U.S. patent application number 15/937468 was filed with the patent office on 2018-08-02 for coil spring for suspension.
This patent application is currently assigned to NHK SPRING CO., LTD.. The applicant listed for this patent is NHK SPRING CO., LTD.. Invention is credited to Shusaku HAYASHI, Shuji OHMURA, Ken OKURA.
Application Number | 20180215227 15/937468 |
Document ID | / |
Family ID | 58423589 |
Filed Date | 2018-08-02 |
United States Patent
Application |
20180215227 |
Kind Code |
A1 |
OKURA; Ken ; et al. |
August 2, 2018 |
COIL SPRING FOR SUSPENSION
Abstract
A coil spring includes a wire formed of spring steel shaped to
be helical, and is compressed between an upper spring seat and a
lower spring seat. The coil spring includes an upper portion and a
lower portion. A positive pitch winding end portion is formed on
the upper portion of the coil spring. A
terminal-point-strong-abutting-portion is formed at a distal end of
the winding end portion. The terminal-point-strong-abutting-portion
is in contact with the upper spring seat at one point at a position
deviated to an inner side of a vehicle with respect to a coil
central axis. On the lower portion of the coil spring, an end turn
portion which contacts the lower spring seat is formed at a
position deviated to an outer side of the vehicle.
Inventors: |
OKURA; Ken; (Yokohama-shi,
JP) ; OHMURA; Shuji; (Yokohama-shi, JP) ;
HAYASHI; Shusaku; (Yokohama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NHK SPRING CO., LTD. |
Yokohama-shi |
|
JP |
|
|
Assignee: |
NHK SPRING CO., LTD.
Yokohama-shi
JP
|
Family ID: |
58423589 |
Appl. No.: |
15/937468 |
Filed: |
March 27, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/JP2016/078908 |
Sep 29, 2016 |
|
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15937468 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16F 1/123 20130101;
F16F 2224/0208 20130101; B60G 2204/1242 20130101; F16F 2230/0005
20130101; B60G 2206/72 20130101; B60G 2202/12 20130101; F16F 1/06
20130101; F16F 2230/0023 20130101; B60G 2202/312 20130101; B60G
2206/426 20130101; F16F 1/126 20130101; B60G 11/16 20130101; B60G
2206/71 20130101; B60G 15/07 20130101; B60G 15/063 20130101 |
International
Class: |
B60G 11/16 20060101
B60G011/16; F16F 1/12 20060101 F16F001/12; F16F 1/06 20060101
F16F001/06 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 1, 2015 |
JP |
2015-196036 |
Claims
1. A suspension coil spring which is formed of a helically wound
wire, and is compressed between an upper spring seat and a lower
spring seat, the suspension coil spring comprising: a winding end
portion of a positive pitch provided at an upper portion of the
wire, a terminal-point-strong-abutting-portion provided at a distal
end of the winding end portion, the
terminal-point-strong-abutting-portion contacting the upper spring
seat at one point at a position deviated away from a coil central
axis in a radial direction of the coil; and an end turn portion
provided at a lower portion of the wire, the end turn portion
contacting the lower spring seat at a position deviated to a side
opposite to a side that the
terminal-point-strong-abutting-portion.
2. The suspension coil spring of claim 1, wherein the
terminal-point-strong-abutting-portion contacts the upper spring
seat at a position deviated to an inner side of a vehicle with
respect to the coil central axis.
3. The suspension coil spring of claim 1, wherein the positive
pitch winding end portion has a pitch angle which allows a region
extending to 0.4 turns from a distal end of the wire to contact the
upper spring seat in a state where a load is applied.
4. The suspension coil spring of claim 2, wherein the positive
pitch winding end portion has a pitch angle which allows a region
extending to 0.4 turns from a distal end of the wire to contact the
upper spring seat in a state where a load is applied.
5. The suspension coil spring of claim 1, wherein a protection tip
is provided on the terminal-point-strong-abutting-portion, and the
upper spring seat with which the protection tip comes into contact
comprises a receiving portion.
6. The suspension coil spring of claim 2, wherein a protection tip
is provided on the terminal-point-strong-abutting-portion, and the
upper spring seat with which the protection tip comes into contact
comprises a receiving portion.
7. The suspension coil spring of claim 2, wherein the end turn
portion is formed at a position deviated to an outer side of the
vehicle, and that the end turn portion has a negative pitch in a
state where no compressive load is applied, and is deformed to have
a positive pitch by being pressed by the lower spring seat in a
state where a load is applied.
8. The suspension coil spring of claim 3, wherein the end turn
portion is formed at a position deviated to an outer side of the
vehicle, and that the end turn portion has a negative pitch in a
state where no compressive load is applied, and is deformed to have
a positive pitch by being pressed by the lower spring seat in a
state where a load is applied.
9. The suspension coil spring of claim 4, wherein the end turn
portion is formed at a position deviated to an outer side of the
vehicle, and that the end turn portion has a negative pitch in a
state where no compressive load is applied, and is deformed to have
a positive pitch by being pressed by the lower spring seat in a
state where a load is applied.
10. The suspension coil spring of claim 5, wherein the end turn
portion is formed at a position deviated to an outer side of the
vehicle, and that the end turn portion has a negative pitch in a
state where no compressive load is applied, and is deformed to have
a positive pitch by being pressed by the lower spring seat in a
state where a load is applied.
11. The suspension coil spring of claim 6, wherein the end turn
portion is formed at a position deviated to an outer side of the
vehicle, and that the end turn portion has a negative pitch in a
state where no compressive load is applied, and is deformed to have
a positive pitch by being pressed by the lower spring seat in a
state where a load is applied.
12. A suspension coil spring which is formed of a helically wound
wire, and is compressed between an upper spring seat and a lower
spring seat, the suspension coil spring comprising: a winding end
portion of a positive pitch provided at a lower portion of the
wire, a terminal-point-strong-abutting-portion provided at a distal
end of the winding end portion, the
terminal-point-strong-abutting-portion contacting the lower spring
seat at one point at a position deviated to an outer side of a
vehicle with respect to a coil central axis; and an end turn
portion provided at an upper portion of the wire, the end turn
portion contacting the upper spring seat at a position deviated to
an inner side of the vehicle.
13. The suspension coil spring of claim 12, wherein a protection
tip is provided on the terminal-point-strong-abutting-portion, and
the lower spring seat with which the protection tip comes into
contact comprises a receiving portion.
14. The suspension coil spring of claim 12, wherein the positive
pitch winding end portion has a pitch angle which allows a region
extending to 0.4 turns from a lower end of the wire to contact the
lower sprint seat in a state where a load is applied
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation Application of PCT
Application No. PCT/JP2016/078908, filed Sep. 29, 2016 and based
upon and claiming the benefit of priority from prior Japanese
Patent Application No. 2015-196036, filed Oct. 1, 2015, the entire
contents of all of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention relates to a suspension coil spring
used in a suspension mechanism of a vehicle such as a car.
2. Description of the Related Art
[0003] The suspension mechanism of a vehicle such as a car
comprises, for example, a suspension coil spring (hereinafter
simply referred. to as a coil spring) , an upper spring seat, and a
lower spring seat. The upper spring seat is disposed on the upper
side of the coil spring. The lower spring seat is disposed on the
lower side of the coil spring. The coil spring is compressed
between the upper spring seat and the lower spring seat. The coil
spring extends and retracts in accordance with the magnitude of a
load.
[0004] As an example of the suspension mechanism, a
McPherson-strut-type suspension mechanism is known. The
McPherson-strut-type suspension mechanism includes a coil spring,
and a strut (a shock absorber). The coil spring is arranged
between. the upper spring seat and the lower spring seat. The strut
is arranged inside the coil spring. Further, the coil spring
extends and retracts in accordance with. the magnitude of the load,
and the strut also expands and contracts.
[0005] In the McPherson-strut-type suspension mechanism, a central
axis of the strut is displaced from a line of action of force
input, which is obtained by connecting a ground contact point of a
tire and a strut upper end, at an angle. Accordingly, it is known
that a lateral force (a component of force which bends the strut)
affects the strut, and this lateral force increases the sliding
resistance of the strut. Patent Literatures 1 to 6 stated below
disclose means for reducing the sliding resistance of the strut. In
the well-known technology, a force line position of the coil spring
is made parallel with the line of action of force input as much as
possible, so that a lateral force produced on the strut is reduced.
In the specification, the force line position may be referred to as
a load axis.
[0006] In Patent Literature 1 (JP S58-32970 Y), d diameter an end
turn portion on a lower side of a coil spring is made smaller than
a coil diameter of an effective portion, and the effective portion
of the coil spring is arranged at a position offset to an outer
side of a vehicle relative to a central axis of a strut. However,
since the effective portion of the coil spring is offset to the
outer side of the vehicle relative to the central axis of the
strut, a space needed to arrange a suspension mechanism including
the coil spring in a vehicle body becomes large.
[0007] In Patent Literature 2 (EP 728602 A1), by bending a wire at
places near an upper end and a lower end of a coil spring,
projections which contact a lower spring seat and an upper spring
seat, respectively, are formed on the end portions of the coil
spring. A portion extending from each of the projections to the
corresponding end of the wire is treated as a bent portion of a
negative pitch (minus pitch). However, a terminal of the wire is a
portion which cannot function as a spring. Accordingly, the mass of
the coil spring is increased because of the bent portion that is
provided.
[0008] In Patent Literature 3 (JP 3515957 B), a pitch angle of an
effective portion of the coil spring is changed in accordance with
the position of turns from an end for each turn of the wire. In
this coil spring, by applying a load transversely (i.e., in a
radial direction of a coil) in a usage state in which the coil
spring is fitted to a suspension mechanism, an initial lateral
force and a moment are produced. Further, in this state, by firmly
holding both ends of the coil spring to an upper spring seat and a
lower spring seat, respectively, the coil spring is compressed
while maintaining this state. For this reason, with respect to the
coil spring of Patent Literature 3, a preload needs to be applied
transversely (the radial direction of the coil) when it is fitted
to the suspension mechanism. Consequently, fitting of the coil
spring to the suspension mechanism is not easy. Moreover, since an
end turn portion which does not function as a spring exists in each
of the both ends of the coil spring, the mass of the coil spring is
increased by these end turn portions.
[0009] In Patent Literature 4 (JP 4336203 B) , a plurality of
projections are formed on an end turn portion of a coil spring, and
the wire made to contact different projections according to a load
applied to the coil spring. For example, in accordance with
increase of the load, the projection on the farther side from an
end of the wire contacts the spring seat. Accordingly, when a load
applied to the coil spring is changed, a position of contact
between the end turn portion and the spring seat is changed.
Therefore, a force line position (load axis) is also changed.
[0010] In a coil spring of Patent Literature 5 (JP 2013-173536 A) ,
the coil spring is arranged offset to an outer side of a vehicle
with respect to a central axis of a strut. Accordingly, a space
needed for arranging a suspension mechanism including the coil
spring in a vehicle body is increased.
[0011] In a coil spring of Patent Literature 6 (JP 2014-237431 A),
an end turn portion of a negative pitch (a reverse pitch), which
does not function as a spring, is provided on each of the upper end
and lower end of the coil spring. Accordingly, the mass of the coil
spring is increased by the above negative pitch end turn
portions.
[0012] Depending on a vehicle, there may be a case where the force
line position (load axis) of the coil spring is desired to be
inclined in an aimed direction with respect to the coil central
axis also in a suspension mechanism other than the
McPherson-strut-type suspension mechanism.
BRIEF SUMMARY OF THE INVENTION
[0013] Accordingly, an object of the present invention is to
provide a suspension coil spring whose force line position can be
inclined in a desired direction with respect to the coil central
axis, and whose weight can be reduced.
[0014] One embodiment of the present invention relates to a
suspension coil spring which is formed of a helically wound wire,
and is compressed between an upper spring seat and a lower spring
seat, in which the suspension coil spring includes: a winding end
portion of a positive pitch at an upper portion of the wire, and a
terminal-point-strong-abutting-portion, which contacts the upper
spring seat at one point at a position deviated away from a coil
central axis in a radial direction of the coil, at a distal end of
the winding end portion. Further, the suspension coil spring
includes an end turn portion, which contacts the lower spring seat
at a position opposite to the
terminal-point-strong-abutting-portion (for example, an outer side
of a vehicle), at a lower portion of the wire.
[0015] According to this embodiment, it is possible to incline the
force line position of the suspension coil spring in a direction
desired for the suspension mechanism. For example, in the case of a
McPherson-strut-type suspension mechanism, since the force line
position of the coil spring can be made parallel with the line of
action of load input, a lateral force and a bending moment produced
on the strut can be reduced. Also, an end turn portion, which does
not function as a spring, can be eliminated in at least one of the
upper part and the lower part of the coil spring (i.e., the part
provided with the terminal-point-strong-abutting-portion), whereby
weight reduction is enabled.
[0016] In this embodiment, the
terminal-point-strong-abutting-portion may contact the upper spring
seat at a position deviated to an inner side of the vehicle with
respect to the coil central axis. In order to protect the spring
seat, etc., the positive pitch winding end portion may have a pitch
angle which allows a region extending to 0.4 turns from a distal
end of the wire (the terminal-point-strong-abutting-portion) to
contact the upper spring seat in a state in which a load is
applied. Also, the terminal-point-strong-abutting-portion may be
provided with a protection tip, and the upper spring seat with
which the protection tip comes into contact may comprise a
receiving portion such as a wear-resistant portion. Further, the
embodiment may be structured such that the end turn portion is
formed at a position deviated to the outer side of the vehicle, and
that the end turn portion has a negative pitch when no compressive
load is applied, and is deformed to have a positive pitch by being
pressed by the lower spring seat when a load is applied.
[0017] In another embodiment, a winding end portion of a positive
pitch is provided at a lower portion of the wire, a
terminal-point-strong-abutting-portion, which contacts the lower
spring seat at one point at a position deviated to the outer side
of the vehicle with respect to the coil central axis, is provided
at a distal end of the winding end portion, and an end turn
portion, which contacts the upper spring seat at a position
deviated to the inner side of the vehicle, is provided at the upper
portion of the wire.
[0018] Additional objects and advantages of the invention will be
set forth in the description which follows, and in part will be
obvious from the description, or may be learned by practice of the
invention. The objects and advantages of the invention may be
realized and obtained by means of the instrumentalities and
combinations particularly pointed out hereinafter.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0019] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate embodiments of
the invention, and together with the general description given
above and the detailed description of the embodiments given below,
serve to explain the principles of the invention.
[0020] FIG. 1 is a vertical cross-sectional view of a suspension
mechanism according to a first embodiment.
[0021] FIG. 2 is a perspective view of a coil spring of the
suspension mechanism shown in FIG. 1.
[0022] FIG. 3 is a side view showing a
terminal-point-strong-abutting-portion of a coil spring according
to a second embodiment.
[0023] FIG. 4 is a side view showing a
terminal-point-strong-abutting-portion of a coil spring according
to a third embodiment.
[0024] FIG. 5 is a side view showing a lower part of a coil spring
according to a fourth embodiment.
[0025] FIG. 6 is a side view schematically showing a state in which
the coil spring shown in FIG. 5 is compressed between an upper
spring seat and a lower spring seat. FIG. 7 is a vertical
cross-sectional view of a suspension mechanism according to a fifth
embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0026] A suspension coil spring according to a first embodiment
will now be described with reference to FIGS. 1 and 2.
[0027] FIG. 1 shows a McPherson-strut-type suspension mechanism 11
provided in a vehicle body 10 (partly shown), which is an example
of a suspension mechanism for vehicles. The suspension mechanism 11
comprises a coil spring (a compression coil spring) 12, an upper
spring seat 13, a lower spring seat 14, a shock absorber 15 which
functions as a strut, a mount member 16, a bracket 18, etc. The
upper spring seat 13 is disposed on the upper side of the coil
spring 12. The lower spring seat 14 is disposed on the lower side
of the coil spring 12. An upper end of the shock absorber 15 is
mounted on the vehicle body 10 by the mount member 16. A knuckle
member 17 is fixed to the bracket 18. The shock absorber 15
includes a cylinder 15a and a rod 15b. An axis X.sub.S of the shock
absorber 15 is inclined by angle .theta.1 with respect to a
vertical line H extending vertically.
[0028] As shown in FIG. 1, the coil spring 12 is fitted onto the
vehicle body 10 in such a state that it is compressed between the
upper spring seat 13 and the lower spring seat 14 (i.e., a state in
which a preload is applied). The coil spring 12 elastically
supports the compressive load applied from above the vehicle 10.
The coil spring 12 and the shock absorber 15 are extended and
retracted between a full bump (the maximum compression state) and a
full rebound (the maximum expansion state) in accordance with the
magnitude of the load.
[0029] A load applied from above the suspension mechanism 11 is
supported by a wheel (a tire) via the knuckle member 17. A line of
action of load input L1 forms an angle of .theta.2 to a
vehicle-outer-side V.sub.out with respect to the axis X.sub.S of
the shock absorber 15 in light of the relationship with a ground
contact point, of the tire. A lateral force is produced on the
shock absorber 15 by this angle .theta.2. Since the lateral force
becomes a cause of increasing friction of the shock absorber 15, it
is desired to reduce the lateral force.
[0030] FIG. 2 schematically illustrates the coil spring 12 arranged
between the upper spring seat 13 and the lower spring seat 14. The
coil spring 12 is mounted on the vehicle body 10 in an assembly
state of being compressed between the upper spring seat 13 and the
lower spring seat 14. When a compressive load P is applied in a
direction along a coil central axis X1, the coil spring 12 is
deformed in a direction of making the length of the coil spring 12
shorter than the free length (i.e., the length in a state where no
load is applied).
[0031] An example of the coil spring 12 is formed of an element (a
wire 30) made of spring steel having a circular cross section. The
wire 30 is formed in a helical shape. An example of the coil spring
12 is a cylindrical coil spring. However, depending on the
specification of a vehicle, various forms of compression coil
springs, such as a barrel-shaped coil spring, an hourglass coil
spring, a tapered coil spring, a variable pitch coil spring, and
the other shaped springs, can be adopted. A coating film for rust
prevention is formed on the entire outer surface of the wire
30.
[0032] The wire 30 of the coil spring 12 includes an upper portion
12a and a lower portion 12b. A coil body portion 12c wound
helically at a pitch angle e is formed between the upper portion
12a and the lower portion 12b. The pitch angle .alpha. may be
varied in the direction along the coil central axis X1.
Alternatively, the pitch angle .alpha. may be substantially
constant in the direction along the coil central axis X1. The coil
central axis X1 passes through substantially the center of the coil
body portion 12c.
[0033] At the upper portion 12a of the coil spring 12, a winding
end portion 31 of a positive pitch (i.e., a positive pitch angle
.alpha.1 as shown in FIG. 2) is formed. A
terminal-point-strong-abutting-portion 35 is formed at a distal end
(an upper end) of the winding end portion 31. The
terminal-point-strong-abutting-portion 35 contacts the upper spring
seat 13 at one point. In other words, the
terminal-point-strong-abutting-portion 35 is in contact with the
upper spring seat 13 at a position deviated away from the coil
central axis X1 in a radial direction of the coil, more
specifically, to a vehicle-inner-side V.sub.in, by a distance Y1.
At a contact portion of the upper spring seat 13 and the
terminal-point-strong-abutting-portion 35, a wear-resistant force
transmission portion 37 (FIG. 1) should preferably be provided.
[0034] An end turn portion 40 is formed at the lower portion 12b of
the coil spring 12. The number of turns of the end turn portion 40
is, for example, 0.5 or so. The end turn portion 40 is in contact
with the lower spring seat 14 at a position deviated to the
vehicle-outer-side V.sub.out with respect to the coil central axis
X1. More specifically, the end turn portion 40 includes a first
portion 40a and a second portion 40b. The first portion 40a is
always in contact with the spring seat 14 irrespective of the
magnitude of the load P. Thus, the first portion 40a is a portion
(non-effective portion) which does not function as a spring. The
second portion 40b is separated from the spring seat 14 when the
load P is small, and contacts the spring seat 14 when it is
large.
[0035] The coil spring 12 of the present embodiment is compressed
between. the terminal-point-strong-abutting-portion 35 and the end
turn portion 40. The terminal-point-strong-abutting-portion 35
contacts the upper spring seat 13 at a position deviated to the
vehicle-inner-side V.sub.in. The end turn portion 40 contacts the
lower spring seat 14 at a position deviated to the
vehicle-outer-side V.sub.out. Consequently, a force line position
FLP is inclined in a direction along the line of action of force
input Li (FIG. 1) at an angle of .theta.3 (FIG. 2) with respect to
the coil central axis X1. The force line position FLP is a center
line of a repulsive load of the coil spring 12. Since the force
line position FLP is inclined in the direction along the line of
action of force input L1, a component of force directed to the
vehicle-outer-side V.sub.out is produced at an upper end of the
coil spring 12. The component of force is effective in canceling a
bending moment which is produced on the shock absorber 15.
[0036] Moreover, in the coil spring 12 of the present embodiment,
the upper portion 12a contacts the upper spring seat 13 via the
terminal-point-strong-abutting-portion 35. For this reason, an end
turn portion (i.e., a portion which does not function as a spring)
is not required in the upper portion 12a of the coil spring 12.
More specifically, with respect to the coil spring 12 of the
present embodiment, almost the entire length of the coil spring 12
excluding the lower end turn portion 40 can be used as an effective
portion of the spring. Thus, the mass can be reduced as compared to
a conventional spring having an end turn portion on each of an
upper end and a lower end. Note that when the compressive load P is
increased, the wire can be brought into intimate contact for a
certain length from the terminal-point-strong-abutting-portion 35.
Also in this case, a load is substantially concentrated on the
terminal-point-strong-abutting-portion 35.
[0037] The winding end portion 31 of the positive pitch may have
its pitch angle in the free state determined so that the spring
seat 13, etc., can be protected in a state where a compressive load
is applied to the coil spring 12. The pitch angle of the winding
end portion 31 may be determined such that a region extending to
0.4 turns from the terminal-point-strong-abutting-portion 35 at a
distal end of the wire 30, for example, contacts the spring seat
13.
[0038] FIG. 3 shows a part of a coil spring 12 according to a
second embodiment. A terminal-point-strong-abutting-portion 35 is
formed at a distal end of the coil spring 12. A protection tip 50
as an example of a force transmission portion 37 is provided at the
terminal-point-strong-abutting-portion 35. An example of the
protection tip 50 is a wear-resistant tip formed of a material
whose hardness is greater than that of a wire 30, and which is hard
to wear (for example, cemented carbide, high-speed steel, or
titanium alloy). This wear-resistant tip is arranged on a distal
end of the wire 30. Alternatively, an elastomer such as urethane,
rubber, or a polymeric material (resin) may be used for the
material of the protection tip 50.
[0039] On a surface of a spring seat 13 where the protection tip 50
contacts, a receiving portion 51 for a wear-resistant member, etc.,
is formed. The receiving portion 51 may include a solid lubricant
such as graphite. Since the other structures and functions have
commonalities with those of the coil spring 12 of the first
embodiment (FIGS. 1 and 2), common reference numbers are assigned
to parts in common with the first embodiment, and explanation of
such parts is omitted.
[0040] FIG. 4 shows a part of a coil spring 12 according to a third
embodiment. A terminal-point-strong-abutting-portion 35 is formed
at a distal end of the coil spring 12. A protection tip 50 is
provided at the terminal-point-strong-abutting-portion 35. On a
surface of a spring seat 13 where the protection tip 50 contacts, a
receiving portion 51 for a wear-resistant member, etc., is
provided. A recess 52 into which a spherical portion of the
protection tip 50 is rotatably fitted may be formed on the
receiving portion 51. Since the other structures and functions have
commonalities with those of the coil spring 12 of the second
embodiment, common reference numbers are assigned to parts in
common with the second embodiment, and explanation of such parts is
omitted.
[0041] FIG. 5 is a side view showing a part of a coil spring 12
according to a fourth embodiment. FIG. 6 is a side view
schematically showing a state in which the coil spring 12 shown in
FIG. 5 is compressed between an upper spring seat 13 and a lower
spring seat 14. A terminal-point-strong-abutting-portion 35 is
provided at an upper end of the coil spring 12. The
terminal-point-strong-abutting-portion 35 contacts the upper spring
seat 13 at one point at a position deviated to a vehicle-inner-side
V.sub.in with respect to a coil central axis X1.
[0042] As shown in FIG. 5, an end turn portion 55 is formed at the
lower part of the coil spring 12. The end turn portion 55 has a
negative pitch in the free state in which no load is applied. The
end turn portion 55 of the negative pitch forms a negative angle
(-.alpha.) with respect to a line segment L2 orthogonal to the coil
central axis X1. A portion excluding the end turn portion 55 has a
positive pitch of pitch angle .alpha.2. The end turn portion 55 on
the lower side is supported at a position deviated to a
vehicle-outer-side V.sub.out with respect to the coil central axis
X1 by a supporting surface 14a of the lower spring seat 14, as
shown in FIG. 6. The supporting surface 14a of the lower spring
seat 14 forms a positive inclination angle .beta.. When the coil
spring 12 is compressed between the spring seats 13 and 14 by a
load P, the end turn portion 55 is elastically deformed in the
positive pitch at a glance, in accordance with the inclination
angle .beta. of the supporting surface 14a. Also with the coil
spring 12 as described above, a force line position (a load axis)
FLP can be inclined in a direction along a line of action of force
input.
[0043] FIG. 7 shows a suspension mechanism 11' according to a fifth
embodiment. At a distal end of a winding end portion 60 on the
lower part of a coil spring 12, a
terminal-point-strong-abutting-portion 35' is formed. The
terminal-point-strong-abutting-portion 35' is in contact with a
lower spring seat 14 at a position deviated to a vehicle-outer-side
V.sub.out with respect to a coil central axis. An end turn portion
61 formed at the upper part of the coil spring 12 is in contact
with an upper spring seat 13 at a position deviated to a
vehicle-inner-side V.sub.in with respect to the coil central axis.
When the distal end of the lower winding end portion 60 is directed
toward the outer side of the vehicle as in this embodiment, by
forming the terminal-point-strong-abutting-portion 35' on the
distal end of the winding end portion 60, a force line position (a
load axis) can be inclined in a desired direction.
[0044] The winding end portion 60 of a positive pitch may have its
pitch angle in the free state determined so that the spring seat
14, etc., can be protected in a state where a compressive load is
applied to the coil spring 12. The pitch angle of the winding end
portion 60 may be determined such that a region extending to 0.4
turns from the terminal-point-strong-abutting-portion 35' at a
lower end of a wire 30, for example, contacts the spring seat 14. A
protection tip 50 and a receiving portion 51 shown in FIG. 3 or
FIG. 4 may be provided at the
terminal-point-strong-abutting-portion 35'.
[0045] According to the suspension mechanism 11' shown in. FIG. 7,
the lower part of the coil spring 12 is supported by the lower
spring seat 14 via the terminal-point-strong-abutting-portion 35'.
Accordingly, there is no need to provide an end turn portion on the
lower part of the coil spring 12. According to this structure, it
is possible to avoid the risk of the coil spring being damaged by
hard foreign substances such as sand being trapped between the
lower spring seat and the end turn portion. Since the other
structures and functions have commonalities with those of the
suspension mechanism 11 of the first embodiment (FIGS. 1 and 2),
common reference numbers are assigned to parts in common with the
first embodiment, and explanation of such parts is omitted.
[0046] Depending on the specification of a suspension, a lateral
force may be produced when the force line position (load axis) of
the coil spring is inclined in a longitudinal direction of the
vehicle. When this lateral force affects the vehicle performance,
the lateral force may be canceled by arranging the
terminal-point-strong-abutting-portion such that the force line
position comes to a neutral position in the longitudinal
direction.
[0047] Needless to say, in carrying out the present invention, not
only the specific shape and arrangement of the coil spring, but
also the position and shape of the
terminal-point-strong-abutting-portion, and the shape, arrangement,
etc., of the upper spring seat and the lower spring seat which
constitute the suspension system may be modified variously. The
present invention can be applied to a suspension mechanism of a
vehicle other than cars. Also, the present invention can be applied
to a coil spring of a suspension system other than the
McPherson-strut-type suspension.
[0048] Additional advantages and modifications will readily occur
to those skilled in the art. Therefore, the invention in its
broader aspects is not limited to the specific details and
representative embodiments shown and described herein. Accordingly,
various modifications may be made without departing from the spirit
or scope of the general inventive concept as defined by the
appended claims and their equivalents.
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