Firing Agent for Gas Generating Device

Abstract

A firing agent which is used in a gas generating device of a vehicle occupant protection device together with a non-azide gas generating agent, for firing the non-azide gas generating agent, wherein the firing agent contains a fuel and an oxidizing agent and is configured to burn at a combustion speed higher than that of the non-azide gas generating agent; a method for using the firing agent; and a gas generating device of a vehicle occupant protection device using the firing agent.

1 . A firing agent which is used in a gas generating device of a vehicle occupant protection device together with a non-azide gas generating agent, for firing the non-azide gas generating agent, the non-azide gas generating agent burning at a first combustion speed, the firing agent comprising:
 a fuel; and   an oxidizing agent, wherein the firing agent is configured to burn at a second combustion speed higher than the first combustion speed of the non-azide gas generating agent.   
   
   
       2 . The firing agent according to  claim 1 , wherein the first or second combustion speed is obtained by:
 accommodating the non-azide gas generating agent or the firing agent into a closed chamber equipped with an igniter;   activating the igniter;   monitoring gas pressure inside the closed chamber; and   measuring a reaching time from the time when the operation of the igniter was started to the time when the gas pressure inside the closed chamber has reached a maximum value, wherein the reaching time of the firing agent is shorter than the reaching time of the non-azide gas generating agent.   
   
   
       3 . The firing agent according to  claim 2 , wherein the reaching time of the firing agent is 5 to 20 milliseconds when the firing agent is charged into the closed chamber at a charging density of 0.059 g/ml and then ignited. 
   
   
       4 . The firing agent according to  claim 1 , wherein the firing agent has a positive oxygen balance. 
   
   
       5 . The firing agent according to  claim 1 , wherein:
 the non-azide gas generating agent has a shape defined by first plural dimensions;   the firing agent has a shape defined by second plural dimensions; and   a minimum value of the second plural dimensions is smaller than a minimum value of the first plural dimensions of the non-azide gas generating agent.   
   
   
       6 . The firing agent according to  claim 1 , wherein, when the non-azide gas generating agent is ignited, the combustion of the non-azide gas generating agent proceeds in first plural combustion directions; the non-azide gas generating agent has first plural dimensions along the first plural combustion directions; and when the firing agent is ignited, the combustion of the firing agent proceeds in second plural combustion directions, and wherein the firing agent has second plural dimensions along the second plural combustion directions, and a minimum value of the plural dimensions is smaller than a minimum value of the first plural dimensions. 
   
   
       7 . The firing agent according to  claim 5 , wherein the firing agent is used together with a non-azide gas generating agent of which minimum value of the first plural dimensions falls within the range of 0.3 to 4 mm, and a minimum value of the second plural dimensions falls within the range of 0.01 to 3 mm. 
   
   
       8 . The firing agent according to  claim 5 , wherein the firing agent and the non-azide gas generating agent are in the form of grains or powder. 
   
   
       9 . The firing agent according to  claim 5 , wherein the firing agent is in the form of grains, and a minimum value of the second plural dimensions falls within the range of 0.01 to 3 mm. 
   
   
       10 . The firing agent according to  claim 5 , wherein the firing agent is in the form of:
 a column having an axial line, an outer diameter of 0.1 to 2 mm, and a length alone the axial line of 0.1 to 3 mm; or   a hollow body having an axial line, an outer diameter, a length along the axial line, a hole extending alone the axial line, and a side surface, the outer diameter being 0.3 to 3 mm, the length being 0.1 to 3 mm, the hole diameter being 0.1 to 1 mm, the thickness from the side surface to the hole being 0.1 to 1.5 mm.   
   
   
       11 . The firing agent according to  claim 10 , wherein the hole is one of plural holes. 
   
   
       12 . The firing agent according to  claim 1 , wherein the non-azide gas generating agent contains a perchlorate oxidizing agent, fuel, and a chlorine remover, and
 wherein the oxidizing agent of the firing agent is a perchlorate oxidizing agent.   
   
   
       13 . The firing agent according to  claim 1 , wherein the non-azide gas generating agent contains an ammonium salt oxidizing agent and fuel, and
 wherein the oxidizing agent of the firing agent is potassium salt.   
   
   
       14 . The firing agent according to  claim 1 , wherein the oxidizing agent of the firing agent is nitrate, nitrite, or oxohalogen salt, and
 wherein fuel of the firing agent is a polymer binder, powdered fine crystalline carbon, or a nitrogen-containing compound.   
   
   
       15 . The firing agent according to  claim 12 , further comprising a plasticizer, an aging stabilizer, or a slag forming agent. 
   
   
       16 . The firing agent according to  claim 12 , wherein the weight ratio between the oxidizing agent of the firing agent and the fuel of the firing agent is 68:32 to 98:2. 
   
   
       17 . The firing agent according to  claim 1 , wherein the occupant protection device is an airbag device, and the firing agent and the non-azide gas generating agent are disposed in a compartment of the vehicle. 
   
   
       18 . The firing agent according to  claim 1 , wherein the occupant protection device is a vehicle seat belt pretensioner, and the firing agent and the non-azide gas generating agent are disposed in a compartment of the vehicle. 
   
   
       19 . A method for using a firing agent for firing a non-azide gas generating agent, comprising the steps of:
 filling the gas generating device of the vehicle occupant protection device with the non-azide gas generating agent and the firing agent, wherein the non-azide gas generating agent burns at a first combustion speed, and the firing agent contains fuel and an oxidizing agent and burns at a second combustion speed higher than the first combustion speed.   
   
   
       20 . The method according to  claim 19 , comprising the step of filling the gas generating device with 60 to 98 mass % of the non-azide gas generating agent and 2 to 40 mass % of the firing agent. 
   
   
       21 . The method according to  claim 19 , wherein the non-azide gas generating agent has the reaching time of 25 to 100 milliseconds when charged into a closed chamber at a charging density of 0.059 g/ml and then ignited, and
 wherein the firing agent has the reaching time of 5 to 20 milliseconds when charged into a closed chamber at a charging density of 0.059 g/ml and then ignited.   
   
   
       22 . The method according to  claim 19 , wherein the non-azide gas generating agent has an oxygen balance of substantially ±0, and the firing agent has a positive oxygen balance. 
   
   
       23 . A gas generating device of vehicle occupant protection device, comprising:
 a combustion chamber;   an igniting device for supplying thermal energy to the combustion chamber;   a non-azide gas generating agent accommodated in the combustion chamber; and   a firing agent accommodated in the combustion chamber, for firing the non-azide gas generating agent,   wherein the non-azide gas generating agent burns at a first combustion speed, and   wherein the firing agent contains fuel and an oxidizing agent, and burns at a second combustion speed higher than the first combustion speed of the non-azide gas generating agent.   
   
   
       24 . The gas generating agent according to  claim 23 , wherein the non-azide gas generating agent has a shape defined by first plural dimensions including first minimum dimensions; wherein the firing agent contains an oxidizing agent and fuel and has a shape defined by second plural dimensions including second minimum dimensions; and wherein the second minimum dimensions is smaller than the first minimum dimensions of the non-azide gas generating agent.