JP2023082746A - engine - Google Patents

Abstract

To provide a hydrogen engine for promoting practical use by improving safety property.SOLUTION: The engine has a cylinder block 1, a cylinder head 2, and a head cover 16, the cylinder head 2 being provided with an intake port 7, an exhaust port 8, an intake valve 9, an exhaust valve 10, and camshafts 14, 15. When the engine is of a direct injection type, a nozzle 22 of a fuel injection valve 20 is exposed into a recess 6 and an ignition plug 25 is arranged at the lateral part of the cylinder head 2. The head cover 16 is formed with an encircling frame part 16a encircling the upper part of the fuel injection valve 20, while the encircling frame part 16a is blocked by an upper cover 16b and a hydrogen detection sensor 26 is arranged on the upper cover 16b. The leakage of hydrogen fuel from the fuel injection valve 20, when happening, can be detected at a real time. The leaked hydrogen fuel is not diffused to the outside, and therefore high safety is actualized.SELECTED DRAWING: Figure 1

Description

The present invention relates to an engine (internal combustion engine) fueled by hydrogen.

Hydrogen has long attracted attention as a clean fuel to replace petroleum, and the use of hydrogen as fuel for engines has been studied, but has not yet been put to practical use. One of the reasons why it has not been put to practical use is that hydrogen is only 1/15th the mass of air and is highly volatile and flammable. That is, the problem of safety lies as a problem that hinders the practical use of hydrogen engines.

The safety of hydrogen engines can be examined from several viewpoints, but the most important is the problem of hydrogen leakage. Regarding this point, in Patent Document 1, as a measure against leakage of hydrogen from the fuel tank, hydrogen is lighter than air and has the property of rising upward, so hydrogen detection sensors are arranged above the passenger compartment and trunk room. , discloses a system that issues an alarm when a hydrogen detection sensor detects hydrogen.

JP-A-2-290758

Patent Document 1 focuses on the fact that the passenger compartment and the trunk room are closed spaces on the premise that the fuel tank is arranged in the lower part of the vehicle body and the trunk room, and the passenger compartment and the trunk existing as elements of the vehicle. It can be said that the hydrogen detection sensor is placed in the trunk room.

However, since both the passenger compartment and the trunk room have large volumes, it takes time for the hydrogen gas to reach the upper end of these spaces, and there is a risk that leaked hydrogen cannot be detected in a timely manner. That is, there is a problem that it is highly possible that detection is not possible until after a considerable amount of hydrogen has leaked, and a problem that the diffusion of leaked hydrogen gas cannot be prevented.

Hydrogen can also leak around the engine, but since the engine has parts that get hot and there are many electric parts and harnesses, the danger of hydrogen leakage is high. Therefore, there is a high need for detection technology when hydrogen leaks around the engine.

Therefore, as a means for detecting hydrogen leakage around the engine, applying the idea of Patent Document 1, for example, it is conceivable to arrange a hydrogen detection sensor on the underside of the hood (bonnet) of the vehicle. There is a high possibility that the gas is blown away by the running wind and cannot be detected, and there is a problem that it is not possible to prevent the leaked hydrogen gas from contacting the high temperature parts of the engine. .

The invention of the present application was made against the background of such a situation, and is intended to disclose a technology that can quickly detect hydrogen leaks around the engine while preventing the diffusion of the hydrogen in the engine using hydrogen as fuel. It is something to do.

The engine of the present invention is
``It is equipped with a fuel injection valve that injects hydrogen fuel into a combustion chamber or an intake port, a cover that covers the fuel injection valve, and a hydrogen detection sensor that is arranged inside the cover.''
It is configured.

In this case, a dedicated cover can be used, or a part or all of an engine component such as a head cover can also be used. In any case, it is preferable to interpose a sealing material (sealing agent) between the contact surface between the cover and the cylinder head or the like.

In addition, as a countermeasure after detecting a hydrogen leak with the hydrogen detection sensor, as an emergency situation, for example, a lamp flashes on the driver's seat panel, and voice or text guidance is given to immediately stop operation or move to a service shop. can. The characters may be displayed on a monitor provided on the panel of the driver's seat, or may be displayed in the form of interruption using the screen of the car navigation system.

In a hydrogen engine, since hydrogen is injected into a combustion chamber or an intake port by a fuel injection valve, leakage from the vicinity of the fuel injection valve due to aging and the like is the greatest concern. However, in the present invention, since the fuel injection valve is covered with a cover, even if hydrogen leaks around the fuel injection valve, it will not diffuse widely. Therefore, it is possible to prevent an accident in which the leaked fuel contacts a high-temperature part of the engine and ignite, and since the space enclosed by the cover is small, hydrogen leakage can be detected in real time.

As described above, in the present invention, when hydrogen leaks, it can be detected quickly in a state in which diffusion is prevented, so safety can be greatly improved and it can greatly contribute to the practical use of hydrogen engines.

It is also possible to suck the hydrogen gas accumulated in the space covered by the cover with a vacuum pump and return it to the intake system. There is

1 is a longitudinal sectional view of a first embodiment; FIG. It is a longitudinal cross-sectional view of 2nd Embodiment. It is a longitudinal cross-sectional view of 3rd Embodiment.

Next, embodiments of the present invention will be described based on the drawings. In the following description, terms such as front-rear and left-right are used to specify directions. The front-rear direction is the direction of the crank axis, and the left-right direction is the direction orthogonal to the crank axis and the cylinder axis.

(1). Structure of the First Embodiment First, the first embodiment shown in FIG. 1 will be described. The engine is of a multi-cylinder type for vehicles, and has a cylinder block 1 and a cylinder head 2 fixed to the upper surface thereof as an engine body. A plurality of cylinder bores 3 are formed in the cylinder block 1 side by side in the front-rear direction, and a piston 4 is slidably fitted in each cylinder bore 3 . The piston 4 is connected via a connecting rod 5 to a crankshaft (not shown). A gasket is interposed between the cylinder head 2 and the cylinder block 1, but its illustration is omitted.

A mountain-shaped (pent roof-shaped) recess 6 that opens toward each cylinder bore 3 is formed in the lower surface of the cylinder head 2 . A pair of intake ports 7 and exhaust ports 8 are opened. In the cylinder head 2, a pair of front and rear intake valves 9 for opening and closing the outlet of the intake port 7 and a pair of front and rear exhaust valves 10 for opening and closing the inlet of the exhaust port 8 slide through valve guides (bushes) 11, respectively. mounted movably.

The intake valve 9 and the exhaust valve 10 are biased in the closing direction by a spring 12, and their upper ends are in contact with cam lobes of camshafts 14 and 15 via valve caps 13, respectively. Therefore, although the valves 9 and 10 of this embodiment are of the direct push type, it is also possible to employ a method of driving them via rocker arms. The intake valve 9 and the exhaust valve 10 are inclined with respect to the cylinder axis so that the distance between them increases as they go upward when viewed from the crank axis direction, but a type parallel to the cylinder axis can also be adopted.

Although not shown, the camshaft is rotatably held by a cam cap, and the valve train is covered by a head cover 16. As shown in FIG. The outer peripheral portion of the head cover 16 is fixed to the outer peripheral surface of the cylinder head 2 with bolts. Moreover, the head cover 16 has a sealing material interposed on the mating surface with the cylinder head 2 .

Each intake port 7 opens to the intake side surface 2 a of the cylinder head 2 , and each intake port 7 communicates with a branch pipe of an intake manifold 17 fixed to the intake side surface 2 a of the cylinder head 2 . It is also possible to employ a type in which a pair of front and rear intake ports 7 are branched from one collective port, and one branch pipe of the intake manifold 17 is communicated with the collective port.

The exhaust port 8 opens to the exhaust side of the cylinder head 2, and an exhaust manifold 18 having branch pipes communicating with each exhaust port 8 is fixed to the exhaust side of the cylinder head 2. It is also possible to adopt a system in which an exhaust collecting portion is formed inside and one exhaust pipe or exhaust turbocharger is connected to one exhaust outlet hole. In the hydrogen engine, since the exhaust gas is water vapor, a catalyst for purifying the exhaust gas is not required.

A center hole 19 that opens vertically is formed in the upper part of the approximately central part of each recess 6 in the cylinder head 2. Hydrogen fuel (liquid hydrogen) is atomized in this center hole 19 and is injected into the combustion chamber. A fuel injection valve (injector) 20 for ejecting fuel is arranged. Therefore, the engine of this embodiment is of the direct injection type. Although the fuel injection valve 20 is arranged concentrically with the cylinder axis, it may be arranged with a misalignment in the left-right direction or the front-rear direction, or may be inclined with respect to the cylinder axis.

Above the fuel injection valve 20 is a control unit 21 containing an electromagnetic solenoid or the like. Liquid hydrogen is sprayed from a nozzle 22 at the lower end into the combustion chamber in an atomized (gasified) state. Hydrogen fuel is supplied from a delivery pipe 31 located near the control unit 21 .

A cable 23 is connected to the control unit 21 , and the cable 23 is drawn out through a connector 24 provided on an upper cover 16 b fixed to the head cover 16 . The connector 24 is attached to the top cover 16b in a completely sealed state.

A spark plug 25 is attached to a portion of the cylinder head 2 below the intake port 7 with the electrode exposed in the recess 6 . Accordingly, the spark plug 25 is arranged in an inclined posture with its axial center lying flat.

1 (and FIG. 2) both the fuel injection valve 20 and the intake/exhaust ports 7, 8 are indicated by solid lines. , the fuel injection valve 20 and the intake/exhaust ports 7 and 8 do not appear together when cut along one plane. Therefore, in FIG. 1, the portion where the fuel injection valve 20 is provided and the portion where the intake/exhaust ports 7 and 8 are provided are cut along a plane that is displaced in the front-rear direction.

In FIG. 1, the spark plug 25 is shown positioned below one intake port 7, but the spark plug 25 is actually positioned below a portion between the front and rear intake ports 7. ing. Therefore, in practice, the spark plug 25 is arranged at a higher position than in the state shown in FIG. Although not labeled, the cylinder head 2 is provided with a cooling water jacket.

It is also possible to arrange the fuel injection valve 20 and the spark plug 25 so that they are vertically long and arranged in the front-rear direction so that the lower ends of both are exposed in the recess 6 . In this case, it is possible to slightly incline the fuel injection valve 20 and the spark plug 25 with respect to the cylinder axis.

A portion of the head cover 16 corresponding to each fuel injection valve 20 is integrally formed with a downward surrounding frame portion 16a that surrounds the portion of the fuel injection valve 20 exposed above the cylinder head 2 (mainly the control unit 21) from the outer peripheral direction. , and the surrounding frame portion 16a is covered from above with the above-described upper cover 16b.

A lower end portion 16c of the surrounding frame portion 16a of the head cover 16 is tightly fitted to a cylindrical boss formed on the cylinder head 2 via a sealing means, and is formed around the entire circumference of the lower edge of the upper cover 16b. The flange 16d is fixed to the upper surface of the head cover 16 with screws via sealing means. ing. A hydrogen detection sensor 26 is arranged on the ceiling surface of the upper cover 16b.

Accordingly, in this embodiment, the cover described in the claims is constituted by the surrounding frame portion 16a formed on the head cover 16 and the upper cover 16b which is separate from the head cover 16, and a part of the head cover 16 is used as a sensor. It is also used as a surrounding cover. Needless to say, a cable 27 is connected to the hydrogen detection sensor 26, and the cable 27 is connected to an ECU (engine control unit). Although the delivery pipe 31 described above is elongated in the front-rear direction and penetrates each of the surrounding frame portions 16a, the fuel supply pipe may be individually connected to each fuel injection valve 20 without using the delivery pipe 31. .

In the illustrated example, each of the enclosing frame portions 16a is individually covered with the upper cover 16b. can also be covered. In this case, the hydrogen detection sensor 26 may be arranged at one location (or a plurality of locations less than the number of fuel injection valves 20) in the front and rear intermediate portions of the upper cover 16b.

(2).Summary Since the fuel injection valve 20 is constantly in use while the engine is running, the sealing performance gradually deteriorates due to wear and tear over time, and hydrogen fuel leaks out of the fuel injection valve 20. there is a possibility to do so. Alternatively, it cannot be said that there is no possibility that the hydrogen fuel leaks from the fuel injection valve 20 due to other factors such as an accident.

Since hydrogen is highly flammable, it is dangerous if it leaks, and it can be said that the possibility of leakage from the fuel injection valve 20 is the highest around the engine. Since the sensor 26 is arranged, the fact that hydrogen leaks from the fuel injection valve 20 can be detected immediately, and the driver can be notified by an alarm or the like so that necessary measures can be taken.

Specifically, the alarm lamp on the driver's seat panel flashes, the fact of leakage is announced by voice, and the fact of leakage and countermeasures are displayed on various display monitors or car navigation monitors. be able to. As a coping method, for example, stop at a safe place and contact a service provider. If the degree of leakage is minor, it is possible to have the vehicle run directly at a service factory. As a countermeasure against leakage, it is also possible to suck with a vacuum pump and return it to the intake port 7 .

In this embodiment, even if the hydrogen fuel leaks from the fuel injection valve 20, it does not diffuse to the outside, so safety is high. In addition, since hydrogen has a lower specific gravity than air and tends to rise upwards, if the upper cover 16b is formed to protrude upward from the head cover 16 as in the embodiment, the leaked hydrogen will flow into the upper cover 16b. Since there is a tendency for the dust to accumulate in the air, there is an advantage that the detection accuracy can be improved and the safety can be further improved by eliminating the chance of contact with an electrical component such as a VVT.

Now, a small amount of hydrogen fuel may blow through to the crankcase as blow-by gas. Some of the blow-by gas can be returned to the intake system via the gas-liquid separation chamber (separator chamber), but some may flow into the valve gear chamber through the timing chain arrangement space. . Therefore, hydrogen contained in the blow-by gas can also be detected by the hydrogen detection sensor 26, but it is necessary to distinguish between the presence of hydrogen accompanying normal operation and the presence of hydrogen leaked from the fuel injection valve 20.

Regarding this point, it is necessary to set in advance the numerical value of the hydrogen concentration that can be safely operated and the hydrogen concentration that is judged to be dangerous, and if the detected hydrogen concentration exceeds the dangerous concentration, take measures such as an alarm. good. Alternatively, it is also possible to set the sensitivity of the hydrogen detection sensor 26 to such a level that it can detect a dangerous amount, and set it so that hydrogen contained in the blow-by gas does not react.

(3).Other Embodiments FIGS. 2 and 3 show other embodiments. These are other examples of the arrangement position of the fuel injection valve 20 and the spark plug 25 .

Among them, in the second embodiment shown in FIG. 2, a plug hole 28 is provided in the upper part of each recess 6 in the cylinder head 2, and an ignition plug 25 is screwed into the plug hole 28. , a cylindrical ignition boss portion 16e provided on the head cover 16 is tightly fitted. On the other hand, the fuel injection valve 20 is placed above the intake port 7 in an inclined position, and the nozzle 22 faces the intake port 7 . Therefore, the second embodiment is of the port injection type.

A flange 29 provided on the body of the fuel injection valve 20 is fixed to a seat surface 30 formed on the cylinder head 2 with screws (not shown). A delivery pipe 31 extending in the front-rear direction is connected to the base end (upper end) of the fuel injection valve 20 . The control unit 21 is provided so as to protrude outward from the body.

In this embodiment, since a part of the fuel injection valve 20 partially protrudes from the intake side of the cylinder head 2, the fuel injection valve 20 is surrounded from below and from the side at the intake side of the cylinder head 2. A projecting main body portion 32 is formed, and a projecting lid portion 33 is formed on the head cover 16 to close the projecting main body portion 32 of the cylinder head 2 from above. is fixed with The hydrogen detection sensor 26 is arranged on the lower surface of the projecting lid portion 33 . Therefore, in this embodiment, the overhanging main body portion 32 and the overhanging lid portion 33 correspond to the cover described in the claims.

Needless to say, a liquid or solid sealing material is interposed between the mating surfaces of the overhanging main body portion 32 and the overhanging lid portion 33 . Since the delivery pipe 31 is provided in this embodiment, the overhanging main body portion 32 and the overhanging lid portion 33 are elongated in the front-rear direction. The hydrogen detection sensor 26 may be arranged corresponding to each fuel injection valve 20 , or may be arranged at one or a plurality of locations without corresponding to each fuel injection valve 20 .

When a fuel supply pipe is individually laid to each fuel injection valve 20 without using the delivery pipe 31, it is possible to form the overhang main body portion 32 and the overhang cover portion 33 for each location of each cylinder. It is also possible to prepare a separate cover in which portions corresponding to the overhanging main body portion 32 and the overhanging lid portion 33 are integrated, and fasten this to the cylinder head 2 with screws.

If two intake ports 7 corresponding to one cylinder are separated over the entire length, two fuel injection valves 20 are required corresponding to one cylinder. On the other hand, in the case of a type in which two intake ports 7 are separated from one collecting portion, it is sufficient to inject fuel from one fuel injection valve 20 to the collecting portion.

The third embodiment shown in FIG. 3 is of a direct injection type in which the spark plug 25 is exposed at the center of the recess 6 and the fuel injection valve 20 is exposed to the recess 6 . Therefore, the fuel injection valve 20 is inclined with respect to the cylinder axis, and the nozzle 22 is exposed in the recess 6 between the front and rear intake ports 7 .

In this embodiment, since the upper portion of each fuel injection valve 20 is exposed to the outside of the cylinder head 2, a front-to-rear longitudinal cover 34 surrounding the upper portion of the fuel injection valve 20 is formed, and this cover 34 is attached to the cylinder. It is fixed to the side surface of the head 2. The hydrogen detection sensor 26 is arranged on the upper inner surface of the cover 34 . Since fuel is supplied to the fuel injection valve 20 from the delivery pipe 31, the cover 34 is long in the front-rear direction. The top surface of the piston 4 is formed with a recess for diffusing the fuel ejected from the fuel injection valve 20 .

Although the embodiments of the present invention have been described above, the present invention can be embodied in various other ways. For example, in the illustrated embodiment, the cover is provided on the head cover or the cylinder head, but it is also possible to provide the cover integrally with the fuel injection valve itself and fix the cover to the cylinder head.

The present invention can be embodied in a hydrogen engine. Therefore, it can be used industrially.

1 Cylinder Block 2 Cylinder Head 3 Cylinder Bore 4 Piston 6 Recess Constituting Combustion Chamber 7 Intake Port 8 Exhaust Port 9 Intake Valve 10 Exhaust Valve 16 Head Cover 16a Surrounding Frame Part Constituting Cover 16b Constituting Cover Upper cover 20 Fuel injection valve 21 Control unit 22 Nozzle 25 Ignition plug 26 Hydrogen detection sensor 31 Delivery pipe 32 Protruding main body portion constituting cover 33 Protruding lid portion constituting cover 34 Cover

Claims (1)

A fuel injection valve that injects hydrogen fuel into a combustion chamber or an intake port, a cover that covers the fuel injection valve, and a hydrogen detection sensor that is arranged inside the cover.
engine.

Images