FIELD OF INVENTION

[0001] The present invention relates to a battery pack assembly of a hybrid vehicle and more particularly to a casing-structure for the battery of a hybrid vehicle.

BACKGROUND OF INVENTION

[0002] Hybrid automobile require protection from entry of dust and water inside the battery pack; otherwise, it may harm the cells. The end covers which cover a battery at the two ends, most of the times do not provide enough sealing from water, dust etc. Hence, there is possibility of cell failure due to ^undesirable environmental effects such as water, dust or mud ingress inside the battery. Hence, due to the aforesaid undesirable environmental effects battery pack may be damaged.

[0003] Due to durability requirements, the outer casing of batteries is made up of metals. Since metals are good conductors of electricity, the electrical and mechanical protection of battery casing becomes a challenging task. Subsequently, since typical metals are heavy compared to plastics, due to this, such a metal casing adds to the weight of the cells and becomes heavy due to which insertion of batteries in the battery pack assembly structure becomes difficult. Also due to metal casing being heavy in weight, if not carefully inserted, it may lead to battery casing breakage. Also due to usage of wires for carrying current, probability of operational fatigue, physical damage of power line and failure due to short circuit increases.

[0004] The chemical reactions taking place inside the cells being exothermic in nature, produces a lot of heat energy due to which gas zones are created. Proper venting of these gases from the battery pack is very essential for protection of the cells within the battery. In absence of sufficient venting mechanism, battery pack failure may take place due to buildup of excessive pressure.

[0005] While inserting the battery into the battery pack assembly batteries must be inserted carefully so as the terminals are perfectly coupled to avoid damage of terminals and loose connections. Theft of battery pack is another possible threat as the batteries are exposed and proper-Jocking mechanism is absent. Hence,.a proper security system for the battery pack is desirable.

SUMMARY OF THE INVENTION

[0006] To obviate the problems associated with the background art, the present invention discloses a battery casing with a polymer seal that is shrunk and wrapped with a polymer sheet for dust and waterproofing. In another embodiment of the present invention, the plastic battery case is equipped with a series of steps placed along the battery casing surface, which prevents the cells from impact and guards the battery casing surface. In yet another embodiment of the present invention, the battery casing is provided with a venting mechanism for venting out the hot gases produced during operation of individual cells inside the battery.

[0007] In yet another embodiment of the invention, the end cover of the battery is provided with a handle grip provision. The grooves in it enable the fingers to hold the case firmly so that while placing and replacing the battery pack, the battery pack is held firmly in the handgrip and possibility of falling of the battery pack is minimized. In yet another embodiment of the current invention, the battery case is equipped with a Battery management system module (BMS module) which is digitally coupled to communicate with the corresponding controller of the vehicle. In this way, even when a battery pack is stolen and is tried to assemble with a different vehicle's controller, the battery pack will not communicate with the battery management system of the new vehicle.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 illustrates exploded view of a typical battery of a hybrid vehicle.

Figure 2 illustrates an individual cell.

Figure 3 illustrates terminal of an individual cell.

Figure 4 illustrates the exploded view of one end of a typical battery.

Figure 5 illustrates sealed and unsealed end of a typical battery. .

Figure 6 illustrates the seal at the rear end of battery attached to battery casing.

Figure 7 illustrates provisions for battery handling.

Figure 8 illustrates provisions for battery handling.

Figure 9 illustrates sealing mechanism under normal condition.

Figure 10 illustrates the venting mechanism during de gassing in battery.

Figure 11 illustrates the en-molded power lines in the proposed battery.

Figure 12 illustrates the en-molded battery terminal and power line in the proposed battery.

DETAILED DESCRIPTION OF THE INVENTION

[0008] The battery casing structure, as disclosed in the current invention has sealing provisions to inhibit water and dust entry inside the battery. In order to release the excess gas, a venting system is provided for pressure relief. The venting system consists of a polymer seal valve. The end cover of the battery has a slot to accommodate a free running shrink seal. The seal comprises of a shrinking sheet cover, which is stripped off after setting the seal in to the seal slot. The polymer seal expands and fills the slot after which end cover is assembled to the outer casing of the pack. This expandable shrink sealing method avoids water and dust entries and adheres to the environmental standards!

[0009]. The end cover of the battery as disclosed in the current invention comprises of power line en-moulded studs. Also, if a wire runs through the end cover of the battery, sealing would be a difficult problem and it would be very difficult to address

environmental compliances. The said studs are electrically connected to a port on BMS through en-molded power lines. This method of power transmission avoids lose wire routing within the battery and battery pack assembly. This mechanism of power transmission is more efficient and probability of battery pack failure due to power transmission related issues are minimized.

[00010] To obviate the problems associated with the background art, the present invention discloses a polymer seal which is shrunk and wrapped with a polymer sheet. Once the seal is placed in the slot (in the end cover of the battery) the shrunk sheet gets . unwrapped and fills in, with this expansion thereby a compressed, sealing .is.-pravided between end cover and metal casing.

[00011] In another embodiment of the present invention, the plastic battery casing is equipped with a series of steps placed at regular intervals on the battery casing outer surface. Bus bars are also en-molded with the battery casing. This avoids wire routing and soldering to be done in the battery casing. Power line studs are en-molded in the end cover facilitating better transmission efficiency and avoid the use of wires.

[00012] In yet another embodiment of. the present invention, the battery case is . provided with a venting system for pressure relief. A polymer seal valve is assembled to the end cover which enables pressure relief during excessive pressure built up and also prevents water, dust entry.

[00013] In yet another embodiment of the invention, the battery end cover is equipped with a provision for handle grip. The grooves in the handle grip enable the fingers to hold the case firmly so that while inserting and replacing the battery pack, the battery pack is held firmly and possibility of falling of the battery pack is minimized.

[00014] In yet another embodiment of the current invention, the battery case is equipped with a BMS module which is digitally coupled to communicate with the corresponding controller of the vehicle. An integrated electronic security system on BMS is unique to a particular pack, which cannot operate on different battery —-pack/vehicle systems, unless and until anew program-is fed* into-the security system. In this way, even when a battery pack is stolen and is tried to assemble on a different vehicle's controller, the battery pack won't communicate and thus won't give any power output.

[00015] Figure 1 shows an exploded view of a typical battery used in a hybrid vehicle. Figure 1 shows a battery case 1, cell terminals 2, cell interconnect casing 3, cell separator lower 4, cell separator upper 5 and battery cover 6. The battery casing holds the individual cells and the joint output of all the cells are transferred to a channel through bus bars. All the batteries being used in the hybrid vehicle are connected to a bus bar. The holding of individual cells, protection of casing due to changes in physical conditions inside the battery case and protection of individual cells so as electrical short circuit and failure of cells don't take place is an important aspect dealt by the structure of the battery casing. The cell separator upper 5 and cell separator lower 4 keep the cell in upright position and maintain constant distance between terminals of two adjacent cells.

[00016] Figure 2 illustrates an individual cell 20, cell lateral surface 21 and cell terminal ring 22.As explained in Figure 1, the cell lateral surface 21 is held by the cell separator upper and cell separator lower. The terminal 22 is held by the interconnect sheets44 which connects the terminals of a group of cells in the battery. Figure 3 illustrates terminal end of the individual cell with cell lateral surface 21 and cell terminal 31. The current arrangement prevents difference or loss in power rating due to cell array misplacement. Direct short of the,interconnect.cells.,.to the metal body or to each other can be avoided. Also, formation of heated zone between the cells is minimized due to maintaining of constant gap between adjacent cells.

[00017] Figure 4 illustrates the exploded view of one end of a typical battery. Figure 2 shows cell terminals 2, cell separator lower 4, battery end cover 41, sealing member 42, cover holes 43 and interconnect sheet 44. The sealing member 42 in-between the battery end cover 41 and the battery, body prevents entry of dust and various pollutants inside the battery and thus thereby protects the cell arrangement, terminals and the bus bars. Slots in the interconnect sheet 44 facilitates for gassing off. The holes 43 in the plastic casing facilitate the venting of the gases.

[00018] Figure 5 illustrates sealed and unsealed end of a typical battery to locate the sealing member on the rear end of the battery. The battery end cover 41 has a sealing member 42 placed over a flat mating surface, the flat mating surface overlaps the battery body and the end cover. A polymer seal is shrunk and wrapped with a polymer sheet. Once the seal is placed in the slot (in the end cover) the shrunk sheet is unwrapped and fills in, with this expansion. A compressed sealing is provided between end cover and metal casing of the battery body. Figure 5shows the end cover with and without the sealing member. Figure 6 illustrates the seal at the rear end of battery attached to battery casing. Figure 6 shows battery end cover 41, seal expansion rear end cover 61 and rear end cover 62.

[00019] Figure 7 and Figure 8 illustrates provisions for battery handling. Figure 7 shows battery end cover 41, firsLhandling,provision.Il, second handling provision 72 and a fuse 73 placement on the end cover. By using the handling provisions on front-end cover, the grooves in it enable the fingers to hold the case firmly and reduce the chances of slippage of the battery from user's hands. Hence, pack failure due to mishandling can be avoided. Since the fuse is placed on the end cover, replacing a fuse is very convenient.

[00020] Figure 9 illustrates sealing mechanism under normal condition. Figure 9 shows relief passage 91, silicone valve 92 and valve retainer 93. A venting system is provided for pressure relief. A polymer seal valve 92 is assembled to the end cover which enables pressure relief during excessive pressure built up and at the same time prevents entry of water, dust etc. inside the battery. Hence pack failure due to build up pressure can be avoided. Figure 10 illustrates the venting mechanism during de gassing in battery. Figure 10 shows "relief passage 91, gas flow direction 100, first gas movement route 101, and second gas movement route 102.

[00021] Figure 11 illustrates the en-molded power lines in the proposed battery. Figure 12 illustrates the en-molded battery terminal and power line in" the proposed battery with step sliding guide 111, en-molded power linell2 and en-molded power route 113. An integrated electronic security system 114 on BMS is unique to the particular pack, which cannot operate other pack/ vehicle systems, unless and until a new program is fed into the security system for pack replacement. A set of battery pack will match only the .corresponding, controller of the vehicle. Hence, theft of Battery pack can be avoided. In yet another embodiment, the printed circuit board (PCB) for BMS communication is integrated with the battery casing.

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 individual cells forming batteries (10) with atleast one positive terminal and atleast one negative terminal is enclosed in a battery case (1) and the battery case (1) is a slid-in battery case.
wherein the said battery (10) comprises of atleast one relief passage (91), a silicone valve (92) and a valve retainer (93) and the said silicone valve (92) forms a relief passage (101,102) for relieving gas formed in the said battery (10).

2. A power system for a hybrid vehicle 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 individual cells forming batteries (10) with atleast one positive terminal and atleast one negative terminal is enclosed in a battery case (1) and the battery case (1) is a slid-in battery case.

3. The power system for a hybrid vehicle as claimed in Claim (1) wherein atleast a portion of the said battery (10) is further equipped with an electronic security system (114), a handling provision (71, 72), fuse (73), and a sealing member (42. and 51) in between the battery end cover (41).

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

5. The power system for a hybrid vehicle as Claimed in Claim 1 or Claim 2 wherein the said battery (1) comprises of atleast one cell separator (3).

6. The power system for a hybrid vehicle as Claimed in Claim 1 or Claim 2 wherein the said electronic security system (114) is connected to a the said battery management system.

7. The power system for a hybrid vehicle as Claimed in Claim 1 or Claim 2 wherein the said battery (1) is equipped with RPBD tag.

8. The power system for a hybrid vehicle as Claimed in Claim 1 wherein the said cell (20) are placed inside a cell separator (4,5) in a circular manner.