JPH01317A - engine intake system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for an engine in which intake air is resonantly supercharged by a resonant intake passage without a volume expansion part.

(Prior Art) Various types of engines have been known in which the charging efficiency of the intake air taken into the cylinder combustion chamber of the engine is increased by the dynamic effect of the intake air, thereby increasing the output torque of the engine. As an example, in Japanese Patent Publication No. 60-14169, the intake passages in a multi-cylinder engine are connected to groups of cylinders in which cylinders with discontinuous intake orders (ignition orders) are grouped into the same group. The intake passage is divided into two intake passages, and each intake passage is composed of an enlarged chamber to which the upstream end of the branch part of the intake manifold is connected, and a resonance passage connected to the enlarged chamber, and the upstream end of the resonance passage. is communicated with the upstream gathering room, and the expansion room is connected to the upstream gathering room.
A switching device is provided to switch the two intake passages into a communication state or a communication cutoff state, and when the communication between the intake passages is cut off by the switching device, the negative pressure waves generated in the intake stroke of each cylinder are collected on the upstream side. It is reflected in the chamber and inverted into a positive pressure wave, and the inverted positive pressure wave exerts a resonant supercharging effect of the intake air in a relatively low rotation range. The inversion and reflection position of the pressure waves is moved closer to the intake port to increase the natural frequency of intake pressure vibrations and obtain a resonant supercharging effect in the high-speed rotation range.

Furthermore, in the method disclosed in Japanese Patent Application Laid-Open No. 56-52522, a loop is formed in the intake manifold connected to the air cleaner, so that the intake air flows in one direction within the loop, and the air is branched into the intake manifold. The connected intake pipe is attached to the manifold so as to form an acute angle with the intake flow direction in the loop, so that the intake air filling efficiency is increased by the inertia force by utilizing the intake air flow velocity in the loop. There is.

(Problem to be Solved by the Invention) However, in the former method described above, a large-volume expansion chamber is provided at the gathering part of the intake manifold branches, so the intake system becomes large and requires a large installation space. There are some problems such as needing to be used.

Therefore, in the latter technique mentioned above, we focused on forming a loop part in the intake manifold, and connected each intake port of two cylinder groups in which cylinders with non-consecutive intake orders are in the same group to a common resonance without an enlarged chamber. This resonance annular passage extends in two directions, with a portion communicating with each intake port of one cylinder group and a portion communicating with each intake port of the other cylinder group, and t1 on both sides. By forming an annular shape in which the two cylinder groups are connected to each other, and by forming the length of the communication path on both sides between the two cylinder groups to be sufficiently larger than the length between the intake ports of adjacent cylinders in the same cylinder group, the intake air of each cylinder is The positive pressure wave generated near the intake port at the end of the stroke is made to go around the resonance annular passage and act on the intake ports of the cylinders in the same cylinder group, thereby making the dynamic effect of the intake effective. It is conceivable to make the size more compact by eliminating the need for an expansion chamber for the intake air, while still maximizing the effectiveness of the air intake.

Furthermore, in addition to the resonance supercharging effect of intake air created by such an annular intake passage, it is also possible to connect the intake port of each cylinder to an intake passage without a volume expansion chamber such as a surge tank, and increase the resonance frequency of intake air in that intake passage. It is also possible to supercharge the intake air by its resonance effect by setting the length of the intake passage so as to correspond to a specific rotational speed range (for example, a low rotational speed range) of the engine.

By the way, in a fuel injection type engine that injects fuel into the engine, it is necessary to detect the amount of intake air.The detection method for this is to detect the intake negative pressure in the intake pipe of the engine, and to A system called a speed density method is well known in which the amount of intake air is indirectly calculated based on the engine speed and the fuel injection amount corresponding to the amount of intake air is determined.

However, when the above-mentioned intake device is applied to an engine equipped with this speed density type fuel injection control device, the following problems occur. That is, the above-mentioned intake device has a structure in which intake air resonates through an intake passage without a volume expansion chamber, so the volume of the intake system is small, and the level of intake pulsation in the intake passage is higher than normal.

Therefore, when detecting intake negative pressure with a pressure sensor,
For example, when the engine speed changes, the pressure waveform of the intake air changes accordingly, so the detected pressure may not correspond to the average pressure of the intake air, making it difficult to accurately detect the amount of air.

The present invention has been made in view of the above, and an object of the present invention is to provide a pressure sensor for detecting intake negative pressure in an engine intake system that performs resonance supercharging of intake air through the above-mentioned resonance intake passage. By appropriately specifying the mounting location of the pressure sensor, the change in the pressure of the intake air detected by the pressure sensor is made as small as possible, so that the intake negative pressure can be accurately detected.

(Means for solving the problem) In order to achieve this object, the solution of the present invention is to set the mounting point of the pressure sensor at the node of resonance pressure fluctuation of the intake air in the resonance intake passage downstream of the throttle valve. It is set in the section where

That is, the configuration of the present invention is an intake system for an engine in which a resonant intake passage without a volume expansion part is provided and intake air is resonantly supercharged by the resonant intake passage. In order to control this, a pressure sensor is provided to detect negative pressure in the intake pipe, and the pressure sensor is disposed at a node of resonance pressure fluctuation of the intake air in the resonance intake passage downstream of the throttle valve.

(Function) With this configuration, resonance of intake air occurs in the resonant intake passage during operation of the engine, and the resonance can supercharge the intake air.

At this time, the change in the intake pressure wave at the node of intake resonance pressure fluctuation in the resonance intake passage downstream of the throttle valve is minimized. Since a pressure sensor is installed at this location, the pressure detected by the pressure sensor corresponds to the average negative pressure of the intake negative pressure, and the average negative pressure can be detected accurately, so the operating status of the engine can be determined. It can be controlled with high precision.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows the overall configuration of an embodiment of the present invention, and 1 is a first embodiment of the present invention.
-A fuel-injected V-type six-cylinder engine having six cylinders 2a to 2f, in which the firing order of the six cylinders 2a to 2f is 1st cylinder 2a to 6th cylinder R: J2 according to the cylinder numbers.
It is set in the order of f. These six cylinders 2a to 2f are composed of three first, third, and fifth cylinders 2a, 2c, and 2e whose firing order is not consecutive, and second, fourth, and sixth cylinders 2b, 2d, and 2f, respectively. The three cylinders 2a, 2c, and 2e constituting one cylinder group are formed in order in one bank Ia arranged in a V-shape of the engine 1, and Three cylinders 2b, 2d, and 2f are formed in order in the other bank 1a.

Each of the cylinders 2a to 2f is equipped with an intake port 3 and an exhaust port (not shown), and an intake passage 4 without a volume expansion chamber such as a surge tank is connected to the intake ports 3, 3, . There is. The intake passage 4 includes an independent intake passage 5 connected to the intake port 3 of each cylinder 2a to 2f, an annular intake passage 6 as a resonant intake passage connected to the upstream end of each independent intake passage 5, and an annular intake passage 6 connected to the upstream end of each independent intake passage 5. It consists of a common intake passage 10 connected to an annular intake passage 6, and an upstream end of this common intake passage 10 communicates with an air cleaner 11. The annular intake passage 6 is connected to each cylinder 2a in the two cylinder groups.
Two communication passages 7, 7 connected to the independent intake passages 5, 5 of ~2f, and the fifth and sixth cylinders 2e of the double-speed passages 7, 7
, an upstream communication passage 8 which extends in one direction with its ends on the 2f side communicating with each other, and whose intermediate part is connected to the downstream end of the common intake passage 10; It consists of a downstream communication passage 9 that communicates the ends of the second cylinders 2a and 2b with each other and extends in the other direction, and the lengths of the upstream communication passage 8 and the downstream communication passage 9 are the same for each cylinder. In each communication passage 7 to which the independent intake passages 5 of the group are connected, the passage length between the connection points with the independent intake passages 5, 5 corresponding to two adjacent cylinders (for example, the first cylinder 2a and the third cylinder 2c) It is set longer than that. Then, in the vicinity of the intake port 3 of each cylinder 2a to 2f in a group of cylinders in which the intake order is not consecutive, a pressure oscillation of intake air that becomes a positive pressure at the end of the intake stroke of the cylinder 2a to 2f is generated, and the pressure of the pressure oscillation is After the waves are propagated around the annular intake passage 6 in two different directions in the upstream and downstream communication passages 8 and 9, and the waves have approximately gone around the annular intake passage 6, the waves are propagated around the annular intake passage 6 in two different directions in the upstream and downstream communication passages 8 and 9, and then the waves are propagated around the annular intake passage 6 in two different directions. 2a-2
By acting on the intake port 3 of f, intake air is resonantly supercharged.

Furthermore, a throttle valve 12 is disposed midway through the common intake passage 10 to adjust the amount of intake air. Furthermore, each independent intake passage 5 is provided with a fuel injection valve 13 for injecting and supplying fuel.

The operation of each of the fuel injection valves 13 is controlled by a control unit 4. The control unit 14 receives a signal of engine rotational speed (more specifically, rotational speed) and an output signal of a pressure sensor 15 that detects intake negative pressure.
The intake air amount to the engine 1 is calculated based on the intake negative pressure and engine speed detected by the engine 5, the fuel injection amount corresponding to the calculated intake air amount is determined, and the command signal is applied to each fuel Output to the injection valve 13 and each cylinder 2a
Fuel is injected and supplied to the combustion chamber within ~2d.

The pressure sensor 15 is connected to the throttle valve 12.
It is disposed approximately at the center of the downstream communication passage 9 in the downstream annular intake passage 6 . A substantially central portion of the downstream communication path 9 where the pressure sensor 15 is disposed becomes a node of resonance pressure fluctuation of intake air, as shown in FIG. That is, FIG. 2 shows the connection point A of the annular intake passage 6 in the communication passage 7 corresponding to one cylinder group with the independent intake passage 5 communicating with the central third cylinder 2c, the downstream communication passage 9 and the upstream communication passage 7. At the center point B, B' of each passage length of the side communication passage 8 and the connection point C between the independent intake passage 5 communicating with the central fourth cylinder 2d in the communication passage 7 corresponding to the other cylinder group. It shows the pressure change of intake air, and at point A or point 0, the first, third and fifth cylinders 2a, 2c, 2e (
Alternatively, the positive pressure waves generated at the end of each intake stroke of the second, fourth and sixth cylinders 2b, 2d, 2f) circulate around the annular intake passage 6 to other cylinders 2a, 2c, 2e of the same cylinder group.
(2b.

2d, 2f) at the end of the intake stroke, the intake negative pressure at the end of the intake stroke of the capacity cylinders 2a, 2c, 2e (2b, 2d, 2f) changes to the positive pressure side from the reference level, and the intake However, at points B and B', each cylinder 2a, 2c of the cylinder group on the - side
, 2e (2b, 2d, 2f) and each cylinder 2b, 2d, 2f (2a, 2c,
Since the pressure wave propagated from 2e) cancels each other out and becomes a node of pressure fluctuation, the pressure fluctuation is extremely small and is maintained at approximately the reference level. In FIG. 2, the range indicated by a thick solid line indicates a level where the level of intake negative pressure is greater on the positive pressure side than the reference level.

Therefore, in the above embodiment, basically, the throttle valve 1 is controlled by the pressure sensor 15 while the engine 1 is operating.
2. The intake negative pressure downstream of the pressure sensor 15 is detected, and the control unit 14 inputs the output signal of the pressure sensor 15. The control unit 14 indirectly calculates the intake air amount based on the detected intake negative pressure and the engine speed. A fuel injection amount corresponding to the calculated air amount is determined, a command signal corresponding to the fuel injection amount is output to each fuel injection valve 13, and fuel is injected from each fuel injection valve 13.

With the operation of the engine 1, pressure fluctuations of intake air that becomes positive pressure at the end of the intake stroke of the cylinders 2a to 2f occur near the intake ports 3 of the cylinders 2a to 2f in the cylinder group in which the intake order is not consecutive. .

The pressure waves of this pressure vibration are transmitted through the upstream and downstream communication passages 8,
9, the air is propagated so as to go around the annular intake passage 6 in two different directions, and after approximately going around the annular intake passage 6, it acts on the intake ports 3 of the other cylinders 2a to 2f of the same cylinder group, and the intake air A resonant state occurs. This resonance condition allows the intake air to be supercharged.

In that case, the annular intake passage 6 downstream of the throttle valve 12 becomes a node of resonance pressure fluctuation of intake air. The change in the intake pressure wave at the center of the downstream communication passage 9 is the smallest, but since the pressure sensor 15 is disposed at this location, the pressure sensor 1
The pressure detected by 5 corresponds to the average negative pressure of the intake negative pressure, and the average negative pressure can be detected accurately.Therefore, the intake air amount can be accurately calculated, and fuel injection control for the engine 1 can be performed with high precision. be able to.

The position of the pressure sensor 15 is not limited to the central portion of the downstream communication passage 9 in the annular intake passage 6. That is, based on the characteristics shown in FIG. 2, it may be arranged in the central portion (point B' position) of the upstream communication passage 8 in the annular intake passage 6, as shown by the imaginary line in FIG. However, this upstream communication passage 8 has dynamic pressure of intake air flowing down from the common intake passage 10, and when this is taken into account, in order to more accurately detect intake negative pressure, it is necessary to It is preferable to arrange it in the central part of the side communication path 9.

3 to 5 each show other embodiments of the present invention.

Note that the same parts as in FIG. 1 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In the embodiment shown in FIG. 3, instead of introducing the intake air from the common intake passage 10 into the annular intake passage 6 from the upstream communication passage 8 as in the above embodiment, most of the annular intake passage 6 is used to introduce the intake air. This is applied to an intake device that is independent from the air passage. That is, the downstream portion of the common intake passage 10' is bifurcated into two branches, each communicating with each communication passage 7 of the annular intake passage 6, so that the intake air is passed only near each intake port 3 of the annular intake passage 6. By supplying the air to each cylinder 2a to 2f, the upstream and downstream communication passages 8 and 9 of the annular intake passage 6 are used as pressure wave propagation rather than intake passages that are directly involved in the introduction of intake air. The annular intake passage 6 can be set to have a shape and structure suitable for resonance supercharging without being subject to restrictions for intake air circulation. The pressure sensor 15 is disposed in the central portion of the downstream communication passage 9 of the annular intake passage 6, and therefore, this embodiment can also achieve the same effects as the above embodiment.

Further, the embodiment shown in FIG. 4 has three cylinders 2'a to 2'.
The case where c is applied to the intake system of a three-cylinder engine 1' which is not divided into two cylinder groups with respect to the intake order is shown.

In this embodiment, the annular intake passage 6' has no communication passage on one side, and the upstream communication passage 8 and the downstream communication passage 9 are directly connected to each other at one end. In the intake resonance supercharging state, the three cylinders 2'a in the annular intake passage 6'
The pressure vibration node is located at a distance of approximately 1/4 of the total length of the passage starting from the part corresponding to the second cylinder 2'b on the center side of ~2'c, and the pressure sensor 15 is disposed at that part. There is. Therefore, this embodiment can also provide the same effects as those of the above embodiment.

Furthermore, the embodiment shown in FIG. 5 is applied to an intake system that performs resonance supercharging using a normal resonant intake passage instead of the annular intake passage as in the above embodiment.

That is, in this embodiment, in the V-type six-cylinder engine 1, the intake ports 3 of the cylinders 2a to 2f of each cylinder group are communicated with the resonance intake passage 16, and both resonance intake passages 113.16 are connected to the upstream end thereof. The cylinders 2a to 2a of the cylinder group are connected to each other and connected to the common intake passage 10.
The negative pressure wave generated at 2f is propagated to the upstream side of the resonant intake passage 16 corresponding to the cylinder group, and after being reversed into a positive pressure wave by reflection at the upstream end merging section, By acting on the cylinders 2a to 2f, intake air is resonantly supercharged. In this embodiment, in the intake resonance supercharging state, both resonance intake passages 16.
A node of pressure vibration occurs at the upstream end merging portion of the pressure sensor 16, and the pressure sensor 15 is disposed at this portion.

Therefore, in this embodiment as well, since the pressure sensor 15 is disposed at the node of pressure vibration during resonance supercharging of intake air, the fluctuation of the intake negative pressure detected by the pressure sensor 15 is small, and therefore the intake negative pressure is Pressure can be detected accurately.

In each of the above embodiments, the intake negative pressure is detected by the pressure sensor 15 in order to determine the amount of fuel injected into the engines 1 and 1', but the present invention is not limited to these embodiments. Of course, the present invention can also be applied to the case where intake negative pressure is detected by a pressure sensor for controlling various other operating states of the engine.

(Effects of the Invention) As explained above, according to the present invention, the installation position of the pressure sensor for detecting intake negative pressure is adjusted by adjusting the mounting position of the pressure sensor for detecting intake negative pressure in an engine in which intake air is resonantly supercharged through an intake passage without a volume expansion chamber. By setting the position downstream of the valve to the node of resonance pressure fluctuation, it is possible to detect the negative intake pressure at the point where the change in pressure waveform is minimal, even in an intake passage-type intake system where intake pressure fluctuations are large. Therefore, the intake negative pressure can be accurately detected regardless of the operating state of the engine, and the accuracy of engine operation control based on the intake negative pressure can be improved.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a schematic plan view showing the overall configuration of an intake device, and FIG. 2 is an explanatory diagram showing pressure fluctuations in an intake passage. 3 to 5 are views corresponding to FIG. 1 showing other embodiments of the present invention. 1.1'--Engine, 2 a to 2 f, 2'
a to 2' C... Cylinder, 6.6'... Annular intake passage, 12... Throttle valve, 14... Control unit, 15... Pressure sensor, 16... Resonant intake passage.

Claims (1)

[Claims] (1) An intake system for an engine that has a resonant intake passage without a volume expansion part and that resonance supercharges the intake air through the resonant intake passage, the intake system having a resonant intake passage in which the intake air inside the intake pipe is used to control a predetermined operating state of the engine. Equipped with a pressure sensor that detects negative pressure,
An intake system for an engine, wherein the pressure sensor is disposed at a node of resonance pressure fluctuation of intake air in a resonance intake passage downstream of a throttle valve.