JPH01310118A - Variable intake device for v-type eight cylinder engine - Google Patents

Abstract

PURPOSE:To change the substantial length of an intake pipe so as to vary intake pulsation by communicately arranging a hollow collector between banks where intake manifolds of respective cylinders cross each other, and interlocking variable intake control valves of respective opening parts so as to control the valve for opening and closing. CONSTITUTION:A hollow collector 16 is arranged between banks where intake manifolds 12, 13 of respective cylinders cross each other so as to communicate respectively to a branch pipe 17, so that a variable intake control valve 18 to be opened and closed by interlockingly each other to each opening part thereof is provided. When the variable intake control valve 18 is closed, pressure pulsation synchronizing with the length from collectors 14, 15 to intake valves 22 is generated. On the other hand, when the valve 18 is opened, since the valve 8 is communicated to the inside of the collector 16 via the branch pipe 17, pressure pulsation is out at the position B of the control area between banks, so that pressure pulsation for synchronizing with the length from the position B to the intake valve 22 is generated with the position B serving as a mode of pressure pulsation. The characteristics of filling efficiency is thus changed in response to the operating condition of an engine, so that output torque can be improved.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a variable intake system for a type 8-cylinder engine.

<Prior Art> Conventionally, in internal combustion engines, a variable intake system has been known as a technique for achieving both an improvement in low-speed torque and an increase in output at high speeds (see, for example, Japanese Patent Laid-Open No. 19927/1983).

This variable intake system applied to a six-cylinder engine will be explained based on FIG. 19. Two collectors 2 supply intake air to three groups each of the intake manifold 1 corresponding to six cylinders. , 3 are provided. The two collectors 2 and 3 are connected by a communication pipe 4, and a variable intake control valve 5 is interposed in the center of the communication pipe 4.

The variable intake control valve 5 is controlled in the following manner according to the engine speed.

That is, when the engine is running at low speed, the variable intake control valve 5 is closed. As a result, the left and right intake passages a and b in the figure are not electrically connected, and the intake passages of the left and right banks are independent. Therefore,
The intake pipe line extends from the throttle chamber 6 to the intake valve 7, and the intake air is taken in through the long pipe line, so the intake efficiency increases due to the intake inertia effect, and torque can be improved.

On the other hand, when the engine is running at low speed, the variable intake control valve 5 is opened. As a result, the left and right intake passages a and b are electrically connected and cause intake interference with each other, so that the intake air is actually drawn from the thick and short intake pipe of the intake manifold 1, which reduces intake resistance. , output can be improved.

In a 6-cylinder engine to which such a variable intake system is applied,
By selecting the length of the intake manifold 1 upstream of the collectors 2 and 3, it is possible to generate a peak in the filling efficiency at an arbitrary rotation speed.

To explain this based on FIGS. 20 to 22, the 20th
When the variable intake control valve 10 interposed in the communication pipe 9 between the collector 8 and another collector (not shown) in the figure is closed, the inside of the collector 8 is as shown in FIG.
Pressure pulsations similar to a sine wave with three period components occur for the 720° crank. This pressure pulsation is synchronized with the intake valve opening time from when the intake valve is opened to when the intake valve is closed.
It is highly effective in improving engine filling efficiency.

Therefore, the axial torque characteristics of the engine are determined by the length of the intake manifold 11 upstream of the collector 8, as shown in FIG. (See FIG. 20), the peak of filling efficiency shifts.

By using this effect, in a six-cylinder engine, by selecting the length l of the intake manifold 11 upstream of the collector 8, it is possible to generate a peak in the charging efficiency at an arbitrary rotation speed, and the opening of the variable intake control valve 10 Torque characteristics can be changed significantly between closed and closed states.

<Problems to be Solved by the Invention> On the other hand, as shown in FIG. Second
As shown in FIG. 4, pressure pulsations of 4-cycle components occur for the 720' crank. This pressure pulsation has a small amplitude compared to a 6-cylinder engine and is not synchronized with the intake valve opening period, so even if the intake manifold length Il (see Fig. 23) upstream of the collector is changed, the charging efficiency As shown in FIG. 25, the peak does not move at all, but the peak in the low rotation range corresponding to the secondary tuned rotation range moves.

For this reason, even if the length 2 of the intake manifold 11 upstream of the collector 8 is selected, the charging efficiency characteristics cannot be significantly changed, and the torque characteristics cannot be significantly changed depending on when the variable intake control valve 10 is opened and closed. It cannot be switched (see Figure 26).

As a result, in an 8-cylinder engine to which a conventional variable intake system is applied, the torque in the low speed range can be slightly improved, but it cannot be improved significantly, and the torque in the middle speed range cannot be improved at all. there were.

Therefore, in view of the above-mentioned conventional problems, the present invention adopts a configuration in which the actual length of the intake pipe is variable, thereby changing the intake pressure pulsation and changing the intake tuning rotation speed. The object of the present invention is to provide a variable intake system for a type 8-cylinder engine that makes it possible to significantly change the torque characteristics depending on when a control valve is opened and closed.

Means for Solving the Problems〉 For this reason, the variable intake system for an 8-cylinder engine of the present invention has the following features:
A hollow collector is disposed between banks where intake manifolds provided corresponding to each of the eight cylinders intersect, and an opening provided in a part of each intake manifold is connected to the inner space of the collector. At the same time, variable intake control valves that are opened and closed in conjunction with each other are provided in the openings, and valve control means is provided that controls the opening and closing operations of the variable intake control valves in accordance with engine operating conditions.

<Operation> In such a configuration, pressure pulsations are generated in the downstream position of the central part between the banks in the intake manifold when the variable intake control valve is closed, which is synchronized with the length from the upstream end of the intake manifold to the intake valve. . Furthermore, when the variable intake control valve is opened, pressure pulsations occur that are synchronized with the length from the central position between the banks to the intake valve.

This is because the intake manifold communicates with the inside of the collector through the opening, which eliminates the pressure pulsation at the central position between the banks, making this position a pressure pulsation node, and as a result, from this position to the intake valve. This is because the length is the actual length of the intake pipe.

As a result of being able to vary the actual intake pipe length in this way, the pressure pulsation period can be varied, and the tuned rotation speed for obtaining the intake inertia effect can be changed, which can significantly change the characteristics of filling efficiency. This makes it possible to significantly change the torque characteristics between when the variable intake control valve is open and closed, making it possible to significantly improve torque in both the low-medium speed range and the high-speed range. Furthermore, since the space between the banks is used and the collector is disposed in this space, the engine does not become larger.

<Example> Embodiments of the present invention will be described below based on the drawings.

Figures 1 and 2 show a 90°■ type 8-cylinder engine, in which the ignition timing in one cylinder group consists of four cylinders each having a 180° crank difference in ignition timing. Intake manifold 12 corresponding to one cylinder
are provided, and intake manifolds 13 are provided corresponding to the four cylinders in the other cylinder group. The four intake manifolds 12 are each connected to one collector 14 disposed above the rocker cover, and the four intake manifolds 13 are each connected to the other collector 15. Near the center between the banks where the intake manifold 12 provided for one cylinder group and the intake manifold 13 provided for the other cylinder group intersect, there is a sub-collector 16 as a hollow collector of the present invention. are provided, and openings provided in a portion of each intake manifold 12, 13 are connected to the internal space of the sub-collector 16, respectively.

In this embodiment, branch pipes 17 branched from each intake manifold 12, 13 are employed as the openings,
Each branch pipe 17 opens into the sub-collector 16 internal space.

Note that each branch pipe 17 is formed to extend in the vertical direction from a position where the intake manifolds 12 and 13 intersect.

At the open end of each branch pipe 17, variable intake control valves 18 are provided, respectively, which are opened and closed in conjunction with each other.

The variable intake control valve 18 includes a butterfly-type valve body 18a, and the valve shaft of each valve body 18a is integrally connected to a single rotating shaft 19, which is rotated by a step motor 20. By moving the valve body 18a, the valve body 18a is rotated and opened/closed at the same time.

A control unit 21 is provided that includes valve control means for controlling the opening and closing operations of the variable intake control valve 18 in accordance with the engine speed.

The control unit 21 receives a rotational speed signal from an engine rotational speed sensor, outputs a control signal based on the rotational speed signal to the step motor 20, and controls the variable intake control valve 18 in the low and medium speed range of the engine. Closed and controlled to open at high speeds.

Next, the functions and effects of this configuration will be explained.

In the variable intake device of this configuration, the intake manifold 12
．． Looking at the intake pressure pulsation at position A on the downstream side of the central part between the banks in No. 13, the characteristics are as shown in FIG.

That is, when the variable intake control valve 18 is closed, pressure pulsations are generated that are synchronized with the length from the collector 14-15 to the intake valve 22, as shown by the broken line in the figure. Furthermore, when the variable intake control valve 18 is opened,
Pressure pulsations occur in synchronization with the length from position B at the center between the banks to the intake valve 22.

This is because the intake manifolds 12 and 13 communicate with the inside of the sub-collector 16 via the branch pipe 17, and as shown in FIG. is a node of pressure pulsation, and as a result, the length from position B to the intake valve becomes the actual intake pipe length.

As a result of being able to vary the actual intake pipe length in this way, the pressure pulsation period can be varied, and the tuned rotation speed for obtaining the intake inertia effect can be changed, which can significantly change the characteristics of filling efficiency. The torque characteristics can now be changed significantly between opening and closing of the variable intake control valve 18 (see Figure 5), and the torque improvement is as shown by the diagonal lines in Figure 5. Nari, 26th
The increase in torque is greater than that of the conventional collector-connected variable intake system shown by diagonal lines in the figure.

As a result, it becomes possible to significantly improve both the torque in the low-medium speed range and the high-speed range.

Furthermore, since the sub-collector 16 is arranged using the space between the banks, the engine does not become larger.

Next, another embodiment of the present invention will be described based on FIGS. 6 to 18.

That is, in the embodiment shown in FIGS. 1 and 2, each branch pipe 17 was formed to extend vertically from the intersection position of the intake manifold 12 and the intake manifold 13, but in the embodiment shown in FIGS. As shown in the figure, each branch pipe 17 may be formed to extend in an oblique direction from a position upstream of the intersection between the intake manifold 12 and the intake manifold 13. In this case, the direction of inclination of each branch pipe 17 is Each branch pipe 1
The variable intake control pulp 18 provided at the open end of the valve 7 is set to be integrally connected to a single rotating shaft 19.

Further, in the embodiments shown in FIGS. 1, 2, 6, and 7, the valve body 1 of the variable intake control valve 18
A step motor 20 is used as a driving means for the valve 8a, and the step motor 20 is controlled according to the engine speed. 18a may be opened and closed mechanically.

That is, as shown in FIG. 8, a hydraulic pressure supply port 23 is provided at one end.
a is a cylinder main body 23 provided with an atmosphere opening port 23b on the other end side, and the inside of the cylinder main body 23 is connected to the hydraulic pressure supply port 23.
a piston 24 disposed so as to partition the chamber 23A communicating with the atmosphere opening 23b, and the chamber 23B communicating with the atmosphere opening 23b; a piston rod 24a connected to the piston 24 and protruding outward from the side end wall of the chamber 23B; , and a spring 25 that always elastically urges the piston 24 toward the chamber 23A.

One end of a swing arm 27 is rotatably attached to the tip of the piston wand 24a of the hydraulic cylinder 26. The pivot shaft 1 of the valve body 18a is attached to the other end of the swing arm 27.
9 are connected, the rotation shaft 19 is rotatably supported by the fixed support portion 28.

When the engine speed is less than a predetermined value, the piston 24 is located without being pressed by hydraulic pressure, and at this time the variable intake control valve 18 is maintained in a closed state.

Then, when the engine speed increases and exceeds a predetermined value,
The piston 24 is pressed by hydraulic pressure, and the piston rod 24a moves downward in the figure, causing the swing arm 27 to swing, the rotation shaft 19 to rotate, and the variable intake control valve 18 to open.

Furthermore, in the embodiments shown in FIGS. 1, 2, 6, 7, and 8, the variable intake control valve 1 is equipped with a butterfly-type valve body 18a for each branch pipe 17.
However, as shown in FIGS. 9 and 10, a variable intake control pulp provided with a sliding valve body may be used.

That is, in FIG. 9, a sliding plate-like structure is shown in which a plurality of openings 29a are arranged side by side and match the openings of the branch pipes 17 extending vertically from the intersecting position of the intake manifolds 12 and 13 shown in FIG. A valve body 29 is provided, and this valve body 29 is disposed in the direction in which the branch pipes 17 are lined up, and set to be placed on the opening end face of the branch pipe 17. The valve body 29 is slid by an actuator 30 such as an air cylinder or a solenoid that is driven based on a rotational speed signal from a control unit, so that each opening 29a is connected to the branch pipe 17.
The branch pipe 17 is opened and closed by selectively sliding it into a position that matches the opening of the pipe and a position that does not match the opening of the pipe.

In addition, in FIG. 10, first, each intake manifold 1
A sliding plate-shaped valve body 32 is provided with an opening 31 at an upstream position of the intersection between the intake manifold 13 and the intake manifold 13, and a plurality of openings 32a that match the opening 31 are arranged side by side.
Four intake manifolds in each cylinder group 12.
A pair of valve bodies 32 are provided corresponding to the openings 13, and the pair of valve bodies 32 are arranged in the direction in which the openings are lined up, respectively set in a mounted state on the end face of the opening, and held by a holder 33 so as to be freely slidable.

This sliding plate-shaped valve body 32 is also connected to an actuator 30 such as an air cylinder or a solenoid explained in FIG.
slide the valve body 32 through its respective openings 32.
The opening 31 is opened and closed by selectively sliding the opening 31 between the opening 31 of the intake manifold 12 and 13 and the opening 31 of the intake manifold 12 and 13, respectively.

The embodiment shown in FIG. 9 has the same torque characteristics as the embodiments shown in FIGS. 1, 2, 6, 7, and 8. Actuator 3
Since it is only necessary to provide 0, the number of parts can be reduced compared to the embodiment shown in the above figure, which is advantageous in terms of cost. or,
In the embodiment shown in FIG. 10, compared to the embodiment shown in the same figure, the cost is lower, but the branch pipe 17
Since this configuration eliminates the above, it is possible to prevent an increase in ventilation resistance due to the generation of vortices by the branch pipe 17, and as shown by the solid line a in Fig. 11, the torque characteristics in the low and medium speed range are further improved. There are advantages.

Figures 12 and 13, Figures 14 and 15.

The embodiments shown in FIGS. 16 to 18 are other embodiments regarding control.

First, to explain the embodiments shown in FIGS. 12 and 13, in each of the previous embodiments, the variable intake control valve was controlled to be closed in the low and medium speed range and opened in the high speed range. The pulp opening degree may be continuously controlled depending on the engine speed and load.

In this way, by continuously controlling the opening degree of the valve, the movement of the torque characteristics becomes continuous, eliminating the feeling of stepped torque, and improving drivability.

For example, as shown in FIG. 12, the opening degree θ of the valve 18 is set to 0°, θ1. When θ2θs is changed to 90',
The torque characteristics change as shown in FIG.

Next, the embodiment shown in FIGS. 14 and 15 will be described.

In the previous embodiment, torque improvement was achieved by lengthening the effective intake pipe length in the low-medium speed range of the engine, but in the low-medium speed and low load operating range, if the effective intake pipe length was long, As the distribution between each cylinder worsens and the pumping loss increases, stability and partial fuel efficiency deteriorate. In order to improve such a problem, in this embodiment, the variable intake control pulp 18 is opened in an operating range where the load is relatively low even in the low-to-medium speed range, and control is executed to shorten the actual intake pipe length.

Therefore, the crank angle signal output from the crank angle sensor and the intake air flow rate signal output from the air flow meter are input to a control unit equipped with control means for the variable intake control valve 18, and the engine is controlled based on these output signals. The engine speed and the basic fuel injection amount are calculated, and the variable intake control valve 18 is controlled based on the engine speed and the basic fuel injection amount.

This control will be explained according to the flowchart in Fig. 14. In step (hereinafter abbreviated as S as in the figure) 1, the crank angle signal output from the crank angle sensor is read, and in S2, the engine speed N is calculated. do. S3
Then, the intake air flow rate signal output from the air flow meter is read, and in S4, the basic fuel injection amount T is calculated based on the engine speed NE and the intake air flow rate. In S5,
The engine speed N1 is compared with the set speed N, and N,
If ≧Nl (YES), it is determined that the high speed range is reached, and the process proceeds to S6, where control to open the variable intake control valve 18, for example, ON control of the step motor 20 is executed.

If N E < N + (NO), it is determined that the speed is in the low speed range and the process proceeds to S7. In S7, the basic fuel injection amount TP and the set injection amount TP + are compared, and if T≧TPI (YES), it is determined that the load is high, and the process proceeds to S8, where the variable intake control valve 18 is closed. In other words, the step motor 20 is turned off. TP < TP
If it is + (No), it is determined that the load is low, and the process proceeds to S6, where control to open the variable intake control valve 18 is executed.

Fig. 15 is a map showing the opening/closing range of the variable intake control valve 18 based on the above-mentioned control. is clear.

Therefore, in the low-medium speed and low-load operating range, distribution among the cylinders can be improved, reducing pumping loss and improving stability and partial fuel efficiency.

Next, the embodiment shown in FIGS. 16 to 18 will be described.

This example aims to further improve idle stability and torque at high output, and the intake manifold 12.13
In addition to the fuel injection valve 34 provided in the intake manifold 12.13, a fuel injection valve 35 is provided which injects fuel into the intake passage from the opening of the intake manifold 12.13 opened by the variable intake control valve 18.

That is, as shown in FIGS. 16 and 17, four fuel injection valves 35 are installed at predetermined intervals on the upper wall of the sub-collector 16.
Attach. The fuel injection valve 35 has a double nozzle type nozzle hole, and is configured to inject fuel toward the open ends of the two adjacent distribution pipes 17.

This fuel injection operation by the fuel injection valve 35 is performed when the variable intake control valve is opened during the day, and is performed during idling operation and high output operation.

Incidentally, when the engine is idling, fuel injection by the fuel injection valve 34 provided in advance in the intake manifold 12, 13 is not performed.

FIG. 18 shows the fuel injection area by the fuel injection valve 35 described above. The "closed" region in the figure is the closed region of the variable intake control valve 18, and the shaded region is the fuel injection region by the fuel injection valve 35.

It should be noted that during idling, no injection is performed by the fuel injection valve 34 provided in advance in the intake manifold 12,13.

By injecting the fuel upstream of the intake manifold 12, 13 in this manner, atomization of the fuel is promoted and stability at idle is improved.

Also, at high output, the intake manifold 12.13 is pre-filled.
Injection by only the fuel injection valve 34 provided for
This makes it possible to supplement the fuel that tends to be insufficient, making it possible to improve torque more effectively.

<Effects of the Invention> As explained above, according to the variable intake system for a V-type 8-cylinder engine of the present invention, the intake pipe length can be changed without increasing the size of the engine. By changing the pressure pulsation and changing the intake tuning speed, we have made it possible to drastically change the torque characteristics when the variable intake control valve opens and closes, so it is possible to change the torque characteristics in the low-medium speed range and high-speed range. It is possible to improve power performance by significantly improving both torque and power performance.

[Brief explanation of the drawing]

FIG. 1 is a front longitudinal cross-sectional view showing an embodiment of a variable intake system for a V-8 cylinder engine according to the present invention, FIG. 2 is a plan view of the same embodiment, and FIGS. 3 and 4 are respectively implementations of the same. FIG. 5 is a graph showing the torque characteristics in the above embodiment, and FIGS. 6 and 7 are graphs showing other embodiments of the variable intake system for the same type 8-cylinder engine as above. 8 is a sectional view of a hydraulic cylinder showing another embodiment of the pulp opening/closing means; FIG. 9 is a plan view showing another embodiment of the variable intake control valve; FIG. 10 11 is a front sectional view showing another embodiment of the variable intake control valve, FIG. 11 is a graph showing the torque characteristics according to the embodiment of FIG. 10, and FIG. 12 is a front sectional view showing another embodiment of the control structure. , FIG. 13 is a graph showing the torque characteristics according to the embodiment shown in FIG. 12, and FIGS. 14 and 15 are flowcharts showing other control structure embodiments, and the opening/closing range of the variable intake control valve based on this control. FIGS. 16 to 18 show further examples of other control structures. FIG. 16 is a cross-sectional view of the front joint of the engine, and FIGS. 17(a) and 17(b) are branch pipe sections. 18 is a graph showing the fuel injection area by the fuel injection valve in this embodiment, FIG. 19 is a front longitudinal sectional view showing an example of a conventional variable intake device, and FIGS.
Fig. 2 is a diagram showing the function of a variable intake system in a conventional six-cylinder engine, Fig. 20 is a schematic configuration diagram, Fig. 21 is a graph showing intake pressure pulsation characteristics, Fig. 22 is a graph showing torque characteristics, and Fig. 22 is a graph showing the intake pressure pulsation characteristics. Figures 23 to 26 are diagrams showing the functions of a variable intake system in a conventional 8-cylinder engine. Figure 23 is a schematic configuration diagram, Figure 24 is a graph showing intake pressure pulsation characteristics, and Figures 25 and 26. are graphs showing torque characteristics, respectively. 12.13... Intake manifold 16... Sub collector 17... Branch pipe 18... Variable intake control valve 18a... Valve body 19...
・Rotation axis 20...Step motor 21...
Control unit 26...hydraulic cylinder 2
9゜32... Valve body 29a, 32a... Opening 30... Actuator 31... Opening Patent applicant Nissan Motor Co., Ltd. Agent
Patent Attorney Fujio Sasashima Figure 3 Nawate-Kyushiki Suction 1 Valve 2 Crank Angle
-Fig. ! ! 1 time J - Fig. 26 Engine [ii'4A Follow □ Fig. 8 Fig. 9 Fig. 1 ○ Fig. 14 Fig. 15 - Cut & NE Fig. 16 Fig. 17 (a) (b) Fig. Figure 18: Transfer of closed fields - Figure 19-1:

Claims (1)

[Claims] A hollow collector is disposed between banks where intake manifolds provided corresponding to each of the eight cylinders intersect, and an opening provided in a part of each intake manifold is connected to the inner space of the collector. In addition, variable intake control valves that are opened and closed in conjunction with each other are provided in the openings, and a valve control means is provided that controls the opening and closing operations of the variable intake control valves according to engine operating conditions. Variable intake system for V8 engine.