EP2644854B1 - Variable valve train for internal combustion engine - Google Patents
Variable valve train for internal combustion engine Download PDFInfo
- Publication number
- EP2644854B1 EP2644854B1 EP13161086.7A EP13161086A EP2644854B1 EP 2644854 B1 EP2644854 B1 EP 2644854B1 EP 13161086 A EP13161086 A EP 13161086A EP 2644854 B1 EP2644854 B1 EP 2644854B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- duty ratio
- connecting pin
- electromagnetic solenoid
- internal combustion
- combustion engine
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000002485 combustion reaction Methods 0.000 title claims description 72
- 239000003921 oil Substances 0.000 claims description 79
- 238000000034 method Methods 0.000 claims description 43
- 230000008569 process Effects 0.000 claims description 43
- 230000001276 controlling effect Effects 0.000 claims description 19
- 239000010687 lubricating oil Substances 0.000 claims description 12
- 239000011435 rock Substances 0.000 claims description 9
- 230000007423 decrease Effects 0.000 claims description 8
- 230000002596 correlated effect Effects 0.000 claims description 6
- 238000005259 measurement Methods 0.000 description 12
- 230000008859 change Effects 0.000 description 9
- 230000000875 corresponding effect Effects 0.000 description 7
- 230000007246 mechanism Effects 0.000 description 7
- 230000002093 peripheral effect Effects 0.000 description 6
- 210000001331 nose Anatomy 0.000 description 4
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 239000000446 fuel Substances 0.000 description 3
- 230000013011 mating Effects 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 210000000887 face Anatomy 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 238000013507 mapping Methods 0.000 description 2
- 230000005347 demagnetization Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
Images
Classifications
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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
- F01L1/12—Transmitting gear between valve drive and valve
- F01L1/18—Rocking arms or levers
- F01L1/181—Centre pivot rocking arms
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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
- F01L1/26—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of two or more valves operated simultaneously by same transmitting-gear; peculiar to machines or engines with more than two lift-valves per cylinder
- F01L1/267—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of two or more valves operated simultaneously by same transmitting-gear; peculiar to machines or engines with more than two lift-valves per cylinder with means for varying the timing or the lift of the valves
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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
- F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
- F01L13/0015—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
- F01L13/0036—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction
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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
- F01L1/02—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
- F01L2001/0535—Single overhead camshafts [SOHC]
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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
- F01L2305/00—Valve arrangements comprising rollers
-
- 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
- F01L2820/031—Electromagnets
Definitions
- the present invention relates to a variable valve train for an internal combustion engine.
- the variable valve train disclosed in the Patent Literature 1 has a structure in which the connecting pin for connecting the adjacent rocker arms together is urged from one side by a spring and pressed from the other side by a moving core of the electromagnetic solenoid.
- Patent Literature 1 discloses no controls over the electromagnetic solenoid other than that described above.
- the electromagnetic solenoid produces less pressure, and therefore a larger amount of power is required to maintain the connected state.
- the demagnetization of the electromagnetic solenoid causes the connecting pin and the moving core to return quickly with the urging force of the spring. Therefore, especially when the moving core is separated from the connecting pin and then further moved by inertia, the moving core is brought into abutting contact with the equivalent of a stopper in the electromagnetic solenoid, which might create a hitting sound.
- Document EP 1736 639 A2 shows a valve actuation device for an internal combustion engine which comprises a cam shaft having thereon at least first and second cams that are different in profile, a first rocker arm that is in contact with the first cam to be swung, the first rocker arm being adapted to actuate an engine valve, a second rocker arm that is in contact with the second cam to be swung, a coupling mechanism that selectively couples and uncouples the first and second rocker arms, and an electric actuating mechanism that actuates the coupling mechanism with an electric power for the selective coupling and uncoupling.
- Document US 2001/0271918 A1 shows a changeover mechanism which is capable of switching between a connection state in which a first rocker arm and a second rocker arm are in connection with each other via a changeover pin and a disconnection state in which the connection is released.
- the changeover mechanism performs energization of actuators for each cylinder in a case in which fuel supply to the internal combustion engine is stopped in response to an establishment of a predetermined stop condition.
- the above-described energization of the actuator for each cylinder is stopped in a case in which a crankshaft of the internal combustion engine stops rotating during an energization time period of the actuator and in which the crankshaft is not driven by an external power.
- an object of the present invention is to provide a variable valve train for an internal combustion engine which duty controls an electromagnetic solenoid for moving a connecting pin, thereby reducing the power consumption of the electromagnetic solenoid and preventing the generation of a hitting sound while preventing an increase in the temperature of the electromagnetic solenoid.
- the present invention provides a variable valve train for an internal combustion engine in which:
- a further feature of the invention described in Claim 1 is that, in a disconnected state of the rocker arms (51, 52) in which the connecting pin (56) is fitted in the other hole portion (52h) of the hole portions to allow the rocker arms (51,52) to rock independently, from a demagnetized state of the electromagnetic solenoid (60), the control means (70) duty controls the electromagnetic solenoid (60) with a normal movement starting duty ratio (a) that causes the connecting pin (56) to start to move against urging force of the spring (54), and then duty controls the electromagnetic solenoid (60) with a connection maintaining duty ratio (b) smaller than the normal movement starting duty ratio (a) to insert the connecting pin (56) into one hole portion (51h) of the hole portions so that the connecting pin (56) extends across both hole portions (51h, 52h), thereby connecting the rocker arms (51,52) together.
- a normal movement starting duty ratio a
- b connection maintaining duty ratio
- a feature of the invention described in Claim 2 is that, in the variable valve train for the internal combustion engine described in Claim 1, a process of duty controlling the electromagnetic solenoid (60) with the normal movement starting duty ratio (a) and then duty controlling the electromagnetic solenoid (60) with the connection maintaining duty ratio (b) is repeated multiple times.
- variable valve train for the internal combustion engine described in Claim 2 further includes oil temperature detecting means (27) for detecting temperature of lubricating oil of the internal combustion engine (10).
- the control means (70) presets a predetermined oil temperature range of approximately 60°C to 80°C.
- the control means (70) repeats multiple times the process of duty controlling the electromagnetic solenoid (60) with the normal movement starting duty ratio (a) that causes the connecting pin (56) to start to move against urging force of the spring (54), and then duty controlling the electromagnetic solenoid (60) with the connection maintaining duty ratio (b) smaller than the normal movement starting duty ratio (a).
- the control means (70) repeats multiple times a process of controlling movement of the connecting pin (56) with a special movement starting duty ratio (a') smaller than the normal movement starting duty ratio (a) and greater than the connection maintaining duty ratio (b), and then duty controlling the electromagnetic solenoid (60) with the connection maintaining duty ratio (b).
- a feature of the invention described in Claim 4 is that, in the variable valve train for the internal combustion engine described in Claim 3, the predetermined oil temperature range is a temperature range in which vibration generated in a cylinder head becomes larger than in other portions.
- a feature of the invention described in Claim 5 is that, in the variable valve train for the internal combustion engine described in Claims 3 and 4, the normal movement starting duty ratio (a) and the special movement starting duty ratio (a') are determined from a map correlated with an oil temperature value.
- a feature of the invention described in Claim 6 is that, in the variable valve train for the internal combustion engine described in any one of Claims 1 to 5, the control means (70) performs control to decrease the duty ratio in a stepwise fashion from the connection maintaining duty ratio (b) that maintains the connected state of the rocker arms (51, 52) by causing the connecting pin (56) to extend across both hole portions (51h, 52h), and adjusts movement speed of the moving core member (61, 62) to stop the moving core member (61, 62), thereby releasing the connection between the rocker arms (51, 52).
- a feature of the invention described in Claim 7 is that, in the variable valve train for the internal combustion engine described in any one of Claims 1 to 5, the control means (70) changes the duty ratio to zero from the connection maintaining duty ratio (b) that maintains the connected state of the rocker arms (51, 52) by causing the connecting pin (56) to extend across both hole portions (51h, 52h), and then controls the duty ratio to a brake duty ratio (b') at a predetermined timing so that the moving core member (61,62) is reduced in movement speed and stopped, thereby releasing the connection between the rocker arms (51, 52).
- a feature of the invention described in Claim 8 is that, in the variable valve train for the internal combustion engine described in Claim 7, the brake duty ratio (b') is determined from the map correlated with the oil temperature value.
- a feature of the invention described in Claim 9 is that, in the variable valve train for the internal combustion engine described in Claim 7, a position of the moving core member (61, 62) is detected by a position sensor, and at a predetermined position, control is performed with the brake duty ratio (b') so that the moving core member (61, 62) is reduced in movement speed and stopped, thereby releasing the connection between the rocker arms (51,52).
- the control means (70) duty controls the electromagnetic solenoid (60) and drives the moving core member (61,62).
- the duty control is also performed when the connection is maintained, the power consumption of the electromagnetic solenoid (60) can be reduced.
- the movement speed of the moving core member (61,62) before stopped is reduced, and thus the generation of a hitting sound due to abutting contact of the moving core member (61, 62) with the equivalent of a stopper can be prevented.
- the control means (70) duty controls the electromagnetic solenoid (60) with the normal movement starting duty ratio (a) that causes the connecting pin (56) to start to move against urging force of the spring (54), and then duty controls the electromagnetic solenoid (60) with the connection maintaining duty ratio (b) smaller than the normal movement starting duty ratio (a).
- a great pressure of the normal movement starting duty ratio (a) at the start of the movement of the connecting pin (56) forces the connecting pin (56) into the one hole portion (51h) to cause the connecting pin (56) to extend across both hole portions (51h, 52h), thereby allowing the connection between the rocker arms (51, 52).
- connection maintaining duty ratio (b) smaller than the normal movement starting duty ratio (a).
- the power consumption of the electromagnetic solenoid can be reduced. Also, when the movement speed of the connecting pin (56) is adjusted to stop the connecting pin (56), the generation of vibration caused by pressing the spring (54) all the way in can be avoided.
- the control means (70) repeats multiple times the process of duty controlling the electromagnetic solenoid (60) with the normal movement starting duty ratio (a), and then duty controlling the electromagnetic solenoid (60) with the connection maintaining duty ratio (b).
- the connecting pin (56) comes out of the one hole portion (51h)
- duty control is repeatedly performed with the normal movement starting duty ratio (a) so that the connecting pin (56) is inserted into the hole portion (51h).
- the connected state can be ensured.
- the connection is finally maintained with the small connection maintaining duty ratio (b)
- the power consumption of the electromagnetic solenoid can be also reduced.
- the lubricating oil for smooth sliding of the connecting pin (56) becomes less viscous.
- the oil temperature is smaller than about 80°C, the coil resistance of the electromagnetic solenoid is small and the coil current flows through easily, so that the projecting force of the moving core member (61, 62) increases.
- the electromagnetic solenoid is energized in the oil temperature range of approximately 60°C to 80°C, the movement speed of the connecting pin (56) is likely to increase, and the connecting pin (56) is not smoothly stopped, thereby making the generation of vibration more likely. Therefore, the predetermined oil temperature range is preset between approximately 60°C and 80°C, and duty control of the electromagnetic solenoid (60) is varied according to within and outside the predetermined oil temperature range.
- the control means (70) repeats multiple times the process of duty controlling the electromagnetic solenoid (60) with the normal movement starting duty ratio (a), and then duty controlling the electromagnetic solenoid (60) with the connection maintaining duty ratio (b) smaller than the normal movement starting duty ratio (a).
- the increase in the movement speed is adjusted by repeatedly changing a great pressure of the normal movement starting duty ratio (a) at the start of the movement of the connecting pin (56) to a smaller pressure of the connection maintaining duty ratio (b), so that the connecting pin (56) can be stopped in a manner extending across both hole portions (51h, 52h).
- the generation of vibration caused by pressing the spring (54) all the way in can be avoided.
- the control means (70) repeats multiple times a process of duty controlling the electromagnetic solenoid (60) with a special movement starting duty ratio (a') smaller than the normal movement starting duty ratio (a) and greater than the connection maintaining duty ratio (b), and then duty controlling the electromagnetic solenoid (60) with the connection maintaining duty ratio (b) smaller than the special movement starting duty ratio (a').
- the pressure change from a value smaller than normal of the special movement starting duty ratio (a') at the start of the movement of the connecting pin (56) to a smaller value of the connection maintaining duty ratio (b) is repeated.
- the movement speed is adjusted to a value suitable for the oil temperature within the predetermined oil temperature range so that the connecting pin (56) can be stopped in a manner extending across both hole portions (51h, 52h).
- the predetermined oil temperature range is a temperature range in which vibration generated in the cylinder head becomes larger than in other portions.
- the insertion duty corresponding to the speed of the connecting pin (56) is applied by the oil temperature, thereby reducing the generation of a hitting sound.
- the movement normal starting duty ratio (a) and the special movement starting duty ratio (a') are determined from a map correlated with an oil temperature value.
- the speed of the moving core member (61, 62) is properly changed depending on the temperature state of the internal combustion engine (more specifically, the change in resistance of the electromagnetic solenoid or in viscosity of lubricating oil with temperature), thereby reducing the generation of a hitting sound.
- control means (70) performs control to decrease the duty ratio in a stepwise fashion from the connection maintaining duty ratio (b) that maintains the connected state of the rocker arms (51,52) by causing the connecting pin (56) to extend across both hole portions (51h, 52h), and adjusts movement speed of the moving core member (61,62) to stop the moving core member (61, 62), thereby releasing the connection between the rocker arms (51,52).
- the movement speed of the moving core member (61, 62) just before stopped can be easily reduced, and the generation of a hitting sound can be prevented.
- the control means (70) changes the duty ratio to zero from the connection maintaining duty ratio (b) that maintains the connected state of the rocker arms (51, 52) by causing the connecting pin (56) to extend across both hole portions (51h, 52h), and then controls the duty ratio to a brake duty ratio (b') at a predetermined timing so that the moving core member (61, 62) is reduced in movement speed and stopped, thereby releasing the connection between the rocker arms (51, 52).
- the movement speed of the moving core member (61, 62) is reduced by the duty control with the duty ratio to a brake duty ratio (b'), thereby allowing an easy reduction in movement speed of the moving core member (61, 62) just before stopped and the prevention of generation of a hitting sound.
- the brake duty ratio (b') is determined from the map correlated with the oil temperature value.
- the moving core member (61,62) is properly braked depending on the temperature state of the internal combustion engine (more specifically, the change in resistance of the electromagnetic solenoid or in viscosity of lubricating oil with temperature), thereby reducing the generation of a hitting sound.
- the position of the moving core member (61, 62) is detected by the position sensor, and at a predetermined position, control is performed with the brake duty ratio (b') so that the moving core member (61, 62) is reduced in movement speed and stopped, thereby releasing the connection between the rocker arms (51,52).
- the moving core member (61, 62) is properly braked and the generation of a hitting sound is reduced.
- FIGs. 1 to 10 an embodiment of the present invention will be described with reference to FIGs. 1 to 10 .
- FIG. 1 shows a partial side view of a motorcycle 1 mounted with an internal combustion engine 10 in accordance with this embodiment.
- the motorcycle 1 includes the internal combustion engine 10 that is suspended through mounting members from a pair of left and right main frames 3 extending rearwardly from a head pipe 2 and bent obliquely downward halfway along its length, and down frames 4 extending obliquely rearward and downward from the head pipe 2.
- the internal combustion engine 10 is the SOHC, two-valve, air-cooled single-cylinder four-stroke internal combustion engine 10.
- the internal combustion engine 10 is composed of a cylinder block 12, a cylinder head 13, and a cylinder head cover 14 sequentially superposed above a crankcase 11 that journals a crankshaft 25.
- the internal combustion engine 10 is provided to stand in a forward-leaning position.
- An intake pipe 15 extends from a rear surface of the cylinder head 13 through a connecting pipe 15c and is connected to an air cleaner 17 through a throttle body 16.
- a fuel injection valve 20 is attached to the intake pipe 15 (see FIG. 2 ).
- An exhaust pipe 18 extending from a front surface of the cylinder head 13 is bent downward and extends rearwardly along the lower surface from the front of the crankcase 11 to be connected to a muffler 19.
- a piston 21 is fitted in a cylinder bore 12b of the cylinder block 12 of the internal combustion engine 10 in such a manner that the piston 21 can reciprocate and slide therein.
- the piston 21 is connected to the crankshaft 25 by a connecting rod 22 to constitute a crank mechanism.
- a combustion chamber 30, facing the piston 21, is formed within the cylinder head 13 in position to correspond the cylinder bore 12b.
- An intake port 31 extends rearwardly from the combustion chamber 30, and an exhaust port 32 extends forwardly from the combustion chamber 30 (see FIG. 2 ).
- the intake pipe 15 is connected to the intake port 31, and the exhaust pipe 18 is connected to the exhaust port 32.
- a spark plug 26 is mounted in a ceiling wall of the combustion chamber 30, with its tip facing the combustion chamber 30 (see FIG. 4 ).
- an intake valve 33 and an exhaust valve 34 are slidably supported by their respective valve guides that are integrally fitted into the cylinder head 13.
- the intake valve 33 and the exhaust valve 34 are upwardly urged by an intake valve spring 35 and an exhaust valve spring 36, respectively, so as to close an intake valve opening of the intake port 31 and an exhaust valve opening of the exhaust port 32, the intake and exhaust valve openings facing the combustion chamber 30.
- the intake valve 33 and the exhaust valve 34 are pressed from above in synchronism with the rotation of the crankshaft 25 by a variable valve train 40 formed above the cylinder head 13, so as to open the intake and exhaust valve openings.
- the variable valve train 40 is formed with left and right opposed camshaft receiving walls 13L and 13R.
- the left and right camshaft receiving walls 13L and 13R each protrude upward on an upper surface of a cam chamber bottom wall 13b inside the cylinder head 13, surrounded by a peripheral wall 13a of the cylinder head 13.
- a camshaft 41 oriented in the left-right direction, is rotatably journaled to the left and right camshaft receiving walls 13L and 13R through bearings 42 and 43.
- the camshaft 41 protrudes leftward through the left camshaft receiving wall 13L, and its protruding portion is mounted with a chain sprocket 44.
- a chain 45 extends between the chain sprocket 44 and a chain sprocket (not shown) fitted into the crankshaft 25.
- the camshaft 41 rotates at a rotational speed of one-half that of the crankshaft 25.
- a chain opening 13h through the cam chamber bottom wall 13b is formed on the left side of the left camshaft receiving wall 13L.
- the chain 45 wrapped around the chain sprocket 44 passes through the chain opening 13h and extends downward, and then passes through a chain chamber 12h of the cylinder block 12 to be wrapped around the chain sprocket fitted into the crankshaft 25 in the crankcase 11.
- an oil storage recess 13d recessed downward is formed in the cam chamber bottom wall 13b of the cylinder head 13 at the rear of the chain opening 13h.
- a sensing portion 27a at the tip of an oil temperature sensor 27 installed from the outside in a rear wall of the peripheral wall 13a of the cylinder head 13 is protruded into the oil storage recess 13d so that the oil temperature sensor 27 can detect the temperature of lubricating oil in the oil storage recess 13d.
- an intake rocker arm shaft 47 is disposed above and obliquely rearward of the camshaft 41, and an exhaust rocker arm shaft 48 is disposed above and obliquely forward of the camshaft 41.
- a first intake rocker arm 51 and a second intake rocker arm 52 adjacent to each other are rockably journaled to the intake rocker arm shaft 47.
- An exhaust rocker arm 53 is rockably journaled to the exhaust rocker arm shaft 48.
- the first intake rocker arm 51 has a roller 51r at an end thereof toward the camshaft 41, and the roller 51r is in contact with a first intake cam lobe 41i of the camshaft 41.
- the first intake rocker arm 51 has an adjusting screw 51s at the other end thereof, and the adjusting screw 51s is in contact with the upper end of a valve stem of the intake valve 33.
- the second intake rocker arm 52 has a roller 52r at an end thereof toward the camshaft 41, and the roller 52r is in contact with a second intake cam lobe 41ii of the camshaft 41.
- the other end 52a of the second intake rocker arm 52 is in contact with the upper end of a lifter 38 received in a receiving recess 13bd formed in the cam chamber bottom wall 13b, the lifter 38 being urged by a coil spring 37 (see FIG. 2 ).
- the first intake cam lobe 41i and the second intake cam lobe 41ii have different profiles.
- the first intake cam lobe 41i and the second intake cam lobe 41ii have cam noses that protrude in the same direction from respective base circles of the same diameter.
- the second intake cam lobe 41ii for a high-load operation region has a higher cam nose and a greater cam operating angle than those of the first intake cam lobe 41i for a low-load operation region.
- the exhaust rocker arm 53 has a roller 53r at an end thereof toward the camshaft 41, and the roller 51r is in contact with an exhaust cam lobe 41e of the camshaft 41.
- the exhaust rocker arm 53 has an adjusting screw 53s at the other end thereof, and the adjusting screw 51s is in contact with the upper end of a valve stem of the exhaust valve 34.
- the first intake rocker arm 51 and the second intake rocker arm 52 respectively have protruding portions 51a and 52a that protrude upward.
- the protruding portions 51a and 52a are respectively formed with recesses 51h and 52h of circular holes of the same diameter, the recesses 51h and 52h opening into adjacent surfaces of the protruding portions 51a and 52a.
- a spring 54 is interposed and a bottomed cylindrical plunger 55 is inserted.
- the plunger 55 is urged by the spring 54 toward the protruding portion 52a of the second intake rocker arm 52 located in a right direction.
- the recess 52h of the second intake rocker arm 52 located on the right side has a circular hole bored in a bottom wall of the recess 52h, that is, the right sidewall.
- a connecting pin 56 is fitted within the recess 52h.
- An extension rod 56b extending to the right of the connecting pin 56 protrudes through the circular hole in the bottom wall of the recess 52h.
- the connecting pin 56 is urged by the spring 54 and fitted only within the recess 52h, so that the left end surface of the connecting pin 56 is kept flush with the adjacent surfaces of the protruding portions 51a and 52a. Even if the recesses 51h and 52h become out of coaxial alignment, the left end surface of the connecting pin 56 is brought into contact with the adjacent surface of the protruding portion 51a of the first intake rocker arm 51, so that the left end surface of the connecting pin 56 is kept flush with the adjacent surface of the protruding portion 51a.
- the plunger 55 is also urged by the spring 54 into contact with the adjacent surface of the protruding portion 52a of the second intake rocker arm 52, so that the plunger 55 is kept flush with the adjacent surface of the protruding portion 52a.
- the cylinder head 13 and the cylinder head cover 14 are joined together with the peripheral wall 13a of the cylinder head 13 and a peripheral wall 14a of the cylinder head cover 14 mating with each other.
- An electromagnetic solenoid 60 is mounted from the outside at the level of right-hand mating faces of the peripheral walls 13a and 14a.
- the pushrod 61 is mounted at the tip thereof with a metallic pressure body 62.
- the pushrod 61 protrudes toward the protruding portion 52a of the second intake rocker arm 52.
- the right end of the extension rod 56b of the connecting pin 56 protruding from the protruding portion 52a of the second intake rocker arm 52 is in contact with the end surface of an end diameter-increased portion 62b, increased in diameter toward the end, of the pressure body 62 provided at the tip of the pushrod 61.
- the electromagnetic solenoid 60 When the internal combustion engine 10 is in a low-load operation state, the electromagnetic solenoid 60 is demagnetized to fit the connecting pin 56 only within the recess 52h so that the first intake rocker arm 51 and the second intake rocker arm 52 rock independently.
- the first intake rocker arm 51 is rocked by the first intake cam lobe 41i for the low-load operation region which has a small cam operating angle and a low cam nose.
- the intake valve 33 is driven to be opened and closed with a short valve-opening time period and a small lift for the low-load operation.
- the electromagnetic solenoid 60 When the internal combustion engine 10 shifts to a high-load operation state, the electromagnetic solenoid 60 is energized to cause the pushrod 61 to press the connecting pin 56 into the recess 51h against the urging force of the spring 54, so that the connecting pin 56 extends across both recesses 51h and 52h to integrally connect the first intake rocker arm 51 and the second intake rocker arm 52.
- the first intake rocker arm 51 rocks integrally with the second intake rocker arm 52 that is rocked by the second intake cam lobe 41ii for the high-load operation region which has a great cam operating angle and a high cam nose.
- the intake valve 33 By rocking of the first intake rocker arm 51 based on the second intake cam lobe 41ii, the intake valve 33 is driven to be opened and closed with a long valve-opening time period and a large lift for the high-load operation.
- the electromagnetic solenoid 60 is controlled by an ECU 70 serving as an engine control computer (see FIG. 3 ).
- the ECU 70 controls the movement of the pushrod 61 during connection and disconnection by the connecting pin 56 and performs duty control of the applied voltage of the electromagnetic solenoid 60 so as to prevent the generation of a hitting sound when the pushrod 61 stops.
- control of the electromagnetic solenoid 60 will be described with reference to control flowcharts shown in FIGs. 5 to 8 and the duty control voltage of the electromagnetic solenoid 60 as shown in FIGs. 9 and 10 .
- the ECU 70 determines the operating condition of the internal combustion engine 10 on the basis of an engine speed, a throttle opening, a vehicle speed or the like, and an engine temperature corresponding to the temperature of lubricating oil detected by the oil temperature sensor 27.
- the ECU 70 performs connection control of the electromagnetic solenoid 60.
- the ECU 70 performs disconnection control of the electromagnetic solenoid 60.
- step 1 the ECU 70 determines whether or not the internal combustion engine 10 is in the low-load condition. If the internal combustion engine 10 is in the low-load condition, the process goes to step 2. In step 2, the ECU 70 determines whether connection flag F is "1" or not. If the flag F is "1", the process goes to step 3. In step 3, the ECU 70 starts time measurement, and the process proceeds to a disconnection control routine of step 4. On the other hand, if the flag F is not "1" but "0", the process skips step 3 and proceeds to the disconnection control routine of step 4.
- connection flag F is set to "0" in step 5.
- connection flag F is "1".
- step 3 the time measurement is started, and the process proceeds to the disconnection control routine. And then the connection flag F becomes "0", and the process skips step 3 and proceeds to the disconnection control routine while the time measurement is running.
- step 1 if the ECU 70 determines that the internal combustion engine 10 is not in the low-load condition, that is, the internal combustion engine 10 is in the high-load condition, the process goes to step 6.
- step 6 the ECU 70 determines whether the connection flag F is "0" or not. If the flag F is "0”, the process goes to step 7.
- step 7 the ECU 70 starts time measurement, and the process proceeds to a connection control routine of step 8.
- the flag F is not "0" but "1"
- the process skips step 7 and proceeds to the connection control routine of step 8.
- connection flag F is set to "1" in step 9.
- connection flag F is "0".
- step 7 the time measurement is started, and the process proceeds to the connection control routine. And then the connection flag F becomes "1", and the process skips step 7 and proceeds to the connection control routine while the time measurement is running.
- the duty ratio Rd for maintaining the connected state in which the connecting pin 56 is inserted into the recess 51h against the urging force of the spring 54 to extend across both recesses 51h and 52h, is set as a connection maintaining duty ratio of b% (for example, 70%).
- step 4 The disconnection control routine of step 4 will be described with reference to an exemplary flowchart of FIG. 6 and the voltage duty control shown in FIG. 9(1) .
- the process proceeds to the disconnection control routine.
- the duty ratio Rd is b% and the first and second intake rocker arm 51 and 52 are in the connected state.
- step 3 When the time measurement is started (step 3) and the process proceeds to the disconnection control routine (step 4), the ECU 70 determines in step 11 of FIG. 6 whether or not measuring time t reaches t3 and determines in step 12 whether or not the measuring time t reaches time point t2 ( ⁇ t3). Initially, the measuring time t has not reached not only the time point t3 but also the time point t2, and therefore the process goes to step 13. In step 13, the ECU 70 sets the duty ratio Rd to c% ( ⁇ b%, for example, 50%) to decrease actual voltage and perform duty control of the electromagnetic solenoid 60 with a duty ratio Rd of c%.
- c% ⁇ b%, for example, 50%
- step 12 the process goes from step 12 to step 14, in which the ECU 70 sets the duty ratio Rd to d% ( ⁇ c%, for example, 30%) to further decrease the actual voltage and perform duty control of the electromagnetic solenoid 60 with a duty ratio Rd of d%.
- step 11 the process goes from step 11 to step 15, in which the ECU 70 sets the duty ratio Rd to zero to bring the electromagnetic solenoid 60 into a demagnetized state.
- FIG. 9(1) shows changes of the voltage duty control of the electromagnetic solenoid 60 in the above-described disconnection control.
- the duty ratio Rd is further decreased to d%.
- the duty ratio Rd is set to 0%. Therefore, the actual voltage shown by dashed lines decreases in a stepwise fashion from the connection maintaining voltage to zero.
- FIG 7 Another exemplary disconnection control is shown in a flowchart of FIG 7 .
- step 3 When, in the connected state of the first intake rocker arm 51 and the second intake rocker arm 52, the internal combustion engine 10 shifts from the high-load condition to the low-load condition, the time measurement is started (step 3) and the ECU 70 determines in step 21 whether or not the measuring time t reaches t3 and determines in step 22 whether or not the measuring time t reaches the time point t2 ( ⁇ t3). Initially, the measuring time t has not reached not only the time point t3 but also the time point t2, and therefore the process proceeds to step 23. In step 23, the ECU 70 sets the duty ratio Rd to 0% to demagnetize the electromagnetic solenoid 60.
- step 24 the ECU 70 energizes the electromagnetic solenoid 60 with the duty ratio Rd set to a brake duty ratio of b'% (for example, 60%) to brake the movement of the connecting pin 56 and the pushrod 61. Then when the measuring time t reaches the time point t3, the process goes from step 21 to step 25, in which the ECU 70 sets the duty ratio Rd to zero to demagnetize the electromagnetic solenoid 60.
- FIG. 9(2) shows changes of the voltage duty control of the electromagnetic solenoid 60 in the above-described disconnection control.
- the ECU 70 demagnetizes the electromagnetic solenoid 60 with the duty ratio Rd set to zero, so that the connecting pin 56 and the pushrod 61 move quickly with the urging force of the spring 54.
- the setting is made such that, at the time point t2, the electromagnetic solenoid 60 is energized with the brake duty ratio b'% to brake the movement of the connecting pin 56 and the pushrod 61, and, in the vicinity of the time point T3 at which the brake control ends, the connecting pin 56 comes out of the recess 51h.
- the movement speed just before the connecting pin 56 and the pushrod 61 stop can be easily reduced and the generation of a hitting sound can be prevented.
- the time point t2 to start the energization with the brake duty ratio b'% and the brake duty ratio b'% are preset to proper values. However, by previously obtaining and mapping optimum values of the time point t2 and the brake duty ratio b'% corresponding to oil temperature, it is possible to perform brake control with the optimum time point t2 and the optimum brake duty ratio b'% which correspond to oil temperature. Thus, the movement speed just before the pushrod 61 stops can be further reduced and the generation of a hitting sound can be prevented.
- time point t2 to start the energization with the brake duty ratio b'% for braking, a position where the pushrod 61 returns with the urging force of the spring 54 is detected by a position sensor, and a time point at which the pushrod 61 has returned to an optimum position for braking is detected.
- This time point may be set as the time point t2 to energize the electromagnetic solenoid 60 with the brake duty ratio b'%.
- connection control routine will be described with reference to an exemplary flowchart of FIG. 8 and the voltage duty control shown in FIG. 10 .
- the process proceeds to the connection control routine. Just before that, the duty ratio Rd is 0% and the first intake rocker arm 51 and the second intake rocker arm 52 are in the disconnected state.
- step 7 When the time measurement is started (step 7) and the process proceeds to the connection control routine (step 8), the ECU 70 determines in step 31 of FIG. 8 whether or not lubricating oil temperature (oil temperature) Yt detected by the oil temperature sensor 27 falls within a predetermined oil temperature range.
- the lubricating oil for smooth sliding of the connecting pin 56 becomes less viscous.
- the coil resistance of the electromagnetic solenoid 60 is small and the coil current flows through easily. For this reason, without change in applied voltage, the projecting force of the moving core member (61, 62) increases.
- a predetermined oil temperature range in which the movement speed is likely to increase is preset between approximately 60°C and 80°C, and duty control of the electromagnetic solenoid (60) is varied according to within and outside the predetermined oil temperature range.
- the predetermined oil temperature range is set to 60°C ⁇ Yt ⁇ 80°C.
- This predetermined oil temperature range is the temperature range in which vibration generated in the cylinder head becomes larger than that in other portions.
- step 31 the ECU 70 determines whether or not the oil temperature Yt falls within a predetermined oil temperature range (60°C ⁇ Yt ⁇ 80°C). If the ECU 70 determines that the oil temperature Yt falls outside the predetermined oil temperature range (Yt ⁇ 60°C, 80°C ⁇ Yt), the process goes to step 32. In step 32, the ECU 70 determines whether or not the measuring time t reaches predetermined time T that is sufficient to complete the connection. Initially, the measuring time t has not reached the predetermined time T, and therefore the process proceeds to step 33. In step 33, the ECU 70 determines whether subtraction counting value i is zero or not. If the subtraction counting value i is not zero, the process goes to step 34.
- a predetermined oil temperature range 60°C ⁇ Yt ⁇ 80°C.
- step 34 the ECU 70 sets the duty ratio Rd to a normal movement starting duty ratio of a% (for example, 90%) for starting the movement of the connecting pin 56 and starts duty control of the electromagnetic solenoid 60 with the duty ratio a% greater than the connection maintaining duty ratio b%, and energizes the electromagnetic solenoid 60 to cause the pushrod 61 to press the connecting pin 56 that is in position to release the connection.
- a% for example, 90%
- step 35 the ECU 70 subtracts 1 from the subtraction counting value i.
- the subtraction counting value i is initially set to initial value I (steps 39 and 41). When the subtraction counting value i becomes zero while steps 31 to 35 are repeated and duty control is performed with the normal movement starting duty ratio a%, the process skips over step 33 to step 36. In step 36, the ECU 70 determines whether another subtraction counting value j is zero or not.
- step 37 the ECU 70 sets the duty ratio Rd to the connection maintaining duty ratio b% to perform duty control, and in next step 38, subtracts 1 from the subtraction counting value j.
- the subtraction counting value j is initially set to initial value J (steps 39 and 41).
- the process skips over step 36 to step 39.
- the ECU 70 sets the subtraction counting values i and j to the initial value I and J, respectively.
- step 32 the process proceeds from step 32 to step 33, in which the duty control with the normal movement starting duty ratio a% and the duty control with the connection maintaining duty ratio b% are executed, and repeated until the measuring time t has reached the predetermined time T.
- step 40 the ECU 70 fixes the duty ratio Rd to the connection maintaining duty ratio b% for duty control, and in next step 41, reliably sets the subtraction counting values i and j to the initial value I and J, respectively.
- FIG. 10(1) shows changes of the voltage duty control of the electromagnetic solenoid 60 in the above-described connection control.
- the ECU 70 performs voltage duty control of the electromagnetic solenoid 60 with the duty ratio Rd set to the normal movement starting duty ratio a%, and starts the energization of the electromagnetic solenoid 60.
- the pushrod 61 applies a large pressure to the connecting pin 56.
- the ECU 70 decreases the duty ratio Rd to the connection maintaining duty ratio b%. Then at the time point t3 at which the subtraction counting value j becomes zero, the ECU 70 increases again the duty ratio Rd to the normal movement starting duty ratio a%.
- the duty controls with the normal movement starting duty ratio a% and the connection maintaining duty ratio b% are repeated until the predetermined time T. Therefore, as shown by dashed lines in FIG. 10(1) , the actual voltage repeats to turn from the normal movement starting voltage to the connection maintaining voltage, and, at the predetermined time T, is fixed to the connection maintaining voltage.
- the increase in the movement speed is adjusted by repeatedly changing a great pressure of the normal movement starting duty ratio a% at the start of the movement of the connecting pin 56 to a smaller pressure of the connection maintaining duty ratio b%, so that the connecting pin 56 can be stopped in a manner extending across both recesses 51h and 52h.
- the generation of vibration caused by pressing the spring 54 all the way in can be avoided.
- the duty control with the normal movement starting duty ratio a% is performed, thereby inserting the connecting pin 56 into the recess 51h and achieving connection. Also, the duty control with the connection maintaining duty ratio b% is performed, thereby maintaining the connection. Thus, the power consumption of the electromagnetic solenoid 60 can be reduced.
- step 31 if it is determined that the oil temperature Yt falls within the predetermined oil temperature range (60°C ⁇ Yt ⁇ 80°C), the process goes to step 42.
- steps 42 to 51 correspond to the above-described steps 32 to 41.
- the difference therebetween is in that, in step 44, the duty ratio Rd is set to a special movement starting duty ratio of a'% (for example, 80%) that is smaller than the normal movement starting duty ratio a% and greater than the connection maintaining duty ratio b%. As for the rest, the steps are the same.
- the ECU 70 energizes the electromagnetic solenoid 60 with the special movement starting duty ratio a'% that is smaller than the normal movement starting duty ratio a% and greater than the connection maintaining duty ratio b%, and controls the movement of the connecting pin 56. Then the ECU 70 drives the electromagnetic solenoid 60 while repeatedly performing control for changing to the connection maintaining duty ratio b% that is smaller than the special movement starting duty ratio a'%.
- the movement speed is adjusted to a value suitable for an oil temperature in the predetermined oil temperature range (60°C ⁇ Yt ⁇ 80°C) by repeatedly changing the pressure from a value smaller than normal of the special movement starting duty ratio a'% at the start of the movement of the connecting pin 56 to a smaller value of the connection maintaining duty ratio b%, so that the connecting pin 56 can be stopped in a manner extending across both recesses 51h and 52h.
- the generation of vibration caused by pressing the spring 54 all the way in can be avoided.
- the duty control with the special movement starting duty ratio a'% is performed, thereby inserting the connecting pin 56 into the recess 51h and connecting the first intake rocker arm 51 and the second intake rocker arm 52 together. Also, the duty control with the connection maintaining duty ratio b% is performed, thereby maintaining the connection. Thus, the power consumption of the electromagnetic solenoid 60 can be reduced.
- the predetermined oil temperature range is set to 60°C ⁇ Yt ⁇ 80°C, which is an optimum range.
- the lower limit is not limited to 60°C, but also can be set to an oil temperature of around 60°C.
- the upper limit is not limited to 80°C, but also can be set to an oil temperature of around 80°C.
- the special movement starting duty ratio a'% is set, as the duty ratio Rd that permits the start of movement of the connecting pin 56, to a predetermined constant value that is smaller than the normal movement starting duty ratio a% and greater than the connection maintaining duty ratio b%.
- the optimum special movement starting duty ratio a'% may be previously obtained and mapped corresponding to oil temperature (such a map that the higher the oil temperature, the smaller the special movement starting duty ratio a'%).
- the movement speed is adjusted to a value more suitable for oil temperature by determining the special movement starting duty ratio a'% in accordance with oil temperature, so that the connecting pin 56 can be stopped in a connecting position.
- the correlation of the normal movement starting duty ratio a and the special movement starting duty ratio a'% with oil temperature may be previously obtained and mapped.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Valve Device For Special Equipments (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
- Output Control And Ontrol Of Special Type Engine (AREA)
Description
- The present invention relates to a variable valve train for an internal combustion engine.
- As an example of the variable valve trains in which rocker arms journaled coaxially with and adjacent to each other are connected or disconnected by movement of a connecting pin, thereby allowing changes in the lift and valve timing of an intake valve, the case where an electromagnetic solenoid is used as an actuator for moving the connecting pin is found in an earlier application filed by the same applicant (see Patent Literature 1).
- [Patent Literature 1]
JP-A No. 2012-036877 - The variable valve train disclosed in the
Patent Literature 1 has a structure in which the connecting pin for connecting the adjacent rocker arms together is urged from one side by a spring and pressed from the other side by a moving core of the electromagnetic solenoid. - When the electromagnetic solenoid is energized, the moving core is protruded to move the connecting pin against the action of the spring, thereby connecting the rocker arms together. When the electromagnetic solenoid is demagnetized, the connecting pin is forced back by the spring, thereby disconnecting the rocker arms from each other.
- The
Patent Literature 1 discloses no controls over the electromagnetic solenoid other than that described above. - During the time the rocker arms are in the connected state, it is necessary to maintain the state after moving the connecting pin against the action of the spring. Therefore, a large amount of power is required to constantly energize the electromagnetic solenoid, leading to an increase in size of a battery.
- It should be noted that unlike hydraulic pressure, the electromagnetic solenoid produces less pressure, and therefore a larger amount of power is required to maintain the connected state.
- Furthermore, when the electromagnetic solenoid is demagnetized and the connection between both rocker arms is released, the demagnetization of the electromagnetic solenoid causes the connecting pin and the moving core to return quickly with the urging force of the spring. Therefore, especially when the moving core is separated from the connecting pin and then further moved by inertia, the moving core is brought into abutting contact with the equivalent of a stopper in the electromagnetic solenoid, which might create a hitting sound.
- Document
EP 1736 639 A2 shows a valve actuation device for an internal combustion engine which comprises a cam shaft having thereon at least first and second cams that are different in profile, a first rocker arm that is in contact with the first cam to be swung, the first rocker arm being adapted to actuate an engine valve, a second rocker arm that is in contact with the second cam to be swung, a coupling mechanism that selectively couples and uncouples the first and second rocker arms, and an electric actuating mechanism that actuates the coupling mechanism with an electric power for the selective coupling and uncoupling. - Document
US 2001/0271918 A1 shows a changeover mechanism which is capable of switching between a connection state in which a first rocker arm and a second rocker arm are in connection with each other via a changeover pin and a disconnection state in which the connection is released. The changeover mechanism performs energization of actuators for each cylinder in a case in which fuel supply to the internal combustion engine is stopped in response to an establishment of a predetermined stop condition. The above-described energization of the actuator for each cylinder is stopped in a case in which a crankshaft of the internal combustion engine stops rotating during an energization time period of the actuator and in which the crankshaft is not driven by an external power. - Accordingly, the present invention has been made in view of the foregoing, and an object of the present invention is to provide a variable valve train for an internal combustion engine which duty controls an electromagnetic solenoid for moving a connecting pin, thereby reducing the power consumption of the electromagnetic solenoid and preventing the generation of a hitting sound while preventing an increase in the temperature of the electromagnetic solenoid.
- In order to accomplish the above-mentioned object, the present invention, according to a feature of the invention described in
Claim 1, provides a variable valve train for an internal combustion engine in which: - rocker arms (51,52) journaled coaxially with and adjacent to each other rock in contact with cam lobes (41i, 41ii) having different profiles of a camshaft, and an intake valve (33) is opened and closed by rocking of one rocker arm (51) of the rocker arms;
- a connecting pin (56) urged by a spring (54) moves between respective hole portions (51h, 52h) formed in the rocker arms (51, 52), thereby enabling a connection between the rocker arms (51,52);
- the connecting pin (56) is moved by forward and backward movement of a moving core member (61, 62) of an electromagnetic solenoid (60); and
- control means (70) energizes the electromagnetic solenoid (60) to cause the moving core member (61, 62) to protrude, and thereby the connecting pin (56) to move against urging force of the spring (54) so that the rocker arms (51, 52) are connected together and integrally rocked,
- wherein the control means (70) duty controls the electromagnetic solenoid (60) and drives the moving core member (61, 62).
- A further feature of the invention described in
Claim 1 is that,
in a disconnected state of the rocker arms (51, 52) in which the connecting pin (56) is fitted in the other hole portion (52h) of the hole portions to allow the rocker arms (51,52) to rock independently, from a demagnetized state of the electromagnetic solenoid (60), the control means (70) duty controls the electromagnetic solenoid (60) with a normal movement starting duty ratio (a) that causes the connecting pin (56) to start to move against urging force of the spring (54), and then duty controls the electromagnetic solenoid (60) with a connection maintaining duty ratio (b) smaller than the normal movement starting duty ratio (a) to insert the connecting pin (56) into one hole portion (51h) of the hole portions so that the connecting pin (56) extends across both hole portions (51h, 52h), thereby connecting the rocker arms (51,52) together. - A feature of the invention described in
Claim 2 is that,
in the variable valve train for the internal combustion engine described inClaim 1,
a process of duty controlling the electromagnetic solenoid (60) with the normal movement starting duty ratio (a) and then duty controlling the electromagnetic solenoid (60) with the connection maintaining duty ratio (b) is repeated multiple times. - A feature of the invention described in
Claim 3 is that
the variable valve train for the internal combustion engine described inClaim 2,
further includes oil temperature detecting means (27) for detecting temperature of lubricating oil of the internal combustion engine (10). - The control means (70) presets a predetermined oil temperature range of approximately 60°C to 80°C.
- When an oil temperature detected by the oil temperature detecting means (27) falls outside the predetermined oil temperature range, the control means (70) repeats multiple times the process of duty controlling the electromagnetic solenoid (60) with the normal movement starting duty ratio (a) that causes the connecting pin (56) to start to move against urging force of the spring (54), and then duty controlling the electromagnetic solenoid (60) with the connection maintaining duty ratio (b) smaller than the normal movement starting duty ratio (a).
- When the oil temperature detected by the oil temperature detecting means (27) falls within the predetermined oil temperature range, the control means (70) repeats multiple times a process of controlling movement of the connecting pin (56) with a special movement starting duty ratio (a') smaller than the normal movement starting duty ratio (a) and greater than the connection maintaining duty ratio (b), and then duty controlling the electromagnetic solenoid (60) with the connection maintaining duty ratio (b).
- A feature of the invention described in
Claim 4 is that,
in the variable valve train for the internal combustion engine described inClaim 3,
the predetermined oil temperature range is a temperature range in which vibration generated in a cylinder head becomes larger than in other portions. - A feature of the invention described in
Claim 5 is that,
in the variable valve train for the internal combustion engine described inClaims
the normal movement starting duty ratio (a) and the special movement starting duty ratio (a') are determined from a map correlated with an oil temperature value. - A feature of the invention described in Claim 6 is that,
in the variable valve train for the internal combustion engine described in any one ofClaims 1 to 5,
the control means (70) performs control to decrease the duty ratio in a stepwise fashion from the connection maintaining duty ratio (b) that maintains the connected state of the rocker arms (51, 52) by causing the connecting pin (56) to extend across both hole portions (51h, 52h), and adjusts movement speed of the moving core member (61, 62) to stop the moving core member (61, 62), thereby releasing the connection between the rocker arms (51, 52). - A feature of the invention described in Claim 7 is that,
in the variable valve train for the internal combustion engine described in any one ofClaims 1 to 5,
the control means (70) changes the duty ratio to zero from the connection maintaining duty ratio (b) that maintains the connected state of the rocker arms (51, 52) by causing the connecting pin (56) to extend across both hole portions (51h, 52h), and then controls the duty ratio to a brake duty ratio (b') at a predetermined timing so that the moving core member (61,62) is reduced in movement speed and stopped, thereby releasing the connection between the rocker arms (51, 52). - A feature of the invention described in Claim 8 is that,
in the variable valve train for the internal combustion engine described in Claim 7,
the brake duty ratio (b') is determined from the map correlated with the oil temperature value. - A feature of the invention described in Claim 9 is that,
in the variable valve train for the internal combustion engine described in Claim 7,
a position of the moving core member (61, 62) is detected by a position sensor, and at a predetermined position, control is performed with the brake duty ratio (b') so that the moving core member (61, 62) is reduced in movement speed and stopped, thereby releasing the connection between the rocker arms (51,52). - According to the variable valve train for the internal combustion engine described in
Claim 1, the control means (70) duty controls the electromagnetic solenoid (60) and drives the moving core member (61,62). Thus, since the duty control is also performed when the connection is maintained, the power consumption of the electromagnetic solenoid (60) can be reduced. - Furthermore, the movement speed of the moving core member (61,62) before stopped is reduced, and thus the generation of a hitting sound due to abutting contact of the moving core member (61, 62) with the equivalent of a stopper can be prevented.
- Moreover, from a demagnetized state of the electromagnetic solenoid (60), the control means (70) duty controls the electromagnetic solenoid (60) with the normal movement starting duty ratio (a) that causes the connecting pin (56) to start to move against urging force of the spring (54), and then duty controls the electromagnetic solenoid (60) with the connection maintaining duty ratio (b) smaller than the normal movement starting duty ratio (a). A great pressure of the normal movement starting duty ratio (a) at the start of the movement of the connecting pin (56) forces the connecting pin (56) into the one hole portion (51h) to cause the connecting pin (56) to extend across both hole portions (51h, 52h), thereby allowing the connection between the rocker arms (51, 52). Thereafter, the connection can be maintained by the connection maintaining duty ratio (b) smaller than the normal movement starting duty ratio (a). Thus, the power consumption of the electromagnetic solenoid can be reduced. Also, when the movement speed of the connecting pin (56) is adjusted to stop the connecting pin (56), the generation of vibration caused by pressing the spring (54) all the way in can be avoided.
- According to the variable valve train for the internal combustion engine described in
Claim 2, the control means (70) repeats multiple times the process of duty controlling the electromagnetic solenoid (60) with the normal movement starting duty ratio (a), and then duty controlling the electromagnetic solenoid (60) with the connection maintaining duty ratio (b). Thus, even if the connecting pin (56) comes out of the one hole portion (51h), duty control is repeatedly performed with the normal movement starting duty ratio (a) so that the connecting pin (56) is inserted into the hole portion (51h). Thus the connected state can be ensured. Also, since the connection is finally maintained with the small connection maintaining duty ratio (b), the power consumption of the electromagnetic solenoid can be also reduced. - According to the variable valve train for the internal combustion engine described in
Claim 3, when the engine temperature (oil temperature) of the internal combustion engine increases and the temperature of lubricating oil is greater than about 60°C, the lubricating oil for smooth sliding of the connecting pin (56) becomes less viscous. Also, when the oil temperature is smaller than about 80°C, the coil resistance of the electromagnetic solenoid is small and the coil current flows through easily, so that the projecting force of the moving core member (61, 62) increases. Thus, when the electromagnetic solenoid is energized in the oil temperature range of approximately 60°C to 80°C, the movement speed of the connecting pin (56) is likely to increase, and the connecting pin (56) is not smoothly stopped, thereby making the generation of vibration more likely. Therefore, the predetermined oil temperature range is preset between approximately 60°C and 80°C, and duty control of the electromagnetic solenoid (60) is varied according to within and outside the predetermined oil temperature range. - More specifically, when the oil temperature falls outside the predetermined oil temperature range, the control means (70) repeats multiple times the process of duty controlling the electromagnetic solenoid (60) with the normal movement starting duty ratio (a), and then duty controlling the electromagnetic solenoid (60) with the connection maintaining duty ratio (b) smaller than the normal movement starting duty ratio (a). Thus, the increase in the movement speed is adjusted by repeatedly changing a great pressure of the normal movement starting duty ratio (a) at the start of the movement of the connecting pin (56) to a smaller pressure of the connection maintaining duty ratio (b), so that the connecting pin (56) can be stopped in a manner extending across both hole portions (51h, 52h). Thus, the generation of vibration caused by pressing the spring (54) all the way in can be avoided.
- When an oil temperature falls within the predetermined oil temperature range, the movement speed of the connecting pin (56) is likely to increase. Therefore, the control means (70) repeats multiple times a process of duty controlling the electromagnetic solenoid (60) with a special movement starting duty ratio (a') smaller than the normal movement starting duty ratio (a) and greater than the connection maintaining duty ratio (b), and then duty controlling the electromagnetic solenoid (60) with the connection maintaining duty ratio (b) smaller than the special movement starting duty ratio (a'). Thus, the pressure change from a value smaller than normal of the special movement starting duty ratio (a') at the start of the movement of the connecting pin (56) to a smaller value of the connection maintaining duty ratio (b) is repeated. Thus, the movement speed is adjusted to a value suitable for the oil temperature within the predetermined oil temperature range so that the connecting pin (56) can be stopped in a manner extending across both hole portions (51h, 52h).
- In both cases where the oil temperature falls within and outside the predetermined oil temperature range, since the connection is finally maintained with the small connection maintaining duty ratio (b), the power consumption of the electromagnetic solenoid can be also reduced.
- Also, even if the connecting pin (56) fails to be inserted into the hole portion (51h) on the first time and the connection does not succeed, duty control with the normal movement starting duty ratio (a) or the special movement starting duty ratio (a') is repeated so that the connecting pin (56) is inserted into the hole portion (51h). Thus, the connected state can be ensured.
- According to the variable valve train for the internal combustion engine described in
Claim 4, the predetermined oil temperature range is a temperature range in which vibration generated in the cylinder head becomes larger than in other portions. Thus, the insertion duty corresponding to the speed of the connecting pin (56) is applied by the oil temperature, thereby reducing the generation of a hitting sound. - According to the variable valve train for the internal combustion engine described in
Claim 5, the movement normal starting duty ratio (a) and the special movement starting duty ratio (a') are determined from a map correlated with an oil temperature value. Thus, the speed of the moving core member (61, 62) is properly changed depending on the temperature state of the internal combustion engine (more specifically, the change in resistance of the electromagnetic solenoid or in viscosity of lubricating oil with temperature), thereby reducing the generation of a hitting sound. - According to the variable valve train for the internal combustion engine described in Claim 6, the control means (70) performs control to decrease the duty ratio in a stepwise fashion from the connection maintaining duty ratio (b) that maintains the connected state of the rocker arms (51,52) by causing the connecting pin (56) to extend across both hole portions (51h, 52h), and adjusts movement speed of the moving core member (61,62) to stop the moving core member (61, 62), thereby releasing the connection between the rocker arms (51,52). Thus, the movement speed of the moving core member (61, 62) just before stopped can be easily reduced, and the generation of a hitting sound can be prevented.
- According to the variable valve train for the internal combustion engine described in Claim 7, the control means (70) changes the duty ratio to zero from the connection maintaining duty ratio (b) that maintains the connected state of the rocker arms (51, 52) by causing the connecting pin (56) to extend across both hole portions (51h, 52h), and then controls the duty ratio to a brake duty ratio (b') at a predetermined timing so that the moving core member (61, 62) is reduced in movement speed and stopped, thereby releasing the connection between the rocker arms (51, 52). Thus, the movement speed of the moving core member (61, 62) is reduced by the duty control with the duty ratio to a brake duty ratio (b'), thereby allowing an easy reduction in movement speed of the moving core member (61, 62) just before stopped and the prevention of generation of a hitting sound.
- According to the variable valve train for the internal combustion engine described in Claim 8, the brake duty ratio (b') is determined from the map correlated with the oil temperature value. Thus, the moving core member (61,62) is properly braked depending on the temperature state of the internal combustion engine (more specifically, the change in resistance of the electromagnetic solenoid or in viscosity of lubricating oil with temperature), thereby reducing the generation of a hitting sound.
- According to the variable valve train for the internal combustion engine described in Claim 9, the position of the moving core member (61, 62) is detected by the position sensor, and at a predetermined position, control is performed with the brake duty ratio (b') so that the moving core member (61, 62) is reduced in movement speed and stopped, thereby releasing the connection between the rocker arms (51,52). Thus, the moving core member (61, 62) is properly braked and the generation of a hitting sound is reduced.
-
- [
FIG. 1] FIG. 1 is a partial side view of a motorcycle mounted with an internal combustion engine in accordance with an embodiment of the present invention. - [
FIG. 2] FIG. 2 is a longitudinal sectional view of the internal combustion engine. - [
FIG. 3] FIG. 3 is a top plan view of a cylinder head, showing a valve operating mechanism of the internal combustion engine. - [
FIG. 4] FIG. 4 is a sectional view taken along line IV-IV ofFIG. 2 . - [
FIG. 5] FIG. 5 is a flowchart of a main control routine of an electromagnetic solenoid. - [
FIG. 6] FIG. 6 is a flowchart of a disconnection control routine. - [
FIG. 7] FIG. 7 is a flowchart of another disconnection control routine. - [
FIG. 8] FIG. 8 is a flowchart of a connection control routine. - [
FIG. 9] FIG. 9 is a graph showing changes of voltage duty control of the electromagnetic solenoid in the disconnection control routine. - [
FIG. 10] FIG. 10 is a graph showing changes of voltage duty control of the electromagnetic solenoid in the connection control routine. - Hereinafter, an embodiment of the present invention will be described with reference to
FIGs. 1 to 10 . -
FIG. 1 shows a partial side view of amotorcycle 1 mounted with aninternal combustion engine 10 in accordance with this embodiment. - The
motorcycle 1 includes theinternal combustion engine 10 that is suspended through mounting members from a pair of left and rightmain frames 3 extending rearwardly from ahead pipe 2 and bent obliquely downward halfway along its length, and downframes 4 extending obliquely rearward and downward from thehead pipe 2. - The
internal combustion engine 10 is the SOHC, two-valve, air-cooled single-cylinder four-strokeinternal combustion engine 10. Theinternal combustion engine 10 is composed of acylinder block 12, acylinder head 13, and acylinder head cover 14 sequentially superposed above acrankcase 11 that journals acrankshaft 25. Theinternal combustion engine 10 is provided to stand in a forward-leaning position. - An
intake pipe 15 extends from a rear surface of thecylinder head 13 through a connectingpipe 15c and is connected to anair cleaner 17 through athrottle body 16. - A
fuel injection valve 20 is attached to the intake pipe 15 (seeFIG. 2 ). - An
exhaust pipe 18 extending from a front surface of thecylinder head 13 is bent downward and extends rearwardly along the lower surface from the front of thecrankcase 11 to be connected to amuffler 19. - Referring to
FIG. 2 , apiston 21 is fitted in acylinder bore 12b of thecylinder block 12 of theinternal combustion engine 10 in such a manner that thepiston 21 can reciprocate and slide therein. Thepiston 21 is connected to thecrankshaft 25 by a connectingrod 22 to constitute a crank mechanism. - A
combustion chamber 30, facing thepiston 21, is formed within thecylinder head 13 in position to correspond thecylinder bore 12b. Anintake port 31 extends rearwardly from thecombustion chamber 30, and anexhaust port 32 extends forwardly from the combustion chamber 30 (seeFIG. 2 ). Theintake pipe 15 is connected to theintake port 31, and theexhaust pipe 18 is connected to theexhaust port 32. - A
spark plug 26 is mounted in a ceiling wall of thecombustion chamber 30, with its tip facing the combustion chamber 30 (seeFIG. 4 ). - As shown in
FIG. 2 , anintake valve 33 and anexhaust valve 34 are slidably supported by their respective valve guides that are integrally fitted into thecylinder head 13. Theintake valve 33 and theexhaust valve 34 are upwardly urged by anintake valve spring 35 and anexhaust valve spring 36, respectively, so as to close an intake valve opening of theintake port 31 and an exhaust valve opening of theexhaust port 32, the intake and exhaust valve openings facing thecombustion chamber 30. Theintake valve 33 and theexhaust valve 34 are pressed from above in synchronism with the rotation of thecrankshaft 25 by avariable valve train 40 formed above thecylinder head 13, so as to open the intake and exhaust valve openings. - The
variable valve train 40 is formed with left and right opposedcamshaft receiving walls camshaft receiving walls bottom wall 13b inside thecylinder head 13, surrounded by aperipheral wall 13a of thecylinder head 13. Acamshaft 41, oriented in the left-right direction, is rotatably journaled to the left and rightcamshaft receiving walls bearings - The
camshaft 41 protrudes leftward through the leftcamshaft receiving wall 13L, and its protruding portion is mounted with achain sprocket 44. - A
chain 45 extends between thechain sprocket 44 and a chain sprocket (not shown) fitted into thecrankshaft 25. Thecamshaft 41 rotates at a rotational speed of one-half that of thecrankshaft 25. - A chain opening 13h through the cam chamber
bottom wall 13b is formed on the left side of the leftcamshaft receiving wall 13L. Thechain 45 wrapped around thechain sprocket 44 passes through thechain opening 13h and extends downward, and then passes through achain chamber 12h of thecylinder block 12 to be wrapped around the chain sprocket fitted into thecrankshaft 25 in thecrankcase 11. - It should be noted that, as shown in
FIG. 3 , anoil storage recess 13d recessed downward is formed in the cam chamberbottom wall 13b of thecylinder head 13 at the rear of thechain opening 13h. Asensing portion 27a at the tip of anoil temperature sensor 27 installed from the outside in a rear wall of theperipheral wall 13a of thecylinder head 13 is protruded into theoil storage recess 13d so that theoil temperature sensor 27 can detect the temperature of lubricating oil in theoil storage recess 13d. - Between the left and right
camshaft receiving walls rocker arm shaft 47 is disposed above and obliquely rearward of thecamshaft 41, and an exhaustrocker arm shaft 48 is disposed above and obliquely forward of thecamshaft 41. A firstintake rocker arm 51 and a secondintake rocker arm 52 adjacent to each other are rockably journaled to the intakerocker arm shaft 47. Anexhaust rocker arm 53 is rockably journaled to the exhaustrocker arm shaft 48. - The first
intake rocker arm 51 has a roller 51r at an end thereof toward thecamshaft 41, and the roller 51r is in contact with a firstintake cam lobe 41i of thecamshaft 41. The firstintake rocker arm 51 has an adjustingscrew 51s at the other end thereof, and the adjustingscrew 51s is in contact with the upper end of a valve stem of theintake valve 33. - The second
intake rocker arm 52 has aroller 52r at an end thereof toward thecamshaft 41, and theroller 52r is in contact with a second intake cam lobe 41ii of thecamshaft 41. Theother end 52a of the secondintake rocker arm 52 is in contact with the upper end of alifter 38 received in a receiving recess 13bd formed in the cam chamberbottom wall 13b, thelifter 38 being urged by a coil spring 37 (seeFIG. 2 ). - The first
intake cam lobe 41i and the second intake cam lobe 41ii have different profiles. The firstintake cam lobe 41i and the second intake cam lobe 41ii have cam noses that protrude in the same direction from respective base circles of the same diameter. The second intake cam lobe 41ii for a high-load operation region has a higher cam nose and a greater cam operating angle than those of the firstintake cam lobe 41i for a low-load operation region. - On the other hand, the
exhaust rocker arm 53 has a roller 53r at an end thereof toward thecamshaft 41, and the roller 51r is in contact with anexhaust cam lobe 41e of thecamshaft 41. Theexhaust rocker arm 53 has an adjustingscrew 53s at the other end thereof, and the adjustingscrew 51s is in contact with the upper end of a valve stem of theexhaust valve 34. - The first
intake rocker arm 51 and the secondintake rocker arm 52 respectively have protrudingportions portions recesses recesses portions - Inside the
recess 51h of the firstintake rocker arm 51 located on the left side, aspring 54 is interposed and a bottomedcylindrical plunger 55 is inserted. Theplunger 55 is urged by thespring 54 toward the protrudingportion 52a of the secondintake rocker arm 52 located in a right direction. - The
recess 52h of the secondintake rocker arm 52 located on the right side has a circular hole bored in a bottom wall of therecess 52h, that is, the right sidewall. A connectingpin 56 is fitted within therecess 52h. Anextension rod 56b extending to the right of the connectingpin 56 protrudes through the circular hole in the bottom wall of therecess 52h. - As shown in
FIGs. 3 and4 , when the connectingpin 56 is pressed by theplunger 55 urged by thespring 54, and completely fitted within therecess 52h, the left end surface of the connectingpin 56 is flush with the adjacent surfaces of the protrudingportions intake rocker arms pin 56 is fitted only within therecess 52h, and consequently the firstintake rocker arm 51 and the secondintake rocker arm 52 can rock independently. - It is to be noted that, if the
recesses intake rocker arm 51 and the secondintake rocker arm 52 rock independently, as shown inFIGs. 3 and4 , the connectingpin 56 is urged by thespring 54 and fitted only within therecess 52h, so that the left end surface of the connectingpin 56 is kept flush with the adjacent surfaces of the protrudingportions recesses pin 56 is brought into contact with the adjacent surface of the protrudingportion 51a of the firstintake rocker arm 51, so that the left end surface of the connectingpin 56 is kept flush with the adjacent surface of the protrudingportion 51a. - The
plunger 55 is also urged by thespring 54 into contact with the adjacent surface of the protrudingportion 52a of the secondintake rocker arm 52, so that theplunger 55 is kept flush with the adjacent surface of the protrudingportion 52a. - The
cylinder head 13 and thecylinder head cover 14 are joined together with theperipheral wall 13a of thecylinder head 13 and aperipheral wall 14a of thecylinder head cover 14 mating with each other. Anelectromagnetic solenoid 60 is mounted from the outside at the level of right-hand mating faces of theperipheral walls - A
pushrod 61 serving as a moving core of theelectromagnetic solenoid 60 protrudes leftward through the right-hand mating faces of theperipheral walls pushrod 61 is mounted at the tip thereof with ametallic pressure body 62. - The
pushrod 61 protrudes toward the protrudingportion 52a of the secondintake rocker arm 52. The right end of theextension rod 56b of the connectingpin 56 protruding from the protrudingportion 52a of the secondintake rocker arm 52 is in contact with the end surface of an end diameter-increasedportion 62b, increased in diameter toward the end, of thepressure body 62 provided at the tip of thepushrod 61. - When the
electromagnetic solenoid 60 is in a demagnetized state, as shown by the solid lines inFIGs. 3 and4 , the connectingpin 56 urged by thespring 54 is fitted only within therecess 52h, so that the firstintake rocker arm 51 and the secondintake rocker arm 52 rock independently. - When the
electromagnetic solenoid 60 is energized, a leftward projecting force acts on thepushrod 61, thereby pressing the connectingpin 56 leftward through thepressure body 62. Thus, when therecesses portions intake rocker arms pin 56 is inserted into therecess 51h while forcing theplunger 55 into therecess 51h of the firstintake rocker arm 51 against the urging force of thespring 54, so that the connectingpin 56 extends across bothrecesses FIGs. 3 and4 ). Consequently, the firstintake rocker arm 51 and the secondintake rocker arm 52 are connected by the connectingpin 56 to be integrally rocked. - When the
internal combustion engine 10 is in a low-load operation state, theelectromagnetic solenoid 60 is demagnetized to fit the connectingpin 56 only within therecess 52h so that the firstintake rocker arm 51 and the secondintake rocker arm 52 rock independently. The firstintake rocker arm 51 is rocked by the firstintake cam lobe 41i for the low-load operation region which has a small cam operating angle and a low cam nose. By rocking of the firstintake rocker arm 51 based on the firstintake cam lobe 41i, theintake valve 33 is driven to be opened and closed with a short valve-opening time period and a small lift for the low-load operation. - When the
internal combustion engine 10 shifts to a high-load operation state, theelectromagnetic solenoid 60 is energized to cause thepushrod 61 to press the connectingpin 56 into therecess 51h against the urging force of thespring 54, so that the connectingpin 56 extends across bothrecesses intake rocker arm 51 and the secondintake rocker arm 52. Thus, the firstintake rocker arm 51 rocks integrally with the secondintake rocker arm 52 that is rocked by the second intake cam lobe 41ii for the high-load operation region which has a great cam operating angle and a high cam nose. By rocking of the firstintake rocker arm 51 based on the second intake cam lobe 41ii, theintake valve 33 is driven to be opened and closed with a long valve-opening time period and a large lift for the high-load operation. - The
electromagnetic solenoid 60 is controlled by anECU 70 serving as an engine control computer (seeFIG. 3 ). TheECU 70 controls the movement of thepushrod 61 during connection and disconnection by the connectingpin 56 and performs duty control of the applied voltage of theelectromagnetic solenoid 60 so as to prevent the generation of a hitting sound when thepushrod 61 stops. - Hereinafter, control of the
electromagnetic solenoid 60 will be described with reference to control flowcharts shown inFIGs. 5 to 8 and the duty control voltage of theelectromagnetic solenoid 60 as shown inFIGs. 9 and10 . - The
ECU 70 determines the operating condition of theinternal combustion engine 10 on the basis of an engine speed, a throttle opening, a vehicle speed or the like, and an engine temperature corresponding to the temperature of lubricating oil detected by theoil temperature sensor 27. When the operating condition shifts from the low-load condition to the high-load condition, theECU 70 performs connection control of theelectromagnetic solenoid 60. When the operating condition shifts from the high-load condition to the low-load condition, on the other hand, theECU 70 performs disconnection control of theelectromagnetic solenoid 60. - Referring to the flowchart of
FIG. 5 showing a main control routine of theelectromagnetic solenoid 60, firstly, instep 1, theECU 70 determines whether or not theinternal combustion engine 10 is in the low-load condition. If theinternal combustion engine 10 is in the low-load condition, the process goes to step 2. Instep 2, theECU 70 determines whether connection flag F is "1" or not. If the flag F is "1", the process goes to step 3. Instep 3, theECU 70 starts time measurement, and the process proceeds to a disconnection control routine ofstep 4. On the other hand, if the flag F is not "1" but "0", the process skipsstep 3 and proceeds to the disconnection control routine ofstep 4. - Once the process proceeds to the disconnection control routine, the connection flag F is set to "0" in
step 5. - More specifically, when the
internal combustion engine 10 shifts from the high-load condition to the low-load condition, the connection flag F is "1". Instep 3, the time measurement is started, and the process proceeds to the disconnection control routine. And then the connection flag F becomes "0", and the process skipsstep 3 and proceeds to the disconnection control routine while the time measurement is running. - Also, in
step 1, if theECU 70 determines that theinternal combustion engine 10 is not in the low-load condition, that is, theinternal combustion engine 10 is in the high-load condition, the process goes to step 6. In step 6, theECU 70 determines whether the connection flag F is "0" or not. If the flag F is "0", the process goes to step 7. In step 7, theECU 70 starts time measurement, and the process proceeds to a connection control routine of step 8. On the other hand, if the flag F is not "0" but "1", the process skips step 7 and proceeds to the connection control routine of step 8. - Once the process proceeds to the connection control routine, the connection flag F is set to "1" in step 9.
- More specifically, when the
internal combustion engine 10 shifts from the low-load condition to the high-load condition, the connection flag F is "0". In step 7, the time measurement is started, and the process proceeds to the connection control routine. And then the connection flag F becomes "1", and the process skips step 7 and proceeds to the connection control routine while the time measurement is running. - Here, when PWM duty control is executed and disconnection is performed, the
electromagnetic solenoid 60 is in a demagnetized state and duty ratio Rd is 0%. - The duty ratio Rd for maintaining the connected state, in which the connecting
pin 56 is inserted into therecess 51h against the urging force of thespring 54 to extend across bothrecesses - The disconnection control routine of
step 4 will be described with reference to an exemplary flowchart ofFIG. 6 and the voltage duty control shown inFIG. 9(1) . - When shifting from the high-load condition to the low-load condition, the process proceeds to the disconnection control routine. However, just before the process proceeds to the disconnection control routine, the duty ratio Rd is b% and the first and second
intake rocker arm - When the time measurement is started (step 3) and the process proceeds to the disconnection control routine (step 4), the
ECU 70 determines instep 11 ofFIG. 6 whether or not measuring time t reaches t3 and determines instep 12 whether or not the measuring time t reaches time point t2 (<t3). Initially, the measuring time t has not reached not only the time point t3 but also the time point t2, and therefore the process goes to step 13. Instep 13, theECU 70 sets the duty ratio Rd to c% (<b%, for example, 50%) to decrease actual voltage and perform duty control of theelectromagnetic solenoid 60 with a duty ratio Rd of c%. - And then when the measuring time t reaches the time point t2, the process goes from
step 12 to step 14, in which theECU 70 sets the duty ratio Rd to d% (<c%, for example, 30%) to further decrease the actual voltage and perform duty control of theelectromagnetic solenoid 60 with a duty ratio Rd of d%. - Thereafter, when the measuring time t reaches the time point t3, the process goes from
step 11 to step 15, in which theECU 70 sets the duty ratio Rd to zero to bring theelectromagnetic solenoid 60 into a demagnetized state. -
FIG. 9(1) shows changes of the voltage duty control of theelectromagnetic solenoid 60 in the above-described disconnection control. - The duty ratio Rd is decreased to c% at time point t1 (corresponding to the time measurement starting point, t=0) at which the
internal combustion engine 10 shifts to the low-load condition from the state in which the firstintake rocker arm 51 and the secondintake rocker arm 52 are integrally connected by duty controlling theelectromagnetic solenoid 60 with the connection maintaining duty ratio b% in the high-load condition and inserting the connectingpin 56 into therecess 51h to cause the connectingpin 56 to extend across bothrecesses - Consequently, the pressure to insert the connecting
pin 56 into therecess 51h decreases in a stepwise fashion. Thus, the connectingpin 56 and thepushrod 61 are moved by the urging force of thespring 54 while being decelerated, and finally the connectingpin 56 comes out of therecess 51h, thereby releasing the connection between the firstintake rocker arm 51 and the secondintake rocker arm 52. - Since the connecting
pin 56 comes completely out of therecess 51h in the vicinity of the time point t3, the movement speed just before thepushrod 61 stops can be easily reduced and the generation of a hitting sound can be prevented. - Furthermore, another exemplary disconnection control is shown in a flowchart of
FIG 7 . - When, in the connected state of the first
intake rocker arm 51 and the secondintake rocker arm 52, theinternal combustion engine 10 shifts from the high-load condition to the low-load condition, the time measurement is started (step 3) and theECU 70 determines instep 21 whether or not the measuring time t reaches t3 and determines instep 22 whether or not the measuring time t reaches the time point t2 (<t3). Initially, the measuring time t has not reached not only the time point t3 but also the time point t2, and therefore the process proceeds to step 23. In step 23, theECU 70 sets the duty ratio Rd to 0% to demagnetize theelectromagnetic solenoid 60. And then when the measuring time t reaches the time point t2 that falls considerably short of the time point at which the connectingpin 56 comes out of therecess 51h, the process goes fromstep 22 to step 24. In step 24, theECU 70 energizes theelectromagnetic solenoid 60 with the duty ratio Rd set to a brake duty ratio of b'% (for example, 60%) to brake the movement of the connectingpin 56 and thepushrod 61. Then when the measuring time t reaches the time point t3, the process goes fromstep 21 to step 25, in which theECU 70 sets the duty ratio Rd to zero to demagnetize theelectromagnetic solenoid 60. -
FIG. 9(2) shows changes of the voltage duty control of theelectromagnetic solenoid 60 in the above-described disconnection control. - At the time point t1 (corresponding to the time measurement starting point, t=0) at which the
internal combustion engine 10 shifts to the low-load condition from the state in which the firstintake rocker arm 51 and the secondintake rocker arm 52 are integrally connected by inserting the connectingpin 56 into therecess 51h in the high-load condition to cause the connectingpin 56 to extend across bothrecesses ECU 70 demagnetizes theelectromagnetic solenoid 60 with the duty ratio Rd set to zero, so that the connectingpin 56 and thepushrod 61 move quickly with the urging force of thespring 54. However, the setting is made such that, at the time point t2, theelectromagnetic solenoid 60 is energized with the brake duty ratio b'% to brake the movement of the connectingpin 56 and thepushrod 61, and, in the vicinity of the time point T3 at which the brake control ends, the connectingpin 56 comes out of therecess 51h. Thus, the movement speed just before the connectingpin 56 and thepushrod 61 stop can be easily reduced and the generation of a hitting sound can be prevented. - The time point t2 to start the energization with the brake duty ratio b'% and the brake duty ratio b'% are preset to proper values. However, by previously obtaining and mapping optimum values of the time point t2 and the brake duty ratio b'% corresponding to oil temperature, it is possible to perform brake control with the optimum time point t2 and the optimum brake duty ratio b'% which correspond to oil temperature. Thus, the movement speed just before the
pushrod 61 stops can be further reduced and the generation of a hitting sound can be prevented. - Further, as for the time point t2 to start the energization with the brake duty ratio b'% for braking, a position where the
pushrod 61 returns with the urging force of thespring 54 is detected by a position sensor, and a time point at which thepushrod 61 has returned to an optimum position for braking is detected. This time point may be set as the time point t2 to energize theelectromagnetic solenoid 60 with the brake duty ratio b'%. - By previously obtaining and mapping the correlation between the above-described brake duty ratio (b') and oil temperature, it is possible to properly brake the moving core member (61, 62) on the basis of the map, depending on the temperature state of the internal combustion engine 10 (more specifically, the change in resistance of the electromagnetic solenoid with temperature or the change in viscosity of lubricating oil with temperature), and reduce the generation of a hitting sound.
- Next, the connection control routine will be described with reference to an exemplary flowchart of
FIG. 8 and the voltage duty control shown inFIG. 10 . - When the
internal combustion engine 10 shifts from the low-load condition to the high-load condition, the process proceeds to the connection control routine. Just before that, the duty ratio Rd is 0% and the firstintake rocker arm 51 and the secondintake rocker arm 52 are in the disconnected state. - When the time measurement is started (step 7) and the process proceeds to the connection control routine (step 8), the
ECU 70 determines instep 31 ofFIG. 8 whether or not lubricating oil temperature (oil temperature) Yt detected by theoil temperature sensor 27 falls within a predetermined oil temperature range. - When the oil temperature is greater than about 60°C, the lubricating oil for smooth sliding of the connecting
pin 56 becomes less viscous. Also, when the oil temperature is smaller than about 80°C, the coil resistance of theelectromagnetic solenoid 60 is small and the coil current flows through easily. For this reason, without change in applied voltage, the projecting force of the moving core member (61, 62) increases. Thus, when the electromagnetic solenoid is energized in the oil temperature range of approximately 60°C to 80°C, the movement speed of the connecting pin (56) is likely to increase, and a hitting sound is more likely to be generated. Therefore, a predetermined oil temperature range in which the movement speed is likely to increase is preset between approximately 60°C and 80°C, and duty control of the electromagnetic solenoid (60) is varied according to within and outside the predetermined oil temperature range. - In this embodiment, the predetermined oil temperature range is set to 60°C<Yt<80°C.
- This predetermined oil temperature range is the temperature range in which vibration generated in the cylinder head becomes larger than that in other portions.
- In
step 31, theECU 70 determines whether or not the oil temperature Yt falls within a predetermined oil temperature range (60°C<Yt<80°C). If theECU 70 determines that the oil temperature Yt falls outside the predetermined oil temperature range (Yt≤60°C, 80°C≤Yt), the process goes to step 32. Instep 32, theECU 70 determines whether or not the measuring time t reaches predetermined time T that is sufficient to complete the connection. Initially, the measuring time t has not reached the predetermined time T, and therefore the process proceeds to step 33. Instep 33, theECU 70 determines whether subtraction counting value i is zero or not. If the subtraction counting value i is not zero, the process goes to step 34. Instep 34, theECU 70 sets the duty ratio Rd to a normal movement starting duty ratio of a% (for example, 90%) for starting the movement of the connectingpin 56 and starts duty control of theelectromagnetic solenoid 60 with the duty ratio a% greater than the connection maintaining duty ratio b%, and energizes theelectromagnetic solenoid 60 to cause thepushrod 61 to press the connectingpin 56 that is in position to release the connection. - Then in
step 35, theECU 70subtracts 1 from the subtraction counting value i. - The subtraction counting value i is initially set to initial value I (steps 39 and 41). When the subtraction counting value i becomes zero while
steps 31 to 35 are repeated and duty control is performed with the normal movement starting duty ratio a%, the process skips overstep 33 to step 36. Instep 36, theECU 70 determines whether another subtraction counting value j is zero or not. - If the subtraction counting value j is not zero, the process goes to step 37. In
step 37, theECU 70 sets the duty ratio Rd to the connection maintaining duty ratio b% to perform duty control, and innext step 38, subtracts 1 from the subtraction counting value j. - The subtraction counting value j is initially set to initial value J (steps 39 and 41). When the subtraction counting value j becomes zero while
steps step 36 to step 39. Instep 39, theECU 70 sets the subtraction counting values i and j to the initial value I and J, respectively. - At this point, if the measuring time t has not reached the predetermined time T, the process proceeds from
step 32 to step 33, in which the duty control with the normal movement starting duty ratio a% and the duty control with the connection maintaining duty ratio b% are executed, and repeated until the measuring time t has reached the predetermined time T. - And finally, when the measuring time t has reached the predetermined time T, the process skips over
step 32 to step 40. Instep 40, theECU 70 fixes the duty ratio Rd to the connection maintaining duty ratio b% for duty control, and innext step 41, reliably sets the subtraction counting values i and j to the initial value I and J, respectively. -
FIG. 10(1) shows changes of the voltage duty control of theelectromagnetic solenoid 60 in the above-described connection control. - At the time point t1 (corresponding to the time measurement starting point, t=0) at which the
internal combustion engine 10 shifts to the high-load condition from the state in which the connection is released by demagnetizing theelectromagnetic solenoid 60 with a duty ratio of 0% in the low-load condition and bringing the connectingpin 56 out of therecess 51h, theECU 70 performs voltage duty control of theelectromagnetic solenoid 60 with the duty ratio Rd set to the normal movement starting duty ratio a%, and starts the energization of theelectromagnetic solenoid 60. Thus, thepushrod 61 applies a large pressure to the connectingpin 56. At the time point t2 at which the subtraction counting value i becomes zero, theECU 70 decreases the duty ratio Rd to the connection maintaining duty ratio b%. Then at the time point t3 at which the subtraction counting value j becomes zero, theECU 70 increases again the duty ratio Rd to the normal movement starting duty ratio a%. The duty controls with the normal movement starting duty ratio a% and the connection maintaining duty ratio b% are repeated until the predetermined time T. Therefore, as shown by dashed lines inFIG. 10(1) , the actual voltage repeats to turn from the normal movement starting voltage to the connection maintaining voltage, and, at the predetermined time T, is fixed to the connection maintaining voltage. - In this manner, the increase in the movement speed is adjusted by repeatedly changing a great pressure of the normal movement starting duty ratio a% at the start of the movement of the connecting
pin 56 to a smaller pressure of the connection maintaining duty ratio b%, so that the connectingpin 56 can be stopped in a manner extending across bothrecesses spring 54 all the way in can be avoided. - Furthermore, the duty control with the normal movement starting duty ratio a% is performed, thereby inserting the connecting
pin 56 into therecess 51h and achieving connection. Also, the duty control with the connection maintaining duty ratio b% is performed, thereby maintaining the connection. Thus, the power consumption of theelectromagnetic solenoid 60 can be reduced. - On the other hand, in
step 31, if it is determined that the oil temperature Yt falls within the predetermined oil temperature range (60°C<Yt<80°C), the process goes to step 42. - Note that steps 42 to 51 correspond to the above-described
steps 32 to 41. The difference therebetween is in that, instep 44, the duty ratio Rd is set to a special movement starting duty ratio of a'% (for example, 80%) that is smaller than the normal movement starting duty ratio a% and greater than the connection maintaining duty ratio b%. As for the rest, the steps are the same. - When the oil temperature Yt falls within the predetermined oil temperature range (60°C<Yt<80°C), the movement speed of the connecting
pin 56 is likely to increase. Therefore, referring toFIG. 10(2) , theECU 70 energizes theelectromagnetic solenoid 60 with the special movement starting duty ratio a'% that is smaller than the normal movement starting duty ratio a% and greater than the connection maintaining duty ratio b%, and controls the movement of the connectingpin 56. Then theECU 70 drives theelectromagnetic solenoid 60 while repeatedly performing control for changing to the connection maintaining duty ratio b% that is smaller than the special movement starting duty ratio a'%. Thus, the movement speed is adjusted to a value suitable for an oil temperature in the predetermined oil temperature range (60°C<Yt<80°C) by repeatedly changing the pressure from a value smaller than normal of the special movement starting duty ratio a'% at the start of the movement of the connectingpin 56 to a smaller value of the connection maintaining duty ratio b%, so that the connectingpin 56 can be stopped in a manner extending across bothrecesses spring 54 all the way in can be avoided. - Furthermore, the duty control with the special movement starting duty ratio a'% is performed, thereby inserting the connecting
pin 56 into therecess 51h and connecting the firstintake rocker arm 51 and the secondintake rocker arm 52 together. Also, the duty control with the connection maintaining duty ratio b% is performed, thereby maintaining the connection. Thus, the power consumption of theelectromagnetic solenoid 60 can be reduced. - In both cases where the oil temperature Yt falls within and outside the predetermined oil temperature range, even if the connecting
pin 56 comes out of therecess 51h of one of the two recesses, duty control is repeatedly performed with the normal movement starting duty ratio a% or the special movement starting duty ratio a'% so that the connectingpin 56 is inserted into therecess 51h. Thus, the connected state can be ensured. - In this embodiment, the predetermined oil temperature range is set to 60°C<Yt<80°C, which is an optimum range. However, the lower limit is not limited to 60°C, but also can be set to an oil temperature of around 60°C. Also, the upper limit is not limited to 80°C, but also can be set to an oil temperature of around 80°C.
- It should be noted that the special movement starting duty ratio a'% is set, as the duty ratio Rd that permits the start of movement of the connecting
pin 56, to a predetermined constant value that is smaller than the normal movement starting duty ratio a% and greater than the connection maintaining duty ratio b%. However, the optimum special movement starting duty ratio a'% may be previously obtained and mapped corresponding to oil temperature (such a map that the higher the oil temperature, the smaller the special movement starting duty ratio a'%). Thus, the movement speed is adjusted to a value more suitable for oil temperature by determining the special movement starting duty ratio a'% in accordance with oil temperature, so that the connectingpin 56 can be stopped in a connecting position. - It also should be noted that the correlation of the normal movement starting duty ratio a and the special movement starting duty ratio a'% with oil temperature may be previously obtained and mapped. Thus, it is possible to more properly change the speed of the moving core member (61, 62) on the basis of the map, depending on the temperature state of the internal combustion engine (more specifically, the change in resistance of the electromagnetic solenoid with temperature or the change in viscosity of lubricating oil with temperature), and reduce the generation of a hitting sound.
-
- 1
- Motorcycle
- 2
- Head pipe
- 3
- Main frame
- 4
- Down frame
- 10
- Internal combustion engine
- 11
- Crankcase
- 12
- Cylinder block
- 13
- Cylinder head
- 14
- Cylinder head cover
- 15
- Intake valve
- 16
- Throttle body
- 17
- Air cleaner
- 18
- Exhaust pipe
- 19
- Muffler
- 20
- Fuel injection valve
- 21
- Piston
- 22
- Connecting rod
- 25
- Crankshaft
- 26
- Spark plug
- 27
- Oil temperature sensor
- 30
- Combustion chamber
- 31
- Intake port
- 32
- Exhaust port
- 33
- Intake valve
- 34
- Exhaust valve
- 35
- Intake valve spring
- 36
- Exhaust valve spring
- 37
- Coil spring
- 38
- Lifter
- 40
- Variable valve train
- 41
- Camshaft
- 42, 43
- Bearing
- 44
- Chain sprocket
- 47
- Intake rocker arm shaft
- 48
- Exhaust rocker arm shaft
- 51
- First intake rocker arm
- 52
- Second intake rocker arm
- 53
- Exhaust rocker arm
- 54
- Spring
- 55
- Plunger
- 56
- Connecting pin
- 60
- Electromagnetic solenoid
- 61
- Pushrod
- 62
- Pressure body
- 70
- ECU
Claims (9)
- A variable valve train for an internal combustion engine in which: rocker arms (51, 52) journaled coaxially with and adjacent to each other rock in contact with cam lobes (41i, 41ii) having different profiles of a camshaft, and an intake valve (33) is opened and closed by rocking of one rocker arm (51) of the rocker arms;
a connecting pin (56) urged by a spring (54) moves between respective hole portions (51h, 52h) formed in the rocker arms (51, 52), thereby enabling a connection between the rocker arms (51, 52);
the connecting pin (56) is moved by forward and backward movement of a moving core member (61, 62) of an electromagnetic solenoid (60); and
control means (70) energizes the electromagnetic solenoid (60) to cause the moving core member (61, 62) to protrude, and thereby the connecting pin (56) to move against urging force of the spring (54) so that the rocker arms (51, 52) are connected together and integrally rocked,
wherein the control means (70) duty controls the electromagnetic solenoid (60) and drives the moving core member (61, 62).
characterized in that,
in a disconnected state of the rocker arms (51, 52) in which the connecting pin (56) is fitted in the other hole portion (52h) of the hole portions to allow the rocker arms (51, 52) to rock independently, from a demagnetized state of the electromagnetic solenoid (60), the control means (70) duty controls the electromagnetic solenoid (60) with a normal movement starting duty ratio (a) that causes the connecting pin (56) to start to move against urging force of the spring (54), and then duty controls the electromagnetic solenoid (60) with a connection maintaining duty ratio (b) smaller than the normal movement starting duty ratio (a) to insert the connecting pin (56) into one hole portion (51h) of the hole portions so that the connecting pin (56) extends across both hole portions (51h, 52h), thereby connecting the rocker arms (51, 52) together. - The variable valve train for the internal combustion engine according to Claim 1, wherein a process of duty controlling the electromagnetic solenoid (60) with the normal movement starting duty ratio (a) and then duty controlling the electromagnetic solenoid (60) with the connection maintaining duty ratio (b) is repeated multiple times, until a measuring time t reaches a predetermined time T that is sufficient to complete the connection, whereby the connection maintaining duty control is fixed when the measuring time t has reached the predetermined time T.
- The variable valve train for the internal combustion engine according to Claim 2, further comprising:oil temperature detecting means (27) for detecting temperature of lubricating oil of the internal combustion engine (10),
wherein: the control means (70) presets a predetermined oil temperature range of approximately 60°C to 80°C;
when the oil temperature detected by the oil temperature detecting means (27) falls outside the predetermined oil temperature range, the control means (70) repeats multiple times the process of duty controlling the electromagnetic solenoid (60) with the normal movement starting duty ratio (a) that causes the connecting pin (56) to start to move against urging force of the spring (54), and then duty controlling the electromagnetic solenoid (60) with the connection maintaining duty ratio (b) smaller than the normal movement starting duty ratio (a), until the measuring t reaches the predetermined time T; and
when an oil temperature detected by the oil temperature detecting means (27) falls within the predetermined oil temperature range, the control means (70) repeats multiple times a process of controlling movement of the connecting pin (56) with a special movement starting duty ratio (a') smaller than the normal movement starting duty ratio (a) and greater than the connection maintaining duty ratio (b), and then duty controlling the electromagnetic solenoid (60) with the connection maintaining duty ratio (b), until the measuring time t reaches the predetermined time T. - The variable valve train for the internal combustion engine according to Claim 3, wherein the predetermined oil temperature range is a temperature range in which vibration generated in a cylinder head becomes larger than in other portions.
- The variable valve train for the internal combustion engine according to Claims 3 and 4, wherein the normal movement starting duty ratio (a) and the special movement starting duty ratio (a') are determined from a map correlated with an oil temperature value.
- The variable valve train for the internal combustion engine according to any one of Claims 1 to 5, wherein the control means (70) performs control to decrease the duty ratio in a stepwise fashion from the connection maintaining duty ratio (b) that maintains the connected state of the rocker arms (51, 52) by causing the connecting pin (56) to extend across both hole portions (51h, 52h), and adjusts movement speed of the moving core member (61, 62) to stop the moving core member (61, 62), thereby releasing the connection between the rocker arms (51, 52).
- The variable valve train for the internal combustion engine according to any one of Claims 1 to 5, wherein the control means (70) changes the duty ratio to zero from the connection maintaining duty ratio (b) that maintains the connected state of the rocker arms (51, 52) by causing the connecting pin (56) to extend across both hole portions (51h, 52h), and then controls the duty ratio to a brake duty ratio (b') at a predetermined timing so that the moving core member (61, 62) is reduced in movement speed and stopped, thereby releasing the connection between the rocker arms (51, 52).
- The variable valve train for the internal combustion engine according to Claim 7, wherein the brake duty ratio (b') is determined from the map correlated with the oil temperature value.
- The variable valve train for the internal combustion engine according to Claim 7, wherein a position of the moving core member (61, 62) is detected by a position sensor, and at a predetermined position, control is performed with the brake duty ratio (b') so that the moving core member (61, 62) is reduced in movement speed and stopped, thereby releasing the connection between the rocker arms (51, 52).
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2012082787A JP5984460B2 (en) | 2012-03-30 | 2012-03-30 | Variable valve mechanism for internal combustion engine |
Publications (2)
Publication Number | Publication Date |
---|---|
EP2644854A1 EP2644854A1 (en) | 2013-10-02 |
EP2644854B1 true EP2644854B1 (en) | 2015-06-03 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP13161086.7A Active EP2644854B1 (en) | 2012-03-30 | 2013-03-26 | Variable valve train for internal combustion engine |
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EP (1) | EP2644854B1 (en) |
JP (1) | JP5984460B2 (en) |
Families Citing this family (5)
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JP2015090098A (en) * | 2013-11-06 | 2015-05-11 | ヤマハ発動機株式会社 | Straddle type vehicle |
JP5883480B2 (en) * | 2013-12-05 | 2016-03-15 | ヤマハ発動機株式会社 | Internal combustion engine and saddle riding type vehicle |
US10006317B2 (en) * | 2015-09-29 | 2018-06-26 | Caterpillar Inc. | Valve actuation system |
JP2019510161A (en) * | 2016-03-11 | 2019-04-11 | イートン インテリジェント パワー リミテッドEaton Intelligent Power Limited | Electromagnetic coupling for rocker arm assembly |
EP4028649A1 (en) | 2019-09-10 | 2022-07-20 | Eaton Intelligent Power Limited | Valvetrain with rocker shaft housing magnetic latch |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19522582A1 (en) * | 1995-06-16 | 1996-12-19 | Siemens Ag | Circuit arrangement for operating an electromagnet |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6463897B2 (en) * | 2000-05-16 | 2002-10-15 | Delphi Technologies, Inc. | Mechanical assist actuation bracket for deactivation and two-step roller finger followers |
JP4476241B2 (en) * | 2005-06-20 | 2010-06-09 | 日立オートモティブシステムズ株式会社 | Valve operating device for internal combustion engine |
JP2009115036A (en) * | 2007-11-08 | 2009-05-28 | Toyota Motor Corp | Control device for variable valve gear |
JP2009293613A (en) * | 2008-05-08 | 2009-12-17 | Toyota Motor Corp | Valve system of internal-combustion engine |
JP2010101270A (en) * | 2008-10-24 | 2010-05-06 | Toyota Motor Corp | Valve gear of internal combustion engine |
JP5071584B2 (en) * | 2009-02-25 | 2012-11-14 | トヨタ自動車株式会社 | Variable valve operating device for internal combustion engine |
JP5455838B2 (en) * | 2010-08-11 | 2014-03-26 | 本田技研工業株式会社 | Variable valve mechanism |
-
2012
- 2012-03-30 JP JP2012082787A patent/JP5984460B2/en not_active Expired - Fee Related
-
2013
- 2013-03-26 EP EP13161086.7A patent/EP2644854B1/en active Active
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19522582A1 (en) * | 1995-06-16 | 1996-12-19 | Siemens Ag | Circuit arrangement for operating an electromagnet |
Also Published As
Publication number | Publication date |
---|---|
JP2013213408A (en) | 2013-10-17 |
EP2644854A1 (en) | 2013-10-02 |
JP5984460B2 (en) | 2016-09-06 |
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