Abstract:
A reciprocating liquid or gas pump is driven by bi-directional force. A prime mover causes eccentric weights to rotate, which in turn cause pistons to be driven in linear paths under bi-directional force. This bi-directional force then drives opposing sets of pistons to pump a fluid. The pressurized fluid can then be used for, e.g., driving a hydraulic motor.

Description:
FIELD OF INVENTION 
     This invention is in the field of fluid pumps, more specifically in the field of mechanical pumps, and more specifically still in the field of positive displacement pumps. More specifically still, it is in the field of reciprocating pumps. 
     BACKGROUND OF INVENTION 
     The reciprocating pump is a specific type of positive displacement pump in which a constant and fixed volume of fluid is drawn into a cylinder by a retreating piston and then discharged under pressure. Its chief virtue compared with other types of positive displacement pumps such as vane, lobe, and screw pumps is that because of the good seal typically achievable between a piston and its cylinder wall, back-leakage of fluid around the piston is low compared to back-leakage of fluid in the other types. This is because a piston and its cylinder meet along a two-dimensional cylindrical surface, whereas a pump vane, screw, or lobe contacts its casing along a line. Thus, reciprocating pumps can deliver very high pressures with relatively high efficiency. 
     Typically the pistons in a reciprocating pump are driven by connecting rods that are in turn driven by a crankshaft. The connecting rods convert the rotational motion of the crankshaft into linear reciprocal motion of the piston. However, the connecting rods are only directly in line with the motion of the pistons at the top and bottom of the piston travel within the cylinder. Thus, along the rest of the path of the piston, the connecting rods are applying a sidewards force to the piston against the cylinder wall. This generates heat, wear, and pulsating stress on the pumping parts. The heat represents a loss of efficiency. These effects increase as the pressure rating of the pump is increased, that is, particularly in instances where such a pump is the pump of choice. 
     BRIEF DESCRIPTION AND OBJECTS OF INVENTION 
     A mechanical bi-directional centripetally-powered reciprocating liquid or gas pump is provided that converts a rotational force from an outside power source into a centripetal bi-directional force. The bi-directional force then drives opposing sets of pistons to pump liquid or gas. To achieve this the outside power source is applied to a gear train that powers right angle gearboxes. These gearboxes are paired to receive opposite rotations. 
     There is an additional pair of gearboxes and eccentrics rotating in the opposite direction to the first pair. As the gearboxes rotate the eccentrics, the two pairs of gearboxes oscillate toward and away from each other, thus providing force from opposite directions, i.e., bi-directionally. Each gearbox is attached to a straight shaft with a piston assembly attached to each end of the shaft. These piston assemblies are installed into cylinders that are attached to each end of the entire assembly unit. The cylinders are equipped with intake and discharge valves for positive displacement of fluid. 
     The oscillation of the pistons is caused, in this invention, by the oscillation of the gearboxes in centripetal reaction to the rotation of the eccentrics. The motion of the gearboxes, which are fixed by straight shafts to the pistons, is always collinear with the motion of the pistons. There are no connecting rods that, in addition to moving to and fro within the cylinder, also move from side to side in relation to the cylinder walls. Thus it is a principal object of this invention to reduce friction, heat and wear between the piston and the cylinder and improve pump efficiency. 
     Further, the eccentrics provide increased pressure on the liquid in the cylinder in direct response to any increases in the back pressure against the discharged liquid. Any pulsation in forces due to variations in pumping effort are therefore only transmitted as far back as the gearboxes and are absorbed by the eccentrics rather than being transmitted all the way back to the gear train and outside power source. Thus it is another object of the invention to reduce stress on the power train of the device. 
     Still further, the eccentrics provide inertial mass to the extent desired to smooth load on the motor without having to add a flywheel. Thus it is another object of the invention to simplify the construction of a reciprocating pump. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a top view of the apparatus. 
         FIG. 2  is a side view of the apparatus. 
         FIG. 3  is a front view of the drive gear train. 
         FIG. 4  is a rear view of an interior plate. 
         FIG. 5  is a front view of an interior plate. 
         FIG. 6  is a rear view of an exterior plate. 
         FIG. 7  is a front view of an exterior plate. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     Referring now to the drawings, in which like reference characters in the several figures represent like elements in all the figures, the centripetally-powered reciprocating pump is constructed and assembled as follows: 
       FIG. 1  is a top view of the apparatus, showing the complete unit less the drive motor. It principally comprises a case  1  with four gearboxes  2   a - d , eight cylinders  3   a - h , eight eccentrics  4   a - h  (only four of which,  4   a - d , are visible in this view). four piston rods  5   a - d , eight pistons  12   a - h  (only one,  12   a , visible in a cutaway of cylinder  3   a  here, the remainder within cylinders  3   b - h ), and four splined shafts  8   a - d . The splined shafts  8  are rotated by a centrally-mounted gear train  9  driven by a motor (omitted for clarity). The splined shafts  8  in turn rotate bevel gears (see, e.g.,  10   a  and  10   b  in the cutaway of gearbox  2   a ) in the gearboxes  2 , which in turn swing the eccentrics  4  around. 
     The gearboxes consist of three-shaft construction. The splined input shaft  8  to each gearbox turns an input bevel gear  10   a  within the gearbox (see cutaway) which in turn drives two output bevel gears at right angles to the input bevel gear (only output bevel gear  10   b  is visible in the cutaway). The output gears then drive short upper and lower shafts at right angles to the input shaft (only lower shaft  15  is visible in the cutaway). Two eccentric masses are attached to the upper and lower shafts respectively, which rotate in the same plane as the output bevel gears in the gearbox. 
     The centripetal force of the gearboxes  2  in reaction to the rotating eccentrics  4  along their arms  11   a - d  as they rotate pulls the gearboxes right and left horizontally in this view. The gearboxes are affixed to the piston rods  5  by tie plates  7   a - b , so that the gearboxes drive the piston rods right and left. The piston rods  5  push and pull the pistons  12 , drawing fluid into cylinders  3  through inlet valves  13  and pumping it out through outlet valves  14  ( 13   a  and  14   a  shown). 
     One of the four gearboxes,  2   a , and one of the eight cylinders,  3   a , are shown in cutaway. The right-hand pair of gearboxes  2   a  and  2   b  are paired and joined together with tie plate  7   a  so that they oscillate together horizontally in this view. The piston rods  5   a  and  5   b  are also affixed to the tie plate  7   a  so that as the gearboxes  2   a  and  2   b  oscillate, the piston rods  5   a  and  5   b  move with them. The left-hand end also has paired gearboxes timed with the same motion. The two sets of paired gearboxes are timed to oscillate toward and away from each other horizontally, simultaneously, as the eccentrics rotate. This assures that the horizontal motion of mass is balanced so that the entire apparatus does not experience horizontal vibration. The right-hand pair of eccentrics  4   a  and  4   b  counter-rotate with respect to each other, as does the left-hand pair  4   c  and  4   d , so that the vertical and horizontal vibrational components of their motion also cancel out. It is well to note in addition that the pairs of eccentrics are offset on their respective output shafts in the plane of view so that their planes of rotation do not intersect, thereby making sure they do not collide. 
     Thus, to summarize the motion of one-half of the total moving parts in this view, gear train  9  turns splined shafts  8   a  and  8   b , which, through bevel gears  10 , cause eccentrics  4   a  and  4   b  to rotate. This rotation drives gearboxes  2   a  and  2   b  to and fro horizontally, which, through tie plate  7   a , drives  115  piston rods  5   a  and  5   b  to and fro. This in turn causes pistons  12   a  etc. within cylinders  3   a - d  to reciprocate and pump fluid. 
       FIG. 2  is a side view of the apparatus, that is, as seen from the right in  FIG. 1 , with some cutaway views. The right side of this figure shows a cutaway of cylinder  3   a , rendering piston  12   a  visible, driven by piston rod  5   a . The cylinder  3   a  has a pressed-fit cast iron sleeve  20  into an aluminum  120  sleeve  21 . This aluminum sleeve  21  further comprises cooling fins  22  that are machined into it for dissipation of heat. The inner end of each cylinder, through which the piston rods pass, is defined by interior plates  28   a - b . (Only piston rod  5   a  is shown here.) The outer end of each cylinder to which the valves are attached is defined by exterior plates  29   a - b.    
     The piston rod  5   a  is shown in broken view to better illustrate other parts. 
     In this view, not only are eccentrics  4   a  and  4   d  (of  FIG. 1 ) visible, but also cooperating eccentrics  4   e  and  4   h  can be seen on the underside of the apparatus. A cutaway of a gearbox  2   a  shows the interior of the gearbox. The gearboxes are driven by splined shafts  8   a  and  8   b , which oscillate left and right along with the gearboxes. The end of each splined shaft farthest from the gear train  9  drives a gearbox to and fro, and rotates about its axis within a thrust bearing  33  at the gearbox. Thrust bearing  33  is capable of withstanding oscillating thrust in either direction. Each splined shaft is supported near its other end at gear train  9  by passing through a ball nut  32  mounted in bulkhead  24 , which allows the splined shaft to turn as well as oscillate right and left within it. There is enough room between left splined shaft  8   a  and right splined shaft  8   b  to allow them to oscillate in opposite directions without interference. Alternatively, the axes of the splined shafts may be offset slightly to keep them from colliding. 
     In this drawing, cylinder  3   a  is the cutaway cylinder at right. Piston  12   a  within it, and piston  12   d  (hidden within cylinder  3   d  at left) move together by being fixed to either end of piston rod  5   a . The piston rods in the apparatus are further equipped with return springs, such as  26   a - b  shown here. These springs return the pistons to the center of their stroke, and are set by collars  27   a - b  in whatever 140 degree of compression is necessary to prevent the pistons from bottoming or topping out during their cycle. 
     The invention as described thus far has eight rotating eccentrics (four above the apparatus in  FIG. 2  and four below). Having four eccentrics above and four below allows further vibration reduction because the offset in the planes of rotation of the eccentrics above can thereby be matched by offsets  145  in the planes of rotation below. Notwithstanding these vibration damping measures, it should be evident that an embodiment of the invention can be made utilizing one eccentric to drive one gearbox, in turn reciprocating one piston. Vibration may not be an issue, or other means (such as an elastic suspension) may be utilized to damp vibration. Similarly, any number of eccentrics can be used to drive any number of pistons within the scope of this invention so long as each embodiment comprises the key feature of using a rotating weight to cause a gearbox to oscillate and drive a piston. 
       FIG. 3  is a front view of the drive gear train  9 , that is, as seen from the bottom of the drawing in  FIG. 1 . Either or both of the upper gears  30   a  or  30   b  may be driven by a motor, and in turn drive lower gears  31   a - b . which in turn drive splined shafts  8   a - b . Piston rods  5   a - d  can be seen passing through bulkhead  24 . 
       FIG. 4  is a rear view of one of the two interior plates,  28   b , that is, a view of the plate as seen from the left in  FIG. 2 . In this figure are shown cast iron bushings  40  with seals  41  through which the piston rods  5   a - d  go into the cylinders. Also seen are the ends of bolts  42  which clamp the cylinders (not shown in this view) between this plate and exterior plate  29   b  (see  FIG. 7 ). 
       FIG. 5  is a front view of interior plate  28   b . This is the side of the plate facing cylinders  3   g ,  3   c ,  3   d , and  3   h  in  FIG. 1 . The plate is machined with four circular indentations  50  of approximately one-eighth inch depth to accommodate and seal the cylinders, and with holes  51  for bolts. 
       FIG. 6  is a rear view of one of the two exterior plates,  29   b , that is, the side of the plate facing the cylinders. It too is machined with indentations  60  of approximately one-eighth inch depth. It also shows bolt holes  61  and borings  62  to accommodate valves and hydraulic fittings. 
       FIG. 7  is a front view of exterior plate  29   b . It shows hydraulic fittings that employ check valves, exemplified by inlet valve  13  and outlet valve  14 , which direct fluid or gas to and away from the cylinders. Also shown are the heads of clamping bolts  42 . 
     The check valves  14  serving as outlets from each cylinder are directed to a supply tank, pressure tank, and/or manifold (not shown). This pressure supply can be directed to hydraulic motors or into a turbine, to achieve rotary power from bi-directional centripetal force.