JPH06221724A - Freezing cycle - Google Patents

Abstract

PURPOSE:To provide a freezing cycle in which, even if a temperature sensing cylinder part is made to have subcooling in a control of the subcooling of a refrigerant condenser in which a heat exchanging part forms a layered structure with respect to a flow of cooling medium, a rising of high temperature and an increase of refrigerant pressure can be minimized, and also cycle performance can stabilized. CONSTITUTION:In an indoor condenser 14, a heat exchanging part is formed of a first core part 14a, a seond core part 14b and a third core part 14c, and all these core parts 14a to 14c, with the second core part 14b placed between the other two, form a three-layered structure, where the first core part 14a which forms an upstream side of a refrigerant flowing direction is arranged in the air downstream inside a duct 2, while the third core part 14c which forms a downstream side is arranged in the air upstream inside the duct 2. A subcooling control valve 19 is formed of a valve body 19a provided in the downstream of the indoor condenser 14 and a temperature sensing cylinder 19b which is in contact with a bypass pipe 14d interposed in the third core part 14c. It is designed that some amount of subcooling is carried out at a position where the bypass pipe 14d contacts with the temperature sensing cylinder 19b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle equipped with a supercooling degree control valve for controlling the degree of supercooling of high-pressure refrigerant (hereinafter referred to as "subcool"), and is particularly suitable for use in a vehicle air conditioner. is there.

[0002]

2. Description of the Related Art FIG. 6 shows an example of an indoor unit portion of a conventional air conditioner for an electric vehicle. This indoor unit is located in the duct 100 downstream of the indoor evaporator 101 (downwind).
The indoor condenser 102 arranged in the
A subcool control valve (described later) for controlling the subcool therein is provided. The indoor condenser 102 is used as a heat exchanger for heating, and has a layered structure with respect to the flow of air flowing in the duct 100.
It has a heat exchange part 102b and a third heat exchange part 102c, and the first heat exchange part 102a on the upstream side in the flow direction of the refrigerant is arranged on the most leeward side in the flow direction of the air and on the downstream side in the flow direction of the refrigerant. The third heat exchange unit 102c is arranged on the most windward side in the air flow direction. The subcool control valve includes a valve body 103 provided downstream of the indoor condenser 102, a second heat exchange section 102b, and a third heat exchange section 102.
The temperature sensing cylinder 104 is in contact with the refrigerant pipe connecting to c
Based on the pressure change in the temperature sensing cylinder 104, the valve body 103 is controlled so that a subcool is obtained in the third heat exchange section 102c.
The valve opening of is controlled. Note that it is difficult for the subcool control valve to identify the point at which the condensation of the refrigerant ends, that is, the point where subcool = 0, due to the responsiveness of the valve, fluctuations in the refrigerant flow rate, etc. It is set to have a sub-cool of (sub-cool = about 4 ° C).

[0003]

As described above, the temperature sensing tube 1 is used.
Having a slight subcool in 04 copies is the temperature sensitive tube 104
A sub-cool is provided upstream of the part (downstream of the second heat exchange part 102b). However, as shown in FIG. 6, the downstream region of the second heat exchange section 102b upstream of the temperature sensitive tube 104 section is the third heat exchange section 10 downstream of the temperature sensitive tube 104 section.
When it is arranged leeward of the upstream region of 2c, the warm air warmed through the upstream region of the third heat exchange unit 102c hits the downstream region of the second heat exchange unit 102b. Therefore,
In the downstream region of the second heat exchange section 102b, the temperature difference between the refrigerant and the air is small, so a large area is required to take a small amount of subcool. As a result, the indoor condenser 102
As a whole, the heat exchange section in the gas-liquid two-phase region is reduced and the increase in high pressure is increased, so that the cycle efficiency is deteriorated and the required amount of refrigerant is increased. Further, since the high pressure fluctuation and the refrigerant quantity fluctuation are large with respect to the fluctuation of the subcool of the temperature sensitive cylinder 104, the cycle performance becomes unstable. The present invention has been made based on the above circumstances, and an object of the present invention is to provide a temperature-sensitive tubular portion in a case where a heat exchange section controls a subcool of a refrigerant condenser having a layered structure with respect to a flow of a cooling medium. It is to provide a refrigeration cycle in which the increase in high pressure and the increase in the amount of refrigerant are small even if a subcool is provided, and the performance is stabilized.

[0004]

In order to achieve the above object, the present invention comprises, in claim 1, a heat exchange section for condensing and liquefying a passing refrigerant by heat exchange with a cooling medium. The part comprises a first heat exchanging part which constitutes an upstream side of the heat exchanging part and a second heat exchanging part which constitutes a downstream side of the heat exchanging part in the flow direction of the refrigerant, and the first heat exchanging part is the above in the flow direction of the cooling medium. A refrigerant condenser arranged on the downstream side of the second heat exchange section, and a supercooler for adjusting the opening degree of the refrigerant flow path downstream of the refrigerant condenser so as to be in the supercooling region from the middle of the second heat exchange section. The provision of a degree adjusting valve is a technical means. Moreover, in Claim 2, it has a heat exchange part which condenses and liquefies the refrigerant passing therethrough by heat exchange with a cooling medium, and this heat exchange part constitutes the upstream side of the heat exchange part in the flow direction of the refrigerant. The heat exchange section and a second heat exchange section that forms a downstream side, and
A refrigerant condenser in which a heat exchange section is arranged on the downstream side of the second heat exchange section in the flow direction of the cooling medium, and the refrigerant condenser downstream so that the entire area of the second heat exchange section is a supercooling zone. In the refrigeration cycle including a subcooling degree adjusting valve for adjusting the opening degree of the refrigerant flow path of the second heat exchange section, The technical means is arranged so as to be located on the downstream side in the flow direction of the cooling medium in the downstream region of the section.

[0005]

The refrigeration cycle of the present invention according to claim 1 is the second
Since the supercooling zone is controlled from the middle of the heat exchanging section, a supercooling zone and a gas-liquid two-phase zone are formed in the second heat exchanging section. Since the second heat exchange part is arranged upstream of the first heat exchange part in the flow direction of the cooling medium, the subcooling region and the gas-liquid two-phase region are different from the first heat exchange part in the refrigerant. The temperature difference between the cooling medium and the cooling medium can be made large. Also,
In the refrigeration cycle of the present invention according to claim 2, the downstream region of the first heat exchange unit is located on the downstream side in the flow direction of the cooling medium in the downstream region of the second heat exchange unit. Therefore, in the downstream region of the first heat exchange unit, the cooling medium that has exchanged heat with the refrigerant in the downstream region of the second heat exchange unit flows. Here, in the second heat exchange section serving as the supercooling zone, the refrigerant temperature in the upstream zone is higher than that in the downstream zone, so that the cooling medium heat-exchanged with the refrigerant in the second heat exchange zone is the second heat exchange zone. The temperature rise is smaller on the downstream side than on the upstream side. As a result, the temperature difference between the refrigerant and the cooling medium should be made larger than that in the case where the downstream region of the first heat exchange unit is located on the downstream side in the flow direction of the cooling medium in the upstream region of the second heat exchange unit. You can

[0006]

According to the refrigeration cycle of the present invention, the temperature difference between the refrigerant and the cooling medium can be made large in the heat exchange section upstream of the temperature-sensing cylinder even when the temperature-sensing cylinder is controlled to have a subcool. Therefore, it is possible to reduce the area of the heat exchanging portion required to have the subcool upstream of the temperature-sensitive tubular portion.
As a result, it is possible to prevent an increase in the high pressure due to a decrease in the heat exchange portion in the gas-liquid two-phase region and an increase in the amount of the refrigerant due to an increase in the liquid region, and it is possible to improve the stability of the cycle performance against the subcool fluctuation.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a vehicle air conditioner using the refrigerating cycle of the present invention will be described with reference to FIGS.
FIG. 1 is an overall schematic diagram of a vehicle air conditioner. This vehicle air conditioner 1 is installed in an electric vehicle, and has a duct 2 for introducing blown air into the passenger compartment, a blower 3 for introducing air into the duct 2 and sending the air into the passenger compartment, and an accumulator refrigeration cycle 4. Equipped with. The duct 2 is provided with the inside air introduction ports 5 and 6 and the outside air introduction port 7 at its upstream end, and the introduced air amount of the inside air introduction port 5 and the outside air introduction port 7 is adjusted by the inside and outside air damper 8. At the downstream end of the duct 2, a defroster outlet 9 that discharges blast air toward the windshield of the vehicle, a face outlet 10 that discharges blast air toward the upper half of the occupant, and a blast air toward the feet of the occupant. The foot outlet 11 is connected to. Each outlet 9-1
1 is selectively opened and closed by a damper 12 that operates according to the outlet mode and an outlet damper (not shown).
In the duct 2, an indoor evaporator 13 and an indoor condenser 14 of the refrigeration cycle 4 are arranged, and a cold air bypass passage 15 for bypassing the indoor condenser 14 and flowing. The cold air bypass passage 15 is provided with a bypass damper 16 that opens the cold air bypass passage 15 during the cooling operation and closes the cold air bypass passage 15 during the heating operation in association with the cooling and heating mode.

The refrigeration cycle 4 includes the above-mentioned indoor evaporator 13
In addition to the indoor condenser 14, a refrigerant compressor 17, an outdoor heat exchanger 18, a subcool control valve 19, a pressure reducing device 20, an accumulator 21, and a flow path switching means (described later) are provided. The indoor evaporator 13 is arranged in the duct 2 and cools the passing air by heat exchange with a low-temperature, low-pressure refrigerant. The indoor condenser 14 is arranged in the duct 2 at the lee side of the indoor evaporator 13, and heats the passing air by heat exchange with a high-temperature, high-pressure refrigerant. In addition, this indoor condenser 14
The heat exchanging portion for exchanging heat between the refrigerant and the blown air is divided into the first core portion 14a, the second core portion 14b, and the third core portion 14c, and the respective core portions 14a to 14c are arranged inside the duct 2. The first core portion 14a, which is the upstream side in the flow direction of the refrigerant, is arranged on the leeward side in the duct 2 and the downstream side so as to be a counterflow to the flowing blast air. The 3rd core part 14c which comprises consists of the 3 layer structure distribute | arranged to the windward inside the duct 2 (refer FIG. 2). The refrigerant compressor 17 is a hermetic compressor that incorporates an electric motor (not shown) for driving, and the refrigerant discharge amount changes according to the rotation speed of the electric motor. The outdoor heat exchanger 18 is located outside the duct 2 (outside the passenger compartment).
Are arranged in the air conditioner to perform heat exchange between the outside air and the refrigerant, and by receiving the air blown from the outdoor fan 22, function as a refrigerant evaporator during heating operation and as a refrigerant condenser during cooling operation.

The subcool control valve 19 is used for the indoor condenser 14
Of the valve body 19a provided on the downstream side of the valve core 19a and the temperature sensitive tube 19b contacting the bypass pipe 14d provided in the middle of the third core portion 14c. The valve opening is adjusted. In the present embodiment, it is set so as to have a slight subcool (subcool = about 4 ° C.) at the portion where the temperature sensitive cylinder 19b comes into contact. The decompression device 20 decompresses and expands the refrigerant flowing into the indoor evaporator 13 during the cooling operation. In this embodiment, a capillary tube is used. The accumulator 21 temporarily stores the excess refrigerant in the refrigeration cycle 4 and sends out only the gas-phase refrigerant to the refrigerant compressor 17 to prevent the liquid refrigerant from being sucked into the refrigerant compressor 17. The flow path switching means switches the flow direction of the refrigerant during the cooling operation, the heating operation, and the dehumidifying operation (dehumidifying cooling and dehumidifying heating). The four-way valve 23, the solenoid valves 24, 25, 26, and the check valve. It consists of valves 27, 28.

The flow path switching means switches the flow of the refrigerant as follows according to the cooling operation, the heating operation, and the dehumidifying operation. During the cooling operation, the refrigerant discharged from the refrigerant compressor 17 flows in the order of the four-way valve 23, the check valve 27, the outdoor heat exchanger 18, the pressure reducing device 20, the indoor evaporator 13, the accumulator 21, and the refrigerant compressor 17. (The flow of the refrigerant during the cooling operation is indicated by an arrow C in the figure).
During the heating operation, the refrigerant discharged from the refrigerant compressor 17 is
Four-way valve 23-> indoor condenser 14-> valve body 19a of subcool control valve 19-> check valve 28-> outdoor heat exchanger 18-> solenoid valve 25-> accumulator 21-> refrigerant compressor 17 Switching to flow in this order (this heating operation The flow of the refrigerant at that time is indicated by an arrow H in the figure). During the dehumidifying and cooling operation, the refrigerant discharged from the refrigerant compressor 17 is a four-way valve 23 → indoor condenser 14 → solenoid valve 24 → check valve 28 → outdoor heat exchanger 18 → pressure reducing device 2
The flow is switched in the order of 0 → indoor evaporator 13 → accumulator 21 → refrigerant compressor 17 (the refrigerant flow during this dehumidifying and cooling operation is indicated by arrow D _C in the figure). During the dehumidifying and heating operation, the refrigerant discharged from the refrigerant compressor 17 is discharged by the four-way valve 23.
→ Indoor condenser 14 → Subcool control valve 19 valve body 19
a-> check valve 28-> outdoor heat exchanger 18-> solenoid valve 26-> indoor evaporator 13-> accumulator 21-> refrigerant compressor 17 (flow of refrigerant during dehumidifying and cooling operation is indicated by arrow D in the figure) Indicated by _H ).

Next, the operation of this embodiment will be described. Since the indoor condenser 14 of the present embodiment has some subcool at the portion of the subcool control valve 19 with which the temperature sensitive tube 19b comes into contact, a little from upstream to downstream of the portion with which the temperature sensitive tube 19b comes into contact (see FIG. 2). The hatched area) is the supercooled area. Here, the third core portion 14c with which the temperature-sensitive tube 19b contacts is arranged on the windward side of the first core portion 14a and the second core portion 14b, and the air flowing in the duct 2 directly hits the first core portion 14c. Compared with the core portion 14a and the second core portion 14b, the temperature difference between the refrigerant and the air can be made larger.
Therefore, it is possible to reduce the core area required on the upstream side of the portion where the temperature-sensing cylinder 19b comes into contact so as to have a slight subcool at the portion where the temperature-sensing cylinder 19b comes into contact. In other words, it is possible to take subcool with a small core area.
As a result, the overall area of the indoor condenser 14 does not unnecessarily reduce the area of the heat exchange section that forms the gas-liquid two-phase region other than the supercooling region, and prevents the decrease in cycle efficiency due to the increase in high pressure. In addition, the amount of the refrigerant is not increased due to the increase in the liquid area. Further, since the high-pressure fluctuation and the fluctuation of the refrigerant amount are small with respect to the fluctuation of the subcool at the portion where the temperature-sensitive cylinder 19b comes into contact, cycle hunting can be suppressed and the system performance can be stabilized.

Next, a second embodiment of the present invention will be shown. FIG. 3 is a schematic diagram of the indoor unit portion according to the present embodiment. The indoor condenser 14 of this embodiment includes core portions 14a to 1 of the heat exchange portion.
4c are connected so that the flow direction of the refrigerant flowing in each of the core portions 14a to 14c is the same (flows from bottom to top in FIG. 3). In addition, the subcool control valve 19
Outside the duct 2, the second core portion 14b and the third core portion 1
The temperature-sensing cylinder 19b is brought into contact with the pipe connecting to 4c, and control is performed so that the temperature-sensing cylinder 19b has a slight subcool at the contacting portion. Therefore, the entire area of the third core portion 14c downstream of the portion in contact with the temperature sensitive cylinder 19b is the supercooling region. In this embodiment, the area upstream of the portion in contact with the temperature sensitive tube 19b is the downstream area of the second core portion 14b. Therefore, in order to have a slight amount of subcool at the portion where the temperature-sensitive cylinder 19b comes into contact, the subcool is provided in the downstream region of the second core portion 14b. The downstream region of the second core portion 14b is the third
Since it is arranged on the leeward side of the downstream region of the core portion 14c, the air that has passed through the downstream region of the third core portion 14c will hit. Here, when the temperature distribution of the air after the heat exchange with the refrigerant in the third core portion 14c is examined, as shown in FIG. 4, the lower temperature side of the refrigerant flowing through the third core portion 14c has a higher temperature. It will be lower than the basin side. As a result, the temperature difference between the refrigerant and the air can be made relatively large in the downstream region of the second core portion 14b, so that the core area required to have a subcool in the downstream region of the second core portion 14b increases. Can be prevented.

Next, a third embodiment of the present invention will be shown. FIG. 5 is a schematic diagram of the indoor unit portion according to the present embodiment. In the refrigeration cycle 4 of the present embodiment, the temperature sensing cylinder 19b of the subcool control valve 19 is brought into contact with the outlet pipe of the indoor condenser 14 to control the subcool at the outlet of the indoor condenser 14. In the core portions 14a to 14c of the indoor condenser 14, the refrigerant flow direction is the core portions 14a as in the case of the second embodiment.
They are connected so as to be the same at 14c. The subcool control valve 19 controls the subcool at the outlet of the indoor condenser 14 so as to have a subcool in the downstream region of the second core portion 14b in order to make the entire area of the third core portion 14c a supercooling region. Therefore, in the case of the present embodiment, as in the case of the second embodiment described above, the temperature difference between the refrigerant and the air can be made relatively large in the downstream region of the second core portion 14b, so that the second core portion 14b. It is possible to prevent the core area required to have a subcool in the downstream region of 14b from increasing.

[Brief description of drawings]

FIG. 1 is an overall schematic diagram of a vehicle air conditioner according to a first embodiment.

FIG. 2 is a schematic diagram of an indoor unit portion according to the first embodiment.

FIG. 3 is a schematic diagram of an indoor unit section according to a second embodiment.

FIG. 4 is a diagram showing a temperature distribution of air after passing through a third core portion (second embodiment).

FIG. 5 is a schematic diagram of an indoor unit portion according to a third embodiment.

FIG. 6 is a schematic view of an indoor unit section according to a conventional technique.

[Explanation of symbols]

 4 Refrigeration cycle 13 Indoor evaporator (refrigerant condenser) 14a 1st core part (1st heat exchange part) 14b 2nd core part (1st heat exchange part) 14c 3rd core part (2nd heat exchange part) 19 Subcool Control valve (supercooling degree adjustment valve)

Front Page Continuation (72) Inventor Hiroshi Ishikawa 1-1, Showa-cho, Kariya, Aichi Prefecture, Nihon Denso Co., Ltd. (72) Inventor Keita Honda 1-1-1-1, Showa-cho, Kariya, Aichi Prefecture, Nidec Corporation Within

Claims (2)

[Claims] 1. A first heat exchange unit having a heat exchange unit for condensing and liquefying a refrigerant passing therethrough by heat exchange with a cooling medium, the heat exchange unit constituting an upstream side of the heat exchange unit in the flow direction of the refrigerant. Section and a second heat exchange section forming a downstream side, and the first section
A refrigerant condenser in which a heat exchange section is arranged on the downstream side of the second heat exchange section in the flow direction of the cooling medium, and the refrigerant condenser downstream so as to become a supercooled region from the middle of the second heat exchange section. And a subcooling degree adjusting valve for adjusting the opening degree of the refrigerant flow path. 2. A first heat exchange unit having a heat exchange unit for condensing and liquefying a refrigerant passing therethrough by heat exchange with a cooling medium, the heat exchange unit constituting an upstream side of the heat exchange unit in the flow direction of the refrigerant. Section and a second heat exchange section forming a downstream side, and the first section
A refrigerant condenser in which a heat exchange section is arranged on the downstream side of the second heat exchange section in the flow direction of the cooling medium, and the refrigerant condenser downstream so that the entire area of the second heat exchange section is a supercooling zone. A refrigeration cycle including a subcooling degree adjusting valve for adjusting the opening degree of the refrigerant flow path of the first heat exchange section in the refrigerant flow direction, wherein the second heat exchange section is provided. The refrigeration cycle is arranged so as to be located on the downstream side in the flow direction of the cooling medium in the downstream region of the section.