Roll vibration reduction device for internal combustion engine

Abstract

The present invention provides a roll vibration reduction device for an internal combustion engine capable of reducing the roll vibration of the internal combustion engine. The roll vibration reduction device for an internal combustion engine includes: a main inertia system configured to rotate integrally with a crankshaft of the internal combustion engine; a drive force transmission mechanism configured to transmit the rotational drive force of the crankshaft in a manner that reverses the direction of rotation; and a secondary inertia system configured to rotate using the rotational drive force transmitted from the drive force transmission mechanism and configured to reduce the roll vibration of the internal combustion engine associated with the rotation of the crankshaft by rotating in a direction opposite to the rotational direction of the crankshaft. The torsional resonance frequency in the roll vibration reduction device is set to be higher than the first-order explosion frequency at the highest speed within a predetermined operating range of the internal combustion engine.

Description

Technical Field

[0001] The present disclosure relates to a roll vibration reducing apparatus for an internal combustion engine. Background Art

[0002] Japanese Patent Application Laid-Open No. 6-042591 discloses a technology in which, in a roll vibration reduction device that utilizes the reverse rotation of a secondary inertia system to offset the roll vibration of an internal combustion engine body generated by the rotation of the crankshaft of the internal combustion engine, when resonance occurs and the roll vibration cannot be offset, the roll vibration reduction device is cut off without performing useless rotation.

[0003] However, in the technique disclosed in Japanese Patent Application Laid-Open No. 6-042591, the roll vibration reducing device is cut off when resonance occurs, and therefore the roll vibration reducing effect cannot be obtained. Summary of the Invention

[0004] The present disclosure provides a roll vibration reducing apparatus for an internal combustion engine capable of reducing the roll vibration of the internal combustion engine.

[0005] A roll vibration reduction device for an internal combustion engine according to one embodiment of the present disclosure includes: a primary inertia system configured to rotate integrally with a crankshaft of the internal combustion engine; a drive force transmission mechanism configured to transmit the rotational drive force of the crankshaft in a manner that reverses the direction of rotation; and a secondary inertia system configured to rotate using the rotational drive force transmitted from the drive force transmission mechanism and configured to reduce roll vibration of the internal combustion engine associated with the rotation of the crankshaft by rotating in a direction opposite to the rotational direction of the crankshaft. The torsional resonance frequency of the roll vibration reduction device is set to be higher than the first-order explosion frequency at the highest speed within a predetermined operating range of the internal combustion engine.

[0006] According to the roll vibration reducing apparatus of an internal combustion engine according to one embodiment of the present disclosure, the internal combustion engine is operated without exceeding the torsional resonance frequency, and thus the roll vibration of the internal combustion engine can be reliably reduced.

[0007] In the roll vibration reducing apparatus of an internal combustion engine according to one embodiment of the present disclosure, the inertia moment of at least one of the primary inertial system and the secondary inertial system may be set so that the torsional resonance frequency is higher than the explosion first-order frequency.

[0008] According to the roll vibration reducing apparatus of an internal combustion engine according to one embodiment of the present disclosure, it is possible to change the inertia moment of at least one of the primary inertia system and the secondary inertia system to increase the torsional resonance frequency.

[0009] In the roll vibration reducing apparatus of an internal combustion engine according to one aspect of the present disclosure, the torsional rigidity of the torsional rigidity element in the roll vibration reducing apparatus may be set so that the torsional resonance frequency is set higher than the explosion first-order frequency.

[0010] According to the roll vibration reducing apparatus of an internal combustion engine according to one embodiment of the present disclosure, it is possible to change the torsional rigidity of the torsional rigid element and increase the torsional resonance frequency.

[0011] The roll vibration reducing device of an internal combustion engine disclosed in the present disclosure has the effect of reliably reducing the roll vibration of the internal combustion engine because the internal combustion engine is operated without exceeding the torsional resonance frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like parts, and in which:

[0013] Figure 1 It is a diagram showing an example of a roll vibration reducing device according to an embodiment.

[0014] Figure 2 This is a diagram showing the relationship between the torsional resonance frequency and the explosion first-order frequency in the roll vibration reduction apparatus according to the embodiment.

[0015] Figure 3 The diagram shows waveforms of engine torque, MG torque+gear reaction force, and power plant input torque in the engine operating range when the explosion first-order frequency at the engine maximum speed in the engine operating range is lower than the torsional resonance frequency.

[0016] Figure 4 The graph shows waveforms of engine torque, MG torque+gear reaction force, and power plant input torque when the explosion first-order frequency at the maximum engine speed in the engine operating range is equal to or higher than the torsional resonance frequency.

[0017] Figure 5 Graph showing the transmission gain and phase of the torque transmitted to the secondary inertial system relative to the torque of the primary inertial system.

[0018] Figure 6 This is a graph showing the roll torque when the engine is operated by sweeping the engine speed from 1100 [rpm] to 5000 [rpm].

[0019] Figure 7 It will Figure 6 The figure is an enlarged view of the engine speed near 1100 [rpm].

[0020] Figure 8 It will Figure 6 The figure is an enlarged view of the engine speed near 5000 [rpm].

[0021] Figure 9 This is a diagram showing a case where the torsional resonance frequency is set to be twice or more the explosion first-order frequency in the roll vibration reducing apparatus according to the embodiment.

[0022] Figure 10 This is a diagram showing a torque waveform including an explosive second-order component.

[0023] Figure 11 This is a diagram showing an example of a roll vibration reducing device according to Modification 1.

[0024] Figure 12 This is a diagram showing an example of a roll vibration reducing device according to a second modification.

[0025] Figure 13 This is a diagram showing an example of a roll vibration reducing device according to a third modification. DETAILED DESCRIPTION

[0026] The following describes an embodiment of the roll vibration reduction device for an internal combustion engine disclosed in the present invention (hereinafter also simply referred to as the roll vibration reduction device). In addition, the applicable embodiments are not limited by this embodiment. The roll vibration reduction device for an internal combustion engine disclosed in the present invention is mounted on an electric vehicle such as a series hybrid vehicle, and comprises: a main inertia system that rotates integrally with the crankshaft of the internal combustion engine; a driving force transmission mechanism that transmits the rotational driving force of the crankshaft in a manner that reverses the direction of rotation; and a secondary inertia system that rotates using the rotational driving force transmitted from the driving force transmission mechanism. The roll vibration reduction device for an internal combustion engine is configured to reduce the roll vibration of the internal combustion engine accompanying the rotation of the crankshaft by rotating the secondary inertia system in a direction opposite to the rotation direction of the crankshaft.

[0027] Figure 1 This figure shows an example of a roll vibration reduction device according to an embodiment. The roll vibration reduction device according to the embodiment includes an engine 1 as an internal combustion engine included in a primary inertial system, a motor generator 2 included in a secondary inertial system, and a driving force transmission mechanism 3 that transmits rotational driving force from engine 1 to motor generator 2. In this embodiment, engine 1 is a three-cylinder, four-stroke engine.

[0028] The motor generator 2 is a rotating electrical machine having a rotor 21, a stator 22, and a rotor shaft 23. It functions as, for example, a three-phase AC electric motor and a generator. The rotor 21 is rotatably disposed coaxially inside the stator 22. A rotor shaft 23 is coaxially disposed within the rotor 21, and the rotor 21 and rotor shaft 23 rotate integrally.

[0029] The driving force transmission mechanism 3 includes a gear train consisting of a drive gear 31 and a driven gear 32 that mesh with each other. The rotational driving force input to the drive gear 31 is output from the driven gear 32 in a manner that reverses the direction of rotation. The drive gear 31 is coaxially mounted on the crankshaft 11 of the engine 1, and the crankshaft 11 rotates integrally with the drive gear 31. The driven gear 32 is coaxially mounted on the rotor shaft 23 of the motor generator 2, and the rotor shaft 23 rotates integrally with the driven gear 32. Parallel gears, helical gears, or the like can be used as the drive gear 31 and the driven gear 32.

[0030] In the roll vibration reduction device of the embodiment, the rotational drive force of the crankshaft 11 of the engine 1 is reversed and transmitted to the rotor shaft 23 via the drive gear 31 and driven gear 32 of the drive force transmission mechanism 3, causing the rotor 21 of the motor generator 2 to rotate in the direction opposite to the rotation direction of the crankshaft 11. In order to reduce the roll vibration of the engine 1 associated with the rotation of the crankshaft 11, the rotor 21 of the motor generator 2 functions as a Heron balancer that rotates in the direction opposite to the rotation direction of the crankshaft 11.

[0031] In this embodiment, the engine 1, the motor generator 2, and the driving force transmission mechanism 3 constitute a power unit (power generation unit), and the driving force transmission mechanism 3 can transmit the rotational driving force from the engine 1 to the motor generator 2 to generate electricity. The electric power generated by the motor generator 2 is charged into a battery or the like as a power storage device, for example, via an inverter or the like.

[0032] Figure 2 Graphs showing the first-order explosion frequency and the torsional resonance frequency of the engine 1 in the roll vibration reducing apparatus according to the embodiment. Figure 3 The diagram shows waveforms of engine torque, MG torque+gear reaction force, and power plant input torque in the engine operating range when the explosion first-order frequency at the engine maximum speed in the engine operating range is lower than the torsional resonance frequency. Figure 4 This diagram shows waveforms of engine torque, MG torque+gear reaction force, and power plant input torque when the first-order explosion frequency at the maximum engine speed in the engine operating range is equal to or higher than the torsional resonance frequency.

[0033] In addition, in this embodiment, the torque that rotates the crankshaft 11 in the engine 1 is referred to as the engine torque, the torque that rotates the rotor 21 of the motor generator 2 is referred to as the MG torque, and the reaction force of the driven gear 32 relative to the rotation of the drive gear 31 of the driving force transmission mechanism 3 is referred to as the gear reaction force.

[0034] like Figure 2 As shown, in the roll vibration reduction device of the embodiment, the torsional resonance frequency (the resonance frequency formed by the torsional stiffness of the primary inertial system, the secondary inertial system, and the torsional stiffness between the primary inertial system and the secondary inertial system) in the roll vibration reduction device is set higher than the first-order explosion frequency at the maximum engine speed in the engine operating range. Figure 3 As shown, in the entire engine operating range, the MG torque + gear reaction force has the same magnitude as the engine torque and is in the opposite direction and the same phase (timing). As a result, the roll vibration reduction effect can be obtained in the entire engine operating range.

[0035] On the other hand, when the engine 1 is operated so that the first-order explosion frequency at the highest engine speed in the engine operating range becomes equal to or higher than the torsional resonance frequency in the roll vibration reduction device, as shown in FIG. Figure 4 As shown, the phases of the engine torque and the MG torque + gear reaction force may be misaligned, which may amplify the roll vibration and worsen the roll vibration.

[0036] In the roll vibration reduction device of the embodiment, by changing at least one of the moment of inertia and torsional stiffness of the primary or secondary inertial system, thereby reducing the moment of inertia or increasing the torsional stiffness, the torsional resonance frequency of the roll vibration reduction device can be increased, and the torsional resonance frequency can be set higher than the first-order explosion frequency at the maximum engine speed in the engine operating range. Examples of torsional stiffness elements in the roll vibration reduction device include the crankshaft 11, the drive gear 31 and the driven gear 32 (gear tooth surface stiffness), and the rotor shaft 23.

[0037] In the roll vibration reducing apparatus of the embodiment, the torsional resonance frequency in the roll vibration reducing apparatus is set higher than the first-order explosion frequency at the maximum engine speed in the engine operating range through the following design calculation.

[0038] First, let the inertia moment of the main inertial system be J1[kg·m 2 ], and the inertia moment of the secondary inertia system is set to J2[kg·m 2], the reduction ratio is set to i[-], and the torsional rigidity is set to k[Nm / rad]. Furthermore, as a necessary condition for the Helen balancer, J2 = J1 × i. Furthermore, as shown in the following mathematical formula (1), the moment of inertia of the secondary inertial system is converted around the axis of the primary inertial system.

[0039] J2′=J2×i 2 [kg·m 2 ] …(1)

[0040] Next, as shown in the following mathematical formula (2), the two inertial systems (the primary inertial system and the secondary inertial system) are converted into the equivalent inertial system of one inertial system.

[0041]

[0042] Next, when there are a plurality of locations where torsion occurs between the primary inertial system and the secondary inertial system, the torsional rigidity is synthesized as shown in the following mathematical formula (3).

[0043]

[0044] Furthermore, the torsional resonance frequency f of this system is calculated by the following mathematical formula (4).

[0045]

[0046] In addition, when the number of cylinders is N[-] and the engine speed is Ne[rpm], the first-order explosion frequency fe of the four-stroke engine is calculated by the following mathematical formula (5).

[0047]

[0048] Therefore, the maximum engine speed Ne in the engine operating range is max [rpm], just set the maximum engine speed Ne max The first-order burst frequency fe max The inertia moment, torsional rigidity, and reduction ratio may be such as to satisfy the relationship of the following mathematical formula (6) with the torsional resonance frequency f.

[0049]

[0050] Based on the above considerations, in the roll vibration reduction apparatus of the embodiment, for example, with respect to Ne max =5000 [rpm] inline 3-cylinder engine, with a main inertia system with inertia moment J1 = 0.03 [kg·m 2 ]、Inertia moment of the secondary inertia system J2=0.03[kg·m 2], Helen balancer with reduction ratio i=1[-] and torsional stiffness k=50000[Nm / rad]. Figure 5 The transmission gain and phase of the torque transmitted to the secondary inertial system with respect to the torque of the primary inertial system at this time are shown.

[0051] exist Figure 5 In the engine operation range, the torsional resonance frequency is 290 [Hz], and the first-order explosion frequency at the maximum engine speed (5000 [rpm]) is 125 [kHz]. Therefore, the torsional resonance frequency is higher than the first-order explosion frequency at the maximum engine speed.

[0052] In addition, if Figure 6 The figure shows the results of estimating the effect of operating the engine 1 while generating a torque from a maximum instantaneous torque of +250 [Nm] to a minimum instantaneous torque of -150 [Nm] while sweeping the engine speed from 1100 [rpm] to 5000 [rpm] in the roll vibration reduction device of the embodiment. Figure 6 In FIG, the roll torque generated by the engine 1 is shown ( Figure 6 Engine in), roll torque generated by Helen balancer (rotor 21) ( Figure 6 Helen balancer in), and the roll torque ( Figure 6 Engine + Helen balancer). In addition, Figure 7 It will Figure 6 The enlarged view of the engine speed near 1100 [rpm] is shown in FIG. Figure 8 It will Figure 6 The figure is an enlarged view of the engine speed near 5000 [rpm].

[0053] from Figure 6 、 Figure 7 and Figure 8 It can be seen that the roll torque generated by the Helen balancer (the supporting reaction force of the Helen balancer) offsets the roll torque generated by the engine 1 (the roll reaction force of the engine 1), and the roll torque (roll torque acting on the power unit) obtained by adding the roll torque generated by the engine 1 and the roll torque generated by the Helen balancer can be reduced in the entire engine operating range.

[0054] In addition, in the roll vibration reducing apparatus of the embodiment, as Figure 9As shown, the torsional resonance frequency can also be set to be twice or more higher than the first-order explosion frequency at the highest engine speed in the engine operating range. For example, the torsional resonance frequency can be set to be higher than the second-order explosion frequency at the highest engine speed in the engine operating range. Figure 10 The torque waveform including the explosion second-order component of the engine 1 as shown can achieve the effect of reducing the roll vibration in the entire engine operating range.

[0055] In addition, in the roll vibration reduction apparatus of the embodiment, a rotating mass may be used instead of the motor generator 2 of the secondary inertia system.

[0056] In addition, in the roll vibration reduction device of the embodiment, there is a driving force transmission mechanism 3 that reverses the rotation of the crankshaft 11 and transmits it to the rotor 21 using a gear train that meshes with the drive gear 31 and the driven gear 32, but the mechanism for reversing the rotation of the crankshaft 11 and transmitting it to the rotor 21 is not limited to this.

[0057] (Variation 1)

[0058] Figure 11 : is a diagram showing an example of a roll vibration reduction device according to Modification 1. Figure 11 As shown, the roll vibration reducing apparatus according to the first modification includes a planetary gear mechanism 4 as a mechanism (driving force transmission mechanism) that reverses the rotation of the crankshaft 11 and transmits the reverse rotation to the rotor 21 .

[0059] The planetary gear mechanism 4 includes a ring gear 44 having a tooth surface formed on its inner circumference; a sun gear 41, which is coaxially arranged with the ring gear 44 and has a tooth surface formed on its outer circumference; a plurality of planetary gears 43 meshing with the sun gear 41 and the ring gear 44; and a carrier 42 rotatably supporting the planetary gears 43. The ring gear 44 is coaxially coupled to the crankshaft 11 of the engine 1 and is rotatable therewith. The sun gear 41 is coaxially coupled to the rotor shaft 23 of the motor generator 2 and is rotatable therewith.

[0060] In the planetary gear mechanism 4, by restricting the rotation of the carrier 42, the rotation of the crankshaft 11 is reversed by the ring gear 44, the planetary gears 43, and the sun gear 41 and transmitted to the rotor shaft 23. As a result, the rotation of the crankshaft 11 is reversed by the planetary gear mechanism 4 and transmitted to the rotor 21 via the rotor shaft 23, causing the rotor 21 to rotate in the opposite direction to the crankshaft 11.

[0061] Thus, in the roll vibration reducing device of Modification 1, the planetary gear mechanism 4 reverses the rotation of the crankshaft 11 and transmits it to the rotor 21 , thereby enabling the rotor 21 to function as a Helen balancer for reducing the roll vibration of the engine 1 accompanying the rotation of the crankshaft 11 .

[0062] In the roll vibration reducing apparatus of Modification 1, the torsional rigidity elements include, for example, the crankshaft 11 , each gear of the planetary gear mechanism 4 (gear tooth surface rigidity), and the rotor shaft 23 .

[0063] (Variation 2)

[0064] Figure 12 : is a diagram showing an example of a roll vibration reduction device according to a second modification. Figure 12 As shown, the roll vibration reducing apparatus according to the second modification includes a belt transmission mechanism 5 as a mechanism (driving force transmission mechanism) that reverses the rotation of the crankshaft 11 and transmits the reverse rotation to the rotor 21 .

[0065] The belt transmission mechanism 5 includes a crankshaft pulley 51, idler pulleys 52 and 53, a transmission belt 54, and a tension pulley 55. The crankshaft pulley 51 is coaxially coupled to the crankshaft 11 of the engine 1 and is rotatable therewith. The transmission belt 54 is rotatably wound around the crankshaft pulley 51 and the idler pulleys 52 and 53. The tension pulley 55 presses the transmission belt 54 from the outer circumference (back side) toward the crankshaft pulley 51, applying tension to the transmission belt 54. Furthermore, the tension pulley 55 is coaxially coupled to the rotor shaft 23 of the motor generator 2 and is rotatable therewith.

[0066] In the belt transmission mechanism 5, the crank pulley 51 rotates integrally with the rotation of the crankshaft 11, causing the transmission belt 54 to rotate in the same direction as the rotation of the crankshaft 11. Furthermore, the tension pulley 55 rotates in conjunction with the rotation of the transmission belt 54, rotating in the direction opposite to the rotation of the crankshaft 11. Therefore, in the belt transmission mechanism 5, the rotation of the crankshaft 11 is reversed by the crank pulley 51, the transmission belt 54, and the tension pulley 55 and transmitted to the rotor shaft 23. Thus, in the roll vibration device of Modification 2, the rotation of the crankshaft 11 is reversed by the belt transmission mechanism 5 and transmitted to the rotor 21 via the rotor shaft 23, causing the rotor 21 to rotate in the direction opposite to that of the crankshaft 11.

[0067] Thus, in the roll vibration reducing device of the second modification, the rotation of the crankshaft 11 is reversed and transmitted to the rotor 21 by the belt transmission mechanism 5 , thereby enabling the rotor 21 to function as a Helen balancer for reducing the roll vibration of the engine 1 accompanying the rotation of the crankshaft 11 .

[0068] In the roll vibration reduction device of Modification 2, the torsional rigidity element includes, for example, the crankshaft 11, the transmission belt 54 (longitudinal elastic), and the rotor shaft 23. The transmission belt 54 is not particularly limited, as long as it is an annular member such as a resin belt or a metal chain belt that can be wound around the crankshaft pulley 51. Furthermore, an auxiliary pulley for transmitting rotational drive force to an auxiliary device provided in the vehicle may be used in place of the idler pulleys 52 and 53 on which the transmission belt 54 is rotatably wound.

[0069] (Variation 3)

[0070] Figure 13 : is a diagram showing an example of a roll vibration reduction device according to Modification 3. Figure 13 As shown, the roll vibration reducing apparatus according to the third modification includes a belt transmission mechanism 6 as a mechanism (driving force transmission mechanism) that reverses the rotation of the crankshaft 11 and transmits the reverse rotation to the rotor 21 .

[0071] The belt transmission mechanism 6 includes a drive gear 61, a driven gear 62, a drive pulley 63, a driven pulley 64, a transmission belt 65, and a balance shaft 66. The drive gear 61 is coaxially coupled to the crankshaft 11 of the engine 1 and is rotatable integrally with the crankshaft 11. The driven gear 62, which meshes with the drive gear 61, is coaxially coupled to a balance shaft 66, which is arranged parallel to the crankshaft 11, and is rotatable integrally with the balance shaft 66. The drive pulley 63 is coaxially coupled to the balance shaft 66 and is closer to the end of the driven gear 62, and is rotatable integrally with the balance shaft 66. The driven pulley 64 is coaxially coupled to the rotor shaft 23 of the motor generator 2 and is rotatable integrally with the rotor shaft 23. The transmission belt 65 is rotatably wound around the drive pulley 63 and the driven pulley 64. The balance shaft 66 is provided to reduce pitch vibration of the engine 1.

[0072] In the belt transmission mechanism 6, the drive gear 61 rotates integrally with the rotation of the crankshaft 11, thereby transmitting rotation in the direction opposite to the rotation of the crankshaft 11 to the balance shaft 66 via the driven gear 62. Furthermore, when the balance shaft 66 rotates, the rotation of the balance shaft 66 is transmitted to the rotor shaft 23 via the drive pulley 63, the transmission belt 65, and the driven pulley 64, causing the rotor 21 to rotate in the same direction as the balance shaft 66. In other words, the rotor 21 rotates in the direction opposite to that of the crankshaft 11.

[0073] Thus, in the roll vibration reducing device of the third modification, the rotation of the crankshaft 11 is reversed and transmitted to the rotor 21 by the belt transmission mechanism 6 , thereby enabling the rotor 21 to function as a Helen balancer for reducing the roll vibration of the engine 1 accompanying the rotation of the crankshaft 11 .

[0074] In the roll vibration reduction device of Modification 3, the torsional rigidity element includes, for example, the crankshaft 11, the transmission belt 65 (longitudinal elastic), and the rotor shaft 23. The transmission belt 65 is not particularly limited as long as it is an annular member such as a resin belt or a metal chain belt that can be wound around the drive pulley 63.

Claims

1. A roll vibration reduction device for an internal combustion engine, characterized in that: include: a main inertial system configured to rotate integrally with a crankshaft of the internal combustion engine; a driving force transmission mechanism configured to transmit the rotational driving force of the crankshaft in a manner reversing the direction of rotation; as well as a secondary inertia system configured to rotate using the rotational driving force transmitted from the driving force transmission mechanism and configured to reduce the roll vibration of the internal combustion engine accompanying the rotation of the crankshaft by rotating in a direction opposite to the rotation direction of the crankshaft, wherein: The rotating electric machine included in the secondary inertia system includes a rotor, a stator, and a rotor shaft. The rotor is rotatably arranged on the same axis inside the stator. The rotor shaft is arranged on the same axis as the rotor. The rotational driving force is transmitted from the driving force transmission mechanism to the rotor shaft. In order to reduce the roll vibration, the rotor functions as a Helen balancer that rotates in a direction opposite to the rotation direction of the crankshaft. The torsional resonance frequency of the roll vibration reducing device is set to be higher than the first-order explosion frequency at the highest speed in a predetermined operating range of the internal combustion engine. The inertia moment, torsional rigidity and reduction ratio are set so that the first-order explosion frequency at the highest speed and the torsional resonance frequency satisfy the following mathematical formula: ， Among them, fe max is the first-order frequency of the burst at the highest speed, Ne max is the maximum speed, N is the number of cylinders, f is the torsional resonance frequency, k is the torsional rigidity, J is the moment of inertia.

2. The roll vibration reducing device for an internal combustion engine according to claim 1, wherein: The inertia moment of at least one of the primary inertial system and the secondary inertial system is set so that the torsional resonance frequency is set higher than the first-order explosion frequency.

3. The roll vibration reducing device for an internal combustion engine according to claim 1 or 2, wherein: The torsional rigidity of the torsional rigidity element in the roll vibration reducing device is set so that the torsional resonance frequency is set higher than the explosion first-order frequency.

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