Abstract:
System and method for controlling a moving floor having multiple sliding slats, to produce a practically continuous load-moving force on a load carried on the apparatus. The slats are reciprocated back and forth by hydraulic cylinders, each of which controls a group of slats that are moved together. At any given time, a majority of the slats are moving together in the desired direction, and carry a load in this direction at a nearly uniform velocity. The remainder of the slats are moved in a reverse direction at the same time. The movement of the slats is controlled by an infinite piston positioning feedback system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. §119(e) to Provisional Application No. 61/785,630, filed Mar. 14, 2013, which application is hereby incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     A. Technical Field 
     This invention relates generally to techniques for moving a heavy load continuously by moving a supporting floor beneath the load and, more particularly, to techniques for moving a heavy load supported on a floor consisting of multiple movable slats. If, for example, all of the slats are moved together in one direction, the load will be carried in that direction, but if the slats are returned to their starting positions in smaller groups simultaneously containing only a fraction of the total number of slats, then the frictional forces between the load and a returning group of slats will be insufficient to move the load in the reverse direction. This invention relates specifically to the infinite control of the movement of the slats to achieve desired results in movement of the load. 
     B. Background of the Invention 
     Moving floors of this type have a number of useful applications, one of which is in the collection and disposal of garbage or waste. In large cities, long distances to disposal sites have resulted in the increased use of large transfer trailers, for the temporary storage of waste gathered by collection vehicles. When a transfer trailer is full, it is towed to a disposal site for emptying. Emptying such a vehicle by tipping is cumbersome and difficult if a large trailer is used, movable floors provide an ideal solution. Typically, a rear door of the trailer is opened and the waste material is ejected through the door by operation of the moving floor. 
     Another useful application of a moving floor of this type is in a warehouse setting where large loads, including loads on pallets, need to be moved or moved and loaded onto trucks or between trucks. Currently a forklift is used in a warehouse setting to move large pallet loads or load pallets onto a truck or between trucks. 
     Systems in use prior to the present invention are sometimes referred to as “walking” floors and operate by moving all of the slats in the desired direction as far as they can travel, and then returning each slat one group at a time. These systems incorporate relatively simple hydraulic control techniques and, when a hydraulic cylinder reaches the limit of its travel, the fluid flow from a hydraulic pump must be bypassed to a holding tank until valves can switch the cylinder in the appropriate direction. Furthermore, the load cannot move forward continuously, but either has to stop or move backward for part of the time. 
     The principal disadvantage of prior systems of this general type is that the load movement is started and stopped repeatedly, which is clearly inefficient and time consuming. Palletized loads cannot be effectively moved using prior systems due to the large amount of skew that occurs as a result of the starting and stopping of the load and the high percent of returning slats. The time to unload is at least twice as long as it would be if the load could move continuously. In addition there are hydraulic control system disadvantages, in that the oil tends to overheat due to the need for bypassing the pump at the end of all of the strokes before the hydraulic cylinders can switch. Moreover, rather large pump flow rates are required to gain reasonable speeds. The present invention overcomes all of these disadvantages. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention overcome the disadvantages of the prior art moving floor systems by allowing the load to move forward continuously and without skew as experienced by prior art systems. Embodiments of the present invention reside in a moving floor than can move a load at the maximum possible speed, at the lowest cost and without any overheating of the oil in the system during prolonged operation. Embodiments of the invention accomplish these goals by combining a hydraulic subsystem, including hydraulic cylinders, a pump, and control valves, with infinite piston position sensors, and an electronic control unit. The hydraulic subsystem accomplishes the desired objectives by operating a moving floor in which a majority of the slats are always moving in the desired direction of load movement. The position sensors sense the position of the pistons relative to each other. The electronic control unit uses an infinite piston positioning feedback to control the movement of the hydraulic cylinders. 
     Embodiments of the present invention include a plurality of elongated floor slats movable in a direction parallel to the slats, and a hydraulic system for moving the slats in a reciprocating manner such that, at any instant during operation of the system, a majority of the slats are moving in the desired direction at a predetermined speed, and a minority of the slats are moving in the opposite direction at a higher speed, for example three times the speed. The load supported by the floor will tend to move in the direction of the majority of slower moving slats at all times when the floor is operating. 
     A plurality of hydraulic cylinder infinite piston position sensors provide electronic feedback to the electronic control unit, which commands the electronic proportional valves that accelerate, decelerate, and control varying oil flow rates that cause all four hydraulic cylinders to function independently to provide a continuous moving floor. Three staggered stroke hydraulic cylinders propel the payload at all times while one hydraulic cylinder is retracting and as each hydraulic cylinder reaches maximum extension, it retracts and the previously retracted cylinder extends to join the other two extending hydraulic cylinders. 
     Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments. 
         FIG. 1  shows a functional block, in accordance with various aspects of the present invention. 
         FIG. 2  shows a flowchart, in accordance with various aspects of the present invention. 
         FIG. 3  shows a top view of mechanical, hydraulic and electronic components, in accordance with various aspects of the present invention. 
         FIG. 4  shows a cross sectional view of an infinite piston position sensor, in accordance with various aspects of the present invention. 
         FIGS. 5A and 5B  shows a top view of mechanical, hydraulic and electronic components for a twenty slat system, in accordance with various aspects of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description is set forth for purpose of explanation in order to provide an understanding of the invention. However, it is apparent that one skilled in the art will recognize that embodiments of the present invention, some of which are described below, may be incorporated into a number of different computing systems and devices. The embodiments of the present invention may be present in hardware, software or firmware. Structures shown below in the diagram are illustrative of exemplary embodiments of the invention and are meant to avoid obscuring the invention. Furthermore, connections between components within the figures are not intended to be limited to direct connections. Rather, data between these components may be modified, re-formatted or otherwise changed by intermediary components. 
     Reference in the specification to “one embodiment”, “in one embodiment” or “an embodiment” etc. means that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. 
       FIG. 1  shows a functional block, in accordance with various aspects of the present invention. As described in U.S. Pat. No. 4,739,463 issued Dec. 27, 1988 and entitled “Multiphase Sliding Floor For Continuous Material Movement” (“the &#39;468 patent”) and incorporated herein by reference, a load is moved on a movable floor in a practically continuous manner, since the majority of the slats are always moving in a desired direction. This continuity of operation provides a much more efficient and rapid load movement and also results in a more efficient hydraulic subsystem design. 
     In an embodiment of the present invention, a four slat moving floor system is used. In a four slat moving floor system, three of the four slats are moving in the desired direction and only one slat is moving in the direction opposite the desired direction. Therefore, the load being moved by the moving floor system is continuously moving in the desired direction. The slats are moved using hydraulic cylinders containing pistons. The present invention uses infinite piston positioning feedback to control the movement of the pistons and, therefore, the movement of the slats in the system. 
     As shown in  FIG. 1 , movable floor  100  comprises a number of slats  110 . The slats  110  are movable and are mounted for movement in a desired direction (forward) and a direction opposite the desired direction (backward). For purpose of illustration a four slat moving floor example is used. However, it will be understood by one of ordinary skill in the art that the system could comprise practically any number of slats. 
     In one embodiment, each slat  110  is mounted on a cross driver  120  for mechanical support. However, the cross drivers  120  are heavy and are mounted with large screws that can cause mechanical problems. Therefore, in one embodiment, the cross drivers  120  are not used. 
     The slats  110  are mechanically coupled to a hydraulic cylinder system  130 . The hydraulic cylinder system  130  can comprise a plurality of hydraulic cylinders. Each hydraulic cylinder gets its power from pressurized hydraulic fluid. In one embodiment, the hydraulic fluid is oil. The hydraulic cylinder comprises a cylinder barrel housing a piston mechanically coupled to a piston rod. The barrel is closed on one end by the cylinder bottom (sometimes referred to as a cap) and the other end by the cylinder head (sometimes referred to as a gland) where the piston rod comes out of the cylinder. The piston divides the inside of the cylinder into two chambers, the bottom chamber (base end) and the piston rod side chamber (rod end). The hydraulic system also has a pump, which brings the fluid into the cylinder and a series of valves that control the flow of the fluid into the cylinder. 
     In one embodiment each slat is mechanically coupled to a hydraulic cylinder in the hydraulic cylinder system  130 . In another embodiment, more than one slat is mechanically coupled to a hydraulic cylinder in the hydraulic cylinder system  130 . 
     In one embodiment, each of the hydraulic cylinders incorporates an infinite piston position sensor  140 . The piston position sensor  140  senses the position of a piston or the piston rod. Since the hydraulic cylinder system  130  contains a plurality of pistons, each piston has a piston position sensor  140 . Therefore, the position of each piston can be determined and known relative to each other piston in the system. 
     The position of the pistons as sensed by the piston position sensors  140  is input into electronic control unit  150 . Electronic control unit  150  is a control unit that uses infinite piston positioning feedback to control the position of each piston in the moving floor system  100 . Based on information collected from the piston positioning sensors  140  and fed into the electronic control unit  150 , the electronic control unit  150  sends signals to proportional valves  170 . Proportional valves  170  can proportionally open and close to let control the flow of fluid to the cylinder. 
     In one embodiment, the electronic control unit  150  is electrically coupled to antenna  160 . Antenna  160  permits remote operation of the moving floor. It will be understood by one of ordinary skill in the art that remote operation can be accomplished using a remote control of any sort including a smart phone, tablet, laptop, personal computer, automobile, truck, or any other type of control device. 
       FIG. 2  shows a flowchart, in accordance with various aspects of the present invention.  FIG. 2  describes the process used in moving the moving floor system of  FIG. 1 . A majority of the slats are moved in the desired direction  210 . A minority of the slats are moved in the opposite direction of the desired direction  220 . For example, in the case of a four slat system, three slats are always moving forward while one slat is simultaneously moving backward. The control system of the present invention controls when the slats are moving forward and when it is moving backward. 
       FIG. 2  also shows sensing the position of the pistons that is used to move the slats  230 . The position of the pistons is input into the electronic control unit  240 . The movement of the pistons is determined based on the electronic control unit  250 . The proportional valves are adjusted based on the position of the pistons  260 . 
       FIG. 3  shows a top view of mechanical, hydraulic and electronic components, in accordance with various aspects of the present invention.  FIG. 3  depicts a monoblock assembly  364 . In one embodiment, the monoblock assembly  364  is made from an aluminum material. In one embodiment, the monoblock assembly  364  is a machined electroless nickel plated aluminum block that has roller burnished hydraulic cylinder bores and internal machined passages that eliminate fittings, hoses, hydraulic tubing, and tie rods. In one embodiment, a leakproof cover can be provided for the protection of the control valves, piston position sensors, antenna, and electronic control unit. In one embodiment, hydraulic pressure and return connections are SAE and o-ring flange type. 
     In the example shown in  FIG. 3 , the monoblock assembly  364  houses four cylinders  316 ,  318 ,  320 , and  322 . Each cylinder also contains a piston position sensor  324 ,  326 ,  328 , and  330 . In one embodiment, piston position sensors  324 ,  326 ,  328 , and  330  sense movement of the rod as it extends and retracts. Piston position sensors  324 ,  326 ,  328 , and  330  can operate in any manner such that the position of the piston is sensed. However, in one embodiment, piston position sensors  324 ,  326 ,  328 , and  330  detect movement of the rod and vary a voltage accordingly. Therefore, any position can be detected and it can be detected continuously. 
     The ability to sense piston position at any point in time and position of the piston overcomes disadvantages of the prior art systems that can only sense the position of the piston at the end of a stroke. A typical position sensor for sensing only the end of stroke uses a poppet type device that is literally contacted by the piston as it extends and causes a valve to open and retracts the cylinder. The present invention overcomes disadvantages of using this poppet typed device by using the piston position sensor and can reduce shock tremendously. 
     In embodiment, within monoblock assembly  364  proportional valves  336 ,  338 ,  340 ,  342 ,  344 ,  346 ,  348 , and  350  can adjust the flow of fluid into the cylinder in an analog fashion. The proportional valves allow the acceleration and deceleration of the pistons to be shaped such that they are smooth and therefore reduce shock. In one embodiment the proportional valves  336 ,  338 ,  340 ,  342 ,  344 ,  346 ,  348 , and  350  are implemented using hydraulically controlled screw in cartridge valves that screw into the monoblock assembly  364 . In one embodiment, proportional valves are solenoid operated directional valves to control the flow of oil to the cylinder. Any type of valve that can adequately control the flow of fluid into the cylinders can be used with the present invention. In one embodiment the fluid used is oil. 
     Valves  356  and  362  are high pressure and low pressure relief valves. Valves  358 , and  360  are two way valves. Valve  384  can be a three way valve. Line  380  is a line showing the pressurized oil. Line  382  is a line showing returning oil back. As described in the &#39;468 patent, the hydraulic system operates using a tank (not shown), a pump, (not shown), and a sequence of valves to control the flow of oil between the tank and the cylinders. 
     In one embodiment of the present invention, the moving floor system uses a regenerative system. In a regenerative system, rather than collecting oil into a tank when the cylinder extends, the oil removed from rod end is reused to be put back into the system at the base end and causes retracting cylinder to retract. An advantage of using a regenerative system on a moving floor is that pump volume can be reduced. 
     Due to the force of regenerative systems, there are occasions when the force is too low, for example when the floor is iced over. The floor can be installed on a trailer that can be kept outside and is subject to weather conditions of the outdoors, including freezing and icing. When the floor becomes iced over, a higher pressure can be needed to break the ice. Therefore, the moving floor system allows for use of a high pressure mode when necessary. Thus, the high pressure mode enables ice to be broken from the moving floor system. Once the ice is broken and the floor is moving, the moving floor system can switch back to the regenerative system. 
       FIG. 3  also shows cylinders  316 ,  318 ,  320  and  322  are mechanically coupled to four cross drivers  304 ,  306 ,  308 , and  310 . Cross drivers  304 ,  306 ,  308 , and  310  are linked to the rods of cylinders  316 ,  318 ,  320  and  322  at connection points  372 ,  374 ,  376 , and  378 . Internal locking elements (not shown) can be used to lock the cross drivers  304 ,  306 ,  308 , and  310  to the hydraulic cylinder rods, thus simplifying installation of the floor. Internal locking elements are wedge shaped tapered devices that slide onto the rod locking it in place. Slats (not shown) are mechanically coupled to cross drivers  304 ,  306 ,  308 , and  310  at yokes  370 . In one embodiment yokes  370  can be made of polyurethane lined aluminum. The slats can be mounted perpendicular to the cross drivers  304 ,  306 ,  308 , and  310  and move in the same direction as the pistons. 
     In the embodiment shown in  FIG. 3 , twenty slats can be connected to the four cross drivers  304 ,  306 ,  308 , and  310 . In the embodiment shown five slats can be connected to each cross driver  304 ,  306 ,  308 , and  310  resulting in each cylinder  316 ,  318 ,  320  and  322  moving five slats. As described above, each cylinder  304 ,  306 ,  308 , and  310  will move the slats forward for part of the time and backward for part of the time, but with three cylinders moving slats forward and one cylinder moving slats backward. 
       FIG. 3  also shows bearing support  302 , a mechanical structure used to support the rods when fully extended. The bearing support  302  is mechanically coupled to the rods at connection points  312 . 
       FIG. 3  also shows an integrated hydraulics manifold  368 . Integrated hydraulics manifold  368  houses the electronic control unit  332  and antenna  352 . Antenna  352  permits control of the moving floor by remote control  386  as described with reference to  FIG. 1 . The integrated hydraulic manifold  368  can be physically mounted on the monoblock assembly  364  or it can be located separately. Electronic control unit  332  takes as input the positions of all the pistons in the system and the relative positions of the pistons and configures the control of the pistons such that the slats move in a desired fashion. The piston position sensors  324 ,  326 ,  328 , and  330  are electrically coupled to the electronic control unit  332  by way of electrical connection  334 . Electrical connection  334  can be a wired connection or a wireless connection using any available wired or wireless technologies. 
     For the purposes of simplicity of explanation, a four cylinder, four slat system will be described. However, one of ordinary skill in the art will appreciate that any number of cylinders and slats can be implemented. For ease of discussion, the four pistons will be referred to as P 1 , P 2 , P 3 , and P 4 . For example, based on the positions of the pistons, electronic control unit  332  can actuate P 1  when it travels two inches, actuate P 2 , when P 2  travels 2 inches, actuate P 3  and retract P 4 . When P 1  reaches the end, it reverses and P 4  is actuated forward. It will be understood by those of skill in the art that any appropriate distance can be used other than two inches. 
     Using the combination of the piston position sensors  324 ,  326 ,  328 , and  330 , the electronic control unit  332 , and the proportional valves  336 ,  338 ,  340 ,  342 ,  344 ,  346 ,  348 , and  350  permits the infinite feedback control system to operate. Using the infinite feedback control system has the advantages of moving the load faster and keeping it continuously moving, uses less horsepower, less fuel, lower pressure, less heat, and has less wear and tear than a traditional system. 
       FIG. 4  shows a cross sectional view of a monoblock assembly  410  including an infinite piston position sensor  405 , in accordance with various aspects of the present invention.  FIG. 4  shows the piston position sensor  405  within the piston rod  430 . In one embodiment, the piston position sensor is actually inserted in the rod as shown in  FIG. 4 . However, it will be understood that any infinite piston position sensor can be used. In one embodiment, a quarter inch diameter sensor is inserted into a hole in the piston rod and voltage changes to indicate position. The piston position sensor can sense very small changes in position. For example, for a six inch stroke, the piston position sensor can sense any change throughout the full stroke. 
       FIG. 4  also shows piston  415  mechanically coupled to piston rod  430 .  FIG. 4  also shows bearings  420 , seals  425 , and rod gland  435  that operate in conjunction with piston  415  in the hydraulic system to move the piston and seal the piston such to form a seal between one chamber of the cylinder and the other. 
       FIGS. 5A and 5B  show a top view of mechanical, hydraulic and electronic components for a twenty slat system, in accordance with various aspects of the present invention.  FIG. 5A  shows part of the view and  FIG. 5B  shows the other part. The view was split between two figures for ease of capturing the view within the constraints of the size of the page.  FIG. 5A  continues in  FIG. 5B  as indicated in the figures.  FIGS. 5A and 5B  are similar to  FIG. 3  in that they show cylinders  544 , proportional valves  552 , and piston position sensors  542  within monoblock assembly  556 , and integrated hydraulics manifold  558  housing electronic control unit  554  and antenna  560 . Both  FIGS. 5A  and B and  FIG. 3  show a twenty slat moving floor system. One notable difference between  FIGS. 5A  and B and  3  is that  FIGS. 5A  and B shows twenty cylinders  544  each with a corresponding piston position sensor  542 . Each cylinder  544  is mechanically coupled directly to a slat (not shown) without the use of a cross driver. There are several advantages of eliminating the need for a cross driver. One advantage is eliminating cross drivers can reduce the size of the cylinders. Additionally, cross drivers add a large amount of weight to the system and therefore reduce the amount of weight that can moved in the load. Furthermore, cross drivers are problematic due to bolts breaking and the need to access the middle of a trailer in order to repair them. Eliminating cross drivers can reduce the overall cost of the moving floor system. 
     The moving floor system shown in  FIGS. 5A  and B can effectively be considered to be the equivalent of five, four cylinder moving floor systems. The electronic control unit  554  receives piston position movement from all twenty pistons  544  and controls the movement of the pistons  544  such that at any given time fifteen of the pistons are moving forward and five of the pistons are moving backward. 
     It will be apparent to one of ordinary skill in the art that aspects of the present invention can be implemented as a software application running on a mobile device such as a mobile phone or a tablet computer. 
     While the invention has been described in conjunction with several specific embodiments, it is evident to those skilled in the art that many further alternatives, modifications and variations will be apparent in light of the foregoing description. Thus, the invention described herein is intended to embrace all such alternatives, modifications, applications, combinations, permutations, and variations as may fall within the spirit and scope of the appended claims.