Pressure relief element, pressure relief device and battery

Abstract

The present invention relates to a pressure relief element (11) to be used as an overpressure safety means in devices where a gaseous medium must be rapidly released in case of overpressure, wherein the pressure relief element (11) has at least one notch (9) which is designed as a predetermined breaking point where the pressure relief element (11) breaks at a certain level of overpressure, thereby irreversibly opening an exhaust path for the gaseous medium. The present invention also relates to a pressure relief device of an electrochemical battery, comprising such a pressure relief element and a battery comprising such a pressure relief device.

Claims

1. A battery, comprising: a plurality of battery cells disposed within a battery housing, wherein the battery housing includes a pressure relief device comprising: an exhaust extension which extends outwardly from the battery housing; and a fixation element for fixing the exhaust extension to a housing wall of the battery housing such that the exhaust extension traverses an exterior opening in the housing wall of the battery housing and is attached to the fixation element within the interior of the battery housing, wherein the exhaust extension comprises an injection molded plastic pressure relief element having: a first side having a profiled surface that is in fluid communication with an exterior of the battery housing; and a second side, opposite the first side, having a substantially flat surface that is in fluid communication with an interior of the battery housing, wherein the second side comprises a notch that is a predetermined breaking point where the pressure relief element is configured to break at a certain level of overpressure of a gaseous medium in the battery housing, thereby irreversibly opening an exhaust path for the gaseous medium to rapidly exit the battery housing.

2. The battery of claim 1, wherein the injection molded plastic pressure relief element is formed as a plate-like and/or disc-like part.

3. The battery of claim 1, wherein the first side is an injection side of the of the injection molded plastic pressure relief element.

4. The battery of claim 1, wherein a thickness of the injection molded plastic pressure relief element is larger in a central area of the injection molded plastic pressure relief element than in at least one area surrounding the central area.

5. The battery of claim 4, wherein the thickness of the injection molded plastic pressure relief element decreases in a steadily declining manner from the central area towards the at least one area surrounding the central area.

6. The battery of claim 1, wherein the injection molded plastic pressure relief element comprises a circumferential area of increased material thickness on its outer circumference.

7. The battery of claim 6, wherein the notch is located close to the circumferential area with increased material thickness.

8. The battery of claim 1, wherein the notch is shaped as a circumferential notch, which surrounds a central area of the injection molded plastic pressure relief element.

9. The battery of claim 1, wherein the plastic material of the pressure relief element is a rigid plastic material.

10. The battery of claim 1, wherein the pressure relief element is a membrane.

11. The battery of claim 1, wherein the exhaust extension comprises a tube that is mounted by a tube connector and that allows constant pressure equalization between the interior and the exterior of the battery housing while the injection molded plastic pressure relief element remains intact.

12. The battery of claim 1, wherein the exhaust extension comprises a protection cap or maze that at least partly shields the pressure relief element against an environment exterior to the battery housing.

13. The battery of claim 1, wherein the plurality of battery cells are lithium ion battery cells.

14. The battery of claim 1, wherein the plurality of battery cells are cylindrical battery cells.

15. A battery, comprising: a plurality of battery cells disposed within a battery housing, wherein the battery housing includes a pressure relief device, comprising: an injection molded plastic pressure relief element comprising: a first side having a profiled surface that is in fluid communication with an exterior of the battery housing; and a second side, opposite the first side, having a substantially flat surface that is in fluid communication with an interior of the battery housing, wherein the second side comprises a notch that is a predetermined breaking point where the pressure relief element is configured to break at a certain level of overpressure of a gaseous medium in the battery housing, thereby irreversibly opening an exhaust path for the gaseous medium to rapidly exit the battery housing; and a tube that is mounted by a tube connector and that allows constant pressure equalization between the interior and the exterior of the battery housing while the injection molded plastic pressure relief element remains intact.

Description

DRAWINGS

(1) The invention is now further described through exemplary embodiments and through drawings.

(2) The drawings show:

(3) FIG. 1 show a battery with a plurality of electrochemical cells and

(4) FIG. 2 show a pressure relief device with integrated pressure relief element and

(5) FIGS. 3-5 show another embodiment of a pressure relief device with integrated pressure relief element and

(6) FIGS. 6 and 7 show a pressure relief element and . . . .

(7) FIGS. 8 and 9 show another embodiment of a pressure relief device.

(8) In the drawings same numerals refer to same elements . . . .

DETAILED DESCRIPTION

(9) FIG. 1 shows an electrochemical battery 1 comprising a battery housing 2 and a plurality of electrochemical cells 3, which are located within the battery housing 2. The electrochemical cells 3 comprise own cell housings. The electrochemical cells 3 may be provided in the form of prismatic or cylindrical cells or any other suitable cell format. The housing 2 can be designed, as depicted in FIG. 1, like a bin or a tray. For applications in vehicles the housing 2 is normally made of metal material, but can also be made of lighter materials like resin or other plastic materials.

(10) On the outside of the housing 2 a pressure relief device 4 is mounted. The pressure relief device 4 comprises a tube-like exhaust extension 7 which is fixed to the housing on a wall 6 of the housing 2. The exhaust extension 7 extends from the housing 2 of the battery 1 outwards and provides for a breathing channel between the interior of the housing 2 and the exterior, allowing air and moisture to exchange between the interior and the exterior of the housing 2. Further, in case of an overpressure within the housing 2, gases from the cells 3 could be released through the exhaust extension 7. The pressure relief device 4 comprises a pressure relief element 11 which is mounted on the outside of the exhaust extension 7. The pressure relief element 11 comprises an outer wall 8 which has a notch 9 which serves as a predetermined breaking point where the pressure relief element 11 breaks at a certain level of overpressure within the housing 2. The pressure relief device 4 comprises a tube connector 10 for mounting the tube 5, as shown in FIG. 1. The tube connector 10 can be located at the end of the pressure relief element 11 beyond the notch 9. As can be seen, the cross-section of the tube connector 10 as significantly smaller than the cross-section of the exhaust extension 7, which makes it necessary to provide the predetermined breaking point for safety reasons.

(11) In the FIGS. 3 to 5 another embodiment of a pressure relief device 4 mounted to the housing wall 6 is depicted in different views. As can be seen, the pressure relief device 4 again comprises an exhaust extension 7 in similar manner as shown in FIG. 2. On the exhaust extension 7 a tube-like element with an outer wall 8 is mounted. On the outer wall 8 a tube connector 10 is located. Within the outer wall 8 a pressure relief device 11 in the form of a circular wall is located. The pressure relief element 11 again comprises a notch 9 as the predetermined breaking point. The notch 9 according to FIGS. 3 to 5 can be designed as a circular or semicircular groove, which completely or partially extends along the circumference of the pressure relief element 11.

(12) In the embodiment of FIGS. 1 to 5 the pressure relief device 4 can be made integrally of the same material, like plastic material. It is also possible to provide separate parts e.g. for the exhaust extension 7 and the pressure relief element 11.

(13) FIGS. 6 and 7 show an embodiment of a pressure relief element 11 as a separate part, in particular as a disk-like part made out of plastic material by an injection moulding process. FIG. 6 shows the pressure relief element 11 in an isometric view, FIG. 7 shows a cross-sectional view. As can be seen in the 30 figures, the pressure relief element 11 comprises a generally flat lower side 69 and a profiled upper side 68 which is the opposite side of the lower side 69. The upper side 68 is an injection side of the pressure relief element 11, where the plastic material is injected into an injection mould during the manufacturing process of the pressure relief element 11. The profiled injection side 68 comprises a raised central area 60 with an increased material thickness. The plastic material is injected in the area 60 into the injection mould. Going from the central area 60 outwards, the material thickness decreases through areas 61, 62 smoothly, e. g. in a declining manner, until an outer circular position 63 is reached. Going beyond the position 63, the material thickness again increases in area 64 to form a raised outer circular area 65 of the pressure relief element 10 11 which can serve as a mounting element for mounting the pressure relief element in a pressure relief device. On the generally flat lower side 69, which is the side of the pressure relief element 11 which is to be charged with a gaseous medium, a notch 9 in the form of a circular notch is provided which acts as a predetermined breaking point of the pressure relief element 11. The material 15 thickness in the area of the notch 9 is e. g. only 0.03 mm.

(14) FIGS. 8 and 9 show another embodiment of a pressure relief device 80 composed of several separate parts which can be easily mounted to one another and to the housing wall 6. Further, the pressure relief device 80 according to 20 FIGS. 8 and 9 is suitable for incorporating a pressure relief element 11 of FIGS. 6 and 7. FIG. 8 shows the completely mounted pressure relief device 80, FIG. 9 shows an explosional view of the pressure relief device 80.

(15) The pressure relief device 80 of FIGS. 8 and 9 comprises a base part 83 composed of different elements shown in FIG. 9. As can be seen in FIG. 8, a protection cap 81 is mounted on the base part 83 by snap-hook elements 82. Further it can be seen that the base part 83 comprises a tube connector 10.

(16) Going to FIG. 9, it can be seen that the pressure relief device 80 comprises 30 four separate parts plus a pressure relief element 11 according to FIGS. 6 and 7. The four elements are the already described protection cap 81 and the base element 83 comprising of a pressure relief element holder 90, a cap fixation part 91 and a fixation element 92 for mounting the pressure relief device 80 to the housing wall 6. For explanation purposes, the pressure relief element holder 90 is additionally shown in the left upper part of FIG. 9 from its bottom 5 side.

(17) The pressure relief device 80 according to FIGS. 8 and 9 can be mounted to the housing wall 6 of the housing 2 of the battery 1 in the following way. First, the pressure relief element 11 is placed on a reception side of the pressure relief element holder 90. Then the pressure relief element holder 90 with the pressure relief element 11 is placed within the cap fixation part 91 and then the protection cap 81 is fixed on the cap fixation part 91 by means of the snaphooks 82. In such way, the pressure relief element 11 is encapsulated between the pressure relief element holder 90 and the protection cap 81, while the pressure relief element holder 90 is encapsulated between the cap fixation part 91 and the protection cap 81. The unit comprising of elements 11, 81, 90, 91 can then be inserted through an opening in the housing wall 6 of the housing 2. Then, the fixation element 92 is attached to a mechanical link element 93 of the pressure relief element holder 90. The mechanical link element 93 is designed to extend through the cap fixation part 91 and the housing wall 6 to the inside of the housing 2. The mechanical link 93 can be designed e. g. as a duff-tail link.

(18) Those reviewing this disclosure will appreciate that various exemplary embodiments have been shown and described, and that according to various exemplary embodiments, features associated with one exemplary embodiment may be used with features included in other exemplary embodiments.

(19) As utilized herein, the terms approximately, about, substantially, and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the invention as recited in the appended claims.

(20) It should be noted that the term exemplary as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representations, and/or illustrations of possible embodiments (and such term is not intended to connote that such embodiments are necessarily extraordinary or superlative examples).

(21) The terms coupled, connected, and the like as used herein mean the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another.

(22) References herein to the positions of elements (e.g., top, bottom, above, below, etc.) are merely used to describe the orientation of various elements in the FIGURES. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.

(23) It is important to note that the construction and arrangement of the battery module having electrochemical cells with integrally formed terminals as shown in the various exemplary embodiments is illustrative only. Although only a few embodiments of the present inventions have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. For example, the battery may be noncylindrical (e.g., oval, rectangular, etc.), the position of elements may be reversed or otherwise varied (e.g., orientation of terminals), and the battery could be a number of different of types (e.g., nickel metal hydride, lithium ion, lithium polymer, etc.). Accordingly, all such modifications are intended to be included within the scope of the present inventions. The order or sequence of any process or method steps may be varied or re-sequenced according to exemplary embodiments. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present invention.