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This patent application is a continuation of my U.S. patent application, Ser. No. 781,900 filed Sept. 30, 1985 and now abandoned, for &#34;Hydraulically Operated Elevator Door Mechanism&#34;. 
    
    
     The priot Art: 
     
         ______________________________________Patents           Inventor______________________________________1,530,9641,574,7171,632,5061,751,0581,845,9041,950,1502,579,0173,012,6363,738,4543,194,3453,231,0483,370,6773,535,8373,598,2023,605,9523,702,6453,739,0091,927,580         Wisner2,378,409         Joy2,480,527         Wachter3,327,428         Horton et al  89,252          Siemens (Austrian)  556,487         Hobrough (Canada)1,012,707         Nibaud (France)______________________________________ 
    
     BACKGROUND OF THE INVENTION 
     This invention relates to elevator systems, and in particular to the opening and closing of elevator cab doors using a hydraulic drive unit to move the doors open and closed. 
     In a typical automatic elevation system, there is an automatic drive unit mounted on the cab that opens and closes the cab door. Typically, such system includes a DC motor with an assembly of various mechanical cams, used to operate electrical &#34;slow-down&#34; units. These systems, with many moving parts, are subject to frequent malfunction and are not easily or efficiently repaired. 
     SUMMARY OF THE INVENTION 
     A hydraulically operated elevator door mechanism is proposed having a housing and motor which drives a shaft connected to a first spur gear. A second spur gear meshes with the first spur gear to be turned thereby, the two spar gears situated in a housing chamber and acting as a pump, driving oil through the chamber in a direction which depends on rotation of the shaft. At both ends of the chamber are orifices in the housing, fluidly connecting a cylinder chamber in which a piston is located. Thus, rotation of the shaft in one direction cause oil to be pumpted into one side of the cylinder chamber, increasing pressure on one side of the piston. A corresponding decrease in pressure occurs on the opposite side of the piston, the pressure difference over the piston propelling the piston toward the pressure side. Valve pins are used to control oil flow through the orifices, and thus control piston speed relative to the stationary housing. A cable connects the housing over two pulleys to an elevator door which moves in response to the piston movement. 
     An object of this invention is to provide a means of moving the door using a reversible drive motor, a reversible pump, a movable piston and a 2:1 linkage system. 
     Another object of the invention is to provide a door operating mechanism that have few moving parts, is quickly and efficiently adjusted, and is easily installed. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 shows a hydraulic drive unit mounted on an elevator car top with a drive piston extended, and the door open. 
     FIG. 2 shows a hydraulic drive unit mounted on an elevator car top with a drive piston extended opposite that of FIG. 1, and the door closed. 
     FIG. 3 reveals a top view of the present invention. 
     FIG. 4 portrays a sectional side view of the present invention. 
     FIG. 5 presents a sectional end view of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a housing structure 1 mountcd to a wall surface, the remaining elements of the hydraulically operated door mechanism having been actuated to drive the door 2 left. The shaft like structure 3 comprises the rail which is guided through the housing structure 1 to pull the door 2 in the same direction as the rail 3 moves. 
     FIG. 2 shows the apparatus of the invention, however operated such that the door 2 is positioned to the right. Here, the rail 3 is shown after sliding through the housing structure 1. It is evident that the housing structure 1 is stationary with respect to the sliding door 2 and rail 3, but is merely positioned as such for purposes of illustration. 
     FIG. 3 shows a top view of a hydraulically operated elevator door mechanism, in accordance with the present invention. In addition to the elements of FIGS. 1 and 2, a driving means or motor 4 is shown attached to a wall surface, and having a shaft 5 connected to drive a gear-like means (not shown) located within the housing structure 1. The details of operation of the present invention are better understood with respect to FIGS. 4 and 5 below. Valve pins 6 and 7 may be adjusted from the top side of the housing structure 1, for controlling the flow of fluid (discussed below) within the housing structure 1, such that the open and closing speed of the door may be regulated. 
     FIG. 4 provides a side, sectional view of the mechanism, taken along line 4--4 of FIG. 3. Within the housing structure 1 is a means for containing a fluid 8, comprising orifices 9A and 9B which fluidly connect a reservoir chamber 10 to a cylinder chamber 11. As is evident, the orifices 9A and 9B, the reservoir chamber 10 and the cylinder chamber 11 form a closed loop in which the oil 8 or other hydraulic fluid flows. To the shaft 5 is mounted a spur gear 12 which is rotated in response to any turning of the shaft 5 by the motor 4 (see FIG. 3). A second spur gear 13 is meshed with the spur gear 12 and is driven thereby. Thus, if the shaft 5 is actuated in the clockwise direction, so is the spur gear 12, while the spur gear 13 turns in the counter-clockwise direction. Attached to the rail 3 is a piston and piston ring 14 coaxial with the rail 3. The piston ring 14 divides the cylinder chamber 11 into two portions which vary in size depending upon the position of the piston ring 14. Attached to either end of the rail 3 are pulleys 15. Anchors 16, at the housing structure 1, secure two lengths of cable 17 which extend over the respective pulleys 15 and are connected to the door 2. 
     The operation of the present invention is must easily seen with respect to FIG. 4. Actuation of the motor 4 may turn the shaft 5, and thus the spur gear, in a clockwise direction. Accordingly, the meshed spur gear 13 rotates counter-clockwise, the two spur gears 12, 13 driving fluid left as viewed in FIG. 4. Fluid 8 so forced, flows from the reservoir chamber 10 through the orifice 9A and into the left portion of the cylinder chamber 11. Thus, a high pressure is realized within the cylinder chamber to the left of the piston ring 14, and owing to the closed loop fluid path a corresponding low pressure is created in the cylinder chamber 11 portion which is right of the piston ring 14. The resultant differential pressure occurring across the piston ring 14 propels the piston right, towards the low-pressure side. The rail 3 being connected to the piston, also moves to the right carrying pulleys 15. Since the right cable length 17 is attached to the housing structure 1 at 16 and because the right pulley is moving right, the portion of the cable length 17 between the right pulley 15 and the door 2 &#34;shortens&#34;, in a manner which causes the door 2 to slide right. In effect the cable pulls the door. Thus, for every inch of piston 14/rail 4 travel, the door travels two inches. It is readily apparent that turning the shaft 5 counter-clockwise will move the door left. 
     Also visible in FIG. 4 are threaded holes for reception of the valve pins 6 and 7. Turning of the valve pins 6, 7 into the threaded holes will close off any of the desired orifices 9A, 9B. Thus, the flow of fluid within the closed loop is regulated by adjusting the valve pins 6, 7 to an appropriate depth, which in turn regulates the speed at which the door opens and closes. Evident also, in the housing structure 1 where the rail 3 exits, are two sealing members which prevent leakage of the fluid 8 from the cylinder chamber 11. 
     FIG. 5 shows a sectional end view of the invention, wherein the piston ring 14 is shown closing off the cylinder chamber 11 into a front portion (the rear portion is not visible). Here, the coaxially relationship of the piston ring 14 and rail 3 are easily seen. The shaft 5 is directly coupled to the spur gear 12 to spin upon its associated bearing. The meshed spur gear 13 rotates freely upon its associated bearing, but being meshed with the spur gear 12 is driven in a direction opposite that of the rotating spur gear 12. 
     Modifications to the present invention are apparent to those skilled in the art, which do not depart from the spirit of the present invention, the scope being defined by the appended claims.

Summary:
A hydraulically operated elevator door mechanism includes a motor-driven shaft connected to rotate gears within a fluid reservoir. Fluid is &#34;pumped&#34; as the gears rotate, to one side of a piston, propelling the piston. The piston is connected to two pulleys over which a cable length is attached to the elevator door. Piston movement causes the pulleys to effectively shorten the length of cable between the pulley and door, which in turn, causes the door to slide.