Pump drive apparatus This invention relates to pump drive apparatus for pump apparatus for pumping a slurry or the like to a solid-liquid separator such as a filter press.
Processing of a slurry such as a sludge has become a critical social problem with the progress of various industries and large capacity high pressure pumps have become necessary for pumping various kinds of slurries. A pump having an expansible flexible membrane in place of a mere diaphragm pump has been developed and put into practical use as disclosed in many patent and utility model applications filed by the present Applicant. An oil pressure system to be used to drive such a pump has been developed and put into practical use, too.
In a large plant where the pump is connected to a filter press, or the like, a large oil pressure system is needed which is fixed. Demand has been increasing for a portable pumping apparatus which is simple in construction and is easy to operate. However, a compact oil pressure driven apparatus that satisfies such requirements has not yet been developed.
Pump drive apparatus of the oil pressure type has the problem that if needs a complicated controlling apparatus when the stroke of the piston is set at the initial stage. As a result, although they are portable, they are expensive and management control and maintenance are complicated.
According to the present invention there is provided a pump drive apparatus including three oil chambers in a pressure cylinder, a piston in each chamber, the pistons being connected by a connecting rod; the two outer chambers being connectable at their outer ends to the pressure chambers of respective pumps and being connected together at their nearer ends via a hydraulic by-pass passage, and the compartments on either side of the piston in the central chamber each being connected hydraulically via a switch valve to an oil pump and reservoir so that the pistons can be moved in alternate directions by application of pressurized oil to alternate sides of the piston in the central chamber.
The present invention can provide a pump drive apparatus which is compact in construction, can be set easily at the initial stage, employs a closed circuit for an oil pressure circuit, has less oil leakage, and can be easily connected to and disconnected from the pump.
A preferred embodiment of the invention will now be described by way of example with reference to the accompanying sole drawing which is an explanatory view of one embodiment of the present invention and a schematic structural view.
Reference numeral 1 represents a pump drive apparatus that is connectable to two pumps having housings 2. In each pump an expansible flexible membrane 3 made of rubber is disposed inside the housing and defines a slurry chamber 4 on one side. This slurry chamber 4 is selectively connected by a threeway changeover valve 5 to a filter press 9 through a passage 7, and to a slurry tank 8 through a passage 6, so that the slurry chambers 4 on both sides alternately suck and pump the slurry.
A support 10 which is slidable and expands and contracts the flexible membrane 3 is located inside each pump and is connected to the pump drive apparatus 1 through a passage 11.
Inside the pump drive apparatus 1, a pair of partitions 15, 15 are disposed between covers 14, 14 on both ends of the barrel 13 of an oil pressure cylinder 12 in such a manner as to separate a centre oil pressure chamber 16 and oil pressure chambers 17, 17 on both sides of it. Pistons 18 are slidably disposed in each of these oil pressure chambers 16, 17, 17 and are connected to each other via a rod 19 which passes through the partitions 15, 15 through respective seals. One piston 18 divides the centre oil pressure chamber 16 into two pressure chambers 20, 20. Each of the oil pressure chambers 17, 17 on either side is divided into an inner oil chamber 21 and an outer oil pressure chamber 22 and the inner oil chamber 21 is communicated with a bypass passage 24 through an opening 23 in the partition 15.
The outer pressure chamber 22 of each of the oil pressure chambers 17 on both sides is connected by an opening 25 to an oil tank 28 by a passage 27 that has a switch valve 26 such as an electromagnetic valve.
The pressure chamber 22 of each of the oil pressure chambers 17 on both sides is connectable to the oil pressure passage 11 of the pump 2 by a coupling 31 through an oil pressure passage 30 having a switch valve 29 such as an electromagnetic valve.
The pressure chambers 20, 20 on both sides of the centre oil pressure chamber 16 are communicated with oil pressure passages 33, 33 through ports 32, 32, respectively, and from thence with an oil pressure passage 35 through a changeover valve 34 and with the oil tank 28 through an oil pressure pump 36. Predetermined stroke sensors 38', 38' are disposed on the pair of partitions 15, 15.
Reference numeral 37 represents a controlling apparatus. This controlling apparatus 37 is connected to a sensor 38 for the flexible membrane 3 of each pump 2, the sensor 38' for the piston 18 disposed on the partition 15 of each oil pressure chamber 20, each switch valve 26, 29 such as the electromagnetic valve, the switch valve 5 and the switch valve 34 by respective cables in order to control them in a predetermined manner.
The mechanical portion of the pump drive apparatus represented by the two-dot-chain line can be mounted on and transported by a truck, for example, and can be connected and disconnected to and from a pair of pumps 2 juxtaposed with the filter press 9 of a predetermined slurry processing plant, or the like, through the oil pressure passage 11, 11.
As described above, after being transported by a truck or the like, the pump drive apparatus 1 is disposed between the pair of pumps 2, 2 in such a manner that the oil pressure passages 30, 30 of both oil pressure chambers 17, 17 can be coupled to the respective oil pressure passages 11, 11 through the couplings 31. In this state, the electromagnetic valve 29 of each oil pressure passage 30 is kept closed by the controlling apparatus 37 and the oil pressure chambers 22 of the oil pressure cylinder 12 do not communicate with the pumps 2.
In the connection state described above, each piston 18 does not generally reach the stroke end. Before use, each electromagnetic valve 26 is opened by the controlling apparatus 37 and the switch valve 34 is operated in a predetermined manner so as to pump the oil from the oil tank 28 through the oil pressure pump 36 to one of the pressure chambers 20 of the centre oil pressure chamber 16. Then, the oil of the other in the oil pressure chambers 20 is returned to the oil tank 28, and the piston 18 of the centre oil pressure chamber 16 moves towards one of the partitions 15 at a low speed from the middle of its stroke and reaches the sensor 38' at its stroke end.Meanwhile, the oil in one of the inner oil chambers 21, 21 of the oil pressure chambers 17, 17 moves to the other through the bypass passage 24 and the ports 23, 23 and a suction negative pressure is generated in the outer pressure chamber 22 of one of the oil pressure chambers 17. Oil from the oil tank 28 passes into that oil pressure chamber 22 through the electromagnetic valve 26 and the port 25, while the oil is fed back from the other pressure chamber 22 through the port 25 and the electromagnetic valve 26. At this state, the sensor 38' generates a stroke end signal and the controlling apparatus 37 changes over the switch valve 34 to the neutral position, thereby completing the initial set state.
Optionally, the electromagnetic valve 26 associated with the full oil pressure chamber 22 is then closed, and the associated valve 29 opened. The switch valve 34 is then operated to reverse the movement of the piston 18. Oil from the full oil pressure chamber 22 passes via valve 29 and passage 11 into the pressure chamber 9 of the pump 2, and oil is sucked into the other oil pressure chamber 22 from the tank 28 via the other, open valve 26. The sensor 32 again generates a stroke-end signal causing the switch valve to be put in the neutral position, and the second valve 26 is now closed and second valve 29 opened, thereby completing the initial setting-up.
In this initial set state, the slurry from the slurry tank 8 fills the slurry chamber 4 of one of the pair of pumps 2, 2 while the slurry chamber 4 of the other is kept empty. This state is achieved on the processing plant side.
The outer pressure chambers 22, 22 of the oil pressure chambers 17, 17 on both sides of the oil pressure cylinder 12 now communicate with the inner pressure chambers 9 of the flexible membranes 3 of the corresponding pumps 2. When the switch valve 34 is changed over at this time, oil is pumped into the other oil pressure chamber 20 in the centre oil pressure chamber 12 from the oil pressure passage 33 through the oil pressure pump 36, and each piston 18 moves. The oil pressure is reduced in the pressure chamber 9 of the flexible membrane 3 of one pump 2 which sucks the slurry into the slurry chamber 4, while a pressure develops in the oil pressure chamber 9 of the other pump 2, and the slurry from the slurry chamber 4 of the other pump 2 is pumped into the filter press 9 while the three-way valves 5, 5 are controlled by the controlling apparatus 37.The slurry from the slurry tank 8 is sucked into the slurry chamber 4 of the first of the pumps 2, and the sensors 38', 38' of the partitions of the oil pressure cylinder 12 detect the stroke end of the piston 18.
When the sensor 38 on the cover of the pump 2 detects the end of the swelling stroke of each flexible membrane 3, the controlling apparatus 37 changes over the switch valve 34 and hence, changes over pumping of the oil to thepressure chambers 20, 20 of the centre oil pressure chamber and the oil tank 28. Therefore, the oil pressure cylinder 12 operates and the pair of pumps 2, 2 are controlled in order to alternately pump large quantities of slurry from the slurry tank 8 into the filter press 9.
The oil of the inner oil chambers 21, 21 of the oil pressure chambers 17, 17 on both sides of the oil pressure cylinder 12 is alternately moved back and forth through the bypass passage 24.
When pumping of the slurry to the filter press 9 is completed in this manner, the pump apparatus is removed from both pumps 2, 2 through the couplings 31, 31 and is transported to the next processing plant by the truck.
It is of course preferred to keep the switch valve 34 at the neutral position during the transportation.
Since the oil circuit is kept as a closed circuit during the operation and transportation of the pump drive apparatus 1, leakage of the oil is much less likely to occur. However, when oil leakage occurs accidentally, the initial setting of the pump drive apparatus 1 can be accomplished reliably by the initial setting of the stroke with respect to the centre oil pressure chamber 12 at the initial stage as described previously.
The present invention is not particularly limited to the embodiment described above. For instance, lamps can be turned on and off at each stroke end of the piston.
The present invention can be applied not only to slurry processing plant but to the pumping of chemicals, water, and the like, and the rods of the oil pressure chambers on both sides can be of a double rod type from the aspect of design change.
In a pump apparatus for supplying operation oil to pumps for pumping a slurry to a solidliquid separator such as a filter press, the present invention can set the operation piston to the initial set position by use of the pump apparatus itself. Therefore, the present invention provides a pump apparatus which can be made transportable by a truck, or the like.
Since the pump apparatus has three oil pressure chambers, its construction is extremely simple, and can be set up by operating the switch valves with respect to the centre oil pressure chamber only, thereby reducing possible trouble and making maintenance and inspection extremely easy. When the pump drive apparatus is connected to the pump, its initial setting can be made easily and flexibly.
Since the oil passages of the oil pressure chambers on both sides are connected to the oil tank through the switch valves, the switch valves are opened at the initial state when the pump drive apparatus is being connected to the pumps. They are then closed whereby the alternate changeover operation of the pair of the pumps can be made in a reliable manner.
Since the apparatus can be made compact as a whole, it can be minimized within the possible limit of design and can be applied to a slurry processing apparatus of a small scale plant and to plants for preventing environmental pollution of other industrial fields.