JPH07139405A - Engine idle control device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an idling control device having a simple intake pipe structure and a low cost by controlling the air flow rate by driving a throttle valve with a motor without providing a bypass pipe for supplying auxiliary air. [Structure] Water temperature sensor 5 and shift position switch 9,
Air conditioner operation switch 10, power steering operation switch 11
The target engine speed is determined by the load information such as the above, and the throttle opening determination means 19 determines the throttle opening so that the actual engine speeds match. Drive circuit 20
Drives the motor 4, opens and closes the throttle valve, and adjusts the air flow rate to control the idling speed to a proper value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an engine of, for example, an automobile, which controls the opening / closing of a throttle valve by driving a motor to adjust the amount of air supply and the amount of fuel injection and ignition timing. Thus, the present invention relates to an engine idling control device that secures a stable operating state during idling.

[0002]

2. Description of the Related Art An engine stall is apt to occur when an engine is idling when the cooling water temperature is low, or when a load such as an air conditioner or power steering is applied during idling. Therefore, as shown in FIG. 14, a method is used in which a bypass pipe that connects the upstream side and the downstream side of the throttle valve is provided in the intake pipe, and auxiliary air is supplied from the bypass pipe according to the load state of the engine.

[0003]

However, when the bypass pipe is provided, the first problem is that the structure of the intake pipe becomes complicated.

Further, in an idling control device configured to control the fuel injection amount based on the engine speed and the intake pipe pressure, when the engine speed is lowered due to a load such as an air conditioner or power steering, the intake pipe is changed as shown in FIG. 15 (a). The pressure rises and the amount of fuel injection increases, which acts in the direction of increasing the engine speed.
As shown in Fig. 5 (b), the sensitivity of the pressure sensor in the intake pipe to the engine speed decreases, so the intake pipe pressure hardly changes, and the fuel injection amount does not act to increase the engine speed. The second problem is that the rotation of the engine will decrease and eventually cause an engine stall.

Further, the conventional planar throttle valve is
As shown by the broken line in FIG. 12, since the intake air amount shows a flow rate characteristic in which the amount of intake air increases sharply when the valve is only slightly opened from the fully closed state,
To control a minute air flow rate while idling, a pulse motor with a high stepping number or a servomotor control system using a high-resolution encoder is required, which leads to a significant cost increase. is there.

In view of the above, the present invention eliminates a bypass pipe for supplying auxiliary air by opening and closing a throttle valve with a motor to control the air flow rate during idling, and is a simple and low-cost engine idling control device. The purpose is to provide.

Further, the idling control of the engine which secures a stable operating state of the engine against load and disturbance by determining the fuel injection amount and the ignition timing at idling by the engine speed, the throttle opening and the intake pipe pressure. The purpose is to provide a device.

It is another object of the present invention to provide a highly accurate idling control device for an engine by using a throttle valve whose air flow rate gradually increases with respect to the throttle opening from a fully closed throttle opening to a predetermined range. .

[0009]

In order to solve the above-mentioned problems, the present invention eliminates a bypass pipe for supplying auxiliary air as a first means, and the engine operating conditions such as the intake air amount and the cooling water temperature and the transmission condition. Throttle opening command value that determines the throttle opening command value so that the difference between the actual engine speed and the target engine speed setting means that is set according to the shift position and the operating state of the air conditioner or power steering is zero. A determining means is provided, and the motor is driven to open / close the throttle valve in accordance with the output signal from the throttle opening command value determining means.

As a second means, a fuel injection amount determining means for determining the fuel injection amount based on the opening degree of the throttle valve and the engine speed and an ignition timing determining means for determining the ignition timing are provided to control the fuel during idling. It is characterized by performing ignition timing control.

As a third means, a throttle valve having a characteristic of gradually increasing the air flow rate is provided as compared with a conventional planar throttle valve from a fully closed throttle opening to a predetermined range. To do.

[0012]

According to the first means having the above structure,
Since there is no bypass pipe for supplying auxiliary air, the structure of the intake pipe is simple and the cost is low.

According to the second means, the fuel injection amount determining means for determining the fuel injection amount according to the opening degree of the throttle valve and the engine speed and the ignition timing determining means for determining the ignition timing are provided, and the fuel control during idling is performed. Therefore, even if the sensitivity of the intake pipe pressure sensor with respect to the engine speed decreases, it is possible to ensure a stable engine operating state against load and disturbance.

Further, according to the third means, since the air flow rate gradually increases with respect to the throttle opening from the fully closed throttle opening to a predetermined range, a pulse motor having a high stepping number and a high resolution are provided. It is possible to control the minute air flow rate in the idling state without adopting the control system by the servo motor using the encoder.

Thus, highly accurate idling control can be realized simply and at low cost.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram mainly showing an embodiment of an engine idling control device of the present invention. Reference numeral 1 is an engine, 2 is an intake pipe that supplies air to the engine 1, and 3 is an intake pipe that is arranged in the intake pipe 2 and is opened and closed by being rotated by a motor 4 to adjust the amount of air supplied to the engine 1. Is. Reference numeral 5 is a water temperature sensor for detecting the temperature of the engine cooling water, and 6 is a rotation speed sensor, which is attached to the crankshaft and generates a synchronization signal for each predetermined angle of the crankshaft to detect the rotation speed of the engine. Reference numeral 7 is an intake air flow rate sensor for detecting the amount of intake air, and 8 is a throttle opening sensor for detecting the opening of the throttle valve 3. 9 is a shift position switch for detecting the shift position of the transmission, 10 is an air conditioner operating switch for detecting whether the air conditioner is operating, and 11 is a power steering operating switch for detecting whether the power steering is operating. is there. Reference numeral 12 is an idling control device of the present invention, and outputs of a microcomputer, a RAM (random access memory), a ROM (read only memory), a water temperature sensor 5, an intake air amount sensor 7, and a throttle opening sensor 8. -To-digital converter (A / D converter) for converting fuel to digital value and spark plug 1
A control circuit for controlling an igniter 14 connected to the engine 3, a control circuit for controlling an injector 15 arranged in the intake pipe 2 for supplying fuel to the engine 1, and a drive circuit for the motor 4 for opening and closing the throttle valve 3 are included. Has been.

The idling control device 12 drives the motor 4 according to the operating conditions of the engine such as the intake air amount sensor 7 and the water temperature sensor 5, the shift position of the transmission, the operating conditions of the air conditioner and power steering, and the throttle valve. Opening / closing control of 3 is performed to adjust the intake air amount.

FIG. 2 shows an example of the throttle valve mechanism of this embodiment. The throttle valve 3 is arranged in the intake pipe 2 of the engine 1 and is rotatably held around a valve shaft 16 as a rotation center. A return spring 17 is attached to the right end portion of the valve shaft 16 and always urges the valve shaft 16 to close the throttle valve 3. Also, the valve shaft 16
Is connected to a motor 4, and the throttle valve 3 drives the motor 4 and is opened and closed via a valve shaft 16.

FIG. 3 is a block diagram of the idling control device 12. The idling control device 12 of the present invention is provided with a target engine speed determining means 18, a throttle opening determining means 19 and a drive circuit 20 for driving a motor.

In the target engine speed determining means 18, the water temperature sensor 5, the load position information such as the shift position switch 9, the air conditioner operating switch 10, the power steering operating switch 11 and the like are used to determine the target engine rotational speed by searching or calculating from the graph shown in FIG. For example, in the graph of FIG. 4A, the basic rotation speed NBASE is determined from the output value Tw of the water temperature sensor 5. If the air conditioner is operating, the correction value NAC due to the load is determined from the graph of FIG. Further, when the shift position of the transmission is other than N (neutral) and P (parking), that is, when the engine output is transmitted to the drive system of the vehicle, FIG.
The correction value ND is determined from the graph of (d). In this way, the target engine speed Nref is obtained by the sum of the basic speed NBASE and the correction value according to the load condition, that is, (Equation 1).

[0022]

[Equation 1] Nref = NBASE + NAC + ND (1) Similarly, when only the power steering is operating, the target engine speed Nre can be determined from the graphs of FIGS. 4 (a) and 4 (c).
f is obtained by (Equation 2).

[0023]

[Equation 2] Nref = NBASE + NPC (2) In the throttle opening degree determining means 19, based on the deviation so that the actual engine speed becomes the target engine speed,
Proportional compensation by (Equation 3), integral compensation by (Equation 4),
The throttle opening θcom (m) is determined by using the differential compensation by (Equation 5) and (Equation 6).

[0024]

[Equation 3] θp (m) = kp × (N (m) −Nref (m)) (3)

[0025]

[Equation 4] θi (m) = ki × (N (m) −Nref (m)) + θi (m-1) (4)

[0026]

[Formula 5] θd (m) = kd × (N (m) −Nref (m)) (5)

[0027]

## EQU00006 ## .theta.com (m) =. Theta.p (m) +. Theta.i (m) +. Theta.d (m) (6) Generally, the proportional coefficient kp, integral coefficient ki, and differential coefficient kd in this type of control means are constant, In the field of engine control, control in synchronism with a crank angle signal for measuring the engine speed is indispensable. Therefore, as the engine speed increases, the control cycle becomes shorter and the proportional coefficient k
If p, the integral coefficient ki, and the differential coefficient kd are kept constant, the actual coefficient becomes large, so that a control system as designed cannot be obtained, and stable idling control becomes difficult. Therefore, in the idling control device of the present invention, the control characteristics as designed can be realized by changing the proportional coefficient kp, the integral coefficient ki, and the differential coefficient kd according to the engine speed as shown in FIG. There is.

In this way, the drive circuit 20 drives the motor 4 according to the control signal from the throttle opening determining means 19,
By opening and closing the throttle valve 3 and adjusting the air flow rate, the idling speed is controlled to an appropriate value.

The operation of this embodiment will be described with reference to FIG. 6 in the above configuration. When the idling control device 12 is powered on, the CPU is reset and Step 1
Initialize the RAM, input / output interface circuit, timer, etc. When the initial setting is completed, the background processing 1000 is repeatedly executed. In the background processing 1000, in step 11, the temperature of the engine cooling water is detected by the water temperature sensor 5, and in step 12, the shift position switch 9 of the transmission,
Air conditioner operation switch 10, power steering operation switch 11
The load condition applied to the engine 1 is detected from. In step 13, the target engine speed determination means 18 determines the target engine speed Nref from the graph shown in FIG. 4 according to the engine cooling water temperature and load conditions detected in steps 11 and 12, and the process proceeds to step 11 again. .

On the other hand, when an external interrupt signal is input while the background processing 1000 is being executed, the interrupt processing 2000 is executed with priority. The interrupt process 2000 is activated by a signal generated by the rotation speed sensor 6 at each predetermined crank angle of the engine 1, and a process synchronized with the engine rotation speed is executed. At step 21, the engine speed N is detected by the engine speed sensor 6, and the intake air flow rate sensor 7 is operated.
The intake air amount is detected by the throttle opening sensor 8, and the throttle opening is detected by the throttle opening sensor 8. In step 22, the ignition timing is determined from the engine speed, the intake air amount, the engine cooling water temperature, etc., and the ignition timing is controlled by turning on and off the primary current to the igniter 14 and generating a spark in the spark plug 13. In step 23, the fuel injection amount and injection timing are determined from the engine speed, intake air amount, engine cooling water temperature, etc., and the injector 1
Fuel control is performed by supplying fuel from 5 to the engine 1, and the routine proceeds to step 24. In step 24, the throttle opening determining means 19 obtains the proportional coefficient kp, the integral coefficient ki, and the differential coefficient kd from the graph shown in FIG. 5 based on the engine speed N detected in step 21, and in step 25, in step 13 The throttle opening is determined by performing the calculations of (Equation 3) (Equation 4) (Equation 5) (Equation 6) so that the determined rotation speed Nref and the actual engine rotation speed N detected in step 21 match. In step 26, the drive circuit 20 drives the motor 4 in response to the control signal from the throttle opening determination means 19, controls the throttle valve to adjust the air flow rate, and returns to the background processing 1000. In this way, proper control of the idling speed can be realized with the intake pipe having a simple structure without the bypass pipe for supplying the auxiliary air.

Next, an embodiment of the second means of the present invention will be described. In FIG. 7, fuel injection amount determination means 2
1, injector control circuit 22, ignition timing determination means 2
3. The igniter control circuit 24 is provided in the idling control device 12 of the present invention. The fuel injection amount determining means 21 has a typical value of the throttle opening θn (n =
0, 1, 2, ...) and a typical value of engine speed Nm (m
= 0, 1, 2, ...) are stored. The detected value N of the engine speed sensor 6 and the detected value θ of the throttle opening sensor 8 are respectively

[0032]

If θ (n) ≦ θ <θ (n + 1) N (m) ≦ N <N (m + 1), then f (mn), f (m n + 1), f (m + 1 n),
The fuel injection amount f is determined by linearly interpolating from four values of f (m + 1n + 1). When the fuel injection amount is determined in this way, a control signal is output to the injector control circuit 22 and fuel is supplied from the injector 15 to the engine 1.

Further, the ignition timing determining means 23 has a representative value of the throttle opening θj (j = 0, 1, 2, ...
・) And a representative value of the engine speed Ni (i = 0, 1, 2, ...
..) is stored in the table. The detected value N of the engine speed sensor 6 and the throttle opening sensor 8
Detected value θ of

[0034]

If θ (j) ≦ θ <θ (j + 1) N (i) ≦ N <N (i + 1), then Ig (ij), Ig (i j + 1), Ig (i + 1
The ignition timing Ig is determined by linearly interpolating from the four values j) and Ig (i + 1 j + 1), and the igniter control circuit 2
At 4, the ignition timing is controlled by turning on and off the primary current to the igniter 14 to generate a spark on the spark plug 13.

Next, the operation of this embodiment will be described with reference to FIG. The background processing is the same as in the case of FIG. 6 for explaining the first embodiment. When an external interrupt signal is input while the background processing 1000 is being executed, the interrupt processing 3000 is preferentially executed. This interrupt processing 3000 is activated by a signal generated from the rotation speed sensor 6 at each predetermined crank angle of the engine 1, and processing that is synchronized with the engine rotation speed is executed. Step 31
Then, the engine speed N is detected by the engine speed sensor 6, and the routine proceeds to step 32. In step 32, the throttle opening determining means 19 obtains the proportional coefficient kp, the integral coefficient ki, and the differential coefficient kd from the graph shown in FIG. 5 based on the engine speed N detected in step 31, and then the step 13
The throttle opening is determined by carrying out the calculations of (Equation 3) (Equation 4) (Equation 5) (Equation 6) so that the revolution speed Nref determined in step 1 and the actual engine revolution speed N match. In step 33,
The drive circuit 20 drives the motor 4 in response to a control signal from the throttle opening determination means 19 to control the throttle valve and adjust the air flow rate. In step 34, the throttle opening sensor 8 detects the throttle opening, and the process proceeds to step 35. In step 35, the ignition timing determination means 23 determines the ignition timing from the engine speed N and the throttle opening θ by the above-mentioned method from the table shown in FIG. 9 and controls the ignition timing. In step 36, the fuel injection amount determining means 21 determines the fuel injection amount from the engine speed N and the throttle opening θ from the table shown in FIG. When the interrupt process 3000 is completed in this way, the process returns to the background process 1000, and the background process is executed until an interrupt signal is input again.

As described above, during idling, even if the sensitivity of the intake pipe pressure sensor with respect to the engine speed decreases, it is possible to ensure a stable engine operating state against load and disturbance.

Next, one embodiment of the third means of the present invention will be described. FIG. 11 is a sectional view taken along line AA of FIG. Nozzles 26 and 27 are formed on the outer peripheral surface of the throttle valve 25 and extend upstream and downstream, respectively. Even if the throttle valve 25 is rotated about the valve shaft 16 from the fully closed state by a small angle Δφ, the opening formed by the end surface of the throttle valve 25 and the inner wall of the intake pipe 2 is not affected by the nozzle portions 26 and 27. Open slowly. As shown by the solid line in FIG. 12, the flow rate characteristic is that the throttle opening θ is within a predetermined range (0
<Θ <ψ) has a characteristic that the air flow rate gradually increases with respect to the throttle opening. This characteristic is
It can be arbitrarily selected depending on the shapes of 6 and 27. Similar characteristics can be obtained with an S-shaped curved surface as shown in FIG. 13 or with a nozzle portion formed at its tip. By devising the shape of the throttle valve in this way, the flow rate characteristic in the throttle opening θ from fully closed to a predetermined range is made gentle, and the control of a minute air amount during idling is relatively low in precision with a pulse motor or It can be realized with a servo motor.

Each means of the present invention can be realized by using a dedicated hardware circuit having each of those functions.

[0039]

As is apparent from the above description,
According to the first aspect of the present invention, since the bypass pipe for supplying the auxiliary air is not provided, the structure of the intake pipe is simple and the cost is low.

According to the second means, the fuel injection amount determining means for determining the fuel injection amount according to the opening degree of the throttle valve and the engine speed and the ignition timing determining means for determining the ignition timing are provided, and the fuel control during idling is performed. Therefore, even if the sensitivity of the intake pipe pressure sensor with respect to the engine speed decreases, it is possible to ensure a stable engine operating state against load and disturbance.

Further, according to the third means, since the air flow rate gradually increases with respect to the throttle opening from the fully closed throttle opening to the predetermined range, a pulse motor having a high stepping number or a high resolution is used. It is possible to control the minute air flow rate in the idling state without adopting the control system by the servo motor using the encoder.

Thus, highly accurate idling control can be realized simply and at low cost.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of an idling control device according to an embodiment of the present invention.

FIG. 2 is a throttle valve mechanism according to an embodiment of the present invention.

FIG. 3 is a block diagram of the idling control device.

FIG. 4 is a conceptual diagram of a graph of a target rotation speed determination unit of the idling control device.

FIG. 5 is a conceptual diagram of a graph of a control coefficient of a throttle opening degree determining unit of the idling control device.

FIG. 6 is a flowchart showing the operation of the idling control device.

FIG. 7 is a block diagram of an idling control device according to a second embodiment of the present invention.

FIG. 8 is a conceptual diagram of a table of a fuel injection amount determination means of the second embodiment.

FIG. 9 is a conceptual diagram of a table of ignition timing determination means of the second embodiment.

FIG. 10 is a flowchart showing the operation of the idling control device of the second embodiment.

11 is a cross-sectional view taken along the line AA of FIG.

FIG. 12 is a graph showing flow rate characteristics of a conventional throttle valve and a throttle valve in the third embodiment.

FIG. 13 shows an example of a throttle valve in the third embodiment.

FIG. 14 is a configuration diagram of a conventional idling control device.

FIG. 15 is a graph showing characteristics of intake pipe pressure depending on engine speed.

[Explanation of symbols]

 1 Engine 2 Intake Pipe 3 Throttle Valve 4 Motor 5 Water Temperature Sensor 6 Rotation Speed Sensor 7 Intake Air Flow Rate Sensor 8 Throttle Opening Sensor 9 Shift Position Switch 10 Air Conditioner Operation Switch 11 Power Steering Operation Switch 12 Idling Control Device 13 Spark Plug 14 Igniter 15 Injector 16 valve shaft 17 return spring 18 target engine speed determining means 19 throttle opening determining means 20 drive circuit 21 fuel injection amount determining means 22 injector control circuit 23 ignition timing determining means 24 igniter control circuit 25 throttle valve by third means 26 Upstream side nozzle section 27 Downstream side nozzle section

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location F02D 43/00 301 BK

Claims (7)

[Claims] Claim: What is claimed is: 1. An engine idling control device for controlling an idle speed to an appropriate value in accordance with an engine operating condition such as engine speed, intake air amount, cooling water temperature, etc. An idling control device for an engine, which does not have a bypass pipe for supply, and which opens and closes a throttle valve arranged in the intake pipe by driving a motor to adjust an air supply amount. 2. A target engine speed setting means which is set in accordance with an operating condition of the engine such as an intake air amount, a cooling water temperature, a shift position of a transmission, an operating condition of an air conditioner or a power steering, and a target engine speed thereof. The throttle opening command value determining means for determining the throttle opening command value so that the difference between the engine speed and the actual engine speed becomes zero, and the motor is operated according to the output signal from the throttle opening command value determining means. 2. The engine idling control device according to claim 1, wherein the throttle valve is opened and closed by driving it. 3. The throttle opening command value determining means determines a proportional compensating element, an integral compensating element, and a differential compensating element based on the deviation between the target engine speed determined by the target engine speed and the actual engine speed. And the proportionality coefficient,
3. The engine idling control device according to claim 1, wherein the integral coefficient and the differential coefficient are increased or decreased according to the engine speed to determine the throttle opening. 4. Fuel control and ignition timing control at idling, comprising fuel injection amount determination means for determining a fuel injection amount based on the opening of a throttle valve and engine speed, and ignition timing determination means for determining an ignition timing. The idling control device for an engine according to claim 1, wherein: 5. A throttle valve, compared with a flat-shaped throttle valve, when the throttle opening is from a fully closed state to a predetermined range,
2. The engine idling control device according to claim 1, wherein the idling control device has a shape capable of gradually increasing the air flow rate. 6. A nozzle portion extending toward the upstream side is formed on the outer peripheral surface of the portion that moves downstream when opening with respect to the flow of the throttle valve, and the portion that moves upstream when opening with respect to the flow. The outer peripheral surface of the nozzle is formed with a nozzle portion extending toward the downstream side, and the nozzle shape is formed so that the opening area of the throttle valve and the intake pipe changes more gently than in the case without the nozzle. The engine idling control device according to claim 1 or 5, characterized in that: 7. The throttle valve has a substantially S-shaped cross section when cut in the flow direction of air or air-fuel mixture, and the portion that moves downstream when opening with respect to the flow is concave in the flow direction. The idling control device for an engine according to claim 1 or 5, wherein the portion having the curved surface shape and moving upstream with respect to the flow has a curved surface shape convex in the flow direction.