JP2007032980A - Expansion valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an expansion valve suitable for refrigerant flow control, reducing refrigerant flow sound and having proof stress to plugging of foreign matter in a refrigerating cycle. <P>SOLUTION: A valve chamber 5 provided with a fluid inflow port 32 formed in a side face, and a valve seat 6 formed at a bottom face is formed inside an expansion valve body part 3 of the expansion valve 1, and a needle 2 that can advance to and retreat from the valve seat 6 is installed penetrating the top face of the valve chamber 5. A needle tip part 4 gradually reduced in diameter in a flow-out direction is formed at the tip of the needle 2. The valve seat 6 is formed with an orifice inlet part 7 gradually reduced in diameter in the flow-out direction, an orifice center part 8 of approximately cylindrical shape, and an orifice outlet part 9 gradually enlarged in diameter in the flow-out direction. A clearance passage 47 gradually narrowed in the flow-out direction is thereby formed by the needle tip part 4 and the orifice inlet part 7, and the separation of refrigerant flow is reduced in the start position of the orifice center part 8. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an expansion valve for fluid, and more particularly to an expansion valve suitable for reducing refrigerant flow noise.

  In a conventional refrigeration cycle apparatus for an air conditioner, a variable capacity compressor such as an inverter is used in order to cope with a change in air conditioning load. The rotational frequency of the compressor is controlled according to the size of the air conditioning load, and the throttle amount of the expansion valve is adjusted in order to effectively use the evaporator and the condenser in accordance with the rotational speed of the compressor. At this time, the refrigerant flowing into the expansion valve may be a vapor single phase, a liquid single phase, or a gas-liquid two phase. In each case, there is a problem that noise occurs in the expansion valve. In particular, when passing in a gas-liquid two-phase, the noise frequency fluctuates, which is annoying.

  In order to prevent such noise, for example, an invention is disclosed in which a porous body is installed at each of an inlet (a terminal portion of an inflow pipe) and an outlet (a start end of an outflow pipe) of a valve chamber of an expansion valve. That is, since the flow state of the refrigerant flowing into the expansion valve is a flow accompanied by a bubble soul, when the refrigerant passes through the porous body, it is shifted to a flow state in which the gas phase and the liquid phase are mixed, Since the refrigerant pressure pulsation in the part becomes continuous, the refrigerant noise and the pipe vibration are reduced (see, for example, Patent Document 1).

  Furthermore, for example, an invention is disclosed in which a honeycomb pipe and a cylindrical pipe in which a plurality of small diameter tubes are bundled are alternately arranged in a predetermined range close to the expansion valve of the inflow pipe and a predetermined range close to the expansion valve of the outflow pipe. Yes. That is, a silencer is formed by the honeycomb pipe and the cylindrical pipe, and the refrigerant repeats homogenization and expansion in the process of passing through the silencer, and transmission of generated noise and pressure pulsation during decompression is suppressed (for example, , See Patent Document 2).

JP-A-7-146032 (page 3-4, FIG. 1) JP-A-11-325655 (page 4-6, FIG. 2)

  However, in the invention disclosed in Patent Document 1 or 2, foreign matter in the refrigeration cycle is captured by the porous body or the honeycomb pipe, which may cause clogging of the foreign matter. There was a problem that heating performance could not be realized.

  The present invention has been made to solve the above-described problems, and is intended to obtain an expansion valve that is suitable for refrigerant flow control, reduces refrigerant flow noise, and is resistant to clogging of foreign matters in the refrigeration cycle. And

An expansion valve according to the present invention includes a valve chamber having a fluid inlet formed on a side surface and a fluid outlet formed on a bottom surface, and penetrating the top surface of the valve chamber toward the outlet. Having a needle that can be advanced and retracted,
An orifice inlet portion that gradually decreases in diameter toward the outflow direction at the outflow port, and a substantially cylindrical orifice central portion is formed on the outflow side of the orifice inlet portion,
A needle tip portion that gradually becomes smaller in diameter toward the outflow direction is formed at the tip of the needle,
A gap channel that gradually narrows in the outflow direction is formed by the orifice inlet and the needle tip.

  As described above, according to the present invention, a “tapered gap channel” that gradually narrows in the outflow direction is formed by the needle tip and the orifice inlet, thereby preventing the generation of refrigerant flow noise. As a result, noise can be reduced, and even if there is a foreign substance in the refrigeration cycle in which such a pressure reducing valve is installed, there is no risk of foreign matter clogging, and the original cooling performance and heating performance can be realized. Is obtained. Moreover, since it is not necessary to provide a porous body such as a honeycomb pipe in the flow path, the manufacturing cost and the maintenance cost are reduced.

[Embodiment 1]
(Electric expansion valve)
1 and 2 are a configuration diagram and a sectional configuration diagram showing an example of an expansion valve according to Embodiment 1 of the present invention. 1 and 2, an electric expansion valve 1 (hereinafter referred to as “expansion valve 1”) includes a needle 2 and an expansion valve body 3, and a valve chamber 5 is formed inside the expansion valve body 3. .

(needle)
A needle through hole 31 is formed in the top surface of the expansion valve body 3 (same as the top surface of the valve chamber 5), and the needle 2 is inserted into the needle through hole 31 in a fluid-tight manner so as to be slidable. Further, a stepping motor 10 is installed on the upper portion of the expansion valve main body 3, and the rotation angle of the stepping motor 10 is converted into a translation distance by a rotation / translation conversion mechanism (not shown) and used for the raising / lowering operation of the needle 2. Note that the tip of the needle 2 is reduced in diameter to form a needle tip 4 (the same as the range ABC in the figure). The shape of the needle tip 4 is not limited, and may be configured with, for example, a one-step taper that is a linear taper or a multi-step taper whose angle changes in multiple steps.

(valve seat)
A valve seat 6 constituting an outlet is formed on the bottom surface of the valve chamber 5. The valve seat 6 has an orifice inlet portion 7 (same as the range DE in the drawing) that gradually decreases in diameter in the outflow direction (downward in the figure), and substantially on the outflow side of the orifice inlet portion 7. A cylindrical orifice central portion 8 (same as the range EF in the figure) and an orifice outlet portion 9 (F- in the figure) that gradually increases in diameter toward the outflow direction toward the outflow side of the orifice central portion 8. The same as the range of G).
At this time, the length of the orifice inlet portion 7 (same as the vertical distance between the start position D and the end position E) and the length of the orifice outlet portion 9 (same as the vertical distance between the start position F and the end position G) Are 5 times the diameter of the orifice inlet 7. The shapes of the orifice inlet portion 7 and the orifice outlet portion 9 are not limited. For example, the orifice inlet portion 7 and the orifice outlet portion 9 may be configured with a single-stage taper that is a linear taper or a multi-stage taper whose angle changes in multiple stages.

(Gap channel)
The needle tip 4 of the needle 2 enters the orifice inlet 7 to form a gap channel 47. At this time, the angle α formed between the needle tip 4 and the orifice inlet 7 is 60 °. That is, a line connecting the final end position A forming the needle 2 (corresponding to the intersection with the needle tip 4 at the end of the parallel part of the needle 2) and the tip position C of the needle tip 4; The angle formed by the line connecting the start position D of the orifice inlet portion 7 and the end position E of the orifice inlet portion 7 (same as the start position of the orifice central portion 8) is 60 °.
The orifice outlet portion 9 is tapered, and the taper angle β is 60 °. That is, the angle formed by the line connecting the start position F and the end position G of the orifice outlet 9 and the line connecting the start position F and the end position G at the diagonal positions is 60 °.

(Inflow pipe, outflow pipe)
A refrigerant inlet 32 is formed on the side surface of the expansion valve main body 3 (same as the side surface of the valve chamber 5), and a connecting pipe 20 (hereinafter referred to as “inflow pipe 20”) is horizontally installed in the inlet 32. Yes.
An outflow pipe installation groove 33 is formed on the bottom surface of the expansion valve body 3 (same as the bottom surface of the valve chamber 5) so as to surround the orifice outlet portion 9, and the connection pipe 30 (hereinafter “ An outflow pipe 30 ").
The inflow pipe 20 and the outflow pipe 30 are copper pipes and are welded to the expansion valve main body 3 made of brass, but the material forming the members is not limited.
Therefore, the refrigerant (not shown) flows into the valve chamber 5 via the inflow pipe 20, and the gap flow path 47 formed by the needle tip portion 4 and the orifice inlet portion 7 and the cylindrical orifice central portion 8. And then flows out into the outflow pipe 30 through the tapered orifice outlet 9.

(Refrigeration cycle)
FIG. 3 is a refrigerant circuit diagram illustrating an example of a refrigeration cycle in which the expansion valve according to Embodiment 1 of the present invention is installed. In FIG. 3, the refrigeration cycle 100 includes a compressor 21, a condenser 22, an expansion valve 1 that is a throttle mechanism, an evaporator 23, a pipe 24 that is sequentially connected, and a pipe 25 (corresponding to the inflow pipe 20). ), A pipe 26 (corresponding to the outflow pipe 30), and a pipe 27. The mass flow rate of the refrigerant is about 20 kg / h to 200 kg / h.

4 is a conceptual diagram of a Ph diagram of the refrigeration cycle shown in FIG. The positions “I, B, C, and D” in FIG. 4 correspond to the positions “I, B, C, and D” of the refrigeration cycle shown in FIG.
That is, in the expansion valve 1, the refrigerant is decompressed in an isenthalpy (isoentropic) manner.

(Refrigerant flow)
FIGS. 5A and 5B are partial schematic diagrams for explaining the state of the refrigerant flowing into the expansion valve according to Embodiment 1 of the present invention, where FIG. 5A is the present invention, and FIG. 5B is a conventional expansion valve for comparison. is there.
In FIG. 5A, in the normal cooling operation, by driving the stepping motor 10 of the expansion valve 1 that is a throttle device, the needle tip 4 of the needle 2 is inserted into the orifice inlet 7 and the gap channel 47 is formed. It is formed. That is, by controlling the stepping motor 10, the gap area is adjusted and the flow rate of the refrigerant is adjusted.
For example, in the configuration of the needle tip portion 4 and the orifice inlet portion 7 having a predetermined shape, the clearance area is adjusted so that the mass velocity of the refrigerant passing through the needle tip portion 4 and the orifice inlet portion 7 is 400 kg / m ² s to 10,000 kg / m ³ s.

  At this time, the compressor 21 is operated at the number of rotations corresponding to the air conditioning load, and the refrigerant that has become high-temperature and high-pressure vapor refrigerant in the compressor 21 (same as in state b) is the condenser 22 (same as in the outdoor heat exchanger). Is condensed and liquefied (same as in state c), and further decompressed at expansion valve 1 to become a low-pressure two-phase refrigerant (same as in state d). The low-pressure two-phase refrigerant flows into the evaporator 23 and evaporates (same as in the state A), returns to the compressor 21 and becomes vapor refrigerant again.

In FIG. 5A, the gas-liquid two-phase refrigerant flows into the valve chamber 5 from the inflow pipe 20 installed horizontally. Then, it flows into the gap flow path 47 constituted by the needle tip portion 4 and the orifice inlet portion 7, and subdivides the vapor slag while reducing the pressure, and the liquid refrigerant and the vapor refrigerant are mixed. Then, the refrigerant in the mixed state flows more smoothly than before, and flows into the main throttle portion composed of the orifice central portion 8 (the same as the smallest gap portion), so that the separation flow at the orifice central portion 8 is suppressed. There is an effect to. Therefore, discontinuous pressure fluctuations do not occur and noise is reduced.
That is, the flow separation at the start position E of the orifice central portion 8 is less likely to occur. Since noise is considered to be caused by fluctuations in the development and disappearance of this separation flow and the separation flow itself, it is preferable to suppress separation as much as possible as a noise reduction measure, and the present invention suppresses this separation. ing.
Further, the orifice outlet 9 rectifies the gas-liquid two-phase jet flowing out from the constricted portion formed by the orifice central portion 8 with a taper enlarged to the outflow side, thereby reducing pressure fluctuation due to the jet and reducing noise. It can be reduced.

In FIG. 5B, conventionally, the refrigerant condensed in the condenser flows into the expansion valve. However, the state of the refrigerant fluctuates depending on the use environment condition or at the time of start-up, and is in a gas-liquid two-phase state or liquid single-phase state. It has been known that noise occurs in the expansion valve due to the flow. In particular, when flowing in a gas-liquid two-phase refrigerant in a fluid state in which the gas-liquid two phases are intermittent, such as a slag flow or a plug flow, discontinuous noise is generated in the expansion valve.
That is, in the conventional orifice, since the bottom surface of the valve chamber 50 forms the valve seat 60, the clearance channel 460 is formed by the inner peripheral edge J (same as the start position) of the valve seat 60 and the needle 40. Therefore, flow separation occurs at the start position J at the orifice inlet, and the fluctuation between the development and disappearance of the separation flow, and the separation flow itself is considered to cause noise. At this time, the portion (foaming point) where the liquid refrigerant starts to foam fluctuates in the valve seat 60 (the same as the throttle portion and J-K) where the separation flow has occurred. Inside the separation flow, a vortex is generated at the orifice inlet portion (near start position J), and this vortex develops with time. The developed vortex can no longer stop at the entrance, and is flowed downstream to release energy. Due to the behavior of a series of vortices, the foaming point varies, so the flow rate of the refrigerant also varies. As a result, pressure fluctuation occurs and noise is generated.

(Orifice shape)
6 and 7 are measurement results showing the relationship between the shape of the expansion valve and the noise level according to Embodiment 1 of the present invention.
In FIG. 6, the angle α formed between the needle tip 4 and the orifice inlet 7 is referred to as a “taper angle” for convenience, and the relationship between the taper angle and the noise level difference is normalized with the noise level at a taper angle of 30 ° being zero. It shows. This noise level is a result of measuring noise by providing a taper at the orifice inlet 7 of the expansion valve 1 and flowing a gas-liquid two-phase fluid. It can be seen that the noise level is reduced when the taper angle is 60 ° or less.

  In FIG. 7, the relationship between the length of the orifice inlet portion 7 normalized by the inner diameter d of the orifice central portion 8 and the noise level difference of the expansion valve 1 is shown. The length of the orifice inlet portion 7 is defined by the distance between the start position D and the end position E of the orifice inlet portion 7 in the vertical direction (same in the vertical direction in the figure). The noise level difference represents the noise level with respect to each length, with the noise level of the length 5d of the orifice inlet 7 being 0. The noise level is the lowest at the length 5d of the orifice inlet 7.

(Other embodiments)
As described above, the refrigerant flows into the valve chamber 5 through the inflow pipe 20, and the gap channel 47 formed by the needle tip portion 4 and the orifice inlet portion 7, the orifice central portion 8, and the tapered orifice. Although what passes through the exit part 9 and flows out into the outflow pipe 30 is shown, the present invention is not limited to this, and the refrigerant may flow in the opposite direction.
That is, when refrigerant flows into the valve chamber 5 from the bottom surface of the expansion valve 1 and flows out from the side surface, or in a refrigeration cycle in which cooling operation and heating operation are switched by a four-way valve, intermittent air such as slag flow or plug flow is used. Similarly, when the liquid two-phase refrigerant flows into the orifice outlet portion 9, the vapor refrigerant is subdivided and mixed with the liquid refrigerant and simultaneously rectified by the outlet side taper of the orifice outlet portion 9. And since it flows into the clearance channel (throttle part) comprised by the orifice inlet part 7 and the needle front-end | tip part 4 via the orifice center part 8, it is effective in a pressure fluctuation being suppressed and noise being reduced.

The block diagram which shows an example of the expansion valve which concerns on Embodiment 1 of this invention. The cross-sectional block diagram which shows an example of the expansion valve which concerns on Embodiment 1 of this invention. The refrigerant circuit figure which shows an example of the refrigerating cycle in which the expansion valve shown in FIG. 2 was installed. The conceptual diagram of the Ph diagram of the refrigerating cycle shown in FIG. The partial schematic diagram explaining the state of the refrigerant | coolant which flows in into the expansion valve shown in FIG. The measurement result which shows the relationship between the shape of the expansion valve shown in FIG. 2, and a noise level. The measurement result which shows the relationship between the shape of the expansion valve shown in FIG. 2, and a noise level.

Explanation of symbols

1: electric expansion valve, 2: needle, 3: expansion valve body, 4: needle tip, 5: valve chamber, 6: valve seat, 7: orifice inlet, 8: orifice central, 9: orifice outlet 10: stepping motor, 20: inflow pipe, 21: compressor, 22: condenser (outdoor heat exchanger), 23: evaporator, 24: pipe, 25: pipe, 26: pipe, 27: pipe, 30: Outflow pipe, 31: Needle through hole, 32: Inlet, 33: Outlet pipe installation groove, 47: Clearance channel, α: Angle formed by needle tip and orifice inlet angle, β: Taper angle of orifice outlet A: final end position (needle), C: tip position (needle), D: start position (orifice inlet section), E: end position (orifice inlet section), F: start position (orifice outlet section), G : End position (orifice outlet), d: Inner diameter (orifice center).

Claims (6)

A valve chamber having a fluid inlet formed on a side surface and a fluid outlet formed on a bottom surface;
An expansion valve having a needle that penetrates the top surface of the valve chamber and is movable forward and backward toward the outlet,
An orifice inlet portion that gradually decreases in diameter toward the outflow direction at the outflow port, and a substantially cylindrical orifice central portion is formed on the outflow side of the orifice inlet portion,
A needle tip portion that gradually becomes smaller in diameter toward the outflow direction is formed at the tip of the needle,
An expansion valve characterized in that a gap channel that gradually narrows toward the outflow direction is formed by the orifice inlet and the needle tip. A valve chamber having a fluid inlet formed on a side surface and a fluid outlet formed on a bottom surface;
An expansion valve having a needle that penetrates the top surface of the valve chamber and is movable forward and backward toward the outlet,
An orifice inlet portion that gradually decreases in diameter toward the outflow direction, an approximately cylindrical orifice central portion on the outflow side of the orifice inlet portion, and an outflow side of the orifice central portion in the outflow direction. And an orifice outlet that gradually increases in diameter,
A needle tip portion that gradually becomes smaller in diameter toward the outflow direction is formed at the tip of the needle,
An expansion valve characterized in that a gap channel that gradually narrows toward the outflow direction is formed by the orifice inlet and the needle tip.   The expansion valve according to claim 1 or 2, wherein an angle formed by an inner surface of the orifice inlet portion and an outer surface of the needle tip portion is 60 ° or less.   The expansion valve according to claim 2 or 3, wherein the orifice outlet has a taper angle of 60 ° or less.   The expansion valve according to any one of claims 1 to 4, wherein a length of the orifice inlet portion is not less than five times a diameter of the orifice central portion. The expansion valve according to any one of claims 2 to 5, wherein a length of the orifice outlet portion is not less than five times a diameter of the orifice central portion.

Images