JPH0243897B2 - - 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, the air-fuel ratio is corrected to the rich side. Note that conventional air-fuel ratio control is performed by changing the opening degree of the air bleed passage or the main jet.

[Problems to be Solved by the Invention] However, a system in which knocking is suppressed only by correcting the air-fuel ratio to the rich side tends to waste fuel, resulting in poor fuel economy. There is a problem with doing so. 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. moreover,
Such air-fuel ratio control also has the problem that a time delay tends to occur in increasing the amount of fuel, and that it is difficult to perform accurate control with high responsiveness.

[Means for Solving the Problem] In order to solve this problem, the present invention suppresses the occurrence of knocking by controlling the opening of the waste gate valve preferentially in a partial area. The air-fuel ratio is changed by using an electromagnetic fuel injection pump, which is provided as an alternative element to the mechanical acceleration pump, only when knocking cannot be suppressed by control. That is, in the present invention, when the knock sensor detects the occurrence of knocking, the control means outputs a signal indicating that the waste gate valve should be opened, and the waste gate valve is opened to a preset partial opening degree. The present invention is characterized in that the fuel injection pump is configured to output a signal indicating that fuel should be discharged toward the fuel injection pump when the occurrence of knocking cannot be suppressed completely.

[Effect] Therefore, when knotting occurs,
First, the wastegate valve opens slightly to lower the boost pressure and suppress the occurrence of knocking. Note that if a strong knocking occurs that cannot be suppressed even if the waste gate valve is opened to the set opening degree, then fuel will be discharged from the fuel injection pump to the intake system path. As a result, the air-fuel ratio is instantaneously corrected to the rich side, and knocking is quickly suppressed.

[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 combustion chamber 5 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 depending on the amount of depression of the accelerator pedal, while the throttle valve 8 of the secondary system 6b It is connected to a diaphragm mechanism 9 that is activated by the pressure within the intake system passage 2, and is designed to open mainly in a 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), etc., and this exhaust system path 3 and the intake air Exhaust turbocharger 1 is connected between system line 2
2 are provided. The exhaust turbocharger 12 is
a compressor section 13 interposed in a portion of the intake system path 2 upstream of the carburetor 6; and the exhaust system path 3.
a turbine section 14 that is interposed in the middle and rotates by exhaust energy to drive the compressor section 13;
A waste gate valve 15 is provided in parallel to the turbine section 14. 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 throttle valve 7 is opened at an acceleration of a certain level or more, an instruction is sent to the effect that acceleration fuel should be discharged toward the fuel injection pump 17. Outputs signal b. Specifically, a pulse voltage is applied to the solenoid 23 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 a knock sensor 4 for detecting knocking.
1, when the occurrence of knocking is detected by the knock sensor 41, it first outputs a signal c to the waste gate controller 16 indicating that the waste gate valve 15 should be opened, and also causes the waste gate valve 15 to open in the intermediate position. and control means for outputting a signal d indicating that fuel should be discharged toward the fuel injection pump 17 when the occurrence of knocking cannot be suppressed even if the opening is opened to a set opening degree. And in this example,
The microcomputer 33 serves as the control means. To be more specific, the knock sensor 41 converts the vibration of the cylinder block 42, which is excited by air column vibration due to knocking, into an electric signal e using a piezoelectric element, and converts the electric signal e into the electric signal e. The information is input to an interface 36 of a microcomputer 33. In addition to the above-mentioned programs, the microcomputer 33 includes the following programs and data.
In other words, the strength of knocking and the waste gate valve 15 necessary to suppress the knocking.
The relationship between the opening degree (minimum value) and the opening degree (minimum value) is stored in the memory 35. When a knocking detection signal e is given from the knock sensor 41, the wastegate valve opening degree corresponding to the knocking intensity is selectively retrieved from the memory 35, and an opening command signal c corresponding to the opening degree is sent to the wastegate valve. The signal is output to the controller 16. The wastegate controller 16 controls the duty of the wastegate valve 15 to ensure a substantial opening corresponding to the opening command signal c, thereby bypassing a required amount of exhaust gas. Furthermore, the relationship between the knocking strength in the state where the waste gate valve 15 is controlled to open and the optimal fuel increase value for suppressing the knocking is determined through experiments, and the data is stored in the memory 35. be. If the knock sensor 41 continues to supply the signal e even when the waste gate valve 15 is opened to a set opening between fully closed and fully open, the fuel increase value corresponding to the knocking intensity is determined. The pulse signals d are selectively retrieved from the memory 35 and the number of pulse signals d corresponding to the fuel increase value is outputted from the interface 37 to the fuel injection pump 17.

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 d to that effect is provided from the knock sensor 41 to the microcomputer 33. As a result, the opening command signal c corresponding to the degree of knocking is sent from the microcomputer 33 to the wastegate controller 16.
output towards. As a result, the waste gate valve 15 is opened to the actual opening degree corresponding to the signal c, a part 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.
Note that if the occurrence of knocking cannot be suppressed even when the waste gate valve 15 is opened to the set opening degree, the microcomputer 33 further sends a signal from the microcomputer 33 to the fuel injection pump 17 according to the degree of knocking. A signal d indicating that fuel should be discharged is output, and the fuel injection pump 17 operates a number of times corresponding to the signal d to discharge fuel into the intake passage 32. Therefore, the air-fuel ratio is instantaneously corrected to the rich side, and knocking is quickly suppressed. By the way, if knocking is not brought under control even after such air-fuel ratio control is added, the waste gate valve 15 gradually opens and finally becomes fully open.

In this way, knocking can be suppressed, and in principle, knocking is suppressed by controlling the opening of the waste gate valve 15. That is, the air-fuel ratio is controlled only when knocking cannot be suppressed even if the waste gate valve 15 is opened to the set opening degree. Therefore, it is possible to minimize the inconvenience that fuel is wasted to suppress knot king.
Fuel economy can be significantly improved compared to systems that mainly rely on air-fuel ratio control.

Note that since air-fuel ratio control is performed when the wastegate valve 15 is opened to the partially set opening degree, the engine output will be significantly reduced as in the case where knocking is suppressed only by the wastegate valve. This inconvenience does not occur.

In addition, the waste gate valve 15 is controlled preferentially, and the electromagnetic fuel injection pump 33 provided as an alternative element to the acceleration pump is used to correct the air-fuel ratio when knocking occurs. Compared to systems that correct the air-fuel ratio by adjusting the air bleed or main jet opening, it is possible to perform control with higher responsiveness, and knocking can be suppressed quickly and accurately. Further, when the functions of the existing waste gate valve 15 and acceleration fuel injection pump 17 are utilized in this way, there is no need for any special actuator, valve, etc. for knocking control. In particular, this embodiment can be implemented simply by adding the knock sensor 41 and expanding the program in the microcomputer 33. Therefore, it has the advantage that the number of parts is small, the structure is simple, and it can be easily implemented.

In the above embodiment, a case has been described in which the microcomputer for accelerating fuel increase control also plays a role as a control means for knocking control, but the present invention is not necessarily limited to such a device. For example, a control means for increasing the amount of acceleration fuel and a control means for knocking control may be provided separately.

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,
A formula showing the relationship between the degree of knocking and the amount of fuel discharged and the opening degree of the wastegate valve is stored in memory, and the formula is used to calculate the optimal amount of fuel discharged and the opening degree of the wastegate valve each time. Good too.

[Effects of the Invention] Since the present invention has the above configuration, it has a small number of parts, a simple structure, and is easy to implement.Moreover, it has high responsiveness and can quickly and accurately suppress knocking. Furthermore, the present invention provides a knocking control device that can prevent wasteful use of fuel and ensure high fuel economy.

[Brief explanation of drawings]

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... carburetor, 12...
...Exhaust turbo charger, 15...Wastegate valve, 16...Wastegate controller, 17...Fuel injection pump, 33...Control means (microcomputer).

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. This knocking control device for an engine is equipped with an exhaust turbo charger in which a wastegate valve is arranged in parallel, and a wastegate controller that opens and closes the wastegate valve. When the occurrence of knocking is detected, it first outputs a signal to the wastegate controller indicating that the wastegate valve should be opened, and also prevents knocking from occurring even if the wastegate valve is opened to an intermediate setting. A knocking control device comprising: control means for outputting a signal indicating that fuel should be discharged to the fuel injection pump when the knocking cannot be suppressed completely.