MOTORCYCLE POWER TRANSMISSION UNIT The present invention relates to a power transmission unit for a motorcycle designed to supply the outside air in a unitary housing of the power transmission unit, thereby cooling the power transmission unit. Traditionally, a power transmission unit is known for a motorcycle designed in such a way that the unit case of the power transmission unit is rotatably mounted to a body frame and the unit case has an opening for supplying the external air in the unit case, cooling the power transmission unit thereby (see patent document 1, for example). Japanese Patent No. 3064389 (Figure 2). With reference to Figure 2 of the patent document 1, a unitary oscillating type motor 11 is rotatably mounted to a body frame 10 and a filter hose 77 is connected to a transmission case 12 which constitutes a part of the unit swing type motor 11. The filter hose 77 extends obliquely upwardly from the transmission case 12 towards the rear end of the vehicle, and a cooling air filter 70 is connected to the upper end (rear end) of the hose 77. The cooling air filter 70 is connected to the upper end of the filter hose 77. The cooling air filter 70 is fixed to a rear fender 23. With this structure, the outside air is introduced from the filter of cooling air 70 and is supplied through the filter hose 77 to the transmission case 12, thereby cooling the inside of the transmission case 12. However, the filter hose 7 7 extends rearwardly of the vehicle body and the rear end of the filter hose 77 is placed on top of a rear wheel 13. Consequently, there is the possibility that foreign matter such as dust is generated around the rear wheel 13 enters the filter hose 77 from the rear end of the filter. To solve this problem, the cooling air filter 70 must be equipped to prevent the entry of foreign matter into the filter hose 77 in the patent document 1, causing an increase in the cost of production for the vehicle. It is therefore an object of the present invention to provide a power transmission unit for a motorcycle that can suppress the entry of foreign matter and can reduce the cost. According to the invention as defined in claim 1, there is provided a power transmission unit for a motorcycle designed such that a power transmission unit unit box is rotatably mounted to a body frame for transmitting power therethrough from an engine to a rear wheel, and the unit case has an opening for connecting an outside air introduction tube to supply the outside air through the outside air introduction tube in the case of the unit, thereby cooling the power transmission unit, wherein the body frame is provided with a frame member placed substantially directly above the opening of the unit case; and the outer air introduction tube has a fixed upper end portion to the frame member. According to the invention as defined in claim 2, the frame member is provided through a step support element for supporting a passenger step. According to the invention according to the claim
3, an intake element is fixed to the step support member and the upper end portion of the outside air introduction tube is fixedly fitted to the entry element. According to the invention according to the claim
4, a cover element for covering an upper opening of the outdoor air introduction tube is provided in the vicinity of the upper end portion of the outdoor air introduction tube. According to the invention according to claim 5, the step support element is placed substantially directly above the opening of the unit case, and the outer air introduction tube has a substantially L-shaped structure. According to the invention according to claim 1 , the upper end portion of the outer air introduction tube is fixed to the frame member located substantially directly above the opening of the unit case. Accordingly, by placing the frame member separate from the rear wheel, the upper end portion of the outer air introduction tube can be positioned separately from the rear wheel. As a result, the entry of foreign matter such as the dust that is generated around the rear wheel in the outer air introduction tube can be suppressed, and no air filter is required in the upper end portion of the air introduction tube outside, thus reducing a production cost for the motorcycle. As mentioned above, the frame member is placed substantially directly above the opening of the unit case, and the upper end portion of the outer air introduction tube is fixed to the frame member. For this reason, the outer air introduction tube can be reduced in size, thus reducing a cost for the external air introduction tube. According to the invention according to the claim
2, the step support element is also used as the frame element. In other words, the step of the passenger is supported by the step supporting element and the upper end portion of the outer air introduction tube is also supported by the step supporting element. Thus, the step support member also serves as the frame member according to claim 2. Accordingly, as compared to the case where the step support member and the frame member are supplied as separate elements. , the number of parts can be reduced. According to the invention as defined in claim 3, the upper end portion of the outer air introduction tube is fixedly adapted to the fixed input element to the step support element. Accordingly, the upper end portion of the outdoor air introduction tube that oscillates with the power transmission unit can be reliably supported.
According to the invention as defined in claim 4, the cover member is positioned in the vicinity of the upper end portion of the outer air introduction tube. Consequently, the entry of foreign matter such as dust into the outer air introduction tube can be suppressed. According to the invention as defined in claim 5, the outer air introduction tube has a substantially L-shaped structure. Therefore, the foreign matter that entered the outside air introduction tube can be stopped in a part bent in the L-shape of this tube, thus avoiding the entry of foreign matter into the unit's box. A preferred embodiment of the present invention will now be described with reference to the appended drawings. In the drawings, the arrows that are shown through "FRONT" (FRONT), "REAR" (REAR), "RIGHT" (RIGHT), "LEFT" (LEFT), "UPPER" (UPPER) and "LO ER" "(BOTTOM) indicate the directions of agreement as seen by the operator and the orientation of each drawing is equal to that of the reference numbers that are included in them. Figure 1 is a partially cross-sectional side view of a motorcycle 10 adopting the power transmission unit according to the present invention. As shown in Figure 1, the motorcycle 10 includes a body frame 11, an articulated mechanism 14 having a pivot shaft 12 and a power unit 15 rotatably mounted through the articulated mechanism 14 to a rear portion. of the body frame 11. The power unit 15 is composed of a motor 16 and a power transmission unit 17 equipped in the rear part of the engine 16. The power transmission unit 17 is composed of a unit case 18 and a transmission mechanism that is not shown. The housing of the unit 18 is rotatably mounted to the body frame 11 to transmit power therethrough from the engine 16 to a rear wheel 19. The body frame 11 is composed of a main pipe 21 equipped in the front end, a main frame connected to the main tube 21 and extending obliquely downward therefrom, a cross frame 23 connected to the rear ends of the main frame 22 so as to extend in the lateral direction of the motorcycle 10 and a pair of right and left rear frames 24R and 24L (only the rear left frame 24L appears) which extends obliquely upwards from the cross frame 23 towards the rear end to constitute a rear portion of the body frame 11. A front fork 25 is installed with control capability to the main tube 21. A front wheel 28 is installed with the lower ends of the front orifice 25 and a steering handle 29 is installed at the end upper of the front cleat 25. The rear wheel 19 is mounted on the rear end of the power unit 15 which also serves as a rear swing arm. A rear shock absorber unit 26 is connected between the rear end of the power unit 15 and the rear frame 24L. The reference number 27 india a shock absorber support. The articulated mechanism 14 is interposed between the power unit 15 and the cross frame 23 and has a support shaft 31 in the vicinity of the cross frame 23. An articulated element 32 extends rearwardly from the support shaft 31 and the Pivot shaft 12 is equipped at the rear end of the articulated element 32. The housing of the unit 18 has a front portion 18a formed with an opening 33 for introducing the outside air and an air introduction tube 34 connects to the opening 33. from the box in unit 18. That way, the case of the unit 18 has the opening 33, and the outer air introduction tube 34 is connected to the opening 33, thus supplying the outside air in the case of the unit 18 through the external air introduction tube 34 for cooling the power transmission unit 17. The motor 16 constituting a front portion of the power unit 15 has a cylinder block 36 and a collecting unit 37 and an exhaust unit 38 are connected to the cylinder block 36 of the engine 16. The collecting unit 37 is composed of a primary air filter 41, a fuel supply device 42 connected to the primary air filter 41 and an intake pipe 43 connected to the fuel supply device 42 to supply a mixture of air fuel to the engine 16. Struts (not shown) project down from the left and right rear frames 24R and 24L, and the primary air filter 41 is installed to the struts of the frames rear 24R and 24L. The exhaust unit 38 is composed of an exhaust pipe 45 connected to the engine 16 so as to extend backwards and a muffle 46 connected to the exhaust pipe 45 so as to extend backwards. A secondary air supply device 50 is installed to the exhaust pipe 45 as part of the exhaust unit 38 to supply secondary air to the exhaust pipe 45, thereby cleaning the exhaust gases from the exhaust unit 38. The number reference 51 indicates a secondary air conduit for connecting the exhaust unit 38 and the secondary air supply device 50 and the reference number 52 indicates a control tube for connecting the intake pipe 43 and the air supply device secondary 50. A luggage box 53 is provided on the upper side of the rear frames 24R and 24L and a fuel tank 54 is provided on the rear side of the luggage case 53. A double seat 55 is installed with rotational capability on the upper side of the luggage box 53 and the fuel tank 54 so that the double seat 55 can be opened to expose the luggage box 53 and the fuel tank 54. Although not ap As shown, a fuel tube is provided for connecting the fuel tank 54 and the engine 56. The reference character "He" indicates a helmet stored in the luggage box 53. The motorcycle 10 further includes a passenger step 57, support 58, handrail 59, front brake unit 61, front fender 62, a hood element 63, rear fender 64 and secondary air supply tube 67. Figure 2 is an enlarged view of an essential part of the motorcycle equipped with a transmission unit according to the present invention. As shown in Figure 2, the power transmission unit 17 has the box of the unit 18 and the box of the unit 18 has the opening 33 for introducing the outside air into the power transmission unit 17. The tube of introduction of outside air 34 connects the opening 33 to introduce the outside air through the opening 33 in the housing of the unit 18. The outdoor air introduction tube 34 has a rear end portion 34b, which is fixedly connected to the opening 33 formed in the front portion 18a of the housing of the unit 18. The outer air introduction tube 34 further has an upper end portion 34a, which is fixedly connected to a step supporting element 72 as an element of frame 71 extending downward from the rear frame 24L. The step support element 72 is installed in an upper end portion thereof to the rear frame 24L and extends obliquely downwardly from the rear frame 24L. The passenger step 57 is installed in a lower end portion 72b of the step support element 72. The step support element also serves as an element for securing the upper end portion 34a of the outer air introduction tube 34. The step support member 72 is comprised of a main arm 74 that extends obliquely downward from the rear frame 24L and an auxiliary arm 75 extending from the frame rear 24L to the main arm 74 and is connected to a lower portion 74c of the main arm 74 to reform the main arm 74. The passenger step 57 is fixed to a lower end portion 74b of the main arm 74. A cover element 81 is supplied in the vicinity of the upper end portion 34a of the outer air introduction tube 34 so as to cover an upper opening 82 of the outer air introduction tube 34. More specifically, two strut elements 83 and 84 project from the auxiliary arm 75 and the cover element 81 is fixed to the auxiliary arm 75 through the strut elements 83 and 84 by means of the screws 85. The air introduction tube outer 34 is a tubular element that is substantially L-shaped, which is composed of upper end portion 34a having a flange 86, a vertically extending bellows portion 87, a bent portion 88 extending from the lower end of the bellows portion 87 and which is bent horizontally rearwardly and the rear end portion 34b connected to the rear end of the bent portion 88. Thus, the upper end portion 34a communicates with the rear end portion 34b through of the bellows portion 87 and the bent portion 88. The positional relationship between the opening 33 of the housing of the unit 18 and the step support element 72 is determined so that the element Step support 72 as frame member 71 is placed substantially directly above the opening 33 of the housing of unit 18. Reference numerals 91 and 92 indicate hose strips and reference numbers 93 indicate fastening bolts. for fixing the step support element 72 to the rear frame 24L. The step support member 72 also serves as the frame member 71 for supporting the upper end portion 34a of the outer air introduction tube 34. In other words, the step support element 72 serves both as an element for supporting the step of passenger 57 also as an element for supporting the upper end portion 34a of the outer air introduction tube 34. Thus, the step support member 72 also serves as the frame member 71 in this preferred embodiment. Accordingly, in comparison with the case that the step support member 72 and the frame member 71 are supplied as separate elements, the number of parts can be reduced. Although the step support member 72 for supporting the passenger step 57 is used as the frame member 71 in this preferred embodiment, any other element placed substantially directly above the opening 33 of the case of the unit 18 is can be used as an element for fixing the upper end portion 34a of the outer air introduction tube 34. The cover element 81 is placed in the vicinity of the upper end portion 34a of the outer air introduction tube 34 so that the entry of foreign matter such as dust into the outdoor air introduction tube 34 can be avoided. The step support element 72 is placed substantially directly above the opening 33, and the outer air introduction tube 34 has a substantially L-shaped structure. Due to the substantially shaped structure
L of the outside air introduction tube 34 foreign matter that has entered the outside air introduction tube 34 is stopped in the L-shaped bent portion 88 of the tube 34, thus preventing the entry of foreign matter into the case of the unit 18. Figure 3 is a cross-section taken along line 3-3 of Figure 2. As shown in Figure 3, an intake element 94 is installed through the L-shaped support 95 step support member 72, and the upper end portion 34a of the outer air introduction tube 34 is adapted to a lower portion of the intake element 94, thereby securing the outer air introduction tube 34 through the intake element 94 to the step support element 72. In this way, the intake member 94 is fixed to the step support member 72, and the upper end portion 34 of the outside air introduction tube 34 is fixed to the intake element 94. . After adapting the upper end portion 34a of the outer air introduction tube 34 to the intake member 94, the outer circumference of the upper end portion 34a is clamped through the hose band 91. Accordingly, the upper end portion 34a of the outer air introduction tube 34 that oscillates together with the power transmission unit 17 can be reliably fixed to the intake member 94. In addition, the bellows portion 87 of the air introduction tube External 34 can contract and expand at the time of application of an external force. Accordingly, the oscillation of the outdoor air introduction tube 34 transmitted from the power transmission unit (notation 17 of Figure 1) can be absorbed by the bellows portion 87 of the outdoor air introduction tube 34.
The intake element 94 has an upper opening 94a which is inclined approximately 45 ° with respect to the axis of the intake member 94 and which is laterally oriented towards the inside of the motorcycle. Furthermore, the cover element 81 is provided so as to cover the upper opening 94a of the intake element 94. The upper opening 94a of the intake element 94 is located in the vicinity of the passenger step (notation 57 of Figure 2) which is locate in a position where it is hardly splashed with mud or similar. In addition, the upper opening 94a is covered with cover element 81. Accordingly, the entry of foreign matter such as dust into the outer air introduction tube 34 can be suppressed, and it is not necessary to provide in particular an air filter or similar to clean the outside air to be introduced into the outdoor air introduction tube 34. Figure 4 is a schematic perspective view of an outside air introduction portion including the outside air introduction tube in accordance with the present invention. As shown in Figure 4, the intake member 94 is mounted to the main arm 74 of the step support member 72 and the strut members 83 and 84 for assembling the cover member 81 project from the auxiliary arm 75 of the element. of step support 72 in the forward and laterally inward directions of the motorcycle, respectively. The strut elements 83 and 84 have holes 83h and 84h, respectively, and the cover element 81 has two screw mounting portions 81v and 84v respectively adapted to be in line with the holes 83h and 84h of the strut elements 83 and 84. Accordingly, the cover element 81 is fixed to the strut elements 83 and 84 by inserting the screws 85 through the holes 83h and 84h and screwing the screws 85 into the threaded mounting portions 81v and 84v, respectively. The step support element 72 is a relatively small element that is adapted to be installed in the rear frame 24L. In consecuense, even when it is necessary to perform additional work to fix the upper end portion 34a of the outer air introduction tube 34 to the step support element 72, the step support element 72 can be easily assembled, disassembled, operated and operated. More specifically, the structure for fixing the upper end portion 34a of the outer air introduction tube 34 to the step support member 72 is only a structure for mounting the intake element 94 and the two strut elements 83 and 84 to the step support element 72, so that an increase in costs can be avoided by fixing the outer air introduction tube 34. The operation of the power transmission unit as mentioned above will be described below. Referring again to Figure 2, the upper end portion 34a of the outer air introduction tube 34 is attached to the step support member 72 as the frame member 71 placed substantially directly above the opening 33. In addition , the step support element 72 is located separately from the rear wheel (annotation 19 of Figure 1). Therefore, the upper end portion 34a of the outer air introduction tube 34 can be positioned separately from the rear wheel 19. As a result, the entry of foreign matter as dust that is generated around the rear wheel 19 in the tube The external air introduction 34 can be suppressed and no air filter is required in the upper end portion 34a, thus reducing the production cost for the motorcycle. As mentioned above, the step suppression element is located substantially directly above the opening 33, and the upper end portion 34a of the outdoor air introduction tube 34 is fixed to the step support element 72. Therefore both, the outer air introduction tube 34 can be reduced in size, also reducing a cost for the outdoor air introduction tube. In addition, the upper end portion 34a has an air inlet portion is located at a relatively high level, so that it is possible to provide a structure that suppresses the entry of water into the housing of the unit 18. Furthermore, in accordance with the structure of the present invention, no opening is formed in the frame of the body 11, so that there is no possibility of reduction in the rigidity of the body frame 11. In claim 1, the frame member for fixing the portion The upper end of the outer air introduction tube is provided as a separate element from the step support element. In other words, the frame member and the step support element can be separate elements. In claim 2, the upper end portion of the outer air introduction tube can be fixed directly to the step support element. In claims 1 to 3, the cover element is not provided, that is, it is not an essential element. In claims 2 to 4, the shape of the outer air introduction tube is not limited, although various forms such as the L shape, the J shape and the I shape can be adopted. The present invention is conveniently applicable to a power transmission unit for a motorcycle. Figure 1 is a partially transverse side view of a motorcycle adopting the power transmission unit according to the present invention. Figure 2 is an enlarged view of an essential part of the motorcycle according to the present invention. Figure 3 is a cross-section taken along line 3-3 of Figure 2. Figure 4 is a schematic perspective view of an outside air introduction portion for the power transmission unit according to the present invention. 10: Motorcycle 11: body frame 16: engine 17: power transmission unit 18: unit case 19: rear wheel 33: aperture 34: outside air intake tube 34a: upper end portion of the air intake tube exterior 57: passenger step 71: frame element 72: step support element 81: cover element 82: upper opening of the outside air intake tube 94: intake element