JP2010077839A - Intake port structure for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure capable of easily securing an intake air flow rate while sufficiently strengthening swirls inside cylinders 1 in the case of providing a pair of intake ports 2, 3 for each cylinder 1 of an engine in parallel in the direction of a crankshaft. <P>SOLUTION: The first intake port 2 is a so-called tangential port for generating a swirl flow s1 that swirls mainly on the outer peripheral side of the cylinder 1. The second intake port 3 is provided with an expanded part 3c near its opening part 3b expanded to the opposite side from the first intake port 2 for orienting an intake air flow into the cylinder 1 along the inner peripheral side of the outer peripheral side swirl flow s1. The second intake port 3 may be provided with a guide part for guiding intake air flowing relatively at the upper side thereof toward the expanded part 3c, and this may be constituted of a valve guide seat 3d. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a structure in which a pair of intake ports are provided side by side in a crankshaft direction for each cylinder of an engine.

Conventionally, as an intake port structure of this type, as disclosed in, for example, Patent Document 1, the flow of intake air flowing into the cylinder through one of the intake ports is directed in the cylinder circumferential direction. A tangential port, and the other intake port is known as a helical port through which intake air spirally flows into the cylinder from its opening to strengthen the swirl in the cylinder.
JP-A-6-288240

  However, as is generally known, the helical port tends to have a large intake throttle loss, and it is difficult to secure a flow rate in a high rotation range. In addition, the helical port is combined with a tangential port as in the conventional example. In this case, the flow of intake air from these two ports easily interferes with the cylinder, particularly on the outer peripheral side, so there is still room for improvement in terms of strengthening swirl.

  That is, in the conventional example, as schematically shown in FIG. 6, a swirl flow s1 flowing into the cylinder c from the tangential port a and turning mainly on the outer peripheral side, and a spiral shape flowing in from the helical port b And the intake air flow s2 collide with each other between the ports a and b, which is disadvantageous in terms of swirl strengthening, and by colliding in this way, from the helical port b into the cylinder c. However, it is difficult to secure the flow rate.

  The present invention has been made in view of such points, and the object of the present invention is to devise the shape of a pair of intake ports provided for each cylinder of the engine, and to improve intake swirl while sufficiently strengthening the swirl in the cylinder. The structure is to ensure the flow rate easily.

  In order to achieve the above object, the present invention uses one intake port as a so-called tangential port to generate a swirl flow that swirls mainly on the outer peripheral side of the cylinder, and in the vicinity of the opening of the other intake port, A flow directing portion for directing the flow of intake air flowing into the cylinder from there along the inner peripheral side of the swirl flow is provided.

  Specifically, in the first aspect of the present invention, a pair of intake ports for each cylinder are provided in the cylinder head of the engine side by side in the crankshaft direction, and each of the intake ports opens into the cylinder. When viewed along the axis, the engine intake port structure in which a line connecting the centers of the openings extends in the crankshaft direction is an object.

  Then, the first intake port, which is one of the paired intake ports, is directed to the opposite side to the second intake port, which is the other intake port, in the vicinity of the opening, and the intake air flowing into the cylinder In the vicinity of the opening of the second intake port, the flow of the intake air flowing into the cylinder from the opening toward the first intake port is provided near the opening of the second intake port. A flow directing unit for directing is provided. Then, the flow directing portion is sandwiched between two imaginary lines respectively viewed from the center of the opening of the second intake port to the center of the cylinder and the center of the opening of the first intake port as viewed along the cylinder axis. The flow of the intake air is directed so as to go to the triangular region, and the flow velocity is made lower than the intake air flow from the first intake port.

  With the above-described configuration, in the intake stroke of a cylinder, the cylinder mainly turns on the outer peripheral side by the flow of intake air directed into the cylinder circumferential direction while flowing into the cylinder from the first intake port, which is a so-called tangential port. While the swirl flow is generated, the flow of the intake air flowing into the cylinder from the second intake port is directed to the first intake port side from the cylinder axis by the flow directing portion provided in the vicinity of the opening, This flow does not collide with the swirl flow.

  Further, the flow of the intake air from the second intake port is directed toward the cylinder axis side from the center of the opening of the first intake port, that is, the inner peripheral side of the cylinder from the flow of the intake air from the first intake port. Furthermore, since the flow velocity is relatively low, it flows along the inner peripheral side without much interference with the swirl flow on the outer peripheral side.

  That is, swirl flows are generated on the inner and outer peripheries of the cylinder by the flow of intake air from the first and second intake ports, respectively, and their interference is suppressed and the swirl in the cylinder is sufficiently strengthened. be able to. Further, it is preferable not to use the helical port in order to secure the intake flow rate, and it is easy to secure the intake flow rate by suppressing the interference of the flows from the two intake ports as described above.

  More specifically, it is preferable that the flow directing portion is provided with an extended portion that is extended on the side opposite to the first intake port in the vicinity of the opening of the second intake port (Claim 2). By doing so, it is possible to direct the intake air flowing along the inner surface of the expansion portion without restricting the intake air toward the first intake port side, and to appropriately reduce the flow velocity. Thus, even if the expansion portion is provided, intake throttle loss does not increase as in the case of the helical port.

  In that case, it is more preferable to provide a guide portion for guiding the flow of intake air in the second intake port so as to face the expansion portion. For example, the guide portion can be constituted by a valve guide seat protruding into the second intake port. Further, if the second intake port is curved toward the intake upstream side of the valve guide seat so as to be away from the first intake port, the flow of intake air in the second intake port is naturally expanded. Head to the club.

  On the other hand, for the first intake port, it is preferable to provide a curved portion that curves so as to approach the second intake port on the intake upstream side of the opening facing the cylinder. In this way, the first intake port bends relatively gently from the curved portion to the opening, and the flow of intake can be smoothly directed in the cylinder circumferential direction. It is easy to secure the intake flow rate.

  However, when applied to a diesel engine, a glow plug is generally disposed between the first and second intake ports, and a curved portion that approaches the second intake port is provided as described above. And this curved part will interfere with the accommodation hole of a glow plug.

  Therefore, in this case, the curved portion is formed so as to be closest to the second intake port on the intake downstream side of the portion where the port center line and the glow plug shaft center intersect when viewed in the crankshaft direction. ). That is, since the glow plug is generally arranged so as to rise from the ceiling of the combustion chamber at a steep slope compared to the intake port, if the curved portion is provided on the downstream side of the intake as described above, it interferes with the plug accommodation hole. This is because the part is a part relatively lower than the first intake port, and it is easy to secure the intake flow rate even if the part is shaped to squeeze that part in order to avoid interference.

  As described above, according to the intake port structure of the engine according to the present invention, one intake port for each cylinder is used as a so-called tangential port, and a swirl flow mainly turning around the outer periphery of the cylinder is generated, and the other A flow directing portion is provided in the vicinity of the opening of the intake port so that the flow of intake air flowing into the cylinder from there is directed along the inner peripheral side of the swirl flow, and the flow velocity is appropriately reduced. Therefore, the swirl flow can be generated on the inner and outer circumferences of the cylinders while suppressing the interference of the flow, and the swirl can be sufficiently strengthened.

  As a result, the interference of the flow from the two intake ports can be suppressed, and since the helical port is not used, it is easy to ensure the intake air flow rate even in the high engine speed range. If an expansion portion is provided in the vicinity of the opening of the second intake port as the flow directing portion, the flow can be directed as intended without greatly increasing the throttle loss of the intake air.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the following description of preferable embodiment is only an illustration essentially, and is not intending restrict | limiting this invention, its application thing, or its use.

  FIG. 1 schematically shows an intake port structure of an engine according to an embodiment of the present invention. When viewed along the axis C of the cylinder 1 as shown in the figure, the first and second pairs forming each cylinder 1 are paired. 2, two intake ports 2 and 3 are provided side by side in the crankshaft direction (left-right direction in the figure), and extend so as to be substantially orthogonal to the crankshaft direction. Although not shown, the intake upstream ends 2a and 3a of the intake ports 2 and 3 open to one side of the cylinder head and communicate with an intake passage in the intake manifold. The intake downstream ends 2 b and 3 b are opened facing the combustion chamber in the cylinder 1.

  Although not shown in FIG. 1, an intake valve 4 comprising a poppet valve (not shown in FIGS. 3 and 4) is provided in the openings 2b and 3b at the intake downstream ends of the first and second intake ports 2 and 3. Port openings 2b and 3b that are opened and closed by the umbrella portion of the intake valve 4 are arranged so that the line segment L connecting the centers thereof is parallel to the crankshaft center. They are lined up in the direction of the crankshaft. In this embodiment, the intake valves 4 that open and close the first and second intake ports 2 and 3 are the same, but separate intake valves having different umbrella diameters may be used, for example.

  Although not shown, the engine of this embodiment is, for example, an in-cylinder direct injection type diesel engine mounted on an automobile. Between the first and second intake ports 2 and 3, a cold start or the like is performed. A glow plug 5 that is energized is disposed with its tip (upper end in the figure) facing the cylinder 1. As shown in the figure, when viewed along the cylinder axis C, there is almost no gap between the first intake port 2 and the glow plug 5, but as will be described later, the intake downstream side of the first intake port 2 A partition wall having a required thickness is formed between the glow plug 5 and the receiving hole.

  In the drawing, an exhaust port is opened above the first and second intake ports 2 and 3 that are opened side by side on the left and right sides, and the fuel faces the combustion chamber ceiling along the cylinder axis C. Although the injection valve is provided, none of them shows the characteristics of the present invention, and therefore illustration is omitted.

  The feature of the present invention resides in the shape of the first and second intake ports 2 and 3 described above. First, the first intake port 2 is directed to the opposite side of the second intake port 3 in the vicinity of the opening 2b as shown in the figure, and the intake air flowing into the cylinder 1 is directed in the cylinder circumferential direction. This is a so-called tangential port. The swirl flow s1 (hereinafter referred to as the outer swirl flow hereinafter) swirling mainly on the outer peripheral side in the cylinder 1 as indicated by the white arrow in the drawing by the intake air flowing into the cylinder 1 while being directed in the cylinder circumferential direction. Is generated).

  In the example shown in the figure, the first intake port 2 has a curved portion 2c that curves so as to approach the second intake port 3 over a predetermined range from the opening 2b to the upstream side of the intake, and has an inverted S-shape as a whole. It has become. From the curved portion 2c to the opening 2b, the first intake port 2 is curved relatively gently with a substantially constant radius of curvature R, whereby the intake air flows into the cylinder 1 while being directed smoothly in the cylinder circumferential direction. Therefore, it is easy to ensure the flow rate even in the high engine speed range.

  Further, in the example shown in the figure, the portion of the curved portion 2c that is closest to the second intake port 3 is located relatively on the intake downstream side (upper side in the drawing) of the first intake port 2, thereby the glow plug 5 It is easy to secure the flow rate of the intake air while avoiding interference. That is, as shown in FIG. 2, when viewed in the crankshaft direction, the glow plug 5 is disposed so as to rise more steeply than the first intake port 2, and its tip side is on the intake downstream side of the first intake port 2. While overlapping the lower half, the base end side overlaps the upper half on the intake upstream side.

  Therefore, if the portion closest to the second intake port 3 in the curved portion 2c of the first intake port 2 is on the intake upstream side of the first intake port 2, the interference with the glow plug 5 is avoided. However, the upper half of the first intake port 2 must have a shape that is curved, but the flow of intake air tends to be more biased toward the upper half than the lower half. If the half portion is shaped like a half, the adverse effect of securing the intake air flow rate will increase.

  Therefore, in this embodiment, as viewed in the crankshaft direction as shown in FIG. 2, the first intake air is located downstream of the intersection X between the axial center of the first intake port 2 and the axial center of the glow plug 5. The curved portion 2 c of the port 2 is made closest to the second intake port 3. In this way, in order to avoid interference with the glow plug 5, even if the shape of the lower half of the curved portion 2c is raised, the intake flow rate can be ensured as compared to the shape of the upper half. The adverse effect on the is small.

  Next, the second intake port 3 will be described. As apparent from FIG. 1, the second intake port 3 is bent toward the cylinder axis C in the vicinity of the opening 3b, and the opening 3b is shown in FIGS. In the vicinity of the first intake port 2 has an expansion portion 3c that is expanded on the opposite side in the cylinder circumferential direction, whereby the flow rate of the intake air flowing into the cylinder 1 is lowered while being moderately reduced. Is directed toward the first intake port 2.

  More specifically, as shown in FIG. 5, the second intake port 3 is bent to the left side in the vicinity of the opening 3b when viewed along the cylinder axis C, and an expanded portion 3c is formed on the right side thereof. As a whole, the port width is increased. As apparent from the cross section of FIG. 4, the port width is increased vertically on the intake downstream side of the second intake port 3, while the valve guide seat 3 d that holds the valve guide 6 projects into the port from above. ing.

  Here, since the second intake port 3 is directed to the cylinder axis C in the vicinity of the opening as described above, when viewed along the cylinder axis C as shown in FIG. Although it seems that it is shifted to the opposite side (left side in the figure) of the expanded portion 3c in the vicinity of the opening 3b where the port width is widened, the second intake port 3 itself is the valve guide when viewed excluding the expanded portion 3c. It can be said that the air intake upstream side of the seat 3d is curved toward the upstream side away from the first intake port 2 (to the right in the drawing).

  Therefore, the intake air flowing relatively above the second intake port 3 flows substantially straight along the port center line on the intake upstream side of the second intake port 3 as shown by the solid line arrow in FIG. Then, it naturally goes toward the expansion portion 3c so as to be guided by the valve guide seat 3d. The flow of the intake air thus guided to the expansion portion 3c is greatly changed along the inner surface of the expansion portion 3c and directed toward the first intake port 2 as shown in the drawing, and the flow velocity is reduced.

  On the other hand, the intake air flowing relatively below the second intake port 3 flows into the cylinder 1 from the opening 3b substantially along the center line of the port as indicated by the dashed arrow in the drawing, as described above. Combined with the flow directed to the first intake port 2 side, as a whole, two lines respectively extending from the center of the second intake port opening 3c to the cylinder axis C and the center of the first intake port opening 2c. It goes to a triangular region T (indicated by a virtual line in the figure) sandwiched between minutes.

  Thus, the flow of intake air from the second intake port 3 is directed closer to the first intake port 2 than the cylinder axis C, and does not collide with the outer circumferential swirl flow s1 described above. Further, since the flow is closer to the cylinder axis C than the center of the opening of the first intake port 2, and the flow velocity is relatively low, the outer swirl flow s1 as shown by the white arrow in FIG. And swivel on the inner circumference side (inner circumference side swirl flow s2).

  Therefore, according to the intake port structure of the engine according to this embodiment, the cylinder 1 is caused by the flow of intake air directed into the cylinder circumferential direction while flowing into the cylinder 1 from the first intake port 2 which is a so-called tangential port. A strong swirl flow s1 is generated on the outer peripheral side of the cylinder, and a swirl flow s2 is generated on the inner peripheral side by the flow of intake air from the second intake port 3, and the interference of these flows is suppressed and the cylinder is suppressed. The swirl within 1 can be sufficiently strengthened.

  In the second intake port 3, the expansion portion 3c provided in the vicinity of the opening 3b directs the flow in the intended direction without increasing the intake throttle loss as in the case of a helical port, for example. Therefore, it is easy to ensure a sufficient intake flow rate even in the high engine speed range. As described above, it is also preferable for ensuring the intake flow rate that the intake air flows from the first and second intake ports 3 and 4 do not interfere so much.

  In addition, the structure of this invention is not limited to the said embodiment, Other various structures are included. That is, in the above embodiment, the curved portion 2c is provided on the intake downstream side of the first intake port 2, but if the glow plug 5 is disposed obliquely closer to the second intake port 3, a larger curvature radius is provided. The curved portion 2 c can be provided over the intake upstream side of the first intake port 2. However, for that purpose, the accommodation hole of the glow plug 5 must be drilled obliquely from the side surface of the cylinder head, which may increase the cost.

  Although it is possible not to provide the curved portion 2c in the first intake port 2, in this case, the inflow radius of the intake air from the first intake port 2 into the cylinder 1 is reduced, and a strong swirl is formed on the outer peripheral side. This is disadvantageous from the viewpoint of generating a flow, and also increases the possibility of interference with the inner swirl flow.

  On the other hand, for the second intake port 3, in the above-described embodiment, the expansion portion 3c is provided as a flow directing portion for setting the direction of intake air into the cylinder 1, and a valve guide is provided as a guide portion for guiding the intake toward the extension portion 3c. Although the seat 3d is used, it is not limited to such a structure.

  Furthermore, it goes without saying that the intake port structure according to the present invention can be applied not only to a diesel engine but also to a gasoline engine.

It is explanatory drawing of the intake port structure which concerns on embodiment of this invention. It is explanatory drawing which shows the mutual positional relationship of a 1st intake port and a glow plug. FIG. 3 is a cross-sectional view of a second intake port taken along line III-III in FIG. 1. FIG. 4 is a cross-sectional view of a second intake port taken along IV-IV in FIG. 1. It is explanatory drawing which shows the flow of the intake air in a 2nd intake port. FIG. 10 is a view corresponding to FIG. 1 according to a conventional example.

Explanation of symbols

1 Cylinder 2 First Intake Port 2b Opening Portion (Opening Portion) of Inlet Downstream End
2c Curved portion 3 Second intake port 3b Opening portion (opening portion) at intake downstream end
3c Extension part (flow directing part)
3d Valve guide seat (guide section, flow directing section)
5 Glow plug 6 Valve guide X Intersection of port center line and glow plug axis viewed in the crankshaft direction

Claims (6)

A pair of intake ports for each cylinder are provided in the cylinder head of the engine side by side in the crankshaft direction, and each of the intake ports opens into the cylinder when viewed along the cylinder axis. An engine intake port structure in which a line connecting the centers of the parts extends in the crankshaft direction,
The first intake port that is one of the paired intake ports is directed to the opposite side of the second intake port that is the other intake port in the vicinity of the opening, and the flow of intake air flowing into the cylinder is changed to the cylinder A tangential port oriented in the circumferential direction,
In the vicinity of the opening of the second intake port, a flow directing portion is provided for directing the flow of intake air flowing into the cylinder from the opening toward the first intake port,
When viewed along the cylinder axis, the flow directing portion is sandwiched between two imaginary lines respectively directed from the center of the opening of the second intake port to the center of the cylinder and the center of the opening of the first intake port. An intake port structure for an engine characterized in that the flow of the intake air is directed so as to go to a triangular region, and the flow velocity thereof is made lower than the intake air flow from the first intake port. .   2. The intake port structure according to claim 1, wherein the flow directing portion has an extended portion that is extended to the opposite side of the first intake port in the vicinity of the opening of the second intake port.   The intake port structure according to claim 2, wherein the flow directing portion has a guide portion that guides the flow of intake air in the second intake port toward the expansion portion. The guide portion is constituted by a valve guide seat protruding into the second intake port,
The intake port structure according to claim 3, wherein the second intake port is curved toward the intake upstream side from the valve guide seat so as to be separated from the first intake port.   The intake port structure according to any one of claims 1 to 4, wherein the first intake port has a curved portion that curves so as to approach the second intake port on the intake upstream side of the opening facing the cylinder. The engine is a diesel engine, a glow plug is disposed between the first and second intake ports,
The curved portion of the first intake port is formed so as to be closest to the second intake port on the intake downstream side of the portion where the port center line and the axis of the glow plug intersect when viewed in the crankshaft direction. The intake port structure according to claim 5.

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