JP2014105790A - Vibration suppressing device, and method for internal combustion engine - Google Patents

Abstract

The present invention relates to flywheel control capable of changing the vibration characteristics of an output shaft of an internal combustion engine, to control the flywheel in conformity with the operating state of the internal combustion engine, and to reduce vibration and noise.
A flywheel is interposed between a first wheel that rotates integrally with an output shaft of an internal combustion engine, a second wheel that can rotate relative to the first wheel, and a first wheel and a second wheel. A magnetorheological fluid; and an electromagnet that forms a magnetic field acting on the magnetorheological fluid. In the operating state of the internal combustion engine, the current I5 is supplied to the electromagnet when the rotational speed is low and the output torque is large, and no current is supplied to the electromagnet when the rotational speed is high and the output torque is small (current I1). It is also possible to provide a transition range between these two ranges so that the current changes stepwise (I2, I3, I4). Thereby, the rotation fluctuation | variation which causes a vibration and noise is suppressed.
[Selection] Figure 8

Description

  The present invention relates to suppression of vibration caused by rotational fluctuations of an internal combustion engine.

  In an internal combustion engine, particularly an Otto engine or a diesel engine that performs intermittent combustion, fluctuations in rotational speed (hereinafter referred to as rotational fluctuations) due to intermittent combustion occur. This rotational fluctuation is transmitted from an internal combustion engine and a power transmission system that transmits the power of the internal combustion engine to a frame that supports them, and may generate vibration and noise. In an internal combustion engine equipped with a vehicle, vibration is transmitted to the vehicle body from a mount that supports a power transmission system such as the internal combustion engine, a transmission that transmits power of the internal combustion engine, a propeller shaft, a drive shaft, and a final reduction gear. , Noise is generated.

  In order to suppress rotational fluctuations caused by intermittent combustion, a flywheel is generally provided on the output shaft of the internal combustion engine. The greater the moment of inertia of the flywheel, the greater the effect of suppressing rotational fluctuations. On the other hand, the response speed, that is, the response speed related to increase / decrease in the rotation speed is lowered.

  In Patent Document 1 listed below, a flywheel that can be switched between high and low binary moments of inertia has a high moment of inertia at low revolutions and a low moment of inertia at high revolutions, thereby suppressing vibration and noise and high responsiveness. (See, for example, the second page, upper left column, lines 5-10).

JP-A-1-266336

  The rotational fluctuation of the internal combustion engine is influenced not only by the rotational speed but also by the output torque. In general, the rotational fluctuation becomes larger when the output torque is higher. Therefore, there are cases where the rotational fluctuation cannot be suppressed only by switching the moment of inertia based on the rotational speed. Further, if the value of the moment of inertia that can be taken is only a binary value, it may be impossible to achieve both the suppression of rotational fluctuation and the demand for high responsiveness.

  An object of the present invention is to suppress rotational fluctuation more effectively in a wider operating range of an internal combustion engine and to achieve at least one of suppression of rotational fluctuation and high responsiveness.

  The vibration suppression device for an internal combustion engine of the present invention suppresses vibration by changing the characteristics of the vibration system formed by the internal combustion engine and the power transmission system by a flywheel capable of changing the vibration characteristics. The flywheel includes a first wheel that rotates integrally with an output shaft of the internal combustion engine, a second wheel that can rotate relative to the first wheel, a variable viscosity fluid that is interposed between the first wheel and the second wheel, and a viscosity. A viscosity adjusting unit for adjusting the viscosity of the variable fluid; Furthermore, the vibration suppressing device has a control unit that operates the viscosity adjusting unit to control the viscosity of the variable viscosity fluid. The characteristics of the vibration system can be changed by controlling the viscosity of the variable viscosity fluid of the flywheel. For example, the second wheel can be separated from the vibration system by reducing the viscosity of the variable viscosity fluid, while the second wheel is integrated with the first wheel by increasing the viscosity, and the second wheel is integrated with the vibration system. Can be incorporated into.

  The flywheel is controlled based on the rotational speed and output torque of the internal combustion engine. A rotation speed acquisition unit is provided for acquiring the rotation speed of the internal combustion engine, and a torque acquisition unit is provided for acquiring the output torque of the internal combustion engine. The operating state of the internal combustion engine is determined by the set of the acquired rotation speed and output torque. In this operating state, a vibration suppression range that is a range in which vibration caused by the internal combustion engine is to be suppressed is determined in advance. When the acquired rotation speed and output torque are within the vibration suppression range, the control unit performs control to increase the viscosity of the variable viscosity fluid as compared with a case outside the vibration suppression range.

  A transition range can be set adjacent to the vibration suppression range. When the operating state of the internal combustion engine is in the transition range, the control unit can control the viscosity of the variable viscosity fluid to increase stepwise or gradually as the operating state is closer to the vibration suppression range. it can.

  The variable viscosity fluid may be a fluid whose viscosity changes in response to a magnetic field. Examples of such fluid include a magnetorheological fluid (MR fluid) and a magnetic fluid. By adjusting the magnetic field acting on these fluids, the viscosity can be controlled. The magnet can be an electromagnet, for example, and the magnetic field acting on the magnetorheological fluid or the like can be adjusted by controlling the current supplied by the electromagnet.

  By controlling the flywheel based on the operating state determined as a set of the rotational speed and output torque of the internal combustion engine, it is possible to more effectively reduce rotational fluctuations and suppress vibration caused by the internal combustion engine.

It is a figure which shows schematic structure of the internal combustion engine and power transmission system which are mounted in the vehicle. It is a figure which shows the detailed structure of a flywheel. It is a figure which shows the magnetic field which acts on a flywheel. It is a figure which shows the relationship between the electric current supplied to the electromagnet which forms a magnetic field, and the viscosity of a magnetorheological fluid. It is a figure which shows the change of the vibration characteristic of a power transmission system when the viscosity of a magnetorheological fluid is changed. It is explanatory drawing regarding the driving | running state of an internal combustion engine, and vibration suppression control. It is another explanatory drawing regarding the driving | running state of an internal combustion engine, and vibration suppression control. It is explanatory drawing regarding control of a flywheel.

  Hereinafter, an internal combustion engine vibration suppression device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine 10 and a power transmission device 12 mounted on a vehicle as an example of an internal combustion engine and a power transmission system that transmits power of the internal combustion engine. FIG. 1 shows a layout of a so-called FR vehicle in which an internal combustion engine is mounted in the front part of the vehicle and the rear wheels are used as drive wheels. In FIG. 1, each component is schematically represented, and the size and shape thereof do not necessarily match those of the actual one.

  The internal combustion engine 10 is a four-cylinder reciprocating piston engine such as an Otto engine or a diesel engine, but may be another heat cycle engine that performs intermittent combustion. Also, the number of cylinders may be another number of cylinders. The power transmission device 12 includes a flywheel 16 coupled to the output shaft 14 of the internal combustion engine, a transmission 18 that converts the rotational speed of the output of the internal combustion engine and sends it to drive wheels, a propulsion shaft 20, and a final reduction gear 22. And a drive shaft 24 and a drive wheel 26. The transmission 18 may be a multi-stage manual transmission, a multi-stage automatic transmission, or a continuously variable transmission. The final reduction gear 22 further decelerates the output transmitted from the transmission 18 via the propulsion shaft 20 and distributes it to the left and right drive wheels 26 by a differential mechanism. The drive shaft 24 connects the final reduction gear 22 and the drive wheel 26. The transmission 18 and the final reduction gear 22 may be integrated as is often seen in vehicles with an FF layout. In this case, the propulsion shaft 20 is omitted.

  The flywheel 16 includes a first wheel 28 that rotates integrally with the output shaft 14, and a second wheel 30 that is disposed so as to be rotatable relative to the first wheel 28, with the axis of the output shaft 14 as a rotation axis. Between the first wheel 28 and the second wheel 30, a variable viscosity fluid 32 capable of changing the viscosity is interposed. The flywheel 16 has a viscosity adjusting unit 34 for adjusting the viscosity of the variable viscosity fluid. The configuration of the viscosity adjusting unit 34 is determined according to the property of the viscosity variable fluid 32. A magnetorheological fluid or a magnetorheological fluid can be employed as the variable viscosity fluid 32, and the corresponding viscosity adjusting unit 34 includes a magnet. A magnetorheological fluid or the like has a property that the viscosity is changed by an applied magnetic field, and the viscosity can be controlled by adjusting the magnetic force of the magnet. In order to adjust the magnetic force, an electromagnet can be used as the magnet. By controlling the current supplied to the electromagnet, the magnetic field acting on the magnetorheological fluid can be adjusted. The magnet can be a permanent magnet. In this case, for example, the magnetic field acting on the magnetorheological fluid can be changed by changing the position of the permanent magnet.

  The magnetorheological fluid can be, for example, a magnetic colloidal solution composed of ferromagnetic fine particles such as magnetite and manganese zinc ferrite, a surfactant covering the surface, and a base liquid such as oil. Moreover, the fluid (electrorheological fluid) which changes a viscosity by making an electric field act can be used as a viscosity variable fluid. In this case, the electric field acting on the fluid can be adjusted by providing an electrode and controlling the voltage applied to the electrode.

  The vibration suppressing device further includes a flywheel control unit 36 that controls the vibration characteristics of the flywheel 16 by adjusting the viscosity of the variable viscosity fluid 32. The flywheel control unit 36 determines the operating state of the internal combustion engine from the rotational speed and output torque of the internal combustion engine, and controls the flywheel 16 according to the operating state. The internal combustion engine 10 is controlled by the internal combustion engine control unit 38.

  Hereinafter, a flywheel using a magnetorheological fluid as the viscosity variable fluid 32 will be described as an example. The symbol 32 is also used as a symbol indicating the magnetorheological fluid.

  FIG. 2 is a diagram showing details of the flywheel 16 and its surroundings. The first wheel 28 includes a base portion 40 coupled to the output shaft 14 and a disk-shaped disc portion 42 coupled to the base portion 40. The base portion 40 has a substantially cylindrical shape, and is coupled to a flange 44 of the output shaft (crankshaft) 14 of the internal combustion engine 10 by a fastening member (not shown) such as a bolt. A spline (female) is formed on the cylindrical inner peripheral surface of the base portion 40 and engages with a spline (male) provided on an input shaft (not shown) of the transmission 18 so that the power of the internal combustion engine 10 is transmitted to the transmission 18. Is transmitted to. An annular plate-shaped rotation transmission plate 48 is provided on the outer circumference of the base 40. The rotation transmission plate 48 will be described again later. The disc portion 42 is coupled to the cylindrical end surface of the base portion 40 by a fastening member such as a bolt (not shown). This bolt can also be used as a bolt for fastening the flange 44 and the base 40 of the output shaft. Moreover, you may make it the base 40 and the disc part 42 couple | bond together permanently by welding etc. FIG. An annular weight 50 that is thicker than the inner part is provided on the outer periphery of the disc plate 42.

  The second wheel 30 includes a substantially cylindrical base portion 52 and an annular plate portion 54 having an annular plate shape. The base 40 of the first wheel and the base 52 of the second wheel are coaxially arranged with the rotation axis Ax of the output shaft 14 as a common central axis. Further, a bearing 56 is interposed between these base portions 40 and 42, whereby the second wheel 30 is rotatably supported by the first wheel 28. The bearing 56 can be a rolling bearing such as a ball bearing or a roller bearing. A groove 58 extending in the circumferential direction over the entire circumference is formed on the inner circumferential surface of the base 52. In this groove 58, the rotation transmission plate 48 of the base 40 of the first wheel enters. The base 52 has three annular parts arranged in the direction of the rotation axis Ax, and these parts sandwich the magnetic flux blocking part 60 made of a non-magnetic material at the center and the magnetic flux blocking part 60. The first yoke portion 62 and the second yoke portion 64 are provided as described above. The magnetic flux shielding part 60 is located outside the groove 58. In this embodiment, the magnetic flux shielding part 60 and the groove 58 have the same size in the direction of the rotation axis Ax, but the present invention is not limited thereto. An annular weight portion 66 that is thicker than the inner portion is provided on the outer peripheral portion of the annular plate portion 54. The annular plate portion 54 can be formed integrally with the base portion 52, particularly the second yoke portion 64. The magnetic flux blocking section 60 only needs to be configured such that the magnetic flux is less likely to be transmitted through the first and second yoke sections 62 and 64. May be lowered.

  Sealing rings 67 are provided on both sides of the groove 58 and the rotation transmission plate 48 in the direction of the rotation axis Ax to seal between the outer peripheral surface of the base portion 40 of the first wheel and the inner peripheral surface of the base portion 52 of the second wheel. It has stopped. As a result, the space inside the groove 58 is closed from the outside. In this space, the magnetorheological fluid 32 is enclosed. Thereby, the wall surface and the bottom surface of the groove 58 and the end surface and the side surface of the rotation transmission plate 48 are opposed to each other with the magnetic viscous fluid 32 therebetween.

  The viscosity adjusting unit 34 includes an electromagnet 72 having a coil 68 and a yoke 70. The electromagnet 72 is supported by a support portion 76 fixed to the cylinder block 74 of the internal combustion engine 10. The electromagnet 72 is disposed so as to face the outer peripheral surface of the base 52 of the second wheel 30. The electromagnet coil 68 is arranged so as to go around the outside of the base portion 52, and the yoke 70 is arranged so as to correspond to the first and second yoke portions 62 and 64 of the second wheel base portion. Electric power is supplied from the battery 78 to the electromagnet 72 based on a command from the control unit 36 to generate a magnetic field. The flywheel control unit 36 controls the viscosity of the magnetorheological fluid 32 by controlling the current supplied to the electromagnet 72.

  This control is executed based on the rotational speed and output torque of the internal combustion engine. The rotational speed of the internal combustion engine can be acquired based on an output signal of a rotational speed sensor 80 provided in the vicinity of a rotating body (for example, the output shaft 14) such as a shaft that rotates with a fixed relationship with the output shaft of the internal combustion engine 10. . The flywheel control unit 36 may calculate the rotation speed of the internal combustion engine based on the signal from the rotation speed sensor 80, and the rotation calculated based on the signal from the rotation speed sensor 80 by the internal combustion engine control unit 38. The speed may be acquired. In the former case, the flywheel control unit 36 functions as a rotational speed acquisition unit that acquires the rotational speed of the internal combustion engine together with the rotational speed sensor 80. In the latter case, the rotation speed sensor 80, the internal combustion engine control unit 38, and the flywheel control unit 36 function as a rotation speed acquisition unit.

  The output torque of the internal combustion engine can be acquired from the internal combustion engine control unit 38. The internal combustion engine control unit 38 obtains an output to be generated by the internal combustion engine 10 based on a request relating to the output of the internal combustion engine 10, and controls each part (throttle valve, fuel injection valve, etc.) of the internal combustion engine 10 based on this. . That is, the internal combustion engine control unit 38 has information regarding the output torque, and the flywheel control unit 36 acquires this and controls the flywheel 16. The flywheel control unit 36 functions as an output torque acquisition unit that acquires the output torque of the internal combustion engine together with the internal combustion engine control unit 38. The output torque may be acquired based on a signal from a torque sensor provided on the output shaft of the internal combustion engine. In this case, the torque sensor and the flywheel control unit function as an output torque acquisition unit.

  FIG. 3 is a diagram showing a magnetic field generated by the electromagnet 72, and magnetic flux lines are indicated by a broken line M. The magnetic flux extends from one end (left end in the figure) of the yoke 70 of the electromagnet to the first yoke portion 62 of the second wheel base and travels to the second yoke portion 64 so as to cross the groove 58. The magnetic flux blocking portion 60 provided between the first yoke portion 62 and the second yoke portion 64 prevents or suppresses the magnetic flux from bypassing the groove 58. The magnetic flux returns to the other end (right end in the figure) of the yoke 70 of the electromagnet directly from the first yoke portion or via the annular plate portion 54 of the second wheel. The magnetic flux traversing the groove 58 acts on the magnetorheological fluid 32 in the groove 58 and changes the viscosity of the magnetorheological fluid 32. The rotation transmission plate 48 enters the groove 58, and the transmission characteristic from the rotation transmission plate 48 to the base 52 of the second wheel changes as the viscosity of the magnetorheological fluid 32 changes. When the electromagnet 72 does not generate a magnetic field, the viscosity of the magnetorheological fluid 32 is the lowest, and even if there is a relative rotational fluctuation between the rotation transmission plate 48 and the base 52 of the second wheel, the second wheel 30. Is hardly transmitted. When the magnetic field becomes stronger, the viscosity of the magnetorheological fluid 32 becomes higher, and the second wheel 30 is dragged by the rotation transmission plate 48 via the magnetorheological fluid 32 and the rotation fluctuates. When the magnetic field is further increased, the magnetorheological fluid 32 couples the rotation transmission plate 48 and the second wheel 30 together.

  FIG. 4 is a diagram showing the relationship between the current supplied to the electromagnet 72 and the viscosity of the magnetorheological fluid 32. When the current I is 0 (I = I1 = 0), the viscosity is the lowest, and as the current I increases, the viscosity increases almost proportionally. When the current is 0, the rotation is hardly transmitted to the second wheel 30, and when the current is I5, the second wheel 30 rotates integrally with the first wheel 28.

  FIG. 5 is a diagram showing the vibration characteristics of the power transmission system in which the horizontal axis represents the rotational speed (frequency) of the internal combustion engine and the vertical axis represents the gain. Characteristics C1 to C5 corresponding to the currents I1 to I5 shown in FIG. 4 are shown. The characteristic C1 is a characteristic when no current is supplied to the electromagnet 72 (I1), the characteristic C2 is the current I2, the characteristic C3 is the current I3, the characteristic C4 is the current I4, and the characteristic C5 is the current I5. The characteristics are shown. The characteristic C1 is a characteristic substantially determined by the first wheel 28, and the second wheel 30 is not involved in the vibration system. The characteristic C5 is a vibration system in which the first and second wheels 28 and 30 are integrated, and is not affected by the viscosity of the magnetorheological fluid 32. The characteristics C2 to C4 are characteristics influenced by the viscosity of the magnetorheological fluid 32, and the peaks are lower than those of the characteristics C1 and C5.

  FIG. 6 is a diagram illustrating the relationship between the operating state of the internal combustion engine and the control of the flywheel 16. The operating state of the internal combustion engine is expressed as a set of the rotational speed and output torque of the internal combustion engine. In the figure, the operating state is expressed as coordinates on a coordinate plane with the rotational speed as the horizontal axis and the output torque as the vertical axis. The range A5 shown is an area where the rotational speed is low and the output torque is high, and vibration / noise is a problem. On the other hand, the range A1 has a high rotational speed and a low output torque. For this reason, the problem of vibration and noise hardly occurs. As can be understood from the figure, whether or not vibration / noise becomes a problem depends on the difference in rotational speed even with the same output torque. Similarly, whether or not vibration / noise becomes a problem depends on the difference in output torque even at the same rotational speed. Therefore, it is possible to grasp the operation state in more detail than to grasp the operation state based on only the rotation speed or only the output torque.

  In the range A1 shown, no current is supplied to the electromagnet 72 of the flywheel 16. Thereby, the 2nd wheel 30 will be in the state isolate | separated from the vibration system, and the inertia moment of the flywheel 16 will become small. By reducing the moment of inertia, the responsiveness of the rotational speed of the internal combustion engine can be maintained high. On the other hand, since the range A1 is a region where the problem of vibration and noise does not appear as described above, no problem regarding vibration and noise occurs even if the inertia moment of the flywheel 16 is small. In the range A5, the current I5 is supplied to the electromagnet 72 and the first and second wheels 28 and 30 are controlled to be integrated. The range A5 is a region where vibration and noise are a problem, and by adding the moment of inertia of the second wheel 30, the rotational fluctuation of the internal combustion engine is suppressed.

  FIG. 7 is a diagram showing another example of the relationship between the operating state of the internal combustion engine and the control of the flywheel 16. In FIG. 7 as well, as in FIG. 6, the operating state is expressed using coordinates based on the rotational speed and output torque. The range B1 in FIG. 7 is the same range as the range A1 in FIG. The range A5 in FIG. 6 is divided into four ranges B2 to B5 in FIG.

  In the range B1, no current is supplied to the electromagnet 72 of the flywheel 16. Thereby, the 2nd wheel 30 will be in the state isolate | separated from the vibration system, and the inertia moment of the flywheel 16 will become small. By reducing the moment of inertia, the responsiveness of the rotational speed of the internal combustion engine can be maintained high. On the other hand, since the range B1 is a region where the problem of vibration and noise does not appear as described above, no problem regarding vibration and noise occurs even if the inertia moment of the flywheel 16 is small. In the range B5, the current I5 is supplied to the electromagnet 72, and the first and second wheels 28 and 30 are controlled to be integrated. The range B5 is a region where vibration and noise are a problem, and by adding the moment of inertia of the second wheel 30, fluctuations in the rotation of the internal combustion engine are suppressed.

  A transition range in which the current I changes from the current I5 to the current I1 is set between the range B5 and the range B1. In this example, the transition range is divided into three ranges B2, B3, B4, and currents I2, I3, I4 are supplied to the electromagnet 72 in each range. The transition range may be a range other than three, or the current value may change continuously. Since the transition range is a region where the problem of vibration and noise is less problematic than in the case of the range B5, the second wheel 30 is controlled not to be completely integrated with the first wheel in consideration of responsiveness.

  FIG. 8 is a diagram showing the rotational speed of the internal combustion engine when the output torque is fixed and the fluctuations in the rotational speed. The horizontal axis represents the rotation speed, and the vertical axis represents the rotation fluctuation (amplitude). Further, symbol Th shown in the figure is an allowable limit value of rotational fluctuation, and if this value is exceeded, vibration and noise are detected, which causes a problem. The characteristics indicated by reference numerals D1 to D5 indicate rotational fluctuations when currents I1 to I5 are supplied to the electromagnet 72 of the flywheel, respectively.

  As shown in FIG. 6, when two ranges A1 and A5 are set for the operating state of the internal combustion engine, the current I5 is supplied in the low speed range, and this is maintained until the rotational speed N1 where the characteristic D1 falls below the allowable limit value Th. Is done. Thereafter, the current I1 is supplied. In the setting having the transition range as shown in FIG. 7, the current I5 is supplied in the low rotation range, and this is maintained until the rotation speed N2 where the characteristic D4 is below the allowable limit value Th. When the rotational speed N2 is exceeded, the current I4 is supplied and maintained until the rotational speed at which the characteristic D3 falls below the allowable limit value Th. This is repeated. In the transition range, the viscosity of the magnetorheological fluid 32 is finely controlled. Thereby, in the transition range, vibration and noise are suppressed, and the responsiveness of the internal combustion engine is ensured to some extent.

  In the above embodiment, the second wheel 30 is supported by the first wheel 28 integrated with the output shaft, but may be directly supported by the output shaft or the shaft integrated therewith. it can. Further, the present invention relates to a vehicle that travels with the driving force of only the internal combustion engine described above, but it can also be applied to a hybrid vehicle in which another prime mover such as an electric motor is combined.

  DESCRIPTION OF SYMBOLS 10 Internal combustion engine, 12 Power transmission device, 14 Output shaft, 16 Flywheel, 28 1st wheel, 30 2nd wheel, 32 Magnetorheological fluid (viscosity variable fluid), 34 Electromagnet (viscosity adjustment part), 36 Flywheel control part , 38 Internal combustion engine control unit, 40 (first wheel) base, 48 rotation transmission plate, 52 (second wheel) base, 58 groove, 72 electromagnet, 80 rotational speed sensor.

Claims (5)

A first wheel that rotates integrally with the output shaft of the internal combustion engine, a second wheel that can rotate relative to the first wheel, a variable viscosity fluid that is interposed between the first wheel and the second wheel, and a viscosity of the variable viscosity fluid A flywheel having a viscosity adjusting unit to be adjusted;
A control unit for operating the viscosity adjusting unit to control the viscosity of the variable viscosity fluid;
A rotation speed acquisition unit for acquiring the rotation speed of the internal combustion engine;
A torque acquisition unit for acquiring the output torque of the internal combustion engine;
Have
When the acquired rotational speed and output torque of the internal combustion engine are within a predetermined vibration suppression range in an operating state determined as a set of the rotational speed and output torque of the internal combustion engine, the control unit To suppress the vibration caused by the internal combustion engine,
A vibration suppression device for an internal combustion engine. The vibration suppression device for an internal combustion engine according to claim 1,
In the predetermined transition range adjacent to the vibration suppression range, the control unit gradually increases the operating state of the internal combustion engine corresponding to the acquired rotation speed and output torque of the internal combustion engine closer to the vibration suppression range. Or control so that the viscosity of the viscosity variable fluid gradually increases,
A vibration suppression device for an internal combustion engine. The vibration suppression device for an internal combustion engine according to claim 1 or 2,
The viscosity variable fluid is a fluid whose viscosity changes by a magnetic field,
The viscosity adjusting unit is a magnet that generates a magnetic field acting on the fluid,
The control unit controls a viscosity of the fluid by changing a magnetic field acting on the fluid of the magnet.
A vibration suppression device for an internal combustion engine. A first wheel that rotates integrally with the output shaft of the internal combustion engine, a second wheel that can rotate relative to the first wheel, a variable viscosity fluid that is interposed between the first wheel and the second wheel, and a viscosity of the variable viscosity fluid Attaching a flywheel having a viscosity adjusting unit for adjusting the output shaft of the internal combustion engine;
Storing a vibration suppression range in an operating state determined as a set of the rotational speed and output torque of the internal combustion engine;
Acquiring the rotational speed and output torque of the internal combustion engine and grasping the operating state of the internal combustion engine;
When the grasped operating state is within the vibration suppression range, the step of operating the viscosity adjusting unit to increase the viscosity of the variable viscosity fluid;
A vibration suppression method for an internal combustion engine, comprising: A method for suppressing vibrations of an internal combustion engine according to claim 4,
Storing a transition range adjacent to the vibration suppression range;
When the grasped operation state is in the transition range, the step of controlling the viscosity of the combustible fluid to increase gradually or gradually as the grasped operation state is closer to the vibration suppression range; and
A vibration suppression method for an internal combustion engine, comprising:

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