JP2771175B2 - 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 effect in the high-speed range is obtained by the inertia effect of the independent intake passage for each cylinder as in the above intake device, it is necessary to have the inertia effect in the practical rotation speed range even in the high-speed range. Therefore, it is necessary to form the independent intake passage to be somewhat longer 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 passages are provided for each of the cylinders, it is difficult to make the intake system compact if the individual intake passages are formed to be long.

In addition, when the intake system is divided into two groups as described above, in addition to the inertial effect of the independent intake passage, resonance including a group of independent intake passages for each group and a passage portion communicating with the upstream side thereof is also included. Although a resonance effect due to the resonance of pressure waves in the system can be expected, if the independent intake passage is formed long, the length of the communication part between cylinders becomes extremely short in order to have a resonance effect at high speed range. Therefore, the effect of dividing the intake system into two groups is weak, and the natural frequency of the resonance system cannot be sufficiently increased due to the natural frequency of the independent intake passage. For these reasons, none of the conventionally known ones can effectively obtain a resonance effect near the maximum allowable rotation speed, particularly in a gasoline engine having a maximum allowable rotation speed higher than that of a diesel engine. .

The present invention has been made in view of the above circumstances, and has made it possible to shorten the independent intake passage for each cylinder to make the intake system compact, and to increase the engine output by the resonance effect particularly in a high-speed region near the maximum allowable engine speed of a gasoline engine. It is intended to provide an intake device for an engine that can be used.

[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. Each group is divided into independent intake passages for the respective cylinders, and the independent intake passages for the respective cylinders are collected for each group. In addition to forming a resonance system for each group, the independent intake passage is set so that the inertial tuning rotation speed through this passage is higher than the maximum allowable rotation speed of the engine, and the resonance system is set in resonance with its shortest path. The tuning speed Nr is set so as to satisfy 0.7 Nmax <Nr <1.2 Nmax with respect to the maximum allowable speed Nmax of the engine.

[Action]

According to the above configuration, by setting the inertial tuning rotational speed of the independent intake passage to the above-described setting, the independent intake passage becomes sufficiently short.Also, by this setting, the inertia effect of the independent intake passage is not relied on. By setting the resonance tuning speed Nr of the system as described above, in the gasoline engine, a resonance supercharging effect can be effectively obtained in a high speed region near the allowable maximum speed Nmax of the engine, as described in detail later.

〔Example〕

FIG. 1 shows an embodiment in which the apparatus of the present invention is applied to a V-type 6-cylinder engine. In FIG. Three cylinders 3a, 3b, 3c are provided, and the other bank 2 is numbered 4,
No. 5 and No. 6 cylinders 3d, 3e, 3f are provided. Each of the cylinders 3a to 3f is provided with an intake port 4a to 4f and an exhaust port (not shown), and these ports are opened and closed at predetermined timing by intake and exhaust valves (not shown). The intake order (ignition order) of the cylinders 3a to 3f is as follows: 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 2
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 includes one bank 1 group (first group) and the other bank 2 Side group (second group). Each of the independent intake passages 5a to 5c for each cylinder connected to each of the intake ports 4a to 4c of the first group and each independent intake passage for each cylinder connected to each of the intake ports 4d to 4f of the second group. 5d to 5f are gathered for each group, that is, the respective upstream ends of the independent intake passages 5a to 5c are connected to the collecting part 6 on the first group side, and the respective upstream ends of the independent intake passages 5d to 5f. Are connected to the collecting unit 7 on the second group side. Passages 8, 9 constituting an upstream communication part are connected to one end sides of the grouped collecting portions 6, 7, and the respective passages 8, 9 are communicated with each other on the upstream end side.
The common intake passage 10 is connected to this communication point. Further, a downstream communication path 11 is connected to the other end of each of the collecting portions 6 and 7. In the common intake passage 10, an air cleaner 12, an air flow meter 13, and a throttle valve 14 are arranged in this order from the upstream side.

A resonance system is configured for each of the groups on the downstream side of the air flow meter 13 (intake air amount detecting means). In the present embodiment, resonance is caused by the independent intake passages 5a to 5c and 5d to 5f in each group and the passages 8, 9 and the downstream communication passage 11 that constitute the communicating portion between the collecting portions 6, 7 and the collecting portions 6, 7. The system is configured. In this resonance system, the passages 8, 9
The upstream communication portion and the downstream communication passage 11 may be formed to have the same length, but for example, the length of the two-side communication portion may be reduced by shortening the length of the downstream communication passage 11. It may be different. As further shown in the figure,
An on-off valve 15 that opens and closes in accordance with the engine speed is provided in the downstream communication path 11, and the resonance natural vibration of the resonance system depends on whether the on-off valve 15 closes and opens the downstream communication path 11. The number may be changed. Also,
The gathering portions 6, 7 may be formed by pipes having the same cross-sectional area as the passages 8, 9, but may have a certain capacity by increasing the cross-sectional area as shown in the figure. A resonance effect is obtained.

The independent intake passages 5a to 5f in the intake device are
The inertial tuning speed Ni is the maximum permissible engine speed (maximum permissible speed in terms of engine reliability, etc.) Nmax
Ni> Nmax.... The length, capacity, etc. of the parts constituting the resonance system such that the resonance tuning rotation speed Nr in the shortest path of the resonance system is 0.7 Nmax <Nr <1.2 Nmax with respect to the maximum allowable rotation speed Nmax of the engine. Is set.

Such a setting will be described with reference to an intake system model shown in FIG. The length of the independent intake passages 5a to 5f is 1, the sectional area of this passage is f (see FIG. 2), and the cylinder volume is V
Assuming that m, the sound speed is a, and the valve opening period represented by the crank angle is θ, the inertial tuning rotational speed Ni and the natural frequency ν of the independent intake passages 5a to 5f are expressed by the following equations.

Ni ＝ θ ・ ν / 6 …… The above equation is obtained because the inertia tuning condition is (60 / Ni) · (θ / 360) = 1 / ν.

Therefore, by making the independent intake passages 5a to 5f sufficiently short, the inertia tuning rotational speed Ni obtained from the above equation becomes high enough to satisfy the condition of the above equation.

In addition, the independent intake passages 5a to 5c (5d to 5f) of each group according to the model shown in FIG. 2 and a portion including a collecting portion 6 (7) and a communicating portion therebetween (a portion surrounded by a broken line) are formed. The resonance tuning rotational frequency Nr and the resonance natural frequency νr of the resonance system to be performed are as follows.

Nr = (120 / m) x vr ... vr = (a / 4) x {1 / (Vr / F + L + D)} ... m: Number of cylinders in one group a: Sound velocity Vr: Collective with independent intake passages in one group F: Average cross-sectional area of the communicating part between the collecting parts L: Length to the middle point of the communicating part D: Average diameter of the communicating part (tube end correction) , The equivalent length of the resonance system is approximately (Vr / F + L + D)
And it is considered that the positive and negative of the pressure wave are inverted and reflected at the middle point of the communication portion, so that two reciprocations of the pressure wave correspond to one cycle, so that the resonance natural frequency νr is approximately It is obtained by the above equation. In addition, the resonance tuning speed Nr, which is the speed at which the number of suctions per second and the natural frequency νr coincide with each other, is a function of performing intake for the number of cylinders m in one group with two revolutions of the engine for each group. It is obtained by the above equation.

As described above, the resonance tuning speed Nr is determined by the specifications of the resonance system such as the capacitance Vr, the average cross-sectional area F, the length L, and the average diameter D. Therefore, the specifications of the resonance system are set such that the resonance tuning rotational speed Nr in the case of the shortest path of the resonance system falls within the range of the above-described equation. For example, in the structure shown in FIG. Independent intake passages 5a to 5f,
The specifications of the collecting portions 6, 7, the passages 8, 9, the downstream communication passage 11, and the like are set as described above.

The above-mentioned engine is equipped with an air flow meter 13
As is apparent from the provision of the gasoline engine, the gasoline engine generally has a higher allowable maximum rotational speed Nmax than the diesel engine.

According to such an intake apparatus, the resonance system is configured by dividing the intake system into two groups in which cylinders in which the intake order is not continuous are the same group. The generated pressure wave propagates from the independent intake passages 5a to 5c, 5d to 5f to the collecting portions 6, 7 and the communicating portion between the collecting portions 6, 7, and pressure vibration is generated in the portions constituting these resonance systems. Then, when the resonance natural frequency νr matches the number of suctions for each group, the pressure waves generated in the cylinders of the same group resonate, and the state in which the pressure vibration is maximized is attained. In this state, a supercharging effect by the resonance effect is obtained in a rotation speed range near the resonance tuning rotation speed Nr, and the engine output is increased.

In particular, by setting the number of resonance tunings Nr based on the shortest path of the resonance system to the range of the above expression with respect to the allowable maximum engine speed Nmax, the resonance supercharging operation is performed in a high speed region near the allowable maximum engine speed Nmax. This increases the engine output. Such an effect will be described with reference to FIG.

FIG. 3 shows the characteristics (A _{1 to} A ₅ ) of the engine output torque when the resonance tuning speed Nr is set to various values in the structure as shown in FIG. (Line B). In this figure, line A ₁
Is the characteristic when the resonance tuning speed Nr is set to the maximum allowable engine speed Nmax.
The engine output torque reaches a peak at Nmax, and the output torque is increased in a high-speed region near the peak. Also, [0.7Nmax <N
In the range of r <1.2 Nmax, even when the resonance tuning rotational speed Nr deviates from the allowable maximum rotational speed Nmax (lines A ₂ and A ₃ ), the engine output torque peaks near the allowable maximum rotational speed Nmax. Although it is lower, it is sufficiently higher than when there is no resonance effect. However, if the resonance tuning speed Nr is largely shifted to a lower speed side than the above range, the engine output torque near the permissible maximum speed Nmax becomes lower than the case where there is no resonance effect and has an opposite effect (line A ₄ ), Further, when large resonance tuning rotational speed Nr is shifted to the high-speed side than the above range, most changes is eliminated and when the engine output torque has no resonance effect at less than the allowable maximum rotational speed Nmax (line a _5). Therefore, by setting the resonance tuning speed Nr to be within the above range, the allowable maximum speed is set.
The engine output torque will be increased in the high speed region near Nmax.

In this case, by setting the inertial tuning rotational speed Ni by the independent intake passages 5a to 5f as in the above equation, the resonance tuning rotational speed is not controlled by the inertial tuning rotational speed Ni.
Nr can be sufficiently increased, and by shortening the independent intake passages 5a to 5f in this way, the resonance tuning speed Nr can be obtained while giving a certain length to the communicating portion between the collecting portions 6 and 7.
Can be increased to the above range, the effect of dividing the intake system into two groups is not impaired, and a resonance effect in a high speed region can be effectively provided.

Further, as described above, if the on-off valve 15 is provided in the downstream communication path 11 and the opening and closing of the on-off valve 15 changes the resonance natural frequency, resonance effects can be provided in different rotation speed ranges.

The specific structure of the device of the present invention is not limited to the above embodiment, but can be variously modified, and several examples are shown in FIGS. 4 to 7.

In the embodiment shown in FIG. 4, the independent intake passages 5a to 5c on one bank 1 side and the independent intake passages 5d to 5f on the other bank 2 side of the V-type six-cylinder engine are assembled, respectively. Passages 18 and 19 connected to one end sides of the portions 16 and 17 are communicated on the upstream end side, and the supply intake passage 10 is connected to this portion, and the downstream side of the upstream end communication point of the passages 18 and 19 is provided. In addition, a communication portion 21 that connects the two passages 18 and 19 is provided. The communication portion 21 is provided with an on-off valve 22 that opens and closes according to the engine speed. Further, a section of the passages 18, 19 on the downstream side from the communication portion 21 has a large sectional area.

Also in this embodiment, the inertial tuning rotational speed Ni by each of the independent intake passages 5a to 5f is set as in the above equation, and the resonant tuning rotational speed by the shortest path passing through the communication portion 21 (when the on-off valve 22 is open). By setting the resonance tuning rotational speed (Nr) of the above equation as in the above equation, a resonance supercharging action can be obtained in a high-speed region similarly to the embodiment shown in FIG. In this case, if the average cross-sectional area F in the above equation increases, the resonance natural frequency νr increases. Therefore, by increasing the cross-sectional area of the passage downstream of the communication section 21, the communication section between the collection sections is increased. To a certain length so that the effect of dividing the intake system into two groups is not impaired, and the resonance effect in the high-speed range can be effectively provided.

FIG. 5 shows an embodiment applied to a V-type four-cylinder engine. In this case as well, the cylinders 33a and 33b of one bank 31 and the cylinders 33c and 33d of the other bank 32 do not have a continuous intake order, so that the intake system is connected to one bank 31.
Divided into a group on the 31 side and a group on the other bank 32 side, independent intake passages 35a, 35b and 35c, 35d are provided for each group.
And the collecting portions 36 and 37, the passages 38 and 39, the resonance intake passage 40, the downstream communication passage 41, the on-off valve 45, and the like are configured in the same manner as the embodiment of FIG. Alternatively, a resonance system may be configured as in the embodiment of FIG.

Further, in the embodiment shown in FIG. 6, the collecting part for each group divided into one bank 1 side and the other bank 2 side.
Passages 58, 59 are connected to 56, 57, respectively, and a common intake passage 60 is connected to the upstream end side communication point, and passage-like portions 61, 62 branched from intermediate points of the passages 58, 59, respectively. Is provided. The ends of the communicating portions 61 and 62 are closed ends.

According to this embodiment, since the passage portions 61 and 62 are related to the resonance natural frequency νr as a part of the resonance system, the resonance tuning rotational speed Nr can be adjusted by the passage portions 61 and 62. Also in this case, by setting the independent intake passages 5a to 5f and the resonance system so as to satisfy the above formula, a resonance supercharging effect can be obtained effectively in a high-speed region near the allowable maximum rotational speed Nmax.

FIG. 7 shows a case where the present invention is applied to an in-line four-cylinder engine.
In this case, the first cylinder 73a and the fourth cylinder 73d in which the intake order is not continuous are in the first group, the second cylinder 73b and the third cylinder 73c.
Are the second group, and for each of these groups, the independent intake passages 75a, 75d and 75b, 75c are gathered respectively, and the upstream end side of the passages 78, 79 connected to the respective gathering portions 76, 77. The common intake passage 80 is connected to the communication location. And also in this case, a resonance system in which a resonance supercharging action is obtained in a high-speed range according to the above-described various embodiments is configured.
Passage-like portions 81 and 82 branched from passages 78 and 79 are provided. The passage-like portions 81 and 82 may be end-like as in the embodiment of FIG. 6, but as shown in FIG. 81,82
May be communicated with each other, and an opening / closing valve 83 may be provided in the communicating portion so that the resonance natural frequency can be changed by opening / closing the opening / closing valve 83. As in the other embodiments, the independent intake passages 73a to 73f and the resonance system are set so as to satisfy the above equations.

〔The invention's effect〕

As described above, the present invention relates to a gasoline engine,
Independent intake passages for each cylinder are collected for each group in which cylinders in which the intake order is not continuous are the same group,
These and a passage portion connected to each collecting portion constitute a resonance system, and the inertial tuning speed Ni
And the resonance tuning speed Nr in the shortest path of the above resonance system is set so that Ni> Nmax 0.7Namx <Nr <1.2Nmax with respect to the maximum allowable engine speed Nmax, so that each cylinder is independent. The intake passage is short enough to make the intake system more compact, and a gasoline engine, which has a higher allowable maximum speed than a diesel engine, has an effective resonance effect at high speeds near the maximum allowable speed. This can increase 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.
FIG. 3 is an explanatory diagram showing a modeled intake device for explaining the setting conditions of the independent intake passage and the resonance system, FIG. 3 is a characteristic diagram of the engine output torque when the resonance tuning speed is variously changed, and FIGS. FIG. 7 is a schematic view of an intake device showing another embodiment. 3a to 3f, 33a to 33d, 73a to 73d ... cylinder, 5a to 5f, 35a to 35d,
75a-75d …… Independent intake passage, 6,7,16,17,36,37,56,57,7
6,77 …… Assembly, 8, 9, 11, 18, 19, 21, 38, 39, 41, 58, 59, 6
1,62,78,79,81,82 …… The passage part connected to the collecting part.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-57-153924 (JP, A) JP-A-57-148024 (JP, A) (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. Independent intake passages are grouped for each group, and a resonance system for each group is constituted by the independent intake passages and the aggregation portion of each group and a passage portion connected to each aggregation portion on the downstream side of the intake air amount detecting means. At the same time, the independent intake passage is set so that the inertial tuning rotation speed through this passage is higher than the maximum allowable rotation speed of the engine, and the resonance system is configured such that the resonance tuning rotation speed Nr of the shortest path is equal to the allowable rotation speed of the engine. An intake system for an engine, wherein the maximum rotational speed Nmax is set so that 0.7Nmax <Nr <1.2Nmax.