JP3306880B2 - Vehicle air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for a vehicle, in which refrigerant compression is performed by a variable capacity compressor, and an air conditioning temperature is controlled by variably controlling a discharge capacity of the compressor.

[0002]

2. Description of the Related Art In a vehicle air conditioner, a refrigerant is compressed by a compressor, and the refrigerant compressed by the compressor is supplied to an evaporator via a condenser, so that air sent into the vehicle compartment is removed. It is configured to cool. In this case, a variable displacement compressor whose discharge capacity is variably controlled is used as the refrigerant compressor.

In such an air conditioner capable of variably controlling the capacity of the refrigerant compressor, the temperature control means for controlling the temperature of the air blown into the vehicle compartment to the target temperature is controlled by the capacity of the refrigerant compressor. PID control of the variable mechanism, and an air mix door (hereinafter referred to as A / M door) set in an air passage to which the output air from the evaporator is supplied
Thus, the temperature of the blown air is adjusted.

[0004] In order to secure the stability of the temperature behind the evaporator in a steady state, it is conceivable to reduce the response of the refrigeration cycle. However, if the constant of the PID control of the compressor capacity is fixed in accordance with this response, the A / M door is set to the coolest state, for example, in a state where there is no room to operate this door, A quick response cannot be made when changing the temperature of the air blown into the room.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and enables stable temperature control to be easily performed in a steady state, and also enables the A / M door to operate within an operating range. To provide a vehicle air conditioner in which the responsiveness of temperature control can be set according to the situation so that the temperature of the air blown into the vehicle compartment can be variably controlled with a quick response even when there is no room. Is what you do.

[0006]

An air conditioner for a vehicle according to the present invention comprises a refrigeration cycle using a refrigerant compressor capable of variably controlling a discharge capacity, and a proportional and integral control of a variable capacity mechanism of the compressor. The control is performed based on the equation, and the proportional constant of the control equation is set in accordance with the opening of the A / M door.

[0007]

In the vehicle air conditioner thus configured,
In a state where the opening degree of the air mix door is large and there is room for the movement, the proportional constant and the proportional constant of the integral control formula are set small. And, for example, in the state of the coolest (Max Cool) state and the opening degree of the air mix door is small,
The proportional constant for controlling the compressor capacity and the proportional constant of the integral control formula are set large. The control responsiveness of the air temperature in the passenger compartment is set to be quick.

[0008]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the air-conditioning air passage.
An evaporator 12 (heat exchanger) constituting a heat exchanger is set in the inside of the heat exchanger 11, and a blower is provided upstream of the evaporator 12.
13 is set. This blower 13 is an inside / outside air switching damper.
The outside air or inside air switched and selected in 14 is sucked in and supplied to the evaporator 12.

A heater 15 is provided downstream of the evaporator 12 in the air passage 11 so as to close a part of the passage 11. The heater 15 is further provided with an A / M 16, and the cooled air that has passed through the evaporator 12 is sent rearward with or without passing through the heater 15.

That is, the ratio of the air passing through the heater 15 is set by the A / M door 16.
The mixing ratio of the air cooled by the evaporator 12 and the air heated by the heater 15 is selected by the A / M door 16, and the temperature of the blown air is adjusted. And this A
The air whose temperature has been adjusted by the / M door 16 is supplied to an upper outlet 17 and a lower outlet 18 into the vehicle cabin. The amount of air blown from each of the outlets 17 and 18 is as follows.
It is controlled by the blowout mode switching damper 19.

The refrigerant compressor 20 constituting the refrigeration cycle includes:
For example, the compressor is configured to have a variable capacity type having a variable capacity mechanism 201 such as an electromagnetic valve. The refrigerant compressed by the compressor 20 is supplied to the evaporator 12 via the condenser 21 and the receiver 22. Then, the output refrigerant from the evaporator 12 is returned to the compressor 20.

An air conditioner having such a refrigeration cycle is controlled by a control device 23 constituted by a computer or the like. The control device 23 is supplied with detection signals from an inside air sensor 24 for measuring the temperature of the vehicle interior air, an outside air sensor 25 for measuring the temperature of the air outside the vehicle interior, and a solar radiation sensor 26 for measuring the amount of solar radiation. The temperature information set in the container 27 has been input.

On the air outlet side of the evaporator 12, a post-heat exchanger temperature sensor 28 for measuring the temperature behind the heat exchanger is provided, and the measured temperature information TE is inputted to the control device 23,
Further, information TEO from the heat exchanger rear target temperature setting unit 29 is also input.

The control unit 23 controls the compressor
20 capacity variable mechanism 201 and blower control circuit
131, and the inside / outside air switching damper 14,
Servo motors 141, 161, and 191 that respectively drive the A / M door 16 and the blowout mode switching damper 19 are controlled.

In the air conditioner constructed as described above, the detection signal Tr from the inside air sensor 24, the detection signal Tam from the outside air sensor 25, the detection signal Ts from the solar radiation sensor 26, and the temperature information set by the temperature setting unit 27 In the control device 23 in which Tset is taken in, the required blowing temperature TAO is calculated according to the equation (1).

TAO = Kset · Tset−Kr · Tr−Kam · Tam−Ks · Ts + C (1) where Kset is a set temperature gain, Kr is an inside air temperature gain, Kam is an outside air temperature gain, and Ks is solar radiation. Is a quantity gain, and C is a correction constant.

The required blowing temperature TAO thus obtained
Servo motor 161 that drives A / M door 16 based on
The opening degree of the A / M door 16 is set, and the mixing ratio between the air cooled by the evaporator 12 and the air heated by the heater 15 is controlled to adjust the temperature of the blown air. Like that.

A refrigerant compressor 20, which is directly driven by an engine mounted on a vehicle, has a variable capacity mechanism.
The discharge capacity is variably controlled by 201, and the solenoid valve that constitutes the capacity variable mechanism 201 is controlled by a control current from the control device 23.

Here, the relationship between the displacement of the compressor 20 and the control current supplied to the displacement varying mechanism 201 is, for example, as shown in FIG. That is, as the control current decreases, the capacity of the compressor 20 increases, and the refrigerant flow rate increases.

In the control unit 23, based on the target temperature information TEO set manually by the target temperature setting device 29 after the heat exchanger and the temperature information TE measured by the temperature sensor 28 after the heat exchanger, the PID is determined. The control current supplied to the variable displacement mechanism 201 of the compressor 20 is calculated by the control formula. Then, the flow rate of the refrigerant is variably controlled so that the temperature TE measured by the temperature sensor 28 is maintained at a value close to the set target temperature TEO.

In such an air conditioner, feedback control is performed so that the air temperature TE behind the evaporator approaches the set target temperature TEO.
At 23, the control current In for controlling the variable capacity mechanism 201 is controlled by PID (PI) based on the following equation.

[0022]

(Equation 1)

Where TE is the air temperature after the heat exchanger (evaporator), TEO is the target temperature after the heat exchanger, I is the control current, Kp is the proportional gain, Ti is the integration time, and θ is the sampling interval. . And n is now, n-1 is 1
The previous sampling state is shown.

In such PID control, when the proportional gain Kp is large, the response speed when changing the capacity of the compressor 20 is increased as shown in FIG. 3, and conversely, when the proportional gain Kp is small, the response speed is increased. The response speed becomes slow, and the temperature TE behind the evaporator 12 is easily stabilized.

The air conditioner according to this embodiment utilizes such a characteristic. As shown in FIG. 4, when the opening degree of the A / M door 16 has no margin near "Max Cool", the compressor is not used.
The proportional constant Kp of the PID control formula is set so that the response of the variable capacity control of 20 becomes faster, and the opening temperature of the A / M door 16 has a margin and the outlet temperature is sufficiently adjusted by the A / M door 16. When possible, the proportional constant Kp of the PID control formula is set so that the temperature behind the evaporator 12 is stabilized.

FIG. 5 shows a control flow of the control device 23 for performing such control. First, in step 101, detection signals from the respective sensors are read. And step 102
In step (1), the required blowing temperature TAO is calculated according to equation (1). After the required outlet temperature TAO has been calculated in this way, in step 103, A corresponding to the required outlet temperature TAO
/ The target opening SW of the M door 16 is calculated by the following equation (3),
Output in step 104. In step 104, an output is sent to the actuator that drives the A / M door 16 so that the target opening SW and the actual opening SP of the A / M door 16 match.

[0027]

(Equation 2)

In this equation, SW is the target opening of the A / M door 16, TA
O is the required outlet temperature and TW is the cooling water temperature.

In step 105, the opening degree SP of the A / M door 16 is determined.
Is compared with the set value Co to determine whether or not the opening of the A / M door 16 has a margin. If the opening SW is smaller than the set value Co and there is no margin in the opening, the process proceeds to step 106. In this step 106, the proportional constant Kp is set to the first set value C1, and "Kp = C1"
Set the response speed of D control faster.

In step 105, the opening degree SP is set to the set value Co.
When it is determined that the value is larger than the predetermined value, the process proceeds to step 107, where the proportional constant Kp of the PID control formula is set to a second set value C2 smaller than the first set value C1, and the response speed of the PID control is set to be slow. .

If the proportional constant Kp is set to C1 or C2 in steps 106 and 107, respectively, the variable capacity mechanism 201 of the compressor 20 is applied to the variable capacity mechanism 201 of the compressor 20 in steps 108 and 109 based on the proportional constant Kp based on the proportional constant Kp. The control current In to be supplied is calculated, and steps 110 and
At 111, the control current In is output to set the discharge capacity of the refrigerant compressor 20.

In the embodiments described above, the air temperature TE downstream of the evaporator 12 is controlled. However, this may be performed by controlling the refrigerant low pressure of the evaporator 12. In addition, control combining these can also be executed.

When such a low pressure refrigerant is used,
A pressure sensor is used in place of the temperature sensor 28, and the pressure sensor detects the refrigerant pressure of the evaporator 12.
Then, the control reference value is changed from temperature to pressure, or a value obtained by combining temperature and pressure.

Further, in the embodiment, the target temperature TEO is set in the target temperature setting device 29 behind the evaporator 12 by, for example, a variable resistor. The control may be performed in association with the required blowing temperature TAO obtained from sensors related to the air conditioner such as an inside air temperature sensor and a solar radiation sensor.

[0035]

As described above, according to the air conditioner for a vehicle according to the present invention, the proportional and integral control equations for obtaining the control current for controlling the capacity of the refrigerant compressor in accordance with the situation of the A / M door. A proportional constant is selected, and an appropriate response speed corresponding to the opening of the A / M door is set. Therefore, when there is no margin in the opening of the A / M door, the capacity of the refrigerant compressor is particularly controlled with good responsiveness, and the blowout temperature is smoothly controlled.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a vehicle air conditioner according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a capacity control current of a refrigerant compressor used in the embodiment and a refrigerant capacity.

FIG. 3 is a view for explaining responsiveness corresponding to a proportionality constant Kp of a PID control equation.

FIG. 4 is a diagram for explaining the relationship between the opening of the A / M door and the proportionality constant Kp.

FIG. 5 is a flowchart illustrating a control flow in the control device according to the embodiment.

[Explanation of symbols]

11 ... air passage, 12 ... evaporator, 13 ... blower, 15 ... heater, 16 ... air mix (A / M) door, 20 ... refrigerant compressor, 201 ... variable capacity mechanism, 23 ... control device.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuichi Kajino 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Inside Denso Co., Ltd. (56) References JP-A-4-257715 (JP, A) (58) Investigated Field (Int.Cl. ⁷ , DB name) B60H 1/00 101 B60H 1/32 624

Claims (1)

(57) [Claims] 1. A variable displacement refrigerant compressor whose discharge amount is variably controlled, a heat exchanger in which refrigerant compressed by the refrigerant compressor is circulated, and an output-side air temperature of the heat exchanger is detected. A post-heat-exchange temperature detection unit, a heating unit that is set in an air passage to which output air from the heat exchanger is supplied, and heats the output air from the heat exchanger, and the heating unit that is set in the air passage. An air mixing door for controlling the ratio of the amount of air passing through the air and the amount of air not passing through the heating means; and a heat exchanger detected by the target temperature after the heat exchanger and the temperature after the heat exchanger. Control means for calculating the discharge capacity of the variable displacement refrigerant compressor based on the proportional and integral control formulas based on the rear temperature and the proportional constant of the proportional and integral control formulas is an opening degree of the air mix door. Set corresponding to An air conditioner for a vehicle, wherein the air conditioner is used.