Pretensioner, method for assembling a pretensioner, and seat belt device

Abstract

This pretensioner provides a simple configuration that more reliably ensures airtightness at the communication point between the cylinder and the housing. [Solution] The pretensioner 1 includes a gas generator 5 that supplies gas to a communication section 62 communicating with a cylinder 4 to actuate a piston 3 in the direction of pulling in the wire 2, and a housing 6 that houses the communication section 62 and connects the cylinder 4 to a position communicating with the communication section 62. The cylinder 4 has an enlarged diameter section 42 at the end on the side where it is connected to the housing 6. The cylinder 4 has a plurality of crimped sections 43 formed by crimping a portion of the enlarged diameter section 42 that extends from the connection section 65 of the housing 6 toward the base end toward the axial end toward the axial side. Between the boundary section 70 of the housing 6 and the communication section 62, there is a projection 71 that engages with the annular groove 83 of the wire guide 8 when the wire guide 8 is installed on the boundary section 70.

Description

Technical Field

[0001] The present disclosure relates to a pretensioner, a method for assembling the pretensioner, and a seat belt device.

Background Art

[0002] In vehicle seat belt devices, a configuration has been proposed in which a pretensioner is provided that operates in an emergency such as a vehicle collision to retract a retracted member such as a webbing or a buckle, thereby increasing the restraining force of the webbing on the vehicle occupant.

[0003] Patent Document 1 describes that threading processing is performed on both the pressure vessel (housing) and the cylinder, and discloses a configuration in which the housing and the cylinder are connected by screw fastening.

[0004] Patent Document 2 discloses a configuration in which the installation position of a seal member disposed inside a pressure vessel is restricted by a tubular restraining member.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of Invention

Problems to be Solved by the Invention

[0006] The conventional techniques described in Patent Document 1 and the like have a problem that the number of man-hours increases because threading processing and the like are required. The conventional techniques described in Patent Document 2 and the like have a problem that it is necessary to use a separate component for positioning the seal member, which increases the number of components.

[0007] The present disclosure aims to provide a pretensioner that can more reliably ensure airtightness of the communication portion between the cylinder and the housing with a simple configuration. [Means for solving the problem]

[0008] A pretensioner according to one aspect of an embodiment of the present invention is a pretensioner that operates in an emergency to increase the restraining force on a vehicle occupant by webbing by pulling in a member to be pulled in, comprising: a wire with one end connected to the member to be pulled in; a piston connected to the other end of the wire; a cylinder that slidably houses the piston; a gas generator that supplies gas to a communication part communicating with the cylinder for operating the piston in the direction of pulling in the wire; a housing that houses the communication part and connects the cylinder to a position communicating with the communication part; an insertion hole provided in the housing for guiding the wire to the communication part; and a wire guide installed at the boundary between the insertion hole and the communication part, sealing the boundary and allowing the wire to be inserted through a hole provided in the center, wherein the cylinder has an enlarged diameter portion at the end on the side connected to the housing, and the housing is inserted into the body of the cylinder The cylinder has a tip portion, and a connecting portion that is positioned on the base end side of the tip portion and is formed to be larger in diameter than the tip portion, with a stepped surface at one end between it and the tip portion and an end surface at the other end facing in the opposite direction to the stepped surface, wherein the enlarged diameter portion is formed to extend toward the base end side from the other end of the connecting portion when the connecting portion is inserted into the enlarged diameter portion to a position where the stepped surface of the connecting portion abuts against the innermost stepped surface of the enlarged diameter portion, the cylinder has a crimped portion formed by crimping at least a part of the extending portion of the enlarged diameter portion toward the axial side, the wire guide has a first portion formed to be the same shape as the inner circumferential surface of the communication portion, a second portion formed to be able to fit into the boundary portion, and a first engaging portion provided between the first portion and the second portion, between the boundary portion and the communication portion of the housing therefor a second engaging portion that engages with the first engaging portion when the wire guide is installed on the boundary portion. [Effects of the Invention]

[0009] According to this disclosure, a pretensioner can be provided that can more reliably ensure airtightness of the communication portion between the cylinder and the housing with a simple configuration. [Brief explanation of the drawing]

[0010] [Figure 1] Configuration diagram of a seat belt device according to an embodiment [Figure 2] Perspective view of a pretensioner according to an embodiment [Figure 3] Figure 2 shows an exploded perspective view of the pretensioner. [Figure 4] Longitudinal section of the pretensioner shown in Figure 2. [Figure 5] Enlarged view of the area around the housing's connecting section in Figure 4. [Figure 6] Perspective view of the housing as seen from the negative X direction side. [Figure 7] Diagram showing the first step in the procedure for connecting the cylinder and the housing. [Figure 8] Perspective view showing an example of a cylinder with a crimped section formed. [Figure 9] Diagram showing the second step in the procedure for connecting the cylinder and housing. [Figure 10] Perspective view showing another example of a cylinder with a crimped section formed. [Figure 11] Diagram illustrating the effect of the wire guide according to the embodiment. [Modes for carrying out the invention]

[0011] The embodiments will be described below with reference to the attached drawings. To facilitate understanding of the explanation, the same reference numerals are used for identical components in each drawing whenever possible, and redundant explanations are omitted.

[0012] Note that in the following description, the X direction, Y direction, and Z direction are directions perpendicular to each other. Typically, the X direction and the Y direction are horizontal directions, and the Z direction is the vertical direction. The X direction is the sliding direction of the piston 3, and the direction in which the ferrule 22 (retracted member) is retracted is the X positive direction. Further, the X direction is the vehicle front-rear direction when the pretensioner 1 is installed in the vehicle, the X positive direction side is the vehicle front side, and the X negative direction side is the vehicle rear side. The Y direction is the vehicle width direction when the pretensioner 1 is installed in the vehicle.

[0013] <Configuration of Seatbelt Device> FIG. 1 is a configuration diagram of the seatbelt device 100 according to the embodiment. FIG. 1 shows an example of a state in which the seatbelt device 100 is mounted on a vehicle. The seatbelt device 100 includes a webbing 101, a retractor 102, a tongue 105, a buckle 107, and a pretensioner 1.

[0014] The webbing 101 is a belt-shaped member for restraining an occupant seated on the seat 108. One end 103 of the webbing 101 is connected to the retractor 102, and the other end 106 of the webbing 101 is connected to the pretensioner 1.

[0015] The retractor 102 is a winding device that enables winding or unwinding of the webbing 101, and restricts the webbing 101 from being pulled out from the main body portion of the retractor 102 when an acceleration equal to or greater than a predetermined value is detected, such as during a vehicle collision. The retractor 102 is fixed to a vehicle body portion on the side of the backrest portion 109 of the seat 108 (for example, a lower portion of a pillar to which the shoulder anchor 104 is fixed).

[0016] The tongue 105 is a plate-shaped member slidably attached to the webbing 101 between the pretensioner 1 and the shoulder anchor 104.

[0017] The buckle 107 is the component to which the tongue 105 is attached and detached. The buckle 107 is fixed to the seat portion 110 of the seat 108 on the side opposite the retractor 102.

[0018] As the tongue 105 is connected to the buckle 107, the occupant's chest on the seat 108 is restrained by the shoulder belt portion 101b of the webbing 101, and the occupant's waist is restrained by the lap belt portion 101a of the webbing 101. The shoulder belt portion 101b is the portion of the webbing 101 between the shoulder anchor 104 and the tongue 105, and the lap belt portion 101a is the portion of the webbing 101 between the tongue 105 and the pretensioner 1.

[0019] The pretensioner 1 is a lap pretensioner that instantly pulls in the lap belt portion 101a of the webbing 101 when an acceleration exceeding a predetermined value is detected, such as during a vehicle collision, thereby reducing the slack between the occupant's waist and the lap belt portion 101a. The pretensioner 1 is normally fixed to the vehicle body portion closer to the door on the outer side of the seat portion 110.

[0020] <Pretensioner Configuration> Figure 2 is a perspective view of the pretensioner 1 according to an embodiment. Figure 3 is an exploded perspective view of the pretensioner 1 shown in Figure 2. Figure 4 is a longitudinal cross-sectional view of the pretensioner 1 shown in Figure 2. Figure 5 is an enlarged view of the area around the communication portion 62 of the housing 6 in Figure 4.

[0021] The pretensioner 1 is a device that activates in an emergency to increase the restraining force on the vehicle occupant by the webbing 101 by pulling in the member to be retracted. As shown in Figures 2 to 4, the pretensioner 1 comprises a wire 2 connected to the webbing 101 that restrains the occupant, a piston 3 positioned on the wire 2, a cylinder 4 that slidably houses the piston 3, a gas generator 5 that provides driving force to the piston 3, a housing 6 that integrally connects the cylinder 4 and the gas generator 5, and a bracket 7 connected to the housing 6 for positioning the wire 2.

[0022] The housing 6 includes an insertion hole 61 for guiding the wire 2, a communication section 62 that communicates with the cylinder 4 and the insertion hole 61, and a gas supply port 63 for supplying gas generated by the gas generator 5 to the communication section 62. A wire guide 8 is positioned at the boundary 70 between the insertion hole 61 and the communication section 62.

[0023] The pretensioner 1 functions as a belt anchor and is fixed to the vehicle body by inserting a cylindrical member 11 through fixing holes 7a and 7b formed in the bracket 7 and a fixing hole 6a formed in the housing 6, and then inserting a bolt 9 (see Figure 1) through this cylindrical member 11. The bracket 7 is equipped with a guide hole 7c and a guide portion 7d, and when the bracket 7 is integrally assembled to the housing 6, the wire 2 is inserted through the guide hole 7c, along the guide portion 7d, and then through the insertion hole 61 of the housing 6, thereby maintaining the bending angle of the wire 2.

[0024] A ferrule 22 is connected to one end of the wire 2 via a holder (not shown) or the like. The ferrule 22 is connected to the end of the wrap belt 101a of the webbing 101, as shown in Figure 1.

[0025] The other end of the wire 2 is inserted into the housing 6 via the bracket 7 and connected to the wire end 21 inside the cylinder 4. A piston 3 is slidably positioned inside the cylinder 4, and the wire 2 is inserted into the piston 3 before being connected to the wire end 21.

[0026] As shown in Figures 3 to 5, the gas generator 5 is positioned within an opening (gas generator mounting section 64) formed in the housing 6 and fixed to the housing 6. The gas supply port 63 is formed by a passage connecting this gas generator mounting section 64 and the communication section 62.

[0027] Furthermore, the gas generator 5 is connected, for example, to an acceleration sensor (not shown) that detects vehicle collisions, and activates during a vehicle collision to inject high-pressure gas into the communication section 62 via the gas supply port 63 of the housing 6. The gas generator 5 generates gas, for example, by an internally built-in explosive. The high-pressure gas injected into the communication section 62 of the housing 6 presses against the piston 3, causing it to move away from the housing 6 (positive X direction). As the piston 3 moves, the wire 2 is pulled into the housing 6 and cylinder 4, tightening the webbing 101 (wrap belt 101a).

[0028] The housing 6 is made of a material with a lower specific gravity than iron (for example, aluminum, aluminum alloy, etc.). Specifically, the housing 6 may be manufactured by aluminum die casting. By using a material with a lower specific gravity than iron, the weight of the housing 6 can be reduced.

[0029] Furthermore, the housing 6 has an insertion hole 61 at one end (X-negative direction side) for guiding the wire 2 from the bracket 7 to the cylinder 4, and a connecting portion 65 at the other end (X-positive direction side) for connecting the cylinder 4. The wire 2 is inserted into the insertion hole 61, and the enlarged diameter portion 42 provided at the X-negative end of the cylinder 4 is fitted to the outer circumference of the connecting portion 65. A communication portion 62 is formed between the insertion hole 61 and the connecting portion 65, communicating with them.

[0030] The connecting portion 65 is formed to protrude radially outward from the adjacent outer surface of the housing 6 (see Figure 6, etc.). Furthermore, an insertion portion 66 is formed at the tip further towards the positive X direction from the connecting portion 65, and has a smaller outer diameter than the connecting portion 65. The outer diameter of the insertion portion 66 is approximately the same as the inner diameter of the body 41 of the cylinder 4, thereby enabling the insertion portion 66 to be inserted into the body 41 of the cylinder 4.

[0031] This configuration of the connecting portion 65 and the insertion portion 66 creates a stepped surface 67 facing the positive X direction between the connecting portion 65 and the insertion portion 66. Furthermore, as described above, an enlarged diameter portion 42 with a larger inner diameter than the main body 41 is provided at the X-negative end of the cylinder 4. This creates a stepped surface 44 facing the negative X direction between the main body 41 and the enlarged diameter portion 42 of the cylinder 4. Therefore, when the cylinder 4 is assembled to the connecting portion 65 of the housing 6, the stepped surface 44 of the cylinder 4 abuts against the stepped surface 67 of the housing 6, thereby positioning the relative positions of the cylinder 4 and the housing 6 in the X direction. At this time, the insertion portion 66 of the housing 6 is inserted into the main body 41 of the cylinder 4, allowing the connecting portion 65 and the communication portion 62 of the housing 6 to be positioned coaxially with the cylinder 4.

[0032] The tip portion of the enlarged diameter section 42 of the cylinder 4 on the negative X-direction side is formed to extend further in the negative X-direction than the end portion of the connecting section 65 of the housing 6 on the negative X-direction side. A portion of this tip is then crimped toward the axis to form a crimped section 43. Preferably, multiple crimped sections 43 (for example, 3 or 5) are formed at approximately equal intervals along the circumferential direction of the enlarged diameter section 42. By providing such crimped sections 43, it is possible to prevent the cylinder 4 from coming out of the housing 6.

[0033] As the cylinder 4 is assembled to the housing 6 in this manner, the crimped portion 43 of the cylinder 4 presses the end face of the connection portion 65 of the housing 6 on the X-negative side in the axial direction (X-positive side). As a result, the stepped surface 67, which is the X-positive side end face of the connection portion 65, presses the stepped surface 44 of the cylinder 4 in the X-positive direction. This makes it possible to firmly bring the stepped surface 67 of the housing 6 and the stepped surface 44 of the cylinder 4 into close contact, and the axial force due to the crimping of the crimped portion 43 ensures airtightness between the stepped surface 67 and the stepped surface 44, thus ensuring airtightness of the communication portion 62 between the cylinder 4 and the housing 6.

[0034] Furthermore, when the cylinder 4 is assembled to the housing 6 in this manner, the piston 3, when positioned at the X-negative end of the cylinder 4's body 41, will abut against the tip of the insertion portion 66 of the housing 6, thereby restricting further movement of the piston 3 in the X-negative direction.

[0035] The inner circumferential surface of the communication portion 62 on the insertion hole 61 side forms a conical surface that decreases in diameter as it approaches the insertion hole 61, and constitutes a boundary portion 70 between the insertion hole 61 and the communication portion 62. A resin wire guide 8 is inserted into this boundary portion 70. The wire guide 8 has a second portion 82 on the negative X direction side that is formed in a substantially frustoconical shape, and the boundary portion 70 can be sealed by fitting the second portion 82 onto the conical surface of the housing 6. The wire guide 8 has a hole in its center through which a wire 2 can be inserted. The wire guide 8 has the function of guiding the wire 2 to the communication portion 62 and sealing the boundary portion 70.

[0036] Furthermore, the wire guide 8 has a first portion 81 on the X-positive side that is formed in a substantially cylindrical shape. The outer shape of the first portion 81 is formed to be substantially the same as the inner diameter of the communication portion 62 of the housing 6, thereby enabling the first portion 81 of the wire guide 8 to be inserted into the X-negative end of the communication portion 62 of the housing 6.

[0037] Furthermore, as shown in Figure 5 and other figures, an annular groove 83 (first engaging portion) is provided between the first portion 81 and the second portion 82 of the wire guide 8, along the circumferential direction of the outer surface. On the other hand, when the wire guide 8 is installed in the communication portion 62 and the boundary portion 70, a projection 71 (second engaging portion) that can engage with the annular groove 83 is provided on the inner surface of the communication portion 62 opposite to the annular groove 83. The projection 71 is formed to protrude axially from the inner surface of the communication portion 62. The wire guide 8 can be installed in the boundary portion 70 of the housing 6 by inserting it into the communication portion 62 of the housing 6 from the X-positive side, for example, when the wire 2 is not inserted into the central hole, thereby fitting the annular groove 83 of the wire guide 8 into the projection 71 of the housing 6.

[0038] When the wire guide 8 is installed in the communication section 62 and the boundary section 70, the projection 71 of the housing 6 engages with the annular groove 83 of the wire guide 8, thereby positioning the relative position of the wire guide 8 in the X direction with respect to the housing 6. Furthermore, after fitting the annular groove 83 of the wire guide 8 into the projection 71 of the housing 6, inserting the wire 2 through the hole in the center of the wire guide 8 restricts the movement of the annular groove 83 toward the axial center, thus preventing the annular groove 83 from coming out of the projection 71. This allows the position of the wire guide 8 as a sealing member to be restricted without using additional parts.

[0039] In this embodiment, the first engaging portion of the wire guide 8 is an annular groove 83, i.e., concave, and the second engaging portion provided on the housing 6 that engages with the first engaging portion is a projection 71, i.e., convex. However, as long as the wire guide 8 can be positioned at a predetermined location on the boundary portion 70 and the communication portion 62 of the housing 6, the concave-convex relationship may be reversed. For example, the first engaging portion of the wire guide 8 may be convex, and the second engaging portion provided on the housing 6 that engages with the first engaging portion may be concave.

[0040] A tapered surface 32 is provided in the x-direction middle portion of the piston body 31. The tapered surface 32 is formed such that its outer diameter increases from one end (negative X direction side) to the other end (positive X direction side) of the piston body 31. Balls 33 and a ball ring 34 are arranged on the tapered surface 32 to suppress the piston 3 from moving backward in the negative X direction. The ball ring 34 is positioned at the end of the tapered surface 32 on the negative X direction side, that is, at the part of the tapered surface 32 where the outer diameter is smallest. The balls 33 are normally biased from the negative X direction side by the ball ring 34. The balls 33 are formed with a diameter such that friction caused by contact with the inner circumferential surface of the cylinder 4 does not hinder the sliding of the piston 3 when the ball ring 34 is installed.

[0041] An annular groove is formed in the circumferential direction on the outer surface of the piston body 31 at a position on the X-negative side from the tapered surface 32. An O-ring 35 is fitted into this annular groove to improve the airtightness of the gap between the outer surface of the piston body 31 and the inner surface of the cylinder 4. A washer 10 is also placed between the X-positive end face of the piston body 31 and the wire end 21.

[0042] <Connection structure between cylinder and housing> Figure 6 is a perspective view of the housing 6 from the negative X direction. Figure 6 is a view of the housing 6 from the opposite side to Figures 1 to 3.

[0043] As shown in Figure 6, multiple sets of inclined surfaces 68 and protrusions 69 are provided alternately and continuously along the circumferential direction on the X-negative end face of the connection portion 65 of the housing 6. When viewed from the X-negative side, the inclined surface 68 is formed so that one end is most recessed toward the X-positive side, and as it proceeds counterclockwise along the circumferential direction, it continuously protrudes toward the X-negative side. In other words, when the connection portion 65 is viewed from the outside in the circumferential direction, the inclined surface 68 is formed at an inclination with respect to the YZ plane. The protrusion 69 is one end of the inclined surface 68 that protrudes most toward the X-positive side. Furthermore, the protrusion 69 connects to the other end of another adjacent inclined surface that is most recessed toward the X-negative side, in a counterclockwise direction.

[0044] The number of sets of inclined surfaces 68 and protrusions 69 provided on the connecting portion 65 is the same as the number of crimping portions 43 provided on the enlarged diameter portion 42 of the cylinder 4.

[0045] Figure 7 shows the first step in the procedure for connecting the cylinder 4 and the housing 6. In Figure 7 and Figure 9 (described later), the housing 6 is depicted in a perspective view from the same viewpoint as in Figure 6.

[0046] In the first stage shown in Figure 7, the enlarged diameter portion 42 of the cylinder 4 moves from the positive X direction to the negative X direction, as indicated by arrow A, and is fitted to the outer circumferential surface of the connecting portion 65 of the housing 6. As explained with reference to Figure 5, the enlarged diameter portion 42 is inserted until the stepped surface 44 at the negative X direction end abuts against the stepped surface 67 at the positive X direction end of the connecting portion 65.

[0047] After the insertion of the cylinder 4 is complete, as shown by arrow B in Figure 7, a portion of the tip of the enlarged diameter portion 42 of the cylinder 4 on the X-negative side is crimped toward the axis to form multiple crimped portions 43. In the first stage, the crimped portions 43 are formed on the X-negative side end face of the housing 6 connection portion 65, in the portion that overlaps with the inclined surface 68. Preferably, the position where the crimped portions 43 are formed is the portion of the inclined surface 68 that is most recessed in the X-positive direction on the clockwise side when viewed from the X-negative direction. This makes the crimping process of the crimped portions 43 easier and allows for a larger amount of crimping toward the X-positive side.

[0048] Figure 8 is a perspective view showing an example of a cylinder 4 with the crimped portions 43 formed. In Figure 8, the cylinder is viewed from the negative X direction side, i.e., the enlarged diameter portion 42 side, and the entirety of the multiple crimped portions 43 is shown. As shown in Figure 8, in this embodiment, five crimped portions 43 are provided at approximately equal intervals along the circumferential direction of the enlarged diameter portion 42. In other words, in the examples of Figures 7 and 8, each crimped portion 43 is arranged at a distance of approximately 72 degrees around the axis, and when adjacent crimped portions 43 are connected by line segments, they form a regular pentagon.

[0049] Figure 9 shows the second stage of the connection procedure between the cylinder 4 and the housing 6. In the second stage shown in Figure 9, the entire cylinder 4 is rotated counterclockwise in the negative X direction, as indicated by arrow C. As a result, the five crimping portions 43 move counterclockwise in the negative X direction along the inclined surface 68 of the connection portion 65 where each is located. In other words, they move from the portion of the inclined surface 68 that is more deeply recessed in the positive X direction relative to the YZ plane, to the direction in which the recess is smaller.

[0050] Ultimately, as shown in Figure 9, the five crimping portions 43 are positioned closest to the protrusions 69 on the inclined surface 68 of the connecting portion 65 where each is located. More preferably, the cylinder 4 is rotated until each crimping portion 43 rides up onto the protrusion 69 where it is located. This reduces the gap between each crimping portion 43 and the X-negative end face of the connecting portion 65 of the housing 6, thereby strengthening the connection between the crimping portion 43 and the connecting portion 65, and consequently strengthening the connection between the cylinder 4 and the housing 6.

[0051] By following the procedure shown in Figures 7 and 9, a crimped portion 43 can be formed on the enlarged diameter portion 42 of the cylinder 4, and it can be easily and reliably connected firmly to the connecting portion 65 of the housing 6.

[0052] Figure 10 is a perspective view showing another example of the cylinder 4 with the crimped portions 43 formed. The outline of Figure 10 is the same as that of Figure 8. In the examples of Figures 7 to 9, a configuration in which five crimped portions 43 are formed on the cylinder 4 is illustrated, but there can be any number of crimped portions 43, and not just five. For example, as shown in Figure 10, a configuration in which three crimped portions 43 are provided at approximately equal intervals along the circumferential direction of the enlarged diameter portion 42 is also possible. In the configuration illustrated in Figure 10, each crimped portion 43 is arranged approximately 120 degrees apart around the axis, and when adjacent crimped portions 43 are connected by line segments, they form an equilateral triangle.

[0053] It is preferable that the multiple crimping portions 43 are arranged at approximately equal intervals along the circumferential direction of the enlarged diameter portion 42. This allows the cylinder 4 to be connected to the housing 6 with approximately equal bonding force along the circumferential direction of the enlarged diameter portion 42. For the same reason, the multiple crimping portions 43 may also be arranged in a point-symmetrical manner with respect to the axis. In these cases, multiple crimping portions 43 are formed by crimping at least a portion of the portion of the enlarged diameter portion 42 that extends in the negative X direction from the connection portion 65 when attached to the housing 6 toward the axis. In these cases, it is preferable that three or more crimping portions 43 are provided.

[0054] Alternatively, the entire circumference of the enlarged diameter portion 42 may be crimped. This allows the cylinder 4 to be securely connected to the housing 6 with a more uniform bonding force along the circumference of the enlarged diameter portion 42. In this case, there will be only one crimped portion 43, rather than multiple.

[0055] The effects of this embodiment will now be explained. The pretensioner 1 according to this embodiment includes a gas generator 5 that supplies gas to a communication portion 62 communicating with a cylinder 4 to actuate a piston 3 in the direction of pulling in a wire 2, and a housing 6 that houses the communication portion 62 and connects the cylinder 4 to a position communicating with the communication portion 62. The cylinder 4 has an enlarged diameter portion 42 at the end on the side (negative X direction) where it is connected to the housing 6. The housing 6 has an insertion portion 66 that is inserted into the main body 41 of the cylinder 4, and a connecting portion 65 that is located on the base end side (negative X direction) of the insertion portion 66 and is formed to be larger in diameter than the insertion portion 66, with a stepped surface 67 provided at one end between it and the insertion portion 66, and an end surface at the other end facing in the opposite direction to the stepped surface 67. The enlarged diameter portion 42 of the cylinder 4 is formed to extend toward the base end from the other end of the connecting portion 65 when the connecting portion 65 is inserted into the enlarged diameter portion 42 to the point where the stepped surface 67 of the connecting portion 65 of the housing 6 abuts against the innermost stepped surface 44 of the enlarged diameter portion 42. The cylinder 4 has a plurality of crimped portions 43 formed by crimping toward the axial center a portion of the enlarged diameter portion 42 that extends toward the base end from the connecting portion 65 of the housing 6.

[0056] This configuration allows the cylinder 4 to be firmly connected to the housing 6 by inserting the enlarged diameter portion 42 of the cylinder 4 into the connection portion 65 of the housing 6 until the stepped surface 44 of the enlarged diameter portion 42 abuts against the stepped surface 67 of the housing 6, and then crimping a part of the tip of the enlarged diameter portion 42 to form a crimped portion 43. Furthermore, since there is no need to use methods such as screw fastening to connect the cylinder to the housing 6 as in the conventional technology, the connection structure between the cylinder 4 and the housing 6 can be made simpler. In addition, even with a simple configuration, airtightness of the communication portion 62 between the cylinder 4 and the housing 6 can be ensured.

[0057] Furthermore, the pretensioner 1 according to this embodiment includes a through hole 61 provided in the housing 6 for guiding the wire 2 to the communication portion 62, and a wire guide 8 installed at the boundary portion 70 between the through hole 61 and the communication portion 62, sealing the boundary portion 70 and allowing the wire 2 to be inserted through a hole provided in the center. The wire guide 8 has a first portion 81 formed in the same shape as the inner circumferential surface of the communication portion 62, a second portion 82 formed to be able to fit into the boundary portion 70, and an annular groove 83 as a first engaging portion provided between the first portion 81 and the second portion 82. Between the boundary portion 70 and the communication portion 62 of the housing 6, there is a projection 71 as a second engaging portion that engages with the first engaging portion (annular groove 83) when the wire guide 8 is installed at the boundary portion 70.

[0058] With this configuration, by inserting the wire guide 8 towards the boundary portion 70 until the annular groove 83, which serves as the first engaging portion, is fitted into the projection 71, which serves as the second engaging portion, the wire guide 8 can be easily positioned so that its second portion 82 seals the boundary portion 70 of the housing 6. Furthermore, since the first engaging portion and the second engaging portion are engaged, it is possible to prevent the second portion 82 of the wire guide 8 from moving away from the position that seals the boundary portion 70, thus more reliably maintaining the sealing function of the wire guide 8. In other words, unlike the conventional technology, there is no need to install other elements to restrict the movement of the sealing member in order to maintain the sealing function, thus avoiding an increase in the number of parts and allowing the sealing function of the wire guide 8 to be maintained with a simpler configuration.

[0059] Based on the above, the pretensioner 1 according to this embodiment can more reliably ensure airtightness of the communication portion 62 between the cylinder 4 and the housing 6 with a simple configuration.

[0060] Figure 11 is a diagram illustrating the effect of the wire guide 8 according to the embodiment. In Figure 11, the wire guide 8 positioned in a normal mounting position is shown by a dotted line.

[0061] In this embodiment, it is preferable that the projection 71 of the housing 6 is formed to be shearable by the annular groove 83 of the wire guide 8 when the pressure inside the communication portion 62 exceeds a predetermined value. Here, the predetermined value is, for example, an excessive pressure that may damage the communication portion 62 of the housing 6 or the cylinder 4, or cause the connection between the housing 6 and the cylinder 4 to detach.

[0062] As shown by arrow D in Figure 11, when the pressure inside the communication section 62 exceeds a predetermined value, excessive pressure is applied in the negative X direction to the end face of the wire guide 8 on the positive X direction side, i.e., the end face exposed inside the communication section 62. At this time, the annular groove 83 of the wire guide 8 also receives excessive pressure in the negative X direction, and this is transmitted to the engaged projection 71, so as shown by arrow E in Figure 11, the projection 71 is sheared in the negative X direction. As a result, the positional restriction of the wire guide 8 is released, and the wire guide 8 moves from its normal position (shown by the dotted line) to the negative X direction in response to pressure D, and exits to the outside through the insertion hole 61. This eliminates the airtightness of the communication section 62, and thus reduces the pressure inside the communication section 62. In other words, by controlling the shear area of ​​the projection 71, the wire guide 8 can be made to function as a simple vent.

[0063] The embodiments have been described above with reference to specific examples. However, this disclosure is not limited to these specific examples. Modifications made to these specific examples by those skilled in the art are also included within the scope of this disclosure, as long as they retain the features of this disclosure. The elements, their arrangement, conditions, shapes, etc., of each of the aforementioned specific examples are not limited to those illustrated and can be modified as appropriate. The elements of each of the aforementioned specific examples can be combined in different ways as appropriate, as long as no technical inconsistencies arise.

[0064] In the above embodiment, a wrap pretensioner in which the retracted member of the pretensioner 1 is the wrap belt portion of the webbing was illustrated, but a buckle pretensioner in which the retracted member is the buckle 107 may also be used. [Explanation of symbols]

[0065] 1 Pretensioner 2 wires 3 pistons 4 cylinders 41 Main unit 42 Expanded diameter part 43 Crimping section 44 Step surface 5. Gas generator 6 Housing 61 Through hole 62 Communication part 65 Connection part 66 Insertion section 67 Step surface 70 Boundary 71 Protrusion (second engagement part) 8 Wire guides 81 Part 1 82 Part 2 83 Annular groove (first engagement portion)

Claims

1. A pretensioner that activates in an emergency and increases the restraining force on the vehicle occupant by webbing by pulling in the retractable member, A wire, with one end connected to the member to be pulled in, A piston connected to the other end of the wire, A cylinder that slidably houses the piston, A gas generator supplies gas to a communication section connected to the cylinder to operate the piston in the direction of pulling in the wire, A housing that houses the aforementioned communication portion and connects the cylinder to a position that communicates with the aforementioned communication portion, The housing is provided with an insertion hole for guiding the wire to the communication portion, A wire guide is installed at the boundary between the insertion hole and the communication portion, sealing the boundary portion and allowing the wire to be inserted through a hole provided in the center, Equipped with, The cylinder has an enlarged diameter portion at the end on the side where it connects to the housing, The housing has an insertion portion that is inserted into the body of the cylinder, and a connecting portion that is positioned on the base end side of the insertion portion and is formed to be larger in diameter than the insertion portion, with a stepped surface provided at one end between it and the insertion portion, and an end surface provided at the other end facing in the opposite direction to the stepped surface, The enlarged diameter portion is formed to extend toward the base end from the other end of the connecting portion when the connecting portion is inserted into the enlarged diameter portion to the point where the stepped surface of the connecting portion abuts against the innermost stepped surface of the enlarged diameter portion. The cylinder has a crimped portion formed by crimping at least a part of the extended portion of the enlarged diameter portion toward the axial center, The wire guide has a first portion formed in the same shape as the inner circumferential surface of the communication portion, a second portion formed to be able to fit into the boundary portion, and a first engaging portion provided between the first portion and the second portion. Between the boundary portion and the communication portion of the housing, a second engaging portion is provided which engages with the first engaging portion when the wire guide is installed on the boundary portion. Pretensioner.

2. Multiple crimping portions are arranged at approximately equal intervals along the circumferential direction of the enlarged diameter portion. The pretensioner according to claim 1.

3. The crimping portion is provided in three or more locations along the circumferential direction of the enlarged diameter portion. The pretensioner according to claim 1.

4. The crimped portion is formed over the entire circumference in the circumferential direction of the enlarged diameter portion. The pretensioner according to claim 1.

5. Multiple crimping portions are arranged along the circumferential direction of the enlarged diameter portion. The connecting portion has the same number of inclined surfaces formed along the circumferential direction and inclined axially on the end face of the other end that is positioned to contact the crimped portion, The inclined surface is formed such that one end is recessed in the axial direction relative to the other end. Each of the aforementioned multiple crimping portions is positioned at the other end of each of the aforementioned multiple inclined surfaces. The pretensioner according to claim 1.

6. The first engaging portion is an annular groove provided on the outer surface of the wire guide along the circumferential direction, The second engaging portion is a projection that protrudes from the inner circumferential surface of the communicating portion toward the axial center. The pretensioner according to claim 1.

7. The projection of the housing is formed to be shearable by the annular groove of the wire guide when the pressure in the communication portion exceeds a predetermined value. The pretensioner according to claim 6.

8. A pretensioner that activates in an emergency and increases the restraining force on the vehicle occupant by webbing by pulling in the retractable member, A wire, with one end connected to the member to be pulled in, A piston connected to the other end of the wire, A cylinder that slidably houses the piston, A gas generator supplies gas to a communication section connected to the cylinder to operate the piston in the direction of pulling in the wire, A housing that houses the aforementioned communication portion and connects the cylinder to a position that communicates with the aforementioned communication portion, Equipped with, The cylinder has an enlarged diameter portion at the end on the side where it connects to the housing, The housing has a tip portion that is inserted into the body of the cylinder, and a connecting portion that is positioned on the base end side of the tip portion and is formed to be larger in diameter than the tip portion, with a stepped surface provided at one end between it and the tip portion, and an end surface provided at the other end facing in the opposite direction to the stepped surface, The enlarged diameter portion is formed to extend toward the base end from the other end of the connecting portion when the connecting portion is inserted into the enlarged diameter portion to the point where the stepped surface of the connecting portion abuts against the innermost stepped surface of the enlarged diameter portion. The cylinder has a crimped portion formed by crimping at least a part of the extended portion of the enlarged diameter portion toward the axial center. Pretensioner.

9. A method for assembling a pretensioner that activates in an emergency and increases the restraining force of the vehicle occupant by the webbing by pulling in the member to be retracted, The aforementioned pretensioner is, A wire, with one end connected to the member to be pulled in, A piston connected to the other end of the wire, A cylinder that slidably houses the piston, A gas generator supplies gas to a communication section connected to the cylinder to operate the piston in the direction of pulling in the wire, A housing that houses the aforementioned communication portion and connects the cylinder to a position that communicates with the aforementioned communication portion, Equipped with, The cylinder has an enlarged diameter portion at the end on the side where it connects to the housing, The housing has a tip portion that is inserted into the body of the cylinder, and a connecting portion that is positioned on the base end side of the tip portion and is formed to be larger in diameter than the tip portion, with a stepped surface provided at one end between it and the tip portion, and an end surface provided at the other end facing in the opposite direction to the stepped surface, The enlarged diameter portion is formed to extend toward the base end from the other end of the connecting portion when the connecting portion is inserted into the enlarged diameter portion to the point where the stepped surface of the connecting portion abuts against the innermost stepped surface of the enlarged diameter portion. The cylinder has a crimped portion formed by crimping at least a part of the extended portion of the enlarged diameter portion toward the axial center, Multiple crimping portions are arranged along the circumferential direction of the enlarged diameter portion. The connecting portion has the same number of inclined surfaces formed along the circumferential direction and inclined axially on the end face of the other end that is positioned to contact the crimped portion, The inclined surface is formed such that one end is recessed in the axial direction relative to the other end. Insertion step: Insert the tip of the housing into the body of the cylinder, insert the connecting portion of the housing into the enlarged diameter portion of the cylinder, and the stepped surface of the enlarged diameter portion abuts against the stepped surface of the connecting portion. A forming step in which the most recessed portion of the inclined surface of the connecting portion of the extended portion of the enlarged diameter of the cylinder is crimped toward the axial side to form the crimped portion, A rotation step in which the cylinder is rotated about the axis relative to the connection portion of the housing, and the crimping portion is positioned at the other end of each of the inclined surfaces, A method for assembling a pretensioner, including [the part mentioned].

10. A pretensioner that activates in an emergency and increases the restraining force on the vehicle occupant by webbing by pulling in the retractable member, A wire, with one end connected to the member to be pulled in, A piston connected to the other end of the wire, A cylinder that slidably houses the piston, A gas generator supplies gas to a communication section connected to the cylinder to operate the piston in the direction of pulling in the wire, A housing that houses the aforementioned communication portion and connects the cylinder to a position that communicates with the aforementioned communication portion, The housing is provided with an insertion hole for guiding the wire to the communication portion, A wire guide is installed at the boundary between the insertion hole and the communication portion, sealing the boundary portion and allowing the wire to be inserted through a hole provided in the center, Equipped with, The wire guide has a first portion formed in the same shape as the inner circumferential surface of the communication portion, a second portion formed to be able to fit into the boundary portion, and a first engaging portion provided between the first portion and the second portion. Between the boundary portion and the communication portion of the housing, a second engaging portion is provided which engages with the first engaging portion when the wire guide is installed on the boundary portion. Pretensioner.

11. A seat belt device comprising a pretensioner according to any one of claims 1 to 8 or 10.

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