Patent Description:
The present inventors have proposed in <CIT> that "it is possible to employ a mechanism or a link mechanism as a combination of an eccentric cam driven to rotate by an inverter motor and a beam member, for example" as repeated moment generation means in a conventional torsional fatigue testing machine.

On the other hand, there are a "vibration fatigue testing machine" described in <CIT> and a "fatigue testing machine" described in <CIT>, for example, as related arts in association with the present invention, although they are different from a torsional fatigue testing machine.

The "vibration fatigue testing machine" described in <CIT> includes "a mechanism that generates vibration by a motor rotating an unbalanced pendulum and imparting a load on a sample attached to a sample holder". Also, the "fatigue testing machine" described in Cited Document <NUM> has a function of "transmitting vibration generated in a direction orthogonal to a rotation shaft core to a specimen and imparting a repeated load on the test piece while an eccentric weight is caused to rotate about the rotation shaft core".

<CIT> discloses performing a test under a condition similar to that an engine is actually in operation, by installing a mechanism which repeatedly applies a simultaneous external bending force and external twisting force to the pin section and crank-web section.

<CIT> discloses inertia compensated materials fatigue testing machines of the below resonance type having an eccentric weight for producing an alternating centrifugal force to be applied to a specimen.

<CIT> discloses a vibration device for a vibration table with variable amplitude.

The conventional fatigue testing machines described in <CIT>, <CIT> and <CIT> and the like employ, as means for repeatedly imparting a torsional load or an axial load on test pieces, mechanisms that generate a repeated moment or axial vibration in shaft bodies by causing eccentric weights to rotate with members connected to the test pieces. However, since forces in up-down and left-right directions repeatedly act on the fatigue testing machines during testing due to centrifugal forces generated through rotation of the eccentric weights, relatively large vibration and noise are generated.

Therefore, in a case of a general-purpose fatigue testing machine with moment capacity of about <NUM>, for example, it is necessary to fix the fatigue testing machine on a heavy platform (for example, a concrete block) in order to forcibly curb vibration, and as a result, the fatigue testing machine that is actually used is a one-ton class large-scaled heavy product in the actual situation.

Thus, a problem to be solved by the present invention is to provide a repeated moment generation device capable of realizing size reduction, weight reduction, and noise reduction for a fatigue testing machine.

A repeated moment generation device according to the present invention includes: a principal shaft that is for transmitting a repeated torsional moment; two principal bearing members that rotatably hold the principal shaft; two lever members that are attached to the principal shaft at positions separated in a shaft center direction of the principal shaft in a state in which each of the lever members perpendicularly intersects a shaft center of the principal shaft; two principal eccentric weight rotors that are provided at shaft bodies that are rotatably and axially supported by the lever members in a state in which each of the two principal eccentric weight rotors is parallel to the principal shaft, at symmetrical positions with the principal shaft interposed therebetween in a region where the lever members face each other; two auxiliary eccentric weight rotors that are provided such that each of the two auxiliary eccentric weight rotors is rotatable about a shaft body that is parallel to the principal shaft, between two pairs of auxiliary bearing members provided at members that are continued from the principal bearing members; and drive means for causing the two principal eccentric weight rotors and the two auxiliary eccentric weight rotors to synchronously rotate, in which eccentricity directions of centers of gravity of the two principal eccentric weight rotors are different from each other by <NUM> degrees around shaft centers thereof, eccentricity directions of centers of gravity of the two auxiliary eccentric weight rotors are different from each other by <NUM> degrees around shaft centers thereof, and the eccentricity direction of the center of gravity of one of the two principal eccentric weight rotors and the eccentricity direction of the center of gravity of the auxiliary eccentric weight rotor located on the same side as the principal eccentric weight rotor with respect to the principal shaft are different from each other by <NUM> degrees around the shaft centers thereof.

In the repeated moment generation device, it is preferable that two centrifugal forces generated through rotation of the two principal eccentric weight rotors have mutually the same magnitude and have acting directions that are opposite by <NUM> degrees, and that two centrifugal forces generated through rotation of the two auxiliary eccentric weight rotors have mutually the same magnitude and have acting directions that are opposite by <NUM> degrees.

In the repeated moment generation device, it is preferable that a couple of forces defined by a product of two centrifugal forces generated through rotation of the two principal eccentric weight rotors and a distance between lines of action of the two centrifugal forces and a couple of forces defined by a product of two centrifugal forces generated through rotation of the two auxiliary eccentric weight rotors and a distance between lines of action of the two centrifugal forces have mutually the same magnitude and have opposite rotation directions.

In the repeated moment generation device, the two principal bearing members and the two pairs of auxiliary bearing members can be provided at a table member such that shaft centers of shaft bodies of the two principal eccentric weight rotors and shaft centers of shaft bodies of the two auxiliary eccentric weight rotors are parallel to each other.

Note that the repeated moment generation device can also include the following configuration requirements and it is thus possible to realize simplification and downsizing of the device.

According to the present invention, it is possible to provide a repeated moment generation device capable of realizing size reduction, weight reduction, and noise reduction for a fatigue testing machine.

Hereinafter, a repeated moment generation device <NUM> according to an embodiment of the present invention will be described on the basis of <FIG>. Note that some of components, such as a table <NUM> and a support member <NUM>, are displayed in a transparent manner to enhance visibility in <FIG>. Also, the reference signs described in the explanation in paragraphs [<NUM>] to [<NUM>] correspond only to the reference signs described in the drawings [<FIG>], respectively, and do not correspond to the reference signs described in the drawings other than the drawings [<FIG>].

First, a structure, a function, and the like of the repeated moment generation device <NUM> according to the present embodiment will be described on the basis of <FIG> and <FIG>. As illustrated in <FIG>, the repeated moment generation device <NUM> includes: a principal shaft <NUM> that is for transmitting a repeated moment; principal bearing members 2a, 2b that are provided to stand on an upper surface of the table <NUM> at a predetermined distance therebetween to rotatably hold the principal shaft <NUM>; a pair of lever members 3a, 3b that are attached to the principal shaft <NUM> at positions that are separated in a direction of a shaft center 1c of the principal shaft <NUM> in a state in which each of the lever members 3a and 3b perpendicularly intersects the principal shaft <NUM>; shaft bodies <NUM> and <NUM> that are provided such that the shaft bodies <NUM>, <NUM> are rotatable about shaft centers 4c, 5c (see <FIG>) that are parallel to the principal shaft <NUM>, respectively, at symmetrical positions with the principal shaft <NUM> interposed therebetween in a region where the lever members 3a, 3b face each other; two principal eccentric weight rotors <NUM>, <NUM> that are provided to be rotatable along with the shaft bodies <NUM>, <NUM> around the shaft centers 4c, 5c; and the like.

The table <NUM> is a quadrangular flat plate-shaped member and is maintained in a horizontal state by four support members <NUM> disposed at four corner portions 24c thereof on the lower surface side. The support members <NUM> have L-shape horizontal sections and are provided with bottom plates 25b on the lower surface side. The four corner portions 24c of the table <NUM> are fixed in a state in which the corner portions 24c are placed on upper surfaces 25a of the four support members <NUM>, respectively, and a quadrangular flat plate-shaped bottom table <NUM> is disposed on the bottom plates 25b located at the four positions.

The lower surface of the table <NUM> that is a member continued from the principal bearing members 2a, 2b is provided with a plurality of auxiliary bearing members 8a, 8b, 9a, 9b in a suspended manner, a shaft body <NUM> having a shaft center 10c (see <FIG>) that is parallel with the principal shaft <NUM> is disposed to be rotatable about the shaft center 10c between the facing auxiliary bearing members 8a, 8b, and a shaft body <NUM> having a shaft center 11c that is parallel with the principal shaft <NUM> is disposed to be rotatable about the shaft center 11c between the facing auxiliary bearing members 9a, 9b. The auxiliary eccentric weight rotor <NUM> is rotatable along with the shaft body <NUM>, and the auxiliary eccentric weight rotor <NUM> is rotatable along with the shaft body <NUM>.

Since the two principal eccentric weight rotors <NUM>, <NUM> and the two auxiliary eccentric weight rotors <NUM>, <NUM> have the same size, structure, function, and the like, the principal eccentric weight rotor <NUM> will be described below. As illustrated in <FIG>, the principal eccentric weight rotor <NUM> includes a columnar diameter expanded portion 7b that is formed at a part of the shaft body <NUM> and a weight member 7c that is attached with the diameter expanded portion 7b penetrating in a direction that is orthogonal to the shaft center 5c.

The weight member 7c includes a bolt member 7e that is screwed to penetrate through the diameter expanded portion 7b, a weight <NUM> that is attached to an end portion of the bolt member 7e, and a locking nut 7d that is screwed onto the bolt member 7e to lock the bolt member 7e at the diameter expanded portion 7b. A male screw is formed on the outer circumference of the bolt member 7e, and an end portion of the weight member 7c on the opposite side is provided with a short columnar-shaped stopper portion 7f with a diameter expanded as compared with the male screw portion.

The bolt member 7e having a male screw at the outer circumference thereof is screwed in a state in which it penetrates through the diameter expanded portion 7b having a female screw hole (corresponding to the female screw hole <NUM> in <FIG>), and it is possible to decenter a center of gravity <NUM> (see <FIG>) of the weight member 7c in a direction away from the shaft center 5c by causing the bolt member 7e to rotate about the shaft center thereof, causing the bolt member 7e to move in a longitudinal direction, and thereby changing the distance between the weight <NUM> and the shaft center 5c of the shaft body <NUM>.

If the principal eccentric weight rotor <NUM> rotates with rotation of the shaft body <NUM> that rotates due to a drive force of a motor <NUM> as will be described later in a state in which the center of gravity <NUM> of the weight member 7c is decentered from the shaft center 5c, then the weight member 7c also rotates about the shaft center 5c, and a centrifugal force 7a with the size determined by the amount of eccentricity of the center of gravity <NUM> and the rotation frequency is generated in the shaft center direction of the bolt member 7e. Since a direction in which the centrifugal force 7a acts rotates about the shaft center 5c, a force changing in up-down and left-right directions with the rotation is transmitted to the shaft body <NUM> and members coupled to the shaft body <NUM>. The principal eccentric weight rotor <NUM> and the two auxiliary eccentric weight rotors <NUM> and <NUM> also have functions that are similar to that of the principal eccentric weight rotor <NUM>.

As drive means for causing the two principal eccentric weight rotors <NUM> and <NUM> and the two auxiliary eccentric weight rotors <NUM> and <NUM> to synchronously rotate, the motor <NUM>, middle timing pulleys <NUM>, <NUM>, large timing pulleys <NUM>, <NUM>, small timing pulleys 19a, 19b, 20a, 20b, and timing belts <NUM>, <NUM>, <NUM> are included.

The middle timing pulley <NUM> and the large timing pulley <NUM> are attached to a rotation shaft 14a of the motor <NUM>, and the middle timing pulley <NUM> and the large timing pulley <NUM> are attached to the principal shaft <NUM> via a bearing. The rotation shaft 14a of the motor <NUM> is parallel with the principal shaft <NUM>, the middle timing pulley <NUM> and the large timing pulley <NUM> on the side of the motor <NUM> are located immediately below the middle timing pulley <NUM> and the large timing pulley <NUM> on the side of the principal shaft <NUM>, and the middle timing pulleys <NUM>, <NUM> and the large timing pulleys <NUM> and <NUM> are disposed to face each other such that the middle timing pulleys <NUM> and <NUM> are disposed in series and the large timing pulleys <NUM> and <NUM> are disposed in series, in the up-down direction.

The small timing pulleys 19a, 19b are attached to the shaft bodies <NUM>, <NUM>, and small timing pulleys 20a, 20b are attached to the shaft bodies <NUM>, <NUM>. The small timing pulleys 19a, 19b are disposed in series with the large timing pulley <NUM> interposed therebetween, and the small timing pulleys 20a, 20b are disposed in series with the large timing pulley <NUM> interposed therebetween. The sizes (outer diameters) of the small timing pulleys 19a, 19b, 20a, 20b are the same, the sizes (outer diameters) of the middle timing pulleys <NUM>, <NUM> are also the same, and the sizes (outer diameters) of the large timing pulleys <NUM>, <NUM> are also the same.

The middle timing pulley <NUM> and the middle timing pulley <NUM> are interlocked by the timing belt <NUM>, the small timing pulleys 19a, 19b and the large timing pulley <NUM> are interlocked by the timing belt <NUM>, and the small timing pulleys 20a, 20b and the large timing pulley <NUM> are interlocked by the timing belt <NUM>.

If the motor <NUM> is activated, the large timing pulley <NUM> and the middle timing pulley <NUM> attached integrally to the rotation shaft 14a rotate in the same direction at the same rotation frequency, the rotation of the middle timing pulley <NUM> is transmitted to the middle timing pulley <NUM> via the timing belt <NUM>, and the middle timing pulleys <NUM>, <NUM> rotate in the same direction at the same rotation frequency as those of the rotation shaft 14a of the motor <NUM>. The rotation of the middle timing pulley <NUM> is transmitted to the large timing pulley <NUM> integrated with the middle timing pulley <NUM> via the principal shaft <NUM>, and the large timing pulleys <NUM>, <NUM> thus rotate in the same direction at the same rotation frequency.

The rotation of the large timing pulley <NUM> is transmitted to the small timing pulleys 20a, 20b via the timing belt <NUM>, the rotation of the large timing pulley <NUM> is transmitted to the small timing pulleys 20a, 20b via the timing belt <NUM>, and the shaft bodies <NUM>, <NUM>, <NUM>, <NUM> to which the small timing pulleys 19a, 19b, 20a, 20b are attached, respectively, rotate in the mutually same direction at the same rotation frequency.

Therefore, the two principal eccentric weight rotors <NUM>, <NUM> and the two auxiliary eccentric weight rotors <NUM>, <NUM> mutually synchronously rotate in the same direction at the same rotation frequency as illustrated in <FIG>, which will be described later. Note that in the repeated moment generation device <NUM>, rotational center lines of the two principal eccentric weight rotors <NUM>, <NUM> are the same as the shaft centers 4c, 5c of the shaft bodies <NUM>, <NUM>, respectively, and rotational center lines of the two auxiliary eccentric weight rotors <NUM>, <NUM> are the same as the shaft centers 10c, 11c of the shaft bodies <NUM>, <NUM>, respectively.

In the repeated moment generation device <NUM> illustrated in <FIG>, the two principal eccentric weight rotors <NUM>, <NUM> are disposed such that eccentricity directions of the centers of gravity <NUM>, <NUM> (the directions of the centrifugal forces 6a, 7a) are different from each other by <NUM> degrees around the shaft centers 4c, 5c, of the shaft bodies <NUM>, <NUM> thereof as illustrated in <FIG>. Also, the two auxiliary eccentric weight rotors <NUM>, <NUM> are disposed such that eccentricity directions of the centers of gravity <NUM>, <NUM> thereof (the directions of the centrifugal forces 12a, 13a) are different from each other by <NUM> degrees around the shaft centers 10c, 11c of the shaft bodies <NUM>, <NUM> thereof. Furthermore, disposition is made such that the eccentricity direction of the principal eccentric weight rotor <NUM>, which corresponds to one of the two principal eccentric weight rotors, (the direction of the centrifugal force 6a) and the eccentricity direction of the auxiliary eccentric weight rotor <NUM> (the direction of the centrifugal force 12a) located on the same side as the principal eccentric weight rotor <NUM> with respect to the principal shaft <NUM> are different from each other by <NUM> degrees around the shaft centers 4c, 10c of the shaft bodies <NUM>, <NUM> thereof.

Next, effects, advantages, and the like of the two principal eccentric weight rotors <NUM>, <NUM> and the two auxiliary eccentric weight rotors <NUM>, <NUM> in the repeated moment generation device <NUM> illustrated in <FIG> will be described on the basis of <FIG>.

If the motor <NUM> is activated in the repeated moment generation device <NUM> illustrated in <FIG>, each of the two principal eccentric weight rotors <NUM>, <NUM> and the two auxiliary eccentric weight rotors <NUM>, <NUM> rotates in the clockwise direction (the arrow A direction) at the same rotation frequency as illustrated in <FIG>.

<FIG> display states in which the two principal eccentric weight rotors <NUM>, <NUM> and the two auxiliary eccentric weight rotors <NUM>, <NUM> rotate with elapse of time in order. The two principal eccentric weight rotors <NUM>, <NUM> rotate while maintaining a relationship in which the directions of the centrifugal forces 6a, 7a thereof are different from each other by <NUM> degrees around the rotational center lines (shaft centers 4c, 5c), and the two auxiliary eccentric weight rotors <NUM>, <NUM> rotate while maintaining a relationship in which the directions of the centrifugal forces 12a, 13a thereof are different from each other by <NUM> degrees around the rotational center lines (shaft centers 10c, 11c).

As illustrated in <FIG>, the two centrifugal forces 6a, 7a generated through rotation of the two principal eccentric weight rotors <NUM>, <NUM> have mutually the same magnitude and have acting directions that are opposite by <NUM> degrees, and the two centrifugal forces 12a, 13a generated through rotation of the two auxiliary eccentric weight rotors <NUM>, <NUM> have mutually the same magnitude and have acting directions that are opposite by <NUM> degrees.

Also, a couple of forces defined by a product of the two centrifugal forces 6a, 7a generated through rotation of the two principal eccentric weight rotors <NUM>, <NUM> and the distance between lines of action of the two centrifugal forces 6a, 7a and a couple of forces defined by a product of the two centrifugal forces 12a, 13a generated through rotation of the two auxiliary eccentric weight rotors <NUM>, <NUM> and the distance between lines of action of the two centrifugal forces 12a, 13a have mutually the same magnitude and have rotation directions that are opposite.

Furthermore, the two principal bearing members 2a, 2b and the two pairs of auxiliary bearing members 8a, 8b, 9a, 9b are disposed on the table <NUM> such that the shaft centers 4c, 5c of the shaft bodies <NUM>, <NUM> of the two principal eccentric weight rotors <NUM>, <NUM> and the shaft centers 10c, 11c of the shaft bodies <NUM>, <NUM> of the auxiliary eccentric weight rotors <NUM>, <NUM> are parallel to each other.

The two principal eccentric weight rotors <NUM>, <NUM> rotate while maintaining a relationship in which the directions of the centrifugal forces 6a, 7a thereof are different from each other by <NUM> degrees around the rotational center lines (shaft centers 4c, 5c), and the two auxiliary eccentric weight rotors <NUM>, <NUM> rotate while maintaining a relationship in which the directions of the centrifugal forces 12a, 13a thereof are different from each other by <NUM> degrees around the rotational center lines (shaft centers 10c, 11c).

Also, when the two principal eccentric weight rotors <NUM>, <NUM> and the two auxiliary eccentric weight rotors <NUM>, <NUM> rotate, the direction of the centrifugal force 6a of the principal eccentric weight rotor <NUM>, which is one of the two principal eccentric weight rotors, and the direction of the centrifugal force 12a of the auxiliary eccentric weight rotor <NUM> located on the same side as the principal eccentric weight rotor <NUM> with respect to the principal shaft <NUM> maintain a relationship in which they are different from each other by <NUM> degrees around the rotational center lines (shaft centers 4c, 10c) thereof.

Since vibration is generated by the two principal eccentric weight rotors <NUM>, <NUM> rotating about the rotational center lines (shaft centers 4c, 5c) thereof, and the vibration causes both end portions of the lever member 3b to alternately vibrate in the up-down direction via the shaft bodies <NUM>, <NUM>, the lever member 3b repeats minute seesaw movement around the shaft center 1c of the principal shaft <NUM>, and the principal shaft <NUM> integrated with the lever member 3b thus repeats minute forward/reverse rotation. Therefore, if a test piece (not illustrated) is set on extension of the shaft center 1c of the principal shaft <NUM>, then it is possible to impart a repeated load (repeated moment) on the test piece.

As illustrated in <FIG>, when the two principal eccentric weight rotors <NUM>, <NUM> and the two auxiliary eccentric weight rotors <NUM>, <NUM> rotate with the same amount of eccentricity at the same rotation frequency, centrifugal forces F, F, F, F with the same magnitude are generated in the shaft bodies <NUM>, <NUM>, <NUM>, <NUM>, respectively.

If these centrifugal forces F are considered separately as forces in two directions that are orthogonal to each other (a horizontal force component Fh and a vertical force component Fv), the horizontal force component Fh and the vertical force component Fv in the principal eccentric weight rotor <NUM> and the horizontal force component Fh and the vertical force component Fv in the principal eccentric weight rotor <NUM> have mutually the same force magnitude in the vertical direction and the horizontal direction and have force directions that are opposite by <NUM> degrees, and the forces in the vertical direction and the horizontal direction are thus cancelled out by each other and satisfy an equilibrium condition of force.

Similarly, the horizontal force component Fh and the vertical force component Fv in the auxiliary eccentric weight rotor <NUM> and the horizontal force component Fh and the vertical force component Fv in the auxiliary eccentric weight rotor <NUM> have mutually the same force magnitude in the vertical direction and the horizontal direction and have force directions that are opposite by <NUM> degrees, the forces in the vertical direction and the horizontal direction are thus cancelled out and satisfy the equilibrium condition of force.

Therefore, since all the forces generated in the structure including the two principal eccentric weight rotors <NUM>, <NUM> and the two auxiliary eccentric weight rotors <NUM>, <NUM> illustrated in <FIG> always satisfy the equilibrium condition of force, and the structure illustrated in <FIG> does not perform translational movement in all the directions, a test machine (not illustrated) coupled to the structure illustrated in <FIG> also does not perform translational movement.

While the horizontal force components Fh in the two principal eccentric weight rotors <NUM>, <NUM> out of the horizontal force components Fh and the vertical force components Fv act collinearly and thus do not generate a couple of forces, the vertical force components Fv have mutually the same magnitude and have directions that are opposite by <NUM> degrees, and act separately with a distance Lm between the shaft bodies <NUM> and <NUM>, and thus generate a couple of forces (that is, a moment) with the magnitude Mm = Fv × Lm defined by a product of the vertical force components Fv and the distance Lm, and the moment Mm is transmitted through the principal shaft <NUM>, acts on the test piece (not illustrated) coupled to the principal shaft <NUM>, and is further transmitted to the testing machine through a member (not illustrated) that fixes the test piece to the testing machine.

Also, while the horizontal force components Fh in the two auxiliary eccentric weight rotors <NUM>, <NUM> act collinearly and thus do not generate a couple of forces, the vertical force components Fv have mutually the same magnitude and have directions that are opposite by <NUM> degrees, act separately with a distance Ls between the shaft bodies <NUM>, <NUM>, thus generate a couple of forces (that is, a moment) with the magnitude Ms = Fv × Ls defined by a product of the vertical force components Fv and the distance Ls, and the moment Ms is transmitted to the table <NUM> through the auxiliary bearing members 8a, 8b, 9a, 9b that support the two auxiliary eccentric weight rotors <NUM>, <NUM>, and is then transmitted to the testing machine (not illustrated) coupled to the table <NUM>.

Since the rotation axes of the moment Mm and the moment Ms are parallel to each other, always have the same magnitude, and have rotation directions acting in opposite directions, the moment Mm and the moment Ms are canceled out and satisfy an equilibrium condition of moment. Therefore, the testing machine (not illustrated) does not perform rotational movement.

Also, the cancellation relationships of the centrifugal forces and the moments generated by the two principal eccentric weight rotors <NUM>, <NUM> and the two auxiliary eccentric weight rotors <NUM>, <NUM> are also established regardless of which directions the centrifugal forces F are directed to (regardless of what kind of postures the two principal eccentric weight rotors <NUM>, <NUM> and the two auxiliary eccentric weight rotors <NUM>, <NUM> are in around the shaft centers 4c, 5c, 10c, 11c) as illustrated in <FIG>.

In this manner, the centrifugal forces generated through rotation of the two principal eccentric weight rotors <NUM>, <NUM> and the two auxiliary eccentric weight rotors <NUM>, <NUM> theoretically do not serve as factors causing translational movement and rotational movement of the testing machine, and it is possible to achieve vibration reduction (theoretically, elimination of vibration) and noise reduction since it keeps the state with no motion during an operation.

Also, since it is not necessary to provide vibration control means, vibration isolation means, sound isolation means, and the like, if the aforementioned vibration reduction (theoretically, elimination of vibration) and noise reduction are realized, it is also possible to realize size reduction of the repeated moment generation device <NUM>. Moreover, since it is not necessary to increase the mass of the testing machine as in the related art for the purpose of curbing vibration, it is also possible to realize weight reduction of the testing machine.

Furthermore, since the repeated moment generation device <NUM> includes the following configuration requirements as illustrated in <FIG>, it is possible to realize simplification and downsizing of the device.

Note that the repeated moment generation device <NUM> described on the basis of <FIG> is an example of the repeated moment generation device according to the present invention.

Claim 1:
A repeated moment generation device (<NUM>), comprising:
a principal shaft (<NUM>) that is for transmitting a repeated torsional moment; two principal bearing members (2a, 2b) that rotatably hold the principal shaft (<NUM>); two lever members (3a, 3b) that are attached to the principal shaft (<NUM>) at positions separated in a shaft center direction of the principal shaft (<NUM>) in a state in which each of the lever members (3a, 3b) perpendicularly intersects a shaft center (1c) of the principal shaft (<NUM>); two principal eccentric weight rotors (<NUM>, <NUM>) that are provided at shaft bodies (<NUM>, <NUM>) that are rotatably and axially supported by the lever members (3a, 3b) in a state in which each of the two principal eccentric weight rotors (<NUM>, <NUM>) is parallel to the principal shaft (<NUM>), at symmetrical positions with the principal shaft (<NUM>) interposed therebetween in a region where the lever members (3a, 3b) face each other;
two auxiliary eccentric weight rotors (<NUM>, <NUM>) that are provided such that each of the two auxiliary eccentric weight rotors (<NUM>, <NUM>) is rotatable about a shaft body (<NUM>, <NUM>) that is parallel to the principal shaft (<NUM>), between two pairs of auxiliary bearing members (8a, 8b, 9a, 9b) provided at members that are continued from the principal bearing members (2a, 2b); and
drive means (<NUM>) for causing the two principal eccentric weight rotors (<NUM>, <NUM>) and the two auxiliary eccentric weight rotors (<NUM>, <NUM>) to synchronously rotate,
characterized in that:
eccentricity directions of centers of gravity of the two principal eccentric weight rotors (<NUM>, <NUM>) are different from each other by <NUM> degrees around shaft centers thereof;
eccentricity directions of centers of gravity of the two auxiliary eccentric weight rotors (<NUM>, <NUM>) are different from each other by <NUM> degrees around shaft centers thereof; and
the eccentricity direction of the center of gravity of one (<NUM>) of the two principal eccentric weight rotors (<NUM>, <NUM>) and the eccentricity direction of the center of gravity of one (<NUM>) of the two auxiliary eccentric weight rotors (<NUM>, <NUM>) located on the same side as one (<NUM>) of the two principal eccentric weight rotors (<NUM>, <NUM>) with respect to the principal shaft (<NUM>) are different from each other by <NUM> degrees around the shaft centers thereof.