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CN-121993621-A - Electronic expansion valve with heterogeneous metal sealing pair

CN121993621ACN 121993621 ACN121993621 ACN 121993621ACN-121993621-A

Abstract

The invention provides an electronic expansion valve with a heterogeneous metal sealing pair, which comprises a valve body, a valve head arranged on the valve body, a valve needle arranged in the valve body in a reciprocating manner, and a valve seat fixed in the valve body and provided with a valve port. The valve head is in driving connection with the valve needle, and the valve head drives the valve needle to reciprocate in the valve body. The valve needle is provided with a conical sealing part matched with the valve port of the valve seat, and the conical sealing part of the valve needle forms a conical sealing pair matched with the valve port of the valve seat. The conical sealing part of the valve needle is provided with a first coating, the surface of the valve port of the valve seat is provided with a second coating, and the materials of the first coating and the second coating are different. The valve needle and the valve seat are of a paired matched grinding structure. According to the invention, the first coating is arranged on the conical sealing part of the valve needle, the second coating is arranged on the valve port surface of the valve seat, and the materials of the first coating and the second coating are different, so that the phenomenon of cold welding of homogeneous metal generated when the valve needle and the valve seat are in hard sealing contact with each other is avoided, and the sealing effect is ensured.

Inventors

  • WANG HENG
  • Wei Zixue
  • JIANG JINLIN

Assignees

  • 太仓京和机电有限公司

Dates

Publication Date
20260508
Application Date
20260320

Claims (8)

  1. 1. The electronic expansion valve with the heterogeneous metal sealing pair is characterized by comprising a valve body (1), a valve head (2) arranged on the valve body (1), a valve needle (3) reciprocatingly arranged in the valve body (1) and a valve seat (4) fixed in the valve body (1) and provided with a valve port, wherein the valve head (2) is in driving connection with the valve needle (3), and the valve head (2) drives the valve needle (3) to reciprocate in the valve body (1); the valve needle (3) is provided with a conical sealing part matched with a valve port of the valve seat (4), the conical sealing part of the valve needle (3) and the valve port of the valve seat (4) form a matched conical sealing pair, a first coating (31) is arranged on the conical sealing part of the valve needle (3), a second coating (41) is arranged on the valve port surface of the valve seat (4), the first coating (31) and the second coating (41) are made of different materials to form a heterogeneous metal sealing pair, and the valve needle (3) and the valve seat (4) are of a paired matched grinding structure.
  2. 2. An electronic expansion valve with a sealing pair of dissimilar metals according to claim 1, wherein said first coating (31) is an antifriction coating and said second coating (41) is a wear-resistant hard coating.
  3. 3. An electronic expansion valve with a sealing pair of dissimilar metals according to claim 2, characterized in that said first coating (31) is a DLC coating and said second coating (41) is a CrN coating.
  4. 4. An electronic expansion valve with a heterogeneous metal sealing pair according to claim 3, characterized in that the thickness of the first coating (31) is 2-5 μm and the thickness of the second coating (41) is 3-5 μm.
  5. 5. The electronic expansion valve with the heterogeneous metal sealing pair according to claim 1, wherein the effective contact rate between the conical sealing part of the valve needle (3) and the valve port of the valve seat (4) is more than or equal to 98 percent.
  6. 6. The electronic expansion valve with the heterogeneous metal sealing pair according to claim 1, wherein the base body of the valve needle (3) is austenitic stainless steel, and the base body of the valve seat (4) is an austenitic stainless steel powder metallurgy sintered body.
  7. 7. The electronic expansion valve with the heterogeneous metal sealing pair according to claim 6, wherein the sintered density of the valve seat (4) is more than or equal to 7.0g/cm < 3 >.
  8. 8. An electronic expansion valve with a heterogeneous metal sealing pair according to claim 1, characterized in that the coaxiality between the valve needle (3) and the valve seat (4) is less than or equal to 0.01mm.

Description

Electronic expansion valve with heterogeneous metal sealing pair Technical Field The invention belongs to the technical field of electronic expansion valves, and particularly relates to an electronic expansion valve with a heterogeneous metal sealing pair. Background The electronic expansion valve is used as a key throttling element in a refrigeration and fluid control system and is widely applied to central air conditioners, heat pumps and various industrial oil way systems. In oil circuit applications, electronic expansion valves are required to operate for long periods of time in complex media environments with high differential pressure, high oil temperatures, and trace amounts of impurities. The existing electronic expansion valve special for the oil way mostly adopts an all-metal sealing structure so as to ensure medium compatibility. In this structure, the valve needle and the valve seat are usually machined from homogenous or heterogeneous metal materials, and the two materials form a sealing pair through conical surface matching. In order to ensure sealing performance, the metal sealing surface is often required to be hardened. However, under the working conditions of high-pressure closing force and high-frequency start-stop, micro welding or adhesive abrasion easily occurs to a homogeneous metal sealing pair (such as stainless steel to stainless steel) under the boundary lubrication condition, so that the valve needle is blocked or even bitten, and the reliability of system control is directly affected. Secondly, although the quenching process can improve the surface hardness, the heat treatment process is easy to cause the internal stress and microstructure change of the part matrix, and the dimensional stability and long-term fatigue resistance of the part are reduced. Therefore, for the electronic expansion valve special for the oil way, the wear resistance, the seizure resistance and the long-term structural stability of the sealing pair need to be improved so as to meet the requirement of long-term reliable operation. Disclosure of Invention The invention aims to overcome the defects, and provides the electronic expansion valve with the heterogeneous metal sealing pair, which realizes full metal sealing with high reliability and long service life through double-coating heterogeneous matching and paired mating and grinding processes. In order to achieve the above purpose, the invention provides an electronic expansion valve with a heterogeneous metal sealing pair, which comprises a valve body, a valve head arranged on the valve body, a valve needle arranged in the valve body in a reciprocating manner, and a valve seat fixed in the valve body and provided with a valve port. The valve head is in driving connection with the valve needle, and the valve head drives the valve needle to reciprocate in the valve body. The valve needle is provided with a conical sealing part matched with the valve port of the valve seat, and the conical sealing part of the valve needle forms a conical sealing pair matched with the valve port of the valve seat. The conical sealing part of the valve needle is provided with a first coating, the surface of the valve port of the valve seat is provided with a second coating, and the materials of the first coating and the second coating are different. The valve needle and the valve seat are of a paired matched grinding structure. The invention is used in a refrigeration and fluid control system to apply a control signal to a coil in a valve head when the control system needs to regulate flow. The rotor inside the valve head rotates under the action of an electromagnetic field, and the rotating motion is converted into linear reciprocating motion of the valve needle through a screw-nut mechanism. When the valve needle moves downwards, the conical sealing part at the lower end of the valve needle gradually approaches the valve port of the valve seat. When the valve needle moves to the lower limit position, the conical sealing part is tightly attached to the conical surface of the valve port to form a conical sealing pair, so that a fluid channel is cut off, and the shut-off function is realized. When the valve needle moves upward, the tapered seal disengages the valve port and the fluid passageway opens. The opening height of the valve needle determines the flow area of the valve port, thereby realizing accurate adjustment of flow. Because the conical sealing part of the valve needle is provided with the first coating, the valve port surface of the valve seat is provided with the second coating, and the materials of the first coating and the second coating are different, the phenomenon of cold welding of homogeneous metal is avoided when the valve needle and the valve seat are in hard sealing contact with each other. Meanwhile, the valve needle and the valve seat are matched and ground in pairs, so that the valve needle and the valve seat have high anastomosis degree, and the s