Patent Description:
A vibration control device has been known that reduces fluctuation (torque ripple) of cyclic torque generated on a rotation driver, such as a motor, that drives an output shaft into rotation (for example, Patent Literature <NUM>).

<CIT> discloses: A vehicle including an engine, a generator, a motor, a driving member and a control device. The generator includes a rotor, a stator having a stator core with a winding wound thereon, and an inductance adjustment device that changes an inductance of the winding by changing magnetic resistance of a magnetic circuit for the winding that passes through the stator core. The current adjustment device adjusts a current outputted from the generator to the motor, which drives the driving member. The control device, upon receiving a request for increasing the current to be supplied to the motor, directs the inductance adjustment device to adjust the generator to operate in a state in which the inductance of the winding is low, directs the engine to increase a rotation speed thereof to increase the rotational power, and directs the current adjustment device to increase the output current of the generator.

<CIT> discloses: On the periphery of a rotor core , a field magnetic pole is projected in the d axial direction and a transformer magnetic circuit is projected in the q axial direction. The field magnetic pole is wound by a field magnetic coil and the transformer magnetic circuit is wound by a secondary coil. A high frequency voltage induced by the secondary coil is conducted to the field magnetic coil after rectification by a rectifying circuit shown in a diagram. The motor is excellent in reliability because of contactless power feeding despite that the rotor has a field coil.

<CIT> discloses: A rotation fluctuation reduction device comprises: an inertial body <NUM> to which a rotational driving force is supplied; a torque reduction mechanism part <NUM> which reduces rotation torque fluctuation of the inertial body; a rotational member to which rotations of the inertial body are transferred via the torque reduction mechanism part; a motor including a magnet that is provided in the rotational member and a coil that is fixed to a non-rotational member that is not rotated relatively to the rotational member, and opposes the magnet; and an LC circuit including a capacitor for temporarily storing power generated by the motor, storing power in the capacitor when a rotation speed of the rotational member is up, and supplying power stored in the capacitor to the coil by driving a switch when the rotation speed is down.

<CIT> discloses: An electromagnetic rotor drive assembly for use with an internal combustion engine, the electromagnetic rotor drive assembly including a conductive coil capable of generating a magnetic field upon energization; a rotor rotatably mounted proximate the conductive coil; and a magnet coupled to the rotor, the magnet responsive to the magnetic field to angularly displace the rotor; whereby the rotor fixedly couples to a crankshaft rotated by at least one piston reciprocally disposed within a cylinder; and whereby the conductive coil is energized at a predetermined time point associated with a position of the piston within the cylinder.

A conventional vibration control device employs: a magnet fixed to an output shaft; and a coil provided on the outer circumference of the magnet. In such a structure, voltage due to electromotive force generated in the coil along with rotational motion of the magnet increases as the rotation speed of the output shaft increases. Thus, a circuit including the coil inevitably needs to have a higher level of durability against high voltage. This makes such a circuit complicated and costly.

The present invention is directed to providing a vibration control device capable of reducing torque ripple attributable to a rotation driver while having a simpler configuration.

In order to achieve the above described object, a vibration control device according to claim <NUM> is disclosed.

Therefore, torque that operates to reduce torque fluctuation due to the rotation driver can be generated by the vibration control device, whereby the range of torque fluctuation due to combined torque obtained by combining torque generated on the rotation driver and torque due to the vibration control device can be made smaller than the range of torque fluctuation due to the rotation driver. Torque ripple due to the rotation driver can be thus reduced. Furthermore, the rotor is formed of a soft magnetic body. This hampers the rotor from generating electromotive force in the coils even when the rotor simply rotates, and thus hampers the vibration control device from operating like a power generator. Therefore, the level of durability against high voltage required of a circuit including the coils can be lowered, whereby the vibration control device can have a simpler configuration.

The vibration control device according to an aspect of the present invention further includes a second detector configured to detect a rotation speed of the rotor. The switching circuit includes a switch configured to switch between connecting and disconnecting the coils and the charger-discharger, and the control circuit disconnects the coils from the charger-discharger when the rotation speed is out of an effective rotation speed range of the vibration control device.

Therefore, torque that can reduce torque ripple that would be generated by the rotation driver can be more reliably generated on the vibration control device.

In the vibration control device according to an aspect of the present invention, a plurality of pairs of the coils are provided, the rotor includes a plurality of pairs of pole parts, the pole parts in each pair being provided with the rotation axis therebetween in such a manner that the paired pole parts protrude in radially opposite directions, and the pole parts are not less in number of pairs than the coils.

Therefore, the number of pole parts is set to a number corresponding to the fluctuation cycle of torque due to the rotation driver, whereby the fluctuation of torque due to the vibration control device can be generated on a cycle corresponding to the fluctuation cycle of the torque due to the rotation driver.

In the vibration control device according to an aspect of the present invention, a plurality of pairs of the coils share the switching circuit with one another.

In addition, switching control of the plurality of pairs of coils can be synchronized, whereby the probability of malfunctions of the vibration control device can be reduced.

In the vibration control device according to an aspect of the present invention, the coils provided in a pair are provided in such a manner as to be connectable to the charger-discharger in parallel.

Therefore, when the electrical conditions of lead wires that form the respective coils are the same except that the form of connection of each of the coils to the charger-discharger is parallel or serial, it is easier to reduce the inductance of the coils to a lower level than when the coils are connected in series. Here, a state in which the electrical conditions of lead wires are the same means that there is no substantial difference between the configurations of the coils except for the form of the connection, more specifically, that the total installation lengths of the lead wires are equal or that electrical resistance values generated by the same lengths of the lead wires are equal, for example.

In the vibration control device according to an aspect of the present invention, the coils provided in a pair are provided in such a manner as to be connectable to the charger-discharger in series.

Therefore, when the electrical conditions of lead wires that form the respective coils are the same except that the form of connection of each of the coils to the charger-discharger is parallel or serial, it is easier to raise the inductance of the coils than when the coils are connected in parallel.

A vibration control device according to an aspect of the present invention is capable of reducing torque ripple attributable to a rotation driver while having a simpler configuration.

The following describes embodiments according to the present invention with reference to the drawings but is not intended to limit the present invention. Conditions described below of different ones of the embodiments can be used in combination as appropriate. Some of the constituent elements may be excluded.

<FIG> illustrates an example of the main configurations of a rotation driver M provided with a vibration control device <NUM> in an embodiment and peripheral devices thereof. The rotation driver M is a rotation driver the output of which suffers cyclic torque fluctuation as with torque W1 illustrated in <FIG> described below. The rotation driver M is, for example, a reciprocating engine but may be an electric motor.

In <FIG>, an output shaft of the rotation driver M is coupled with a shaft S1 and extends from the rotation driver M. When the rotation driver M is in operation, the shaft S1 shaped in a cylinder is driven to rotate about the center of the cylinder. The shaft S1 may be the output shaft of the rotation driver M.

The rotation driver M illustrated in <FIG> is coupled with a gearbox G via the shaft S1. The gearbox G moves a shaft S2 in response to rotation driving force transmitted via the shaft S1. The shaft S2 extends from one side of the gearbox G. The one side is opposite to another side of the gearbox G from which the shaft S1 extends, with a housing of the gearbox G therebetween. The shaft S2 illustrated in <FIG> is driven to rotate in the same direction as the shaft S1. However, the shaft S2 may be driven to rotate in a direction opposite to a direction in which the shaft S1 is driven to rotate. The shaft S2 may receive driving force for motion other than rotation, such as linear motion, transmitted thereto. The gearbox G and the shaft S2 can be omitted. The shaft S1 may be coupled directly to a subject to be driven at the terminal end.

<FIG> is a sectional view taken along the A-A line of <FIG>. <FIG> is a schematic circuit diagram illustrating the main configuration of the vibration control device <NUM>. As illustrated in <FIG>, the shaft S1 is provided with the vibration control device <NUM>. The vibration control device <NUM> includes a rotor <NUM>, a stator <NUM>, coils <NUM>, a charger-discharger <NUM>, a switching circuit <NUM>, a detector <NUM>, and a control circuit <NUM>.

The rotor <NUM> is a soft magnetic body fixed to the shaft S1. A material of the rotor <NUM> is, for example, ferritic stainless steel but is not limited thereto. The material thereof may be any material that has high magnetic permeability while having sufficiently low capability to maintain magnetic force to such an extent as to cause the rotor <NUM> to function as a soft magnetic body. The rotor <NUM> rotates when the shaft S1 rotates.

The rotor <NUM> illustrated in <FIG> includes a pair of pole parts <NUM>, <NUM> provided with the shaft S1 therebetween in such a manner that the pole parts <NUM> protrude in radially opposite directions. Each of the pole parts <NUM> illustrated in <FIG> is a part of the rotor <NUM>. The part has a fan-like outer circumferential portion that widens toward the outside of the rotor <NUM>. However, this is an example of the form of the pole part <NUM> and is not a limiting example. The specific form thereof can be changed as appropriate.

The stator <NUM> is provided in a radial circumference of a rotation axis of the rotor <NUM>. The rotation axis of the rotor <NUM> in the first embodiment is the shaft S1. The stator <NUM> of the vibration control device <NUM> illustrated in <FIG> is fixed to the housing of the rotation driver M. However, the rotation driver M and the stator <NUM> may be separated from each other. The stator <NUM> is a frame-like body or a box-like body that internally includes a space in which the rotor <NUM> can rotate. When the stator <NUM> is a box-like body, the shaft S1 penetrates the box-like body in a rotatable state. The rotor <NUM> and the stator <NUM> in the first embodiment have, for example, a layered structure having ferritic stainless steel plates layered in a direction in which the shaft S1 extends. However, the structure is not limited thereto. The specific structure of the stator <NUM> can be changed as appropriate.

A pair of core parts <NUM>, <NUM> extending toward the shaft S1 is provided on the inner circumferential surface of the stator <NUM> illustrated in <FIG>. The outer circumferential portions of the pole parts <NUM> do not make contact with the inner circumferential portions of the core parts <NUM>, and the pole parts <NUM> are provided so as to be rotatable inside the stator <NUM>. The pair of core parts <NUM>, <NUM> is provided with a pair of the coils <NUM>, <NUM>. The coils <NUM> are provided in a pair with the shaft S1 therebetween by being fixed to the corresponding core parts <NUM> of the stator <NUM>.

The charger-discharger <NUM> is provided so as to be connectable to the pair of coils <NUM>, <NUM>. The charger-discharger <NUM> is, for example, a secondary battery such as a lithium-ion battery but may be any charge-discharge body that can be discharged by supplying power to the pair of coils <NUM>, <NUM> and charged by being supplied with power from the pair of coils <NUM>, <NUM>. The charger-discharger <NUM> may be, for example, a passive element that can store power, such as a capacitor. In the first embodiment, the pair of coils <NUM>, <NUM> are connected to the charger-discharger <NUM> in parallel when connected to the charger-discharger <NUM>.

The switching circuit <NUM> is provided so as to be able to switch connection of the pair of coils <NUM>, <NUM> to the charger-discharger <NUM>. The switching circuit <NUM> illustrated in <FIG> includes a first switch <NUM>, a second switch <NUM>, and a third switch <NUM>. The first switch <NUM> is provided capable of switching between connecting and disconnecting the positive electrode of the charger-discharger <NUM> and the pair of coils <NUM>, <NUM>. The second switch <NUM> is provided capable of switching between connecting and disconnecting the first switch <NUM> and the pair of coils <NUM>, <NUM>. The first switch <NUM> is connected to the second switch <NUM> via wiring <NUM>. The second switch <NUM> is connected to the coil <NUM> and the coil <NUM> via wiring <NUM>. The third switch <NUM> is provided capable of switching between connecting and disconnecting the negative electrode of the charger-discharger <NUM> and the pair of coils <NUM>, <NUM>. The charger-discharger <NUM> is connected to the third switch <NUM> via wiring <NUM>. The negative electrode side of the charger-discharger <NUM> to which the wiring <NUM> is connected is provided in such a manner as to be connected to the ground potential. In drawings such as <FIG>, the ground potential connected to the wiring <NUM> is denoted as GND (ground). The third switch <NUM> is connected to the pair of coils <NUM>, <NUM> via wiring <NUM>.

The wiring <NUM> is connected to the wiring <NUM> via a rectifier D1. The rectifier D1 causes current to flow in a direction from the wiring <NUM> to the wiring <NUM> and not to flow in a direction opposite to that direction. The wiring <NUM> is connected to the wiring <NUM> via a rectifier D2. The rectifier D2 causes current to flow in a direction from the wiring <NUM> to the wiring <NUM> and not to flow in a direction opposite to that direction. Each of the rectifier D1 and the rectifier D2 is, for example, an electrical element, such as a diode, having a rectification function, but may be a rectifying device.

The detector <NUM> functions as a first detector that detects the rotation angle of the rotor <NUM>. The detector <NUM> in the first embodiment detects the rotation angle of the rotor <NUM> on a predetermined cycle and outputs signals that indicate the rotation angle. The specific example of the detector <NUM> is not limited to one configured to directly detect the rotation angle of the rotor <NUM>. For example, when the rotation driver M includes a function to detect the rotation angle of the shaft S1, the control circuit <NUM> may be configured to be capable of acquiring the rotation angle of the rotor <NUM> in accordance with the rotation angle of the shaft S1 that is output from the rotation driver M. Obviously, a rotation angle detector, such as an encoder, provided independently of the rotation driver M may be provided to the rotor <NUM> or the shaft S1.

The control circuit <NUM> controls the operation of the switching circuit <NUM> in accordance with the rotation angle of the rotor <NUM>. The control circuit <NUM> includes a first controller <NUM> and a second controller <NUM>. The first controller <NUM> controls the operation of the second switch <NUM> and the third switch <NUM> in accordance with the rotation angle of the rotor <NUM>. The second controller <NUM> detects the rotation speed of the rotor <NUM> based on changes in rotation angle of the rotor <NUM> that are determined based on signals output from the detector <NUM> on a predetermined cycle. That is, the detector <NUM> and the second controller <NUM> in the first embodiment operate in cooperation to function as a second detector. Furthermore, the second controller <NUM> controls the operation of the first switch <NUM> so as to disconnect the pair of coils <NUM>, <NUM> from the charger-discharger <NUM> when the rotation speed of the rotor <NUM> is outside a predetermined rotation speed range. This function of the second controller <NUM> is described later. The control circuit <NUM> is, for example, an integrated circuit but is not limited thereto. The control circuit <NUM> may be any circuit or assembly of circuits that includes the functions of the first controller <NUM> and the second controller <NUM> and may be composed of a plurality of circuits.

<FIG> illustrates an example of a schematic configuration of a circuit including the coils <NUM>, the charger-discharger <NUM>, and the switching circuit <NUM>. The rotor <NUM>, the detector <NUM>, and the control circuit <NUM>, which are illustrated in <FIG>, are omitted in the schematic configuration of the circuit illustrated in drawings such as <FIG>. An ammeter A1 is provided between the charger-discharger <NUM> and the first switch <NUM> in the schematic configuration of the circuit illustrated in drawings such as <FIG>. Furthermore, an ammeter A2 is provided between the wiring <NUM> and the coils <NUM> in the schematic configuration of the circuit illustrated in drawings such as <FIG>. The ammeter A1 and the ammeter A2 can be omitted.

<FIG> illustrates an example of the relations of the rotation angle of the rotor <NUM> with a first period T1, a transition period T2, and a second period T3. Sectional views of the vibration control device <NUM> illustrated in <FIG> are sectional views taken along the A-A line of <FIG> as in <FIG>. Description given with reference to <FIG> assumes that the rotation angle of the rotor <NUM> illustrated in <FIG> is <NUM> degrees (θ [deg]). The pole parts <NUM> approach closest to the coils <NUM> when the rotation angle of the rotor <NUM> is <NUM> degrees. It is also assumed that the rotor <NUM> rotates counterclockwise in <FIG>, which illustrates the sectional views taken along the A-A line of <FIG>.

The first period T1 is a period in which the rotation angle of the rotor <NUM> ranges from -α degrees to β degrees. The transition period T2 is a period in which the rotation angle of the rotor <NUM> ranges from β degrees to γ degrees. The second period T3 is a period in which the rotation angle of the rotor <NUM> ranges from γ degrees to α degrees. Here, α > γ > β > <NUM>. More specifically, for example, when the rotation angle of the rotor <NUM> is D, the rotation angle of the rotor <NUM> in the first period T1 is such that -α ≥ D > β, the rotation angle of the rotor <NUM> in the transition period T2 is such that β ≥ D > γ, and the rotation angle of the rotor <NUM> in the second period T3 is such that γ ≥ D > α. The position of any of the equality signs used along with inequality signs can be changed as appropriate unless the change results in contradiction.

In the example illustrated in <FIG>, α = <NUM>. Accordingly, the first period T1 illustrated in <FIG> is a period in which the rotation angle of the rotor <NUM> ranges from -<NUM> degrees to β degrees over <NUM> degrees. The transition period T2 illustrated in <FIG> is a period in which the rotation angle of the rotor <NUM> ranges from β degrees to γ degrees. Here, β and γ are less than <NUM> degrees, and β < γ. The second period T3 illustrated in <FIG> is a period in which the rotation angle of the rotor <NUM> ranges from γ degrees to <NUM> degrees.

<FIG> illustrates the state of the circuit including the coils <NUM>, the charger-discharger <NUM>, and the switching circuit <NUM> during the first period T1. <FIG> illustrates the state of the circuit including the coils <NUM>, the charger-discharger <NUM>, and the switching circuit <NUM> during the transition period T2. <FIG> illustrates the state of the circuit including the coils <NUM>, the charger-discharger <NUM>, and the switching circuit <NUM> during the second period T3. <FIG> is a schematic graph illustrating the relations of current measured by an ammeter A1 and current measured by the ammeter A2 with each of the first period T1, the transition period T2, and the second period T3. <FIG> illustrates the relations between the torque W1 on the rotation driver M, torque W2 on the vibration control device <NUM>, and combined torque W3 obtained by combining the torque W1 and the torque W2.

Description given with reference to <FIG> and <FIG> assumes that the first switch <NUM> is on. That is, the pair of coils <NUM>, <NUM> is connected to the charger-discharger <NUM>. L1 in <FIG> denotes current measured by the ammeter A1. L2 in <FIG> denotes current measured by the ammeter A2.

As indicated by the torque W1 in <FIG>, the invention assumes that torque ripple due to torque fluctuation on the rotation driver M occurs on a <NUM>-degree cycle. The first period T1 includes a period in which torque on the rotation driver M becomes the smallest in the fluctuation of the torque. The second period T3 includes a period in which torque on the rotation driver M becomes the largest in the fluctuation of the torque. The transition period T2 is a period interposed between the first period T1 and the second period T3. <FIG> illustrates the lowest torque P1 and the highest torque P2 that the torque W1 takes. The vibration control device <NUM> in the first embodiment is provided on the assumption that torque ripple indicated by the torque W1 in <FIG> occurs on the rotation driver M.

When the rotation angle of the rotor <NUM>, which is detected by the detector <NUM>, corresponds to a rotation angle of the first period T1, the first controller <NUM> turns on both the second switch <NUM> and the third switch <NUM> as illustrated in <FIG>. Consequently, power is supplied from the charger-discharger <NUM> to the coils <NUM>, whereby the coils <NUM> are excited. Thus, in the first period T1, current flowing from the charger-discharger <NUM> toward the pair of coils <NUM>, <NUM> is measured by the ammeter A1 and the ammeter A2 as illustrated in <FIG>. Therefore, during a period with the rotation angle between -α degrees and β degrees illustrated in <FIG>, magnetic force acts in such a manner that the pair of pole parts <NUM>, <NUM> is attracted toward the pair of coils <NUM>, <NUM>.

In the first embodiment, while the rotation angle of the rotor <NUM> changes from -α degrees (-<NUM> degrees) toward <NUM> degrees, the magnetic force of the pair of coils <NUM>, <NUM> in the first period T1 attracts the pole parts <NUM> toward the coil <NUM>, thus generating positive torque on the rotor <NUM> to cause the rotation angle of the rotor <NUM> to become closer to <NUM> degrees, as indicated by the torque W2 in <FIG>. When the rotation angle of the rotor <NUM> reaches <NUM> degrees, the torque becomes <NUM>. Furthermore, when the rotation angle of the rotor <NUM> exceeds <NUM> degrees, the magnetic force attracts the pole parts <NUM> toward the coils <NUM>, thus generating negative torque on the rotor <NUM> to return the rotation angle of the rotor <NUM> to <NUM> degrees.

When the rotation angle of the rotor <NUM>, which is detected by the detector <NUM>, corresponds to a rotation angle of the transition period T2, the first controller <NUM> turns off the second switch <NUM> and turns on the third switch <NUM> as illustrated in <FIG>. This forms a closed circuit that includes the pair of coils <NUM>, <NUM>, the wiring <NUM>, the wiring <NUM>, the third switch <NUM>, and the rectifier D2, and current circulates within the closed circuit. The current L1 is not generated between the coils <NUM> and the charger-discharger <NUM> because a route in the closed circuit through which current circulates does not include the charger-discharger <NUM>, the first switch <NUM>, the second switch <NUM>, and the ammeter A1. Thus, in the transition period T2, the ammeter A1 does not measure current, as illustrated in <FIG>. In addition, the current L2 measured by the ammeter A2 is larger than in the first period T1. In the transition period T2, the current L2 flowing within the closed circuit slightly increases because of electromagnetic induction generated by the coils <NUM> that keeps on being excited by current that circulates within the closed circuit, and by changes in rotation angle of the rotor <NUM>. Therefore, in a period during which the rotation angle is between β degrees and γ degrees, which is illustrated in <FIG>, magnetic force that acts in such a manner as to attract the pair of pole parts <NUM>, <NUM> toward the pair of coils <NUM>, <NUM>, is slightly larger than in a period during which the rotation angle is between -α degrees and β degrees. In the transition period T2, an increase in current and a consequent rise in voltage are significantly smaller than when the rotor <NUM> is formed of a ferromagnetic body.

In the first embodiment, while the rotation angle of the rotor <NUM> changes from β degrees toward γ degrees, the magnetic force of the pair of coils <NUM>, <NUM> in the transition period T2 attracts the pole parts <NUM> toward the coils <NUM>, thus generating negative torque on the rotor <NUM> to return the rotation angle of the rotor <NUM> to <NUM> degrees (see <FIG>).

When the rotation angle of the rotor <NUM>, which is detected by the detector <NUM>, corresponds to a rotation angle of the second period T3, the first controller <NUM> turns off both the second switch <NUM> and the third switch <NUM> as illustrated in <FIG>. Consequently, a circuit is formed that has the rectifier D1 interposed between the pair of coils <NUM>, <NUM> and the positive electrode of the charger-discharger <NUM> and that has the rectifier D2 interposed between the pair of coils <NUM>, <NUM> and the negative electrode of the charger-discharger <NUM>. The rectifier D1 causes rectification by which current flows from the negative electrode of the charger-discharger <NUM> to the coils <NUM>. The rectifier D2 causes rectification by which current flows from the pair of coils <NUM>, <NUM> to the charger-discharger <NUM>. Therefore, current that has been circulating in the transition period T2 flows into the charger-discharger <NUM>. That is, in the second period T3, current from the pair of coils <NUM>, <NUM> becomes regenerative current and operates to charge the charger-discharger <NUM>. Thus, in the transition period T2, as illustrated in <FIG>, current flowing from the pair of coils <NUM>, <NUM> to the charger-discharger <NUM> is measured by the ammeter A1 and the ammeter A2. The regenerative current gradually decreases. In a part between the charger-discharger <NUM> and the first switch <NUM>, where the ammeter A1 is provided, current measured in the first period T1 and current measured in the second period T3 flow in opposite directions. Therefore, in <FIG>, the positive side represents rightward flow while the negative side represents leftward flow.

In the first embodiment, while the rotation angle of the rotor <NUM> changes toward α degrees (<NUM> degrees), the magnetic force of the pair of coils <NUM>, <NUM> in the second period T3 attracts the pole parts <NUM> toward the coils <NUM>, thus generating negative torque on the rotor <NUM> to return the rotation angle of the rotor <NUM> toward <NUM> degrees, as indicated in <FIG>. This negative torque decreases after the force that attracts the pole parts <NUM> toward the coils <NUM> hits a peak.

As described with reference to <FIG>, in the first embodiment, positive torque acts on the rotor <NUM> while the rotation angle of the rotor <NUM> changes from the -<NUM> degrees to <NUM> degrees. Thus, the positive torque acting on the rotor <NUM> is combined with torque including the lowest torque P1 and acting on the rotation driver M. This causes the combined torque W3 acting on the shaft S1 in the first period T1 to be higher than the torque W1 acting in the first period T1. Additionally, negative torque acts on the rotor <NUM> while the rotation angle of the rotor <NUM> changes from <NUM> degrees to <NUM> degrees. Thus, the negative torque acting on the rotor <NUM> is combined with torque including the highest torque P2 and acting on the rotation driver M. This causes the combined torque W3 acting on the shaft S1 in the second period T3 to be lower than the torque W1 acting in the second period T3. Consequently, as indicated by the combined torque W3 in <FIG>, torque fluctuates in a smaller range than the torque W1.

The first period T1, the transition period T2, and the second period T3 described with reference to <FIG> are cyclically repeated. In the first embodiment, the sequence of the first period T1, the transition period T2, and the second period T3 is repeated on a cycle of a half (<NUM> degrees) of a rotation angle change (<NUM> degrees) that corresponds to one rotation of the rotor <NUM>. That is, in the first embodiment, a range from -<NUM> degrees through <NUM> degrees to <NUM> degrees is set to one cycle, and a range from <NUM> degrees through <NUM> degrees to <NUM> degrees is also set to one cycle. The sequence of the first period T1 the transition period T2, and the second period T3 is repeated for two cycles each time the rotor <NUM> rotates once. In one cycle having the range from <NUM> degrees to <NUM> degrees, "<NUM> degrees" corresponds to "<NUM> degrees" in one cycle having the range from <NUM> degrees through <NUM> degrees to <NUM> degrees.

When n denotes the number of pole parts <NUM>, one cycle of torque ripple generated by the vibration control device <NUM> corresponds to a range of <NUM>/n degrees. Therefore, in the first embodiment, one cycle of torque ripple of the torque W2 generated by the vibration control device <NUM> corresponds to <NUM> degrees because n = <NUM>, as illustrated in <FIG>. Thus, the vibration control device <NUM> can be provided that generates the torque W2 that reduces the range of torque fluctuation due to the rotation driver M that generates the torque W1, which is second order fluctuation torque, as illustrated in <FIG>. In other words, the vibration control device <NUM> in which the number of pole parts <NUM> is n has a configuration corresponding to the rotation driver M that generates torque ripple of n-th order fluctuation.

In accordance with the specific mode of the vibration control device <NUM>, particularly with torque that is generated by the rotor <NUM>, the pole parts <NUM>, and the coils <NUM>, the specific values of β and γ are set so that: the gradual torque increase included in the torque W1 and the gradual torque decrease included in the torque W2 can correspond to each other in the transition period T2; and the value of the regenerative current can be zero or a value that is as close to zero as possible in a period during which the rotation angle of the rotor <NUM> changes from γ to α.

The torque W2 to be caused by the vibration control device <NUM>, which is described above with reference to <FIG>, is controlled so as to be generated when the rotation speed is within the predetermined rotation speed range. The rotation speed range is a range of the rotation speed of the shaft S1 such that the range of torque fluctuation due to the combined torque W3 is smaller than the range of torque fluctuation due to the torque W1. The rotation speed range corresponds to the specific mode of the vibration control device <NUM>, particularly to torque that is generated by the rotor <NUM>, the pole parts <NUM>, and the coils <NUM> in accordance with the rotation speed of the shaft S1. In other words, a range of the rotation speed of the shaft S1 at which the range of torque fluctuation due to the combined torque W3 is smaller than the range of torque fluctuation due to the torque W1, is the effective rotation speed range of the vibration control device <NUM>. Information that indicates the effective rotation speed range has been stored in the control circuit <NUM> (see <FIG>) in a state that allows the second controller <NUM> to acquire the information. The second controller <NUM> determines whether the rotation speed of the rotor <NUM> that is obtained based on a signal received from the detector <NUM> is included in the effective rotation speed range indicated by the information.

<FIG> illustrates an example in which the first switch <NUM> is turned on at a rotation speed at which the range of torque fluctuation due to combined torque W6 is larger than that of torque W1. Torque generated by the rotor <NUM>, the pole parts <NUM>, and the coils <NUM> increases or decreases in accordance with the rotation speed. Thus, as indicated by torque W51 in <FIG>, when the range of torque fluctuation generated by the rotor <NUM>, the pole parts <NUM>, and the coils <NUM> exceeds twice the range of torque fluctuation due to the torque W1, the range of torque fluctuation due to the combined torque W6 obtained by combining the torque W1 and the torque W51 is larger than the range of torque fluctuation due to the torque W1. When the rotor <NUM> is in such a rotation speed range, and operation such as excitation of the coils <NUM> described with reference to <FIG> becomes effective, the fluctuation range of the torque acting on the shaft S1 is increased by the vibration control device <NUM>. In <FIG>, torque W52 is hypothetical torque obtained by shifting the torque W51 in such a manner that the origin of the torque W51 matches the same position as that of the torque W1.

For the above reason, in the first embodiment, when the rotation speed of the rotor <NUM> is outside the predetermined rotation speed range, the second controller <NUM> turns off the first switch <NUM>. When the first switch <NUM> is turned off, the pair of coils <NUM>, <NUM> and the charger-discharger <NUM> becomes disconnected from each other. Consequently, no current is generated between the pair of coils <NUM>, <NUM> and the charger-discharger <NUM>. That is, it is possible to hamper the occurrence of a state in which the fluctuation range of torque that acts on the shaft S1 due to torque generated by the rotor <NUM>, the pole parts <NUM>, and the coils <NUM> is increased by the vibration control device <NUM>.

When the rotation speed of the rotor <NUM> is in the predetermined rotation speed range, the second controller <NUM> turns on the first switch <NUM> instead. Consequently, as described with reference to <FIG>, it is possible, by generating the torque W2, to generate the combined torque W3 having a torque fluctuation range smaller than that of the torque W1.

As described above, according to the first embodiment, the control circuit <NUM> causes the switching circuit <NUM> to operate so that: power is supplied to the pair of coils <NUM>, <NUM> from the charger-discharger <NUM> in the first period T1; power generated by the pair of coils <NUM>, <NUM> is supplied to the charger-discharger <NUM> in the second period T3; and a closed circuit that includes the pair of coils <NUM>, <NUM> but does not include the charger-discharger <NUM> is formed in the transition period T2. Consequently, the torque W2 can be generated that operates to reduce torque fluctuation due to the torque W1. Therefore, torque acting on the shaft S1 can be caused to turn into the combined torque W3 having a torque fluctuation range smaller than that of the torque W1. Torque ripple of the torque W1 due to the rotation driver M can be thus reduced. Furthermore, the rotor <NUM> is formed of a soft magnetic body. Thus, the vibration control device <NUM> can be hampered from operating like a power generator when the rotor <NUM> simply rotates. Therefore, the level of durability against high voltage required of a circuit including the coils <NUM> can be lowered, whereby the vibration control device <NUM> can have a simpler configuration.

Furthermore, the switching circuit <NUM> includes the first switch <NUM> configured to between connecting and disconnecting the pair of coils <NUM>, <NUM> and the charger-discharger <NUM>. The control circuit <NUM> disconnects the pair of coils <NUM>, <NUM> and the charger-discharger <NUM> from each other when the rotor <NUM> is out of the effective rotation speed range. Consequently, the torque W2 can be more reliably generated that operates to reduce the torque fluctuation range of the torque W1.

Particularly in the case where the rotation driver M is an engine mounted on an automobile, vibration due to torque ripple would tend to be larger when the rotation speed of the output shaft is in a range of low rotation speed. When the vibration control device <NUM> that is adapted for such a range of low rotation speed is attached to the engine, vibration can be substantially reduced.

With reference to <FIG>, an example is described in which the torque W1 has a well-shaped waveform as in the case with a sinusoidal wave. However, the relation between torque fluctuation due to the rotation driver M and the rotation angle and the relation between torque fluctuation due to the vibration control device <NUM> corresponding to the torque fluctuation due to the rotation driver M and the rotation angle, are not limited to those in the example. Even when the torque fluctuation due to the rotation driver M has a waveform different from a sinusoidal wave, the same advantages can be provided by: exciting the coils <NUM> at a time when torque due to the rotation driver M becomes smaller than the average of the torque of the rotation driver M; and supplying regenerative power from the coils <NUM> to the charger-discharger <NUM> at a time when torque due to the rotation driver M becomes larger than the average of the torque of the rotation driver M.

<FIG> illustrates an example of a schematic configuration of a circuit including coils <NUM>, the charger-discharger <NUM>, and the switching circuit <NUM> in a modification. In the first embodiment, the pair of coils <NUM>, <NUM> is connected to the charger-discharger <NUM> in parallel when connected to the charger-discharger <NUM>, but the connection example is not limited thereto. As illustrated in <FIG>, a pair of coils <NUM>, <NUM> may be connected to the charger-discharger <NUM> in series when connected to the charger-discharger <NUM>. The pair of coils <NUM>, <NUM> illustrated in <FIG> has the same configurations as the pair of coils <NUM>, <NUM> except for being connected to the charger-discharger <NUM> in series.

According to the modification, it is easier to increase the inductance of the pair of coils <NUM>, <NUM> than in first embodiment.

<FIG> is a sectional view illustrating the main configuration of a vibration control device 1A in a second embodiment. <FIG> is a diagram illustrating an example of a schematic configuration of a circuit including coils 30A, the charger-discharger <NUM>, and the switching circuit <NUM> in the second embodiment.

A rotor 10A included in the vibration control device 1A in the second embodiment includes a plurality of pairs of pole parts 11A, and the pole parts 11A in each pair are provided with the shaft S1 therebetween in such a manner that the pole parts 11A protrude in radially opposite directions. <FIG> exemplifies a configuration in which the rotor 10A includes <NUM> pairs of pole parts 11A, or <NUM> pole parts 11A in total. Thus, torque ripple is generated by the vibration control device 1A on a cycle of <NUM> degrees. Therefore, the vibration control device 1A can be used as a configuration adapted for the rotation driver M that generates torque ripple of 24th order fluctuation.

The number of pole parts 11A is equal to or greater than the number of coils 30A. In the configuration illustrated in <FIG>, the number of pole parts 11A is equal to the number of coils 30A. That is, <NUM> pairs of coils 30A, or <NUM> coils 30A in total, are provided with the shaft S1 therebetween. A stator 20A is provided in a form suitable for supporting the coils 30A. The number of core parts 21A corresponds to the number of coils 30A.

The coils 30A share the switching circuit <NUM> with one another. Specifically, as exemplified in <FIG>, all of the coils 30A are connected in parallel and share with one another the first switch <NUM>, the second switch <NUM>, the third switch <NUM>, the rectifier D1, the rectifier D2, which are provided in a route through which the coils 30A are electrically connected to the charger-discharger <NUM>. In other words, the configuration illustrated in <FIG> is the same as the configuration illustrated in <FIG> except for having a larger number of coils 30A in place of the two coils <NUM> in the configuration illustrated in <FIG>.

All of the coils 30A are connected to the charger-discharger <NUM> in parallel in <FIG>. However, this is not a limiting example. For example, as in the configuration illustrated in <FIG>, all of the coils 30A may be connected to charger-discharger <NUM> in series. Another configuration may be employed in which, while connection between the paired coils 30A is either one of the parallel connection and the serial connection, connection between the pairs of coils 30A, 30A is the other of the parallel connection and the serial connection. That is, the serial connection and the parallel connection may be employed concurrently.

In the second embodiment, the cycle in which connection between the coils 30A and the charger-discharger <NUM> is switched corresponds to the number of pole parts 11A. That is, for example, α = <NUM> in the second embodiment.

The rotor 10A, the pole parts 11A, the stator 20A, the core parts 21A, and the coil 30A in the second embodiment each have the same configuration as the corresponding one of the rotor <NUM>, the pole parts <NUM>, the stator <NUM>, the core parts <NUM>, and the coils <NUM> in the first embodiment unless otherwise described with reference to <FIG> and <FIG>. The vibration control device 1A has the same configuration as the vibration control device <NUM> unless otherwise described above.

According to the second embodiment, the number of pole parts 11A is set to a number corresponding to the fluctuation cycle of torque due to the rotation driver M, whereby the fluctuation of torque due to the vibration control device 1A can be generated on a cycle corresponding to the fluctuation cycle of the torque due to the rotation driver M.

In addition, switching control of the plurality of pairs of coils 30A can be synchronized. Thus, the configuration illustrated in <FIG> can eliminate the possibility of malfunctions that would occur when the plurality of pairs of the coils 30A operate asynchronously. Therefore, malfunctions of the vibration control device 1A can be reduced.

<FIG> is a sectional view illustrating the main configuration of a vibration control device 1B in a third embodiment. The number of the pairs of pole parts 11B included in the vibration control device 1B in the third embodiment is larger than the number of the pairs of coils 30B. In the configuration illustrated in <FIG>, two pairs of coils 30B, or four coils 30B in total, are provided with the shaft S1 therebetween. A stator 20B is provided in a form suitable for supporting the coils 30B. The number of core parts 21B corresponds to the number of coils 30B.

In the third embodiment, the cycle in which connection between the coils 30B and the charger-discharger <NUM> is switched corresponds to the number of pole parts 11B. That is, in the third embodiment, for example, α = <NUM> as in the second embodiment.

The rotor 10B, the pole parts 11B, the stator 20B, the core parts 21B, and the coil 30B in the third embodiment each have the same configuration as the corresponding one of the rotor 10A, the pole parts 11A, the stator 20A, the core parts 21A, and the coils 30A in the second embodiment unless otherwise described with reference to <FIG>. The vibration control device 1B has the same configuration as the vibration control device <NUM> unless otherwise described above.

Claim 1:
A vibration control device comprising:
a rotor (<NUM>) and fixed to an output shaft of a rotation driver or to a shaft that rotates in conjunction with the output shaft, the rotor (<NUM>) being configured to rotate in response to rotation of the output shaft;
a stator (<NUM>) provided in a radial circumference of a rotation axis of the rotor (<NUM>);
coils (<NUM>) fixed to the stator (<NUM>) and provided in a pair with the rotation axis therebetween;
a charger-discharger (<NUM>) provided in such a manner as to be connectable to the coils (<NUM>);
a switching circuit (<NUM>) provided capable of switching between connecting and disconnecting the coils (<NUM>) and the charger-discharger (<NUM>);
a first detector (<NUM>) configured to detect a rotation angle of the rotor (<NUM>); and
a control circuit (<NUM>) configured to control operation of the switching circuit (<NUM>) in accordance with the rotation angle of the rotor (<NUM>),
characterised in that
the rotor (<NUM>) is formed of a soft magnetic body, and
the control circuit (<NUM>) causes the switching circuit (<NUM>) to operate in such a manner that
power is supplied from the charger-discharger (<NUM>) to the coils (<NUM>) when the rotation angle of the rotor (<NUM>) corresponds to a first period (T1) of a predetermined cycle, the first period (T1) including a period in which torque generated on the rotation driver becomes the smallest in fluctuation of the torque in the predetermined cycle,
power generated by the coils (<NUM>) is supplied to the charger-discharger (<NUM>) when the rotation angle of the rotor (<NUM>) corresponds to a second period (T3) of the predetermined cycle, the second period (T3) including a period in which the torque becomes the largest in the predetermined cycle, and that
a closed circuit including the coils (<NUM>) and without including the charger-discharger (<NUM>) is formed such that no current is generated between the charger-discharger (<NUM>) and the coils (<NUM>), when the rotation angle of the rotor (<NUM>) corresponds to a transition period (T2) after the first period (T1) before the second period (T3), wherein the sequence of the first period (T1), the transition period (T2) and the second period (T3) is repeated in accordance with the rotation of the rotor (<NUM>).