Description:TECHNICAL FIELD
[001] The present subject matter relates to a power unit, more particularly, a configuration and structure of an interconnector of the power unit.
BACKGROUND
[002] In general, conventional vehicles are provided with a power unit to propel the vehicle. The power unit is an electric motor being powered by a battery, an internal combustion engine or a combination of both electric motor and the internal combustion engine.
[003] In conventional electric power unit, the battery is composed of a plurality of cells and the plurality of cells are electrically connected with a battery management system (BMS) for monitoring and calibrating functionality of each of the plurality of cells.
[004] The plurality of cells are connected with each other through a bus bar and the bus bar comprises a plurality of interconnectors to accommodate each of the plurality of cells. The plurality of cells are disposed on the interconnectors in a series and parallel configuration to form an electric circuit.
[005] The BMS is configured to detect and ascertain temperature of each cell of the plurality of cells to prevent over heating of the cells and thereby prevent thermal runaway of the battery.
[006] However, the BMS is capable of ascertaining the temperature of the cells once the temperature of the cell crosses over a threshold temperature. Further, there is a delay in ascertaining this temperature value of the cell and thereby there is a delay in preventing thermal runaway of the battery.
[007] In order to overcome this delay, the design of the interconnectors are changed to provide a fusing region. The fusing region short circuits and eliminates a faulty cell from the electric circuit as and when the temperature of the cell crosses over a threshold temperature. Thus, this layout prevents damage to the neighboring cells. However, the conventional design of the interconnectors increases the overall resistance of the battery during shorting of the fusing region of the interconnectors. This in turn increases the overall temperature of the battery.
[008] Furthermore, the existing design of the interconnectors uses nickel to provide electrical connection between the cells of the battery. However, the use of only nickel in interconnectors increases resistance of the fusing region of the interconnectors.
[009] Furthermore, the melting point of nickel is at a high temperature, for example around 1500 degree Celsius. This prolongs the time taken to melt the fusing region and thereby increases the time in isolating a faulty cell from the neighboring cells.
[010] Furthermore, as per AIS 156 - REESS shall have Active paralleling circuits for the parallel connection of cells and strings to eliminate circulating currents. These power semiconductor devices used for interconnecting strings will also act as protection/safety switches which will detect any faulty strings and isolate them. They will allow bidirectional flow of currents to charge and discharge the pack. The parallel cells and strings will get isolated if it is detected to be faulty. Therefore, active paralleling should be mandatory in the battery packs. Alternatively, fuses / bond wires can also be used to prevent circulating currents flowing through the cells connected in parallel. Such precautionary devices will help in isolation of faulty cells connected in parallel.
[011] Therefore, the conventional design of interconnectors includes elements which have high melting point, and such design requires complex tools to assemble the interconnectors which inadvertently increases the design complexity, assembling techniques and also increases the overall resistance of the battery.
[012] Hence it is an object of the present invention to provide an interconnector design which reduces overall resistance of the battery and also overcome other related problems known in the art.
[013] It is also an object of the present invention to prevent thermal runaway of the battery.
[014] It is also an object of the present invention to provide cell balancing of current flowing between the plurality of cells to prevent short circuiting of the plurality of cells.
[015] It is also an object of the present invention to provide ease of assembly of the interconnector without using complex design tools.
SUMMARY
[016] The present subject matter provides a power unit comprising a plurality of bus bars and a plurality of interconnectors for electrically connecting a plurality of cells with each other. The plurality of interconnectors being integrated with the plurality of bus bars using a first and a second joining techniques. The plurality of interconnectors being formed of a first element and the plurality of bus bars being composed of a second element for reducing overall resistance of the power unit.
[017] As per an aspect of the present invention, a power unit comprising a plurality of cells, a plurality of bus bars and a plurality of interconnectors. The plurality of bus bars being configured to electrically connect each of the plurality of cells with each other. The plurality of interconnectors are disposed along peripheral edges of each of the plurality of bus bars. The plurality of interconnectors and the plurality of bus bars are integrated using a first and a second joining techniques. The each of the plurality of interconnectors is composed of a first element and each of the plurality of bus bars is composed of a second element.
[018] As per an embodiment, the plurality of interconnectors is disposed in a plurality of openings of the each of the plurality of bus bars. The plurality of openings is configured to receive each of the plurality of interconnectors.
[019] As per another embodiment, the each of plurality of interconnectors is integrally attached to a portion of each of the plurality of bus bars through a conjoined link and the conjoined link is formed from the second element. The first element is nickel, and the second element is aluminum.
[020] As per another embodiment, the each of the plurality of interconnectors comprising a first region, a second region and a neck fusing region. The neck fusing portion is configured to isolate electrical connection of the one of the plurality of cells when the cell is a faulty cell due to short circuiting of the cell. The neck fusing region is a conjoined link for attaching each of the plurality of interconnectors with each of the plurality of bus bars.
[021] As per another embodiment, the first portion is configured to receive each of the plurality of cells through the first joining technique, and the first joining technique is a projection welding technique. The second portion is integrally fused with a portion of the each of the plurality of interconnectors through the second joining technique, and the second joining technique is laser welding and brazing technique.
[022] As per another embodiment, the each of plurality of interconnectors is configured to have a dimensions of a length in a range of 0-5mm, a width in the range of 0-0.5mm, and a thickness in the range of 0-0.2mm.
[023] As per another aspect of the present invention, a method for manufacturing each of the plurality of interconnectors in a power unit comprising the following steps. Firstly, casting a bus bar of plurality of bus bars from a first element and casting of each of the plurality of interconnectors from a second element. Secondly, integrating a cell from the plurality of cells on a first region of each of the plurality of interconnectors using a first joining technique, and then integrating a second region of each of the plurality of interconnectors on a portion of the bus bar of the plurality of bus bars using a second joining technique. Finally, integrating a neck fusing region of each of plurality of interconnectors using a second joining technique and the neck fusing region is formed of the second element.
[024] As per another embodiment, the first element is aluminum, and the second element is nickel. The first joining technique is projection welding technique, and the second joining technique is laser welding and brazing technique.
[025] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

BRIEF DESCRIPT ION OF THE DRAWINGS
[026] The present invention is described with reference to figures. This invention is implementable in two-wheeled, three wheeled, and four wheeled vehicles. The same numbers are used throughout the drawings to reference like features and components. Further, the inventive features of the invention are outlined in the appended claims.
[027] Figure 1 illustrates a left perspective view of a power unit, in accordance with an embodiment of the present subject matter.
[028] Figure 2 illustrates a top view of a plurality of bus bars of the power unit, in accordance with an embodiment of the present subject matter.
[029] Figure 3a illustrates a side view of the plurality of bus bars of the power unit, in accordance with an embodiment of the present subject matter.
[030] Figure 3b illustrates a perspective view of one of a plurality of bus bars of the power unit, in accordance with an embodiment of the present subject matter.
[031] Figure 3c illustrates a top view of the plurality of bus bars of the power unit, in accordance with an embodiment of the present subject matter.
[032] Figure 4 illustrates a top view of an interconnector of the plurality of interconnectors being disposed in each of the plurality of bus bars, in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION OF THE DRAWINGS

[033] Exemplary embodiments are described with reference to the accompanying drawings. Wherever convenient, the same reference numbers are used throughout the drawings to refer to the same or like parts. While examples and features of disclosed principles are described herein, modifications, adaptations, and other implementations are possible without departing from the scope of the disclosed embodiments. It is intended that the following detailed description be considered as exemplary only, with the true scope being indicated by the following claims.
[034] The present subject matter is further described with reference to accompanying figures. It should be noted that the description and figures merely illustrate the principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.
[035] The foregoing disclosure is not intended to limit the present disclosure to the precise forms or particular fields of use disclosed. As such, it is contemplated that various alternate embodiments and/or modifications to the present disclosure, whether explicitly described or implied herein, are possible in light of the disclosure. Having thus described embodiments of the present disclosure, a person of ordinary skill in the art will recognize that changes may be made in form and detail without departing from the scope of the present disclosure. Thus, the present disclosure is limited only by the claims.
[036] Additionally, all numerical terms, such as, but not limited to, “first”, “second”, “third”, “primary”, “secondary”, “main” or any other ordinary and/or numerical terms, should also be taken only as identifiers, to assist the reader's understanding of the various elements, embodiments, variations and/or modifications of the present disclosure, and may not create any limitations, particularly as to the order, or preference, of any element, embodiment, variation and/or modification relative to, or over, another element, embodiment, variation and/or modification.
[037] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[038] Figure 1 illustrates a left perspective view of a power unit (100), in accordance with an embodiment of the present subject matter. A power unit (100) comprising a top cover (102), a bottom cover (106) and a plurality of side covers (104). In one embodiment, the plurality of side covers (106) is configured to have a plurality of vents for air circulation and ventilation of a plurality of cells (not shown) being disposed inside the power unit (100). In one embodiment, the plurality of cells being cylindrical cell or a prismatic cell. The plurality of cells are connected electrically with each other through an electrical circuit. The plurality of cells are further connected with a battery management system (BMS) (not shown). The BMS is configured to monitor and calibrate cell health of the plurality of cells and thereby prevent thermal runaway of the power unit (100).
[039] Figure 2 illustrates a top view of a plurality of bus bars (202) of the power unit (100), in accordance with an embodiment of the present subject matter. The plurality of cells (not shown) of the power unit (100) is electrically connected through a plurality of bus bars (202). The plurality of cells (not shown) are disposed in a series and parallel configuration on the plurality of bus bars (202). The plurality of bus bars (202) are disposed on a top surface and a bottom surface of the plurality of cells (not shown). Further each of the plurality of bus bars (202) is disposed adjacent to each other, and each of the plurality of bus bars (202) being configured to have one or more peripheral edges (204). The plurality of bus bars (202) is configured to electrically connect the plurality of cells (not shown) to the BMS (not shown). The BMS is configured to monitor the temperature of the plurality of cells and in reduces the risk of thermal runaway of the power unit (100).
[040] Figure 3a illustrates a side view of the plurality of bus bars of the power unit, in accordance with an embodiment of the present subject matter. Figure 3b illustrates a perspective view of one of a plurality of bus bars of the power unit, in accordance with an embodiment of the present subject matter. Figure 3c illustrates a top view of the plurality of bus bars (202) of the power unit (100), in accordance with an embodiment of the present subject matter. For brevity, figures 3a, 3b and 3c will be discussed together. The each of the plurality of bus bars (202) is configured to include a plurality of interconnectors (302). The each of the plurality of bus bars (202) is configured have an extended end (202a) for connecting the plurality of bus bars (202) with the BMS (not shown). The plurality of interconnectors (302) are disposed along the one or more peripheral edges (204) of the each of the plurality of bus bars (202). The plurality of interconnectors (302) are disposed in a zig zag fashion along the one or more peripheral edges (204) of the each of the plurality of bus bars (202).
[041] The each of the plurality of interconnectors (302) are disposed in a plurality of openings (304) of the each of the plurality of bus bars (202). The plurality of openings (304) is configured to accommodate the each of the plurality of interconnectors (302) through a first joining technique and a second joining technique. In one embodiment, the first joining technique is a projection welding technique, and the second joining technique is a laser welding and brazing technique. The each of the plurality of bus bars (202) comprising a curved surface (301a) and a flat surface (301b). The curved surface (301a) and the flat surface (301b) are configured to alternate along the one or more peripheral edges (304) of the each of the plurality of bus bars (202).
[042] Figure 4 illustrates a top view of an interconnector of the plurality of interconnectors (302) being disposed in each of the plurality of bus bars (202), in accordance with an embodiment of the present subject matter. The each of the plurality of interconnectors (302) comprising a first region (400), a second region (402) and a neck fusing region (404). The first region (400) is configured to electrically connect the plurality of cells (not shown) with the each of the plurality of bus bars (202). The first region (400) is divided into two portions and the two portions is divided by a linear gap (408). The second region (402) is integrated with the first region (400). The second region (402) is integrated with the each of the plurality of bus bars (202) through the second joining technique. The first region (400) is fused with the second region (402) and to each of the plurality of bus bars (202) using the first joining technique. In one embodiment, the first joining technique is the projection welding technique, and the second joining technique is the laser welding and brazing technique. In one embodiment, the first and second joining techniques being metallurgically fusing techniques to form one or more metal alloys.
[043] The neck fusing region (404) is a conjoined link acting as a shorting element for isolation of faulty cells from neighboring cells. The neck fusing region (404) is also configured for attaching the each of the plurality of interconnectors (302) with each of the plurality of bus bars (202). When a current passing through the plurality of cells (not show) is higher than a specified predefined current, and the current is passed through the neck fusing region (404), having the fusing cross section area, the neck fusing region (404) melts away at that moment thus saving the pack to go into thermal runaway. The neck fusing region (404) being composed of the second element, which is aluminum, in one embodiment.
[044] The neck fusing region (404) is composed of a first element and the neck fusing region (404) is fused using the second joining technique with the each of the plurality of bus bars (202). The first region (400) is composed of a first element and the first element is nickel in one embodiment. The second region (402) is composed of the first element nickel, and the nickel is fused on the first element which is aluminum, on the plurality of bus bars (202). The composition of the each of the plurality of interconnectors (302) with the first element and the second element reduces the overall resistance of the power unit (100) and aids in reducing the risk of thermal runaway. In one embodiment, the each of plurality of interconnectors (302) being configured to have a dimensions of a length in a range of 0-5mm, a width in said range of 0-0.5mm, and a thickness in said range of 0-0.2mm.
[045] Various embodiments of the invention provides a power unit comprising a plurality of bus bars and a plurality of interconnectors for electrically connecting a plurality of cells with each other. The plurality of interconnectors being integrated with the plurality of bus bars using a first and a second joining techniques. The plurality of interconnectors being formed of a first element and the plurality of bus bars being composed of a second element for reducing overall resistance of the power unit.
[046] The present invention is a power unit comprising a plurality of cells, a plurality of bus bars and a plurality of interconnectors. The plurality of bus bars being configured to electrically connect each of the plurality of cells. The plurality of interconnectors are disposed along one or more peripheral edges of each of the plurality of bus bars. The plurality of interconnectors and the plurality of bus bars are integrated using a first and a second joining techniques. The each of the plurality of interconnectors is composed of a first element and each of the plurality of bus bars is composed of a second element.
[047] The present claimed invention solves the technical problem of increased resistance of the power unit due to the plurality of interconnectors and the plurality of bus bars being made of a single element such as nickel, which is also increases the overall cost of the power unit as nickel is an expensive metal.
[048] Specifically, the claimed power unit having the design and configuration of the plurality of interconnectors being fused and integrated with the plurality of interconnectors of different metallic configurations, reduces the overall resistance of the power unit and increases life of the power unit by reducing the risk of thermal runaway of the power unit.
[049] Additionally, the configuration of combination elements being used to make the plurality of interconnectors, reduces the overall melting point of the power unit and in turn the neck fusing region of the plurality of interconnectors, melts away faster to isolate a faulty cell and thereby prolongs the life of the power unit.
[050] The present invention also provides technical advantages of prevention of thermal runaway of the power unit and reduction in overall weight and cost of the power unit.
[051] In light of the above-mentioned advantages and the technical advancements provided by the disclosed power unit, the claimed steps as discussed above are not routine, conventional, or well understood in the art, as the claimed steps enable the following solutions to the existing problems in conventional technologies. Further, the claimed steps clearly bring an improvement in the design and configuration of a plurality of interconnectors of the power unit which reduces the overall resistance of the power unit and also isolates a faulty cell from the plurality of cells during short circuiting of the plurality of cells as the claimed steps provide a technical solution to a technical problem.
[052] While the present invention has been shown and described with reference to the foregoing preferred embodiments, it will be apparent to those skilled in the art that changes in form, connection, and detail may be made therein without departing from the spirit and scope of the invention.

Reference Numerals:



100 power unit
102 top cover
104 plurality of side covers
106 bottom cover
202 plurality of bus bars
204 one or more peripheral edges
202a extended end
301a curved surface
301b flat surface
302 plurality of interconnectors
304 plurality of openings
400 first region
402 second region
404 neck fusing region
408 linear gap

, Claims:I/We claim:
1. A power unit (100) comprising:
a plurality of cells;
a plurality of bus bars (202), wherein said plurality of bus bars (202) being configured to electrically connect each of said plurality of cells with each other;
a plurality of interconnectors (302), wherein said plurality of interconnectors (302) being disposed along one or more peripheral edges (204) of each of said plurality of bus bars (202);
wherein said plurality of interconnectors (302) and said plurality of bus bars (202) being integrated using a first and a second joining techniques, and
wherein each of said plurality of interconnectors (302) being composed of a first element and said each of said plurality of bus bars (202) being composed of a second element.
2. The power unit (100) as claimed in claim 1, wherein said plurality of interconnectors (302) being disposed in a plurality of openings (304) of each of said plurality of bus bars (202), wherein said plurality of openings (304) being configured to receive each of said plurality of interconnectors (302).
3. The power unit (100) as claimed in claim 2, wherein said each of plurality of interconnectors (302) being integrally attached to a portion of each of said plurality of bus bars (202) through a conjoined link, wherein said conjoined link being formed of said second element.
4. The power unit (100) as claimed in claim 1, wherein said first element being nickel and said second element being aluminum.
5. The power unit (100) as claimed in claim 1, wherein each of said plurality of interconnectors (302) comprising a first region (400), a second region (402) and a neck fusing region (404).
6. The power unit (100) as claimed in claim 5, wherein said neck fusing region (404) being configured to isolate electrical connection of one of said plurality of cells when said cell being short circuited, wherein said neck fusing region (404) being said conjoined link attaching said each of said plurality of interconnectors (302) and said each of said plurality of bus bars (202).
7. The power unit (100) as claimed in claim 5, wherein said first portion (400) being configured to receive each of said plurality of cells through said first joining technique, wherein said first joining technique being a projection welding technique.
8. The power unit (100) as claimed in claim 5, wherein said second portion (402) being integrally fused with a portion of said each of said plurality of interconnectors (302) through said second joining technique, wherein said second joining technique being laser welding and brazing technique.
9. The power unit (100) as claimed in claim 1, wherein said each of plurality of interconnectors (302) being configured to have a dimensions of a length in a range of 0-5mm, a width in said range of 0-0.5mm, and a thickness in said range of 0-0.2mm.
10. A method for manufacturing each of a plurality of interconnectors (302) in a power unit (100), said method comprising steps of:
casting, a bus bar of plurality of bus bars (202), from a first element;
casting, said each of plurality of interconnectors (302), from a second element;
integrating, a cell from a plurality of cells on a first region (400) of said each of said plurality of interconnectors (302), using a first joining technique;
integrating, a second region (402) of said each of said plurality of interconnectors (302) on a portion of said bus bar of said plurality of bus bars (302), using a second joining technique;
integrating, a neck fusing region (404) of said each of plurality of interconnectors (302) using a second joining technique, wherein said neck fusing region (404) being formed of said second element.
11. The method as claimed in claim 10, wherein said first element being aluminum and said second element being nickel.
12. The method as claimed in claim 10, wherein said first joining technique being a projection welding technique and said second joining technique being laser welding and brazing technique.