JP2011241742A - Engine intake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine intake device capable of optimizing intake air flow balance with simple structure.SOLUTION: The engine intake device includes: an intake port 40 that is disposed at a slant with respect to a cylinder 10 into which a piston 20 is inserted and which includes a combustion chamber, and that introduces combustion air into the combustion chamber and that has a cylinder-side area branched into a plurality of flow passages; an intake valve 50 which is driven by a valve train mechanism and opens/closes the combustion chamber-side end of the intake port; a partition wall 41 for dividing a flow passage cross-section upstream from the branching place of the intake port into the cylinder side and the valve train mechanism side; and a flow passage control valve 42 which is provided in the upstream side of the partition wall in the intake port and opens/closes the cylinder-side area of the flow passage cross-section of the intake port according to a running state. A downstream-side end position of the partition wall is changed in the width direction of the intake port.

Description

  The present invention relates to an intake device for an engine that generates a tumble by using a partition wall that partitions a flow passage section of an intake port and a control valve that changes the flow passage, and particularly relates to an intake air flow balance that is optimized by a simple configuration.

For example, in a reciprocating internal combustion engine such as an automobile gasoline engine, it is required to promote mixing of air and fuel to obtain a more homogeneous air-fuel mixture. Further, in such a reciprocating internal combustion engine, it is required to improve the thermal capacity by improving the isovolume, and to improve the flame propagation speed in order to suppress knocking due to self-ignition of the unburned part. Yes.
In order to promote the mixing of fuel and intake air and improve the flame propagation speed, it is known that it is effective to form an air flow such as swirl and tumble in the combustion chamber. The swirl is a swirl flow (lateral vortex) around the cylinder axis, and the tumble is a swirl flow (vertical vortex) around an axis substantially parallel to the rotation axis of the engine.

As a conventional technique for enhancing the tumble flow, for example, in Patent Document 1, an intake port of an engine provided with a partition that divides the intake port into two parts, upper and lower, and a control valve that closes the flow path below the partition (cylinder block side). An apparatus is described.
According to such a configuration, when the engine is under a low load, the lower part of the intake port is closed by the control valve, and the intake part flows at a high speed through the upper part of the intake port, so that a tumble flow can be generated inside the cylinder. .

  Further, in Patent Document 2, the downstream end portion of the partition wall extends to the vicinity of the valve stem, and the fuel adhering to the partition wall flows smoothly from the triangular portion provided here, so that the deterioration of combustion due to intermittent inflow of fuel It is described to prevent.

Japanese Unexamined Patent Publication No. 7-119472 JP-A-6-159203

As described above, in the engine intake device that generates the tumble, it is important to optimize the balance of the flow strength in the crankshaft axial direction.
For example, in the case of an engine having two intake valves per cylinder, it is not preferable that the balance between the airflow passing through the inside of the two intake valves and the airflow passing through the outside is biased.
However, in the technologies described in Patent Documents 1 and 2 described above, such a balance of flow strength in the axial direction of the crankshaft is not taken into consideration. Further, in the configuration of Patent Document 2, an intake port having a plurality of partition walls is branched. Therefore, the structure and the manufacturing method become complicated.
An object of the present invention is to provide an intake device for an engine that can optimize an intake flow balance with a simple configuration.

The present invention solves the above-described problems by the following means.
The invention of claim 1 is arranged to be inclined with respect to a cylinder in which a piston is inserted and provided with a combustion chamber, introduces combustion air into the combustion chamber, and the region on the cylinder side branches into a plurality of flow paths. An intake port, an intake valve that is driven by a valve drive mechanism to open and close an end of the intake port on the combustion chamber side, and a cross-section of the flow path upstream from the branching point of the intake port. A partition section divided into the valve drive mechanism side and a flow path control provided on the upstream side of the partition section in the intake port, and opens and closes the cylinder side region of the cross section of the flow path of the intake port according to the operating state An intake device for an engine comprising a valve, wherein the downstream end position of the partition wall in the longitudinal direction of the intake port is changed along the width direction of the intake port. Jin is the intake system.

According to a second aspect of the present invention, a concave portion is formed in a central portion in the width direction of the intake port at the downstream end portion of the partition wall portion. The concave portion is recessed upstream of the other portions. It is an intake device of the engine described in 1.
The invention according to claim 3 is characterized in that an extending portion extending downstream from the other portion is formed at a central portion in the width direction of the intake port at the downstream end of the partition wall. The engine intake device according to claim 1.

In a state where the flow path control valve is closed, the flow rate is higher on the valve drive mechanism side than on the cylinder side with respect to the partition wall, so that the pressure is lowered. Therefore, immediately after the end portion of the partition wall, an air flow that flows from the cylinder side to the valve drive mechanism side and has a partition wall normal component is generated.
According to the present invention, by changing the downstream end position of the partition wall portion in the longitudinal direction of the intake port along the crankshaft axial direction, the air flow having such a partition normal component is The terminal position can be concentrated in the region arranged upstream of the other part. In such a region, a strong air flow is formed from the cylinder side (deck side) to the valve drive mechanism side.

  On the other hand, the main flow of combustion air flowing on the valve drive mechanism side with respect to the partition has a tendency to change in distribution so as to avoid such an air flow in the normal direction of the partition. As a result, the strength of the main flow flowing into the combustion chamber can be increased in the region where the end position of the partition wall portion extends to the downstream side with respect to the other portion.

  In the present invention, if the rear end edge of the partition wall is straightened by using the above-described characteristics, the rear end of the partition wall is recessed upstream and the main stream is reversed at a location where the main flow is too strong. In a place where the flow of air becomes weak, the rear end of the partition wall is extended downstream, whereby the intake flow balance can be improved with a simple configuration.

  For example, in the case of an engine that tends to have a strong flow in the central portion of the intake port (inside the valve), the downstream end of the partition wall is positioned in the central portion in the width direction of the intake port and more upstream than the other portions. By forming the recessed portion (notch portion) that is recessed, it is possible to optimize the intake flow balance.

  In addition, in the case of an engine that tends to have a strong flow at both ends of the intake port (outside the valve), the downstream end of the partition wall is positioned at the center in the width direction of the intake port and further downstream than the other portions. By forming the stretched stretched portion, it is possible to optimize the intake flow balance.

It is sectional drawing which cut | disconnected the internal shape of the cylinder of an engine provided with Example 1 of the intake device of the engine to which this invention was applied, an intake port, etc. with the symmetry plane. 2 is a perspective view of a cylinder, an intake port, and the like in the engine of Embodiment 1. FIG. It is the perspective view which looked at the intake port in Example 1, Example 2 of this invention, and the comparative example of this invention from the valve drive mechanism side. In addition, Example 1, Example 2, and a comparative example are shown to Fig.3 (a), FIG.3 (b), and FIG.3 (c), respectively. (Same in FIGS. 5 and 6) FIG. 3 is a schematic diagram illustrating an example of an airflow on a plane of symmetry of the engine of the first embodiment. It is a figure which shows the flow-velocity distribution of the partition normal direction in the intake port of Example 1, Example 2, and a comparative example. It is a figure which shows the flow velocity distribution of the mainstream along the longitudinal direction of the intake port of Example 1, Example 2, and a comparative example. It is a graph which shows transition of the tumble ratio according to the crank angle in Example 1 and a comparative example.

  It is an object of the present invention to provide an engine intake device capable of optimizing the intake flow balance with a simple configuration, by extending or shortening a part of a downstream end portion of a partition partitioning up and down in a port, It was solved by controlling the airflow strength in the direction.

A first embodiment of an engine intake device to which the present invention is applied will be described below.
The engine in the first embodiment is, for example, a 4-stroke gasoline engine used as a driving power source for automobiles such as passenger cars, and has a pent roof type combustion chamber having two intake valves and two exhaust valves.
FIG. 1 is a cross-sectional view of internal shapes of a cylinder, an intake port, and the like of an engine according to the first embodiment, cut along a symmetrical plane. The symmetry plane refers to a plane that is orthogonal to the rotation axis direction of the crankshaft and includes the center axis of the cylinder.
FIG. 2 is a perspective view of the inner shape of the cylinder and intake port of FIG.
FIG. 3A is a perspective view of the intake port of FIG. 1 viewed from the valve drive mechanism side.

As shown in FIG. 1 and the like, the engine includes a cylinder 10, a piston 20, a head 30, an intake port 40, an intake valve 50, an exhaust valve 60, and the like, and combustion formed by the cylinder 10, the piston 20, the head 30, and the like. A chamber 100 is provided.
The cylinder 10 is formed in a substantially cylindrical shape, and is formed by, for example, an inner peripheral surface of a cast iron sleeve inserted into a cylinder block made of an aluminum alloy.

  The piston 20 is a member that is inserted into the cylinder 10 and reciprocates along the center axis direction of the cylinder 10. The piston 20 is connected to a crankshaft (not shown) and a connecting rod (not shown).

  The head 30 is provided at the end of the cylinder 10 opposite to the crankshaft, and forms the combustion chamber 100 in cooperation with the crown surface of the piston 20 and the like. The head 30 is provided with an intake port 40, an exhaust port (not shown), a valve drive mechanism, and the like.

The intake port 40 is a flow path for introducing combustion air (fresh air) into the combustion chamber 100. In the case where the engine is a port injection type or a method using both in-cylinder direct injection and port injection, the intake port 40 is provided with a fuel injector (not shown).
The intake port 40 is disposed so as to be inclined with respect to the central axis of the cylinder 10, and the end portion on the combustion chamber side is bifurcated and is curved so that the valve drive mechanism (not shown) is convex. Has been. The outer wall surface portion of the curved portion is disposed adjacent to an exhaust port (not shown).
The intake port 40 is provided with a partition wall 41 and a control valve 42.
The partition wall 41 bisects the flow path in the intermediate portion upstream from the branch portion of the intake port 40 into the cylinder side (lower side / deck side in FIG. 1) and the valve drive mechanism side (upper side in FIG. 1). To do.

The downstream side (combustion chamber side) end of the partition wall 41 has a notch (recessed part) having a substantially V-shaped edge so that the central part in the crankshaft axial direction is recessed upstream with respect to other parts. ) 41a is formed. The edge portion of the notch 41a is disposed, for example, with an inclination of about 30 degrees with respect to the axial direction of the crankshaft.
Moreover, the notch 41a is arrange | positioned upstream from the branch location where the intake port 40 branches in two.
The effect of the notch 41a will be described in comparison with the comparative example of the present invention, together with the effect of the extending portion 41b of Example 2 described later.

  The control valve 42 is provided on the upstream side of the partition wall 41, and substantially closes the flow path on the cylinder 10 side of the partition wall 41 when the engine is in a predetermined operation state such as when the load is low. . The control valve 42 is driven by an actuator (not shown) that is controlled by an engine control device (not shown), and opens and closes the flow path by swinging about a rotation axis arranged substantially parallel to the central axis of the crankshaft.

The intake valve 50 opens and closes the bifurcated branch of the intake port 40 on the combustion chamber 100 side.
The intake valve 50 includes a valve body 51 and a stem 52 that are integrally formed.
The valve body 51 is formed in an umbrella shape or a disk shape, and opens and closes an end portion of the intake port 40. Further, the surface portion of the valve body 51 inside the cylinder 10 constitutes a part of the wall portion of the combustion chamber 100.
The stem 52 is a cylindrical shaft portion that protrudes from the valve body 51 and is inserted into a stem guide provided in the intake port 40.
The intake valve 50 is driven at the end of the stem 52 by a valve drive mechanism such as a camshaft (not shown), reciprocates in the axial direction of the stem 52 in synchronization with the rotation of the crankshaft, and opens and closes the intake port 40.

The exhaust valve 60 is driven to open and close by a valve drive mechanism, and opens and closes an exhaust port (not shown). A surface portion inside the cylinder 10 of the exhaust valve 60 constitutes a part of a wall portion of the combustion chamber 100.
Two intake valves 50 and two exhaust valves 60 are provided. A pair of intake valves 50 adjacent to each other with the plane of symmetry interposed therebetween and a pair of exhaust valves 60 adjacent to each other across the plane of symmetry are disposed adjacent to each other with the stem directions parallel to each other. Further, the intake valve 50 and the exhaust valve 60 are arranged in a state in which the direction of the stem is opened by a predetermined valve opening angle.

Next, a second embodiment of the engine intake device to which the present invention is applied will be described.
In addition, in Example 2 and the comparative example of this invention mentioned later, the same code | symbol is attached | subjected to the location substantially the same as Example 1 mentioned above, description is abbreviate | omitted, and a difference is mainly demonstrated.

The engine intake device of the second embodiment includes an extending portion 41b shown in FIG. 3B instead of the above-described notch portion 41a at the rear edge of the partition wall 41 of the first embodiment.
The extending portion 41b extends the central portion of the partition wall 41 in the width direction of the intake port 40 toward the downstream side (combustion chamber 100 side) with respect to the other portions. The rear edge of the partition wall 41 in the extending portion 41b is formed in a substantially V shape as shown in FIG.

Hereinafter, the effects of the first and second embodiments will be described in comparison with comparative examples of the present invention described below.
The engine intake device of the comparative example of the present invention is such that the rear end edge of the partition wall 41 in the first embodiment is formed straight along the width direction (crankshaft axial direction) of the intake port 40.

FIG. 4 is a schematic diagram illustrating an example of the airflow on the symmetry plane of the engine of the first embodiment with the control valve 42 closed. FIG. 4A is a diagram showing the main part of the intake port 40 and the entire inside of the cylinder 10, and FIG. 4B is an enlarged view of a part b of FIG. 4A.
In the state where the control valve 42 is closed, a drift is formed on the valve drive mechanism side (upper side in the figure) of the partition wall 41. On the valve drive mechanism side of the partition wall 41, the flow rate of the combustion air along the longitudinal direction of the intake port 40 is faster than the cylinder side, so the pressure is lower.
Due to the pressure difference between both sides of the partition wall 41, an air flow having a normal direction component of the partition wall 41 is formed on the downstream side of the partition wall 41 from the cylinder side to the valve drive mechanism side. (Refer to part A in FIG. 4 (b))

FIG. 5 is a view showing the flow velocity distribution in the normal direction of the partition walls in the intake ports of the first embodiment, the second embodiment, and the comparative example with the control valve 42 closed. In the figure, a region surrounded by a broken line indicates a region where the flow velocity is 3 m / s or more.
When the notch 41a is formed as in the first embodiment shown in FIG. 5A, a region where the flow velocity in the normal direction of the partition wall is high is formed at the center of the intake port 41 immediately after the notch 41a.
Further, as in the second embodiment shown in FIG. 5B, when the extending portion 41b is formed, the region where the flow velocity in the normal direction of the partition wall is high is near both side walls of the intake port 40 sandwiching the extending portion 41b. In FIG.
On the other hand, as in the comparative example shown in FIG. 5C, when the rear edge of the partition wall 41 is formed straight, the flow velocity in the normal direction of the partition wall as in Examples 1 and 2 is partially high. Regions are difficult to form.

  FIG. 6 is a diagram illustrating the flow velocity distribution of the main flow along the longitudinal direction of the intake ports of the first embodiment, the second embodiment, and the comparative example when the control valve 42 is closed. In the figure, a region surrounded by a broken line indicates a region where the flow velocity is 40 m / s or higher, and a region surrounded by a one-dot chain line indicates a region where the flow velocity is 0 m / s or higher.

In the first embodiment, as shown in FIG. 5 (a), a region where the flow velocity in the normal direction of the partition wall is high is formed in the central portion in the width direction (crankshaft axis direction) of the intake port. The distribution of the main flow of combustion air along the longitudinal direction of the intake port 40 changes on both sides in the width direction of the intake port 40 while avoiding this central portion.
As a result, as indicated by a hollow arrow in FIG. 6A, the airflow flowing from the central portion of the intake port 40 to the inside of the two intake valves 50 is weakened, while the intake valve 50 from both ends of the intake port 40 is weakened. The airflow that flows outside is strengthened.
In the first embodiment, when the intake device of the comparative example is applied, the air flow from the central portion of the intake port 40 is strong, and the intake flow balance is biased so that sufficient tumble cannot be obtained. Suitable for increasing balance and tumble.

FIG. 7 is a graph showing the transition of the tumble ratio according to the crank angle in Example 1 and the comparative example, where the horizontal axis shows the crank angle and the vertical axis shows the tumble ratio.
As shown in FIG. 7, in the first embodiment, a stronger tumble can be obtained from the crank angle (ATDC) 80 ° or later, which is the middle stage of the intake stroke, and the intake valve 50 is closed and compressed. While the process is being performed, a strong tumble can be maintained with respect to the comparative example, and the combustion state can be improved to improve the output, fuel consumption, exhaust gas, and the like.
In particular, since the tumble strength at around 320 to 350 °, which is the latter stage of the compression stroke and immediately before the ignition timing, is stronger than that of the comparative example, the combustion improvement effect is remarkable.

In the second embodiment, as shown in FIG. 5B, regions where the flow velocity in the normal direction of the partition wall is high are formed at both ends in the width direction (crankshaft axial direction) of the intake port. The distribution of the main flow of combustion air along the longitudinal direction of the intake port 40 changes at the center in the width direction of the intake port 40 while avoiding the both ends.
As a result, as shown by a hollow arrow in FIG. 6B, the airflow flowing from the center of the intake port 40 to the inside of the two intake valves 50 is strengthened, while the intake valve 50 from both ends of the intake port 40. The airflow that flows outside is weakened.
In the second embodiment, if the intake device of the comparative example is applied, the air flow from the center of the intake port 40 is weak, and the intake flow balance is biased so that sufficient tumble cannot be obtained. Suitable for increasing balance and tumble.
As described above, according to the engine intake devices of the first and second embodiments, the intake flow balance can be optimized with a simple configuration.
Further, the shape of the downstream end portion of the partition wall 41 as described above has little influence on the flow coefficient when the control valve 42 is opened.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
For example, the shape of the rear end edge of the partition wall is not limited to the configuration as in the first and second embodiments, and can be changed as appropriate. For example, the shape of the rear edge of the partition wall is not limited to the V shape described above, and may be formed in a step shape or a curved shape. Moreover, you may comprise combining several extending | stretching parts and several notch parts.
In addition, the engine intake device of the present invention can be used not only for strengthening the tumble as described above, but also for the purpose of intentionally suppressing the tumble flow, for example, in a direct injection engine.

DESCRIPTION OF SYMBOLS 10 Cylinder 20 Piston 30 Head 40 Intake port 41 Partition 41a Notch 41b Extending part 42 Control valve 43 Partition 50 Intake valve 51 Valve body 52 Stem 60 Exhaust valve 100 Combustion chamber

Claims (3)

An intake port in which a piston is inserted and is inclined with respect to a cylinder in which a combustion chamber is provided, introduces combustion air into the combustion chamber, and an area on the cylinder side branches into a plurality of flow paths;
An intake valve that is driven by a valve drive mechanism to open and close an end of the intake port on the combustion chamber side;
A partition that divides the cross section of the flow path upstream of the branch point of the intake port into the cylinder side and the valve drive mechanism side;
An engine intake device comprising: a flow path control valve provided upstream of the partition wall in the intake port and opening and closing a region on the cylinder side of a flow path cross section of the intake port according to an operating state. ,
An intake system for an engine, wherein a downstream end position of the partition wall in the longitudinal direction of the intake port is changed along the width direction of the intake port. 2. The engine intake device according to claim 1, wherein a concave portion that is recessed upstream of the other portion is formed in a central portion of the end portion on the downstream side of the partition wall portion in the width direction of the intake port. . 2. The engine intake air according to claim 1, wherein an extension portion extending downstream from the other portion is formed in a central portion in the width direction of the intake port at an end portion on the downstream side of the partition wall portion. apparatus.

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