Power transmission device
Patent Information
- Application Number
- DE112017007335
- Authority / Receiving Office
- DE · DE
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2017-03-29
- Publication Date
- 2024-12-24
- Estimated Expiration
- 2037-03-29
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
[0001] The present invention relates to a power transmission device for transmitting power.
[0002] Some power transmission devices have a damper mechanism that uses an elastic element.
[0003] So far, there is one example where different types of elastic elements are used in combination as such an elastic element.
[0004] JP 2002 - 147 484 A discloses a damper mechanism comprising a plurality of damper pairs, each having a combination of a coil spring and a rubber element, which are elastically deformable to different degrees and have different elastic moduli and which act linearly, wherein the damper pairs are arranged one behind the other along circumferential directions.
[0005] DE 34 06 054 A1 discloses a torsional damping device with coaxially arranged components that can be rotated relative to one another within a predetermined angular spring travel. The rotation between the components occurs against spring means arranged in the circumferential direction. The spring means acting in the circumferential direction comprise a block made of elastic material, such as rubber, which is arranged substantially tangentially to a circumference of the arrangement.
[0006] DE 102 21 599 A1 discloses a clutch disc assembly with a drive rotary element, a driven rotary element, and a resilient coupling mechanism. The resilient coupling mechanism is arranged between the rotary elements. These elements and the mechanism form a damper mechanism for damping torsional vibrations while transmitting torque.
[0007] US 5,169,357 A1 discloses a damping device with two coaxial parts. These coaxial parts are movable in a relative rotation. The relative rotation is limited by an elastic means against which the relative rotation takes place. The elastic means consist of two annular blocks, each of which is arranged between a tooth of a toothing of the first coaxial part and a tooth of a toothing of the second coaxial part. These blocks are arranged such that they are compressed by the adjacent teeth of the other toothing, thus enabling damping of torsional vibrations.
[0008] US Pat. No. 7,334,553 B2 shows a differential gear drive gear with a damping element. A bushing part and a gear part are arranged coaxially with each other. The bushing part and the gear part are elastically coupled by damping rubbers and the spring damper, so that a torsional force can be transmitted while avoiding torsional vibrations.
[0009] The coil springs act under a low torque load, and the rubber elements act under a high torque load to absorb shocks, depending on the high or low torque load. If coil springs acting linearly are arranged circumferentially to support torque loads, the coil springs must be kept as linear as possible for their elasticity to function properly. Therefore, coil springs are inherently short and thus cannot be elastically deformed to a high degree, making it difficult to maintain a relatively large stroke.
[0010] Multiple short coil springs arranged sequentially along the circumferential directions make it possible to maintain a large stroke. However, the damper mechanism consists of an increased number of parts, is structurally complex, has a large size, and is expensive.
[0011] The present invention was made in view of the above problems. It is an object of the present invention to provide a power transmission device including a shock absorbing mechanism with a simple structure and a small size, capable of absorbing shocks in a large stroke under a low torque load and effectively absorbing shocks in a small stroke under a high torque load.
[0012] To achieve the above object, according to the present invention, there is provided a power transmission device comprising: a first rotor and a second rotor rotatably and coaxially arranged with a central axis of rotation and facing each other; a single arc spring which is elastically deformable to a high degree and has a small modulus of elasticity, the arc spring being interposed between the first rotor and the second rotor to urge the first rotor and the second rotor in opposite sides in a rotational direction; a first pressure projection protruding from the first rotor and a second pressure projection protruding from the second rotor, the first pressure projection and the second pressure projection being arranged in relative positions on superimposed rotational trajectories; and a rubber member elastically deformable to a small extent and having a large modulus of elasticity, the rubber member being interposed between the first pressing projection and the second pressing projection with gaps therebetween.
[0013] In this arrangement, the single arc spring is interposed between the first rotor and the second rotor, which are arranged coaxially with the central rotational axis and in facing relation to each other, to urge the first rotor and the second rotor in opposite sides in a rotational direction. The first urging protrusion protruding from the first rotor and the second urging protrusion protruding from the second rotor are arranged in relative positions on superimposed rotational trajectories, and the rubber member is interposed between the first urging protrusion and the second urging protrusion with gaps therebetween. When a torque load is applied to the first rotor and the second rotor, causing the first rotor and the second rotor to rotate relative to each other, the arc spring, which is highly elastically deformable and has a small elastic modulus, is initially elastically deformed under compression.When the torque load increases, the first pressure protrusion and the second pressure protrusion of the second rotor reduce the gap between them, pinching the rubber member inserted with gaps between them, whereupon the rubber member, which is deformable to a small extent and has a large elastic modulus, is elastically deformed under compression.
[0014] While the torque load is small, the arc spring, which is highly elastically deformable and has a small modulus of elasticity, effectively absorbs shocks in a large stroke.
[0015] As the torque load increases, the rubber element, which is elastically deformable to a small extent and has a large elastic modulus, undergoes elastic deformation under compression. The rubber element effectively absorbs a larger shock for smooth power transmission.
[0016] In other words, the arc spring works under a low torque load and the rubber element works under a high torque load to effectively absorb shocks depending on the high or low torque load for smooth power transmission at all times.
[0017] The arc spring comprises an arc-shaped coil spring. Although the arc spring, which is inserted between the first rotor and the second rotor, is single, it can be set to a large elastic operating angle (stroke) within which it is elastically deformable to properly function its elasticity. Therefore, it is possible to provide a shock absorption mechanism with a simple structure and small size, consisting of a small number of parts.
[0018] In the above arrangement, the first rotor and the second rotor may have a first receiving groove and a second receiving groove having an identical arcuate shape defined respectively in their first facing surface and their second facing surface, which are arranged close to each other and in a facing relationship; and the arc spring may have halves respectively received in the first receiving groove and the second receiving groove, and is interposed between the first rotor and the second rotor.
[0019] In this arrangement, since the arc spring is inserted between the first rotor and the second rotor with the respective halves received in the first receiving groove and the second receiving groove, respectively, a compression structure of the arc spring for urging the first rotor and the second rotor in opposite sides in a rotational direction and a holding structure of the arc spring can be composed of a minimum number of simple parts.
[0020] In the above arrangement, the rubber member may be fitted over both the first pressing projection and the second pressing projection.
[0021] In this arrangement, since the rubber member is fitted over both of the first pressing protrusion and the second pressing protrusion, the rubber member is easily mounted on both of the first pressing protrusion and the second pressing protrusion without using special mounting members, and is firmly held between the first pressing protrusion and the second pressing protrusion.
[0022] In the above arrangement, the first rotor may have: an arcuate groove defined in the first facing surface substantially on the same circumference as the first receiving groove; a pair of first pressing projections disposed in the arcuate groove, respectively, near circumferentially opposite ends of the arcuate groove; and the rubber member fitted over each of the first pressing projections; and the second rotor can have: the second receiving groove open in the second facing surface; and the second pressing projection projecting from the circumferentially nearly central portion of an arcuate surface of the second facing surface corresponding to the arcuate groove.
[0023] In this arrangement, on the first rotor, the first receiving groove is open in the first facing surface, and the arcuate groove defined therein, which is substantially concentric with the first receiving groove, is open in the first facing surface. The paired first pressing protrusions are arranged in the arcuate groove near its both ends in the circumferential direction, and the rubber member is fitted over each of the paired first pressing protrusions. On the second rotor, the second receiving groove is open in the second facing surface, and the second pressing protrusion protrudes from the circumferentially nearly central portion of the arcuate surface of the second facing surface corresponding to the arcuate groove. Therefore, the second pressing protrusion of the second rotor is sandwiched between the rubber member fitted over each of the paired first pressing protrusions of the first rotor.Under high torque load, the second compression protrusion on each of the paired first compression protrusions clamps the rubber element. The rubber element, which is elastically deformable to a small extent and has a high elastic modulus, is elastically deformed under compression and effectively absorbs a larger shock for smooth power transmission.
[0024] In the above arrangement, the rubber member fitted over each of the first pressing projections can be received in the arcuate groove.
[0025] With this arrangement, since the rubber member fitted over the first pressing protrusion is received in the arcuate groove, the rubber member does not protrude outward from the first facing surface. Upon relative rotation of the first rotor and the second rotor, the circumferential end edges of the second receiving groove in the second rotor do not physically interfere with the rubber member, thus preventing damage to the rubber member and affecting its durability.
[0026] In the above arrangement, the first rotor may have a disc shape and has a pair of the arcuate grooves defined on opposite portions of the first receiving groove therein transverse to the central rotation axis; the first rotor may have a machining clearance for unbalance adjustment behind the first receiving groove which receives one half of the arc spring therein; and the second rotor may have a disc shape and may have a machining clearance for unbalance adjustment transverse to the central axis of rotation opposite to the second receiving groove.
[0027] With this arrangement, since the disc-shaped first rotor has a pair of arcuate grooves transverse to the central rotation axis and opposite portions of the first receiving groove, the first rotor tends to be unbalanced due to its heavier weight on the first receiving groove side. The machining clearance for unbalance adjustment behind the first receiving groove is cut off to reduce unbalance, making the first rotor balanced and thereby preventing it from vibrating due to unbalance.
[0028] Since the second rotor having the disk shape tends to be unbalanced because it is heavier on the side transverse to the central rotation axis opposite to the second receiving groove due to the second receiving groove, the machining allowance for unbalance adjustment is arranged opposite to the second receiving groove and cut off to reduce the unbalance, which makes the second rotor balanced to thereby prevent itself from being vibrated due to the unbalance.
[0029] In the above arrangement, the first rotor comprises an engine-side rotor, wherein power is transmittable between itself and a crankshaft of an internal combustion engine; the second rotor comprises a starter-generator-side rotor, wherein power is transferable between itself and an input / output shaft of a starter-generator; the first pressure projection comprises an engine-side pressure projection; and the second pressure projection comprises a starter-generator-side pressure projection.
[0030] In this arrangement, under a low torque load applied to the engine-side rotor and the starter-generator-side rotor, which causes them to rotate with a small speed difference when the engine is in a normal operation, the arc spring, which is elastically deformable to a high degree and has a small elastic modulus, is compressively deformed and absorbs a smaller shock for smooth power transmission.
[0031] On the other hand, under a high torque load applied to the engine-side rotor and the starter-generator-side rotor, which causes them to rotate with a large speed difference when the engine is started, stalled, or operated for rapid acceleration, the rubber member, which is elastically deformable to a small extent and has a large elastic modulus, also compressively deforms the arc spring and absorbs a larger shock.
[0032] With the above arrangement, the starter-generator-side pressing protrusion disposed between a pair of rubber members fitted over a pair of engine-side pressing protrusions can be positioned closer to one of the rubber members spaced from the starter-generator-side pressing protrusion in the rotational direction when no relative torque load is applied to the engine-side rotor and the starter-generator-side rotor.
[0033] With this arrangement, when there is no speed difference between the engine-side rotor and the starter-generator-side rotor, the starter-generator-side thrust protrusion, located between the paired rubber elements, is positioned closer to one of the rubber elements spaced apart from it in the rotational direction. Consequently, for engine start, the starter-generator-side thrust protrusion acts earlier on the rubber element spaced apart from it in the rotational direction, resulting in reduced operating losses for early engine starting.
[0034] When the motorcycle is running normally, the arc spring undergoes a high degree of compression, absorbing a small shock for smooth power transmission until the starter-generator side thrust protrusion acts on the other rubber element positioned on the opposite side of the starter-generator side thrust protrusion in the direction of rotation. Noises such as gear play can be reduced in this way.
[0035] In the above arrangement, the starter-generator-side rotor may have a tubular shaft projecting from its central portion through the engine-side rotor and having the central rotation axis as a central axis; a helical gear may be slidably supported on the tubular shaft on its side transverse to the engine-side rotor opposite to the starter-generator-side rotor; the engine-side rotor facing the starter-generator-side rotor may be fixed to the helical gear; and a disc spring may be interposed between a sleeve which is prevented from shifting by a stopper engaging an outer periphery of the tubular shaft on a side of the engine-side rotor opposite to the helical gear, and the helical gear.
[0036] In this arrangement, the engine-side rotor is fixed to the helical gear slidably and rotatably supported on the rotor shaft of the starter-generator-side rotor. The disc spring is interposed between the collar, which is prevented from sliding by the stopper engaged with the outer periphery of the rotor shaft on an opposite side of the engine-side rotor with respect to the helical gear, and the helical gear. Therefore, the engine-side rotor is normally urged by the disc spring to move toward the disc-shaped starter-generator-side rotor and is allowed to move together with the helical gear in an axial thrust direction against the disc spring for smooth power transmission, while preventing it from being unnecessarily spaced from the starter-generator-side rotor.
[0037] In the above arrangement, the helical gear may have a thread spiral such that when the helical gear operates as a drive gear, the helical gear generates an axial thrust force for pressing the engine-side rotor against the starter-generator-side rotor.
[0038] With this arrangement, if the helical gear has such a thread spiral, the helical gear generates an axial thrust force to press the engine-side rotor against the starter-generator-side rotor when the helical gear functions as a drive gear. Therefore, the helical gear functions as a drive gear for engine start, with the engine-side rotor being pressed against the starter-generator-side rotor. The helical gear is prevented from moving in an axial thrust direction for power transmission without loss of operation, so that the engine can be started quickly without a feeling of slowness during starting. On the other hand, the helical gear functions as a driven gear for engine acceleration, with the engine-side rotor being pressed against the Belleville spring in an axial thrust direction away from the starter-generator-side rotor to absorb shock.
[0039] According to the present invention, the single arc spring is interposed between the first rotor and the second rotor, which are arranged coaxially with the central rotational axis and in facing relation to each other, to urge the first rotor and the second rotor to rotate in rotational directions opposite to each other, wherein the first urging protrusion protruding from the first rotor and the second urging protrusion protruding from the second rotor are arranged in relative positions on superimposed rotational trajectories, and the rubber member is interposed between the first urging protrusion and the second urging protrusion with gaps therebetween. When a torque load is applied to the first rotor and the second rotor, causing the first rotor and the second rotor to rotate relative to each other, the arc spring, which is highly elastically deformable and has a small elastic modulus, is initially elastically deformed under compression.When the torque load increases, the first compression protrusion and the second compression protrusion reduce the distance between them, pinching the rubber member inserted with gaps between them, whereupon the rubber member, which is deformable to a small extent and has a large elastic modulus, is elastically deformed under compression.
[0040] The arc spring operates under a low torque load and the rubber element operates under a high torque load to effectively absorb shocks depending on the high or low torque load for smooth power transmission at all times.
[0041] The arc spring comprises an arc-shaped coil spring. Although the single coil spring is sandwiched between the first rotor and the second rotor, it can be set to a large elastic operating angle (stroke) where it is elastically deformable to properly function its elasticity. Therefore, it is possible to provide a shock absorption mechanism with a simple structure and small size, consisting of a small number of parts. Fig. 1 is an overall side elevational view of a motorcycle incorporating an internal combustion engine including a power transmission device according to an embodiment of the present invention. Fig. 2 is a rear elevation view of the internal combustion engine. Fig. 3 is a left side elevational view of the internal combustion engine. Fig. 4 is a line IV-IV from Fig. 2 partial cross-sectional view taken. Fig. 5 is an enlarged view of a section of Fig. 4. Fig. 6 is an exploded perspective view of a front section power transmission device and a rear section power transmission device, the parts of which are shown spaced along a central axis of rotation. Fig. 7 is a partial perspective view of a crankshaft. Fig. 8 is an exploded perspective view of a portion of the front portion power transmission device. Fig. 9 is a perspective view of an engine-side rotor of the front portion power transmission device. Fig. 10 is a rear elevational view of the engine-side rotor of the front portion power transmission device. Fig. 11 is a front elevational view of a starter generator side rotor of the front section power transmission device. Fig. 12 is a line along the XII-XII of Fig. 11 taken cross-sectional view of the starter generator side rotor. Fig. 13 is an exploded perspective view of a portion of the front portion power transmission device with the parts assembled together. Fig. 14 is a cross-sectional view of the front portion power transmission device as seen from the front (toward the engine-side rotor) from a cutting plane between the engine-side rotor and the starter-generator-side rotor. Fig. 15 is a cross-sectional view of the front portion power transmission device under a small torque applied when the internal combustion engine is in normal operation. Fig. 16 is a cross-sectional view of the front portion power transmission device under a high torque load applied when the internal combustion engine is started, etc. Fig. 17 is an exploded perspective view of a portion of the rear portion power transmission device. Fig. 18 is a front elevational view of an engine-side rotor of the rear portion power transmission device. Fig. 19 is a line along the XIX-XIX from Fig. 18 taken cross-sectional view of the engine-side rotor. Fig. 20 is a rear cracked view of a rubber structural body. Fig. 21 is a view of the rubber structure body along the arrow XXI of Fig. 20 seen. Fig. 22 is a rear elevational view of a starter generator side rotor of the rear section power transmission device. Fig. 23 is a line along the XXIII-XXIII from Fig. 22 taken cross-sectional view of the starter generator side rotor. Fig. 24 is an exploded perspective view of a portion of the rear portion power transmission device with parts assembled together. Fig. 25 is a cross-sectional view of the rear portion power transmission device as viewed from the front (toward the engine-side rotor) from a cutting plane between the engine-side rotor and the starter-generator-side rotor. Fig. 26 is a cross-sectional view of the rear portion power transmission device under a low torque load applied when the internal combustion engine is in normal operation. Fig. 27 is a cross-sectional view of the rear portion power transmission device under a high torque load applied when the internal combustion engine is started, etc.
[0042] An embodiment of the present invention will be described hereinafter with reference to Fig. 1 to 27.
[0043] Fig. 1 is a side elevational view of a motorcycle 1 as a saddle-seat vehicle incorporating an internal combustion engine including a power transmission device according to the embodiment of the present invention.
[0044] In the present specification, front, rear, left, right, and similar directional terms are defined according to the normal orientations of the motorcycle 1 according to the present embodiment, including a forward direction along which the motorcycle 1 is moving forward in a straight line. In the drawings, reference symbols FR represent a forward direction, RR a reverse direction, LH a left direction, RH a right direction, and UP an upward direction.
[0045] The motorcycle 1 has a water-cooled 4-stroke internal combustion engine 20 with 6 horizontally opposed cylinders, which is oriented longitudinally of the motorcycle 1.
[0046] The motorcycle 1 includes a vehicle body frame 2 having a pair of left and right main frames 4 extending obliquely downward from a head pipe 3 on a front vehicle body portion, a swing frame 5 connected to the rear ends of the main frames 4, and a seat frame 6 having a front end connected to the swing frame 5 and extending rearward and obliquely upward from the front end and bent substantially horizontally and rearward.
[0047] A handlebar 9 is mounted on an upper portion of a steering stem 8, which is rotatably supported on the head tube 3. A pair of left and right front fork members 10 extend obliquely forward and downward from the steering stem 8. A front wheel 11 is rotatably supported on the lower ends of the front fork members 10.
[0048] A swing arm 12 has a front end pivotally supported on the swing frame 5 by a pivot shaft 13. Rear wheels 14 are supported in a cantilevered manner on the rear end of the swing arm 12, which is vertically pivotable.
[0049] The internal combustion engine 20 is suspended below the main frame 4. The internal combustion engine 20 has an output shaft 43 which extends rearwardly through the swing arm 12 into a gearbox (not shown) which is arranged centrally between the rear wheels, ie, left and right rear wheels 14, in order to transmit power of the internal combustion engine 20 to the rear wheels 14.
[0050] Fig. 2 is a rear elevational view of the 4-stroke internal combustion engine 20 having 6 horizontally opposed cylinders. Fig. 3 is a left side elevational view of the internal combustion engine 20.
[0051] The internal combustion engine 20 includes a crankcase 21 that houses a crankshaft 30 oriented in front and rear directions and rotatably supported in its upper half portion, and also houses a multi-stage transmission 40 in its lower half portion.
[0052] Referring to Fig. 2, the upper half portion of the crankcase 21 includes a left cylinder portion 21L and a right cylinder portion 21R projecting substantially horizontally to left and right sides from a central portion accommodating the crankshaft 30 therein.
[0053] The left cylinder section 12L and the right cylinder section 21R each have three cylinders defined therein arranged in the front and rear directions.
[0054] A left cylinder head 22L is stacked and fixed on a left side of the left cylinder section 21L, and a left cylinder head cover 23L covers a left side of the left cylinder head 22L.
[0055] Similarly, a right cylinder head 22R is stacked and fixed on a right side of the right cylinder section 21R, and a right cylinder head cover 23R covers a right side of the right cylinder head 22R.
[0056] Referring to Fig. 3, a front crankcase cover 24 is stacked and fixed to a front end surface of the crankcase 21. A rear crankcase cover 25 is stacked and fixed to a rear end surface of the crankcase 21.
[0057] Referring to Fig. 2, the transmission 40, which is housed in the lower half portion of the crankcase 21, comprises a main shaft 41 positioned below the crankshaft 30, and a countershaft 43 positioned to the right of the main shaft 41.
[0058] The main shaft 41 and the counter shaft 42 are oriented in the front and rear directions parallel to the crankshaft 30.
[0059] The output shaft 43 is positioned obliquely upwards from the counter shaft 42.
[0060] A dual clutch 45 is mounted on a rear end of the mainshaft 41, which extends rearward through the rear crankcase cover 25. The rear side of the dual clutch 45 is covered with a clutch cover 26.
[0061] As in Fig. 2 and Fig. 3, a starter generator 50 is mounted to the left and obliquely upwards of the double clutch 45 on a rear side of the rear crankcase cover 25.
[0062] The starter generator 50 is positioned behind the left cylinder section 21L of the internal combustion engine 20.
[0063] As in Fig. 4, the one along the line IV-IV on Fig. 2, a connecting rod 28 connects a piston 27, which is reciprocally movable in a cylinder bore defined in the left cylinder portion 21L, and the crankshaft 30, forming a crank mechanism.
[0064] The crankshaft 30 has a rear journal 30j rotatably supported by a metal bearing 21b on a bearing wall 21w of the left cylinder portion 21L, and includes a mounting flange 30f disposed rearward and adjacent to the journal 30j.
[0065] As in Fig. 7, the mounting flange 30f includes radial projections with six mounting holes 30fh defined therein, which are concentric with one another.
[0066] A large diameter helical gear 32 is fixedly mounted on the mounting flange 30f by six bolts 32b.
[0067] The large-diameter helical gear 32 is a backlash-eliminating gear assembly comprising a main gear 32m and a sub-gear 32s superimposed and coupled to each other with springs interposed therebetween.
[0068] The large diameter helical gear 32 is a helical gear having both the main gear 32m and the sub-gear 32s with a right-hand spiral thread (as seen in the front view, with rightward and upward spirally oriented threads) (see Fig. 6).
[0069] Referring to Fig. 4, a primary drive gear 31 adjacent to the large diameter helical gear 32 is coupled to the crankshaft 30 by toothing.
[0070] The primary drive gear 31, which is also a backlash eliminating gear, is held in mesh with a primary driven gear 46 fitted over the main shaft 41.
[0071] Two-section power transmission devices T F and T R , ie a front section power transmission device T F and a rear section power transmission device T R , are inserted one after the other between the crankshaft 30 of the internal combustion engine 20 and an input / output shaft 51 of the starter generator 50.
[0072] The front section power transmission device T F and the rear section power transmission device T R are arranged in an arrangement coaxial with the input / output shaft 51 of the starter generator 50.
[0073] The power transmission device according to the present invention is the front section power transmission device T F .
[0074] Referring to Fig. 4 and Fig. 5, the starter generator 50 includes a housing 50c having a circular opening 50h defined therein. The input / output shaft 51, rotatably supported by a bearing 52, projects forward through the circular opening 50h. The housing 50c has a plurality of axially arcuate engaging fingers 50cf concentrically arranged and projecting forward from a peripheral edge of the circular opening 50h in the housing in an axial direction of the input / output shaft 51.
[0075] As in Fig. 5, the rear crankcase cover 25, which is stacked on the rear end surface of the crankcase 21, includes a tubular portion 25a disposed in its upper left portion (see Fig. 2) and has an opening to the rear. The tubular portion 25a has an inner peripheral surface near its opening that is slightly cut off to form an engaging inner peripheral surface 25aa.
[0076] The axially arcuate engaging fingers 50cf, which protrude forward from the housing 50c of the starter generator 50, are fitted near its opening into the engaging inner peripheral surface 25aa in the tubular portion 25a of the rear crankcase cover 25. The starter generator 50 is thus positioned and mounted on the tubular portion 25a of the rear crankcase cover 25.
[0077] The axially arcuate engaging fingers 50cf projecting forward from the housing 50c of the starter generator 50 include three engaging fingers circumferentially spaced at equal intervals. One of the engaging fingers is positioned directly above a front end portion of the input / output shaft 51 and projects axially forward from the housing 50c in an axially arcuate covering relationship with an upper portion of the front end portion of the input / output shaft 51.
[0078] Heat generated by the starter generator 50 can be radiated through the spaces between the three engaging fingers 50cf. Raindrops are prevented from falling directly onto the input / output shaft 51 from above, and water is prevented from penetrating as far as the input / output shaft 51.
[0079] Referring to Fig. 5, the tubular portion 25a of the rear crankcase cover 25 is closed by a slightly tapered bearing wall 25b having an open rear portion and a front portion in the form of a hollow circular plate.
[0080] The bearing wall 25b comprises a tubular bearing section 25c arranged centrally thereon.
[0081] An intermediate shaft 60 is rotatably supported by a bearing 61 in the tubular bearing portion 25c of the bearing wall 25b.
[0082] The intermediate shaft 60, which is rotatably supported by the bearing 61 in the tubular bearing portion 25c, has a rear end rotatably supported by a bearing 62 in a bearing recess 21Lh defined in the left cylinder portion 21L of the crankcase 21.
[0083] The front section power transmission device T Fis held on the intermediate shaft 60 in front of the bearing wall 25b and is arranged between the bearing wall 25b and the left cylinder section 21L. The rear section power transmission device T R is held on the intermediate shaft 60 and the input / output shaft 51 within the tubular portion 25a of the rear crankcase cover 25 and is arranged between the bearing wall 25b and the left starter generator 50.
[0084] Next to Fig. 5 with reference to Fig. 6, which is an exploded perspective view of the front section power transmission device T F and the rear section power transmission device T Rwhose parts are shown as spaced along the central axis of rotation Lc, the intermediate shaft 60 has a flange 60f positioned in front of a journal 60j held by the bearing 61, which has a splined fitting portion 60sf formed near its front end and a splined fitting portion 60sr on its rear end portion.
[0085] The front section power transmission device T F according to the present invention will be described below.
[0086] The front section power transmission device T Fincludes an engine-side rotor (a first rotor) 71 to which power is initially transmitted from the engine 20, and a starter-generator-side rotor (a second rotor) 72 to which power is initially transmitted from the starter-generator 50. The engine-side rotor 71 and the starter-generator-side rotor 72, having disk shapes of substantially the same diameter, each have a first facing surface 71f and a second facing surface 72f that are close to and facing each other and are rotatably supported on the intermediate shaft 60.
[0087] As in Fig. 8 and Fig. As shown in Figure 10, the engine-side rotor 71 has a circular hole defined centrally therein. The first facing surface 71f, which has an annular shape, has an arcuate first receiving groove 71u defined therein, which receives one half of an arc spring 75 that is highly elastically deformable and has a small modulus of elasticity, and a pair of arcuate arc grooves 71v defined therein substantially concentrically with the first receiving groove 71u.
[0088] A pair of engine-side thrust protrusions 71p (first thrust protrusions) project rearward in each of the arcuate grooves 71v in the engine-side rotor 71, respectively, near the circumference toward opposite ends of the arcuate grooves 71v.
[0089] The engine-side thrust projections 71p are included in each of the arcuate grooves 71v.
[0090] Referring to Fig. 8 and Fig. 13, rubber elements 76 which are elastically deformable to a small extent and have a large modulus of elasticity are respectively mounted on the engine-side pressure projections 71p.
[0091] Each of the rubber members 76 is in the form of a flat columnar body having a sector shape when viewed axially, and has a fitting hole 76h defined axially therethrough which is slightly smaller and of a similar shape to the engine-side pressing projection 71p.
[0092] The rubber members 76 are mounted on the respective engine-side projections 71p, which are respectively fitted into the fitting holes 76h.
[0093] If the rubber elements 76, which are elastically deformable to a small extent and have a large modulus of elasticity, as in Fig. 13, are respectively mounted on the engine-side pressure projections 71p, the rubber elements 76 are fitted into the ends of the arcuate grooves 71v and are completely received in the arcuate grooves 71v.
[0094] One half of the arc spring 75, which is elastically deformable to a high degree and has a small modulus of elasticity, is received in the arc-shaped first receiving groove 71u.
[0095] The engine-side rotor 71, which is disk-shaped, has a machining clearance 71k (the stippled portion in Fig. 9) for the unbalance adjustment behind the arc-shaped first receiving groove 71u, which receives one half of the arc spring 75 therein.
[0096] Since the engine-side rotor 71 has the pair of arcuate grooves 71v transverse to the center rotation axis Lc opposite to the first receiving groove 71u, the engine-side rotor 71 tends to be unbalanced because it is heavier on the first receiving groove 71u side. The machining allowance 71k for unbalance adjustment behind the arcuate first receiving groove 71u is cut off to reduce the unbalance, allowing the engine-side rotor 71 to be balanced, thereby preventing itself from vibrating due to the unbalance.
[0097] As in Fig. 11 and Fig. 12, the disc-shaped starter-generator-side rotor 72 of the front section power transmission device T F a disc 72a and a tubular shaft 72s projecting forward from the center of the disc 72a.
[0098] The tubular shaft 72s has splines 72ss on a front end portion of its inner peripheral surface and an outer peripheral groove 72sv defined in its outer peripheral surface in the vicinity of its front end.
[0099] The disk 72a of the starter-generator-side rotor 72 has an arcuate second receiving groove 72u defined in the second facing surface 72f for receiving one half of the arc spring 75 therein.
[0100] The second receiving groove 72u has the same circumferential length as the first receiving groove 71u of the engine-side rotor 71.
[0101] Starter generator side pressing projections 72p (second pressing projections) project forward from the second facing surface 72f of the disk 72a at respective two locations circumferentially spaced from the circumferential center of the second receiving groove 72u so as to divide the circumference into approximately three equal lengths.
[0102] The disk 72a of the starter-generator-side rotor 72 has a machining clearance 72k (the stippled portions in Fig. 8 and Fig. 13) for the unbalance adjustment on its rear surface opposite to the arcuate second receiving groove 72u, which receives one half of the arc spring 75 transversely to the central rotation axis Lc.
[0103] Since the disk 72a of the starter-generator-side rotor 72 tends to be unbalanced because it is heavier on the side opposite to the second receiving groove 72u due to the second receiving groove 72u transverse to the center rotation axis Lc, the machining clearance 72k for unbalance adjustment is arranged opposite to the second receiving groove 72u and cut off to reduce the unbalance, which allows the starter-generator-side rotor 72 to be balanced to thereby prevent itself from vibrating due to the unbalance.
[0104] As in Fig. 13, the first receiving groove 71u in the engine-side rotor 71 and the second receiving groove 72u in the starter-generator-side rotor 72, which receive the arc spring 75 therein, are brought into a facing relationship, causing the first facing surface 71f and the second facing surface 72f to oppose each other, and the starter-generator-side pressing projections 72p protrude from the circumference toward nearly central portions of the arcuate surfaces of the second facing surface 72f, which correspond to the arcuate grooves 71v in the engine-side rotor 71.
[0105] Specifically, the starter generator side pressing protrusions 72p are arranged in respective positions substantially corresponding to middle portions of the arcuate grooves 71v between the engine side pressing protrusions 71p near the circumferentially opposite ends of the arcuate grooves 71v.
[0106] Therefore, when the first receiving groove 71u and the second receiving groove 72u, which receive the arc spring 75 therein, are brought together in facing relation with the engine-side rotor 71 and the starter-generator-side rotor 72 mounted closely to each other, no relative torque load is applied to the engine-side rotor 71 and the starter-generator-side rotor 72. As shown in Fig. As shown in Figure 14, the starter-generator-side thrust protrusions 72p are each inserted into arcuate grooves 71v in the engine-side rotor 71 and positioned substantially centrally between the paired engine-side thrust protrusions 71p. The engine-side thrust protrusions 71p and the starter-generator-side thrust protrusions 72p are arranged in relative positions on superimposed rotation trajectories.
[0107] Fig. 14 is a cross-sectional view of the front portion power transmission device T FViewed from a sectional plane between the first facing surface 71f of the engine-side rotor 71 and the second facing surface 72f of the starter-generator-side rotor 72 from the front (toward the engine-side rotor 71), the engine-side rotor 71 and the starter-generator-side rotor 72 are mounted closely to each other. The starter-generator-side thrust protrusions 72p protruding from the second facing surface 72f of the starter-generator-side rotor 72 are shown in cross section.
[0108] If, as in Fig. 14, no relative torque load is applied to the engine-side rotor 71 and the starter-generator-side rotor 72, the starter-generator-side protrusions 72p are positioned substantially centrally between the paired rubber members 76 mounted on the respective paired engine-side pressing protrusions 71p. More specifically, an angle θa of each of the starter-generator-side pressing protrusions 72p to one of the corresponding paired rubber members 76 spaced therefrom in the rotational direction is shown by the arrow in Fig. 14, smaller than an angle θb from the starter-generator-side pressing projection 72p to the other rubber member 76 spaced in the direction opposite to the rotational direction thereof.
[0109] In other words, when no relative torque load is applied to the engine-side rotor 71 and the starter-generator-side rotor 72, the starter-generator-side pressing projections 72p are positioned closer to these rubber members 76, which are spaced apart from them in the rotational direction.
[0110] Referring to Fig. 5 and Fig. 6, for assembling the engine-side rotor 71 and the starter-generator-side rotor 72 so as to be rotatably supported on the intermediate shaft 60, a small-diameter helical gear 33 is held against a front side of the engine-side rotor 71 with the rubber members 76 mounted on the engine-side pressing projections 71p, and mounting bolts 34 are respectively inserted from the rear through circumferentially spaced five mounting holes defined in an inner peripheral portion of the engine-side rotor 71 and screwed into threaded holes in the small-diameter helical gear 33, whereby the small-diameter helical gear 33 is integrally mounted on the engine-side rotor 71.
[0111] The small diameter helical gear 33 is a helical gear with a left-hand spiral thread and is held in mesh with the large diameter helical gear 32 fixed to the crankshaft 30.
[0112] The left-hand thread spiral refers to threads that, when viewed in front view, are essentially oriented spirally to the left and upwards.
[0113] The tubular shaft 72s of the disc-shaped starter-generator-side rotor 72 is inserted from the rear through axial center holes in the engine-side rotor 71 and the small-diameter helical gear 33, which are integrally combined with each other. The disc 72a is superimposed on the engine-side rotor 71 with the arc spring 75 interposed therebetween, and the second facing surface 72f of the disc-shaped starter-generator-side rotor 72 is brought into close contact with the first facing surface 71f of the engine-side rotor 71.
[0114] The engine-side rotor 71 and the small-diameter helical gear 33 are slidably and rotatably supported on the tubular shaft 72s of the disc-shaped starter-generator-side rotor 72.
[0115] A disc spring 35, a collar 36 and a stopper 37 are sequentially arranged in the order mentioned on a portion of the tubular shaft 72s of the disc-shaped starter generator side rotor 72, which protrudes forward from the engine side rotor 71.
[0116] Specifically, the disc spring 35 is interposed between the collar 36, which is prevented from moving forward by the stopper 37 fitted into the outer circumferential groove 72sv defined in the tubular shaft 72s, and the small-diameter helical gear 33. The engine-side rotor 71, together with the small-diameter helical gear 33, is normally urged by the disc spring 35, so that they move toward the disc-shaped starter-generator-side rotor 72.
[0117] The stopper 37 fitted into the outer peripheral groove 72sv is covered by a removal protection bracket 38 which is prevented from moving by a retaining ring 39.
[0118] The intermediate shaft 60 is inserted from the rear into the tubular shaft 72s of the disc-shaped starter-generator-side rotor 72 of the thus assembled assembly of the engine-side rotor 71 and the starter-generator-side rotor 72. When the intermediate shaft 60 is inserted until its flange 60f abuts against the rear end of the tubular shaft 72s, the splined fitting portion 60sf near the front end of the intermediate shaft 60 is brought into fitting relation with the splines 72ss on the front end portion of the inner peripheral surface of the tubular shaft 72s.
[0119] Therefore, the starter generator side rotor 72 and the intermediate shaft 60 are rotatable in unison with each other.
[0120] Referring to Fig. 5, the front end of the intermediate shaft 60, on which the assembly of the engine-side rotor 71 and the starter-generator-side rotor 72 is supported, is rotatably supported by the bearing 62 in the bearing recess 21Lh defined in the left cylinder portion 21L. A portion of the intermediate shaft 60 forward of the flange 60f is rotatably supported by the bearing 61 in the tubular bearing portion 25c of the bearing wall 25b of the rear crankcase cover 25. The small-diameter helical gear 33, which is integrally combined with the engine-side rotor 71, is held in mesh with the large-diameter helical gear 32 fixed to the crankshaft 30.
[0121] The bearing 61, which is fitted from its front side into the tubular bearing portion 25c of the bearing wall 25b, has an outer race which is pressed from its front side by a pressure plate 63 which is fixed to the bearing wall 25b by bolts 64.
[0122] In this way, the engine-side rotor 71 and the starter-generator-side rotor 72 of the front-section power transmission device T F , as in Fig. 5, held on the intermediate shaft 60 and assembled.
[0123] Power is transmitted between the engine-side rotor 71 and the crankshaft 30 of the engine 20 through the small-diameter helical gear 33 and the large-diameter helical gear 32, which are held in mesh with each other.
[0124] Power is transmitted between the intermediate shaft 60, which rotates in unison with the starter generator side rotor 72, and the input / output shaft 51 of the starter generator 50 through the rear section power transmission device T R , which will be described later.
[0125] The single arc spring 75, which is elastically deformable to a high degree and has a small modulus of elasticity, and the four rubber members 76, which are elastically deformable to a small degree and have a large modulus of elasticity, which urge the engine-side rotor 71 and the starter-generator-side rotor 72 in their relative rotation directions, are inserted between the engine-side rotor 71 and the starter-generator-side rotor 72.
[0126] While no relative torque load is applied to the engine-side rotor 71 and the starter-generator-side rotor 72, the first receiving groove 71u in the engine-side rotor 71 and the second receiving groove 72u in the starter-generator-side rotor 72, which receive the arcuate spring 75 therein, are aligned with each other, and the starter-generator-side pressing projections 72p are, as shown in Fig. 14, arranged substantially centrally between the rubber elements 76 mounted on the paired engine-side pressure projections 71p.
[0127] Under a small torque load applied to the engine-side rotor 71 and the starter-generator-side rotor 72, which causes them to rotate with a small speed difference when the engine 20 is in normal operation, the arc spring 75, as shown in Fig. 15, compressively deforms, and the rubber members 76 mounted on these engine-side compression protrusions 71p positioned on the opposite side to the rotational direction come closer to the starter-generator-side compression protrusions 72p. Consequently, the arc spring 75, which is highly elastically deformable and has a small elastic modulus, absorbs a smaller shock for smooth power transmission.
[0128] Under a high torque applied to the engine-side rotor 71 and the starter-generator-side rotor 72, which causes them to rotate with a large speed difference when the engine 20 is operated for rapid acceleration, the arc spring 75 is released from the Fig. 15, the rubber members 76 mounted on these engine-side pressing protrusions 71p positioned on the opposite side to the rotation direction are brought into contact with the starter-generator-side pressing protrusions 72p and sandwiched between the starter-generator-side pressing protrusions 72p and the engine-side pressing protrusions 71p. Consequently, the rubber members 76, which are elastically deformable to a small extent and have a large elastic modulus, are compressively deformed and absorb a larger shock.
[0129] When the internal combustion engine 20 is started or stalled, a large torque load is applied to the engine-side rotor 71 and the starter-generator-side rotor 72 through the intermediate shaft 60, causing them to rotate at a large speed difference. As shown in Fig. As shown in Figure 16, the arc spring 75 is deformed from the compressive state, and the starter-generator-side compression protrusions 72p approach and contact the rubber members 76 mounted on the engine-side compression protrusions 71p positioned on the same side of the rotational direction. The rubber members 76 are then sandwiched between the starter-generator-side compression protrusions 72p and the engine-side compression protrusions 71p. Consequently, the rubber members 76, which are elastically deformable to a small extent and have a large elastic modulus, are compressively deformed, absorbing a greater shock.
[0130] The rear section power transmission device T R is described below.
[0131] As in Fig. 5, the front section power transmission device T Fan engine-side rotor 81 to which power is initially transmitted from the engine 20, and a starter-generator-side rotor 82 to which power is initially directly transmitted from the starter-generator 50. The engine-side rotor 81 and the starter-generator-side rotor 82 are arranged in a facing relationship.
[0132] The engine-side rotor 81 is integrally supported on the intermediate shaft 60. The starter-generator-side rotor 82 is integrally supported on the input / output shaft 51 of the starter-generator 50.
[0133] Referring to Fig. 17 to 19, the engine-side rotor 81 includes a first flat tubular portion 81a, a bottom wall 81b closing a front opening of the tubular portion 81a, and a tubular shaft 81s projecting forward from the center of the bottom wall 81b.
[0134] The tubular shaft 81s has splines 81ss on a front end portion of its inner peripheral surface.
[0135] Engine-side pressing projections 81p at predetermined four positions of a lower surface of the lower wall 81b protrude from an inner peripheral surface of the tubular portion 81a as radially oriented plates.
[0136] The engine-side pressing protrusions 81p include two closely spaced engine-side pressing protrusions 81p and other two closely spaced engine-side pressing protrusions 81p positioned transversely to the center rotation axis Lc in symmetrical relationship to the first-mentioned closely spaced engine-side pressing protrusions 81p.
[0137] The radially oriented engine-side projections 81p include respective projections 81pp projecting axially rearward from their sides near the center rotation axis Lc.
[0138] The projections 81pp have projecting end surfaces flush with an open end surface of the tubular portion 81a. The engine-side pressing projections 81p have respective recesses 81d defined between the projections 81pp and the tubular portion 81a.
[0139] Between the closely spaced engine-side thrust protrusions 81p of the engine-side rotor 81, ridges 81t are arranged, which are raised on outer peripheral portions of the sector wall surfaces of the bottom wall 81b. The ridges 81t have tapered surfaces on their end surfaces, except for surfaces near the engine-side thrust protrusions 81p on both sides thereof.
[0140] The webs 81t are spaced on both sides by gaps from the engine-side pressure projections 81p.
[0141] A rubber structural body 85A or a rubber structural body 85B is mounted and held on each of the engine-side pressing projections 81p of the engine-side rotor 81.
[0142] The rubber structural body 85A and the rubber structural body 85B each include a soft rubber member 86 that is highly elastically deformable and has a small elastic modulus, and a hard rubber member 87 that is slightly elastically deformable and has a large elastic modulus. The soft rubber member 86 and the hard rubber member 87 are integrally formed with each other. The rubber structural body 85A and the rubber structural body 85B have symmetrical shapes and structures.
[0143] The rubber structure body 85A will be described below with reference to Fig. 20 and Fig. 21 described.
[0144] Fig. 20 is a rear crack view of the rubber structure body, and Fig. 21 is a line drawn along arrow XXI from Fig. 20 seen view of the rubber structure body.
[0145] The soft rubber element 86 (the thinly dotted sections in Fig. 20 and Fig. 21) of the rubber structural body 85A comprises a pair of circumferentially spaced radially elongated end side portions 86a and 86b and a connecting rib 86c which connects the end side portions 86a and 86b axially along the central rotational axis Lc in Fig. 20 (as seen in the rear elevation). The soft rubber element 86 has a sector shape when viewed axially along the central rotation axis Lc.
[0146] The connecting rib 86c connects the end side portions 86a and 86b on their radially outer sides, except for their sides closer to the central rotation axis Lc.
[0147] In addition, the connecting rib 86c is thinner than the end side portions 86a and 86b along the axial directions of the center rotation axis Lc (see Fig. 21).
[0148] The end side portions 86a and 86b of the soft rubber member 86 have respective inner end projections 86ai and 86bi projecting from their inner ends near the center rotation axis in the rotation direction, and also have respective outer end projections 86ao and 86bo projecting from their radially outer ends in the rotation direction.
[0149] The hard rubber element 87 (densely dotted sections in Fig. 20 and Fig. 21) of the rubber structure body 85A has a sector shape which expands to a small degree as viewed axially along the center rotation axis Lc.
[0150] The hard rubber member 87 is circumferentially positioned adjacent to the end side portion 86b of the end side portions 86a and 86b of the soft rubber member 86. The end side portion 86b and the hard rubber member 87 are connected to each other by a rubber connecting rib 87c near their outer ends.
[0151] The rubber connecting rib 87c connects the end side portion 86b and the hard rubber member 87 at an axially rear position (see Fig. 21).
[0152] As in Fig. 17, the other rubber structural body 85B is formed in a mirror-symmetrical relationship with the rubber structural body 85A.
[0153] Therefore, the parts of the soft rubber member 86 and the hard rubber member 87 of the rubber structural body 85B are designated by reference numerals identical to those of the rubber structural body 85A.
[0154] As in Fig. 24, the rubber structural bodies 85A and the rubber structural bodies 85B are each mounted on closely spaced engine-side pressing projections 81p projecting inward from the tubular portion 81a of the engine-side rotor 81.
[0155] Referring to Fig. 17 and Fig. 24, the end side portions 86b of the soft rubber members 86 and the hard rubber members 87, which are adjacent to each other and connected by the rubber connecting ribs 87c, respectively clamp the engine-side pressing protrusions 81p. The rubber structural bodies 85A and the rubber structural bodies 85B are respectively mounted on the closely spaced engine-side pressing protrusions 81p under the clamping pressure due to the elastic forces from the rubber connecting ribs 87c.
[0156] Therefore, the rubber structural bodies 85A and the rubber structural bodies 85B, as shown in Fig. 24, each reliably attached to the engine-side pressure projections 81p and mounted thereon.
[0157] The rubber connecting ribs 87c are fitted into the respective recesses 81d defined between the projections 81pp of the engine-side pressing projections 81p and the tubular portion 81a. The projections 81pp are clamped between the end side portions 86b of the soft rubber members 86 and the hard rubber members 87.
[0158] The rubber structural bodies 85A and the rubber structural bodies 85B are assembled in position so that the hard rubber members 87 are positioned inside the closely spaced engine-side pressing projections 81p.
[0159] The hard rubber members 87 are fitted into gaps between the lands 81t raised between the closely spaced engine-side pressing projections 81p and the engine-side pressing projections 81p.
[0160] As in Fig. 22, Fig. 23, and Fig. 24, the starter-generator-side rotor 82 of the rear section power transmission device T R a disk 82a having a tubular projection 82b centrally disposed thereon about the central rotational axis Lc, and four plate-like starter-generator-side thrust projections 82p circumferentially spaced at equal intervals and projecting forwardly from front surface portions of the disk 82a extending radially outwardly from the tubular projection 82b.
[0161] The tubular extension 82b has serrations 82bs on its inner peripheral surface.
[0162] Each of the starter-generator-side pressing protrusions 82p has the shape of a substantially rectangular plate. Of the starter-generator-side pressing protrusions 82p, a pair of starter-generator-side pressing protrusions 82p that are symmetrical with respect to the center rotation axis Lc have respective front outer peripheral end portions cut at an angle to slopes 82pt.
[0163] The bevels 82pt of the starter-generator-side pressure projections 82p each correspond to the webs 81t of the engine-side rotor 81, while being free of the webs 81t in order to avoid physical interference therewith.
[0164] Referring to Fig. 5, the tubular shaft 81s of the engine-side rotor 81 is fitted by the splines over the rear end portion projecting rearward from the bearing 61 of the intermediate shaft 60 rotatably supported by the bearing 61 in the tubular bearing portion 25c of the rear crankcase cover 25, with the rubber structural body 85A and the rubber structural body 85B mounted on the engine-side pressing projections 81p.
[0165] A sealing ring 65 is inserted between the tubular shaft 81s and the tubular bearing portion 25c.
[0166] Then, a mounting bolt 66 is screwed from the rear into a threaded hole 60h opened in a rear end face of the intermediate shaft 60 with a washer 67 interposed therebetween, whereby the tubular shaft 81s of the engine-side rotor 81 is fixed together with an inner race 61 against the flange 60f of the intermediate shaft 60. The engine-side rotor 81 is thus fixed to the intermediate shaft 60 and held thereon for rotation in unison therewith.
[0167] Referring to Fig. 5 and Fig. 6, the tubular boss 82b of the starter-generator-side rotor 82 is fitted through the splines over the front end portion of the input / output shaft 51 projecting from the circular opening 50h in the housing 50c of the starter-generator 50.
[0168] A mounting bolt 68 is screwed from the rear into a threaded hole 51h opened in a front end surface of the input / output shaft 51, with a washer 69 interposed therebetween, and the tubular boss 82b is fixed to the front end portion of the input / output shaft 51. The starter-generator-side rotor 82 is thus fixed to the input / output shaft 51 and held thereon for rotation in unison therewith.
[0169] With the starter generator side rotor 82 mounted on the input / output shaft 51 of the starter generator 50, the starter generator 50 is fixed to the tubular portion 25a of the rear crankcase cover 25.
[0170] At this time, the engaging fingers 50cf projecting forward from the housing 50c of the starter generator 50 are fitted near its opening against the inner engaging peripheral surface 25aa of the tubular portion 25a of the rear crankcase cover 25, thereby positioning the starter generator 50 such that the input / output shaft 51 is coaxially aligned with the intermediate shaft 60.
[0171] For fastening the starter generator 50 to the tubular portion 25a of the rear crankcase cover 25, it is necessary to combine the starter generator side rotor 82 with the engine side rotor 81 at a predetermined relative rotation angle.
[0172] Specifically, the starter-generator-side rotor 82 is combined with the engine-side rotor 81 at such a relative rotation angle that the starter-generator-side pressing protrusions 82p having the slopes 82pt of the starter-generator-side rotor 82 are sandwiched between the hard rubber members 87 of the rubber structural bodies 85A and the hard rubber members 87 of the rubber structural bodies 85B disposed inside the closely spaced engine-side pressing protrusions 81p of the engine-side rotor 81.
[0173] Fig. 25 is a cross-sectional view of the rear portion power transmission device T RViewed from a sectional plane between the disc 82a of the engine-side rotor 81 and the tubular portion 81a of the starter-generator-side rotor 72 from the front (toward the engine-side rotor 71), the engine-side rotor 81 and the starter-generator-side rotor 82 are combined. The starter-generator-side thrust projections 82p protruding from the disc 82a of the engine-side rotor 81 and the tubular extension 82b are shown in cross section.
[0174] Referring to Fig. 25, the starter-generator-side thrust projections 82p with the slopes 82pt of the engine-side rotor 81 are inserted between the hard rubber members 87 of the rubber structural bodies 85A and the hard rubber members 87 of the rubber structural bodies 85B with gaps therebetween without physically interfering with the webs 81t of the engine-side rotor 81.
[0175] The starter-generator-side thrust projections 82p without slants of the engine-side rotor 81 are inserted between the end side portions 86a of the soft rubber members 86 of the rubber structural bodies 85A and the end side portions 86a of the soft rubber members 86 of the rubber structural bodies 85B without gaps therebetween.
[0176] In other words, the starter generator side pressure projections 82p are clamped between the end side portions 86a of the soft rubber members 86 without bevels 82pt.
[0177] Thus, when the starter-generator-side rotor 82 is combined with the engine-side rotor 81, the engine-side pressure protrusions 81p and the starter-generator-side pressure protrusions 82p are arranged in relative positions superimposed on rotation trajectories.
[0178] Fig. 25 illustrates a state where no relative torque load is applied to the engine-side rotor 81 and the starter-generator-side rotor 82. The starter-generator-side pressing protrusions 82p having the slopes 82pt are positioned between the hard rubber members 87 with gaps on both sides thereof, while the starter-generator-side pressing protrusions 82p without slopes are positioned between the end side portions 86a of the soft rubber members 86 without a gap therebetween.
[0179] Under a small torque load applied by the intermediate shaft 60 to the engine-side rotor 81 and the starter-generator-side rotor 82, which causes them to rotate with a small speed difference when the engine 20 is in normal operation, the engine-side pressing projections 81p and the starter-generator-side pressing projections 82p press without slants, as shown in Fig. 26, the soft rubber members 86 of the rubber structural bodies 85A compressively deform and bring the hard rubber members 87 of the rubber structural bodies 85B closer to the starter-generator-side protrusions 82p with the slopes. Therefore, the soft rubber members 86, which are highly elastically deformable and have a small elastic modulus, absorb a smaller shock for smooth power transmission.
[0180] Under a high torque load applied to the engine-side rotor 81 and the starter-generator-side rotor 82, which causes them to rotate with a large speed difference when the engine 20 is operated for rapid acceleration, the soft rubber members 86 of the rubber structure bodies 85A are made of the Fig. 26, the hard rubber members 87 of the rubber structural bodies 85B are further compressively deformed, and the hard rubber members 87 of the rubber structural bodies 85B contact the starter-generator-side compression projections 82p having the slopes 82pt. The hard rubber members 87 of the rubber structural bodies 85B are sandwiched between the engine-side compression projections 81p and the starter-generator-side compression projections 82p having the slopes. The hard rubber members 87, which are elastically deformable to a small extent and have a large elastic modulus, are thus compressively deformed to absorb a larger shock.
[0181] When the internal combustion engine 20 is started or stalled, a large torque load is applied to the engine-side rotor 81 and the starter-generator-side rotor 82, causing them to rotate with a large speed difference. As shown in Fig. As shown in Figure 27, the starter-generator-side pressing protrusions 82p without slopes and the engine-side pressing protrusions 81p press the soft rubber members 86 of the rubber structural body 85B therebetween and compressively deform them. The starter-generator-side pressing protrusions 82p with the slopes 82p approach and contact the hard rubber members 87 of the rubber structural bodies 85A. The hard rubber members 87 of the rubber structural bodies 85A are sandwiched between the engine-side pressing protrusions 81p and the starter-generator-side pressing protrusions 82p. The rubber members 76, which are elastically deformable to a small extent and have a large elastic modulus, are thus deformed to absorb a larger shock.
[0182] As described above, the power transmission device according to the present embodiment includes the two-section power transmission devices T F and T R, each having a shock absorbing function, ie the front section power transmission device T F and the rear section power transmission device T R , which are arranged in series between the crankshaft 30 of the internal combustion engine 20 and the input / output shaft 51 of the starter generator 50 with the intermediate shaft 60 interposed therebetween. Therefore, the power transmission device can reliably absorb shocks generated by torque loads between the internal combustion engine 20 and the starter generator 50 for smooth power transmission.
[0183] The front section power transmission device T F according to the embodiment of the present invention described in detail above, offers the following results: The single arc spring 75 is interposed between the engine-side rotor (the first rotor) 71 and the starter-generator-side rotor (the second rotor) 72, which are arranged coaxially with the central rotational axis Lc and in a facing relationship, to urge the engine-side rotor 71 and the starter-generator-side rotor 72 in opposite rotational directions, and the engine-side pressing protrusions (the first pressing protrusions) 71p protruding from the engine-side rotor 71 and the starter-generator-side pressing protrusions (the second pressing protrusions) 72p protruding from the starter-generator-side rotor 72 are arranged in relative positions on superimposed rotation trajectories. Since the rubber members 76, as shown in Fig. 14, with gaps between the engine-side pressure projections 71p and the starter-generator-side pressure projections 72p, the arc spring 75, which is elastically deformable to a high degree and has a small modulus of elasticity, is elastically deformed under compression (see Fig. 15) when a torque load is applied to the engine-side rotor 71 and the starter-generator-side rotor 72, causing them to rotate relative to each other. As the torque load increases, the first pressing protrusions and the second pressing protrusions further reduce the gaps therebetween, pinching the rubber members 76 that have been inserted with gaps therebetween, whereupon the soft rubber members 76, which are elastically deformable to a small extent and have a large elastic modulus, are elastically deformed under compression (see Fig. 16).
[0184] While the torque load is low, the arc spring 75, which is elastically deformable to a high degree and has a small modulus of elasticity, absorbs as in Fig. 15, effectively shocks in a large stroke.
[0185] As the torque load increases, the soft rubber members 76, which are elastically deformable to a small extent and have a large modulus of elasticity, are elastically deformed under compression. As shown in Fig. 16, the soft rubber elements 76 effectively absorb a larger shock for smooth power transmission.
[0186] In other words, the arc spring 75 works under a low torque load and the rubber elements 75 work under a high torque load to effectively absorb shocks depending on the high or low torque load for smooth power transmission at all times.
[0187] As in Fig. As shown in Figure 14, the arc spring 75 comprises an arc-shaped coil spring. Although the arc spring 75, which is interposed between the engine-side rotor 71 and the starter-generator-side rotor 72, is single, it can be set to a large elastic operating angle (stroke) in which it is elastically deformable to properly function its elasticity. Therefore, it is possible to provide a shock absorbing mechanism with a simple structure and small size, consisting of a small number of parts.
[0188] Since in this arrangement the bow spring 75, as shown in Fig. 13, is inserted between the engine-side rotor 71 and the starter-generator-side rotor 72, the respective halves being received in the first receiving groove 71u and the second receiving groove 72u, respectively, a compression structure of the arc spring 75 for urging the engine-side rotor 71 and the starter-generator-side rotor 72 in opposite rotation directions and a holding structure of the arc spring can be composed of a minimum number of simple parts.
[0189] In other words, depending on the applied torque load, suitable rubber elements act to effectively absorb the shock for smooth power transmission at all times.
[0190] Since the rubber elements 76, as in Fig. 13, are fitted over the engine-side pressing projections 71p, the rubber members 76 are simply mounted on the engine-side pressing projections 71p without using special mounting members and are firmly held between the engine-side pressing projections 71p and the starter-generator-side pressing projections 72p.
[0191] On the engine-side rotor 71, the first receiving groove 71u is open in the first facing surface 71f, and the arcuate grooves 71v defined therein, which are substantially concentric with the first receiving groove 71u, are open in the first facing surface 71f. The paired engine-side pressing protrusions 71p are arranged in each of the arcuate grooves 71v near both ends thereof in the circumferential direction, and the rubber members 76 are respectively mounted on the paired engine-side pressing protrusions 71p. On the starter-generator-side rotor 72, the second receiving groove 72u is open in the second facing surface 72f, and the starter-generator-side pressing projections 72p protrude from the circumferentially nearly central portions of the arcuate surfaces of the second facing surface 72f, which correspond to the arcuate grooves 71v in the second facing surface 72f.Therefore, the starter-generator-side pressing projections 72p of the starter-generator-side rotor 72 are inserted between the rubber members 76 each fitted over the paired engine-side pressing projections 71p of the engine-side rotor 71 (see FIG. Fig. 14). Under a high torque load, as in Fig. As shown in Fig. 16, each of the starter-generator-side pressing protrusions 72p and each of the paired engine-side pressing protrusions 71p clamps one of the rubber members 76. The rubber members, which are elastically deformable to a small extent and have a large elastic modulus, are elastically deformed under compression and effectively absorb a large shock for smooth power transmission.
[0192] Since referring to Fig. 13, the rubber members 76 fitted over the engine-side pressing protrusions 71p are received in the arcuate grooves 71v, the rubber members 76 do not protrude outward from the first facing surface 71f. Upon relative rotation of the engine-side rotor 71 and the starter-generator-side rotor 72, the circumferential end edges of the second receiving groove 72u in the starter-generator-side rotor 72 do not physically interfere with the rubber members 76, and thus do not damage the rubber members 76 and impair their durability.
[0193] Since the engine-side rotor 71 having the disk shape has the pair of arcuate grooves 71v which are transverse to the central rotational axis Lc opposite to the first receiving groove 71u, the engine-side rotor 71 tends to be unbalanced because it is heavier on the side of the first receiving groove 71u. As shown in Fig. 9, the machining clearance 71k for unbalance adjustment behind the first receiving groove 71u is cut off to reduce the unbalance, which makes the engine-side rotor 71 balanced to thereby prevent the rotor itself from vibrating due to the unbalance.
[0194] Since the second rotor 72 having the disk shape tends to be unbalanced because it is heavier on the side transverse to the central rotational axis Lc opposite to the second receiving groove 72u due to the second receiving groove 72u, the machining allowance 72k for the unbalance adjustment is as shown in Fig. 8 and Fig. 13, is arranged opposite to the second receiving groove 72u and cut off to reduce the unbalance, which makes the starter generator side rotor 72 balanced to thereby prevent it from vibrating itself due to the unbalance.
[0195] Under a small torque load applied to the engine-side rotor 71 and the starter-generator-side rotor 72, which causes them to rotate with a small speed difference when the engine 20 is in normal operation, as shown in Fig. 15, the arc spring 75, which is highly elastically deformable and has a small modulus of elasticity, compressively deforms and absorbs a smaller shock for smooth power transmission.
[0196] On the other hand, under a high torque load applied to the engine-side rotor 71 and the starter-generator-side rotor 72, which causes them to rotate with a large speed difference when the engine is started, stalled, or operated for rapid acceleration, as shown in Fig. 16, the rubber elements 76, which are elastically deformable to a small extent and have a large modulus of elasticity, as well as the arc spring 75, compressively deform and absorb a larger shock.
[0197] If, as in Fig. 14, there is no speed difference between the engine-side rotor and the starter-generator-side rotor, the angle θa of each of the starter-generator-side projections 72p to one of the rubber members 76 spaced apart in the direction of rotation thereof is as shown by the arrow in Fig. 14, is smaller than the angle θb from the starter-generator-side pressing projection 72p to the other rubber member 76 spaced therefrom in the direction opposite to the direction of rotation.
[0198] In other words, when no relative torque load is applied to the engine-side rotor 71 and the starter-generator-side rotor 72, the starter-generator-side thrust protrusions 72p are positioned closer to the rubber members 76 spaced apart in the rotational direction. Consequently, the starter-generator-side thrust protrusions 72 act on the rubber members 76 spaced apart in the rotational direction for an earlier engine start, resulting in a reduced operating loss for early engine start (see Fig. 16).
[0199] When the motorcycle is running normally, the arc spring 75 is compressed to a high degree and absorbs a small shock for smooth power transmission until the starter-generator-side thrust protrusions 72p act on the other rubber members 76 positioned on the opposite side of the starter-generator-side thrust protrusions 72p in the rotational direction. Noises such as gear backlash noise can be limited in this way (see Fig. 15).
[0200] Referring to Fig. 5 and Fig. 6, the engine-side rotor 71 is fixed to the small-diameter helical gear 33, which meshes with the large-diameter helical gear 32 slidably supported on the rotor shaft 72s of the starter-generator-side rotor 72. The disc spring 35 is interposed between the collar 35, which is prevented from sliding by the stopper 36, which meshes with the small-diameter helical gear 33 on the outer periphery of the rotor shaft 72s on the opposite side of the engine-side rotor 71.Therefore, the engine-side rotor 71 is normally urged by the disc spring 35 to move toward the disc-shaped starter-generator-side rotor 72, and is allowed to move together with the small-diameter helical gear 33 in an axial thrust direction against the disc spring 35 for smooth power transmission while being prevented from being unnecessarily spaced from the starter-generator-side rotor 72.
[0201] Referring to the meshing engagement between the small diameter helical gear 33 and the large diameter helical gear 32 and the direction indicated by the arrows in Fig.6, the small-diameter helical gear 33 has a left-hand thread spiral (with threads oriented spirally to the left as viewed in front elevation). Therefore, for engine start, the helical gears function as drive gears, pressing the engine-side rotor 71 against the starter-generator-side rotor 72. The helical gears are prevented from moving in an axial thrust direction for power transmission without loss of operation, so that the engine can be started quickly without a feeling of slowness during starting. On the other hand, for engine acceleration, the helical gears function as driven gears, pressing the engine-side rotor 71 against the Belleville spring in an axial thrust direction away from the starter-generator-side rotor 72 to absorb shock.
[0202] While the rear section power transmission device T RAccording to the embodiment of the present invention has already been described here, the present invention is not limited to the above embodiment, but can be implemented in various forms within the scope of the invention.
[0203] For example, the vehicle according to the present invention is not limited to the saddle-seat motorcycle 1 according to the embodiment, but may be any of various saddle-seat vehicles, including scooter vehicles, three-wheeled vehicles, and quadricycles, etc., as long as they incorporate the requirements of claim 1. List of reference symbols: 1 motorcycle, 2 vehicle body frames, 3 head pipe, 4 main frames, 5 swivel frames, 6 seat frames, 7, 8 steering stem, 9 handlebar, 10 front fork element, 11 front wheel, 12 swingarm, 13 swivel shaft, 14 rear wheel, 20 internal combustion engine, 21 crankcase, 21L Left cylinder section, 21R Right cylinder section, 21P oil pan, 21Wr Rear locking rib, 21Wp pump locking rib, 22L Left cylinder head, 22R Right cylinder head, 23L Left cylinder head cover, 23R Right cylinder head cover, 24 Front clutch housing cover, 25 Rear clutch housing cover, 26 clutch cover, 27 pistons, 28 connecting rod, 30 crankshaft, 31 Primary drive gear, 32 large diameter helical gear, 33 small diameter helical gear, 34 mounting bolts, 35 disc spring, 36 cuff, 37 attack, 38 bracket, 39 retaining ring, 40 gearboxes, 41 main shaft, 42 countershaft, 43 output shaft, 44, 45 double clutch, 46 Primary driven gear, 50 starter generator, 51 Input / output shaft, 52 warehouses, 60 intermediate shaft, 61, 62 camps, 63 printing plate, 64 bolts, 65 sealing ring, 66 mounting bolts, 67 washer, 68 mounting bolts, 69 washer, T F Front section power transmission device, 71 Engine-side rotor (first rotor), 71f Facing surface, 71u First receiving groove, 71v Arched groove, 71p Engine-side pressure projection (first pressure projection), 71k Machining margin, 72 Starter generator side rotor (second rotor), 72a disc, 72s Tubular shaft, 72f Facing surface, 72u Second receiving groove, 72p Starter generator side pressure projection (second pressure projection), 72k machining margin, 75 bow spring, 76 rubber element, T R Rear section power transmission device, 81 Engine-side rotor, 81p Engine-side projection, 81t bridge, 81pp lead, 82 Starter generator side rotor, 82p starter generator side pressure projection, 82pt slant, 85A, 85B rubber structure body, 86 Soft rubber element, 86a, 86b end side section, 86c connecting rib, 86ai, 86bi inner end projection, 86ao, 86bo Outer end projection, 87 Hard rubber element, 87c rubber connecting rib
Claims
[1] Power transmission device comprising: a first rotor (71) and a second rotor (72) rotatably and coaxially arranged with a central axis of rotation (Lc) and facing each other; a single arc spring (75) which is elastically deformable to a high degree and has a small modulus of elasticity, wherein the arc spring (75) is inserted between the first rotor (71) and the second rotor (72) to move the first rotor (71) and to urge the second rotor (72) in opposite directions in one direction of rotation; a first pressure projection (71p) projecting from the first rotor (71) and a second pressure projection (72p) projecting from the second rotor (72), the first pressure projection (71p) and the second pressure projection (72p) being arranged in relative positions on superimposed rotation trajectories; and a rubber member (76) which is elastically deformable to a small extent and has a large modulus of elasticity, the rubber member (76) being inserted between the first pressure projection (71p) and the second pressure projection (72p) with gaps therebetween, wherein the first rotor (71) comprises an engine-side rotor (71), wherein power is transferable between itself and a crankshaft (30) of an internal combustion engine (20); wherein the second rotor (72) comprises a starter-generator-side rotor (72), wherein power is transmittable between itself and an input / output shaft (51) of a starter-generator (50); wherein the first pressure projection (71p) comprises an engine-side pressure projection (71p); and wherein the second pressure projection (72p) comprises a starter-generator-side pressure projection (72p). [2] The power transmission device according to claim 1, wherein the first rotor (71) and the second rotor (72) have a first receiving groove (71u) and a second receiving groove (72u) having an identical arcuate shape defined respectively in their first facing surface (71f) and their second facing surface (72f), which are arranged close to each other and in a facing relationship; and wherein the arc spring (75) has halves respectively received in the first receiving groove (71u) and the second receiving groove (72u), and is interposed between the first rotor (71) and the second rotor (72). [3] The power transmission device according to claim 2, wherein the rubber member (76) is fitted over both the first pressing projection (71p) and the second pressing projection (72p). [4] Power transmission device according to claim 3, wherein the first rotor (71) has: an arcuate groove (71v) defined in the first facing surface (71f) on the same circumference as the first receiving groove (71u); a pair of first pressing projections (71p) arranged in the arcuate groove (71v) near circumferentially opposite ends of the arcuate groove (71v), respectively; and the rubber member (76) fitted over each of the first pressing projections (71p); and wherein the second rotor (72) has: the second receiving groove (72u) open in the second facing surface (72f); and the second pressing projection (72p) projecting from the circumferentially nearly central portion of an arcuate surface of the second facing surface (72f) corresponding to the arcuate groove (71v). [5] The power transmission device according to claim 4, wherein the rubber member (76) fitted over each of the first pressing projections (71p) is received in the arcuate groove (71v). [6] Power transmission device according to claim 5, wherein the first rotor (71) has a disc shape and has a pair of said arcuate grooves (71v) defined transversely to the central rotational axis (Lc) opposite to portions of the first receiving groove (71u) therein; wherein the first rotor (71) has a machining clearance (71k) for unbalance adjustment behind the first receiving groove (71u) which receives one half of the arc spring (75) therein; and wherein the second rotor (72) has a disc shape and has a machining clearance (72k) for the unbalance adjustment transverse to the central rotation axis (Lc) opposite to the second receiving groove (72u). [7] The power transmission device according to claim 1, wherein the starter-generator-side pressing protrusion (71p) disposed between a pair of the rubber members (76) each fitted over a pair of the engine-side pressing protrusions (71p) is positioned closer to one of the rubber members (76) spaced apart from the starter-generator-side pressing protrusion (72p) in the rotational direction when no relative torque load is applied to the engine-side rotor (71) and the starter-generator-side rotor (72). [8] Power transmission device according to claim 1 or 7, wherein the starter generator side rotor (72) has a tubular shaft (72s) projecting from its central portion through the engine side rotor (71) and having the central rotation axis (Lc) as a central axis; wherein a helical gear (33) is slidably supported on the tubular shaft (72s) on its side which is transverse to the engine-side rotor (71) opposite to the starter-generator-side rotor (72); wherein the engine-side rotor (71), which faces the starter-generator-side rotor (72), is fixed to the helical gear (33); and wherein a disc spring (35) is interposed between a sleeve (36) which is prevented from shifting by a stopper (37) engaging an outer periphery of the tubular shaft (72s) on an opposite side of the engine-side rotor (71) with respect to the helical gear (33), and the helical gear (33). [9] The power transmission device according to claim 8, wherein the helical gear (33) has a thread spiral such that when the helical gear (33) operates as a drive gear, the helical gear (33) generates an axial thrust force for pressing the engine-side rotor (71) against the starter-generator-side rotor (72).
Citation Information
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