JPS638814Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement in an intake system for a multi-cylinder internal combustion engine, particularly one that employs an intake air supply system called inertial supercharging.

Generally, in multi-cylinder internal combustion engines for automobiles,
In order to increase the intake air filling efficiency, the length of the intake air flow path (in this case, the confluence point where each branch of the intake manifold gathers) is made variable, and the length of the intake air flow path is varied depending on the period of intake pressure vibration and the engine speed. An intake system is used that achieves good inertial intake action by matching the changing intake valve opening/closing cycle over as wide an operating range as possible of the engine.

BACKGROUND ART Conventionally, there is an air intake device of this type as shown in FIG. 1 (Japanese Patent Application Laid-open No. 115818/1983).

This is the intake manifold 1 of a 6-cylinder engine.
is composed of branch portions 2 connected to each cylinder #1 to #6 of the engine, and a downstream gathering chamber 3 where these branch portions 2 are assembled, and the downstream gathering chamber 3 has a central A switching valve 4 is interposed at the position.

In other words, the switching valve 4 controls the downstream gathering chamber 3.
However, each of the cylinders #1 to #6 mentioned above is made to explode at equal intervals (when the ignition order is #1 → #4 → #2 → #6 → #3 → #5, etc.), and A space 3A communicating with the first cylinder group A consisting of cylinders, and #4 to
Space 3 communicating with second cylinder group B consisting of #6 cylinders
It is defined by B.

A passage 5 whose downstream end is open-connected to the space 3A side of the downstream gathering room 3 and a passage 6 whose downstream end is open-connected to the space 3B side are arranged in parallel. The upstream end is opened and connected to the upstream gathering chamber 7. An intake air introduction pipe 8 is connected to the upstream gathering chamber 7, and this intake air introduction pipe 8 may be directly released to the atmosphere or may be connected to an air cleaner or the like.

In this configuration, furthermore, when the engine speed is below a predetermined value, the above-mentioned switching valve 4 is closed to cut off the space 3A and the space 3B, and when the engine speed exceeds a predetermined value, the switching valve 4 is opened to communicate the space 3A and the space 3B. Configure it to do so.

With this configuration, in a low engine speed range when the switching valve 4 is closed, the intake passage communicating with the first cylinder group A and the intake passage communicating with the second cylinder group B merge in the upstream gathering chamber 7.

The upstream collecting chamber 7 communicates with all the cylinders #1 to #6 and continuously receives the suction negative pressure from each cylinder to maintain a substantially constant negative pressure. On the other hand, since the intake valve opening timings of the cylinders in the first and second cylinder groups A and B do not substantially overlap with each other, the spaces 3A and 3B defined by the switching valves 4 in the downstream collective chamber 3 is affected only by the intake pressure from one cylinder having an intake stroke in each corresponding cylinder group.

Therefore, the pressure waves of intake pressure vibration generated from the cylinders in the intake stroke in the first cylinder group A and the second cylinder group B are transmitted from the combustion chambers of the cylinders via the corresponding manifold branches 2 and spaces 3A or 3B. Since the intake pressure oscillation propagates back and forth through the flow path leading to the upstream gathering chamber 7, the period (natural frequency) of the intake pressure vibration is determined by the upstream gathering chamber 7, that is, the position of the confluence of the intake passages.

Therefore, by setting the period of intake pressure vibration determined by the mounting position of the upstream gathering chamber 7 in accordance with the opening/closing cycle of the intake valve in the low speed range of the engine, intake inertia supercharging in the low speed range can be achieved. You can do good deeds.

On the other hand, in the engine high speed range where the switching valve 4 is opened, the space 3A and the space 3B in the downstream gathering chamber 3
Since these are in communication with each other, the entire space within the collective chamber 3 continuously receives the negative pressure of all cylinders #1 to #6 and is maintained at a substantially constant negative pressure.

Therefore, the downstream gathering chamber 3 has the same pressure buffering function as the upstream gathering chamber 7 in the engine low speed region, and this time, the pressure wave of intake pressure vibration is transmitted downstream from the combustion chamber of the cylinder in the intake stroke. It propagates back and forth through the flow path leading to the collection chamber 3.

In this case, the pressure wave propagation path is shortened compared to the case in the low engine speed range, so the cycle of intake pressure oscillation increases, and it matches well with the intake valve opening/closing cycle in the high engine speed range, even in the high speed range. This results in good intake inertia supercharging.

As a result, the filling efficiency η _v of the intake air with respect to the engine speed N is determined by the period of the intake pressure vibration and the intake valve 4, respectively, in the engine low speed range where the switching valve 4 is closed and in the engine high speed range where the switching valve 4 is opened, as shown in FIG. The opening/closing period has two maximum points C and D that are matched to achieve the best inertial supercharging, and this allows good intake air filling efficiency to be obtained over a wide speed range of the engine. be.

Further, based on the same technical concept, as shown in FIG. 3, a partition wall partitions a passage 5 connected to a space 3A communicating with the first cylinder group A and a passage 6 connected to a space 3B communicating with the second cylinder group B. It has also been proposed that 9 is constructed of a movable partition whose terminal end 9A, that is, the confluence of the intake passages, can be gradually moved downstream as the engine speed increases. In the figure, 10 is an engine rotational speed detection device, and 11 is a motor that controls the movement of the movable bulkhead 9 based on a detection signal from the detection device 10.

According to this, the vibration period of the intake pressure vibration and the intake valve opening/closing period can be optimally matched over the entire speed range of the engine, and an optimal inertial supercharging effect can always be obtained.

However, in such conventional intake devices, the confluence point of the intake passages is made variable by the switching valve 4 provided in the downstream gathering chamber 3 of the intake manifold 1 as shown in FIG. The flow path length can be switched in two stages by opening and closing at most one switching valve 4, and therefore the period of intake pressure vibration and the period of opening and closing of the intake valve can be optimized over the entire speed range of the engine. However, there was a problem in that it was impossible to achieve matching, and the full effect of inertial supercharging could not be obtained.

In addition, as shown in Fig. 3, where the confluence point is continuously changed by the movable bulkhead 9, optimal control as described above is theoretically possible;
It is almost impossible to create a practical mechanism for controlling the excess intake passage partition wall in response to constantly changing operating conditions using the method described above.

This idea was devised by focusing on these conventional problems, and the intake passage connected to each cylinder is designed to have at least two inertia filters that converge independently so that explosions occur at equal intervals. A supply duct is provided, and branch pipes that are located downstream of the confluence of these two ducts and communicate the two ducts with each other are spaced apart at predetermined intervals in the length direction of the duct, and A plurality of branch pipes are provided so that the length of the other branch pipe is extended until the middle part of the branch pipe located most downstream approaches the middle part of the branch pipe, and the branch pipe is placed in the middle part of these branch pipes. By providing open/close valves that communicate and shut off depending on the engine operating condition, the confluence point of the intake passage can be varied in multiple stages depending on the engine operating condition, completely eliminating inertia over the entire engine speed range. It is an object of the present invention to provide an intake device that is effective in terms of cost, space, and reliability by making it possible to centrally control the plurality of on-off valves while providing a feeding function.

Hereinafter, embodiments of this invention will be described based on the drawings.

As shown in FIG. 4, the downstream collecting chamber 3 of the intake manifold 1 of a six-cylinder engine is a left collecting chamber 3A communicating with the first cylinder group A and a right collecting chamber 3B communicating with the second cylinder group B. The inertia supercharging ducts 5,
6 are led out in parallel, and both these ducts 5 and 6 are joined at their upstream ends to form an upstream gathering chamber 7.
form.

A plurality of branch pipes 12 to 14 (three in the figure) are provided downstream of the confluence of the inertial supercharging ducts 5 and 6 to communicate the two ducts 5 and 6 with each other.

The branch pipes 12 to 14 have their respective branch points 12
a to 14a are spaced apart from each other at predetermined intervals in the duct length direction, while the intermediate portion 14b of the branch pipe 14 located most downstream is located at the intermediate portion 12 of the other branch pipes 12 and 13.
b, 13b approach the other branch pipes 12, 1.
It is arranged so as to extend the length of 3.

Further, each of the branch pipes 12 to 14 is set to have a predetermined pipe diameter so as to be thinner than the inertial supercharging ducts 5 and 6.

Further, the intermediate portions 12b to 12b of each of the branch pipes 12 to 14 are
14b, on-off valves 15A to 15 that connect and shut off the branch pipes 12A to 12C depending on the operating state of the engine.
C is interposed respectively.

The on-off valves 15A to 15C respond to a detection signal from a sensor that detects the engine speed, and as the engine speed increases, the on-off valve 15 is positioned on the upstream side.
It is configured to sequentially open the on-off valve 15C located downstream from A.

The rest of the structure is the same as in FIG. 1, so the same members as in FIG. 1 are given the same reference numerals and detailed explanations will be omitted.

Because of this configuration, in this embodiment, the confluence points of the intake passages that determine the period of intake pressure vibration can be varied at four locations by opening and closing the on-off valves 15A to 15C described above.

In other words, the upstream gathering chamber 7 when all on-off valves 15A to 15C are closed, the branch pipe 12 when on-off valve 15A is opened and on-off valves 15B and 15C are closed, and the on-off valve 15B is opened. Open/close valve 1
5C is closed (at this time, the on-off valve 15A may be either one), and when the on-off valve 15C is opened (at this time, the on-off valves 15A and 15B are
are the four locations of the branch pipe 14 (whichever is acceptable).

And the on-off valves 15A to 15C as described above.
By controlling the opening and closing of the flow path, the effective merging point is switched and moved downstream (in other words, in the direction of shortening the flow path length) as the engine speed increases.

Therefore, if the mounting positions of the above-mentioned merging points (including the volume determined by the pipe diameter) are set sequentially in accordance with the intake valve opening/closing cycle that changes depending on the engine speed, the engine will be as shown in Fig. 5. A good inertial supercharging effect can be obtained over the entire speed range, and since the intake air filling efficiency can be improved accordingly, the engine performance, especially the output performance, can be greatly improved.

In other words, in the conventional example, as shown in Fig. 2, there were two maximum points C and D where the cycle of intake pressure vibration and the intake valve opening/closing cycle were matched to achieve the best inertial supercharging. In this example, the fifth
As shown in the figure, the intake air filling efficiency characteristic has four maximum points C, D, E, and F within the practical rotational speed range, which is the same as in the conventional example.

In addition, in this embodiment, the lengths of the plurality of branch pipes 12 and 13 are extended so that the intermediate portions 12b to 12c, in which the on-off valves 15A to 15C are interposed, are arranged close to one location. Therefore, the above on-off valve 15A
-15C can be centrally controlled with a single actuator, which has the advantage of realizing an effective intake device in terms of cost, space, and reliability.

That is, the intermediate portions 12b to 12 of the branch pipes 12 to 14
If the on-off valves 15A to 15C are not close to each other, the device may be unnecessarily complicated by installing an actuator for each of the on-off valves 15A to 15C located at a distance, or by remotely operating a plurality of on-off valves 15A to 15C with one actuator. This avoids the possibility of

As explained above, according to this invention, the branch pipes that interconnect at least two inertial supercharging ducts are separated from each other in the length direction of the ducts, and the branch pipes are located at the most downstream position. A plurality of branch pipes are provided so that the length of the other branch pipes is extended until the middle part of the branch pipe is close to the middle part of the branch pipe, and the branch pipe is connected to the middle part of these branch pipes in accordance with the operating state of the engine. Since we have provided on-off valves that open and shut off communication depending on the engine speed, the confluence point of the intake passage can be varied in multiple stages depending on the engine operating condition, ensuring full inertial supercharging over the entire engine speed range. At the same time, it is possible to centrally control the plurality of on-off valves, thereby providing an effective intake device in terms of cost, space, and reliability.

[Brief explanation of drawings]

1 and 3 are schematic configuration diagrams of different conventional examples, and FIG. 2 is an explanatory diagram showing the intake air filling efficiency characteristics of FIG. 1. FIG. 4 is a schematic configuration diagram of an embodiment of this invention, and FIG. 5 is an explanatory diagram showing its intake air filling efficiency characteristics. 1... Intake manifold, 3A, 3B... Collection chamber, 5, 6... Inertia supercharging duct, 7... Upstream collection chamber, 12-14... Branch pipe, 12a-14a...
... Branching point, 12b-14b ... Middle part, 15A-
15C...Opening/closing valve.

Claims (1)

[Scope of utility model registration request] At least two inertial supercharging ducts are provided that are assembled independently so that the intake passages connected to each cylinder are evenly spaced. Branch pipes that communicate with each other are spaced apart at predetermined intervals in the length direction of the duct, while the middle parts of other branch pipes are close to the middle part of the branch pipe located most downstream. A plurality of branch pipes are provided so as to extend the length of the other branch pipes, and an on-off valve is provided in the middle of each of these branch pipes to communicate or shut off the branch pipes depending on the operating state of the engine. Intake system for multi-cylinder internal combustion engine.