Abstract:
A method of transferring flowable concrete containing aggregate to a desired location at substantially constant rate without sharp variations in pressure and a power driven pump that may be used to carry out the method. The pump requires no valves, is highly abrasive resistant, has a high constant flow rate discharge due to not operating intermittently, and subjects the conduit or hose through which the concrete discharges to a minimum of strain as the concrete flows at a substantially constant rate therethrough with no sharp variations in pressure, and with minimum frictional resistance.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Concrete Pump and Method of Using Same. 
     2. Description of the Prior Art 
     Prior to the present invention, the most successful pumps used in pumping flowable concrete employed reciprocating pistons and associated valving, with the pistons stopping at the end of each stroke. Thus, concrete moves intermittently through a hose or conduit connected to the discharge of a reciprocating pump. The friction of the flowable concrete in a hose is highest when being accelerated from a rest position to the maximum rate of flow. This intermittent flow makes the discharge of flowable concrete from the hose erratic and difficult to direct into a concrete form. 
     A major object of the present invention is to provide a method of pumping flowable concrete containing large pieces of aggregate at a substantially constant rate without sharp variations in pressure and in so doing overcome the major operational disadvantages inherent in prior art reciprocating pumps used in pumping concrete. 
     Another object of the invention is to supply a concrete pump that is compact, requires no valves, is easily cleaned, discharges the concrete at a substantially uniform rate without sharp variations in pressure, and a pump that when it encounters a piece of aggregate will cut the latter into portions that will pass through the pump. 
     These and other objects and advantages of the present invention will become apparent from the following detailed description of the structure of the concrete pump and method of using the same to transfer flowable concrete to a desired location at a substantially uniform rate and without sharp variations in pressure. 
     SUMMARY OF THE INVENTION 
     A vertically extending circular confined space is defined within a housing that has first and second side walls and an end wall. The first side wall has a centered inlet opening therein that is in communication with a hopper having steep downwardly extending walls. 
     A power driven shaft extends into the confined space through an opening in the second side wall. The shaft rotatably supports a heavy circular plate adjacent the second side wall, with the surface of the plate nearest the second side wall having a number of shallow radially extending ridges thereon. 
     The circular plate on the outer third portion thereof supports a number of circumferentially spaced bolts that extend towards the first side wall. The bolts on the free ends thereof support another circular plate that has a centered tapered opening therein. The bolts in cooperation with spacers mounted thereon support a number of ring-shaped discs between the two plates in laterally spaced relationship. The spaces between the discs are of sufficient width to permit the majority of the aggregate in the flowable concrete to pass therethrough. The outer peripheries of the two circular plates taper inwardly towards one another. 
     A rectangular cut water is formed in an outer portion of the end wall and communicate with a diffuser of the same transverse cross-section, but the diffuser also developing into a transverse circular cross-section to serve as a transition. The portion of the diffuser of circular transverse cross-section is connected to the hose or conduit that extends to the desired location. 
     Flowable concrete is intermittently dumped into the hopper and flows by gravity into the confined space. The rotating plates and ring-shaped discs have boundary layers of the concrete that adhere thereto, with the boundary layers merging into the balance of the concrete in the confined space. The two circular plates and ring-shaped discs as they rotate shear the boundary layers from the concrete in the confined space and in so doing cause the concrete to rotate as a circular body. Due to this rotation, and the centrifugal force imposed thereon, concrete entering the confined space moves in an outwardly directed spiral path, with the aggregate therein passing through the spaces between the ring-shaped discs. 
     The concrete discharges with stream line flows into the diffuser, and is discharged therefrom at a substantially constant rate and without any sharp variations in pressure into the hose or conduit where it flows therethrough with minimum frictional resistance. The angle of the diffuser is critical, for if it is too great the flowing concrete will separate therefrom and become turbulent in flow with resultant clogging of the diffuser. 
     Pieces of aggregate entering the confined space that are too large to pass through the spaces between the discs are cut into smaller portions by the rotating knives that will so pass therethrough. The tapered peripheral edges of the two plates serve to roll or direct concrete in the outer portion of the confined space back into the ring shaped discs, and in so doing prevent the build up of aggregate in the confined space that would jam rotation of the plates and ring-shaped discs. The radially extending discs on the plate closest the second side wall act as a pump to direct concrete away from the sealed opening through which the shaft, and minimizes the posibility of this sealed opening, leaking. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of the pump; 
     FIG. 2 is a transverse cross-sectional view of the pump taken on the line 2--2 of FIG. 1; 
     FIG. 3 is a cross-sectional view of the pump taken on the line 3--3 of FIG. 2; and 
     FIG. 4 is a fragmentary front elevational view of one of the locks that hold the first side wall in a confined space defining position with the end wall and second side wall. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The concrete pump A as may best be seen in FIGS. 1 and 2 includes a housing B that is defined by a first vertical side wall 10, second side wall 12 that is laterally spaced a substantial distance from the first side wall, and an end wall 14 that extends between the side walls and cooperates therewith to define a circular confined space 17. The first side wall 10 has a tapered centered inlet opening 18 therein. 
     Second side wall 12 has a centered opening 20 therein from which a cylindrical shell 22 extends outwardly. A first heavy wall circular plate 24 is disposed in confined space 17 adjacent first side wall 10. The confined space 17 has a second heavy wall circular plate 26 disposed therein adjacent second side wall 12. A bearing 30 is mounted in shell 22 and has longitudinally spaced seats 32 situated between it and second side wall 12 in the shell 22. The seals 32 have a space 34 therebetween. A tube 36 extends from space 34 and communicates with opening 18 as shown in FIG. 3. The free open end of shell 22 is closed by an end piece 38 that has a seal 40 therein. 
     A shaft 42 is rotatably supported by bearing 30 and has a coupling 44 on the outer end thereof that is connected to the drive shaft 46 of a conventional prime mover 48 such as an electric motor or the like. The inner end of shaft 42 is connected to the center of the second circular plate 26. Housing B is mounted on a conventional base 50 as shown in FIG. 1. The first side wall 10 has a number of circumferentially spaced rigid strips 52 extending outwardly therefrom as shown in FIGS. 3 and 4, with each strip having a slot 54 that extends inwardly from the outer end thereof. A number of screws 56 are provided that have eyes on first ends thereof that pivotally engage pins 58 that are supported from the outer surface of end wall 14 by lugs 60. The screws 56 have threaded portions 62 that project outwardly beyond the strips 52 when the screws are positioned in slots 54. The threads 62 are engaged by wing nuts 64. A circumferentially extending groove 53 is formed in an end surface of end wall 14 and supports a resilient ring 55 therein. The resilient ring 55 is in pressure sealing contact with first end wall 10 when the wing nuts 64 are tightened on the screws 56 as shown in FIG. 3. By loosening the wing nuts 64, the screws may be pivoted outwardly and the first side wall 10 removed from the housing B to permit the cleaning of the interior thereof. 
     A number of circumferentially spaced transverse bores 66 are formed in the outer one third portion of the second circular plate 26 that support bolts 68 that extend towards first plate 24. Each bolt 68 includes a head 68a, and a shank 68b that has threads 68c on the portion thereof closest to first plate 24. Each of the bores 66 includes an enlarged outer portion in which a bolt head 68a is disposed in a recessed position as illustrated in FIG. 3. The threads 68c engage tappered bores 24a formed in the first plate 24 as shown in FIG. 3. A number of ring-shaped discs 70 are provided that have a number of circumferentially spaced transverse bores 72 therein through which the shanks 68b of the bolts 68 extend. Each bolt 68 has a number of cylindrical spacers 74 mounted thereon that serve to maintain the ring-shaped discs 70 in laterally spaced relationship to one another and to the first and second plates 24 and 26. The ring shaped discs 70 are separated by spacers 71 of sufficient width to permit the majority of aggregate E in concrete F to pass outwardly therethrough. 
     The inner peripheral portion of each of the disc shaped members 70 is shaped to define two inwardly extending circular surfaces 70a that meet at a sharp apex 70b that serves as a circular knife edge. A minor portion of the aggregate E may have pieces E-1 of such magnitude as to not be able to pass outwardly through one of the spaces 71. Due to the centrifugal force exerted on aggregate E-1, it is forced outwardly to contact knife edges 70b as shown in phantom line in FIG. 3, and be severed into aggregate particles E that will pass through the spaces 71. 
     A hopper C is shown in FIG. 1 that intermittently has flowable concrete F dumped therein. The hopper C includes a curved upwardly extending and outwardly tapering delivery conduit 76 that on the upper end develops into upwardly extending, outwardly tapering end walls 78 and 80 and sidewalls. The hopper C is held in a fixed position relative to the pump B by conventional support means (not shown). 
     A cut water opening 90 is formed in an outer extremity of end wall 14, which cut water is of rectangular transverse cross section. The cut water 90 is in communication with a diverging diffuser 91 that has sidewalls 92 and end walls 94 that provide a transition to a conduit or hose 96 of circular transverse cross section. The side walls 92 and end walls 94 should not taper outwardly relative to the centerline 98 by more than seven degrees, for at an angle greater than this the concrete being discharged tends to separate from the end walls and side walls with the flow then becoming turbulent. Aggregate then may tend to separate from the flowable concrete and build-up in the interior of the diffuser 91 to the extent that flow of concrete therethrough is blocked. 
     As an illustration of the compactness of the pump A, concrete F having aggregate E up to one and one half inch in size may be pumped using ten inch diameter circular plates 24 and 26, with the diameter of the inner peripheries of the ring-shaped discs being four inches. It has been found from experience that irrespective of the size of the pump, best results are obtained when a ratio of two and one half is maintained between the diameter of the ring-shaped discs 70 and the inner peripheries thereof that define the knife edges 70b. For one and one half inch aggregate it has been determined that the cut water should be two inches times four and one half inches and free of sharp edges to prevent the cut water opening being obstructed by aggregate E. The diffuser 91 provides a transition to the hose or conduit 96 having a four inch interior diameter. It will be noted that the hopper C has steep end walls and side walls, and particularly no flat substantially horizontal surface. Flat surfaces will cause the concrete E to bridge and jam the entrance into pump B. 
     In operation, the concrete E flows by gravity from hopper C into confined space 17 where rotary motion is imparted thereto. The incoming concrete E due to centrifugal force imposed thereon tends to move outwardly in a spiral path and discharge through cut water 90. The movement of concrete E in confined space 17 is stream line with the concrete moving outwardly through the spaces 71 between the ring-shaped discs 70. This stream line flow of concrete E continues through diffuser 91 and hose or conduit 96. Thus it will be seen that the concrete E discharges at a substantially constant rate and without sharp variations in pressure through hose or conduit 96. The flow of concrete E through hose 96 is with a minimum of frictional resistance as there is a constant rather than a pulsating flow as occurs when prior art reciprocating pumps are used. 
     The tapered circumferential surfaces 24a and 26a on first and second circular plates 24 and 26 results in concrete E being rolled over and directed into ring-shaped discs 70 and thus substantially precludes the build up of aggregate E between housing B and plates 24 and 26, and ring-shaped discs 70 to the extent that the plates and discs cannot rotate.