JP2578107B2 - Control unit for automotive air conditioner - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner mounted on an automobile, and more particularly to a control device for controlling an air conditioner having a variable capacity compressor called a variable internal capacity type. .

2. Description of the Related Art Conventionally, as a vehicle air conditioner of this type, a compressor (compressor) that is drivingly connected to an on-vehicle engine via an electromagnetic clutch mechanism and a gas refrigerant discharged from the compressor are heated by air. A condenser (condenser) that cools by exchange and condenses to a liquid state, and an evaporator (evaporator) that evaporates the liquid refrigerant passing through the condenser and cools the vehicle interior by the heat of vaporization. When the evaporating temperature of the refrigerant drops below a predetermined temperature, this is detected by a frost switch, and the operation of the compressor is stopped by turning off the electromagnetic clutch mechanism. Have been.

That is, when the engine speed increases, the amount of refrigerant discharged from the compressor driven by the engine increases, and a large amount of refrigerant circulates in the refrigerant circuit. Since the load is substantially constant, the capacity becomes surplus, and the drive of the compressor is stopped to eliminate this surplus portion.

However, in that case, from the viewpoint of reducing the driving force for driving the compressor of the engine and improving the EER (energy consumption efficiency), rather than temporarily stopping the operation of the compressor and restarting it afterwards, the compressor is not used during that time. It is more preferable to continue the operation while reducing the capacity of the fuel cell from the steady state. For example, among compressors, condensers and evaporators, the dependence of these devices on the coefficient of performance shows that the smaller the capacity of the compressor, the lower the work capacity of the compressor itself, but the relative contribution of the condenser and evaporator. And the overall coefficient of performance increases. In other words, although the work capacity of the compressor is reduced, the overall enthalpy is equal, and the EER is increased.

Therefore, as a compressor that satisfies such requirements,
Hitherto, as disclosed in Japanese Patent Application Laid-Open No. Sho 60-261721, a compressor with a variable internal capacity has been proposed. this is,
When the compressor capacity becomes excessive, a part of the refrigerant sucked into the compressor body is bypassed from the middle of the compression stroke and returned to the suction side, so that the capacity of the compressor can handle the heat load in the vehicle compartment Is controlled automatically.

(Problems to be Solved by the Invention) On the other hand, in the air conditioner equipped with the proposed internal capacity variable compressor, the capacity of the compressor is automatically controlled to a capacity corresponding to the heat load in the vehicle compartment.
The following problems occur.

For example, after a long time has passed since getting off the vehicle, the temperature in the vehicle interior has risen to a high temperature, especially when the vehicle is parked under the scorching sun in summer. In such a situation, there is a demand for immediately operating the air conditioner immediately after getting on the vehicle to lower the room temperature to a comfortable temperature at once. However, when the internal capacity variable compressor is used, when the room temperature decreases to a certain level, the internal control state is automatically started at that point,
It becomes difficult to rapidly cool the vehicle interior, and so-called cool-down performance deteriorates.

(Objects of the Invention) The present invention has been made in view of the above points, and has as its object, in addition to the original automatic internal capacity control in the variable internal capacity compressor as described above,
An object of the present invention is to improve the cool-down performance of an air conditioner for a vehicle while taking advantage of the characteristics of a variable internal capacity compressor by appropriately controlling the capacity from outside the compressor according to the external conditions.

(Means for Solving the Problems) In order to achieve this object, the solution of the present invention detects the temperature of the interior of the vehicle compartment and the temperature of the evaporator of the air conditioner. In other words, when the capacity of the air conditioner has not yet reached a surplus state and the vehicle cabin is under cooling conditions, the internal capacity control of the compressor is temporarily prohibited, and the capacity is fixedly held at the maximum capacity. It was made.

Specifically, the configuration of the present invention is as shown in FIG.
A suction port 21 for sucking the refrigerant, and a discharge port 22 for discharging the refrigerant that has been sucked from the suction port 21 and passed through the compression stroke
An air conditioner having a variable displacement compressor 2 driven by an engine 12 mounted on an automobile, comprising a variable displacement mechanism 50 for controlling a discharge amount of the coolant in accordance with a suction pressure of the refrigerant drawn from the suction port 21. Assume the device.

In the automotive air conditioner, the compressor 2 is provided with a capacity setting mechanism 51 for stopping the operation of the variable capacity mechanism 50 to maintain the capacity of the compressor 2 at a maximum.

Also, room temperature detecting means 101 for detecting the temperature T _R of the vehicle interior
If, it provided an evaporator temperature detecting means 102 for detecting the evaporation temperature T _E of the refrigerant in the evaporator 6 of the air conditioner.

Furthermore, the room temperature and subjected to the output of the evaporation temperature detection means 101 and 102, when the refrigerant evaporation temperature T _E in and the evaporator 6 at a temperature T _R of the passenger compartment than a set value is a predetermined value or more, the capacity of the compressor 2 Control means 104 is provided for controlling the operation of the setting mechanism 51 so as to maintain the capacity of the compressor 2 at the maximum capacity state.

The (effect) In this configuration, in the present invention, by room temperature detecting means 101 is a temperature T _R of the passenger compartment, also the evaporation temperature T _E of the refrigerant in the evaporator 6 of the air conditioner are respectively detected by the evaporation temperature detection means 102, the Room temperature and evaporation temperature detection means 101, 10
The control unit 104 which receives the second output, the detected room temperature T _R and the refrigerant evaporation temperature T _E is compared with the comparison value of each. Then, it is determined that the room temperature T _R is lower than the set value or the refrigerant evaporation temperature T _E in the evaporator 6 is lower than the predetermined value, not in conditions to be cool the vehicle interior,
The internal capacity of the compressor 2 is controlled.

On the other hand, when the refrigerant evaporation temperature T _E in and the evaporator 6 at room temperature T _R is over the set value is a predetermined value or more is determined to be in the condition to be rapidly cool the vehicle interior, internal capacity control of the compressor 2 Are prohibited, and the capacity is forcibly fixed and held at the maximum capacity by the operation of the capacity setting mechanism 51. By fixed holding of the maximum capacity of the compressor 2,
The amount of refrigerant discharged from the compressor 2, that is, the amount of refrigerant circulated in the refrigerant circuit increases, so that the cool-down performance of the air conditioner can be significantly improved.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

FIG. 2 shows the overall configuration of the embodiment of the present invention.
Is an air conditioner installed in the automobile, and the air conditioner 1
The compressor 2 (compressor), which is drivingly connected to the vehicle-mounted engine 12 via an electromagnetic clutch mechanism 13 and a power transmission belt 14, and is disposed at the front end of the engine room of the vehicle body. A condenser 3 (condenser) for cooling and condensing into a liquid refrigerant, a receiver tank (liquid receiver) for storing the liquid refrigerant, and an expansion valve with an adjustable opening that decompresses and expands the liquid refrigerant to a pressure suitable for vaporization. 5 (expansion valve) and an evaporator 6 (evaporator) which is disposed in the vehicle interior, vaporizes the liquid refrigerant and cools the air in the vehicle interior by the heat of vaporization.
Are connected by a refrigerant pipe 7 to form a refrigerant circuit 8. Reference numeral 9 denotes a temperature sensing tube attached to a refrigerant pipe 7 returning from the evaporator 6 to the compressor 2. The temperature sensing tube 9 is connected to the expansion valve 5 via a heat transfer tube 10, and evaporates the evaporator 6. The opening of the expansion valve 5 is automatically adjusted so that the temperature of the gas refrigerant thus obtained becomes constant. Reference numeral 11 denotes a fan attached to the evaporator 6.

The compressor 2 is composed of a vane type variable displacement compressor. The basic structure of the variable displacement compressor 2 is the same as that of a normal vane compressor. That is, the main body 20 of the compressor 2 is airtightly joined to a ring-shaped side housing 23 and front and rear surfaces of the side housing 23 as shown in an enlarged detail in FIG. Front and rear housings 25 and 26 forming a columnar working chamber 24, and a cylindrical rotor 27 rotatably fitted in the working chamber 24 of the side housing 23 so as to be offset with respect to the center of the working chamber 24. And a pair of through vanes 28, 28, which are supported by the rotor 27 so as to be able to protrude and retract from the outer peripheral portion thereof, and whose end portions slidably contact the inner peripheral wall of the working chamber 24 to partition the working chamber 24, The suction chamber 25 has a suction port 21 for sucking the refrigerant into the working chamber 24 and a suction chamber 29 communicating with the suction port 21. The side housing 23 has a discharge port 22 for discharging the refrigerant that has undergone the compression stroke, and the rear housing 26 has a discharge chamber (not shown) communicating with the discharge port 22. Furthermore, the rotor
The rotation shaft 31 of the motor 27 is connected to the electromagnetic clutch mechanism 13. When the electromagnetic clutch mechanism 13 is turned on, the output of the engine 12 drives the rotor 27 to rotate. Vanes 2 in the working chamber 24
By gradually decreasing the volume of the part partitioned by 8 and 28, the gas refrigerant sucked from the suction port 21 of the side housing 23 is compressed and discharged from the discharge port 22.

In this basic configuration, a spool valve 32 is provided in the front housing 25 of the compressor body 20. A pressure regulator 40 composed of a needle valve is attached to a lower portion extending over both the side housing 23 and the rear housing 26.

As shown in FIG. 4, the spool valve 32 is slidably fitted in a cylindrical valve housing 33 and the valve housing 33, and the housing 33 is provided in a spring chamber 35 and a pressurizing chamber 36. A pressurizing chamber 36 is provided between the front housing 25 and the side housing 25 in the compressor body 20 through a port 33a of the valve housing 33 and a communication passage 37 connected to the port 33a.
The internal pressure of the gas refrigerant is set to a pressure approximately halfway between the suction pressure and the discharge pressure of the gas refrigerant. A spring 38 for urging the valve element 34 toward the pressurizing chamber 36 is compressed in the spring chamber 35, and the spring chamber 35 communicates with the suction chamber 29 in the front housing 25 via a port 33b. Have been. Further, the valve housing 33 has four bypass holes 39a to 39b at an intermediate portion of a sliding range of the valve body 34 inside the bypass hole. 39a, 39a (39b, 39b) are arranged in series in the center line direction of the housing 33, and are opened. The bypass holes 39a, 39a located on one side (the right side in FIG. 3) of the housing 33 are provided in the working chamber. In the part corresponding to the middle of the refrigerant compression process at 24, the other side (same left side) bypass hole
39b, 39b communicate with the suction chamber 29, respectively, and bypass holes 39a, 39
b and the spring chamber 35 located between the bypass holes 39a and 39b.
The bypass passages 39, 39 for bypassing the refrigerant to the suction chamber 29 (suction side) in the middle of the compression process of the refrigerant compressed in the working chamber 24 are formed by a part of the refrigerant. And
The urging force of the intermediate pressure in the pressurizing chamber 36 against the valve body 34 is applied to the refrigerant suction pressure in the spring chamber 35 by the spring inside the spring.
When it is larger than the biasing force obtained by adding the spring force of 38,
By moving 34 downward in FIG.
While closing the bypass passages 39, 39 by closing 39a-39b,
Conversely, when it is small, the valve body 34 is moved upward in the figure to open the bypass holes 39a-39b and open the bypass passages 39,39.

On the other hand, the pressure regulator 40 includes a valve housing 44 in which first and second two pressure chambers 42 and 43 communicating with each other through a valve port 41 are formed, and the valve port 41 is provided in the valve housing 44. Valve body 45 fitted so that it can be opened and closed
And fitted in the second pressure chamber 43 of the valve housing 44,
A diaphragm 46 for partitioning the second pressure chamber 43 into a suction pressure chamber 43a and an atmospheric pressure chamber 43b. The diaphragm 46 is integrally connected to the valve body 45 via a rod 47. In the atmospheric pressure chamber 43b, the diaphragm 46 is connected to the valve opening direction of the valve body 45 (the valve body 45 is connected to both the first and second pressure chambers 4).
The spring 48 is biased in the direction of communicating the 2,43). The first pressure chamber 42 is connected to the communication passage 37.
(A predetermined gap between the front housing 25 and the side housing 23 in the compressor body 20)
The suction pressure chamber 43a of the second pressure chamber 43 is communicated with the suction chamber 29, the atmospheric pressure chamber 43b of the second pressure chamber 43 is open to the atmosphere, and the suction pressure chamber 43a for the diaphragm 46 is opened. When the biasing force due to the refrigerant suction pressure in the chamber is greater than the biasing force obtained by adding the spring force of the spring 48 therein to the atmospheric pressure in the atmospheric pressure chamber 43b, the diaphragm 46 is moved downward in FIG. The valve port 41 is closed by a valve body 45 integrated with the valve body 46, and the communication between the first pressure chamber 42 and the suction chamber 29 is cut off. On the other hand, when it is small, the diaphragm 46 is moved upward in FIG. The valve port 41 is opened to allow the first pressure chamber 42 and the suction chamber 29 to communicate with each other. Therefore, the spool valve 32 and the pressure regulator 40 automatically control the opening and closing of the bypass passages 39 and 39 in accordance with the refrigerant suction pressure so that the refrigerant suction pressure of the compressor body 20 is kept substantially constant. When the rotational speed (engine speed) of the second engine 2 is low and its capacity is low, the pressure regulator 40 is closed and the bypass passages 39, 39 are closed by increasing the pressure in the pressurizing chamber 36 of the spool valve 32. , Compressor 2
While the capacity of the compressor 2 is maintained at the maximum capacity, when the capacity of the compressor 2 increases due to an increase in the rotation speed, the suction chamber
The pressure in the pressure regulator 40 is opened by the pressure drop in 29, and the pressure in the pressurizing chamber 36 in the spool valve 32 is reduced in accordance with the valve opening operation to move the valve body 34 upward in the drawing, so that the bypass passage By opening 39, 39 to bypass the gas refrigerant to the suction side, the compressor 2
So that its capacity decreases as its rotation speed increases,
That is, the variable displacement mechanism 50 is configured to eliminate the surplus capacity when the capacity of the compressor 2 is larger than the heat load in the vehicle compartment.

Further, the first pressure chamber of the pressure regulator 40
A normally open solenoid valve SV that opens and closes the communication passage 49 is provided in a communication passage 49 that communicates the communication passage 42 with the communication passage 37.When the solenoid valve SV is in an open state, the variable displacement mechanism 50 is operated. While the compressor 2 is in the internal capacity control state, when the solenoid valve SV is closed, the operation of the variable capacity mechanism 50 is stopped and the suction chamber 29 is stopped.
By balancing the internal pressure and the intermediate pressure, the valve body 34 of the spool valve 32 is positioned at the lower end position in the drawing, and the bypass passages 39, 3
A capacity setting mechanism 51 is configured such that the capacity of the compressor 2 is fixed to the maximum capacity by keeping the bypass amount of the refrigerant at zero while maintaining the fully closed state of the compressor 9.

Then, as shown in FIG. 2, the operation of the solenoid valve SV is controlled by the control unit 100. The control unit 100, a room temperature detecting thermistor 101 as a room temperature detecting means for detecting the temperature T _R of the passenger compartment,
Evaporation temperature T _E of the refrigerant in the evaporator 6 of the air conditioner 1
An evaporator temperature detecting thermistor 102 as evaporation temperature detection means for detecting is disposed in the vehicle interior, each output signal of the room temperature setting device 103 for setting the room temperature T _T of the driver or the like is desired by a manual operation Has been entered.

Here, according to FIG.
A processing procedure of a signal processed in 0 will be schematically described.

First, in the first step S1 after the ON operation of the operation switch (not shown) of the air conditioner ₁ , the room temperature T _R detected by the room temperature detection thermistor 101 and the set room temperature T _T set by the room temperature setting device 103. Compare the magnitude of
Proceeds to step S ₂ when YES of _{T R} ≧ T T, turn the temperature T _E of the evaporator 6 detected by the evaporator temperature detecting thermistor 102 to a predetermined temperature as the reference
Compare the magnitude with T _E ′ (for example, 0 ° C.), where T _E ≧ T _E ′
When YES is determined, the solenoid valve SV is closed,
The maximum displacement operation of the compressor 2 is performed by stopping the operation of the variable displacement mechanism 50.

On the other hand, when the determination in step S ₂ is NO in T _E <T _E 'opens the solenoid valve SV proceeds to step S _4, performs the capacity control operation with respect to the compressor 2 by the operation of the variable capacity mechanism 50. Thereafter, at step S _5, step S ₁
Similarly, performs comparison between set room temperature T _T and the detected room temperature T _R again, the process proceeds to step S ₆ when the determination is YES at T _R ≧ T _T, similarly to the step S ₂ and, 'performs comparison between, this determination is T _E ≧ T _E' temperature T _E and the predetermined temperature T _E of the evaporator 6 when YES in continues the capacity control operation of the compressor 2 returns to the step S _4. Also, T _E
<When the NO in T _E ', the determination of step S _1, S ₅ proceeds to step S ₇ with if NO, respectively, to stop the operation for the protection of such compressor 2. This step
After S _7, a predetermined time is determined whether the elapsed in step S _8, after a predetermined time, the process returns to step S ₁ by operating the compressor 2 again.

Therefore, in the present embodiment, the steps in the above flow
The S _1, S _2, receives the outputs of both thermistors 101, 102 and room temperature setting device 103, the set value T _T Thus room temperature setting device 103 is a temperature T _R of the passenger compartment and refrigerant evaporation in the evaporator 6 When the temperature T _E is equal to or higher than the predetermined value T _E ′, a control means 104 is configured to operate the capacity setting mechanism 51 of the compressor 2 to control the compressor 2 so as to maintain the compressor 2 in the maximum capacity operation state.

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

Basically, the compressor 2 operates in accordance with the ON operation of the operation switch of the air conditioner 1, and the gas refrigerant discharged from the compressor 2 is condensed by the condenser 3 to become a liquid refrigerant. After expansion at 5, evaporator 6 vaporizes and then is sucked into compressor 2, and the interior of the vehicle is cooled by the heat of vaporization of the refrigerant at evaporator 6.

In in operation such air conditioner 1, the room temperature detecting thermistor 101 is a temperature T _R of the passenger compartment, also the evaporation temperature T _E of the refrigerant in the evaporator 6 are detected respectively by the evaporator temperature detecting thermistor 102, these thermistors 101 and 102 Is input to the control unit 100 together with the setting signal of the room temperature setting device 103. And
In this control unit 100 along with the room temperature T _R is compared with the set value T _T, the temperature T _E of the evaporator 6 is compared with a predetermined value T _E ', or room temperature T _R is lower than the set value T _T, or when the temperature T _E of the evaporator 6 is lower than the predetermined temperature T _E ', the electromagnetic valve SV in the compressor 2 is kept opened, the compressor 2 is operated at capacity control state by the operation of the variable capacity mechanism 50 . That is,
When the rotation speed of the compressor 2 is low and its capacity is low, the pressure regulator 40 is closed, and the bypass passages 39, 39 are closed by the increase in the pressure in the pressurizing chamber 36 of the spool valve 32. While the capacity is maintained at the maximum capacity, if the capacity of the compressor 2 increases due to an increase in the rotation speed, the suction chamber
Pressure regulator 40 due to pressure drop in 29
Is opened, and the spool valve 32
The pressure in the pressurizing chamber 36 decreases, the valve body 34 moves to open the bypass passages 39, 39, and the gas refrigerant is bypassed inside the compressor 2 to the suction side.
The capacity of the compressor 2 is controlled so as to decrease as the number of rotations increases.

On the other hand, when the room temperature T _R is equal to or higher than the set value T _T and the temperature T _{E of the} evaporator 6 is equal to or higher than the predetermined temperature T _E ′, the driver requests that the passenger compartment be rapidly cooled. The solenoid valve SV is closed, the operation of the variable displacement mechanism 50 is stopped, and the suction chamber 29 is stopped.
Due to the balance between the internal pressure and the intermediate pressure, the valve element 34 of the spool valve 32 is positioned at the lower end position in FIG.
There is no bypass to the side, which fixes the capacity of the compressor 2 to the maximum capacity. By fixing and holding to the maximum capacity of the compressor 2, the temperature T _E of the evaporator 6 is lower than the predetermined temperature T _E ', the compressor 2 moves inside the capacity control described above. FIG. 6 illustrates the drop characteristic at room temperature in this case. In the drawing, the solid line indicates the characteristics of the example of the present invention, the broken line indicates the characteristics of the conventional example in which only the internal control of the compressor 2 is performed, and the one-dot chain line indicates the characteristics of the case of a normal compressor without a variable displacement mechanism. I have.

Thus, in this way the air conditioning system 1 having an internal capacity variable type compressor 2, at room temperature T _R is set value T _T or more, and when the temperature T _E of the evaporator 6 is not less than the predetermined value T _E 'from the outside of the compressor 2 In order to forcibly prohibit the internal capacity control and fix the compressor 2 to the maximum capacity state, the room temperature is rapidly cooled in response to a driver's request without reducing the capacity due to the maintenance of the internal capacity control. As a result, the cool-down performance of the air conditioner 1 can be improved.

In the above-described embodiment, a through-vane compressor is used as the variable displacement compressor 2. However, other types of variable displacement compressors, such as a swash plate compressor, may be used.

(Effect of the Invention) As described above, according to the present invention, in a vehicle air conditioner, a compressor driven by an on-vehicle engine can be selected from a variable capacity operation state and a maximum capacity operation state according to the suction pressure of refrigerant. Variable capacity compressor, when the temperature in the vehicle compartment is equal to or higher than the set value and the refrigerant evaporation temperature in the evaporator of the air conditioner is equal to or higher than a predetermined value,
By prohibiting the internal capacity control of the compressor and holding the capacity fixed at the maximum capacity state,
It is possible to improve the cool-down performance by keeping the capacity of the air conditioner at the maximum when a cool-down operation is requested while utilizing the automatic control of the capacity by the variable internal capacity compressor.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 and the following drawings show an embodiment of the present invention, FIG. 2 is an overall configuration diagram, FIG. 3 is an expanded sectional view showing a variable displacement mechanism of a compressor, FIG. 4 is a schematic sectional view thereof, and FIG. FIG. 6 is a flowchart showing a control procedure in the control unit, and FIG. 6 is a characteristic diagram showing a cool-down characteristic of the air conditioner. DESCRIPTION OF SYMBOLS 1 ... Air-conditioning apparatus, 2 ... Compressor, 6 ... Evaporator, 12 ... Engine, 21 ... Suction port, 22 discharge port, 32 ... Spool valve, 39 ... Bypass passage, 40 ... Pressure regulator, 50 ...... variable capacity mechanism, SV ...... solenoid valve, 51 ...... capacity setting mechanism, 100 ...... control unit, 101 ...... room temperature detecting thermistor, 102 ...... evaporator temperature detecting thermistor 104 ...... control unit, T _R ...... Room temperature, T _T …… Set temperature, T _E …… Evaporation temperature of refrigerant in the evaporator, T _E ′ …… Predetermined value.

Claims (1)

(57) [Claims] 1. A suction port for sucking a refrigerant, a discharge port for discharging a refrigerant that has been sucked from the suction port and passed through a compression stroke, and a variable displacement mechanism that controls a discharge amount of the refrigerant according to a suction pressure of the refrigerant. In an air conditioner having a variable capacity compressor driven by an engine mounted on an automobile, the compressor includes a capacity setting mechanism that stops the variable capacity mechanism and holds the capacity of the compressor to a maximum, Room temperature detecting means for detecting the temperature in the cabin, evaporating temperature detecting means for detecting the evaporating temperature of the refrigerant in the evaporator of the air conditioner, and the output of both detecting means, the temperature in the cabin is equal to or higher than the set value. And control means for operating the compressor capacity setting mechanism when the refrigerant evaporation temperature in the evaporator is equal to or higher than a predetermined value. Control device for a motor-vehicle air-conditioning apparatus according to claim.