JPH0326832A - Intake system structure of engine - Google Patents

Abstract

PURPOSE:To improve a transient characteristic by arranging a first throttle valve near the downstream side of a fuel supply device, and a second throttle valve which is closed in an interlocked manner at the vicinity of an intake manifold collection part on the downstream side. CONSTITUTION:In an intake flow passage 14 which reaches a collection part 5a of an intake manifold 5, an air cleaner 1, an injector 2, a main throttle valve 10, a supercharger 3 and an auxiliary throttle valve 4 are arranged from the upstream side, in order, and mixed air is supplied to an engine body 6. In this case, since an injector 2 is arranged at a position apart from the manifold collection part 5a, distribution to respective cylinders is improved with uniformly mixed fuel. The fuel is injected toward a main throttle valve 10 so that atomization is facilitated so as to improve acceleration transient characteristics. Since respective throttle valve 10, 4 are closed in an interlocked manner, adhered fuel at an intake manifold 5 side is decreased, and less adhered fuel is sucked even in the case of negative pressure at the time of deceleration, thereby overrich conditions can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of an engine intake system suitable for use in automobiles.

[Conventional Technology] In general, in the intake system of a multi-cylinder engine installed in a vehicle such as an automobile engine, a throttle valve is provided in the intake passage leading to the intake manifold gathering part, for example, single point injection (hereinafter referred to as SPI). Fuel supply devices such as engine and carburetors are usually installed upstream of the throttle valve. In particular, the fuel supply device is provided at an upstream portion near the throttle valve, and can promote atomization of the fuel by jetting the fuel toward the throttle valve.

In such a conventional engine intake system structure, for example, when a supercharger is installed in the intake system,
A fuel supply device such as an SPI or a carburetor and a throttle valve are arranged upstream of the supercharger.

[Problems to be Solved by the Invention] However, if the fuel supply device and throttle valve are placed upstream of the supercharger as in the conventional engine intake system structure described above, the air flow from the fuel supply device and throttle valve to the combustion chamber will be reduced. The volume of the injected fuel becomes larger, and the amount of injected fuel attached to the inner wall of the intake passage increases. Therefore, the amount of injected fuel attached to the inner wall of the intake passage on the T: flow side of the throttle valve is also large, and when the vehicle decelerates, the amount of injected fuel attached to the inner wall of the intake passage increases. When the downstream side of the throttle valve becomes negative pressure, the adhering fuel in this area is sucked into the combustion chamber, causing over-richness in the combustion chamber, which causes misfires and the like, deteriorating the deceleration transient characteristics.

Note that FIGS. 4(a) to 4(e) are graphs showing various characteristics (time changes) during such deceleration, and FIG. 4(a) shows the supercharger output pressure (S/C
OUTP). Figure 4(b) shows the air-fuel ratio (A/F).
Figure 4(c) shows the output torque (TORQUE), Figure 4(c) shows the output torque (TORQUE),
d) is the Karman vortex generation frequency (KARMAN) as an intake flow rate parameter, Figure 4(e) is the throttle opening (TPS), and the unmeasurable area in Figure 4(b) is ) is the area where the fuel is extremely overrich and cannot be measured. The intake flow rate (flow rate) and supercharger output pressure (intake pressure) decrease, leading to an overrich air-fuel ratio and a large deceleration shock (sudden decrease in torque).

Additionally, even if a supercharger is not installed, increasing the distance between the fuel supply device and the combustion chamber, for example to improve the distribution of fuel to each cylinder or due to layout constraints, will reduce the fuel supply. The volume from the device to the combustion chamber becomes large, and the above-mentioned problems are likely to occur.

The present invention was devised in view of such problems, and
It is an object of the present invention to provide an intake system structure for an engine that allows good deceleration transient characteristics even in an intake system with a large volume from a fuel supply device to a combustion chamber.

[Means for Solving the Problems] Therefore, in the intake system structure of the engine of the present invention, in the intake system of a multi-cylinder engine, the upstream portion of the intake passage leading to the gathering portion of the intake manifold is separated from the gathering portion. A fuel supply device is disposed at the position, a first throttle valve is disposed downstream of the fuel supply device and close to the fuel supply device, and a first throttle valve is disposed at the downstream portion of the intake passage. The present invention is characterized in that a second throttle valve that can be closed in conjunction with the closing of the first throttle valve is disposed at a close position or within the gathering portion.

[Function] In the above-described engine intake system structure of the present invention, the fuel supply device is disposed at a position away from the gathering portion of the upstream portion of the intake passage leading to the gathering portion of the intake manifold.
While the fuel flows through the intake passage, it is mixed uniformly and the distribution of fuel to each cylinder is improved.

Further, since the first throttle valve is disposed downstream of the fuel supply device and close to the fuel supply device,
By injecting fuel from the Vi fuel supply device toward the first throttle valve, atomization of the fuel is promoted,
Acceleration transient characteristics are improved, and fuel is less likely to adhere to the inner wall of the intake passage.

On the other hand, since the volume from the fuel supply device to the combustion chamber increases, the total amount of injected fuel adhering to the inner wall of the intake passage increases. Since a second throttle valve is provided that can be closed in conjunction with the closing of the first throttle valve, there is little fuel adhering downstream of the second throttle valve. Even if the downstream side of the second throttle valve becomes negative pressure during deceleration, only this small amount of adhering fuel will be sucked into the combustion chamber, and over-richness in the combustion chamber will be prevented.

[Examples] Examples of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing the structure of an engine intake system as a tth embodiment of the present invention, and FIGS. 2 and 3 show the structure of an engine intake system as a second embodiment of the present invention. Fig. 2 is a schematic diagram of its structure, and Fig. 3 is a flowchart showing its operation. The intake system structure of each embodiment is installed in a multi-cylinder engine installed in a vehicle such as an automobile engine, and is equipped with a supercharger.

First, the first embodiment will be explained. As shown in FIG.
In the intake flow path l4 leading to a, from the upstream side, an air cleaner l, a single point injection (SPI) 2 as a fuel supply device, a first throttle valve (main throttle valve) 10, a supercharger 3, and a second
Throttle valves (auxiliary throttle valves) 4 are arranged in order.

In other words, the SPI2 is a 9 main throttle valve 1 provided at a position upstream of the supercharger 3 in the intake passage l4 and away from the intake manifold gathering part 5a.
0 is provided on the downstream side of the SPI 2 in the intake passage 14 and close to the SPI 2. In particular, the SPI 2 has its fuel injection direction directed toward the main throttle valve 10.

Further, the auxiliary throttle valve 4 is provided in the intake passage 14 at a position downstream of the supercharger 3 and close to the intake manifold gathering portion 5a. The auxiliary throttle valve 4, together with the main throttle valve 10, is linked to the accelerator pedal by a mechanical interlocking mechanism using a normal throttle mechanism or an electric interlocking mechanism using throttle-by-wire, so that the opening degree can be changed! 11m!
It is supposed to be done.

Note that 6 is the engine body, 7 is the exhaust manifold, and 8 is the engine body.
9 is a bypass passage provided in parallel with the supercharger 3, and 9 is a bypass valve that is opened when the supercharger 3 is stopped.

The engine intake system structure according to the first embodiment of the present invention is as follows:
Since the configuration is as described above, when fuel is injected from the SPI 2 toward the main throttle valve 10, this fuel is mixed with the air supplied through the air cleaner 1 and atomized, and the fuel is ejected from the SPI 2 toward the main throttle valve 10. It is atomized by This also reduces fuel adhesion to the inner wall of the intake passage 14.

Subsequently, the supercharger 3 that performs supercharging within the intake passage 14 agitates the intake air in conjunction with the supercharging to further promote atomization of the fuel, so that the air flow from the SPI 2 to the intake manifold gathering portion 5a is In the intake passage 14, the fuel is sufficiently atomized and evenly distributed to each intake manifold 5 of the engine 6.

Therefore, there is an effect that the acceleration transient characteristics during acceleration of the vehicle are improved.

In addition, since the SPI 2 is provided upstream and the supercharger 3 is provided in the middle of the intake passage 14, the volume from the SPI 2 to the combustion chamber of the engine body 6 becomes large, and the injected fuel flows to the inner wall of the intake passage 14. However, since the auxiliary throttle valve 4 is located close to the intake manifold gathering part 5a, the auxiliary throttle valve 4 is closed during deceleration, and the downstream side thereof becomes negative pressure. Also, those affected by this negative pressure are:
Only a small amount of fuel adheres to the downstream side of the auxiliary throttle valve 4, and only this small amount of fuel is sucked into the combustion chamber. Therefore, over-richness in the combustion chamber is prevented, and the transient deceleration characteristics of the vehicle when the vehicle is decelerated are improved.

Next, the second embodiment will be described. As shown in FIG. An air cleaner 1, a single point injection (SPI) 2 as a fuel supply device, a first throttle valve (main throttle valve) 10, a supercharger 3, and a second throttle valve (auxiliary throttle valve) 4 are arranged in this order. However, in the first embodiment, the auxiliary throttle valve 4 is linked to the raw throttle valve 10, whereas in the second embodiment, the auxiliary throttle valve 4 is independent from the main throttle valve 10. It is designed to move. In other words, the main throttle valve 10 is linked to the accelerator pedal by a mechanical interlocking mechanism using a normal throttle strategy or an electric interlocking mechanism using throttle-by-wire, and the degree thereof is adjusted. Then, the auxiliary valve [1 valve 4 is the main valve 4] - When the valve 10 is open, it is always kept fully open (see the dotted line in Figure 2), and is fully closed when the vehicle decelerates.

For this reason, in order to detect the deceleration state of the vehicle, the main slot position sensor which detects the opening degree of the main throttle valve 10]. 1, a valve opening/closing device 2 for opening and closing the auxiliary throttle valve 4, and a controller 15 for controlling the operation of the valve opening/closing device 12 based on detection signals from the slot position sensors 1, 1. There is.

In addition, in the controller 1-0-, the controller 15 can determine that the vehicle is decelerating when the main throttle valve 10 is closed, for example, based on the detection signal from the throttle position sensor 1l, and the valve opening/closing device 12 On the other hand, in other cases, that is, when the vehicle is not decelerating, a valve closing signal is output to the valve opening/closing device 12.

In addition, the valve opening/closing device 12 may include, for example, an auxiliary slot I-
The return spring that always biases the throttle valve 4 to the fully open state, and the controller 1 to l: actuated in response to the valve closing signal from the I-ra 15. It consists of a full RJIJM motive force that moves open to a closed state.

This fully-closed acclimatization mechanism operates when a valve closing signal is received from the controller 15, and power is supplied to control the auxiliary throttle valve 4 against the turn spring until it is fully closed.・When the hull close release request is received from the roller 15, the power supply is stopped and the power to the fully closed side is turned off.
It is conceivable to use a solenoid or a motor to remove the noise.

As the second embodiment of the present invention, the structure of the intake system of the engine with τ is as follows:
With the above-described structure, the auxiliary throttle valve 4 is opened and closed as shown in flowchart 1-1 of FIG.

'In other words, when the throttle position 0 value of the main throttle valve 10 is detected by the throttle position sensor 11- (step a1), the controller
5, this detection signal c=. Based on W, it is determined whether the vehicle is decelerating (step a2).

This judgment is based on the rate of increase d of the value of the throttle position θ.
This is performed based on whether O/d t is less than or equal to a set value N (N<O). This is because when decelerating, the accelerator pedal is normally released, so the throttle health is more than a certain level.
Since it is closed at a speed of 2, d O/d
When t: is smaller than a predetermined negative value N, the deceleration state ε is determined.

If the vehicle is decelerating, a valve close ('R signal is output at the valve opening/closing position 12) so as to close the auxiliary throttle valve 4 (step a3). In response, the valve opening/closing device 12 is fully opened. The drive mechanism operates and the auxiliary throttle valve 4 is fully closed.

On the other hand, when the vehicle is not decelerating, the auxiliary throttle valve 4 is opened. A valve closing release signal is output to the valve opening/closing device 12 (step a4). In response to this, the closing movement of the valve opening/closing device @ 12 by the full closing mechanism is released, and the auxiliary throttle valve 4 is fully opened by the return spring.

In this way, as in the first embodiment, the atomization of the upstream fuel is promoted in the main slot regulator 10 and the supercharger 3, and the fuel is evenly distributed to the intake manifold 5 of each cylinder of the engine 6. , which has the effect of improving acceleration transient characteristics. In addition, when the speed is slow, the intake manifold collecting part 5
Auxiliary throttle valve 4 arranged at a position close to a
Closure of tb suppresses fuel intake into the combustion chamber during deceleration tb, prevents over-richness of the fuel t chamber, and improves deceleration transient characteristics.

In this embodiment, since the auxiliary throttle valve 4 is fully opened during deceleration, the increase in intake resistance due to the presence of the auxiliary throttle valve 4 is suppressed, which has the effect of preventing a reduction in engine output. .

In this embodiment, the valve opening/closing device 12 is actuated in response to a return spring that urges the auxiliary throttle valve 4 to a fully closed state and a valve closing release signal from the controller 15, and is operated to assist against the return spring. The throttle valve 4 may be configured with a full-open movement mechanism (for example, one using a solenoid or a motor) that can move the throttle valve 4 to a fully open state.

Furthermore, a stepper motor may be used as the valve opening/closing device 12. In this case, the stepper motor
Depending on the control signal from the controller 15, the auxiliary throttle valve 4 is driven fully open or fully open. Therefore, the return spring can be omitted.

In addition, in each embodiment, a single point injection (SPI) 2 is provided as a fuel supply device, but
The fuel supply device may be a carburetor.

Further, the auxiliary throttle valve 4 may be provided at an inlet portion within the gathering portion 5a.

Furthermore, the intake system of each embodiment includes a supercharger 3.
However, even if a supercharger is not installed, the fuel supply system (for example, SP
If the distance from I) to the combustion chamber is set long, the auxiliary throttle valve 4 may be moved to the intake manifold assembly portion 5a.
By providing it at a position close to , the transient characteristics are improved in the same way as described above.

[Effects of the Invention] As detailed above, according to the engine intake system structure of the present invention, in the intake system of a multi-cylinder engine, the air flow from the upstream portion of the intake passage leading to the gathering portion of the intake manifold. A fuel stand (feeding device) is installed at a separate location, and
A first throttle valve is disposed on the downstream side of the fuel supply device and close to the fuel supply device, and the first throttle valve is disposed at a position close to the gathering portion in the downstream portion of the intake passage or in the gathering portion. Due to the configuration in which a second throttle valve is provided that can be closed in conjunction with the closing of the throttle valve, acceleration and It becomes possible to improve the deceleration transient characteristics, and especially when the intake system is equipped with a supercharger, the effect of improving the acceleration and deceleration transient characteristics is remarkable.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing the structure of an engine intake system as a first embodiment of the present invention, and FIGS. 2 and 3 show the structure of an engine intake system as a second embodiment of the present invention. Figure 2 is a schematic diagram of its configuration, Figure 3 is a flowchart showing its operation, and Figures 4 (.) to (e) are graphs showing problems with the conventional intake system structure. Yes 5
Figure 4 (a) is a graph of supercharger output pressure characteristics, Figure 4 (b) is a graph of air-fuel ratio characteristics, Figure 4 (C) is a graph of output torque characteristics, and Figure 4 (d) is a graph of intake flow velocity. The characteristic graph, FIG. 4 (8), is a graph of the throttle opening characteristic. 1.1 air cleaner, 2..1 single point injection as fuel supply device (spB, 3...
Supercharger, 4--second throttle valve (auxiliary throttle valve), 5--intake manifold,
5a-Intake manifold gathering part, 6-Engine main body,
7.1 exhaust manifold, 8.-bypass J, 1.9-.
Bypass valve, 10--1st throttle valve (main throttle valve), 1l--throttle position sensor. 12--valve opening/closing device, 14-intake flow path, 15-controller.

Claims (1)

[Claims] In the intake system of a multi-cylinder engine, a fuel supply device is disposed in an upstream portion of an intake passage leading to a gathering portion of an intake manifold at a position away from the gathering portion, and a fuel supply device is provided downstream of the fuel supply device. A first throttle valve is disposed close to the supply device, and is located in a downstream portion of the intake passage close to the gathering portion or within the gathering portion, and is interlocked with the first throttle valve when the first throttle valve is closed. characterized in that a second throttle valve is disposed that can be closed by
Engine intake system structure.