JPS6118655B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an internal combustion engine having a carburetor for each cylinder, in particular a carburetor for each cylinder, and in addition to a main intake passage leading to each cylinder, a sub intake passage is provided for each cylinder. It relates to an internal combustion engine configured to open toward a cylinder.

In an internal combustion engine, it is effective as an exhaust gas purifying means for the engine to provide a sub-throttle valve in the intake passage that closes during low loads, including idling, and to open the sub-intake passage that bypasses the sub-throttle valve toward the cylinders. That is, the inlet of the auxiliary intake passage opens into the main intake passage on the upstream side of the auxiliary throttle valve, and the outlet faces the cylinder, for example, in the vicinity upstream of the intake valve or opens into the cylinder through a suitable valve. Adopted. When this type of intake system is applied to a multi-cylinder internal combustion engine having a carburetor for each cylinder, providing a sub-throttle valve and a sub-intake passage for each cylinder complicates the structure. Furthermore, in such conventional intake systems, each carburetor was provided with a starting fuel supply device and a slow-only fuel supply device such as an idle port and a pilot valve, so as the number of cylinders increased, the structure became more complicated. The system became complicated, and there were maintenance problems such as the need to adjust the idle for each cylinder.

The present invention aims to solve such conventional problems, and is an intake system for a multi-cylinder internal combustion engine with an auxiliary intake passage, which has a carburetor for each cylinder. It is an object of the present invention to provide a device that can control the supply of air-fuel mixture during operation. Therefore, the intake system of the present invention is particularly suitable for use in multi-cylinder internal combustion engines of the type that have a carburetor for each cylinder, such as sports-type automobiles.

The intake device according to the present invention is provided with a sub-throttle valve that opens later than the throttle valve of the carburetor of one cylinder, and the opening/closing operation of the sub-throttle valve is controlled by the throttle valve of the carburetor of the other cylinder. A branched auxiliary intake passage having an inlet opening into the intake passage is provided between the throttle valve of the carburetor of the one cylinder and the auxiliary throttle valve in response to opening/closing operations, and the auxiliary intake passage is directed toward each cylinder. It is characterized by being designed to open. In particular, the sub-intake passage,
In the one cylinder, the carburetor of the cylinder is opened downstream of the sub-throttle valve, and in the other cylinder, the carburetor of that cylinder is opened downstream of the throttle valve, into the intake passage of each cylinder.

In this case, an idle port that opens between the throttle valve and the sub-throttle valve is provided only in the carburetor of the one cylinder, and the idling air-fuel mixture is supplied to each cylinder through the branched sub-intake passage; It is preferable to simplify the structure and balance each cylinder. In addition, the idling port is provided only in the carburetor of one cylinder, and an air amount correction passage that bypasses the throttle valve of the carburetor and opens on both sides of the throttle valve and is open on both sides thereof is provided, and the amount of idling air for each cylinder is provided. It is preferable to correct this so that smooth idling operation can be ensured under any conditions.

Furthermore, the structure can be simplified by providing a starting fuel supply device such as a choke valve only in the carburetor of the one cylinder and supplying starting fuel to each cylinder through the auxiliary intake passage. In this case, the throttle valve is forcibly opened before the sub-throttle valve and the throttle valves of other cylinders begin to open.

Further, the flow rate adjustable air amount has an inlet between the bench lily of the carburetor of the one cylinder and the throttle valve, and has an outlet on the downstream side of the sub-throttle valve, bypassing the throttle valve and the sub-throttle valve. Preferably, an adjustment passage is provided to compensate for a lack of air in the one cylinder caused by negative pressure suction in the other cylinders during idling and low load operation.

Furthermore, a transient fuel supply port is provided near the carburetor throttle valve of the other cylinder so that fuel can be supplied at the same time as air starts flowing through the throttle valve, thereby reducing the time delay in fuel supply from the main system. It is preferable to complement and improve the fuel supply connection during acceleration.

Embodiments of an intake system for an internal combustion engine according to the present invention will be described below with reference to the drawings.

1 to 5 show preferred embodiments of the intake device of the present invention.

In FIG. 1, an independent carburetor 1 is provided for each cylinder 14 of a multi-cylinder (four-cylinder) internal combustion engine 12.
6 are connected, and each intake passage 18 communicates with an intake valve 20 of each cylinder.

As shown in FIG. 2, each cylinder 14 is connected to a cylinder 22.
A combustion chamber 28 is defined between the upper surface of the piston and a cylinder head 26. In addition to the intake valve 20, an exhaust valve 30 and a spark plug 32 are provided in the combustion chamber.
Cams 34 and 36 for controlling the opening and closing of the intake valve 20 and the exhaust valve 30 are arranged in the upper portion of the cylinder head. In the four-cylinder internal combustion engine shown in FIG. 1, the engine operating strokes of each cylinder are shifted in phase at equal intervals (every 90 degrees of the crankshaft).

Further, an outlet (jet port) 38 of the auxiliary intake passage is formed near the upstream of the intake valve 20 of each cylinder 14, and an air flow (air mixture flow) having high speed and large kinetic energy flows from the outlet during the intake stroke of each cylinder. The combustion chamber 2
By injecting the gas into the combustion chamber 8 and stirring the gas in the combustion chamber, the combustion speed is increased particularly during low load operation, thereby improving combustion and purifying the exhaust gas.

According to the intake system of the present invention, one of the plurality of cylinders (four cylinders) (the second cylinder from the right in FIG. Two throttle valves, namely a throttle valve 40 and a sub-throttle valve 42 disposed downstream thereof, are provided, and an inlet opening 46 of a sub-intake passage 44 is formed between the throttle valves and the sub-throttle valve. . On the other hand, in other cylinders, as shown in FIG.
Only one throttle valve 48 is provided therein, and an inlet opening of the sub-intake passage 44 is not formed.

As shown in FIGS. 1 to 3, the auxiliary intake passage 44, which has an inlet opening 46 in the intake passage of one cylinder, branches into four parts in the middle and connects to each intake passage near the upstream of the intake valve of each cylinder. It has an outlet 38 that opens.

When opening the throttle valve 40 of the carburetor of one cylinder, the sub-throttle valve 4 provided downstream
2 is configured to open later than the throttle valve 40. In addition, the throttle valve 48 of the carburetor of the other cylinders
The throttle valves 48 (three throttle valves 48 in the embodiment shown in FIG. 1) are configured to operate in conjunction with the opening and closing of the sub-throttle valve 42 and to move in unison. Therefore, if the sub throttle valve 42 is in the fully closed position, all the throttle valves 48 of the carburetors of the other cylinders are also in the fully closed position. Further, the carburetor of the one cylinder is provided with a choke valve 52 as a starting fuel supply device upstream of the bench lily 50. The carburetors of the other cylinders are not particularly provided with a starting fuel supply device such as a choke valve.
The throttle valve 52 is configured to be forcibly opened before the sub-throttle valve 42 and the throttle valve 48 of the carburetor of the other cylinder begin to open.

Examples of the opening/closing mechanism of these throttle valves 40, 42, 48 and the choke valve 52 are shown in FIG.
This is as shown in FIGS. 4 and 5. In this embodiment, the driver's control operation is performed by pulling the first lever 60 in the direction of arrow A via a control cable or the like. When this one lever 60 is not pulled, the throttle valves 40, 42, 48 and the choke valve 52 are all closed.

The first lever 60 has a shape as shown in FIG. 5, and when pulled in the direction of arrow A through the hole 60A at the beginning of the opening/closing operation, it rotates clockwise in FIG. 5 about the upper hole 60B. do. The portion of the hole 60B can be rotated by a fulcrum pin 64 of a parallelogram-shaped link 62A, 62B, 62C that connects the auxiliary throttle valve 42 and the throttle valve 48 of the carburetor of another cylinder for synchronous rotation. is supported by. Further, a long hole 60C is formed in the first lever 60, and a second lever 66, which is attached to the shaft of the throttle valve 40 of the carburetor of the one cylinder and rotates together, is planted in the long hole. A pin 68 is slidably fitted.

Therefore, in the initial stage of the valve opening operation, the second lever 66 is rotated by clockwise rotation of the first lever 60.
rotates counterclockwise to slightly open the throttle valve 40 of the one cylinder. At this initial stage, the link mechanisms 62A, 62 are arranged in a parallelogram.
Since B and 62C do not rotate at all, the sub throttle valve 42
The throttle valves 48 of the carburetors of the other cylinders are still closed. However, since the operating lever 72 of the throttle valve 52 is connected to the second lever 66 via the rod 70, in the initial stage when the second lever rotates to a predetermined position and slightly opens the throttle valve 40, The valve will be opened. That is, during low load operation when the sub throttle valve 42 and the throttle valves 48 of other cylinders are still closed, the throttle valve 52 is already in the open state.

The first lever 60 is further rotated to open the throttle valve 4.
When 0 reaches a certain opening position, the pin 68 of the second lever engaged with the elongated hole 60C of the first lever is latched onto one end of the elongated hole. Therefore, when the first lever 60 is further pulled, the second lever 66 is rotated counterclockwise to further open the throttle valve 40, and at the same time, the link mechanisms 62A, 62B, and 63C are rotated counterclockwise in FIG. (or to the left). When the link mechanism rotates, the sub-throttle valves 42 and the throttle valves 48 of the other cylinders (the remaining three cylinders), which are connected to each other, all begin to open at the same time.

By the mechanism described above with reference to FIGS. 1, 4, and 5, the throttle valve 4 of the one cylinder is
The sub-throttle valve 42 provided on the downstream side of the throttle valve 4
The throttle valves 48 of other cylinders (in the illustrated embodiment, the throttle valves of the remaining three cylinders) open and close at the same time as the sub-throttle valve 42. Further, when a throttle valve 52 is provided in the one cylinder as a starting fuel supply device, the throttle valve is forcibly opened before the sub throttle valve 42 and the throttle valves of the other cylinders begin to open.

Next, with reference to FIGS. 2 and 3, a fuel supply system for the intake system of the present invention will be described.

A bench lily 50 is provided upstream of the throttle valve 40 or 48 of each cylinder, and a main system fuel supply port 80 opens in the vent lily. Therefore, during output operation (normal operation),
Similar to conventional intake systems, fuel is measured and the mixture is prepared for each cylinder.

However, starting, idling, and low load fueling is primarily controlled by only the one cylinder carburetor.

First, the chiyoke valve 5 as a starting fuel supply device
2 is provided only in the one cylinder, and the rich mixture prepared by closing the choke valve is not only supplied to the one cylinder, but also supplied to the branched sub-intake passage 44. It is also supplied to other cylinders through the Therefore, by providing only one check valve, it is possible to uniformly supply the rich air-fuel mixture required at startup to each cylinder.

Next, the idle port 82 is provided only in the carburetor of the one cylinder, and the throttle valve 40 and the sub-throttle valve 4
There is an opening between the two. Therefore, during idling, fuel flows from the one cylinder to the sub-intake passage 44.
is supplied to each cylinder through the Further, part of the air required for idling is secured by leakage from the throttle valves 48 of other cylinders in the closed position, and the rest is secured by the opening of the throttle valve 40. However, when the throttle valve 48 of each cylinder is closed, the amount of air leakage tends to decrease due to garbon deposition due to blowback from the combustion chamber. An air amount correction passage 84 is provided for correcting such a reduction in air leakage amount when it occurs. The air amount correction passage is formed as a passage that bypasses the throttle valve 40 and opens on both sides of the throttle valve 40, and is provided with a screw 84A for adjusting the flow rate in the middle thereof. Since the air replenished through the air amount correction passage is supplied to each cylinder through the auxiliary intake passage 44, a uniform mixture of desired concentration can be supplied to each cylinder, and smooth idling can be ensured. .

Further, a low-load fuel supply port 86 (low-speed port) is formed near the throttle valve 40 of the carburetor of the one cylinder, and the fuel supplied from the port passes through the sub-intake passage 44 to the other cylinders. is also supplied and used for low load operation of each cylinder.

In this case, the carburetor of the one cylinder has an inlet between the throttle valve 40 and the bench lily 50, bypasses the throttle valve and the sub-throttle valve 42, and has an outlet downstream of the sub-throttle valve. It is preferable to form the air amount adjustment passage 88 having the following. A screw 88A for adjusting the flow rate is also provided in this passage.
The purpose of forming this air amount adjustment passage 88 is to control the amount of air that leaks from the auxiliary throttle valve 42 of the intake passage of one cylinder and is taken into the cylinder during low load, and to control the amount of air that leaks from the sub-throttle valve 42 of the intake passage of one cylinder and adjusts the amount of air that is This is to balance the amount of air that leaks from the cylinder and is sucked into the cylinder.

As explained above, in the intake system of the present invention, fuel supply during starting, idling, and low load operation is controlled only by the one cylinder, and the branched auxiliary intake passage has an inlet only in that cylinder. The air is supplied to each cylinder from each outlet opened near the upstream side of the intake valve of each cylinder through the air. Note that in a range where the opening degree of the throttle valve 40 is above a predetermined value, such as in normal operation or output operation, the fuel supply to each cylinder is controlled by the main system fuel passage for each carburetor.

Therefore, in the case of a cylinder other than the one cylinder, that is, in a carburetor of another cylinder, a transient fuel supply port 90 is formed near the throttle valve 48. This port is provided to compensate for the delay in fuel injection from the main system port 80 when the throttle valve 48 is opened, and to smooth the transition from low-speed operation to high-speed operation. In other words, during the transition period when there is a delay in fuel injection from the main system port, fuel is immediately supplied in response to the opening of the throttle valve 48 to maintain a good connection as the opening increases. .

Since the intake system for an internal combustion engine according to the present invention has the configuration and operation described above, it can achieve the following effects.

In a multi-cylinder internal combustion engine having a carburetor for each cylinder, only one carburetor is provided with a fuel supply device for starting and low load operation such as a choke valve, an idle port, and a low load port. Since the fuel prepared in this way is supplied to each cylinder through the branched auxiliary intake passage, the structure of the internal combustion engine can be extremely simplified. At the same time, it is possible to make the fuel supply uniform at low loads, which conventionally tends to vary from cylinder to cylinder, and to provide a multi-cylinder engine that is extremely easy to adjust and maintain. . Since a multi-cylinder internal combustion engine in which a carburetor is provided for each cylinder is suitable for sports-type automobiles, the intake system of the present invention is particularly suitable for use in sports-type automobiles (including motorcycles). ing.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a four-cylinder internal combustion engine in which the intake system of the present invention is adopted, FIG. 2 is a sectional view taken along the line - in FIG. 1, and FIG. A sectional view taken along the line in the figure, FIG. 4 is a partially sectional side view taken along the line in FIG.
FIG. 5 is an exploded perspective view showing the main parts of a link mechanism for opening and closing the throttle valve and the choke valve of the intake system shown in FIG. 1. The same reference numbers in each figure indicate the same parts, 12... internal combustion engine, 14... cylinder, 16...
...carburizer, 18...intake passage, 20...intake valve,
28... Combustion chamber, 38... Outlet of sub-intake passage, 4
0... Throttle valve, 42... Sub-throttle valve, 44... Sub-intake passage, 46... Entrance of the sub-intake passage, 48... Throttle valve of the carburetor of another cylinder, 50... Bench lily,
52...Chiyoke valve, 80...Main system fuel supply port, 82...Idle port, 84...Air amount correction passage, 86...Low speed port, 88...Air amount adjustment passage, 90...Transient fuel supply port are shown respectively.

Claims (1)

[Scope of Claims] In an intake system for an internal combustion engine having a carburetor for each cylinder, a sub-throttle valve that opens later than the throttle valve is provided downstream of the throttle valve of the carburetor of one cylinder, and the sub-throttle valve opens later than the throttle valve. A branched auxiliary intake having an inlet opening into the intake passage between the throttle valve of the carburetor of the one cylinder and the auxiliary throttle valve, the opening and closing operation of which corresponds to the opening and closing operation of the throttle valve of the carburetor of the other cylinder. A passage is provided, and this auxiliary intake passage is connected to the intake passage of each cylinder in the one cylinder downstream of the auxiliary throttle valve, and in the other cylinder to the carburetor of that cylinder downstream of the throttle valve. An intake device for an internal combustion engine, characterized in that it is opened. 2. The intake system for an internal combustion engine according to item 1, wherein an idle port that opens between a throttle valve and the sub-throttle valve is provided only in the carburetor of the one cylinder. 3. The intake system for an internal combustion engine according to item 2, characterized in that the carburetor of the one cylinder is provided with an air amount correction passage that bypasses the main throttle valve and opens on both sides of the main throttle valve. 4. The intake system for an internal combustion engine according to any one of items 1 to 3 above, characterized in that a chioke valve is provided as a starting fuel supply device only in the carburetor of the one cylinder. 5. In the above item 4, a chiyok valve is used as the starting fuel supply device, and a mechanism is provided to forcibly open the chiyok valve before the sub throttle valve and the throttle valve of the carburetor of the other cylinder start to open. An intake system for an internal combustion engine characterized by: 6. In any one of the above items 1 to 5, an inlet is provided between the vent lily of the carburetor of the one cylinder and the throttle valve, and the throttle valve and the sub-throttle valve are bypassed to bypass the sub-throttle valve. An intake device for an internal combustion engine, characterized in that an air amount adjustment passage having an outlet on the downstream side of a valve is provided. 7. In any of the above items 1 to 6, a transient fuel supply port is provided that opens near the throttle valve of the carburetor of the other cylinder, and fuel is supplied at the same time as air inflow starts through the throttle valve. An intake system for an internal combustion engine, characterized in that it can compensate for a delay in fuel injection in a main system.