JPH1054242A - In-cylinder injection engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mount an injector on a side of an intake port side of a combustion chamber in a spark ignition type in-cylinder injection engine having an injector for injecting fuel into a combustion chamber for stratified combustion. In addition to securing space, intake ports are rationally arranged without increasing intake resistance. SOLUTION: An intake / exhaust valve is arranged so that an inclination angle θ1 of a valve axis of an intake valve 10 with respect to a cylinder bore axis is smaller than an inclination angle θ2 of a valve axis of an exhaust valve 11, and an intake port at a ceiling portion of a combustion chamber 5 is provided. The wall surface on the opening side and the wall surface on the exhaust port opening side are formed so as to be orthogonal to the above-mentioned respective valve axes, and an injector 15 is provided below the cylinder head 1 on the side of the combustion chamber on the intake port opening side.
The intake ports 6 and 7 extending from the combustion chamber 5 toward the upper side of the cylinder head 1 are formed in a portion between the injector 15 and the intake valve shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct injection type engine having an ignition plug and an injector for directly injecting fuel into a combustion chamber for stratified combustion.

[0002]

2. Description of the Related Art Conventionally, in a spark ignition type engine equipped with a spark plug, an injector is provided so as to face a combustion chamber in order to improve fuel efficiency by stratified combustion, and fuel is directly injected from the injector into the combustion chamber. An in-cylinder injection engine designed to perform this operation is known. For example, in an engine disclosed in Japanese Patent Application Laid-Open No. 6-81651, a combustion chamber is formed between an upper surface of a piston inserted into a cylinder bore of a cylinder block and a lower surface of a cylinder head opposed thereto, and a ceiling of the combustion chamber is formed. An intake port and an exhaust port are opened at the intake port, an intake valve and an exhaust valve for opening and closing these ports are provided, and a spark plug facing a substantially central portion of the combustion chamber is provided. The injector is arranged so that the tip of the injector faces the combustion chamber from near the periphery of the combustion chamber.

In this engine, the ceiling of the combustion chamber on the lower surface side of the cylinder head is of a pent roof type in which the wall surface on the intake port opening side and the wall surface on the exhaust port opening side are inclined substantially symmetrically with the top part interposed therebetween. The valve axis of the valve and the exhaust valve are orthogonal to the wall surface on the intake port side and the wall surface on the exhaust port side, that is, both valve axes are arranged on both sides of the cylinder bore axis in a substantially symmetrically inclined state.

It is desirable that the injector be disposed on the side of the intake port of the combustion chamber in order to avoid thermal influence from the exhaust side. In the example shown, an injector is arranged at the lower side of the intake valve side, and the tip of the injector faces the peripheral portion of the wall surface on the intake port opening side in the combustion chamber ceiling, while the intake port In order to avoid the valve shaft of the intake valve and the portion where the injector is located below the intake valve, the upstream side extends upward above the valve shaft of the intake valve, and is connected to the intake manifold above the cylinder head.

[0005]

In the above-mentioned engine, the combustion chamber is of a pent roof type, and an opening of an intake port is disposed on one side of a ceiling of the combustion chamber. Although the tip of the injector faces the outer periphery of the cylinder bore, in such a combustion chamber structure, if the opening area of the intake port is increased, sufficient space for facing the tip of the injector cannot be obtained.
There is a problem that the opening area of the intake port is reduced in order to secure the arrangement space for the tip of the injector.

Although the upstream portion of the intake port extends upward from the valve axis of the intake valve, it is difficult to generate a swirl (lateral vortex) in the combustion chamber with such a port arrangement. In addition, the turbulence generation is restricted to tumble, and the intake manifold connected to the intake port protrudes above the cylinder head, so that the overall height of the engine increases, which hinders downsizing.

From the viewpoints of swirl generation and the layout of the intake system, it is desirable that the upstream portion of the intake port be disposed so as to extend below the valve axis of the intake valve. However, the combustion chamber is of a pent roof type. In the engine, since the valve axis of the intake valve is relatively greatly inclined with respect to the cylinder bore axis, it is space-saving to dispose the injector and the intake port below the portion where the valve axis of the intake valve is provided. If it is attempted to arrange the intake port, the intake port is bent so as to avoid the injector, thereby causing a problem such as an increase in intake resistance.

In view of the above circumstances, the present invention secures a space for mounting an injector on the side of the combustion chamber on the side of the intake port, and rationally arranges the intake port without increasing intake resistance. It is an object of the present invention to provide an in-cylinder injection engine capable of performing stratified combustion effectively.

[0009]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a combustion chamber having a combustion chamber formed between an upper surface of a piston disposed in a cylinder bore and a lower surface of a cylinder head opposed thereto. An intake port and an exhaust port that open to the chamber are formed in the cylinder head, and an intake valve and an exhaust valve that open and close the intake port and the exhaust port, an injector that injects fuel into the combustion chamber, and a spark plug are provided in the cylinder head. In the arranged direct injection type engine, these valves are arranged so that the inclination angle of the valve axis of the intake valve with respect to the cylinder bore axis is smaller than the inclination angle of the valve axis of the exhaust valve. When the wall surface and the wall surface on the exhaust port opening side are formed so as to be orthogonal to the valve axis of the intake valve and the valve axis of the exhaust valve, respectively. In addition, an injector is arranged at a lower portion of the cylinder head on the side of the combustion chamber on the intake port opening side, and an intake air extending from the combustion chamber toward an upper side of the cylinder head is provided between the injector and the intake valve shaft. A port is formed.

According to this configuration, in the ceiling portion of the combustion chamber on the lower surface side of the cylinder head, the wall surface on the exhaust port opening side inclines to some extent, whereas the wall surface on the intake port opening side has a small inclination. A space for allowing the tip of the injector to face below the section is secured. In this way, an injector mounting space is secured on the side of the cylinder head on the intake port side of the combustion chamber. Further, since the inclination angle of the valve axis of the intake valve is small, a sufficient space for arranging the intake port is obtained between the valve shaft arranging portion and the injector arranging portion of the intake valve. The intake port is formed so as to extend from the combustion chamber toward the upper side of the cylinder head, whereby a port arrangement advantageous for reducing intake resistance and the like is obtained.

In the present invention, if the first intake port for swirl generation and the second intake port for tumble generation are provided in parallel as the above-mentioned intake ports, the swirl and the swirl can be introduced into the combustion chamber in accordance with the operation state and the like. A tumble can be generated.

In particular, the incident angles of the downstream end portions of the first and second intake ports with respect to the combustion chamber are the same,
The second intake port is formed to be shifted above the first intake port on the upstream side of this portion, and an on-off valve linked to each cylinder is provided upstream of the second intake port. Adjustments are made effectively.

That is, to make the inclinations of the valve axes of the two intake valves equal, the incident angles of the downstream end portions of the two intake ports with respect to the combustion chamber are the same.
By shifting both intake ports up and down as described above, a port arrangement suitable for swirl generation by the first intake port and tumble generation by the second intake port is obtained. In this case, since there is a sufficient space between the valve shaft arrangement portion of the intake valve and the injector arrangement portion as described above, such a port arrangement is possible. In addition, since the upstream sides of both ports are vertically displaced, the on-off valves linked to the respective cylinders are easily installed upstream of the second intake port.

Further, in the engine of the present invention, the valve operating mechanism is a DOHC in which both camshafts on the intake valve side and the exhaust valve side are arranged in parallel on the cylinder head, and the height positional relationship of both camshafts in the cylinder bore axis direction. The height of the exhaust valve side camshaft is set lower than the height of the intake valve side camshaft, and the exhaust valve side camshaft is driven by the crankshaft via transmission means, and the intake valve side camshaft is exhausted. If driven by the side camshaft via the interlocking means, it is advantageous to lower the overall height of the engine.

That is, as described above, in response to the difference in the inclination of the valve axis between the intake valve side and the exhaust valve side,
Although the heights of the two camshafts are different, the exhaust valve-side camshaft is driven by the crankshaft via the transmission means, so that the transmission-side means of the transmission-side means is attached to the exhaust-side camshaft at a position lower than the intake-side camshaft. Pulleys and the like are provided, and the engine height in this portion can be kept low.

Alternatively, the valve mechanism is a DOHC in which both camshafts on the intake valve side and the exhaust valve side are arranged in parallel on a cylinder head, and the camshafts on the exhaust valve side are positioned as heights in the cylinder bore axis direction. The height of the shaft is set lower than that of the intake valve side camshaft, the intake valve side camshaft is driven by a crankshaft via a transmission mechanism, and the exhaust valve side camshaft is linked by the intake valve side camshaft. The camshaft drive system is configured to be driven through the means, and the engine is disposed in an engine room below the hood of the vehicle. May be located on the vehicle rear side of the exhaust valve side camshaft.

With this arrangement, the engine height is lower on the front side of the vehicle where the exhaust valve side cam is located than on the rear side of the vehicle where the intake valve side cam is located, and a configuration is obtained that is immediately responsive to the hood line that is lowered forward. .

Further, if the interlocking means between the two camshafts is constituted by a gear, the distance between the camshafts can be reduced, so that the inclination of the valve axis of the intake valve is reduced, so that the intake and the intake are reduced. This is advantageous when the included angle of the valve shaft of the exhaust valve is reduced.

[0019]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a direct injection engine according to an embodiment of the present invention, and FIG. 2 is a schematic plan view of a combustion chamber portion. In these figures, reference numeral 1 denotes a cylinder head installed on a cylinder block 2, and 3 denotes a piston arranged in a cylinder bore 4 of the cylinder block 2, and a combustion is generated between an upper surface of the piston 3 and a lower surface of the cylinder head 1. A chamber 5 is formed, and a concave portion forming the ceiling of the combustion chamber 5 is provided on the lower surface side of the cylinder head 1 in this portion.

The cylinder head 1 has an intake port and an exhaust port opened to the combustion chamber 5, and in this embodiment, two intake ports 6, 7 and two exhaust ports 8, 9 are provided for each cylinder. Is formed. Each intake port 6, 7 is equipped with an intake valve 10, and each exhaust port 8, 9
Are provided with an exhaust valve 11, and the intake valve 10 and the exhaust valve 11 are driven by the cams of the intake valve camshaft 12 and the exhaust valve camshaft 13, respectively. Further, an injector 15 for directly injecting fuel into the combustion chamber 5 and a spark plug 16 are attached to the cylinder head 1.

The intake valve 10 and the exhaust valve 11 have different inclination angles θ1 and θ2 of the valve axis with respect to the cylinder bore axis, and the inclination angle θ1 of the intake valve 10 is smaller than the inclination angle θ2 of the exhaust valve 11. These valves 10, 11
And the wall surface of the combustion chamber 5 on the intake port opening side and the wall surface on the exhaust port opening side are formed to be orthogonal to the valve axis of the intake valve 10 and the valve axis of the exhaust valve 11, respectively. Further, an injector 1 is provided below the cylinder head 1 on the side of the combustion chamber on the intake port opening side.
The intake port 6 is formed at a portion between the injector 15 and the intake valve shaft.

The specific structure of the combustion chamber 5 and the intake ports 6 and 7 is as follows.

Assuming that the direction of the cylinder bore axis is the vertical direction and the direction perpendicular to this (the direction of the mating surface of the cylinder head 1 and the cylinder block 2) is the horizontal direction, the exhaust valve 11
Is relatively inclined to the vertical direction, but the valve axis of the intake valve 10 stands substantially vertically. On the ceiling of the combustion chamber 5, the intake ports 6 and 7 are opened on one side and the exhaust ports 8 and 9 are opened on the other side with the substantially central top part interposed therebetween. 11, an inclined surface having a predetermined angle gradually approaching the lower end surface of the cylinder head (the mating surface with the cylinder block 2) from the top of the center of the combustion chamber. A substantially horizontal plane perpendicular to the valve axis of the valve 10 is provided, and a vertical wall portion 18 is provided between the periphery of the intake port side surface and the lower end surface of the cylinder head.
Is provided. Thus, the shape of the combustion chamber viewed from a cross section orthogonal to the camshafts 12 and 13 is substantially trapezoidal (see FIG. 1).

The injector 15 is attached to the lower portion of the cylinder head 1 on the side of the portion of the combustion chamber 5 on the opening side of the intake port, and the tip end of the injector 15 faces the combustion chamber 5 from the vertical wall portion 18. It is arranged to inject fuel obliquely downward. At least in the low-speed low-load region, the injector 1
From 5 onward, fuel is injected in the late stage of the compression stroke. For example, the compression stroke injection is performed in a low / medium load region in a low / medium speed region, and the fuel injection is performed in an intake stroke in a high load region or a high speed region for uniform combustion. Thus, the injection timing is controlled by a control unit (not shown).

The injector 15 is preferably constituted by a high-pressure swirl injector. This high-pressure swirl injector generates swirl in the spray 25 to promote atomization, and when the injection is performed in the latter stage of the compression stroke when the pressure in the combustion chamber 5 increases, the spray angle becomes 30 degrees.
When the injection is performed in the intake stroke in which the pressure in the combustion chamber 5 is low, the spray angle is wider than in the latter stage of the compression stroke.

A recess 26 is formed on the upper surface of the piston 3 from a substantially central portion thereof to the vicinity of the periphery of the combustion chamber on the side (exhaust side) facing the injector 15. The recess 26 is gradually recessed toward the front side in the injection direction from the injector 15, and the width in the direction orthogonal to the injection direction is larger than the injection width of the injector 15 in the late injection in the compression stroke. In order to correct the tendency that the volume of the combustion chamber increases due to the recess 26 and the compression ratio decreases, a protrusion 27 that protrudes upward is provided on the intake side of the upper surface of the piston 3.

The distance from the tip end of the injector 15 to the end of the combustion chamber where the tip end faces (the end of the recess 26 when the piston 3 is near the top dead center) is defined as the distance from the start of injection in the latter stage of the compression stroke to ignition. It is set to be longer than the spray reaching distance until the time. The ignition plug 16 is disposed at a substantially central portion of a ceiling portion of the combustion chamber, and an ignition gap 16a at a distal end thereof is disposed so as to protrude into the combustion chamber 5 and be interposed in a spray area from the injector 15. In addition, the distance from the tip of the injector 15 to the ignition gap 16a is set smaller than the above-mentioned spray reaching distance.

The upstream side of each of the intake ports 6 and 7 extends obliquely upward through a portion between the injector 15 and the intake valve shaft, and reaches one upper side of the cylinder head 1. An intake manifold 20 having intake passages 21 and 22 corresponding to these ports is connected to the ports 6 and 7.

The first intake port 6 of the two intake ports 6 and 7 is a port for swirl generation, and the second intake port 7
Is a port for generating tumble, both intake ports 6,
7 has the same incident angle with respect to the combustion chamber 5 at the downstream end portion, but the second intake port 7 is shifted above the first intake port 6 upstream of the throat portion. Further, an upstream portion of the second intake port 7 or an intake passage 22 connected thereto.
A swirl control valve (open / close valve) 23 for opening and closing the intake port 7 is provided. The swirl control valves 23 provided for the respective cylinders are interlocked via a common shaft 23a, and are driven by an actuator (not shown).

When the swirl control valve 23 is closed, a swirl (lateral vortex) is generated in the combustion chamber 5 by the intake air from the first intake port 6, and when the swirl control valve 23 is opened, the opening degree is increased. As the size increases, the swirl is weakened and a tumble (longitudinal vortex) is generated by the intake from the second intake port 7.

The swirl control valve 23 is controlled by a control unit (not shown) according to the operation state. For example, as control according to the engine load in the operation region where the compression stroke injection is performed, in a low load region, the swirl control valve 23 is opened to some extent to prevent overspreading and bending of the spray due to swirl. The swirl is relatively weakened, and as the load increases, the opening of the swirl control valve 23 is reduced to increase the swirl. The control according to the engine speed in the operation region where the compression stroke injection is performed includes, as the speed increases, the swirl control valve 23 to decrease the swirl ratio so as to match the increase in the absolute flow rate. The opening is increased.

FIGS. 3 and 4 show a valve operating mechanism for driving intake and exhaust valves of the in-cylinder injection type engine. As shown in these drawings and FIG. 1 described above, the valve mechanism is provided on the cylinder head 1 with both camshafts 1 on the intake valve side and the exhaust valve side.
2, 13 are DOHCs (double overhead camshafts) arranged in parallel.

The height relationship between the camshafts 12 and 13 in the cylinder bore axis direction is such that the height of the camshaft 13 on the exhaust valve side corresponds to the arrangement of the intake and exhaust valves 10 and 11 as described above. The height is set lower than the height of the intake valve side camshaft 12. In other words, although the intake valve 10 and the exhaust valve 11 have substantially the same length of the valve shaft, the inclination of the exhaust valve shaft is larger than that of the intake valve shaft. The two camshafts 12 and 13 are arranged in the above-described height positional relationship corresponding to such a positional relationship between the upper ends of the valve shafts.

In this embodiment, the exhaust valve side camshaft 13 is driven by the crankshaft 30 via the transmission means, and the intake valve side camshaft 12 is driven by the exhaust valve side camshaft via the interlocking means. It is designed to be driven.

More specifically, a crank pulley 31 provided at the front end of the crankshaft 30, a cam pulley 32 provided at the front end of the exhaust valve side camshaft 13, and a timing belt 33 wrapped around them , Idler 34,
The rotation of the crankshaft 30 is transmitted to the exhaust valve side camshaft 13 by a transmission means constituted by a tensioner 35 and the like, and the cam pulley 32 has a pulley diameter twice as large as that of the crank pulley 31 so that the exhaust valve side is rotated. The camshaft 13 rotates at a half speed with respect to the crankshaft 30. Gears 36 and 37 having the same diameter are provided near the front ends of the camshafts 12 and 13 as an interlocking means between the camshafts. 13 rotate in opposite directions at the same speed.

At the front end of the crankshaft 30, an auxiliary device driving pulley 41 is provided in addition to the pulley 31, and an alternator 43, a water pump 44 and the like are provided by an auxiliary device driving belt 42 hung on the pulley 41. Is driven. A distributor mounting portion 45 is provided on the upper side of the cylinder head 1 on the side of the rear end of the exhaust valve side cam shaft 13.
(Not shown) is driven by the exhaust valve side camshaft 13, while the intake valve side camshaft 12
A fuel pump 46 is attached to the side of the rear end, and the fuel pump 46 is driven by the intake valve side camshaft 12 via a belt 47.

The operation of the above-described apparatus according to the present embodiment will be described below.

At least in the operation range on the low-load low-rotation side, the injector 15 sends the combustion chamber 5
Fuel is injected into the inside, and stratified combustion is performed. in this case,
In the present embodiment, the distance from the tip of the injector 15 to the end of the combustion chamber opposed thereto is set to be longer than the spray reaching distance from the start of injection to the ignition timing in the latter half of the compression stroke, and the spray from the injector 15 An ignition gap 16a is interposed in the area and the injector 1
5 is smaller than the above-mentioned spray reaching distance, spray is present at an appropriate concentration around the ignition gap 16a, and ignition stability is ensured. Fuel is prevented from adhering. Therefore, the emission of HC is reduced, and the fuel efficiency and emission performance are improved.

The first intake port 6 for swirl generation
And a second intake port 7 for generating tumble, and a swirl control valve 23 provided for the second intake port 7 is controlled in accordance with an operation state, so that, for example, stratified combustion is performed. Within the operating range, the swirl ratio is increased on the higher load side, and is decreased on the higher rotation side. By such control, stratified combustion is favorably performed.

The injector 15 is disposed on the side of the cylinder head 1 on the side of the intake port of the combustion chamber 5 in order to avoid thermal influence from the exhaust side. Mounting space is secured. That is, the inclination angle of the valve axis of the intake valve 12 with respect to the cylinder bore axis is reduced, the surface of the combustion chamber ceiling on the intake port opening side is substantially horizontal, and the combustion chamber 5 has a substantially trapezoidal cross section. 5
The injector 15 is arranged such that the front end faces a vertical wall portion 18 between the periphery of the surface on the intake port opening side and the lower end surface of the cylinder head. Thus, a space for mounting the injector 15 is secured without reducing the arrangement area of the intake port opening.

The first and second intake ports 6, 7 are effective in the space between the portion of the intake valve 10 where the valve shaft is disposed and the injector 15 located below the cylinder head 1. Are located in Particularly, since the inclination angle of the valve axis of the intake valve 10 with respect to the cylinder bore axis is reduced, the space between the portion where the intake valve shaft is disposed and the injector 15 is widened. The intake ports 6 and 7 are formed so that the upstream side extends obliquely upward and the downstream side is gently bent to reach the combustion chamber 5, so that the intake resistance is sufficiently reduced.

Further, since the intake ports 6 and 7 are vertically shifted such that the second port 7 is located above the first port 6 on the upstream side, the first intake port 6 is moved from the first intake port 6 to the combustion chamber 5. The angle of the inflowing intake air with respect to the horizontal direction is relatively small, and the angle of the intake air flowing into the combustion chamber 5 from the second intake port 7 is relatively large. Therefore, the first intake port 6 and the second intake port 7
Are suitable for swirl and tumble generation, respectively. Further, a swirl control valve 23 is provided in an upstream portion of the second intake port 7 or an intake passage 22 connected thereto, and the swirl control valve 23 of each cylinder is connected by a common shaft 23a. Are displaced up and down on the upstream side, so that the first intake port 6 does not hinder when the swirl control valve 23 and the shaft 23a are mounted.

Further, since the intake ports 6 and 7 are connected to the inlet manifold 20 on the side of the cylinder head 1, as shown in the above-mentioned Japanese Patent Application Laid-Open No. 6-81651, the intake ports 6 and 7 are located above the cylinder head. The height of the engine can be reduced as compared with a structure in which is connected to the inlet manifold.

The valve mechanism is provided on both the intake valve side and the exhaust valve side cam shafts 12 and 13 disposed on the cylinder head 1.
And one of the camshafts is driven by the crankshaft 30 via the transmission means, and the two camshafts 12 and 13 are interlocked via the interlocking means. In the embodiment, the exhaust valve side camshaft 13 is driven by the crankshaft 30,
The overall height of the engine can be reduced.

That is, since the inclination of the valve axis with respect to the cylinder bore axis is larger in the exhaust valve 11 than in the intake valve 10, the upper end position of the valve shaft is closer to the exhaust valve 11 than the intake valve 10 even if the length of the valve shaft is substantially the same. Correspondingly, the positional relationship between the camshafts 12 and 13 is lower on the exhaust valve side camshaft 13 than on the intake valve side camshaft 12. On the other hand, the diameter of the cam pulley 32 in the transmission means is relatively large because the rotation of the camshaft is の of the rotation of the crankshaft 30. When the position of the cam pulley 32 is high, the upper end of the belt cover rises above the cylinder head 1. Greatly protruding,
Although the overall height of the engine is increased, the cam pulley 32 is provided on the exhaust valve side camshaft 13 having a lower height position between the two camshafts 12 and 13, so that the cam pulley is provided on the intake side camshaft. Also the overall height of the engine will be lower.

FIG. 5 shows another embodiment of the present invention. The engine of this embodiment is also an in-cylinder injection engine in which fuel is directly injected from the injector 15 into the combustion chamber 5, and the shape of the combustion chamber and the arrangement of the injector 15 and the intake / exhaust ports are the same as those of the first embodiment. Similarly, the valve operating mechanism is DOHC, one of the camshafts on the intake valve side and the exhaust valve side is driven by the crankshaft 30 via a transmission means, and both camshafts are gears or the like. This is also the same as the first embodiment in that they are linked via the linking means. However, in this embodiment, the intake valve side camshaft 12 of the two camshafts is driven by the crankshaft 30, that is, the intake valve side camshaft 12 is provided with a cam pulley 32 ', , A timing belt 33 is hung.

In this engine, the camshaft extends laterally in the vehicle width direction in the engine room below the hood 50 of the vehicle, and the intake valve-side camshaft 12 is located on the vehicle rear side of the exhaust valve-side camshaft. It is arranged to be located.

According to the present embodiment, the intake valve side camshaft 12 is located higher than the exhaust valve side camshaft in accordance with the difference in the inclination of the valve axis between the intake valve 10 and the exhaust valve 11 as described above. A large-diameter cam pulley 32 is attached to the intake valve side camshaft 12.
Is provided, the belt cover protrudes largely upward on the side where the intake valve side camshaft 12 is located, and the engine height in this portion increases. However, when this engine is arranged in the engine room with the intake valve side camshaft 12 positioned in the rear side of the vehicle, the engine height is higher than that of the vehicle rear side where the intake valve side camshaft 12 is located. Because it becomes lower on the front side of the vehicle where the exhaust valve side cam shaft is located,
The shape conforms to the line of the hood 50 descending forward, so that it fits well in the engine room.

That is, the structure of this embodiment is suitable for a case where the engine is mounted horizontally on a vehicle in which the hood 50 is relatively large and descends forward. On the other hand, the structure of the first embodiment is suitable for a case where the engine is mounted vertically on a vehicle or a case where the engine is mounted on a vehicle having a relatively flat bonnet line.

The specific structure of each part in the engine of the present invention is not limited to the above embodiment, but can be variously changed.

For example, the interlocking means between the camshafts on the intake valve side and the exhaust valve side is not limited to the gears 36 and 37, but may be a chain or the like. However, as shown in the illustrated embodiment, the gear 3
By using 6, 37, the distance between both camshafts can be reduced as compared with a chain or the like. Therefore, even if the inclination angle of the valve axis of the intake valve becomes small and the angle between the valve axes of the intake and exhaust valves becomes small, no problem occurs.

Further, as the transmission means between the crankshaft and the camshaft, a chain may be used instead of the timing belt 33.

[0053]

As described above, according to the present invention, in the cylinder injection type engine, the intake valve and the intake valve are arranged such that the inclination angle of the valve axis with respect to the cylinder bore axis is smaller in the intake valve than in the exhaust valve.
An exhaust valve is arranged, and a wall surface on an intake port opening side and a wall surface on an exhaust port opening side in a combustion chamber ceiling portion are formed so as to be orthogonal to each of the valve axes, and a cylinder head on a side of the combustion chamber on an intake port opening side. An injector is arranged at a lower portion, and an intake port extending from the combustion chamber toward the upper side of the cylinder head is formed at a portion between the injector and the intake valve shaft. In addition, a space for mounting the injector is secured, and a sufficient space for arranging the intake port is obtained between the portion where the intake valve shaft is arranged and the portion where the injector is arranged. For this reason, the opening area of the intake port is not limited or the intake air flow resistance is not increased, and swirl generation becomes difficult as in the case where the intake port is arranged above the intake valve shaft, and the inlet becomes difficult. Effectively connecting the injector and intake port for in-cylinder injection to the side of the cylinder head on the intake valve side without inconvenience such as the manifold being located above the cylinder head and increasing the overall height of the engine. Can be arranged.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a direct injection engine according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of a combustion chamber of the engine and its vicinity.

FIG. 3 is a plan view of the entire cylinder head of the engine.

FIG. 4 is a schematic front view showing a camshaft drive system of the engine.

FIG. 5 is a schematic front view showing another embodiment of the camshaft drive system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder head 3 Piston 4 Cylinder bore 5 Combustion chamber 6,7 Intake port 8,9 Exhaust port 10 Intake valve 11 Exhaust valve 12 Intake valve side camshaft 13 Exhaust valve side camshaft 15 Injector 16 Ignition plug 23 Swirl control valve 32 Cam pulley 33 Timing belt 36, 37 Gear

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location F02B 23/08 F02B 23/08 CS 23/10 23/10 MD 31/00 31/00 Z 31/02 31/02 G F02F 1/24 F02F 1/24 J 1/42 1/42 F

Claims (6)

[Claims] A combustion chamber is formed between an upper surface of a piston disposed in a cylinder bore and a lower surface of a cylinder head opposed thereto, and an intake port and an exhaust port opening to the combustion chamber are formed in the cylinder head. In an in-cylinder injection type engine in which an intake valve and an exhaust valve for opening and closing the intake port and the exhaust port, an injector for injecting fuel into the combustion chamber, and a spark plug are provided in a cylinder head, the intake valve for the cylinder bore axis is These valves are arranged so that the inclination angle of the valve axis is smaller than the inclination angle of the valve axis of the exhaust valve. The cylinder is formed so as to be orthogonal to the valve axis of the exhaust valve, and at the side of the combustion chamber on the intake port opening side. An in-cylinder injection engine having an injector disposed at a lower portion of a head and an intake port extending from a combustion chamber toward an upper side of a cylinder head at a portion between the injector and an intake valve shaft. . 2. The direct injection engine according to claim 1, wherein a first intake port for swirl generation and a second intake port for tumble generation are provided in parallel as the intake port. 3. The angle of incidence of the downstream end portions of the first and second intake ports with respect to the combustion chamber is the same, and the second intake port is shifted above the first intake port upstream of this portion. The in-cylinder injection engine according to claim 2, wherein an on-off valve for each cylinder is provided upstream of the second intake port. 4. The valve operating mechanism is a DOHC in which both camshafts on an intake valve side and an exhaust valve side are arranged in parallel on a cylinder head, and a camshaft on an exhaust valve side is defined as a height relationship between the two camshafts in the cylinder bore axis direction. Is set lower than the height of the intake valve side camshaft, the exhaust valve side camshaft is driven by a crankshaft via a transmission means, and the intake valve side camshaft is interlocked by the exhaust valve side camshaft. The in-cylinder injection engine according to any one of claims 1 to 3, wherein the in-cylinder injection engine is driven through the engine. 5. The valve mechanism is a DOHC in which both camshafts on an intake valve side and an exhaust valve side are arranged in parallel on a cylinder head, and the camshaft on the exhaust valve side is defined as a height positional relationship between the two camshafts in the cylinder bore axis direction. Is set lower than the height of the intake valve side camshaft, the intake valve side camshaft is driven by a crankshaft via a transmission mechanism, and the exhaust valve side camshaft is interlocked by the intake valve side camshaft. The camshaft drive system is configured to be driven through the hood, and the arrangement of the engine in the engine room below the hood of the vehicle is as follows:
4. The camshaft according to claim 1, wherein the camshaft is laterally extended in the vehicle width direction, and the intake valve side camshaft is located on the vehicle rear side of the exhaust valve side camshaft. The in-cylinder injection engine according to the above description. 6. The direct injection engine according to claim 4, wherein the interlocking means between the two camshafts is constituted by a gear.