JPH0355789Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) This invention relates to an intake system for an internal combustion engine that includes a plurality of intake valves and intake passages.

(Prior Art) Various technologies have been proposed to variably control the intake air flow (swirl) in the combustion chamber depending on the operating condition, with the aim of improving the fuel efficiency of internal combustion engines (Japanese Patent Application Laid-Open No. 1983-1999).
(Refer to Publication No. 105534, etc.)

7 and 8 show that the intake passage downstream of the intake manifold 1 is divided into an auxiliary intake passage 2 and two main intake passages 3 and 4. The auxiliary intake passage 2 is connected to the combustion chamber 7 via the intake valve 6, and the auxiliary intake passage 2 merges with one of the main intake passages 3 immediately before the intake valve 5. A shutoff valve 8, which closes when the engine is running at low speed and under low load, is installed in the main intake passages 3 and 4.
9 is interposed.

At low speed and low load when the shutoff valves 8 and 9 are closed, intake air flows only from the auxiliary intake passage 2, which biases the intake air flow and increases the flow velocity, creating a strong swirl within the combustion chamber 7. Therefore, the combustion speed is increased and thermal efficiency is increased, so engine performance such as fuel efficiency is improved.

In addition, at high speed and high load when the shutoff valves 8 and 9 open,
Since the intake air flows through each of the passages 2, 3, and 4, there is no resistance to the intake air, and therefore, the intake air filling efficiency is increased and the initial engine output is ensured. Furthermore, 1
0 and 11 indicate exhaust valves.

By the way, in one of the main intake passages 3 and 4, when the isolation valve 9 is closed, combustion gas blows back from the combustion chamber 7 through the intake valve 6, causing the isolation valve 9 to close.
Carbon and the like tend to adhere to the shutoff valve 9, making it easy to get dirty.

Therefore, in this example, to prevent that blowback,
An air passage 12 is formed that opens downstream of the cutoff valve 9, and air is directly supplied from upstream of a throttle valve (not shown) to the main intake passage 4 downstream of the cutoff valve 9.

In addition, 13 and 14 are electromagnetic valves and their control circuits that open and close the air passage 12, and the electromagnetic valve 13 is connected to the cutoff valves 8 and 9.
When the air passage 12 is closed, the air passage 12 is opened.

(Problem that the invention attempts to solve) However, in such conventional examples,
Since the diameter of the air passage 12 is constant, the following problem occurs.

For example, if the diameter of the air passage 12 is large, it will be effective in preventing contamination of the shutoff valve 9, but under operating conditions such as when the engine is idling, where the amount of intake air is extremely small, the amount of air from the air passage 12 will be large. Therefore, the amount of intake air flowing in from the sub-intake passage 2 decreases accordingly.
For this reason, it becomes impossible to obtain a good swirl in the combustion chamber 7.

On the other hand, if the diameter of the air passage 12 is small, under operating conditions where the amount of intake air is large, the amount of air from the air passage 12 will be insufficient even though the amount of gas blown back from the combustion chamber 7 will increase. Therefore, it is difficult to prevent the shutoff valve 9 from becoming dirty. If the dirt becomes particularly severe, the shutoff valve 9 may malfunction or become stuck.

The purpose of this invention is to prevent the isolation valve from becoming contaminated while ensuring a predetermined swirl depending on the operating state.

(Means for solving the problem) As shown in Fig. 1, this invention consists of a commonly used auxiliary intake passage D connected to the combustion chamber A via intake valves B and C, and a main intake passage for high output. In an internal combustion engine, the main intake passage E is provided with a shutoff valve F that opens and closes depending on the load, and means G, H, and I for detecting the operating state of the engine, and downstream of the shutoff valve F are provided. A bypass air passage J that opens on the side and supplies air to the main intake passage E, and a bypass air amount control means K that controls the amount of air supplied are provided, and a bypass air passage J that is open to the side and supplies air to the main intake passage E, and a bypass air amount control means K that controls the amount of air supplied, Based on this, the supply air amount is increased as the intake air amount increases when the shutoff valve F is closed.

(Function) Therefore, when the shutoff valve F is closed, the amount of air supplied from the bypass air passage J to the downstream side of the shutoff valve F increases, so that the shutoff valve is closed due to the blowback of combustion gas from the combustion chamber A. Contamination of F is accurately prevented, and on the other hand, in extremely low speed and low load conditions, the amount of air from the bypass air passage J is reduced to maintain good swirl formation by the intake air flowing in from the auxiliary intake passage D.

(Example) Figures 2 and 3 are a schematic configuration diagram showing an example of the present invention and its a-a sectional view, where 7 is a combustion chamber, 5, 6
3 and 4 are intake valves, 3 and 4 are main intake passages that are divided downstream of the intake manifold 1, and 2 is a sub-intake passage that is also divided and joins one of the main intake passages 3 immediately before the intake valve 5.

Reference numerals 8 and 9 indicate shutoff valves that are driven by actuators (not shown) and close the main intake passages 3 and 4 when the engine is running at low speed and low load.

However, in this example, two main intake passages 3, 4 and cutoff valves 8, 9 are provided per cylinder, but the main intake passage 3 and cutoff valve 8 where the auxiliary intake passage 2 joins are not provided, as shown in FIG. You can also do it like this.

A bypass air passage 15 opens downstream of the cutoff valve 9 and supplies air directly from upstream of a throttle valve (not shown) to the main intake passage 4 downstream of the cutoff valve 9.
is formed.

This bypass air passage 15 is divided into a first passage 16 and a second passage 17 in the middle, and an orifice 18 is provided in the first passage 16, and an orifice 19 and a solenoid valve 20 are provided in the second passage 17. equipped.

On the other hand, as means for detecting the operating state of the engine, there are provided a vehicle speed sensor 21 that detects the vehicle speed, a rotation sensor 22 that detects the engine rotational speed, and an intake air amount sensor 23 that detects the engine intake air amount.

The detection signals from each of these sensors 21 to 23 are
The signals are input to a control circuit 24 serving as bypass air amount control means, and the control circuit 24 controls opening and closing of the solenoid valve 20 based on these detection signals.

For example, the control circuit 24 closes the solenoid valve 20 when the vehicle speed, rotational speed, or intake amount is lower than a predetermined value, and opens the solenoid valve 20 when the vehicle speed, rotational speed, or intake amount is lower than a predetermined value.

Next, the operation will be explained based on the flowchart of FIG.

In S1, the vehicle speed V, rotational speed N, and intake air amount Q are read, and in S2, the engine fuel supply amount T is calculated from the rotational speed N, intake air amount Q, and constant k.

Then, in S3 to S5, the vehicle speed V, the rotation speed N, and the fuel supply amount T are each compared with predetermined values, and if any one of these is smaller than the predetermined value, that is, in the extremely low speed and low load range of the engine, the process proceeds to S6. Solenoid valve 20
is closed.

Therefore, at this time, the air that has passed only through the first passage 16 from the bypass air passage 15 is supplied to the main intake passage 4 on the downstream side of the cutoff valve 9, but since the amount of air is small, the air that has passed only through the first passage 16 is supplied from the auxiliary intake passage 2. This no longer affects the amount of intake air flowing into the combustion chamber 7.

This prevents combustion gas from blowing back from the combustion chamber 7 to the shutoff valve 9 side when the engine is operating at very low speeds and under low load, including idling, while ensuring that the air flowing in from the sub-intake passage 2 maintains a good flow in the combustion chamber 7. Swirl can be ensured.

On the other hand, when vehicle speed V, rotational speed N, and fuel supply amount T are all greater than predetermined values in S3 to S5,
The solenoid valve 20 is opened in S7.

Then, air that has passed through the first passage 16 and the second passage 17 is supplied from the bypass air passage 15 to the main intake passage 4 on the downstream side of the shutoff valve 9, and the amount of air is increased. Ru.

Therefore, under such operating conditions, the combustion chamber 7
Although the amount of combustion gas blown back from the engine increases, this blowback can be accurately prevented by the air from the bypass air passage 15, and thereby the isolation valve 9 can be reliably prevented from becoming contaminated.

Note that in this operating state, the intake air amount of the engine increases to a certain extent, so even if the amount of air from the bypass air passage 15 is increased, a predetermined swirl can be maintained in the combustion chamber 7.

By the way, as shown in FIG. 5, the opening/closing conditions for the solenoid valve 20 are as follows: vehicle speed V, rotational speed N, and fuel supply amount T.
The solenoid valve 20 may be closed only when both of the values are smaller than a predetermined value. In this case, even in an extremely low speed range, if the load is high to some extent, the amount of air from the bypass air passage 15 is increased, making it more effective to prevent contamination of the shutoff valve 9. Also, of course, the solenoid valve 20
It is also possible to control the opening and closing of the engine using one of the following parameters: vehicle speed, rotational speed, and intake air amount.

In addition, as shown in FIG. 6, the bypass air passage 1
The diameters of the orifices 18 and 19 interposed in the first and second passages 16 and 17 may be set to different sizes. However, 25 is a three-way solenoid valve that selectively switches between the passages 16 and 17 in response to a signal from the control circuit 24.

(Effects of the invention) As described above, according to the invention, the amount of air supplied from the bypass air passage to the main intake passage downstream of the shutoff valve is increased or decreased depending on the operating condition, so that the amount of air flowing from the auxiliary intake passage This has the effect of accurately preventing fouling of the shutoff valve due to blowback of combustion gas while ensuring good flow of intake air in the combustion chamber.

[Brief explanation of the drawing]

Fig. 1 is a diagram corresponding to claims, Figs. 2 and 3 are schematic configuration diagrams showing an embodiment of the present invention and a sectional view taken along line a-a, and Figs. 4 and 5 are flowcharts showing the control contents. , FIG. 6 is a schematic block diagram showing another embodiment of the present invention, and FIGS. 7 and 8 are a schematic block diagram of a conventional example and its sectional view taken along the line bb. 2... Sub-intake passage, 3, 4... Main intake passage,
5, 6... Intake valve, 7... Combustion chamber, 8, 9... Shutoff valve, 15... Bypass air passage, 16... First
passage, 17... second passage, 20... solenoid valve,
21... Vehicle speed sensor, 22... Rotation sensor, 23
...Intake air amount sensor, 24...Control circuit.

Claims (1)

[Scope of utility model registration request] Detects the operating state of the engine in an internal combustion engine in which a combustion chamber is provided with a sub-intake passage and a main intake passage, each connected to the combustion chamber via an intake valve, and the main intake passage is equipped with a cutoff valve that opens and closes depending on the load. means, a bypass air passage that opens downstream of the shutoff valve and supplies air to the main intake passage, and a bypass air amount control means that controls the amount of air supplied, and detects a signal from the operating state detection means. An intake device for an internal combustion engine based on the above, wherein the amount of supplied air is increased as the amount of intake air increases when the shutoff valve is closed.