JP3511384B2 - Engine intake system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake device for an engine for guiding intake air to a combustion chamber of the engine, and more particularly to a structure of an intake passage. 2. Description of the Related Art Conventionally, as a four-stroke engine, in order to increase fuel efficiency and reduce harmful components in exhaust gas, the air-fuel ratio is made larger than the stoichiometric air-fuel ratio (the mixture is made thinner).
Some are configured to perform lean combustion. In this type of engine, various techniques have been taken so that combustion can be performed quickly and reliably even if the air-fuel mixture is made thin.
As a method, a horizontal vortex or a vertical vortex is generated in the combustion chamber using the flow velocity when the intake air enters the combustion chamber to agitate the air-fuel mixture, or the horizontal vortex or the vertical vortex is used to enter the combustion chamber. For example, the air-fuel mixture may be caused to flow in a layered manner so that the air-fuel mixture is concentrated around the spark plug more than other parts. [0003] In generating such a swirl of intake air in the combustion chamber, the opening direction and shape of the intake port are changed in order to give an opportunity to generate the swirl.
In the case of an engine using one intake valve, a passage that selectively closes the intake passage of the other intake valve so that a mixture having a high flow velocity to generate a vortex flows from one intake valve into the combustion chamber. A switching mechanism was provided. [0004] However, in the above-described lean-burn engine, there is a limit in increasing the intake efficiency and improving the output. The reason for this is that a trigger for generating a vortex in the combustion chamber is required in a portion of the intake port near the combustion chamber. That is, the intake resistance increases due to the trigger. On the other hand, as an engine in which the intake resistance is suppressed and the intake efficiency is increased, the applicant of the present invention has filed Japanese Patent Application No. 2-235.
No. 267 has previously proposed. In this engine, three intake valves were provided for each cylinder, and the intake ports for each intake valve were formed linearly. In addition, the intake passage formed in the cylinder head is branched into three passages for each intake valve at an upstream portion connected to the throttle valve. SUMMARY OF THE INVENTION It is an object of the present invention to provide an intake system for an engine capable of performing lean combustion on an engine with improved intake efficiency in order to obtain high output while reducing fuel consumption. [0007] An intake system for an engine according to the present invention is provided with a plurality of intake passages that open to a combustion chamber, and each intake passage extends from the combustion chamber to the vicinity of a throttle valve individually. The throttle valve side openings of the plurality of intake passages are formed side by side in a direction substantially orthogonal to the direction of movement of the edge of the throttle valve. The opening position on the throttle valve side of at least one of the intake passages in the passage,
The opening position of the other intake passage is deviated in the moving direction of the edge of the throttle valve from the opening position , and these openings are provided at the end of the throttle valve.
When viewed from a direction substantially perpendicular to the edge movement direction,
It is formed so as to overlap . When the throttle valve is at a low or medium opening, the air-fuel mixture mainly flows through the intake passage located on the opening side of the throttle valve. Therefore, the flow rate of the air-fuel mixture differs between the plurality of intake passages. And the intake air flows unevenly into the combustion chamber
A vortex is formed in the combustion chamber consisting of the intake flow . Also slot
Is located on the opening side of the throttle valve when the throttle valve opens
Before the intake passage is fully opened, the flow of the other intake passage
The intake air amount can be increased. An embodiment of the present invention will be described below in detail with reference to FIGS. FIG. 1 is a front view of a motorcycle engine provided with an air intake device according to the present invention. FIG. 2 is a side view of a motorcycle provided with an intake device according to the present invention, FIG. 3 is a view showing a state where a combustion chamber of an engine is viewed from a piston side, and FIG. 4 is a view IV-IV in FIG.
5 is a cross-sectional view taken along line VV in FIG. 1, and FIG. 6 is a view taken in the direction of arrow A in FIG. 1. In these figures, reference numeral 1 denotes a parallel multi-cylinder DOHC type engine.
This is provided and two exhaust valves 3 are provided. 1
a is a crankcase of the engine 1, and 1b is a cylinder block. 1c supports the intake valve 2 and the exhaust valve 3, and also includes a throttle valve device and an exhaust pipe 4 described later.
Is connected to the cylinder head, and 1d is a cylinder head cover. 1e is an intake cam shaft for driving the three intake valves 2 via a lifter, and 1f is an exhaust cam shaft for driving the two exhaust valves 3 via a lifter. 1 is extended in a direction perpendicular to the paper surface,
It is rotatably supported by the cylinder head 1c and the cylinder head cover 1d. Note that the valve shafts of the three intake valves 2 are respectively arranged on a plane orthogonal to the intake cam shaft 1e. That is, the valve shafts are parallel to each other when viewed from the front of the engine. The engine 1 is mounted on a motorcycle 5 with the cylinder portion tilted forward as shown in FIG.
The body structure of the motorcycle 5 shown in FIG. 2 is equivalent to that of a conventionally known motorcycle, and a front fork 7 having a front wheel 6 is steerably supported by a head pipe 1b of a frame 1a. In the motorcycle 5, a radiator 8 is mounted in front of the engine 1. As shown in FIGS. 1 and 4, intake ports 9, 10, 11 are formed for each intake valve 2 and exhaust ports 12, 13 are provided for each exhaust valve 3 in a cylinder head 1c of the engine 1. Is formed. The intake ports 9, 10, 11 are formed such that the cross-sectional shape of the intake passage formed therein is substantially equal from the upstream end to the opening on the combustion chamber 14 side. That is, the intake passages in each of the intake ports 9, 10, 11 are formed in a circular cross section over the entire area. Further, these intake ports 9 to 11 are linearly extended to the combustion chamber side bent portions at substantially equal angles from the upstream open ends.
In other words, the straight portion is substantially parallel as viewed from the side of the engine as shown in FIG. When the upstream portions of the three intake ports 9 to 11 are formed linearly and substantially in parallel, the inertial force acting on the intake can be made substantially equal in each of the intake ports 9 to 11. . Further, the central intake port 10 of the three intake ports 9 to 11 is formed shifted from the intake ports 9 and 11 on both sides to the lower side of the engine so as to correspond to the opening position on the combustion chamber 14 side. ing. As shown in FIG. 3, a spark plug 1g is provided at the center of the combustion chamber 14, and the intake ports 9 to 11 and the exhaust ports 12, 13 surround the spark plug 1g. Are located in Reference numeral 15 denotes a throttle valve device. The throttle valve device 15 has a plate-shaped slide valve body 16 and is connected to the engine 1 via an intake manifold 17 fixed to the cylinder head 1c. Reference numeral 18 denotes a rubber joint for connecting the throttle valve device 15 to the intake manifold 14. Reference numeral 19 denotes an intake pipe connected to the upstream side of the intake flow of the throttle valve device 15, and the intake pipe 19 is provided with a fuel injector 20. And is communicated to the atmosphere via an air funnel 21. In the throttle valve device 15, a drive arm 15a is connected to an open end of a valve body 16. The drive arm 15a is rotated in a direction indicated by an arrow A in FIG. 16 is slid in the direction indicated by arrow B to open and close the intake passage 15b. The drive arm 15a is connected to an accelerator grip (not shown), an electric drive device, or the like, and is configured to be rotationally driven. Also, one shaft for driving the drive arm 15a is provided for each cylinder, and each shaft is connected via a tuning mechanism (not shown). A pulley connected to a throttle grip or the like (not shown) is mounted on one of the shafts. That is, when the throttle grip is operated, all the drive arm shafts rotate, and all the valve bodies 16 of one throttle valve device 15 provided per cylinder open and close simultaneously. Further, an intake passage 15b in the throttle valve device 15 is formed in an elongated hole shape as shown in FIG. As shown in FIG. 6, the valve body 16 is formed in a square shape when viewed from the upstream side of the intake flow, and its width dimension and dimension in the sliding direction are set larger than the opening dimension of the intake passage 15b. That is, the valve element 16
Is changed as shown by two-dot chain lines a and b in FIG. 6, the flow rate of the intake air passing through the intake passage 15b is changed. The intake manifold 17 has passage forming holes 17a to 17c communicating with the intake ports 9 to 11 of the cylinder head 1c, respectively. The passage forming holes 17a to 17c are provided in the intake manifold 1
When the throttle valve device 15 is connected to 7, the upstream end is communicated with the intake passage 15 b of the throttle valve device 15. That is, the passage forming holes 17a to 17c and the intake ports 9 to 11 constitute an intake passage downstream of the throttle valve device 15. Each of the passage forming holes 17a to 17c is formed in a circular cross section as shown in FIG. 5, and its downstream opening is formed so that a step is not formed between the passage forming holes 17a to 17c and the intake ports 9 to 11. Has an inner diameter and an opening position.
That is, among the three passage forming holes 17a to 17c, the passage forming hole 17b communicating with the central intake port 10 is arranged such that the intake port 10 is positioned lower than the other intake ports 9 and 11 in the engine. Passage forming holes 1 on both sides
7a and 17c are formed to be shifted downward in FIG. That is, these passage forming holes 17a-1
7c is the moving direction of the valve body 16 as shown in FIG.
Are formed side by side in a direction substantially orthogonal to each other, and the opening position on the throttle valve device side in the center passage forming hole 17b is, as shown in FIGS.
The edge of the valve element 16 from the opening position of 7a, 17c (FIG. 6)
Are shifted in the movement direction (the vertical direction in FIGS. 5 and 6) of the lowermost edge on the closed side . Also,
Openings of passage forming holes 17a to 17c on the throttle valve device side
Is a direction substantially perpendicular to the moving direction of the edge of the valve body 16.
Are formed so as to partially overlap each other when viewed from above. Further, each of the passage forming holes 17a to 17c is
As shown in FIG. 1, the opening diameter is formed so as to gradually increase from the downstream opening to the upstream, and the opening edge of each throttle valve device side is rounded on the inner wall and enlarged to have a large diameter. It is open. The opening dimension of the opening edge portion on the throttle valve device side in the central passage forming hole 17b is set larger than the passage forming holes 17a and 17c on both sides. These passage forming holes 17a to 17
The opening edge of the throttle valve device side c is indicated by reference numeral 17d in FIG. As the injector 20, a conventionally well-known one is employed, and is configured to inject fuel based on a predetermined injection timing. And this injector 2
Numeral 0 is inclined with respect to the flow direction of the intake air so as to inject fuel toward the valve element 16 of the throttle valve device 15. As shown in FIGS. 1 and 4, the mounting direction of the injector 20 is such that the injection direction is on the opening side of the throttle valve device 15 and the passage forming hole 17 b
And the passage forming hole 17c. In FIG. 1, reference numeral 22 denotes a piston of the engine 1, and reference numeral 23 denotes a crankshaft. FIG.
An alternate long and short dash line C indicates the cylinder axis. The engine 1 shown in FIG. 1 has a crankcase 1a and a cylinder block 1b.
Is inclined by an angle θ with respect to the virtual line E. The imaginary line E is orthogonal to an imaginary line G connecting the intersection F between the cylinder axis C and the mating surface D and the axis of the crankshaft 23. The cylinder axis C is offset from the axis of the crankshaft 23 by the dimension L. That is, when the cylinder axis C is offset from the axis of the crankshaft 23 in order to reduce the piston side pressure, in the engine 1 of this embodiment, the mating surface D is inclined with respect to the imaginary line E. Is going. In this way, the cylinder is positioned closer to the crankshaft 23 than when the cylinder is simply moved in parallel along the imaginary line E to offset the cylinder axis C. (The length in the left-right direction in FIG. 1) can be reduced. When the cylinder portion of the engine 1 is raised as described above, the space behind the radiator 8 shown in FIG. 2 can be widened. Next, the operation of the intake device configured as described above will be described. When the engine 1 is in the idling state, the valve element 16 of the throttle valve device 15 is held in a state of being slightly opened from the fully closed position shown in FIG. Then, the valve body 16 is slid and gradually opened to gradually increase the amount of intake air supplied to the engine 1, and fuel is injected from the injector 20 by an amount corresponding to the amount of intake air to increase the engine speed. I do. The intake air amount is directly or indirectly detected, but in the present embodiment, it is calculated by calculating from the sliding amount of the valve body 16 and the engine speed. When the engine speed is in the low or middle rotation range, in other words, until the valve body 16 slides and its edge reaches the position indicated by the two-dot chain line a in FIG. Since the passage forming holes 17a and 17c on both sides of the passage forming holes 17a to 17c are located just behind the valve body 16, the fuel-mixed mixture mainly forms the central passage from the opening side of the throttle valve device 15. It flows into the hole 17b. At this time, the three intake ports 9, 1
The air-fuel mixture mainly flows to the central intake port 10 of 0 and 11, and the air-fuel mixture flows at the central intake port 10 at the highest speed. Become like This vertical vortex has a richer mixture nearer the spark plug, and has a smaller thickness farther away. That is, even if the air-fuel ratio of the air-fuel mixture is made larger than the ideal air-fuel ratio, a miscible fuel or a reduction in the combustion speed may occur because a rich air-fuel mixture layer is formed around the ignition plug. Combustion can be performed without the need. When the throttle valve device 15 is opened, the valve body 1 is opened.
6, the center passage forming hole 17b is in a fully opened state when the edge of FIG.
Before this, the air-fuel mixture also flows into the passage forming holes 17a, 17c on both sides of the intake manifold 17, and the amount of air-fuel mixture supplied to the engine 1 increases, and the engine speed increases. The throttle valve device 15 is fully opened when the edge of the valve body 16 is positioned at a position indicated by a two-dot chain line b in FIG. Therefore, in the intake device configured as described above, when the throttle valve device 15 is at a low or medium opening, the air-fuel mixture mainly flows into the passage forming hole 17b located on the opening side of the throttle valve device 15. As a result, a vertical vortex is generated in the combustion chamber 14 such that the air-fuel mixture around the ignition plug becomes rich. For this reason, since there is no need to form a trigger for vortex formation in the vicinity of the combustion chamber 14 in performing lean combustion, it is possible to suppress an increase in intake resistance and increase intake efficiency. The passage forming hole 17b located on the opening side of the throttle valve device 15 and the other passage forming holes 17a and 17b are formed side by side in a direction substantially perpendicular to the direction in which the edge of the valve body 16 moves. And
The opening position of the passage forming hole 17b on the throttle valve device side is
The opening of the passage forming holes 17a and 17c is deviated in the moving direction of the edge of the valve body 16 from the opening position , and these openings are
When viewed from a direction substantially perpendicular to the moving direction of the edge, a part of each
Are formed so as to overlap with each other, so that the opening degree of the throttle valve device 15 increases from the above-described state,
Before the passage forming hole 17b is fully opened, intake air flows into the combustion chamber 14 from the other passage forming holes 17a and 17c. That is, when the throttle valve device 15 is opened from the fully closed position to the fully open position, the intake air mainly flows through the passage forming holes 17b and a tumble is generated in the combustion chamber 14, so that the intake air flows into all the passage forming holes 17a to 17a. 17c
To the state of flowing. The time at which these operating states are switched is determined by the other passage forming holes 17a, 1
7c is determined in accordance with the position (position of the edge of the valve body 16 in the moving direction). Therefore, by changing the position where the other passage forming holes 17a and 17c are formed at the time of design, it is possible to set the timing at which the above-mentioned two operating states are switched. In this embodiment, an example is shown in which only one injector 20 is provided on the upstream side of the throttle valve device 15. However, as shown by a two-dot chain line in FIGS. An auxiliary injector 20a may be provided on the downstream side. Although this auxiliary injector 20a is drawn so as to inject fuel into the passage forming hole 17b at the center of the intake manifold 17, its mounting position and quantity can be changed as appropriate. For example, fuel can be injected from auxiliary injector 20a into an intake passage having a relatively large passage cross-sectional area and a large intake flow rate. In particular, during the acceleration, the fuel is injected from the auxiliary injector 20a into the passage forming hole 17b or the like, so that the acceleration performance can be improved. In this embodiment, the intake manifold 1
7 with the passage forming holes 17b on both sides.
Although an example is shown in which the openings are located closer to the opening of the throttle valve device 15 than a and 17c, the opening positions and opening dimensions of the passage forming holes 17a to 17c are appropriately changed as shown in FIGS. can do. FIG. 7 is a cross-sectional view showing another embodiment of the intake manifold. In FIG. 7, the same or equivalent members as those described in FIG. 5 are denoted by the same reference numerals, and detailed description is omitted. 7A and 7B show an example in which the passage forming holes 17a and 17c on both sides are positioned closer to the opening of the throttle valve device 15 than the center passage forming hole 17b. In FIG. 3B, the three passage forming holes 17a to 17c have the same diameter. In this manner, when the throttle valve device 15 is at a low or medium opening degree, a vertical vortex is formed in the combustion chamber as in the above-described embodiment. FIG. 7C shows an example in which the center passage forming hole 17b and the left passage forming hole 17c are positioned on the opening side of the throttle valve device 15. Then, the passage forming hole 1 on the left side
7c is formed larger in diameter than the other passage forming holes. When the passage forming hole is formed in this way, the throttle valve device 15
Is low and medium opening, the air-fuel mixture mainly flows into the center and left intake ports 10 and 11 among the three intake ports 9 to 11, and a lateral vortex is generated in the combustion chamber. When the air vortex is generated, the air-fuel mixture is efficiently stirred. Therefore, even if the air-fuel mixture is made thin, the combustion speed is hardly reduced. Further, when fuel is supplied when the lateral vortex is generated, a mixture layer containing a large amount of fuel is formed around the ignition plug at the center of the combustion chamber, so that combustion can be performed more efficiently. Become. FIG. 7D shows an example in which only the left passage forming hole 17c is positioned on the opening side of the throttle valve device 15. In this example, the three passage forming holes 17a to 17c have the same diameter. Even in this case, a lateral vortex is generated in the combustion chamber as in the example shown in FIG. Further, in each of the above-described embodiments, the intake valve is set to 3
Although the description has been given of the example in which the number of intake valves is one, the present invention is not limited to such a limitation, and the number of intake valves can be appropriately changed. FIG. 8 (a), the showing the intake manifold in the case of using two intake valves (b). FIG. 8 is a sectional view showing another embodiment of the intake manifold when there are two intake valves. FIG.
The intake manifold 17 shown in (b) has passage forming holes 31 and 32 communicating with intake ports (not shown) for each intake valve.
Are formed on the left and right. And one of the passage forming holes 3
1 is positioned on the opening side of the throttle valve device 15 with respect to the other passage forming hole 32. In FIG. 3A, the passage forming hole 31 closer to the opening side of the throttle valve device 15 has a larger diameter than the other. Even in this case, when the throttle valve device is at a low and medium opening degree, a lateral vortex is generated in the combustion chamber. Further, the mounting position of the throttle valve device 15 can be changed as shown in FIG. 9, and as shown in FIG. 10, the throttle valve device can be changed to a conventionally known butterfly valve type. You can also. FIG. 9 is a sectional view showing another embodiment in which the position of the throttle valve device is changed, and FIG. 10 is a sectional view showing another embodiment using a butterfly valve type throttle valve device. In these figures, the same or equivalent members as those described in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted. The throttle valve device 15 shown in FIG.
The drive arm 15a is located on the side opposite to the cylinder head 1c, and the valve body 16 is inclined at an angle to the flow direction of the intake air flow. By doing so, it is possible to prevent the drive mechanism (not shown) of the throttle valve device 15 from interfering with the cylinder head 1c. Further, as the opening degree of the valve body 16 increases, the influence of the difference in the opening position of the passage forming hole becomes less likely to be affected, so that the air-fuel mixture flows into all the passage forming holes of the intake manifold 17. In FIG. 10, reference numeral 41 denotes a throttle valve device provided with a butterfly valve 42. The throttle valve device 41 includes passage forming portions 17a to 17a in the intake manifold 17.
The axis of the butterfly valve 42 is directed in the arrangement direction of 17c. As described above, even when the butterfly valve 42 is used, the same effects as those of the above-described embodiments can be obtained. Further, in each of the embodiments described above, the injector 20 is used to supply the fuel, but a conventionally known carburetor may be used instead of the injector. As described above, the intake system for an engine according to the present invention is provided with a plurality of intake passages that open to the combustion chamber, and each intake passage extends from the combustion chamber individually to the vicinity of the throttle valve. The throttle valve side openings of the plurality of intake passages are formed side by side in a direction substantially perpendicular to the moving direction of the edge of the throttle valve. The opening position of at least one of the intake passages on the throttle valve side is deviated from the opening position of the other intake passage toward the direction of movement of the edge of the throttle valve.
When viewed from a direction substantially perpendicular to the moving direction of the edges of
When the throttle valve is at a low or medium opening, the air-fuel mixture mainly flows into the intake passage located on the opening side of the throttle valve, so that the air-fuel mixture flows between the plurality of intake passages. And the intake air flows in a biased manner into the combustion chamber, and a vortex composed of the intake air flow is generated in the combustion chamber. Therefore, it is not necessary to form a vortex in the vicinity of the combustion chamber when lean-burning the engine. Therefore, it is possible to suppress an increase in intake resistance and to increase intake efficiency. For this reason, in the engine provided with the intake device according to the present invention, a high output can be obtained even when performing lean combustion. In addition, the slot
The intake passage on the opening side of the tor valve and the other intake passage
Align in the direction substantially perpendicular to the direction in which the edge of the throttle valve moves.
From the above-mentioned condition.
As the opening of the valve increases, the opening of the throttle valve
Before the mouth-side intake passage is fully opened,
Then, the intake air flows into the combustion chamber. That is,
The rottle valve opens from the fully closed position to the fully open position.
Intake air flows mainly through the intake passage on the opening side of the throttle valve.
The tumble or swirl in the combustion chamber
Then, it will shift to a state where the intake air flows through all the intake passages
Swell. The timing at which these operating states are switched
Position where another intake passage is formed (end of throttle valve
(The position of the edge in the moving direction). Accordingly
Change the position where the other intake passage is formed at the time of design.
When switching between the two operating states described above,
Period can be set, so the design
The degree of freedom increases.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of a motorcycle engine including an intake device according to the present invention. FIG. 2 is a side view of a motorcycle provided with the intake device according to the present invention. FIG. 3 is a view showing a state where a combustion chamber of the engine is viewed from a piston side. FIG. 4 is a sectional view taken along line IV-IV in FIG. FIG. 5 is a sectional view taken along line VV in FIG. FIG. 6 is a view as viewed in the direction of arrow A in FIG. 1; FIG. 7 is a sectional view showing another embodiment of the intake manifold. FIG. 8 is a cross-sectional view showing another embodiment of the intake manifold when there are two intake valves. FIG. 9 is a sectional view showing another embodiment in which the position of the throttle valve device is changed. FIG. 10 is a cross-sectional view showing another embodiment using a butterfly valve type throttle valve device. [Description of Signs] 1 Engine 1c Cylinder head 2 Intake valve 9 Intake port 10 Intake port 11 Intake port 14 Combustion chamber 15 Throttle valve device 16 Valve element 17 Intake manifold 17a Passage forming hole 17b Passage forming hole 17c Passage forming hole 20 Injector 31 Passage forming hole 32 Passage forming hole 33 Passage forming hole 34 Passage forming hole 35 Passage forming hole 36 Passage forming hole 41 Throttle valve device

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02B 31/02 F02B 17/00 F02D 9/14 F02M 35/104

Claims (1)

(57) [Claim 1] A plurality of intake passages that open to a combustion chamber are provided, and each intake passage is individually extended from the combustion chamber to the vicinity of a throttle valve, and the fuel supply device side is provided through the throttle valve. The plurality of intake passages are formed in such a manner that openings on the throttle valve side of the plurality of intake passages are arranged in a direction substantially perpendicular to a moving direction of an edge of the throttle valve, and at least one of these intake passages The opening position of the throttle valve side of the throttle valve is deviated from the opening position of the other intake passage toward the moving direction of the edge of the throttle valve.
When viewed from a direction substantially perpendicular to the moving direction of the edges of
An intake device for an engine, wherein parts are formed to overlap .