JPH0343464B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an air intake device applied to an internal combustion engine.

(Background of the Invention) In conventional internal combustion engines, most of the intake passage that guides intake air to the intake valve is generally made of heat-resistant metal such as aluminum alloy. For example, in a gasoline injection multi-cylinder internal combustion engine, the surge tank, the throttle body connected upstream of the surge tank, the manifold that distributes intake air from the surge tank to each cylinder, etc. were all made of aluminum alloy and formed separately. Furthermore, in a multi-cylinder internal combustion engine using a carburetor, the carburetor body, intake preheating pipe, and manifold are all formed separately from aluminum alloy or the like.

On the other hand, in an internal combustion engine, intake air is intermittently drawn into the combustion chamber by opening and closing the intake valve, but when the intake valve opens, the flame inside the combustion chamber flows back into the intake passage, causing what is called backfire. may occur.

Therefore, conventional intake passages use metal that does not change or deteriorate due to flames during backfire, but this has the disadvantage of increasing the weight of the engine. Furthermore, in order to reduce the weight, it is possible to use synthetic resins that are resistant to flames, but such synthetic resins are expensive and difficult to use in large quantities in the intake system.

In order to prevent this backfire, some engines have a wire mesh installed in the middle of the intake passage. In order to increase the amount of synthetic resin used here, if a wire mesh is installed downstream of the carburetor and near the cylinder head, all the air-fuel mixture will pass through this wire mesh, so fuel will be captured by this wire mesh, especially at low speeds. However, there was a problem in that the concentration of the air-fuel mixture sucked into the combustion chamber became uneven, resulting in unstable operation at low speeds.

(Objective of the Invention) The present invention was made in view of the above circumstances, and it is possible to significantly reduce the weight of the intake passage by using a large amount of relatively inexpensive synthetic resin, and also to make it possible to significantly reduce the weight of the intake passage. Therefore, even though a wire mesh is placed close to the cylinder head to prevent backfire, the concentration of the air-fuel mixture supplied to the combustion chamber remains stable, making this internal combustion engine suitable for stabilizing operation, especially at low speeds. The purpose of this invention is to provide an intake device for the following.

(Structure of the Invention) According to the present invention, this object is achieved by an internal combustion engine in which intake air introduced into an intake passage 44 is intermittently drawn into a combustion chamber via an intake valve 18. a wire mesh 52 provided so as to cross the intake passage 44 near the connection between the resin intake pipe 30 and the cylinder head 16;
and the intake passage 4 on the cylinder head 16 side.
This is achieved by an intake system for an internal combustion engine characterized by comprising a fuel injection valve 46 for injecting fuel into the internal combustion engine.

This same purpose is achieved by the cylinder head 1 in an internal combustion engine in which intake air guided into the intake passage 68 is intermittently drawn into the combustion chamber via the intake valve 18.
a wire mesh 84 provided to cross the intake passage 68 in the vicinity of the connection between the synthetic resin intake pipe 30 connected to the cylinder head 16 and the cylinder head 16; a sub-throttle valve 78 provided between the fuel supply means 60 and the wire mesh 84; and a sub-intake passage 80 that bypasses the sub-throttle valve 78 and the wire mesh 84. This is achieved by an intake system for an internal combustion engine characterized by comprising:

(Embodiment) FIG. 1 is a cross-sectional view showing an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line -- in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line -- in FIG. In this embodiment, the present invention is applied to a gasoline injection type multi-cylinder internal combustion engine. In FIG. 1, reference numeral 10 is the engine body. This main body 10 includes a cylinder body 12, a piston 14, and a cylinder head 1.
6, an intake valve 18, an exhaust valve 20, a cylinder head cover 22, and a spark plug 24. Intake valve 18
The exhaust valve 20 is opened and closed at predetermined timing by a known valve operating mechanism housed within the cylinder head cover 22. An exhaust pipe 26 is connected to the cylinder head 16, and an exhaust passage 28 communicating with the exhaust valve 20 is formed in the exhaust pipe 26 and the cylinder head 16.

30 is an intake pipe. This intake pipe 30 can be made of synthetic resin such as 66 nylon or 66 nylon mixed with glass fiber. A surge tank section 32, a manifold section 34, and a throttle body section 36 are integrally formed in the intake pipe 30. The manifold part 34 is
It is located between the surge tank section 32 and the cylinder head 16, and communicates the intake valve 18 of each cylinder with the surge tank section 32. Throttle body part 36
is located upstream of the surge tank section 32, and the throttle body section 36 is provided with a throttle valve 38. 40 is an air flow meter that detects the intake flow rate, and 42 is an air duct that communicates the air flow meter 40 with the throttle body portion 36. These air flow meters 40, ducts 4
2. The intake pipe 30 and the cylinder head 16 form an intake passage 44 that guides intake air to the intake valve 18. 46 is a fuel injection valve, and 48 is a delivery pipe. The fuel injection valve 46 is attached to the manifold portion 34 of the intake pipe 30 so as to face the direction of the intake valve 18, and opens based on an electric signal output from a control device (not shown) to increase pressure in the delivery pipe 48. The fuel is injected from the downstream side of the wire mesh 52, which will be described later, toward the intake valve 18 and into the intake passage 44 on the cylinder head 16 side.

The inner surface of the manifold part 34 is the cylinder head 1
The diameter of the opening on the side 6 is expanded, and the metal cylindrical member 3 is inserted here.
5 is fitted and fixed. One opening edge of this cylindrical member 35 is bent inward into a flange shape to form a stepped portion 50 as shown in FIG. A wire mesh 52 is attached to this stepped portion 50 so as to cross the entire opening of the intake passage 44 . In other words, wire mesh 5
2 is sandwiched between two annular metal fittings 54 and 56 having an L-shaped cross section, and these annular metal fittings 54 and 56 are connected to a stepped portion 50 and a circlip 58 attached to the inner surface of the opening side of the manifold portion 34. held between. In this way, the wire mesh 52 is provided so as to cross the intake passage 44 in the vicinity of the connection between the intake pipe 30 and the cylinder head 16, and the wire mesh 52
The inner surface of the intake passage 44 on the downstream side is entirely made of metal.

Next, the operation of this embodiment will be explained. When the intake valve 18 opens during the intake stroke, an amount of intake air corresponding to the opening degree of the throttle valve 38 is drawn into the combustion chamber.
The amount of intake air is detected by an air flow meter 40,
The control device opens the fuel injection valve 46 for an appropriate amount of time based on the intake air amount, the opening degree of the throttle valve 38, and other signals indicating the operating state. Fuel pressurized to a predetermined pressure is supplied to the delivery pipe 48, and the fuel in the delivery pipe 48 is injected into the intake passage 44 when the fuel injection valve 46 is opened. Since the wire mesh 52 is located upstream of the fuel injection valve 46, the injected fuel is not captured by the wire mesh 52, and the entire amount thereof smoothly flows into the combustion chamber together with the intake air.

Also, the fuel is supplied to the intake passage 4 on the cylinder head 16 side.
Since the fuel is injected into the combustion chamber 4, the fuel hardly adheres to the inner wall of the intake passage 44 and is immediately drawn into the combustion chamber. Therefore, the responsiveness of mixture concentration control is very good.

When the intake valve 18 closes and a compression stroke occurs, an electric spark hits the ignition plug 24, igniting the air-fuel mixture in the combustion chamber, resulting in an explosion stroke. When the exhaust valve 20 opens at the end of the explosion stroke, burnt gas is discharged to the exhaust passage 28, but since the intake valve 18 starts to open in the middle of the exhaust stroke, depending on the operating condition, high-temperature burnt gas may be discharged. Gas or gas being combusted may flow back from the intake valve 18 to the intake passage 44 (backfire). However, since the intake passage 44 is provided with a wire mesh 52, the flame flowing backward is cooled and extinguished by the wire mesh 52. That is, since the wire mesh 52 is disposed on the downstream side of the intake pipe 30 made of synthetic resin, flames caused by backfire are blocked by the wire mesh 52 and do not enter the upstream side. Therefore, the intake pipe 30 made of synthetic resin is not directly exposed to flames and is not subject to alteration or deterioration due to flames.

In this embodiment, the manifold section 34, surge tank section 32, and throttle body section 36 are integrally formed of synthetic resin, which reduces the number of parts and makes assembly easier.
6 may be formed separately and joined to each other. It is also possible to form only a portion of the intake pipe 30 from synthetic resin.

FIG. 4 is a cross-sectional view of an embodiment in which the present invention is applied to an internal combustion engine using a carburetor, FIG. 5 is a cross-sectional view taken along the - line, and FIG. In FIG. 4, 60 is a downdraft compound vaporizer, 62 is a heat insulator, 64 is an intake air heating pipe, and 66 is a manifold, which are connected in sequence to an intake passage 68 that communicates with the intake valve 18.
form. The body of the carburetor 60 is made of synthetic resin, and a choke valve 70 and a primary throttle valve 72 are provided on the primary side 60A, and a primary throttle valve 72 is provided on the secondary side 60A.
B is a secondary throttle valve 7 that responds to intake negative pressure.
4 are arranged. The intake air heating pipe 64 has a water passage 7.
6 is formed, and cooling water for the engine circulates in this waterway 76. Therefore, the fuel mixed into the intake air in the carburetor 60 is heated by the intake air heating pipe 64, and its vaporization is promoted.

A sub-throttle valve 78 is provided on the manifold 66, and the sub-throttle valve 78 opens with a delay from the primary throttle valve 72. 80 is a sub-throttle valve 78 and a wire mesh 84
This is a sub-intake passage that bypasses the This sub-intake passage 8
0 has a cross section smaller than the intake passage 68, one end of which opens on the inner lower surface of the manifold 66 upstream of the sub-throttle valve 78, and the other end of which is directed diagonally into the combustion chamber from the intake passage 68 in the cylinder head 16. Open as shown.

82 is the manifold 66 and cylinder head 16
It is a gasket sandwiched between the A wire mesh 84 is fixed to this gasket 82 so as to traverse the entire surface of the intake passage 68. That is, as shown in FIG. 6, two annular members 86 and 88 having approximately the same diameter as the intake passage 68 are attached to this gasket 82, and a wire mesh 84 is inserted between these annular members 86 and 88.
is being held. Therefore, when the manifold 66 is attached to the cylinder head 16 via this gasket 82, the wire mesh 84 will be positioned to cross the intake passage 68. As a result, the intake passage 6
8, the downstream inner surface of the wire mesh 84 is made of metal. In FIG. 4, the same parts as in FIG. 1 are given the same reference numerals, so their description will not be repeated.

Next, the operation of this embodiment will be explained. During low load operation, the opening degree of the primary throttle valve 72 is small;
Therefore, the sub-throttle valve 78 is closed. Therefore, the intake air mainly passes through the auxiliary intake passage 80 and the intake valve 1
When valve 8 is opened, it is sucked into the combustion chamber at high speed and generates a strong swirl. As a result, the entire amount of fuel droplets contained in the air-fuel mixture is sucked into the combustion chamber without being captured by the wire mesh 84, promoting combustion at low loads.

During high load operation, as the opening degree of the primary throttle valve 72 increases, the auxiliary throttle valve 78 also opens with a delay. Therefore, the amount of intake air flowing through the sub-intake passage 80 decreases, and the intake air flows through the intake passage 6 with a large cross-sectional area.
8 into the combustion chamber. Therefore, the intake resistance during high loads can be reduced. Further, the secondary throttle valve 74 automatically begins to open when the intake negative pressure becomes greater than a predetermined value (away from atmospheric pressure) to compensate for the shortage of intake air amount.

When the intake valve 18 begins to open, high-temperature burnt gas or gas being combusted from the combustion chamber flows back into the intake passage 68, potentially causing backfire. However, since a wire mesh 84 is disposed between the cylinder head 16 and the manifold 66, the flame is
It is cooled and extinguished by 4.

(Effects of the Invention) As described above, the invention as set forth in claim 1 provides a method in which a wire mesh is provided to cross the intake passage in the vicinity of the connection between the cylinder head and the synthetic resin intake pipe. Since a fuel injection valve is installed to inject fuel into the intake passage inside the combustion chamber, even if high-temperature gas or burning gas inside the combustion chamber flows back into the intake passage, the flame will be blocked by this wire mesh. Therefore, the flame does not come into direct contact with the synthetic resin intake passage located upstream of the wire mesh, and the synthetic resin is not altered or deteriorated by the flame. In other words, it is not necessary to use an expensive synthetic resin that is resistant to flames, and it becomes possible to use an inexpensive and lightweight synthetic resin. In particular, since the wire mesh is close to the cylinder head, the synthetic resin part on the upstream side becomes longer, making it possible to significantly reduce the weight of the intake system.

Further, since the fuel is supplied into the cylinder head on the downstream side of the wire mesh, the fuel is guided into the combustion chamber without being captured by the wire mesh at all, and with almost no adhesion to the inner wall of the intake passage. Therefore, the fuel supplied from the fuel injection valve enters the combustion chamber as it is, allowing operation at the optimum mixture concentration for each combustion cycle, and stabilizing engine rotation.

Further, according to the invention described in claim 2, a sub-throttle valve is provided on the upstream side of a wire gauze provided near the joint between the synthetic resin intake pipe and the cylinder head, and the wire gauze and the sub-throttle valve are connected to each other. Since the auxiliary intake passage is provided by bypassing the wire mesh, the synthetic resin intake pipe portion upstream of the wire mesh is lengthened, and the intake system is made cheaper and lighter in the same manner as the invention of item 1 above. be able to. Further, a portion of the fuel bypasses the wire mesh, is guided from the auxiliary intake passage to the cylinder head side intake passage, and is immediately supplied to the combustion chamber. Especially when driving at low speeds, the auxiliary throttle valve closes, so almost all intake air is supplied from this auxiliary intake passage.
Fuel is guided into the combustion chamber without being trapped by the wire mesh or the inner wall of the intake passage. Therefore, the same effect can be obtained by sharing the main parts of the structure with the invention of claim 1 above.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of one embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the - line, FIG. 3 is a cross-sectional view taken along the line - in FIG. 2, and FIG. 4 is a cross-sectional view of another embodiment.
FIG. 5 is a sectional view taken along the - line, and FIG. 6 is a sectional view taken along the - line in FIG. 16...Cylinder head, 18...Intake valve, 44,
68...Intake passage, 46...Fuel injection valve, 52, 84
... wire mesh, 60 ... carburetor as fuel supply means, 8
0...Sub-intake passage.

Claims (1)

[Claims] 1. The intake air guided to the intake passage 44 is transferred to the intake valve 18.
In an internal combustion engine that intermittently draws air into the combustion chamber through a cylinder head 16, a synthetic resin intake pipe 30 connected to the cylinder head 16 is provided so as to cross the intake passage 44 in the vicinity of the connection between the cylinder head 16 and the cylinder head 16. a metal mesh 52 that is attached to the cylinder head 16, and a fuel injection valve 4 that injects fuel into the intake passage 44 on the cylinder head 16 side.
6. An intake system for an internal combustion engine, comprising: 2. The intake air guided to the intake passage 68 is passed through the intake valve 18.
In an internal combustion engine that intermittently draws air into the combustion chamber through a cylinder head 16, a synthetic resin intake pipe 30 connected to the cylinder head 16 is provided so as to cross the intake passage 68 near the connection point between the cylinder head 16 and the cylinder head 16. a wire gauze 84 , and a fuel supply means 6 for supplying fuel into the intake passage 68 upstream of the wire gauze 84 .
0, a sub-throttle valve 78 provided between the fuel supply means 60 and the wire mesh 84, and a sub-intake passage 80 that bypasses the sub-throttle valve 78 and the wire mesh 84. intake device.