JPS62191627A - Intake device for engine - Google Patents

Abstract

PURPOSE:To improve the reliability of an actuator operation in a change-over means for changing over the natural frequency of intake by constituting the actuator for driving the change-over means from a pressure operated system having as a drive source the supercharging pressure generated by the operation of a supercharger. CONSTITUTION:An intake path 11 communicating to an intake port 4 has a surge tank 12 and the intake path 11 at the upstream side of said tank 12 becomes a common intake path A. Also, the intake path 11 downstream of said tank 12 constitutes an independent intake path B of each cylinder from a branch pipe path 12b and an independent intake pipe 17. Said path B is connected to a subsurge tank 20 through a communicating path 19 having a switch valve 21 interposed as a change-over means. Then, the switch valve 21 is operated by a pressure operated system actuator 31, and an operating chamber 34 of the actuator 31 communicates so the intake path A between a throttle valve 16 and a compressor wheel 22a of a supercharger 22 through a piping 41, a three-way change-over valve 42 and a piping 43.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an intake system for an engine.

(Prior Art) Some engine intake devices are designed to increase engine torque as much as possible by improving volumetric efficiency by utilizing the inertia effect of intake percentage. In other words, the negative pressure IE force wave that occurs with the start of intake is reflected at the opening 11 end to the atmosphere or expansion chamber on the downstream side of the intake passage, and is turned into a positive pressure wave and returned toward the intake boat. However, by making this pressure wave reach the intake port on the verge of closing, the volumetric efficiency, that is, the torque, will be improved.

Such intake inertia effect is influenced by the natural frequency of the engine intake system.

This 1. The oscillating frequency itself has almost no dependence on the engine speed; Therefore, as is clear from the above explanation, the inertial effect of the intake air can only be expected at a certain engine speed that corresponds to the natural frequency of the engine intake system.
Normally, in order to improve low-speed torque, the natural frequency of the engine intake system is set so that the engine rotational speed at which this inertial effect should be obtained is relatively low.

For this reason, recently, a system has been proposed in which the natural frequency of the engine intake system is changed according to the engine speed, so that the inertial effect of the intake air can be obtained not only in the low speed range but also in the high speed range. There is.

That is, as shown in Japanese Unexamined Patent Publication No. 56-115819, an expansion chamber is connected to the intake passage, and an opening/closing block as a switching stage P is disposed between the intake passage and the expansion chamber. When the engine speed is low, by closing the opening/closing valve mentioned above, the length of the Kasada pipe in the engine intake system can be lengthened (while reducing the natural frequency and obtaining an inertial effect, By opening the L: open/close valve, the equivalent intake pipe length is increased by 1υ (increasing the natural frequency), and the inertial effect is also increased by 11). A valve in which the valve is driven by a negative pressure actuator has also been proposed (4 yen).
See Opening and Closing Publication No. 60-164619].

(Problems to be Solved by the Invention) 1- As mentioned above, when the switching for switching the fixed frequency of intake air is driven by a negative pressure actuator,
The negative pressure itself supplied to this actuator is
It is common to use what is generated in the intake passage. In this case, Jino's replacement! During i'J conversion operation,
Considering that negative pressure does not necessarily occur in the intake passage,
The negative pressure generated in the intake passage is stored in the -i, -1 negative pressure tank, and this negative pressure tank! , 7J as a negative pressure supply source for the exchange means.

However, when the switching means is driven using the intake negative pressure as described above, depending on the engine operation mode, the negative pressure in the negative pressure tank may be insufficient and the switching means is activated at a predetermined time. This could easily lead to a situation where they would no longer be able to do so. To explain this point in detail, for example, when accelerating from a start, you shift up sequentially to 1st, 2nd, and 3rd gears, and at the same time, you shift up to 4!2! In the event that an error occurs that causes the L stage to be activated, the y/o switching means is repeatedly activated each time the L gear is shifted up, while the negative pressure in the negative pressure tank is not replenished but is simply consumed. Twice [1 or 3 times] the operation of the switching F stage was not performed due to lack of negative pressure. Especially in vehicles such as AT cars, where the accelerator pedal is kept fully depressed even when changing gears (the throttle valve remains wide open).
Since almost no negative pressure is generated in the intake passage during start acceleration, no negative pressure is supplied to the negative pressure tank at all, and the above-mentioned negative pressure shortage phenomenon becomes even worse.
J! It turned out to be A.

It is conceivable to make the negative pressure tank considerably larger in order to solve the lack of negative pressure, but it is difficult to actually adopt this in consideration of the limited engine room space. In addition to this, the provision of a negative pressure tank itself becomes a problem in terms of the effectiveness of the engine room space (purposeful utilization -1), regardless of its size.

The present invention was made in consideration of the above-mentioned circumstances, and it is an object of the present invention to enable a pressure-operated actuator to operate continuously and reliably without separately providing a pressure storage section such as a negative pressure tank. One object of the present invention is to provide an intake system for an engine that can reliably switch the natural frequency of intake air at a predetermined time.

(Means and operations for solving the problem) In order to achieve the above-mentioned object, the present invention provides a point for generating supercharging pressure and a switching means for an engine equipped with a supercharger. When a point at which this supercharging pressure can be reliably generated at the switching timing is reached, the pressure-operated actuator is operated by this supercharging pressure. in particular.

In an engine intake system in which a switching stage R for switching the natural frequency of the intake air is switched and operated according to the operating state of the engine, the engine includes a supercharger that supercharges the intake air, and a supercharger that supercharges the intake air, and a supercharger that supercharges the intake air; A pressure-operated seven-stage switch is operated by the supercharging pressure generated by the
It consists of a cutter and a glaze.

With this configuration, supercharging is always performed in the high engine speed range where it is time to switch the switching means, especially in the high speed and high load range where large torque due to the inertia effect of the intake air is desired to ensure output. As a result, supercharging pressure for operating the actuator is secured above.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

In Fig. 1, l is a 4-cycle reciprocating type engine (generally a gasoline engine), and as is well known, this is a combustion chamber defined in the -L direction of a reciprocating piston 2. 3, an intake boat 4 and an exhaust port 5 are opened, and the intake boat 4 is opened to the engine 1 by the intake box 6, and the exhaust port 5 is opened by the exhaust boot t7.
It is designed to be opened and closed in synchronization with the output shaft (not shown). In the embodiment, the piston 2
It is said to be a multi-cylinder structure with multiple cylinders arranged perpendicular to the paper and sunken.

The intake passage 11 connected to the intake boat 4 has three surge tanks 12 defining an expansion chamber 12a therein.

The intake passage 11 on the downstream side of the L surge tank 12 is a common intake pipe 13 that constitutes one Jl: ventilation passage A, and the common intake pipe 13 includes, in order from the I', fat side, An air cleaner 14, an air flow meter 15, a compressor wheel 22a of an exhaust turbo supercharging fi 22, and a throttle valve 16 are provided. In addition, the main surge tank 1
2 and each intake boat 4 are connected by independent intake pipes 17, the number of which corresponds to the number of cylinders. That is,
The intake passage 11 of the main surge tank 12 is configured as an independent intake passage B for each cylinder by a branch pipe part 12b integrally formed with the main surge tank 12 and a gamma intake pipe 17. Intake passage B times! The lengths are approximately equal to each other. Then, each German 1″1.
A fuel injection valve 18 is disposed at the downstream end of the intake passage B.

On the other hand, in the exhaust passage 23 of the engine l, the supercharging a22
When the turbine wheel 22b is rotationally driven by the exhaust energy, the compressor wheel 22a is rotated via the shaft 22C, and supercharging is performed.

Each of the independent intake passages B is connected to a sub-surge tank 20 defining a sub-enlargement chamber 20a via a communication passage 19 on the upstream side of the fuel injection valve 18. This communication path 29
The length is short, from the combustion chamber 3 to the L surge tank 1.
2 (-IE expansion chamber 12a) is longer than the length from the combustion chamber 3 to the sub-surge tank 20 (sub-expansion chamber 20a). And in the communication path 19! , an on-off valve 21 as an IJ exchange means is provided,
This on-off valve 21 is opened and closed by a pressure-operated actuator 31, which will be described later.

Here, the equivalent intake pipe length determined by the independent intake passage B, that is, the length from the combustion chamber 3 to the main enlarged chamber 12a, is made long as described above, so that the natural frequency of the intake air is reduced. is set to . As a result, when the on-off valve 21 is fully closed (opening valve 9JO=0°), an inertial effect of intake air is produced at low engine speeds. The equivalent intake pipe length when the on-off valve 21 is fully open (opening/closing angle 0 = 70°) is the short length from the combustion chamber 3 to the sub-enlargement chamber 20a via the communication passage 19, and the intake pipe at this time The natural frequency of will be large. As a result, an inertial effect of intake air can be obtained in a high engine speed range.

The actuator 31 will be explained with reference to FIG.
is defined. This diaphragm 33 is connected to the rod 3
5, and in the embodiment, when the diaphragm 33 is displaced in the direction F in FIG.
is rotated in the opening direction, and the palm surface is
The return spring 36 is biased to the position shown in FIG. When supercharging pressure, which will be described later, is supplied to the working chamber 34, the tire flam 33 is displaced downward in FIG. 2, and the on-off valve 21 is fully opened.

The working chamber 34 of the actuator 31 is connected to a magnetic three-way switching valve 42 via a pipe 41. A pipe 43 is further connected to this three-way νJ switching valve 42, and the pipe 43 connects the throttle valve 16 and the combiner wheel 22.
It communicates with the inside of the intake passage A between the intake passage A and the air intake passage A. As a result, depending on the dino switching mode of the three-way switching valve 42, the piping 41 is
It is adapted to be selectively communicated with the piping 43 or the other end.

7JS1 In the figure, 51 is a control unit consisting of a microcomputer, and to this control unit 51, intake air signals t and y from the air flow meter 15 and an engine rotation speed signal from the rotation speed sensor 52 are input. Further, the control unit 51 outputs power to the fuel injection valve 18 and the three-way LJJ switching valve 42. Of course, the three-way switching valve 42 by this control unit 51
This control is performed when the engine speed is below a predetermined set speed (for example, set around 500 Orpm for an engine with a maximum allowable speed of 700 Orpm).
The piping 41 is communicated with the atmosphere (the on-off valve 21 is closed), and [
- When the rotation speed is higher than the set rotation speed, connect the piping 41 to tH? 43
and open/close valve 2 using supercharging pressure as described later.
1 is opened. In addition, fuel injection valve 1
The fuel injection j1 from 8 is determined based on the intake air, lit: and engine speed),
This point has been well known in the past and is not directly related to the present invention, so a detailed explanation thereof will be omitted.

Here it is! In a configuration like 2, for example, during starting acceleration, especially at least when driving at low speed, the engine speed is shifted up from the above-mentioned set rotation speed, which is the opening/closing νJ switching timing of the on-off valve 21. In some cases,
The on-off valve 21 is required to be operated repeatedly, such as closing, opening, closing, and opening φφ after shifting up. Such repeated opening and closing of the on-off valve 21 is performed by opening the working chamber 34 to the atmosphere in the actuator 31 and supplying supercharging pressure to the first working chamber 34 . That is, in a low engine speed range where the on-off valve 21 is kept closed, atmospheric air is supplied to the working chamber 34 by the switching mode of the three-way switching valve 42, and the on-off valve 21 is closed. On the other hand, when the engine rotates at high speeds, especially at high loads that require output, the three-way switching valve 42 is switched to connect the working chamber 34 to the piping 43 side, thereby reducing the overload caused by the operation of the supercharging@22. Supply pressure is supplied to the working chamber 34, and the on-off valve 21 is opened. In this way, in the operating range where switching of the on-off valve 21 is required, supercharging pressure is generated at [minutes]. tA replacement can be performed reliably.

Although eleven embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

(1) As an intake passage configuration for switching the natural frequency of intake air, for example, the German S'Z intake passage B (intake pipe 17) may be extended iA'd+:i, or its diameter may be changed to Of. etc., an appropriate structure may be adopted.

(?) When supercharging pressure is supplied to the working chamber 34, the switching “
The opening/closing brake r21 as a step may be closed.

(3) When the control unit 51 is configured by a computer, it may be either a digital type or an analog type.

(4) The supercharger 22 may be of a so-called supercharger type that is mechanically driven by an engine output shaft.

(Effects of the Invention) As is clear from what has been described below, the present invention can reliably switch at a predetermined time by continuously repeating the 12 stages of switching for switching the natural frequency of intake air.

Also, the pressure is like a negative pressure tank! Since a separate storage section is not required, it is advantageous in making use of a wide space in the engine room.

[Brief explanation of drawings]

FIG. 1 is a system reading diagram showing an embodiment of the present invention. FIG. 2 is a sectional view showing an example of a pressure-operated actuator. A: Common intake passage B: Independent intake passage 1: Engine 11: Intake passage 12:) Surge tank 12a: Main expansion chamber 16: Throttle valve 19: Communication passage 20: Sub-surge tank 20a: Sub-expansion chamber 21: Open/close valve (Switching means) 22: Supercharger 31: Pressure-operated 7-cut unit 34: Working chamber 41: Piping 42: Three-way switching valve 43: Piping (for supercharging pressure supply) 51: Control unit 52: Engine rotation speed sensor

Claims (1)

[Claims] (1) In an engine intake system in which a switching means for switching the natural frequency of the intake air is switched and operated according to the operating state of the engine, the engine includes a supercharger that supercharges the intake air, and an operation of the supercharger. An intake system for an engine, comprising: a pressure-operated actuator for driving the switching means, the actuator being operated by boost pressure generated in conjunction with the switching means.