Patent Publication Number: US-6986303-B2

Title: Displacement shift valve and pumping apparatus and methods using such a valve

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to apparatus and methods for pumping bulk materials, such as concrete, and more particularly, to valves for switching pumping devices between different operating configurations and apparatus and methods for pumping flowable materials using such valves. 
   BACKGROUND 
   Apparatus for pumping concrete and other bulk materials are well known. For example, U.S. Pat. No. 6,299,416 to Kwag discloses a pump device that includes a pair of hydraulic drive cylinders. Each cylinder includes an axial bore and a drive piston coupled to a piston rod that is able to slide within the respective bore, thereby dividing the bore into a head chamber and a base chamber. Fluid lines connect the base chamber of each cylinder to an oil pump and the head chambers of the cylinders to each other. 
   Oil is pumped in one direction from the pump into the base chamber of a first of the cylinders, thereby retracting the first piston and rod into the first cylinder. This causes oil to be pushed out of the first cylinder&#39;s head chamber, through a fluid line into the head chamber of the second cylinder, thereby advancing the second piston and rod outwardly from the second cylinder. Oil in the base chamber of the second cylinder is returned to the pump as the second piston and rod are advanced from the second cylinder. 
   The pump is then reversed, thereby pumping oil into the base chamber of the second cylinder to retract the second piston and rod this causes the oil in the head chamber of the second cylinder to be transferred into the head chamber of the first cylinder, thereby advancing the first piston and rod, and returning oil in the base chamber of the first cylinder to the pump. The Kwag patent explains that this reciprocating process may be repeated to drive cylinders or other mechanisms to pump concrete from a hopper into a conduit for delivery to a location where the concrete is to be poured. 
   This method of alternately pumping fluid into the base chambers of a pair of cooperating hydraulic cylinders is known as “rod side operation.” Such arrangements are often used when it is desired to deliver relative high volumes of concrete or other materials at relative low pressures. 
   In addition, pumping devices designed for “head side operation” are also known. These systems alternately pump fluid into the head chambers of a pair of hydraulic cylinders with the base chambers being connected together by a fluid line. Head side operation is generally used to pump relatively lower volumes at higher pressures. 
   Accordingly, apparatus and methods for pumping concrete and other flowable materials would be useful. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to apparatus and methods for pumping flowable materials, such as concrete, and more particularly, to valves for switching pumping devices between different operating configurations and to apparatus and methods for pumping flowable materials using such valves. 
   In accordance with one aspect of the present invention, an apparatus for pumping flowable material is provided that includes a first barrel, a first piston slidable within the first barrel, thereby dividing the first barrel into a first head-side chamber and a first rod-side chamber, a second barrel, a second piston slidable within the second barrel, thereby dividing the second barrel into a second head-side chamber and a second rod-side chamber, and a pump for delivering fluid to the first and second barrels. 
   A valve is provided that is movable between a first position wherein the pump communicates with the rod-side chambers, and a second position wherein the pump communicates with the head-side chambers. Preferably, the valve includes passages therein such that the first head-side chamber communicates with the second head-side chamber in the first position, and the first rod-side chamber communicates with the second rod-side chamber in the second position. 
   In one embodiment, the valve may include ports in the first and second barrels communicating with the first head-side chamber, second head-side chamber, first rod-side chamber, and second rod-side chamber, respectively. The valve may include one or more transfer passages that connect the first head-side chamber port to the second head-side chamber port in the first position, and connect the first rod-side chamber port to the second rod-side chamber port in the second position. 
   Optionally, one or more sensors may be provided for measuring pressure of the system, e.g., in the supply line from the pump or within at least one of the first and second barrels. A controller may be coupled to the valve and the one or more sensors for moving the valve between the first and second positions based upon pressure measured by the one or more sensors. For example, the controller may be configured fork moving the valve to the first position when the pressure falls below a first threshold, and to the second position when the pressure rises above below a second threshold, which may be the same or different than the first threshold. 
   In accordance with another aspect of the present invention, a method is provided for pumping flowable material using a pumping apparatus including first and second drive cylinders. Fluid may be delivered into the cylinders to reciprocate pistons within the cylinders, e.g., from a pump. Pressure within the system, e.g., within at least one of the cylinders, may be monitored, and a direction of flow of the fluid may be switched between at least first and second configurations based upon the pressure. 
   For example, in the first configuration, fluid may be delivered into a rod side of the cylinders when the pressure within at least one of the cylinders is below a predetermined pressure threshold. In the second configuration, fluid may be delivered into a head side of the cylinders when the pressure within at least one of the cylinders exceeds the predetermined pressure threshold or some other threshold. In addition, fluid may be transferred between the head sides of the cylinders in the first configuration, and between the rod sides of the cylinders in the second configuration. 
   Preferably, fluid is delivered alternately between the first and second cylinders such that the piston within the first cylinder is advanced when the piston within the second cylinder is retracted, and the piston within the first cylinder is retracted when the piston within the second cylinder is advanced. Rods may be connected to the pistons such that the rods provide power to pump a flowable material, such as concrete. Thus, fluid may be delivered using either rod-side operation, e.g., for low pressure, high volume output, or head-side operation, e.g., for high pressure, low volume output. 
   Other objects and features of the present invention will become apparent from consideration of the following description taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1A and 1B  are cross-sectional side views of a displacement shift valve, in accordance with the present invention. 
       FIG. 2A  is a schematic of a pumping apparatus including a valve, such as the valve of  FIGS. 1A and 1B , with the valve positioned for rod-side operation. 
       FIG. 2B  is a schematic of the pumping apparatus of  FIG. 2A , with the valve positioned for head-side operation. 
       FIG. 3  is a cross-sectional side view of the drive cylinders of the pumping apparatus of  FIGS. 2A and 2B . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Turning to the drawings,  FIGS. 1A–3  show a preferred embodiment of an apparatus  10  for pumping concrete or other flowable material, in accordance with the present invention. Generally, the apparatus  10  includes first and second drive cylinders  12 ,  32 , a pump  50  for delivering fluid to the cylinders  12 ,  32 , and a valve  60  for controlling the path of fluid flow between the cylinders  12 ,  32  and the pump  50 . 
   Optionally, the apparatus  10  may include other components, e.g., pumping cylinders or other mechanisms (not shown) coupled to the drive cylinders  12 ,  32  such that the drive cylinders  12 ,  32  may provide power to pump concrete or other flowable materials. In addition, the apparatus  10  may include a hopper or other container (not shown) for holding the material being pumped. Furthermore, a frame or other support structure (not shown) may be provided for supporting one or more of the components of the apparatus  10 . The frame may be stationary or may be included on a trailer or vehicle, as is well known to those skilled in the art. 
   With particular reference to  FIG. 3 , each of the first and second drive cylinders  12 ,  32  includes a barrel  14 ,  34  having an axial bore  16 ,  36  therein, and a piston  18 ,  38  dividing the bore  16 ,  36  into a head-side chamber  20 ,  40  and a rod-side chamber  22 ,  42 . Each piston  18 ,  38  is slidable within the respective barrel  14 ,  34  for increasing and decreasing a volume of the head-side chamber  20 ,  30  and rod-side chamber  22 ,  42  inversely proportional to one another as the piston  18 ,  38  reciprocates within the barrel  14 ,  34 , as is well known to those skilled in the art. Each piston  18 ,  38  is connected to a rod  19 ,  39  for providing an output from the apparatus  10  for driving other components (not shown), e.g., for pumping material. 
   One or more sensors may be provided for monitoring pressure within the apparatus  10 , e.g., within the drive cylinders  12 ,  32 . Preferably, a pressure sensor  100  is provided that is coupled to the output of the pump  50 , as explained further below. Alternatively, a pressure sensor (not shown) may be provided in each end of the cylinders  12 ,  32  such that the pressure within the head-side chambers  20 ,  40  and/or rod-side chambers  22 ,  42  may be measured independently and/or simultaneously. In a further alternative, sensors (not shown) may be provided on or adjacent the pistons  18 ,  38  and/or rods  19 ,  39  for measuring an output of the apparatus  10 , e.g., force or power. 
   At least two ports  24 ,  44  are provided in the cylinders  12 ,  32  that communicate with the head-side chambers  20 ,  40 , respectively. Similarly, at least two ports  26 ,  46  are provided that communicate with the rod-side chambers  22 ,  42 , respectively. The locations of the ports  24 ,  26 ,  44 ,  46  shown in  FIG. 3  are merely exemplary, and may be provided elsewhere in the cylinders  12 ,  32 . Fluid lines  28 ,  30 ,  48 ,  49  extend from the ports  24 ,  26 ,  44 ,  46  to the valve  60 , as explained further below. The lines  28 ,  30 ,  48 ,  49  may be formed from conventional hoses, tubing, and the like capable of operating under the pressures normally encountered during operation of high pressure pumping apparatus and are substantially corrosion-resistant to the fluid passing through, the lines  28 ,  30 ,  48 ,  49 . The ports and or lines may include conventional connectors (not shown) for substantially permanently or removably securing the lines to the respective ports. 
   Optionally, the cylinders  12 ,  32  may include other components known in the art that are not important to the present invention. For example, one or more bypass lines (not shown) may be provided adjacent to the ends of the cylinders  12 ,  32  for braking the pistons  18 ,  38  as they approach the ends of their strokes. Additional information on drive cylinders or pumping system components that may be appropriate for use with the present invention are found in U.S. Pat. No. 6,299,416, the disclosure of which is expressly incorporated herein by reference. 
   Returning to  FIGS. 2A and 2B , the pump  50  includes a pumping device  52 , e.g., including a motor (not shown) and the like, and may be any conventional pumping device capable of generating the pressures and volumetric flow rates appropriate for driving the cylinders  12 ,  32 . Preferably, the pump  50  includes an outlet line  56  for delivering fluid, generally substantially incompressible fluids, such as oil, at desired pressures and flow rates. In addition, the pump  50  includes an inlet line  58 , which may include a collection pan or other container  59  for collecting fluid returned from the cylinders  12 ,  32 . The outlet  56  and inlet  58  are connected by lines  72 ,  74  to the valve  60 , which may transfer the fluid to the cylinders  12 ,  32 , as explained further below. The pump  50  may include a valve or other switching mechanism  54  for reversing flow from the pump  50 , i.e., such that during alternate cycles, the lines  72 ,  74  may supply fluid to and/or return fluid from the cylinders  12 ,  32 , as explained further below. Alternatively, the pump  50  may be a reversible pump that may pump fluid alternately in one direction and in an opposite direction (i.e., such that the outlet  56  and inlet  58  alternate). 
   The pump  50  may include one or more sensors  100  for measuring pressure within the apparatus  10 , e.g., within the outlet line  56  and/or the inlet line  58 . The pressure measured by the sensor(s)  100  may be substantially proportional to the pressure within the cylinder(s)  12 ,  32 , thereby providing an indication of the load being imposed on the apparatus  10 . 
   Turning to  FIGS. 1A and 1B , the valve  60  generally includes a housing  62 , and a body  64  movably mounted within the housing  62 . Although a single housing  62  is shown, it will be appreciated by those skilled in the art that the valve  60  may include multiple housings and/or manifolds connected to one another (directly or by various fluid lines). In addition or alternatively, the housing(s) may include multiple internal parts (not shown) instead of the single body shown that may move in a desired manner to create the desired passages through the valve, as described further below. The configuration of the passages within the valve  60  is merely exemplary, and may be modified based upon desired physical geometry and/or performance criteria, as is well known to those skilled in the art. 
   In addition as shown in  FIGS. 2A and 2B , an actuator  66  may be coupled to the valve  60  for moving the body  64  within the housing  62  (not shown in  FIGS. 2A and 2B ). The actuator  66  may include any controller or system that may move the body  64  (or other components of the valve  60 ) to one or more positions within the housing  62 . For example, the actuator  66  may include a motor, magnet, or other device (not shown) that may be coupled mechanically, magnetically, or otherwise to the valve  60  for selectively moving the body  64  within the housing  62 . In one embodiment, the body  64  may be biased to a first position, e.g., by one or more springs, and the actuator  66  may overcome the bias to move the body  64  to a second (or additional) position. Thus, when the actuator  66  is deactivated, the body  64  may automatically return to the first position. In a preferred embodiment, the valve  60  may be a spring return valve biased to the first position, i.e., for “rod-side operation,” as explained further below. 
   The actuator  66  may include a processor or other circuitry that may be coupled via a communication line  63  to the pressure sensor(s)  100  within the pump  50  for acquiring pressure data and moving the body  64  in response to data measured by the sensor(s)  100 , as discussed further below. Alternatively, the actuator  66  may be coupled to other sensors (not shown) for monitoring other parameters of the cylinders  12 ,  32  or elsewhere in the apparatus  10 . For example, power of force output by the cylinders  12 ,  32  may be monitored in addition to or instead of pressure, and the actuator  66  may move the body  64  based upon the monitored parameter(s). 
   Returning to  FIGS. 1A and 1B , the valve  60  generally includes a plurality of passages extending therethrough for delivering fluid between the pump  50  and the cylinders  12 ,  32  In addition, the valve  60  may include one or more transfer passages for transferring fluid between the cylinders  12 ,  32  The valve  60  may include a number of seals and the like (not shown) for substantially sealing the passages from one another and/or otherwise preventing substantial leakage, as is well known to those skilled in the art. 
   For, example, as shown in FIGS,  1 A– 2 B, the housing,  62  may include pump ports  68 ,  70  that may be connected to the pump  50  by fluid lines  72 ,  74 . The pump ports  68 ,  70  and/or fluid lines  72 ,  74  may include connectors, e.g., including flanges, bolts, and the like, for attaching the fluid lines  72 ,  74  to the ports  68 ,  70 , similar to the fluid lines connected to the ports of the drive cylinders  12 ,  32  discussed above. Ports  76 ,  78 ,  80 ,  82  may be provided that may be connected to the ports  24 ,  44 ,  26 ,  46  in the drive cylinders  12 ,  32  via the fluid lines  28 ,  48 ,  30 ,  49 . 
   The body  64  may include passages that extend between the pump ports  68 ,  70  and ports  76 ,  78 ,  80 ,  82  when the body  64  is in one or more positions within the housing  62 . In addition, the body  64  may include one or more transfer passages that may be used to connect the drive cylinders  12 ,  32  to one another. For example, as shown in  FIG. 1A , in a first position, passages extend between pump ports  68 ,  70  and ports  80 ,  82 , respectively. In the first position, transfer passage  94  connects ports  76 ,  78  to one another. In a second position, shown in  FIG. 1B , passages  84 ,  86  extend between pump ports  68 ,  70  and ports  76 ,  78 , and transfer passage  88  connects ports  80 ,  82  to one another. 
   Thus, with reference to  FIGS. 1A ,  2 A, and  3 , when the valve  60  is in the first position, the apparatus  10  is configured for “rod-side operation.” During rod-side operation, fluid from the pump  50  may be delivered through the lines  72 ,  74 , the passages  90 ,  92  within the valve  60 , and the lines  30 ,  49  into the rod-side chambers  22 ,  42  see  FIG. 3 ) of the cylinders  12 ,  32 . Rod-side operation may be preferred in situations in which the apparatus  10  requires relatively high volumes of material to be delivered at relatively low pressures. 
   The actuator  66  may receive pressure data from the sensor(s)  100 , e.g., to monitor pressure output by the pump  50 , within outlet and/or inlet lines  56 ,  58 , and/or within the rod-side chambers  22 ,  42 . If the pressure rises above a predetermined threshold, the actuator  66  may move the body  64  to the second position, i.e., to shift the apparatus  10  from rod-side to head-side operation. 
   With the valve  60  in the second position, shown in  FIGS. 1B and 2B , the apparatus  10  is configured for “head-side operation.” Head-side operation may be preferred in situations in which the apparatus  10  may experience relatively high pressures, e.g., between about 2,500–3,200 pounds per square inch (psi), and preferably above about three thousand pounds per square inch (3,000 psi). Consequently, relatively low volumes may be pumped at relatively high pressures using head-side operation. 
   During head-side operation, fluid from the pump  50  may be delivered from the outlet  56  and/or inlet  58 , through the lines  72 ,  74 , the passages  84 ,  86  within the valve  60 , and the lines  28 ,  48  into the head-side chambers  20 ,  40  see  FIG. 3 ) of the drive cylinders  12 ,  32 . If fluid is delivered into the head-side chamber  20  of the first cylinder  12 , i.e., through the port  24 , the piston  18  may be pushed away from the head-side chamber  20 , thereby advancing the rod  19  out of the first cylinder  12 . This action pushes fluid out of the rod-side chamber  22  of the first cylinder  12 , i.e., out the port  26 , through the line  30 , the transfer passage  88 , the line  49 , and into the rod-side chamber  42  of the second cylinder  32  via the port  46 . As fluid enters the rod-side chamber  42 , the piston  38  is pushed away from the rod-side chamber  42 , thereby retracting the rod  39  into the second cylinder  32 . This causes fluid to exit the head-side chamber  40  via the port  44 , and pass through the line  48 , the passage  86 , the line  74  to the inlet  58  and into the pump  50 . 
   Once the pistons  18 ,  38  reach the end of their strokes (which may be monitored using conventional devices and methods), the output of the pump  50  is reversed, i.e., delivering fluid into the head-side chamber  40  of the second cylinder  32 , thereby advancing the rod  39  out of the second cylinder  32 . This transfers fluid from the rod-side chamber  42  through the transfer passage  88  into the rod-side chamber  22  of the first cylinder  12 , causing the rod  19  to retract into the first cylinder  12 . Fluid is then returned to the pump  50  through the line  28 , passage  84 , and line  72 . 
   If the pressure within the drive cylinders  12 ,  32  falls below a predetermined threshold, e.g., between about 2,500–3,200 psi, and preferably below about three thousand pounds per square inch (3,000 psi), the actuator  66  may return the valve  60  to the first position. For example, the actuator  66  may receive pressure data from the sensor(s)  100 , and monitor the pressure relative to the predetermined threshold, which may be set manually or automatically. Once the pressure falls below the threshold, the valve  60  may be switched to the first position. 
   Thus, the apparatus and methods of the present invention may provide a more versatile pumping apparatus. The output from the apparatus may be used to drive a system for delivering concrete or other flowable material, such as food products, plastics, and the like (not shown). Unlike conventional systems, the systems and methods of the present invention are capable of automatically switching between high pressure/low volume and low pressure/high volume outputs, as needed during a particular application. 
   While the invention is susceptible to various modifications, and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that the invention is not to be limited to the particular forms or methods disclosed, but to the contrary, the invention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the appended claims.