ITTO20000073A1 - BIKE WITH INTERNAL COMBUSTION ENGINE. - Google Patents

Description

DESCRIPTION of the industrial invention entitled: "Bicycle with internal combustion engine"

DESCRIPTION

The present invention refers to a bicycle with an internal combustion engine, and in particular to a muffler.

A bicycle with an internal combustion engine disposed under a body frame is disclosed in Japanese Publicly Available Patent No. Hei 8-108.875. This bicycle will be described with reference to Figure 7. The bicycle comprises a V-shaped body frame composed of a main frame 02 extending from a head tube 01 and a saddle post 03, and an internal combustion engine 04 arranged under the body frame.

A fuel tank 05 is mounted in the V-shaped folded portion formed by the main frame 02 and the saddle post 03, and a storage basket 07 extending further in the vertical direction is disposed between the saddle post 03 and a rear wheel 06 positioned behind the seat post 03.

A muffler 08 is disposed between the internal combustion engine 04 and the rear wheel 06. An exhaust pipe 09 connected to an exhaust port of the internal combustion engine 04 extends backwards substantially in the horizontal direction passing through a space under the internal combustion engine 04, and is connected to muffler 08.

The bicycle with an internal combustion engine, which is substantially in the shape of a bicycle and is narrow in the direction of its width, must contain respective components within the reduced width in order to maintain an aerodynamic appearance of the bicycle. To satisfy this requirement, the muffler 08 is arranged in the space between the internal combustion engine 04 and the rear wheel 06; however, in this case, since the muffler 08 is located close to the internal combustion engine 04, the length of the exhaust pipe 09 may become too short to ensure a desirable exhaust efficiency.

In light of the preceding situation, the present invention has been realized, and an object of the present invention is to make a bicycle with an internal combustion engine of the type in which a muffler is arranged between the internal combustion engine and a rear wheel, which is capable of making the length of an exhaust pipe sufficient to ensure desirable exhaust efficiency.

To achieve the preceding object, according to the invention described in claim 1, a bicycle with an internal combustion engine is made, comprising pedals operated with human energy, an approximately V-shaped body frame composed of a main frame and a saddle post, and an internal combustion engine disposed under the body frame, wherein the bicycle comprises: a muffler disposed between the internal combustion engine and a rear wheel; wherein an exhaust pipe extending from an exhaust port of the internal combustion engine is longitudinally curved under the internal combustion engine and is thus connected to the muffler.

Since the exhaust pipe is longitudinally curved under the internal combustion engine and is connected to the muffler located between the internal combustion engine and the rear wheel, it is possible to ensure that the length of the exhaust pipe is sufficient to ensure an efficiency of desirable discharge.

According to the invention described in claim 2, in addition to the configuration of the invention described in claim 1, the curved portion of the exhaust pipe is arranged within a lateral distance between the pedals.

Since the exhaust pipe is disposed within a lateral distance between the pedals, it does not interfere with the pedals, and since the exhaust pipe does not protrude laterally from the vehicle body, it does not impede the aerodynamic appearance of the bicycle.

According to the invention described in claim 3, in addition to the configuration of the invention described in claim 1 or 2, the muffler is formed by integrating two parts with each other by arranging a separating plate between them, and the pipe exhaust pipe and an outlet pipe are arranged in one of the two parts forming the muffler.

Since the exhaust pipe and the outlet pipe are arranged only in one part of the muffler and are not arranged in the other part of the muffler, the muffler can be assembled easily.

According to the invention described in claim 4, in addition to the configuration of the invention described in claim 3, the muffler is formed by integrating an upper part with a lower part in the vertical direction with the insertion of the separating plate between them.

With this configuration, it is possible to increase the degree of freedom in determining the position in the direction of the vehicle body width in which the exhaust pipe is inserted into the muffler, and consequently facilitate the design of the exhaust pipe.

The invention is described with reference to the attached drawings, in which:

Figure 1 represents a side view showing the overall configuration of a bicycle with an internal combustion engine in accordance with an embodiment of the present invention;

Figure 2 is a side view of an air filter and its vicinity;

Figure 3 is a sectional view along the line III-III of Figure 2;

Figure 4 is a sectional view along the line IV-IV of Figure 2;

figure 5 is a top view of an exhaust pipe of a muffler, with parts partially interrupted;

figure 6 represents a sectional view along the line VI-VI of figure 5; And

Figure 7 represents a side view of a bicycle with an internal combustion engine according to the prior art.

In the following, an embodiment of the present invention will be described with reference to Figures 1 to 6.

Figure 1 represents a side view of the overall configuration of a bicycle 1 with an internal combustion engine according to this embodiment.

A body frame 2 is composed of a main tube 4 extending backwards and slightly obliquely downwards from a head tube 3 and a saddle post 5 extending upwards and slightly rearwards from a rear portion of the main tube 4. Such a body frame is made in an approximately V shape in a side view.

The lower end of the saddle post 5 extends slightly downward from the connecting portion at which the saddle post 5 is connected to the main tube 4. A pair of left and right rear supports 6 extend rearward and obliquely downward from the lower end 4 of the saddle post 5, are bent in the horizontal direction, and extend backward in the horizontal direction. Another pair of left and right rear supports 7 extend rearward and obliquely downward from an upper portion of the saddle post 5. The rear ends of the rear supports 6 and 7 are connected to a wheel support portion 8 rear.

A rear wheel 9 is rotatably supported by the rear wheel support portion 8, and the upper side of the rear wheel 9 is covered with a rear mudguard 10.

A stand 19 is mounted in an oscillating manner on the support portion 8 of the rear wheel.

A front wheel 12 is rotatably supported at the forked lower ends of a front fork 11 rotatably supported by the head tube 3. A handlebar 14 is mounted at the upper end of the front fork 11.

The upper side of the front wheel 12 is covered by the front mudguard 13.

A fuel tank 15 is arranged astride the main tube 4 and extends from the connecting portion at which the main tube 4 is connected to the head tube 3 to the central portion of the main tube 4. A saddle 16 is mounted on the upper end of the saddle post 5.

A small-sized single-cylinder four-stroke internal combustion engine 20 hangs downward from frame 2 of the V-shaped body.

A bracket 17 is fixed to the connecting portion at which the main tube 4 is connected to the upright of the saddle 5 so as to be suspended downwards from this portion. A front side attachment bracket mounted on the upper portion of a crankcase 20a of the internal combustion engine 20 is supported by the lower end of the bracket 17 through a support pin 17a. A rear side attachment bracket mounted on the internal combustion engine 20 is supported, through a support pin 18a, by brackets 18 projecting from the front portions of the rear supports 6.

The internal combustion engine 20 is configured so that a cylinder 20b is directed obliquely upward and forward from the crankcase 20a and a drive gear box 21 is integrally disposed with a rear portion of the crankcase 20a.

A pedal gear shaft 22 and a chain drive wheel 23 are arranged, through a one-way clutch, on an output shaft 21a protruding left and right from the drive gear box 21, and a chain 25 is suspended between the drive wheel for chain 23 and a driven wheel for chain 24 arranged on the support portion 8 of the rear wheel.

Cranks 26 are mounted on the right and left ends of the pedal shaft 22, and pedals 27 are rotatably supported by the outer ends of the cranks 26.

Accordingly, when the chain drive wheel 23 is rotated by the internal combustion engine drive 20 through the drive gears, the rear wheel 9 can be rotated through the chain 25, thereby causing the bicycle to move forward, and when the pedals 27 are operated with human energy, the rear wheel 9 is also rotated through the chain 25, thus causing the bicycle to move forward.

An air filter 30 and a battery 31 are contained in a common housing 32 which is disposed in a space between the saddle post 5 and the rear wheel 9 disposed behind the saddle post 5.

The enclosure 32 is divided vertically into a flattened upper box configured as an air filter enclosure 32a, and a flattened lower box configured as a battery containment enclosure 32b. The casing 32 has, on its right side, a common rectangular opening which is closed by a covering member 33. The covering member 33 is fixed to the casing 32 by means of two screws 34.

With reference to Figure 2, the casing 32 is made in a rectangular shape in a side view and is inserted in a rectangular space with its front and rear sides surrounded by the saddle post 5 and the rear wheel 9 and with its sides upper and lower surrounded by rear supports 6 and 7.

Attachments 32c and 32d protrude from the front surface and rear surface of the casing 32. The front side attachment 32c is screwed onto a bracket 5a protruding from the saddle post 5 by means of a screw / nut assembly 35 (figure 3) and the The rear side attachment 32d is screwed onto a bracket 6a protruding from the rear support 6 on the lower side by means of a screw / nut assembly 36 (see figure 4). The casing 32 is thus mounted on the frame 2 of the body.

As illustrated in Figures 3 and 4, the air filter 30 is configured by integrating the air filter housing 32a with the cover member 33, with an air filter filter element 30a inserted between them. The interior of the air filter 30 is divided by the filter element 30a of the air filter into a dirty right side 30b and a clean left side 30c.

The saddle post 5 extends vertically along the axis of the front surface of the air cleaner 30. An air intake duct 37 on the right side and a connecting tube 38 on the left side extend forward from the front surface of the filter. 30, with the upright of the saddle 5 arranged between them.

The air intake duct 37 on the right side of the saddle post 5 is inserted into the dirty side 30b through the cover member 33, and the connecting tube 38 on the left side of the saddle post 5 is inserted into the clean side 30c through the air filter housing 32a.

The connecting tube 38 extending forward from the left side of the front surface of the air cleaner housing 32a is bent downwards along the left side surface of the saddle post 5, is again bent forward, and extends along the left side surface of the bracket 17. A connecting portion 38a at the forward end of the connecting pipe 38 is connected to the carburetor 40 disposed above the crankcase 20a.

The connecting tube 38 is arranged between the right side of the left side crank arm 26 and the bracket 17.

An air intake duct 39 extending backward and obliquely upward from the slanted cylinder 20b is connected to the carburetor 40 positioned obliquely upwardly relative to the cylinder 20b.

The carburetor 40 is displaced slightly to the left from the central portion of the vehicle, and the connecting pipe 38 connected between the carburetor 40 and the air cleaner 30 is disposed along the left side surface of the seat post 5. Consequently, the pipe connecting pipe 38 extends in a straight line along the longitudinal direction, whereby the resistance to the suction of air in the connecting pipe 38 is reduced.

Since the air filter 30 and the battery 31 are arranged in the common casing 32 and the common opening of the casing 32 on the right side is covered by the cover member 33, it is possible to reduce the number of components and improve the assembly efficiency, and also to easily perform maintenance work, such as replacing the filter element 30a of the air filter or replacing the battery 31, by opening the cover member 33.

The battery 31 is inserted in the housing of the battery 32b from the right side of the vehicle body and is covered by the covering member 33, and therefore this battery 31 is not visible from the outside.

Since the heavy battery 31 is located under the air filter 30, it is possible to lower the center of gravity of the bicycle.

A muffler 50 is disposed in a downwardly extending space between the curved rear surface of the drive gear case 21 and the rear wheel 9.

The muffler 50 is suspended from the transmission gearbox 21 so that an attachment 56 erected on an upper casing 51 of the muffler 50 is screwed, by means of a screw / nut assembly 57, onto a bracket 21b projecting from the curved rear surface of the muffler. box 21 of transmission gears.

A loading tube 45 connected to a front exhaust port of the cylinder 20b extends backward and obliquely downward from the latter along the rear surface of the forward inclined cylinder 20b, is bent in the approximately horizontal direction under the crankcase 20a , and extends further back in the horizontal direction. The exhaust pipe 45 thus extending backwards forms a pair of longitudinal forward and return branches before the muffler 50, and is finally connected to the muffler 50.

The arrangement of the exhaust pipe 45 will be more fully described with reference to FIG. 5. The exhaust pipe 45 is composed of an inclined portion 45a (extending to the left side in FIG. 5) extending from the slightly offset exhaust port. right from the L-L 'axis of the vehicle body; a folded portion 45b which is folded in an approximately horizontal direction; a first rectilinear portion 45c extending backwards parallel to the L-L 'axis; a curved portion 45d which is curved to the left in a U shape before the muffler 50; a second rectilinear portion 45e extending forwardly from the curved portion 45d; a curved portion 45f which is curved again to the left in a U-shape in the same longitudinal position as the folded portion 45b; and a third rectilinear portion 45g extending backwards from the curved portion 45f so as to fit into the muffler 50.

The first, second, and third straight portions 45c, 45e and 45g of the exhaust pipe 45 are all disposed in the same horizontal plane along the rear surfaces of the crankcase 20a and drive gearbox 21, and the curved portions 45d and 45f of the exhaust pipe 45, each of which has a reduced lateral width, are positioned within the lateral width of the muffler 50 and are also arranged between the right and left pedal cranks 26.

As illustrated in FIGS. 5 and 6, the muffler 50 is made in a rectangular shape in a top view. The muffler 50 is configured by simultaneous welding of the upper casing 51 to a lower casing 52 with a separator 53 inserted between them. The interior of the muffler 50 is divided by the separator 53 into an upper space configured as a first expansion chamber 5a and a lower space configured as a second expansion chamber 52a.

The upper housing 51, which has the front surface shaped in a shape similar to that of the curved rear surface of the transmission gearbox 21 and also has the rear surface shaped in a shape similar to that of the rear wheel 9, is disposed between the transmission gear box 21 and the rear wheel 9.

The exhaust pipe 45 is inserted into the second expansion chamber 52a of the lower casing 52 of the muffler 50. A tubular extension portion 45h of the exhaust pipe 45 extends rearward into the second expansion chamber 52a, is curved into a shape U-shaped, and is supported by a support post 58. The tubular extension portion 45h thus supported extends slightly forward, and is bent upwardly through the separator 53. The upper end of the tubular extension portion 45h it is open towards the first expansion chamber 5a arranged above the separator 53.

A communication pipe 54 for communicating the first and second expansion chambers 51a and 52a with each other is provided to pass through the separator 53. An outlet pipe 55 for communicating the second chamber expansion 52a with the outside is arranged to pass through the rear wall of the lower casing 52.

The exhaust gas expelled by the internal combustion engine 20 passes through the exhaust pipe 45 having a sinuous longitudinal course to ensure a specific distance; enters the first expansion chamber 51a, passes from the first expansion chamber both to the second expansion chamber 52a through the communication pipe 54; and is discharged to the outside through the outlet pipe 55.

Since the muffler 50 is configured so that no components are provided in the upper casing 51 and the exhaust pipe 45 and the outlet pipe 55 are arranged in the lower casing 52, it is possible to simplify the assembly of the muffler 50, reduce the number of assembly jigs, and improve assembly functionality.

Since the upper casing 51 and the lower casing 52 are welded simultaneously to each other with the separator 53 inserted between them, it is possible to achieve the watertight seal of the muffler 50 with certainty.

Since the muffler 50 is composed of the upper and lower parts, i.e. the first and second expansion chambers Sla and 52a, it is possible to increase the degree of freedom in determining the position in the direction of the width of the vehicle body in which the exhaust pipe 45 fits into the muffler 50, and consequently facilitates the design of the exhaust pipe 45 with a sinuous longitudinal course.

The bicycle with an internal combustion engine in this embodiment, which is substantially in the shape of a bicycle and has a reduced width, must contain respective components within the reduced width in order to maintain an aerodynamic appearance of the bicycle.

To meet this requirement, the muffler 50 is not arranged laterally with respect to the rear wheel 9, but is arranged in the central position in the lateral (width) direction of the vehicle body by exploiting the space between the rear wheel 9 and the gearbox 21 of transmission arranged in front of the rear wheel 9. In this case, since the distance between the exhaust port of the cylinder 20b and the muffler 50 is shortened, the length of the exhaust pipe is also shortened. In this embodiment, however, since the exhaust pipe has a sinuous longitudinal course under the crankcase 20a and the transmission gear box 21, it is possible to ensure the necessary length of the exhaust pipe.

Furthermore, since the curved portions 45d and 45f of the sinuous exhaust pipe 45, each of which has a reduced lateral width, are positioned within a lateral distance between the pedals 27, i.e. they are disposed between the right and left pedal cranks 26, the exhaust 45 does not protrude laterally from the vehicle body and therefore does not compromise the aerodynamic aspect of the bicycle.

In this embodiment, the air filter 30 and the battery 31 are also arranged in the central position in the lateral (width) direction of the vehicle body by exploiting the dead space between the saddle post 5 and the rear wheel 9.

Since the air intake duct 37 and the connecting tube 38 extend from the air filter 30 disposed behind the saddle post 5 with the saddle post 5 inserted between them, they can be arranged within the specific width in the direction side without interference with the saddle post 5.

Claims (4)

CLAIMS 1. Bicycle with an internal combustion engine, comprising human-powered pedals, an approximately V-shaped body frame consisting of a main frame and a saddle post, and an internal combustion engine arranged under the body frame aforesaid, in which the aforesaid bicycle comprises: a muffler arranged between said internal combustion engine and a rear wheel; wherein an exhaust pipe extending from an exhaust port of said internal combustion engine is longitudinally curved back and forth under said internal combustion engine and is then connected to said muffler. 2. An internal combustion engine bicycle according to claim 1, wherein said curved portion of said exhaust pipe is disposed within a lateral distance between said pedals. 3. Bicycle with an internal combustion engine according to claim 1 or 2, in which the aforesaid muffler is made by integrating two parts with each other by arranging between them a separating plate, and the aforesaid exhaust pipe and an outlet pipe are arranged in one of the two aforesaid parts forming the aforesaid muffler. 4. Bicycle with an internal combustion engine according to claim 3, wherein the aforesaid muffler is made by integrating an upper part with a lower part in the vertical direction, arranging the aforementioned separating plate between them.