Patent Publication Number: US-9416658-B2

Title: Fluid tank balancing system for mining machine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of prior-filed, co-pending U.S. Provisional Application Ser. No. 61/929,749, filed Jan. 21, 2014, the entire contents of which is hereby incorporated by reference. 
    
    
     BACKGROUND 
     The present invention relates to the field of mining machines. Specifically, the present invention relates to a fluid balancing system for a mobile mining machine. 
     Conventional longwall shearers include a frame and a pair of cutting assemblies mounted on each end of the frame. Each cutting assembly includes a cutting drum for engaging a mine wall. As the frame traverses a mine frame, the cutting drums cut material from the mine face. In some embodiments, the material is deposited on a conveyor and carried away from the mine face. The floor of the mine may be uneven, and therefore it is possible for the frame to be inclined or positioned on a slope as it travels back and forth relative to the mine face. 
     SUMMARY 
     In one aspect, the mining machine includes a frame, a first fluid tank, a second fluid tank, a valve, and a control system. The frame includes a first end and a second end and at least one cutting assembly. The first fluid tank is supported on the frame proximate the first end. The second fluid tank is supported on the frame proximate the second end. The valve is movable between a first position and a second position. The valve permits fluid communication between the first fluid tank and the second fluid tank when the valve is in the first position. The valve prevents fluid communication between the first fluid tank and the second fluid tank when the valve is in the second position. The control system includes a first sensor, a second sensor, and a controller. The first sensor detects an amount of fluid in the first fluid tank, and the second sensor detects an amount of fluid in the second fluid tank. The controller moves the valve to the first position when the difference between the amount of fluid in the first fluid tank and the amount of fluid in the second fluid tank exceeds a predetermined threshold. 
     In another embodiment, a fluid balancing system balances the amount of fluid in at least two fluid tanks supported on a mobile mining machine. The fluid balancing system includes a valve, a first sensor, a second sensor, and a controller. The valve is movable between a first position and a second position. The valve is configured to permit fluid communication between the fluid tanks when the valve is in the first position, and the valve configured to prevent fluid communication between the fluid tanks when the valve is in the second position. The first sensor is configured to generate a first signal indicative of an amount of fluid in a first fluid tank. The second sensor is configured to generate a second signal indicative of an amount of fluid in a second fluid tank. The controller compares the first signal and the second signal and calculates a difference between the amount of fluid in the first tank and the amount of fluid in the second tank. The controller moves the valve to the first position when the difference exceeds a predetermined threshold. 
     In yet another embodiment, a method of balancing fluid levels between a first tank and a second tank supported on a mobile mining machine includes: providing a valve movable between a first position and a second position such that the valve permits fluid communication between the first tank and the second tank when the valve is in the first position, and the valve prevents fluid communication between the first tank and the second tank when the valve is in the second position; generating a first signal indicative of an amount of fluid contained in the first tank; generating a second signal indicative of an amount of fluid contained in the second tank; comparing the first signal and the second signal to calculate a difference between the amount of fluid in the first tank and the amount of fluid in the second tank; comparing the calculated difference against a predetermined threshold; and when the calculated difference exceeds the predetermined threshold, moving the valve to the first position to permit fluid communication between the first tank and the second tank. 
     Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a mining machine. 
         FIG. 2  is a rear perspective view of a portion of the mining machine of  FIG. 1  and a mine face. 
         FIG. 3  is a rear end view of the mining machine of  FIG. 1  and a mine face. 
         FIG. 4  is a schematic view of a fluid balancing system. 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of the configuration and arrangement of components set forth in the following description or illustrated in the accompanying drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. 
     In addition, it should be understood that embodiments of the invention may include hardware, software, and electronic components or modules that, for purposes of discussion, may be illustrated and described as if the majority of the components were implemented solely in hardware. However, one of ordinary skill in the art, and based on a reading of this detailed description, would recognize that, in at least one embodiment, the electronic based aspects of the invention may be implemented in software (e.g., stored on non-transitory computer-readable medium) executable by one or more processing units, such as a microprocessor and/or application specific integrated circuits (“ASICs”). As such, it should be noted that a plurality of hardware and software based devices, as well as a plurality of different structural components may be utilized to implement the invention. For example, “servers” and “computing devices” described in the specification can include one or more processing units, one or more computer-readable medium modules, one or more input/output interfaces, and various connections (e.g., a system bus) connecting the components. 
       FIG. 1  illustrates a mining machine, such as a longwall shearer  10 , including a chassis or frame  14  and a pair of cutting assemblies  18 . The frame  14  includes a first end  20 , a second end  22 , and a body axis  24  extending between the first end  20  and the second end  22 . A first cutting assembly  18   a  is coupled to the first end  20  of the frame  14  and a second cutting assembly  18   b  is coupled to the second end  22 . 
     Each cutting assembly  18  includes a ranging arm  26  and a cutting drum  30 . The ranging arm  26  is pivotably coupled to the frame  14  and rotatably supports the cutting drum  30 . Each drum  30  is coupled to an end of a ranging arm  26  and is rotatable about a drum axis  46  that is generally perpendicular to the ranging arm  26 . The cutting drum  30  includes a generally cylindrical body having vanes  38  and cutting bits  42  positioned along the front end of the drum  30  and along the edges of the vanes  38 . In the illustrated embodiment, the vanes  38  extend in a spiral or helical manner along the periphery of the drum body. In some embodiments, the cutting assembly  18  may also include a guide for deflecting cut material toward a material handling mechanism, e.g., a face conveyor  48  ( FIG. 3 ). 
     As shown in  FIGS. 2 and 3 , the frame  14  is configured to tram or move along a wall of material to be mined or mine face  50  in a first direction  54  and a second direction  58 . In the illustrated embodiment, the frame  14  includes a drive sprocket assembly  60  that engages a rack  62  to form a rack-and-pinion connection. The rack  62  is coupled to the face conveyor  48  and advances toward the mine face  50  as the frame  14  completes a predetermined number of passes along the face  50 . The rotation of the drive sprocket assembly  60  drives the frame  14  along the rack  62 . 
     Referring to  FIG. 2 , each drum  30  is configured to engage the mine face  50  such that the bits  42  cut material from the face  50 . As the cutting drum  30  rotates, the vanes  38  carry the cut material from the face  50  toward a rear end of the drum  30 , where the cut material is deposited onto the face conveyor  48  below the frame  14 . As the frame  14  moves in the first direction  54 , the first cutting assembly  18   a  is in a leading position and the second cutting assembly  18   b  ( FIG. 3 ) is in a trailing position. In one embodiment, the first cutting assembly  18   a  is elevated to cut material, such as coal, from an upper portion of the mine face  50 , while the second cutting assembly  18   b  is in a lower position to cut material from a lower portion of the mine face  50 . 
     In one embodiment, each cutting assembly  18  is hydraulically driven and the frame  14  supports a pair of fluid tanks  64  ( FIG. 2 ) for providing pressurized fluid to drive the cutting assemblies  18 . In the illustrated embodiment, a first fluid tank  64   a  is positioned proximate the first end  20  of the frame  14  and a second fluid tank  64   b  is positioned proximate the second end  22  of the frame  14 . In some mines, the mine face  50  is inclined laterally. As a result, as the frame  14  moves from one side of the mine face  50  to the other, the frame  14  may be oriented on an incline such that the body axis  24  of the frame  14  forms a lateral angle  66  relative to a horizontal plane  68  during at least a portion of the movement. 
       FIG. 4  illustrates a control system  70  for balancing fluid levels between the first tank  64   a  and the second tank  64   b.  The system  70  includes a main controller  86 , a frame angle sensor  90 , a first sensor  94 , a second sensor  98 , and a valve  102  in fluid communication with the first tank  64   a  and the second tank  64   b.  In the illustrated embodiment, the valve  102  is an electrically-operated valve (e.g., a solenoid valve). In other embodiments, other types of valves may be used. 
     The frame angle sensor  90  detects the roll angle of the frame  14 , or the angle  66  ( FIG. 3 ) of the body axis  24  of the frame  14  relative to the level plane  68  ( FIG. 3 ). The frame angle sensor  90  generates a signal representing the measured frame angle  66  and transmits the signal to the main controller  86 . The first sensor  94  detects an amount of fluid in the first tank  64   a,  and the second sensor  98  detects an amount of fluid in the second tank  64   b.  In one embodiment, the sensors  94 ,  98  are analog fluid level sensors. The sensors  94 ,  98  may measure the height of fluid contained in each fluid tank  64   a,    64   b.  Each sensor  94 ,  98  generates a signal representing the detected amount of fluid in their respective tanks  64   a,    64   b  and transmits the signal to the main controller  86 . In some embodiments, each signal from the sensors  94 ,  98  represents a ratio or percentage of the respective tank  64   a,    64   b  that filled with fluid. The main controller  86  compares the signals generated by each sensor  94 ,  98 . 
     In one embodiment, when the sensed amount of fluid in either tank  64   a,    64   b  is below a predetermined level, the main controller  86  generates an alarm and disables a fluid pump (not shown) operating the cutting assembly  18   a,    18   b  associated with the tank  64   a,    64   b  that is low. In some embodiments, the predetermined level is defined or set by a user depending on a variety of factors. The controller  86  confirms that the angle  66  detected by the frame angle sensor  90  is within an acceptable range and, if so, a human-machine interface (HMI) display screen  110  ( FIG. 4 ) prompts a machine operator to initiate a “Tank Level Balance” function. If the frame angle  66  is not within a permitted range, the main controller  86  does not permit the valve  102  to be opened. In one embodiment, the permitted range for the frame angle  66  is less than or equal to 20 degrees relative to a horizontal plane. Due to various factors, the permitted range of the frame angle  66  may not be symmetric relative to the horizontal plane; that is, the negative limit may be different from the positive limit of the permitted range. In some embodiments, the main controller  86  includes a comparator comparing the difference between the amount of fluid in each fluid tank  64 , and the main controller  86  generates an alarm if the difference exceeds a predetermined threshold. In some embodiments, the main controller  86  automatically actuates the valve  102  when the difference exceeds the predetermined threshold and the frame angle  66  is within the permitted range. 
     If the angle  66  detected by the frame angle sensor  90  is within an acceptable range, the main controller  86  moves the valve  102  to an open position to permit fluid flow between the tanks  64   a,    64   b.  The valve  102  remains open until the fluid levels detected by each sensor  94 ,  98  are substantially equal to one another (i.e., the difference between the fluid level of the first tank  64   a  and the fluid level of the second tank  64   b  is less than a predetermined amount). When this condition is satisfied, the main controller  86  de-energizes the valve  102 , moving it to a closed position to prevent flow between the tanks  64   a,    64   b.    
     During a mining operation, fluid may be depleted in one of the tanks  64   a,    64   b  while the machine  10  is located in a position that is difficult to access and away from a fluid supply (e.g., the far extreme of the mine face  50 ). On a conventional mining machine, this requires an operator to carry containers of fluid to the machine and refill the tank that is depleted, which is time-consuming and cumbersome. The control system  70  permits fluid to flow from one tank to the other in the event that the fluid in a single tank has become low, thereby transferring fluid from a full (or partially full) tank to a depleted or low tank without requiring a machine operator to manually fill the low tank to a desired level. 
     Balancing the tanks  64  allows the machine  10  to continue operation at least until the machine  10  is positioned in an area of the mine that facilitates servicing the machine  10  (e.g., close to a supply of fluid for re-filling the tanks  64 ). In addition, in a maintenance situation when one or both tanks  64  are low on fluid, an operator can fill one of the tanks  64  and utilize the fluid level balancing sequence to transfer the fluid to the other tank. By only filling one of the tanks  64 , the operator reduces maintenance time and reduces the possibility that debris in the mine environment and around a tank port (not shown) will enter the port and contaminate the fluid. Furthermore, by sensing the lateral angle  66  of the machine frame  14 , the control system  70  prevents the valve  102  from being opened when the machine  10  is positioned on an incline ( FIG. 3 ) that would inhibit fluid flow between the tanks  64  or that would make it difficult to fill the tanks  64  equally. 
     Thus, the invention provides, among other things, a fluid tank balancing system for a mobile mining machine. Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention as described.