CN104930241B - Electric expansion valve - Google Patents

Abstract

The invention discloses an electronic expansion valve, which includes an electromagnetic coil, a valve body provided with a valve port, and a valve needle that cooperates with the valve port to regulate the flow of the electronic expansion valve. It is characterized in that the valve needle includes a main body section, The first tapered portion adjacent to the main body section, the valve port includes a straight section of equal diameter, when the electromagnetic coil applies a 0 pulse, the straight section does not contact the valve needle, and the The intersecting surface of the plane where the top of the straight section is located and the valve needle is located on the first tapered surface; the electronic expansion valve provided by the present invention can precisely adjust the flow rate in the low pulse stage, and there is no The interval of constant flow value can make full use of the small pulse area for flow adjustment, expanding the adjustment range of the electronic expansion valve.

Description

Electronic expansion valve

technical field

The invention relates to the technical field of fluid control components, in particular to an electronic expansion valve.

Background technique

In the technical field of refrigeration and heating, the electronic expansion valve is the refrigerant flow control part of the refrigeration and heating equipment. Refrigerant flow.

In some systems, when the electronic expansion valve fails when it is fully closed, or the control system fails, if the compressor continues to run, it will cause partial vacuuming of the refrigeration circuit, which will damage the compressor or even damage the entire refrigeration system. Therefore, in these systems, fully closed electronic expansion valves with flow are gradually used to replace ordinary fully closed non-flow electronic expansion valves. , still has a certain flow rate, which can effectively avoid the problem of vacuum in the refrigeration system circuit caused by the continuous operation of the compressor when the electronic expansion valve is in a fully closed state.

In the prior art, the fully closed electronic expansion valve with flow rate is usually realized by using two structures, the slot type and the gap type, which will be described respectively with reference to the accompanying drawings.

Please refer to Figure 1 and Figure 2, wherein Figure 1 is a schematic diagram of the valve needle and valve port cooperation structure during the opening process of the slotted electronic expansion valve, and Figure 2 is the flow curve of the slotted electronic expansion valve.

The so-called grooving type refers to grooving at the valve port of the electronic expansion valve, so that the sealing of the valve port is not complete. In this way, when the electronic expansion valve is in a fully closed state, the gap between the valve needle and the valve port is due to the existence of the grooving. It cannot be completely sealed, and there is still a small amount of fluid passing through the groove, so that the electronic expansion valve is fully closed and there is flow.

The valve needle 18 is provided with a sealing cone surface 181 and an adjusting cone surface 182, wherein the sealing cone surface 181 is used to contact the valve port 17 to achieve sealing or partial sealing (because the slotted type is shown in Figure 1, the valve port is provided with a slotted To maintain a certain flow, so the valve needle 18 cannot completely seal the valve port). In order to prevent self-locking, the cone angle of the sealing cone surface 181 is generally set to be greater than 45 degrees. As shown in Figure 1(a), in order to obtain and set the 0-pulse flow value, it is usually adopted to apply 0-X1 pulses to make the valve needle 18 fully contact with the valve port 17. At this time, the valve needle is in the state of closing the valve port, and the sealing cone surface 181 is in contact with the valve port 17, and its contact part is located on the sealing cone surface 181. Adjust the needle plane P2 where the junction between the tapered surfaces 182 is located (please refer to the enlarged view of Part I). In this way, combined with Figure 2, it can be seen that the flow rate in the 0~X1 pulse area is the 0 pulse flow value, which is related to the depth of the groove. In the actual processing of the groove, due to the difference in the hardness of the material itself and the processing process Therefore, the 0-pulse flow value cannot be completely controlled; in addition, the width of the 0-X1 pulse range is related to debugging, and the error during the debugging process will make X1 within a certain range. Internal fluctuations, the general error can reach 40 pulses, which will affect the adjustment accuracy of the electronic expansion valve.

Since the taper of the sealing cone 181 and the adjusting cone 182 are not consistent, the rate of change of the flow rate will be different. 17 The valve port plane P1 where the contact part is located coincides with the valve needle plane P2 where the junction between the sealing cone surface 181 and the regulating cone surface 182 is located, as shown in FIG. 1( b ). With the further upward movement of the valve needle 18, the corresponding positions of the valve needle and the valve port during the X3 pulse are shown in Figure 1(c), and finally the valve port is fully open, as shown in Figure 1(d), and the flow curve is The inflection point between X3 and X4 can be set according to actual conditions.

From the flow curve in Figure 1, it can be seen that the rate of change of the pulse flow rate in the X1~X2 section is obviously greater than the flow rate change rate required by the electronic expansion valve, so this pulse section is not available in practical applications, and because X2 is associated with X1, X2 value cannot be determined. In the end, the 0-pulse flow value of the electronic expansion valve with this structure is not easy to be accurately controlled, and the small opening area 0-X2 at the front end of the flow curve is due to the difference in the valve opening pulse. The accuracy of flow regulation is low in the low pulse area. In addition, when the electronic expansion valve with this structure is fully closed, the sealing tapered surface 181 is in contact with the valve port 17. When the electronic expansion valve is fully closed and just opened, it is easy to cause wear on the valve needle and the valve port, and may cause Stuck phenomenon.

Please refer to Figure 3 and Figure 4, wherein Figure 3 is a schematic diagram of the valve needle and valve port cooperation structure during the opening process of the gap-type electronic expansion valve, and Figure 4 is the flow curve of the gap-type electronic expansion valve.

The so-called gap type means that a section of equal diameter is set on the valve needle of the electronic expansion valve. The diameter of the equal diameter section is smaller than the diameter of the valve port, so that there will be a certain gap when the valve needle cooperates with the valve port, thus realizing the electronic expansion valve. The purpose of still having partial flow when the expansion valve is fully closed.

The valve needle 19 has an equal-diameter section 191 and an adjusting section 192. The equal-diameter section 191 is cylindrical, and the connection between the equal-diameter section 191 and the adjusting section 192 defines the valve needle plane P3. Likewise, its diameter is set to be larger than that of the equal-diameter section 191 . When the electronic expansion valve is in the fully closed position, as shown in Figure 3(a), the needle plane P3 is lower than the valve port plane P4 where the top of the valve port is located, and a There is a certain gap, and the 0-pulse flow value is guaranteed by controlling the gap value. Therefore, this structure requires high processing accuracy for the valve needle and valve port. Please refer to Figure 4, the positional relationship between the valve needle and the valve port when the X1 pulse is shown in Figure 3(b). It is related to the machining accuracy, and the error in the debugging process will cause X1 to fluctuate within a certain range, so that X1 cannot be completely controlled. In actual use, since the flow value of 0~X1 remains unchanged, and the value of X1 is uncertain, the pulse in the 0~X1 area is not available, resulting in the reduction of the available pulse domain area. Figure 3(c) and Figure 3(d) respectively show the position of the valve needle and valve port when X2 pulse and X3 pulse, whether there is an inflection point between X2 and X3 of the flow curve can be determined according to the actual situation.

It can be seen that in the fully closed electronic expansion valve with flow rate in the prior art, whether it is a slotted type or a gap type, there is a 0-pulse flow that is not easy to control accurately and there is a pulse interval with a constant flow value in the flow curve (that is, it cannot Fully utilized pulse interval), which will affect the control accuracy of the electronic expansion valve to a certain extent.

Therefore, how to design a device that can accurately control the 0-pulse flow, and can make the flow curve not include the constant flow value interval, and make full use of the small opening area of the electronic expansion valve is a technical problem to be solved urgently by those skilled in the art.

Contents of the invention

The technical problem to be solved by the present invention is to provide an electronic expansion valve, which can solve the defects in the prior art that it is not easy to accurately control the zero pulse flow rate and cannot fully utilize the pulse in the small opening area.

In order to solve the above technical problems, the present invention provides an electronic expansion valve, including:

an electromagnetic coil that applies a pulse to cause the electronic expansion valve to act in response to the pulse;

A valve body, the valve body is provided with a valve port;

A valve needle that cooperates with the valve port to regulate the flow of the electronic expansion valve;

It is characterized in that the valve needle includes a main body section and a first conical surface adjacent to the main body section, and the valve port includes a straight section with an equal diameter. When the electromagnetic coil applies a 0 pulse, the straight section The section is not in contact with the valve needle, and the intersection surface of the plane where the top end of the straight section is located and the valve needle is located on the first tapered surface.

Preferably, the valve port also has a first valve port cone surface and a second valve port cone surface, and the first valve port cone surface and the second valve port cone surface are arranged at both ends of the straight section , and all extend along the axial direction away from the straight section, and the inner diameter gradually increases.

Preferably, the plane where the boundary line between the first valve port conical surface and the straight portion is located and the intersecting surface of the valve needle are located on the first conical surface.

Preferably, the maximum diameter of the first tapered portion is greater than the inner diameter of the straight portion.

Preferably, the valve needle includes a main body section, a first valve needle cone surface, and a second valve needle cone surface arranged adjacently in sequence, and the taper of the first valve needle cone surface is larger than that of the second valve needle cone surface. Taper, the intersection surface of the plane where the top end of the straight section is located and the valve needle is located on the second valve needle taper surface.

Preferably, the valve port also has a first valve port cone surface and a second valve port cone surface, and the first valve port cone surface and the second valve port cone surface are arranged at both ends of the straight section , and all extend along the axial direction away from the straight section and the inner diameter gradually increases; the plane where the boundary line between the first valve port taper surface and the straight section is located and the intersecting surface of the valve needle Located on the second needle cone surface.

Preferably, the maximum diameter of the tapered surface of the second valve port is larger than the inner diameter of the straight section.

Preferably, the valve port includes a straight portion and a conical portion, the intersection surface of the plane where the top end of the straight portion is located and the valve needle is located on the second valve needle conical surface, and the second valve needle conical surface The maximum diameter of the face is greater than the inner diameter of the straight section.

Preferably, the valve port includes a straight section and a conical section, and the intersection surface of the plane where the top end of the straight section is located and the valve needle is located on the first conical section.

The electronic expansion valve provided by the present invention can precisely adjust the flow rate in the low pulse stage. During assembly, the relative position of the valve needle and the valve port can be adjusted, and the position of 0 pulse can be directly adjusted by using a flow meter. The flow accuracy of 0-pulse depends only on the test accuracy of the flowmeter, and has nothing to do with the manufacturing accuracy of the valve needle and valve port, which can greatly improve the consistency of 0-pulse flow and greatly reduce manufacturing costs. The flow curve of the electronic expansion valve of the present invention does not have an interval of constant flow value, therefore, the small pulse area can be fully utilized for flow adjustment, thereby expanding the adjustment range of the electronic expansion valve.

Description of drawings

Fig. 1 is a schematic diagram of the cooperation structure of the valve needle and the valve port during the valve opening process of the slotted electronic expansion valve in the prior art;

Figure 2 is the flow curve corresponding to the slotted electronic expansion valve;

Fig. 3 is a schematic diagram of the cooperation structure of the valve needle and the valve port during the valve opening process of the gap type electronic expansion valve in the prior art;

Figure 4 is the flow curve corresponding to the gap type electronic expansion valve;

Fig. 5 is a schematic structural diagram of the electronic expansion valve according to the first embodiment of the present invention;

Fig. 6 is a schematic diagram of the needle structure of the electronic expansion valve in the first embodiment;

Fig. 7 is a schematic diagram of the coordination structure of the valve needle and the valve port when the electronic expansion valve has 0 pulses in the first embodiment;

Fig. 8 is a schematic diagram of the cooperation structure between the valve needle and the valve port when the electronic expansion valve is opened in the first embodiment;

Fig. 9 is a flow chart of the electronic expansion valve in the first embodiment;

Fig. 10 is a schematic diagram of the cooperation structure between the valve needle and the valve port of the electronic expansion valve according to the second embodiment of the present invention;

Fig. 11 is a schematic diagram of the cooperation structure between the valve needle and the valve port of the electronic expansion valve in the third embodiment of the present invention;

Fig. 12 is a schematic diagram of the cooperation structure between the valve needle and the valve port of the electronic expansion valve in the fourth embodiment of the present invention;

Fig. 13 is a schematic diagram of the cooperation structure between the valve needle and the valve port of the electronic expansion valve in the fifth embodiment of the present invention;

Fig. 14 is a schematic diagram of the cooperation structure between the valve needle and the valve port of the electronic expansion valve in the sixth embodiment of the present invention.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

first embodiment

Please refer to Figure 5 and Figure 6. 5 is a schematic structural diagram of the electronic expansion valve according to the first embodiment of the present invention, and FIG. 6 is a schematic structural diagram of the valve needle of the electronic expansion valve according to the first embodiment.

As shown in Figure 5, the electronic expansion valve includes a valve body 1 and a coil (not shown in the figure). Take over the pipe 13, and the upper part of the valve seat 11 is also fixedly connected with the casing 14. Inside the casing 14, a magnetic rotor 15 that rotates in response to the signal of the coil, a screw 16 that is fixedly connected with the magnetic rotor 15, and a screw that cooperates with the screw , convert the rotary motion of the screw mandrel into the nut 17 of the lifting motion. The screw rod 16 is connected with the valve needle 21, and the valve needle 21 cooperates with the valve port 22 provided on the valve seat 11 during the lifting movement, so as to realize the opening and closing of the electronic expansion valve. In order to set the top dead center and bottom dead center of the valve needle's lifting movement, a stop device 18 is also provided to limit it.

It should be pointed out that the electronic expansion valve shown in Figure 5 is only a specific embodiment, which is introduced for the convenience of explaining the working principle of the electronic expansion valve. Based on the above working principle, various structural changes and Improvement, the core of the present invention is to provide a matching structure between the valve needle and the valve port of the electronic expansion valve, which is applicable to any electronic expansion valve based on the above working principle, therefore, the above description of the structure of the electronic expansion valve does not protect the present invention any limitation in scope.

The valve needle structure will be described below with reference to FIG. 6 .

The valve needle 21 includes a main body section 211 connected with the screw rod, a first valve needle cone surface 212 connected with the main body section 211 and a second valve needle cone surface 213 connected with the first valve needle cone surface 212, the three are adjacent in sequence set up. Wherein, the first needle cone surface 212 is used to cooperate with the valve port to determine the valve closing state and the 0-pulse flow rate, and the first valve needle cone surface 212 and the second valve needle cone surface 213 jointly regulate the flow rate of the valve port. Both the first needle cone surface 212 and the second valve needle cone surface 213 have a cone structure, and the taper of the first valve needle cone surface 212 is larger than that of the second valve needle cone surface 213 . In this way, a boundary line is formed along the circumference at the junction of the two, and the plane of the boundary line defines the first plane N1. The third valve needle cone surface 214 located at the bottom end of the valve needle is used to control the inflection point between X1-X2 pulses in the flow curve shown in FIG. 9 .

Fig. 7 is a schematic diagram of the cooperative structure of the valve needle 21 and the valve port 22 when the electronic expansion valve has 0 pulses. The tapered surface 223, wherein the straight portion 222 is generally cylindrical, the first valve port tapered surface 221 and the second valve port tapered surface 223 extend along the axial direction away from the straight portion 222, and gradually increase the inner diameter, so that Form an inner cone shape. The junction of the first taper surface 221 of the valve port and the straight portion 222 also forms a junction line. For the convenience of description, the plane where the junction line is located is defined as the second plane N2, as shown in FIG. 7 .

At 0 pulse, the first plane N1 is higher than the second plane N2, and for the valve needle 21, the intersecting surface of the second plane N2 and the valve needle 21 is located on the second valve needle cone surface 223 of the valve needle 21, at this time , the first valve needle cone surface 212 is not in contact with the first valve port cone surface 221, and the cross-sectional diameter D1 of the valve needle 21 on the first plane N1 is larger than the cross-sectional inner diameter D2 of the valve port 22 on the second plane N2, so that the Small enough traffic. The second valve needle cone surface 213 cooperates with the straight portion 222 to adjust the flow rate by rotating the valve needle 21 . As the valve needle 21 rises, it reaches the position shown in FIG. 8 . The flow curve formed according to the above structural features is shown in FIG. 9 . That is, the flow rate of the flow curve is greater than 0 at 0 pulses, and the curve rises according to a certain slope until the valve needle is fully open. It can be seen that the electronic expansion valve can accurately adjust the flow rate in the low pulse stage.

When the electronic expansion valve is assembled, the relative position of the valve needle and the valve port can be adjusted, and the position of 0 pulse can be directly adjusted by the flow meter. That is, connect the flowmeter to the electronic expansion valve to take over, and then control the rotation of the valve needle. When the 0 pulse is debugged, the relative position of the valve needle and the valve port will make the electronic expansion valve have a certain initial flow rate. In this way, the electronic expansion valve provided by the present invention Valve, the flow accuracy of 0 pulse depends only on the test accuracy of the flowmeter, and has nothing to do with the manufacturing accuracy of the valve needle and valve port, which can greatly improve the consistency of the 0 pulse flow.

At the same time, since the cross-sectional diameter D1 of the valve needle 21 on the first plane N1 (that is, the maximum diameter of the second needle cone surface) is greater than the internal diameter D2 of the cross-section of the valve port 22 on the second plane N2 (that is, the internal diameter of the straight section of the valve port) , in theory, D1 can be designed to be infinitely close to D2. In other words, the gap between the valve needle and the valve port can be infinitely reduced at 0 pulses, that is, the flow rate of 0 pulses is set to be infinitely small. In this way, it is especially suitable for R32 refrigerants, refrigerators, and water heaters. It can be used in some special refrigeration systems, which can increase the range of use of electronic expansion valves.

In order to improve the consistency of the 0-pulse flow rate, the angle of the second tapered surface 213 can be set to be less than 15°. If the angle is too large, the inconsistency of the 0-pulse flow rate will be increased. When the valve body is fully closed, as shown in Figure 7, the valve port 22 is located below the first plane N1. During the valve body opening process, the valve port directly cooperates with the second tapered surface 213 of the valve needle 21 to adjust the flow rate, while Regardless of the first cone surface 212, in this way, the flow in the small opening area of the electronic expansion valve can be controlled, and in the system, the small opening area is available.

In the electronic expansion valve provided by this embodiment, there is no interval of constant flow value in the flow curve, therefore, the small pulse area can be fully utilized for flow adjustment, thereby expanding the adjustment range of the electronic expansion valve. At the same time, when the valve needle is in the fully closed state, the valve needle does not contact the valve port, thereby avoiding the wear of the valve needle and the valve port.

Other embodiments of the present application will be described below with reference to the accompanying drawings 10-14. To facilitate description of the differences between other embodiments and the first embodiment, components with the same structure and function are given the same reference numerals.

second embodiment

Please refer to FIG. 10 . FIG. 10 is a schematic diagram of the cooperation structure between the valve needle and the valve port of the electronic expansion valve according to the second embodiment of the present invention.

In this embodiment, the structure of the valve port 22 is the same as that of the first embodiment, including a first valve port conical surface 221, a straight portion 222 and a second valve port conical surface 223 arranged in sequence, wherein the straight portion 222 is generally in the shape of Cylindrical, the first valve port cone surface 221 and the second valve port cone surface 223 both extend along the axial direction away from the straight portion 222 , and gradually increase the inner diameter, thereby forming an inner cone shape. The junction of the first taper surface 221 of the valve port and the straight portion 222 forms a junction line, and the plane where it is located is the second plane N2.

The valve needle 31 includes a main body 311 and a first conical surface 312 connected to the main body. The maximum diameter of the first conical surface 312 is larger than the inner diameter of the straight portion 222 of the valve port. At the 0 pulse position, the intersecting surface of the second plane N2 and the valve needle 31 is located on the first tapered surface 312 .

The zero-pulse position adjustment method in this embodiment is the same as that in the first embodiment, and will not be repeated here.

third embodiment

Please refer to FIG. 11 . FIG. 11 is a schematic diagram of the coordination structure between the valve needle and the valve port of the electronic expansion valve according to the third embodiment of the present invention.

In this embodiment, the valve needle 21 is the same as the first embodiment, including a main body section 211 connected with the screw rod, a first valve needle cone surface 212 connected with the main body section 211 and a valve needle cone surface 212 connected with the first valve needle cone surface 212 . The second valve needle cone surface 213 and the third valve needle cone surface 214 can be set according to the requirement of flow regulation.

The valve port 32 is generally a hollow cylindrical straight section 321 without any conical surface. The maximum diameter of the second needle conical surface 213 is larger than the inner diameter of the straight section 321 . The top of the valve port defines a second plane N2 , and the intersecting surface of the second plane N2 and the valve needle 21 is located on the second needle cone surface 213 of the valve needle 21 . The zero-pulse position adjustment method in this embodiment is the same as that in the first embodiment, and will not be repeated here.

Fourth Embodiment

Please refer to FIG. 12 . FIG. 12 is a schematic diagram of the cooperation structure between the valve needle and the valve port of the electronic expansion valve in the fourth embodiment of the present invention.

In this embodiment, the valve needle 21 is the same as the first embodiment, including a main body section 211 connected with the screw rod, a first valve needle cone surface 212 connected with the main body section 211 and a valve needle cone surface 212 connected with the first valve needle cone surface 212 . The second needle cone surface 213 .

The valve port 42 includes a substantially hollow cylindrical straight portion 421 and a conical portion 422 adjacent to the straight portion. The inner diameter of the straight portion 421 is smaller than the maximum diameter of the second needle conical surface 213 . The top end of the straight portion 421 defines a second plane N2 , and the intersecting surface of the second plane N2 and the valve needle 21 is located on the second needle cone surface 213 of the valve needle 21 .

Fifth Embodiment

Please refer to FIG. 13 . FIG. 13 is a schematic diagram of the cooperation structure between the valve needle and the valve port of the electronic expansion valve in the fifth embodiment of the present invention.

In this embodiment, the valve port 32 is the same as the third embodiment, the whole is a hollow cylindrical straight section 321 without a tapered portion, and the top of the valve port defines a second plane N2. The structure of the valve needle 31 is the same as that of the second embodiment, including a main body 311 and a first conical surface 312 connected to the main body. The maximum diameter of the first conical surface 312 is larger than the inner diameter of the straight section 321 .

At the 0 pulse position, the intersecting surface of the second plane N2 and the valve needle 31 is located on the first tapered surface 312 . The intersection surface of the second plane N2 and the valve needle 21 is located on the second needle cone surface 213 of the valve needle 21 .

Sixth Embodiment

Please refer to Fig. 14, Fig. 14 is a schematic diagram of the coordination structure between the valve needle and the valve port of the electronic expansion valve in the sixth embodiment of the present invention;

In this embodiment, the structure of the valve port is the same as that of the fourth embodiment. The valve port 42 includes a substantially hollow cylindrical straight section 421 and a conical surface 422 adjacent to the straight section. The top of the straight section 421 A second plane N2 is defined.

The structure of the valve needle 31 is the same as that of the second embodiment. The valve needle 31 includes a main body 311 and a first conical surface 312 connected to the main body. The maximum diameter of the first conical surface 312 is larger than the inner diameter of the straight section 421 . The intersection surface of the second plane N2 and the valve needle 21 is located on the second needle cone surface 213 of the valve needle 21 .

It should be added that, in the above-mentioned embodiment, the bottom end of the valve needle is also provided with a section of tapered end, which is used to control whether the X1-X2 pulses in the flow curve shown in Figure 9 There is an inflection point. Because it has little influence on the flow regulation in the low pulse stage, it is not described in detail in the above embodiments.

The electronic expansion valve provided by the present invention has been introduced in detail above. In this paper, specific examples are used to illustrate the principle and implementation of the present invention, and the descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims (9)

1. electric expansion valve, including：

Electromagnetic coil, the electromagnetic coil apply pulse, the electric expansion valve response impulse are made to be acted；

Valve body offers valve port on the valve body；

Coordinate to carry out the needle of flow-rate adjustment to the electric expansion valve with valve port；

It is characterized in that,

The first conical surface portion that the needle includes main paragraph, is disposed adjacent with the main paragraph, the valve port include one isometrical Straight section portion, when the electromagnetic coil apply 0 pulse when, the straight section portion is not contacted with the needle, and the straight section portion Top where the intersection of plane and the needle be located in first conical surface portion.

2. electric expansion valve as described in claim 1, which is characterized in that the valve port also has the first valve port conical surface, second The valve port conical surface, the first valve port conical surface and the second valve port conical surface are arranged at the both ends in the straight section portion, and each along the back of the body Axial direction from the straight section portion extends and internal diameter gradually increases.

3. electric expansion valve as claimed in claim 2, which is characterized in that the friendship of the first valve port conical surface and the straight section portion Plane and the intersection of the needle where boundary line are located in first conical surface portion.

4. the electric expansion valve as described in claim 1 or 3, which is characterized in that the maximum gauge of first conical surface portion is more than The internal diameter in the straight section portion.

5. electric expansion valve, including：

Electromagnetic coil, the electromagnetic coil apply pulse, the electric expansion valve response impulse are made to be acted；

Valve body offers valve port on the valve body；

Coordinate to carry out the needle of flow-rate adjustment to the electric expansion valve with valve port；

It is characterized in that, the needle includes the main paragraph being disposed adjacent successively, the first needle conical surface, the second needle conical surface, institute The taper for stating the first needle conical surface is more than the taper of the second needle conical surface, and the valve port includes an isometrical straight section portion, When the electromagnetic coil applies 0 pulse, the straight section portion is not contacted with the needle, plane where the top in the straight section portion It is located on the second needle conical surface with the intersection of the needle.

6. electric expansion valve as claimed in claim 5, which is characterized in that the valve port also has the first valve port conical surface, second The valve port conical surface, the first valve port conical surface and the second valve port conical surface are arranged at the both ends in the straight section portion, and each along the back of the body Axial direction from the straight section portion extends and internal diameter gradually increases；The boundary of the first valve port conical surface and the straight section portion Plane and the intersection of the needle where line are located on the second needle conical surface.

7. such as electric expansion valve described in claim 5 or 6, which is characterized in that the maximum gauge of the second valve port conical surface is big Internal diameter in the straight section portion.

8. electric expansion valve as claimed in claim 5, which is characterized in that the valve port includes straight section portion and conical surface portion, described Plane where the top in straight section portion and the intersection of the needle are located on the second needle conical surface, the second needle conical surface Maximum gauge be more than the straight section portion internal diameter.

9. electric expansion valve as described in claim 1, which is characterized in that the valve port includes straight section portion and conical surface portion, described Plane where the top in straight section portion and the intersection of the needle are located in first conical surface portion.