JPH05214937A - Gas fuel engine - Google Patents

Abstract

PURPOSE:To prevent afterburn or backfire due to an inappropriate feed of gas fuel at the time of unsatisfactory start of an engine or immediately before an engine stop at the time of engine stall in the gas fuel engine pressurized and fed with the gas fuel such as hydrogen gas to a cylinder. CONSTITUTION:A gas fuel engine is provided with a cutoff valve 40 downstream of a flow adjusting valve 23 in a fuel passage 21. It is also provided with a means detecting the air flow state of an intake passage 11 such as a Venturi section 41 and a means closing the cutoff valve 40 when the air flow quantity of the intake passage 11 becomes a preset value or below such as a pressure- responsive actuator 42.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, a gas fuel engine using a combustible gas such as hydrogen gas as a fuel has been developed.
When gas fuel is used, its volume ratio is remarkably larger than that of gasoline, and because hydrogen gas has a unique combustion speed that is faster than that of gasoline, it is necessary to secure an air intake amount and gas fuel. Measures are required to control the supply amount and prevent backfire and pre-ignition.

As a conventional gas fuel engine of this type,
For example, in Japanese Patent Publication No. 58-36172, a passage for intake of air and a passage for supply of hydrogen gas are separately formed, and an intake valve and a hydrogen supply valve are provided respectively, and the intake valve is provided. While closing at the bottom dead center, the hydrogen supply valve is opened at the bottom dead center so that the two valve opening periods do not overlap, so that hydrogen gas with a large volume ratio does not interfere with the intake of air. 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, Japanese Patent Fair 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 in the vicinity of the dead center, the gaseous fuel is pressurized and supplied to the combustion chamber while ensuring the air intake.

Further, according to the invention disclosed in Japanese Patent Laid-Open No. 2-86921, in an engine which guides hydrogen gas from a fuel passage to a carburetor and supplies it to a combustion chamber through an intake manifold, hydrogen gas is introduced into the carburetor and the intake manifold after the engine is stopped. In order to prevent a situation where backfire is caused by staying and restarting, when the engine key is off, the fuel passage is shut off by the electromagnetic control valve in the fuel passage while maintaining the ignition operation of the engine. ing.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
According to the engines disclosed in Japanese Patent No. 6172 and Japanese Patent Publication No. 1-23659, the supply amount of gaseous fuel is adjusted to match the intake air amount of the engine during normal engine operation. When the engine speed is extremely low compared to during normal operation due to poor starting, etc., and the amount of air flow is small, it becomes difficult to control the fuel supply amount properly and the engine does not operate normally. It is possible that gaseous fuel will be supplied unnecessarily.
Further, according to the engine disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2-86921, the supply of hydrogen gas is stopped when the engine is stopped by the engine key-off. However, even in this engine, for example, the starter due to insufficient battery voltage at the time of starting the engine. The engine key is on when there is a starting failure such that the engine speed rises poorly and the engine speed continues to be extremely low, or when the engine is about to stall during operation and the engine is about to stop. Moreover, the engine may be in a state of rotating at a remarkably lower rotation speed than in the normal state, and in such a case, the gaseous fuel is supplied.

When the gaseous fuel is unnecessarily supplied during the engine start failure, engine stall, etc. as described above, the air-fuel ratio shifts, for example, becomes overrich, so that the air-fuel mixture normally burns in the combustion chamber. Without doing so, there is a possibility that afterburn that occurs after flowing out to the exhaust system may occur or that backfire may occur due to leakage to the intake system.

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

[0008]

In order to achieve the above object, a first invention (claim 1) is a gas fuel provided with a gas fuel supply means for supplying a pressurized gas fuel to a cylinder. In the engine, a shutoff valve that shuts off the flow of fuel is provided in the fuel passage that guides the gaseous fuel, and
Detecting means for detecting the air circulation state of the intake passage for supplying air into the cylinder, and shutoff for closing the shutoff valve when the air circulation amount of the intake passage is below a predetermined value according to the output of the detecting means. And valve actuating means.

According to a second invention (claim 2), in the first invention, the gaseous fuel supply means has a gaseous fuel supply port opened in the cylinder separately from an intake port for air intake. The gas fuel is supplied into the cylinder after the end of the air intake from the intake port.

According to a third invention (claim 3), in the first or second invention, a flow rate adjusting valve for controlling a fuel supply amount according to an operating state is provided in the fuel passage, and the flow rate adjusting valve is provided. The shutoff valve is arranged further downstream.

According to a fourth aspect of the present invention (claim 4), in any one of the first to third aspects of the invention, the detecting means comprises a venturi portion for generating a negative pressure according to the amount of air flowing through the intake passage, The means comprises a pressure-responsive actuator that mechanically opens and closes the shutoff valve in response to a change in pressure from the venturi portion.

[0012]

According to the structure of the first aspect of the present invention, when the engine speed becomes extremely low due to engine start failure, engine stall, or the like, the air flow rate in the intake passage is lower than that during normal operation. When the value becomes equal to or less than the predetermined value and the shutoff valve is closed accordingly, the supply of the improper gaseous fuel to the engine is surely stopped.

According to the second aspect of the invention, the fuel supply means supplies the fuel at a relatively high pressure after the end of the air intake so as not to hinder the air inflow during the air intake stroke. In connection with the difficulty of accurately controlling the fuel supply when the air volume is low,
In the above case, the situation where the gaseous fuel is supplied under the inaccurate fuel control situation is avoided.

According to a third invention, in the above case,
The flow of gaseous fuel into the combustion chamber from a portion downstream of the flow rate adjusting valve in the fuel passage is suppressed.

According to the fourth aspect of the present invention, the opening / closing operation of the shut-off valve is reliably performed by the mechanical control according to the Venturi negative pressure.

[0016]

Embodiments of the present invention will be described with reference to the drawings.
1 and 2 show an embodiment of a gas fuel engine according to the present invention, and the engine of this embodiment is a rotary piston engine. Further, in the embodiment, hydrogen gas is exemplified as the gaseous fuel.

The overall structure of the rotary piston engine and fuel supply system is shown in FIG. The rotary piston engine has a cylinder composed of a rotor housing 1 having a peritrochoidal inner peripheral surface and side housings 2 and 3 located on both sides thereof, and a substantially triangular rotor 4 inside thereof. It is arranged. In a two-rotor rotary piston engine, a front side cylinder and a rear side cylinder are formed in front of and behind the intermediate housing (intermediate side housing) 3, and a rotor 4 is arranged inside each of them. ing. The rotor 4 is supported by an eccentric shaft 5, the top portion of which is in sliding contact with the inner peripheral surface of the rotor housing 1, and three working chambers 6 are defined in the cylinder. With the eccentric rotation of the rotor 4, the volume of each working chamber 6 changes, and the Otto cycle is performed. The eccentric shaft 5 is rotationally driven by the rotation of the rotor 4.

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 the intake passage 11, and the 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 the 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 O ₂ sensor, a catalyst and the like (not shown) are arranged in the exhaust passage 15.

Further, a gas fuel supply means for supplying the pressurized gas fuel into the cylinder is provided. In the present embodiment, this gaseous fuel supply means has a hydrogen port (gas fuel supply port) 8 that opens into the working chamber 6 separately from the intake port 7, and this hydrogen port 8 is 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 that guides hydrogen gas from a metal hydride tank (hereinafter referred to as MH tank) 20 to the engine side. The MH tank 20
Is equipped with a hydrogen storage alloy capable of storing and releasing hydrogen therein, and a passage for hydrogen filling, a cooling water passage and a heating water passage (not shown) are provided for the MH tank 20. The hydrogen storage alloy in the MH tank 20 is heated by the cooling water supplied from the water jacket, so that hydrogen is released into the fuel passage 21.

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

The timing valve 24 supplies fuel at a predetermined timing in synchronism with the operation of the engine. In this embodiment, a poppet valve 31 is provided as shown in detail in FIG. The opening / closing operation is performed by a cam 33 provided on the timing valve driving cam shaft 32. The cam shaft 32 is rotatably supported by the housing, and a pulley 34 provided at one end of the cam shaft 32 is linked to the eccentric shaft 5 via a timing belt 35 so that the cam shaft 32 rotates synchronously with the eccentric shaft 5. It has become. Passage forming member 2 downstream of the timing valve 24
5 is attached to the intermediate housing 3, and the upstream end side of the passage 36 therein communicates with the passage continuing to the timing valve 24, and the downstream end side communicates with the hydrogen port 8.

Further, the fuel passage 21 is provided with a shutoff valve 40 capable of shutting off the flow of fuel. Also,
In the intake passage 11, a venturi portion 41 is provided as a detection means for detecting the air circulation state. By the venturi portion 41, a negative pressure according to the amount of air flowing through the intake passage 11 is taken out.

As an operating means for operating the shutoff valve 40 in accordance with the negative pressure taken out from the venturi portion 41,
A pressure-responsive actuator 42 composed of a diaphragm device is provided. The actuator 42 has a diaphragm 43 connected to the shutoff valve 40 via a rod, and a negative pressure chamber 44 on one side of the diaphragm 43 leads to the venturi portion 41.
And a spring 46 for urging the shutoff valve 40 in the valve closing direction. If the negative pressure in the venturi portion 41 is higher than a predetermined value, the shutoff valve 40 is opened, and the negative pressure in the venturi portion 41 is equal to or lower than the predetermined value (intake passage 1
The shut-off valve 40 is closed by the force of the spring 46 when the air circulation amount of 1 becomes a predetermined value or less).

Reference numeral 50 is a control unit (EC
U), which controls the flow rate adjusting valve 23 in the fuel passage 21 and the like. The ECU 50 is provided with a detection signal from a rotation speed sensor 51 for detecting the engine rotation speed,
Detection signal from accelerator opening sensor 52 for detecting accelerator opening (accelerator pedal depression amount), pressure regulator 2
Signals from a pressure sensor 53 that detects the pressure in the fuel passage 21 downstream of 2 are input. And the ECU 50
Controls the flow rate adjusting valve 23 according to the engine load, the engine speed, etc. to control the amount of hydrogen gas supplied to the working chamber. When the engine key is off, the flow rate adjusting valve 23 is fully closed.

In the illustrated example, since the opening degree of the throttle valve 12 is electrically controlled according to the accelerator opening degree or the like, a control signal is also output to the actuator 13 of the throttle valve 12.

FIG. 3 shows a specific example of opening / closing timings of the intake port 7, hydrogen port 8 and timing valve 24. The intake port 7 is opened and closed by the rotation of the rotor 4, and its arrangement and shape are such that the intake port 7 is opened (indicated by reference numeral IP) during a period from near the top dead center to a predetermined time after the bottom dead center. It is set. Further, the hydrogen port 8 is also opened and closed by the rotation of the rotor 4, but after being opened slightly later than the opening timing of the intake port 7, it is closed in the middle of the compression stroke which is considerably later than the closing timing of the intake port 7 (reference numeral). The layout and shape are set as shown in FIG. 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 corresponds to the opening timing of the timing valve 26 (denoted by the symbol TV). To show). The period in which the timing valve 26 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 portion 41 is higher than a predetermined value, and the negative pressure is the actuator 4 of the shutoff valve 40.
By acting on 2, the shutoff valve 40 is kept in the open state. Then, the flow rate adjusting valve 23 according to the operating state.
Is controlled, the hydrogen gas flow rate in the fuel passage 21 is controlled, and the hydrogen gas is supplied to the working chamber 6 at a predetermined time via the timing valve 24.

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. In this case, inhalation of air and supply of hydrogen gas are appropriately performed. In other words, if hydrogen gas with a large volume ratio is taken in during the air intake process, the inflow of air is likely to be hindered and backfire may occur due to the outflow of hydrogen gas to the intake passage side. By doing so, such adverse effects are removed, the volumetric efficiency of air is enhanced, and backfire is prevented. Further, when the rotary piston engine is adopted as the gas fuel engine as in this embodiment, the intake stroke and the compression stroke are longer than those of the reciprocating engine, so that the air intake period is sufficiently long and the hydrogen gas is supplied after the intake is completed. It is possible to secure a sufficient hydrogen gas supply period while performing the above. Further, according to the rotary piston engine, since the hydrogen port 8 can be arranged at a position away from the spark plug, the temperature near the hydrogen port 8 can be kept low, which is also advantageous in preventing premature ignition.

Further, 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 decreases. The shutoff valve 40 is closed. As a result, for example, afterburn in the exhaust passage 15 or even when an abnormally low engine speed is generated due to a start failure or engine stall at engine startup,
Backfire in the intake passage 11 can be prevented.

That is, when the engine key is turned off, the flow rate adjusting valve 23 is fully closed, but the engine speed does not rise because the supply voltage to the starter is insufficient at the time of starting, or the engine stops at the time of engine stall. When the engine is in the key-on state and the engine speed is extremely low as in the immediately preceding state, the flow rate adjusting valve 23 does not close,
In addition, the amount of air taken in is extremely small. Under such a situation, even if the fuel is supplied, it is difficult to normally combust in the working chamber 6. Especially, when the fuel is supplied with a relatively high pressure in the early stage of the compression stroke, the air-fuel mixture becomes overlit due to a control error or the like. easy. In this case, the shutoff valve 40 that operates according to the amount of air flowing in 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 situation of becoming the overrich state, the above-mentioned afterburn and backfire are prevented.

If the shutoff valve 40 is provided in the fuel passage 21 downstream of the flow rate adjusting valve 23, hydrogen gas remaining in the fuel passage 21 downstream of the flow rate adjusting valve 23 will flow into the working chamber 6. Is also suppressed.

Further, in the present embodiment, since the actuator 42 driven by the Venturi negative pressure itself as a detection signal of the air circulation state is used as the drive source to mechanically control the opening / closing operation of the shutoff valve 40, the electric Even when the system fails, the operation of the drive system of the shutoff valve 40 is not hindered.

FIG. 4 shows another embodiment of the present invention. In this embodiment, the opening / closing operation of the shutoff valve 40 is electrically controlled. That is, the negative pressure sensor 61 that converts the negative pressure of the venturi portion 41 provided in the intake passage 11 into an electric signal is provided, and the signal of the negative pressure sensor 61 is input to the ECU 50, while the fuel passage 21 is opened and closed. An electric actuator 60 including a solenoid is provided for the shutoff valve 40. And the ECU
A signal from the negative pressure sensor is compared with a threshold value by 50, and a control signal for opening and closing the shutoff valve 40 is output to the actuator 60 accordingly.

FIG. 5 is a flow chart showing an example of control according to this embodiment. In this flowchart, first, the engine speed, accelerator opening, intake pressure (negative pressure in the venturi portion), etc. are read as input information in step S1, and the air circulation amount Va is calculated in step S2. Then, in step S3, the air circulation amount V
It is determined whether or not a is less than or equal to a preset threshold V,
If it is less than or equal to the threshold value V, the control signal for closing the shutoff valve 40 in the valve closing state is given in step S4.
It is output to 0.

Also in this embodiment, the air flow amount in the intake passage 11 is reduced to a predetermined value or lower than the value during normal operation by the control according to the determination by the ECU 50 based on the signal from the negative pressure sensor 61. At this time, the shutoff valve 40 of the fuel passage 21 is closed. Therefore, afterburning or backfire is prevented by stopping the supply of hydrogen gas to the working chamber 6 when the air flow rate becomes extremely small due to engine malfunction or engine stall. The same as in the first embodiment.

The structure of the gas fuel supply system is not limited to the above embodiment, and for example, hydrogen gas or the like is pressurized and supplied into the cylinder during the intake stroke, or is pressurized and supplied to the intake passage. Also, the present invention can be applied.
The gaseous fuel is not limited to hydrogen gas, but may be city gas or the like in which hydrogen and methane are mixed.

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

[0038]

According to the first aspect of the present invention, the shutoff valve is provided in the fuel passage for guiding the pressurized gaseous fuel, and the above-mentioned means is provided in accordance with the output of the detection means for detecting the air circulation state of the intake passage. Since the shut-off valve operating means for closing the shut-off valve is provided when the air flow rate in the intake passage is less than or equal to a predetermined value, the air flow rate is extremely small immediately before the engine at the time of engine start failure or engine stall. When this happens, the supply of unnecessary gaseous fuel to the cylinder is surely stopped. Therefore, afterburn in the exhaust system and backfire in the intake system due to improper supply of gaseous fuel can be prevented.

Particularly, as described in claim 2, when the gas fuel supply means is adapted to supply the gas fuel into the cylinder after the end of the air suction from the gas fuel supply port different from the intake port, the normal operation is performed. While making it possible to supply gaseous fuel without hindering the intake of air,
Due to the fact that the gaseous fuel is supplied at a relatively high pressure, when the gaseous fuel is supplied when the air flow amount is extremely small as described above, the air-fuel mixture becomes overrich and the above-mentioned afterburn is likely to occur. That problem can be solved.

When the shut-off valve is arranged downstream of the flow rate adjusting valve in the fuel passage as described in claim 3, the flow rate adjusting valve is set when the air flow rate becomes a predetermined value or less. It is also possible to prevent hydrogen gas remaining in the fuel passage on the further downstream side from flowing into the working chamber, and to prevent afterburn and the like more reliably.

Further, as described in claim 4, the shutoff valve as described above is provided by the venturi portion which generates a negative pressure according to the air flow rate in the intake passage and the pressure responsive actuator which receives the pressure from the venturi portion. If the control is performed mechanically, the reliability of the shut-off valve can be ensured even when the electric system fails or the like.

[Brief description of drawings]

FIG. 1 is an overall structural explanatory view of a gas fuel engine according to an embodiment of the present invention.

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

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

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

5 is a flowchart of control by an ECU in the embodiment of FIG.

[Explanation of symbols]

 7 Intake Port 8 Hydrogen Port 11 Intake Passage 21 Fuel Passage 23 Flow Control Valve 40 Shutoff Valve 41 Venturi Section 42 Actuator 50 ECU

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Eiji Takano 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Motor Corporation

Claims (4)

[Claims] 1. A gas fuel engine comprising a gas fuel supply means for supplying a pressurized gas fuel to a cylinder, and a shutoff valve for shutting off the flow of the fuel is provided in a fuel passage for guiding the gas fuel. Detection means for detecting the air circulation state of the intake passage for supplying air into the cylinder;
A gas fuel engine, comprising: a shutoff valve actuating means for closing the shutoff valve when the air flow rate in the intake passage is equal to or less than a predetermined value in accordance with the output of the detection means. 2. The gaseous fuel supply means has a gaseous fuel supply port that opens into the cylinder separately from an intake port for intake of air, and supplies the gaseous fuel into the cylinder after completion of intake of air from the intake port. The gas fuel engine according to claim 1, wherein 3. The gas fuel engine according to claim 1, wherein a flow rate adjusting valve for controlling a fuel supply amount according to an operating state is provided in the fuel passage, and the shutoff valve is arranged downstream of the flow rate adjusting valve. 4. The detecting means comprises a venturi portion for generating a negative pressure according to the amount of air flowing through the intake passage, and the operating means mechanically opens and closes the shutoff valve in response to a change in pressure from the venturi portion. The gas fuel engine according to any one of claims 1 to 3, comprising a pressure responsive actuator that operates.