JPS60230509A - Suction system for engine - Google Patents

Abstract

PURPOSE:To obtain an average output improving effect in the whole operating region and set a flat torque type engine by generating an inertia supercharging effect and a resonant supercharging effect in rotation regions which are apart from each other to some extent. CONSTITUTION:The inertia synchronized number of rotation of an air column vibration system on the lower course sides of surge tanks 3, 4, which is determined by the length l1 and area A1 of the air intake passages 2a-2f which are connected to cylinders 1A-1F and divided into two cylinder groups whose suction strokes do not substantially overlap, is determined as N1, and the resonance synchronized number of rotation of an air column vibration system on the upper course sides of the surge tanks 3, 4, which is determined by the volumes of the surge tanks 3, 4 and air intake passages 2a-2f and the length l2 and area A2 of air intake passages 5, 6 up to a confluence part 7, is determined as N2. In this case, the N1 is set at 4,000-6,000r.p.m. as well as in a condition that N1-N2>=N1X0.15. Also, each area A2 is set to a smaller value than the sum of each area A1, i.e., A1X3.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an engine intake system, and in particular, the present invention relates to an engine intake system, and in particular, the invention relates to an engine intake system, and in particular, the present invention is designed to reduce flat torque so as to control the output direction by the dynamic effect of the intake system in the low to high speed operating range. This invention relates to an intake system for a type engine.

(Prior art) Conventionally, an engine cylinder and a surge tank are connected by an independent intake passage, and air column vibrations that occur in the independent intake passage while the intake valve is open are utilized. The pressure oscillations generated in the surge tank increase the amount of intake air due to the inertia effect that affects the same intake process, and the supercharging effect (so-called inertial supercharging effect) associated with the pressure oscillations in the air column vibration system downstream of the surge tank. Techniques for improving output are well known.

In addition, in a multi-cylinder engine, the intake passages connected to each cylinder are connected to one surge tank so that the intake strokes do not overlap with each other, to prevent intake interference at this gathering part, and to connect the intake passages connected to each cylinder to one surge tank. For example, an intake system that shortens the intake passage that connects the pump and utilizes the supercharging effect (hereinafter referred to as resonance supercharging effect) caused by pressure oscillations due to the influence of the air vibration system on the upstream side of the surge tank is, for example, This was proposed in Japanese Patent Publication No. 57-2892.

Therefore, the resonance supercharging effect of the air column vibration system on the upstream side of the surge tank improves charging efficiency by utilizing pressure fluctuations in the surge tank. Since the supercharging effect increases, in the prior art described above, the length of the intake passage downstream of the surge tank is shortened.

However, in an intake system that utilizes the resonance supercharging effect described above, when the length of the intake passage downstream of the surge tank is set to be relatively long so as to obtain the inertial supercharging effect in the normal rotation range, the length of the intake passage downstream of the surge tank is As the intake passage length increases, the resonance supercharging effect that uses the air column vibration system upstream of the surge tank decreases slightly, but the inertial supercharging effect that uses the air column vibration system downstream of the surge tank becomes effective. , and if both are used effectively, a larger increase in output direction can be achieved.

(Object of the Invention) In view of the above-mentioned circumstances, the present invention obtains an optimal dynamic effect from both the inertial supercharging effect and the resonance supercharging effect from low speed to high speed rotation range, and improves the overall output direction. It is an object of the present invention to provide an engine intake device that can be obtained.

(Structure of the Invention) The intake system of the present invention collects cylinder groups whose intake strokes do not substantially overlap into one surge tank through independent intake passages, and adjusts the inertia-tuned rotational speed of the air column vibration system downstream of the surge tank. N1 and the resonance tuned rotation speed of the air column vibration system on the upstream side of the surge tank is N2, then the above N1 is 40
00 to 6000 rpm, and N1-N2≧Ns X O,15+N2 X O,15
The inertial supercharging effect and the
It is characterized by the fact that the picture axis occurs in a rotating region with a certain degree of fin rotation.

(Effects of the Invention) According to the present invention, the dynamic effect of the intake system can be expressed as: the inertial tuning rotation speed N1 of the air column vibration system on the downstream side of the surge tank; and the resonant tuning rotation speed of the air column vibration system on the upstream side of the surge tank. By setting N2 to occur at a certain distance from low to high speeds, in other words, the inertia effect and resonance effect correspond to the fact that the supercharging effect is greatest within the range of ±15% of the tuned rotation speed. , the difference N1-N2 between both tuned rotation speeds is 1 of Nt.
By setting the distance to be greater than the sum of 5% and 15% of N2, the large upper region in the output direction due to the inertial supercharging effect and the resonance supercharging effect does not overlap, and the This provides an average output direction effect and allows a flat torque type engine to be set.

(Example) Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an in-line six-cylinder engine showing the basic configuration of the present invention.

The in-line six-cylinder engine 1 has the first cylinder 1A to the sixth cylinder 1.
The ignition order of F, that is, the intake stroke order is 1st→4th→2nd→5th.
→The cylinders are set in the order of 3 → 6 cylinders. And each cylinder 1
The independent intake passages 28 to 2f connected to A to 1F are each divided into two cylinder groups whose intake strokes do not substantially overlap, and are connected to the first surge tank 3 or the second surge tank 4. That is, the independent intake passages 2a, 2b of the first to third cylinders IA, IB, 1G,
2c are collected in the first surge tank 3, and the fourth to sixth surge tanks
Independent intake passages 2d, 2e, 2f for cylinder ID, 1E, IF
are collected in the second surge tank 4.

Furthermore, the first and second surge tanks 3゜4 include:
One intake passage 5, 6 is connected to the upstream side thereof, and the two intake passages 5, 6 are collectively provided to communicate with a merging passage 7.

In the above intake system, in the intake system downstream of each surge tank 3, 4, while the intake valve is open, air column vibrations occurring in the independent intake passages 2a to 2f affect the same cylinder during the same intake process. Inertial effects occur. The resonance point of the pressure vibration of the air column vibration system on the downstream side of the surge tank, that is, the inertial tuning rotation speed Ns is determined by the following approximate expression.

Nl = adt /πsxE] Weak 79. s SXZ where, 9. l is a surge tank 3 of independent intake passages 2a to 2f
．． 4 to cylinders 1A to 1F, dl is the passage diameter, B is the cylinder bore diameter, S is the piston stroke, a is the speed of sound, and l is a value of 0.5 to 0.1 depending on the valve timing and engine characteristics. is the number of characteristics set to .

In the above formula and each formula below, the engine speed is r
The speed of sound is measured in pm (revolutions per minute).

As shown in Fig. 2, the inertial effect on the engine rotation speed around the tuned rotation speed N1 is as follows: There is an effect on the output direction within the range of ±30% of N1, especially ±15% of the tuned rotation speed N1.
Within the range of , there is a significant effect on the direction of output. Moreover, this inertial supercharging effect provides good characteristics in the medium and high speed rotation range.

On the other hand, in the intake system upstream of the surge tank, the opening period of the intake valve is generally approximately 240° in terms of crank rotation angle.
Since ignition is performed in each cylinder sequentially with a 120° shift, the intake strokes of the first surge tank 3 and the second surge tank 4 alternately occur with a 120' shift of 240°, so there is no overlap in the intake strokes. At the same time, the pressure fluctuation occurs continuously, and the first surge tank 3 and the second
The pressure fluctuations with the surge tank 4 are 120° out of phase with each other. Therefore, when the pressure fluctuation in one surge tank is at its peak value, the pressure fluctuation in the other surge tank is at its trough value, causing mutual vibration in the intake passages 5 and 6 that connect both surge tanks 3.4. When the air column vibration system on the upstream side of the surge tank resonates, a large resonant supercharging effect can be obtained. The resonance point of the pressure vibration of the air column vibration system on the upstream side of the surge tank, that is, the tuned rotation speed N2, is determined by the following approximate expression.

N'2 = 10Xad2 sr king/yt V 9p
2 Here, 51,2 is the length of the intake passage 5.6 from the surge tanks 3 and 4 to the confluence, d2 is the diameter of the passage, and ■ is the volume of the surge tank and the intake passage downstream of the surge tank that communicates with it. , a is the speed of sound. However, 9.2 above
For the actual length, add the tube end correction value 2 x d2, and if there is a damping reservoir in the connection, add 4 x d2.
The value is the sum of

As shown in Figure 3, the resonance effect on the engine speed around the resonance tuning speed N2 is as follows: There is an effect on the output direction within the range of ±30% of N2, especially ±15% of the tuned rotation speed N2.
Within the range of , there is a significant effect on the direction of output. Moreover, this resonance supercharging effect provides good characteristics in the low and medium speed rotation range. Note that the tuned rotational speed N2 of the resonance supercharging effect on the upstream side of the surge tank is always lower than the tuned rotational speed Nl of the inertial supercharging effect on the downstream side of the surge tank.

Based on the characteristics of the above-mentioned inertial supercharging effect and resonance supercharging effect,
In the present invention, in order to set the engine so that average torque characteristics due to the above-mentioned supercharging effects can be obtained over a wide range of engine speeds, the tuned speeds N+ and Nz of both are set to occur at a certain distance from each other. That's what happens.

That is, the inertial tuning rotation speed N1 of the air column vibration system on the downstream side of the surge tank is set to 4000 to 6000 rpm+, and the resonance tuning rotation speed N2 of the air column vibration system on the upstream side of the surge tank is set as follows: Nt N2≧N, X O, 15+Nl! X O,1
The setting is made so that the condition No. 5 is satisfied. In this case, as mentioned above, since N2 < Nt, N2 is N
1 plus 15% of N2 and 15% of N2, but it is set in a rotation range far from the low rotation speed of G, and the supercharging effect of both is greatest in the range of 115%, so 115% of both. This is to ensure that the ranges of the two do not overlap.

As shown in Fig. 4, the output characteristics with the above settings are such that the inertial effect shown by the two-dot chain line and the resonance effect shown by the one-dot chain line occur at each tuned rotation speed Ns as an upper range in the respective frequent output directions.
, N2 is set so that the 115% ranges do not overlap, so the combined effect of both supercharging effects is as shown by the solid line.
This is a characteristic of a flat torque engine in which the engine speed does not have a large peak value with respect to the engine speed, and the output direction generally increases from the low speed range to the high speed range.

On the other hand, if the tuning speeds Nr and Nz are set too far apart, a valley where the torque decreases will occur between these two tuning speeds Nr and N2. It is desirable to set it so that the following conditions are satisfied: Ns Nz ≧N, X O, 3+N2 X 0.3.

The length 9J1 of the independent intake passage downstream of the surge tank 3.4, which corresponds to the setting range (4000 to 600 Oram) of the tuned rotation speed N1 of the air column vibration system downstream of the surge tank, is approximately 3
00 to 600 mn+, and this inertia tuning rotation speed Ns
In order to increase the rotational speed when setting the resonance tuning rotational speed N2 for , the passage diameter d2, that is, the passage area A2 may be increased, but if the passage is made short and wooden, pressure fluctuations will be reduced and the resonance effect will be lowered, so the intake passage area A2 upstream of the surge tank 3. The sum of the passage areas A1 of the downstream intake passages 2a to 2f communicating with the tanks 3 and 4 3×A
It is set to a value smaller than 1.

Further, if the upstream passage area A2 is too narrow, passage resistance increases and pressure fluctuations are attenuated, so it is desirable to set the upstream passage area A2 larger than the downstream passage area A1. That is, it is made to satisfy A*<Az≦3×A1.

In Fig. 1, the intake passages 5 and 6 on the upstream side of the surge tank 3.4 are arranged to merge, but even if these upstream ends are open to an air cleaner, etc., the intake passages 5 and 6 on the upstream side of the surge tank 3. When tuned to the resonance point of the column vibration system,
A resonance supercharging effect is obtained, and the intake passage length fl,2 in this case is the distance from the surge tank 3.4 to the open end, that is, the part where there is no substantial pressure fluctuation.

In addition, in the case of an 8-cylinder engine, if the intake valve opening period is 240 degrees, the vibration phenomenon in each surge tank will not be continuous, and the resonance supercharging effect will be small. In this case, the valve opening period may be set short, and in this case, the same resonance supercharging effect as above can be obtained, so the resonance tuning speed N2 is set to be a certain distance from the inertia tuning speed Nl as in the above condition. However, the same effect on the output direction as in FIG. 4 can be obtained. The approximate expression for determining the resonance tuning rotation speed N2 in the case of eight cylinders is as follows. Moreover, the relationship between the passage area A1 upstream of the surge tank and the passage area A2 downstream is AI < A2 ≦ 4×8! The purpose is to satisfy the following.

As mentioned above, the end of the intake passage upstream of the surge tank may be an air cleaner or a damping reservoir, so the present invention can also be applied to three or four cylinders that communicate with a single surge tank.

However, in the case of a four-cylinder engine, it is important to set the opening timings of the intake valves of the joint cylinders without substantially overlapping each other.

Furthermore, the approximate formula for calculating the resonance tuning rotation speed N2 described above is:
In the region close to the inertia-tuned rotation speed N1, the intake passages 5 and 6 become shorter and thicker, so they become affected by pressure fluctuations due to inertia effect, reducing the accuracy of the approximation formula. In the region where the upper limit of the number N2 is set, the influence of the inertial tuning rotational speed NK is reduced as it is far away from it, so the approximate expression holds true with high accuracy.

Next, more specific embodiments will be described. Fifth
The figure is an overall front view showing a six-cylinder V-type engine in partial section, and FIG. 6 is a cross-sectional plan view taken along the line Vl--Vl in FIG. 5.

The 6-cylinder V-type engine 10 has a first cylinder head 12a and a second cylinder head 12b arranged at an angle on a cylinder block 11, and has a first 3.5 cylinder 13A', a first cylinder head 12a and a second cylinder head 12b.
a first bank 14 having 13C and 13E;
．． A second bank 15 having six cylinders 13B, 13D, '13F is formed at an angle to each other. V above
The ignition order, that is, the intake stroke order of the 6-cylinder engine 10 is the order of 1st → 2nd → 3rd → 4th → 5th → 6th cylinder. Therefore,
In the first and second banks 14, 15, the intake order of each cylinder is not consecutive, and there is no overlap in the intake strokes.

The intake passage 16 that supplies intake air to each of the cylinders 13A to 13F of the first and second banks 14.15 on both sides is arranged to extend in the front-back direction in the upper part between the banks 14.15 on both sides, and is integrated into the right and left sides. It has first and second surge tanks 17 and 18 formed in the same direction. This surge tank 17.18
and each intake port 1 of the first and second bank 14.15
9 and the first and second intake pipes 2OA, 20B
is the first on the left under the surge tank 17.18.
A first boat whose downstream end is connected to the intake boat 19 of the bank 14
An intersection 21a of the downstream part of the intake ll7R20A,
Intersection 21b of the downstream portion of the second intake pipe 20B whose downstream end is connected to the intake boat 19 of the second bank 15 on the right side
intersect with each other, the upstream sides of the crossing parts 21a and 21b are bent into a U-shape, and the upstream end of the 0-shaped part 22a of the first intake pipe 20Δ is connected from the right side to the first surge located on the right side. It is connected to the tank 17, and the upstream end of the 0-shaped portion 22b of the second intake pipe 20B is connected from the left side to the second surge tank 18 located on the left side.

In addition, the first and second surge tanks 17°18 are
The interior of the entire case 23 is partitioned into independent left and right spaces by a partition wall 23a extending in the front-rear direction (parallel to the output shaft direction of the engine). The first surge tank 17 on the right side has a first intake pipe 20 connected to the first bank 14 on the left side through a communication port 17a opened on the right side surface.
The second surge tank 18 on the left is connected to the second surge tank 18 on the right through a communication port 18a opened on the left side.
h 1 K +-41t Blood and -'r 4Q 1 Q 6 ■ tE α OA D JJ! III
: & 1 An intake pipe 24 (throttle body part) on the inflow side is connected to the longitudinal rear end openings 17b and 18b of both surge tanks 17.18 from the engine output shaft direction, and the intake pipe 24 on the inflow side 24 is also provided with a partition wall extension 2'4a continuous to the partition wall 23a, and an independent passage 25.2 that communicates with both surge tanks 17.18 and supplies intake air.
It is divided into 6.

Each independent passage 25, 26 is provided with a throttle valve 27, 28, and both throttle valves 27, 28 are operated synchronously so as to open and close at the same angle.

Furthermore, an intake pipe 29 made of a flexible pipe is connected to the upstream side of the intake pipe 24 on the inflow side, and the independent passage 25. ．． 26 is extended upstream. At the terminal end of the partition wall extension 29a in the intake pipe 29 formed by this pipe, the two independent retreat passages 25 and 26 join together.

A fuel injection nozzle 30 for injecting fuel into the intake port 19 of each cylinder 13A to 13F is disposed at each intersection 21a, 21b of the intake pipes 2OA, 20B downstream of the first and second surge tanks 17,18. It is set up. In addition, in Fig. 5, 31 is an intake valve, 32 is a rocker arm,
33 is a camshaft, and 34 is a piston.

Then, the intake pipe 2 on the upstream side of the surge tank 17 and 18
4. Partition wall extension 24a formed in 29.

The length of 29a (that is, the length of the passage from the surge tank 17.18 to the confluence part (corresponding to 9J2), etc.) is set to a predetermined value based on the approximate formula so that the above-mentioned characteristics can be obtained. , Correspondingly, a resonant supercharging effect is obtained in a predetermined rotation range. Also, the intake pipe 20A on the downstream side of the surge tank 17 and 18.

The length of the passage between 20B and the intake port 19.19 is 9.l.
etc.) are also set to predetermined values based on the approximate formula to obtain the above-mentioned characteristics, and correspondingly, the inertial supercharging effect is obtained in a predetermined rotation range. .

Note that the throttle valve 27.28 is installed at a position close to the surge tank 17.18 as shown in the figure.
8. It is preferable to improve responsiveness by reducing the volume on the downstream side.

According to the embodiment described above, intake air is supplied to each cylinder of the banks 14 and 15 on both sides through the throttle valve 2 through each passage 25, 26 of the intake pipe 29, 24 upstream of the surge tank.
7.28, 1st and 2nd surge tank 17.1
The intake air flowing into 8 is connected to the communication port 17a on the side of each surge tank 17.18.

18a to the 0-shaped portions 22a and 22b of the intake pipes 2OA and 20B on both sides, respectively, and the 0-shaped portions 22a.

22b to the underside of the surge tank 17.18, and then cross each other by intersections 21a, 21b to flow from the intake port 19.19 of each cylinder head 12a, 12b to each cylinder 13A to 13F, respectively. It is supplied to

Therefore, the arrangement structure of the first and second surge tanks 17.18 and the intake pipe 24.29 on the inflow side to the surge tank 17.18 are connected to one end in the longitudinal direction from the engine output shaft direction. , the above surge tank 17.
18 and the partitioned structure in the intake pipe 24.29, it is possible to construct an intake passage with sufficient length to obtain the resonance effect of the air column vibration system upstream of the surge tank, without increasing the overall height of the engine. . Furthermore, the first and second
Intake pipe 20A downstream of surge tank 17.18.

Also in 20B, the intersection parts 21a, 21b and the ( ) character part 2
2a and 22b, the length of the intake pipes 20A and 20B downstream of the surge tanks 17 and 18 can be increased without significantly increasing the installation position of the surge tanks 17 and 18, resulting in a compact engine with a large inertial supercharging effect. This is something that can be obtained.

The length of the intake passage downstream of the surge tank 17.18 can be easily changed by replacing the 0-shaped portions 22a and 22b with ones having different lengths. The length of the intake passage can be easily changed by replacing the pipe-shaped intake pipe 29.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of an in-line six-cylinder engine showing the basic configuration of the present invention, Fig. 2 is a characteristic diagram showing the characteristics of the inertial supercharging effect in the direction of output, and Fig. 3 is the characteristic diagram of the direction of resonance supercharging effect. FIG. 4 is a characteristic diagram showing the engine output characteristics of the present invention; FIG. 5 is an overall front view showing a partial cross-section of a ■-type engine which is a specific embodiment of the present invention; FIG. The figure is Vl in Figure 5.
It is a cross-sectional plan view along the -Vl line. 1.10...Engine 1A~1F...
・Cylinder 2a to 2f...Downstream intake passage 3.4・
... Surge tank 5.6 ... Upstream intake passage 13A to 13F ... Cylinder 14.15 ... Bank 16 ... Intake passage 17 .18...Surge tank 2OA, 20B...Downstream intake pipe 24.29.
...Upstream intake pipe 25,26...Independent passages 24a, 29a...Bulkhead extension 27,28...
... Throttle valve III diagram fs2 diagram 1!3 diagram I! Figure 4 (Voluntary) Procedure... Author: Mr. Commissioner of the Patent Office October 4, 1982 2. Name of the invention Engine intake device 3. Relationship to the case of the person making the amendment Patent applicant's address Fuchu, Aki-gun, Hiroshima Prefecture Machishinchi 3-1 Name Mazda Motor Corporation [May 15, 1980 Name change process (all at once)] 4, Agent 5-2-1-6 Roppongi, Minato-ku, Tokyo Number of inventions increased by amendment 7. Subject of amendment Column 8 of "Detailed Description of the Invention" of the specification, contents of amendment 1) Page 8, line 13 of the specification

Claims (1)

[Claims] (1) An engine intake system in which a group of cylinders whose intake strokes do not substantially overlap are assembled into a single surge tank through independent intake passages, and the intake system is constructed by combining cylinders whose intake strokes do not substantially overlap into one surge tank, and which connects the surge tank to the combustion chamber in the intake system downstream of the surge tank. Let N1 be the inertia-tuned rotation speed of the air column vibration system downstream of the surge tank, which is determined by the passage length and its passage area. On the other hand, the surge tank volume in the intake system upstream of the surge tank, the intake passage volume downstream of the surge tank, and the volume from the surge tank to When the resonant tuning rotation speed of the air column vibration system on the upstream side of the surge tank, which is determined by the passage length up to the part where there is no substantial pressure fluctuation in the upstream intake passage and the passage area, is N2, the above N1 is 4000 to 6000 rpm. and set NI N2≧NIX O, 15+N2X 0
An intake system for an engine, which satisfies the conditions of 015 and is further characterized in that the area of the intake passage on the upstream side of the surge tank is set to a smaller value than the sum of the passage areas of the intake passages on the downstream side communicating with the surge tank. .