JP2000146319A - Heat pump type air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pump type air conditioner, increased in a refrigerant recovering rate upon switching the same into heating operation. SOLUTION: A heat pump type air conditioner is provided with a refrigerant pipeline 6, in which a compressor 1, an outdoor condenser 2, an indoor condenser 3, an expansion valve 4 and an indoor evaporator 5 are connected in this order, a bypass pipe 7, guiding refrigerant discharged out of the compressor into the indoor condenser while detouring the outdoor condenser, solenoid valves 8, 9, guiding the refrigerant discharged out of the compressor 1 to the side of the outdoor condenser 2 upon cooling operation while guiding the refrigerant to the bypass pipe 7 upon heating operation, and a refrigerant recovering pipe 10 for returning the refrigerant, stagnated in the outdoor condenser 2, to the suction side of the compressor 1. An opening and closing valve 11 is provided between one end of the refrigerant recovering pipe at the suction side of the compressor 1 and the outlet port side of the indoor evaporator 5 while the opening and closing valve 11 is closed for a predetermined period of time upon starting the heating operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump type air conditioner which performs cooling and heating by using a refrigerant, and more particularly to a heat pump type air conditioner which has a high refrigerant recovery rate when switching to a heating operation.

[0002]

2. Description of the Related Art In a heat pump type air conditioner, an indoor heat exchanger (indoor condenser) 3 called a sub-condenser is provided in an air conditioning unit 13 as shown in FIG. This system is used as a heating heat source. In other words, both the cooling and the heating perform the heat cycle operation using the refrigerant to cool and heat the room.

Outside the air conditioning unit 13, an outdoor heat exchanger (outdoor condenser) 2 called a main condenser is provided, and condensers 2, 3 functioning during heating operation and cooling operation by two solenoid valves 8, 9 are provided. By switching, the operation mode is switched. That is, during the cooling operation, the refrigerant discharged from the compressor 1 is introduced into the main condenser 2, and during the heating operation, the bypass pipe 7
, Bypasses the main capacitor 2 and is directly introduced into the sub capacitor 3. For convenience, in the following description, the refrigeration cycle formed during the cooling operation is referred to as a cooling cycle, and the refrigeration cycle formed during the heating operation is referred to as a heating cycle.

[0004] In such a heat pump type air conditioner, a heating cycle is formed to bypass the main condenser 2 during the heating operation, so that if the refrigerant stays in the main condenser 2 excessively, the amount of the refrigerant circulating in the heating cycle may become insufficient. There is.

Accordingly, the applicant of the present application has proposed a method of returning the so-called stagnant refrigerant, which is retained in the main condenser 2, to the suction side of the compressor 1 between the main condenser 2 and the suction side of the compressor 1 when starting the heating operation. It has been previously proposed to provide a refrigerant recovery pipe 10 and an electromagnetic valve 12 in the apparatus.

Incidentally, some heat pump type air conditioners use a heater core system which uses engine cooling water as a heat source in addition to a heat pump system which uses a refrigerant as a heat source in order to improve heating performance. In general, a dehumidifying heating is realized by incorporating a dehumidifying function, and fogging of a windshield is prevented to ensure safe driving. Furthermore, it is also useful as an air conditioner for electric vehicles and railway vehicles that cannot use engine cooling water in the first place.

[0007]

In the above-described conventional heat pump type air conditioner, when the heating operation is started, the solenoid valve 12 is opened so that the refrigerant stored in the main condenser 2 is compressed via the refrigerant recovery pipe 10. However, when the indoor temperature becomes higher than the outdoor temperature as in the case of intense solar radiation in winter, the amount of heat exchange in the sub-condenser 3 decreases, and the refrigerant pressure on the suction side of the compressor 1 is sufficiently increased. Does not drop. For this reason, even if the refrigerant recovery pipe 10 is provided, the recovery rate of the stagnant refrigerant of the main condenser 2 has a certain limit.

[0008] The present invention has been made in view of such problems of the prior art, and it is an object of the present invention to provide a heat pump type air conditioner having an improved refrigerant recovery rate when switching to a heating operation. .

[0009]

In order to achieve the above object, a heat pump type air conditioner of the present invention comprises at least a compressor (1), an outdoor condenser (2), an indoor condenser (3), and a pressure reducing means (4). And the indoor evaporator (5) are connected in this order by a refrigerant pipe (6),
A bypass pipe (7) for guiding the refrigerant discharged from the compressor to the indoor condenser by bypassing the outdoor condenser, and guiding the refrigerant discharged from the compressor to the outdoor condenser side during the cooling operation; A heat pump type air conditioner comprising: refrigerant flow switching means (8, 9) for leading to the bypass pipe; and a refrigerant recovery pipe (10) for returning refrigerant staying in the outdoor condenser to the suction side of the compressor. The apparatus is characterized in that an on-off valve (11) is provided between one end of the refrigerant recovery pipe on the suction side of the compressor and an outlet side of the indoor evaporator.

At this time, the opening and closing valve is characterized in that it is closed for a predetermined time when the heating operation is started.

In the heat pump type air conditioner of the present invention, an on-off valve is provided between one end of the refrigerant recovery pipe on the suction side of the compressor and the outlet side of the indoor evaporator. If you close for a time,
Regardless of the indoor temperature condition, the refrigerant flowing from the indoor condenser and the indoor evaporator to the suction side of the compressor is shut off.

Therefore, the refrigerant pressure on the suction side of the compressor decreases with the driving of the compressor,
The refrigerant stored in the outdoor condenser is sucked into the compressor through the refrigerant recovery pipe.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are block diagrams showing an embodiment of a heat pump type air conditioner of the present invention. FIG. 1 shows a steady operation and FIG. 2 shows a heating operation start.

This air conditioner has an air conditioning unit 13 that selectively takes in air inside and outside the room (inside and outside air), air-conditions the air, and blows the air toward a predetermined place in the room.

The air conditioning unit 13 has a duct 14 for sending the introduced air toward the room. Inside the duct 14, an inside air intake port and an inside air intake port are arranged in order from the upstream side in the air flow direction indicated by a white arrow. An intake door for selectively opening and closing the outside air intake, a blower fan for introducing the inside and outside air selected by the intake door into the duct 14 and forcing the air toward the downstream side (both not shown), It has an indoor evaporator 5 (hereinafter also simply referred to as “evaporator”) for evaporating and cooling the air, and a sub-condenser 3 as an indoor condenser for mainly operating during a heating operation and condensing and liquefying a gas refrigerant to heat the air. are doing.

Although not shown, an air mix door for adjusting the ratio of the air passing through the sub-condenser 3 and the air bypassing the sub-condenser 3 is rotatably provided on the front surface of the sub-condenser 3. On the downstream side of the sub-condenser 3, various air outlets for blowing the temperature-controlled air toward a predetermined place in the room are formed.

This heat pump type air conditioner performs indoor cooling and dehumidifying and heating by performing a heat cycle operation using a refrigerant for both cooling and heating.
It has the same refrigeration cycle as before.

That is, outside the air conditioning unit 13,
Compressor 1 rotationally driven by an unillustrated engine
And a main condenser 2 serving as an outdoor condenser mainly working during the cooling operation. The refrigeration cycle
A compressor 1, a main condenser 2, a sub condenser 3, a liquid tank 15, an expansion valve 4 as a pressure reducing means,
The evaporator 5, the sub-evaporator 19 and the accumulator 16 are connected in this order by the refrigerant pipe 6, and the refrigerant is sealed therein.

The liquid tank 15 separates gas and liquid, stores the liquid refrigerant once, and sends out only the liquid refrigerant to the expansion valve 4. The liquid tank 15 usually has a function of separating air and removing moisture and foreign matter. I have.

The expansion valve 4 decompresses and expands the liquid refrigerant into a low-temperature and low-pressure mist-like refrigerant that is easy to evaporate and senses the outlet temperature of the evaporator 5 to automatically adjust the refrigerant flow rate (in the case of a temperature-operated type). Has functions.

The accumulator 16 is for storing the surplus refrigerant and separating gas and liquid and returning only the gas refrigerant to the compressor 1. Since the accumulator 16 is a container having a relatively large capacity, it is assumed that the refrigerant is in a liquid state. , It can be vaporized and returned to the compressor 1, and damage to the compressor 1 due to liquid compression can be prevented.

Here, since the liquid tank 15 and the accumulator 16 generally have some common functions, it is not always necessary to always provide both of them. However, in the present invention, as will be described later, the outlet of the main condenser 2 is used. At least the accumulator 16 is preferably not omitted in order to recover the refrigerant as the liquid refrigerant. Therefore, for example, when the temperature-operated expansion valve 4 is used as the pressure reducing means as in the present embodiment, the liquid tank 15 and the accumulator 1
In the case where a so-called solenoid valve with an orifice (a flow switching solenoid valve whose valve position can be switched between two stages of a fully open state and a throttle state) is used instead of the temperature-operated expansion valve 4 as the pressure reducing means. Alternatively, only the accumulator 16 may be provided, and the liquid tank 15 may be omitted.

Incidentally, the sub-evaporator 19 provided between the evaporator 5 and the accumulator 16 is a type of heat exchanger connected to the sheathed heater 20 for heating the refrigerant, such as in winter. When the outside air temperature is low, the refrigerant temperature also decreases, and is a preheating means for supplying the gaseous refrigerant to the compressor 1 when the compressor 1 is started. However, the heat pump type air conditioner of the present invention is not always essential, and may be omitted.

Reference numeral 17 in the drawing denotes a check valve for preventing flow in the opposite direction, and reference numeral 18 denotes a condenser fan for sending air to the main condenser 2 and cooling it.

In this embodiment, in order to switch the condenser functioning between the heating operation and the cooling operation, the refrigerant flow switching means is provided between the discharge □ of the compressor 1 and the inlet of the main condenser 2 and in the bypass pipe 7. Solenoid valve 8,
9 are provided. By selectively switching the solenoid valves 8 and 9, a cooling cycle for guiding the refrigerant discharged from the compressor 1 to the main condenser 2 and a refrigerant discharged from the compressor 1 directly to the sub-condenser 3 via the bypass pipe 7. The induction heating cycle is switched.

That is, during the cooling operation, the solenoid valve 8 is opened and the solenoid valve 9 is closed, and the refrigerant discharged from the compressor 1 is discharged from the solenoid valve 8 → the main condenser 2 → the sub condenser 3 → the liquid tank 15 → the expansion valve 4 → the evaporator 5 A cooling cycle is formed in which the sub-evaporator 19 flows through the accumulator 16 and returns to the compressor 1. Thereby, in the evaporator 5, heat exchange between the mist refrigerant and the intake air is performed, the intake air passing around the refrigerant passage is evaporated while the mist refrigerant evaporates, and the room is cooled. Further, in the main condenser 2, the heat taken by the evaporator 5 is released to the outside by heat exchange with the outside air to cool the gas refrigerant and condense and liquefy it. At this time, the sub-condenser 3 hardly functions as a heat exchanger.

On the other hand, during the heating operation, the electromagnetic valve 8 is closed and the electromagnetic valve 9 is opened, and the refrigerant discharged from the compressor 1 is directly introduced into the sub-condenser 3 via the bypass pipe 7. That is, the refrigerant discharged from the compressor 1 to be used by the main condenser 72 is discharged from the solenoid valve 9 → the bypass pipe 7 → the sub condenser 3 → the liquid tank 15 → the expansion valve 4 → the evaporator 5 → the sub evaporator 19 → the accumulator 1
6 and form a heating cycle which returns to the compressor 1. Thereby, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 and bypassing the main condenser 2 is
The air condensed and liquefied by the sub-condenser 3 to radiate heat, and the air cooled by the evaporator 5 is heated and blown out into the room to heat the room. At that time, the evaporator 5 cools the intake air to perform dehumidification, so that dehumidification heating is realized.

Reference numeral 21 in the figure is a check valve for preventing the flow in the opposite direction, and prevents the refrigerant flowing out of the main condenser 2 from flowing back to the solenoid valve 9.

In the present embodiment, a refrigerant recovery system for returning the refrigerant stagnating in the main condenser 2 to the suction side of the compressor 1 at the time of starting the heating operation is to recover the refrigerant from the outlet of the main condenser 2. .
That is, by connecting the refrigerant recovery pipe 10 to the outlet pipe of the main condenser 2 via a three-way connector, a refrigerant recovery line is branched and formed, and the solenoid valve 12 and the reverse valve are connected to the refrigerant recovery pipe 10 (refrigerant recovery line). A stop valve 22 is provided, and the other end of the refrigerant recovery pipe 10 is connected to the inlet side of the accumulator 16 via a three-way connector to return the refrigerant. The solenoid valve 12 is provided to prevent the refrigerant flowing out of the main condenser 2 from flowing to the refrigerant recovery line 10 during the cooling operation.

As described above, if the refrigerant is recovered from the outlet of the main condenser 2, the main condenser 2
Inside, the liquid refrigerant is stored in the lower part, so that the refrigerant can be recovered in a liquid state. Therefore, the refrigerant recovery time and the yield of the refrigerant are greatly improved as compared with the case where the refrigerant is recovered in a gas state.

Particularly, in this embodiment, the sub-evaporator 1
An electromagnetic valve (corresponding to an on-off valve according to the present invention) 11 is provided between 9 and one end of the refrigerant recovery pipe 10, and this electromagnetic valve 11 is closed for a predetermined time when the heating operation is started. The opening and closing operation of the solenoid valve 11 is performed by the microcomputer 23
The opening and closing operations of the other solenoid valves 8, 9 and 11 are also performed by the command signal from the microcomputer 23.

Next, the operation will be described. When the cooling operation is performed, the compressor 1 is driven by closing the solenoid valves 9 and 12 and opening the solenoid valves 8 and 11 as shown in FIG. The sheath heater 19 does not operate.

Thus, the refrigerant discharged from the compressor 1 is supplied to the solenoid valve 8 → the main condenser 2 → the check valve 17.
→ Subcondenser 3 → Liquid tank 15 → Expansion valve 4 →
Evaporator 5 → Sub-evaporator 19 → Solenoid valve 11 →
It returns to the compressor 1 through the accumulator 16. This is a cooling cycle formed at the time of cooling. The intake air is cooled by the evaporator 5, and the cool air is supplied to the room.

On the other hand, when performing the heating operation,
As shown in FIG. 2, the solenoid valves 9 and 12 are opened, the solenoid valve 8 is closed, and the compressor 1 is driven. When the compressor 1 is started, the solenoid valve 11 is closed. Thereby, the compressor 1
As the pressure of the refrigerant on the suction side of the compressor 1 decreases with the drive of the compressor 1, most of the gaseous and liquid refrigerants that have fallen in the main condenser 2 have a refrigerant recovery pipe 1
0 and is sucked into the compressor 1. After performing this refrigerant collection for a predetermined time, when the solenoid valve 11 is opened, the refrigerant discharged from the compressor 1 is discharged from the solenoid valve 9 to the check valve 2.
1 → Subcondenser 3 → Liquid tank 15 → Expansion valve 4
→ evaporator 5 → sub-evaporator 19 → solenoid valve 11
→ Return to the compressor 1 through the accumulator 16. This is a heating cycle formed at the time of heating. After the intake air is cooled by the evaporator 5, the cold air is heated by the sub-condenser 3, so that the dehumidified and heated low-humidity and high-temperature air is supplied to the room. Will be.

The embodiments described above are described for the purpose of 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.

[0036]

As described above, according to the present invention, as the compressor is driven, the refrigerant pressure on the suction side of the compressor is reduced, and the refrigerant stored in the outdoor condenser is sucked into the compressor through the refrigerant recovery pipe. Therefore, the amount of refrigerant in the heating cycle during the heating operation can be sufficiently ensured, and the heating performance is enhanced.

[Brief description of the drawings]

FIG. 1 is a block diagram (at the time of steady operation) showing an embodiment of a heat pump type air conditioner of the present invention.

FIG. 2 is a block diagram (at the time of starting a heating operation) showing an embodiment of a heat pump type air conditioner of the present invention.

FIG. 3 is a block diagram showing a conventional heat pump type air conditioner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Compressor 2 ... Main condenser (outdoor condenser) 3 ... Sub-condenser (indoor condenser) 4 ... Expansion valve (decompression means) 5 ... Indoor evaporator 6 ... Refrigerant piping 7 ... Bypass pipe 8, 9 ... Solenoid valve (refrigerant flow path switching) Means) 10: Refrigerant recovery pipe 11: Solenoid valve (open / close valve)

Claims (2)

[Claims] At least a compressor, an outdoor condenser, an indoor condenser, a pressure reducing means and an indoor evaporator are connected in this order by a refrigerant pipe, and a bypass for guiding refrigerant discharged from the compressor to the indoor condenser by bypassing the outdoor condenser. A pipe, refrigerant flow switching means for guiding the refrigerant discharged from the compressor to the outdoor condenser side during the cooling operation, and guiding the refrigerant discharged to the bypass pipe during the heating operation, and supplying the refrigerant remaining in the outdoor condenser to the compressor. A heat pump type air conditioner including a refrigerant recovery pipe for returning to the suction side of the compressor, one end of the refrigerant recovery pipe on the suction side of the compressor,
An on-off valve is provided between the indoor evaporator and an outlet side of the indoor evaporator. 2. The heat pump type air conditioner according to claim 1, wherein the on-off valve is closed for a predetermined time when the heating operation is started.