JP2771176B2 - Engine intake system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake device for an engine in which intake efficiency is improved by a resonance effect.

[Conventional technology]

2. Description of the Related Art Conventionally, various intake devices for an engine in which charging efficiency is increased by a dynamic effect of intake air have been known. For example, in the device disclosed in Japanese Patent Publication No. 60-14169, in a multi-cylinder engine, the intake system is divided into two groups in which cylinders in which the order of intake is not continuous are the same.
Each of the two groups of intake systems is provided with a large-volume collecting portion to which the upstream end of an independent intake passage (intake manifold branch) for each cylinder is connected, and a resonance passage extending upstream from the collecting portion. Along with the above-mentioned gathering part,
A switching device is provided to enable the communication between the intake systems of the respective groups to be interrupted, and the upstream ends of the respective resonance passages are connected to the upstream collecting chamber. When the switching device is in a state in which the respective groups are shut off from each other, the upstream collecting chamber is obtained such that a supercharging action is obtained in a low-speed region of the engine by the intake pressure wave reflected by the upstream collecting chamber. In addition to setting the natural frequency of the intake system between each intake port and each intake port, when the switching device is in a state of communicating with each intake passage, inertia due to the independent intake passage in a relatively high speed range The length of the independent intake passage is set so that a supercharging effect (a supercharging effect due to the pressure wave reflected at the upstream end of the independent intake passage acting at the end of intake for each cylinder) is obtained. .

[Problems to be solved by the invention]

When the supercharging action in the high-speed range is obtained by the inertia effect of the independent intake passage of the cylinder as in the above-described intake device, it is necessary to have the inertia effect in the practical rotation speed range even in the high-speed range. The independent intake passage needs to be formed to a certain length so that the inertial tuning rotational speed of the independent intake passage is lower than the maximum allowable rotational speed of the engine. However, since the independent intake passage is provided for each cylinder, it is difficult to make the intake system compact if each independent intake passage is formed long.

When the intake system is divided into two groups as described above, in addition to the inertial effect of the independent intake passage, a resonance system including a passage portion communicating with the collection portion of the independent intake passage and the upstream side thereof and the like is included. Although the resonance effect due to the resonance of the pressure wave can be expected, if the inertial tuning rotational speed of the independent intake passage is set to be lower than the maximum allowable rotational speed of the engine as described above, the natural vibration of the independent intake passage Since the resonance frequency is governed by the number and the resonance natural frequency of the resonance system cannot be sufficiently increased, it is difficult to have a resonance effect in a high speed range. And
In a gasoline engine having a higher allowable maximum rotational speed than a diesel engine, it is often set to be lower than the inertial synchronous rotational speed. Further, when a resonance effect is to be provided in a high-speed range, an imbalance is easily generated in a resonance supercharging operation for each cylinder due to a difference in length from an intake port of each cylinder to an upstream communication portion, and intake air distribution is performed. Problems remained in terms of gender.

In view of the above circumstances, the present invention can increase the engine output by the resonance effect in the high-speed range of a gasoline engine while shortening the length of each independent intake passage for each cylinder to make the intake system compact, and The present invention provides an intake device for an engine, which can also improve the distribution of the engine.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a gasoline engine provided with intake air amount detection means upstream of an intake passage, wherein a plurality of cylinders in which the order of intake of the engine is not the same in the intake group are set to the same group. Divided into groups, the independent intake passages for each cylinder are grouped for each group, and the independent intake passages are set such that the inertia-tuned rotation speed by this passage is higher than the maximum allowable rotation speed of the engine, and In the middle of each collecting passage in which the independent intake passages are gathered for each group, a communication passage connecting the respective collecting passages is connected, and the independent intake passage and the collecting passage of each said group and a passage portion communicating with each collecting passage. In addition to forming a resonance system with the communication passage, an on-off valve is provided in the communication passage, and the on-off valve is opened in a high-speed region of the engine and closed in a low-speed region. .

[Action]

According to the above configuration, in the gasoline engine, the inertia tuning speed by the independent intake passage for each cylinder is set to be higher than the maximum permissible engine speed, thereby substantially relying on the inertial effect by the independent intake passage. Instead, a supercharging effect in a high-speed range can be obtained by the resonance effect of the resonance system including the collective passage and the communication passage. With the above setting, the length of the independent intake passage is sufficiently reduced, and the natural frequency of the resonance system can be set high without being influenced by the natural frequency of the independent intake passage.
By connecting the communication passage in the middle of each collecting passage, a resonance supercharging effect is effectively exerted on each cylinder. Further, by changing the inherent sliding number of the resonance system in accordance with the opening and closing of the on-off valve, the resonance supercharging action can be effectively obtained in each of the low speed region and the high speed region.

〔Example〕

FIG. 1 shows an embodiment of the apparatus of the present invention. The engine shown in this figure is a V-type six-cylinder engine, and one of the banks 1 has three first, second, and third engines. Cylinder 3a, 3
b and 3c are provided, and the other bank 2 is provided with three cylinders 3d, 3e and 3f of fourth, fifth and sixth cylinders. Each cylinder 3a above
3f are respectively provided with intake ports 4a to 4f and an exhaust port (not shown), and these ports are respectively opened and closed at predetermined timing by intake valves and exhaust valves (not shown). Intake order (ignition order) of each of the cylinders 3a to 3f
Is the first cylinder 3a → the fourth cylinder 3d → the second cylinder 3b → the fifth cylinder 3e
→ The third cylinder 3c → the sixth cylinder 3f.

The intake system of this engine is divided into two groups in which cylinders in which the intake order is not continuous are the same group, that is, according to the intake order, each cylinder 3a of one bank 1
3c do not have a continuous intake order, and the cylinders 3d to 3f of the other bank 2 do not have a continuous intake order. Therefore, the intake system has one bank 1 side group (first group) and the other two side. Group (second group). Each of the independent intake passages 5a to 5c connected to each of the intake ports 4a to 4c of the first group and each of the independent intake passages 5d to 5d to each of the intake ports 4d to 4f of the second group.
5f, for each group, the upstream end side is the collecting passage 6,
Collected by being connected to 7.

The length of each of the independent intake passages 5d to 5f is sufficiently shortened so that the inertia-tuned rotational speed of each of the independent intake passages 5d to 5f is equal to the maximum allowable rotational speed of the engine (permissible in terms of engine reliability and the like). Is set to be higher than the maximum rotation speed.

Each of the collective passages 6, 7 is arranged in the cylinder row direction, and one end of each of the collective passages 8, 9 is connected to passages 8, 9 extending upstream, and the upstream ends of the passages 8, 9 communicate with each other. It is connected to a common intake passage 10. In the common intake passage 10,
From the upstream side, air cleaner 11 and air flow meter 1
2 and a throttle valve 13 are provided.

In addition, a relatively short communication passage 14 that connects the two collection passages 6 and 7 to each other is formed in the middle of the collection passages 6 and 7 at substantially the center of a range that reacts with the cylinder arrangement portion. This communication passage
The on-off valve 14 is provided with an on-off valve 15 which is closed in a low-speed range of the engine and opened in a high-speed range by operating means (not shown).

Thus, the downstream side of the air flow meter 12 (intake air amount detecting means), the independent intake passages 5a to 5f of the respective groups, the passages 6,7, and the passage portions 8,9 which are connected to the respective passages 6,7, and the passages 8,9. The passage 14 forms a resonance system, and the number of inherent sliding of the resonance system changes according to the opening and closing of the on-off valve 15. The engine is a gasoline engine, as is clear from the fact that the air flow meter 12 is provided in the intake passage. Generally, the gasoline engine has a higher allowable maximum rotational speed than the diesel engine.
Nmax is high.

According to the intake device of this embodiment, the on-off valve
In a state where 15 is closed, the upstream end side communication points of the passage portions 8 and 9 connected to the respective collecting passages 6 and 7 serve as resonance pressure reversing portions,
A portion extending from the independent intake passages 3a to 3c of the first group to the collective passage 6 and the passage portion 8, and an independent intake passage 3d of the second group
3f to the collecting passage 7 and the passage 9 constitute a resonance path for each group.
15 is open, the independent intake passages 5a to
A portion extending from 5c, 5d to 5f to the communication path 14 forms a resonance path.

As described above, the resonance system is configured by dividing the intake system into two groups in which cylinders in which the order of intake is not continuous are the same group, so that pressure waves generated by the operation of each cylinder propagate in each group. Then, pressure vibration is generated in a portion constituting the resonance system, and when the resonance natural frequency matches the number of inhalations for each group, the pressure vibration is intensified by resonance. The supercharging effect by the resonance effect is obtained in the rotation speed range near the resonance tuning rotation speed in such a state, and the engine output is increased.

In a state where the opening / closing valve 15 is opened and the collecting passages 6 and 7 of each group are communicated with each other by the relatively short communication passage 14, the natural frequency of the resonance system is increased, and the resonance effect is obtained in a high speed region. Be demonstrated.

In this case, the inertia-tuned rotational speeds of the individual intake passages 5a to 5f for each cylinder are set to be higher than the maximum allowable rotational speed of the engine, and the supercharging action in the high-speed range within the practical rotational speed range is independent. Instead of relying on the inertial effect of the intake passages 5a to 5f, the resonance effect is obtained, so that the length of each independent intake passage 5a to 5f can be made sufficiently short to make the intake system compact. it can. That is, assuming that the length of the independent intake passage is l, the sectional area of the passage is f, the cylinder volume is Vm, and the sound speed is a, the natural frequency ν of the independent intake passage is And the opening period of the intake valve expressed by the crank angle is θ
Then, the inertia tuning rotation speed Ni by the independent intake passage becomes Ni = θ · ν / 6 since the tuning condition is (60 / Ni) · (θ / 360) = 1 / ν. Accordingly, as the independent intake passage is shortened, the inertial tuning rotational speed Ni increases, and the inertial tuning rotational speed Ni is set to be higher than the allowable maximum rotational speed Nmax of the engine (Ni> Nmax). The length of the independent intake passages 5a to 5f can be reduced as compared with the case where the inertia effect can be provided in the range (Ni> Nmax). Further, by such setting, the resonance natural frequency of the resonance system can be increased without being influenced by the natural frequency of the independent intake passage, and a resonance effect in a high-speed range can be obtained.

Further, since the communication passage 14 is connected to a substantially middle portion of the range corresponding to the cylinder arrangement portion in the middle of the collective passages 6 and 7, the imbalance of the resonance supercharging action for each cylinder is reduced even at a high speed range. The resonance effect is effectively exhibited.
Therefore, the characteristic of the engine output torque in the case of such a passage configuration is shown by a solid line A in FIG. 2, and when the collective passages 6 and 7 are communicated at one end side in the cylinder arrangement direction (two-dot chain line C ), The output torque in the high-speed range can be increased.

When the on-off valve 15 of the communication passage 14 is closed, the collecting passages 6 and 7 are in communication with each other via the passage portions 8 and 9, the communication passage is elongated, and the natural frequency of the resonance system is reduced. As shown by the broken line B in FIG.
The engine output torque is increased in a lower speed region than when 15 is opened.

FIG. 3 shows another embodiment of the present invention. In this embodiment, the collective passage 60 for each of the independent intake passages 5a to 5c on one bank 1 and the independent passages 5d to 5f for the other bank are provided. The collecting passage 70 is partitioned by a partition wall 16, the upstream side of each of the collecting passages 60 and 70 is connected to the common intake passage 10, and 3 corresponding to the independent intake passages 5 a to 5 c and 5 d to 5 f.
Communication passage 1 between the two collecting passages 60 and 70
4a, 14b, and 14c are provided. Further, as shown in this figure, the collecting passages 60 and 70 may have an enlarged shape having a certain volume.

Also in the case of this embodiment, each of the independent intake passages 5a to 5f
It is formed short so that its inertia tuning rotational speed is higher than the allowable rotational speed of the engine. And the above independent intake passage
5a to 5c and 5d to 5f, collective passages 60 and 70, and each communication passage 14
a, 14b, 14c form a resonance system to obtain a resonance supercharging action in a high speed range, in which case the communication paths 14a, 14b,
By arranging 14c, the resonance supercharging effect is effectively applied to each cylinder. Also in such a configuration, the communication passages 14a, 14b, 14c are provided with on-off valves 15a, 15b, 15c that open and close according to the engine speed.

In each of the above embodiments, the case where the present invention is applied to a V-type six-cylinder engine has been described. However, the present invention can be applied to other various multi-cylinder engines.

〔The invention's effect〕

As described above, according to the present invention, the independent intake passages for the respective cylinders are grouped for each group in which the cylinders in which the intake order is not continuous are in the same group, and the inertial tuning rotational speed of each independent intake passage is allowed by the engine. The number of revolutions is set to be higher than the maximum number of revolutions, and a communication passage is connected in the middle of each of the collection passages in which the above-mentioned independent intake passages are gathered for each group, thereby forming a resonance system. Since the passage is provided with an on-off valve that opens in the high-speed range and closes in the low-speed range, the resonance supercharging action can be obtained in the low-speed range and the high-speed range. In particular, in a gasoline engine that has a higher allowable maximum speed than a diesel engine, the inertia tuning speed is set to be higher than the allowable maximum speed, so that the resonance supercharging can be effectively performed in the high speed range where the on-off valve is closed. The independent intake passage can be shortened and the intake system can be made sufficiently compact while improving the engine output.

[Brief description of the drawings]

FIG. 1 is a schematic view of an intake device showing one embodiment of the present invention, and FIG.
The figure is a characteristic diagram of the engine output torque showing the resonance effect of the intake device, and FIG. 3 is a schematic diagram of the intake device showing another embodiment. 3a-3f …… Cylinder, 5a-5f …… Independent intake passage, 6,7,60,70
... Collective passage, 14, 14a to 14c ... Communication passage.

Continuation of front page (56) References JP-A-62-121828 (JP, A) JP-A-61-291720 (JP, A) JP-A-60-233313 (JP, A) (U, U) Real opening Sho 61-171830 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02B 27/00-27/02

Claims (1)

(57) [Claims] In a gasoline engine provided with an intake air amount detecting means on an upstream side of an intake passage, an intake system of the engine is divided into a plurality of groups in which cylinders whose intake order is not continuous are grouped into the same group. The independent intake passages are grouped for each group, the independent intake passages are set such that the inertia-tuned rotation speed of the passages is higher than the maximum allowable engine speed, and the independent intake passages are set for each group. In the middle of each of the collecting passages, a communication passage communicating with each of the collecting passages is connected, and the independent intake passage and the collecting passage of each of the groups and a passage connected to each of the collecting passages downstream of the intake air amount detecting means. A part and the communication path constitute a resonance system, and an on-off valve is provided in the communication path,
An intake device for an engine, wherein the on-off valve is opened in a high speed range of the engine and closed in a low speed range of the engine.