HK1183471B

HK1183471B - Switch detection system

Info

Publication number: HK1183471B
Application number: HK13110789.9A
Authority: HK
Inventors: Gang Xing
Original assignee: Otis Elevator Company
Filing date: 2010-06-02
Publication date: 2016-08-05

Description

Switch detection system

Technical Field

The subject matter disclosed herein relates to control systems, and in particular to switch detection systems for elevator and escalator control systems.

Background

The switch detection system may include a plurality of switches electrically connected to the control system. The switch detection system may be used to determine whether a switch in the system has been actuated and to identify which particular switch is actuated.

The determination and identification of the actuated switch can be used to control a system such as an elevator or escalator system.

Disclosure of Invention

According to one aspect of the invention, a switch detection system comprises: a first switch having a pole node, a normally closed contact, and a normally open contact, the pole node of the first switch being connected to a voltage source node; a second switch having a pole node, a normally closed contact, and a normally open contact, the pole node of the second switch being connected to the normally closed contact of the first switch; a voltage detector connected to the normally closed contact of the second switch; a first resistor connected to a normally open contact of the first switch; a second resistor connected to the normally open contact of the first switch and the normally open contact of the second switch; and a processor having a first connection connected to the pole node of the first switch and a second connection connected to the first resistor.

According to another aspect of the invention, a method for determining an actuated switch in a system comprises: receiving an indication from a voltage detector that the voltage detector is not detecting a voltage; measuring a voltage in a circuit comprising at least one switch and at least one resistor connected in series; determining a resistance of the circuit; dividing the resistance of the circuit by the known resistance of the at least one resistor to determine the number of resistors in series in the circuit; correlating the number of resistors in series in the circuit with the number of corresponding switches in the circuit; identifying an actuated switch in the system in response to correlating a number of resistors in series in the circuit with a number of corresponding switches in the circuit; outputting a signal indicative of the identified actuated switch.

According to yet another aspect of the present invention, a switch detection system includes: a first switch having a pole node, a normally closed contact, and a normally open contact, the pole node of the first switch being connected to a voltage source node; a second switch having a pole node, a normally closed contact, and a normally open contact, the pole node of the second switch being connected to the normally closed contact of the first switch; a first resistor connected to a normally open contact of the first switch; and a second resistor connected to the normally open contact of the first switch and the normally open contact of the second switch.

These and other advantages and features will become more apparent from the following description when taken in conjunction with the accompanying drawings.

Drawings

The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates an exemplary embodiment of a switch detection system.

The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.

Detailed Description

Fig. 1 illustrates an exemplary embodiment of a switch detection system 100. The system 100 includes switches (S1-Sn) 102 in a switch array 101, and the switch array 101 may include any number (n) of switches 102. In the illustrated embodiment, each switch 102 includes a first pole 150 and a second pole 151 connected to form a single pole node 153, a normally closed contact 160, and a normally open contact 161. These contacts are arranged so that when the normally closed contact 160 is open, the normally open contact 161 is closed. The pole node 153 of the switch 102 and the normally closed contact 161 of the switch are connected in series between the voltage source (Vs) node 104 and the voltage detector 106. Similar (or substantially identical) resistors (R1-Rn) 108 are arranged in series in the resistor array 103. Each of the resistors 108 is paired with a corresponding switch 102 such that the system 100 includes n number of switches and resistors. Array 103 includes nodes (W1-Wn) 105 disposed between resistors 105 (node Wn is disposed at the ends of the series of resistors 108); each node 105 connects each resistor 108 to a normally open contact 161 of the counterpart switch 102. Switch identification circuit 107 includes a node 109 connected to R1 resistor 108, a node 111 connected to voltage source node 104, and may include a node 113 connected to Wn node 105. Terminal 109 is connected to a resistor 110 connected to ground. The terminal 113 may be connected to a voltage source (Vtest) via a test switch (Stest) 112. The processor 114 is communicatively connected to the switch identification circuit 107 and the voltage detector 106.

In operation, the voltage detector 106 detects the voltage from the voltage source node 104 when each of the normally closed contacts 160 of the switch 102 is in a closed position. The voltage detector 106 may send a signal to the processor 114 indicating the detected voltage from the voltage source node 104. When the switch 102 (e.g., switch S2102) is actuated, the normally closed contact 160 of the switch S2102 is opened, and the normally open contact 161 of the switch S2102 is closed. The electrical connection between the voltage source node 104 and the voltage detector 106 is broken and the voltage detector 106 will not detect a voltage. The voltage detector 106 may send a signal to the processor 114 indicating that no voltage is detected. The closing of normally open contact 161 of switch S2102 causes a current path to flow from voltage source node 104 through normally closed contact 160 (closed) of switch S1102, normally open contact 161 (closed) of switch S2102, resistor R2108, resistor R1108, and node 109 to processor 114. The processor 114 senses the voltage source (Vs) at the voltage source node 104 (at node 111) and the resistance voltage (Vr) at the node 109. Because resistors 108 have similar resistances, Vr = Vs/n + 1. Solving for n, n = Vs/Vr-1, where n is the number of resistors 108 connected in series when the switch 102 is actuated (normally open contact 161 closed and normally closed contact 160 open). Because each switch 102 is paired with a resistor 108, the actuated switch can be identified.

In the above example, actuation of switch S2102 results in a loss of voltage to voltage detector 106. The voltage detector 106 sends a signal to the processor 114. The processor 114 detects the voltages Vs and Vr and solves the above equation for n. The resulting n =2 indicates the presence of two resistors (R1 and R2) connected in series. Since each resistor 108 is paired with a switch 102, n =2 indicates that switch S2102 has been actuated. The indication of a particular actuated switch 102 may be used by the processor 114 to control an associated system, such as an elevator or escalator system. For example, the processor 114 may output control signals to control visual, audio, or other non-textual indicators in the system, or may output control signals to control mechanical elements of the system, such as an elevator car.

The Stest switch 112 may be used to test the system. If the normally closed contact of switch 102 is closed, the Stest switch 112 may be closed and a voltage may be applied across the resistor array 103. If the system 100 is operating correctly, the total resistance (Rt) of the resistor array 103 should be detected, where Rt = ∑ Rn. The processor 114 may compare Rt to a threshold resistance value. If Rt is less than the threshold, the processor may indicate a fault in the system by, for example, outputting a fault message to an operator, illuminating a fault indicator light (not shown), or implementing control logic associated with the fault.

While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

Claims

1. A switch detection system (100), comprising:

a first switch (102) having a pole node (153), a normally closed contact (160), and a normally open contact (161), the pole node (153) of the first switch (102) connected to a voltage source node (104);

a second switch (102) having a pole node (153), a normally closed contact (160), and a normally open contact (161), the pole node (153) of the second switch (102) being connected to the normally closed contact (160) of the first switch (102);

a voltage detector (106) connected to a normally closed contact (160) of the second switch (102);

a first resistor (108) connected to a normally open contact (161) of the first switch (102);

a second resistor (108) connected to a normally open contact (161) of the first switch (102) and a normally open contact (161) of the second switch (102); and

a processor (114) having a first connection connected to a pole node (153) of the first switch (102) and a second connection connected to the first resistor (108).

2. The system of claim 1, wherein the system further comprises a third switch (112) connected to the processor (114) and a normally open contact (161) of the second switch (102).

3. The system of claim 1, wherein the voltage detector (106) is operative to detect a voltage and to send an indication of the detected voltage to the processor (114).

4. The system of claim 1, wherein the first resistor (108) and the second resistor (108) have similar resistances.

5. The system of claim 1, wherein the first resistor (108) and the second resistor (108) have the same resistance.

6. The system of claim 1, wherein the processor (114) is operative to:

receiving a signal from the voltage detector (106) indicating that the voltage detector (106) is not detecting a voltage;

determining a voltage across a first connection of the processor (114) and a second connection of the processor (114);

determining a voltage drop across a connection of the processor (114); and

calculating a number of resistors (108) in series between the first connection of the processor (114) and the second connection of the processor (114).

7. The system of claim 2, wherein the processor is operative to:

closing the third switch (112);

applying a voltage across the first resistor (108) and the second resistor (108);

measuring a total resistance of the first resistor (108) and the second resistor (108);

comparing the measured resistances of the first resistor (108) and the second resistor (108) to a threshold resistance; and

indicating a fault in response to determining that the measured resistance is less than the threshold resistance.

8. A method for determining an actuated switch in a system (100), the method comprising:

receiving an indication from a voltage detector (106) that the voltage detector is not detecting a voltage;

measuring a voltage in a circuit comprising at least one switch (102) and at least one resistor (108) connected in series;

determining a resistance of the circuit;

dividing the resistance of the circuit by the known resistance of the at least one resistor (108) to determine the number of resistors (108) in series in the circuit;

correlating a number of resistors (108) in series in the circuit with a corresponding number of switches (102) in the circuit;

identifying an actuated switch (102) in the system in response to correlating a number of resistors (108) in series in the circuit with a number of corresponding switches (102) in the circuit;

outputting a signal indicative of the identified actuated switch (102).

9. A switch detection system comprising:

a second resistor (108) connected to a normally open contact (161) of the first switch (102) and a normally open contact (161) of the second switch (102).

10. The switch detection system of claim 9, wherein the system further comprises a processor (114) having a first connection connected to a pole node (153) of the first switch (102) and a second connection connected to the first resistor (108).

11. The switch detection system of claim 10, wherein the system further comprises a voltage detector (106) connected to a normally closed contact (160) of the second switch (102).

12. The system of claim 10, wherein the system further comprises a third switch (112) connected to the processor (114) and a normally open contact (161) of the second switch (102).

13. The system of claim 11, wherein the voltage detector (106) is operative to detect a voltage and to send an indication of the detected voltage to the processor (114).

14. The system of claim 9, wherein the first resistor (108) and the second resistor (108) have similar resistances.

15. The system of claim 9, wherein the first resistor (108) and the second resistor (108) have the same resistance.

16. The system of claim 10, wherein the processor is operative to:

determining a voltage across the first connection of the processor (114) and the second connection of the processor (114);

determining a voltage drop across a connection of the processor (114); and

17. The system of claim 16, wherein the processor (114) is operative to receive a signal from a voltage detector (106) indicating that the voltage detector (108) is not detecting a voltage prior to determining a voltage across the first connection of the processor (114) and the second connection of the processor (114).

18. The system of claim 12, wherein the processor is operative to:

closing the third switch (112);