JPH10119553A - Air conditioner for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pump type air conditioner for an automobile allowing quick heating by forcibly increasing the superheat of the refrigerant fed back to a compressor when the heating operation is started. SOLUTION: This air conditioner for an automobile selectably has the first cycle in which the refrigerant discharged from a compressor 6 flows in a heat exchanger 5 outside a car room and the second cycle in which the refrigerant discharged from the compressor 6 flows in a by-pass pipe 10. An electric heater 25 forcibly heating the refrigerant flowing in a low-pressure pipe 11a connecting the outlet of an evaporator 3 and the inlet of the compressor 6 is fitted to the low-pressure pipe 11a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for a vehicle, and more particularly to an air conditioner for a vehicle capable of performing rapid heating including at least a heat pump type heating cycle.

[0002]

2. Description of the Related Art In a conventional heating operation by an air conditioner for a vehicle, engine cooling water is used as a heat source, and a part of the engine cooling water is led to a heater core in a vehicle compartment, where heat exchange is performed with the vehicle interior air. Generally, a hot water type is used in which heated air is blown into a vehicle interior.

There is also known a heat pump type air conditioner which draws heat from outside air without using engine cooling water as a heat source for heating and uses the heat for heating a vehicle interior.

Further, in a so-called dual air conditioner in which air conditioning units are separately arranged for a front seat and a rear seat in a vehicle compartment, both are of a type using hot water, both are of a heat pump type, or one is of a type using hot water. And the other is a heat pump type.

[0005]

However, in the air conditioner utilizing hot water, the outside air temperature is low and the temperature in the vehicle compartment is low, as in the case where parking is performed at night in winter and driving is started in the early morning of the next morning. If the temperature is too low, the heating capacity at the start of the engine is extremely low, and it is difficult to obtain hot air at a desired temperature until the temperature of the engine coolant rises considerably. Further, since the hot water pipe for guiding the engine cooling water to the heater core and the refrigerant pipe for the evaporator for cooling are mixed in one unit, it is not preferable in terms of space and work.

On the other hand, in the heat pump type air conditioner, although the work of piping and the space are improved, the heat source for heating is mainly the energy given during the compression work of the compressor. Since the heating performance is given by the product of the amount of circulating refrigerant and the difference in enthalpy accompanying the compression work of the compressor, high heating performance cannot be obtained when the outside air temperature is low and the flow rate of the refrigerant is small. .

The present invention has been made to solve such a conventional problem. Particularly, at the time of starting a heating operation, the superheat of the refrigerant returning to the compressor is forcibly increased to enable rapid heating. It is an object of the present invention to provide a heat pump type air conditioner for automobiles.

[0008]

According to a first aspect of the present invention, there is provided a compressor, a heat exchanger outside a vehicle,
A heat exchanger, an expansion valve, and an evaporator, which are connected in this order by a refrigerant pipe, and a refrigerant pipe discharged from the compressor bypasses the external heat exchanger and short-circuits to the internal heat exchanger. A refrigerant flow switching valve provided in a refrigerant pipe downstream of the compressor to switch the flow path of the refrigerant discharged from the compressor to the outside heat exchanger side and the bypass pipe side,
The refrigerant flow switching valve switches between a first cycle in which refrigerant discharged from the compressor flows through the exterior heat exchanger and a second cycle in which refrigerant discharged from the compressor flows through the bypass pipe. An air conditioner for a vehicle, comprising: an electric heater attached to a low-pressure pipe connecting an outlet of the evaporator and an inlet of the compressor, and heating a refrigerant flowing in the low-pressure pipe. It is.

In this air conditioner for an automobile, even when the outside air temperature is low and the amount of circulating refrigerant is small, such as when heating operation is started in winter, the electric heater is operated. Since the second cycle is operated, the superheat of the refrigerant returning to the compressor is large, and the second cycle operates in a state where the pressure value of the refrigerant discharged from the compressor and the temperature value of the refrigerant are high. Therefore, compared with the state of the normal operation in which the electric heater is not operated, the refrigerant having a higher temperature and a higher pressure can be guided to the vehicle interior heat exchanger. As a result, the heating capacity of the vehicle interior heat exchanger is improved, and the temperature in the vehicle interior rapidly rises immediately after the start of operation, and rapid heating can be performed.

Further, the so-called forming, which is caused by the refrigerant in the lubricating oil, which occurs when the outside air temperature is low, can be prevented, sufficient lubrication can be achieved, and a large load is not applied to the sliding portion of the compressor. Insufficient lubrication oil of the compressor can be prevented. As a result, high-speed rotation of the compressor becomes possible, which can also improve the immediate warming performance by increasing the flow rate of the refrigerant.

According to a second aspect of the present invention, a three-way connector is provided between the exterior heat exchanger and the interior heat exchanger and between the evaporator and the compressor. A second expansion valve and a second evaporator are provided therebetween, and the second evaporator is provided in another air conditioning unit.

The invention according to claim 2 constitutes a so-called dual air conditioner having a plurality of air conditioning units, and the invention according to claim 1 is also applied to an air conditioning unit provided with a second evaporator. Regardless of whether or not to do so, at least the air-conditioning unit according to claim 1 achieves rapid heating, downsizing, and improvement in workability, so that the dual air conditioner has the same operation and effect.

According to the second aspect of the present invention, the second vehicle interior heat exchanger provided in the second air conditioning unit may be of a hot water type or a heat pump type.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a cycle configuration diagram of an air conditioner for a vehicle according to Embodiment 1 of the present invention. FIG. 1A shows a state during a rapid heating operation. (B) is a diagram for explaining a normal operation.

The air conditioner for a vehicle according to the present embodiment is a heat pump type air conditioner, and is shown in FIG.
As shown in (B), the air conditioning unit U has a duct 2 for sending air taken in from an intake unit (not shown) toward the vehicle interior, and as a heat exchanger, the duct 2 is inserted into the duct 2 from the upstream side. An evaporator 3 and a vehicle interior heat exchanger 4 (sub-condenser) mainly working during heating operation are arranged in order, and an outside vehicle heat exchanger 5 (main condenser) mainly working during cooling operation outside the duct 2. Are arranged.

An air mixing door 1 is provided upstream of the vehicle interior heat exchanger 4, and supplies the desired conditioned air by adjusting the ratio of the amount of air passing through the vehicle interior heat exchanger 4. Although not shown, a differential air outlet for blowing conditioned air to the inner surface of the windshield, a vent outlet for blowing conditioned air to the upper body of the occupant, and warm air at the feet of the occupant are provided on the downstream side of the vehicle interior heat exchanger 4. Various outlets such as a foot outlet for blowing out are provided.

The air conditioner for a vehicle is operated for cooling and heating using a refrigerant. In this device, a compressor 6, an exterior heat exchanger 5, a liquid tank 7, an interior heat exchanger 4, an expansion valve 8, and an evaporator 3 are connected by a refrigerant pipe 11, and a refrigerant is sealed therein. Further, in order to switch the heat exchangers 4 and 5 which function during the heating operation and the cooling operation, a three-way connector 9 for branching the flow of the refrigerant is provided at an inlet of the exterior heat exchanger 5, The three-way connector 9 is connected to a bypass pipe 10 that bypasses the exterior heat exchanger 5. The bypass pipe 10 connects the outlet of the exterior heat exchanger 5 and the entrance of the interior heat exchanger 4. The refrigerant pipe 11 is connected by a three-way connector 15. An electromagnetic valve 13 provided between the three-way connector 9 and the heat exchanger 5 outside the vehicle compartment
And the solenoid valve 14 provided in the bypass pipe 10 is controlled to open and close, thereby selecting the flow path of the refrigerant discharged from the compressor 6.

That is, the solenoid valve 13 is opened and the solenoid valve 14 is opened.
Is closed, the refrigerant discharged from the compressor 6 is guided to the exterior heat exchanger 5, which constitutes a first cycle in the case of performing cooling or temperature control operation.

On the other hand, when the solenoid valve 13 is closed and the solenoid valve 14 is opened, the refrigerant discharged from the compressor 6 is guided to the bypass pipe 10, and the second cycle in the case of performing the heating operation is performed. Configure.

In addition, a condenser fan device 12 as a blowing means for sending air to the heat exchanger 5 is provided on the back of the outside heat exchanger 5, and is provided on the downstream side of the outside heat exchanger 5. A check valve 16 is provided in the refrigerant pipe 11.
“PS” is a pressure switch for detecting the refrigerant pressure in the cycle.

The expansion valve 8 adjusts the amount of circulating refrigerant in accordance with the heat load on the evaporator 3 in order to prevent liquid compression in the compressor 6, so that the refrigerant is superheated at the outlet of the evaporator 3. I have. This degree of superheat (superheat amount) is usually about + 2 ° C. with respect to the saturation temperature of the refrigerant.

Here, when the vehicle engine is started and the compressor 6 is operated in a heating operation in a state where the outside air temperature is low, the heat load on the evaporator 3 is small. In order to obtain a degree, the expansion valve 8 is in a state where the valve opening degree is reduced. Therefore, the amount of the refrigerant circulated during the cycle by the expansion valve 8 becomes extremely small, and the amount of the refrigerant that is inevitably returned to the compressor 6 is also small, so that it becomes impossible to discharge a large amount of the refrigerant for heating.

Therefore, in the first embodiment, the refrigerant flowing through the low-pressure pipe 11a is heated on the way of the low-pressure pipe 11a connecting the outlet of the evaporator 3 and the inlet of the compressor 6, and is returned to the compressor 6. An electric heater 25 for forcibly increasing the superheat is mounted. This electric heater 25 is connected to a vehicle-mounted battery 27 via a switch 26. If the refrigerant is electrically heated by using the electric heater 25, the heating can be controlled by ON / OFF control of the switch 26, so that the control is easy. The workability of assembling to the pipe 11a is also improved.

Next, the operation of the first embodiment will be described.

In order to require rapid heating, for example, in the early morning of winter, as shown in FIG. 1A, the refrigerant discharged from the compressor 6 is directly passed through the bypass pipe 10 to the heat exchanger 4 in the vehicle interior. , Compressor 6 → liquid tank 7
A second cycle is formed for circulating the heat to the vehicle interior heat exchanger 4 → the expansion valve 8 → the evaporator 3 → the compressor 6. Further, the switch 26 is turned on to operate the electric heater 25 to forcibly heat the refrigerant flowing in the low-pressure pipe 11a.

In the second cycle, the gaseous refrigerant discharged from the compressor 6 and bypassed by the bypass pipe 10 through the exterior heat exchanger 5 is condensed and liquefied by the interior heat exchanger 4 to radiate heat. The cooled air is heated and blown into the cabin, thereby heating the cabin. At that time, the evaporator 3 cools the air and performs dehumidification.
Dehumidification heating will be realized. At this time, the temperature of the air blown into the vehicle interior is adjusted by adjusting the opening of the air mix door 1 disposed upstream of the vehicle interior heat exchanger 4.

In particular, in the first embodiment, since the second cycle is operated while the electric heater 25 is operated, the superheat of the refrigerant returning to the compressor 6 is large. The operation is performed in a state where the pressure Pd of the discharged refrigerant to be discharged and the temperature Td of the refrigerant are high. Therefore, the compressor 6 shown in FIG.
The refrigerant having a high temperature and a high pressure is discharged from the compressor 6 as compared with the pressure Pd of the refrigerant discharged from the compressor and the temperature Td of the refrigerant is low, and the heating capacity of the vehicle interior heat exchanger 4 is improved. The temperature in the room rises rapidly immediately after the start of operation, enabling rapid heating.

In addition, the so-called forming caused by the refrigerant in the lubricating oil, which occurs when the outside air temperature is low, can be prevented, sufficient lubrication can be achieved, and a large load is not applied to the sliding portion of the compressor 6. Insufficient lubrication oil of the compressor 6 at the time can also be prevented. As a result, the compressor 6 can be rotated at a high speed, so that it is possible to improve the immediate warming property by increasing the flow rate of the refrigerant.

On the other hand, by such a rapid heating operation,
When the temperature in the cabin rises to some extent, the operation is switched to normal operation. That is, the pressure switch PS shown in FIG.
The discharge pressure of the compressor 6 (the temperature of the discharged refrigerant in the case of a temperature switch) is detected by a (temperature switch), and when the discharge pressure (discharge temperature) reaches a predetermined pressure (temperature), the switch 26 is turned off. Thus, the heating of the refrigerant flowing through the low-pressure pipe 11a is stopped, and the heating operation is continued. In this heating operation, the air cooled and dehumidified by the evaporator 3 is heated by the indoor heat exchanger 4 to reach a desired temperature and is blown out into the vehicle interior. The operation of switching from the rapid heating operation to the normal operation may be performed by timer control.

Embodiment 2 FIG. 2 is a cycle configuration diagram of a vehicle air conditioner according to Embodiment 2 of the present invention.

The second embodiment is a dual type air conditioner for a vehicle in which two independent air conditioners are provided in parallel. As shown in FIG.
A front seat unit Ua for air-conditioning the outside air selectively taken in from an intake unit (not shown) and blowing it out to a front seat, and a rear seat unit Ub for air-conditioning the blown inside air and blowing it out to a rear seat. And

In the front seat unit Ua, an intake unit (not shown), an intake door, a blower, an evaporator 3a, an air mix door 1a, and a heater core 4a (not shown) are arranged in this order from the upstream side in the air passage. Is provided, and the first hot water line and the first refrigerant line are connected.

On the other hand, in the rear seat unit Ub, a blower, an evaporator 3b, an air mixing door 1b, and a vehicle interior heat exchanger 4b (not shown) are arranged in this order from the upstream side in the air passage. Are linked.

The first hot water line is configured by sequentially connecting the engine E, the water valve Wv, and the heater core 4a by piping.

The first refrigerant line includes a compressor 6, a three-way connector 9, a solenoid valve 13 for switching the flow direction of the refrigerant, a vehicle exterior heat exchanger 5, a check valve 16, a three-way connector 15, a liquid tank 7, a three-way connector 17, The electromagnetic valve 18, the expansion valve 8 a, the evaporator 3 a, and the three-way connector 19 are sequentially connected by a pipe 11.

The piping 1 between the three-way connectors 9 and 15
Reference numeral 0 denotes a bypass pipe for the heat exchanger 5 outside the vehicle compartment, which constitutes bypass means together with the electromagnetic valve 14.

The second refrigerant line includes a three-way connector 17, an electromagnetic valve 20 for switching the flow direction of the refrigerant, and a heat exchanger 4 for the vehicle interior.
b, the expansion valve 8b, the evaporator 3b, and the three-way connector 19 are sequentially connected by the pipe 11. In other words, the three-way connectors 17 and 19 enable the front seat unit Ua
From the first refrigerant line. Note that reference numeral “12” in the figure denotes a fan that promotes heat exchange between the outside air and the refrigerant in the external heat exchanger 5, and “PS” denotes a pressure switch for detecting the refrigerant pressure in the cycle.

On the way of the low-pressure pipe 11a connecting the outlet of the evaporator 3b and the inlet of the compressor 6, the refrigerant flowing in the low-pressure pipe 11a is heated to forcibly superheat the refrigerant returning to the compressor 6. An electric heater 25 for increasing the size is attached.

Next, the operation when the heating operation of the second embodiment is performed will be described.

In the heating operation according to the second embodiment, the front seat unit Ua and the rear seat unit Ub have different heat sources. The front seat unit Ua uses engine cooling water, and the rear seat unit Ub uses refrigerant. I have.

Therefore, when performing the heating operation, the electromagnetic valves 13 and 18 for switching the flow direction of the refrigerant are set to the “closed state”, the electromagnetic valves 14 and 20 are set to the “open state”, and the refrigerant from the compressor 6 is supplied in three directions. Connector 9 → Bypass tube 10 →
3-way connector 15 → liquid tank 7 → 3-way connector 1
7 → solenoid valve 20 → pressure switch PS → interior heat exchanger 4
b → expansion valve 8b → evaporator 3b → three-way connector 19
And let it flow. Further, the water valve Wv is also kept in the “open state”. Furthermore, like in the early morning of winter,
When rapid heating is required in a state where the outside air temperature is low and the temperature in the vehicle compartment is low, similarly to the above, the switch 26 is turned on to activate the electric heater 25 and flow through the low-pressure pipe 11a. The refrigerant is heated forcibly.

When the heating operation is performed in the state set as described above, the refrigerant discharged from the compressor 6 is discharged from the three-way connector 9 → the bypass pipe 10 → the three-way connector 15 → the liquid tank 7 → the three-way connector 17 → the solenoid valve 20 → the pressure. A second cycle is established in which the switch PS → the vehicle interior heat exchanger 4b → the expansion valve 8b → the evaporator 3b → the three-way connector 19 flows. In addition, the refrigerant that has entered the liquid tank L also flows while extruding the refrigerant stored in the liquid tank L.

In the second embodiment as well, the second cycle is operated in a state where the electric heater 25 is operated, similarly to the above, so that the superheat of the refrigerant returning to the compressor 6 is large, and the second cycle is performed. Is operated in a state where the pressure Pd of the refrigerant discharged from the compressor 6 and the temperature Td of the refrigerant are high. Therefore, the high-temperature and high-pressure refrigerant is discharged from the compressor 6 as compared with the normal operation state in which the switch 26 is turned off, and the vehicle interior heat exchanger 4b exchanges heat between the vehicle interior air and the high-temperature and high-pressure refrigerant,
The heated cabin air is sent into the cabin by the blower, thereby rapidly heating the cabin.

That is, since the vehicle interior is heated using the high-temperature and high-pressure refrigerant pressurized by the compressor 6, the temperature of the vehicle interior air rises extremely quickly and the immediate warming property is improved.

When the temperature in the passenger compartment rises to some extent by such a rapid heating operation, the operation is switched to the normal operation.
That is, the pressure switch PS (may be a temperature switch)
, The discharge pressure of the compressor (the temperature of the discharged refrigerant in the case of a temperature switch) is detected, and when the discharge pressure (discharge temperature) reaches a predetermined pressure (temperature), the switch 26 is turned off and flows through the low-pressure pipe 11a. The heating of the refrigerant is stopped, and the heating operation is continued. In this heating operation, the air cooled and dehumidified by the evaporator 3 is heated by the indoor heat exchanger 4b to reach a desired temperature and is blown into the vehicle interior.
The operation of switching from the rapid heating operation to the normal operation is as follows.
It may be performed by timer control.

In the second embodiment, the heating for the front seat is performed after the temperature of the engine cooling water rises. However, as described above, the heating is started in the rear seat unit Ub. Therefore, even while the temperature of the engine cooling water rises for a while, the occupants of the front seats are also in the rear seat unit U.
b.
Can survive the cold.

When the temperature of the engine coolant rises, the engine coolant having a large amount of heat is guided to the heater core 4a, and air at a desired temperature is also blown out to the front seat. Moreover, since the operation of the cooling cycle itself applies a load to the engine, the temperature rise of the engine cooling water also becomes faster than before.

In the second embodiment described above, only the rear-seat unit Ub performs a heating operation with good immediate warming. However, the present invention is not limited to this. It is also possible to provide a vehicle interior heat exchanger in the front seat unit Ua. In this case, the electric heater 25 is provided at a location after the two refrigerant lines have joined.

[0050]

As described above, according to the first aspect of the present invention, since the superheat of the refrigerant returning to the compressor is increased, the refrigerant heated to a high temperature and a high pressure by the compressor is guided to the vehicle interior heat exchanger. As a result, the heating capacity of the vehicle interior heat exchanger is improved, and the temperature in the vehicle interior rapidly rises immediately after the start of operation, and rapid heating can be performed.

Also, so-called forming caused by the refrigerant in the lubricating oil, which occurs when the outside air temperature is low, can be prevented, sufficient lubrication can be achieved, and a large load is not applied to the sliding portion of the compressor. Insufficient lubricating oil of the compressor can be prevented, and high-speed rotation of the compressor can be achieved. This can also improve immediate warming due to an increase in refrigerant flow rate.

According to the second aspect of the present invention, a plurality of air conditioning units which are excellent in instantaneous warming, and which are small in size by omitting hot water piping and excellent in workability of piping management are provided. So-called dual air conditioner can be provided.

[Brief description of the drawings]

1 is a cycle configuration diagram of an automotive air conditioner according to Embodiment 1 of the present invention, wherein FIG. 1 (A) illustrates a rapid heating operation and FIG. 1 (B) illustrates a normal operation. FIG.

FIG. 2 is a cycle configuration diagram of a vehicle air conditioner according to Embodiment 2 of the present invention.

[Explanation of symbols]

 3, 3a, 3b evaporator 4, 4a, 4b ... interior heat exchanger 5 ... exterior heat exchanger 6 ... compressor 8, 8a, 8b ... expansion valve 10 ... bypass pipe 11 ... refrigerant pipe 13, 14 ... solenoid valve (Refrigerant flow path switching valve) 9, 15, 17, 19 ... three-way connector 25 ... electric heater 26 ... switch 27 ... battery U, Ua, Ub ... air conditioning unit

Claims (2)

[Claims] 1. A compressor (6), a heat exchanger outside a vehicle compartment
(5) The vehicle interior heat exchanger (4, 4b), the expansion valve (8, 8b) and the evaporator (3, 3b) are connected in this order by the refrigerant pipe (11), and are discharged from the compressor (6). The refrigerant flowing around the vehicle interior heat exchanger (4, 4b) bypasses the vehicle exterior heat exchanger (5).
A bypass pipe (10) that is short-circuited to the compressor (6), and a compressor (6) for switching the flow path of the refrigerant discharged from the compressor (6) to the outside heat exchanger (5) side and the bypass pipe (10) side. 6) a refrigerant flow switching valve (13, 14) provided in a refrigerant pipe downstream of the compressor, and the refrigerant discharged from the compressor (6) by the refrigerant flow switching valve (13, 14). In an air conditioner for an automobile, a first cycle flowing through a heat exchanger outside a vehicle compartment (5) is switched to a second cycle in which refrigerant discharged from the compressor (6) flows through the bypass pipe (10). An electric heater (25) attached to a low-pressure pipe (11a) connecting an outlet of the evaporator (3, 3b) and an inlet of the compressor (6), and heating a refrigerant flowing in the low-pressure pipe (11a). An air conditioner for an automobile characterized by the above-mentioned. 2. A three-way connector (17, 19) between the exterior heat exchanger (5) and the interior heat exchanger (4b) and between the evaporator (3b) and the compressor (6). ), A second expansion valve (8a) and a second evaporator (3a) are provided between these three-way connectors (17, 19), and the second evaporator (3a) is connected to another air conditioning unit (Ua 2. The air conditioner for a vehicle according to claim 1, wherein