JP2013113115A - Air intake structure of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a reduction in service life due to the occurrence of cracks by reducing stress concentration in a connecting pipe while elastically connecting an air intake pipe, connected to an air intake port, and a throttle valve body to each other.SOLUTION: An air intake structure includes: a valve body 59 that houses a throttle valve 58 therein; an air intake pipe 31 that is connected to an air intake port 61 of an engine 8; an elastic connecting pipe 62 that has one end into which the valve body 59 is inserted and the other end into which the air intake pipe 31 is inserted, fluidically connects between the valve body 59 and the air intake pipe 31, and allows relative displacement between the valve body 59 and the air intake pipe 31; and a clamp band 63 that can be wound around the elastic connecting pipe 62 spaced across a gap 75 from the outer peripheral surface of an intermediate part 71 sandwiched between the one end of the elastic connecting pipe 62 and the other end of the elastic connecting pipe 62 before application of a clamping force load, and connects the valve body 59, the air intake pipe 31, and the elastic connecting pipe 62 by collectively clamping the one end of the elastic connecting pipe 62 and the other end of the elastic connecting pipe 62 after application of the clamping force load.

Description

  The present invention relates to an intake structure for an engine.

  An engine intake structure comprising an intake pipe connected to an intake port of an engine, a carburetor having a throttle valve that adjusts an intake flow rate, and a connection pipe that fluidly relays between the intake pipe and the carburetor is known. Yes.

JP 2011-202544 A

  In a conventional engine intake structure, a rubber connecting pipe may be applied to insulate the carburetor from engine vibration. This rubber connection pipe allows relative displacement between the intake pipe and the carburetor.

  The intake pipe, carburetor and rubber connection pipe are connected by inserting the intake pipe into one end of the connection pipe, inserting the valve body of the carburetor into the other end of the connection pipe, and tightening the connection pipe with a clamp band. To do.

  By the way, the intake pipe, the carburetor, and the rubber connection pipe may have a structure of being connected by a so-called spigot joint. The joint includes a socket at each end of a rubber connection pipe, and an intake pipe side insertion part and a carburetor side insertion part that fit into the socket. The inner peripheral surface of the socket and the outer peripheral surface of the insertion portion are provided with irregularities that fit together to prevent the joint from coming off.

  The connecting pipe relays between the socket on the carburetor side and the socket on the intake pipe side, and has an inner peripheral surface that becomes a part of the wall surface of the intake passage. The inner peripheral surface is a surface that connects the inner peripheral surface of the carburetor and the inner peripheral surface of the intake pipe with substantially the same diameter, and is smaller in diameter than the socket portion. That is, the connecting pipe has an internal structure in which a socket portion at each end and a portion that is sandwiched between the socket portions and serves as a part of the intake passage are connected stepwise.

  In the conventional intake structure of an engine, the connecting pipe is tightened with a clamp band, so that the connecting pipe receives a tightening force in the direction of reducing the diameter. This tightening force concentrates as a high initial stress on the stepped part on the inner surface of the connecting pipe, and overlaps with the stress generated by the displacement of the upstream side (carburetor side) and downstream side (intake pipe side) of the connecting pipe. There was a possibility of cracking the tube.

  In addition, the clamping band tightening force also reduces the diameter of the portion that bears a part of the intake passage, which may affect the cross-sectional area of the intake passage in this portion.

  On the other hand, the joint on the intake pipe side and the joint on the carburetor side may be tightened with separate clamp bands. There was a possibility of becoming.

  Therefore, the present invention provides an elastic connection between the intake pipe connected to the intake port and the valve body that houses the throttle valve, and it is easy to adjust the support rigidity as appropriate, reducing stress concentration in the connection pipe and generating cracks. An object of the present invention is to provide an intake structure for an engine that is unlikely to cause a decrease in life due to the above.

  In order to solve the above-described problems, an intake structure for an engine according to the present invention includes a valve body that houses a throttle valve that adjusts an intake flow rate, an intake pipe that is connected to an intake port of the engine, and one end into which the valve body is inserted. And an elastic member that fluidly relays between the valve body and the intake pipe and allows relative displacement between the valve body and the intake pipe. Before the tightening force is loaded, the connecting pipe can be wound around the connecting pipe with a gap from the outer peripheral surface of the intermediate part of the connecting pipe sandwiched between the one end and the other end. And a clamp band for fastening the valve body, the intake pipe and the connecting pipe by collectively tightening the one end and the other end after the applied load.

  According to the present invention, while the intake pipe connected to the intake port and the valve body housing the throttle valve are elastically connected, the support rigidity can be adjusted appropriately, and the stress concentration in the connection pipe is eased to generate cracks. Therefore, it is possible to provide an intake structure for an engine that is unlikely to cause a decrease in life due to the above.

1 is a left side view showing a motorcycle to which an intake structure for an engine according to an embodiment of the present invention is applied. The perspective view which shows the engine intake structure which concerns on embodiment of this invention from diagonally upward right. The right view which shows the intake system of the engine which concerns on embodiment of this invention. The left view which shows the intake system of the engine which concerns on embodiment of this invention. The top view which shows the intake system of the engine which concerns on embodiment of this invention. The perspective view which shows the intake structure of the engine which concerns on embodiment of this invention from diagonally left front. Sectional drawing which shows the intake structure of the engine which concerns on embodiment of this invention. 1 is an enlarged sectional view showing an intake structure of an engine according to an embodiment of the present invention. Sectional drawing which shows the other example of the intake structure of the engine which concerns on embodiment of this invention.

  An embodiment of an intake structure for an engine according to the present invention will be described with reference to FIGS.

  FIG. 1 is a left side view showing a motorcycle to which an engine intake structure according to an embodiment of the present invention is applied.

  In the present embodiment, front and rear, top and bottom, and left and right expressions are based on a rider who rides the motorcycle 1 and is a user of the motorcycle 1.

  As shown in FIG. 1, the motorcycle 1 according to this embodiment is a scooter type vehicle. The motorcycle 1 includes a so-called underbone-type body frame 2, a front wheel 5 positioned in front of the body frame 2, and a steering that can swing in the left-right direction with respect to the body frame 2 and rotatably supports the front wheel 5. The mechanism 6, the rear wheel 7 located behind the body frame 2, and can swing in the vertical direction with respect to the body frame 2, rotatably support the rear wheel 7, and the engine 8 and the transmission device 9 are integrated. A power unit 11, a vehicle body cover 12 that covers the vehicle body frame 2, and a seat 13 on which a rider sits.

  The vehicle body frame 2 is a plurality of steel hollow tubes combined together, and is connected to a head pipe 14 located at the front upper portion, a down tube 15 connected to the head pipe 14, and a rear end portion of the down tube 15. A cross member 16 and a pair of left and right seat rails 17 connected to the vicinity of the left and right ends of the cross member 16 are provided.

  The head pipe 14 supports the steering mechanism 6 so as to be steerable in the left-right direction of the vehicle. The down tube 15 bends in an L-letter shape in a side view and extends rearward while extending obliquely rearward and downward from a front upper end connected to the head pipe 14. The cross member 16 extends from the central portion connected to the down tube 15 in the left and right directions of the vehicle. The left and right seat rails 17 extend rearward and upward from the front lower end connected to the cross member 16, and include a front half portion having a large slope and a rear half portion having a small slope.

  The steering mechanism 6 is connected to a pair of left and right front forks 18 that have a suspension mechanism (not shown) and rotatably support the front wheels 5, a front fender 20 that covers the front wheels 5, and a top portion of the front forks 18. And a pair of left and right handles 21. The rider can turn the motorcycle 1 by steering the handle 21 left and right. A handle 21 on the right side of the vehicle is an accelerator grip.

  The power unit 11 also serves as a swing arm that rotatably supports the rear wheel 7 and supports the rear wheel 7 so as to be swingable in the vertical direction. The power unit 11 is connected to the cross member 16 via the link member 22. The link member 22 supports the power unit 11 so as to be swingable around the pivot shaft 23. The rear cushion unit 25 hangs between the power unit 11 and the vehicle body frame 2 and buffers the force transmitted from the rear wheel 7 to the vehicle body frame 2.

  The engine 8 is a small displacement of 50 cc class or 125 cc class, for example, a four-cycle internal combustion engine, and directs the center line of a cylinder (not shown) in the front-rear direction of the motorcycle 1.

  The intake system 26 of the engine 8 is located above the power unit 11 and is connected to the engine 8 via an air cleaner 27, an outlet pipe 28, a carburetor 29, and an intake pipe 31 in order from the upstream side. The intake system 26 supplies an air-fuel mixture (fuel / air mixture) to the engine 8.

  The rear wheel 7 obtains driving force from the engine 8 via the transmission device 9.

  The vehicle body cover 12 includes a handle cover 33 made of synthetic resin, a front leg shield 35, a footboard 36, a frame center cover 37, a frame side cover 38 and a frame lower cover 39, which are connected to each other to cover and hide the vehicle body frame 2. The design surface of the motorcycle 1 is formed to adjust the appearance.

  The front leg shield 35 faces the seat 13 at the rear of the vehicle, blocks the traveling wind and protects the rider's legs.

  The footboard 36 is a large cover connected to the front leg shield 35, the frame center cover 37, and the frame lower cover 39, and includes a footrest portion 41 on which a rider straddling the seat 13 bends a knee and places a foot.

  The frame side cover 38 has a pair of left and right sides and covers the respective side surfaces below the seat 13.

  The frame lower cover 39 covers the lower part of the foot board 36.

  The seat 13 includes a front half portion 13a where a rider sits by bending a knee while keeping his feet and knees aligned with the footrest portion 41, and a rear half portion 13b where a passenger sits.

  Further, the seat 13 covers the upper portion of the storage box 42 and the fuel tank 43 and is connected to the frame side cover 38.

  The rear fender 45 extends rearward from the lower side of the fuel tank 43 and covers the upper side of the rear wheel 7.

  Next, the intake structure of the engine will be described in detail.

  FIG. 2 is a perspective view showing the intake structure of the engine according to the embodiment of the present invention from diagonally upward to the right.

  FIG. 3 is a right side view showing the intake system of the engine according to the embodiment of the present invention.

  FIG. 4 is a left side view showing the intake system of the engine according to the embodiment of the present invention.

  FIG. 5 is a plan view showing an intake system of the engine according to the embodiment of the present invention.

  As shown in FIGS. 2 to 5, the engine 8 according to the present embodiment includes a cylinder assembly 46 that is positioned on the front side and tilts the cylinder shaft forward substantially horizontally, and a crankcase 47 that is positioned on the rear side. .

  The cylinder assembly 46 includes a cylinder block 48 coupled to the crankcase 47, a cylinder head 49 coupled to the cylinder block 48, and a head cover 51 coupled to the cylinder head 49. The cylinder block 48, the cylinder head 49, and the head cover 51 It overlaps sequentially in the order of. A synthetic resin engine cover 52 covers the cylinder block 48 and the cylinder head 49.

  The crankcase 47 includes a pair of left and right frame support portions 53 that are connected to the link member 22 of the vehicle body frame 2. The frame support portion 53 extends forward from the lower surface of the crankcase 47. The frame support portion 53 has a swing center hole 55 through which the pivot shaft 23 is inserted. The swing center hole 55 is located at the front end portion of the frame support portion 53.

  The conduction device 9 is integrally provided on the left side of the crankcase 47 and extends rearward.

  The intake system 26 is located above the cylinder assembly 46 and the crankcase 47 and is connected to the cylinder head 49.

  The air cleaner 27 filters dust and the like in the air and supplies clean air as intake air to the carburetor 29.

  The outlet pipe 28 guides the intake air that has passed through the air cleaner 27 and has been cleaned to the carburetor 29.

  The carburetor 29 guides the fuel from the fuel tank 43 and mixes it with the intake air flowing from the air cleaner 27 in the form of a mist.

  FIG. 6 is a perspective view showing the intake structure of the engine according to the embodiment of the present invention from the diagonally left front.

  FIG. 7 is a cross-sectional view showing the intake structure of the engine according to the embodiment of the present invention.

  FIG. 8 is an enlarged cross-sectional view showing the intake structure of the engine according to the embodiment of the present invention in a region A of FIG.

  As shown in FIGS. 6 to 8 in addition to FIGS. 2 to 5, the intake structure 57 of the engine 8 according to this embodiment includes a valve body 59 that houses a throttle valve 58 that adjusts the intake flow rate, An intake pipe 31 connected to the intake port 61, an elastic connection pipe 62, and a clamp band 63 that connects the valve body 59, the intake pipe 31 and the connection pipe 62 are provided.

  The valve body 59 is a part of the intake passage, and is also a container that houses the throttle valve 58. The valve body 59 includes a venturi portion connected to the fuel tank 43. The venturi section increases the flow velocity of the intake air and simultaneously lowers the pressure to atomize the fuel. The valve body 59 includes an insertion portion 65 connected to the connection pipe 62.

  The throttle valve 58 is a butterfly valve that opens and closes an intake passage in the valve body 59. The throttle valve 58 includes a valve shaft 58a that crosses the intake flow path, and a disc-shaped valve body 58b that has the valve shaft 58a as a rotation center axis.

  The intake pipe 31 supplies the intake air that has passed through the carburetor 29 and becomes an air-fuel mixture to the intake port 61 of the cylinder head 49. The intake pipe 31 is a curved elbow pipe. The intake pipe 31 includes an insertion portion 66 connected to the connection pipe 62.

  The connecting pipe 62 is a rubber pipe. The connection pipe 62 has one end portion into which the valve body 59 is inserted and the other end portion into which the intake pipe 31 is inserted, and fluidly relays between the valve body 59 and the intake pipe 31. The relative displacement with the intake pipe 31 is permitted.

  Further, the connecting pipe 62 relays between the socket 67 on the valve body 59 side, the socket 68 on the intake pipe 31 side, and the sockets 67, 68 to form an inner peripheral surface 69 that becomes a part of the wall surface of the intake passage. And having an intermediate portion 71. The inner peripheral surface 69 is a surface that connects the inner peripheral surface of the valve body 59 and the inner peripheral surface of the intake pipe 31, and has a smaller diameter than the sockets 67 and 68. That is, the connecting pipe 62 has an inner portion where sockets 67 and 68 at the respective ends and a portion (intermediate portion 71) sandwiched between the sockets 67 and 68 and serving as a part of the intake passage are connected in a stepped manner. It has a structure.

  The inner diameter of the intake passage is such that the inner diameter of the valve body 59 <the inner diameter of the inner peripheral surface 69 <the inner diameter of the intake pipe 31 so that the diameter gradually increases from the upstream side toward the downstream side. There is no blocking or blocking.

  The socket 67 and the insertion portion 65, and the socket 68 and the insertion portion 66 are so-called spigot joints 72 and 73. The inner peripheral surfaces of the sockets 67 and 68 and the outer peripheral surfaces of the insertion portions 65 and 66 are provided with irregularities that are fitted to each other and serve to prevent the joint from coming off. The spigot joints 72 and 73 connect the valve body 59, the intake pipe 31 and the connection pipe 62.

  The clamp band 63 can be wound around the connection pipe 62 with a gap 75 from the outer peripheral surface of the intermediate part 71 sandwiched between one end of the connection pipe 62 and the other end of the connection pipe 62 before the clamping force is loaded. Yes, after loading with a tightening force, one end of the connecting pipe 62 and the other end of the connecting pipe 62 are tightened together. In the clamp band 63, a belt portion 63a slightly shorter than the outer peripheral length of the connection pipe 62 is wound around the connection pipe 62, and bolts 76 are passed through flanges 63b located at respective end portions of the belt section 63a to tighten nuts 77, thereby connecting the connection pipe. Tighten 62.

  Further, the connecting pipe 62 has a concave portion 78 (first concave portion) that becomes a gap 75 on the outer peripheral surface of the intermediate portion 71. The recess 78 goes around the connecting pipe 62. The width Q of the gap 75 (that is, the width Q of the recess 78) is wider than the width P of the intermediate portion 71.

  The intake structure 57 of the engine 8 according to the present embodiment having such a configuration fastens the clamp band 63 and deforms the connecting pipe 62 to fix the spigot joints 72 and 73. Since the connecting pipe 62 has a lower elastic modulus than the clamp band 63, the intake pipe 31 and the valve body 59 (is easily deformed), the socket 67 firmly holds the insertion portion 65 by tightening the clamp band 63, and the socket 68. Holds the insertion portion 66 firmly.

  On the other hand, the intermediate portion 71 of the connecting pipe 62 is less susceptible to the tightening force due to the gap 75 separating the clamp band 63. Specifically, when the gap 75 is secured even after the clamping of the clamp band 63 is completed, the intermediate portion 71 is hardly deformed, and the deformation in the radial direction is suppressed to be particularly small. Further, even when the gap 75 is filled in the tightening process of the clamp band 63 and the clamp band 63 is in contact with the bottom of the recess 78, the deformation of the intermediate portion 71 is suppressed as compared with the case without the gap 75 from the beginning. The effect of suppressing the deformation of the intermediate portion 71 is further improved by making the width Q of the gap 75 wider than the width P of the intermediate portion 71, and the initial stress generated in the step portion between the sockets 67, 68 and the intermediate portion 71 is reduced. It will also ease.

  Due to the deformation suppressing effect of the intermediate portion 71, the inner peripheral surface 69 of the intermediate portion 71 can easily maintain the initial shape, and the relationship between the inner peripheral surface of the valve body 59 and the inner peripheral surface of the intake pipe 31 can be easily maintained. This prevents deformation of the aspect in which the inner peripheral surface 69 of the connection pipe 62 protrudes into the intake passage after the clamp band 63 is tightened, and prevents an increase in pressure loss in the intake passage. Further, if a deformation in a mode in which the inner peripheral surface 69 of the connection pipe 62 protrudes into the intake passage occurs, the fuel temporarily stays due to the turbulence of the flow, and the accumulated fuel is irregularly mixed with the intake air. However, the idling structure 57 of the engine 8 according to the present embodiment can also suppress the occurrence of such an event.

  Further, by suppressing the initial deformation amount of the intermediate portion 71, the connecting pipe 62 can further attenuate the vibration transmitted from the engine 8 to the valve body 59 (carburetor 29).

  As described above, according to the intake structure 57 of the engine 8 according to the present embodiment, the intermediate portion 71 of the connection pipe 62 is prevented from being directly clamped by the clamp band 63, and between the intake pipe 31 and the valve body 59. It is possible to bridge the clamp band 63 on. Since the clamp band 63 supports the valve body 59 together with the connecting pipe 62, for example, the support rigidity of the valve body 59 can be appropriately adjusted by changing the plate thickness of the belt portion 63a of the clamp band 63.

  Next, another embodiment of the intake structure 57 of the engine 8 according to this embodiment will be described. A description common to the intake structure 57 of the engine 8 is omitted.

  FIG. 9 is a cross-sectional view showing another example of the intake structure for the engine according to the embodiment of the present invention.

  As shown in FIG. 9, the intake structure 57 </ b> A of the engine 8 according to the present embodiment includes a clamp band 63 </ b> A instead of the clamp band 63. The clamp band 63 </ b> A has a recess 81 (second recess) that becomes the gap 75.

  On the other hand, the connecting pipe 62A does not require the recess 78 in the connecting pipe 62 and has a substantially uniform cylindrical outer peripheral surface.

  In the case of the intake structure 57A of the engine 8 according to the present embodiment, the intermediate portion 71 of the connecting pipe 62A is less susceptible to the tightening force due to the gap 75 separating the clamp band 63A. Specifically, when the gap 75 is secured even after the clamping of the clamp band 63A is completed, the intermediate portion 71 is hardly deformed, and the deformation in the radial direction is suppressed to a small value. Further, even when the gap 75 is filled in the clamping process of the clamp band 63A and the connecting pipe 62A is in contact with the bottom of the recess 81, the deformation of the intermediate portion 71 is suppressed as compared with the case without the gap 75 from the beginning. The effect of suppressing the deformation of the intermediate portion 71 is further improved by making the width Q of the gap 75 (that is, the width Q of the concave portion 81) wider than the width P of the intermediate portion 71, and the sockets 67, 68 and the intermediate portion 71 This also relieves the initial stress generated in the step portion.

  Due to the deformation suppressing effect of the intermediate portion 71, the inner peripheral surface 69 of the intermediate portion 71 can easily maintain the initial shape, and the relationship between the inner peripheral surface of the valve body 59 and the inner peripheral surface of the intake pipe 31 can be easily maintained. This prevents deformation of the aspect in which the inner peripheral surface 69 of the connecting pipe 62A protrudes into the intake passage after the clamp band 63A is tightened, and prevents an increase in pressure loss in the intake passage. Further, if a deformation in a mode in which the inner peripheral surface 69 of the connecting pipe 62A protrudes into the intake passage occurs, the fuel temporarily stays in the turbulent flow, and the accumulated fuel is irregularly mixed with the intake air. However, the intake structure 57A of the engine 8 according to this embodiment can also suppress the occurrence of such an event.

  Further, by suppressing the initial deformation amount of the intermediate portion 71, the connecting pipe 62A can further attenuate the vibration transmitted from the engine 8 to the valve body 59 (carburetor 29) side.

  As described above, according to the intake structure 57A of the engine 8 according to the present embodiment, the intermediate portion 71 of the connection pipe 62A is prevented from being directly clamped by the clamp band 63A, and between the intake pipe 31 and the valve body 59. The clamp band 63A can be bridged over the Since the clamp band 63A supports the valve body 59 together with the connecting pipe 62A, the support rigidity of the valve body 59 can be appropriately adjusted by changing the plate thickness of the belt portion 63a of the clamp band 63A, for example.

  The connection pipe 62 may be tightened by applying a clamp band 63A to the intake structure 57 of the engine 8. In this case, the same effects as the intake structures 57 and 57A are obtained.

  The intake structure 57, 57A of the engine 8 is not limited to the carburetor 29, but is applied to an intake structure of an engine provided with an injector (not shown) in the intake pipe 31 and provided with a throttle body instead of the carburetor 29. You can also.

  Therefore, according to the intake structures 57 and 57A of the engine 8 according to the present embodiment, the intake pipe 31 connected to the intake port 61 and the valve body 59 containing the throttle valve 58 are elastically connected and the support rigidity is increased. It is easy to adjust appropriately, and the stress concentration of the connecting pipe 62 is relaxed, and it is difficult for the life to be reduced due to the occurrence of cracks.

DESCRIPTION OF SYMBOLS 1 Motorcycle 2 Body frame 5 Front wheel 6 Steering mechanism 7 Rear wheel 8 Engine 9 Transmission apparatus 11 Power unit 12 Car body cover 13 Seat 13a Front half part 13b Rear part 14 Head pipe 15 Down tube 16 Cross member 17 Seat rail 18 Front fork 20 Front fender 21 Handle 22 Link member 23 Pivot shaft 25 Rear cushion unit 26 Intake system 27 Air cleaner 28 Outlet pipe 29 Carburetor 31 Intake pipe 33 Handle cover 35 Front leg shield 36 Footboard 37 Frame center cover 38 Frame side cover 39 Frame lower cover 41 Footrest part 42 Storage Box 43 Fuel Tank 45 Rear Fender 46 Cylinder Assembly 47 Crankcase 48 Cylinder Block 49 Linda head 51 Head cover 52 Engine cover 53 Frame support part 55 Swing center hole 57, 57A Intake structure 58 Throttle valve 58a Valve shaft 58b Valve body 59 Valve body 61 Intake port 62, 62A Connection pipe 63, 63A Clamp band 63a Belt part 63b Flange 65, 66 Insertion part 67, 68 Socket 69 Inner peripheral surface 71 Intermediate part 72, 73 Spigot joint 75 Clearance 76 Bolt 77 Nut 78, 81 Recess

Claims (4)

A valve body that houses a throttle valve that adjusts the intake flow rate;
An intake pipe connected to the intake port of the engine;
One end portion into which the valve body is inserted and the other end portion into which the intake pipe is inserted to fluidly relay between the valve body and the intake pipe, and between the valve body and the intake pipe An elastic connecting tube allowing relative displacement;
Before the tightening force is loaded, the one end and the other end can be wound around the connecting tube with a gap from the outer peripheral surface of the intermediate portion of the connecting tube, and after the tightening force is loaded, An intake structure for an engine, comprising: a clamp band that collectively tightens one end and the other end to connect the valve body, the intake pipe, and the connection pipe. The engine intake structure according to claim 1, wherein a width of the gap is wider than a width of the intermediate portion. 3. The engine intake structure according to claim 1, wherein the connection pipe has a first concave portion serving as the gap on an outer peripheral surface of the intermediate portion. The engine intake structure according to any one of claims 1 to 3, wherein the clamp band includes a second recess serving as the gap.

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