BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
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The present invention relates to a temperature-responsively
operated drive mechanism for use in a freeze-indicating
sign system for warning a passer, a driver or a
road manager of the freezing of a road surface occurring in
winter season.
DESCRIPTION OF THE RELATED ART
-
A large number of such freeze-indicating sign
systems have been proposed as disclosed in Japanese Utility
Model Application Laid-open Nos.52-142392, 58-10913 and 62-12612,
Japanese Patent Application Laid-open No.54-19760
and the like.
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The present applicant has proposed a freeze-indicating
sign system, for example, in Japanese Patent
No.2889545 and the like, in which problems associated with
the above conventional systems have been overcome. This
freeze-indicating sign system includes a switching-type
indicating means adapted to be turned to indicate "caution
to freeze" and "caution to travel" in a switching manner.
The switching-type indicating means can be turned based on
a substantially freezing temperature by a temperature-responsively
operated drive means formed using a shape
memory alloy for applying a switching drive force to the
switching-type indicating means, so that the indications in
a housing provided in the switching-type indicating means
can be switched over from one to another at the
substantially freezing temperature. It is possible to
inform a driver or a road manager or the like of the
freezing of a road surface occurring in winter season
without recourse to an external power source. Further, the
size of the freeze-indicating sign system can be increased
two-dimensionally without an increase in amount of
temperature-responsively operated drive means displaced and
an increase in driving energy.
SUMMARY OF THE INVENTION
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It is an object of the present invention to provide a
temperature-responsively operated drive mechanism which is
designed, so that the speed of switching turning movement
of a switching-type indicating means in such a freeze-indicating
sign system can be increased, whereby the
switching of the indications at a predetermined temperature
corresponding to the freezing temperature can be conducted
quickly and automatically to promptly inform a driver or a
road manager or the like of the freezing of a road
occurring in winter season, thereby ensuring the safety of
a road traffic.
-
To achieve the above object, according to the present
invention, there is provided a temperature-responsively
operated drive mechanism designed to provide a switching
drive force to switching-type indicating means placed on a
freeze-indicating sign system, comprising a member made of
a shape memory alloy for providing the switching drive
force to the switching-type indicating means in accordance
with a temperature such as a predetermined temperature, and
a drive force assisting means for providing an assist force
for assisting in the switching drive force during switching
operation of the member made of the shape memory alloy.
-
With the above arrangement, when the temperature of
the outside air reaches a predetermined temperature at
which the switching operation is required, the drive force
assisting means provides the assist force for assisting in
the switching drive force to the member of the shape memory
alloy for providing the switching drive force to the
switching-type indicating means. Therefore, the switching
of the indications on the switching-type indicating means
at the predetermined temperature corresponding to the
freezing temperature can be conducted quickly and
automatically. Thus, it is possible to quickly inform a
driver or a road manager or the like of the freezing of a
road occurring in winter season to ensure the safety of
road traffic.
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The drive force assisting means may be comprised of
a permanent magnet and a ferromagnetic member disposed
between a movable member in the switching-type indicating
means and a stationary member of the freeze-indicating sign
system for providing a magnetic force.
-
With the above arrangement, when the switching
operation of the switching-type indicating means is started
by the member made of the shape memory alloy, a magnetic
force is provided between the permanent magnet and the
ferromagnetic member to provide the assist force for
assisting in the switching drive force provided by the
member made of the shape memory alloy, whereby the
switching of the indications on the switching-type
indicating means can be conducted quickly and
automatically.
-
The above and other objects, features and advantages
of the invention will become apparent from the following
description of the preferred embodiment taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
-
- Fig.1 is a perspective view of a freeze-indicating
sign system which has a temperature-responsively operated
drive mechanism according to an embodiment the present
invention placed thereon and which is in a recurrent
reflection operational state;
- Fig.2 is a perspective view of the freeze-indicating
sign system which has the temperature-responsively operated
drive mechanism according to the embodiment the present
invention placed thereon and which is in a mounted state;
- Fig.3 is a perspective view of the freeze-indicating
sign system which has the temperature-responsively operated
drive mechanism according to the embodiment the present
invention placed thereon and which is in a service state;
- Fig.4 is a front view of the freeze-indicating sign
system which has the temperature-responsively operated
drive mechanism according to the embodiment the present
invention placed thereon and which is in another service
state;
- Fig.5 is a back view of a housing of the freeze-indicating
sign system having the temperature-responsively
operated drive mechanism according to the embodiment the
present invention placed thereon;
- Fig.6 is a sectional view of the housing of the
freeze-indicating sign system having the temperature-responsively
operated drive mechanism according to the
embodiment the present invention placed thereon, taken
along a line A-A in Fig.5;
- Fig.7 is a developed schematic view of parts of the
freeze-indicating sign system having the temperature-responsively
operated drive mechanism according to the
embodiment the present invention placed thereon;
- Fig.8 is an enlarged developed view showing
essential portions of switching-type indicating means
mounted on the freeze-indicating sign system having the
temperature-responsively operated drive mechanism according
to the embodiment the present invention placed;
- Figs.9a and 9b are diagrams for explaining the
turning movement of the switching-type indicating means of
the freeze-indicating sign system having the temperature-responsively
operated drive mechanism according to the
embodiment the present invention placed thereon;
- Fig.10a is a sectional view of an upper attaching
member mounted on the freeze-indicating sign system having
the temperature-responsively operated drive mechanism
according to the embodiment the present invention placed
thereon, and Fig.10b is a sectional view of the lower
attaching member mounted on the freeze-indicating sign
system;
- Fig.11a is a plan view of the lower attaching member
when the switching-type indicating means of the freeze-indicating
sign system have been turned in a clockwise
direction, Fig.11b is a plan view of the lower attaching
member when the switching-type indicating means have been
turned in a counterclockwise direction, and Fig.11c is a
front view of only the lower attaching member;
- Fig.12 is a sectional view of a movable member and
the lower attaching member mounted on the freeze-indicating
sign system;
- Fig.13a is a view showing the relation between the
movable member and pinions in the freeze-indicating sign
system in a state in which the movable member has been
moved rightwards, and Fig.13b is a view in a state the
movable member has been moved leftwards;
- Fig.14 is a plan view of the switching-type
indicating means turned in the clockwise direction by the
temperature-responsively operated drive mechanism according
to the embodiment of the present invention;
- Fig.15 is a plan view of the switching-type
indicating means turned in the counterclockwise direction
by the temperature-responsively operated drive mechanism
according to the embodiment of the present invention.
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DESCRIPTION OF THE PREFERRED EMBODIMENT
-
The present invention will now be described by way of
an embodiment of the present invention with reference to
the accompanying drawings. The same reference characters
in Figures designate the same or corresponding components
or portions in the embodiments. Particularly, components
or portions designated by reference character with suffixes
A, B, C and D attached thereto to indicate the use of parts
of the same construction are basically common with
component or portions designated by reference characters
with not suffix attached thereto.
-
First, a freeze-indicating sign system provided with
a temperature-responsively operated drive mechanism
according to the present invention will be described.
-
Referring to Figs.1 to 4, a freeze-indicating sign
system is attached to a white support post 2 by a known
attaching means 3, and has a side strip-indicating function
for clearly indicating the presence of a side strip, for
example, by a white or yellow recurrent reflection surface
and a freeze-indicating function. The attaching means 3 in
the present embodiment includes a grooved rail member 5
mounted to a housing 4 formed as a template made of
aluminum, commercially available bolts whose heads are
inserted into the rail member 5 to inhibit the turning
movement, a saddle 6 fitted at its opposite ends over the
inserted bolt, and nuts 7 threadedly engaged with the
bolts, thereby clamping the support post 2 between the rail
member 5 and the saddle 6. Of course, the attaching means
3 used to carry out the present invention may be integrally
mounted directly to the support post 2 by bolts and nuts.
The housing 4 may be formed into a box shape from an opaque
synthetic resin material or a metal plate, a template or
the like. In the present embodiment, the housing 4 is
formed as a template of aluminum. A transparent plate 4a
comprising a transparent acrylic plate or a transparent
glass plate is disposed on a front surface of the housing
4. The transparent plate 4a is disposed on the front
surface, but may be a plate provided with windows
functioning at least as a side strip sign and a freeze
sign, or a plate formed of a transparent material in
correspondence to front half of the housing 4. Of course,
the transparent plate 4a may be a plate formed of a
transparent material in correspondence to the entire
housing 4.
-
As shown in Figs.1, 2, 5 and 6, the housing 4 in the
present embodiment is the transparent plate 4a and a back
lid 9 attached to a back of a case body 8 which will be
described hereinafter. Side strip sign faces 11A, 11B, 11C
and 11D (common "side strip sign faces" will be denoted
simply by "11" hereinafter) and freeze sign faces 12A, 12B,
12C and 12D (common "freeze sign faces" will be denoted
simply by "12" hereinafter) provided on switching- type
indicating means 10A, 10B, 10C and 10D (common "switching-type
indicating means" will be denoted simply by "11"
hereinafter) are faces visually observed from the
transparent plate 4a. In the present embodiment, the
switching-type indicating means 10 are formed so that the
indication can be switched over by turning the switching-type
indicating means 10 about a vertical axis. It is of
course that a sealant or a sealing material or an adhesive
(not shown) is filled or interposed between the case body 8
and the transparent plate 4a and between the case body 8
and the back lid 9 to ensure a required sealability.
Reference character 4b shown in Fig.5 is a screw bore for
securing the back lid 9 to the housing 4, and reference
characters 9a and 9b relatively show positions of the screw
bores in the back lid 9.
-
Figs.3 and 4 show a freeze-indicating sign system
according the embodiment of the present invention in a
certain service state. A freeze-indicating sign device 1
(1U) located at an upper portion of the freeze-indicating
sign system is adapted to indicate "tra" when the
temperature is raised to exceed a first preset value, and
to indicate "free" when the temperature is dropped to a
level lower than a second preset value lower than the first
preset value, and a freeze-indicating device 1 (1D) located
at a lower portion of the freeze-indicating sign system is
adapted to indicate "vel" when the temperature is raised to
exceed a first preset value, and to indicate "ze" when the
temperature is dropped to the level lower than the second
preset value lower than the first preset value. An
indicating plate 100 located at a lower portion of the
freeze-indicating device 1 (1D) indicates letters of
caution, and adapted to indicate "caution to freeze" by
black letters on a red substrate when temperature is raised
to exceed the first preset value, as in Fig.4a which is a
front view showing one mode of the service state, and to
indicate "caution to travel" by black or blue letters on a
yellow substrate when the temperature is equal to or higher
than a predetermined value as in Fig.4b. Of course,
"caution to travel" and "caution to freeze" may be
indicated by black letters on the same yellow substrate or
the like.
-
In the present embodiment, the freeze-indicating
sign system 1 may indicate a side strip sign and a freeze
sign by colors such as yellow and red, white and red, or
blue and red without provision of letters. In the
embodiment shown in Fig.4, the freeze-indicating sign
system 1 is divided into a freeze-indicating sign device 1U
and a freeze-indicating sign device 1D. In the carrying-out
of the embodiment, the freeze-indicating device 1 is
vertically elongated or laterally elongated and capable of
indicating one letter or a plurality of letters, e.g.,
"travel" or "freeze", or "caution to travel" or "caution to
freeze" in the same housing 4. Particularly, when letters
are written on a surface having a side strip sign and a
freeze sign formed thereon, the recurrent reflection face
can represent a side strip sign function and a freeze sign
function by only letters indicated by one color selected
from, for example, white, yellow, red and blue colors and
by another complementary color.
-
In the freeze-indicating sign system 1 according to
the embodiment of the present invention, the indication of
freeze having no letter, the indication of freeze provided
with letters and the indication of freeze provided with
characters are not varied in concept from one another and
hence, the following description is on the assumption that
the concepts are common.
-
Referring to Fig.7, an upper attaching member 60
disposed at an upper portion of the housing 4 is secured to
the back lid 9 by screws 60a in such a manner that the
screws 60a threadedly engaged in a plurality of screw bores
60b are threadedly inserted into screw bores 9a in the back
lid 9. A lower attaching member 20 disposed at a lower
portion of the housing 4 is secured to the back lid 9 by
screws 20a in such a manner that the screws 20a threadedly
engaged in a plurality of screw bores 20b are threadedly
inserted into screw bores 9b in the back lid 9.
-
In the present embodiment, four switching-type
indicating means 10A, 10B, 10C and 10D are rotatably
supported between the upper attaching member 60 and the
lower attaching member 20.
-
The structures of the upper and lower attaching
member 60 and 20 and the switching-type indicating means 10
will be described below with reference to Figs.8 and 9
(lower portions of these figures correspond to the front
side of the housing, and the same is true in Figs.11 and
13).
-
The switching-type indicating means 10 has an upper
end member 13 formed at an upper portion thereof and a
lower end member 14 formed at a lower portion thereof, and
is rotatable about an upper end shaft 13a of the upper end
member 13 and a lower end shaft 14a of the lower end member
14. In the switching-type indicating means 10 in the
present embodiment, a V-shaped plate member 15 folded into
a V-shape is bonded between the upper and lower end members
13 and 14, and a synthetic resin sheet containing a
recurrent reflection material incorporated therein is
adhered to an outer surface of the V-shaped plate member
15. One of faces of the V-shaped plate member 15 is a side
strip sign face 11A, 11B, 11C, 11D, and the other face is a
freeze sign face 12A, 12 B, 12C, 12D for indicating a
frozen state of a road surface.
-
When the temperature of the outside air is raised to
exceed a value higher than the first preset value, the
switching-type indicating means 10A, 10B, 10C and 10D
disposed within the housing 4 are turned clockwise through
approximately 120 degree from the state shown in Fig.9b,
and as a result, the side strip sign faces 11A, 11B, 11C
and 11D are on the side of the transparent plate 4a of the
housing 4, as shown in Fig.9a. When the temperature of the
outside air is dropped down to a value lower than the
second preset value, the switching-type indicating means
10A, 10B, 10C and 10D disposed within the housing 4 are
turned counterclockwise through approximately 120 degree
from the state shown in Fig.9a, and as a result, the freeze
sign faces 12A, 12B, 12C and 12D are on the side of the
transparent plate 4a of the housing 4, as shown in Fig.9b.
Namely, when the side strip sign faces 11A, 11B, 11C and
11D of the switching-type indicating means 10A, 10B, 10C
and 10D are flush with one another, as shown in Fig.9a,
light is reflected from the entire side strip sign faces
11A, 11B, 11C and 11D in a direction of incidence, thereby
clearly indicating that a road surface is not in a frozen
state. When the switching-type indicating means 10A, 10B,
10C and 10D are turned through approximately 120 degree
from the states shown in Fig.9a and as a result, different
faces are substantially on a plane, the freeze sign faces
12A, 12B, 12C and 12D are flush with one another, whereby
light is reflected from the entire freeze sign faces 12A,
12B, 12C and 12D in the direction of incidence, thereby
clearly indicating that the road surface is in a frozen
state or in a freezable state.
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The number of the switching-type indicating means
10A, 10B, 10C and 10D in the present embodiment is four,
but is not limited to four. However, if the number of the
switching-type indicating means 10A, 10B, 10C and 10D is in
a range of 2 to 5 as in the present embodiment, each of the
switching-type indicating means can be formed so that the
contact resistance thereof is relatively small, and the
mechanical strength thereof is also strong.
-
The upper end of the switching-type indicating means
10 in the present embodiment is mounted to the upper
attaching member 60, as shown in Fig.10a.
-
The upper attaching member 60 is provided with
through-bores 61 for mounting of the four switching-type
indicating means 10A, 10B, 10C and 10D. The upper end
shafts 13a of the upper end members 13 formed at the upper
portion of the switching-type indicating means 10 are
inserted into the through-bores 61 with a metal bearing 62
interposed between the through-bore 61 and the upper end
shaft 13a. A portion of the upper end shaft 13a located in
the metal bearing 62 is threadedly fixed by a bolt 65 with
a slide ring 63 (constituting a slide bearing having a
lower contact resistance surface, e.g., a thrust sphere
bearing, a dry bearing and the like) interposed
therebetween along with a washer 64 and the metal bearing
62. Namely, the upper end shaft 13a is clamped firmly by
the bolt 65 with the washer 64 and the slide ring 63
interposed therebetween. Therefore, the switching-type
indicating means 10 is turned in unison with the slide ring
63, and a flange portion on an upper surface of the metal
bearing 62 and the slide ring 63 are turned in states of a
low frictional resistance.
-
The lower end of the switching-type indicating means
10 is mounted to the lower attaching member 20, as shown in
Fig.10b.
-
The lower attaching member 20 has columnar
projections 21A, 21B, 21C and 21D formed thereon for
mounting of the four switching-type indicating means 10A,
10B, 10C and 10D (common "projections" will be denoted
simply by "21" hereinafter). A sleeve 23 is embedded in
each of the projections 21A, 21B, 21C and 21D. The sleeve
23 has a low frictional resistance and functions as a
bearing, and is embedded in a lower end of the lower end
shaft 14a of the lower end member 14 of the switching-type
indicating means 10. Pinions 14b (14bA, 14bB, 14bC and
14bD) are formed on outer sides of the lower ends of the
lower end shafts 14a of the lower end members 14. The
sleeve 23 is located inside the pinion 14b and fixed to the
projection 21, so that the lower end shaft 14a of the lower
end member 14 is inhibited from being horizontally moved by
embedding the sleeve 23 into the lower end shaft 14a, but
can be turned in a circumferential direction of the sleeve
23. In this case, a small distance is provided between the
lower end of the lower end shaft 41a of the lower end
member 14 and the upper surface of the lower attaching
member 20, so that both of them are not brought into
contact with each other. Namely, the switching-type
indicating means is supported in a cantilever manner only
on the side of the upper attaching member 60.
-
As shown in Figs.8 and 11, the lower attaching
member 20 is provided on its upper surface with a clockwise
turning-movement stopper 22R (22RA, 22RB, 22RC and 22RD)
for restraining the clockwise turning movement of the
switching-type indicating means 10, and a counterclockwise
turning-movement stopper 22L (22LA, 22LB, 22LC and 22LD)
for restraining the counterclockwise turning movement of
the switching-type indicating means 10. An abutment
projection 14c (14cA, 14cB, 14cC and 14cD) protruding
downwards from the lower end member 14 restrains the
leftward turning movement together with the
counterclockwise turning-movement stopper 22L (22LA, 22LB,
22LC and 22LD) and at this time, the freeze sign faces 12A,
12B, 12C and 12D are flush with one another on the side of
the transparent plate 4a of the housing 4, as shown in
Fig.9b and 11a. An abutment projection 14d (14dA, 14dB,
14dC and 14dD) protruding downwards from the lower end
member 14 restrains the rightward turning movement together
with the clockwise turning-movement stopper 22R (22RA,
22RB, 22RC and 22RD) and at this time, the side strip sign
faces 11A, 11B, 11C and 11D are flush with one another on
the side of the transparent plate 4a of the housing 4, as
shown in Fig.9a and 11b.
-
The positions of the V-shaped plate member 15 of the
switching-type indicating means 10 and the side strip sign
face and the freeze sign face 12 bonded to the V-shaped
plate member 15 are determined depending on the distance
between the upper and lower attaching members 60 and 20,
and the turning movement of the switching-type indicating
means 10 causes the flange portion on the upper surface of
the metal bearing 62 and the slide ring 63 to be turned in
the low frictional resistance state, thereby determining a
torque required for turning the switching-type indicating
means 10. However, the weights of the V-shaped plate
member 15 and the side strip sign face 11 and the freeze
sign face 12 between the upper and lower attaching members
60 and 20 exert little influence to the torque and hence,
the lengths of the V-shaped plate member 15 and the side
strip sign face 11 and the freeze sign face 12 between the
upper and lower attaching members 60 and 20 of the
switching-type indicating means 10 can be increased.
-
A temperature-responsively operated drive mechanism
29 according to the present invention will be described
below with reference to Figs.11 to 13.
-
The temperature-responsively operated drive
mechanism 29 according to the present invention is
comprised of a movable member 40, compressed springs 35 and
36 made of a shape memory alloy, a driving-force assisting
means 50 and the like.
-
The movable member 40 is mounted to the lower
attaching member 20, as shown in Fig.12. Two guide
projections 24 are formed on the upper surface of the lower
attaching member 20, and a slide washer 25 having a small
contact resistance of its upper surface is fitted over each
of the projections 24. A bush 26 having a small contact
resistance is fitted over an outer periphery of each of the
guide projections 24, and a guide bore 42a and a guide bore
42c each comprising an elongated bore in the movable member
40 are fitted over the bush 26, thereby facilitating the
straight movement of the movable member 40. To prevent the
bush 26 from being separated off each of the guide
projections 24, the bush 26 is threadedly fixed to each of
the guide projections 24 by a mounting screw 27, so that
the separation-off of the bush 26 and the movement of the
bush 26 in a direction parallel to a direction of
protrusion of the guide projection 24 are restrained.
-
As shown in Figs.8, 12 and 13, racks 41A, 41B, 41C
and 41D are formed on lengthwise one side of the movable
member 40, i.e., on longer sides of movable bores 41A, 42B,
42C and 42D of an oblong shape slightly larger than the
guide bores 42a and 42c, so that they are meshed with the
pinions 14b (14bA, 14bB, 14bC and 14bD) each formed at the
lower end of the lower end shaft 14a of the lower end
member 14. Therefore, the racks 41A, 41B, 41C and 41D are
moved laterally by the lengthwise leftward and rightward
straight movements of the movable member 40, whereby the
pinions 14bA, 14bB, 14bC and 14bD meshed with the racks
41A, 41B, 41C and 41D are turned to turn the switching-type
indicating means 10A, 10B, 10C and 10D. In this case, when
the racks 41A, 41B, 41C and 41D are moved leftwards as
viewed in Fig.13, the switching-type indicating means 10A,
10B, 10C and 10D are turned counterclockwise. When the
racks 41A, 41B, 41C and 41D are moved rightwards as viewed
in Fig.13, the switching-type indicating means 10A, 10B,
10C and 10D are turned clockwise.
-
Hook portions 43, 44, 45 and 46 are formed on both
of front and rear sides of the movable member 40
perpendicularly to the lengthwise direction of the movable
member 40, and compressed springs 35 and 36 each made of a
shape memory alloy are disposed between the hook portions
43 and 44 and pins 35a and 36a disposed on the upper
surface of the lower attaching member 20, so that the
distance between the hook portions 43 and 44 and the pins
35a and 36a can be reduced. In addition, compressed
springs 30 and 31 having such a characteristic that they
are expanded and contracted to an extremely small extent
depending on the temperature (linearly expanded to an
extremely small extent) are disposed between the hook
portions 45 and 46 and pins 30a and 31a disposed on the
upper surface of the lower attaching member 20, so that the
distance between the hook portions 45 and 46 and the pins
30a and 31a can be reduced. Further, the compression force
of the compressed springs 35 and 36 exerts an influence
larger than the resilient force of the compressed springs
30 and 31. In usual, a second preset lower temperature
determined supposing that the temperature of the compressed
springs 35 and 36 made of the shape memory alloy has been
dropped, is set at a value substantially near the freezing
point of the compressed springs 35 and 36, i.e., in a range
of 0 to 3° but slightly varied in different localities. A
first preset temperature determined supposing the
temperature of the compressed springs 35 and 36 has been
raised, depends on the second preset temperature of the
compressed springs 35 and 36, and is set by the temperature
raised in a range of 2 to 5° determined by a hysteresis.
More specifically, the resilient force of the compressed
springs 35 and 36 made of the shape memory alloy is
memorized, so that for example, when the temperature of the
outside air has been dropped to 1 to 2°C or less lower than
the second preset temperature, each of turns of the spring
is deformed to reduce the compressed density, and when the
temperature of the outside air has been raised to 4 to 5°C
or more to exceed the second preset temperature and the
first preset temperature, each of the turns is deformed to
increase the compressed density.
-
When the temperature of the outside air has been
dropped from a higher level down to the second preset
temperature and in the present embodiment to 1 to 2°C in
the state shown in Fig.13b, the compressed springs 35 and
36 made of the shape memory alloy are deformed to reduce
the compressed density of each of their turns, thereby
biasing the movable member 40 leftwards together with the
resilient force of the compressed springs 30 and 31. Thus,
the switching-type indicating means 10A, 10B, 10C and 10D
are turned counterclockwise and finally, the freeze sign
faces 12A, 12B, 12C and 12D are flush with one another on
the side of the transparent plate 4a of the housing 4, as
shown in Fig.13a.
-
When the temperature of the outside air has been
raised from a lower level up to a temperature exceeding the
first preset temperature, e.g., 1 to 2°C of the second
preset temperature and the hysteresis in the state shown in
Fig.13, the resilient force of the compressed springs 35
and 36 made of the shape memory alloy, because it increases
the compressed density of each of the turns of the springs,
is larger than that of the compressed springs 30 and 31 for
biasing the movable member 40 in the lateral direction in
the present embodiment, thereby biasing the movable member
40 rightwards. Thus, the switching-type indicating means
10A, 10B, 10C and 10D are turned clockwise and finally, the
side strip sign faces 11A, 11B, 11C and 11D are flush with
one another on the side of the transparent plate 4a of the
housing 4, as shown in Fig.13a.
-
Therefore, when the temperature of the compressed
springs 35 and 36 made of the shape memory alloy is
substantially equal to or lower than the freezing point,
the resilient force of the compressed springs 35 and 36 for
moving the movable member 40 is weaker than that of the
compressed springs 30 and 31 for biasing the movable member
40 in the opposite direction. However, when the
temperature of the compressed springs 35 and 36 exceeds the
first preset temperature higher than the freezing point,
the resilient force of the compressed springs 35 and 36 for
moving the movable member 40 is stronger than that of the
compressed springs 30 and 31 for biasing the movable member
40 in the opposite direction. Therefore, when the
temperature of the compressed springs 35 and 36 is equal to
or lower than the freezing point, the switching-type
indicating means 10A, 10B, 10C and 10D are turned
counterclockwise, until such turning movement is limited,
whereby the freeze sign faces 12A, 12B, 12C and 12D are
flush with one another on the side of the transparent plate
4a of the housing 4. When the temperature of the
compressed springs 35 and 36 is not equal to or lower than
the freezing point, the switching-type indicating means
10A, 10B, 10C and 10D are turned clockwise, until such
turning movement is limited, whereby the side strip sign
faces 11A, 11B, 11C and 11D are flush with one another on
the side of the transparent plate 4a of the housing 4.
-
As shown in Figs.8 and 11, the driving-force
assisting means 50 in the present embodiment is comprised
of the counterclockwise turning-movement stoppers 22L
(22LA, 22LB, 22LC and 22LD) and the clockwise turning-movement
stoppers 22R (22RA, 22RB, 22RC and 22RD) fixedly
placed on the upper surface of the lower attaching member
20 for restraining the counterclockwise and clockwise
turning-movement of the switching-type indicating means 10,
respectively, and the abutment projections 14c (14cA, 14cB,
14cC and 14cD) and the abutment projections 14d (14dA,
14dB, 14dC and 14dD) protruding downwards from the lower
end members 14 of the switching-type indicating means 10
for restraining the counterclockwise and clockwise turning
movement of the switching-type indicating means 10,
respectively. In the present embodiment, each of the
counterclockwise turning-movement stoppers 22L (22LA, 22LB,
22LC and 22LD) and the clockwise turning-movement stoppers
22R (22RA, 22RB, 22RC and 22RD) is a permanent magnet, on
the one hand, and each of the abutment projections 14c
(14cA, 14cB, 14cC and 14cD) and the abutment projections
14d (14dA, 14dB, 14dC and 14dD) is made of a ferromagnetic
member such as iron. A magnetic force applied between the
permanent magnet (the counterclockwise turning-movement
stopper 22L and the clockwise turning-movement stoppers
22R) and the ferromagnetic member (the abutment projection
14c and the abutment projection 14d) acts as an assist
force for assisting in the switching drive force provided
by the compressed springs 35 and 36 made of the shape
memory alloy for applying the counterclockwise and
clockwise switching drive force to the switching-type
indicating means 10.
-
The freeze-indicating sign system 1 and the
temperature-responsively operated drive mechanism 29
constructed in the above manner according to the present
embodiment are operated as described below.
-
The temperature of the outside air is brought into a
temperature capable of operating the compressed springs 35
and 36 made of the shape memory alloy by the heat transfer,
heat emission or the like of the housing 4. For example,
when the temperature of the outside air becomes the first
preset temperature in a range of 4 to 5°C exceeding the
substantially freezing temperature, the compressed springs
35 and 36 made of the shape memory alloy is deformed and
compressed strongly more than the resilient force of the
other compressed springs 30 and 31, whereby the movable
member 40 is moved rightwards as viewed in Fig.13 by the
resilient force of the compressed springs 35 and 36. Thus,
the switching-type indicating means 10 are turned clockwise
through approximately 120 degree from the state shown in
Fig.9b to the state shown in Fig.9a, whereby the side strip
sign faces 11 are turned to the side of the transparent
plate 4a of the housing 4. When the clockwise turning
movement of the switching-type indicating means 10 is
started, the ferromagnetic members (the abutment
projections 14d) of the temperature-responsively operated
drive mechanism 29 are moved gradually toward the permanent
magnets (the counterclockwise and clockwise turning- movement
stoppers 22L and 22R), and a magnetic force
between both of the ferromagnetic member and the permanent
magnet acts, at an intensity inversely proportional to the
square of the distance between the ferromagnetic member and
the permanent magnet, as an assist force for assisting in
the clockwise switching drive force provided by the
compressed springs 35 and 36 made of the shape memory
alloy, whereby the clockwise turning movement of the
switching-type indicating means 10 is accelerated so that
it advances at a stroke. Finally, the ferromagnetic member
(the abutment projection 14d) and the permanent magnet (the
clockwise turning-movement stopper 22R) are put into
abutment against each other and in this manner, the
clockwise turning movement of the switching-type indicating
means 10 is finished. At this time, light from a headlight
of an automobile or the like is reflected in a direction
toward the light source, i.e., the headlight by the side
strip faces 11. Thus, the indications of "travel" and
"caution" can be visually confirmed by the presence of the
side strip sign faces 11. Consequently, a driver can
travel the car, while confirming the presence of an end of
a road by the presence of the side strip sign faces 11.
-
When the temperature of the outside air is dropped
down to equal to or lower than the substantially freezing
temperature, the density of each of the turns of the
compressed springs 35 and 36 made of the shape memory alloy
with the shape memorized is reduced at the second preset
temperature in the range of 1 to 2°C and hence, the
resilient force of the springs 35 and 36 in the compression
direction, i.e., the repulsive force for moving the movable
member 40 rightwards as viewed in Fig.13 is reduced.
Therefore, the resilient force of the compressed springs 35
and 36 made of the shape memory alloy in the compressed
direction is smaller than that of the compressed springs 30
and 31 in the compressed direction and hence, the
compressed springs 35 and 36 are expanded, and the movable
member 40 is moved leftwards as viewed in Fig.13 by the
resilient force of the compressed springs 30, 31. Thus,
the switching-type indicating means 10 is turned through
approximately 120 degree from the state shown in Fig.9a to
the state shown in Fig.9b and as a result, the freeze sign
faces 12 are turned to the side of the transparent plate 41
of the housing 4. When this leftward turning movement of
the switching-type indicating means 10 is started, the
ferromagnetic members (the abutment projections 14c) of the
temperature-responsively operated drive mechanism 29 are
moved gradually toward the permanent magnets (the
counterclockwise and clockwise turning- movement stoppers
22L and 22R), as shown in Fig.14, and a magnetic force
between both of the ferromagnetic member and the permanent
magnet acts at an intensity inversely proportional to the
square of the distance between the ferromagnetic member and
the permanent magnet to weaken the resilient force of the
compressed springs 35 and 36 made of the shape memory
alloy, and acts as an assist force for assisting in the
counterclockwise switching drive force provided by the
compressed springs 30 and 31, whereby the counterclockwise
turning movement of the switching-type indicating means 10
is accelerated so that it advances at a stroke. Finally,
the ferromagnetic member (the abutment projection 14c) and
the permanent magnet (the counterclockwise turning-movement
stopper 22L) are put into abutment against each other and
in this manner, the counterclockwise turning movement of
the switching-type indicating means 10 is finished. At
this time, light from a headlight of an automobile or the
like is reflected in a direction toward the light source,
i.e., the headlight by the freeze sign faces 12. Thus, the
indications of "freeze" and "caution" can be visually
confirmed by the presence of the freeze sign faces 12.
Consequently, a driver can travel the car, while confirming
the freezable state of a road and the presence of a road
end by the presence of the freeze sign faces 12.
Particularly, the driver can confirm the frozen state of a
road surface by perceiving the color of a recurrent
reflected light from the freeze sign faces 12, the shape of
the reflecting faces and the letters on the freeze sign
faces.
-
According to the present invention, when the
operation is conducted upon changing of the temperature of
the outside air between the predetermined temperatures,
i.e., between the first preset temperature in the range of
4 to 5°C to provide the indication of caution to travel and
the second preset temperature in the range of 1 to 2°C or
less to provide the indication of caution to freeze, the
permanent magnets (the clockwise turning-movement stopper
22R and the counter clockwise turning-movement stopper 22L)
and the ferromagnetic members (the abutment projections 14c
and 14d) provide the assist force for assisting in the
switching drive force to the shape memory alloy and the
like providing the switching drive force to the switching-type
indicating mans 10. Therefore, the switching of the
indication at the predetermined temperature corresponding
to the substantially freezing temperature of the switching-type
indicating means 10 can be carried out promptly and
automatically. Thus, it is possible to promptly inform the
driver, the road manager or the like of the freezing of the
road surface occurring in the winter season to ensure the
stability of the road traffic.
-
The drive force-assisting means 50 placed on the
temperature-responsively operated drive mechanism 29
according to the present invention may be constructed by
disposing the permanent magnets and the ferromagnetic
members for providing a magnetic force between the
stationary housing 4 and the movable section comprising the
V-shaped plate member 15, the movable member 40 and the
like in the switching-type indicating means 10. For
example, permanent magnets 51 may be mounted at left and
right ends of the movable member 40, and stoppers 52 made
of a ferromagnetic material may be secured to the lower
attaching member 20, as shown by dashed lines in Fig.13a.
In the disposition of the permanent magnets and the
ferromagnetic members, in addition to the combination of
the above-described permanent magnets (the clockwise
turning-movement stopper 22R and the counterclockwise
turning-movement stopper 22L) and the ferromagnetic members
(the abutment projections 14c and 14d), the permanent
magnets may be placed on the movable member 40, and
ferromagnetic members may be placed on the housing 4. the
magnitude of the magnetic force provided between the
permanent magnet and the ferromagnetic member and the
distance between the permanent magnet and the ferromagnetic
member may be determined properly in accordance with the
design criterion such as the magnitude of the assist force
provided by the drive force assisting means 50, the
position of the movable member 40 in the middle of movement
of the movable member 40, in which the assist force is
required, and the like.
-
In the present embodiment, when the temperature of a
road surface is equal to or lower than the substantially
freezing temperature, the freeze sign faces 12 which are
recurrent reflecting faces of the switching-type indicating
mans 10 are turned to be perpendicular to the road surface,
so that the driver can perceive the recurrent reflection
indication on the freeze sign faces 12. When the
temperature of a road surface is higher than the
substantially freezing temperature, the side strip sign
faces which are recurrent reflecting faces of the
switching-type indicating mans 10 are turned through
approximately 120 degree, so that the driver can perceive
the recurrent reflection indication. Alternatively,
according to the present invention, the compressed springs
35 and 36 made of the shape memory allot and the compressed
springs 30 and 31 may be mounted in the arrangement
opposite from that described above, and in this case, the
recurrent reflection indications on the side strip sign
faces 11 and the freeze sign faces 12 can be reversed.
-
In addition, the difference between the indications
on the recurrent reflection faces can be represented by the
difference between the patterns such as colors, letters,
illustrations and the like by using the difference between
the recurrent reflection indications on the side strip sign
faces 11 and the freeze sign faces 12. For example, the
letters of "caution to freeze", "cation to slip" and
"frozen road" can be represented, and under the opposite
condition, the letters of "caution to travel" can be
represented, as in the reference example showing the
indications of the letters in Fig.4. In other words,
according to the present invention, the recurrent
reflection indications on the side strip sign faces 11 and
the freeze sign faces 12 are not limited to the coloration
of the recurrent reflection faces, and letters may be
formed, or the shape of the recurrent reflection faces may
be figures meaning the freeze.
-
Further, in the present embodiment, the switching-type
indicating means 10 is assembled to the back lid 9
constituting the housing 4 through the lower attaching
member 20 and the upper attaching member 60, leading to an
improved assemblability. However, according to the present
invention, the switching-type indicating means 10 may be
assembled to the case body 8 constituting the housing 4.
Particularly, the switching-type indicating means 10 are
disposed with the temperature-responsively operated drive
mechanism 29 and the upper and lower attaching members 60
and 20 assembled to the flat plate-shaped back lid 9
constituting the housing 4 and hence, the assemblability is
improved, and the confirmation of the characteristic after
the assembling and the like can be easily carried out.
-
The temperature-responsively operated drive
mechanism 29 is not adapted to detect a temperature equal
to or lower than 0°C, but in the freeze-indicating sign
system 1 placed at a location 0.8 to 1m above a road
surface, a good freezing- temperature detecting effect was
obtained by setting a temperature slightly higher than the
freezing temperature of the ground surface from the
relationship between a difference in temperature between a
temperature-detecting point on the freeze-indicating sign
system 1 and the ground surface. However, the temperature
may be set at 0°C or lower than 0°C, depending on the
surroundings of placement of the system such as the traffic
volume, the region such as the mountainous region, the type
of a road surface, the time lag and the like. The shape
memory alloy having a hysteresis temperature in a range of
3 to 4°C, i.e., capable of being restored at 4 to 5°C was
used. When a road surface is once frozen, even if the
temperature of the outside air is raised, the temperature
of the road surface is not raised immediately, and there is
a time lag for the raising of the temperature. However,
this can be corrected by the hysteresis temperature. For
example, it is desirable that the hysteresis temperature is
used in correspondence to the raising of temperature of the
road surface frozen and defrozen at night and the
temperature of the outside air before noon. The
temperature-responsively operated drive means may be
disposed at any portion of the housing 8 and preferably,
can be disposed at any of a lower portion, a side portion,
a back portion and an upper portion capable of detecting
the temperature of the outside air with less time lag.
-
According to the present invention, the recurrent
reflection face can be formed in the form of a small
sphere, a prism face and the like, and the coloration of
reflected light can be achieved by the coloration of the
reflection faces, or by forming the transparent member as a
colored transparent member. The recurrent reflection in
the present embodiment is on the assumption that the angle
of incidence of light and the angle of reflection of light
are parallel to each other, as in a transparent sphere.
According to the present invention, however, the recurrent
reflection does not mean a recurrent reflection in a narrow
sense, and it is obvious that any member may be used in
which the angle of incidence of light and the angle of
reflection of light are parallel to each other, as in a
mirror surface. In addition, it is not required the angle
of incidence of light and the angle of reflection of light
are exactly parallel to each other and hence, basically,
the present invention embraces a case where most of
incident light is reflected as reflected light.
-
The switching-type indicating means 10 in the
present embodiment comprises the side strip sign faces 11
adapted to provide the indication when the temperature is
raised to exceed the first preset temperature, and the
freeze sign faces 12 adapted to provide the indication when
the temperature is dropped to lower than the second preset
temperature lower than the first preset temperature, but
such disposition may be reversed, as described above. The
type of the disposition is determined by setting the second
preset temperature and the hysteresis temperature and
hence, according to the present invention, the side strip
sign faces 11 adapted to provide the indication at a
temperature equal to or higher than the first preset
temperature can be first recurrent reflection faces, and
the freeze sign faces 12 adapted to provide the indication
at a temperature lower than the second preset temperature
can be second recurrent reflection faces.
-
In the above-described embodiment, in the
temperature-responsively operated drive mechanism 29
constructed by the compressed springs 35 and 36 made of the
shape memory alloy and capable of providing the
turning/displacing drive force depending on the temperature
such as the second present temperature, the movable member
40 having the racks 41 meshed with the pinions 14b of the
switching-type indicating means 10, the drive force
assisting means 50 and the like, the expansion and
contraction of the compressed springs 35 and 36 are carried
out by meshing the pinions 14b of the switching-type
indicating means 10 with the racks 41 of the movable member
40. In the temperature-responsively operated drive
mechanism 29 according to the present invention, however,
the compressed springs 35 and 36 may be made of a shape
memory alloy capable of providing a turning/displacing
drive force depending on the temperature such as the second
preset temperature, and a predetermined torque may be
provided directly by the shape memory alloy formed into a
volute-coiled or spirally-coiled shape or of a leaf spring-shape.
Either of the coiled shape and the leaf spring-shape
can be selected depending on the temperature
characteristic and the responsiveness. When the
predetermined torque is provided by the shape memory alloy
formed into a volute-coiled or spirally-coiled shape, the
number of parts is smaller, which is advantageous. Of
course, the shape memory alloy may be used as a heat-responsively
operated means such as a shape memory plastic,
a bimetal and the like. The compressed springs 30 and 31
may be omitted, and only the compressed springs 35 and 36
made of the shape memory alloy may be provided. However,
if the shape memory alloy is used as in the above-described
embodiment, the switching of the contents of the indication
can be conducted rapidly at a temperature near the freezing
temperature of a road.
-
In the upper attaching member 60 in the above-described
embodiment, the upper support section comprising
the upper end shaft 13a, the metal bearing 62 and the slide
ring 63 for supporting the upper end of the switching-type
indicating means 10 rotatably is disposed at the upper
portion of the housing 4, but a ball bearing with balls
rolled on opposite sides of the slide ring 63 may be used.
Namely, the upper support section may be any means adapted
to resist the load of the switching-type indicating means
10 by the surface contact with the upper attaching member
60 and to support the switching-type indicating means 10.
-
The lower attaching member 20 in the above-described
embodiment, the lower support section comprising the lower
end shaft 14a, the projection 21 and the sleeve 23 and
adapted to support the lower end of the switching-type
indicating means 10 and to obtain a rotating force from the
temperature-responsively operated drive mechanism 29 is
disposed at the lower portion of the housing 4. According
to the present invention, however, the lower attaching
member 20 may have a structure in which the lower end of
the switching-type indicating means 10 is restrained so
that it is not moved perpendicularly to the lengthwise
direction thereof, and the rotating force is obtained from
the temperature-responsively operated drive mechanism 29.
-
The embodiment has been described about the case
where the four switching-type indicating means 10 have been
mounted, wherein the four switching-type indicating means
10 are turned by the two compressed springs 30 and 31 and
the two compressed springs 35 and 36 made of the shape
memory alloy on the lower attaching member 20. More
specifically, by only ensuring that the two switching-type
indicating means 10 are turned by a pair of the compressed
spring 30 and the compressed spring 35 made of the shape
memory alloy, the back lid 9 is elongated laterally, the
lengths of the upper and lower attaching members 60 and 20
and the length of the movable member 40 are set at required
values, the freeze-indicating sign system can be increased
in size by increasing the number of the compressed springs
30 and 31 and the compressed springs 35 and 36 made of the
shape memory alloy, i.e., the number of pairs of these
compressed springs without changing of the types of the
compressed springs. Therefore, the temperature
characteristic cannot be varied by the increase in size.
Even in this case, the switching-type indicating means 10
are disposed with the temperature-responsively operated
drive mechanism 29 and the upper and lower attaching member
60 and 20 assembled to the flat plate-shaped back lid 9
constituting the housing 4 and hence, the assemblability is
improved, and the confirmation of the characteristic after
the assembling and the fine regulation of the resilient
strengths of the compressed springs 30 and 31 and the
compressed springs 35 and 36 made of the shape memory alloy
can be carried out easily. Particularly, when the freeze-indicating
sign system is large-sized to indicate letters
or the like, all the switching-type indicating means 10 are
operated in operative association with one another and
hence, the outside appearance of the entire system is
improved, because. In addition, the switching of the side
strip sign faces 11 and the switching of the freeze sign
faces 12 are conducted simultaneously and hence, the
outside appearance during such operation is also improved.
Of course, the switching of and the indication on the side
strip sign faces 11 and the switching of and the indication
on the freeze sign faces 12 can be conducted for every
single letter and every group of letters, using a plurality
of freeze-indicating sign systems having a predetermined
length.
-
Even if the lengthwise length of the switching-type
indicating means 10 is set at any value, as described
above, the variation in load of the switching-type
indicating means 10 does not change the rotational friction
resistance directly. Therefore, the lengthwise length can
be set at any value, and consequently, the enlargement of a
two-dimensional plane can be achieved. Of course, the
enlargement of a two-dimensional plane can be achieved even
by disposing the switching-type indicating means 10 in a
required number of rows such as two or three rows.
-
When the caution to freeze is represented by the
indication of letters or characters or by the indication of
red color, the movable member 40 can be divided into pair
units of the compressed springs 30 and the compressed
springs 35 made of the shape memory alloy, and the
temperature characteristics and the hysteresis
characteristics of the adjacent compressed springs 35 made
of the shape memory alloy can be changed, whereby the
switching of the side strip sign faces 11 and the switching
of the freeze sign faces 12 can be conducted sequentially
in a predetermined direction. Namely, the direction for
conduction the switching sequentially can be specified. Of
course, even when the freeze-indicating sign system is
divided for every letter, the switching of the side strip
sign faces 11 and the switching of the freeze sign faces 12
can be conducted sequentially in a predetermined direction
by changing the temperature characteristics and the
hysteresis characteristics of the adjacent compressed
springs 35 made of the shape memory alloy.
-
In the above-described embodiment, the switching-type
indicating means 10 turnably mounted to the housing 4
is capable of being turned through 120 degree, but
according to the present invention, the angle of turning of
the switching-type indicating means 10 is not limited to
120 degree. For example, each of the switching-type
indicating means 10 mounted to the housing 4 for turning
movement through 120 degree is substantially triangular in
shape, and even if the distance between the adjacent
switching-type indicating means 10 is reduced, an
interference with other switching-type indicating means 10
is not arisen. In addition, the variate of the shape
memory alloy can be reduced, and when a large variate can
be taken, the reliability can be enhanced correspondingly.
-
In the switching-type indicating means 10 in the
above-described embodiment, the side strip sign faces 11
adapted to provide the indication at the temperature equal
to or higher than the first preset temperature are first
recurrent reflection faces, and the freeze sign faces 12
adapted to provide the indication at the temperature lower
than the second preset temperature are second recurrent
reflection faces. According to the present invention,
however, when the indicating faces are larger, it is
suitable that the second recurrent reflection faces can be
maintained as the freeze sign faces 12, the indication of
freeze and the indication of information other than freeze
can be distinguished from each other by describing various
information such as a road situation other than the freeze,
a geographical guidance, a local information, a commercial
information and the like on the side strip sign faces 11
adapted to provide the indication at the temperature equal
to or higher than the first preset temperature. If one or
more letters, figures or characters creating the caution to
freeze are provided on the second recurrent reflection face
comprising the freeze sign face 12, so that words
representing the caution to freeze are indicated by the
letters, figures or characters on the adjacent indicating
plates, the number of letters to be indicated is not
increased and hence, it is not necessary to increase the
size of the freeze-indicating sign system.
-
In the freeze-indicating sign system in the above-described
embodiment, the switching-type indicating means
10 are hung vertically from the upper support section of
the upper attaching member 60, but even if the switching-type
indicating means 10 are supported horizontally, the
burden of the load taken by the bearings on the opposite
sides can be reduced to half, and an stable operation can
be expected.
-
Therefore, In such an embodiment, the switching-type
indicating mans 10 may be disposed between the side
attaching members and hence, first recurrent reflection
faces and second recurrent reflection faces comprising side
strip sign faces 11 having any length can be formed by
increasing the number of the switching-type indicating mans
10 disposed in the longitudinal direction. The weight of
the switching-type indicating mans 10 is supported at its
opposite ends and hence, the load is reduced to half. Even
if the length of the switching-type indicating mans 10 is
increased, the switching-type indicating mans 10 can be
turned in such a manner that the contact frictional
resistance is not influenced largely by the length, and the
wearing at horizontally supported points can be reduced,
and hence, the lengthwise dimension of the switching-type
indicating mans 10 can be increased. Therefore, it is
possible to accommodate a two-dimensional increase in size
without an increase in amount of temperature-responsively
operated drive mechanism displaced, i.e., an increase in
energy for driving the compressed spring 35 made of the
shape memory alloy, which forms the pair with the
compressed spring 30.
-
Although the embodiments of the present invention
have been described in detail, it will be understood that
the present invention is not limited to the above-described
embodiments, and various modifications in design may be
made without departing from the spirit and scope of the
invention defined in claims.