Abstract:
The present invention relates to a low-speed brake apparatus for an escalator, comprising: a brake sprocket mounted on a drive shaft for a step; a driven sprocket connected to the brake sprocket through a brake chain to operate in conjunction with the brake sprocket; an electronic clutch that controls a connection between the driven sprocket and a transmission gear; a brake motor of which the central shaft is rotated by the transmission gear; a plurality of switching means connected to a plurality of winding wires that are stators of the brake motor; and a controller for supplying an operating pulse to a selected switching means. Therefore, when there is an abnormality in an escalator, it is possible to stop a step at a low speed according to an operating pulse supplied by the controller, thereby stably stopping riders standing on the step and thus protecting the riders.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a linear brake apparatus for an escalator and, more particularly, to a low-speed brake apparatus for an escalator in which the step and hand rail of the escalator are linearly braked optimally. 
     Discussion of the Related Art 
     As noted, an escalator is installed in buildings having a variety of types of structures. The escalator in which steps are installed on an endless track can move much many people than an elevator to an upper floor or a lower floor. The escalator has an open type structure to enable people thereon to see a view around. The escalator is widely installed on department stores, hotels, large shopping centers, and subway stations. 
     The structure of such an escalator is described below. A driving motor for generating a motive power for up and down driving steps connected to the endless track onto which a passenger steps and driving sprockets connected to the driving shaft of the driving motor are connected by a driving chain. Step sprockets rotated when the driving shaft is rotated by the motive power of the driving motor moves step chains, so the escalator operates to go up and down. 
     Such an escalator has a main brake included in the driving motor and is driven by a controller, if necessary. The escalator is suddenly braked when a safety accident, such as a get-between accident, occurs by stopping the rotational movement of the driving motor. 
     The driving sprockets on both sides of the steps for the step driving of the escalator are connected by the driving shaft. The driving chain inserted into a driving motor rotation shaft rotates the driving sprockets, thereby driving the steps. 
     Accordingly, when the driving chain connecting the driving motor and the sprockets of the driving shaft and transferring a motive power is broken, although the braking power of the main brake operates, the braking power cannot be transferred to the steps of the escalator. Accordingly, the steps of the escalator are suddenly accelerated while going down due to weight itself and weight of a passenger. The steps of the escalator are stopped while going up, instantly reversed, and accelerated to go down. Accordingly, there is a problem in that a serious injury accident is frequently generated because a passenger loses his or her balance due to inertia upon going up or down and falls down forward. 
     A representative example of such an escalator includes Korean Patent Application Publication No. 20-0466157 entitled “Disk hydraulic caliper type safety brake control apparatus for emergency stop of escalator for heavy load” (hereinafter referred to as a “cited invention”). 
     The cited invention relates to the disk hydraulic caliper type safety brake control apparatus for an emergency stop of escalator for a heavy load, as shown in  FIG. 1 , including step chains on which the steps of the escalator are installed, an escalator rotation shaft  30  equipped with driving sprockets  36  engaged with the respective step chains and adapted to move the step chains up or down while rotating forward or backward by a driving motor  21 , a counter rotation detection sensor which senses the rotation direction of the escalator rotation shaft  30 , an overspeed detection sensor which senses the rotation speed of the escalator rotation shaft  30 , an emergency stop safety brake  40  configured to block the rotation of the escalator rotation shaft  30  by a mechanical force, and a control unit configured to determine whether abnormality occurs in response to signals from the counter rotation detection sensor and the overspeed detection sensor and to control the emergency stop safety brake  40 . 
     The emergency stop safety brake  40  includes a disk brake  41  additionally installed on the escalator rotation shaft  30  and hydraulic calipers  42  configured to limit the rotation of the disk brake  41  by simultaneously applying pressure on both sides of the disk brake  41  and to operate in response to a signal from the control unit. 
     The emergency stop safety brake  40  is installed in accordance with the central portion of the escalator rotation shaft  30  so that the central portion of the escalator rotation shaft  30  can be braked. 
     The cited invention has a problem in that a serious safety accident may occur because passengers stepping onto the steps of the escalator fall down due to inertia if the escalator going down at a high speed is rapidly braked by a hydraulic caliper type emergency stop safety brake although the driving chain is broken. 
     SUMMARY OF THE INVENTION 
     In order to solve such problems, an object of the present invention is to propose a low-speed brake apparatus for an escalator, which can prevent an injury of a passenger attributable to sudden braking through smooth deceleration to the extent that the passenger stepping onto a step does not fall down if it is necessary to stop a movement of the step while the escalator operates. 
     In order to achieve the object, a low-speed brake apparatus for an escalator includes a brake sprocket installed on a driving shaft, wherein step sprockets engaged with step chains and a driving sprocket are respectively installed on both sides of the driving shaft and a driving chain inserted into the rotation shaft of a driving motor rotates the driving sprocket so that a step is driven, a follower sprocket connected to the brake sprocket by a brake chain in such a way as to operate in conjunction with the brake sprocket, an electronic clutch regulating connection between the follower sprocket and a transmission gear, a brake motor having a center shaft rotated by the transmission gear, a plurality of switching means connected to a plurality of windings, that is, the stator of the brake motor, and a controller for supplying an operation pulse to selected switching means. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing a conventional disk hydraulic caliper type emergency stop safety brake control apparatus of an escalator for a heavy load. 
         FIG. 2  is an explanatory diagram showing main elements of an escalator to which the present invention has been applied. 
         FIG. 3  is a schematic view of a low-speed brake apparatus for an escalator according to the present invention. 
         FIG. 4  is a waveform showing output pulses output by a controller according to the present invention. 
         FIG. 5  is an explanatory diagram showing an electronic clutch and a transmission gear which may be applied to the present invention. 
         FIG. 6  is an explanatory diagram showing the operating state of  FIG. 5 . 
         FIGS. 7 and 8  are circuit diagrams showing the configuration of switching means which may be applied to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     A low-speed brake apparatus for an escalator includes a brake sprocket installed on a driving shaft, wherein step sprockets engaged with step chains and a driving sprocket are respectively installed on both sides of the driving shaft and a driving chain inserted into the rotation shaft of a driving motor rotates the driving sprocket so that a step is driven, a follower sprocket connected to the brake sprocket by a brake chain in such a way as to operate in conjunction with the brake sprocket, an electronic clutch regulating connection between the follower sprocket and a transmission gear, a brake motor having a center shaft rotated by the transmission gear, a plurality of switching means connected to a plurality of windings, that is, the stator of the brake motor, and a controller for supplying an operation pulse to selected switching means. 
     Embodiments of the present invention are described in detail below with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains readily implement the present invention. 
     An overall configuration of an escalator to which a low-speed brake apparatus for an escalator according to the present invention has been applied is shown in  FIG. 2 . The elements of the escalator are schematically shown in  FIG. 3  in order that a motive power is transferred upon braking. 
     As may be seen from the following description, in the low-speed brake apparatus according to the present invention, two step sprockets  100  and a driving sprocket  102  engaged with step chains installed under a step (not shown) onto which a passenger steps are fixed on both sides of a driving shaft  101 , respectively. 
     Furthermore, a driving chain  103  inserted into the rotation shaft of a driving motor  104  rotates the driving sprocket  102  so that the step sprockets  100  fixed on the same axis are rotated, thereby driving the step. Accordingly, a brake sprocket  105  additionally installed on the driving shaft  101  is also rotated. The low-speed brake apparatus further includes a follower sprocket  201  connected to a brake chain  106  so that it operates in conjunction with the brake sprocket  105 , an electronic clutch  300  regulating connection between the follower sprocket  201  and a transmission gear  200 , a brake motor  400  rotated by the transmission gear  200 , a plurality of switching means connected to a plurality of windings, that is, the stator of the brake motor  400 , and a controller  500  for supplying an operation pulse to selected switching means so that a rotation load applied to the rotor  402  of the brake motor  400  is increased at a smooth speed. 
     As described above, in an escalator according to the present invention, in a normal operating state, the electronic clutch  300  does not operate under the control of the controller  500 . Accordingly, the brake sprocket  105  fixed to the driving shaft  101  and a rotation shaft  302  rotated by the brake chain  106  move to the left of  FIG. 2  by the elastic force of a return spring  305 , such as that shown in an enlarged portion “A” of  FIG. 2 . As shown in  FIG. 5 , a spline  303  stands by outside the boss  304  of a large gear  202 , and thus the rotating force of the rotation shaft  302  is not transferred to the large gear  202 . Accordingly, since the electronic clutch  300  does not yet operate, the rotation shaft  302  is separated from the transmission gear  200  and the center shaft  401  of the brake motor  400 , and thus the driving shaft  101  rotates in the state in which any braking has not applied to the driving shaft  101 . In this state, when the driving chain  103  is rotated by the motive power of the driving motor  104  and the driving chain  103  rotates the driving sprocket  102 , the driving shaft  101  rotates, the step sprockets  100  fixed to the driving shaft  101  rotate, and step chains (not shown) rotate. Accordingly, the step and a hand rail move at a stable speed in the direction in which the driving motor  104  rotates. As a result, a passenger who steps onto the step can move to an upper floor or a lower floor safely and conveniently. 
     In such a normal operation state, when an unexpected accident, such as the breakage or get-between detection of the driving chain  103 , is generated, the controller  500  drives the electronic clutch  300  to move the rotation shaft  302  to the right of  FIG. 6 , as shown in  FIG. 6 . Accordingly, the spline  303  of the rotation shaft  302  is coupled to a slit  307  formed in the boss  304  of the large gear  202 . As a result, a rotatory power transferred through the brake sprocket  105  fixed to the driving shaft  101  and the brake chain  106  changes the state so that the transmission gear  200  operates in conjunction with the center shaft  401  of the brake motor  400  through the electronic clutch  300 . 
     At this time, the controller  500  generates an output pulse for braking in order to stop the operation of the motor. As shown in  FIG. 4 , the output pulse is generated so that a duty rate t on /(t on +t off ), that is, a rate of an ON time t on  and OFF time t off , is gradually increased. 
     Such a duty ratio is output of the controller  500  implemented using a microprocessor, and may be set by a program. 
     As described above, as shown in  FIG. 4 , the duty ratio is small at the initial stage of braking and then gradually increased. Accordingly, if the output pulse maintains a high level when braking is completed, the switching means maintains a turn-on state and thus a maximum current flows into each of the windings of the brake motor  400 , thereby forming the strongest magnetic force. Accordingly, a permanent magnet, that is, the rotor  402 , becomes a state in which it is difficult to rotate. 
     In the present invention, for a switching implementation, an example in which Insulated Gate Bipolar Transistors (IGBT)  501  suitable for high power control have been used is illustrated in  FIGS. 7 and 8 . An example in which the IGBTs  501  have been used is described below, for convenience sake. 
     Accordingly, at the initial stage of braking having a small duty ratio, the amount of current that flows into surrounding windings due to the rotation of the rotor  402  of the brake motor  400  is small because the time when an electric current flows by the IGBTs  501  are short. Accordingly, a magnetic force generated from the fixed winding  403 , that is, a stator, is weak, and thus a braking power applied to the rotor  402  of the brake motor  400  is not great. In such an initial state, when braking is increased to a middle level, the duty ratio gradually increases, and thus the time when an electric current flows due to the IGBTs  501  is increased. Accordingly, the amount of current flowing into the surrounding fixed winding  403  is increased due to the rotation of the rotor  402  of the brake motor  400 , and thus a magnetic force generated from the fixed winding  403 , that is, the stator, becomes strong. As a result, a braking power is increased because it becomes difficult for the rotor  402  of the brake motor  400  to easily rotate. 
     When a set braking completion time is reached over time as described above, the electric current continues to flow by the IGBT  501 . Accordingly, the amount of current flowing into the surrounding winding becomes a maximum by the rotation of the rotor  402  of the brake motor  400 , and thus a magnetic force generated from the fixed winding  403 , that is, the stator, becomes the strongest. As a result, the braking power becomes a maximum because the rotation of the rotor  402  of the brake motor  400  is stopped. Accordingly, the transmission gear  200  connected to the rotor  402  of the brake motor  400 , the electronic clutch  300 , the brake chain  106 , the brake sprocket  105 , and the driving shaft  101  cannot be rotated. As a result, the step chains and the step rotated by the step sprockets  100  are stopped because the step sprockets  100  are not rotated. 
     Furthermore, in the present invention, the IGBT  501  has been illustrated as an example of high-power switching means, for convenience sake. However, a high-power transistor may be used as an example of the high-power switching means, and various other switching elements, such as a triac, may be used. 
     Furthermore, in the present invention, in order to smoothly control a flow of an electric current although the direction of an induced electromotive force induced by the fixed winding  403  is reversed depending on the rotation direction of the rotor  402 , PNP and NPN IGBTs  501  are connected in parallel. The controller  500  selectively applies output of a high level or low level to the gates of the IGBTs  501 . 
     As described above, in the present invention, the output pulse for braking is applied to the brake motor  400 , and a full braking state is reached after a set time elapses. Accordingly, the step is stopped at a smooth speed that has been safely optimized without the falling down of a passenger. 
     Furthermore, in the present invention, the electronic clutch  300  operates by output supplied by the controller  500  and transfers a braking power. If output is not supplied by the controller  500 , the electronic clutch  300  is separated from the transmission gear  200  and a braking power is never transferred. Accordingly, the driving shaft  101  normally operates and moves the step up or down. The structure of a representative electronic clutch  300  and transmission gear  200  which may be applied to the present invention is shown in  FIG. 5 . 
     As may be seen from  FIG. 5 , in the low-speed brake apparatus according to the present invention, the brake chain  106  connected and rotated by the brake sprocket  105  rotates the follower sprocket  201 . The follower sprocket  201  includes the electronic clutch  300  including the rotation shaft  302  equipped with the spline  303 , a clutch coil  301 , and the slit  307  formed in the boss  304  of the large gear  202  forming the transmission gear  200 , the transmission gear  200  including the large gear  202  and a pinion  203 , and the center shaft  401  of the brake motor  400  coupled to the pinion  203 . 
     In accordance with such an embodiment, the spline  303  has been illustrated as being formed in the rotation shaft  302  fixed to the center of the follower sprocket  201  rotated by the brake chain  106 . Such a spline  303  is connected to the follower sprocket  201  by the slit  307  formed in the boss  304  of the large gear  202  of the transmission gear  200 . 
     Accordingly, in the present invention, when an electric current supplied by the controller  500  flows into the clutch coil  301  of the electronic clutch  300 , the clutch coil  301  sucks the rotation shaft  302 , and thus the rotation shaft  302  of the follower sprocket  201  moves to the left of  FIG. 6 , as shown by an arrow of  FIG. 6 . 
     As a result, the rotatory power of the follower sprocket  201  rotated by the brake chain  106  is coupled to the slit  307  formed in the boss  304  of the large gear  202  to which the spline  303  is coupled, thereby rotating the pinion  203 . Accordingly, the center shaft  401  of the brake motor  400  is rotated and thus the rotor  402  starts to rotate thereby generating an induced electromotive force in the fixed winding  403  of the brake motor  400 . The induced electromotive force flows into the fixed winding  403  and is magnetized so that it has polarity opposite that of the rotor  402 , that is, a permanent magnet. As a result, the rotor  402  is sucked by the fixed winding  403 , thereby making the rotor  402  difficult to rotate. 
     Accordingly, the rotatory power supplied by the brake chain  106  reaches the brake motor  400  through the follower sprocket  201 , the large gear  202  of the transmission gear  200 , and the pinion  203 . However, the rotor  402  fixed on the same axis as the center shaft  401  of the pinion  203  becomes difficult to rotate by the fixed winding  403 , thereby making the brake chain  106  difficult to rotate. Accordingly, braking is applied to even the brake sprocket  105  and the driving shaft  101 . As a result, the rotation of the step sprockets  100  fixed on the same axis as the driving shaft  101  is braked to limit a movement of the step. 
     Accordingly, the braking power by the brake motor  400  is applied to the step onto which a passenger steps through such a process. More specifically, in the present invention, a braking power is smoothly increased during period from the time when an operation is started to the time when the operation is terminated by controlling a flow of the electric current of an induced electromotive force flowing into the fixed winding  403  of the brake motor  400 . Accordingly, a corresponding escalator is stopped at an optimum speed so that a passenger who has stepped on a step does not fall down. In the present invention, the electronic clutch  300  and the transmission gear  200  have been illustrated as examples in  FIGS. 5 and 6 , but various types of electronic clutches  300  and transmission gears  200  may be used in addition to the aforementioned structures. 
     Furthermore, in the present invention, an example in which three pairs of the windings of the brake motor  400  have been installed is illustrated. For example, a single IGBT  501  may be connected to three pairs of the windings in each of which two controllers  500  forms a pair. A phase angle detection sensor  502  for detecting an angle of the rotor  402  and selecting and controlling the IGBTs  501  connected to both ends of the fixed winding  403  in accordance with the detected angle of the rotor  402  has been installed. 
     Furthermore, in the present invention, the brake motor  400  may have a low-power generation capability in accordance with deceleration because it adopts an electrical braking method, and thus may have the possibility that a braking power is also reduced. In order to overcome such a problem, a brake caliper, such as that of cited invention, and known mechanical braking means using a disk brake may be used in combination with the brake motor  400  in order to further enhance safety. 
     Furthermore, in the present invention, an external power source VCC is applied to the fixed winding  403  of the brake motor  400  via a switching element as operation power. Accordingly, a strong braking power can be exerted from the initial braking stage to the braking completion stage by controlling the controller  500  so that torque is generated in an inverse direction to the rotation direction. In such a case, the mechanical braking means does not need to be accessorily used. Such an embodiment is shown in  FIG. 8 . 
     Furthermore, in the present invention, the rotatory power of the brake sprocket  105  has been illustrated as being transferred to the follower sprocket  201  using the brake chain  106 . For example, various motive power transfer means, such as a time belt, may be used instead of the brake chain  106 . 
     Furthermore, in the present invention, in order for the electronic clutch  300  to smoothly operate, a magnetism plate  308  may be installed on one side of the rotation shaft  302 . When the clutch coil  301  is magnetized by the magnetism plate  308 , the rotation shaft  302  immediately moves to the right of  FIG. 5 , thereby being capable of generating a rapid braking power. 
     Furthermore, in the present invention, since the follower sprocket  201  is rotated by the brake chain  106  and the large gear  202  is rotated by the follower sprocket  201 , the center shaft of the brake motor  400  engaged with the pinion  203  is rotated at a high speed, but torque is reduced in accordance with the increase of the rotation speed. Accordingly, the driving shaft  101  in addition to the follower sprocket  201  can be strongly braked by a small braking power. 
     As described above, in the present invention, the amount of current that flows per hour in the switching element can be controlled by an operation pulse supplied by the controller. A magnetic pole formed in the fixed winding controls a time width in which the rotation of the permanent magnet, that is, a rotor, is suppressed by adjusting the amount of current that flows into the fixed winding, that is, the stator of the brake motor. Accordingly, the rotation of the brake sprocket and the driving shaft fixed to the center of the brake sprocket can be suppressed and stopped at a smooth speed in response to an operation pulse supplied by the controller. Accordingly, there is an advantage in that human life can be protected because a passenger who steps onto a step can be safely stopped. 
     Furthermore, in the present invention, an optimum stop consumption time can be set in accordance with volumes, such as the number of passengers who boards an escalator and weight of steps, through control of the duty cycle of an operation pulse by only modifying a program installed on the controller. Accordingly, there are advantages in that an escalator can operate silently because it can be stopped safely and rapidly and there is no noise generated in a braking operation process. 
     As described above, the present invention is not limited to the aforementioned embodiments, but may be changed and implemented in various ways without departing from a gist and concept intended by the present invention.