JP4879681B2 - Stratified combustion internal combustion engine - Google Patents

Description

  The present invention relates to a main intake port that supplies a lean air-fuel mixture to a peripheral region in a combustion chamber defined between a cylinder head and a piston so as to give a swirl in a certain direction thereto, A sub-intake port that supplies a rich air-fuel mixture to the central region where the electrode of the spark plug faces, and a main intake valve and a sub-intake valve that open and close each outlet of the main intake port and the sub intake port that open to the combustion chamber The present invention relates to an improvement of a stratified combustion internal combustion engine provided in a head.

Such a stratified combustion internal combustion engine is already known as disclosed in Patent Document 1.
Japanese Utility Model Publication No. 63-13382

  In such a stratified combustion internal combustion engine, in general, the outlet of the main intake port that opens into the combustion chamber is formed as large as possible in order to increase the intake efficiency. Therefore, the outlet is arranged on the outer peripheral side of the combustion chamber. Even so, a part of the portion protrudes toward the central region of the combustion chamber. For this reason, when supplying the lean air-fuel mixture from the main intake port to the combustion chamber, a part of the lean air-fuel mixture flows from the outlet that protrudes toward the central region to the central region and is supplied to the central region. In many cases, the rich air-fuel mixture is diluted, and the ignitability of the rich air-fuel mixture is impaired.

  The present invention has been made in view of such circumstances, and when supplying a lean air-fuel mixture from the main intake port to the combustion chamber, the lean air-fuel mixture is prevented from flowing into the central region, It is an object of the present invention to provide a stratified combustion internal combustion engine capable of avoiding dilution of the rich mixture supplied to the region and stabilizing the ignitability of the rich mixture.

In order to achieve the above object, the present invention provides a lean air-fuel mixture in the outer peripheral region of the combustion chamber defined between the cylinder head and the piston, and the central portion of the combustion chamber facing the spark plug electrode. In a stratified combustion internal combustion engine in which a rich air-fuel mixture is maintained in a region until ignition by a spark plug, the top surface of the piston facing the combustion chamber is partitioned between the outer peripheral region and the central region. A projecting annular convex wall is integrally formed, a lean air-fuel mixture is supplied to the outer peripheral region, and a rich air-fuel mixture is supplied to the central region to supply the outer peripheral region with a swirl in a certain direction. A sub-intake port for supplying a swirl of the lean mixture in the same direction as the swirl, a main intake valve and a sub-intake valve for opening and closing the main intake port and the sub-intake port, respectively, Suck A valve operating mechanism for opening and closing the valve and auxiliary intake valves, disposed adjacent to the sub-intake port provided with an exhaust port opening into the combustion chamber in the cylinder head, and the sub-intake port, a main intake port, from the combustion chamber center The spark plug offset radially outward and the exhaust port are arranged in this order sequentially from the upstream side to the downstream side in the flow direction of the swirls and around the center of the combustion chamber, and the outlet of the main intake port On the inner peripheral surface of the end portion on the side of the auxiliary intake port , a collar portion protruding from the main intake port to cover the portion near the center region of the umbrella portion of the main intake valve is formed on the cylinder head. In the ceiling surface of the combustion chamber, a concave groove that communicates between the electrode of the spark plug and the outlet of the auxiliary intake port is provided so as to face the central region inside the annular convex wall. First feature.

  According to the present invention, in addition to the first feature, the outlet of the main intake port is constituted by an annular main intake valve seat member that is embedded in the ceiling surface of the combustion chamber and on which the main intake valve is seated. A second feature is that the flange portion is formed integrally with the valve seat member.

  According to the first aspect of the present invention, in the stratified combustion internal combustion engine, when the lean air-fuel mixture exits the outlet of the intake port, the lean air-fuel mixture causes the portion of the main intake valve near the central region to be the main intake air. The flange that covers the inside of the port ensures that the flow to the central region side is prevented, and the lean mixture can generate swirl in the outer peripheral region as a whole, and therefore the center of the lean mixture Unnecessary scattering to the partial region can be prevented, so that dilution of the rich mixture supplied to the central region can be avoided and the ignitability of the rich mixture can be stabilized. And since the said collar part does not become a protrusion part to a combustion chamber, it does not inhibit the flow of the said swirl at all.

In particular, the outer peripheral region where the swirl of the lean air-fuel mixture is generated and the central region where the swirl of the rich air-fuel mixture is supplied are partitioned by an annular convex wall formed on the top surface of the piston. Is formed in a cavity deeper than the outer peripheral region, so that the mixture of the lean mixture and the rich mixture can be prevented by the annular convex wall, and the rich mixture can be held by the cavity. Dilution due to the lean mixture can be effectively avoided , and the swirl of the lean mixture and the swirl of the rich mixture also take the same direction, preventing mutual interference between the swirls and mixing the two mixtures. It is effective in avoiding. As a result, the rich air-fuel mixture in the center region can be ignited accurately when the spark plug is ignited, and the lean air-fuel mixture can be reliably burned by the flame, and stable stratified combustion can be performed. Can be improved. In addition, a concave groove communicating between the electrode of the spark plug and the outlet of the auxiliary intake port is provided on the ceiling surface of the combustion chamber of the cylinder head so as to face the central region inside the annular convex wall. This concave groove, in cooperation with the cavity inside the annular convex wall of the piston, constitutes a thick and compact reservoir for the rich mixture, and prevents diffusion of the rich mixture to the outer peripheral region. In addition, the concave groove is immovable unlike the above-described cavity, so that the rich air-fuel mixture retains better and the ignitability of the rich air-fuel mixture can be further enhanced.

  According to the second feature of the present invention, the flange portion can be integrally formed with the main intake valve seat member and is easy to manufacture.

  Embodiments of the present invention will be described below on the basis of preferred embodiments of the present invention shown in the accompanying drawings.

  1 is a plan view of a stratified combustion internal combustion engine according to the present invention when the main intake valve is opened, FIG. 2 is a cross-sectional view taken along the line 2-2 of FIG. 1, and FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 3, FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 1, and FIG. 6 is an open / close characteristic diagram of main and auxiliary intake valves and exhaust valves. is there.

  First, in FIG. 1, FIG. 2 and FIG. 5, an engine body 1 of an internal combustion engine includes a cylinder block 2 having a cylinder bore 2a and a cylinder head 4 joined to the upper end surface of the cylinder block 2 via a gasket 3. A combustion chamber 6 is defined between the opposed surfaces of the piston 5 and the cylinder head 4 that are configured to move up and down the cylinder bore 2a.

  An annular main intake valve seat member 7, auxiliary intake valve seat member 8 and exhaust valve seat member 9 are attached to the cylinder head 4 so as to be embedded in the ceiling surface of the combustion chamber 6, and an ignition plug 10 is attached to the cylinder head 4. The electrode is screwed so as to face the combustion chamber 6. The main intake valve seat member 7 has a larger diameter than the exhaust valve seat member 9, and the auxiliary intake valve seat member 8 has a smaller diameter than the exhaust valve seat member 9.

  The main intake valve seat member 7 is disposed on the outermost peripheral portion of the combustion chamber 6, and the auxiliary intake valve seat member 8 is adjacent to one side of the main intake valve seat member 7 and from the main intake valve seat member 7 to the combustion chamber 6. The exhaust valve seat member 9 is disposed adjacent to one side of the auxiliary intake valve seat member 8 on the side opposite to the main intake valve seat member 7, and the electrode of the spark plug 10 serves as the main intake valve. The seat member 7 and the exhaust valve seat member 9 are disposed as close as possible to the center of the combustion chamber 6.

  The cylinder head 4 is provided with a main intake port 11 connected to the main intake valve seat member 7, a sub intake port 12 connected to the sub intake valve seat member 8, and an exhaust port 13 connected to the exhaust valve seat member 9. 12 and the exhaust port 13 are arranged adjacent to each other. Thus, the main intake valve seat member 7 hits the outlet opening to the combustion chamber 6 of the main intake port 11, and the auxiliary intake valve seat member 8 hits the outlet opening to the combustion chamber 6 of the auxiliary intake port 12. The main intake port 11 is connected to a lean mixture supply device 14 for supplying a mixture having an air-fuel ratio larger than the stoichiometric air-fuel ratio, that is, a lean mixture, and the auxiliary intake port 12 has an air-fuel ratio of the stoichiometric air-fuel ratio. A rich mixture supply device 15 for supplying a smaller mixture, that is, a rich mixture is connected.

Thus, as shown in FIGS. 1 and 3, the auxiliary intake port 12, the main intake port 11, the electrode of the spark plug 10 offset radially outward from the center of the combustion chamber 6, and the exhaust port 13 Are arranged in this order sequentially from the upstream side to the downstream side in the flow direction of swirls S1 and S2, which will be described later, and around the center of the combustion chamber 6.

  On the ceiling surface of the combustion chamber 6, a concave groove 22 (see FIG. 5) that communicates between the outlet 8 of the auxiliary intake port 12 and the electrode of the spark plug 10 is provided.

  The cylinder head 4 is separated from or seated on the main intake valve seat member 7, the auxiliary intake valve seat member 8 and the exhaust valve seat member 9, respectively, so that the main intake port 11, the auxiliary intake port 12 and the exhaust port 13 are seated. A main intake valve 18, a sub intake valve 19 and an exhaust valve 20 that open and close the engine, and a valve mechanism 21 that individually opens and closes the main intake valve 18, the sub intake valve 19 and the exhaust valve 20 are provided.

  An annular convex wall 16 that partitions the combustion chamber 6 into an annular outer peripheral region 23 and a central region 24 surrounded by the outer peripheral region 23 is integrally formed on the top surface of the piston 5 facing the combustion chamber 6. At the same time, the inside of the annular convex wall 16 is formed in a cavity 17 deeper than the outer peripheral region 23. Thus, most of the main intake valve seat member 7 is disposed in the outer peripheral region 23, and the entire sub intake valve seat member 8 is disposed in the central region 24.

  Moreover, the main intake port 11 is formed in a helical shape so as to reach the main intake valve seat member 7 while turning from the outside in the radial direction of the combustion chamber 6, and the rich mixing supplied from the main intake port 11 to the combustion chamber 6. The first swirl S1 (see FIGS. 1 and 2) in a certain direction is given to the outer peripheral region 23. Further, on the inner peripheral surface of the main intake valve seat member 7, a portion that protrudes toward the central region 24 side of the umbrella portion 18 a of the main intake valve 18 is covered with the main intake port 11 and close to the valve flange portion 18 b. An arcuate collar portion 27 is integrally formed.

  On the other hand, the auxiliary intake port 12 is formed so as to be directed in the tangential direction of the central region 24 in the direction of the first swirl S1. Thereby, the second swirl S2 (see FIGS. 3 and 4) in the same direction as the first swirl S1 is given to the rich air-fuel mixture supplied from the auxiliary intake port 12 to the combustion chamber 6 in the central region 24. Yes.

  The valve mechanism 21 opens and closes the main intake valve 18, the sub intake valve 19 and the exhaust valve 20 with the characteristics shown in FIG. In particular, the main intake valve 18 is controlled by the valve mechanism 21 so that it starts to open at substantially the start time of the intake stroke and closes at the almost end time of the intake stroke, whereas the sub intake valve 19 has the intake stroke of the intake stroke. It is controlled by the valve mechanism 21 so that it opens in the second half and closes in the first half of the compression stroke after the main intake valve 18 is closed. Thus, the closing of the main intake valve 18 is advanced and the closing of the auxiliary intake valve 19 is delayed in order to draw the rich mixture into the cylinder bore 2a due to the negative pressure remaining in the cylinder bore 2a in the first half of the compression stroke.

  Further, the opening lift amount of the auxiliary intake valve 19 is sufficiently smaller than that of the main intake valve 18, and is set to approximately ½ of that in the illustrated example, thereby reducing the amount of the rich mixture to be drawn into the cylinder bore 2a. It is adjusted to be sufficiently smaller than the amount of the lean mixture.

  Next, the operation of this embodiment will be described with reference to FIG.

  When the intake stroke of the engine starts, as shown in FIGS. 1 and 2, first, the main intake valve 18 is opened, so that the lean air-fuel mixture is introduced into the combustion chamber 6 from the main intake port 11. At this time, the lean air-fuel mixture is guided by the helical main intake port 11 and generates a first swirl S1 in a certain direction in the outer peripheral region of the combustion chamber 6. In particular, when the lean air-fuel mixture exits from the outlet 7 of the main intake port 11, the lean air-fuel mixture has a portion that protrudes toward the central region 24 side of the umbrella portion 18 a of the main intake valve 18 within the main intake port 11. Since the covering arc-shaped flange portion 27 reliably prevents the flow toward the center region 24, the lean mixture generates the first swirl S1 in the outer peripheral region 23 as a whole, and the lean mixture Unnecessary scattering to the center region 24 can be prevented. And since the said collar part 27 does not become a protrusion part to the combustion chamber 6, it does not inhibit the flow of 1st swirl S1 at all.

  Further, the flange portion 27 is formed integrally with the annular main intake valve seat member 7 which is embedded in the ceiling surface of the combustion chamber 6 and constitutes the outlet 7. It is possible and easy to manufacture.

  The auxiliary intake valve 19 starts to open in the latter half of the intake stroke, and the opening of the auxiliary intake valve 19 continues even when the main intake valve 18 is closed at the end of the intake stroke, and closes in the first half of the compression stroke. As a result, the rich air-fuel mixture is supplied from the auxiliary intake port 12 to the central region 24 of the combustion chamber 6 as shown in FIGS. 3 and 4. As described above, the auxiliary intake port 12 is formed so as to be directed in the tangential direction of the central region 24 in the direction of the first swirl S1, so that the rich air-fuel mixture in the central region 24 is the first swirl S1. The second swirl S2 is generated in the same direction. As described above, the second swirl S2 of the rich mixture is generated later than the first swirl S1 of the lean mixture, so that the mixture of the lean mixture and the rich mixture can be avoided as much as possible.

  Moreover, in the combustion chamber 6, the outer peripheral region 23 and the central region 24 surrounded by the outer peripheral region 23 are partitioned by the annular convex wall 16 of the piston 5. Since the deeper cavity 17 is formed, the annular convex wall 16 prevents the mixture of the lean mixture and the rich mixture, and the cavity 17 holds the rich mixture. It is also effective to prevent the first swirl S1 of the lean mixture and the second swirl S2 of the rich mixture from taking the same direction, thereby preventing mutual interference between the swirls and avoiding the mixture of the two mixtures.

  Thus, the rich air-fuel mixture in the central region 24 reaches the end of the compression stroke without being diluted by the lean air-fuel mixture in the outer peripheral region 23, so that it can be ignited accurately when the spark plug 10 is ignited. As a result, the lean air-fuel mixture can be reliably combusted by the generated flame, stable stratified combustion can be performed, and low fuel consumption can be improved.

  In addition, the concave groove 22 provided on the ceiling surface of the combustion chamber 6 and communicating between the electrode of the spark plug 10 and the outlet 8 of the auxiliary intake port 12 cooperates with the deep cavity 17 to provide a thick compact. This constitutes a storage portion for a rich mixture, which contributes to prevention of diffusion of the rich mixture to the outer peripheral region 23. In particular, the concave groove 22 is immovable unlike the cavity 17, so that the retention of the rich mixture is good and the ignitability of the rich mixture can be enhanced.

  Further, since the auxiliary intake port 12 is disposed adjacent to the exhaust port 13, vaporization of the rich air-fuel mixture passing through the auxiliary intake port 12 is promoted by heating with exhaust heat, and the ignitability can be further enhanced.

  In addition, this invention is not limited to the said Example, A various design change is possible in the range which does not deviate from the summary.

The top view shown in the open state of the main intake valve of the stratified combustion internal combustion engine of this invention. FIG. 2 is a sectional view taken along line 2-2 in FIG. 1. The corresponding figure with FIG. 1 which shows the open state of a sub intake valve. FIG. 4 is a sectional view taken along line 4-4 of FIG. FIG. 5 is a sectional view taken along line 5-5 in FIG. Opening / closing characteristics diagram of main and auxiliary intake valves and exhaust valves.

4 ... Cylinder head 5 ... Piston 6 ... Combustion chamber 7 ... Main intake port outlet (Main intake valve seat member)
8 ... Sub-intake port outlet (sub-intake valve seat member)
10... Spark plug 11... Main intake port 12... Sub intake port 16... Annular convex wall 18. · Sub-intake valve 21 ··· Valve mechanism 22 ··· Groove 23 · · · Outer peripheral region 24 · · · Central region 27 ··· Saddle S1 · · · Swirl S2 by ... Swirl by rich mixture

Claims (2)

A lean air-fuel mixture is applied to the outer peripheral region (23) in the combustion chamber (6) defined between the cylinder head (2) and the piston (5), and the ignition plug (10 In the stratified combustion internal combustion engine in which the rich air-fuel mixture is held in the central region (24) where the electrode of) faces before ignition by the spark plug (10),
On the top surface of the piston (5) facing the combustion chamber (6), an annular convex wall (16) protruding so as to partition the outer peripheral region (23) and the central region (24) is integrally formed. ,
A main intake port (11) for supplying a lean air-fuel mixture to the outer peripheral region (23) and a swirl (S1) in a certain direction to the outer peripheral region (23); and the central region (24) A sub-intake port (12) for supplying a rich mixture to the swirl (S2) in the same direction as the swirl (S1) of the lean mixture, and the main intake port (11) and the sub-intake port A main intake valve (18) and a sub intake valve (19) for opening and closing each of (12), a valve operating mechanism (21) for driving the main intake valve (18) and the sub intake valve (19) to open and close , An exhaust port (13) disposed adjacent to the intake port (12) and opened to the combustion chamber (6 ) is provided in the cylinder head (2).
The auxiliary intake port (12), the main intake port (11), the spark plug (10) offset radially outward from the center of the combustion chamber (6), and the exhaust port (13) in this order. The swirls (S1, S2) are arranged sequentially from the upstream side to the downstream side in the flow direction and around the center of the combustion chamber (6),
On the inner peripheral surface of the outlet (7) of the main intake port (11) on the side of the auxiliary intake port (12) , there is a central region (24) of the umbrella portion (18a) of the main intake valve (18). A protrusion (27) is provided so as to cover the close portion within the main intake port (11),
A concave groove (communication between the electrode of the spark plug (10) and the outlet (8) of the auxiliary intake port (12) is formed in the ceiling surface of the combustion chamber (6) formed in the cylinder head (2). A stratified combustion internal combustion engine characterized in that 22) is provided so as to face the central region (24) inside the annular convex wall (16). The stratified combustion internal combustion engine according to claim 1,
The outlet of the main intake port (11) is constituted by an annular main intake valve seat member (7) embedded in the ceiling surface of the combustion chamber (6) and seated by the main intake valve (18). A stratified combustion internal combustion engine characterized in that the flange (27) is formed integrally with a seat member (7).

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