FIELD OF INVENTION

[0001] The present invention relates to a battery structure and more particularly to an apparatus for improved cell handling and protection for batteries of a hybrid vehicle.

BACKGROUND OF INVENTION

[0002] Conventionally electric/ Hybrid vehicles have co-allocated batteries interconnected by wires. These set of batteries are assembled to the slid-able frame assembly, which requires separate material handling devices to dismantle the carriage for^chaxging^dis,charging and also for replacement. In most vehicles these batteryjpack _ facilitates only on-board charging facility. Hence it is very tedious to replace or assemble new battery pack on to the to the battery carriage assembly of the vehicle. Such an arrangement for battery storage requires inter connection between the cells by means of soldered wires. There is no special structure for any cell separation.

[0003] Cell casing has only a single functionality that is to accommodate the cells. Also in such a battery storage arrangements, power wires are routed across the cells. The printed circuit board is made and fixed as a separate module outside the cell. Such an arrangement may or may not have a venting system but they are not waterproof and hence there is risk involved for moisture/water entry. Such a battery storage system does not comply with water sealing requirements. In addition, power line wiring runs out of the battery for which special and different routing arrangements are needed. For signal, line a set of wires are soldered which interconnect with other nodes of batteries and terminals due to which there is more risk of circuit failure.

SUMMARY OF THE INVENTION

[0004] To obviate the limitations of the background art, the present invention discloses a power system for cell protection and arrangement mechanism to achieve a compact battery module with multifunctional benefits such as accommodation for fuse, interconnecting members and gas venting slot. The individual cells are arranged within a cell separator, which performs functions of cell contact avoidance, restricting the cell thermal expansion, and efficient heat dissipation.

[0005] In the current invention, cell casing is designed for better cell accommodation with integrated space for fuses and short insulation. The current cell structure as disclosed safe guards the cell array. Bus bars are designed to connect and transfer voltages and high current without using soldering. PCB integration as disclosed in the current invention provides improved integrated single module packaging. Hence, a large space is vehicle is saved. Main fuse has been integrated with the cell separation structure in the battery casing and hence no separate fuse box is required. So the current invention provides better serviceability.

BRIEF DESCRIPTION OF DRAWINGS

Figure lillustrates a typical battery case.

Figure 2illustratesa the cell separating structure used in the battery case.

Figure 3 illustrates an individual cell.

Figure 4 illustrates the interconnect sheet used to maintain gap and connect the cell terminals.

Figure 5 illustrates the interconnect sheet.

Figure 6 illustrates the interconnect sheet and bus bar termination.

Figure 7 illustrates the cell separator.

DETAILED DESCRIPTION OF THE INVENTION

[0006] The current invention discloses a cell separation structure for a battery case of a hybrid vehicle with an inter connect tab which acts as primary connections (in parallel and series as per the requirement) with all other cell. This interconnect also act as individual fuse. Since, during operation, a lot of heat is also generated from the batteries, the current interconnect facilitates the gas escaping path. Cell separator provides a group of cells a room for themselves collectively and also for the individual cells. The individual cells are protectively isolated from another cell to avoid any direct contact. The cell separator is having the properties to act as thermal expansion barrier and fire barrier.

[0007] The Cell casing accommodates all parts such as cells separator, inter connects, bus bar, BMS PCB etc. Bus bars connect various signal and power lines without wires. BMS/PCB integration manages complete cell array for battery pack operation. The venting system releases the excess pressure build up during operation. Water sealing avoids undesirable water and dust entry. Power line En-moulding transfers power without high current lines. Signal line also called CAN Signal provide the health of each cell array during operation to the BMS system.

[0008] The inter-connect tab which act as primary connections (in parallel and series) with all other cell. This interconnect also act as individual fuse, during a short or excess current charge or discharge it fuses and save the pack from catastrophe. The various layouts of the interconnect facilitates the gas escaping path to the cell during thermal runaway. The inter connect ends are;designed in such.a.way to accommodate the connections using a standard terminal this avoids soldering in a signal line routing.

[0009] Cell separator provides a cell a room for itself, the isolates a cell for another cell in contact. Also this conducts heat from each cell and dissipates for better operation, in other words thermal runaway facilitation. Cell separator provides every cell with a "shrink fit" in order to avoid bulging of cell during operation.' Cell casing accommodates all parts such as cells separator, inter connects, bus bar, BMS PCB etc. It also facilitates the pressure relief passage to the cell during thermal runaway. This also insulates the cell from direct body short. The cell case with its reinforcements provides a robust safety from external shocks to the cells; it also facilitates various series and parallel interconnects routing. The ribs and the protrusion separate the case from external metal casing from direct short.

[00010] Bus bars for power and signal line routing are passed to the end by means of miniature bus bars. The bus bar is en-molded to the casing. The en-molded bus bars avoid soldering in the pack design. The PCB is integrated to the end cover by means of a special snap lugs/ fastened. The assembly is sequenced in such a way that PCB will be dismantled first in order to remove the cell array for the casing for a safety purpose. If the PCB is dismantled the active circuit is disconnected and becomes open and hence the possibility of cell shorting is totally avoided.

[00011] As shown in Figure 1, a battery case 1 is illustrated. A battery is a collection of many cells. In the current inventien,-the cells are placed inside this battery case using a dedicated cell separation structure which performs two functions. First, it maintains proper alignment of individual batteries and second it avoids direct contact between two adjacent cells. Both the above functions of aligning individual cells by maintaining gap between two adjacent cells and avoiding contact of two adjacent cells is very important because they are the main cause of fire or leakage which may lead to damage of the battery. The battery case 1 is provided with holes 2 for proper ventilation, cell separation structure 3 for proper alignment and maintaining of gap . between two individual cells. The battery case is also equipped with railings 4 and railing 5 for sliding the battery on a mating railing for easy removal and replacement of the batteries.

[00012] The cell separation structure 3 has been more clearly illustrated in Figure 2. The cell separation structure is formed in two halves mainly the cell separator upper half 22 and the cell separator lower half 23. As illustrated the individual cells 21 are placed inside the cell holders of the cell separation structure.

[00013] Figure 3 shows the cell 21 with the cell terminal 31, cell lateral surface 33, and cell ring 32. Cell ring 32 may be used for providing grip between the cell . separation structure and the cell body for keeping the cell 21 in upright position.Moreover, the cell terminal 31 of all individual cells are connected in series or parallelas per the requirement for the charging or discharging process by help of a interconnect sheet which also functions as a bus bar which has been dealt in and explained more in the Figure 4...

[00014] Figure 4 illustrates the apparatus for cell separation structure without showing the cell holder. Cell holder accommodates the plurality of individual cells 21. The interconnect sheet 41 connects terminals of atleast two cells and provides electrical connection with the bus bar terminal 401 and 402. The individual interconnect sheets may hold more than one cell, and as shown in the Figure one interconnect sheet is illustrated to hold six number of cells. The end points of the interconnect sheets bends - as end 41 and ends at terminal 43. All the similar terminals from the individual interconnect sheets 41 has a similar end 43 which is connected to the terminal 401 and 402 through a separate bus bar.

[00015] Figure 5 illustrates the interconnect sheet 41 in more detail. The interconnect sheet is provided with a cell terminal holding first groove 51 and cell separating second groove 52. And at the ends, the interconnect sheet is equipped with

terminals 43 for getting electrically connected to other interconnect sheets. Figure 6 illustrates the interconnect sheet 41 connected with the terminals 31 of the individual cells 21. Figure 6 also shows the gas venting zone 51, cell gap zone 52 and fusing zone 53.

[00016] Figure 7 illustrates the typical construction of the cell separator 3. Since the cell separator is-used in two halves, both the upper half 22 and lower half 23 are similar. The typical cell separator comprises of plurality of cell holders 71 and cell gap maintaining portion 72. The side profile of the cell separator 73 is given a curved shape so. as to mate witk.the other .celLseparator and thereby avoid the relative motion of two adjacent cell separators.

We claim:

1. A power system for a hybrid vehicle, the said power system comprising; an on board battery management system; a traction motor; wherein the said traction motor draws power from the said battery management system for its operation; a plurality of batteries (1) comprising of plurality of individual cells with terminal (31) for power tapping; characterized in that:' the said battery (1) further comprises of atleast one cell separator (3) with provision for holding plurality of individual cells (21) in a cell holder (71); and V the said terminal (31) of plurality of cells (21) being inter-connected through an interconnect sheet (41); the interconnect sheet (41) further connected to a power line (401, 402).

2. The power system, for a hybrid vehicle as Claimed in Claim 1 wherein cell separator (3) is formed in two halves namely first upper half (22)and second lower half (23).

3. The power system for a hybrid vehicle as Claimed in Claim 1 wherein the said battery (1) comprises of atleast one cell separator (3).

-4. The power system for a hybrid vehicle as Claimed in Claim 1 wherein the said battery (1) comprises of atleast one interconnect sheet (41).

5. The power system for a hybrid vehicle as claimed in Claim 1 wherein the said interconnect sheet (41), electrically connects terminals (31) of atleast two individual cells (21).
6. The power system for a hybrid vehicle as claimed in Claim 1 wherein the said power line (401) is connected to the positive terminal of the cells and the power line (402) is connected to the negative terminal of the cells and vice-versa.