve, wherein the variable pump comprises a pump body and a variable oil cylinder; the variable pump control valve comprises a main valve body, an electromagnet, an auxiliary valve body, a valve core, an iron core, a main spring, an auxiliary spring and a piston; the main valve body is provided with a valve core mounting cavity along the axial direction, and an oil inlet, a control oil port and an oil return port which are respectively communicated with the valve core mounting cavity along the radial direction; the end face of one side of the main valve body is hermetically connected with the electromagnet, a first cavity communicated with the valve core mounting cavity is formed in the contact surface, and the first cavity is communicated with the oil inlet through a liquid path; the end face of the other side of the main valve body is connected with the auxiliary valve body in a sealing way; the valve core penetrates through the valve core mounting cavity and can move in the valve core mounting cavity, so that the communication between the oil inlet and the control oil port or the communication between the control oil port and the oil return port is realized; when the valve core is in the middle position, the transition stage of the two communication states is adopted, and the liquid in the oil port is controlled not to increase or decrease; the electromagnet axially extends from the contact surface to the inside to form an iron core installation cavity, the tail end of the iron core installation cavity is provided with a second cavity, and the second cavity is communicated with the first cavity through a liquid path; the iron core is slidably arranged in the iron core installation cavity in a penetrating way, and one end of the iron core is abutted against the valve core in the first cavity; a third cavity communicated with the valve core mounting cavity is arranged in the auxiliary valve body, the third cavity is communicated with the oil return port through a liquid path, a fourth cavity is further formed in the auxiliary valve body, and the fourth cavity is communicated with the oil inlet through the liquid path; the main spring is installed in the third cavity; the auxiliary spring is arranged in the third cavity and is sleeved outside the main spring, one end of the auxiliary spring is abutted against the auxiliary valve body, and the other end of the auxiliary spring and the main spring are abutted against the valve core together; the piston is slidably arranged in the auxiliary valve body in a penetrating manner, one end of the piston is abutted against the main spring, and the other end of the piston is arranged in the fourth cavity; the oil inlet is communicated with an oil outlet of the pump body; the oil return port is communicated with the oil tank; the control oil port is communicated with the rodless cavity of the variable oil cylinder.

Compared with the prior art, the variable control device of the variable pump can control the variable speed, the variable direction and the displacement of the variable pump, is suitable for mechanical equipment with frequent standby, and solves the problem that the service life of the variable pump is influenced by frequent and rapid variables. Meanwhile, the invention controls the moving speed, the moving direction and the position of the valve core of the variable pump control valve by controlling the current change speed and the current change size of the electromagnet of the variable pump control valve, realizes the control of the moving speed, the moving direction and the position of the variable cylinder piston, further realizes the control of the variable speed, the variable direction and the displacement size of the variable pump, and simultaneously can control the variable pump to keep the effect of low-pressure small-displacement standby state.

Further, the sectional areas of the valve core and the piston are equal, and the equal sectional area means that the difference between the sectional areas of the valve core and the piston is within plus or minus 10% of the sectional area of the valve core.

Furthermore, the device also comprises a main spring guide pad and an auxiliary spring guide pad; the main spring guide pad is arranged between the valve core and the main spring and is sleeved in the main spring, one side of the main spring guide pad is abutted against the valve core, and the other side of the main spring guide pad is abutted against the main spring and the auxiliary spring; the auxiliary spring guide pad is arranged between the main spring and the piston and sleeved in the main spring, one side of the auxiliary spring guide pad is abutted to the main spring, the other side of the auxiliary spring guide pad is abutted to the piston, and the auxiliary spring guide pad can move in the auxiliary spring.

Meanwhile, the invention also provides a variable control method of the variable pump.

A variable pump variable control method is applied to the variable pump variable control device and comprises the following steps:

increasing the current of the variable pump control valve, increasing the thrust of the iron core, moving the valve core rightwards, stopping increasing the current of the variable pump control valve when the control oil port is communicated with the oil inlet, and reducing the displacement of the variable pump at the moment; when the outlet pressure of the variable pump is reduced to a set value, the valve core moves to the middle position, so that the variable pump keeps low-pressure and small-displacement operation and enters a standby state from a working state;

and when the control oil port is communicated with the oil return port, the current of the variable pump control valve is stopped to be reduced, so that the displacement of the variable pump is increased, and the variable pump enters a working state from a standby state.

Furthermore, the movement speed, the movement direction and the position of the valve core are controlled by controlling the current change speed and the current change size of the electromagnet of the variable pump control valve, and the movement speed, the movement direction and the position of the variable oil cylinder piston are further controlled, so that the variable speed, the variable direction and the displacement of the variable pump are controlled, and the switching between the working state and the standby state of the variable pump is realized.

Further, defining:

the ratio of the elastic force of the main spring to the sectional area of the valve core is the pressure generated by the main spring and is set as P1;

the ratio of the elastic force of the auxiliary spring to the sectional area of the valve core is the pressure generated by the auxiliary spring and is set as P2;

the ratio of the thrust of the iron core to the sectional area of the valve core is the pressure generated by the electromagnet and is set as P3;

the liquid pressure of the oil inlet is set to be P4;

when the valve core is in the middle position and the piston is tightly attached to the auxiliary valve body, the ratio of the elastic force of the main spring to the sectional area of the valve core is named as the initial pressure generated by the main spring, and is set as Pa (Pa is lower pressure), and then P1 is set as Pa; the ratio of the elastic force of the auxiliary spring to the sectional area of the valve core is named as initial pressure generated by the auxiliary spring, and is set as Pb, and then P2 is Pb;

by controlling the current of the variable pump control valve, under the condition of P3> Pb, when P4> Pa + Pb-P3, the control oil port is communicated with the oil inlet, and the displacement of the variable pump is reduced; when P4< Pa + Pb-P3, the control oil port is communicated with the oil return port, and the displacement of the variable displacement pump is increased; when P4 is Pa + Pb-P3, the valve core is in the middle position, liquid in a rodless cavity of the variable oil cylinder does not increase or decrease, a piston of the variable oil cylinder stops moving, and the displacement of the variable pump is not changed, so that the variable pump enters a standby state; the current of the variable pump control valve is controlled, so that P3< Pb is achieved, the control oil port is communicated with the oil return port, the displacement of the variable pump is increased, and the variable pump enters a working state.

Further, when the pressure of P4 is greater than Pa, the current of the variable pump control valve is controlled to increase, the thrust of the iron core can be increased, the valve core moves rightwards, the through holes of the control oil port and the oil return port are reduced, and then the through holes of the control oil port and the oil inlet are increased, so that the displacement of the variable pump is changed from large to small; the current of the variable pump control valve is controlled to be reduced, the thrust of an iron core can be reduced, the valve core moves leftwards, the through holes of the control oil port and the oil inlet are reduced, and then the through holes of the control oil port and the oil return port are increased, so that the displacement of the variable pump is changed from small to large.

For a better understanding and practice, the invention is described in detail below with reference to the accompanying drawings.

Drawings

FIG. 1 is a schematic diagram of a prior art variable displacement pump hydraulic system;

FIG. 2 is a schematic diagram of a variable pump variable control apparatus of the present invention;

FIG. 3 is a sectional view showing the structure of a variable pump control valve;

the reference numbers in the figures illustrate: 1. a main valve body; 2. an electromagnet; 3. a sub-valve body; 4. a valve core; 5. an iron core; 6. a main spring; 7. a secondary spring; 8. a piston; 9. an end cap; 10. a main spring guide pad; 11. a secondary spring guide pad; 12. a sealing plug; 20. a valve core mounting cavity; 21. an oil inlet; 22. a control oil port; 23. an oil return port; 24. a first cavity; 25. a second cavity; 26. a third cavity; 27. a fourth cavity; 30. an oil tank; 31. a variable pump control valve; 32. a pump body; 33. and a variable oil cylinder.

Detailed Description

Referring to fig. 2-3, fig. 2 is a schematic diagram of a variable pump control device according to the present invention, and fig. 3 is a sectional view of a variable pump control valve.

The variable pump variable control device comprises an oil tank 30, a variable pump and a variable pump control valve 31, wherein the variable pump comprises a pump body 32 and a variable oil cylinder 33; the variable pump control valve 31 comprises a main valve body 1, an electromagnet 2, an auxiliary valve body 3, a valve core 4, an iron core 5, a main spring 6, an auxiliary spring 7, a piston 8 and an end cover 9; the main valve body 1 is provided with a valve core installation cavity 20 along the axial direction, and an oil inlet 21, a control oil port 22 and an oil return port 23 which are respectively communicated with the valve core installation cavity 20 along the radial direction; one side end face of the main valve body 1 is hermetically connected with the electromagnet 2, a first cavity 24 communicated with the valve core installation cavity 20 is formed in the contact surface, and the first cavity 24 is communicated with the oil inlet 21 through a liquid path; the other end face of the main valve body 1 is hermetically connected with the auxiliary valve body 3; the valve core 4 penetrates through the valve core mounting cavity 20 and can move in the valve core mounting cavity 20, so that the oil inlet 21 is communicated with the control oil port 22 or the control oil port 22 is communicated with the oil return port 23; when the valve core 4 is in the middle position, the two communication states are in a transition stage, and the liquid in the control oil port 22 is not increased or decreased; the electromagnet 2 is provided with an iron core installation cavity extending axially from the contact surface to the inside, the tail end of the iron core installation cavity is provided with a second cavity 25, and the second cavity 25 is communicated with the first cavity 24 through a liquid path; the iron core 5 is slidably arranged in the iron core installation cavity in a penetrating way, and one end of the iron core 5 is fixedly connected with the valve core 4 in the first cavity 24; the end cover 9 is arranged at the tail part of the auxiliary valve body 3; a third cavity 26 communicated with the valve core installation cavity 20 is arranged in the auxiliary valve body 3, the third cavity 26 is communicated with the oil return port 23 through a liquid path, a fourth cavity 27 is formed between the auxiliary valve body 3 and the end cover 9, and the fourth cavity 27 is communicated with the oil inlet 21 through a liquid path; the main spring 6 is mounted in the third cavity 26; the auxiliary spring 7 is arranged in the third cavity 26 and is sleeved outside the main spring 6, one end of the auxiliary spring is abutted against the auxiliary valve body 3, and the other end of the auxiliary spring and the main spring 6 are abutted against the valve core 4 together; the piston 8 is slidably arranged in the auxiliary valve body 3 in a penetrating manner, one end of the piston is abutted against the main spring 6, and the other end of the piston is arranged in the fourth cavity 27; the oil inlet 21 is communicated with an oil outlet of the pump body 32; the oil return port 23 is communicated with the oil tank 30; the control oil port 22 is communicated with a rodless cavity of the variable oil cylinder 33. Preferably, the valve core 4 and the piston 8 have the same cross-sectional area, and the difference between the cross-sectional areas of the valve core 4 and the piston 8 is within plus or minus 10% of the cross-sectional area of the valve core 4.

The device also comprises a main spring guide pad 10 and an auxiliary spring guide pad 11; the main spring guide pad 10 is arranged between the valve core 4 and the main spring 6 and is sleeved in the main spring 6, one side of the main spring guide pad is abutted against the valve core 4, the other side of the main spring guide pad is abutted against the main spring 6 and the auxiliary spring 7, and a limit groove is arranged on the main spring guide pad to limit the main spring 6 and the auxiliary spring 7; the auxiliary spring guide pad 11 is installed between the main spring 6 and the piston 8 and sleeved in the main spring 6, one side of the auxiliary spring guide pad is abutted to the main spring 6, the other side of the auxiliary spring guide pad is abutted to the piston 8, and the auxiliary spring guide pad 11 can move in the auxiliary spring 7. Further, the auxiliary valve body 3 is provided with a sealing plug 12, an oil hole communicated with the fourth cavity 27 is formed in the auxiliary valve body 3, and the sealing plug 12 is plugged in the oil hole.

Further, the device is controlled by a control unit (not shown), and the control unit controls the current magnitude and the change speed of the variable pump control valve 31 according to the working condition of the variable pump. The control unit may be a PLC (programmable logic controller) or a proportional amplifier.

For the convenience of description of the working principle, the following are defined in the present case:

the ratio of the elastic force of the main spring to the sectional area of the valve core is named as pressure generated by the main spring and is set as P1;

the ratio of the elastic force of the auxiliary spring to the sectional area of the valve core is named as the pressure generated by the auxiliary spring and is set as P2;

the ratio of the thrust of the iron core to the sectional area of the valve core is named as the pressure generated by the electromagnet and is set as P3;

the liquid pressure at the oil inlet is set to P4.

Specifically, when the valve core is at the middle position and the piston is tightly attached to the auxiliary valve body, the ratio of the elastic force of the main spring to the sectional area of the valve core is named as the initial pressure generated by the main spring, and is set as Pa (Pa is a lower pressure), and then P1 is Pa; the ratio of the elastic force of the auxiliary spring to the cross-sectional area of the valve element is named as the initial pressure generated by the auxiliary spring, and is set as Pb, and then P2 is Pb.

The sum of the pressures at the left end of the valve core is P3+ P4, and the sum of the pressures at the right end of the valve core is P1+ P2; because the sectional areas of the valve core and the small piston are equal, the pressure at the left end of the piston is P1, and the pressure at the right end of the piston is P4. The direction of movement, speed of movement and position of the spool and piston are dependent on the changes in P1, P2, P3 and P4.

In practical application, when mechanical equipment powered by the variable pump is in a working state, the variable pump supplies high-pressure large-flow oil. When the variable pump enters the standby state, mechanical equipment generally enters the standby state firstly, the variable pump enters the standby state later, in a time period between the two standby states, the mechanical equipment does not consume energy, the variable pump supplies energy at the maximum displacement, the pressure of the liquid at the outlet of the variable pump generally depends on an energy accumulator or a safety overflow valve in the mechanical equipment, and the pressure is a large value. I.e., the variable displacement pump is in operation and is about to enter a standby state, P4 is still much greater than Pa.

The specific working process is as follows:

when the variable pump needs to enter a standby state from a working state, the mechanical equipment does not consume energy in a time period between the mechanical equipment and the variable pump which enter the standby state and the variable pump sequentially, the variable pump still supplies energy at the maximum displacement, the pressure of liquid at the outlet of the variable pump generally depends on an energy accumulator or a safety overflow valve in the mechanical equipment, and the pressure is a large value, namely P4 is far larger than Pa. At this time, P4 acts on the left end of the spool and the right end of the piston to make them press the main spring with equal pressure, the pressure P1 generated by the main spring is equal to P4, the pressure P1 at the right end of the spool is equal to the pressure P4 at the left end, and therefore the position of the spool is determined by P2 and P3. In this state, the pressure P3 generated by the plunger of the solenoid of the controlled variable pump control valve is set to a small value, i.e., P3< Pb. Since P2 is Pb when the spool is in the neutral position, the spool position is at the left end, i.e., the variable pump control valve control port and the return port are in communication. At this time, the current of the electromagnet is gradually increased, the pressure P3 generated by the iron core is also gradually increased, and when the pressure P3 is increased to a certain value, the pressure P2 is overcome to push the valve core to move rightwards. And the current continues to increase until the oil inlet is communicated with the control oil port to a certain extent, namely when the P3 is slightly larger than Pb, the current stops increasing and maintains the current value. The oil outlet of the variable pump is communicated with the rodless cavity of the variable oil cylinder through the oil inlet and the control oil port of the variable pump control valve, and the rod cavity of the variable oil cylinder is communicated with the oil outlet of the variable pump all the time. However, the area of the rodless cavity of the variable oil cylinder is larger than that of the rod cavity, the reset spring force of the rod cavity of the variable oil cylinder is relatively small and can be ignored, so that the pressure of the rodless cavity of the variable oil cylinder is larger than that of the rod cavity, and the piston of the variable oil cylinder moves leftwards to push the swing of the variable pump to reduce the displacement of the variable pump.

When the displacement is reduced to a certain value, the liquid pressure P4 at the outlet of the variable pump is reduced subsequently, the force of the valve core and the piston for extruding the main spring of the control valve 4 of the variable pump is also reduced, the main spring extends rightwards, the piston moves rightwards until clinging to the auxiliary valve body, and the position of the valve core is unchanged. At the moment, P4 continues to decrease, the main spring extends leftwards, the valve core is pushed by the spring to move leftwards until the valve core is in the middle position, the liquid in the rodless cavity of the variable oil cylinder does not increase or decrease, the piston in the variable oil cylinder stops moving, the displacement of the variable pump keeps unchanged, P4 stops decreasing, the valve core stops moving, and the valve core enters a low-pressure small-displacement standby state. At this time the theoretical value of P4 is equal to Pa + Pb-P3, but since P3 is only slightly larger than Pb, it can be considered that P4 is approximately equal to Pa and the outlet pressure when the variable displacement pump enters the low pressure small displacement standby state is maintained at Pa.

When the variable pump is required to enter a working state, the current of the electromagnet is gradually reduced, the pressure P3 generated by the electromagnet on the iron core is gradually reduced, when P3 is slightly less than Pb, the oil tank is communicated with the rodless cavity of the variable oil cylinder through the oil return port and the control oil port of the control valve of the variable pump, because the oil tank 2 is close to zero pressure, liquid in the rodless cavity of the variable oil cylinder starts to flow into the oil tank, and the piston of the variable oil cylinder moves to the right under the action of the liquid pressure of the rod cavity and the spring to push the swing of the variable pump to increase the displacement of the variable pump. At the same time, as variable pump outlet liquid pressure P4 rises, the piston moves to the left, compressing the main spring, keeping P1 and P4 equal and the spool position unaffected by P1 and P4. The displacement of the variable displacement pump eventually increases to a maximum state, energizing the mechanical device, and the variable displacement pump enters an operational state. When the variable pump is required to enter the standby state again, the current of the electromagnet is controlled to be gradually increased, and the standby state and the working state of the variable pump can be switched repeatedly.

In the whole circulation process, the current of the electromagnet of the variable pump control valve can be steplessly adjusted in size and change speed by using a PLC and a proportional amplifier, so that the pressure P3 generated by the electromagnet of the variable pump control valve can be randomly adjusted in size and change speed, the variable direction and the variable speed of the variable pump can be controlled while the standby state and the working state of the variable pump are repeatedly switched, the problem that the service life of the variable pump is influenced by quick variables is solved, and the standby control device of the variable pump is obtained and is suitable for the variable pump which is frequently in standby.

In addition, based on the variable pump variable control device, the invention also provides a control method of the device. The variable control method of the variable pump comprises the following steps:

increasing the current of the variable pump control valve, increasing the thrust of the iron core, moving the valve core rightwards, stopping increasing the current of the variable pump control valve when the control oil port is communicated with the oil inlet, and reducing the displacement of the variable pump at the moment; when the outlet pressure of the variable pump is reduced to a set value, the valve core moves to the middle position, so that the variable pump keeps low-pressure and small-displacement operation and enters a standby state from a working state;

and when the control oil port is communicated with the oil return port, the current of the variable pump control valve is stopped to be reduced, so that the displacement of the variable pump is increased, and the variable pump enters a working state from a standby state.

In the control process, the movement speed, the movement direction and the position of the valve core are controlled by controlling the current change speed and the current change size of the electromagnet of the variable pump control valve, and the movement speed, the movement direction and the position of the variable oil cylinder piston are further controlled, so that the variable speed, the variable direction and the displacement of the variable pump are controlled, and the working state and the standby state of the variable pump can be switched.

The invention is suitable for mechanical equipment with frequent standby, and solves the problem of short service life of the variable pump caused by frequent standby.

The Pa value is not adjustable, and the adjusting function of the Pa value is added on the basis of the invention, belonging to the patent action of using the invention; the position of the auxiliary spring in the invention is not limited to the position shown in the attached figures 2-3, the function of the invention can be realized as long as the elastic force of the auxiliary spring is opposite to the thrust direction of the iron core, and the resultant force of the auxiliary spring and the iron core directly or indirectly acts on the valve core, and the function of the invention realized by changing the position of the auxiliary spring belongs to the protection scope of the invention.

The above-mentioned embodiments only express one embodiment of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, to those skilled in the art, changes and modifications may be made without departing from the spirit of the present invention, and it is intended that the present invention encompass such changes and modifications.

Claims (7)

1. A variable pump variable control device comprises an oil tank, a variable pump and a variable pump control valve, wherein the variable pump comprises a pump body and a variable oil cylinder; the method is characterized in that:

the variable pump control valve comprises a main valve body, an electromagnet, an auxiliary valve body, a valve core, an iron core, a main spring, an auxiliary spring and a piston; the main valve body is provided with a valve core mounting cavity along the axial direction, and an oil inlet, a control oil port and an oil return port which are respectively communicated with the valve core mounting cavity along the radial direction; the end face of one side of the main valve body is hermetically connected with the electromagnet, a first cavity communicated with the valve core mounting cavity is formed in the contact surface, and the first cavity is communicated with the oil inlet through a liquid path; the end face of the other side of the main valve body is connected with the auxiliary valve body in a sealing way; the valve core penetrates through the valve core mounting cavity and can move in the valve core mounting cavity, so that the communication between the oil inlet and the control oil port or the communication between the control oil port and the oil return port is realized; when the valve core is in the middle position, the transition stage of the two communication states is adopted, and the liquid in the oil port is controlled not to increase or decrease; the electromagnet axially extends from the contact surface to the inside to form an iron core installation cavity, the tail end of the iron core installation cavity is provided with a second cavity, and the second cavity is communicated with the first cavity through a liquid path; the iron core is slidably arranged in the iron core installation cavity in a penetrating way, and one end of the iron core is abutted against the valve core in the first cavity; a third cavity communicated with the valve core mounting cavity is arranged in the auxiliary valve body, the third cavity is communicated with the oil return port through a liquid path, a fourth cavity is further formed in the auxiliary valve body, and the fourth cavity is communicated with the oil inlet through the liquid path; the main spring is installed in the third cavity; the auxiliary spring is arranged in the third cavity and is sleeved outside the main spring, one end of the auxiliary spring is abutted against the auxiliary valve body, and the other end of the auxiliary spring and the main spring are abutted against the valve core together; the piston is slidably arranged in the auxiliary valve body in a penetrating manner, one end of the piston is abutted against the main spring, and the other end of the piston is arranged in the fourth cavity;

the oil inlet is communicated with an oil outlet of the pump body; the oil return port is communicated with the oil tank; the control oil port is communicated with the rodless cavity of the variable oil cylinder.

2. The variable pump variable control device according to claim 1, characterized in that: the sectional areas of the valve core and the piston are equal, and the equal sectional area is that the difference between the sectional areas of the valve core and the piston is within plus or minus 10 percent of the sectional area of the valve core.

3. The variable pump variable control device according to claim 1, characterized in that: the spring guide device also comprises a main spring guide pad and an auxiliary spring guide pad; the main spring guide pad is arranged between the valve core and the main spring and is sleeved in the main spring, one side of the main spring guide pad is abutted against the valve core, and the other side of the main spring guide pad is abutted against the main spring and the auxiliary spring; the auxiliary spring guide pad is arranged between the main spring and the piston and sleeved in the main spring, one side of the auxiliary spring guide pad is abutted to the main spring, the other side of the auxiliary spring guide pad is abutted to the piston, and the auxiliary spring guide pad can move in the auxiliary spring.

4. A variable control method of a variable pump is characterized in that: the variable pump variable control device applied to any one of claims 1 to 3, comprising the steps of:

increasing the current of the variable pump control valve, increasing the thrust of the iron core, moving the valve core rightwards, stopping increasing the current of the variable pump control valve when the control oil port is communicated with the oil inlet, and reducing the displacement of the variable pump at the moment; when the outlet pressure of the variable pump is reduced to a set value, the valve core moves to the middle position, so that the variable pump keeps low-pressure and small-displacement operation and enters a standby state from a working state;

and when the control oil port is communicated with the oil return port, the current of the variable pump control valve is stopped to be reduced, so that the displacement of the variable pump is increased, and the variable pump enters a working state from a standby state.

5. The variable pump variable control method of claim 4, wherein: the movement speed, the movement direction and the position of the valve core are controlled by controlling the current change speed and the current change size of the electromagnet of the variable pump control valve, and the movement speed, the movement direction and the position of the variable cylinder piston are further controlled, so that the variable speed, the variable direction and the displacement of the variable pump are controlled, and the working state and the standby state of the variable pump can be switched.

6. The variable pump variable control method of claim 4, defining:

the ratio of the elastic force of the main spring to the sectional area of the valve core is the pressure generated by the main spring and is set as P1;

the ratio of the elastic force of the auxiliary spring to the sectional area of the valve core is the pressure generated by the auxiliary spring and is set as P2;

the ratio of the thrust of the iron core to the sectional area of the valve core is the pressure generated by the electromagnet and is set as P3;

the liquid pressure of the oil inlet is set to be P4;

when the valve core is in the middle position and the piston is tightly attached to the auxiliary valve body, the ratio of the elastic force of the main spring to the sectional area of the valve core is named as the initial pressure generated by the main spring, and is set as Pa, and Pa is lower pressure, so that P1 is Pa; the ratio of the elastic force of the auxiliary spring to the sectional area of the valve core is named as initial pressure generated by the auxiliary spring, and is set as Pb, and then P2 is Pb;

the method is characterized in that: by controlling the current of the variable pump control valve, under the condition of P3> Pb, when P4> Pa + Pb-P3, the control oil port is communicated with the oil inlet, and the displacement of the variable pump is reduced; when P4< Pa + Pb-P3, the control oil port is communicated with the oil return port, and the displacement of the variable displacement pump is increased; when P4 is Pa + Pb-P3, the valve core is in the middle position, liquid in a rodless cavity of the variable oil cylinder does not increase or decrease, a piston of the variable oil cylinder stops moving, and the displacement of the variable pump is not changed, so that the variable pump enters a standby state;

the current of the variable pump control valve is controlled, so that P3< Pb is achieved, the control oil port is communicated with the oil return port, the displacement of the variable pump is increased, and the variable pump enters a working state.

7. The variable pump variable control method of claim 4, wherein: when P4 is greater than Pa, the current of the variable pump control valve is controlled to increase, the thrust of an iron core can be increased, the valve core moves rightwards, the through holes of the control oil port and the oil return port are reduced, then the through holes of the control oil port and the oil inlet are increased, and therefore the displacement of the variable pump is changed from large to small; the current of the variable pump control valve is controlled to be reduced, the thrust of an iron core can be reduced, the valve core moves leftwards, the through holes of the control oil port and the oil inlet are reduced, and then the through holes of the control oil port and the oil return port are increased, so that the displacement of the variable pump is changed from small to large.

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