JPS62101823A - Intake device for four-cylinder engine - Google Patents

Abstract

PURPOSE:To obtain a favorable intake air charging efficiency over the whole rotation area by connecting confluence parts to each other and providing a control valve on each of their branch parts to a connecting passage, in a device in which four cylinders are divided into two groups while independent intake passages for each cylinder of each of the groups are made confluent. CONSTITUTION:Cylinders 1a-1d in a four cylinder engine, are divided into a first and a second group of a cylinders of discontinuous intake strokes, and the upper course ends of independent intake passages 9a, 9d and 9b, 9c which are connected to the cylinders of each of the groups respectively, are made confluent into a first and a second confluence parts 10A, 10B. The confluence parts 10A, 10B are led to a collecting part 12 via confluent intake passages 11A, 11B respectively, and the collecting party 12 is opened to the open air via a common intake passage 13. The confluence parts 10A, 10B are connected to each other by means of a connecting passage 19, and a control valve 20 which is closed when an engine speed is below a set value while opened when it is above the set value at least under a high load, is provided in each of the branch ports 18 of the confluence parts 10A, 10B to the connecting passage 19.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is an improvement of an intake system for a four-cylinder engine that uses the dynamic effect (f!l effect) of intake air to improve output. It is related to.

(Prior Art) Conventionally, in an engine intake system, intake pressure is controlled by utilizing intake pressure vibrations occurring in the intake passage so that a positive intake pressure wave is transmitted to the intake port just before the intake valve closes. It is known that by matching the period of vibration with the opening and closing period of the intake valve, the air in which this positive pressure wave has been generated is forced into the combustion chamber by inertia, increasing the filling efficiency of the intake air. It is being Such a dynamic effect of intake is that the negative pressure wave that occurs with the start of intake in each cylinder 1G is reflected at the open end of the intake passage toward the atmosphere or volume (for example, a nurge tank, etc.), resulting in a positive pressure wave. There is an inertial effect that uses pressure waves that are returned toward the intake boat, and a resonance effect that uses the resonance of intake pressure vibrations between cylinders that do not cause intake interference.

By the way, in a multi-cylinder engine, in the cluster where cylinders with continuous intake strokes and overlapping intake valve opening periods come together, the negative pressure is maintained at a nearly constant level due to intake interference, buffering the propagation of pressure waves. Therefore, the intake pressure vibration in the intake passage of the cylinder during the intake stroke becomes a vibration in which the pressure wave propagates back and forth between the cylinder and the above-mentioned collection part, and its unique frequency is equal to the above-mentioned collection part. determined by the position of the part. Further, matching the opening/closing cycle of the intake valve and the cycle of intake pressure vibration is limited to a specific rotation range. For these reasons, the normal intake system structure cannot exhibit the above-mentioned inertial effect and resonance effect over the entire rotation range.

For this reason, conventionally, as disclosed in Japanese Utility Model Application Publication No. 59-58736, in a six-cylinder engine, each cylinder is divided into cylinder groups whose intake strokes are not continuous, and the intake system of each cylinder is divided into independent cylinder groups. The cylinder groups are configured to merge into a convergence section for each cylinder group through an independent intake passage, and the confluence section for each multi-cylinder group is converged into a convergence section on the upstream side of the confluence section by mutually independent confluence intake passages for each cylinder group. In addition to creating a resonance effect in the low rotation range in each cylinder group, the merging section of each cylinder group is used as a large volume part to create an inertia effect mainly in the high rotation range for each cylinder. Make it 1q. Further, on the upstream side of the merging portion for each cylinder group, a communication portion is provided that connects the merging portions for each cylinder group, and a communication portion is provided in the middle of the merging intake passage. By controlling opening and closing with on-off valves according to the number of rotations, the rotation range in which the resonance effect occurs can be made variable, and the intake system 1 A device has been proposed that aims to improve the output by improving the efficiency.

(Problems to be Solved by the Invention) Therefore, it is possible to improve the output by utilizing the resonance effect and inertia effect in a four-cylinder engine using the above idea. However, in the case of a four-cylinder engine, resonance in a group of cylinders whose intake strokes are not consecutive is 2 per revolution.
Since this is carried out between two cylinders with an intake valve opening/closing period of 1,000 times, an inertial effect is obtained due to the reflection and reversal of pressure waves at the convergence area where the merging intake passages of each cylinder group converge on the lower rotation side than the resonance point. However, at the resonance point, unlike in the case of a 6-cylinder engine (resonance between 3 cylinders), it becomes a negative pressure wave and acts on the negative side, reducing the intake air filling efficiency (
(See Figure 6). For this reason, it has been found that in the case of a four-cylinder engine, it is difficult to improve the output by utilizing the resonance effect.

The present invention has been made with attention to this point, and is designed to eliminate the inertia effect caused by the intake system of the cylinder group whose intake strokes are not consecutive as described above in the low rotation range, while preventing the occurrence of the negative side resonance effect as described above. By connecting the merging intake passages of each cylinder group or between the independent intake passages of each cylinder, and obtaining an inertia effect in the high rotation range by the reflection and reversal of pressure waves by this communication part, the low rotation range is improved. The purpose is to effectively exhibit the inertia effect of the intake air in both the high speed range and the high speed range, thereby improving the output over a wide range of speed.

(Means for solving the problem) In order to achieve the above object, the solving means of the present invention divides each cylinder into groups of cylinders whose intake strokes are not consecutive, and divides the intake system of each cylinder into cylinder groups that are independent of each other. The cylinder groups are configured to merge into a convergence section for each cylinder group through an independent intake passage, and the confluence section for each multi-cylinder group is converged into a convergence section upstream of the confluence section through mutually independent confluence intake passages for each cylinder group. What should I do on the premise that I will do so? In such an intake system, a communication passage is provided which branches from the middle of each of the above-mentioned combined intake passages or each of the independent intake passages and communicates with each other. Furthermore, a control valve is provided at each junction of each combined intake passage or each independent intake passage to the communication passage, which closes at least when the engine is under high load and when the engine speed is below a set value, and when the engine speed exceeds the set value. In addition, the communicating path is configured such that 1/2 of the length of the communicating path is shorter than the path length from the branching portion to the converging portion.

(Function) With the above configuration, in the present invention, at least in high load situations where high output is required, in the low engine speed range below the set value, the merging intake passages are interconnected by the communication path by the closing operation of the control valve. communication between the intake passages or between the independent intake passages is cut off.

Therefore, by appropriately setting the passage lengths of the independent intake passages and the combined intake passages to predetermined lengths, it is possible to sufficiently exert the inertia effect between each cylinder in each cylinder group and the gathering section in the low rotation range. It is possible.

On the other hand, in the high engine speed range where the engine speed exceeds the set value and negative side resonance occurs in each cylinder group, the closing operation of the control valve causes the merging intake passages or independent intake passages to communicate with each other through the communication passage. By doing so, the above-mentioned negative side resonance effect does not occur. In addition, the pressure wave reflection 1 reversal effect is 1q at the intermediate point of the communicating path, and the path length of the communicating path is 1, -'2 (path length to the intermediate point) from the branching point to the communicating path. Because the passage length is shorter than the passage length to the gathering part, the negative pressure waves generated in the intake stroke of each cylinder in the high rotation range are reflected in the communication passage 9 and reversed, becoming positive pressure waves and returning to the intake port of each cylinder due to inertia. We aim to ensure that the effects are effectively demonstrated. From the above, it is possible to increase the intake air filling and g effect over a wide rotation range from low rotation to high rotation, thereby making it possible to improve the output.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

1 to 3 show a first embodiment in which the present invention is applied to an in-line four-cylinder engine. It shows the structure. In the figure, 18 to 1d are the first to fourth cylinders formed in series in the engine body 2, and the firing order is first → third → fourth → second cylinders. . Each of the cylinders 1a to 1d has a combustion chamber 4 above the piston 3.
An intake bow 1-5 and an exhaust port 6 are opened in the combustion chamber 4, and an intake valve 7 is formed in the intake boat 5.
However, exhaust valves 8 are arranged in the exhaust port 6 to open and close each boat at predetermined timing.

The above-mentioned cylinders 1a to 1d are divided into first and second cylinder groups A and B whose intake strokes (ignition order) are not consecutive, and the first cylinder group A includes the first and fourth cylinders 1a.

1d, and the second cylinder group B consists of the second and third cylinders lb
, 1c. The downstream ends of the first and fourth independent intake passages 9a and 9d for each cylinder are connected to each intake port 5 of the first and fourth cylinders 1a and 1cl in the first cylinder details A. 1. Fourth independent intake passage 9a
, 9d are merged into a first merging portion 10A for each cylinder group. Also, the second cylinder in the second cylinder group B. Third
Cylinder lb.

The downstream ends of second and third independent intake passages 9b and 9C for each cylinder, which are also independent from each other, are connected to each intake port 5 of 1C. Third independent intake passage 9b, 9
The upstream end of c is merged into a second merging portion 10B for each cylinder group. Further, the first merging portion 10A includes a downstream end of the first merging intake passage 11A for each cylinder group, and a second merging portion 1
The downstream ends of second merging intake passages 11B for each cylinder group are connected to 0B, and the upstream ends of these first and second merging intake passages 11Δ, 11B are connected to the merging portions 10A, 10.
On the upstream side of B, the air is collected in a C collecting part 12, and the collecting part 12 is open to the atmosphere via a common intake passage 13.

Each of the independent intake passages 98 to 9d is formed to have the same diameter and the same passage length Q, and each of the merging intake passages 11A, 1
1B is also formed with the same diameter and the same passage lengths of 2. Also,
The collecting section 12 sufficiently performs 1 inversion of reflection of the pressure wave in the collecting section 12 and 1! It is formed in the volume part (surge tank) to the right of the y8 volume.

With the above configuration, each cylinder 1a to 1 (the intake system of 1 is assumed to have an effective length of the intake passage that does not interfere with intake air from other cylinders).
Passage length (01+, Q2) consisting of separate independent intake passages 98 to 9d and combined intake passages 11A and 1"lB for each cylinder group
, and each cylinder 1a to 1d and the gathering part 1
It is set to exhibit an inertial effect between the two.

Further, each of the independent intake passages 98 to 9d is connected to the engine main body 2.
extends in a direction perpendicular to the cylinder row direction, that is, laterally, and merges into the merging portions 10A and 10B for each cylinder group, respectively, and each merging portion 1
A merging intake passage 11A for each cylinder group from OA and 10B.

11B rises upward and then extends rearward parallel to the cylinder row direction, and the passage length 91 of each independent intake passage 98 to 9d is set shorter than the passage quality Q2 of each merging intake passage 11A and 11B. In order to ensure an effective length (9+ +92 >) between each of the cylinders 1a to 1d and the gathering portion 12 to exert an inertia effect in the low rotation range, it is possible to maintain a compact structure without interfering with other members. In addition, 14 is an air cleaner provided at the upstream end of the common intake passage 13, 15 is an air flow meter arranged in the common intake passage 13 and detects the amount of intake air, and 16 is an air cleaner provided at the upstream end of the common intake passage 13. Throttle valves 17 are arranged in the passages 11A and 11B and control the amount of intake air in conjunction with each other, and fuel injection valves 17 are arranged in each of the independent intake passages 98 to 9d to inject and supply fuel.

Furthermore, each of the above-mentioned merging parts 10A and IOB includes each merging part 1
Confluence part 1 via branch hole 18 branching from 0A and 10B
A communication path 19 is provided that communicates between 0A and IOB. The communication passage 19 has a passage length 03 of 1.
,,' 2 (the length to the midpoint of the communication passage 19) is shorter than the passage length 02 (that is, the passage length from the branch hole 18 to the gathering part 12) of the merging intake passages 11A and 11B (Q3/ 2<, 92), and on the higher rotation side than the rotation range where the inertia effect occurs between each of the cylinders 1a to 1d and the gathering portion 12, the pressure wave at the middle point of the communication passage 19 is set as follows. Communication passage 1 is connected to each cylinder 1a to 1d by the reflection 1 reversal action.
9 to create an inertia effect.

Two branch holes 18 are opened and closed in each of the branch holes 18, respectively. Specifically, a 7h1j control valve 20 is provided that opens and closes to substantially allow or prevent the propagation of pressure waves, and each of these control valves 2o is connected to a single valve shaft 2.
Although not shown, the opening/closing control is controlled via an actuator by a control circuit that receives the output of an operating state detection means that detects the engine operating state (engine speed and engine load). The communication between the merging section 10A and the IOB through the communication passage 19 is controlled according to the engine operating state, and is closed at least in the low rotation range below the engine speed N pQ constant 1 shift when the engine load is 9. , is configured to open in a high rotation range where the engine rotation speed exceeds a set value. The opening/closing operation of the control valve 20 in response to engine rotational failure may be performed at least during high loads that require high output, and the control valve 20 may be opened/closed at least during low loads.
may be kept open or open.

Next, to describe the operation of the above embodiment, for example, in a high load state where high output is required, each control valve 20 is closed in a low speed range where the engine speed is below a set value.
Communication between the merging portion 10A and the IOB through the communication path 19 is cut off. In this state, the first cylinder of the first cylinder group A.
Fourth cylinder 1a.

1d and 2nd Qi IF? 2nd of group I B. 3rd cylinder lb.

In 1G, the intake system includes independent intake passages 9a to 9 (1) for each cylinder and combined intake passages 11A, 1 for each cylinder group.
1B, that is, the passage from each cylinder 1a to 1d to the collecting part 12, constitutes an intake system that does not cause intake interference between the cylinders.However, this passage is long, and Q++, Q2) are relatively long. Since its unique frequency matches the opening and closing of the intake valve 7 in the low rotation range, there is an inertia effect for each cylinder 1a to 1d between each cylinder 1a to 1d and the gathering portion 12 in the low rotation range. is effectively obtained and the intake air filling efficiency is increased.

On the other hand, in a high rotation range where the engine rotation speed exceeds the set value, negative resonance occurs in the intake system for each cylinder group, but in this case, each control valve 20 opens and the communication passage 1
Since the merging portions 10A and 10B communicate with each other through 9, the above-mentioned negative side resonance effect does not occur. I tend to
In this state, a negative pressure wave generated during the intake stroke of each cylinder 1a to 1d is reflected at the intermediate point of the communication passage 19 and is inverted, and a positive pressure wave is propagated to the intake port 5 of each cylinder 1a to 1d. ht iq, and 1/'2 of the passage length p3 of the communication passage 19 is shorter than the passage length 02 of the merging intake passages 11A and 11B (the passage length from the branch hole 18 to the gathering part 12). , the length of the path used for the propagation of this negative pressure wave and its reflected wave (positive pressure wave) Q + +, Q
, /2) becomes shorter and the initial cycle of one intake pressure matches the opening/closing cycle of the intake valve 7 in the high rotation range, so the inertia effect can be effectively obtained for each cylinder 1a to 1d in the high rotation range. This increases intake air filling efficiency. Moreover, in this high rotation range, pressure waves propagating from other cylinders in the same cylinder group A or B, whose intake strokes are performed at equal intervals (every 360'), also act effectively, and Pressure propagation greatly increases intake air filling efficiency in the high rotation range.

Therefore, as shown in FIG. 6, at least at high loads, the intermediate rotation speeds at which the inertia effect in the low rotation range (shown by the solid line) and the inertia effect in the high rotation range (shown by the broken line) can be obtained. By closing the control valve 20 on the lower rotation side and opening the control valve 20 on the higher rotation side with the above-mentioned set rotation speed N1 as the boundary, a wide range from low rotation to high rotation can be achieved. Output torque can be improved over the rotation range.

Here, to explain in detail the characteristics shown in FIG. 6 above, the output peak (inertia tuning) when the control valve 20h<rJJ
The rotational speed Na (rpm) is as follows: Na=(θ, /'6>-f [where θ: intake valve effective amount clearance (deg>, f:
It is determined by the characteristic frequency (H2) of the intake system downstream of the pressure wave inversion section (that is, the intake system up to the collection section 12). Further, the rotation speed Nb (rpm) of the output valley (resonance) when the control valve 20 is closed is Nb=
60-f. Therefore, the set rotational speed N1 for opening the control valve 20 from open to open may be set within the range of Na<l'l+<Nll.

Further, the control valve 20 does not necessarily need to be opened and closed in the entire rotation range below the set rotation speed and opened in the entire rotation range above the set rotation speed, as in the embodiment. That is, depending on the structure of the intake system and the operating rotation range, the torque characteristics between closing and opening of the control valve may be reversed at the lower or higher rotation side of the rotation range shown in FIG. 6.

In such a region, it is sufficient to switch to the one with higher torque characteristics by opening or closing the control valve.

(Other Embodiments) FIGS. 4 and 5 show a second embodiment of the present invention.
Real M! The same parts as in the example are given the same reference numerals and the explanation is given in the old I8). In the first embodiment, the confluence part 10A
, 10B are communicated with each other through a communication passage 19', instead of one communication passage connecting each of the independent intake passages 98 to 9d. That is, a communication passage 19' is provided which branches off from the middle of each independent intake passage 98-9d and communicates between the independent intake passages 98-9d, and each branch hole from each independent intake passage 98-9d to the communication passage 19' is provided. 18' is provided with a control valve 20 that closes when the engine speed is below a set value and opens when the engine speed exceeds the set value, at least when the load is high.

In this example as well, as in the first example, the inertia effect is increased to 11 in the low rotation range and high rotation range at least when the load is high, so that the output can be improved in the entire rotation range. In this case, since the communication position of the communication passage 19' has been moved to the middle of each independent intake passage 98-9d, the passage length between each cylinder 1a-1d and the communication passage 19' is shorter than in the first embodiment. As a result, the inertia effect generation region in the high rotation range shifts to the high rotation side. Furthermore, in the high rotation range, pressure waves propagating from other cylinders also act effectively through the communication passage 19', further improving the intake air filling efficiency in the high rotation range. In addition, the communication path 19
′, the communication is between four completely independent intake passages 9a as in this example.
In addition to communicating with each other through one communication passage 19' between 7 and 9d, there are also first and fourth independent intake passages 9 for each cylinder l11'.
a, 9d, and the second and third independent intake passages 9b
, 9c may be communicated with each other through communication passages, which is preferable as it can sufficiently and effectively exert the inertia effect, but even if the independent intake passages of cylinders whose intake strokes are consecutive are communicated with In the communication path, the pressure wave is reflected and transformed by 10 degrees, and an inertial effect can be exerted.

(Effects of the Invention) As explained above, according to the intake system for a four-cylinder engine of the present invention, the intake system of the cylinder groups whose intake strokes are not consecutive is divided into independent intake passages for each cylinder and combined intake passages for each cylinder group. At the same time, the combined intake passages or the independent intake passages are communicated with each other by a communication passage of a predetermined length in the high rotation range at least under high load, so that the cylinder group Since the inertial effect is effectively exerted by the reflection and inversion of the pressure waves by the communication passage without causing the negative side resonance effect,
During high loads that require high output, the output can be effectively and sufficiently improved over a wide range from low rotation to high rotation.

[Brief explanation of drawings]

The drawings illustrate embodiments of the invention, and FIGS.
An example is shown, and FIGS. 1 and 2 are a perspective view and a schematic plan view showing the overall schematic configuration, respectively, and FIG. 3 is a longitudinal sectional side view of the main part. FIGS. 4 and 5 show a second embodiment, with FIG. 4 being a perspective view of its overall schematic configuration, and FIG. 5 being a schematic plan view. FIG. 6 is a diagram showing the output torque characteristics with respect to the engine rotational speed, which is increased by 1!7 according to the present invention. 18~1d...
・Cylinder, 9a to 9d...Independent intake passage, 10A...
First merging part, 10B... Second merging part, 11A... First merging intake passage, 11B... Second merging intake passage, 12
...Gathering part, 13...Common intake passage, 18.18'
... Branch hole, 19.19'... Communication path, 20...
Control valve, A...first cylinder group, B...second cylinder group. :J Knee Engine Rounds

Claims (1)

[Claims] (1) Each cylinder is divided into cylinder groups whose intake strokes are not continuous, and the intake system of each cylinder is merged into the confluence section of each cylinder group with an independent intake passage for each cylinder, and the confluence of each cylinder group is In an intake system for a four-cylinder engine, in which the sections are arranged in merging intake passages for each cylinder group that are independent of each other, and are assembled into a gathering part upstream of the merging part, from the middle of each of the merging intake passages or each independent intake passage. A communication passage that branches out and communicates with each other is provided, and each branch part of each combined intake passage or each independent intake passage to the communication passage is closed at least when the load is high and when the engine speed is below a set value. A four-cylinder engine characterized in that a control valve is provided that opens when the above-mentioned condition is exceeded, and the communicating passage is set so that 1/2 of the passage length is shorter than the passage length from the branching part to the gathering part. Intake device.