WO2003062623A1

WO2003062623A1 - Gas fuel engine

Info

Publication number: WO2003062623A1
Application number: PCT/JP2003/000391
Authority: WO
Inventors: Hiromitsu Matsumoto; Noboru Sakamoto; Naoki Onda
Original assignee: Yamaha Hatsudoki Kabushiki Kaisha
Priority date: 2002-01-23
Filing date: 2003-01-17
Publication date: 2003-07-31
Also published as: JP2003214258A

Abstract

It comprises a first fuel feed stroke for allowing fuel gas to stay in an intake passageway (5) with an intake valve (15) closed, and a second fuel feed stroke for feeding fuel gas from a gas spout (nozzle 4) in the vicinity of the intake valve (15) into the intake passageway (5) during intake stroke.

Description

Description Gas-fueled engine

Technical field

The present invention relates to a gas fuel engine that supplies gas fuel to an intake passage. Background art

Conventionally, engines using gas fuel adopt a structure in which fuel gas is mixed with air by a mixer and supplied to the intake passage, or, similarly to engines using liquid fuel, fuel gas is injected into the intake passage by an injector. . Unlike gas fuel, gas fuel does not adhere to the wall of the intake passage and stay there.

Is sucked into the cylinder in a state of being widely dispersed in the intake passage

On the other hand, for an engine using liquid fuel, a mixture formed so as to be significantly leaner than the stoichiometric air-fuel ratio is supplied to the entire area inside the cylinder, and the mixture is relatively densely mixed in a narrow area near the periphery of the spark plug. In some cases, air is supplied in a stratified manner to stabilize combustion and improve fuel efficiency.

In order to collect a relatively rich air-fuel mixture in the vicinity of the spark plug in this type of engine, for example, as disclosed in Japanese Patent Application Laid-Open No. Hei 6-2573432, intake air is introduced into a cylinder. In addition to generating an evening flow consisting of a vertical swirling flow, the fuel was injected by an injector toward the branch of the bifurcated intake port. In other words, fuel is injected so as to be directed toward the center of the cylinder, and the fuel sucked into the cylinder rides on the tumble flow and flows through the cylinder.As a result, fuel is collected near the periphery of the spark plug at the center of the cylinder. Be able to The inventors have considered that even in a gas-fueled engine, fuel gas is supplied in a layered manner near the periphery of the ignition plug to achieve lean combustion to improve fuel efficiency. However, since the fuel gas is mixed with air earlier than liquid fuel, it is mixed with air before being sucked into the combustion chamber and is widely dispersed in the intake passage. Could not be supplied.

The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a gas fuel engine capable of realizing lean combustion by supplying a fuel gas into a cylinder in a layered manner. Disclosure of the invention

In order to achieve this object, a gas fuel engine according to the present invention is a gas fuel engine that supplies gas fuel to an intake passage, wherein the first fuel stores fuel gas in the intake passage with the intake valve closed. It has a supply step and a second fuel supply step of supplying fuel gas into the intake passage from a gas injection port near the intake valve in the intake step.

According to the present invention, in the first fuel supply stroke, the fuel gas and the air are mixed in the intake passage to form an air-fuel mixture, and the air-fuel mixture is dispersed in the cylinder in the intake stroke. In addition, the fuel gas newly supplied from the gas injection port to the vicinity of the intake valve in the second fuel supply process does not spread widely by riding on the intake air flowing near the intake valve in the intake process. It is sucked into the cylinder in layers.

A gas fuel engine according to a second aspect of the present invention is the gas fuel engine according to the first aspect of the invention, wherein a swirling flow of intake air is generated in a cylinder, and the fuel gas injected from a gas injection port is provided. Flows near the spark plug by the swirling flow.

According to the present invention, since the fuel gas can be supplied in a layered manner to the vicinity of the ignition plug by the tumble flow, the total supply amount of the fuel gas is made extremely leaner than the stoichiometric air-fuel ratio. With this setting, the concentration of the fuel gas near the periphery of the spark plug can be relatively increased.

A gas fuel engine according to a third aspect of the present invention is the gas fuel engine according to the first aspect, wherein an injector for injecting gas fuel is disposed in an intake passage, and the injector is provided near an upstream of an intake valve. A pipe member having an open end is connected to the pipe member, and the opening of the pipe member is used as a gas injection port.

According to the present invention, the degree of freedom of the position where the gas injection port is provided is increased, and the gas injection port can be provided close to the intake port.

A gas fuel engine according to a fourth aspect of the present invention is the gas fuel engine according to the first aspect, wherein a fuel passage through which gas fuel is injected by an injector is formed in an intake passage wall; A pipe member having a tip opening near the upstream of the intake valve is connected to the downstream end of the pipe member, and the opening of the pipe member is used as a gas injection port.

The gas fuel engine according to the invention described in claim 5 is the gas fuel engine according to the invention described in claim 3 or 4, wherein the injector has a plurality of fuel injection ports, and each injector has a fuel injection port. It has a corresponding tube member. According to the present invention, fuel gas can be supplied to a plurality of intake passages by one injector.

The gas fuel engine according to the invention described in claim 6 is the gas fuel engine according to any one of claims 1 to 5, wherein the gas injection port is connected to the exhaust valve based on the center of the combustion chamber. Are pointing in opposite directions.

According to the present invention, the fuel gas is supplied to a relatively low temperature portion in the cylinder.

The gas fuel engine according to the invention described in claim 7 is the same as that of claims 1 to 5. In the gas fuel engine according to any one of the above aspects, a plurality of intake valves are provided in the cylinder 每, and a gas injection port is provided for each of the intake valves.

According to the present invention, since the fuel gas can be supplied from the plurality of intake outlets into the cylinder, the degree of freedom of the position for supplying the fuel gas is improved. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a sectional view of an engine according to the present invention.

FIG. 2 is an enlarged sectional view showing a part of the engine.

FIG. 3 is a plan view of the piston.

FIG. 4 is a plan view showing a configuration in a state where a portion near the combustion chamber of the engine is viewed from the cylinder head side.

FIG. 5 is a bottom view showing the combustion chamber wall of the cylinder head.

FIG. 6 is a longitudinal sectional view of the cylinder and biston.

FIG. 7 is a sectional view taken along the line VII-VII in FIG.

FIG. 8 is a time chart showing the opening / closing timing of the intake / exhaust valve and the fuel injection timing. FIG. 9 is a sectional view showing another example of the piston.

FIG. 10 is a cross-sectional view of an engine provided with a guide member.

FIG. 11 is a cross-sectional view showing a main part in FIG. 10 in an enlarged manner.

FIG. 12 is a sectional view taken along line XI I-XI I in FIG.

FIG. 13 is a view showing a guide member.

FIG. 14 is an exploded perspective view of the guide member shown in FIG.

FIG. 15 is a diagram showing another example of the guide member.

FIG. 16 is a cross-sectional view of a part of the engine showing another example of the guide member.

FIG. 17 is an enlarged sectional view showing the guide member.

Figure 18 shows the structure of the engine near the combustion chamber when viewed from the cylinder head side. It is a top view showing composition.

FIG. 19 is a schematic diagram for explaining the tumble flow.

FIG. 20 is a bottom view of the fuel gas supply nozzle.

FIG. 21 is a sectional view taken along line AA in FIG.

FIG. 22 is a sectional view taken along line BB in FIG.

FIG. 23 is a cross-sectional view taken along line CC in FIG.

FIG. 24 is an enlarged perspective view showing a guide member and a valve body of an intake valve.

FIG. 25 is a cross-sectional view showing another example of the fuel gas supply nozzle.

FIG. 26 is a plan view showing a configuration in a state where a portion near the combustion chamber of the engine is viewed from the cylinder head side.

FIG. 27 is a sectional view taken along line AA in FIG.

FIG. 28 is a cross-sectional view of the gas fuel engine.

FIG. 29 is a cross-sectional view of the gas fuel engine.

FIG. 30 is a plan view showing a configuration in a state where a portion near the combustion chamber of the engine is viewed from the cylinder head side.

FIG. 31 is a sectional view taken along line AA in FIG.

FIG. 32 is a view on arrow B of the intake valve and the intake outlet in FIG.

FIG. 33 is a cross-sectional view of a gas fuel engine that generates a forward tumble flow using a guide member attached to an intake port.

FIG. 34 is a sectional view taken along line AA in FIG. BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment)

Hereinafter, an embodiment of an engine according to the present invention will be described in detail with reference to FIGS.

1 is a sectional view of an engine according to the present invention, and FIG. 2 is an enlarged view of a part of the engine. In cross section, the figure is drawn with the piston positioned at top dead center during the compression stroke. Fig. 3 is a plan view of the piston, Fig. 4 is a plan view showing the structure near the combustion chamber of the engine viewed from the cylinder head side, and Fig. 5 is a bottom view showing the combustion chamber wall of the cylinder head. It is. Fig. 6 is a vertical sectional view of the cylinder and biston, Fig. 7 is a sectional view taken along the line VII-VII in Fig. 1, Fig. 8 is a time chart showing the opening and closing timing of the intake and exhaust valves and the fuel injection timing, and Fig. 9 FIG. 4 is a sectional view showing another example of the piston.

In these figures, what is indicated by reference numeral 1 is an engine according to this embodiment. The engine 1 is operated using a gas fuel such as LPG or CNG (compressed natural gas). The gas fuel is supplied from a fuel gas supply injector 3 of a cylinder head 2 to a nozzle 4 described later. Injection into the intake passage 5 is carried out. Although the number of cylinders of the engine 1 is shown in FIG. 1 for only one cylinder for convenience of explanation, it can be used for an engine having a plurality of cylinders. In FIG. 1, reference numeral 6 denotes a cylinder body, 7 denotes a piston, and 8 denotes a conrode. As is well known, the cylinder head 2 is provided with a DOHC type valve gear 11 and an ignition plug 12, and has an intake boat 13 and an exhaust which form the intake passage 5. Port 14 is provided.

The valve gear 11 has two intake valves 15 and two exhaust valves 16 for each cylinder, and the intake and exhaust valves 15 and 16 are supplied through valve lifters 17 respectively. It is driven by a camshaft 18 and an exhaust camshaft 19.

The ignition plug 12 is disposed at the center of the cylinder surrounded by the four intake / exhaust valves 15 and 16. The screw holes into which the ignition plugs 12 are screwed are indicated by reference numeral 20 in FIGS. In FIG. 5, reference numeral 21 denotes an intake outlet of an intake port 13 opened and closed by an intake valve 15, and 12 denotes an exhaust inlet of an exhaust port 14 opened and closed by an exhaust valve 16.

In this embodiment, the intake port 13 is provided for each intake valve 15 (see FIG. 4). As shown in FIG. 1, the cylinder head 2 is formed to penetrate the cylinder head 2 in the vertical direction (the direction along the cylinder axis C). Although not shown, a throttle valve is connected to the upstream side of the intake port 13 through an intake passage of a head cover and an intake pipe attached to the head cover.

As shown in FIG. 1, the intake boat 13 according to this embodiment is inclined so as to gradually approach the intake valve 15 from the opening at the upper end of the cylinder head 2 toward the downstream, In addition, an inclined portion 13 is provided which gradually extends to the opposite side to the exhaust valve 16 toward the downstream side.

By forming the intake port 13 in this manner, the intake air that has passed through the intake port 13 flows into the cylinder from the intake outlet 21 in the direction opposite to the exhaust valve 16 due to the inertia of the intake flow. Be guided.

On the other hand, the exhaust port 14 is formed so that the exhaust passage for each exhaust valve 16 merges in the cylinder head 2 and extends to the exhaust outlet 24 on one side of the cylinder head 2.

As shown in FIGS. 1 to 3 and FIG. 6, the biston 7 has a slope 15 and a recess 26 formed on the top 7a. As shown in FIGS. 2 and 4, the slope 25 is formed so as to extend in the direction in which the intake valves 15 are arranged side by side at the top 7 a of the piston 7 opposite to the intake valves 15. The intake valve 15 is inclined so as to be parallel to an end surface 15 c (a surface forming a part of the combustion chamber wall) of the valve body 15 of the intake valve 15.

As shown in FIG. 2 and FIG. 6, the concave portion 26 is formed so that a D-shaped portion in a plan view adjacent to the slope 25 at the top portion 7a of the biston 7 is hemispherically recessed downward. It is formed. As shown in FIG. 9, the piston 7 should be formed so that a portion adjacent to the slope 25 of the top portion 7a is flat and the flat portion 7b is substantially a concave portion 26. Can also. By using this biston 7, the compression ratio can be increased as compared to the case where the biston 7 shown in FIG. 1 is used. The fuel gas supply injector 3 is provided for each cylinder, and is attached to a portion of one side of the cylinder head 2 corresponding to a portion between the intake ports 13. The injector 3 is supplied with fuel gas from a fuel tank (not shown) under pressure, and feeds fuel from a fuel injection port 27 at the tip (see FIG. 7) into a cylinder head 2 at a predetermined fuel injection timing. Fuel gas is injected into passage 28.

As shown in FIG. 8, the fuel injection by the injector 3 is performed when the intake valve 15 is closed during the exhaust stroke (first fuel supply stroke) and when the intake valve 15 is opened during the intake stroke ( In the second fuel supply stroke), the injection time and injection period are set for each of the operating conditions.

The period during which the fuel is injected by the engine 3 is set to be longer during the first fuel supply stroke than during the second fuel supply stroke. As the fuel injection amount, for example, approximately 50 to 70% of the fuel gas supplied in one cycle is injected in the first fuel supply stroke, and the remainder is injected in the second fuel supply stroke.

As shown in FIG. 7, the fuel passages 28 from which the injectors 3 inject fuel extend from the injector mounting holes 29 to the respective intake ports 13 and extend to the downstream end of the intake ports 13. It is constituted by a through-hole 30 of the intake port 13 which opens, and a nozzle 4 made of a pipe fitted and fixed to each of the through-holes 30 from the intake outlet 21 of the intake port 13. ing. As shown in FIG. 4, each nozzle 4 is disposed in the vicinity of an adjacent intake port 13 in the intake port 13 and, as shown in FIG. 1, the opening at the tip is based on the center of the combustion chamber. It is bent in the opposite direction to the exhaust valve 16 so as to point downstream in the direction in which the intake air flows. The nozzle 4 constitutes a pipe member according to the present invention, and the opening at the tip constitutes a fuel injection port according to the present invention. The fuel injection holes 17 of the injectors 3 are provided at portions facing the through holes 30, respectively, and fuel gas is directly injected from the fuel injection holes 27 into the through holes 30. You.

Here, the downstream side of the intake air flow flows through the inclined portion 23 of the intake port 13 This means the downstream side of the intake air whose direction is regulated, and the direction from the intake outlet 21 of the intake port 13 opposite to the exhaust valve 16 and obliquely downward.

By forming the nozzle 4 in this manner, the fuel gas injected into the intake port 3 from the nozzle 4 during the intake stroke is supplied to the intake valve 15 as shown by the solid black arrow G in FIG. The air flows obliquely downward in a direction away from the exhaust valve 16 in the cylinder through a gap between the exhaust valve 16 and the intake outlet 21.

In the engine 1 configured as described above, as shown in FIG. 8, when the piston 7 rises in the exhaust stroke (when the intake valve 15 is closed), the first fuel injection in the injector 3 is performed. Is performed. At this time, the fuel gas stays in the intake port 13 because the intake valve 15 is closed. Then, at the end of the exhaust stroke, just before the piston 7 reaches the top dead center, the intake valve 15 opens, and during the descending stroke after the piston 7 has passed the top dead center, the intake port 13 Fuel gas and fresh air staying in the cylinder are sucked into the cylinder.

The fuel gas flows into the cylinder from almost the entire gap between the intake valve 15 and the intake outlet 21, but is pressed by the intake air drawn obliquely downward into the cylinder from the intake boat 13. Most of the air flows in the same direction as the intake air. The fuel gas and fresh air flow to the lower part of the cylinder along the inner peripheral surface of the cylinder.

As described above, the direction of the intake air sucked into the cylinder hits the concave portion 26 of the piston top P7a, and the flow direction is changed, so that a tumble flow is generated in the cylinder as indicated by an arrow T in FIG. As shown in Fig. 1, this tumble flow is separated from the cylinder head 2 on the intake valve 15 side and the cylinder head on the exhaust valve 16 side from the axis C of the cylinder as viewed from the axis of the camshaft. It is a swirling flow approaching to C2 and is a so-called reverse tumble flow in which the swirling direction is opposite to the generally called tumble flow. By forming the tumble flow in this way, the fuel gas is mixed with the fresh air and diffuses in the cylinder to form a lean air-fuel mixture.

After that, the second fuel injection by the injector 3 is performed during the intake stroke. (See Figure 8). At this time, the fuel gas is injected into the cylinder from the two nozzles 4 through the gap between the intake valve 15 and the intake outlet 21. Since the tumble flow T is formed in the cylinder as described above, the fuel gas turns inside the cylinder so as to ride on the tumble flow T as shown in FIG. Since the nozzles 4 are provided near portions of the two intake ports 13 adjacent to each other, the fuel injected from the nozzles 4 flows in a laminar manner near the spark plugs 12. That is, at the end of the compression stroke, a relatively rich air-fuel mixture is supplied in a stratified manner near the periphery of the spark plug 12.

After the second fuel injection is performed and the intake valve 15 is closed, the piston moves to the compression top dead center, as shown in Fig. 2. The diameter is reduced while turning in the space (combustion chamber 32) formed between the recess 26 of the piston top 7 a and the combustion chamber wall 31 on the cylinder head 1 side. On the other hand, at this time, the air-fuel mixture is pushed out from the gap (squish area) between the slope 25 on the top of the piston 7a and the combustion chamber wall 31 on the side of the cylinder head 2, and a squish flow is generated. I will. This squish flow is indicated by arrow S in FIG.

In FIG. 2, the squish flow S proceeds in the combustion chamber 32 toward the exhaust valve 16 along the combustion chamber wall on the cylinder head 2 side in FIG. Collide with each other near the spark plug 12. In the engine 1, the ignition timing is set so that the ignition by the spark plug 12 is performed during the period when the air-fuel mixture is ejected from the squish area.

When the evening tumbling stream T and the squish stream S collide with each other, the air-fuel mixture is dispersed as a small vortex (Mike mouth Yuichiurensu), and the tumble stream T and the squish stream S are synthesized. The gas flows down to the top 7a side of the biston. For this reason, the growth of the flame nucleus after ignition is promoted by the microturbulence, and the flame spreads to the biston top 7a side, so that the combustion range is rapidly expanded. In the engine 1, fuel gas and air are mixed in the intake passage in the first fuel supply stroke, and this air-fuel mixture is dispersed in the cylinder in the intake stroke.

The fuel gas newly supplied to the vicinity of the intake valve 15 from the gas nozzle of the nozzle 4 in the fuel supply process 2 does not spread widely by riding on the intake air flowing near the intake valve in the intake process. As a result, the fuel gas can be widely dispersed in the cylinder and supplied in a layered manner so as to be relatively dense.

In particular, since the engine 1 can supply the fuel gas in a stratified manner near the spark plug 12 by a tumble flow stack, the total supply amount of the fuel gas is set to be extremely leaner than the stoichiometric air-fuel ratio. However, the concentration of the fuel gas in the vicinity of the spark plug 12 can be relatively increased.

Therefore, despite the lean combustion in which the total supply of fuel gas supplied to the cylinder is significantly reduced compared to the supply at the stoichiometric air-fuel ratio, rapid combustion becomes possible and combustion is improved. And fuel efficiency can be improved. Further, the kinetic energy of the air-fuel mixture is attenuated by the collision of the tumble flow T and the squish flow S, so that the state of the air-fuel mixture after the collision does not change significantly even if the rotation speed or load of the engine 1 changes. For this reason, the above-described phenomenon in which combustion is rapidly performed similarly occurs over a wide operating range, and combustion can be improved over substantially the entire engine operating range.

Furthermore, the flow of the air-fuel mixture in the cylinder (flowing downward in the recess 26 at the top 7a of the piston) continues after ignition, so the initial combustion gas that has grown near the top 7a of the piston 7 The unburned gas is continuously supplied to the portion. For this reason, the initial combustion gas is diffused while being stirred by the unburned gas, and is not kept at a high temperature, so that generation of NOx can be suppressed. It should be noted that even when the EGR amount is increased, the same operation as described above can be achieved, so that fuel efficiency can be improved and N0X can be reduced. Furthermore, the kinetic energy of the air-fuel mixture is attenuated by the collision of the tumble flow T and the squish flow S, so that the air-fuel mixture flows in the gap between the electrodes 12 a and 12 b of the spark plug 12 (see FIG. 2). Since it does not flow at high speed, ignition is stable and the ignition voltage does not need to be high, so that existing ignition devices can be used. In this embodiment, a space (a squish area) in which intake air flows from intake port 13 to the opposite side of exhaust valve 16 in the cylinder to generate a so-called reverse tumble flow in the cylinder to generate squish flow S ) Is formed on the intake valve 15 side where the temperature is relatively low, so that knocking is less likely to occur than when the squish area is formed on the exhaust valve 16 side. In addition, since the opening at the tip of the nozzle 4 (gas injection port) is oriented in the direction opposite to the exhaust valve 16 with respect to the center of the combustion chamber, fuel gas is also supplied to the low-temperature part, and knocking occurs even more. It becomes difficult to do.

In the engine 1, a fuel passage 28 through which gas fuel is injected by the injector 3 is formed in an intake passage wall of the cylinder head 2, and a downstream end of the fuel passage 28 is provided upstream of the intake valve 15. A nozzle 4 having an opening at the tip is connected in the vicinity, and the opening of the nozzle 4 is used as a gas injection port. Therefore, the degree of freedom of the position where the gas injection port is provided is increased, and the nozzle 4 can be provided close to the intake outlet 21. .

Further, since the injector 3 has a plurality of fuel injection ports 27 and the nozzles 4 corresponding to the respective fuel injection ports 27 are provided, the fuel gas is supplied to the plurality of intake passages 5 by one injector 3. can do.

Furthermore, in the engine 1, the opening at the tip of the nozzle 4 (gas injection port) is oriented in the opposite direction to the exhaust valve 16 with respect to the center of the combustion chamber, so that the temperature in the cylinder becomes relatively low. The fuel gas is supplied to the part, and the occurrence of knocking can be suppressed.

In addition, since the engine 1 is provided with a plurality of intake valves 15 for each cylinder and an opening (gas injection port) at the end of the nozzle 4 for each of the intake valves 15, a plurality of intake valves are provided in the cylinder. The fuel gas can be supplied from the intake outlet 21 of the fuel cell, respectively, and the degree of freedom of the position for supplying the fuel gas is improved.

The downstream end of the intake port 13 is provided with a sloping portion 23 that gradually extends toward the opposite side from the exhaust valve 16 toward the downstream side, so that a reverse tumble flow is formed. Since the flow direction is regulated, the intake resistance is reduced and the number of parts can be reduced as compared with the case where a member for changing the flow direction of the intake air is provided in the intake port 13.

(Second embodiment)

In order to generate a tumble flow, the guide member shown in FIGS. 10 to 15 can be attached to the intake port.

FIG. 10 is a cross-sectional view of an engine provided with a guide member, FIG. 11 is a cross-sectional view showing an enlarged part of FIG. 10, FIG. 12 is a cross-sectional view taken along line XI I-XI I in FIG. 13 is a view showing the in-vehicle member, FIG. (A) is a cross-sectional view in a state of being assembled to the intake port, FIG. (B) is a side view, and (b) is (a) The fracture position in the figure is indicated by the line A-A. Fig. 13 (c) Fig. (A) is a sectional view taken along the line C-C in Fig. (A), Fig. 13 (d) shows a free state before mounting, and Fig. 13 (b) shows a state in which the diameter is reduced during mounting. FIG. 14 is an exploded perspective view of the guide member shown in FIG. 13, FIG. 15 is a view showing another example of the guide member, FIG. 14 (a) is a plan view, FIG. 14 (b) is a side view, (C) and (a) are cross-sectional views taken along the line C-C in FIG. (A), and FIG. (D) is a plan view showing a state where the diameter is reduced at the time of mounting. In these drawings, the same or equivalent members as those described with reference to FIGS. 1 to 9 are denoted by the same reference numerals, and detailed description will be appropriately omitted.

As shown in FIG. 10, the engine 1 according to this embodiment is different from the engine 1 shown in the first embodiment except that an intake port 13 is provided with a guide member 41 described later. It has an equivalent configuration.

As shown in FIGS. 13 and 14, the guide member 41 is constituted by a C-shaped fixing ring 42 and a shroud 43 welded to the ring 42. The ring 42 is made of a spring material, and can be engaged with a concave groove 44 (see FIG. 11) formed at the downstream end of the intake port 13 by its own elastic force. It is formed in. Hooks 45 for attaching a tool (not shown) are integrally formed at both ends of the ring 42.

The shroud 43 includes a support plate 46 curved in an arc shape in plan view along the inner peripheral surface of the ring 42, and a fan-shaped shroud body 4 integrally formed on the support plate 46. It is composed of 7 and. The support plate 46 is formed with an opening 48 through which the hook 45 of the ring 42 is inserted. When the hook 45 is passed through the opening 48, the inside of the ring 42 is formed. One end is welded to the ring 42 over the periphery. The welding area between the support plate 46 and the ring 42 is indicated by the symbol W in Fig. 13 (a).

The shroud 43 is inclined so as to gradually extend downward (downstream of the intake air flow) from the support plate 46 toward the center of the ring 42, and is curved so as to form part of a conical surface. are doing.

The guide member 41 is disposed such that the lower end of the shroud 43 faces the intake valve 15 in a closed state with a clearance.

The guide member 41 thus formed is attached to the intake port 13 before the intake valve 15 is attached to the cylinder head 2. More specifically, first, as shown in FIG. 13 (d), the hooks 45 of the ring 42 of the guide member 41 in the free state are sandwiched between tools such as pliers (not shown) to spring the ring 42. The guide member 41 is inserted into the intake port 13 from the combustion chamber side by reducing the diameter by staking the force {see FIG. 13 (e)}. Then, the hook 45 is released while the ring 42 is engaged with the concave groove 44 of the intake port 13. At this time, the guide member 41 is positioned so that the shroud 43 is located on the exhaust valve 16 side. By releasing the tool, the ring 42 expands with its own elastic force and is fixed to the intake port 13 (cylinder head 2). The guide member 41 shown in FIGS. 10 to 14 is formed so that the hook 45 of the ring 42 is positioned on the shroud 43, but the guide member 41 is shown in FIG. It can also be formed as follows.

A guide member 41 shown in FIG. 15 has a support plate 46 of a shroud 43 welded to an inner peripheral portion 42 a of the ring 42 facing the hook 45.

The ring 42 of the guide member 41 is attached to the intake port 13 with a reduced diameter as shown in FIG. 15 (d) from the free state shown by the solid line in FIG. 15 (a). After mounting, the ring 42 is reduced in diameter from the free state as shown by the two-dot chain line in FIG. 7A, and is fixed to the intake port 13 by its own elastic force.

By forming the guide member 41 in this manner, the hook 45 can be visually recognized from below, so that the position of the hook 45 can be easily confirmed when the hook 45 is sandwiched by pliers or the like. The assembly work becomes easy. The mounting position of the guide member 41 is the same as that of the guide member 41 shown in FIGS.

By providing the guide member 41 shown in FIGS. 10 to 15 at the intake port 13, the inclined portion 23 of the intake port 13 is substantially extended by the shroud 43, The intake air flowing into the exhaust valve 16 from the gap between the intake valve 21 and the intake outlet 21 can be reduced. As a result, the tumble flow T can be generated more strongly.

Therefore, since the strength of the tumble flow T can be changed by the guide member 41, the tumble flow T is generated by the guide member 41 so that the strength becomes optimum with respect to the generated squish flow S. Therefore, it is possible to surely generate a microturbulence. Therefore, the combustion can be further improved.

(Third embodiment)

The guide member can be formed as shown in FIGS.

FIG. 16 is a cross-sectional view of a part of an engine showing another example of the guide member, and FIG. 17 is a guide member. FIG. 18 is a plan view showing a configuration of a portion near the combustion chamber of the engine viewed from the cylinder head side, FIG. 19 is a schematic diagram for explaining a tumble flow, FIG. 20 is a bottom view of the fuel gas supply nozzle, FIG. 21 is a sectional view taken along the line A—A in FIG. 16, FIG. 22 is a sectional view taken along the line B—B in FIG. 16, and FIG. FIG. 3 is a cross-sectional view taken along the line CC of FIG. FIG. 24 is an enlarged perspective view showing a guide member and a valve body of an intake valve.

In these drawings, members that are the same as or similar to those described with reference to FIGS. 1 to 15 are denoted by the same reference numerals, and detailed description is omitted as appropriate.

The engine 1 shown in FIGS. 16 to 24 has a guide member 51 provided on an intake valve 15. As shown in FIG. 24, the guide member 51 is formed of a metal plate that forms a part of a cone, and is welded to the upper surface of the valve body 15 b of the intake valve 15.

The shape of the guide member 51 will be described in more detail. As shown in FIG. 22, the guide member 51 is formed in a fan shape in plan view that becomes wider as it goes upward, and as shown in FIG. In addition, the intake valve 15 is inclined so as to be unevenly distributed radially outward of the intake valve 15 as it goes upward in a side view. As shown in FIGS. 17 and 18, the guide member 51 is attached to the intake valve 15 on one side of the intake valve 15 adjacent to the exhaust valve 16. As shown in the figure, the center of the arc of the inner surface 51 a of the guide member 51 is positioned so as to substantially coincide with the axis of the intake valve 15.

As shown in FIGS. 16 and 17, the height of the guide member 51 is such that when the intake valve 15 is opened, the upper end faces upstream from the intake outlet 21 of the intake port 13, As shown by the two-dot chain line in FIG. 17, even when the intake valve 15 is closed, the upper end is set so as not to contact the inner wall surface of the intake port 13.

In this embodiment, in order to prevent the intake valve 15 from rotating around the valve stem 15 a and changing the position of the guide member 51 with respect to the intake boat 13, FIG. As shown in 23, the valve stem 15a is formed in a square cross section At the same time, this rectangular section is slidably engaged with the valve stem guide 5 on the cylinder head 2 side.

As shown in FIG. 16, the intake port 13 of the cylinder head 2 according to this embodiment has one side 2 a of the cylinder head 2 as often used in a general engine 1. , And extend obliquely toward the combustion chamber 32. The intake port 13 is formed so that the intake passage 5 is branched into branch passages 5a and 5b for each intake valve 15 in the middle.

When the intake port 13 is formed in this manner, a large amount of intake air flows into the central portion of the combustion chamber 23 due to inertia when the intake valve 15 is opened, but according to this embodiment, Most of the intake air hits the guide member 51, and the flow direction is changed. That is, since the intake air flows in the direction opposite to the exhaust valve 16 by hitting the guide member 51, the engine 1 also has the same internal cylinder as in the first and second embodiments. A reverse evening tumbling occurs.

As described above, since the intake port 13 extends obliquely from the side of the cylinder head 2 as described above, the nozzle 4 for supplying the fuel gas is supplied from one side 1a of the cylinder head 2 through the intake port. It is formed so as to extend to the vicinity of the valve 15. That is, the injector 3 is disposed in the intake passage 5, and the injector 3 is connected to the nozzle 4 having an open end near the upstream of the intake valve 15.

As shown in FIGS. 20 and 21, the nozzle 4 according to this embodiment includes pipes 4 a, 4 a for each intake valve 15, and pipes connecting the upstream ends of the pipes 4 a, respectively. And a holder 4b. As in the case of the first and second embodiments, the pipe 4a has a downstream end disposed near the adjacent intake port 13 in the intake port 13 and flows the intake air. The downstream end in the direction is bent so that the opening at the tip is directed, and the upstream end extends in the intake port 13 to the upstream side along the intake port upper wall 13a (see Fig. 16). Let me.

As shown in FIG. 20, the nozzle holder 4b is provided with a fuel passage communicating with the pipe 4a. A charge passage 4c is bored for each pipe, and is fixed to the intake port upper wall 13a by fixing bolts 53 as shown in FIG. The cylinder head 2 according to this embodiment has a through hole 5 4 for tool passage in the lower wall 13 b of the intake port so that the fixing bolt 53 can be easily attached and detached by a tool (not shown). Are drilled. In FIG. 16, the reference numeral 55 provided at the open end of the through hole 54 is a plug member for closing the through hole 54.

The fuel passage 4c of the pipe holder 4b is opened at the upstream end of the pipe holder 4b, and injects fuel gas from the fuel gas injector 3 mounted on the cylinder head 2.

Even when the guide member 51 and the cylinder head 2 are configured as shown in this embodiment, the same effects as those in the first and second embodiments can be obtained.

In the engine 1, the injector 3 is disposed in the intake passage 5, and the injector 3 is connected to a nozzle 4 having an open end near the upstream of the intake valve 15, and the opening of the nozzle 4 is connected to the gas. Since the gas injection port is used, the degree of freedom in the position where the gas injection port is provided is increased, and the gas injection port can be provided close to the intake port 12.

(Fourth embodiment)

When the intake port is formed to extend obliquely to the cylinder head, a fuel gas supply nozzle can be formed as shown in FIGS. 25 to 27. FIG. 25 is a cross-sectional view showing another example of a fuel gas supply nozzle, and FIG. 26 is a plan view showing a configuration near the combustion chamber of the engine viewed from the cylinder head side. FIG. 26 is a sectional view taken along line AA in FIG. 25. In these figures, the same or equivalent members as those described with reference to FIGS. 1 to 24 are denoted by the same reference numerals, and detailed description will be appropriately omitted.

The fuel gas supply nozzle 4 shown in FIGS. 25 to 27 is composed of a pipe provided for each intake valve 15, and is inserted into the fuel gas supply through-hole 61 of the cylinder head 2 from the intake port 13 side. And is located near the adjacent intake port 13 in the intake port 13. Has been established. Further, as shown in FIG. 25, these nozzles 4 are bent so that the opening at the tip thereof is directed to the downstream side in the direction in which the intake air flows.

The fuel gas supply through hole 61 is a first gas hole extending obliquely and linearly along the intake port 13 from above the inlet of the intake port 13 on one side 2 a of the cylinder head 2. 62, and second gas holes 63 extending from the downstream end of the first gas holes 62 to the intake ports 13 of the respective intake valves 15 (see FIG. 27). I have. The nozzle 4 is mounted on the second gas hole 63. Further, as shown in FIG. 16, the upstream end of the first gas hole 6 is opened inside a hole 29 for mounting a fuel gas supply injector 3 (not shown).

By forming the nozzle 4 in this manner, the fuel gas injected from the nozzle 4 into the intake port 13 during the intake stroke is supplied to the intake valve 1 as shown by the black arrow G in FIG. The gas flows obliquely downward in the opposite direction to the exhaust valve 16 in the cylinder through the gap between 5 and the intake outlet 21.

(Fifth embodiment)

The tumble flow generated in the cylinder may be a normal tumble flow as shown in FIGS. 28 to 34.

Figures 28 and 29 are cross-sectional views of a gas fuel engine that generates a forward tumble flow by providing a guide member on the intake valve.Figure 28 shows the state during the intake stroke, and Figure 29 shows the piston. The state where it is located at the compression top dead center is shown. FIG. 30 is a plan view showing the configuration of a portion near the combustion chamber of the engine viewed from the cylinder head side, FIG. 31 is a cross-sectional view taken along line AA in FIG. 28, and FIG. FIG. 8 is a view of the intake valve and the intake outlet in FIG. FIG. 33 is a cross-sectional view of a gas fuel engine that generates a forward tumble flow using a guide member attached to an intake port, and FIG. 34 is a cross-sectional view taken along line AA in FIG. In these drawings, the same reference numerals are given to the same or similar members as those described in the above-mentioned drawings to the drawings, and the detailed description is omitted as appropriate.

The intake port 13 of engine 1 shown in Fig. 28 to Fig. 32 is connected to the cylinder head 2 It is formed so as to extend obliquely from one side 2 a toward the combustion chamber 32. Further, the intake port 13 is formed so that the intake passage 5 is branched into branch passages 5a and 5b of the intake valve 15 # on the way. Therefore, most of the intake air flowing through the intake port 13 in the intake stroke flows obliquely from the intake outlet 21 to the exhaust valve 16 side in the cylinder due to the inertia of the intake flow.

The intake valve 15 has a guide having a structure similar to that of the guide member 51 shown in the third embodiment in order to prevent the intake air from flowing from the intake outlet 11 in the opposite direction to the exhaust valve 16. A member 71 is provided. The guide member 71 is formed of a metal plate that forms a part of a cone, and is welded to the upper surface of the valve body 15 b of the intake valve 15.

The guide member 71 is formed in a fan shape in plan view (see FIG. 31) whose width increases as it goes upward, and as shown in FIGS. , The intake valve 15 is inclined so as to be unevenly distributed radially outward of the intake valve 15. The position where the guide member 71 is attached to the intake valve 15 is located on one side of the intake valve 15 opposite to the exhaust valve 16, and as shown in FIG. The center of the arc of the inner surface 71 a is positioned so as to substantially coincide with the axis of the intake valve 15.

As shown in FIGS. 28 and 29, the height of the guide member 71 is such that when the intake valve 15 opens, the upper end faces upstream from the intake outlet 21 of the intake port 13, Even if the intake valve 15 is closed, the upper end is set so as not to contact the inner wall surface of the intake port 13.

Also in this embodiment, in order to prevent the intake valve 15 provided with the guide member 71 from rotating, as in the case of the third and fourth embodiments, the intake valve 15 The valve stem 15a is slidably engaged with the valve stem guide 52.

In the engine 1, the intake air flows obliquely into the cylinder from the intake port 13 to generate a tumble flow composed of the swirling flow of the intake air in the cylinder. . As shown by an arrow T in FIG. 28, this tumble flow is a so-called forward tumble flow in which the swirling direction is opposite to that shown in the above-described first to fourth embodiments. For this reason, in the engine 1, the squish flow S and the tumble flow stack are swirled in the same direction in the combustion chamber 32 at the end of the compression stroke.

When the engine 1 is configured to generate the forward tumble flow, the pipe 4a of the fuel gas supply nozzle 4 is formed linearly so as to extend in the same direction as the direction in which the intake air flows.

The nozzle 4 is disposed at a position adjacent to the adjacent intake port 13 in the intake port 13, and as shown in FIG. 32, with the intake valve 15 open, the intake valve 15 and the intake The fuel gas is positioned so as to be injected into the cylinder through the gap between the fuel gas and the fuel gas. As in the case of the first to fourth embodiments, the fuel gas is supplied to the first fuel supply stroke when the intake valve 15 is closed, and to the fuel gas when the intake valve 15 is open. The fuel is injected from the nozzle 4 during the second fuel supply stroke.

The gas fuel engine 1 shown in FIG. 33 has a guide member 81 equivalent to the guide member 41 shown in the second embodiment at the intake port 13. Reference numeral 82 denotes a ring of the guide member 81, reference numeral 83 denotes a shroud, reference numeral 84 denotes hooks at both ends of the ring 82, and reference numeral 85 denotes an opening through which the hook 84 passes. The guide member 81 is fixed to the intake port 13 so that the shroud 83 is located on the opposite side of the exhaust valve 16 across the intake valve 15.

Thus, even if the guide member 81 is provided in the intake port 13, the same effect as when the embodiment shown in FIGS. 28 to 32 is adopted can be obtained. Industrial applicability

As described above, according to the present invention, in the first fuel supply stroke, the fuel gas and the air are mixed in the intake passage to form an air-fuel mixture, and the air-fuel mixture is dispersed in the cylinder in the intake stroke. . Also, in the second fuel supply stroke, the gas injection port The newly supplied fuel gas is sucked into the cylinder in a stratified state without spreading widely so as to ride on the intake air flowing near the intake valve during the intake stroke.

Therefore, the fuel gas can be widely dispersed in the cylinder so as to be relatively lean, and can be supplied in a layered manner so as to be relatively dense near the ignition plug. And reduce fuel consumption in gas fueled engines.

According to the second aspect of the present invention, the fuel gas can be supplied in a stratified manner to the vicinity of the ignition plug by the tumble flow, so that the total supply amount of the fuel gas is significantly reduced from the stoichiometric air-fuel ratio. Even if it is set, the concentration of the fuel gas near the periphery of the ignition plug can be relatively increased. For this reason, gas fuel engines can improve fuel efficiency while stabilizing combustion.

According to the third aspect of the present invention, the degree of freedom of the position where the gas injection port is provided is increased, and the gas injection port can be provided close to the intake outlet, so that the fuel gas can be supplied to the combustion chamber without diffusing. Can promote the stratification of fuel gas

According to the invention described in claim 4, the degree of freedom of the position where the gas injection port is provided is increased, and the gas injection port can be provided close to the suction outlet, so that the fuel gas can be supplied to the combustion chamber without diffusing. Can promote the stratification of fuel gas

According to the invention described in claim 5, fuel gas can be supplied to a plurality of intake passages with one injector, and cost can be reduced as compared with a case where injectors are provided for each intake passage.

According to the invention as set forth in claim 6, since the fuel gas is supplied to a portion in the cylinder where the temperature is relatively low, occurrence of knocking can be suppressed.

According to the invention as set forth in claim 7, since the fuel gas can be respectively supplied from the plurality of intake outlets into the cylinder, the degree of freedom of the position for supplying the fuel gas is improved, and the fuel gas can be easily supplied. It can be supplied in layers.

Claims

The scope of the claims

1. In a gas fuel engine that supplies gas fuel to the intake passage, a first fuel supply stroke in which fuel gas is stored in the intake passage with the intake valve closed, and a gas injection port near the intake valve in the intake stroke. A gas fuel engine having a second fuel supply step of supplying fuel gas into the intake passage.

2. The gas fuel engine according to claim 1, wherein a swirling flow of the intake air is generated in the cylinder, and the fuel gas injected from the gas injection port flows near the ignition plug by the swirling flow. Fuel engine.

3. The gas fuel engine according to claim 1, wherein an injector for injecting gaseous fuel is arranged in an intake passage, and a pipe member having a tip opening near the upstream of an intake valve is connected to the injector. A gas fuel engine having the opening as a gas injection port.

4. The gas fuel engine according to claim 1, wherein a fuel passage through which gas fuel is injected by an injector is formed in an intake passage wall, and a pipe having a distal end opening near the upstream of an intake valve at a downstream end of the fuel passage. A gas fuel engine which connects members and uses the opening of the pipe member as a gas injection port.

5. The gas fuel engine according to claim 3, wherein the injector has a plurality of fuel injection ports, and includes a pipe member corresponding to each of the fuel injection ports.

6. The gas fuel engine according to any one of claims 1 to 5, wherein the gas injection port points in a direction opposite to the exhaust valve with respect to a center of the combustion chamber.

7. The gas fuel engine according to claim 1, wherein a plurality of intake valves are provided for each cylinder, and a gas injection port is provided for each of the intake valves.