JP2002012022A - Air conditioner for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve fuel consumption during the operation of an engine brake. SOLUTION: This air conditioner for a vehicle is constituted to make an increase correction of an engine intake air quantity in an idling state according to compressor driving load and to control the refrigerant discharge capacity of a compressor according to cooling demand load. An engine braking state is detected, and the refrigerant discharge capacity of the compressor is minimized upon detecting the engine braking state. The compressor driving load is thereby reduced, and there is no need to increase the intake air quantity for driving the compressor before completing deceleration by the engine brake, so that the fuel consumption during the operation of the engine brake can be reduced.

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, and more particularly, to an improved control method of a variable displacement compressor.

[0002]

2. Description of the Related Art In an air conditioner for a vehicle which performs an so-called "idle-up" operation for increasing the intake air amount for driving a compressor when an engine is idling and rotating the engine, the idle-up is stopped when an engine brake is activated and the compressor is stopped. There is known an air conditioner for a vehicle in which the engine load is changed to an engine load and the engine brake is easily applied (for example, see JP-A-07-266854).

However, in the above-described apparatus, since the idle-up is stopped by detecting the operating state of the engine brake, a load for driving the compressor is applied to the engine when the deceleration by the engine brake ends and the engine returns to the idling state. The rotation speed is suddenly reduced, and there is a possibility that a sharp drop in the rotation speed or engine stall occurs.

In order to solve such a problem, if the rotation speed of the engine becomes equal to or lower than a set speed before the end of deceleration by the engine brake, the amount of intake air is increased according to the driving load of auxiliary equipment such as a compressor, and the idle speed is increased. There has been proposed a vehicle air conditioner that restarts up (for example, see Japanese Patent Application Laid-Open No. H11-148402).

[0005] However, in the latter device, when the vehicle travels in an urban area where acceleration and deceleration are repeated at a low speed, the frequency of increasing the intake air amount in accordance with the driving load of auxiliary equipment such as a compressor increases, and fuel efficiency deteriorates. There's a problem.

It is an object of the present invention to improve fuel economy when operating an engine brake.

[0007]

The present invention will be described with reference to FIG. 1 showing the configuration of an embodiment. (1) The invention according to claim 1 comprises a compressor 1 having a variable refrigerant discharge capacity and a compressor (1) compressor drive load detecting means (3) for detecting the drive load, intake air amount correcting means (9) for increasing and correcting the engine intake air amount during idling according to the compressor drive load, and cooling required load calculation for calculating the required cooling load. The present invention is applied to a vehicle air conditioner including means 4 and a compressor control means 4 for controlling the refrigerant discharge capacity of the compressor 1 according to the required cooling load. The compressor control means 4 includes an emblem detection means 9 for detecting an engine brake state.
Achieves the above object by minimizing the refrigerant discharge capacity of the compressor 1 when an engine brake state is detected. (2) According to the second aspect of the present invention, the compressor 1 having a variable refrigerant discharge capacity, the compressor driving load detecting means 3 for detecting the driving load of the compressor 1, and increasing the intake air amount during idling according to the compressor driving load. A vehicle air conditioner including an intake air amount correcting means 9 for correcting, a cooling required load calculating means 4 for calculating a cooling required load, and a compressor control means 4 for controlling a refrigerant discharge capacity of the compressor 1 according to the cooling required load. Applies to equipment. The compressor control means 4 includes an emblem detecting means 9 for detecting an engine brake state. The compressor control means 4 sets the compressor 1 to the minimum capacity when the engine brake state is detected and the required cooling load is equal to or less than a predetermined value. Achieve the above objectives. (3) In the vehicle air conditioner of the third aspect, the compressor driving load detecting means 3 detects a pressure on a refrigerant discharge side of the compressor 1 and sets the pressure as a driving load of the compressor. (4) In the vehicle air conditioner according to the fourth aspect, the cooling required load calculating means 4 includes: an evaporator blow-out air temperature, a solar radiation amount,
The target evaporator blow-out air temperature calculated based on the vehicle interior air temperature and the vehicle exterior air temperature is set as a cooling required load.

In the section of the means for solving the above-mentioned problems, a diagram of an embodiment is used for easy understanding of the description, but the present invention is not limited to the embodiment. .

[0009]

(1) According to the first aspect of the present invention, when the engine braking state is detected, the refrigerant discharge capacity of the compressor is minimized, so that the compressor driving load is reduced, and before the deceleration by the engine brake ends. Since it is not necessary to increase the amount of intake air for driving the compressor, it is possible to reduce fuel consumption when the engine brake is operated. (2) According to the second aspect of the invention, the compressor is set to the minimum capacity when the engine brake state is detected and the required cooling load is equal to or less than the predetermined value. When the operation state of the engine brake continues for a long time on a slope or the like, it is possible to prevent a decrease in air conditioner performance.

[0010]

FIG. 1 is a diagram showing the configuration of an embodiment. The compressor 1 is a variable displacement compressor driven by an engine (not shown), and the duty of the solenoid-operated control valve 1a changes the inclination of the swash plate 1b, thereby changing the stroke of the piston 1c to discharge the refrigerant. change. Condenser 2 as a heat exchanger outside the vehicle is a blower fan (not shown)
The high-temperature and high-pressure refrigerant discharged from the compressor 1 is cooled by the outside air introduced by the traveling wind pressure. The condenser 2 is provided with a pressure sensor 3 for detecting the refrigerant pressure Pd on the refrigerant discharge side of the compressor 1.
The refrigerant discharged from the condenser 2 passes through a well-known liquid tank, an expansion valve, and an evaporator as a vehicle interior heat exchanger, and returns to the compressor 1 again.

Air conditioner (A / C) control amplifier 4
Is composed of a microcomputer and peripheral parts such as a memory, and performs various calculations such as a target temperature of a vehicle air conditioner and various controls such as a compressor, an outlet, and an air volume. The A / C control amplifier 4 has an intake sensor 5 for detecting the temperature Tint of the conditioned air blown from the evaporator, a solar radiation sensor 6 for detecting the solar radiation Sun, an external air sensor 7 for detecting the vehicle interior temperature AMB, and a vehicle interior temperature Incar. Is connected. The A / C control amplifier 4 includes an evaporator blow-out wind temperature Tint, a solar radiation amount Sun, and an internal air temperature Inca.
A target evaporator outlet wind temperature Te0 is calculated based on r and the outside air temperature AMB, and a stroke control signal Duty of the compressor 1 for setting the evaporator outlet wind temperature Tint to the target value Te0 is output to the control valve 1a.

The ECM engine computer 9 is composed of a microcomputer and peripheral parts such as a memory. The ECM engine computer 9 controls the intake air amount by adjusting the opening of a throttle valve (not shown) of the engine, and also controls the fuel injection amount, ignition timing, etc. Control. The fuel injection amount of the engine basically increases and decreases in proportion to the intake air amount. The engine computer 9 is connected to a pressure sensor 3 for detecting a refrigerant discharge pressure Pb, an engine rotation sensor 10 for detecting an engine rotation speed Ne, a throttle opening sensor 11 for detecting a throttle valve opening TVo, and the like. The engine computer 9 detects the operating state of the engine brake on the basis of the engine rotation speed Ne and the throttle valve opening TVo, and sends it to the A / C control amplifier 4.

FIG. 2 is a flowchart showing a compressor control program by the A / C control amplifier 4 and the engine computer 9. The operation of the embodiment will be described with reference to this flowchart. The A / C control amplifier 4 and the engine computer 9 execute the respective compressor control programs shown in FIG. 2 at predetermined time intervals.

First, the engine computer 9 checks in step 1 whether the engine rotation speed Ne is higher than a predetermined idling rotation speed IDLE. If the engine rotation speed Ne is higher than the idling rotation speed IDLE, the process proceeds to step 2; Return to step 1. In step 2, it is determined whether or not the throttle valve opening TVo is equal to or smaller than a predetermined opening α. If the opening is equal to or smaller than the predetermined opening α, the process proceeds to step 3, otherwise returns to step 1. Where idling rotation speed ID
LE is the rotation speed when the engine is idling, and the predetermined throttle valve opening α is the throttle valve opening when the engine is idling.

The engine rotation speed Ne is higher than the idling rotation speed IDLE, and the throttle valve opening TVo
Is smaller than or equal to the predetermined opening degree α, it is determined that the engine brake is operating, and an engine brake state signal is transmitted to the A / C control amplifier 4.

In the following step 4, the refrigerant discharge pressure P
The correction amount of the engine intake air is controlled according to b. Normally, the engine computer 9 performs an increase correction (idle-up) of the intake air amount according to the driving load of the compressor 1 at the time of idling, and performs speed control so that the rotation speed at the time of idling becomes the target rotation speed. The refrigerant discharge pressure Pb of the compressor 1 is proportional to the compressor drive load. In this embodiment, the refrigerant discharge pressure Pb is detected and used as the drive load of the compressor 1, and the engine intake air is corrected according to the refrigerant discharge pressure Pb. Control the amount.

When the engine brake is activated, the engine computer 9 stops idle-up for driving the compressor, and makes the compressor an engine load, thereby making it easier to apply the engine brake. In addition, the deceleration by the engine brake ends and the engine returns to the idling state. At this time, the intake air correction amount is increased to prevent engine stall, and idle-up is restarted. The control of the intake air correction amount is performed by adjusting the opening of the throttle valve in an engine having an electronically controlled throttle valve, and in an engine having an auxiliary intake air control valve (AAC valve) in an auxiliary air passage. The adjustment is performed by adjusting the opening of the AAC valve.

The engine computer 9 includes steps 1 to
Operation 4 is repeatedly performed. Engine control such as intake air amount control, fuel injection control, ignition control, etc. other than at the time of idling, which is not directly related to the present invention, is well known, and a description thereof will be omitted.

On the other hand, the A / C control amplifier 4 determines in step 11 that the evaporator blow-out air temperature Tin
The target evaporator outlet wind temperature Te0 is calculated based on t, the amount of solar radiation Sun, the inside temperature Incar, and the outside temperature AMB.

In the following step 12, it is confirmed whether or not an engine brake state signal has been received from the engine computer 9. If the engine brake state signal has been received, the routine proceeds to step 13, otherwise proceeds to step 16. When the engine brake state signal is received, it is checked in step 13 whether or not the target evaporator blowing air temperature Te0 is equal to or higher than a predetermined temperature β. The target evaporator blow-out air temperature Te0 represents a cooling required load. When the target evaporator blow-out air temperature Te0 is equal to or higher than the predetermined temperature β, it is determined that the cooling required load is small. If the required cooling load is equal to or smaller than the predetermined value β, the process proceeds to step 14; otherwise, the process proceeds to step 16.

When the engine is in the brake state and the required cooling load is equal to or smaller than the predetermined value β, the stroke control signal Duty of the compressor 1 is set to 0 in step 14, and the destroke (minimum capacity) signal of Duty = 0 is set in step 15 Is output to the solenoid control valve 1a of the compressor 1.

On the other hand, when the engine is not in the braking state,
Alternatively, if the required cooling load is larger than the predetermined value β even in the engine braking state, a stroke control signal Duty of the compressor 1 for calculating the evaporator blow-out wind temperature Tint to the target value Te0 is calculated in step 16, and the stroke control is performed in step 15. The signal Duty is output to the control valve 1a.

The A / C control amplifier 4 performs step 1
The operations 1 to 16 are repeatedly executed. The control of the outlet and the control of the amount of the blown air, which are not directly related to the present invention, are well known, and the description thereof will be omitted.

As described above, the correction of the intake air amount increase (idle-up) for driving the compressor during the operation of the engine brake is stopped, and the correction of the intake air amount increase is restarted when the deceleration by the engine brake ends and the engine returns to the idling state. In an air conditioner for vehicles, when the engine braking condition and the required cooling load are below a predetermined value, the compressor is set to the minimum capacity. Even if the correction for increasing the intake air amount for driving is frequently repeated, the amount of increase in the intake air amount is small because the compressor driving load is small, and therefore, the fuel consumption amount during the operation of the engine brake can be reduced.

Further, even in the engine braking state, if the required cooling load is larger than a predetermined value, the compressor is not destroked and the compressor is controlled in accordance with the required cooling load. When it continues, it is possible to prevent a decrease in air conditioner performance.

In the above-described embodiment, an example has been described in which, even in the engine braking state, when the required cooling load is larger than a predetermined value, the compressor does not destroke and the compressor is controlled in accordance with the required cooling load. In this state, the compressor may be forcibly destroke regardless of the required cooling load. In this case, when the operating state of the engine brake continues for a long time on a downhill or the like, the fuel consumption at the time of operating the engine brake can be reduced as compared with the above-described embodiment.

In the above-described embodiment, an example has been described in which the refrigerant discharge pressure of the compressor is detected and used as the driving load of the compressor. However, the method of detecting the compressor driving load is not limited to the above-described embodiment. In the above-described embodiment, the target evaporator outlet air temperature is calculated based on the evaporator outlet air temperature, the amount of solar radiation, the vehicle interior air temperature, and the vehicle exterior air temperature, and the target evaporator outlet air temperature is used as a cooling required load. Although an example has been described, the method of calculating the required cooling load is not limited to the above-described embodiment.

In the structure of the above embodiment, the compressor 1 is a compressor, the pressure sensor 3 is a compressor driving load detecting means, the engine computer 9 is an intake air amount correcting means and an emblem detecting means,
The A / C control amplifier 4 constitutes cooling demand load calculation means and compressor control means.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment.

FIG. 2 is a flowchart showing an operation of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 1a Solenoid control valve 1b Swash plate 1c Piston 2 Condenser 3 Pressure sensor 4 A / C control amplifier 5 Intake sensor 6 Solar radiation sensor 7 Outside air sensor 8 Inside air sensor 9 Engine computer 10 Engine rotation sensor 11 Throttle opening sensor

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F02D 29/04 F02D 29/04 B H

Claims (4)

[Claims] 1. A compressor having a variable refrigerant discharge capacity, a compressor drive load detecting means for detecting a drive load of the compressor, and an intake air amount correction for increasing an engine intake air amount during idling according to the compressor drive load. Means for calculating a required cooling load; means for calculating a required load for cooling; and a compressor control means for controlling a refrigerant discharge capacity of the compressor according to the required load for cooling. An air conditioner for a vehicle, comprising: an emblem detection unit, wherein the compressor control unit minimizes a refrigerant discharge capacity of the compressor when an engine brake state is detected. 2. A compressor having a variable refrigerant discharge capacity, a compressor driving load detecting means for detecting a driving load of the compressor, and an intake air amount correction for increasing an engine intake air amount during idling according to the compressor driving load. Means for calculating a required cooling load; means for calculating a required load for cooling; and a compressor control means for controlling a refrigerant discharge capacity of the compressor according to the required load for cooling. The compressor control means includes an emblem detection means, and when the engine brake state is detected, and the cooling request load is equal to or less than a predetermined value,
An air conditioner for a vehicle, wherein the compressor has a minimum capacity. 3. The air conditioner for a vehicle according to claim 1, wherein the compressor driving load detecting means detects a pressure on a refrigerant discharge side of the compressor and sets the detected pressure as a driving load of the compressor. Characteristic vehicle air conditioner. 4. The vehicle air conditioner according to claim 1, wherein said cooling demand load calculating means calculates based on an evaporator blowing air temperature, a solar radiation amount, a vehicle cabin air temperature and a vehicle cabin air temperature. A vehicle air conditioner, wherein the target evaporator blow-out air temperature is used as a cooling demand load.