UNEQUAL LENGTH ALTERNATING HYDRAULIC CYLINDER DRIVE SYSTEM FOR CONTINUOUS MATERIAL OUTPUT FLOW WITH EQUAL MATERIAL OUTPUT PRESSURE

• US 20090220358A1
• Filed: 02/29/2008
• Published: 09/03/2009
• Est. Priority Date: 02/29/2008
• Status: Abandoned Application

• Current Assignee: Putzmeister America, Inc. (Putzmeister Concrete Pumps GmbH)
• Original Assignee: Putzmeister America, Inc. (Putzmeister Concrete Pumps GmbH)
• Inventors: Krivsky, Andrew J., Sweet, Brian G.
• Application Number:
  US12/039,926
• Publication Number:
  US 20090220358A1
• Time in Patent Office: Days
• US Class Current: 417/254
• CPC Class Codes: F04B 11/0075 connected in series
• CPC Class Codes: F04B 15/023 supply of fluid to the pump by gravity through a hopper, e.g. without intake valve
• CPC Class Codes: F04B 9/1095 having two or more pumping chambers in series

Abstract

A hydraulic pumping system is provided for delivering a compressible fluid material from a hopper to an outlet. A primary hydraulically driven pumping unit has a first interior volume for receiving the fluid material from the hopper. A secondary hydraulically driven pumping unit is interconnected with the primary hydraulically driven pumping unit and has a second interior volume less than the first interior volume for receiving fluid material from the primary hydraulically driven pumping unit. The primary and secondary hydraulically driven pumping units have hydraulically driven reciprocating piston units with unequal stroke lengths. The piston units are alternately reciprocated to fill the first interior volume of fluid material from the hopper, pump a portion of the first interior volume of fluid material into the second interior volume and the remainder of the first interior volume to the outlet, and pump the second interior volume of fluid material to the outlet while fluid material is being pulled into the first interior volume in a sequential and simultaneous manner which will produce substantially continuous delivery of fluid material to the outlet.

Claims

1. A hydraulically driven pumping system for delivering a compressible fluid material from a hopper to an outlet, the system comprising:

a primary hydraulically driven pumping unit having a first interior volume for receiving the fluid material from the hopper; and

a secondary hydraulically driven pumping unit interconnected with the primary hydraulically driven pumping unit and having a second interior volume less than the first interior volume for receiving fluid material from the primary hydraulically driven pumping unit,

the primary and secondary hydraulically driven pumping units having hydraulically driven reciprocating piston units with unequal stroke lengths, the piston units being alternately reciprocated to fill the first interior volume with fluid material from the hopper, pump a portion of the first interior volume of fluid material into the second interior volume and the remainder of the first interior volume to the outlet, and pump the second interior volume of fluid material to the outlet while fluid material is being pulled into the first interior volume in a simultaneous and sequential manner which will produce substantially continuous delivery of fluid material to the outlet.

2. The pumping system of claim 1, wherein the piston units are reciprocated in primary and secondary hydraulic cylinders having equal bores, unequal lengths, and pistons with equal diameters.

3. The pumping system of claim 1, wherein the piston units are reciprocated in primary and secondary material cylinders having equal bores, unequal lengths that have substantially equal output pressures, and pistons with equal diameters.

4. The pumping system of claim 1, wherein a single check valve is positioned between the hopper and the primary pumping unit.

5. The pumping system of claim 4, wherein a single check valve is positioned between the primary pumping unit and the secondary pumping unit.

6. A hydraulically driven pumping system for delivering a compressible fluid material from a hopper to an outlet, the system comprising:

a primary hydraulically driven pumping unit having a primary material cylinder having a piston, a bore and a first interior volume for receiving the fluid material from the hopper, a primary hydraulic cylinder provided with a piston, and a bore and fed by a source of hydraulic fluid and a primary piston unit movable back and forth over a stroke length within the primary material cylinder and the primary hydraulic cylinder;

a secondary hydraulically driven pumping unit having a secondary material cylinder having a piston, a bore and a second interior volume less than the first interior volume for receiving the fluid material from the primary material cylinder, a secondary hydraulic cylinder provided with a piston and a bore and sized smaller than the primary hydraulic cylinder and fed by the source of hydraulic fluid, and a secondary piston unit movable back and forth over a stroke length within the secondary material cylinder and the secondary hydraulic cylinder, a stroke length of the secondary piston unit being less than the stroke length of the primary piston unit;

a first check valve located between the hopper and the primary material cylinder; and

a second check valve located between the primary material cylinder and the secondary material cylinder,

wherein the primary and secondary piston units are hydraulically controlled and alternately reciprocated over their respective unequal stroke lengths to fill the first interior volume with fluid material from the hopper, pump a portion of the first material volume of first interior volume of fluid material into the second interior volume and the remainder to the outlet, and pump the second interior volume of fluid material to the outlet while the fluid material is being pulled into the first interior volume in a sequential and simultaneous manner which will produce substantially continuous delivery of fluid material to the outlet.

7. The pumping system of claim 6, wherein the primary and second material cylinders have equal bore and piston diameters and unequal lengths.

8. The pumping system of claim 6, wherein the primary and secondary hydraulic cylinders have equal bore and piston diameters and unequal lengths.

9. The pumping system of claim 6, wherein each of the primary and secondary piston units include material piston adapters and hydraulic cylinder rods.

10. The pumping system of claim 9, wherein the hydraulic cylinder rods of the primary and secondary piston units have unequal diameters and lengths.

11. The pumping system of claim 9, wherein the hydraulic cylinder rod of the primary piston unit has a diameter that is greater than a diameter of the hydraulic cylinder rod of the secondary piston unit.

12. The pumping system of claim 6, wherein the primary and secondary material cylinders have outlet pressures that are equalized by appropriately sizing the primary and secondary material cylinders with equal bore and piston diameters, sizing the primary and secondary hydraulic cylinders with equal bore and piston diameters, and driving the primary and secondary piston units alternately by the same hydraulic pump.

13. The pumping system of claim 6, wherein proximity sensors are included within the primary and secondary pumping units for detecting a fully extended position of the primary and secondary piston units.

14. The pumping system of claim 6, wherein the primary and secondary hydraulic cylinders are hydraulically connected to each other and to a source of secondary hydraulic pump pressure.

15. The pumping system of claim 6, wherein the material output rate is infinitely variable by controlling the hydraulic fluid supplied to the primary and secondary hydraulic cylinders.

16. The pumping system of claim 6, wherein the primary and secondary piston units have equal extension speed.

17. The pumping system of claim 6, wherein the primary and secondary piston units have unequal retraction speed.

18. The pumping system of claim 6, wherein the volume of the primary material cylinder is substantially twice the volume of the secondary material cylinder.

19. A method of delivering a substantially constant flow of fluid material from a hopper to an outlet using a hydraulically driven pumping system, the method comprising the steps of:

a) providing a primary hydraulically driven pumping unit having a first interior volume for receiving the fluid material from the hopper;

b) providing a secondary hydraulically driven pumping unit interconnected with the primary hydraulically driven pumping unit and having a second interior volume less than the first interior volume for receiving fluid material from the primary hydraulically driven pumping unit;

c) providing the primary and secondary hydraulically driven pumping units with hydraulically driven reciprocating piston units with unequal stroke lengths; and

d) alternately reciprocating the piston units to fill the first interior volume with fluid material from the hopper, pump a portion of the first interior volume of fluid material into the second interior volume and the remainder of the first interior volume to the outlet, and pump the second interior volume of fluid material to the outlet while the fluid material is being pulled into the first interior volume in a sequential and simultaneous manner which will produce substantially continuous delivery of fluid material to the outlet.