JPH102249A - Method and device for avoiding knocking - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely avoid a knocking by measuring and integrating the time when an engine output exceeds a rated power and, when the integrated value exceeds a limit at which a knocking is expected to occur, by predicting the knocking and controlling a knocking avoiding means. SOLUTION: When a gas engine E is operated to which a generator G of a stationary type and operated at a light load, for example, the generator used in a co-generation system is connected, a control unit C detects an engine output with an engine output detection means A and judges if the detected engine output exceeds a rated power or not. If the answer is YES, the time when the detected engine output exceeds the rated power is measured and integrated. It is judged if the integrated value exceeds the limit at which a knocking is expected to occur or not and, if the answer is YES, the knocking is expected to occur and hence a control signal is output to a knocking avoiding means B to avoid the knocking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for avoiding knocking of an engine (for example, a gas engine to which a generator used in a cogeneration system is connected) which is required to be stationary and operate at a constant load.

[0002]

2. Description of the Related Art In such an engine, conventionally, a knock margin is provided in advance with an output margin of 10 to 15% so that knocking does not occur even if a slight output fluctuation occurs.

[0003]

However, in the case where a knocking margin is provided, the engine is operated by derating the performance of the engine. As a result, the engine becomes larger and the initial cost is increased.

On the other hand, there is a technique for detecting knocking by detecting vibration of the engine by an acceleration sensor and delaying the ignition timing to avoid knocking when knocking is determined.

However, when a knocking detection sensor such as an acceleration sensor is mounted on the engine body, it is necessary to obtain a mounting location for the sensor around the engine, where layout requirements are very strict. There is a problem that the degree of vibration is different due to the above. Special sensors, such as knocking sensors, are relatively expensive and require careful handling.

The present invention has been proposed in view of the above-described problems of the prior art, and it is possible to reliably avoid knocking without providing a knocking margin, and to provide a knock detection sensor mounting location. It is an object of the present invention to provide a knocking avoiding method and an apparatus therefor which can solve the problem and the like.

[0007]

According to the present invention, there is provided a knocking avoiding method, comprising: an engine output detecting step of detecting an output of an engine of a stationary type which requires a constant load operation; An output determination step of determining whether or not the engine output has exceeded the rated output, a time integration step of measuring and integrating the time when the engine output has exceeded the rated output, and occurrence of knocking in the integrated value of the time when the engine output has exceeded the rated output. A limit value determining step of determining whether or not an expected limit value is exceeded; and a knocking avoiding step of predicting knocking when the integrated value exceeds the limit value and controlling knocking avoiding means to avoid knocking. , And

In implementing the knocking avoiding method according to the present invention, it is preferable that the engine output detecting step is performed by detecting an engine throttle opening degree. Detecting exhaust pressure before turbine, detecting intake air temperature,
It is also preferable to detect the output current value of the generator connected to the gas engine of the cogeneration system, to detect the output power value of the generator connected to the gas engine of the cogeneration system, and the like.

Further, when the knocking avoiding method of the present invention is carried out, it is preferable that the knocking avoiding step is performed by retarding the ignition timing. Alternatively, the knocking avoiding step is preferably performed by changing the air-fuel ratio to the lean side. When the engine employs an exhaust gas recirculation (EGR) mechanism, the knocking avoiding step includes an exhaust gas recirculation amount (EGR amount).
This is preferably done by increasing further,
The knocking avoiding step is performed by adding steam to the intake system, lowering the intake air temperature, reducing the compression ratio by a Miller cycle, or lowering the temperature of engine (or engine) cooling water. Is preferred. Here, when the engine cooling water system performs two-system cooling in which the system is separated into a head side and a block side, by lowering the temperature of the head side cooling water,
It is preferable to perform the knocking avoiding step.

[0010] The knocking avoiding device of the present invention comprises an engine output detecting means for detecting the output of an engine of a stationary type and a type requiring a constant load operation, a knocking avoiding means, and the detected engine output having a rated output. Control means for controlling knocking avoidance means to avoid knocking when the integrated value of the time exceeding the time exceeds a limit value at which occurrence of knocking is expected.

In implementing the knocking avoiding device of the present invention, it is preferable that the engine output detecting means is constituted by an engine throttle opening degree detecting means, or that the engine output detecting means is an intake pipe pressure detecting means.
Turbine exhaust pressure detection means before the turbocharger, intake air temperature detection means, output current value detection means of the generator connected to the gas engine of the cogeneration system, or generator connected to the gas engine of the cogeneration system It is preferable that the output power detecting means is constituted by the above-described output power value detecting means.

Further, in the knocking avoiding device of the present invention, it is preferable that the knocking avoiding means is constituted by ignition timing retarding means. Alternatively, it is preferable that the knocking avoiding means is constituted by air-fuel ratio control means for changing the air-fuel ratio to the gas lean side. Further, the engine has an exhaust gas recirculation (EGR) mechanism, and the knocking avoiding means is constituted by an exhaust gas recirculation amount control mechanism.
The exhaust gas recirculation amount (EGR amount) is preferably increased to avoid knocking. A mechanism for adding steam to the intake system of the engine is provided, and the knocking avoiding means is constituted by a mechanism for controlling the amount of steam added. Is preferably configured to avoid knocking by mixing. In addition, the knocking avoiding means is an intake air temperature lowering means,
It is preferable that it is constituted by a low compression ratio means by a Miller cycle or an engine (or engine) cooling water temperature lowering means. Here, the engine cooling water system is 2
In the case of system cooling, it is preferable that the knocking avoiding means is constituted by a means for lowering the temperature of the engine-side cooling water.

According to the present invention having the above-described structure, the control means determines that knocking has occurred when the detected engine output exceeds the rated output and the integrated value of the overrun exceeds the limit value. The knocking is avoided by predicting and controlling the knocking avoiding means.

[0014] As a result, the knocking is reliably avoided, so that it is not necessary to operate with a knocking margin, which contributes to a reduction in initial cost.

Here, the installation of the means for detecting the engine output is not limited to the area around the engine, unlike the knocking sensor or the like. Therefore, the mounting location of the sensor around the engine is very strict in terms of layout. There is no problem of having to get it. Further, the problem of the conventional knocking sensor that the sensitivity differs depending on the sensor mounting location cannot occur.

Further, the engine output detecting means used in the present invention as described above is inexpensive and easy to handle as compared with a knocking sensor. Therefore, it can greatly contribute to reduction of various costs.

[0017]

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

FIG. 1 and FIG. 2 schematically show the present invention, in which a gas engine E to which a generator G used for a cogeneration system, for example, which is required to have a stationary and constant load operation is connected. It is shown. An engine output detecting means A for detecting the engine output and a knocking avoiding means B are provided separately from a main body (not shown) of the gas engine E, and are connected to a control unit C as a control means. .

In operation, as shown in FIG. 3, the control unit C detects the engine output by the engine output detecting means A during the operation of the engine E (step S1) (step S2: output detecting step), and detects the detected engine output. Is higher than the rated output (step S3:
Output determination step).

If NO, the process returns to step S1, and if step S3 is YES, the time during which the detected engine output exceeds the rated output is measured and integrated (step S1).
4: time integration step).

Next, it is determined whether or not the integrated value exceeds a limit value at which knocking is expected to occur (step S5: limit value determination step).

If NO, the process returns to step S1, and YE
If S, knocking is predicted to occur (step S6: knocking prediction step).

Then, a control signal is output to the knocking avoiding means B to activate the knocking avoiding means B, thereby avoiding knocking (step S7: knocking avoiding step). After the step S7 ends, the process returns to the step S1.

FIG. 4 shows an embodiment of the present invention. The gas engine E has an engine output detecting means A
, And an ignition timing retarding means B1 as knocking avoiding means B are connected to the control unit C1.

The engine output detecting means A is not limited to the engine throttle opening detecting means A1.
As shown in the figure, the means A1, the intake pipe pressure detecting means A
2. Turbine exhaust pressure detection means A3, intake air temperature detection means A4, output current value detection means A5 of generator G,
A detection means selected from the output power value detection means A6 of the generator G is used.

Further, the knocking avoiding means B is not limited to the ignition timing retarding means B1, but as shown in FIG.
Means B1, air-fuel ratio control means B2, EGR amount control means B
3. Addition means B4 for adding water vapor to the intake air, intake air temperature lowering means B5 for cooling the intake air temperature, means for lowering the compression ratio using a Miller cycle (low compression ratio means using a Miller cycle) B6, engine cooling water temperature lowering means Means selected from B7 and (when the engine cooling water system is configured to perform two-system cooling) means B8 for lowering the temperature of the engine-side cooling water.

In connection with this, the control unit C includes means A1
A6 and the combination of means B1 to B8.

Next, the control mode of FIG. 4 will be described with reference to FIG. When the engine E is operating (step S10), the control unit C1 detects the engine throttle opening detecting means A1.
(Step S11), and it is determined whether or not the detected throttle opening exceeds the throttle opening indicating the rated output (step S1).
2).

If NO, the process returns to step S10 and Y
If it is ES, the time in which the detected throttle opening exceeds the throttle opening indicating the rated output is measured and integrated (step S13).

Next, it is determined whether or not the integrated value exceeds a limit value at which knocking is expected to occur (step S14). If step S14 is NO, the process returns to step S10, and if YES, it is predicted that knocking will occur (step S15).

If it is predicted that knocking will occur (step S15), a control signal is output to the ignition timing retarding means B1 to retard the ignition timing to avoid knocking (step S16). After a certain period of operation (step S17), the ignition timing is returned to the original (step S1).
8) Return to step S11.

In the above control, when the air-fuel ratio control means B2 is used, the engine is controlled to the lean side to avoid knocking, and the air-fuel ratio is returned to the original value after a certain period of operation.

When the EGR amount control means B3 is used, E
The GR amount is increased to avoid knocking, and the EGR amount is returned to the original value after a certain period of operation.

When the adding means B4 for adding steam to the intake air is used, the steam is supplied to the intake air to avoid knocking, and after a certain period of operation, the supply of the steam is stopped.

When the intake air temperature lowering means B5 is used,
Knocking is avoided by lowering the intake air temperature using the means B5, and after operating for a certain time in that state, the intake air temperature is restored.

When the means B6 for lowering the compression ratio using the Miller cycle is used, knocking is avoided by reducing the compression ratio of the engine, and after a certain period of operation, the compression ratio is restored.

When the engine cooling water temperature lowering means B7 is used, the engine cooling water temperature is lowered by the means B7 to cool the engine and avoid knocking. After operating in this state for a certain period of time, the engine cooling water temperature is returned to the original temperature.
Here, when the engine is a two-system cooling type,
The means B8 lowers the temperature of the engine head side to avoid knocking. After a certain period of operation, the engine head side temperature is returned to the original temperature.

[0038]

Since the present invention is configured as described above, it is not necessary to provide a knocking margin. Therefore, it is not necessary to operate the motor with the rated output of 100 at, for example, 85. As a result, the engine can be made smaller and the initial cost can be reduced.

Since the engine output detecting means does not need to be attached to the engine body, the conventional problem (the problem of the layout around the engine) is solved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing an embodiment of the present invention.

FIG. 2 is a control block diagram of FIG.

FIG. 3 is a control flowchart of FIG. 1;

FIG. 4 is a configuration diagram showing one embodiment of the present invention.

FIG. 5 is a control block diagram of FIG. 4;

FIG. 6 is a control flowchart of FIG. 4;

[Explanation of symbols]

A: Engine output detecting means A1: Engine throttle opening detecting means A2: Intake pipe pressure detecting means A3: Turbine exhaust pressure detecting means before turbocharger A4: Intake air temperature detecting means A5 ... means for detecting the output current value of the generator A6 ... means for detecting the output power value of the generator B ... means for avoiding knocking B1 ... means for retarding the ignition timing B2 ... means for controlling the air-fuel ratio B3 EGR amount control means B4 ... Addition means for adding water vapor to intake air B5 ... Intake air temperature lowering means B6 ... Lower compression ratio using Miller cycle B7 ... Engine cooling water temperature lowering means B8: Head side cooling water temperature lowering means C, C1: Control unit E: Gas engine G: Generator

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display F02B 47/02 F02B 47/02 F02D 19/12 F02D 19/12 A 41/22 305 41/22 305B F02M 25/07 F02M 25/07 A F02P 5/152 F02P 5/15 D 5/153

Claims (30)

[Claims] 1. An engine output detecting step of detecting an output of an engine of a stationary type requiring a constant load operation, and an output determining step of determining whether or not the detected engine output exceeds a rated output. , A time integration process that measures and integrates the time when the engine output exceeds the rated output, and determines whether the integrated value of the time when the engine output exceeds the rated output exceeds a limit value at which knocking is expected to occur. A knocking avoiding step for predicting occurrence of knocking when the integrated value exceeds the limit value, and controlling knocking avoiding means to avoid knocking. . 2. The knocking avoiding method according to claim 1, wherein the engine output detecting step is performed by detecting an engine throttle opening. 3. The knocking avoiding method according to claim 1, wherein the engine output detecting step is performed by detecting a pressure in the intake pipe. 4. The engine output detecting step is performed by detecting a pre-turbine exhaust pressure of a turbocharger.
How to avoid knocking. 5. The knocking avoiding method according to claim 1, wherein the engine output detecting step is performed by detecting an intake air temperature. 6. The knocking avoiding method according to claim 1, wherein the engine output detecting step is performed by detecting an output current value of a generator connected to the gas engine of the cogeneration system. 7. The knocking avoiding method according to claim 1, wherein the engine output detecting step is performed by detecting an output power value of a generator connected to the gas engine of the cogeneration system. 8. The knocking avoiding method according to claim 1, wherein the knocking avoiding step is performed by retarding the ignition timing. 9. The knocking avoiding method according to claim 1, wherein the knocking avoiding step is performed by changing an air-fuel ratio to a lean side. 10. The knocking avoiding method according to claim 1, wherein the engine employs an exhaust gas recirculation mechanism, and the knocking avoiding step is performed by increasing an exhaust gas recirculating amount. 11. The knocking avoiding method according to claim 1, wherein the knocking avoiding step is performed by adding steam to the intake system. 12. The knocking avoiding step is performed by lowering the intake air temperature.
How to avoid term knocking. 13. The knocking avoiding step is performed by setting a low compression ratio by a Miller cycle.
7. The knocking avoidance method according to any one of items 7 to 7. 14. The knocking avoiding method according to claim 1, wherein the knocking avoiding step is performed by lowering a temperature of the engine cooling water. 15. The knocking avoiding method according to claim 14, wherein the knocking avoiding step is performed by lowering the temperature of the cooling water on the head side of the engine performing the two-system cooling. 16. An engine output detecting means for detecting the output of an engine of a stationary type requiring a constant load operation, a knocking avoiding means, and an integrated value of a time when the detected engine output exceeds a rated output. A control means for controlling knocking avoiding means to avoid knocking when knocking exceeds an expected limit value. 17. The knocking avoiding device according to claim 16, wherein the engine output detecting means comprises an engine throttle opening detecting means. 18. The knocking avoiding device according to claim 16, wherein the engine output detecting means comprises an intake pipe pressure detecting means. 19. The engine output detecting means comprises a turbocharger exhaust pressure detecting means in front of a turbocharger.
Knocking avoidance device. 20. The knocking avoiding device according to claim 16, wherein the engine output detecting means comprises an intake air temperature detecting means. 21. The knocking avoiding device according to claim 16, wherein the engine output detecting means comprises output current value detecting means of a generator connected to the gas engine of the cogeneration system. 22. The knocking avoiding device according to claim 16, wherein the engine output detecting means comprises output power value detecting means of a generator connected to the gas engine of the cogeneration system. 23. The knocking avoiding device according to claim 16, wherein the knocking avoiding means comprises ignition timing retarding means. 24. The knocking avoiding device according to claim 16, wherein the knocking avoiding means comprises an air-fuel ratio control means for changing an air-fuel ratio to a gas lean side. 25. The knocking avoiding device according to claim 16, wherein the engine has an exhaust gas recirculation mechanism, and the knocking avoiding means is constituted by an exhaust gas recirculation amount control mechanism. 26. The engine according to claim 16, wherein a mechanism for adding steam to the intake system of the engine is provided, and the knocking avoiding means comprises a mechanism for controlling the amount of steam added.
Knock avoidance device for term. 27. The knocking avoiding device according to claim 16, wherein the knocking avoiding means is constituted by an intake air temperature lowering means. 28. The knocking avoiding device according to claim 16, wherein the knocking avoiding means is constituted by a low compression ratio means using a Miller cycle. 29. The knocking avoiding device according to claim 16, wherein the knocking avoiding means is constituted by engine cooling water temperature lowering means. 30. The knocking avoiding device according to claim 29, wherein the engine cooling water system is configured to perform two-system cooling, and the knocking avoiding means is configured by a means for lowering the temperature of the engine side cooling water.