TECHNICAL FIELD

[0001] The present subject matter relates to battery modules. More particularly, impact resistant battery modules are disclosed.

BACKGROUND

[0002] Existing research in battery technology is directed to rechargeable batteries, such as sealed, starved electrolyte, lead/acid batteries, are commonly used as power sources in different applications, such as, vehicles and the like. However, the lead- acid batteries are heavy, bulky, and have short cycle life, short calendar life, and low turn around efficiency, resulting in limitations in applications.

[0003] Thus, in order to overcome problems associated with conventional energy storage devices including the lead-acid batteries, a lithium ion battery provides an ideal system for high energy-density applications, improved rate capability, and safety. Further, the rechargeable energy storage devices - lithium-ion batteries exhibit one or more beneficial characteristics which makes it useable on powered devices. First, for safety reasons, the lithium ion battery is constructed of all solid components while still being flexible and compact. Secondly, the energy storage device including the lithium ion battery exhibits similar conductivity characteristics to primary batteries with liquid electrolytes, i.e., deliver high power and energy density with low rates of self-discharge. Thirdly, the energy storage device as the lithium ion battery is readily manufacturable in a manner that it is both reliable and cost-efficient. Finally, the energy storage device including the lithium ion battery is able to maintain a necessary minimum level of conductivity at sub-ambient temperatures. By virtue of these advantages, the energy storage devices find applications in rugged environments with increased ambient temperatures. However, the energy storage devices are susceptible to vibrations during their lifetime, which may lead to functional failure and fatigue damage to the energy storage devices. The construction of the energy storage devices is critical to the longevity, safety, serviceability, and maintainability of the energy storage devices. BRIEF DESCRIPTION OF DRAWINGS

[0004] The detailed description is described with reference to the accompanying figures. The same numbers are used throughout the drawings to reference like features and components.

[0005] Fig. 1 exemplarily illustrates an exploded perspective view of a battery module;

[0006] Fig. 2 exemplarily illustrates a perspective view of a battery pack of the battery module exemplarily illustrated in Fig. 1;

[0007] Figs. 3A-3B exemplarily illustrate a front perspective view and a front view respectively of a damper in the battery module, as per an embodiment of the present invention;

[0008] Fig. 4 exemplarily illustrates an exploded perspective view of the damper, as per an embodiment of the present invention;

[0009] Fig. 5 exemplarily illustrates a bottom perspective view of a cushioning member of the damper;

[00010] Figs. 6A-6B exemplarily illustrate the perspective view of a solid seat member of the damper; and

[00011] Fig. 7 exemplarily illustrates a front perspective view of an embodiment of the damper of the battery module.

DETAILED DESCRIPTION OF THE INVENTION

[00012] An energy storage device comprises one or more energy storage cells, such as, lithium ion battery cells enclosed within a casing. The energy storage device may be used in driving electric vehicles or hybrid electric vehicles. On deployment of the electric or hybrid electric vehicles in rugged environment, the vehicle frame is subjected to vibrations. Such vibrations are transmitted to the energy storage device in the vehicle. The casing of the energy storage device experiencing the vibrations, transmits the vibrations to the energy storage cells affecting the functionality of the energy storage device in long run.

[00013] Also, marginal deviation in design of the casing or the design of the cell holders can result in loose packaging of the energy storage cells within the casing. Such a packaging can compromise cycle life of the energy storage device. The vibrations may also set exothermic reactions within the energy storage cells resulting in release of smoke or toxic gases and high-pressure events leading to a catastrophic failure of the energy storage device. A reliable packaging of the energy storage device is needed for mechanical stability, durability, thermal stability, vibration isolation, and impact resistance of the energy storage device.

[00014] Existing packaging of the energy storage cells within a casing employs a packaging material that which can withstand raised temperatures and pressures. However, the packaging material needs to be uniformly distributed along the length of the casing using a fastening means. However, the packaging material increases the weight, the manufacturing cost, and the assembling cost of the energy storage device. Also, while loading or unloading the assembly of the energy storage cells into the casing, the packaging material may hinder the ease in pushing in or pulling out of the energy storage cells from the casing. To address this problem, the packaging material has to be made firm and rigid to not deform, while loading and unloading of the assembly of the energy storage cells.

[00015] Further, based on the application of the energy storage device, the capacity of the energy storage device is varied. Based on the capacity of the energy storage device, the number of energy storage cells, the mass of the energy storage cells, and the capacity of the energy storage cells, etc., are varied. If energy storage cells with reduced size or mass are to be enclosed within an existing casing, a gap may be formed between the casing and the energy storage cells. Such gaps will result in not a very tight packaging of the energy storage cells in the energy storage device. This loose gap in the configuration of packaging between the energy storage cells and the casing will not provide adequate protection to the energy storage cells from vibrations, pressure, temperature, and abuse experienced by the casing. If a packaging material that is rigid and firm is used, it may not allow for the flexibility of using an existing casing for different assemblies of the energy storage cells. This may lead to manufacture of different casings for different assemblies of the energy storage cells increasing material cost and manufacture cost of entities.

[00016] There exists a need for an improved design of an energy storage device with a packaging between the assembly of energy storage cells and a casing to ensure ease and safety during assembly, use, maintenance, and servicing of the energy storage device overcoming all problems disclosed above as well as other problems of known art.

[00017] The present subject matter discloses an energy storage device, that is, a battery module comprising an improved and simplified design of a packaging for impact resistance, shock isolation, and vibration dampening of a battery module. Such a battery module may be employed in powered devices, such as, vehicles, for example, electric vehicle, hybrid electric vehicles, IC engine vehicles, etc.

[00018] In an embodiment of the present invention, a battery module for a powered device is disclosed. The battery module comprises one or more cell holders, multiple cells positioned in the cell holders, and a casing enclosing the cells in the cell holders. Further, one or more dampers are positioned at predetermined locations of the cell holders for rigidity of the battery module. Each of the dampers comprise a hollow cushioning member, a solid seat member, and a stem portion extending from the seat member. The hollow cushioning member is accommodated in a space between the cell holders and the casing. The hollow cushioning member comprises one or more extenders extending from underneath a first surface. The solid seat member comprises depression with one or more ribs engaging with the extenders of the cushioning member. The stem portion extends from underneath the depression of the seat member and locks into an aperture at the predetermined locations of the cell holders. The position and the embodiments of the structure of the dampers are disclosed in the detailed description of Figs. 2-7.

[00019] Fig. 1 exemplarily illustrates an exploded perspective view of a battery module 100. The battery module 100 comprises a first end cover 101, a second end cover 104, a casing 103, and a battery pack 102. The dovetail pattern of the external casing 103 facilitates easy mounting and unmounting of the battery module 100 in a designated space in a powered device. The external casing 103 encloses the battery pack 102 from top and bottom. The second end cover 104 and the front end cover 101 enclose the battery pack 102 from rear and front respectively. The battery pack 104 comprises a plurality of cells arranged in a particular sequence between one or more cell holders 105. The cells are electrically connected in series and/or parallel configuration to form an array of cells. Such arrays of cells are electrically connected to a battery management system (BMS) 106 within the battery module 100. The BMS 106 is a printed circuit board with one or more integrated circuits integrally built on it as exemplarily illustrated in Fig. 2. The external casing 103 has mounting provisions for the second end cover

104 and the first end cover 101. The second end cover 104 and the first end cover 101 are fastened to the external casing 103 using a plurality of attachment means. The external casing 101 with a dovetail pattern that allows easy insertion and removal of the battery module 100 into a battery mounting bracket. The dovetail pattern also is formed on the interior side of the casing 103. The dovetail pattern on the interior side allows easy sliding of the battery pack 104 into the casing 103.

[00020] As per a preferred embodiment, the attachment means can be fasteners. The battery pack 102 has mounting provisions for the BMS board 106. The BMS board 106 is screwably attached to the cell holders 105 of the battery pack 102. The BMS board 106 is located between the battery pack 102 and the first end cover 101. One or more dampers, such as, 107a are positioned at predetermined locations of the cell holders 105 for rigidity of the battery module 100.

[00021] Fig. 2 exemplarily illustrates a partially exploded perspective view of the battery pack 102 of the battery module 100 exemplarily illustrated in Fig. 1. As exemplarily illustrated, the battery pack 102 comprises the cell holders 105 and the BMS board 106 removably attached to the cell holders 105. The cell holders

105 comprise a first cell holder 105a and a second cell holder 105b. The cell holders 105 comprise placeholders for holding a cell, such as, 201 in each placeholder. Each of the cell holders 105 comprises a planar surface, such as, 105c with the placeholders and raised edges, such as, 105d at the sides of the planar surface 105c. One of the cell holders 105b is positioned at the bottom of the cells 201 and another cell holder 105a is positioned on top of the cells 201. The cell holders 105 are fixed together using a plurality of fasteners to tightly hold the cells 201 in the placeholders. The raised edges, such as, 105d of the cell holders 105a and 105b come in contact with each other, when the cell holders 105a and 105b are fixed together. To fasten the cell holders 105a and 105b together, recesses such as, 203 to position the fasteners are provided in the cell holders 105a and 105b. The battery pack 102 further comprises a protective sheet 202 positioned above an interconnect sheet of the battery pack 102.

[00022] As an embodiment, the cell holders 105a and 105b may be rectangular in shape and holding cylindrical cells in the placeholders. As exemplarily illustrated, the dampers 107a, 107b, ... , 107f, 107g are positioned at predetermined locations, such as, 204a of the cell holders 105. The dampers 107a, 107b, ... , 107g may be positioned on the sides of the cell holders 105a and 105b that come in contact with the casing 103 of the battery module 100. That is, in total for the rectangular cell holders 105a and 105b, there are 8 dampers, 4 at the shorter edges of each of the cell holders 105a and 105b. The dampers 107c, 107d, 107e, and 107g are positioned on the raised edges of the top cell holder 105a. The dampers 107a, 107b, 107g, and another damper (not visible but referred to as 107h) are positioned on the raised edges of the bottom cell holder 105b. In an embodiment, the dampers 107a, 107b, ... , 107h may be positioned at shorter raised edges 105f of the cell holders 105a and 105b that come in contact with sides of the casing 103. On the longer raised edges 105e of the cell holders 105a and 105b, the end cover, for example, the second end cover 104, and the BMS board 106 are mounted. The predetermined location, such as, 204a may be at center of the edges 105f or proximal to vertices 205 of the cell holders 105a and 105b. At the predetermined locations, such as, 204a depressions or recesses are formed on the cell holders 105a and 105b or a part of the cell holder 105a or 105b is excavated. The damper, such as, 107c sits in the depressions and may bulge away from the cell holders 105a and 105b. When the battery pack 102 is positioned in the casing 103, the bulge in the damper, such as, 107c may occupy the space between the battery pack 102 and the casing 103. At the depressions, an aperture, such as, 204b is provided to insert the damper, such as, 107d into the cell holders 105a and 105b. As exemplarily illustrated, the dampers 107a, 107b, ... , 107h are located on top and bottom short edges, such as, 105f of the battery pack 102.

[00023] Figs. 3A-3B exemplarily illustrate a front perspective view and a front view respectively of the damper, such as, 107a in the battery module 100, as per an embodiment of the present invention. As exemplarily illustrated, the damper 107a comprises a hollow cushioning member 301, a solid seat member 302, and a stem portion 303. The hollow cushioning member 301 is accommodated in the space between the cell holders 105a and 105b and the casing 103. The hollow cushioning member 301 forms the bulge portion of the damper 107a. The hollow cushioning member 301 is attached with the solid seat member 302. The solid seat member 302 rests at the predetermined locations, such as, 204a of the cell holders 105a and 105b. A bottom profde of the solid seat member 302 comprises a groove 302a that corresponds to the short edges 105f of the cell holders 105a and 105b. The groove 302a facilitates resting of the solid seat member 302 in the depressions in the cell holders 105a and 105b. The stem portion 303 of the damper 107a extends from underneath the depressions in the seat member 302, locking into the aperture 204b at the predetermined location 204a of the cell holders 105a and 105b.

[00024] The stem portion 303 is inserted into the aperture 204b at the predetermined location 204a of the cell holders 105a and 105b. As exemplarily illustrated in Fig. 3B, the stem portion 303 comprises at least two parallel half locking units, such as, 303a with locking ridges 303b at a distal end. As exemplarily illustrated, two parallel locking units, such as, 303a constitute the stem portion 303. In an embodiment, three or more parallel locking units, such as, 303a constitute the stem portion 303 of the damper 107a. Each of the locking units 303a comprises a locking ridge 303b at a distal end. The locking units 303a are pressed towards each other and the stem portion 303 is inserted into the aperture 204b of the predetermined location 204a of the cell holders 105a and 105b. Once the stem portion 303 is inserted into the aperture 204b, the locking units 303a move to their original position. In the inserted position, the locking ridge 303b of the stem portion 303 arrests uprooting of the damper 107a at the predetermined location 204a of the cell holders 105a and 105b.

[00025] Fig. 4 exemplarily illustrates an exploded perspective view of the damper 107a, as per an embodiment of the present invention. As exemplarily illustrated, the damper 107a comprises the hollow cushioning member 301, the solid seat member 302, and the stem portion 303. The cushioning member 301 comprises one or more extenders 301b extending from underneath the first surface 301a. That is, the first surface 301a of the hollow cushioning member 301 forms the bulge portion and the extenders, such as, 301b extend from beneath the bulge portion. The first surface 301a of the hollow cushioning member 301 is a convex surface. The hollow cushioning member 301 is formed of a resilient material, such as, rubber. In an embodiment, beneath the first surface 301a, four extenders, such as, 301b are provided. The extenders 301b are also made of the resilient material. The extenders 301b are flat and firm to engage with ribs 302d of the solid seat member 302. The number of extenders 301b is designed based on the number of the ribs 302d of the seat member 302.

[00026] A front profile of the cushioning member 301 is the convex first surface 301a with sides 301c extending longer than the extenders 301b. A top profile of the solid seat member 302 as exemplarily illustrated, is a four walled structure. Two raised opposite walls 302b in the top profile of the solid seat member 302 are enclosed by the sides 301c of the cushioning member 301. Thus, on engaging of the cushioning member 301 with the seat member 302, the two raised opposite walls 302b of the seat member 302 are enclosed within the cushioning member 301. The end 301e of the convex first surface 301a is in abutment contact with a lower wall 302c of the solid seat member 302, when the seat member 302 is engaged with the cushioning member 301.

[00027] The solid seat member 302, when viewed from top, comprises a centrally configured depression with ribs 302d bound by the walls 302b and 302c of the solid seat member 302. The ribs 302d are designed in a pattern corresponding to the design of the extenders 301b. The ribs 302d are raised edges of the material of the seat member 302 that engages in the spaces between the extenders 301b of the cushioning member 301. The ribs 302d diagonally extend as exemplarily illustrated in Fig. 4 from an epicenter 302e in the depression. In an embodiment, the ribs 302d extend sideways from the epicenter 302e in the depression. The seat member 302 is made of a polymeric or resin material that is firm and sturdy to hold the cushioning member 301 at the predetermined locations of the cell holders 105a and 105b.

[00028] The bottom profile of the solid seat member 302 comprises the groove 302a that matches with the profile of the depression in the cell holders 105a and 105b. The solid seat member 302 rests at the predetermined locations 204a of the cell holders 105a and 105b. The cushioning member 301 and the seat member 302 engaged with each other are locked in the aperture 204b at the predetermined location 204a of the cell holders 105a and 105b using the stem portion 303 preferably in a snug fit or interference fit manner.

[00029] Fig. 5 exemplarily illustrates a bottom perspective view of the cushioning member 301 of the damper 107a. As exemplarily illustrated, the extenders 301b extend from underneath the first surface 301a. Further, the extenders 301b appear to originate from an empty epicenter 301d underneath the first surface 301a. The extenders 301b are designed corresponding to the design of the ribs 302d of the seat member 302.

[00030] Figs. 6A-6B exemplarily illustrate the perspective view of the solid seat member 302 of the damper 107a. As exemplarily illustrated in Fig. 6A, four ribs, such as, 302d in the depression of the solid seat member 302 may originate from the epicenter 302e. Fig. 6B exemplarily illustrates only two ribs , such as, 302d originating from the epicenter 302e and extends sideways from the epicenter 302e to the walls 302b of the seat member 302.

[00031] Fig. 7 exemplarily illustrates a front perspective view of an embodiment of the damper 107a of the battery module 100. The hollow cushioning member 301 of the embodiment of the damper 107a illustrated in Fig. 7 comprises a depression 701 on the first surface 301a for inserting a fastener to fasten the cushioning member 301 and the seat member 302 to the cell holders 105a and 105b. The aperture 702 in the depression 701 for the fastener is in-line with the depression on the cell holders 105a and 105b of the battery module 100. In such an embodiment of the damper 107a, the stem portion, such as, 303 is absent and the damper 107a is held in position at the predetermined location 204a of the cell holders 105a and 105b using the fasteners inserted through the cushioning member 301. In an embodiment, the aperture 702 in the depression 701 in the cushioning member 301 may include threads for screwing a fastener into the aperture 702.

[00032] The different embodiments of the damper disclosed herein are positioned at the edges of the cell holders and allow the easy sliding in and sliding out of the battery pack from the casing. The damper fills the gap between the casing and the battery pack. The cushioning member of the damper provides impact/shock resistance to the battery pack. The resilient material of the cushioning member of the damper functions as a vibration absorber that is experienced by the casing of the battery module. During the assembly of the battery module, the positioning of the dampers is simple and requires only insertion of the stem portion of the damper at the predetermined locations of the cell holders. The number of parts to position the dampers are reduced also, thereby reducing the cost of manufacture, assembly, maintenance, and servicing. If incase, the BMS board of the battery module needs to be serviced, the dampers do need to be removed from their location as the mounting location of the BMS board to the cell holders and the dampers is clearly distinguished. In cases where the same casing used for battery packs of different capacity, the dampers will fill the gap between the battery pack and the casing. In an embodiment, only the dampers are to be altered if the gap between the battery pack and the casing is varied. By retaining the same damper or altering the damper, the cost of redesigning the casing and the cell holders is completely avoided, thereby saving manufacturing cost of the new battery module and giving tremendous flexibility for a manufacturer to have variety of battery packs with various capacities to cater to different product variants, different markets etc. without compromising on the complexity of manufacturing, increasing variety as well as complexity of assembly. Thus, the dampers as per present invention provide mechanical stability, thermal stability, durability, vibration isolation, and impact resistance to the battery module while enabling breaking of trade-off on variety creation versus ease of manufacturing and assembly leading to a reliable energy module for a powered device along with a robust casing capable of withstanding various loads arising out of its usage as well as its process of assembly cum manufacturing.

[00033] Improvements and modifications may be incorporated herein without deviating from the scope of the invention.