JP6487889B2 - Support structure of unit swing type drive unit - Google Patents

Description

  The present invention relates to a support structure for a unit swing type drive unit.

  Patent Document 1 discloses a horizontal link type suspension device of a unit swing type drive unit in which an engine, a transmission device and wheels are integrated. This suspension device is connected to the vehicle body frame so as to be swingable about the first pivot axis and linked to the drive unit so as to be swingable about the second pivot axis between the vehicle body frame and the front portion of the drive unit. Is provided. The link arm is formed of a front link and a rear link that intersect in a V shape so as to be rotatable around an intermediate axis called an oleo link.

Japanese Patent Laid-Open No. 2-162186

  A damper that allows deflection in the rotational direction around the first pivot axis is coupled to the front link. A damper that allows deflection in the rotational direction around the second pivot axis is coupled to the rear link. Further, a damper that allows bending in the rotational direction around the intermediate shaft is coupled. The front link and the rear link approach or move away from each other within the range of deflection of the damper around the intermediate shaft, and absorb vibration generated when the drive unit travels. However, the beat vibration in which the vibration amplitude periodically changes due to the rotation vibration of the drive unit is not considered at all.

  The present invention provides a support structure for a unit swing type drive unit that can effectively absorb beat vibration in which the vibration amplitude periodically changes due to the mass imbalance between the engine of the drive unit and the rotating part of the transmission device. The purpose is to provide.

According to a first aspect of the present invention, it has been connected to the vehicle body pivotably in the first pivot axis, and an engine, a driven pulley which rotates at a rotational plane of offset from the cylinder axis of the engine in the width direction of the vehicle and Berukon automatic transmission, comprising a link arm connected pivotally at a second pivot axis to the drive unit and a wheel, unit swing type for suspending the swingably the drive unit vertically on the body in the support structure of the drive unit, to the first pivot axis, with elastically supports the outer tube of the link arm via a rubber bush, the first pivot axis, defining a predetermined gap between the outer cylinder the contact member which is arranged, the predetermined gap is set to contact with the size shrinkage of the rubber bushing to each other and the a becomes equal to or higher than a predetermined abutment member and the outer tube Is, the abutting member you restricting relative displacement of the outer cylinder relative to the first pivot axis in response to contraction of said rubber bush.

According to a second aspect, in addition to the configuration of the first aspect, wherein the abutment member is provided between the end surface of the outer cylinder and the vehicle body side bracket, while ensuring an interval in the axial direction of the first pivot shaft it is disposed a washer member abutting on the vehicle body side bracket and the front Kigai tube during the contraction of the rubber bushing.

According to the third aspect, in addition to the configuration of the first side surface, the abutting member is a collar attached to the first pivot shaft, and is fitted into the outer end of the outer cylinder to be connected to the outer cylinder. A collar that is disposed inside a bush having a bearing function forming an inner peripheral surface while securing a predetermined gap in a radial direction of the first pivot shaft, and abuts on the bush having a bearing function when the rubber bush is contracted. .

  According to the fourth aspect, in addition to the structure of any one of the first to third aspects, the rubber bush has an annular shape and has a lightening hole extending in the circumferential direction between the central hole and the outer cylinder. The elastic shaft of the hollow hole is disposed in a direction orthogonal to the caster axis of the front wheel.

  According to the fifth aspect, in addition to any one of the first to fourth aspects, the link arm is provided with an intermediate shaft, and a needle bearing is incorporated into the intermediate shaft. Support structure.

  According to the sixth aspect, in addition to the configuration of the fifth side, the support structure of the unit swing type drive unit includes a reinforcing member that reinforces the link arm between the left and right link arms and the first pivot shaft. Prepare.

  According to the seventh aspect, in addition to the configuration of the fifth or sixth side surface, a guard portion extending downward from the engine side attachment portion is integrally provided on the lower surface of the engine side link of the left and right link arms.

  According to the eighth aspect, in addition to the configuration of any one of the fifth to seventh aspects, a space is formed between the left and right link arms, and the engine accessory is passed through.

According to the first aspect, the driven pulley of the Belcon automatic transmission rotates on a rotating surface that deviates from the cylinder axis of the engine in the width direction of the vehicle, so that when the torque transmission ratio to the driven pulley is close to 1, The primary vibration and the vibration generated based on the mass imbalance on the driven pulley side are synchronized, and beat vibration is generated. At this time, the contact member and the outer cylinder come into contact with each other when the contraction of the rubber bush exceeds a predetermined level due to the torsion of the vehicle body caused by the beat vibration, and the force in the torsional direction is received by the contact member. As a result, lateral and vertical behavior is converted to vibration in the longitudinal direction, the maximum amplitude of the beat oscillation is reduced, the amplitude of the vibration beat to easily transmit vibrations in the longitudinal direction is reduced. It is possible to suppress and equalize the beat vibration consisting of the peaks and valleys of the periodic vibration generated by the engine drive system, and to improve the riding comfort. When the torque transmission ratio is less than 1, a predetermined gap is defined between the contact member and the outer cylinder, so that the contact member does not contact the outer cylinder, and the vibration of the engine is appropriately controlled by the rubber bush. Absorbed. It is possible to avoid the vibration on the engine side from being transmitted unnecessarily to the vehicle body side.

  According to the second aspect, the washer member provided on the end surface of the first pivot shaft outer tube converts the left and right vibrations of the drive unit into the front and rear vibrations to increase the minimum amplitude of the beat vibration and suppress the beat vibration. .

According to the third aspect, the collar abuts against the bush with a bearing function that forms the inner peripheral surface of the outer cylinder when the contraction of the rubber bush exceeds a predetermined value, and the force in the twisting direction is received by the collar. Thus the left and right directions torsion is suppressed, running stability is improved, and can you to reduce the maximum amplitude of the beat oscillation can be suppressed beat oscillation.

  According to the fourth aspect, the elastic shaft of the lightening hole is disposed in a direction perpendicular to the caster axis of the front wheel, so that the running stability can be improved and the maximum amplitude of the beat vibration can be reduced, Beating vibration can be suppressed.

  According to the fifth aspect, since the needle bearing provided on the intermediate shaft can swing around the intermediate shaft, the maximum amplitude of the beat vibration can be reduced and the beat vibration can be suppressed.

  According to the sixth aspect, since the link arm is reinforced by the reinforcing member between the left and right link arms and the first pivot shaft, the torsional rigidity of the link can be improved even if the intermediate shaft is independent on the left and right.

  According to the seventh aspect, since the guard portion extending downward from the engine side attachment portion is integrally provided on the lower surface of the engine side link, it is also useful for reinforcing the engine side link.

  According to the eighth aspect, since a space is formed between the left and right link arms and the engine auxiliary machine is passed through, the degree of freedom in layout is improved even if the engine is tilted forward and close to the link.

1 is a side view schematically showing a scooter type motorcycle according to an embodiment of a saddle-ride type vehicle. FIG. 2 is a horizontal sectional view taken along line 2-2 in FIG. 1 is an enlarged side view of a motorcycle schematically showing a support structure. It is a top view of the support structure observed from the bottom. It is an expanded sectional view showing roughly the structure of an intermediate shaft. It is sectional drawing which shows schematically the support structure which concerns on 1st Embodiment. It is sectional drawing which shows schematically the support structure which concerns on 2nd Embodiment. FIG. 6 is an enlarged cross-sectional view schematically showing a structure of an intermediate shaft according to another embodiment corresponding to FIG. 5. It is a schematic diagram which shows the relationship between the elastic shaft of a rubber bush, and the caster axis line of a front wheel.

Hereinafter, the implementation form of the present invention will be described with reference to the accompanying drawings. In the following description, front and rear, up and down, and left and right directions refer to directions viewed from a passenger on a motorcycle.

  FIG. 1 schematically shows a scooter type motorcycle according to an embodiment of a saddle type vehicle. The motorcycle 11 includes a body frame 12 and a body cover 13. The vehicle body frame 12 includes a head pipe 14 at the front end, a main frame 15 coupled to the head pipe 14 at the front end, a cross pipe 16 coupled to the rear portion of the main frame 15 and extending in the vehicle width direction, and the cross pipe 16 And a pair of left and right rear frames 17 extending in the vehicle front-rear direction. The head pipe 14 supports a front fork 18 that supports the front wheel WF so as to be rotatable about a horizontal axis, and a rod-shaped steering handle 19 that can be steered.

  The vehicle body cover 13 is attached to the vehicle body frame 12. An occupant seat 21 is mounted on the vehicle body cover 13 above the rear frame 17. The body cover 13 includes a front cover 22 that covers the head pipe 14 from the front, a leg shield 23 that is continuous from the front cover 22, and a main frame 15 between the passenger seat 21 and the front wheel WF that is continuous from the lower end of the leg shield 23. And a step floor 24 disposed above.

A unit swing type drive unit 25 is disposed in a space below the rear frame 17. The drive unit 25 is coupled to a bracket 26 coupled to the front end of the rear frame 17 via a support structure 27 so as to be swingable in the vertical direction. A rear wheel WR is supported at the rear end of the drive unit 25 so as to be rotatable about a horizontal axis. Between the rear frame 17 and the drive unit 25 at a position away from the support structure 27 and the bracket 26, the rear cushion unit 28 extends from the grounding point A of the rear wheel WR to the rear side of the cushion shaft B of the rear cushion unit 28. It is arranged so that the line is located. The drive unit 25 includes an air-cooled single-cylinder engine 29 and a transmission 31 that is connected to the engine 29 and the rear wheel WR and transmits the output of the engine 29 to the rear wheel WR. A transmission case 31 a of the transmission device 31 is coupled to the engine body 29 a of the engine 29.

  The engine body 29a of the engine 29 includes a crankcase 33 that supports the crankshaft 32 so as to be rotatable around a rotation axis, a cylinder block 34 coupled to the crankcase 33, a cylinder head 35 coupled to the cylinder block 34, A head cover 36 coupled to the cylinder head 35. An intake device 37 and an exhaust device 38 are connected to the cylinder head 35. The intake device 37 includes an air cleaner 39 supported by the transmission case 31 a and a throttle body 41 disposed between the air cleaner 39 and the cylinder head 35. A fuel injection valve 42 is attached to the upper side wall of the cylinder head 35. The exhaust device 38 includes an exhaust pipe 43 extending rearward from the lower side wall of the cylinder head 35 through the lower side of the engine main body 29a, and an exhaust muffler MF connected to the crankcase 33 connected to the downstream end of the exhaust pipe 43 (see FIG. 1).

  As shown in FIG. 2, a cylinder bore 44 is defined in the cylinder block 34. A piston 45 is fitted into the cylinder bore 44 so as to be slidable along the cylinder axis C. The cylinder axis C is slightly inclined upward. The crankshaft 32 is connected to the piston 45. The rotation axis Xis of the crankshaft 32 is directed in the vehicle width direction.

  A combustion chamber 46 is defined in the cylinder head 35. The combustion chamber 46 continues from the cylinder bore 44. The piston 45 faces the cylinder head 35 and partitions the combustion chamber 46 between the piston 45 and the cylinder head 35. An air-fuel mixture is introduced into the combustion chamber 46 via an intake device 37. The exhaust gas in the combustion chamber 46 is discharged through the exhaust device 38.

  The crankcase 33 is divided into a first case half 33a and a second case half 33b. The first case half 33a and the second case half 33b cooperate to partition the crank chamber 47. A crank of the crankshaft 32 is accommodated in the crank chamber 47. The first case half 33 a has a bearing 48 a that rotatably supports the crankshaft 32, while the second case half 33 b has a bearing 48 b that rotatably supports the crankshaft 32.

  A generator 49 is coupled to the crankcase 33. The generator 49 passes through the first case half 33a of the crankcase 33 and is fixed to the crankshaft 32 protruding from the first case half 33a. The generator 49 is surrounded by the rotor 51 and is connected to the crankshaft 32. And a stator 52 disposed around. The stator 52 is fixed to a support plate 53 fastened to the first case half 33a. The generator 49 generates an electric current according to the relative rotation between the rotor 51 and the stator 52.

  A cylindrical generator cover 54 surrounding the generator 49 is coupled to the first case half 33a. An air inlet 54 a is defined at the open end of the generator cover 54. A radiator 55 is disposed at the air inlet 54a. A cooling fan 56 is coupled to the outer surface of the rotor 51. The cooling fan 56 rotates in accordance with the rotation of the crankshaft 32, and the cooling air flows through the radiator 55.

The transmission 31 is housed in a transmission case 31a, and is an electronically controlled V-belt continuously variable transmission that changes the rotational power transmitted from the crankshaft 32 continuously. ) 57 and a reduction gear mechanism 59 that is housed in the transmission case 31a and decelerates the rotational power of the transmission 57 and transmits it to the axle 58 of the rear wheel WR. The rear wheel WR is disposed between the transmission case 31 a and the support arm 61. The support arm 61 extends continuously from the crankcase 33 toward the rear of the vehicle. The exhaust muffler MF is attached to the support arm 61. The axle 58 of the rear wheel WR is supported at both ends by the transmission case 31a and the support arm 61 so as to be rotatable about the axis.

  The transmission case 31 a includes a case main body 62 that is continuous from the second case half 33 b of the crankcase 33, a case cover 64 that is fastened to the case main body 62 and divides the transmission chamber 63 between the case main body 62, A gear cover 66 is provided that is fastened to the case main body 62 and defines a gear chamber 65 between the case main body 62 and the case main body 62. A transmission 57 is accommodated in the transmission chamber 63. A reduction gear mechanism 59 is accommodated in the gear chamber 65. The case main body 62 and the case cover 64 together constitute a mission case.

  The transmission 57 is disposed in the transmission chamber 63 and is attached to the crankshaft 32 as a drive shaft, and is disposed in the transmission chamber 63 and protrudes from the transmission chamber 63 to the gear chamber 65. And a driven pulley 69 attached to the driven shaft 68. A continuous V belt 71 is wound around the driving pulley 67 and the driven pulley 69 without interruption. As will be described later, the belt winding diameter of the drive pulley 67 is variably electronically controlled by the action of the actuator unit 72. As will be described later, the belt winding diameter of the driven pulley 69 changes according to the change in the belt winding diameter of the driving pulley 67.

The drive pulley 67 includes a fixed sheave 73 that is fixed to the crankshaft 32 and a movable sheave 74 that is supported by the crankshaft 32 so as to be movable in the axial direction of the crankshaft 32 while facing the fixed sheave 73. The movable sheave 74 is disposed between the second case half 33 b of the crankcase 33 and the fixed sheave 73. The V belt 71 is wound between the fixed sheave 73 and the movable sheave 74. The movable sheave 74 has a movable sheave boss 74 a that receives the crankshaft 32. The movable sheave boss 74 a extends from the sheave body that receives the V-belt 71 toward the second case half 33 b of the crankcase 33 . The transmission 57 includes a first shift mechanism 75a and a second shift mechanism 75b including the actuator unit 72 described above. In accordance with the functions of the first shift mechanism 75a and the second shift mechanism 75b, the axial movement of the movable sheave 74 is realized, and the winding radius of the V-belt 71 changes.

  The driven pulley 69 has a cylindrical shape coaxial with the driven shaft 68, and has an inner cylinder 76 attached to the coaxial driven shaft 68 and a cylindrical shape coaxial with the driven shaft 68, and is coaxially attached to the inner cylinder 76. The outer cylinder 77 is provided. The inner cylinder 76 is supported by the driven shaft 68 so as to be relatively rotatable. The outer cylinder 77 is supported by the inner cylinder 76 so as to be relatively rotatable and axially displaceable. A fixed sheave 78 is coaxially fixed to the inner cylinder 76. A movable sheave 79 is coaxially fixed to the outer cylinder 77. The movable sheave 79 faces the fixed sheave 78, and the movable sheave 79 approaches or moves away from the fixed sheave 78 in accordance with the relative axial displacement of the outer cylinder 77 and the inner cylinder 76. A V-belt 71 is wound between the fixed sheave 78 and the movable sheave 79.

  A centrifugal clutch 81 is attached to the driven shaft 68. The centrifugal clutch 81 includes a clutch plate 81 a fixed to the inner cylinder 76. A string spring 82 is disposed between the clutch plate 81a and the movable sheave 79. The string spring 82 exerts an elastic force that presses the movable sheave 79 toward the fixed sheave 78. When the winding radius of the V-belt 71 is increased by the driving pulley 67, the movable sheave 79 is moved away from the fixed sheave 78 against the elastic force of the string-wound spring 82 in the driven pulley 69 and the winding radius of the V-belt 71 is decreased.

  The centrifugal clutch 81 includes an outer plate 81 b that is fixed to the driven shaft 68. The outer plate 81b is opposed to the clutch plate 81a. When the clutch plate 81a rotates, the outer plate 81b is coupled to the clutch plate 81a by the action of centrifugal force. Thus, the rotation of the driven pulley 69 is transmitted to the driven shaft 68. When the engine speed exceeds the set speed, the centrifugal clutch 81 establishes a power transmission state.

  The reduction gear mechanism 59 is disposed between the drive gear 83 fixed to the driven shaft 68 protruding into the gear chamber 65, the final gear 84 fixed to the axle 58 of the rear wheel WR, and the drive gear 83 and the final gear 84. Idle gears 85a and 85b. The idle gears 85a and 85b are fixed to a common relay shaft 86. The drive gear 83 meshes with the idle gear 85a, and the final gear 84 meshes with the idle gear 85b. Thus, the rotation of the driven shaft 68 is decelerated and transmitted to the axle 58 of the rear wheel WR.

  As shown in FIG. 3, the support structure 27 is connected to the cross pipe 16 of the vehicle body frame 12 by a first pivot shaft 87 and swings to the drive unit 25 by a second pivot shaft 88 parallel to the first pivot shaft 87. Link arms 89a and 89b that are pivotally supported and are separated in the left-right direction are provided. An intermediate shaft 91 is provided on the link arms 89a and 89b. The axis of the first pivot shaft 87 and the axis of the second pivot shaft 88 extend parallel to the axle 58 of the rear wheel WR. The axis of the intermediate shaft 91 is located parallel to the axis of the first pivot shaft 87 and the axis of the second pivot shaft 88.

  The link arms 89a and 89b are connected to the front link 92 connected to the vehicle body side bracket 26 so as to be swingable around the axis of the first pivot shaft 87, and to the front link 92 so as to be rotatable about the intermediate shaft 91. And a rear link 94 connected to the engine side bracket 93 so as to be rotatable around the two pivot shafts 88. A first pivot shaft outer cylinder 95 is coupled to the front end of the front link 92. The front link 92 may be welded to the first pivot shaft outer cylinder 95, for example. The first pivot shaft 87 passes through the first pivot shaft outer cylinder 95. A second pivot shaft outer cylinder 96 is coupled to the rear end of the rear link 94. The rear link 94 may be welded to the second pivot shaft outer cylinder 96, for example. The second pivot shaft 88 passes through the second pivot shaft outer cylinder 96. The axis Cm of the intermediate shaft 91 is disposed at a position (position close to the ground) lower than the horizontal plane H1 including the axis of the first pivot shaft 87 and the horizontal plane H2 including the axis of the second pivot shaft 88. .

  The first pivot shaft outer cylinder 95 includes a first rotation stopper 97a extending in the first direction in the circumferential direction of the cross pipe 16, and a second direction extending in the second direction opposite to the first direction in the circumferential direction of the cross pipe 16. The rotation stopper 97b is fixed. The first rotation stopper 97 a has a partial cylindrical contact surface 98 that spreads along the cylindrical surface of the cross pipe 16. The first rotation stopper 97 a contacts the pedestal on the cross pipe 16 at the contact surface 98. Similarly, the second rotation stopper 97b has a partial cylindrical contact surface 99 that expands following the cylindrical surface of the cross pipe 16. The second rotation stopper 97 b comes into contact with the pedestal on the cross pipe 16 at the contact surface 99. The first rotation stopper 97 a and the second rotation stopper 97 b prevent the rotation of the first pivot shaft outer cylinder 95 around the first pivot shaft 87.

  A guard portion 101 that extends from the lower surface of the rear link 94 toward the lower side of the engine side bracket 93 is integrally provided on the rear link 94 of the left and right link arms 89a (89b). The guard part 101 should just extend toward the ground rather than the virtual horizontal surface H3 which contact | connects the lower end of the exhaust pipe 43, for example. The contact between the exhaust pipe 43 and the ground can be avoided by the action of the guard portion 101.

  As shown in FIG. 4, the first pivot shaft outer cylinder 95 is fastened to the vehicle body side bracket 26 with bolts 102 and nuts 103. The first pivot shaft outer cylinder 95 is disposed between the vehicle body side brackets 26. A nut 103 is fastened to the bolt 102 and the shaft portion of the bolt 102 is fixed to the vehicle body side bracket 26. Here, the shaft portion of the bolt 102 functions as the first pivot shaft 87.

  The second pivot shaft outer cylinder 96 is fastened to the engine side bracket 93 with bolts 104 and nuts 105. The second pivot shaft outer cylinder 96 is disposed between the engine side brackets 93. The nut 105 is fastened to the bolt 104, and the shaft portion of the bolt 104 is fixed to the engine side bracket 93. The shaft portion of the bolt 104 functions as the second pivot shaft 88.

  A cylindrical body 106 is fixed to the rear end of the front link 92. The axial center of the cylindrical body 106 is installed in parallel to the first pivot shaft 87. A plate piece 107 sandwiching the cylindrical body 106 is formed at the front end of the rear link 94. When the nut 109 is fastened to the bolt 108, the cylindrical body 106 is connected to the plate piece 107 so as to be rotatable around the axis. The shaft portion of the bolt 108 functions as the intermediate shaft 91.

  Between the left and right link arms 89a and 89b and the first pivot shaft 87, reinforcing members 111 are arranged on the left and right. The reinforcing member 111 passes through the front link 92 from the outside to the inside in parallel to the axis of the first pivot shaft 87, and is coupled to the outer periphery of the first pivot shaft outer cylinder 95 at the inner end. The inner end of the reinforcing member 111 is welded to the first pivot shaft outer cylinder 95. The outer ends of the reinforcing members 111 are individually welded to the left and right link arms 89a and 89b. The reinforcing member 111 increases the rigidity of the support structure 27. A space is formed between the left and right link arms 89a and 89b. The exhaust pipe 43 is passed between the left and right link arms 89a and 89b.

  As shown in FIG. 5, the collar 112 is inserted inside the cylindrical body 106 of the front link 92 between the plate pieces 107. The shaft portion of the bolt 108 passes through the collar 112. A tube bush 113 is attached to the outer periphery of the collar 112. A tube bush 113 surrounds the collar 112. Thus, the tube bush 113 is sandwiched between the cylindrical body 106 and the collar 112 of the front link 92. The plate piece 107 is in rigid contact with the end face of the cylindrical body 106. Accordingly, although the cylindrical body 106 is allowed to rotate around the axis of the bolt 108, the cylindrical body 106 is prevented from sliding or twisting in the axial direction with respect to the axial portion of the bolt 108. The cylinder bushing 106 is allowed to move relative to the axial portion of the bolt 108 along a virtual plane orthogonal to the axial center of the bolt 108 by the action of the tube bush 113.

  As shown in FIG. 6, the support structure 27 according to the first embodiment includes a rubber bush 114 that is sandwiched between the body frame 12 and the first pivot shaft outer cylinder 95 around the first pivot shaft 87. The rubber bush 114 is attached to both ends of the first pivot shaft 87. Each rubber bush 114 is located outside in the vehicle width direction with respect to the two link arms 89a and 89b. The rubber bush 114 has a predetermined elasticity. Thus, the link arms 89a and 89b are elastically supported by the body frame 12 by the rubber bush 114.

  The support structure 27 includes a tube bush 115 sandwiched between the drive unit 25 and the second pivot shaft outer cylinder 96 around the second pivot shaft 88. The tube bush 115 is attached to the second pivot shaft 88 in the engine side bracket 93. The tube bush 115 has a predetermined elasticity. Thus, the link arms 89a and 89b are elastically supported by the drive unit 25 by the tube bush 115.

  The support structure 27 is disposed at both ends of the first pivot shaft 87, and a contact member 116 that rigidly receives the vehicle body side bracket 26 and the first pivot shaft outer cylinder 95 on a surface orthogonal to the axis of the first pivot shaft 87. Is provided. Here, the abutting member 116 is inserted on the first pivot shaft 87 in a floating state in the axial direction between the vehicle body side bracket 26 and the end surface of the first pivot shaft outer cylinder 95 via a minute gap. It is composed of a resin washer member 117 capable of contacting the side bracket 26 and the first pivot shaft outer cylinder 95.

  A predetermined gap 118 is defined in the axial direction between the washer member 117, the first pivot shaft outer cylinder 95 and the rubber bush 114. The gap 118 is set to a size such that the first pivot shaft outer cylinder 95 and the washer member 117 come into contact with each other when the axial deformation of the rubber bush 114 exceeds a predetermined level in response to the radial collapse of the rubber bush 114. . Therefore, when the first pivot shaft outer cylinder 95 is displaced relative to the first pivot shaft 87 and the rubber bush 114 contracts beyond a predetermined level, the deformation of the rubber bush 114 is stopped.

  Next, the operation of this embodiment will be described. When the engine 29 is operated, the crankshaft 32 rotates. The rotation of the crankshaft 32 is transmitted from the drive pulley 67 to the driven pulley 69. When the centrifugal clutch 81 is connected, the driving force is transmitted to the axle 58. The rear wheel WR is driven to rotate.

Here, when the movable sheave 74 approaches the fixed sheave 73 with the drive pulley 67, the V-belt 71 moves away from the rotation axis of the crankshaft 32. The transmission ratio of the driving force from the driving pulley 67 to the driven pulley 69 changes continuously. When the torque transmission ratio from the driving pulley 67 to the driven pulley 69 is close to 1, primary vibration of the engine body 29a, that is, vibration generated when the crankshaft 32 makes one rotation, and direction and transmission of the primary vibration of the engine body 29a. When vibration based on the mass imbalance of the rotating part of the outer plate 81b of the centrifugal clutch 81 or the driven pulley 69 on the driven shaft 68 side on the device 31 side is generated in the same direction, a large vibration is generated synchronously and beats. Vibration occurs. Since the cylinder axis C of the engine 29 and the rotating surface of the driven pulley 69 are biased in the width direction of the vehicle as shown in FIG. 2, a whirling vibration that twists with respect to the vehicle body is generated.

  At this time, in the support structure 27, the washer member 117 is firmly in contact with the bracket 26 on the vehicle body side and the first pivot shaft outer cylinder 95 on the link arm 89 a, 89 b side, so that the moving direction of the link arm 89 a, 89 b is restricted. Then, the left / right and up / down behavior of the drive unit 25 is converted into vibration in the front / rear direction. In addition, since the link arms 89a and 89b are elastically supported by the bracket 26 on the vehicle body side, vibration in the front-rear direction is easily transmitted, the maximum amplitude of the beat vibration is reduced, and the beat vibration of the engine drive system is suppressed. Riding comfort is enhanced.

As shown in FIG. 7, the support structure 27 a according to the second embodiment includes a rubber bush 121 that is sandwiched between the vehicle body frame 12 and the first pivot shaft outer cylinder 95 around the first pivot shaft 87. The rubber bush 121 is attached to both ends of the first pivot shaft 87. Each rubber bush 121 is located on the outer side in the vehicle width direction than the two link arms 89a and 89b. The rubber bush 121 has a predetermined elasticity. The rubber bush 121 has a small diameter portion 121a having an outer diameter smaller than the inner diameter of the first pivot shaft outer cylinder 95 at least at the outer end. An extension collar 122 is attached to the first pivot shaft 87 adjacent to the outer end of the small diameter portion 121a. The outer diameter of the extension collar 122 is set smaller than the outer diameter of the small diameter portion 121a .

  A bush 123 having a bearing function is fitted into the outer end of the first pivot shaft outer cylinder 95. The bush 123 includes a main body 123a that is press-fitted into the first pivot shaft outer cylinder 95, and a flange 123b that is formed integrally with the outer end of the main body 123a and extends in the radial direction. The flange 123 b contacts the outer end of the first pivot shaft outer cylinder 95. A through hole 124 is defined in the main body 123 a coaxially with the first pivot shaft outer cylinder 95. The small-diameter portion 121a of the rubber bush 121 is fitted at least partially into the through hole 124 from the inner end of the main body 123a. A predetermined gap g is defined in the radial direction between the main body 123 a and the extension collar 122. When the contraction of the rubber bush 121 exceeds a predetermined value, the bush 123 comes into contact with the extension collar 122 and stops the deformation of the rubber bush 121. Other configurations are the same as those of the support structure 27 described above.

When beat vibration is generated in the vehicle during operation of the engine 29, the torsion is generated in the lateral direction. When the contraction of the rubber bush 121 exceeds a predetermined value, the bush 123 abuts against the extension collar 122 and stops the deformation of the rubber bush 121. Therefore, it is possible to suppress the torsion in the left-right direction, improve running stability, and minimize the beat vibration. The amplitude can be increased and beat vibration can be suppressed.

  As shown in FIG. 8, a needle bearing 126 may be incorporated in the intermediate shaft 91. The needle bearing 126 includes an inner cylinder 126a coupled to the shaft portion of the bolt 108, an outer cylinder 126b coupled to the front link 92, and a plurality of needles 127 sandwiched between the inner cylinder 126a and the outer cylinder 126b. . The shaft portion of the bolt 108 is fitted into the inner cylinder 126a. The axis of the needle 127 is arranged in parallel with the axis of the bolt 108. Thus, since the front link 92 and the rear link 94 are relatively rotated around the intermediate shaft 91 by the needle bearing 126, the maximum amplitude of the beat vibration can be reduced and the beat vibration can be suppressed.

  As shown in FIG. 9, a through hole 128 is defined in the rubber bush 114 coaxially with the first pivot shaft outer cylinder 95. The bolt 102 of the first pivot shaft 87 passes through the through hole 128. Between the through hole 128 and the first pivot shaft outer cylinder 95, the rubber bush 114 is partitioned with a hole 129 extending in the circumferential direction. The elastic shaft 131 of the lightening hole 129 is arranged in a direction orthogonal to the caster axis 132 of the front wheel WF. In setting the elastic shaft 131, a rigid portion 133 is defined between the lightening holes 129 in the circumferential direction. Thus, the elastic shaft 131 of the lightening hole 129 is arranged in a direction orthogonal to the caster axis 132 of the front wheel WF, so that the running stability can be improved and the maximum amplitude of the beat vibration can be reduced. Can be suppressed.

  As described above, according to the present embodiment, the support structure 27 of the unit swing type drive unit 25 is connected to the vehicle body (vehicle body frame 12) so as to be swingable about the axis of the first pivot shaft 87. 92 and a second link having an axis parallel to the axis of the first pivot shaft 87 and connected to the front link 92 so as to be rotatable about an intermediate shaft 91 having an axis parallel to the axis of the first pivot shaft 87. A rear link 94 coupled to the drive unit 25 so as to be rotatable about a pivot shaft 88; rubber bushings 114 and 121 sandwiched between the vehicle body (body frame 12) and the front link 92 about a first pivot shaft 87; An abutting member 116 that is disposed at both ends of the first pivot shaft 87 and that rigidly receives the vehicle body frame 12 and the front link 92 on a plane orthogonal to the axis of the first pivot shaft 87 is provided.

  DESCRIPTION OF SYMBOLS 12 ... Vehicle body (vehicle body frame), 25 ... Unit swing type drive unit, 26 ... (vehicle body side) bracket, 27 ... Support structure, 27a ... Support structure, 29 ... Engine, 43 ... Auxiliary machine (exhaust pipe), 57 ... Belcon Automatic transmission (electronically controlled V-belt continuously variable transmission), 87 ... first pivot shaft, 88 ... second pivot shaft, 89a ... (left) link arm, 89b ... (right) link arm, 91 ... intermediate shaft, 94 ... (engine side) rear link, 95 ... first pivot shaft outer cylinder, 101 ... guard part, 111 ... reinforcing member, 114 ... rubber bush, 116 ... contact member, 117 ... washer member, 121 ... rubber bush, 123 ... Bush with bearing function, 126 ... Needle bearing, 128 ... Through hole, 129 ... Thickening hole, 131 ... Elastic shaft, 132 ... Caster axis, WF ... Front wheel WR ... the wheels (the rear wheels).

Claims (8)

It is connected to the vehicle body (12) so as to be swingable around the first pivot shaft (87) , and rotates on a rotating surface that deviates in the vehicle width direction from the cylinder axis (C) of the engine (29) and the engine (29). driven and pulley (69) Berukon automatic transmission having (57), a wheel (WR) and the second pivot axis (88) links the swing is rotatably connected around the arm (89a in the driving unit (25) comprising a to 89b), and the support structure of the unit swing type drive unit that suspends the drive unit (25) so as to be swingable up and down on the vehicle body (12),
The first pivot shaft (87) elastically supports the outer cylinder (95) of the link arm (89a, 89b) via the rubber bush (114, 121) ,
Abutting members (116 , 122 ) for partitioning a predetermined gap (118, g) with the outer cylinder (95) are disposed on the first pivot shaft (87 ) ,
The predetermined gap (118, g) has such a size that the contact member (116, 122) and the outer cylinder (95) come into contact with each other when the rubber bush (114, 121) contracts beyond a predetermined level. The abutting members (116, 112) regulate relative displacement of the outer cylinder (95) with respect to the first pivot shaft (87) in response to contraction of the rubber bush (114, 121). <br/> A support structure for a unit swing type drive unit. 2. The support structure for a unit swing type drive unit according to claim 1, wherein the contact member (116) is disposed between the first pivot shaft between a vehicle body side bracket (26) and an end surface of the outer cylinder (95). disposed while securing a distance (118) in the axial direction (87), said rubber bush said vehicle body side bracket when the (114) contraction (26) and before Kigai tube (95) in contact with the washer member (117) A structure for supporting a unit swing type drive unit. The support structure of a unit swing type drive unit according to claim 1, wherein the contact member (122) is a collar (122) attached to the first pivot shaft (87), and the outer cylinder (95). ) On the inner side of the bush (123) with a bearing function that forms the inner peripheral surface of the outer cylinder (95), and a predetermined gap (g) in the radial direction of the first pivot shaft (87 ). A support structure for a unit swing type drive unit, characterized in that it is a collar (122) that is arranged while securing the rubber bush (121) and abuts against the bush (123) with a bearing function when the rubber bush (121) contracts.   The support structure of the unit swing type drive unit according to any one of claims 1 to 3, wherein the rubber bush (114) is annular, and is provided between a central hole (128) and an outer cylinder (95). Characterized in that it has a hollowing hole (129) extending in the direction, and the elastic shaft (131) of the hollowing hole (129) is arranged in a direction perpendicular to the caster axis (132) of the front wheel (WF). Support structure for unit swing type drive unit.   The support structure of the unit swing type drive unit according to any one of claims 1 to 4, wherein the link arm (89a, 89b) is provided with an intermediate shaft (91), and the intermediate shaft (91) is provided with a needle bearing ( 126) A structure for supporting a unit swing type drive unit.   6. The support structure for a unit swing type drive unit according to claim 5, wherein the link arm (89a, 89b) is reinforced between the left and right link arms (89a, 89b) and the first pivot shaft (87). A support structure for a unit swing type drive unit, comprising a reinforcing member (111).   The support structure of the unit swing type drive unit according to claim 5 or 6, wherein the guard portion (101) extends below the engine side attachment portion on the lower surface of the engine side link (94) of the left and right link arms (89a, 89b). A support structure for a unit swing type drive unit, wherein The support structure for a unit swing type drive unit according to any one of claims 5 to 7, wherein a space is formed between the left and right link arms (89a, 89b), and an auxiliary machine for the engine (29) ( 43) A support structure for a unit swing type drive unit, which is passed through.

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