Manufacturing method, and curtain airbags

Abstract

To reduce sewing time during the manufacturing of curtain airbags. [Solution] The curtain airbag comprises at least one main inflation chamber that inflates and deploys when inflation gas is supplied, and at least one secondary inflation chamber connected to the main inflation chamber that inflates and deploys after the main inflation chamber has begun to inflate. The method for manufacturing this curtain airbag includes a first step of sewing together the portion that partitions the main inflation chamber with a first sewing pitch while at least two airbag base fabrics are stacked on top of each other, and a second step of sewing together the portion that partitions the secondary inflation chamber with a second sewing pitch which is a larger sewing pitch than the first sewing pitch while at least two airbag base fabrics are stacked on top of each other.

Description

【Technical Field】 【0001】 The present disclosure relates to a manufacturing method and a curtain airbag. 【Background Art】 【0002】 Patent Document 1 describes that a curtain airbag is deployed along the side of a vehicle to protect the heads of the front-seat and rear-seat passengers of the vehicle. The curtain airbag of Patent Document 1 is manufactured by integrally weaving a bag by a one-piece weaving method. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2023-71556 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 The manufacturing method of a curtain airbag is not limited to the method of integrally weaving a bag by a one-piece weaving method as described in Patent Document 1, and there is also a method of sewing a plurality of airbag base fabrics in a stacked state. Since the curtain airbag is larger in size than other airbags provided in the vehicle, when manufacturing the curtain airbag by sewing, there is a problem that the sewing time becomes long. In order to improve production efficiency, further shortening of the sewing time during airbag manufacturing is desired. 【Means for Solving the Problems】 【0005】 The present disclosure can be realized in the following forms. 【0006】 According to one embodiment of the present disclosure, a method for manufacturing a curtain airbag is provided. The curtain airbag comprises at least one main inflation chamber that inflates and deploys when inflation gas is supplied, and at least one secondary inflation chamber connected to the main inflation chamber that inflates and deploys after the main inflation chamber has begun to inflate. The manufacturing method includes a first step of sewing a portion that partitions the main inflation chamber with a first sewing pitch while at least two airbag base fabrics are stacked on top of each other, and a second step of sewing a portion that partitions the secondary inflation chamber with a second sewing pitch which is a larger sewing pitch than the first sewing pitch while at least two airbag base fabrics are stacked on top of each other. According to the above-described manufacturing method, the portion partitioning the secondary expansion chamber is sewn with a larger stitch pitch than the portion partitioning the main expansion chamber, thereby shortening the overall sewing time. The main expansion chamber protects the occupant's head by deploying between the side wall of the vehicle on which the curtain airbag is installed and the occupant. For this reason, the main expansion chamber is required to maintain sufficient strength. On the other hand, the secondary expansion chamber is provided to mitigate the impact received by the occupant from the main expansion chamber by releasing the expansion gas from the main expansion chamber. For this reason, the expansion gas first flows into the main expansion chamber, and then a portion of the expansion gas in the main expansion chamber flows into the secondary expansion chamber. Therefore, it is assumed that the pressure on the secondary expansion chamber is lower than the pressure on the main expansion chamber. For this reason, the strength required of the secondary expansion chamber is not higher than the strength that the main expansion chamber must maintain. For this reason, even if the portion partitioning the secondary expansion chamber is sewn with a larger stitch pitch, the overall functionality of the curtain airbag will not be significantly reduced. According to the above configuration, it is possible to shorten the manufacturing time while maintaining the performance of the curtain airbag. 【0007】 In the manufacturing method of the above embodiment, the curtain airbag further comprises at least one flow path connecting the main inflation chamber and the sub-inflation chamber, the flow path comprising at least one constricted portion at the connection position between the main inflation chamber and the sub-inflation chamber, and in the second step, with the at least two airbag base fabrics stacked, the portions constituting the constricted portion may be sewn together at the first sewing pitch. According to the above configuration, in the constricted area where stress is expected to concentrate, the sewing is performed with a first sewing pitch that is smaller than the second sewing pitch, thus maintaining the strength of the airbag while shortening the overall sewing time. 【0008】 In the above-described manufacturing method, the switching between the first step and the second step may be performed at a position where the direction of the stitching changes. According to the above configuration, it is easy to identify the position where the sewing pitch changes. 【0009】 In the above-described manufacturing method, the portion to be sewn with the first sewing pitch and the portion to be sewn with the second sewing pitch may be determined based on the results of a simulation performed prior to the first and second steps to analyze the portion where stress is concentrated when the expansion gas is supplied. According to the above configuration, the sewing method is determined based on the results of an analysis of stress concentration points through simulation, and is therefore determined to use either the first sewing pitch or the second sewing pitch. This suppresses the occurrence of problems such as the curtain airbag not functioning properly due to damage to the sewing portion during curtain airbag operation. 【0010】 In the manufacturing method of the above embodiment, the difference between the first sewing pitch and the second sewing pitch may be set to 0.5 millimeters or more and 1.0 millimeter or less. According to the above configuration, a certain difference is made between the first sewing pitch and the second sewing pitch, resulting in the effect of shortening the overall sewing time. 【0011】 In another embodiment of the present disclosure, a curtain airbag having a plurality of inflation chambers is provided. In this curtain airbag, the plurality of inflation chambers are defined by at least two airbag base fabrics that are overlapped and sewn together, and the plurality of inflation chambers include at least one main inflation chamber that inflates and deploys when inflation gas is supplied, and at least one secondary inflation chamber connected to the main inflation chamber that inflates and deploys after the main inflation chamber has begun to inflate. The portion that partitions the main inflation chamber and the portion that constitutes the constriction of the flow path connecting the main inflation chamber and the secondary inflation chamber are sewn with a predetermined sewing pitch, which is a first sewing pitch, and the portion that partitions the secondary inflation chamber is sewn with a second sewing pitch that is larger than the first sewing pitch. In the above-described configuration of a curtain airbag, the main inflation chamber deploys between the side wall of the vehicle on which the curtain airbag is installed and the occupant to protect the occupant's head. Therefore, the main inflation chamber is required to maintain sufficient strength. On the other hand, the secondary inflation chamber is provided to mitigate the impact received by the occupant from the main inflation chamber by releasing the inflation gas from the main inflation chamber. Therefore, the strength required of the secondary inflation chamber is not higher than the strength that the main inflation chamber must maintain. For this reason, even if the portion partitioning the secondary inflation chamber is sewn with a large stitch pitch, the overall functionality of the curtain airbag will not be significantly reduced. According to the above configuration, it is possible to shorten the manufacturing time while maintaining the performance of the curtain airbag. [Brief explanation of the drawing] 【0012】 [Figure 1] This is an explanatory diagram showing the configuration of a curtain airbag system. [Figure 2] This is an explanatory diagram showing the internal structure of the bag. [Figure 3] This is a flowchart showing the manufacturing method for the bag body. [Modes for carrying out the invention] 【0013】 A. Embodiments: Figure 1 is an explanatory diagram showing the configuration of a curtain airbag system 100 installed in a vehicle MV. In Figure 1, the upward direction is indicated by arrow UD, the downward direction by arrow DD, the front of the vehicle MV by arrow FD, and the rear of the vehicle MV by arrow RD. The same applies to subsequent figures. The curtain airbag system 100 is stored in the ceiling along the upper part of the side window of the vehicle MV. When an impact sensor (not shown) detects that an impact has been applied to the right side of the vehicle MV, the curtain airbag system 100 deploys along the right side wall of the vehicle MV. In addition to the curtain airbag system 100, the vehicle MV also includes a curtain airbag system having a configuration substantially symmetrical to that of the curtain airbag system 100, which deploys along the left side wall when an impact is applied to the left side of the vehicle MV. 【0014】 The vehicle MV is, for example, a two-row seat automobile. The curtain airbag system 100 protects occupant PO1 sitting in the front seat of the vehicle MV and occupant PO2 sitting in the rear seat of the vehicle MV when an impact is applied to the right side of the vehicle MV. Occupants PO1 and PO2 are each restrained to their seats by seat belts of a three-point seat belt system (not shown). The curtain airbag body of the curtain airbag system 100 deploys from the ceiling of the vehicle MV along the side wall and windows of the vehicle MV when an impact is applied to the vehicle MV. Occupants PO1 and PO2 move relative to the side wall and windows of the vehicle MV due to the impact applied to the vehicle MV and their own inertia. Occupants PO1 and PO2 do not directly collide with the side wall and windows, but instead collide with the deployed airbag body. As a result, the impact applied to occupants PO1 and PO2 is mitigated. 【0015】 The curtain airbag system 100 comprises a curtain airbag body 110, an inner tube 120, and an inflator 130. Hereinafter, the curtain airbag body 110 will simply be referred to as the bag body 110. In Figure 1, the general shape of the vehicle MV, the side windows MVw1 and MVw2, and the pillar MVp1 are shown by dashed lines. 【0016】 The bag body 110 expands and deploys when the inflation gas IG is supplied from the inflator 130, reaching the state shown in FIG. 1. When the curtain airbag device 100 is not operating, the bag body 110 is stored in a folded state in a case (not shown) arranged on the ceiling of the vehicle MV. The bag body 110 is manufactured by stitching two substantially rectangular base fabrics (airbag base fabrics) made of polyethylene terephthalate in a stacked state. Note that a base fabric made of nylon 66 may also be used. In FIG. 1, the stitched portion is shown as the stitching portion 112. 【0017】 The inner tube 120 controls the flow of the inflation gas IG within the bag body 110 when supplying the inflation gas IG into the bag body 110. The inner tube 120 is arranged within the bag body 110 except for the connection opening 120a. The inner tube 120 is fixed to the bag body 110 by stitching. 【0018】 When the inflator 130 receives a signal from a control unit (not shown), it ejects the inflation gas IG for expanding the bag body 110. The inflator 130 is connected to the connection opening 120a of the inner tube 120. 【0019】 FIG. 2 is an explanatory diagram showing the internal structure of the bag body 110. The bag body 110 includes a first inflation chamber MC1, a second inflation chamber MC2, a first sub-chamber SC1, a second sub-chamber SC2, and a third sub-chamber SC3. Further, the bag body 110 includes a first flow path MO11, a second flow path MO12, a third flow path MO21, and a fourth flow path MO22. The portions into which these inflation gases are introduced are defined by the stitching portion 112. Note that in FIG. 2, no seam is shown in the portion partitioning the upper side of the fourth flow path MO22. This is because the portion partitioning the upper side of the fourth flow path MO22 is stitched together with the inner tube 120. 【0020】 The first inflation chamber MC1 is deployed to the right side of the front seat of the vehicle MV by being inflated with the inflation gas IG. The first inflation chamber MC1 mitigates the impact on the occupant PO1 sitting in the front seat of the vehicle MV. The first inflation chamber MC1 and the second inflation chamber MC2 described later are also referred to as "main inflation chambers". 【0021】 The first inflation chamber MC1 and the first sub-chamber SC1 are connected by the first flow path MO11. The first inflation chamber MC1 and the second sub-chamber SC2 are connected by the second flow path MO12. The inflation gas IG flows into the first sub-chamber SC1 and the second sub-chamber SC2 from the first inflation chamber MC1. After the first inflation chamber MC1 starts to inflate, the first sub-chamber SC1 and the second sub-chamber SC2 start to inflate. By the inflation gas IG flowing into the first sub-chamber SC1 and the second sub-chamber SC2 from the first inflation chamber MC1, the load applied to the occupant PO1 by the inflated first inflation chamber MC1 can be relieved. The first sub-chamber SC1, the second sub-chamber SC2, and the third sub-chamber SC3 described later are also referred to as "sub-inflation chambers". 【0022】 The second inflation chamber MC2 is deployed to the right side of the rear seat of the vehicle MV by being inflated with the inflation gas IG. The second inflation chamber MC2 mitigates the impact on the occupant PO2 sitting in the rear seat of the vehicle MV. 【0023】 The second inflation chamber MC2 and the third sub-chamber SC3 are connected by the third flow path MO21. The inflation gas IG flows into the third sub-chamber SC3 from the second inflation chamber MC2. After the second inflation chamber MC2 starts to inflate, the third sub-chamber SC3 starts to inflate. By the inflation gas IG flowing into the third sub-chamber SC3 from the second inflation chamber MC2, the load applied to the occupant PO2 by the inflated second inflation chamber MC2 can be relieved. 【0024】 The first inflation chamber MC1 and the second inflation chamber MC2 are connected by the fourth flow path MO22. 【0025】 The first flow path MO11 has constrictions NR1 and NR2. In Figure 2, constrictions NR1 and NR2 are enclosed by dashed-dotted circles. The same applies to other constrictions described later. Constrictions NR1 and NR2 are located at the connection point between the first expansion chamber MC1 and the first sub-chamber SC1. In this specification, "constriction" refers to a configuration for controlling the flow of expansion gas IG, in which the area of ​​the cross-section perpendicular to the direction of flow of expansion gas IG is narrower than the cross-sectional area of ​​the spaces connected upstream and downstream of the configuration. By having constrictions NR1 and NR2 in the first flow path MO11, the flow rate per unit time of expansion gas IG flowing from the first expansion chamber MC1 to the first sub-chamber SC1 can be adjusted. 【0026】 The second flow path MO12 has constricted sections NR3 and NR4. Constricted sections NR3 and NR4 are located at the connection point between the first expansion chamber MC1 and the second sub-chamber SC2. The presence of constricted sections NR3 and NR4 in the second flow path MO12 allows for adjustment of the flow rate per unit time of the expansion gas IG flowing from the first expansion chamber MC1 to the second sub-chamber SC2. 【0027】 The third flow path MO21 has a constricted section NR3. The constricted section NR3 is located at the connection point between the second expansion chamber MC2 and the third sub-chamber SC3. The presence of the constricted section NR3 in the third flow path MO21 allows for adjustment of the flow rate per unit time of the expansion gas IG flowing from the second expansion chamber MC2 to the third sub-chamber SC3. 【0028】 In this embodiment, a portion of the sutured portion 112 is sutured with a first stitching pitch. In Figure 2, the portion sutured with the first stitching pitch is shown by a thick dashed line. Another portion of the sutured portion 112 is sutured with a second stitching pitch. The portion sutured with the second stitching pitch is shown by a dotted line. The second stitching pitch is a larger stitching pitch than the first stitching pitch. In this specification, the stitching pitch is expressed as the length of one stitch. The first stitching pitch is, for example, 2.2 millimeters. The second stitching pitch is, for example, 3.0 millimeters. 【0029】 As shown in the figure, the portions of the sutured section 112 that constitute the first expansion chamber MC1 and the second expansion chamber MC2 are sutured with a first stitching pitch. The portions that constitute the first sub-chambers SC1 to the third sub-chambers SC3 are sutured with a second stitching pitch that is larger than the first stitching pitch. 【0030】 The constricted portions NR1 and NR2 of the first channel MO11 are sewn with a first sewing pitch smaller than the second sewing pitch. This is because stress is expected to concentrate in the constricted portions NR1 and NR2, and this is necessary to maintain the strength of the bag body 110. For the same reason, the portions constricted portions NR3 to NR5 are also sewn with the first sewing pitch. 【0031】 Figure 3 is a flowchart illustrating the manufacturing method of the bag body 110. In the process shown in Figure 3, sewing is performed to manufacture the portion that partitions the expansion chamber. The bag body 110 is sewn using a programmable electronic sewing machine. The programmable electronic sewing machine performs sewing based on sewing data that defines the seam formation position, sewing pitch, etc. The sewing data includes the seam formation position, the start and end positions of sewing with a first sewing pitch, and the start and end positions of sewing with a second sewing pitch. Prior to the start of sewing, the sewing data is stored in the memory of the programmable electronic sewing machine. In addition, the operator has already performed tasks such as attaching the sewing needle and positioning the base fabric. 【0032】 In step S101, sewing data is read from memory. In step S102, it is determined based on the sewing data whether the sewing pitch is the first sewing pitch or not. The process in step S102 is performed by the processor of the programmable electronic sewing machine. If it is determined that sewing will be done at the first sewing pitch (step S102; YES), the process in step S103 is executed. If it is determined that sewing will not be done at the first sewing pitch (step S102; NO), the process in step S104 is executed. Determining that sewing will not be done at the first sewing pitch means that sewing will be done at the second sewing pitch. 【0033】 In step S103, sewing is performed using the first sewing pitch until the next switching position of the sewing pitch. Step S103 is also called the "first process". In step S104, sewing is performed using the second sewing pitch until the next switching position of the sewing pitch. Step S104 is also called the "second process". The sewing processes in steps S103 and S104 are performed by the operation of the sewing unit and moving unit of the programmable electronic sewing machine according to the control of the processor of the programmable electronic sewing machine. The sewing unit includes a sewing needle, a needle bar on which the sewing needle is attached and which can move up and down, a needle bar moving mechanism, etc. The moving unit is a mechanism for feeding the base fabric. 【0034】 In step S105, it is determined whether or not to continue sewing based on the sewing data. If it is determined that the sewing end position has not been reached based on the sewing data, it indicates that sewing should continue. The process in step S105 is performed by the processor of the programmable electronic sewing machine. If it is determined that sewing should continue (step S105; YES), the processes from step S102 onwards are executed again. If it is determined that sewing should not continue (step S105; NO), the process shown in Figure 3 is terminated. 【0035】 As shown in Figure 2, for example, if sewing starts from the starting position P0, sewing is first performed using the second sewing pitch. At the switching position P1, the sewing pitch is changed to the first sewing pitch. Sewing using the first sewing pitch is performed from the switching position P1. In this way, sewing using the first sewing pitch and sewing using the second sewing pitch are performed consecutively. Regardless of the sewing pitch, the sewing speed of the programmable electronic sewing machine is kept constant. Sewing speed represents the number of stitches produced per unit time. 【0036】 As described above, in this embodiment, the portions that partition the first sub-chamber SC1, the second sub-chamber SC2, and the third sub-chamber SC3 are sewn with a second sewing pitch, which is larger than the portions that partition the first expansion chamber MC1 and the second expansion chamber MC2. This reduces the overall sewing time compared to an embodiment in which all portions that partition the first expansion chamber MC1, the second expansion chamber MC2, the first sub-chamber SC1, the second sub-chamber SC2, and the third sub-chamber SC3 are sewn with the first sewing pitch. 【0037】 The first expansion chamber MC1 and the second expansion chamber MC2 begin to expand before the first sub-chamber SC1, the second sub-chamber SC2, and the third sub-chamber SC3 when the vehicle MV is subjected to an impact. Thus, the first expansion chamber MC1 and the second expansion chamber MC2 are the main expansion chambers for protecting the occupants PO1 and PO2. For this reason, the first expansion chamber MC1 and the second expansion chamber MC2 are required to maintain sufficient strength. On the other hand, the first sub-chamber SC1, the second sub-chamber SC2, and the third sub-chamber SC3 are provided to mitigate the impact that occupants PO1 and PO2 receive from the first expansion chamber MC1 and the second expansion chamber MC2 by releasing the expansion gas IG from them. Therefore, it is assumed that the pressure on the first sub-chamber SC1, the second sub-chamber SC2, and the third sub-chamber SC3 is lower than that on the first expansion chamber MC1 and the second expansion chamber MC2. Therefore, the strength required for the first sub-chamber SC1, the second sub-chamber SC2, and the third sub-chamber SC3 is not higher than the strength that the first inflation chamber MC1 and the second inflation chamber MC2 must maintain. Even if the portions separating the first sub-chamber SC1, the second sub-chamber SC2, and the third sub-chamber SC3 are sewn with a large stitch pitch, the overall functionality of the bag body 110 will not be significantly reduced. According to this embodiment, it is possible to shorten the manufacturing time while maintaining the performance of the curtain airbag device 100. 【0038】 The constricted sections NR1 to NR5, where stress is expected to concentrate, are sewn with a first sewing pitch that is smaller than the second sewing pitch. This allows for a reduction in overall sewing time while maintaining the strength of the airbag. 【0039】 B. Other embodiments: (B1) For the constricted sections NR1 to NR5, it is sufficient to sew them with a stitching pitch smaller than the second stitching pitch, so they do not need to be sewn with the first stitching pitch. The strength of the airbag can be maintained by sewing the parts constituting the constricted sections NR1 to NR5, where stress concentration is expected, with a stitching pitch smaller than the second stitching pitch. 【0040】 (B2) In the above embodiment, an example was described in which the first sewing pitch is 2.2 millimeters and the second sewing pitch is 3.0 millimeters. However, the first and second sewing pitches are not limited to these. However, it is preferable that the difference between the first sewing pitch and the second sewing pitch is 0.5 millimeters or more and 1.0 millimeter or less. By providing a certain difference between the first and second sewing pitches, the overall sewing time can be shortened. 【0041】 (B3) The parts to be sewn with a first stitching pitch and the parts to be sewn with a second stitching pitch may be determined based on the results of a simulation performed prior to the manufacture of the airbag to analyze the areas where stress is concentrated when the inflation gas IG is supplied. This makes it possible to suppress the occurrence of problems in which the curtain airbag device 100 does not function properly due to, for example, damage to the stitching of the bag body 110 when the curtain airbag device 100 is activated. 【0042】 (B4) The position where the sewing pitch is switched may be set at a position where the direction of the curve represented by the stitch changes significantly. For example, a stitch representing a curve may be formed after a stitch representing a nearly straight line. In this case, the sewing pitch may be switched at the position where the nearly straight line changes to a curve. Whether or not a stitch represents a nearly straight line is determined from the shape represented by a predetermined number of stitches. For example, a value of 5 or more and 10 or less is set as the predetermined number. Whether or not a stitch represents a curve can be determined in the same way. Also, a stitch representing a nearly straight line may be formed after a stitch representing a curve. In this case, the sewing pitch may be switched at the position where the curve changes to a nearly straight line. In this way, the position where the sewing pitch is switched can be easily identified. 【0043】 Furthermore, the position where the direction of the curve represented by the stitching changes significantly may be identified as follows: First, the curve represented by the stitching is divided into a series of consecutive sections. At the boundary of each section, a tangent line to the curve and a normal line perpendicular to this tangent line are set. When N consecutive sections (where N is an integer of 2 or more) are observed, the position where the direction of the normal line reverses is considered to be the position where the direction of the curve represented by the stitching changes significantly. The sewing pitch may be switched at this position. The position where the sewing pitch is switched may also be set on the curve that constitutes the constricted portion. More preferably, the position where the sewing pitch is switched is set on the curve that constitutes the constricted portion, and is closer to the secondary expansion chamber than the main expansion chamber. 【0044】 (B5) The flow path does not have to have a constricted portion. In this case, the entire portion that defines the flow path may be sewn with the second stitching pitch. 【0045】 This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be replaced or combined as appropriate to solve some or all of the above-described problems, or to achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of symbols] 【0046】 100...Curtain airbag device, 110...Bag body (curtain airbag body), 112...Suture section, 120...Inner tube, 120a...Connection opening, 130...Inflator, DD...Downward, FD...Forward, IG...Inflation gas, MC1...First inflation chamber, MC2...Second inflation chamber, MO11...First passage, MO12...Second passage, MO21...Third passage, MO22...Fourth passage, MV...Vehicle, MVp1...Pillar, MVw1,MVw2...Side window, NR1~NR4...Narrow section, PO1,PO2...Occupant, RD...Rear, SC1...First sub-chamber, SC2...Second sub-chamber, SC3...Third sub-chamber, UD...Upward

Claims

[Claim 1] A method for manufacturing a curtain airbag, The aforementioned curtain airbags When expansion gas is supplied, at least one main expansion chamber expands and unfolds, Connected to the main expansion chamber, at least one secondary expansion chamber expands and unfolds after the main expansion chamber begins to expand, Equipped with, The aforementioned manufacturing method is A first step involves sewing together at least two airbag base fabrics at a first stitch pitch to define the portion that partitions the main inflation chamber, The second step includes sewing the portion that partitions the sub-inflation chamber with a second sewing pitch which is larger than the first sewing pitch, while the at least two airbag base fabrics are stacked together. Manufacturing method. [Claim 2] A manufacturing method according to claim 1, The aforementioned curtain airbags The system further comprises at least one flow path connecting the main expansion chamber and the secondary expansion chamber, The flow path is provided with at least one constricted portion at the connection point between the main expansion chamber and the secondary expansion chamber, In the second step, with the at least two airbag base fabrics stacked on top of each other, the portion constituting the constricted area is sewn together with the first sewing pitch. Manufacturing method. [Claim 3] A manufacturing method according to claim 1 or 2, The switching between the first and second processes is performed at the point where the direction of the stitching changes. Manufacturing method. [Claim 4] A manufacturing method according to claim 3, Based on the results of a simulation performed prior to the first and second steps to analyze the areas where stress concentrates when the expansion gas is supplied, the parts to be sewn with the first sewing pitch and the parts to be sewn with the second sewing pitch are determined. Manufacturing method. [Claim 5] A manufacturing method according to claim 1, The difference between the first sewing pitch and the second sewing pitch is set to be 0.5 millimeters or more and 1.0 millimeter or less. Manufacturing method. [Claim 6] A curtain airbag having multiple inflation chambers, The aforementioned plurality of inflation chambers are defined by at least two airbag base fabrics that are overlapped and sewn together. The aforementioned plurality of expansion chambers are When expansion gas is supplied, at least one main expansion chamber expands and unfolds, Connected to the main expansion chamber, at least one secondary expansion chamber expands and unfolds after the main expansion chamber begins to expand, Equipped with, The portion that partitions the main expansion chamber and the portion that constitutes the constricted section of the flow path connecting the main expansion chamber and the sub-expansion chamber are sewn together with a predetermined sewing pitch, which is a first sewing pitch. The portion that partitions the sub-expansion chamber is sewn with a second sewing pitch, which is a larger sewing pitch than the first sewing pitch. Curtain airbags. [Claim 7] A curtain airbag according to claim 6, At a position where the direction of the stitch changes, either the first stitch pitch or the second stitch pitch is switched to the other. Curtain airbags. [Claim 8] A curtain airbag according to claim 7, The difference between the first sewing pitch and the second sewing pitch is set to be 0.5 millimeters or more and 1.0 millimeter or less. Curtain airbags.

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