WO2003019700A1

WO2003019700A1 - A battery and a battery encapsulation

Info

Publication number: WO2003019700A1
Application number: PCT/SE2002/001178
Authority: WO
Inventors: Kenneth Dahlberg
Original assignee: St. Jude Medical Ab
Priority date: 2001-08-30
Filing date: 2002-06-17
Publication date: 2003-03-06
Also published as: SE0102917D0; US7241531B2; US20050019653A1

Abstract

A battery unit comprising a battery (2), and a battery encapsulation (3), comprising first and second encapsulation parts (4, 5) joined by a weld along a weld zone (14), the battery (2) being located in the encapsulation (3). The battery (2) comprises a recess (11) extending along the weld zone (14), such that a heat insulating space (12) is formed between the battery (2) and the encapsulation (3) along the weld zone (14).

Description

A battery and a battery encapsulation

TECHNICAL FIELD

The present invention relates to a battery adapted to be located in a battery encapsulation, comprising a first and a second encapsulation part joined by a weld along a weld zone.

The invention also relates to such a battery encapsulation, and a battery unit comprising such a battery and such a battery encapsulation, the battery being located in the encapsulation.

The invention also relates to an implantable medical device that comprises a battery unit according to the invention. Typically, the implantable medical device is a heart stimulating apparatus.

It should be noted that the invention particularly relates to a battery unit, a battery and a battery encapsulation where the first and second encapsulation parts are joined by means of welding while the battery is present in the encapsulation, generally in its operative position in the encapsulation.

BACKGROUND OF THE INVENTION AND PRIOR ART

Since the invention is particularly applicable to batteries and battery units of implantable medical devices such as heart stimulating apparatuses the background of the invention is described with reference to such an application.

Batteries for implantable medical apparatuses are encapsulated in encapsulations made of a material compatible with the human body. Such materials comprise metals such as stainless steel or titanium. The encapsulation is constituted of two or more parts that have to be joined with the battery positioned inside the encapsulation. Preferably the encapsulation parts are joined by means of welding along overlapping edges thereof.

Welding will result in heat being generated in the very vicinity of the battery itself. Normally, the battery is covered with an electrically insulating material, for example a polymer. The heat might negatively affect the battery or the insulating material covering it since the battery is located close to the weld during the welding.

The traditional way to solve this problem is to use a support element, usually a polymer structure that separates the battery from the encapsulation in the weld region. The support element may comprise a recess opposite the weld, thereby providing a clearance between itself and the weld zone or weld region. Thereby, it prevents heat transfer through conduction directly to the support element and the battery. However, some space that could otherwise have been used as battery space is lost in the encapsulation due to the presence of the support element. The support element also adds cost to the battery unit.

BRIEF DESCRIPTION OF THE INVENTION

It is an object of the present invention to present a battery unit consisting of a battery and a battery encapsulation of the type initially denned that permits better use of space for the battery in the encapsulation than in units of prior art, while at the same time permitting welding together the encapsulation parts with the battery in place without damaging the battery or any insulating material deposited thereon because of heat emanating from the weld. It is a further object of the present invention to present a battery unit comprising a battery and a battery unit of the type initially defined that is advantageous to manufacture from an economical point of view.

The object of the invention is achieved by means of the initially defined battery, characterised in that the battery comprises a recess extending along a region corresponding to the weld zone, such that a heat insulating space is formed between the battery and the encapsulation along the weld zone.

The recess is located opposite to the weld zone, the depth and width of the recess being adapted such that heat emanating from the weld zone during welding does not have any detrimental effect on the battery.

According to a preferred embodiment, the battery is covered by an (electrically) insulating material, the depth and width of the recess being adapted such that heat emanating from the weld zone during welding does not have any detrimental effect on the insulating material.

The object of the invention is also achieved by means of a battery encapsulation of the type initially defined, characterised in that, along the weld zone, portions of the first and second encapsulation parts are bent away from a battery located in the encapsulation such that a heat insulating space is formed between the battery and the encapsulation along the weld zone.

Said portions are bent away to such an extent that heat emanating from the weld zone during welding does not have a detrimental effect on the battery or any electrically insulating material deposited on the battery.

Said portions extend along the complete length of the weld zone, or at least the or those parts of the weld zone that faces the battery.

As a direct consequence of what has been described above, the invention also relates to a battery unit as initially defined, characterised in that it comprises the battery according to the invention.

The invention also relates to an implantable medical device that is characterised in that it comprises a battery unit according to the invention. According to one embodiment the implantable medical device is a heart stimulating apparatus.

Further features and advantages of the present invention are presented in the following, detailed description and in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, embodiments of the invention will be described by way of example, with reference to the accompanying drawings, on which:

Fig. 1 is a perspective view showing a battery unit,

Fig. 2 is a cross sectional view of a part of the battery unit in fig. 1 according to prior art, Fig. 3 is a cross sectional view of the same part of the battery unit shown in fig. 1 , but according to a first embodiment of the invention,

Fig. 4 is a cross sectional view of a part of the same part of the battery unit shown in fig. 1 , but according to a second embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In fig. 1 there is shown a battery unit 1 a part of which is shown in a cross sectional view in detail according to prior art and different embodiments in figs. 2-4.

Here, the battery unit 1 is part of an implantable medical device, more precisely a heart stimulating apparatus such as a pacemaker to be implanted in a mammal.

The battery unit 1 comprises a battery 2 enclosed in an encapsulation 3 comprising a first and a second part 4,5 that are joined by a weld 13, preferably accomplished by laser welding. The battery 2 occupies a part of the interior of the encapsulation 3, while another part of the encapsulation interior is occupied by electronics (not shown) for controlling the operation of the device. On top of the battery unit 1 and fixed thereto there is also provided a body 15, normally made of a transparent polymer, defining a connector body with connector elements (not shown) for the connection of leads to the battery 2.

The first and second parts 4,5 of the encapsulation 3 are joined along opposite edges 6,7 thereof. The edges 6,7 overlap each other along the weld 13. One edge 6 is displaced inwards with a distance corresponding to the thickness of the walls of the encapsulation parts 4. Thereby a generally flat outer periphery of the small sides of the encapsulation 3 is obtained, as well as an inner protuberance.

In fig. 2 there is shown a battery unit according to prior art, by which there is provided a support element 8 for the battery 2 in the encapsulation 3. The support element 8 defines a distance holder between the battery 2 and the encapsulation all along the weld zone. In the support element 8 there is provided a recess 9 opposite the weld zone 14 and extending over the length of the weld zone 14 that it faces. The support element 8 is usually made of a polymer. The recess creates a space between heat affected encapsulation 3 and battery 2 that prevents excessive heat transfer from the weld zone 14 to the battery 2 or any electrically insulating coating 10 on the battery 2 during welding.

The battery is made of metal, such as stainless steel, and the insulating coating material 10 is preferably a polymer such as silicon rubber, polypropylene (PP), polyfluorethylene or any other suitable electrically insulating material.

The encapsulation 3 is preferably made of a material accepted by the human body, such as titanium or stainless steel.

As an alternative to the battery unit 1 according to fig. 2 prior art also suggests battery units without any support element. Such a battery unit is shown in fig. 3 and has the disadvantage of excessive heat being transferred from the weld zone to the battery 2 during welding. The transferred heat may damage the battery 2 or any coating of electrically insulating material 10 provided thereon.

Fig. 3 shows a first embodiment of the inventive battery unit 1. Here, the battery 2 comprises a recess 1 1 extending along a region corresponding to the weld zone 14 adjacent the battery 2, such that a heat insulating space 12 is formed between the battery 2 and the encapsulation 3 along said part of the weld zone 14. Thereby excessive heat transfer is prevented from damaging the battery 2 or its insulation material 10. It is evident that only the part of the battery 2 that is facing the weld zone 14 need be provided with the recess 11. Normally, at least three out of the four of a generally flat, rectangular battery's small sides need be provided with said recess. The fourth small side of the battery that faces the electronics mentioned above could be spared from such a recess, if preferred from a production cost saving point of view.

The length of the recess 11 corresponds to the length of the part of the weld 13 that it faces. The depth of the recess 1 is such that an insulating space of 0,05 to 0,30 mm is obtained between the inner periphery of the weld zone 14 of the encapsulation 3 and the battery 2. One of the overlapping edges 6,7 is displaced inwards with a distance corresponding to the thickness of the encapsulation wall in order to provide a generally flat outer periphery along the joint between the encapsulation parts 4,5. Thereby, the actual depth of the recess in this embodiment is equal to the encapsulation wall thickness plus 0,05-0,30 mm.

The width of the recess is at least 0,2 to 0,6 mm larger than the width of the weld zone 14. Preferably, the width of the recess is 0,2-0,6 mm larger than the width of the overlapping edge 6 that protrudes inwards towards the battery 2. Thereby a preferred lateral spacing of 0, 1 to 0,3 mm is created between battery 2 and encapsulation 3 on each side of the overlapping part of the edges 6,7 or, more precisely, the protuberance formed by the inner edge 6. Fig. 4 shows a second embodiment of the inventive battery unit 1. Here, the recess in the battery 2 has been replaced by a corresponding convexity of the edges 6,7 of the encapsulation. That is, the edges 6,7 are pre-bent before welding such that, with a conventional flat battery 2 inside the encapsulation 3, there will be an insulating space 12 between the battery 2 and inner periphery of the encapsulation along the weld zone 14.

The edges 6,7 are bent away from the interior of the encapsulation to such an extent that the heat insulating space thereby obtained has a width and a depth corresponding to the one mentioned above for the first embodiment.

It should be understood that the above embodiments only have been disclosed by way of example, and that the invention is not restricted to these embodiments. A plurality of alternative embodiments will be obvious for a man skilled in the art without thereby going beyond the scope of the invention as claimed in the appended claims, supported by the description and the accompanying drawings.

For example, in the first embodiment, the small sides of the encapsulation 3 that faces the battery 2 protrude inwards along the overlapping portions 6,7, whereby the heat insulating space between battery and enclosure is obtained thanks only to the provision of the recess in the battery. In the second embodiment on the other hand, the heat insulating space is provided through the provision of the bent encapsulation edge portions 6,7, the small sides of the battery 2 directed thereto being generally flat (without recess). It should be understood that a combination of the first and second embodiments of the invention as described above is comprised by the scope of the invention as long as the insulating space thereby created corresponds to the one defined above for each single embodiment. The term "weld zone" as used herein refers to at least a region of the encapsulation located adjacent to the weld, the structure of which is visibly or at least physically altered due to the heat it is exposed to during welding.

Claims

PATENT CLAIMS

1. A battery (2) adapted to be located in a battery encapsulation (3), comprising a first and second encapsulation part (4,5) joined by a weld (13) along a weld zone, characterised in that the battery (2) comprises a recess (11) extending along a region corresponding to the weld zone (14), such that a heat insulating space (12) is formed between the battery (2) and the encapsulation (3) along the weld zone (14).

2. A battery according to claim 1, characterised in that the recess (11) is located opposite to the weld zone (14), the depth and width of the recess (11) being adapted such that heat emanating from the weld zone (14) during welding does not have any detrimental effect on the battery (2).

3. A battery according to claim 1 or 2, characterised in that it is covered by an insulating material (10), the depth and width of the recess (1 1) being adapted such that heat emanating from the weld zone (14) during welding does not have any detrimental effect on the insulating material (10).

4. A battery according to any one of claims 1-3, characterised in that the length of the recess (11) corresponds at least to the length of the or those parts of the weld zone (14) that faces the battery (2).

5. A battery according to any one of claims 1-4, characterised in that the depth of the recess (1 1) is such that the distance between battery (2) and the inner periphery of the encapsulation along the weld zone (14) is 0,05 to 0,30 mm.

6. A battery according to any one of claims 1-4, characterised in that the width of the recess (11) is 0,2-0,6 mm larger than the width of the weld zone (14).

7. A battery according to any one of claims 1-5, characterised in that the encapsulation comprises overlapping edges (6,7) that are welded together by means of said weld (13), and that the width of the recess (1 1) is 0,2 to 0,6 mm larger than the width of the overlapping part of the edges (6,7), a lateral spacing of 0, 1 to 0,3 mm being created between battery (2) and encapsulation (3) on each side of the overlapping part of the edges (6,7).

8. A battery according to any one of claims 1-7, characterised in that it is a battery for a heart stimulating apparatus to be located in a mammal.

9. A battery encapsulation (3), comprising first and second encapsulation parts (4,5) joined by means of a weld along a weld zone

(14), characterised in that, along the weld zone (14), portions (6,7) of the first and second encapsulation parts (4,5) are bent away from a battery (2) located in the encapsulation (3) such that a heat insulating space (12) is formed between the battery (2) and the encapsulation (3) along the weld zone (14).

10. A battery encapsulation according to claim 9, characterised in that said portions (6,7) are bent away to such an extent that heat emanating from the weld zone (14) during welding does not have a detrimental effect on the battery (2).

1 1. A battery encapsulation according to claim 9 or 10, characterised in that the battery (2) is covered by an insulating material (10), and that said portions (6,7) are bent away to such an extent that heat emanating from the weld zone (14) during welding does not have a detrimental effect on the insulating material (10).

12. A battery encapsulation according to any one of claims 9- 11 , characterised in that said portions (6,7) extend along at least the part or parts of the weld zone (14) that faces the battery (2).

13. A battery encapsulation according to any one of claims 9-12, characterised in that the depth of the heat insulating space (12) is 0,05-0,30 mm.

14. A battery encapsulation according to any one of claims 9- 13, characterised in that the width of the heat insulating space (12) is 0,2-0,6 mm larger than the width of the weld zone (14).

15. A battery encapsulation according to any one of claims 8- 14, characterised in that it is adapted to encapsulate a battery (2) for a heart stimulating apparatus to be located in the body of a mammal.

16. A battery unit comprising a battery (2), and a battery encapsulation (3), comprising first and second encapsulation parts (4,5) joined by a weld along a weld zone (14), the battery (2) being located in the encapsulation characterised in that the battery (2) comprises a recess (1 1) extending along the weld zone (14), such that a heat insulating space (12) is formed between the battery (2) and the encapsulation (3) along the weld zone (14).

17. A battery unit according to claim 16, characterised in that the recess (11) is located opposite to the weld zone (14), the depth and width of the recess (1 1) being adapted such that heat emanating from the weld zone (14) during welding does not have any detrimental effect on the battery (2).

18. A battery unit according to claim 16 or 17, characterised in that the battery (2) is covered by an insulating material (10), the depth and width of the recess (1 1) being adapted such that heat emanating from the weld zone (14) during welding does not have any detrimental effect on the insulating material (10).

19. A battery unit according to any one of claims 16- 18, characterised in that the length of the recess (1 1) corresponds to at least the length of the part or parts of the weld zone (14) that faces the battery (2).

20. A battery unit according to any one of claims 16-19, characterised in that the depth of the recess (11) is such that the distance between the inner periphery of the encapsulation along the weld zone (14) and the battery (2) is 0,05 to 0,30 mm.

21. A battery unit according to any one of claims 16-20, characterised in that the width of the recess (11) is 0,2-0,6 mm larger than the width of the weld zone (14).

22. A battery unit according to any one of claims 16-20, characterised in that the encapsulation comprises overlapping edges (6,7) that are welded together by means of said weld (13), and that the width of the recess (11) is 0,2 to 0,6 mm larger than the width of the overlapping part of the edges (6,7), a lateral spacing of 0, 1 to 0,3 mm thereby being created between battery (2) and encapsulation on each side of the overlapping part of the edges (6,7).

23. An implantable medical device, characterised in that it comprises a battery unit (1) according to any one of claims 16-22.

24. An implantable medical device according to claim 23, characterised in that said medical device is a heart stimulating apparatus.