JPH0355325B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a vehicle capable of operating a refrigeration cycle without freezing the evaporator even when the outside temperature is below a predetermined temperature, for example 0°C. The present invention relates to an evaporator freeze prevention structure for an air conditioner.

Conventional technology In the refrigeration cycle of conventional vehicle air conditioners, the compressor is controlled to be turned on at temperatures above 0°C and turned off at temperatures below 0°C.
(See "NISSAN Service Bulletin" No. 489, published by Nissan Motor Co., Ltd., September 2015, page V-87). Such control is
When the outside temperature drops below 0°C, the moisture in the air freezes on the surface of the evaporator fins as it passes through the evaporator, making it impossible for air to pass through the fins. This prevents a situation in which the refrigerant in the evaporator, which cannot be replaced, returns to the compressor in a liquid state and the compressor is damaged due to liquid compression.

Problems to be Solved by the Invention By the way, under low temperature and high humidity conditions such as during snowfall, the air blown out from the defroster outlet of a vehicle air conditioner towards the front window etc. is not only high temperature but also high temperature. It is preferable for the antifogging effect to be high temperature and dehumidified. However, in the conventional device, the compressor turns off when the outside temperature is below 0°C.
The reality is that it is not possible to dehumidify conditioned air using an evaporator, and anti-fogging is performed using air heated by a heater core installed in an air conditioner. It was expected that a vehicle air conditioner would be developed that could dehumidify conditioned air using an evaporator even under these conditions.

The present invention has been made in view of the above-mentioned conventional circumstances, and is an object for use in vehicles that enables the operation of a vapor compression type refrigeration cycle at low temperatures without the above-mentioned freezing of the evaporator or damage to the compressor due to liquid compression. This invention provides an evaporator freeze prevention structure for an air conditioner.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention opens and closes the inside air intake port and the outside air intake port, and adjusts the intake air amount from both the intake ports according to the degree of opening. A blower unit with an intake door to control the evaporator of the vapor compression refrigeration cycle,
A heater core that uses engine cooling water as a heat source and a heater unit that has an air mix door that controls the amount of air passing through the heater core are sequentially installed, and when the outside temperature falls below a predetermined temperature based on the output signal of the outside temperature sensor, In the vehicle air conditioner equipped with an evaporator antifreeze means for stopping the compressor of the refrigeration cycle, an intake temperature sensor is disposed in the ventilation path between the blower unit and the cooling unit, and a room temperature sensor is disposed inside the vehicle interior. On the other hand, when the outside temperature is below the predetermined temperature and the room temperature is above the predetermined temperature,
Based on the detection signal of the intake air temperature sensor, the intake door is driven at appropriate opening degrees in the direction in which the inside air intake opens until the intake air temperature in the ventilation path reaches or exceeds the predetermined temperature. A drive control means is provided which allows operation of the compressor in priority to the means.

Effect In the above configuration, when the air conditioner is operated under conditions where the outside temperature is below a predetermined temperature, for example below 0°C,
The antifreeze means attempts to execute control to stop the compressor based on the output signal of the outside temperature sensor. Then, the drive control means operates in synchronization with this, and based on the detection signal of the intake temperature sensor, the intake door is opened at appropriate opening degrees until the intake air temperature in the ventilation path reaches 0°C or higher, and the inside air intake port is expanded. drive in the direction. Therefore, a large amount of inside air having a higher temperature than the outside air is drawn into the blower unit through the inside air intake port, and the temperature of the intake air in the ventilation path gradually rises. Therefore, if the compressor is allowed to operate in priority to the control of the antifreeze means,
Air at a temperature of 0° C. or higher is supplied from the blower unit to the evaporator in the cooling unit, and the vapor compression refrigeration cycle can operate without freezing the evaporator.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. That is, as shown in FIGS. 1 and 2, the air conditioner main body 1 is constructed by sequentially connecting a blower unit 2, a cooling unit 3, and a heater unit 4. The blower unit 2 is provided with an inside air intake port 5, an outside air intake port 6, an intake door 7 that opens and closes both intake ports 5 and 6, and controls the amount of intake air according to the degree of opening, and a blower fan 8. . An actuator 11 for operating the intake door is linked to the intake door 7, and an intake door opening sensor 12 for detecting the door opening is provided. An intake temperature sensor 10 is disposed inside.

In the cooling unit 3, an evaporator 17 of a vapor compression refrigeration cycle 16 having a compressor 13, a condenser 14, and an expansion valve 15 shown in FIG. 3 is housed. 1 is installed as a drive source, and an electromagnetic clutch (not shown) inside that connects and disconnects from the drive source.
is provided.

Inside the heater unit 4, there is a heater core 18 that uses the engine cooling water as a heat source, and an air mix door 1 that controls the amount of air passing through the heater core 18.
9, 20, and 21 are provided. Note that the air mix doors 20 and 21 can be omitted if necessary. A defroster duct 22, a ventilator duct 23, and a foot duct 24 are formed on the peripheral wall of the heater unit 4 and communicate with an air outlet (not shown) provided in the vehicle interior. Each duct 22,2
A defroster door 25, a ventilator door 26, and a foot door 27 are pivotally supported at the base ends of the defroster doors 3 and 24, and a sub-defroster door 28 is provided below the defroster door 25. The intake temperature sensor 10 is connected to an input section of an arithmetic and control device 31 serving as a drive control means, together with an outside temperature sensor 29 and a room temperature sensor 37, via an A/D converter 30.
A refrigeration cycle switch 32 is further connected to the input section of the drive control device 31. This arithmetic and control device 31 has a function in which when the outside temperature detected by the outside air temperature sensor 29 is below a predetermined temperature, specifically below 0°C, the intake door 7 is opened so that the inside air inlet 5 is fully closed, as shown in FIG. An intake door opening calculation circuit 33 is provided which outputs the opening degree θ in the direction of expansion from the closed position, and adds and outputs the opening degree Δθ until the temperature detected by the intake air temperature sensor 10 reaches 0° C. or more. ing. On the output side of the intake door opening degree calculation circuit 33, the output value of the intake door opening degree sensor 12 is compared with the calculated values of the compressor ON-OFF circuit 34 and the intake door opening degree calculation circuit 33, which are means for preventing freezing of the evaporator. , an intake door opening comparison circuit 36 that outputs the differential opening is provided, and a drive circuit that outputs a drive signal to the intake door actuator 11 is provided on the output side of the intake door opening comparison circuit 36. 35 are provided.

Next, the operation of this embodiment configured as described above will be explained according to the flowchart shown in FIG. That is, when this system is started, flag A is reset (step), and when the air conditioner switch is turned on (step), the blower fan 8 is started, and the sensors 37,
From 29 and 20, room temperature Tr, outside temperature Ta, intake temperature
T _IN is input (step). Then, in the next step, it is determined whether the outside air temperature Ta is below 0°C, and if this determination is NO, that is, the outside air temperature
If Ta is 0°C or higher, there is no risk of freezing of the evaporator 17, so the compressor is ON-
The OFF circuit 34 turns on the compressor 13, the intake door 7 is normally controlled, and the flag A is reset (step). Here, the intake door normal control refers to automatic control if the intake door 7 is automatically controlled based on physical environmental factors related to temperature, or to the automatic control if the intake door 7 is manually controlled. This means allowing for flexible manual control. On the other hand, if the determination in the step is YES, that is, the outside air temperature Ta is 0° C. or lower, it is determined in the step that the refrigeration cycle switch 32 is ON, and if this determination is NO, the heat exchange of the heater core 18 is performed without operating the refrigeration cycle 16. If heat mode using only action is selected, evaporator 1
There is no need to control the intake door 7 to prevent the intake door 7 from freezing, and the intake door 7 is normally controlled as described above. And step determination is YES
If so, it is determined in step whether the room temperature Tr is 0° C. or higher. If this determination is NO, that is, if the room temperature Tr is 0°C or lower, no matter how much inside air is mixed, the temperature of the intake air in the ventilation path 9 supplied to the cooling unit 3 will not rise above 0°C. It is possible. Therefore, the intake door opening degree calculation circuit 33 does not calculate the opening degree of the intake door 7, and the compressor ON-OFF circuit 3
The compressor 13 is stopped by the OFF command signal from the compressor ON-OFF circuit 34 (step), and the refrigeration cycle 1 is started.
Freezing of the evaporator 17 due to the operation of the evaporator 6 is avoided. If the room temperature Tr is 0° C. or higher, it is further determined whether flag A has been reset (step), and if this determination is positive, the process of step is executed. That is, first, in the step, the intake door opening calculation circuit 3
3 is the detected temperature T _IN of the intake air temperature sensor 10 and a constant −K ₁
The opening degree θ is calculated from “−K ₁ ·T _IN ”. As described above and shown in FIG. 4, this opening degree θ varies from the fully closed state to the
is the opening degree of the intake door in the direction of expansion.
This opening degree θ is input to the drive circuit 35 via the intake door opening comparison circuit 34, and the intake door 7 is driven to the opening degree θ as the intake door operating actuator 11 operates (step).
As a result, inside air having a higher temperature than the outside air temperature is introduced into the blower unit 2 from the inside air intake port 5 according to the opening degree θ, and the intake air temperature inside the air blowing path 9 increases.
Therefore, in a further step, it is determined whether or not the intake temperature T _IN is 0°C or higher. If this determination is NO, that is, the intake temperature T _IN does not reach 0°C or higher at the opening angle θ, the intake temperature T _IN and the constant −K ₂ to “−K ₂・T _IN ”
Δθ is calculated (step), and the intake door 7 is driven to an opening degree that is the sum of Δθ, and the steps are continued until the step condition is satisfied.
, the loop is repeated. Through this loop, when the determination of the step is positive, the intake temperature supplied to the evaporator 17 from the ventilation path 9 is maintained at 0°C or higher, and therefore, when passing through the evaporator 17, the air Water can freeze on the surface of the fins of the evaporator 17, making ventilation impossible, and as a result, water can return to the compressor 13 in a liquid state inside the evaporator 17, causing damage to the compressor 13 due to liquid compression. Operation is permitted while being avoided. Therefore, dehumidification can be performed by the evaporator 17 even when the outside air temperature is below 0°C, and by blowing out the dehumidified air from the defroster outlet 25 toward the front window, etc., it is possible to eliminate low temperature and high humidity conditions such as during snowfall. Even at the bottom, it is possible to obtain an excellent anti-fog effect using the refrigeration cycle 16.

In the above embodiment, one condition (step) is that the refrigeration cycle switch 32 is ON, and the process proceeds to step ~ to control the intake door 7. A configuration in which the presence or absence of an output signal from a defrost switch, dew condensation sensor, etc. is determined in steps, and only when this determination is positive, the above control is executed, and flag A is set in steps as in this embodiment. It is also possible to do this.

Effects of the Invention As explained above, the present invention provides a vehicle air conditioner equipped with an evaporator freeze prevention means that stops the compressor when the outside temperature falls below a predetermined temperature, and a blower unit constituting the vehicle air conditioner. An intake temperature sensor is provided in the air passage between the blower and the cooling unit, and based on the temperature detected by the intake air temperature sensor, the intake door of the blower unit is closed to the inside air intake until the intake air temperature in the air passage reaches a predetermined temperature or higher. The compressor is controlled in the direction of expansion, and the compressor is allowed to operate with priority over the control of the antifreeze means. Therefore, even if the outside temperature is below a predetermined temperature, the air supplied to the evaporator is maintained at a predetermined temperature or higher by effectively utilizing the higher temperature inside air, and the evaporator freezes and the liquid refrigerant returns. A vapor compression refrigeration cycle can be operated without causing damage to the compressor or the like. Therefore, under conditions of low temperature and high humidity, such as during snowfall, it is possible to obtain an excellent anti-fogging effect by using conditioned air that is dehumidified by the evaporator and heated by the heater core.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention;
Figure 2 is a conceptual diagram of the air conditioner main body according to the same embodiment;
FIG. 4 is a system diagram of a vapor compression refrigeration cycle, FIG. 4 is an explanatory diagram showing the controlled opening of the intake door, and FIG. 5 is a flowchart showing the operation of the embodiment. 1...Air conditioner main body, 2...Blower unit,
5... Inside air intake port, 6... Outside air intake port, 7... Intake door, 9... Ventilation path, 10... Intake temperature sensor, 13... Compressor, 16... Vapor compression refrigeration cycle, 29... Outside temperature sensor, 31
... Arithmetic control circuit, 34 ... Compressor ON-
OFF circuit (evaporator freezing prevention means), 37...
...Room temperature sensor.

Claims (1)

[Claims] 1. A blower unit equipped with an intake door that opens and closes each intake port for inside air and outside air, a cooling unit that houses and arranges an evaporator of a vapor compression refrigeration cycle, a heater core that uses engine cooling water as a heat source, and the air flow rate through the heater core. and a heater unit having an air mix door for controlling the refrigeration cycle, and an evaporator antifreeze means for stopping the compressor of the refrigeration cycle when the outside temperature falls below a predetermined temperature based on the output signal of the outside temperature sensor. In the vehicle air conditioner, an intake air temperature sensor is disposed in the ventilation path between the blower unit and the cooling unit, and a room temperature sensor is disposed inside the vehicle, while the outside air temperature is below a predetermined temperature, and the room temperature is equal to or higher than the predetermined temperature, the intake door is moved in the direction in which the inside air intake opens, based on the temperature detected by the intake air temperature sensor, until the intake air temperature in the ventilation path reaches the predetermined temperature or higher. Along with driving,
An evaporator freeze prevention structure for a vehicle air conditioner, characterized in that a drive control means is provided that allows operation of a compressor with priority over the freeze prevention means.