JPH0436037A - Idle speed controller of engine - Google Patents

Abstract

PURPOSE:To restrain rotational variation caused by excess or lack of a load compensation quantity inputted according to erroneous operation of the outside load within the control width of feedback control by receiving an output of an outside load detection means, and varying the control width of feedback control by a control means according to the magnitude of the outside load. CONSTITUTION:Engine speed is stably maintained at a target engine speed by a control means 40 while being feedback-controlled to the target engine speed at the time of idling operation. When the operation condition of an outside load is detected by an outside load detection means 43, the control width of feedback control of the control means 40 is varied by a control width varying means 42 according to the magnitude of the outside load. When a load compensation quantity following the operation of the outside load is inputted, rotational variation caused by excess or lack of the load compensation quantity is restricted within the control width of the feedback control by the control means 40 so as to prevent outburst of the idle speed or engine stall.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine idle speed control device, and more particularly to an improvement in an engine idle speed control device that performs feedback control of the engine speed to a target speed during idling operation.

(Prior Art) Conventionally, as an idle speed control device that performs feedback control so that the engine speed becomes the target speed during idling operation of the engine, for example, the Japanese Patent Publication No. 64-118
As disclosed in Publication No. 16, a control valve is provided in a bypass passage that bypasses a throttle valve provided in the intake passage, and during idling operation, this control valve is adjusted to control the amount of intake air flowing through the bypass passage. By doing so, the idle speed is feedback-controlled to the target speed, and
A known system is known in which the target rotational speed is changed depending on the state of an external load such as an air conditioner, and the intake air amount of the bypass passage is increased or decreased by a predetermined value as a load correction for the external load.

(Problem to be Solved by the Invention) By the way, in the above-mentioned conventional system, when the engine rotation speed is feedback-controlled to the target rotation speed, the feedback correction amount, which is the control amount, is set to a predetermined upper limit value and lower limit value. The controllable rotation speed range was determined within a predetermined control range. This is because if the control width is too wide, it becomes easy to pick up noise in the engine rotational speed signal, causing reliability problems such as difficulty in maintaining stable engine rotation.

On the other hand, usually external loads such as air conditioners, alternators,
When a torque converter, etc. is in operation, a uniform load correction amount preset according to each external load is applied and load correction is executed, preventing rotation drop due to external loads and reducing the idle rotation speed. I try to maintain it.

However, since this load correction amount is uniformly determined for each external load, it may not always be able to respond well to the actual external load due to variations in the engine and variations in each external load. . In particular, as the external load increases, the amount of deviation of the load correction amount from the actual external load increases, and as a result, the large amount of deviation of the load correction causes large rotational fluctuations in the idle rotation. Then, in order to correct this, the feedback control is executed, and if the deviation in load correction is large and the rotational fluctuation exceeds the control range, this cannot be absorbed and problems such as revving of the idle speed or stalling of the engine occur.

The present invention has been made in view of the above points, and its purpose is to perform feedback control of the engine speed to a target speed during idling operation, and to correct the load due to an external load acting on the engine. When this is executed, the purpose is to prevent the idle speed from racing or the engine from stalling due to an excess or deficiency of the load correction amount.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, in the feedback control during idling operation, when an external load acts on the engine and the load correction is executed, the control of the feedback control is performed. The width is changed according to the size of the external load.

Specifically, the solution taken by the present invention is, as shown in FIG.
and a rotation speed detection means 36 for detecting the rotation speed of the engine; and upon receiving the output of this rotation speed detection means 36, the rotation speed adjustment means 41 is adjusted to a predetermined value so that the engine rotation speed becomes the target rotation speed during idling operation. The present invention is based on an engine idle speed control device including a control means 40 that performs feedback control in a control range. An external load detection means 43 detects the state of an external load acting on the engine, and upon receiving the output of this external load detection means 43, the control width of the feedback control by the control means 40 is adjusted according to the magnitude of the external load. The configuration includes a control width changing means 42 for changing the control width.

(Function) With the above configuration, in the present invention, the control means 40:
During idling, the engine speed is feedback-controlled to the target speed, and the engine speed is stably maintained at the target speed. At that time, if the external load detection means 43 detects the operating state of the external load, the control width changing means 42
According to the magnitude of the external load, the control means 4
The control width of feedback control of 0 is changed. For this reason, when applying the load correction amount due to the operation of the external load, the rotation fluctuation due to the excess or deficiency of this load correction amount is controlled by the control means 4
The rotational speed can be kept within the control range of the feedback control based on 0, and the above-mentioned rotational fluctuation is reliably corrected, and revving of the idle rotation or engine stalling is prevented.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows an engine equipped with an idle speed control device according to an embodiment of the present invention. This engine is connected to an automatic transmission. In FIG. 2, 1 is an engine, and this engine 1 includes a cylinder block 3 forming a cylinder 2, a cylinder head 4 joined to the upper surface of this cylinder block 3, and a piston 5 that reciprocates within the cylinder 2. A combustion chamber 6 is formed within the cylinder 2, which is defined by the lower surface of the cylinder head 4 and the top surface of the piston 5.

A spark plug 7 is provided facing the combustion chamber 6. 8 is an ignition coil that generates a secondary voltage for ignition; 9 is drivingly connected to the output shaft of the engine, and is connected to the spark plug 7;
and a distributor connected to the ignition coil 8, which distributes the secondary voltage from the ignition coil 8 to the spark plugs 7 of the cylinders in the combustion stroke.

An intake passage 10 is connected to the combustion chamber 6, and an intake valve 11 is provided at the opening to the combustion chamber 6 to introduce intake air into the combustion chamber 6 at a predetermined timing. In this intake passage 10, a throttle valve 12 for adjusting the amount of intake air, a surge tank 13 for absorbing intake pulsation, etc., and an injector 14 for injecting and supplying fuel are arranged in order from upstream. Furthermore, the intake passage 1
0 is provided with a bypass passage 15 that bypasses the throttle valve 12, and a control valve 16 that adjusts the amount of bypass intake air flowing through the bypass passage 15 is disposed in the middle of this bypass passage 15. The control valve 16 is duty-controlled by the bypass passage 15 and the control valve 16 to adjust the amount of bypass intake air, thereby adjusting the amount of intake air to the engine 1. It consists of

Further, an exhaust passage 17 is connected to the combustion chamber 6, and an exhaust valve 18 is provided at the opening to the combustion chamber, so that exhaust gas is discharged from the combustion chamber 6 at a predetermined timing. This exhaust passage 17 is provided with a catalyst 19 for purifying exhaust gas.

The operations of the ignition coil 8, injector 14, and control valve 16 are controlled by a control unit 50 containing a CPU.

Furthermore, in FIG. 2, 30 is an intake temperature sensor that detects the intake air temperature on the upstream side of the throttle valve 12, 31 is a hot wire type air flow sensor that detects the amount of intake air, and 32 is an idle switch that closes when the throttle valve 12 is fully opened. ,
33 is a throttle position sensor that detects the opening degree of the throttle valve 12; 34 is a water temperature sensor that detects the engine cooling water temperature; and 35 is a sensor 02 that is arranged upstream of the catalyst 19 in the exhaust passage 17 and detects the oxygen concentration in the exhaust gas. A sensor 36 is a rotation speed sensor as a rotation speed detection means for detecting the engine rotation speed by detecting the crank angle, and a shift sensor 37 is an external load detection means for detecting the shift range position of the automatic transmission 60.
38 is a vehicle speed sensor that detects the running speed of the vehicle, and 39 is an air conditioner switch as external load detection means that outputs an ON signal when the air conditioner driving compressor installed as an auxiliary device in the engine 1 is activated.

The output signals of the sensors and switches 30 to 39 are input to the control unit 50.

Next, the control valve 16 by the control unit 50
The operation control will be explained based on the flowchart of FIG. In the figure, after starting, various signals from sensors are read in step S1. Next, in step S2, it is determined whether the engine 1 is in idle operation. In this case, it is determined that the engine is in idle operation when the idle switch 32 is ON when the throttle valve 12 is fully closed and the engine speed is below a predetermined speed.

Here, if the answer is No, which is not idling operation, the process proceeds to step S14, where a control amount G corresponding to the operating state is calculated, and in step S15, this control amount G is output to the control valve 16, and the process returns. On the other hand, when YES in step S2 indicates that the idle operation is in progress, in order to execute feedback control of the bypass intake air amount, first, in step S3, the target rotation speed N
. are set based on the map shown in FIG. In this map, the target rotation speed N. is determined by the engine water temperature, and is set high because the lower the engine water temperature, the lower the combustion stability. Then, in step S4, a basic control amount CB corresponding to the target rotational speed No. is set based on the map shown in FIG. This basic control amount aS is also the target rotation speed N. It has similar characteristics and is determined by the engine water temperature. Next, in step S5, maximum value (plus side) and minimum value (minus side) guards are set for the feedback correction amount of feedback control obtained in the following steps. That is, this guard is set by the positive side MAX guard which is the maximum value and the negative side WIN guard which is the minimum value of the feedback correction amount GFH according to the external load conditions shown in Table 1 below.

Table 1 Here, when the vehicle speed is 5fi/H or more, it is when the vehicle is in a creep running state, and in this case, the load on the engine due to the torque converter is much smaller than when the vehicle is stopped. It is possible, and the vehicle speed is 51ai
If it is less than /H, it is considered that the torque converter is fully loaded, which is almost the same as when the vehicle is stopped. Therefore, the load size is D in descending order of magnitude.
Range & vehicle speed 5) as/H or higher, D range & air conditioner O
N & vehicle speed 5km/H or more, D range & vehicle speed 51as/H
D range, air conditioner ON, and vehicle speed less than 5 km/h, and the MIN guard is expanded accordingly. In other words, the control range widens according to the magnitude of the load. In this case, the MAX guard on the positive side is uniformly the same, but this means that even if the air volume increase in the direction of rotation increase on the positive side is slightly overcorrected, it will not have a big effect, but on the contrary, the air volume decreases on the negative side. If it is corrected too much to the negative side, it will have a negative effect on drivability such as engine stalling, so set the M value on the negative side.
The control width is changed by changing only the IN guard. still,
In the N range, the engine operates by itself in a completely unloaded state, and is set separately from when it is under load.

Next, in step S6, the target engine speed N is calculated from the actual engine speed Ne. Calculate the rotational deviation ΔNe from . Further, in step S7, the deviation Δ of the feedback correction amount according to the rotational deviation ΔNe is determined based on the map shown in FIG.
Find GFB. Then, in step S8, the feedback correction amount GFB is set to the previous feedback correction amount GPB-
It is determined by adding the above deviation ΔGFB to r. Furthermore, in step s9, the feedback correction amount GFB is changed to step s.
It is determined whether the feedback correction amount set in step 5 is larger than the MAX guard. Here, if it is larger than the MAX guard, the process proceeds to step SIO, where the feedback correction amount GFB is set to the MAX guard, and the process proceeds to step S+3. On the other hand, when the feedback correction amount GFB is less than the MAX guard, the process proceeds to step Sl+;
This time, it is determined whether the feedback correction amount GFB is smaller than the MIN guard. Here, if it is smaller than the MIN guard, the process proceeds to step S+2, sets the feedback correction amount GFB to rule N guard, and proceeds to step SI3. On the other hand, if it is equal to or higher than the MIN guard, the process directly advances to step S13. Then, in step S13, the final control amount G is determined by adding the feedback correction jlGFB and other corrections ji G c to the basic control amount aS.

Here, the other correction amount Gc is set in response to an external load such as the ON operation of the air conditioner or the D range. Then, in step S15, the final control amount G
is output to the control valve 16 and returned.

In the above flow, in all steps, the control means 40 receives the output of the rotation speed sensor 36 and performs feedback control of the rotation speed adjustment means 41 in a predetermined control width so that the engine rotation speed becomes the target rotation speed during idling operation. It consists of Further, step SI5 and steps 89 to 51
2 constitutes a control width changing means 42 which receives the output of the external load detection means 43 and changes the control width of the feedback control by the control means 40 according to the magnitude of the external load.

Therefore, in the embodiment described above, feedback control is executed to control the bypass intake air amount by the control valve 16 so that the engine rotation speed becomes the target rotation speed during idle operation, and a stable idle rotation speed is obtained. At this time, when an external load is applied due to the ON operation of an air conditioner or the D range of an automatic transmission, the control range of the feedback control is expanded according to the magnitude of the external load. Therefore, it is possible to compensate for excesses or deficiencies in the load correction amount caused by the difference between the load correction amount applied when an external load is applied and the actual load variation, etc., and keep it within the control range of feedback control. It is possible to reliably correct the rotational fluctuation caused by the excess or deficiency of the load correction amount, thereby preventing the engine from revving up in idle rotation or stalling the engine.

Furthermore, since the control width of the feedback control is changed according to the vehicle speed so that it becomes smaller as the vehicle speed increases, it is possible to prevent the engine from stalling when sudden braking is applied during creep driving. In other words, during creep driving at a vehicle speed of 5 b/h or more, the load due to the torque converter is actually quite small, even though the load correction amount set according to the load due to the torque converter is applied. Therefore, the feedback correction amount is largely corrected to the negative side in order to compensate for the excessive bone in the load correction amount. In this case, the WIN guard restricts the feedback correction amount to the negative side, so even if the torque converter is suddenly loaded due to sudden braking, etc., the feedback correction will not be over-corrected to the negative side. This can prevent sudden rotational drop or engine stalling due to

In addition to the external loads described in the above embodiments, there are alternators, power steering pumps, etc., and the present invention is also applicable to these.

(Effects of the Invention) As explained above, according to the engine idle speed control device of the present invention, when performing feedback control in a predetermined control width so that the engine speed becomes the target speed during idling operation, When an external load is applied, the predetermined control width of the feedback control described above is changed according to the size of the external load, so it is possible to prevent excess or deficiency in the amount of load correction applied as the external load operates. It is possible to keep rotational fluctuations due to minute changes within the control range of feedback control, and it is possible to reliably correct the rotational fluctuations and prevent revving of idle speed or stalling of the engine.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 6 show embodiments of the present invention, FIG. 2 is a schematic diagram of the overall configuration, FIG. 3 is a flowchart showing the control of the control valve in the control unit, and FIG. 4 is a diagram showing the target rotation speed. FIG. 5 is a map diagram of the basic control amount, and FIG. 6 is a map diagram of the feedback correction amount. 1... Engine 10... Intake passage 12... Throttle valve 15... Bypass passage 16... Control valve 36... Rotation speed sensor 37... Shift sensor 38... Vehicle speed sensor 39...・・Air conditioner switch (external load detection means) 40
... Control means 41 ... Rotation speed adjustment means 42 ... Control width changing means 43 ... External load detection means 50 ... Control unit 60 ... Transmission (rotation speed detection means) (External load detection Means) 1... Engine 10... Intake passage 12... Throttle valve 15... Bypass passage 16... Control valve 36... Rotation speed sensor (rotation speed detection means) 37...
Shift sensor (external load detection means) 38...Vehicle speed sensor 39...Air conditioner switch (external load detection means) 40
... Control means 41 ... Rotation speed adjustment means 42 ... Control width changing means 43 ... External load detection means 50 ... Control unit 60 ... Transmission water temperature diagram Water temperature diagram 4

Claims (1)

[Claims] (1) a rotation speed adjusting means for adjusting the engine rotation speed;
A rotation speed detection means for detecting the rotation speed of the engine, and based on the output of the rotation speed detection means, the rotation speed adjustment means is feedback-controlled within a predetermined control width so that the engine rotation speed becomes the target rotation speed during idling operation. In an engine idle speed control device, the engine idle speed control device includes: an external load detection means for detecting the state of an external load acting on the engine; and control width changing means for changing the control width of feedback control by the control means.