A digital hydraulic servo control valve with closed-loop feedback

Abstract

The present invention discloses a digital hydraulic servo control valve with closed-loop feedback, including a valve body, a digital motor, a bushing, a valve core, a sensor and a transmission assembly, wherein the upper and lower parts of the valve body are provided with an inner cavity and an axial hole respectively; the valve core is movably arranged in the axial hole, the upper end of the valve core passes through the inner cavity and is connected to the sensor, and the lower end passes through the valve body; the bushing is threadedly connected to the valve core, the upper part of the bushing is located in the inner cavity, and the upper outer surface of the bushing is provided with a driving part; the digital motor is fixed to the side of the upper part of the valve body, and the transmission assembly is connected to the driving part and the digital motor respectively. The present invention adopts a motor to directly drive the bushing to rise and fall to realize the control of the valve, and adopts a valve core with a larger diameter as the feedback of the lead screw, which not only increases the torque of the motor, but also provides a position for the installation of the electrical feedback sensor, so that the valve has both mechanical feedback function and electrical feedback function, and can also realize manual drive, power-off protection, redundant drive and other extended functions.

Description

Technical Field

[0001] The invention relates to the technical field of servo valves, and in particular to a digital hydraulic servo control valve with closed-loop feedback. Background Art

[0002] The hydraulically controlled servo valve mainly refers to the electro-hydraulic servo valve, which outputs the modulated flow and pressure accordingly after receiving the electrical analog signal. It is both an electro-hydraulic conversion element and a power amplifier element, which can convert the weak electrical input signal of low power into high-power hydraulic energy (flow and pressure) output. In the electro-hydraulic servo system, it connects the electrical part with the hydraulic part to realize the conversion of electro-hydraulic signals and hydraulic amplification. It can be said that the electro-hydraulic servo valve is the core of the electro-hydraulic servo system control.

[0003] With the rapid development of valve technology, existing hydraulic servo valves usually have feedback functions. For example, the patent document with publication number CN207297964U discloses a mechanical feedback digital hydraulic cylinder with a valve sleeve that can follow the movement. The main shaft of the servo motor is connected to the screw, and the other end of the screw cooperates with the internal thread of the valve core. The valve core is embedded in the valve sleeve, and the screw drives the valve core to slide axially along the valve sleeve. The valve sleeve is embedded in the valve body. The outer wall of the valve core is provided with multiple bosses, and the inner wall of the valve sleeve is provided with a flow control window corresponding to the boss of the valve core. The valve core and the valve sleeve cooperate to form a three-position four-way hydraulic valve. The side wall of the valve body is radially provided with an oil passage hole corresponding to the three-position four-way hydraulic valve. The valve sleeve is provided with an internal thread near the cylinder end that cooperates with the external thread of the ball screw. The valve sleeve can slide axially along the valve body driven by the ball screw. This prior art can realize the dynamic feedback of the position of the hydraulic cylinder through the movement of the valve sleeve, thereby improving the controllability of the valve core. However, in practical applications, this prior art still has the following technical problems:

[0004] 1. The up and down movement of the bushing in this technology is driven by the rotation of the lead screw installed inside the piston rod of the hydraulic cylinder. However, due to the long stroke of the lead screw and the limited diameter, the output torque is small. The bushing has a small diameter, and the internal and external friction of the valve body and the valve core is large during use, which correspondingly leads to limited output flow, making this technology only suitable for occasions with small flow such as small hydraulic cylinders, short piston rod strokes, and slow piston rod speeds. On the contrary, if it is applied to occasions with large flow such as large hydraulic cylinders, long piston rod strokes, and fast piston rod speeds, it is easy to cause the lead screw to break.

[0005] 2. This technology only has mechanical feedback but not electrical feedback. When the external structure is limited and there is no installation position for the electrical feedback sensor, it cannot be used in situations where electrical feedback is required.

[0006] 3. In this technology, the valve core is only driven by a servo motor, but due to its structural limitations, it is difficult to achieve extended functions such as manual drive, power-off protection, and redundant drive. Summary of the invention

[0007] The purpose of the present invention is to overcome the above-mentioned technical problems existing in the prior art, and to provide a digital hydraulic servo control valve with closed-loop feedback. The present invention uses a motor to directly drive the sleeve to lift and lower to achieve valve control, and uses a valve core that extends out of the valve body to connect to external feedback. Compared with the existing structure in which the motor directly drives the valve core and the sleeve is used as the feedback structure of the lead screw, the present invention increases the torque of the motor through the gear mechanism on the one hand, so that the valve can be used not only in occasions with smaller flow, but also in occasions with larger flow such as larger hydraulic cylinders, longer piston rod strokes, and faster piston rod movement speeds. At the same time, feedback only requires rotating the valve core, and the required torque is small, which is not easy to cause the lead screw to break. On the other hand, it provides a position for the installation of an electrical feedback sensor, so that the valve has both mechanical feedback and electrical feedback functions. On the other hand, it can also realize extended functions such as manual drive, power-off protection, and redundant drive.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] A digital hydraulic servo control valve with closed-loop feedback, characterized in that it includes a valve body, a digital motor, a bushing, a valve core, a sensor and a transmission assembly, the upper part of the valve body is provided with an inner cavity, and the lower part of the valve body is provided with an axial hole communicated with the inner cavity; the valve core is movably arranged in the axial hole through a bearing, the upper end of the valve core passes through the inner cavity and is connected to the sensor, and the lower end of the valve core passes through the valve body and is used to connect to a controlled object; the bushing is threadedly connected to the valve core, the upper part of the bushing is located in the inner cavity, and the upper outer surface of the bushing is provided with a driving part; the digital motor is fixed to the side surface of the upper part of the valve body, one end of the transmission assembly is connected to the driving part, and the other end extends out of the valve body and is connected to the digital motor, and the digital motor can drive the bushing to rise and fall on the valve core through the transmission assembly.

[0010] The driving part is a driving tooth, and the transmission assembly drives the bushing via the driving tooth.

[0011] The transmission assembly includes a first bevel gear and a second bevel gear, the second bevel gear is meshed with the driving part, one end of the first bevel gear is meshed with the first bevel gear, and the other end extends out of the valve body and is connected to the digital motor.

[0012] The number of the digital motor and the transmission assembly is at least one set.

[0013] A boss is integrally formed on the valve core, a flow control window corresponding to the boss is provided on the bushing, and an oil through hole corresponding to the flow control window is provided on the valve body. The valve core, bushing and valve body cooperate to form a three-position four-way valve or a three-position three-way valve.

[0014] An upper cover plate for blocking the inner cavity is fixed at the upper end of the valve body, and a lower cover plate for blocking the axial center hole is fixed at the lower end.

[0015] The upper cover plate and the lower cover plate are both provided with through holes for the valve core to pass through.

[0016] The advantages of adopting the present invention are:

[0017] 1. The key improvement of the digital hydraulic servo control valve described in the present invention is to fix the digital motor on the side of the valve body, and use the digital motor to directly drive the sleeve to lift and lower to achieve valve control, and use a valve core with a larger diameter to connect external feedback. Compared with the existing structure in which the motor directly drives the valve core and uses the sleeve as the feedback structure of the lead screw, the present invention can increase the torque of the digital motor through the transmission component, so that the valve can be used in occasions with a larger hydraulic cylinder and a longer piston rod stroke, and it is not easy to cause the lead screw to break. On the other hand, it provides a position for the installation of the electrical feedback sensor. Specifically, the sensor can be directly installed on the end face of the valve body to test the position of the valve core, so that the valve has both mechanical feedback function and electrical feedback function, which is conducive to application in different occasions. On the other hand, by increasing the number of digital motors and transmission components, it can also realize manual drive, power-off protection, redundant drive and other extended functions.

[0018] 2. The present invention adopts two bevel gears to cooperate with the driving teeth on the bushing, which has the advantages of increased torque, stable force transmission, simple structure and efficient control.

[0019] 3. The present invention can use two or more sets of digital motors and transmission components, which not only improves the expansion function of the valve, but also provides safety guarantee for the stable operation of the system using the valve.

[0020] 4. The present invention can form a three-position four-way valve or a three-position three-way valve by cooperating the valve core, the bushing and the valve body, which is convenient for use in different working conditions.

[0021] 5. The present invention blocks the inner cavity and the axial hole by the upper cover plate and the lower cover plate respectively, which is beneficial to the installation and subsequent maintenance of each component.

[0022] 6. The present invention is not only applicable to the control of hydraulic cylinders, but also to linear motion, rotational motion and other occasions controlled by hydraulic servo. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the present invention;

[0024] Figure 2 This is a schematic diagram of the present invention having a redundant function.

[0025] Marked in the figure: 1, sensor, 2, first bevel gear, 3, upper cover, 4, second bevel gear, 5, lower cover, 6, digital motor, 7, valve body, 8, bushing, 9, valve core. DETAILED DESCRIPTION

[0026] The present invention provides a digital hydraulic servo control valve with closed-loop feedback, which can be used in conjunction with controlled objects such as hydraulic cylinders and hydraulic motors. Figure 1 As shown, it includes a valve body 7, a digital motor 6, a bushing 8, a valve core 9, a sensor 1, a transmission assembly, an upper cover plate 3 and a lower cover plate 5. Among them,

[0027] An inner cavity is provided at the upper portion of the valve body 7 , and the inner cavity may be a circular structure or a square structure, and may be specifically opened downward from the end surface of the upper end of the valve body 7 .

[0028] A cylindrical axial center hole is provided at the lower part of the valve body 7, and the axial center hole is communicated with the inner cavity.

[0029] The upper cover plate 3 is fixed to the upper end of the valve body 7 and blocks the inner cavity, the lower cover plate 5 is fixed to the lower end of the valve body 7 and blocks the axial hole, and both the upper cover plate 3 and the lower cover plate 5 are provided with through holes for the valve core 9 to pass through.

[0030] The valve core 9 is movably arranged in the axial hole through the bearing. The upper end of the valve core 9 passes through the inner cavity and the upper cover plate 3 in sequence and is connected to the sensor 1. The sensor 1 can collect the rotation angle of the valve core 9, thereby providing an electrical feedback signal for the control system. The lower end of the valve core 9 passes through the lower cover plate 5 and extends out of the valve body 7 to be connected with the lead screw or other structure of the controlled object. The valve core 9 can only rotate in the valve body 7 and cannot move up and down.

[0031] The bushing 8 is threadedly connected to the valve core 9, the upper part of the bushing 8 is located in the inner cavity, and a driving part is provided on the upper outer surface of the bushing 8. Preferably, the driving part can be set as a driving tooth, that is, a tooth-shaped structure can be used as the driving part.

[0032] The digital motor 6 is fixed on the side of the upper part of the valve body 7, one end of the transmission assembly is connected to the driving part, and the other end extends out of the valve body 7 and is connected to the digital motor 6. The transmission assembly drives the bushing 8 through the driving teeth, and the digital motor 6 can drive the bushing 8 to rise and fall on the valve core 9 through the transmission assembly.

[0033] In addition, a boss is integrally formed on the valve core 9 of the present invention, a flow control window corresponding to the boss is provided on the bushing 8, and an oil path through hole corresponding to the flow control window is provided on the valve body 7. The valve core 9, the bushing 8 and the valve body 7 cooperate to form a three-position four-way valve (with an oil path through hole P\A\B\T) or a three-position three-way valve (with an oil path through hole P\A\T) of a rotary sliding valve structure. Figure 1The present invention shows a three-position four-way valve with oil passage holes P\A\B\T. In actual application, by changing the relative positions of the bushing 8 and the valve core 9, the pressure direction and flow rate of the oil passage holes can be changed, thereby controlling the movement direction, speed and position of the controlled object such as a hydraulic cylinder or a hydraulic motor.

[0034] It should be noted that the structure in which the valve core 9, the bushing 8 and the valve body 7 cooperate to form a three-position four-way valve or a three-position three-way valve is conventional technology and will not be described in detail here.

[0035] Preferably, the transmission assembly includes a first bevel gear 2 and a second bevel gear 4, the second bevel gear 4 is meshed with the driving part, one end of the first bevel gear 2 is meshed with the first bevel gear 2, and the other end extends out of the valve body 7 and is connected to the digital motor 6. The present invention uses the first bevel gear 2 and the second bevel gear 4 as the transmission assembly, which can not only increase the transmission torque of the digital motor 6, but also can set the digital motor 6 on the side of the valve body 7, thereby providing an installation position for the sensor 1. In actual use, the digital motor 6 can drive the bushing 8 to rotate on the valve core 9 through the first bevel gear 2 and the second bevel gear 4, open the flow control window between the bushing 8 and the valve core 9, and the oil passage A / B outputs pressure oil / return oil or return oil / pressure oil respectively to control the action of the controlled object. After the controlled object is in action, a mechanical closed-loop feedback connection is set to the valve core 9 to drive the valve core 9 to rotate, reduce the window between the bushing 8 and the valve core 9, and when the window between the bushing 8 and the valve core 9 is completely closed, the controlled object stops moving, and the position of the controlled object can be accurately controlled.

[0036] In addition, the present invention can collect the rotation angle of the valve core 9 through the sensor 1 to provide an electrical feedback signal for the control system. Specifically, the digital motor 6 is controlled to rotate in the opposite direction through electrical feedback, and the pressure direction and flow rate of the output oil are controlled by controlling the rotation speed of the motor and the time difference of opening / closing the window, thereby controlling the position, movement direction and speed of the controlled object.

[0037] Preferably, since the present invention adopts a specific side digital motor 6 to directly drive the lifting and lowering of the bushing 8 to realize the control of the valve, the number of digital motors 6 and transmission components can be at least one set as needed. For example, the number of digital motors 6 and transmission components can be set to two or three sets as needed, thereby realizing manual drive, power-off protection, redundant drive and other extended functions. Figure 2 The schematic diagram of using two sets of digital motors 6 and transmission components is shown. Based on the schematic diagram, it can be seen that the present invention can realize extended functions such as manual drive, power-off protection, redundant drive, etc., thereby ensuring more stable operation of the equipment.

[0038] The digital hydraulic servo control valve of the present invention can be directly installed with the controlled object during actual use, or can be connected through a pipeline. The installation method is not restricted, and the use is more convenient.

[0039] In summary, the present invention uses mechanisms such as gears and threads to effectively amplify the output torque of the digital motor 6, only one level of hydraulic amplification is required, and the flow rate is applicable to a wide range. In addition, the traditional servo valve requires electrical feedback, and the present invention can use both electrical feedback and mechanical closed-loop feedback, with high control accuracy, and can easily set protection functions, and can accurately maintain the position of the controlled object when the control power is lost.

[0040] The above description is only a specific implementation mode of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes; all disclosed features, or all methods or steps in the process, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A digital hydraulic servo control valve with closed-loop feedback, characterized in that: The invention comprises a valve body (7), a digital motor (6), a bushing (8), a valve core (9), a sensor (1) and a transmission assembly, wherein an inner cavity is provided at the upper part of the valve body (7), and an axial hole communicating with the inner cavity is provided at the lower part of the valve body (7); the valve core (9) is movably arranged in the axial hole through a bearing, the upper end of the valve core (9) passes through the inner cavity and is connected to the sensor (1), and the lower end of the valve core (9) passes through the valve body (7) and is used to connect to a controlled object; the bushing (8) is threadedly connected to the valve core (9), the upper part of the bushing (8) is located in the inner cavity, and a driving part is provided on the upper outer surface of the bushing (8); the digital motor (6) is fixed to the side surface of the upper part of the valve body (7), one end of the transmission assembly is connected to the driving part, and the other end extends out of the valve body (7) and is connected to the digital motor (6), and the digital motor (6) can drive the bushing (8) to rise and fall on the valve core (9) through the transmission assembly; The valve core (9) is integrally formed with a boss, the bushing (8) is provided with a flow control window corresponding to the boss, the valve body (7) is provided with an oil passage hole corresponding to the flow control window, and the valve core (9), the bushing (8) and the valve body (7) cooperate to form a three-position four-way valve or a three-position three-way valve; The digital motor (6) can drive the bushing (8) to rotate on the valve core (9) through the transmission component, thereby opening a flow control window between the bushing (8) and the valve core (9), and the oil passage holes A / B respectively output pressure oil / return oil or return oil / pressure oil to control the movement of the controlled object. After the controlled object moves, the controlled object is provided with a mechanical closed-loop feedback connection to the valve core (9), which drives the valve core (9) to rotate, thereby reducing the window between the bushing (8) and the valve core (9). When the window between the bushing (8) and the valve core (9) is completely closed, the controlled object stops moving.

2. A digital hydraulic servo control valve with closed-loop feedback according to claim 1, characterized in that: The driving part is a driving tooth, and the transmission assembly drives the bushing (8) via the driving tooth.

3. A digital hydraulic servo control valve with closed-loop feedback according to claim 2, characterized in that: The transmission assembly comprises a first bevel gear (2) and a second bevel gear (4), the second bevel gear (4) being meshed with the driving portion, one end of the first bevel gear (2) being meshed with the first bevel gear (2), and the other end extending out of the valve body (7) to be connected to the digital motor (6).

4. A digital hydraulic servo control valve with closed-loop feedback according to claim 1, characterized in that: The number of the digital motor (6) and the transmission assembly is at least one set.

5. A digital hydraulic servo control valve with closed-loop feedback according to claim 1, characterized in that: An upper cover plate (3) for sealing the inner cavity is fixed to the upper end of the valve body (7), and a lower cover plate (5) for sealing the axial center hole is fixed to the lower end.

6. A digital hydraulic servo control valve with closed-loop feedback according to claim 5, characterized in that: The upper cover plate (3) and the lower cover plate (5) are both provided with a through hole for the valve core (9) to pass through.

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