JPH0714135U - Air-fuel ratio controller for compressed natural gas engine - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to an air-fuel ratio control device for a compressed natural gas engine, and an object thereof is to obtain a uniform or arbitrary air-fuel ratio. A gas mixer for mixing intake air and compressed natural gas fuel is provided with an auxiliary fuel supply bypass passage for bypassing the gas mixer, and auxiliary fuel amount adjusting means is provided in the fuel supply bypass passage, and intake air amount detecting means, Based on the signals from the engine speed detection means and the air-fuel ratio detection means, the amount of compressed natural gas fuel mixed from the characteristics of the gas mixer is calculated backward, and the corrected amount of compressed natural gas fuel to obtain the required air-fuel ratio is calculated. The amount of compressed natural gas fuel is increased and corrected by the auxiliary fuel amount adjusting means.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention adjusts the compressed natural gas fuel supplied through the fuel supply passage according to the intake air amount by the gas mixer in the intake air supply passage, and mixes it into the cylinder according to the throttle opening. The present invention relates to an air-fuel ratio control device for a compressed natural gas engine that controls the air, determines the injection amount according to the intake mixture, and controls the air-fuel ratio.

[0002]

[Prior art]

 Conventionally, the air-fuel ratio in a gasoline engine has been determined by the fuel injection amount in a fuel injection type engine and the intake amount of fuel mixed with air in a carburetor type engine according to the intake air amount.

However, in the compressed natural gas engine, a gas mixer is provided in the intake air supply passage, and the compressed natural gas fuel supplied through the fuel supply passage is metered according to the intake air amount passing through the intake air supply passage. To do.

Then, the air-fuel mixture supplied into the cylinder is controlled by the opening degree of the throttle to increase / decrease the rotation speed of the engine. The rotation speed of the engine also increases / decreases depending on the rotation load of the engine. .

As described above, in the compressed natural gas engine, the air-fuel ratio is determined by the mechanical characteristics of the gas mixer. As a fuel supply device for such a gas engine, the technique described in Japanese Utility Model Laid-Open No. 60-90533 and the technique described in Japanese Utility Model Laid-Open No. 60-92742 are disclosed as prior art.

[0006]

[Problems to be solved by the device]

 Since the mixing characteristics of natural gas in a compressed natural gas engine as described above are determined by the mechanical characteristics of the gas mixer, depending on the engine speed and throttle conditions, a uniform air-fuel ratio or an arbitrary air-fuel ratio may be used. There was a point that the air-fuel ratio could not be obtained.

It is an object of the present invention to obtain a uniform air-fuel ratio or an arbitrary air-fuel ratio for achieving the above-mentioned problems of conventional air-fuel ratio control in a compressed natural gas engine.

[0008]

[Means for Solving the Problems]

 According to the first aspect of the present invention, the compressed natural gas fuel supplied through the fuel supply passage is metered by the gas mixer in the intake air supply passage, and the cylinder is opened by the throttle opening. In an air-fuel ratio control device for a compressed natural gas engine that controls the air-fuel ratio that controls the air-fuel ratio, controls the air-fuel ratio that is sucked into the air-fuel ratio, and uses an auxiliary fuel supply bypass path that bypasses the gas mixer. The auxiliary fuel metering means is provided in the fuel supply bypass passage, and the compressed natural gas mixed from the characteristics of the gas mixer is mixed based on the signals from the intake air amount detecting means, the engine speed detecting means, and the air-fuel ratio detecting means. The amount of gas fuel is back-calculated to calculate the corrected compressed natural gas fuel amount to achieve the required air-fuel ratio, and the amount of compressed natural gas fuel is increased and corrected by the auxiliary fuel metering means. Characterized by comprising a control unit that.

The invention according to claim 2 is characterized in that the fuel supply bypass passage in the invention according to claim 1 is replaced with an air supply bypass passage, and the compressed natural gas fuel amount is replaced with an intake air amount.

[0010]

[Action]

 In the air-fuel ratio controller for the compressed natural gas engine of the present invention, the corrected compressed natural gas fuel amount for achieving the required air-fuel ratio is calculated, and the compressed natural gas fuel amount is used in claim 1 and the corrected natural gas fuel amount is used in claim 2. If the intake air amount is increased and corrected, a uniform air-fuel ratio or an arbitrary air-fuel ratio can be obtained.

Therefore, if the engine is burned with a three-way catalyst or the NO _x exhaust gas due to the lean fuel is suppressed, a catalytic effect can be obtained, the combustion can be stabilized, and the best in all operating regions. The state is obtained.

[0012]

【Example】

 Next, an embodiment of the invention according to claim 1 will be described below with reference to FIGS.

In this embodiment, compressed natural gas is introduced from the compressed natural gas cylinder 1 into the gas mixer 3 via the pressure reducing valve 2, and the atmosphere is introduced into the gas mixer 3 via the intake air amount sensor 4, Although natural gas and air are mixed, the air-fuel ratio, which represents the mixing ratio of air and natural gas that is the fuel at this time, is determined by the mechanical configuration of the gas mixer 3 and cannot be arbitrarily changed.

In the air-fuel mixture passage 7 from the gas mixer 3 to the intake manifold 6 of the engine 5, there is provided a throttle valve 8 for controlling the rotational speed of the engine 5 by adjusting the flow rate of the air-fuel mixture to the engine 5. The opening of the throttle valve 8 is detected by the slot sensor 9.

The natural gas passage 10 from the pressure reducing valve 2 to the gas mixer 3 and the mixture passage 7 between the gas mixer 3 and the throttle valve 8 have a duty solenoid valve 11 for increasing the amount of compressed natural gas. The fuel supply bypass passage 12 is provided as a bypass for the gas mixer 3.

Further, the engine 5 is provided with a crank angle sensor 13 for detecting the crank angle thereof, and the exhaust manifold 14 of the engine 5 is provided with an air-fuel ratio sensor 15, the intake air amount sensor 4, the throttle Detection values of the sensor 9, the crank angle sensor 13, and the air-fuel ratio sensor 15 are input to the control circuit 16.

The control circuit 16 controls the ignition timing of the spark plug 17 and outputs the duty solenoid valve 11 to control the opening thereof. The control circuit 16 controls the opening degree of the block diaphragm of FIG. In order to perform the operation of, the operation is performed according to the flowchart shown in FIG.

That is, when this flowchart starts, the intake air amount detected by the intake air amount sensor 4 is input in step S1, and the mixing characteristic of the compressed natural gas and the intake air amount by the gas mixer 3 of FIG. 3 is input in step S2. Based on the figure, the mixture amount F _M of compressed natural gas is calculated.

Next, in step S3, the engine speed N of the engine 5 by the crank angle sensor 13 of the engine 5 is input, and in step S4, the opening θ of the throttle valve 8 by the throttle sensor 9 is input. Then, in step S5, the target air-fuel ratio λ is calculated from the target air-fuel ratio map based on the opening θ and the rotation speed N in FIG.

As a result, the required compressed natural gas amount F _R is calculated in step S6 from the target air-fuel ratio λ and the intake air amount in step S1, and the required compressed natural gas amount F is then calculated in step S7. insufficient compressed natural gas quantity from the difference between the mixing amount F _M of _R and compressed natural gas F and _L are calculated.

Next, in step S8, the air-fuel ratio F _F detected by the air-fuel ratio sensor 15 is input, and in step S9, the feedback correction amount F _D due to the difference between the insufficient compressed natural gas amount F _L and the detected air-fuel ratio F _F is calculated. In step S10, the duty solenoid valve 11 is converted to the duty ratio D based on the duty ratio shown in FIG. 3 and the characteristics of the duty solenoid valve 11 with respect to the increase in natural gas. In step S11, the duty solenoid valve 11 is driven with the duty ratio D. This ends the flowchart.

Thus, in this compressed natural gas engine, a uniform or arbitrary air-fuel ratio can be obtained by setting the target air-fuel ratio λ. Next, an embodiment of the invention according to claim 2 will be described below with reference to FIGS. 4 and 5. In this embodiment, between the natural gas passage 10 and the air-fuel mixture passage 7 of the embodiment described above. In place of the fuel supply bypass passage 12 provided with the duty solenoid valve 11 for increasing the compressed gas, a duty solenoid valve 18 for increasing the air amount is provided between the air passage to the gas mixer 3 and the mixture passage 7. The air supply bypass passage 19 is provided, and its configuration is the same except that the flow chart of the control circuit 16 is changed as shown in FIG.

The flow chart of FIG. 5 is not different from the flow chart of FIG. 2 from step S1 to step S5. In step S12, the air-fuel ratio F _F is input from the air-fuel ratio sensor 15, and step S13 is performed. The difference ε with the target air-fuel ratio λ is calculated at.

As a result, in step S14, the air-fuel ratio feedback correction amount PID is calculated by the following equation. F _D = Kpε + K _D ∫ε + K _D Δε After that, the process returns to step S10 of the flowchart of FIG. 2 to perform steps S10 and S11, and this flowchart ends, but in this flowchart, output is performed in step S11. This is the opening degree of the duty solenoid valve 18 for increasing the air amount, and the correction supply amount of air is supplied into the mixture passage 7 to the throttle valve 8.

In the previous example, a uniform or arbitrary air-fuel ratio was obtained by increasing the amount of compressed natural gas, but in the present example, by increasing the amount of intake air, a uniform or arbitrary air-fuel ratio is obtained. I will get it.

[0026]

As described above, according to the present invention, a fuel supply bypass passage is provided from the natural gas passage to the gas mixer, bypassing the gas mixer to reach the air-fuel mixture passage, and a uniform or arbitrary air-fuel ratio is provided. As can be obtained, the control means controls the opening degree of the duty solenoid valve in the fuel supply passage.

Therefore, the air-fuel ratio, which was conventionally determined by the mechanical characteristics of the gas mixer, can be made uniform or the required air-fuel ratio can be obtained even if the engine speed, throttle opening, etc. change. is there.

Further, even if an air bypass passage having a duty solenoid valve for increasing the amount of air is provided between the air passage to the gas mixer and the air-fuel mixture passage to increase the amount of air with respect to the air-fuel mixture, the same result as described above is obtained. It is capable of producing the action and effect.

[Brief description of drawings]

1 is a block diagram of an embodiment of the invention according to claim 1; FIG.

FIG. 2 is a flowchart of a control circuit of the above.

FIG. 3 is a block diaphragm of the control according to the above.

FIG. 4 is a partial view showing a portion different from FIG. 1 of the embodiment of the invention according to claim 2;

FIG. 5 is a flowchart of a control circuit of the above.

[Explanation of symbols]

1 Compressed Natural Gas Cylinder 3 Gas Mixer 4 Intake Air Amount Sensor 5 Engine 7 Mixture Passage 8 Throttle Valve 9 Throttle Sensor 10 Natural Gas Passage 11 Duty Solenoid Valve for Increasing Natural Gas 12 Fuel Supply Bypass Passage 13 Crank Angle Sensor 15 Air Fuel Ratio Sensor 16 Control circuit 18 Duty solenoid valve for increasing air 19 Air supply bypass passage F _D Feedback correction amount F _F Detected air-fuel ratio FL _L Insufficient natural gas F _M Natural gas mixture amount F _R Required natural gas amount N Engine speed θ Throttle opening λ Target air-fuel ratio ε Difference between target air-fuel ratio λ and detected air-fuel ratio F _F

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location F02M 21/02 L (72) Inventor Tatsuji Miyata 1-chome, Ageo City, Saitama Prefecture Nissan Diesel Industry Co., Ltd.

Claims (2)

[Scope of utility model registration request] 1. A gas mixer in an intake air supply passage adjusts the amount of compressed natural gas fuel supplied through a fuel supply passage in accordance with the amount of intake air, and a mixture air intaken into a cylinder by opening a throttle. In an air-fuel ratio control device for a compressed natural gas engine that controls and determines the injection amount according to the intake air-fuel mixture and controls the air-fuel ratio, an auxiliary fuel supply bypass passage that bypasses the gas mixer is provided, and the fuel supply bypass passage Auxiliary fuel metering means is provided in the engine, the compressed natural gas fuel quantity to be mixed is calculated from the characteristics of the gas mixer on the basis of the signals from the intake air quantity detecting means, the engine speed detecting means, and the air-fuel ratio detecting means. A control means for calculating a corrected compressed natural gas fuel amount for achieving the air-fuel ratio and for increasing and correcting the compressed natural gas fuel amount by the auxiliary fuel amount adjusting means is provided. The air-fuel ratio control device for the characteristic compressed natural gas engine. 2. A gas mixer in the intake air supply passage adjusts the amount of compressed natural gas fuel supplied through the fuel supply passage in accordance with the amount of intake air, and the mixture is drawn into the cylinder by opening the throttle. In an air-fuel ratio control device for a compressed natural gas engine that controls and determines the injection amount according to the intake air-fuel mixture, and controls the air-fuel ratio, an air supply bypass passage that bypasses the gas mixer is provided, and the air supply bypass passage is provided. Auxiliary air metering means is provided, and based on the signals from the intake air quantity detecting means, the engine speed detecting means, and the air-fuel ratio detecting means, the amount of compressed natural gas fuel mixed from the characteristics of the gas mixer is calculated backward to obtain the required empty space. A compressed natural gas engine, comprising control means for calculating an intake air amount for achieving a fuel ratio and for increasing and correcting the intake air intake amount by the auxiliary air amount adjusting means. Engine air-fuel ratio control device.