EP2349899B1 - Device for checking a safety chain of an elevator - Google Patents

Description

From the publication EP 1 090 870 A1 a lift device is known with a safety chain for a lift, wherein the safety chain consists of a series connection of contacts, a safety relay, a voltage converter and a monitor, wherein the signal of the safety relay is fed to an elevator control. A voltage to be regulated across the safety relay is supplied to a network of the elevator device, which is connected to the voltage converter. The voltage converter, the series circuit and the network form a control circuit which checks the voltage across the safety relay and keeps it constant when all contacts of the series circuit are closed. As a result, the safety circuit operates independently of an output voltage of a voltage source, which is subject to voltage fluctuations.

Out US-B1-6,193,019 a device is known in which resistors with different resistance values are connected in parallel with the switch elements of an elevator safety chain. This makes it possible, in the case of an open switching element, to determine which switching element is involved or which elevator door has a fault.

Out WO-A-2008/081074 An elevator safety device is known in which resistors with different resistance values are also connected in parallel to switching elements of a safety chain. By detecting the resistance values of the safety chain it can be determined whether more than one shaft door is open, which indicates an unauthorized intrusion of a person into the elevator shaft.

Out WO 2006/108433 Safety chains for passenger conveyors are known in which by means of resistance measurement, capacitance measurement or measurement of a transit time of a reflected pulse signal, the position and thus the identity of an open switching element can be detected.

The object of the invention is in particular to provide a device by means of which a reliable operation of a hardware component, in particular the safety chain of an elevator, can be achieved with less effort. The The object is achieved according to the invention by a test device having the features of patent claim 1, by an elevator device having the features of claim 9 and by a hardware monitoring method having the features of claim 14. Further refinements and developments of the invention can be taken from the subclaims.

A test device is proposed which serves for monitoring an elevator device or a component of an elevator, in particular a composite resistance of an elevator device. This test device comprises at least one hardware monitoring unit, which is provided to monitor at least one functionally relevant composite resistor. By "hardware" in particular at least one material component, such as a sensor, to be understood. A "hardware monitoring unit" is to be understood in particular as meaning a unit which, in at least one operating mode, carries out a check and / or examination of at least one property of at least one component and / or detection of at least one physical variable and / or, particularly preferably, one arithmetic unit , a storage unit and a storage unit stored operating program for monitoring. By "provided" is to be understood in particular specially equipped and / or designed and / or programmed. A resistance is to be understood as meaning a material element which sets up a resistance to an electrical current flowing through this element, which is referred to below as a resistance value. A "function-relevant" resistor is to be understood, in particular, as a resistance element whose quality, in particular its resistance value, is considerable for at least one function of a device which contains the resistor. A "composite" resistor is to be understood in particular as meaning a resistor resulting from an interconnection of at least two individual resistance elements. Such a composite resistor may for example consist of all individual resistance forming switching elements of a safety chain of a lift. The individual resistors arranged in such a safety chain are formed in particular by output switching elements of sensors which detect sensors states, in particular positions, of elevator components important for the safety of the elevator operation. Such output switching elements of sensors are preferably present in the form of electronic or mechanical switches, in particular in the form of output switching contacts. Under the fact that the hardware monitoring unit "monitors" a resistor should be understood in particular that the hardware monitoring unit, in particular at different times at least one feature of the resistance quantitatively and / or qualitatively examined. With an embodiment according to the invention, a device can be achieved to achieve reliable operation of the safety chain. In particular, a test device with a unit can be achieved for detecting functionally hazardous changes in the nature of interacting hardware components and in particular a chain of interconnected individual resistances. In particular, the detection of a functionally hazardous increase of the forward resistance values of electrical output switching elements of sensors of a safety chain of an elevator can be achieved.

The hardware monitoring unit of the test device comprises at least one detection unit with at least one current measuring unit and / or at least one voltage measuring unit and / or at least one resistance measuring unit. hereby a structurally simple design of the hardware monitoring unit can be achieved.

It is also proposed that the detection unit is provided to detect at least one resistance characteristic variable serving to determine function-threatening changes in the properties of the resistor at specific time intervals or continuously. Such a resistance characteristic is understood in particular to mean a physical quantity which can be used to calculate a resistance value or which directly indicates the resistance value of the resistance. Examples of such resistance parameters are an electrical voltage applied to the resistor and a current strength present in the resistor. In this way, a reliable monitoring of the nature of the functionally relevant resistance can be achieved.

Advantageously, the current measuring unit is designed as an induction current measuring unit. In this way, a contactless measurement of the current in a line carrying the current can be achieved. In particular, introduction of a measuring resistor into this line, for example in the safety chain of an elevator, can be avoided.

In a preferred embodiment of the invention, the hardware monitoring unit or the detection unit present in the monitoring unit has at least one comparison unit, which is provided to compare a resistance characteristic variable with at least one reference variable. As a result, a simple quantitative monitoring can be achieved.

Preferably, the hardware monitoring unit or the detection unit comprises at least one calibration unit, which is intended to generate the reference variable for the resistance characteristic, preferably automatically. In this way, a simple commissioning of the test device can be achieved. In particular, a determination of the reference variable by an installer can be avoided.

Advantageously, the hardware monitoring unit or the detection unit has at least one output unit which is provided to emit at least one signal if an impermissibly strong change in the nature of the monitored hardware component, for example an inadmissibly large increase in a resistance characteristic value or the resistance value a functionally relevant, composite resistor is detected. In this way, in particular the functional reliability of the composite resistance-containing device, for example, a monitored by a safety chain elevator can be achieved. In particular, a maintenance requirement of the composite resistor, for example a safety chain, can be signaled and preventive maintenance can be initiated. In particular, inoperability of the hardware component, such as the functionally relevant resistor, can be prevented. In particular, the signal of the output unit also wireless, such. B. by radio, and in particular by SMS and / or e-mail.

In addition, an elevator device is proposed which comprises at least one safety chain in operative connection with an elevator control and at least one test device. A "safety chain" should in particular be understood to mean at least two series-connected output switching elements of sensors, which sensors each detect an operating state of a device of an elevator. The testing device has at least one hardware monitoring unit which, in at least one operating mode, monitors at least one functionally relevant quality of at least one hardware component of the safety chain. A "functionally relevant" quality of a hardware component is to be understood as a property of the hardware component which influences at least one function of a device having this hardware component. A "quality" of a hardware component is to be understood in particular as a property of the hardware component which has or assumes this as a result of environmental influences acting on it and / or chemical and / or physical processes. Under the fact that the hardware monitoring unit "monitors" a condition of a hardware component is to be understood in particular that the hardware monitoring unit, in particular at different times at least one property or a feature of the nature of the Hardware component quantitatively and / or qualitatively checked. With an embodiment of the elevator device according to the invention, it is possible to achieve the recognition of functionally hazardous changes in the quality of cooperating hardware components, in particular of interconnected resistors. In particular, the elevator device can signal the need for preventive maintenance of a safety chain so that preventive maintenance can ensure reliable operation of a safety chain, for example the safety chain of an elevator.

The hardware monitoring unit belonging to the testing device of the elevator device comprises at least one detection unit, which detects at least one resistance characteristic in the at least one operating mode, which serves to determine the resistance value of the safety chain or directly indicates its resistance value. This allows a structurally simple monitoring of the nature of the safety chain can be achieved.

Advantageously, the resistance characteristic value detected by the detection unit is the resistance value of the entire safety chain. In this way, a cost-effective design can be achieved. In particular, a complex monitoring of individual resistances can be dispensed with.

The detection unit preferably has at least one current measuring unit and / or at least one voltage measuring unit and / or at least one resistance measuring unit. This allows a structurally simple design of the detection unit can be achieved.

Furthermore, it is proposed that the current measuring unit is designed as an induction current measuring unit. In this way, a contactless measurement of the current can be achieved. In particular, introduction of a measuring resistor into a line unit which carries the current can be avoided.

Advantageously, in the at least one operating mode, the detection unit detects at least one resistance characteristic variable at specific time intervals or continuously. This allows reliable monitoring of the nature of the hardware components, For example, the output switching elements of the sensors of the safety chain can be achieved.

In addition, it is proposed that the hardware monitoring unit belonging to the testing device of the elevator device of the elevator device has at least one comparison unit which compares the resistance characteristic variable with at least one reference variable in the at least one operating mode. As a result, a simple quantitative monitoring of the nature of the hardware components, in particular the output switching elements of the sensors of the safety chain can be achieved.

In a preferred embodiment variant, the hardware monitoring unit belonging to the testing device of the elevator device has at least one calibration unit which generates the reference variable in the at least one operating mode. In this way, a simple start-up of the elevator device can be achieved. In particular, a determination of the reference variable by an installer can be avoided.

During the elevator operation, a safety chain voltage, preferably taken from the elevator control, is transmitted via the safety chain, an interruption of this safety chain voltage, for example by an output switching element of one of the sensors of the safety chain, being detected by a control unit belonging to the elevator device. In such a case, this control unit causes the elevator controller to stop the elevator operation. It is therefore preferably integrated in the elevator control or arranged in its area and can supply a safety chain voltage originating from the elevator control or contain its own voltage source for the safety chain voltage. The safety chain voltage is applied to the safety chain at least during a majority of the total operating time and causes a current flow in the safety chain when all output switching elements of the safety chain sensors are conductive.

In one possible embodiment of the invention, the current flow occurring when the safety chain is not interrupted is used to monitor the condition of the hardware components, in particular for monitoring the resistance value of the in Series switched output switching elements used by sensors. In this case, at least the total resistance value of the entire safety chain is determined from the voltage across the conductive output switching elements of the sensors, for example via a chain of closed output switching contacts, and the detected current intensity. With suitable detection devices and additional characteristics of the transmitted voltage and / or the current flow occurring can be registered and evaluated.

In a particularly preferred embodiment of the invention, the hardware monitoring unit belonging to the testing device of the elevator device has at least one separate monitoring voltage source. From this separate monitoring voltage source, a measuring voltage is applied to the safety chain for monitoring the condition of the hardware components of the safety chain, in particular for monitoring the total resistance value of the series-connected output switching elements of sensors of the safety chain. During normal elevator operation, the separate monitoring voltage source is disconnected from the safety chain, while the monitoring voltage taken from the elevator control described above is applied to the safety chain. To carry out a measurement process for monitoring the condition of the hardware components of the safety chain, the separate monitoring voltage source is preferably connected to the safety chain at a time when all the output elements of the safety chain sensors are conductive. Such a measuring operation advantageously takes place during a standstill of the elevator and lasts less than 10 seconds, preferably less than a second. During the measuring process, the mentioned monitoring voltage applied in normal operation over the safety chain is disconnected from the safety chain and preferably every movement of the elevator by the elevator control is prevented.

In this way, in the at least one operating mode, a separate monitoring voltage source can be coupled to the safety chain, which is more suitable for monitoring the nature of the hardware components than the voltage source which is connected to the safety chain during operation of the safety chain. As a result, a usability of a matched voltage and in particular an improved quality of the evaluation of the measuring process for monitoring the nature of the hardware components can be achieved.

The hardware monitoring unit preferably has at least one output unit which generates a signal when the change in the condition of the hardware components is detected, in particular when the resistance value of the series-connected output switching elements of the safety chain is changed. This signal is used to inform the elevator maintenance staff about a required maintenance of the safety chain. As a result, a preventive maintenance of the safety chain can be ensured. In particular, the risk of business interruption of the elevator device, and in particular of a lift in which the elevator device is installed, can be reduced. The signal can also be wireless, such. B. by radio, and in particular by SMS and / or e-mail to a maintenance organization.

It is also proposed that the elevator device has at least one trip unit which activates the hardware monitoring unit. This tripping unit is preferably integrated into the hardware monitoring unit belonging to the test device of the elevator device. Since the hardware monitoring is feasible only if all output switching elements contained in the safety chain are conductive, the activation is preferably carried out at a defined time of day, which usually takes place little elevator traffic, or if the safety chain has not been interrupted for a long period of time. In this way, it can be achieved that the short interruption of the elevator operation required for the hardware monitoring can not be perceived as a fault.

Preferably, at least one of the sensors of the safety chain is designed as a mechanical limit switch, in which a probe element actuates an electrical output switching contact. This allows a simple construction of the sensor can be achieved. However, the sensors can also be designed, for example, as inductive or capacitive switches, magnetic switches (reed switches), light sensors or light barriers, pressure switches, etc.

Furthermore, a monitoring method is proposed, in particular for monitoring at least part of an elevator device. In this monitoring method, at least one function-relevant condition of at least one hardware component of a safety chain is monitored in at least one operating mode. In particular, the said hardware component is at least two series-connected output switching elements of sensors of the safety chain. Due to the monitoring method, a particularly reliable functioning of the safety chain and thus of the elevator can be achieved.

Furthermore, a hardware monitoring method, in particular with a test device, is proposed, in which a functionally relevant, composite resistance is monitored by means of a continuous or periodic measurement of the total resistance value. By initiating a preventive maintenance upon detection of an inadmissibly increased total resistance value, a particularly reliable functioning of the safety chain of an elevator and thus of the elevator itself can be achieved.

Further advantages emerge from the following description of the drawing. In the drawings, embodiments of the invention are shown. The drawing, the description and the claims contain numerous features in combination. The skilled person will conveniently consider the features individually and summarize meaningful further combinations.

Fig. 1

eine schematische Darstellung einer Aufzugsvorrichtung,

Fig. 2

einen Aufzug mit der Aufzugsvorrichtung,

Fig. 3

eine schematische Darstellung eines Vergleichs einer Widerstandskenngrösse mit einer Referenzgrösse,

Fig. 4

einen Zeitstrahl, welcher eine Betriebszeit der Aufzugsvorrichtung darstellt,

Fig. 5

eine schematische Darstellung eines alternativen Ausführungsbeispiels einer Aufzugsvorrichtung mit einer separaten Überwachungs-Spannungsquelle, und

Fig. 6

eine weitere schematische Darstellung eines alternativen Ausführungsbeispiels mit einer Induktions-Strommesseinheit.

Show it:

Fig. 1

a schematic representation of an elevator device,

Fig. 2

an elevator with the elevator device,

Fig. 3

1 is a schematic representation of a comparison of a resistance characteristic variable with a reference variable,

Fig. 4

a timeline which represents an operating time of the elevator device,

Fig. 5

a schematic representation of an alternative embodiment of an elevator device with a separate monitoring voltage source, and

Fig. 6

a further schematic representation of an alternative embodiment with an induction current measuring unit.

Fig. 1 shows a schematic representation of an inventive elevator device 1, which comprises a safety chain 10 with three series-connected output switching elements (output switching contacts) 12.1, 14.1, 15.1 of sensors 12, 14, 15 and a test device 11 with a control unit 44 and a hardware monitoring unit 16. A detection unit 20 of the hardware monitoring unit 16 includes a resistance measuring unit 34, which is formed by a current measuring unit 30 and a voltage measuring unit 32.

When installed, the elevator device 1 is part of an elevator. Fig. 2 shows such an elevator with the elevator device. The elevator has elevator shaft doors 48, 50 and a cabin door 52. With the car door 52, a car 54 of the elevator can be closed, which is provided for a transport of loads and persons. The sensors 12, 14, 15 are each assigned to one of the door locking elements 86, 88, 90 of the elevator shaft doors 48, 50 or the cabin door 52. If one of the elevator shaft doors 48, 50 or the cabin door 52 is closed and locked, the electrical output switch contact 12.1, 14.1, 15.1 (in FIG Fig. 2 not shown) of this door associated sensor 12, 14, 15 closed. If one of the elevator shaft doors 48, 50 or the cabin door 52 is at least partially open or unlocked, the electrical output switch contact 12.1, 14.1, 15.1 of the sensor 12, 14, 15 associated with this door is open. Only in a state in which the output switching contacts 12.1, 14.1, 15.1 of all sensors of the safety chain 10 are closed and functional and the safety chain 10 thus conducts electrical current, can an elevator control 45 recognize the condition of the elevator as safe and operate the elevator, ie , a movement of the cab 54 relative to the elevator shaft doors 48, 50 release. In order to detect whether this safe state is present, a voltage is applied to the safety chain of the elevator device 1 during normal operation of the elevator. This voltage causes a current flow when the output switching contacts 12.1, 14.1, 15.1 of all sensors 12, 14, 15 of the safety chain 10 are closed. When the current flow is detected by the control unit 44, it signals the elevator controller 45 that movement of the car 54 is allowed. The control unit 44 is integrated in this embodiment in the lift control 45 shown by dashed lines.

In at least one mode of operation, the hardware monitoring unit 16 monitors at least one functionally relevant nature of the hardware components 18 formed by the sensors 12, 14, 15. In principle, the safety chain 10 conducts electrical current when the output switching elements of all sensors 12, 14, 15 of the safety chain 10 are conductive, ie, when the output switching contacts 12.1, 14.1, 15.1 of in Fig. 1 and 2 shown sensors 12, 14, 15 are closed. In order that, in a safe state of the elevator, current can actually flow through the safety chain 10, the output switching elements or the output switching contacts 12.1, 14.1, 15.1 of the sensors 12, 14, 15 must be functional. This means that with each sensor of the safety chain the electrical resistance of its output switching element or its output switching contact must not exceed a permissible value if the sensor detects the safe state of the elevator component monitored by it (eg a door locking element). This ensures that the series-connected output switching elements or output switching contacts allow a clearly detectable by the control unit 44 current flow through the safety chain 10. For this purpose, for example, designed as electrical output switching contacts 12.1, 14.1, 15.1 output switching elements of the sensors 12, 14, 15 must be free of significant contamination and free of much oxidized contact points so that they do not form high contact resistance in the safety chain in the conductive state.

For monitoring the function-relevant contact resistances of the output switching contacts 12.1, 14.1, 15.1 of the sensors 12, 14, 15, which together form a resistor 17, the detection unit 20 detects in the at least one operating mode a resistance characteristic variable, which can be, for example, the total resistance value 22 of the safety chain 10 , The total resistance value of the safety chain 10 is that resistance value which has the row of the output switching contacts 12.1, 14.1, 15.1 of the sensors 12, 14, 15 of the safety chain 10 in total when all the output switching contacts of the sensors are in a closed state.

The current measuring unit 30 has an output 46, which is connected to an input 58 of the control unit 44. Furthermore, an input 60 of the current measuring unit 30 is connected to an end 76 of the safety chain 10, namely the sensor 12. An output 56 of the control unit 44 is conductive with one end 78 of the safety chain 10-namely with the sensor 15 - connected. In addition, an input 62 of the voltage measuring unit 32 is conductively connected to the output 56. An output 64 of the voltage measuring unit 32 is connected to the input 58 of the control unit 44. The voltage measuring unit 32 measures a voltage which is applied between the output 56 and the input 58 of the control unit 44 in the state in which the safety chain 10 in principle conducts electrical current. In addition, the current measuring unit 30 measures the current of the current flowing through the safety chain 10 when the safety chain 10 is in the state in which it conducts electric current in principle, and by means of the control unit 44, a voltage to the input 58 and the output 56th is created. If at least the output switching contact 12.1, 14.1, 15.1 of one of the sensors 12, 14, 15 too dirty and / or oxidized, the safety chain 10 leads in this situation only a stream of reduced current or no power. From the measured current intensity and the measured voltage, the hardware monitoring unit 16 determines the total resistance value 22 of the safety chain 10.

The hardware monitoring unit 16 of the test device 11 has a comparison unit 24, which compares the resistance characteristic variable, in the present case the measured total resistance value 22, with a reference variable 26 in the at least one operating mode (FIG. Fig. 3 ). The reference variable 26 corresponds to the total resistance value which the safety chain 10 has in the case of unpolluted and unoxidized output switching contacts 12.1, 14.1, 15.1 of the sensors 12, 14, 15, in particular immediately after a first startup of the elevator device. The reference variable 26 is measured in the at least one operating mode, in particular immediately after the first startup of the elevator device by the hardware monitoring unit 16, which comprises a calibration unit 28, and stored in a memory unit 66 of the comparison unit 24. After detection of the total resistance value 22, which is performed after measuring the reference variable 26, the comparison unit 24 compares the measured total resistance value 22 of the safety chain with the reference value 26 and signals a maintenance requirement of the sensors 12, 14 to an output unit 40 integrated in the hardware monitoring unit 16 , 15 when the total resistance value 22 deviates from the reference value 26 by more than a certain percentage. Upon receipt of the maintenance request signal, the output unit 40 notifies an elevator maintenance organization or a maintenance person by means of a telephone or radio link. The maintenance person can then remove any possible contamination and / or oxidation and / or other impairment of the output switching contacts of the sensors 12, 14, 15, before a further increase in the total resistance value of the safety chain 10 leads to an interruption of the elevator operation.

In the embodiment of the test device according to Fig. 1 detects the detection unit 20, the resistance characteristic value or the total resistance value 22 during all phases of the operating time in which all output switching contacts of the sensors of the safety chain are closed, ie, in all phases in which the current measuring unit detects a current flow. Fig. 4 shows a timeline which begins with a completion of the first start-up of the elevator device. Immediately after the first startup, the reference variable 26 is measured at a time 68. The resistance characteristic value or the total resistance value 22 is measured, for example, during the above-mentioned phases 69 of the operating time 67 after the time 68 and compared with the reference variable 26.

The hardware monitoring unit 16 of the test device 11 has a computing unit, a memory unit and an operating program stored in the memory unit.

In principle, the safety chain 10 may have further electrical contacts which serve, for example, to monitor a brake of the elevator. The elevator device 1 can also be retrofitted in an existing elevator or in existing elevator systems.

In the Fig. 5 and 6 Two alternative embodiments of an elevator device are shown. Substantially identical components, features and functions are basically numbered by the same reference numerals. To distinguish the embodiments, however, the reference numerals of the embodiments in the Fig. 5 and 6 added the letters "a" and "b" respectively. The following description is essentially limited to the differences from the embodiment in the Fig. 1 to 4 , wherein with respect to the same components, features and functions on the description of the embodiment in the Fig. 1 to 4 is referenced.

In the Fig. 5 Lift device 1a shown comprises a test device 11a with a control unit 44a and a safety chain 10a, wherein the control unit and the Safety chain preferably form part of the elevator control 45a of an elevator. Furthermore, the test device 11a comprises a hardware monitoring unit 16a with a detection unit 20a and a switching relay 70a with two switching contacts 70.1a, 70.2a. During operation of the elevator, a safety chain voltage is applied to the safety chain 10a via the control unit 44a of the elevator control 45a. In a state in which the output switching elements of the sensors 12a, 14a, 15a designed as electrical contacts are closed, a current flows through the safety chain 10a, which for example activates a safety relay 38a of the control unit 44a, which signals to the elevator control 45a that a transport of Persons and / or loads safely with the elevator is possible. The control unit 44a has a time measuring unit 74 which measures a time duration during which the current flows uninterruptedly through the safety chain 10a. If this time duration exceeds a certain value, then a trip unit 42a of the control unit 44a activates the hardware monitoring unit 16a and the switching relay 70a with the switch contacts 70.1a, 70.2a. The switch contacts 70.1a, 70.2a then disconnect the safety chain 10a from the control unit 44a and connect one end 76a of the safety chain 10a to an input 80a of the hardware monitoring unit 16a and another end 78a of the safety chain 10a to an output 82a of the hardware monitoring unit 16a. Thereby, a voltage generated by a monitor power source 84a present in the hardware monitor unit 16a is applied to the safety chain 10a. A current measuring unit 30a and a voltage measuring unit 32a of the detection unit 20a form a resistance measuring unit 34a which determines a total resistance value of the safety chain 10a. This is achieved by the current measuring unit 30a measuring the current flow generated by the voltage source 84a, the resistance measuring unit 34a measuring the monitoring voltage applied to the safety chain during the measuring process and the detection unit determining the current total resistance value of the safety chain from the measured current intensity and the measured monitoring voltage. As related to above Fig. 1 described, the determined total resistance is compared in a comparison unit 24a with a stored reference value, whereupon optionally the comparison unit of an output unit 40a signals an inadmissibly high total resistance value. After detection of the total resistance value, preferably lasting less than 10 seconds, the switching relay disconnects the safety chain 10a from the detection unit 20a and places the safety chain back on the control circuit 44a of the elevator control 45a Safety chain voltage on. If the hardware monitoring unit 16a is activated due to the length of time during which the security chain is not interrupted, then a measurement of the total resistance value preferably takes place at night, since lift usage rarely takes place in this period. In principle, it is also conceivable that the control unit 44a recognizes in another way that the elevator is unused and then initiates disconnection of the safety chain 10a from the safety chain voltage and coupling to the monitoring voltage source of the hardware monitoring unit 16a. Furthermore, it is conceivable that the detection of the total resistance value 22 is limited to a fixed number of measurements per unit of time, for example, one measurement per day at a time at which the elevator is barely used according to experience.

Fig. 6 shows a further embodiment of an elevator device 1 b with a control unit 44b, safety chain 10b, and a hardware monitoring unit 16b with a detection unit 20b. The operation of the elevator device 1 b corresponds essentially to the mode of action of the associated with the Fig. 1 and 2 described elevator device. The detection unit 20b here has a current measuring unit 30b, which is designed as an induction current measuring unit. If a current flows through the safety chain 10b, a current is induced in the current measuring unit 30b, by means of which the current measuring unit 30b calculates the current intensity of the current flowing through the safety chain 10b. Ends 76b, 78b of the safety chain 10b are conductively connected directly to the control unit 44b.

Claims (10)

1. Checking device (11; 11a; 11b) for checking an elevator apparatus (1; 1a; 1b) of an elevator, wherein the checking device comprises at least one hardware monitoring unit (16; 16a; 16b) which is provided for monitoring at least a functionally relevant, composite resistance (17; 17a; 17b), wherein the hardware monitoring unit (16; 16a; 16b) contains at least one sensing unit (20; 20a; 20b) which comprises at least one current-measuring unit (30; 30a; 30b) and/or at least one voltage-measuring unit (32; 32a; 32b) and/or at least one resistance-measuring unit (34; 34a; 34b),
   characterized
   in that the checking device (11; 11a; 11b) is provided for detecting a function-endangering increase in the forward resistance values of electrical output switching elements (12.1, 14.1, 15.1; 12.1a, 14.1a, 15.1a; 12.1b, 14.1b, 15.1b) of sensors (12, 14, 15; 12a, 14a, 15a; 12b, 14b, 15b) of a safety chain of an elevator.
2. Checking device according to Claim 1,
   characterized in that
   the hardware monitoring unit (16; 16a; 16b) has an output unit (40; 40a; 40b) which is provided for outputting at least one signal if an unaccepted large increase in the resistance value of the functionally relevant composite resistance is detected.
3. Checking device according to one of Claims 1 or 2,
   characterized in that
   the hardware monitoring unit (16; 16a; 16b) has at least one comparison unit (24; 24a; 24b) which is provided for comparing a resistance characteristic variable (22) with at least one reference variable (26).
4. Checking device according to one of Claims 1 to 3,
   characterized in that
   the current-measuring unit (30; 30a; 30b) is embodied as an induction current-measuring unit.
5. The checking device as claimed in one of Claims 3 or 4,
   characterized by
   at least one calibration unit (28; 28a; 28b) which is provided for generating the reference variable (26).
6. Elevator device (1; 1a; 1b) having a checking device (11; 11a; 11b) according to one of Claims 1 to 5 and at least one safety chain (10; 10a; 10b) which has at least two output switching elements (12.1, 14.1, 15.1; 12.1a, 14.1a, 15.1a; 12.1b, 14.1b, 15.1b), connected in series, of sensors (12, 14, 15; 12a, 14a, 15; 12b, 14b, 15b), wherein
   the checking device (11; 11a; 11b) has at least one hardware monitoring unit (16; 16a; 16b) which, in at least one operating mode, monitors at least one functionally relevant quality of at least one hardware component (18; 18a; 18b) of the safety chain (10; 10a; 10b), and
   the hardware monitoring unit (16; 16a; 16b) has at least one sensing unit (20; 20a; 20b) which, in the at least one operating mode, senses at least one resistance characteristic variable (22) which serves to determine the overall resistance value of the safety chain (10; 10a; 10b) or specifies the overall resistance value thereof,
   characterized in that
   the checking device is provided for detecting a function-endangering increase in the forward resistance values of electrical output switching elements of sensors of a safety chain of an elevator.
7. Elevator device (1; 1a; 1b) according to Claim 6, characterized by at least one monitoring voltage source (84a).
8. Elevator device (1; 1a; 1b) according to one of Claims 6 or 7, characterized by at least one triggering unit (42b) which, during at least one operational sequence, activates the hardware monitoring unit (16b) during a specific time period of uninterrupted conducting of current through the safety chain (10b).
9. Elevator device (1; 1a; 1b) according to one of Claims 6 to 8,
   characterized in that
   at least one of the sensors (12, 14, 15; 12a, 14a, 15a; 12b, 14b, 15b) comprises an output switching element which is embodied as an electrical output switching contact (12.1, 14.1, 15.1; 12.1a, 14.1a, 15.1a; 12.1b, 14.1b, 15.1b).
10. Hardware monitoring unit, in particular having a checking device (11; 11a; 11b) according to one of Claims 1 to 5, in which a functionally relevant composite resistance (17; 17a; 17b) of a safety chain (10; 10a; 10b) of an elevator control (45; 45a) is monitored in order to detect the function-endangering increase in the forward resistance values of electrical output switching elements of sensors of a safety chain of an elevator.

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