JPH05223040A - Intake device for engine - Google Patents

Abstract

PURPOSE:To attain combustion stability by matching the time of the air flow in an intake port and the time of fuel injection from an injector to the utmost regardless of the engine speed at the time of high rotation or low rotation, and injecting the fuel in response to the intake speed in the intake port. CONSTITUTION:An auxiliary intake port 4 is branched from a main intake port 3 at a position near an engine combustion chamber 13 on the downstream side of an intake passage 7, the intake passage cross sectional area of the auxiliary intake port 4 is set sufficiently smaller than that of the main intake port 3, a main injector 1 and the first opening/closing valve 5 at the upstream of the main injector 1 are arranged on the main intake port 3, and an auxiliary injector 2 having an injecting capability for the unit time smaller than that of the main injector 1 is arranged on the auxiliary intake port 4. The main injector 1, auxiliary injector 2, and first opening/closing valve 5 are properly controlled by a control means in response to the engine load state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine intake device.

[0002]

2. Description of the Related Art Conventionally, in order to improve fuel efficiency, exhaust gas and output of an engine, it is effective to promote vaporization and atomization of fuel and to generate swirl and tumble flow of a strong air-fuel mixture in an engine combustion chamber. Is said. Therefore, as disclosed in JP-A-60-75719, the main intake port and the auxiliary intake port are branched near the engine combustion chamber on the downstream side of the intake passage so that the swirl flow is mainly generated from the auxiliary intake port. There is known a configuration for supplying injection fuel from an injector to the.

On the other hand, in order to perform stable combustion in the engine combustion chamber from high rotation speed to low rotation speed, regardless of the engine speed (load), the air-fuel mixture is supplied as homogeneously as possible and the combustion is performed. It is necessary to generate swirl and tumble flows with strong air-fuel mixture in the room. Therefore, conventionally, a relatively large capacity injector, which is determined from the maximum rating of the engine, is provided for each cylinder,
At high load and high speed, the air-fuel mixture is supplied by injecting fuel into the intake port, which has a relatively high flow velocity at a predetermined timing according to the engine speed, while at low load and low speed. In the same manner, in the same manner, the injector is controlled to inject fuel into the intake port in a low flow velocity state that is slower than during high rotation at a predetermined timing according to the engine speed.

As described above, the fuel injection is controlled to stably generate the swirl flow in the engine combustion chamber, especially at low rotation speed, to stabilize the combustion. On the other hand, in order to obtain a homogeneous air-fuel mixture, it is effective to match the time when intake air (introduced air) flows in the intake port with the time when fuel is injected from the injector as much as possible. It is known that in order to generate in the engine combustion chamber, it is necessary to give directionality to a homogeneous mixture and promote atomization at a high flow rate.

[0005]

However, as described above, by using a common injector having a relatively large capacity determined from the maximum rating and the like, the engine can be operated under high load high speed and low load low speed. If fuel is injected into the intake port at a predetermined timing according to the number of revolutions, the injector has a large capacity as described above, especially at low revolutions such as when the load is low. The injection will end.

As a result, it becomes impossible to match the time during which intake air (introduced air) flows in the intake port with the time during which fuel is injected from the injector. Also, since the flow velocity inside the intake port is considerably lower than that at high load and high speed, atomization cannot be promoted even if fuel is injected into the intake port, so combustion stability at low speed deteriorates. However, there is a problem that it adversely affects fuel economy and exhaust.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is irrespective of whether the engine speed is high or low.
Combustion stability is aimed at by making the time to flow in the intake port and the time to inject fuel from the injector match as much as possible and injecting fuel according to the intake speed in the intake port.

[0008]

[Means for Solving the Problems] and

In order to solve the above-mentioned problems and achieve the object, the present invention supplies the fuel injected by the injector by branching into a main intake port and an auxiliary intake port near the engine combustion chamber on the downstream side of the intake passage. In the intake device of the engine, the intake flow passage cross-sectional area of the auxiliary intake port is set to be sufficiently smaller than that of the main intake port, and the main injector has a main injector and a first opening / closing valve upstream of the main injector. An auxiliary injector having a smaller injection capacity per unit time than the main injector is installed in the auxiliary intake port, and the main injector, the auxiliary injector, and the opening / closing valve are appropriately controlled according to the engine load state. And a first opening / closing valve upstream of the main injector to open at least the main injector when the engine load is large. From well as fuel injection through the main intake port, when the engine load is small, the auxiliary injector so as to fuel injection via the auxiliary intake port serves to ensure combustion stability.

Further, fuel is supplied from the auxiliary injector until the fuel injection timing from the auxiliary injector approaches a predetermined timing with respect to the closing timing of the intake valve, and when the fuel injection timing exceeds the predetermined timing, the fuel is also supplied from the main injector in addition to the auxiliary injector. Controlled by the control means to supply fuel,
It works to ensure combustion stability. Further, by introducing exhaust gas recirculation upstream of the auxiliary intake port and injecting fuel from the auxiliary injector via the auxiliary intake port when the engine load is small, combustion stability is ensured and exhaust purification is performed. To work. Then, a second opening / closing valve is arranged upstream of the auxiliary intake port to inject fuel in accordance with the engine load to ensure combustion stability.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional plan view of an essential part of the engine according to the first embodiment, and FIG. 2 is a cross-sectional view taken along the line XX of FIG. First, in FIG. 1, the intake portion is configured such that a throttle valve 11 shown by a broken line is arranged in a main intake passage 10 connected to an air cleaner from the upstream side, and a branch portion 9 has seven branch intake passages 7 The air-fuel mixture can be supplied into the combustion chamber 13 of the engine via the first intake valve 12a, and the exhaust gas after combustion is exhausted to the exhaust gas 14 via the exhaust valve 18, It collects and exhausts. Here, the configuration described above is a normal 4
The structure is substantially the same as that of a 4-cylinder 4-cylinder engine. In the case of an engine such as a 6-cylinder 2-valve engine or a 3-cylinder 4-valve engine, the number of branch intake passages 7 and valves, and the number of exhaust pipes 14 are appropriately changed. The redundant description will be omitted, and the 4-cylinder 4-valve engine shown will be described as a representative.

Again in FIG. 1, the branch intake flow passage 7 is branched into a main intake port 3 and an auxiliary intake port 4 near the engine combustion chamber 13 on the downstream side, and the main injector 1 is installed in the main intake port 3. Further, the auxiliary intake port 4 is provided with the auxiliary injector 2 having a smaller injection performance per unit time than the main injector 1. Next, each port sets the intake flow passage cross-sectional area of the auxiliary intake port 4 to be sufficiently smaller than that of the main intake port 3, and the auxiliary intake port 4 introduces outside air from the branch intake flow passage 7 through the inlet portion 4b. However, the air-fuel mixture is supplied to the second intake valve 12b via the outlet portion 4a. As shown in the drawing, the outlet portion 4a is bent as shown in the drawing in order to allow the air-fuel mixture to be supplied along the inner peripheral surface of the combustion chamber 13, so that a swirl flow can be generated.

On the other hand, a first opening / closing valve 5 is arranged upstream of the main injector 1 so as to be interlocked with the main injector 1 as shown in the drawing, and the control to be described later is carried out together with the main injector 1 and the auxiliary injector 2 in accordance with the rotation state of the engine. I'm trying to do it. Next, in the sectional view taken in the direction of the arrow in FIG. 2, a valve opening / closing device 32 connected to the main control device 23 is connected to the throttle valve 11 and the first opening / closing valve 5 of the intake portion. On the other hand, a fuel supply device 20 for supplying fuel is connected to the main injector 1 and the auxiliary injector 2 as shown in broken lines, while a main controller 23 is connected via a driver device 21 for opening and closing each injector. It is connected.

Further, in this figure, the auxiliary intake port 4
As shown in the figure, the outlet portion 4a of the fuel cell 2 can generate a tumble flow in the combustion chamber 13 by supplying the air-fuel mixture obliquely above the second intake valve 12b, and together with the swirl flow described above, Combustion can be promoted within 13. That is, since the auxiliary intake port 4 is set to have a sufficiently smaller intake passage cross-sectional area than the main intake port 3, when performing the intake from the auxiliary intake port 4 when the main intake port 3 is closed. Because the flow velocity increases,
The swirl and tumble flows are surely generated in the combustion chamber 13 to promote combustion.

Also, the cross-sectional area of the intake flow passage of the main intake port 3 is smaller than that of the conventional one by at least providing the auxiliary intake port 4, so that the flow velocity in the main intake port 3 can be increased as compared with the conventional one. it can. First in the configuration described above
An example of the control will be described based on the first operation diagram of FIG. 3. After starting the engine in step S1, step S2 is performed.
Then, it is determined whether or not the engine load is large, and if YES, the process proceeds to step S3. Also, NO
In case of, it progresses to step S5. In step S3, the main controller 23 controls and drives the first on-off valve 5 to open,
Before or after this, the fuel is injected from the main injector 1 in step S4.

On the other hand, if it is determined in step S2 that the engine load is small and the engine speed is small, step S2 is performed.
5, the main controller 23 controls and drives the first on-off valve 5 so as to close it, and before and after this, the injection time of the auxiliary injector 2 is set to be long in step S6, and step S6 is performed.
At 7, the fuel is injected from the auxiliary injector 2. By repeating the above operation, the time during which intake air (introduced air) flows through the auxiliary intake port 4 and the time during which fuel is injected from the auxiliary injector 2 are made to coincide with each other, thereby promoting the mixture of the air-fuel mixture. Further, since the main intake port is closed in the auxiliary intake port 4, the flow velocity is high even if the engine is in the low speed rotation state. Therefore, fuel injection into the auxiliary intake port 4 can promote atomization. As a result, the combustion stability at low rotation speed is greatly improved in combination with the above-mentioned cooperation with the swirl and tumble flows.

Next, FIG. 4 shows the second configuration in the above description.
6 is an operation diagram of a control example of FIG. In this figure, step S1
At 0, reading of various operating states is executed by the main controller 23 after the engine is started. The fuel injection amount is calculated in step S11 based on the read result.
Next, in the case where the load is small and the fuel can be supplied only by the auxiliary injector, the fuel injection end timing in the engine crank rotation is calculated in step S12, and the process proceeds to step S13. This step S1
In 3, it is judged whether the fuel injection end timing approaches the predetermined timing or more with respect to the intake valve closing timing. Then, the process proceeds to step S15, and fuel is injected from the auxiliary injector 2. On the other hand, when it is determined that the fuel injection end timing approaches the predetermined timing or more with respect to the intake valve closing timing, the process proceeds to step S16, and the first opening / closing valve is opened. After that, the process proceeds to step S17, in which fuel is injected from both the main injector 1 and the auxiliary injector 2, and only the injection amount that could not be injected by the auxiliary injector 2 is injected by the main injector 1.

Here, the auxiliary injector 2 may perform a plurality of fuel injections such as twice and three times during the injection time. By repeating the above operation, in addition to the effect of the operation of FIG. 3, atomization is promoted by injecting fuel into the auxiliary intake port 4 even if the engine is in the minimum low speed rotation state such as the idling state. As a result, the combustion stability at low speed is improved, and fuel consumption and exhaust emissions are not adversely affected. Furthermore, when the engine is in the maximum rotation state, fuel can be injected from both the auxiliary intake port 4 and the main intake port 3 having a high flow rate, so atomization can be promoted.

Next, FIG. 5 is a sectional plan view of an essential part of an engine according to the second embodiment, and FIG. 6 is a sectional view taken along the line YY of FIG. In both figures, common components already described in FIG. 1 and FIG. 2 are denoted by the same reference numerals and the description thereof is omitted, and the description is limited to different parts (additional components). The portion 16 is provided with an inlet portion 30 for taking in exhaust gas recirculation (EGR). The inlet portion 30 guides the exhaust gas to the EGR valve portion 28 via the exhaust gas recirculation passage 29. The operating valve 27 controls the opening / closing of the EGR valve portion 28 according to the intake pressure.
It is operated by the intake pressure from the EGR main outlet portion 31 which is open with respect to, and is configured to pass the exhaust gas when the intake pressure is low. An EGR distribution pipe 25 is connected to the EGR valve portion 28, and exhaust gas recirculation (EGR) is performed via the EGR outlets 26 provided in the auxiliary intake ports 4 described above.

In the above structure, in addition to the effect described with reference to FIG. 3, exhaust gas recirculation (EGR) is performed in the auxiliary intake port 4 even if the engine is in the low speed rotation state, and the fuel injection is performed as described above. As a result, atomization can be promoted, and as a result, combustion stability at low speeds can be improved and the limit can be extended. Further, FIG. 7 is a cross-sectional plan view of the main parts of the engine according to the third embodiment. In this figure, the common components already described with reference to FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted. Only the difference will be described. An opening 40a is opened in the portion so that the introduced air can be introduced into the auxiliary intake port 40. The auxiliary injector 2 is attached to the auxiliary intake port 40.
Is provided, so that the air-fuel mixture can be supplied through the outlet 40a of the auxiliary intake port 40 branched to each cylinder as shown in the figure.

With the above structure, only one auxiliary injector 2 needs to be provided, so that the cost can be reduced when the auxiliary intake port 40 can be branched at low cost. The opening / closing operation of the first opening / closing valve 5 is also performed in substantially the same manner as described above. Next, FIG. 8 is a cross-sectional plan view of an essential part of the engine according to the fourth embodiment, showing only one cylinder. In this figure, common components already described in FIG. 1 and FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. The inside is divided into a main intake port 3 and an auxiliary intake port 4. In other words, each intake port is provided directly from the branch portion 9 to the combustion chamber 13, and the first opening / closing valve 5 is provided in the main intake port 3 while the main injector 1 and the auxiliary injector 2 are provided side by side. I have to. Further, the exhaust gas recirculation (E
An outlet 26 for GR) is provided.

According to the above construction, the auxiliary intake port can be formed more easily, and the injectors 1 and 2 can be provided in parallel. The first on-off valve described above may be specially controlled to increase the flow velocity. FIG. 10A is a correlation diagram of the opening degree of the throttle valve and the accelerator depression amount, which is applied to each of the above-described embodiments. In this figure, the opening of the throttle valve rises in proportion to the accelerator depression amount taken along the horizontal axis to obtain a throttle valve opening straight line A. The above-mentioned first opening / closing valve is the illustrated first opening / closing valve. As indicated by curve B, control is performed so that the throttle valve opening is opened when the throttle valve opening is increased. By controlling in this way, the combustion stability at low speed is improved and the limit is extended.

Next, FIG. 9 is a cross-sectional plan view of an essential part of the engine according to the fifth embodiment, and FIG. 10 (b) is a correlation diagram of the opening degree of the throttle valve and the accelerator depression amount in the same embodiment. Is. In FIG. 9, common components already described with reference to FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof will be omitted.
A second opening / closing valve 6 for opening / closing the auxiliary port 4 is further arranged between the auxiliary injector 2 and the EGR outlet 26.

With the above structure, the exhaust gas is guided to the auxiliary port 4 through the exhaust gas recirculation passage 29, and at the same time, as shown in FIG.
As shown in (b), the second on-off valve is operated like a control curve C to improve combustion stability at low rotation speed. It is needless to say that the above-mentioned respective embodiments can be appropriately set and changed without departing from the essence of the invention. For example, the present invention is not limited to the combustion chamber of one cylinder and four valves, and the conventional combustion chamber of one cylinder and two valves. I do not care.

[0024]

As described above, according to the present invention, the time for flowing through the intake port and the time for injecting fuel from the injector match as much as possible regardless of the engine speed at high speed and low speed. Combustion stability can be achieved by injecting fuel in accordance with the intake speed in the intake port.

[Brief description of drawings]

FIG. 1 is a cross-sectional plan view of essential parts of an engine according to a first embodiment.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a first operation explanatory diagram of the first embodiment.

FIG. 4 is a second operation explanatory diagram of the first embodiment.

FIG. 5 is a cross-sectional plan view of the main parts of the engine of the second embodiment.

6 is a cross-sectional view taken along the line YY of FIG.

FIG. 7 is a cross-sectional plan view of essential parts of an engine of a third embodiment.

FIG. 8 is a cross-sectional plan view of an essential part of an engine according to a fourth embodiment.

FIG. 9 is a cross-sectional plan view of an essential part of an engine according to a fifth embodiment.

10A and 10B are correlation diagrams of the opening degree of the throttle valve and the accelerator depression amount.

[Explanation of symbols]

 1 main injector, 2 auxiliary injector, 3 main intake port, 4 auxiliary intake port, 5 1st opening / closing valve, 6 2nd opening / closing valve, 13 combustion chamber, 23 main control device, 26 EGR outlet.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location F02D 41/34 F 9039-3G F02M 69/00 (72) Inventor Yoshinori Hayashi Fuchu-cho, Aki-gun, Hiroshima Prefecture Shinchi No. 3 Mazda Co., Ltd.

Claims (4)

[Claims] 1. An intake system for an engine, which supplies fuel injected by an injector by branching into a main intake port and an auxiliary intake port near an engine combustion chamber on a downstream side of an intake passage, wherein the auxiliary is provided more than the main intake port. The intake passage cross-sectional area of the intake port is set to be sufficiently small, the main intake port is provided with a main injector, and a first opening / closing valve is provided upstream of the main injector, and the auxiliary intake port has a unit larger than that of the main injector. An intake device for an engine, comprising: an auxiliary injector having a small injection capacity per unit time; and a control means for controlling the main injector, the auxiliary injector, and the on-off valve according to an engine load state. 2. The engine intake system according to claim 1, wherein fuel is supplied from the auxiliary injector until the fuel injection timing from the auxiliary injector approaches a predetermined timing with respect to the closing timing of the intake valve, and the fuel injection timing exceeds the predetermined timing. In this case, the engine intake device is controlled by the control means so that fuel is supplied from the main injector in addition to the auxiliary injector. 3. The intake system for an engine according to claim 1, further comprising introducing exhaust gas recirculation upstream of the auxiliary intake port. 4. The intake system for an engine according to claim 1, wherein a second opening / closing valve is arranged upstream of the auxiliary intake port.