Pumps – With condition responsive pumped fluid control
Patent
1991-03-29
1992-07-07
Bertsch, Richard A.
Pumps
With condition responsive pumped fluid control
417343, 417347, 417900, F04B 4900, F04B 1700, F04B 1502
Patent
active
051278065
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a thick matter pump with two feed cylinders which open through front-side openings into a material feed tank and work, in turn, with a tube switch configured inside the material feed tank which is suitable for connection on the intake side alternately to the opening of a feed cylinder and which releases the opening of the other feed cylinder, and is suitable for connection on the output side to a delivery pipe, and with a shutoff device configured in the direction of output flow behind the tube switch.
Pumps of this type are used for conveying concrete and other pasty materials, such as rubble packed with water, as found in tunnel construction, or coal dust packed with water or fuel oil, as used in coal furnaces. The shutoff device in the pressure pipe makes it possible to work against a high pressure without encountering the danger of the material flowing back when the tube switch is reversed. As a tube switch, one should consider above all an S-shaped swing pipe. In general, however, the application of U-shaped swing-pipe tube switches, and Y-shaped (forked) pipe tube switches also lie within the scope of the invention.
Furthermore, it is generally known to provide shutoff devices in the vicinity of the delivery pipe, which can be designed, for example, as seated valves, valve , plates, flap valves, or rotary slide valves.
An object of the invention is to take the necessary precautions to ensure operational reliability of the interlinkage of functional sequences, even when the thick matter pump is conveying compressible media against overpressure.
The solution according to the invention is primarily based on the reflection that the shutoff device must be reversible from its closed position into its open position in accordance with a differential pressure arising between the delivery pipe and the tube switch, and being adjustable by using hydraulic or pneumatic means. The shutoff device should be reversible from the closed position into the open position, above all when a specified pre-compression pressure is reached in the tube switch, preferably exceeding the pressure in the delivery pipe.
According to a preferred embodiment of the invention, the shutoff device is controlled by means of hydraulically or pneumatically operable driving mechanisms. This is preferably accomplished by means of a hydraulic sequencing control in a way which allows the driving mechanisms to be operable in the closing direction of the shutoff device, when a discharge stroke is terminated or reversed in the feed cylinders and before the tube switch is switched over, when there is an unimpeded supply and discharge of pressurized media in the closing direction of the shutoff device, and after the subsequent switching of the tube switch in the opening direction of the shutoff device. Here, an adjustable pressure-keeping device is configured in the pressurized media line for the pressurized media flowing away in the opening direction. To guarantee the unimpeded supply of pressurized media in the closing direction, the pressure-keeping device is effectively bridged over by a back-pressure valve which opens in the direction of inflow. The pressure-keeping device can be designed, for example, as a relief valve or as a pressure-keeping valve. Another improvement in this respect can be attained by mounting an adjustable pressure-keeping device in the pressure-media line, as well, for the pressurized media flowing in the opening direction of the shutoff device.
According to a further preferred embodiment of the invention that provides for one or two tube-switch reversing cylinders and one reversing valve mounted in the hydraulic line leading to these cylinders operable by means of end-position signals from the feed cylinders or their driving cylinders, an additional diverter valve is situated in the hydraulic line leading to the tube-switch reversing cylinders. The diverter valve can be tripped by force in the flow-through direction by means of a signal which is adapted to be tapped off in the blocking position of
REFERENCES:
patent: 3981622 (1976-09-01), Hall et al.
patent: 4030860 (1977-06-01), Standlick
patent: 4105373 (1978-08-01), Calzolari
patent: 4490096 (1984-12-01), Box
Basichas Alfred
Bertsch Richard A.
Putzmeister-Werk Maschinenfabrik GmbH
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