JP3291012B2 - Gas fuel engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gaseous fuel engine using a gaseous fuel such as hydrogen gas.

[0002]

2. Description of the Related Art In recent years, gas fuel engines using a combustible gas such as hydrogen gas as fuel have been developed.
When gaseous fuel is used, its volume ratio is much higher than that of gasoline, and hydrogen gas, etc. has a higher combustion speed than gasoline. Countermeasures are required in terms of controlling the supply amount and preventing backfire and premature ignition.

As a conventional gaseous fuel engine of this type,
For example, in Japanese Patent Publication No. 58-36172, a passage for air intake and a passage for hydrogen gas supply are separately formed, and an intake valve and a hydrogen supply valve are provided respectively. While closing at the bottom dead center, the hydrogen supply valve is opened at the bottom dead center so that the valve opening periods do not overlap, so that hydrogen gas with a large volume ratio does not prevent air intake. While the hydrogen supply valve is open, hydrogen gas is fed into the combustion chamber at a pressure higher than the cylinder internal pressure. In addition, Tokiko 1-2
In the invention disclosed in Japanese Patent No. 3659, an air intake valve for supplying air to the combustion chamber and a fuel intake valve for supplying pressurized gaseous fuel are provided independently, and the fuel intake valve is provided just below the end of the air intake stroke. By opening the valve near the dead center, the gaseous fuel is supplied to the combustion chamber under pressure while ensuring air intake.

According to the invention disclosed in Japanese Patent Application Laid-Open No. 2-86921, in an engine in which hydrogen gas is guided from a fuel passage to a carburetor and supplied to a combustion chamber through an intake manifold, hydrogen gas is supplied to the carburetor and the intake manifold after the engine is stopped. In order to prevent the situation where the backfire occurs at the time of restart due to stagnation, when the engine is turned off, the fuel passage is shut off by the electromagnetic control valve in the fuel passage while the ignition operation of the engine is maintained. ing.

[0005]

SUMMARY OF THE INVENTION The above mentioned Japanese Patent Publication No. Sho 58-3
According to the engines disclosed in Japanese Patent No. 6172 and Japanese Patent Publication No. Hei 1-23659, the supply amount of gaseous fuel is adjusted to match the intake air amount of the engine during normal engine operation. It is difficult to properly control the fuel supply when the engine speed is extremely low and the air flow rate is low compared to normal operation due to poor starting, etc. Unnecessary gas fuel may be supplied.
According to the engine disclosed in Japanese Patent Application Laid-Open No. 2-86921, supply of hydrogen gas is stopped when the engine is stopped due to engine key-off. The engine key is turned on when a poor start-up of the engine speed due to poor engine speed causes the engine to keep running at a very low speed, or when the engine is stopped just before the engine stops when the engine stalls. In some cases, the engine may be running at a significantly lower speed than normal, and in such a case, gaseous fuel is supplied.

If the gaseous fuel is supplied unnecessarily at the time of starting failure, engine stall, etc., the air-fuel ratio shifts, for example, becomes over-rich, so that the air-fuel mixture burns normally in the combustion chamber. Otherwise, there is a possibility that afterburn which burns after flowing into the exhaust system may occur, or backfire may occur due to leakage into the intake system.

In view of the above circumstances, the present invention provides a gaseous fuel which can prevent afterburn or backfire due to improper supply of gaseous fuel at the time of engine start failure or immediately before engine stop at engine stall. The purpose is to provide an engine.

[0008]

In order to achieve the above object, the present invention provides a gaseous fuel engine having gaseous fuel supply means for supplying pressurized gaseous fuel to a cylinder.
Supply air to fuel passages and cylinders that guide gaseous fuel
An intake passage formed separately, the shut-off valve that allows blocking the flow of Oite fuel <br/> charge to the fuel passage in the intake passage in odor
And a venturi section that generates a negative pressure in accordance with the airflow
And the air flow through the intake passage is not less than a predetermined amount.
Close the vent valve so that the vent valve closes when
Mechanically opens and closes the shut-off valve in response to changes in negative pressure from the rear section
A shut-off valve consisting of an actuated pressure-responsive actuator
Moving means .

[0009]

According to the structure of the present invention, when the engine speed becomes extremely low due to engine start failure or engine stall, the air flow rate in the intake passage is a predetermined value which is lower than that during normal operation. As described below, the shutoff valve is closed accordingly, whereby the supply of inappropriate gaseous fuel to the engine is reliably stopped.

Further, the opening and closing operation of the shut-off valve is reliably performed by mechanical control according to the negative pressure of the venturi.

[0011]

An embodiment of the present invention will be described with reference to the drawings.

FIGS. 1 and 2 show an embodiment of a gaseous fuel engine according to the present invention. The engine of this embodiment is a rotary piston engine. In the embodiment,
Hydrogen gas is exemplified as the gaseous fuel.

The overall structure of the rotary piston engine and the fuel supply device is shown in FIG. The rotary piston engine has a cylinder constituted by a rotor housing 1 having a peritrochoid-shaped inner peripheral surface and side housings 2 and 3 located on both sides of the cylinder. A substantially triangular rotor 4 is provided inside the cylinder. Have been placed. In a two-rotor rotary piston engine, front and rear cylinders are formed before and after an intermediate housing (intermediate side housing) 3, and a rotor 4 is disposed inside each cylinder. ing. The rotor 4 is supported by an eccentric shaft 5, and its top is in sliding contact with the inner peripheral surface of the rotor housing 1, thereby defining three working chambers 6 in the cylinder. With the eccentric rotation of the rotor 4, each working chamber 6 changes in volume, and performs an Otto cycle. The rotation of the rotor 4 drives the eccentric shaft 5 to rotate.

An intake port 7 for supplying air is provided in the intermediate housing 3 at a position facing the working chamber in the intake stroke. Air is supplied to the intake port 7 through an intake passage 11.
Is provided with a throttle valve 12 operated by a step motor 13, and an air cleaner (not shown)
An air flow meter or the like for detecting an intake air amount is provided. An exhaust port 14 is formed in the rotor housing 1 facing the working chamber in the exhaust stroke.
An exhaust passage 15 is connected to the exhaust passage 4, and an O2 sensor, a catalyst and the like (not shown) are disposed in the exhaust passage 15.

Further, gas fuel supply means for supplying pressurized gas fuel into the cylinder is provided. In this embodiment, the gaseous fuel supply means has a hydrogen port (gaseous fuel supply port) 8 which opens into the working chamber 6 separately from the intake port 7, and the hydrogen port 8 is connected to the intermediate housing. 3 is arranged so as not to interfere with the intake port 7. The means for supplying hydrogen gas to the hydrogen port 8 includes a fuel passage 21 for guiding hydrogen gas from a metal hydride tank (hereinafter referred to as MH tank) 20 to the engine side. The above MH tank 20
Is provided with a hydrogen storage alloy capable of storing and releasing hydrogen therein, and a passage for filling hydrogen, a cooling water passage, and a heating water passage (not shown) are provided for the MH tank 20, and an engine is provided. By heating the hydrogen storage alloy in the MH tank 20 with the cooling water supplied from the water jacket, hydrogen is released to the fuel passage 21.

In the fuel passage 21, a pressure regulator 22,
A flow regulating valve 23 and a timing valve 24 are provided, and a downstream side of the timing valve 24 is connected to a passage constituting member 25 communicating with the hydrogen port 8. The pressure regulator 22 regulates the pressure of the hydrogen gas supplied from the MH tank 20 to an appropriate pressure, for example, approximately 5 atm (3 to 7 atm). The flow control valve 23 can control the flow rate of the hydrogen gas in the fuel passages 22 and 23 in a stepless manner by using a duty solenoid valve or a proportional solenoid valve.

The timing valve 24 supplies fuel at a predetermined timing in synchronization with the operation of the engine. In this embodiment, as shown in detail in FIG. It is opened and closed by a cam 33 provided on a camshaft 32 for driving a timing valve. The camshaft 32 is rotatably supported by the housing, and a pulley 34 provided at one end thereof is connected to the eccentric shaft 5 via a timing belt 35 so that the camshaft 32 rotates synchronously with the eccentric shaft 5. It has become. Passage component 2 downstream of timing valve 24
Numeral 5 is attached to the intermediate housing 3, and the upstream end of a passage 36 inside the intermediate housing 3 communicates with a passage following the timing valve 24, and the downstream end communicates with the hydrogen port 8.

Further, the fuel passage 21 is provided with a shutoff valve 40 which can shut off the flow of fuel. Also,
In the intake passage 11, a venturi section 41 is provided as a detecting means for detecting an air flow state. The venturi section 41 extracts a negative pressure corresponding to the amount of air flowing through the intake passage 11.

The operating means for operating the shutoff valve 40 according to the negative pressure taken out from the venturi section 41 includes:
A pressure-responsive actuator 42 composed of a diaphragm device is provided. The actuator 42 has a diaphragm 43 connected to the shut-off valve 40 via a rod, and a negative pressure chamber 44 on one side of the diaphragm 43 is connected to a negative pressure introducing passage 45 communicating with the venturi section 41.
And a spring 46 for urging the shutoff valve 40 in the valve closing direction. If the negative pressure of the venturi section 41 is larger than a predetermined value, the shut-off valve 40 is opened, and the negative pressure of the venturi section 41 is equal to or lower than a predetermined value (the intake passage 1).
When the air flow rate becomes equal to or less than a predetermined value, the shut-off valve 40 is closed by the force of the spring 46.

Note that 50 is a control unit (EC
U), and controls the flow control valve 23 in the fuel passage 21. This ECU 50 has a detection signal from a rotation speed sensor 51 for detecting the engine rotation speed,
A detection signal from an accelerator opening sensor 52 for detecting an accelerator opening (accelerator pedal depression amount);
A signal from a pressure sensor 53 that detects the pressure in the fuel passage 21 downstream of the second sensor 2 is input. And the ECU 50
Controls the amount of hydrogen gas supplied to the working chamber by controlling the flow rate control valve 23 according to the engine load and the engine speed. When the engine is turned off, the flow control valve 23 is fully closed.

In the illustrated example, a control signal is also output to the actuator 13 of the throttle valve 12 in order to electrically control the opening of the throttle valve 12 according to the accelerator opening and the like.

FIG. 3 shows a specific example of the opening and closing timings of the intake port 7, the hydrogen port 8, and the timing valve 24. The arrangement and shape of the intake port 7 are such that the intake port 7 is opened and closed by the rotation of the rotor 4 and is opened (indicated by reference numeral IP) during a period from near top dead center to a predetermined time after bottom dead center. Is set. The hydrogen port 8 is also opened and closed by the rotation of the rotor 4, but is opened slightly later than the opening timing of the intake port 7, and then closed during the compression stroke considerably later than the closing timing of the intake port 7 (reference numeral). As shown in the figure, the arrangement and the shape are set. Also, the timing valve 24
Is opened during a part of the opening period of the hydrogen port 8, and the timing is set so that the closing timing of the intake port 7 and the opening timing of the timing valve 24 correspond to each other (the symbol TV is attached). Shown). This timing valve 24
The period during which is open is the hydrogen gas supply period.

According to the apparatus of this embodiment, during normal operation of the engine, the negative pressure of the venturi section 41 is higher than a predetermined value, and the negative pressure is reduced by the actuator 4 of the shut-off valve 40.
By acting on 2, the shutoff valve 40 is kept open. And, according to the operation state, the flow control valve 23
Is controlled, the hydrogen gas is supplied to the working chamber 6 at a predetermined time via the timing valve 24 while the flow rate of the hydrogen gas in the fuel passage 21 is controlled.

In this case, as shown in FIG. 3, the timing is set so that the timing valve 24 is opened and the supply of hydrogen gas is started from the time when the intake port 7 is closed and the intake of air is completed. If so, the intake of air and the supply of hydrogen gas are performed appropriately. That is, if hydrogen gas having a large volume ratio is sucked during the air suction stroke, the inflow of air is likely to be hindered, and there is a concern that backfire may occur due to outflow of hydrogen gas to the intake passage side. This will eliminate such adverse effects, increase the volumetric efficiency of air, and prevent backfire. Further, when a rotary piston engine is adopted as the gaseous fuel engine as in this embodiment, since the periods of the intake stroke and the compression stroke are longer than that of the reciprocating engine, a sufficient air intake period is required, and the supply of hydrogen gas is completed after the end of the intake. , A sufficient hydrogen gas supply period can be secured. Further, according to the rotary piston engine, the hydrogen port 8 can be arranged at a position distant from the spark plug, so that the temperature near the hydrogen port 8 can be kept low, which is advantageous for preventing premature ignition.

When the engine speed becomes extremely low and the air flow rate in the intake passage 11 becomes lower than a predetermined value which is lower than that during normal operation, the negative pressure of the venturi section 41 becomes smaller. , The shut-off valve 40 is closed. Thus, for example, even when an abnormal low rotation state of the engine occurs due to poor starting or engine stall at the time of starting the engine, afterburning in the exhaust passage 15,
Backfire in the intake passage 11 can be prevented.

That is, when the engine key is turned off, the flow control valve 23 is fully closed. However, the engine speed does not rise due to insufficient supply voltage to the starter at the time of starting, or the engine stops when the engine stalls. When the key is on and the engine speed is extremely low, as in the state immediately before, the flow control valve 23 is not closed,
In addition, the amount of air suction becomes extremely small. Under these circumstances, even if the fuel is supplied, it is difficult to normally burn in the working chamber 6, and particularly when the fuel is supplied at a relatively high pressure in the early stage of the compression stroke, the air-fuel mixture becomes overlitch due to a control error or the like. easy. In this case, the shut-off valve 40 that operates according to the amount of air flowing through the intake passage 11 is closed, so that the supply of hydrogen gas is reliably stopped, and the hydrogen gas flows into the working chamber 6. By preventing the over-rich state from occurring, the above-described afterburn and backfire are prevented.

If the shut-off valve 40 is provided downstream of the flow control valve 23 in the fuel passage 21, hydrogen gas remaining in the fuel passage 21 downstream of the flow control valve 23 flows into the working chamber 6. Is also suppressed.

Further, in this embodiment, the opening / closing operation of the shut-off valve 40 is mechanically controlled by using the actuator 42 which uses the Venturi negative pressure itself as a detection signal of the air flow state as a driving source. Even in the event of a system failure, the operation of the drive system of the shut-off valve 40 is not hindered.

The configuration of the gaseous fuel supply system is not limited to the above-described embodiment. For example, the gaseous fuel supply system may be configured such that hydrogen gas or the like is pressurized into the cylinder during the intake stroke or pressurized into the intake passage. Also, the present invention can be applied.
The gaseous fuel is not limited to hydrogen gas, and may be city gas or the like in which hydrogen and methane are mixed.

The present invention can be applied not only to a rotary piston engine but also to a reciprocating engine.

[0031]

According to the present invention, a shut-off valve is provided in a fuel passage for guiding pressurized gaseous fuel, and the shut-off valve is closed when the air flow rate in the intake passage is equal to or less than a predetermined value. Since the valve actuating means is provided, when the air flow becomes extremely small immediately before the engine at the time of engine start failure or engine stall, supply of unnecessary gaseous fuel to the cylinder is reliably stopped. . For this reason,
It is possible to prevent afterburn in the exhaust system and backfire in the intake system due to improper supply of gaseous fuel.

Further, a negative pressure corresponding to the air flow rate in the intake passage
And the pressure from this venturi
The above-mentioned shut-off valve is
If mechanical control of the
In the event of a system failure, etc., this may interfere with the operation of the shut-off valve.
As a result, reliability can be ensured.

In particular, the gaseous fuel supply means is connected to the intake port.
Is gas after the end of air intake from separate gas fuel supply port
When fuel is supplied into the cylinder,
Supply gaseous fuel during operation without disturbing air intake
Gas fuel at relatively high pressures
In relation to being supplied, the amount of air circulation as above
If the gaseous fuel is supplied when the amount is extremely low, the mixture will turn off.
Said that after-burn etc. easily occur
Problem can be solved.

Further, downstream from the flow control valve in the fuel passage.
If the above-mentioned shut-off valve is arranged, the air flow rate is less than a predetermined value.
Is reached, the fuel flows into the fuel passage downstream of the flow control valve.
It also suppresses the remaining hydrogen gas from flowing into the working chamber.
Afterburn etc. can be prevented more reliably.

[Brief description of the drawings]

FIG. 1 is an explanatory view of the overall structure of a gaseous fuel engine according to one embodiment of the present invention.

FIG. 2 is an enlarged partial cross-sectional view of a main part.

FIG. 3 is a diagram showing an example of each opening / closing timing of an intake port, a hydrogen port, and a timing valve.

FIG. 4 is an explanatory view of the overall structure of a gaseous fuel engine according to another embodiment of the present invention.

FIG. 5 is a flowchart of a successful operation by the ECU in the embodiment of FIG. 4;

[Explanation of symbols]

 7 Intake port 8 Hydrogen port 11 Intake passage 21 Fuel passage 23 Flow control valve 40 Shutoff valve 41 Venturi part 42 Actuator 50 ECU

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Eiji Takano 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References JP-A-51-124707 (JP, A) JP-A-5 -71421 (JP, A) JP-A-4-171258 (JP, A) JP-A-3-85359 (JP, A) JP-A-64-32058 (JP, A) (58) Fields investigated (Int. . ^7, DB name) F02D 19/02 F02M 21/02

Claims (1)

(57) [Claims] 1. A gaseous fuel engine having gaseous fuel supply means for supplying pressurized gaseous fuel to a cylinder.
Supply air to fuel passages and cylinders that guide gaseous fuel
An intake passage formed separately generated and shut-off valve that allows blocking the flow of Oite fuel in the fuel passageway, a negative pressure corresponding to the air flow amount during the intake passage
A venturi section, and when the amount of air flowing through the intake passage is equal to or less than a predetermined amount,
The negative pressure from the venturi section is
Pressure response that mechanically opens and closes the shut-off valve in response to changes
Provided with shut-off valve actuation means
And a gaseous fuel engine.