US20090107431A1 - Variable Valve System For Internal Combustion Engine - Google Patents
Variable Valve System For Internal Combustion Engine Download PDFInfo
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- US20090107431A1 US20090107431A1 US11/988,181 US98818106A US2009107431A1 US 20090107431 A1 US20090107431 A1 US 20090107431A1 US 98818106 A US98818106 A US 98818106A US 2009107431 A1 US2009107431 A1 US 2009107431A1
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- valve
- cam
- rotation speed
- electric motor
- open period
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- 238000002485 combustion reaction Methods 0.000 title claims abstract description 36
- 210000001331 nose Anatomy 0.000 description 25
- 230000008859 change Effects 0.000 description 5
- 230000010355 oscillation Effects 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 2
- 241001274197 Scatophagus argus Species 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
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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
- F01L1/02—Valve drive
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
- F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
- F01L1/34413—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear using composite camshafts, e.g. with cams being able to move relative to the camshaft
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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
- F01L9/00—Valve-gear or valve arrangements actuated non-mechanically
- F01L9/20—Valve-gear or valve arrangements actuated non-mechanically by electric means
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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
- F01L9/00—Valve-gear or valve arrangements actuated non-mechanically
- F01L9/20—Valve-gear or valve arrangements actuated non-mechanically by electric means
- F01L9/22—Valve-gear or valve arrangements actuated non-mechanically by electric means actuated by rotary motors
Definitions
- the invention relates generally to a variable valve system for an internal combustion engine, which opens and closes, using a cam, an intake valve and an exhaust valve of an internal combustion engine. More specifically, the invention relates to a variable valve system for an internal combustion engine, which uses an electric motor to obtain power to drive a cam.
- JP-A-2004-183612 describes an internal combustion engine provided with a variable valve system that can change valve opening/closing characterstics (a valve lift amount, valve opening time, valve closing time, etc.) of an intake valve and an exhaust valve.
- the variable valve system drives a cam using power from au electric motor instead of power transmitted from a crankshaft. Accordingly, the variable valve system can flexibly control the rotation speed and the rotation direction of the cam independently of the rotation of the crankshaft.
- the phase of the cam can be changed by increasing/decreasing the rotation speed of the cam while the intake valve or the exhaust valve is closed (phase variable control).
- the valve-open duration can be changed by increasing/decreasing the rotation speed of the cam while the intake valve or the exhaust valve is open (valve-open duration variable control). If the rotation of the cam is reversed before the valve is maximally lifted while the valve is open, the actual valve lift amount is less than the maximum valve lift amount (valve lift amount variable control).
- the valve opening/closing characteristics of the intake valve and the exhaust valve can be changed with greater flexibility.
- An electric motor that is used to drive the cams may be shared by all the cylinders.
- each cylinder may be provided with an electric motor.
- the cylinders may be divided into multiple groups, and an electric motor may be provided to each group.
- an electric motor may drive the cams corresponding to two cylinders that are different in the rotation phase of the cams. In this case, if the cams are oscillated by alternately switching the rotation direction of the electric motor between the normal rotation direction and reverse rotation direction, the valve lift amount variable control described above can be performed simultaneously on the valves of the two cylinders.
- each cam corresponding to one of the cylinders opens and closes the valve using, from among two ramp portions thereof, only the ramp portion used to open the valve during normal rotation of the arm, and each cam corresponding to the other cylinder opens and closes the valve using only the ramp portion used to close the valve during normal rotation of the cam.
- a cam commonly employed in a valve system for an internal combustion engine is formed such that the shape of the ramp portion on the valve opening side with respect to the cam nose is different from that on the valve closing side with respect to the cam nose.
- the ramp portion on the valve opening side is steeply inclined in order to quickly open the valve to reduce the valve-pen duration, thereby increasing the time area (the value obtained by integrating the valve opening amount) per unit valve-open duration.
- the ramp portion on the valve closing side is moderately inclined in order to gradually close the valve to reduce the speed at which the valve contacts a valve seat, thereby reducing vibration and noise that are caused when the valve contacts the valve seat.
- valve lift amount variable control is performed simultaneously on the valves of the two cylinders, each valve of one of the cylinders is quickly opened and closed by the steeply inclined ramp portion, and each valve of the other cylinder is gradually opened and closed by the moderately inclined ramp portion. This causes a difference in the valve lift curve between the valves of the two cylinders. As a result, the intake air amount varies between the two cylinders, causing torque fluctuation in the internal combustion engine as a whole.
- variable valve system can change the valve opening/closing characteristics with great flexibility.
- flexibility in the valve opening/closing characteristics is provided under a certain degree of constraint, because alternately switching the rotation direction of the cams causes the difference in the valve lift curve between the valves of the two cylinders.
- An object of the invention is to provide a variable valve system for an internal combustion engine, which can change valve opening/closing characteristics with greater flexibility.
- a first aspect of the invention relates to a variable valve system for an internal combustion engine.
- the variable valve system includes an electric motor that can be rotated in any one of the normal rotation direction and the reverse rotation direction; a first cam that is driven by the electric motor, a second cam that has the same shape as the first cam, that is driven by the electric motor, and that differs from the first cam in the rotation phase; a first valve that is opened and closed by the first cam; a second valve that is opened and closed by the second cam; and a control unit that controls rotation of the electric motor.
- each of the first cam and the second cam is symmetric with respect to the straight line passing the cam center and the cam nose.
- each of the first cam and the second cam is symmetric with respect to the straight line passing the cam center and the cam nose, the same valve lift curve can be obtained regardless of whether the cam is rotated in the normal rotation direction or the reverse rotation direction.
- the rotation direction and the rotation speed of each cam can be flexibly controlled by the control unit, because the electric motor is used to obtain power to drive the cams.
- the valve opening/closing characteristics of the first valve and the second valve can be changed with greater flexibility.
- control unit may alternately switch the rotation direction of the electric motor between the normal rotation direction and the reverse rotation direction such that the first valve is opened and closed using, from among two ramp portions of the first cam, the ramp portion used to open the first valve when the electric motor is rotated in a given direction (hereinafter, referred to as the “opening ramp portion”), and the second valve is opened and closed using, from among two ramp portions of the second cam, the ramp portion used to close the second valve when the electric motor is rotated in the given direction (hereinafter, referred to as the “closing ramp portion”).
- the first valve is opened and closed using the opening ramp portion of the first cam
- the second valve is opened and closed using the closing ramp portion of the second cam. Opening/closing each of the valves using only one of the ramp portions of the corresponding cam enables the valve to be driven by a lift amount that is less than that when the cam is rotated in only one direction and the valve is opened and closed using the entirety of the cam.
- the first cam and the second cam have the same shape, and each of the first cam and the second cam is symmetric with respect to the straight line passing the cam center and the cam nose.
- opening/closing one of the valves using the opening ramp portion and the other valve using the closing ramp portion does not cause a difference between the two valve lift curves.
- control unit may control the rotation speed of the electric motor such that the rotation speed at the start time of the open period of the first valve is higher than the rotation speed at the end time of the open period of the first valve, and the rotation speed at the start time of an open period of the second valve is higher than the rotation speed at the end time of the open period of the second valve.
- the rotation speed of the electric motor at the start time of the open period of each valve is made higher than that at the end time of the open period.
- the valve-pen duration of each valve can be reduced to increase the time area (the value obtained by integrating the valve opening amount) per unit valve-open duration. Accordingly, even if the ramp portions of each cam are moderately inclined to have the valve gradually contact a valve scat, the valve lift curve, according to which the valve is opened quickly and closed gradually, can be obtained.
- control unit may control the rotation speed of the electric motor such that the rotation speed at the end time of the open period of the first valve is lower than the rotation speed at the start time of the open period of the first valve, and the rotation speed at the end time of the open period of the second valve is lower than the rotation speed at the start time of the open period of the second valve.
- the first valve is opened and closed using the opening ramp portion of the first cam
- the second valve is opened and closed using the closing ramp portion of the second cam. Opening/closing each of the valves using only one of the ramp portions of the corresponding cam enables the valve to be driven by a lift amount that is less than that when the cam is rotated in only one direction and the valve is opened and dosed using the entirety of the cam.
- the first cam and the second cam have the same shape, and each of the first cam and the second cam is symmetric with respect to the straight line passing the cam center and the cam nose.
- opening/closing one of the valves using the opening ramp portion and the other valve using the closing ramp portion does not cause a difference between the two valve lift curves.
- variable valve system may further include a camshaft used to take air into cylinders or discharge exhaust gas from the cylinders.
- the camshaft is driven by the electric motor controlled by the control unit.
- the electric motor drives the first cam provided onto the camshaft.
- the electric motor drives the second cam provided onto the camshaft.
- the camshaft is directly driven by the electric motor, and the camshaft drives the first cam and the second cam. Accordingly, the variable valve system has excellent response characteristics.
- the variable valve system can appropriately perform the opening/closing control for an intake valve and an exhaust valve, thereby considerably improving the operating performance of the internal combustion engine.
- a second aspect of the invention relates to a variable valve system for an internal combustion engine.
- the variable valve system includes an electric motor that can be rotated in any one of a normal rotation direction and a reverse rotation direction; multiple cams that are provided to take air into cylinders or discharge exhaust gas from the cylinders, and that are driven by the electric motor, multiple valves that are opened and closed by the respective cams; and a control unit that controls rotation of the electric motor.
- Each of the cams is symmetric with respect to the straight line passing the cam center and the cam nose.
- each valve is opened and closed by the corresponding cam that is symmetric with respect to the straight line passing the cam center and the cam nose, the same valve lift curve can be obtained regardless of whether the cam is rotated in the normal rotation direction or the reverse rotation direction.
- the rotation direction and the rotation speed of each cam can be flexibly controlled by the control unit, because the electric motor is used to obtain power to drive the cams.
- the valve opening/closing characteristics of valves can be changed with greater flexibility.
- control unit may alternately switch the rotation direction of the electric motor between the normal rotation direction and the reverse rotation direction such that the cam opens and closes the valve using only one of two ramp portions of the cam. Because the valve can be opened and closed using only one of the two ramp portions, the valve can be driven by a lift amount that is less than that when the valve is opened and closed by rotating the cam in only one direction and using the entirety of the cam.
- control unit may control the rotation speed of the electric motor such that the rotation speed at the start time of the open period of the valve is higher than the rotation speed at the end time of the open period of the valve.
- the rotation speed of the electric motor at the start time of the open period of each valve is made higher than that at the end time of the open period.
- the valve-open duration of each valve can be reduced to increase the time area per unit valve-open duration. Accordingly, even if the ramp portions of each cam are moderately inclined to have the valve gradually contact a valve seat, the valve lift curve, according to which the valve is opened quickly and closed gradually, can be obtained.
- control unit may control the rotation speed of the electric motor such that the rotation speed at the end time of the open period of the valve is lower than the rotation speed at the start time of the open period of the valve.
- the rotation speed of the electric motor at the end time of the open period of each valve is made lower than that at the start time of the open period.
- vibration and noise that are caused when the valve contacts the valve seat can be reduced by reducing the speed at which the valve contacts the valve seat. Accordingly, even if the ramp portions of each cam are steeply inclined to increase the time area per unit valve-open duration, the valve lift curve, according to which the valve is opened quickly and closed gradually, can be obtained.
- control unit may receive data from a sensor that detects an engine operating state.
- the internal combustion engine may be an in-line four-cylinder engine.
- the power stroke may take place in the internal combustion engine in the order of a first cylinder, a third cylinder, a fourth cylinder, and a second cylinder.
- first cam and the first valve may constitute a valve unit for the fourth cylinder
- second cam and the second valve may constitute a valve unit for the first cylinder
- first cam and the second cam may be arranged such that the phase of the cam nose of the fast cam and the phase of the cam nose of the second cam deviate from each other by 180 degrees in the circumferential direction of the camshaft.
- FIG. 1 illustrates the perspective view of a variable valve system according to each of a first embodiment and a second embodiment of the invention
- FIG. 2 illustrates the cross-sectional view of a camshaft taken along the plane perpendicular to the axis of the camshaft, which is used to describe the relative positional relationship between a cam corresponding to a cylinder # 1 and a cam corresponding to a cylinder # 4 ;
- FIG. 3 illustrates the graph showing the cam lift curve of the cam in FIG. 1 ;
- FIG. 4 illustrates the table showing cam lift curves that are used to describe examples of changes in the valve opening/closing characteristics obtained by the variable valve system in FIG. 1 ;
- FIGS. 5A to 5C illustrate the views showing oscillation of the cam when the valve is opened and closed by a small lift amount
- FIG. 6 illustrates the graph showing the valve lift curve obtained by performing the motor speed control according to the second embodiment of the invention.
- FIG. 7 illustrates the graph showing the valve lift curve obtained by performing the motor speed control according to a third embodiment of the invention.
- FIGS. 1 to 5 a first embodiment of the invention will be described with reference to FIGS. 1 to 5 .
- FIG. 1 illustrates the perspective view showing the structure of a variable valve system 10 according to the first embodiment.
- the variable valve system 10 drives an intake valve and an exhaust valve of an internal combustion engine 1 .
- an in-line four-cylinder engine is employed as the internal combustion engine 1 .
- reference numerals # 1 to # 4 denote first to cylinders of the internal combustion engine, respectively.
- the first to cylinders # 1 to # 4 are arranged in series.
- the power stroke order of the internal combustion engine 1 is # 1 ⁇ # 3 ⁇ # 4 ⁇ # 2 , as in the case of a commonly used internal combustion engine.
- the variable valve system 10 serves as a system that drives the intake valves of the cylinders.
- the structure on the exhaust valve side is not shown.
- the variable valve system 10 may be configured as a system that drives the exhaust valves of the cylinders instead of or in addition to the intake valves of the cylinders.
- each cylinder is provided with two intake valves 12 .
- Valve shafts 14 are fixed to the respective valves 12 .
- Valve lifters 16 are fitted to the respective valve shafts 14 at the upper portions thereof.
- a force of a valve spring (not shown) is applied to the valve shaft 14 . The spring force is applied such that the valve 12 is closed.
- Cams 50 , cams 52 , cams 54 , and cams 56 are arranged so as to contact the upper portions of the corresponding valve lifters 16 .
- the cams 50 denote the cams contacting the valve lifters 16 provided to the cylinder # 1 .
- the cams 52 denote the cams contacting the valve lifters 16 provided to the cylinder # 2 .
- the cams 54 denote the cams contacting the valve lifters 16 provided to the cylinder # 3 .
- the cams 56 denote the cams contacting the valve lifters 16 provided to the cylinder # 4 .
- cams 50 contacting the valve lifters 16 provided to the cylinder # 1 and the cams 56 contacting the valve lifters 16 provided to the cylinder # 4 are fixed to a camshaft 22 .
- the cams 52 contacting the valve lifters 16 provided to the cylinder # 2 and the cams 54 contacting the valve lifters 16 provided to the cylinder # 3 are fixed to a camshaft 24 that is rotatable with respect to the camshaft 22 and that is arranged coaxially with the camshaft 22 .
- each camshaft is shared by the cylinders where the power stroke takes place at different time. The power stroke takes place in one of these cylinders when the crankshaft has rotated by 360 degrees since the power stroke takes place in the other cylinder.
- camshafts namely, the camshaft 22 shared by the cylinder # 1 and the cylinder # 4 and the camshaft 24 shared by the cylinder # 2 and the cylinder # 3 are configured so as to be able to rotate and oscillate in the circumferential direction independently of each other.
- the camshaft 22 and the camshaft 24 are rotatably supported by a support member, for example, a cylinder head (not shown).
- a first driven gear 26 is coaxially fixed to the camshaft 22 .
- a first output gear 28 is meshed with the first driven gear 26 .
- the first output gear 28 is coaxially fixed to the output shaft of a first motor 30 .
- torque of the first motor 30 can be transmitted to the camshaft 22 via the first output gear 28 and the first driven gear 26 .
- a second driven gear 32 is coaxially fixed to the camshaft 24 .
- a second output gear 36 is meshed with the second driven gear 32 via an intermediate gear 34 .
- the second output gear 36 is coaxially fixed to the output shaft of a second motor 38 . With this structure, torque of the second motor 38 can be transmitted to the camshaft 24 via the second output gear 36 , the intermediate gear 34 , and the second driven gear 32 .
- FIG. 2 illustrates the cross-sectional view of the camshaft 22 taken along the plane perpendicular to the axis of the camshaft 22 .
- FIG. 2 shows the details of the camshaft 22 in FIG. 1 .
- the cams 50 corresponding to the cylinder # 1 and the cams 56 corresponding to the cylinder # 4 are fixed to the camshaft 22 .
- the cams 50 , 56 are arranged such that a cam nose 50 a of the cam 50 and a cam nose 56 a of the cam 56 deviate from each other by 180 degrees in the circumferential direction.
- each of the ramp portions 50 b , 50 c extends between the base circle portion and the apex of the cam nose 50 a .
- the ramp portion that initially contacts the valve lifter 16 during normal rotation of the camshaft 22 namely, the ramp portion used to open the valve 12 (# 1 ) is referred to as the opening ramp portion 50 b .
- the ramp portion that contacts the valve lifter 16 after the apex of the cam nose 50 a contacts the valve lifter 16 namely, the ramp portion used to close the valve 12 is referred to as the closing ramp portion 50 c .
- the ramp portion used to open the valve 12 (# 4 ) corresponding to the cam 56 (# 4 ) is referred to as an opening ramp portion 56 b
- the ramp portion used to close the valve 12 is referred to as a closing ramp portion 56 c.
- FIG. 3 illustrates the cam lift curve of the cam 50 corresponding to the cylinder # 1 .
- the lateral axis indicates the position of the cam in the circumferential direction
- the longitudinal line indicates the cam height (the height of the cam with respect to the cam base circle).
- the cam lift curve is indicated using the straight line connecting the cam center to the apex of the cam nose 50 a as the Y-axis.
- the cam lift curve of the opening ramp portion 50 b is shown on the left side with respect to the Y-axis
- the cam lift curve of the closing ramp portion 50 c is shown on the right side with respect to the Y-axis.
- the cam 50 is symmetric with respect to the straight line passing the cam center and the apex of the cam nose 50 a Accordingly, as shown in FIG. 3 , the cam lift curve of the opening ramp portion 50 b and the cam lift curve of the closing ramp portion 50 c are symmetric with respect to the Y-axis.
- the cam lift curve of the cam 56 corresponding to the cylinder # 4 is similar to the cam lift curve of the cam 50 corresponding to the cylinder # 1 shown in FIG. 3 .
- the cam 52 corresponding to the cylinder # 2 and the cam 54 corresponding to the cylinder # 3 are fixed to the camshaft 24 such that the phases of the cams 52 , 54 are deviated from each other by 180 degrees.
- Each of the cams 52 , 54 has the same shape as that of the cam 50 corresponding to the cylinder # 1 and the cam 56 corresponding to the cylinder # 4 .
- Each of the cams 52 , 54 is symmetric with respect to the straight line passing the cam center and the apex of the cam nose.
- the operation of the variable valve system 10 is controlled by an ECU 40 (Electronic Control Unit) 40 .
- the ECU 40 is connected to various sensors (not shown) that detect the operating state of the internal combustion engine, such as a crank angle sensor, a cam angle sensor, and an accelerator angle sensor.
- the ECU 40 is connected to various actuators such as an actuator for the first motor 30 , and an actuator for the second motor 38 , etc.
- the ECU 40 stores programs used to control the rotations of the first motor 30 and the second motor 38 .
- the ECU 40 processes the data transmitted from the various sensors, and control the rotations of the motors 30 , 38 based on the processing result.
- variable valve system 10 Next, the operation of the variable valve system 10 will be described with reference to FIG. 4 .
- camshaft 22 is driven by the first motor 30 will be described.
- the variable valve system 10 can variously change the valve opening/closing characteristics of the valve 12 as shown in FIG. 4 , by changing the phase of the camshaft 22 with the crankshaft using the first motor 30 .
- the “valve opening/closing characteristics” of the valve 12 is a generic term used to refer to the valve lift amount (maximum valve lift amount), the opening time of the valve 12 , and the closing time of the valve 12 .
- the “opening/closing characteristics” includes the valve-open duration that is defined by determining the opening time and the closing time, and the phase that is defined by determining the opening time (or closing time) while the valve-open duration is maintained constant.
- FIG. 4 illustrates the table showing the valve opening/closing characteristics of the valve 12 , which are variously obtained by the variable valve system 10 . More specifically, the wave-forms indicated by the solid lines in FIG. 4 show the valve lift curves obtained when the camshaft 22 is continuously rotated in the normal rotation direction at the basic speed (the rotation speed of the camshaft is half of that of the crankshaft). The wave-forms indicated by the double-dashed lines in FIG. 4 show the valve lift curves obtained after the operation of the camshaft 22 is changed. The lateral axis in each graph in FIG. 4 showing the valve lift curve indicates the crank angle (CA).
- CA crank angle
- the operation for changing the “phase”, shown in FIG. 4 will be described. If the rotation speed of the camshaft 22 is made higher than the basic speed while the valve 12 is closed, the phase of the camshaft 22 with respect of the crankshaft is changed relatively to the advance angle side. Therefore, the phase can be changed as shown in FIG. 4 . After the phase is changed, the desired phase can be maintained by returning rotation speed of the camshaft 22 to the basic speed. On the other band, if the rotation speed of the camshaft 22 is made lower than the basic speed while the valve 12 is closed, the phase of the camshaft 22 with respect to the crankshaft can be changed to the delay angle side.
- valve-open duration can be changed, as shown in FIG. 4 , by making the rotation speed of the camshaft 22 higher than the basic speed while the valve 12 is open.
- the ratio between the rotation period of the camshaft 22 and the rotation period of the crankshaft is maintained at 2:1 by making the rotation speed of the camshaft 22 lower than the basic speed, while the valve is closed, by the amount corresponding to the difference between the rotation speed of the camshaft 22 and the basic speed while the valve 12 is open.
- the valve-open duration can be made longer than that shown by the basic wave-form indicated by the solid line, by making the rotation speed of the camshaft 22 lower than the basic speed while the valve 12 is open. In this case, while the valve 12 is closed, the rotation speed of the camshaft 22 is controlled to be higher than the basic speed by the amount corresponding to the difference between the rotation speed of the camshaft 22 and the basic speed while the valve 12 is open.
- FIG. 4 illustrates the example in which the valve lift amount of the valve 12 is controlled to be less than the maximum valve amount.
- the change can be obtained by controlling the operation of the camshaft 22 as shown in FIGS. 5A to 5C .
- FIGS. 5A to 5C illustrate the operations of the cams 50 , 56 for changing “the valve-open duration and the valve lift amount”.
- the rotation direction of the camshaft 22 is alternately switched between the normal rotation direction and the reverse rotation direction, whereby the cams 50 , 56 are periodically oscillated.
- the camshaft 22 is rotated in the clockwise direction, that is, the normal rotation direction, as shown in FIG. 5A .
- the cam 56 corresponding to the cylinder # 4 presses down the valve lifter 16 (# 4 ) using the opening ramp portion 56 b .
- the first motor 30 is stopped before the apex of the cam nose 56 a of the cam 56 contacts the valve lifter 16 .
- the rotation direction of the fast motor 30 is switched such that the camshaft 22 is rotated in the counterclockwise direction, that is, the reverse rotation direction.
- the camshaft 22 is rotated in the reverse rotation direction, and the condition shown in FIG. 5B is achieved.
- the cam 56 oscillates while only the opening ramp portion 56 b , from among the two ramp portions 56 b , 56 c , contacts the valve lifter 16 (# 4 ). Accordingly, the valve 12 of the cylinder # 4 is operated according to the valve lift curve defined by the cam lift curve of the opening ramp portion 56 b of the cam 56 .
- the camshaft 22 is further rotated in the reverse rotation direction.
- the cam 50 corresponding to the cylinder # 1 presses down the valve lifter 16 (# 1 ) using the closing ramp portion 50 c .
- the first motor 30 is stopped before the cam nose 50 a contacts the valve lifter 16 (# 1 ).
- the rotation direction of the first motor 30 is switched again, and the camshaft 22 is rotated in the normal rotation direction until the condition shown in FIG. 5B is achieved.
- the cam 50 oscillates while only the closing ramp portion 50 c , from among the two ramp portions 50 b , 50 c , contacts the valve lifter 16 (# 1 ), and the valve 12 of the cylinder # 1 is operated according to the valve lift curve defined by the cam lift curve of the closing ramp portion 50 c of the cam 50 .
- the cams 50 , 56 are periodically oscillated by continuously performing the series of the operations described above. Accordingly, the valve lift amounts of the valves 12 of the cylinder # 1 and the cylinder # 4 can be simultaneously changed by the cams 50 , 56 both fixed to the camshaft 22 . At this time, the valve lift amounts of the valves 12 can be appropriately changed by appropriately changing the amounts of oscillation of the cams 50 , 56 . Also, when the cams 50 , 56 are oscillated, only the “valve lift amount” can be changed, without changing the valve-open duration, as shown in FIG. 4 , by appropriately changing the rotation speed of the first motor 30 .
- the oscillation period of the cams 50 , 56 is set to be twice as long as the rotation period of the crankshaft.
- valve 12 of the cylinder # 4 is opened and closed using the opening ramp portion 56 b of the cam 56 and the valve 12 of the cylinder # 1 is opened and closed using the closing ramp portion 50 c of the cam 50 by alternately switching the rotation direction of the first motor 30 to periodically oscillate the cams 50 , 56 .
- valve 12 of the cylinder # 1 and the valve 12 of the cylinder # 4 are opened and closed using only the closing ramp portion 50 c of the cam 50 and the opening ramp portion 56 b of the cam 56 , respectively. Accordingly, each of the valves 12 can be operated by a lift amount less than that when the valves 12 are opened and closed using the entireties of the cams 50 , 56 by rotating the camshaft 22 only in the normal rotation direction.
- the cams 50 , 56 which are simultaneously oscillated, have the same shape, and each of the cams 50 , 56 is symmetric with respect to the straight line passing the cam center and the apexes of the cam noses 50 a , 56 a . Accordingly, even if the valves 12 are operated using the closing ramp portion 50 c of the cam 50 and the opening ramp portion 56 b of the cam 56 , the valve lift curves of the valves 12 do not differ from each other. Accordingly, even if the valve lift amount of the valves 12 is changed, the intake air amount does not differ between the cylinder # 1 and the cylinder # 4 .
- variable valve system 10 With the variable valve system 10 according to the first embodiment described above, the operation of the cams 50 , 56 can be variously changed, because the rotation speed of the camshaft 22 is appropriately controlled by controlling the first motor 30 using the ECU 40 . Also, each of the cams 50 , 56 is symmetric with respect to the straight line passing the cam center and the apex of the cam nose. Accordingly, the same valve lift curve can be obtained regardless of whether the cams 50 , 56 are oscillated in the normal rotation direction or the reverse rotation direction. Therefore, with the variable valve system 10 according to the first embodiment, the rotation direction of the camshaft 22 is not limited to a certain direction, and the operation of the cams 50 , 56 can be variously changed by appropriately controlling the rotation direction of the camshaft 22 . Thus, the valve opening/closing characteristics of the valve 12 can be changed with great flexibility.
- the opening ramp portion 56 b is used in the cam 56 corresponding to the cylinder # 4
- the closing ramp portion 50 c is used in the cam 50 corresponding to the cylinder # 1
- the closing ramp portion 56 c may be used in the cam 56 corresponding to the cylinder # 4
- the opening ramp portion 50 b may be used in the cam 50 corresponding to the cylinder # 1 .
- Which ramp portion, from among the opening ramp portion and the closing ramp portion, should be used may be determined depending on the rotation position of each of the cams 50 , 56 when a command for staring the operation for changing the valve lift amount is issued.
- the cams 52 , 54 have the same shape, and each of the cams 52 , 54 is symmetric with respect to the straight line passing the cam center and the apex of the cam nose. Accordingly, the same valve lift curve can be obtained regardless of whether the camshaft 24 is rotated in the normal rotation direction or reverse rotation direction.
- the operation of the cams 52 , 54 can be variously changed by appropriately controlling, using the second motor 38 , the rotation speed and the rotation direction of the camshaft 24 and the angle by which the cams 52 , 54 are oscillated.
- the valve opening/closing characteristics of the valve 12 can be changed with great flexibility.
- FIG. 1 The structure of a variable valve system according to the second embodiment is shown in FIG. 1 , as in the first embodiment.
- the second embodiment is different from the first embodiment in the control of the rotation speed of the motors 30 , 38 .
- FIG. 6 illustrates the graph showing the valve lift curve that is obtained by controlling the rotation speed of the motors 30 , 38 using the ECU 40 .
- each of the cams 50 , 52 , 54 and 56 is symmetric with respect to the straight line passing the cam center and the apex of the cam nose. Accordingly, when the motors 30 , 38 are rotated at a constant speed, the rotation speed at the start time of the open period of the valve 12 is equal to the rotation speed at the end time of the open period of the valve 12 .
- the valve 12 is required to be quickly opened to quickly reduce the valve-open duration, thereby increasing the time area (the value obtained by integrating the valve opening amount) per unit valve-open duration. Meanwhile, the valve 12 is required to be gradually closed to reduce the speed at which the valve 12 contacts the valve seat, thereby reducing vibration and noise that are caused when the valve 12 contacts the valve seat.
- these two requirements contradict each other. Accordingly, if the shape of the cam is defined such that one of these requirements is fulfilled, the other requirement cannot be fulfilled.
- the second embodiment is made to fulfill both the requirement concerning the speed at which the valve 12 is opened and the requirement concerning the speed at which the valve 12 is closed.
- the valve 12 is quickly opened by appropriately selecting the shape of the cam, and the valve 12 is gradually closed by controlling the rotation speed of the motors 30 , 38 . More specifically, both of the opening ramp portion and the closing ramp portion of each of the cams 50 , 52 , 54 and 56 are steeply inclined so as to increase the time area per unit valve-open duration.
- the rotation speed NCclose of the motors 30 , 36 at the end time of the open period of the valve 12 is made lower than the rotation speed NCopen at the start time of the open period of the valve 12 .
- valve lift curve indicated by the slid line in FIG. 6 , according to which the valve 12 opens quickly and closes gradually, can be obtained.
- the time area per unit valve-open duration can be increased by reducing the valve-open duration of the valve 12
- vibration and noise that are caused when the valve 12 contacts the valve seat can be reduced by reducing the speed at which the valve 12 contacts the valve seat.
- the valve lift curve at the end time of the open period of the valve 12 is as indicated by the dashed line in FIG. 6 .
- control descried above can be applied not only to the case where each of the cams 50 , 52 , 54 and 56 is rotated in the normal rotation direction but also to the case where the cams 50 , 52 , 54 and 56 are oscillated by alternately switching the rotation direction of the motors 30 , 38 .
- variable valve system according to the third embodiment is characterized in that both the requirement concerning the speed at which the valve 12 is opened and the requirement concerning the speed at which the valve 12 is closed are fulfilled by appropriately selecting the shape of the cam and controlling the rotation speed of the motors 30 , 38 .
- FIG. 7 illustrates the graph showing the valve lift curve obtained by controlling the rotation speed of the motors 30 , 38 using the ECU 40 .
- the valve 12 is closed gradually by appropriately selecting the shape of the cam, and the valve 12 is opened quickly by controlling the rotation speed of the motors 30 , 38 . More specifically, the shape of both the opening ramp portion and the closing ramp portion of each of the cams 50 , 52 , 54 and 56 are moderately inclined to have the valve 12 gradually contact the valve seat.
- the rotation speed NCopen of the motors 30 , 38 at the start time of the open period of the valve 12 is made higher than the rotation speed NCclose at the end time of the open period of the valve 12 .
- valve lift curve indicated by the solid line in FIG. 7 , according to which the valve 12 quickly opens and gradually closes, can be obtained as in the second embodiment.
- the area per unit valve-open duration can be increased by reducing the valve-pen duration of the valve 12
- vibration and noise which are caused when the valve 12 contacts the valve seat can be reduced by reducing the speed at which the valve 12 contacts the valve seat.
- the valve lift curve at the start time of the open period of the valve 12 is as indicated by the dashed line shown in FIG. 7 .
- control described above can be applied not only to the case where each of the cams 50 , 52 , 54 and 56 is rotated in the normal rotation direction but also to the case where the cams 50 , 52 , 54 and 56 are oscillated by alternately switching the rotation direction of the motors 30 , 38 .
- the cams corresponding to two cylinders are driven by one motor.
- the cams corresponding to one cylinder may be driven by one motor.
- the shape of each cam is symmetric with respect to the straight line passing the cam center and the apex of the cam nose.
- the same valve lift curve can be obtained regardless of whether the cam is rotated in the normal rotation direction or the reverse rotation direction. Accordingly, the rotation direction and the rotation speed of the cam can be flexibly set, whereby the valve opening/closing characteristics of the valves can be changed with great flexibility.
- the power stroke order of the internal combustion engine 1 is # 1 ⁇ # 3 ⁇ # 4 ⁇ # 2 .
- the invention can be applied to an internal combustion engine where the power stroke order is # 1 ⁇ # 2 ⁇ # 4 ⁇ # 3 .
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Abstract
The invention relates to a variable valve system for an internal combustion engine including an electric motor that can be rotated in any one of a normal rotation direction and a reverse rotation direction; a first cam that is driven by the electric motor; a second cam that has a same shape as the first cam, that is driven by the electric motor, and that differs from the first cam in a rotation phase; a first valve that is opened and closed by the first cam; a second valve that is opened and closed by the second cam; and a control unit that controls rotation of the electric motor. Each of the first cam and the second cam is symmetric with respect to a straight line passing a cam center and a cam nose.
Description
- 1. Field of the Invention
- The invention relates generally to a variable valve system for an internal combustion engine, which opens and closes, using a cam, an intake valve and an exhaust valve of an internal combustion engine. More specifically, the invention relates to a variable valve system for an internal combustion engine, which uses an electric motor to obtain power to drive a cam.
- 2. Description of the Related Art
- Japanese Patent Application Publication No. JP-A-2004-183612 describes an internal combustion engine provided with a variable valve system that can change valve opening/closing characterstics (a valve lift amount, valve opening time, valve closing time, etc.) of an intake valve and an exhaust valve. The variable valve system drives a cam using power from au electric motor instead of power transmitted from a crankshaft. Accordingly, the variable valve system can flexibly control the rotation speed and the rotation direction of the cam independently of the rotation of the crankshaft.
- With the variable valve system described in Japanese Patent Application Publication No. JP-A-2004-183612, for example, the phase of the cam can be changed by increasing/decreasing the rotation speed of the cam while the intake valve or the exhaust valve is closed (phase variable control). Meanwhile, the valve-open duration can be changed by increasing/decreasing the rotation speed of the cam while the intake valve or the exhaust valve is open (valve-open duration variable control). If the rotation of the cam is reversed before the valve is maximally lifted while the valve is open, the actual valve lift amount is less than the maximum valve lift amount (valve lift amount variable control). With this variable valve system, the valve opening/closing characteristics of the intake valve and the exhaust valve can be changed with greater flexibility.
- An electric motor that is used to drive the cams may be shared by all the cylinders. Alternatively, each cylinder may be provided with an electric motor. Also, the cylinders may be divided into multiple groups, and an electric motor may be provided to each group. When one group consists of two cylinders, an electric motor may drive the cams corresponding to two cylinders that are different in the rotation phase of the cams. In this case, if the cams are oscillated by alternately switching the rotation direction of the electric motor between the normal rotation direction and reverse rotation direction, the valve lift amount variable control described above can be performed simultaneously on the valves of the two cylinders. More specifically, the rotation direction of the electric motor is alternately switched such that each cam corresponding to one of the cylinders opens and closes the valve using, from among two ramp portions thereof, only the ramp portion used to open the valve during normal rotation of the arm, and each cam corresponding to the other cylinder opens and closes the valve using only the ramp portion used to close the valve during normal rotation of the cam.
- However, a cam commonly employed in a valve system for an internal combustion engine is formed such that the shape of the ramp portion on the valve opening side with respect to the cam nose is different from that on the valve closing side with respect to the cam nose. The ramp portion on the valve opening side is steeply inclined in order to quickly open the valve to reduce the valve-pen duration, thereby increasing the time area (the value obtained by integrating the valve opening amount) per unit valve-open duration. In contrast, the ramp portion on the valve closing side is moderately inclined in order to gradually close the valve to reduce the speed at which the valve contacts a valve seat, thereby reducing vibration and noise that are caused when the valve contacts the valve seat.
- Therefore, if the valve lift amount variable control is performed simultaneously on the valves of the two cylinders, each valve of one of the cylinders is quickly opened and closed by the steeply inclined ramp portion, and each valve of the other cylinder is gradually opened and closed by the moderately inclined ramp portion. This causes a difference in the valve lift curve between the valves of the two cylinders. As a result, the intake air amount varies between the two cylinders, causing torque fluctuation in the internal combustion engine as a whole.
- The variable valve system described above can change the valve opening/closing characteristics with great flexibility. However, the flexibility in the valve opening/closing characteristics is provided under a certain degree of constraint, because alternately switching the rotation direction of the cams causes the difference in the valve lift curve between the valves of the two cylinders.
- An object of the invention is to provide a variable valve system for an internal combustion engine, which can change valve opening/closing characteristics with greater flexibility.
- A first aspect of the invention relates to a variable valve system for an internal combustion engine. The variable valve system includes an electric motor that can be rotated in any one of the normal rotation direction and the reverse rotation direction; a first cam that is driven by the electric motor, a second cam that has the same shape as the first cam, that is driven by the electric motor, and that differs from the first cam in the rotation phase; a first valve that is opened and closed by the first cam; a second valve that is opened and closed by the second cam; and a control unit that controls rotation of the electric motor. In the variable valve system, each of the first cam and the second cam is symmetric with respect to the straight line passing the cam center and the cam nose.
- According to the first aspect, because each of the first cam and the second cam is symmetric with respect to the straight line passing the cam center and the cam nose, the same valve lift curve can be obtained regardless of whether the cam is rotated in the normal rotation direction or the reverse rotation direction. JD addition, the rotation direction and the rotation speed of each cam can be flexibly controlled by the control unit, because the electric motor is used to obtain power to drive the cams. According to the first aspect the valve opening/closing characteristics of the first valve and the second valve can be changed with greater flexibility.
- In the first aspect, the control unit may alternately switch the rotation direction of the electric motor between the normal rotation direction and the reverse rotation direction such that the first valve is opened and closed using, from among two ramp portions of the first cam, the ramp portion used to open the first valve when the electric motor is rotated in a given direction (hereinafter, referred to as the “opening ramp portion”), and the second valve is opened and closed using, from among two ramp portions of the second cam, the ramp portion used to close the second valve when the electric motor is rotated in the given direction (hereinafter, referred to as the “closing ramp portion”).
- As described above, the first valve is opened and closed using the opening ramp portion of the first cam, and the second valve is opened and closed using the closing ramp portion of the second cam. Opening/closing each of the valves using only one of the ramp portions of the corresponding cam enables the valve to be driven by a lift amount that is less than that when the cam is rotated in only one direction and the valve is opened and closed using the entirety of the cam. In addition, the first cam and the second cam have the same shape, and each of the first cam and the second cam is symmetric with respect to the straight line passing the cam center and the cam nose. Accordingly, opening/closing one of the valves using the opening ramp portion and the other valve using the closing ramp portion (using the opening ramp portion of the first cam and the closing ramp portion of second cam, or using the closing ramp portion of the first cam and the opening ramp portion of the second cam) does not cause a difference between the two valve lift curves.
- In the first aspect, the control unit may control the rotation speed of the electric motor such that the rotation speed at the start time of the open period of the first valve is higher than the rotation speed at the end time of the open period of the first valve, and the rotation speed at the start time of an open period of the second valve is higher than the rotation speed at the end time of the open period of the second valve.
- As described above, the rotation speed of the electric motor at the start time of the open period of each valve is made higher than that at the end time of the open period. Thus, the valve-pen duration of each valve can be reduced to increase the time area (the value obtained by integrating the valve opening amount) per unit valve-open duration. Accordingly, even if the ramp portions of each cam are moderately inclined to have the valve gradually contact a valve scat, the valve lift curve, according to which the valve is opened quickly and closed gradually, can be obtained.
- In the first aspect, the control unit may control the rotation speed of the electric motor such that the rotation speed at the end time of the open period of the first valve is lower than the rotation speed at the start time of the open period of the first valve, and the rotation speed at the end time of the open period of the second valve is lower than the rotation speed at the start time of the open period of the second valve.
- As described above, the first valve is opened and closed using the opening ramp portion of the first cam, and the second valve is opened and closed using the closing ramp portion of the second cam. Opening/closing each of the valves using only one of the ramp portions of the corresponding cam enables the valve to be driven by a lift amount that is less than that when the cam is rotated in only one direction and the valve is opened and dosed using the entirety of the cam. In addition, the first cam and the second cam have the same shape, and each of the first cam and the second cam is symmetric with respect to the straight line passing the cam center and the cam nose. Accordingly, opening/closing one of the valves using the opening ramp portion and the other valve using the closing ramp portion (using the opening ramp portion of the first cam and the closing ramp portion of second cam, or using the closing ramp portion of the first cam and the opening ramp portion of the second cam) does not cause a difference between the two valve lift curves.
- In the first aspect, the variable valve system may further include a camshaft used to take air into cylinders or discharge exhaust gas from the cylinders. The camshaft is driven by the electric motor controlled by the control unit. The electric motor drives the first cam provided onto the camshaft. Also, the electric motor drives the second cam provided onto the camshaft. Thus, the camshaft is directly driven by the electric motor, and the camshaft drives the first cam and the second cam. Accordingly, the variable valve system has excellent response characteristics. As a result, the variable valve system can appropriately perform the opening/closing control for an intake valve and an exhaust valve, thereby considerably improving the operating performance of the internal combustion engine.
- A second aspect of the invention relates to a variable valve system for an internal combustion engine. The variable valve system includes an electric motor that can be rotated in any one of a normal rotation direction and a reverse rotation direction; multiple cams that are provided to take air into cylinders or discharge exhaust gas from the cylinders, and that are driven by the electric motor, multiple valves that are opened and closed by the respective cams; and a control unit that controls rotation of the electric motor. Each of the cams is symmetric with respect to the straight line passing the cam center and the cam nose.
- According to the second aspect, because each valve is opened and closed by the corresponding cam that is symmetric with respect to the straight line passing the cam center and the cam nose, the same valve lift curve can be obtained regardless of whether the cam is rotated in the normal rotation direction or the reverse rotation direction.
- In addition, in the second aspect, the rotation direction and the rotation speed of each cam can be flexibly controlled by the control unit, because the electric motor is used to obtain power to drive the cams. According to the second aspect, the valve opening/closing characteristics of valves can be changed with greater flexibility.
- In the second aspect, the control unit may alternately switch the rotation direction of the electric motor between the normal rotation direction and the reverse rotation direction such that the cam opens and closes the valve using only one of two ramp portions of the cam. Because the valve can be opened and closed using only one of the two ramp portions, the valve can be driven by a lift amount that is less than that when the valve is opened and closed by rotating the cam in only one direction and using the entirety of the cam.
- In the second aspect, the control unit may control the rotation speed of the electric motor such that the rotation speed at the start time of the open period of the valve is higher than the rotation speed at the end time of the open period of the valve.
- As described above, the rotation speed of the electric motor at the start time of the open period of each valve is made higher than that at the end time of the open period. Thus, the valve-open duration of each valve can be reduced to increase the time area per unit valve-open duration. Accordingly, even if the ramp portions of each cam are moderately inclined to have the valve gradually contact a valve seat, the valve lift curve, according to which the valve is opened quickly and closed gradually, can be obtained.
- In the second aspect, the control unit may control the rotation speed of the electric motor such that the rotation speed at the end time of the open period of the valve is lower than the rotation speed at the start time of the open period of the valve.
- As described above, the rotation speed of the electric motor at the end time of the open period of each valve is made lower than that at the start time of the open period. Thus, vibration and noise that are caused when the valve contacts the valve seat can be reduced by reducing the speed at which the valve contacts the valve seat. Accordingly, even if the ramp portions of each cam are steeply inclined to increase the time area per unit valve-open duration, the valve lift curve, according to which the valve is opened quickly and closed gradually, can be obtained.
- In each of the first and second aspect, the control unit may receive data from a sensor that detects an engine operating state.
- In each of the first and second aspect, the internal combustion engine may be an in-line four-cylinder engine.
- In each of the first and second aspect, the power stroke may take place in the internal combustion engine in the order of a first cylinder, a third cylinder, a fourth cylinder, and a second cylinder.
- In each of the first and second aspect the first cam and the first valve may constitute a valve unit for the fourth cylinder, and the second cam and the second valve may constitute a valve unit for the first cylinder. In addition, the first cam and the second cam may be arranged such that the phase of the cam nose of the fast cam and the phase of the cam nose of the second cam deviate from each other by 180 degrees in the circumferential direction of the camshaft.
- The foregoing and further objects, features and advantages of the invention will become apparent from the following description of example embodiments with reference to the accompanying drawings, wherein the same or corresponding portions will be denoted by the same reference numerals and wherein:
-
FIG. 1 illustrates the perspective view of a variable valve system according to each of a first embodiment and a second embodiment of the invention; -
FIG. 2 illustrates the cross-sectional view of a camshaft taken along the plane perpendicular to the axis of the camshaft, which is used to describe the relative positional relationship between a cam corresponding to acylinder # 1 and a cam corresponding to acylinder # 4; -
FIG. 3 illustrates the graph showing the cam lift curve of the cam inFIG. 1 ; -
FIG. 4 illustrates the table showing cam lift curves that are used to describe examples of changes in the valve opening/closing characteristics obtained by the variable valve system inFIG. 1 ; -
FIGS. 5A to 5C illustrate the views showing oscillation of the cam when the valve is opened and closed by a small lift amount; -
FIG. 6 illustrates the graph showing the valve lift curve obtained by performing the motor speed control according to the second embodiment of the invention; and -
FIG. 7 illustrates the graph showing the valve lift curve obtained by performing the motor speed control according to a third embodiment of the invention. - Hereafter, a first embodiment of the invention will be described with reference to
FIGS. 1 to 5 . - [Structure of Variable Valve System]
-
FIG. 1 illustrates the perspective view showing the structure of avariable valve system 10 according to the first embodiment. Thevariable valve system 10 drives an intake valve and an exhaust valve of aninternal combustion engine 1. In the first embodiment, an in-line four-cylinder engine is employed as theinternal combustion engine 1. InFIG. 1 ,reference numerals # 1 to #4 denote first to cylinders of the internal combustion engine, respectively. The first tocylinders # 1 to #4 are arranged in series. The power stroke order of theinternal combustion engine 1 is #1→#3→#4→#2, as in the case of a commonly used internal combustion engine. In the first embodiment, thevariable valve system 10 serves as a system that drives the intake valves of the cylinders. InFIG. 1 , the structure on the exhaust valve side is not shown. However, thevariable valve system 10 may be configured as a system that drives the exhaust valves of the cylinders instead of or in addition to the intake valves of the cylinders. - In the
internal combustion engine 1 shown inFIG. 1 , each cylinder is provided with twointake valves 12.Valve shafts 14 are fixed to therespective valves 12.Valve lifters 16 are fitted to therespective valve shafts 14 at the upper portions thereof. A force of a valve spring (not shown) is applied to thevalve shaft 14. The spring force is applied such that thevalve 12 is closed. -
Cams 50,cams 52,cams 54, andcams 56 are arranged so as to contact the upper portions of thecorresponding valve lifters 16. In the first embodiment, thecams 50 denote the cams contacting thevalve lifters 16 provided to thecylinder # 1. Thecams 52 denote the cams contacting thevalve lifters 16 provided to thecylinder # 2. Thecams 54 denote the cams contacting thevalve lifters 16 provided to thecylinder # 3. Thecams 56 denote the cams contacting thevalve lifters 16 provided to thecylinder # 4. - The
cams 50 contacting thevalve lifters 16 provided to thecylinder # 1 and thecams 56 contacting thevalve lifters 16 provided to thecylinder # 4 are fixed to acamshaft 22. Thecams 52 contacting thevalve lifters 16 provided to thecylinder # 2 and thecams 54 contacting thevalve lifters 16 provided to thecylinder # 3 are fixed to acamshaft 24 that is rotatable with respect to thecamshaft 22 and that is arranged coaxially with thecamshaft 22. In the structure shown inFIG. 1 , each camshaft is shared by the cylinders where the power stroke takes place at different time. The power stroke takes place in one of these cylinders when the crankshaft has rotated by 360 degrees since the power stroke takes place in the other cylinder. These camshafts, namely, thecamshaft 22 shared by thecylinder # 1 and thecylinder # 4 and thecamshaft 24 shared by thecylinder # 2 and thecylinder # 3 are configured so as to be able to rotate and oscillate in the circumferential direction independently of each other. Thecamshaft 22 and thecamshaft 24 are rotatably supported by a support member, for example, a cylinder head (not shown). - A first driven
gear 26 is coaxially fixed to thecamshaft 22. Afirst output gear 28 is meshed with the first drivengear 26. Thefirst output gear 28 is coaxially fixed to the output shaft of afirst motor 30. Thus, torque of thefirst motor 30 can be transmitted to thecamshaft 22 via thefirst output gear 28 and the first drivengear 26. - A second driven
gear 32 is coaxially fixed to thecamshaft 24. Asecond output gear 36 is meshed with the second drivengear 32 via anintermediate gear 34. Thesecond output gear 36 is coaxially fixed to the output shaft of asecond motor 38. With this structure, torque of thesecond motor 38 can be transmitted to thecamshaft 24 via thesecond output gear 36, theintermediate gear 34, and the second drivengear 32. -
FIG. 2 illustrates the cross-sectional view of thecamshaft 22 taken along the plane perpendicular to the axis of thecamshaft 22.FIG. 2 shows the details of thecamshaft 22 inFIG. 1 . As described above, thecams 50 corresponding to thecylinder # 1 and thecams 56 corresponding to thecylinder # 4 are fixed to thecamshaft 22. As shown inFIG. 2 , thecams cam nose 50 a of thecam 50 and acam nose 56 a of thecam 56 deviate from each other by 180 degrees in the circumferential direction. - As shown in
FIG. 2 , tworamp portions cam 50. Each of theramp portions cam nose 50 a. In first embodiment the ramp portion that initially contacts thevalve lifter 16 during normal rotation of thecamshaft 22, namely, the ramp portion used to open the valve 12 (#1) is referred to as theopening ramp portion 50 b. The ramp portion that contacts thevalve lifter 16 after the apex of thecam nose 50 a contacts thevalve lifter 16, namely, the ramp portion used to close thevalve 12 is referred to as theclosing ramp portion 50 c. Similarly, the ramp portion used to open the valve 12 (#4) corresponding to the cam 56 (#4) is referred to as anopening ramp portion 56 b, and the ramp portion used to close thevalve 12 is referred to as aclosing ramp portion 56 c. - As shown in
FIG. 2 , thecams cams FIG. 3 illustrates the cam lift curve of thecam 50 corresponding to thecylinder # 1. InFIG. 3 , the lateral axis indicates the position of the cam in the circumferential direction, and the longitudinal line indicates the cam height (the height of the cam with respect to the cam base circle). InFIG. 3 , the cam lift curve is indicated using the straight line connecting the cam center to the apex of thecam nose 50 a as the Y-axis. InFIG. 3 , the cam lift curve of theopening ramp portion 50 b is shown on the left side with respect to the Y-axis, and the cam lift curve of theclosing ramp portion 50 c is shown on the right side with respect to the Y-axis. Thecam 50 is symmetric with respect to the straight line passing the cam center and the apex of thecam nose 50 a Accordingly, as shown inFIG. 3 , the cam lift curve of theopening ramp portion 50 b and the cam lift curve of theclosing ramp portion 50 c are symmetric with respect to the Y-axis. Although not shown in the figure, the cam lift curve of thecam 56 corresponding to thecylinder # 4 is similar to the cam lift curve of thecam 50 corresponding to thecylinder # 1 shown inFIG. 3 . - Although not described in detail here, the
cam 52 corresponding to thecylinder # 2 and thecam 54 corresponding to thecylinder # 3 are fixed to thecamshaft 24 such that the phases of thecams cams cam 50 corresponding to thecylinder # 1 and thecam 56 corresponding to thecylinder # 4. Each of thecams - The operation of the
variable valve system 10 is controlled by an ECU 40 (Electronic Control Unit) 40. TheECU 40 is connected to various sensors (not shown) that detect the operating state of the internal combustion engine, such as a crank angle sensor, a cam angle sensor, and an accelerator angle sensor. In addition, theECU 40 is connected to various actuators such as an actuator for thefirst motor 30, and an actuator for thesecond motor 38, etc. Also, theECU 40 stores programs used to control the rotations of thefirst motor 30 and thesecond motor 38. TheECU 40 processes the data transmitted from the various sensors, and control the rotations of themotors - [Operation of Variable Valve System]
- Next, the operation of the
variable valve system 10 will be described with reference toFIG. 4 . Here, an example where thecamshaft 22 is driven by thefirst motor 30 will be described. - The
variable valve system 10 can variously change the valve opening/closing characteristics of thevalve 12 as shown inFIG. 4 , by changing the phase of thecamshaft 22 with the crankshaft using thefirst motor 30. In this specification, the “valve opening/closing characteristics” of thevalve 12 is a generic term used to refer to the valve lift amount (maximum valve lift amount), the opening time of thevalve 12, and the closing time of thevalve 12. In addition, the “opening/closing characteristics” includes the valve-open duration that is defined by determining the opening time and the closing time, and the phase that is defined by determining the opening time (or closing time) while the valve-open duration is maintained constant. -
FIG. 4 illustrates the table showing the valve opening/closing characteristics of thevalve 12, which are variously obtained by thevariable valve system 10. More specifically, the wave-forms indicated by the solid lines inFIG. 4 show the valve lift curves obtained when thecamshaft 22 is continuously rotated in the normal rotation direction at the basic speed (the rotation speed of the camshaft is half of that of the crankshaft). The wave-forms indicated by the double-dashed lines inFIG. 4 show the valve lift curves obtained after the operation of thecamshaft 22 is changed. The lateral axis in each graph inFIG. 4 showing the valve lift curve indicates the crank angle (CA). - First, the operation for changing the “phase”, shown in
FIG. 4 , will be described. If the rotation speed of thecamshaft 22 is made higher than the basic speed while thevalve 12 is closed, the phase of thecamshaft 22 with respect of the crankshaft is changed relatively to the advance angle side. Therefore, the phase can be changed as shown inFIG. 4 . After the phase is changed, the desired phase can be maintained by returning rotation speed of thecamshaft 22 to the basic speed. On the other band, if the rotation speed of thecamshaft 22 is made lower than the basic speed while thevalve 12 is closed, the phase of thecamshaft 22 with respect to the crankshaft can be changed to the delay angle side. - The “valve-open duration” can be changed, as shown in
FIG. 4 , by making the rotation speed of thecamshaft 22 higher than the basic speed while thevalve 12 is open. However, the ratio between the rotation period of thecamshaft 22 and the rotation period of the crankshaft is maintained at 2:1 by making the rotation speed of thecamshaft 22 lower than the basic speed, while the valve is closed, by the amount corresponding to the difference between the rotation speed of thecamshaft 22 and the basic speed while thevalve 12 is open. On the contrary, the valve-open duration can be made longer than that shown by the basic wave-form indicated by the solid line, by making the rotation speed of thecamshaft 22 lower than the basic speed while thevalve 12 is open. In this case, while thevalve 12 is closed, the rotation speed of thecamshaft 22 is controlled to be higher than the basic speed by the amount corresponding to the difference between the rotation speed of thecamshaft 22 and the basic speed while thevalve 12 is open. - Next, the operation for changing the “valve-open duration and valve lift amount”, shown in
FIT 4, will be described.FIG. 4 illustrates the example in which the valve lift amount of thevalve 12 is controlled to be less than the maximum valve amount. The change can be obtained by controlling the operation of thecamshaft 22 as shown inFIGS. 5A to 5C .FIGS. 5A to 5C illustrate the operations of thecams camshaft 22 is alternately switched between the normal rotation direction and the reverse rotation direction, whereby thecams - In the operation for changing “the valve-open duration and the valve lift amount”, first, the
camshaft 22 is rotated in the clockwise direction, that is, the normal rotation direction, as shown inFIG. 5A . Thus, thecam 56 corresponding to thecylinder # 4 presses down the valve lifter 16 (#4) using theopening ramp portion 56 b. Thefirst motor 30 is stopped before the apex of thecam nose 56 a of thecam 56 contacts thevalve lifter 16. Then, the rotation direction of thefast motor 30 is switched such that thecamshaft 22 is rotated in the counterclockwise direction, that is, the reverse rotation direction. Thus, thecamshaft 22 is rotated in the reverse rotation direction, and the condition shown inFIG. 5B is achieved. - Thus, the
cam 56 oscillates while only theopening ramp portion 56 b, from among the tworamp portions valve 12 of thecylinder # 4 is operated according to the valve lift curve defined by the cam lift curve of theopening ramp portion 56 b of thecam 56. - Next, the
camshaft 22 is further rotated in the reverse rotation direction. Then, as shown inFIG. 5C , thecam 50 corresponding to thecylinder # 1 presses down the valve lifter 16 (#1) using theclosing ramp portion 50 c. Thefirst motor 30 is stopped before thecam nose 50 a contacts the valve lifter 16 (#1). Theo, the rotation direction of thefirst motor 30 is switched again, and thecamshaft 22 is rotated in the normal rotation direction until the condition shown inFIG. 5B is achieved. Thus, thecam 50 oscillates while only theclosing ramp portion 50 c, from among the tworamp portions valve 12 of thecylinder # 1 is operated according to the valve lift curve defined by the cam lift curve of theclosing ramp portion 50 c of thecam 50. - The
cams valves 12 of thecylinder # 1 and thecylinder # 4 can be simultaneously changed by thecams camshaft 22. At this time, the valve lift amounts of thevalves 12 can be appropriately changed by appropriately changing the amounts of oscillation of thecams cams FIG. 4 , by appropriately changing the rotation speed of thefirst motor 30. When the operation for changing “the valve-open duration and the valve lift amount” is performed and when the operation for changing the “valve lift amount” is performed, the oscillation period of thecams - In the first embodiment described above, the
valve 12 of thecylinder # 4 is opened and closed using theopening ramp portion 56 b of thecam 56 and thevalve 12 of thecylinder # 1 is opened and closed using theclosing ramp portion 50 c of thecam 50 by alternately switching the rotation direction of thefirst motor 30 to periodically oscillate thecams - Also, in the first embodiment, the
valve 12 of thecylinder # 1 and thevalve 12 of thecylinder # 4 are opened and closed using only theclosing ramp portion 50 c of thecam 50 and theopening ramp portion 56 b of thecam 56, respectively. Accordingly, each of thevalves 12 can be operated by a lift amount less than that when thevalves 12 are opened and closed using the entireties of thecams camshaft 22 only in the normal rotation direction. - As shown in
FIG. 2 , thecams cams cam noses valves 12 are operated using theclosing ramp portion 50 c of thecam 50 and theopening ramp portion 56 b of thecam 56, the valve lift curves of thevalves 12 do not differ from each other. Accordingly, even if the valve lift amount of thevalves 12 is changed, the intake air amount does not differ between thecylinder # 1 and thecylinder # 4. - With the
variable valve system 10 according to the first embodiment described above, the operation of thecams camshaft 22 is appropriately controlled by controlling thefirst motor 30 using theECU 40. Also, each of thecams cams variable valve system 10 according to the first embodiment, the rotation direction of thecamshaft 22 is not limited to a certain direction, and the operation of thecams camshaft 22. Thus, the valve opening/closing characteristics of thevalve 12 can be changed with great flexibility. - In the operation for changing the valve lift amount according to the first embodiment, the
opening ramp portion 56 b is used in thecam 56 corresponding to thecylinder # 4, and theclosing ramp portion 50 c is used in thecam 50 corresponding to thecylinder # 1. However, theclosing ramp portion 56 c may be used in thecam 56 corresponding to thecylinder # 4, and theopening ramp portion 50 b may be used in thecam 50 corresponding to thecylinder # 1. Which ramp portion, from among the opening ramp portion and the closing ramp portion, should be used may be determined depending on the rotation position of each of thecams - In the case of the
cylinder # 2 and thecylinder # 3, thecams cams camshaft 24 is rotated in the normal rotation direction or reverse rotation direction. Although not descried in detail here, the operation of thecams second motor 38, the rotation speed and the rotation direction of thecamshaft 24 and the angle by which thecams valve 12 can be changed with great flexibility. - Next, a second embodiment of the invention will be described with reference to FIG. 6.
- The structure of a variable valve system according to the second embodiment is shown in
FIG. 1 , as in the first embodiment. The second embodiment is different from the first embodiment in the control of the rotation speed of themotors FIG. 6 illustrates the graph showing the valve lift curve that is obtained by controlling the rotation speed of themotors ECU 40. - As described in the first embodiment, each of the
cams motors valve 12 is equal to the rotation speed at the end time of the open period of thevalve 12. However, thevalve 12 is required to be quickly opened to quickly reduce the valve-open duration, thereby increasing the time area (the value obtained by integrating the valve opening amount) per unit valve-open duration. Meanwhile, thevalve 12 is required to be gradually closed to reduce the speed at which thevalve 12 contacts the valve seat, thereby reducing vibration and noise that are caused when thevalve 12 contacts the valve seat. However, these two requirements contradict each other. Accordingly, if the shape of the cam is defined such that one of these requirements is fulfilled, the other requirement cannot be fulfilled. - The second embodiment is made to fulfill both the requirement concerning the speed at which the
valve 12 is opened and the requirement concerning the speed at which thevalve 12 is closed. According to the second embodiment, thevalve 12 is quickly opened by appropriately selecting the shape of the cam, and thevalve 12 is gradually closed by controlling the rotation speed of themotors cams motors valve 12 is made lower than the rotation speed NCopen at the start time of the open period of thevalve 12. - Thus, the valve lift curve, indicated by the slid line in
FIG. 6 , according to which thevalve 12 opens quickly and closes gradually, can be obtained. As a result, the time area per unit valve-open duration can be increased by reducing the valve-open duration of thevalve 12, while vibration and noise that are caused when thevalve 12 contacts the valve seat can be reduced by reducing the speed at which thevalve 12 contacts the valve seat. When the rotation speed of themotors valve 12, the valve lift curve at the end time of the open period of thevalve 12 is as indicated by the dashed line inFIG. 6 . - The control descried above can be applied not only to the case where each of the
cams cams motors - Next, a third embodiment of the invention will be described with reference to
FIG. 7 . - The variable valve system according to the third embodiment, as well as the variable valve system according to the second embodiment, is characterized in that both the requirement concerning the speed at which the
valve 12 is opened and the requirement concerning the speed at which thevalve 12 is closed are fulfilled by appropriately selecting the shape of the cam and controlling the rotation speed of themotors FIG. 7 illustrates the graph showing the valve lift curve obtained by controlling the rotation speed of themotors ECU 40. - In the third embodiment, both of the requirements are fulfilled in the approach opposite to that in the second embodiment. According to the third embodiment, the
valve 12 is closed gradually by appropriately selecting the shape of the cam, and thevalve 12 is opened quickly by controlling the rotation speed of themotors cams valve 12 gradually contact the valve seat. In addition, the rotation speed NCopen of themotors valve 12 is made higher than the rotation speed NCclose at the end time of the open period of thevalve 12. - Thus, the valve lift curve, indicated by the solid line in
FIG. 7 , according to which thevalve 12 quickly opens and gradually closes, can be obtained as in the second embodiment. As a result, the the area per unit valve-open duration can be increased by reducing the valve-pen duration of thevalve 12, while vibration and noise which are caused when thevalve 12 contacts the valve seat can be reduced by reducing the speed at which thevalve 12 contacts the valve seat. When the rotation speed of themotors valve 12, the valve lift curve at the start time of the open period of thevalve 12 is as indicated by the dashed line shown inFIG. 7 . - The control described above can be applied not only to the case where each of the
cams cams motors - [Others]
- While the invention has been described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the exemplary embodiments. To the contrary, the invention is intended to cover various modifications and equivalent arrangements. For example, the invention can be realized according to the following modified examples.
- In the embodiments described above, the cams corresponding to two cylinders are driven by one motor. However, the cams corresponding to one cylinder may be driven by one motor. In this case as well, the shape of each cam is symmetric with respect to the straight line passing the cam center and the apex of the cam nose. Thus, the same valve lift curve can be obtained regardless of whether the cam is rotated in the normal rotation direction or the reverse rotation direction. Accordingly, the rotation direction and the rotation speed of the cam can be flexibly set, whereby the valve opening/closing characteristics of the valves can be changed with great flexibility.
- In the embodiments described above, the power stroke order of the
internal combustion engine 1 is #1→#3→#4→#2. However, the invention can be applied to an internal combustion engine where the power stroke order is #1→#2→#4→#3.
Claims (13)
1. A variable valve system for an internal combustion engine, comprising:
an electric motor that can be rotated in any one of a normal rotation direction and a reverse rotation direction;
a first cam that is driven by the electric motor;
a second cam that has a same shape as the first cam, that is driven by the electric motor, and that differs from the first cam in a rotation phase;
a first valve that is provided to a first cylinder and that is opened and closed by the first cam;
a second valve that is provided to a second cylinder and that is opened and closed by the second cam; and
a control unit that controls rotation of the electric motor, wherein
each of the first cam and the second cam is symmetric with respect to a straight line passing a cam center and a cam nose.
2. The variable valve system for an internal combustion engine according to claim 1 , wherein
the control unit alternately switches a rotation direction of the electric motor between the normal rotation direction and the reverse rotation direction such that the first valve is opened and closed using, from among two ramp portions of the first cam, the ramp portion used to open the first valve when the electric motor is rotated in a given direction, and the second valve is opened and closed using, from among two ramp portions of the second cam, the ramp portion used to close the second valve when the electric motor is rotated in the given direction.
3. The variable valve system for an internal combustion engine according to claim 1 , wherein
the control unit controls a rotation speed of the electric motor such that the rotation speed at a start time of an open period of the first valve is higher than the rotation speed at an end time of the open period of the first valve, and the rotation speed at a start time of an open period of the second valve is higher than the rotation speed at an end time of the open period of the second valve.
4. The variable valve system for an internal combustion engine according to claim 1 , wherein
the control unit controls a rotation speed of the electric motor such that the rotation speed at an end time of an open period of the first valve is lower than the rotation speed at a start time of the open period of the first valve, and the rotation speed at an end time of an open period of the second valve is lower than the rotation speed at a start time of the open period of the second valve.
5. The variable valve system for an internal combustion engine according to claim 1 , further comprising:
a camshaft used to take air into cylinders or discharge exhaust gas from the cylinders, wherein
the camshaft is driven by the electric motor controlled by the control unit,
the electric motor drives the first cam provided onto the camshaft; and
the electric motor drives the second cam provided onto the camshaft.
6. A variable valve system for an internal combustion engine, comprising:
an electric motor that can be rotated in any one of a normal rotation direction and a reverse rotation direction;
multiple cams that are driven by the electric motor;
multiple valves that are provided to take air into cylinders or discharge exhaust gas from the cylinders and that are opened and closed by the respective cams; and
a control unit that controls rotation of the electric motor, wherein
each of the cams is symmetric with respect to a straight line passing a cam center and a cam nose.
7. The variable valve system for an internal combustion engine according to claim 6 , wherein
the control unit alternately switches a rotation direction of the electric motor between the normal rotation direction and the reverse rotation direction such that the cam opens and closes the valve using only one of two ramp portions of the cam.
8. The variable valve system for an internal combustion engine according to claim 6 , wherein
the control unit controls a rotation speed of the electric motor such that the rotation speed at a start time of an open period of the valve is higher than the rotation speed at an end time of the open period of the valve.
9. The variable valve system for an internal combustion engine according to claim 6 , wherein
the control unit controls a rotation speed of the electric motor such that the rotation speed at an end time of an open period of the valve is lower than the rotation speed at a start time of the open period of the valve.
10. The variable valve system for an internal combustion engine according to claim 2 , wherein
the control unit controls a rotation speed of the electric motor such that the rotation speed at a start time of an open period of the first valve is higher than the rotation speed at an end time of the open period of the first valve, and the rotation speed at a start time of an open period of the second valve is higher than the rotation speed at an end time of the open period of the second valve.
11. The variable valve system for an internal combustion engine according to claim 2 , wherein
the control unit controls a rotation speed of the electric motor such that the rotation speed at an end time of an open period of the first valve is lower than the rotation speed at a start time of the open period of the first valve, and the rotation speed at an end time of an open period of the second valve is lower than the rotation speed at a start time of the open period of the second valve.
12. The variable valve system for an internal combustion engine according to claim 7 , wherein
the control unit controls a rotation speed of the electric motor such that the rotation speed at a start time of an open period of the valve is higher than the rotation speed at an end time of the open period of the valve.
13. The variable valve system for an internal combustion engine according to claim 7 , wherein
the control unit controls a rotation speed of the electric motor such that the rotation speed at an end time of an open period of the valve is lower than the rotation speed at a start time of the open period of the valve.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2005-203833 | 2005-07-13 | ||
JP2005203833A JP2007023814A (en) | 2005-07-13 | 2005-07-13 | Variable valve gear for internal combustion engine |
PCT/IB2006/001911 WO2007007168A1 (en) | 2005-07-13 | 2006-07-11 | Variable valve system for internal combustion engine |
Publications (1)
Publication Number | Publication Date |
---|---|
US20090107431A1 true US20090107431A1 (en) | 2009-04-30 |
Family
ID=37056402
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/988,181 Abandoned US20090107431A1 (en) | 2005-07-13 | 2006-07-11 | Variable Valve System For Internal Combustion Engine |
Country Status (5)
Country | Link |
---|---|
US (1) | US20090107431A1 (en) |
EP (1) | EP1904719A1 (en) |
JP (1) | JP2007023814A (en) |
CN (1) | CN101223338A (en) |
WO (1) | WO2007007168A1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20120137998A1 (en) * | 2010-12-06 | 2012-06-07 | Kia Motors Corporation | Variable valve device |
US20120158267A1 (en) * | 2010-01-15 | 2012-06-21 | Toyota Jidosha Kabushiki Kaisha | Valve working angle variable system |
US20150247467A1 (en) * | 2012-10-30 | 2015-09-03 | Toyota Jidosha Kabushiki Kaisha | Control apparatus of internal combustion engine |
CN106103945A (en) * | 2014-03-25 | 2016-11-09 | 斗山英维高株式会社 | Electromotor |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9689326B2 (en) | 2015-06-04 | 2017-06-27 | Hyundai America Technical Center, Inc. | Exhaust gas recirculation system with paired cylinders |
CN107489536B (en) * | 2016-06-09 | 2022-05-10 | 福特环球技术公司 | System for deactivating engine cylinders |
GB201616956D0 (en) * | 2016-10-06 | 2016-11-23 | Jaguar Land Rover Limited | Method of controlling a valve train |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4610224A (en) * | 1984-12-20 | 1986-09-09 | Toyota Jidosha Kabushiki Kaisha | Configuration for V type double overhead cam shaft engine utilizing interchangable intake cam shafts and interchangable exhaust cam shafts |
US5215048A (en) * | 1989-10-04 | 1993-06-01 | Ford Motor Company | Camshaft for multi-valve internal combustion engine |
US20050098129A1 (en) * | 2003-08-12 | 2005-05-12 | Toyota Jidosha Kabushiki Kaisha | Valve gear of internal combustion engine |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
BE470962A (en) * | ||||
DE818274C (en) * | 1947-02-24 | 1951-10-25 | Austin Motor Co Ltd | Cams for controlling the valves of internal combustion engines |
DE3624827A1 (en) * | 1986-07-23 | 1988-02-04 | Sueddeutsche Kolbenbolzenfabri | ADJUSTMENT FOR A CAMSHAFT FOR CONTROLLING THE GAS INLET AND EXHAUST VALVES OF COMBUSTION ENGINES |
JP4082197B2 (en) * | 2002-12-05 | 2008-04-30 | トヨタ自動車株式会社 | Valve drive system for internal combustion engine |
JP4007320B2 (en) * | 2003-12-17 | 2007-11-14 | トヨタ自動車株式会社 | Valve operating device for internal combustion engine |
US7568457B2 (en) * | 2004-06-03 | 2009-08-04 | Toyota Jidosha Kabushiki Kaisha | Valve driving device for multi-cylinder internal combustion engine |
-
2005
- 2005-07-13 JP JP2005203833A patent/JP2007023814A/en not_active Withdrawn
-
2006
- 2006-07-11 WO PCT/IB2006/001911 patent/WO2007007168A1/en not_active Application Discontinuation
- 2006-07-11 US US11/988,181 patent/US20090107431A1/en not_active Abandoned
- 2006-07-11 CN CNA2006800257029A patent/CN101223338A/en active Pending
- 2006-07-11 EP EP06779851A patent/EP1904719A1/en not_active Withdrawn
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4610224A (en) * | 1984-12-20 | 1986-09-09 | Toyota Jidosha Kabushiki Kaisha | Configuration for V type double overhead cam shaft engine utilizing interchangable intake cam shafts and interchangable exhaust cam shafts |
US5215048A (en) * | 1989-10-04 | 1993-06-01 | Ford Motor Company | Camshaft for multi-valve internal combustion engine |
US20050098129A1 (en) * | 2003-08-12 | 2005-05-12 | Toyota Jidosha Kabushiki Kaisha | Valve gear of internal combustion engine |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20120158267A1 (en) * | 2010-01-15 | 2012-06-21 | Toyota Jidosha Kabushiki Kaisha | Valve working angle variable system |
US9850824B2 (en) * | 2010-01-15 | 2017-12-26 | Toyota Jidosha Kabushiki Kaisha | Valve working angle variable system |
US20120137998A1 (en) * | 2010-12-06 | 2012-06-07 | Kia Motors Corporation | Variable valve device |
US8555840B2 (en) * | 2010-12-06 | 2013-10-15 | Hyundai Motor Company | Variable valve device |
US20150247467A1 (en) * | 2012-10-30 | 2015-09-03 | Toyota Jidosha Kabushiki Kaisha | Control apparatus of internal combustion engine |
US9739211B2 (en) * | 2012-10-30 | 2017-08-22 | Toyota Jidosha Kabushiki Kaisha | Control apparatus of internal combustion engine |
CN106103945A (en) * | 2014-03-25 | 2016-11-09 | 斗山英维高株式会社 | Electromotor |
US20170096948A1 (en) * | 2014-03-25 | 2017-04-06 | Doosan Infracore Co., Ltd. | Engine |
US10107209B2 (en) * | 2014-03-25 | 2018-10-23 | Doosan Infracore Co., Ltd. | Engine |
Also Published As
Publication number | Publication date |
---|---|
JP2007023814A (en) | 2007-02-01 |
CN101223338A (en) | 2008-07-16 |
WO2007007168A1 (en) | 2007-01-18 |
EP1904719A1 (en) | 2008-04-02 |
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Legal Events
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AS | Assignment |
Owner name: TOYOTA JIDOSHA KABUSHIKI KAISHA, JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:EZAKI, SHUICHI;REEL/FRAME:020342/0196 Effective date: 20071116 |
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STCB | Information on status: application discontinuation |
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