Flow control valve

Abstract

The utility model relates to a flow control valve, which belongs to the technical application field of hydraulic plunger pumps and comprises a valve body, a push rod arranged in the valve body, a valve core partially arranged in the valve body and capable of providing stable output force for the push rod, and an electromagnet arranged at one end of the valve body and capable of driving the valve core to move in the valve body. After the pressure difference of the flow valve of the load-sensitive pump is set, current is output to the electromagnet through the electric controller, the electromagnet keeps constant output force under the corresponding current and acts on the left side of the balance valve element through the push rod, equivalently, the set pressure difference is reduced, the output flow of the load-sensitive plunger pump is reduced, and the purposes of equipment micro-motion or accurate control are achieved.

Description

Technical Field

[0001] The utility model belongs to the technical application field of hydraulic plunger pumps and relates to a flow control valve. Background Art

[0002] Load sensing hydraulic system is suitable for flow adaptation circuit, especially for the occasions where multiple actuators are required to act simultaneously with high coordination, and the number of actuators can be increased or decreased at will. The load sensing circuit can automatically adjust the output flow of the load sensitive pump according to the flow required by the actuator, so the energy saving effect is very significant. The most typical application is the multi-working device application of small excavators, so the load sensing system is the mainstream hydraulic system currently used in small and medium-sized excavators.

[0003] The load-sensing plunger pump is the main component in the load sensing system. The flow control valve in the load-sensing plunger pump receives the load pressure signal. By adjusting the flow control valve spring, the load pressure and the pump outlet pressure form a fixed pressure difference at the flow valve. The fixed pressure difference is compared with the pressure difference formed on the load-sensing valve core between the load pressure and the pump outlet pressure, thereby controlling the output of the load-sensing pump flow. Figure 1 It is a schematic diagram of the structure of a traditional load-sensitive plunger pump flow control valve module, 1' is a balancing valve core, 2' is a control oil port, 3' is a flow control valve receiving load signal oil port, 4' is a flow control valve adjusting pressure difference screw, 5' is the first plunger pump outlet pressure oil port, 6' is the second plunger pump outlet pressure oil port, and 7' is the flow control valve body. Figure 2 This is the hydraulic principle diagram of the traditional load sensing pump, combined with Figure 1 , 2 A brief description is given of how the flow control valve controls the output flow of a load-sensitive plunger pump.

[0004] The outlet pressure oil pressure P of the plunger pump acts on the left end face of the balance valve core 1' through the first plunger pump outlet pressure oil port 5', generating a force F1 to the right on the action area, and the load signal oil pressure PL sThe load signal oil port 3' received by the flow control valve acts on the right end of the balance valve core 1', generating a force F2 to the left on the action area. For the balance valve core 1', the balance relationship at this time is F1 = F2 + F3, where F3 is the spring force, F3 = F1-F2 = ΔP1, ΔP1 is the pressure difference between the pump outlet pressure and the load pressure at the flow valve, which is a constant value. Assuming that the pressure difference is ΔP1, the output flow of the plunger pump is Q1. It should be noted that the spring force F3 can be adjusted by adjusting the pressure difference screw 4' of the right flow control valve, and the pressure difference and flow can be adjusted by adjusting the pressure difference screw 4' of the flow control valve. When the balance valve core 1' is in the balance position, the control oil port 2' is covered by the shoulder of the balance valve core 1', and the plunger pump outlet pressure oil on standby at the second plunger pump outlet pressure oil port 6' cannot enter the variable chamber through the control oil port 2', and the plunger pump cannot achieve variable.

[0005] like Figure 2 The throttle valve core port shown is a throttling opening formed by the load-sensitive valve core and the valve body. The oil pressures before and after the flow passes through the throttle valve core port are the load-sensitive pump outlet pressure and the load pressure, respectively. The pressure difference ΔP2 formed by the throttle valve core port is P-PL s The throttling opening formed by the valve core and the valve body on the load-sensing valve is controlled by the angle of the pilot handle operated by the user. The specific control logic is that the larger the working angle of the pilot handle, the larger the throttling opening, the weaker the throttling effect, the smaller the pressure difference formed through the throttling port, and the system expects the load-sensing pump to output at a large flow rate; the smaller the working angle of the pilot handle, the smaller the throttling opening, the stronger the throttling effect, the larger the pressure difference formed through the throttling port, and the system expects the load-sensing pump to output at a smaller flow rate.

[0006] When ΔP2 = ΔP1, the load-sensitive variable pump flow valve core is in a balanced position, and the plunger pump output flow is a certain set fixed value. When the pilot handle angle increases, PL s is the load pressure, which remains unchanged. As the throttle port becomes larger, the throttling effect becomes weaker. At this time, the pressure difference ΔP2 formed at the main valve decreases, and ΔP2 = P-PL s It can be seen that the oil pressure P at the pump outlet becomes smaller. At this time, for the flow valve at the load-sensitive plunger pump, F3=F1-F2=ΔP1. Since the pressure difference ΔP1 is set by the adjusting spring, the oil pressure P acting on the left end of the balancing valve core 1' becomes smaller, so the balance of the balancing valve core 1' is broken, and the balancing valve core 1' moves to the left. The plunger pump outlet pressure oil on standby at the second plunger pump outlet pressure oil port 6' cannot enter the variable chamber through the control oil port 2', and the plunger pump outputs at a fixed flow rate greater than the set value under the action of the reset spring.

[0007] When the pilot handle angle becomes smaller, PL sThe load pressure remains unchanged. As the throttle port becomes smaller, the throttling effect is stronger. At this time, the pressure difference ΔP2 formed at the main valve decreases, and ΔP2 = P-PL s It can be seen that the oil pressure P at the pump outlet increases. At this time, for the flow valve at the load-sensitive plunger pump, F3=F1-F2=ΔP1. Since the pressure difference ΔP1 is set by adjusting the spring, the oil pressure P acting on the left end of the balancing valve core 1' increases, so the balance of the balancing valve core 1' is broken, and the balancing valve core 1' moves to the right. The outlet pressure oil of the plunger pump on standby at the second plunger pump outlet pressure oil port 6' enters the variable chamber through the control oil port 2', and the plunger pump outputs at a small flow rate under the action of the load oil pressure P.

[0008] The essence of the operation of the load-sensitive plunger pump flow control valve is that the fixed pressure difference ΔP1 formed by the pump outlet pressure and the load pressure at the flow valve is compared with the changing pressure difference ΔP2 formed by the pump outlet pressure and the load pressure on the load-sensitive valve. When ΔP1 is greater than ΔP2, the load-sensitive pump outputs at a larger flow rate until the pressure difference is rebalanced. At this time, the output flow rate of the load-sensitive pump is higher than the original set flow rate; when ΔP1 is less than ΔP2, the load-sensitive pump outputs at a smaller flow rate until the pressure difference is rebalanced. At this time, the output flow rate of the load-sensitive pump is lower than the original set flow rate.

[0009] It can be seen that in the load-sensitive control system, the output flow of the load-sensitive pump is only related to the pressure difference, but has nothing to do with the load size. After the flow valve pressure differential adjustment screw sets a fixed pressure difference, the throttling opening size formed by the load-sensitive valve spool and the valve body is changed by operating the pilot handle to change the pressure difference ΔP2 to control the output of the load-sensitive pump flow, and the flow output characteristics of the load-sensitive pump are determined. However, for equipment in a small space or that requires slow micro-motion operations, this control method of controlling the flow output of the load-sensitive pump by operating the angle of the pilot handle cannot meet the requirements of working conditions. This control method has high requirements on the accuracy of the pilot handle to control the flow output of the load-sensitive pump, and also has very strict requirements on the driver's operating skills. Therefore, if you are not careful, it may cause accidents such as collisions. Utility Model Content

[0010] The purpose of the utility model is to propose a flow control valve with simple structure, low manufacturing cost and strong economical use, so as to solve the problems that the existing flow control valve cannot achieve high-precision flow output and small flow output under special working conditions, thereby cannot achieve micro-operation, and has high requirements on the operating skills of the operators.

[0011] In order to achieve the above-mentioned purpose, the technical solution of the utility model provides a flow control valve, including a valve body, a push rod arranged in the valve body, a valve core partially arranged in the valve body and capable of providing a stable output force for the push rod, and an electromagnet arranged at one end of the valve body and capable of driving the valve core to move in the valve body.

[0012] Preferably, after the electromagnet is energized, the valve core extends a fixed stroke under the corresponding current to provide a stable output force acting on the push rod end face; at this time, the force on the left side of the balancing valve core is greater than the force on the right side, and the balancing valve core moves to the right, and the pump outlet oil pressure on standby at the second oil channel of the valve body enters the variable plunger chamber of the load-sensitive pump through the third oil channel, pushing the plunger pump swash plate angle to become smaller, and the plunger pump outputs at a smaller flow rate.

[0013] Preferably, the push rod is placed in the valve body and can slide, one end of the push rod is in contact with the valve core, and the other end is in contact with the end surface of the balance valve core.

[0014] Preferably, a valve sleeve is provided in the valve body, and the balancing valve core is provided in the valve sleeve; the valve body and the valve sleeve are respectively provided with a step surface and a shoulder, and the step surface and the shoulder cooperate to limit the movement of the valve sleeve toward the direction where the push rod is located.

[0015] Preferably, the valve sleeve is provided with a spacer sleeve at one end away from the push rod, a ball pin is provided in the spacer sleeve, and a section of the ball pin plane is in contact with the end surface of the balancing valve core.

[0016] Preferably, a nut is provided on a side of the spacer away from the push rod, two opposite spring seats are provided in the nut, and a spring is provided between the two spring seats.

[0017] Preferably, the end surfaces of the two spring seats that are away from each other are both provided with concave arc surfaces.

[0018] Preferably, the spring comprises a small spring and a large spring, and the large spring is sleeved on the outer circumference of the small spring.

[0019] Preferably, an adjusting screw is provided at one end of the nut away from the valve sleeve.

[0020] Preferably, one of the concave arc surfaces of the two spring seats is tangent to the spherical end of the ball pin, and the other concave arc surface is tangent to the spherical end of the adjusting screw.

[0021] The beneficial effects brought by the utility model are:

[0022] 1. After the pressure difference ΔP1 of the load-sensitive pump flow valve is set, the electric controller outputs current to the electromagnet. The electromagnet maintains a constant output force under the corresponding current, and acts on the left side of the balancing valve core through the push rod, which is equivalent to reducing the set pressure difference ΔP1, reducing the output flow of the load-sensitive plunger pump, and achieving the purpose of micro-motion or precise control of the equipment.

[0023] 2. Simple structure, few parts, low processing and manufacturing cost, very easy to assemble, and very practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of a conventional load-sensitive plunger pump flow control valve;

[0025] Figure 2 This is the control hydraulic principle diagram of a traditional load-sensing plunger pump;

[0026] Figure 3 The present invention is a structural schematic diagram of a flow control valve provided by the utility model.

[0027] Reference numerals:

[0028] 1. Electromagnet; 2. Push rod; 3. First oil passage; 4. Second oil passage; 5. Third oil passage; 6. Valve body; 7. Spacer; 8. Ball pin; 9. Spring seat; 10. Large spring; 11. Balance valve core; 12. Valve sleeve; 13. Load signal receiving oil port; 14. Small spring; 15. Nut; 16. Adjusting screw; 17. Valve core;

[0029] 1', balance valve core; 2' control oil port; 3' flow control valve receiving load signal oil port; 4', flow control valve adjusting pressure difference screw; 5', first plunger pump outlet pressure oil port; 6', second plunger pump outlet pressure oil port; 7', flow control valve body. DETAILED DESCRIPTION

[0030] The specific implementation methods of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these implementation methods is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each implementation method of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] See attached Figure 3The embodiment of the utility model discloses a flow control valve. The electromagnet 1 is screwed and installed on the valve body 6, and the push rod 2 is placed in the hole of the valve body 6 and can move flexibly left and right. One end of the push rod 2 contacts the end face of the valve core 17 driven by the electromagnet 1, and the other end contacts the end face of the balance valve core 11. The valve sleeve 12 is installed in the valve body 6, and the right shoulder is fitted with the step surface of the valve body 6 to limit the freedom of the valve sleeve 12 to the left. The balance valve core 11 is placed in the valve sleeve 12 and can move freely and flexibly in the left and right directions.

[0032] The spacer sleeve 7 is installed in the valve sleeve 12 and limited by the shoulder. The ball pin 8 is placed in the spacer sleeve 7, with one end of the plane in contact with the end face of the balance valve core 11, and one end of the spherical surface tangent to the concave arc surface of the spring seat 9. The nut 15 is locked on the valve body 6 by threads and is limited by the right end face of the valve sleeve 12, while limiting the freedom of the valve sleeve 12 to the right and the freedom of the nut 15 to the left. The adjusting screw 16 cooperates with the nut 15, and the left spherical surface is tangent to the concave spherical surface of the spring seat 9.

[0033] The first oil passage 3 and the second oil passage 4 are both hydraulic oil passages for the outlet of the load sensing pump, and the third oil passage 5 is a hydraulic oil passage leading to the variable chamber of the load sensing pump. The valve body 6 is a flow control valve body, and the two opposite spring seats 9 are used to support the large spring 10 and the small spring 14.

[0034] After the pressure difference of the load-sensitive pump flow valve is set, the electric controller outputs current to the electromagnet 1. The electromagnet 1 maintains a constant output force under the corresponding current, and acts on the left side of the balance valve core 11 through the push rod 2, which is equivalent to reducing the set pressure difference, thereby reducing the output flow of the load-sensitive plunger pump, and achieving the purpose of micro-movement or precise control of the equipment.

[0035] Combination Figure 2 , 3 A control process of a flow control valve provided by the utility model is described.

[0036] For the balancing valve core 11, when the solenoid valve is not energized, the oil pressure at the outlet of the load-sensing pump acts on the left side of the balancing valve core 11 through the first oil passage 3, forming a rightward force F1 on the balancing valve core. The load signal oil pressure PL s By receiving the load signal oil port 13, the right end of the balance valve core is acted on, forming a leftward force F2 on the balance valve core. By adjusting the screw 16, the large and small springs are compressed, and a leftward force F3 is generated on the balance valve core. When the balance valve core is balanced, it can be known that F1 = F2 + F3, where F3 is the spring force.

[0037] F3=F1-F2=ΔP1, ΔP1 is the pressure difference between the pump outlet pressure and the load pressure at the flow valve, which is a constant value. Assuming that the pressure difference is ΔP1, the output flow of the plunger pump is Q1. At this time, the pump outlet oil pressure on standby in the second oil channel 4 is blocked by the shoulder of the balance valve core and cannot enter the variable servo chamber through the third oil channel 5. The load-sensitive pump cannot achieve variable. When the operating angle of the pilot handle increases, the throttling opening on the load-sensitive main valve core becomes larger, the throttling effect becomes weaker, and the pressure difference ΔP2 formed through the throttling port becomes smaller. ΔP2=P-PL s It can be seen that the load pressure at the pump outlet decreases, the balance valve core moves to the left, and the pump outlet oil pressure cannot enter the variable chamber through the third oil channel 5. Under the action of the return spring of its own variable servo chamber, the plunger pump outputs flow at a large flow state. When the operating angle of the pilot handle becomes smaller, the throttling opening on the load-sensitive main valve becomes smaller, the stronger the throttling effect, the greater the pressure difference ΔP2 formed through the throttling port, and ΔP2=P-PL s It can be seen that the load pressure at the pump outlet increases, the balance valve core moves to the right, the pump outlet oil pressure enters the variable chamber through the third oil channel 5, and the plunger pump outputs flow at a small flow rate.

[0038] It can be seen that after the flow valve pressure differential adjusting screw 16 sets a fixed pressure differential ΔP1, the size of the throttling opening formed by the load-sensitive valve core and the valve body can be changed by operating the pilot handle, thereby changing the pressure differential ΔP2 to control the output flow of the load-sensitive pump. The flow output characteristics of the load-sensitive pump are determined accordingly, which can be understood as the operating angle and amplitude of the pilot handle directly affecting and controlling the output flow of the load-sensitive pump. This control method has disadvantages in certain working conditions. For example, in a small working space, to achieve precise flow and micro-motion control, strict requirements are placed on the operator's familiarity with the control handle and the accuracy of the system flow feedback. A slight careless control may very likely cause a collision accident.

[0039] The utility model adds an electromagnet module on the left side of the load-sensitive pump flow control valve. After the electromagnet is energized, the self-contained valve core in the electromagnet extends out. Under the corresponding current, the valve core extends a fixed stroke to provide a stable output force acting on the left end face of the push rod 2. At this time, the following relationship F4+F1=F2+F3 is established for the balance valve core. F4 is the steady-state force output by the electromagnet under a certain current value. Then, at this time, the force on the left side of the balance valve core is greater than the force on the right side. The balance valve core moves to the right, and the pump outlet oil pressure on standby at the second oil channel 4 enters the variable plunger cavity of the load-sensitive pump through the third oil channel 5, pushing the plunger pump swash plate angle to become smaller, and the plunger pump outputs at a smaller flow rate. The greater the current provided to the electromagnet, the greater the output force, and the smaller the flow rate output by the plunger pump. Therefore, under this control logic, when the equipment is in a certain working condition and needs to provide a small flow rate to realize micro-control operation, by triggering the electric control button in the cab, the electromagnet on the load-sensitive pump can be provided with current, and the load-sensitive pump outputs at a small flow rate to realize micro-motion, precision and other action control.

[0040] The utility model is based on the structure of the existing load-sensitive pump flow control valve, and realizes the output of accurate flow and small flow of the load-sensitive pump by adding an electronic control module, and realizes the micro-operation of the equipment. When the equipment is operating under a specific working condition, it only needs to manually trigger the electronic control switch. At this time, even if the operating angle of the pilot handle is large, the load-sensitive pump still outputs at a small flow rate, ensuring that the equipment operates accurately and controllably when operating in a small space or under lifting conditions, avoiding collision accidents caused by unskilled driving skills, large amplitude of the operating handle, or accidental contact with the operating handle.

[0041] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A flow control valve, characterized in that: The invention comprises a valve body (6), a push rod (2) arranged in the valve body (6), a valve core (17) which is partially arranged in the valve body (6) and can provide a stable output force for the push rod (2), and an electromagnet (1) which is arranged at one end of the valve body (6) and can drive the valve core (17) to move in the valve body (6).

2. A flow control valve according to claim 1, characterized in that: The push rod (2) is placed in the valve body (6) and is slidable. One end of the push rod (2) contacts the valve core (17), and the other end contacts the end surface of the balance valve core (11).

3. A flow control valve according to claim 2, characterized in that: A valve sleeve (12) is provided in the valve body (6), and the balancing valve core (11) is provided in the valve sleeve (12); the valve body (6) and the valve sleeve (12) are respectively provided with a step surface and a shoulder, and the step surface and the shoulder cooperate to limit the movement of the valve sleeve (12) in the direction where the push rod (2) is located.

4. A flow control valve according to claim 3, characterized in that: The valve sleeve (12) is provided with a spacer sleeve (7) at one end away from the push rod (2), a ball pin (8) is provided in the spacer sleeve (7), and a plane section of the ball pin (8) contacts the end surface of the balance valve core (11).

5. A flow control valve according to claim 4, characterized in that: A nut (15) is provided on the side of the spacer (7) away from the push rod (2), two opposite spring seats (9) are provided inside the nut (15), and a spring is provided between the two spring seats (9).

6. A flow control valve according to claim 5, characterized in that: The end surfaces of the two spring seats (9) that are away from each other are both provided with concave arc surfaces.

7. A flow control valve according to claim 5, characterized in that: The spring comprises a small spring (14) and a large spring (10), and the large spring (10) is sleeved on the outer circumference of the small spring (14).

8. A flow control valve according to claim 5, characterized in that: An adjusting screw rod (16) is provided at one end of the nut (15) away from the valve sleeve (12).

9. A flow control valve according to claim 8, characterized in that: One of the concave arc surfaces of the two spring seats (9) is tangent to the spherical end of the ball pin (8), and the other concave arc surface is tangent to the spherical end of the adjusting screw (16).

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