CN110318923B

CN110318923B - Intake structure for internal combustion engine used on saddle type vehicle

Info

Publication number: CN110318923B
Application number: CN201910195757.3A
Authority: CN
Inventors: 田中雅人; 广濑恭平; 森木悠介
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2018-03-30
Filing date: 2019-03-14
Publication date: 2021-12-28
Anticipated expiration: 2039-03-14
Also published as: CN110318923A; JP2019178626A; EP3546739A1; JP6680822B2; PH12019000135A1; BR102019004231A2; EP3546739B1

Abstract

An intake structure for an internal combustion engine (4) used on a saddle-type vehicle includes an upper rib (71), a lower rib (72), a left rib (73), and a right rib (74) that stand on an upper surface, a lower surface, a left surface, and a right surface, respectively, of an intake pipe (7), wherein an injector (81) is provided between one of the left rib (73) and the right rib (74) and the upper rib (71). The upper, lower, left and right ribs of the intake pipe increase the rigidity and mechanical strength of the intake pipe against vibration generated by the vehicle and vibration generated in the intake pipe, thereby increasing the vibration control capability of the intake pipe, and the injector can be positioned so as not to physically interfere with the ribs even if the upper rib (71) is provided on the intake pipe.

Description

Intake structure for internal combustion engine used on saddle type vehicle

Technical Field

The present invention relates to an intake structure for an internal combustion engine used on a saddle type vehicle, which includes an intake pipe that has high vibration controllability and is less harmful to the mounting of a fuel injection device.

Background

Some internal combustion engines used on motorcycles such as light-duty motorcycles (LMC) have a cylinder axis that is slightly inclined forward from a vertical plane. Such an internal combustion engine includes an intake pipe that extends between the carburetor and the cylinder head and has a pair of upper and lower reinforcing ribs that extend in a longitudinal direction of the intake pipe and integrally protrude from respective left and right side surfaces of the intake pipe. The air inlet pipe further includes a pair of streamlined ribs extending in the longitudinal direction of the air inlet pipe on respective upper and lower surfaces of the air inlet pipe. An internal combustion engine of this type is disclosed in, for example, patent document 1 shown below.

Unlike the fuel supply process in which the carburetor is used to supply the air-fuel mixture into the combustion chamber, the process of supplying the air-fuel mixture into the combustion chamber with the fuel injection device requires the injector to be provided in the intake pipe. If the latter process is employed in the internal combustion engine disclosed in patent document 1, the injector provided in the intake pipe tends to physically interfere with the rib on the intake pipe.

Therefore, when the intake pipe is provided with the rib, there is a need for a structure in which the injector and the injector mounting base are disposed so as not to physically interfere with the rib on the intake pipe.

A scooter type motorcycle is known in the art, which comprises a swingable power unit, the cylinder axis of which is oriented in the longitudinal direction of the motorcycle. The swingable power unit includes an intake pipe extending from a junction point between itself and the cylinder head and bent in a rearward direction of the motorcycle, and a throttle body disposed upstream of the intake pipe. Since the intake pipe is vibrated when the swingable power unit swings, it has been required that the intake pipe includes a structure that increases the vibration control capability of the intake pipe.

[ Prior Art document ]

[ patent document ]

Patent document 1: JP 2010-190083A (FIG. 2, FIG. 3, FIG. 7, FIG. 8)

Disclosure of Invention

[ basic problems to be solved by the present invention ]

The present invention has been made in view of the above-mentioned prior art. An object of the present invention is to provide an intake structure for an internal combustion engine used on a saddle-type vehicle, which increases the vibration control capability of an intake pipe; and the intake structure does not adversely affect the mounting of the injector and the like of the fuel injection device from the viewpoint of physical interference with the vibration control device for the intake pipe.

[ MEANS FOR SOLVING PROBLEMS ] to solve the problems

In order to achieve the above object, according to the present invention, there is provided an intake structure for an internal combustion engine used on a saddle-type vehicle, the intake structure having an upper rib, a lower rib, a left rib, and a right rib erected on an upper surface, a lower surface, a left surface, and a right surface of an intake pipe, respectively, wherein an injector is provided between the upper rib and one of the left rib and the right rib.

With the above arrangement, the upper, lower, left and right ribs of the intake pipe increase the rigidity and mechanical strength of the intake pipe against vibration generated by the vehicle and vibration generated in the intake pipe, thereby increasing the vibration control capability of the intake pipe, and the injector can be positioned without physically interfering with the ribs even if the upper rib is provided on the intake pipe.

In the above arrangement, the internal combustion engine may be included in a swingable power unit that is mounted on a vehicle body frame so as to swing together with the rear wheel, and the intake pipe may be bent and extend rearward of the vehicle from a joint point between the intake pipe and the cylinder head.

With this arrangement, in the swingable power unit in which the intake pipe is bent and extends rearward from the junction point between the intake pipe and the cylinder head, even if the distance between the cylinder head and the throttle body is greater than a predetermined value, the upper, lower, left and right ribs of the intake pipe effectively increase the rigidity and mechanical strength of the intake pipe against vibration generated by the vehicle and vibration generated in the intake pipe, thereby increasing the vibration controllability of the intake pipe, and even if the upper rib is provided on the intake pipe, the injector can be seated on the intake pipe without physically interfering with the ribs.

In the above arrangement, the ejector-side mounting hole may be provided between the upper rib and the other of the left and right ribs, and the ejector-side mounting hole may be provided on left and right sides of the upper rib, respectively.

With this arrangement, the rib for dealing with the vibration of the vehicle can be mounted on the intake pipe without physically interfering with the injector and the injection-side mounting hole.

In the above arrangement, the throttle body may be disposed upstream of the intake pipe, and at least the lower rib, the left rib, and the right rib may have respective rib heights that are gradually larger toward the downstream side in a direction in which air flows through the intake pipe.

With the above arrangement, even if the throttle body is connected to the upstream end of the intake pipe, the intake pipe is stably supported on the internal combustion engine.

In the above arrangement, the intake pipe may have a downstream portion that is connected to the cylinder head and has a connection area larger than a connection area of the intake pipe to an upstream portion of the throttle body.

With this arrangement, since the connection area of the intake pipe to the downstream portion of the cylinder head is larger than the connection area of the intake pipe to the upstream portion of the throttle body, the intake pipe is stably supported on the swingable power unit even if the throttle body is connected to the upstream portion of the intake pipe.

In the above arrangement, the upper rib and the lower rib may have respective rib heights such that the larger the curvature of the intake pipe, the larger the rib height is, except for a peripheral region around an insertion hole into which the injector is inserted.

With this arrangement, the swingable power unit in which the intake pipe is bent can make the intake pipe have higher vibration controllability by increasing the rib height according to the curvature of the intake pipe.

[ Effect of the invention ]

With the intake structure for an internal combustion engine used on a saddle-type vehicle according to the present invention, the upper, lower, left and right ribs of the intake pipe increase the rigidity and mechanical strength of the intake pipe against vibration generated by the vehicle and vibration generated in the intake pipe, thereby increasing the vibration control capability of the intake pipe, and the injector can be positioned without physically interfering with the ribs even if the upper rib is provided on the intake pipe.

Drawings

FIG. 1 is a right side view of a motorcycle including an air intake structure for an internal combustion engine for use on a saddle type vehicle in accordance with an embodiment of the present invention;

FIG. 2 is a side cross-sectional view of the internal combustion engine in the front portion of the power unit shown in FIG. 1, taken generally along the cylinder axis, with the internal combustion engine shown in the same orientation as FIG. 1;

FIG. 3 is a plan view of an internal combustion engine in the front of the power unit;

FIG. 4 is a perspective view of the internal combustion engine in the front of the power unit as viewed from a position slightly angled to the right behind the internal combustion engine;

FIG. 5 is a cross-sectional view of the cylinder head-side flange of the cylinder head and intake pipe, including the axis of the injector-side mounting hole, as viewed along line V-V in FIG. 3;

FIG. 6 is a vertical cross-sectional view of the air inlet conduit shown in FIG. 2, wherein the air inlet conduit is shown in the same orientation as in FIG. 2;

FIG. 7 is a plan view of the air intake duct mounted on the motorcycle as seen along line VII-VII in FIG. 6; and is

Fig. 8 is a bottom view of the intake duct mounted on the motorcycle as seen along line VIII-VIII in fig. 6.

Detailed Description

An intake structure of an internal combustion engine for use on a saddle type vehicle according to an embodiment of the present invention will be described below together with the accompanying drawings.

In the present specification and claims, directions such as forward, rearward, leftward, rightward, upward and downward, and other directions are expressed in correspondence with the directions with respect to the vehicle in which the air intake structure according to the present embodiment is included. The saddle type vehicle in the present embodiment specifically refers to a scooter type motorcycle (hereinafter simply referred to as "motorcycle").

In the drawings, reference symbol FR denotes a forward direction of the vehicle, LH denotes a leftward direction of the vehicle, RH denotes a rightward direction of the vehicle, and UP denotes an upward direction of the vehicle.

Fig. 1 to 8 relate to an embodiment of the present invention. Fig. 1 is a right side view of a motorcycle 1 according to the present embodiment, which includes an intake structure for an internal combustion engine used on a saddle type vehicle.

The motorcycle 1 incorporating the present embodiment includes a front vehicle body portion 1A and a rear vehicle body portion 1B interconnected by a floor portion 1C. The motorcycle 1 has a vehicle body frame 2 serving as a vehicle body skeleton, and the vehicle body frame 2 generally includes a down frame (down frame)21 and a pair of left and right main frames 22.

The down frame 21 extends downward from the head pipe 20 of the front vehicle body portion 1A. The left and right main frames 22 include respective lower frames (lower frames) 22a extending substantially horizontally rearward from the lower end of the down frame 21 and connected to the lower end of the down frame. The left and right main frames 22 further include a pair of left and right inclined portions 22b extending obliquely rearward and upward from the rear ends of the lower frames 22 a. The upper portion of the inclined portion 22b is bent and extends rearward into a pair of left and right horizontal portions 22c extending substantially horizontally.

A not-shown storage box is supported on the inclined portion 22b and the horizontal portion 22c of the main frame 22, and is covered by the rider seat 11 provided thereon.

In the front vehicle body portion 1A, the handle 12 is pivotally supported by the head pipe 20 and is disposed above the head pipe 20. The front fork 13 extends downward from the head pipe 20. The front wheel 14 is rotatably supported at the lower end of the front fork 13.

The power unit support bracket 23 protrudes rearward from the inclined portion 22b of the main frame 22. A swingable power unit (hereinafter simply referred to as "power unit") 3 is vertically swingably connected to and supported on a power unit support bracket 23 via a link 24 together with a rear wheel 15 operatively coupled to the power unit 3.

The motorcycle 1 includes an upper link support structure for the power unit 3.

In the front vehicle body portion 1A, the head pipe 20 and the down frame 21 are covered with the front cover 10a and the leg shield 10b which are located forward and rearward of the head pipe 20 and the down frame 21, respectively.

The floor portion 1C is provided by a lower frame 22a of the main frame 22. The lower frame 22a has an upper surface covered with the floor cover 10c, left and right surfaces covered with the respective longitudinal floor side covers 10d, and a lower surface covered with the lower cover 10 e.

In the rear vehicle body portion 1B, the fuel tank 16 is mounted on a horizontal portion 22c of the main frame 22 below a rear portion of the rider's seat 11. The inclined portion 22b and the horizontal portion 22c of the main frame 22 have left and right portions and a rear portion covered with the body cover 10 f. The front fender 10g is disposed above the front wheel 14.

The covers 10a to 10f are made of a suitable material. The under cover 10e should preferably, but not necessarily, be made of a resin material.

The power unit 3 includes an internal combustion engine 4 and a power transmission assembly 5 that extends rearward from the internal combustion engine 4 and includes a belt type continuously variable transmission 51. The rear wheels 15 are mounted on a rear shaft 52a, which is an output shaft of a reduction gear mechanism 52 provided in a rear portion of the power transmission assembly 5.

A rear shock absorber, not shown, is interposed between the rear portion of the power transmission assembly 5 and the horizontal portion 22c (i.e., the rear portion of the main frame 22).

The internal combustion engine 4 includes a crankshaft 41 that extends laterally (i.e., in the left-to-right direction of the motorcycle 1) and is rotatably supported by the power unit case 30. The internal combustion engine 4 has a cylinder block 42, a cylinder head 43, and a cylinder head cover 44 stacked in this order and fastened together. The cylinder block 42 has a cylinder axis C that is inclined forward to an almost horizontally disposed degree.

The power unit case 30 has a structure that can be divided into left and right case members. The left housing member integrally extends rearward as part of the power transmission assembly 5.

As shown in fig. 2, in the upper portion of the power unit 3, an intake pipe 7 is connected to an inlet of an intake port 45 defined in the upper portion of the cylinder head 43, which is inclined forward at a large angle. The intake pipe 7 is bent and extends rearward from a joint point 7a thereof to the cylinder head 43.

The exhaust pipe 6 is connected to an outlet of an exhaust port 46, which is defined in a lower portion of the cylinder head 43. The exhaust pipe 6 is connected to a catalyst converter 60 (fig. 1) having a substantially tubular shape. The catalyst converter 60 houses a catalyst 61, such as a three-way catalyst or the like, for example, for purifying exhaust gas emitted from the internal combustion engine 4.

The exhaust pipe 6 includes a front exhaust pipe 6A (fig. 1) and a rear exhaust pipe 6B. The front exhaust pipe 6A extends downward from the outlet of the exhaust port 46 and is connected to a catalyst converter 60, the center axis of the catalyst converter 60 being oriented in the lateral direction of the motorcycle 1. The rear exhaust pipe 6B connected to the catalyst converter 60 is bent rearward, extends rearward along the right side of the motorcycle 1, and is connected to a muffler 62 provided on the right side of the rear wheel 15.

The air cleaner 91 is mounted on the upper portion of the power transmission assembly 5. The intake pipe 7 is bent rearward from an inlet of an intake port 45 defined in an upper portion of the cylinder head 43 and is connected to the throttle body 9. An air cleaner 91 is provided upstream of the throttle body 9 and is connected to the throttle body 9 through a connecting pipe 90.

Fig. 2 is a side sectional view of the internal combustion engine 4 in the front portion of the power unit 3 shown in fig. 1, taken substantially along the cylinder axis C.

In fig. 2, vertical surfaces of the left half of the cylinder block 42, the cylinder head 43, and the head cover 44 of the internal combustion engine 4 are shown in vertical section. The power unit housing 30 has a right half housing (not shown) and a left half housing 30L, and a mating surface of the left half housing 30L that mates with the mating surface of the right half housing is shown in fig. 2 so as to face the viewer of fig. 2.

The power unit case 30 is constituted by a right half case (not shown) and a left half case 30L combined with each other. The right half case serves as the right half of the crankcase 30 a. The left half case 30L has a front portion serving as a left half of the crankcase 30a and extending rearward as a part of a power transmission assembly 5, which power transmission assembly 5 accommodates therein a power transmission device including a belt type continuously variable transmission 51, a reduction gear mechanism 52, and the like between the crankshaft 41 and a rear shaft 52a on which the rear wheels 15 are mounted.

The rotational power from the crankshaft 41 rotatably supported on the crankcase 30a of the internal combustion engine 4 is transmitted to the rear wheels 15 through the belt type continuously variable transmission 51 and the reduction gear mechanism 52 in the power transmission assembly 5.

The piston 31 is reciprocatably disposed in a cylinder bore 42a defined in the cylinder block 42. The piston 31 is coupled to a crank pin 41a on a crankshaft 41 in the crankcase 30a by a connecting rod 32.

A combustion chamber 49 is defined between a top surface of the piston 31 slidably fitted in a cylinder bore 42a defined in the cylinder block 42 and a combustion chamber upper limit surface (combustion chamber surface)43a of the cylinder head 43 facing the top surface of the piston 31.

According to the present embodiment, the internal combustion engine 4 includes an SOHC two-valve system including the valve operating mechanism 35 provided in the cylinder head 43. A cylinder head cover 44 is provided on the cylinder head 43 in covering relation to the valve operating mechanism 35.

In order to transmit power to the valve operating mechanism 35 in the cylinder head cover 44, an endless cam chain (not shown) is provided in a cam chain chamber (not shown) defined in the crankcase 30a, the cylinder block 42, and the cylinder head 43 on the side of the cylinder head 43 at one end of the crankshaft 41, and travels around the camshaft 36 and the crankshaft 41. When power is transmitted from the crankshaft 41 to the camshaft 36 through the endless cam chain, the camshaft 36 rotates in synchronization with the crankshaft 41 at half the speed of the crankshaft 41.

A spark ignition plug (not shown) is fitted in the cylinder head 43, and is inserted into the combustion chamber 49 on the other side of the cylinder head 43 at the other end of the crankshaft 41.

An intake port 45 and an exhaust port 46 are defined in a cylinder head 43 on a cylinder block 42 whose cylinder axis C is inclined forward so as to be positioned almost horizontally. The intake port 45 and the exhaust port 46 have ends that open at the combustion chamber upper limit surface 43a, and are curved and extend in directions vertically away from each other.

The intake port 45 has an upstream end that opens upward from the cylinder head 43 and is connected to the intake pipe 7, constituting a continuous intake passage 70. The throttle body 9 is connected to an upstream end of the intake pipe 7 that is bent and extends rearward.

The exhaust port 46 has a downstream end that opens downward from the cylinder head 43 and is connected to the exhaust pipe 6 (see fig. 1).

The tubular intake valve guide 37i is fitted in a curved outer wall 45a of the cylinder head 43, which defines the intake port 45 therein. The intake valve 38i is slidably supported by a tubular intake valve guide 37i to open and close an intake valve opening 47 defined in the cylinder head 43, and the intake port 45 communicates with a combustion chamber 49 through the intake valve opening.

The tubular exhaust valve guide 37e is fitted in the curved outer wall 46a of the cylinder head 43, which defines the exhaust port 46 therein. The exhaust valve 38e is slidably supported by a tubular exhaust valve guide 37e to open and close an exhaust valve opening 48 defined in the cylinder head 43, and the exhaust port 46 communicates with a combustion chamber 49 through the exhaust valve opening.

The intake and

exhaust valves

38i, 38e are normally urged by the valve springs 34 to move upwardly so that their valve heads close the intake and exhaust valve openings 47, 48, respectively. As shown in fig. 2, when the rod ends of the intake valve 38i and the exhaust valve 38e are depressed by the intake rocker arm 39i and the exhaust rocker arm 39e, which are held in abutment with the intake cam 36i and the exhaust cam 36e on the camshaft 36 and caused to oscillate, respectively, the intake valve 38i and the exhaust valve 38e are axially moved to open the intake valve opening 47 and the exhaust valve opening 48 at predetermined timings, respectively, thereby bringing the intake port 45 and the exhaust port 46 into fluid communication with the combustion chamber 49 to introduce an air-fuel mixture into the combustion chamber 49 and to discharge combustion gas from the combustion chamber 49 at predetermined timings.

According to the present embodiment, as shown in fig. 2, a throttle body 9 made of metal is fastened to an upstream end of an intake pipe 7, the intake pipe 7 being connected to an intake port 45 in a cylinder head 43.

The upstream end of the throttle body 9 is connected to an air cleaner 91 through a connecting pipe 90 made of a resin material. When the power unit 3 swings and vibrates, the intake pipe 7 tends to be subjected to upward, downward, leftward and rightward vibration loads, particularly upward, downward, leftward and rightward bending moments, including loads due to the weight of the throttle body 9 fastened to the intake pipe 7.

In view of these vibration loads, as shown in fig. 2, the intake pipe 7 includes upper and lower reinforcing

ribs

71 and 72 that stand on the upper and lower surfaces thereof, respectively, and extend in the direction in which intake air flows through the intake pipe 7.

As shown in fig. 3 and 4, the intake pipe 7 further includes left and right reinforcing

ribs

73 and 74 that stand on the left and right surfaces thereof, respectively, and extend in the direction in which intake air flows through the intake pipe 7.

As shown in fig. 2, the intake pipe 7 includes a cylinder head-side flange 75 on its downstream end serving as a joint point 7a connected to the inlet of the intake port 45 in the cylinder head 43 and a throttle body-side flange 76 on its upstream end serving as a joint point connected to the throttle body 9. It will be noted from fig. 6 to 8 that the intake pipe 7 is bent rearward from the cylinder head-side flange 75 toward the throttle body-side flange.

The internal combustion engine 4 incorporating the present embodiment further includes a fuel injection device 8 having an injector 81 in an upper portion of the intake pipe 7. The fuel injection device 8 injects fuel into the intake port 45.

As shown in fig. 3 and 4, the fuel injection device 8 includes: an ejector 81; an injector mounting base 80 through which the injector 81 is mounted on the intake pipe 7; and a control terminal 82 and a fuel connector 83, the control terminal 82 and the fuel connector 83 being mounted on the injector 81.

Fig. 5 is a sectional view of the cylinder head 43 and the cylinder head-side flange 75 of the intake pipe 7, including the axes x1 and x2 of the injector-

side mounting holes

84A and 84B, as seen along the line V-V in fig. 3.

In fig. 2 to 5, the fuel injection devices 8 are shown as dense dots, and the intake pipes 7 are shown as sparse dots, so that they can be easily visually distinguished from each other.

As shown in fig. 5, the injector 81 mounted on the intake pipe 7 by the injector mounting base 80 is fitted and inserted into the injector insertion hole 77, which injector insertion hole 77 is defined in the cylinder head-side flange 75 between the right rib 74 and the upper rib 71 of the intake pipe 7. The injector 81 is fastened to the intake pipe 7 by

bolts

78A and 78B, which

bolts

78A and 78B are inserted into and through injection

side mounting holes

84A and 84B, respectively, which injection

side mounting holes

84A and 84B are defined in a leftward extension of the injector mounting base 80. The bolt 78A is screwed into an intake pipe side fastening hole 79A, which intake pipe side fastening hole 79A is defined between the upper rib 71 and the left rib 73 in the cylinder head side flange 75 of the intake pipe 7. The bolt 78B is inserted through an intake pipe side fastening hole 79B, which intake pipe side fastening hole 79B is defined in the cylinder head side flange 75 between the upper rib 71 and the left rib 73 of the intake pipe 7.

The intake pipe side fastening hole 79A is an internally threaded hole. The injector mount base 80 is fastened to the intake pipe 7 by bolts 78A, which bolts 78A are inserted in the injection-side mounting holes 84A and screwed into the intake-pipe-side fastening holes 79A.

The intake pipe side fastening hole 79B is a through hole that doubles as: through which the inlet pipe 7 is fastened to the cylinder head 43. The bolt 78B inserted through the injection-side mounting hole 84B is inserted through the intake pipe-side fastening hole 79B and screwed into the intake pipe fixing female screw hole 43B defined in the cylinder head 43. The injector mount base 80 of the fuel injection device 8 and the intake pipe 7 are thus fastened together to the cylinder head 43 by the bolts 78B.

The intake pipe 7 is further fastened to the cylinder head 43 by a bolt 78C, which bolt 78C is inserted through an intake pipe-side fastening hole 79C (see fig. 7) defined in the cylinder head-side flange 75 and screwed into an internal threaded hole 43C defined in the cylinder head 43.

According to the present embodiment, the upper rib 71, the lower rib 72, the left rib 73, and the right rib 74 of the intake duct 7 increase the rigidity and the mechanical strength of the intake duct 7 against the vibration generated by the motorcycle 1 and the vibration generated in the intake duct 7, thereby increasing the vibration control capability of the intake duct 7. Since the injector 81 is provided at a position between the upper rib 71 and the right rib 74, even if the upper rib 71 is provided on the intake pipe 7, the injector 81 is positioned so as not to physically interfere with the upper rib 71 and the left and

right ribs

73, 74.

Since the injector-

side mounting holes

84A and 84B are provided between the upper rib 71 and the left rib 73, the injector 81 and the injector-

side mounting holes

84A and 84B are positioned on the left and right sides of the upper rib 71, respectively. Therefore, the ribs 71 to 74 for making the intake pipe 7 resist vibration from the motorcycle 1 are provided on the intake pipe 7 without physically interfering with the injector 81 and the injector-

side mounting holes

84A and 84B.

Alternatively, the ejector 81 may be positioned between the upper rib 71 and the left rib 73, with the ejector-

side mounting holes

84A and 84B positioned between the upper rib 71 and the right rib 74.

Fig. 6 is a vertical sectional view of the intake pipe 7 shown in fig. 2, wherein the intake pipe 7 is shown in the same orientation as in fig. 2.

Fig. 7 is a plan view of the intake duct 7 mounted on the motorcycle 1 as seen along the line VII-VII in fig. 6. Fig. 8 is a bottom view of the intake duct 7 mounted on the motorcycle 1 as seen along the line VIII-VIII in fig. 6.

The directions of the motorcycle 1 upward, forward, rightward and leftward are shown in fig. 6 to 8.

As shown in fig. 2, 6, and 7, the throttle body 9 is disposed upstream of the intake pipe 7, and the lower rib 72, the left rib 73, and the right rib 74 have rib heights h72, h73, and h74, respectively, which are gradually higher toward the downstream side in the direction in which air flows through the intake pipe 7.

Even when a load due to the weight of the throttle body 9 made of metal and its vibration is applied to the intake pipe 7 from the throttle body 9 connected to the upstream end of the intake pipe 7, since the rib height is gradually higher toward the downstream side where the load moment is high, the resistance and mechanical strength of the intake pipe 7 against the load moment increase toward the downstream side, allowing the intake pipe 7 to be stably supported on the internal combustion engine 4.

According to the present embodiment, since the injector 81 of the fuel injection device 8 and the injector-

side mounting holes

84A and 84B in the injector mounting base 80 are provided on both sides of the upper rib 71, the upper rib 71 has a relatively limited rib height h 71. However, the rib height h1 is gradually larger toward the downstream side in the direction of air flow through the intake pipe 7 as a whole, which contributes to increasing the resistance and mechanical strength of the intake pipe 7 against the load moment on the downstream side.

As shown in fig. 7, fastening holes 79C are formed in the cylinder head-side flange 75 for fastening the intake pipe 7 to the cylinder head 43. The bolt 78C is inserted through the fastening hole 79C, and is directly screwed into an internal threaded hole 43C defined in the cylinder head 43 without passing through an injector-side mounting hole, thereby fastening the intake pipe 7 to the cylinder head 43 (see fig. 5).

The effects obtained from the layout and shape of the ribs 71 to 74 on the intake pipe 7 and the layout of the injector 81 of the fuel injection device 8 and the injector-

side mounting holes

84A and 84B in the injector mounting base 80 are not limited to the internal combustion engine 4 for the swingable power unit 3 used on the scooter type motorcycle 1, the cylinder axis C of which is inclined forward to be almost horizontal.

The same effect is also applied to the following internal combustion engine: the cylinder axis of the internal combustion engine is slightly inclined forward from the vertical for use on a motorcycle (e.g., LMC) that includes a power unit fixedly mounted on a vehicle body frame.

In those alternative applications, the power unit is non-swingably mounted on the vehicle body frame. However, the effects obtained according to the above-described embodiment are also applicable because the saddle type vehicle itself is swingable and vibratable.

Specifically, the upper rib 71, the lower rib 72, the left rib 73, and the right rib 74 of the intake pipe 7 increase the rigidity and the mechanical strength of the intake pipe 7 against vibration generated by the vehicle and vibration generated in the intake pipe 7, thereby increasing the vibration controllability of the intake pipe 7. Since the injector 81 is provided at a position between the upper rib 71 and the right rib 74 or between the upper rib 71 and the left rib 73, the injector 81 is positioned so as not to physically interfere with the upper rib 71, the left rib 73, and the right rib 74 even if the upper rib 71 is provided on the intake pipe 7.

However, as exemplified in the above embodiment, the present invention is particularly useful when applied to the internal combustion engine 4 of the swingable power unit 3 on the scooter type motorcycle 1. In this case, the internal combustion engine 4 is included in the swingable power unit 3 mounted on the vehicle body frame 2 such that the internal combustion engine 4 can swing vertically together with the rear wheel 15, with the cylinder axis C oriented in the longitudinal direction of the motorcycle 1, and the intake pipe 7 bent and extending rearward from a joint point 7a between the intake pipe 7 and the cylinder head 43.

In the swingable power unit 3 in which the intake pipe 7 is bent and extends rearward from the junction point 7a between the intake pipe 7 and the cylinder head 43, even if the distance between the cylinder head 43 and the throttle body 9 is greater than a predetermined value for increasing the power output value of the internal combustion engine 4 in the low and medium rotation speed ranges, the upper rib 71, the lower rib 72, the left rib 73, and the right rib 74 of the intake pipe 7 effectively increase the rigidity and mechanical strength of the intake pipe 7 against vibrations generated by the motorcycle 1 and vibrations generated in the intake pipe 7, thereby increasing the vibration controllability of the intake pipe 7, and even if the upper rib 71 is provided on the intake pipe 7, the injector 81 is disposed so as not to physically interfere with the ribs 71 to 74.

As shown in fig. 8, the cylinder head-side flange 75 of the intake pipe 7 positioned downstream and connected to the cylinder head 43 has a larger connection area Sa than the connection area Sb of the throttle body-side flange 76 positioned upstream and connected to the throttle body 9.

Therefore, even if the throttle body 9 connected to the upstream end of the intake pipe 7 is relatively heavy, the intake pipe 7 is stably supported on the swingable power unit 3.

As shown in fig. 2, 6, and 7, the greater the curvature of the intake pipe 7, the greater the rib heights h71 and h72 of the upper rib 71 and the lower rib 72, except for the peripheral region 77a around the injector insertion hole 77 into which the injector 81 is inserted.

In other words, the swingable power unit 3 in which the intake pipe 7 is bent can provide the intake pipe 7 with higher vibration control capability by increasing the rib heights h71 and h72 according to the curvature of the intake pipe 7.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the illustrated embodiments, but various changes and modifications may be made in the embodiments within the scope of the present invention. For example, the power unit and the internal combustion engine according to the invention are not limited to the power unit and the internal combustion engine on a motorcycle, but are widely applicable to the power unit and the internal combustion engine on other kinds of saddle-type vehicles.

For purposes of illustration, the layout of various components in the leftward and rightward directions has been described in accordance with the illustrated embodiments. However, the components may be arranged according to opposite layouts in the left and right directions.

[ List of reference numerals ]

Motorcycle 2 vehicle body frame

3 power unit or swingable power unit 4 internal combustion engine

5 power transmission assembly 7 air inlet pipe

7a junction 8 fuel injection device

9 throttle body 15 rear wheel

22 main frame 22a lower frame

22b inclined part 22c horizontal part

23 power unit support bracket 24 connecting rod

30 power unit housing 30a crankcase

30L left half-shell 41 crankshaft

42 cylinder block 42a cylinder bore

43 cylinder head 43a combustion chamber upper limit surface

43B air inlet pipe fixing internal thread hole 45 air inlet

47 intake valve opening 49 combustion chamber

51-belt type continuously variable transmission 52 reducer gear mechanism

70 intake channel 71 upper rib

72 lower rib 73 left rib

74 Right rib 75 Cylinder head side flange

76 throttle body side flange 77 injector insertion hole

77a bolt inserted into the peripheral region 78A around the hole

78B bolt 78C bolt

79A intake pipe side fastening hole 79B intake pipe side fastening hole

79C intake pipe side fastening hole 80 injector mounting base

81 injector 82 control terminal

83 fuel connector 84A injector-side mounting hole

84B ejector side mounting hole 90 connecting pipe

91 air cleaner C Cylinder axis

h71 Rib height (of Upper Rib 71)

h72 Rib height (of lower Rib 72)

h73 Rib height (of left Rib 73)

h74 Rib height (of Right Rib 74)

Connection region of Sa cylinder head side flange 75

The connecting region of the Sb throttle body side flange 76.

Claims

1. An intake structure for an internal combustion engine used on a saddle type vehicle, the intake structure having an upper rib (71), a lower rib (72), a left rib (73), a right rib (74) erected on an upper surface, a lower surface, a left surface, a right surface, respectively, of an intake pipe (7) of the internal combustion engine (4), wherein:

an ejector (81) is provided between the upper rib (71) and one of the left rib (73) and the right rib (74), wherein:

injector-side mounting holes (84A, 84B) are provided between the other of the left rib (73) and the right rib (74) and the upper rib (71), and the injector (81) and the injector-side mounting holes (84A, 84B) are provided on the left and right sides of the upper rib (71), respectively.

2. The intake structure for an internal combustion engine used on a saddle type vehicle according to claim 1, wherein:

the internal combustion engine (4) is included in a swingable power unit (3), the swingable power unit (3) being mounted on a vehicle body frame (2) so as to swing together with a rear wheel (15), wherein a cylinder axis (C) of the internal combustion engine (4) is oriented in a longitudinal direction of the vehicle; and is

The intake pipe (7) is curved and extends rearward of the vehicle from a junction (7a) between the intake pipe (7) and a cylinder head (43) of the internal combustion engine (4).

3. The intake structure of an internal combustion engine for use on a saddle-type vehicle according to claim 1 or 2, wherein:

the throttle body (9) is arranged at the upstream of the air inlet pipe (7); and is

At least the lower rib (72), the left rib (73), and the right rib (74) have respective rib heights (h72, h73, h74) that are gradually larger toward the downstream side in the direction in which air flows through the intake duct (7).

4. The intake structure for an internal combustion engine used on a saddle type vehicle according to claim 3, wherein:

the intake pipe (7) has a downstream portion that is connected to a cylinder head (43) and has a connection area (Sa) that is larger than a connection area (Sb) of the intake pipe that is connected to an upstream portion of the throttle body (9).

5. The intake structure for an internal combustion engine used on a saddle type vehicle according to claim 4, wherein:

the upper rib (71) and the lower rib (72) have respective rib heights (h71, h72) such that the greater the curvature of the intake pipe (7), the greater the rib heights (h71, h72) except for a peripheral region (77a) around an insertion hole into which the injector (81) is inserted.