JP2905470B1 - Engine intake system - Google Patents

Abstract

The present invention provides an intake device for an engine, in which a duct can be reduced in weight and an output of the engine can be prevented from being reduced due to a step of an inner diameter of a connection portion between the duct and a carburetor. An air cleaner is attached to a carburetor via a holder. Vaporizer 1 for intake air from air cleaner
By screwing the duct 14 to be introduced into the holder 11 to the holder 11, the duct 14 can be easily fixed to the holder 11 even if a highly rigid resin duct 14 is adopted. The downstream end of the duct 14 is fitted to the upstream end of the bore 20 forming the intake passage of the carburetor 1. As a result, when the resin duct 14 having high rigidity is adopted, a step is less likely to be generated on an inner diameter surface at a connection portion between the duct 14 and the carburetor 1.
It is possible to prevent the output of the engine from decreasing due to the step.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake device connected to a carburetor of a motorcycle engine, for example.

[0002]

2. Description of the Related Art Conventionally, as an intake device of this type, as shown in FIG. 3, an air cleaner 40 is attached to a carburetor 42 via a holder 41, and intake air A from the air cleaner 40 is introduced into the carburetor 42. There is a rubber duct 43 which is supported by fitting its outer peripheral portion to the holder 41 (for example, Utility Model Registration No. 2544).
646). A lower case 40A constituting the lower half of the air cleaner 40 is fastened and fixed to the holder 41 by a plurality of bolts 44, and the holder 41 is fastened and fixed to an upper end surface of the vaporizer 42 by a plurality of bolts 45. A duct 4 is provided between the holder 41 and the vaporizer 42.
The seal 3 is sealed by fitting a rubber seal ring (O-ring) 48 into an annular groove 47 provided in the vaporizer 42 so as to surround the vaporizer 3.

[0003]

However, in the above-mentioned conventional example, since the duct 43 is made of rubber, it is necessary to secure the rigidity as a thick wall, and the weight of the duct 43 increases accordingly. In addition, in the rubber duct 43, it is difficult to increase the dimensional accuracy of the inner diameter at the connection portion with the vaporizer 42, and
Since it is easily deformed, there is a case where a large step P in the radial direction occurs at the inner diameter of the connection portion and the intake resistance increases, in which case the output of the engine is reduced. Further, when the seal ring 48 between the holder 41 and the carburetor 42 comes into contact with gasoline, for example, when the intake device is disassembled immediately after the engine is stopped,
It expands and cannot be fitted again in the annular groove 47.

A rubber duct 43 formed by a holder 41 is provided.
In order to ensure the support of the holder 41, the fitting length L of the peripheral edge of the fitting hole of the holder 41 to be fitted into the fitting groove 43a of the outer peripheral portion of the duct 43 must be secured to some extent. As a result, a thick portion is formed, which increases the weight of the holder 41 and increases rigidity. As a result, in the intake device of the multi-cylinder engine, when the holder 41 is warped, when the holder 41 is connected to the plurality of carburetors 42, the carburetor 42 is deformed so as to match the holder 41, and The positional relationship of the carburetors 42 may change, and this may affect the intake tuning between the carburetors.

The present invention solves such a problem and makes it possible to reduce the weight of the duct. This is because the output of the engine is reduced due to a step inside the connecting portion between the duct and the carburetor, and the holder is connected to the carburetor. It is an object of the present invention to provide an intake device for an engine that can also prevent poor synchronization of a carburetor.

[0006]

According to a first aspect of the present invention, there is provided an intake device for an engine, wherein an air cleaner is attached to a carburetor via a holder, and intake air from the air cleaner is introduced into the carburetor. duct, said
Inserted into the duct insertion hole formed in the holder and screwed
Is fixed to the holder by order, downstream end of the duct is fitted spigot on the upstream end of the bore forming the intake passage of the carburetor.

According to this structure, since the duct is fixed to the holder by screwing, the duct can be easily fixed to the holder even if a highly rigid resin or aluminum duct is employed. The duct can be made thinner and lighter. Also, since the downstream end of the duct is fitted to the upstream end of the bore of the vaporizer, if a highly rigid resin or aluminum duct is used, the duct molding accuracy will be reduced. Since it is better than the case of rubber, the step of the inner diameter at the connection between the duct and the carburetor can be reduced, and a decrease in the output of the engine due to the step at the connection can be prevented. Further, since the duct is fixed to the holder by screwing, it is not necessary to fit the outer peripheral portion of the duct to the peripheral portion of the fitting hole of the holder and hold it. It is not necessary to form the part thick. Therefore, since the rigidity of the holder can be reduced accordingly, even when the holder is warped, the holder is deformed and adapted to the vaporizer when the holder is mounted on a plurality of arranged vaporizers, and the deformation of the vaporizer is reduced. Therefore, there is no influence on mutual tuning of the vaporizers.

[0008] The intake system for an engine according to claim 2 is
In Claim 1, the said duct and the said holder are screwed by the screw body common to the said vaporizer. According to this configuration, since the fixing of the duct to the holder and the fixing of the holder to the vaporizer can be performed by a common screw body,
The number of parts can be reduced accordingly, and the fixing work is also facilitated.

According to a third aspect of the present invention, in the engine intake device according to the first or second aspect, the holder is provided with a circumferential groove that surrounds the duct and is provided with an annular connection protrusion provided on the carburetor. Is formed, and a sealing member that presses against the distal end of the connection protrusion is fitted into the circumferential groove. According to this configuration, the sealing member inserted into the circumferential groove on the holder side is pressed into contact with the tip of the connection protrusion on the carburetor side inserted into the circumferential groove, whereby the connection between the holder and the carburetor is formed. Since the airtightness is achieved, for example, even if the intake device is disassembled immediately after the engine stops, even if the seal member comes into contact with gasoline, the seal member does not come off the circumferential groove due to swelling, and subsequent assembly work Becomes easier. Also,
Since the circumferential groove for inserting the seal member is formed on the holder side, the rigidity of the holder can be further reduced. Further, since the connection protrusion is inserted into the circumferential groove, the positioning between the holder and the carburetor is facilitated.

[0010]

Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a partially broken side view showing an intake device for an engine according to an embodiment of the present invention. This intake device is an intake device for a four-cylinder engine of a motorcycle, and four carburetors 1 are provided, one for each cylinder. Air cleaner 2
Is composed of an air cleaner main body 3 and a cleaner element 4. The air cleaner body 3 is made of a resin such as polypropylene, and includes a lower case 3A and an upper case 3B.

An intake chamber 5 is formed in front of the inside of the lower case 3A so as to face below the cleaner element 4.
A cleaner outlet 6 is formed at the inside rear of A. The intake chamber 5 communicates with a cleaner inlet 7 at the front F.
A suction duct (not shown) is connected to the cleaner inlet 7, and outside air indicated by an arrow A is introduced through the suction duct. A purified air chamber 8 is formed inside the upper case 3B and faces above the cleaner element 4. The purified air chamber 8 communicates with the cleaner outlet 6 of the lower case 3A. The cleaner element 4 is made of an air-permeable foam material. The lower case 3A and the upper case 3B are connected to each other by a plurality of bolts (not shown) while holding the cleaner element 4 therebetween. Breather pipe 9 communicating from the rear R to the purified air chamber 8 of the air cleaner body 3
Is for introducing blow-by gas from the crankcase into the purified air chamber 8.

[0012] portion after the lower case 3A as the cleaner outlet 6 of the air cleaner main body 3, the holder 11 by bolts 10
To be fixed. As shown in the plan view of FIG. 2 (A), the holder 11 has a nut 1 with which the bolt 10 is screwed.
2 are buried in two places. The holder 11 has four duct insertion holes 13 arranged in the length direction (left-right direction).
A resin duct 14 for introducing the intake air from the air cleaner 2 shown in FIG. 1 into the carburetor 1 is inserted into each of the duct insertion holes 13. Further, a peripheral groove 16 into which a connection projection 15 provided on a peripheral edge of the cleaner outlet 6 in the lower case 3A is inserted is formed on an outer peripheral portion of an upper surface of the holder 11, and the connection groove 1 is formed in the peripheral groove 16.
A sealing member 17 made of urethane resin or the like shown in FIG.

The lower surface of the holder 11 is shown in FIG.
As shown in FIG.
A seal member 19 made of urethane resin or the like is fitted in and bonded to the circumferential groove 18. On the other hand, an annular connection protrusion 21 is formed on the upper end surface of each carburetor 1 on the outer peripheral side of the bore portion 20 constituting the intake passage.
8, and the tip of the connection projection 21 is pressed against the seal member 19, so that the holder 11 and each vaporizer 1 are pressed.
The airtightness of the connection part with this is achieved.

Each of the ducts 14 is integrally formed with two mounting pieces 22 projecting outward from the outer diameter portion thereof and engaging with the upper surface of the holder 11, respectively. Vaporizer 1 by screw 23
It is screwed to the upper end face of.

The downstream end of the duct 14 is fitted to the upstream end of the bore 20 forming the intake passage of the carburetor 1 by means of a centering fitting. That is, at the downstream end of the duct 14, as shown in an enlarged view in FIG. 2C, an outer diameter small portion 24 whose outer diameter is slightly smaller than the upper side thereof is formed, and the vaporizer 1 is formed. Bore section 2
0, an inner diameter large portion 25 whose inner diameter is slightly larger than its lower side is formed, and the outer small diameter portion 24 of the duct 14 is placed inside the inner large diameter portion 25 of the vaporizer 1. By fitting, the duct 14 and the bore 20 are connected in a state where they are aligned. Contrary to the above case, the duct 14 may be provided with a large inside diameter portion, and the bore portion 20 of the carburetor 1 may be provided with a small outside diameter portion, so that both are fitted to each other.

As shown in FIG. 2A, bolts (not shown) for fastening the lower case 3A and the upper case 3B of the air cleaner main body 3 together with the holder 11 are provided at three places on the outer periphery of the holder 11. A nut 26 to be screwed is embedded.

In the above configuration, since the duct 14 shown in FIG. 2C is fixed to the holder 11 by the screw 23,
Even if the resin duct 14 having high rigidity is employed as described above, the resin duct 14 can be easily fixed to the holder 11, and the duct 14 can be made thinner and lighter. Further, since the downstream end of the duct 14 is fitted to the upstream end of the bore 20 of the carburetor 1, if the resin duct 14 having high rigidity is employed as described above, the molding of the duct 14 is performed. Since the accuracy is improved as compared with the conventional rubber, the step P in the radial direction of the inner diameter surface at the connection portion between the duct 14 and the carburetor 1 can be reduced, and as a result, the engine caused by the step at the connection portion Output can be prevented from decreasing.

[0018] In addition, the duct 14 by screws Hol
Because it is fixed to the da 11, does not need to be held by fitting the outer peripheral portion of the duct 14 to the peripheral portion of the duct the insertion hole 13 of the holder 11, need to form the periphery of the duct the insertion hole 13 in the thick And the rigidity of the holder 11 can be reduced accordingly. Therefore, even if the holder 11 is warped,
When the air cleaner 2 is attached to a plurality of carburetors 1 arranged in series, the holder 11 is deformed and adapted to the carburetor 1, so that the deformation of the carburetor 1 can be suppressed, and the carburetors are synchronized with each other due to the deformation. Will not be affected.

Further, the sealing member 19 inserted into the circumferential groove 18 on the holder 11 is pressed against the tip of the connection projection 21 on the carburetor 1 side to maintain the airtightness of the connection between the holder 11 and the carburetor 1. Therefore, for example, even if the intake device is disassembled immediately after the engine is stopped and the seal member 19 comes into contact with gasoline, the seal member 19 does not come off the circumferential groove 18 due to swelling. Becomes easier.

The circumferential groove 1 into which the sealing member 19 is inserted
Since 8 is formed on the holder 11 side, the rigidity of the holder 11 can be further reduced. Moreover, the connection protrusion 21 is formed in the circumferential groove 18.
Is inserted, the positioning of the holder 11 and the carburetor 1 is facilitated, and displacement between the two 11 and 1 hardly occurs. Furthermore, since the fixing of the duct 14 to the holder 11 and the fixing of the holder 11 to the vaporizer 1 are performed by the common screw 23, the fixing member can be omitted accordingly, and the number of parts can be reduced.

Although the duct 14 is made of resin in the above embodiment, it may be made of light metal such as aluminum.

[0022]

As described above, according to the intake system for an engine of the present invention, even if a duct made of a rigid resin or aluminum is used, it can be easily fixed to the holder. The duct can be made thinner and lighter.
In addition, by improving the molding accuracy of the duct, the step of the inner diameter at the connection between the duct and the vaporizer can be reduced,
It is possible to prevent the output of the engine from decreasing due to the step at the connection portion. Furthermore, since it is not necessary to form the peripheral portion of the duct insertion hole in the holder with a large thickness, the rigidity of the holder can be reduced accordingly, so that when attaching the holder to a plurality of vaporizers, the vaporizer may be deformed due to deformation of the vaporizer. It does not affect mutual tuning.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a main part of an intake device for an engine according to an embodiment of the present invention.

2A is a plan view showing a holder portion of the intake device, FIG. 2B is a cross-sectional view taken along line II of FIG. 2A, and FIG.
FIG. 4 is an enlarged cross-sectional view showing a portion C of FIG.

FIG. 3 is a sectional view of a main part showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vaporizer, 2 ... Air cleaner, 11 ... Holder, 14 ...
Duct, 18 ... Circumferential groove, 19 ... Seal member, 20 ... Bore part, 21 ... Connection protrusion, 23 ... Screw (screw body)

Claims (3)

(57) [Claims] An air cleaner is attached to a carburetor via a holder, and a duct for introducing intake air from the air cleaner to the carburetor is inserted into a duct insertion hole formed in the holder.
An intake device for the engine, wherein the downstream end of the duct is fixed to the holder by screwing , and the downstream end of the duct is fitted to the upstream end of a bore forming an intake passage of the carburetor. 2. The intake system for an engine according to claim 1, wherein the duct and the holder are screwed by a screw body common to the carburetor. 3. The holder according to claim 1, wherein the holder has a circumferential groove surrounding the duct and into which an annular connection protrusion provided on the carburetor is inserted. An intake device for an engine in which a seal member that is in pressure contact with a tip portion of a connection protrusion is fitted.