JP2010133271A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine for preventing deterioration of fuel consumption due to an air intake flow passage mechanism, when a closing timing of an air intake valve is retarded. <P>SOLUTION: In an internal combustion engine with variable valve mechanism, a reverse flow adjusting mechanism is provided for causing gas on the downstream side to circulate to the upstream side of the air intake flow passage mechanism, when a pressure on the downstream side of an air intake flow passage mechanism provided in an air intake passage rises. Thereby pumping loss of a piston is avoided from occurring, thus deterioration of fuel consumption can be prevented. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an internal combustion engine capable of controlling in-cylinder flow in a fuel chamber.

  2. Description of the Related Art An internal combustion engine that changes the opening / closing timing of an intake valve and an exhaust valve according to an operating state or the like is known. For example, it is known that when the closing timing of the intake valve is delayed, the pumping loss due to the piston is reduced and the fuel consumption of the internal combustion engine is improved. On the other hand, if the intake valve is opened for a long time, the actual compression ratio may be reduced, or the fluidity of the sprayed fuel or intake air in the cylinder may be reduced, leading to deterioration in combustion in the cylinder.

Therefore, a flow restriction valve that narrows the opening cross-sectional area of the intake passage is provided in the intake passage, and when the flow velocity is slow, the intake passage is narrowed by the flow restriction valve to increase the air flow velocity, and the air flowing into the cylinder It is considered to improve the combustion by increasing the flow velocity or by actively stirring the air flow (including the air-fuel mixture) in the cylinder. (See Patent Document 1.)
JP-A-2001-3755

  However, if the closing timing of the intake valve is delayed and the piston is open until it rises in the cylinder, the pressure in the cylinder starts to rise, and the air flow that flows out of the combustion chamber through the opened intake valve Back flow inside. At this time, if the flow path restriction valve narrows the opening cross-sectional area of the intake passage, the air flowing backward in the intake passage is blocked by the flow restriction valve. As a result, the pressure on the downstream side of the flow path restriction valve, that is, the pressure inside the cylinder is increased, the pumping loss is increased, and the fuel consumption is deteriorated.

  The present invention solves the above problems, and in an internal combustion engine in which at least the closing timing of the intake valve can be changed with respect to the crank angle and the intake passage adjustment mechanism is provided in the intake passage, the closing timing of the intake valve is delayed. Even in such a case, it is an object to provide an internal combustion engine with a variable valve mechanism that prevents the occurrence of a pumping loss due to an intake flow path adjustment mechanism and does not cause a deterioration in fuel consumption.

  The internal combustion engine includes an intake passage adjustment mechanism that reduces an opening cross-sectional area of the intake passage in an intake passage communicated with the combustion chamber. Further, the internal combustion engine includes reverse flow adjusting means for circulating the gas on the downstream side of the intake flow path adjusting mechanism from the downstream side to the upstream side of the intake flow path adjusting mechanism. As the backflow adjusting means, for example, a sub-passage having a check valve is used.

  Furthermore, the internal combustion engine has a variable valve mechanism that enables at least the opening timing of the intake valve that opens and closes the intake passage until the middle of the compression stroke. Then, the opening timing of the intake valve can be set until the middle of the compression stroke after the opening cross-sectional area of the intake passage is reduced by the intake passage adjustment mechanism.

  The internal combustion engine with a variable valve mechanism according to the present invention has the following effects.

  Even if a backflow of gas occurs from the downstream side to the upstream side of the intake flow path adjustment mechanism due to the operating state of the internal combustion engine, the reverse flow can be prevented from being inhibited by the intake flow path adjustment mechanism. Damage to the path adjustment mechanism can be suppressed.

  An embodiment of an internal combustion engine with a variable valve mechanism according to the present invention will be described with reference to the drawings. FIG. 1 shows a combustion chamber portion of the engine 10. The engine 10 is an internal combustion engine with a variable valve mechanism that includes a valve mechanism on an intake valve. The engine 10 uses gasoline as a main fuel, and includes an intake passage adjustment mechanism and a fuel injection device that injects fuel in the intake passage. The engine 10 is a naturally aspirated engine, but may be a supercharged engine equipped with a turbocharger or other supercharger. The engine 10 may be of a type provided with a direct fuel injection device in a cylinder.

  The combustion chamber portion of the engine 10 includes a cylinder head 12, a piston 14, a cylinder block 16 and the like as shown in FIG.

  The cylinder block 16 has a cylinder 18 inside. The number of cylinders 18 formed in the cylinder block 16 is not particularly limited. A piston 14 is provided in the cylinder 18 so as to be reciprocally movable. A cylinder head 12 is fixed to the upper surface of the cylinder block 16 with bolts (not shown).

  The cylinder head 12 has a recess 20 for a combustion chamber on the lower surface. The recess 20 has a triangular cross section, and forms a combustion chamber 26 of the engine 10 in a space defined by the recess 20, the top surface 22 of the piston 14, and the inner surface of the cylinder 18.

  The cylinder head 12 is provided with an intake passage 28 and an exhaust passage 30. The intake passage 28 is connected to an air cleaner (not shown) on the upstream side, and an intake valve 32 is provided at an opening (not shown) facing the combustion chamber 26. In the intake passage 28, a fuel injection device 40 and an intake flow path adjustment mechanism 42 are provided.

  The exhaust passage 30 communicates with the combustion chamber 26 via an exhaust valve 34, and an oxidation catalyst 44 and a diesel particulate filter (DPF) 46, for example, are connected to the downstream side of the exhaust passage 30 as exhaust purification means. ing. The exhaust purification means may be appropriately provided with a catalyst or filter corresponding to the target harmful substance, and is not limited to an oxidation catalyst and a diesel particulate filter (DPF).

  The intake valve 32 and the exhaust valve 34 are slidably attached to the cylinder head 12. The intake valve 32 is provided with an intake side valve mechanism 36, and the exhaust valve 34 is provided with an exhaust side valve mechanism 38. . The intake side valve mechanism 36 and the exhaust side valve mechanism 38 operate in conjunction with the rotation of a crankshaft (not shown), respectively, to drive the intake valve 32 and the exhaust valve 34 in the axial direction. Thus, the intake passage 28 and the exhaust passage 30 are opened and closed at a predetermined time with respect to the combustion chamber 26 as the engine 10 is driven.

  Further, the intake side valve mechanism 36 includes a variable valve mechanism. Thereby, the intake side valve mechanism 36 can change the opening / closing timing of the intake valve 32 with respect to the position of the piston 14 in the cylinder 18, that is, the crank angle of the crankshaft, according to the operation content of the engine 10. It has become. The variable valve mechanism for changing the opening / closing timing of the intake valve 32 may be one using an electric motor or one using hydraulic pressure, and the mechanism is not limited. Further, an electric actuator or the like may be directly attached to the intake valve 32 so that the intake valve 32 is directly opened and closed at an arbitrary timing. The intake side valve mechanism 36 is configured so that at least the closing timing of the intake valve 32 can be changed, but is not limited thereto. Further, the exhaust side valve mechanism 38 may change the opening / closing timing of the exhaust valve 34 with respect to the exhaust valve 34 in the same manner as the intake side valve mechanism 36.

  The fuel injection device 40 is a fuel injection device in the intake passage, which has an injection hole at the tip and has a valve mechanism (both not shown) inside. A fuel pipe 56 from the fuel tank 52 and a signal line 60 from the control means 58 are connected to the fuel injection device 40. The fuel tank 52 includes a fuel pump 62, and the fuel in the fuel tank 52 is pumped into the fuel pipe 56 at a predetermined pressure via the fuel pump 62. The fuel injection device 40 is attached with the injection hole facing the intake passage 28, and when the valve mechanism is operated in accordance with a signal sent via the signal line 60, the fuel sent from the fuel tank 52 is taken in. The fuel is injected into the passage 28 at a predetermined pressure. Note that the fuel may be pressurized by the fuel injection device 40 and injected into the intake passage 28. The term “injection” basically refers to radiating fuel in the form of a mist, but it may be injected in the form of a liquid column. Moreover, the injection position of the fuel injection device 40 is not particularly limited.

  The intake flow path adjustment mechanism 42 includes a movable valve plate 43 provided in the intake passage 28, a drive mechanism (not shown) that rotates the movable valve plate 43, and the like. The movable valve plate 43 is rotatably provided in the vicinity of the fuel injection device 40 in the approximate center of the intake passage 28. The movable valve plate 43 is integrally attached to the rotation shaft 45, and is rotated in the intake passage 28 when the rotation shaft 45 is rotated by a drive mechanism.

  The movable valve plate 43 is driven to rotate at an arbitrary angle from an open state, that is, a state parallel to the flow direction of the intake passage 28, to a closed state, that is, a state substantially perpendicular to the flow direction of the intake passage 28. When the movable valve plate 43 is set in the closed state, the open section of the intake passage 28 is substantially closed, leaving an open portion in the vicinity of the injection hole of the fuel injection device 40.

  Further, the cylinder head 12 is provided with an intake sub-passage 11 as a backflow adjusting means. The intake sub-passage 11 is a communication passage formed in parallel with the intake passage 28 across the intake passage adjustment mechanism 42. One end of the intake sub-passage 11 opens to the upstream side of the intake flow passage adjustment mechanism 42, that is, the side wall of the intake passage 28 opposite to the combustion chamber 26, and the other end of the intake sub-passage 11 is the intake flow passage Openings are respectively made in the side walls of the intake passage 28 on the downstream side of the adjustment mechanism 42.

  A one-way valve 13 as a flow path restricting unit is provided inside the intake sub-passage 11. The one-way valve 13 has a check valve whose valve function is closed from the upstream side to the downstream side (same as upstream and downstream of the intake passage 28), and in the opposite direction, the valve function is opened by pressure from the upstream side. It is. The intake sub-passage 11 may not be formed in the cylinder head 12 but may be configured outside the cylinder head 12 by using a separate pipe or the like.

  A spark plug 48 is attached to the cylinder head 12. The spark plug 48 has an electrode portion at the tip, and is attached to the cylinder head 12 at the substantially upper center of the combustion chamber 26 with the electrode portion facing the combustion chamber 26. The spark plug 48 is connected to the ignition mechanism 50, and discharges at an appropriate ignition timing by the action of the ignition mechanism 50. Note that the spark plug 48 may be attached to another position instead of the center of the combustion chamber 26.

  Next, the operation and effect of the engine 10 will be described.

  In the engine 10, when the crankshaft rotates, the piston 14 reciprocates in the cylinder 18. As the piston 14 reciprocates, the intake side valve mechanism 36 operates the intake valve 32, the exhaust side valve mechanism 38 operates the exhaust valve 34, and the fuel injection device 40 injects fuel into the intake passage 28. . The air-fuel mixture introduced into the combustion chamber 26 is ignited by a spark from the spark plug 48 and burned.

  For example, when the crank speed of the engine 10 is low and the flow rate of intake air is low, the intake flow path adjustment mechanism 42 operates and the movable valve plate 43 reduces the opening cross-sectional area of the intake passage 28. Then, as shown in FIG. 2, the air flow passes through the open portion that is not closed by the movable valve plate 43, the speed increases, and the air flows into the combustion chamber 26 with a fast air flow (air mixture). Moreover, since this open part is the vicinity of the injection hole of the fuel injection device 40, the fuel injected from the fuel injection device 40 and air are mixed well.

  In order to improve fuel efficiency, the intake side valve mechanism 36 operates to delay the closing timing so that the closing timing of the intake valve 32 is after the middle of the compression stroke. FIG. 4 shows the opening / closing timing of the intake valve 32 and the exhaust valve 34 at that time. In FIG. 4, the horizontal axis represents the rotation angle of the crankshaft, the vertical axis represents the valve opening, the curve A represents the opening of the intake valve 32, and the curve B represents the opening of the exhaust valve 34. That is, as shown by the curve A, the intake valve 32 starts to open from 360 degrees and closes before 720 degrees.

  In this way, the intake valve 32 is open in the region where the crankshaft is in the range of 540 degrees to 720 degrees and the piston 14 originally moves up in the cylinder 18 and enters the compression stroke. As a result, the gas in the combustion chamber 26 is pushed by the piston 14 and attempts to flow backward from the combustion chamber 26 through the intake valve 32 to the upstream side through the intake valve 32. At this time, the intake flow path adjustment mechanism 42 operates as described above, and the intake passage 28 is almost closed.

  Then, the pressure on the downstream side of the intake flow path adjustment mechanism 42 increases, but as shown in FIG. 3, the air flow (air mixture) flows into the intake sub-passage 11, and the intake flow path adjustment mechanism 42 The one-way valve 13 is opened by the pressure on the downstream side, passes through the intake sub-passage 11, and flows out to the intake passage 28 on the upstream side of the intake flow path adjustment mechanism 42. As a result, the air pressed by the piston 14 flows out smoothly from the combustion chamber 26 even when the intake flow path adjustment mechanism 42 is closed, and pumping loss due to the piston 14 does not occur. The flow path restricting means is based on the measured pressure value downstream of the intake flow path adjusting mechanism 42, information on the operating state of the intake flow path adjusting mechanism 42 and the variable valve mechanism, piston position, and the like. It may be a valve that opens and closes. However, by using a check valve that opens and closes by receiving actual pressure, inexpensive and accurate control can be performed.

  FIG. 5 shows a change in the in-cylinder pressure in a state where the intake flow path adjustment mechanism 42 is operated. In FIG. 5, the horizontal axis is the in-cylinder (cylinder 18) volume, the vertical axis is the in-cylinder pressure, the bottom dead center of the piston 14 is located at the right end of the horizontal axis, and the top dead center is located near zero. is doing. A solid line C in FIG. 5 indicates a case where the intake sub-passage 11 is provided, and a dotted line D indicates a case where the intake sub-passage 11 is not provided. Thereby, when the piston 14 rises from the bottom dead center, the pressure in the dotted line D is higher than that in the solid line C. Thus, it can be seen that the pumping loss is smaller when the intake sub-passage 11 indicated by the solid line C is provided. Therefore, fuel consumption deterioration due to pumping loss can be prevented.

  Next, another example of the backflow adjusting means will be described.

  FIG. 6 shows an example in which a rotary valve 15 is provided in the intake sub-passage 11 instead of the one-way valve 13. The rotary valve 15 has a drive mechanism (not shown) similar to the intake flow path adjustment mechanism 42, and rotates the movable valve plate in the intake sub-path 11 to cause the intake sub-path 11 to move at a predetermined time. In other words, the downstream side is opened when the pressure rises from the upstream side. In this way, the backflow adjusting means may be configured.

  Furthermore, another example of the backflow adjusting means is shown in FIG. This is an example in which a reverse flow adjusting means is provided in the intake flow path adjusting mechanism 42. A movable valve plate 47 of the intake flow path adjusting mechanism 42 is rotatably attached to the support shaft 49 and is provided to be rotatable in the intake passage 28 by a drive mechanism. The opening cross-sectional area of the intake passage 28 can be reduced by rotating the movable valve plate 47 by the drive mechanism. The movable valve plate 47 is formed to be bent upstream by a rotating shaft 51 provided slightly above the support shaft 49, and the bent portion is a spring member or the like centering on the rotating shaft 51 ( It is urged to the downstream side with an appropriate spring force.

  According to this example, when the movable valve plate 47 is rotated, the opening cross-sectional area in the intake passage 28 is reduced in the same manner as described above, and as indicated by the solid line arrow, the flow velocity is increased in the vicinity of the injection hole of the fuel injection device 40. A fast air flow is formed. When the pressure on the downstream side from the upstream side of the intake passage 28 increases, the movable valve plate 47 bends against the spring force on the upstream side as indicated by a two-dot chain line, and the flow path of the intake passage 28 Enlarged to allow upstream air flow. Thereby, the pumping loss is not generated as described above, and the deterioration of fuel consumption can be prevented. Note that the movable valve plate 47 of FIG. 7 may not be bendable, but the intake passage 28 may be appropriately opened by a drive mechanism around the support shaft 49.

It is sectional drawing which shows one Embodiment of the internal combustion engine with a variable valve mechanism concerning this invention. It is sectional drawing which shows the intake passage of an internal combustion engine. It is sectional drawing which shows the intake passage of an internal combustion engine. It is a figure which shows the relationship between the valve opening degree of an intake / exhaust valve, and a crank angle. It is a figure which shows the relationship between the cylinder pressure of an internal combustion engine, and cylinder volume. It is sectional drawing which shows the intake passage provided with the other backflow adjustment means. It is sectional drawing which shows the intake passage provided with the other backflow adjustment means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Engine 11 ... Intake sub-passage 12 ... Cylinder head 13 ... One-way valve 14 ... Piston 15 ... Turning valve 18 ... Cylinder 26 ... Combustion chamber 28 ... Intake passage 32 ... Intake valve 36 ... Intake side valve mechanism 40 ... Fuel Injecting device 42 ... Intake flow path adjusting mechanism 43 ... Movable valve plate 45 ... Rotating shaft 49 ... Support shaft

Claims (5)

A cylinder,
A piston that is reciprocally movable in the cylinder;
A combustion chamber formed by the cylinder and the piston;
An intake passage communicating with the combustion chamber;
An intake passage adjustment mechanism for reducing an opening cross-sectional area of the intake passage;
In an internal combustion engine with
An internal combustion engine comprising reverse flow adjusting means for circulating gas downstream of the intake flow path adjustment mechanism from the downstream side to the upstream side of the intake flow path adjustment mechanism. The reverse flow adjusting means is provided in the intake passage, and an intake sub-passage that communicates the upstream side and the downstream side of the intake flow passage adjustment mechanism across the intake flow passage adjustment mechanism,
2. The internal combustion engine according to claim 1, wherein the internal combustion engine is formed by a flow path restriction unit that is provided in the intake sub-passage and permits only the flow from the downstream to the upstream of the intake sub-passage. The opening timing of the intake valve having an intake valve that opens and closes the opening at the opening of the intake passage facing the combustion chamber, and at least the intake valve can be opened until the middle of the compression stroke Equipped with a variable valve mechanism that can be changed,
When the intake valve adjusting mechanism reduces the opening cross-sectional area of the intake passage and the variable valve mechanism opens the intake valve until the middle of the compression stroke, the intake flow adjustment means 3. The internal combustion engine according to claim 2, wherein flow from the downstream side to the upstream side of the path adjustment mechanism is permitted.   4. The check valve according to claim 2, wherein the flow path restriction unit is a check valve that opens when the pressure on the downstream side of the intake flow path adjustment mechanism is higher than the pressure on the upstream side. 5. Internal combustion engine with variable valve mechanism. The intake flow path adjustment mechanism is provided in the intake passage, and includes a movable valve plate that operates so as to be able to close the opening cross section of the intake passage.
When the pressure on the combustion chamber side rises above the pressure on the upstream side of the intake flow path adjustment mechanism when a part of the movable valve plate sandwiches the intake flow path adjustment mechanism, the reverse flow adjustment means 2. The internal combustion engine with a variable valve mechanism according to claim 1, wherein the internal combustion engine is bent from the downstream side to the upstream side so as to open a part of the movable valve plate.

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