A single-acting electro-hydraulic proportional push rod and electro-hydraulic proportional multi-way valve

Abstract

The present invention provides a single-acting electro-hydraulic proportional push rod and a proportional multi-way valve, the electro-hydraulic proportional push rod comprises an electromagnetic valve and a power cylinder, the electromagnetic push rod pushes the valve core to move, so that the power cylinder is connected to the oil inlet circuit, and the feedback push rod is pushed to move, and at the same time, when the feedback push rod pushes the feedback rod to compress the first elastic element, when the elastic force of the first elastic element is greater than the thrust of the electromagnetic push rod, the first elastic element pushes the valve core to move in the opposite direction of the set direction, and finally maintains balance at a critical position where the oil inlet is about to be closed and the oil return port is about to be opened. The balance point is determined by the actual physical structure and is a fixed point, which ingeniously realizes the normalization of the proportional coefficient of the electromagnetic proportional valve. At the same time, through the position-force feedback mechanism, a functional relationship between the input control current and the push rod displacement is established, and the precise control of the position of the electro-hydraulic push rod can be achieved by adjusting the input current.

Description

Technical Field

[0001] The invention relates to the field of hydraulics, and in particular to an electro-hydraulic proportional push rod and an electro-hydraulic proportional multi-way valve. Background Art

[0002] With the continuous improvement of the level of intelligence, higher requirements are put forward for the precise control of the control automation of equipment and actuators. Proportional control is an important means of intelligent precise control. At present, the mature electric proportional control device outputs an electromagnetic push rod proportional to the input current. The thrust of the push rod is very limited due to the physical limitations of the electromagnetic thrust. The thrust action stroke is short, and the size will change with the displacement. After a certain stroke, the thrust drops sharply. The thrust of the mature electromagnetic proportional push rod currently used in hydraulic valve control is below 200N, and the effective action stroke is below 5mm. Therefore, the power level of the solenoid valve directly driven by electromagnetic force is relatively small. High power and high precision are the current development trend of transmission control, and the limitations of the output force and action stroke of the electric proportional push rod cannot meet the current needs of transmission control, so the electro-hydraulic proportional push rod with greater driving force and longer action stroke has appeared. To solve the above problems, the current electro-hydraulic proportional push rods all use proportional amplifiers to amplify the control signal into a proportional current and output it to the pilot-stage proportional pressure reducing valve. The pilot-stage proportional pressure reducing valve outputs a proportional pressure proportional to the input signal. The proportional pressure is multiplied by its effective area on the pilot piston, which is converted into an output force F' proportional to the input signal. i1 Under steady-state conditions, F′1 and the spring restoring force N x and other axial forces F acting on the actuator OA (such as fluid force, friction force) to reach a balance, that is

[0003] F′ i1 =N x +F OA =k3x+F OA (1)

[0004] The solution is:

[0005]

[0006] Where, x is the displacement of the push rod, and k3 is the stiffness coefficient of the push rod return spring.

[0007] From formula (2), we can see that the displacement x is affected by three factors: the proportional output force F′ i1 , other axial forces F OA And the stiffness coefficient k3 of the return spring.

[0008] At present, the proportional current output control can be accurately realized through the current closed loop of the amplifier. Even so, the proportional pressure reducing valve still has hysteresis and repeatability error of the output pressure. Therefore, the output force F′ of the pilot-stage proportional pressure reducing valve i1 There are also hysteresis and repeatability errors, which become one of the main control errors of the proportional multi-way valve.

[0009] The existing spring manufacturing process level can also achieve the stabilization of k3 of the return spring within the rated temperature variation range and service life (that is, the impact of k3 changes in meeting engineering application requirements can be ignored).

[0010] The other axial force F OA The proportion is not large, but it cannot be ignored, and it will increase with the increase of flow and pressure through the main valve core (actuator). It is also one of the main errors of flow control in existing proportional flow valves (including proportional multi-way valves).

[0011] In order to obtain high speed load stiffness, existing proportional valves usually use constant pressure difference throttling speed regulation. Since the pressure difference is a constant value, the speed depends entirely on the opening of the valve port, that is, the displacement x of the valve core. Therefore, the accurate control of the valve core displacement has become the key to the precision speed control of the proportional flow valve. Due to the limitations of its control principle (refer to Formula 2), it is difficult to achieve precise position control for existing electro-hydraulic proportional valves. In order to solve this problem and achieve high-precision speed control, it is necessary to add a displacement sensor to collect the displacement of the valve core and feed it back to the control system to achieve closed-loop feedback of the valve core displacement. This also makes the structure and control of the valve more complicated, and the cost is greatly increased. Summary of the invention

[0012] In view of the defects in the prior art, the purpose of the present invention is to provide a single-acting electro-hydraulic proportional push rod, which includes a solenoid valve and a power cylinder, characterized in that the solenoid valve includes a solenoid push rod, a valve sleeve, a valve core, a first elastic element and a feedback rod; the power cylinder includes a feedback push rod, a piston and a second elastic element, the feedback push rod is connected to the piston, the piston divides the power cylinder into a power chamber and a spring chamber, one end of the second elastic element is connected to the piston, and the other end is connected to the end of the power cylinder, and the second elastic element controls the feedback push rod to reset; the solenoid push rod is connected to the valve core; the valve core and the feedback rod are connected through the first elastic element; the feedback rod abuts against the conical surface of the feedback push rod; when the control current is input to the solenoid valve, the solenoid push rod pushes the valve core to move in the set direction, the feedback push rod is moved by the hydraulic pressure, and at the same time, the conical surface of the feedback push rod pushes the valve core to move in the opposite direction of the set direction, and finally maintains balance at the critical position where the oil inlet is about to close and the oil return port is about to open.

[0013] Preferably, the valve sleeve is provided with an oil inlet and an oil return port in sequence from top to bottom, the oil inlet is connected to the oil inlet oil circuit, and the oil return port is connected to the oil return oil circuit.

[0014] Preferably, the valve sleeve is provided with an oil outlet connected to the power chamber of the power cylinder.

[0015] Preferably, the feedback rod is provided with an oil outlet and a cavity connected to the power chamber of the power cylinder.

[0016] Preferably, the valve core is provided with a through hole and a cavity, and the oil inlet and the oil return port can be opened and closed when the valve core moves.

[0017] Preferably, when the solenoid valve controls the solenoid push rod to push the valve core to move in the direction of closing the oil return port and opening the oil inlet, the power chamber is connected to the oil inlet oil circuit, pushing the feedback push rod to move; at this time, the conical surface of the feedback push rod pushes the feedback rod to move in the direction of closing the oil inlet and opening the oil return port, compressing the first elastic element, generating a reaction force to push the valve core to move in the direction of closing the oil inlet and opening the oil return port, so that the valve core maintains balance at the critical position where the oil inlet is about to close and the oil return port is about to open under the joint action of the solenoid push rod and the feedback push rod.

[0018] Preferably, the spring chamber is provided with a communication port, and the communication port is connected to the oil return circuit or the atmosphere.

[0019] Preferably, the power cylinder further comprises an actuator push rod, one end of which is connected to the piston, and the other end of which extends out of the power cylinder and is connected to the actuator mechanism.

[0020] At the same time, the present invention also provides an electro-hydraulic proportional multi-way valve, including a main valve and the above-mentioned single-acting electro-hydraulic proportional push rod, the main valve includes multiple loop control modules, and one or more of the multiple loop control modules use the single-acting electro-hydraulic proportional push rod as a pilot control.

[0021] The present invention inputs a proportional control current to the electromagnetic push rod to push the valve core to move in the direction of closing the return oil opening and opening the oil inlet opening, so that the power cylinder and the power chamber are connected to the oil inlet circuit, pushing the feedback push rod to move. At the same time, when the feedback push rod pushes the feedback rod to compress the first elastic element, when the elastic force of the first elastic element is greater than the thrust of the electromagnetic push rod, the first elastic element pushes the valve core to move in the direction of closing the oil inlet and opening the return oil opening, and finally maintains balance at a critical position where the oil inlet is about to be closed and the return oil opening is about to be opened. The balance point is determined by the actual physical structure and is a fixed point, which cleverly realizes the constantization of the proportional coefficient of the electromagnetic proportional valve (because the thrust of the electromagnetic push rod changes with the displacement of the push rod, although this change can be reduced by improving the structural design of the push rod, it cannot be eliminated. The present invention cleverly solidifies the balance point of the electromagnetic thrust through the physical structure, eliminating the change of the electromagnetic thrust with the displacement of the push rod). At the same time, through a direct position-force feedback mechanism, a functional relationship between the input control current and the push rod displacement (such as a typical linear functional relationship) is established, and the precise control of the position of the electro-hydraulic push rod can be achieved by adjusting the input current. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of a single-acting proportional push rod in the prior art;

[0023] Figure 2 It is a schematic diagram of the single-acting electro-hydraulic proportional push rod of the present invention;

[0024] Figure 4 It is a structural schematic diagram of a single-acting electro-hydraulic proportional push rod of the present invention;

[0025] Figure 3 It is a schematic diagram of a single-acting electro-hydraulic proportional push rod in another embodiment of the present invention;

[0026] Figure 5 It is a structural schematic diagram of a single-acting electro-hydraulic proportional push rod in another embodiment of the present invention;

[0027] Figure 6 This is a schematic diagram of the electro-hydraulic proportional multi-way valve of the present invention. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0029] Embodiment 1:

[0030] Reference Figure 2 , Figure 3The electro-hydraulic proportional push rod includes a solenoid valve 1 and a power cylinder 2. The solenoid valve 1 includes a solenoid push rod 11, a valve sleeve 12 and a valve core 13; the valve core 13 includes a valve core 131, a feedback spring 132 and a feedback rod 133; the power cylinder includes a feedback push rod 21, a piston 22, a return spring 23 and an execution push rod 24. The lower end of the solenoid push rod 11 is connected to the upper end of the valve core 133, one end of the feedback spring 132 is connected to the lower end of the valve core 131, and the other end is connected to the upper end of the feedback rod 133, and the lower end of the feedback rod abuts against the conical surface of the feedback push rod 21. The power cylinder 2 is divided into a power chamber A and a spring chamber B by the piston 22, the feedback push rod 21 is connected to the piston 22, one end of the return spring 23 is connected to the piston 22, and the other end is connected to the end of the power cylinder, one end of the execution push rod is connected to the piston, and the other end extends out of the power cylinder to connect with the actuator. The valve sleeve 12 is provided with an oil inlet, an oil return port and an oil outlet. The oil inlet is connected to the oil inlet oil passage P, and the oil return port is connected to the oil return oil passage T. The valve core 131 is provided with a through hole and a cavity. When oil is inlet, the pressure oil can flow into the valve core cavity through the P port and the oil inlet, and then flow into the power cavity A through the feedback spring cavity and the oil outlet. When oil is returned, the pressure oil returns to the oil tank from the A cavity through the oil outlet, the feedback spring cavity, the oil return port and the T port. At the same time, a connecting port is provided in the spring cavity B to connect to the atmosphere.

[0031] When the electric control signal input to the solenoid valve is 0, the reset spring keeps the actuator cylinder in place. When the solenoid valve inputs a proportional current I1, the solenoid push rod 11 generates a proportional thrust F i1 , pushing the valve core 13 downward, PA is connected, AT is disconnected, and the pressure oil flowing in from the P port enters the A chamber, pushing the feedback push rod 21 to move to the right. At the same time, the tapered part at the tail of the feedback push rod 21 pushes the feedback rod 133 upward, compressing the feedback spring 132, generating a reaction force F1, pushing the valve core 131 upward (or an upward movement trend). The further the feedback push rod moves to the right, the greater the distance the tapered part at the tail of the feedback push rod 21 pushes the feedback rod 133 upward, the greater the compression of the feedback spring 132, the greater the reaction force F1, the greater the upward movement of the valve core 131, and the opening of PA gradually closes. Finally, with the electromagnetic thrust F i1 Reach a balance, and the position of this balance point is the critical point where the valve core PA is about to close and AT is about to open.

[0032] F1=K1xtan(α) (3)

[0033] F i1 =K2I1 (4)

[0034] F1=F i1 (5)

[0035] From the above three formulas, we can get

[0036]

[0037] Where: x is the displacement of the feedback push rod, I1 is the proportional input current; α is the angle between the inclined surface of the cone and the horizontal; K1 is the stiffness coefficient of the feedback spring; K2 is the thrust coefficient of the electromagnetic push rod.

[0038] It can be seen from formula (6) that since K1 and α are both constants, as long as K2 is also a constant, the displacement of the electro-hydraulic proportional push rod is proportional to the input current. Usually K2 changes with the displacement of the electromagnetic push rod, and K2 is a constant at the same position. In the electro-hydraulic push rod mechanism provided by the present invention, the balance point of the electromagnetic push rod is fixed (the critical point at which the valve core PA is about to close), which cleverly achieves the constant state of K2. Since the thrust of the electromagnetic push rod changes with the displacement of the push rod, although this change can be reduced by improving the structural design of the push rod, it cannot be eliminated. The present invention cleverly solidifies the balance point of the electromagnetic thrust through the physical structure, eliminating the change of the electromagnetic thrust with the displacement of the push rod. For a single-acting electro-hydraulic proportional push rod, precise control of the position of the electro-hydraulic push rod can be achieved by adjusting the input current.

[0039] When the electromagnet loses power, the power chamber A and the spring chamber B on both sides of the feedback push rod 21 are connected to the T port (connecting the oil tank), and the piston 22 is subjected to the rebound force of the return spring 23 to reset the feedback push rod.

[0040] Example 2

[0041] Reference Figure 4 , Figure 5 This embodiment is an improvement on the embodiment 1, and the arrangement of the oil outlet and the connecting port is changed. The feedback rod 133 is provided with an oil outlet and a cavity, and a connecting port is provided in the spring cavity B to connect to the oil return passage T.

[0042] Embodiment 3: This embodiment is an improvement on Embodiment 1, in which the arrangement of the oil outlet is changed, and an oil outlet and a cavity are provided on the feedback rod 133 .

[0043] Embodiment 4: This embodiment is an improvement on Embodiment 1, and changes the arrangement of the connecting port. A connecting port is arranged in the spring chamber B to connect to the oil return passage T.

[0044] like Figure 6 As shown, the electro-hydraulic proportional multi-way valve includes a main valve and a single-acting electro-hydraulic proportional push rod. The main valve includes a head and tail block and multiple loop control modules. The multiple loop control modules have N single-acting electro-hydraulic proportional push rods for pilot control.

[0045] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0046] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0047] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] The above contents are further detailed descriptions of the present invention in combination with specific implementation methods, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention.

Claims

1. A single-acting electro-hydraulic proportional push rod, comprising a solenoid valve and a power cylinder, characterized in that: The solenoid valve comprises a solenoid push rod, a valve sleeve, a valve core, a first elastic element and a feedback rod; The power cylinder comprises a feedback push rod, a piston and a second elastic element, wherein the feedback push rod is connected to the piston, and the piston divides the power cylinder into a power chamber and a spring chamber, one end of the second elastic element is connected to the piston, and the other end is connected to the end of the power cylinder, and the second elastic element controls the feedback push rod to reset; The electromagnetic push rod is connected to the valve core; the valve core and the feedback rod are connected via a first elastic element; the feedback rod abuts against a conical surface of the feedback push rod; When a control current is input to the solenoid valve, the solenoid push rod pushes the valve core to move in the set direction, and the feedback push rod is moved by the hydraulic pressure. At the same time, the conical surface of the feedback push rod pushes the valve core to move in the opposite direction of the set direction, and finally maintains balance at the critical position where the oil inlet is about to close and the oil return port is about to open.

2. The single-acting electro-hydraulic proportional push rod according to claim 1, characterized in that: The valve sleeve is provided with an oil inlet and an oil return port in sequence from top to bottom. The oil inlet is connected to the oil inlet oil circuit, and the oil return port is connected to the oil return oil circuit.

3. The single-acting electro-hydraulic proportional push rod according to claim 2, characterized in that: The valve sleeve is provided with an oil outlet connected with the power chamber of the power cylinder.

4. The single-acting electro-hydraulic proportional push rod according to claim 2, characterized in that: The feedback rod is provided with an oil outlet and a cavity connected to the power cavity of the power cylinder.

5. The single-acting electro-hydraulic proportional push rod according to claim 3 or 4, characterized in that: The valve core is provided with a through hole and a cavity, and the oil inlet and the oil return port are opened and closed when the valve core moves.

6. The single-acting electro-hydraulic proportional push rod according to claim 5, characterized in that: When the solenoid valve When the electromagnetic push rod is controlled to push the valve core to move in the direction of closing the return oil port and opening the oil inlet, the power chamber is connected to the oil inlet oil circuit, pushing the feedback push rod to move; at this time, the conical surface of the feedback push rod pushes the feedback rod to move in the direction of closing the oil inlet and opening the return oil port, compressing the first elastic element, generating a reaction force to push the valve core to move in the direction of closing the oil inlet and opening the return oil port, so that the valve core maintains balance at the critical position where the oil inlet is about to close and the oil return port is about to open under the joint action of the electromagnetic push rod and the feedback push rod.

7. The single-acting electro-hydraulic proportional push rod according to claim 6, characterized in that: The spring chamber is provided with a communication port, and the communication port is communicated with the oil return circuit or the atmosphere.

8. The single-acting electro-hydraulic proportional push rod according to claim 7, characterized in that: The power cylinder also includes an actuator push rod, one end of which is connected to the piston, and the other end of which extends out of the power cylinder and is connected to the actuator.

9. An electro-hydraulic proportional multi-way valve, comprising a main valve and a single-acting electro-hydraulic proportional push rod as described in any one of claims 1 to 8, wherein the main valve comprises a plurality of loop control modules, and one or more of the plurality of loop control modules adopts the single-acting electro-hydraulic proportional push rod as a pilot control.

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