Abstract:
A power mine door installation utilizing compressed air from the compressed air system available in the mine as the power source for a hydraulic door-operating mechanism.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to a mine door installation, and more particularly to a power-operated mine door system installed in a passageway in a mine.  
           [0002]    The invention is especially concerned with a mine door system wherein doors for a passageway in a mine are adapted for powered opening and closing by means of hydraulic instrumentalities (specifically hydraulic cylinders).  
         SUMMARY OF THE INVENTION  
         [0003]    Among the several objects of the invention may be noted the provision of a mine door system having a door-operating hydraulic instrumentality (such as a hydraulic cylinder) for a door thereof (or two such instrumentalities for a pair of doors) which is safely operable in a dangerous environment down in a mine (e.g. in a passageway where there may be explosive gas); the provision of a system such as described which eliminates the need for electrical empowerment (e.g. eliminates the need for an electric motor) and thus avoids arcing and sparking which might set off an explosion; the provision of such a system taking advantage of a power source in the mine for other purposes; and the provision of such a system which is relatively economical to install and reliable in operation.  
           [0004]    The invention takes advantage of the compressed air system conventionally available in a mine, generally comprising the provision of an air motor for driving a pump for supplying hydraulic fluid under pressure to a hydraulic instrumentality for operating a door in the mine, and a compressed air circuit for supplying the air motor with compressed air from said compressed air system in the mine.  
           [0005]    Other objects and features will be in part apparent and in part pointed out hereinafter. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is a top plan view of a double-door mine door arrangement having a hydraulic cylinder for operating each of the door components; and  
         [0007]    [0007]FIG. 2 is a diagram showing hydraulic and air circuitry of the invention for operating the door components.  
     
    
     DETAILED DESCRIPTION  
       [0008]    [0008]FIG. 1 shows a power mine door installation, generally designated  1 , for a doorway in a mine comprising a door frame generally indicated at  3  having a pair of door components  5  and  7  (each a generally rectangular door leaf) hinged on the frame as indicated at  9  and  11  at opposite sides of the doorway for swinging movement between open and closed positions. The door leafs are shown in open position in FIG. 1; in closed position they are generally coplanar. Leafs  5  and  7  are swingable between their open and closed positions by means of hydraulic instrumentalities. In one embodiment, these instrumentalities comprise hydraulic cylinders  15  (for leaf  5 ) and  17  (for leaf  7 ), each pivoted at its head end  19  on the frame  3  as indicated at  21  and having its piston rod  23  extending from its piston  25  (see FIG. 2) to a pin connection  27  with the respective leaf.  
         [0009]    Now referring to FIG. 2, the power mine door installation  1  is shown to include a pumping unit  29  comprising a pneumatically driven pump  31  for supplying hydraulic fluid under pressure to the hydraulic cylinders  15 ,  17  for operation thereof to operate the respective door leafs  5 ,  7  via a four-way valve  33  which can be operated manually or by any other suitable means (e.g., solenoid, pilot, motor). Unit  29  further comprises an air motor  35  for driving pump  31 . At  37  is generally indicated a compressed air circuit for supplying air motor  35  with compressed air from a compressed air system  39  in the mine, said circuit including an on-off valve  41  therein. System  39  is preferably one conventionally available in a mine for supplying compressed air generally for mine-related purposes as will be readily understood. Alternatively, the system  39  could be a dedicated system provided for the sole purpose of supplying air under pressure to air motor  35 .  
         [0010]    The pump  31  is adapted to receive hydraulic fluid via line  43  including a filter  45  from a supply at  47  and deliver it under pressure to the inlet of valve  33  via a line  49 , with a pressure relief line  51  extending from line  49  including a pressure relief valve  53 . At  55  is indicated in phantom an interconnection between valve  41  and valve  33  for synchronization of operation thereof such that the air valve  41  is opened to start the air motor  35  at substantially the same time as the valve  33  is actuated to either the “open door” or “close door” position. In a first setting of valve  33 , it is adapted to deliver hydraulic fluid under pressure via line  57  including a quick-connect coupler  59  and branch lines  61  and  63  including flow controls designated  65  and  66 , respectively, to the head ends of cylinders  15 ,  17  and vents the rod ends of the cylinders via branch lines  67  and  69 , line  71 , quick-connect  73  and valve  33  to tank  74 . In a second setting of the valve  33 , it delivers hydraulic fluid under pressure via  71 ,  67 , and  69  to the rod ends of the cylinders and vents the head ends of the cylinders via  61 ,  63 ,  59 ,  57  and valve  33  to tank  74 . Lines  57  and  71  are connected to sumps  75  and  77  via lines  79  and  81  including release valves  83  and  85 , respectively. In the case of malfunction or a loss of power, these release valves may be opened manually to depressurize the system and allow the door components  5 ,  7  to be operated (opened and/or closed) by hand.  
         [0011]    It will be apparent from the above that with the pump  31  in operation and valve  33  in its first setting, the piston rods  27  will be extended to open the door components (leafs)  5  and  7 , and that with the pump  3  in operation and valve  33  in its second setting, the piston rods will be retracted to close the door components. The operation of the pump  31  by the air motor  35 , which is economically effected because the compressed air system  39  is already there in the mine, avoids the danger (such as may be caused by use of an electric motor and associated equipment) of explosion in the event of presence of explosive gas.  
         [0012]    In one embodiment, each flow control  65 ,  66  includes a check valve  65 CV,  66 CV and a fluid restricting (e.g., needle) valve  65 RV,  66 RV for restricting the flow of fluid. In the first setting of the valve  33 , the check valves  65 CV,  66 CV open to allow full flow of hydraulic fluid under pressure to the cylinders  15 ,  17  to open the doors leafs. In the second setting of the valve  33 , the check valves  65 CV,  66 CV close and the hydraulic fluid flows through the restricting valves  65 RV,  66 RV to control the closing speed of the door leafs (i.e., to prevent door runaway). The restricting valves  65 RV,  66 RV can also be used to control the closing sequence of the door components  5 ,  7 . For example, if one of the components is a door leaf carrying an astragal sealing flap, the restricting valves can be configured so that the door leaf with the flap closes last to ensure proper sealing of the flap against the other door leaf.  
         [0013]    Means other than on-off valve  41  may be used to synchronize the operation of the air circuit  37  and the hydraulic fluid valve  33 . Indeed, this valve may be eliminated altogether, in which case the required synchronization can be effected simply by turning the air motor  35  on and off, for example.  
         [0014]    In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.  
         [0015]    As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.  
         [0016]    When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.