Title of Invention

"AN ENGINE SUPPORTING STRUCTURE FOR A MOTOR BICYCLE"

Abstract

An engine supporting structure for a motor bicycle having a main frame (5) extending rearward from a head pipe (3); an engine disposed under said main frame (5); and an engine hanger (7) for supporting said engine in such a manner that said engine is hung from said main frame (5) through said engine hanger (7), said engine hanger (7) having an upper end portion mounted to said main frame (5) and having a lower end portion mounted to said engine, characterized in that a minimum width portion (W) is provided at an intermediate portion of said engine hanger (7) in the vertical direction, and a twisting center of said engine hanger (7) is positioned at said minimum width portion.

Full Text

The present invention relates to an engine supporting structure for a motor bicycle. A prior art engine supporting structure for a motor-bicycle has been disclosed in Japanese Utility Model Laid-open No. Sho 62-66898, wherein an engine hanger is provided integrally"with a radiator mounting stay in a motor-bicycle. The engine hanger has the upper end portion mounted at two front and rear positions to a main frame, and has the lower end portion connected at one position to an engine. [Problem to be Solved by the Invention] The above-described engine hanger, which supports an engine as a vibrator, is required for a relatively large rigidity. As a result, the size and weight of the engine hanger have come to be increased. Accordingly, an object of the present invention is to provide an engine hanger capable of supporting an engine with a rigidity smaller than that of the prior art engine hanger. [Means for Solving the Problem] To achieve the above object, according to the present invention, there is provided an engine supporting structure for a motor-bicycle, wherein a minimum width portion is provided at an intermediate portion of an engine hanger in the vertical direction, and a twisting center of the engine hanger is positioned at the minimum width portion. Accordingly, there is provided an engine supporting structure for a motor bicycle having : a main frame extending rearward from a head pipe; an engine disposed under said main frame; and an engine hanger for supporting said engine in such a manner that said engine is hung from said main frame through said engine hanger, said engine hanger having an upper end portion mounted to said main frame and having a lower end portion mounted to said engine, characterized in that a minimum width portion is provided at an intermediate portion of said engine hanger in the vertical direction, and a twisting center of said engine hanger is positioned at said minimum width portion. In this engine supporting structure, a weight reducing portion may be provided at a position higher than the minimum width portion of the engine hanger. The weight reducing portion in the present invention may include both a hole and a thin wall portion. [Function] According to the present invention, the twisting center of the engine hanger is set at the minimum width portion positioned at the intermediate portion of the engine hanger in the vertical direction. As a result, when a vehicular body and an engine are vibrated, each amplitude of vibration in the vertical direction hanger is made smaller. Thus, it becomes possible to lower the rigidity of the entire engine hanger,"and hence to reduce the weight and size of the entire engine hanger. In this engine supporting structure, the twisting center can be adjusted to be further moved to the main frame side, by provision of the weight reducing portion in the engine hanger at a position higher than the minimum width portion. [Brief Description of the Drawings] [Fig. 1] A side view of an embodiment of an engine hanger of the present invention. [Fig. 2] A sectional view taken on line 2-2 of Fig. I. [Fig. 3] A side view showing the entire configuration of a motor-bicycle to which the present invention is applied. [Fig. 4] A view showing a portion of a main frame, on which the engine hangers are mounted. [Embodiment] One embodiment of the present invention will be described with reference to the drawings. Fig. 3 shows a side surface of the front portion of a motor-bicycle having a diamond type frame structure to which the present invention is applied. In this figure, the upper portion of a front fork 2 for supporting a front wheel 1, which is connected to a head pipe 3, is operable by a handle 4. A main frame 5 extends rearward from the head pipe 3, and a fuel tank 6 is supported on the main frame 5. The upper portion of a downward projecting engine hanger 7 is mounted on one side surface of the main frame 5. The engine hanger 7 according to the present invention is formed substantially into a T-sha'pe in a side view. The lower end portion of the engine hanger 7 is connected to a mounting portion 9 provided on a cylinder head cover 8 of a four-cycle engine. A carburetor 11 is connected to the intake side of a cylinder head 10 of the engine, and the upstream side of the carburetor 11 is connected to an air cleaner 12. On the other hand, an exhaust pipe 13 is connected to the exhaust side of the cylinder head 10. A down-pipe 16 extends obliquely in the vertical direction from the head pipe 3 to the front side of the engine. A front portion mounting bracket 17 is mounted to the lower end portion of the down-pipe 16 on the front side of a crank case 15 mounting a cylinder block 14. In addition, reference numerals 18, 19 indicate mounting portions of the front portion mounting bracket 17. The rear end portion of the main frame 5 is branched right and left into pivot frames 21. The pivot frames 21 extend in the vertical direction. The rear portion of a mission case 20 integrated with the crank case 15 is mounted on each pivot frame 21 by means of upper and lower mounting portions 22, 23. A drive sprocket 24 provided on the mission case 20 drives a driven sprocket (not shown) of a rear wheel (not shown) through a chain 25. The front end portion of a rear swing arm 27 is turnably supported on pivot portions 26 of the pivot frames 21. Fig. 4 is a view, as seen from the upper side, of a portion of the main frame 5 on which the engine hangers 7 are mounted, with parts partially broken away. The main frame 5 is disposed in the longitudinal direction along the center of the vehicular body, and a pair of the engine hangers 7 are mounted on both the sides of the main, frame 5. The engine hanger 7 abuts both ends of each of a pair of front and rear collars 30 crossing the main frame 5 and is fixed thereto by means of a bolt 31 and a nut 32. The lower portion of the engine hanger 7 extends downward, and the lower end of the engine hanger 7 is similarly fixed to both ends of a collar 33 by means of a bolt 34 and a nut 35. The collar 33 crosses the mounting portion 9 for mounting the engine, in the width direction of the vehicle. Fig. 1 is a side view of the engine hanger 7, and Fig. 2 is a sectional view taken on line 2-2 of Fig. 1. As shown in these figures, the engine hanger 7 is formed of a flat plate like member. Mounting holes 40, 41 are formed fore and aft in the upper portion of the engine hanger 7, while a mounting hole 42 is formed in the lower portion of the engine hanger 7. End portions near the upper front mounting hole 40 and the upper rear mounting hole 41 form small round portions 43, 44, respectively. An end portion near the lower mounting hole 42 forms a large round portion 45. The upper end line connecting the small round portion 43 to the small round portion 44 forms a round portion 46 curved inward of the engine hanger 7. The front end line connecting the small round portion 43 to the large round portion 45 forms a large round portion 47 curved inward of the engine hanger 7. Moreover, the rear end line connecting the small round portion 44 to the large round portion 45 also forms a large round portion 48 curved inward of the engine hanger 7. A neck portion 50 is formed by the round portions 47, 48 at a position lower than a line Ll connecting the centers of the mounting holes 40, 41 to each other. A twisting center 51 is formed at a position, being higher than the mounting hole 42, where the width of the neck portion 50 is minimized. A weight reducing hole 52 is formed on a line L2 connecting an approximately intermediate point of the line Ll to the center of the mounting hole 42 at a position near the mounting holes 40, 41. In addition, reference numeral 53 indicates a stay for a straightener. The small round portions 43, 44, the round portion 46, and the round portions 47, 48 lower the rigidity of the upper portion of the engine hanger 7. Moreover, the weight reducing portion 52 is formed in the upper portion of the engine hanger 7. Consequently, the twisting center 51 is moved relatively upward, and is set at the minimum width portion of the neck portion 50. The position of the twisting center 51 can be simply adjusted by changing the position and the size of the weight reducing hole 52. In addition, the plate thickness of the engine hanger 7 is set in accordance with the rigidity required for each kind of the vehicle. The function of this embodiment will be described below. When the upper and lower mounting portions of the engine hanger 7 vibrates in the width direction of the vehicular body due to vibration of the engine and the vehicular body, each amplitude of vibration is made smaller because the twisting center 51 is positioned at the intermediate portion of the engine hanger 7 in the vertical direction. Since the rigidity of the entire engine hanger 7 can be also lowered by provision of the round portions, the weight and size of the entire engine hanger 7 can be reduced. The position of the twisting center can be simply adjusted by changing the position and the size of the weight reducing hole 52. Although the preferred embodiment of the present invention has been described, such description is for illustrative purposes only, and it is to be understood that various changes in design may be made without departing from the spirit and the scope of the invention. For example, the engine hanger 7 is not limited to be formed of a flat plate like shape, but may be bent substantially into a crank shape in Fig. 4. The mounting collars may be previously welded to all or part of the mounting holes. Either of the round portions 47, 48 may be formed in a straight shape, so that the engine hanger 7 can be formed substantially into an L shape in a side view. The engine hanger 7 may be similarly formed in a Y-shape, P-shape or the like. The frame structure of the motor-bicycle to which the present invention is applied, is not limited to the diamond type but it may be of a cradle type. The weight reducing hole 52 shown in this embodiment is not necessarily provided. Namely, the position of the twisting center can be also adjusted by changing the shape and plate thickness of the engine hanger 7. In addition, the weight reducing hole 52 may be replaced with a. thin wall portion. [Effect of the Invention] In the engine supporting structure for a .motor-bicycle according to the present invention, a minimum width portion is provided at an intermediate portion of an engine hanger in the vertical direction, and a twisting center of the engine hanger is positioned at the minimum width portion. Since the twisting center of the engine hanger is set at the minimum width portion positioned at the intermediate portion in the vertical direction, when a vehicular body and an engine are vibrated, each amplitude of vibration in the vertical direction is made smaller. This leads to reduction in the vibration of the vehicular body. Accordingly, it becomes possible to lower the rigidity of the entire engine hanger, and hence to reduce the weight and size of the entire engine hanger. In this engine supporting structure, the twisting center can be adjusted to be further moved to the main frame side, by provision of the weight reducing portion in the engine hanger at a position higher than the minimum width portion. [Explanation of Characters] 5: main frame, 7: engine hanger, 8: cylinder head cover, 9; mounting portion, 40: mounting hole, 41: mounting hole, 42: mounting hole, 50: neck portion. 51: twisting center, 52: weight reducing hole We Claim: 1. An engine supporting structure for a motor bicycle having a main frame (5) extending rearward from a head pipe (3); an engine disposed under said main frame(5); and an engine hanger (7) for supporting said engine in such a manner that said engine is hung from said main frame (5) through said engine hanger (7), said engine hanger (7) having an upper end portion mounted to said main frame (5) and having a lower end portion mounted to said engine, characterized in that a minimum width portion (W) is provided at an intermediate portion of said engine hanger (7) in the vertical direction, and a twisting center of said engine hanger (7) is positioned at said minimum width portion. 2. An engine supporting structure as claimed in claim 1, wherein a weight reducing (52) portion is provided in said engine hanger (7) at a position higher than said minimum width portion. 3. An engine supporting structure substantially as herein described with reference to and as illustrated in the accompanying drawings.

Documents:

131-del-1996-abstract.pdf

131-del-1996-claims.pdf

131-del-1996-complete specification (granted).pdf

131-del-1996-correspondence-others.pdf

131-del-1996-correspondence-po.pdf

131-del-1996-description (complete).pdf

131-del-1996-drawings.pdf

131-del-1996-form-1.pdf

131-del-1996-form-13.pdf

131-del-1996-form-2.pdf

131-del-1996-form-3.pdf

131-del-1996-form-4.pdf

131-del-1996-form-6.pdf

131-del-1996-form-9.pdf

131-del-1996-gpa.pdf

131-del-1996-petition-123.pdf

131-del-1996-petition-124.pdf

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