JP2936789B2 - 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 a vehicle air conditioner having improved compressor control means, particularly when a target temperature is set to increase.

[0002]

2. Description of the Related Art For example, in an air conditioner mounted on a vehicle, P (proportional) I (integral) D has conventionally been used as temperature control means for controlling the air temperature in the passenger compartment to a set target temperature.
It is well known to perform (differential) control. Further, the discharge capacity of the refrigerant compressor constituting the air conditioner for cooling the air discharged into the passenger compartment is controlled by an electric current. Is controlled based on the PID control.

In general, the proportional gain, integration time, and differentiation time of PID control are determined by a limit sensitivity method or the like, and are determined so as to achieve both stability and steady-state deviation.

However, in an air-conditioning system that performs a cooling operation, it is often difficult to achieve both the transient and steady-state stability such as the cool-down characteristic, etc., only by setting such constants. For example, if a constant is set so that the responsiveness when controlling by reducing the target temperature of the air temperature blown out from the heat exchanger from a certain temperature becomes faster, conversely, the target temperature of the blown air temperature is raised and controlled. In this case, after the blown air temperature exceeds the target temperature, the target temperature is stabilized while largely hunting. The overshoot exceeding the target temperature affects the blowout temperature, and gives an uncomfortable feeling to the occupant in the passenger compartment.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and in particular, when the target temperature is greatly increased, the temperature of the air blown into the vehicle compartment greatly overshoots. It is an object of the present invention to provide a vehicle air conditioner in which the capacity of a refrigerant compressor is controlled so as to be directed to a target value, and temperature control is performed without causing discomfort to passengers in a vehicle.

[0006]

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 the capacity control is performed by controlling the air flow from the outlet of the heat exchanger. This is executed by the PID control based on the temperature information of the actual air temperature corresponding to the temperature and the set target temperature information. In particular, when the target temperature is increased significantly, the temperature increase is divided into a plurality, The divided rise is set as a provisional target temperature.

[0007]

In a vehicle air conditioner, the mixing ratio of the cooled air from the heat exchanger supplied with the refrigerant and the heating air passing through the heater core supplied with the engine cooling water is determined by an air mixing door. To control the temperature of the air blown into the passenger compartment. Then, the cooling capacity is set according to the discharge capacity of the refrigerant compressor that discharges the refrigerant supplied to the heat exchanger. in this case,
When the target temperature is raised, the discharge capacity of the refrigerant compressor is controlled to decrease so as to reduce the cooling capacity of the heat exchanger, but the capacity of the refrigerant compressor is adjusted in accordance with the deviation from the target temperature. Is controlled, overshoot occurs. However, if the temperature deviation is divided into a plurality of parts and the target temperature is switched and controlled stepwise, the overshoot is suppressed in each step,
Temperature control that does not cause discomfort to the occupant is smoothly performed.

[0008]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of an air conditioner mounted on a vehicle. An engine 11 mounted on the vehicle directly drives a refrigerant compressor 12 via a belt. The refrigerant compressor 12 is of a variable displacement type whose compression discharge capacity is variably controlled, and includes a capacity variable mechanism by an electromagnetic valve 121.

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 set by the current supplied to the solenoid valve 121. Is done.

The compression discharge capacity of the refrigerant compressor 12 and the solenoid valve
The relationship with the current supplied to the solenoid valve 121 is set linearly with respect to the amount of current as shown in FIG. 2. As the control current supplied to the solenoid valve 121 decreases, the capacity of the compressor 12 decreases. And the flow rate of the discharged refrigerant increases with an increase in the capacity of the compressor 12.

The refrigerant discharged from the refrigerant compressor 12 having such a variable capacity is sent to an expansion valve 15 via a condenser 13 and a receiver 14. The refrigerant which has been expanded to a low temperature by the expansion valve 15 is: The heat is supplied to the evaporator 16 constituting the heat exchanger. Then, the output refrigerant from the evaporator 16 is returned to the compressor 12.

The evaporator 16 is set in the air passage 17, and the air flow generated by the fan 18 passes through the evaporator 16 and is cooled. A heater core 19 is set on the downstream side of the evaporator 16 in the air passage 17 so as to close almost half of the passage 17. Although not shown in detail, cooling water of the engine 11 is circulated through the heater core 19, and heats the passing air with the high-temperature cooling water.

An air mixing door which selectively closes an air introduction portion of the heater core 19 and an air passage portion excluding the heater core 19 is provided at the portion of the heater core 19.
20 are provided. The mixing ratio of the heating air that has passed through the heater core 19 by the air mixing door 20 and 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. .

At the air outlet from the evaporator 16,
The temperature sensor 21 is set. The temperature sensor 21 measures the outlet temperature Te of the evaporator 16, and the measured temperature information Te is supplied to a control circuit 22 constituted by a microcomputer or the like. The control circuit 22 is supplied with temperature setting information Ts from a temperature setting device 23 which is constituted by, for example, a variable resistance circuit and is manually set.

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

In the air conditioner configured as described above,
For example, feedback control is performed so that the air temperature on the outlet side of the evaporator 16 approaches the target temperature set by the temperature setting unit 23, and control is performed so that the temperature of air blown into the vehicle interior is set to an appropriate target temperature. Is done.

Here, in the control circuit 22, the PID control is executed by the following equation for calculating the current for controlling the solenoid valve 121 of the variable capacity refrigerant compressor 12. En = Ten−Teon In = In−1−Kp ｛(En−En−1) + (θ / Ti) × En｝ (1) where Te is the air temperature after the evaporator 16, and Teo is the evaporator 16 The subsequent target air temperature, 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 value immediately before.

In the expression (1) expressed in this way, in the state where the proportional gain Kp is large, when the target temperature Teo is changed from a small state to a large value as shown in FIG. Then head for stability.

Such overshoot of the air temperature after the evaporator 16 cannot be absorbed by the air mix door 20 even if corrected by the air mix door 20. Conversely, the air temperature behind the evaporator 16 rises. And opening the air mix door 20 has a synergistic effect with each other. Therefore, for example, an overshoot of 2.5 ° C. is expanded to 4 to 6 ° C. in the vehicle interior blowing temperature. When the proportional gain Kp is reduced, overshoot does not occur as shown in FIG. However, it takes a lot of time to reach the target value.

Therefore, in the air conditioner according to this embodiment, when a constant with a fast response is set and the target temperature Teo is set to rise, the temperature rise width is divided into a plurality of stages as shown in FIG. , So that the target temperature is gradually increased. That is, by performing the temperature change slowly, the overshooting control of the air temperature after the evaporator 16 is eliminated. Then, the occurrence of overshoot of the vehicle interior outlet temperature is prevented.

By setting the target temperature rising state in a stepwise manner as described above, it is possible to improve the feeling when the target temperature and Teo are raised by the PID control formula and to shorten the response time when the target temperature Teo is lowered. realizable.

FIG. 5 shows a control flow in the control circuit 22 for executing such a stepwise temperature rise control.
First, in step 101 after the start, it is determined whether or not the target air temperature Teo after the evaporator 16 has been changed.
If it is determined that eo has been changed, the process proceeds to step 102.

At 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 routine proceeds to step 103, where the target temperature Teo is increased.
The difference ΔTeo between eo and the air temperature Te after the actual evaporator
Ask for. Then, at step 104, the temperature rise width ΔT
It is determined whether or not eo is a value exceeding the specified temperature difference Co.

When it is determined that the target temperature Teo has risen by Co or less than the actual air temperature Te after the evaporator 16, when it is determined in step 101 that the target temperature Teo has not been changed, and If it is determined in step 102 that the target temperature has been changed but is not a change in the upward direction, the process proceeds to step 105 and the normal PID
Control is performed.

If it is determined in step 104 that ΔTeo exceeds Co, the flow advances to step 106 to set the counter I, and then to step 107. In this step 107, the air temperature Te at the time of change is stored in the control circuit 22 as Tee, ΔTeo is divided, and the one-step temperature step is defined as See.
tp.

This Stp is stored in advance in a storage device constituting the control circuit 22. For example, when the target temperature Teo is changed from 3 ° C. to 10 ° C., it is divided into three stages. The target temperature of each stage is C1 = 3 ° C., C2 =
Program as follows: 5 ° C, C3 = 7 ° C. In the counter I, the target temperature is selected by the counting. In the initial state, "I = 1" is set, and
1 = Select 3 ° C.

In step 108, the provisional target temperature Teo 'is set by adding the temperature step Stp corresponding to C1 selected in step 107 to the air temperature Tee at the time of the first change. Then, the provisional 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 Teo '
Then, it is determined whether or not a predetermined time interval TM for changing the time has elapsed. If the time TM has been exceeded, the routine proceeds to step 111, where the provisional target temperature Teo 'and the target temperature Teo are compared.

If it is determined in step 110 that the time TM has not elapsed, the process returns to step 109. Step 11
If the temporary target temperature Teo 'has not reached the target temperature Teo in step 1, the routine proceeds to step 112, where the counter I is incremented by "+1".
Then, the routine 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,
This process is repeated until the temporary target temperature Teo 'reaches the target temperature Teo.

That is, when the difference between the current temperature and the target temperature is large as described above, a temporary target temperature is set by dividing the temperature difference into a plurality of stages, and compression is performed toward the temporary target temperature. The compression capacity of the machine 12 is controlled. Therefore, the output air temperature of the air conditioner is controlled to increase without overshooting, hunting, or the like.

In the embodiment, the air temperature Te downstream of the evaporator 16 is controlled. However, this can also achieve the same purpose by controlling the refrigerant low-pressure output of the evaporator 16, and may be controlled by combining these.

When the control based on the refrigerant low pressure output of the evaporator 16 is performed, 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 obtained by combining temperature and pressure.

Further, in the embodiment, the target temperature is set to the temperature setter 23.
Then, it was set by a variable resistor. But,
This is an outdoor air temperature sensor,
The control and setting may include sensors related to the air conditioner such as an inside air temperature sensor and a solar radiation sensor.

[Brief description of the drawings]

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

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

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

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

FIG. 5 is a flowchart for explaining the flow of the operation of the embodiment.

[Explanation of symbols]

11 ... engine, 12 ... refrigerant compressor, 121 ... solenoid valve (for capacity control), 16 ... evaporator (heat exchanger), 17 ... air passage, 18 ... fan, 19 ... heater core, 20 ... air mix door, 21 ... Temperature sensor, 22 control circuits.

────────────────────────────────────────────────── ─── 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-2-290714 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) B60H 1 / 00,1 / 32 F24F 11/02 102

Claims (1)

(57) [Claims] 1. A capacity control means for variably controlling a discharge capacity of a refrigerant compressor, a heat exchange means for circulating and supplying a refrigerant discharged from the refrigerant compressor, and a heat exchanged air from the heat exchange means. Actual temperature measuring means for measuring actual temperature information corresponding to the temperature, and control means for controlling the capacity control means based on a difference between the actual temperature information detected by the means and the set target temperature information. The control means includes means for determining that a temperature difference between the actual temperature information and the target temperature information is equal to or more than a specified value in a state where the target temperature is increased. Means for dividing the temperature difference into a plurality of pieces based on the set conditions, and a provisional target temperature for increasing the temperature based on each of the divided temperature differences. Set this temporary target temperature A vehicle air conditioner, 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 stepwise up to a set target temperature.