U.S. patent application number 16/767620 was filed with the patent office on 2020-11-26 for damping stopper.
The applicant listed for this patent is NOK CORPORATION. Invention is credited to Yuki HANADA.
Application Number | 20200370618 16/767620 |
Document ID | / |
Family ID | 1000005037685 |
Filed Date | 2020-11-26 |
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United States Patent
Application |
20200370618 |
Kind Code |
A1 |
HANADA; Yuki |
November 26, 2020 |
DAMPING STOPPER
Abstract
A damping stopper is interposed between two members axially
displaced relative to each other and is provided with an elastic
body which, when the interval between the two members decreases, is
axially compressed by the two members and expands radially outward.
In the elastic body, a second member suppressing the expansion is
located in one axial region and attached to the outer periphery.
When axially compressed by the two members, the elastic body
expands while receiving resistance by the second member. The
expanding elastic body contacts the side wall of one of the two
members.
Inventors: |
HANADA; Yuki; (Tottori,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NOK CORPORATION |
Tokyo |
|
JP |
|
|
Family ID: |
1000005037685 |
Appl. No.: |
16/767620 |
Filed: |
November 27, 2018 |
PCT Filed: |
November 27, 2018 |
PCT NO: |
PCT/JP2018/043480 |
371 Date: |
May 28, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16F 2226/042 20130101;
F16F 2226/04 20130101; F16F 2224/025 20130101; F16F 15/022
20130101; F16F 13/02 20130101; F16F 2224/0208 20130101; F16F
2236/045 20130101; F16F 2224/02 20130101; B62D 3/12 20130101; F16F
2232/08 20130101; F16F 2234/02 20130101 |
International
Class: |
F16F 13/02 20060101
F16F013/02; F16F 15/02 20060101 F16F015/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 2017 |
JP |
2017-240274 |
Claims
1. A damping stopper comprising: an elastic body provided between
two members axially displaced relative to each other, the elastic
body being configured to be axially compressed by the two members
and to radially outward when an interval between the two members
decreases; and a second member attached to an outer periphery of
the elastic body in one axial region of the elastic body, the
second member being configured to suppress expansion of the elastic
body in the one region, wherein the elastic body expands while
receiving resistance by the second member to contact a side wall
provided in one member of the two members.
2. The damping stopper according to claim 1, wherein the second
member is a ring body having rigidity such that the second member
does not contact the side wall when the elastic body expanding
radially outward contacts the side wall.
3. The damping stopper according to claim 2, wherein the ring body
has a shape in which a dimension in a direction orthogonal to an
axis is larger than an axial dimension.
4. The damping stopper according to claim 3, wherein the ring body
is assembled to an annular mounting groove provided in the elastic
body.
5. The damping stopper according to claim 2, wherein the ring body
is attached to a position where the elastic body is divided into a
portion having a long axial length and a portion having a short
axial length.
6. The damping stopper according to claim 1, wherein the second
member has elasticity such that the second member expands radially
outward when pressed by the elastic body expanding radially outward
and rigidity higher than rigidity of the elastic body such that the
second member contacts the side wall earlier than the elastic
body.
7. The damping stopper according to claim 6, wherein the second
member is a ring body.
8. The damping stopper according to claim 3, wherein the ring body
is attached to a position where the elastic body is divided into a
portion having a long axial length and a portion having a short
axial length.
9. The damping stopper according to claim 4, wherein the ring body
is attached to a position where the elastic body is divided into a
portion having a long axial length and a portion having a short
axial length.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a U.S. National Phase application of
International Application No. PCT/JP2018/043480, filed on Nov. 27,
2018 and published in Japanese as WO2019/116878A1 on Jun. 20, 2019
and claims priority to Japanese Patent Application No. 2017-240274,
filed on Dec. 15, 2017. The entire disclosures of the above
applications are expressly incorporated by reference herein.
BACKGROUND
Technical Field
[0002] The disclosure relates to a damping stopper stopping the
displacement of a movable member, the relative displacement between
members, and the like while exhibiting a damping action.
Related Art
[0003] The damping stopper is used as a rack end stopper for an end
of a steering rack provided in a steering gear of a vehicle, for
example. As illustrated in FIG. 6, the rack end stopper compresses
and deforms an elastic body 82 containing a rubber material between
a rack housing 51 and a rack 61 axially facing each other and
axially displaced relative to each other.
[0004] A damping stopper 81 damps a shock when the rack 61 collides
with the rack housing 51 when a steering wheel is vigorously turned
to a full lock in a hydraulically/electrically assisted steering
rack, for example.
[0005] The damping of the shock by the damping stopper 81 is
performed by absorbing the kinetic energy by the weight and the
speed of a movable object (rack 61) by the displacement and the
reaction force of the damping stopper 81 (elastic body 82). As
illustrated in a graph of FIG. 7, the absorbable energy amount is
defined by the size of an area S illustrated by a diagram obtained
by the displacement amount and the reaction force of the damping
stopper 81.
[0006] Therefore, in order to increase the absorbable energy
amount, it is common to enlarge the area S by increasing the
displacement amount of the damping stopper 81 or increasing the
reaction force (Rigidity=Spring constant).
[0007] The above-described technique has room for improvement in
the following points.
[0008] The damping stopper 81 requires a proper distortion in order
to obtain a high reaction force like a nonlinear region as the
characteristic of a common elastic material. In this point, the
above-described structure requires an increase in the stopper size
in order to satisfy a request function. However, a design space is
limited due to the relationship with peripheral components, and
thus the size increase is not easy.
[0009] As a solution technique for the above-described problem, it
is considered to obtain a high reaction force by filling, with the
elastic body 82 which is deformed by an input, a clearance c
between a mating component (housing 51) and the stopper 81.
[0010] However, according to this technique, the reaction force
sharply rises when the elastic body 82 reaches a filled state, and
therefore efficient energy absorption cannot be performed. As a
result, the absorbable energy amount cannot be increased.
[0011] It is an object of the disclosure to provide a damping
stopper capable of increasing the absorbable energy amount.
SUMMARY
[0012] A damping stopper of the disclosure is provided with an
elastic body provided between two members axially displaced
relative to each other and, when the interval between the two
members decreases, axially compressed by the two members and
expanding radially outward and a second member attached to an outer
periphery of the elastic body in one axial region of the elastic
body and suppressing the expansion of the elastic body in the one
region, in which the elastic body expands while receiving
resistance by the second member to thereby contact a side wall
provided in one member of the two members.
Effect
[0013] According to the disclosure, a resistance force by the
second member is generated in an expansion process of the elastic
body, and thus the absorbable energy amount can be increased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a cross-sectional view of a principal portion of a
damping stopper of a first embodiment.
[0015] FIG. 2 is a cross-sectional view of a principal portion
illustrating the operation state of the damping stopper.
[0016] FIG. 3 is a graph illustrating the relationship between the
displacement amount and the reaction force in the damping
stopper.
[0017] FIG. 4 is a cross-sectional view of a principal portion of a
damping stopper of a second embodiment.
[0018] FIG. 5 is a graph illustrating the relationship between the
displacement amount and the reaction force in the damping
stopper.
[0019] FIG. 6 is a cross-sectional view of a principal portion of a
damping stopper described in the background art.
[0020] FIG. 7 is a graph illustrating the relationship between the
displacement amount and the reaction force in the damping
stopper.
DETAILED DESCRIPTION
[0021] A damping stopper 11 of this embodiment is an example of a
rack end stopper of a steering rack provided in a steering gear of
a vehicle. As illustrated in FIG. 1 or FIG. 4, the damping stopper
11 is interposed between a rack housing 51 and a rack 61 as two
members axially facing each other and axially displaced relative to
each other.
[0022] The rack housing 51 has an end surface 52 having a planar
shape perpendicular to the axis. On the outer periphery of the end
surface 52, a level difference 53 is provided. On the inner
peripheral surface of the level difference 53, a side wall 54 is
provided. The rack 61 has an end surface 62 axially facing the end
surface 52 of the rack housing 51. On the inner periphery of the
end surface 62, a level difference 63 is provided. On the outer
peripheral surface of the level difference 63, a side wall 64 is
provided. Therefore, an annular mounting space 71, four sides of
which are surrounded by the end surface 52 and the side wall 54 of
the rack housing 51 and the end surface 62 and the side wall 64 of
the rack 61, is provided. The damping stopper 11 forms an annular
shape as a whole and mounted in the mounting space 71.
First Embodiment
[0023] A first embodiment is described based on FIG. 1 to FIG.
3.
[0024] As illustrated in FIG. 1, the damping stopper 11 has an
elastic body 21 axially compressed between the end surface 52 of
the rack housing 51 and the end surface 62 of the rack 61.
[0025] The elastic body 21 is formed into an annular shape by a
predetermined rubber material. To one axial end (upper side in the
figure, the rack 61 side) and the inner peripheral surface, a metal
attachment ring 31 presenting an L-shaped cross section is bonded
(vulcanized and bonded). As illustrated in FIG. 2, when the rack 61
is displaced in the direction of approaching the rack housing 51
(direction indicated by an arrow D) so that the interval between
the end surfaces 52 and 62 decreases, the elastic body 21 is
axially compressed by the rack housing 51 and the rack 61 and
expands radially outward.
[0026] In the implementation of the disclosure, a metal attachment
ring (not illustrated) may be bonded also to the other axial end
(lower side in the figure, the rack housing 51 side) of the elastic
body 21.
[0027] The damping stopper 11 has a second member 41 attached to
one axial part of the outer periphery in the elastic body 21 and
restricting the expansion of the elastic body 21 in the one axial
part. More specifically, the second member 41 is attached to the
outer periphery of the elastic body 21 in one axial region of the
elastic body 21 and suppresses the expansion of the elastic body 21
in the one region.
[0028] The second member 41 is a ring body having rigidity such
that the second member 41 does not contact the side wall 54 when
the elastic body 21 expanding radially outward contacts the side
wall 54. The ring body is formed of metal as an example and formed
of resin as another example. The ring body has a shape in which the
dimension in a direction orthogonal to the axis is larger than the
axial dimension and is assembled to an annular mounting groove 24
provided in the elastic body 21. The mounting groove 24 is a groove
provided beforehand in the outer peripheral surface of the elastic
body 21.
[0029] The mounting groove 24 is formed at a position where the
elastic body 21 is divided into a portion 22 of a length L.sub.1
and a portion 23 of a length L.sub.2. Therefore, the ring body
configuring the second member 41 is attached to a position where
the elastic body 21 is divided into the portion 22 of the length
L.sub.1 having a long axial length and the portion 23 of the length
L.sub.2 having a short axial length. It is needless to say that the
axial length does not have an absolutely long-and-short
relationship and has a relatively long-and-short relationship
between the portions 22 and 23. Due to the structure, the ring body
has an interleaf-like shape sandwiched between the portion of the
length L.sub.1 having a long axial length and the portion of the
length L.sub.2 having a short axial length of the elastic body
21.
[0030] As another embodiment, in order to facilitate the assembling
work to the mounting groove 24, the annular second member 41 may be
provided with a cut portion or the like in one place on the
circumference. Moreover, the second member 41 may be buried in the
elastic body 21 by carrying out insert molding in the vulcanization
molding of the elastic body 21 by a mold. Considering the function
or the like thereof, the second member 41 is also referred to as a
resistance member or also referred to as an elastic body clamping
member.
[0031] The outer diameter of the second member 41 is formed to be
larger than the outer diameter of the elastic body 21. Therefore,
the second member 41 is projected radially outward from the outer
peripheral surface of the elastic body 21.
[0032] The outer diameter of the second member 41 is formed to be
smaller than the inner diameter of the side wall 54 of the rack
housing 51. Therefore, a radial clearance c.sub.1 is formed between
the second member 41 and the side wall 54. However, the second
member 41 does not expand, and therefore it may be also structured
so that the outer diameter of the second member 41 is set to be
equal to the inner diameter of the side wall 54 so that the second
member 41 is brought into contact with the side wall 54.
[0033] The outer diameter of the elastic body 21 is formed to be
smaller than the inner diameter of the side wall 54 of the rack
housing 51, and therefore radial clearances c.sub.2 are formed
between the elastic body 21 and the side wall 54.
[0034] In the damping stopper 11 of this embodiment, when the rack
61 is displaced in the direction of approaching the rack housing 51
(arrow D) so that the interval between the end surfaces 52 and 62
decreases, the elastic body 21 is axially compressed between the
rack housing 51 and the rack 61 and expands radially outward
corresponding to the compression. The second member 41 is attached
to one axial part of the outer periphery of the elastic body 21,
and therefore acts as a resistance element to the expansion of the
elastic body 21. As a result, the radially outward expansion of the
elastic body 21 is restricted in the one axial part.
[0035] As described above, the elastic body 21 is divided into the
portion 22 of the length L.sub.1 having a long axial length and the
portion 23 of the length L.sub.2 having a short axial length. The
elastic body 21 expands in both the portions 22 and 23.
[0036] When the portion 22 of the length L.sub.1 having a long
axial length and the portion 23 of the length L.sub.2 having a
short axial length are compared, the portion 22 of the length
L.sub.1 has a surface area larger than that of the portion 23 of
the length L.sub.2 and more greatly extends radially outward than
the portion 23 of the length L.sub.2. As a result, the portion 22
of the length L.sub.1 contacts the side wall 54 earlier than the
portion 23 of the length L.sub.2 as illustrated in FIG. 2. Then, a
situation is realized in which the portion 23 of the length L.sub.2
does not yet contact the side wall 54 even when expanding in a
state where the portion 22 of the length L.sub.1 expands and
contacts the side wall 54.
[0037] Accordingly, the rise (increase) of the reaction force after
the contact becomes slow as illustrated in a graph of FIG. 3.
Therefore, the displacement amount until the allowable reaction
force is reached increases, and thus efficient energy absorption is
enabled and the absorbable energy amount can be increased.
[0038] In the graph of FIG. 3, Comparative Example illustrates a
damping stopper of a conventional structure not having the second
member 41 and the reaction force sharply rises after contact in
Comparative Example, and therefore the displacement amount is
small. A point E indicates the timing when the elastic body 21
contacts the side wall 54.
Second Embodiment
[0039] A second embodiment is described based on FIG. 4 and FIG. 5.
The same portions as those of the first embodiment are designated
by the same reference numerals and a description thereof is
omitted.
[0040] As illustrated in FIG. 4, a damping stopper 11 has an
elastic body 21 axially compressed between an end surface 52 of a
rack housing 51 and an end surface 62 of a rack 61.
[0041] The elastic body 21 is formed into an annular shape by a
predetermined rubber material. To one axial end (upper side in the
figure, the rack 61 side) and the inner peripheral surface, a metal
attachment ring 31 presenting an L-shaped cross section is bonded
(vulcanized and bonded). When the rack 61 is displaced in the
direction of approaching the rack housing 51 so that the interval
between the end surfaces 52 and 62 decreases, the elastic body 21
is axially compressed by the rack housing 51 and the rack 61 and
expands radially outward.
[0042] In the implementation of the disclosure, a metal attachment
ring (not illustrated) may be bonded also to the other axial end
(lower side in the figure, the rack housing 51 side) of the elastic
body 21.
[0043] The damping stopper 11 has a second member 41 attached to
one axial part of the outer periphery of the elastic body 21 and
restricting the expansion of the elastic body 21 in the one axial
part. More specifically, the second member 41 is attached to the
outer periphery of the elastic body 21 in one axial region of the
elastic body 21 and suppresses the expansion of the elastic body 21
in the one region.
[0044] The second member 41 is a ring body having elasticity such
that the second member 41 expands radially outward when pressed by
the elastic body 21 expanding radially outward and rigidity higher
than that of the elastic body 21 such that the second member 41
contacts a side wall 54 earlier than the elastic body 21. The ring
body having such a characteristic has rigidity higher than that of
the elastic body 21 by being formed of a material different from
that of the elastic body 21. As an example, the second member 41 is
formed of urethane.
[0045] As another embodiment, in order to facilitate the assembling
work to a mounting groove 24, the ring body configuring the second
member 41 may be provided with a cut portion in one place on the
circumference. Alternatively, the ring body may be divided into two
parts on the circumference to have a halved structure. Considering
the function or the like thereof, the second member 41 is also
referred to as a resistance member or also referred to as an
elastic body clamping member.
[0046] The outer diameter of the second member 41 is formed to be
larger than the outer diameter of the elastic body 21. Therefore,
the second member 41 is projected radially outward from the outer
peripheral surface of the elastic body 21.
[0047] The outer diameter of the second member 41 is formed to be
smaller than the inner diameter of the side wall 54 of the rack
housing 51. Therefore, a radial clearance c.sub.1 is formed between
the second member 41 and the side wall 54.
[0048] The outer diameter of the elastic body 21 is formed to be
smaller than the inner diameter of the side wall 54 of the rack
housing 51. Therefore, radial clearances c.sub.2 are formed between
the elastic body 21 and the side wall part 54.
[0049] In the damping stopper 11 of this embodiment, when the rack
61 is displaced in the direction of approaching the rack housing 51
so that the interval between the end surfaces 52 and 62 decreases,
the elastic body 21 is axially compressed between the rack housing
51 and the rack 61 and expands radially outward corresponding to
the compression. The second member 41 is attached to one axial part
of the outer periphery of the elastic body 21, and therefore acts
as a resistance element to the expansion. As a result, the radially
outward expansion of the elastic body 21 is restricted in the one
axial part.
[0050] When the elastic body 21 continuously expands in response to
a load accompanying the displacement of the rack 61, the pressure
by the expansion presses the second member 41 radially outward and
expands the second member 41 radially outward (diameter enlarging
deformation) to bring the second member 41 into contact with the
side wall 54. In order to expand the second member 41 radially
outward to bring the second member 41 into contact with the side
wall 54, a large load is required. Therefore, the rigidity of the
entire damping stopper 11 is increased, so that a high reaction
force as compared with that in the case where the elastic body 21
is used alone is generated
[0051] Thereafter, when the rack 61 is displaced in the direction
of further approaching the rack housing 51 in the state where the
second member 41 contacts the side wall 54, the second member 41
slides against the side wall 54, so that sliding resistance is
generated between the second member 41 and the side wall 54. The
rigidity is increased by the sliding resistance, so that a higher
reaction force is generated.
[0052] As illustrated in a graph of FIG. 5, according to the
damping stopper 11 of this embodiment, a sharp rise (increase) of
the reaction force is already started at the timing (point F) when
the second member 41 contacts the side wall 54. Thus, efficient
energy absorption is enabled and the absorbable energy amount can
be increased.
[0053] In the graph of FIG. 5, Comparative Example illustrates the
characteristic by a damping stopper not having the second member
41. In Comparative Example, a sharp rise (increase) of the reaction
force is started at the timing (point E) where the elastic body 21
contacts the side wall 54. Therefore, efficient energy absorption
cannot be performed and the absorbable energy amount cannot be
increased.
* * * * *