JPH03100322A - Intake control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To suppress a rapid change in a flow speed so as to reduce intake noise by controlling intake energy in such a manner that amplitude of the directly detected intake flow speed can stay below a certain fixed value. CONSTITUTION:A physical quantity detecting means 5, constituted of a full pressure pickup and a static pressure pickup, is mounted to an intake pipe 3. Here in a control unit 20, an intake flow speed and its amplitude are calculated being based on an output of the physical quantity detecting means 5 in accordance with a program stored in a memory in the inside. A control value for controlling the intake flow speed is calculated so that the amplitude obtains a predetermined value, and a control signal is output to a step motor 14. Thus, by driving a variable valve 13 by the step motor 14 being based on the control signal, an inlet passage to a branch chamber 12 is controlled to open and close with intake energy controlled. Accordingly, intake noise can be reduced by suppressing a rapid change of the intake flow speed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake control device for an internal combustion engine.
The present invention relates to a device that controls intake by directly detecting intake flow velocity.

(Prior art) Generally, in internal combustion engines such as four-stroke engines,
The volumetric efficiency, which is the ratio between the volume of the air-fuel mixture drawn into the combustion chamber and the stroke volume of the internal combustion engine, greatly affects the output characteristics of the engine. It is known that this is affected by the configuration of the intake and exhaust systems and the engine speed.

For this purpose, devices for controlling intake air have been developed, and a conventional intake control device for this type of internal combustion engine includes, for example, an exhaust pipe length variable device described in Japanese Patent Application Laid-Open No. 62-45928. This device detects the pressure inside the combustion chamber with a pressure sensor and controls the exhaust pipe length based on the detection result, making it possible to predict the volumetric efficiency of the internal combustion engine and improve variable control of the exhaust pipe length. The aim is to improve accuracy and increase intake efficiency as a result.

(Problem to be Solved by the Invention) However, in such a conventional intake control device for an internal combustion engine, the pressure inside the cylinder is detected by a pressure sensor,
The exhaust pipe length is controlled based on the detection results, but the pressure inside the cylinder varies greatly depending on the combustion state, non-king, etc.
Since it is difficult to accurately predict the volumetric efficiency, it is necessary to reduce the intake noise caused by the large amplitude of the flow velocity, especially when the intake flow velocity changes suddenly (for example, during engine deceleration). The problem was that it couldn't be done.

(Object of the Invention) Therefore, the present invention provides an intake @ control device for an internal combustion engine that can directly detect the intake air flow velocity, keep the amplitude of the intake air flow velocity within a certain value based on this information, and reduce intake noise. is intended to provide.

(Means for Solving the Problems) In order to achieve the above object, the intake control device for an internal combustion engine according to the present invention detects a physical quantity related to the flow velocity of intake air, as the basic conceptual diagram is shown in FIG. means a, a flow velocity calculation means for calculating the intake air flow velocity based on the output of the physical quantity detection means a; an amplitude calculation means C for calculating the amplitude of the intake air flow velocity; It includes a control means d that calculates a control value for controlling the intake air flow rate, and an intake energy operation means e that operates the intake energy based on the output of the control means d.

(Function) In the present invention, the intake flow rate is directly detected, and the intake energy is controlled so that the amplitude of the intake flow rate is within a certain value.

Therefore, rapid changes in flow velocity are suppressed and intake noise is reduced.

(Example) Hereinafter, the present invention will be explained based on the drawings.

2 to 6 are diagrams showing an embodiment of an intake air control device for an internal combustion engine according to the present invention. First, the configuration will be explained. In FIG. 2, reference numeral 1 denotes an in-line four-cylinder engine, in which intake air is supplied to each cylinder through an air cleaner 2 and an intake pipe 3, and fuel is injected by an injector (path shown).

The mixture in the cylinder explodes due to the discharge action of the spark plug.
It is burned, becomes exhaust gas, and is discharged from the exhaust manifold 4.

Physical quantity related to the flow rate of air taken into engine 1 (
In this embodiment, the static pressure and total pressure of intake air are detected by the physical quantity detection means 5.

Here, as shown in FIG. 3, the physical quantity detection means 5 is composed of a total pressure pickup 10 and a static pressure pickup II attached to the intake pipe 3.

These are for measuring the flow velocity of intake air in the intake pipe 3 by applying the principle of a so-called Pitot tube. Specifically, as shown in FIG.
, lla are provided, and the static pressure P1 and total pressure (total pressure) pz of intake air are measured by the piezoelectric elements 10a and 10a, respectively, and converted into electrical signals and taken out to the outside.

On the other hand, on the downstream side of the physical quantity detection means 5 in the intake pipe 3, a branch chamber 12 is provided branching from the intake pipe 3, and a variable valve 13 is arranged in the inlet passage of the branch chamber 12. The variable valve 13 controls the communication area of the branch chamber 12 with respect to the intake pipe 3, and is driven by a step motor 14. The step motor 14 drives the variable valve 13 based on a control signal Sc from a control unit 20, which will be described later. do. The branch chamber 12, variable valve 13, and step motor 14 constitute an intake energy operating means 15 for operating intake energy.

The output signal of the physical quantity detection means 5 is input to the bypass filter 1G, and only a predetermined high frequency component is controlled.
It is sent to the knit 20. The control unit 20 has functions as a flow velocity calculation means, an amplitude calculation means, and a control means, and is mainly composed of a microcomputer.
Calculates the intake air flow velocity and its amplitude according to a program stored in internal memory, calculates a control value for controlling the intake air flow velocity so that the amplitude is a predetermined value, and outputs a control signal Sc to the step motor 14 do.

Next, the effect will be explained.

FIG. 5 is a flowchart showing an intake amplitude control program, and this program is executed once every predetermined time. First, in step Sl, the intake air flow velocity U is calculated as follows.

Read the static pressure P1 in the intake pipe 3 from the output of the static pressure pickup 11, read the total pressure P2 from the output of the total pressure pink amplifier 10, and calculate the dynamic pressure from the difference between the total pressure P2 and static pressure P according to the following formula. Find, ρu” = Pz
-PH However, ρ: Calculated as the density of exhaust gas. Note that the above equation is based on Bernoulli's theorem, and it is well known that velocity can be calculated from pressure.

Next, in step S2, the rate of change U of the flow velocity U is determined.

This can be done by finding the amount of change in U per unit time, and is calculated using the formula, for example, 0 = U - U, where U is the value before a predetermined unit time. In step S, it is determined whether the flow velocity change rate u7 is positive or negative, and when u7≧O, it is determined that the flow velocity U is increasing, and in step S4, the maximum value of the flow velocity U is
8 and proceeds to step S6. When u7<0, it is determined that the flow velocity U is decreasing, and in step S, the minimum value of the flow velocity U is set as uL, and the process proceeds to step S6. In step S6, the amplitude ΔU of the flow velocity U is calculated from the formula Δu=uI4-uL, and in step S7 this is compared with a predetermined value (control determination value) K. When Δu<K, it is determined that the amplitude is small and the intake noise is tolerable, and in step S, processing is performed to set A=O (A: previous amplitude value) and F=0 (F: control flag). Return to S1. Note that at the start of the program, the process of A-0°F=O is performed as an initial setting. When ΔU≧, it is determined that noise suppression is necessary, and in step S9, it is determined whether ΔU≧A holds true. This is to determine whether the amplitude is larger than the previous amplitude. When it is true, the control flag F is determined in step 3+11 in order to determine the direction of flow velocity control, and when F=1, step SI+'? :
Set F=0, and when F=O, set F=1 in step S1□
The process then proceeds to step S13. On the other hand, if this is not true, the process jumps to step SI3. Step S13
Then, determine the control flag F, and if F=1, proceed to step 3.
At step 14, the variable valve 13 is driven in the direction of closing by a predetermined opening degree. Moreover, when F=0, step SI5
The variable valve 13 is driven in the direction of opening by a predetermined opening degree.

Thereafter, in step SI6, ΔU is set to A and the routine ends.

As a result, the branch chamber 12 communicates with the intake pipe 3 through a passage area determined by the opening degree of the variable valve 13, and the resonance frequency of the entire intake pipe 3 changes.

In addition, the resonant frequency is, however, a: sound speed r: cross-sectional area of the pipe ■ Nijilinda volume! = pipe length, and the cylinder volume (2) approximately increases due to the communication of the branch chamber 12, and the resonance frequency changes. When this resonant frequency changes, the position of the sparse/dense intake air in the intake pipe 3 changes, and the flow velocity substantially changes. Therefore, the intake flow velocity changes under the influence of the resonance frequency, and in the case of this embodiment, feedbank control is performed such that the amplitude of the flow velocity is always within a predetermined value, as shown in FIG. The amplitude that is the source of noise is finely and sufficiently suppressed. Comparing this control with the conventional example, we can see that while the conventional example predicts the volumetric efficiency indirectly using the in-cylinder pressure, this example detects the intake flow rate, a parameter directly related to noise, and controls the intake air. This means that intake noise can be reduced as the intake amplitude is reduced.

Note that the configuration of the intake energy operating means 15 is not limited to the above embodiment; for example, it may open and close a bypass passage,
Alternatively, the passage area of the intake pipe 3 may be directly reduced. At that time, the pipe diameter is determined so that the intake resistance does not increase.

Further, although a pitot tube is used as the physical quantity detection means 5 in the above embodiment, the present invention is not limited to this, and a resonator or other means may be used.

(Effects) According to the present invention, since the flow velocity of intake air is directly detected and the amplitude of the flow velocity is kept below a predetermined value, it is possible to suppress rapid changes in flow velocity and reduce intake noise.

[Brief explanation of drawings]

FIG. 1 is a basic conceptual diagram of the present invention, and FIGS. 2 to 6 are diagrams showing an embodiment of an intake air control device for an internal combustion engine according to the present invention.
FIG. 2 is a diagram showing the overall configuration, FIG. 3 is a diagram showing the arrangement of the physical quantity detecting means, FIG. 4 is a diagram showing the configuration of the physical quantity detecting means, and FIG. 5 is a flowchart showing the intake amplitude control program. , FIG. 6 is a diagram illustrating its operation. l...Engine, 3...Intake pipe, 5...Physical quantity detection means, 10...Total pressure pickup, 11...Static pressure Pick-up, 12... Branch chamber, 13... Variable valve, 14... Step motor, 15... Intake energy operating means, 16...
...Bypass filter, 20...Control 1-roll unit (flow rate XHt
i means, amplitude calculation means, control means).

Claims (1)

[Scope of Claims] a) physical quantity detection means for detecting a physical quantity related to the flow velocity of intake air; b) flow velocity calculation means for calculating the flow velocity of intake air based on the output of the physical quantity detection means; c) amplitude of the intake air flow velocity. d) a control means that calculates a control value for controlling the intake flow rate so that the amplitude of the intake flow rate is equal to or less than a predetermined value; and e) control means that operates the intake energy based on the output of the control means. An intake control device for an internal combustion engine, comprising: an intake energy operating means;