JP2552284B2 - Engine intake system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an intake system for an engine, which enhances intake charging efficiency by a dynamic effect.

(Prior Art) Conventionally, various engine intake devices have been known in which the charging efficiency is enhanced by the dynamic effect of intake air. For example, as seen in JP-A-59-565, in a V-type engine, a curved individual intake passage corresponding to a branch portion and a space corresponding to an expansion chamber communicating with the individual intake passage are provided. Some of them have an intake manifold to have an inertia supercharging effect to improve the charging efficiency. In addition, in the one disclosed in this publication, the intake system is laid out between both banks of the V-type engine to reduce the overall size.

By the way, as a method of utilizing the dynamic effect, there is a method of increasing the charging efficiency by the resonance effect in addition to the inertia effect, for example, as seen in JP-A-61-241418, in a multi-cylinder engine, The intake passage is provided with two surge tanks that communicate with the intake ports of two cylinder groups whose intake orders are not adjacent to each other, and an annular passage that connects these surge tanks with each other on the upstream side and the downstream side is formed. Some have been designed to perform resonance supercharging.

(Problems to be Solved by the Invention) In this type of intake device, it is desirable to enhance the dynamic effect by avoiding the attenuation of the pressure liquid as much as possible, but there is a problem in such attenuation of the pressure wave. It had been. That is, for example, in the device as disclosed in Japanese Patent Laid-Open No. 61-241418, two passages (surge tanks) that communicate with the intake ports of the two cylinder groups are communicated with each other on the upstream side and the downstream side, respectively. In addition, since the upstream side communication part also serves as the intake flow path, when trying to propagate the pressure wave over the entire annular passage including this upstream side communication part to give a dynamic effect, May dampen the pressure wave and adversely affect the dynamic effects.

In view of the above circumstances, the present invention provides an intake system for an engine, which can effectively exhibit the dynamic effect of intake air, and in particular, can obtain a large dynamic effect by obtaining a strong pressure wave. is there.

(Means for Solving the Problem) According to the device of the present invention, a multi-cylinder engine is divided into two cylinder groups, a first cylinder and a second cylinder, in which cylinders whose intake order is not continuous are grouped, and the cylinders are connected to an intake port of each cylinder. A first intake supply passage for supplying intake air to each cylinder of the first cylinder group, a second intake supply passage for supplying intake air to each cylinder of the second cylinder group, and both intake supply passages on both sides of the intake passage. An intake system for an engine, which is provided with an annular passage formed by communicating both sides communicating with each other, wherein a main intake passage for introducing intake air into each cylinder is provided with cylinders at both ends of a first cylinder group in the first intake supply passage. Are connected so as to open between the intake port connecting portions corresponding to the above and the intake port connecting portions corresponding to both end cylinders of the second cylinder group in the second intake supply passage.

(Operation) According to this configuration, a pressure wave that becomes a positive pressure at the end of the intake stroke is generated in the vicinity of the intake port for each of the above groups, and the pressure wave makes a full circle around the annular passage and the intake ports of the same cylinder group. A dynamic effect is obtained by acting on. Then, the communicating portions on both sides of the annular passage, which are the propagation paths of the pressure wave, are formed independently of the main intake passage that supplies the intake air, and the intake flow from the main intake passage does not pass through both the communicating portions. Since it is introduced into the intake air supply passage, the pressure wave is suppressed from being attenuated by the intake air flow.

(Embodiment) FIG. 1 shows an embodiment in which the apparatus of the present invention is applied to a V-type 6-cylinder engine. Three cylinders 3a, 3b, 3c
The other bank 2 is provided with three cylinders 3d, 3e, 3f of No. 4, No. 5, and No. 6. The ignition order (intake order) of each cylinder is, for example, the first cylinder 3a → the fourth cylinder 3d →
No. 2 cylinder 3b → No. 5 cylinder 3e → No. 3 cylinder 3c → No. 6 cylinder 3f, and each cylinder 3a to 3c in one bank 1 constitutes the first cylinder group in which the intake order is not continuous, and the other bank Each of the cylinders 3d to 3f in No. 2 constitutes a second cylinder group in which the intake order is not continuous. Intake ports 4a to 4f and exhaust ports 5a to 5f are provided in the cylinders 3a to 3f, respectively, and the intake ports 4a to 4f and the exhaust ports 5a to 5f are arranged.
Are opened and closed at predetermined timings by an intake valve and an exhaust valve (not shown).

The intake ports 4a to 4f of each cylinder are connected to a resonance annular passage 6 having no expansion chamber. This circular passage 6
Is a short branch pipe for each intake port 4a-4c of the first cylinder group.
A first intake air supply passage 6a communicating via 7a to 7c and a second intake air supply passage 6b communicating to each of the intake ports 4d to 4f of the second cylinder group via short branch pipes 7d to 7f extend on both sides. And both ends are connected to each other to form an annular shape. In other words, the annular passage 6 has, on both sides, communication portions 6c and 6d that communicate with the portions communicating with the intake ports 4a to 4c of the first cylinder group and the portions communicating with the intake ports 4d to 4f of the second cylinder group, respectively. The length of each of the communication portions 6c and 6d is longer than the length between the intake ports of the adjacent cylinders of the same cylinder group so that the pressure waves between the cylinder groups do not interfere with each other so as to weaken each other. Is also large enough.

Reference numeral 8 denotes a main intake passage for supplying intake air. The main intake passage 8 includes a common intake passage 8a for introducing intake air through an air cleaner 9 and a branch intake air branched from the common intake passage 8a. The main intake passage 8 is provided with an air flow meter 10 for detecting the intake air amount and a throttle valve 11 for adjusting the intake air amount according to an access operation.

The respective downstream ends of the branch intake passages 8b, 8c are provided between the connection portions of the intake ports 4a, 4c of the cylinders at both ends of the first cylinder group in the first intake supply passage 6a and the second intake supply passage 2a. Intake ports 4d, 4 on both ends of the cylinder group
It is connected so as to open between the connection parts for f. Therefore, the communicating portions 6c, 6 on both sides of the annular passage 6 are
d is independent of the main intake passage 8, that is, so that the intake air sent from the main intake passage 8 is supplied to each cylinder without passing through both the communication portions 6c, 6d.
Are formed. Desirably, the passage length L _{1 corresponding} to a half circumference of the annular passage 6 and the bifurcated intake passages 8 of the main intake passage 8 are provided.
The passage length L ₂ across a and 8b is formed to be substantially equal.

The operation of the apparatus of this embodiment will be described with reference to FIG.

Near each intake port of the same cylinder group in which the intake order is not continuous, for example, each intake port 4a to 4c of the first cylinder group
In the vicinity, a basic pressure oscillation (line A in FIG. 2) is generated by the operation of each cylinder of the first cylinder group, which becomes a negative pressure in the middle of each intake stroke and becomes a positive pressure at the end of the intake stroke. The pressure wave generated in the vicinity of the intake port propagates so as to be divided into both sides and circulate around the annular passage 6, respectively, and makes a round of the annular passage 6 to act on the intake ports of other cylinders in the same cylinder group. In this case, since the annular passage 6 has no expansion chamber, the pressure wave propagates without inversion.

Then, when the time period during which the pressure wave travels around the annular passage 6 and the period τ of the above-mentioned basic pressure oscillation match, that is, the entire length L of the annular passage 6 (the volume of the branch pipe, etc. is also taken into consideration). When the relation between the equivalent pipe length) and the period τ becomes τ = L / a ...... a: speed of sound, as shown by the arrow in Fig. 2, the first cylinder 3a
Pressure wave that has propagated through the annular passage 6 and that overlaps with the pressure wave that has occurred in the second cylinder 3b, and the pressure wave that has similarly propagated from the second cylinder 3b has overlapped with the pressure wave that has occurred in the third cylinder 3c. The pressure wave propagating from the cylinder 3c overlaps with the pressure wave generated in the first cylinder 3a. In this way, the pressure waves resonate between the cylinders of the first cylinder group, and the pressure vibration is intensified as indicated by the line B in FIG. Is strengthened. Due to such a resonance effect, the charging efficiency of each cylinder is improved.

Although FIG. 2 shows a basic resonance state in which one pressure wave of pressure oscillation occurring in the same cylinder group propagates so as to overlap with the next pressure wave, every other pressure wave or every other pressure wave is shown. A resonance state is obtained even when propagating so as to overlap with the pressure wave, and therefore a resonance state is obtained even at an engine speed that is an integral multiple of the engine speed at which the above-described basic resonance state is obtained. However, when divided into two cylinder groups, each group generates a pressure wave of almost opposite phase, so that the pressure waves of both groups cancel each other at an even multiple of the rotational speed at which the above-mentioned first-order resonance is obtained. To do. Therefore, what is effective is a rotational speed that is an odd multiple of the rotational speed at which the above-mentioned primary resonance is obtained.

When the pressure wave circulating in the annular passage 6 is made to have a resonance effect in this way, it is advantageous for improving the filling efficiency in the high speed region.

That is, if the annular passage 6 is not used, for example, the first passage
When a reversal pressure wave is used to exert a dynamic effect by using a pressure reversal portion as a collective portion of an intake passage communicating with each intake port of the cylinder group and an intake passage communicating with each intake port of the second cylinder group, 1/2 of basic pressure oscillation cycle
When the pressure wave reciprocally propagates in the passage between the intake port and the collecting portion at a time corresponding to, the pressure wave reflected by reversing from negative pressure to positive pressure in the collecting portion is automatically generated. A dynamic effect is obtained by acting at the end of the intake stroke of the cylinder. At this time, the period τ of pressure oscillation and the length L'of the passage are obtained.
The relationship with (equivalent pipe length) is τ / 2 = 2L '/ a .... Then, in order to satisfy this relationship in the high speed region where the cycle τ of the pressure oscillation becomes short, it is necessary to set the passage length to be considerably short, but the passage length from the intake port of each cylinder to the passage collecting portion is In addition, there is a difference in the length of the intake ports between the cylinders, and the shorter the passage length to the collecting section, the larger the difference becomes. Becomes larger and it becomes difficult to increase the overall filling effect.

On the other hand, when the annular passage 6 having no expansion chamber is used as described above, the resonance effect is obtained when the above equation is satisfied. When this equation is compared with the equation, the period τ of pressure oscillation is
Is the same, the equivalent pipe length L of the entire annular passage 6 is four times the equivalent pipe length L ′ in the case of the above expression, and the difference in the pressure wave propagation paths for each cylinder is relatively small even in the high speed region. The imbalance of the pressure wave acting on the cylinder is reduced. Therefore, even in the high speed range, the pressure wave can be applied to each cylinder almost uniformly, and the filling efficiency of each cylinder can be effectively increased.

Further, particularly according to this intake device, the intake air introduced through the main intake passage 8 is the branch intake passage of the main intake passage 8.
8b, 8c is directly supplied to each intake port, and the air flow itself is small in both side communicating portions 6c, 6d of the annular passage 6, so that the pressure wave propagating in the annular passage 6 may be attenuated by the intake flow. Suppressed. In addition, the above-mentioned communication parts 6c, 6 on both sides
Since the passage diameter, volume, length, etc. can be set to be suitable for the propagation of the pressure wave without any restriction for securing the intake air intake amount, etc., the pressure wave can also be strengthened by this.

A part of the pressure wave propagating in the annular passage 6 is also transmitted to the branch intake passages 8b, 8c of the main intake passage 8, and the circulation path of the pressure wave is also formed by the branch intake passages 8b, 8c and the annular passage 6. Therefore, as described above, the length L ₁ of the substantially half circumference of the annular passage 6 and the length L extending over both of the branch intake passages 8b and 8c are as described above.
_{If 2} and ₂ are made almost equal, resonance will occur between them and the pressure wave will be further strengthened.

The specific structure of the device of the present invention is not limited to the above embodiment,
Various changes are possible, and some examples are shown in FIGS. 3 and 4.

In the embodiment shown in FIG. 3, the passage length of the annular passage 6 is variable. That is, a short-circuit communication part 6e for short-circuiting the middle of the one-way communication part 6c between the two cylinder groups in the annular passage 6 is provided, and the short-circuit communication part 6e and the part bypassing the short-circuit communication part 6e are connected. A switching valve 12 for switching between a state in which the portion 6e is closed and the bypass portion is opened and a state in which the short-circuit communication portion 6e is opened and the bypass portion is closed are provided. According to this structure, the annular passage 6 is relatively long when the short-circuit communicating portion 6e is closed, and the annular passage 6 is opened when the short-circuit communicating portion 6e is opened.
The actual length of Therefore, the resonance effect can be enhanced in different rotational speed regions by switching the opening / closing operation of the switching valve 12 according to the engine rotational speed by the control means (not shown).

FIG. 4 shows an embodiment in which the present invention is applied to an in-line 6-cylinder engine. Also in this case, the first to third cylinders 3a to 3c whose intake order is not continuous are the first cylinder group, and the fourth to sixth cylinders 3d to 3f whose intake order are not continuous are the second cylinder group, and the first cylinder group First intake supply passage 6a leading to each intake port 4a-4c and each intake port 4d of the second group
The second intake air supply passages 6b leading to 4f extend to both sides, and the extending portions connect to each other, so that the communicating portions 6c and 6d having appropriate lengths are provided on both sides between the two cylinder groups. An annular passage 6 is formed. Also in this case, both the branch intake passages 8b, 8c of the main intake passage 8 are also
Is connected to the downstream end of the first and second intake supply passages 6a, 6b between the connection portions for the intake ports of the cylinders at both ends, so that the both-side communication portions 6c, 6d of the annular passage 6 are connected to the main intake passage 8 It is formed independently from.

(Effects of the Invention) As described above, according to the present invention, an annular structure including first and second intake supply passages for supplying intake air to two cylinder groups in which the cylinders whose intake orders are not continuous belong to the same group and both side communicating portions are connected to each other. Since the passage is provided and the dynamic effect is obtained by the pressure wave propagating through the annular passage, the filling efficiency of each cylinder can be increased. In particular, the main intake passage for supplying intake air is provided between the intake port connecting portions corresponding to both cylinders in the first intake supply passage and between the intake port connecting portions corresponding to both cylinders in the second intake supply passage. By connecting each of them, the communicating parts on both sides of the annular passage are made independent from the main intake passage, so that the pressure wave passing through the annular passage is suppressed from being attenuated by the intake flow, thereby strengthening the pressure wave and dynamically The effect can be further enhanced.

[Brief description of drawings]

FIG. 1 is a schematic view of an intake device showing an embodiment of the present invention, and FIG.
FIG. 3 is a diagram showing pressure oscillation near the intake port, and FIGS. 3 and 4 are schematic diagrams of an intake device showing different embodiments. 3a to 3c: each cylinder of the first cylinder group, 3d to 3f: second
Each cylinder in the cylinder group, 4a to 4f ... intake port, 6 ...
Annular passages, 6a, 6b ... intake air supply passages, 6c, 6d ... communication parts on both sides of the annular passage, 8 ... main intake passages.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhiro Yuzuru 3-3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Corporation (56) References JP-A-56-52522 (JP, A)

Claims (1)

(57) [Claims] 1. A multi-cylinder engine is divided into two cylinder groups, a first cylinder group and a second cylinder group, in which cylinders whose intake order is not continuous are the same group, and a first cylinder is provided in an intake passage leading to an intake port of each cylinder.
A first intake air supply passage for supplying intake air to each cylinder of the cylinder group, and a second intake air supply passage for supplying intake air to each cylinder of the second cylinder group
An intake device for an engine, which is provided with an annular passage formed of an intake air supply passage and both side communicating portions that communicate the intake air supply passage on both sides, wherein a main intake air passage for introducing intake air into each cylinder is Opening is made between the intake port connecting portions corresponding to both end cylinders of the first cylinder group in the first intake supply passage and between the intake port connecting portions corresponding to both end cylinders of the second cylinder group in the second intake supply passage. The intake system for the engine is characterized in that it is connected in this way.