engine

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

[Technical Field]

[0001] The present invention relates to a hydrogen-fueled engine (internal combustion engine). [Background technology]

[0002] Hydrogen has long been attracting attention as a clean fuel to replace petroleum, and research has been conducted into using hydrogen as a fuel in engines, but it has not yet been put to practical use. One of the reasons for this is that hydrogen has only one-fifteenth the mass of air and is highly volatile and flammable. In other words, safety issues remain a major obstacle to the practical use of hydrogen engines.

[0003] The safety of hydrogen engines can be considered from several perspectives, but the issue of hydrogen leakage is particularly important. In this regard, Patent Document 1 discloses a system to prevent hydrogen leakage from the fuel tank, in which hydrogen detection sensors are placed above the passenger compartment or trunk, and an alarm is issued if the hydrogen detection sensor detects hydrogen, since hydrogen is lighter than air and tends to rise upwards. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2-290758 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 assumes that the fuel tank is located under the vehicle body or in the trunk, and focuses on the fact that the passenger compartment and trunk are closed spaces, and can be said to place a hydrogen detection sensor in the passenger compartment and trunk, which are elements of the vehicle.

[0006] However, because both the passenger compartment and the trunk have large volumes, it takes time for the hydrogen gas to reach the top of these spaces, which can make it difficult to detect leaked hydrogen in a timely manner. This means that there is a high possibility that hydrogen will not be detected until a considerable amount of hydrogen has leaked, and there is also the problem that the leakage of leaked hydrogen gas cannot be prevented.

[0007] Hydrogen can also leak around the engine, but the danger of hydrogen leaks is high because the engine has parts that reach high temperatures and also contains many electrical parts and harnesses. Therefore, there is a great need for technology to detect hydrogen leaks around the engine.

[0008] Therefore, as a means of detecting hydrogen leaks around the engine, it is conceivable to apply the concept of Patent Document 1 and place a hydrogen detection sensor on the underside of the vehicle's hood (bonnet), for example. However, this has problems such as the high possibility that hydrogen gas will be blown away by the wind while driving and will not be detected, and it is not possible to prevent leaked hydrogen gas from coming into contact with high-temperature parts of the engine, making it an insufficient safety measure.

[0009] The present invention was made against this background and aims to disclose a technology that can quickly detect hydrogen leaks around a hydrogen-fueled engine while preventing the hydrogen from diffusing. [Means for solving the problem]

[0010] The present invention teeth, " A reciprocating engine having a combustion chamber that pushes a piston down by the combustion of hydrogen, a cylinder head in which the combustion chamber and an intake port communicating with the combustion chamber are formed and in which a valve mechanism is arranged, a head cover fixed to the cylinder head so as to cover the valve mechanism, and a fuel injection valve that injects hydrogen fuel into the combustion chamber. In this basic configuration, "The fuel injection valve has a control unit arranged in a space surrounded by the head cover, and the control unit is covered by a fuel injection valve cover that is either formed integrally with the head cover or constructed separately from the head cover and fixed to the head cover, and a hydrogen detection sensor is arranged on the inner surface of the fuel injection valve cover." The structure is as follows.

[0011] As claimed, for fuel injection valves It is possible to use a dedicated cover, or it is also possible to use a part or all of the engine's components, such as a head cover, as the cover. but,In any case, it is preferable to interpose a sealant (sealing agent) on the contact surface between the cover and the cylinder head or the like. The present invention also includes the invention of claim 2, and this invention is the invention of claim 1, "The fuel injection valve cover is composed of a surrounding frame portion that is integrally formed to surround the control unit of the fuel injection valve and protrudes toward the cylinder head, and an upper cover that is separate from the head cover and fixed to the head cover." The structure is as follows.

[0012] As a countermeasure after detecting a hydrogen leak by the hydrogen detection sensor, for example, a lamp may be flashed on the driver's seat panel to indicate an emergency, and voice or text guidance may be provided to promptly stop driving or go to a service shop. The text may be displayed on a monitor provided on the driver's seat panel, or may be displayed as an interruption on the screen of the car navigation system. [Effects of the Invention]

[0013] In a hydrogen engine, hydrogen is injected into the combustion chamber or intake port by a fuel injection valve, so the biggest concern is leakage from the periphery of the fuel injection valve due to wear over time, etc. For fuel injection valves Because the fuel injection valve is covered with a cover, even if hydrogen leaks around the fuel injection valve, it will not spread widely. Therefore, it is possible to prevent accidents such as leaked fuel coming into contact with high-temperature parts of the engine and catching fire. For fuel injection valves Because the space enclosed by the cover is small, any hydrogen leak can be detected in real time.

[0014] In this way, the present invention can quickly detect hydrogen leakage while preventing diffusion, thereby significantly improving safety and making a significant contribution to the practical application of hydrogen engines.

[0015] For fuel injection valves It is also possible to use a vacuum pump to suck out the hydrogen gas that has accumulated in the space covered by the cover and return it to the intake system. In this case, it is possible to prevent the hydrogen gas from continuing to accumulate, which has the advantage of further improving safety. [Brief explanation of the drawings]

[0016] [Figure 1]FIG. 1 is a longitudinal sectional view of a first embodiment. [Figure 2] FIG. 2 is a vertical cross-sectional view of a first reference example. [Figure 3] FIG. 10 is a vertical cross-sectional view of a second reference example. DETAILED DESCRIPTION OF THE INVENTION

[0017] Next, an embodiment of the present invention will be described with reference to the drawings. In the following, the terms "front-rear" and "left-right" are used to specify directions, but the front-rear direction is the crankshaft axis direction, and the left-right direction is the direction perpendicular to the crankshaft axis and the cylinder axis.

[0018] (1). fruit Structure of the embodiment figure Shown in 1 Sumi An embodiment will now be described. The engine is a multi-cylinder type for a vehicle, and has, as its engine body, a cylinder block 1 and a cylinder head 2 fixed to its upper surface. A plurality of cylinder bores 3 are formed in the cylinder block 1, aligned in the front-rear direction, and a piston 4 is slidably fitted into each cylinder bore 3. The piston 4 is connected to a crankshaft (not shown) via a connecting rod 5. Note that a gasket is interposed between the cylinder head 2 and the cylinder block 1, but is not shown in the figure.

[0019] A mountain-shaped (pent roof-shaped) recess 6 that opens toward each cylinder bore 3 is formed in the underside of the cylinder head 2, and a pair of intake ports 7 and a pair of exhaust ports 8 (front and rear) open into the recess 6, separated into left and right sides when viewed from the crankshaft direction. A pair of front and rear intake valves 9 that open and close the outlet of the intake port 7, and a pair of front and rear exhaust valves 10 that open and close the inlet of the exhaust port 8 are slidably mounted on the cylinder head 2 via valve guides (bushes) 11, respectively.

[0020] The intake valve 9 and exhaust valve 10 are biased in the closing direction by a spring 12, and their upper ends abut against cam lobes on camshafts 14 and 15 via valve caps 13. Therefore, although the valves 9 and 10 in this embodiment are of the direct-push type, a system in which they are driven via rocker arms can also be used. The intake valve 9 and exhaust valve 10 are inclined with respect to the cylinder axis so that the distance between them increases as they go up when viewed from the crankshaft direction, but a type in which they are parallel to the cylinder axis can also be used.

[0021] Although not shown in the figure, the camshaft is rotatably held by a cam cap, and the valve train is covered by a head cover 16. The outer periphery of the head cover 16 is fixed with bolts to the outer periphery of the cylinder head 2. A sealant is placed between the head cover 16 and the cylinder head 2.

[0022] Each intake port 7 opens to the intake side surface 2a of the cylinder head 2, and each intake port 7 is connected to a branch pipe of an intake manifold 17 fixed to the intake side surface 2a of the cylinder head 2. Note that it is also possible to employ a type in which a pair of front and rear intake ports 7 branch off from a single collection port, and a single branch pipe of the intake manifold 17 is connected to the collection port.

[0023] The exhaust ports 8 open on 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, but it is also possible to form an exhaust collection section inside the cylinder head 2 and connect a single exhaust pipe or exhaust turbocharger to a single exhaust outlet hole.In addition, since the exhaust gas from a hydrogen engine is water vapor, no catalyst is required to purify the exhaust gas.

[0024] A center hole 19 that is open at the top and bottom is formed in the cylinder head 2 above the approximate center of each recess 6, and a fuel injection valve (injector) 20 that atomizes hydrogen fuel (liquid hydrogen) and injects it into the combustion chamber is disposed in this center hole 19. Therefore, the engine of this embodiment is a direct injection type. The fuel injection valve 20 is disposed concentrically with the cylinder axis, but it may be disposed offset in the left-right or front-rear direction, or tilted relative to the cylinder axis.

[0025] The upper part of the fuel injection valve 20 is configured as a control unit 21 with a built-in electromagnetic solenoid, etc., and liquid hydrogen is sprayed into the combustion chamber in an atomized (gasified) state from a nozzle 22 at the lower end. Hydrogen fuel is supplied from a delivery pipe 31 located near the control unit 21.

[0026] A cable 23 is connected to the control unit 21, and the cable 23 is drawn out to the outside via a connector 24 provided on an upper cover 16b fixed to the head cover 16. The connector 24 is attached to the upper cover 16b in a completely sealed state.

[0027] An ignition plug 25 is mounted in the cylinder head 2 below the intake port 7 with its electrode exposed in the recess 6. Therefore, the ignition plug 25 is disposed in an inclined position with its axis tilted significantly.

[0028] To provide additional information about the drawings, in Figure 1 (and Figure 2), both the fuel injection valve 20 and the intake and exhaust ports 7, 8 are shown with solid lines, but because there are a pair of intake and exhaust ports 7, 8 in the front and rear, when cut on a single plane, the fuel injection valve 20 and the intake and exhaust ports 7, 8 do not appear together. Therefore, in Figure 1, the area where the fuel injection valve 20 is provided and the area where the intake and exhaust ports 7, 8 are provided are cut on planes that are offset in the front-to-rear direction.

[0029] 1, the spark plug 25 is shown as being positioned below one intake port 7, but in reality, the spark plug 25 is located below a portion between the front and rear intake ports 7. Therefore, in reality, the spark plug 25 is positioned higher than in the state shown in FIG. 1. Although not indicated by a reference number, the cylinder head 2 is formed with a cooling water jacket.

[0030] It is also possible to arrange the fuel injection valve 20 and the spark plug 25 in a vertically elongated position, one behind the other, with their lower ends exposed in the recess 6. In this case, the fuel injection valve 20 and the spark plug 25 can be slightly tilted with respect to the cylinder axis.

[0031] At the portion of the head cover 16 corresponding to each fuel injection valve 20, a downward-facing surrounding frame portion 16a is integrally formed to surround the portion of the fuel injection valve 20 exposed above the cylinder head 2 (mainly the control unit 21) from the outer periphery, and the surrounding frame portion 16a is covered from above by the upper cover 16b already described.

[0032] A lower end 16c of the surrounding frame portion 16a of the head cover 16 is tightly fitted via a sealing means into a cylindrical boss formed on the cylinder head 2, while a flange 16d formed around the entire periphery of the lower edge of the upper cover 16b is fixed with screws via a sealing means to the upper surface of the head cover 16, and the surrounding frame portion 16a and the upper cover 16b form a closed space that surrounds the upwardly exposed portion of the fuel injection valve 20. A hydrogen detection sensor 26 is located on the ceiling surface of the upper cover 16b.

[0033] Therefore, in this embodiment, the surrounding frame portion 16a formed on the head cover 16 and the upper cover 16b separate from the head cover 16 are used to achieve the above-mentioned object. For fuel injection valvesA cover is formed, and part of the head cover 16 doubles as a cover for enclosing the sensor. Needless to say, a cable 27 is connected to the hydrogen detection sensor 26, and the cable 27 is connected to the ECU (engine control unit). The delivery pipe 31 described above is long in the front-to-rear direction and passes through each surrounding frame portion 16a, but it is also possible to connect fuel supply pipes individually to each fuel injection valve 20 without using the delivery pipe 31.

[0034] In the illustrated example, each surrounding frame portion 16a is individually covered by an upper cover 16b, but it is also possible to form the upper cover 16c in a long shape from front to back so that all surrounding frame portions 16a are covered by a single upper cover 16b. In this case, the hydrogen detection sensor 26 may be disposed in one location in the middle of the front to back of the upper cover 16b (or in multiple locations, the number of which is less than the number of fuel injection valves 20).

[0035] (2) Summary Now, since the fuel injection valve 20 is constantly in use while the engine is running, there is a possibility that the sealing performance will gradually deteriorate due to wear over time, and hydrogen fuel will leak to the outside of the fuel injection valve 20. Alternatively, it cannot be said that there is no possibility that hydrogen fuel will leak from the fuel injection valve 20 due to other factors such as an accident.

[0036] Hydrogen is highly flammable and therefore dangerous if it leaks, and it can be said that the most likely source of leakage around the engine is from the fuel injection valve 20. In this embodiment, however, the hydrogen detection sensor 26 is located above the fuel injection valve 20, so that if hydrogen leaks from the fuel injection valve 20, this fact can be detected immediately and an alarm or the like can be issued to notify the driver so that the necessary measures can be taken.

[0037] Specifically, a warning lamp on the driver's seat panel may flash, a voice may be emitted to notify the driver of the leak, or the leak may be displayed on various display monitors or the car navigation monitor along with instructions on how to deal with the leak. One way to deal with the leak is to stop the vehicle in a safe place and contact a service provider. If the leak is minor, it may be possible to drive the vehicle to a service workshop. Another way to deal with a leak is to use a vacuum pump to suck the leak out and return it to the intake port 7.

[0038] In this embodiment, even if hydrogen fuel leaks from the fuel injection valve 20, it will not diffuse to the outside, providing a high level of safety. Furthermore, since hydrogen has a lower specific gravity than air and tends to rise upward, if the upper cover 16b is formed to bulge upward from the head cover 16, as in this embodiment, leaked hydrogen will tend to collect in the upper cover 16b, which has the advantage of improving detection accuracy and further improving safety by eliminating the opportunity for contact with electrical components such as the VVT.

[0039] A small amount of hydrogen fuel may blow into 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 pass through the timing chain arrangement space and enter the valve chamber. Therefore, while the hydrogen contained in the blow-by gas can also be detected by the hydrogen detection sensor 26, it is necessary to distinguish between the presence of hydrogen due to normal driving and the presence of hydrogen that has leaked from the fuel injection valve 20.

[0040] In this regard, it is possible to set in advance a hydrogen concentration value that allows safe operation and a hydrogen concentration that is deemed dangerous, and take measures such as issuing an alarm if the detected hydrogen concentration exceeds a dangerous concentration. Alternatively, the sensitivity of the hydrogen detection sensor 26 can be set to a level that allows it to detect dangerous amounts, but not to react to hydrogen contained in blow-by gas.

[0041] (3). Reference example In Figures 2 and 3 Reference example These are other examples of the positions of the fuel injection valve 20 and the spark plug 25.

[0042] Of these, the one shown in Figure 2 First reference example In the cylinder head 2, a plug hole 28 is provided above each recess 6, and a spark plug 25 is screwed into the plug hole 28, and a cylindrical ignition boss portion 16e provided on the head cover 16 is tightly fitted into the plug hole 28. On the other hand, the fuel injection valve 20 is positioned above the intake port 7 in an inclined position, with the nozzle 22 facing the intake port 7. Therefore, First reference example is a port injection type.

[0043] The fuel injection valve 20 has a flange 29 attached to the body, which is fixed with a screw (not shown) to a seat 30 formed on the cylinder head 2. A delivery pipe 31 extending longitudinally 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.

[0044] this Reference example In this embodiment, a portion of the fuel injection valve 20 partially protrudes toward the intake side of the cylinder head 2, so a protruding main body portion 32 is formed on the intake side of the cylinder head 2 to surround the fuel injection valve 20 from below and the sides, and a protruding lid portion 33 is formed on the head cover 16 to cover the protruding main body portion 32 of the cylinder head 2 from above, and the protruding lid portion 33 is fixed to the protruding main body portion 32 with bolts (not shown). The hydrogen detection sensor 26 is disposed on the underside of the protruding lid portion 33. Therefore, in this embodiment, the protruding main body portion 32 and the protruding lid portion 33 are For fuel injection valves It corresponds to the cover.

[0045] Needless to say, a liquid or solid sealant is interposed between the mating surfaces of the protruding main body 32 and the protruding lid 33. In this embodiment, since the delivery pipe 31 is provided, the protruding main body 32 and the protruding lid 33 are long in the front-to-rear direction. The hydrogen detection sensors 26 may be arranged corresponding to each fuel injection valve 20, or may be arranged in one or more locations without corresponding to each fuel injection valve 20.

[0046] When a fuel supply pipe is individually routed to each fuel injection valve 20 without using a delivery pipe 31, it is possible to form a protruding main body portion 32 and a protruding lid portion 33 for each cylinder. For fuel injection valves It is also possible to create the cover as a separate member and fasten it to the cylinder head 2 with screws.

[0047] If two intake ports 7 corresponding to one cylinder are separated over the entire length, two fuel injectors 20 are required for each cylinder. On the other hand, if two intake ports 7 are separated from one collection point, it is sufficient to inject fuel from one fuel injector 20 toward the collection point.

[0048] As shown in Figure 3 Second reference example is a direct injection type in which the ignition plug 25 is exposed in the center of the recess 6 and the fuel injection valve 20 is exposed in 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.

[0049] And this Reference example In this case, the upper part of each fuel injection valve 20 is exposed to the outside of the cylinder head 2, so that the upper part of the fuel injection valve 20 is surrounded by a longitudinal For fuel injection valves Create cover 34 and For fuel injection valves The cover 34 is fixed to the side of the cylinder head 2. The hydrogen detection sensor 26 For fuel injection valvesIt is disposed on the upper inner surface of the cover 34. The cover 34 is long in the front-to-rear direction because fuel is supplied to the fuel injection valve 20 from the delivery pipe 31. The top surface of the piston 4 is formed with a recess for diffusing the fuel ejected from the fuel injection valve 20.

[0050] Although the embodiments of the present invention have been described above, the present invention can be embodied in various other ways. do. [Industrial Applicability]

[0051] The present invention can be embodied in a hydrogen engine and is therefore industrially applicable. [Explanation of symbols]

[0052] 1 Cylinder block 2. Cylinder head 3 Cylinder bore 4 pistons 6. Recess that forms the combustion chamber 7 Intake port 8 exhaust port 9. Intake valve 10 Exhaust valve 16 Headcover 16a For fuel injection valves The surrounding frame that makes up the cover 16b For fuel injection valves Upper cover that constitutes the cover 20 Fuel injection valve 21 Control Unit 22 nozzles 25 Spark plug 26 Hydrogen detection sensor sa 31 Delivery tube

Claims

1. A reciprocating engine having a combustion chamber that pushes a piston down by burning hydrogen, a cylinder head in which said combustion chamber and an intake port communicating therewith are formed and in which a valve mechanism is arranged, a head cover fixed to said cylinder head so as to cover said valve mechanism, and a fuel injection valve that injects hydrogen fuel into said combustion chamber, the fuel injection valve has a control unit arranged in a space surrounded by the head cover, the control unit is covered by a fuel injection valve cover that is formed integrally with the head cover or that is formed separately from the head cover and fixed to the head cover, and a hydrogen detection sensor is arranged on the inner surface of the fuel injection valve cover. engine.

2. The cover for the fuel injection valve is composed of a surrounding frame portion that is integrally formed to surround the control unit of the fuel injection valve and protrudes toward the cylinder head, and an upper cover that is separate from the head cover and fixed to the head cover.

2. The engine of claim 1.

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