Electromagnetic actuator, and active vibration damper and fluid-filled active vibration damping device using the same

An electromagnetic actuator including: a stator; a mover attached displaceable in relation to the stator; a plurality of plate springs elastically coupling the stator and the mover; and a coil member attached to one of the stator and the mover. Each of the plate springs includes an outer circumference attachment part and a center attachment part respectively attached to one and another of the stator and the mover. A plurality of spiral-shaped connection arm parts are provided at equal intervals in a circumferential direction radially between the outer circumference attachment part and the center attachment part so as to extend in a radial direction while being inclined in the circumferential direction. The plate springs overlap in a thickness direction and all of the plate springs are mutually formed with a same material and in a same shape.

INCORPORATED BY REFERENCE

The disclosure of Japanese Patent Application No. 2014-005632 filed on Jan. 16, 2014 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electromagnetic actuator by which a mover is driven in relation to a stator by energization to a coil, and to an active vibration damper and a fluid-filled active vibration damping device using the same.

2. Description of the Related Art

From the past, an electromagnetic actuator has been known as one type of vibration damping actuator used for actively controlling the vibration damping characteristics of a vibration damping device by applying active oscillation force to a member subject to vibration damping. With the electromagnetic actuator, the mover is attached so as to be displaceable relative to the stator, and by energization to a coil member attached on one of either the stator or the mover, the mover is driven in relation to the stator.

However, as shown in Japanese Patent No. JP-B-4852030, with the electromagnetic actuator, the stator and the mover are linked to each other by a plate spring, and by elastic deformation of the plate spring in the thickness direction, displacement of the mover in relation to the stator is allowed, and the mover and stator are aligned to each other in the radial direction of the plate spring.

Also, with JP-B-4852030, so that sufficient displacement is allowed of the mover in the thickness direction of the plate spring, a plurality of lightening holes are formed on the plate spring, and the plate spring has a constitution with which a center attachment part attached to the mover and an outer circumference attachment part attached to the stator are integrally linked to each other by a plurality of connection arm parts. This connection arm part extends in the radial direction while being inclined in the circumferential direction, with one end being integrally connected to the center attachment part, and the other end being integrally connected to the outer circumference attachment part.

Furthermore, with the electromagnetic actuator, as with JP-B-4852030, there are cases when a plurality of plate springs are used overlapping. In this case, the plate spring material, thickness dimension and the like can be set individually according to the required spring characteristics or the like, so with a plurality of plate springs, there are cases when these will be different from each other.

However, when palate springs with different materials, thickness dimensions and the like are used overlapping, due to differences in deformation volume in relation to ambient temperature changes, there can be mutual differences in the shape of the plate springs with a thickness direction view (particularly the shape of the connection arm part), and by local stress concentration occurring at the connection arm part, there is the risk of a decrease in durability of the plate springs.

SUMMARY OF THE INVENTION

The present invention was created with the circumstances described above as the background, and the problem it is to address is to provide an electromagnetic actuator of a novel structure for which it is possible to set the spring constant of the plate springs to be large, and to increase the durability of the plate springs, as well as an active vibration damper and a fluid-filled active vibration damping device using the same.

Following, we will describe modes of the present invention created for addressing this kind of problem. The constitutional elements used with each mode noted hereafter can be used in as many combinations as are possible.

Specifically, a first mode of the present invention provides an electromagnetic actuator including: a stator; a mover attached displaceable in relation to the stator; a plurality of plate springs elastically coupling the stator and the mover; and a coil member attached to one of the stator and the mover, the coil member being energized to generate a magnetic field that exerts a force on the mover to drive the mover in relation to the stator, wherein each of the plate springs includes an outer circumference attachment part and a center attachment part respectively attached to one and another of the stator and the mover, a plurality of spiral-shaped connection arm parts are provided at equal intervals in a circumferential direction between the outer circumference attachment part and the center attachment part in a radial direction so as to extend in the radial direction while being inclined in the circumferential direction, and the plate springs overlap in a thickness direction and all of the plate springs are mutually formed with a same material and in a same shape.

With this kind of electromagnetic actuator constituted according to the first mode, a plurality of the plate springs that link the stator and the mover overlap in the thickness direction, so it is possible to set the spring constant in the thickness direction to be large without making the thickness of each plate spring large. Therefore, when the mover undergoes drive displacement in relation to the stator, while the spring constant in the thickness direction is set to be large for the overall plate spring, it is possible to prevent the distortion of each plate spring from becoming markedly large.

Furthermore, since the plurality of plate springs are mutually formed with the same material and in the same shape, when the plate spring has swelling deformation or contraction deformation due to temperature changes, the deformation volume of those plate springs are equal to each other. Therefore, having stress and thus distortion concentrate on a specific plate spring due to a difference in deformation volume is prevented, and durability is improved.

On the plate springs for which the outer circumference attachment part and the enter attachment part are attached one each to the stator and the mover, stress is mainly applied by swelling deformation or contraction deformation in the length direction of the connection arm part, but by the plurality of plate springs being mutually formed with the same material and in the same shape, the linear expansion coefficient of those plate springs are mutually the same. In addition to that, by having the thickness dimension of the plurality of plate springs be mutually the same, the heat capacity of those plate springs is also mutually the same, and since the plurality of plate springs are heated or cooled in roughly the same manner in relation to changes in external temperature or the like, the deformation volume of those plate springs is more precisely kept roughly the same.

Also, by constituting a plurality of plate springs with a single part, it is possible to reduce the number of types of parts, and to improve manufacturing efficiency.

A second mode of the present invention provides the electromagnetic actuator according to the first mode, wherein the plate springs are matched to mutually a same position in the circumferential direction.

With the second mode, when the mover is driven and displaced in relation to the stator, and the plurality of plate springs are elastically deformed in the thickness direction, the deformation volume and deformation mode of each part of those plate springs are mutually the same, and the occurrence of noise due to interference between plate springs or stress concentration due to deformation differences or the like are avoided. In fact, even when the connection arm parts of the plurality of plate springs are deformed due to temperature changes, the connection arm parts of those plate springs maintain the same shape and the same orientation in the circumference direction, so noise due to interference between plate springs and stress concentration are avoided in relation to elastic deformation in the thickness direction of the plate springs due to driving of the mover.

A third mode of the present invention provides the electromagnetic actuator according to the first or second mode, wherein an outer circumference spacer is interposed between overlapping surfaces of the outer circumference attachment parts of the plate springs, a center spacer is interposed between overlapping surfaces of the center attachment parts of the plate springs, and the connection arm parts of the plate springs are separated from each other in the thickness direction.

With the third mode, when the mover is driven and displaced relative to the stator, and the connection arm part of the plate spring is elastically deformed in the thickness direction, it is possible to prevent the connection arm parts of the plurality of plate springs from rubbing against each other, and to prevent the occurrence of noise. In particular, by interposing spacers respectively between overlapping surfaces of the outer circumference attachment parts and the center attachment parts with the connection arm parts separated, it is possible to prevent the occurrence of noise while ensuring the free length of the connection arm parts and realizing the required spring characteristics and durability. The outer circumference parts and the center attachment parts sandwiching the spacers are attached one each to the stator and the mover, so there is not a problem of rubbing or the like of the spacers, the outer circumference attachment parts, and the center attachment parts.

A fourth mode of the present invention provides an active vibration damper including an actuator that is attached to a member subject to vibration damping and applies an oscillation force thereto, wherein the actuator is composed of an electromagnetic actuator according to any one of the first through third modes, and the stator of the electromagnetic actuator is attached to the member subject to vibration damping, and the mover is elastically supported on the member subject to vibration damping via the plate springs.

With this kind of active vibration damper of a constitution according to the fourth mode, by using the electromagnetic actuator of the present invention, even if the plurality of plate springs linking the mover and stator are repeatedly deformed due to oscillation, the distortion of those plate springs is reduced, so durability is advantageously ensured, and high reliability is realized.

A fifth mode of the present invention provides a fluid-filled active vibration damping device including: a first mounting member; a second mounting member; a main rubber elastic body elastically coupling the first and second mounting members; a pressure-receiving chamber a portion of whose wall is constituted by the main rubber elastic body and in which a non-compressible fluid is sealed, while another portion of the wall of the pressure-receiving chamber being constituted by an oscillation member; and an actuator that does oscillation driving of the oscillation member, wherein the actuator is composed of an electromagnetic actuator according to any one of the first through third modes, and the stator of the electromagnetic actuator is attached to the second mounting member, and the mover is attached to the oscillation member.

With this kind of active vibration damping device constituted according to the fifth mode, by using the electromagnetic actuator of the present invention as the actuator that does oscillation driving of the oscillation member, even if the plurality of plate springs that link the mover and the stator are repeatedly deformed due to oscillation, the distortion of those plate springs is reduced, so durability is advantageously ensured, and high reliability is realized.

With the present invention, since a plurality of plate springs overlap in the thickness direction, it is possible to set the spring constant in the thickness direction to be large without markedly increasing the thickness of each plate spring, and a high degree of freedom for the required spring characteristics is realized while suppressing distortion of the plate springs in relation to deformation in the thickness direction. Furthermore, by the plurality of plate springs being mutually formed with the same material and in the same shape, the deformation volume of those plate springs in relation to temperature changes is roughly mutually the same, so stress concentration on a specific plate spring due to differences in deformation volume is avoided, and durability is improved.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Following we will describe an embodiment of the present invention while referring to the drawings.

FIGS. 1 and 2show an active vibration damper10as a first embodiment of the present invention. This active vibration damper10is equipped with an electromagnetic actuator12as an actuator, and by oscillation force of the electromagnetic actuator12being applied to a vehicle body14as a member subject to vibration damping, the vibration is decreased by offset. With the description below, the vertical direction means the vehicle vertical direction in a vehicle mounted state, and means the vertical direction inFIG. 1which is the oscillation direction of the electromagnetic actuator12, and the front-back direction means the vertical direction inFIG. 2which is the vehicle front-back direction in the vehicle mounted state.

In more detail, the electromagnetic actuator12is equipped with a stator16and a mover18. The stator16has a constitution with a cover member22and a coil member24attached to a base member20fixed on the vehicle body14.

The base member20has a roughly cylindrical shape with a bottom facing the reverse, and a lower through hole26that pierces vertically is formed on the center part of the upper base wall part. Furthermore, on a lower opening edge part of the base member20, a flange part28that expands to the outer circumference side is formed across the entire circumference, and a pair of base attachment pieces30,30that are larger and project to the outer circumference side are formed in the lateral radial direction. Bolt holes32are respectively formed piercing vertically on the pair of base attachment pieces30,30.

The cover member22has a roughly cylindrical shape with a bottom reverse facing the depth bottom, an upper base step part34is formed near the upper base wall part, an opening step part36is provided on the opening part, and the diameter becomes larger in steps facing downward which is the opening side. Also, the cover member22is equipped with a pair of cover attachment pieces38,38laterally in the radial direction on the opening edge part that has a large diameter. The pair of cover attachment pieces38,38have a plate shape extending out downward and for which the lower edge part is curved and extends laterally to the outside, and bolt holes40are formed piercing vertically on the lower edge part extending laterally outward.

Then, the cover member22has the pair of cover attachment pieces38,38overlapping in the radial direction on the outer circumference surface of the base member20, and overlapping vertically on the pair of base attachment pieces30,30, and aligned to each other. The bolt holes32,32of the pair of base attachment pieces30,30and the bolt holes40,40of the pair of cover attachment pieces38,38are aligned to each other.

Also, the coil member24is arranged between the base member20and the cover member22. The coil member24has a constitution for which a coil44is wound onto a bobbin42. The bobbin42is a hard member formed using a nonmagnetic material such as synthetic resin or the like, and overall has a roughly cylindrical shape with a bottom, and has coil44wound on it. Furthermore, a bottom wall part46of the bobbin42which has a thick wall is equipped with an upper through hole48piercing vertically at the radial direction center part, and projects in the radial direction outward across the entire circumference, and a power feed connector50is integrally formed on a part of the circumference. The power feed connector50projects facing backward from the bottom wall part46of the bobbin42, and has an overturned roughly cylindrical shape with a bottom opening toward the rear, and one end of a connector metal fitting52embedded in the bottom wall part46of the bobbin42projects to the inner circumference side of the power feed connector50. The other end of the connector metal fitting52is connected to the coil44.

Then, with the coil member24, the outer circumference end part of the bottom wall part46is sandwiched vertically between the upper base wall part of the base member20and the opening step part36of the cover member22, and is installed between the base member20and the cover member22. Also, the power feed connector50of the coil member24projects facing backward from between the base member20and the cover member22. Between the overlapping surfaces of the bottom wall part46of the bobbin42and the base member20and the cover member22are respectively sealed using ring shaped sealing rubbers54and56, and penetration of foreign matter such as dust, water or the like is prevented.

The mover18is attached to the stator16constituted in this way. The mover18has a constitution with which a permanent magnet60is fixed to a yoke metal fitting58. The yoke metal fitting58is formed with a ferromagnetic material such as iron or the like, and overall has a thick walled round block shape, and at the radial direction middle part, a circumferential groove62that opens at the bottom surface is formed extending in a circumferential direction ring shape. By doing this, on the yoke metal fitting58, a center column part64with a roughly round column shape is formed on the inner circumference side of the circumferential groove62, and a roughly cylindrical shaped outer circumference tube part66is formed on the outer circumference side of the circumferential groove62, and at the top end, the center column part64and the outer circumference tube part66are integrally linked by a roughly disk shaped middle plate part68.

Furthermore, at the radial direction center part of the yoke metal fitting58, a coupling projection70projecting upward with a small diameter roughly round column shape is integrally formed, and a screw hole72opened at the top surface extending on the center axis is formed on the coupling projection70. Furthermore, at the radial direction center part of the yoke metal fitting58, a rod part74projecting downward is integrally formed, and on the rod part74, a screw part76projecting downward is integrally formed.

The permanent magnet60has a roughly cylindrical shape, is magnetized in the radial direction, and has mutually different magnetic poles formed on the inner circumference surface and the outer circumference surface. Also, the permanent magnet60is externally fitted and fixed on the center column part64of the yoke metal fitting58, and has mutually different magnetic poles formed on the inner circumference surface and the outer circumference surface of the circumferential groove62so as to form a magnetic field inside the circumferential groove62. A part of the inner circumference surface of the circumferential groove62is constituted by the outer circumference surface of the permanent magnet60.

Also, with the mover18, the yoke metal fitting58and the permanent magnet60are installed between the cover member22and the coil member24, and it is housed in the stator16. Also, the rod part74that extends out downward from the center column part64of the yoke metal fitting58is inserted through the upper through hole48of the bobbin42and the lower through hole26of the base member20, and projects to the inner circumference of the base member20.

Furthermore, the coil44of the coil member24is inserted into the circumferential groove62of the yoke metal fitting58, and installed in the radial direction between the yoke metal fitting58outer circumference tube part66and the permanent magnet60, and the coil44is positioned in the magnetic field formed by the permanent magnet60and the yoke metal fitting58. The coil44and the tube part of the bobbin42on which the coil44is wound are arranged separated from both the permanent magnet60and the yoke metal fitting58.

Also, the cover member22of the stator16and the yoke metal fitting58of the mover18are elastically coupled to each other by a plate spring78aand a plate spring78b. As shown inFIGS. 3 and 4, the plate spring78a/78bis a thin walled roughly round plate shaped member formed of spring steel or the like, and its outer circumference end part is equipped with a roughly round ring shaped outer circumference attachment part80a/80b, while its radial direction center is equipped with a roughly round plate shaped center attachment part82a/82b. A screw hole84a/84bthat pierces in the thickness direction is formed on the center attachment part82a/82b.

Furthermore, three spiral-shaped connection arm parts86a/86b,86a/86b,86a/86bare formed radially between the outer circumference attachment part80a/80band the center attachment part82a/82bof the plate spring78a/78b. The three connection arm parts86a/86b,86a/86b,86a/86beach extend in the radial direction while being inclined in the circumferential direction, they have roughly the same shape to each other, and are arranged at equal intervals on the circumference. More specifically, the connection arm part86a/86bhas a middle curved part87a/87bcurved so as to be concave opening towards the outer circumference and extending in roughly the circumferential direction, and both side parts of the middle curved part87a/87bcurve so as to be convex facing the outer circumference, and extend in roughly the circumferential direction. In this way, the incline angles of the connection arm parts86a/86bdiffer in the length direction, and by the connection arm parts86a/86bbeing wavy, an increase in the effective free length accompanied by dispersion of the stress and distortion is achieved.

Also, the three connection arm parts86a/86b,86a/86b,86a/86bhave one end connected to the outer circumference attachment part80a/80b, and the other end connected to the center attachment part82a/82b, and the outer circumference attachment part80a/80band the center attachment part82a/82bare integrally linked to each other by the three connection arm parts86a/86b,86a/86b,86a/86b. Also, the respective ends of the connection arm part86a/86blinked to the outer circumference attachment part80a/80band the center attachment part82a/82bare arranged at mutually different positions in the circumferential direction, and the extending direction from the outer circumference attachment part80a/80band the extending direction from the center attachment part82a/82bare mutually different. Skew of both ends of the connection arm part86a/86bis preferably ⅙ of a circumference or greater in the circumferential direction, and more preferably ¼ circumference or greater and ⅘ of a circumference or less.

Furthermore, between the three connection arm parts86a/86b,86a/86b,86a/86bon the plate spring78a/78b, slits88a/88bare respectively formed. The slits88a/88bpierce through the plate spring78a/78bin the thickness direction, and extend in the radial direction while being inclined in the circumferential direction.

Here, the plate spring78aand the plate spring78bare mutually formed with the same material and in the same shape, and as shown inFIG. 4, they overlap in the thickness direction. By doing this, the plate spring78aand the plate spring78bhave mutually equal linear expansion coefficients in the radial direction, and the heat capacities are also equal to each other. Having the shapes of the plate spring78aand the plate spring78bbe mutually the same means the dimension of each part are mutually the same, but does not include similar shapes of different sizes.

Also, the plate spring78aand the plate spring78bare matched to mutually the same position in the circumferential direction. By doing this, the plate spring78aconnection arm part86aand the plate spring78bconnection arm part86bare arranged at mutually corresponding positions, and the slit88aof the plate spring78aand the slit88bof the plate spring78bare arranged at mutually corresponding positions, and the edge parts of the plate springs78aand78broughly overlap overall.

Furthermore, an outer circumference spacer90is interposed between the overlapping surfaces of the plate spring78aand the plate spring78b. The outer circumference spacer90has a large diameter roughly round ring plate shape, is sandwiched between the plate spring78aouter circumference attachment part80aand the plate spring78bouter circumference attachment part80b, and is arranged between the outer circumference end parts of the plate springs78aand78b.

Furthermore, a center spacer92is interposed between the overlapping surfaces of the plate spring78aand the plate spring78b. The center spacer92has a small diameter roughly round ring plate shape, is sandwiched between the plate spring78acenter attachment part82aand the plate spring78bcenter attachment part82b, and is arranged so as to enclose the opening circumference edge of screw holes84aand84bof the plate springs78aand78b. The outer circumference spacer90and the center spacer92are roughly the same to each other in the thickness dimension.

In this way, the outer circumference spacer90and the center spacer92are arranged between the overlapping surfaces of the plate spring78aand the plate spring78b, and the radial direction middle part of the plate spring78aand the radial direction middle part of the plate spring78bare separated by a designated distance to each other in the thickness direction, and are arranged facing each other. In other words, the connection arm part86aof the plate spring78aand the connection arm part86bof the plate spring78bare arranged facing each other separated in the thickness direction.

Also, as shown inFIG. 1, the outer circumference attachment parts80aand80bof the plate springs78aand the plate spring78bas well as the outer circumference spacer90are sandwiched vertically between the upper base step part34of the cover member22and a ring member94fit into the cover member22, and the center attachment parts82aand82bof the plate springs78aand78bas well as the center spacer92are overlapped on the coupling projection70of the yoke metal fitting58, and are fixed to the yoke metal fitting58by a screw96screwed into screw hole72of the coupling projection70. With these, the outer circumference parts of the plate springs78aand78bare attached to the stator16, and the center parts of the plate springs78aand78bare attached to the mover18, and the stator16and the mover18are mutually linked by the plate springs78aand78b. As a result, the mover18is relatively positioned in the radial direction by the plate springs78aand78bin relation to the stator16, and by the elastic deformation in the thickness direction of the plate springs78aand78b, is displaceable vertically in the axis direction relative to the stator16.

With the electromagnetic actuator12constituted as described above, the power feed connector50is connected to an external power supply (not illustrated), and by power being fed to the coil44, current flows in the magnetic field formed by the permanent magnet60and the yoke metal fitting58, and oscillation drive force is applied based on the electromagnetic force between the stator16and the mover18. Also, by the generated oscillation drive force, the mover18is driven and displaced vertically in relation to the stator16.

Also, the mover18and the stator16of the electromagnetic actuator12are elastically coupled by a support rubber elastic body98. The support rubber elastic body98is a rubber elastic body having a roughly round ring plate shape, with the inner circumference edge part vulcanized and adhered to an inner circumference fixing member100, and the outer circumference end part vulcanized and adhered to an outer circumference fixing member102. The inner circumference fixing member100is a hard member having a roughly round cylinder shape with a bottom facing the reverse with a small diameter, and a screw hole104is formed in the radial direction center part of the upper base wall part. The outer circumference fixing member102is a hard member having a large diameter roughly round cylinder shape, with a ring shaped abutting piece106projecting to the outer circumference integrally formed on the lower edge, and a crimping piece108extending out further downward from the ring shaped abutting piece106integrally formed in part on the circumference. Also, the inner circumference end part of the support rubber elastic body98is vulcanized and adhered to the entire surface of the circumference wall part of the inner circumference fixing member100, and the outer circumference end part of the support rubber elastic body98is vulcanized and adhered to the inner circumference surface of the outer circumference fixing member102. The support rubber elastic body98of this embodiment is formed as an integrally vulcanization molded component equipped with the inner circumference fixing member100and the outer circumference fixing member102.

Also, the screw part76of the yoke metal fitting58is inserted through the screw hole104of the inner circumference fixing member100, and by screwing it in a nut110arranged below the screw hole104, the inner circumference end part of the support rubber elastic body98is fixed to the mover18. Furthermore, by the outer circumference fixing member102being fit to the circumference wall part of the base member20, the outer circumference end part of the support rubber elastic body98is attached to the stator16. By doing this, the stator16and the mover18are elastically coupled to each other by the plate springs78aand78bat the top part, and are elastically coupled to each other by the support rubber elastic body98at the bottom part.

Also, a lid member112is installed beneath the support rubber elastic body98. The lid member112has a thin walled, large diameter roughly round plate shape, and by having the outer circumference end part crimped by the crimping piece108at a plurality of locations on the circumference, it is fixed to the outer circumference fixing member102. The outer circumference end part of the support rubber elastic body98adhered to the lower surface of the ring shaped abutting piece106is interposed between the outer circumference fixing member102ring shaped abutting piece106and the lid member112, and between the overlapping surfaces of the ring shaped abutting piece106and the lid member112is sealed, so penetration of foreign matter is prevented.

With the active vibration damper10with this kind of constitution, the stator16is directly fixed to the vehicle body14, and the mover18is indirectly elastically supported on the vehicle body14via the plate springs78aand78band the support rubber elastic body98, thus being mounted on the vehicle. Specifically, as shown inFIG. 1, attachment bolts114are inserted through each bolt hole32and40of the base member20and the cover member22constituting the stator16, and by the attachment bolts114being screwed into the vehicle body14side, the stator16is fixed to the vehicle body14. Meanwhile, the mover18is elastically coupled to the stator16by the plate springs78aand78band the support rubber elastic body98, so it is supported on the vehicle body14via the stator16.

Also, the stator16is able to specify the orientation of the circumferential direction from outside using the projection direction of the base attachment pieces30,30with the base member20and the cover attachment pieces38,38with the cover member22, and the projection direction of the power feed connector50with the coil member24. By doing this, the orientation of the stator16to the vehicle body14with the circumferential direction can be easily confirmed from outside by a visual check or the like, and the stator16can be attached in a suitable orientation to the vehicle body14.

Furthermore, with the plate springs78aand78b, the orientation in the circumferential direction in relation to the stator16is set in advance to a specific orientation, and relative rotation of the circumferential direction in relation to the stator16is prevented. By doing this, even if the plate springs78aand78bcovered by the cover member22are not viewed directly, it is possible to confirm from the outside the orientation of the plate springs78aand78busing the orientation of the stator16. Therefore, as shown inFIG. 2, by attaching the stator16to the vehicle body14in a suitable orientation, it is possible to suitably set the orientation of the plate springs78aand78bin the circumferential direction in relation to the vehicle body14. As is clear from the above, with this embodiment, the direction recognition means is constituted by fixing the outer circumference attachment parts80aand80bof the plate springs78aand78bbeing fixed between the upper base step part34and the ring member94, and by the projection direction of the attachment pieces30and38and the power feed connector50with the stator16.

The orientation of the plate springs78aand78bof this embodiment to the vehicle body14in the circumference direction is set using the direction recognition means so that both ends of each of the three connection arm parts86a/86b,86a/86b,86a/86bwhich are the connecting parts to the outer circumference attachment parts80aand80band the center attachment parts82aand82bare separated with the front-back direction of the vehicle as the circumferential direction.

Specifically, with this embodiment, with the load acting in the radial direction of the plate springs78aand78b, the load of the front-back direction due to vehicle acceleration, deceleration or the like has the highest input frequency and becomes the largest. In light of that, in relation to the vehicle front-back direction which is the main load input direction and also the maximum load input direction, the orientation of the plate springs78aand78bis set so that both ends of the connection arm part86a/86bare separated in the circumferential direction. By setting the orientation in the circumferential direction of the plate springs78aand78bas described above, high frequency input of large loads in the radial direction is avoided at connection sites of both ends of the connection arm parts86a/86band the outer circumference attachment parts80aand80band the center attachment parts82aand82b, and durability is improved by dispersing the stress. The plate springs78aand78bare aligned in the circumferential direction in relation to the stator16, so by the stator16being attached to the vehicle body14, the plate springs78aand78bare arranged so as to be in a designated orientation in the circumferential direction.

More preferably, the orientation in the circumferential direction of the plate springs78aand78bis set so that the area of 1/10 of the full length from both ends of the connection arm parts86aand86bis separated with the vehicle front-back direction as the circumferential direction. By doing this, dispersion of the stress is realized even more advantageously by the deformation and displacement of the middle part of the connection arm parts86aand86b.

Also, with the plate spring78a/78bof this embodiment, both ends of each single connection arm part86a/86bare arranged at mutually different positions in the circumferential direction. Therefore, when a load is input in the radial direction, due to elastic deformation of the middle part of the connection arm part86a/86b, the stress and thus distortion transmitted to both end parts of the connection arm part86a/86bis reduced by dispersion or the like to the middle part, and the stress that acts on both end parts of the connection arm part86a/86bis more advantageously reduced, so durability is further improved.

Also, in the mounted state on the vehicle, the coil44is energized from an external power supply (not illustrated), and by the mover18doing oscillation driving on the stator16, oscillation force is applied to the vehicle body14, and vibration is offset by the oscillation force and thus reduced. Here, the stator16and the mover18are linked to each other by two plate springs78aand78boverlapping with each other. Therefore, compared to when linking with one plate spring, it is possible to set the spring constant in the thickness direction to be large without making the thickness dimensions of each plate spring78a/78blarger.

Furthermore, by spacers90and92being interposed between the plate spring78aand the plate spring78b, when the mover18undergoes oscillation driving, it is possible to prevent the plate spring78aand the plate spring78bfrom rubbing each other by elastic deformation, and the occurrence of noise, damage to the plate springs78aand78band the like are avoided. In fact, the outer circumference spacer90is installed between the outer circumference attachment parts80aand80bof the plate springs78aand78b, and the center spacer92is installed between the center attachment parts82aand82bof the plate springs78aand78b, so a large free length of the connection arm part86a/86bis ensured, and durability of the plate springs78aand78bis ensured.

Also, the plate spring78aand the plate spring78bare mutually formed with the same material and in the same shape, and they are aligned so as to have the same orientation as each other in the circumferential direction, and the radial direction swelling deformation volume and contraction deformation volume due to heating or cooling are both equal to each other. Therefore, even after deformation due to temperature changes, the connection arm part86aof the plate spring78aand the connection arm part86bof the plate spring78bhave roughly the same shape as each other, and during oscillation driving of the mover18, the elastic deformation in the thickness direction of the connection arm part86aand the connection arm part86boccurs in mutually the same manner. Therefore, the elastic deformation of the connection arm parts86aand86bis allowed smoothly without them interfering with each other, and local stress concentration is prevented, so durability is improved.

In fact, since the plate spring78aand the plate spring78bare formed with the same material and shape as each other, in addition to the linear expansion coefficients being equal to each other, the heat capacities are also equal to each other. Therefore, in relation to ambient temperature changes, the plate spring78aand the plate spring78bhave roughly the same temperature changes occur, and the deformation volumes of the plate spring78aand the plate spring78bin relation to the ambient temperature changes are roughly the same to each other, and improved durability is more advantageously obtained by dispersion of the stress.

In addition, since the plate springs78aand78bhave the same material and the same shape, it is possible to have the plate springs78aand78bbe a common part, and by reducing the number of types of parts, manufacturing is easier.

Also, the plate spring78aand the plate spring78bare aligned so as to have the same orientation in the circumferential direction. Therefore, when the mover18undergoes oscillation driving in relation to the stator16, when the plate springs78aand78bare elastically deformed in the thickness direction, the deformation volume and deformation mode of the plate springs78aand78bare roughly the same. In specific terms, when the plate spring78aand78bouter circumference attachment parts80aand80band the center attachment parts82aand82bare relatively displaced in the thickness direction, the connection arm parts86aand86bthat connect the outer circumference attachment parts80aand80band the center attachment parts82aand82bare deformed so as to be inclined in the radial direction in the vertical cross section shown inFIG. 4. Here, by the plate springs78aand78bbeing aligned in the circumferential direction, the incline angle of each site of the connection arm part86aand the incline angle of each site of the connection arm part86bare the same as each other, so the spring in the vertical direction is kept mutually the same, and it is possible to prevent a concentration of stress and thus distortion for both the connection arm parts86aand86b.

Also, by the durability of the plate springs78aand78bimproving, excellent reliability is realized with the electromagnetic actuator12and the active vibration damper10using the same.

Above, we gave a detailed description of an embodiment of the present invention, but the present invention is not limited by that specific description. For example, the specific number and shape of the connection arm part with the plate spring are not to be interpreted as being limited by the embodiment noted above.

It is also possible to use three or more plate springs overlapped. Furthermore, the plurality of plate springs overlapped can be respectively arranged at positions separated vertically, and the mover and the stator can be linked to each other at both sides top and bottom by two sets of those plate springs.

Also, for example, it is possible to form notches or holes on the plate spring and also form projections on the stator, and by the projections locking with the plate spring notches or holes in the circumferential direction, the plate spring can be aligned to the stator in the circumferential direction. By doing this, it is possible to prevent skewing of the orientation of the plate spring78aand the plate spring78bin the circumferential direction, and to effectively obtain the target durability.

It is also possible to link the mover and stator by the plate springs having the outer circumference attachment parts attached to the mover, and the center attachment parts attached to the stator.

Also, with this embodiment, the outer circumference spacer90and the center spacer92both have a continuous ring shape in the circumferential direction, but for example it is also possible for spacers extending with a length less than a half cycle in the circumferential direction to be provided partially on a plurality of locations on the circumference.

With this embodiment, we showed an example of the active vibration damper10equipped with the electromagnetic actuator12of the present invention, but for example, it is also possible to use the electromagnetic actuator of the present invention as the actuator of a fluid-filled active vibration damping device such as that shown in Japanese Patent No. JP-B-4852030. Specifically, the fluid-filled active vibration damping device has a constitution such that a first mounting member and a second mounting member are elastically coupled by a main rubber elastic body, and a pressure-receiving chamber is formed a portion of whose wall is constituted by the main rubber elastic body, and non-compressible fluid or liquid is sealed in that pressure-receiving chamber. Furthermore, another portion of the wall of the pressure-receiving chamber is constituted by an oscillation member, and using the electromagnetic actuator of the present invention as the actuator that does oscillation driving of the oscillation member, the stator of the electromagnetic actuator is attached to the second mounting member, and the mover is attached to the oscillation member. Also, by the oscillation member being driven by the electromagnetic actuator, active oscillation force is applied to the pressure-receiving chamber, and it is possible to offset and reduce the input vibration.

Also, with this embodiment, an example was shown with the vehicle body14as the member subject to vibration damping to which the active vibration damper10is attached, but the member subject to vibration damping is not particularly limited.