US20080308053A1 - Variable Valve Drive Device, Engine, and Motorcycle - Google Patents

Variable Valve Drive Device, Engine, and Motorcycle Download PDF

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Publication number
US20080308053A1
US20080308053A1 US11/574,299 US57429905A US2008308053A1 US 20080308053 A1 US20080308053 A1 US 20080308053A1 US 57429905 A US57429905 A US 57429905A US 2008308053 A1 US2008308053 A1 US 2008308053A1
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United States
Prior art keywords
cam
eccentric
rotate
rotation axis
drive member
Prior art date
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Abandoned
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US11/574,299
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English (en)
Inventor
Naoki Tsuchida
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Yamaha Motor Co Ltd
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Yamaha Motor Co Ltd
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Assigned to YAMAHA HATSUDOKI KABUSHIKI KAISHA reassignment YAMAHA HATSUDOKI KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: TSUCHIDA, NAOKI
Publication of US20080308053A1 publication Critical patent/US20080308053A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
    • F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
    • F01L1/356—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear making the angular relationship oscillate, e.g. non-homokinetic drive
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/022—Chain drive
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • F01L1/053—Camshafts overhead type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
    • F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/024—Belt drive
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • F01L2001/0471—Assembled camshafts
    • F01L2001/0473—Composite camshafts, e.g. with cams or cam sleeve being able to move relative to the inner camshaft or a cam adjusting rod
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L2820/00—Details on specific features characterising valve gear arrangements
    • F01L2820/03—Auxiliary actuators
    • F01L2820/032—Electric motors

Definitions

  • the present invention relates to a variable valve drive device that is arranged in an engine, an engine, and a motorcycle.
  • variable valve timing mechanism that changes the opening and closing timing of the valves according to the number of revolutions of an engine.
  • a rotational phase difference is set up between the cam drive shaft part rotating in conjunction with the rotation of the crankshaft and a part that drives the camshaft part to which cams are unitedly fixed.
  • variable valve timing mechanism of this type can be realized by only changing a part of the cam sprocket part rotating in conjunction with the rotation of the crankshaft without largely changing the valve drive mechanism in the conventional engine.
  • the duration of cams cannot be changed, in case of using cams of a large duration so as to obtain a high output, the flow velocity of air fuel mixture flowing into the cylinder is reduced at the time of the low-medium-speed rotation. Accordingly, air fuel mixture becomes hard to vaporize completely in the cylinder, raising a problem that a high output cannot be realized.
  • Patent Document 2 JP Patent Application Laid-Open Publication No. 5-118208
  • an eccentric plate is arranged between a sprocket that rotates when a driving force is transmitted from the crankshaft through a gear train and the camshaft that is unitedly fixed to cams, and a motive energy is transmitted to the camshaft from the sprocket through the eccentric plate.
  • variable valve timing mechanisms are mainly applied to a multi-cylinder engine of an automobile.
  • a multi-cylinder engine since the periodical velocity fluctuation of cams in respective cylinders are required to be staggered by setting different phases, each cylinder has an eccentric plate.
  • Patent Document 4 discloses a technology in which the cam drive shaft itself, which drives the camshaft that is unitedly fixed to cams, is made eccentric with respect to the camshaft by an eccentric mechanism.
  • variable valve timing mechanism In recent years, due to the problem of the exhaust gas regulation etc., mounting the variable valve timing mechanism to motorcycles are being considered.
  • the variable valve timing mechanism When applying the variable valve timing mechanism to a motorcycle, especially to a scooter-type vehicle (referred to as scooter, hereinafter), depending on the restriction of the vehicle dimension, it is desired that the engine configuration is simplified.
  • an engine of a motorcycle has arranged therein an eccentric mechanism such as an eccentric plate between the cam sprocket and the camshaft, the cam sprocket comes to be separated from the cylinder axis, which lowers the flexural strength of the crank. There is raised a problem that it is difficult to mount the variable valve timing mechanism with the lowering of the flexural strength being prevented.
  • the chain line of the cam drive chain which is so arranged as to be substantially perpendicular to the crankshaft is separated from a line on which a cylinder and cams are arranged. Accordingly, an engine itself becomes large by a distance between the arrangement line for the cylinder as well as cams and the chain line.
  • the variable valve timing mechanism is mounted to the engine, the chain line protrudes to the outside of the engine as compared with the conventional engine, raising a problem that the engine itself is enlarged.
  • a sheave for the CVT Continuous Variable Transmission
  • CVT Continuous Variable Transmission
  • wide components such as a sheave are arranged, on the crankshaft, at the outside of rotating parts (crank pulley, timing gear, etc.) around which the cam drive chain is wound with respect to the cylinder position. Accordingly, an engine itself wholly protrudes toward a direction of the crankshaft as compared with the configuration in which the variable valve timing mechanism is not mounted.
  • the present invention has an object to overcome the above-mentioned drawbacks of the prior art by providing a variable valve drive device, an engine, and a motorcycle which can make the duration of cams variable with a simplified configuration without considerably changing the configuration of an engine.
  • a variable valve drive device including: a cam drive member that is made to rotate by a driving force transmitted from a crankshaft; an eccentric member that is made to rotate with an axis of the same direction as the rotation axis of the cam drive member being the rotation center when the cam drive member is driven, and has the axis shiftably arranged from the axile center of the rotation axis to an eccentric position; a camshaft that is arranged on the same axis as the rotation axis, and is made to rotate by the eccentric member with the rotation axis being the rotation center, and the rotational phase difference thereof with respect to the cam drive member periodically fluctuates when the eccentric member is made to rotate at the eccentric position; a cam block that is made to rotate by the camshaft with the same rotational phase as that of the camshaft so as to drive an exhaust valve or an intake valve; wherein the eccentric member is arranged at one end of the cam drive member in the rotation axis direction thereof, and the cam block is arranged at the other end
  • FIG. 1 shows an exploded perspective view of the substantial part of an engine provided with the variable valve drive device according to an embodiment of the present invention.
  • FIG. 2 shows a sectional view of the substantial part of the variable valve drive device.
  • FIG. 3 shows an exploded perspective view of the variable valve drive device.
  • FIG. 4 shows a view indicative of the positional relationship among the rotation center of an eccentric boss, the axile center of a variable camshaft, and the axile center of an eccentric plate.
  • FIG. 5 shows an exploded perspective view of an eccentric boss.
  • FIG. 6 shows a view indicative of an example of the positional relationship between a drive pin and a driven pin in the variable valve drive device according to an embodiment of the present invention when the center of an eccentric plate is made eccentric with respect to a variable camshaft.
  • FIG. 7 shows a view indicative of an example of the valve lift by the variable valve drive device according to an embodiment of the present invention.
  • FIG. 8 shows a view indicative of the flow of lubricant in the variable valve drive device according to an embodiment of the present invention.
  • FIG. 9 shows a schematic side view indicative of the substantial configuration of a motorcycle provided with the variable valve drive device for an engine according to an embodiment of the present invention.
  • FIG. 10 shows a schematic plan view indicative of the substantial part of a drive unit shown in FIG. 9 .
  • FIG. 1 shows an exploded perspective view of the substantial part of an engine provided with the variable valve drive device according to an embodiment of the present invention.
  • FIG. 1 shows an engine 100 that includes an engine main body 110 having a cylinder part 106 having slidably housed therein a piston 102 and a cylinder head 104 , a crankshaft 130 housed in a crank case 112 (refer to FIG. 10 ), and a variable valve drive device 200 .
  • a periodical rotational phase difference is set up between an exhaust cam block 220 and an intake cam block 240 by the variable valve drive device 200 that is arranged substantially in parallel with the crankshaft 130 so as to make the opening and closing valve timing variable according to the respective rotations. Accordingly, the valve overlap is made variable according to the number of rotations of the engine 100 .
  • the engine 100 is of the single cylinder SOHC (Single Over Head Camshaft) type to be mounted to a scooter-type motorcycle 500 (refer to FIG. 9 ).
  • the engine 100 is of the single cylinder SOHC type, to which the present invention is not restricted, and an engine of any type may be employed so long as the engine includes the variable valve drive device 200 .
  • the piston 102 is slidably (upward and downward) arranged in the cylinder part 106 in a direction of the cylinder axis, and has its one end connected to the crankshaft 130 through a connecting rod 108 .
  • the connecting rod 108 is rotatably attached to a crank pin, not shown, arranged between crank webs 132 mounted on the crankshaft 130 . Accordingly, the piston 102 slides inside the cylinder part 106 when the crankshaft 130 rotates.
  • a timing gear 134 is mounted, neighboring the crank web 132 (more specifically, crank journal).
  • a cam drive chain 133 as a driving force transmission member is wound.
  • This cam drive chain 133 is wound around, in addition to the timing gear 134 , a cam sprocket 211 arranged in the cylinder head 104 of the engine main body 110 , and transmits a rotational driving force to the exhaust cam block 220 as well as the intake cam block 240 of the variable valve drive device 200 .
  • the transmission line (chain line, in this embodiment) of the cam drive chain 133 is substantially perpendicular to the crankshaft 130 , and is arranged at a position in close proximity to the cylinder axis of the cylinder part 106 in which the piston 102 slides. The reason is to prevent the bending stress applied to the crank itself from becoming large, the bending stress being structurally enlarged in case the cam drive chain 133 is distant from the crank part for driving the piston 102 , when a tensile force is applied to the cam drive chain 133 .
  • the cam drive chain 133 is arranged in a chain case part 116 that is unitedly formed with the cylinder part 106 of the engine main body 110 .
  • the upper part (referred to as case upper part, hereinafter) 116 a of the chain case part 116 is arranged on the cylinder head 104 , and the case upper part 116 a is opened on the cylinder head 104 in a direction parallel with the crankshaft 130 .
  • one opening 116 b communicates with the space located over the cylinder part 106
  • the other opening 116 c is provided with an annular cylinder head cover (referred to as head cover, hereinafter) 105 .
  • the annular head cover 105 has arranged therein one end of the variable valve drive device 200 , and the variable valve drive device 200 has its one end supported by the head cover 105 .
  • the variable valve drive device 200 includes the cam sprocket 211 , the exhaust cam block 220 , a variable camshaft 230 , the intake cam block 240 , an eccentric plate 250 , an eccentric boss 260 , and an eccentricity-causing motor 270 , and is attached to the cylinder head 104 in a direction substantially parallel with the crankshaft 130 .
  • FIG. 2 shows a sectional view of the substantial part of the variable valve drive device 200 attached to the cylinder head 104
  • FIG. 3 shows an exploded perspective view of the variable valve drive device 200 .
  • variable valve drive device 200 rotation axes of the cam sprocket 211 , exhaust cam block 220 , variable camshaft 230 , intake cam block 240 , eccentric plate 250 , and eccentric boss 260 are parallel with respect to one another.
  • variable valve drive device 200 As shown in FIG. 1 to FIG. 3 , the intake cam block 240 and the exhaust cam block 220 are arranged in the cylinder head 104 over the cylinder part 106 with the variable camshaft 230 inserted therein. Furthermore, the variable camshaft 230 is inserted in the cam sprocket 211 , and the cam sprocket 211 and the eccentric plate 250 are arranged in the case upper part 116 a.
  • the eccentric boss 260 is rotatably arranged in the annular head cover 105 , while the head cover 105 is fixed to the cylinder head 104 . Accordingly, the variable valve drive device 200 is fixed to the cylinder head 104 .
  • the cam sprocket 211 is unitedly formed with the exhaust cam block 220 that has the same axile center and rotates to open and close the valve (exhaust valve, in this case) through a tubular part 224 . That is, these cam sprocket 211 , tubular part 224 , and exhaust cam block 220 configure a cam drive section 210 that directly receives a driving force of the crankshaft 130 to rotate.
  • the cam sprocket 211 is driven by the crankshaft 130 through the timing gear 134 (refer to FIG. 1 ) and the cam drive chain 133 (refer to FIG. 1 ), and rotates under a constant reduction gear ratio with respect to the number of rotations of the crankshaft 130 .
  • the cam sprocket 211 rotates with half the rotational speed of the crankshaft 130 .
  • the axile center of the cam sprocket 211 and the exhaust cam block 220 is set to the camshaft axile center, and the camshaft axile center is arranged substantially in parallel with the crankshaft 130 (refer to FIG. 1 ) over the cylinder part 106 .
  • the cam sprocket 211 is provided with a drive pin 212 that rotates the eccentric plate 250 , in such a state that drive pin 212 is so arranged as to be substantially in parallel with the rotational axis of the cam sprocket 211 and protrude toward the opposite direction with respect to the exhaust cam block 220 .
  • the drive pin 212 is fitted with allowance in a slot 252 that is formed by cutting off part of the eccentric plate 250 from the center thereof in the radius direction.
  • the axile center of the drive pin 212 is made eccentric with respect to the axile center of the cam sprocket 211 .
  • the drive pin 212 is made to rotate around the axile center of the cam sprocket 211 to rotate the eccentric plate 250 whose rotational axis is parallel with the drive pin 212 through the slot 252 .
  • the cam sprocket 211 has attached thereto a protrusion piece 114 that protrudes in the radius direction thereof.
  • the protrusion piece 114 has its rotation position sensed by a sensor 114 a that is attached to the cylinder head 104 .
  • the cam sprocket 211 Since a driving force of the crankshaft 130 is directly transmitted to the cam sprocket 211 through the cam drive chain 133 (refer to FIG. 1 ), the cam sprocket 211 has its rotation position determined in conjunction with the stroke of the crank. That is, the rotation position includes information of strokes of the crank (intake stroke, compression stroke, expansion stroke, and exhaust stroke, in case of the four-cycle). Accordingly, the stroke of the crank can be determined when the sensor 114 a detects the position of the protrusion piece 114 attached to the cam sprocket 211 .
  • the same axile center of the cam sprocket 211 , exhaust cam block 220 , and tubular part 224 , or the axile center of the cam drive section 210 is provided with an insertion opening 215 that passes through in the axis direction.
  • the insertion opening 215 communicates with an opening 223 (refer to FIG. 2 ) that is formed on the base circle surface of the exhaust cam block 220 .
  • a shaft part 230 a of the variable camshaft 230 is rotatably inserted in the axis direction.
  • the shaft part 230 a of the variable camshaft 230 protrudes from both sides of the cam drive section 210 in the axis direction, and the intake cam block 240 neighboring the exhaust cam block 220 is unitedly attached to part thereof protruding at the exhaust cam block 220 side.
  • the shaft part 230 a of the variable camshaft 230 is provided with a driven pin 232 at part thereof protruding at the cam sprocket 211 side of the cam drive section 210 .
  • variable camshaft 230 is inserted in the cam drive section 210 and is so arranged as to get across over the cylinder part 106 .
  • bearing 104 a and a bearing 113 which rotatably support the variable camshaft 230 .
  • variable camshaft 230 is provided with a penetration opening 238 that passes through the inside of the shaft part 230 a in the axis direction, and the penetration opening 238 works as the main path for lubricant to be supplied to the sliding parts of the members of the variable valve drive device 200 .
  • the penetration opening 238 is explained as a main lubricant path 238 .
  • the main lubricant path 238 communicates with the outer circumference surface of the shaft part 230 a through branched lubricant paths 239 a , 239 b , 239 c , and has its one end opened through an iris 235 that is arranged in the shaft part 230 a at the chain line side.
  • the branched lubricant paths 239 a , 239 b , 239 c are so formed as to be perpendicular to the main lubricant path 238 at the shaft part 230 a , and are opened at the outer circumference surface of the shaft part 230 a , respectively.
  • lubricant-pooling grooves 236 , 237 are formed at the outer circumference surface of the shaft part 230 a , where the branched lubricant paths 239 a , 239 b are opened, there are formed lubricant-pooling grooves 236 , 237 in the form of recesses in the circumference direction thereof, and the branched lubricant paths 239 a , 239 b communicate with the lubricant-pooling grooves 236 , 237 .
  • the lubricant-pooling grooves 236 , 237 are formed at the insertion opening 215 configured by the inner surface of the tubular part 224 and exhaust cam block 220 , where the outer circumference surface of the variable camshaft 230 is in contact therewith, and are filled with lubricant conducted by the branched lubricant paths 239 a , 239 b.
  • the branched lubricant path 239 c is so formed as to be perpendicular to the shaft part 230 a from the main lubricant path 238 , and is opened to communicate with an opening 245 of the intake cam block 240 .
  • lubricant conducted by the branched lubricant path 239 c is supplied to the part where the shaft part 230 a is in contact with the intake cam block 240 , lubricating the sliding part. Furthermore, at the intake cam block 240 , where the outer circumference surface of the shaft part 230 a is in contact therewith, there is formed a lubricant-pooling groove 246 along the inner circumference surface of the intake cam block 240 formed at the opening thereof.
  • variable camshaft 230 One end of the variable camshaft 230 is inserted into the bearing 113 attached to the cylinder head 104 . Part of the variable camshaft 230 protruding from the bearing 113 is covered by an oil seal cap 115 , and an oil seal part 117 prevents lubricant from leaking to the outside of the cylinder head 104 .
  • One end 111 of the cylinder head 104 is provided with a discharge outlet 118 of an oil pump.
  • Lubricant is pressed into an oil-pooling space 119 that communicates with an opening 230 c formed at one end of the shaft part 230 a through the discharge outlet 118 , and lubricant is conducted to the main lubricant path 238 through the oil-pooling space 119 .
  • the intake cam block 240 is fitted to the outside of one end of the shaft part 230 a , and a pin 241 is fitted into a cutout 243 (refer to FIG. 3 ) formed on the inner circumference surface of the intake cam block 240 , fixing the intake cam block 240 .
  • the intake cam block 240 is arranged over the cylinder part 106 together with the exhaust cam block 220 .
  • the intake cam block 240 When the variable camshaft 230 rotates with its axile center being the rotation center, the intake cam block 240 is made to rotate with the same axile center being the rotation center. Furthermore, as shown in FIG. 2 , the intake cam block 240 has formed thereon the opening 245 penetrating from the base circle surface thereof to the opening inner surface thereof formed at one end of the outer circumference surface of the shaft part 230 a . The opening 245 communicates with the main lubricant path 238 inside the shaft part 230 a.
  • the main lubricant path 238 is formed in the shaft part 230 a of the variable camshaft 230 , penetrating therethrough in the axis direction, and the variable camshaft 230 has its another end made to neighbor the eccentric plate 250 and has its one end provided with the intake cam block 240 . Accordingly, the main lubricant path 238 penetrates the intake cam block 240 , exhaust cam block 220 , and further penetrates the cam sprocket 211 neighboring the exhaust cam block 220 , getting to the eccentric plate 250 .
  • the main lubricant path 238 penetrates the cam sprocket 211 from one end thereof and has its another end opened through the iris 235 .
  • the iris 235 optimally distributes lubricant to be supplied to the valve drive part (exhaust cam block 220 , intake cam block 240 ) side and to the variable mechanism part (eccentric plate 250 , drive pin 212 , driven pin 232 , slots 252 , 254 , etc.) side.
  • the main lubricant path 238 gets across in the cylinder head 104 over the cylinder part 106 .
  • lubricant supplied from one end of the shaft part 230 a passes over the cam sprocket 211 that is directly driven by the crankshaft 130 , and flows to the eccentric plate 250 located at the other end of the shaft part 230 a through the iris 235 .
  • the shaft part 230 a has its another end provided with a plate 234 , which extends in a direction substantially perpendicular to the axile center of the shaft part 230 a .
  • the plate 234 is made to rotate at a position neighboring the cam sprocket 211 when the shaft part 230 a rotates.
  • the plate 234 is provided with the driven pin 232 (refer to FIG. 1 to FIG. 3 ), which protrudes in a direction opposite to the direction along which the shaft part 230 a extends.
  • the driven pin 232 is arranged in parallel with the axile center of the shaft part 230 a , and is located at a position eccentric with respect to the axile center of the shaft part 230 a on the opposite side of the drive pin 212 when viewed from the shaft part 230 a.
  • the driven pin 232 is fitted with allowance in a slot 254 that is formed by cutting off part of the eccentric plate 250 from the center thereof in the radius direction, and is made to rotate around the axile center of the shaft part 230 a when the eccentric plate 250 rotates. That is, when the drive pin 212 , which is made to rotate when the cam sprocket 211 rotates, rotates the eccentric plate 250 , the intake cam block 240 is made to rotate when the variable camshaft 230 , which is driven by the eccentric plate 250 through the driven pin 232 , rotates.
  • the eccentric plate 250 includes a plate main body 256 in the form of a plate that is so arranged as to neighbor the plate 234 of the variable camshaft 230 , and a plate shaft part 258 arranged at the center of the plate main body 256 .
  • the plate main body 256 has formed thereon the slot 252 and the slot 254 in alignment, sandwiching the plate shaft part 258 , in which the drive pin 212 and the driven pin 232 are fitted with allowance respectively.
  • the plate shaft part 258 is so formed as to be perpendicular to the plate main body 256 and protrude to the side opposite to the plate 234 , and is rotatably inserted in an eccentric opening 262 formed through the eccentric boss 260 .
  • the eccentric opening 262 is formed through an eccentric boss main body 264 that is rotatably arranged in the inside of the head cover 105 attached to the cylinder head 104 , and is located at a position eccentric with respect to the rotation center R (refer to FIG. 3 ).
  • the eccentric boss main body 264 has a rack 266 formed on part of the outer circumference thereof, which is engaged with a worm gear 272 of the eccentricity-causing motor 270 attached to the head cover 105 . Accordingly, when the eccentricity-causing motor 270 is driven, the eccentric opening 262 can shift, keeping its position eccentric with respect to the rotation center R of the eccentric boss main body 264 .
  • FIG. 4 shows a view indicative of the positional relationship among the rotation center R of the eccentric boss 260 , the axile center C of the variable camshaft 230 , and the axile center E of the eccentric plate 250 .
  • the eccentric boss 260 is rotatably fitted into the head cover 105 , and is made to rotate by the eccentricity-causing motor 270 (refer to FIG. 1 to FIG. 3 ) with the rotation center (boss center) R being the center.
  • the rotation center R is fixed to the engine side, and is the rotation center of the axile center (eccentricity center) E with respect to the axile center C of the variable camshaft 230 , exhaust cam block 220 , and intake cam block 240 .
  • the axile center E of the plate shaft part 258 or the eccentric plate 250 is rotatably inserted to the eccentric opening 262 of the eccentric boss 260 , when the eccentric boss 260 rotates, the axile center (eccentricity center) E of the eccentric plate 250 is made to shift with the rotation center (boss center) R being the center, depicting a circular arc. Furthermore, on a line along which the axile center (eccentricity center) E shifts, the axile center C of the variable camshaft 230 or the axile center C of the exhaust cam block 220 and intake cam block 240 is located.
  • the axile center E of the eccentric plate 250 is made eccentric with respect to the axile center C of the variable camshaft 230 , which can bring about a phase difference in the rotation of the intake cam block 240 united with the variable camshaft with respect to the rotation of the exhaust cam block united with the cam sprocket 211 .
  • the rotation of the eccentric boss 260 can make the axile center E accord with the axile center C.
  • the eccentric boss 260 can be fixed. Accordingly, the eccentric plate 250 and the variable camshaft 230 can be made to rotate with the same axile center being the rotation center.
  • the rotation angle of the eccentric boss 260 in the head cover 105 is detected by angle sensors 26 , 27 which are attached to the eccentric boss 260 , as shown in FIG. 2 .
  • the eccentric position of the eccentric opening 262 is controlled to be set to a predetermined position by a control unit, not shown.
  • FIG. 5 shows an exploded perspective view of the eccentric boss 260 .
  • the eccentric boss main body 264 of the eccentric boss 260 is in the form of a cylinder having the bottom, and is formed by attaching a lid 264 b to a main case 264 a having formed therethrough the eccentric opening 262 .
  • the main case 264 a has formed therein separated spaces 267 a , 267 b , 267 c around the eccentric opening 262 , the spaces being partitioned by partition walls 265 a , 265 b , 265 c.
  • Each of the partition walls 265 a , 265 b is provided with a cutout 269 that makes the separated space 267 a communicate with the separated space 267 b , and makes the separated space 267 b communicate with the separated space 267 c.
  • the lid 264 b covers the separated spaces 267 a , 267 b , 267 c .
  • the lid 264 b has formed therethrough an opening 264 c at a position corresponding to the ceiling of the separated space 267 c.
  • the eccentric boss 260 is of communicating configuration in the axis direction or from the front side to the rear side through the air holes 268 , separated spaces 267 a , 267 b , 267 c , cutouts 269 , and opening 264 c . That is, even if the eccentric boss 260 is attached to the cylinder head 104 through the head cover 105 , the eccentric boss 260 can make the front side thereof communicate with the rear side thereof in the cylinder head 104 .
  • the head cover 105 has formed therethrough oil return holes 105 a substantially in parallel with the rotation axile center of the eccentric boss 260 .
  • the lubricant is made to return to flow into the engine 100 through the oil return holes 105 a together with the oil return hole 268 a making the separated space 267 a communicate with the outside thereof. That is, the separated spaces 267 a , 267 b , 267 c work as breather spaces which prevent discharging lubricant in blow-by gas raised in the engine 100 to the outside of the engine 100 .
  • variable valve drive device 200 in this embodiment will be explained.
  • variable valve drive device 200 shown in FIG. 1 to FIG. 3
  • the cam sprocket 211 is made to rotate through the cam drive chain 133 with half the rotational speed of the crankshaft 130 .
  • the exhaust cam block 220 that is unitedly attached to the cam sprocket 211 through the tubular part 224 is made to rotate. That is, the exhaust cam block 220 rotates in synchronization with the rotation of the crankshaft 130 .
  • the drive pin 212 that is fitted with allowance in the slot 252 of the eccentric plate 250 presses the eccentric plate 250 through the slot 252 with the plate shaft part 258 being the supporting point so as to rotate the eccentric plate 250 . Since the rotation center of the eccentric plate 250 , that is, the position of the plate shaft part 258 is made eccentric due to the drive of the eccentricity-causing motor 270 , even if the cam sprocket 211 rotates with a constant rotational speed, the eccentric plate 250 is made to rotate with a non-constant rotational speed.
  • FIG. 6 shows a view indicative of an example of the positional relationship between the drive pin 212 and the driven pin 232 in the present variable valve drive device 200 when the center of the eccentric plate 250 is made eccentric with respect to the variable camshaft 230 .
  • FIG. 6( a ) to FIG. 6( i ) show the relative positional relationship between the drive pin 212 and the driven pin 232 in stages when the crankshaft 130 is made to rotate with a predetermined rotational speed. Since the slots 252 and 254 (refer to FIG. 1 to FIG. 3) in which the drive pin 212 and driven pin 232 are fitted with allowance are formed in alignment, thus formed line is simply represented by a straight line SL.
  • the distance between the center of the eccentric plate 250 and the center of the drive pin 212 becomes shorter than the distance between the center of the cam sprocket 211 and the center of the drive pin 212 . Accordingly, the rotation angle of the eccentric plate 250 becomes larger than the rotation angle of the cam sprocket 211 .
  • the slot 254 formed on the plate main body 256 of the eccentric plate 250 is made to rotate with a non-constant rotational speed similar to the eccentric plate 250 . Since the driven pin 232 that is fitted with allowance in the slot 254 is concentric with the cam sprocket 211 and the intake cam block 240 , the rotation with a non-constant rotational speed is transmitted to the driven pin 232 through the slot 254 . Then, the shaft part 230 a is made to rotate with a non-constant rotational speed through the driven pin 232 to which the rotation with a non-constant rotational speed is transmitted, which makes the intake cam block 240 rotate with a non-constant rotational speed.
  • the intake cam block 240 rotates with an angular speed that is faster than half the rotational speed of the crankshaft 130 around the crank angle at which the intake cam block 240 is opened.
  • the crank rotates by the duration (for example, 268 degrees)
  • the intake cam is made to rotate more than the duration
  • the intake valve is opened and closed in a shorter time period. That is, the duration is made narrow.
  • the duration is made broad.
  • the rotational phase difference of the intake cam block 240 that is made to rotate by the variable camshaft 230 driven through the eccentric plate 250 periodically fluctuates with respect to the exhaust cam block 220 that is unitedly attached to the cam sprocket 211 . That is, the duration of the intake cam block 240 periodically varies, that is, the intake cam block 240 rotates with a non-constant rotational speed, which varies the duration as well as opening and closing timing of the intake valve (variable valve) to be opened and closed by the rotation.
  • At which timing the intake cam block 240 should be made to rotate with a higher speed and should be made to rotate with a lower speed with respect to the exhaust cam block 220 is determined by the positional relationship among the center of the eccentric plate 250 and the cam nose as well as the respective slots 252 , 254 with respect to the center of the cam sprocket 211 .
  • FIG. 7 shows a view indicative of an example of the valve lift by the variable valve drive device 200 according to an embodiment of the present invention.
  • a lift curve K indicates the lift amount by the intake valve
  • a lift curve H indicates the lift amount by the exhaust valve.
  • OT, OT 1 , OT 2 indicate the opening timing of the variable valve (intake valve, in this case), while TT, TT 1 , TT 2 indicate the closing timing thereof.
  • the duration (also referred to as working angle) D 1 of the intake cam block 240 , valve overlap D 2 , maximum lift angles D 3 , D 4 are shown.
  • variable valve drive device 200 when the eccentric boss 260 rotates, and the position of the eccentric opening 262 or the rotation center of the eccentric plate 250 is made eccentric with respect to the camshaft, the lift curve K is varied as shown by lift curves K 1 , K 2 .
  • the rotational speed of the cam is made low during a period when the valve is opened, while the rotational speed of the cam is made high when the valve is closed.
  • the rotational speed of the cam is made high during a period when the valve is opened, while the rotational speed of the cam is made low when the valve is closed.
  • the intake cam block 240 can be made to rotate with a periodical rotational phase difference set up with respect to the exhaust cam block 220 , and the rotational phase difference can be arbitrarily varied, the length of the valve overlap D 2 can be varied depending on the engine stroke.
  • the interfusion of residual gas can be prevented, making it possible to combust gas with stability.
  • the scavenging for the residual gas due to the effect of the exhaust-pulse and reduction of blowing back can be realized.
  • the intake effect for air fuel mixture is improved, which enables taking in sufficient air fuel mixture, making it possible to stabilize the idling as well as improve the starting capability.
  • blow-bye can be prevented, and hydrocarbon contained in exhaust gas can be reduced, and the engine power at a low rotational speed can be enhanced, enabling the improvement of the fuel consumption.
  • the intake cam block 240 is made to rotate such that the intake valve is fully closed when the piston 102 gets to the bottom dead point.
  • the pumping loss can be reduced by largely opening the intake valve earlier to largely gain the overlap, which can improve the combustion efficiency, enabling the improvement of the fuel consumption.
  • variable valve drive device 200 lubricant is effectively supplied to the sliding parts of the members.
  • FIG. 8 shows a view indicative of the flow of lubricant in the variable valve drive device 200 according to an embodiment of the present invention.
  • lubricant that is pumped up from an oil pan 620 (refer to FIG. 9 ) by a pump, not shown, is discharged from the discharge outlet 118 .
  • Lubricant coming from the discharge outlet 118 flows (in a direction of an arrow S 1 shown in FIG. 8 ) into the oil-pooling space 119 in the oil seal cap 115 that is arranged at the one end 111 (end of the cylinder part 106 ) side of the sealed cylinder head 104 .
  • the flowing lubricant is made to flow (in a direction of an arrow S 2 shown in FIG. 8 ) into the main lubricant path 238 in the shaft part 230 a from the opening 230 c formed at one end of the rotating shaft part 230 a.
  • Lubricant flowing into the main lubricant path 238 flows to the chain line side of the shaft part 230 a .
  • the lubricant passes through the branched lubricant path 239 c , and flows (in a direction of an arrow S 3 shown in FIG. 8 ) to the outside of the intake cam block 240 from the opening 245 , reducing the friction raised in the sliding part of the intake cam block 240 .
  • lubricant in the main lubricant path 238 flows (in a direction of an arrow S 4 shown in FIG. 8 ) into the lubricant-pooling groove 237 from the branched lubricant path 239 b to lubricate the sliding part raised with the exhaust cam block 220 .
  • lubricant coming from (in a direction of the arrow S 4 shown in FIG. 8 ) the branched lubricant path 239 c lubricate the base circle surface of the exhaust cam block 220 from the opening 223 .
  • lubricant in the main lubricant path 238 flows (in a direction of an arrow S 5 shown in FIG. 8 ) into the lubricant-pooling groove 236 from the branched lubricant path 239 a to lubricate the sliding part between the tubular part 224 and the bearing 104 a arranged in the cylinder head 104 .
  • lubricant in the main lubricant path 238 flows (in a direction of an arrow S 6 shown in FIG. 8 ) to the chain line side of the shaft part 230 a , and flows to the outside from one end of the shaft part 230 a , specifically, from the axile center thereof located at the surface of the plate 234 through the iris 235 .
  • lubricant coming from the main lubricant path 238 lubricates the sliding part raised with other members of the eccentric plate 250 .
  • lubricant discharged from (in directions of arrows S 7 , S 8 shown in FIG. 8 ) the variable camshaft 230 lubricates the sliding parts between the plate main body 256 (slots 252 , 254 ) and the drive pin 212 as well as the driven pin 232 .
  • the drive pin 212 is made of material that is obtained by treating steel product of high hardness with heat
  • the eccentric plate 250 is made of high alloy steel, cast iron, or sintered alloy of iron which are excellent in abrasion resistance, and the slots 252 , 254 have their surface treated so as to improve the hardness.
  • the sliding part between the cam sprocket 211 and the cam drive chain 133 (refer to FIG. 1 ) is lubricated (in directions of arrows S 9 , S 10 shown in FIG. 8 ) by lubricant.
  • variable valve drive device 200 as compared with a camshaft that is not provided with the variable valve drive mechanism, or the variable valve timing mechanism, the positional relationship among the exhaust cam block 220 , intake cam block 240 , and cam sprocket 211 is not varied on the cam axis line.
  • variable valve drive device 200 can be mounted by replacing the camshaft with the variable valve drive device 200 .
  • variable valve drive device 200 in mounting the variable valve drive device 200 , the dimension, arrangement position, etc. of the respective members to drive the camshaft such as the crankshaft, and the cylinder part, cylinder head, timing gear, etc. of the engine main body do not have to be changed.
  • the variable valve drive device 200 and the head cover 105 are dismounted from the engine main body 110 .
  • a crankshaft which is not provided with the variable mechanism such as the eccentric plate 250 , and includes a cam sprocket, an exhaust cam block, an intake cam block, etc. is inserted into the cylinder head, and a head cover that is formed to correspond to the crankshaft is fixed to the cylinder head. In this way, it becomes possible to easily change the motorcycle 500 provided with the variable valve drive device 200 to a motorcycle that is not provided with the variable valve drive device 200 .
  • a vehicle to which the engine 100 is mounted is a scooter-type motorcycle.
  • a vehicle to which the engine 100 is mounted is not restricted to this, and any vehicle may be employed so long as the vehicle has mounted thereto the engine 100 .
  • FIG. 9 shows a schematic side view indicative of the substantial configuration of a motorcycle provided with the variable valve drive device for an engine according to an embodiment of the present invention.
  • the front, rear, left, right mean the front, rear, left, right which are seen at the time of sitting on the seat of the motorcycle.
  • the motorcycle in this embodiment is of the scooter-type.
  • any vehicle may be employed so long as the vehicle is provided with the valve drive device.
  • the motorcycle 500 shown in FIG. 9 is of the tandem-scooter-type, and includes a vehicle main body 503 that pivotably supports a handle 502 at the front side thereof, and a tandem seat 504 that is arranged at the rear side of the vehicle main body 503 .
  • the tandem seat 504 is openably attached to a trunk space 505 arranged on the lower side. Under the trunk space 505 , there is arranged a drive unit 600 .
  • the front end of the drive unit 600 is swingably attached to the rear side of a front side main body 503 a that extends backward from the lower side of the handle 502 to the lower side of the tandem seat 504 in the upward and downward direction through a pivot shaft, not shown, which is arranged on the level in a direction of the vehicle width.
  • rear wheels 508 are attached through an axile 510 , and there are suspended rear suspensions 512 between the rear ends of the axile 510 and frame pivots which support the rear end of the trunk space 505 .
  • the front end of the trunk space 505 is located at the upper front side of the front end of the drive unit 600 .
  • FIG. 10 shows a schematic plan view indicative of the substantial part of the drive unit 600 shown in FIG. 9 .
  • the engine 100 is mounted at the front side of the vehicle, and a driving force generated from the engine 100 is transmitted to the axile 510 that is attached to the rear end of the drive unit 600 through a CTV mechanism 610 to rotate the rear wheels 508 .
  • the engine 100 has the axis line of the cylinder part 106 made substantially horizontal, and has the crankshaft 130 made substantially parallel with a direction of the vehicle width, and is arranged at substantially the central part in the forward and backward direction of the vehicle under the trunk space 505 .
  • the CTV mechanism 610 is arranged substantially in parallel with the cylinder axis, and includes a pulley 611 attached to the crankshaft 130 , a pulley 612 attached to the axile 510 , a belt 613 that is wound around the pulleys 611 , 612 , and a centrifugal clutch 614 .
  • the centrifugal clutch 614 is attached to the axile 510 . Furthermore, the axile 510 has attached thereto a reduction gear 615 that reduces the speed brought about by a driving force of the crankshaft 130 which is transmitted through the pulley 611 and belt 613 .
  • variable valve timing mechanism is mounted to motorcycles, and especially, in case of applying the variable valve timing mechanism to a scooter-type vehicle (referred to as scooter, hereinafter), so as to restrict the vehicle dimension, it is desirable that the engine configuration is simplified.
  • scooter scooter-type vehicle
  • the eccentric plate 250 that corresponds to the eccentric member is not arranged between the cam drive section 210 that corresponds to the cam drive shaft and the exhaust and intake cam blocks 220 , 240 which are arranged over the cylinder part 106 in the conventional engine configuration.
  • the exhaust and intake cam blocks 220 , 240 are arranged along a cylinder axis line CL over the cylinder part 106 , being different from the conventional configuration, the cylinder axis line and the cam chain line are arranged at positions neighboring one another.
  • a chain line L of the engine 100 is located at a position in close proximity to the cylinder axis line CL.
  • the belt 613 line of the CTV mechanism 610 which is arranged substantially in parallel with the chain line L at the outside of the chain line L comes close to the cylinder axis line CL as compared with the conventional configuration.
  • the width of the drive unit 600 itself becomes small. Specifically, in the drive unit 600 , by an amount by which the chain line L comes close to the cylinder axis line CL, the left side end surface 600 a comes close to the right side end surface as compared with the left side end surface 600 b in the case in which an engine provided with a variable valve drive device of the conventional configuration is mounted.
  • the scooter-type motorcycle 500 is provided with parts arranged at the outside of the cam drive chain 133 on the crankshaft 130 such as a sheave for the CVT (Continuously Variable Transmission).
  • CVT Continuous Variable Transmission
  • members for the variable valve drive are not arranged between the chain line L of the cam drive chain 133 and the cylinder axis line CL on the camshaft line. Accordingly, on the crankshaft 130 , it is not necessary to provide a space corresponding to the members, and the cam sprocket 211 and the exhaust and intake cam blocks 220 , 240 are not separately arranged as compared with an engine provided with the conventional variable valve timing mechanism.
  • the chain line L of the cam drive chain 133 that is arranged in a direction substantially perpendicular to the crankshaft 130 is not separated from the cylinder axis line CL.
  • the width of the crank case 112 comes to be equal to that in the configuration in which the variable valve timing mechanism is not mounted.
  • a sufficient banking angle can be prepared in the motorcycle 500 , making it possible to secure the motional characteristics.
  • the eccentric mechanism such as the eccentric plate 250 is not arranged between the exhaust and intake cam blocks 220 , 240 and the cam sprocket 211 .
  • substantially similar corresponding components of an engine that is not provided with the variable valve drive device 200 can be used. That is, only by dismounting the variable valve drive device 200 from the cylinder head 104 of the engine main body 110 , and changing the eccentric plate 250 , variable camshaft 230 , eccentric boss 260 , and head cover 105 , an engine that is not provided with the variable valve drive device 200 can be formed.
  • main engine components such as the cylinder head can be used in common with the conventional engine of the invariable specification.
  • the overlap can be made variable with simplified configuration.
  • the duration of cams can be made variable with simplified configuration without widely changing the engine configuration, making it possible to realize high response and high mileage in the engine.
  • the single cylinder SOHC (Single Over Head Camshaft) type is employed, to which the present invention is not restricted, and the multi-cylinder SOHC type, DOHC (Double Over Head Camshaft) may be employed.
  • SOHC Single Over Head Camshaft
  • DOHC Double Over Head Camshaft
  • the rotational phase difference of the intake cam block 240 is made to periodically fluctuate with respect to the exhaust cam block 220 , to which the present invention is not restricted. That is, the rotational phase difference of the exhaust cam block 220 may be made to periodically fluctuate with respect to the intake cam block 240 .
  • an intake cam block that rotates unitedly with the cam sprocket 211 and drives the intake valve is arranged, and the variable camshaft 230 is provided with an exhaust cam block that drives the exhaust valve.
  • a variable valve drive device which includes a cam drive member that is made to rotate by a driving force transmitted from a crankshaft, an eccentric member that is made to rotate with an axis of the same direction as the rotation axis of the cam drive member being the rotation center when the cam drive member is driven, and has the axis shiftably arranged from the axile center of the rotation axis to an eccentric position, a camshaft that is arranged on the same axis as the rotation axis, and is made to rotate by the eccentric member with the rotation axis being the rotation center, and the rotational phase difference thereof with respect to the cam drive member periodically fluctuates when the eccentric member is made to rotate at the eccentric position, and a cam block that is made to rotate by the camshaft with the same rotational phase as that of the camshaft so as to drive an exhaust valve or an intake valve, wherein the eccentric member is arranged at one end of the cam drive member in the rotation axis direction thereof, and the cam block is
  • the camshaft is made to rotate with its rotational phase difference with respect to the cam drive member periodically fluctuating.
  • the cam block that is made to rotate with the same rotational phase as that of the camshaft has its rotational phase difference with respect to the cam drive member made to periodically fluctuate. That is, the duration of the cam block becomes variable, which makes the duration of the exhaust valve or intake valve to be driven by the cam block variable. Since the duration of the exhaust valve or intake valve is made variable, the valve overlap becomes variable.
  • the overlap when employed in an engine of the same cylinder capacity, the overlap can be made short at the time of low-speed rotation (including idling) of the engine, while the overlap can be made short at the time of high-speed rotation.
  • the valve when the engine is in the low rotational speed state including the idling, the valve is opened or closed earlier so as to reduce or remove the overlap, which can prevent the interfusion of residual gas (combustion gas), making it possible to combust gas with stability.
  • the scavenging for the residual gas due to the effect of the exhaust-pulse and reduction of blowing back can be realized. Moreover, it becomes possible to stabilize the idling as well as improve the starting capability. Furthermore, blow-bye can be prevented, and hydrocarbon contained in exhaust gas can be reduced, and the engine power at a low rotational speed can be enhanced, enabling the improvement of the fuel consumption.
  • variable valve drive device when the engine is in the medium rotational speed state, the pumping loss can be reduced by largely gaining the overlap, which can improve the combustion efficiency. In this way, employing the variable valve drive device according to the present invention, the engine capability can be improved without changing the cylinder capacity.
  • the eccentric member is not arranged between the cam drive member and the cam block, and the positional relationship between the exhaust valve or intake valve and the cam drive member is similar to that of the conventional engine.
  • the present variable valve drive device can be mounted to a conventional engine without widely changing the engine configuration. That is, main engine components can be used in common in an engine that is provided with the variable valve mechanism and in an engine that is not provided with the variable valve mechanism. Accordingly, in case of mounting the present variable valve drive device to an engine, which is mounted to a motorcycle and is not provided with the variable valve mechanism, it is not necessary to change other engine components such as the cylinder, crankshaft, etc., which can widely reduce the cost.
  • the transmission means does not protrude to the outside, which does not enlarge the width of the engine itself, preventing the reduction of the banking angle as well as the lowering of the travel capability of the vehicle.
  • variable valve drive device further includes a member-shifting part that shifts the axis of the eccentric member from the axis position to an eccentric position with respect to the rotation axis of the cam drive member.
  • the duration of the exhaust valve or intake valve can be made variable.
  • variable valve drive device further includes another cam block that is made to rotate by the cam drive member with the same rotational phase as that of the cam drive member, and is arranged at a position neighboring the cam block.
  • variable valve drive device can be easily mounted to the SOHC type engine in which the intake valve and exhaust valve are arranged on the same camshaft, which can improve the degree of freedom in employing the variable valve drive device.
  • the cam block rotates to drive an intake valve, while another cam block rotates to drive an exhaust valve.
  • the duration of the intake valve can be made variable with respect to the duration of the exhaust valve.
  • the overlap can be largely gained by elongating the opened period of the intake valve, which can secure the engine capability at the time of high-speed rotation without laying down the output capability at the time of low-speed rotation.
  • the cam block rotates to drive an exhaust valve, while another cam block rotates to drive an intake valve.
  • the duration of the exhaust valve can be made variable with respect to the duration of the intake valve.
  • the opened period of the exhaust valve can be made variable without changing the opened period of the intake valve, which can secure the engine capability at the time of high-speed rotation without laying down the idle stability.
  • an eccentricvalve drive device which includes a cam drive member that is made to rotate by a driving force transmitted from a crankshaft, an eccentric member that is arranged at one end of the cam drive member in the rotation axis direction thereof, and is made to rotate with an axis of the same direction as the rotation axis of the cam drive member being the rotation center when the cam drive member is driven, and has the axis shiftably arranged from the axile center of the rotation axis to an eccentric position, a camshaft that is arranged on the same axis as the rotation axis, and is made to rotate by the eccentric member with the rotation axis being the rotation center, and the rotational phase difference thereof with respect to the cam drive member periodically fluctuates when the eccentric member is made to rotate at the eccentric position, a first valve-driving cam block that is arranged at the other end of the cam drive member in the rotation axis direction thereof, and is made to rotate with the same rotational phase as that of the cams
  • variable valve drive device since other members are not arranged between the two valve-driving cam blocks, the variable valve drive device can be compactly configured.
  • an engine which includes a variable valve drive device including a cam drive member that is made to rotate by a driving force transmitted from a crankshaft, an eccentric member that is made to rotate with an axis of the same direction as the rotation axis of the cam drive member being the rotation center when the cam drive member is driven, and has the axis shiftably arranged from the axile center of the rotation axis to an eccentric position, a camshaft that is arranged on the same axis as the rotation axis, and is made to rotate by the eccentric member with the rotation axis being the rotation center, and the rotational phase difference thereof with respect to the cam drive member periodically fluctuates when the eccentric member is made to rotate at the eccentric position, and a cam block that is made to rotate by the camshaft with the same rotational phase as that of the camshaft so as to drive an exhaust valve or an intake valve, wherein the eccentric member is arranged at one end of the cam drive member in the rotation axis direction thereof, the cam block
  • the eccentric member for improving the engine capability is not arranged between the cam drive member and the cam block, and the positional relationship between the exhaust valve or intake valve and the cam drive member is similar to that of the conventional engine, in which the cylinder capacity is not changed. Accordingly, the variable valve drive device can be mounted without widely changing the conventional engine configuration. That is, main engine components can be used in common in an engine that is provided with the variable valve mechanism and in an engine that is not provided with the variable valve mechanism. Accordingly, in case of mounting the variable valve drive device to an engine, which is mounted to a motorcycle and is not provided with the variable valve mechanism, for assembling, it is not necessary to change other engine components such as the cylinder, crankshaft, etc., which can widely reduce the cost in assembling.
  • the width of the crankshaft does not become large accordingly.
  • the driving force transmission line from the crankshaft to the cam drive member is separated from the cylinder axis line on which the cam block is arranged.
  • the transmission means does not protrude to the outside, which does not enlarge the width of the engine itself, preventing the reduction of the banking angle as well as the lowering of the travel capability of the vehicle.
  • an engine which includes a variable valve drive device including a cam drive member that is made to rotate by a driving force transmitted from a crankshaft, an eccentric member that is arranged at one end of the cam drive member in the rotation axis direction thereof, and is made to rotate with an axis of the same direction as the rotation axis of the cam drive member being the rotation center when the cam drive member is driven, and has the axis shiftably arranged from the axile center of the rotation axis to an eccentric position, a camshaft that is arranged on the same axis as the rotation axis, and is made to rotate by the eccentric member with the rotation axis being the rotation center, and the rotational phase difference thereof with respect to the cam drive member periodically fluctuates when the eccentric member is made to rotate at the eccentric position, a first valve-driving cam block that is arranged at the other end of the cam drive member in the rotation axis direction thereof, and is made to rotate with the same rotational phase as that of the
  • the engine can be compactly configured.
  • the engine is of the single cylinder type.
  • the valve when employing the single cylinder type, due to the simply configured variable valve drive device, the valve can be opened and closed corresponding to the engine at the time of low-speed rotation and high-speed rotation.
  • a motorcycle that has mounted thereto the engine such that the crankshaft is arranged in a direction of the vehicle width.
  • the width of the crankshaft does not become large accordingly.
  • the driving force transmission line from the crankshaft to the cam drive member is separated from the cylinder axis line on which the cam block is arranged.
  • the transmission means does not protrude to the outside, which does not enlarge the width of the engine itself, preventing the reduction of the banking angle as well as the lowering of the vehicle travel capability.
  • the duration of cams can be made variable with a simplified configuration without considerably changing the configuration of an engine.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Valve Device For Special Equipments (AREA)
  • Valve-Gear Or Valve Arrangements (AREA)
US11/574,299 2004-08-31 2005-08-02 Variable Valve Drive Device, Engine, and Motorcycle Abandoned US20080308053A1 (en)

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JP2004253621 2004-08-31
JP2004-253621 2004-08-31
PCT/JP2005/014086 WO2006025174A1 (ja) 2004-08-31 2005-08-02 可変バルブ駆動装置、エンジン及び自動二輪車

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US10550738B2 (en) 2017-11-20 2020-02-04 Hyundai Motor Company Continuously variable valve duration apparatus and engine provided with the same
US10634067B2 (en) 2015-12-11 2020-04-28 Hyundai Motor Company System and method for controlling valve timing of continuous variable valve duration engine
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US10415485B2 (en) 2015-12-10 2019-09-17 Hyundai Motor Company Method for controlling of valve timing of continuous variable valve duration engine
US10428747B2 (en) * 2015-12-11 2019-10-01 Hyundai Motor Company System and method for controlling valve timing of continuous variable valve duration engine
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US20180100446A1 (en) * 2015-12-11 2018-04-12 Hyundai Motor Company System and method for controlling valve timing of continuous variable valve duration engine
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US10634067B2 (en) 2015-12-11 2020-04-28 Hyundai Motor Company System and method for controlling valve timing of continuous variable valve duration engine
US10920679B2 (en) 2015-12-11 2021-02-16 Hyundai Motor Company Method for controlling of valve timing of continuous variable valve duration engine
US10634066B2 (en) 2016-03-16 2020-04-28 Hyundai Motor Company System and method for controlling valve timing of continuous variable valve duration engine
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WO2006025174A1 (ja) 2006-03-09

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