Expansion valve

Abstract

An expansion valve for a refrigerant cycle has an orifice passage portion, a valve body, a spring member and a deformation portion. The orifice passage portion is configured for decompressing and expanding a high pressure refrigerant into a low pressure refrigerant. The valve body is disposed to open and close the orifice passage portion so that a flow rate of the low pressure refrigerant flowing into a low pressure passage portion is controlled in accordance with a valve opening degree. The spring member is disposed between the valve body and the deformation portion for applying a biasing force to the valve body. The deformation portion is plastically deformable in a direction parallel to an expansion and contraction direction of the spring member by applying an external force.

Description

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is based on Japanese Patent Application No. 2006-259438 filed on Sep. 25, 2007, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to an expansion valve for a refrigerant cycle.

BACKGROUND OF THE INVENTION

[0003] An expansion valve for a refrigerant cycle generally controls a valve opening degree by detecting at least of temperature and pressure of a refrigerant, thereby to control the flow of the refrigerant in the refrigerant cycle. For example, a thermal-type expansion valve that controls a refrigerant to a predetermined condition by detecting the temperature and the pressure of low pressure-side refrigerant is generally known. Also, an expansion valve that controls the refrigerant by detecting a condition of high pressure-side refrigerant is generally known as a pressure control valve.

[0004] For example, Japanese Unexamined Patent Publication No. 2002-310538 (U.S. Pat. No. 6,560,982 B2) discloses a thermal-type expansion valve having a ball valve. In the disclosed expansion valve, a high pressure passage and a low pressure passage are offset in a longitudinal direction of a main body block and are communicated with each other through an orifice passage. Namely, the disclosed expansion valve has a crank-shaped refrigerant passage in the main body block. The orifice passage extends in the longitudinal direction, and an operation rod, which has a diameter smaller than an inner diameter of the orifice passage, is disposed in the orifice passage. The operation rod is provided with a ball valve at its end for controlling the orifice passage. Namely, as the operation rod is moved in the orifice passage in the longitudinal direction, the orifice passage is opened or closed by the ball valve.

[0005] The orifice passage is in communication with an opening formed at a top portion of the main body block. When the expansion valve is assembled, the operation rod with which the ball valve is integrated is inserted into the orifice passage from the opening of the main body block. Specifically, in a condition that a valve seating member is placed on a periphery of the operation rod, the ball valve is integrated with the end of the operation rod, such as by welding. Then, the operation rod with the valve seating member and the ball valve is inserted into the orifice passage. At this time, the valve seating member is press-fitted in the orifice passage by a large diameter portion of the operation rod.

[0006] In such an expansion valve in which an operation rod and other members are inserted through an opening of a main body block, the number of component parts is reduced and the component parts are easily assembled. Thus, it is easy to improve assembling accuracy. However, the length of the operation rod will be varied when the ball valve is welded. Also, the operation rod will be deformed when the valve seating member is press-fitted. If the above situations occur, it is difficult to maintain the characteristic of the valve opening degree within a predetermined characteristic range.

SUMMARY OF THE INVENTION

[0007] In an expansion valve, it is proposed to adjust the characteristic of the valve opening degree by using an adjustment mechanism before shipment. Further, an adjustment mechanism that enables simple adjustment of the characteristic of the valve opening degree without increasing costs and the number of component parts is desired.

[0008] The present invention is made in view of the foregoing matter, and it is an object of the present invention to provide an expansion valve in which a characteristic of a valve opening degree is adjustable by a simple structure.

[0009] According to an aspect of the present invention, an expansion valve for a refrigerant cycle has a high pressure passage portion through which a high pressure refrigerant flows, an orifice passage portion that is in communication with the high pressure passage portion, and a low pressure passage portion that is in communication with the orifice passage. The high pressure refrigerant flowing from the high pressure passage portion is decompressed and expanded into a low pressure refrigerant in the orifice passage, and the low pressure refrigerant flows into the low pressure passage portion. The expansion valve further has a valve body, a spring member and a deformation portion. The valve body is disposed to open and close the orifice passage such that a flow rate of the low pressure refrigerant flowing into the low pressure passage portion is controlled in accordance with an opening degree thereof. The spring member is disposed between the valve member and the deformation portion for applying a biasing force to the valve body. The deformation portion is plastically deformable in a direction parallel to an expansion and contraction direction of the spring member by an applied force.

[0010] The deformation portion is plastically deformed in the expansion and contraction direction of the spring member by applying an external force. By deforming the deformation portion such that a distance between the valve body and the deformation portion reduces, that is, in a contraction direction of the spring member, the biasing force of the spring member to the valve body increases. On the other hand, by deforming the deformation portion such that the distance between the valve body and the deformation portion increases, that is, in an expansion direction of the spring member, the biasing force of the spring member to the valve body reduces. Namely, by deforming the deformation portion in the expansion and contraction direction of the spring member, the biasing force of the spring member is adjusted. Therefore, the opening degree of the valve body is adjusted to have a predetermined characteristic. In this way, the characteristic of the valve opening degree is properly adjusted by such a simple structure.

[0011] For example, the deformation portion is integrally formed into a main body block that houses the spring member therein. Namely, the deformation portion is formed at the same time as the main body block is formed. Alternatively, the deformation portion is provided by a deformation plate member, which is separately formed from a main body block. The deformation plate member is fixed in an opening portion of the main body block, and is deformed so that the spring member has a predetermined biasing force.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings, in which like parts are designated by like reference numbers and in which:

[0013] FIG. 1 is a schematic cross-sectional view of a thermal-type expansion valve for a refrigerant cycle according to a first embodiment of the present invention;

[0014] FIG. 2 is an enlarged cross-sectional view of a part of the expansion valve according to the first embodiment;

[0015] FIG. 3 is a graph showing a relationship between the amount of movement of an adjustment jig and the amount of change of a set value according to the first embodiment;

[0016] FIG. 4 is an enlarged cross-sectional view of a part of an expansion valve having a tubular projection according to a second embodiment of the present invention;

[0017] FIG. 5 is an enlarged cross-sectional view of a part of an expansion valve having a peripheral wall with a female thread according to a third embodiment of the present invention;

[0018] FIG. 6 is an enlarged cross-sectional view of a part of an expansion valve having a deformable plate as a deformation portion according to a fourth embodiment of the present invention; and

[0019] FIG. 7 is a schematic cross-sectional view of an expansion valve having a ball valve according to a fifth embodiment of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0020] A first embodiment of the present invention will now be described with reference to FIGS. 1 to 3. FIG. 1 shows an example of a thermal-type expansion valve 1 (hereafter, simply referred to as the expansion valve 1). The expansion valve 1 is generally employed in a refrigerant cycle for decompressing and expanding a liquid-phase, high pressure refrigerant, which flows out from a condenser 2, into a low pressure refrigerant and introducing the low pressure refrigerant into an evaporator 3. Also, the expansion valve 1 adjusts an opening degree of a valve thereof in accordance with a degree of superheat of the refrigerant that flows out from the evaporator 3, thereby to control a flow rate of the low pressure refrigerant to be introduced into the evaporator 3.

[0021] In the refrigerant cycle, the refrigerant flows in the following manner. First, a high pressure refrigerant that has been compressed in a compressor 4 passes through the condenser 2. While passing through the condenser 2, the high pressure refrigerant becomes the liquid-phase, high pressure refrigerant due to heat exchange.

[0022] Then, the liquid-phase, high pressure refrigerant is decompressed and expanded in the expansion valve 1 and becomes a gas and liquid two-phase, low pressure refrigerant. Thereafter, the two-phase, low pressure refrigerant becomes a gas-phase, low pressure refrigerant in the evaporator 3 due to heat exchange, and then the gas-phase, low pressure refrigerant is drawn into the compressor 4.

[0023] The expansion valve 1 generally has a main body block 100 and a power element 400. The main body block 100 includes a superheat detection passage 200 and a decompression passage 300. Each of the superheat detection passage 200 and the decompression passage 300 extends through the main body block 100 in a direction generally perpendicular to a longitudinal direction of the main body block 100. The superheat detection passage 200 and the decompression passage 300 are aligned with each other in a longitudinal direction of the main body block 100.

[0024] In the superheat detection passage 200, which is located above the decompression passage 300 in FIG. 1, the gas-phase, low pressure refrigerant flowing from the evaporator 3 flows toward the compressor 4. The superheat detection passage 200 is provided to detect the degree of superheat of the gas-phase, low pressure refrigerant flowing therein.

[0025] In the decompression passage 300, the liquid-phase, high pressure refrigerant, which has flowed from the condenser 2, flows. The decompression passage 300 is provided to decompress and expand the liquid-phase, high pressure refrigerant into the low pressure refrigerant, and discharge the low pressure refrigerant toward the evaporator 3.

[0026] The main body block 100 has an opening 110 on an end adjacent to the superheat detection passage 200. The opening 110 is in communication with the superheat detection passage 200. The power element 400 is mounted to the opening 110. The power element 400 is configured to control the valve opening degree of a spool valve 600 as a valve body in accordance with the degree of superheat detected in the superheat detection passage 200.

[0027] The power element 400 generally has a case 410 and a diaphragm 420. The diaphragm 420 is housed in the case 410 such that an inner space of the case 410 is divided into two chambers in the longitudinal direction of the main body block 100. One of the chambers, which is adjacent to the main body block 100, is referred to as a lower pressure chamber 440, and the other chamber, which is farther away than the lower pressure chamber 440 with respect to the main body block 100, is referred to as an upper pressure chamber 430.

[0028] The upper pressure chamber 430 is filled with a saturated refrigerant and is sealed by a plug 431. The temperature of the refrigerant passing through the superheat detection passage 200 is detected by the refrigerant in the first pressure chamber 430, and a saturation pressure according to the detected temperature is exerted to the diaphragm 420. In the lower pressure chamber 440, a stopper member 441 is housed in a condition that an outer peripheral portion thereof is interposed between the case 410 and the diaphragm 420.

[0029] The case 410 has a tubular part at its lower end. A male thread portion 411 is formed on an outer surface of the tubular part. The male thread portion 411 engages a female thread portion 111 that is formed on a wall defining the opening 110 of the main body block 100.

[0030] The tubular part of the case 410 has an opening 412. The case 410 is arranged on the main body block 100 such that the opening 412 of the case 410 is in communication with the opening 110 of the main body block 100. Thus, the refrigerant passing through the superheat detection passage 200 can reach the stopper member 441 through the openings 110, 412. Namely, the stopper member 441 can receive the pressure of the refrigerant passing through the superheat detection passage 200.

[0031] Accordingly, the saturation pressure of the refrigerant of the upper pressure chamber 430 and the refrigerant pressure applied to the stopper member 441 are exerted to the diaphragm 420. Thus, the diaphragm 420 moves up and down, that is, in the longitudinal direction of the main body block 100 in response to the difference between the saturation pressure and the refrigerant pressure. The position of the stopper member 441 is determined by the movement of the diaphragm 420.

[0032] Thus, when the difference between the saturation pressure and the refrigerant pressure increases, the stopper member 441 moves downward, that is, toward the main body block 100. On the other hand, when the difference reduces, the stopper member 441 moves upward, that is, in a direction opposite to the main body block 100. As a result, when the degree of superheat increases, the stopper member 441 moves downward. When the degree of superheat reduces, the stopper member 441 moves upward.

[0033] An operation rod 450 is coupled to the stopper member 441 for transmitting the movement of the stopper member 441 to the spool valve 600 that is disposed in the decompression passage 300. The operation rod 450 extends across the superheat detection passage 200 and connects to the spool valve 600. The operation rod 450 is movable with the movement of the stopper member 441. Thus, the operation rod 450 applies a biasing force to the spool valve 600 in a downward direction, that is, in a valve opening direction.

[0034] The decompression passage 300 includes a high pressure passage portion 310, a low pressure passage portion 320, and a small diameter passage portion 330 as a communication passage portion. The high pressure passage portion 310 and the low pressure passage portion 320 are offset from each other in the longitudinal direction of the main body block 100. The high pressure passage portion 310 and the low pressure passage portion 320 are communicated with each other through the small diameter passage portion 330 that extends in the longitudinal direction of the main body block 100.

[0035] The high pressure passage portion 310 is provided to allow the liquid-phase, high pressure refrigerant flowing from the condenser 2 to flow into the small diameter passage portion 330. In the small diameter passage portion 330, the high pressure, liquid-phase refrigerant is decompressed and expanded. The low pressure passage portion 320 is located at a position higher than the high pressure passage portion 310. The low pressure passage portion 320 is provided to allow the low pressure refrigerant flowing from the small diameter passage portion 330 to flow toward the evaporator 3.

[0036] The spool valve 600 is disposed in the small diameter passage portion 330. Also, a spring member 700 is disposed in the small diameter passage portion 330 for applying a force to the spool valve 600 in the upward direction. In the example shown in FIG. 1, the upward direction corresponds to a valve closing direction for closing the valve, and the downward direction corresponds to the valve opening direction for opening the valve. The upward and downward direction, that is, the longitudinal direction of the main body block 11 corresponds to an expansion and contraction direction of the spring member 700.

[0037] In this embodiment, the spring member 700 is disposed in the small diameter passage portion 330 in an compressed condition, that is, in a pre-stressed condition. Here, the valve closing direction corresponds to the expansion direction of the spring member 700. The valve opening direction corresponds to the contraction direction of the spring member 700. An outer diameter of the spool valve 600 and an outer diameter of the spring member 700 are substantially equal to an inner diameter of the small diameter passage portion 330.

[0038] The spool valve 600 is formed with an orifice passage 610. The orifice passage 610 has a substantially T-shape and allows communication between the high pressure passage portion 310 and the low pressure passage portion 320. The orifice passage 610 is provided to decompress and expand the high pressure, liquid-phase refrigerant flowing from the high pressure passage portion 310 therein and discharge the decompressed and expanded low pressure refrigerant into the low pressure passage portion 320. Also, the spool valve 600 is formed with an outer peripheral groove 620 on a periphery of a top portion (refrigerant discharge portion) 611 of the T-shaped orifice passage 610.

[0039] The spool valve 600 is movable in the small diameter passage 330 in the upward and downward direction. As the spool valve 600 moves in the upward and downward direction, a communication area between the outer peripheral groove 620 and the low pressure passage 320 varies. By this mechanism, the amount of the low pressure refrigerant flowing into the low pressure passage portion 320 is controlled.

[0040] Namely, when the spool valve 610 is moved in the valve opening direction, that is, in the downward direction, the communication area between the outer peripheral groove 620 and the low pressure passage 320 is increased. That is, the valve opening degree is increased. As such, the amount of the low pressure refrigerant flowing into the low pressure passage portion 320 increases.

[0041] On the other hand, when the spool valve 610 is moved in the valve closing direction, that is, in the upward direction, the communication area is reduced. That is, the valve opening degree is reduced. As such, the amount of the low pressure refrigerant flowing into the low pressure passage portion 320 reduces. Accordingly, the amount of the low pressure refrigerant flowing into the low pressure passage portion 320 is controlled by controlling the valve opening degree of the spool valve 600.

[0042] The spring member 700 is disposed under the spool valve 600 in the small diameter passage portion 330 for applying the force to the spool valve 600 in the upward direction. The spring member 700 is, for example, a coil spring. Further, in the small diameter passage portion 330, a spring seating member 710 is disposed at the lower end of the spring member 700. The spring seating member 710 is provided to improve the stability of the spring member 700 and to restrict the main body block 110 from being cut or damaged by rotation of the spring member 700.

[0043] The main body block 100 has a deformation portion 120 at a lower position of the small diameter passage portion 330. The deformation portion 120 is plastically deformable in the upward direction, that is, in the valve closing direction by an external force. The deformation portion 120 is a thin wall that is thinner than a peripheral portion thereof in the main body block 100 with respect to the upward and downward direction, that is, in the valve opening and closing direction.

[0044] The spring member 700 is disposed between the spool valve 600 and the deformation portion 120. Thus, the deformation portion 120 serves as a seating for receiving a load from the spring member 700. The deformation portion 120 has predetermined thickness and size (e.g., area) such that the deformation portion 120 is displaceable in the upward and downward direction, that is, in a direction parallel to the expansion and contraction direction of the spring member 700. Also, the deformation portion 120 is displaceable in such a range that an initial load, such as a pre-stress, applied to the spring member 700 can be changed.

[0045] Further, the deformation portion 120 is displaceable in such a range that the characteristic of the expansion valve 1 is adjusted in a manufacturing process. The deformation portion 120 is formed at a position where an adjustment jig 800 as a tool for the deformation can easily reach in a condition that the main block body 100 is securely held. The deformation portion 120 is much thinner than the peripheral portion thereof in the main body block 100.

[0046] The main body block 100 has a substantially polyhedral shape. The deformation portion 120 is located in a recess that is formed at a substantially middle portion of one of sides of the polyhedral shape. For example, the deformation portion 120 is located in the recess that is formed on the bottom wall of the main body block 100. The recess is defined by a peripheral wall 130 and an outer surface of the deformation portion 120.

[0047] An inner surface of the deformation portion 120, that is, an upper surface of the deformation portion 120 serves as a receiving surface 120A that receives a load from the spring member 700. In other words, the receiving surface 120A serves to apply the force of the spring member 700 toward the spool valve 600. The outer surface of the deformation portion 120, that is, a lower surface of the deformation portion 120 serves as a working surface 120B that receives the external force by the adjustment jig 800 such as a plunger. Each of the receiving surface 120A and the working surface 120B has a circular shape, for example.

[0048] The peripheral wall 130 is coaxial with the deformation portion 120. The diameter of the peripheral wall 130 is larger than an outer diameter of the receiving surface 120A. Namely, the working surface 120B is relatively larger than the receiving surface 120A.

[0049] The above described expansion valve 1 is assembled in the following manner. First, the spring seating member 710, the spring member 700, and the spool valve 600 are placed in the small diameter passage portion 330 through the opening 100 in this order. Then, the power element 400 is screwed into the opening 110 of the main body block 100.

[0050] After the component parts are assembled in the above manner, the deformation portion 120 is deformed so as to adjust a control characteristic of the spool valve 600. In the first embodiment, this adjustment step is performed after all the component parts associated with a movable section of the expansion valve 1 are assembled.

[0051] In the expansion valve 1, the valve opening degree of the spool valve 600 is controlled in the following manner. When the degree of the superheat of the refrigerant flowing from the evaporator 3 increases, the pressure difference in the power element 400 increases. As such, the operation rod 450 is urged in the downward direction by the stopper member 441. Namely, the operation rod 450 biases the spool valve 600 in the downward direction.

[0052] Therefore, the spool valve 600 moved in the downward direction in the small diameter passage portion 330 against the spring member 700. As a result, the communication area between the low pressure passage portion 320 and the outer peripheral groove 620 of the orifice passage 610 increases. That is, the valve opening degree increases. Therefore, the amount of the low pressure refrigerant flowing into the low pressure passage portion 320 increases.

[0053] On the other hand, when the degree of superheat of the refrigerant flowing out from the evaporator 3 reduces, the pressure difference in the power element 400 reduces. As such, the operation rod 450 is urged in the upward direction with the stopper member 441. Therefore, the biasing force for biasing the spool valve 600 in the downward direction is reduced. As a result, the spool valve 600 is moved in the upward direction in the small diameter passage portion 330 by the force of the spring member 700. With this, the communication area between the low pressure passage portion 320 and the outer peripheral groove 620, that is, the valve opening degree reduces. Therefore, the amount of the low pressure refrigerant flowing into the low pressure passage portion 320 reduces.

[0054] In this embodiment, spring-back force (biasing force) of the spring member 700 is adjusted such that the characteristic of the valve opening degree is in a predetermined characteristic range. The adjustment of the biasing force of the spring member 700 is performed by plastically deforming the deformation portion 120 in the upward direction using the adjustment jig 800.

[0055] First, the adjustment jig 800 is aligned with the working surface 120B of the deformation portion 120. At this time, because the adjustment jig 800 is inserted within the peripheral wall 130, the adjustment jig 800 is properly positioned with respect to the deformation portion 120.

[0056] In a condition that the adjustment jig 800 is in contact with the working surface 120B of the deformation portion 120, the adjustment jig 800 is moved in the upward direction. As such, the deformation portion 120 is deformed in the upward direction by the force generated by the adjustment jig 800, and thus the receiving surface 120A is moved upward. Since the working surface 120B is relatively larger than the receiving surface 120A, the deformation of the deformation portion 120 is exerted entirely over the receiving surface 120A. Thus, the receiving surface 120A is entirely moved in the upward direction.

[0057] As a result, a distance between the receiving surface 120A and the spool valve 600 is reduced. Thus, the biasing force of the spring member 700 for biasing the spool valve 600 in the valve closing direction is adjusted to increase. In this way, the characteristic of the valve opening degree of the spool valve 600 is adjusted.

[0058] Here, the characteristic of the spring member 700 to be set is predetermined. Also, the amount of movement of the receiving surface 120A, which is required to set the characteristic, is predetermined. Therefore, in the adjustment step, the adjustment jig 800 is moved by a predetermined amount in accordance with the predetermined amount of movement of the receiving surface 120A.

[0059] For example, a thickness t1 of the deformation portion 120 is 1 mm, and a diameter .phi. of the deformation portion 120 is 14 mm. FIG. 3 shows a relationship between the amount of movement of the adjustment jig 800 and the amount of change of a set value (initial spring-back force) of the spring member 700 for the deformation portion 120 having the above thickness and diameter.

[0060] As shown in FIG. 3, when the amount of movement of the adjustment jig 800 is smaller than 0.8 mm, the amount of change of the set value is substantially in proportion to the amount of movement. Therefore, when the set value needs to be changed in a range between 0 and 40 kPa, the adjustment jig 800 is moved by the corresponding amount.

[0061] The thickness t1 and the diameter .phi. of the deformation portion 120 are not limited to the above values, but may be varied in a thickness range between 0.5 mm and 2 mm and in a diameter range between 7 mm and 20 mm, respectively. In these thickness range and diameter range, the movement of the adjustment jig 800 and the set value have the similar relationship as the relationship shown in FIG. 3.

[0062] When the thickness t1 is larger than 2 mm, that is, when the thickness t1 is large relative to the diameter .phi., the deformation portion 120 does not substantially deform even if the amount of movement of the adjustment jig 800 is increased. In this case, therefore, it is difficult to adjust the set value of the spring member 700 to a desired set value.

[0063] On the other hand, when the thickness t1 is smaller than 0.5 mm, that is, when the thickness t1 is small relative to the diameter .phi., rigidity of the deformation portion 120 reduces. Therefore, even when the deformation portion 120 is deformed by the adjustment jig 800, the deformation portion 120 is likely to be pushed back in the downward direction due to such as the biasing force of the spring member 700 and the pressure of the refrigerant in the small diameter passage portion 330. As such, even when the deformation portion 120 is deformed by the predetermined amount, it is difficult to maintain the set value in a desired set value.

[0064] When the thickness t1 and the diameter .phi. of the deformation portion 120 are in the above ranges, the set value of the spring member 700 is appropriately set in accordance with the amount of movement of the adjustment jig 800.

[0065] As described above, the biasing force of the spring member 700 in the valve closing direction is increased by deforming the deformation portion 120 in the upward direction using the adjustment jig 800. Since the biasing force of the spring member 700 is adjusted by the deformation of the deformation portion 120, the characteristic of the valve opening degree is adjusted to the predetermined characteristic.

[0066] Further, since the set value of the spring member 700 is adjusted by deforming the deformation portion 120, a structure required for adjusting the set value is simplified. Also, even by the simple structure, the adjustment of the set value is appropriately performed.

[0067] The deformation portion 120 is provided by the thin wall portion of the main body block 100. Namely, it is not necessary to provide the deformation portion 120 separately. As such, the structure is further simplified.

[0068] Also, since the working surface 120B is relatively larger than the receiving surface 120A, the receiving surface 120A is entirely deformed in the upward direction. That is, it is less likely that the receiving surface 120A will be partly deformed.

[0069] The main body block 100 has the peripheral wall 130 that is coaxial with the deformation portion 120. Therefore, the adjustment jig 800 is easily and properly positioned with respect to the deformation portion 120. Accordingly, the deformation portion 120 is properly deformed.

Second Embodiment

[0070] A second embodiment will be described with reference to FIG. 4. In this embodiment, the deformation portion 120 is formed on the bottom wall of the main body block 100. The working surface 120B is provided by a portion of the bottom surface of the main body block 100. The main body block 100 has a tubular projection 140 that extends from the working surface 120B. The tubular projection 140 has a female thread portion 140A on its inner surface, so that the adjustment jig 800 is screwed into the tubular projection 140. The tubular projection 140 is integrally formed with the main body block 100 when the main body block 100 is formed.

[0071] The tubular projection 140 serves an operation portion for displacing the deformation portion 120 in at least one of the upward direction and the downward direction. For example, the tubular projection 140 is located at a center of the deformation portion 120. The tubular projection 140 extends in a direction parallel to the displacement direction of the deformation portion 120. The deformation portion 120 can be displaced in one of or both of the expansion direction and the contraction direction of the spring member 700.

[0072] The adjustment jig 800 is formed with a male thread portion 800A on its outer surface so that the adjustment jig 800 is screwed with the female thread portion 140A of the tubular projection 140. In a condition that the adjustment jig 800 is engaged with the tubular projection 140, the adjustment jig 800 is moved in at least one of the upward direction and the downward direction.

[0073] When the adjustment jig 800 is moved upward, the deformation portion 120 deforms in the upward direction. Thus, the receiving surface 120A moves in the upward direction. On the other hand, when the adjustment jig 800 is moved downward, the deformation portion 120 deforms in the downward direction. Thus, the receiving surface 120A moves in the downward direction.

[0074] Accordingly, since the receiving surface 120A can be deformed in both of the upward direction and the downward direction, the biasing force of the spring member 700 is adjusted in both direction, that is, adjusted in an increase manner and a decrease manner.

Third Embodiment

[0075] A third embodiment of the present invention will be described with reference to FIG. 5. In this embodiment, the main body block 100 has the recessed portion on its bottom, and the deformation portion 120 is provided by the wall that defines the recessed portion. As shown in FIG. 5, the peripheral wall 130 is formed with a female thread portion 130A to which the male thread portion 800A of the adjustment jig 800 is screwed.

[0076] Here, the depth of the recessed portion is greater than that of the first embodiment. Further, the depth of the recessed portion is greater than the diameter of the deformation portion 120.

[0077] The deformation portion 120 is deformed in the upward direction by screwing the adjustment jig 800 into the recessed portion. In this case, the deformation portion 120 can be deformed by a force that is smaller than the force required to simply moving the adjustment jig 800 as the first embodiment. As such, the deformation portion 120 is easily deformed by a small device without requiring a large apparatus such as a pressing machine.

Fourth Embodiment

[0078] A fourth embodiment will be described with reference to FIG. 6. As shown in FIG. 6, the main body block 100 is formed with an opening portion 150 on its bottom end. The opening portion 150 is located at the bottom of the small diameter passage portion 330 and is in communication with the small diameter passage portion 330. The opening portion 150 is coaxial with the small diameter passage portion 330 and has an inner diameter larger than the inner diameter of the small diameter passage portion 330. Namely, the opening portion 150 is formed at a position opposite to the spool valve 600 and the inner diameter of the opening portion 150 is larger than the outer diameter of the spring member 700.

[0079] Further, a deformation plate member 160 having a shape corresponding to an inner shape of the opening portion 150 is fixed in the opening portion 150 such as in a pressed manner. For example, the deformation plate member 160 has a substantially cup shape. The deformation plate member 160 is fixed to the main body block 100 such that an opening of the cup-shaped deformation plate member 160 faces the spring member 700.

[0080] Namely, the opening portion 150 is formed as the recessed portion, and the deformation plate member 160 is fixed in the recessed portion. Thus, the deformation plate member 160 serves as the deformation portion 120. Accordingly, the set value of the spring member 700 is adjusted by deforming the deformation plate member 160 using the adjustment jig 800. As such, the characteristic of the valve opening degree is adjusted.

[0081] In this structure, it is easy to increase the diameter of the deformation plate member 160. Thus, this structure is adaptable to increase the amount of deformation, that is, to increase the adjustment range.

Fifth Embodiment

[0082] A fifth embodiment will be described with reference to FIG. 7. In the fifth embodiment, the expansion valve 1 has a ball valve 900 in place of the spool valve 600. Hereafter, structures different from the above embodiments will be mainly described.

[0083] As shown in FIG. 7, a first valve seating member 910 is disposed above the spring member 700 within the small diameter passage portion 330 for supporting the ball valve 900. Also, a second valve seating member 920 is disposed above the first valve seating member 910 in the small diameter passage portion 330, such as in a pressed manner.

[0084] The second valve seating member 920 is formed with a through hole 921. The through hole 921 extends in the axial direction of the small diameter passage portion 330. The operation rod 450 passes through the through hole 921 and contacts the ball valve 900, which is disposed between the first valve seating member 910 and the second valve seating member 920. The second valve seating member 920 is further formed with a communication opening 922 that extends perpendicular to the through hole 921. The communication opening 922 is disposed to communicate with the low pressure passage portion 320.

[0085] A lower area of the through hole 921, which allows communication between the high pressure passage portion 310 and the communication opening 922, provides an orifice passage 921A for decompressing and expanding the high pressure refrigerant. The ball valve 900 is configured to open and close an inlet opening of the orifice passage 921A. Namely, the flow rate of the low pressure refrigerant flowing into the low pressure refrigerant passage 320 is adjusted by controlling an opening degree of the inlet opening of the orifice passage 921A by the ball valve 900.

[0086] Also in this embodiment, the main body block 100 is formed with the deformation portion 120 and the peripheral wall 130 at the bottom of the small diameter passage portion 330, similar to the first embodiment. As such, the characteristic of the valve opening degree is adjusted in the similar manner as the first embodiment. Alternatively, the deformation portion 120 and the peripheral wall 130 can be provided in the similar manner as one of the second to fourth embodiments.

Other Embodiments

[0087] The various exemplary embodiments of the present invention are described hereinabove. However, the present invention is not limited to the above described exemplary embodiments, but may be implemented in various other ways without departing from the spirit of the invention.

[0088] For example, the above embodiments will be modified in the following manners. In the first embodiment, the peripheral wall 130 is formed coaxially with the deformation portion 120. However, the peripheral wall 130 may be eliminated. That is, the working surface 120B may be formed to be aligned with the bottom wall of the main body block 100.

[0089] In the first embodiment, the working surface 120B is relatively larger than the receiving surface 120A. Alternatively, the working surface 120B may be the same size as the receiving surface 120A or be smaller than the receiving surface 120A.

[0090] In the first embodiment, the deformation portion 120 is deformed by moving the adjustment jig 800 such as by the pressing device. However, the deformation portion 120 may be deformed by other means. For example, the deformation portion 120 can be deformed by hitting with another tool such as a hammer.

[0091] In the second embodiment, the inner diameter of the tubular projection 140 is smaller than the inner diameter of the small diameter passage portion 330. Alternatively, the inner diameter of the tubular projection 140 may be the same as the inner diameter of the small diameter passage portion 330. In this case, the deformation portion 120 is entirely deformed in the upward and downward direction.

[0092] In the fourth embodiment, the inner diameter of the opening portion 150 is larger than the inner diameter of the small diameter passage portion 330. Alternatively, the inner diameter of the opening portion 150 may be the same as or smaller than the inner diameter of the small diameter passage portion 330.

[0093] In the above embodiments, the expansion valve 1 is configured such that the valve opening degree is controlled by detecting the condition of the low pressure refrigerant using the valve operation device such as the power element 400. However, the present invention may be employed to an expansion valve that controls a valve opening degree based on a condition of high pressure refrigerant detected by a valve operation device. Further, the present invention may be implemented by combining the above embodiments in various ways.

Claims

1. An expansion valve for a refrigerant cycle, comprising: a high pressure passage portion that allows a high pressure refrigerant to flow; an orifice passage portion disposed to communicate with the high pressure passage portion for decompressing and expanding the high pressure refrigerant, which flows from the high pressure passage portion, into a low pressure refrigerant; a low pressure passage portion disposed to communicate with the orifice passage portion for allowing the low pressure refrigerant to flow; a valve body disposed to open and close the orifice passage portion such that a flow rate of the low pressure refrigerant flowing into the low pressure passage portion is controlled in accordance with an opening degree of the valve body; a spring member disposed to apply a biasing force to the valve body; and a deformation portion disposed on an opposite side of the valve body with respect to the spring member such that the spring member is interposed between the deformation portion and the valve body, wherein the deformation portion is plastically deformable in a direction parallel to an expansion and contraction direction of the spring member by an external force.

2. The expansion valve according to claim 1, further comprising: a main body block, wherein the spring member is housed in the main body block, and the deformation portion is provided by a wall of the main body block, the wall having a thickness that is smaller than a thickness of a peripheral area thereof in the main body block with respect to the direction parallel to the expansion and contraction direction of the spring member.

3. The expansion valve according to claim 1, further comprising: a main body block that houses the spring member therein, the main body block having an opening portion at a position opposite to the valve body; and a deformation plate member having a shape corresponding to the opening portion, wherein the deformation plate member is disposed in the opening portion and fixed to the main body block, and the deformation portion is provided by the deformation plate member.

4. The expansion valve according to claim 3, wherein the opening portion has an inner diameter that is greater than an outer diameter of the spring member, the outer diameter of the spring member being defined in a direction perpendicular to the expansion and contraction direction of the spring member.

5. The expansion valve according to claim 1, wherein the deformation portion has a first surface to which the external force is applied and a second surface that receives the spring member, and an area of the first surface is equal to or greater than that of the second surface.

6. The expansion valve according to claim 5, wherein the thickness of the deformation portion is at least 0.5 mm and at most 2 mm, and the second surface has an outer diameter that is at least 7 mm and at most 20 mm.

7. The expansion valve according to claim 5, wherein the main body block has a peripheral wall portion that coaxially extends from the first surface of the wall.

8. The expansion valve according to claim 7, wherein the peripheral wall portion has a thread portion so that an adjustment jig for applying the external force is capable of being screwed into the peripheral wall portion.

9. The expansion valve according to claim 2, wherein the main body block has a tubular projection projecting from the deformation portion, and the tubular projection includes a thread portion so that an adjustment jig for applying the eternal force is capable of being screwed into the tubular projection.

10. An expansion valve for a refrigerant cycle, comprising: a main body block having a high pressure passage portion, a low pressure passage portion and a communication passage portion between the high pressure passage portion and the low pressure passage portion; a valve element disposed in the communication passage portion so that an orifice passage is defined for decompressing and expanding a high pressure refrigerant, which flows from the high pressure passage portion, into a low pressure refrigerant and for controlling a flow rate of the low pressure refrigerant flowing into the low pressure passage portion in accordance with an opening degree of the orifice passage; a spring member disposed in the communication passage portion for applying a biasing force to the valve element; and a deformation portion disposed on a side opposite to the valve element with respect to the spring member to define an end of the communication passage portion, wherein the spring member is disposed between the valve element and the deformation portion and a set value of the spring member is adjusted by deforming the deformation portion by a predetermined amount in a direction parallel to an expansion and contraction direction of the spring member.

11. The expansion valve according to claim 10, wherein the deformation portion is integrally formed into the main body block, and has a predetermined thickness in the direction parallel to the expansion and contraction direction of the spring member.

12. The expansion valve according to claim 10, wherein the main body block has a recessed portion on its outer wall and at a position opposite to the communication passage portion with respect to the deformation portion for receiving an adjustment jig when the deformation portion is deformed.