JPS61237823A - Intake equipment for multi-cylinder engine - Google Patents

Abstract

PURPOSE:To obtain flat output torque characteristic by gathering two cylinder groups at respective intake air collecting portions through independent intake air passages, communicating both the collecting portions through a communicating passage having a control valve and controlling the control valve in accordance with an engine r.p.m. CONSTITUTION:Two cylinder groups 31, 32, having discontinuous air intake order in a six-cylinder engine have respective cylinders 21-26 including intake ports 51-56 each connected to first and second surge tanks 71, 72 through independent intake passages 61-66. The surge tanks 71, 72 join a a joint passage 9 through first and second resonance passages 81, 82. The respective resonance passages 81, 82 are provided with throttle valves 101, 102. Both the surge tanks 71, 72 communicate each other through a communicating passage 11. A control valve 12 provided with the communicating passage 11 is controlled to close at a low rotation region and open at a high rotation region. In addition, the control valve 12 is controlled to increase its opening stepwise or continuously at a region between the low rotation and high rotation regions in accordance with the increase in an engine r.p.m.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for a multi-cylinder engine, and particularly to an intake system for an engine that utilizes the resonance effect of the intake system to increase intake air filling speed.

(Prior art) In recent years, in automobile engines, attempts have been made to improve the intake air filling efficiency or output by utilizing dynamic effects such as the inertia effect and resonance effect of the intake air. Among the dynamic effects of the J5, when using the resonance effect in a multi-cylinder engine, each cylinder is divided into two cylinder groups with non-adjacent intake orders, and the cylinders in both cylinder groups are each independently controlled. Two intake air collection sections are provided that are connected via an intake passage. These intake collecting parts act as a resonant box or resonant tube that resonates with the intake image of a specific frequency, and the large positive pressure wave generated by the resonance effect pushes the intake air into the corresponding cylinder. .

However, according to the above configuration, a resonance effect can only be obtained in a specific engine rotation range where the frequency of intake air imaging matches the natural frequency of the intake collecting section determined by the volume, pipe length, etc. .

Therefore, as shown in Japanese Utility Model Application Publication No. 59-148425, for example, two intake air collection parts are merged on the upstream side, while a communication part is provided in the middle of both intake air collection parts to communicate the image collection part. , and includes a control valve that opens and closes the communication portion, and the natural frequencies of both intake air gathering portions are adjusted to two levels by opening and closing the valve.
Enabling switching to a stage is performed. In other words, if both intake collecting parts meet only at the upstream end, the pipe length becomes long and the specific number of motions becomes low, so as shown by the output torque curve a in Figure 3, the engine speed is A resonance effect is obtained in the vicinity of number 01, increasing the output torque, and when the control valve is opened to connect both intake collecting parts at the middle part, the pipe length is shortened and the specific imaging number becomes high. As already shown in the output torque curve in the figure, the resonance effect is obtained near the relatively high engine rotation speed 02, so that the output torque increases. Follow C1
Engine speed 0 where the above output torque curves a and b intersect
If the above control valve is switched from the closed state to the open state in step 3,
A resonance effect is obtained in two rotational ranges near the rotational speed 01 and near the rotational speed 02, and the range in which intake air filling efficiency or output torque is improved is expanded.

However, when using such a method, as is clear from the figure, the output torque locally decreases as shown by the arrow near the engine speed 03 at which the control valve is switched from the closed state to the open state. As a result, flat output characteristics cannot be ensured, especially in the low engine speed range, leading to problems such as poor driving performance.

(Object of the Invention) The present invention provides an air intake system in which two intake collecting parts are provided corresponding to two cylinder groups whose intake order is not adjacent to each other, and a communication part is provided which communicates both the intake collecting parts. In a multi-cylinder engine that is configured to produce a resonance effect in multiple engine speed ranges by opening and closing a control valve depending on the engine speed range, localized resonance effects caused by the resonance effect of 1q in the low engine speed range are particularly important. Preventing a decrease in output torque,
The purpose is to ensure output torque characteristics as low as possible, thereby improving running performance.

(Structure of the Invention) In order to achieve the above object, the intake system for a multi-cylinder engine according to the present invention is characterized in that it is structured as follows.

That is, two intake collecting parts are connected to two cylinder groups whose intake orders are not consecutive through independent intake passages, a communicating passage connects both intake collecting parts, and the communicating passage is connected according to the engine rotation range. In an intake system for a multi-cylinder engine that is provided with a control valve that opens and closes, a control valve opening/closing control device that causes the control valve to perform a predetermined operation is provided. This control valve opening/closing control device closes the control valve up to a first set engine speed in a low engine speed range, and closes the control valve until a second set engine speed is higher than the first set engine speed. In the above-mentioned high rotation range, the valve is opened, and between the first and second set engine rotation speeds, control is performed so that the degree of opening is increased stepwise or steplessly as the rotation speed increases. In addition, the above 1. The second set engine speed is set at a low speed side and a high speed side of the engine speed where the output torque reaches a peak due to a resonance effect when the control valve is held in a completely closed state. However, it is desirable to set these engine speeds so that the respective output i-luxes at the two engine speeds are approximately equal.

(Effects of the Invention) As described above, according to the present invention, two intake collecting parts are provided in the intake system to avoid dealing with two cylinder groups whose intake orders are not adjacent to each other, and the air flow between the two intake collecting parts is controlled. In a multi-cylinder engine intake system that is configured to produce a resonance effect in multiple engine speed ranges by shutting off or communicating with a valve, the output torque peaks due to the resonance effect obtained in the low engine speed range. Since a control valve opening/closing control device is provided that opens the control valve gradually or in stages between the low and high engine speeds, the control valve is opened gradually or in stages. In the rotation range, an extreme increase in output torque due to the resonance effect is suppressed. Therefore, localized decreases in output torque that occur between low and high engine speed ranges are prevented, and a flat output torque characteristic is obtained, thereby ensuring comfortable driving performance. .

(Example) Examples of the present invention will be described below.

As shown in FIG. 1, the engine 1 has six cylinders 21 to 2.
6, and these cylinders 21 to 26 are divided into two cylinder groups 31 with non-adjacent cylinders in the intake order as the same group.
．． It is divided into 32 groups. That is, the intake order is, for example, first cylinder 21 → fourth cylinder 24 → second cylinder 22 → fifth cylinder.
The order is cylinder 25 → third cylinder 23 → sixth cylinder 26,
In other words, the cylinders of the two cylinder groups 31 and 32 perform the intake stroke alternately without overlapping.

On the other hand, the intake device 4 that supplies intake air to each of the cylinders 21 to 26 has independent intake passages 61 to 66 whose downstream ends are connected to the intake boats 51 to 56 of each of the cylinders 21 to 26, respectively, and these independent intake passages. A first surge tank 71 to which the upstream ends of intake passages 61 to 63 corresponding to the first cylinder group 31 of the passages are connected, and intake passages 64 to 6 corresponding to the second cylinder group 32
The second surge tank 72 is connected to the upstream ends of both surge tanks 71 and 72, and the first surge tank 72 is connected to the first surge tank 72, which is provided upstream of both surge tanks 71 and 72, and whose upstream ends are joined together. A second resonance passage 81, 82 and a first second resonance passage 8+ guided from an air cleaner (not shown).
, 82, and a merging passage connected to the merging portion (branching portion) of the first. First and second throttle valves 10+ and 102 are provided which operate #il (Ml) in conjunction with the second resonance passages 81 and 82. The second surge tank 72 and the second resonance passage 82 constitute mutually independent first and second resonance spaces, and these resonance spaces have a certain unique characteristic determined by the volume of the surge tank and the length L of the resonance passage It has a frequency of vibration.

Also, the above 1. A communication passage 11 is provided between the second surge tanks 71 and 72 to communicate the two surge tanks 71 and 72, and the communication passage 11 is provided with a control valve 12 that opens and closes the passage. Furthermore, this intake device 4
is equipped with a stepping motor 13 that drives the control valve 12 to open and close, and a control unit 15 that receives an engine rotation signal X from an engine rotation sensor 14 and outputs a control signal y to the stepping motor 13. Then, when the control valve 12 is opened to open the communication passage 11, the left and right halves 111 and 112 of the communication passage 11 are connected to the first half. In place of the second resonant passages 81 and 82, the first. The first surge tank along with the second surge tanks 71 and 72. A second resonance space is formed. In this case, the length L' of each half 111, 112 of the communication channel 11 acting as a resonance tube
1 above. Since it is shorter than the length of the second resonance passages 8+ and 82, the natural frequency f' of the resonance space in this case is higher than in the above case.

Next, the operation of the above embodiment will be explained.

When the engine 1 is in operation, intake air taken in from an air cleaner (not shown) flows from the upstream confluence passage 9 of the intake device 4 to the first. are distributed into the second resonance passages 81 and 82, and are respectively introduced into the first resonance passages 81 and 82. The first throttle valve passes through the second throttle valve 101 and 102. It flows into the second surge tank 71,72. Then, this intake air passes through the independent intake passages 61 to 63 from the first surge tank 71 to the first cylinder group constituting the first cylinder group 31.
It is distributed and supplied to the third cylinders 21 to 23 and from the second surge tank 72 to the fourth to sixth cylinders 24 to 26 forming the second cylinder group 32 through independent intake passages 64 to 66. In that case, the three cylinders 21 to 21 constituting the first cylinder group 31
23, the intake order is not adjacent to each other, and the second cylinder group 32 is
Since the three cylinders 24 to 26 that form M are not adjacent in the intake order, in J3 of both cylinder groups 31 and 32, the pressure generated as the intake bows 1-51 to 53 or 54 to 55 open and close. Waves are independent intake passages 61-63 or 64-66
When propagated to the corresponding surge tank 71 or 72 through the surge tank 71 or 72, they do not cancel each other out. Intake vibration occurs in the second surge tank 71, 72 at a frequency corresponding to the engine speed. Then, the communication path 11 between the two surge tanks 71, 72 is blocked by the control valve 12, and the communication path 11 between the two surge tanks 71, 72 and the first. Second
When two mutually independent resonance spaces with a low natural frequency f are formed by the resonance passages 81 and 82, the resonance spaces and the intake vibration resonate in the low rotation range of the engine 1, and this resonance causes The resulting large positive pressure wave increases the intake air filling efficiency. Also, the control valve 12 is open and the first. The second surge tank 71, 72 and the left and right halves 11t and 112 of the communication path 11 generate two high natural frequencies r.
When the resonant space ' is formed, the resonant space resonates with the intake air vibration in the high speed range of the engine 1, and the intake air filling efficiency is increased. That is, if the on-off valve 12 is closed, an output torque characteristic A having a peak C in the low rotation range is obtained as shown in FIG. 2, and if the control valve 12 is opened, an output torque having a peak d in the high rotation range is obtained. Characteristic B is obtained. Here, in these characteristics A and B, the output torque peaks c' and d' due to the intake inertia effect within the independent intake passages 61 to 66 are generated on the rotation side of the above-mentioned peaks c and d CDa.
occurs.

Therefore, based on the signal X from the engine rotation sensor 14, the control unit 15 controls the stepping motor 1.
By outputting a control signal y to the motor 13 and rotating the motor 13 by this signal y, the control valve 12 is fully opened at a rotation speed lower than the engine rotation speed N1 where the characteristic curves A and B intersect. and the engine speed N
If it is fully opened on the higher rotation side than 1, the characteristic curve Δ
An increase in the output torque due to the resonance effect is obtained at two locations: near the beak C in the characteristic curve 8 and near the beak d in the characteristic curve 8.

However, if the switching operation of the control valve 12 from the fully open state to the fully open state is instantaneously performed at the engine speed N1, as shown in the figure, a problem occurs in which the output torque is extremely reduced at the engine speed N1. I will invite you. Therefore, in this intake device 4, the control unit 15
The following control is performed.

That is, when a signal X indicating that the engine rotation speed has increased to a predetermined engine rotation speed N3 with the control valve 12 fully open is inputted from the engine rotation sensor 14 to the control unit 15, The unit 15 outputs a control signal y for rotating the stepping motor 13 as the engine speed increases, and the control valve 12 gradually opens accordingly. Then, when the engine speed reaches N1, the control valve 12 is fully opened.

In this case, the engine speed N3 at which the control valve 12 starts to open is lower than the engine speed N2 at which the output torque reaches peak C due to the resonance effect when the control valve 12 is completely closed. The engine speed N3 is set so that the output torque at the engine speed N3 and the output torque at the engine speed N1 at which the control valve 12 is fully open are approximately the same magnitude. Therefore, the engine speed N3. Between N1, the resonance effect is suppressed by gradually opening the control valve 12, and the output torque characteristic becomes a flat curve as shown by the thick line X in the figure. This prevents the output torque peak C from occurring when the control valve 12 is instantaneously switched from the fully open state to the fully open state, and flattens the output torque characteristic particularly in the low engine speed range. As a result, comfortable driving performance is achieved.

In this embodiment, the control valve is gradually opened when the engine speed is between N3 and N1.
The opening degree of the control valve may be changed in stages.

[Brief explanation of drawings]

1 and 2 show embodiments of the present invention, with FIG. 1 being a schematic configuration diagram of an intake device, and FIG. 2 being a diagram showing control characteristics of the intake device. Further, FIG. 3 is an output l/lux characteristic diagram showing the conventional problems. 1...Engine, 31.32...Cylinder group, 4...
Intake device, 61-66...Independent intake passage, 71°72
...Intake gathering part (suji tank), 11...Communication path, 12...Control valve, 13, 14.15...Control valve opening/closing control (stepping motor, engine rotation sensor, control unit), N3...first set engine speed, N1...second set engine speed.

Claims (1)

[Claims] (1) Two groups of cylinders whose intake order is not consecutive are collected in each intake collecting part by independent intake passages, and there is also a communicating passage that communicates both the intake collecting parts, and a control valve that opens and closes the communicating passage. An intake system for a multi-cylinder engine, wherein the control valve is closed in a rotation range lower than a first set engine speed, and a second control valve is closed at a rotation speed higher than the first set engine speed. Control valve opening/closing control that opens the valve in a rotation range higher than a set engine speed, and increases the opening stepwise or steplessly as the engine speed increases between the first and second set engine speeds. An intake system for a multi-cylinder engine, characterized in that it is equipped with a device.