Patent Application
20250145104
The present invention relates to a gas generator and a method for producing a gas generator.
Typically, a gas generator is widely used in which an igniter and a gas generating agent are disposed in a housing, the gas generating agent is combusted by activating the igniter, and the combustion gas is discharged to the outside from a plurality of gas discharge ports formed in the housing.
The gas generator is configured in a manner that the inside of the housing is maintained airtight before actuation by closing the plurality of gas discharge ports with a closing member such as a seal tape, and after actuation, the closing member is ruptured by a pressure of the combustion gas to open the gas discharge ports. In relation to this, there is known a technique in which a gas discharge port is formed in a manner that a protrusion (burr) is formed around the gas discharge port on an inner wall surface side of the housing and a range including the gas discharge port and the protrusion is covered with a seal tape so that the closing member is reliably ruptured in actuation of the gas generator to stabilize output performance (for example, Patent Document 1).
Patent Document 1: JP 2013-241102 A
Now, the output performance of the gas generator is defined by using a discharge amount and a discharge time of the combustion gas as parameters. In this case, to obtain stable (reproducible) output performance, it is important to ensure stable combustion of a gas generating agent.
An object of the technique of the present disclosure is to provide a gas generator having stable output performance.
To solve the above problem, the technique of the present disclosure adopts the following configuration. That is, the technique according to an embodiment of the present disclosure is a gas generator. A gas generator according to an embodiment of the present disclosure includes an igniter, a gas generating agent that generates a combustion gas by being combusted in response to actuation of the igniter, a housing accommodating the igniter and the gas generating agent inside the housing, a plurality of gas discharge ports penetrating through the housing from an inside to an outside of the housing, and a closing member attached to an inner surface of the housing, the closing member being configured to close, before the actuation of the igniter, the plurality of gas discharge ports by covering an opening of each of the plurality of gas discharge ports on an inner surface side of the housing and open the plurality of gas discharge ports by being ruptured due to reception of a pressure of the combustion gas generated by the actuation of the igniter. The plurality of gas discharge ports include at least one first gas discharge port and at least one second gas discharge port, the at least one first gas discharge port and the at least one second gas discharge port being configured such that rupturing pressures of the closing member at the at least one first gas discharge port and the at least one second gas discharge port are different from each other, a minimum flow path cross-sectional area of a gas flow path formed by the at least one first gas discharge port is equivalent to a minimum flow path cross-sectional area of a gas flow path formed by the at least one second gas discharge port, and the at least one first gas discharge port and the at least one second gas discharge port are different from each other in at least one of a shape or a peripheral length of an opening on the inner surface side of the housing.
According to the gas generator of the embodiment of the present disclosure, the minimum flow path cross-sectional areas of the first gas discharge port and the second gas discharge port that control gas discharge amounts are made equivalent to each other, which causes a gas discharge amount per unit time of the first gas discharge port and a gas discharge amount per unit time of the second gas discharge port to be equivalent to each other. Further, at least either of the shape or the peripheral length of the opening on the inner surface side of the housing is made different between the first gas discharge port and the second gas discharge port, causing the rupturing pressure at the first gas discharge port and the rupturing pressure at the second gas discharge port to be different from each other. In other words, it is possible to intentionally set two types of gas discharge ports having internal pressure control functions for the housing equivalent to each other and different ease of opening. According to this configuration, an opening timing of the first gas discharge port and an opening timing of the second gas discharge port are made different from each other, and thus a rapid internal pressure drop of the housing can be suppressed when the igniter is activated. As a result, combustion performance of the gas generating agent can be maintained and output performance of the gas generator can be stabilized.
In addition, in the gas generator according to an embodiment of the present disclosure, the at least one first gas discharge port and the at least one second gas discharge port may be closed with the closing members having specifications identical to each other.
In addition, in the gas generator according to an embodiment of the present disclosure, each of the at least one first gas discharge port and the at least one second gas discharge port may be a port having a circular cross section, and the at least one first gas discharge port and the at least one second gas discharge port may be different from each other in a port diameter of the opening on the inner surface side of the housing.
Further, in the gas generator according to an embodiment of the present disclosure, each of the at least one first gas discharge port and the at least one second gas discharge port may include a straight portion having a constant cross section in a thickness direction of the housing and a tapered portion continuous with the straight portion and having a cross-sectional area increasing with distance from the straight portion in the thickness direction, in one of the at least one first gas discharge port and the at least one second gas discharge port, the tapered portion may open on the inner surface side of the housing and the straight portion may open on an outer surface side of the housing, and in the other of the at least one first gas discharge port and the at least one second gas discharge port, the straight portion may open on the inner surface side of the housing and the tapered portion may open on the outer surface side of the housing.
Further, in the gas generator according to an embodiment of the present disclosure, the straight portion may be constituted by a shear surface, and the tapered portion may be constituted by a fracture surface.
In addition, in the gas generator according to an embodiment of the present disclosure, a relationship of 0.3<t2/t1<0.7 may be satisfied where a thickness of the housing is denoted by t1 and a length of the straight portion in the thickness direction of the housing is denoted by t2.
Further, in the gas generator according to an embodiment of the present disclosure, a protruding portion protruding toward the inner side of the housing may be formed at least a part of a peripheral edge of an opening on the inner surface side of the housing of only one of the at least one first gas discharge port and the at least one second gas discharge port, and the closing member may be attached to the inner surface of the housing while covering the protruding portion.
In addition, in the gas generator according to an embodiment of the present disclosure, a peripheral edge of an opening on the inner surface side of the housing of only one of the at least one first gas discharge port and the at least one second gas discharge port may be chamfered.
Moreover, the technique according to an embodiment of the present disclosure can also be specified as a method for producing a gas generator. That is, the technique according to an embodiment of the present disclosure is a method for producing a gas generator including an igniter, a gas generating agent that generates a combustion gas by being combusted in response to actuation of the igniter, a housing accommodating the igniter and the gas generating agent inside the housing, a plurality of gas discharge ports penetrating through the housing from an inside to an outside of the housing, and a closing member configured to close the plurality of gas discharge ports, the method including forming the plurality of gas discharge ports including at least one first gas discharge port and at least one second gas discharge port in the housing in such a manner that rupturing pressures of the closing member at the at least one first gas discharge port and the at least one second gas discharge port are different from each other, and attaching the closing member to an inner surface of the housing in such a manner that the closing member covers an opening of each of the plurality of gas discharge ports on the inner surface side of the housing. In the forming the plurality of gas discharge ports in the housing, a minimum flow path cross-sectional area of a gas flow path formed by the at least one first gas discharge port and a minimum flow path cross-sectional area of a gas flow path formed by the at least one second gas discharge port are equivalent to each other, and the at least one first gas discharge port and the at least one second gas discharge port are different from each other in at least one of a shape or a peripheral length of an opening on the inner surface side of the housing.
Further, in the method for producing a gas generator according to an embodiment of the present disclosure, in the forming the plurality of gas discharge ports in the housing, one of the at least one first gas discharge port and the at least one second gas discharge port may be formed by punching a hole from an outer surface side of the housing, and the other of the at least one first gas discharge port and the at least one second gas discharge port may be formed by punching a hole from the inner surface side of the housing.
In addition, in the method for producing a gas generator according to an embodiment of the present disclosure, in the forming the plurality of gas discharge ports in the housing, chamfering may be performed on an opening on the inner surface side of the housing of only one of the at least one first gas discharge port and the at least one second gas discharge port.
Further, in the method for producing a gas generator according to the present disclosure, in the attaching the closing member to the inner surface of the housing, the at least one first gas discharge port and the at least one second gas discharge port may be closed with the closing members having specifications identical to each other.
According to the technique of the present disclosure, a gas generator with stable output performance can be provided.
A gas generator according to an embodiment of the present disclosure will be described below with reference to the drawings. In the following embodiment, an aspect where a technique according to an embodiment of the present disclosure is applied to a gas generator for an airbag (inflater) will be described. However, the application of the technique according to the present disclosure is not limited thereto. For example, the technique may be applied to a gas generator for a seat belt retractor. The configurations, combinations thereof, and the like in each embodiment are an example, and various additions, omissions, substitutions, and other changes may be made as appropriate without departing from the spirit of the present invention. The present disclosure is not limited by the embodiments, but only limited by the claims.
Hereinafter, Embodiment 1 will be described. Embodiment 1 corresponds to an aspect in which the peripheral length of the opening of the first gas discharge port on the inner surface side of the housing and the peripheral length of the opening of the second gas discharge port on the inner surface side of the housing are different from each other among aspects to which the technique according to the present disclosure can be adopted.
As illustrated in
An upper shell 2 and a lower shell 3 each made of a metal and formed into a bottomed substantially cylindrical shape are joined in a state where respective open ends face each other. Thus, the housing 1 is formed in a short cylindrical shape including a tubular peripheral wall portion denoted by a reference sign 11 and in which both ends of the peripheral wall portion 11 in an axial direction are closed. The center axis CA1 in
The upper shell 2 includes an upper peripheral wall portion 21 having a tubular shape and a top plate portion 22 that closes an upper end of the upper peripheral wall portion 21. A joining portion 23 extending radially outward is connected to a lower end portion of the upper peripheral wall portion 21. The lower shell 3 includes a lower peripheral wall portion 31 having a tubular shape and a bottom plate portion 32 that closes a lower end of the lower peripheral wall portion 31. A joining portion 33 extending radially outward is connected to an upper end portion of the lower peripheral wall portion 31. A first attachment hole 32a for attaching the first ignition device 4 to the bottom plate portion 32 and a second attachment hole 32b for attaching the second ignition device 7 to the bottom plate portion 32 are formed in the bottom plate portion 32.
The joining portion 23 of the upper shell 2 and the joining portion 33 of the lower shell 3 are overlapped and joined by laser welding or the like to form the housing 1 having a short cylindrical shape with both axial ends closed. The upper peripheral wall portion 21 of the upper shell 2 and the lower peripheral wall portion 31 of the lower shell 3 form the peripheral wall portion 11 that is tubular and connects the top plate portion 22 and the bottom plate portion 32. That is, the housing 1 includes the peripheral wall portion 11 that is tubular, the top plate portion 22 provided at one end of the peripheral wall portion 11, and the bottom plate portion 32 provided at the other end and facing the top plate portion 22. The peripheral wall portion 11, the top plate portion 22, the bottom plate portion 32, and the second inner tube member 8, which will be described below, define a first combustion chamber 10. The first ignition device 4, the first inner tube member 5, the transfer charge 6, the filter 9, and the first gas generating agent 110 are disposed in the first combustion chamber 10.
As illustrated in
The first inner tube member 5 is a bottomed tubular member extending from the bottom plate portion 32 toward the top plate portion 22 and includes a surrounding wall portion 51 having a tubular shape and a lid wall portion 52 that closes one end portion of the surrounding wall portion 51. The first ignition device 4 is fitted or press-fitted to the other end portion of the surrounding wall portion 51, and thus the first inner tube member 5 is attached to the bottom plate portion 32. As illustrated in
The second inner tube member 8 is a bottomed tubular member extending from the bottom plate portion 32 toward the top plate portion 22 and includes a surrounding wall portion 81 having a tubular shape and a lid wall portion 82 that closes one end portion of the surrounding wall portion 81. The second ignition device 7 is fitted or press-fitted to the other end portion of the surrounding wall portion 81, and thus the second inner tube member 8 is attached to the bottom plate portion 32. As illustrated in
As illustrated in
In addition to a known black powder, a gas generating agent having good ignition properties and a higher combustion temperature than that of the first gas generating agent 110 can be used as the transfer charge 6. A combustion temperature of the transfer charge 6 can be set within a range from 1700 to 3000° C. As the transfer charge 6, a known transfer charge containing, for example, nitroguanidine (34 wt. %) and strontium nitrate (56 wt. %) can be used. In addition, the transfer charge 6 may have various shapes, such as a granular shape, a pellet shape, a columnar shape, or a disk shape.
The first gas generating agent 110 is combusted by the actuation of the first igniter 41 to generate the combustion gas. The second gas generating agent 120 is combusted by the actuation of the second igniter 71 to generate the combustion gas. As the first gas generating agent 110 and the second gas generating agent 120, a gas generating agent having a relatively low combustion temperature can be used. The combustion temperature of each of the first gas generating agent 110 and the second gas generating agent 120 can be set within the range from 1000 to 1700° C. As the first gas generating agent 110 and the second gas generating agent 120, a known gas generating agent containing, for example, guanidine nitrate (41 wt. %), basic copper nitrate (49 wt. %), a binder, and an additive can be used. The first gas generating agent 110 and the second gas generating agent 120 may also have a variety of shapes, such as a granular shape, a pellet shape, a columnar shape, or a disk shape.
As illustrated in
Here, in the present specification, an area of a cross section orthogonal to a flow direction of the combustion gas, of the gas flow path formed by the gas discharge port H1, is defined as a flow path cross-sectional area. In Embodiment 1, a direction in which the gas discharge port H1 penetrates through the housing 1, that is, the thickness direction of the housing 1 is the flow direction of the combustion gas. Then, the minimum cross-sectional area of the gas flow path is defined as a minimum flow path cross-sectional area. In the gas discharge port H1, a portion having the minimum flow path cross-sectional area is a rate-regulating portion (choke) of gas discharge. That is, a gas discharge amount per unit time of the gas discharge port H1 is determined according to the minimum flow path cross-sectional area. Then, an internal pressure of the housing 1 can be controlled by adjusting the number of gas discharge ports to be opened and an amount of gas to be discharged from the gas discharge ports per unit time.
As illustrated in
As illustrated in
As illustrated in
As illustrated in
When the first igniter 41 is activated, the seal tape S1 is pressurized by the generated gas to be ruptured, thereby opening the plurality of gas discharge ports H1. Here, in the present specification, a pressure required for opening each gas discharge port by rupturing the closing member (the seal tape S1 in the present example) at the gas discharge port is defined as a “rupturing pressure”. When the closing member is ruptured, the closing member having received the pressure of the combustion gas is pressed against a peripheral edge of the opening of the gas discharge port on the inner surface side of the housing, and sheared along the peripheral edge. Thus, the rupturing pressure of the closing member at each gas discharge port is determined according to specifications of the closing member and features of the opening of the gas discharge port. The specifications of the closing member are specifically a tensile strength and a thickness of the closing member. The lower the tensile strength of the closing member is or the thinner the thickness of the closing member is, the lower the rupturing pressure is. Further, the features of the opening of the gas discharge port are specifically a shape or a peripheral length (length of the peripheral edge) of the opening of the gas discharge port on the inner surface side of the housing. The shape of the opening includes a projection or a chamfered portion formed on the peripheral edge of the opening in addition to a planar shape exhibited by the peripheral edge of the opening. When the projection is formed on the peripheral edge of the opening, the rupturing pressure becomes low, and when the peripheral edge of the opening is chamfered, the rupturing pressure becomes high. Also, the longer the peripheral length of the opening, the lower the rupturing pressure.
In the gas generator 100 according to Embodiment 1, a rupturing pressure of the seal tape S1 at the large port 12 is set to be lower than a rupturing pressure of the seal tape S1 at the small port 13. In setting the rupturing pressures at the large port 12 and the small port 13, for example, a peripheral length of the opening of the large port 12 on the inner surface 11a side of the housing 1 may be longer than a peripheral length of the opening of the small port 13 on the inner surface 11a side, or the seal tape S1 closing the large port 12 may be thinner than the seal tape S1 closing the small port 13.
As illustrated in
In the gas generator 100 according to Embodiment 1, a gas discharge amount per unit time of the first small port 13a and a gas discharge amount per unit time of the second small port 13b are made equivalent to each other, but a rupturing pressure of the seal tape S1 at the first small port 13a and a rupturing pressure of the seal tape S1 at the second small port 13b are made slightly different from each other. As will be described in detail later, in the gas generator 100 according to Embodiment 1, the features of the opening of the small port 13 on the inner surface 11a side are set in a manner that the rupturing pressure of the seal tape S1 at the first small port 13a is lower than the rupturing pressure of the seal tape S1 at the second small port 13b. However, this does not limit the magnitude relationship between the rupturing pressure at the first gas discharge port (first small port) and the rupturing pressure at the second gas discharge port (second small port) in the technique according to the embodiment of the present disclosure. In addition, in the technique according to the embodiment of the present disclosure, it is not essential that both of the number of first gas discharge ports and the number of second gas discharge ports are plural, and it is sufficient that the plurality of gas discharge ports include at least one first gas discharge port and at least one second gas discharge port that are configured such that rupturing pressures of the closing member thereat are different from each other. In addition, the arrangement of the first gas discharge ports and the second gas discharge ports in the technique according to the embodiment of the present disclosure is not limited to the above. For example, a plurality of first gas discharge ports or a plurality of second gas discharge ports may be unevenly distributed.
As illustrated in
As illustrated in
Similarly to the first small port 13a, the second small port 13b includes the straight portion 131 constituted by a shear surface and the tapered portion 132 constituted by a fracture surface. A diameter of the straight portion 131 of the second small port 13b is equivalent to a diameter of the straight portion 131 of the first small port 13a. In the second small port 13b according to Embodiment 1, contrary to the first small port 13a, the straight portion 131 opens on the inner surface 11a side of the housing 1, and the tapered portion 132 opens on the outer surface 11b side of the housing 1. The straight portion 131 of the second small port 13b opens at the inner surface 11a to form the opening 13b1. The tapered portion 132 of the second small port 13b opens at the outer surface 11b to form the opening 13b2. Although details will be described later, the second small port 13b according to Embodiment 1 is formed by punching a hole from the inner surface 11a side of the housing 1, contrary to the first small port 13a.
As illustrated in
Here, the minimum flow path cross-sectional area and the features of the opening on the inner surface 11a side of the housing 1 will be compared between the first small port 13a and the second small port 13b. As described above, the first small port 13a and the second small port 13b have the smallest flow path cross-sectional areas in the straight portions 131 having the same diameter as each other. Therefore, the minimum flow path cross-sectional area A1 of the first small port 13a is equivalent to the minimum flow path cross-sectional area A2 of the second small port 13b. That is, a relationship of A1=A2 is satisfied. Thus, the first small port 13a and the second small port 13b have the gas discharge amounts per unit time that are equivalent to each other. Further, as illustrated in
Next, the method for producing the gas generator according to the first embodiment will be described. Note that the method for producing the gas generator according to the embodiment of the present disclosure is not limited to the following method.
First, in the step S101 of preparing, the first ignition device 4, the first inner tube member 5, the transfer charge 6, the second ignition device 7, the second inner tube member 8, the filter 9, the upper shell 2, the lower shell 3, the first gas generating agent 110, the second gas generating agent 120, and the seal tapes S1 are prepared.
Next, in the step S102 of forming the gas discharge ports, the plurality of gas discharge ports H1 are formed in the housing 1 in a manner that rupturing pressures of the seal tape S1 at the first small port 13a and the second small port 13b are different from each other. Specifically, the plurality of large ports 12 and the plurality of small ports 13 are formed by punching holes at the upper peripheral wall portion 21 of the upper shell 2. In the punching of the large ports 12, a punch having a diameter larger than that of a punch that is used in the punching of the small ports 13 is used. Thus, the minimum flow path cross-sectional area of the large port 12 becomes larger than the minimum flow path cross-sectional area of the small port 13. As a result, the large port 12 discharges a larger amount of gas per unit time than that of the small port 13.
Further, in the forming of the plurality of small ports 13, the punching is performed in a manner that the rupturing pressure of the seal tape S1 at the first small port 13a is different from the rupturing pressure of the seal tape S1 at the second small port 13b.
In the forming of the gas discharge ports, since the punches 200 having the same diameter are used for the first small port 13a and the second small port 13b, the straight portions 131 having the same diameter are individually formed in the first small port 13a and the second small port 13b. Therefore, the minimum flow path cross-sectional area A1 in the first small port 13a and the minimum flow path cross-sectional area A2 in the second small port 13b are equivalent to each other. Further, in the forming of the gas discharge ports, by making the punching directions of the first small port 13a and the second small port 13b opposite to each other, the positional relationship of the straight portion 131 and the tapered portion 132 becomes opposite between the first small port 13a and the second small port 13b. Thus, the peripheral lengths of the opening 13a1 of the first small port 13a and the opening 13b1 of the second small port 13b are different from each other. In the present example, the peripheral length P1 of the opening 13a1 of the first small port 13a is longer than the peripheral length P2 of the opening 13b1 of the second small port 13b.
Next, in the step S103 of attaching the closing member, the seal tapes S1 are attached to the inner surface 11a of the housing 1 and thus cover the openings of the plurality of gas discharge ports H1 on the inner surface 11a side of the housing 1. Thus, all of the plurality of gas discharge ports H1 are closed. In the present example, all the large ports 12 are collectively closed with one seal tape S1, and all the small ports 13 are collectively closed with another seal tape S1. Therefore, the first small port 13a and the second small port 13b are closed with the seal tape S1 having the same specification.
Next, in the step S104 of assembling, the first ignition device 4 and the second ignition device 7 are attached to the lower shell 3, the first inner tube member 5 filled with the transfer charge 6 is fixed to the first ignition device 4, and the second inner tube member 8 filled with the second gas generating agent 120 is fixed to the second ignition device 7. Thereafter, the filter 9 is disposed at the lower shell 3, and the inside of the filter 9 is filled with the first gas generating agent 110. Finally, the upper shell 2 is put over the lower shell 3, and then, the joining portion 23 of the upper shell 2 and the joining portion 33 of the lower shell 3 are overlapped and joined by laser welding or the like to form the housing 1. As described above, the gas generator 100 is assembled.
A basic operation of the gas generator 100 according to the first embodiment will be described below with reference to
When a sensor (not illustrated) senses an impact, an ignition current is supplied to the first igniter 41 of the first ignition device 4 and the first igniter 41 is activated. Then, the ignition charge accommodated in the first igniter 41 is combusted, and a flame, a high-temperature gas, and the like, which are combustion products of the ignition charge, are discharged to the inside of the transfer charge chamber 53. Thus, the transfer charge 6 accommodated in the transfer charge chamber 53 is combusted, and a combustion gas is generated in the transfer charge chamber 53. When the seal tape closing the communication holes hl of the surrounding wall portion 51 of the first inner tube member 5 is ruptured due to the pressure of the combustion gas of the transfer charge 6, the combustion gas is discharged to the outside of the transfer charge chamber 53 through the communication holes h1. Then, the combustion gas of the transfer charge 6 comes into contact with the first gas generating agent 110 disposed around the surrounding wall portion 51, and the first gas generating agent 110 is ignited. When the first gas generating agent 110 is combusted, a high-temperature and high-pressure combustion gas is generated in the first combustion chamber 10. The seal tapes S1 are ruptured by the pressure of the combustion gas to open the plurality of gas discharge ports H1. When this combustion gas passes through the filter 9, the combustion gas is cooled, and a combustion residue is filtered. The combustion gas of the first gas generating agent 110 cooled and filtered by the filter 9 is discharged through the plurality of gas discharge ports H1 to the outside of the housing 1.
Subsequently, when the second igniter 71 of the second ignition device 7 is activated, the second gas generating agent 120 accommodated in the second combustion chamber 20 is combusted, and a combustion gas is generated in the second combustion chamber 20. When the seal tape closing the communication holes h2 of the surrounding wall portion 81 of the second inner tube member 8 is ruptured by the pressure of the combustion gas of the second gas generating agent 120, the combustion gas is discharged to the first combustion chamber 10 through the communication holes h2. After being cooled and filtered by the filter 9, the combustion gas of the second gas generating agent 120 is discharged through the plurality of gas discharge ports H1 to the outside of the housing 1.
The combustion gases of the first gas generating agent 110 and the second gas generating agent 120 flow into an airbag (not illustrated) after being discharged to the outside of the housing 1. This causes the airbag to inflate, forming a cushion between an occupant and a rigid structure and protecting the occupant from an impact.
Now, in general, combustion performance of a gas generating agent tends to improve as a temperature or pressure around the gas generating agent increases. That is, a low-temperature and low-pressure environment causes inactive combustion of the gas generating agent. Thus, for example, it is necessary to maintain the internal pressure of the housing during the low-temperature activation, particularly at the initial stage where the gas generating agent starts to be combusted, and thus a difference in output performance of the gas generator between the activation at a high temperature (high-temperature activation) and the activation at a low temperature (low-temperature activation) can be reduced and the output performance can be stabilized.
As described above, in the gas generator 100 according to Embodiment 1, the rupturing pressure of the seal tape S1 at the large port 12 is set to be lower than the rupturing pressure of the seal tape S1 at the small port 13. For example, it is assumed that the first igniter 41 and the second igniter 71 are activated at the same time at the time of low-temperature activation and all of the first gas generating agent 110 and the second gas generating agent 120 are combusted. In this case, at the initial stage, only the large ports 12 among the plurality of gas discharge ports H1 open as the internal pressure of the housing 1 increases. As a result of this, a part of the combustion gas is discharged, and thus, the internal pressure of the housing 1 lowers. However, since the small ports 13 are closed, the combustion performance of the gas generating agent is maintained. When the internal pressure of the housing 1 further increases along with the combustion of the gas generating agent, the small ports 13 open with a delay from the opening of the large ports 12. However, if all the small ports 13 (all the first small ports 13a and all the second small ports 13b) open at the same time, there is a concern that the internal pressure of the housing 1 rapidly drops and the combustion performance of the gas generating agent deteriorates. On the other hand, in the gas generator 100 according to Embodiment 1, the ease of opening is made different between the first small port 13a and the second small port 13b by making the rupturing pressure of the seal tape S1 slightly different between the first small port 13a and the second small port 13b. Therefore, the first small ports 13a at which rupturing pressure is relatively low open relatively early, and the second small ports 13b at which rupturing pressure is relatively high open relatively late. The open timings are made different between the first small port 13a and the second small port 13b, and thus all the small ports 13 do not open at the same time so that a sudden drop in internal pressure of the housing 1 is suppressed, and the combustion performance of the gas generating agent is maintained.
As described above, the gas generator 100 according to Embodiment 1 includes the housing 1 accommodating the first igniter 41 and the first gas generating agent 110 therein, the plurality of gas discharge ports H1 penetrating through the housing 1 from the inside to the outside of the housing 1, and the seal tape S1 attached to the inner surface 11a of the housing 1. The seal tape S1 covers the openings of the plurality of gas discharge ports H1 on the inner surface 11a side of the housing 1 before actuation of the gas generator 100 to close the plurality of gas discharge ports H1, and is ruptured by the pressure of the combustion gas generated in the housing 1 by the actuation of the gas generator 100 to open the plurality of gas discharge ports H1. The plurality of gas discharge ports H1 include at least one first small port 13a and at least one second small port 13b that are configured such that rupturing pressures of the seal tape S1 thereat are different from each other. The minimum flow path cross-sectional area A1 of the gas flow path formed by the first small port 13a is equivalent to the minimum flow path cross-sectional area A2 of the gas flow path formed by the second small port 13b, and the first small port 13a and the second small port 13b have different peripheral lengths of the openings on the inner surface 11a side of the housing 1 from each other, differentiating the rupturing pressures from each other.
According to the gas generator 100 configured as described above, by making the minimum flow path cross-sectional area for controlling the gas discharge amount equivalent between the first small port 13a and the second small port 13b, the gas discharge amount per unit time of the first small port 13a and the gas discharge amount per unit time of the second small port 13b can be made equivalent to each other. Furthermore, by making the peripheral length of the opening on the inner surface 11a side of the housing 1 different between the first small port 13a and the second small port 13b, the rupturing pressures at the first small port 13a and the second small port 13b can be made different from each other. That is, it is possible to intentionally set two types of gas discharge ports having equivalent internal pressure control functions for the housing 1 and different ease of opening. According to this configuration, the open timings of the first small port 13a and the second small port 13b are made different from each other, and thus, a rapid internal pressure drop of the housing 1 can be suppressed at the initial stage of activation of the gas generator 100. As a result, the combustion performance of the gas generating agent can be maintained and the output performance of the gas generator 100 can be stabilized.
Further, in the gas generator 100 according to Embodiment 1, the first small ports 13a and the second small ports 13b are closed with the seal tape S1 having the same specification. That is, a difference between the rupturing pressures is generated not by a difference in specification of the seal tape S1 but by a difference between the features (peripheral lengths) of the opening 13a1 of the first small port 13a and the opening 13b1 of the second small port 13b. According to this, since it is not necessary to make the specification of the seal tape S1 different between the first small port 13a and the second small port 13b, all the small ports 13 can be covered with a common (one) seal tape S1. However, in the technique according to the embodiment of the present disclosure, the specification of the closing member may be different between the first gas discharge port and the second gas discharge port.
Note that although the gas generator 100 according to Embodiment 1 is configured such that the rupturing pressure at the first small port 13a is lower than the rupturing pressure at the second small port 13b, the magnitude relationship between the rupturing pressure at the first gas discharge port and the rupturing pressure at the second gas discharge port in the technique according to the embodiment of the present disclosure is not limited to the above. The rupturing pressure at the first gas discharge port may be higher than the rupturing pressure at the second gas discharge port. In addition, in the gas generator 100 according to Embodiment 1, the large port 12 and the small port 13 having different minimum flow path cross-sectional areas are included in the plurality of gas discharge ports H1. However, in the technology according to the embodiment of the present disclosure, it is not essential that a plurality of types of gas discharge ports having different minimum flow path cross-sectional areas are provided.
In the technique according to the embodiment of the present disclosure, the plurality of gas discharge ports may include, in addition to the first gas discharge port and the second gas discharge port, a gas discharge port that has a minimum flow path cross-sectional area equivalent to those of the first gas discharge port and the second gas discharge port and is configured such that a rupturing pressure of the closing member is different from those at the first gas discharge port and the second gas discharge port. That is, three or more types of gas discharge ports that have minimum flow path cross-sectional areas equivalent to one another and are configured such that rupturing pressures of the closing member thereat are different from one another may be provided.
In the gas generator 100 according to Embodiment 1, each of the first small port 13a and the second small port 13b is formed as a port having a circular cross section, and the first small port 13a and the second small port 13b have the port diameters (D1, D2) of the openings (13a1, 13b1), on the inner surface 11a side of the housing 1, different from each other. This can make the peripheral length (P1, P2) of the opening on the inner surface 11a side of the housing 1 different between the first small port 13a and the second small port 13b. Note that each of the cross-sectional shapes of the first gas discharge port and the second gas discharge port, and the shapes of the openings of the first gas discharge port and the second gas discharge port is not limited to a circular shape, and various shapes such as an elliptical shape, an oval shape, and a polygonal shape can be adopted in the technique according to the embodiment of the present disclosure.
Further, each of the first small port 13a and the second small port 13b according to Embodiment 1 includes the straight portion 131 having a constant cross-section in the thickness direction of the housing 1 and the tapered portion 132 continuous with the straight portion 131 and having a cross-sectional area that increases with distance from the straight portion 131 in the thickness direction. In either (the first small port 13a) of the first small port 13a or the second small port 13b, the tapered portion 132 opens on the inner surface 11a side of the housing 1, and the straight portion 131 opens on the outer surface 11b side of the housing 1. Further, in the other (the second small port 13b), the straight portion 131 opens on the inner surface 11a side of the housing 1, and the tapered portion 132 opens on the outer surface 11b side of the housing 1. By making the positional relationship of the straight portion 131 and the tapered portion 132 opposite between the first small port 13a and the second small port 13b as described above, the minimum flow path cross-sectional areas of the first small port 13a and the second small port 13b are equivalent to each other, but the rupturing pressures thereat of the seal tape S1 can be made different from each other. Note that in the technique according to the embodiment of the present disclosure, the second gas discharge port (the second small port 13b) may include a tapered portion opening on the inner surface side of the housing and a straight portion opening on the outer surface side of the housing, and the first gas discharge port (the first small port 13a) may include a straight portion opening on the inner surface side of the housing and a tapered portion opening on the outer surface side of the housing.
In addition, in the gas generator 100 according to Embodiment 1, the straight portion 131 is constituted by a shear surface, and the tapered portion 132 is constituted by a fracture surface. The gas discharge port H1 including the straight portion 131 and the tapered portion 132, as described above, can be suitably formed by punching. However, in the technique according to the embodiment of the present disclosure, the method of forming the first gas discharge port and the second gas discharge port in the housing is not limited to the punching. For example, the first gas discharge port and the second gas discharge port may be formed by drilling holes.
As illustrated in
Furthermore, the method for producing the gas generator 100 according to Embodiment 1 includes forming the plurality of gas discharge ports H1 including at least one first small port 13a and at least one second small port 13b in the housing 1, and attaching the seal tape S1 to the inner surface 11a of the housing 1 and thus covering the openings of the plurality of gas discharge ports H1 on the inner surface 11a side of the housing 1. In the forming of the plurality of gas discharge ports H1 in the housing 1, the minimum flow path cross-sectional area A1 of the gas flow path formed by the first small port 13a and the minimum flow path cross-sectional area A2 of the gas flow path formed by the second small port 13b are made equivalent to each other, and the first small port 13a and the second small port 13b have the peripheral lengths of the openings, on the inner surface 11a side of the housing 1, different from each other. As described above, in the method for producing the gas generator 100, the plurality of gas discharge ports H1 are formed in the housing 1 in a manner that the rupturing pressure of the seal tape S1 is different between the first small port 13a and the second small port 13b. According to such a production method, the open timings of the first small port 13a and the second small port 13b are made different from each other, and a rapid internal pressure drop of the housing 1 can be suppressed. That is, the gas generator 100 having stable output performance can be produced.
Further, in the method for producing the gas generator 100 according to Embodiment 1, in the forming of the plurality of gas discharge ports H1 in the housing 1, the first small port 13a is formed by punching a hole from the outer surface 11b side of the housing 1, and the second small port 13b is formed by punching a hole from the inner surface 11a side of the housing 1. That is, the punching directions of the first small port 13a and the second small port 13b are opposite to each other. Thus, the first small port 13a and the second small port 13b can have the peripheral lengths of the openings, on the inner surface 11a side of the housing 1, different from each other. Note that such a difference in peripheral length between the openings of the gas discharge ports on the inner surface 11a side of the housing 1 may be applied to the large ports 12 other than the first small port 13a and the second small port 13b.
A gas generator 100 according to each of modified examples of Embodiment 1 will be described below. In the description of the modified examples, differences from the aspects described in
The second small port 13b according to Modified Example 1 is formed as a port having a circular cross section. The second small port 13b according to Modified Example 1 is different from the second small port 13b illustrated in
In Modified Example 1, the first small port 13a illustrated in
As illustrated in
In Modified Example 2, the minimum flow path cross-sectional area A1 of the first small port 13a is equivalent to the minimum flow path cross-sectional area A2 of the second small port 13b. Therefore, the diameter D1 of the opening 13a1 of the first small port 13a on the inner surface 11a side is larger than the diameter D2 of the opening 13b1 of the second small port 13b on the inner surface 11a side. As a result, since the peripheral length P1 of the opening 13a1 of the first small port 13a is longer than the peripheral length P2 of the opening 13b1 of the second small port 13b, a rupturing pressure at the first small port 13a can be made lower than a rupturing pressure at the second small port 13b. As described above, also in the gas generator 100 according to Modified Example 2, the minimum flow path cross-sectional areas of the first small port 13a and the second small port 13b are equivalent to each other and the rupturing pressures thereat of the closing member are different from each other. Further, the aspects of
The gas generator 100 according to Embodiment 2 will be described below. Embodiment 2 corresponds to an aspect in which a shape of the opening of the first gas discharge port on the inner surface side of the housing and a shape of the opening of the second gas discharge port on the inner surface side of the housing are different from each other among aspects that can be adopted by the technique according to the present disclosure. In the description of Embodiment 2, differences from the aspects according to the Embodiment 1 described in
As illustrated in
As illustrated in
As described above, in the gas generator 100 according to Embodiment 2, in the forming of the plurality of gas discharge ports H1 in the housing 1, the shape of the opening on the inner surface 11a side of the housing 1 is made different between the first small port 13a and the second small port 13b. Therefore, also in the gas generator 100 according to Embodiment 2, the minimum flow path cross-sectional areas of the first small port 13a and the second small port 13b are equivalent to each other, and the rupturing pressures thereat of the seal tape S1 are different from each other. As a result, the output performance of the gas generator 100 can be stabilized.
Note that in Embodiment 2, the protruding portion 133 is formed at the first small port 13a and the chamfered portion 134 is formed at the second small port 13b, but the technique according to the embodiment of the present disclosure is not limited thereto. By forming the protruding portion on at least a part of the peripheral edge of the opening, on the inner surface side of the housing, of only either of the first gas discharge port (first small port 13a) or the second gas discharge port (second small port 13b), the rupturing pressures at the first gas discharge port and the second gas discharge port can be made different from each other. For example, either of the first gas discharge port or the second gas discharge port may be formed by punching or drilling a hole from the outer surface side of the housing, and the other may be formed by punching a hole from the inner surface side of the housing, thereby forming the protruding portion at least a part of the opening, on the inner surface side of the housing, of only the either of the first gas discharge port or the second gas discharge port. In addition, by chamfering the peripheral edge of the opening, on the inner surface side of the housing, of only either of the first gas discharge port or the second gas discharge port, the rupturing pressures at the first gas discharge port and the second gas discharge port can be made different from each other. Further, the shapes illustrated in
In Embodiment 2, the planar shape of the peripheral edge of the opening on the inner surface 11a side of the housing 1 may be different between the first small port 13a and the second small port 13b.
For example, the opening 13a1 of the first small port 13a and the opening 13b1 of the second small port 13b may have different shapes selected from
Suitable embodiments according to the present disclosure have been described above, but each embodiment disclosed in the present specification can be combined with each of features disclosed in the present specification. Note that in Embodiment 1, the aspect has been described in which the first gas discharge port and the second gas discharge port are different from each other in a peripheral length of the opening on the inner surface side of the housing from each other, and in Embodiment 2, the aspect has been described in which these openings have different shapes from each other. However, both of the shape and the peripheral length of the opening may be different between the first gas discharge port and the second gas discharge port. That is, in the technique according to the present disclosure, at least one of the shape or the peripheral length of the opening on the inner surface side of the housing may be different between the first gas discharge port and the second gas discharge port. Note that even when a plurality of gas discharge ports having different shapes or peripheral lengths of the openings on the inner surface side of the housing are provided, a case where a difference in shape or peripheral length is recognized to be within processing tolerance of the gas discharge ports is excluded from the technique according to the present disclosure. In addition, in the above-described embodiments, a so-called dual type gas generator including two igniters has been exemplified, but even in a case where the technique according to the present disclosure is adopted to a so-called single type gas generator including only one igniter as illustrated in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-103652 | Jun 2022 | JP | national |
The present application is a Continuation of International Patent Application No. PCT/JP2023/003071 filed on Jan. 31, 2023, which contains subject matter related to Japanese Patent Application No. 2022-103652 filed in the Japan Patent Office on Jun. 28, 2022, the entire contents of each are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2023/003071 | Jan 2023 | WO |
| Child | 19002769 | US |
