JPH0612062B2 - Intake system for multi-intake valve engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to an intake device for a multi-intake valve type engine mainly used in automobiles.

[Conventional technology]

Generally when trying to increase the maximum output of the engine,
The pipe length of the intake pipe must be set to match the maximum output speed. However, with this setting, it becomes difficult to obtain a large torque in other speed ranges of the engine, particularly in the low and middle speed ranges. Therefore, conventionally, for example, Japanese Patent Publication No. 47-3
As disclosed in Japanese Patent No. 2850, the carburetor and the combustion chamber are communicated with each other by high-speed and low-speed intake pipes, the low-speed intake pipe is formed longer than the high-speed intake pipe, and the openings on the carburetor side of these intake pipes are formed. A low-speed throttle valve and a high-speed throttle valve are provided near the end, and by interlocking the high-speed throttle valve to open when the low-speed throttle valve opens a predetermined angle or more, high speed is achieved in both low and high speed cases. Trying to get torque.

[Problems to be Solved by the Invention]

However, in such a structure in which the low-speed throttle valve and the high-speed throttle valve are interlocked with each other, when the opening degree of the low-speed throttle valve is increased in order to accelerate an automobile or the like from a low-speed running state, the high-speed throttle valve is simultaneously opened. The intake air is introduced from both intake pipes. Therefore, the intake flow velocity becomes slow, and the characteristics of the low-speed intake pipe cannot be fully utilized, so that it is difficult to obtain sufficient acceleration performance. The present invention has been made in view of the above circumstances, and it is possible to obtain high torque in both low speed and high speed, and to improve the acceleration performance in the low speed operation range. A device is provided.

[Means for Solving the Problems]

The intake device for a multi-intake valve type engine according to the present invention has an intake passage configured by a first intake branch passage adapted to a low speed operation range and a second intake branch passage adapted to a high speed operation range. A first throttle valve and a second intake valve that open an upstream side end of the intake air into the intake distribution box and control the amount of intake air flowing through the first intake branch path and the second intake branch path upstream of the intake flow from the intake distribution box. A secondary throttle valve that controls the amount of intake air flowing through the branch passage is provided, and the primary throttle valve is a manual valve that is opened and closed by accelerator operation, and the secondary throttle valve detects that the engine is operating at low speed or low output. An automatic valve that closes the secondary intake branch in conjunction with the means, and the first intake branch and the second intake branch are formed in the cylinder head and an intake pipe extending from the intake distribution box to the cylinder head. And each intake port By forming the intake pipe of the first intake branch passage longer than the intake pipe of the second intake branch passage, the length of the first intake branch passage and the second intake branch passage is changed, and both of these intake branch passages are secondary throttles. The structure is such that fuel is supplied also to the secondary intake branch passage on the downstream side of the valve.

[Action]

In the present invention, even if the opening degree of the primary throttle valve is increased,
When the engine is in the low speed or low power operating state, the second intake branch passage is closed, and the intake air is introduced into the combustion chamber only through the first intake branch passage adapted to the low speed operation range.

Further, the intake valve connected to the second intake branch passage is exposed to the air-fuel mixture.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view showing a part of an engine provided with an intake device for a multi-intake valve type engine according to the present invention, and FIG. 2 is a plan view of the same. In FIG. 1, reference numeral 1 denotes an engine body of a four-cylinder engine, which includes a combustion chamber 5 formed by a cylinder 2, a cylinder head 3 and a piston 4.
have. The combustion chamber 5 has two intake ports 6 and 6.
And two exhaust ports 7 and 7 are opened and opened and closed by intake valves 8 and 8 and exhaust valves 9 and 9, respectively. 1
Reference numeral 0 denotes a known valve mechanism, which opens and closes the intake valve 8 and the exhaust valve 9 at regular times.

The first intake branch passage 11 and the second intake branch passage 12 are connected to the intake ports 6 and 6 for each cylinder, and the other ends of the intake branch passages 11 and 12 are connected to these branch passages. An opening is made in the intake distribution box 14 for supplying fresh air. That is, the first and second intake branch passages 11 and 12 extend from the intake distribution box 14 to the combustion chamber 5
Constitutes an intake passage leading to. Here, the second intake branch passage 12 communicates with the bottom surface of the intake distribution box 14, and the first intake branch passage 11 penetrates the bottom surface and communicates with the upper portion inside the intake distribution box 14. Thus, the length of the first intake branch passage 11 is set to be slightly longer than that of the second intake branch passage 12, and is adapted to the relatively low speed operation range of the engine body 1, and the second intake branch passage 12 is relatively high speed operation range. For example, it is set to match the maximum output speed. Both intake branch paths 11 and 12 are connected to the intake distribution box 14
And an intake port 6 formed in the cylinder head 3 and an intake pipe 16 extending from the cylinder head 3 to the cylinder head 3. Then, the first intake branch 1 in the intake pipe 16
The length of the first intake branch passage 11 and the length of the second intake branch passage 12 are changed by forming the portion forming 1 to be longer than the portion forming the second intake branch passage 12. The first intake branch passage 11 and the second intake branch passage 12 are communicated with each other by a communication hole 17 near the intake valve 8. Reference numeral 18 denotes an injection nozzle of the electronically controlled fuel injection device which opens in the communication hole 17. That is, the first intake branch passage 11 and the second intake branch passage 12 are formed in a structure in which fuel is also supplied to the second intake branch passage 12 on the downstream side of the secondary throttle valve 24.

An intake pipe 19 is attached to the upstream side of the intake distribution box 14, and the intake pipe 19 communicates with the atmosphere via an intake flow rate measuring device (not shown). Reference numeral 23 is a primary throttle valve provided in the intake pipe 19, and controls the amount of intake air flowing through the first intake branch passage 11 and the second intake branch passage 12 branched in the intake distribution box 14. The primary throttle valve 23 is a manual valve that is manually operated by an operator such as an accelerator pedal. Reference numeral 24 is a secondary throttle valve provided in the second intake branch passage 12 for controlling the amount of intake air flowing through the second intake branch passage 12,
It is an automatic valve that works in conjunction with a detecting means to be described later and closes the second intake branch passage 12 when the engine is running at low speed or at low output.
More specifically, the secondary throttle valve 24 is configured to be opened by the diaphragm device 25 when the exhaust pressure is high. The diaphragm device 25 is provided on the diaphragm 25c held by the housing 25a and biased in a certain direction by a spring 25b, a rod 25d fixed to the diaphragm 25c, a rod 2d and a valve shaft of the secondary throttle valve 24. It is composed of a drive link 25e and the like that connect the rotary lever 24a with the rotary lever 24a. Reference numeral 26 is an exhaust pressure passage for introducing the exhaust pressure of the engine into the chamber on the side opposite to the spring in the housing 25a, and a filter 27 is provided in the middle thereof.
Is provided. Reference numeral 28 is a check valve for introducing the atmosphere into the exhaust port 7 through the filter 29 when the internal pressure of the exhaust pressure passage 26 becomes negative due to pulsation.
It is for preventing clogging of No. 7. That is, the diaphragm device 25 constitutes detection means for detecting whether the engine is in a low speed or low output state, or in a high speed or high output state depending on the exhaust pressure.
A drive means is configured to close the secondary throttle valve 24 when the engine is in a low speed or low output state, and to open the secondary throttle valve 24 when the engine is in a high speed or high output state.

Next, the operation of this embodiment will be described. When the primary throttle valve 23 is at the idling opening during the operation of the engine, the exhaust pressure of the engine is low and the secondary throttle valve 24 is substantially fully closed. The fuel is mixed by the injection nozzle 18 through the first intake branch passage 11 to form a mixture, which flows into the combustion chamber 5 during the intake stroke of the engine.

When the primary throttle valve 23 is opened slightly larger to increase the engine output, the intake flow rate increases. Intake is the intake distribution box 14
Since only the first intake branch passage 11 passes through, the intake flow velocity is sufficiently large, and the dynamic pressure and the effect of air column vibration generated in the first intake branch passage 11 cause the intake valve 8 to open immediately before opening. The intake pressure in the vicinity is kept relatively high. Therefore,
The blowback from the inside of the combustion chamber 5 is controlled, and the intake air is efficiently taken into the combustion chamber 5, so that a relatively high torque can be obtained. Here, since no throttle valve or the like is provided in the first intake branch passage 11, the air column vibration generated in the first intake branch passage 11 can be made less likely to be damped, and this air column vibration can improve the efficiency. Intake can be introduced well. When the intake flow velocity in the first intake branch passage 11 becomes higher than a predetermined value, a contraction phenomenon occurs in the air flow near the opening of the intake valve 8 and the intake resistance rapidly increases. At this time, since the first intake branch passage 11 and the second intake branch passage 12 are communicated with each other by the communication hole 17 in the vicinity of the intake valve 8, part of the intake air from the first intake branch passage 11 is part of the second intake branch passage. The commutation into the passage 12 and the peak of the intake air flow rate can be shifted to the higher load side. Even when the secondary aperture 24 is closed in this way,
Since the air-fuel mixture flows into the second intake branch passage 12 downstream of the secondary throttle valve 24, the intake valve 8 connected to the second intake branch passage 12 is exposed to the air-fuel mixture. That is, the intake valve 8 can be reliably cooled by the fuel.

When the primary throttle valve 23 is further opened greatly, the engine speed increases, and the exhaust pressure increases, this exhaust pressure is introduced into the diaphragm device 25 from the exhaust pressure passage 26. Therefore, the rod 25d projects outward and it is detected that the engine is in a high speed or high power operation state, and the drive link 25e also opens the secondary throttle valve 24, so that the intake air flows only through the first intake branch passage 11. Without second intake branch 1
2 is also sucked into the combustion chamber 5. At this time, the intake air is introduced into the second intake branch passage 12 more efficiently due to the air column vibration adapted to the high speed operation range near the maximum output speed. That is, since the first intake branch passage 11 and the second intake branch passage 12 are independent of each other and only communicate with each other in the vicinity of the intake valve 8, air column vibration generated in both intake branch passages is generated. Minimize interference with each other. At this time also, the air-fuel mixture is sucked into the combustion chamber through the intake ports 6 and 6. That is, both intake valves 8 and 8 are cooled by the air-fuel mixture.

Further, even when the opening degree of the primary throttle valve 23 is widened in order to accelerate the engine from the low speed operation range, the secondary throttle valve 24 keeps increasing the rotational speed of the engine and increasing the exhaust pressure. Since the engine is not opened, intake air can be introduced only from the first intake branch 11 when the engine is in the low speed operation range. Therefore, the amount of intake air can be increased by sufficiently utilizing the characteristics of the first intake branch passage 11 adapted to the low speed operation range, such as maintaining a state where air column vibration occurs. As a result, as in the past, when the engine is still in the low speed rotation range at the time of acceleration, the two intake branch passages are opened at the same time, and the intake flow velocity slows down to obtain the intake effect due to the air column vibration. The acceleration performance in the low speed operation range can be improved as compared with the difficult structure.

〔The invention's effect〕

As described above, according to the present invention, the intake passage is constituted by the first intake branch passage adapted to the low speed operation region and the second intake branch passage adapted to the high speed operation region, and the upstream side of both intake branch passages. An end portion is opened in the intake distribution box, and a primary throttle valve for controlling the amount of intake air flowing through the first intake branch path and the second intake branch path upstream of the intake distribution box and a second intake branch path are provided. A secondary throttle valve that controls the amount of intake air that flows is provided, the primary throttle valve is a manual valve that is opened and closed by accelerator operation, and the secondary throttle valve is linked to the detection means that detects whether the engine is operating at low speed or low output. As a result, an automatic valve is used to close the second intake branch passage.Therefore, during low-speed or low-power operation of the engine, even if the opening degree of the primary throttle valve is increased, the first intake branch that is suitable for low-speed operation Can be introduced into the combustion chamber only from the road, and has high speed In the time of high output operation can be introduced intake from the second intake branch.

Therefore, in the low speed operation region, the intake air is guided to the combustion chamber only through the first intake branch passage to increase the intake flow velocity, and the first intake branch passage is adapted to the low speed operation region. Since the two intake branches are adapted to the high speed operation range, intake air can be efficiently introduced by the vibration of the air column, so that high torque can be obtained in the low speed / high speed operation range. Moreover, even if the opening of the primary throttle valve is increased in order to accelerate the engine from the low speed operation range, the secondary throttle valve is not opened and the intake air can be introduced only from the first intake branch passage. It is possible to make full use of the characteristics of the first intake branch passage adapted to the operating range to increase the intake amount and improve the acceleration performance in the low speed operating range. Further, the first intake branch passage and the second intake branch passage are respectively configured by an intake pipe extending from the intake distribution box to the cylinder head and an intake port formed in the cylinder head, and the intake pipe of the first intake branch passage is formed. By changing the length of the first intake branch and the second intake branch by making the intake pipe longer than the intake pipe of the second intake branch, the length of both intake branches can be adapted to the low speed operating range and the high speed operating range. Each setting can be performed without restriction by avoiding interference with the engine. Therefore, the degree of freedom in design is increased, and it is possible to set the first intake branch passage and the second intake branch passage to be surely adapted to the low speed operation range and the high speed operation range, respectively. High torque can be obtained regardless of the high speed.

Furthermore, since the first intake branch passage and the second intake branch passage are formed in a structure in which fuel is also supplied to the second intake branch passage downstream of the secondary throttle valve, The continuous intake valves are exposed to the air-fuel mixture, and the intake valves can be reliably cooled by the fuel.

[Brief description of drawings]

FIG. 1 is a sectional view showing a part of an engine provided with an intake device for a multi-intake valve type engine according to the present invention, and FIG. 2 is a plan view of the same. 2 ... Cylinder, 5 ... Combustion chamber, 11 ... First intake branch, 12 ... Second intake branch, 14 ... Intake distribution box, 23
...... Primary throttle valve, 24 ...... Secondary throttle valve, 25 ...... Diaphragm device.

Claims (1)

[Claims] 1. An intake passage communicating with a combustion chamber is composed of a first intake branch passage and a second intake branch passage, and upstream end portions of these both intake branch passages are opened in an intake distribution box. The length of the intake branch passage is set to be longer than the second intake branch passage so as to be adapted to the low speed operation range, and the length of the second intake branch passage is set to be adapted to the high speed operation area. A primary throttle valve that controls the amount of intake air flowing through the intake branch passage and the second intake branch passage on the upstream side of the intake flow from the intake distribution box, and a secondary throttle valve that controls the amount of intake air flowing through the second intake branch passage are provided. The primary throttle valve is a manual valve that is opened / closed by an accelerator operation, and the secondary throttle valve is linked to a detecting means for detecting that the engine is in a low speed or low output operation state. It becomes an automatic valve that closes the branch, and The second intake branch passage is configured by an intake pipe extending from the intake distribution box to the cylinder head and an intake port formed in the cylinder head, and the intake pipe of the first intake branch passage is defined by the intake pipe of the second intake branch passage. By making it longer than the intake pipe, the lengths of the first intake branch passage and the second intake branch passage are changed, and both of these intake branch passages also supply fuel to the second intake branch passage downstream of the secondary throttle valve. An intake device for a multi-intake valve engine, characterized in that the intake device is formed in such a structure.