Actuator

An actuator includes: a gas generator which generates an operation gas when actuated; an accommodation-side portion which accommodates and holds the gas generator; and a push-side portion which is pushed by the operation gas generated from the gas generator to advance relatively so as to move away from the accommodation-side portion, wherein: a seal material which realizes watertightness between the push-side portion and the accommodation-side portion before actuation is provided in an external surface side portion between the push-side portion and the accommodation-side portion by being poured and set through molding; and the seal material doubles as an adhesive which enables the push-side portion to move relatively when actuated and which provides a joining force with which the push-side portion can be restricted from moving relatively before actuation so as to join the push-side portion and the accommodation-side portion together.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2014-217637, filed on Oct. 24, 2014, the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Field of the Invention

The present invention relates to an actuator which starts an operation of a device to which it is attached by generating an operation gas which is a combustion gas when activated and more particularly to, for example, an actuator which is preferably used for an onboard automotive safety apparatus such as a hood pop-up apparatus which lifts up a hood panel in receiving a pedestrian as a protection target.

2. Description of the Related Art

Some of conventional actuators like the one described above are used in a hood pop-up device which lifts up a hood panel, and those actuators are configured as a piston-cylinder type actuator which makes use of combustion gas generated as a result of ignition of explosive material when a gas generator is activated as operation gas (for example, refer to JP-A-2011-208738). In this actuator, the piston rod includes the piston portion which can slide within the cylinder and the rod portion which extends to the outside of the cylinder from the piston portion and which supports a hood panel as a receiving member which receives a pedestrian as a protection target in such a way as to raise the hood panel as high as a pedestrian receiving position. Further, due to the actuator being disposed in the hood panel, in this actuator, the packing is provided in the gap portion defined between near the distal end of the rod portion of the piston rod and the inner circumferential surface of the cylinder with a view to preventing the intrusion of rain water into the interior of the actuator. In case rain water arrives at the gas generator which supplies the operation gas to the piston portion side, the ignition fails when the gas generator is activated, and therefore, the provision of the packing is necessary with a view to ensuring the waterproofness of the actuator.

Further, in this actuator, the E ring is provided in the rod portion with a view to preventing the unintentional protrusion of the piston rod before actuation, that is, the unintentional extension of the actuator which is triggered by the forward movement of the piston rod before actuation. This E ring is brought into abutment with the ceiling wall portion of the cylinder to prevent the forward movement of the piston rod when in actuation while striking strongly the ceiling wall portion to be dislocated from the rod portion to allow the forward movement of the piston rod when the actuator is actuated.

In the conventional actuator, however, since the packing is provided, the packing has to be selected while considering the production tolerance in dimension, and the packing accommodation groove has to be designed accordingly. In addition, the E ring and the E ring accommodation groove also need to be provided, resulting in the problem that the actuator cannot be configured simple.

SUMMARY

The invention has been made to solve the problem, and an object thereof is to provide an actuator which can ensure the waterproofness and the prevention of the extension thereof before actuation with a simple and easy configuration, even in the event that a gas generator is used which generates operation gas when actuated.

According to an aspect of the invention, there is provided an actuator including: a gas generator which generates an operation gas when actuated; an accommodation-side portion which accommodates and holds the gas generator; and a push-side portion which is pushed by the operation gas generated from the gas generator to advance relatively so as to move away from the accommodation-side portion, wherein: a seal material which realizes watertightness between the push-side portion and the accommodation-side portion before actuation is provided in an external surface side portion between the push-side portion and the accommodation-side portion by being poured and set through molding; and the seal material doubles as an adhesive which enables the push-side portion to move relatively when actuated and which provides a joining force with which the push-side portion can be restricted from moving relatively before actuation so as to join the push-side portion and the accommodation-side portion together.

In the actuator according to the invention, since the seal material which doubles as the adhesive closes the gap (the seal portion) between the push-side portion and the accommodation-side portion, the intrusion of rain water into the gas generator can be prevented to thereby ensure the waterproofness of the actuator before actuation. In addition, before actuation, the seal material which doubles as the adhesive joins the push-side portion and the accommodation-side portion together at the seal portion, whereby the push-side portion can be restricted from advancing relative to the accommodation-side portion, and the extension of the actuator before actuation can be prevented. Additionally, since the seal material which doubles as the adhesive joins the push-side portion and the accommodation-side portion together with the joining force which enables the push-side portion to move relative to the accommodation-side portion when actuated, the push-side portion releases the adhesion to move smoothly relative to the accommodation-side portion at the time of actuation of the actuator where the operation gas is generated from the gas generator.

In the actuator according to the invention, the seal material which doubles as the adhesive is provided by being poured and set through molding, and the seal material can easily be provided by being poured to fill the seal portion which is disposed on the external surface of the actuator. Further, in the actuator according to the invention, although the mold and the filling machine are needed, the conventionally required labor-hours to design to provide the packing, the packing accommodation groove, the E ring and the E ring accommodation groove or to assemble them together are unnecessary, and therefore, the actuator can be formed in a simple and easy fashion.

Consequently, in the actuator according to the invention, although the configuration is adopted in which the gas generator is used which generates the operation gas when actuated, the waterproofness and the prevention of the extension of the actuator before actuation can be ensured in a simple and easy fashion.

In the actuator according to the invention, the accommodation-side portion may include an input member for inputting an operation signal for the gas generator which is provided to project from the accommodation-side portion to an exterior portion, and a seal material formed from the same material as that of the seal material may be provided by being poured and set in the portion of the accommodation-side portion where the input member projects.

In the configuration like this, in pouring the seal material to fill the gap defined between the push-side portion and the accommodation-side portion, the seal material can simultaneously be poured to fill the space around the circumference of the input member in the accommodation-side portion. Because of this, in the configuration like this, the stable waterproofness of the whole of the actuator including the waterproofness around the circumference of the input member can easily be ensured.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an embodiment of the invention will be described based on drawings. As shown inFIGS. 1 to 3, an actuator21of a first embodiment is used in a hood pop-up apparatus (hereinafter, also referred to as a “pop-up apparatus” as required) U as an automotive safety apparatus and is provided in a hinge mechanism11near a rear end10cof a hood panel10of a vehicle V.

In this specification, unless described otherwise, front-to-rear and up-to-down directions coincide with front-to-rear and up-to-down directions of the vehicle V (refer toFIG. 1), and a left-to-right direction coincides with a left-to-right direction of the vehicle V when looking at the front of the vehicle V from the inside thereof.

In the case of the first embodiment, sensors6are provided in a front bumper5of the vehicle V as shown inFIG. 1to detect or predict a collision with a pedestrian, and signals from the sensors6are inputted into a control circuit, not shown. When the control unit detects a collision of the vehicle V with a pedestrian based on the signals from the sensors6, the control unit activates the actuator21by igniting gunpowder, not shown, in a gas generator70in the actuator21to generate an operation gas G to thereby actuate the pop-up apparatus U (refer toFIGS. 3, 8).

As shown inFIGS. 1, 2, the hood panel10is provided so as to cover an engine compartment ER of the vehicle V from thereabove. The hood panel10is connected to a body1of the vehicle V so as to be opened and closed at a front thereof by the hinge mechanism11which are disposed near the rear end10con both left and right edges10d,10e. The hood panel10is made of a metallic panel of steel or aluminum alloy and is made up of an upper outer panel10aand a lower inner panel10bwhose strength is enhanced higher than that of the outer panel10a. The hood panel10can plastically be deformed so as to absorb the kinetic energy of a pedestrian when it receives the pedestrian. In this embodiment, on a collision of the vehicle V with a pedestrian, the actuators21are actuated to create a deformation space S between the rear end10cof the raised hood panel10and the engine compartment ER as shown inFIG. 3, whereby an amount of plastic deformation when the hood panel10is bent to be deformed plastically can be increased, allowing the hood panel10to absorb greatly the kinetic energy of the pedestrian.

The hinge mechanisms11are provided near the rear end10con the left edge10dand the right edge10eof the hood panel10. The hinge mechanisms11each include a hinge base12which is fixed to the body1in a position lying below the rear end10cof the hood panel10, a mounting plate15which is disposed on a lower surface side of the rear end10cof the hood panel10, and a hinge arm14which is pivoted on the hinge base12and the mounting plate15. To describe in detail, the hinge base12is fixed to a mounting flange2awhich is connected to a hood ridge reinforcement2provided on the body1. When the hood panel10is opened in a normal use, the hinge mechanism11is designed to be opened about a pivot portion near a proximal end14aof the hinge arm14which lies at an end thereof which faces the hinge base12as a rotation center (refer to chain double-dashed lines inFIG. 2).

This hinge arm14is provided so as to extend forwards from the proximal end14ato a distal end14b. The proximal end14ais connected to a rear end portion of the hinge base12by making use of a support shaft13, and thus, the hinge arm14can rotate about the support shaft13as a rotation center. The distal end14bis also connected to a front end portion of the mounting plate15by making use of a support shaft16, and the hinge arm14can also rotate about the support shaft16as a rotation center. The left and right support shafts13,16are provided so that their axial directions follow the left-to-right direction of the vehicle V. However, in the normal use, the actuator21which is connected to connecting portions14c,15awhere the actuator21is connected to the hinge arm14and the mounting plate15is prevented from extension by means of a seal material81which doubles as an adhesive, which will be described later. Therefore, the hinge arm14does not rotate relative to the mounting plate15. Because of this, when it is opened and closed in the normal use, the hood panel10is opened and closed about the portions where the support shafts13are provided as the rotation centers. Namely, when opening the hood panel10, as shown by solid lines and the chain double-dashed lines inFIG. 2, a front end10fside of the hood panel10is raised together with the distal end14bsides of the hinge arms14about the left and right support shafts13as the rotation centers, whereby the hood panel10can be opened at the front thereof. Then, when the front end10fside of the hood panel10is pressed down, the hood panel10rotates about the support shafts13as the rotation center to be closed.

The left and right hinge mechanisms11are provided laterally symmetrical, and both ends (connecting portions25,62) of the actuator21are connected to the connecting portions14c,15a, respectively, where the actuator21is connected to the hinge arm14and the mounting plate15on a side facing the engine compartment ER, The connecting portion14cof the hinge arm14with the actuator21is disposed closer to the distal end14bside than an intermediate portion between the proximal end14aand the distal end14b. The connecting portion15aof the mounting plate15with the actuator21is disposed further rearwards than the support shaft16.

A known hood lock mechanism8is provided on the front end10fside of the hood panel10. The hood lock mechanism8includes a lock striker8awhich is fixed to a lower surface of the front end10fof the hood panel10and latch8bwhich is provided on the body1side to lock the striker8a. The latch8bis designed not to release the locking of the lock striker8auntil a lever, not shown, is operated. Thus, even when the rear end10cof the hood panel10is raised, the front end10fof the hood panel10is prevented from being raised apart from the body1by the latch8bwhich locks the lock striker8a.

Further, as shown inFIGS. 2, 3, a cowl7is provided at the rear of the hood panel10, and this cowl7is made up of a highly rigid cowl panel7awhich belongs to the body1and a cowl louvered panel7bof synthetic resin which is situated above the cowl panel7a. The cowl louvered panel7bis provided so as to continuously connect to a lower portion3aof a front windshield3at a rear end portion thereof. As shown inFIG. 1, front pillars4,4are provided at the left and right of the front windshield3.

As shown inFIGS. 4, 8, the actuator21of the first embodiment includes a gas generator70which generates an operation gas G when the actuator21is actuated, an accommodation-side portion22which accommodates the gas generator70to hold it and a push-side portion (also, referred to as a moving-side portion)52which is pushed by the operation gas G which is generated from the gas generator70to move forwards relatively so as to move away from the accommodation-side portion22to thereby push the actuator21to extend. In the first embodiment, when the actuator21is actuated, the gas generator70generates the operation gas G, whereupon the push-side portion52advances obliquely upwards and rearwards relative to the accommodation-side portion22to extend (refer toFIGS. 2, 3) to thereby cause the connecting portions14c,15awith the hinge arm14and the mounting plate15to move away from each other. Then, as this occurs, an intersecting angle θ0between the hinge arm14and the mounting plate15is increased, and the hood panel10is raised at the rear end10cwhile the front end10fwhich is locked by the latch8bis prevented from being raised.

The gas generator70uses a squib or a micro gas generator which ignites predetermined gunpowder, not shown, to thereby generate operation gas G by means of combustion of the gunpowder itself or combustion of a gas generating agent which is ignited by the gunpowder when actuated. Lead wires70c, which are input members through which an ignition signal (an operation signal) is inputted from the control circuit, not shown, are connected to a proximal portion side of the generator70which lies away from a distal end70afrom which the operation gas G is discharged. When an ignition signal is inputted thereinto from the control circuit, not shown, the gas generator70ignites the gunpowder incorporated therein for combustion and further also causes the gas generating agent to burn as required so as to generate combustion gas. Then, the combustion gas is discharged from the distal end70aas the operation gas G to be supplied to a ceiling wall portion53of the push-side portion52. Additionally, in the case of the first embodiment, the gas generator70is configured as an assembly75which is formed integrally with a resin portion72of synthetic resin such as polyamide in such a way as to be accommodated within an inner case27of the accommodation-side portion22with the lead wires70cleft projecting and is accommodated in the inner case27as the assembly75. Further, in the first embodiment, an opening27cat a proximal end side of the lead wires70cwhich project from the inner case27is filled with a seal material82which is made from the same material as that of the seal member81so as to close the circumferences of the lead wires70c, thereby the waterproofness being ensured.

The assembly75is inserted from the opening27cat a proximal end24aof the inner case27(the accommodation-side portion22) so that a collar portion70bof the gas generator70is brought into abutment with a step38, which will be described later, of the inner case27. The assembly75is prevented from being dislocated from the inner case27by a substantially annular retainer44and is accommodated to be held in the accommodation-side portion22(the inner case27). As shown inFIGS. 4, 6, the retainer44is fitted in an assembling hole40opened in the inner case27to be fixed in place therein. The seal material82is filled in the opening27cthrough molding after the retainer44is fitted in the assembling hole40and is then left set up to stay therein.

The accommodation-side portion22of the actuator21is formed of the substantially cylindrical metallic inner case (the cylindrical member)27which is made of steel. The accommodation-side portion22includes an open end23which is opened circularly at a distal end side (an upper end side shown inFIGS. 4, 8) for discharging the operation gas G and the gas generator70which is provided at a proximal portion24side which lies away from the open end23, and the proximal end24aside is connected to the hinge arm14. The connecting portion25which is connected to the hinge arm14includes a connecting hole portion25a. Thus, the actuator21is connected rotatably to the connecting portion14cof the hinge arm14by making use of a pivot device (a pivot pin)18which is inserted through the connecting hole portion25a. The pivot device18penetrates the connecting hole portion25ato be connected rotatably to the connecting portion14cof the hinge arm14. In the case of the first embodiment, the connecting hole portion25amakes use of an inner circumferential through hole of the retainer44which is fixed in the assembling hole40of the inner case27for accommodating to hold (for restricting the dislocation of) the assembly75.

The inner case27which makes up the accommodation-side portion22includes a flange portion28which projects at a distal end (the open end23) side of an outer circumferential surface27aand the step38which is provided on an inner circumferential surface27bon the proximal portion24side so as to narrow its bore diameter towards the open end23side. As has been described before, the collar portion70bof the gas generator70which is covered by the resin portion72is brought into abutment with the step38.

As shown inFIGS. 4, 9, an annular grove29and an accommodation groove30are provided on an outer circumferential surface of the flange portion28sequentially in that order from a distal end side. An annular seal material (a packing, an O ring)46of rubber is fitted in the annular groove29so as to ensure the gas sealing properties of the push-side portion52when it advances.

A lock ring50is accommodated in the accommodation groove30. The lock ring50makes up a reverse preventing lock mechanism BR for preventing the reverse of the push-side portion52when actuation of the actuator21is completed. The lock ring50is made up of a C ring of spring steel having a circular cross section and adapted to be elastically deformed. The accommodation groove30includes a bottom surface32, a step surface33on a side of the bottom surface32which faces the annular groove29and an inclined tapered restricting surface31on a side of the bottom surface32which lies away from the step surface33.

A step surface of the flange portion28which projects from the outer circumferential surface27aacts as a restricting surface28afor restricting the dislocation of the push-side portion52which stops a distal end portion54aside of the push-side portion52when the actuator21is actuated to operate, restricting a maximum extension (a maximum operation stroke) of the actuator21. Because of this, the flange portion28functions as a stopper when the push-side portion52advances.

Additionally, as has been described before, the assembling hole40which is at right angles to an axis C of the actuator21is formed in the inner case27on the proximal end24aside thereof so that the retainer44can be fitted to be fixed therein.

The push-side portion (the moving side portion)52of the actuator21is made of metal such as steel and includes the ceiling wall portion53which covers the open end23side of the accommodation-side portion22and a substantially cylindrical circumferential wall portion54which extends towards the reverse side of the push-side portion52, that is, downwards inFIGS. 4, 8so as to cover an outer circumference of the accommodation-side portion22from an outer circumferential edge of the ceiling wall portion53to at least the proximal portion24side where the gas generator70is disposed.

A connecting portion62is provided on an upper surface side of the ceiling wall portion53which lies away from the open end23, and this connecting portion62has a round hole-like connecting hole portion62avia which the connecting portion62is connected to the mounting plate15. This connecting portion62is connected rotatably to the connecting portion15aof the mounting plate15by making use of a pivot device (a pivot pin)19which is inserted through the connecting hole portion62a. The pivot device19penetrates the connecting hole portion62ato be connected rotatably to the connecting portion15aof the mounting plate15.

The circumferential wall portion54is configured into a smooth circular arc-like surface which is concentric with an axis C of the actuator21(that is, a traveling center axis C of the push-side portion52) so as to advance while ensuring the gas sealing properties with an inner circumferential surface54bextending to a locking step portion65which is provided on the inner circumferential surface at a distal end portion54awhich lies away from the ceiling wall portion53made slidable on the seal material46retained on the outer circumferential surface of the accommodation-side portion22.

The locking step portion65makes up the reverse preventing lock mechanism BR together with the lock ring50and the tapered restricting surface31of the accommodation groove30. The locking step portion65includes an outer circumferential restricting surface67which is an arc-shaped surface parallel to the axis C, constituting a bottom surface of the locking step portion65and a locking restricting surface66which reduces its bore diameter from an edge at an advancing side of the outer circumferential restricting surface67towards the advancing side to thereby be formed into a tapered surface which continuously connects to the inner circumferential surface54b(refer toFIG. 9).

The reverse preventing lock mechanism BR will be described. In the first embodiment, before the actuator21is actuated, the lock ring50is accommodated in the accommodation groove30while being narrowed diametrically as a result of the contact with the inner circumferential surface54bof the push-side portion52or while being allowed to expand (refer toFIG. 4). Then, when the push-side portion52advances completely, the lock ring50expands diametrically and is accommodated in the locking step portion65of the push-side portion52, as shown inFIGS. 8, 9. The lock ring50is set so that a cross-sectional diametric dimension is larger than a width dimension of the locking restricting surface66of the locking step portion65(a width dimension between the outer circumferential restricting surface67and the inner circumferential surface54b) and a dimension half the diametric dimension (a radial dimension) is substantially equal to or slightly smaller than the width dimension of the locking restricting surface66. Because of this, when the lock ring50is accommodated in the locking step portion65, the lock ring50strikes the outer circumferential restricting surface67of the locking step portion65, and the lock ring50(an inner circumferential portion50a) projects from the inner circumferential surface54bof the push-side portion52. Additionally, when the push-side portion52attempts to reverse after its advancement has completed with the lock ring50accommodated in the locking step portion65, even though the locking restricting surface66of the push-side portion52strikes the lock ring50, the lock ring50strikes the tapered restricting surface31, staying stationary, and the lock ring50is locked between the locking restricting surface66and the tapered restricting surface31(refer toFIG. 9).

As a result, even though the push-side portion52attempts to reverse after its advancement has completed, when the push-side portion52is in a lock position RP, the tapered restricting surface31of the accommodation-side portion22strikes the inner circumferential portion50aof the lock ring50which is accommodated in the locking step portion65and an outer circumferential portion50bof the lock ring50is prevented from expansion by the outer circumferential restricting surface67. In this state, since the lock ring50is locked so as not to be dislocated from the locking restricting surface66, the reverse of the push-side portion52is prevented. Consequently, in the case of the first embodiment, the reverse preventing lock mechanism BR for preventing the reverse of the push-side portion52after its advancement has completed is made up of the locking step portion65on the push-side portion52which includes the locking restricting surface66and the outer circumferential restricting surface67, the lock ring (the reverse restricting member)50which is accommodated in the accommodation groove30on the accommodation-side portion22while being biased to expand diametrically, and the tapered restricting surface31of the accommodation groove30of the accommodation-side portion22.

Additionally, a ring holder60is provided at an end edge54aeside of the distal end portion54aof the circumferential wall portion54. The ring holder60is a substantially cylindrical member made of metal such as steel and is clamped to be fixed to an inner circumferential side of the distal end portion54aof the circumferential wall portion54. An inner circumferential surface61of the ring holder60is formed into a smooth circular arc-shaped surface which is concentric with the axis C. The ring holder60is set so as to be brought into abutment with the flange portion28, which acts as a stopper of the accommodation-side portion22, when the push-side portion52has advanced completely. The inner circumferential surface61can slide on the outer circumferential surface27aof the accommodation-side portion22and guides the advancement of the push-side portion52along the axis C.

Further, a plurality of exhaust ports55, which penetrate the circumferential wall portion54from the outer circumference to the inner circumference, are formed near a central portion between the ceiling wall portion53and the end edge54aeof the circumferential wall portion54. A cover56, which is made up of a heat-shrinkable film, is placed on an outer circumferential side of the circumferential wall portion54so as to cover the exhaust ports55. The exhaust ports55are provided to discharge extra operation gas G therethrough and are opened in a position where the open end23of the accommodation-side portion22is surpassed to discharge the operation gas G therethrough when the actuator21is actuated to operate. When the operation gas G is discharged, the cover56is dislocated from the exhaust ports55or is fractured by means of the heat and pressure of the operation gas G.

A seal material81is filled in a gap (a seal portion)78which is opened between an inner circumferential side of the end edge54aeof the push-side portion52and an outer circumferential side of the proximal portion24of the accommodation-side portion22, in other words, the seal portion78on an external surface side between the push-side portion52and the accommodation-side portion22before the actuator21is actuated to operate. The seal material81is so provided by being filled and set through molding. The joining force between the push-side portion52and the accommodation-side portion22at the seal material81can resist sufficiently a moment applied when the hood panel10is opened and closed in the normal use by which the connecting portions14c,15aof the hinge arm14and the mounting plate15are caused to move away from each other and is set so that the end edge54aeof the push-side portion52can be dislocated from the outer circumferential surface27anear the opening27cof the accommodation-side portion22, that is, so that the push-side portion52can advance when the gas generator70is actuated to operate.

In the case of the first embodiment, a hot melt adhesive formed from a polyester resin of a melting temperature of 200 to 260° C. and a injection pressure of 10 to 20 Mpa (an adhesive marketed under a product name of “VYLOSHOT: GM-960” by TOYOBO CO., LTD.) is used as the seal material81.

As indicated by chain double-dashed lines inFIG. 5, the seal member81is formed by the use of an injection molding mold85which is made up of a pair of split mold halves86,87. The split mold halves86,87include mold surfaces86a,87awhich define a cavity85for the seal portion78and which support the end edge54aeand the inner case27. A gate85bis formed in the split mold half86for pouring a molten filler (a hot melt adhesive)80for forming the seal material81into the cavity85a.

In the case of the first embodiment, as indicted by chain double-dashed lines inFIG. 7, the mold85includes a cavity85cinto which the filler80can be poured also at a seal portion79which surrounds the circumferences of the lead wires70cin the opening27cof the accommodation-side portion22. Because of this, in the split mold halves86,87, corresponding mold surfaces86b,87band a gate85dare formed.

In molding, the actuator21to which all the constituent parts excluding the seal materials81,82are assembled is set in the open mold85. Then, after the mold85is closed, the filler80is poured to fill the cavities85a,85cthrough the gates85b,85dand is then cooled to be set. Then, the mold is released to open, whereby the actuator21with the seal materials81,82can be fabricated.

It is noted that other hot melt adhesives or rubber materials may be used as long as they can be used as a seal material which doubles as an adhesive while ensuring a predetermined connecting or joining force. However, it is desired that those replacement materials can be formed at a melting temperature at which the gunpowder in the gas generator70is not ignited and at a pouring or injecting pressure at which no damage is made to the gas generator70. Therefore, it is desirable to use a filler which can be formed at a melting temperature of 250° C. or lower and a pouring or injecting pressure of the order of 25 Mpa or lower.

The seal materials81,82can ensure the waterproofness and can prevent the intrusion of dust into the actuator21.

In the actuator21which is fabricated as described heretofore, the lead wires70c,70care connected to the control circuit, not shown, and connecting portions25,62are connected to the connecting portions (the connecting locations)14c,15aof the hinge arm14and the mounting plate15of each of the left and right hinge mechanisms11on the hood panel10by making use of the pivot devices18,19, whereby the actuators21can be provided in the hinge mechanism11, and the pop-up apparatuses U can be mounted on the vehicle V.

In the pop-up apparatus U of the first embodiment which is mounted on the vehicle V, in the event that the actuator21is actuated to operate, the operation gas G is generated by the gas generator70, the seal material81is separated from the accommodation-side portion22as indicated by the chain double-dashed lines and the solid lines inFIG. 3or as shown inFIGS. 4 to 8, by means of a pressure of the operation gas G, and the push-side portion52of the actuator21moves away from the accommodation-side portion22, whereby the actuator21is allowed to extend. Then, the actuator21which is extending widens the intersection angle θ0between the mounting plate15and the hinge plate14, which raises the hood panel10at the rear end10cthereof, whereby the hood panel10can ensure a wide deformation space S so that the hood panel10can be deformed largely and can receive a pedestrian while mitigating an impact.

In the case of the first embodiment, the operation stroke of the actuator21is about 40 mm, and the rear end10cof the hood panel10can be raised about 80 mm.

Additionally, when the push-side portion52advances so that the exhaust ports55pass the flange portion28of the accommodation-side portion22, the operation gas G moves the cover56closing the exhaust ports55or pushes the cover56to open (or to melt) partially the cover56, whereby extra operation gag G is discharged from the exhaust ports55.

In the actuator21of the first embodiment, before the actuator21is actuated to operate, the seal material81which doubles as the adhesive closes the gap (the seal potion)78between the push-side portion52and the accommodation-side portion22, and therefore, the intrusion of rain water into the gas generator70can be prevented, whereby the waterproofness of the actuator21is ensured. Additionally, before the actuator21is actuated to operate, the seal material81which doubles as the adhesive join the push-side portion52and the accommodation-side portion22together at the seal portion78, whereby the relative advancement of the push-side portion52to the accommodation-side portion22can be restricted, and the extension of the actuator21can be prevented before the actuator21is actuated to operate. In addition, the seal material81which doubles as the adhesive joins the push-side portion52and the accommodation-side portion22together with the joining force which enables the push-side portion52to advance relatively when the actuator21is actuated to operate. Therefore, when the actuator21is actuated to operate with the operation gas G generated from the gas generator70, the push-side portion52releases the adhesion to the accommodation-side portion22and can move smoothly relative to the accommodation-side portion22.

In the actuator21of the first embodiment, the seal material81which doubles as the adhesive is filled to be set through molding, and the seal material (the filler)80can easily be filled in the seal portion78which is disposed on the external surface side of the actuator21for provision therein. Further, in the actuator21of the first embodiment, although a filling machine (an injection machine) to fill the filler80in the mold85and the cavities85a,85cis necessary, the conventionally required labor-hours to design to provide the packing, the packing accommodation groove, the E ring and the E ring accommodation groove or to assemble them together are unnecessary, and therefore, the actuator21can be formed in a simple and easy fashion.

Consequently, in the actuator21of the first embodiment, although the gas generator70is used which generates the operation gas G when it is actuated, both the waterproofness and the prevention of the extension of the gas generator70before actuation can be ensured.

In the actuator21of the first embodiment, the accommodation-side portion22is configured so that the lead wires70c,70c, which are the input members for inputting the operation signal of the gas generator70, are left projecting to the exterior portion from the opening27cof the inner case27. However, a seal material82, which is made up of the filler80as with the seal material81, is filled and set also in the portion where the lead wires70c,70cof the accommodation-side portion22are caused to project so as to be set therein.

Because of this, in the first embodiment, in filling the seal material81in the gap (the seal portion)78between the push-side portion52and the accommodation-side portion22, the seal material82can be filled simultaneously around the circumference (the seal portion)79of the input members of the accommodation-side portion22. As a result, in the configuration like this, the stable waterproofness of the whole of the actuator21including the waterproofness around the lead wires70c,70ccan easily be ensured.

In the first embodiment, while the connecting portion25of the accommodation-side portion22of the actuator21is connected to the hinge arm14and the connecting portion62of the push-side portion52is connected to the mounting plate15, a reverse configuration may be provided in which the connecting portion25of the accommodation-side portion22is connected to the connecting portion15aof the mounting plate15, and the connecting portion62of the push-side portion52is connected to the connecting portion14cof the hinge arm14.

Next, an actuator121of a second embodiment shown inFIGS. 10, 11will be described. As with the actuator21of the first embodiment, the actuator121of the second embodiment is used for a hood pop-up apparatus U in such a way as to connect a hinge arm14and a mounting plate15together of a hinge mechanism11.

However, in the second embodiment, the actuator121is of a cylinder type, and an accommodation-side portion122includes a bottom wall portion127which accommodates and holds a gas generator185, a ceiling wall portion123which is provided so as to face the bottom wall portion127, and a cylindrical circumferential wall portion126which extends from an outer circumferential edge of the bottom wall portion127to the ceiling wall portion123. A piston portion153of a push-side portion (a movable-side portion)152is made to slide on an inner circumferential surface126aof the circumferential wall portion126.

The push-side portion (the movable-side portion)152is configured as a piston rod having the piston portion153which slides on the inner circumferential surface126aof the circumferential wall portion126and a rod portion155which extends from the piston portion153to project from an insertion hole124of the ceiling wall portion123.

The piston rod (the push-side portion)152has an accommodation recess portion which accommodates the gas generator185in an end face of the piston portion153which faces a bottom wall portion127of the cylinder (the accommodation-side portion)122. The piston rod (the push-side portion)152includes an opposite wall portion158which makes up a ceiling surface157aof the accommodation recess portion157and faces oppositely the gas generator185, and a slidable cylindrical portion159which extends from an outer circumferential edge of the opposite wall portion158to the bottom wall portion127of the cylinder122while covering the circumference of the gas generator185and which makes up an inner circumferential surface157bof the accommodation recess portion157while made to slide on the inner circumferential surface126aof the cylinder (the accommodation-side portion)122on an outer circumferential surface thereof.

Similar to the gas generator70of the first embodiment, the gas generator185uses a squib or a micro gas generator which ignites predetermined gunpowder, not shown, to thereby generate operation gas G by means of combustion of the gunpowder itself or combustion of a gas generating agent which is ignited by the gunpowder when actuated. A connector185bis provided at a proximal portion side lies away from a distal end185afrom which the operation gas G is discharged and which projects from the bottom wall portion127, lead wires, not shown, through which an ignition electrical signal (an operation signal) is inputted from a predetermined control circuit are connected to the connector185b. Similar to the gas generator70of the first embodiment, when an ignition signal is inputted into the gas generator185from the control circuit, not shown, in the gas generator185, a gun powder incorporated in the gas generator185is ignited for combustion, and further, a gas generating agent is also caused to burn as required to thereby generate combustion gas, and the combustion gas so generated is discharged from the distal end185ato be supplied to the accommodation recess portion157in the piston portion153as operation gas G.

In this actuator121of the second embodiment, too, when the gas generator185generates the operation gas G, the piston rod152as the push-side portion advances to extend relative to the cylinder122as the accommodation-side portion, causing the connecting portions14c,15awith the hinge arm14and the mounting plate15to move away from each other (refer toFIGS. 2, 3). This increases an intersection angle θ0between the hinge arm14and the mounting plate15, whereby a hood panel10is raised at a rear end10cwithout being raised at a front end10fwhich is locked by a latch8b.

In the cylinder122as the accommodation-side portion, a cap material which makes up the ceiling portion123is crimped to a metallic cylindrical pipe material, and the proximal portion side of the cylinder122is also crimped to form the bottom wall127side. A locking step portion (an annular groove)130for locking a lock ring180which makes up a reverse preventing lock mechanism BR is formed on an inner circumferential side of the circumferential wall portion126near the ceiling wall portion123. The locking step portion130includes an outer circumferential restricting surface132which restricts the diametrical expansion of the lock ring180as a bottom surface of the annular groove and a locking restricting surface131which extends from an edge of the outer circumferential restricting surface132at a reverse side of the piston rod152towards an axis C of the actuator121to lock the lock ring180.

When in actuation, the ceiling wall portion123is brought into abutment with the piston portion153of the piston rod152to thereby constitute a stopper which restricts a maximum operation stroke of the actuator121.

Further, in the cylinder122, a connecting portion129is secured to an outer circumferential surface of the bottom wall portion127for connection to a connecting portion (an accommodation-side connecting portion)14cof the hinge arm14. A connecting hole portion129ais provided in the connecting portion129for insertion of a pivot device18. Then, the connecting portion129is connected rotatably to the connecting portion14cof the hinge arm14by making use of the pivot device18which is connected rotatably to the connecting portion14c.

The piston rod152as the push-side portion includes an accommodation groove162which accommodates the lock ring180and a recessed groove portion160in which a seal material170is fitted in which are provided on an outer circumferential surface of the piston portion153sequentially in that order from an advancing side. The seal material170is made up of an O ring and slides on an inner circumferential surface126aof the circumferential wall portion126of the cylinder122while ensuring the gas seal properties when the piston portion153advances.

The accommodation groove162accommodates the lock ring180and includes a tapered restricting surface163which expands diametrically from an advancing side edge of a bottom surface164and a step surface165which extends towards an axis C from a reverse side edge of the bottom surface164. The tapered restricting surface163is an inclined surface which expands diametrically from the bottom surface164to the advancing side (an upper side inFIGS. 10, 11) and is inclined at an inclination angle of 45° with respect to the axis C.

The lock ring180makes up the reverse preventing lock mechanism BR which restricts the reverse of the piston rod152after the actuator121has completed its operation. The lock ring180is made up of a C ring of spring steel which has a circular cross section and which can elastically be deformed. The lock ring180is accommodated in the accommodation groove162while being narrowed diametrically as a result of the contact with the inner circumferential surface126aof the cylinder122or while being allowed to expand. Then, when the piston rod152has advanced completely, the lock ring180expands diametrically and is accommodated in the locking step portion130of the cylinder122. The lock ring180is set so that a cross-sectional diametric dimension is larger than a width dimension of the locking restricting surface131of the locking step portion130(a width dimension between the outer circumferential restricting surface132and the inner circumferential surface126a) and a dimension half the diametric dimension (a radial dimension) is substantially equal to or slightly smaller than the width dimension of the locking restricting surface131.

Namely, the diametric dimension of the lock ring180is set larger than the width dimension of the locking restricting surface131so that when the lock ring180is accommodated in the locking step portion130, the lock ring180strikes the outer circumferential restricting surface132of the locking step portion130to thereby project from the inner circumferential surface126aof the cylinder122. In addition, the radial dimension of the lock ring is set substantially equal to or slightly smaller than the width dimension of the locking restricting surface131so that when the lock ring180is accommodated in the locking step portion130and the piston rod152attempts to reverse after its advancement has completed, even though the tapered restricting surface163of the piston rod152strikes the lock ring180accommodated in the locking step portion130, the lock ring180strikes the locking restricting surface131to thereby be locked in such a way that the lock ring180is not dislocated from the locking restricting surface131.

Because of this, even though the piston rod152attempts to reverse after its advancement has completed, in the lock position RP of the piston rod152, the tapered restricting surface163of the piston rod152strikes an inner circumferential portion180aof the lock ring180which is accommodated in the locking step portion130, and an outer circumferential portion180bof the lock ring180is locked so as not to be dislocated from the locking restricting surface131. Thus, the reverse of the piston rod152is prevented. Consequently, in the case of the second embodiment, the reverse preventing lock mechanism BR which prevents the reverse of the piston rod152after its advancement has completed is made up of the locking step portion130including the locking restricting surface131and the outer circumferential restricting surface132on the cylinder122, the lock ring (the reverse restricting member)180which is accommodated in the accommodation groove162while being biased in the direction in which the piston rod152expands diametrically, and the tapered restricting surface163of the accommodation groove162of the piston rod152.

A connecting portion156ais provided at an end side of the rod portion155of the piston rod152which constitutes a distal end side when the piston rod152advances. This connecting portion156has a connecting hole portion156a, which is a circular hole, and is connected to the mounting plate15. This connecting portion156is connected rotatably to the connecting portion15aof the mounting plate15by making use of a pivot device (a pivot pin)19which is inserted through the connecting hole portion156a(refer toFIG. 2). The pivot device19passes through the connecting hole portion156aand is connected rotatably to the connecting portion15aof the mounting plate15.

In addition, a seal material191which doubles as an adhesive is filled to be set in a gap (a seal portion on an outer circumferential surface of the actuator121)189which is defined between an end edge outer circumferential surface156bat a lower end of the connecting portion156and an end edge inner circumferential surface126bon the circumferential wall portion126of the cylinder122at the advancing side. This seal material191joins the piston rod (the push-side portion)152and the cylinder (the accommodation-side portion)122together while ensuring the waterproofness of the interior of the cylinder before the actuation of the actuator121. This seal material191is provided by pouring or injecting a hot melt adhesive (a filler)80similar to the seal materials81,82of the first embodiment and setting it through molding.

Similar to the first embodiment, the joining force between the piston rod152and the cylinder122at the seal material191can resist sufficiently a moment applied when the hood panel10is opened and closed in the normal use by which the connecting portions14c,15aof the hinge arm14and the mounting plate15are caused to move away from each other and is set so that the connecting portion156of the piston rod152can be dislocated from the circumferential wall portion126of the cylinder122, that is, so that the piston rod152can advance when the gas generator185is actuated to operate.

In the second embodiment, too, lead wires from a control circuit, not shown, are connected to the connector185bof the gas generator185in the actuator121, and the connecting portions129,156are connected to the connecting portions (the connecting locations)14c,15aof the hinge arm14and the mounting plate15in the left and right hinge mechanisms11of the hood panel10by making use of the pivot devices18,19, whereby the actuator121can be provided in the hinge mechanism11, and the pop-up apparatus U can be mounted on the vehicle V (refer toFIGS. 1, 2).

In the pop-up apparatus U of the second embodiment which is mounted on the vehicle V, in the event that the actuator121is actuated to operate, the operation gas G is generated by the gas generator185, the seal material191is separated from the end edge inner circumferential surface126bof the cylinder122as shown inFIGS. 10, 11by means of a pressure of the operation gas G, and the rod portion155of the piston rod152as the push-side portion152of the actuator121is caused to project from the cylinder122, whereby the actuator121is allowed to extend. Then, similar to the first embodiment, the actuator121which is extending widens the intersection angle θ0between the mounting plate15and the hinge plate14, which raises the hood panel10at a rear end10cthereof (refer toFIGS. 2, 3), whereby the hood panel10can ensure a wide deformation space S so that the hood panel10can be deformed largely and can receive a pedestrian while mitigating an impact.

In the actuator121of the second embodiment, too, the same working effect as that of the first embodiment can be obtained.

In the second embodiment, the gas generator185includes the connector185bhaving the seal properties, and although no seal member which is set after being poured is not provided on the circumference of the connector185b, in case it is necessary, such a seal material may be provided separately.

In addition, in the second embodiment, too, while the connecting portion129of the cylinder122as the accommodation-side portion of the actuator121is described as being connected to the hinge arm14, and the connecting portion156of the piston rod152as the push-side portion is described as being connected to the mounting plate15, an opposite configuration may be adopted in which the connecting portion129of the cylinder122is connected to the connecting portion15aof the mounting plate15and the connecting portion156of the piston rod152is connected to the connecting portion14cof the hinge arm14.

Further, in the first and second embodiments, the accommodation-side portion22,122and the push-side portion52,152are described as being connected to the accommodation-side connecting portion14cand the push-side connecting portion15aby being provided the predetermined connecting portions25,129before actuation. However, a configuration may be adopted in which at least either of the accommodation-side portion22,122and the push-side portion52,152is fixedly connected to a fixed side connecting portion (a fixed-side connecting location), while the other of the accommodation-side portion22,122and the push-side portion52,152is provided to be spaced apart from a movable-side connecting portion (a connecting location) which is spaced apart from the fixed-side connecting portion before actuation, and when actuated, the other of the accommodation-side portion22,122and the push-side portion52,152is brought into contact with (joined, connected to) the movable-side connecting portion so as to support or move the movable-side connecting portion. In this configuration, since the lead wires70cneed to be provided to input the ignition signal (the operation signal) to the gas generator70,185, when considering the routing of the lead wires70cor the space needed to deal with the movement of the lead wires70c, it is desirable to adopt a configuration in which the accommodation-side connecting portion of the accommodation-side portion22,122constitutes the fixed-side connecting portion, while the push-side connecting portion of the push-side portion52,152constitutes the movable-side connecting portion, and the push-side portion52,152is provided to be spaced apart from the movable-side connecting portion in such a way as to be brought into contact with (joined, connected to) the movable-side connecting portion when actuated.

Furthermore, in the first and second embodiments, while the actuator21,121is described as being applied to the pop-up apparatus U for popping up the hood panel10, the actuator may be applied to an actuator for a head protection apparatus in which a headrest is divided into two front and rear portions, so that a front headrest portion is made to advance when the vehicle is involved in a collision or a knee protection apparatus in which an accommodation-side portion and push-side portion are connected to a knee panel in front of the seated driver and a body-side reinforcement, so that the knee panel is moved to the rear when the vehicle is involved in a frontal collision. Further, the actuator of the invention is not limited to those of the embodiments, as long as the gas generator is actuated to operate so that the push-side portion is moved relative to the accommodation-side portion and hence can be applied to various types of automotive safety apparatuses.