JPH028137B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention improves the distribution of air-fuel mixture to each cylinder of a multi-cylinder internal combustion engine, and heats only the primary side passage of a multiple intake system. The present invention relates to an intake system for an internal combustion engine that is designed to improve ignition performance and increase combustion temperature in a low load range without reducing volumetric efficiency in a high load range, thereby producing high output.

(Prior art) In a multi-cylinder internal combustion engine that uses only one carburetor and distributes a uniform air-fuel mixture to each cylinder with this one carburetor, it is difficult to achieve good distribution between each cylinder. There is a need to. For this reason, conventional techniques that have been commonly used include changing the shape of the intake manifold so that the air-fuel mixture flows evenly and smoothly to each cylinder, and each branch passage of the intake manifold (distribution This was dealt with by balancing the pressure within the air-fuel mixture (passage) or by improving the atomization of the air-fuel mixture.

(Problem to be solved by the invention) However, solving the shape of the intake manifold involves various constraints such as rigging, manufacturing, and performance, and it is difficult to ensure uniform air-fuel mixture distribution over the entire operating range. is quite difficult. In addition, in order to equalize the pressure within each branch passage of the intake manifold, it has been considered to change the cross-sectional area and length of each branch passage, but it is not possible to obtain good results in terms of performance. Furthermore, there is a method of heating the intake manifold in order to promote fuel vaporization, but this method is not yet sufficient.

Particularly in operating regions where the air-fuel mixture flow rate is slow,
Since the flow of the air-fuel mixture tends to become a wall flow, fuel tends to adhere to the wall surface due to the roughness of the inner surface of the intake manifold.For this reason, the inner surface of the intake manifold is made as smooth as possible, but due to its complicated shape. However, there are limits to the ability to finish smooth surfaces.

The present invention has been made in view of the above circumstances, and in particular, takes drastic measures to promote atomization of the air-fuel mixture, and incidentally takes the above-mentioned measures as appropriate. Improves the distribution of the air-fuel mixture to each cylinder, and at the same time heats only the primary passage of the dual intake system, improving ignition performance in low load ranges without reducing volumetric efficiency in high load ranges. An object of the present invention is to provide an intake device for an internal combustion engine that increases combustion speed and produces high output.

(Means for Solving the Problems) As a means for solving the above problems, the present invention divides the fuel system from the carburetor 6 to just before the intake valve 5 into a primary fuel system and a secondary fuel system. In an intake system formed with separate dual intake passages,
For the intake passage 11 of the primary side fuel system, a distribution passage 81 is formed which is branched to communicate with each cylinder, and an intake passage of the secondary side fuel system is branched at a position directly downstream of the carburetor 6. 10 is provided with an adapter 8 having an intake passage 12 with a number of holes corresponding to each cylinder after branching.
is interposed immediately before the intake valve 5, and the distribution passage 81 in the primary side fuel system of the adapter 8 is
and the carburetor 6 through a primary side intake passage 9 consisting of one passage, and the adapter 8
Intake passage 12 corresponding to each cylinder of the secondary side fuel system of
is formed in a passage communicating with the secondary side intake passage 10 from the carburetor 6 to just before the intake valve 5, and on the side of the primary side intake passage 9 and the distribution passage 81 in the adapter 8, A cooling water jacket 13 is provided for heating both passages, and only the primary fuel system is heated by the engine cooling water flowing through the cooling water jacket 13.

In an engine having an intake system configured in this manner, the throttle valves 25 and 38 can theoretically be provided anywhere from the carburetor 6 to just before the intake valve 5, but due to manufacturing considerations. Due to the problem, one throttle valve 25 on the primary side is provided in the carburetor 6, and three throttle valves 38 on the secondary side are provided in the adapter 8, which is easy to manufacture, and these three are interlocked. It is better to do so.

(Function) By having the above configuration, the present invention has the following features:
Since only the primary side passage of the dual intake system is heated, it is possible to improve ignition performance and combustion speed in the low load range without reducing volumetric efficiency in the high load range. This means that the output can be demonstrated. Also, due to its configuration, the complex-shaped intake manifold 7 does not have to be directly processed.
The distribution passage 81 communicating with each cylinder can be formed linearly by machining in the adapter 8, which can have a simple shape, and its inner surface can be finished extremely smooth.

Furthermore, in accordance with this, a cooling water jacket (cooling water jacket 1 in the intake manifold 7) for heating the distribution passage 81 is installed in the adapter 8.
3 and the cooling water jacket 8 in the adapter 8
3) to further promote the atomization of the air-fuel mixture, especially in the distribution passage 81.
The fact that the distribution passage 81 and the cooling water jackets 13, 83 can be formed by machining means that the partition wall between the distribution passage 81 and the cooling water jackets 13, 83 can be made as thin as possible, which improves the heat transfer between them and improves the air-fuel mixture. This is preferable in terms of atomization.

(Example) An example of the present invention will be described below with reference to the drawings. In Fig. 1, 1 is the cylinder head, 2
is a combustion chamber, 3 is a secondary intake port formed in the cylinder head 1, 4 is a primary intake port that communicates with the intake port 3 in the middle, and 5 opens and closes the intake port 3 to the combustion chamber 2. An intake valve, at least an intake port 4 on the primary side, is oriented toward the combustion chamber 2 so as to generate a swirl of intake air in the combustion chamber 2.

In Figure 1, 6 is a carburetor, 7 is an intake manifold,
8 is an adapter. This adapter 8 is manufactured separately from the intake manifold 7, and is an important component of the present invention. Details will be described later. In the figure, 9 is the intake passage on the primary side in the intake manifold 7, 10 is the intake passage on the secondary side in the intake manifold, 11 is the intake passage on the primary side in the adapter 8, and 12 is the secondary side in the adapter 8. 13 is an in-manifold cooling water jacket formed in the intake manifold 7, 14 is a wall that partitions the intake passage 9 and the manifold cooling water jacket 13, and 15 is directed into the manifold cooling water jacket 13. These are heat transfer fins provided on the wall 14. As shown in the figure, the intake passage 10 on the secondary side
is branched for each cylinder within the intake manifold 7 connected immediately downstream of the carburetor 6.

16 is a float chamber of the carburetor 6. This carburetor 6 is a dual system having a primary side fuel supply system and a secondary side fuel supply system, of which the primary side fuel supply system is the main fuel supply system on the primary side and the primary side fuel supply system. It has a slow fuel supply system. This main fuel supply system on the primary side includes a bench lily 17 and a main nozzle 18 disposed within this bench lily 17.
, a fuel well 19 that communicates the main nozzle 18 with the bottom of the float chamber 16 , a main jet 20 provided on the float chamber 16 side of the fuel well 19 , and a passage 6 a of the main nozzle 18 on the air cleaner side. The main air jet 22 has a passage 21 communicating with the main air jet 21 and a main air jet 22 provided within the passage 21.

In the figure, 23 is a chiyoke valve provided upstream of the main nozzle 18, and 24 is a main nozzle 18.
The downstream intake passage 25 is a primary-side throttle valve mounted within the intake passage 24. Although the throttle valve 25 may be functionally provided further downstream, it is provided at this general position. The slow fuel supply system on the primary side includes a bypass port 26 that opens immediately upstream of the throttle valve 25, an idle port 27 that opens immediately downstream of the throttle valve 25, and a passage 21 that communicates with the fuel well 19 and the passage 6a. , slow jet 2 provided in the middle of this passage 21
8, a passage 29 which connects the slow air jet 22 provided on the passage 6a side of the passage 21 with the bypass port 26 and the idle port 27 with the passage 21, and the idle port 2.
It has a screw 30 that adjusts the opening degree of 7. Note that the intake passageway on the primary side consisting of the intake passages 24, 9, and 11 and the intake port 4 is connected to the bench lily 1.
7 and the intake port 3 are communicated with each other.

The secondary fuel supply system also includes a secondary main fuel supply system and a secondary slow fuel supply system. The main fuel supply system on the secondary side is a bench lily 31,
A main nozzle 32 disposed within this bench lily 31, a fuel well 33 that communicates the main nozzle 32 with the bottom of the float chamber 16, and a main jet 34 provided on the float chamber 16 side of this fuel well 33. , a main jet 34 provided in the main nozzle, a passage 35 communicating the main nozzle 32 with the passage 6b upstream of the bench lily, and a main air jet 36 provided in the passage 35. In the figure, 37 is an intake passage downstream of the main nozzle 36, and 38 is a secondary throttle valve installed in the intake passage 12 of the adapter 8. This throttle valve 38
Although theoretically it may be provided upstream of the adapter 8, it is provided within the adapter 8 from a manufacturing standpoint.

The slow fuel supply system on the secondary side includes a bypass port 39 that opens immediately upstream of the throttle valve 38.
, an idle port 40 that opens directly downstream of the throttle valve 38 , a passage 41 that communicates these with the passage 6 b , and this passage 4 .
1, a passage 43 communicating the fuel well 33 and the passage 41, and a slow jet 43a provided in the passage 43. It should be noted that a secondary-side intake air conduit including the intake passages 37, 10, 12 and the intake port 3 communicates the vent lily 31 with the combustion chamber 2.

In the figure, 44 is an exhaust suction port of the adapter 8 that communicates with the idle port 40, and 45 is the port 4.
A passage 46 connecting the passage 4 and an exhaust passage (not shown) is an EGR valve interposed in the middle of the passage 45. Also, 47 is the throttle valve 25
48 is a shaft supporting the throttle valve 38; 49 is a shaft supporting the throttle valve 38;
is a lever fixed to the throttle shaft 47,
A wire 50 connects the lever 49 to an accelerator pedal (not shown).

The throttle valve 38 on the secondary side is opened and closed by a valve operating device that utilizes intake negative pressure, and its opening degree is limited by a link mechanism linked to the throttle valve on the primary side. This valve operating device and link mechanism will be described in detail below.

In this embodiment, an actuator 51 is used as the valve operating device. This actuator 5
1 includes a main body 52, a lid 53 fitted to the main body 52, a diaphragm 54 held between the main body 52 and the lid 53, a rod 55 supported by the diaphragm 54, and a diaphragm 54. Compression coil spring 5 interposed between lid body 53
6. In the figure, A is a negative pressure introduction chamber formed between the lid 53 and the diaphragm 54, and B is an atmosphere open chamber formed between the diaphragm 54 and the main body 52.

The rod 55 of the actuator 51 like this
is pivotally attached to the tip of a lever 57 that is integrally fixed to the throttle shaft 48. Also, 58
59 is a primary side negative pressure intake opening in the bench lily 17, and 59 is a secondary side negative pressure intake opening in the bench lily 31. This negative pressure intake port 58 is connected to the passage 6
0, 61 and orifices 62, 63 to the negative pressure introduction chamber A, and the negative pressure intake port 59 communicates with the passages 60, 6.
4 and the negative pressure introduction chamber A through the orifices 60 and 65.
is connected to. And the actuator 51 is
It is set to open the throttle valve 38 on the secondary side by operating with the pressure acting on the negative pressure intake port 58 when the throttle valve 25 on the primary side is fully opened.

The link mechanism described above is connected to the throttle shaft 4.
The lever 66 attached to 7, the lever part 67a,
67b, and the throttle shaft 48
A lever 67 rotatably supported by the lever 67, a bent portion 68 integrally provided on the lever portion 67a, and a rod 69 connecting the lever 66 and the lever portion 67b.
has.

Reference numeral 70 denotes a limit pin protruding from the end of the lever 57, and the limit pin 70 rotates together with the lever 57 as the lever 57 rotates clockwise, so that it can come into contact with the bent portion 68. is set to . Further, on the upstream side of the secondary side bench lily 31, a variable valve 71 is installed which opens and closes depending on the internal intake negative pressure. This variable valve 71 includes a protrusion 72 of the carburetor 6 and a lid 7 attached to the protrusion 72.
3, a diaphragm 74 held between the protrusion 72 and the lid 73, and the protrusion 7 provided in the passage 6b.
5, a piston valve 76 supported by a diaphragm 74 and held movably back and forth with respect to a protrusion 75, and a compression coil spring 77 interposed between the lid body 73 and the diaphragm 74. An atmosphere open chamber C is formed between the protrusion 75 and the diaphragm 74, and the diaphragm 74
A negative pressure introduction chamber D is formed between and the lid body 73. This atmosphere opening chamber C communicates with the air cleaner side via a passage 78 of the carburetor 6, and the negative pressure introduction chamber D communicates between the piston valve 76 and the protrusion 75 via a hole 79 formed in the piston valve 76. It communicates with the variable bench lily 80.

The aforementioned adapter 8 is interposed between the cylinder head 1 and the intake manifold 7 as shown in FIG. 1, and is inserted into the engine in the arrangement direction of each cylinder of the engine as shown in FIG. It is a horizontally long plate-like object that extends almost parallel. The distribution passage 81 in the primary side fuel system of this adapter 8 and the carburetor 6 are communicated through a primary side intake passage 9 consisting of one passage. As shown in FIGS. 4 and 5, this adapter 8 includes an intake passage 9 on the primary side.
An intake passage 11 consisting of one hole communicating with the secondary side intake passage 10 and an intake passage 12 consisting of three holes communicating with the secondary side intake passage 10 are provided. It does not penetrate directly into the
It communicates with the intake passage 4 via a branching passage 81 provided inside in the longitudinal direction.

As a result, in the primary fuel system, the intake passage 9 in the intake manifold 7 reaches the intake port 4 corresponding to each cylinder via the distribution passage 81 in the adapter 8, and the intake port 4 (in this embodiment 3 pieces)
(See the portion indicated by reference numeral 4 in FIG. 3 and FIG. 5).

On the other hand, the secondary side fuel system is connected to the lower part of the carburetor 6 (first
6A in the figure), it is branched into the intake passage 10 for each cylinder as shown in Figure 3 (this example is a three-cylinder engine, so it is branched into three), and is After that, the intake passage 12 for each cylinder provided in the adapter 8 (see Fig. 4)
, and then reaches the upstream portion of the intake valve 5 via the intake port 3 .

In this way, the primary fuel system is branched into the intake ports 4 for each cylinder within the adapter 8, which is installed between the intake manifold 7 and the cylinder head 1, just before the intake valve 5. The next fuel system is branched for each cylinder at the bottom of the carburetor 6, and downstream from it is a dedicated intake passage 1.
0 and 12 to reach the intake passage 3.
Note that the distribution passage 81 of the adapter 8 can be provided in the longitudinal direction of the plate-shaped adapter 8 by machining, for example, by drilling. Distribution passage 81
When processed in this way, use adapter 8.
Since there are holes at both ends, these holes are plugged with blind plugs 82.

The inside of the adapter 8 has approximately the same length as the length of the distribution passage 81, extends in the longitudinal direction of the adapter 8 along this distribution passage 81, and
An adapter cooling water jacket 83 is provided that passes through the adapter 8. This in-adapter cooling water jacket 83 is connected to one end of the adapter 8 (the third
It communicates with the cooling water jacket 1a of the cylinder head 1 at a portion indicated by the symbol X in the figure, so that the engine cooling water after cooling the cylinder head 1 is introduced. At the other end (the part indicated by the symbol Y in FIG. 3), the cooling water passes through a thermostat 84 of a well-known structure that controls the circulation of cooling water, and is led to a radiator (not shown) as indicated by an arrow Y. There is.

As mentioned above, the manifold cooling water jacket 13 is formed in the intake manifold 7, and the engine cooling water after cooling the cylinder head 1 is introduced and heats the wall 14 through the fins 15. It's summery. This manifold cooling water jacket 13 communicates with the adapter cooling water jacket 83 at two parts (not shown), and after cooling the cylinder head 1, part of the cooling water flowing through the adapter cooling water jacket 83 is connected to the adapter cooling water jacket 83. It is starting to be introduced. The engine cooling water cooled by the radiator is circulated again from the direction of arrow X to the adapter cooling water jacket 83. Note that the reference numeral 85 in FIG. 1 is a bypass hole.

Next, to explain the operation of this intake system configured as described above, in a relatively low-load operating range when the secondary throttle valve 38 is closed, the primary throttle valve 25 The air-fuel mixture that has passed through is introduced into the distribution passage 81 in the adapter 8 while being heated in the primary intake passage 9 in the intake manifold 7, where it is distributed and then introduced into the combustion chamber 2 of each cylinder. It will be destroyed. This distribution passage 81
is located near the combustion chamber 2 as described above, and has a smooth inner surface, and
The air-fuel mixture is reheated by the engine cooling water flowing inside the adapter cooling water jacket 83, so that the mixture is sufficiently atomized and evenly distributed to the combustion chamber 2 of each cylinder without liquid fuel adhering to the wall surface. Ru.

In this case, by providing the variable bench lily 80 upstream of the secondary side bench lily 31, temporary dilution of the air-fuel mixture at the initial stage of opening of the secondary side throttle valve 38 can be prevented. is not directly related to the present invention,
The details are omitted.

(Effects of the Invention) Since the present invention is an intake system for an internal combustion engine configured as described above, it is possible to improve the distribution to each cylinder, and also to improve the distribution performance for each cylinder. By heating only the intake passage, it is possible to improve ignition performance and increase combustion speed in low load ranges, without reducing volumetric efficiency in high load ranges, and to achieve high output. become. The structure that heats the primary side intake passage is heated at the gathering part of the primary side intake passage, and then distributed to each cylinder using an adapter, so there is no need to provide a long heating passage, and the intake passage Since the primary and secondary intake passages are separated until just before the valve, there is also the advantage that the secondary intake passage is not preheated, improving volumetric efficiency.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG.
3 is a plan view of the carburetor shown in FIG. 1, FIG. 3 is an overall plan view of the internal combustion engine according to the present invention, and FIG. 4 is a plan view of the carburetor shown in FIG.
FIG. 5 is a front view of the adapter seen from the intake valve side in the figure, and FIG. 5 is a sectional view taken along the line - in FIG. 4. 1... Cylinder head, 2... Combustion chamber, 3...
Secondary side intake port, 4... Primary side intake port, 5... Intake valve, 6... Carburetor, 7... Intake manifold, 8... Adapter, 9, 11...
Intake passage on the primary side, 10, 12... Intake passage on the secondary side, 13... Cooling water jacket in the manifold, 81... Distribution passage, 83... Cooling water jacket in the adapter.

Claims (1)

[Claims] 1 Separate the fuel system from the carburetor to just before the intake valve into a primary fuel system and a secondary fuel system,
In an intake system formed with dual intake passages, a distribution passage is formed for the intake passage of the primary side fuel system that is branched to each cylinder and communicates with the cylinder, and a distribution passage that is branched to communicate with each cylinder is formed, and a distribution passage that is branched to communicate with each cylinder is formed for the intake passage of the primary side fuel system. For the intake passage of the next side fuel system, an adapter having an intake passage consisting of the number of holes corresponding to each cylinder after branching is provided, and the adapter is interposed immediately before the intake valve, and the The distribution passage in the primary side fuel system and the carburetor are communicated through the primary side intake passage consisting of one passage, and the intake passage corresponding to each cylinder of the secondary side fuel system of the adapter is connected to the carburetor. A passage is formed in a passage that communicates with the intake passage on the secondary side extending immediately before the intake valve, and cooling water is provided on the sides of the intake passage on the primary side and the distribution passage in the adapter to heat both passages. 1. An air intake system for an internal combustion engine, comprising a jacket and configured so that only the primary fuel system is heated by engine cooling water flowing through the cooling water jacket.