JPH0533700A - Idling speed controller of engine - Google Patents

Abstract

(57) [Abstract] [Purpose] An engine idle speed control device for controlling the idle speed according to the load of the compressor. By-passing the throttle valve 2 and first flow rate adjusting means 1, 5 for controlling an air flow rate by controlling an opening of a valve provided in a first air flow path 4 bypassing the throttle valve 2. A predetermined value in a vehicle air conditioner is used in an engine idle speed control device that includes second flow rate adjusting means 7 and 9 for opening and closing a valve provided in the second air flow path 8 to adjust the air flow rate. Pressure detection means 1 for detecting the above refrigerant pressure
0b, the engine speed is controlled by the first flow rate adjusting means 1 and 5 so that the idle speed of the engine increases by a first predetermined amount in response to the operation of the vehicle air conditioner, and the pressure detecting means 10b. When a refrigerant pressure equal to or higher than a predetermined value is detected by, the second air flow passage 8 is opened by the second flow rate adjusting means 7 and 9 so that the idle speed of the engine increases by the second predetermined amount. Together with the first flow rate adjusting means 1, 5
The control means 6, 17, 18 for controlling the engine speed is provided, and the idle speed is controlled according to the load of the compressor 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle speed control device for an engine equipped with an air conditioner.

[0002]

2. Description of the Related Art There is known an engine idle speed control device for increasing an engine idle speed by operating an air conditioner compressor to cope with an increase in engine load (for example, Nissan new model vehicle manual U12-2). 1989
(See October).

In this type of device, when the air-conditioning switch is turned on, the engine speed control device activates the compressor and opens the auxiliary air flow rate control valve provided in the passage bypassing the throttle valve to allow idling rotation. The number is increased to cope with the increase in compressor load. However, when the outside air temperature detected by the outside air temperature sensor is cold, for example, 10 ° C. or less, the load on the compressor is light and the idle speed does not need to be increased, and the auxiliary air flow rate control valve is not opened. In order to protect the vehicle air conditioner, the pressure Pd of the refrigerant is detected by the pressure switch provided in the liquid tank, and the operation of the compressor is stopped when the pressure Pd is below a predetermined value Pd1 or above a predetermined value Pd3. To do.

[0004]

However, in the conventional engine idle speed control device, the outside air temperature sensor operates by blowing back the high temperature air in the engine room, and the auxiliary air temperature is assisted even when the actual outside air temperature is 10 ° C. or less. There is a problem that the air flow rate control valve is opened to increase the idle speed.

Further, even when the abnormal pressure is detected by the pressure switch provided in the liquid tank and the operation of the compressor is stopped, the outside air temperature sensor keeps the temperature of 10 degrees C.
When the above outside air temperature is detected, there is also a problem that the auxiliary air flow rate control valve is opened to increase the idle speed.

An object of the present invention is to provide an idle speed control device for an engine, which controls the idle speed according to the load of the compressor.

[0007]

The present invention will be described with reference to FIG. 1 which is a diagram corresponding to the claims. In the present invention, the opening of a valve provided in a first air passage 4 that bypasses a throttle valve 2 will be described. Flow rate adjusting means 1, 5 for controlling the air flow rate to control the air flow rate, and a second air flow rate adjusting means for opening and closing the valve provided in the second air flow path 8 bypassing the throttle valve 2 The present invention is applied to an engine idle speed control device provided with the flow rate adjusting means 7 and 9. Then, the pressure detecting means 10b for detecting the refrigerant pressure in the vehicle air conditioner equal to or higher than a predetermined value, and the first so that the idle speed of the engine is increased by a first predetermined amount in response to the operation of the vehicle air conditioner. When the pressure detecting means 10b detects a refrigerant pressure equal to or higher than a predetermined value, the engine speed is controlled by the flow rate adjusting means 1 and 5 of FIG. Control means 6, 17 for controlling the engine speed by the first flow rate adjusting means 1, 5 while opening the second air flow path 8 by the second flow rate adjusting means 7, 9.
And 18 to achieve the above object.

[0008]

The control means 6, 17, 18 rotate the engine by the first flow rate adjusting means 1, 5 so that the idle speed of the engine is increased by the first predetermined amount in response to the operation of the vehicle air conditioner. When the pressure detection means 10b detects a refrigerant pressure equal to or higher than a predetermined value by controlling the number, the second flow rate adjusting means 7 and 9 adjust the idle speed of the engine to increase by a second predetermined amount. The second air flow path 8 is opened, and the engine speed is controlled by the first flow rate adjusting means 1 and 5.

Incidentally, in the section of means and actions for solving the above problems for explaining the configuration of the present invention, the same reference numerals as the elements of the embodiments corresponding to the reference numerals of the respective means are used to make the present invention easy to understand. However, the present invention is not limited to the examples.

[0010]

FIG. 2 is a block diagram showing the structure of an embodiment. In the figure, 1 is a flow path 3 of the throttle valve 2.
It is an idle speed correction valve (hereinafter referred to as an AAC valve) provided in the flow path 4 that bypasses, and is opened / closed by a proportional solenoid 5. The proportional solenoid 5 is turned on / off at a predetermined frequency by the control circuit 6, and the air flow rate increases as the on time is longer than the off time.
As a result, the idle speed increases. That is, A
The AC valve 1 controls the idle speed during steady operation to a constant value, and drives the AAC valve 1 in the opening direction when a relatively large electric load, hydraulic pump load, compressor load, etc. are applied to the engine during idling. Then, the air flow rate is increased from the flow path 4 that bypasses the throttle valve 2, and the idle speed is increased according to the increase of the engine load. The control circuit 6 includes a microcomputer and its peripheral components, and executes a control program described later to control the idle speed of the engine.

Reference numeral 7 denotes an idle speed correction valve (hereinafter referred to as a FICD valve) provided in another passage 8 that bypasses the passage 3 of the throttle valve 2 and is opened / closed by a solenoid 9. That is, when the FICD valve 7 is opened by the solenoid 9, the air flowing in from the flow path 8 is added to the air flowing in through the flow path 3, and the idle speed of the engine is increased by the amount of increase in the air flow rate. .. In the device of the present invention, when the vehicle air conditioner is operated, the opening degree of the AAC valve 1 is first controlled to increase the idle speed, which corresponds to the increase in the compressor load.
When the increase in the compressor load cannot be dealt with even when the AAC valve 1 is fully opened, the FICD valve 2 is opened to increase the idle speed.

Reference numerals 10a and 10b are pressure detection switches provided in the liquid tank 11, as shown in FIG. The vehicle air conditioner includes a well-known compression refrigeration cycle including a compressor 12, a condenser 13, a liquid tank 11, an expansion valve 14 and an evaporator 15. The load state of the compressor 12 in the compression refrigeration cycle is the inside of the liquid tank 11. Is proportional to the refrigerant pressure Pd. As shown in FIG. 4, when the pressure Pd of the refrigerant discharged from the compressor 12 and pressure-fed through the condenser 13 becomes a predetermined value Pd1 or less, or a predetermined value Pd3 or more, the switch 10a is opened and the refrigerant pressure Pd is predetermined. When the value becomes Pd2 or more, the switch 10b is closed. In addition,
The predetermined value Pd1 is the minimum pressure that prevents the water attached to the surface of the evaporator 15 from freezing when the temperature of the refrigerant vaporizes too much, and the predetermined value Pd3 causes the equipment in the compression refrigeration cycle to burst. Is the highest pressure to prevent. Further, the predetermined value Pd2 is a limit pressure at which the AAC valve 1 alone can cope with an increase in engine load when the compressor 12 operates without opening the FICD valve 7.

Reference numeral 12a is a solenoid for turning on and off the magnet clutch of the compressor 12. When the solenoid 12a is turned on, the magnet clutch is closed and the compressor 12 is driven by the engine via the belt. The compressor 12 may be either of a fixed capacity type or a variable capacity type. 16 is also
An air conditioning switch for starting the vehicle air conditioner, 17 is a delay relay, the air conditioning switch 16 is turned on, and the pressure switch 10a is closed, that is, the refrigerant pressure Pd is Pd1 <.
When Pd <Pd3 is normal, it is turned on (hereinafter, the excited state of the relay coil is called on). The contact 17a of the delay relay 17 is closed after a predetermined time has passed since the relay 17 was turned on. When the air conditioning switch 16 is turned on and the pressure switch 10a is closed, the Lo level signal is input to the terminal 6a of the control circuit 6 via the coil of the relay 17. Further, reference numeral 18 is a relay that is turned on when the switch 10b is closed, and when the refrigerant pressure Pd in the liquid tank 11 becomes equal to or higher than a predetermined value Pd2 when the air conditioning switch 16 is turned on and the relay 17 is turned on, the switch 10b is turned on.
Is closed to excite the FICD solenoid 9, the relay 18 is turned on, and the Lo level signal is input to the terminal 6b of the control circuit 6 via the contact of the relay 18.

FIG. 5 is a flow chart showing a control program executed by the control circuit 6. The control operation of the idle speed will be described with reference to this flowchart. This control program is executed when the engine is idling. In step S1, the air conditioning switch 16 is turned on according to the input signal level of the terminal 6a, and the pressure detection switch 10a is closed, that is, it is determined whether the refrigerant pressure Pd in the liquid tank 11 is Pd1 <Pd <Pd3, and the determination is affirmative. If so, step S2 follows. If not, step S2.
Go to 5. When the air conditioning switch 16 is turned on, if the refrigerant pressure Pd is normal, the delay relay 17 is turned on, and the terminal 6a of the control circuit 6 is connected to the ground via the coil of the relay 17, the pressure switch 10a, and the air conditioning switch 16. Then, a Lo level signal is input to the terminal 6a.
As will be described later, when the terminal 6a of the control circuit 6 is at the Lo level and the terminal 6b is at the Lo level, the control circuit 6 drives and controls the proportional solenoid 5 to rotate N2 revolutions from the idle revolution number No when the air conditioner is stopped. If the terminal 6b is in the Hi level, the idle speed No is N1
Idle up only for rotation. Here, N1>N2> 0
Is. In any case, if the air conditioning switch 16 is turned on and the refrigerant pressure Pd is normal, the engine is idled up. Then, after a predetermined time, the delay relay 1
The contact point 17a of No. 7 is closed, power is supplied from the battery BAT to the solenoid 12a of the magnetic clutch of the compressor 12, the clutch is closed, and the compressor 12 is started. That is, by starting the compressor 12 after a lapse of a predetermined time after the engine is idled up, it is possible to prevent the engine from stall due to a sudden increase in load when the compressor 12 is started.

Next, in step S2, it is determined whether or not the refrigerant pressure Pd in the liquid tank 11 is larger than a predetermined value Pd2 based on the input signal level of the terminal 6b. If affirmative, the process proceeds to step S3, and if negative. Go to step S4.
When the refrigerant pressure Pd is larger than the predetermined value Pd2, the rotation speed obtained by adding the predetermined rotation speed increase N1 to the reference idle rotation speed N0 is set as the idle rotation speed set value N in step S3.
At this time, the power B is supplied to the solenoid 9 of the FICD valve 7.
Electric power is supplied from the AT through the relay contact 17a and the switch 10b, the solenoid 9 is excited, the FICD valve 7 is open, and the idle speed is increased.

On the other hand, when it is determined in step S2 that the refrigerant pressure Pd is less than or equal to the predetermined value Pd2, in step S4, the rotation speed obtained by adding the predetermined rotation speed increase N2 to the reference idle rotation speed N0 is set to the idle rotation speed. Let the value be N. That is, when the refrigerant pressure Pd is lower than the predetermined value Pd2, the increase of the compressor load is low, and the load increase of the compressor 12 can be dealt with only by opening the AAC valve 1, and the AAC valve 1 can be opened without opening the FICD valve 7. Control the opening of to idle up. In addition, in step S1, the air conditioning switch 1
When it is determined that 6 is not input or the refrigerant pressure Pd in the liquid tank 11 is abnormal, it is not necessary to idle up, so in step S5, the reference idle speed N0 is set to the idle speed setting. Let the value be N.

Next, in step S6, the actual rotation speed rpm detected by an unillustrated engine tachometer is compared with the idle rotation speed setting value N determined in the above step, and the actual rotation speed rpm is set. If it is lower than the value N, the operation proceeds to step S7. If the actual rotation speed rpm is higher than the set value N, the operation proceeds to step S8. When the actual rotation speed rpm is equal to the set value N, the operation returns to step S1. Step S7
Then, the duty of the drive signal of the proportional solenoid 5 is adjusted, and the AAC valve 1 is opened so that the actual rotation speed rpm becomes the idle rotation speed set value N. On the other hand, in step S8, the AAC valve 1 is closed so that the actual rotation speed rpm becomes equal to the idle rotation speed setting value N.

Thus, when the air conditioning switch 16 is turned on and the refrigerant pressure Pd is normal, the AAC valve 1
Is controlled to idle up the engine by a predetermined amount N2, and the compressor is started after a predetermined time. When the load on the air conditioner increases and the refrigerant pressure Pd2 that is equal to or higher than the predetermined value is detected, the FICD valve 7 is opened and A
The AC valve 1 was controlled to idle up by a predetermined amount N1. As a result, the idle speed of the engine is accurately controlled in accordance with the operation of the compressor 12 of the air conditioner and the load state thereof, and the engine idles up or operates when the outside air temperature is low and the compressor load is light as in the conventional case. There is no such thing as going idle when not being done.

In the above embodiment, the idle rotation speed increments N1 and N2 are set to satisfy N1>N2> 0, but they may be set to satisfy N1 = N2> 0.

In the configuration of the above embodiment, the pressure detection switch 10b serves as pressure detection means, the control circuit 6, the delay relay 17 and the relay 18 serve as control means, the idle speed correction valve (AAC valve) 1 and the proportional solenoid 5 are provided.
Constitutes the first flow rate adjusting means, and the idle speed correction valve (FICD valve) 7 and the FICD valve solenoid 9 constitute the second flow rate adjusting means.

[0021]

As described above, according to the present invention, the engine is controlled by the first flow rate adjusting means so that the idle speed of the engine is increased by the first predetermined amount in response to the operation of the vehicle air conditioner. The second flow rate adjusting means opens the second air passage so that the engine speed is controlled and when the refrigerant pressure above a predetermined value is detected, the idle speed of the engine is increased by a second predetermined amount. Since the engine speed is controlled by the first flow rate adjusting means, the compressor stops due to a malfunction of the outside air temperature sensor when the outside air temperature is below 10 degrees C or the refrigerant pressure of the air conditioner is abnormal. It is possible to obtain an idle speed according to the operation of the air conditioner and its load state without idling up when the vehicle is in operation.

[Brief description of drawings]

FIG. 1 is a diagram for responding to a complaint.

FIG. 2 is a block diagram showing the configuration of an embodiment.

FIG. 3 is a diagram showing a compression refrigeration cycle of an air conditioner.

FIG. 4 is a diagram showing an operating state of a pressure detection switch with respect to a refrigerant pressure.

FIG. 5 is a flowchart showing an example of an idle speed control program.

[Explanation of symbols]

 1 Idle speed correction valve (AAC valve) 2 Throttle valve 3, 4, 8 Flow path 5 Proportional solenoid 6 Control circuit 7 Idle speed correction valve (FICD valve) 9 FICD valve solenoid 10a, 10b Pressure detection switch 11 Liquid tank 12 Compressor 12a Magnet clutch solenoid 16 Air conditioning switch 17 Delay relay 17 Relay contact 18 Relay

Claims (1)

Claim: What is claimed is: 1. A first flow rate adjusting means for adjusting an air flow rate by controlling an opening of a valve provided in a first air flow path that bypasses a throttle valve, and the throttle valve. And a second flow rate adjusting means for opening and closing a valve provided in a second air flow path for bypassing the engine to adjust the air flow rate. Pressure detecting means for detecting the refrigerant pressure, and the first flow rate adjusting means for changing the engine speed so that the idle speed of the engine increases by a first predetermined amount in response to the operation of the vehicle air conditioner. The second flow rate adjusting means controls the second flow rate adjusting means to increase the idle speed of the engine by a second predetermined amount when the pressure detecting means detects a refrigerant pressure equal to or higher than the predetermined value. sky of An idle speed control device for an engine, comprising: a control means for opening an air flow path and controlling the engine speed by the first flow rate adjusting means.