US 3749526 A
Pumping apparatus having a lubricating oil pumping circuit including a pump therefor and means for reversing the direction of flow, either means for reversing the pump or a reversing valve. The lubricating oil is pumped into or out of a pair of tanks, each divided into two chambers by a bellows and the oil being received by one of said chambers. The other of the chambers in each tank is part of a separate insulating oil circuit and by virtue of contraction and expansion of the bellows, pumps the insulating oil through check valves into a cable, compensating insulating oil being supplied from a storage tank through check valves to the other chambers and excess insulating oil being returned to the storage tank through an over pressure valve.
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Description (OCR text may contain errors)
Ferrentino PUMPING APPARATUS WITH TWO SEPARATED FLUID SYSTEMS  lnventor:
 Assignee: Industrie Pirelli Soeiete per Azioni,
Milan, Italy  Filed: May 20, 1971  Appl. No.: 145,421
Antonio Ferrentino, Monza, Italy  Foreign Application Priority Data May 23, 1970 ltaly 25004 A/70 52 U.S. Cl. 417/390, 417/394 51 Int. Cl. F04b 9/08, F04b 17/00, F04b 35/00  Field of Search 417/38, 40, 122,
1451 July 31, 1973 12/1962 McIntyre 417 390 x 8/1964 Eames et al. 417 307 x Primary Examiner-Charles J. Myhre Assistant Examiner-Frank H. McKenzie, Jr. AttorneyBrooks, Haidt & Haffner 5 7 ABSTRACT Pumping apparatus having a lubricating oil pumping circuit including a pump therefor and means for reversing the direction of flow, either means for reversing the pump or a reversing valve. The lubricating oil is pumped into or out of a pair of tanks, each divided into two chambers by a bellows and the oil being received by one of said chambers. The other of the chambers in each tank is part of a separate insulating oil circuit and by virtue of contraction and expansion of the bellows, pumps the insulating oil through check valves into a cable, compensating insulating oil being supplied from a storage tank through check valves to the other chambers and excess insulating oil being returned to the storage tank through an over pressure valve.
7 Claims, 2 Drawing Figures Patented July 31, 1973 Co/yrroL fin v awru/ /2 O M R w Z E g m NF A M Y B PUMPING APPARATUS WITH TWO SEPARATED FLUID SYSTEMS The present invention relates to a pumping plant especially, but not exclusively, suited for use in feeding oil-filled cables, and which permits the pumps operation in a lubricating oil circuit separate from the cable oil circuit.
When large quantities of oil are involved, the feeding of oil-filled cables is carried out mainly by pumping plants in which the pump is the most important and delicate part. Technical progress in the field of oil-filled cables has led to a preference for increasingly thinner types of insulating oils which therefore have proportionately fewer lubricating properties. This has meant that the operation of the pumps has become increasingly critical both with respect to the considerable friction which is created in the areas subject to rubbing, and because it is difficult to achieve a good seal on rotating parts which are in contact with non-lubricating oils.
The object of the present invention is to eliminate the above mentioned disadvantages by creating a pumping plant capable of keeping the two circuits of lubricating and insulating oils separate, thus permitting the satisfactory operation of the pump parts and a perfect seal in the insulating oil circuit.
Although the present invention is especially adapted for use in feeding oil-filled cables, it is also useful for the pumping of other fluids which have to remain separate from the lubricating oil and from the pump parts, as is the case when quantities of a liquid or gas with corrosive properties have to be moved.
More explicitly, the present invention concerns a pumping plant, especially suited for use in feeding oilfilled cables, comprising at least one pump operating, either directly or by means of an intermediate device, in such a way as to reverse its flow between inlet and outlet ports, characterized by the fact that it is fitted with at least two pressure tanks, each connected to a duct on the pump and divided into two chambers by a bellows-type expanding diaphragm closed at the top by a suitable lid, so as to separate the lubricating oil circuit including at least the first chamber of each pressure tank from the sealed circuit of insulating oil including the second chamber of each pressure tank, the second chamber being connected to the cable by means of a check valve and the insulating oil in the second chamber of each pressure tank being maintained by oil coming from a tank through a check valve.
The attached drawing illustrates, as a non-limiting example of the preferred embodiments of a pumping plant according to the invention, and in the drawing:
FIG. I is a schematic diagram of one embodiment using a uni-directional pump and a distributing valve for reversing the flow of fluid to and from the tanks; and
FIG. 2 is a fragmentary schematic diagram of a second embodiment using a reversible pump for reversing the flow of fluid to and from the tanks.
The pumping plant illustrated is intended for the feeding of fluid to a unit, in this specific case a cable 18, and comprises a pump 1, operated by a motor 2 and connected by ducts 20 and 21 to a distributing valve 3, controlled by first and second solenoids 4 and 5. Each duct 20 and 21 connects by the way of the valve 3 and the ducts 22 and 23 to ports in first pressure tank 6 and a second pressure tank 6'.
The first pressure tank 6 and the second pressure tank 6' are identical, and each comprises a first chamber 7 and 7' and a second chamber 8 and 8', separated the one from the other by a bellows-type expanding diaphragm 9 and 9', preferably of stainless steel, closed at the top by a suitable horizontal lid 10 and 10' of the same material. The horizontal lids l0 and 10' carry on the inside of the chambers 8 and 8 magnets l 1 and l l for activating magnetic switches 12 and 12, preferably of a sealed type, also within the chambers 8 and 8 and mounted on the walls opposite the lids l0 and 10'. Preferably, the switches 12 and 12 are of the reed type which comprises two foils extending from opposite ends of a glass bulb, one being fixed and the other being very light and movable. In the normal, or rest, position, the two foils are not touching but when a magnet is close thereto, the movable foil comes into contact with the fixed one, thus establishing continuity in the corresponding electrical circuit.
The switches 12 and 12' are connected, respectively, to the solenoids 4 and 5 which operate the valve 3. The system comprising the magnets 11 and 11', the switches 12 and 12' and the valve 3 with its solenoids 4 and 5 forms a device which can serve both as a flow reverser and as a limit switch. It will be apparent to those skilled in the art that such a system can be accomplished in a different way from that described. For example, the switches could be mounted externally of the tanks adjacent a non-magnetic wall of the tanks, the magnets being moved adjacent such wall and the switches by movement of the diaphragms.
The second chambers 8 and 8' of the pressure tanks 6 and 6' are connected via the filler ports 13 and 13' and check valves 14 and 14' to a cable 18.
The bellowstype diaphragms 9 and 9', with the respective lids l0 and 10 separate the lubricating oil circuit with respect to the sealed circuit of insulating oil. The first circuit extends substantially from the first chamber 7, through the valve 3, the pump 1, the valve 3 once more, to the first chamber 7', and with such a circuit one has the advantage that the pump 1 and the valve 3 can operate in the type of lubricating oil most suited to their performance, without critical conditions, regardless of the type of liquid being pumped in the second circuit.
The second circuit, or insulating oil circuit, is sealed against external contamination and extends from the second chamber 8 through the check valves 14 and 14', the cable 18, a tank 19, check valves 15 and 15' and to the second chamber 8'. A maximum pressure valve 16 can put the two check valves 14, 14' and the cable 18 in circuit with the tank 19. The motor 2 is controlled by a pressure switch 17 adjusted to the maximum and minimum pressure values permissible in the cable.
As an example of the operation, assume the pump 1 is operating and the valve 3 is set to supply oil to the pressure tank 6. The lubricating oil pushed into the first chamber 7 presses against the lid 10 of the bellows-type diaphragm 9 which therefore acts (the same applies to the diaphragm 9') only as a separating element between the lubricating fluid and the insulating fluid, without being subjected to any substantial pressure differences between its internal and external surfaces, thereby providing the advantage of extending its life to the maximum. The lid 10 compresses the bellows-type diaphragm 9 and moves, from the chamber 8 to the cable 18, through the filler l3 and the check valve 14, a quantity of insulating oil equal to the quantity of lubricating oil which has entered the chamber 7.
Simultaneously, the lubricating oil is pulled from the first chamber 7 of the pressure tank 6' expanding the second chamber 8' of said pressure tank 6', and an identical quantity of insulating oil is taken, in compensation, into the chamber 8' from the tank 19 through the check valve During these transfers of oil, the diaphragm 9' expands, while the diaphragm 9, as mentioned above, contracts. When the control magnet 11 moves into line with the reed type magnetic switch 12, the solenoid 4 control circuit is closed which reverses the position of the valve 3. In this new position, the oil is removed from the pressure tank 6 and sent to the pressure tank 6'. A similar magnet 11 acts on the reed type magnetic switch 12' when the diaphragm 9' has contracted to the predetermined point, thereby energizing the solenoid 5 and again reversing the valve 3.
The switches 12 and 12 act not only as flow reversers between the two pressure tanks 6 and 6' but also as limit switches for the diaphragms 9 and 9 to avoid damaging overexpansion of such diaphragms.
The pumping plant operates automatically, the pressure switch 17 being set at a minimum pressure ,p and a maximum pressure p permissible in the cable 18. Therefore, if the pressure in the cable were to go below the value p,, the pressure switch 17 would start the motor 2 which actuates the pump I, and would stop it as soon as the pressure in the cable reached the value If the oil in the cable 18 were to expand due to possible thermal expansions and its pressure reached a value 1 greater than p in the cable 18, the maximum pressure valve 16 would open which would permit the excess insulating oil to return to the tank 19.
The lubricating oil pumping devices can be different from those shown in FIG. 1. For example, a pump which can reverse its flow can be used, in which case the valve 3 would be omitted and the two pump ducts 20 and 21 are connected directly to the pressure tanks 6 and 6' as indicated in FIG. 2. In this embodiment, the switches 12 and 12 control a motor reverser, or direction control, 24 connected to reverse the direction of rotation of the motor 2 and consequently that of the pump 1, with theresult that the direction of lubricating oil flow to and from the tanks 6 and 6' is reversed directly by the pump 1.
It will be recognized by those skilled in the art that the constructional details of the invention can be varied according to particular requirements while utilizing however the principles of the invention.
What is claimed is:
l. Pumping apparatus comprising at least one pump for pumping oil, said pump having first and second oil pumping ports, said pump pulling oil into one said port and expelling such oil out of the other said port under pressure, means for driving said pump, first and second pressure tanks, each said tank having a bellows-type expanding diaphragm therein dividing the tank into first and second chambers, having an oil port for supplying oil to and removing oil from said first chamber and having a further port for supplying fluid to and removing fluid from said second chamber, closed, pressure duct means connecting said pump ports to the oii ports of said first and second tanks to provide a closed pumping circuit between said pump ports and said oil ports whereby oil is pulled out of the first chamber of one said tank by said pump when oil is pumped under pressure into the first chamber of the other said tank, one said pump port being connected to one said oil port and the other said pump port being connected to the other said oil port, means for reversing the direction of flow of the oil between said pump ports and the oil ports of said tanks to thereby change the pulling of oil out of said first chamber of said one tank by said pump to the supply of oil under pressure thereto and change the supply of oil under pressure to said first chamber of said other tank to the pulling of oil out of said latter chamber by said pump, a pair of first check valves, one
connected to the further port of said first tank for delivering fluid from said second chamber of said first tank to a receiver of said fluid and the other connected to the further port of said second tank for delivering fluid from said second chamber of said second tank to said receiver, a source of said fluid, a pair of second check valves, and closed, pressure duct means connecting one of said second check valves between said further port of said first tank and said source of fluid for supplying said fluid from said source thereof to said second chamber of said first tank and connecting the other of said second check valves between said further port of said second tank and said source of fluid for supplying said fluid from said source to said second chamber of said second tank.
2. Pumping apparatus as set forth in claim 1 wherein said means for reversing the direction of flow of oil between said pump ports and said oil ports comprises a distributing valve connected between said pump ports and said oil ports for alternately connecting said one pump port through closed duct means to the oil port of said first tank and said other pump port through closed duct means to the oil port of said second tank and vice versa. 1
3. Pumping apparatus as set forth in claim 2 wherein said distributing valve comprises electrically operable means for operating said valve and thereby reversing the direction of flow of the oil and further comprising first switch means in circuit with said electrically operable means and operable with movement of the diaphragm in said first tank to a predetermined position to change said distributor valve from a first position in which one of the alternate connections is provided to a second position in which the other of the alternate connections is provided, and second switch means in circuit with said electrically operable means and operable with movement of the diaphragm in said second tank to a predetermined position to return said distributing valve to its first position.
4. Pumping apparatus as set forth in claim 3 wherein said switch means comprises a pair of magnetically operable reed switches, one mounted in said second chamber of said first tank and one mounted in said second chamber of said second tank, and a first magnet carried by the diaphragm of said first tank and movable thereby to a position in which it operates the reed switch in the second chamber of said first tank when said diaphragm reaches a predetermined position and a second magnet carried by the diaphragm of said second tank and movable thereby to a position in which it operates the reed switch in the second chamber of said second tank when said last-mentioned diaphragm reaches a position corresponding to said predetermined position of said diaphragm in said first tank.
5. Pumping apparatus as set forth in claim 1 wherein said means for reversing the direction of flow of oil between said pump ports and said oil ports comprises means for reversing the direction of pumping of said pump controlled in accordance with the positions of the diaphragms in said tanks.
6. Pumping apparatus as set forth in claim 1 wherein said receiver is an electric cable and said fluid is an oil different from said first-mentioned oil and further comprising a pressure switch connected to the outlets of said first check valves and to said means for driving said pump for starting said pump when the pressure of said fluid is below a first predetermined value and for stopping said pump when the pressure of said fluid exceeds a second predetermined value greater than said first predetermined value.
7. Pumping apparatus as set forth in claim 6 further comprising an over-pressure valve connected between the outlets of said first check valves and said source for permitting flow of fluid from said last-mentioned outlets to said source when the pressure of said fluid exceeds a value greater than said second predetermined value.