JP2000230665A - Cooling cycle-service pressure reducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling cycle-service pressure reducing device which is capable of preventing dust from being deposited on a sliding surface of a piston and of stabilizing a difference pressure control irrespective of fluctuation of a dynamic pressure acting on the piston. SOLUTION: A pressure reducing device 3 has housings 311, 312, 313, a piston 323 disposed in a cylinder chamber 322, and a valve body 317 connected to the piston 323 for opening and closing a pressure reducing hole 316. The housings 311, 312, 313 have the pressure reducing hole 316 formed in refrigerant channels 319, 320 between a refrigerant inlet 314 and a refrigerant outlet 315, the cylinder chamber 322 communicating with the refrigerant channels 319, 320, and a controlling fluid inlet 326 communicated with the cylinder chamber 322. A difference pressure between a fluid pressure exerted on at least a portion ranging from the controlling fluid inlet 326 to one end surface of the piston 323 controls an opening of the pressure reducing hole 316 depending on the valve body 317. On this occasion, a shielding wall 36 is disposed between the refrigerant channels 319, 320 and the other end surface of the piston 323 in the housings 311, 312, 313.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure reducing device which is preferably used for a cooling cycle of an air conditioner for a vehicle, and more particularly to a pilot pressure reducing device having a piston.

[0002]

2. Description of the Related Art In a cooling cycle of an air conditioner for vehicles, R is used.
Fluorocarbon refrigerants such as -12 and R134a are used, but if these are released into the atmosphere, there is a concern about environmental problems such as global warming due to destruction of the ozone layer. For this reason, a cooling cycle using carbon dioxide, ethylene, ethane, nitric oxide or the like has been proposed as one of the measures against defluorocarbons (for example, see Japanese Patent Publication No. Hei 7-18602).

The cooling cycle using carbon dioxide or the like as a refrigerant is in principle the same as the conventional cooling cycle using chlorofluorocarbon. For example, the critical temperature of carbon dioxide is about 31 ° C., which is the critical temperature of chlorofluorocarbon. (For example, R-12
Is 112 ° C), so in summer when the outside air temperature rises, the temperature of carbon dioxide on the radiator (gas cooler) side becomes higher than the critical temperature of carbon dioxide, and the carbon dioxide condenses at the outlet of the radiator. The difference is that they do not.

[0004] The state of the outlet of the radiator is determined by the discharge pressure of the compressor and the temperature of carbon dioxide at the outlet of the radiator. It is determined by the capacity and the outside air temperature. However, since the outside air temperature cannot be controlled, the temperature of carbon dioxide at the outlet of the radiator cannot be substantially controlled. However, since the state at the outlet of the radiator can be controlled by controlling the discharge pressure of the compressor (the refrigerant pressure at the outlet of the radiator), sufficient cooling capacity (enthalpy difference) can be obtained in summer when the outside air temperature is high. In order to secure (1), the refrigerant pressure at the outlet of the radiator is increased.

Among such decompression devices for controlling the refrigerant pressure at the outlet of the radiator, a pilot decompression device having a piston structure has been proposed (for example, Japanese Patent Application Laid-Open No. 9-26444).
No. 9). According to this type of pilot pressure reducing device, an electric signal (O) corresponding to a target outlet pressure of the radiator is provided.
By transmitting the N / OFF duty ratio signal), the opening degree of the pressure reducing valve is controlled via the piston, so that fine control according to the heat load can be performed.

In a conventional cooling cycle using a chlorofluorocarbon refrigerant, a so-called temperature-sensitive expansion valve that controls the opening of a pressure reducing valve by sensing the outlet temperature of an evaporator is used.
As described above, in the cooling cycle using carbon dioxide or the like as the refrigerant, the refrigerant pressure in the cycle is 3.5 to 10 MPa, which is significantly higher than that of the conventional Freon system (0.2 to 1.6 MPa). The pressure resistance of the diaphragm constituting the temperature-sensitive expansion valve becomes a problem. Further, carbon dioxide and the like are unsuitable as a temperature-sensitive refrigerant because they are gases at the temperature in the cycle. For these reasons, pilot-type pressure reducing devices are mainly used in cooling cycles using carbon dioxide or the like as a refrigerant.

[0007]

However, the conventional pilot-type pressure reducing device having a piston structure has a structure in which a refrigerant flow path from a radiator to an evaporator communicates with a cylinder chamber formed in the pressure reducing device main body. Therefore, dust such as iron powder contained in the refrigerant may adhere to the sliding surface of the piston, and cause malfunction of the piston, that is, malfunction of opening and closing of the pressure reducing valve. Further, in the conventional piston type pressure reducing device having a piston structure, since the refrigerant pressure from the radiator to the evaporator acts directly on the back surface of the piston, the opening and closing of the pressure reducing valve due to the fluctuation of the dynamic pressure. The differential pressure control by the operation becomes unstable.

The present invention has been made in view of the above-mentioned problems of the prior art, and prevents dust from adhering to a sliding surface of a piston, and makes a difference regardless of fluctuations in dynamic pressure acting on the piston. It is an object of the present invention to provide a cooling cycle pressure reducing device capable of stabilizing pressure control.

[0009]

In order to achieve the above object, a pressure reducing device (3) according to the present invention comprises a refrigerant flow path (319, 32) between a refrigerant inlet (314) and a refrigerant outlet (315).
0) a housing (311, 312, 313) having a decompression hole (316), a cylinder chamber (322) communicating with the refrigerant flow path, and a control fluid inlet (326) communicating with the cylinder chamber. A piston (323) provided in the cylinder chamber; and a valve (317) connected to the piston to open and close the pressure reducing hole, at least from the control fluid inlet to one end surface of the piston. In a pressure reducing device for controlling an opening degree of a pressure reducing hole by the valve body by a differential pressure between a working fluid pressure and a refrigerant pressure acting on the other end surface of the piston, the refrigerant flow path (320) in the housing and the refrigerant flow path (320) A shielding wall (36) is provided between the other end surface of the piston and the piston.

In the decompression device of the present invention, since the shielding wall is provided between the refrigerant flow path and the other end face of the piston, the refrigerant passing through the refrigerant flow path is directly transmitted to the other end face of the piston by the shielding wall. It can be prevented from trying to flow into the side. This prevents dust contained in the refrigerant from adhering to the sliding surface of the piston of the cylinder, thereby preventing malfunction of the piston. In addition, since it is possible to prevent the refrigerant pressure in the refrigerant flow passage from acting on the other end surface of the piston, even if the dynamic pressure of the refrigerant fluctuates, the operation of the piston, and hence the opening and closing operation of the pressure reducing valve, may become unstable. Absent.

[0011] In the decompression device of the present invention, the specific configuration of the shielding wall is not particularly limited, but can be configured by a bellows (see Fig. 3).

When the shielding wall is formed of a bellows, it is more preferable to provide a back pressure release flow path (37) for communicating one end side of the piston with a downstream side of the pressure reducing hole of the refrigerant flow path. (See FIG. 3).

[0013] A first back pressure release flow path (372) is formed in the piston so that the one end side and the other end side of the piston communicate with each other. A second back pressure release channel (371) for communicating with the refrigerant channel may be formed (see FIG. 2).

In this case, the second back pressure relief flow path may be constituted by a gap between the other end face of the piston and the refrigerant flow path (see FIGS. 4 and 5).

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing an example of a cooling cycle to which the pressure reducing device of the present invention is applied, FIG. 2 is a sectional view showing an embodiment of the pressure reducing device of the present invention, and FIG. 6 is for explaining a cooling cycle of carbon dioxide refrigerant. FIG.

First, the structure of the cooling cycle shown in FIG. 1 will be described. In the cooling cycle according to the present embodiment, a compressor 1, a radiator 2, a pressure reducing device 3, an evaporator 4, and an accumulator 5 are arranged in this order by a refrigerant pipe. 8 connected by
A closed circuit is configured.

The compressor 1 obtains a driving force from an engine or the like (not shown), compresses the carbon dioxide refrigerant in a gaseous state, and discharges the refrigerant toward the radiator 2. The radiator 2 cools the carbon dioxide refrigerant compressed by the compressor 1 by exchanging heat with the outside air or the like. In order to promote the heat exchange or to allow the heat exchange even when the vehicle is stopped, the radiator 2 is cooled. A fan 6 is added. The radiator 2 is disposed, for example, on the front of a vehicle in order to maximize the difference between the temperature of the carbon dioxide refrigerant in the radiator 2 and the outside air temperature.

The decompression device 3 decompresses the high-pressure (about 10 MPa) carbon dioxide refrigerant flowing out of the radiator 2 by passing it through the decompression holes 316, which will be described later. The decompression device 3 has a function of controlling the pressure on the outlet side of the radiator 2 while decompressing the carbon dioxide refrigerant, and the carbon dioxide refrigerant decompressed by the decompression device 3 is in a gas-liquid two-phase state. And flows into the evaporator (heat absorber) 4.

The evaporator 4 is for cooling the air blown into the vehicle interior. For example, the evaporator 4 is built in the casing of an air-conditioning unit mounted on the vehicle. 4, the intake air is cooled, and is blown out to a desired position in the vehicle compartment through an outlet (not shown). That is, the gas-liquid two-phase carbon dioxide refrigerant flowing down from the pressure reducing device 3 is:
When evaporating (vaporizing) in the evaporator 4, it takes in latent heat of evaporation from the intake air to cool it.

The accumulator 5 separates the carbon dioxide refrigerant passing through the evaporator 4 into a gaseous state refrigerant and a liquid state refrigerant, and sends only the gaseous state refrigerant to the compressor 1 and the liquid phase refrigerant. The refrigerant in the state is temporarily stored.

Next, the pressure reducing device 3 will be described in detail. The decompression device 3 of the present embodiment includes a decompression device main body 31 for decompressing the high-pressure refrigerant from the radiator 2 and an opening control for controlling the opening of the decompression holes 316 provided in the decompression device main body 31. And an apparatus 34.

The pressure reducing device main body 31 is assembled by screwing the housing 312 and the housing 313 into the housing 311. The housing 313 has a refrigerant inlet 314 through which high-pressure refrigerant from the radiator 2 flows. A refrigerant outlet 315 through which the depressurized refrigerant flows toward the evaporator 4 is formed.

In the housing 311 between the refrigerant inlet 314 and the refrigerant outlet 315, refrigerant passages 319 and 320 are formed, and a decompression hole 316 forming a bottleneck between the refrigerant passages 319 and 320 is provided. I have. This decompression hole 3
16 is provided with a valve element 317 on the refrigerant flow path 319 side, and is connected to a piston 323 to be described later via a rod 321 to open and close the pressure reducing hole 316 at a predetermined opening. “318” shown in FIG. 2 is a coil spring, which urges the valve body 317 in the closing direction of the pressure reducing hole 316.
The opening / closing operation of the pressure reducing hole 316 by the valve element 317 will be described later.

On the other hand, the piston 3
A cylinder 322 into which the piston 23 is inserted is formed, and a control fluid inlet 326 is formed in an upper portion of FIG. 2 (hereinafter, also referred to as a top surface side of the piston). A working fluid (in this embodiment, a carbon dioxide refrigerant circulating in the cooling cycle is used) is introduced into the top surface side space 325 of the piston 323. A coil spring 324 that biases the piston 323 downward is provided in the top surface side space 325, and the valve body 317 closes the pressure reducing hole 316 in a no-load state by balancing with the coil spring 318 described above. I do.

The back pressure acting on the top side space 325 is released from the piston 323 itself,
A back pressure release channel 37 is formed in order to improve the operation of. The back pressure release channel 37 of the present embodiment is
3 and a second back pressure release channel 371 formed in the shielding wall 36 described later. The control flowed into the top side space 325 of the piston 323. Fluid (carbon dioxide refrigerant) is used for these first and second fluids.
Through the back pressure relief channels 372 and 371 to reach the coolant channel 320, whereby the piston 323 is connected to the cylinder 3
22 will slide smoothly.

In particular, in the present embodiment, the shielding wall 36 is fixed to the housing 312 at a position facing the coolant passage 320. The shielding wall 36 is provided on the lower surface of the piston 323 (hereinafter, referred to as a piston 323).
Also called the back. ) And the refrigerant flow path 320 are substantially blocked, except for the through hole of the rod 321 and the above-mentioned second back pressure release flow path 371. This shielding wall 3
6 may be fixed to the housing 312 as a separate part, or may be formed integrally with the housing 312.

The opening control device 34 of this embodiment has a housing 341, a control fluid inlet 342 into which the control fluid flows into the housing 341, and a control fluid into which the control fluid flows out toward the pressure reducing device main body 31. A fluid outlet 344 is formed. A valve port 347 as a bottleneck is formed between the control fluid inlet 342 and the outlet 344, and the needle valve 348 is opened and closed so as to open and close the valve port 347.
Is provided.

The needle valve 348 is connected to a plunger 350, and the plunger 350
The fine opening / closing of the valve port 347 by the needle valve 348 per unit time (duty ratio of opening and closing) is controlled by finely moving forward and backward by the magnetic field from FIG.

In the present embodiment, the carbon dioxide refrigerant itself circulating in the cooling cycle is used as the control fluid. The control fluid is supplied from a control fluid outlet 327 provided in the housing 311 of the decompression device main body 31. It is introduced into the control fluid inlet 342 via the pipe 343, and further from the control fluid outlet 344 via the pipe 345.
One control fluid inlet 326 is introduced.

Next, the operation of the cooling cycle of this embodiment will be described with reference to the Mollier diagram of FIG. First, a gaseous carbon dioxide refrigerant is compressed by the compressor 1 (A-B),
The high-temperature and high-pressure gas-phase carbon dioxide refrigerant is cooled by the radiator 2 (BC). After the pressure is reduced by the pressure reducing device 3 (CD), the carbon dioxide refrigerant in the gas-liquid two-phase state is evaporated by the evaporator 4 (DA), and the latent heat of evaporation is removed from the incoming air. Cool it. Thereby, the intake air introduced into the unit of the air conditioner is cooled, and is blown out into the vehicle interior to cool the vehicle interior.

The carbon dioxide refrigerant that has passed through the evaporator 4 is separated into gas and liquid by the accumulator 5, and only the refrigerant in the gaseous state is sucked into the compressor 1 again.

In the depressurization process of CD in the Mollier diagram, the following control is executed according to the heat load on the evaporator 4.

That is, when the heat load is high (when a large amount of cooling is required), such as in summer, a large amount of refrigerant needs to be supplied from the pressure reducing device 3 to the evaporator 4. In order to increase the opening degree, the duty ratio of the needle valve 348 of the opening degree control device 34 is increased (the opening time ratio is increased). Thereby, the control fluid outlet 3
27 to piping 343, 345 and control fluid inlet 32
6, the high-pressure refrigerant is introduced into the space 325 on the top surface side of the piston 323, so that the piston 323 is pressed downward in FIG. 2. As a result, the valve body 317 also moves downward via the rod 321. , The pressure reducing hole 316 is opened. On the other hand, when the heat load is not so large, the duty ratio by the needle valve 348 of the opening control device 34 is reduced, and the amount of the refrigerant introduced into the space 325 on the top surface side of the piston 323 is reduced. Thereby, the piston 323
Moves upward in FIG. 2, and accordingly, the valve element 317
Also moves upward, and the degree of opening of the pressure reducing hole 316 decreases.

When the piston 323 moves upward from the lower position, the space 325 on the top surface side of the piston 323 moves.
Is introduced into the refrigerant channel 320 via the first back pressure releasing channel 372 and the second back pressure releasing channel 371, so that the operation of the piston 323 is performed smoothly.

At this time, when the valve element 317 opens the pressure reducing hole 316, high-pressure refrigerant flows from the radiator 2 into the refrigerant channels 319, 320 of the pressure reducing device main body 31, and this refrigerant pressure is applied to the rear side of the piston 323. However, in the present embodiment, since the shielding wall 36 is provided here, it is suppressed that the high-pressure refrigerant directly acts on the back side of the piston 323. This can prevent dust such as iron powder contained in the refrigerant from adhering to the cylinder 322 and biting between the piston 323 and causing malfunction of the piston 323. In addition, the high-pressure refrigerant has the piston 323
Does not directly act on the rear surface of the piston 323, thereby making it possible to avoid instability of the vertical movement of the piston 323.

The decompression device of the present invention is not limited to the above-described embodiment, but can be variously modified and modified. 3 to 5 are main-portion cross-sectional views showing other embodiments of the pressure reducing device of the present invention.

In the embodiment shown in FIG. 3, a bellows 36 is employed as a shielding wall according to the present invention. Further, as the back pressure release flow path according to the present invention, a back pressure release flow path 37 that directly communicates from the space 325 on the top surface side of the piston 323 to the refrigerant outlet 315 is employed.

In the embodiment shown in FIG. 4, the location of the shielding wall 36 according to the present invention is substantially at the level of the center of the refrigerant outlet 315, so that the space between the shielding wall 36 and the refrigerant outlet 315 is provided. Since a gap is generated, in this example, the shielding wall 3 is used.
It is not necessary to provide the second back pressure release channel 371 in FIG.

In the embodiment shown in FIG. 5, the shielding wall 36 is positioned slightly above the position where the shielding wall 36 is disposed in FIG. Is formed as a notch at the end of the shielding wall 36.

In the modified examples shown in FIGS. 3 to 5, the same operation and effect as those of the embodiment shown in FIG. 2 are obtained, and the dust contained in the refrigerant adheres to the sliding surface of the piston of the cylinder. The operation of the piston, and thus the opening and closing operation of the pressure reducing valve, does not become unstable even if the dynamic pressure of the refrigerant fluctuates.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

[0042]

As described above, according to the present invention, dust contained in the refrigerant is prevented from adhering to the sliding surface of the piston of the cylinder, and the operation of the piston is improved. Also, even if the dynamic pressure of the refrigerant fluctuates, the operation of the piston,
Consequently, the opening / closing operation of the pressure reducing valve does not become unstable.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an example of a cooling cycle to which a pressure reducing device of the present invention is applied.

FIG. 2 is a cross-sectional view showing an embodiment of the pressure reducing device of the present invention.

FIG. 3 is a sectional view of a main part showing another embodiment of the pressure reducing device of the present invention.

FIG. 4 is a sectional view of a main part showing still another embodiment of the pressure reducing device of the present invention.

FIG. 5 is a sectional view of a main part showing still another embodiment of the pressure reducing device of the present invention.

FIG. 6 is a Mollier diagram for explaining a cooling cycle of carbon dioxide refrigerant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Compressor 2 ... Radiator 3 ... Decompression device 31 ... Decompression device main body 311, 312, 313 ... Housing 314 ... Refrigerant inlet 315 ... Refrigerant outlet 316 ... Decompression hole 317 ... Valve element 319,320 ... Refrigerant flow path 322 ... Cylinder 323 Piston 325 Top-side space 326 Control fluid inlet 34 Opening degree control device 36 Shield wall 37 Back pressure release channel 4 Evaporator 5 Accumulator 6, 7 Fan 8 Coolant piping

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Torahide Takahashi 5-24-15 Minamidai, Nakano-ku, Tokyo Calsonic Co., Ltd. (72) Inventor Yusuke Inoue 1211-4 Nugita-cho, Hachioji-shi, Tokyo F-term in TOKYO K (reference) 3H056 AA01 BB41 CA01 CB03 CB06 CB09 CC12 CD03 CE01 GG03 GG13 3H059 AA06 BB06 CD04 CE04 CF14 EE01 FF15

Claims (5)

[Claims] A housing having a pressure reducing hole formed in a refrigerant flow passage between a refrigerant inlet and a refrigerant outlet, a cylinder chamber communicating with the refrigerant flow passage, and a control fluid inlet communicating with the cylinder chamber. A piston provided in the cylinder chamber; a valve connected to the piston to open and close the pressure reducing hole; and a fluid pressure acting on at least one end face of the piston from the control fluid inlet and the piston. A depressurizing device that controls an opening degree of a depressurizing hole by the valve body by a differential pressure between the refrigerant pressure acting on the other end face of the piston, and a shielding wall between the refrigerant flow path in the housing and the other end face of the piston. Is provided. 2. The pressure reducing device according to claim 1, wherein said shielding wall is a bellows. 3. A back pressure release flow path for communicating one end surface of said piston with a downstream side of said pressure reducing hole of said refrigerant flow path is provided. Decompression device. 4. A first back pressure relief flow path for communicating one end face and the other end face of the piston with the piston, and the other end face of the piston and the refrigerant flow are formed on the shielding wall. 2. The pressure reducing device according to claim 1, wherein a second back pressure release flow path communicating with the path is formed. 5. The pressure reducing device according to claim 4, wherein the second back pressure release flow path is a gap between the other end surface of the piston and the refrigerant flow path.