JPH0660580B2 - Engine fuel controller - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control device for an engine, and more particularly to a device for controlling a fuel supply amount in an automobile engine according to an operating region of the engine.

(Prior Art) In an engine for an automobile, for example, Japanese Patent Publication No. 59-1
As shown in Japanese Patent No. 1736, there are cases where the operating region is divided into a plurality of regions and optimal fuel control is performed for each region. As an example, the following control may be performed.
That is, as shown in FIG. 4, the regions except the idle region A of low load (low throttle opening) and low rotation in the entire operating region of the engine with the engine speed and the throttle opening as parameters are the first and the first. The two boundary lines X and Y define a high load region B, a low load region C, and a region D in which the engine on the lower load side is in a decelerating operation state. Then, in the high load region B, feedback control is performed to maintain the air-fuel ratio at an optimum value so that good exhaust performance and fuel efficiency performance can be obtained while ensuring the required output performance, and in the low load region C, In order to stabilize the combustion state, which tends to become unstable under low load, open control is performed to constantly supply a fixed amount of fuel larger than the fuel supply amount in high load region B, and exhaust performance in deceleration operation region D In order to improve fuel efficiency and fuel efficiency, fuel cut control is performed to stop the supply of unnecessary fuel.

By the way, in such fuel control, the first and second boundary lines X and Y that divide the regions B, C, and D are the no-load lines of the engine, that is, the throttle opening and the engine rotation during no-load operation. Line Z showing the relationship with the number
Is set as a standard. That is, the first boundary line X between the feedback control region (high load region) B and the open control region (low load region) C is located near the no-load line Z on the high load side, and the open control region C and the fuel cut region ( The second boundary line Y with the deceleration operation region D is set on the low load side of the no-load line Z, respectively.

However, such a boundary line or area setting method causes the following problems. That is, the idle area A
When the so-called racing operation is performed in which the accelerator pedal is depressed while the transmission is in neutral, the engine speed rises above the no-load line Z in accordance with the throttle opening and shifts from the idle region A to the open control region C. However, in this state, when an air conditioner compressor or an oil pump for power steering that acts as an external load on the engine operates, the operating region of the engine moves from above the no-load line Z in the direction of arrow (a). Feedback control area B
Will rush into. Also, when the racing operation is performed in the state where the external load is applied to the engine, the open control area C may enter the feedback control area B. Then, when there is such a transition of the region, the fuel control system changes suddenly from the open control to the feedback control, and along with this, the fuel supply amount sharply decreases. The operating condition becomes extremely unstable, such as when it falls into

(Object of the Invention) The present invention defines the operating region of an engine by a boundary line set on the high load side in the vicinity of the no-load line, and the fuel supply amount on the low load side of the line is higher than that on the high load side. This is to deal with the above problems in the case of increasing the control, and when an external load such as a compressor for an air conditioner acts on the engine during racing operation or stepping on the accelerator pedal, If you perform the above racing operation, etc. while the load is acting,
Even if the operating region shifts beyond the boundary line, the fuel supply amount should not be sharply reduced. Accordingly, it is an object of the present invention to prevent the engine speed from dropping due to the shift of the operating range as described above and to maintain the operating state of the engine in a stable state.

(Structure of the Invention) The fuel control device for an engine according to the present invention is characterized by having the following structure in order to achieve the above object.

That is, as shown in FIG. 1, the region determination means 1 which receives the engine speed signal S ₁ and the throttle opening signal S ₂ to determine which region the engine operating state is in the preset zone. And a fuel supply control means 3 for controlling the fuel supply amount from the fuel supply device 2 in accordance with the area determined by the determination means 1, and the area determination means 1 has a height near the no-load line. When the area defined by the boundary line located on the load side is set and the area determined by the determination means 1 is on the low load side of the boundary line, the fuel control means 3 causes the high load of the boundary line. In the configuration in which the fuel supply amount is controlled to be increased with respect to the time of the side, the neutral detecting means 4 for detecting the neutral state of the transmission provided in the power transmission system of the engine, and the neutral detecting means 4. When the means 4 detects the neutral state of the transmission, providing the correcting means 5 for correcting the fuel control by the fuel supply control means 3. When the transmission is in the neutral state, the correction means 5 makes a boundary line with respect to the fuel supply control means 3 even if the operation area determined by the area determination means 1 is on the high load side of the boundary line. It operates so as to perform fuel control according to the region on the low load side. Therefore, when a racing operation is performed while the transmission is in neutral, when an external load acts on the engine during this operation, or when a racing operation is performed while the external load is acting, Even if the operating region of the engine shifts from the low load side to the high load side of the boundary line, the fuel control continues to perform the supply amount increase control in the low load side region.

(Effect of the Invention) As described above, according to the present invention, the operating region of the engine is defined by the boundary line set on the high load side in the vicinity of the no-load line, and the operating region of the engine is defined by the boundary line on the low load side. In an engine designed to perform control to increase the fuel supply amount during the region, an external load such as an air conditioner compressor acts at the time of a racing operation, or a racing operation while the external load is acting. When the operation range is changed from the low load side to the high load side of the boundary line, the fuel control continues to perform the supply amount increase control in the low load side region. As a result, it is possible to prevent the engine speed from dropping due to a sudden decrease in the fuel supply amount when the above-mentioned region is shifted, and to stabilize the operating state of the engine in such a case.

(Example) Hereinafter, the Example of this invention is described.

As shown in FIG. 2, the engine 10 is provided with an intake passage 14 communicating with the combustion chamber 13 through intake and exhaust valves 11 and 12, respectively.
And an exhaust passage 15 are provided. An air flow sensor 16 and a slot valve 1 are installed in the intake passage 14 from the upstream side.
7 and a fuel injection nozzle 18 and bypass passage 1 bypassing the throttle valve 17
9 is provided, and the bypass passage 19 is provided with a bypass control valve 20 that controls the amount of bypass air supplied to the combustion chamber 13 through the passage 19. Further, the exhaust passage 15 is provided with an air-fuel ratio sensor 21 for detecting the ratio of the fuel and air supplied to the combustion chamber 13 based on the residual oxygen concentration in the exhaust gas, etc., that is, the air-fuel ratio. A spark plug 22 is provided.

On the other hand, the engine 10 is provided with a controller 23 that controls the fuel injection amount from the fuel injection nozzle 18 and the opening degree (duty ratio) of the bypass control valve 20. The controller 23 includes an air flow rate signal a from the air flow sensor 16, a throttle opening degree signal b from a throttle opening degree sensor 24 for detecting the opening degree of the slot valve 17, and a rotation speed sensor for detecting the engine speed. 25, an engine speed signal c from the air-fuel ratio sensor 25, an air-fuel ratio signal d from the air-fuel ratio sensor 21, and a load signal e from a load sensor 26 for detecting the operation of an external load such as an air conditioner compressor or a power steering oil pump. ,
A neutral signal f from a neutral sensor 27 that detects a neutral state of a transmission (not shown) provided in a power transmission system from the engine 10 to the driving wheels of the automobile is input.

Then, the controller 23 determines the engine 10 based on the throttle opening signal b and the engine speed signal c.
Of the bypass passage 19 by controlling the opening degree of the bypass control valve 20 by outputting the control signal g to the bypass control valve 20 when the operating area of the bypass passage 19 is determined. By adjusting the amount of bypass air passing through, the idling speed is made to converge to a predetermined target idling speed. In this case, when the external load is operating, the controller 23 receives the signal e from the load sensor 26 and corrects the target idle speed to a higher value so that the corrected target idle speed is achieved. The opening degree of the bypass control valve 20 or the amount of bypass air is controlled.

Further, the controller 23 sets the basic injection amount of fuel to be injected from the fuel injection nozzle 18 based on the air flow rate signal a and the engine speed signal c, and also the throttle opening signal b and the engine speed signal c. The basic injection amount is corrected according to the operating region of the engine 10 determined from the above, and the control signal h 1 is output to the fuel injection nozzle 18 so as to obtain the corrected injection amount. That is, engine 1
When the operating region of 0 is in the feedback control region B on the high load side of the first boundary line X shown in FIG. 4, the air-fuel ratio sensor 2
When the signal d from 1 is input and the air-fuel ratio indicated by the signal d is leaner than the predetermined air-fuel ratio, the fuel injection amount is increased, and when it is richer than the predetermined air-fuel ratio, the fuel injection amount is increased. A control signal h is output to the fuel injection nozzle 18 so as to reduce the injection amount, and thus the air-fuel ratio is controlled so as to converge to the predetermined air-fuel ratio. Further, when the operating region is in the open control region C between the first and second boundary lines X and Y in FIG. 4, the fuel injection amount is a fixed amount larger than the amount injected in the feedback control region B. Control signal to the fuel injection nozzle 18 so as to maintain this amount of injection.
Output h. Further, the operating region is the second boundary line Y in FIG.
When in the fuel cut region D on the lower load side, a control signal to stop the fuel injection from the fuel injection nozzle 18
Output h. Here, as described above, the first and second boundary lines X and Y that define the regions B, C and D are the engine 1
The no-load line Z of 0 is set as a reference, and the high load side and the low load side in the vicinity thereof are set. Then, by performing the fuel control as described above according to the regions B, C, and D defined by these boundary lines X and Y, respectively, the required output performance and the favorable combustion state are maintained in each region. However, the exhaust performance and fuel efficiency will be improved.

However, the controller 23 performs the following correction control in addition to the fuel control according to the operation range as described above. That is, when the signal f indicating that the transmission from the neutral sensor 27 is in the neutral state is input, when the operating region of the engine 10 shifts from the open control region C to the feedback control region B, the controller 23 opens. The control for maintaining the fuel injection amount in the control region C at a constant increased amount is continuously performed.

Next, the above operation of the controller 23 will be described with reference to the flowchart of FIG.

First, the controller 23 determines whether or not the transmission is in the neutral state on the basis of the signal f from the neutral sensor 27 in step P ₁ of the flow chart, and when it is not in the neutral state such as when traveling, the controller 23 follows the step P ₂ . Perform normal fuel control. That is, feedback control, open control, or fuel cut control is performed according to the areas B, C, and D shown in FIG. Meanwhile, when the transmission is in the neutral state, and then executes step P _3, whether operating region exceeds the first boundary X of FIG. 4 from the open control region C side feedback control region B side judge. That is, when a so-called racing operation is performed by depressing the accelerator pedal while the transmission is in a neutral state or when a foot pedal operation of the accelerator pedal is performed, if an external load such as a compressor for an air conditioner does not act on the engine 10, The state of the engine 10 changes along the no-load line Z shown in FIG. 4 and changes from the open control area C to the feedback control area B.
However, when an external load is applied in the middle of a racing operation, or when a racing operation is performed while an external load is applied,
The operating state deviates from the no-load line Z to the high load side (low engine speed side) as shown by the arrow (a), and shifts to the feedback control region B. Therefore, when the operation region moves from the open control region C to the feedback control region B over the first boundary line X in this way, the controller 23 executes Step P ₄ and enters the feedback control region B. Nevertheless, the control before crossing the boundary line X, that is, the control for maintaining the fuel injection amount in the open control region C at a constant amount is continuously performed. This prevents a sudden change in the fuel control system, a sharp decrease in the fuel supply amount, or a drop in the engine speed that accompanies this due to a shift in the operating region during a racing operation or the like. The operating state of the engine at the time of transition will be stabilized.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall constitution of the present invention, FIG. 2 is a system diagram showing the constitution of an embodiment of the present invention, FIG. 3 is a flow chart showing the operation of the same embodiment, and FIG. It is an area | region figure which shows the division of the operation area used as object. 10 ... Engine, 23 ... Controller (region determination means, fuel supply control means, correction means), 24 ... Throttle opening sensor, 25 ... Engine speed sensor, 27 ...
... Neutral sensor (neutral detection means).

Claims (1)

[Claims] 1. An engine operating speed signal and a throttle opening signal are defined by defining a boundary line set on the high load side in the vicinity of a no-load operating line to define both operating regions of the engine using the engine speed and the throttle opening as parameters. Region determination means for inputting a degree signal to determine which region the actual engine operating state is defined by the boundary line,
A fuel control device for an engine, comprising: a fuel supply control means for increasing the fuel supply amount when the area determined by the determination means is on the low load side of the boundary line as compared to when the area is on the high load side of the boundary line. There is a neutral detection means for detecting the neutral state of the transmission provided in the power transmission system for transmitting the output of the engine to the drive wheels, and when the neutral state of the transmission is detected by the detection means, by the area determination means Even if the determined operating region is the region on the high load side of the boundary line, the fuel supply control unit is provided with correction means for performing fuel control according to the region on the low load side of the boundary line. Engine fuel control system.