JP6764261B2 - Ignition with piston and pyroactuator - Google Patents

Description

The present invention relates to an igniter with a piston that operates a piston by utilizing a fireworks technology and a pyroactuator using the same. In particular, the present invention relates to a pyroactuator suitable for operating a vehicle safety device such as a seatbelt pretensioner device.

Various vehicle safety devices have been devised and installed in automobiles to protect occupants and pedestrians in the event of a car collision. For example, a seatbelt pretensioner device is a safety device for the purpose of winding up the slack of a seatbelt in the event of a vehicle collision and securely restraining a occupant. In addition, a bonnet lift device that lifts the bonnet in the event of a collision is installed in the bonnet hood as a device for protecting pedestrians. Many of these vehicle safety devices use pyroactuators to push out pins by the combustion pressure of explosives to activate the safety devices.
As the pyroactuator, for example, Patent Document 1 discloses a pyroactuator in which a piston having a piston rod is inserted inside a tubular housing to which an igniter is assembled. Patent Document 2 describes a pyroactuator in which an igniter and a piston are sandwiched between divided tubular casings and integrated with a sleeve. Further, Patent Document 3 describes a pyroactuator provided with a combustion chamber partitioned by an igniter and a thin film partition member, and the thin film partition member moves to push out a piston member.

Japanese Unexamined Patent Publication No. 2006-256396 Japanese Unexamined Patent Publication No. 2003-247509 US Patent US7,735,405B2

Since the pyroactuator for a vehicle safety device is a device that uses the combustion pressure of explosives, it is required to have a structure in which the generated pressure is efficiently applied to the piston. In addition, structural improvements related to miniaturization and weight reduction are required.
The present invention has been made to solve the above problems, and it is an object of the present invention to provide an igniter pyroactuator with a piston, which can efficiently apply the combustion pressure of the igniter to the piston and achieve miniaturization and weight reduction. And.

In the present invention, by assembling a piston and an igniter to form an integrated igniter with a piston, the combustion pressure of the igniter can be directly transmitted to the piston, pressure energy can be efficiently used, and the combustion chamber The present invention was completed with the idea that the capacity can be reduced and the number of parts can be reduced, and the size and weight of the piston actuator can be reduced. The gist of the present application is the following inventions [1] to [8].

[1] The ignition unit (5) including the resistance element (3) and the ignition agent (4) and the pair of conductive terminal pins (6) connected to the resistance element (3) are electrically insulated and held. An igniter (2) having an embolizer (7) and a piston (8) having a recess (9) having a columnar shape and one end of which is partitioned by a sleeve (10) are provided, and the recess (9) has the ignition portion. An igniter with a piston (5) in which the opening formed by the sleeve (10) of the recess (9) is sealed by the plug (7) to partition the combustion chamber (11). 1).
The present invention is an assembly of an igniter (2) and a piston (8), in which an igniter (4) is housed in a recess (9) of the piston (8) to form a combustion chamber (11). It is characterized by being. Normally, the igniter (2) is provided with a cup body containing the igniter (4) to partition the combustion chamber (11), but the present invention has no cup body and has a recess (9). The piston (8) has the function of a cup body and is installed by partitioning the combustion chamber (11), and further serves as a member having the function of the piston (8).
In the present invention, since the ignition portion (5) and the piston (8) are in direct contact with each other, the combustion pressure can be directly transmitted to the piston (8) and the piston (8) can be driven efficiently. .. Further, the capacity of the combustion chamber (11) can be reduced, the cup body for loading the igniting agent (4) which is normally used can be reduced, and the size and weight can be reduced and the cost can be reduced. ..

[2] A piston locking portion (12) is provided at the open end of the sleeve (10), and an embolizing locking portion (13) is provided at the sealing portion of the recess (9) of the embolizing (7). The igniter with a piston (1) according to the above [1], wherein the piston locking portion (12) and the embolic locking portion (13) are engaged.
[3] The piston locking portion (12) is an annular convex portion (12a), the embolic locking portion (13) is an annular groove portion (13a), and the annular convex portion (12a) and the annular groove portion ( The igniter with a piston (1) according to the above [2] to which 13a) is engaged.
The present invention preferably has a structure in which the igniter (2) and the piston (8) are engaged and integrated. By engaging and fixing the igniter (2) and the piston (8), the positioning of these members becomes easy. Further, in the case of an engaging structure having an uneven shape such as an annular convex portion (12a) and an annular groove portion (13a), it can be assembled by a simple snap-in operation, and the igniter (2) and the piston can be assembled with less resistance during operation. It is advantageous because the locking of (8) is released.

[4] The above [1] to [3], wherein the primary igniter (4a) is arranged in contact with the resistance element (3), and the secondary igniter (4b) is filled in the recess (9). The igniter with a piston (1) according to any one of the items.
In the present invention, in order to promote reliable ignition of the igniting agent (4), a primary igniting agent (4a) having excellent ignitability attached to the resistance element (3) and a secondary igniting agent (4a) for securing combustion pressure energy are used. It is preferable that the igniter (4b) is provided.

The present invention also includes a pyroactuator (14) using the piston-equipped igniter (1) according to the inventions [1] to [4].
[5] A pyroactuator (14) having a piston-equipped igniter (1) according to any one of the above [1] to [4] and a case (15) having both ends open, wherein the case ( A pyroactuator (14) in which a piston (8) is housed inside the cylinder of the case (15) and the embolus (7) is installed so as to close an opening at one end of the case (15).
[6] The pyroactuator (14) according to the above [5], wherein the outer peripheral diameter of the piston (8) is substantially the same as the inner diameter of the case (15).
The present invention is an igniter by assembling a case (15) forming a guide path for the piston (8) to move and an igniter (1) with a piston according to the inventions [1] to [4]. It is possible to provide a pyroactuator (14) that drives the piston (8) with the combustion pressure of (2). In a normal pyroactuator, since the igniter and the piston are composed of separate members, a special structure or mechanism for fixing the piston is required. However, in the present invention, since the piston (8) is fixed to the igniter (2), the case (15) constituting the pyroactuator may have a simple tubular structure. Therefore, the case (15) and the pyroactuator (14) including the case (15) can be made smaller and lighter.

[7] The piston (8) has a piston rod (8b) protruding from the other opening of the case (15), and covers the outer wall portion of the case (15) to cover the case (15). The resin housing (16) is coated so that the other opening side has a reduced diameter, and the resin housing (16) covers a part of the peripheral surface of the protruding portion of the piston rod (8b). 5] or the pyroactuator (14) according to [6].
It is preferable that the igniter (1) with a piston and the case (15) according to any one of the above [1] to [4] are assembled to form a resin housing (16) in which a mantle portion is further formed by a resin mold. .. That is, by using the resin housing (16) as the outer shell, it is possible to provide the pyroactuator (14) having excellent workability for assembling to the vehicle safety device (module). Further, the resin housing (16) covers the peripheral surface of the protruding portion of the piston rod (8b) to ensure the airtightness inside the resin housing (16) including the combustion chamber (11) of the pyroactuator (14). Can be done.

[8] A seatbelt pretensioner device using the pyroactuator (14) according to any one of the above [5] to [7].
The pyroactuator (14) of the present invention has a simple structure and can be reduced in weight, and when a resin housing (16) that is easy to mold is adopted, it is excellent in module assembly. By integrally molding the resin housing (16) with the module side, it is possible to reduce the number of parts and achieve ease of assembly.
The pyroactuator (14) of the present invention is preferably applied to the starting device of the seatbelt pretensioner device. In particular, it is preferable to use it as a starting device for a binding force adjusting mechanism (selectable force mitter) of a pretensioner device.

According to the present invention, since the ignition portion (5) of the igniter (2) and the piston (8) are arranged to be in direct contact with each other, an igniter with a piston (1) capable of efficiently transmitting combustion pressure to the piston is provided. can do. The igniter (1) with a piston can reduce the capacity of the combustion chamber (11) and the number of parts, and is compact, lightweight, and low cost. Therefore, the pyroactuator (14) using this is also small and lightweight and low cost.

It is a schematic cross-sectional view of the igniter (1) with a piston in the 1st Embodiment of this invention. It is a schematic cross-sectional view of the pyroactuator (14a) in the 2nd Embodiment of this invention. It is a schematic cross-sectional view of the pyroactuator (14b) in the 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1 is a cross-sectional view showing a first embodiment of an igniter with a piston (1a) according to the present invention.
The igniter (1a) with a piston according to the first embodiment shown in FIG. 1 is a pair of an ignition unit (5) including a resistance element (3) and an igniter (4) and a pair connected to the resistance element (3). It is provided with an igniter (2) having a plug (7) that electrically insulates and holds the conductive terminal pin (6), and a recess (9) that is columnar and has one end partitioned by a sleeve (10). The piston (8) is provided, the ignition portion (5) is contained in the recess (9), and the opening formed by the sleeve (10) of the recess (9) is locked by the plug (7). This is an igniter (1a) with a piston in which the combustion chamber (11) is partitioned.

The igniter (2) is a device that energizes a resistance element (3) by an electric signal to generate resistance heat and burns an igniter (4) to generate pressure energy. The igniter (2) is a pair of conductive elements electrically connected to the resistance element (3), an ignition unit (5) including an igniter (4) arranged around the resistance element (3), and the resistance element (3). It is composed of a terminal pin (6) and an embolus (7) that insulates and holds the terminal pin.

When the igniter (2) detects a vehicle collision, a predetermined amount of current flows through the resistance element (3) via the conductive terminal pin (6). As a result, the resistance element (3) generates Joule heat to ignite the ignition charge (4).
As the resistance element (3), a resistant conductive material that generates resistance heat when energized is used, and generally a nichrome wire, a resistance wire made of an alloy containing platinum and tungsten, or the like is used.
The time from when a current flows through the resistance element (3) until the igniter (2) operates is generally 2 milliseconds or less when a nichrome wire is used for the resistance element (3).

As the igniter (4) shown in FIG. 1, a primary igniter (4a) in a mode of contacting with the resistance element (3) and a secondary igniter (4b) loaded around the primary igniter (4a) are used. In order to efficiently transfer the Joule heat of the resistance element (3) to the igniter (4), it is preferable that the igniter (4) is attached to the resistance element (3) and solidified. Such an embodiment is advantageous because a chemical having a high ignition sensitivity can be used as the primary ignition agent (4a) and a chemical having a high gasification rate and good combustion efficiency can be used as the secondary ignition agent (4b). Is.

As the primary igniter (4a), a pyrotechnic composition containing a metal powder and an oxidizing agent and a binder agent is used. Examples of the metal powder include zirconium, zirconium hydride, aluminum, magnesium, magnalium, titanium, titanium hydride, iron, tungsten, boron and the like, and zirconium is more preferably used. The oxidizing agent contains one or more selected from the group consisting of nitrates, basic nitrates, metal oxides, metal hydroxides, and basic carbonates, and specifically contains basic zinc nitrate and bases. Examples thereof include sex cobalt nitrate, basic copper nitrate, copper oxide, copper nitrate, copper hydroxide, and basic copper carbonate. Examples of the binder agent include nitrocellulose, carboxymethyl cellulose, cellulose acetate, cellulose acetate butyrate, byton rubber, GAP (Glysidyl Azide Polymer), polyvinyl acetate, silicone-based binder and the like.

When manufacturing the igniter (2) using the primary igniter (4a), for example, the composition of the primary igniter (4a) is first made into a slurry, and the slurry is dipped into the resistance element (3) a predetermined number of times. It can be manufactured by the operation of drying and solidifying.
A solvent is preferably used for preparing the slurry of the primary igniter (4a) composition, and the solvent is, for example, an acetate solvent such as ethyl acetate, isoamyl acetate or isobutyl acetate or a ketone such as acetone, methyl ethyl ketone or methyl butyl ketone. A solvent can be used. The amount to be used may be appropriately selected so as to form a slurry suitable for dipping, but is usually 50 to 150 parts by mass, preferably 80 to 120 parts by mass with respect to 100 parts by mass of the primary igniter (4a) composition. It is a department.

The secondary igniter (4b) is ignited by heat particles generated by ignition and combustion of the primary igniter (4a) to generate combustion gas and heat to generate pressure energy. The secondary igniter (4b) is generally formed as a molded product containing a fuel, an oxidant and any additive.
The fuel includes, for example, a triazole derivative, a tetrazole derivative, an azodicarboxylic amide derivative, a hydrazine derivative, a metal hydride, a metal powder, or the like, and preferably two or more of these are used in combination. Specifically, nitroguanidine, guanidine nitrate, cyanoguanidine, 5-aminotetrazole, zirconium hydride, titanium hydride, zirconium powder, tungsten powder, molybdenum powder and the like are preferably used.
Examples of the oxidizing agent include alkali metals, alkaline earth metals, transition metals, ammonium nitrates, basic nitrates, metal oxides, metal hydroxides, basic carbonates, perchlorates, and chlorates. .. Specifically, basic zinc nitrate, basic cobalt nitrate, basic copper nitrate, copper oxide, copper nitrate, copper hydroxide, basic copper carbonate, potassium perchlorate, sodium perchlorate, potassium chlorate, chlorine. Examples include sodium acid nitrate.
Optional additives include binders, slag-forming agents, combustion modifiers and the like. For these, additives usually used as the ignition agent (4) may be used.
The secondary igniter (4b) is prepared by mixing a fuel, an oxidant and an optional additive and molding the mixture. As the molded body, a powdery body, a granular body, a granular body or the like is used. It is preferable to use it in a granular molded product in which the secondary igniter (4b) component is uniformly mixed.
The secondary igniter (4b) is loaded with the required amount of pressure energy required to drive the vehicle safety device by pushing out the piston (8) described later. The loading amount is appropriately set according to the required pressure energy.

The embolus (7) in the igniter (2) is a substantially cylindrical member that insulates and holds the conductive terminal pin (6). The embolus (7) shown in FIG. 1 has a stepped columnar shape in which the central portion of the columnar side surface is enlarged, and is the first tubular end portion on the resistance element (3) side and the opposite side thereof. , Has a second cylindrical end with a protruding connector terminal side of the conductive terminal pin (6).
The embedding (7) is preferably a resin that is insulating and easy to mold, and is a thermosetting resin such as an epoxy resin, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), nylon 6 (PA6), nylon 66. It is preferably molded into an arbitrary shape using a thermoplastic resin typified by (PA66), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), a fluororesin, or the like. When these resins are selected as raw materials, they may be formed of a resin material containing a filler such as glass fiber (reinforcing material) in order to secure the mechanical strength of the embolus (7) after molding.
The embolus (7) shown in FIG. 1 has a piston (8) described later on the side wall surface of the first tubular end portion from which the conductive terminal pin (6) in the connection direction of the resistance element (3) protrudes. It is provided with an annular groove portion (13a) corresponding to an embolic locking portion (13) for locking.

A columnar piston (8) is arranged in contact with the surface of the igniter (2) on which the resistance element (3) and the ignition portion (5) including the igniter (4) are arranged. The piston (8) has a hole-shaped recess (9) in which one end of the columnar column is partitioned by a sleeve (10), and the open end face of the recess (9) is in contact with the igniter (2). It accommodates the ignition unit (5). Then, the sleeve (10) is brought into contact with the first tubular end surface of the embolus (7), sealed and arranged, and sealed with the recess (9) including the sleeve (10) and the embolus (7). A combustion chamber (11) for burning the igniter (4) to generate pressure energy is formed by the space partitioned by stopping.
The recess (9) has a capacity sufficient to accommodate the ignition portion (5) and a capacity to be loaded with a sufficient amount of the igniting agent (4) capable of obtaining sufficient combustion pressure energy. The capacity of the recess (9) is arbitrarily set according to the required performance for driving the module of the pyroactuator (14a).
A feature of the present invention is that there is no cup member for loading the igniter (4) used in the ordinary igniter (2). That is, the piston (8) in which the recess (9) is formed also serves as a cup member for loading the ignition charge. Since the piston (8) is arranged to be in direct contact with the ignition portion (5), it can directly receive the combustion pressure energy of the ignition charge (4), suppress the pressure loss, and drive the piston efficiently. It is advantageous from. Further, since it becomes possible to load a larger capacity ignition charge (4) than the normal ignition charge loading cup body, it can be used for driving various actuators.

The piston (8) is preferably formed of a resin material having excellent moldability, for example, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), nylon 6 (PA6), nylon 66 (PA66), polyphenylene sulfide (PPS). ), Polyphenylene oxide (PPO), fluororesin and other resins are preferable. It is more preferable to form the resin material containing glass fiber as a reinforcing material in order to improve the mechanical strength.

The piston (8) has an annular convex portion (12a) formed as a piston locking portion (12) on the contact surface of the first tubular end portion of the piston (8) on the open end surface of the sleeve (10). .. The annular tubular portion (12a) is arranged to abut the annular groove portion (13a) which is the embolic locking portion (13), and these are engaged with each other to engage the igniter (2) and the piston (8). ) Is fixed.
The annular convex portion (12a) may be arranged so that it can be engaged and locked with the annular groove portion (13a), and preferably the igniter (2) and the piston (8) are engaged by a snap-in method. It is preferable that the design is adjusted so as to have a locking relationship suitable for stopping and assembling.

Further, the outer peripheral portion corresponding to the sleeve (10) position of the long columnar piston (8) has a stepped portion and has a shape reduced in diameter toward the center of the shaft. That is, the outer diameter of the sleeve (10) portion is smaller than the outer diameter of the piston (8). With such a structure, the flexibility of the sleeve (10) portion can be obtained, and the engagement assembly operation by snap-in becomes easy. At the same time, when the igniter (4) ignites and a sufficient amount of pressure energy is generated in the combustion chamber (11), the flexible region of the sleeve (10) portion is secured, and the piston locking portion (12) and By disengaging the engaged state of the plug locking portion (13), the piston (8) can be opened and brought into a movable state. The reduced diameter structure of the sleeve (10) is not an essential configuration in the present invention, and the fixing of the piston (8) is released by adopting a mode in which the locking structure portion is detached or broken by the combustion pressure energy. The mode may be such that the state is reached.

An extending columnar piston rod (8b) formed integrally with the piston (8) is provided at the other end of the piston (8) on the opposite side where the recess (9) is arranged. The piston rod (8b) is a tubular body extending axially from the piston (8), and has an outer peripheral diameter equal to or smaller than the outer peripheral diameter of the piston (8). The tip of the piston rod (8b) is an acting member that protrudes when the igniter (2) is activated and the piston (8) moves to a state of extending in the axial direction. That is, the piston-equipped igniter (1a) can be used as a device for driving a target module such as a vehicle safety device by pushing out the piston rod (8b) by the combustion pressure energy of the igniter (2). it can.

Next, the operation of the igniter with a piston (1a) according to FIG. 1 will be described.
When an electric signal is sent from the accident sensor mounted on the automobile to the igniter (2), the resistance element (3) of the ignition unit (5) generates heat by energization and the igniter (4) ignites. Due to the combustion pressure energy generated by this, the engaging structure of the piston locking portion (12) and the embolus locking portion (13) is disengaged or broken to open the piston (8), which moves in the axial direction. The piston rod (8b) is projected. When the piston rod (8b) is pushed out, it becomes an action site for driving a target module such as a vehicle safety device.

In the igniter with a piston (1a) shown in FIG. 1, the piston locking portion (12) is an annular convex portion (12a), and the embolic locking portion (13) is engaged with the annular groove portion (13a). Although the shape is shown, the engagement relationship may be the opposite. That is, the piston locking portion (12) may be an annular groove portion (13b), and the embolic locking portion (13) may be an annular convex portion (12b) in which they are engaged. It is preferable that the igniter (2) and the piston (8) are adjusted and designed so as to have a locking relationship suitable for being locked and assembled by a snap-in method. The piston locking portion (12) and the embolic locking portion (13) may be engaged with each other via an adhesive or a sealing material.

Further, the igniter with a piston (1a) shown in FIG. 1 is an igniter (2) in which a conductive terminal pin (6) is fixed by a plug with an insulating resin, but the present invention is limited to this embodiment. Rather, each conductive terminal pin uses a cylindrical metal holding member via an insulating sealing member made of a glass material or a resin material, and this is a resin-molded plug with a thermoplastic resin or the like. May be used. When such an igniter is used, the resistance element and the conductive terminal pin may be directly connected or may be connected via the metal holding member.
In this case, the recess of the piston may be locked by the metal holding member, or may be sealed by a resin mold. When the piston and the igniter are engaged and fixed, the embolic locking portion arranged on the igniter side may be formed on the metal holding member, or may be formed on the resin mold portion. Is also good. The embolic locking portion may have an annular groove shape, or conversely, an annular convex portion shape. As a matter of course, the piston locking portion that comes into contact with the embolic locking portion has a corresponding concave-convex locking portion to engage with the piston locking portion.

The igniter (1) with a piston shown in FIG. 1 can be manufactured by the following manufacturing process.
(Step 1) It has an embolus (7) that insulates and holds a pair of conductive terminal pins (6a) conducted by the resistance element (3), and the primary ignition agent (4a) holds the resistance element (3). A step of preparing an igniter (2) having an igniter (5) attached so as to cover it.
(Step 2) A step of loading a secondary igniter (4b) into the recess (9) of a piston (8) having a recess (9) partitioned by a sleeve (10).
(Step 3) A step of inserting the ignition portion (5) to which the primary igniter (4a) is attached into the recess (9) loaded with the secondary igniter (4b).
(Step 4) A step of assembling an igniter (1) with a piston by engaging the embolization locking portion (13) of the embolization (7) of the igniter (2) with the piston locking portion (12) of the piston (8). ..
The igniter (1) with a piston of the present invention can be easily manufactured by engaging and assembling the piston (8) portion and the igniter (2) portion by a snap-in process. That is, since the installation of the igniter (4) and the assembly of the piston (8) in the igniter (2) can be achieved by one step of the snap-in, the manufacturing process is simple, short and extremely advantageous.

Next, the pyroactuator (14) of the present invention will be described.
The present invention also includes a pyroactuator (14) using the piston-equipped igniter (1). That is, the igniter (1) with a piston is housed in a case (15) having both ends open, and one end opening of the case (15) is closed by an embolus (7) of the igniter (2). By installing it, the pyroactuator (14) can be provided. At this time, it is necessary that the end of the piston (8) or the piston rod (8b) protrudes from the open end of the case (15) when the igniter (1) with a piston operates. That is, the pyroactuator (14) is an activation device for operating a module mechanism such as a vehicle safety device by projecting a piston (8) or a piston rod (8b) when the igniter (2) is operated.
Since the pyroactuator (14a) of the present invention uses a member in which the piston (8) and the igniter (2) are already combined, it is only necessary to fix the igniter (2) using the case (15). The housing shape for forming the outer shell can be simplified, the number of parts can be reduced, and the manufacturing process can be simplified.
The pyroactuator (14) according to the present invention will be described below with reference to specific examples.

<Second Embodiment>
FIG. 2 is a cross-sectional view showing a pyroactuator (14a) using a piston-equipped igniter (1a) assembly according to a second embodiment of the present invention.
The pyroactuator (14a) shown in FIG. 2 includes a tubular housing composed of a tubular case (15) having both ends open and a resin housing (16), and the igniter with a piston (1a) shown in FIG. Is an inherent pyroactuator (14a).
The pyroactuator (14a) is intended by moving the piston (8) in the axial direction of the case (15) and pushing out the piston rod (8b) by the combustion pressure energy generated by the operation of the igniter (2). It is a device that drives a module such as a vehicle safety device.

In the pyroactuator (14a) according to FIG. 2, the igniter with a piston (1a) has the same meaning as described above.

The case (15) has a tubular shape with both ends open, and one opening is closed by the igniter (2). That is, the opening of the case (15) and the embolus (7) of the igniter (2) are in contact with each other. The ignition portion (5) of the igniter (2) and the piston (8) are arranged inside the tubular shape of the case (15).
The case (15) is preferably cylindrical, but is not particularly limited, and may be a polygonal cylinder such as an elliptical cylinder or a quadrangular cylinder.

The tubular case (15) is a material selected from materials such as aluminum, iron, copper, steel, alloys thereof, and resin, and is formed by forging, pressing, drawing, molding, or the like. .. For the case (15), it is preferable to use a molded product made of an iron-based metal material such as iron or stainless steel for the purpose of ensuring the heat resistance and pressure resistance of the combustion chamber. Further, the case (15) preferably has a tubular shape having a relatively thin thickness for the purpose of reducing the weight of the pyroactuator. When the resin housing (16) described later is formed by injection molding, the thickness of the case (15) is preferably such that the strength to withstand the pressure of the resin at the time of injection is secured.

Inside the case (15), a piston (8) that can move in the axial direction of the tubular case is arranged. The outer diameter of the piston (8) is about the same as or slightly smaller than the inner diameter of the case (15), and the inside of the case (15) can be moved in the axial direction. Therefore, the outer peripheral surface of the piston (8) may slide in contact with the inner peripheral surface of the case (15), or between the outer peripheral surface of the piston (8) and the inner peripheral surface of the case (15). It may move with a slight gap. A lubricant may be interposed between the outer peripheral surface of the piston (8) and the case (15) for smooth movement of the piston (8). For the purpose of use of the pyroactuator (14a), the piston (8) moves only once, and there is no problem even if it slides.
The piston (8) has a transverse shape in contact with the inner wall of the case (15), and if the case (15) has a cylindrical shape, it preferably has a circular transverse shape corresponding to the cylindrical shape.
The outer peripheral portion of the piston corresponding to the sleeve (10) position of the piston (8) has a stepped portion and has a reduced diameter toward the center of the shaft, and the outer peripheral portion of the case (15) and the sleeve (10). A gap is formed in. This gap is the sleeve flexible region space (20), and when the igniter (4) ignites and a sufficient amount of combustion pressure energy is generated in the combustion chamber (11), the sleeve (10) receives the pressure. The piston (8) is released by the disengagement of the piston locking portion (12) and the plugging locking portion (13) from the engaged state by flexing to the case (15) side to bring the piston (8) into a movable state. Can be done.

The pyroactuator (14a) illustrated in FIG. 2 has a reduced diameter opening (18) in which the other opening of the case (15) is provided with a shoulder portion (17). Then, the reduced diameter opening (18) is closed and protrudes by the piston rod (8b). The range of motion of the piston (8) is defined by the other opening of the case (15) having a reduced diameter shape as described above.
The outer diameter of the piston rod (8b) is smaller than the outer diameter of the piston (8), and is about the same as or slightly smaller than the diameter of the reduced diameter opening (18) of the case (15). Therefore, the outer peripheral surface of the piston rod (8b) may slide in contact with the reduced diameter opening (18), or between the outer peripheral surface of the piston rod (8b) and the reduced diameter opening (18). It may move in the presence of a slight gap. In this case, a lubricant may be interposed between the outer peripheral surface of the piston rod (8b) and the diameter reduction opening (18).

In the pyroactuator (14a) according to the present invention, a mantle portion is formed by a resin housing (16). That is, the resin housing (16) covers the embolus (7) of the igniter (2) and the outer wall portion of the case (15), and the piston rod (8b) of the case (15). The protrusion side and the opening side are covered so as to reduce the diameter. That is, in the pyroactuator (14a) of the present invention, the tubular housing is formed of a composite material consisting of two types of members, a tubular case (15) and a resin housing (16). With this structure, the slidability of the internal piston and the strength resistance to heat and pressure at the time of ignition can be maintained.
For the resin housing (16), for example, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), nylon 6 (PA6), nylon 66 (PA66), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), fluororesin and the like are used. Is preferable. Further, it is preferable to form the resin material from a resin material containing a reinforcing material such as glass fiber. As the material of the resin housing (16), it is preferable to use the same material as that of the piston rod (8b).

The pyroactuator (14a) shown in FIG. 2 has a shape in which the case (15) is provided with a shoulder portion (17) and has a reduced diameter opening (18), and the resin housing (16) is the same. It is molded in a shape that reduces the diameter so as to cover the shoulder portion (17) and the reduced diameter opening (18). By forming the case (15) into a shape provided with such a reduced diameter opening (18), it is possible to cover the case (15) with the resin housing (16) including the outer surface portion, and further to the inner piston (8). Sliding property and strength resistance at the time of ignition can be maintained. Further, the resin housing (16) can be integrally molded by the injection molding method including the tubular side surface portion of the case (15) and the portion covering the other opening, which is advantageous in the manufacturing process. Have.

Further, the resin housing (16) has a shape covered over the conductive terminal pin (6) side of the embolus (7) of the igniter (2). With such a shape, the tubular case (15) containing the igniter with a piston (1a) can be integrated with the resin housing (16). The resin housing is also molded with a connector insertion hole (19) for attaching a connector for electrically connecting to the conductive terminal pin (6). The connector insertion hole (19) requires a locking groove for locking the connector, but the resin housing (16) has excellent processability and can be easily manufactured.
The resin housing (16) is integrally molded by injection molding from the reduced diameter opening (18) of the case (15) to the embolus (7) and the connector insertion hole (19) of the igniter (2). In addition to having an advantage in the manufacturing process, the heat resistance and pressure resistance are further improved.

The pyroactuator (14a) shown in FIG. 2 preferably has a contact portion (21) that is in contact with and covers the outer peripheral surface of the protrusion portion of the resin housing (16) and the piston rod (8b). .. With such a structure, in the pyroactuator (14a), the airtightness inside the ignition portion (5) loaded with the ignition agent (4), which may deteriorate in performance due to moisture absorption, can be ensured.
The contact portion (21) needs to be grounded to such an extent that it does not interfere with the driving of the piston rod (8b) when the pyroactuator (14a) is operated. For example, when the resin housing (16) is injection-molded, the resin of the resin housing (16) and the resin of the piston rod (8b) may be melted and fixed to each other to maintain airtightness and then be formed. Therefore, it is preferable to use the same material for the resin housing (16) and the piston rod (8b). Further, an appropriate sealing material such as an O-ring member such as fluororubber, styrene rubber, or olefin rubber may be used for the contact portion (21). As another embodiment, a method of applying an adhesive to the contact portion (21) to seal the contact portion (21) may be used. For example, an adhesive containing a cyanoacrylate resin, a silicone resin, a styrene rubber, an olefin rubber or the like as a raw material can be preferably used.
By providing the contact portion (21) and ensuring the airtightness inside the case (15) including the combustion chamber (11), for example, an igniter (2) having low airtightness can be applied. It is an advantageous structure in terms of points.

<Third Embodiment>
FIG. 3 is a cross-sectional view showing a pyroactuator (14b) using an igniter with a piston (1b) according to a third embodiment of the present invention. Since it has almost the same structure as the pyroactuator (14a) according to FIG. 2, only the different parts will be described. The same number as in FIG. 2 means that they are the same.

The pyroactuator (14b) shown in FIG. 3 uses a piston-equipped igniter (1b) in which a reduced diameter portion is not installed in a portion corresponding to the sleeve (10) of the piston (8). It is different from the actuator (14a). As a result, it has a tubular case (15) shape with both ends open, and the outer peripheral diameter of the outer peripheral portion corresponding to the sleeve (10) position of the piston (8) is the same as the outer peripheral diameter of the piston (8). One opening is closed by the igniter (2), and no gap space is set between the outer peripheral portion corresponding to the sleeve (10) position of the piston (8) and the case (15). It is in close contact. By adopting a structure without this gap, when the ignition charge (4) is ignited and a sufficient amount of combustion pressure energy is generated in the combustion chamber (11), the sleeve (10) receives the pressure and the piston locking portion. By breaking and disengaging the engaging portion of (12) and the plugging locking portion (13), the piston (8) can be opened and brought into a movable state.

The pyroactuator (14) of the present invention has a simple structure that suppresses pressure loss, maintains the slidability of the piston (8) and strength resistance at the time of ignition, and has a strong shape together with the resin housing (16). Can be kept. Therefore, it can be applied to the activation device of the seat belt pretensioner device. In particular, it is preferable to use it as a starting device for a binding force adjusting mechanism (selectable force mitter) of a pretensioner device.

The pyroactuator (14) of the present invention can be manufactured by the following manufacturing process.
(Step 1) The above-mentioned igniter (1) with a piston is prepared, and the tubular case (15) containing the piston (8) and the igniter (2) are brought into contact with each other to open one opening of the case. Blocked case (15) -Step to obtain igniter with piston (1).
(Step 2) Case (15) -Piston-equipped igniter (1) is placed in a housing molding mold, and molten resin is injected into the embolic portion (7) of the igniter (2) and the outer wall portion of the case (15). A step of forming a resin housing (16) by injection molding, which is coated over and coated so that the other opening side of the case (15) is reduced in diameter.
That is, the pyroactuator (14) of the present invention can have an advantage that the resin housing (16) can be injection-molded, and a manufacturing method advantageous in processing molding can be adopted. That is, by using the injection molding method, the pyroactuator (14) can be easily molded into various shapes, so that the module can be assembled easily. Further, the resin housing (16) can be integrally molded with the module side, so that the number of parts can be reduced and the ease of assembly can be achieved.

Next, the operation of the pyroactuator (14) according to the present invention will be described.
When an electric signal is sent from the accident sensor mounted on the automobile to the igniter (2), the igniter (4) contained in the ignition unit (5) is ignited. Due to the combustion pressure energy generated by this, the seal between the sleeve (10) of the igniter (2) and the piston (8) is released, the piston (8) moves in the axial direction, and the piston rod (8b) is reduced in diameter. It protrudes from the opening (18). The movement of the piston rod (8b) is stopped when the piston (8) and the shoulder portion (17) of the case (15) are in contact with each other.
In such an operation process, the combustion chamber (11) partitioned by the igniter (2) and the case (15) exposed to a high-temperature and high-pressure environment is formed with a composite material composed of a resin housing (16) and a case (15). By doing so, the case (15) can maintain the slidability of the piston (8) and the strength resistance at the time of ignition, and can maintain a strong shape together with the resin housing (16). Further, by using the resin housing (16), the weight reduction of the pyroactuator (14) can be achieved. Further, the resin housing (16) covers the plug (7) of the igniter (2), the case (15), the shoulder portion (17), and the reduced diameter opening (18), and the piston rod ( By covering the coating on the peripheral surface of the protruding portion of 8b) with injection molding, each member can be integrated. In particular, the peripheral surface of the protruding portion of the piston rod (8b), the resin housing (16), and the igniter (2). By melting the resin interfaces of the body and the resin housing (16) with each other, the weight is reduced with a simple structure and the airtightness inside the ignition part (5) is ensured, and the piston actuator (14) has excellent environmental resistance. ) Can be provided.

1a, 1b: igniter with piston, 2: igniter, 3: resistance element, 4a: primary igniter, 4b: secondary igniter, 5: ignition part, 6: conductive terminal pin, 7: plug, 8: Piston, 8b: Piston rod, 9: Concave, 10: Sleeve, 11: Combustion chamber, 12a: Annular convex part, 13a: Circular groove part,
14a, 14b: Pyroactuator, 15: Case, 16: Resin housing, 17: Shoulder, 18: Reduced diameter opening, 19: Connector insertion hole, 20: Sleeve flexible area space, 21: Contact part

Claims (7)

An embolus (7) that electrically insulates and holds a pair of conductive terminal pins (6) connected to the resistance element (3) and the ignition portion (5) containing the resistance element (3) and the ignition agent (4). ), And an igniter (2)
A piston (8) with a columnar recess (9) having one end partitioned by a sleeve (10).
An opening formed by a sleeve (10) of the recess (9) in which the ignition portion (5) is inherent in the recess (9) and the piston (8) and the ignition portion (5) are in direct contact with each other. The portion is sealed with the embolus (7) to partition the combustion chamber (11) .
The piston has a piston locking portion (12) at the open end of the sleeve (10), and has an embolizing locking portion (13) at the sealing portion of the recess (9) of the embolizing (7). An igniter (1) with a piston in which the locking portion (12) and the embolic locking portion (13) are engaged. The piston locking portion (12) is an annular convex portion (12a), the embolic locking portion (13) is an annular groove portion (13a), and the annular convex portion (12a) and the annular groove portion (13a) are It engaged piston with igniter according to claim 1 (1). The igniter with a piston according to claim 1 or 2 , wherein the primary igniter (4a) is arranged in contact with the resistance element (3), and the secondary igniter (4b) is filled in the recess (9). (1). The igniter with a piston (1) according to any one of claims 1 to 3 .
A pyroactuator (14) having a case (15) with both ends open.
A pyroactuator (14) in which a piston (8) is housed inside the cylinder of the case (15) and the embolus (7) is installed so as to close one end opening of the case (15). The pyroactuator (14) according to claim 4 , wherein the outer peripheral diameter of the piston (8) is substantially the same as the inner diameter of the case (15). The piston (8) has a piston rod (8b) protruding from the other opening of the case (15).
It has a resin housing (16) that covers the outer wall portion of the case (15) and is coated so that the other opening side of the case (15) has a reduced diameter.
The pyroactuator according to claim 4 or 5 , wherein the resin housing (16) covers a part of the peripheral surface of the protruding portion of the piston rod (8b). A seatbelt pretensioner device using the pyroactuator (14) according to any one of claims 4 to 6 .

Images