GB2063522A - Apparatus for determining elevator car position - Google Patents

Abstract

An apparatus determines the position of an elevator car 1 servicing a plurality of floors of a building. The position of the elevator car, which may move by inertia during a power service interruption, is estimated upon restoration of the power by calculating the inertia run length of the elevator car on the basis of the operation parameters including at least a car position where the elevator was positioned just before occurrence of the power service interruption and the direction of movement of the car at that time. <IMAGE>

Description

SPECIFICATION Apparatus for determining elevator car position This invention relates to an apparatus for determining the position of an elevator car.

In the control of operation of elevator cars in an elevator system, the position of each of the elevator cars is one of the important parameters, and various types of elevator car position detecting apparatus have been proposed hitherto.

One of them is a mechanical position detecting apparatus as disclosed in U.S. Patent No.

3,685,618 issued to Y. Takahashi et al on August 22, 1972 and entitled "A FLOOR SELECTOR FOR AN ELEVATOR CAR". The disclosed mechanical position detecting apparatus comprises a mechanical tracing unit adapted to move along a track of reduced scale in interlocking relation with movement of an elevator car and a plurality of elevator car position detecting switches disposed on the track of reduced scale at positions corresponding to a plurality of predetermined positions within the traveling range of the elevator car.The proposed mechanical position detecting apparatus is advantageous in that it would not fail to detect the position of the elevator car even when the elevator control system is rendered inoperative or disabled by reason of, for example, sudden temporary service interruption in the elevator power supply system, since the tracing unit can still move in mechanically interlocking relation with the elevator car until the elevator car is brought to a stop. The proposed apparatus is, however, disadvantageous in that the position of the elevator car is only discontinuously detected resulting in low accuracy of car position detection due to the fact that the track is graduated in a reduced scale and there is a limitation in the number of the detecting switches that can be mounted on the track in view of the space available for mounting.

Another elevator car position detecting apparatus proposed hitherto is of an electronic type as disclosed in U.S. Patent No. 4,046,229 issued to A. Kernick et al on September 6, 1977 and entitled "ELEVATOR SYSTEM". The proposed electronic position detecting apparatus comprises a pulse generator mounted on the shaft of the elevator car drive unit to generate a pulse each time an elevator car travels a predetermined distance and a pulse counter counting the number of pulses generated by the pulse generator so as to electronically detect the position of the elevator car. The latter apparatus can detect the position of the elevator car with high accuracy of the order of millimeters and thus contributes to desired improvements in the performance of the elevator control system.On the other hand, however, the latter apparatus tends to fail to accurately detect the position of the elevator car when the elevator control system is rendered inoperative or disabled by reason of, for example, sudden temporary service interruption in the elevator power supply system, since the pulse counting operation of the pulse counter discontinues during the period of service interruption although the elevator car may still move by, for example, inertia immediately after the service interruption has occurred.

It is therefore a primary object of the present invention to provide an apparatus for determining the position of an elevator car in which pulses generated by a pulse generator operating in interlocking relation with an elevator car drive unit are continuously counted by a pulse counter to determine the actual position of the elevator car with high accuracy, and, even when sudden service interruption may occur in the elevator power supply system resulting in temporary discontinuation of the pulse counting operation of the pulse counter although the elevator car may still move by, for example, inertia immediately after the service interruption has occurred, the distance traveled by the coasting elevator car during the period of service interruption is compensated so as not to fail to detect the position of the elevator car even in the event of service interruption.

In accordance with the present invention, there is provided an apparatus for determining the position of an elevator car servicing a plurality of floors of a building comprising pulse generator means for generating a pulse in response to movement of the elevator car for a predetermined distance, counter means for counting the pulses generated from the pulse generator means, direction detecting means for detecting the moving direction of the elevator car, means for calculating the elevator car operation parameters including the position and moving direction of the elevator car on the basis of the count registered in the counter means and the direction detected by the direction detecting means, non-volatile memory means capable of holding information stored therein even in the event of service interruption in the elevator power supply system, data transferring means for transferring the operation parameters calculated immediately before the power service interruption to the memory means upon occurrence of the power service interruption, and elevator car position determining means including means for estimating, upon power service restoration, the distance traveled by the elevator car after the service interruption on the basis of the operation parameters stored in the memory means, and means for estimating the position of the elevator car standing still at the time of the power service restoration on the basis of the traveled distance estimated by the first estimating means and the operation parameters calculated immediately before the power service interruption and stored in the memory means.

The above objects and features of the invention will be well understood from the following detailed description of preferred embodiments with reference to the accompanying drawings, in which: Fig. 1 is a block diagram showing schematically the general structure of an elevator control system in which the present invention is incorporated; Fig. 2 is a block diagram showing in detail the structure of the microcomputer which is a principal part of the elevator control system shown in Fig. 1; Fig. 3 is a flow chart of a main program executed by the microcomputer; Fig. 4 is a flow chart of a subroutine of the main program for executing the step of arithmetic processing of the position of the elevator car; Fig. 5 is a diagram illustrating one form of mapping of memory contents of the RAM and non-volatile memory in the microcomputer;; Figs. 6a and 6b show a three-phase output waveform generated by the pulse generator and a signal waveform obtained by shaping the output of the pulse generator by the waveform shaping circuit in the elevator control system shown in Fig.

1, respectively; Fig. 7 is a flow chart of a routine of interrupt processing executed by the microcomputer; Fig. 8 is a flow chart of a subroutine run in the power service restoration processing step in the flow chart of the main program shown in Fig. 4; Fig. 9 is a flow chart of a subroutine run in the step of processing for elevator car operation control in the main program shown in Fig. 4; Fig. 10 is a diagram illustrating an example of records stored in a data file; Fig. 11 is.a flow chart of a subroutine run in the step of processing for elevator car position estimation in the flow chart shown in Fig. 8; and Fig. 12 is a flow chart of a subroutine run in the step of processing for other operation control in the flow chart shown in Fig. 9.

An elevator control system in which the present invention is incorporated has a general structure as schematically shown in Fig. 1. Referring to Fig.

1, an elevator car 1 is connected to one end of and a counterweight 2 is connected to the other end of a rope which is reeved over a traction sheave 3 directly mechanically coupled to the shaft of a drive motor (not shown) through a reduction gearing (not shown), so that the elevator car 1 can be moved in either direction by the operation of the drive motor. A pulse generator 4 is also coupled to the shaft of the drive motor to generate a pulse each time the elevator car 1 travels a predetermined distance of, for example, several millimeters.

The elevator car 1 is equipped with a floor position detector 5 (which will be referred to hereinafter as an FPD) for detecting the door opening position or floor position at which the door of the elevator car 1 is to be opened for loading and unloading of passengers. The elevator car 1 is further equipped with another position detector 6 (which will be referred to hereinafter as an LPD) for detecting a specific position of the elevator car 1, for example, an end floor such as the uppermost floor or the lowermost floor. These position detectors 5 and 6 are adapted to be actuated when the elevator car 1 passes by stationary shielding members 7, 8, 9 and 10 installed in the elevator tower adjacent to the respective floor positions.

Each of the position detectors 5 and 6 is composed of, for example, a magnetic reed switch and a permanent magnet disposed opposite thereto. When any one of the shielding members 7, 8, 9 and 10 made of a soft steel plate intervenes between the magnetic reed switch and the permanent magnet with the movement of the elevator car 1, the magnetic flux emanating from the permanent magnet is obstructed from acting upon the magnetic reed switch, and the switch is thereby actuated. Each of these shielding members 7, 8, 9 and 10 has a length of about 180 mm in the moving direction of the elevator car 1, so that each position detector is actuated when it comes within the range of about 90 mm upper and lower relative to the central position of the shielding member. This range will be called a floor zone.The shielding members 9 and 10 are so disposed that, when, for example, the lowermost floor which is one of the end floors is selected as the specific position above described, the FPD 5 is actuated as it passes across the shielding member 9 at the time of landing of the elevator car 1 at the lowermost floor, and, at the same time, the LPD 6 also passes across the shielding member 10 and is actuated. Therefore, when both of the FPD 5 and the LPD 6 are simultaneously actuated, the elevator car 1 can be judged to stand at the lowermost floor. The output signals from the FPD 5 and LPD 6 are applied by way of a tail cord 11 to a microcomputer 1 3 after level adjustment in a level converter 12.

The pulse generator 4 is in the form of a unit such as a three-phase ACPG generating a threephase output waveform as described later so that the moving direction of the elevator car 1 and the distance traveled by the elevator car 1 can be simultaneously detected. The output of the pulse generator 4 is applied to the microcomputer 13 through a waveform shaping circuit 1 3.

A commercial AC power source 15 supplies DC power to the microcomputer 13 through a stabilized DC power supply 1 6 having a service interruption detecting function and through a power supply line 19. When power service interruption occurs suddenly in the elevator power supply system and lasts for more than a predetermined length of time, a power-off signal 1 8 is generated from the stabilized DC power supply 1 6 to be applied to the microcomputer 1 3.

This stabilized DC power supply 1 6 has such a capacity that the line voltage on the power supply line 1 9 can be maintained until the microcomputer 13 completes necessary processing to deal with the service interruption or power-off.

Further, the stabilized DC power supply 16 supplies power to a battery back-up unit 1 7 so that information stored in a memory may not disappear even in the event of service interruption or power-off. This battery back-up unit 1 7 supplies power by way of another power supply line 20 to a battery backed-up memory, for example, a C-RAM in the microcomputer 13 to constitute or realize a non-volatile memory. This battery back-up unit 17 is unnecessary when the memory itself is of a non-volatile type such as a core memory.

The signals processed in the microcomputer 1 3 are applied through the level converter 12 to an elevator control unit 31 connected to the AC power source 1 5 to provide various control signals 30 as described later. Under control of these control signals 30, the elevator control unit 31 controls the drive motor 32 directly coupled to the sheave 3 around which the rope supporting the elevator car 1 is reeved, so that the elevator car 1 can be stopped at any one of the predetermined positions according to a predetermined speed pattern.

As shown in Fig. 2, the microcomputer 1 3 includes a microprocessor unit 21 (which will be abbreviated hereinafter as an MPU). The MPU 21 is connected by way of a common bus 22 to a memory 23 which is rendered non-volatile by being backed up by the battery back-up unit 17 to prevent disappearance of information even in the event of power service interruption. The MPU 21 is further connected by way of the common bus 22 to a random access memory 24 (which will be abbreviated hereinafter as an RAM) and to a readonly memory 25 (which will be abbreviated hereinafter as an ROM) storing a main program and its various routines to be executed by the microcomputer 13.The MPU 21 is further connected by way of the common bus 22 to a peripheral interface 26 (which will be abbreviated hereinafter as a PIA) through which external signals, or, in this case, the output signals from the position detectors 5 and 6 are applied to the microcomputer 13 through the level converter 12 and from which the signals indicative of the results of calculation in the microcomputer 13 are applied to the elevator control unit 31 through the level converter 12. The MPU 21 is further connected by way of the common bus 22 to a phase rotation detection interface 27 (which will be abbreviated as a PRDIA) which detects the direction of rotation of the drive motor 32, hence, the moving direction of the elevator car 1.The MPU 21 is further connected by way of the common bus 22 to a programmable timer counter 28 (which will be abbreviated hereinafter as a PTM counter) which counts down unity upon reception of a pulse of the output from the pulse generator 4 and in which the count attains the full scale upon reception of a pulse after the count has been countered down to zero. Thus, when, for example, this counter 28 is a 16unit counter, its full scale is given by FFFF in hexadecimal notation.

The MPU 21 includes therein an interrupt signal receiving section which receives a timer interrupt signal generated from the timer 29 at a predetermined time interval of, for example, 32 ms and receives also the power-off signal 1 8 applied from the stabilized DC power supply 1 6.

The steps of processing carried out by the microcomputer 13 will now be described. The MPU 21 in the microcomputer 13 executes such processing steps as shown in a flow chart of Fig. 3 according to the main program recorded or stored in the ROM 25.

Referring to Fig. 3, the step 100 of processing for initialization is executed when the AC power source 1 5 is turned on. In this step 100, various flags and variables are reset, and the units including the PIA 26, PRDIA 27, PTM counter 28 and timer 29 are also reset in the microcomputer 13. The timer 28 generates the timer interrupt signal at the predetermined time interval T of, for example, 32 ms, so that the main program according to the flow chart shown in Fig. 3 can be run at the timing determined by the time interval T. In response to the generation and application of the timer interrupt signal, a timer flag is set in the RAM 24 in the microcomputer 13 in a manner as described later, and, after execution of the step 100, this step 100 is followed by the step 200.In the step 200, judgment is made as to whether or not the timer flag is set in the RAM 24 in response to the application of the timer interrupt signal.

When the result of judgment in the step 200 proves that the timer flag is set in the RAM 24, the step 200 is followed by the step 300 of data input processing. In this step 300, various input signals, for example, the output signals from the FPD 5 and LPD 6 and other signals are applied through the PIA 26 to the RAM 24 to be stored therein.

Then, the step 400 of processing for elevator car position calculation, the step 500 of processing for controlling the operation of the elevator car and the step 600 of data output processing are executed respectively in a manner as described in detail later. Upon completion of execution of all these steps, the timer flag is reset in the step 700, and the sequence returns to the step 200 to await for setting of the timer flag again. The sequence of from the step 300 of data input processing to the step 700 of timer flag resetting may be suitably altered as desired.

The step 400 of processing for the calculation the elevator car position is executed according to a subroutine as shown in Fig. 4. Referring to Fig. 4, judgment is made in the step 410 as to whether or not a power-off flag is set in an address 0 of the non-volatile memory 23 and the electromagnetic brake for braking the elevator car is actuated. As described later, the power-off flag is set in response to the application of the power-off signal 18 generated from the DC power supply 16 when service interruption in the power supply system continues for more than a predetermined length of time of, for example, 20 ms. Power service interruption lasting for a very short length of time is not regarded herein to be power-off since both the elevator drive motor 32 and the elevator control unit 31 can continue to operate without being substantially shut down. Hereinafter, power service interruption lasting for more than the predetermined duration above specified will be called power-off, and power service interruption lasting for more than the predetermined duration but a relatively short duration will be called momentary power-off. In the event of such momentary power-off, the electromagnetic brake for braking the elevator car is actuated as soon as the elevator drive power supply is turned off, but the elevator car travels or coasts still a short distance by inertia until it is completely stopped.

Until the elevator car is completely stopped, the control by the elevator control unit 31 would not ba. re-started even if the service were restored.

However, when the service is restored while the elevator car braked by the electromagnetic brake is still coasting by inertia, the control by the elevator control unit 31 will be re-started, and the microcomputer 13 will start to execute the successive steps of the main program according to the flow chart of Fig. 3. Consequently, the PTM counter 28 is reset in the step 100 to the count of FFFF. In such a case,.the above value will be added to the count of the PTM counter 28 when the distance coasted by the elevator car after the momentary power-off is calculated to estimate the position of the elevator car prior to the step 470 of processing for service restoration described later, and the elevator car will be deemed to have traveled a distance more than the actual coasted distance. In such a case, accurate estimation of the actual position of the elevator car may be impossible.To avoid such impossibility of accurate estimation of the elevator car position, the subroutine jumps from the step 410 to the step 460 without executing the detection of the position of the elevator car when the result of judgment in the step 410 proves that the elevator car is coasting, that is, the power-off flag is set and the brake is being actuated, in spite of the service restoration. It is to be noted that, although the power-off flag is set as soon as service interruption occurs, it is not reset until the step 4740 or elevator car position estimation in a subroutine of the step 470 is executed even when the service is restored, as described later.

When the result of judgment in the step 410 proves that the power-off flag is not still set or the electromagnetic brake for the elevator car is not still actuated in spite of the fact that the power-off flag is set, the step 410 is followed by the step 420. Such a situation occurs in the following cases: (1) No service interruption has occurred, and the elevator car is normally operating.

(2) Although the service has been restored after complete stoppage of the elevator car as a result of service interruption, the elevator car is being positively moved for the purpose of, for example, correcting the position of the elevator car before the step 4740 referred to above is executed.

In the step 420, the present count of the PTM counter 28 is read out, and, from this count, the previous count of the PTM counter 28 is subtracted. The latter count is stored in an address A of the RAM 24 as shown in Fig. 5. The PTM counter 28 is connected to the pulse generator 4 to count the pulses generated from the pulse generator 4. The data recorded in the address A of the RAM 24 represents thus the count read out from the PTM counter 28 during the: preceding processing cycle, that is, at the time earlier by the time interval T with which the timer interrupt signal is generated. Thus, the numerical value obtained as the result of the subtraction in the step 420 indicates the distance traveled by the elevator car between the preceding processing cycle and the present one, that is, during the time internal T.Therefore, this data has the dimension of speed and is recorded in an address F of the RAM 24 as shown in Fig. 5.

The step 420 is followed by the step 430 in which the moving direction of the elevator car is detected. For the purpose of detecting the moving direction of the elevator car, the output of the three-phase ACPG 4 having a waveform as shown in Fig. 6a is applied to the waveform shaping circuit 14 to obtain a wave-shaped signal having a waveform as shown in Fig. 6b, and such a signal is applied to the PRDIA 27. The PRDIA 27 detects that the elevator car is moving in the up-direction when the high levels of the three phases U, V and W shown in Fig. 6b appear in the order of U, V and W, while it detects that the elevator car is moving in the down-direction when the high levels appear in the order of U, W and V.When the result of detection by the PRDIA 27 in the step 430 proves that the elevator car is moving in the up-direction, an up moving flag is set in an address E of the RAM 24 shown in Fig. 5, and the step 430 is followed by the step 440. On the other hand, when the result proves that the elevator car is moving in the down direction, a down moving flag is set in the address E of the RAM 24 and the step 430 is followed by the step 450.

In the present invention, the position of the elevator car is represented by a specific value when the elevator car stands at a specific floor level, for example, the lowermost floor level at which the shielding members 9 and 10 are disposed. Therefore, the data of the present position of the elevator car is given by the sum of the specific value above described and the value of the distance traveled by the elevator car from the lowermost floor level to reach the present position. Such a data is stored in an address L of the non-volatile memory 23 shown in Fig. 5.

In the step 440, the data of the position of the elevator car detected in the preceding processing cycle is read out from the address L of the nonvolatile memory 23, and the data of the traveled distance of the elevator car obtained by the calculation in the step 420 is added to the above data to obtain the data representing the present position of the elevator car. On the other hand, in the step 450, the data obtained by the calculation in the step 420 is subtracted from the data read out from the address L to calculate the data representing the present position of the elevator car. In each of the steps 440 and 450, the content of the address L is renewed or replaced by the new position data obtained in the manner above described.In the step 460 following the step 440 or 450, the present count of the PTM counter 28 is stored in the address A of the RAM 24, and the step 460 is followed by the step 470.

When the result of judgment in the step 410 is "Yes", the subroutine jumps to the step 460 in which the present count of the PTM counter 28 is stored in the addressA of the Ram 24 and which is then followed by the step 470. The manner of processing in the step 470 will be described in detail later with reference to Fig. 8.

In the step 410, judgment is made as to whether or not the power-off flag is set in the address 0 of the non-volatile memory 23, and an interrupt processing subroutine is carried out to set this power-off flag. More precisely, as soon as an interrupt signal is generated while the microcomputer 13 is executing the processing steps 200 to 700 shown in Fig. 3, the processing routine being executed at that time is discontinued temporarily so as to execute the interrupt processing subroutine, and the microcomputer 1 3 continues to execute the temporarily discontinued processing routine upon completion of the interrupt processing subroutine.

Fig. 7 shows the subroutine executed in the interrupt processing step 1 000. In response to the application of an interrupt signal such as a poweroff signal or a timer interrupt signal to the MPU 21,judgment is made in the step 1010 as to whether or not the input signal is a timer interrupt signal. When the result of judgment in the step 1010 proves that the timer interrupt signal is applied, the step 1010 is followed by the step 1020. In this step 1020, a timer flag is set in an address B of the RAM 24 as shown in Fig. 5, and the step 1020 is followed by the step 1030.

When, on the other hand, the result of judgment in the step 1010 proves that the input signal is not the timer interrupt signal, the step 1010 is followed directly by the step 1030 in which judgment is made as to whether or not the interrupt signal is a power-off signal. When the result of judgment in the step 1030 proves that the power-off interrupt signal is applied, the step 1030 is followed by the step 1050, while when the result of judgment proves that the interrupt signal is not the power-off interrupt signal, the step 1030 is followed by the step 1040 in which other interrupt processing is carried out. The manner of processing in the step 1040 will not be described herein as it has not any direct concern with the present invention.

In the step 1050, judgment is made as to whether the power-off flag in the address 0 of the non-volatile memory 23 as shown in Fig. 5 is set or reset. When the result of judgment in the step 1 050 proves that the power-off flag is reset in the address 0, the step 1050 is followed by the step 1060 in which the data of the operation parameters such as the elevator car position, elevator car moving direction and elevator car speed detected just before the power service interruption and stored in the allotted addresses of the RAM 24 are transferred or shunt to addresses L, M and N respectively of the non-volatile memory 23. However, the data such as the elevator car position stored already in the nonvolatile memory 23 may not be shunt in the embodiment being described.

In the step 1070 following the step 1060, the power-off flag is set in the address 0 of the nonvolatile memory 23. In the step 1080 following the step 1 070, other operations are stopped until the power supply voltage applied to the microcomputer 13 is reduced to lower than the operating voltage thereby preventing re-writing of the memory contents.When the result of judgment in the step 1050 proves that the poweroff flag has already been set in the address 0 of the non-volatile memory 23, this indicates the fact that service interruption occurred therebefore lasted for a relatively short period of time, that is, momentary power-off occurred, and another service interruption has occurred again before the complete execution of the service restoration processing step 470 including the step 4740 of elevator car position estimation, upon restoration the previous momentary power-off, according to the power-off interrupt signal generated due to the previous momentary power-off.In such a case, the subroutine jumps to the step 1080 so that the data of the elevator car operation parameters may not be transferred from the RAM 24 to the nonvolatile memory 23 until the service restoration processing step 470 is completely executed to deal with the first power-off trouble which may be followed by second and succeeding power-off troubles.

Upon restoration of the service and turning on of the power supply in the microcomputer 13, the microcomputer 13 automatically starts to execute the main program according to the flow chart of Fig, 3. When a timer flag is set in the step 200 in response to the application of a timer interrupt signal, the steps proceed in the order of 200, 300 and 400. Immediately after the service restoration, the power-off flag is still set, and the elevator car is coasting or is stopped by the action of the electromagnetic brake. In such a case, the subroutine proceeds to the step 470 via the step 460 shown in Fig. 4.

The step 470 is executed according to a flow chart as shown in Fig. 8. Referring to Fig. 8, judgment is made in the step 4710 as to whether the power-off flag in the address 0 of the nonvolatile memory 23 in Fig. 5 is set or reset. When the result of judgment in the step 4710 proves that the power-off flag is reset to indicate that no service interruption has occurred or service has already been restored although service interruption occurred, the remaining steps are not executed, and the subroutine jumps to the return step 4790, so that the step 400 is followed by the step 500 in the main program shown in Fig. 3.

When, on the other hand, the result of judgment in the step 4710 proves that the power-off flag is set in the address 0, the step 4710 is followed by the step 4720 in which judgment is made whether the speed of the elevator car is zero (that is, the elevator car is stopped) or not zero (that is, the elevator car is still moving). When the result of judgment in the step 4720 proves that the elevator car is still moving, the subroutine jumps to the return step 4790 followed by the step 500 shown in Fig. 3. When, on the other hand, the result of judgment in the step 4720 proves that the elevator car is stopped, the step 4720 is followed by the step 4730 in which judgment is made as to whether the stopped position of the elevator car lies inside or outside of the floor zone or any floor on the basis of the output signal of the FDP 5 applies to the PIA 26 shown in Fig. 2.When the result of judgment in the step 4730 proves that the stopped position of the elevator car lies outside of the floor zone, the subroutine jumps to the return step 4790 followed by the step 500 shown in Fig. 3. When, on the other hand, the result of judgment proves that the stopped position of the elevator car lies inside of the floor zone, the step 4730 is followed by the step 4740 in which the position of the elevator car is estimated. Thus, in the subroutine of the service restoration processing step 470, the elevator car position estimation step 4740 is executed after confirmation of the fact that the elevator car is stopped to lie inside of the floor zone of a floor due to sudden service interruption, and in any other cases, the step 500 is executed before the execution of the step 4740.It will be readily understood that, in many cases, the step 4740 will be executed after the execution of the step 500 since the elevator car is generally stopped outside of the floor zone of a floor in the event of sudden service interruption. For the ease of understanding, therefore, the step 500 will be explained at first, and then, the step 4740 and the successive steps following it will be explained.

The subroutine of the step 500 is shown in Fig.

9. Referring to Fig. 9, judgment is made in step 501 as to whether or not the elevator car is stopped outside of the floor zone of a floor. When the result of judgment in the step 501 proves that the elevator car is stopped outside of the floor zone of the floor, the step 501 is followed by the step 502, while the result of judgment is "No", the step 501 is followed by the step 503. The step 502 sets a low-speed run flag in the address G of the RAM 24 in Fig. 5 so that the elevator car is moved downwards at a low speed at the step 600 upon reading the address G of the RAM. in the step 503, judgment is made as to whether or not the elevator car is stopped inside of any floor zone and also the low-speed run flag is set in the address G of the RAM 24.When the result of judgment in the step 503 proves that the above conditions are satisfied, the step 503 is followed by the step 504, while when the result of judgment is "NO", the step 503 is followed by the step 509. In the former case, that is, when the elevator car is moved downwards at the low speed and reaches the nearest floor zone in response to the setting of the iow-speed run flag, the low-speed run flag is reset in the step 504 so that this condition is detected at the step 600 thereby stopping the elevator car can be in the nearest floor zone. The step 504 or 503 is followed by the step 509 in which other necessary processing for controlling the elevator car operation is carried out.

It will thus be seen that, when the elevator car stops outside of any floor zone due to sudden power service interruption, the step 500 sets flags for causing the elevator car to move downwards up to the nearest floor zone. As a result, the step 600 is carried out to cause the elevator control unit 31 to operate according to the condition of the flags.

The subroutine of the elevator car position estimation step 4740 shown in the flow chart of Fig. 8 includes a plurality of steps as shown in Fig.

11. Referring to Fig. 11, the speed of the elevator car immediately before the occurrence of service interruption is multiplied by a conversion factor in the step 4742 so as to estimate the distance traveled by the coasting elevator car after the service interruption. This conversion factor may be a function of the moving direction and lead of the elevator car when a load detector is provided to detect the load of the elevator car, while it may be a constant when such a load detector is not provided. In the step 4744 following the step 4742, the moving direction of the elevator car immediately before the service interruption is judged on the basis of the moving direction flag set in the address E of the RAM 24.When the result of judgment in the step 4744 proves that the elevator car is moving in the up direction,the step 4744 is followed by the step 4746 in which the data of the traveled distance estimated in the step 4742 is added to the data of the present position of the elevator car. On the other hand, when the result of judgment in the step 4744 proves that the elevator car is moving in the down direction, the step 4744 is followed by the step 4748 in which the data of the traveled distance estimated in the step 4742 is subtracted from the data of the present position of the elevator car.

Upon detection of the estimated position of the elevator car by the steps above described, the power-off flag is reset in the step 4750 in the flow chart of Fig. 8, and the step 4750 is followed by the step 4760. Data representing the central positions of the floor zones of the individual floors, data representing the allowable range of the position of the elevator car stopped due to service interruption, data representing the central position of the actuated range of the LPD 6, and other necessary data are stored in a data file as shown in Fig. 10.

In the step 4760 in Fig. 8, the data of the estimated position of the elevator car is compared with the data filed in the data file to detect the central position of the floor zone nearest to the estimated position of the elevator car. When the result of comparison in the step 4760 proves that the difference therebetween lies within the allowable range of the position of the elevator car stopped due to service interruption, which data is also stored in the data file, the step 4760 is followed by the step 4770 in which the data of the elevator car position stored in the address L of the non-volatile memory 23 is modified to coincide with the data of the central position of the floor zone of the floor nearest to the estimated position of the elevator car.On the other hand, when the result of judgement in the step 4760 proves that the difference does not lie within the allowable range, the step 4760 is followed by the step 4780 in which an end floor run flag is set in an address H of the RAM 24 in Fig. 5 so that the elevator car can be moved to an end floor at which the LPD 6 is actuated, for the purpose of re-establishing the position of the elevator car. Such an end floor is generally the uppermost floor or lowermost floor.

However, there may be a plurality of such floors so that the position of the elevator car may be reestablished as early as possible. In the step 600 executed thereafter, a command signal is generated so as to move the elevator car toward the end floor.

The return step 4790 in Fig. 8 returns the processing subroutine executed by the microcomputer 13 to the step 500 in the main program shown in Fig. 3. Thus, the subroutine shown in Fig. 9 proceeds to the step 509, the subroutine of which is shown in Fig. 12.

Referring to Fig. 12, the elevator car operation control subroutine 509 includes the step 510 in which judgement is made as to whether or not the LPD 6 is actuated. In this case, the state of the FPD 5 is also preferably detected to improve the reliability.When the result of judgement in the step 510 proves that the LPD 6 is not actuated, the step 510 is followed by the step 540. On the other hand, when the result of judgment in the step 510 prove that the LPD 6 is actuated, the position of the elevator car is so set in the step 520 that its data coincides with the data of the central position of the actuated range of the LPD 6, which data is also stored in the data file shown in Fig. 10. In this case, the data of the floor zone, at which the LPD 6 is actuated, may be used when both the FPD 5 and the LPD 6 are actuated at the same time.In the step 530 following the step 520, the end floor run flag is reset in the address H of the RAM 24. In the step 540, the operation mode of the elevator car is set to move the elevator car towards the end floor according to the set condition of the end floor run flag or to move the elevator car under normal condition at the step 600.

It will be.understood from the foregoing detailed description that, in the apparatus of the present invention having the aforementioned construction, the data of the position, speed and moving direction of the elevator car are reliably held in the non-volatile memory 23 even in the event of momentary service interruption occurred while the elevator car is moving, and the elevator car is stopped by the action of the electromagnetic brake after coasting a short distance. When the elevator car is not located inside of the floor zone of a floor which may be nearest thereto upon restarting of power supply to the elevator car, the elevator car is run at a low speed to move into the floor zone of such a floor. At this time, the service restoration processing step 470 is executed so that the elevator car can make its normal operation when its position has been established.

When, on the other hand, the position of the elevator car has not been established at such a time, the elevator car is moved to an end floor, and after establishing the elevator car position, its normal operation is re-started.

It will therefore be appreciated that the power supply for the microcomputer need not be maintained live even in the event of sudden service interruption in the elevator power supply system, and the data of the position, speed and moving direction of the elevator car may merely be stored as necessary information. It will also be appreciated that the position of the elevator car can be simply estimated, and a relatively slight position error can be easily corrected.

Claims (11)

1. An apparatus for determining the position of an elevator car servicing a plurality of floors of a building comprising: pulse generator means for generating a pulse in response to movement of said elevator car for a predetermined distance; counter means for counting the pulses generated from said pulse generator means; direction detecting means for detecting the moving direction of said elevator car; means for calculating the elevator car operation parameters including the position and moving direction of said elevator car on the basis of the count registered in said counter means and the direction detected by said direction detecting means; non-volatile memory means capable of holding information stored therein even in the event of service interruption in the elevator power supply system;; data shunting means for shunting said operation parameters calculated immediately before the service interruption to said memory means upon occurrence of the service interruption; and elevator car position determining means including means for estimating, upon service restoration, the distance traveled by said elevator car after the service interruption on the basis of said operation parameters stored in said memory means, and means for estimating the position of said elevator car standing still at the time of the service restoration on the basis of said traveled distance estimated by said first estimating means and said operation parameters calculated immediately before the service interruption and stored in said memory means.

2. An apparatus as claimed in Claim 1 further comprising: detector means provided at each of said plural floors for detecting approach of said elevator car; and means for permitting the operation of said elevator car position determining means when any one of said detector means is found to be actuated, said means permitting the operation of said elevator car position determining means after movement of said elevator car until any one of said detector means is actuated when none of said detector means are found to be actuated.

3. An apparatus as claimed in Claim 2, wherein said apparatus further comprises a data file for storing, in individually separate relation, the data of the central positions of the floor zones in each of which the associated one of said detector means is actuated when said elevator car moves into that zone, and wherein said elevator car position determining means includes means for comparing the data of the estimated position of said elevator car with the data of the central positions of the floor zones stored in said data file and modifying, on the basis of the result of comparison, the estimated elevator car position data so that it coincides with the data of one of the central positions of the floor zones which is nearest to the estimated car position among those stored in said data file.

4. An apparatus as claimed in Claim 3, wherein said apparatus further comprises a second detector means disposed at a known position within the traveling range of said elevator car to be actuated when said elevator car moves to a position close thereto, and wherein said estimated elevator car position data modifying means includes means for modifying said estimated elevator car position data to make it coincide with the data of the central position of the nearest floor zone when the difference therebetween is smaller than a predetermined value, and means for modifying said estimated elevator car position data after movement of said elevator car to the position at which said second detector means is actuated, thereby making said estimated elevator car position to coincide with said known position when said difference exceeds the predetermined value.

5. An apparatus as claimed in Claim 1, wherein said operation parameters include the position, speed and moving direction of said elevator car.

6. An apparatus as claimed in Claim 5, wherein the speed of said elevator car is represented by a change in the count of said counter means which counts the pulses generated at a predetermined time interval from said pulse generator means.

7. An apparatus as claimed in Claim 5, wherein said elevator car position estimating means estimates the position of said elevator car by multiplying the speed parameter among said operation parameters calculated immediately before the service interruption by a conversion factor and adding or subtracting the resultant value to or from said position parameter when said moving direction parameter indicates that said elevator car is moving in the up or down direction.

8. An apparatus as claimed in Claim 7, wherein said conversion factor is a function of the load and moving direction of said elevator car our a constant

9. An apparatus as claimed in Claim 1, wherein said apparatus further comprises means for temporarily discontinuing the operation of said operation parameter calculating means in the event of service interruption, said operation parameter calculating means including a second memory means for storing the data of said operation parameters and means for cyclically calculating said operation parameters at a constant time internal and successively renewing the contents of said second memory means with the newly calculated data of said operation parameters, and said data shunting means reads out the data of said operation parameters stored in said second memory means so as to store the thus read-out data in said first memory means when said discontinuing means is actuated.

10. An apparatus as claimed in claim 1, further comprising means for inhibiting the operation of said data shunting means when another service interruption is detected before said elevator car position determining means completes its operation.

11. An apparatus substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.