JPH0688542A - Air-fuel ratio controller of hydrogen fueled engine - Google Patents

Abstract

PURPOSE:To prevent the outflow of unburnt hydrogen from occurring as checking the worsening of combustibility by installing a target air-fuel ratio setting means, setting a lean side air-fuel ratio rather than a theoretical air-fuel ratio in all kinetic conditions, and a feed control means controlling a supply of hydrogen and air, respectively. CONSTITUTION:This controller is provided with a target air-fuel ratio setting means 43 which sets a lean side air-fuel ratio rather than a theoretical air-fuel ratio in all driving conditions as a target air-fuel ratio TRGA/F. Also it is provided with a feed control means 44 controlling both hydrogen and air supply quantities QHZ, TQAIR on the basis of the set target air-fuel ratio. In addition, the target air-fuel ratio to be set by the target air-fuel ratio setting means on the basis of an output signal out of the transient driving condition detection means at a time when a transient driving condition is detected, is further compensated to the lean side. Thus, any outflow of unburnt hydrogen into an exhaust pipe is prevented as checking the worsening of combustibility, so the occurrence of afterburning is surely preventable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-fuel ratio control device for controlling the air-fuel ratio of a mixture of air and hydrogen fuel supplied to a combustion chamber in a hydrogen engine.

[0002]

2. Description of the Related Art Generally, in a gasoline engine, the air-fuel ratio of a mixture of gasoline and air supplied to a combustion chamber is changed from the stoichiometric air-fuel ratio to the rich side or the lean side depending on the operating condition to improve the combustibility. Is being improved.

Further, conventionally, in a gasoline engine, it is known that hydrogen is injected and supplied at a low load so that the air-fuel mixture is leaner than the stoichiometric air-fuel ratio to improve fuel consumption and emission ( For example,
See Japanese Patent Laid-Open No. 53-17807).

[0004]

However, in a hydrogen engine that uses hydrogen as a fuel, the concentration is higher than the theoretical air-fuel ratio,
That is, when the rich-side air-fuel mixture is supplied, unburned hydrogen that is not bound to oxygen in the air may flow out to the exhaust pipe, and afterburn may occur in the exhaust pipe or the muffler. Even if the unburned hydrogen is sufficiently diluted in concentration, its combustible limit is much higher than that of gasoline, and therefore there is a peculiarity that afterburn is generated by some heat source such as frictional heat without a fire. Further, when the unburned hydrogen flows out, the unburned hydrogen is released to the atmosphere even if the afterburn does not occur, which causes an increase in the emission. Therefore, it is necessary to surely prevent the outflow of unburned hydrogen from the combustion chamber.

Further, when hydrogen, which is a fuel, is directly injected into the combustion chamber and air is supplied from a port different from that of hydrogen, the air-fuel ratio is set to a predetermined value in a transient operating state in which the operating state changes suddenly such as during sudden acceleration. Even if the air-fuel ratio is controlled to the value, the air-fuel mixture in the combustion chamber may be shifted to the rich side from the air-fuel ratio control value due to the delay of the air supply. That is, in the transient operation state, even if the air throttle valve that adjusts the air amount according to the acceleration operation is suddenly opened, the dead volume in the intake pipe between the air throttle valve and the combustion chamber is adjusted to a predetermined supply pressure. The supply of air to the combustion chamber is delayed by the amount filled up to. Therefore, in the transient operation state, the air-fuel mixture easily shifts to the rich side, and when it shifts to the rich side, the problem of outflow of unburned hydrogen may occur. Moreover, the theoretical air-fuel ratio (about 32) when using hydrogen as fuel is the theoretical air-fuel ratio (1) when using gasoline.
5)), the degree of deviation of the air-fuel ratio to the rich side due to the delay of the air supply is larger in the hydrogen engine than in the gasoline engine. Greater than.

The present invention has been made in view of the above circumstances, and its main purpose is to prevent unburned hydrogen from flowing out to an exhaust pipe while suppressing deterioration of combustibility. Is to prevent the occurrence of. Also,
Another object is to reliably prevent the unburned hydrogen from flowing out to the exhaust pipe due to the air-fuel ratio being shifted to the rich side particularly in a transient operation state where the air-fuel ratio is likely to be shifted.

[0007]

In order to achieve the above object, the invention according to claim 1 is based on the premise that hydrogen is used as fuel, and as shown in FIG. 1, an operation for detecting an operating state of an engine. State detecting means 45 and this operating state detecting means 4
The target air-fuel ratio setting means 43 is provided for setting the air-fuel ratio on the lean side of the theoretical air-fuel ratio as the target air-fuel ratio in all operating states, based on the output signal from 5. The supply control means 44 for controlling the supply amount of at least one of hydrogen and air based on the set target air-fuel ratio is provided.

According to a second aspect of the present invention, in the above-mentioned first aspect of the invention, the target air-fuel ratio setting means is configured to correct the target air-fuel ratio to the lean side, especially in a transient operation state. is there. That is, the transient operating state detecting means 45a for detecting the transient operating state of the engine and the target air-fuel ratio setting means 43 are set based on the output signal from the transient operating state detecting means 45a when the transient operating state is detected. The correction means 43a for further correcting the target air-fuel ratio to the lean side is provided.

[0009]

With the above construction, in the invention according to claim 1,
Since the target air-fuel ratio is set leaner than the stoichiometric air-fuel ratio in all operating conditions, all hydrogen supplied to the combustion chamber is burned, and unburned hydrogen is reliably prevented from flowing out to the exhaust pipe. . Further, since the combustible limit of hydrogen is sufficiently high, sufficient combustibility is maintained.

Further, according to the second aspect of the present invention, in addition to the operation according to the first aspect of the present invention, the target air-fuel ratio is set to be higher than that in other operating states particularly in the transient operating state where the deviation of the air-fuel ratio is likely to occur. Since the correction is made to the lean side, the outflow of unburned hydrogen due to the shift of the air-fuel ratio to the rich side is reliably prevented.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows the overall structure of a hydrogen rotary piston engine (hereinafter, simply referred to as an engine) 1 equipped with an air-fuel ratio control device according to an embodiment of the present invention, which is a so-called two rotors connected in series. A two-rotor rotary piston engine is shown deployed to the left and right.

In the figure, 2 is an intake passage for supplying air to the engine 1, 3 is an exhaust passage for discharging exhaust gas from the engine 1 to the outside, 4 is a metal hydride tank (hereinafter referred to as MH tank) as a hydrogen storage tank. 5 is a hydrogen supply passage for supplying hydrogen gas as a fuel from the MH tank 4 to the engine 1, and 6 is a control unit equipped with an air-fuel ratio control device for controlling the supply of air and hydrogen gas.

The engine 1 has a rotor housing 7 having a peritrochoidal curve as an inner peripheral surface, a pair of side housings (not shown) mounted on both side surfaces of the rotor housing 7, and two insides of the rotor housing 7. A partitioning intermediate housing 8 is provided, and these housings 7 and 8 form two cylinders 9 and 9. A substantially triangular rotor 10 having three inner envelope surfaces is housed in each of the cylinders 9, and three ridge lines of each rotor 10 are respectively provided on the inner circumference of the rotor housing 7 via an apex seal. By airtightly contacting the surfaces, three working chambers 11, 11, ... Are respectively provided between the rotors 10 and the housings 7, 8.
Are sectioned.

Each of the rotors 10 is supported by an eccentric shaft 12 so as to be eccentrically rotatable. The eccentric rotation of each rotor 10 changes the volume of each working chamber 11 so that suction, compression, expansion (explosion) and The eccentric shaft 1 is obtained by performing each exhaust stroke in sequence.
2 is rotationally driven.

The intermediate housing 8 is provided with an intake port 13 and a hydrogen supply port 14 which are open to face the working chamber 11 in the intake stroke of each cylinder 9 and are independent of each other. The intake port 13 is in communication with the downstream end of the intake passage 2, and the hydrogen supply port 14 is in communication with the hydrogen supply passage.

Each of the cylinders 9 is provided in the rotor housing 7.
An exhaust port 15 is formed so as to open toward the working chamber 11 in the exhaust stroke, and the exhaust port 15 communicates with the upstream end of the exhaust passage 3.

Further, the rotor housing 7 is a portion corresponding to the working chambers 11, 11 of the compression and expansion strokes of each cylinder 9, and a pair of leading ignition plugs (IGTs) are provided at leading positions in the rotor rotation direction. -F / L,
IGT-R / L) 16, 16 also has a pair of trailing side ignition plugs (IGT-F / L / L) at the trailing side position.
T, IGT-R / T) 17, 17 are attached respectively. That is, a total of four spark plugs 16 and 17 are attached to each cylinder 9 at a leading side position and a trailing side position, one pair each in the width direction of the rotor 10. Note that FIG. 2 shows only one each in the width direction of the rotor 10. Each spark plug 16,1
7 is connected to the igniter coils 18, 18, ... For each of the spark plugs 16, 17, and each igniter coil 18 has a different predetermined number for each of the spark plugs 16, 17 based on the control signal from the control unit 6. It is designed to ignite at timing.

An air cleaner (not shown) and an air pump (not shown) are provided in the intake passage 2 at positions upstream of the air throttle valve 1.
9 is provided at an intermediate position, and an air pressure sensor 20 is provided at a position downstream of the air throttle valve 19. The air throttle valve 19 is opened and closed by driving an actuator 21, and the actuator 21 is driven by a control signal from the control unit 6. That is, the air throttle valve 19 is controlled by the control unit 6 to supply a predetermined flow rate of air to each cylinder 9. Further, the air throttle valve 19 is provided with a position sensor 22 which detects the valve opening degree and inputs it to the control unit. Further, the air pressure sensor 20 detects the pressure of the air supplied to each cylinder 9 through the intake port 13 and inputs it to the control unit 6.

An O2 sensor 23 is provided at a position downstream of the exhaust passage 3, and the O2 sensor 23 measures the oxygen concentration in the exhaust gas to determine the actual air-fuel ratio (actual air-fuel ratio) A / FR. It is adapted to detect and input to the control unit 6.

The MH tank 4 stores hydrogen therein,
It is equipped with a hydrogen storage alloy that can be released. This hydrogen storage alloy stores hydrogen by the hydrogen invading between the metal crystal lattices forming a metal hydride, and the formation of the metal hydride progresses by cooling to store hydrogen, and conversely, by heating. The hydrogen is released. Further, the MH tank 4 is provided with a hydrogen filling passage 24 for supplying hydrogen to the hydrogen storage alloy, and cooling water is supplied.
By circulating engine cooling water between the cooling water passage 25 that cools the hydrogen storage alloy by discharging it and the water jacket of the rotor housing 7, the hydrogen storage alloy is heated to control the discharge amount of hydrogen gas. The heating water passages 26 are connected to each other.

In the hydrogen supply passage 5, between the upstream side of the MH tank 4 and the downstream end hydrogen supply port 14, the hydrogen electromagnetic passage is opened and closed in order from the upstream side. Valve 27, pressure adjuster 28, first hydrogen pressure sensor 29, first hydrogen flow rate adjusting valve 30, second
Hydrogen pressure sensor 31, a pair of second hydrogen flow rate adjusting valves 32, 32 provided for each cylinder 9, and poppet valves 33, 3 as a pair of hydrogen injection valves provided for each cylinder 9.
3 and 3 are interposed.

The hydrogen solenoid valve 27 is opened / closed by a control signal from the control unit 6, is opened by an ON operation signal, and is closed by an OFF operation signal.

The pressure regulator 28 regulates the hydrogen gas supplied from the MH tank 4 to approximately 5 kg / cm ² , and the hydrogen pressure sensor 29 includes the pressure regulator 28 and the first hydrogen flow rate. The control unit 6 detects the hydrogen pressure in the hydrogen supply passage 5 between the control unit 6 and the adjusting valve 30.
Is input as the first hydrogen pressure.

The first hydrogen flow rate adjusting valve 30 is connected to an accelerator 34 via a wire, and the flow rate of hydrogen gas is increased or decreased substantially in proportion to the operation amount of the accelerator 34, that is, the magnitude of the accelerator opening. It is like this. This first
In the hydrogen flow rate adjusting valve 30, as shown by the solid line in FIG. 3, when the driver returns the accelerator 34 and the accelerator opening degree becomes close to 0, the first hydrogen flow rate adjusting valve 30 closes to a predetermined minimum opening degree. It is like this. The first hydrogen flow rate adjusting valve 30 has a valve opening degree, that is, an accelerator opening degree A.
An accelerator sensor 35 that detects CP and inputs it to the control unit 6 is provided. Then, the second hydrogen pressure sensor 31 detects the hydrogen pressure in the hydrogen supply passage 5 between the first hydrogen flow rate adjusting valve 30 and each of the second hydrogen flow rate adjusting valves 32, and the control unit 6 receives the second pressure. It is designed to be input as hydrogen pressure.

The second hydrogen flow rate adjusting valve 32 is adapted to be opened and closed by driving an actuator 36 to adjust the flow rate of hydrogen gas, and the actuator 36 is driven by a control signal from the control unit 6. It is supposed to be done. That is, the second hydrogen flow rate adjusting valve 32 is controlled by the control unit 6 to supply a predetermined flow rate of hydrogen gas to each cylinder 9.

Each of the poppet valves 33 is connected to the eccentric shaft 12 via a timing belt and is opened / closed at a predetermined timing in mechanical synchronization with the rotation of the eccentric shaft 12. That is, each poppet valve 33 is configured to be opened and closed with a phase difference of 180 degrees, which is equal to the phase difference between the two rotors 10, 10, between both cylinders 9, 9 and closes the closing timing of each intake port 13. The hydrogen supply port 14 opened after being delayed and opened after the intake port 13
Therefore, the hydrogen gas is injected into the cylinders 9 at the beginning of the compression stroke.

That is, in the hydrogen supply passage 5, O
As a premise, the hydrogen gas supplied from the MH tank 4 through the N-state hydrogen solenoid valve 27 is regulated to a predetermined pressure by the pressure regulator 28, and the driver's accelerator 34 is operated by the first hydrogen flow rate regulating valve 30. A mechanical fail-safe based on is achieved. Then, the hydrogen gas is
A predetermined supply amount controlled via each of the second hydrogen flow rate adjusting valves 32 is injected into each cylinder 9 at a predetermined injection timing set by each of the poppet valves 33.

In FIG. 2, 37 is a metaling oil pump (MOP) for supplying oil into each cylinder 9 to lubricate the seals. This metaling oil pump 3
6 is driven by a control signal from the control unit 6 and discharges a predetermined amount of oil according to the condition of the engine 1.

Further, as shown in FIG. 4, at the end of the eccentric shaft 12 of the engine 1 on the connection side with the automatic transmission 38, an active torque control device (hereinafter, referred to as a non-commutator motor) is provided.
39 which is simply referred to as ATCS. This AT
The CS39 is the same as the one disclosed in detail in Japanese Patent Application Laid-Open No. 64-182536 by the present applicant, and applies the positive torque to the eccentric shaft 12 by causing the non-commutator motor to function as a motor. Also,
The non-commutator electric motor is configured to function as a generator to apply a reverse torque to the eccentric shaft 12. Then, the above ATCS39
Is designed to apply a reverse torque to the eccentric shaft 12 when the torque increases and a positive torque to the eccentric shaft 12 when the torque decreases, in synchronization with the periodic fluctuation of the torque generated in the eccentric shaft 12. That is, the ATCS3
The reference numeral 9 has both the function of a starter for starting and the function of an alternator for charging. For example, when the torque is insufficient at low speed, torque assist is actively performed to control the active torque. Is.

The ATCS 39 has a starter signal detecting sensor 40 for detecting ON / OFF of the starter switch,
A rotation angle sensor 41 for detecting the rotation angle of the eccentric shaft 12 and a cylinder identification sensor 42 for identifying each cylinder 9 are provided, and these sensors 40, 41, 42 are provided.
Inputs each detected value into the control unit 6.

Next, the control in the control unit 6 will be described with reference to FIGS. This control is
The main routine shown in FIG. 5, the engine rotation synchronization interrupt process shown in FIG. 6, and the timer synchronization interrupt shown in FIG. 7 are simultaneously activated by turning on the ignition switch.

As shown in FIG. 5, the main routine first executes an initialization routine SUB1 and then determines in step S1 whether or not the timer flag WAIT is 1, and repeats step S1 until it becomes 1. When it becomes 1, the input signal processing routine SUB2 is performed. After performing the zone determination routine SUB3, the start zone control routine SUB4, the steady zone control routine SUB5, the transient zone control routine SUB6, the stalled zone control routine SUB7, and the stop zone control routine SUB8 are executed based on the determined zone. To do. afterwards,
Ignition timing control routine SUB9 is executed, and step S2
Then, the timer flag WAIT is cleared, that is, the timer flag WAIT is set to 0 and the process returns to step S1 to repeat the processing from step S1.

The engine rotation synchronizing interrupt process is shown in FIG.
As shown in, the main routine is interrupted in synchronization with the engine rotation angle (every TDC) to ignite the spark plugs 16 and 17 at a predetermined timing. That is, first, in step S3, the rotation angle sensor 4
The engine rotation pulse cycle is calculated based on the detected rotation angle value from 0, and the engine speed NE is obtained by calculating the reciprocal of the cycle in step S4. Next, in step S5, an ignition signal is output to each of the four igniter coils 18, 18, ... Based on the ignition timing of each of the ignition plugs 16, 17 determined by the ignition timing control routine SUB9, and each ignition plug 16 is output. , 17 and then returns.

As shown in FIG. 7, the timer-synchronized interrupt processing is performed once every 10 msec with respect to the main routine.
As a unit, interrupt processing is performed every 10 msec. That is, every time 10 msec elapses, the timer flag WAIT is set to 1 in step S6, and the hydrogen valve delay times H2 ODLY and H2 OD are set in step S7.
One unit, that is, 10 msec is subtracted from LY1. When the time values H2ODLY and H2ODLY1 are negative values, 0 is set. By this timer synchronous interrupt processing, step S of the main routine is performed.
The timer flag WAIT in 1 (see FIG. 5) is 10 m
It becomes 1 every sec, and the processing by the subroutines SUB2 to 9 is performed every 10 msec. In addition,
The processing by the above subroutines SUB2 to 9 is roughly 6 to 7.
It is done in msec.

Next, each content of the subroutines SUB1 to SUB9 in the above main routine will be described.

The processing of the initialization routine SUB1 is composed of steps S8 to S10 as shown in FIG. First, in step S8, the operation mode of the CPU is set, and then in step S9, the internal memory of the CPU, that is, each register and RAM are cleared. Then, in step S10, the mode of each peripheral device of the CPU such as the timer and the A / D converter is set, and its internal memory is initialized, and then the process proceeds to step S1 of the main routine.

In the processing of the input signal processing routine SUB2, as shown in FIG. 9, the detected value which is the input signal from each sensor is A / D converted and stored in step S11. That is, the detected value from the accelerator sensor 35 is the accelerator opening ACP, the detected value from the first hydrogen pressure sensor 29 is the first hydrogen pressure PH2A, and the detected value from the second hydrogen pressure sensor 31 is the second hydrogen pressure. As the PH2 B, the detected value from the O2 sensor 23 is input as the actual air-fuel ratio A / FR, and also the air throttle valve opening from the position sensor 22 and the air pressure from the air pressure sensor 20 are input. Then, the process proceeds to the next zone determination routine SUB3.

As shown in FIG. 10, in the processing of the zone determination routine SUB3, the engine speed NE and the accelerator opening degree are determined depending on whether the operating state is the start zone, the steady zone, the transient zone, the stalled zone or the stopped zone. It is determined based on ACP or the like. The above zones are classified based on the following conditions. That is, the start zone is a region in which the starter switch is ON and the engine speed NE is 500 rpm or less. The steady zone is a region where the starter switch is OFF, the engine speed is 500 rpm or more, and the accelerator opening change amount ΔACP is not more than a predetermined value. The transient zone is an area in which the amount of change in the accelerator opening in the steady zone is equal to or more than the predetermined value. The engine stall zone is an area where the engine speed is 500 rpm or less in the steady zone or the transient zone and the engine is about to stop.

The determination of each zone is first made in step S.
At 12 it is determined whether the starter switch is ON or not based on the detection signal from the starter signal detection sensor 40, and O
If it is N, the process proceeds to step S13, and if it is OFF, the process proceeds to step S14 to determine the engine speed NE. In step S13, the engine speed NE is 500r
If it is equal to or less than pm, the process proceeds to step S15, the start zone flag STA is set in the zone flag FZONE, and the process proceeds to the next start zone control routine SUB4. On the contrary, when the engine speed NE is higher than 500 rpm, the process proceeds to step S16.

In step S14, the engine speed N
When E is 500 rpm or more, the process proceeds to step S16 and the transient determination process is performed. This transient determination process is performed from the current accelerator opening ACP to the previous accelerator opening ACPOLD.
Is calculated to obtain the accelerator change amount ΔACP, and this time the accelerator opening ACP is put into the ACPOLD and updated. Then, in step S17, the accelerator change amount ΔACP is determined, and the accelerator change amount ΔACP is determined.
If CP is equal to or less than the predetermined value, the routine proceeds to step S18, where the zone flag FZONE is set to the steady zone flag ZSTC, and the routine goes to the steady zone control SUB5.

If the accelerator change amount ΔACP is not less than the predetermined value in step S17, step S1
If the accelerator change amount ΔACP is larger than the predetermined value, the process proceeds to step S20, the transition zone flag ZTRN is set in the zone flag FZONE, and the process proceeds to the transition zone control SUB6. When the accelerator change amount ΔACP is not larger than the predetermined value in step S19, the process returns to step S12 and the determination is repeated.

On the other hand, if the engine speed NE is less than 500 rpm in step S14, step S21
To the zone flag FZONE indicating the current operating state.
Is a steady zone flag ZSTC or a transient zone flag ZTRN. If the current operating state is the steady state or the transient operating state, the stalled zone flag EN is added to the zone flag FZONE in step S22.
Set ST and proceed to stalled zone control SUB7.

If the current operating state is not a steady or transient operating state in step S21, step S21
23, the engine speed NE is 0, that is, it is determined whether or not the engine is stopped, and if it is stopped, the stop zone flag STOP is set in the zone flag FZONE and the stop zone control SUB8 is set in step S24. move on. If the engine speed NE is not 0 in step S23, the process returns to step S12 to repeat the determination.

The zone operation routine SUB3 constitutes the engine operating state detecting means 45.
The transient operating state detecting means 45a is constituted by steps S12 to S14, S16, S17, S19 and S20.

In the processing by the starting zone control routine SUB4, as shown in FIG. 11, the zone flag FZONE is first confirmed in step S25, and the zone flag F is confirmed.
When ZONE is the start zone flag STA, the processes of steps S26 to S31 are performed, and the start zone flag S
If the value is other than TA, the above-described steps S26 to S31 are skipped and the process proceeds to the next steady zone control routine SUB5.

If it is in the starting zone, first, in step S26, the hydrogen electromagnetic valve 27 is turned on to turn on the MH tank 4.
Hydrogen gas is supplied to the hydrogen supply passage 5. Next, the hydrogen valve delay time H2 ODLY is set to 200 msec, and it is determined in step S28 whether the time H2 ODLY has elapsed. If 200 msec has not elapsed, the processing of the next stationary zone control routine SUB5 and subsequent steps is repeated, and step 10 in step S7 of the timer synchronous interrupt processing (see FIG. 7) is performed.
Wait for the above time H2 ODLY to become 0 by subtraction every msec. The time setting in step S27 is performed only once, and is omitted in the subsequent processing.

When 200 msec has elapsed, a value obtained by adding a predetermined increasing constant QH2 STA every 10 msec is set as the hydrogen supply amount QH2 in step S29, and this hydrogen supply amount QH2 is set to a predetermined upper limit value in step S30. Add a limit not to exceed (for example, 20%). Then, in step S31, a control signal corresponding to the hydrogen supply amount QH2 is output to each actuator 36,
The opening degree of each second hydrogen flow rate adjusting valve 33 is adjusted. That is, in the start zone control, as shown in FIG. 12, after the hydrogen solenoid valve 27 is turned on, the hydrogen valve delay time H2
Only after the passage of ODLY, the second hydrogen flow rate adjusting valves 32 are opened and hydrogen gas is supplied to the cylinders 9. Then, the amount is increased with the lapse of time, but if the amount is increased to the predetermined upper limit value, the hydrogen is supplied at the upper limit value thereafter.

In the processing by the steady zone control routine SUB5, as shown in FIG. 13, the zone flag FZONE is first checked in step S32, and if the zone flag FZONE is the steady zone flag STC, the processing in steps S34 to S42. If the flag is other than the normal zone flag STC, the above steps S34 to S42 are skipped, and after each step S33, the process proceeds to the next transient zone control routine SUB6.

In the case of the steady zone, first, at step S34, the hydrogen electromagnetic valve 27 is turned on to turn on the MH tank 4.
Hydrogen gas is supplied to the hydrogen supply passage 5. Next, in step S35, the target air-fuel ratio TRGA / F is set to the accelerator opening A
It is calculated from a predetermined three-dimensional map using CP and engine speed NE as parameters. This map is designed to be given as a value that does not exceed the theoretical air-fuel ratio even with the maximum air-fuel ratio.
It is controlled to be leaner than the stoichiometric air-fuel ratio in all regions in the relationship between P and the engine speed NE, that is, in all operating conditions.

Then, in step S36, the target intake air amount TQ
AIR is obtained from a predetermined map based on the relationship between the target air-fuel ratio TRGA / F and the engine speed NE, and in step S37, the actual intake air amount QAIR is related to the detected value of the air pressure sensor 20 and the engine speed NE. Calculated from the map created in advance based on Next, in step S38, the target hydrogen supply amount QH2 is obtained from a predetermined map based on the relationship between the target air-fuel ratio TRGA / F and the actual intake air amount QAIR.

Next, in steps S39 to S41, PI control is performed so that the hydrogen supply amount QH2 that achieves the target air-fuel ratio TRGA / F is obtained. That is, the above step S3
In step 9, the feedback (F / B) gain of the air-fuel ratio is obtained from the map based on the target hydrogen supply amount QH2, and in step S40 the target air-fuel ratio TRGA / F and the actual air-fuel ratio A / FR obtained by the O2 sensor are calculated. The deviation ΔA / F is calculated from the above, and the integration constant ΣI is calculated based on the positive / negative of the deviation ΔA / F.
In step S41, calculation of F / B constant CFB and this F
The target hydrogen supply amount QH2 is corrected by multiplying the / B constant CFB.

In step S42, a control signal based on the target intake air amount TQAIR is output to the actuator 21 to adjust the opening of the air throttle valve 19, and a control signal based on the target hydrogen supply amount QH2 is sent to each actuator 36. To adjust the opening degree of each second hydrogen flow rate adjusting valve 32. Finally, in step S33, the hydrogen supply amount QH2
Based on the relationship between the engine speed NE and the engine speed NE, the discharge amount of the MOP 37 is obtained from a predetermined map, and a control signal based on this discharge amount is output to the MOP 37.

In the process by the transient zone control routine SUB6, as shown in FIG. 14, the zone flag FZONE is first checked in step S43. If the zone flag FZONE is the transient zone flag TRN, the processes in steps S45 to S53 are performed. If the flag is other than the transient zone flag TRN, the above steps S45 to S53 are skipped, and after each step S44, the process proceeds to the next stalling zone control routine SUB7.

If it is in the transition zone, first, in step S45, the hydrogen electromagnetic valve 27 is turned on to open it. Next, at step S46, the target air-fuel ratio TRGA / F
At step S of the steady zone control routine SUB6.
The calculation is performed from the same three-dimensional map as 35. Therefore, the obtained target air-fuel ratio TRGA / F is controlled leaner than the stoichiometric air-fuel ratio.

Then, in step S47, the lean side correction is further added to the target air-fuel ratio TRGA / F in step S46 according to the accelerator change amount ΔACP.
That is, the correction value CA is calculated based on the accelerator change amount ΔACP.
F is obtained from a predetermined map, and the target air-fuel ratio TRGA / F after correction is calculated by multiplying this correction value CAF by the target air-fuel ratio TRGA / F in step S46.
It should be noted that the above map is set so that the larger the accelerator change amount ΔACP, the more leaner the correction becomes.

Next, at step S48, the target hydrogen supply amount Q
H2 is the target air-fuel ratio TRGA / F and engine speed N
The target intake air amount QTAIR is obtained from a predetermined map based on the relationship with E, and the target intake air amount QTAIR is obtained from a predetermined map based on the relationship between the target hydrogen supply amount QH2 and the engine speed NE in step S49.

Next, in steps S50 to S52, the steady zone control routine SUB5 (FIG. 13) is set so that the hydrogen supply amount QH2 that realizes the target air-fuel ratio TRGA / F is obtained.
The PI control is performed in the same manner as in steps S39 to S41 of the reference) to obtain the corrected target hydrogen supply amount QH2.

Then, in step S53, the above step S
A control signal based on the target intake air amount TQAIR of 49 is output to the actuator 21 to adjust the opening of the air throttle valve 19, and a control signal based on the corrected target hydrogen supply amount QH2 is output to each actuator 36. The opening degree of each second hydrogen flow rate adjusting valve 32 is adjusted. Finally, in step S44, the discharge amount of the MOP 37 is obtained from a predetermined map based on the relationship between the hydrogen supply amount QH2 and the engine speed NE, and the control signal based on this discharge amount is used as the above MOP3.
Output to 7.

The target air-fuel ratio setting means 43 in this embodiment is constituted by step S46 in the transient zone control routine SUB6 and step S35 in the steady zone control routine SUB5. Further, step S47 in the transition zone control routine SUB6 constitutes a correction means 43a for further correcting the target air-fuel ratio TRGA / F set by the target air-fuel ratio setting means 43 to the lean side. further,
Steps S48 to S53 in the transient zone control routine SUB6 and the steady zone control routine SU
By steps S36 to S42 in B5, the supply control means 44 for controlling the supply of the supply amount of air and hydrogen gas based on the target air-fuel ratio is configured.

The stalled zone control routine SUB7
As shown in FIG. 15, the processing by step S54 is performed first.
If the zone flag FZONE is the stalled zone flag EST, the processes of steps S55 to S60 are performed. If the zone flag FZONE is other than the stalled zone flag ENT, the above step S5 is performed.
Steps 54 to S60 are skipped and the next stop zone control routine S is executed.
Proceed to UB8.

In the stalled zone, first, in step S54, the hydrogen electromagnetic valve 27 is turned off to shut off the hydrogen gas from the MH tank 4. Next, the hydrogen valve delay time H2 ODLY1 is set to 80 msec, and step S
At 57, it is determined whether the time H2 ODLY1 has elapsed. 80
If msec has not elapsed, the following processes of the stop zone control routine SUB8 and subsequent steps are repeated, and the time H2 ODLY1 becomes 0 by the subtraction every 10 msec in step S7 of the timer synchronous interrupt process (see FIG. 7). The time setting in step S56 is performed only once, and is omitted in the subsequent processing.

When 80 msec has elapsed, a value obtained by adding a predetermined increase constant QH2 EST1 is set as the hydrogen supply amount QH2 every 10 msec in step S58, and this hydrogen supply amount QH2 is set to a predetermined upper limit value in step S59. Add a limit not to exceed (for example, 20%). Then, in step S60, a control signal corresponding to this hydrogen supply amount QH2 is output to each actuator 36,
The opening degree of each second hydrogen flow rate adjusting valve 33 is adjusted. That is, in the engine zone control, after the hydrogen solenoid valve 27 is closed, the hydrogen valve delay time H2 ODLY1
After the passage of, each second hydrogen flow rate adjusting valve 32 is opened and hydrogen gas is supplied to each cylinder 9. As a result, the hydrogen gas remaining in each cylinder 9 is completely burned. In addition, delaying the hydrogen valve delay time H2 ODLY1 by not increasing the delay but increasing all at once
This is because the closing operation of the air throttle valve 19 causes the rich side to become too rich.

In the processing by the stop zone control routine SUB8, as shown in FIG. 16, the zone flag FZONE is first checked in step S61. If the zone flag FZONE is the stop zone flag STOP, the processing in steps S62 to S65 is performed. If the flag is other than the stop zone flag STOP, the above steps S62 to S6 are performed.
By skipping step 5, the routine proceeds to the next ignition timing control routine SUB9.

In the case of the stop zone, first, in step S62, the hydrogen electromagnetic valve 27 is turned off to shut off the hydrogen gas from the MH tank 4. Next, in step S63, 0% is set in the hydrogen supply amount QH2, and 0% is set in the target intake air amount QAIR in step S64, and a control signal is output to the corresponding actuators 21 and 36 in step S65 to output the air throttle valve 19 And each second hydrogen flow rate adjusting valve 32 is closed.

The process of the ignition timing control routine SUB9 is, as shown in FIG. 17, the hydrogen supply amount Q set in the zone control routines SUB4 to SUB8 in step S66.
The ignition timing of each of the spark plugs 16 and 17 is obtained from a map using H2 and engine speed NE as parameters. Then, the process proceeds to step S2 in the main routine (see FIG. 5).

In the case of the engine 1, the target air-fuel ratio setting means 43 causes the accelerator opening ACP and the engine speed N in the steady operation state, that is, in the steady zone.
A target air-fuel ratio that is leaner than the stoichiometric air-fuel ratio is set in all regions of E, and the supply control means 44 supplies air and hydrogen gas in an amount based on the target air-fuel ratio to each cylinder 9. Therefore, the supplied hydrogen gas can be completely burned in each cylinder 9.
Therefore, it is possible to reliably prevent the unburned hydrogen from flowing into the exhaust passage 3, and it is possible to reliably prevent the occurrence of afterburn and the increase of emissions. Further, at this time, even if the air-fuel mixture is leaner than the stoichiometric air-fuel ratio, the combustible limit of hydrogen gas is sufficiently high and the combustibility can be sufficiently maintained, and deterioration of the combustibility is suppressed. be able to.

Moreover, particularly in a transient operating state where the deviation of the air-fuel ratio is apt to occur, that is, in the transient zone, the target air-fuel ratio is controlled by the target air-fuel ratio setting means 43 to be leaner than the theoretical air-fuel ratio. However, even if the actual air-fuel ratio in each cylinder 9 deviates to the rich side from the target air-fuel ratio due to sudden acceleration or deceleration, the actual air-fuel ratio is corrected to the lean side. It is possible to reliably maintain the fuel ratio on the lean side of the stoichiometric air-fuel ratio. Therefore, even in the transient operation state, each cylinder 9
Can burn all the hydrogen gas supplied to
It is possible to more surely prevent the occurrence of afterburn and the increase of emission due to the outflow of unburned hydrogen.

The present invention is not limited to the above embodiment, but includes various other modifications. That is, in the above embodiment, the hydrogen engine is shown as a rotary piston engine, but the present invention is not limited to this, and it may be provided as a reciprocating engine, for example. Even in this case, the same action and effect can be obtained.

Further, in the above embodiment, the supply control means 44
Is configured to control each supply amount of hydrogen and air, but is not limited to this, and may be configured to control, for example, one of the supply amounts.

[0071]

As described above, according to the air-fuel ratio control system for a hydrogen engine in the invention of claim 1, the air-fuel ratio is controlled to be leaner than the stoichiometric air-fuel ratio in all operating regions. All hydrogen gas supplied to the engine can be burned. Therefore, it is possible to reliably prevent the unburned hydrogen from flowing out to the exhaust pipe, and it is possible to reliably prevent the occurrence of afterburn and the increase of emission. Further, at this time, even if the air-fuel mixture is leaner than the stoichiometric air-fuel ratio, the combustible limit of hydrogen gas is sufficiently high and the combustibility can be sufficiently maintained, and the deterioration of the combustibility can be suppressed. Can be planned.

According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the target air-fuel ratio is further corrected to the lean side in the transient operation state where the deviation of the air-fuel ratio is likely to occur. Even if the actual air-fuel ratio deviates to the rich side due to sudden acceleration or deceleration, etc., the actual air-fuel ratio is surely set to the lean side of the stoichiometric air-fuel ratio. Can be maintained. Therefore, even in the transient operation state, it is possible to burn all the hydrogen gas supplied to the engine, and it is possible to more reliably prevent the occurrence of afterburn and the increase of emission due to the outflow of unburned hydrogen.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 2 is an overall configuration diagram of a hydrogen engine.

FIG. 3 is a diagram showing opening characteristics of first and second hydrogen flow rate adjusting valves.

FIG. 4 is a side view showing a part of the engine of FIG.

FIG. 5 is a flowchart of a main routine.

FIG. 6 is a flowchart of engine rotation synchronization interrupt processing.

FIG. 7 is a flowchart of timer synchronous interrupt processing.

FIG. 8 is a flowchart of an initialization routine.

FIG. 9 is a flowchart of an input signal processing routine.

FIG. 10 is a flowchart of a zone determination routine.

FIG. 11 is a flowchart of a start zone control routine.

FIG. 12 is a diagram showing hydrogen supply characteristics in a starting zone.

FIG. 13 is a flowchart of a steady zone control routine.

FIG. 14 is a flowchart of a transient zone control routine.

FIG. 15 is a flowchart of an engine stall control routine.

FIG. 16 is a flowchart of a stop zone control routine.

FIG. 17 is a flowchart of an ignition timing control routine.

[Explanation of symbols]

 1 Hydrogen Engine 2 Intake Passage 5 Hydrogen Supply Passage 19 Air Throttle Valve 33 Second Hydrogen Flow Rate Control Valve 43 Target Air-Fuel Ratio Setting Means 43a Correction Means 44 Supply Control Means 45 Operating State Detection Means 45a Transient Operating State Detection Means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location F02M 21/02 311 D G H

Claims (2)

[Claims] 1. An air-fuel ratio control device for a hydrogen engine using hydrogen as fuel, comprising an operating state detecting means for detecting an operating state of the engine, and a target air-fuel ratio based on an output signal from the operating state detecting means. As target air-fuel ratio setting means for setting an air-fuel ratio leaner than the stoichiometric air-fuel ratio in all operating states, and supply for controlling at least one supply amount of hydrogen and air based on the set target air-fuel ratio An air-fuel ratio control device for a hydrogen engine, comprising: a control means. 2. A transient operating state detecting means for detecting a transient operating state of the engine, and a target air-fuel ratio setting means based on an output signal from the transient operating state detecting means when the transient operating state is detected. The air-fuel ratio control device for a hydrogen engine according to claim 1, further comprising: a correction unit that further corrects the target air-fuel ratio toward the lean side.