JP2853475B2 - 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 for instructing an increase in an engine idle speed during a compressor operation.

[Prior art]

[0002] A vehicle comprising a compressor for compressing a refrigerant driven by an engine, an evaporator for vaporizing the refrigerant compressed by the compressor, and a blower fan for blowing the introduced air through the evaporator into the vehicle interior. Air conditioners for air conditioners are known. In vehicles equipped with this type of air conditioner, for example, a valve (AAC valve) for adjusting an auxiliary air flow rate is provided in an air passage bypassing a throttle valve, and the AAC valve is used when the compressor is operated (ON). The engine idle speed is increased by opening the engine by a certain opening (for example, Nissan Service Bulletin June 1987, No. 578, No. B-7)
1 page).

[0003]

SUMMARY OF THE INVENTION In such a vehicle,
Even when the heat load is not so large, the engine idle speed is increased in conjunction with the turning on of the compressor. However, when the heat load is not so large, a sufficient cooling performance can often be obtained without increasing the engine idle speed and increasing the refrigerant flow rate. This leads to poor fuel economy.

Therefore, a sensor for detecting the air temperature immediately after the evaporator (hereinafter referred to as the temperature immediately after the evaporator) is provided, and the thermal load on the evaporator is estimated using the temperature immediately after the evaporator. It is conceivable to control the number. According to this, when the heat load on the evaporator is small, the idling speed does not increase even if the compressor is turned on, so that the fuel efficiency can be improved. By the way, the temperature immediately after the evaporation is originally used, for example, for controlling a fixed displacement compressor to be turned on and off near the freezing limit of the evaporator. However, when a variable displacement compressor is used, the required cooling capacity is required. Since the discharge amount of the refrigerant can be controlled in accordance with the temperature, there is almost no need to turn the compressor on and off, and the temperature sensor immediately after the evaporation is unnecessary. For this reason, in the method of controlling the engine idle speed based on the temperature immediately after the evaporation as described above, it is necessary to newly provide a temperature sensor immediately after the evaporation when adopting a system without the temperature sensor immediately after the evaporation, which leads to a cost reduction. There is a problem that leads to up.

It is an object of the present invention to provide an air conditioner for a vehicle that can perform appropriate idle speed control without deteriorating fuel efficiency without using a temperature sensor immediately after evaporation.

[0006]

Means for solving the problem will be described with reference to FIG.
The vehicle air conditioner according to the present invention includes a compressor 102 driven by an engine 101 to compress a refrigerant, an evaporator 103 for vaporizing the refrigerant compressed by the compressor 102, and an evaporator 103 for supplying air introduced from outside the vehicle. A variable-speed blower fan 104 for passing the air through the vehicle interior, an outside air temperature sensor 105 for detecting the outside air temperature, a judging means 106 for judging the speed of the blower fan 104, and a heater when the outside air temperature is higher than a reference value. A thermal load determining means 108 comprising a determining unit for determining that the load is equal to or higher than a predetermined value; a reference value setting unit for setting a reference value of the outside air temperature to be lower as the blower fan speed is higher; Is output as a first rotation speed, and when the compressor is operating, the heat load determination means 10 Speed command means 107 for outputting a command for setting the engine idle speed to a second speed higher than the first speed only when the heat load determined by the above is equal to or greater than a predetermined value, This solves the above problem. According to a second aspect of the present invention, when the compressor operates and the heat load determined based on the vehicle interior temperature and the target value of the vehicle interior temperature is equal to or greater than a predetermined value, the engine idle speed is increased to the second rotation speed. A command for outputting a third rotation speed higher than the number of rotations is output. According to a third aspect of the present invention, the compressor, the evaporator, the blower fan, the determining means, the first thermal load determining means for determining a thermal load based on the outside air temperature and the blower fan speed, In addition to the load determining means, a second thermal load determining means for determining a thermal load based on at least a vehicle interior temperature and a target value of the vehicle interior temperature, and an idle speed command based on the determination results of the two thermal load determining means. And a rotation speed command means for outputting the rotation speed. The control contents of the rotation speed command means are as follows. (A) When the compressor is not operating, a command signal for setting the engine idle speed to the first speed is output. (B) When the compressor is operating and the heat load determined by the second heat load determination means is less than a predetermined value, the heat load determined by the first heat load determination means is equal to or more than a predetermined value. The engine idle speed only at the first
And outputs a command to set the second rotation speed higher than the rotation speed. (C) When the compressor is operating and the thermal load determined by the second thermal load determining means is equal to or greater than a predetermined value, the engine idle speed is reduced to the first idle load regardless of the determination result of the first thermal load determining means. A command to output a third rotation speed higher than the second rotation speed is output.

[0007]

The heat load determining means determines the heat load on the evaporator 103 based on the logical product of the outside air temperature and the blower fan speed. When the compressor is not operating, the rotation speed command means 107 outputs a command signal for setting the engine idle rotation speed to the first rotation speed. When the compressor is operating, the heat load determined by the heat load determination means 108 is a predetermined value. Only in the above case, a command for setting the engine idle speed to the second speed higher than the first speed is output. (2) The invention according to claim 3 The rotation speed command means, when the compressor is operating and the heat load judged by the second heat load judgment means is equal to or more than a predetermined value, the first heat load judgment means Regardless of the determination result, the engine idle speed is set to a third speed that is higher than the second speed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. 2, a throttle valve 12 is provided in an intake passage 11 of an engine 10, and a bypass passage 1 is provided in a passage 13 that bypasses the throttle valve 12.
An auxiliary air flow control valve (AAC valve) 14 for adjusting the auxiliary air flow passing through 3 is provided. AAC
The opening degree of the valve 14 is controlled by an idle speed control circuit 31, and the engine idle speed is controlled by adjusting the auxiliary air flow rate in accordance with the operating state of the engine or a command value from an air conditioning control circuit 26 described later. .

Reference numeral 20 denotes an air conditioner. The air conditioner 20 is supplied via a variable capacity compressor 21 driven by the engine 10 and a condenser, a liquid tank, and an expansion valve (not shown) which are compressed by the compressor 21. Evaporator 2 for evaporating the refrigerant and cooling the passing air
2 and a blower fan 23 that blows outside air introduced from an inlet (not shown) through the evaporator 22 and blows air into the vehicle interior.
And The compressor 21 is turned on / off by a command from an air conditioning control circuit 26 via a relay 25, and controls the discharge amount of the refrigerant according to a required amount of cooling capacity.

The blower fan 23 has an air conditioning control circuit 26.
Driven through a blower fan drive circuit 27 in response to a command from In the present embodiment, four stages of Hi, MH, ML, and Lo can be switched in the descending order of the speed (air volume) of the blower fan 23. The air-conditioning control circuit 26 includes:
An outside air temperature sensor 41 for detecting an outside air temperature Tamb, an indoor temperature sensor 42 for detecting a vehicle interior temperature Tinc, and a solar radiation sensor 43 for detecting an amount of solar radiation Qsun are connected, and an air conditioner switch operated when the compressor 21 is used. 44, a fan switch 45 for switching the operation / non-operation of the blower fan 23 and the speed is also connected.
Although the fan switch 45 is shown as a single switch for convenience, it is actually composed of a plurality of switches. The control circuit 26 turns on / off the compressor 21 or the blower fan 2 in accordance with the state of the air conditioner switch 44 or the blower fan switch 45 and the vehicle thermal load.
3 and the outside air temperature Tamb.
A command value for the engine idling speed is determined according to the blower fan speed and output to the idling speed control circuit 31.

Next, control for determining the engine idle speed in this embodiment will be described with reference to the flowcharts of FIGS. FIG. 3 shows the control performed by the air-conditioning control circuit 26. First, in step S1, it is determined from the state of the air-conditioning switch 44 whether the compressor 21 is on (operating). In step S2, the idle speed command value Ne is set to the idle speed N ₁ (corresponding to the first speed, for example, 650 rpm) when the compressor is off. This command value Ne
Is input to an idle speed control circuit 31, where actual idle speed control is performed, which will be described in detail with reference to FIG.

Meanwhile, when the compressor 21 is turned on the process proceeds to step S3, to determine the state N ₂ or N ₃ from the characteristics shown in accordance with the target air temperature Xm. Target outlet temperature Xm
Xm = (A + D) T′ptc + B · Tam + C · Q′sun−D · T
It is calculated by inc + E. Tam is the outside temperature sensor 4
The value obtained by processing the outside air temperature Tamb obtained from 1 so as to correspond to the actual outside air temperature excluding the influence from other heat sources, Q'sun, is the solar radiation amount information Qsun from the solar radiation sensor 43.
Is corrected to predetermined heat amount information, T'ptc is a value obtained by correcting the set temperature Tptc set on the control panel by the occupant according to the outside air temperature, and Tinc is the indoor temperature sensor 42.
And A to E are constants. Here, the target outlet temperature Xm decreases as the vehicle thermal load increases. At the time of auto control, the actual blow temperature, blower fan speed and blow outlet are controlled based on the target blow temperature. However, since this control is not directly related to the present invention, a detailed description thereof will be omitted.

[0013] In step S4 to determine the state determined in step S3, if N _3, the idling rotation speed command value Ne corresponds to a high N ₃ (third rotation speed than N ₁ in step S5 , For example, 850 rpm). On the other hand, if it is determined that N _2, the process proceeds to step S6,
In steps S6 to S8, the currently set blower fan speed is determined. If Hi, the process proceeds to step S9, and the reference value T1 of the outside air temperature is set to 20. Also M
If H, ML, Lo, steps S10, S11, S
At 12, T1 is set to 22, 24, and 26, respectively.

[0014] In step S13, based on the characteristics shown in the figure, the outside air temperature Tamb to determine whether state N ₁ or N ₂ depending on whether exceeds the reference value T1, which is the set. In step S14 determines the result, the idle speed command value Ne is set to N ₁ proceeds to step S2 if N _1, if N ₂ the command value Ne in step S15 N ₁ and N
₃ , an intermediate value N ₂ (corresponding to the second rotation speed, for example, 750
rpm). Here, the reference value T1 used in step S13 is set to be higher as the blower fan speed increases. As a result, the determination in step S14 determines whether the logical product of the outside air temperature Tamb and the blower fan speed is equal to or greater than a predetermined value. Is determined.

FIG. 4 shows only a part of the engine idling speed control procedure by the idling speed control circuit 31. In step S21, the idle speed command value Ne input from the air conditioning control circuit 26 is determined, and Ne ≠
N ₂ and Ne ≠ N _3, i.e. when it is determined not to perform the idle-up, in step S24, the opening degree of the AAC valve 14 is feedback controlled so that the actual engine idle speed N becomes N ₁ (650 rpm) . On the other hand, when step S21 is affirmed and it is determined that the idle-up control is to be performed, the process proceeds to step S25 and Ne
= N ₂ when it is determined that the AAC valve 1 in step S22
4 is opened by a certain value, and then the process proceeds to step S23.
The opening of the AAC valve 14 is feedback-controlled so that the engine idle speed N becomes N ₂ (750 rpm). Further, when it is determined that Ne = N ₃ in step S25, opens the AAC valve 14 by a predetermined value in step S26, then the process proceeds to step S27, AAC as engine idle speed is N ₃ (850 rpm) Valve 14 Is feedback-controlled.

As described above, in this embodiment, the thermal load on the evaporator 22 is estimated by the logical product of the outside air temperature and the blower fan speed, and when the logical product is equal to or more than a predetermined value, the engine idle speed is reduced to the normal value. Since the number of revolutions is held at the compressor off time, and when the logical product is less than the predetermined value, the idling number of revolutions is made higher than the above, so that
When it is not necessary to increase the idle speed (when the logical product is small), even if the compressor 21 is operated, the idle speed does not increase, and the fuel efficiency can be improved. Further, since there is no need to use a sensor immediately after the evaporation as in the conventional case, even when employing a system without a temperature sensor immediately after the evaporation, it is not necessary to newly provide a temperature sensor immediately after the evaporation, and the cost can be reduced.

Further, in this embodiment, when the target outlet temperature Xm is equal to or lower than a predetermined value when the compressor is turned on, that is, when the vehicle thermal load is equal to or higher than the predetermined value, the engine idle speed is changed to the normal engine speed (when the compressor is turned on). since so as to set to a higher rotational speed N ₃ than the second rotational speed) N _2, there is also an effect of obtaining a sufficient cooling power during high heat load. Also, if the engine idling speed is kept at N ₂ during a high heat load, the cooling power is insufficient and the blower fan is operated at a high speed for a long time. there is, according to this embodiment, the blower fan by setting the idle speed to the N ₃ is not being operated for a long time a high speed, the passenger will not be feel uncomfortable.

In the configuration of the above embodiment, the air-conditioning control circuit 26 includes the judging means 106, the heat load judging means 108, and the rotational speed commanding means (including a commanding unit and a reference value setting unit) 10.
7 is constituted. In the above description, the higher the blower fan speed, the higher the reference value of the outside air temperature is set, and the outside air temperature and the blower fan are determined by determining whether the detected outside air temperature is equal to or higher than the set reference value. Although it is determined whether the logical product of the speeds is equal to or greater than a predetermined value, the direction of the logical product determination is not limited to the embodiment. Further, the threshold value for determining the target blow-out temperature Xm used in FIG. 3 and the reference value of the outside air temperature determined by the blower fan speed are not limited to the illustrated values. Although the example in which the blower fan speed can be switched in four stages has been described, for example, one in which three or five or more stages can be switched may be used.

[0019]

According to the first aspect of the present invention, the thermal load on the evaporator is determined based on the logical product of the outside air temperature and the blower fan speed, and the idle speed is controlled based on the determination result. Can be determined, and an appropriate idle speed can always be set. According to the third aspect of the invention, at least when the heat load determined based on the vehicle interior temperature and the target value thereof is equal to or higher than a predetermined value, regardless of the heat load determined based on the outside air temperature and the fan speed. Since the engine idle speed is increased to the third speed, the occupant does not feel discomfort due to insufficient cooling.

[Brief description of the drawings]

[Fig. 1] Claim correspondence diagram

FIG. 2 is an overall configuration diagram of an embodiment of the present invention.

FIG. 3 is a flowchart illustrating an example of a procedure of engine idle speed command control;

FIG. 4 is a flowchart showing an example of a procedure of actual engine idle speed control;

[Explanation of symbols]

 Reference Signs List 10 engine 13 bypass passage 14 auxiliary air flow control valve 20 air conditioner 21 compressor 22 evaporator 26 air conditioning control circuit 31 idle speed control circuit 41 outside temperature sensor 26 control circuit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-59-156818 (JP, A) JP-A-2-23245 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60H 1/32 623

Claims (3)

(57) [Claims] 1. A compressor driven by an engine to compress a refrigerant, an evaporator for vaporizing the refrigerant compressed by the compressor, and a variable speed for blowing air introduced from outside of the vehicle through the evaporator into a vehicle interior. A blower fan, an outside air temperature sensor for detecting an outside air temperature, a judging means for judging a speed of the blower fan, and a heat load not less than a predetermined value when the outside air temperature is not less than a reference value.
A determination unit that determines that the blower fan speed is higher
A reference value setting unit that sets a low reference value for the outside air temperature
And et consisting heat load determining means, the compressor inoperative outputs a command signal to the engine idle speed and the first speed when the compressor operation, determine <br/> by the thermal load determining means Rotation speed command means for outputting a command for setting the engine idle rotation speed to a second rotation speed higher than the first rotation speed only when the interrupted heat load is equal to or more than a predetermined value. A vehicle air conditioner characterized by the above-mentioned. 2. The compressor according to claim 1, wherein said rotation speed command means comprises:
During operation, the vehicle interior temperature and the vehicle interior temperature target value are
If the heat load determined based on the above is equal to or greater than a predetermined value
The engine idle speed is changed to the second speed.
Output a command to set the third rotation speed even higher than
The vehicle air conditioner according to claim 1, wherein: 3. The refrigerant is compressed by being driven by an engine.
Compressor and an evaporator that vaporizes the refrigerant compressed by the compressor.
And the air introduced from outside the vehicle through the evaporator.
A variable speed blower fan that blows air into the vehicle interior, an outside air temperature sensor that detects an outside air temperature , a determination unit that determines the speed of the blower fan, and a heat load based on the outside air temperature and the blower fan speed.
A first thermal load determining means for determining a load, and at least a vehicle interior separate from the first thermal load determining means.
Determines thermal load based on target temperature and cabin temperature
To a second heat load determining means, (a) shows the compressor is not operated, the engine idle
Outputs a command signal to set the rotation speed to the first rotation speed
(B) when the compressor is operating and the second
The heat load determined by the heat load determining means is less than a predetermined value.
In this case, it was determined by the first heat load determining means.
The engine idle only when the heat load is equal to or higher than a predetermined value.
The rotation speed is a second rotation speed higher than the first rotation speed.
(C) when the compressor is operating
And the heat determined by the second heat load determining means.
If the load is equal to or greater than a predetermined value, the first heat load determination step is performed.
Engine idle speed regardless of the result of the
The third rotation speed is set to be higher than the second rotation speed.
Speed command means for outputting a command for
Characteristic vehicle air conditioner.