JPS60184925A - Intake device for engine - Google Patents

Abstract

PURPOSE:To enhance the output power of an engine equipped with an intake pipe length control means, by providing a fluctuation factor detection means for detecting a sound speed fluctuation factor, and by performing the compensatory control of the length of an intake pipe depending on the output signal of the fluctuation factor detection means, to heighten the efficiency of inertial supercharging. CONSTITUTION:In a four-cylinder engine 1, an intake passage 3 is provided in such a manner that the upstream ends of branch intake pipes 5 connected to cylinders 2 are coupled to a common surge tank 6, and a throttle valve 8 is furnished in an intake pipe 7 at an introducing portion upstream to the surge tank. An expansible and compressible pipe 11 provided with a rack 11a is fitted movably back and forth in the intake pipe 7 to constitute an intake pipe length control means 10. The upstream end of the expansible and compressible pipe 11 is opened into an air cleaner 9. A pulse motor 12 for rotating a gear 12b engaged with the rack 11a is regulated by a control unit 13 to control the length of the intake pipe depending on the output of a rotational frequency sensor 17. The length of the intake pipe is controlled in a compensatory manner depending on the output of a sound speed fluctuation factor detection means 16 consisting of an intake air temperature sensor 14 and an atmospheric pressure sensor 15.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for an engine, and particularly to an intake system for an engine in which the length of the intake pipe is changed to improve output.

(Prior art) In general, engines take in air intermittently, so
Air column vibration occurs in the intake air, and this air column vibration affects the amount of intake air, that is, the engine output. This air column vibration is determined by intake system parameters such as intake pipe length, diameter, and collection volume.

In an engine with the above intake system specifications constant, the air column vibration is set to be optimal under the specified operating conditions, and the air column vibration is It works to my advantage, but in the immortal realm it actually works against me.

Therefore, for example, as seen in Utility Model Application No. 57-22629, a surge tank is provided as a metal part in the middle of the intake passage, and the intake pipe on the downstream side of this surge tank is made to have an expandable structure so that it can be adjusted according to the engine speed. Techniques have been proposed to improve output performance by changing the length and improving filling efficiency through inertia effects.

Therefore, the above-mentioned proposed technology has a so-called inertial supercharging effect in which the air column in the intake pipe is accelerated by the negative pressure generated in the cylinder at the beginning of the intake stroke, and the intake air is forced into the cylinder by the reverse pressure wave generated at the open end. This is what is being used. In addition, considering the surge tank and the intake system upstream of the surge tank by making the length of the intake pipe on the upstream side of the surge tank variable, we considered the intake pressure waves of each cylinder as the vibration source, and compared the vibration source and the above intake system. There is also a technique that utilizes the so-called resonance effect, in which a response delay occurs between the air column vibration and the filling efficiency increases when the air column vibration period and the excitation source period (engine rotation speed) match.

However, in any case, the natural frequency of the air column of the intake system is a function of the length of the air column as well as the speed of sound. Therefore, for example, when the temperature or atmospheric pressure changes, the speed of sound changes, which causes the natural frequency of the air column to change, and the length of the intake pipe, which is synchronized with the engine speed, also changes. In the case where the intake pipe length is changed accordingly, there is a problem that the intake pipe length cannot always be controlled to be the optimum length to obtain the maximum inertial effect or resonance effect, and the effect in the exit direction is insufficient.

(Object of the Invention) In view of the above circumstances, the present invention provides an engine intake system that maximizes the resonance or inertial supercharging effect even when factors that change the speed of sound such as temperature and atmospheric pressure change. The purpose is to provide the following.

(Structure of the Invention) An intake system for an engine according to the present invention is provided with an intake pipe length control means for controlling the length of the intake pipe according to the engine speed, and a variable element detection means for detecting an element in which the speed of sound varies. and a correction means for correcting and controlling the intake pipe length by operating the intake pipe length control means based on the signal from the variable element detection means.

<Effects of the Invention> According to the present invention, the period of air column vibration in the intake system is synchronized with the period of intake air of the engine based on the fluctuation of sound speed fluctuation factors such as temperature and atmospheric pressure detected by the fluctuation element detection means. By changing the length of the intake pipe, it is possible to obtain the optimum tuning conditions even when the fluctuation factors of sound speed change, and to maximize the resonance or inertial supercharging effect to achieve the desired result. It is possible to plan the direction of output.

<Example> Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings.

Embodiment 1 FIG. 1 schematically shows the overall configuration. Each cylinder 2 of a four-cylinder engine 1 is connected to an intake passage 3 for supplying intake air and an exhaust passage 4 for discharging combustion gas. Above intake passage 3
The upstream sides of the branch intake pipes 5 connected to each cylinder 2 are connected to a common surge tank 6, and a throttle valve 8 is interposed in the intake pipe 7 at the introduction part upstream of the surge tank 6. At the same time, the intake pipe 7 of the introduction section is connected to an air cleaner 9 provided with a cleaner element 9a.

Further, the intake pipe 7 upstream of the surge tank 6 is provided with an intake pipe length control means 10 that changes the intake pipe length in accordance with the engine speed. The intake pipe length control means 10 includes a telescoping pipe 11 disposed within the intake pipe 7 so as to be movable forward and backward.The upstream end of the telescoping pipe 11 opens into the air cleaner 9, and from this open end the intake pipe 7 connects to the surge tank. The length of the intake pipe up to the part where it connects to 6 can be changed.

The movement of the telescopic tube 11 is carried out by the operation of the pulse motor 12 by meshing a gear 12b fixed to the drive shaft 12a of the pulse motor 12 with a rack lla formed in the telescopic tube 11. A control signal from the control unit 13 is outputted to control its operation, and the length of the intake pipe is adjusted and controlled.

Further, the surge tank 6 is provided with an intake air temperature sensor 14 that detects the intake air temperature, and an atmospheric pressure sensor 15 that detects the atmospheric pressure, and both sensors 14 and 15 detect variations in the speed of sound. Variable element detection means 16
is configured.

The control unit 13 receives the signals from the variable element detection means 16, that is, the detection signals from the intake air temperature sensor 14 and the atmospheric pressure sensor 15, and the engine speed signal from the engine speed sensor 17, and processes them in response to the engine speed. This basically controls the length of the intake pipe, and also corrects and controls the length of the intake pipe in response to variations in the speed of sound. Furthermore, the above-mentioned controller) to roll unit 13 are connected to the pulse motor 1.
It receives the intake pipe length signal from 2 and performs feedback control of the intake pipe length.

The control unit 13 receives the signal from the engine speed sensor 17, calculates the basic intake pipe length corresponding to the engine speed, and adjusts the telescopic pipe 11 to a predetermined value based on the difference between the signal and the intake pipe length signal from the pulse motor 12. a basic control circuit 18 that outputs a basic control signal for moving to a position;
An arithmetic circuit 19 receives the signals from the intake air temperature sensor 14 and the atmospheric pressure sensor 15 and calculates a correction coefficient corresponding to the sound velocity fluctuation; A correction circuit 20 for correcting the signal is provided.

The operations of the fan 1 to the roll unit 13 will be explained based on the flowchart shown in FIG. After starting, in step S1, the engine speed N is read based on the signal from the engine speed sensor 17, and it is determined whether this engine speed N is within the control range (adjustable range corresponding to the change range of the intake pipe length). Only when this determination is YES and within the control range does the process move to the next step S3 to perform intake pipe length control.

In step S3, the basic intake pipe length Lo corresponding to the engine speed N is calculated, and then the intake air temperature T and atmospheric pressure P are read from the intake air temperature sensor 14 and the atmospheric pressure sensor 15, respectively (S4), and in step S5, the intake air temperature T It is determined whether the temperature is within the allowable range α with respect to the reference temperature To, that is, whether temperature correction is necessary, and if it exceeds the allowable range α (No), the basic intake pipe length is Perform Lo temperature correction. After this temperature correction, the STETSU
At step S7, it is determined whether atmospheric pressure ph < reference pressure Pa is within the allowable range β, that is, whether atmospheric pressure correction is necessary. In step S8, the basic intake pipe length is determined. Perform atmospheric pressure correction. The above-mentioned temperature correction and atmospheric pressure correction are based on the characteristics shown in FIG. 3, and a correction coefficient a corresponding to the intake air temperature T and atmospheric pressure P is used.

When the intake air temperature is high or the atmospheric pressure P is low, the intake pipe length Lo is corrected to become longer.

The current intake pipe length 1 is read against the value of the basic intake pipe length Lo corrected above (S9), and the difference L between the two is read in step S10.
It is determined whether the absolute value of Lo is less than or equal to the allowable value γ, and if it exceeds the allowable value γ (No>, the amount of movement of the telescopic tube 11 is preset from the value of the difference L Lo in step 811. After calculating and setting based on the map and outputting a drive signal to the pulse motor 12 based on the map (512) and changing the intake pipe length, the process returns to step S1.

Therefore, according to the above embodiment, by moving the telescopic pipe 11 of the intake pipe length control means 10, the length of the intake pipe upstream of the surge tank 6 is basically made longer when the engine speed is low and shortened when the engine speed is high. In addition to this, the length of the intake pipe is corrected and controlled in response to variations in the speed of sound, thereby maximizing the resonance supercharging effect and aiming for an upward exit direction.

Embodiment 2 This embodiment relates to an intake system designed to obtain an inertial supercharging effect. FIG. 4 shows the overall configuration, and in the one shown in FIG. While an intake pipe length control means 10 for changing the pipe length is installed, in this example, the length of the branched intake pipe 5 downstream of the surge tank 6 is changed.

That is, each branch intake pipe 5.5 connected to each cylinder 2
..., the telescopic tubes 23, 23, whose upstream ends open into the surge tank 6, are each arranged inwardly so as to be movable forward and backward.
The movement of the telescopic tubes 23, 23, . . . is controlled by a pulse motor 24,
Gears 24b, 24b... fixed to the drive shaft 24a of
The intake pipe length control means 25 is configured to mesh with each other so that all cylinders are operated simultaneously by the operation of the pulse motor 24.
is installed, and the pulse motor 27I is operated by a control signal from the control unit 26 to adjust and control the intake pipe length.

The control unit 26 includes the intake air temperature sensor 14 of the variable element detection means 16 and the atmospheric pressure sensor 1 as in the previous example.
5 and engine rotational speed sensor] 7, and controls the intake pipe length in accordance with the engine rotational speed, while also performing temperature correction and atmospheric pressure correction to compensate for changes in the speed of sound. .

The rest is provided in the same manner as in the previous example, and the same structures as those in FIG.

In this embodiment as well, the length of the intake pipe downstream of the surge tank 6 is changed by moving the telescopic pipe 23 of the intake pipe length control means 25.
Basically, the length of the intake pipe is controlled to be long when the engine speed is low, and shortened when the engine speed is high.In addition, the length of the intake pipe is corrected in response to fluctuations in the speed of sound, which results in inertial supercharging. I'm trying to get the most out of it and get the most out of it.

(d-) As the mechanism for changing the length of the intake pipe upstream or downstream of the surge tank, a well-known structure for changing the length of the intake pipe that utilizes a telescopic pipe as in the above embodiment can be adopted.

[Brief explanation of drawings]

Fig. 1 is a general schematic diagram of an engine equipped with an intake system according to a first embodiment of the present invention, Fig. 2 is a flowchart showing the operation of the control unit shown in Fig. 1, and Fig. 3 is an intake air temperature. Or a characteristic diagram showing the relationship between atmospheric pressure and the supplementary f coefficient of the intake pipe length. FIG. 4 is an overall schematic configuration diagram of an engine equipped with an intake device according to a second embodiment of the present invention. 1...Engine 3...Intake passage 5.
...Branch intake pipe 6 ...Surge tank 7
...Intake pipe 10.25...Intake pipe length control means 11.23.
...Extensible tube 12.24...Pulse motor 13.26...Control unit 14...
... Intake temperature sensor 15 ... Atmospheric pressure range - 16 ... Fluctuation element detection means 17 ... Engine rotation speed sensor No. 1 Fig. 4 Fig. 3 Fig.

Claims (1)

[Claims] (1) In an engine equipped with an intake pipe length control means that controls the length of the intake pipe according to the engine speed, a variable element detection means detects an element that changes the speed of sound, and a signal from this variable element detection means is used. An intake system for an engine, comprising: correction means for correcting and controlling the intake pipe length by activating the intake pipe length control means.