JP4736844B2 - Unsprung dynamic damper and suspension device - Google Patents

Description

  The present invention relates to an unsprung dynamic damper employed in a vehicle suspension device, and a suspension device provided with the unsprung dynamic damper.

As described in the following patent document, it has been studied to provide an unsprung dynamic damper using an inertial mass body (hereinafter sometimes referred to as “mass”) in a suspension device. The unsprung dynamic damper has a function of absorbing vibration of an unsprung resonance frequency or a frequency near the unsprung resonance frequency and effectively suppressing transmission of the vibration to the sprung member.
Japanese Patent No. 2503258 JP-A-6-143966

  The unsprung dynamic damper is suitable for constructing an active suspension based on the Skyhook theory because of the above functions, but it has various problems such as spatial constraints to arrange it. It has not been put into practical use yet. The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a highly practical unsprung dynamic damper, and also to provide a highly practical suspension device in which the unsprung dynamic damper is disposed. Is an issue.

In order to solve the above problems, the unsprung dynamic damper of the present invention includes: (a) an inertial mass body that is movable in the vertical direction with respect to the unsprung member; and (b) the inertial mass body and the unsprung member. A male screw portion fixedly provided on one of the members and a female screw portion fixedly provided on the other of the inertia mass body and the unsprung member and screwed with the male screw portion. A motion conversion mechanism configured to include a screw mechanism having an axis extending in the vertical direction, and converting the vertical motion of the inertial mass body into a rotational motion of the inertial mass body; and (c) the inertial mass. And an elastic support that elastically supports the body. The suspension device according to the present invention includes a spring that elastically supports the unsprung member and the sprung member, an electromagnetic shock absorber that attenuates relative motion between the unsprung member and the sprung member, and the spring. A lower dynamic damper is included.

  The unsprung dynamic damper of the present invention is configured so that a mass that has been conventionally moved only in the vertical direction with respect to the unsprung member functions as a rotating mass, and has an inertial force with respect to the rotational motion of the mass. Be available. Therefore, according to the present invention, the mass can be made compact, and the unsprung dynamic damper can be miniaturized, and can be easily disposed in the suspension device. That is, a highly practical unsprung dynamic damper is realized. The suspension device of the present invention is a so-called electromagnetic suspension device, and can be suitably used in an active suspension system. If an unsprung dynamic damper is employed in this electromagnetic suspension device, a high-performance suspension system. Is realized. The suspension device of the present invention is provided with the above-described dynamic damper. Since the dynamic damper can be easily disposed in the device, the suspension device of the present invention facilitates a high-performance suspension system. It becomes possible to build in. That is, according to the present invention, the practicality of the electromagnetic suspension device is enhanced.

Aspects of the Invention

  In the following, some aspects of the invention that can be claimed in the present application (hereinafter sometimes referred to as “claimable invention”) will be exemplified and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is merely for the purpose of facilitating the understanding of the claimable inventions, and is not intended to limit the combinations of the constituent elements constituting those inventions to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. In addition, an aspect in which some constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention.

The following item (1) is a term indicating a precondition of the claimable invention, and the item below the item (2) that directly or indirectly cites the item (1) is an aspect of the claimable invention. It becomes the term which shows. Incidentally, in each of the following items, the combination of the items (1), (2), and (3) corresponds to claim 1, and the technical features of item (4) are added to claim 1. The present invention is limited to claim 2, the claim 2 is limited by the technical feature of the item (5), the claim 3 is limited to the technical feature of the item (6), and the claim 2 or 3 is limited by the technical feature of the item (6). What has been added corresponds to claim 4, and claim 4 to which restriction by the technical features of (9) is added corresponds to claim 5. Further, the item (21) corresponds to the sixth aspect.

  (1) An unsprung dynamic damper that includes an inertial mass that is movable in the vertical direction relative to the unsprung member and an elastic support that elastically supports the inertial mass, and that absorbs unsprung vibration. .

  The aspect of this section is an aspect in which the constituent elements that are the premise of the claimable invention are listed. The “unsprung member” in this section is a component of the suspension device and is disposed on the wheel side with the suspension spring interposed therebetween, and means a member that moves up and down as the wheel moves up and down. Specifically, for example, a member connected to a suspension arm, a suspension arm of a shock absorber, or the like is applicable. On the other hand, the concept of “sprung member” is a component of a suspension device or a vehicle body that is arranged on the vehicle body side with the suspension spring interposed therebetween, and that moves up and down as the vehicle body moves up and down. means. Specifically, a part of the vehicle body to which the components of the suspension device are attached, a member connected to a part of the vehicle body of the shock absorber, and the like are applicable.

  The “inertial mass” is a so-called “mass”, “inertial mass” or the like, and the inertial force resulting from the mass of the “inertial mass” is vibration absorption by the dynamic damper (it can also be considered as absorption of vibration energy). It means what is used for. The “vertical direction” in which the inertial mass body (hereinafter sometimes referred to as “mass”) is allowed to move with respect to the unsprung member is, for example, the vertical movement of the wheel, the rotation direction of the suspension arm, or the like. This is a concept that should be interpreted as a vertical direction according to the above, that is, a generally vertical direction, and is not a concept that is interpreted only in a vertical direction.

  The “elastic support” can be considered to support, for example, a mass by exerting an elastic force for maintaining the mass in a neutral position. The neutral position here can be considered, for example, a position where the elastically supported mass is located in a state where the vehicle is stationary on a horizontal road surface. Note that the neutral position is a concept including the rotational position of the mass when the mass is a rotational mass described later. That is, the elastic support is not limited to the one that applies elastic force in the vertical direction to the mass, and may be one that applies elastic force in the rotational direction when it is a rotating mass.

  The elastic support member may be any member that is substantially made of an elastic force such as a spring or rubber. It can be configured by a spring or the like to be an elastic support having a relatively small damping action, or can be configured by rubber or the like to be an elastic support having a relatively large damping action. Incidentally, when an elastic support body having a relatively large damping action is employed, it is possible to effectively absorb unsprung vibration having a certain frequency width without separately providing a damping force generation device described later. In addition, the aspect of this term is not limited to an aspect in which only one elastic support is employed. For example, a plurality of elastic supports may be employed as in an aspect in which a mass is sandwiched between two springs. It is.

  (2) The unsprung dynamic damper according to (1), wherein the unsprung dynamic damper includes a motion conversion mechanism that converts the vertical motion of the inertial mass body into a rotational motion of the inertial mass body.

  In short, the aspect described in this section is an aspect in which the inertial mass body functions as a so-called rotating mass. In the conventional unsprung dynamic damper, the mass is allowed to move only in the vertical direction, so that the inertia force in the vertical direction is exhibited. On the other hand, in the aspect of this section, the motion conversion mechanism is employed, and in addition to the vertical motion, or instead of the vertical motion, the mass is rotated and the inertial force with respect to the rotation is obtained. Also configured to use. With this configuration, the inertia mass body functions as an efficient mass. Thus, the mass can be reduced, and a compact unsprung dynamic damper can be realized.

  The structure of the “motion conversion mechanism” is not particularly limited. For example, it is possible to employ a screw mechanism or the like as will be described later. In addition, the degree to which the vertical motion is converted by the motion conversion mechanism can be arbitrarily set according to the design specifications of the dynamic damper.

(3) The motion conversion mechanism is
A male screw portion fixedly provided in one of the inertial mass body and the unsprung member in the vertical direction, and a fixed screw member provided on the other of the inertial mass body and the unsprung member and screwed into the male screw portion. The unsprung dynamic damper according to item (2), including a screw mechanism including a female screw portion, and an axis of the male screw portion and the female screw portion extending in the vertical direction.

  The mode of this section is a mode that employs a motion conversion mechanism using a screw mechanism. According to the aspect of this section, the rotating mass body can easily function as a rotating mass. Further, when a screw mechanism is employed, it is possible to adjust the degree of functioning as a rotating mass, that is, the degree of conversion of vertical motion into rotational motion by adjusting the lead angle of the screw. From the viewpoint of minimizing the influence of friction in the screw mechanism, that is, the damping action by the screw mechanism, it is desirable to employ a ball screw mechanism or the like.

  (4) The unsprung dynamic damper according to any one of (1) to (3), wherein the unsprung dynamic damper includes a damping force generating device that generates a damping force with respect to the motion of the inertial mass body.

  In the unsprung dynamic damper, it is desirable to apply a certain amount of damping force to the mass motion in order to widen the frequency range of vibration that can be substantially absorbed. According to the aspect of this section, for example, even when an elastic support body, a motion conversion mechanism, or the like having a small damping action is employed, it is possible to make the frequency range capable of absorbing vibration relatively large.

  The “damping force generating device” in the aspect of this section can have a structure that applies a damping force to the vertical movement of the mass. Further, in the case where the inertial mass body functions as a rotating mass, as will be described later, it is possible to have a structure that applies a damping force to the rotation of the mass.

  Further, the “damping force generator” in the aspect of this section is not particularly limited in principle for generating the damping force. It can be configured to generate a damping force depending on an electromagnetic force generated by an electromagnetic actuator described later, and, for example, two moving bodies (one of which is a mass) that moves relative to each other as the mass moves. It is possible to adopt various configurations, such as a configuration that generates a damping force that depends on the frictional force between them (including the case of the above) and a configuration that generates a damping force that depends on the resistance of the fluid. Incidentally, in the case of a configuration that generates a damping force that depends on the resistance of the fluid, for example, a moving body that moves in the fluid in accordance with the movement of the mass is provided, and the resistance when the moving body advances by pushing away the fluid. In addition, two relative moving bodies that face each other and move according to the movement of the mass are provided, and the fluid interposed between the moving bodies is provided. A structure that generates a damping force due to shear resistance, or a moving body that divides the inside of a container containing a fluid into two chambers and moves in accordance with the movement of the mass to change the relative volume of the two chambers. Furthermore, it is possible to provide a flow path for moving the fluid between the two chambers as the moving body moves, and to generate a damping force due to the fluid passage resistance in the flow path. A.

  (5) The unsprung dynamic damper includes a motion conversion mechanism that converts the vertical motion of the inertial mass body into the rotational motion of the inertial mass body, and the damping force generator includes the rotational motion of the inertial mass body. The unsprung dynamic damper according to item (4), which generates a damping force against

  The aspect described in this section is an aspect in which when the inertial mass body is caused to function as a rotating mass, a damping force is applied to the rotation of the inertial mass body. Depending on the configuration of the motion conversion mechanism, the peripheral speed of the rotating mass can be increased compared to the speed of the vertical motion, and in such a case, a damping force can be generated efficiently.

(6) The damping force generator is
An electromagnetic actuator having a stator and a mover opposed to the stator and generating an electromagnetic force acting between the stator and the mover moves relative to the stator as the inertial mass body moves. The unsprung dynamic according to (4) or (5) is configured to generate a damping force with respect to the motion of the inertial mass body based on the electromagnetic force generated by the electromagnetic actuator. damper.

  The “electromagnetic actuator” referred to in this section is a concept including an electromagnetic motor, a generator, and the like. According to the electromagnetic actuator, it is possible to easily generate an appropriate damping force by controlling the operation. The “stator” and “mover” that are components of the electromagnetic actuator are called a stator and a rotor (or mover), respectively. For example, one of them includes a permanent magnet, and the other May be configured to include an armature having a coil or the like. The electromagnetic actuator may be a rotary electromagnetic actuator or a linear motion electromagnetic actuator (for example, a linear motor).

  In this section, “relying on the electromagnetic force generated by the electromagnetic actuator to generate a damping force for the motion of the inertial mass body” specifically means, for example, that the electromagnetic actuator is an electromagnetic motor. In some cases, the power may be supplied from a power source connected thereto to generate a damping force based on the driving force of the electromagnetic motor, or the generator or the electromagnetic motor. In the above, a mode may be adopted in which a damping force based on an electromotive force generated by operating these movable elements is generated. In the latter case, the electromagnetic actuator can be connected to a power source via an inverter or the like, and the generated electromotive force can be regenerated to the power source, and each phase of the electromagnetic actuator (for example, the terminal of each phase) can be connected. It is also possible to connect them directly or via a resistor so that the electromotive force is consumed by resistance.

(7) The unsprung dynamic damper includes a motion conversion mechanism that converts the vertical motion of the inertial mass body into the rotational motion of the inertial mass body,
The damping force generation device is configured to include a rotary electromagnetic actuator in which the mover is a rotor, and generates a damping force for the rotational motion of the inertial mass body (6) The unsprung dynamic damper as described in the item.

  The mode described in this section is a mode in which an inertial mass body functions as a rotating mass and a damping force is applied to the rotation by an electromagnetic actuator. According to this section, it is possible to enjoy both the advantages of functioning as a rotating mass and the advantages of employing an electromagnetic actuator.

  (8) The unsprung dynamic damper according to (6) or (7), wherein the damping force generator is capable of changing a damping force generated by controlling the electromagnetic actuator.

  The aspect described in this section is an aspect in which the electromagnetic actuator is controlled by, for example, an inverter, and the magnitude of the generated damping force can be adjusted. Since the electromagnetic actuator has good controllability, according to the aspect of this section, it is possible to apply a damping force having an appropriately set magnitude.

  (9) The electromagnetic actuator functions as a generator, and the damping force generator is configured to regenerate an electromotive force generated in the electromagnetic actuator due to the movement of the inertial mass body. Or the unsprung dynamic damper according to any one of (8).

  According to the aspect of this section, a vehicle with high energy efficiency can be constructed. In particular, when the suspension system includes an electromagnetic shock absorber, which will be described later, the energy efficient system is obtained. For example, when the system is such that the electromagnetic actuator is controlled by an inverter or the like, the aspect of this section is realized, and in that case, the electromotive force can be easily regenerated.

 (21) A spring that elastically supports the unsprung member and the sprung member, an electromagnetic shock absorber that attenuates relative motion between the unsprung member and the sprung member, and items (1) to (8) A suspension device comprising the unsprung dynamic damper according to any one of the items.

  The mode of this section is a mode in which the dynamic damper of each of the above modes is employed in a so-called electromagnetic suspension system. `` Electromagnetic shock absorber '' is a damper device that exhibits a damping force by the electromagnetic force of an electromagnetic actuator, unlike a shock absorber that uses fluid resistance that is generally adopted, and this electromagnetic shock absorber is, for example, There is a possibility that a system having good vibration absorption characteristics can be realized by active suspension control or the like based on the skyhook theory, which is expected to be put to practical use. However, at present, there is a problem that the control of the electromagnetic shock absorber cannot satisfactorily follow the vibration in the unsprung resonance frequency or in the vicinity of the frequency range. An unsprung dynamic damper is suitable as a means for solving this problem.

  On the other hand, when a dynamic damper is provided in the suspension device, if the dynamic damper is relatively large, there is a restriction due to a spatial space in which the dynamic damper is disposed. This restriction is one factor that hinders the practical use of electromagnetic suspension systems. The unsprung dynamic damper having the above-described configuration, more specifically, the dynamic damper having the configuration in which the inertia mass body functions as a rotating mass is relatively compact, and the dynamic damper is not easily limited by the installation space. It will be a thing. From this point of view, according to an aspect that employs a dynamic damper that uses a rotating mass, a highly practical suspension device can be constructed.

In addition, since the electromagnetic shock absorber constituting the electromagnetic suspension system is configured to include an electromagnetic actuator, in view of comprehensive control of the shock absorber and the dynamic damper, the unsprung dynamic damper is also electromagnetic. It is desirable to include a type actuator. Therefore, according to the aspect that employs the unsprung dynamic damper provided with the electromagnetic actuator, a suspension device that is advantageous in terms of control is realized. In addition, when using a dynamic damper equipped with an electromagnetic actuator, if the dynamic damper is configured to regenerate the electromotive force generated in the electromagnetic actuator, the electric power regenerated from the electromagnetic actuator is converted to the electromagnetic type of the shock absorber. It can be used as at least part of the power supplied to the actuator. Therefore, according to the aspect that employs the dynamic damper configured to be regenerative, a suspension device that is excellent in energy efficiency is realized.

  The structure of the electromagnetic shock absorber in this section is not particularly limited. In the suspension device of this embodiment, various electromagnetic shock absorbers having a known structure can be widely used. it can.

  Hereinafter, embodiments of the claimable invention will be described in detail with reference to the drawings. In addition to the following examples, the claimable invention is implemented in various modes including various modifications and improvements based on the knowledge of those skilled in the art, including the mode described in the above [Mode of Invention]. can do.

<Configuration of suspension device>
FIG. 1 shows a vehicle suspension apparatus 10 of the embodiment. The suspension device 10 is a device that constitutes an independent suspension system, and is provided for each of the front, rear, left, and right wheels. The suspension device 10 is provided on a part of a vehicle body (upper part of a tire housing) and has a mount portion 12 that functions as a sprung member and a suspension lower arm that functions as an unsprung member while holding a wheel (hereinafter referred to as “lower arm”). When the electromagnetic shock absorber 16 is connected to the coil 14, the coil spring 18 is a suspension spring, and the unsprung dynamic damper 20 (hereinafter simply referred to as “dynamic damper 20”) disposed on the lower arm 14. Is included).

  The shock absorber 16 includes an outer tube 30 and an inner tube 32 that is fitted into the outer tube 30 and protrudes upward from the upper end portion of the outer tube 30. The outer tube 30 includes an upper tube 34 fitted into the inner tube 32, a lower tube 36 connected to the lower end of the upper tube 34, and an attachment member 38 joined to the lower end of the lower tube 36. The attachment member 38 is connected to the lower arm 14 by a connection pin 40. The inner tube 32 has a flange portion 42 at its upper end, and is connected to the mount portion 12 at the flange portion 42. The upper tube 34 of the outer tube 30 has a direction in which the axis of the shock absorber 16 extends on the inner wall surface (hereinafter, the axis is referred to as “absorber axis”, and the direction in which the axis extends may be referred to as “axis direction”). A pair of guide grooves 44 are provided so as to extend to each other, and each of the pair of keys 46 attached to the lower end portion of the inner tube 32 is fitted in each of the guide grooves 44. The outer tube 30 and the inner tube 32 cannot be relatively rotated by the guide groove 44 and the key 46, and are relatively movable in the axial direction. Incidentally, a seal 48 is attached to the upper end portion of the upper tube 34 of the outer tube 30 to prevent entry of dust, mud and the like from the outside.

  The shock absorber 16 includes a ball screw mechanism including a screw rod 50 in which a thread groove is formed, a nut 52 that holds a bearing ball and is screwed with the screw rod 50, and an electromagnetic actuator. As an electromagnetic motor 54 (hereinafter sometimes simply referred to as “motor 54”). The motor 54 is fixedly accommodated in the motor case 56, and the flange portion of the motor case 56 is fixed to the upper surface side of the mount portion 12. The flange portion 42 of the inner tube 32 is fixed to the flange portion of the motor case 56, and the inner tube 32 is connected to the mount portion 12 via the motor case 56. A motor shaft 58 that is a rotation shaft of the motor 54 is integrally connected to the upper end portion of the screw rod 50. That is, the screw rod 50 is arranged in the inner tube 32 in a state where the motor shaft 58 is extended, and is configured to be rotated by the motor 54. On the other hand, the nut 52 is fixedly supported by the upper end part of the nut support cylinder 60 which the outer tube 30 has in the state screwed with the screw rod 50. The outer tube 30 is provided with an annular lower retainer 70 on the outer periphery thereof, and an annular upper retainer provided via the lower retainer 70 and an anti-vibration rubber 72 attached to the lower surface side of the mount portion 12. The coil spring 18 is supported by the retainer 74 in a sandwiched state.

  With the above-described structure, when the vehicle body and the wheel approach or separate from each other, that is, when the sprung member and the unsprung member move relative to each other in the vertical direction, the outer tube 30 and the inner tube 32 are relatively The screw rod 50 and the nut 52 move relative to each other in the axial direction along with the relative movement, and the screw rod 50 rotates with respect to the nut 52. The motor 54 can apply a rotational torque to the screw rod 50. By optimizing the direction and the magnitude of the rotational torque, the motor 54 can control the relative motion of the sprung member and the unsprung member. It is possible to generate an appropriate resistance force in the blocking direction. This resistance force becomes a damping force for the relative motion, and the shock absorber 16 has a function of generating the damping force. The shock absorber 16 also has a function of actively moving the outer tube 30 and the inner tube 32 in the axial direction by the driving force of the motor 54. With this function, for example, the roll of the vehicle body during turning, the pitch of the vehicle body during braking, and the like can be effectively suppressed, and so-called vehicle height adjustment can also be performed.

  As shown in FIG. 2, the dynamic damper 20 includes a housing 88 having a housing cylinder 80, a lower lid 84, and an upper lid 86, which are fixedly joined to each other. 84 is fastened to the lower arm 14 by the fastening bolt 90, and is fixed to the lower arm 14 which is an unsprung member. A boss 91 is erected on the lower lid 84, and a screw rod 94 whose lower end is fixedly held by the boss 91 and whose upper end is formed with a male screw is fastened to the upper lid 86 by a nut 92. It is fixedly provided inside the housing 88. The threaded rod 94 is arranged in such a posture that its axis is generally parallel to the absorber axis. The threaded rod 94 is formed with a thread groove, and a weight 96 is threadedly engaged with the threaded groove. The weight 96 is generally formed on a cylinder and functions as an inertial mass body, that is, a mass. In the screw hole 98 provided in the center and formed with a screw groove, the weight 96 is connected to the screw rod 94 via the bearing ball 100. It is screwed together. That is, the dynamic damper 20 has a ball screw mechanism 102 including a screw rod 94 that functions as a male screw portion, a screw hole portion 98 of a weight 96 that functions as a female screw portion, and a bearing ball 100. Yes.

  On the other hand, an inner cylinder member 110 is fixedly fitted to the housing cylinder 80 inside the housing cylinder 80, and the inner cylinder member 110 is fixed to a case main body 112 having a generally bottomed cylindrical shape and an upper end thereof. The weight case 116 including the lid 114 is held so as to be movable in the vertical direction, that is, generally in the axial direction, and non-rotatable. Specifically, the outer periphery of the weight case 116 is provided with ball holding grooves 118 formed so as to extend in the vertical direction at each of eight equally spaced positions in the circumferential direction. The balls 120 are held so that they circulate through the respective ball holding grooves 118. On the other hand, the inner cylinder member 110 fitted in the housing 88 is provided with a spline groove 122 at a position facing each of the ball holding grooves 118 so that the bearing ball 120 is fitted into the spline groove 122. Has been. That is, the ball spline mechanism 124 is configured including the spline groove 122, the ball holding groove 118, the bearing ball 120, and the like, and the weight case 116 is held in the housing 88 so as not to be rotatable and movable in the vertical direction. -ing

  The weight case 116 accommodates the weight 96 and is rotatably held by the lid body 114 and the bottom portion of the case main body 112 through the thrust bearings 128 and 130. Further, a coil spring 132 (a compression coil spring) as an elastic support is provided between the lower surface of the weight case 116 and the lower lid 84 of the housing 88, and the upper surface of the weight case 116 and the upper lid 86 of the housing 88. The coil spring 134 as an elastic support member is interposed between the weight case 116 and the weight 96, and the weight case 116, that is, the weight 96 is attached to the housing 88 by the coil springs 132 and 134, that is, The structure is elastically supported by the unsprung member.

  With such a structure, when the lower arm 14 vibrates up and down, the weight 96 moves up and down along with the vibration, and the ball screw mechanism 102 functions as a motion conversion mechanism. Will rotate. That is, the weight 96, which is an inertial mass body, has a structure that functions as a rotating mass.

  A plurality of permanent magnets 140 are attached to the outer periphery of the weight 96, while a plurality of coils 142 are provided on the inner periphery of the weight case 116 so as to face the plurality of permanent magnets 140. Is attached. The outer periphery of the permanent magnet 140 and the weight 96 that holds them fixedly functions as a rotor, and the coil 142 functions as a stator. The motor has an electromagnetic motor 144 (a DC brushless motor, which may be abbreviated as “motor 144” hereinafter) as a motive. A rotation sensor 146 for detecting the rotation position (rotation angle) of the weight 96 is provided in the vicinity of the center of the case main body 112 of the weight case 116, whereby the rotation position of the weight 96, that is, the motor. The rotational position 144 (rotor position of the rotor) is detected. Incidentally, the detection value of the rotation sensor 146 is used for switching the energized phase according to the rotation position of the motor 144.

  As the weight 96 rotates, an electromotive force is generated in the motor 144 due to the electromagnetic force between the permanent magnet 140 and the coil 142, and the resistance force depending on the electromotive force is applied to the rotating motion of the weight 96. Will be generated. Further, when electric power from the power source is supplied to the motor 144, the motor 144 exhibits a rotational driving force, and a resistance force depending on the driving force is generated with respect to the rotational motion of the weight 96. Since such a resistance force acts as a damping force with respect to the rotational motion of the weight 96, that is, the motor 144 functions as a damping force generator that generates a damping force with respect to the weight motion as the inertial mass body. It has been done.

<Control of suspension system>
Since the electromagnetic shock absorber can easily generate a damping force having a magnitude depending on the vertical movement speed of the vehicle body on the spring, it is suitable for a suspension device based on the so-called skyhook theory. The basic suspension model based on skyhook theory is such as shown in FIG. 3 (a), in this model, consider the tire as a spring S _T, together with the wheel is supported by the spring S _T, wheels and the vehicle body is supported on each other by a suspension spring S _S, the damper apparatuses D ₁ has a configuration to generate a damping force of a magnitude depends on the vertical movement speed of the vehicle body. However, in the case of such a model can not be effectively damping the vibration of the wheel is under spring, for example, it suffers from a problem that can not be be kept good grounding of the wheel. Therefore, as shown in FIG. 3 (b), a model in which a separate damper device D ₂ between the wheel and the vehicle body can be envisaged. However, when a normal electromagnetic shock absorber is used and the damping device D ₁ and the damper device D ₂ are controlled to generate a damping force to be generated in order to absorb the unsprung vibration according to this model, the unsprung state is required. The control of the electromagnetic motor does not follow the high-frequency wheel vibration at or near the resonance frequency, and as a result, unsprung vibration is transmitted to the vehicle body.

In view of the above, a model as shown in FIG. 3C can be considered. In this model, the mass M is supported by the spring S _M under the spring, and a damper device D ₃ for providing a damping force for the operation of the mass M is provided, and a so-called unsprung dynamic damper is added. . According to this model, the effect of the unsprung dynamic damper, effectively it becomes possible to absorb the relatively high frequency of the unsprung vibration, as shown in FIG. 4, for example, the unsprung resonance frequency omega ₁ Transmission of relatively high-frequency unsprung vibration having a near frequency or higher frequency to the vehicle body is suppressed, and the grounding performance of the wheel is improved. The suspension device 10 includes an electromagnetic shock absorber 16 and a dynamic damper 20 that functions as an unsprung dynamic damper, and can realize a suspension device based on the Skyhook theory in an almost ideal form. It has become.

  The suspension apparatus 10 is controlled by a suspension apparatus control unit (ECU) 150 as shown in FIG. More specifically, the motor 54 of the shock absorber 16 and the motor 144 of the dynamic damper 20 are connected to the battery 156 via inverters 152 and 154 as drive circuits, respectively, and the ECU 150 sends control signals to the inverters 152 and 154. Then, the inverters 152 and 154 execute operation control of the respective motors 54 and 144 according to these control signals.

A sprung acceleration sensor 160 is provided in the vicinity of the mount portion 12 of the vehicle body, and the motor 54 is controlled based on the detection value of the sprung acceleration sensor 160. Specifically, the ECU 150 calculates the vertical movement speed V _U of the mount 12 of the vehicle body based on the detection signal, and the calculated speed V _U and the attenuation set according to the Skyhook theory. Based on the coefficient C _A , the following formula F _A = V _U · C _A
Accordingly, the damping force F _A to be generated by the shock absorber 16 is calculated, and the motor 54 is controlled so as to obtain the rotational force of the motor 54 corresponding to the damping force F _A.

Similarly, the lower arm 14 is provided with an unsprung acceleration sensor 162, and the control of the motor 144 is performed based on the detection value of the unsprung acceleration sensor 162. Specifically, the ECU 150 calculates the moving speed V _S in the vertical direction of the lower arm 14 based on the detection signal, and the calculated speed V _S and the above-described relatively high-frequency unsprung vibration are effective. Based on the damping coefficient C _D that is set so as to be capable of being absorbed, the following formula F _D = V _S · C _D
Accordingly calculates the damping force F _D to the dynamic damper 20 generates, as the rotational force of the motor 144 corresponding to the damping force F _D is obtained, the motor 144 is controlled.

The motor 144 is mainly controlled to function as a generator, and the electromotive force generated by the rotation of the weight 96 is regenerated in the battery 156. The damping force characteristic of the motor 144, more specifically, the rotational speed of the weight 96, that is, the torque Tq of the motor 144 with respect to the rotational speed V _N of the rotor of the motor 144 (the torque acting in the direction opposite to the rotational direction of the rotor) 5 is a characteristic as shown in FIG. 5, and the motor 144 is operated in a regenerative braking region which is a region (a shaded region in FIG. 5) located below the short-circuit characteristic line. Here, the short-circuit characteristic line is a characteristic line indicating the torque Tq exerted by the motor 144 based on the electromotive force generated when the phases of the motor 144 are short-circuited with each other. The region is a so-called reverse braking region. That is, the torque Tq necessary to obtain the damping force F _D is present below the short-circuit characteristic line with respect to the range of the rotational speed V _N where the weight 96 is rotated in the normal unsprung vibration. The motor having the characteristics is employed as the motor 144 provided in the dynamic damper 20. On the other hand, the motor 54 provided in the shock absorber 16 is a motor having such characteristics that it can be operated even in the reverse braking region. Therefore, in the present suspension device 10, the power regenerated from the motor 144 of the dynamic damper 20 is used as a part of the power supplied to the motor 54 of the shock absorber 16.

<Another dynamic damper>
FIG. 6 shows another unsprung dynamic damper that can be employed in the suspension device 10. The dynamic damper 180 shown in the figure employs a damping force generator having a structure that generates a damping force based on fluid resistance, whereas the previous dynamic damper 20 includes an electromagnetic motor 144 as a damping force generator. ing. Since the dynamic damper 180 has the same configuration as that of the previous dynamic damper 20 except for the damping force generator, the description of the dynamic damper 180 will be made mainly on the different parts of the dynamic damper 180 and the constituent elements. Explanations of components having similar functions will be omitted or simplified by using the same reference numerals.

  In the dynamic damper 180, the lid 186 that covers the case main body 184 of the weight case 182 includes an upper member 188 and a lower member 190, and a structure that backs up the thrust bearing 128 at the lower end surface of the lower member 190. It is said that. A generally donut-shaped space exists between the upper member 188 and the lower member 190, and a highly viscous fluid described later is accommodated in the space. That is, the lid body 186 has the fluid chamber 192. On the other hand, a support tube 198 is fixedly erected on the upper portion of the weight 196 functioning as an inertial mass body with a threaded rod 94 inserted therethrough, and a disc-shaped rotating disk is provided on the outer periphery of the support tube 198. 200 is supported so that relative rotation is impossible. The rotating disk 200 is housed in the fluid chamber 192 described above, and rotates around the axis of the screw rod 94 in the fluid chamber 192 as the weight 196 rotates. In the fluid chamber 192, a highly viscous fluid is accommodated, and between the outer peripheral surface of the support tube 198 and the inner surface of the hole provided in the center of the upper member 188 and the lower member 190 constituting the lid 186, Seals 202 and 204 are interposed so that the highly viscous fluid does not leak due to their relative sliding.

  When the rotating disk 200 rotates with the rotation of the weight 196, the rotating disk 200 receives resistance from the highly viscous fluid with respect to the rotation. This resistance functions as a damping force for the rotational motion of the weight 196, that is, a damping force for the motion of the inertial mass body. The dynamic damper 180 employs a damping force generator having the above structure instead of an electromagnetic motor.

It is front sectional drawing of the suspension apparatus for vehicles of an Example. FIG. 2 is a front cross-sectional view of a dynamic damper employed in the vehicle suspension device of FIG. 1. It is a conceptual diagram which shows the suspension model based on the skyhook theory. FIG. 4 is a graph showing a difference in vibration transmission characteristics and wheel grounding characteristics with and without an unsprung dynamic damper in the model shown in FIG. 3. It is a chart which shows the characteristic of the electromagnetic motor with which the dynamic damper of FIG. 2 is provided. FIG. 5 is a front sectional view of another dynamic damper that can be employed in the vehicle suspension device of FIG. 1.

Explanation of symbols

  10: Vehicle suspension device 12: Mount portion (sprung member) 14: Suspension lower arm (unsprung member) 16: Shock absorber (electromagnetic shock absorber) 18: Coil spring (suspension spring) 20: Dynamic damper (unsprung dynamic) 30): outer tube 32: inner tube 50: screw rod 52: nut 54: electromagnetic motor 96: weight (inertial mass body) 102: ball screw mechanism (motion conversion mechanism) 132, 134: coil spring (elastic support) 140: Permanent magnet (mover, rotor) 142: Coil (stator) 106: Electromagnetic motor (electromagnetic actuator, damping force generator) 180: Dynamic damper (unsprung dynamic damper) 1 2: the fluid chamber (damping force generating device) 196: Weight (inertial mass) 200: rotary disk (damping force generating device)

Claims (6)

An inertial mass that is movable in the vertical direction with respect to the unsprung member;
A male screw portion fixedly provided on one of the inertial mass body and the unsprung member, and a female screw portion fixedly provided on the other of the inertial mass body and the unsprung member and screwed with the male screw portion. And includes a screw mechanism in which the axial lines of the male screw portion and the female screw portion are arranged to extend in the vertical direction, and the vertical motion of the inertial mass body is converted into the rotational motion of the inertial mass body. A motion conversion mechanism;
An unsprung dynamic damper comprising an elastic support for elastically supporting the inertia mass body and absorbing unsprung vibration.   The unsprung dynamic damper according to claim 1, further comprising a damping force generator that generates a damping force with respect to the motion of the inertial mass body.   The unsprung dynamic damper according to claim 2, wherein the damping force generating device generates a damping force with respect to the rotational motion of the inertial mass body. The damping force generator is
An electromagnetic actuator having a stator and a mover opposed to the stator and generating an electromagnetic force acting between the stator and the mover moves relative to the stator as the inertial mass body moves. 4. The unsprung dynamic damper according to claim 2, wherein the unsprung dynamic damper is configured to generate a damping force with respect to the motion of the inertial mass body based on an electromagnetic force generated by the electromagnetic actuator. 5.   5. The electromagnetic actuator according to claim 4, wherein the electromagnetic actuator functions as a generator, and the damping force generator is configured to regenerate an electromotive force generated in the electromagnetic actuator due to the movement of the inertial mass body. Unsprung dynamic damper.   6. A spring that elastically supports the unsprung member and the sprung member, an electromagnetic shock absorber that attenuates relative movement between the unsprung member and the sprung member, and any one of claims 1 to 5. A suspension device comprising the unsprung dynamic damper described above.

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