JP3060554B2 - 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 using a variable displacement compressor whose displacement is variably controlled based on an external command.

[0002]

2. Description of the Related Art An air conditioner mounted on a vehicle uses a compressor for compressing a refrigerant whose compression capacity is variably controlled by an external command. Particularly, in a vehicle air conditioner, the compressor is directly driven by an engine mounted on the vehicle, and has a property that the rotation speed of the compressor changes in accordance with the rotation speed of the engine. Therefore, a compressor whose compression capacity is variably controlled is effectively used.

[0003] Refrigerant compressed by such a compressor is supplied to an expansion valve via a condenser, and the refrigerant which has been expanded and cooled to a low temperature by the expansion valve is supplied to an evaporator, and the evaporator exchanges heat with air. Is performed. The capacity of the compressor is adjusted so that the outlet temperature TE on the downstream side of the evaporator matches the target evaporator outlet temperature TEO obtained based on the vehicle interior temperature, the outside air temperature, the solar radiation condition, and the target vehicle interior temperature. To control.

In such compressor capacity control, feedback control is performed by, for example, PI control. In order to improve the control stability, it is preferable that the feedback gain be small. However, if the feedback gain is reduced, the control response becomes worse,
For example, it is difficult to control the rapid cooling of the vehicle interior. Also, increasing the feedback gain improves the responsiveness,
As shown in FIG. 6, the overshoot increases with respect to the target, resulting in poor control stability.

[0005] In particular, in a system using such a variable displacement compressor, when power saving is to be achieved, the load is low and cold air is not particularly required.
It has been considered to perform economy control in which the capacity of the compressor is controlled to be small to increase the outlet temperature on the downstream side of the evaporator and the amount of reheat is reduced. In such control, the reheat amount is set to “0” as much as possible to further increase the power saving effect. Specifically, it is assumed that “grill outlet temperature = evaporator (evaporator) outlet temperature”. When such control is performed, the over-shoot causes the after-evaporator outlet actual temperature TE to become higher than its target temperature TEO. In addition, the air temperature inside the vehicle cannot be adjusted by the air mix door. That is, high-temperature air is blown into the passenger compartment from the grill outlet to give an occupant an uncomfortable feeling.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points. In particular, in a system using a compressor that varies the refrigerant compression capacity in response to an external command, for example, the reheat amount is set to "0". When performing a power-saving operation of a compressor such as that described above, for example, high-temperature air is blown from the grill outlet, and the occurrence of a situation that may cause discomfort to the occupant is effectively prevented, and the power-saving effect is maximized. It is an object of the present invention to provide an air conditioner for a vehicle that is used in a vehicle.

[0007]

In a vehicle air conditioner according to the present invention, refrigerant is compressed using a compressor whose refrigerant compression capacity is variably controlled by an external command, and is circulated to an evaporator. The compressor performs feedback control of the compressor by comparing the downstream side outlet temperature TE of the evaporator with its target outlet temperature TEO, and “TE> TE”
The feedback gain is set to be larger when "O" than when "TE <TEO".

[0008]

In the vehicle air conditioner thus configured,
For example, if the actual temperature TE after the evaporator becomes higher than the target temperature TEO when the reheat amount is “0”, the grill air temperature cannot be further reduced by the air mixing door, and the grill air temperature becomes lower than the target temperature. However, in such a state, the feedback gain of the capacity control of the compressor is controlled to be high, and the response of the compressor is improved.
The actual outlet temperature TE after the evaporator is reduced. On the other hand, when “TE <TEO”, since the grill outlet temperature can be controlled by the air mix door, quick response of the compressor is not required, and if the compressor gain is controlled with a small feedback gain, Good and effective power saving control is enabled.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration, in which an evaporator 11 is set inside a duct 12 for circulating conditioned air so as to close this air passage. A blower 13 is provided on the upstream side of the evaporator 11 of the duct 12, and the outside air or vehicle interior air selected by the inside / outside air switching door 14 is introduced and sent to the evaporator 11.

The evaporator 11 circulates refrigerant discharged from a variable capacity compressor 15 in which the compression capacity of the refrigerant is varied. The refrigerant is compressed by the compressor 15, cooled by the condenser 16, and passed through the receiver 17. The refrigerant that is supplied to the expansion valve 18 is cooled by the expansion valve 18 and cooled to a low temperature.
It is to be circulated to 11. That is, the air sent to the downstream side after passing through the evaporator 11 is cooled according to the compression capacity of the compressor 15.

A heater core 19 is provided downstream of the evaporator 11 of the duct 12 so as to partially block an air passage formed by the duct 12. Although not shown in detail, the engine coolant is circulated through the heater core 19, and the air passing through the heater core 19 is heated by heat exchange with the coolant heated by the engine.

An air mix door (A / M) 20 is provided at a portion corresponding to the heater core 19. The air mix door 20 is variably controlled from a state in which the air inlet portion of the heater core 19 is closed to a state in which an air passage other than the heater core 19 is closed, and is heated by the air cooled by the evaporator 11 and the heater core 19. Air outlet formed on the downstream side of the duct 12 by controlling the mixing ratio with the air
Send to 211 and 212.

That is, the temperature of the air blown from the outlets 211 and 212 is basically controlled by the air mix door 20. This outlet 211 and 212
Is set as a grill outlet in the cabin,
For example, the upper and lower portions are set at different positions. The mode switching doors 221 and 221 for setting the blowing mode are provided in the outlets 211 and 212, respectively.
222 are provided.

In order to control such an air conditioning mechanism, a control circuit constituted by, for example, a microcomputer or the like is used.
23 are provided. The control circuit 23 includes set temperature information set by a temperature setting device, vehicle interior temperature information from a temperature sensor set in the vehicle interior, outside air temperature information from an outside air temperature sensor, solar radiation information from a solar radiation sensor, engine cooling. Cooling water temperature information from the water temperature sensor and evaporator
The post-evaporation temperature information from the temperature sensor set on the downstream side of 11 is converted into a digital signal by the A / D converter 24 and input.

The control circuit 23 controls the air-conditioning mechanism based on such input information. The blower driving circuit 251 to which a command is given from the control circuit 23 controls the blower 13 to control the air flow, The (Mg) drive circuit 252 controls a magnet mechanism that controls on / off of a power transmission mechanism (clutch) between the compressor 15 and the engine.

The control valve 26 for controlling the compression capacity of the compressor 15 is controlled by a control valve drive circuit 253 instructed by the control circuit 23. The air mix door 20 and the mode switching doors 211 and 212 are controlled by the control circuit 23, respectively. A / M drive circuit 254 and mode switching circuit 25
To be controlled by 5.

Here, the control valve 26 of the compressor 15
For example, by increasing the supplied current, the compression capacity of the compressor 15 is controlled to be small, and by decreasing the current supplied to the control valve 26, the compression capacity of the compressor 15 is controlled to be increased.

FIG. 2 shows the flow of air conditioning control in the control circuit 23, which is the same as a normal automatic air conditioner except for the control part of the compressor 15. That is, first, in step 101, detection information from each sensor is read, and based on the input information, a target vehicle interior temperature, specifically, a target temperature TAO of the grill outlet portion, is calculated in step 102. In step 103, the opening degree of the air mix door 20, the air volume of the blower 13, the blowing mode, and the inside / outside air selection mode of the introduced air are determined in step 103 in accordance with the target temperature TAO. Then, in step 104, the target outlet temperature TEO after the evaporator 11 is calculated based on the above determined information.

For example, according to the relationship shown in FIG. 3, the target outlet temperature TEO after the evaporator 11 is determined based on the target grill outlet temperature TAO. The characteristics shown in FIG. 3 are stored and set in a storage device of a microcomputer constituting the control circuit 23, for example. And this target temperature TEO
In step 105, the control current of the control valve 26 of the compressor 15 is determined.

The control in this step 105 is performed as shown in FIG. 4. First, in step 201, the target temperature TEO is subtracted from the blowout actual temperature TE after the evaporator 11, and the deviation En is obtained. Thereafter, in step 202, it is determined whether or not the obtained deviation En is greater than "0". If it is determined that the actual temperature TE is higher than the target temperature TEO and the deviation En is positive, the process proceeds to step 203. On the other hand, when it is determined that the deviation En is negative, step 204 is executed.
Proceed to. Then, in step 203, the PI control gain K
p is set to the basic gain G, and in step 204, the gain K
Set p to αG. Then, the determined gain K
According to p, in step 205, the control current In of the control valve 26 is calculated based on the PI control equation. Here, “0 <α <
In step 204, Kp is made smaller than the basic gain.

More specifically, when “TE> TEO” due to overshoot or the like, the gain is set large, so that the capacity of the compressor 15 is quickly increased,
The control current is controlled so that the blowing temperature TE after the evaporator 11 is reduced. In particular, in a region where the reheat amount is “0”, it is possible to prevent a situation in which high-temperature air is blown out of the grill and the passengers feel uncomfortable.

On the other hand, in the case of "TE <TEO", since the gain Kp is smaller than the basic gain G, the control stability is reliably improved. And in such a state, the deviation of “TEO−TE” is
It can be adjusted by 20 so that unpleasant temperature wind is not blown out of the grill.

Thereafter, at step 106 (FIG. 2), a command is output to the control valve 26 based on the determined information, the compression capacity of the compressor 15 is adjusted, and the actual blowout temperature TE after the evaporator 11 is adjusted. The target temperature TEO is controlled.

The economy control by the external control of the compression capacity of the compressor 15 for refrigerant compression is performed, and in the region where the reheat amount is "0" as shown in FIG. In a higher state, the temperature of the air blown into the vehicle compartment cannot be reduced below the actual temperature TE, regardless of the state of the air mix door 20 being controlled.

That is, since the temperature cannot be adjusted by the air mix door 20, it is necessary to control this by the compressor 15. For this reason, the gain Kp is set large in order to improve the response on the compressor 15 side.

On the other hand, in the case of "TE <TEO", since the grill blowing temperature can be adjusted by the air mix door 20, a quick response by the compressor 15 is not required, and the gain is increased to improve control stability. Make it smaller.

Here, "α" for setting the gain Kp is considered to be about "0.5" at present, but an appropriate value may be selected in a range of "0 <α <1". Can be selectively selected.

FIG. 5 shows another embodiment of the means for determining the compressor control current.
Is performed in the same manner as in the case of FIG. And step
If it is determined in step 102 that the deviation En is larger than "0", the routine proceeds to step 211, where the target value TA of the grill outlet temperature is set.
O and the outlet target temperature TEO after the evaporator 11 are compared, and when the condition of “TAO ≦ TEO” is satisfied, that is, when the condition of the reheat amount is “0”, the process proceeds to step 203,
Set the gain Kp to G. At other times, the routine proceeds to step 204, where the gain Kp is set to "αG".
That is, the gain is set to a large value when the reed amount is “0” so that uncomfortable control is not performed.

The control of the current for driving the control valve 26 of the compressor 15 is not limited to the PI control as in the embodiment, and any control method can be appropriately employed as long as it is a feedback control. The external variable displacement compressor 15 whose compression capacity is controlled can be arbitrarily selected as long as the compression capacity can be controlled by an external signal.

[0030]

As described above, according to the vehicle air conditioner according to the present invention, it is possible to ensure control stability in a state where power is saved, and, for example, to reduce the actual blowout temperature after the evaporator. When the temperature becomes higher than the target temperature, the compressor is controlled with good responsiveness, and it is possible to reliably avoid air-conditioning control that gives a passenger an uncomfortable feeling. Functions will be exhibited stably.

[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 flowchart showing a flow of an operation of the control circuit of the embodiment.

FIG. 3 is a diagram showing conditions for determining a post-evaporator blowing target temperature TEO.

FIG. 4 is a flowchart for explaining a control current determining step shown in FIG. 2 in more detail;

FIG. 5 is a flowchart illustrating another embodiment of a control current determining unit.

FIG. 6 is a view for explaining a conventional mode of controlling the post-evaporator outlet temperature.

[Explanation of symbols]

11 evaporator, 12 duct, 13 blower, 15 compressor (external variable displacement type), 19 heater core, 20 air mix door, 23 control open circuit.

Claims (1)

(57) [Claims] 1. A refrigerant compression compressor whose capacity is variably controlled based on an external control signal, and a refrigerant compressed by the compressor is circulated through a condenser and an expansion valve to cool air flowing through the duct. An evaporator, a heater core set in a passage of an airflow cooled by the evaporator, and a flow of air passing through the heater core, and a flow of air not passing through the heater core. And a means for feedback-controlling the capacity of the compressor based on a comparison result between the actual temperature TE on the downstream side of the evaporator and the target temperature TEO on the downstream side of the evaporator. When the relationship between the target temperature TEO and the target temperature TEO is "TE>TEO", the feedback gay The vehicle air conditioner is characterized in that the air conditioning is set to be large.