CA1123362A - Escalator - Google Patents
EscalatorInfo
- Publication number
- CA1123362A CA1123362A CA336,520A CA336520A CA1123362A CA 1123362 A CA1123362 A CA 1123362A CA 336520 A CA336520 A CA 336520A CA 1123362 A CA1123362 A CA 1123362A
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- Canada
- Prior art keywords
- escalator
- inertia
- predetermined
- conveyor
- deceleration
- Prior art date
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Abstract
16 48,030 ABSTRACT OF THE DISCLOSURE
An escalator for transporting passengers between upper and lower landings. The escalator includes a fly-wheel and a failsafe brake, with the brake being applied when the escalator is to stop, regardless of load or travel direction. The inertia of the flywheel and the braking torque of the brake are predetermined to provide the de-sired range of deceleration, when the escalator stops in either travel direction, regardless of passenger load, between no-load and rated load.
An escalator for transporting passengers between upper and lower landings. The escalator includes a fly-wheel and a failsafe brake, with the brake being applied when the escalator is to stop, regardless of load or travel direction. The inertia of the flywheel and the braking torque of the brake are predetermined to provide the de-sired range of deceleration, when the escalator stops in either travel direction, regardless of passenger load, between no-load and rated load.
Description
33~
, ~
1 ~8,030 ESCALATOR
BACKGROUND OF THE INVE~TION
Field of the Invention:
The invention relates in general to escalators, and more specifically to arrangements for stopping an escalator.
Description of the Prior Art:
Rule 80~ of the ANSI A17.1-1978 Safety Code for Escalators states that "escalators should be provided with an electrically released, mechanically applied brake capa-ble of stopping an up or down traveling escalator with anyload up to brake design load".
The maximum braking effort is required to stop a fully loaded escalator going down~ and thus the brake is sized accordingly. For examp:le, the brake torque is selec-ted to provide some minimum value of deceleration, such as about 1 ft/sec2, when an escalator with rated load is stopped while transporting passengers from an upper landing to a lower landing. Thus, any o-ther condition than a fully loaded escalator going down will result in a higher rate of deceleration. The highest rate of deceleration would occur when a fully loaded escalator is braked -to a stop while transporting passengers from the lower landing to the upper 33~;~
,. ~
, ~
1 ~8,030 ESCALATOR
BACKGROUND OF THE INVE~TION
Field of the Invention:
The invention relates in general to escalators, and more specifically to arrangements for stopping an escalator.
Description of the Prior Art:
Rule 80~ of the ANSI A17.1-1978 Safety Code for Escalators states that "escalators should be provided with an electrically released, mechanically applied brake capa-ble of stopping an up or down traveling escalator with anyload up to brake design load".
The maximum braking effort is required to stop a fully loaded escalator going down~ and thus the brake is sized accordingly. For examp:le, the brake torque is selec-ted to provide some minimum value of deceleration, such as about 1 ft/sec2, when an escalator with rated load is stopped while transporting passengers from an upper landing to a lower landing. Thus, any o-ther condition than a fully loaded escalator going down will result in a higher rate of deceleration. The highest rate of deceleration would occur when a fully loaded escalator is braked -to a stop while transporting passengers from the lower landing to the upper 33~;~
,. ~
2 ~8,030 landing. rhis may be about 8 to 10 ft/sec2 for a typica~
escalator with a fixed braking torque.
The prior art has disclosed many different arrangements which adjust the brakin~ effort, in order ~o decrease the range between the minimum and maximum rates of deceleration which may occur, by taking such things as speed, load and/or travel direction into account. For example, the braking effort may be adjusted (a) according to the load, (b) according to speed, such as in response to an error signal which is responsive to the difference between the actual speed and the desired speed of the escalator while braking to a stop, or (c) in response to travel direction. In general, such controlled braking arrangements add substantially to the cost of an escalator, as well as to the maintenance thereof, because of the more complex mechanical and/or electrical apparatus required.
It would be desirable to provide a new and im-proved stopping arrangement for an escalator which enables an escalator to stop wit:hin a predetermined selected range of deceleration rates, without requiring the speed, load or travel direction to be sensed.
SUM~I~RY OF T~IE INVFNTION
Briefly, the present invention is a new and im-proved escalator which has a fail-safe, fixed torque brake, which will decelerate and stop an escalator within a prede-termined selected range of deceleration, which range ~ay be much smaller than prior art escalators equipped with a fixed torque brake. In accordance with the invention, the inertia of the escalator is increased, such as by adding a flywheel to the escalator drive mechanism, with the fly-llZ33~2
escalator with a fixed braking torque.
The prior art has disclosed many different arrangements which adjust the brakin~ effort, in order ~o decrease the range between the minimum and maximum rates of deceleration which may occur, by taking such things as speed, load and/or travel direction into account. For example, the braking effort may be adjusted (a) according to the load, (b) according to speed, such as in response to an error signal which is responsive to the difference between the actual speed and the desired speed of the escalator while braking to a stop, or (c) in response to travel direction. In general, such controlled braking arrangements add substantially to the cost of an escalator, as well as to the maintenance thereof, because of the more complex mechanical and/or electrical apparatus required.
It would be desirable to provide a new and im-proved stopping arrangement for an escalator which enables an escalator to stop wit:hin a predetermined selected range of deceleration rates, without requiring the speed, load or travel direction to be sensed.
SUM~I~RY OF T~IE INVFNTION
Briefly, the present invention is a new and im-proved escalator which has a fail-safe, fixed torque brake, which will decelerate and stop an escalator within a prede-termined selected range of deceleration, which range ~ay be much smaller than prior art escalators equipped with a fixed torque brake. In accordance with the invention, the inertia of the escalator is increased, such as by adding a flywheel to the escalator drive mechanism, with the fly-llZ33~2
3 48, 030 wheel being sized to prevent a ful:Ly loaded esc~llatortraveling in the up direction from stopping too cluickly.
This sets the upper limit to the range of deceleration.
The brake is sized to prevent a fully loaded escalator going down from exceeding a predetermined stopping distance This sets the lower limit to the range of deceleration.
Thus, a predetermined clesired range of deceleration is achieved by adding a flywheel of predetermined size, and selecting the brake to provide a predetermined braking torque. The desired range of deceleration is then achievèd automatically for any load and travel direction~ without requiring speed, load or travel direction to be sensed.
BRIEF DESCRIPTION OF THE DRAWINGS~
The invention may be better understood, and further advantages and uses thereof more readily apparent, when considered in view of the following de-tailed descrip-tion of exemplary embodiments~ taken with the accompanying drawings in which:
Figure 1 is an elevational view of an escalator 2n which may be constructed according to the teachi~gs of the invention;
Figure 2 is a plan view of a drive unit for an escalator constructed according to the teachings of the invention; and Figure 3 is a schematic diagram which illustrates a control circuit for the escalator of Figure 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, and to Figure 1 in particular, there is shown an escalator 10 of the type which may utilize the teachings of the invention. Escala-33~i2 , 0 3 0 tor lO employs a conveyor l2 Eor transpor~ing passengers, between a Eirst or lower landing 1~ and a second or upper landing 16. The conveyor 12 is of the endless type, having an upper load bearing run 18 on which passengers stand while being transported between the landings, and a lower return run 20.
A balustrade 22 is disposed above the conveyor 12 for guiding a continuous, flexible handrail 24. The balus-trade guides the handrail 24 as it moves about a closed loop which includes an upper run 26 during which a surface of a handrail 24 may be grasped by passengers as they are transported along the conveyor 12, and a lower return run 28. The handrail 24 is guided around the balustrade by suitable guide means, such as a T-shaped guide member which is located within the C-shaped cross-section of the hand-rail 24.
Conveyor 12 includes a plurality of steps 36, only a few of which are shown in Fig~ 1. The steps are each clamped to a step axle, and ~hey move in a closed path, with the conveyor 12 being Ariven in a conventional manller, such as illustrated :in U.S. Patent 3,414,109, or the conveyor 12 may be driven by a modular drive arrange-ment as disclosed in U.S. Patent 3,677,388, both of which are assigned to the same assignee as the present applica-tion. For purposes of example, the modular drive arrange-ment is shown in Fig. 1.
As disclosed in U.S. Patent 3,677,388, the con-veyor 12 includes an endless belt 30 having first and second sides, with each side being formed of toothed links 38, interconnected by the step axles to which the steps 36
This sets the upper limit to the range of deceleration.
The brake is sized to prevent a fully loaded escalator going down from exceeding a predetermined stopping distance This sets the lower limit to the range of deceleration.
Thus, a predetermined clesired range of deceleration is achieved by adding a flywheel of predetermined size, and selecting the brake to provide a predetermined braking torque. The desired range of deceleration is then achievèd automatically for any load and travel direction~ without requiring speed, load or travel direction to be sensed.
BRIEF DESCRIPTION OF THE DRAWINGS~
The invention may be better understood, and further advantages and uses thereof more readily apparent, when considered in view of the following de-tailed descrip-tion of exemplary embodiments~ taken with the accompanying drawings in which:
Figure 1 is an elevational view of an escalator 2n which may be constructed according to the teachi~gs of the invention;
Figure 2 is a plan view of a drive unit for an escalator constructed according to the teachings of the invention; and Figure 3 is a schematic diagram which illustrates a control circuit for the escalator of Figure 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, and to Figure 1 in particular, there is shown an escalator 10 of the type which may utilize the teachings of the invention. Escala-33~i2 , 0 3 0 tor lO employs a conveyor l2 Eor transpor~ing passengers, between a Eirst or lower landing 1~ and a second or upper landing 16. The conveyor 12 is of the endless type, having an upper load bearing run 18 on which passengers stand while being transported between the landings, and a lower return run 20.
A balustrade 22 is disposed above the conveyor 12 for guiding a continuous, flexible handrail 24. The balus-trade guides the handrail 24 as it moves about a closed loop which includes an upper run 26 during which a surface of a handrail 24 may be grasped by passengers as they are transported along the conveyor 12, and a lower return run 28. The handrail 24 is guided around the balustrade by suitable guide means, such as a T-shaped guide member which is located within the C-shaped cross-section of the hand-rail 24.
Conveyor 12 includes a plurality of steps 36, only a few of which are shown in Fig~ 1. The steps are each clamped to a step axle, and ~hey move in a closed path, with the conveyor 12 being Ariven in a conventional manller, such as illustrated :in U.S. Patent 3,414,109, or the conveyor 12 may be driven by a modular drive arrange-ment as disclosed in U.S. Patent 3,677,388, both of which are assigned to the same assignee as the present applica-tion. For purposes of example, the modular drive arrange-ment is shown in Fig. 1.
As disclosed in U.S. Patent 3,677,388, the con-veyor 12 includes an endless belt 30 having first and second sides, with each side being formed of toothed links 38, interconnected by the step axles to which the steps 36
4~,030 are connectecl. The steps 36 are supported by main and trailer rol]ers l~o and 42, respectively, at opposite sides of the endless belt 30. The main and trailer rollers ~0 and 42 cooperate with support and guide tracks 46 and 48, respectively, to guide the steps 36 in the endless path or loop.
The steps 36 are driven by a modular drive unit 52 which includes sprocket wheels, and a drive chain for engaging the tooth links 38. The modular drive unit 52 includes a handrail drive pulley 54 on each side of the -conveyor which drives the handrail unit 56.
Fig. 2 is a plan view of drive unit 52 shown in Fig. 1, with the drive unit 52 shown in ~ig. 2 being con-structed according to the teachings of the invention. In general, drive unit 52 includes a drive motor 60, such as a three-phase, 60 Hz. induction motor, a gear reducer 62, drive sprocke-t wheels 64 and 66~ and idler sprocket wheels 68 and 70. The gear reducer 62, which may be a commercial 36.2:1 gear reducer, has an input shaft 72 and an output shaft 74. The drive motor 60 has a motor shaft 76. The motor shaft 76 is coupled to the input shaft 72 o~ the gear reducer 62 by any suitable means, such as via pulleys 78 and 80, and a timing belt 82. A broken belt switch 84 monitors the integrity of belt 82.
The output shaft 74 of gear reducer 62 is con-nected to the drive sprockets 64 and 66, and each driven sprocket is coupled with an idler sprocket via a drive chain 86. As illustrated, the drive chain may have three strands, with the outer two s-trands engaging teeth on the sprocket, and with the inner strand engaging the teeth on 6 l~8,030 the toothe~l links 38, to drive the endless belt 30 about its guidecl loop. ~ fai:L-safe friction brake 9~, which is electrically released and mechan:ically applied, is mounted on input shaf~ 72 of the gear reducer 62. ~rake 90 rnay be of any suitable type, such as the caliper brake illustrate~
in the hereinbefore-mentioned U.S. Patent 3,677,388, or the plate type brake illustrated in Fig. 2. In the plate type, a first plate member 92 rotates with shaft 72, and a second plate member 94, which is non-rotatable, is pulled back away from the rotatable plate 92 electrically, against a pressure from a spring or permanent magnet. If the elec-trical power connected to the brake is disconnected, ~he brake sets due to the pressure from the spring or permanent magnet, and is thus "fail-safe".
While the fail-safe function and the controlled braking torque function are preferably provided by a single brake as described, it is to be unders-tood that these func-tions may be provided by two separate brakes. For example, an electrically applied brake may be used to provide the desired braking torque because of the ease in selecting the torque, and a separate fail-sa~e brake may be used to brake the escalator due to power failure.
As will be hereinafter explained, a flywheel 100 is added to the drive unit 52, with the flywheel 100 being preferably applied to that element of the drive having the greatest rotational speed. Since the stored energy or momentum provided by a flywheel increases with the square of the rotational speed, the size of the flywheel may be reduced to a minimum by applying it to a r~tational part having the highest rotational speed. Thus, if there is a ~i ~ 3 3 7 ~8,030 reduction in the pulley arrangement 78 and 80 between the drive motor 60 and the reducer 62 J the preferable location for the flywheel is that illustrated in Fig. 2, i.e., on the motor shaft 76. If there is no reduction in the pulley arrangement, i.e., the arrangement is 1:1, the flywheel may be applied to the input shaft 72 of the reducer 62. Or, the required inertia may be divided and applied to both the motor shaft 76 and to the reducer input shaft 72. While the flywheel 100 i5 indicated as being a separate compon-ent, the flywheel 100 may be designed as part of thè pulley78, the pulley 80~ or both.
The following relationship applies to the drive unit 52 and escalator arrangement shown in Figs. 1 and 2:
. (~educer ~atio x Brake Torque) + Pas~enger`~oad (1) deceleratlon =
Illertla of Escalator When the escalator is traveling in the upward direction, the passenger load is positive, making both terms in the numerator of relationship (1) positive, resulting in a large value of deceleration. When the escalator is moving in the downward direction, the passenger load is negative, but always smaller than the brake torque, in order that the brake be capable of holding a full load of passengers.
Since the two terms tend to cancel, they result in a re-duced level of deceleration.
From relationship (1), set forth aboveJ it is recognized that there are two variables that can be ad-justed to give a desired deceleration, the brake torque and inertia. It is further recognized that it is not necessary to provide the same rate of deceleration for any load in 33~;~
., 8 48,030 either travel direction, as a range of deceleration may be provided which is entirely acceptable for passenger comfort For purposes of example, it will be assumed that a desir-able range is between 1 and 4 ft/sec2. Calculat:ions will be presented for this range, and also for a range of 1 to 2 ft/sec2 .
Using the range of 1 to 4 ft/sec2 as an example, the greatest deceleration, 4 ft/sec2 will occur in the full load up direction, since the brake torque and passenger load have the same sign when traveling up. The minimum rate of deceleration, i.e., 1 ft/sec2, will occur at full load down, with all other loads in either direction result-ing in a deceleration rate between 1 and ~ ft/sec2.
There are two basic equations, one for full load up, and one for full load down, and two unknowns, the inertia and brake torque. Thus, it is possible to deter-mine the exact sizes of the brake and inertia that will satisfy the equations. Once calculated, these values identify the smallest values which may be used and still provide the predetermined selected range of deceleration.
If larger values of inertia are used, larger values of braking torque must also be used. The net effect is that the range of deceleration will be reduced. Thus, if a smaller desired range than 1 to ~ ft/sec2 is selected, such as 1 to 2 ft/sec2, the flywheel will have to be larger, and so will the braking torque.
The inertia of the typical prior art escalator is too small to provide the required amount of inertia to pre-vent a fully loaded stairway going up from stopping too quickly, i.e., higher than the selected upper limit of ` ~
33S~iZ
9 ~18, 030 ft/sec2, and it may typically be about ~ to 10 ft/sec2..
Thus, adding a predetermined amo-unt of inertia to the escalator system is a first s-tep in the present invention.
With inertia added to the system, according to the teach-ings of the invention, the brake of the typical prior art escalator will then be too small to prevent a fully loaded escalator traveling in the down direction from exceeding a predetermined desired ma~imum stopping dis-tance. Thus, increasing the size or torque rating of the brake, and the amount of the increase, are also part of the present inven-tion. As hereinbefore stated, the brake may be the same type of on-off, fail-safe friction brake commonly used on escalators. However~ its torque rating will be higher than on the typical prior art escalator, typically 50% higher than the average rating.
Tne required flywheel size may be determined for a predetermined escalator from the following relationships:
(2) Required Inertia = 2 x Raded Passenger Load eslre ece eratlon Range (3) Flywheel Inertia = Required Inertia - Actual Inertia In relationship (2), the deceleration range is determined by subtracting the minimum desired deceleration from the maximum desired deceleration.
The required brake torque is ~etermined for a predetermined escalator from the following relationship:
(4) Brake Torque =
Rated Load x (Max. Deceleration + Min. Deceleration) Ratio of Speed Reducer x (Max. Deceleration - Min Deceleration~
Using these relationships, the required flywheel size and brake size have been calculated for typical 32 and 48 inch wide modular drive escalators, with a 20 foot rise.
33~iZ
o 48 ~ 030 The flywheel and brake sizes have been calculated for a deceleration range of 1 to 4 Et/sec2, and also for a range of 1 to 2 ft/sec . The calculated 1ywheel and brake sizes are illustrated in Table I below.
TABLE I
Escalator Speed Flywheel ~ ft2) Brake (FPM) Applied to Motor Shaft (ft #) Dec. Rang~ ~ - ft/sec Dec. Rangi ~ _ ft/sec2 1 to 41 to 2 1 to 4 1 to 2 10 32" Width 10.8 35.2 77 142 120 18.6 62.4 77 142 90/120 42.5 142.0 77 142 48" Width 16.3 53 115 214 120 29 93 115 ` 214 While the escalator brake is a fixed brake, i.e., it is not adjustable, the braking torque may not be con-stant throughout the speed range as an escalator is brakedto a stop. The particular brake torque versus speed rela-tionship will depend upon the specific brake selected. In determining the flywheel size in Table I, an average brak-ing torque is assumed. I the braking torque o the par-ticular brake selected does not increase`appreciably at the lower RP~I of the drive motor, the calculated size of the flywheel may be used without change. However, if a brake is used which does significantly increase the braking torque at the lower rpm, the flywheel size will have to be larger than calculated in order to prevent the maximum deceleration from being exceeded.
Practical experience has shown that some varia-3 3 ~ Z
~ 8,030 tion in sys~em con~ponents is to be expected. The brake torque, gearing efficiency, drag, etc., can all contribute to this variation. Thus, it is preferable to specify a brake which is about 10% larger than the calculations indicate, with some acljustment means on the brake to pro-ide, for example~ a plus zero minus 20% torque range.
Then, by running the escalator unloaded, the exact brake torque for each escalator may be obtained by adjusting the brake torque until the desired stopping distance is ob-lo tained. This adjustment will then guarantee the desireddeceleration range regardless of load or travel direction.
~ ig. 3 is a schematic diagram which illustrates a control arrangement which may be used. A safety relay SFR
is connected between conductors 102 and 104, which are connected to a source of electrical potential via a string of safety contacts, shown generally as safety circuits 106.
The safety circuits may include contacts from the broken belt switch 84, switches responsive to broken step links 38, skirt safety switches, step up-thrust switches, broken drive chain switches, under/overspeed switch, maintenance switches, and the like.
If the safety circuits 106 indicate there is no malfunction in the system, relay SFR is energized and it closes a contact SFR-l in the circuit of a control relay CR. A start pushbutton 108 completes a series circuit between conductors 102 and 104 which also includes the coil of the control relay CR, and n.o. contact SFR-l of safety relay SFR. A seal-in contact CR-l of relay CR and a stop pushbutton 110 are serially connec-ted across the start pushbutton 10~.
~`~
33~Z
2 48, 030 The drive motor 60 is connected to a source 112 of electrical poten~ial via a contactor lll~ which includes an operating coil 116. The operating coil 116 is connected between conductors 102 and 104 via a normally open contact CR-2 of the control relay CR.
The brake coil BK of brake 90 is connected be-tween conductors 102 and 104 via a normally open contact CR-3 of control relay CR, and the safety circuits 106.
Thus, if the safety circuits are all closed, the safety relay SFR will be energized and its normally open contact SFR-l will be closed. Actuation o the start pushbutton 108 will then cause control relay CR to pick up and seal in via its contact CR-l. Contact CR-2 of the control relay CR
will also close to pick up contactor 114 to energize the drive motor, and contact CR-3 of the control relay CR will close to energize the brake coil BK and disengage the brake.
If the stop pushbutton 110 is depressed, relay CR
will drop and its contacts CR-2 and CR-3 will open to de-energize the drive motor 60 ancl engage the brake ~0. Thesame result will occur i~ any contact of the safety circuit 106 opens, as relay SFR will drop to open its contact SFR-l and drop the safety relay CR.
The steps 36 are driven by a modular drive unit 52 which includes sprocket wheels, and a drive chain for engaging the tooth links 38. The modular drive unit 52 includes a handrail drive pulley 54 on each side of the -conveyor which drives the handrail unit 56.
Fig. 2 is a plan view of drive unit 52 shown in Fig. 1, with the drive unit 52 shown in ~ig. 2 being con-structed according to the teachings of the invention. In general, drive unit 52 includes a drive motor 60, such as a three-phase, 60 Hz. induction motor, a gear reducer 62, drive sprocke-t wheels 64 and 66~ and idler sprocket wheels 68 and 70. The gear reducer 62, which may be a commercial 36.2:1 gear reducer, has an input shaft 72 and an output shaft 74. The drive motor 60 has a motor shaft 76. The motor shaft 76 is coupled to the input shaft 72 o~ the gear reducer 62 by any suitable means, such as via pulleys 78 and 80, and a timing belt 82. A broken belt switch 84 monitors the integrity of belt 82.
The output shaft 74 of gear reducer 62 is con-nected to the drive sprockets 64 and 66, and each driven sprocket is coupled with an idler sprocket via a drive chain 86. As illustrated, the drive chain may have three strands, with the outer two s-trands engaging teeth on the sprocket, and with the inner strand engaging the teeth on 6 l~8,030 the toothe~l links 38, to drive the endless belt 30 about its guidecl loop. ~ fai:L-safe friction brake 9~, which is electrically released and mechan:ically applied, is mounted on input shaf~ 72 of the gear reducer 62. ~rake 90 rnay be of any suitable type, such as the caliper brake illustrate~
in the hereinbefore-mentioned U.S. Patent 3,677,388, or the plate type brake illustrated in Fig. 2. In the plate type, a first plate member 92 rotates with shaft 72, and a second plate member 94, which is non-rotatable, is pulled back away from the rotatable plate 92 electrically, against a pressure from a spring or permanent magnet. If the elec-trical power connected to the brake is disconnected, ~he brake sets due to the pressure from the spring or permanent magnet, and is thus "fail-safe".
While the fail-safe function and the controlled braking torque function are preferably provided by a single brake as described, it is to be unders-tood that these func-tions may be provided by two separate brakes. For example, an electrically applied brake may be used to provide the desired braking torque because of the ease in selecting the torque, and a separate fail-sa~e brake may be used to brake the escalator due to power failure.
As will be hereinafter explained, a flywheel 100 is added to the drive unit 52, with the flywheel 100 being preferably applied to that element of the drive having the greatest rotational speed. Since the stored energy or momentum provided by a flywheel increases with the square of the rotational speed, the size of the flywheel may be reduced to a minimum by applying it to a r~tational part having the highest rotational speed. Thus, if there is a ~i ~ 3 3 7 ~8,030 reduction in the pulley arrangement 78 and 80 between the drive motor 60 and the reducer 62 J the preferable location for the flywheel is that illustrated in Fig. 2, i.e., on the motor shaft 76. If there is no reduction in the pulley arrangement, i.e., the arrangement is 1:1, the flywheel may be applied to the input shaft 72 of the reducer 62. Or, the required inertia may be divided and applied to both the motor shaft 76 and to the reducer input shaft 72. While the flywheel 100 i5 indicated as being a separate compon-ent, the flywheel 100 may be designed as part of thè pulley78, the pulley 80~ or both.
The following relationship applies to the drive unit 52 and escalator arrangement shown in Figs. 1 and 2:
. (~educer ~atio x Brake Torque) + Pas~enger`~oad (1) deceleratlon =
Illertla of Escalator When the escalator is traveling in the upward direction, the passenger load is positive, making both terms in the numerator of relationship (1) positive, resulting in a large value of deceleration. When the escalator is moving in the downward direction, the passenger load is negative, but always smaller than the brake torque, in order that the brake be capable of holding a full load of passengers.
Since the two terms tend to cancel, they result in a re-duced level of deceleration.
From relationship (1), set forth aboveJ it is recognized that there are two variables that can be ad-justed to give a desired deceleration, the brake torque and inertia. It is further recognized that it is not necessary to provide the same rate of deceleration for any load in 33~;~
., 8 48,030 either travel direction, as a range of deceleration may be provided which is entirely acceptable for passenger comfort For purposes of example, it will be assumed that a desir-able range is between 1 and 4 ft/sec2. Calculat:ions will be presented for this range, and also for a range of 1 to 2 ft/sec2 .
Using the range of 1 to 4 ft/sec2 as an example, the greatest deceleration, 4 ft/sec2 will occur in the full load up direction, since the brake torque and passenger load have the same sign when traveling up. The minimum rate of deceleration, i.e., 1 ft/sec2, will occur at full load down, with all other loads in either direction result-ing in a deceleration rate between 1 and ~ ft/sec2.
There are two basic equations, one for full load up, and one for full load down, and two unknowns, the inertia and brake torque. Thus, it is possible to deter-mine the exact sizes of the brake and inertia that will satisfy the equations. Once calculated, these values identify the smallest values which may be used and still provide the predetermined selected range of deceleration.
If larger values of inertia are used, larger values of braking torque must also be used. The net effect is that the range of deceleration will be reduced. Thus, if a smaller desired range than 1 to ~ ft/sec2 is selected, such as 1 to 2 ft/sec2, the flywheel will have to be larger, and so will the braking torque.
The inertia of the typical prior art escalator is too small to provide the required amount of inertia to pre-vent a fully loaded stairway going up from stopping too quickly, i.e., higher than the selected upper limit of ` ~
33S~iZ
9 ~18, 030 ft/sec2, and it may typically be about ~ to 10 ft/sec2..
Thus, adding a predetermined amo-unt of inertia to the escalator system is a first s-tep in the present invention.
With inertia added to the system, according to the teach-ings of the invention, the brake of the typical prior art escalator will then be too small to prevent a fully loaded escalator traveling in the down direction from exceeding a predetermined desired ma~imum stopping dis-tance. Thus, increasing the size or torque rating of the brake, and the amount of the increase, are also part of the present inven-tion. As hereinbefore stated, the brake may be the same type of on-off, fail-safe friction brake commonly used on escalators. However~ its torque rating will be higher than on the typical prior art escalator, typically 50% higher than the average rating.
Tne required flywheel size may be determined for a predetermined escalator from the following relationships:
(2) Required Inertia = 2 x Raded Passenger Load eslre ece eratlon Range (3) Flywheel Inertia = Required Inertia - Actual Inertia In relationship (2), the deceleration range is determined by subtracting the minimum desired deceleration from the maximum desired deceleration.
The required brake torque is ~etermined for a predetermined escalator from the following relationship:
(4) Brake Torque =
Rated Load x (Max. Deceleration + Min. Deceleration) Ratio of Speed Reducer x (Max. Deceleration - Min Deceleration~
Using these relationships, the required flywheel size and brake size have been calculated for typical 32 and 48 inch wide modular drive escalators, with a 20 foot rise.
33~iZ
o 48 ~ 030 The flywheel and brake sizes have been calculated for a deceleration range of 1 to 4 Et/sec2, and also for a range of 1 to 2 ft/sec . The calculated 1ywheel and brake sizes are illustrated in Table I below.
TABLE I
Escalator Speed Flywheel ~ ft2) Brake (FPM) Applied to Motor Shaft (ft #) Dec. Rang~ ~ - ft/sec Dec. Rangi ~ _ ft/sec2 1 to 41 to 2 1 to 4 1 to 2 10 32" Width 10.8 35.2 77 142 120 18.6 62.4 77 142 90/120 42.5 142.0 77 142 48" Width 16.3 53 115 214 120 29 93 115 ` 214 While the escalator brake is a fixed brake, i.e., it is not adjustable, the braking torque may not be con-stant throughout the speed range as an escalator is brakedto a stop. The particular brake torque versus speed rela-tionship will depend upon the specific brake selected. In determining the flywheel size in Table I, an average brak-ing torque is assumed. I the braking torque o the par-ticular brake selected does not increase`appreciably at the lower RP~I of the drive motor, the calculated size of the flywheel may be used without change. However, if a brake is used which does significantly increase the braking torque at the lower rpm, the flywheel size will have to be larger than calculated in order to prevent the maximum deceleration from being exceeded.
Practical experience has shown that some varia-3 3 ~ Z
~ 8,030 tion in sys~em con~ponents is to be expected. The brake torque, gearing efficiency, drag, etc., can all contribute to this variation. Thus, it is preferable to specify a brake which is about 10% larger than the calculations indicate, with some acljustment means on the brake to pro-ide, for example~ a plus zero minus 20% torque range.
Then, by running the escalator unloaded, the exact brake torque for each escalator may be obtained by adjusting the brake torque until the desired stopping distance is ob-lo tained. This adjustment will then guarantee the desireddeceleration range regardless of load or travel direction.
~ ig. 3 is a schematic diagram which illustrates a control arrangement which may be used. A safety relay SFR
is connected between conductors 102 and 104, which are connected to a source of electrical potential via a string of safety contacts, shown generally as safety circuits 106.
The safety circuits may include contacts from the broken belt switch 84, switches responsive to broken step links 38, skirt safety switches, step up-thrust switches, broken drive chain switches, under/overspeed switch, maintenance switches, and the like.
If the safety circuits 106 indicate there is no malfunction in the system, relay SFR is energized and it closes a contact SFR-l in the circuit of a control relay CR. A start pushbutton 108 completes a series circuit between conductors 102 and 104 which also includes the coil of the control relay CR, and n.o. contact SFR-l of safety relay SFR. A seal-in contact CR-l of relay CR and a stop pushbutton 110 are serially connec-ted across the start pushbutton 10~.
~`~
33~Z
2 48, 030 The drive motor 60 is connected to a source 112 of electrical poten~ial via a contactor lll~ which includes an operating coil 116. The operating coil 116 is connected between conductors 102 and 104 via a normally open contact CR-2 of the control relay CR.
The brake coil BK of brake 90 is connected be-tween conductors 102 and 104 via a normally open contact CR-3 of control relay CR, and the safety circuits 106.
Thus, if the safety circuits are all closed, the safety relay SFR will be energized and its normally open contact SFR-l will be closed. Actuation o the start pushbutton 108 will then cause control relay CR to pick up and seal in via its contact CR-l. Contact CR-2 of the control relay CR
will also close to pick up contactor 114 to energize the drive motor, and contact CR-3 of the control relay CR will close to energize the brake coil BK and disengage the brake.
If the stop pushbutton 110 is depressed, relay CR
will drop and its contacts CR-2 and CR-3 will open to de-energize the drive motor 60 ancl engage the brake ~0. Thesame result will occur i~ any contact of the safety circuit 106 opens, as relay SFR will drop to open its contact SFR-l and drop the safety relay CR.
Claims (7)
1. An escalator for transporting up to a pre-determined full load of passengers, at a predetermined rated speed, in a selectable travel direction, between spaced upper and lower landings, comprising:
a conveyor;
drive means for moving said conveyor at the pre-determined speed;
means for selectively energizing and deenergizing said drive means;
braking means for applying a predetermined brak-ing force to said conveyor, regardless of travel direction, when said drive means is deenergized;
and inertia means adding a predetermined value of inertia to said moving conveyor;
said predetermined value of inertia and said pre-determined braking force being selected to provide a decel-eration, when said drive means is deenergized and said braking means applies said predetermined braking force to said conveyor, which is within predetermined upper and lower limits, with the predetermined upper limit being the maximum desired deceleration when the conveyor is trans-porting the predetermined. full load of passengers from the 14 48,030 lower to the upper landing, and with the predetermined.
lower limit being the minimum desired deceleration when the conveyor is transporting the predetermined full load of passengers from the upper to the lower landing.
a conveyor;
drive means for moving said conveyor at the pre-determined speed;
means for selectively energizing and deenergizing said drive means;
braking means for applying a predetermined brak-ing force to said conveyor, regardless of travel direction, when said drive means is deenergized;
and inertia means adding a predetermined value of inertia to said moving conveyor;
said predetermined value of inertia and said pre-determined braking force being selected to provide a decel-eration, when said drive means is deenergized and said braking means applies said predetermined braking force to said conveyor, which is within predetermined upper and lower limits, with the predetermined upper limit being the maximum desired deceleration when the conveyor is trans-porting the predetermined. full load of passengers from the 14 48,030 lower to the upper landing, and with the predetermined.
lower limit being the minimum desired deceleration when the conveyor is transporting the predetermined full load of passengers from the upper to the lower landing.
2. The escalator of claim 1 wherein the drive means includes a drive motor having a motor shaft and a speed reducer having input and output shafts, with the motor shaft of said drive motor being coupled to the input shaft of said speed reducer, and with the output shaft of said speed reducer being coupled to the conveyor.
3. The escalator of claim 2 wherein the inertia means is coupled to the motor shaft.
4. The escalator of claim 2 wherein the braking means applies the predetermined braking force to the input shaft of the speed reducer.
5. The escalator of claim 2 wherein the inertia means is coupled to the motor shaft, and wherein the brak-ing means applies the predetermined braking force to the input shaft of the speed reducer.
6. The escalator of claim 1 wherein the required inertia for the escalator is equal to about twice the rated load divided by the deceleration range, and wherein the size of the inertia which is added to the escalator is equal to the difference between the required inertia and the actual inertia of the escalator before the inertia means is added.
7. The escalator of claim 1 wherein the predeter-mined braking force required is equal to about the rated load times the sum of the minimum and maximum deceleration rates of the desired range, divided by the ratio of the 48,030 speed reducer times the deceleration range.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US94936978A | 1978-10-06 | 1978-10-06 | |
| US949,369 | 1978-10-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1123362A true CA1123362A (en) | 1982-05-11 |
Family
ID=25488989
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA336,520A Expired CA1123362A (en) | 1978-10-06 | 1979-09-27 | Escalator |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS5856714B2 (en) |
| BR (1) | BR7906350A (en) |
| CA (1) | CA1123362A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4580675A (en) * | 1983-09-15 | 1986-04-08 | Westinghouse Electric Corp. | Transportation apparatus |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP7118261B2 (en) * | 2019-05-17 | 2022-08-15 | 三菱電機株式会社 | PASSENGER CONVEYOR BRAKE STATIC TORQUE MEASURING DEVICE AND PASSENGER CONVEYOR BRAKE STATIC TORQUE METHOD |
-
1979
- 1979-09-27 CA CA336,520A patent/CA1123362A/en not_active Expired
- 1979-10-03 BR BR7906350A patent/BR7906350A/en unknown
- 1979-10-05 JP JP12807079A patent/JPS5856714B2/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4580675A (en) * | 1983-09-15 | 1986-04-08 | Westinghouse Electric Corp. | Transportation apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5561589A (en) | 1980-05-09 |
| JPS5856714B2 (en) | 1983-12-16 |
| BR7906350A (en) | 1980-06-17 |
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| MKEX | Expiry |