Control method for fluid valve, valve device and fluid valve

Abstract

A control method for a fluid valve, the fluid valve comprising a driving mechanism and a valve core, the driving mechanism having a zero-point position that corresponds to a closed position of the valve core. The control method comprises the following steps: acquiring a current position of the driving mechanism at which the valve core is in an open position, the current position being deflected from the zero¬ point position by a deflection distance D; the driving mechanism moving towards the zero-point position from the current position by a movement distance R to reach an over-travel position, wherein R = D + X, X being an over-travel distance; determining a reverse movement distance Y, wherein the reverse movement distance Y is less than the over-travel distance X; and the driving mechanism moving towards the zero-point position from the over-travel position by the reverse movement distance Y. The present disclosure also relates to a valve device comprising a control device configured to perform the control method, and a fluid valve comprising such a valve device.

Description

[0001] Description

[0002] Control method for fluid valve, valve device and fluid valve

[0003] Technical Field

[0004] The present disclosure relates to a control method for a fluid valve. In particular, the control method comprises a reverse movement step in which a driving mechanism of the fluid valve is controlled to move in a reverse direction by a reverse movement distance from an over-travel position located beyond a zero-point position. The present disclosure also relates to a valve device, and a fluid valve comprising such a valve device.

[0005] Background Art

[0006] A fluid valve generally comprises a valve core and a driving mechanism for driving the valve core. When the fluid valve closes, the driving mechanism controls the valve core to move to a closed position of contact with a sealing face defined by a valve component such as a valve seat, thus cutting off fluid communication. To avoid leakage, the driving mechanism will generally continue to move by a certain distance to an over-travel position, so that the valve core is in tight contact with the sealing face, ensuring the effectiveness of fluid valve closure. However, such over-travel will result in transmission components (such as gears) within the driving mechanism being in a stressed state for a long period of time, and thus being likely to suffer premature material fatigue; consequently, the service life of these transmission components, or even the fluid valve as a whole, is shortened.

[0007] Summary of the Invention

[0008] Thus, the present disclosure is intended to solve the abovementioned problem, an objective thereof being to provide a control method for a fluid valve that comprises a reverse movement step. In the reverse movement step, a driving mechanism of the fluid valve moves in a reverse direction by a reverse movement distance from an over-travel position, thereby reducing or eliminating stress sustained by transmission components in the driving mechanism, to increase the service life of the transmission components and the fluid valve.

[0009] The abovementioned objective is achieved by a control method for a fluid valve according to an embodiment of the present disclosure, the fluid valve comprising a driving mechanism and a valve core, the driving mechanism having a zero-point position that corresponds to a closed position of the valve core. The control method comprises the following steps: acquiring a current position of the driving mechanism at which the valve core is in an open position, the current position being deflected from the zero-point position by a deflection distance D; the driving mechanism moving towards the zero-point position from the current position by a movement distance R to reach an over-travel position, wherein R = D + X, X being an over-travel distance; determining a reverse movement distance Y, wherein the reverse movement distance Y is less than the over-travel distance X; the driving mechanism moving towards the zero-point position from the overtravel position by the reverse movement distance Y.

[0010] One objective of the present disclosure is to provide a control method for a fluid valve which reduces or eliminates stress sustained by transmission components in the driving mechanism, to increase the service life of the transmission components and the fluid valve. By means of the control method according to the present disclosure, the driving mechanism of the fluid valve first moves to an over-travel position from a current position at which the valve core is open. Since the over-travel position lies beyond the zero-point position (at which the valve core is closed) by the over-travel distance X, the valve core can tightly press against a sealing face of the fluid valve, ensuring the effectiveness of fluid valve closure. The control method according to the present disclosure can then determine a reverse movement distance Y less than the over-travel distance X, and control the driving mechanism to move from the over-travel position by the reverse movement distance Y. By means of this reverse movement step, the control method according to the present disclosure reduces or eliminates stress sustained by transmission components in the driving mechanism, and can thus increase the service life of the transmission components and the fluid valve. In addition, since the reverse movement distance Y is less than the over-travel distance X, the valve core of the fluid valve can still tightly press against the sealing face, thus avoiding leakage.

[0011] The control method for a fluid valve according to the present disclosure may further have one or more of the following features individually or in combination.

[0012] According to an optional embodiment of the present disclosure, determining the reverse movement distance Y comprises calculating the reverse movement distance Y according to the following formula: Y = Yo(l + K), where Yo is an initial reverse movement distance of the fluid valve, and K is an adjustment factor K which varies according to an operating time of the fluid valve. In the course of fluid valve operation, the transmission components of the driving mechanism will experience wear, with a drop in mechanical performance, so a greater reverse movement distance is needed to eliminate stress on the transmission components. By adding the adjustment factor when calculating the reverse movement distance, the control method of the present disclosure can dynamically compensate the reverse movement distance according to the operating time of the fluid valve, so that stress on the transmission components can be eliminated even when the transmission components experience wear.

[0013] According to an optional embodiment of the present disclosure, the control method further comprises: when the fluid valve is energized, acquiring a total movement distance T of the driving mechanism; and determining the reverse movement distance Y comprises: determining an adjustment factor K corresponding to the total movement distance T by querying a predetermined table. In the course of fluid valve operation, the wear experienced by the transmission components of the driving mechanism is positively correlated to the total movement distance T of the driving mechanism; i.e. the greater the total movement distance T, the greater the wear experienced by the transmission components. Therefore, the total movement distance T of the driving mechanism can be used to characterize the wear experienced by the transmission components, and in turn used to determine the adjustment factor K.

[0014] According to an optional embodiment of the present disclosure, the control method further comprises: when the fluid valve operates, cumulatively recording a distance S moved on this occasion by the driving mechanism; and when the fluid valve is de-energized, updating the total movement distance T according to the distance S moved on this occasion. Thus, the control method according to the present disclosure is able to promptly change the adjustment factor K according to the updated total movement distance T, thereby dynamically compensating the reverse movement distance.

[0015] According to an optional embodiment of the present disclosure, the initial reverse movement distance Yo is determined when the fluid valve is manufactured, wherein the initial reverse movement distance Yo is determined to be a critical distance that causes the valve core to begin to move towards the open position from the closed position. Based on the above features, the control method according to the present disclosure can fully eliminate stress on transmission components and also avoid fluid valve leakage.

[0016] The present disclosure also relates to a valve device, comprising a driving mechanism, a valve core and a control device, the driving mechanism having a zero-point position that corresponds to a closed position of the valve core, characterized in that the control device is configured to perform the following steps: acquiring a current position of the driving mechanism at which the valve core is in an open position, the current position being deflected from the zero-point position by a deflection distance D; causing the driving mechanism to move towards the zero-point position from the current position by a movement distance R to reach an over-travel position, wherein R = D + X, X being an over-travel distance; determining a reverse movement distance Y, wherein the reverse movement distance Y is less than the over-travel distance X; causing the driving mechanism to move towards the zero-point position from the over-travel position by the reverse movement distance Y.

[0017] As stated above, since the driving mechanism moves towards the zero-point position from the over-travel position by the reverse movement distance Y, the valve device according to the present disclosure reduces or eliminates stress sustained by the transmission components in the driving mechanism, so can increase the service life of the transmission components and the fluid valve. In addition, since the reverse movement distance Y is determined to be less than the over-travel distance X, the valve core of the valve device can still tightly press against the sealing face, thus avoiding leakage.

[0018] The valve device according to the present disclosure may also have one or more of the following features individually or in combination.

[0019] According to an optional embodiment of the present disclosure, when determining the reverse movement distance Y, the control device calculates the reverse movement distance Y according to the following formula: Y = Yo(l + K); the Yo is an initial reverse movement distance of the valve device, and K is an adjustment factor K which varies according to an operating time of the valve device. As stated above, by adding the adjustment factor when calculating the reverse movement distance, the valve device of the present disclosure can dynamically compensate the reverse movement distance according to the operating time of the valve device, so that stress on the transmission components can be eliminated even when the transmission components experience wear.

[0020] According to an optional embodiment of the present disclosure, the control device is configured to perform the following step: when the valve device is energized, acquiring a total movement distance T of the driving mechanism; wherein, when determining the reverse movement distance Y, the control device determines an adjustment factor K corresponding to the total movement distance T by querying a predetermined table. Thus, the effect of wear experienced by the transmission components can be taken into account when determining the adjustment factor K.

[0021] According to an optional embodiment of the present disclosure, when the valve device operates, the control device also cumulatively records a distance S moved on this occasion by the driving mechanism; when the valve device is deenergized, the control device updates the total movement distance T according to the distance S moved on this occasion. Thus, the valve device according to the present disclosure is able to promptly change the adjustment factor K according to the updated total movement distance T, thereby dynamically compensating the reverse movement distance.

[0022] According to an optional embodiment of the present disclosure, the initial reverse movement distance Yo is determined when the valve device is manufactured, wherein the initial reverse movement distance Yo is determined to be a critical distance that causes the valve core to begin to move towards the open position from the closed position. Based on the above features, the valve device according to the present disclosure can fully eliminate stress on transmission components and also avoid fluid valve leakage.

[0023] According to an optional embodiment of the present disclosure, the control device comprises a microprocessor and a memory, the memory being readable / writable by the microprocessor, wherein the total movement distance T, the initial reverse movement distance Yo and / or the predetermined table are stored in the memory.

[0024] According to an optional embodiment of the present disclosure, the driving mechanism comprises a stepper motor and a gear transmission mechanism, wherein the stepper motor drives the valve core via the gear transmission mechanism.

[0025] According to an optional embodiment of the present disclosure, the gear transmission mechanism has a transmission ratio greater than 100.

[0026] According to an optional embodiment of the present disclosure, the driving mechanism comprises a stepper motor; the stepper motor comprises a rotor; the over-travel distance X corresponds to a first number of steps of rotation of the rotor in a first direction; the reverse movement distance Y corresponds to a second number of steps of rotation of the rotor in a second direction; and the second number of steps is less than the first number of steps.

[0027] The present disclosure also relates to a fluid valve, comprising the valve device described above.

[0028] Brief Description of the Drawings

[0029] The foregoing and other features and advantages of the present disclosure will become more apparent from the following detailed description of exemplary embodiments with reference to the accompanying drawings, and the description and the accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. The drawings below are not scaled drawings according to actual dimensions but rather focus on showing the main purpose of the present disclosure. In the figures: Fig. 1 shows a schematic diagram of a control approach for a fluid valve according to the present disclosure.

[0030] Fig. 2 shows a flow chart of a control method for realizing the control approach shown in Fig. 1.

[0031] Fig. 3A schematically shows a gear transmission mechanism before a driving mechanism has moved in a reverse direction.

[0032] Fig. 3B schematically shows the gear transmission mechanism after the driving mechanism has moved in the reverse direction.

[0033] Detailed Description of the Invention

[0034] To clarify the objective, technical solutions and advantages of embodiments of the present disclosure, the technical solutions of the embodiments of the present disclosure are described clearly and completely below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are some rather than all of the embodiments of the present disclosure.

[0035] Unless defined otherwise, the technical or scientific terms used herein shall have the common meanings as understood by those of ordinary skill in the field to which the present disclosure belongs. Words such as "one", "a" or "the" used in the description and the claims of the patent application disclosed herein do not indicate a quantity limit, but mean that there is at least one. Words such as "comprise" or "include" mean that the element or object appearing before the word encompasses the elements or objects and their equivalents listed after the word, without excluding other elements or objects. Words such as "first" and "second" used in the description and claims of the patent application disclosed herein do not denote any order, quantity or importance, and are merely used to distinguish different component parts. The terms “upper”, “lower”, “left”, “right” and the like are only used to indicate a relative positional relationship, and when the absolute position of a described object changes, the relative positional relationship may also change accordingly.

[0036] Fig. 1 shows a schematic diagram of a control approach for a fluid valve according to the present disclosure; Fig. 2 shows a flow chart of a control method that realizes the control approach shown in Fig. 1. In a non-limiting embodiment, the fluid valve has a valve device that comprises a driving mechanism, a valve core and a control device. The driving mechanism further comprises a stepper motor and a gear transmission mechanism, wherein the stepper motor drives the valve core via the gear transmission mechanism. The gear transmission mechanism may be multiple stages of speed-changing gears, with a transmission ratio greater than 100. The control device may comprise a microprocessor (MCU) and a memory which the microprocessor can read from and write to. The memory may be an EEPROM chip outside the microprocessor, or a data storage unit built into the microprocessor itself.

[0037] The control approach shown in Fig. 1 involves switching of the fluid valve from an open state to a closed state; the figure specifically shows a schematic diagram of positions passed through by the driving mechanism as the fluid valve switches from the open state to the closed state. As shown in the figure, the driving mechanism has a zero-point position and a fully-open position, and the distance of travel by which the driving mechanism needs to move from the zero-point position to the fully-open position is Z. When the driving mechanism is at the zero-point position, the valve core is at a closed position of contact with a sealing face (provided on a valve seat for example) of the fluid valve, blocking the flow of fluid, such that the fluid valve is in a closed state in which fluid is not permitted to flow through. When the driving mechanism is at the fully-open position, the valve core is at a position which permits fluid to flow through at a maximum flow rate, and the fluid valve is in a fully-open state. In addition to including the abovementioned fully-open state, open states of the fluid valve may also include intermediate states in which fluid is permitted to flow through at selected flow rates less than the maximum flow rate, the driving mechanism correspondingly being at intermediate positions between the zero-point position and the fully-open position.

[0038] When the fluid valve is closed from an open state, the driving mechanism moves to the zero-point position from the fully-open position or an intermediate position, and drives the valve core to move (e.g. rotate) from an open position to a closed position of contact with the sealing face of the fluid valve, to block the flow of fluid. To avoid leakage from the fluid valve, the driving mechanism continues to move from the zero-point position by an over-travel distance X to an over-travel position. As shown in Fig. 1, the over-travel position is located at the opposite side of the zero-point position from the fully-open position. As it moves from the zeropoint position to the over-travel position, the driving mechanism will drive the valve core to press against the sealing face, ensuring tight contact between the valve core and the sealing face, and thus achieving the effect of preventing fluid valve leakage.

[0039] As stated above, once the valve core has reached the closed position, the overtravel distance X by which the driving mechanism moves from the zero-point position to the over-travel position will not be converted proportionally to movement of the valve core, and instead will press the valve core against the sealing face. In fact, the over-travel distance X of the driving mechanism is partially absorbed by internal transmission components of the driving mechanism. Figs. 3A and 3B show two meshed gears of a gear transmission mechanism, which serve as transmission components of the driving mechanism. As shown in Fig. 3A, when the driving mechanism is at the over-travel position, teeth of the two meshed gears will abut each other, and compress each other. At the stress points of compression, the material of the gears is compressed and deforms, partially absorbing the over-travel distance X of the driving mechanism. In the case of gear transmission mechanisms with large transmission ratios (e.g. greater than 100, preferably greater than 200), the over-travel distance X that compressive deformation of the gears can absorb is quite significant.

[0040] However, if they are in a stressed state for a long time, the stress produced inside the transmission components will make the material thereof susceptible to fatigue, shortening their service life. For this reason, the valve device according to the present disclosure adds a reverse movement step to the process of closing the fluid valve. Specifically, once the driving mechanism has reached the over-travel position, the control device of the valve device determines a reverse movement distance Y, then causes the driving mechanism to move by the reverse movement distance Y from the over-travel position towards the zero-point position, thereby releasing the stress on the transmission components. Fig. 3B shows the two meshed gears of the gear transmission mechanism after the driving mechanism has moved in the reverse direction. After the reverse movement step, the teeth of the gears break contact with each other (as shown in Fig. 3B) or abut each other with a relatively small force (not shown), the compression force between the gears is weakened or eliminated, the material recovers from the deformed state, and the internal stress is released, thus extending the service life. Since the reverse movement distance Y of the driving mechanism is used to release stress from the transmission components, the valve core of the fluid valve remains at its closed position, and will not move towards the open position. Therefore, the reverse movement step of the driving mechanism will not cause leakage from the fluid valve. Preferably, the reverse movement distance Y may also be set less than the over-travel distance X, to ensure that the fluid valve will not leak.

[0041] A control method for a fluid valve is described below with reference to Figs. 1 and 2. The control method may be executed by the valve device of the fluid valve described above, and in particular is applied to a fluid valve in an open state, to switch it from an open state to a closed state. The control method comprises the following steps:

[0042] Firstly, a current position of the driving mechanism is acquired, the current position being deflected from the zero-point position by a deflection distance D. The acquisition is preferably performed by means of a sensor in communication with the microprocessor in the control device of the valve device. In the case of a fluid valve in an open state, the current position of the driving mechanism is between the zero-point position and the fully-open position, and may occupy the fully-open position. The deflection distance D of the current position may be represented by the number of steps of rotation needed for the rotor of the stepper motor to rotate from the zero-point position to the current position, or may be represented as a percentage of the travel Z from the zero-point position to the fully- open position. For example, if movement of the driving mechanism from the zeropoint position to the fully-open position requires 1000 steps of rotation of the stepper motor rotor, and movement from the zero-point position to the current position requires 600 steps of rotation of the stepper motor rotor, the value of the deflection distance D may be 600 steps or 60%.

[0043] The driving mechanism then moves towards the zero-point position from the current position by a movement distance R to reach an over-travel position, wherein R = D + X, X being the over-travel distance. When the driving mechanism moves by the deflection distance D from the current position, the valve core of the valve device contacts the sealing face of the fluid valve, and the fluid valve is thus closed. Further movement of the driving mechanism by the over-travel distance X can ensure that the valve core is completely closed, avoiding leakage from the fluid valve. Similarly, the movement distance R and the over-travel distance X may be represented by the number of steps of rotation of the stepper motor rotor, or as a percentage of the travel Z. For example, the value of the over-travel distance X may be 10 steps, 50 steps or 100 steps, etc., or may be 1%, 5% or 10%, etc.

[0044] A reverse movement distance Y is then determined, wherein the reverse movement distance Y is less than the over-travel distance X. The determination of the reverse movement distance Y is preferably performed by the control device of the valve device, specifically by the microprocessor in the control device. Similarly, the reverse movement distance Y may be represented by the number of steps of rotation of the stepper motor rotor, or as a percentage of the travel Z. For example, the value of the reverse movement distance Y may be 5 steps, 10 steps or 50 steps, etc., or may be 0.5%, 1% or 5%, etc. It should be noted that the over-travel distance X and the reverse movement distance Y correspond to opposite directions of rotation of the stepper motor rotor. For example, the over-travel distance X corresponds to a first number of steps of rotation of the rotor in a first direction; the reverse movement distance Y corresponds to a second number of steps of rotation of the rotor in a second direction; and the second number of steps is less than the first number of steps.

[0045] Finally, the driving mechanism moves towards the zero-point position from the over-travel position by the reverse movement distance Y. As stated above, such a reverse movement step can reduce or eliminate stress sustained by the transmission components, thus extending the service life of the transmission components and the fluid valve.

[0046] Although the reverse movement step described above extends the service life of the transmission components and the fluid valve, the transmission components will still unavoidably experience wear in the course of fluid valve operation, resulting in a drop in mechanical performance. As a result of this wear and drop in mechanical performance, the same reverse movement distance will be unable to eliminate stress on the transmission components. Therefore, the control method according to the present disclosure also compensates the reverse movement distance Y according to the operating time of the fluid valve.

[0047] Specifically, when determining the reverse movement distance Y, the reverse movement distance Y is calculated using the following formula (1):

[0048] Y = Yo(l + K), (1), where Yo is an initial reverse movement distance of the fluid valve, and K is an adjustment factor which varies according to the operating time of the fluid valve.

[0049] The initial reverse movement distance Yo is determined when the fluid valve is manufactured, and stored in the memory of the control device of the fluid valve. Specifically, in a testing step when the fluid valve is leaving the factory, the driving mechanism begins to move in the reverse direction from the over-travel position, and at the same time, observation is performed to determine whether the valve core has begun to rotate. The critical distance at which the valve core begins to move towards the open position from the closed position is determined to be the initial reverse movement distance Yo. Exemplary test results are as follows:

[0050] The driving mechanism moves 1 step in the reverse direction, the valve core does not move; the driving mechanism moves 2 steps in the reverse direction, the valve core does not move; the driving mechanism moves 3 steps in the reverse direction, the valve core does not move; the driving mechanism moves 4 steps in the reverse direction, the valve core does not move; the driving mechanism moves 5 steps in the reverse direction, the valve core does not move; the driving mechanism moves 6 steps in the reverse direction, the valve core moves; the driving mechanism moves 7 steps in the reverse direction, the valve core moves; the driving mechanism moves 8 steps in the reverse direction, the valve core moves.

[0051] According to the above test results, the value of the initial reverse movement distance Yo is 5 steps.

[0052] In a non-limiting embodiment, the operating time of the fluid valve is represented by a total movement distance T of the driving mechanism. The total movement distance T is stored in the memory in the control device of the fluid valve, and updated during operation of the fluid valve. Specifically, when the fluid valve operates, the control device of the fluid valve cumulatively records a distance S moved on this occasion by the driving mechanism, and updates the total movement distance T when the fluid valve is de-energized according to the distance S moved on this occasion. For example, when the fluid valve is energized and operates a single time, the movement of the driving mechanism is recorded as follows: 500 steps of movement from the zero-point position to the current position at which the valve core is open, 550 steps of movement towards the zero-point position from the current position to the over-travel position, and 40 steps of movement from the over-travel position in the reverse direction; the distance S moved on this occasion by the driving mechanism is then 500 + 550 + 40 = 1090 steps. When the fluid valve is de-energized, the control device of the fluid valve adds the distance S moved on this occasion (i.e. adds 1090 steps) to the total movement distance T, i.e. the total movement distance is updated to T + S, and written into the memory.

[0053] In a non-limiting embodiment, a predetermined table is also stored in the memory in the control device of the fluid valve; this table records a correspondence between the total movement distance T and the adjustment factor K. An exemplary predetermined table is as follows:

[0054] Referring to the table above, the reverse movement distance Y moved by the driving mechanism in the reverse movement step increases as the total movement distance T increases, and is thus able to compensate for wear of the transmission components.

[0055] Fig. 2 shows a flow chart of the control method described above. Referring to Table 2, when the fluid valve is energized, the microprocessor in the control device reads the total movement distance T of the fluid valve from the memory. Thereafter, the procedure of the control method can proceed to different procedural branches, including calculating the reverse movement distance Y, controlling the fluid valve to operate, and updating the total movement distance T. In the procedural branch in which the reverse movement distance Y is calculated, the control device further acquires the initial reverse movement distance Yo via the microprocessor, then queries the predetermined table stored in the memory according to the total movement distance T read, to obtain the adjustment factor K, and calculates the reverse movement distance Y using formula (1). This reverse movement distance Y will be used in the present energization cycle (i.e. the time period from fluid valve energization to fluid valve de-energization) of the fluid valve. In the procedural branch in which the fluid valve is controlled to operate, the control device may receive an external control command (e.g. a control command of a vehicle thermal management system) and control the driving mechanism of the fluid valve to move, driving the valve core to open or close the fluid valve. In particular, when closing the fluid valve, the driving mechanism moves from the current position to the zero-point position and continues moving to the over-travel position, then moves towards the zero-point position from the over-travel position by the previously confirmed reverse movement distance Y, thereby releasing stress on transmission components such as gears while avoiding fluid valve leakage, so as to extend life. In the procedural branch in which the total movement distance T is updated, the control device cumulatively records the distance S moved on this occasion after fluid valve energization by means of the microprocessor, and upon de-energization, writes the updated total movement distance T + S into the memory, for use in the next energization cycle.

[0056] Certain features, structures or characteristics in one or more embodiments of the present disclosure may be combined appropriately.

[0057] The above are merely demonstrative embodiments of the present disclosure, and are not intended to limit the protection scope of the present disclosure, which is determined by the appended claims. Those skilled in the art will understand that changes and improvements can be made to the various embodiments described herein, without departing from the scope of the present disclosure as defined in the appended claims. In addition, for clarity and conciseness, descriptions of familiar functions and structures may be omitted.

[0058] Finally, it should also be understood that certain technical features in the embodiments might not be necessary for solving a specific technical problem, so these technical features could be absent or omitted without affecting the solution of the technical problem or the formation of the technical solution; furthermore, features, elements and / or functions of one embodiment could be suitably combined, integrated or coordinated with features, elements and / or functions of one or more other embodiments, unless such combination, integration or coordination cannot be implemented.

Claims

Claims1. Control method for a fluid valve, the fluid valve comprising a driving mechanism and a valve core, the driving mechanism having a zero-point position that corresponds to a closed position of the valve core, characterized in that the control method comprises the following steps: acquiring a current position of the driving mechanism at which the valve core is in an open position, the current position being deflected from the zero-point position by a deflection distance D; the driving mechanism moving towards the zero-point position from the current position by a movement distance R to reach an over-travel position, wherein R = D + X, X being an over-travel distance; determining a reverse movement distance Y, wherein the reverse movement distance Y is less than the over-travel distance X; the driving mechanism moving towards the zero-point position from the overtravel position by the reverse movement distance Y2. Control method according to Claim 1, characterized in that determining the reverse movement distance Y comprises calculating the reverse movement distance Y according to the following formula:Y = YO(1 + K), where the Yo is an initial reverse movement distance of the fluid valve, and K is an adjustment factor K which varies according to an operating time of the fluid valve.

3. Control method according to Claim 2, further comprising: when the fluid valve is energized, acquiring a total movement distance T of the driving mechanism, characterized in that determining the reverse movement distance Y comprises: determining an adjustment factor K corresponding to the total movement distance T by querying a predetermined table.

4. Control method according to Claim 3, further comprising: when the fluid valve operates, cumulatively recording a distance S moved on this occasion by the driving mechanism, when the fluid valve is de-energized, updating the total movement distance Taccording to the distance S moved on this occasion.

5. Control method according to any one of Claims 2 - 4, characterized in that the initial reverse movement distance Yo is determined when the fluid valve is manufactured, wherein the initial reverse movement distance Yo is determined to be a critical distance that causes the valve core to begin to move towards the open position from the closed position.

6. Valve device, comprising a driving mechanism, a valve core and a control device, the driving mechanism having a zero-point position that corresponds to a closed position of the valve core, characterized in that the control device is configured to perform the following steps: acquiring a current position of the driving mechanism at which the valve core is in an open position, the current position being deflected from the zero-point position by a deflection distance D; causing the driving mechanism to move towards the zero-point position from the current position by a movement distance R to reach an over-travel position, wherein R = D + X, X being an over-travel distance; determining a reverse movement distance Y, wherein the reverse movement distance Y is less than the over-travel distance X; causing the driving mechanism to move towards the zero-point position from the over-travel position by the reverse movement distance Y.

7. Valve device according to Claim 6, characterized in that when determining the reverse movement distance Y, the control device calculates the reverse movement distance Y according to the following formula:Y = Yo(l + K), where the Yo is an initial reverse movement distance of the valve device, and K is an adjustment factor K which varies according to an operating time of the valve device.

8. Valve device according to Claim 7, characterized in that the control device is configured to perform the following step: when the valve device is energized, acquiring a total movement distance T of the driving mechanism; wherein, when determining the reverse movement distance Y, the controldevice determines an adjustment factor K corresponding to the total movement distance T by querying a predetermined table.

9. Valve device according to Claim 8, characterized in that when the valve device operates, the control device also cumulatively records a distance S moved on this occasion by the driving mechanism; when the valve device is de-energized, the control device updates the total movement distance T according to the distance S moved on this occasion.

10. Valve device according to any one of Claims 7 - 9, characterized in that the initial reverse movement distance Yo is determined when the valve device is manufactured, wherein the initial reverse movement distance Yo is determined to be a critical distance that causes the valve core to begin to move towards the open position from the closed position.

11. Valve device according to Claim 9, characterized in that the control device comprises a microprocessor and a memory, the memory being readable / writable by the microprocessor, wherein the total movement distance T, the initial reverse movement distance Yo and / or the predetermined table are stored in the memory.

12. Valve device according to any one of Claims 6 - 9, characterized in that the driving mechanism comprises a stepper motor and a gear transmission mechanism, wherein the stepper motor drives the valve core via the gear transmission mechanism.

13. Valve device according to Claim 12, characterized in that the gear transmission mechanism has a transmission ratio greater than 100.

14. Valve device according to Claim 6, characterized in that the driving mechanism comprises a stepper motor; the stepper motor comprises a rotor; the over-travel distance X corresponds to a first number of steps of rotation of the rotor in a first direction; the reverse movement distance Y corresponds to a second number of steps of rotation of the rotor in a second direction; and the second number of steps is less than the first number of steps.

15. Fluid valve, characterized in that the fluid valve comprises the valve device according to any one of Claims 6 - 14.

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