Safety arrangement for a motor vehicle
A safety arrangement for a motor vehicle includes an electrical energy storage unit. The arrangement is particularly intended for use in a motor vehicle configured to be powered electrically, or by a so-called hybrid motor, and which hence comprises a high voltage electrical storage unit such as a battery or capacitor. The safety arrangement is configured to cool the storage unit in response to a signal indicative of an accident situation or battery malfunction, and comprises: a source of compressed inert gas and a flow-release actuator, the flow-release actuator being actuable upon receipt of an actuation signal so as to release a flow of inert gas from said source, the arrangement being configured such that said flow is directed substantially onto said storage unit so as to cool the unit.
1. A safety arrangement for a motor vehicle comprising:
an electrical energy storage unit;
a source of compressed non-conductive gas;
a flow-release actuator, the flow-release actuator being actuable upon receipt of an actuation signal so as to release a flow of gas from the source, the arrangement being configured such that the flow is directed substantially onto the storage unit so as to cool the unit; and
a cutting mechanism operable under action of the flow of gas to sever a conductor electrically connecting the storage unit to circuitry provided within the vehicle.
2. The safety arrangement according to claim 1 , wherein the flow-release actuator comprises a pyrotechnic charge arranged to open an outlet from the source of compressed gas upon ignition.
3. The safety arrangement according to claim 1 , further comprising at least one flow duct arranged to direct the flow of gas onto the storage unit, the arrangement being configured to combine a secondary flow of ambient air with the flow of gas.
4. The safety arrangement according to claim 1 , configured for use with an electrical storage unit of a type comprising a plurality of sub-units electrically connected in series, the safety arrangement comprising a mechanism operable under action of the flow of gas to electrically disconnect the sub-units from one another.
5. The safety arrangement according to claim 4 , wherein the mechanism is configured to electrically connect at least one of the sub-units across a discharge resistor substantially simultaneously with electrical disconnection of the sub-units from one another.
6. The safety arrangement according to claim 1 , wherein the cutting mechanism comprises a knife arranged to be driven under action of the flow of gas from a first position in which it is substantially clear of the conductor, to a second position, the knife being arranged so as to cut the conductor during movement from the first position to the second position.
7. The safety arrangement according to claim 6 , wherein the knife is substantially non-conductive.
8. The safety arrangement according to claim 3 , having at least one venturi arrangement comprising a primary flow passage having a constriction to accelerate the flow of gas, and an air inlet, the venturi arrangement being configured to draw ambient air through the inlet.
9. The safety arrangement according to claim 8 , wherein the energy storage unit is provided within a housing, and each venturi arrangement forms at least part of a nozzle arranged to direct the flow of gas, and the flow of ambient air through the housing.
10. The safety arrangement according to claim 4 , wherein the mechanism comprises a piston arranged to move from an initial position to an operative position under action of the flow of gas, the piston being arranged to break electrical connection between the sub-units during movement from the initial position towards the operative position.
11. The safety arrangement according to claim 10 , provided in combination with an electrical storage unit, the safety arrangement configured such that each pair of adjacent sub-units are electrically connected via a pair of contacts, each contact extending from a respective sub-unit and initially making electrical contact with the other contact, wherein the piston is arranged to deform or move the contacts out of electrical contact with one another as it moves from the initial position to the operative position.
12. The safety arrangement according to claim 11 , wherein the mechanism is configured to electrically connect at least one of the sub-units across a discharge resistor substantially simultaneously with electrical disconnection of the sub-units from one another, the arrangement being configured such that movement of the piston from the initial position to the operative position is effective to deform or move each contact into electrical connection with a discharge resistor.
13. The safety arrangement according to claim 1 , wherein the energy storage unit comprises either a capacitor or a battery.
14. The safety arrangement according to claim 1 , in combination with a motor vehicle, wherein the motor vehicle is an electric vehicle or a hybrid vehicle.