Thermostatic valve and control method thereof

Abstract

The present invention discloses a thermostatic valve, including a valve body and a valve core, wherein the valve body is provided with a cold water inlet, a hot water inlet and a warm water outlet, the valve core is arranged inside the valve body, the valve body is provided with a driving member connected to the valve core in a transmission manner, the driving member is driven by a stepping motor to drive the valve core to move, the warm water outlet is provided with a temperature sensor, the stepping motor and the temperature sensor are connected to a temperature control component; and a thermostatic valve control method. The present invention can realize accurate and rapid control of the outlet water temperature of the thermostatic valve, and greatly reduce or even eliminate the cumbersome calibration process of the thermostatic valve before leaving the factory.

Description

Technical Field

[0001] The present invention relates to the field of valves, and more particularly to a thermostatic valve and a control method thereof. Background Art

[0002] The existing thermostatic valve uses a knob to set the outlet water temperature. By turning the knob in or out, the position of the thermostatic valve core of the thermostatic bulb changes to change the flow ratio of cold and hot water and thus change the outlet water temperature. When the pressure of cold and hot water is unbalanced and difficult to adjust and the outlet water temperature changes, the thermostatic bulb of the thermostatic valve core of the thermostatic bulb will expand or contract with the change of the outlet water temperature to push the piston to control the inlet flow ratio of cold and hot water so that the outlet water temperature is always maintained at the set temperature. Since the tolerances of the manufacturing, assembly, spring, and temperature characteristics of the thermostatic valve core of the thermostatic bulb will cause great differences in the functions of the finished product, strict calibration is required before leaving the factory.

[0003] "Calibration" means adjusting the compression of the spring through the knob to provide the appropriate initial force. Different initial forces correspond to different outlet water temperatures after the cold and hot water mixing ratios. Due to the tolerance of each component, even after calibration, it is impossible to consistently obtain the same outlet water temperature for different products at the same knob position. This also means that it is impossible to provide a consistent and accurate temperature scale for users to accurately set the required outlet water temperature. Therefore, when using the knob to adjust the set temperature, you only get a relatively high or low temperature, and you cannot clearly know the temperature value. Summary of the invention

[0004] An object of the present invention is to provide a thermostatic valve and a control method thereof, which can achieve accurate and rapid control of the outlet water temperature and greatly reduce or even eliminate the cumbersome calibration process of the thermostatic valve before leaving the factory.

[0005] In order to achieve the purpose and other advantages according to the present invention, a thermostatic valve is provided, including a valve body and a valve core, the valve body is provided with a cold water inlet, a hot water inlet and a warm water outlet, the valve core is arranged inside the valve body, and is characterized in that the valve body is provided with a driving member transmission-connected to the valve core, the driving member is driven by a stepper motor to drive the valve core to move, a temperature sensor is provided on the warm water outlet, and the stepper motor and the temperature sensor are connected to a temperature control component.

[0006] Preferably, in the thermostatic valve, a driving member interface is provided on the valve body, the driving member interface is perpendicular to the axis of the valve body, the driving member is rod-shaped and inserted in the driving member interface, the side wall of the driving member is threadedly connected to the inner wall of the driving member interface, the stepper motor is arranged at an end of the driving member interface away from the valve body, the output end of the stepper motor is coaxially arranged with the driving member and connected to the adjacent end of the driving member, wherein the driving member is arranged to extend into the valve body and drive the valve core to move axially along the valve body under the drive of the stepper motor.

[0007] Preferably, in the thermostatic valve, the valve core is a temperature-bag thermostatic valve core, the end face of the temperature-bag seat of the valve core close to the driving member is set as a conical surface, and the end face of the driving member close to the temperature-bag seat is set as a conical surface or a conical surface matching the conical surface.

[0008] Preferably, in the thermostatic valve, the drive member interface is provided with a first cavity and a second cavity which are connected, the first cavity is provided at the end of the drive member interface away from the valve body, the radius of the first cavity is larger than the radius of the second cavity, the inner wall of the first cavity is provided with an internal thread, the side wall of the end of the drive member away from the valve body is provided with a protrusion, the side wall of the protrusion is provided with an external thread, and the external thread is threadedly connected to the internal thread.

[0009] Preferably, in the thermostatic valve, an annular groove is provided on the side wall of the driving member in the second cavity along its circumference, an O-ring is provided in the annular groove, and the O-ring is in sealing contact with the inner wall of the second cavity.

[0010] Preferably, in the thermostatic valve, the warm water outlet is connected to a warm water pipe joint, and the temperature sensor is arranged in the warm water pipe joint.

[0011] Preferably, in the thermostatic valve, the cold water inlet is connected to a cold water pipe joint, and a cold water check core is provided in the cold water pipe joint.

[0012] Preferably, in the thermostatic valve, the hot water inlet is connected to a hot water pipe joint, and a hot water check core is provided in the hot water pipe joint.

[0013] The present invention also provides a method for controlling a thermostatic valve, comprising:

[0014] S1, obtain the set temperature and the real-time temperature detected by the temperature sensor. If the set temperature is equal to the real-time temperature, the stepper motor is controlled not to move or to stop moving. If the set temperature is higher than the real-time temperature, enter S2. If the set temperature is lower than the real-time temperature, enter S3.

[0015] S2, heating program: take the current position of the stepper motor as the starting position, take the real-time temperature of the current position as the starting temperature and save it, then control the stepper motor to rotate in the heating direction, and obtain the stroke position of the stepper motor and the real-time temperature detected by the temperature sensor;

[0016] If the difference between the real-time temperature detected by the temperature sensor and the starting temperature reaches a first preset value during a fixed stroke of the stepper motor, the current position of the stepper motor is used as the starting position of the next fixed stroke, and the real-time temperature at the current position is used as the starting temperature of the next fixed stroke and saved, and then the stepper motor is controlled to continue to rotate in the temperature rising direction and enter the next fixed stroke, and the above process is repeated to make the real-time temperature approach the set temperature;

[0017] If the real-time temperature is greater than or equal to the set temperature during a fixed stroke of the stepper motor, then return to S1;

[0018] S3, cooling program: take the current position of the stepper motor as the starting position, take the real-time temperature of the current position as the starting temperature and save it, then control the stepper motor to rotate in the cooling direction, and obtain the stroke position of the stepper motor and the real-time temperature detected by the temperature sensor;

[0019] If the difference between the real-time temperature detected by the temperature sensor and the starting temperature reaches a second preset value during a fixed stroke of the stepper motor, the current position of the stepper motor is used as the starting position of the next fixed stroke, and the real-time temperature at the current position is used as the starting temperature of the next fixed stroke and saved, and then the stepper motor is controlled to continue to rotate in the cooling direction and enter the next fixed stroke, and the above process is repeated to make the real-time temperature approach the set temperature;

[0020] If the real-time temperature is less than or equal to the set temperature during a fixed stroke of the stepper motor, the process returns to S1.

[0021] Preferably, the control method of the thermostatic valve also includes in S2, if at the end of a fixed stroke of the stepper motor, the difference between the real-time temperature and the starting temperature is less than a first preset value, it is determined that there is no water flow, and the stepper motor is controlled to stop moving and enter S4; S3 also includes, if at the end of a fixed stroke of the stepper motor, the difference between the real-time temperature and the starting temperature is less than a second preset value, it is determined that there is no water flow, and the stepper motor is controlled to rotate in the direction of heating and enter the next fixed stroke. When the fixed stroke ends, the stepper motor is controlled to stop moving and enter S4; wherein S4 is to obtain the real-time temperature detected by the temperature sensor, if the real-time temperature is greater than the set temperature and the difference reaches a third preset value, enter S1, otherwise, the stepper motor is controlled to continue to stop moving.

[0022] The present invention has at least the following beneficial effects:

[0023] First, the present invention replaces the knob of the thermostatic valve with a stepper motor, installs a temperature sensor at the warm water outlet, and connects the stepper motor and the temperature sensor to the temperature control component, thereby achieving accurate and rapid control of the water outlet temperature of the thermostatic valve, and greatly reducing or even eliminating the cumbersome calibration process of the thermostatic valve before leaving the factory.

[0024] Second, in the thermostatic valve control method of the present invention, temperature positioning is adopted when positioning the stepper motor, that is, positioning is performed and the starting position is re-determined when the difference between the real-time temperature detected by the temperature sensor and the starting temperature meets the preset conditions. When positioning, there is no need to refer to the extreme position of the structure, nor is there any need to detect and set the initial position of the stepper motor on the structure.

[0025] Thirdly, in the thermostatic valve control method of the present invention, a water flow detection function which is indispensable in the control process can be realized by means of a simple temperature sensor.

[0026] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the structure of a thermostatic valve according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with embodiments and drawings so that those skilled in the art can implement the invention with reference to the description.

[0029] It should be understood that terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0030] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified; in the description of the present invention, the terms "lateral", "longitudinal", "upper", "lower", "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, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0031] like Figure 1As shown, the present invention provides a thermostatic valve, which includes a valve body 1 and a valve core. The valve body 1 is provided with a cold water inlet 101, a hot water inlet 102 and a warm water outlet 103. The valve core is arranged inside the valve body 1, and is characterized in that a driving member 2 is provided on the valve body 1 and is transmission-connected to the valve core. The driving member 2 is driven by a stepper motor 3 to drive the valve core to move. A temperature sensor 4 is provided on the warm water outlet 103, and the stepper motor 3 and the temperature sensor 4 are connected to a temperature control component (not shown).

[0032] In the above technical solution, the driving member connected to the valve core transmission is changed to be driven by a stepper motor, a temperature sensor is set on the warm water outlet to sense the real-time temperature of the warm water outlet, and the stepper motor and the temperature sensor are connected to the temperature control component. The temperature control component includes a controller and a human-machine interface (including a temperature control panel or PC) connected to the controller. The controller is preset with control logic. The stepper motor, temperature sensor and temperature control component form a closed-loop control circuit. When in use, the outlet water temperature (i.e., the set temperature) is set through the human-machine interface and the setting command is issued to the controller. The controller obtains the set temperature and the real-time temperature detected by the temperature sensor, and according to the built-in control logic, drives the stepper motor to perform corresponding actions, and finally makes the real-time temperature reach the required set temperature. Through the implementation of this solution, the outlet water temperature of the thermostatic valve can be visualized and controlled, and the cumbersome calibration process of the thermostatic valve before leaving the factory can be greatly reduced or even eliminated.

[0033] Specifically, the control logic built into the controller includes:

[0034] S1, obtain the set temperature and the real-time temperature detected by the temperature sensor. If the set temperature is equal to the real-time temperature, the stepper motor is controlled not to move or to stop moving. If the set temperature is higher than the real-time temperature, enter S2. If the set temperature is lower than the real-time temperature, enter S3.

[0035] S2, heating program: take the current position of the stepper motor as the starting position, take the real-time temperature of the current position as the starting temperature and save it, then control the stepper motor to rotate in the heating direction, and obtain the stroke position of the stepper motor and the real-time temperature detected by the temperature sensor;

[0036] If the difference between the real-time temperature detected by the temperature sensor and the starting temperature reaches a first preset value during a fixed stroke of the stepper motor, the current position of the stepper motor is used as the starting position of the next fixed stroke, and the real-time temperature at the current position is used as the starting temperature of the next fixed stroke and saved, and then the stepper motor is controlled to continue to rotate in the temperature rising direction and enter the next fixed stroke, and the above process is repeated to make the real-time temperature approach the set temperature;

[0037] If the real-time temperature is greater than or equal to the set temperature during a fixed stroke of the stepper motor, then return to S1;

[0038] S3, cooling program: take the current position of the stepper motor as the starting position, take the real-time temperature of the current position as the starting temperature and save it, then control the stepper motor to rotate in the cooling direction, and obtain the stroke position of the stepper motor and the real-time temperature detected by the temperature sensor;

[0039] If the difference between the real-time temperature detected by the temperature sensor and the starting temperature reaches a second preset value during a fixed stroke of the stepper motor, the current position of the stepper motor is used as the starting position of the next fixed stroke, and the real-time temperature at the current position is used as the starting temperature of the next fixed stroke and saved, and then the stepper motor is controlled to continue to rotate in the cooling direction and enter the next fixed stroke, and the above process is repeated to make the real-time temperature approach the set temperature;

[0040] If the real-time temperature is less than or equal to the set temperature during a fixed stroke of the stepper motor, the process returns to S1.

[0041] In the above control logic, when positioning the stepper motor, different from the traditional stepper motor positioning method, temperature positioning is adopted, that is, positioning is performed and the starting position is re-determined when the difference between the real-time temperature detected by the temperature sensor and the starting temperature meets the preset conditions. When positioning, there is no need to refer to the extreme position of the structure, nor is there any need to detect and set the initial position of the stepper motor on the structure.

[0042] Specifically, the traditional stepper motor positioning method uses the extreme position of the structure as the zero point or starting point. The extreme position is generally obtained by installing an extreme switch at the upper and lower extreme positions of the structure or by detecting the stall current of the stepper motor when it reaches the extreme position. In these two methods, the addition of the extreme switch requires the switch to be embedded inside the structure to detect the position of the drive or valve core, and the switch status lead is pulled out, which makes the structural design quite complicated and difficult to implement; the other method is to use the current detection method. This method determines that the stepper motor has reached the extreme position by causing the current to increase after the stepper motor reaches the extreme position. This is a commonly used stepper motor positioning method, but its disadvantage is that the strong collision and extrusion of the rigid structure will cause the structure to deform or be damaged over a long period of time, thereby causing the product to fail.

[0043] Furthermore, S2 also includes that if at the end of a fixed stroke of the stepper motor, the difference between the real-time temperature and the starting temperature is less than the first preset value, it is determined that there is no water flow, and the stepper motor is controlled to stop moving and enter S4; S3 also includes that if at the end of a fixed stroke of the stepper motor, the difference between the real-time temperature and the starting temperature is less than the second preset value, it is determined that there is no water flow, and the stepper motor is controlled to rotate in the direction of heating and enter the next fixed stroke. When the fixed stroke ends, the stepper motor is controlled to stop moving and enter S4; wherein, S4 is to obtain the real-time temperature detected by the temperature sensor. If the real-time temperature is greater than the set temperature and the difference reaches the third preset value, enter S1, otherwise, the stepper motor continues to stop moving.

[0044] In the above control logic, a simple temperature sensor can be used to realize the water flow detection function which is indispensable in the control process.

[0045] Specifically, in the process of thermostatic valve control, whether it is a heating program or a cooling program, if the water flow state cannot be accurately determined (such as no water flow when the stepper motor starts the temperature adjustment or the water flow stops during the adjustment process), the result will cause the stepper motor to continue to move and eventually reach the limit position. The most difficult problem is how to determine whether the water resumes flowing in the next period of time when the water changes from a flowing state to a stopped state. Since the warm water outlet will produce different water outlet temperature changes with the change of the stepper motor position during temperature adjustment, and when the water stops flowing, the temperature will no longer change with the change of the stepper motor position. Therefore, at the end of a fixed stroke of the stepper motor, if the difference between the real-time temperature and the starting temperature is less than the preset value, it can be determined that there is no water flow, and the stepper motor will stop moving and wait for the water outlet temperature of the warm water outlet to change to a certain extent to determine that the water flow resumes flowing and continue to adjust the temperature. Furthermore, since the cessation of water flow is detected with a delay, the water outlet temperature corresponding to the actual stroke position of the current stepper motor will be different from the real-time temperature feedback of the temperature sensor in the stroke. In order to ensure that the outlet water temperature can change to a certain extent when the water resumes flowing (the outlet water temperature rises by the third preset value) to ensure that the resumption of water flow is accurately detected, therefore, when the water flow stops flowing during the cooling program, the stepper motor stroke position must be adjusted instead of stopping immediately. This is because during the cooling adjustment, when the water flow stops flowing, the outlet water temperature corresponding to the stepper motor stroke position will be lower than the real-time temperature last fed back by the temperature sensor in the stroke, so it will not be detected when the water resumes flowing. For this reason, the stepper motor stroke position must be adjusted to a corresponding position higher than the current outlet water temperature to ensure that the water flow can be successfully detected.

[0046] In another technical solution, in the thermostatic valve, a driving member interface 104 is provided on the valve body 1, and the driving member interface 104 is perpendicular to the axis of the valve body 1. The driving member 2 is rod-shaped and inserted into the driving member interface 104. The side wall of the driving member 2 is threadedly connected to the inner wall of the driving member interface 104. The stepper motor 3 is arranged at the end of the driving member interface 104 away from the valve body 1, and the output end of the stepper motor 3 is coaxially arranged with the driving member 2 and connected to the adjacent end of the driving member 2, wherein the driving member 2 is arranged to be able to extend into the valve body 1 under the drive of the stepper motor 3 and drive the valve core to move axially along the valve body 1. Here, a structure of a driving member and a connection method between the driving member and the valve body are defined. When in use, the driving member is driven to move in the driving member interface by rotating the stepper motor, so that the end of the driving member close to the valve body is extended into the valve body or retracted into the driving member interface. During the movement of the end of the driving member close to the valve body in the valve body, the driving member contacts the valve core and pushes the valve core to move axially along the valve body, thereby realizing the change of the valve core position.

[0047] In another technical solution, the thermostatic valve, the valve core is a thermostatic valve core (existing structure), the end face of the thermostatic seat 5 of the valve core close to the driving member 2 is set as a conical surface, and the end face of the driving member 2 close to the thermostatic seat 5 is set as a conical surface or a conical surface that matches the conical surface. Here, a specific connection mode in which the driving rod drives the valve body to move is defined, when the driving member moves toward the inside of the valve body until the end face of the driving member contacts the end face of the thermostatic seat, since the contact surface is an inclined surface, the valve core will stably move along the axial direction of the valve body away from the driving member until the side wall of the driving member contacts the end face of the thermostatic seat, and when the driving member moves toward the driving member interface direction until the end face of the driving member contacts the end face of the thermostatic seat first, since the contact surface is an inclined surface, the valve core will stably move along the axial direction of the valve body toward the side close to the driving member until the end face of the driving member separates from the end face of the thermostatic seat.

[0048] In another technical solution, in the thermostatic valve, the driver interface 104 is provided with a first cavity and a second cavity that are connected, the first cavity is provided at the end of the driver interface 104 away from the valve body 1, the radius of the first cavity is greater than the radius of the second cavity, the inner wall of the first cavity is provided with an internal thread, and the side wall of the driver 2 away from the valve body 1 is provided with a protrusion 201, and the side wall of the protrusion 201 is provided with an external thread, and the external thread is threadedly connected with the internal thread. Here, the specific connection method between the driver and the driver interface is defined, and while ensuring the stability of the connection between the driver and the driver interface, the protrusion also has the function of limiting the displacement of the driver.

[0049] In another technical solution, in the thermostatic valve, the side wall of the driving member 2 located in the second cavity is provided with an annular groove along its circumference, and an O-type sealing ring 6 is provided in the annular groove, and the O-type sealing ring 6 is in sealing contact with the inner wall of the second cavity. Here, the O-type sealing ring is provided to prevent water in the valve body from entering the driving member interface.

[0050] In another technical solution, the thermostatic valve is connected to the warm water outlet 103 with a warm water pipe joint 7, and the temperature sensor 4 is disposed in the warm water pipe joint 7. Here, the warm water pipe joint is provided to facilitate connection with an external warm water pipe, and the temperature sensor is disposed in the warm water pipe joint to be applicable to the existing valve body structure.

[0051] In another technical solution, the thermostatic valve is connected to the cold water inlet 101 with a cold water pipe joint 8, and a cold water check core is provided in the cold water pipe joint 8. Here, the cold water pipe joint is provided to facilitate connection with an external cold water pipe, and a cold water check core (existing structure) is provided in the cold water pipe joint to prevent water in the valve body from flowing back into the cold water pipe joint.

[0052] In another technical solution, the thermostatic valve has a hot water pipe joint 9 connected to the hot water inlet 102, and a hot water check core (existing structure) is provided in the hot water pipe joint 9. Here, the hot water pipe joint is provided to facilitate connection with an external hot water pipe, and a hot water check core is provided in the hot water pipe joint to prevent water in the valve body from flowing back into the hot water pipe joint.

[0053] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A method for controlling a thermostatic valve, characterized in that: The thermostatic valve comprises a valve body and a valve core, the valve body is provided with a cold water inlet, a hot water inlet and a warm water outlet, the valve core is arranged inside the valve body, the valve body is provided with a driving member connected to the valve core in a transmission manner, the driving member is driven by a stepping motor to drive the valve core to move, the warm water outlet is provided with a temperature sensor, and the stepping motor and the temperature sensor are connected to a temperature control component; The control method comprises: S1, obtain the set temperature and the real-time temperature detected by the temperature sensor. If the set temperature is equal to the real-time temperature, the stepper motor is controlled not to move or to stop moving. If the set temperature is higher than the real-time temperature, enter S2. If the set temperature is lower than the real-time temperature, enter S3. S2, heating program: take the current position of the stepper motor as the starting position, take the real-time temperature of the current position as the starting temperature and save it, then control the stepper motor to rotate in the heating direction, and obtain the stroke position of the stepper motor and the real-time temperature detected by the temperature sensor; If the difference between the real-time temperature detected by the temperature sensor and the starting temperature reaches a first preset value during a fixed stroke of the stepper motor, the current position of the stepper motor is used as the starting position of the next fixed stroke, and the real-time temperature at the current position is used as the starting temperature of the next fixed stroke and saved, and then the stepper motor is controlled to continue to rotate in the temperature rising direction and enter the next fixed stroke, and the above process is repeated to make the real-time temperature approach the set temperature; If the real-time temperature is greater than or equal to the set temperature during a fixed stroke of the stepper motor, then return to S1; S3, cooling program: take the current position of the stepper motor as the starting position, take the real-time temperature of the current position as the starting temperature and save it, then control the stepper motor to rotate in the cooling direction, and obtain the stroke position of the stepper motor and the real-time temperature detected by the temperature sensor; If the difference between the real-time temperature detected by the temperature sensor and the starting temperature reaches a second preset value during a fixed stroke of the stepper motor, the current position of the stepper motor is used as the starting position of the next fixed stroke, and the real-time temperature at the current position is used as the starting temperature of the next fixed stroke and saved, and then the stepper motor is controlled to continue to rotate in the cooling direction and enter the next fixed stroke, and the above process is repeated to make the real-time temperature approach the set temperature; If the real-time temperature is less than or equal to the set temperature during a fixed stroke of the stepper motor, the process returns to S1.

2. The method for controlling a thermostatic valve according to claim 1, characterized in that: S2 also includes that if at the end of a fixed stroke of the stepper motor, the difference between the real-time temperature and the starting temperature is less than the first preset value, it is determined that there is no water flow, and the stepper motor is controlled to stop and enter S4; S3 also includes that if at the end of a fixed stroke of the stepper motor, the difference between the real-time temperature and the starting temperature is less than the second preset value, it is determined that there is no water flow, and the stepper motor is controlled to rotate in the direction of heating and enter the next fixed stroke. When the fixed stroke ends, the stepper motor is controlled to stop and enter S4; wherein, S4 is to obtain the real-time temperature detected by the temperature sensor. If the real-time temperature is greater than the real-time temperature fed back by the temperature sensor when it is determined that there is no water flow, and the difference reaches the third preset value, then enter S1, otherwise, the stepper motor is controlled to continue to stop.

Images