JP2003254144A - Overspeed limit device for gas engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent overspeed of a gas engine without deteriorating drivability. <P>SOLUTION: This device is provided with a throttle valve 26A installed in a suction air passage 22 of the gas engine 2 and working with an accelerator pedal 63, an actuator 64 connected to the throttle valve 26A, an engine speed detecting means 3, a control means 50 controlling operation of the actuator 64. When it is detected that speed of the gas engine 2 exceeds a designated speed, operation of the actuator 64 is restricted by the control means 50 to reduce suction air quantity. <P>COPYRIGHT: (C)2003,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to compressed natural gas (C)
NG) or other gas as fuel,
The present invention relates to a rotation prevention device. [0002] 2. Description of the Related Art Conventionally, Otto cycle engines
(General 4-cycle engine)
As a method to prevent overrun, the engine rotation
When the number of revolutions reaches the upper limit of the allowable number of revolutions, a fuel cut is performed.
Such control is performed. For such a fuel cut
In preventing overrun, the allowable engine speed is
Effective when the rotational speed is sufficiently higher than the normal rotational speed
It is. [0003] In a diesel engine, normal operation is performed.
In the rolling, the intake air amount is almost constant and the accelerator pedal
Output control by determining the fuel injection amount according to the depression amount
Fuel injection even when the engine overspeeds.
The output is reduced by reducing the amount of
Rotation (overrun) is prevented (prior art 1). Ma
Patent Document 1 discloses that the rotation of a gaseous fuel engine is restricted.
Technology, a sub-slot is connected in series with the main throttle valve.
A throttle valve to control the opening of this sub-throttle valve.
This reduces the intake air flow and reduces the engine output
Such a technique is disclosed (Prior Art 2). FIG. 12 is a schematic diagram showing the configuration.
The engine speed is determined by the engine speed detector.
It is detected that the rotation speed (for example, the allowable rotation speed) has been exceeded.
The sub throttle valve control means
Actuation of drive means such as an actuator connected to the tor valve
Is controlled to narrow the intake passage.
You. [0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 7-119527 [0006] The compressed natural gas
Relatively large displacement using gaseous fuel such as
For example, a gas engine (such as 4 liters or more)
The engine is also an Otto cycle engine.)
Generally, as shown in FIG. 11, the normal rotation range and the maximum allowable rotation
Operation near the maximum permissible speed
Relatively many. In such a gas engine, the engine
When the rotation speed reaches the upper limit of the allowable rotation speed,
(A) As shown in FIG.
And the fuel cut, the engine speed at this time
Normal rotation range (normal engine rotation range)
Therefore, as shown in FIG.
That driving performance deteriorates
There is. [0007] The diesel engine also has a normal rotation range.
The difference from the maximum allowable speed is small, but the fuel injection amount is reduced.
The engine output itself is suppressed by
Hunting and other phenomena do not occur. In contrast
In the Otto cycle engine, change the intake air volume
Changes the engine output,
During rotation, output is smooth even if only the fuel injection amount is changed
Can not be suppressed, the engine speed hunting
It will do. [0008] In the technology disclosed in Patent Document 1,
A main throttle valve and a sub throttle valve in the intake passage
Two valve mechanisms must be provided in series.
Roads, especially near the throttle, become larger, increasing costs.
There is a problem of inviting. Also, the area near the throttle is large
, Space efficiency is degraded, and the
There was a problem that was not. [0009] The present invention has been made in view of such problems.
Without deteriorating drivability.
To prevent over-rotation of the engine.
The purpose is to provide an over-rotation prevention device,
This may increase the size and cost of the intake passage near the throttle.
Gas engine to prevent overspeed
To provide an engine overspeed prevention device.
ing. [0010] SUMMARY OF THE INVENTION Therefore, the gas of the present invention
The engine overspeed prevention device is used for the gas engine intake passage.
A throttle valve interposed with the accelerator pedal,
An actuator connected to the throttle valve;
Engine speed detecting means for detecting the engine speed
And the detected information from the engine speed detecting means.
Control means for controlling the operation of the actuator.
The gas engine is detected by the engine speed detecting means.
When it is detected that the rotation speed exceeds a predetermined rotation speed, the control is performed.
The operation of the actuator is controlled by control means and
Characterized in that it is configured to reduce the amount of air
are doing. [0011] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
Explains the gas engine overspeed prevention device as a form
I will tell. (A) Description of the first embodiment First, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic diagram showing the overall configuration, and FIG.
Is a map for explaining the air-fuel ratio control characteristics,
FIG. 3 is a diagram for explaining the operation. Here, the engine 2 is an Otto cycle
An engine, four cycles that explode once in four strokes
Engine. In this embodiment,
Engine 2 is a gas engine using gas as fuel
In particular, here, compressed natural gas (CNG) is used.
It is configured as a CNG engine. Compressed natural gas
Is stored in the fuel tank under high pressure
The high-pressure gas in the fuel tank is
Combustion of the engine 2 through the intake passage 22 of the engine 2
It is supplied indoors. And the combustion chamber
The fuel supplied to the fuel cell is ignited by a spark plug 21 and
Is discharged to the rear exhaust passage 23. By the way, the above-mentioned fuel supply path 10 has
The fuel pressure regulator 16 and the fuel supply amount control device
(Gas valve) 18 is interposed. Fuel
The pressure regulator 16 has a high pressure gas in the fuel tank.
There is a built-in residual pressure sensor 16A for detecting the residual pressure.
The gas valve 18 has a built-in gas temperature sensor 18A.
Have been. The high-pressure gas in the fuel tank is
Adjusted to a predetermined pressure by the fuel pressure regulator 16
Thereafter, a predetermined amount is supplied at a predetermined timing through the gas valve 18.
Is injected into the intake passage 22 from the gas injection nozzle 20 only.
It has become so. On the other hand, in the above-described intake passage 22,
In addition to the gas injection nozzle 20, an air cleaner 27, air
Flow sensor 24, main throttle 26 and idle
Idle speed control as rotation state change adjustment means
A roll valve (ISCV) 28 and the like are provided. The air flow sensor 24 detects the inhaled air
In this case, the amount of gas generated in the intake passage 22 is detected.
The intake flow rate is measured by detecting the number of swirling Karman vortices.
A Karman vortex airflow sensor is used. Ma
The main throttle 26 has a slot (not shown).
A torque position sensor (TPS) is provided.
Of the throttle valve 26A is detected by the TPS
It is supposed to be. Also, the idle speed control valve
(ISCV) 28, the driver can use the accelerator pedal
When releasing the foot and fully closing the throttle valve 26A
In addition, stable idle operation by preventing engine stall
Is provided to enable the
By controlling the open / close state of the ISCV 28, the slot
Adjust the amount of intake air that bypasses the torval valve 26A.
It has become. The ISCV 28 is a predetermined type here.
Step motor that rotates in steps
The open / closed state of the ISCV 28 will be described later.
Based on a control signal from a controller (control means) 50
And is controlled. Reference numeral 30 is
Lean operation (engine with an air-fuel mixture leaner than the stoichiometric air-fuel ratio)
Control of air-fuel ratio during gin operation)
Control valve (air control valve or ACV)
You. This ACV 30 is a throttle valve 26
A is provided in a bypass passage 22A branched from the upstream side of A.
And the intake air volume secured by the above-mentioned ISCV 28
It is provided to take in a larger amount of air.
The ACV 30 is configured as, for example, a diaphragm-type on-off valve.
At a predetermined location where the negative pressure of the engine 2 acts.
It is connected via an ACV solenoid 30A. Soshi
To control the duty of the ACV solenoid 30A.
As a result, the opening control of the ACV 30 is performed.
Has become. The exhaust passage 23 of the engine 2
A controller that detects the air-fuel ratio from the oxygen concentration in the gas
A linear A / F sensor 13 that feeds back to 50,
Exhaust gas temperature sensor 15 for detecting exhaust gas temperature in catalyst 25, etc.
Is provided. The exhaust passage 23 has an exhaust
A brake valve 17 is also provided so that the driver can
When a deceleration operation such as
The exhaust passage 23 is narrowed. Further, this engine 2 is not shown.
However, the fuel gas leaked from the cylinder head etc.
PCV (positive clutch)
NkCase Ventilation = Positive Crankcase Ven
(tilation) valve is also provided. Well, then this
The main part of the present invention in the first embodiment will be described.
The engine 2 detects the engine speed.
A gin speed sensor (engine speed detecting means) 3 is provided.
Have been. This engine speed sensor 3 is a control means.
Connected to the controller 50 as
Information from the engine speed sensor 3
Control the air-fuel ratio (A / F) of the engine 2 based on
As a result, overrun of the engine 2 is prevented.
ing. Specifically, the engine speed sensor 3
The rotation speed Ne of the engine 2 is thereby increased by a predetermined rotation speed (here,
Indicates that the maximum output rotation speed of the engine 2) N1 has been reached.
Is detected, the controller 50 reduces the air-fuel ratio.
It is controlled to the thin side. For this reason,
The controller 50 has a map as shown in FIG.
Is stored. FIG. 2A shows the engine speed Ne.
Map for setting the excess air ratio according to the engine load
And an air-fuel ratio setting map) in which the engine speed Ne
Gradually exceeds the maximum output rotation speed N1.
λ is set to be large. It should be noted that the excess air ratio refers to the stoichiometric air-fuel ratio.
Is the ratio of the actual air-fuel ratio
The stoichiometric air-fuel ratio is calculated as the stoichiometric air-fuel ratio (for CNG engines,
Stoichiometric air-fuel ratio = about 16.8). And book
In the case of the embodiment, as shown in FIG.
From the power generation speed (predetermined speed) N1 to the permissible speed Nmax
The rotation range up to is divided into 4 stages, and according to each rotation range
Thus, the excess air ratio λ is set. That is, in the map shown in FIG.
If the engine speed Ne is less than the maximum output generating speed N1
Is set to λ = 1.0, and the engine is
Operation 2 is performed. Also, the maximum engine speed
The rotational speed from the force generating rotational speed N1 to a rotational speed higher than this rotational speed N1
When it is between N2, set the excess air ratio λ = 1.2
In this case, the air-fuel ratio A / F
The operation of the engine 2 is performed at = 16.8 × 1.2. Similarly, the engine speed is increased from the engine speed N2.
When the rotation speed is between N3 and N3
Is the excess air ratio λ = 1.3 (air-fuel ratio A / F = 16.8 ×
1.3) is set to
Between the rotation speed N3 and the permissible rotation speed Nmax
At some point, the excess air ratio λ = 1.4 (air-fuel ratio A / F =
16.8 × 1.4). Also, when the engine speed is equal to the allowable speed Nmax
Is set to stop the fuel supply if
Have been. And, as described above, the rotation speed of the engine 2
Exceeds the maximum output generating speed N1, the air-fuel ratio A /
By gradually decreasing F, the engine 2
Power to suppress the increase in the rotational speed of the engine 2,
To prevent baluns (overspeed)
You. The control of the air-fuel ratio here is based on the fuel injection amount and intake air
To be performed by controlling both the amount and
You. When changing the air-fuel ratio A / F,
Simply controlling the air-fuel ratio to the lean side will cause misfire
It is possible. Therefore, in the present embodiment,
Simultaneously with the air-fuel ratio control described above to prevent
The ignition timing control is performed. For this reason,
The controller 50 also has a map as shown in FIG.
It is remembered. FIG. 2B shows the relationship between the engine speed Ne and the engine speed Ne.
It is an ignition timing correction map according to the engine load.
In connection with the air-fuel ratio setting map shown in FIG.
Is corrected. That is, as shown in FIG.
When the gin rotation speed Ne is less than the maximum output generation rotation speed N1
Shows the ignition timing control map (not shown) for normal operation.
Eventually, ignition timing control is performed,
The engine speed is between the maximum output speed N1 and N2
Is set in the ignition timing control map during normal operation.
A value of + 2 ° to the specified ignition timing
To be set. That is, in this case,
Ignition timing delayed by 2 ° from ignition timing during normal operation
Control is set. Similarly, when the engine speed is increased from N2
When it is between N3, the ignition timing is retarded by 4 °,
In addition, when the engine speed is from N3 to the allowable speed Nmax,
If it is in the middle, retard the ignition timing by 6 °.
ing. And such air-fuel ratio control and ignition timing control
The maximum number of revolutions of the engine 2
Drivability is impaired even if it exceeds the force generation speed N1
Engine 2 overrun (overspeed)
It can be prevented. Gas engine according to a first embodiment of the present invention
The over-rotation prevention device is configured as described above.
Then, for example, the overspeed prevention of the engine 2 is performed as follows.
Be executed. First, the engine speed sensor 3
The rotation speed Ne of the gin 2 has exceeded the maximum output generation rotation speed N1.
When this is detected, the controller 50
Based on the excess air ratio setting map shown in FIG.
The excess air ratio λ (ie, the air-fuel ratio A /
Set F). The excess air ratio set at this time
λ is the excess air ratio on the leaner side than during normal operation. When the excess air ratio λ is set,
In the controller 50, the set excess air ratio λ,
To ACV solenoid 30A so that air-fuel ratio A / F is achieved
Set the control signal of. And from the controller 50
ACV solenoid 30A is turned on in accordance with the control signal of
Opening control of ACV30 changes
As a result, the amount of air passing through the bypass passage 22A increases,
The fuel ratio A / F is changed. In this case,
The fuel supply amount is also changed so as to obtain a desired air-fuel ratio. Also, once the excess air ratio λ is set,
The operation state and fuel supply amount of the ACV solenoid 30A are as follows.
Based on the oxygen concentration information from the linear A / F sensor 13
Feedback controlled. Also, such an air-fuel ratio system
At the same time, ignition timing control is executed. That is,
The engine rotation speed Ne of the engine 2 is
When it is detected that the number of revolutions at which large output has been generated exceeds N1,
When the ignition is performed as shown in FIG.
Ignition according to the engine speed based on the period correction map
The period correction amount is set. At this time, specifically, the engine
The ignition timing is retarded as the engine speed increases.
Correction of the ignition timing is performed. FIGS. 3 (a) and 3 (b) show a gas engine of the present invention.
The output of the engine 2 and the engine
It is a figure showing the characteristic of gin rotation speed. FIG. 3 (a), (b)
As shown by the solid line in FIG.
When the number of turns is reached, the air-fuel ratio is changed to the lean side, and
Because the time is retarded, over time,
The engine speed and output are smoothly suppressed,
Overrun can be prevented. In addition,
The dotted line in the figure shows the characteristics when no control is performed.
ing. In addition, such air-fuel ratio control and ignition timing control
Control without rotating hunting
The overrun of the engine 2 can be reliably prevented.
It is. In particular, the CNG engine 2 as in the present embodiment
In this case, the normal rotation range is relatively close to the
Inevitably, the frequency of operation near the number of turns increases,
Although it is easy to exceed the maximum number of rotations,
When the rotational speed Ne of the motor 2 reaches the maximum output generating rotational speed N1,
Smooth engine speed without rotation hunting
Can reduce drivability.
Nor. Incidentally, the CNG engine 2 as described above
Is a conventional type used for buses and trucks.
It is expected to replace the diesel engine,
Diesel engine for speed control to prevent balun
It is desirable that the rotation feeling is the same as described above. In addition,
Generally, in diesel engines, the intake air volume is kept almost constant.
Determines the fuel injection amount according to the amount of depression of the accelerator pedal
Output control to prevent engine overspeed.
Even at times, the output is suppressed by reducing the fuel injection amount.
It has become. Thus, the diesel engine
Then, the output is determined by the fuel injection amount, so the engine
Output is reduced by reducing the fuel injection amount during
The number of rotations is suppressed without causing hunting etc.
You. On the other hand, in the Otto cycle engine, the main
Change the throttle opening linked to the accelerator pedal
Because the output is changed by changing the intake air volume,
When the engine 2 is over rotating (that is, the throttle opening is large)
Time), the output is smooth even if only the fuel injection amount is changed.
Cannot be suppressed and the engine speed hunts.
It will be. On the other hand, according to the present apparatus, the air-fuel ratio control
By controlling ignition and ignition timing, the conventional diesel
Engine speed can be controlled with the same characteristics as
It has the advantage of not disturbing the driver.
There is an advantage that. In addition, this device uses a conventional engine
Just add control logic to 2
Costs and weight because few additions or changes are required.
It also has the advantage of little increase in volume. Further, Japanese Patent Application Laid-Open No. Hei 7-119527 and the like
In the disclosed technology, a sub-throttle is provided in the intake passage.
However, in this device, such a sub throttle is set.
No cost and space efficiency.
There is also an advantage that. Further, the gas engine of the present invention
Excessive rotation prevention device uses conventional air-fuel ratio control
This has the advantage that it can be easily realized.
is there. The maps shown in FIGS. 2 (a) and 2 (b)
The values of the excess air ratio λ and the ignition timing correction amount are examples.
It is not necessarily limited to such values.
Not. (B) Description of the second embodiment Next, a gas engine according to a second embodiment of the present invention will be described.
The rotation preventing device will be described with reference to FIGS. Also in the second embodiment, the first
As in the embodiment, the engine 2 is an Otto cycle engine.
Which uses compressed natural gas (CNG) as fuel
It is configured as a G engine. As shown in FIG.
The compressed natural gas is stored in the fuel tank 4 in a high pressure state.
The high-pressure gas in the fuel tank is
Through the supply passage 10 and the intake passage 22 of the engine 2, the engine
The gin 2 is supplied to the combustion chamber. Soshi
The fuel supplied into the combustion chamber is
It is ignited and then discharged to the exhaust passage 23.
ing. The high-pressure gas is supplied to the fuel supply passage 10 from the upstream side.
Valve 8, fuel pressure regulator 16, and fuel supply amount
A control device (gas valve) 18 is interposed. This
The fuel pressure regulator 16 has a high pressure inside the fuel tank.
Built-in residual pressure sensor 16A for detecting residual gas pressure
The gas valve 18 has a gas temperature sensor 18A.
Is built-in. The high-pressure gas in the fuel tank 4 is
Is adjusted to a predetermined pressure by the fuel pressure regulator 16.
After a predetermined time via the gas valve 18
The amount injected from the gas injection nozzle 20 into the intake passage 22 is
It is supposed to be. Also, above the gas injection nozzle 20
The air cleaner 27 and the air flow sensor 24
Is provided. The air flow sensor 24 is
In this case, the intake air amount is detected.
Detects the number of Karman vortices generated inside
A Karman vortex airflow sensor that measures
You. The intake passage 22 is provided with a gas injection nozzle.
The main throttle 26 and the air
Branched in two directions with the control throttle 29
And the main throttle 26 changes the idle rotation state.
Idle speed control valve as adjusting means
(ISCV) 28 and the like. Idol speed
Driver control valve (ISCV) 28
Release the accelerator pedal and release the throttle valve 26A.
Prevents engine stall when fully closed
Is provided to allow for idle
To control the open / close state of the ISCV 28.
The intake air that bypasses the throttle valve 26A
Adjust the amount. Note that this ISCV 28 has a predetermined
Step motor that rotates in steps
The open / closed state of the ISCV 28 will be described later.
Based on a control signal from a controller (control means) 50
And is controlled. Also, the main slot
The throttle 26 has a throttle position as shown in FIG.
A sensor (TPS) 61 is provided.
1 so that the opening of the throttle valve 26A is detected.
Has become. On the other hand, the air control throttle 29
Is an intake air amount control valve for performing air-fuel ratio control.
(Air control valve or ACV) 30 or this A
A bypass valve 30C for bypassing the CV 30 is provided.
Is provided. This ACV 30 has a butterfly type
Throttle valve 30B is attached, ACV30
Air control slot by controlling the operation of
The flow rate of the intake air flowing through the pipe 29 has been adjusted
I have. In the ACV 30, the main throttle 2
6 larger than the intake volume secured by the ISCV 28
Intake can be taken in. The exhaust passage 23 of the engine 2 is
An exhaust temperature sensor 15 for detecting the exhaust temperature in the medium 25 is provided.
Is provided. The exhaust passage 23 has an exhaust brake
A key valve 17 is also provided so that the driver
When the deceleration operation is performed, the exhaust brake valve 17
The exhaust passage 23 is narrowed. Further, this engine 2 is not shown.
However, the fuel gas leaked from the cylinder head etc.
PCV (positive clutch)
NkCase Ventilation = Positive Crankcase Ven
(tilation) valve is also provided. Well, here
The main part of the present apparatus in the second embodiment will be described.
The engine 2 detects the engine speed.
A rotational speed sensor (engine rotational speed detecting means) 3 is provided.
The engine speed sensor 3 is used as control means.
Connected to all the controllers 50. Then, the controller 50
Engine 2 based on information from the gin rotational speed sensor 3.
Overrun (overrun) is prevented.
Specifically, in the second embodiment, the throttle valve 26
A directly controls A to control the output of engine 2.
No, it is designed to prevent overruns
You. Here, attention is paid to the main throttle 26.
As shown in FIG. 5, the throttle valve 26A
Connected to the accelerator pedal 63 via the lever 62
The throttle in accordance with the amount of depression of the accelerator pedal 63.
The opening degree of the tor valve 26A changes. Ma
As shown in FIG. 5, the throttle valve 26A has
The actuator 64 is connected via the throttle lever 65.
Is tied. The actuator 64 is connected to the engine 2
Solenoid valve (not shown)
Omitted) and this solenoid valve
By controlling the duty, desired control room 64b
Applying a negative pressure of magnitude to drive the rod 64a in the axial direction
It is supposed to. For example, a negative pressure acts on the control chamber 64b.
Then, against the urging force of the return spring 64c,
The pad 64a is driven upward in the figure.
When the solenoid valve is turned off, the control room 6
4b is no longer subjected to negative pressure, and the return spring 64
The rod 64a is driven downward in the figure by the urging force of c.
It is becoming so. Further, the tip of the rod 64a (in the figure,
The lower end) is attached to one end of the throttle lever 65 described above.
The other end of the throttle lever 65 is connected
It is connected to the rottle valve 26A. Therefore, the slot
The throttle valve 26A is connected to the accelerator pedal 63 and the actuator.
Drive 64, but the access
The pedal 63 and the actuator 64 are independent
Actuated by the actuator 64.
Even if the throttle valve 26A is driven, the accelerator pedal
63 is not linked to the throttle valve 26A
You. Similarly, the accelerator pedal 63 is used to switch
Even if the rottle valve 26A is driven, the actuator 64
Are not linked to the throttle valve 26A. On the other hand, attention is paid to the control system of the present apparatus.
As shown in FIG. 6, the controller 50 includes a TPS
61, the throttle opening TP0 detected by the
The amount of intake air detected by the flow sensor 24 and the
Engine speed N detected by gin speed sensor 3
e is input to the controller 50
Then, the actuator 64 and the
The control signal to the gas injection nozzle 20 is set.
ing. That is, the engine speed sensor 3
Thus, the rotation speed Ne of the engine 2 becomes a predetermined rotation speed (for example,
It is detected that the maximum output rotation speed of the engine 2) N1 has been reached.
When issued, the controller 50 causes the actuator
64 is driven to reduce the amount of intake air.
You. Further, the engine speed Ne is higher than the predetermined speed N1.
Also reached a high predetermined speed (for example, allowable speed) N2
Is detected, the controller 50 executes the fuel injection
To prevent overrun.
ing. Here, an electronic fuel injection device is provided.
In the engine, the basic fuel injection amount is determined by the controller 50.
The throttle valve is set in proportion to the intake air volume.
To reduce the amount of intake air by forcibly squeezing 26A
The fuel injection amount can be reduced, and the output
Can be reduced. For this reason,
In the controller 50, the actuator is operated as follows.
64 throttle opening control
You. First, the rotation speed Ne of the engine 2 is less than a predetermined rotation speed N1.
If it is below, the opening control of the throttle valve 26A is performed.
The opening degree is determined according to the depression amount of the accelerator pedal 63.
You. When the engine speed Ne is equal to the predetermined speed N
When it is detected that the number exceeds 1, the slot
Target TP_objIs set. TP_obj= TP₀
× K_NeIn the above equation, TP₀Is the actual throttle opening
, K_NeIs a slot set according to the engine speed
This is the opening degree correction coefficient (correction gain). Figure 8 shows the control
Correction gain K stored in the controller 50_NeAn example of a map of
However, as shown in this map, the correction gain K
_NeIs set according to the engine speed Ne. What
Contact, target throttle opening TP_objIs real from TPS61
Feedback control is performed based on the throttle opening TP0.
It is. When the engine speed Ne is equal to the predetermined speed N
2 is detected, the controller 50
The fuel injection stop signal is set and the gas injection nozzle 20
Is stopped. by the way,
FIG. 7 shows the throttle opening characteristics and the engine in this device.
2 shows an output characteristic. Here, referring to FIG.
The characteristics of throttle opening and engine output.
Just explain. First, the engine speed Ne is equal to a predetermined speed.
When N1 is exceeded, the throttle is controlled by the throttle opening control described above.
The throttle opening is gradually set smaller and the output of the engine 2
Also decreases at a predetermined rotational speed N1. Further engine rotation
When the number rises above N1 and reaches N2, the fuel injection control
It is executed and the output drops sharply. Then, the throttle opening control is performed as described above.
By doing so, it is possible to avoid sudden output torque fluctuations.
And ensure that no drivability is lost.
The overrun of the gin 2 can be prevented.
Over-rotation prevention of gas engine as a second embodiment of the present invention
Since the stop device is configured as described above, for example,
Control is executed according to the flowchart shown in Fig. 9.
Is done. First, at step S1, the engine speed
Based on the detection information from the sensor 3, the engine speed N
It is determined whether or not e is equal to or less than a predetermined rotation speed N1. And d
If the engine rotation speed Ne is less than the predetermined rotation speed N1,
If the rotation speed is higher than the predetermined rotation speed N1, the process proceeds to step S2.
No. In step S2, the device provided in the controller 50
Based on the map (see FIG. 8).
Gain K according to_NeAnd the current
Taking the throttle opening TP0 from TPS61,
The target throttle opening TP is calculated by the following equation._objSet. TP_obj= TP₀× K_Ne And such a target throttle opening TP_objBecomes
Actuator 64 is driven as described above. Next,
In step S3, the engine speed Ne is set to a value less than the predetermined speed N1.
Is not higher than the predetermined rotation speed N2.
Return if the gin rotation speed Ne is equal to or less than the predetermined rotation speed N2.
I do. On the other hand, when the engine speed Ne becomes the predetermined speed N
If it is larger than 2, the process proceeds to step S4 and the fuel cut
After execution, it returns. The engine times
If the number of turns is less than N2, the basic fuel injection amount is
Air-fuel ratio A / F is almost constant
It becomes. As described above, according to the second embodiment, the engine rotation
Since the amount of intake air is controlled according to the number of turns, the engine
When the number of revolutions exceeds the specified number of revolutions N1, the engine output is smooth
Is suppressed, and the overrun of the engine 2 is reliably suppressed.
be able to. Further, the throttle opening control is performed as described above.
By doing so, sudden torque fluctuations can be avoided,
The advantage is that it does not impair drivability.
You. Further, the engine speed is higher than the predetermined speed N1.
When the predetermined rotation speed N2 is reached, the fuel injection is stopped.
The engine 2 can be reliably protected.
There are points. Further, one throttle valve 26A is accessed.
Connected to both the pedal 63 and the actuator 64,
So that they independently control the throttle valve 26A
Subthrottle as in the prior art
There is an advantage that no valve needs to be provided. That is,
In conventional technology, the main slot connected to the accelerator pedal
A sub-throttle valve is provided in series with the throttle valve.
Actuator by connecting the actuator to the rottle valve
Control the sub-throttle valve opening by controlling the operation of the
Control, but with such a configuration
Requires two throttle valves and a throttle
There has been a problem that the overall size and cost are increased. On the other hand, the gas engine of the present invention
In the rotation preventing device, the throttle valve 26A is
Function as a throttle valve and as a sub-throttle valve
Of the main throttle 26
There is no increase in size and cost. Also, as mentioned above
According to such a configuration, a sub-throttle valve is provided.
For conventional technology, reduce the length of the throttle section.
So the volume of the main throttle part can be reduced
Wear. In this case, fuel is supplied from the injection nozzle 20 to the intake passage 2.
In a gas engine that injects fuel (gas) to
In particular, the responsiveness to accelerator operation has been improved, and air-fuel ratio control
Also has the advantage that it can be performed with high accuracy. Air-fuel ratio system
The purification performance of exhaust gas also improves with the improvement of control accuracy
There are advantages. The throttle opening shown in the map of FIG.
The value of the correction coefficient KNe is merely an example, and is required.
The invention is not limited to such values. [0064] As described in detail above, the gas engine of the present invention
According to the gin over-speed prevention device, the engine speed is
If the engine speed is exceeded, the intake air volume
Is controlled, the engine output is smoothly suppressed,
An advantage that can reliably suppress overspeed of the gas engine
There are points. In addition, by controlling the amount of intake air,
Avoid sudden torque fluctuations during engine speed suppression
And does not impair drivability.
There are points. Also, one throttle valve is connected to an accelerator pedal.
Connected to both the actuator and the actuator,
Is configured to control the throttle valve
Therefore, it is necessary to provide a sub throttle valve as in the prior art.
This increases the size of the throttle and increases costs
There is an advantage that it does not invite. This also
The advantage is that the engine can be easily mounted on vehicles.
You.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an overall configuration of a gas engine overspeed prevention device as a first embodiment of the present invention. FIG. 2 is a map showing a setting example of an excess air ratio and an ignition timing correction amount in the overspeed prevention device for a gas engine as the first embodiment of the present invention. FIG. 3 is a view for explaining an operation of the overspeed prevention device for the gas engine as the first embodiment of the present invention. FIG. 4 is a schematic diagram showing an overall configuration of a gas engine overspeed prevention device as a second embodiment of the present invention. FIG. 5 is a schematic diagram showing a configuration of a main part of a gas engine overspeed prevention device according to a second embodiment of the present invention. FIG. 6 is a diagram focusing on a control system of an overspeed prevention device for a gas engine as a second embodiment of the present invention. FIG. 7 is a diagram showing characteristics of an output and a throttle opening in a gas engine overspeed prevention device as a second embodiment of the present invention. FIG. 8 is a map showing a setting example of a throttle opening correction coefficient in a gas engine overspeed prevention device as a second embodiment of the present invention. FIG. 9 is a flowchart for explaining the operation of the overspeed prevention device for a gas engine according to the second embodiment of the present invention. FIG. 10 is a view for explaining a conventional overspeed prevention device for a gas engine. FIG. 11 is a view for explaining a conventional overspeed prevention device for a gas engine. FIG. 12 is a view for explaining a conventional overspeed prevention device for a gas engine. [Description of Signs] 2 Gas engine (CNG engine) 3 Engine speed sensor (engine speed detecting means) 4 Fuel tank 10 Fuel supply path 13 Linear A / F sensor 15 Exhaust temperature sensor 16 Fuel pressure regulator 16A Residual pressure sensor 17 Exhaust brake valve 18 Gas valve 18A Gas temperature sensor 19 Distributor 20 Gas injection nozzle 21 Spark plug 22 Intake passage 23 Exhaust passage 24 Air flow sensor 25 Catalyst (catalyst integrated muffler) 26 Main throttle 26A Throttle valve (throttle valve) 27 Air cleaner 28 Idle speed control Valve (ISC
V) 29 Air control throttle 30 Intake air amount control valve (air control valve or ACV) 30A ACV solenoid 30B ACV throttle valve 30C Bypass valve 50 Controller (ECU) as control means 61 Throttle position sensor (TPS) 62 Accelerator lever 63 Accelerator pedal 64 Actuator 64a Rod 64b Control room 64c Return spring 65 Throttle lever

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (Reference) F02M 21/02 301 F02M 21/02 301D F-term (Reference) 3G084 AA05 BA03 BA05 BA09 CA09 DA08 DA35 EA07 EA11 FA07 FA10 FA26 FA27 FA29 FA33 3G301 HA22 JA06 JA34 KA25 KA26 LA03 MA01 MA12 MA24 NA07 NC02 NE06 NE15 PA01Z PA11Z PD02Z PE01Z

Claims (1)

Claims: 1. A throttle valve interposed in an intake passage of a gas engine and interlocked with an accelerator pedal, an actuator connected to the throttle valve, and an engine speed for detecting a rotation speed of the gas engine. A number detecting means, and a control means for controlling the operation of the actuator based on the detection information from the engine speed detecting means, wherein the engine speed detecting means causes the gas engine speed to exceed a predetermined speed. An over-rotation prevention device for a gas engine, characterized in that the control means controls the operation of the actuator to reduce the amount of intake air.