JP5913065B2 - Starter for internal combustion engine - Google Patents

Description

  The present invention relates to a starter for an internal combustion engine.

  When starting the internal combustion engine, cranking is performed in which the rotating electrical machine is driven to drive the internal combustion engine to a predetermined rotational speed. In the process of increasing the rotational speed of the internal combustion engine, the rotational speed may overlap with the resonance band of the drive system. A drive system refers to a group of devices that transmit the power of a prime mover to a load, and includes, for example, an internal combustion engine, a shaft, a flywheel, and a torsion damper. When the rotational speed of the internal combustion engine overlaps with the resonance band of the drive system and resonance of the drive system occurs, the vibration and noise of the vehicle equipped with the drive system increase, and the ride comfort of the occupant deteriorates.

  Therefore, for example, in Patent Document 1 below, the rotational speed of the internal combustion engine is controlled so as to pass through the resonance band of the drive system quickly. Specifically, when the rotational speed of the internal combustion engine reaches the resonance band, the cranking torque of the rotating electrical machine is temporarily increased to rapidly increase the rotational speed of the internal combustion engine.

JP-A-11-117840

  By the way, when the cranking torque of the rotating electrical machine is increased, the power consumption of the battery that supplies power to the rotating electrical machine is increased accordingly. If so, the capacity of the battery must be increased in preparation for an increase in cranking torque, which causes an increase in the size of the battery. Therefore, an object of the present invention is to provide a starter for an internal combustion engine that can alleviate the deterioration of the ride comfort without increasing the cranking torque.

  The present invention relates to a starting device for an internal combustion engine. The starting device includes: a rotating electric machine that rotates the internal combustion engine during a starting period of the internal combustion engine; a first wheel that rotates integrally with the internal combustion engine and a shaft that transmits a driving force of the rotating electric machine; and the first wheel. A flywheel comprising: a second wheel that can rotate relative to the second wheel; and a variable viscosity fluid sealed between the first wheel and the second wheel; and a controller that adjusts the viscosity of the variable viscosity fluid; Is provided. The control unit increases the viscosity of the viscosity variable fluid during a start-up period of the internal combustion engine, and causes the viscosity variable fluid to absorb vibration generated in the flywheel as the internal combustion engine is driven to rotate.

  In the above invention, it is preferable that the controller increases the viscosity of the variable viscosity fluid in accordance with an increase in the rotational speed of the internal combustion engine.

  In the above invention, it is preferable that the controller does not increase the viscosity of the variable viscosity fluid until the rotational speed of the internal combustion engine reaches a first rotational speed.

  As another aspect of the present invention, an internal combustion engine starter is integrated with a rotating electrical machine that rotates the internal combustion engine during a start period of the internal combustion engine, and a shaft that transmits the driving force of the internal combustion engine and the rotating electrical machine. A flywheel comprising: a rotating first wheel; a second wheel rotatable relative to the first wheel; and a variable viscosity fluid enclosed between the first wheel and the second wheel; and the variable viscosity And a controller that adjusts the viscosity of the fluid. The control unit shifts the resonance frequency of the drive system including the internal combustion engine and the flywheel to a low frequency side by increasing the viscosity of the viscosity variable fluid during the start-up period of the internal combustion engine.

  According to the present invention, it is possible to alleviate the deterioration in riding comfort without increasing the cranking torque.

1 is a block diagram of a vehicle drive device including a starter for an internal combustion engine according to the present embodiment. It is side surface sectional drawing of the flywheel which concerns on this Embodiment. It is side surface sectional drawing which shows another example of the flywheel which concerns on this Embodiment. It is an expanded side sectional view of the flywheel concerning this embodiment. It is a graph showing the relationship between the supply current and the viscosity of a viscosity variable fluid of the flywheel which concerns on this Embodiment. It is a graph which shows the vibration characteristic of the drive system based on this Embodiment. It is a graph which shows the vibration characteristic of the drive system based on this Embodiment. 4 is a time chart of start control of the internal combustion engine according to the present embodiment. 4 is a time chart of start control of the internal combustion engine according to the present embodiment. 3 is a flowchart of internal combustion engine start control according to the present embodiment. 4 is a time chart of start control of the internal combustion engine according to the present embodiment. 4 is a time chart of start control of the internal combustion engine according to the present embodiment. 3 is a flowchart of internal combustion engine start control according to the present embodiment. 4 is a time chart of start control of the internal combustion engine according to the present embodiment. 4 is a time chart of start control of the internal combustion engine according to the present embodiment.

  FIG. 1 illustrates a vehicle drive device 10. The drive device 10 includes an internal combustion engine 20, rotating electrical machines MG <b> 1 and MG <b> 2, a shaft 14, a flywheel 16, a control unit 18, a torsion damper 24, a power split mechanism 15, and a reduction mechanism 17. A part of the driving device 10 also serves as a starting device that starts the internal combustion engine 20. Specifically, the starting device according to the present embodiment includes a rotating electrical machine MG1, a shaft 14, a flywheel 16, and a control unit 18.

  The internal combustion engine 20 may be a reciprocating engine having a plurality of cylinders (not shown). The rotating electrical machine MG1 rotates the internal combustion engine 20 when the internal combustion engine 20 is started (cranking). Moreover, the rotary electric machine MG1 may have a function of a generator that is rotated by the internal combustion engine 20 that rotates independently after being started to generate electric power. The rotating electrical machine MG2 is a prime mover that drives the drive wheels 19 in cooperation with the internal combustion engine 20. The rotating electrical machine MG2 may have a function of a generator that generates electric power by being rotated by the drive wheels 19 when the vehicle is decelerated. The rotating electrical machines MG1 and MG2 are constituted by, for example, permanent magnet motors.

  The shaft 14 is a drive shaft that transmits the drive force of the internal combustion engine 20 and the rotating electrical machine MG1. The shaft 14 may include a crankshaft 22 of the internal combustion engine 20. The torsion damper 24 absorbs pulsation of engine torque. The torsion damper 24 is provided between the input side member connected to the internal combustion engine 20 side of the shaft 14, the output side member connected to the drive wheel 19 side of the shaft 14, and the input side member and the output side member. It may be made of an elastic material.

  The power split mechanism 15 splits the power of the internal combustion engine 20 into power for driving the rotary electric machine MG1 and power for driving the drive wheels 19. The power split mechanism 15 includes a sun gear 15a, a planetary carrier 15b, and a ring gear 15c. The sun gear 15 a is connected to the rotating electrical machine MG 1, the planetary carrier 15 b is connected to the shaft 14 (and the internal combustion engine 20), and the ring gear 15 c is connected to the drive wheel 19. Further, the reduction mechanism 17 transmits the power to the drive wheels 19 by decelerating the rotation of the rotating electrical machine MG2 and amplifying the drive torque. As with the power split mechanism 15, the reduction mechanism 17 includes a sun gear 17a, a planetary carrier 17b, and a ring gear 17c. The sun gear 17a is connected to the rotating electrical machine MG2, the planetary carrier 17b is fixed, and the ring gear 17c is connected to the drive wheel 19.

  FIG. 2 illustrates a side cross-sectional view of the flywheel 16. The flywheel 16 is assembled to the shaft 14 and suppresses rotational fluctuations of the shaft 14. The flywheel 16 includes a first wheel 26, a second wheel 28, a variable viscosity fluid 30, and a stator coil 32.

  The first wheel 26 includes a disc portion 34, a boss portion 36, and a power transmission plate portion 42. The boss portion 36 is a member fixed to the shaft 14 and is formed in a cylindrical shape. Further, the inner diameter is formed so as to be substantially equal to the diameter of the fixed surface of the shaft 14. For example, when the boss portion 36 is fixed to the shaft 14 with a fastening member such as a bolt, the inner diameter of the boss portion 36 is formed to be equal to or larger than the diameter of the fixing surface of the shaft 14. Further, when the boss portion 36 is fixed to the shaft 14 by press fitting or shrink fitting, the inner diameter of the boss portion 36 is formed to be slightly smaller than the diameter of the fixing surface of the shaft 14.

  The disc portion 34 is a substantially disc-shaped member that extends radially outward from the outer peripheral surface of the boss portion 36. The disc part 34 may be provided on the end face side of the boss part 36. Moreover, the outer peripheral side of the disc part 34 may be formed thicker than the inner peripheral side. The power transmission plate portion 42 is a substantially disk-shaped member that extends radially outward from the outer peripheral surface of the boss portion 36. The power transmission plate portion 42 may be provided at the center portion of the boss portion 36.

  The second wheel 28 includes a cylindrical portion 44 and a disc portion 46. The cylindrical portion 44 is arranged to be coaxial with the boss portion 36 of the first wheel 26 and has a diameter that is slightly larger than the boss portion 36, and the inner diameter thereof is larger than the outer diameter of the boss portion 36 of the first wheel 26. Is formed. Further, the axial length of the cylindrical portion 44 is shorter than the boss portion 36 of the first wheel 26. Further, the cylindrical portion 44 is provided with a groove portion 48 formed from the inner peripheral surface toward the radially outer side and extending in the circumferential direction over the entire circumference. The width of the groove portion 48 is formed wider than the thickness of the power transmission plate portion 42 of the first wheel 26. Further, the groove depth of the groove portion 48 is formed deeper than the diameter of the power transmission plate portion 42.

  Further, a spacer 49 made of a non-magnetic material is provided on the outer peripheral side of the groove portion 48 so as to face the coil 50 of the stator coil 32. By providing the non-magnetic spacer 49 between the coil 50 and the groove 48, the magnetic flux generated from the coil 50 bypasses the spacer 49 and passes through the variable viscosity fluid 30 in the groove 48.

  The second wheel 28 is combined around the first wheel 26 so as to be rotatable relative to the first wheel 26 and the shaft 14. For example, the cylindrical portion 44 of the second wheel 28 is assembled to the outer periphery of the boss portion 36 of the first wheel 26 via the bearing 31. At the time of this assembly, the power transmission plate portion 42 of the first wheel 26 is inserted into the groove portion 48 of the second wheel 28. The second wheel 28 may be formed of a divided body so that the power transmission plate portion 42 can be inserted into the groove portion 48. For example, you may comprise the 2nd wheel 28 from the bipartite body of a semicircular disk. Further, there is a gap between the power transmission plate portion 42 and the wall surface of the groove portion 48 so that the power transmission plate portion 42 does not contact the wall surface of the groove portion 48 while the first wheel 26 makes one rotation around the rotation axis Ax. Provided.

  The variable viscosity fluid 30 is enclosed between the first wheel 26 and the second wheel 28. Specifically, the variable viscosity fluid 30 is filled in the groove portion 48 of the second wheel 28. Further, in order to prevent the viscosity variable fluid 30 from leaking from the groove portion 48, the seal members 38 </ b> A and 38 </ b> B are interposed between the boss portion 36 of the first wheel 26 and the cylindrical portion 44 of the second wheel 28 with the groove portion 48 interposed therebetween. Is provided. The contact surfaces of the seal members 38A and 38B with the cylindrical portion 44 of the second wheel 28 are slidable.

  The stator coil 32 applies a magnetic field to the viscosity variable fluid 30. The stator coil 32 includes a coil 50 and a holding part 52. The coil 50 is provided on the outer peripheral side of the groove portion 48 over the entire circumference without contacting the second wheel 28. For example, the coil 50 faces the outer peripheral surface of the cylindrical portion 44 of the second wheel 28 via the clearance C. The holding part 52 is a holding member for the coil 50. The holding part 52 is fixed to the cylinder block 56.

  Instead of the flywheel 16 of FIG. 2, a flywheel 16 as shown in FIG. 3 may be used. In the flywheel of FIG. 3, a step portion 61 is formed on the disc portion 34 of the first wheel 26 over the entire circumference. The first wheel 26 is fixed to the shaft 14 and rotates integrally with the shaft 14. The second wheel 28 has a substantially disc shape, and is provided with an annular protrusion 65 extending in the radial direction from the center of the diameter.

  The second wheel 28 is combined around the first wheel 26 so as to be rotatable relative to the first wheel 26 and the shaft 14. Specifically, the second wheel 28 is rotatably assembled to the first wheel 26 by sandwiching the bearing 31 between the step portion 61 of the first wheel 26 and the protrusion 65 of the second wheel 28.

  In addition, the variable viscosity fluid 30 is sealed in a region sandwiched between the disc portion 34 of the first wheel 26 on the inner diameter side from the step portion 61 and the second wheel 28 on the inner diameter side from the protrusion 65. In order to prevent leakage of the viscosity variable fluid 30, a seal member 38 is provided between the outer peripheral surface of the boss portion 36 of the first wheel 26 and the inner peripheral surface of the second wheel 28. Further, the gap between the step portion 61 and the projection portion 65 is closed by the bearing 31.

  The coil 50 of the stator coil 32 is adjacent to the variable viscosity fluid 30 along the rotation axis Ax. Specifically, the coil 50 faces the variable viscosity fluid 30 with the clearance C between the second wheel 28 and the second wheel 28 interposed therebetween. The holding portion 52 of the stator coil 32 holds the coil 50 in a non-contact manner with the first wheel 26 and the second wheel 28.

  Next, a change in viscosity of the viscosity variable fluid 30 and a change in vibration characteristics of the flywheel 16 and peripheral devices due to the change will be described with reference to FIG. In FIG. 4, the flywheel 16 shown in FIG. 2 is taken as an example. When a current is supplied to the stator coil 32, a magnetic field is generated around the stator coil 32. The magnetic flux a by this magnetic field flows around the stator coil 32. Specifically, the cylinder of the second wheel 28 passes through the cylindrical portion 44 of the second wheel 28, the power transmission plate portion 42 of the first wheel 26, the variable viscosity fluid 30, and the holding portion 52 of the stator coil 32. Flows back to section 44. This magnetic field acts on the variable viscosity fluid 30 to increase the viscosity of the variable viscosity fluid 30.

  FIG. 5 shows the relationship between the amount of current supplied to the stator coil 32 and the viscosity of the viscosity variable fluid 30. As the amount of current supplied to the stator coil 32 increases, the magnetic field applied to the variable viscosity fluid 30 increases and the viscosity of the variable viscosity fluid 30 increases.

  When the viscosity of the variable viscosity fluid 30 increases, the shearing force or the frictional force acting on the opposing surfaces of the power transmission plate portion 42 of the first wheel 26 and the cylindrical portion 44 of the second wheel 28 has no magnetic field. Increased compared to As a result, the second wheel 28 follows the first wheel 26. When the viscosity of the viscosity variable fluid is further increased, the first wheel 26 and the second wheel 28 are coupled to each other so as to rotate integrally. In the process of increasing the coupling force between the first wheel 26 and the second wheel 28, the moment of inertia of the flywheel 16 increases. Thus, by changing the magnetic field applied to the viscosity variable fluid 30, in other words, by changing the amount of current supplied to the stator coil 32, the moment of inertia of the flywheel 16 can be changed.

  Further, the vibration characteristics of the drive system including the flywheel 16 change as the viscosity of the viscosity variable fluid 30 changes. FIG. 6 shows the vibration characteristics of the drive system for each viscosity of the viscosity variable fluid 30. Here, the drive system refers to a group of devices that transmit the power of the prime mover to the load. For example, the drive system refers to a system including the flywheel 16, the internal combustion engine 20, the rotating electrical machine MG1, the shaft 14, and the torsion damper 24. . Since such a drive system includes the rotating electrical machine MG1, the inertia moment of the rotor has an effect, and the resonance frequency tends to be generated on the low frequency side as compared with a drive device including only an internal combustion engine as a prime mover. Further, in the drive device 10, the shaft 14 and the planetary carrier 15b extending beyond the rotating electrical machine MG1 to the power split mechanism 15 are also a factor in reducing the resonance frequency. For this reason, there may be a system in which a resonance frequency is generated in a region below the idling speed of the internal combustion engine 20, that is, from the stop state (rotation speed 0) of the internal combustion engine 20 to the speed at which the engine can be operated independently. is there. In the following, the rotational speed of the internal combustion engine 20 refers to the number of rotations of the internal combustion engine 20 per unit time, and is assumed to be a unit of a dimension equal to the frequency. Specifically, the rotational speed Ne and the frequency Frq have a relationship of Frq = nNe / 120, where n is the number of cylinders of the internal combustion engine 20.

In FIG. 6, the horizontal axis indicates the frequency, and the vertical axis indicates the vibration characteristic gain. A characteristic 1 is a vibration characteristic of the drive system when a magnetic field is not applied to the variable viscosity fluid 30, that is, when no current is supplied to the stator coil 32. Characteristics 2 to 4 are vibration characteristics of the drive system when a current is supplied to the stator coil 32 and a magnetic field is applied to the variable viscosity fluid 30. When the currents in the characteristics 1 to 4 are expressed by I _{C1 to} I _C4 , I _C1 (= 0) <I _C2 <I _C3 <I _C4 . Further, it is assumed that the current I _C4 is an amount of current that causes the variable viscosity fluid 30 to completely couple the first wheel 26 and the second wheel 28 so that both wheels rotate integrally. The characteristic 4 may be considered to be the same as the characteristic of a conventional flywheel that does not include the variable viscosity fluid 30.

The following features are derived from the characteristics 1 to 4 in FIG.
Feature 1: As the amount of current increases, the gain once decreases and then increases.
Feature 2: As the amount of current increases, the resonance frequency (the peak frequency of the gain) shifts to the low frequency side.

  The reason for the feature 1 is a change in the viscosity of the viscosity variable fluid 30. In other words, supplying the current to the stator coil 32 increases the viscosity of the variable viscosity fluid 30. At this time, the variable viscosity fluid 30 serves as a viscous damper that absorbs vibration. Since the vibration is absorbed, the gain of the vibration is reduced. Further, when the viscosity increases (hardens), the function of absorbing vibration decreases. From this, the vibration absorption characteristic becomes the highest in the characteristics 2 and 3 during the transition from the characteristic 1 having the lowest viscosity to the characteristic 4 having the highest viscosity.

  The reason for the feature 2 is an increase in the moment of inertia of the flywheel 16. As described above, as the amount of current to the stator coil 32 increases, the coupling force between the first wheel 26 and the second wheel 28 increases and the moment of inertia of the flywheel 16 increases. When the moment of inertia increases, the resonance frequency of the system shifts to the low frequency side. From this, the resonance frequency of the driving system shifts to the low frequency side as the characteristic 1 where the moment of inertia of the flywheel 16 is smallest shifts to characteristics 2 to 4 where the moment of inertia increases.

  Moreover, the vibration allowable value B is shown in the characteristic graph of FIG. The vibration allowable value B indicates the maximum value of the gain that can be allowed by the vehicle occupant. Further, in FIG. 6, a range in which each of the characteristics 1 to 4 exceeds the allowable vibration value B is indicated by an arrow. Hereinafter, a range that exceeds the allowable vibration value B is referred to as a “resonance band”.

  The minimum value and the maximum value (both ends of the resonance band) of the resonance band indicate the rotation speed of the internal combustion engine 20 corresponding to each frequency. For example, the rotational speeds of the internal combustion engine 20 corresponding to the lowest value and the highest value of the resonance band of the characteristic 1 are indicated by “Ne1L” and “Ne1H”, respectively.

  FIG. 7 shows a relationship between the amount of current to the stator coil 32, the rotational speed of the internal combustion engine 20, and the resonance band of the drive system as a graph obtained by replacing FIG. The horizontal axis represents the amount of current to the stator coil 32, and the vertical axis represents the rotational speed of the internal combustion engine 20. The hatched portion indicates the resonance band of the drive system.

  Returning to FIG. 1, the control unit 18 adjusts the viscosity of the viscosity variable fluid 30. For example, the control part 18 may be comprised from the computer provided with arithmetic circuit elements, such as CPU, and may be ECU (electronic control unit) which controls a vehicle.

  The control unit 18 may include a plurality of control means. For example, the control unit 18 may include an internal combustion engine start determination unit 80, an internal combustion engine control unit 82, a flywheel control unit 84, an MG1 control unit 86, and an MG2 control unit 88.

  The internal combustion engine start determination means 80 determines whether the internal combustion engine 20 can be started. For example, the internal combustion engine 20 is started when an acceleration request is given from the driver of the vehicle, or when the storage amount (SOC) of the battery 54 is reduced. In such determination, signals from various devices are transmitted to the internal combustion engine start determination means 80. For example, a signal is sent from a power switch, a P position switch, a shift lever position sensor, an accelerator pedal stroke sensor, or the like. The power switch is a switch for starting a vehicle control system. The P position switch is a switch for setting the driving state of the vehicle to the parking position. The shift lever position sensor is a sensor that detects the position of the shift lever (R position, D position, N position, B position, etc.). The accelerator stroke sensor is a sensor that detects the amount of depression of the accelerator pedal.

  The internal combustion engine control means 82 performs start control of the internal combustion engine 20 when a start request is given from the internal combustion engine start determination means 80. For example, when the rotational speed of the internal combustion engine 20 reaches a predetermined rotational speed, the air-fuel mixture is introduced into the combustion chamber of the internal combustion engine 20 and the air-fuel mixture is combusted to rotate the internal combustion engine 20 independently. Moreover, the drive of the internal combustion engine 20 is controlled even after starting. For example, a torque request is obtained from a signal from an accelerator stroke sensor, and the amount of air-fuel mixture, the ignition timing of the air-fuel mixture, and the like are controlled so that an output corresponding to the torque request is obtained.

  The MG2 control means 88 controls the operating state of the rotating electrical machine MG2. For example, when the SOC of the battery 54 is lowered, the rotating electrical machine MG2 is driven using the electric power generated by the rotating electrical machine MG1. The MG1 control means 86 controls the operating state of the rotating electrical machine MG1. For example, when receiving a start request for the internal combustion engine 20 from the internal combustion engine start determination means 80, the MG1 control means 86 controls the rotating electrical machine MG1 so as to perform cranking for rotationally driving the internal combustion engine 20 in a stopped state.

  The flywheel control means 84 controls the moment of inertia and vibration characteristics of the flywheel 16 by controlling the magnetic field applied to the viscosity variable fluid 30. As shown in FIG. 2, the flywheel control unit 84 may receive the rotation speed of the second wheel 28 from the encoder 76 or may receive the rotation speed of the internal combustion engine 20 from the crank angle sensor 78.

  The internal combustion engine start determination means 80, the internal combustion engine control means 82, the flywheel control means 84, and the MG1 control means 86 cooperate with each other to perform start control of the internal combustion engine 20. 8 and 9 illustrate time charts of the starting period of the internal combustion engine 20. In both figures, in the upper graph, the horizontal axis indicates time, and the vertical axis indicates the rotational speed of the internal combustion engine 20. Moreover, the hatching on the graph indicates the resonance band of the vibration of the drive system. In the middle graph, the horizontal axis indicates time, and the vertical axis indicates the cranking torque of the rotating electrical machine MG1. In the lower graph, the horizontal axis indicates time, and the vertical axis indicates the supply current to the stator coil 32. The start period is a period until the rotational speed of the internal combustion engine 20 is reached from 0 to a rotational speed at which independent operation is possible. The self-supporting rotation speed is, for example, 200 to 600 rpm, although it varies depending on the structure of the internal combustion engine 20 or the like.

  As shown in FIG. 8, when a start request for the internal combustion engine 20 is given from the internal combustion engine start determination means 80, the MG1 control means 86 drives the rotary electric machine MG1 to drive the internal combustion engine 20 to rotate. At that time, the flywheel control means 84 increases the viscosity of the variable viscosity fluid 30 and causes the variable viscosity fluid 30 to absorb vibrations generated in the flywheel 16 and the drive system as the internal combustion engine 20 is rotationally driven. For example, the flywheel control unit 84 increases the viscosity of the viscosity variable fluid 30 in accordance with an increase in the rotational speed of the internal combustion engine 20. Here, “increasing the viscosity according to the increase in the number of rotations” means that the viscosity is gradually increased according to the increase in the number of rotations as described later, and the viscosity is increased when the number of rotations reaches a predetermined value. Both of the modes of switching shall be included.

  The flywheel control unit 84 supplies a current to the stator coil 32 so that the vibration characteristic of the drive system changes from the characteristic 1 to the characteristic 2 or the characteristic 3 described above. In FIG. 8, the amount of current supplied to the stator coil 32 is set to the amount of current I <b> 2 so that the vibration characteristic of the drive system becomes the characteristic 2.

  As described above, in the characteristics 2 and 3, the viscosity variable fluid 30 absorbs the vibration of the drive system, so that the vibration gain is lower than the characteristic 4 indicating the vibration characteristics of the conventional drive system. Along with this, the width of the resonance band becomes narrower than that of the characteristic 4. Therefore, when the internal combustion engine 20 is started, the vibration characteristic of the drive system is set to the characteristic 2 or the characteristic 3, thereby narrowing the width of the resonance band and shortening the time when the riding comfort is deteriorated as compared with the conventional case. It becomes possible.

  In order to make the flywheel 16 have the characteristic 2 or the characteristic 3 and the electric power consumed when the cranking torque is temporarily increased so that the rotational speed of the internal combustion engine passes through the resonance band quickly. When compared with the consumed power, the latter consumes less power. For example, the latter is about 10% of the former. Since the power consumption is reduced, the battery 54 can be prevented from being enlarged.

  When the internal combustion engine 20 reaches a predetermined rotational speed by the rotating electrical machine MG1, the internal combustion engine control means 82 introduces the air-fuel mixture into the combustion chamber of the internal combustion engine 20 and burns the air-fuel mixture (ignition start). And the rotational speed of the internal combustion engine 20 is increased to a rotational speed at which independent operation is possible.

  If the supply current to the stator coil 32 is suddenly switched, the inertia of the flywheel 16 may suddenly change and vibration may occur, so-called torque shock may occur. Therefore, as shown in FIG. 9, when switching the characteristics of the drive system, a gradient may be provided in the current change so that the current amount is gradually changed.

  FIG. 10 shows the control flow of FIGS. 8 and 9. The flywheel control means 84 determines whether or not the rotational speed Ne of the internal combustion engine 20 is equal to or higher than the rotational speed Ne1L corresponding to the lowest frequency of the resonance band of characteristic 1 (S10). When the rotational speed Ne of the internal combustion engine 20 is less than the rotational speed Ne1L, the flywheel control means 84 does not supply current to the stator coil 32 (S12).

When the rotational speed Ne of the internal combustion engine 20 is equal to or higher than the rotational speed Ne1L, the flywheel control means 84 increases the amount of current to the stator coil 32 by ΔI _Coil (S14). When performing control as shown in FIG. 8, ΔI _Coil ≧ I _C2 is satisfied. When performing control as shown in FIG. 9, ΔI _Coil <I _C2 is satisfied.

The flywheel control means 84 determines whether or not the amount of current to the stator coil 32 exceeds I _C2 (S16). If it exceeds, the current amount is set to I _C2 (S18), and the set value is set as the current amount I _Coil to the current stator coil 32 (S20). If not, step S18 is skipped and step S20 is executed.

  As another example of the start control, as shown in FIGS. 11 and 12, the flywheel control means 84 shifts the resonance band of the drive system to the low frequency side as the rotational speed of the internal combustion engine 20 increases. Also good. In other words, the viscosity of the viscosity variable fluid 30 may be increased so that the increase in the rotational speed of the internal combustion engine 20 and the decrease in the resonance band of the drive system pass each other.

FIG. 11 shows control for switching the current supplied to the stator coil 32 from I _C1 (= 0) to I _C3 . In other words, a state in which the vibration characteristic of the drive system is switched from characteristic 1 to characteristic 3 is shown. As shown in FIGS. 6 and 7, the resonance band of characteristic 3 is shifted to the lower frequency side than the resonance band of characteristic 1. Using this characteristic, when the rotational speed of the internal combustion engine 20 reaches the rotational speed Ne1L corresponding to the lowest value of the resonance band of the characteristic 1, the vibration characteristic of the drive system is switched from the characteristic 1 to the characteristic 3. By doing so, it is possible to suppress a period in which the gain of vibration of the drive system is equal to or greater than the allowable vibration value B during the start-up period of the internal combustion engine 20.

  In order to reduce the torque shock, as shown in FIG. 12, when switching the characteristics of the drive system, a gradient may be provided in the current change so that the current amount is gradually increased.

FIG. 13 shows the control flow of FIGS. 11 and 12. Points different from the flow of FIG. 10 are steps S24, S26, and S28. In step S24, when the rotational speed Ne of the internal combustion engine 20 is equal to or higher than the rotational speed Ne1L, the flywheel control means 84 increases the amount of current to the stator coil 32 by ΔI _Coil . In the case of performing control as shown in FIG. 11, ΔI _Coil ≧ I _C3 is set. When performing control as shown in FIG. 12, it is assumed that ΔI _Coil <I _C3 . In step S26, it is determined whether or not the current amount of current exceeds I _C3 . If I _C3 is exceeded, the current amount is maintained at I _C3 in step S28.

In FIGS. 9 and 12, the current amount is gradually increased from the time when the rotational speed of the internal combustion engine 20 reaches the rotational speed Ne1L. However, as shown in FIG. May be started at a rotational speed Ne0 lower than Ne1L. By doing in this way, it becomes possible to shorten the period when the rotation speed of the internal combustion engine 20 passes through the resonance band.

Further, as shown in the characteristic diagram of FIG. 7, by utilizing the fact that the resonance bands of the characteristic 2 and characteristic 3 do not overlap, the number of revolutions of the internal combustion engine 20 is increased by avoiding the passage of the resonance band. You may make it make it. For example, as shown in FIG. 15, when the rotational speed of the internal combustion engine 20 is Ne0, current supply to the stator coil 32 is started and the current I _C2 is reached such that the resonance band of the drive system becomes characteristic 2. At that time, the amount of current is maintained at I _C2 . Further, when the rotational speed of the internal combustion engine 20 reaches between the minimum value Ne2L of the characteristic 2 and the maximum value Ne3H of the characteristic 3, the current amount to the stator coil 32 is switched to I _C3 . By doing so, it is possible to increase the rotational speed of the internal combustion engine 20 so as to avoid the passage of the resonance band.

  In addition, although the drive device 10 (and starter) of the vehicle in the above embodiment is a so-called series / parallel hybrid system, it is not limited to this form. For example, even in a parallel hybrid system in which the power of the internal combustion engine 20 and the power of the rotating electrical machine are cooperated to obtain the driving force of the vehicle, the internal combustion engine 20 drives the generator to generate electric power, and this electric power is used to generate the rotating electrical machine. It may be a series hybrid system that drives the vehicle to obtain the driving force of the vehicle. In the case of the parallel hybrid system, the rotating electrical machine that cooperates with the internal combustion engine 20 is a rotating electrical machine that rotationally drives the internal combustion engine 20 at the start. In the case of the series hybrid system, the generator that generates electric power from the internal combustion engine 20 is a rotating electrical machine that rotationally drives the internal combustion engine 20 at the time of starting. Furthermore, a starter motor (cell motor) used only for starting the internal combustion engine 20 may be used instead of the rotating electrical machine MG1 in the present embodiment.

DESCRIPTION OF SYMBOLS 10 Drive device, 14 Shaft, 15 Power split mechanism, 16 Flywheel, 17 Reduction mechanism, 18 Control part, 19 Drive wheel, 20 Internal combustion engine, 22 Crankshaft, 24 Torsion damper, 26 1st wheel, 28 2nd wheel, 30 Viscosity variable fluid, 31 Bearing, 32 Stator coil, 34 Disk portion of first wheel, 36 Boss portion of first wheel, 38 Seal member, 42 Power transmission plate portion of first wheel, 44 Cylindrical portion of second wheel , 46 Disk part of the second wheel, 48 Groove part of the second wheel, 49 Spacer, 50 Coil, 52 Holding part, 54 Battery, 56 Cylinder block, 61 Step part, 65 Projection part, 76 Encoder, 78 Crank angle sensor, 80 internal combustion engine start determination means, 82 internal combustion engine control means, 84 flywheel Lumpur control means, 86 MG1 control unit, 88 MG2 control unit.

Claims (4)

A rotating electrical machine that rotationally drives the internal combustion engine during a start- up period in which the rotational speed of the internal combustion engine is increased to a rotational speed capable of self-rotating by combustion of the air-fuel mixture ;
Enclosed between the first wheel that rotates integrally with a shaft that transmits the driving force of the internal combustion engine and the rotating electrical machine, the second wheel that can rotate relative to the first wheel, and the first wheel and the second wheel. A flywheel comprising: a variable viscosity fluid;
A controller for adjusting the viscosity of the variable viscosity fluid;
With
The control unit increases the viscosity of the viscosity variable fluid during a start-up period of the internal combustion engine, and causes the viscosity variable fluid to absorb vibration generated in the flywheel due to the rotational drive of the internal combustion engine. A starting device for an internal combustion engine. An internal combustion engine starter according to claim 1,
The starter for an internal combustion engine, wherein the control unit increases the viscosity of the variable viscosity fluid in accordance with an increase in the rotational speed of the internal combustion engine. An internal combustion engine starter according to claim 2,
The starter for an internal combustion engine, wherein the controller does not increase the viscosity of the viscosity variable fluid until the rotational speed of the internal combustion engine reaches a first rotational speed. A rotating electrical machine that rotationally drives the internal combustion engine during a start- up period in which the rotational speed of the internal combustion engine is increased to a rotational speed capable of self-rotating by combustion of the air-fuel mixture ;
Enclosed between the first wheel that rotates integrally with a shaft that transmits the driving force of the internal combustion engine and the rotating electrical machine, the second wheel that can rotate relative to the first wheel, and the first wheel and the second wheel. A flywheel comprising: a variable viscosity fluid;
A controller for adjusting the viscosity of the variable viscosity fluid;
With
The control unit shifts a resonance frequency of a drive system including the internal combustion engine and a flywheel to a low frequency side by increasing the viscosity of the viscosity variable fluid during a start period of the internal combustion engine. A starter for an internal combustion engine.

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