JPH0251064B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a knocking control device mainly applied to an automobile engine.

[Prior Art] Many modern automobile engines are equipped with a supercharger such as an exhaust turbocharger or have a higher compression ratio in order to achieve higher efficiency. It is more likely to occur. Knocking is air column vibration that occurs due to self-ignition of end gas in the combustion chamber, and it not only produces unpleasant sounds and vibrations, but may also be accompanied by a reduction in output. If excessive knocking occurs frequently, there is a risk that the spark plug, valve, or piston may be damaged by melting, resulting in a disadvantage that the durability of the engine is significantly reduced. Therefore, this type of engine is generally equipped with a knocking control device to suppress the occurrence of harmful knocking.

As a prior art related to this type of knocking control device, there is one disclosed in Japanese Patent Application Laid-Open No. 138435/1983. That is, in this engine, a knock sensor for detecting knocking is provided in the engine body, and when the knocking sensor detects the occurrence of knocking, at least one of the air-fuel ratio or the ignition timing is corrected. Note that conventional air-fuel ratio control is performed by changing the opening degree of the air bleed passage or the main jet. Furthermore, the ignition timing control is such that the ignition timing is continuously changed depending on the intensity of knocking.

[Problems to be Solved by the Invention] However, in order to continuously change the ignition timing and perform fine knocking suppression control, it is necessary to adopt a so-called full-torque ignition system, which is expensive and difficult to implement. This is often accompanied by difficulties.
Further, when the air-fuel ratio is corrected by changing the opening degree of the air bleed passage or the main jet, a special actuator is required to adjust the opening degree. Therefore, there are problems in that the number of parts increases, the structure becomes complicated, and costs increase. Further, in such air-fuel ratio control, there is a problem that a time delay tends to occur in increasing the amount of fuel, and it is difficult to perform accurate control with high responsiveness.

[Means for solving the problem] In order to solve the problem, the present invention provides rough control of ignition timing and uses an electromagnetic fuel injection pump provided as an alternative element to the mechanical acceleration pump. The occurrence of knocking can be precisely suppressed by controlling the air-fuel ratio and controlling the opening of the waste gate valve. That is, the present invention provides an ignition timing correction mechanism that retards the ignition timing by a certain value when a retard command signal is input, and when the knock sensor detects the occurrence of knocking,
The fuel discharge command means outputs a signal to the effect that fuel should be discharged toward the fuel injection pump, and if knocking cannot be suppressed even after the signal is output, the waste gate opening command means outputs a signal to the waste gate controller. A signal for opening the gate valve is output, and when knocking cannot be suppressed even after the signal is output, a retard command signal is output from the retard command means to an ignition timing correction mechanism. Features.

[Operation] When knocking occurs, first, a signal to the effect that fuel should be discharged from the mechanical discharge command means to the fuel injection pump is output, and a predetermined amount of fuel is injected from the fuel injection pump into the intake air. It is discharged into the system, and the air-fuel ratio is momentarily corrected to the rich side.
If knocking still cannot be suppressed, then the wastegate opening command means outputs a signal to the wastegate controller to open the wastegate valve, the wastegate valve is opened, and the supercharging pressure is reduced. . If knocking still does not subside even after taking such measures, a retard command signal is further output from the retard command means to the ignition timing correction mechanism, and the ignition timing is corrected to the retard side by a certain value. .

As described above, according to the present invention, control by the fuel discharge command means and wastegate opening command means is sequentially executed depending on the degree of knocking, and only when knocking cannot be suppressed even then, control by the retard command means is performed. Therefore, even if the ignition timing is roughly controlled such as ON or OFF,
The combination of these controls makes it possible to perform fine-grained knocking suppression control as a whole. In other words, depending on the degree of notsking,
A lag occurs in the execution progress of each of the above-mentioned controls, and it becomes possible to perform appropriate control with no excess or deficiency as a whole. Furthermore, if you do this, the frequency of controlling the ignition timing will be reduced, so you will have more opportunities to keep the ignition timing close to the optimum ignition timing, and only the ignition timing will be controlled continuously. Compared to the case where knocking is suppressed through control, it is easier to improve fuel economy.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a system explanatory diagram schematically showing an automobile gasoline engine, in which 1 is the engine body, 2 is an intake system path, and 3 is an exhaust system path. The intake system passage 2 has a starting end open to the atmosphere via an air cleaner (not shown), and a terminal end communicating with the machine room 55 of the engine body 1 via an intake valve 4, with a carburetor 6 intervening in the middle. It has been set up. The carburetor 6 has a first system 6a and a secondary system 6b.
The throttle valve 7 of the first system 6a opens and closes according to the amount of depression of the accelerator pedal, while the throttle valve 8 of the secondary system 6b is a diaphragm mechanism operated by the pressure in the intake system passage 2. 9, and is designed to open mainly in the high load range. The exhaust system path 3 has a starting end communicating with the combustion chamber 5 via an exhaust valve 11 and a terminal end opening to the atmosphere through a muffler (not shown) or the like.
An exhaust turbocharger 12 is provided between the intake system passage 2 and the intake system passage 2. Exhaust turbo charger 12
A compressor section 13 is provided in a portion of the intake system path 2 upstream of the carburetor 6, and a turbine is provided in the middle of the exhaust system path 3 and rotates by exhaust energy to drive the compressor section 13. 14, the turbine section 1
4, a waste gate valve 15 is arranged in parallel. The wastegate valve 15 is for bypassing exhaust gas to decelerate the turbine section 14, and energizes a wastegate controller 16 that operates in response to an electrical signal input from a boost pressure sensor (not shown) or the like. It has been designed to open and close.

Note that the carburetor 6 does not have a mechanical acceleration pump, but is equipped with an electromagnetic fuel injection pump 17 as an alternative element. Fuel injection pump 17
As shown in FIG. 2, a piston 21 is housed in a cylinder 19 that forms a pump chamber 18, and the piston 21 is moved forward and backward by the urging force of a spring 22 and the electromagnetic attraction force of a solenoid 23 to operate the pump. It is configured so that it can perform its functions. The pump 17 also includes an inlet 24 and an outlet 25 that communicate with the pump chamber 18, respectively.
The inlet 24 is connected to the float chamber 28 of the carburetor 6 through an inlet passage 27 having a check valve 26, and the outlet 25 is connected to the intake air of the carburetor 6 through an outlet passage 31 having a check valve 29. It opens into the passage 32. This fuel injection pump 17 is controlled by a microcomputer 33. The microcomputer 33 includes a central processing unit 34 and a memory 35.
and interfaces 36 and 37, and a detection signal from an opening detector 38 for detecting the open position of the throttle valve 7 is inputted to the interface 36. ing. And this microcomputer 33
The following programs are built into the memory 35 of the computer. That is, the detection signal a from the opening detector 38 is sequentially read and the read position information of the throttle valve 7 is second-order differentiated with respect to time to calculate the acceleration of the throttle valve 7 in the opening direction. Then, by comparing the calculated value with a set value, if it is determined that the slot valve 7 is opened with an acceleration above a certain level, a signal b is sent to the fuel injection pump 17 to the effect that acceleration fuel should be discharged. Output. Specifically, a pulse voltage is applied to the solenoid of the fuel injection pump 17 a predetermined number of times.

An engine having such a configuration is provided with a knocking control device according to the present invention. This knocking control device includes an ignition timing correction mechanism 40 that retards the ignition timing by a certain value when a retard command signal f is input, and a knock sensor 41 that detects knocking.
When the occurrence of knocking is detected by the knock sensor 41, the fuel injection pump 1 is first
a fuel discharge command means for outputting a signal d indicating that fuel should be discharged toward the waste gate valve controller 16 when the occurrence of knocking cannot be controlled by this means; The wastegate is provided with a wastegate opening command means for outputting a signal c indicating that the wastegate should be opened, and a retardation command means to be described later. In this embodiment, the microcomputer 33 includes the fuel discharge command means, the wastegate opening command means,
It also plays a role as a retard command means. Specifically, the ignition timing correction mechanism 40 is configured to change the position of a breaker plate (not shown) of the distributor 43 by a vacuum controller 44 operated by intake pipe negative pressure. The configuration is such that the ignition timing can be retarded by a certain value (for example, 5 degrees) only when the angle command signal f is input. The knock sensor 41 uses a piezoelectric element to convert the vibration of the cylinder block 42 excited by the air column vibration of knocking into an electric signal e, and the electric signal e is sent to the interface of the microcomputer 33. I am trying to input it to the face 36. And this microcomputer 33
In addition to the programs mentioned above, the following programs and data are included. That is, the relationship between the degree of knocking and the optimal fuel increase value for suppressing the knocking is determined through experiments and the like, and the data is stored in the memory 35. Then, when the occurrence of knocking is confirmed by the signal e inputted from the knock sensor 41 and the intensity of the knocking is detected, a fuel increase value corresponding to the knocking intensity is selectively retrieved from the memory 35; A number of pulse signals d corresponding to the fuel increase value are output from the interface 37 to the fuel injection pump 17. Further, the memory 35 stores the relationship between the knocking intensity and the opening degree (minimum value) of the waste gate valve 15 necessary to suppress the knocking. If the knocking detection signal e from the knock sensor 41 continues to be input even if the fuel increase value commanded to the fuel injection pump 17 reaches a preset maximum value, the waste gate valve is opened according to the knocking intensity. The opening degree is selectively retrieved from the memory 35, and an opening command signal c corresponding to the opening degree is outputted to the wastegate controller 16. Waste gate controller 1
Reference numeral 6 controls the duty of the waste gate valve 15 to ensure a substantial opening corresponding to the opening command signal c, thereby bypassing a required amount of exhaust gas. Further, even if the air-fuel ratio control and the opening control of the waste gate valve 15 have reached a predetermined limit, if the knocking detection signal e continues to be supplied from the knocking sensor 41,
A retard command signal f is output from the retard command means to the ignition timing correction mechanism 40.

With such a configuration, when the throttle valve 7 is opened at a constant acceleration, a number of pulse voltages corresponding to the degree of acceleration are applied to the solenoid 23 of the fuel injection pump 17, and the pulse voltage is applied to the solenoid 23 of the fuel injection pump 17. The piston 21 reciprocates a number of times corresponding to the number, and the necessary fuel is discharged into the intake passage 32 of the carburetor 6. As a result, the main jet (not shown)
This compensates for the fuel lag from the start and provides appropriate acceleration. Further, when knocking occurs, a signal e to that effect is provided from the knock sensor 41 to the microcomputer 33. As a result, the microcomputer 33 outputs a signal d indicating that fuel should be discharged in accordance with the degree of knocking, and the fuel injection pump 17 operates a number of times corresponding to the signal d to pump fuel into the intake passage 3. Discharge into. Therefore, the air-fuel ratio is instantaneously corrected to the rich side, and knocking is suppressed. Note that if the occurrence of knocking cannot be suppressed by such air-fuel ratio control alone, the opening command signal c is outputted from the microcomputer 33 to the wastegate controller 16. the result,
The waste gate valve 15 is opened to a substantial opening degree corresponding to the signal c, and a portion of the exhaust gas is bypassed, and the turbine section 14 is decelerated. Therefore, the boost pressure is reduced and the occurrence of knocking is suppressed. However, even if such opening control of the waste gate valve 15 is added, if knocking cannot be sufficiently controlled,
A retard command signal f is output from the microcomputer 33 to the vacuum controller 16. As a result, the ignition timing is delayed by a predetermined angle, and the occurrence of knocking is brought under control.

In this way, knocking can be suppressed, and in addition to air-fuel ratio control and wastegate valve opening control, ignition timing is retarded. Therefore, even if the ignition timing is controlled simply by ON and OFF as described above, conditions for suppressing knocking can be precisely created. Moreover, the air-fuel ratio control and supercharging pressure reduction control described above can be performed using the existing fuel injection pump 17 and wastegate controller 1.
6, no special actuators or valves are required. Therefore, this type of engine has a simpler structure and can reduce costs than one that performs fine control over knocking by continuously changing the ignition timing. In other words, sophisticated knocking suppression control can be performed without requiring delicate control of ignition timing, which increases the cost of the ignition system. Additionally, in this way, the ignition timing can be kept relatively close to the optimum ignition timing, which improves fuel economy compared to a method that attempts to suppress knocking only by controlling the ignition timing. There is also the effect that it can be improved.

In addition, if you control the air-fuel ratio and then switch to wastegate valve opening control when the control reaches its limit, the output will decrease by controlling the wastegate valve opening primarily to suppress knocking. Therefore, the power-up function of the exhaust turbocharger 12 can be effectively demonstrated.

In the above embodiment, a case has been described in which the microcomputer for accelerating fuel increase control also functions as a fuel discharge command means for knocking control, a wastegate opening command means, and a retardation command means. , the present invention is not necessarily limited to such things,
For example, a control means for increasing the amount of acceleration fuel, a fuel discharge command means for knocking control, a wastegate opening command means, and a retardation command means may be separately provided.

In addition, the method of determining the fuel discharge amount and the opening degree of the waste gate valve depending on the degree of knotting is as follows.
The method is not limited to the map method described above. for example,
Even if a formula showing the relationship between the degree of knocking and the amount of fuel discharged or the opening of the wastegate valve is stored in memory, the optimal amount of fuel discharged or the valve opening can be calculated each time using the formula. good.

[Effects of the Invention] Since the present invention has the above-described configuration, even if the ignition timing is controlled simply by turning ON and OFF, conditions for controlling knocking can be precisely created. The structure can be simplified compared to one in which knocking is suppressed by continuously changing the ignition timing. Moreover,
In this way, the ignition timing can be kept relatively close to the optimum ignition timing, so combustion efficiency can be improved compared to suppressing knocking only by controlling the ignition timing. Therefore, according to the present invention, knocking can be effectively suppressed without reducing fuel economy or increasing the cost of the ignition system.

Further, in the present invention, first, air-fuel ratio control is performed,
Since the control moves to the opening control of the waste gate valve when the control reaches its limit, there is no inconvenience caused by a drop in output, unlike when knocking is suppressed mainly by controlling the opening of the waste gate valve. Another advantage is that the power-up function of the exhaust turbocharger can be effectively utilized.

[Brief explanation of the drawing]

FIG. 1 is a system explanatory diagram showing one embodiment of the present invention, and FIG. 2 is a schematic sectional view of a fuel injection pump in the same embodiment. 1...Engine body, 2...Intake system path, 3...
Exhaust system path, 5... combustion chamber, 6... vaporization chamber, 12...
...Exhaust turbo charger, 15...Wastegate valve, 16...Wastegate controller, 17...Combustion injection pump, 33...Control means (microcomputer), 40...Ignition timing correction mechanism.

Claims (1)

[Claims] 1. A carburetor that eliminates the mechanical acceleration pump, an electromagnetic fuel injection pump provided as a replacement element for the acceleration pump, and a compressor section disposed upstream of the carburetor and a turbine that drives the compressor section. A knocking control device applied to an engine comprising an exhaust turbocharger in which a wastegate valve is arranged in parallel, and a wastegate controller that opens and closes the wastegate valve, and when a retardation command signal is input. includes an ignition timing correction mechanism that retards the ignition timing by a certain value, a knock sensor that detects knocking, and a knock sensor that sends a signal to the fuel injection pump to discharge fuel when the knocking is detected. a fuel discharge command means for outputting a fuel discharge command; and a waste gate opening command means for outputting a signal to the waste gate controller to open a waste gate valve when knocking cannot be suppressed even if a signal to the effect that fuel should be discharged is output. and retard command means for outputting a retard command signal to the ignition timing correction mechanism when knocking cannot be suppressed even if a signal to open the waste gate valve is output. Knocking control device.