The present invention relates to a battery cell holder and to a battery system having a plurality of battery cells.
The present invention proceeds from cylindrical battery cells, in particular lithium ion cells, that preferably have numerous utilization capabilities as rechargeable electrochemical energy reservoirs. Usually, a plurality of battery cells is provided as an electrical grouping. Typical cylindrical lithium ion battery cells of this kind are standardized in terms of their dimensions, for example in the “18650” format (18 mm diameter, 65 mm height). The battery cells have relatively large dimensional tolerances, however, which can result in problems when disposing a plurality of battery cells in a housing. Lithium ion battery cells of this kind also experience changes in volume during a charging cycle and discharging cycle, which must be compensated for. In addition, such battery cells and battery systems are often subject to additional stresses due to vibration, oscillations, or entry and exit of gaseous or liquid media, which can result in damage to such battery systems. An increased need therefore exists for improved battery cell holders and battery systems.
A battery cell holder according to an example embodiment of the present invention may have the advantage that a tolerance compensation in several directions is possible even in a context of very large manufacturing-related tolerances, and the battery cell can thus be retained securely in the battery cell holder. This makes possible a considerable simplification in the processing of battery cells of different batches and/or from different manufacturers, which (as experience indicates) always have different tolerances. In addition, the battery cells held with the battery cell holder according to the present invention can be protected in controlled fashion with respect to vibrations, oscillations, impacts, and the like. In particular, reliable vibration decoupling can be implemented. Additional thermal, contact-based coupling of the individual battery cells can furthermore be enabled, resulting in considerably better heat dissipation from individual battery cells over long periods of time. This is achieved according to an example embodiment of the present invention by the fact that the battery cell holder has a housing made of an inelastic material, in particular a hard plastic. The housing is configured to receive and retain a plurality of individual battery cells. The battery cell holder furthermore encompasses an elastic intermediate unit. Also provided is a preload device that is configured to exert a preload force on the elastic intermediate unit in such a way that the elastic intermediate unit becomes deformed and the battery cell becomes clamped by way of the deformed elastic intermediate unit. Before exertion of the preload force there thus exists, between the elastic intermediate unit and the inserted individual battery cells, a respective interstice that then disappears after application of the preload force of the preload device. The individual battery cells are thus, as a result of the elastic intermediate unit, in contact therewith after application of the preload force, and are securely retained.
Preferred refinements of the present invention are disclosed herein.
The elastic intermediate unit preferably encompasses an elastic, one-piece insert, similar to a perforated panel, having a plurality of passthrough openings. Such inserts can be manufactured easily and inexpensively in large quantities from elastic material.
Also preferably, the battery cell holder in accordance with an example embodiment of the present invention encompasses a multi-part housing, in particular a two-part housing; the preload device being configured in such a way as to exert a preload force on the housing so that the elastic intermediate unit becomes elastically deformed in order to clamp the batteries. The preload force can thus be transferred from outside the housing onto the housing, and via the housing onto the elastic intermediate unit. The preload device thus does not need to be disposed in the interior of the housing, so that the battery cells can be disposed very compactly.
Also preferably, the preload device is adjustable. It is thereby possible to vary a preload force so that, in particular, different dimensional discrepancies of the battery cells can be reacted to. The adjustable preload device can be implemented, for example, by way of a screw connection or an adjustable spring element or the like.
Alternatively, the preload device is configured in such a way that the preload device applies only a predetermined preload force. This approach is particularly inexpensive but can cause the respective preload forces on the battery cells to be different in a context of differing tolerances for different individual battery cells. This is acceptable, however, and does not result in disadvantages in terms of the use of the battery cells. A preload device of this kind can be implemented, for example, by way of a welded connection between, for instance, the cover and a base of the housing, or by way of clip elements or the like that hold the cover on the base.
Also preferably, according to an alternative embodiment the battery cell holder has a preload device having a plurality of pin elements. The elastic intermediate unit has a plurality of auxiliary holes at transition regions between the passthrough openings in order to receive the battery cells. Each pin element is respectively disposed in an auxiliary hole. The pin elements have a diameter that at least in part is greater than a diameter of the auxiliary holes. The result is to expand the auxiliary holes so that the elastic deformation of the elastic intermediate unit occurs. The battery cells are thereby clamped. The pin elements are equipped, for example, with a conical end and with a cylindrical part having a larger diameter than the diameter of the auxiliary holes, or alternatively are embodied entirely with a conical or otherwise tapering main body. The pin elements preferably have a head, thereby simplifying insertion into and removal from the auxiliary holes.
The battery cell holder is preferably constructed in such a way that the multi-part housing comes into contact with the pin elements upon assembly, and the housing is configured to push the pin elements into the auxiliary holes.
Projecting regions can preferably be provided on the housing in the region of the pin elements.
Also preferably, the elastic intermediate unit encompasses at least a first elastic element and a second elastic element. The two elastic elements are disposed in the battery cell holder with a spacing from one another in an axial direction of the passthrough openings. As a result, the inserted batteries are securely retained by the elastic intermediate unit at two points, namely by the first and the second elastic element.
For cost reduction, the first and the second elastic element are preferably of identical construction.
Also preferably, the battery cell holder encompasses a bracing element made of an inelastic material, which is disposed adjacently to the elastic intermediate unit. The bracing element is preferably disposed between the first and the second elastic element in an axial direction of the passthrough openings. The bracing element serves as a support when the preload device exerts a preload force on the multi-part housing and the first and the second elastic element become elastically deformed.
The bracing element preferably encompasses a plurality of individual sleeves that are oriented in the first and the second elastic element to correspond to the passthrough openings. Alternatively, the bracing element encompasses a one-piece element, similar to a perforated panel, having a plurality of passthrough openings that are oriented in accordance with the passthrough elements in the first and the second elastic element.
The housing preferably has a base and a cover. Openings for electrical contacting of the individual battery cells are preferably provided in the base and/or in the cover. The base is preferably cup-shaped.
The elastic intermediate unit preferably encompasses a plurality of passthrough openings, each passthrough opening being configured for reception of a battery cell. The battery cells are thereby surrounded by the elastic intermediate unit. Each passthrough opening is configured for reception of a single battery cell. Before the preload force is exerted there exists, between the passthrough openings of the elastic intermediate unit and the inserted individual battery cells, a respective annular interstice that disappears after the preload force is exerted.
According to a further preferred example embodiment of the present invention, the elastic intermediate unit has a plurality of elastic individual elements. As a result, the weight of the elastic intermediate unit can be significantly reduced and an installation space required for the elastic intermediate unit can be minimized.
Alternatively, the elastic intermediate unit encompasses exactly one single individual part having a plurality of clamping regions. The clamping regions are configured to clamp the plurality of battery cells. The operation of clamping the battery cells preferably takes place between the housing and the clamping regions. A plurality of connecting regions connects the clamping regions to one another.
According to a further preferred example embodiment of the present invention, the battery cell holder further encompasses a bracing element. The elastic intermediate unit is disposed on the bracing element. The bracing element serves to support the elastic intermediate unit. If a plurality of elastic individual elements are provided, the bracing element also serves to support the individual elastic individual elements.
The elastic intermediate unit is preferably immobilized on the bracing element. This is preferably accomplished by adhesive bonding or welding or the like. Also preferably, the elastic intermediate unit and the bracing element constitute a two-constituent component made up of an inelastic carrier element with an elastic intermediate component overmolded onto the carrier element. In particular, individual elastic individual elements, or a single individual part, can be overmolded onto the inelastic carrier element.
According to a further preferred example embodiment of the present invention, the elastic intermediate unit has auxiliary holes. Alternatively, the elastic intermediate unit has no holes or the like.
Also preferably, the bracing element has a plurality of passthrough openings, each passthrough opening being configured to receive one battery cell. As a result, the battery cells can be prepositioned in the passthrough openings of the bracing element in the context of assembly.
Also preferably, the battery cell holder encompasses at least one electrical contacting element that is disposed on the elastic intermediate unit and is configured to electrically contact a battery cell on its enveloping surface. Preferably, a plurality of electrical contacting elements are provided. The electrical contacting element is a voltage-carrying element, for example a cable, FPC, or a sub-region of a circuit board. Upon expansion of the elastic intermediate element, the electrical contacting element also becomes pressed against the cell body of the battery cell, and the latter can thereby be permanently contacted if the battery cell does not have an insulating enveloping surface or if it has an opening or the like in the insulating enveloping surface. Individual battery cells can thereby be contacted, or electrical contacting to parallel-connected battery-cell groupings having the same potential can be enabled, so that an entire battery system can be monitored.
The present invention furthermore relates to a battery system encompassing a plurality of battery cells and a battery cell holder according to the present invention.
The battery system in accordance with an example embodiment of the present invention preferably encompasses a cooling device that delivers a cooling medium into the housing. It is particularly preferred if the elastic intermediate unit encompasses the first and the second elastic element, so that cooling medium can flow into an interstice formed at the battery cells by the first and the second elastic element, and can cool the battery cells. In particular if the cooling medium is a liquid medium and not air, a sealed cooling space can be furnished at the battery cells by the first and the second elastic element of the elastic intermediate unit, thereby enabling reliable sealing.
The simple and weight-optimized construction of the battery system makes the battery system according to the present invention particularly suitable for electric bicycles.
Preferred exemplifying embodiments of the present invention are described in detail below with reference to the figures,
A battery system 1 having a battery cell holder 2 will be described in detail below with reference to
In the installed state, as is evident from
Battery cells 7 are cylindrical battery cells and can be, for example, lithium ion cells.
Battery cell holder 2 further encompasses an elastic intermediate unit 4 as well as a preload device 5. Elastic intermediate unit 4 of this exemplifying embodiment encompasses a first elastic element 41 and a second elastic element 42. A plurality of passthrough openings 40 are provided respectively in first elastic element 41 and in second elastic element 42. As is evident from
In this example, preload device 5 is a clip-like clamp that exerts a preload force F1 on housing 3. As depicted schematically in
As is evident from
As already explained above, preload device 5 causes preload force F1 to be transferred to housing 3. Because housing 3 is manufactured from an inelastic material, this preload force F1 becomes transferred to first and second elastic elements 41, 42 of elastic intermediate element 4. Bracing element 6 serves here as a support. This results simultaneously in an elastic deformation of first and second elastic elements 41, 42, as indicated in
Even large manufacturing-related tolerances of battery cells 7, in particular in terms of their circumference and/or length, can thereby be compensated for. As a comparison between
Because of the elastic deformation of the first and the second elastic element, first and second elastic elements 41, 42 thus also abut sealingly against battery cells 7 (see
In addition, improved thermal heat dissipation compared with the related art can be achieved, since a thermal conductivity of the elastic intermediate unit 4, if the latter is manufactured, e.g., from a polymer, is considerably better (A polymer approx. 0.2 W/mK) than, for example, a thermal conductivity of air (A air approx. 0.0024 W/mK).
The use of elastic intermediate unit 4 furthermore makes possible improved partitioning of the individual battery cells from one another and also with respect to the environment, for instance if hot gases and/or liquids emerge from the individual battery cells 7 in the event of a fault. The safety of battery system 1 can thus additionally be improved.
For illustration,
As is further evident from
Secure holding of the individual battery cells 7, and decoupling from external influences, is furthermore achieved by way of the dual retention via first and second elastic elements 41, 42.
This exemplifying embodiment otherwise corresponds to the preceding exemplifying embodiment, so that reference may be made to the description provided there.
As is evident from the section view of
As is further evident from
Preload device 5 of the third exemplifying embodiment encompasses pin elements 50 that are visible in detail in
Be it noted that preload force F1 can be applied in different ways onto pin elements 50. Separate additional preload devices can be provided for that purpose, for example, or projections or springs or the like can be disposed on a housing (not shown in
This exemplifying embodiment otherwise corresponds to the preceding exemplifying embodiment, so that reference may be made to the description provided there.
Be it noted, alternatively to the exemplifying embodiment of
Easy voltage monitoring of battery cells 7 can thus be performed, for example. Electrical contacting elements 70 are preferably cables, or parts of a circuit board, or metallic tabs, or the like.
Number | Date | Country | Kind |
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102018220687.2 | Nov 2018 | DE | national |
102019211359.1 | Jul 2019 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2019/079546 | 10/29/2019 | WO | 00 |