AIR-CONDITIONING SILENCING DEVICE

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2024-112643 filed on Jul. 12, 2024, incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The present specification discloses an air-conditioning silencing device incorporated in an in-vehicle air-conditioning device.

2. Description of Related Art

Conventionally, it has been proposed to provide an in-vehicle air-conditioning device with a silencing device, in order to suppress pulsation of an air-conditioning refrigerant. For example, Japanese Patent No. 6104256 discloses a structure in which a muffler is disposed in the vicinity of a compressor. In Japanese Patent No. 6104256, one end of the muffler is bolted to the compressor, and the other end of the muffler is supported by a bracket.

While fluorine-based refrigerants were used as air-conditioning refrigerants in the past, use of different types of refrigerants has been studied in recent years. For example, use of carbon dioxide (hereinafter referred to as “CO2”) as an air-conditioning refrigerant has been proposed by some people. CO2 refrigerants have a lower global warming potential than the fluorine-based refrigerants. On the other hand, the CO2 refrigerants need to be pressurized to a higher pressure than the fluorine-based refrigerants.

SUMMARY

The technique of Japanese Patent No. 6104256 does not assume the use of a high-pressure CO2 refrigerant, and it is difficult to apply the technique to an air-conditioning device that uses a CO2 refrigerant. In particular, since the CO2 refrigerant is pressurized to a high pressure, the muffler is also required to have a high pressure resistance. The muffler disclosed in Japanese Patent No. 6104256 has room for improvement in such pressure resistance.

Conventionally, the muffler is often formed by drawing. When the muffler is formed by drawing, however, the wall thickness of the muffler cannot be increased. As a result, it has not been possible to manufacture a muffler having a high pressure resistance by drawing.

Accordingly, the present specification provides an air-conditioning silencing device that enables use of a CO2 refrigerant.

An aspect of the present specification provides an air-conditioning silencing device provided in a pipe for an air-conditioning refrigerant containing carbon dioxide (CO2), the air-conditioning silencing device including a muffler body including: a cylindrical body having no seam in a circumferential direction; and a pair of lid bodies airtightly welded to both axial ends of the cylindrical body so as to close openings at both the axial ends of the cylindrical body.

Since the muffler body has a welded structure, the wall thickness of the muffler body can be increased. This allows the muffler body to receive a high-pressure CO2 refrigerant.

In this case, the cylindrical body may have a wall thickness of more than 4 mm.

With such a wall thickness, a high-pressure CO2 refrigerant can be received. It is generally said that drawing supports a wall thickness of up to 3 mm. In the configuration described above, however, the muffler body is formed by welding instead of drawing, and thus can have a wall thickness of 4 mm.

The muffler body may further include a punching separator disposed in an internal space of the cylindrical body to axially divide the internal space and formed with a plurality of through holes.

With such a configuration, it is possible to more effectively suppress the pulsation of the pressure of the refrigerant.

The silencing device may further include: an inlet pipe that leads the refrigerant to the muffler body; and

• • an outlet pipe that leads the refrigerant downstream from the muffler body, and
  • the inlet pipe and the outlet pipe may be joined to the muffler body by brazing.

Consequently, the manufacturing cost of the silencing device can be reduced. That is, the pressure load on the joint between the pipe and the muffler body is lower than that on the joint between the cylindrical body and the lid body. The manufacturing cost can be reduced by brazing such a portion where the pressure load is low.

The cylindrical body may have a cylindrical shape with a constant outside diameter.

With such a configuration, the cylindrical body can be manufactured by a simple low-cost manufacturing method such as extrusion. As a result, the cost of the silencing device can be reduced.

According to the air-conditioning silencing device disclosed in the present specification, it is possible to use a CO2 refrigerant.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein:

FIG. 1 is a diagram illustrating a configuration of an air conditioner;

FIG. 2 is a perspective view of the muffler periphery;

FIG. 3 is a cross-sectional perspective view of a muffler body;

FIG. 4 is a cross-sectional exploded view of another muffler body; and

FIG. 5 is a cross-sectional view of another muffler body.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, the silencing device 50 for an in-vehicle air conditioner will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating a configuration of an air conditioner 10. The air conditioner 10 is mounted on a vehicle and adjusts the temperature of the vehicle cabin. The type of the vehicle on which the air conditioner 10 is mounted is not particularly limited. Therefore, the vehicle may be an engine vehicle using an engine as a power source or a battery electric vehicle using a motor as a power source. In addition, vehicles may be hybrid-type battery electric vehicle equipped with both engines and motors. The vehicles may be fuel cell electric vehicle equipped with fuel-cells. The vehicles may be battery electric vehicle that travel with electric power stored in batteries.

The air conditioner 10 includes a refrigerant circuit 12. The refrigerant circuit 12 generates heat and latent heat by compressing, expanding, condensing, and evaporating the refrigerant in the process of circulating the refrigerant. Heat generated in the refrigerant circuit 12 is used for heating, and latent heat is used for cooling. Heretofore, a fluorine-based refrigerant has been frequently used as the refrigerant. However, there is a problem that the fluorine-based refrigerant has a high load on the environment. Therefore, in the present embodiment, a CO2 coolant containing CO2 as a main component is employed. CO2 refrigerants have lower global warming potential and lower environmental impact than fluorine-based refrigerants. On the other hand, CO2 refrigerant needs to be used at a higher pressure than the fluorine-based refrigerant. For example, fluorine-based refrigerants are utilized in the pressure range of 0.02 MPaG to 2 MPaG, while CO2 refrigerants are utilized in the pressure range of 0.8 MPaG to 10 MPaG. Therefore, devices that handle CO2 refrigerants are required to have high-voltage resistance.

The refrigerant circuit 12 includes a refrigerant pipe 14 through which CO2 refrigerant flows. A compressor 16, a condenser 18, an accumulator 20, a cooling expansion valve 42, and an evaporator 22 are provided in the middle of the path of the refrigerant pipe 14. The compressor 16 compresses the gaseous CO2 coolant. As described above, CO2 refrigerant needs to be pressurized to a higher pressure than the fluorine-based refrigerant. In order to satisfy such pressure requirements, the compressor 16 is selected to have a large power and a large size.

The condenser 18 is a heat exchanger that exchanges heat between CO2 coolant and the outside air. The condenser 18 functions as a condenser that condenses the gaseous CO2 coolant during the cooling operation. A condenser fan 19 for efficiently taking in outside air is disposed behind the condenser 18.

The accumulator 20 gas-liquid separates CO2 refrigerant and sends only the gaseous CO2 refrigerant to the compressor 16. In the example of FIG. 1, the accumulator 20 includes a heat exchanger.

The cooling expansion valve 42 is a solenoid valve that is throttle-controlled during a cooling operation and is completely closed during a heating operation. When the cooling expansion valve 42 is throttled, CO2 coolant is rapidly reduced in pressure when passing through the cooling expansion valve 42. The evaporator 22 is an evaporator for evaporating the liquid CO2 coolant, and is disposed in a flow path of the air-conditioned air provided in the unit case 30. The latent heat generated during evaporation cools the air around the evaporator 22.

Although not shown in FIG. 1, the refrigerant circuit 12 is provided with several solenoid valves for switching the direction in which the air-conditioning refrigerant flows. Further, the refrigerant circuit 12, a plurality of PT sensors 44 for detecting the pressure and temperature of CO2 refrigerant flowing through the refrigerant pipe 14 are arranged.

A blowing mechanism 28 is disposed in the vehicle cabin. The blowing mechanism 28 is a mechanism that cools or heats air taken in from the outside or the inside of the vehicle and blows the air into the vehicle. The blowing mechanism 28 includes a unit case 30, a blower fan 32, and a heater core 33. The downstream end of the unit case 30, the air outlet (not shown) for guiding the air conditioning air into the vehicle is formed. Further, an evaporator 22 and a heater core 33 are disposed in the unit case 30. During the cooling operation, the evaporator 22 cools the air sent from the blower fan 32 by the latent heat when the air-conditioning refrigerant is vaporized. The cooled air-conditioned air is output to the interior of the vehicle, thereby cooling the interior of the vehicle.

The heater core 33 is heated by another heat source during the heating operation. The other heat source may be, for example, an engine or an electric heater. The heater core 33 is heated directly by another heat source or indirectly through a refrigerant such as water. A mode switching door 36 is disposed upstream of the heater core 33. The mode switching door 36 adjusts the amount of air passing through the heater core 33. During the heating operation, the mode switching door 36 moves to a position where the wind toward the heater core 33 is not blocked (a position indicated by a broken line in FIG. 1). As a result, the air sent from the blower fan 32 passes through the heater core 33 and is heated. The heated air-conditioned air is output to the inside of the vehicle, thereby heating the vehicle cabin.

The air conditioner 10 is further provided with a silencing device 50. The silencing device 50 is disposed in the middle of the refrigerant pipe 14 connecting the compressor 16 and the condenser 18. The silencing device 50 suppresses the noise caused by the pulsation of CO2 coolant and thus the pulsation. The silencing device 50 includes a muffler body 52 that attenuates sound by expanding gaseous CO2 coolant. Here, CO2 coolant is pressurized downstream of the compressor 16. By disposing the silencing device 50 downstream of the compressor 16, it is possible to more efficiently silence the sound.

Since the operation of the air conditioner 10 is known in the art, detailed description thereof will be omitted. The configuration of the air conditioner 10 shown in FIG. 1 is an example. Other configurations of the air conditioner 10 may be changed as long as the air conditioner includes the compressor 16, the condenser 18, and the silencing device 50. Therefore, for example, the air conditioner 10 may further include a battery cooling circuit or the like for cooling electronic devices such as a battery and a fuel cell.

As shown in FIG. 2, the silencing device 50 (muffler body 52) is attached to the condenser 18. As shown in FIGS. 2 and 3, the muffler body 52 is a substantially cylindrical tubular member. The muffler body 52 is fluidly connected to the compressor 16 and the condenser 18 via a refrigerant pipe 14.

The diameter of the muffler body 52 is sufficiently larger than the diameter of the refrigerant pipe 14. Therefore, CO2 refrigerant flows into the muffler body 52 from the refrigerant pipe 14 and rapidly expands. This expansion attenuates the sound-energy of CO2 refrigerant and suppresses the pulsation of CO2 refrigerant.

As shown in FIG. 3, the muffler body 52 has an elongated shape having an axial dimension larger than a diameter. For example, the axial dimension of the muffler body 52 is not less than twice or not less than five times its diameter. The muffler body 52 is disposed adjacent to the condenser 18 in the vehicle width direction in an upright posture in which the axial direction thereof is substantially parallel to the vehicle vertical direction. By arranging the elongated muffler body 52 in the upright posture as described above, the muffler body 52 can also be arranged in a small gap, and the space efficiency of the vehicle is improved.

The muffler body 52 includes a cylindrical body 54 and a pair of lid bodies 56. Each of the cylindrical body 54 and the lid body 56 is made of metal, for example, stainless steel, carbon steel, or the like. Further, the cylindrical body 54 has a cylindrical shape without a seam in the circumferential direction. The wall thickness t of the cylindrical body 54 is equal to or larger than 4 mm, and is, for example, 5 mm. The cylindrical body 54 has a constant outer diameter. Therefore, the cylindrical body 54 can be manufactured by a simple manufacturing method at low cost such as extrusion molding.

The lid body 56 is a disk-shaped member that closes an opening at an axial end portion of the cylindrical body 54. Similarly to the cylindrical body 54, the thickness t of the lid body 56 is equal to or larger than 4 mm, and is, for example, 5 mm. The lid body 56 is airtightly welded to the axial end of the cylindrical body 54 by welding. For example, the joint between the lid body 56 and the cylindrical body 54 is welded, for example, arc-welded, over the entire circumference. As is well known, welding is a technique in which the base material itself is melted and joined at a high temperature.

A pipe hole is formed in the center of the lid body 56, and the inlet pipe 60 or the outlet pipe 62 is joined to the pipe hole. The inlet pipe 60 is a pipe that guides CO2 coolant from the compressor 16 to the muffler body 52. In this example, the inlet pipe 60 is joined to the upper lid body 56. The outlet pipe 62 is a pipe that guides CO2 coolant from the muffler body 52 to the condenser 18. In this example, the outlet pipe 62 is joined to the lower lid body 56.

Both the inlet pipe 60 and the outlet pipe 62 are joined to the lid body 56 by brazing. Brazing is, as is well known, a technique in which, between two base materials to be bonded, the melted braze is dropped, and then the braze is solidified to join the two base materials. Such brazing does not melt the base material, so that deformation of the base material can be suppressed as compared with welding. In addition, the brazing can join the two members at a lower cost than the welding.

CO2 coolant guided to the muffler body 52 through the inlet pipe 60 rapidly expands inside the muffler body 52. This attenuates the noise and reduces the pulsation of CO2 coolant. The expanded CO2 coolant is outputted to the condenser 18 via the outlet pipe 62.

A punching separator 58 is disposed inside the cylindrical body 54. The punching separator 58 is a disk having a plurality of holes formed therein. The diameter of the punching separator 58 is substantially the same as the diameter of the cylindrical body 54. Therefore, the inner space of the cylindrical body 54 is divided in the axial direction by the punching separator 58. As CO2 coolant passes through the punching separator 58, the sound-energy of CO2 coolant is further attenuated. As a result, pulsation of CO2 coolant is more effectively prevented. The punching separator 58 may be joined to the cylindrical body 54 by welding or brazing.

Incidentally, the conventional muffler body for air conditioning is manufactured by drawing. Drawing is a type of press working for producing a cylindrical shape by applying pressure to a metal plate. Such drawing has the advantage of low cost. On the other hand, since the thin plate is deformed by drawing, a cylindrical shape having a large wall thickness cannot be obtained by drawing. Generally, in drawing, the wall thickness is limited to 3 mm or less, although it depends on the materials and shapes. Therefore, in the drawing process, the muffler body having high pressure resistance cannot be manufactured. On the other hand, as described above, CO2 refrigerant has a high pressure, and when CO2 refrigerant is used, the muffler body 52 is required to have a high pressure resistance. Therefore, the muffler body 52 for CO2 coolant cannot be manufactured by drawing.

Therefore, as described above, the muffler body 52 of the present example is configured by welding the lid body 56 to the cylindrical body 54. With this configuration, the wall thickness of the cylindrical body 54 and the lid body 56 can be increased, and the pressure resistance of the muffler body 52 can be increased. Thus, the muffler body 52 capable of receiving the high-pressure CO2 coolant is obtained.

As described above, in the present example, the joint between the cylindrical body 54 and the lid body 56 is welded, but the joint between the lid body 56 and the inlet pipe 60 or the outlet pipe 62 is brazed. This is to reduce the manufacturing cost of the muffler body 52. That is, in general, the joint between the lid body 56 and the pipes 60 and 62 has a smaller pressure load than the joint between the cylindrical body 54 and the lid body 56. By brazing a portion where the pressure load is small, the manufacturing cost can be reduced.

In addition, any of the configurations described above is an example, and other configurations may be changed as appropriate as long as the configuration described in claim 1 is provided. For example, the inlet pipe 60 and the outlet pipe 62 may be joined to the peripheral surface of the cylindrical body 54 instead of the lid body 56. In addition, the pipes 60 and 62 may be joined to the lid body 56 or the cylindrical body 54 by welding instead of brazing. The punching separator 58 may be omitted. Further, another member may be disposed in place of or in addition to the punching separator 58 inside the muffler body 52.

Further, the shape and configuration of the cylindrical body 54 and the lid body 56 may be changed as appropriate. For example, the outer diameter of the cylindrical body 54 may vary along the axial direction, and for example, the cylindrical body 54 may have a cone shape, a barrel shape, a stepped shape, or the like. Further, the cylindrical body 54 may be divided into a plurality in the axial direction. For example, as illustrated in FIG. 4, the cylindrical body 54 may be configured by axially aligning and welding the first cylinder 54a and the second cylinder 54b. By forming the cylindrical body 54 by joining a plurality of short cylinders 54a, 54b as described above, the operation of attaching another member (for example, the punching separator 58) to the inside of the cylindrical body 54 can be facilitated. Further, the cylindrical body 54 is not limited to a circular cross section, and may be an oval cross section or a square cross section.

The lid body 56 is not limited to a flat plate, and may have other shapes. For example, the lid body 56 may have a dome shape as shown in FIG. 5. With this configuration, it is possible to reduce the concentration of pressure at the joint between the cylindrical body 54 and the lid body 56. As a result, the pressure resistance of the muffler body 52 can be further improved.