Patent Publication Number: US-10766742-B2

Title: Hydraulic elevator safety device, and method for detecting open-door travel abnormality in hydraulic elevator

Description:
TECHNICAL FIELD 
     The present invention relates to a safety device for a hydraulic elevator with an open-door running prevention function and a method of detecting an open-door running abnormality of a hydraulic elevator, for a hydraulic elevator configured to cause a car to run in a vertical direction by controlling a hydraulic pressure. 
     BACKGROUND ART 
     As related-art open-door running prevention units for a hydraulic elevator, there have been proposed a braking method using an emergency stop device (see, for example, Patent Literature 1), a method using a dual check valve (see, for example, Patent Literature 2), and the like. 
     Each of the open-door running prevention units monitors a position of a car or a speed of the car in an open-door state to determine an abnormal state and performs a braking operation for the car. 
     CITATION LIST 
     Patent Literature 
     [PTL 1] JP 2013-184799 A 
     [PTL 2] JP 4767193 B2 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, the related art has the following problem. In the hydraulic elevator, the car is liable to be shaken in response to a vibration force applied inside the car. Therefore, when the car is shaken due to a prank done by a passenger, the speed of the car sometimes becomes excessively higher than needed. 
     Therefore, an abnormality detection speed is required to be set with a tolerance for a speed at the time when the car is shaken so that the open-door running prevention unit is prevented from being erroneously operated due to the shaking of the car caused by the prank. Even when the car is braked based on the abnormality detection speed with the tolerance as described above, the car can be braked with a distance between a car doorway and a hoistway doorway being set such that the passenger is not caught therein. 
     When the abnormality detection speed is set with the tolerance, however, a deceleration of the car is undesirably increased due to an increase in maximum speed of the car until the braking operation for the car is started. As a result, there is a fear in that the passenger is injured by the braking operation. Thus, it is desired to decrease the deceleration of the car. 
     The present invention has been made to solve the problem described above, and has an object to provide a safety device for a hydraulic elevator and a method of detecting an open-door finning abnormality of a hydraulic elevator, which are capable of detecting an abnormal downward movement state at a car speed lower than a car speed set for related-art devices and performing car braking processing, thereby decreasing a deceleration of a car and reducing a stopping distance. 
     Solution to Problem 
     According to one embodiment of the present invention, there is provided a safety device for a hydraulic elevator, including: an open-door running prevention unit, which is configured to determine presence or absence of an open-door running abnormality based on a detection value of a car speed when the hydraulic elevator is in an open-door state, and to perform car braking processing when it is determined that the open-door running abnormality is present; and a pressure sensor, which is configured to detect a pressure value on a side of a check valve provided in a hydraulic pipe, which is close to a hydraulic tank, in which the open-door running prevention unit includes a memory configured to sequentially store values of the pressure sensor during a period, in which the hydraulic elevator is in the open-door state as time-series data, in which the open-door running prevention unit determines whether or not the car speed detected when the hydraulic elevator is in the open-door state is equal to or larger than a preset first threshold value, in which, when it is determined that the car speed is equal to or larger than the first threshold value, the open-door running prevention unit calculates a differential value between a maximum value and a minimum value of the time-series data stored in the memory in a period from a current time at which the car speed becomes equal to or larger than the preset first threshold value to preset determination time, and in which, when the differential value is out of a preset allowable range, the open-door running prevention unit determines that the the open-door running abnormality is present, and executes the car braking processing. 
     Further, according to one embodiment of the present invention, there is provided a method of detecting an open-door running abnormality for a hydraulic elevator, which is to be executed by an open-door running prevention unit included in a safety device for a hydraulic elevator, the open-door running prevention unit being configured to determine presence or absence of an open-door running abnormality based on a detection value of a car speed when the hydraulic elevator is in an open-door state and perform car braking processing when it is determined that the open-door running abnormality is present, the method including: a first step of sequentially storing values of a pressure sensor configured to detect a pressure value on a side of a check value provided in a hydraulic pipe, which is close to a hydraulic tank; a second step of determining whether or not the car speed detected when the hydraulic elevator is in the open-door state is equal to or larger than a preset first threshold value; a third step of, when it is determined that the car speed is equal to or larger than the first threshold value in the second step, calculating a differential value between a maximum value and a minimum value of the time-series data stored in the memory in a period from a current time at which the car speed becomes equal to or larger than the first threshold value to preset determination time, and determining whether or not the differential value is out of a preset allowable range; and a fourth step of, when it is determined that the differential value is out of the preset allowable range in the third step, determining that the open-door running abnormality is present, and executing the car braking processing. 
     Advantageous Effects of Invention 
     According to the present invention, the abnormal downward movement state can be reliably detected after a car shaking state and the abnormal downward movement state are distinguished from each other in accordance with a magnitude of a detection value of the pressure of the hydraulic pipe between the check valve and the hydraulic tank when the car speed becomes equal to or larger than a set threshold value. As a result, there can be provided a safety device for a hydraulic elevator and a method of detecting an open-door running abnormality of a hydraulic elevator, which are capable of detecting an abnormal downward movement state at a car speed lower than a car speed set for related-art devices and perform car braking processing, thereby decreasing a deceleration of a car and reducing a stopping distance. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an overall configuration diagram of a hydraulic elevator of a first embodiment of the present invention. 
         FIG. 2  is a graph for showing a temporal change in car speed, a temporal change in detection pressure of a jack port pressure sensor, and a temporal change in detection pressure of a pressure sensor for determination when an abnormality is present in the hydraulic elevator of the first embodiment of the present invention. 
         FIG. 3  is a graph for showing a temporal change in car speed, a temporal change in detection pressure of the jack port pressure sensor, and a temporal change in detection pressure of the pressure sensor for determination when a car is shaken under a stopped state with doors open in the hydraulic elevator of the first embodiment of the present invention. 
         FIG. 4  is a flowchart for illustrating determination processing for a car shaking state and car braking control processing performed along with the determination processing, which are executed by a safety device for a hydraulic elevator according to the first embodiment of the present invention. 
         FIG. 5  is a graph for showing a comparison between a car speed waveform when the car is braked with the safety device for a hydraulic elevator according to the first embodiment of the present invention and that with a related-art device. 
         FIG. 6  is an overall configuration diagram of a hydraulic elevator of a second embodiment of the present invention. 
         FIG. 7  is an overall configuration diagram of a hydraulic elevator of a third embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Now, description is made of a safety device for a hydraulic elevator and a method of detecting an open-door running abnormality of a hydraulic elevator according to exemplary embodiments of the present invention with reference to the drawings. 
     First Embodiment 
       FIG. 1  is an overall configuration diagram of a hydraulic elevator of a first embodiment of the present invention. The hydraulic elevator of the first embodiment employs a method of controlling a downward movement operation through control of the number of revolutions of a motor. 
     In  FIG. 1 , inside a hoistway, a hydraulic jack  1  is installed. The hydraulic jack  1  includes a cylinder  2  fixed to a bottom portion inside the hoistway and a plunger  3  vertically movable relative to the cylinder  2 . A deflector sheave  4  is provided to an upper end portion of the plunger  3  so as to be freely rotatable. 
     A hydraulic power unit  5  configured to control a hydraulic pressure applied to the cylinder  2  is coupled to the cylinder  2  through a hydraulic pipe  6 . The hydraulic power unit  5  of the first embodiment includes a check valve  41 , a hydraulic pump  42 , a drive motor  43 , a tank  44 , a jack port pressure sensor  45 , and a pressure sensor  46  for determination. 
     The check valve  41  is provided between the cylinder  2  and the hydraulic pump  42 , and is configured to prevent a reverse flow of oil to maintain a hydraulic pressure. The hydraulic pump  42  is driven by the drive motor  43  and is configured to feed the oil stored in the tank  44  to the cylinder  2 . The jack port pressure sensor  45  and the pressure sensor  46  for determination are described later. 
     The hydraulic pressure applied to the cylinder  2  is controlled by rotating the hydraulic pump  42  in a forward direction or a reverse direction with a driving force of the drive motor  43 . The drive motor  43  is controlled by a control panel  32 . The check valve  41  is controlled to be opened during a period in which a running operation is being performed, and to be closed in a stopped state. The plunger  3  is vertically moved relative to the cylinder  2  by the control of the hydraulic pressure applied to the cylinder  2 . 
     A suspension body  8  configured to suspend a car  7  is caused to run over the deflector sheave  4 . As the suspension body  8 , for example, a rope or a belt is used. One end portion of the suspension body  8  is connected to the car  7 , and another end portion of the suspension body  8  is connected to a fixed portion inside the hoistway. Inside the hoistway, a pair of guide rails (not shown) extending in a vertical direction is installed. The car  7  runs in the vertical direction while being guided by each of the guide rails through the vertical movement of the plunger  3 . 
     In an upper part of the hoistway, an upper sheave  11  is provided. In a lower part of the hoistway, a lower sheave  12  is provided. A rope  13  for detection is caused to run over the upper sheave  11  and the lower sheave  12  in a looped manner. One end portion and another end portion of the rope  13  for detection are connected to the car  7 . The rope  13  for detection is moved in accordance with running of the car  7  in the vertical direction. The upper sheave  11  and the lower sheave  12  are rotated in accordance with the movement of the rope  13  for detection. 
     An encoder  14  configured to detect a position of the car  7  is provided to a rotary shaft of the upper sheave  11 . The encoder  14  generates a signal in accordance with the rotation of the upper sheave  11 . The position of the car  7  is detected based on the signal generated in accordance with the rotation of the upper sheave  11 . 
     A car doorway  21  is provided to the car  7 . The car doorway  21  is opened and closed by movement of a pair of car doors  22  along a width direction of the car doorway  21 . Each of the doors  22  of the car is moved by a driving force of a door drive device (not shown) mounted to the car  7 . 
     A landing doorway  23  is provided to a landing on each floor. The landing doorway  23  is opened and closed by movement of a pair of landing doors  24  along a width direction of the landing doorway  23 . When the car  7  is stopped within a predetermined landing range, the landing doors  24  and the car doors  22  are mechanically engaged with each other in a horizontal direction by engagement devices (not shown). The landing doorway  23  is opened and closed by the movement of the landing doors  24  held in engagement with the car doors  22 . 
     A landing door switch  25  configured to detect opening of the landing doorway  23  is provided to each landing doorway  23 . Each landing door switch  25  detects that the landing doorway  23  is closed when the landing doors are located at positions at which the landing doorway  23  is fully closed. Each landing door switch  25  detects that the landing doorway  23  is opened when the landing doors  24  are located out of the positions at which the landing doorway  23  is fully closed. 
     A car door switch (not shown) configured to detect opening of the car doorway  21  is provided. The car door switch detects that the car doorway  21  is closed when the car doors  22  are located at positions at which the car doorway  21  is fully closed. The car door switch detects that the car doorway  21  is opened when the car doors  22  are located out of the positions at which the car doorway  21  is fully closed. 
     An open-door running prevention unit  31  detects the position of the car  7 , running of the car  7 , a running distance of the car  7 , a running direction of the car  7 , and a speed of the car  7  based on information from the encoder  14 . Further, the open-door running prevention unit  31  detects whether or not at least any of the car doorway  21  and the landing doorways  23  is opened based on information from the car door switch and the landing door switches  25 . 
     Then, the open-door running prevention unit  31  determines whether or not the car  7  is running with the doors open and controls power fed from the hydraulic power unit  5  based on the results of detections described above. 
     Next, the jack port pressure sensor  45  and the pressure sensor  46  for determination included in the hydraulic power unit for a purpose of detecting a car shaking state are described. 
     The jack port pressure sensor  45  is provided between the hydraulic jack  1  and the hydraulic power unit  5 . Further, the pressure sensor  46  for determination is provided between the check valve  41  and the hydraulic pump  42  which is installed on a side close to the tank  44 . 
     The open-door running prevention unit  31  determines the car shaking state based on the result of detection by the pressure sensor  46  for determination.  FIG. 2  is a graph for showing a temporal change in car speed, a temporal change in detection pressure of the jack port pressure sensor  45 , and a temporal change in detection pressure of the pressure sensor  46  for determination when an abnormality is present in the hydraulic elevator of the first embodiment of the present invention. 
     Meanwhile,  FIG. 3  is a graph for showing a temporal change in car speed, a temporal change in detection pressure of the jack port pressure sensor  45 , and a temporal change in detection pressure of the pressure sensor  46  for determination when the car is shaken under the stopped state with doors open in the hydraulic elevator of the first embodiment of the present invention. 
     When an abnormality is present in the check valve  41  and an abnormal downward movement state in which the car  7  is lowered is brought about, a pressure loss is generated due to a flow of the oil through the hydraulic pump  42 . Therefore, an output of the jack port pressure sensor  45  and an output of the pressure sensor  46  for determination are varied as shown in  FIG. 2  along with an increase in speed of the car  7 . 
     In contrast to the above-mentioned case, when the check valve  41  has no abnormality, and the car  7  is shaken due to a prank done by a passenger, the output of the pressure sensor  46  for determination remains unvaried although the speed of the car  7  and the output of the jack port pressure sensor  45  are varied as shown in  FIG. 3 . Therefore, the open-door running prevention unit  31  can determine that an abnormality is absent in the check valve  41  when the output of the pressure sensor  46  for determination is not varied even though the speed of the car  7  increases or is varied. 
       FIG. 4  is a flowchart for illustrating determination processing for the car shaking state and car braking control processing performed along with the determination processing, which are executed by the safety device for a hydraulic elevator according to the first embodiment of the present invention. The processing illustrated in  FIG. 4  is periodically called so as to be repeatedly executed by the open-door running prevention unit  31 . 
     After the processing is started, the open-door running prevention unit  31  stores an output value of the pressure sensor  46  for determination in a memory in Step S 401 . Next, in Step S 402 , the open-door running prevention unit  31  determines whether or not the elevator is in an open-door state based on an operation of the landing door switch  25 . 
     When the elevator is in a closed-door state, the open-door running prevention unit  31  terminates a processing series in this cycle. Meanwhile, when the elevator is in the open-door state, the processing proceeds to Step S 403  where the open-door running prevention unit  31  determines whether or not the output of the encoder  14  configured to detect the speed of the car is equal to or larger than a threshold value VL. 
     When it is determined that the speed of the car is not equal to or larger than the threshold value VL, the open-door running prevention unit  31  terminates the processing series in this cycle. Meanwhile, when it is determined that the speed of the car is equal to or larger than the threshold value VL, the processing proceeds to Step S 404  where the open-door running prevention unit  31  calculates a difference ΔPC between a maximum value and a minimum value of the outputs of the pressure sensor  46  for determination, which are stored in the memory in a period from a current time to determination time TL. 
     As an example of setting of the determination time TL, the determination time TL only needs to be set to a time period about twice to about four times as long as a period of a natural frequency of a target hydraulic elevator. Then, in Step S 405 , the open-door running prevention unit  31  determines whether or not the difference ΔPC between the maximum value and the minimum value of the outputs of the pressure sensor  46  for determination is out of a preset allowable range as a range including the speed being equal to zero. 
     Then, when it is determined that the difference ΔPC is out of the allowable range, the processing proceeds to Step S 406  where the open-door running prevention unit  31  determines that the open-door finning abnormality is present. Further, in Step S 407 , the open-door running prevention unit  31  quickly executes braking processing for the car  7  and then terminates the processing series. 
     Meanwhile, when it is determined that the difference ΔPC falls within the allowable range, the open-door running prevention unit  31  determines that an abnormality is absent in the check valve  41 . Even in this case, however, there still is a fear of presence of an abnormality in the pressure sensor  46  for determination or an abnormality which cannot be determined only based on the difference ΔPC falling within the allowable range. 
     Therefore, when the open-door running prevention unit  31  determines that the difference ΔPC falls within the allowable range, the processing proceeds to Step S 408  where it is further determined whether or not the car speed is equal to or larger than a threshold value VH. Here, the threshold value VH is a value larger than the threshold value VL and is preset as an abnormality detection speed with a tolerance with respect to a speed when the car is shaken as in the case of related-art devices. 
     Then, even when the open-door running prevention unit  31  determines that the speed of the car  7  is equal to or larger than the threshold value VH, the processing proceeds to Step S 406  where it is determined that the open-door running abnormality is present. Further, in Step S 407 , the open-door running prevention unit  31  quickly executes the braking processing for the car  7  and then terminates the processing series. 
     As described above, the determination processing using the threshold value VH as in the related art is performed in Step S 408 . As a result, the car  7  can be braked with a distance between the car doorway and the hoistway doorway being set to a distance with which the passenger is not caught therein, as in the related art. 
       FIG. 5  is a graph for showing a comparison between a car speed waveform when the car is braked with the safety device for a hydraulic elevator according to the first embodiment of the present invention and that with the related-art device. The solid line in  FIG. 5  represents the speed waveform of the present invention, and the dotted line in  FIG. 5  represents the speed waveform with the related-art device. 
     In the case of the related-art device, the presence or absence of the abnormality is determined based on the speed of the car  7  exceeding the threshold value VH. Therefore, from the determination of the abnormality to the start of operation of a braking device, a lowering speed for the car  7  is increased and then, a decelerating operation is performed. 
     Meanwhile, the safety device for the hydraulic elevator according to the first embodiment, at the time when the speed of the car exceeds the threshold value VL set as the speed lower than the threshold value VH, the difference APC is calculated to perform the determination processing. Therefore, an increase in speed of the car until the start of operation of the braking device can be held smaller than that with the related-art device. As a result, a deceleration of the car to stop the car can also be decreased, and hence the running distance until the stop can also be reduced. 
     As described above, according to the first embodiment, the abnormal downward movement state can be reliably detected after the car shaking state and the abnormal downward movement state are distinguished from each other based on the speed lower than that used in the related-art devices. As a result, the abnormality detection speed can be decreased. Thus, the deceleration of the car can be made smaller than that with the related-art devices, and a stopping distance can be shortened. Therefore, the safety device for a hydraulic elevator, which is capable of executing more quick and appropriate car braking processing, can be provided. 
     Second Embodiment 
       FIG. 6  is an overall configuration diagram of a hydraulic elevator of a second embodiment of the present invention. The configuration of  FIG. 6  of the second embodiment differs from the configuration of  FIG. 1  of the first embodiment described above in an internal configuration of the hydraulic power unit  5 . Therefore, differences of the hydraulic power unit  5  are mainly described below. 
     The hydraulic power unit  5  of the second embodiment includes the tank  44 , the jack port pressure sensor  45 , the pressure sensor  46  for determination, and a control valve  51 . The control valve  51  includes a check valve  52  and a piston  53 . 
     Specifically, the hydraulic power unit  5  of the second embodiment employs a method of controlling the lowering operation with an opening degree of the control valve  51  instead of controlling the hydraulic pump  42  and the drive motor  43 . 
     The pressure sensor  46  for determination is provided between the check valve  52  and the piston  53 . Specifically, the pressure sensor  46  for determination of the second embodiment is provided on a side of the check valve  52 , which is close to the tank, as in the case of the first embodiment described above. Then, when the car is abnormally lowered, the output of the pressure sensor  46  for determination is varied due to a pressure loss generated by an internal resistance of the piston  53  or the control valve  51 . 
     Therefore, even with the configuration of  FIG. 6  described above, the same effects can be obtained by performing the determination processing using the threshold value VL for the output of the pressure sensor  46  for determination as in the case of the first embodiment described above. 
     Third Embodiment 
       FIG. 7  is an overall configuration diagram of a hydraulic elevator of a third embodiment of the present invention. The configuration of  FIG. 7  of the third embodiment differs from the configuration of  FIG. 1  of the first embodiment described above in an internal configuration of the hydraulic power unit  5 . Therefore, differences of the hydraulic power unit  5  are mainly described below. 
     The hydraulic power unit  5  of the third embodiment further includes a dual check valve  61  in addition to the check valve  41 , the hydraulic pump  42 , the drive motor  43 , the tank  44 , the jack port pressure sensor  45 , and the pressure sensor  46  for determination. 
     The dual check valve  62  is used under a closed state. Therefore, in place of the pressure sensor  46  for determination of the first embodiment described above, a second pressure sensor  46   a  for determination may be provided between the dual check valve  61  and the check valve  41 . In  FIG. 7 , there is exemplified a case where the pressure sensor  46  for determination and the second pressure sensor  46   a  for determination are both provided. 
     Therefore, even with the configuration of  FIG. 7  described above, the same effects can be obtained by performing the determination processing using the threshold value VL for the output of the pressure sensor  46  for determination or for the output of the second pressure sensor  46   a  for determination as in the case of the first embodiment and the second embodiment described above.