Patent Publication Number: US-5893433-A

Title: Elevator car position detecting apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an elevator car position detecting apparatus for detecting the position of an elevator car when the car is near one of the ends of the path of the elevator. 
     2. Description of the Prior Art 
     Japanese Patent Application Laid-open No. 62-280174 describes an elevator car position detecting apparatus as illustrated in FIG. 4. Referring to the figure, arms 2a to 2e are horizontally projected from a wall 1 of the path along which an elevator car 6 is moved up and down. The arms 2a to 2e are arranged vertically in order of length. More specifically, the lowest arm 2a is the shortest, and the uppermost arm 2e is the longest. A cam 3 is fixed to the end portions of the arms 2a to 2e and has inclined portions 3a to 3d. A switch 5 is attached to the car 6. 
     The switch 5 comprises: a roller 50 which is associated with the cam 3 as the car 6 ascends; a lever 51 which turns about a fulcrum 52 when the roller 50 is associated with the cam 3; springs 52a and 52b connected to a lower portion of the lever 51 so as to maintain the lower portion of the lever substantially in the vertical posture when the roller 50 does not receive an external force; and switch box 54 containing switches (described below) which are operated as the lever 51 turns. 
     Components contained in the switch box 54 will be described with reference to FIG. 5. The lever 51 is connected at the lower end to a horizontal bar 53. Contacts 51a to 51d are connected to the horizontal bar 53. A contact 54a faces the contact 51a, spaced from the contact 51a by an air gap g1. Similarly, contacts 51b to 54d face the contacts 53b to 53d, spaced by air gaps g2 to g4, respectively. The size relation of the air gaps g1 to g4 are: 
     
         g1&lt;g2&lt;g3&lt;g4 
    
     The four pairs of contacts, 51a and 54a to 51d and 54d, form four separate switches 55a to 55d. 
     The operation of the above-described conventional elevator car position detecting apparatus will be described. 
     When the car 6 is far from the top end of the path and therefore the roller 50 is not associated with the cam 3, the lever 51 assumes a vertical posture (as shown in FIG. 5) and all the switches 55a to 55d are off. When the roller 50 becomes associated with the inclined portion 3a of the cam 3 as the car 6 ascends, the lever 51 turns in the direction indicated by the arrow R in FIG. 5 and thus connects the switch 55a. The switch-on signal thus generated is sent to a control unit (not shown), thus informing that the car has reached the inclined portion 3a. As the car 6 further ascends so that the roller 3a is associated with the inclined portion 3b, the lever 51 further turns in the direction indicated by the arrow R, thus connecting the switch 55b. In the same manner, as the roller 50 becomes associated sequentially with the inclined portions 3c and 3d, the lever 51 further turns to sequentially connect the switches 55c and 55d. In this manner, the switch-on signals generated by the switches 55a to 55d inform the control unit that the car 6 has reached the corresponding positions. 
     Then, as the car 6 descends from the top position, the switch 55d is first disconnected, and the switch 55a is last disconnected. The control unit thus monitors the position of the car 6. 
     Although the above description has been made with reference to the case where the car 6 is near the top terminal floor, it will be easily understood, without further description, that the position of the car 6 can be monitored in a similar manner when the car 6 is near the bottom terminal floor. 
     The above Japanese Patent Application Laid-open No. 62-280174 also describes a position detecting apparatus comprising: a detector which is attached to an elevator car and has a light emitter and a light receiver; and a stepped light-shielding plate which is attached to the path of the elevator car and insertable into a gap between the light emitter and the light receiver without contacting either the light emitter or receiver. The patent application further states that such a position detecting apparatus can also be achieved by utilizing magnetism, for example, employing a magnetism-shielding plate instead of the light-shielding plate. 
     However, because the above-described conventional detecting apparatuses employing cams connected to the paths of the elevator cars detect the position of an elevator car on the basis of the positions of the inclined portions of the cam, the size of the gap between the elevator car and the wall of the path significantly affects the precision of the position detection, thus requiring precise installation and adjustment of the elevator, which is not easy. Even if precise installation and adjustment is achieved, the gap size varies as the elevator is used. In several years, the detection precision deteriorates to such a level that re-adjustment is required. Further, the conventional apparatus produces noise when the roller contacts the cam. The noise problems can be eliminated by a non-contact position detecting apparatus. However, both the contact and non-contact types require as many cam surfaces or shielding plates as the positions to be detected, and as many detection elements, e.g., switches. To increase the number of positions to be detected, the number of these components must be proportionally increased. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide an elevator car position detecting apparatus which achieves accurate and precise detection, facilitates installation of the apparatus and the elevator, achieves quiet operation, and requires fewer detection elements than the positions to be detected. 
     To achieve the above objects, according to one aspect of the present invention, there is provided an elevator car position detecting apparatus comprising: a plurality of plates provided at each of operation points in such arrangement that one operation point is distinguishable from another operation point; and a position detector which is provided on a car and which is associable with the corresponding plates without contacting the plates and generates a signal indicating that the car has reached one of the operation points when associated with one of the plates. 
     In the above elevator car position detecting apparatus, each operation point is encoded by the plates provided at the operation point in such arrangement that one operation point is distinguishable from another operation point, and a detection signal is generated by a position detector when it is associated with a plate. The apparatus thus determines that the elevator car has reached an operation point on the basis of a detection signal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front elevation of an elevator car position detecting apparatus according to an embodiment of the present invention. 
     FIG. 2 is a plan of the elevator car position detecting apparatus shown in FIG. 1, illustrating the operation thereof. 
     FIG. 3 is a front elevation of the apparatus shown in FIG. 2. 
     FIG. 4 is a schematic front elevation of a conventional elevator car position detecting apparatus. 
     FIG. 5 illustrates in detail components contained in the switch box shown in FIG. 4. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates an embodiment of the present invention. Components the same as or comparable to those shown in FIG. 4 are denoted by the same numerals and will not be described again. Horizontal arms 62a to 62e are projected from the path wall 1 near the top terminal floor. The arm 62a is disposed at the lowest position, and the arm 62e at the uppermost position. All the arms 62a to 62e have substantially the same lengths. The arms 62a to 62e have top plates 9a-9c, 10a-10c, 11a-11c, 12a-12c and 13a-13c, respectively, which are substantially perpendicular to a plane of the sheet. The top plates 9a to 9c connected to the lowest arm 62a encode the first top operation point. A plurality of top operation points are arranged along the path of the car 6. The top plates 10a to 10c connected to the second lowest arm 62b encode the second top operation point. In the same manner, the top plates 11a-11c, 12a-12c and 13a-13c encode the third, fourth and fifth top operation positions, respectively. 
     Because the three top plates on one arm differ from the three top plates on another arm in horizontal arrangement (or positions), each top operation point is distinguishable from the other top operation points. 
     Naturally, this elevator car position detecting apparatus further comprises bottom plates and other components provided near the bottom terminal floor. Their arrangements and functions should be easily understood with reference to the above description and will not be described herein. 
     A position detector unit 6 (described later) is attached to a mount table 7 and comprises magnetic position detectors 8a to 8f. The position detectors 8a to 8e have approximately &#34;U&#34;-shapes having recesses. If the recesses of the position detectors receive top (or bottom) plates, the magnetism therein is blocked, thus turning off the position detectors. 
     The operation of this embodiment of the present invention will be described hereinafter with reference to FIGS. 1, 2 and 3. When the position detectors 8a to 8f reach the first top operation point during ascent of the car 6 toward the top terminal floor, the top plates 9a to 9c relatively enter the corresponding position detectors (8a, 8c and 8e in FIGS. 3) and thus block the magnetism therein, turning off the detectors. The signals thus generated are sent to a control unit (not shown) to inform that the car 6 has reached the first top operation point. When the car 6 further ascends and the position detectors 8a to 8f reach the second top operation point, the top plates 10a to 10c relatively enter the corresponding position detectors (8a, 8c and 8f in this embodiment), and thus block the magnetism therein, turning off the position detectors. Thereby, the control unit is informed that the car 6 has reached the second top operation point. 
     As the car 6 further ascends, the top plates 11a-11c, 12a-12c and 13a-13c provided at the third, fourth and fifth operation points sequentially pass through the corresponding position detectors (8a, 8d, 8e), (8a, 8d, 8f) and (8a, 8e, 8f), respectively, blocking the magnetism therein, that is, turning off the position detectors. Thus, the control unit receives signals from the position detector unit as the car 6 passes the individual operation points. 
     Because the position detector unit comprising the position detectors 8a to 8e detects the position of the car 6 on the basis of the arrangement of each group of top plates 9a-9c, 10a-10c, 11a-11c, 12a-12c and 13a-13c arranged distinguishably from the other groups, the operation points where the position detector unit performs detection will remain in the same positions despite aging. Further, because the position detectors do not contact the top (or bottom) plates, the association of the position detectors with the plates causes no noise. 
     Position detection is performed in substantially the same manner when the car 6 is near the bottom terminal floor, and will not be described herein. 
     Although this embodiment utilizes magnetic effects, photoelectric effects may be utilized according to the present invention. More specifically, photoelectric detector means may be employed instead. 
     According to the present invention, because an elevator car position detecting apparatus comprises: a plurality of plates provided at each of operation points in such arrangement that one operation point is distinguishable from another operation point; and a position detector which is provided on a car and which is associable with the corresponding plates without contacting the plates and generates a signal indicating that the car has reached one of the operation points when associated with one of the plates, the apparatus achieves accurate and precise detection of the position of an elevator car, facilitates installation, and achieves quiet operation.