U.S. patent number RE43,989 [Application Number 12/784,111] was granted by the patent office on 2013-02-12 for load cell attachment structure.
This patent grant is currently assigned to Honda Motor Co., Ltd., TS Tech Co., Ltd.. The grantee listed for this patent is Shigeru Endo, Takashi Furukawa, Mikihito Kojima, Naotaka Kumakiri, Harutomi Nishide, Kenji Sato, Toyohiko Shindo, Tatsuya Yamazaki, Masashi Yoshifuku. Invention is credited to Shigeru Endo, Takashi Furukawa, Mikihito Kojima, Naotaka Kumakiri, Harutomi Nishide, Kenji Sato, Toyohiko Shindo, Tatsuya Yamazaki, Masashi Yoshifuku.
United States Patent |
RE43,989 |
Furukawa , et al. |
February 12, 2013 |
Load cell attachment structure
Abstract
This load cell attachment structure includes a male screw which
is formed on a load sensing part of the load cell, a nut which
attaches the load cell to the attachment plate by engaging with the
male screw, and a wave washer which is disposed between the
attachment plate and the nut.
Inventors: |
Furukawa; Takashi (Utsunomiya,
JP), Kumakiri; Naotaka (Utsunomiya, JP),
Kojima; Mikihito (Utsunomiya, JP), Yoshifuku;
Masashi (Utsunomiya, JP), Yamazaki; Tatsuya
(Dublin, OH), Shindo; Toyohiko (Tochigi, JP),
Nishide; Harutomi (Utsunomiya, JP), Endo; Shigeru
(Tochigi, JP), Sato; Kenji (Sakura, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Furukawa; Takashi
Kumakiri; Naotaka
Kojima; Mikihito
Yoshifuku; Masashi
Yamazaki; Tatsuya
Shindo; Toyohiko
Nishide; Harutomi
Endo; Shigeru
Sato; Kenji |
Utsunomiya
Utsunomiya
Utsunomiya
Utsunomiya
Dublin
Tochigi
Utsunomiya
Tochigi
Sakura |
N/A
N/A
N/A
N/A
OH
N/A
N/A
N/A
N/A |
JP
JP
JP
JP
US
JP
JP
JP
JP |
|
|
Assignee: |
Honda Motor Co., Ltd. (Tokyo,
JP)
TS Tech Co., Ltd. (Asaka-shi, JP)
|
Family
ID: |
35994873 |
Appl.
No.: |
12/784,111 |
Filed: |
May 20, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
11219213 |
Sep 2, 2005 |
7373846 |
May 20, 2008 |
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Foreign Application Priority Data
|
|
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|
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Sep 7, 2004 [JP] |
|
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2004-259502 |
Sep 7, 2004 [JP] |
|
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2004-259503 |
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Current U.S.
Class: |
73/862.621;
73/862.622; 177/187; 73/862.632; 177/136; 177/144; 177/189 |
Current CPC
Class: |
G01N
3/02 (20130101); G01N 2203/0676 (20130101) |
Current International
Class: |
G01L
1/26 (20060101); G01G 19/08 (20060101); G01G
19/52 (20060101) |
Field of
Search: |
;73/862.621 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Abstract of JP2001187911. cited by examiner .
Abstract of JP9229036. cited by examiner.
|
Primary Examiner: Caputo; Lisa
Assistant Examiner: Roy; Punam
Attorney, Agent or Firm: Rankin, Hill & Clark LLP
Claims
What is claimed is:
1. A load cell attachment structure for attaching a load cell to an
attachment plate, .Iadd.the load cell including a main body and a
load sensing part, the load cell attachment structure
.Iaddend.comprising: a first fastening part which is formed on .[.a
load sensing part.]. .Iadd.the main body .Iaddend.of the load cell;
a second fastening part which attaches the load cell to the
attachment plate by engaging with the first fastening part; an
elastic body which is disposed between the attachment plate and the
second fastening part; and a washer part which entirely covers the
load sensing part, and is disposed between the attachment plate and
the load sensing part.
2. A load cell attachment structure according to claim 1, further
comprising: a collar part which is disposed between the washer part
and the second fastening part, wherein a length of the collar part
along an axis thereof is longer than a thickness of the attachment
plate.
3. A load cell attachment structure according to claim 2, wherein
the first fastening part comprises a male screw, the second
fastening part comprises a nut, the elastic body is disposed
between the attachment plate and the nut, and the collar part is
disposed between the washer part and the nut.
4. A load cell attachment structure according to claim 2, wherein
the collar part is formed as a single body with the washer
part.
5. A load cell attachment structure for attaching a load cell to an
attachment plate, .Iadd.the load cell including a main body and a
load sensing part, the load cell attachment structure
.Iaddend.comprising: a first fastening part which is formed on .[.a
load sensing part.]. .Iadd.the main body .Iaddend.of the load cell;
a second fastening part which attaches the load cell to the
attachment plate by engaging with the first fastening part; a
washer part which entirely covers the load sensing part, and is
disposed between the load sensing part and the attachment plate;
and a collar part which is disposed between the washer part and the
second fastening part, wherein a length of the collar part along an
axis thereof is longer than a thickness of the attachment
plate.
6. A load cell attachment structure according to claim 5, wherein
the first fastening part comprises a male screw, the second
fastening part comprises a nut, and the collar part is disposed
between the washer part and the nut.
7. A load cell attachment structure according to claim 5, wherein
the collar part is formed as a single body with the washer
part.
8. A load cell attachment structure for attaching a load cell to an
attachment plate, .Iadd.the load cell including a main body and a
load sensing part, the load cell attachment structure
.Iaddend.comprising: a male screw which is formed on .[.a load
sensing part.]. .Iadd.the main body .Iaddend.of the load cell and
which is inserted into an attachment hole formed in the attachment
plate; a nut which attaches the load cell to the attachment plate
by engaging with the male screw; an elastic body which is disposed
between the attachment plate and the nut fastened on the male
screw; and a washer having a washer part and a collar part and
which is disposed between the load sensing part and the attachment
plate, in which the washer part covers all of the load sensing part
and contacts the load sensing part, and the collar part is disposed
between the washer part and the nut, wherein the male screw is
inserted into the collar part, the collar part is inserted into the
attachment hole, the length of the collar part along an axis
thereof is longer than a thickness of the attachment plate to have
a space between the nut and the attachment plate, and the elastic
body having a thickness greater than the space is disposed between
the attachment plate and the nut, and the nut is engaged with the
male screw until the nut contacts the collar part.
9. A load cell attachment structure for attaching a load cell to an
attachment plate, .Iadd.the load cell including a main body and a
load sensing part, the load cell attachment structure
.Iaddend.comprising: a male screw which is formed on .[.a load
sensing part.]. .Iadd.the main body .Iaddend.of the load cell and
which is inserted into an attachment hole formed in the attachment
plate; a nut which attaches the load cell to the attachment plate
by engaging with the male screw; a plate-spring which is composed
of a flat plate part and a tapered part disposed on the outside
edge of the flat plate part and which is disposed between the
attachment plate and the nut fastened on the male screw to push the
attachment plate to the load sensing part; and.[.,.]. a washer
having a washer part and a collar part and which is disposed
between the load sensing part and the attachment plate, in which
the washer part contacts the load sensing part, and the collar part
is disposed between the washer part and the nut; wherein the flat
plate part of the plate spring is disposed between the collar part
and the nut.
10. The load cell attachment structure according to claim 9,
wherein an elastic cover is disposed on an edge of the attachment
hole.
11. The load cell attachment structure according to claim 10,
wherein a space is formed between the elastic cover and the collar
part.
12. The load cell attachment structure of claim 10, wherein the
elastic cover is disposed between the attachment plate and the
washer part.
13. The load cell attachment structure according to claim 9,
wherein a second washer is disposed between the flat plate part and
the collar part.
14. The load cell attachment structure according to claim 13,
wherein a third washer is disposed between the nut and the flat
plate part, and an outer diameter of the third washer is larger
than that of the second washer.
.Iadd.15. The load cell attachment structure according to claim 2,
wherein the elastic body is arranged at a periphery of the collar
part..Iaddend.
.Iadd.16. The load cell attachment structure according to claim 4,
wherein the elastic body is arranged at a periphery of the collar
part..Iaddend.
.Iadd.17. The load cell attachment structure according to claim 1,
wherein the washer part contacts the load sensing
part..Iaddend.
.Iadd.18. The load cell attachment structure according to claim 1,
wherein an outer edge of the elastic body is farther than a
periphery of the main body of the load cell from the first
fastening part arranged at a center of the main body..Iaddend.
.Iadd.19. The load cell attachment structure according to claim 1,
wherein the washer part is larger in diameter than the load sensing
part..Iaddend.
.Iadd.20. The load cell attachment structure according to claim 1,
wherein an outer edge of the elastic body is farther than a
periphery of the main body of the load cell from the male screw
arranged at the center of the main body..Iaddend.
.Iadd.21. The load cell attachment structure according to claim 7,
wherein the load cell warps when load downwardly acts on the load
sensing part, and thereby the load acting on the load sensing part
is measured by the load cell..Iaddend.
.Iadd.22. The load cell attachment structure according to claim 7,
further comprising an elastic body which is disposed between the
washer part and the second fastening part..Iaddend.
.Iadd.23. The load cell attachment structure according to claim 22,
wherein the elastic body includes an inclination part..Iaddend.
.Iadd.24. The load cell attachment structure according to claim 5,
wherein the washer part contacts the load sensing
part..Iaddend.
.Iadd.25. The load cell attachment structure according to claim 5,
wherein the load cell warps when a load downwardly acts on the load
sensing part, and thereby the load acting on the load sensing part
is measured by the load cell..Iaddend.
.Iadd.26. The load cell attachment structure according to claim 5,
further comprising an elastic body which is disposed between the
washer part and the second fastening part..Iaddend.
.Iadd.27. The load cell attachment structure according to claim 26,
wherein the elastic body includes an inclination part..Iaddend.
.Iadd.28. The load cell attachment structure according to claim 26,
wherein a second washer is disposed between the collar part and a
nut included in the second fastening part..Iaddend.
.Iadd.29. The load cell attachment structure according to claim 26,
wherein the elastic body includes a bending part..Iaddend.
.Iadd.30. The load cell attachment structure according to claim 26,
wherein an end of the elastic body close to the second fastening
part contacts a second washer..Iaddend.
.Iadd.31. The load cell attachment structure according to claim 26,
wherein the attachment plate includes an attachment hole to which
the first fastening part is inserted, and a cover is disposed
between a hole portion and the collar part..Iaddend.
.Iadd.32. The load cell attachment structure according to claim 31,
wherein the cover prevents the collar part from contacting an
attachment hole of an attachment plate..Iaddend.
.Iadd.33. The load cell attachment structure according to claim 31,
wherein the cover is an independent member from the elastic
body..Iaddend.
.Iadd.34. The load cell attachment structure according to claim 31,
wherein the cover comprises an insertion portion to be inserted to
the attachment hole, and an extension part outwardly-extending in a
radial direction from the insertion portion..Iaddend.
.Iadd.35. The load cell attachment structure according to claim 31,
wherein the elastic body includes a bending part..Iaddend.
.Iadd.36. The load cell attachment structure according to claim 5,
wherein a second washer is disposed between the collar part and a
nut included in the second fastening part..Iaddend.
.Iadd.37. The load cell attachment structure according to claim 5,
further comprising an elastic body which is disposed between the
attachment plate and the second fastening part, wherein the elastic
body includes a bending part..Iaddend.
.Iadd.38. The load cell attachment structure according to claim 5,
wherein the washer part is larger in diameter than the load sensing
part..Iaddend.
.Iadd.39. The load cell attachment structure according to claim 5,
further comprising an elastic body which is disposed between the
attachment plate and the second fastening part, wherein an end of
the elastic body close to the second fastening part contacts a
second washer..Iaddend.
.Iadd.40. The load cell attachment structure according to claim 5,
further comprising an elastic body which is disposed between the
attachment plate and the second fastening part, wherein the elastic
body is arranged at a periphery of the collar part..Iaddend.
.Iadd.41. The load cell attachment structure according to claim 5,
further comprising an elastic body which is disposed between the
attachment plate and the second fastening part, wherein an outer
edge of the elastic body is farther than a periphery of the main
body of the load cell from the male screw arranged at the center of
the main body..Iaddend.
.Iadd.42. The load cell attachment structure according to claim 5,
wherein the attachment plate includes an attachment hole to which
the first fastening part is inserted, and a cover is disposed
between a hole portion and the collar part..Iaddend.
.Iadd.43. The load cell attachment structure according to claim 42,
wherein the cover prevents the collar part from contacting an
attachment hole of an attachment plate..Iaddend.
.Iadd.44. The load cell attachment structure according to claim 8,
wherein the washer part contacts the load sensing
part..Iaddend.
.Iadd.45. The load cell attachment structure according to claim 8,
wherein an outer edge of the elastic body is farther than a
periphery of the main body of the load cell from the male screw
arranged at a center of the main body..Iaddend.
.Iadd.46. The load cell attachment structure according to claim 8,
wherein the elastic body is arranged at a periphery of the collar
part..Iaddend.
.Iadd.47. The load cell attachment structure according to claim 8,
wherein the washer part is larger in diameter than the load sensing
part..Iaddend.
.Iadd.48. A load cell attachment structure for attaching a load
cell to an attachment plate, the load cell including a main body
and a load sensing part, the load cell attachment structure
comprising: a first fastening part which is formed on the main body
of the load cell; a second fastening part which attaches the load
cell to the attachment plate by engaging with the first fastening
part; a washer part which entirely covers the load sensing part,
and is disposed between the load sensing part and the attachment
plate; a collar part which is disposed between the washer part and
the second fastening part; and an elastic body which is disposed
between the washer part and the second fastening part, wherein the
elastic body is arranged at a periphery of the collar part, and a
length of the collar part along an axis thereof is longer than a
thickness of the attachment plate..Iaddend.
.Iadd.49. The load cell attachment structure according to claim 48,
wherein the elastic body includes an inclination part..Iaddend.
.Iadd.50. The load cell attachment structure according to claim 48,
wherein a second washer is disposed between the collar part and a
nut included in the second fastening part..Iaddend.
.Iadd.51. The load cell attachment structure according to claim 48,
wherein the elastic body includes a bending part..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a load cell attachment
structure.
Priority is claimed on Japanese Patent Application No. 2004-259502,
filed Sep. 7, 2004, and on Japanese Patent Application No.
2004-259503, filed Sep. 7, 2004, the content of which is
incorporated herein by reference.
2. Description of Related Art
In order to control operating and the like of an air bag system
when a collision of a vehicle happens, a load cell which measures
load acting on a seat is mounted on the vehicle. Then, it is
determined whether an occupant is seated or not, and whether the
occupant who is seated is an adult or a child, and the like.
For example, there is a system which includes stud bolts projecting
above, which is disposed on the front and rear of sliders of
bilateral seat rails, a plate member which is fixed on the stud
bolts and a seat frame. One end of the plate member is fixed on a
tip of the stud bolts which go through holes of the seat frame, and
the other end of the plate member is fixed on the seat frame (refer
to U.S. Pat. No. 6,161,891). In the reference, amount of
deformation of the plate member is measured.
Also, as shown in FIG. 7, there is a system in which a male screw
102 is disposed on a load sensing part 101 of a load cell 100, the
load cell 100 is attached to a slider 103 of a seal rail facing
upward toward the load sensing part 101, and an attachment plate
104 of a seat frame is attached to the load cell 100 by engaging a
nut 105 with the male screw 102. In this system, when the
attachment plate 104 is attached to the load sensing part 101 by
fastening the nut 105 to the male screw 102 tightly, if only the
attachment plate 104 of the seat frame warps or inclines slightly
due to a minor accident of the vehicle or the like, the load cell
100 measures slight loads are caused by the warp or the incline. As
a result, the load cell 100 cannot measure loads accurately.
Accordingly, as shown in FIG. 8, it is proposed that clearance
which allows warp or the incline of the attachment plate 104 be
formed between the nut 105 and the load sensing part 101 by
disposing a collar 106 between the nut 105 and the load sensing
part 101. However, in this system, a fastening force along the
longitudinal direction of the male screw 102 acts on the load
sensing part 101 through the collar 106. As a result, the load cell
100 senses undesired load. In other words, drift force along the
axis is caused on the load cell 100.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a load cell
attachment structure capable of preventing a load cell from sensing
undesired loads which are caused by warp or a incline of the
attachment plate, and as a result, load cell can measure loads
accurately.
A load cell attachment structure of the present invention for
attaching a load cell to an attachment plate includes: a first
fastening part which is formed on a .[.load sensing part.].
.Iadd.main body .Iaddend.of the load cell; a second fastening part
which attaches the load cell to the attachment plate by engaging
with the first fastening part; and an elastic body which is
disposed between the attachment plate and the second fastening
part.
According to the present invention, since the elastic body is
disposed between the attachment plate and the second fastening
part, if the attachment plate warps or inclines, such wrap or
incline is absorbed by deformation of the elastic body. Therefore,
.Iadd.a load sensing part of .Iaddend.the load cell does not sense
an undesired load which is caused by the warp or the incline of the
attachment plate. As a result, it is possible to measure loads
which act on the load sensing part exactly.
It is preferable that the load cell attachment structure further
include a washer part which covers the load sensing part, and is
disposed between the load sensing part and the attachment plate,
and a collar part which is disposed between the washer part and the
second fastening part, wherein a length of the collar part along an
axis thereof is longer than a thickness of the attachment
plate.
According to the present invention, a clearance which absorbs the
wrap or incline of the attachment plate is appropriately formed
between the washer part and the second fastening part by the collar
part. In addition, the fastening force which is introduced through
the collar part is dispersed on the load sensing part evenly, by
the washer part. Therefore, the load cell does not sense an
undesired load which is caused by the warp or the incline of the
attachment plate, and the fastening force. As a result, it is
possible to measure loads which act on the load sensing part
exactly.
It is preferable in the load cell attachment structure of the
present invention, that the first fastening part be a male screw,
the second fastening part be a nut, the elastic body be disposed
between the attachment plate and the nut, and the collar part be
disposed between the washer part and the nut. Alternatively, it is
preferable in the load cell attachment structure of the present
invention, that the first fastening part be a female screw, the
second fastening part be a bolt, the elastic body be disposed
between the attachment plate and a top of the bolt, and the collar
part be disposed between the washer part and the top of the
bolt.
It is preferable for the load cell attachment structure of the
present invention that the collar part be formed as a single body
with the washer part.
According to the present invention, since the collar part is formed
as a single body with the washer part, it is possible to reduce
quantity of parts and time in assembling.
A load cell attachment structure of the present invention for
attaching a load cell to an attachment plate includes: a first
fastening part which is formed on a .[.load sensing part.].
.Iadd.main body .Iaddend.of the load cell; a second fastening part
which attaches the load cell to the attachment plate by engaging
with the first fastening part; a washer part which covers the load
sensing part, and is disposed between the load sensing part and the
attachment plate; and a collar part which is disposed between the
washer part and the second fastening part, wherein a length of the
collar part along an axis thereof is longer than a thickness of the
attachment plate.
According to the present invention, a clearance which absorbs the
wrap or incline of the attachment plate is appropriately formed
between the washer part and the second fastening part by the collar
part. In addition, the fastening force which is introduced through
the collar part is dispersed on the load sensing part evenly by the
washer part. Therefore, the load cell does not sense an undesired
load which is caused by the warp or incline of the attachment
plate, and dispersion of initial values of the load cell, which is
caused by difference in fastening torque is not caused. As a
result, it is possible to measure loads which act on the load
sensing part exactly.
It is preferable in the load cell attachment structure of the
present invention that the first fastening part be a male screw,
the second fastening part be a nut, and the collar part be disposed
between the washer part and the nut. Alternatively, it is
preferable in the load cell attachment structure of the present
invention, that the first fastening part be a female screw, the
second fastening part be a bolt, and the collar part be disposed
between the washer part and a top of the bolt.
It is preferable in the load cell attachment structure of the
present invention that the collar part be formed as a single body
with the washer part.
According to the present invention, since the collar part is formed
as a single body with the washer part, it is possible to reduce the
quantity of parts and time in assembling.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing the seat of a vehicle to which
a load cell attachment structure according to the present invention
is applied.
FIG. 2 is sectional view of the load cell attachment structure
according to the present invention.
FIG. 3 is sectional view of the load cell attachment structure
according to the present invention, in particular, showing a state
in which the attachment plate inclines.
FIG. 4 is sectional view of first variant of the load cell
attachment structure according to the present invention.
FIG. 5 is sectional view of second variant of the load cell
attachment structure according to the present invention.
FIG. 6 is sectional view of third variant of the load cell
attachment structure according to the present invention.
FIG. 7 is sectional view of a conventional load cell attachment
structure.
FIG. 8 is sectional view of another conventional load cell
attachment structure.
DETAILED DESCRIPTION OF THE INVENTION
A description is given below of a load cell attachment structure
according to one embodiment of the present invention with reference
to the drawings.
FIG. 1 shows the right half side of an occupant's seat 11 of a
vehicle. A seat frame .[.11.]. .Iadd.12 .Iaddend.which composes a
skeletal structure of the seat 11 is supported on a pair of seat
rails 14 so as to be capable of sliding in the lengthwise direction
of the vehicle. The seat rails 14 are spaced apart from each other
in the widthwise direction of the vehicle, and are fixed on a floor
panel 13 of the vehicle. Note that, only one of the pair of seat
rails 14 is shown in FIG. 1.
The seat rail 14 is composed of a rail main body 20 and a slider
21. The rail main body 20 extends along the lengthwise direction of
the vehicle, and is fixed on the floor panel 13. The slider 21
extends along the lengthwise direction of the vehicle, and is
supported on the rail main body 20 so as to be capable of sliding
in the lengthwise direction of the vehicle.
Load cells 25 which measure loads, are respectively mounted on a
front end part and a rear end part of the slider 21. Attachment
plates 26 spaced apart from each other in the widthwise direction
of the vehicle are fixed on a floor panel 13 of the vehicle.
The pair of attachment plates 26 is disposed under the seat frame
12. One of the pair of attachment plates 26 is disposed on the
right side of the seat 11, and is attached to the load cells 25
mounted on the slider 21, the other of the pair of attachment
plates 26 is disposed on the left side of the seat 11, and is
attached the load cells 25 mounted on that slider 21.
The load cell attachment structure of this embodiment includes a
male screw 36 (first fastening part) which is formed on a load
.[.sensing part 38.]. .Iadd.cell main body 35 .Iaddend.of the load
cell 25, a nut 50 (second fastening part) which attaches the load
cell 25 to the attachment plate 26 by engaging with the male screw
36, and a wave washer 47 (elastic body) which is disposed between
the attachment plate 26 and the nut 50.
As shown in FIG. 2, the load cell 25 has a base plate 31 which
extends in one direction. The base plate 31 is disposed along the
lengthwise direction of the vehicle the left-right direction in
FIG. 2. A front part and a rear part of the base plate 31 are
attached to the slider 21 with bolts 32.
As in the above description, the load cell 25 is attached to the
slider 21 through the base plate 31. A load cell main body 35 of
the load cell 25 is fixed on the center of an upper surface of the
base plate 31. The load cell main body 35 is formed as a
substantially column-like shape, the direction of load of the load
cell main body 35 being in the vertical direction. The male screw
36 is fixed on the center of an upper surface of the load cell main
body 35 so as to be protruding upward.
The load sensing part 38 is the upper surface of the load cell main
body 35 with the exception of the male screw 36. In other words,
the male screw 36 is formed on the load .[.sensing part 38.].
.Iadd.cell main body 35 .Iaddend.of the load cell 25. The load cell
main body 35 warps slightly when subjected to downward load from
the load sensing part 38, and measures load corresponding to the
amount of the warp.
A washer 40 is mounted on the load cell main body 35. The washer 40
is composed of a washer part 41 and a collar part 42. The washer
part 41 is formed as a disk shape, and has a circular hole at the
center thereof. The external diameter of the washer part 41 is the
same as the external diameter of the load sensing part 38. The
collar part 42 is formed as a cylinder shape, and the external
diameter of the collar part 42 is less than the external diameter
of the washer part 41. The collar part 42 is disposed on the washer
part 41 so as to protrude upward from the washer part 41, and is
formed as a single body with the washer part 41 so that an axis of
the washer part 41 and an axis of the collar part 42 coincide.
Since the axis of the washer part 41 and the axis of the collar
part 42 coincide, a penetration hole 43 is formed on the washer
part 40. The internal diameter of the penetration hole 43 is
greater than a external diameter of the male screw 36.
The male screw 36 is inserted into the penetration hole 43, and the
washer part 41 contacts the load sensing part 38, and thus the
washer 40 is mounted on the load cell main body 35. In this
condition, the whole of the load sensing part 38 is covered by the
washer part 41. Further, since a top end of the male screw 36 of
the load cell 25 protrudes upward from the washer 40, the upper
surface of the washer part 41, the upper end surface of the collar
part 42, and the upper surface of the load sensing part 38 are
parallel with each other. It is preferable that the external
diameter of the washer part 41 be the same as the external diameter
of the load sensing part 38, or be greater than the external
diameter of the load sensing part 38.
The male screw 36 is inserted into the collar part 42, and the
collar part 42 into which the male screw 36 is inserted is inserted
into an attachment hole 45 which is formed on the attachment plate
26, and thus the attachment plate 26 is mounted on the washer part
41. Note that the length of the collar part 42 in the vertical
direction is greater than the thickness of the attachment plate 26,
and accordingly a top end surface of the collar part 42 protrudes
upward from the attachment plate 26 contacting the washer part
41.
The wave washer 47 is mounted on the attachment plate 26, which
contacts the upper surface of the wave washer 47. The wave washer
47 is formed as a ring shape, and the external diameter of the wave
washer 47 is greater than the external diameter of the washer part
41. The collar part 42 protruding upward from the attachment hole
45 of the attachment plate 26 is inserted into a center hole of the
wave washer 47. When the wave washer 47 is not deformed, the
thickness of the wave washer 47 is greater than a difference
between the length of the collar part 42 in the vertical direction
and the thickness of the attachment plate 26, and when the wave
washer 47 is deformed, the thickness of the wave washer 47 is less
than the difference between the length of the collar part 42 in the
vertical direction and the thickness of the attachment plate 26.
Therefore, when the wave washer 47 is mounted on the attachment
plate 26 and is not deformed, a highest point of an upper surface
of the wave washer 47 is positioned above the upper end surface of
the collar part 42.
The washer 49 is mounted on the wave washer 47. The male screw 36
protruding upward from the penetration hole 43 of the washer 40 is
inserted into a center hole of the washer 49. The internal diameter
of the washer 49 is greater than the external diameter of the male
screw 36, and is less than the external diameter of the collar part
42. The external diameter of the washer 49 is approximately the
same as the external diameter of the wave washer 47.
The nut 50 is thread-engaged with the male screw 36. The nut is
fastened at predetermined torque. Therefore, the washer 49 and the
washer 40 are sandwiched to be fixed between the nut 50 and the
load cell 25. That is, a lower surface of the nut 50 closely
contacts an upper surface of the washer 49. Further, a lower
surface of the washer 49 closely contacts the collar part 42 of the
washer 40, and a lower surface of the washer part 41 of the washer
40 closely contacts an upper surface of the load sensing part 38 of
the load cell main body 35. In this condition, since the washer 49
and the washer 40 are close to each other, the wave washer 47 which
is sandwiched between the washer 40 and washer 49 deforms
elastically. When the wave washer 47 deforms elastically, the
attachment plate 26 is pushed against the washer part 41 which is
positioned under the attachment plate 26 due to the elastic force
of the wave washer 47.
The load cell 25 is attached to the attachment plate 26 by the nut
50 being thread-engaged with the male screw 36. Further, the whole
of the load sensing part 38 is covered by the washer part 41, and
the washer part 41 is sandwiched between the load sensing part 38
and the attachment plate 26. Furthermore, the collar part 42 which
is thicker than the thickness of the attachment plate 26 is
disposed between the washer part 41 and the nut 50. Moreover, the
wave washer 47 is disposed between the attachment plate 26 and the
nut 50.
As in the above description, four corners of the seat 11, that is
the front part and the rear part of the pair of the seat frames 12
are supported by the seat rails 14 which are spaced apart from each
other in the widthwise direction by way of the four load cells 25.
Load which is added onto the seat 11 is introduced from the seat
frame 12 into the load sensing part 38 through the washer part 41.
The load cell main body 35 warps slightly due to being introduced
load from the load sensing part 38, and generates an electrical
charge corresponding to the load which is introduced through the
washer part 41. The electrical charge is measured by a control
section (not shown in the figures).
Based upon the load which is measured by the four load cells 25,
the control section makes a decision as to whether or not a
occupant is seated on the seat 11. Also, the control section makes
a decision as to whether the occupant is an adult or a child.
Further, based upon the decision, the control section controls the
way of operating and the like of the air bag system, when a
collision of the vehicle happens.
According to the load cell attachment structure of above described
embodiment, since the wave washer 47 is disposed between the
attachment plate 26 and nut 50, as shown in FIG. 3, if the
attachment plate 26 warps or inclines, such warp or incline is
absorbed by the deformation of the wave washer 47. Therefore, the
load cell 25 does not sense an undesired load (in other words,
"offset load") caused by the warp or incline of the attachment
plate 26 or imperfect assembly. Further, the weight of the seat 11
and of the occupant on the seat 11 is introduced from the
attachment plate 26 to the load sensing part 38 through the washer
40. As a result, it is possible to measure load which acts on the
load sensing part 38 exactly.
As shown in FIG. 3, the load cell attachment structure of this
embodiment includes the washer 40 which is composed of the washer
part 41 and the collar part 42. The washer part 41 substantially
covers the load sensing part 38, and is sandwiched between the load
sensing part 38 and the attachment plate 26. The collar part 42 is
disposed between the washer part 41 and the nut 50, the length of
the collar part 42 in the axial direction being greater than the
thickness of the attachment plate 26. In other words, the length of
the collar part 42 in the axial direction is greater than the sum
of the thickness of the attachment plate 26 and the minimum
thickness of the wave washer 47.
Due to this, a clearance which absorbs the wrap or incline of the
attachment plate 26 is appropriately formed between the nut 50 and
the washer part 41 by the collar part 42. In addition, the
fastening force which is introduced through the collar part 42 is
dispersed on the load sensing part 38 evenly by the washer part 41.
Therefore, the load cell .[.26.]. .Iadd.25 .Iaddend.does not sense
an undesired load which is caused by the warp or incline of the
attachment plate 26 due to a minor collision of the vehicle or the
fastening force. As a result, it is possible to measure loads
exactly.
In addition, the fastening force which is introduced through the
collar part 42 is dispersed on the load sensing part evenly by the
washer part 41. Therefore, the load cell 25 does not sense an
undesired load (in other words, "drift force along the axis") which
is caused by the fastening force, and dispersion of initial values
of the load cell caused by difference in fastening torque can be
reduced. As a result, it is possible to measure load exactly. That
is, when the washer 40 is a collar only, in the total sensing range
of the load sensor 25, the range defined by counting out the weight
of the seat as well as drift from the fastening force becomes the
range that can be used to sense the weight of the occupant.
However, when the washer 40 is provided with the washer portion 41
and the collar portion 42, in the total sensing range of the load
sensor 25, the range defined by counting out only the weight of the
seat becomes the range that can be used to sense the weight of the
occupant. Accordingly, the effective sensing range of the sensor
becomes extremely wide.
Since the wave washer 47 is disposed between the attachment plate
26 and the nut 50, if the attachment plate 26 does not warp or
incline, or if the attachment plate 26 warps, the wave washer 47
deforms corresponding to the warp or incline. Therefore, it is
possible to reduce the backlash of the attachment plate 26 which is
disposed between the washer 49 and the washer part 41.
Since the collar part 42 is formed as a single body with the washer
part 41, it is possible to reduce the quantity of parts and time in
assembly. Naturally, the collar part 42 and the washer part 41 can
also be separate. .[.Note that, if the load cell 25 can measure
loads exactly without the dispersion of the fastening force over
the load sensing part 38, as shown in FIG. 4, the washer 40 may
include only the collar part 42 without the washer part 41..].
The load cell attachment structure of this embodiment may include
another elastic body instead of the wave washer 47. For example, as
shown in FIG. 5, a plate-spring shape washer 52 may be disposed
between the nut 50 and the washer 41. The washer 52 is composed of
a flat plate part 53 with a ring shape and a tapered part 54 which
is disposed on the outside edge of the flat plate part 53. The
tapered part 54 inclines with respect to the flat plate part 53.
The flat plate part 53 closely contacts the lower surface of the
nut 50 and the upper end surface of the collar part 42, and an
outside edge of the tapered part 54 closely contacts the attachment
plate 26.
Further, as shown in FIG. 6, a plate-spring 62 which is sandwiched
between washers 63, 64 may be disposed between the nut 50 and the
washer 40. The plate-spring 62 is composed of a flat plate part 60
with a ring shape and a tapered part 61 which is disposed on the
outside edge of the flat plate part 60. The tapered part 61
inclines with respect to the flat plate part 60. The washer 63 is
disposed between the plate-spring 62 and the nut 50, and the washer
64 is disposed between the plate-spring 62 and the collar part 42.
The external diameter of the washer 63 is less than the external
diameter of the washer 64, and the external diameter of the
plate-spring 62 is less than the external diameter of the washer
64. The washer 63 closely contacts the lower surface of the nut 50,
and the washer 64 closely contacts the upper end surface of the
collar part 42. Further, an outside edge of the taper plate part 61
closely contacts the attachment plate 26. A resinous cover 66 is
disposed on an inside edge of the attachment hole 45 of the
attachment plate 26. The cover 66 prevents the inside edge of the
attachment hole 45 from contacting the washer 40.
In the above embodiment, the structure in which the load cell 25 is
attached to the attachment plate 26 by the male screw 36 being
disposed on the load sensing part 38 of the load cell 25, and the
nut 50 being thread-engaged with the male screw 36, is explained.
However, a structure in which the load cell 25 is attached to the
attachment plate 26 by a female screw being disposed on the load
sensing part 38 of the load cell 25, and a bolt being
thread-engaged with the female screw, may be applied. In this
structure, the bolt is inserted into the penetration hole 43, and
the collar part 42 of the washer 40 is disposed between the washer
part 41 and a top of the bolt. Also, the wave washer 47 is disposed
between the attachment plate 26 and the top of the bolt.
While preferred embodiments of the invention have been described
and illustrated above, it should be understood that these are
exemplary of the invention and are not to be considered as
limiting. Additions, omissions, substitutions, and other
modifications can be made without departing from the spirit or
scope of the present invention. Accordingly, the invention is not
to be considered as being limited by the foregoing description, and
is only limited by the scope of the appended claims.
* * * * *