JP2018025364A - Expansion valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an expansion valve that has a simple structure and can prevent noise from being generated.SOLUTION: In an expansion valve 1, a shaft 5 that operates a valve part in order to adjust an amount of a refrigerant flowing through the valve part is arranged in a refrigerant passage 3 through which the refrigerant flows. An eigenvalue F0 of the refrigerant passage 3 in which the shaft 5 is arranged is set to be larger than a frequency F1 of a Karman vortex generated by an outside diameter D4 of the shaft 5. An outside shape of the shaft 5 is formed in a cylindrical shape, and the shaft 5 is arranged in an exposed state in the refrigerant passage 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an expansion valve and, for example, relates to an apparatus that adjusts the amount of refrigerant flowing to an evaporator according to the temperature and pressure of the refrigerant flowing from the evaporator.

  Conventionally, it is used in the refrigeration cycle of automobile air conditioners, and the high-temperature and high-pressure liquid refrigerant is decompressed and expanded to form a low-temperature and low-pressure mist-like refrigerant, and the evaporation state of the refrigerant at the evaporator outlet has an appropriate degree of superheat. An expansion valve 101 having a function of adjusting the flow rate of the refrigerant so as to have it is known (see FIG. 10).

  The side of the main body block 103 of the expansion valve 101 is decompressed and expanded by the expansion valve 101 and a port T1 to which a high-pressure refrigerant pipe is connected so as to receive a high-temperature and high-pressure refrigerant from a receiver / dryer (not shown). To a port T2 to which a low-pressure refrigerant pipe for supplying a low-temperature and low-pressure refrigerant to an evaporator (not shown) is connected, to a port T3 to which a refrigerant pipe from the evaporator outlet is connected, and to a compressor (not shown) And a port T4 to which the leading refrigerant pipe is connected.

  The port T1 and the port T2 are connected to each other by a refrigerant passage 105 provided in the main body block 103, and the port T3 and the port T4 are connected to each other by a refrigerant passage 107 provided in the main body block 102.

  A valve portion 109 for adjusting the opening degree of the refrigerant passage 105 (adjusting the flow rate of the refrigerant flowing through the refrigerant passage 105) is provided in the middle of the refrigerant passage 105.

  The valve portion 109 includes a valve seat 111 formed on the main body block 103 and a ball-shaped (spherical) valve body 113. The valve body 113 is disposed upstream of the valve seat 111 in the flow direction of the refrigerant flowing through the refrigerant passage 105.

  When the refrigerant passage 105 is closed, the valve body 113 moves upward from the state shown in FIG. 10, and the valve body 113 is in close contact with the valve seat 111. When the refrigerant passage 105 is closed, a gap 115 is formed between the valve seat 111 and the valve body 113 as shown in FIG. The gap 115 constitutes a variable orifice that throttles the high-pressure refrigerant.

  A compression coil spring 117 that urges the valve body 113 so that the valve body 113 is seated on the valve seat 111 is disposed in a space upstream of the valve seat 111.

  A power element 119 is provided at the upper end of the main body block 103. The power element 119 has a diaphragm 121 made of a flexible metal thin plate arranged so as to partition a space surrounded by a thick metal housing, and the lower surface thereof receives the displacement of the diaphragm 121. A diaphragm receiving plate 123 is disposed. The upper space of the diaphragm 121 constitutes a greenhouse, and is filled with two or more kinds of refrigerant gas and inert gas.

  A rod 125 that transmits the displacement of the diaphragm 121 to the valve body 113 is disposed below the diaphragm receiving plate 123. The rod 125 is supported by the main body block 103 and can move by a predetermined stroke in the vertical direction of FIG. 10, and also hangs down across the refrigerant passage 107 communicating with the ports T3 and T4. . Note that what is indicated by reference numeral 127 in FIG. 10 is a cover of the rod 125.

  The rod 125 has an upper end in contact with the lower surface of the diaphragm receiving plate 123 and a lower end in contact with the valve body 113. Thereby, the movement of the diaphragm 121 is transmitted to the valve body 113 through the diaphragm receiving plate 123 and the rod 125.

  In the expansion valve 101, when the temperature of the refrigerant returned from the evaporator to the port T <b> 3 decreases, the temperature of the temperature sensing chamber of the power element 119 decreases, and the refrigerant gas in the temperature sensing chamber condenses on the inner surface of the diaphragm 121. As a result, the pressure in the power element 119 is reduced and the diaphragm 121 is displaced upward, and the rod 125 is pushed by the compression coil spring 117 and moved upward. As a result, the valve body 113 moves to the valve seat 111 side, the passage area of the high-pressure refrigerant (passage area in the gap 115) is reduced, and the flow rate of the refrigerant sent to the evaporator is reduced. This also works in the same way when the pressure of the refrigerant returning from the evaporator to the port T3 increases.

  On the other hand, when the temperature of the refrigerant returned from the evaporator to the port T3 rises, the pressure in the temperature sensing chamber of the power element 119 rises, so that the rod 125 is pushed down against the urging force of the compression coil spring 117. Therefore, the valve body 113 moves in a direction away from the valve seat 111, the passage area of the high-pressure refrigerant is increased, and the flow rate of the refrigerant sent to the evaporator is increased. This also works in the same way when the pressure of the refrigerant returning from the evaporator to the port T3 decreases.

  For example, the one described in Patent Document 1 is known as a cover in which the cover 127 is removed from the above-described conventional expansion valve.

JP 2016-44861 A

  By the way, in the conventional expansion valve shown in FIG. 10, there exists a problem that the number of components will increase by providing a cover, and a structure will become complicated.

  When the conventional expansion valve shown in FIG. 10 is removed from the cover, there is a problem that noise may be generated due to Karman vortices generated by the refrigerant flowing through the shaft.

  Further, in the expansion valve described in Patent Document 1, dimple processing is performed on the shaft in order to reduce noise, but this causes a problem that the structure becomes complicated.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an expansion valve that can prevent the generation of noise with a simple configuration.

  The present invention relates to an expansion valve in which a shaft for operating the valve unit to adjust the amount of refrigerant flowing through the valve unit is arranged in a refrigerant passage through which the refrigerant flows, and the refrigerant in which the shaft is arranged The eigenvalue of the passage is set to be larger than the frequency of Karman vortex generated by the outer diameter of the shaft, the outer shape of the shaft is formed in a cylindrical shape, and the shaft is exposed in the refrigerant passage. It is the expansion valve which is arranged.

  According to the present invention, it is possible to provide an expansion valve capable of preventing the generation of noise with a simple configuration.

It is a figure which shows schematic structure of the expansion valve which concerns on embodiment of this invention. It is the figure which showed typically the expansion valve which concerns on embodiment of this invention. It is a figure which shows the relationship between the diameter of the refrigerant path in the expansion valve which concerns on embodiment of this invention, and the eigenvalue of a refrigerant path. (A) is a figure which shows the cross section of the refrigerant path in which the shaft is provided, (b) is a figure which shows the relationship between the area reduction ratio of a refrigerant path, and channel | path resistance. (A) is a figure which shows the cross section (permeation | transmission circle diameter) of the refrigerant path in which the shaft is provided, (b) is a figure which shows the relationship between the area reduction ratio of a refrigerant path, and channel | path resistance, (c) FIG. 3 is a diagram showing a cross section (permeation circle diameter) of a refrigerant passage (semicircle). It is a figure which shows the generation | occurrence | production state of a noise when changing a shaft diameter and the diameter of a refrigerant path center part. It is a figure which shows ratio of the projected area of the shaft with respect to the projected area of the refrigerant | coolant channel | path center part when changing a shaft diameter and the diameter of the refrigerant | coolant channel | path center part. It is a figure which shows ratio of the projected area of the shaft with respect to the projected area of the refrigerant | coolant channel | path center part when changing a shaft diameter and the diameter of the refrigerant | coolant channel | path center part. It is a figure which shows the reduction rate of an equivalent circular diameter when changing a shaft diameter and the diameter of a refrigerant path center part. It is a figure which shows the conventional expansion valve.

  The expansion valve 1 which concerns on embodiment of this invention is used for a cooling cycle (for example, the refrigerating cycle of an air conditioner for motor vehicles) similarly to the conventional expansion valve 101 and the expansion valve of patent document 1. FIG.

  Similarly to the conventional expansion valve 101, the expansion valve 1 corresponds to a first refrigerant passage (a refrigerant passage corresponding to the refrigerant passage 104 shown in FIG. 10) and a second refrigerant passage 3 (a refrigerant passage 107 shown in FIG. 10). Refrigerant path).

  The expansion valve 1 is different from the conventional expansion valve 101 in the configuration of the second refrigerant passage (second refrigerant flow path) 3 and the shaft 5, but other portions are the same as those of the conventional expansion valve 101. The configuration is almost the same.

  In FIGS. 1 and 2, the display of the lower portion of the expansion valve 1 (the first passage, the valve portion 109 shown in FIG. 10, etc.) is omitted.

  A shaft 5 is disposed in a second refrigerant passage (hereinafter simply referred to as “refrigerant passage”) 3 of the expansion valve 1. The shaft 5 operates the valve portion in order to adjust the amount of refrigerant flowing through the valve portion (not shown in FIGS. 1 and 2). Note that the refrigerant (for example, R134a) coming out of an evaporator (not shown) flows through the refrigerant passage 3, and the refrigerant flowing through the refrigerant passage 3 reaches the compressor.

  In the expansion valve 1, the eigenvalue F0 of the refrigerant passage 3 in which the shaft 5 is disposed is the frequency of Karman vortex generated by the outer diameter D4 of the shaft 5 (the refrigerant frequency due to Karman vortex in the refrigerant passage) F1. It is set larger than the value. Details of the refrigerant passage central portion 7 will be described later.

  The eigenvalue F0 is the natural frequency of the refrigerant when the refrigerant is flowing through the refrigerant passage 3 including the refrigerant passage central portion 7. As the eigenvalue F0, the value in the refrigerant passage 3 from which the shaft 5 is removed is listed, but the value in the refrigerant path 3 in which the shaft 5 is arranged may be listed.

  The outer shape of the shaft 5 is formed in a columnar shape, and the shaft 5 is disposed in the refrigerant passage 3 in an exposed state.

  More specifically, the expansion valve 1 includes a body (main body block) 9 made of, for example, aluminum or resin. A first refrigerant passage (not shown) through which the refrigerant flows and the refrigerant passage 3 pass through the body 9. As already understood, the refrigerant passage 3 penetrates the body 9 away from the first refrigerant passage.

  One opening of the first refrigerant passage (refrigerant inlet; corresponding to port T1 in FIG. 10) is connected to a receiver / dryer (not shown) via a pipe, and the other of the first refrigerant passage The opening (refrigerant outlet; corresponding to port T2 in FIG. 10) is connected to the evaporator via a pipe.

  One opening of the refrigerant passage 3 (refrigerant inlet; corresponding to the port T3 in FIG. 10) is connected to the evaporator via a pipe, and the other opening (refrigerant outlet; in FIG. 10) of the second refrigerant passage. Port T4 is equivalent) and is connected to the compressor via a pipe.

  A valve portion (not shown) for adjusting the amount of the refrigerant flowing through the first refrigerant passage is provided in the middle of the first refrigerant passage.

  The shaft 5 is supported by the body 9 and extends in the vertical direction in the refrigerant passage 3 (crosses the refrigerant passage 3). The shaft 5 moves in the vertical direction of FIGS. 1 and 2 with respect to the body 9 in accordance with the temperature and pressure (temperature and pressure) of the refrigerant in the refrigerant passage 3. And as above-mentioned, the opening degree of the valve part provided in the 1st refrigerant path is changed, and the quantity of the refrigerant | coolant which flows through a valve part is adjusted.

  In order to prevent the refrigerant in the refrigerant passage 3 from resonating due to Karman vortices generated on the downstream side of the shaft 5 in the refrigerant passage 3 due to the refrigerant flow in the refrigerant passage 3, as described above, the refrigerant passage 3 is set larger than the frequency F1 of Karman vortex generated by the outer diameter of the shaft 5 and the flow of the refrigerant.

  The refrigerant passage 3 is formed in a columnar shape, and the refrigerant flows through the columnar space substantially parallel to the extending direction of the axis of the column (from the right to the left in FIGS. 1 and 2). .

  The outer diameter D4 of the cylindrical shaft 5 is sufficiently smaller than the inner diameter D2 of the cylindrical refrigerant passage 3. The central axis of the shaft 5 (the central axis extending in the vertical direction in FIGS. 1 and 2) and the central axis of the refrigerant passage 3 are orthogonal to each other (intersect at one point). Further, the shaft 5 extends the cylindrical refrigerant passage 3 over the entire length in the radial direction (the vertical direction in FIGS. 1 and 2).

  Further, as shown in FIG. 1, a power element 11 is provided at a location slightly entering upward from the refrigerant passage 3 in the longitudinal direction of the shaft 5 (extending direction of the central axis). One end (upper end) is engaged with the power element 11, and the other end in the longitudinal direction of the shaft 5 (extending direction of the central axis) is engaged with the valve portion.

  And according to the temperature and pressure of the refrigerant detected by the power element 11 (temperature and pressure of the refrigerant coming out of the evaporator), the shaft 5 is appropriately moved in the extending direction of the central axis to adjust the opening of the valve portion. It is supposed to be.

  As in the case of the conventional expansion valve, in the expansion valve 1, the opening degree of the valve portion increases as the shaft 5 moves downward, and the opening degree of the valve portion increases as the shaft 5 moves upward. Becomes smaller.

  Here, the eigenvalue F0 of the refrigerant passage 3 will be described.

  The eigenvalue F0 is expressed by the following approximate expression f1 in a normal use region in consideration of actual operating conditions of the air conditioner. Approximate expression f1; F0 = 135282exp (−0.054 × D2).

  D2 is the inner diameter of the refrigerant passage central portion 7 shown in FIGS. The unit of F0 is Hz, and the unit of D2 is mm.

  In addition, the eigenvalue F0 of the refrigerant passage 3 is not only the inner diameter D2 of the refrigerant passage central portion 7, but also the flow rate (flow velocity) of the refrigerant flowing through the refrigerant passage 3, the inner diameters D1 and D3 of the passages of the insertion joints 13 and 15 (FIG. 2), the distance between the insertion joints 13 and 15 (the length of the refrigerant passage central portion 7) L, and the outer diameter D4 of the shaft 5 also vary.

  However, in practice, the effects of the flow rate of the refrigerant, the inner diameters D1 and D3 of the insertion joints 13 and 15, the length L of the refrigerant passage central portion 7, and the outer diameter D4 of the shaft 5 are small and can be almost ignored. Therefore, in the approximate expression f1, only the inner diameter D2 of the refrigerant passage central portion 7 is adopted as a variable.

  Next, the Karman vortex frequency F1 of the refrigerant by the shaft 5 will be described.

  The Karman vortex frequency F1 is expressed by the following approximate expression f2. Approximate expression f2; F1 = 0.2 × V / D4.

  V is the flow velocity of the refrigerant flowing through the refrigerant passage central portion 7, and the unit is m / sec. The unit of D4 is mm, and the unit of F1 is kHz.

  Next, the characteristic value F0 of the refrigerant passage 3 (refrigerant passage central portion 7) where the shaft 5 is disposed is set to be larger than the Karman vortex frequency F1 generated by the outer diameter D4 of the shaft 5, as shown in FIG. Will be described with reference to FIG.

  The horizontal axis in FIG. 3 indicates the inner diameter D2 of the refrigerant passage central portion 7, and the vertical axis indicates the eigenvalue F0.

  A diagram G1 in FIG. 3 shows the relationship between the inner diameter D2 of the refrigerant passage center 7 and the eigenvalue F0 of the refrigerant passage 3 when the outer diameter D4 of the shaft 5 is 2.4 mm.

  A diagram G2 in FIG. 3 is obtained by moving the diagram G1 downward by a predetermined value (margin value; clearance; for example, 300 Hz). Even if there is an error or the like due to the downward movement of 300 Hz, the eigenvalue F0 of the refrigerant passage 3 can be reliably made larger than the Karman vortex frequency F1.

  Of the diagram G3, the inner diameter D2 is on the left side of the diagram G2.

  A diagram G3 shown in FIG. 3 shows the Karman vortex frequency f1 when the outer diameter D4 of the shaft 5 is 2.4 mm, and shows 5000 Hz. If the inner diameter D2 of the refrigerant passage central portion 7 is set within the range A1 in the diagram G3, the eigenvalue F0> the Karman vortex frequency F1. At the lower limit of the range A1, the inner diameter D2 of the refrigerant passage central portion 7 is preferably about 11 mm, more preferably about 13 mm, and further preferably about 14 mm. At the upper limit of the range A1, the inner diameter D2 of the refrigerant passage central portion 7 traversed by the shaft 5 is about 17 mm.

  A diagram G4 shown in FIG. 3 shows the Karman vortex frequency when the outer diameter D4 of the shaft 5 is 2.2 mm, and shows 5500 Hz. If the inner diameter D2 of the refrigerant passage central portion 7 is set within the range A2 in the diagram G4, the eigenvalue F0> the Karman vortex frequency F1. At the lower limit of the range A2, the inner diameter D2 of the refrigerant passage central portion 7 is preferably about 10 mm, more preferably about 12 mm, and further preferably about 13 mm. At the upper limit of the range A2, the inner diameter D2 of the refrigerant passage central portion 7 traversed by the shaft 5 is about 16 mm.

  A diagram G5 shown in FIG. 3 shows the Karman vortex frequency when the outer diameter D4 of the shaft 5 is 2.9 mm, and shows 4800 Hz. If the inner diameter D2 of the refrigerant passage central portion 7 is set within the range A3 in the diagram G5, the eigenvalue F0> the Karman vortex frequency F1. At the lower limit of the range A3, the inner diameter D2 of the refrigerant passage central portion 7 is preferably about 13 mm, more preferably about 16 mm, and further preferably about 17 mm. At the upper limit of the range A3, the inner diameter D2 of the refrigerant passage central portion 7 traversed by the shaft 5 is about 18 mm.

  The expansion valve 1 will be further described.

  In the expansion valve 1, the projected area S1 of the shaft 5 is 25% or less (or less) of the projected area S2 of the refrigerant passage 3 (refrigerant passage central portion 7).

  The projected area S1 of the shaft 5 is the area of the shaft 5 (the area of the portion indicated by the oblique lines in FIG. 4A) when the cylindrical refrigerant passage central portion 7 is viewed from the extending direction of the central axis. .

The projected area S2 of the refrigerant passage central portion 7 is an area of the refrigerant passage central portion 7 when the cylindrical refrigerant passage central portion 7 is viewed from the extending direction of the central axis. That is, the area of the cross section of the refrigerant passage central portion 7 (the cross section taken along a plane orthogonal to the extending direction of the central axis of the refrigerant passage 3), and when the inner diameter of the refrigerant passage central portion 7 is D2, the refrigerant passage central portion the projected area S2 of 7, wherein f3; represented by ^{S2 = π × D2 2/4} .

  In the expansion valve 1, S1 / S2 ≦ 0.25. That is, the projection area S1 / projection area S2 is within the range A4 shown in FIG. It is desirable that S1 / S2 be within the range of 0.10 to 0.25 (more preferably within the range of 0.12 to 0.25). Note that S1 / S2 ≦ 0.30 may be satisfied.

  In the expansion valve 1, the outer diameter D4 of the shaft 5 is, for example, 2.0 mm or more and 3 mm or less (preferably 2.2 mm or more and 3 mm or less).

  Furthermore, it is desirable that the outer diameter D4 of the shaft 5 is 2.9 mm or less. At this time, the inner diameter D2 of the refrigerant passage central portion 7 refrigerant is preferably 14 mm or more and 19 mm or less.

  However, the outer diameter D4 of the shaft 5 is desirably 2.0 mm or more (more preferably 2.2 mm or more) so that the Karman vortex frequency F1 is not too high. If the generation of noise can be suppressed by other conditions, the above value of 25% may be exceeded. In this case, for example, 30% or less is desirable.

  Further, in the expansion valve 1, the refrigerant passage 3 in which the shaft 5 is not present in the “D” -shaped refrigerant passage section 17 (see FIG. 5A) in the portion of the refrigerant passage 3 where the shaft 5 is provided. Compared with the semicircle 19 (see FIG. 5C) of the part 7 in FIG. 5, the reduction rate of the equivalent circular diameter is 16% or less.

  More specifically, the “D” -shaped refrigerant passage section 17 is a portion of one refrigerant passage of the two refrigerant passages divided into two equal parts by the shaft 5. FIG. 5A is a view of the portion 7 of the refrigerant passage 3 in which the shaft 5 is provided as viewed from the flow direction of the refrigerant.

  Further, the semicircle 19 in the portion 7 of the refrigerant passage 3 where the shaft 5 is not present is the two refrigerant passages formed by dividing the circular refrigerant passage central portion 7 into two equal parts with a predetermined diameter. It is a part of one of the refrigerant passages. FIG. 5C is a view of the refrigerant passage when the shaft 5 is removed as seen from the refrigerant flow direction.

  The equivalent circular diameter De1 of the “D” -shaped refrigerant passage section 17 in the portion 7 of the refrigerant passage 3 where the shaft 5 is provided is expressed by the equation f4; De1 = 4 × Af1 / Wp1. Af1 is the area of the “D” -shaped portion 17, and Wp1 is the wet length (the entire circumference of the outer periphery of the “D” -shaped portion 17; the length of the wall surface of the “D” -shaped portion 17 ). In the calculation using the equation f4, the recessed portion 2 (see FIGS. 1 and 2) around the shaft 5 that is countersunk may be ignored.

  The equivalent circular diameter De2 of the semicircle 19 in the portion 7 of the refrigerant passage 3 where the shaft 5 is not present is expressed by the equation f7; De2 = 4 × Af2 / Wp2. Af2 is the area of the semicircular part, and Wp2 is the wetting length (the length of the wall surface of the semicircular part). De1 and De2 are dimensionless numbers.

  In the expansion valve 1, (De2-De1) /De2≦0.16. That is, the reduction rate (De2-De1) / De2 of the equivalent circular diameter is within the range A5 shown in FIG. Note that (De2-De1) / De2 may fall within the range of 0.13 (or 0.125) to 0.16.

  Further, as shown in FIG. 1, insertion joints 13 and 15 are inserted into the refrigerant passage 3 of the expansion valve 1, and the value of the inner diameter D <b> 2 of the refrigerant passage 3 (refrigerant passage central portion 7) is the insertion joint 13. , 15 is larger than the values of the inner diameters D1, D3.

  The joints (insertion joints) 13 and 15 are provided by being inserted into both ends of one end of the refrigerant passage 3 and the other end of the refrigerant passage 3, respectively.

  That is, an inlet side joint (upstream side joint) 13 that is inserted into the refrigerant path 3 from the refrigerant passage inlet and provided at the refrigerant inlet as a joint and the inlet flow side joint 13 are separate from each other, and the refrigerant path An outlet side joint 15 that is inserted into the refrigerant passage 3 from the outlet and provided at the refrigerant outlet is provided.

  Then, the value of the length L in the axial direction of the central portion 7 of the refrigerant passage 3 is divided by the value of the depth D in the radial direction of the central portion 7 of the refrigerant passage 3. In the expansion valve 1, the value of the parameter a obtained by multiplying the value of the inner diameter dimension (D1 or D3) is less than 40.

  More specifically, a cylindrical portion 21 (a portion having an outer diameter equal to the inner diameter D2 of the refrigerant passage 3 and an inner diameter D1) 21 of the upstream joint 13 enters the refrigerant passage 3. A cylindrical portion (a portion having an outer diameter equal to the inner diameter D <b> 2 of the refrigerant passage 3 and an inner diameter D <b> 3) 23 of the downstream side joint 15 enters the refrigerant passage 3.

  The tip of the cylindrical portion 21 of the upstream joint 13 inserted in the refrigerant passage 3 (the right end in FIG. 1) and the tip of the cylindrical portion 23 of the downstream joint 15 inserted in the refrigerant passage 3 (The left end in FIG. 1) are separated from each other by a distance L. A central portion (refrigerant passage central portion) 7 where the joints 13 and 15 are not present is formed at the central portion of the refrigerant passage 3.

  The shaft 5 is provided at the center of the refrigerant passage central portion 7 and is separated from the upstream side joint 13 and the downstream side joint 15.

  The dimension L of the axial length of the refrigerant passage central portion 7 is the dimension of the refrigerant passage central portion 7 in the extending direction of the central axis of the central portion 7 of the refrigerant passage, as already understood. That is, it is a dimension between the upstream joint 13 and the downstream joint 15.

  The depth D in the radial direction of the refrigerant passage central portion 7 is the inner diameter D3 (inner diameter) of the cylindrical portion of the downstream joint 15 (or the upstream joint 13) from the value of the diameter D2 of the refrigerant passage central portion 7. The value obtained by subtracting the value of D1 may be divided by “2”.

  The parameter is “a”, the dimension of the axial length of the refrigerant passage central portion 7 is “L”, the depth of the refrigerant passage central portion 7 in the radial direction is “D”, and the cylinder of the downstream joint 15 When the inner diameter dimension of the portion 23 is “D3”, the parameter a is expressed by the equation f8; a = L / D × D3. Further, the depth dimension D in the radial direction of the refrigerant passage central portion 7 is represented by the formula f9; D = (D2−D3) / 2. “A” is a dimensionless number.

  In the expansion valve 1, since the eigen value F0 varies depending on the inner diameter D2 of the refrigerant passage central portion 7, the inner diameter D2 of the refrigerant passage central portion 7 is made smaller than before in order to increase the eigenvalue F0 (for example, 18 mm is reduced to 15 mm did).

  In the expansion valve 1, for example, D1 is 12 mm, D2 is 15 mm, D3 is 13, 7 mm, D4 is 2, 4 mm, and L is 12 mm.

  The expansion valve 1 operates in the same manner as the conventional expansion valve 101 and the like. That is, the flow rate of the refrigerant flowing through the evaporator is appropriately adjusted according to the temperature and pressure of the refrigerant flowing through the refrigerant passage 3.

  In the test result shown in FIG. 6, the dimension L of the axial length of the refrigerant passage central portion 7 is fixed to 18 mm, and the inner diameter D2 of the refrigerant passage central portion 7 and the outer diameter D4 of the shaft 5 are changed. . In the case shown in FIG. 6, the noise is within the allowable range at the circle mark.

  That is, when the inner diameter D2 is in the range of 10 mm to 19 mm and the outer diameter D4 of the shaft 5 is in the range of 2.8 mm to 5.0 mm, or the inner diameter D2 is in the range of 10 mm to 18 mm. When the outer diameter D4 of the shaft 5 is in the range of 2.6 mm to 2.8 mm, or the inner diameter D2 is in the range of 10 mm to 17 mm, and the outer diameter D4 of the shaft 5 is 2.4 mm. When the inner diameter D2 is within the range of 10 mm to 15 mm and the outer diameter D4 of the shaft 5 is within the range of 2.2 mm to 2.4 mm, or When the inner diameter D2 is in the range of 10 mm to 14 mm and the outer diameter D4 of the shaft 5 is in the range of 2.0 mm to 2.2 mm, the noise is within the allowable range.

  More specifically, the inner diameter D2 of the refrigerant passage center 7 and the shaft 5 such that the range shown by the thick frame shown in FIG. 7 (the range in which the number in the frame is 0.18 to 0.30) are set. If the outer diameter D4 is adopted, generation of noise can be suppressed.

  In addition, instead of FIG. 7, the inner diameter D <b> 2 of the refrigerant passage central portion 7 that can suppress noise by using FIG. 8 (range indicated by a thick frame; the range in which the number in the frame is 0.18 to 0.25). And the outer diameter D4 of the shaft 5 may be employed.

  In the test results shown in FIG. 9, the dimension L of the axial length of the refrigerant passage central portion 7 is fixed to 18 mm, and the inner diameter D2 of the refrigerant passage central portion 7 and the outer diameter D4 of the shaft 5 are changed. . In the case shown in FIG. 9, noise can be suppressed within a range indicated by a thick frame.

  The numbers such as “0.847” shown in FIG. 9 assume that the outer diameter of the shaft 5 is “0” and the fluid diameter ratio when the fluid diameter obtained by equally dividing the refrigerant passage central portion 7 is “1”. Is shown. A value obtained by subtracting “0.847” from “1” (for example, 1−0.847 = 0.153) is a reduction rate of the equivalent circular diameter. If the rate of reduction of the equivalent circular diameter is 0.13 (13%) to 0.16 (16%), noise can be suppressed.

  According to the expansion valve 1, since the outer shape of the shaft 5 is formed in a cylindrical shape and the shaft 5 is exposed in the refrigerant passage 3 (refrigerant passage central portion 7), a cover surrounding the shaft 5 is provided. In addition, the configuration is simplified by eliminating the need to form dimples or the like on the outer surface of the shaft 5 by applying dimple processing or the like to the outer surface of the shaft 5. Further, the outer surface of the shaft 5 has a smooth shape with no irregularities. Therefore, the flow path resistance of the refrigerant passage 3 can be reduced.

  Further, according to the expansion valve 1, the eigenvalue F0 of the refrigerant passage central portion 7 in which the shaft 5 is arranged is set to be larger than the Karman vortex frequency F1 generated by the shaft 5, so that the shaft 5 is arranged. When the refrigerant flows through the refrigerant passage 3, resonance between the Karman vortex generated by the shaft 5 and the refrigerant in the refrigerant passage 3 can be avoided, and generation of noise can be prevented.

  Further, in order to lower the Karman vortex frequency F1 in the expansion valve 1, the diameter of the shaft 5 may be increased. However, by increasing the diameter of the shaft 5, the projected area S1 in the refrigerant passage 3 is increased and the passage resistance of the refrigerant flow is increased. Will go up. However, in the expansion valve 1, the projected area S 1 of the shaft 5 is 25% or less of the projected area S 2 of the refrigerant passage central portion 7, so that the refrigerant due to an increase in the projected area S 1 of the shaft 5 in the refrigerant passage 3. An increase in the flow path resistance can be suppressed, and the Karman vortex frequency F1 can be lowered appropriately.

  Further, according to the expansion valve 1, since the cover is not provided as in the prior art, even if the substantial outer diameter of the shaft 5 in the refrigerant passage 2 is reduced and the Karman vortex frequency F1 is increased, the refrigerant is reduced. Generation | occurrence | production of a noise can be prevented because the internal diameter D2 of the channel | path center part 7 is small compared with the conventional one.

  Further, according to the expansion valve 1, the reduction rate of the equivalent circular diameter is 16% or less in the “D” -shaped refrigerant passage section 17 in the portion 7 of the refrigerant passage 3 where the shaft 5 is provided. The friction loss on the wall surface (the refrigerant passage and the shaft wall surface) through which the refrigerant flows can be reduced, and the passage resistance of the refrigerant flow in the portion 7 of the refrigerant passage 3 provided with the shaft 5 can be suppressed. .

  Further, according to the expansion valve 1, the value of the inner diameter D2 of the refrigerant passage central portion 7 is larger than the values of the inner diameters D1 and D3 of the joints 13 and 15, so that the passage resistance in the refrigerant passage 2 increases. Is suppressed.

  Further, according to the expansion valve 1, even if the value of the parameter a is set to less than 40, the eigenvalue F0 of the refrigerant passage 3 in which the shaft 5 is disposed is the Karman vortex generated by the outer diameter D4 of the shaft 5. Since it is set to be larger than the frequency F1, it is possible to prevent the generation of noise due to the flow of the refrigerant.

1 Expansion Valve 3 Refrigerant Passage 5 Shaft 7 Refrigerant Passage Part 13 Joint (Inlet Side Insertion Joint)
15 Fitting (Outlet side insertion fitting)
17 “D” -shaped refrigerant passage cross-section a Parameter D Radial depth of the central portion of the refrigerant passage D1 Inner diameter dimension of the inlet side insertion joint D3 Inner diameter dimension of the outlet side insertion joint F0 Eigenvalue of the refrigerant path F1 Karman vortex frequency L Length in the axial direction of the central part of the refrigerant passage S1 Projected area of the shaft S2 Projected area of the refrigerant passage

Next, the eigenvalues F0 of the refrigerant passage 3 in which the shaft 5 is positioned (the coolant passage middle portion 7) is, Ru is set larger than the frequency F1 of the Karman vortex generated by the outside diameter D4 of the shaft 5, FIG. 3 Will be described with reference to FIG.

Claims (6)

A shaft that operates the valve portion to adjust the amount of refrigerant flowing through the valve portion is an expansion valve disposed in a refrigerant passage through which the refrigerant flows,
The eigenvalue of the refrigerant passage in which the shaft is arranged is set to be larger than the frequency of Karman vortex generated by the outer diameter of the shaft,
An expansion valve characterized in that an outer shape of the shaft is formed in a cylindrical shape, and the shaft is disposed in the refrigerant passage in an exposed state. The expansion valve according to claim 1,
An expansion valve, wherein a projected area of the shaft is 30% or less of a projected area of the refrigerant passage. The expansion valve according to claim 1 or 2,
The shaft has a diameter of 3 mm or less. The expansion valve according to any one of claims 1 to 3,
An expansion valve characterized in that a reduction rate of an equivalent circular diameter is 16% or less in a "D" -shaped refrigerant passage section in a portion of the refrigerant passage where the shaft is provided. The expansion valve according to any one of claims 1 to 4,
A joint is inserted in the refrigerant passage,
The expansion valve according to claim 1, wherein an inner diameter value of the refrigerant passage is larger than an inner diameter value of the joint. The expansion valve according to claim 5,
The joint is inserted into one end of the refrigerant passage and the other end of the refrigerant passage,
Obtained by multiplying the value of the axial length of the central portion of the refrigerant passage by the value of the radial depth of the central portion of the refrigerant passage and the value of the inner diameter of the joint. An expansion valve having a parameter value set to less than 40.

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