JPH0243896B2 - - 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, systems in which knocking is suppressed only by correcting the air-fuel ratio toward the rich side tend to waste fuel when severe knocking occurs. There is a problem that fuel economy deteriorates significantly. Further, in the air-fuel ratio control as described above, 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. Furthermore, 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.

As a knocking control method that does not cause such inconvenience, when the occurrence of knocking is detected, a waste gate valve installed in parallel to the turbine section of the exhaust turbocharger is opened, the boost pressure is lowered, and the knocking is suppressed. It is possible to suppress the However, if the occurrence of knocking is suppressed only by controlling the opening of the wastegate valve, the frequency with which the wastegate valve is opened becomes very high, resulting in a decrease in output. Therefore, there is a problem that the existence value of the exhaust turbocharger is diminished.

[Means for solving the problem] In order to solve the problem, the present invention utilizes waste gate valve opening control and an electromagnetic fuel injection pump provided as an alternative element to the mechanical acceleration pump. The air-fuel ratio control is selectively performed depending on the magnitude of knocking to suppress the knocking. That is, in the present invention, when the occurrence of knocking is detected by the knock sensor and the degree of knocking is large, the control means outputs a signal to the wastegate controller indicating that the wastegate valve should be opened. The present invention is characterized in that, when the degree of knocking is small, the control means outputs a signal indicating that fuel should be discharged toward the fuel injection pump.

[Operation] Therefore, when severe knocking occurs, the waste gate valve opens and the supercharging pressure decreases, and the occurrence of knocking is quickly suppressed. On the other hand, when the knocking is mild, fuel is discharged from the fuel injection pump to the intake system passage, the air-fuel ratio is momentarily corrected to the rich side, and the knocking is 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, a command indicating that acceleration fuel should be discharged toward the fuel injection pump 17 is determined. 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 and the degree of knocking is large, a signal c is output to the waste gate controller 16 indicating that the waste gate valve 15 should be opened; When the degree of
and a control means for outputting a signal d indicating that fuel should be discharged toward. In this embodiment, the microcomputer 33 plays the role of 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. That is, the relationship between the knocking intensity and the opening degree (minimum value) of the waste gate valve 15 necessary to suppress the knocking, and the relationship between the knocking intensity and the optimal fuel increase value to suppress the knocking. The relationships are stored in the memory 35 in the form of a map. Then, when the knocking detection signal e is given from the knocking sensor 41,
A comparison is made to see if the strength of the knocking is larger or smaller than a predetermined setting value. If it is determined that the knocking is large, the wastegate valve opening degree corresponding to the knocking strength is selectively retrieved from the memory 35, and an opening command signal c corresponding to the opening degree is directed to the wastegate controller 16. It is configured so that it is output as follows. The waste gate controller 16 duty-controls the waste gate valve 15 and receives the opening command signal c.
The system is designed to ensure a substantial opening corresponding to the required amount of exhaust gas and bypass the required amount of exhaust gas. On the other hand, when it is determined that the knocking strength is smaller than the set value, the fuel increase value corresponding to the knocking strength is selectively retrieved from the memory 35, and the number of pulse signals d corresponding to the fuel increase value is is output 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. If the strength of the knocking is greater than the set value, the microcomputer 33 outputs an opening command signal c to the wastegate controller 16 in accordance with the degree of knocking. 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 quickly suppressed. On the other hand, if the strength of knocking is smaller than the set value, the microcomputer 33 outputs a signal d to the fuel injection pump 17 indicating that fuel should be discharged according to the degree of knocking, and the 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 controlled.

In this way, knocking can be suppressed.
The opening control of No. 5 and the air-fuel ratio control are selectively used. That is, large knocking is suppressed by controlling the opening of the waste gate valve 15, and relatively small knocking is suppressed by controlling the air-fuel ratio. Therefore, the occurrence of knocking can be quickly brought under control while minimizing the inconvenience that fuel is wasted to suppress knocking.

In addition, this problem is suppressed by air-fuel ratio control, except for large knocking that is difficult to suppress quickly, so waste gate valve 1
5 does not occur frequently. Therefore, unlike the case where knocking is suppressed only by controlling the opening of the waste gate valve, there is no problem in that the engine output is greatly reduced.

In addition, air-fuel ratio control for suppressing small knocking that does not require opening the waste gate valve 15 is performed using the electromagnetic fuel injection pump 33 provided as an alternative element to the acceleration pump. Control with higher responsiveness is possible than with systems that correct the air-fuel ratio by adjusting the air bleed or main jet opening. Moreover, 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 knotting 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 of any intensity. Furthermore, it is possible to provide a knocking control device that can effectively prevent wasteful use of fuel and decrease in output.

[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 passage, 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 and the degree of knocking is large, a signal is output to the wastegate controller indicating that the wastegate valve should be opened, while when the degree of knocking is small, a signal is sent to the fuel injection pump. 1. A knocking control device comprising: control means for outputting a signal indicating that fuel should be discharged.