Electronic expansion valve

Abstract

This invention relates to an electronic expansion valve, comprising a drive magnet rotated by a stepper motor. The drive magnet is a hollow cylindrical shape surrounding a rotor assembly of the electronic expansion valve. Multiple N and S poles are circumferentially spaced on the inner surface of the hollow cylindrical shape. A protective sleeve is arranged between the drive magnet and the rotor assembly of the electronic expansion valve. The rotor assembly includes a rotor magnet and a screw connected to the rotor magnet. The drive magnet faces the rotor magnet inside the rotor assembly. The rotational motion of the drive magnet drives the rotation of the rotor magnet inside the rotor assembly. The screw of the rotor assembly is provided with threads for converting the rotational motion of the rotor assembly into the up-and-down movement of a valve needle, thereby adjusting the area of ​​the throttling orifice of the electronic expansion valve. This electronic expansion valve has higher precision and reliability, lower manufacturing cost, and allows for more reliable closed-loop control.

Description

Technical Field

[0001] This invention relates to an electronic expansion valve, and more particularly to an electronic expansion valve for use in a vehicle refrigerant circuit. Background Technology

[0002] In the cooling circuit, the stepper motor type electronic expansion valves used mostly employ a constant voltage drive unipolar control method using the stepper motor's built-in coil: each winding of the coil has two phases, and the controller energizes each winding in a predetermined sequence through leads, causing the rotor assembly inside the electronic expansion valve to rotate in the required number of steps, which causes the valve needle of the electronic expansion valve to move up and down, adjusting the throttling orifice area of ​​the electronic expansion valve, thereby achieving control of the cooling capacity.

[0003] Because the rotor assembly of the electronic expansion valve is located in the coolant, a protective sleeve is placed between the rotor assembly and the stepper motor coil in a conventional stepper motor-type electronic expansion valve. Due to the space occupied by the protective sleeve, the magnetic field strength generated by the stepper motor coil windings is significantly weakened after penetrating the protective sleeve. Therefore, in order to generate a sufficiently large magnetic torque, the size of the magnets in the stepper motor coil and rotor assembly also needs to be designed to be large. As a result, the stepper motor and rotor assembly of the electronic expansion valve are large in size and weight, resulting in high material costs. On the other hand, due to the limited number of claw poles on the motor stator, the number of magnetic poles is small. To ensure positioning accuracy, the pitch of the drive thread in the rotor assembly is small and precise. The screw with drive thread is difficult to manufacture and is prone to jamming due to manufacturing errors or contaminants. Furthermore, because the rotational speed of the stepper motor is low, it is difficult to determine the position of the expansion valve rotor assembly by the induced electromotive force of the motor, and it is also difficult to complete the closed-loop control of the expansion valve adjustment through other structures.

[0004] Another type of expansion valve exists in the prior art, which includes a drive system connected to a stepper motor drive shaft. The drive system drives a rotating shaft that passes through the housing of the expansion valve. The rotation of the rotating shaft causes the valve needle to move up and down, adjusting the throttling orifice area of ​​the electronic expansion valve, thereby controlling the amount of refrigerant. In this type of expansion valve, because the rotating shaft passes through the housing of the expansion valve, the refrigerant in the expansion valve is very easy to leak. Summary of the Invention

[0005] To overcome some or all of the above-mentioned defects, this invention proposes an electronic expansion valve that uses a magnet driven by a stepper motor to drive the rotor assembly inside the electronic expansion valve, thereby improving the accuracy of the electronic expansion valve and significantly reducing its manufacturing cost.

[0006] This invention relates to an electronic expansion valve, comprising a drive magnet rotated by a stepper motor. The drive magnet is a hollow cylindrical shape surrounding a rotor assembly of the electronic expansion valve. Multiple magnetic poles are circumferentially spaced on the inner surface of the hollow cylindrical shape. The rotor assembly includes a rotor magnet and a screw connected to the rotor magnet. The rotor magnet within the rotor assembly is located within the cylindrical space of the drive magnet and has multiple circumferentially spaced magnetic poles opposite to the magnetic poles of the drive magnet. The rotational motion of the drive magnet drives the rotor magnet within the rotor assembly to rotate. The screw of the rotor assembly is provided with threads for converting the rotational motion of the rotor assembly into linear motion of a valve needle, thereby adjusting the area of ​​the throttling orifice of the electronic expansion valve. The electronic expansion valve of this invention utilizes a drive magnet to drive the rotor assembly, providing both a large driving torque and solving the fluid sealing problem.

[0007] The electronic expansion valve may include the following advantages:

[0008] Preferably, a transmission gear system is provided between the stepper motor and the drive magnet. The transmission gear system is a reduction gear system. The input side of the transmission gear system is connected to the drive shaft of the stepper motor, and the output side of the transmission gear system is connected to the drive magnet. By transmitting power between the stepper motor and the drive magnet through the reduction gear system, the stepper motor can rotate at a higher speed. Therefore, the stepper motor can provide a higher induced electromotive force, which can provide a more accurate measurement of the position of the rotor assembly.

[0009] Preferably, the reduction gear system is a two-stage reduction gear system, which can greatly reduce the rotational speed;

[0010] Preferably, a protective sleeve is arranged between the drive magnet and the rotor assembly of the electronic expansion valve to seal the rotor assembly, thereby providing a fluid seal for the electronic expansion valve;

[0011] Preferably, the driving magnet is made of ferrite, which is inexpensive and can effectively reduce production costs;

[0012] Preferably, the outer surface of the driving magnet is provided with two rows of N and S poles arranged in an alternating manner, and a Hall sensor is provided near the driving magnet. The Hall sensor senses the position of the driving magnet and thus determines the opening degree of the electronic expansion valve.

[0013] More preferably, the Hall sensor is arranged at different positions around the drive magnet, so as to effectively determine the circumferential position of the drive magnet and thus accurately determine the opening degree of the expansion valve.

[0014] Preferably, the control circuit acquires the induced electromotive force generated by the stepper motor for closed-loop control of the electronic expansion valve;

[0015] Preferably, the housing surrounding the stepper motor and the housing surrounding the drive magnet are formed as a single upper housing, which makes the overall structure simpler.

[0016] More preferably, the housing surrounding the stepper motor also includes a connector interface integral with the housing, through which the stepper motor can be controlled.

[0017] According to the electronic expansion valve of the present invention, a driving magnet is used instead of a coil in a stepper motor to drive the rotor assembly, which makes the stepper motor used in the electronic expansion valve smaller in size, while increasing the transmission efficiency and accuracy of the electronic expansion valve, reducing the risk of internal jamming and reducing manufacturing costs, and improving more flexible, reliable and low-cost closed-loop control. Attached Figure Description

[0018] Figure 1 This is a perspective view of the electronic expansion valve according to the present invention;

[0019] Figure 2 This is a top perspective view of the upper housing portion of the electronic expansion valve according to the present invention;

[0020] Figure 3 This is a partial cross-sectional view of the electronic expansion valve according to the present invention, with the upper and lower housings removed.

[0021] Figure 4 A perspective view of the transmission gear train is shown by removing the cover plate on the top of the upper housing of the electronic expansion valve according to the present invention;

[0022] Figure 5 The diagram shows a perspective view of the transmission gear train by removing the upper housing of the electronic expansion valve according to the present invention.

[0023] Figure 6 This is an overall layout diagram of the electronic expansion valve according to the present invention;

[0024] Figure 7 This is a diagram showing the magnetic pole arrangement of the drive magnet and rotor magnet of the electronic expansion valve according to the present invention. Detailed Implementation

[0025] The following is combined with Figures 1 to 6 The embodiments of the present invention will be described in detail. For example... Figure 1 and 2 As shown, an electronic expansion valve according to an embodiment of the present invention includes an upper housing portion 100 and a lower housing portion 200. The upper housing portion 100 includes an upper housing 101 that covers the entire upper housing portion. The upper housing 101 includes a connector member 105 for receiving a connector member 105. Figure 5The connector interface 102 (shown in Figure 1) is integrally formed with the upper housing 101. The connector interface 102 is connected to the stepper motor 103 to control the rotation of the stepper motor. The lower housing portion 200 (i.e., the valve body portion) includes a lower housing 201 having fluid inlet / outlet ports 202 thereon, the fluid specifically referring to refrigerant flowing in the refrigeration circuit. The upper housing 101 is fixed to the lower housing 201 by screws or other fixing members. The improvement of the electronic expansion valve according to the present invention is mainly concentrated in the upper housing portion 100 shown in Figure 1.

[0026] like Figure 3 As shown, the electronic expansion valve according to the present invention includes a drive magnet 203 rotatably driven by the shaft 104 of a stepper motor 103. The drive magnet 203 is shaped as a hollow cylindrical shape surrounding the rotor assembly of the electronic expansion valve. The inner surface of the hollow cylindrical shape has a plurality of N / S magnetic poles spaced circumferentially. Unlike conventional electronic expansion valves, this drive magnet 203 with multiple magnetic poles drives the rotor assembly in the electronic expansion valve to rotate, rather than being directly driven by the coils in the stepper motor. (As shown in...) Figure 3 As shown, the coil (stator) and shaft of the stepper motor according to the present invention are compactly arranged within the motor housing. Since the coil in the stepper motor does not directly drive the rotor assembly, but rather drives the shaft 104 of the stepper motor 103, the stepper motor 103 according to the present invention can have a smaller size, and in particular, the size and weight of the coil in the stepper motor 103 can be significantly reduced compared to a direct-drive electronic expansion valve. In one embodiment, the weight of the coil can be 1 / 10 of the weight of the coil in a direct-drive electronic expansion valve, and the weight of the upper housing portion 100 is half that of the corresponding portion in a direct-drive electronic expansion valve. Therefore, less material (e.g., copper and rare-earth magnetic materials) can be used inside the motor, thus significantly reducing manufacturing costs.

[0027] As in Figure 3As shown in detail, a protective sleeve 204 is disposed between the drive magnet 203 and the rotor assembly of the electronic expansion valve, the rotor assembly including a rotor magnet 205 and a screw 206 connected to the rotor magnet 205. The protective sleeve 204 provides a fluid seal for the electronic expansion valve. The rotor magnet 205 is cylindrical, and the screw 206 is fixed at the center of the rotor magnet. The drive magnet 203 faces the rotor magnet 205 of the rotor assembly within the space enclosed by the drive magnet 203, forming a magnetic field between the drive magnet 203 and the rotor magnet 205. When the stepper motor 103 drives the drive magnet 203 to rotate, the movement of the drive magnet 203 drives the rotor magnet 205 in the rotor assembly to rotate synchronously. The rotor magnet 205 then drives the screw 206 to rotate. The screw 206 is provided with a thread 207 for converting the rotational motion of the rotor assembly into the linear motion of the valve needle (not shown) to adjust the area of ​​the throttle orifice of the electronic expansion valve. In the embodiment shown in the figure, the linear motion of the valve needle is an up-and-down linear motion.

[0028] Because of the use of the drive magnet 203, unlike the original coil in the stepper motor 103, a larger excitation magnetic field can be used in the drive magnet 203. Therefore, the magnetic field strength formed in the drive magnet 203 and the rotor magnet 205 is very high, so the size of the rotor magnet 205 used to generate the drive torque for rotating the drive screw 206 can be reduced. In particular, the length of the rotor magnet 205 can be shortened, improving transmission reliability. The drive magnet 203 can use common ferromagnetic materials, while the rotor magnet 205 is generally made of rare earth materials. In one embodiment, the weight and length of the rare earth rotor magnet 205 are half that of a direct-drive electronic expansion valve. Benefiting from the significant reduction in weight and length of the rare earth rotor magnet 205, the cost of this electronic expansion valve is greatly reduced.

[0029] A transmission gear train is provided between the rotating shaft 104 of the stepper motor 103 and the driving magnet 203. Preferably, the transmission gear train is a reduction gear train. Figures 3 to 5 In the specific example shown, the reduction gear train is a two-stage reduction gear train. It is conceivable that the reduction gear train can have more stages, such as three or four stages. In the specific embodiment shown in the figure, the two-stage reduction gear train consists of a first gear S1, a second gear S2, a fourth gear S3, and a fourth gear S4. The first gear S1 is connected to the shaft 104 of the stepper motor 103 and is thus driven. A drive magnet 203 is fixedly connected to the fourth gear S4, meaning that the drive magnet 203 is driven by the fourth gear S4. The meshing relationship of the reduction gear train is... Figure 4 and Figure 5The following is shown in more detail. Compared to conventional solutions where a stepper motor only requires a few dozen steps to drive the rotor magnet in the rotor assembly of an electronic expansion valve to rotate once, the stepper motor of the electronic expansion valve according to the present invention requires more steps to rotate the rotor magnet 205 once due to the use of a reduction gear system. Therefore, the pitch of the thread 207 on the screw 206 driven by the rotor magnet 205 can be set to be larger. The screw 206 with a larger pitch is more reliable than the screw 206 with a smaller pitch. Due to the larger pitch, higher transmission efficiency and reliability can be provided, reducing the risk of internal jamming of the valve body. In one embodiment, compared to a conventional direct-drive electronic expansion valve, the number of steps required for the rotor magnet 205 to rotate once is increased by three times, the thread pitch is doubled, the thread efficiency is doubled, the motor speed is doubled, and ultimately, for the same stroke, the number of valve opening steps is still doubled. Therefore, thanks to the reduction gear system, the motor achieves a higher operating speed, the increased thread pitch improves reliability, and the valve opening accuracy is improved.

[0030] The upper housing 101 covering the stepper motor 103 and the drive magnet 203 is made into a single piece. The upper housing 101 also includes a connector interface 102 covering the connector 104. The connector interface 102 covering the connector 104 is formed into a single piece with the upper housing 101. The upper housing 101 is preferably integrally injection molded, thereby reducing manufacturing complexity.

[0031] In one embodiment, two rows of N / S poles are arranged alternately on the outer surface of the driving magnet 203. The N / S poles are arranged circumferentially at intervals and alternately between the two rows, as shown in the specific arrangement below. Figure 6 As shown, the N / S poles occupy the entire circumference of the drive magnet 203, thereby providing the circumferential magnetic field strength during rotation. The two rows of N / S poles on the outer surface of the drive magnet 203 are used to sense the position of the drive magnet 203. Due to the mutual attraction between the inner surface of the drive magnet 203 and the rotor magnet 205, the drive magnet 203 and rotor magnet 205 have a positional correspondence. Therefore, the position of the drive magnet 203 can be used to determine the relationship with the rotor magnet 205, and thus determine the opening degree of the electronic expansion valve. Figure 7As shown, multiple N / S magnetic poles (right side of the figure) on the inner surface of the hollow cylindrical shape of the drive magnet 203 and multiple N / S magnetic poles (left side of the figure) on the outer surface of the rotor magnet 205 are uniformly arranged circumferentially, and the magnetic poles on the drive magnet 202 and the rotor magnet 205 have a corresponding relationship. For example, a pair of arrows in the figure show the correspondence of a pair of magnetic poles, with the N pole of the rotor magnet 205 indicated by the arrow facing the S pole of the drive magnet 202 indicated by the arrow. The positional correspondence between the drive magnet 203 and the rotor magnet 205 is synchronous, that is, when the drive magnet 203 rotates one revolution, the rotor magnet 205 also rotates one revolution. To determine the position of the drive magnet 203, a Hall sensor (not shown; in one embodiment, two Hall sensors) is placed near the magnetic poles on the outer surface of the drive magnet 203. The Hall sensor is connected to a controller (the controller includes, for example, a PCB) to sense the opening degree of the expansion valve. Furthermore, the controller can also be connected to the control terminal of the stepper motor to realize closed-loop control of the electronic expansion valve. Preferably, in order to sense different angular positions of the driving magnet 203, the Hall sensor is arranged at different circumferential positions of the driving magnet 203.

[0032] In one embodiment, the back electromotive force of the stepper motor 103 is collected by a chip to determine whether the stepper motor has lost steps or jammed, thereby allowing for appropriate software strategies to resolve the problem. Because the electronic expansion valve according to the invention is equipped with a reduction gear system connected to the stepper motor 103, and because the motor core and motor coil are compactly arranged within the stepper motor housing, the stepper motor of the electronic expansion valve according to the invention has a higher rotational speed and a smaller gap between the stepper motor core and coil (stepper motor stator) compared to prior art electronic expansion valves, thus obtaining a higher back electromotive force value and improving the accuracy of closed-loop control.

[0033] Various modifications and variations can be made to the embodiments disclosed above without departing from the scope or spirit of the invention. Other embodiments of the invention will be apparent to those skilled in the art based on the practice of the invention disclosed in this specification. This specification and the examples disclosed herein should be considered illustrative only, and the true scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An electronic expansion valve, characterized in that, The device includes a drive magnet driven by a stepper motor. The drive magnet is a hollow cylindrical shape surrounding a rotor assembly of an electronic expansion valve. Multiple magnetic poles are spaced circumferentially on the inner surface of the hollow cylindrical shape. The rotor assembly includes a rotor magnet and a screw connected to the rotor magnet. The rotor magnet inside the rotor assembly is located within the cylindrical space of the drive magnet and has multiple magnetic poles spaced circumferentially opposite to the magnetic poles of the drive magnet. The rotational motion of the drive magnet drives the rotor magnet inside the rotor assembly to rotate. The screw of the rotor assembly is provided with threads for converting the rotational motion of the rotor assembly into linear motion of the valve needle, thereby adjusting the area of ​​the throttle orifice of the electronic expansion valve.

2. The electronic expansion valve according to claim 1, characterized in that, A transmission gear system is provided between the stepper motor and the drive magnet. The transmission gear system is a reduction gear system. The input side of the transmission gear system is connected to the drive shaft of the stepper motor, and the output side of the transmission gear system is connected to the drive magnet.

3. The electronic expansion valve according to claim 1, characterized in that, A protective sleeve is arranged between the rotor assembly of the drive magnet and the electronic expansion valve to seal the rotor assembly.

4. The electronic expansion valve according to claim 1, characterized in that, The driving magnet is made of ferrite and magnetized.

5. The electronic expansion valve according to claim 1, characterized in that, The outer surface of the driving magnet is provided with two rows of N and S poles arranged in an alternating pattern.

6. The electronic expansion valve according to claim 1 or 5, characterized in that, A Hall sensor is placed near the driving magnet, which senses the position of the driving magnet to determine the opening degree of the electronic expansion valve.

7. The electronic expansion valve according to claim 6, characterized in that, The Hall sensor is arranged at different positions around the drive magnet.

8. The electronic expansion valve according to claim 1, characterized in that, The control circuit collects the induced electromotive force generated by the stepper motor for closed-loop control of the electronic expansion valve.

9. The electronic expansion valve according to claim 1, characterized in that, The housing surrounding the stepper motor and the housing surrounding the drive magnet are made as a single unit.

10. The electronic expansion valve according to claim 9, characterized in that, The housing surrounding the stepper motor also includes a connector interface integral with the housing.

11. The electronic expansion valve according to claim 2, characterized in that, The reduction gear system is a two-stage reduction gear system.

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