JP5193123B2 - Damper device - Google Patents

Description

  The present invention relates to a damper device, and more particularly to a damper device using a magnetic fluid or the like.

  A so-called suspension device is provided around the undercarriage of a vehicle such as an automobile in order to cushion the impact from the road surface and improve the ride comfort. This suspension device is provided with a spring that absorbs an impact from a road surface, a damper device that attenuates the vibration of the spring, and various arms that rotatably support a wheel.

  With regard to this type of damper device, for example, in Patent Document 1, a reduced diameter portion is provided on one end portion side of a piston rod to which a piston is connected via an annular step portion, and one end of the reduced diameter portion of the piston rod is provided. A damper structure is disclosed in which the stopper plate, the piston, and the other stopper plate are sequentially stacked, and the piston or the like is fixed by a nut fastened to the end of the reduced diameter portion of the piston rod.

  In Patent Document 2, a rebound stopper is locked to a portion of the piston rod that is axially spaced from the piston, and a rebound rubber that is backed up by the rebound stopper is provided. A damper structure is disclosed in which the rubber is in contact with a guide member held at one end of a damper tube to restrict the maximum extension stroke of the piston rod.

JP 2007-225023 A JP 2001-200908 A

  However, for example, due to the load acting on the pressure receiving surface of the piston, stress concentrates on the annular step portion provided at the boundary portion between the enlarged diameter portion and the reduced diameter portion of the piston rod having different outer diameters, and the piston rod There is a concern that the strength durability will be reduced.

  In addition, when assembling the piston to the piston rod, an assembly operation for locking the rebound stopper to the piston rod and an operation for positioning the piston at a predetermined position with respect to the annular step portion of the piston rod are required. As a result, the assembly process becomes complicated.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a damper device capable of improving the durability of the strength of the piston rod and simplifying the assembly process.

In order to achieve the above object, the present invention provides a cylinder tube in which a working fluid is sealed, a piston that is displaceably accommodated in the cylinder tube, and one end connected to the piston. The piston rod that is integrally displaced, the piston rod support member that is provided on the cylinder tube and supports the other end side of the piston rod, surrounds the outer peripheral surface of the piston rod, and the piston rod is extended most An elastic member that sometimes abuts against the piston rod support member and absorbs an impact, and a support member provided between the elastic member and the piston,
The support member includes a first wall portion on the elastic member side and a second wall portion on the piston side that extend in the radial direction at both ends along the axial direction of the piston rod, and the first wall portion, And a caulking portion that is provided between the second wall portion and caulked to the outer peripheral surface of the piston rod.

  According to the present invention, the support member that is firmly held at the predetermined portion of the piston rod through the caulking portion is provided, the elastic member is supported by the first wall portion of the support member, and the second of the support member is provided. The piston can be positioned at a predetermined position by pressing the piston press-fitted along the axial direction of the piston rod with the wall portion.

  Therefore, in the present invention, by having both the supporting action of the elastic member and the positioning action of the piston by the supporting member made of a single member, the number of parts can be reduced and the assembling man-hour can be simplified.

  Further, in the present invention, for example, since it is not necessary to form an annular step portion on the piston rod as in the prior art, stress concentration in the annular step portion is avoided and the strength durability of the piston rod is improved. Can do.

  Further, in the present invention, the load transmitted from the elastic member through the first wall portion is absorbed by the caulking portion of the support member, and at the time of press-fitting the piston transmitted from the piston through the second wall portion. When the positioning load is absorbed by the caulking portion of the support member, it is possible to suitably avoid that each load is transmitted to other parts.

  Further, according to the present invention, the working fluid is composed of a magnetorheological fluid or a magnetorheological fluid, and the piston is provided with a coil for exciting the magnetorheological fluid or the magnetorheological fluid, and a conducting wire for passing current to the coil It is provided along the hollow part of the piston rod.

  According to the present invention, the damper device has a variable damping force that changes the viscosity of the magnetorheological fluid by passing an electric current through the coil to excite the coil, and the conducting wire for energizing the coil is provided along the hollow portion of the piston rod. Even if the wiring is performed, strength and durability can be ensured without increasing the outer diameter of the piston rod.

  ADVANTAGE OF THE INVENTION According to this invention, while improving the durable durability of a piston rod, the damper apparatus which can simplify an assembly | attachment process can be obtained.

It is a longitudinal cross-sectional view along the axial direction of the damper apparatus which concerns on embodiment of this invention. It is a principal part expanded longitudinal cross-sectional view containing the piston shown in FIG. It is a principal part expansion longitudinal cross-sectional view of the damper apparatus which concerns on the comparative example which the present applicant devised. (A) is a partially omitted explanatory view showing the magnetic flux generated by exciting the coil in this embodiment, (b) is a partially omitted showing the magnetic flux generated by exciting the coil in the comparative example. It is explanatory drawing. (A) is the elements on larger scale which show the 1st modification of the support member which constitutes the damper device shown in Drawing 1, (b) is the elements on the same section which expand the longitudinal section which shows the 2nd modification of the above-mentioned support member. is there.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. FIG. 1 is a longitudinal sectional view along the axial direction of a damper device according to an embodiment of the present invention.

  A damper device according to an embodiment of the present invention is incorporated in a suspension system (not shown) that suspends wheels of a vehicle such as an automobile. This suspension system includes, for example, a suspension arm that supports a knuckle arm so as to move up and down with respect to the vehicle body, a damper device that connects the suspension arm and the vehicle body, and a spring that connects the suspension arm and the vehicle body. The

  Hereinafter, in the present embodiment, a damper device incorporated in a vehicle suspension system will be described as an example. However, the present invention is not limited to this and can be used for other purposes. In the present embodiment, a damper device having a variable damping force using a magnetorheological fluid, which will be described later, will be described as an example. However, the present invention is not limited to this.

  As shown in FIG. 1, a damper device 10 according to an embodiment of the present invention includes a bottomed cylindrical body, and one end (lower end) along the axial direction is attached to a suspension arm (not shown) via a rubber bush 12. A cylinder tube 16 connected and open at the other end is closed by a piston rod support member 14, and a piston slidably (displaceably) disposed along a cylinder chamber formed in the cylinder tube 16. 18 and so on.

  Further, the damper device 10 includes a hollow piston rod 20 having one end connected to the piston 18 and the other end exposed to the outside from the cylinder tube 16 and connected to a vehicle body (not shown) (for example, a strut tower), And a free piston 22 slidably provided on one end side (lower end side) of the cylinder tube 16.

  The piston rod support member 14 is fixed to the other end portion of the cylinder tube 16 so as to slidably support the other end portion side of the piston rod 20, and an elastic member 50 to be described later when the piston rod 20 is fully extended. It has the contact plate 23 which contacts. Between the piston rod support member 14 and the contact plate 23, a seal member 25 surrounding the outer peripheral surface of the piston rod 20 is provided. In this embodiment, when the piston rod 20 is extended to the maximum, the elastic member 50 described later is configured to contact the contact plate 23. However, the contact plate 23 is omitted and the piston rod is substantially omitted. You may make it contact | abut with the rod support member 14. FIG.

  The cylinder chamber formed inside the cylinder tube 16 is divided into one (upper) first fluid chamber 24a and the other (lower) second fluid chamber 24b by the piston 18, and the first fluid chamber 24a and The second fluid chamber 24b is filled with a magneto-rheological fluid (MRF) 26.

  The magnetorheological fluid 26 is made of, for example, a magnetic fluid formed by mixing microscale iron particles in oil or the like, and has a property that the viscosity changes when magnetism acts. Further, a gas chamber 28 filled with high-pressure gas is provided on one end side (lower end side) of the cylinder tube 16 closed by the free piston 22. The first fluid chamber 24 a and the second fluid chamber 24 b are provided so as to communicate with each other via a fluid passage 30 provided in the piston 18.

FIG. 2 is an enlarged longitudinal sectional view of a main part including the piston shown in FIG.
As shown in FIG. 2, the piston 18 is fitted on one end of the piston rod 20 along the radial direction and is locked via a C-ring 32, and the piston body 34. And a piston ring 36 slidably in contact with the inner peripheral surface of the cylinder tube 16.

  The piston body 34 is integrally provided with a resin sealing body 40 including a coil 38 molded with a non-conductive resin material. The coil 38 has a through hole (hollow portion) 42 of the piston rod 20. Are electrically connected to a harness (conductive wire) 44 routed along the line. In this case, the viscosity of the magnetorheological fluid 26 can be adjusted by energizing the coil 38 through the harness 44 wired through the through hole 42 of the piston rod 20 and exciting the coil 38. In addition, a sealing member 45 such as an O-ring is provided at a connection portion between one end of the piston rod 20 and the resin sealing body 40, for example.

  The piston 18 is fitted in the piston main body 34 and the piston ring 36 along the axial direction so as to face the first fluid chamber 24a and has a substantially disc-like first end plate 46a, and the first end. On the opposite side of the plate 46a, the piston body 34 and the piston ring 36 are fitted and coupled to each other to have a substantially disc-shaped second end plate 46b facing the second fluid chamber 24b, and the first end plate 46a, The piston body 34 and the second end plate 46 b are integrally coupled by a plurality of bolts 48.

  On the piston rod 20 adjacent to the first end plate 46a, as shown in FIG. 2, an elastic member 50 made of a ring body surrounding the outer peripheral surface of the piston rod 20, for example, formed of rubber or the like, A support member 52 that supports the elastic member 50 on one axial side of the piston rod 20 is provided.

  The support member 52 includes a cylindrical body portion 54 that extends in the axial direction along the outer peripheral surface of the piston rod 20, and both end portions along the axial direction of the body portion 54 that extend along the radial direction. The first wall 56 and the second wall 58 are present.

  In this case, as will be described later, the body portion 54, the first wall portion 56, and the second wall portion 58 are preferably integrally formed of a nonmagnetic material such as stainless steel, aluminum, or an aluminum alloy. The first wall portion 56 and the second wall portion 58 are each formed in a disk shape having substantially the same diameter, and the first end plate 46a side with respect to the thickness of the first wall portion 56 on the elastic member 50 side. The thickness of the second wall portion 58 is slightly thick.

  A caulking portion 60 that is plastically deformed by being pressed almost uniformly radially inward by a caulking means (not shown) is provided at a substantially central portion of the body portion 54 between the first wall portion 56 and the second wall portion 58. Provided. The caulking portion 60 is filled in the annular groove portion 62 of the piston rod 20 that has been pressurized and plastically deformed, and the annular groove portion 62 is tightened so that the support member 52 is firmly positioned at a predetermined position of the piston rod 20. Retained.

  The elastic member 50 has a function of absorbing an impact when the piston rod 20 contacts the contact plate 23 of the piston rod support member 14 when the piston rod 20 is fully extended.

  In this case, the first wall portion 56 of the support member 52 contacts the elastic member 50 and functions as the elastic member side, while the second wall portion 58 of the support member 52 is connected to the first end plate 46 a of the piston 18. It is provided to contact and function as the piston side.

  The damper device 10 according to the present embodiment is basically configured as described above. Next, the function and effect will be described in relation to a comparative example.

  FIG. 3 is an enlarged vertical cross-sectional view of a main part of a damper device according to a comparative example devised by the present applicant. Note that the same components as those of the damper device 10 according to the present embodiment illustrated in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the damper device 100 according to the comparative example, the piston rod 104 is formed with a support element 108 having a radial flange portion 102 that supports the elastic member 50, a cylindrical portion 106 crimped to the piston rod 104, and the piston rod 104. 2 differs from the damper device 10 shown in FIG. 2 in that the annular guide plate 112 that contacts the annular stepped portion 110 and positions the piston 18 at a predetermined position is provided separately (two members). .

  Next, for example, assuming that a lateral force in a direction substantially orthogonal to the axis of the piston rods 20 and 104 is applied to each of the damper devices 10 and 100, the comparison example and the present embodiment will be described below. To do.

  In the damper device 100 according to the comparative example, it is necessary to position the piston 18 and the piston rod with respect to each other while ensuring the rigidity necessary to press-fit the piston rod 104 into the center hole of the piston 18. If an annular step 110 is provided, the diameter-expanded portion expanded by the annular step 110 becomes thicker than the outer diameter of a conventional piston rod (not shown), and a special piston rod is manufactured. There is a need.

  That is, in the damper device 100 according to the comparative example, in the piston rod 104 having the annular step portion 110, it is necessary to manufacture a special piston rod 104 having an enlarged diameter portion formed by expanding the diameter compared with the reduced diameter portion. There is a problem that the production cost is increased because other general-purpose piston rods that can be mass-produced cannot be used.

  On the other hand, in this embodiment, it is not necessary to provide the annular stepped portion 110 at the portion of the piston rod 20 to which the piston 18 is assembled, and other general-purpose piston rods that can be mass-produced can be used. Cost can be reduced and inventory management becomes easy.

Next, it is assumed that the piston 18 is positioned and assembled with respect to the piston rods 20 and 104.
In the damper device 100 according to the comparative example, when the piston 18 is press-fit along the piston rod 104 from the axial direction, the piston 18 is pressed against the annular guide plate 112 that is in contact with the annular stepped portion 110, thereby the piston 18. Must be positioned at a predetermined position. As a result, in the damper device 100 according to the comparative example, the guide plate 112 needs to be formed of a hard material having a high strength capable of withstanding the pressing load of the piston 18.

  Therefore, in the damper device 100 according to the comparative example, it is necessary to separately provide a high-strength member formed of a hard material, that is, a steel guide plate 112 as a load receiving member in the annular step portion 110. As a result, in the damper device 100 according to the comparative example, there is a problem that the number of parts increases, the manufacturing cost increases, and the number of assembling steps increases.

  Further, in the damper device 100 according to the comparative example, the support element 108 that cushions the impact by the elastic member 50 and regulates the stroke amount when the piston rod 104 is fully extended is crimped and held on the piston rod 104. Yes. For this reason, the support element 108 needs to be formed of a material (a material having high deformability) that can be easily plastically deformed by pressure during caulking.

  On the other hand, in the present embodiment, a support member 52 that is firmly held at a predetermined portion of the piston rod 20 via the caulking portion 60 is provided, and the elastic member 50 is moved by the first wall portion 56 of the support member 52. While supporting, the piston 18 press-fit along the axial direction of the piston rod 20 with the 2nd wall part 58 of the said supporting member 52 can be pressed, and the said piston 18 can be positioned in a predetermined position.

  As described above, in the present embodiment, the support member 52 made of a single member has both the support action of the elastic member 50 and the positioning action of the piston 18, thereby reducing the number of parts and simplifying the assembly man-hours. can do.

  Moreover, in this embodiment, since the annular step part 110 formed in the piston rod 104 of the damper device 100 according to the comparative example is unnecessary, stress concentration in the annular step part 110 is avoided and the durability of the piston rod 20 is durable. Can be improved.

  Furthermore, in the present embodiment, the load transmitted from the elastic member 50 via the first wall portion 56 is absorbed by the crimping portion 60 of the support member 52 and transmitted from the piston 18 via the second wall portion 58. Since the positioning load at the time of press-fitting the piston 18 is absorbed by the caulking portion 60 of the support member 52, it is possible to suitably avoid that each load is transmitted to other parts.

  Here, those skilled in the art can easily conceive that the support member 108 in the damper device 10 according to the present embodiment is configured by integrating the support element 108 and the guide plate 112 in the damper device 100 according to the comparative example. However, in the present embodiment, the following technical difficulties have been overcome.

  In other words, the support element 108 according to the comparative example needs to be formed of a material that can be easily plastically deformed by pressurization during crimping (a material with high deformability), while the guide plate according to the comparative example. 112 needs to be formed of a hard material having a high strength capable of withstanding the pressing load of the piston 18, and it is technically difficult to integrate those having properties in opposite directions in the comparative example. It is.

  For example, in the comparative example, when the support element 108 and the guide plate 112 are integrated with a relatively soft material, the elastic member 50 and the contact plate 23 come into contact with each other when the piston rod 104 is fully extended. May be transmitted to the piston 18 via the guide plate 112 and the piston rod 104, and the vibration damping function may be reduced.

  In contrast, in the present embodiment, the first wall portion 56 that receives the load on the elastic member 50 side when the piston rod 20 is fully extended, and the second wall portion 58 that receives the load on the piston 18 side during press-fit assembly. And a caulking portion 60 (body portion 54) in which an intermediate portion between the first wall portion 56 and the second wall portion 58 is caulked substantially uniformly along the circumferential direction with a constant pressure against the piston rod 20. ), The technical difficulty is overcome.

  In this case, compared with the comparative example of FIG. 3, in this embodiment, it becomes possible to shorten a dimension only by the separation distance S of the broken line S1 and the broken line S2 shown in FIG. 2, and the damper apparatus 10 whole is small and lightweight. And unsprung weight can be reduced.

  FIG. 4A is a partially omitted explanatory view showing the magnetic flux generated by exciting the coil in this embodiment, and FIG. 4B shows the magnetic flux generated by exciting the coil in the comparative example. FIG.

  In the comparative example, the use of the steel guide plate 112 causes magnetic flux leakage (see B portion in FIG. 4B). In the present embodiment, the support member 52 is, for example, non- By using stainless steel, aluminum alloy or the like made of a magnetic material, the magnetic flux passing through the support member 52 can be reduced and magnetic flux leakage can be reduced (see part A in FIG. 4A). As a result, in the present embodiment, the viscosity of the magnetorheological fluid 26 can be suitably controlled by increasing the magnetic flux density of the gap flow path.

  Next, FIG. 5A is a partially enlarged longitudinal sectional view showing a first modification of the support member constituting the damper device shown in FIG. 1, and FIG. 5B is a second modification of the support member. It is a partial expanded longitudinal cross-sectional view shown.

  In the support member 52a according to the first modification shown in FIG. 5 (a), two members 72a having a first screw portion 70a and a second screw portion 70b made of reverse screws engraved in opposite directions to each other, 2 is different from the support member 52 shown in FIG. 2 in that the support member 52a is formed by integrally screwing 72b with the male thread portion of the piston rod 20.

  In the support member 52b according to the second modification shown in FIG. 5 (b), it is not between the first wall portion 56 and the second wall portion 58 but from the first wall portion 58 toward the piston rod support member 14 side. 2 is different from the support member 52 shown in FIG. 2 in that an annular portion 74 projecting a predetermined length in the axial direction is formed and a caulking portion 60 is provided on the annular portion 74. Since the other functions and effects are the same as those of the support member 52 shown in FIG.

DESCRIPTION OF SYMBOLS 10 Damper apparatus 14 Piston rod support member 16 Cylinder tube 18 Piston 20 Piston rod 26 Magnetic viscous fluid (working fluid)
38 Coil 42 Through hole (hollow part)
44 Harness (conductor)
50 elastic member 52, 52a, 52b support member 56 first wall portion 58 second wall portion 60 caulking portion

Claims (2)

A cylinder tube filled with a working fluid;
A piston housed in a freely displaceable manner in the cylinder tube;
A piston rod having one end connected to the piston and integrally displaced with the piston;
A piston rod support member provided on the cylinder tube and supporting the other end side of the piston rod;
An elastic member that surrounds the outer peripheral surface of the piston rod and absorbs an impact by contacting the piston rod support member when the piston rod is fully extended;
A support member provided between the elastic member and the piston;
With
The support member includes a first wall portion on the elastic member side and a second wall portion on the piston side that extend in the radial direction at both ends along the axial direction of the piston rod, and the first wall portion, A damper device comprising: a caulking portion provided between the second wall portion and caulking to an outer peripheral surface of the piston rod. The damper device according to claim 1, wherein
The working fluid is composed of a magnetorheological fluid or a magnetic fluid,
The piston is provided with a coil for exciting the magnetorheological fluid or magnetic fluid,
A damper device characterized in that a conducting wire for passing an electric current to the coil is provided along a hollow portion of the piston rod.

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