JP2002326512A - Heat pump type air conditioner for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner for a heat pump type automobile capable of managing both protection of a compressor and comfortableness of the air conditioning at a high dimension. SOLUTION: When delivery pressure of the compressor increases, the opening and closing of a water valve for a sub evaporator is controlled in the stage before the ON/OFF control of the compressor.

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 vehicle air conditioner for cooling and heating the interior of a vehicle using engine cooling water and refrigerant.

[0002]

2. Description of the Related Art For example, in recent luxury cars and one-box cars having a relatively large cabin space, the front area of the cabin is controlled by a front unit so that a comfortable air-conditioning state can be obtained for the entire cabin. The rear area is equipped with a so-called dual air conditioner, which is independently air-conditioned by a rear unit.

In this air conditioner for a vehicle, for example, in a heating operation, there is a system in which a front unit uses engine cooling water as a heat source and a rear unit uses a high-temperature and high-pressure refrigerant as a heat source.

[0004] However, if the heating operation is performed when the outside air temperature is low and the temperature of the engine cooling water is low as in the winter morning, warm air is not blown out at the same time as the operation starts because the temperature of the refrigerant rises slowly. The so-called immediate heating property is insufficient, and the heating performance may be insufficient. In particular, this tendency is remarkable in a one-box car having a large vehicle interior space equipped with a diesel engine, since the temperature rise of engine cooling water is slower than that of a normal gasoline engine vehicle.

Therefore, at present, a heat pump type air conditioner for a vehicle has been developed in which a refrigerant is heated by utilizing heat of engine cooling water and a higher heating performance is exhibited by using a higher temperature refrigerant having an increased enthalpy. (See, for example, Japanese Patent Application No. 7-271621).

[0006]

When the discharge pressure of the compressor rises, the compressor is turned on / off according to the discharge pressure to protect the compressor.
Control for performing FF (ON / OFF control) is generally performed, and in the above-described heat pump type air conditioner for a vehicle, it is natural that measures should be taken to protect the compressor when the pressure rises. It is.

However, ON / OF of the compressor
With only the F control, a shock (impact), noise, or the like is generated in accordance with ON / OFF of the magnet clutch, and drivability may be reduced.

Further, when the compressor is turned off, the circulation of the refrigerant stops and the refrigeration cycle does not function. For example, during the heating operation, the compressor is turned off.
When F is reached, the cool air is immediately blown into the vehicle interior, which may impair the comfort of air conditioning. In particular, in a heat pump type air conditioner for a vehicle, since excellent heating performance is obtained,
On the contrary, the sense of discomfort when the cold wind blows is large, and it is desired that the temperature change of the blown wind be suppressed as small as possible without impairing the comfort of the occupant.

The present invention has been made in view of the above-mentioned problems in a heat pump type air conditioner for a vehicle currently being developed by the present applicant, and achieves higher levels of protection of a compressor and comfort of air conditioning. It is an object of the present invention to provide a heat pump type air conditioner for a vehicle that can be driven.

[0010]

According to a first aspect of the present invention, there is provided an evaporator constituting a refrigeration cycle together with a compressor and a condenser, and engine cooling water can be circulated at an outlet of the evaporator. In a heat pump type air conditioner for a vehicle, a sub-evaporator is connected, and the sub-evaporator utilizes the engine cooling water to heat a refrigerant flowing into the sub-evaporator and then returns the refrigerant to the compressor. A flow control valve for controlling a flow rate of the circulating engine cooling water is provided, and an opening degree of the flow control valve is controlled according to a heat load state of the vehicle during a heating operation.

According to the first aspect of the invention, when the opening of the flow control valve is controlled in accordance with the heat load state of the vehicle during the heating operation, the flow rate of the engine cooling water flowing to the sub-evaporator is controlled. In addition, since the amount of heat absorbed from the engine cooling water to the refrigerant is adjusted, it is possible to bring out a detailed heating performance according to the heat load state of the vehicle.

[0012] According to a second aspect of the present invention, the first unit and the second unit for sending the taken air toward the vehicle interior.
A heater core having a unit, in which the engine cooling water circulates in the ventilation path of the first unit in order from the downstream side;
A first evaporator that constitutes a refrigeration cycle together with a compressor and a first condenser respectively disposed outside the first and second units;
In the ventilation path of the unit, a second condenser and a second evaporator connected in parallel with the first evaporator and connected in series with each other are arranged in order from the downstream side, and the refrigerant discharged from the compressor is disposed in the ventilation path. A circuit switching valve for switching between a refrigerant circuit for cooling operation leading to the first condenser and a refrigerant circuit for heating operation leading the refrigerant to a bypass passage bypassing the first condenser, provided outside the first and second units; Arranging a sub-evaporator connected to an outlet of the second evaporator and circulating the engine cooling water, and heating the refrigerant flowing into the sub-evaporator by using the engine cooling water by the sub-evaporator; In a heat pump type air conditioner for a vehicle which is returned to a compressor, A flow control valve for controlling the flow rate of the engine cooling water circulating through the heater, during heating operation, the opening degree of the flow control valve is controlled in accordance with the heat load state of the vehicle. I do.

According to the second aspect of the invention, when the opening degree of the flow control valve is controlled in accordance with the heat load state of the vehicle during the heating operation, the flow rate of the engine cooling water flowing to the sub-evaporator is controlled. Since the amount of heat absorbed from the engine cooling water to the refrigerant is adjusted, even in an air conditioner for an automobile having two units, it is possible to bring out a detailed heating performance according to the heat load state of the vehicle.

According to a third aspect of the present invention, the flow control valve is set to a fully closed state when the discharge pressure of the compressor rises to a first set value smaller than a reference value at which the compressor should be stopped. Then, when the pressure falls below a second set value that is smaller than the first set value, it is set to a fully open state.

According to the third aspect of the invention, when the compressor discharge pressure rises to a first set value (<reference value) or more during the heating operation, the flow control valve is set to a fully closed state.
As a result, the engine cooling water does not flow to the sub-evaporator or the like, and the sub-evaporator or the like does not function. Therefore, the temperature of the refrigerant sucked into the compressor decreases, and the discharge pressure of the compressor decreases. Then, when the compressor discharge pressure falls below the second set value (<first set value), the flow control valve is set to the fully open state again. As a result, the sub-evaporator and the like begin to function again, and the compressor discharge pressure increases. When the first and second set values are appropriately selected, by repeating such control, the temperature change of the blown wind can be reduced (that is,
The compressor can be protected (without compromising comfort). In addition, at that time, the ON / OFF control of the flow control valve is performed before the compressor is stopped, so that the operation frequency of the ON / OFF control of the compressor is reduced.

According to a fourth aspect of the present invention, the first unit and the second unit for sending the air taken into the vehicle interior, respectively.
A heater core having a unit, in which the engine cooling water circulates in the ventilation path of the first unit in order from the downstream side;
A first evaporator that constitutes a refrigeration cycle together with a compressor and a first condenser respectively disposed outside the first and second units;
In the ventilation path of the unit, a second condenser and a second evaporator connected in parallel with the first evaporator and connected in series with each other are arranged in order from the downstream side, and the refrigerant discharged from the compressor is disposed in the ventilation path. A circuit switching valve for switching between a refrigerant circuit for cooling operation leading to the first condenser and a refrigerant circuit for heating operation leading the refrigerant to a bypass passage bypassing the first condenser, provided outside the first and second units; Arranging a sub-evaporator connected to an outlet of the second evaporator and circulating the engine cooling water, and heating the refrigerant flowing into the sub-evaporator by using the engine cooling water by the sub-evaporator; In a heat pump type air conditioner for automobiles that is returned to the compressor, during heating operation, Third discharge pressure of the serial compressor is smaller than the reference value to stopping said compressor
When the pressure rises above the set value, the on-off valve for controlling the introduction of the refrigerant into the first evaporator is opened, and when the discharge pressure of the compressor falls below the fourth set value smaller than the third set value, The on-off valve is returned to the closed state.

According to the fourth aspect of the present invention, when the compressor discharge pressure rises to a third set value (<reference value) or more during the heating operation, the on-off valve is opened to allow the refrigerant to flow also to the first evaporator. To As a result, the discharge pressure of the compressor is reduced, and the compressor is protected. Then, when the compressor discharge pressure falls below the fourth set value (<third set value), the on-off valve is closed again to prevent the refrigerant from flowing into the first evaporator. This returns to the normal heating operation refrigerant circuit. Moreover, since such opening / closing control of the on-off valve is performed before the compressor is stopped, the frequency of ON / OFF control of the compressor is reduced.

According to a fifth aspect of the present invention, the first unit and the second unit for sending the air taken into the vehicle interior, respectively.
A heater core having a unit, in which the engine cooling water circulates in the ventilation path of the first unit in order from the downstream side;
A first evaporator that constitutes a refrigeration cycle together with a compressor and a first condenser respectively disposed outside the first and second units;
In the ventilation path of the unit, a second condenser and a second evaporator connected in parallel with the first evaporator and connected in series with each other are arranged in order from the downstream side, and the refrigerant discharged from the compressor is disposed in the ventilation path. A circuit switching valve for switching between a refrigerant circuit for cooling operation leading to the first condenser and a refrigerant circuit for heating operation leading the refrigerant to a bypass passage bypassing the first condenser, provided outside the first and second units; Arranging a sub-evaporator connected to an outlet of the second evaporator and circulating the engine cooling water, and heating the refrigerant flowing into the sub-evaporator by using the engine cooling water by the sub-evaporator; In a heat pump type air conditioner for automobiles that is returned to the compressor, during heating operation, The discharge pressure of the serial compressor is smaller than the reference value to stopping the compressor 5
When the pressure exceeds the set value, the circuit switching valve is switched to the cooling operation side, and the discharge pressure of the compressor is reduced to the fifth pressure.
The circuit switching valve is returned to the heating operation side when it falls below a sixth set value smaller than the set value.

According to the fifth aspect of the present invention, when the discharge pressure of the compressor rises to the fifth set value (<reference value) or more during the heating operation, the circuit switching valve is switched to the cooling operation side. As a result, the refrigerant flows into the first condenser outside the unit, the discharge pressure of the compressor is reduced, and the compressor is protected. Then, when the compressor discharge pressure falls below the sixth set value (<fifth set value), the circuit switching valve is returned to the heating operation side. This returns to the normal heating operation refrigerant circuit. Moreover,
Such switching control of the circuit switching valve is performed before the compressor is stopped.
The operation frequency of the N / OFF control is reduced.

[0020]

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

FIG. 1 is a schematic configuration diagram showing an embodiment of a heat pump type air conditioner for a vehicle according to the present invention, FIG. 2 is a schematic configuration diagram showing a state of the device during a heating operation, and FIG. It is a schematic structure figure showing the state at the time of cooling operation.

This air conditioner for a vehicle includes a front unit 10 as a first unit and a first unit for blowing air toward the front seat and the rear seat in the vehicle interior by air-conditioning the inside and outside air selectively taken in by a blower (not shown). And a rear unit 20 as two units.

The front unit 10 has a ventilation passage 11 formed in a casing thereof. In the ventilation passage 11, the engine cooling heated by the engine 1 is arranged in order from the downstream side in the air flow direction indicated by the white arrow. A heater core 12 through which water (hot water) circulates, and a front evaporator 13 as a first evaporator constituting a refrigeration cycle described later
And are arranged. Although not shown, in more detail, the front unit 10 includes, in order from the upstream, an intake unit, a cooling unit, and a heater unit.The intake unit is provided with an intake door and the blower. The front evaporator 13 is arranged, and an air mix door and the heater core 12 are arranged in the heater unit. The air mixing door is provided on the front surface of the heater core 12 and adjusts the ratio of hot air passing through the heater core 12 to cold air bypassing the heater core 12 to produce air at a desired temperature downstream of the heater core 12, or To prevent air from circulating. Further, various outlets are formed downstream of the heater core 12 of the heater unit for blowing out the temperature-adjusted air after the air mixing toward the front seat in the vehicle compartment.

On the other hand, the rear unit 20 has a ventilation passage 21 formed in a casing thereof, and a refrigeration cycle is formed in the ventilation passage 21 in order from the downstream side in the air flow direction indicated by the white arrow. A sub-condenser 22 as a second condenser and a rear evaporator 23 as a second evaporator are provided. The sub-condenser 22 and the rear evaporator 23 are both connected to the front evaporator 13 in the circuit of the refrigeration cycle.
And are connected in series with each other. Although not shown, in more detail, the rear unit 20 also includes an intake unit, a cooling unit, and a heater unit in order from the upstream side, similarly to the front unit 10, and the intake unit and the blower are arranged in the intake unit. The cooling unit is provided with the rear evaporator 23, and the heater unit is provided with an air mixing door and the sub-condenser 22.
Is arranged. The air mix door is provided on the front surface of the sub-condenser 22 and adjusts the ratio of hot air that has passed through the sub-condenser 22 and cool air that has bypassed the sub-condenser 22 to create air at a desired temperature downstream of the sub-condenser 22, Alternatively, air is prevented from flowing through the sub-condenser 22. On the downstream side of the sub-condenser 22 of the heater unit, there are formed various outlets for blowing out the temperature-adjusted air after the air mixing toward the rear seat in the vehicle compartment.

Outside these two units 10 and 20,
A compressor 2 rotationally driven by an engine 1;
A main capacitor 3 functioning as a first capacitor is provided. The refrigeration cycle includes the compressor 2, the main condenser 3, the front evaporator 13,
The sub-condenser 22 and the rear evaporator 23 are connected by piping to the first liquid tank 14, the first expansion valve 15 for the front evaporator 13, the second liquid tank 24, and the second expansion valve 25 for the rear evaporator 23. It is configured.

On the inlet side of the main condenser 3, a four-way valve 4 as a circuit switching valve is provided. This four-way valve 4
Is provided with one inlet port and three outlet ports in a sealed case, a slide member communicating with two of the three outlet ports in the case, and an outlet port selected by the slide member. The other outlet ports are configured to communicate with the inlet port. Therefore, an outlet port communicating with the inlet port is selected depending on the position of the slide member. Here, the inlet port of the four-way valve 4 is the compressor 2
And the three output ports of the four-way valve 4
The inlet of the main condenser 3 and the compressor 2
And the outlet of the main condenser 3 (bypass passage 6). This four-way valve 4
Accordingly, a refrigerant circuit for cooling operation (hereinafter, simply referred to as a “cooling circuit”) for guiding the refrigerant discharged from the compressor 2 to the main condenser 3 and a heating for guiding the refrigerant discharged from the compressor 2 to the bypass passage 6 of the main condenser 3. An operation refrigerant circuit (hereinafter simply referred to as a “heating circuit”) is switched. Details of the cooling circuit and the heating circuit will be described later.

A sub-evaporator 30 functioning as a third evaporator is provided between the suction side of the compressor 2 and the outlet of the rear evaporator 23 in order to enhance the heating performance. Have been. The sub-evaporator 30 has a function of heating the refrigerant flowing inside by exchanging heat with engine cooling water (warm water). Its structure is, for example, as shown in FIG. Further, in this case, preferably, the heat sensitive portion 27 of the second expansion valve 25 is attached to the outlet of the sub-evaporator 30.

By providing such a sub-evaporator 30, even if the engine cooling water cannot be used for heating immediately even if it exchanges heat with air due to low temperature,
By performing heat exchange with the refrigerant flowing in the sub-evaporator 30, the refrigerant effectively takes in the heat of the engine cooling water and is heated (that is, the enthalpy is increased), and is returned to the compressor 2 and again. Since the refrigerant is pressurized by the compressor 2, the refrigerant discharged from the compressor 2 becomes a higher-temperature refrigerant,
It will be supplied to the sub capacitor 22. As a result, the air that has been heat-exchanged in the sub-condenser 22 has a higher temperature, so that a higher heating performance is exhibited and the immediate warming property is also improved. Moreover, when the heat-sensitive portion 27 of the second expansion valve 25 is provided at the outlet of the sub-evaporator 30 as described above, the flow rate of the refrigerant is adjusted by the temperature of the refrigerant after being heated by the sub-evaporator 30, When the sub-evaporator 30 is operated, a larger amount of refrigerant is circulated, and the heating performance is further enhanced.

In FIG. 1, the sub-evaporator 30 is provided between the suction side of the compressor 2 and the outlet of the front evaporator 13, but the present invention is not limited to this. Since the sub-evaporator 30 functions only during the heating operation as described later, it is sufficient that the sub-evaporator is installed between the suction side of the compressor 2 and the outlet of the rear evaporator 23.

During the heating operation, the refrigerant discharged from the compressor 2 usually flows only to the rear unit 20 through a circuit (heating circuit) to be described later, and the front unit 1
It does not flow to the 0 side. At this time, an electromagnetically operated on-off valve (hereinafter, referred to as a “first electromagnetic valve”) that controls whether the refrigerant that has exited the liquid tank 14 is guided to the front unit 10 side.
Reference numeral 16 is closed, and an electromagnetically operated on-off valve (hereinafter referred to as "second electromagnetic valve") 26 for controlling whether or not the refrigerant is guided toward the rear unit 20 is open. That is, at this time, the refrigerant flowing out of the compressor 2 is, as shown in FIG. 2, the four-way valve 4 → the bypass passage 6 → the first liquid tank 14 → the second liquid tank 14.
It flows through the solenoid valve 26 → the sub-condenser 22 → the second liquid tank 24 → the second expansion valve 25 → the rear evaporator 23 → the sub-evaporator 30 and returns to the compressor 2.

An electromagnetically operated hot water valve 17 is provided at the heater core 12 (for example, at the inlet side). During the heating operation, the hot water valve 17 is opened, so that hot water flowing out of the engine 1 is heated. 12
Has been introduced.

The sub-evaporator 30 (for example,
A water valve 31 whose opening can be adjusted by an actuator or the like, for example, is provided as a flow control valve on the hot water inlet side). During the heating operation, as described later, the water valve 31 according to the heat load state of the vehicle is provided. 31
Of the warm water flowing through the sub-evaporator 30 is controlled.

On the other hand, during the cooling operation, the refrigerant discharged from the compressor 2 usually flows to both the front unit 10 and the rear unit 20 through a circuit (cooling circuit) described later. At this time, the first solenoid valve 16 and the second solenoid valve 26 are both open. That is, at this time, the refrigerant flowing out of the compressor 2 is, as shown in FIG.
After flowing from the main condenser 3 to the first liquid tank 14 and branching therefrom to the front unit 10 side and the rear unit 20 side, they merge at the inlet of the sub-evaporator 30 and return to the compressor 2. More specifically, in the former, the refrigerant flowing out of the first liquid tank 14 flows through the first solenoid valve 16 → the first expansion valve 15 → the front evaporator 13, and then passes through the sub-evaporator 30 to the compressor 2. In the latter case, the refrigerant that has exited the first liquid tank 14 is supplied to the second solenoid valve 26 → the sub-condenser 22 → the second liquid tank 24 →
After flowing from the second expansion valve 25 to the rear evaporator 23, the flow returns to the compressor 2 via the sub-evaporator 30.

On the high pressure side of the refrigerant circuit, two pressure detecting means 18 and 28 for detecting the discharge pressure (Pd) of the compressor 2 are provided. For example, the first pressure detecting means 18 is provided in the first liquid tank 14 and the second pressure detecting means 28 is provided in the second liquid tank 24.
It is installed in. Each of the pressure detecting means 18 and 28 is composed of, for example, a so-called trinary-type pressure switch incorporating three diaphragms, or a pressure transducer (pressure sensor) for converting the detected pressure into a voltage value. When the discharge pressure of the compressor 2 rises, as described later, according to the output of the pressure detecting means 18 and 28 (compressor discharge pressure), the compressor 2
Various controls for lowering the discharge pressure of are performed. At this time, in the present invention, the pressure detecting means 18 or 28 to be operated is switched to one of the cooling operation and the heating operation (the pressure of the liquid refrigerant after passing through the condenser is used as the compressor discharge pressure). For). Specifically, during the cooling operation, the first pressure detecting means 1
8, the second pressure detecting means 2 during the heating operation.
8 output is used.

As described above, the refrigerant return passage 5 is provided between the outlet side (one of the outlet ports) of the four-way valve 4 and the suction side of the compressor 2. When the outside air temperature is low and the engine cooling water cannot be used immediately as a heat source for heating, the so-called sleeping refrigerant remaining in the main condenser 3 and the like is returned to the compressor 2, and high-performance heating is performed using a large amount of refrigerant. This is to make it possible.

In FIGS. 1 to 3, reference numeral 7 denotes an electric fan for cooling the main condenser 3, and reference numerals 40, 41, and 42 denote check valves for preventing flow in opposite directions.

Although not explicitly shown in FIGS. 1 to 3, preferably, an accumulator is provided between the sub-evaporator 30 and the compressor 2. Since the accumulator is a container having a relatively large capacity for storing the refrigerant, even if the refrigerant returns in a liquid state, it can be vaporized and returned to the compressor 2, thereby preventing damage to the compressor 2 due to liquid compression. can do.

Next, the operation will be described.

When the outside air temperature is low at the beginning of the heating operation, the temperature of the engine cooling water is low and cannot be used for heating immediately (in the case of the heater core 12). In addition, the refrigerant also lies inside the main condenser 3 and the like, and does not exist much in the compressor 2. When heating the rear seat in this state, first, the first solenoid valve 16 is closed,
The second solenoid valve 26 is set to the open state, the water valve 31 is set to the fully open state, and the four-way valve 4 is set to the state shown in FIG.

When the compressor 2 is turned on in this state,
The refrigerant mainly stored inside the main condenser 3 and the like is guided to the suction side of the compressor 2 through the four-way valve 4 and the refrigerant return passage 5 and is collected.

As a result, the compressor 2 is in an operation state in which a large amount of refrigerant can be discharged, and the high-temperature and high-pressure refrigerant discharged from the compressor 2 does not flow to the front unit 10 side, and the four-way valve 4 → the bypass passage 6 → the The first liquid tank 14 → the second solenoid valve 26 → the sub-condenser 22 → the second liquid tank 24 → the second expansion valve 25 → the rear evaporator 23 → the sub evaporator 30 and flows only to the rear unit 20 side and returns to the compressor 2. In this circulation process, the low-temperature and low-pressure refrigerant flowing into the sub-evaporator 30 is heated by heat exchange with the engine cooling water, becomes higher in temperature, is sucked into the compressor 2, and is compressed again. As a result, the refrigerant that has returned to the compressor 2 and is compressed again has a higher enthalpy (that is, a higher cycle balance) and is discharged at a higher temperature and a higher pressure. Moreover, in this case, the opening degree of the second expansion valve 25 (that is, the flow rate of the refrigerant) is adjusted by the refrigerant temperature at the outlet of the sub-evaporator 30 detected by the heat-sensitive part 27. When the refrigerant temperature rises due to heat exchange with the engine cooling water, the second
The degree of opening of the expansion valve 25 increases, and a larger amount of refrigerant circulates. Since the heating capacity (radiation performance) of the sub-condenser 22 is related to the temperature and the flow rate of the refrigerant, a higher heating performance is exhibited by increasing the temperature of the discharged refrigerant and increasing the flow rate. . Further, such a tendency is amplified with the passage of time, so that the so-called immediate warming property is also improved. That is, if the temperature of the engine cooling water rises while this operation is continued for a while, the amount of heat absorbed by the sub-evaporator 30 from the engine cooling water to the refrigerant itself increases, and is sucked into the compressor 2. As a result, the temperature of the refrigerant increases in a synergistic manner, so that the heating performance and the instantaneous heating can be greatly improved.

At this time, the air taken into the rear unit 20 is dehumidified and cooled in the rear evaporator 23, further heated in the sub-condenser 22, flows down, and is blown into the vehicle compartment from a predetermined outlet.
As a result, dehumidifying heating for heating dehumidified air is realized.

It is also possible to add a control to prevent air from passing through the sub-condenser 22 by an air mixing door (not shown) until the temperature of the blown air rises to some extent.

The heating of the rear seat has been described above. The heating of the front seat is performed exclusively by using the engine cooling water. For this reason, after the engine 1 is started, either the hot water valve 17 is closed until the engine cooling water rises to a level that can be used for heating, or air is prevented from passing through the heater core 12 by an air mixing door (not shown). Preferably, one or both controls are performed.

In the early stage of the heating operation, the number of times of the engine 1, that is, the number of revolutions of the compressor 2 sharply increases, for example, by depressing an accelerator at the time of rapid acceleration, and the discharge pressure of the compressor 1 sharply increases. In order to protect the compressor 2, it is necessary to perform control for lowering the discharge pressure of the compressor 2. However, since this is the same even when it is stable, it will be collectively described below. .

When the temperature of the engine cooling water rises to a certain extent and the temperature of the vehicle interior rises to a certain extent when the heating operation is stable , a predetermined heating performance can be obtained in accordance with the heat load condition of the vehicle, especially in the heating of the rear seat. Thus, for example, the opening degree of the water valve 31 is controlled by an actuator or the like to control the flow rate of the hot water flowing through the sub-evaporator 30.

FIG. 5 is a graph for explaining the relationship between the water valve opening and the heating performance when the hot water is stable.
As can be seen from the figure, when the hot water is stable, as the opening of the water valve 31 increases, the flow rate of the refrigerant circulating in the refrigeration cycle increases, the discharge pressure (Pd) of the compressor 2 increases, and the blowing air temperature increases. Rises. This principle has already been described. When the opening of the water valve 31 is increased, the sub-evaporator 30
The amount of heat exchange with the refrigerant increases due to an increase in the flow rate of hot water flowing through the sub-evaporator 30, and the refrigerant temperature at the outlet of the sub-evaporator 30 increases. As a result, the opening degree of the second expansion valve 25 increases, the flow rate of the refrigerant increases, and the discharge pressure of the compressor 2 increases with an increase in the temperature of the refrigerant sucked into the compressor 2. As a result, the heat radiation capacity of the sub-condenser 22 is increased, and the temperature of the blown air rises.

As a specific control, for example, when the heat load state (required heating capacity) of the vehicle is such that the amount of heat of the engine cooling water is not required, for example, when the outside air temperature is not so low, the water valve 31 is fully closed to prevent the engine cooling water from flowing into the sub-evaporator 30. Thus, the refrigerant returning to the compressor 2 is not unnecessarily heated by the sub-evaporator 30.

Conversely, when the vehicle has a very high thermal load (required heating capacity), such as when the outside air temperature is extremely low (overload), the water valve 31 is fully opened and the sub-evaporator 30 Make sure that a large amount of engine coolant flows in. As a result, the refrigerant returning to the compressor 2 is heated to the maximum by the sub-evaporator 30, and the maximum heating capacity of the system is exhibited.

In the intermediate stage, the opening degree of the water valve 31 is controlled so as to obtain a predetermined heating performance according to the heat load state of the vehicle, and the flow rate of the hot water flowing through the sub-evaporator 30 is controlled.

As described above, by controlling the opening of the water valve 31 in accordance with the heat load state of the vehicle, it is possible to bring out a detailed heating performance.

Next, the following measures are taken here as protection measures when the discharge pressure of the compressor 2 rises.

Embodiment 1: Here, ON / OFF control of the water valve 31 and ON / OFF control of the compressor 2 are performed according to the discharge pressure of the compressor 2.

FIG. 6 shows an example of the control characteristics. That is, before the ON / OFF control of the compressor 2 is performed, the output (compressor discharge pressure) of the pressure detecting means 28 in the second liquid tank 24 becomes, for example, 23 kg / cm ² G or more as the first set value. When this happens, the water valve 31 is fully closed (OFF), and when it falls below 20 kg / cm ² G as the second set value, the water valve 31 is fully opened (ON) again (note that the compressor discharge pressure is 20 kg / cm 2). ^{At about 2} G, it is assumed that the water valve 31 is in an overload state in which the water valve 31 should be fully opened in the above-described hot water flow rate control.)

In this overload state, as described above, the sub-evaporator 30 is normally operated with the water valve 31 fully opened, and the discharge pressure of the compressor 2 is relatively constant in the refrigeration cycle. High condition (2
0kg / cm ² G). In this state, when the water valve 31 is fully closed, the discharge pressure of the compressor 2 decreases (see FIG. 5), so that the pressure increase of the compressor 2 can be suppressed to protect it.

When the water valve 31 is fully closed, the discharge pressure of the compressor 2 decreases and the temperature of the blown air decreases at the same time (see FIG. 5). ON / OF
By appropriately setting the reference value for F, it was found that the change in the blown air temperature could be suppressed to such a degree that the occupant did not feel uncomfortable, and the comfort was not impaired. For example, in the case of the control characteristics shown in FIG.
The change of the blown air temperature due to ON / OFF of about 3 minutes (temperature rise) plus about 1 minute (temperature fall), about 1 minute
It was within 0 ° C.

Further, ON / OF of the water valve 31
As in the conventional case, ON / OFF control of the compressor 2 is also performed in preparation for a case where the compressor discharge pressure rises to an extent that the F control cannot cope with. Specifically, when the output (compressor discharge pressure) of the pressure detecting means 28 in the second liquid tank 24 rises to, for example, 27 kg / cm ² G or more as a reference value at which the compressor 2 should be stopped, the compressor 2 is stopped. (OFF), and when it falls below 20 kg / cm ² G, the compressor 2 is operated (ON) again.

The pressure detecting means 28 for performing this control may be a pressure switch of a trinary system or a pressure transducer (pressure sensor).
It is preferable to use the latter pressure transducer (pressure sensor) in consideration of the frequency, durability, and ease of changing the set value.

Therefore, according to the present embodiment, when the discharge pressure of the compressor 2 increases,
Before the N / OFF control, the water valve 3
Since the ON / OFF control of 1 is performed to lower the discharge pressure of the compressor 2, the operation frequency of the ON / OFF control of the compressor 2 when the pressure rises is reduced, and the drivability is improved. In addition, at this time, the temperature change of the blown air can be suppressed to such a small degree that the comfort of the occupant is not impaired.

Further, since the ON / OFF control of the water valve 31 is performed in addition to the ON / OFF control of the compressor 2, the protection means against the pressure increase is increased by one step, and the reliability is improved.

Note that the ON / OFF of the water valve 31
By changing the opening of the water valve 31 continuously according to the compressor discharge pressure instead of the OFF control,
It is also possible to suppress an increase in the pressure of the compressor 2. In this case, map data is also created in advance by experiment or the like in consideration of the compressor rotation speed (engine rotation speed) so that the change in blown air temperature is reduced. The pressure detecting means 28
A pressure transducer (pressure sensor) capable of continuous output is used.

Embodiment 2: Here, the opening / closing control of the first solenoid valve 16 and the ON / OFF control of the compressor 2 are performed in accordance with the discharge pressure of the compressor 2. At this time, the pressure detecting means 28 may be a pressure switch of a trinary system or a pressure transducer (pressure sensor).

FIG. 7 shows an example of the control characteristics. That is, before the ON / OFF control of the compressor 2 is performed, the output (compressor discharge pressure) of the pressure detecting means 28 in the second liquid tank 24 is, for example, 15.5 kg / cm ² G as the third set value. When the above is reached, the first solenoid valve 16 is opened, and 1 as the fourth set value is set.
When the pressure drops below 0 kg / cm ² G, the first solenoid valve 16 is closed again.

During the heating operation, as described above, since the refrigerant does not flow to the front unit 10 side, the first solenoid valve 16
Is closed (see FIG. 2). In this state, the first
When a part of the refrigerant flowing out of the liquid tank 14 flows to the front unit 10 side by opening the solenoid valve 16, the refrigerant flows into the front evaporator 13, so that the flow rate of the refrigerant to the rear unit 20 side is reduced. In addition, the refrigerant that cannot be completely condensed flows into the front evaporator 13 and the front evaporator 13 functions as a condenser, so that the compressor discharge pressure decreases.

Further, in preparation for a case where the compressor discharge pressure rises to an extent that the opening / closing control of the first solenoid valve 16 cannot cope with, the ON / OF of the compressor 2 is performed as in the conventional case.
F control is also performed. Specifically, the second liquid tank 24
Output of the pressure detection means 28 in the inside (compressor discharge pressure)
However, for example, when the compressor 2 rises to 27 kg / cm ² G or more as a reference value to be stopped, the compressor 2 is stopped (OFF), and when it falls below 21 kg / cm ² G, the compressor 2 is turned on again (ON). .

Therefore, according to the present embodiment, when the discharge pressure of the compressor 2 increases, the O
Since the opening / closing control of the first solenoid valve 16 is performed to reduce the discharge pressure of the compressor 2 before the N / OFF control is performed, the ON / O of the compressor 2 when the pressure rises is increased.
The operation frequency of the FF control is reduced, and the drivability is improved. Moreover, at this time, since the normal heating operation is continued on the rear unit 20 side, the heating function of the rear seat is not impaired.

Further, since the opening / closing control of the first solenoid valve 16 is performed in addition to the ON / OFF control of the compressor 2, the protection means against the pressure increase is increased by one step, and the reliability is improved.

Embodiment 3 Here, switching control of the four-way valve 4 and ON / OFF control of the compressor 2 are performed according to the discharge pressure of the compressor 2. At this time, the pressure detecting means 28 may be a pressure switch of a trinary system or a pressure transducer (pressure sensor).

FIG. 8 shows an example of the control characteristics. That is, before the ON / OFF control of the compressor 2 is performed, the output (compressor discharge pressure) of the pressure detecting means 28 in the second liquid tank 24 is, for example, 15.5 kg / cm ² G as the fifth set value. At this point, the four-way valve 4 is switched to allow the refrigerant to flow through the main condenser 3, and when it falls below 10 kg / cm ² G as the sixth set value, the four-way valve 4 is switched again to prevent the refrigerant from flowing to the main condenser 3. .

During the heating operation, as described above, no refrigerant is allowed to flow to the main condenser 3 (see FIG. 2). In this state, when the four-way valve 4 is switched so that the refrigerant discharged from the compressor 2 flows to the main condenser 3, heat exchange is performed with the outside air (low-temperature outside air) hitting the main condenser 3, so that the condensation capacity is increased. The compressor discharge pressure drops.

Further, in the case where the compressor discharge pressure rises to an extent that the switching control of the four-way valve 4 cannot cope with, the ON / OFF control of the compressor 2 is also performed as in the prior art. Specifically, the output (compressor discharge pressure) of the pressure detecting means 28 in the second liquid tank 24 is
For example, the compressor 2 is stopped (OFF) when it rises above 27 kg / cm ² G as a reference value at which the compressor 2 should be stopped, and the compressor 2 is turned on again (ON) when it falls below 21 kg / cm ² G.

Therefore, according to the present embodiment, when the discharge pressure of the compressor 2 increases, the O
Before the N / OFF control is performed, the switching control of the four-way valve 4 is performed to lower the discharge pressure of the compressor 2, so that the compressor 2 is turned ON / OF when the pressure is increased.
The operation frequency of the F control is reduced, and the drivability is improved.

Further, since the switching control of the four-way valve 4 is performed in addition to the ON / OFF control of the compressor 2, the protection means against the pressure increase is increased by one step, and the reliability is improved.

When cooling both front and rear seats, the first solenoid valve 16 and the second solenoid valve 26 are opened, the four-way valve 4 is in the state shown in FIG.
Is set to the fully closed state. When the temperature is to be adjusted for the front seat, the hot water valve 17 is opened.

When the compressor 2 is turned on in this state,
The refrigerant discharged from the compressor 2 flows to both the front unit 10 side and the rear unit 20 side. That is, as shown in FIG. 3, the refrigerant flowing out of the compressor 2 flows through the four-way valve 4 → the main condenser 3 → the first liquid tank 14, and branches therefrom to the front unit 10 side and the rear unit 20 side. After flowing, they merge at the inlet of the sub-evaporator 30 and return to the compressor 2. More specifically, in the former, the refrigerant flowing out of the first liquid tank 14 is supplied from the first solenoid valve 16 to the first expansion valve 1.
5 → After flowing to the front evaporator 13, it returns to the compressor 2 via the sub-evaporator 30, and in the latter, the refrigerant that has exited the first liquid tank 14 is
After flowing through the second solenoid valve 26 → sub-condenser 22 → second liquid tank 24 → second expansion valve 25 → rear evaporator 23, the compressor 2
Return to. In this circulation process, the sub-condenser 22 in the rear unit 20 is supplied with the liquid refrigerant already condensed and liquefied by the main condenser 3, so that the sub-condenser 22 has little ability as a heat exchanger. Further, at this time, since the water valve 31 is fully closed as described above to prevent the flow of the hot water into the sub-evaporator 30, the sub-evaporator 30 does not function, so that the temperature rise on the low pressure side is prevented. Therefore, the cooling performance is not impaired.

As a result, in the front seat, the air taken into the front unit 10 is cooled and dehumidified by heat exchange with the refrigerant in the front evaporator 13 to become cool air, and then the air mix door (not shown). ), The cool air and the hot air (air heated by the heater core 12) are mixed at an appropriate ratio to adjust the temperature, or are blown into the vehicle interior from a predetermined outlet without being mixed.

In the rear seat, the rear unit 2
The air taken in 0 is cooled and dehumidified by heat exchange with the refrigerant in the rear evaporator 23 to become cool air, and then cool air and hot air (sub-condenser) at an appropriate ratio by an air mixing door (not shown). Air heated at 22)
Are mixed and temperature-adjusted, or are blown into the vehicle compartment from a predetermined outlet without being mixed.

When cooling only the front seat, the first solenoid valve 16 may be closed, and when cooling only the rear seat, the second solenoid valve 26 may be closed.

As a protective measure when the discharge pressure of the compressor 2 rises, the ON / OFF control of the electric fan 7 according to the discharge pressure of the compressor 2 and the compressor 2 ON
/ OFF control is performed. At this time, as described above,
The control is performed by a signal from the pressure detecting means 18 in the first liquid tank 14. As in the case of the pressure detecting means 28 operating during the heating operation, the pressure detecting means 18 may be a trinary type pressure switch or a pressure transducer (pressure sensor).

FIG. 9 shows an example of the control characteristics. That is, first, ON / OFF of the compressor 2
Before performing the control, the output of the pressure detecting means 18 in the first liquid tank 14 (compressor discharge pressure)
However, for example, the electric fan 7 is turned on when the pressure becomes 15.5 kg / cm ² G or more, and the electric fan 7 is returned to the off state when the pressure becomes 10 kg / cm ² G or less. When the electric fan 7 is turned on, the amount of heat radiation in the main condenser 3 increases, so that the pressure of the refrigerant flowing out of the main condenser 3 decreases. Next, ON / OFF control of the compressor 2 is also performed in preparation for a case where the compressor discharge pressure rises to an extent that the ON / OFF control of the electric fan 7 cannot cope with.
Specifically, when the output of the pressure detecting means 18 (compressor discharge pressure) rises to, for example, 27 kg / cm ² G or more, which is a reference value at which the compressor 2 should be stopped, the compressor 2 is stopped (OFF), and 21 kg / cm ² When the pressure falls below cm ² G, the compressor 2 is turned on again (ON).

Although the above embodiment relates to an air conditioner for a vehicle having a first unit and a second unit, the present invention is not necessarily limited to only an air conditioner having such two units. Instead, any heat pump type air conditioner for a vehicle having a sub-evaporator can be applied regardless of the number of units.

The four-way valve 4 and the refrigerant return passage 5 are provided to return the stagnant refrigerant to the compressor 2.
The cooling / heating operation is not limited to this, and the cooling / heating operation may be performed without returning the stagnation refrigerant to the compressor 2. In this case, instead of the four-way valve 4, for example, 2
It is preferable to provide two on-off valves and the like at the inlet of the main condenser 3 and the bypass passage 6, respectively.

[0083]

As described above, according to the first and second aspects of the present invention, the opening of the flow control valve is controlled in accordance with the heat load state of the vehicle during the heating operation, so that the air flows to the sub-evaporator. The flow rate of the engine cooling water, that is, the amount of heat absorbed from the engine cooling water to the refrigerant is controlled, so that it is possible to bring out detailed heating performance according to the heat load state of the vehicle.

According to the third aspect of the present invention, in addition to the effect of the first aspect of the present invention, the ON / OFF control of the flow control valve is performed at the stage before the compressor is stopped during the heating operation, so that the comfort is improved. Thus, the compressor can be protected without impairing the drivability, and the drivability is improved because the operation frequency of the ON / OFF control of the compressor is reduced. Further, the number of protection means against the pressure increase is increased by one, and the reliability is improved.

According to the fourth aspect of the present invention, during the heating operation, the opening and closing control of the on-off valve is performed before the compressor is stopped, so that the compressor can be protected without repeating the ON / OFF of the compressor. , Because the frequency of ON / OFF control of the compressor is reduced,
Drivability is improved. Further, the number of protection means against the pressure increase is increased by one, and the reliability is improved.

According to the fifth aspect of the present invention, the switching control of the circuit switching valve is performed at the stage before the compressor is stopped during the heating operation, so that the compressor is turned on / off.
In addition to protecting the compressor without repeating the above, the operation frequency of the ON / OFF control of the compressor is reduced, so that the drivability is improved. Further, the number of protection means against the pressure increase is increased by one, and the reliability is improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a heat pump type air conditioner for a vehicle according to the present invention.

FIG. 2 is a schematic configuration diagram illustrating a state during a heating operation of the device.

FIG. 3 is a schematic configuration diagram showing a state of the apparatus during a cooling operation.

FIG. 4 is an external view showing a structure of a sub-evaporator.

FIG. 5 is a graph for explaining a relationship between a water valve opening and heating performance when hot water is stable.

FIG. 6 is a control characteristic diagram showing one embodiment of compressor protection control during a heating operation.

FIG. 7 is a control characteristic diagram showing another embodiment of the compressor protection control during the heating operation.

FIG. 8 is a control characteristic diagram showing still another embodiment of the compressor protection control during the heating operation.

FIG. 9 is a control characteristic diagram illustrating an example of compressor protection control during cooling operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Compressor, 3 ... Main condenser (1st condenser), 4 ... Four-way valve (circuit switching valve), 6 ... Bypass passage, 10 ... Front unit (1st unit), 11, 21 ... Ventilation path, 12: heater core, 13: front evaporator (first evaporator), 14, 24: liquid tank, 15, 25: expansion valve, 16: first solenoid valve (open / close valve), 18, 28: pressure detection means, 20: rear Unit (second unit), 22: sub-condenser (second condenser), 23: rear evaporator (second evaporator), 27: temperature sensing part, 30: sub-evaporator, 31: water valve (flow control valve).

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshio Ohashi 5-24-15 Minamidai, Nakano-ku, Tokyo Inside Calsonic Nick Kansei Corporation (72) Inventor Yuyoshi Tajima 5-24-15 Minamidai, Nakano-ku, Tokyo (72) Inventor Kaoru Kamiyama 5-24-15 Minamidai, Nakano-ku, Tokyo Inside Calso-Nic Kansei Corporation

Claims (5)

[Claims] An evaporator (13) constituting a refrigeration cycle together with a compressor (2) and a condenser (3) is connected to a sub-evaporator (30) capable of circulating engine cooling water at an outlet of the evaporator (23). In the heat pump type automotive air conditioner, the sub-evaporator (30) heats the refrigerant flowing into the sub-evaporator (30) using the engine cooling water and then returns the refrigerant to the compressor (2). Having a flow control valve (31) for controlling the flow rate of the engine coolant circulating through the sub-evaporator (30), during heating operation,
A heat pump type air conditioner for a vehicle, wherein an opening degree of the flow control valve (31) is controlled according to a heat load state of the vehicle. 2. A first unit (10) and a second unit (20) for respectively sending the introduced air toward a vehicle interior, and a downstream unit is provided in an air passage (11) of the first unit (10). In order from the side, a heater core (12) through which engine cooling water circulates,
A first evaporator (13) constituting a refrigeration cycle together with a compressor (2) and a first condenser (3) respectively disposed outside the first and second units (10, 20); A second condenser (22) and a second evaporator connected in parallel with the first evaporator (13) and in series with each other in order from the downstream side in the ventilation path (21) of the second unit (20). (23), and the compressor
(2) a refrigerant circuit for cooling operation for guiding the refrigerant discharged from the first condenser (3) to the first condenser (3);
A circuit switching valve (4) for switching a refrigerant circuit for heating operation which leads to a bypass passage (6) for bypassing (3);
And a sub-evaporator (30) connected to an outlet of the second evaporator (23) and capable of circulating the engine cooling water, provided outside the second unit (10, 20), and the sub-evaporator (30) In a heat pump type air conditioner for a vehicle that heats a refrigerant flowing into the sub-evaporator (30) by using the engine cooling water and then returns the refrigerant to the compressor (2), the sub-evaporator (30) It has a flow control valve (31) that controls the flow rate of circulating engine cooling water, and during heating operation,
A heat pump type air conditioner for a vehicle, wherein an opening degree of the flow control valve (31) is controlled according to a heat load state of the vehicle. 3. The flow control valve (31) is fully closed when the discharge pressure of the compressor (2) rises to a first set value smaller than a reference value at which the compressor (2) should be stopped. The heat pump type air conditioner according to claim 1, wherein the air conditioner is set to a fully open state when the air conditioner is set to a state and falls below a second set value smaller than the first set value. 4. A first unit (10) and a second unit (20) for sending air taken into the vehicle interior, respectively, and a downstream unit is provided in an air passage (11) of the first unit (10). In order from the side, a heater core (12) through which engine cooling water circulates,
A first evaporator (13) constituting a refrigeration cycle together with a compressor (2) and a first condenser (3) respectively disposed outside the first and second units (10, 20); A second condenser (22) and a second evaporator connected in parallel with the first evaporator (13) and in series with each other in order from the downstream side in the ventilation path (21) of the second unit (20). (23), and the compressor
(2) a refrigerant circuit for cooling operation for guiding the refrigerant discharged from the first condenser (3) to the first condenser (3);
A circuit switching valve (4) for switching between a refrigerant circuit for heating operation leading to a bypass passage (6) for bypassing (3);
And a sub-evaporator (30) connected to the outlet of the second evaporator (23) and capable of circulating the engine cooling water, provided outside the second unit (10, 20), and the sub-evaporator (30) By using the engine cooling water to heat the refrigerant flowing into the sub-evaporator (30), and then return to the compressor (2), in the heat pump type air conditioner for a vehicle, during the heating operation, the compressor ( When the discharge pressure of 2) rises to a third set value which is smaller than a reference value for stopping the compressor (2) or more, the first evaporator
(13) open the on-off valve (16) for controlling the introduction of the refrigerant, and when the discharge pressure of the compressor (2) drops below a fourth set value smaller than the third set value, the on-off valve (16) 16) A heat pump type air conditioner for a vehicle, wherein the air conditioner is returned to a closed state. 5. It has a first unit (10) and a second unit (20) for sending the air taken into the vehicle interior, respectively, and is provided in a ventilation path (11) of the first unit (10). In order from the side, a heater core (12) through which engine cooling water circulates,
A first evaporator (13) constituting a refrigeration cycle together with a compressor (2) and a first condenser (3) respectively disposed outside the first and second units (10, 20); In a ventilation path (21) of the second unit (20), a second condenser (22) and a second evaporator connected in parallel with the first evaporator (13) and connected in series with each other in order from the downstream side. (23), and the compressor
(2) a refrigerant circuit for cooling operation for guiding the refrigerant discharged from the first condenser (3) to the first condenser (3);
A circuit switching valve (4) for switching a refrigerant circuit for heating operation which leads to a bypass passage (6) for bypassing (3);
And a sub-evaporator (30) connected to the outlet of the second evaporator (23) and capable of circulating the engine cooling water, provided outside the second unit (10, 20), and the sub-evaporator (30) By using the engine cooling water to heat the refrigerant flowing into the sub-evaporator (30), and then return to the compressor (2), in the heat pump type air conditioner for a vehicle, during the heating operation, the compressor ( When the discharge pressure of 2) rises to a fifth set value or less that is smaller than a reference value for stopping the compressor (2), the circuit switching valve (4) is switched to the cooling operation side, and the compressor (2) When the discharge pressure falls below a sixth set value which is smaller than the fifth set value, the circuit switching valve (4) is returned to the heating operation side. .