JP2541561B2 - Engine intake system - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake device for an engine, which is designed to supercharge intake air by a resonance intake passage having no volume expansion portion.

(Prior Art) Conventionally, there have been known various ones in which the filling efficiency is increased by a dynamic effect of intake air taken into a combustion chamber in a cylinder of an engine to increase the output torque of the engine. As an example thereof, in the one disclosed in Japanese Patent Publication No. 60-14169, etc., the intake passage in a multi-cylinder engine is connected to a cylinder group in which cylinders whose intake order (ignition order) is not continuous belong to the same group. The intake passage is divided into two intake passages, and each intake passage is composed of an expansion chamber to which the upstream end of the branch portion of the intake manifold is connected and a resonance passage connected to the expansion chamber, and the upstream end of the resonance passage. Is connected to the upstream side collecting chamber, and a switching device for switching both intake passages to a communication state or a communication cutoff state is provided in the expansion chamber, and when the communication between the intake passages is cut off by the switching device, The negative pressure wave generated in the intake stroke is reflected in the upstream side collecting chamber to be inverted to the positive pressure wave, and the inverted positive pressure wave causes the resonance supercharging effect of the intake in a relatively low rotation range. On the other hand, when the intake passages are communicated with each other, the reversal reflection position of the intake pressure wave is brought closer to the intake port to increase the natural frequency of the intake pressure vibration, thereby achieving the resonance supercharging effect in the high speed rotation range. It is designed to get you.

Further, in what is disclosed in JP-A-56-52522,
A loop is formed in the intake manifold connected to the air cleaner to allow the intake air to flow in one direction in the loop, and the intake pipe branch-connected to the intake manifold has an intake flow in the loop with respect to the manifold. By installing so as to form an acute angle with the direction, the intake flow velocity in the loop is utilized, and the intake charging efficiency is increased by its inertial force.

(Problems to be Solved by the Invention) However, in the former case, since a large-volume expansion chamber is provided in the gathering portion of the intake manifold branches, the intake system becomes large, and a large installation space is required. And so on.

Therefore, in the latter technique described above, focusing on the point that a loop portion is formed in the intake manifold, the intake ports of two cylinder groups in which the cylinders whose intake orders are not consecutive are the same group are connected to a common resonance without an expansion chamber. And a portion that communicates with each intake port in one cylinder group and a portion that communicates with each intake port in the other cylinder group extend in two directions, and are connected on both sides. The cylinders connected to each other are not connected to each other, and the length of the both-side communication path between the two cylinder groups is set sufficiently larger than the length between the intake ports of the adjacent cylinders of the same cylinder group, so that 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 almost once to act on the intake ports of the cylinders in the same cylinder group, and the dynamic effect of intake is effectively exhibited. While And eliminates the need for expansion chamber of the gas can be considered to be compact size.

Furthermore, not only the intake supercharging effect of the annular intake passage but also the intake port of each cylinder is connected to an intake passage having no capacity expansion chamber such as a surge tank, and the resonance frequency of the intake air in the intake passage is connected. By setting the length of the intake passage so that the engine speed becomes a specific rotation range (for example, a low speed rotation range) of the engine, it is possible to supercharge the intake air by its resonance effect.

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

However, when the above intake device is applied to an engine equipped with this speed-density type fuel injection control device, the following problems occur. That is, in the above-described intake device, since the intake passage has no volume expansion chamber and the intake passage is resonated, the intake system has a small volume,
The level of intake pulsation in the intake passage is higher than usual. For this reason, when the intake negative pressure is detected by the pressure sensor, for example, when the engine speed changes, the pressure waveform of the intake air also changes accordingly, so the detected pressure may not correspond to the average pressure of the intake air. It becomes difficult to detect the amount of air.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an engine intake system in which resonance supercharging of intake air is performed by the resonance intake passage described above. When controlling the injection amount, by appropriately specifying the mounting location of the pressure sensor that detects the intake negative pressure, the change in the intake pressure detected by this pressure sensor is made as small as possible, The purpose is to accurately detect the negative pressure and precisely control the fuel injection amount.

(Means for Solving the Problem) In order to achieve this object, the solution means of the present invention is such that the mounting location of the pressure sensor becomes a node (node) of the resonance pressure fluctuation of the intake air in the resonance intake passage downstream of the throttle valve. It is set in the part.

That is, the configuration of the present invention has a resonance intake passage without a volume expansion portion, and an independent intake passage whose upstream end is branched and connected to the resonance intake passage and whose downstream end is connected to each cylinder of the engine. As an engine intake device that resonates and supercharges intake air by the resonance intake passage, a fuel injection valve disposed in each of the independent intake passages for injecting fuel to the engine, and a negative pressure in the intake pipe of the engine. And a control means for determining a fuel injection amount based on an output signal from the pressure sensor and controlling each of the fuel injection valves so that the fuel of the injection amount is injected. Therefore, the pressure sensor is arranged in a portion of the resonance intake passage downstream of the throttle valve, which serves as a node for the resonance pressure fluctuation of the intake air.

Further, desirably, the resonance intake passage communicates with the independent intake passages of the respective cylinders in the two cylinder groups each of which is composed of cylinders whose ignition order is not continuous, and two communication passages connected to each other at the end portions. And a portion serving as a node of the resonance pressure fluctuation of the intake air is a connecting portion between the communication passages of the two cylinder groups.

(Operation) With this configuration, the resonance of the intake air occurs in the resonance intake passage during the operation of the engine, and the intake air can be supercharged by this resonance.

Further, the negative pressure in the intake pipe of the engine is detected by the pressure sensor, the control unit determines the fuel injection amount based on the output signal from the pressure sensor, and the fuel injection valve in each independent intake passage is The fuel injection valve is controlled to inject the fuel of the above injection amount.

At the time of the resonance supercharging of the intake air, the change in the intake pressure wave is minimized in the resonance intake passage downstream of the throttle valve, which is a node of the resonance pressure fluctuation of the intake air. Further, since the pressure sensor is arranged at this portion, 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 accurately detected. The fuel injection control can be performed accurately.

(Example) Hereinafter, the Example of this invention is described based on drawing.

FIG. 1 shows the overall configuration of an embodiment of the present invention, in which 1 is a fuel injection type V-type 6 having six cylinders 1a to 1f.
In the cylinder engine, the ignition order of the 6 cylinders 2a to 2f is set to the order of the first cylinder 2a to the sixth cylinder 2f according to the cylinder number. These six cylinders 2a to 2f are the three first, third and fifth cylinders 2a, 2c and 2e whose ignition order is not continuous.
And the second, fourth and sixth cylinders 2b, 2d and 2f are respectively divided into two cylinder groups, and the three cylinders 2a, 2c and 2e which constitute one of the cylinder groups are V of the engine 1. The three cylinders 2b, 2d, 2f of the other cylinder group are sequentially formed in the other bank 1a.

Each of the cylinders 2a to 2f is provided with an intake port 3 and an exhaust port (not shown), and the intake ports 3, 3, ... Are connected to an intake passage 4 without a volume expansion part such as a surge tank.
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 connected to an upstream end of each independent intake passage 5 as a resonance intake passage, It comprises a common intake passage 10 connected to the annular intake passage 6, and the upstream end of the common intake passage 10 communicates with an air cleaner 11. The annular intake passage 6 has the independent intake passages 5 of the cylinders 2a to 2f in the two cylinder groups.
The two communication passages 7, 7 connected to 5 and the end portions of the both communication passages 7, 7 on the fifth and sixth cylinders 2e, 2f side are communicated with each other and extend in one direction, and the intermediate portion is provided with the above. The upstream side communication passage 8 to which the downstream end of the common intake passage 10 is connected, and the downstream side which communicates the ends of the first and second cylinders 2a, 2b side of both the communication passages 7, 7 and extends in the other direction. The upstream communication passage 8 and the downstream communication passage 9 are adjacent to each other in each communication passage 7 to which the independent intake passage 5 of each cylinder group is connected.
It is set to be longer than the passage length between the connection portions with the independent intake passages 5, 5 corresponding to one cylinder (for example, the first cylinder 2a and the third cylinder 2c). Then, in the vicinity of the intake port 3 of each cylinder 2a to 2f of the cylinder group whose intake order is not continuous, the cylinder 2a to
At the end of the intake stroke of 2f, the pressure oscillation of the intake air that becomes positive pressure is generated, and the pressure wave of the pressure oscillation is generated in the upstream and downstream communication passages 8,
By making the annular intake passage 6 travel around the annular intake passage 6 in two directions different from each other and making the annular intake passage 6 to make one round, by acting on the intake ports 3 of the other cylinders 2a to 2f of the same cylinder group. , Is configured to supercharge the intake air.

Further, a throttle valve 12 for adjusting the intake air amount is arranged in the middle of the common intake passage 10. Further, a fuel injection valve 13 for injecting and supplying fuel to each of the independent intake passages 5
Are arranged.

The operation of each fuel injection valve 13 is controlled by the control unit 14. The control unit 14 is supplied with an engine speed signal (specifically, a rotation speed) and an output signal of a pressure sensor 15 that detects an intake negative pressure.
The control unit 14 calculates the intake air amount into the engine 1 based on the intake negative pressure detected by the pressure sensor 15 and the engine speed, and determines the fuel injection amount corresponding to the calculated intake air amount. The command signal is output to each fuel injection valve 13 to inject and supply fuel to the combustion chamber in each cylinder 2a to 2d.

Further, the pressure sensor 15 is provided in the annular intake passage 6 downstream of the throttle valve 12 so as to connect the two cylinder groups with each other.
It is arranged at a substantially central portion of the downstream side communication passage 9, which is one of the connecting portions of 7,7. The substantially central portion of the downstream side communication passage 9 in which the pressure sensor 15 is arranged serves as a node (node) of the resonance pressure fluctuation of the intake air as shown in FIG. That is, the second
The figure shows the independent intake passage 5 communicating with the central third cylinder 2c in the communication passage 7 corresponding to one cylinder group of the annular intake passage 6.
Connection point A, the center points B and B ′ of the passage lengths of the downstream side communication passage 9 and the upstream side communication passage 8, and the fourth cylinder 2d at the center in the communication passage 7 corresponding to the other cylinder group. Shows a change in intake pressure at a connection point C with an independent intake passage 5 communicating with the first, third and fifth cylinders 2a, 2c, 2e (or second, at a point A or a point C). 4th and 6th cylinders 2b, 2d, 2
The positive pressure wave generated at the end of each intake stroke of (f) circulates in the annular intake passage 6 and the other cylinders 2a, 2c, 2e (2
b, 2d, 2f) at the end of the intake stroke, the intake negative pressure at the end of the intake stroke of each cylinder 2a, 2c, 2e (2b, 2d, 2f) changes to the positive pressure side from the reference level. , While the resonance supercharging effect of intake air is obtained, at points B and B ′, the pressure wave propagated from each cylinder 2a, 2c, 2e (2b, 2d, 2f) of one cylinder group and the other The pressure waves propagating from the cylinders 2b, 2d, 2f (2a, 2c, 2e) of the cylinder group cancel each other out and become the nodal points of the pressure fluctuations, so the pressure fluctuations are extremely small and are maintained at approximately the reference level. It will be. Incidentally, in FIG. 2, the range indicated by a thick solid line shows a level where the intake negative pressure level is larger on the positive pressure side than the reference level.

Therefore, in the above embodiment, the throttle valve 12 is basically operated by the pressure sensor 15 during the operation of the engine 1.
The intake negative pressure on the downstream side is detected, and the intake air amount is indirectly calculated based on the detected intake negative pressure and the engine speed in the control unit 14 to which the output signal of the pressure sensor 15 is input. The fuel injection amount corresponding to the determined 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 fluctuation of intake air that becomes a positive pressure at the end of the intake stroke of each of the cylinders 2a to 2f occurs in the vicinity of the intake port 3 of the cylinders 2a to 2f in the cylinder group in which the intake order is not continuous. . The pressure wave of this pressure oscillation is propagated in the upstream and downstream communication passages 8 and 9 so as to circulate in the two different directions so as to circulate in the annular intake passage 6, and the circular intake passage 6 is circulated substantially once, and then the same cylinder group It acts on the intake ports 3 of the other cylinders 2a to 2f and causes a resonance state of intake air. By this resonance state, intake air can be supercharged.

In that case, the change of the intake pressure wave in the central portion of the downstream side communication passage 9, which becomes a node of the resonance pressure fluctuation of the intake air in the annular intake passage 6 downstream of the throttle valve 12, is minimized. Therefore, the pressure detected by the pressure sensor 15 corresponds to the average negative pressure of the intake negative pressure, and the average negative pressure can be accurately detected. Therefore, the intake air amount can be accurately calculated. Therefore, the fuel injection control for the engine 1 can be accurately performed.

The position of the pressure sensor 15 is not limited to the central portion of the downstream side communication passage 9 in the annular intake passage 6. That is, based on the characteristics of FIG. 2, as shown by the phantom line in FIG. 1, the upstream side communication passage 8 in the annular intake passage 6 (the other connecting portion of the communication passages 7, 7 of the two cylinder groups). )
It may be arranged at the central portion (position B '). But,
This upstream side communication passage 8 has a dynamic pressure of the intake air flowing down from the common intake passage 10, and in consideration of this, in order to detect the intake negative pressure more accurately, the downstream side communication passage 8 as in the above embodiment. It is preferable to arrange it in the central portion of the passage 9.

3 to 5 each show another embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted.

In the embodiment shown in FIG. 3, the intake air from the common intake passage 10 is not introduced into the annular intake passage 6 from the upstream side communication passage 8 as in the above embodiment, but most of the annular intake passage 6 is introduced. It is applied to an intake device that is independent of the air passage. That is, the downstream side portion of the common intake passage 10 ′ is branched into two branches and communicates with the communication passages 7 of the annular intake passage 6, respectively, and the intake air is passed through only the vicinity of the intake ports 3 of the annular intake passage 6. By supplying to the cylinders 2a to 2f, the upstream and downstream communication passages 8 and 9 of the annular intake passage 6 are not the intake passages directly involved in the introduction of the intake air, but the propagation of the pressure wave. The annular intake passage 6 can be set to a shape structure suitable for resonance supercharging without being restricted by the intake air flow. The pressure sensor 15 is arranged in the central portion of the downstream side communication passage 9 of the annular intake passage 6, so that this embodiment can also achieve the same effects as the above embodiment.

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

In the case of this embodiment, the annular intake passage 6'does not have one communication passage, and the upstream communication passage 8 and the downstream communication passage 9 are directly connected at their one ends. In the resonance supercharging state of the intake air, the three cylinders 2'a ...
The position of a distance of about 1/4 of the entire passage length from the part corresponding to the second cylinder 2'b on the center side of 2'c is a node of pressure vibration, and the pressure sensor 15 is arranged at that part. . Therefore, also in this embodiment, the same operation and effect as the above embodiment can be obtained.

Further, the embodiment shown in FIG. 5 is applied to an intake device that performs resonance supercharging by a normal resonance intake passage instead of the annular intake passage as in the above embodiment.

That is, in this embodiment, in the v-type 6-cylinder engine 1, the intake ports 3 of the cylinders 2a to 2f of each cylinder group are respectively communicated with the resonance intake passages 16, and both resonance intake passages 16, 1 are connected.
6 merges with each other only at the upstream end and the common intake passage 10
The negative pressure wave generated in each of the cylinders 2a to 2f of the cylinder group is propagated to the upstream side of the resonance intake passage 16 corresponding to the cylinder group, and the positive pressure is generated by the reflection at the upstream end merging portion. After the pressure waves are inverted, the intake air is resonantly supercharged by acting on the other cylinders 2a to 2f of the same cylinder group. Further, in the case of this embodiment, in the resonance supercharging state of intake air, a node of pressure oscillation occurs at the upstream end confluence portion of both resonance intake passages 16, 16, and the pressure sensor 15 is arranged at this portion.

Therefore, in this embodiment as well, since the pressure sensor 15 is arranged at the portion that becomes a node of pressure oscillation 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 reduced. The pressure can be detected accurately.

(Effects of the Invention) As described above, according to the present invention, the resonance intake passage having no volume expansion portion and the independent intake passage connecting the resonance intake passage to each cylinder of the engine are provided. For an intake system of an engine designed to supercharge the intake air, a pressure sensor that detects the negative pressure of the intake air, and the fuel injection amount is determined based on the output signal of this pressure sensor. When a control means for injecting fuel is provided, the mounting position of the pressure sensor is set at a position which becomes a node of resonance pressure fluctuation downstream of the throttle valve, so that the volume expansion part becomes unnecessary and the intake system is compact. The intake negative pressure can be detected even in the intake passage type intake system in which the intake pressure fluctuation is large, but the intake negative pressure can be detected at the site where the change in the pressure waveform is the smallest. It is possible to improve the accuracy of the fuel injection control of the engine based on the intake negative pressure by accurately detecting it regardless of the operating state of the engine.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a schematic plan view showing the overall structure of an intake device, and FIG. 2 is an explanatory diagram showing pressure fluctuations in the intake passage. 3 to 5 are views corresponding to FIG. 1 showing another embodiment of the present invention. 1,1 '... Engine, 2a-2f, 2'a-2'c ... Cylinder,
5 ... Independent intake passage, 6, 6 '... Annular intake passage, 7 ...
Communication passage, 12 ... Throttle valve, 13 ... Fuel injection valve, 14 ...
… Control unit, 15 …… Pressure sensor, 16 …… Resonance intake passage.

Claims (2)

(57) [Claims] 1. A resonance intake passage having no volume expansion portion, and an independent intake passage having an upstream end branched and connected to the resonance intake passage and a downstream end connected to each cylinder of the engine. An intake device for an engine in which intake air is resonantly supercharged by an intake passage, the fuel injection valve being arranged in each of the independent intake passages for injecting fuel to the engine and a negative pressure in an intake pipe of the engine. A pressure sensor for detecting, a fuel injection amount is determined based on an output signal from the pressure sensor, and a control means for controlling each fuel injection valve so that the fuel of the injection amount is injected, An intake device for an engine, wherein the sensor is arranged at a portion of a resonance intake passage downstream of the throttle valve, which serves as a node for resonance pressure fluctuation of intake air. 2. The resonance intake passage communicates with the independent intake passages of the cylinders in the two cylinder groups each of which is composed of cylinders whose ignition order is not continuous, and is connected to each other at the end portions.
Claim 3 (1), characterized in that it has three communication passages, and the portion that serves as a node of the resonance pressure fluctuation of intake air is a connection portion between the communication passages of the two cylinder groups. Engine intake system.