JPH04345520A - Air conditioning device for vehicle - Google Patents

Abstract

PURPOSE:To provide an automotive air conditioning device capable of control without any uncomfortable overshoot to persons on board a vehicle particularly in the case of control for a sudden rise in temperature. CONSTITUTION:A delivery coolant from a variable displacement cooling compressor 12 driven by an engine 11 is supplied to an evaporator 16 via a condenser 13, a receiver 14 and an expansion valve 15. Signals for output air temperature Te detected by a temperature sensor 21 and target temperature Teo set by a temperature setting unit 23 are supplied to a control circuit 22, and this circuit 22 controls the capacity of the compressor 12. When the target temperature Teo is set at level higher than the actual temperature Te, the width of the set temperature is divided into a plurality of steps in the circuit 22, and temperature Teo' temporary for each step is set. Then, the delivery capacity of the compressor 12 is controlled for a temperature rise in step toward the temporary temperature Teo'.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle air conditioner with improved compressor control means, particularly when a target temperature is set to rise.

0002

2. Description of the Related Art For example, in an air conditioner installed in a vehicle, temperature control means for controlling the interior air temperature to a set target temperature has conventionally been used as P (proportional) I (integral) D (
It is well known that differential) control is performed. In addition, the discharge capacity of the refrigerant compressor that constitutes the air conditioner for cooling the air discharged into the vehicle interior is controlled by electric current. The control of the current value is calculated based on this PID control.

Generally, the proportional gain, integral time, and differential time of PID control are determined by a limit sensitivity method, etc., and are determined so as to achieve both stability and steady-state deviation.

[0004] However, in an air conditioner that performs a cooling operation, it is often difficult to achieve both stability in transient and steady states, especially in cool-down characteristics, by simply setting such constants. For example, if you set a constant so that the response is faster when controlling the target temperature of the air blowing from a heat exchanger by lowering it from a certain temperature, conversely, you can control the target temperature of the blowing air by increasing it. In this case, after the temperature of the blown air exceeds the target temperature, it stabilizes at the target temperature while largely hunting. This overshoot exceeding the target temperature affects the air outlet temperature and causes discomfort to the occupants inside the vehicle.

[0005]

[Problems to be Solved by the Invention] The present invention was made in view of the above points, and particularly when the target temperature is significantly increased, the temperature of the air blown into the vehicle interior may greatly overshoot. An object of the present invention is to provide a vehicle air conditioner in which the capacity of a refrigerant compressor is controlled so as to move toward a target value without causing any discomfort, and temperature control is executed without causing discomfort to occupants in a vehicle interior.

[0006]

[Means for Solving the Problems] In the vehicle air conditioner according to the present invention, the discharge capacity of the refrigerant compressor is controlled based on an external command, and this capacity control is performed by controlling the discharge capacity of the refrigerant compressor from the outlet of the heat exchanger. It is executed by PID control based on the temperature information of the actual air temperature corresponding to the temperature and the set target temperature information, and when the target temperature is increased particularly large, the temperature increase is divided into multiple parts, The divided increases are set as temporary target temperatures.

[0007]

[Operation] In a vehicle air conditioner, the air mix door controls the mixing ratio of the cooled air from the heat exchanger to which refrigerant is supplied and the heating air that passes through the heater core to which engine cooling water is supplied. to control the temperature of the air blown into the vehicle interior. The cooling capacity is then set in accordance with the discharge capacity of the refrigerant compressor that discharges the refrigerant supplied to the heat exchanger. in this case,
When the target temperature is increased, the discharge capacity of the refrigerant compressor is controlled to decrease so as to reduce the cooling capacity in the heat exchanger, but the capacity of the refrigerant compressor is increased in response to the deviation from the target temperature. If it is controlled, overshoot will occur. However, if this temperature deviation is divided into multiple parts and the target temperature is switched and controlled in stages,
At each stage, overshoot is suppressed, and temperature control can be smoothly performed without causing discomfort to the occupants.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an air conditioner mounted on a vehicle, and a refrigerant compressor 12 is directly driven by an engine 11 mounted on the vehicle via a belt. The refrigerant compressor 12 is of a variable capacity type in which the compression and discharge capacity is variably controlled, and includes a variable capacity mechanism using a solenoid valve 121.

[0009] Here, the solenoid valve 121 constituting the variable capacity mechanism of the refrigerant compressor 12 is driven by the amount of current supplied, and the compressor capacity is determined by the solenoid valve 121.
set by the current supplied to the

The relationship between the compression discharge capacity of the refrigerant compressor 12 and the current supplied to the solenoid valve 121 is set linearly with respect to the amount of current as shown in FIG. As the supplied control current becomes smaller, the capacity of the compressor 12 becomes larger, and as the capacity of the compressor 12 increases, the flow rate of refrigerant discharged increases.

The refrigerant discharged from the variable capacity refrigerant compressor 12 is sent to the expansion valve 15 via the condenser 13 and receiver 14, and the refrigerant expanded at the expansion valve 15 to a low temperature is It is supplied to an evaporator 16 that constitutes a heat exchanger. The output refrigerant from the evaporator 16 is then returned to the compressor 12.

[0012] The evaporator 16 is set within the air passage 17, and the air flow generated by the fan 18 passes through the evaporator 16 and is cooled. Air passage 17
A heater core 19 is set downstream of the evaporator 16 so as to close approximately half of the passage 17. Cooling water for the engine 11 is circulated through the heater core 19 (not shown in detail), and the high-temperature cooling water heats the air passing through it.

[0013] In this heater core 19 part,
An air mix door 20 is provided that selectively closes the air introduction portion of the heater core 19 and the air passage portion excluding the heater core 19 portion. The heated air passed through the heater core 19 by the air mix door 20,
The mixing ratio with the cooling air from the evaporator 16 that does not pass through the heater core 19 is variably controlled to control the temperature of the air blown into the vehicle interior.

A temperature sensor 21 is installed at the air outlet from the evaporator 16. This temperature sensor 2
1 measures the outlet temperature Te of the evaporator 16, and this measured temperature information Te is supplied to a control circuit 22 constituted by a microcomputer or the like. This control circuit 22 includes a temperature setting device 2 which is configured by, for example, a variable resistance circuit and which is manually operated and set.
Temperature setting information Ts from 3 is supplied.

The control circuit 22 calculates a control current using a PID control formula based on the input information Te and Ts, and controls the supply of a control current corresponding to the calculation result to the solenoid valve 121 of the refrigerant compressor 12. That is, the temperature Te measured by the temperature sensor 21 is the set target temperature T.
The discharge capacity of the refrigerant compressor 12 is variably controlled so that it is maintained at a value close to s.

[0016] In the air conditioner configured in this way,
For example, the air temperature on the outlet side of the evaporator 16 is feedback-controlled so as to approach the target temperature set by the temperature setting section 23, and the temperature of the air blown into the passenger compartment is controlled to be set to the appropriate target temperature. be done.

Here, the control circuit 22 executes PID control using the following equation for calculating the current that controls the electromagnetic valve 121 of the variable capacity refrigerant compressor 12. En = Ten-Teon
In = In-1 - Kp {( En - En-1)
+(θ/Ti)×En}……(1) However, Te is the air temperature after the evaporator 16, T
eo is the target air temperature after the evaporator 16, I is the control current, Kp is the proportional gain, Ti is the integration time, θ is the sampling interval, n indicates the current value, and n-
1 indicates the previous value.

In equation (1) expressed in this way, when the proportional gain Kp is large, overshoot occurs when the target temperature Teo is changed from a small state to a large value as shown in (A) of FIG. After that, things stabilize.

Such an overshoot in the air temperature after the evaporator 16 cannot be completely absorbed even if it is substantially corrected by the air mix door 20, and on the contrary, the air temperature behind the evaporator 16 increases. This and opening the air mix door 20 have a synergistic effect. Therefore, for example, an overshoot of 2.5° C. is increased to 4 to 6° C. in the vehicle interior air blowing temperature. Also, if the proportional gain Kp is decreased, (B
), no overshoot occurs. but,
It takes a lot of time to reach the target value.

Therefore, in the air conditioner according to this embodiment, a fast response constant is set, and the target temperature Teo
When setting the target temperature to increase, the temperature increase width is divided into a plurality of steps as shown in FIG. 4, so that the target temperature is gradually increased. That is, by changing the temperature slowly, overshoot control of the air temperature after the evaporator 16 is eliminated. Then, the occurrence of an overshoot in the air outlet temperature inside the vehicle is prevented.

[0021] By setting the increase state of the target temperature in stages as described above, the target temperature according to the PID control formula and Teo
It is possible to achieve both an improved feeling when the target temperature Teo rises and a shortened response time when the target temperature Teo falls.

FIG. 5 shows the flow of control in the control circuit 22 that executes such stepwise temperature increase control. First, after starting, in step 101, the evaporator 1 is
It is determined whether or not there is a change in the target air temperature Teo after 6. If it is determined that there is a change in the target air temperature Teo, the process proceeds to step 102.

In step 102, it is determined whether or not the target temperature Teo is to be increased. If it is determined that the target temperature is to be increased, the process proceeds to step 103 to compare the target temperature Teo with the actual temperature after the evaporator. Air temperature Te
Find the difference ΔTeo. And step 104
Then, it is determined whether this temperature increase width ΔTeo is a value exceeding the specified temperature difference Co.

[0024] Then, when it is determined that the target temperature Teo has increased by Co or less than the actual air temperature Te after the evaporator 16, and when it is further determined that there is no change in the target temperature Teo in step 101, and If it is determined in step 102 that even if there is a change in the target temperature, it is not a change in the upward direction, step 105
Then proceed to perform normal PID control.

If it is determined in step 104 that ΔTeo exceeds Co, the process proceeds to step 106, where the counter I is set, and then the process proceeds to step 107. In this step 107, the air temperature Te at the time of change is stored as Te in the control circuit 22, and ΔTeo is divided and one temperature step is set as Stp.

This Stp is stored in advance in the storage device constituting the control circuit 22. For example, when changing the target temperature Teo from 3°C to 10°C, it is divided into three stages. The target temperature for each stage is C1 = 3℃
, C2 = 5°C, C3 = 7°C. Then, the counter I selects the target temperature based on the count, and in the initial state, it is set to "I=1" and C1=3° C. is selected.

In step 108, C1 selected in step 107 is used as the air temperature Tee at the time of the first change.
The temporary target temperature Teo' is set by adding the temperature step Stp corresponding to . Then, this temporary target temperature Teo'
is output in step 109, and the control current of the refrigerant compressor 12 is changed and controlled by PID control.

In step 110, one temporary target temperature T
It is determined whether or not a predetermined time interval TM for changing eo' has elapsed, and when the time TM has been exceeded, the process proceeds to step 111 to compare the tentative target temperature Teo' up to that point with the target temperature Teo. .

If it is determined in step 110 that the time TM has not elapsed, the process returns to step 109. Further, in step 111, the temporary target temperature Teo' is changed to the target temperature Te.
If the temperature has not reached o, the process proceeds to step 112, where the counter I is incremented by 1, and the process proceeds to step 106, where the next provisional target temperature (C2) is set. Then, a process of sequentially adding the changed temperature range is performed, and this process is repeated until the tentative target temperature Teo' reaches the target temperature Teo.

In other words, when the difference between the current temperature and the target temperature is large like this, a temporary target temperature is set by dividing the temperature difference into multiple stages, and compression is performed toward this temporary target temperature. The compression capacity of the machine 12 is controlled. Therefore, the output air temperature of this air conditioner is controlled to increase without overshooting, hunting, etc. occurring.

In the embodiment, it has been explained that the air temperature Te on the downstream side of the evaporator 16 is controlled. However, this objective can be similarly achieved by controlling the refrigerant low-pressure output of the evaporator 16, and these may also be controlled in combination.

When performing control based on the low-pressure refrigerant output of the evaporator 16, a pressure sensor is used instead of the temperature sensor 21 to detect the refrigerant pressure on the output side of the evaporator 16. Then, the target value is changed from temperature to pressure, or to a value that is a combination of temperature and pressure.

Furthermore, in the embodiment, the target temperature is set by the temperature setting device 2.
3, it was set using a variable resistor. However, this may be combined with an automatic air conditioner and controlled and set by including sensors related to the air conditioner such as an outside air temperature sensor, an inside air temperature sensor, and a solar radiation sensor.

[Brief explanation of the drawing]

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

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

FIG. 3 is a diagram illustrating the relationship between proportional gain and control mode of PID control.

FIG. 4 is a diagram illustrating a setting state of a temporary target temperature in the above embodiment.

FIG. 5 is a flowchart illustrating the operation flow of the above embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11... Engine, 12... Refrigerant compressor, 121... Solenoid valve (for capacity control), 16... Evaporator (heat exchanger), 1
7...Air passage, 18...Fan, 19...Heater core, 20
...air mix door, 21...temperature sensor, 22 control circuit.

Claims (1)

[Claims] 1. Capacity control means for variably controlling the discharge capacity of a refrigerant compressor, heat exchange means to which refrigerant discharged from the refrigerant compressor is circulated and supplied, and air with which heat has been exchanged from the heat exchange means. an actual temperature measuring means for measuring actual temperature information corresponding to the temperature; and a control means for controlling the capacity controlling means based on the difference between the actual temperature information detected by this means and the set target temperature information. The control means comprises:
means for determining that the temperature difference between the actual temperature information and the target temperature information is greater than or equal to a specified value in a state where the target temperature is increased; In the determined state, means for dividing the temperature difference into a plurality of parts based on a set condition, and setting a provisional target temperature for temperature increase based on each of the divided temperature differences, An air conditioner for a vehicle, comprising means for calculating a control amount of the capacity control means in response to the above, and controlling the discharge capacity of the refrigerant compressor in stages up to a set target temperature.