JPH0842400A - Gas engine control device - Google Patents

Abstract

PURPOSE:To provide such a compact gas engine control device as controlling engine power in a wide range without being affected by the pressure change of a gas supply source and easily allowing for various types of gas. CONSTITUTION:Fuel gas flows from a pressure gas source 5 through an opening/ closing valve 6 into a control valve 7. The control valve 7 formed with a proportional electromagnetic valve controls the supply pressure of the fuel gas in respect to the size of a carried current without relying on the supply source pressure of the fuel gas. The fuel gas controlled such a way is injected from an injection nozzle 9 arranged in a detachable manner after flowing out of the control valve 7, mixed with air entered into a suction pipe 2 via an air cleaner 3 and supplied to a gas engine 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas engine control device, and more particularly to LPG (liquefied propane gas) and L gas.
The present invention relates to a control device for a gas engine that controls a pressurized gas such as BG (liquefied butane gas) as fuel to perform a substantially constant speed operation.

[0002]

2. Description of the Related Art There is known a gas engine in which a pressurized fuel gas such as LPG or LBG is supplied to an engine through a pressure regulator and burned by the engine.

In the conventional gas engine of this type, the pressurized gas is depressurized to a substantially atmospheric pressure via a pressure regulator, and the fuel gas is supplied to the engine by the negative suction pressure of the engine. That is, in the gas engine, the intake air amount is controlled by the throttle valve, and the gas amount suitable for the controlled intake air amount is supplied to the engine. Therefore, in this case, it is necessary to install a throttle valve in the intake pipe,
Since the layout of the intake pipe and the layout of the throttle valve are restricted by the layout of the engine, these layout restrictions occur. For this reason, it is difficult to downsize the gas engine, and a wire for controlling the throttle valve or the like is required, which makes it difficult to simplify the device.

Therefore, there has been proposed an attempt to control the engine output by controlling only the flow rate of the fuel gas without providing a throttle valve in the intake pipe, thereby making the engine compact and simple. (For example, JP-A-2-
No. 23258).

In the above gas engine, the pressure regulator and the control valve are arranged in series on the downstream side of the pressurized gas source, and the passage area of the fuel gas adjusted to a constant pressure by the pressure regulator is variably controlled by the control valve. By doing so, the supply amount of the fuel gas is controlled, and the fuel gas whose flow rate is controlled is mixed with air and supplied to the engine. Further, when the supply pressure to the control valve fluctuates, the fuel supply amount changes greatly.Therefore, even in the gas engine, it is possible to prevent the supply pressure of the fuel gas to the control valve from fluctuating via the pressure regulator. There is.

[0006]

However, in any of the gas engines described above, it is necessary to secure an installation space for the pressure regulator because the pressure regulator is provided as described above to adjust the supply pressure from the pressurized gas. Therefore, there is a problem in that it is an obstacle to downsizing the device. That is, since the pressure regulator is a relatively large component, it is necessary to secure a large mounting space, which makes it difficult to downsize the device.

Further, when the gas type of the fuel gas is changed and used, for example, when the gas type is changed from LPG to LBG, the calorific value is different, so that the maximum passage area of the fuel gas needs to be changed. There is a problem that the control valve itself has to be replaced in such a case.

The present invention has been made in view of the above problems, and it is compact and can control the engine output in a wide output range without being affected by the pressure fluctuation of the gas supply source. Moreover, it is an object of the present invention to provide a gas engine control device that can easily cope with various gas types.

[0009]

In order to achieve the above object, the present invention relates to a gas engine controller for mixing a fuel gas supplied through a control valve with air and supplying the mixed gas to an engine. A gas nozzle for injecting fuel gas is removably disposed on the downstream side of the fuel cell, and the control valve supplies the fuel gas according to the magnitude of the energizing current without depending on the pressure of the fuel gas supply source. It is characterized by being composed of an electromagnetic proportional valve that controls pressure.

Specifically, the solenoid proportional valve is a movable valve for adjusting the flow rate of fuel gas, a valve housing having the movable valve therein, and a valve housing connected to the valve housing. It is characterized in that the movable valve has an exciting part for controlling the operation, and the movable valve has a pressure adjusting mechanism for adjusting the supply pressure.

Further, according to the present invention, an air-fuel ratio control means for controlling an air-fuel ratio of an air-fuel mixture by a gas amount of the fuel gas controlled by the control valve, and an operating state detecting means for detecting an operating state of the gas engine. And ignition timing calculation means for calculating the ignition timing of the gas engine based on the detection result of the operating state detection means, and the ignition timing when the air-fuel ratio is below a predetermined value and in a lean limit state. It is characterized by having an ignition timing correction means for controlling the engine output by correcting the above.

Further, the intake system of the gas engine is not provided with a throttle valve for controlling the intake air amount.

Further, the operating state detecting means includes at least an engine speed detecting means for detecting an engine speed, and the combustion of the gas engine is performed based on a variation amount of the engine speed detected by the engine speed detecting means. And a lean limit determining means for determining whether or not the air-fuel ratio is less than or equal to the predetermined value based on the determination result of the combustion state determining means. Further, the ignition timing correction means is a retard angle correction means for retarding the ignition timing, and the engine output is reduced as the ignition timing is retarded.

[0014]

According to the above construction, the fuel gas of a predetermined flow rate controlled to a constant pressure flows out from the control valve, is injected from the gas injection nozzle, is mixed with air, and is supplied to the gas engine.

The flow rate of the fuel gas flowing out of the control valve is controlled by the movable valve, and in this case, the gas pressure of the fuel gas flowing out of the control valve is kept constant via the pressure adjusting mechanism of the movable valve. It

Further, when the gas type is changed, it is possible to deal with it by exchanging the detachably arranged gas injection nozzle.

Further, the control of the air-fuel ratio is performed only by the fuel gas amount without controlling the intake air amount by the throttle valve, and according to the operating condition of the engine (optimal).
The ignition timing is calculated, and when the air-fuel ratio of the air-fuel mixture is in the lean limit state where the air-fuel ratio is equal to or less than a predetermined value, the ignition timing is corrected.

Specifically, the combustion state of the engine is determined based on the amount of change in the engine speed, and it is determined whether the engine is in the lean limit state based on the combustion state. Further, when it is determined that the engine is in the lean limit state, the engine output is controlled in the lean limit region by gradually reducing the thermal efficiency while continuing combustion by retarding the ignition timing. Be seen.

[0019]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is an overall configuration diagram showing an embodiment of a gas engine control device according to the present invention.

In the figure, reference numeral 1 is a four-cycle gas engine (hereinafter, simply referred to as "engine"). An air cleaner 3 is provided at the tip of an intake pipe 2 of the engine 1, and a space between the air cleaner 3 and the engine 1 is provided. Is the fuel supply pipe 4
Is branched from the intake pipe 2.

At the tip of the fuel supply pipe 4, LPG or L
A pressurized gas source 5 such as a gas cylinder filled with a fuel gas such as BG is mounted, and an on-off valve 6 and a control valve 7 are sequentially installed in the middle of the fuel supply pipe 4 downstream of the pressurized gas source 5, Further, a gas nozzle 9 for injecting fuel gas is arranged on the downstream side of the control valve 7 and near the branch portion of the intake pipe 2. The on-off valve 6 and the control valve 7 are electrically connected to an electronic control unit (hereinafter referred to as “ECU”) 8 and controlled by the ECU 8. The gas nozzle 9 is detachable so that it can be changed according to the type of gas.

The on-off valve 6 is a normally-closed solenoid valve, and
ON / OFF control is performed by a command from the CU8. That is,
When the engine 1 is stopped, the fuel gas from the pressurized gas source 5 is turned off and closed to prohibit it from being supplied to the engine 1. When the engine 1 is driven, it is turned on and opened to open the fuel gas. Supply to.

The control valve 7 controls the flow rate of the fuel gas amount Q passing through the fuel supply pipe 4 according to a command from the ECU 8.
That is, the engine load of the control valve 7 is increased and the engine speed NE becomes a predetermined speed NEX (for example, 2500 rpm).
m) When the air-fuel ratio of the air-fuel mixture supplied to the engine 1 becomes fuel lean when the fuel gas amount Q falls below
To control the flow path of the fuel gas so that the fuel gas amount is decreased when the engine speed NE is a high speed equal to or higher than the predetermined speed NEX or when the air-fuel ratio of the air-fuel mixture is fuel rich. Controls the flow path of fuel gas.

As shown in FIG. 2, the control valve 7 is an electromagnetic proportional valve that controls the supply pressure of the fuel gas according to the magnitude of the energizing current without depending on the pressure of the pressurized gas source. It is configured.

That is, the control valve 7 includes a valve housing 12 having an inflow port 10 through which the fuel gas flows in and an outflow port 11 through which the fuel gas flows out, and the valve housing 12
It comprises a movable valve 13 internally included in the movable valve 13 and an exciting unit 14 for controlling the operation of the movable valve 13.

Specifically, the movable valve 13 is a valve that is seated between the valve body 15 made of Al or the like and the valve body 15 and the bottom lid 50 to elastically urge the valve body 15 in the direction of arrow A. Spring 16 and NBR mounted on top of valve housing 12
And the like, a substantially flat diaphragm 17, a stem 18 that connects the diaphragm 17 and the valve body 15, and a substantially T-shaped projection 19 provided on the upper end of the stem 18.
A diaphragm pressing spring 20 that is seated between the protrusion 19 and the diaphragm 17 to press and urge the diaphragm 17, and a diaphragm pressing plate 21 that holds the diaphragm 17 between the diaphragm 17 and the valve housing 12. Has been done. Then, a hole 22 is formed through the side wall of the diaphragm pressing plate 21 to introduce the atmosphere. That is,
An atmospheric pressure chamber 23 is formed between the diaphragm 17 and the diaphragm pressing plate 21.

The exciting section 14 includes an exciting coil 24,
A plunger 25 that reciprocates in the direction of arrow B according to the magnitude of the energizing current of the exciting coil 24, and an adjusting screw 26 that adjusts the stroke of the plunger 25 within a predetermined allowable range.
And an upper lid 27 screwed to the adjusting screw 26, and the adjusting screw 2
6 is seated between the upper end of the plunger 25 and the plunger 25 and elastically urges in the direction of arrow C, and the plunger 25 is seated between the plunger 25 and the diaphragm retainer plate 21 to spring the plunger 25 in the direction of arrow D. It is composed of a plunger lower spring 29 for urging and urging.

In the control valve 7 thus constructed, when the exciting coil 24 is energized, the plunger 25 resists the elastic urging force of the lower plunger spring 28 by the attractive force corresponding to the magnitude of the energized current. Is pushed downward, the valve body 15 moves downward via the stem 18 and opens the valve, and the fuel gas flows from the inflow port 10 to the outflow port 11.
That is, since the plunger stroke is variable by the energizing current, a flow rate linearly proportional to the energizing current flows out from the outlet 11. Further, the atmospheric pressure chamber 23 has a hole 2
Since it communicates with the atmosphere through 2, the atmospheric pressure is always maintained. Therefore, when the gas pressure of the supplied fuel gas flowing into the inflow port 10 becomes high, the diaphragm 17 is pushed upward, and as a result, through the stem 18. Diaphragm 1
The valve body 15 that is connected to the valve 7 is also pushed upward, and the valve body 15 moves in the valve closing direction. On the other hand, when the gas pressure of the supplied fuel gas becomes low, the diaphragm 17 is pushed down, so that the valve body 15 is also pushed down and the valve body 15 moves in the valve opening direction. In this way, the diaphragm 17 and the diaphragm pressing plate 21 constitute a pressure adjusting mechanism, and the gas pressure of the fuel gas flowing out from the control valve 7 is kept substantially constant. As a result, the supply pressure can be kept substantially constant without using a pressure regulator as in the related art, so that the pressure regulator can be omitted and the device can be made compact.

A crank angle (CRK) sensor 30 and an ignition pulsar 31 are provided around the crank shaft (not shown) of the engine 1. The CRK sensor 30
A pulse signal (hereinafter referred to as “CRK signal pulse”) is output at the piston top dead center position, and this CRK signal pulse is output.
Supply to CU8. The ignition pulser 31 generates an ignition pulse signal at a predetermined crank angle position and supplies the ignition pulse signal to the ECU 8.

The ignition device 32 of the engine 1 is connected to the ECU 8 and its ignition timing is controlled by a command from the ECU 8. A starter motor 33 is connected to the engine 1, and the engine 1 is started by the starter motor 33.

A wide-range oxygen concentration sensor (hereinafter referred to as "LAF sensor") 35 is provided in the middle of the exhaust pipe 34 of the engine 1. The oxygen concentration in the exhaust gas detected by the LAF sensor 35 is an electric signal. Converted to ECU
8 is supplied.

The ECU 8 shapes an input signal waveform from the various sensors, corrects a voltage level to a predetermined level, converts an analog signal value into a digital signal value, and the like, and a central processing circuit. (Hereinafter referred to as “CPU”), storage means for storing various calculation programs executed by the CPU, calculation results, etc., and an output circuit for supplying a drive signal to the on-off valve 6, the control valve 7, etc. .
In addition, the ECU 8 controls the generation time interval ME of the CRK signal pulse
Engine speed NE which is the reciprocal of this ME value
To calculate.

Further, the ECU 8 detects the crank angular velocity based on the CRK signal pulse, and determines the combustion state of the engine 1 according to the variation state of the crank angular velocity.

That is, the instantaneous rotation speed of the engine 1,
That is, as shown in FIG. 3, the instantaneous crank angular velocity drops most near the position where the ignition pulse signal is generated due to the compression resistance of the air-fuel mixture supplied to the engine 1, and then the crankshaft is accelerated by the gas pressure due to combustion. Although the crank angular velocity increases, when the engine 1 is causing irregular combustion, the crank angular velocity becomes smaller than that during normal combustion. Therefore, the crank angular velocity at the time when the crank angular velocity reaches a substantially maximum value after a lapse of a predetermined time t after the ignition pulse signal is generated, the crank angular velocity value is held and the deviation ΔTREV of the hold value between cycles is obtained. The combustion state of the engine 1 is detected by calculating That is, when the deviation ΔTREV is less than or equal to the predetermined reference value MFREF, it is determined that the engine 1 is normally combusting, and the deviation ΔTREV is the predetermined reference value MF.
When it is REF or more, it is determined that the engine 1 is burning irregularly. Further, when the deviation ΔTREV is larger than the predetermined misfire determination value MFH, it is determined that the engine 1 is in the misfire state.

However, the control device of the present gas engine is
The optimum ignition advance value θIGY is calculated according to the engine speed NE and the excess air ratio λ, and when the engine 1 reaches the lean limit, the optimum ignition advance value θIGY is retarded and thus retarded. The engine output is controlled by controlling the ignition timing with the set ignition advance value θIG. That is, in the gas engine, as shown in FIG. 4, when the excess air ratio λ exceeds, for example, “1.6” and enters the irregular combustion region, the engine output has a characteristic of sharply decreasing (point A in the figure). Indicates the lean limit point that indicates the boundary between the irregular combustion region and the fuel gas control region). That is, the engine output can be controlled by decreasing the supply gas amount until the lean limit of the air-fuel ratio is reached, but if the air-fuel ratio exceeds the lean limit point A, irregular combustion becomes remarkable,
As indicated by the broken line, the amount of unburned gas components such as HC that are discharged may increase rapidly, and the exhaust gas purification efficiency may deteriorate extremely.
In other words, in the case of a gas engine that uses a gas such as LPG as a fuel, the engine output can be controlled only by controlling the fuel gas until the excess air ratio λ is about “1.6”. Is more than "1.6", the misfire rate sharply increases, the rotation fluctuation also increases, and the emission of unburned gas components also sharply increases. Therefore, only controlling the fuel gas amount Q controls the actual engine output. Will be difficult to do. That is, since the amount of decrease in engine output is controlled by the amount of increase in misfire rate, control of only the fuel gas amount Q allows stable control of engine output over a wide range from the no-load state of the engine to the maximum output range. You cannot do it. On the other hand, there is a relationship as shown in FIG. 5 between the ignition advance value θIG and the engine output η (λ = 1.6),
The engine output η has a parabolic characteristic having a maximum value at the optimum ignition advance value θIGY (for example, 45 ° BTDC) with respect to the ignition advance value θIG. That is, the engine output η is the optimum ignition advance value θIG with respect to the ignition advance value θIG.
It becomes maximum when Y, and gradually decreases as it is displaced to the advance side or the retard side. Therefore, the ignition advance value θI
G is the lower limit ignition advance value θIGX from which the engine output becomes “0”% from the optimum ignition advance value (for example, 45 ° BTDC)
The engine output can be gradually changed by performing the retard correction until reaching (for example, −10 ° BTDC), whereby the engine output is continuously stabilized from the no-load state to the maximum output. Can be controlled to. Hereinafter, the control procedure will be described in detail.

FIG. 6 is a flow chart of the gas amount control routine. This program is executed when the complete explosion state of the engine 1 is detected, for example, when the engine is started and the engine speed NE becomes 800 rpm or more. to start.

When this program is started, the engine speed NE (calculated based on the detection signal of the CRK sensor 29) and the excess air ratio λ (calculated based on the detection signal from the LAF sensor 34) are read ( Step S
1) Then, the θIGY map is searched to calculate the optimum ignition advance value θIGY according to the operating state of the engine (step S2).

Specifically, the θIGY map is, as shown in FIG. 7, a map value θIGY (0 with respect to engine speeds NE00 to NE19 and excess air ratios λ00 to λ16.
0,00) to θIGY (16,19) are given in a matrix, and the optimum ignition advance value θIGY is such θ.
By searching the IGY map, the optimum value is set according to the operating state of the engine 1.

Next, in step S3, an ignition timing control routine, which will be described later, is executed to perform ignition timing control, and in the following step S4, the engine speed NE is the allowable limit speed N.
It is determined whether or not the rotation speed is higher than EHLT (for example, 4000 rpm). When the engine speed NE exceeds the permissible limit speed NEHLT, the engine 1 is stopped (step S5) and the program ends.

On the other hand, the determination result of step S4 is negative (N
o), that is, when the engine speed NE is lower than the permissible limit speed NEHLT, the process proceeds to step S6, where the engine speed NE is higher than a predetermined speed NEX (eg, 2500 rpm) lower than the permissible limit speed NEHLT. Or not. If the determination result is affirmative (Yes), the valve opening of the control valve 8 is reduced to reduce the fuel gas amount Q, and the air-fuel ratio of the air-fuel mixture is shifted to the leaning direction (step S7). Return to S1.

Further, the determination result of step S6 is negative (N
In the case of o), that is, when the engine speed NE is lower than the predetermined speed NEX, the routine proceeds to step S8, and it is determined whether the excess air ratio λ is “1” or larger than “1”, that is, the air-fuel ratio of the air-fuel mixture is It is determined whether the stoichiometric air-fuel ratio has already been reached or the fuel is lean. And step S
When the determination result of 8 is negative (No), that is, when the air-fuel ratio of the air-fuel mixture is fuel rich, the amount of the fuel gas Q is reduced to control the air-fuel ratio of the air-fuel mixture in the lean direction (step S7). Return to S1. It should be noted that λ = 1 is used as the determination threshold here because the fuel is gas and a sufficient combustion state is obtained at the stoichiometric air-fuel ratio, and it is not necessary to make the air-fuel ratio of the air-fuel mixture richer than that. is there.

On the other hand, the determination result of step S8 is affirmative (Y
es), that is, when the air-fuel ratio of the air-fuel mixture has not reached fuel rich, the fuel gas amount Q is increased so as to shift the air-fuel ratio of the air-fuel mixture to the rich direction (step S9) and the process returns to step S1.

FIG. 8 is a flow chart of the ignition timing control routine executed in step S3 (FIG. 6).

In step S11, the rotational fluctuation amount ΔTREV of the crank angular velocity is measured, and in the following step S12, it is determined whether or not the flag FMF is set to "1". Here, the flag FMF is "0" when the rotation variation amount ΔTREV of the crank angular velocity is equal to or less than the predetermined reference value MFREF, that is, when the engine 1 does not generate irregular combustion.
Is set to a predetermined reference value MFREF or more, that is, is set to "1" when irregular combustion occurs. As described above, in step S12, it is determined whether or not the engine 1 is causing irregular combustion based on the rotation variation amount ΔTREV of the crank angular velocity. Then, when the flag FMF is set to "1" and it is determined that the engine 1 is causing irregular combustion, it is determined that the air-fuel ratio of the air-fuel mixture is in the lean limit region, and the routine proceeds to step S13.

At step S13, the current ignition advance value θI
G is the lower limit ignition advance value θIGX (for example, −10)
° BTDC) is larger than the above. When the determination result is affirmative (Yes), the ignition advance value θIG
Is retarded by a predetermined angle θIGR (for example, 1 °) to calculate a new ignition advance value θIG (step S14), and the process returns to the main routine (FIG. 6).

When the determination result of step S13 is negative (No), that is, when the ignition advance value θIG is equal to or lower than the lower limit ignition advance value θIGX, the ignition advance value θIG is set to a predetermined angle θIGA (for example, 1 A new ignition advance value θIG (step S16) and the process returns to the main routine (FIG. 6).

On the other hand, when the determination result of step S12 is negative (No) and it is determined that the irregular combustion is not performed, the routine proceeds to step S15, where the current ignition advance value θIG is the optimum ignition advance value θIGY ( For example, it is determined whether it is smaller than 45 ° BTDC). When the determination result is affirmative (Yes), the ignition advance value θIG is set to the predetermined angle θI.
A new ignition advance value θIG is calculated by advancing GA (for example, 1 °) (step S16), and the process returns to the main routine (FIG. 6).

When the result of the determination in step S15 is negative (No), the process proceeds to step S14 and the predetermined angle θIG
A new ignition advance value θIG is calculated by retarding R, and the process returns to the main routine (FIG. 6).

As described above, according to the present invention, in the region where irregular combustion does not occur, the ignition timing control is performed so that the ignition advance value θIG becomes the optimum ignition advance value θIGY, and the fuel gas is changed according to the operating state. The amount Q is controlled, and the engine output is controlled substantially only by the air-fuel ratio control.

On the other hand, when the engine 1 is at the lean limit at which irregular combustion can occur, the fuel gas amount is supplied in a substantially fixed amount to maintain the air-fuel ratio at the lean limit (for example, λ = 1.6) and retard the ignition timing. By correcting, the engine output is controlled. That is, even when the engine is in the lean limit at which irregular combustion can occur, the fuel gas amount Q is supplied in a substantially constant amount, so when the engine speed decreases, the air-fuel ratio of the air-fuel mixture becomes rich and the engine speed increases. As the engine speed increases, the air-fuel ratio of the air-fuel mixture becomes thin and the engine speed decreases.Therefore, the engine speed is stabilized and controlled to reduce irregular combustion. Even when the engine is running, the engine speed can be stabilized. That is, when a throttle valve is arranged in the intake system to control the intake air amount like a conventional gas engine, there is a possibility that the engine speed may become unstable or engine stall may occur due to irregular combustion. On the other hand, in this gas engine, since the fuel gas amount Q is supplied in a substantially fixed amount, the engine speed is substantially stabilized even at the lean limit. Therefore, the ignition advance value θIG can be retarded while maintaining the engine rotation in a stable state, and the engine output can be continuously and stably controlled even in the low output range.

FIG. 9 shows the excess air ratio λ and the ignition advance value θIG.
FIG. 6 is a characteristic diagram showing the relationship between the engine output η and the amount of HC discharged.

As is apparent from FIG. 9, until the lean limit region (excess air ratio λ = 1.6) indicated by the point A, the ignition timing is controlled by the optimum ignition advance value θIGY while the flow rate of the fuel gas is controlled. The engine output is controlled by the air-fuel ratio control, and after the air-fuel ratio (excess air ratio λ) reaches the lean limit range, the ignition timing is advanced and retarded to stabilize the engine rotation even in the low output range. The engine output can be controlled while being maintained, and the output variable range of the engine 1 can be continuously expanded from the no-load state to the maximum output. Moreover, since the combustion is performed without any trouble, it is possible to prevent the emission amount of HC in the low output region from extremely increasing, as indicated by the broken line.

As described above, in the control system of the present gas engine, the engine output can be controlled by increasing or decreasing the fuel gas amount Q during normal operation, and the ignition timing can be adjusted when the air-fuel ratio reaches the lean limit range. By retarding by a predetermined angle, the engine output can be gradually reduced while maintaining the air-fuel ratio in that state (for example, λ = 1.6). As a result, the engine speed NE can be feedback-controlled to the set speed to maintain stable and substantially constant speed operation, and the engine output can be stably controlled even in the low output range. Moreover, at the same air-fuel ratio, the later the ignition timing is, the more the NOx emission is reduced, so that the NOx can be reduced in the light load operation region. Therefore,
To control the engine output over a wide range from the no-load state to the maximum output state while avoiding irregular combustion in the low output range while performing stable nearly constant speed operation by feedback controlling the engine speed to the set rotational speed. You can

Further, since the above-mentioned control is performed by the control valve 7 (electromagnetic proportional valve) capable of adjusting the supply pressure, it is not necessary to adjust the supply pressure via the pressure regulator unlike the conventional case.
Therefore, the pressure regulator can be omitted, and the device can be made compact. In addition, since the gas nozzle 9 is detachable, even if the gas type is changed, the gas nozzle 9 can be replaced with a gas nozzle 9 having a nozzle diameter suitable for the gas type, and the above-described control can be performed for various gas types. Can be executed.

The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the LAF sensor 35 detects the oxygen concentration to calculate the excess air ratio λ, but the intake air amount is substantially constant because the intake air amount is not controlled by the throttle valve. The excess air ratio λ can be estimated from the fuel gas amount Q and the engine speed NE, and the LAF sensor 35 may be omitted. Further, although advance / retard control of the ignition timing is performed based on the presence or absence of irregular combustion in step S12, the lean limit of the engine 1 is estimated from the excess air ratio λ, and the ignition timing is increased from the air-fuel ratio immediately before the lean limit. It is also possible to control the engine output by retarding the ignition timing. Therefore, it is possible to omit the irregular combustion determination and the ignition timing advance / retard control and substitute the ignition timing map as shown in FIG.

[0057]

As described above in detail, according to the present invention, the supply pressure can be controlled by controlling the current supplied to the control valve (electromagnetic proportional valve) without depending on the fuel gas supply source pressure. Since it is possible to control the engine output over a wide range without being affected by fluctuations in the supply pressure without using a pressure regulator, it is not necessary to use a throttle valve for controlling the intake air amount. The throttle valve can be eliminated, and the size and simplification of the device can be significantly reduced.

Further, since the fuel gas is injected from the detachable gas nozzle, when changing the type of gas such as LPG to LBG, it is possible to deal with it by simply changing the diameter of the nozzle, that is, the nozzle unit. It is possible to deal with various kinds of gas promptly.

Further, according to the present invention, in the air-fuel ratio control, the engine output in the low output range is controlled by advancing and retarding the ignition timing even in the region exceeding the lean limit where irregular combustion occurs. Therefore, the output controllable range of the engine can be greatly expanded from the no-load state to the maximum output state.

Further, since the combustion state can be maintained even in the low output region of the engine, the emission amount of the unburned gas component does not extremely increase, and deterioration of the exhaust purification characteristic in the low output region is avoided as much as possible. can do.

Further, even in the low output range, the engine speed is stabilized and engine vibration can be suppressed.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a gas engine according to the present invention.

FIG. 2 is a sectional view showing a control valve (electromagnetic proportional valve).

FIG. 3 is a diagram showing a method of detecting a combustion state of a gas engine.

FIG. 4 is a characteristic diagram showing a relationship between an engine output and an amount of discharged HC when the engine output is controlled only by air-fuel ratio control.

FIG. 5 is a characteristic diagram showing a relationship between an ignition advance value θIG and an engine output η.

FIG. 6 is a flowchart of a gas amount control routine.

FIG. 7 is a θIGY map for calculating an optimum ignition advance value θIGY.

FIG. 8 is a flowchart of an ignition timing control routine.

FIG. 9 is a characteristic diagram showing the relationship between the excess air ratio λ, the ignition advance value θIG, the engine output η, and the amount of HC discharged.

[Explanation of symbols]

1 gas engine 7 control valve (electromagnetic proportional valve) 8 ECU (ignition timing calculation means, air-fuel ratio control means,
Ignition timing correction means, combustion state determination means, lean limit determination means) 9 gas nozzle 12 valve housing 13 movable valve 14 excitation part 17 diaphragm (pressure adjustment mechanism) 21 diaphragm pressing plate (pressure adjustment mechanism) 29 CRK sensor (operating state detection means) , Rotational speed detection means) 34 LAF sensor (operating state detection means)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location F02D 41/04 325 45/00 362 J F02M 21/06 F F02P 5/15

Claims (6)

[Claims] 1. A control system for a gas engine, wherein a fuel gas supplied through a control valve is mixed with air and supplied to an engine, wherein a gas nozzle for fuel gas injection is removably arranged downstream of the control valve. The control valve is provided with an electromagnetic proportional valve that controls the supply pressure of the fuel gas according to the magnitude of the energizing current without depending on the supply source pressure of the fuel gas. Gas engine control device. 2. The electromagnetic proportional valve is a movable valve that adjusts a flow rate of a fuel gas, a valve housing having the movable valve therein, and a valve housing that is connected to the valve housing to control the operation of the movable valve. 2. The control device for a gas engine according to claim 1, further comprising: an exciting unit for controlling the supply pressure, and the movable valve having a pressure adjusting mechanism for adjusting the supply pressure. 3. An air-fuel ratio control means for controlling an air-fuel ratio of an air-fuel mixture according to a gas amount of the fuel gas controlled by the control valve, an operation state detection means for detecting an operation state of the gas engine, and the operation. Ignition timing calculation means for calculating the ignition timing of the gas engine based on the detection result of the state detection means, and correcting the ignition timing when the air-fuel ratio is below a predetermined value and in a lean limit state. 3. The control device for a gas engine according to claim 1, further comprising an ignition timing correction means for controlling the engine output according to the above. 4. The gas engine control device according to claim 1, wherein a throttle valve for controlling an intake air amount is not arranged in an intake system of the gas engine. 5. The operating state detection means includes at least rotation speed detection means for detecting an engine rotation speed,
A combustion state determination unit that determines the combustion state of the gas engine based on the amount of change in engine speed detected by the rotation number detection unit, and the air-fuel ratio is the predetermined value based on the determination result of the combustion state determination unit. 5. The control apparatus for a gas engine according to claim 4, further comprising a lean limit determination means for determining whether or not the value is equal to or less than a value. 6. The ignition timing correction means is a delay angle correction means for retarding the ignition timing, and the engine output is reduced as the ignition timing is retarded. Item 5. A gas engine control device according to item 5.