JP2009216210A - Damping force variable damper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a damping force variable damper that is compact and easy to assemble in a variable damping force damper using MRF.
SOLUTION: An inner yoke is formed by combining at least two parts in the axial direction, and an O-ring is interposed between the two parts or between one of the two parts and a rod or a cylindrical extension part of a resin mold of a coil. Thus, the piston rod inner hole for drawing out the lead wire of the coil is preferably sealed against the magnetic fluid in the cylinder. Thereby, a simple seal can be ensured by simply assembling the components of the piston, and assembly can be performed easily and at low cost.
[Selection] Figure 3

Description

  The present invention relates to a telescopic variable damping force damper that constitutes a suspension for an automobile, and more particularly to a variable damping force variable damper that is compact and easy to assemble.

  2. Description of the Related Art In recent years, various types of damping force variable dampers capable of variable damping force control have been developed for cylindrical dampers used in automobile suspensions in order to improve riding comfort and steering stability. As the damping force variable damper, a mechanical type in which a rotary valve that changes the orifice area is provided on the piston and this rotary valve is driven to rotate by an actuator has been the mainstream, but simplification of the configuration and improvement of responsiveness etc. In order to achieve this, there has been a technology in which a magnetorheological fluid is used as a working fluid and the viscosity of the magnetorheological fluid is controlled by a magnetorheological valve formed integrally with a piston (see Patent Document 1).

In the damping force variable damper of Patent Document 1, the piston is a cylindrical inner yoke having a coil wound around its outer periphery, a pair of end plates disposed at both ends of the inner yoke, and a cylindrical shape that houses the inner yoke and both end plates. The outer yoke is mainly composed of. Both the inner yoke and the outer yoke are made of a ferromagnetic material, and are held by the end plate to form an annular flow path therebetween. The end plate is a disk-shaped material made of a non-magnetic material, and includes a plurality of arc-shaped holes communicating with the annular flow path, an annular recess that engages with the protrusion at the end of the inner yoke, and a piston rod fixing purpose. And an annular groove with which the ring engages. Further, the inner yoke and the end plate are fixed by caulking the outer edges of both ends of the outer yoke.
US Pat. No. 6,260,675

  In such a damping force variable damper, it is necessary to incorporate components such as an outer yoke, an inner yoke, and a coil inside the piston. Moreover, it is necessary to pull out the lead wire of the coil to the outside through the inner hole of the piston rod. Therefore, it is necessary to take measures to prevent the MRF from leaking to the outside through the inner hole of the piston rod or the like from the gap between the components inside the piston. At the same time, it is desired that the assembly of the piston can be realized easily and at low cost.

  In particular, in order to increase the variable range of the damping force of the damping force variable damper, it is desirable to reduce the damping force during non-excitation, but to that end, it is necessary to minimize the axial length of the piston. The piston design must be highly streamlined.

  In view of the problems of the prior art, a main object of the present invention is to provide a damping force variable damper that is compact and easy to assemble in a variable damping force damper using an MRF. .

  The second object of the present invention is to provide a damping force variable damper having a suitable sealing structure for MRF.

  A third object of the present invention is to reduce the size of a piston incorporating a magnetic circuit in a variable damping force damper using MRF, thereby reducing the damping force when not energized and the variable width of the damping force. Is to make it even larger.

  According to the present invention, such an object is achieved by a cylinder filled with a magnetic fluid or a magnetorheological fluid and connected to one of a vehicle body side member and a wheel side member, and the cylinder as a side liquid chamber. A piston that is divided into other liquid chambers and has a flow path through which the magnetic fluid or magnetorheological fluid flows between the one liquid chamber and the other liquid chamber; the vehicle body side member; and the wheel side member The magnetic fluid that passes through the flow path through a magnetic field generated by flowing a current through the coil, and a piston rod that connects the other of the piston rod to the piston and a coil provided in the piston. A damping force variable damper whose damping force is controlled by being applied to the magnetorheological fluid, wherein the piston rod has an inner hole for drawing out a lead wire of the coil, and the inner yoke A combination of at least two parts in the axial direction, and the two parts are fitted to each other via an O-ring, thereby allowing the piston rod inner hole to be in contact with the magnetic fluid or magnetorheological fluid in the cylinder. The rod or cylindrical extension of the resin mold is fitted to any part of the inner yoke via an O-ring, so that the piston rod inner hole is connected to the inside of the cylinder. This is achieved by providing a damping force variable damper characterized by sealing against the magnetic fluid or magnetorheological fluid.

  According to such a configuration, by simply interposing an O-ring and simply assembling the components of the piston, a suitable sealing property is ensured, and assembly can be performed easily and at low cost. In particular, it is not necessary to increase the dimensional accuracy of the parts so much, and a resin mold or the like is not required except for the coil. Furthermore, no special equipment is required for assembly.

  Hereinafter, an embodiment in which the present invention is applied to a rear suspension of a four-wheel vehicle will be described in detail with reference to the drawings.

  As shown in FIG. 1, the rear suspension 1 of the present embodiment is a so-called H-type torsion beam suspension, and a torsion beam 4 that connects the left and right trailing arms 2 and 3, and an intermediate portion between both trailing arms 2 and 3. The left and right rear wheels 7 and 8 are suspended from a pair of left and right coil springs 5 and a pair of left and right dampers 6 as suspension springs. The damper 6 is a damping force variable damper using MRF (Magneto-Rheological Fluid) as a working fluid, and the damping force is variably controlled by an ECU 9 installed in a trunk room or the like.

  As shown in FIG. 2, the damper 6 of the present embodiment is a monotube type (de carvone type), and has a cylindrical cylinder 12 filled with MRF, and slides in the axial direction with respect to the cylinder 12. A piston rod 13 that is attached to the tip of the piston rod 13, a piston 16 that divides the inside of the cylinder 12 into an upper liquid chamber (one side liquid chamber) 14 and a lower liquid chamber (other side liquid chamber) 15, and the cylinder 12 The main components are a free piston 18 that defines a high-pressure gas chamber 17 in the lower portion of the cylinder, a cover 19 that prevents dust from adhering to the piston rod 13 and the like, and a bump stop 20 that performs buffering during full bouncing.

  The cylinder 12 is connected to the upper surface of the trailing arm 2 that is a wheel side member via a bolt 21 that is fitted into the eyepiece 12a at the lower end. The piston rod 13 is connected to a damper base (wheel house upper part) 24 which is a vehicle body side member through an upper and lower pair of bushes 22 and a nut 23.

  FIG. 3 shows details of the piston 16. An inner yoke 26 made of a ferromagnetic material having a columnar shape is provided at the center of the piston 16, and one end of the piston rod 13 is coupled to one axial end thereof. The inner yoke 26 includes two portions 26a and 26b divided in the axial direction. A female screw hole 49 is provided at the center of the end portion of the first portion 26a on the piston rod 13 side on the side away from the piston rod 13. A male screw projection 48 is provided at a portion of the second portion 26 b that faces the female screw hole 49, and is screwed into the female screw hole 49. A concave portion 50 for engaging a tool for screwing and fastening both portions of the inner yoke 26 to each other is provided at the center of the outer end portion of the second portion 26b in the axial direction.

  Radial flanges 25a and 25b are provided on the outer circumferences of the axially opposite end surfaces of the parts 26a and 26b of the inner yoke 26, and a ferromagnetic material is interposed between the flanges 25a and 25b via an end piece 32. A cylindrical flux ring, that is, an outer yoke 40 is sandwiched. That is, the end piece 32 and the outer yoke 40 are sandwiched between the flanges 25a and 25b without loosening by screwing the portions 26a and 26b of the inner yoke 26 together. The end piece 32 is made of a ferromagnetic material or a non-magnetic material, and includes four arc-shaped slots 36 provided at equal intervals in the circumferential direction. Further, the inner peripheral surface of the outer yoke 40 is opposed to the outer peripheral surface of the inner yoke 26 with a gap 41 at a predetermined interval concentrically. The outer peripheral surfaces of the end piece 32 and the outer yoke 40 cooperate with each other to define the outer peripheral surface of the piston 16. The outer peripheral surface itself may be a sliding surface of the piston 16 or may be used as a sliding surface of the piston 16 by using a piston ring member or a coating not shown separately.

Further, the piston rod 13 is coupled to the bottom surface of the recess 35 provided at the center of the opposed end surface of the inner yoke 26 by a friction welding method. The friction welding method is a technique in which members to be joined (for example, metal, resin, etc.) are rubbed together at high speed, and the members are softened by the frictional heat generated at the same time, and at the same time pressure is applied to join.

  An annular groove 28 is provided in the axially intermediate portion of the outer periphery of the inner yoke 26, and the coil 30 is received therein and embedded in the resin mold 29. In this case, the coil 30 is a coil wound in the circumferential direction of the inner yoke 26. Further, an axially extending portion 31 formed by extending a portion of the inner yoke 26 in the axial direction so as to overhang toward the outer periphery of the coil 30 is provided on the outer peripheral portion side of the annular groove 28. Yes. In the illustrated embodiment, the axially extending portion 31 extends symmetrically in the axial direction from both sides of the annular groove 28. In this way, the outer peripheral portion of the inner yoke 26 defines an outer peripheral surface that forms a circumferential surface having a substantially constant radius as a whole, and the portions located on both sides of the annular groove 28 serve as both portions 26a and 26b of the inner yoke 26. There is no.

  The split surfaces 33 of both portions of the inner yoke 26 are located on the same plane as the side surface of the annular groove 28 on the side away from the piston rod 13.

    As best shown in FIG. 5, the coil 30 is held by a resin mold 29 in an annular space defined between both portions of the inner yoke 26. In addition to the annular main body portion 56, the resin mold 29 has a diameter portion 51 extending in the diameter line direction with respect to the end surface on the piston rod 13 side of the main body portion 56, and the piston rod 13 from the center of the diameter portion. It has a large-diameter rod portion 52 that protrudes toward the end, and a small-diameter rod portion 53 that coaxially projects from the free end surface of the large-diameter rod portion. The lead wire 44 of the coil 30 passes through the inside of the large-diameter rod portion 52 and the small-diameter rod portion 53 from the coil 30 through the diameter portion 51 and is drawn out from the inside of the inner hole 46 of the piston rod 13. .

  Further, the small-diameter rod portion 53 enters into the center hole 54 in the first portion 26 a of the inner yoke 26, and an O-ring 55 is sandwiched between the two portions, so that the lead wire 44 is pulled out. The inner hole 46 of the piston rod 13 is sealed against the MRF fluid in the damper.

  Next, the operation point of the damper 6 will be described. When the wheel is relatively displaced with respect to the vehicle body due to traveling of the vehicle or the like, the displacement is transmitted to the piston 16 via the piston rod 13, and a relative displacement is caused between the piston 16 and the cylinder 12. As a result, the volumes of the two liquid chambers 14 and 15 change, and in response to the change, MRF (Magneto-Rheological Fluid) changes the arc-shaped slot 36, inner yoke 26 and outer yoke 40 of one end plate 34a. And the arc-shaped slot 36 of both end pieces 32. When not energized, the MRF flows with relatively little resistance and generates a low damping force that is generally proportional to the relative speed between the piston 16 and the cylinder 12. When the coil 30 is energized, when the MRF passes through the gap between the inner yoke 26 and the outer yoke 40, a strong flow path resistance is caused by the magnetic field formed in the gap 41, and the piston 16 and the cylinder 12 are generally. A high damping force proportional to the relative speed between the two is generated. By utilizing such characteristics and supplying a controlled current to the coil 30, desired damper control is realized.

  FIG. 6 shows details of the piston 16 in the second embodiment of the damper 6 of the present invention. In FIG. 6, the same reference numerals are given to portions corresponding to the above-described embodiment, and detailed description thereof is omitted.

  In the present embodiment, a thin cylindrical portion 62 extends in the direction of the second portion 26b from the outer periphery of the first portion 26a of the inner yoke 26. The outer periphery of the thin cylindrical portion 62 defines the same cylindrical surface as the outer contour of the first portion 26 a of the inner yoke 26, and the inner periphery of the thin cylindrical portion 62 is the outer contour of the second portion 26 b of the inner yoke 26. And defining a complementary cylindrical surface and is in close contact with the outer periphery substantially without any gap. An annular groove 63 is provided on the outer periphery of the second portion 26b of the inner yoke 26 in the vicinity of the outer end in the axial direction, and an O-ring 64 received therein abuts on the inner periphery of the thin cylindrical portion 62. The interior of the piston 16 is sealed against MRF fluid.

  The thin cylindrical portion 62 includes a base end portion made of a ferromagnetic material similar to the first portion 26a of the inner yoke 26, and a magnetic gap portion made of a non-magnetic material over a predetermined length in the axial center portion of the coil 30. 60, and a free end portion 61 made of a ferromagnetic material similar to the second portion 26b of the inner yoke 26. The thin-walled cylindrical portion 62 is formed by joining different metal pieces of corresponding shapes by a method such as friction welding or electric heating welding of different metals.

  The lead wire 44 of the coil 30 is drawn to the outside from the inner hole 46 of the piston rod 13 through a flexible printed circuit board-like strip 65 extending from the inner peripheral portion of the annular resin mold 29. The first portion 26 a of the inner yoke 26 is provided with a slot extending in the radial direction and the axial direction for receiving the strip 65.

  7 and 8 show details of the piston 16 in the third embodiment of the damper 6 of the present invention. 7 and 8, the same reference numerals are given to portions corresponding to the above-described embodiment, and detailed description thereof is omitted.

  The inner yoke 26 is composed of two parts divided in the axial direction, and both parts collide with each other so as to sandwich the resin mold 29 in which the coil 30 is embedded. An axial flange 82 is provided on the outer periphery of the abutting surface of the first portion 26 a of the inner yoke 26, and a circular recess 80 is defined by the flange. The resin mold 29 is disposed along the inner peripheral surface of the recess 80. A similar axial flange 82 is also provided on the outer periphery of the abutting surface of the second portion 26b of the inner yoke 26, and a magnetic air gap 84 is defined between the axial flange 82 of the first portion 26a. . A cylindrical protrusion 81 is provided at the center of the abutting surface of the second portion 26 b and is fitted into the inner peripheral surface of the resin mold 29. A groove for receiving a diameter portion of the resin mold 29 is further provided on the abutting surface of the first portion 26a.

  In the present embodiment, the outer yoke 71 made of a ferromagnetic material has a bottomed cylindrical shape, and the bottom surface of the outer yoke 71 via the disk-shaped spacer 85 is the surface on the piston rod side of the first portion 26a of the inner yoke 26. The inner yoke 26 is coaxially fitted so as to hit the motor. The open end or free end of the outer yoke 71 forms a thin portion 73, and the second portion 26 b of the inner yoke 26 is interposed via a disk-like lid plate 72 that is superposed on the outer axial end surface of the second portion 26 b of the inner yoke 26. It is squeezed against. One of the outer axial end surface of the second portion 26b and the facing surface of the lid plate 72 is provided with a recess, and the other is provided with a complementary protrusion that enters the recess.

    On the other hand, at the center of the bottom surface of the outer yoke 71 on the main body side, a hollow boss 74 projects coaxially, passes coaxially through the center hole of the first portion 26a of the inner yoke 26, and is connected to the second portion 26b of the inner yoke 26. The inner yoke 26 is centered and positioned with respect to the outer yoke 71 by being coaxially and complementarily fitted in the central recess. In the center hole of the hollow boss 74, a rod portion 75 that coaxially protrudes from the diameter portion of the resin mold 29 is fitted coaxially and complementarily. An annular groove 76 is provided on the inner peripheral surface of the center hole of the hollow boss 74, and an O-ring 77 that forms a seal between the rod portion 75 and the center hole of the hollow boss 74 is received. Similar to the above embodiment, the lead wire 44 of the coil 30 is drawn out from the inner hole 46 of the piston rod 13 through the diameter portion of the resin mold 29 and the inside of the rod portion 75. FIG. 9 shows such a structure in a simplified manner.

  In the embodiment of FIG. 10, instead of the annular groove 76, a large-diameter hole provided in the opening of the center hole 54 of the first portion 26 a of the inner yoke 26 on the side away from the piston rod 13. The rod portion 75 enters the inside 91 through an O-ring 77. The O-ring 77 is prevented from falling out of the large-diameter hole 91 by the diameter portion 51 of the resin mold 29 coming into contact with the O-ring 77. In other words, the large-diameter hole 91 and the contact surface of the diameter portion 51 cooperate to define an annular groove for holding the O-ring 77.

  The embodiment of FIG. 11 is the same as the embodiment of FIG. 10, but the rod portion 75 of the resin mold 29 includes a small diameter portion 75 a and a large diameter portion 75 b, and the small diameter portion 75 a is large via an O-ring 77. It enters into the radial hole 91. The annular shoulder surface between the small diameter portion 75a and the large diameter portion 75b and the large diameter hole 91 cooperate to define an annular groove for holding the O-ring 77. Therefore, the O-ring 77 abuts on the outer periphery of the small diameter portion 75a and the inner periphery of the opposed large diameter hole 91, and the required sealing performance is exhibited. The embodiment of FIG. 12 is similar to the embodiment of FIG. 11, but a metal sleeve 92 is fitted to the small diameter portion (not shown). The sleeve 92 may be insert-molded in the resin mold 29. In this case, the O-ring 77 abuts against the shoulder surface facing the axial direction of the large-diameter portion 75b and the bottom surface of the opposed large-diameter hole 91, and the required sealing performance is exhibited.

  In the embodiment of FIG. 13, the center hole 54 of the first portion 26 a of the inner yoke 26 has a smooth cylindrical surface, and an annular groove 93 is formed on the outer periphery of the rod portion 75 of the resin mold 29 protruding into the center hole 54. The O-ring 77 is received in the inside.

  In the embodiment of FIG. 14, an annular recess 94 coaxial with the outer periphery of the center hole 54 is formed at a predetermined axial depth on the end surface of the first portion 26 a of the inner yoke 26 on the side away from the piston rod 13. Is provided. An annular groove 95 is provided in the inner peripheral surface of the annular recess 94, and an O-ring 77 is received therein. On the other hand, on the resin mold 29 side, an annular projection 96 complementary to the annular recess 94 is provided and enters the annular recess 94. Therefore, the O-ring 77 comes into contact with the inner peripheral surface of the annular protrusion 96, and a required sealing effect is achieved.

  In the embodiment of FIG. 15, a small-diameter protrusion 97 is provided at the center of the end surface of the first portion 26a of the inner yoke 26 on the side away from the piston rod 13, and an annular recess 94 is coaxially formed on the outer periphery thereof. Is provided. On the resin mold 29 side, an annular protrusion 96 that is substantially complementary to the annular recess 94 is provided and enters the annular recess 94. As a result, an annular groove for holding the O-ring 77 is defined between the outer periphery of the small-diameter protrusion 97 and the inner periphery of the annular protrusion 96, and both axial end faces of the annular groove are the inner end of the inner yoke 26. 1 part 26 a and the opposite surface of the diameter part 51 of the resin mold 29.

  Although the description of the specific embodiment is finished as above, the present invention is not limited to the above embodiment and can be widely modified. For example, in the above embodiment, the present invention is applied to a damping force variable damper that constitutes a rear suspension of a four-wheeled vehicle. However, the present invention can also be applied to a damping force variable damper for a front suspension. It can also be applied to a damping force variable damper for a two-wheeled vehicle or the like. Further, the shape, size, arrangement, and the like of the annular groove or the axially extending portion provided in the inner yoke are not limited to the examples in the above embodiment, and can be freely set according to design and manufacturing requirements .

1 is a perspective view of a rear suspension to which the present invention is applied. It is a longitudinal cross-sectional view of the damper based on this invention. FIG. 3 is an enlarged view of part III in FIG. 2 showing a first embodiment of the present invention. It is the same longitudinal cross-sectional view seen about the cross section orthogonal to the cross section of FIG. It is a perspective view which fractures | ruptures a part and shows the resin mold with which the coil was embed | buried with the extension part. It is the same longitudinal cross-sectional view as FIG. 3 which shows the 2nd Example of this invention. It is the same longitudinal cross-sectional view as FIG. 3 which shows the 3rd Example of this invention. FIG. 8 is a longitudinal sectional view similar to FIG. 3, illustrating a third embodiment of the present invention, viewed from a section orthogonal to the section of FIG. 7. FIG. 6 is a diagram schematically illustrating a third embodiment of the present invention. It is a diagram showing a modified embodiment of the present invention in a simplified manner. It is a diagram which simplifies and shows another modified example of this invention. FIG. 6 is a diagram schematically showing still another modified embodiment of the present invention. FIG. 6 is a diagram schematically showing still another modified embodiment of the present invention. FIG. 6 is a diagram schematically showing still another modified embodiment of the present invention. FIG. 6 is a diagram schematically showing still another modified embodiment of the present invention.

Explanation of symbols

2 Trailing arm (wheel side member)
6 Damper 12 Cylinder 13 Piston rod 14 Upper liquid chamber (one side liquid chamber)
15 Lower liquid chamber (other side liquid chamber)
16 Piston 22 Damper base (vehicle body side member)
26 Inner yoke 28 Annular groove 30 Coil 52 Large-diameter rod part 53 Small-diameter rod part 54 Center hole 55, 64, 77 O-ring 61 Free end part 63 Annular groove 74 Hollow boss 76 Annular groove 75 Rod part

Claims (2)

A cylinder filled with a magnetic fluid or a magnetorheological fluid and connected to one of a vehicle body side member and a wheel side member; and the cylinder is divided into a one side liquid chamber and another side liquid chamber and the magnetic fluid Alternatively, a piston in which a flow path for flowing a magnetorheological fluid between the one-side liquid chamber and the other-side liquid chamber is formed, and a piston that connects the other of the vehicle body-side member and the wheel-side member to the piston. A damping force is generated by applying a magnetic field generated by passing a current through the rod to the magnetic fluid or the magnetorheological fluid having a rod and a coil provided in the piston. A damping force variable damper to be controlled,
The piston rod has an inner hole for pulling out a lead wire of the coil;
The inner yoke is formed by combining at least two portions in the axial direction, and both the portions are fitted to each other via an O-ring, so that the piston rod inner hole is formed into the magnetic fluid or magnetorheological fluid in the cylinder. Damping force variable damper characterized by sealing against. A cylinder filled with a magnetic fluid or a magnetorheological fluid and connected to one of a vehicle body side member and a wheel side member; and the cylinder is divided into a one side liquid chamber and another side liquid chamber and the magnetic fluid Alternatively, a piston in which a flow path for flowing a magnetorheological fluid between the one-side liquid chamber and the other-side liquid chamber is formed, and a piston that connects the other of the vehicle body-side member and the wheel-side member to the piston. A rod and a coil provided in the piston via a resin mold, and a magnetic field generated by passing a current through the coil is applied to the magnetic fluid or the magnetorheological fluid passing through the flow path. A damping force variable damper whose damping force is controlled by
The piston rod has an inner hole for pulling out a lead wire of the coil;
The inner yoke is formed by combining at least two portions in the axial direction, and the rod or cylindrical extension of the resin mold is fitted to any portion of the inner yoke via an O-ring, thereby A damping force variable damper, wherein a hole is sealed against the magnetic fluid or magnetorheological fluid in the cylinder.

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