Abstract:
A battery system for electric vehicles in which replenishment of the energy content of the batteries is accomplished by pumping liquids into tanks on the vehicles from pumps at service stations, similar to, and in a comparable time to, the filling of the tanks of conventional vehicles. The system also extracts used liquids, which have been depleted of energy content, from the vehicles and returns them to the service station where they are recharged for subsequent supply to other vehicles.

Description:
BACKGROUND OF THE INVENTION 
     Many attempts have been made to produce an electrically-powered vehicle using electric motors powered from rechargeable storage batteries. These vehicles have all suffered from the disadvantage that electrical recharging of the batteries takes considerable time, usually a matter of some hours, which shortcoming has rendered this type of vehicle commercially unsuccessful. This invention describes systems for organizing batteries for vehicle or other uses whereby they can be rapidly recharged. 
     BRIEF SUMMARY OF THE INVENTION 
     This invention provides a system whereby the batteries of electrically-powered vehicles or other electrically-powered devices may be recharged by filling tanks with liquids that may be dispensed from pumps at service stations, thus avoiding the time required for the electrical recharging of such batteries. The refilling of tanks from service station pumps is a procedure with which the general public is familiar, which fact will foster the acceptance of this invention as applied to electrically-powered vehicles by potential customers. Furthermore the filling of the tanks on the vehicles can be accomplished at any of a plurality of service stations thus permitting the vehicles to have unlimited range of operation. 
     In addition this invention provides a system for use with electrically-powered vehicles which releases no exhaust substances into the environment by providing that the energy-containing liquids, having been used in the batteries and thereby having been depleted of their energy content, may be retained in tanks on the vehicles from which they may be removed at any of a plurality of service stations at which their energy content can be restored in batteries to which a source of electrical power is supplied, the liquids thereby being recharged to a state suitable to be used to fill the tanks of other electrically-operated vehicles. There is thus a closed cycle in which the liquids are (1) supplied to tanks on the vehicles, (2) used to provide energy to the batteries which power the vehicles, (3) stored after use on the vehicles, (4) removed from the vehicles at service stations, (5) charged with energy by electrical means, (6) resupplied to other vehicles. The operation of this invention is thus conducted without release of chemical substances into the environment. 
     The batteries to which this invention relates are such that the storage of energy is accomplished solely by changes in the chemical states of liquid electrolytes, the electrodes being unchanged as between the charged and discharged conditions of the battery, said electrodes serving solely to provide electrical contacts to the electrolytes. Such batteries are well known and go by the names of ‘redox flow cell’, or ‘regenerative fuel cell’. U.S. Pat. Nos. 3,996,064; 4,485,154; 5,318,865; and 5,612,148 disclose examples of such batteries and methods of construction thereof. The batteries described in these patents are recharged electrically. U.S. Pat. No. 4,127,701 discloses a battery having a replaceable liquid electrolyte and an oxidizable metal stack which must periodically be replaced. The construction of the batteries forms no part of the present invention, which relates to systems for their use. 
     This invention is not restricted to use in conjunction with electrically-powered vehicles. The novelty of this invention consists in the recharging of batteries by the physical transfer of electrolytes from previously charged batteries, and the ability to thus recharge any of a plurality of discharged batteries by physical transfer of electrolytes from any of a plurality of previously charged batteries. The invention may be applied to any situation in which this is advantageous. Accordingly this invention may be used with any electrically-powered device operating from batteries where it is required that the time needed to replenish the energy content of a discharged battery should be minimal. For example, portable battery-operated electric power tools, golf carts, forklift trucks, and powered wheelchairs for the disabled. Other examples will be apparent to those skilled in the art. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 shows one form for the implementation of this invention in an electrically-powered vehicle or other electrically-powered device. 
     FIG. 2 shows another form in which the invention may be implemented in an electrically-powered vehicle or device. 
     FIG. 3 shows yet another form in which the invention may be implemented in an electrically-powered vehicle or device, this being the preferred form. 
     FIG. 4 shows one form for the implementation of the charging aspect of this invention at a service station or other charging battery facility. 
     FIG. 5 shows the preferred form for the implementation of the charging aspect of this invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following description the batteries which are used to supply power to loads are referred to as energizing batteries, and the batteries which are used to store energy obtained from external sources of electrical power are referred to as charging batteries. According to this invention said energizing batteries are recharged by physical interchange of liquid electrolytes with said charging batteries, without need for electrical connection between the charging batteries and the energizing batteries or between external sources of electrical power and the energizing batteries. The invention is orientated toward the provision of rapid recharging capability for electrically-powered vehicles and this usage will be emphasized in this description. The invention is not limited to vehicle use, it is also applicable to any rechargeable-battery powered electrical device. Accordingly the phrase “vehicles or devices” is employed in the following description to include such other usages. 
     This invention seeks to accomplish the objects listed above by providing a system whereby the batteries on the vehicles or devices constitute ‘energizing batteries’ as defined above, and separate stationary ‘charging batteries’ also as defined above, are provided at service stations. In said charging batteries the chemical conditions of liquid electrolytes are changed by passage of an electric current to the conditions that obtain in a charged battery. The electrolytes are then transferred to the energizing batteries on the vehicles or devices, from which the previous electrolytes have been removed, which batteries are then in a charged condition ready to power the vehicles or devices. The electrolytes which had been removed from the energizing batteries are transferred to the charging batteries in which their chemical conditions are restored to the charged state. This recharging process may take an extended time without delaying the use of the vehicles or devices. 
     The batteries employed in the implementation of this invention are of a type known as ‘redox flow cells’. Such batteries are known art and do not form a part of this invention, however to assist in understanding the operation of this invention a brief description of the redox (reduction-oxidation) cell is given here. Essentially the cell employs two electrolytes, separated by a membrane which is permeable only to ions that are common to both electrolytes. The electrodes are chemically non-reactive, for example graphite. 
     When such a cell is charged by passage of an electric current, the anode electrolyte is reduced and the cathode electrolyte is oxidized. Positive ions pass through the membrane to restore the chemical and electrical balance. On discharge, the anode electrolyte is oxidized and the cathode electrolyte is reduced. Again the positive ions pass through the membrane. The motion of positive ions conveys the electric current through the cell. The cells may be so constructed that the electrolytes may be supplied to the cells as needed for the reactions so that a larger quantity of electrolytes than can be accommodated in a cell at any one time may be subjected to the charging or discharging reactions. In this the redox flow cell differs from other types of cell in that the total energy capacity of the cell is determined by the total quantity of electrolytes, which may be stored external to the cell and supplied to it and removed from it in an ongoing process. The size of the cell itself determines the power output or charging rate of the cell. 
     As is normal, a plurality of cells electrically connected is referred to as a battery and this term is employed with this meaning in this application. 
     With the preceding explanation in mind the operation of this invention can now be described. The invention requires a charging battery or plurality of same, and an energizing battery or plurality of same, separate and distinct from the charging battery or batteries. 
     Referring to FIG. 1, at  11  is shown a tank which contains a supply of the anode electrolyte, in its charged (reduced) state, and at  16  is shown a tank containing a supply of the cathode electrolyte, also in its charged (oxidized) state. Pumps  13  and  18  draw supplies of the electrolytes from the tanks through pipes  12  and  17  and deliver them to the energizing battery  1  through pipes  7  and  8 . Battery  1  is of the type already discussed. Its internal operation is not part of this application, but it should be understood that pipes  7  and  8  deliver the electrolytes to all cells of which the battery is composed. 
     The cells comprising the battery are internally electrically connected, the end cells being connected to terminals  2  and  3  from which current may be drawn through wires  4  and  5  to supply to load  6 , which may be the driving mechanism of an electrically-propelled vehicle, or any other electrically powered device. 
     As previously explained, the electrolytes are supplied to the battery as needed and, having undergone the chemical reactions which produce the electrical output, they are removed to permit fresh electrolytes to enter the battery. In FIG. 1 the electrolytes exit the battery through pipes  9  and  10  and are supplied by pipes  22  and  26  to tanks  21  and  25  which contain the used (oxidized) anode electrolyte and used (reduced) cathode electrolyte respectively. Since the battery remains filled the action of pumps  13  and  18  forces the used electrolytes to exit. 
     Tanks  11  and  16  are provided with filler pipes  14  and  19 , which are normally closed by caps  15  and  20 . Tanks  21  and  25  are provided with drain pipes  23  and  27 , also normally closed by caps  24  and  28 . These filler and drain pipes permit connection to the supply and extraction hoses of a charging battery system at a service station, such as, but not restricted to, those described with relation to FIG.  4  and FIG.  5 . 
     In FIG. 2 is shown an alternative approach to the implementation of the invention as regards the energizing battery. In this approach only one tank is required for each of the electrolytes, which are recirculated through the battery. As in FIG. 1, tanks  11  and  16  contain anode and cathode electrolytes respectively, pumps  13  and  18  draw electrolytes from these tanks by way of pipes  12  and  17 , and supply them to battery  1  through pipes  7  and  8 . Current is drawn from terminals  2  and  3  through wires  4  and  5  to supply to load  6 . Electrolytes exit the battery through pipes  9  and  10  but, in distinction to FIG. 1, they are returned to their original tanks through pipes  31  and  32 . 
     Tanks  11  and  16  are provided with filler pipes  14  and  19 , which are normally closed by caps  15  and  20 . They are also provided with drain pipes  23  and  27 , also normally closed by caps  24  and  28 . As in the system of FIG. 1, these filler and drain pipes permit connection to the supply and extraction hoses of a charging battery system, such as, but not restricted to, those of FIG. 4 or FIG.  5 . 
     The approach as shown in FIG. 2 has the advantage that only a single tank is required for each electrolyte, as compared with the source and drain tanks shown in FIG.  1 . These source and drain tanks can each be required to hold the full volume of electrolyte and must therefore be of similar capacities. In the approach of FIG. 2 a single tank takes the place of two tanks of similar size, thus the overall volume of the tanks required is halved. This reduction in space occupied by tanks is of advantage in mobile uses of this invention, particularly as applied to vehicles. Repeated recirculation of the electrolytes may also result in more complete extraction of their energy content, by allowing oxidation or reduction of those components of the electrolytes which had not been so converted on first passage through the battery. 
     However, with the single tank per electrolyte approach shown in FIG. 2, it is necessary to drain the electrolyte from a tank before it can be filled with fresh (charged) electrolyte. Hence to extract all the available energy contained in the electrolytes, the battery must be operated until no more energy can be obtained, after which the tanks can be drained and refilled. To drain and refill before all available energy has been extracted would result in the loss of energy that could possibly have been obtained. In a commercial usage this would be undesirable. However, when used in an electrically powered vehicle, it is also undesirable to expect the operator to continue driving until the energy supply is exhausted, wherever the vehicle may be, or sacrifice energy that could have been used and for which payment has been made. 
     In the approach shown in FIG. 3 one possible solution to this problem is depicted. In this approach there are two tanks for each electrolyte, denoted as “A” and “B”, which are used alternately. To avoid occupying more space in the vehicle the total capacity of the anode electrolyte tanks may be similar to that of the anode electrolyte tank shown in FIG. 2, and likewise for the cathode electrolyte tanks, however this is optional. The sizes of the “A” and “B” tanks may be similar or different. 
     In FIG. 3 tanks  11  and  41  comprise the anode electrolyte “A” and “B” tanks, and tanks  16  and  46  comprise the cathode electrolyte “A” and “B” tanks, respectively. Valves  35 ,  36 ,  37 , and  38  permit selection of one or other anode tanks and one or other cathode tanks. Pump  13  draws anode electrolyte from tank  11  or tank  41  by way of valve  35  and pipes  12  or  42 , and supplies this electrolyte to battery  1  through pipe  7 . Similarly, pump  18  draws cathode electrolyte from tank  16  or tank  46  by way of valve  37  and pipes  17  or  47 , and supplies it to battery  1  through pipe  8 . 
     As in the example of FIG. 1, the end cells of the battery are connected to terminals  2  and  3  from which current may be drawn through wires  4  and  5  to supply to load  6 . Electrolytes exit the battery through pipes  9  and  10 , and, as in the approach of FIG. 2, they are returned to their original tanks. Valves  36  and  38  are operated in conjunction with valves  35  and  37  respectively so that the electrolytes are returned to the tanks from whence they came, through pipe  31  or  51  for the anode electrolyte, and pipes  32  or  52  for the cathode electrolyte. 
     Tanks  11 ,  16 ,  41  and  46  are provided with filler pipes  14 ,  19 ,  44  and  49 , normally closed by caps  15 ,  20 ,  45  and  50  respectively, and with drain pipes  23 ,  27 ,  53 , and  57 , also normally closed by caps  24 ,  28 ,  54  and  58  respectively, which permit connection to the supply and extraction hoses of a charging battery system, such as, but not restricted to, those of FIG. 4 or FIG.  5 . 
     It will be apparent that a vehicle or other device powered by a battery using the approach shown in FIG. 3 may be operated with the valves set such that the “A” tanks, that is tanks  11  and  16 , are in use, until such time as the total energy content of these tanks has been extracted, whereupon changeover to the “B” tanks (tanks  41  and  46 ) may be made, and operation continued. At a convenient time thereafter, the “A” tanks may be recharged by exchange of the discharged electrolytes for electrolytes that have been charged in a charging battery at a filling station. 
     Operation continues until the “B” tanks in turn have been depleted of energy, whereupon changeover to the “A” tanks is made and the “B” tanks are subsequently recharged by exchange of electrolytes at a filling station. Thus continuing operation is possible without need to drain a tank the electrolyte in which still contains available energy. 
     In FIG. 4 is shown a simplified approach to the implementation of the invention as regards the charging battery. The charging battery performs the complementary operations to the energizing batteries already discussed, that is, it takes discharged (oxidized) anode electrolyte and discharged (reduced) cathode electrolyte and converts them to the charged state by passage of an electric current which reduces the anode electrolyte and oxidizes the cathode electrolyte. In principle the charging battery is analogous to the energizing battery with the difference that a source of direct-current electrical power replaces the power-consuming load. 
     Referring to FIG. 4, at  11  is shown a tank of discharged anode electrolyte and at  16  a tank of discharged cathode electrolyte. Pump  13  draws electrolyte from tank  11  through pipe  12  and supplies it to battery  1  through input pipe  7 . Similarly, pump  18  draws electrolyte from tank  16  through pipe  17  and supplies it to battery  1  through input pipe  8 . A source of d.c. electric power  66  supplies current to battery  1  through wires  4  and  5  and terminals  2  and  3 . The electrolytes leave the battery through exit pipes  9  and  10  which supply them to tanks  21  and  25  through filler pipes  22  and  26 . 
     Tank  11  is provided with a filler pump  61  which has an input pipe  62  with a flexible hose  63  having a connector  64  suitable for attachment to the drain pipe of an anode electrolyte tank associated with an energizing battery, such as drain pipe  23  of FIG. 1 or FIG. 2, or drain pipes  23  or  53  of FIG.  3 . Likewise tank  16  has a filler pump  65  with input pipe  67 , flexible hose  68 , and connector  69  suitable for connection to drain pipes such as  27  of FIG. 1 or FIG. 2, or  27  or  57  of FIG.  3 . 
     Tanks  21  and  25 , which store the charged anode and cathode electrolytes respectively, are similarly provided with pumps  71  and  75  having output pipes  72  and  77 , with flexible hoses  73  and  78  which are equipped with nozzles  74  and  79 , which are suited to inputting the electrolytes into the filler pipes of tanks associated with energizing batteries, such as pipes  14 ,  19 , of FIG. 1 or FIG. 2, or pipes  14  or  44 ,  19  or  49 , of FIG.  3 . 
     The operation of this invention can now be understood by considering the working of FIG. 4 in conjunction with any of the schemes depicted in FIG. 1, FIG. 2, or FIG.  3 . Direct current electrical power is employed to charge electrolytes in battery  1  of FIG.  4 . The charged electrolytes are subsequently physically transferred to the tanks supplying the energizing batteries as depicted in FIG. 1, FIG. 2, or FIG. 3, while the used, that is discharged, electrolytes from said energizing batteries are recovered and transferred into the tanks which supply the charging battery, such as battery  1  of FIG.  4 . 
     The configuration of tanks shown in FIG. 4 is shown to assist in understanding the invention and, while theoretically operable, is not the preferred implementation of the charging battery functions. It will be appreciated that, using the arrangement of FIG. 4, it would be necessary to complete the charging of the electrolytes before storing them in the charged electrolyte tanks, in order that the electrolytes transferred to the energizing batteries should be fully charged. 
     In FIG. 5 is shown a preferred approach to the implementation of the charging battery functions. FIG. 5 resembles FIG. 4 to the extent that at  11  there is a tank of discharged anode electrolyte and at  16  a tank of discharged cathode electrolyte. Pump  13  draws electrolyte from tank  11  through pipe  12  and supplies it to battery  1  through input pipe  7 . Similarly, pump  18  draws electrolyte from tank  16  through pipe  17  and supplies it to battery  1  through input pipe  8 . Direct current electric power source  66  provides current to battery  1  through wires  4  and  5  and terminals  2  and  3 . The electrolytes leave the battery through exit pipes  9  and  10 . However at this point FIG. 5 differs from FIG. 4 in that the electrolytes are returned to the tanks  11  and  16 , through pipes  31  and  32 , thus being continually recirculated through the battery. 
     After a time sufficient for the electrolytes in tanks  11  and  16  to become fully charged, pumps  87  and  97  are activated, transferring electrolytes from tanks  11  and  16  to tanks  85  and  95  by way of pipes  86  and  96 . The electrolytes may be retained in the latter tanks until such time as they are required to refill the tanks associated with an energizing battery such as tanks  11  and  16  of FIG. 1 or FIG. 2, or tanks  11  or  41 , and  16  or  46  of FIG.  3 . It will thus be apparent that the configuration of FIG. 5 constitutes an energy storage system; the charged energy-containing electrolytes being stored in tanks  85  and  95  until needed. Voltage measuring means  100  may be connected between the terminals  2  and  3  of battery  1  to provide indication of the state of charge of the electrolytes to inform when operation of pumps  87  and  97  should be initiated. 
     When electrolytes are withdrawn from tanks  11  and  16  by pumps  87  and  97 , the filling pumps  83  and  93  are also activated. These draw discharged electrolytes from tanks  81  and  91 , by way of pipes  80  and  90 , and deliver them to tanks  11  and  16  by way of pipes  14  and  19 . Tanks  11  and  16  are thus kept continually filled. 
     Tank  81  is filled with discharged anode electrolyte, and tank  91  with discharged cathode electrolyte, obtained from an energizing battery such as those depicted in FIG. 1, FIG. 2, or FIG.  3 . This action will normally take place at the same time as the tanks associated with the energizing battery are being filled from tanks  85  and  95 , so that the discharged electrolytes from the energizing battery are replaced with charged electrolytes. 
     To perform these transfers of electrolytes to and from the energizing battery, pumps  61 ,  71 ,  65 , and  75  are activated. Pumps  61  and  65  have input pipes  62  and  67  with flexible hoses  63  and  68  having connectors  64  and  69  suitable for attachment to the drain pipes of the electrolyte tanks associated with an energizing battery, such as drain pipes  23  and  27  of FIG. 1 or FIG. 2, or drain pipes  23  or  53  and  27  or  57  of FIG. 3, thereby transferring the discharged electrolytes from the tanks related to the energizing battery to tanks  81  and  91  through filler pipes  82  and  92 . Pumps  71  and  75  draw electrolytes from tanks  85  and  95  and supply them to output pipes  72  and  77  fitted with flexible hoses  73  and  78  having nozzles  74  and  79  suitable to inputting the electrolytes into the filler pipes of tanks associated with energizing batteries such as pipes  14 ,  19 , of FIG. 1 or FIG. 2, or pipes  14  or  44 ,  19  or  49 , of FIG. 3, thus filling the tanks connected to the energizing battery with charged electrolytes. 
     In the preceding description it has been assumed that two electrolytes are transferred between the charging batteries and the energizing batteries. However this invention is not to be considered as restricted to the transfer of two, and only two, fluids. For example U.S. Pat. No. 5,612,148 describes a cell having a buffer chamber interposed between the positive and negative chambers of the cell through which an idler electrolyte circulates. The principles of this invention may also be used to transfer three fluids between the charging and energizing batteries. 
     While in the preceding description approaches to the implementation of this invention have been set forth, this preceding description is not intended to be in any way restrictive or limiting of the embodiment of the invention. It will be apparent to those skilled in the art that many of the details described above can be varied without departing from the basic principles of the invention.