JP2007040232A - Engine intake device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine intake device, wherein an opening area in a region toward the inclination of a stem is larger than an opening area in a region on the opposite side to properly form a desired flow in a combustion chamber. <P>SOLUTION: The engine intake device comprises an intake valve 30 having an umbrella portion 30a for opening/closing an opening portion 26a open to a cylinder 12 and the stem 30b extending to a direction inclined at a predetermined angle to an axis α of the umbrella portion 30a, and a valve train 34 for moving the intake valve 30 forward/backward in the longitudinal direction of the stem 30b. When the intake valve is at an opening position, the opening area of the opening portion is deflected. Namely, the opening area in the region toward the inclination of the stem is larger than the opening area in the region on the opposite side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an engine intake device that includes an intake valve that opens and closes an intake port facing a combustion chamber, and a valve mechanism that drives the intake valve.

  Conventionally, in order to improve the combustion of the engine, the flow of air taken into the combustion chamber has been controlled. For example, according to Patent Document 1, a rectifying plate is provided so as to be rotatable about the intake valve so as to cross an opening between the intake valve and the wall surface of the intake port, and the air flowing into the combustion chamber tends to have a forward tumble tendency. It has been proposed to rotate the current plate to a predetermined position in accordance with the operating state so that a reverse tumble flow or swirl flow is formed.

Japanese Patent Laid-Open No. 10-331647

  However, in the thing of the said patent document 1, since a clearance gap arises in the circumference | surroundings of a baffle plate with the lift of a valve | bulb, for example, in order to form a reverse tumble flow, When the direction of the rectifying plate is set so that the opposing area is maximized, as the lift amount of the intake valve increases, from the gap around the rectifying plate, in addition to the cylinder side wall of the intake port, the top of the cylinder There is a high possibility that a large amount of air flows from the side to the combustion chamber. As a result, the air flowing in the direction of the reverse tumble flow and the air flowing in the direction of the forward tumble flow are generated together, and they collide with each other, and the reverse tumble flow may not be properly formed in the combustion chamber. is there.

  Therefore, an object of the present invention is to provide a novel means for appropriately forming a desired flow in a combustion chamber.

  In order to solve the above-described problems, an intake device for an engine according to the present invention includes an umbrella portion that opens and closes an opening portion opened in a cylinder, and an intake valve that has a stem extending in a direction inclined at a predetermined angle with respect to the axis of the umbrella portion. And a valve operating mechanism for moving the intake valve back and forth in the longitudinal direction of the stem.

  With the above configuration, when the intake valve is in the open position, the opening area of the opening is deflected. That is, the opening area of the region in the direction of inclination of the stem is larger than the opening area of the region on the opposite side. Therefore, according to the present invention, a desired flow can be formed in the combustion chamber by the air or air-fuel mixture from the intake port.

  The stem according to the present invention may be positioned so as to extend in a region opposite to the axis of the cylinder with respect to the central axis of the opening. In this case, when the intake valve is in the open position, the cylinder wall surface side portion of the opening opens larger than the cylinder top side portion. Therefore, air from the intake port mainly flows toward the cylinder wall surface, and a reverse tumble flow is appropriately formed in the combustion chamber.

  According to the engine intake device of the present invention, a reverse tumble flow is appropriately formed in the combustion chamber regardless of the lift amount of the intake valve.

  Hereinafter, an engine intake device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The tumble flow is a flow of intake air swirling in a plane substantially parallel to the cylinder axis. In the following description, the tumble flow is opposed from the intake valve along the combustion chamber wall surface of the cylinder head. That flows to the cylinder wall surface, collides with the cylinder wall surface, descends in the direction of the piston top surface, and then rises back to the intake valve side and returns to the intake valve side. , And descends toward the top surface of the piston, returns to the intake valve side through the cylinder wall surface facing the cylinder wall surface and the combustion chamber wall surface of the cylinder head, and is called reverse tumble flow.

  FIG. 1 is a schematic plan view around an engine 10 to which an intake device for an engine according to an embodiment of the present invention is applied. FIG. 2 is a partial longitudinal section of the engine 10 cut along the line AA in FIG. FIG. The engine 10 of this embodiment is a gasoline engine provided with four cylinders (cylinders) 12 of # 1 to # 4 in series. However, not limited to this example, the engine may be a 6-cylinder or 8-cylinder engine, a diesel engine, or a V-type engine. As described above, the engine to which the present invention is applied is not particularly limited in the number of cylinders and the type of the engine.

  The engine 10 is a four-valve engine in which two camshafts open and close two intake valves and two exhaust valves, respectively. In FIG. 1, an intake manifold 10 u is provided on the intake side of the engine 10. An exhaust manifold 10d is connected to the exhaust side. 1 and 2, the fuel injection valve for port injection is omitted.

  The engine 10 includes a cylinder block 16 in which four cylinders 12 and a cooling water passage 14 are formed, and a cylinder head 18 fixed to the upper portion of the cylinder block 16. In the cylinder block 16, a piston 20 is slidably loaded in each cylinder 12. A rotatable crankshaft (not shown) serving as an engine output shaft is connected to the piston 20 via a connecting rod 22.

  The cylinder head 18 is formed with an intake port 26 and an exhaust port 28 respectively facing the combustion chamber 24 of each cylinder 12. The cylinder head 18 incorporates a valve mechanism 34 that drives an intake valve 30 that opens and closes the intake port 26 and an exhaust valve 32 that opens and closes the exhaust port 28, and an ignition plug 36 that ignites the air-fuel mixture in the combustion chamber 24. In addition, an ignition coil (not shown) for generating sparks is mounted on the spark plug 36. In the valve operating mechanism 34, the intake camshaft 38 and the exhaust camshaft 40 disposed in the cylinder head 18 are driven by a crankshaft via a belt (not shown).

  In the present embodiment, the cams 42 and 44 that rotate with the rotation of the camshafts 38 and 40 are arranged to push the valve lifters 46 and 48 directly. As shown in FIG. 2, the intake valve 30 is inserted through the valve guide 50. The intake valve 30 is constantly urged in a direction to close the intake port 26 by a valve spring 52 held in a compressed state by a valve spring retainer 51. Similarly, the exhaust valve 32 is inserted into the valve guide 54 and urged by the valve spring 56 in the direction of closing the exhaust port 28. Accordingly, when the cam 42 is rotated, the intake valve 30 is pressed via the valve lifter 46 to open and close the opening that opens to the cylinder 12, that is, the opening 26a of the intake port 26 to the combustion chamber 24. To do. Similarly, the exhaust valve 32 opens and closes the opening 28 a of the exhaust port 28 to the combustion chamber 24.

  As shown in the enlarged view of the intake valve in FIG. 3, the intake valve 30 of the present embodiment has an umbrella portion 30 a that opens and closes an opening 26 a that opens in the cylinder 12, and a predetermined axis with respect to the axis α of the umbrella portion 30 a. It has a stem 30b extending in a direction inclined at an angle. The axis α of the umbrella portion 30a passes through the center of the umbrella portion 30a, that is, the center O of the valve face 30c, and is orthogonal to the line β passing through the center O in parallel with the valve head 30d. On the other hand, the stem axis γ forms an acute angle δ with the line β. The valve mechanism 34 allows the intake valve 30 to advance and retreat in the longitudinal direction of the stem 30b, that is, in the direction of the axis γ.

  According to FIG. 2, the stem 30 b of the intake valve 30 is positioned so as to extend in a region opposite to the cylinder axis Y with respect to the central axis X of the opening 26 a that opens to the cylinder 12. The axis of the umbrella portion 30 a coincides with the central axis X of the opening 26. The cam 42 is disposed on the cylinder head 18 that deviates from the cylinder extension. Therefore, the stem 30b of the intake valve 30 extends from the umbrella portion 30a in the direction away from the cylinder axis Y so as to be substantially in the radial direction of the cylinder 12. The intake camshaft 38 of the cam 42 is disposed at a position farther from the cylinder axis Y than the intake port 26, and the stem 30 b of the intake valve 30 is opposite to the exhaust port 28 across the cylinder axis Y and the intake port 26. Will be positioned on the side.

  The direction of the stem 30b of the intake valve 30 is schematically shown in FIG. According to FIG. 4 schematically showing the state of the cylinder 12 as viewed from above the cylinder axis Y, the stem 30b of the intake valve 30 substantially overlaps the direction of the intake port 26, and can move forward and backward toward the cylinder axis Y. It is understood that it is positioned. In other words, the direction of the intake valve 30 is positioned so that the umbrella portion 30a approaches the cylinder axis Y when the intake valve 30 protrudes. However, the present invention does not limit the direction of the stem 30b of the intake valve 30 to the direction shown in FIG. 4, and the forward / backward movement direction of the intake valve 30 is determined by the cylinder axis Y in plan view from above the cylinder axis Y. You may make it correspond with the radiation | emission direction from. 4, the movement direction of the stem 32b of the exhaust valve 32 shown together with the intake valve 30 coincides with the radial direction from the cylinder axis Y in a plan view from above the cylinder axis Y.

  The operation of the intake valve 30 will be described below with reference to FIG. FIG. 5 is an enlarged view schematically showing the periphery of the combustion chamber 24 in FIG. In FIG. 5, the intake valve 30 is advanced in the direction approaching the cylinder axis Y, and the opening 26a of the intake port 26 is opened. According to this, it is understood that the intake valve 30 opens the cylinder wall surface side portion S1 of the opening 26a larger than the cylinder top side portion S2. This means that when the intake valve 30 is in such an open position, the opening area of the opening 26a is deflected. That is, the opening area of the region of the stem 30b in the inclination direction is larger than the opening area of the region on the opposite side.

  As a result, the air from the intake port 26 mainly flows into the combustion chamber 24 from the cylinder wall surface side portion S1 of the opening 26a, as indicated by an arrow in the cylinder 12 in FIG. Since the cylinder top portion S2 of the opening 26a is maintained in an almost unopened state even if the opening 26a is opened (see FIG. 5), from the cylinder top portion S2 to the combustion chamber 24, Little or no air will flow in. Accordingly, the air to the combustion chamber 24 first descends from the intake valve 30 toward the top surface of the piston, and returns to the intake valve 30 side through the opposing cylinder wall surface and combustion chamber wall surface, that is, reverse tumble flow. Form.

  The further effect by forming a reverse tumble flow will be described below. In the following, the drawings schematically showing the engine 10 around the combustion chamber 24 in the above embodiment will be used for the description.

  First, it will be described that, by forming a reverse tumble flow according to the above embodiment, turbulence can be appropriately generated in the air or air-fuel mixture in the combustion chamber 24 at the latter stage of the compression stroke. Before describing what is in the present embodiment, a conventional engine intake device, which is a comparative reference, that is, an engine intake device having an intake valve 30 ′ in which the axis of the umbrella and the axis of the stem coincide with each other. The case where is applied will be described with reference to FIG. FIG. 6 schematically shows that the intake valve 30 ′ is advanced to the piston 20 side and the intake port 26 is opened. The lift amount of the intake valve 30 ′ in FIG. The lift amount is smaller than that in FIG. When the lift amount is small, air may enter the combustion chamber 24 mainly from the cylinder wall surface side (see arrow a1 in FIG. 6A), but also from the cylinder top side as the lift amount increases. Equivalent air will enter (see arrow a2 in FIG. 6B). Therefore, there may occur a case where the two flows a1 and a2 can interfere with each other and cancel each other, so that it is difficult to form a strong flow in the air-fuel mixture in the combustion chamber 24.

  On the other hand, according to the embodiment as described above, since the reverse tumble flow is mainly formed in the combustion chamber 24 (see FIG. 5), a flow strong against the air-fuel mixture in the combustion chamber 24 is formed. It will be. Therefore, in the latter stage of the compression stroke in which the piston 20 rises toward the cylinder head 18, the compression force by the piston 20 is added to the strong flow of the air-fuel mixture, and therefore the reverse tumble flow is disturbed as the compression stroke proceeds. This makes it possible to generate a strong turbulent flow in the air-fuel mixture in the cylinder (see the arrow in FIG. 7). Since ignition is performed when the air-fuel mixture is disturbed in this way, flame propagation after ignition is promoted, that is, the combustion speed is increased, and the combustion efficiency can be further increased.

  Furthermore, according to the thing of the said embodiment, another effect is show | played. For example, as shown in FIG. 8, in an engine 10 ′ in which fuel is directly injected into the combustion chamber 24 and provided with a so-called in-cylinder fuel injection valve 58, fuel may adhere to the top of the piston 20. . In particular, when the engine 10 ′ having such a configuration performs a homogeneous combustion operation, the fuel is injected from the fuel injection valve 60 in the first half of the intake stroke, and thus is relatively close to the fuel injection valve 60. There is a possibility that the fuel injected from the fuel injection valve 60 adheres to the top of the piston 20. Since such an adhering fuel F may not be used to form an air-fuel mixture, for example, it may cause smoke after the air-fuel mixture ignition (see FIG. 8A). . However, according to the above-described embodiment, as described above, a reverse tumble flow that is a strong flow is formed, so that the flow promotes the detachment of the attached fuel F, suppresses the fuel adhesion, and improves the combustion efficiency. It becomes possible to make it. As described above, when the conventional intake valve 30 'is used, a strong flow is not generated in the air-fuel mixture, so that the desorption of the attached fuel F is inferior to that in the present embodiment.

  On the other hand, when the intake valve 30 is configured as in the above-described embodiment, the amount of protrusion of the intake valve 30 toward the piston 20 can be reduced, thereby providing an excellent effect. This will be described with reference to FIG. 9. FIG. 9A shows a case where the conventional intake valve 30 ′ is provided, and FIG. 9B shows a case where the intake valve 30 of the above embodiment is provided. . According to FIG. 9A, when the intake valve 30 ′ is opened with the piston 20 raised, it is necessary to provide a recess, that is, a recess R, on the surface of the piston 20 in order to prevent the contact. This will result in an increase in the surface area of the piston top and an increase in the minimum volume of the combustion chamber 24. On the other hand, according to FIG. 9B showing the application of the intake valve 30 according to the above embodiment, as described above, the protrusion amount of the intake valve 30 toward the piston 20 can be reduced, so that the recess R Need not be provided on the top of the piston 20, the surface area of the piston 20 can be suppressed, and the cooling loss can be reduced. Further, since the amount of protrusion of the intake valve 30 toward the piston 20 can be reduced, the minimum volume of the combustion chamber 24 can be reduced, the compression ratio of the cylinder 12 can be increased, and the engine output can be improved. Become.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to this. For example, the present invention is not limited to those using liquid fuel, but can be applied to any spark ignition type internal combustion engine such as an engine using gaseous fuel. The present invention does not exclude application to a compression ignition internal combustion engine. In the above embodiment, the valve mechanism 34 of the engine 10 is such that the intake camshaft 38 is rotated by the belt and the intake valve 30 is moved. For example, a solenoid controlled by an output signal from the control device. May be used to move the intake valve 30, and any technique can be applied to the valve operating mechanism 34. In the above embodiment, the present invention is applied to a four-valve engine. However, the present invention is also applicable to a two-valve engine, for example.

  In the above embodiment, the stem 30b of the intake valve 30 is positioned so as to extend in a region opposite to the cylinder axis Y with respect to the central axis X of the opening 26a of the intake port 26. May be positioned so as to extend in a region opposite to the center axis X on the cylinder axis Y side. When the intake valve 30 is moved under such a configuration, the cylinder top portion S2 of the opening 26a opens larger than the cylinder wall surface portion S1, for example, a positive tumble in the combustion chamber 24. A flow can be formed. Further, for example, the swirl flow can be realized by applying the intake valve 30 to the two-valve engine and positioning the stem 30b in a direction orthogonal to the radial direction from the cylinder axis Y.

  Although the present invention has been described with a certain degree of specificity in the above-described embodiments and modifications, various modifications can be made to the present invention without departing from the spirit and scope of the invention described in the claims. It must be understood that changes are possible. That is, the present invention includes modifications and changes that fall within the scope and spirit of the appended claims and their equivalents.

1 is a schematic plan view around an engine to which an engine intake device according to an embodiment of the present invention is applied. FIG. 2 is a longitudinal sectional view around one cylinder of the engine shown in FIG. 1. It is a side view of the intake valve concerning this embodiment. It is a cross-sectional top view which shows the state which has arrange | positioned the intake valve in one cylinder. It is a longitudinal cross-sectional view which shows the state which the intake valve opened. It is a schematic diagram which shows the state using the intake device of the conventional engine, (a) is a figure which shows the case where the lift amount of an intake valve is small, (b) is the case where the lift amount of an intake valve is large. It is a schematic diagram of the latter half of the compression stroke around the combustion chamber according to the present embodiment. It is a schematic diagram which shows the state which applied the intake valve which concerns on this embodiment, (a) is a state where the fuel adhered, (b) is a figure which shows the state which the fuel detached | desorbed. (A) It is a schematic diagram which shows the state which applied the conventional intake valve, (b) is a figure which shows the state which applied the intake valve which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 12 Cylinder 14 Cooling water path 16 Cylinder block 18 Cylinder head 20 Piston 22 Connecting rod 24 Combustion chamber 26 Intake port 26a Opening part 28 Exhaust port 30 Intake valve 30a Umbrella part 30b Stem 32 Exhaust valve 34 Valve mechanism 36 Spark plug 38 Intake Camshaft 40 Exhaust camshaft 42, 44 Cam 46, 48 Valve lifter 50, 54 Valve guide 52, 56 Valve spring 58 In-cylinder fuel injection valve α Umbrella axis γ Stem axis X Opening center axis Y Cylinder Axis

Claims (2)

An intake valve having an umbrella part that opens and closes an opening part opened in the cylinder and a stem that extends in a direction inclined at a predetermined angle with respect to the axis of the umbrella part;
A valve mechanism for moving the intake valve forward and backward in the longitudinal direction of the stem;
An intake system for an engine characterized by comprising: The engine intake device according to claim 1, wherein the stem is positioned so as to extend in a region opposite to the axis of the cylinder with respect to a central axis of the opening.

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