Patent Application
20230312306
This application claims priority to Chinese Patent Application No. 202210228155.5, filed Mar. 8, 2022, and all the benefits accruing therefrom under 35 U.S.C. §119, the contents of which in its entirety are herein incorporated by reference.
The present application relates to elevator technology, in particular to a safety chain device and a safety protection system for an escalator.
A controller of an escalator is usually connected to a safety chain box through a long signal transmission cable (e.g., over 20 meters). The safety chain box includes a safety chain and a passive resistive network. When on-off states of protective switches forming the safety chain change, the equivalent resistance of the resistive network connected with the safety chain also changes. As a result, the controller can determine the protective switch whose state has changed by sampling the voltage associated with the equivalent resistance, and thus locate a drive chain that has failed. However, a problem that has plagued the industry for a long time is that the signal transmission cable connecting the controller and the safety chain box introduces noise into the transmission signal. When the signal transmission cable is long, a large noise component will cause a wrong safety detection signal to be received at the controller side, leading to misoperation. In addition, the equivalent resistance of the passive resistive network is non-linear, which further increases the difficulty of locating the protective switch whose state has changed.
According to an aspect of the present application, there is provided a safety chain device for an escalator, comprising: a safety chain including a plurality of protective switches connected in series, each of the protective switches is configured to switch from a first state to a second state in the event of abnormal operation of a respective corresponding drive chain; a resistive network encoder coupled with the safety chain and having a plurality of encoder output values, each of the encoder output values corresponds to one of the combinations of states of the plurality of protective switches; a processor coupled with the resistive network encoder and configured to output a level signal corresponding to the encoder output values; a first controlled current source coupled with the safety chain and configured to output a first current corresponding to a current flowing through the safety chain; and a second controlled current source coupled with the processor and configured to output a second current corresponding to the level signal.
Optionally, in the above safety chain device, the first state and the second state are a closed state and an open state respectively.
In addition to one or more of the above features, in the above safety chain device, both ends of the safety chain are coupled to a power supply and an input end of the first controlled current source respectively.
In addition to one or more of the above features, in the above safety chain device, the resistive network encoder comprises a plurality of paired input ends, and each of the paired input ends is coupled to both ends of one of the plurality of protective switches.
In addition to one or more of the above features, in the above safety chain device, the first controlled current source and the second controlled current source are current-controlled current sources.
Optionally, in the above safety chain device, the first controlled current source is configured to output a current k times the current flowing through the safety chain when the plurality of protective switches are all in the closed state and to output a zero current when at least one of the plurality of protective switches is in the open state.
Optionally, in the above safety chain device, output ends of the first controlled current source and the second controlled current source are coupled with an external device via a signal transmission cable.
In addition to one or more of the above features, in the above safety chain device, the processor is configured to analyze the states of the protective switches in real time.
According to another aspect of the present application, there is provided a safety protection system for an escalator, comprising: a safety chain device comprising: a safety chain including a plurality of protective switches coupled in series, each of the protective switches is configured to switch from a first state to a second state in the event of abnormal operation of a respective corresponding drive chain; a resistive network encoder having a plurality of encoder output values, each of the encoder output values corresponds to one of combinations of states of the plurality of protective switches; a processor coupled with the resistive network encoder and configured to output a level signal corresponding to the encoder output values; a first controlled current source coupled with the safety chain and configured to output a first current corresponding to a current flowing through the safety chain; and a second controlled current source coupled with the processor and configured to output a second current corresponding to the level signal; a control unit coupled with the first controlled current source and the second controlled current source and configured to perform corresponding safety protection operations in response to the first current and the second current.
Optionally, in the above safety protection system, the control unit comprises: a safety triggering mechanism coupled with an output end of the first controlled current source and configured to cut off a power supply from a main power supply to the escalator in response to a current output by the first controlled current source when at least one of the plurality of protective switches is in an open state; a microcontroller coupled with an output end of the second controlled current source.
Optionally, in the above safety protection system, the safety protection system further comprises a signal transmission cable, the output end of the first controlled current source and the output end of the second controlled current source are coupled with the safety triggering mechanism and the microcontroller, respectively, via the signal transmission cable.
Optionally, in the above safety protection system, the control unit further comprises an analog-to-digital converter coupled with the output end of the second controlled current source via the signal transmission cable, the analog-to-digital converter is configured to convert an analog voltage signal corresponding to the second current into a digital signal and output the digital signal to the microcontroller.
Optionally, in the above safety protection system, the safety triggering mechanism is a relay.
The above and/or other aspects and advantages of the present application will be more clearly and easily understood from the following description of various aspects in conjunction with the accompanying drawings, in which the same or similar elements are designated by the same reference numerals. The accompanying drawings include:
The present application is described more fully below with reference to the accompanying drawings, in which illustrative embodiments of the application are illustrated. However, the present application may be implemented in different forms and should not be construed as limited to the embodiments presented herein. The presented embodiments are intended to make the disclosure herein comprehensive and complete, so as to more comprehensively convey the protection scope of the application to those skilled in the art.
In this specification, terms such as “comprising” and “including” mean that in addition to units and steps that are directly and clearly stated in the specification and claims, the technical solution of the application does not exclude the presence of other units and steps that are not directly and clearly stated in the specification and claims.
Unless otherwise specified, terms such as “first” and “second” do not indicate the order of the units in terms of time, space, size, etc., but are merely used to distinguish the units.
A safety protection system 10 shown in
The safety chain device 110 includes a safety chain 111 composed of protective switches S1-Sn connected in series with each other. Each protective switch is associated with one of a plurality of drive chains and is in a normally closed state to form a current loop. When the drive chain is broken, the corresponding protective switch will be switched from a closed state to an open state, so that no more current will pass through the safety chain 111. As shown in
Continuing with
As shown in
Continuing with
In addition, the equivalent resistance of the above passive resistive network is non-linear, which makes it difficult for the microcontroller 123 to determine the position of the protective switch in the open state in the safety chain 111 for certain resistance points.
Further, in the above safety protection system, the number of the protective switches that can be detected is limited by the resolution of the analog-to-digital converter and the non-linear characteristics of the equivalent resistance, making it difficult to expand as needed.
For each of the plurality of protective switches, it can be in a closed state or an open state, so there are multiple combinations of states for the plurality of protective switches (e.g., n protective switches have 2n combinations of states). In some embodiments of the present application, the resistive network encoder coupled with the safety chain is utilized to detect the multiple combinations of states of the protective switches. In particular, the resistive network encoder has a plurality of encoder output values, and each encoder output value corresponds to one of the combinations of states. A correspondence of the output values to the combinations of states can be used to determine the position of the protective switch in the open state in the safety chain. Optionally, the encoder output values are processed by the processor and output in the form of digital signal.
In some embodiments of the present application, a controlled current source (e.g., a current-controlled current source or a voltage-controlled current source) is utilized to suppress or eliminate noise introduced by the signal transmission cable. In one example, the anti-interference capability of the signal is improved by adding a controlled current source between the output end of the safety chain and the signal transmission cable. In another example, the anti-interference capability of the signal is improved by adding a controlled current source between the output end of the processor and the signal transmission cable.
A safety protection system 20 shown in
Referring to
The safety chain 211 includes protective switches S1-Sn connected in series with each other, one end of which is connected to a power supply Vcc and the other end of which is grounded and connected to an input end of the first controlled current source 214 via a resistor Rs. Each protective switch is in a closed state when the associated drive chain is working normally, a constant current is is flowing from the safety chain 211 to the first controlled current source 214 at this time. On the other hand, when the drive chain is abnormal, the corresponding protective switch is switched from a closed state to an open state, and no more current flows to the first controlled current source 214 at this time.
Exemplarily, the first controlled current source 214 may be a current amplifier that amplifies the input current by a factor of k and then outputs it. In the safety chain device shown in
The resistive network encoder 212 is coupled with the safety chain 211. Exemplarily, as shown in
The resistive network encoder 212 has a plurality of encoder output values, and each encoder output value corresponds to one of the combinations of states of the plurality of protective switches. Taking n protective switches as an example, the number of output values may be 2n. The encoder output values of the resistive network encoder 212 are sent to the processor 213, which processes it and outputs it in the form of a digital signal (represented by a level signal Vc in
Continuing with
Optionally, the processor 213 can also be used to implement some intelligent functions, such as real-time analysis of the states of the protective switches.
Referring to
As shown in
The safety triggering mechanism 221 may for example be a relay or a switching element. When the protective switches S1-Sn are all in the closed state, the output current of the first controlled current source 214 is kxis, and under the action of this current signal, the safety triggering mechanism 221 remains closed to connect the drive motor of the escalator with the main power supply. On the other hand, when one or more of the protective switches S1-Sn is in the open state, the output current of the first controlled current source 214 is 0. At this time, the safety triggering mechanism 221 is in the open state, and the main power supply stops supplying power to the drive motor, so that the escalator stops running.
Continuing with
Those skilled in the art will appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described herein may be implemented as electronic hardware, computer software, or combinations of both.
To demonstrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented in hardware or software depends on the particular application and design constraints imposed on the overall system. Those skilled in the art may implement the described functionality in varying ways for the particular application. However, such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
Although only a few of the specific embodiments of the present application have been described, those skilled in the art will recognize that the present application may be embodied in many other forms without departing from the spirit and scope thereof. Accordingly, the examples and embodiments shown are to be regarded as illustrative and not restrictive, and various modifications and substitutions may be covered by the application without departing from the spirit and scope of the application as defined by the appended claims.
The embodiments and examples presented herein are provided to best illustrate embodiments in accordance with the present technology and its particular application, and to thereby enable those skilled in the art to implement and use the present application. However, those skilled in the art will appreciate that the above description and examples are provided for convenience of illustration and example only. The presented description is not intended to cover every aspect of the application or to limit the application to the precise form disclosed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202210228155.5 | Mar 2022 | CN | national |
