U.S. patent number 3,896,925 [Application Number 05/402,280] was granted by the patent office on 1975-07-29 for braking system for an electrically-operated road such as an escalator.
This patent grant is currently assigned to Hitachi, Ltd.. Invention is credited to Takeji Hiramoto, Mitio Imanaka, Tsuyoshi Mitsui.
United States Patent |
3,896,925 |
Mitsui , et al. |
July 29, 1975 |
Braking system for an electrically-operated road such as an
escalator
Abstract
In an electrically operated road, such as an escalator, a
braking force for stopping the electrically operated road is
changed according to whether the running direction is upwardly or
downwardly, so that the braking deceleration of the road during
emergency stopping of operations will become independent of the
running direction of the electrically operated road.
Inventors: |
Mitsui; Tsuyoshi (Katsuta,
JA), Hiramoto; Takeji (Katsuta, JA),
Imanaka; Mitio (Katsuta, JA) |
Assignee: |
Hitachi, Ltd. (Tokyo,
JA)
|
Family
ID: |
26373403 |
Appl.
No.: |
05/402,280 |
Filed: |
October 1, 1973 |
Foreign Application Priority Data
|
|
|
|
|
Sep 29, 1972 [JA] |
|
|
47-96993 |
Mar 28, 1973 [JA] |
|
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48-34574 |
|
Current U.S.
Class: |
198/323; 198/326;
188/171 |
Current CPC
Class: |
B65G
43/06 (20130101); F16D 49/16 (20130101); F16D
59/02 (20130101); B66B 29/00 (20130101); F16D
2121/22 (20130101) |
Current International
Class: |
B66B
29/00 (20060101); F16D 59/02 (20060101); F16D
49/16 (20060101); F16D 59/00 (20060101); F16D
65/14 (20060101); B65G 43/06 (20060101); F16D
49/00 (20060101); B65g 043/06 () |
Field of
Search: |
;198/232,16R,16MS
;188/171,173 ;187/73 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schacher; Richard A.
Assistant Examiner: Thomson; Richard K.
Attorney, Agent or Firm: Beall, Jr.; Thomas E.
Claims
What is claimed is:
1. A braking system for a power-operated road means for
transporting passengers along a vertical component of running,
comprising: first means for producing a running direction signal
correlated to the running direction of said power-operated road
means; emergency switching means for automatically generating an
emergency signal when an emergency condition occurs when said road
means should be secured against movement; braking means for
generating braking force acting to stop said power-operated road
means in response to said emergency signal from said emergency
switching means; and said braking means including brake force
control means, providing an ascent braking force in response to the
running direction signal from said first means indicating an ascent
road running and providing a descent braking force substantially
greater than said ascent braking force in response to the running
direction signal from said first means indicating a descent road
running.
2. A braking system for the road means in accordance with claim 1,
wherein said braking means has at least one auxiliary braking means
and a main braking means; and said braking force control means
operates only said main braking means in response to said first
means indicating an ascent road running, and operates both said
main and auxiliary braking means in response to said first means
indicating a descent road running.
3. A braking system for the road means in accordance with claim 1,
including a prime mover for driving the power-operated road; said
braking means including a rotatably mounted drum drivingly
connected to said prime mover, brake shoe means mounted for
movement into and out of engagement with said drum for producing
the braking force, lever means having a first closed position
holding said brake shoes in engagement with said drum to produce
the braking force and having a second opened position holding said
brake shoes out of frictional engagement with said drum, spring
means biasing said lever means into its closed position,
electromagnetic means for producing a force upon said lever means
in opposition to said spring bias to move said lever means from its
closed position to its opened position against said spring bias,
and second switching means for selectively energizing said
electromagnetic means when there is no emergency signal being
produced by said emergency switching means and for deenergizing
said electromagnetic means in response to an emergency signal from
said emergency switching means; and said braking force control
means changing the force supplied by said spring means
automatically in response to the running direction signal produced
by said first means.
4. A braking system for the road means in accordance with claim 3,
wherein said spring means includes at least one spring having
opposite ends respectively acting between a reference portion and
said lever means, and said braking force control means
automatically changing the position of the reference portion in
response to said running direction signal.
5. A braking system for the road means in accordance with claim 3,
wherein said spring means includes a main spring acting upon said
lever means and at least one auxiliary spring acting upon said
lever means, and said braking force control means applying a lesser
number of springs to act upon said lever means during ascent that
are applied during descent.
6. A braking system for the road means in accordance with claim 5,
wherein said power-operated road means is an escalator, said prime
mover is an electric motor, including power switching means
selectively connecting said electric motor to a power supply for
running said electric motor in opposite directions.
7. A braking system for the road means in accordance with claim 1,
wherein said braking force control means includes an electric delay
circuit for automatically delaying a predetermined period of time
after the application of the ascent braking force during ascent
running sufficiently for stopping the road and immediately
thereafter increasing the braking force to resist downward slipping
of the stopped road means under load.
8. A braking system for the road in accordance with claim 1,
wherein said braking means includes a spring for producing the
braking force and electromagnetic means for preventing the
application of the spring braking force; and said braking control
means changes the force of said spring according to the running
direction.
9. A braking system for the road means in accordance with claim 8,
wherein said braking means includes a brake shoe and a lever
extending between one end of said spring and said brake shoe; and
said braking force control means including reference abutment
engaging the opposite end of said spring, a stationarily mounted
threaded shaft, a nut threadably engaged and rotatably mounted on
said shaft in abutting axial engagement with said reference
abutment, a reversible electric motor, and a gear drivingly
connected to said reversible electric motor and in inter-meshing
engagement with said nut.
10. A braking system for the road means in accordance with claim 1,
wherein said braking means includes a brake shoe, a pivotally
mounted lever means for engaging said brake shoe, spring means for
applying a spring bias to said lever means in the direction for
applying the braking force and further for producing the braking
force, and first and second electromagnetic means, each for
engaging said lever means and for moving said lever means against
said spring bias out of braking shoe engagement when energized;
said braking force control means deenergizing only one of said
electromagnetic means under emergency conditions in the ascent
running direction and deenergizing both of said electromagnetic
means under emergency conditions in the descent direction.
11. A braking system for the road means in accordance with claim 1,
wherein said braking means includes a brake shoe, a pivotally
mounted lever means for engaging said brake shoe, spring means for
applying a spring bias to said lever means in the direction for
applying the braking force and further for producing the braking
force, and electromagentic means having two axially aligned movable
core portions within one magnetic field producing means; said
electromagnetic means having first tie rod means attached to one of
said portions, extending through the other of said portions and
being drivingly connected to one end of said spring means, and
second tie rod means attached to the other of said portions,
extending through said one portion and being drivingly connected to
the other end of said spring means.
12. A braking system for the road means in accordance with claim 1,
including a prime mover for driving the power-operated road means
and braking means including a rotatably mounted member drivingly
connected to said prime mover for rotation with running of said
power-operated road means, brake shoe means mounted for movement
into and out of engagement with said rotatable member for producing
the braking force, first spring means biasing said brake shoe means
toward said rotatably mounted member; first electromagnetic means
for holding said brake shoe means out of engagement with said
rotatably mounted member against the bias of said first spring
means when energized, and when not energized permitting said first
spring means to move said brake shoe means into engagement with
said rotatably mounted member; second spring means for biasing said
brake shoe means into engagement with said rotatably mounted member
to produce a braking force in addition to the braking force
produced by said first spring means biasing said brake shoe means
into engagement with said rotatably mounted member; second
electromagnetic means preventing the application of the spring bias
of said second spring means to said brake shoe means when energized
and permitting the application of the spring bias of said second
spring means in the direction of engagement of said brake shoe
means and said rotatably mounted member when deenergized; and said
braking force control means normally energizing both of said first
and second electromagnetic means in the absence of an emergency
signal, deenergizing said first electromagnetic means and
maintaining said second electromagnetic means energized in response
to an emergency signal from said emergency switching means and a
running direction signal from said first means indicating an ascent
road running, and deenergizing both of said first and second
electromagentic means in response to an emergency signal from said
emergency switching means and a running direction signal from said
first means indicating a descent road running, so that only the
bias of said first spring means is applied to produce the braking
force between said braking shoe means and rotatably mounted member
under emergency conditions during ascent and further so that the
spring bias of both said first and second spring means is applied
to produce a correspondingly larger braking force between said
brake shoe means and said rotatably mounted member under emergency
conditions during descent.
13. A braking system for the road means in accordance with claim
12, wherein said braking force control means includes an electric
delay circuit for automatically delaying a predetermined period of
time after the application of the ascent braking force during
ascent running sufficiently for stopping the power-operated road
means and immediately thereafter deenergizing both said first and
second electromagnetic means for applying the spring bias of both
said first and second spring means under emergency conditions to
resist downward slipping of the emergency stopped power-operated
road means under load.
14. A braking system for the road means in accordance with claim
12, wherein said brake shoe means includes a brake shoe drivingly
connected to a pivotally mounted lever mounted for movement between
an opened position out of engagement with said rotatably mounted
member and a closed position in engagement with said rotatably
mounted member; said first spring means directly engaging said
lever to bias it towards said rotatably mounted member in both said
opened and closed positions; said first electromagnetic means
directly engaging said lever to move it from its closed position to
its opened position when energized against the bias of said first
spring means; said second electromagnetic means holding said second
spring means out of engagement with said lever in both said opened
position and closed position when energized and applying the spring
bias of said second spring means only when deenergized by
permitting engagement of said second spring means with said lever
in both said opened and closed positions.
15. A braking system for the road means in accordance with claim
12, wherein said brake shoe means includes two brake shoes engaging
opposite sides of said rotatably mounted member, two levers
drivingly connected respectively to said two brake shoes and being
pivotally mounted for movement between opened and closed positions;
and wherein said first spring means engages between said levers to
simultaneously bias them towards their closed position, said first
electromagnetic means engages between said levers to simultaneously
drive them from their closed position to their opened position
against the bias of said first spring means, and said second spring
means and second electromagnetic means applying the bias of said
second spring means simultaneously to said levers when said second
electromagnetic means is deenergized and completely removing the
bias of said second spring means when said second electromagnetic
means is energized in both of said opened and closed positions.
16. A braking system for the road means in accordance with claim
15, wherein said braking force control means includes an electric
delay circuit for automatically delaying a predetermined period of
time after the application of the ascent braking force during
ascent running sufficiently for stopping the power-operated road
means and immediately thereafter deenergizing both said first and
second electromagnetic means for applying the spring bias of both
said first and second spring means under emergency conditions to
resist downward slipping of the emergency stopped power-operated
road means under load.
17. A braking system for the road means in accordance with claim
15, wherein said levers are pivotally connected together, said
brake shoes and at least one of said first and second spring means
and at least one of said first and second electromagnetic means are
mounted on the same side of the pivots of said levers.
18. A braking system for the road means in accordance with claim
17, wherein the other of said spring means and the other of said
electromagnetic means are mounted on the same side of the lever
pivots as said brake shoes.
19. A braking system for the road means in accordance with claim
17, wherein the other of said spring means and the other of said
electromagnetic means are mounted on the opposite side of the lever
pivots from said brake shoes.
20. A braking system for the road means in accordance with claim
17, wherein the pivotal connection between said levers is provided
by link means pivotally connected at one end to one of said levers
and at its opposite end to the other of said levers; said first
spring means comprising a rod on the opposite side of said
rotatably mounted member from said link means and being secured at
one end to one of said levers and having a spring abutment at its
opposite end, and a compression spring between said spring abutment
and the other of said levers; said first electromagnetic means
having a single electromagnetic coil, a first core member movably
mounted within said coil and drivingly connected to one of said
levers and a second core member movably mounted within said coil
and drivingly connected to the other of said levers; said
electromagnetic coil being mounted between said levers on the same
side of said rotatably mounted member as said first spring means;
the driving connection between each of said movably mounted core
members and its respective lever comprising at least one rigid rod
fixedly connected at one end to its respective core member, fixedly
connected at its opposite end to its respective lever and
intermediate said ends extending through the other of said core
members.
21. A braking system for the road means in accordance with claim
20, wherein said second spring means is a coil compression spring,
and wherein said second electromagnetic means includes an
electromagnetic coil, two separate core members movably mounted
with respect to each other and with respect to said coil and being
mounted within said coil for axial movement in the axial direction
of said coil spring, a rod drivingly connected at one end to one of
said core members and at its opposite end to one end of said coil
spring for compressing said coil spring upon movement of the core
members into said coil upon energization of said coil; said core
members and coil being positioned between said levers.
22. A braking system for the road means in accordance with claim
21, wherein said second electromagnetic means includes a second rod
drivingly connected at one end to the other of said core members
and at its opposite end to the other end of said coil spring for
further compressing said coil spring when said other core member
moves into said coil upon energizing the coil.
23. A braking system for the road means in accordance with claim
21, wherein said second electromagnetic means includes a second
coil compression spring on the opposite side of said coil and core
members from said first mentioned coil spring, and a second rod
drivingly connected at one end to the other of said core members
and drivingly connected at its opposite end to the second coil
spring; means drivingly connecting the ends of both of said coil
springs opposite from their connection with their respective rods
to the opposite axial ends, respectively, of said electromagnetic
coil.
Description
BACKGROUND OF THE INVENTION
The present invention relates systems braking system for an
electrically operated road, such as an escalator.
In general, the floor height of an escalator for use at, for
example, a transport station having very large facilities, unlike
the level difference of the usual department store, office building
or the like, will have a level difference between the platforms of
the station and the ground that may be well over 10 meters when the
urban traffic network is divided into a suitable grid.
In order to relieve crowdedness at the morning and evening rush
hours, a high speed escalator has recently been desired.
Additionally, the relationship between passengers riding on
upwardly moving escalators and downwardly moving escalators in the
morning is quite different than the relationship in the evening.
For example, if we assume that in the morning most of the
passengers will be riding upwardly on the escalators at a
particular station, then it will follow that in the evening most of
the passengers will be riding downwardly on this same group of
escalators at the station. In this case, some of the escalators
that will be operating as upwardly moving escalators in the morning
will be switched over to operate as downwardly moving escalators in
the evening by merely reversing the direction of escalator
running.
If a conventional escalator is subjected to emergency stopping
while it is running in the upward direction with a large number of
passengers, where will be a great amount of shock to the passengers
so that they are most likely to fall down from the sudden stopping
of the escalator, because the total weight of the passengers tends
to stop the operation of the escalator, that is, the total weight
of the passengers will add to the braking force. On the other hand,
if this same conventional escalator were operated in the reverse
direction to run downwardly, the total weight of the passengers
would tend to keep the escalator moving downwardly and be
subtracted from the conventional braking force, so that the
significance of the emergency stop would be lost and the escalator
would not stop sufficiently rapidly. This tendency is increased
with a corresponding increase in total height spanned by the
escalator and by an increase in the speed of the escalator.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to overcome
the above mentioned disadvantages of the prior art and to provide
an emergency braking system suitable for a high speed escalator
whose running direction over a great difference in height is
changed frequently. It is particularly desirable to provide such a
system with an emergency braking system that will have a braking
deceleration that will be kept constant independently of the
running direction.
In the present specification, an electrically operated road means
will mean a type of conveyor that will include both an escalator
having steps and a moving road installed for a similar purpose to
that of the escalator and having an inclination, but no steps.
When an electrically operated road, such as an escalator, is used
to run upwardly, the total passenger weight will tend to increase
the braking force for stopping the escalator. Thus, the emergency
stopping of a conventional escalator will have a large deceleration
that will exceed the limitation imposed by the safety and comfort
of the passengers, so that the passengers will not be able to
maintain their positions upon emergency stopping. In the present
invention, a driving force of the escalator will have a large
inertia in order to keep the deceleration of the emergency stop at
a suitable value independently of the passenger weight.
On the other hand, if the electrically operated road is used as a
downwardly moving road, the large inertia of the driving device
will decrease the braking force. The braking system of the present
invention has a braking force control means that will change the
braking force in accordance with whether the running direction is
upwardly or downwardly, in order to keep the deceleration of the
electrically operated road at a suitable value for the comfort and
safety of the passengers.
A conventional type of escalator has a spring that will apply the
braking force. Therefore, it is desirable according to the present
invention to change or control this type of spring force for
controlling the braking force of the escalator. Although an
escalator will be mentioned as a specific example, it is to be
understood that as mentioned above, there are other types of
devices with which the present invention may be useful, according
to the broader aspects of the present disclosure. This spring force
may be changed by changing the length or compression or tension of
the spring according to the running direction. The spring force of
a compression spring that is acting as the brake force may be
increased by compressing the spring.
As a further example of the present invention, the braking system
may comprise a main spring and an auxiliary spring for causing the
braking force. During upward movement of the electrically operated
road, only the main spring would be used for causing the braking
force, and no auxiliary spring would be used. When the electrically
operated road moves in the downward direction, both the main spring
and the auxiliary spring would be used for causing the braking
force in order to keep the deceleration of the emergency stop at a
suitable value independently of the running direction.
Further, it is possible to have a plurality of auxiliary springs.
In this case, the braking force can be controlled in response to
the number of passengers by changing the number of the effective
springs creating the braking force according to the number of
passengers that the escalator in carrying in addition to changing
the braking force in accordance with the running direction.
BRIEF DESCRIPTION OF THE DRAWING
Further objects, features and advantages of the present invention
will become more clear from the following detailed description of
the drawing, wherein:
FIG. 1 is a schematic view showing a portion of a conventional
escalator driving section;
FIG. 2 is a plan view of a portion of a conventional escalator
drive taken along line II--II of FIG. 1;
FIG. 3 is a diagram showing a typical relationship between the
deceleration of an emergency stop and the passenger load;
FIG. 4 is an enlarged cross sectional view of a part of the braking
system according to an embodiment of the present invention;
FIG. 5 is an electric circuit diagram for the braking system of
FIG. 4;
FIG. 6 shows a further embodiment of the present invention;
FIG. 7 is an enlarged view of a portion of FIG. 6;
FIG. 8 is a cross sectional view taken along line VIII--VIII of
FIG. 6;
FIG. 9 is a sectional view taken along line IX--IX of FIG. 6;
FIG. 10 is a side elevation view of the braking system according to
FIG. 6;
FIG. 11 is a plan view of a modification of the braking system of
FIG. 6;
FIG. 12 is a side elevation view of the braking system according to
the modification of FIG. 11; and
FIG. 13 is a control circuit diagram according to another
embodiment of the control circuit.
DETAILED DESCRIPTION OF THE PRIOR ART
The conventional or prior art type of escalator 1 as shown in FIG.
1 will transport passengers between an upper floor and a lower
floor in such a way that power derived from the electric motor 2
and the transmission 3 will, by means of the endless chain 4, drive
the wheel or sprocket 5. This large diameter sprocket 5 is
drivingly connected to the slightly smaller diameter sprocket or
wheel 6 that is used to in turn drive the endless array of steps 7
that are secured in a conventional manner to the footboard chain 8,
which chain 8 is drivingly connected to the sprocket 6. During
their endless travel, the steps 7 will travel along and be
supported by the rail 9. The escalator may be braked, particularly
upon emergency conditions, by means of the brake 10 that is
provided at the head of the electric motor 2.
The details of the brake may be seen in FIG. 2, which is a plan
view of a portion of FIG. 1 taken along line II--II. As seen in
FIG. 2, shoes 14 are provided on right and left hand levers 13. A
brake drum 12 is drivingly mounted on the main shaft 11 of the
motor 2, to be braked frictionally by the forces of the springs 15
that will tend to move the levers 13 and the shoes 14 carried
thereby into radial engagement with the brake drum 12. The shoes 14
are opened, that is moved away from and out of contact with the
brake durm, by means of the electromagnet 16 during running of the
escalator, by the electromagnet 16 pulling the upper (as seen in
FIG. 2) ends of the levers 13 inwardly and by providing the
indicated stationary pivots between the points of connection of the
electromagnet 16 and the brake shoes 14, so that the levers 13 will
be first class levers. When the power source is disconnected, or
when otherwise the electromagnet 16 is deenergized, the magnetic
force of the electromagnet 16 will effectively disappear and the
braking force due to the springs 15 will be exerted on the brake
drum 12, as the shoes 14 will pivot inwardly.
In the structure of such a conventional braking system, the
pressure of the springs 15 will be set at a predetermined value by
means of the indicated lock nuts, and thereafter this value will be
constant or unchanged. For this reason, as has been stated
previously, especially when the floor height or running height is
large and the running speed is quite high, the braking distance and
deceleration will be greatly dependent on the direction of running,
os that the difference between these characteristics for opposite
runs will be remarkably high to cause considerable inconvenience
and danger to the passengers.
With reference to FIG. 3, the braking deceleration or shock upon
emergency stop of the escalator, from the viewpoint of safety and
comfort for the passengers, must be limited so as to always have a
value within a range from the upper limit S.sub.1 and the lower
limit S.sub.2, independently of the magnitude of the load of the
passengers and the direction of running. In the diagram of FIG. 3,
the upper limit value S.sub.1 is the maximum value of the safe
braking shock (deceleration) at which the passengers are prevented
from experiencing undesirable effects, such as falling. S.sub.2 is
the lower limit set for the braking distance, since if the braking
distance is very long as would be caused by a small deceleration
during emergency stop, the function of the emergency stop would not
be effected.
With the braking system of a conventional system wherein the brake
force applied would always be constant regardless of running
direction, it would be seen that if an emergency stop of the
escalator were made under the conditions of a large floor height
with passengers, it would be impossible to bring the deceleration
or stopping shocks in both directions of ascent and descent within
the safe range. More specifically, if the spring force is set so
that the braking shock may not become lower than the lower limit
value S.sub.2 during descent running, then the shock value becomes
a for zero or no passenger load during descent running. With
increase in the passenger load, the shock or deceleration value
will decrease, that is the braking distance will become longer, as
illustrated by the straight line D.sub.1. Even at 100 percent load,
the deceleration or shock, as determined by lined D.sub.1, will not
become lower than the lower limit value S.sub.2. The braking shock
during ascent running, however, will increase with increase in the
passenger load as illustrated by the straight line U.sub.1. At the
load of 100 percent during ascent, it is seen that the shock or
deceleration as determined by line U.sub.1 would be far beyond the
upper limit value S.sub.1, and would present a dangerously high
braking shock.
On the other hand, if the spring force of the conventional system
were set so that the braking shock value or deceleration would not
exceed the upper limit value S.sub.1 even for passenger load of 100
percent during ascent running, the braking shock would be at b
under the no load or no passenger condition and increase with
increase in load as illustrated by the dot-dash line U.sub.2 and
become equal to or lower than the upper limit value S.sub.1 at 100
percent load. During descent running, the braking distance would
become longer as the deceleration would decrease as shown by the
line D.sub.2, and for higher loads up to 100 percent, the
deceleration would fall far below the lower limit value S.sub.2, so
that the purpose of the emergency stop would not be attained.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
In view of the above and deficiencies of the conventional system,
the present invention has as a purpose and result the maintaining
of the shock values or deceleration within the range S.sub.1 to
S.sub.2 for braking during both ascent and descent. The present
invention relates not only to escalators but also to electrically
moving roads, although the present invention will be described with
specific reference to escalators for purposes of the preferred
embodiment.
An embodiment of the present invention as shown in FIG. 4 would be
used to replace the spring 15 of FIG. 2, for urging the brake shoe
levers toward the brake drum of an otherwise conventional escalator
as shown in FIG. 1. Accordingly, elements that are common with the
conventional system will not be described in detail or shown
further in the drawing.
In FIG. 4, the conventional brake lever 13 is urged into braking
engagement by the brake spring 15, which brake spring 15 is held at
its opposite end by means of a thrust bearing 17 that is provided
for transmitting axial forces while allowing rotation between the
brake spring seat 18 and a rotatably mounted gear 19. When the
servomotor 21 is rotated, it will drive a small diameter and
elongated pinion 22 for rotation, so that the gear 19 that is
meshed therewith will be driven rotatably about its axis and moved
in the horizontal direction of the drawing by means of a helical
screw thread connection between the gear 19 and the shaft 20 on
which it is mounted. Thus, the compression length of the spring 15
may be changed to accordingly change its spring force.
The threaded shaft 20 will extend horizontally through the spring
15, the spring seat 18, the lever 13, and the other elements as
indicated. This shaft 20 has a square thread K for providing
rotatable threaded interengagement with the gear 19, which acts as
a nut, and for preventing rotation between the shaft 20 and spring
seat 18. A fitting 23 is rigidly secured to the housing of the
motor 21 to be stationary therewith. The shaft 20 is stationarily
mounted by means of the fitting 23 and a lock nut 24 that engages
an outer machine screw thread T of the shaft 20.
The end of the shaft supporting the pinion 22 that is opposite from
the motor 21 is rotatably supported by means of a bearing 25, which
is mounted together with the servomotor 21 on the head of the
escalator motor 2 as in the prior art brake 10 of FIG. 1.
A bracket 26 is rigidly secured to the spring seat 18 so that it
will have only horizontal reciprocating motion as indicated by the
arrows along with the spring seat 18. The bracket 26 is provided at
one extreme end with a projecting or operating piece 28 that will
engage the stationary contacts 31 and 33 of switches 32, 34,
respectively. A bracket 30 is provided as shown for mounting the
switches 32 and 34 stationarily in spaced relationship, with the
bracket 30 having an opening therein for passing the outer end of
the rod 20, so that the bracket 30 may be clamped and fixed between
the fitting 23 and the lock nut 24.
FIG. 4 illustrates in solid lines the setting of the spring 15 for
descent or downward running of the escalator. To reach this state,
the gear 19 has been moved rightward as viewed in FIG. 4 by
operation of the servomotor 21 to compress the spring 15 to a
greater extent than would be provided for upward running. During
such adjustment, the operation of the servomotor 21 would continue
until the contact 31 of the switch 32 would be depressed by the
operating piece 28 to thereby break the circuit for the servomotor
and prevent further rotation of the gear 19. The amount of
compression of the spring 15 can accordingly be easily varied by
adjusting the stationary position of the switch 32.
If it is desired to operate the escalator for ascent or upward
running after it has been operating in the descent condition as
shown in solid lines in FIG. 4, a suitable control which operate
the servomotor in the reverse direction so as to move the gear 19
toward the left in FIG. 4. Accordingly, the spring 15 would be
increased in length or loosened to reduce its spring force. The
gear 19 would be moved leftward into the position indicated by the
dot-dash lines at which position the contact 33 of the switch 34
would be depressed by the operating piece 28 to break the circuit
to the servomotor and accordingly prevent further movement of the
gear 10. Thus, the spring force for the left hand descent position
would be less than for the right hand ascent position. Thus,
emergency stopping would be safe regardless of whether the
escalator were moving upwardly or downwardly, because the spring
force would be relatively small for upward movement and relatively
large for downward movement.
Both the length of the square thread K by which the gear 19 is
fitted onto the rod 20 and the length of the pinion 22
corresponding to the amount of movement of the gear 19 will be
determined by the desired braking forces that will be respectively
required for the two running directions of the escalator to
maintain satisfactory braking conditions.
An interlocking mechanism for the running direction of the
escalator and the brake force varying device will now be explained
in conjunction with an electric circuit as shown in FIG. 5. When a
key switch K.sub.1 is switched on, a main contact A.sub.0, a
holding contact A.sub.1 and a control contact A.sub.2 are closed by
energization of the coil A. If the switch K.sub.2 for the running
direction is switched to the "UP" side, a coil B is energized to
close contacts B.sub.1, B.sub.2, B.sub.3 and B.sub.4 of the circuit
for the brake G. As the result, the braking force exerted by the
spring is released and the motor 2 will start for the ascent
running upon closure of the main contacts B.sub.0, and D.sub.0.
Since a contact B.sub.3 is closed to energize a coil Z, a contact
Z.sub.1 of the circuit for the servomotor will be closed. If the
spring 15 is in the compressed state as shown in FIG. 4, the gear
19 being located at the right hand position of FIG. 4, current for
the servomotor 21 will be provided by the sequence of contacts
X.sub.2, servomotor 21, contact X.sub.4, contact Z.sub.1, switch
34. Thus, the servomotor 21 will be rotated so as to move the gear
19 in the left hand direction of FIG. 4 so that the contact 31 of
the switch 32 will be released as the operating piece 28 is moved
leftward out of engagement with the contact 31 so that the switch
32 will be turned on. When the operating piece 28 reaches the
contact 33 and engages it, the switch 34 will be turned off to
break the circuit to the servomotor 21 and prevent further
rotation. Thus, the spring 15 will be loosened to establish a
spring setting that will impart the appropriate braking force for
ascent running.
On the other hand if the spring 15 is in position for ascent
running when the escalator is operated in the up direction, the
servomotor 21 will not be operated as the circuit is broken by the
switch 34. However, if it were then decided to operate the
escalator for descent running, the switch K.sub.2 would be moved to
the "DN" position to energize the coil C for closing of the holding
contact C.sub.1 and the control contacts C.sub.2 and C.sub.3. A
main contact C.sub.0 would be closed and a contact C.sub.4 of the
brake circuit would be closed to release the brake. Thus, the
escalator would be started for descent running. Since the contact
C.sub.3 is closed, the coil X will be energized to close contacts
X.sub.1, X.sub.3 and X.sub.5 in the circuit of the servomotor 21
and to open the contacts X.sub.2 and X.sub.4. As a result, current
through the servomotor flows in the opposite direction to that of
ascent running, so that the servomotor will operate in the opposite
direction of rotation. Therefore, the gear 19 would be moved in the
right hand direction for compression of the spring 15 until the
switch 32 would be turned off for interrupting flow of current to
the servomotor 21. Thus, an appropriate set value for the spring
force of the spring 15 would be obtained for descent running.
As described above, in accordance with the present invention, the
amount of the compression of the spring 15 can be changed in
accordance with the running direction of the escalator. The braking
shock or deceleration for emergency stops is thereby made so as to
be represented by the straight line U.sub.2 for ascent running and
by the straight line D.sub.1 for descent running as has been
explained previously with respect to FIG. 3. It is thus seen that
the braking shocks during emergency stops will always fall within
the allowable range S.sub.1 - S.sub.2, which is safe for the
passengers, regardless of the load and running direction.
The foregoing is the explanation of one embodiment of the present
invention. In summary, the present invention is concerned with an
escalator for large floor height or the like structure which
changes the spring force of the emergency brake in accordance with
the running direction of the escalator to thus provide a variable
braking force that will provide braking shocks or deceleration that
will be safe to passengers during emergency stopping with respect
to both running directions.
In accordance with the present invention, even in the case where
the escalator is stopped when it is loaded with a large number of
passengers, the braking shock dependent on the running direction
thereof can always be restrained to a safe range. In addition, the
braking force can also be freely varied in dependence on the
magnitude of the floor height by changing the positions of the
foregoing switches 32, 34, which may be provided with adjustable
mountings on the bracket 30. It is therefore possible to always
keep the shock for the passengers within the safe range during
emergency stops.
Another embodiment of the present invention is shown in FIGS. 6, 7,
8, 9, 10, 11, and 12. Only those portions that differ from the
foregoing embodiment will be described in detail and it is readily
apparent how the structure of the second embodiment may be employed
with the otherwise conventional escalator of FIGS. 1 and 2.
As shown in FIG. 6, a brake drum 612 is fixedly secured on the main
shaft 611 of the motor and is frictionally braked by the
application of shoes 614 that are mounted on right and left hand
levers 616 and 618, respectively. To one side of the shoes, the
levers are pivotally mounted to each other and to the other side of
the shoes the levers are secured to a main magnetic coil 630 and an
auxiliary magnetic coil 632. Each of these coils has moving
portions 620, 622 which are attracted or moved by energization of
each coil and which will thereby open the levers 616, 618 against
the force of springs 624, 626 so as to separate the shoes 614 from
the drum 612. A rod 628 extends through a hole that is provided in
the centers of the moving portions 620, 622 of the auxiliary coil
632, as shown in more detail in FIG. 7, and two holes of each left
end of the levers 616, 618. The upper end of the rod 628 is
provided with a spring 626, one end of which engages a stop 634
secured to the shaft 628 by a nut, and the other end of which
engages a cross piece 636 that is mounted on bolts 640, 642, which
bolts are fixedly mounted at their opposite ends to a cross plate
644. The plate 644 is mounted by push bolts 646, 648, which have
their opposite ends fixedly mounted in the moving portion 620 of
the auxiliary coil and which bolts 646, 648 further extend through
holes within moving portion 622.
An enlarged portion of FIG. 6 that is enclosed by the dot-dash
circle 700 is shown in more detail in FIG. 7. The rod 628 is
provided movably on the lever 616. The moving portion 622 is
movably supported in the rod 628 by means of an enlarged hole 710
therein and further is provided with two holes 712, 714 through
which the push bolts 648 and 646 respectively extend to where they
are secured to the moving portion 620. The other ends of the push
bolts 646, 648 are positioned through the holes of the plate 644,
respectively. Springs 716, 718 are respectively provided between
the plate 644 and the moving portion 622 surrounding the bolts so
as to move the plate independently of the upper ends of these bolts
646, 648. The plate 644 has the two bolts 640, 642 rigidly secured
thereto on which the sheet 636 is secured by scress formed on the
ends of the bolts 642, 640 and in the sheet 636. The coil spring
626 is provided between the stop 634 of the shaft 628 and the cross
piece 636.
FIG. 8 is a cross sectional view on line VII--VIII of FIG. 6. The
electromagnetic coil 632 has the moving portion 620 provided with
three holes 810, 812, 814 through which pass the bolt 628 and the
two push bolts 846 and 848. The lower ends of the push bolts 646,
648 are received and secured by the moving portion 620 adn the
upper ends of the push bolts 646, 648 are received and secured
within the moving portion 622 (not shown).
FIG. 9 is a cross sectional view taken along line IX--IX of FIG. 6.
The moving portion 620 is provided with two holes 814, 812 through
which the push bolts 846, 848 extend. The lower ends of the push
bolts 846, 848 are engaged with the cross piece 934 by the springs
916, 918. The two bolts 940, 942 are rigidly secured to the cross
piece 934 and have a cross piece 936 with two negative screw holes
cooperating with the screws of the holes 940, 942.
With reference to FIGS. 6, 7, 8, 9, when the coil 632 is energized,
the moving portions 620, 622 of the auxiliary coil 630 are
attracted to each other so that the push bolts 646, 648 fixed on
the moving portion 620 and the push bolts 846, 848 fixed on the
moving portion 622 are pushed toward the outside. This movement of
the push bolts will push the cross pieces 636, 936 and cause the
gaps G between the spring cross piece 636 and the lever 616 and
between the spring cross piece 936 and the lever 618 against the
force of the spring 626. If the electromagnetic coil 632 is
disconnected, that is deenergized, the force of the spring 626 will
be applied to the levers 616, 618 through the spring cross pieces
636, 936 so as to cause frictional engagment between the shoes 614
and the drum 612.
When the electrically operated road or escalator is driven so as to
be moving upwardly or in the ascent stage, the total weight of the
passengers will have a tendency to stop the escalator. Only the
magnetic coil 630 will be disconnected, in order to keep the value
of the deceleration of an emergency stop at a suitable value.
On the other hand, during downward running, the weight of the
passengers will have a tendency to keep the escalator moving in the
downward direction. Thus, both the main coil 630 and the auxiliary
coil 632 will be disconnected or deenergized for increasing the
friction between the shoes and the drum. As a result, the value of
the deceleration of the escalator for an emergency stop will be
independent of the running direction.
Each of the spring cross pieces 636, 936 has a projection which
engages each recess of the left ends of levers 616, 618 in order to
prevent a shifting of the mechanism.
A side view of the braking device as shown in FIGS. 6, 7, 8, 9 is
illustrated in FIG. 10. In FIG. 10, the motor 2 is provided with
the transmission 3. The levers 616, 618 (only one of which is
shown) will have the brake shoes 614 shown previously and will be
movably supported by means of member 1050, which acts as a fulcrum
for the levers. The mgnetic coils 632, 630 will operate to close
the levers and stop rotation of the drum 612.
A further embodiment of the present invention is shown in FIGS. 11
and 12, wherein the force of the spring 1124 is applied to levers
1116, 1118 having shoes 1114 to apply braking friction to the brake
drum 1112. The electromagnetic coil 1130 causes compression of the
spring 1124 and opens the levers 1116, 1118. Particularly, the push
bolts 1140 fixed on the moving portion 1120 and the push bolts 1142
fixed on the moving portion 1122 will push the levers 1116, 1118
outwardly away from each other upon movement of the moving portions
inwardly upon energization of the coil 1130. The levers are
pivotally supported on cross member 1150.
When the electromagnetic coil 1130 is disconnected, the force of
spring 1124 is applied to the levers 1116, 1118 for stopping of the
drum 1112. If it is needed to increase the braking force, the
auxiliary electromagnetic coil 1132 is also disconnected, so that
the forces of springs 1160, 1162 will be applied to the levers
1116, 1118 through the two push bolts 1146, 1148 to further
increase the braking force. When the coil 1132 is energized, the
two moving portions 1123, 1121 are attracted toward each other and
the bolts 1146 and 1148 will move against the bias of the spring
1160, 1162 so that gaps G will be formed between the bolt ends and
the right hand ends of the levers 1116, 1118.
With reference to FIG. 13, the motor 2 is connected to a voltage
supply through contacts B.sub.0 or C.sub.0 and D.sub.0. At first,
an escalator is inspected and the safety switch K.sub.1 is turned
on when there in no accident.
When a key switch K.sub.2 is turned on in addition, contacts
A.sub.1, A.sub.2 are switched on by energizing the coil A. The
energizing current is held by connection of the contact A.sub.1
even after the key switch K.sub.2 is opened.
If a switch K.sub.3 for the running direction is switched to the
"UP" side, the coil B will be energized for closing contacts
B.sub.0, B.sub.1, B.sub.3, B.sub.4, B.sub.5, B.sub.6, and for
opening contact B.sub.2. The closing of the contact B.sub.1 holds
the current for energizing the coil B after switch K.sub.3 is
turned off. The disconnection of the contact B.sub.2 will
disconnect a coil C from the voltage supply. If the switch K.sub.3
is switched to the "DN" side during the ascent running by a mistake
of the operator, the coil C cannot be energized.
When the contact B.sub.3 is closed, a timer relay TE is energized
for closing the contact TE.sub.1 ; this timer relay has a certain
delay time for thereafter disconnecting the contact TE.sub.1. If
the timer relay TE is disconnected from the voltage supply by
turning off or opening the contact B.sub.3, after a certain period
of time the contact TE.sub.1 is disconnected. The connection of the
contact B.sub.4 energizes a coil F which connects the contact
F.sub.1. Since the contact TE.sub.1 has been connected by
energizing the timer relay TE, the current into the coil F also
flows through the contacts TE.sub.1, F.sub.1. If the contact
B.sub.4 becomes disconnected, all current for the coil F flows
through the contacts TE.sub.1, F.sub.1 until the contact TE.sub.1
is disconnected. The operation of the contacts F.sub.1, F.sub.2 has
a delay time defined by the delay time relay TE. The coil H is
energized by a connection of the contact F.sub.2 and a contact
H.sub.1 for magnetic coil 18 of the auxiliary brake is thereby
connected for energization. As a result, the force of the spring
624 (1124) of FIG. 6 (11) cannot be applied on the levers 616
(1116), 618 (1118), and cannot work as a power for the brake.
A coil I having contacts J.sub.1, J.sub.2 is energized by a
connection of the contacts L.sub.1, B.sub.5, with the contact
L.sub.1 being switched on when the coil L is not energized, and the
contact B.sub.5 being switched on by energization of the coil B. A
coil 630 (1130) is energized by closing of the contact J.sub.2 and
the levers 616 (1116), 618 (1118) are expanded against the force of
the spring 624 (1124) so that gaps between the shoes 614 (1114) and
the drum 612 (1112) are created. The contact D.sub.0 is turned on
by energization of coil D due to the switching on of the contact
B.sub.6.
The electric power that is applied to the motor 2 is supplied
through contacts C.sub.0, B.sub.0, D.sub.0.
If an emergency occurs suddenly, the switch K.sub.1 is turned off.
The contacts A.sub.1, A.sub.2 will thereby be turned off by
denergization of the coil A. The contacts B.sub.0, B.sub.1,
B.sub.3, B.sub.4, B.sub.5, B.sub.6 will accordingly be turned off
by deenergization of the coil B. Thus, the coils J, D, will be
deenergized, and the contacts D.sub.0, J.sub.2 will be turned off.
The motor 2 will be disconnected from the power supply by opening
of the contacts B.sub.0, D.sub.0. The magnetic coil 630 (1130) will
also be disconnected from the power supply which comprises a
rectifier circuit 1350 having four diodes and a A.C. voltage
supply. The force of the spring 624 (1124) of FIG. 6 (11) will be
applied to the levers 616 (1116), 618 (1118) for braking of the
drum 612 (1112). The timer relay TE has a certain delayed time,
which is the period between the time when the time relay is
disconnected from the power supply by disconnecting the contact
B.sub.3 and the time when the contact TE.sub.1 of the timer relay
TE is turned off. Therefore, despite the fact that the contact
B.sub.4 is disconnected, since the contact TE.sub.1 is switched on
for certain periods determined by the delay time of the timer relay
TE, the coil F is energized for this period until the contact
TE.sub.1 is turned off. After the switch K.sub.1 under emergency
conditions is turned off, the coil H is energized for the certain
period of the timer relay and the switch H.sub.1 is kept closed for
this predetermined period of time. Thus, the coil 632 (1132) for
the auxiliary brake is energized for the predetermined period of
time as determined by the delay time after the switch K.sub.1 under
emergency conditions is turned off, so that for that predetermined
period of time of the timer relay TE, the auxiliary brake will not
work.
On the other hand, the coil J having the contact J.sub.2 is
disconnected from the power supply by turning off the contact
B.sub.5 at almost the same time as the emergency switch K.sub.1 is
turned off. Since the coil 630 (1130) of the main brake is
disconnected from the power supply at the same time, the main brake
works as soon as the switch K.sub.1 is turned off.
As explained above, in the case of ascent, the main brake is
engaged at first and after a predetermined period of time, the
auxiliary brake will be engaged. During ascent running, the weight
of the passengers will act in the direction against the running
direction, so that only the main brake will act as the brake force
for the escalator. When the movement of the escalator stops, the
weight of the passengers acts on the escalator, tending to cause a
movement of the escalator downward. It is desirable to then engage
the auxiliary brake in order to prevent such downward movement or
slipping of the escalator, after the escalator has been stopped by
the main brake. It is desirable that the delay time of the timer
relay TE be the same as the period that is needed to stop the
escalator. Referring to FIG. 6 or FIG. 11, when the emergency
switch K.sub.1 is turned off, the coil 630 (1130) is disconnected
first, and the force of the spring 624 is applied on the drum 612
through the levers 618, 616 and shoes 614. Thereafter, the coil 632
(1132) is disconnected from the power supply and the force of the
spring 626 (1160), 1162 is also applied on the drum 12 after the
drum 12 is stopped for preventing the slipping movement being
caused by the weight of the passengers after the escalator has
stopped.
Assuming that operation of the escalator is in the descent running
condition, that is with switches K.sub.1, K.sub.2 being turned on
and the switch K.sub.3 is turned toward the down side, the coil C
is energized and the contacts C.sub.0, C.sub.1, C.sub.3, C.sub.4,
C.sub.5 are turned on. The coils 630 (1130), 632 (1132) are
energized by switching on the contacts L.sub.2, H.sub.1,
respectively. The shoes 14 of FIG. 6 (11) will separate from the
surface of the drum 612 (1112).
If an emergency condition occurs, the emergency switch K.sub.1 is
turned off. The coil C is disconnected by opening of the contact
A.sub.2 and the contacts C.sub.3, C.sub.4, C.sub.5 are switched
off. The coils H, L become deenergized and the contacts H.sub.1,
J.sub.2 are disconnected, which in turn will deenergize the coils
630 (1130), 632 (1132) at the same time. The forces of the spring
624, 626 (1124, 1160, 1162) are simultaneously applied on the drum
612 (1112) for stopping the movement of the escalator through the
levers 616 (1116), 618 (1118) and the shoe 614 (1114).
When the escalator is in the descent running condition, the forces
of the springs 624, 626 (1124, 1160, 1162) are simultaneously
applied on the drum for stopping the movement of the escalator.
On the other hand when the escalator is in the ascent running
condition, the main braking means having the coil 630 (1130) and
the spring 624 (1124) will work at first for stopping the escalator
and then the auxiliary braking means having the coil 632 (1132) and
spring 626 (1160, 1162) will work for applying the force of the
springs on the drum 612 (1112) through the shoe 614 (1114) as a
braking force upon emergency conditions.
Since the operation of the various embodiments, with modifications
has been set forth during the description of the structure, further
details of the operation are unnecessary.
While various embodiments, modifications and variations have been
set forth in purposes of illustration and for the advantageous
details in their own right, further embodiments, modifications, and
variations are contemplated according to the broader aspects of the
present invention, all as determined by the spirit and scope of the
following claims.
* * * * *