JPS6221980B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine intake system, and particularly to promoting atomization of fuel from a fuel supply body.

Conventionally, an engine intake system consists of a fuel supply body such as a carburetor or fuel injection valve, a butterfly-type throttle valve installed in the intake pipe, and an intake manifold that distributes a mixture of air and fuel to each cylinder. The main components are:

However, with such a configuration, there is a problem in that the distribution of the air-fuel mixture between the cylinders tends to be uneven, which tends to lead to deterioration in engine performance and an increase in harmful exhaust gas components. This is because the fuel supplied from a fuel supply body such as a carburetor adheres to the wall of the intake pipe and flows into each cylinder in the form of a liquid film, and this liquid film of fuel causes the air-fuel ratio of each cylinder to be uneven. This is because the fuel is not sufficiently atomized in the intake system.

In particular, in the case where the fuel injection valve is installed upstream of the throttle valve, the fuel injection pressure is quite high, so the fuel is sprayed regardless of the air flow, and as a result, the fuel is not uniformly injected into the intake pipe. However, there is a phenomenon in which the mixture ratio is large in areas where there is a large air flow (lean mixture), and is small in areas where there is little air flow (rich mixture), resulting in large variations in the mixture ratio between cylinders. A problem arises.

The present invention has been made in view of the above points, and includes a rectifier consisting of a heating element that generates heat when energized and has a large number of holes along the flow direction between the fuel supply body and the throttle valve in the intake pipe. Moreover, by arranging this rectifier to face the fuel supply body at a certain distance and having a gap around the entire circumference between the outer edge of the rectifier and the inside of the intake pipe, the The fuel is atomized by the air flow passing through the holes in the rectifier, and the liquid fuel adhering to the rectifier is also atomized by the heat generated by the rectifier. The fuel diffuses over the rectifier and reaches the outer edge, and is further actively atomized by the turbulence of the airflow passing through the gap between this outer edge and the inner wall of the intake pipe, resulting in good atomization. Since the fuel is mixed uniformly with the air heading toward the throttle valve, there is no possibility that the fuel will adhere to the wall of the intake pipe and form a liquid film, or that the ratio of the mixture may change due to the throttle valve. Therefore, a homogeneous mixture can be distributed equally to each cylinder of the engine.
In addition to improving engine performance, it is possible to prevent an increase in harmful exhaust gas components, and by providing a switch means that energizes the rectifier while the engine is warming up and shuts off when the engine is no longer warmed up. Only when the fuel atomization is poor, the rectifier generates heat to promote fuel atomization, and when the fuel atomization is good, the rectifier does not generate heat, thereby preventing unnecessary heating of the air-fuel mixture. The object of the present invention is to provide a useful engine intake system that does not cause volumetric expansion due to air-fuel mixture intake, resulting in a decrease in the amount of air-fuel mixture taken into the cylinders of the engine, and thus does not cause a decrease in engine output. be.

The present invention will be explained below with reference to embodiments shown in the drawings.
In FIG. 1, this device is configured to be applied to a spark ignition multi-cylinder engine used in automobiles, etc. The engine (not shown) has an air cleaner 1, an air flow meter 2, an intake pipe 3, as shown by arrows. , throttle valve 4 and intake manifold 5
Air or air-fuel mixture is inhaled through the air.

Here, the air flow meter 2 is of a known measuring plate type having a measuring plate whose opening degree changes depending on the air flow.
This changes the passage area of the variable fuel throttle 6.

Further, the throttle valve 4 is of a butterfly type rotatably supported by a shaft 7, and a link mechanism 8
The throttle valve 4 is connected to the accelerator pedal 9 of the automobile via the throttle valve 4, and the opening degree of the throttle valve 4 can be arbitrarily controlled by operating the accelerator pedal 9.

The intake manifold 5 is made of light alloy or the like, and guides the air-fuel mixture to each cylinder of the engine through passages 10, 11, etc. Further, a hot water type heat riser section 12 is integrally formed in the intake manifold 5, and has a structure for heating this.

A fuel injection valve 14 of an automatic outward opening type is installed at the upper part of the intake pipe 3, and this includes a fuel pump 1.
5. Fuel such as gasoline is supplied from a fuel system consisting of a fuel pressure regulator 16, a constant pressure differential valve 17, a fuel tank 18, and a variable fuel throttle 6.

Here, the fuel pump 15 is an electric type, and fuel at a constant pressure regulated by a regulator 16 is supplied to the variable fuel throttle 6. Constant differential pressure valve 1
Reference numeral 7 is for making the fuel pressure difference before and after the variable fuel throttle 6 constant, and operates so that the fuel flow rate is proportional to the passage area of the variable fuel throttle 6.

Since this passage area changes depending on the air flow meter 2, the fuel flow rate supplied to the fuel injection valve 14 is proportional to the air flow rate.

20 is a rectifier which forms the main part of the present invention;
As shown in the figure, the PTC ceramic is formed into a lattice shape with many holes 21 along the flow direction.
is formed. More specifically, it is made of barium titanate (BaTiO ₃ ), has a positive resistance R-temperature T characteristic as shown in FIG.
It has a Curie point near To, and when energized, the temperature rises to almost the Curie point temperature and generates heat.

This rectifier 20 is connected to the nozzle 1 of the fuel injection valve 14.
4a and the throttle valve 4,
The distance between the nozzle 14a and the rectifier 20 is preferably set to about 30 mm when the fuel injection valve 14 is a normal type, and about 20 mm when the fuel injection valve 14 is a spiral type.

A portion of the intake pipe 3 where the rectifier 20 is installed has a large diameter, and there is a gap 23 between the inner wall of the large diameter portion of the intake pipe 3 and the outer peripheral surface of the rectifier 20.
is formed.

The sum of the area of this gap 23 and the total area of the holes 21 of the rectifier 20 is set to be equal to the passage area of the throttle valve 4 when fully open.

An inclined surface 2 is provided between the large diameter portion and the small diameter portion of the intake pipe 3.
4 is formed, and this inclined surface 24 is inclined in the direction toward the center of the intake pipe 3, and this end portion protrudes into the pipe as a projection 25 over the entire inner circumference.

Next, the energizing circuit of the rectifier 20 will be explained. This includes a normally open relay 26, a ferrite water temperature switch 27, and an ignition key switch 28.
and a battery 29, and when the engine cooling water temperature is below 50°C with the key switch 28 turned on, the water temperature switch 27 is turned on and the relay 26 is turned on, thereby turning on the rectifier 20.
is energized.

Next, the installation structure of the rectifier 20 will be explained with reference to FIG. Here, the rectifier 20 has thin film-like platinum electrodes 20a and 20b attached to its upper and lower surfaces by a method such as chemical plating or paste baking.

Anode fixing member 30 and three cathode fixing members 3
1, 32, and 33 (of which 31 and 33 are shown in FIG. 2) are all made of carbon sintered bodies, and among these, the cathode fixing member, like the fixing member 32, is a typical example. Rectangular insulating plate 34 made of heat-resistant electrical insulating material such as glass epoxy resin
The rectifier 20 is supported via a rectangular metal plate 35 made of copper material. In other words, the insulating plate 34
is a metal plate 35 on the lower electrode 20b side of the rectifier 20.
is fixed to the fixing member 32 via a bolt 36 and a nut 37 in such a manner that it comes into contact with the upper surface electrode 20a side and holds the rectifier 20 therebetween.

This fixing member 32 passes through the intake pipe 3 and is fixed to the intake pipe 3 by an external screw 38. Of course, the other fixing members 31 and 33 also have the same structure as the fixing member 32. Note that due to the above structure, the electrode 20a
is grounded via the intake pipe 3.

On the other hand, a rectangular metal plate 39 made of a copper material and a rectangular insulating plate 40 made of a heat-resistant electrical insulating material such as glass epoxy resin are fixed to the anode fixing member 30 with bolts 41 and nuts 42. Of these, the metal plate 39 is connected to the electrode 20 of the rectifier 20.
b, the insulating plate 40 is in contact with the electrode 20 of the rectifier 20.
a, and the rectifier 20 is held between them.

The fixing member 30 is fixed via screws 44 to a fixing body 43 made of a heat-resistant electrical insulating material such as glass epoxy resin, which is press-fitted into the intake pipe 3 and fixed with adhesive. Note that a terminal 46 of a lead wire 45 is connected between the screw 44 and the fixed body 43, and this lead wire 45 is connected to the anode side of the battery 29.
In this way, the rectifier 20 is fixed to the intake pipe 3 via fixing members at four equal locations on its circumference.

In the above configuration, the operation will be explained. Close the key switch 28 and start the engine. During a cold start, the cooling water temperature is low, so the water temperature switch 27 is on, current flows through the coil of the relay 26, and the relay contact is turned on. As a result, the electrodes 20a and 20b of the rectifier 20 are energized, and the rectifier 20 generates heat.

On the other hand, when the driver of the automobile depresses the accelerator pedal 9, the throttle valve 4 opens, and the opening area between the throttle valve 4 and the intake pipe 3 increases. As a result, combustion air is drawn into the engine through the air cleat 1, the air flow meter 2, the intake pipe 3, and the intake manifold 5.

Then, fuel is supplied from the fuel injection valve 14 so as to generate an air-fuel mixture having an air-fuel ratio suitable for the operating condition of the engine with respect to this intake air flow rate. This fuel is injected toward the rectifier 20, which is provided at a constant distance from the fuel injection valve 14, and comes into contact with the rectifier 20. Most of the contacting fuel passes through the holes 21 of the rectifier 20, and the remaining part adheres to the grid wall of the rectifier 20.

Both types of fuel are finely atomized by the air flow passing through the partition walls, where the fuel and air are well mixed to produce a homogeneous air-fuel mixture. At this time, since the rectifier 20 is generating heat, it helps to further atomize the droplet fuel and creates a highly atomized or vaporized air-fuel mixture.

As can be seen from Fig. 2, the rectifier 20
Since a gap 23 is formed around the entire circumference between the outer edge of the rectifier 20 and the inner wall of the intake pipe 3, the fuel that cannot be sufficiently atomized by the holes 21 of the rectifier 20 flows into the rectifier 2.
The fuel diffuses over the rectifier 20 and reaches the outer edge, and is actively atomized by the turbulence of the high-speed airflow passing between the outer edge of the rectifier 20 and the inner wall of the intake pipe 3, so that the fuel does not remain on the rectifier 20. A very stable mixture can be created without any problems.

The obtained air-fuel mixture flows along the slope 24 of the intake pipe 3 and the slope of the protrusion 25 to be further mixed, and then collides with the throttle valve 4. When the air-fuel mixture spreads toward the outer circumference of the throttle valve 4 and separates from the end of the throttle valve 4, the air-fuel mixture is atomized very finely by the high-speed air flow that passes through the constriction between the throttle valve 4 and the intake pipe 3. The mixture becomes a homogeneous mixture and is inhaled into each cylinder of the engine.

As a result, the engine achieves high performance with a homogeneous air-fuel mixture, and harmful exhaust gas components such as HC are also reduced. Here, the gap between the fuel injection valve 14 and the rectifier 20 is always constant regardless of the operating state of the engine 1, and the distribution of the fuel supplied from the fuel injection valve 14 to the upper surface of the rectifier 20 is almost uniform. Therefore, the deflection distribution of the air-fuel mixture in the intake pipe 3 is easily eliminated.

Here, the rectifier 20 is sized so that the fuel spray from the fuel injection valve 14 covers the entire area, and the fuel injected onto the upper surface of the rectifier 20 is atomized from the hole 21 or the entire circumference of the outer edge of the rectifier 20. , since the atomized fuel flows toward the center of the intake pipe 3 along the slope 24 of the intake pipe 3 and the slope of the protrusion 25,
This also reduces the deflection distribution of the air-fuel mixture.
Furthermore, due to these, the amount of fuel adhering to the inner wall of the intake pipe 3 is extremely reduced, and the generation of liquid film fuel is reduced.

On the other hand, when the cooling water temperature rises and exceeds 50°C, that is, it is considered that it has left the warm-up state, the rectifier 2
Although current is no longer supplied between the electrodes 20a and 20b, the intake manifold 5 downstream of the throttle valve 4
The heat of the cooling water in the outer heat riser section 12 helps atomize the droplet fuel, making it possible to create a good air-fuel mixture. Incidentally, it goes without saying that the fuel injected from the injection valve is atomized by the rectifier 20 in the same way as when the cooling water temperature is low.

In FIG. 5, electrodes 20a and 20b are provided alternately, and electrodes 20a and 20b are provided even on the surface of the partition wall 20d of the rectifier 20.
This shows another embodiment in which 0a and 20b are extended. According to this example, the current flows through the partition wall 20d.
Since the current flows in the direction perpendicular to the rectifier 20, the resistance value of the rectifier 20 itself becomes small, and a large amount of heat generation can be obtained even at a low voltage.

FIG. 6 shows another embodiment of the present invention in which a substantially conical throttle valve 4 is provided so as to be movable up and down. Since it has a symmetrical structure, it is possible to better eliminate uneven distribution of the air-fuel mixture into the cylinders. In this embodiment, the injection valve is connected to the rectifier 2.
It is better to use a spiral system where the fuel is injected all over the 0.

Note that the present invention is not limited to the above embodiments, and can be modified in various ways.

(1) In each of the above embodiments, the rectifier 20 is made of PTC ceramic having a positive resistance temperature characteristic, but it does not need to be made of PTC ceramic as long as it is made of a heating element that generates heat when energized.

(2) Although the intake pipe 3 has a cylindrical shape, it can be changed as appropriate depending on the requirements of the engine.

(3) The fixing structure of the rectifier 20 is not limited to the structure shown in FIG. 4, and various structures can be considered.

(4) The intake manifold 5 may be heated with exhaust heat.

(5) Although the engine cooling water temperature is detected in order to control the energization to the rectifier 20, the engine lubricating oil temperature or the cylinder block temperature of the engine 1 may also be detected.

(6) The energization may be controlled by a timer device, assuming that the warm-up operation ends after a predetermined period of time after the engine 1 is started.

(7) Although the fuel supply body is configured with a fuel injection valve, it may also be a carburetor.

As described above, according to the present invention, the intake pipe includes a heating element that generates heat when energized and has a large number of holes facing the fuel supply body at a certain distance between the fuel supply body and the throttle valve. Since the rectifier is arranged and a gap is formed around the entire circumference between the outer edge of the rectifier and the inner wall of the intake pipe, the flow of fuel supplied from the fuel supply body is weakened by the rectifier, and the fuel flows inside the rectifier. At the same time, the liquid fuel adhering to the rectifier is also atomized by the air flow passing through the holes, and the liquid fuel that has adhered to the rectifier is also atomized by the heat generated by the rectifier. Atomization is further promoted by the airflow that passes through the gap when it diffuses over the rectifier, flows to the outer edge, and is separated from the outer edge, and the airflow also becomes a uniform flow through the rectifier, resulting in even better mixing. Also,
After that, it is mixed uniformly with the air heading towards the throttle valve, so unlike conventional fuel, the fuel adheres to the inner wall of the intake pipe and forms a liquid film, or the fuel and air are mixed depending on the opening degree of the throttle valve. There is almost no change in the ratio, and a uniformly mixed mixture can be distributed equally to each cylinder of the engine, which has the excellent effect of improving engine performance and reducing harmful exhaust gas components. .

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention;
Fig. 2 is a cross-sectional view taken along line AA in Fig. 1, Fig. 3 is a graph used to explain the operation, Fig. 4 is an enlarged sectional view of main parts showing the installation structure of the rectifier, and Fig. 5 is another embodiment of the rectifier. FIG. 6 is an enlarged sectional view of a main part showing another embodiment of the throttle valve. 3... Intake pipe, 4... Throttle valve, 5... Intake manifold, 14... Fuel injection valve forming a fuel supply body,
20... Rectifier, 21... Hole.

Claims (1)

[Scope of Claims] 1. A fuel supply body that supplies fuel into an intake pipe, an intake manifold that distributes an air-fuel mixture to each cylinder of the engine, and a fuel supply body that supplies fuel into the intake pipe from the fuel supply body to the intake manifold. a throttle valve provided in the intake pipe; and a plurality of holes located in the intake pipe between the fuel supply body and the throttle valve, provided facing the fuel supply body at a constant distance, and arranged along the flow direction. and a rectifier made of a heat generating element that generates heat when energized, and a gap is provided over the entire circumference between the outer edge of the rectifier and the inner wall of the intake pipe. 2. The engine intake system according to claim 1, wherein the rectifier made of the heating element that generates heat when energized is made of ceramic that has a positive resistance temperature characteristic and has a Curie point at a specific temperature.