Chemistry: electrical current producing apparatus – product – and – With measuring – testing – or indicating means – For charge or liquid level
Reexamination Certificate
1998-10-19
2001-10-02
Brouillette, Gabrielle (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
With measuring, testing, or indicating means
For charge or liquid level
C429S090000, C429S062000, C429S186000, C429S163000
Reexamination Certificate
active
06296966
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns a one-piece battery comprising a device adapted to measure the temperature of the electrode assemblies contained in the compartments of the battery.
2. Description of the Prior Art
In a one-piece design the cells of the battery are contained in the compartments of a single container separated by partitions. The container is generally made of a plastics material and prism-shaped. Each cell comprises an electrode assembly of alternating positive and negative electrodes separated from each other by a separator.
The temperature of the electrode assembly varies during successive charging and discharging cycles. The charging (or discharging) time can be monitored by measuring the temperature. The accuracy with which the end of charging is detected depends on the quality of the temperature measurement. This reduces overcharging and extends the service life of the battery. Also, if a malfunction occurs the temperature of the electrode assembly can rise suddenly. The safety of the user depends on how quickly the thermal anomaly can be detected. Also, a one-piece battery is generally associated with a cooling device whose efficiency must be monitored.
The measurement is routinely performed by a temperature sensor fixed to one of the external faces of the one-piece battery by an adhesive. A sensor located in this position cannot measure the real temperature of the electrode assemblies and is exposed to all the thermal disturbances external to the battery. There is also the risk of the sensor becoming detached from the wall of the container.
Document EP-0 638 951 describes a one-piece battery to which an end compartment is added to accommodate a safety device including a temperature sensor. The sensor is supported by a lipped member upstanding from the partition separating the end compartment from the adjacent compartment containing an electrode assembly. This arrangement has a number of drawbacks. Firstly, the accuracy with which the temperature is measured in this way is insufficient. In this position the compartment at the end of the battery is exposed to external temperature variations. The sensor reacts to variations in the temperature of the adjacent electrode assembly but it is less sensitive to the temperature of the other electrode assemblies. Secondly, temperature variations are detected with a time-delay. The thermal path between the electrode assembly and the sensor is long, especially for the electrode assemblies at the other end of the battery. Adding the end compartment significantly increases the overall size of the battery and reduces its capacity per unit volume.
Document EP-0 739 048 proposes placing a temperature sensor in an orifice terminating near the upper part of the electrode assembly, the orifice being closed off by an adhesive. The distance between the sensor and the upper part of the electrode assembly can vary according to the dimensional tolerances for the height of the electrodes. Although this arrangement can measure a temperature very close to the real temperature of the electrode assembly, heat transfer only by radiation cannot detect temperature variations with sufficient accuracy. The composition of the gas mixture above the electrode assembly varies during cycling, is richer in hydrogen at the end of charging and can change if the relief valve opens. The volume occupied by the temperature measuring device is still too great.
There is a need for a one-piece battery with a capacity per unit volume at least equal to that of existing batteries and with an extended service life. The battery must also be safer for users.
An aim of the present invention is to propose a one-piece battery including a smaller device for measuring the temperature of the electrode assemblies so that the internal temperature is measured and its variations are monitored more reliably, faster and more accurately than in prior art batteries.
SUMMARY OF THE INVENTION
The present invention consists in a sealed one-piece battery comprising a container having a wall and divided into contiguous compartments adapted to receive electrode assemblies by a partition attached to the wall and a device for measuring the temperature of the electrode assemblies comprising measuring means disposed in a housing formed within the thickness of at least one of the partitions so that the opening of the housing is on the external face of the wall.
The electrode assemblies are placed in the compartments in contact with the partitions. The heat generated within the electrode assembly is transferred to its external surface, in particular by the electrolyte that impregnates the electrodes and the separator. Heat transfer from the electrode assembly to the measuring means is effected principally by conduction in the part of the compartment in direct contact with the electrode assembly. In the part of the partition above the electrode assembly it is additionally effected by indirect contact through the intermediary of the separators that are impregnated with electrolyte and/or by radiation.
Each compartment is therefore exposed to changes in the temperature of the electrode assemblies on either side of it. The housing formed within the thickness of a partition is therefore in close thermal contact with the surface of the adjacent electrode assemblies. Its temperature is practically the same as that of the electrode assemblies and changes immediately with the least variation therein because the heat path is short. The measuring means disposed therein therefore provide an accurate measurement of the instantaneous temperature of the electrode assemblies. The part of the housing containing the sensitive part of the measuring means is entirely contained within the partition: there is no contact with the exterior of the container and it is not exposed to thermal disturbances of the environment.
Creating the housing does not increase the volume of the battery. The the level of the top face of the electrode assembly, so occupying a space that is usually unoccupied. To obtain the most accurate possible temperature measurement without reducing its capacity per unit volume the battery can be equipped with a plurality of judiciously distributed housings each containing measuring means.
Access to the housing is obtained from the exterior face of the wall, in line with the partition. The measuring means are therefore accessible at all times from the exterior of the battery. They can therefore be checked or changed easily, if required.
The measuring means can comprise a temperature sensor, for example a transistor or a thermocouple. Their end can be of circular, oval, square or rectangular section, for example.
To minimize the additional thickness of the partition at the location of the housing, its end is preferably flattened. The general shape of the housing can therefore be that of a rectangular parallelepiped with straight or curved shorter sides and with the longer sides parallel to the faces of the partition.
To reduce further the size of the measuring means at the level of the electrode assembly the end of the sensor entering the housing can be extended by a thermal conductor of smaller size, the function of which is to transmit heat to the sensor. The conductor preferably has a small cross-section and can be flattened.
In a preferred embodiment said wall is horizontal. This enables the one-piece batteries to be assembled together with their vertical faces in contact. In this case the horizontal top face of the batteries can carry not only the openings of the housings containing the temperature measuring means but also the current input and output terminals, one or more orifices for filling them with electrolyte, relief valves protecting against overpressure, inlet and outlet tubes for the heat-conveying fluid, etc.
Said wall and said portion are preferaby in one piece. The walls and the partitions of the container are molded in one piece. After the electrode assemblies are inserted the bottom, which is initially a separate part, is f
Genton Alain
Verhoog Roelof
Alcatel
Alejandro Raymond
Brouillette Gabrielle
Sughrue Mion Zinn Macpeak & Seas, PLLC
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