JP4287879B2 - Active headrest headrest tilting device - Google Patents

Description

  The present invention relates to a headrest tilting device for an active headrest provided with a head protection function.

  A headrest with a head protection function that protects the head of an occupant (hereinafter referred to as an active headrest) is known in which a headrest attached to the upper part of a seat moves forward when a vehicle is rear-end collision.

  As the tilting device for the active headrest, for example, a wire driving unit is provided at the lower part of the seat back, a headrest driving unit is provided at the upper part of the seat back, and the There is known a wire drive type in which the drive unit uses the pressure as the tension of the wire and tilts the headrest forward with the tension transmitted to the headrest drive unit.

Further, there is known a structure in which a pressure receiving plate is provided on the seat back and the headrest moves forward when the pressure receiving plate is rotated by the pressure of the occupant during the rear-end collision.
JP 2001-58533 A

  However, when the headrest drive unit and the wire drive unit are connected with a wire as in the past, or when the pressure receiving plate and the headrest are connected with a connecting member, if the head of the occupant hits the headrest strongly, the force of the headrest is driven by the wire The headrest may be pushed back toward the rear of the vehicle by returning to the portion (pressure receiving plate) side. Then, the head moves rearward as it is, and the protecting function is not sufficiently exhibited.

  For the above problem, it was considered to provide a ratchet mechanism or a lock mechanism in the drive unit, but when the ratchet mechanism is provided, the mechanism becomes complicated, and when the headrest is pushed backward, There was a problem that the headrest returned backward to the position where the engagement teeth of the ratchet mechanism were engaged. Further, when the lock mechanism is provided, if the head hits the headrest before the lock is activated, the headrest is not locked and returns to the rear as it is, and the effect of protecting the head cannot be obtained.

  Further, since the headrest is movably attached to the active headrest, the headrest can be easily moved or rattled when the headrest is pushed forward during normal times.

  The present invention provides a headrest tilting device for an active headrest that can stably fix a headrest at a predetermined position on a seat back in a normal state and that operates in an emergency in order to protect an occupant's head. For the purpose.

  In the present invention, the headrest tilting device for the active headrest is configured as follows. In other words, it comprises a wire drive unit provided at the lower part of the seat back, a headrest drive unit provided at the upper part of the seat back, and a tension transmission member for connecting the wire drive unit and the headrest drive unit. In the headrest tilting device of the active headrest that converts the pressure when moving rearward relative to the drive portion) into the tensile force of the tension transmission member and operates the headrest forward by the tensile force, at least the headrest drive portion A protrusion protruding inward of the holding portion is provided on the upper rear surface of the holding portion, and a cam crest corresponding to the protrusion is formed on the support bracket that is held by the holding portion so as to be movable in the vertical direction.

  When a rearward force is applied to the headrest by the head of the occupant, the cam mount is fixed to the protrusion and the support bracket is fixed at any position.

  A first engaging portion is provided at the upper end of the holding portion, a second engaging portion is provided at the upper portion of the support bracket, and when the support bracket is stored, a second engaging portion is provided on the front inclined surface of the first engaging portion. The joint was brought into contact and fixed.

  Hereinafter, a headrest tilting device for an active headrest according to the present invention will be specifically described. The headrest tilting device includes a wire drive unit, a tension transmission member (wire) that transmits a driving force, and a headrest drive unit.

  The wire drive unit includes a link mechanism or the like, and is attached below the seat back frame, for example, facing the occupant's waist seated on the vehicle seat. One end of a tension transmission member is connected to the wire drive unit, and when the occupant moves rearward relative to the seat back, the wire drive unit generates tension in the tension transmission member.

  The tension transmitting member includes a flexible outer cylinder and a linear member provided in the outer cylinder. When one end of the linear member is pulled with respect to the outer cylinder, the tension is transmitted to the other end. The In the present specification, such a tension transmission member is also referred to as a wire.

  The headrest driving unit includes a frame plate as a mounting substrate, a holding unit, a support bracket, an operating unit, and the like, and is fixed to the upper portion of the seat back frame by screws with the frame plate.

  The holding portion is cylindrical and is provided in parallel on both the left and right sides of the frame plate. Support brackets are housed in the left and right holding portions so as to be movable along the longitudinal direction (the vertical direction of the vehicle). A protrusion is formed on the inner surface of the holding portion.

  The protrusion is provided at least on the rear surface of the holding portion (the front-rear direction of the vehicle is the front-rear direction). Preferably, the protrusion formed on the rear surface of the holding portion is disposed at one location on each of the front and rear surfaces so as to be disposed above the protrusion formed on the front surface. The top of the protrusion is preferably long in the lateral direction, and the top is in line contact with the support bracket.

  A first engaging portion is formed on the upper edge of the holding portion. The first engagement portion corresponds to a second engagement portion formed on a support bracket described later, and engages with the second engagement portion when the support bracket is stored in the holding portion. The first engaging portion is formed with an inclined surface with at least the front facing upward, whereby the second engaging portion is moved rearward along the inclined surface when contacting the first engaging portion. It is energized towards.

  More preferably, the first engaging portion is formed by notches formed at three locations, a surface facing the rear of the vehicle and a surface facing left and right. A parallel long portion along the longitudinal direction of the holding portion is formed on the rearward facing surface, and a longitudinal portion formed in parallel with the longitudinal direction of the holding portion is formed on at least one of the left and right surfaces. It forms in the shape which consists of a part and the inclination part which spreads from a longitudinal part. The tips of the longitudinal portions are all formed in an arc shape. Even in such a shape, when the support bracket is housed in the holding portion, the second engagement portion comes into contact with the inclined surface inclined forward of the first engagement portion.

  The support bracket has a cylindrical shape, and has a cam crest corresponding to the protrusion on the outer surface. A headrest support is attached inside the support bracket. The headrest support is always exposed on the upper surface of the seat back, and the headrest stay is inserted into the headrest support to hold the headrest at an appropriate height above the seat back.

  The cam crest constitutes a cam mechanism in combination with the protrusion. The cam crest may be formed on both the front and rear surfaces of the support bracket, or one of them may be formed flat. The support bracket is tilted forward of the vehicle by the cam mechanism.

  The cam crest and the protrusion stick to each other when the head of the occupant hits and the headrest is pushed backward at the time of the rear-end collision. As a means for fixing, for example, the support bracket is formed of a material that generates an appropriate frictional resistance against the protrusion. The friction coefficient is appropriately selected from the shape of the cam crest, the arrangement, the shape of the protrusion, and the like.

  Further, the support bracket may be formed of a deformable material such that the cam mountain bites into the protrusion when a backward force is applied to the headrest. The deformation may be elastic deformation or permanent deformation. In addition, you may set suitably the friction coefficient and softness of a protrusion instead of a support bracket with respect to a support bracket.

  A second engagement portion corresponding to the first engagement portion is formed on the upper portion of the support bracket. The second engaging portion is formed in a shape corresponding to the first engaging portion, and when the support bracket is housed in the holding portion, it engages with at least a forward inclined portion of the first engaging portion. To do.

  Specifically, the second engaging portion is formed with a parallel longitudinal portion along the longitudinal direction of the support bracket so as to be fitted to the first engaging portion on the rearward facing surface, and in the left-right direction. A stepped portion having a longitudinal portion formed in parallel along the longitudinal direction of the support bracket and an inclined portion extending from the longitudinal portion is formed on the facing surface in correspondence with the first engaging portion. The tip of the longitudinal portion is formed in an arc shape. When the support bracket is housed in the holding portion, the inclined portion engages with the inclined surface on the front side of the first engaging portion.

  Furthermore, you may comprise a support bracket from the metal inner cylinder and the resin exterior material which has a cam peak.

  For example, the inner cylinder is a cylindrical body having a square cross section to which the headrest support is attached on the inner side, and a pair is assembled to the left and right ends of the connecting plate. The inner cylinders are parallel to each other, and are attached at intervals that match the stay interval of the headrest. A mounting hole for locking the headrest support is formed on the side surface of the inner cylinder. When the inside of the mounting hole is pressed from the outside, the engagement claw is disengaged and the headrest support can be extracted from the support bracket.

  The exterior material has a cylindrical shape that is fitted to the outer periphery of the inner cylindrical body, and is integrally fixed to the inner cylindrical body by an engaging claw. The exterior material is made of a material that generates an appropriate frictional resistance between the protrusions, and is, for example, a polyacetal resin. The coefficient of friction is equal to or greater than the value at which the cam crest sticks to the protrusion when a backward force is applied to the headrest. The cam crest may be formed on both the front and rear surfaces of the exterior material, or one of them may be formed flat.

  Moreover, you may form an exterior material with the raw material which deform | transforms when it contact | abuts to a protrusion. The deformation may be elastic deformation or permanent deformation, and it is sufficient that the cam crest is fixed to the protrusion when a backward force is applied to the headrest. As long as it has the above properties, the exterior material is not limited to the resin material, but may be a metal such as aluminum or the like.

  The operating part is a mechanism that raises the pair of support brackets synchronously in response to tension from the wire. For example, a pair of sector gears engaged with each other is provided, one end of a wire is connected to one sector gear, and a connection pin provided on each sector gear is engaged with a connection plate. And when one sector gear rotates by a wire drive part, both sector gears rotate synchronously, a connection board will move up and down in parallel, and the support bracket attached to the connection board will move up and down synchronously. The actuating portion includes a spring member and is always biased in a direction in which the support bracket is housed in the holding portion. In addition, an action | operation part is not restricted to the said structure.

  In the headrest tilting device, the support bracket is reliably tilted forward by the protrusion provided on the holding portion and the cam mountain of the support bracket. When the support bracket is pressed rearward at the time of the rear-end collision, the cam crest is fixed to the protrusion, so that the support bracket is fixed at the position where the pressure is received. Further, when the pressing of the support bracket is released, the sticking between the cam crest and the protrusion disappears immediately, and the support bracket is returned to the holding portion. By abutting at the inclined portion, the support bracket is stored in the holding portion without rattling.

  As a result, the headrest tilts forward during rear-end collision and is fixed without being pushed back, so that the head can be reliably protected. Further, after the operation, the headrest immediately returns to the original position, so that there is no problem in subsequent use. In a normal state, the second engaging portion comes into contact with the inclined surface of the first engaging portion, and the two protrusions of the holding portion and the support bracket come into contact with each other, and the headrest is held without rattling on the seat back. Is done.

An embodiment of a headrest tilting device according to the present invention will be described with reference to the drawings.
FIG. 12 shows a vehicle seat 100 including the headrest tilting device 2. The vehicle seat 100 includes a seat surface 102, a seat back 104, a headrest 3 attached to the upper portion of the seat back 104, and the like. The seat back 104 includes a seat back frame 106, a cushion material (not shown) is provided around the seat back frame 106, and an outer skin 101 is attached to the outer surface of the cushion material as indicated by a two-dot chain line.

  The seat back frame 106 has a shape that substantially conforms to the outer shape of the seat back 104, and includes a side frame 108, an upper frame 110, and a lower frame 112 provided on both the left and right sides. The upper frame 110 connects the left and right side frames 108 above the side frame 108, and the lower frame 112 connects the side frame 108 below the side frame 108.

  A headrest drive mechanism 4 as a headrest drive unit is attached to the front surface of the upper frame 110, and a wire drive mechanism 6 as a wire drive unit is attached to the front surface of the lower frame 112. Between the headrest drive mechanism 4 and the wire drive mechanism 6, a wire 130 as a tension transmission member is provided. The headrest 3 is attached by inserting a stay into the headrest driving mechanism 4 from above. A spring member 120 is attached to the seat back frame 106 so as to cover the inside of the seat back frame 106.

  As shown in FIG. 9, the wire 130 has a double structure composed of an outer tube 132 and a metal strand 134 attached to the inside of the outer tube 132, and by pulling the metal strand 134 on the outer tube 132, Tension is transmitted to the other end of the metal strand 134.

  The headrest drive mechanism 4 is shown in FIG. The headrest driving mechanism 4 includes a frame plate 30 serving as a substrate, holding portions 22 and 24 provided on the left and right of the frame plate 30, a pair of support brackets 12 held inside the holding portions 22 and 24, and a frame plate It is comprised from the action | operation mechanism 50 etc. which were provided in the front surface of 30 as an action | operation part.

  The frame plate 30 is a metal plate, has a screw hole 62 in the upper part, and is fixed to the upper frame 110 using the screw hole 62 as shown in FIG. The holding portions 22 and 24 are rectangular cylinders, and are formed by fixing a substantially U-shaped member to the frame plate 30 by caulking. If sufficient strength is secured, the entire frame plate 30 may be formed of resin.

  Since the holding part 22 and the holding part 24 are attached in parallel and have a bilaterally symmetric relationship, the holding part 22 will be described and replaced with the description of the holding part 24.

  FIG. 6 shows a cross section of the holding portion 22. FIG. 6 shows a state where the support bracket 12 is housed in the holding portion 22. As shown in the drawing, the holding portion 22 has an upper projection 23 and a lower projection 25 formed on the inner surface. The upper projection 23 is formed behind the holding unit 22 (with respect to the vehicle), and the lower projection 25 is formed forward (the same).

  The holding part 22 has a first engaging part 27 at the upper end. The first engaging portion 27 is configured by providing a notch in the left wall 33, the right wall 35, and the rear wall 37 of the holding portion 22. As shown in FIG. 4, the rear wall 37 is formed with a notch 32 as a longitudinal portion extending in parallel with the longitudinal direction (longitudinal direction of the holding portion 22). Further, on the right wall 35 (inward side of the vehicle), as shown in FIG. 5, a notch 34 as a longitudinal portion extending parallel to the longitudinal direction (longitudinal direction of the holding portion 22) and a notch 34 are continuous. Thus, it is formed from an expanded portion 36 as an inclined portion that expands upward. Further, as shown in FIG. 6, the holding portion 22 has a front upper edge 38 that is rounded downward and forward from the upper edge (near the first engaging portion 27) of the rear and left and right walls 37 and 33. It is formed.

  The support bracket 12 has the same shape on the left and right sides, and is fixed to both the left and right sides of the connecting plate 20 (see FIG. 1). The support bracket 12 includes an inner cylindrical body 13 and an exterior body 15 attached to the outer side of the inner cylindrical body 13 as shown in FIG. 2, and is housed inside the holding portion 22 as shown in FIG. .

  The inner cylinder 13 is a metal cylinder, and is formed by, for example, pressing. A headrest support 14 is incorporated into the inner cylinder 13 from above. The upper portion of the headrest support 14 is always exposed on the upper surface of the seat back 104, the stay of the headrest 3 is inserted therein, and the headrest 3 is held at an appropriate height above the seat back 104. The headrest support 14 is fixed by engaging an engagement piece (not shown) in a mounting hole 16 formed on the side wall of the support bracket 12 and pressing the engagement piece to release the engagement results in the support bracket 12. Can be removed from.

  The exterior body 15 is made of polyacetal resin, is fitted on the outer peripheral surface of the inner cylinder body 13, and is integrally fixed to the inner cylinder body 13 with an engagement piece (not shown). The exterior body 15 is formed with a guide portion 9 (see FIG. 2) on the front surface (with respect to the vehicle body) and a rear cam 11 (see FIG. 3) on the rear surface. As shown in FIG. 2, the guide portion 9 is provided above the center in the longitudinal direction of the support bracket 12, and the lower side from the guide portion 9 is formed flat. As shown in FIG. 3, the rear cam 11 is formed gently from a portion slightly above the center in the longitudinal direction of the support bracket 12 to the lower end. The cam mechanism is configured by a combination of the rear cam 11 and the upper protrusion 23 and the front surface of the exterior body 15 and the lower protrusion 25. Such a cam mechanism tilts the support bracket 12 forward when the support bracket 12 moves upward with respect to the holding portion 22 and the like.

  Furthermore, the cam mechanism has a structure that holds the support bracket 12 even when a rearward force is applied to the headrest 3 in a state where the support bracket 12 is pulled out from the holding portion 22. That is, the cam mechanism has a structure in which the headrest 3 does not return downward by the force F (shown in FIG. 7) applied to the headrest 3 regardless of the position of the support bracket 12 with respect to the holding portion 22. Yes.

  For example, suppose that the load applied to the headrest from the head is F, and the load F is received by the two contact points a and b of the cam crest and the protrusion. Then, a vertical drag Na is generated at the point a, a vertical drag Nb is generated at the point b, and if the cam crest and the projection are in contact at an angle Θ at the point a, the force for returning the headrest downward is Nasin Θ. It becomes.

  On the other hand, the frictional forces at the contacts a and b are μNa and μNb, respectively. μ is a coefficient of friction. Therefore, as shown in (Equation 1), if the frictional force (μNa + μNb) is larger than the force NasinΘ for returning the headrest downward, the headrest will not return downward due to the frictional force. Further, Equation 1 is transformed to obtain Equation 2.

μ (Na + Nb)> NasinΘ (Formula 1)
μNa + μNb−NasinΘ = Na (μ−sinΘ) + μNb> 0 (Expression 2)
This will be specifically described. The upper protrusion 23 is a point, and the lower protrusion 25 is a point b. The coefficient of friction between the outer package 15 and the upper and lower protrusions 23 and 25 is μ, and the inclination angle of the rear cam 11 is Θ.

  When a load F is applied to the headrest 3, reaction forces Na and Nb are generated at the upper protrusion 23 (point a) and the lower protrusion 25 (point b), respectively, and as a result, a frictional force, μNa + μNb is generated. Further, the support bracket 12 generates a force, Nasin Θ, for returning the headrest 3 downward.

  Here, when the exterior body 15 is POM (resin) and the upper protrusion 23 and the lower protrusion 25 are iron, μ is about 0.2 and Θ is 8.4 degrees (in the design of the rear cam 11). Then, Na (0.2−sin8.4) + 0.2Nb is obtained from Equation 2, 0.054Na + 0.2Nb> 0, Equation 2 is established, and the stepless lock state is established. To establish. Accordingly, the support bracket 12 is locked at the position where the force is received without being returned downward by the force F applied to the headrest 3 at any position with respect to the holding portion 22.

  In addition, the exterior body 15 has a second engagement portion 29 formed at the top. The second engaging portions 29 are provided on the rear side of the exterior body 15 and on the left and right sides. As shown in FIGS. 3 and 4, a stepped portion 40 as a longitudinal portion parallel to the longitudinal direction of the exterior body 15 is formed behind the exterior body 15. Further, on the left and right sides of the exterior body 15, as shown in FIG. 2 and FIG. 5, a step portion 42 as a longitudinal portion extending parallel to the longitudinal direction (longitudinal direction of the inner cylinder 13), and the step portion 42 are continuous. An expanded portion 44 is formed as an inclined portion that expands upward.

  The support bracket 12 is always urged in a direction in which the support bracket 12 is accommodated in the holding portion 22 by a spring member (not shown) provided in an operation mechanism 50 described later. The support bracket 12 is accommodated in the holding portion 22 such that the widened portion 44 of the exterior body 15 abuts on the inclined surface on the front side (with respect to the vehicle body) of the widened portion 36 of the holding portion 22. That is, when the support bracket 12 is housed in the holding portion 22 by a spring member (not shown), the front and rear surfaces of the support bracket 12 are in contact with the upper protrusion 23 and the lower protrusion 25. The spread part 44 abuts on the inclined surface in front of the spread part 36. Then, the support bracket 12 is subjected to a force that is pulled downward in the direction along the inclination of the widened portion 36, that is, obliquely rearward, but the rear surface of the support bracket 12 abuts on the upper protrusion 23 and the front surface of the support bracket 12 is lowered. Since the support bracket 12 abuts on the side protrusion 25, the support bracket 12 is held in the holding portion 22 without rattling in both the front-rear direction and the vertical direction.

  The operating mechanism 50 includes a pair of sector gears 52, and one sector gear 52 is connected to one end of a metal strand 134 of the wire 130, and is connected to the wire driving mechanism 6. Each sector gear 52 has a connection pin 54, and the connection pin 54 passes through the connection hole 21 of the connection plate 20. When the sector gear 52 rotates, the connection plate 20 moves up and down via the connection pin 54. In addition, the structure of the action | operation mechanism 50 is not restricted to the said structure.

  The wire drive mechanism 6 includes a link mechanism bent in a dogleg shape. When pressure is applied from the front of the vehicle, the bent portion of the link mechanism is pressed and deformed into a flat shape, and the wire 130 connected to one end of the link mechanism. The metal stranded wire 134 is pulled.

  Next, the effect | action of the headrest tilting apparatus 2 mentioned above is demonstrated.

  The headrest 3 is attached to the upper portion of the vehicle seat 100 by inserting a stay into the headrest driving mechanism 4. In the headrest drive mechanism 4, as shown in FIG. 6, the support bracket 12 is housed in the holding portion 22 and the like, the first engagement portion 27 and the second engagement portion 29 are engaged, and the headrest 3 is for the vehicle. It is securely fixed to the seat 100 and appropriately holds the head of the occupant during vehicle operation.

  Then, with the passenger seated on the vehicle seat 100, for example, when the vehicle collides, the passenger's back is pressed against the seat back 104. Then, the wire drive mechanism 6 operates to pull the metal strand 134 of the wire 130, the sector gear 52 is rotated by the tension of the wire 130, and the connecting plate 20 is instantaneously moved upward.

  The state from the normal state until the connecting plate 20 moves upward and the support bracket 12 tilts is shown in FIGS. First, as shown in FIG. 6, when the support bracket 12 is accommodated in the holding portion 22, the first engagement portion 27 and the second engagement portion 29 engage with each other as described above. The headrest 3 is securely fixed to the vehicle seat 100.

  When the support bracket 12 moves slightly upward, the engagement of the first engagement portion 27 and the second engagement portion 29 is released. As shown in FIG. 7, the guide cam 9 comes out from the upper end of the holding section 22, and the rear cam 11 comes into contact with the upper projection 23 in a state where the lower projection 25 is in contact with the front surface of the support bracket 12. . As a result, the support bracket 12 is tilted forward of the vehicle.

  Since the rear cam 11 and the upper protrusion 23, and the front surface and the lower protrusion 25 of the support bracket 12 are in contact with each other until the support bracket 12 is raised to the uppermost position, the support bracket 12 is continuously moved forward. Tilted. FIG. 8 shows a state where the support bracket 12 is raised to the uppermost position. As shown in the figure, the support bracket 12 has a front surface in contact with the upper end of the holding portion 22 and the lower projection 25, and on the rear surface, the rear cam 11 contacts the upper projection 23 and is positioned in front of the vehicle. Inclined greatly toward.

  Further, when the headrest 3 is moved upward and the head hits the headrest 3 and a rearward force is applied to the support bracket 12, the rear cam 11 is moved to the upper protrusion 23 and the front surface of the support bracket 12 is moved. Since each of the lower protrusions 25 is fixed by the frictional resistance of the exterior member 15, the headrest 3 is not pushed downward at any position of the headrest 3, and the head of the occupant can be reliably protected.

  When the force on the support bracket 12 is eliminated, the support bracket 12 is immediately stored in the holding portion 22 by the spring member. Thereby, the headrest 3 is returned to the normal position.

  FIG. 10 shows another example (a second example) of the cam mechanism. In this second example, the support bracket 12 has a guide portion 9 and a front cam 10 on the front surface, and a rear cam 11 on the rear surface. The holding part 22 includes an upper protrusion 23 corresponding to the rear cam 11 and a lower protrusion 25 corresponding to the front cam 10.

  The front cam 10 is formed in the lower part of the guide part 9, and is inclined forward as it goes downward. The rear cam 11 is inclined backward as it goes downward as in the above example, but the inclination is gentler than the above-described example (indicated by a two-dot chain line in the first example).

  The upper protrusion 23 and the lower protrusion 25 are not significantly different from the above example. However, in the holding part 22, the lower part of the upper protrusion 23 extends rearward smaller than the above example (indicated by a two-dot chain line). In addition, the upper part of the lower protrusion 25 extends upward from the above example (same as above) and has a small forward protrusion.

  Also in such a cam mechanism, when the support bracket 12 is moved upward by the operating portion 50, the support bracket 12 is moved by the action of the upper protrusion 23 and the lower protrusion 25 and the rear cam 11 and the front cam 10. Tilt forward. Compared with the above example, the holding force is improved in the second example because the upper end edge 38 is located above. Further, the thickness of the holding portion 22 in the front-rear direction is reduced.

  FIG. 11 shows a third example of the cam mechanism. In this third example, the support bracket 12 has a front cam 10 on the front surface and a flat rear surface. The holding portion 22 includes an upper protrusion 23 and a lower protrusion 25 corresponding to the front cam 10.

  The front cam 10 is at the lower part of the support bracket 12 and is inclined forward (in comparison with the first example indicated by the two-dot chain line) as it goes downward.

  The upper protrusion 23 and the lower protrusion 25 are not significantly different from those of the first example. In the holding part 22, the lower part of the upper protrusion 23 extends rearward in the first example (indicated by a two-dot chain line). ) And the second example, and in the upper part of the lower protrusion 25, the upper end edge 38 is positioned higher.

  Also in this cam mechanism, when the support bracket 12 is moved upward by the operating portion 50, the support bracket 12 is acted by the action of the upper protrusion 23 and the rear surface of the support bracket 12 and the lower protrusion 25 and the front cam 10. Is tilted forward. Compared to the above example, the third example has a smaller rearward protrusion.

  Furthermore, in any example, when a backward force is applied to the headrest 3, the cam mechanism is locked, the support bracket 12 is held by the holding portion 22, and the headrest 3 does not return.

  Note that the stepless lock may be realized by deformation regardless of the setting of the friction coefficient. That is, due to the load F from the head, the exterior body 15 is deformed at the contact points a and b, that is, at the contact portion between the upper projection 23 and the lower projection 25 and the exterior body 15, and the upper projection 23 and the lower projection You may comprise so that the part 25 may bite.

  That is, the upper protrusion 23 and the lower protrusion 25 are formed as a substantially semicircular diaphragm-shaped portion made of an iron member, and are in line contact with the resin-made exterior body 15. When vertical stress is applied by the load F from the pressure, the pressure increases. Thereby, the surface of the exterior body 15 is easily locally deformed, the upper protrusion 23 and the lower protrusion 25 made of an iron member are engaged with each other, and resistance against the return direction of the headrest 3 is obtained. Even if comprised in this way, a reliable stepless lock mechanism is realizable similarly to the case where frictional resistance was utilized.

The perspective view which shows one Embodiment of the headrest drive mechanism concerning this invention. The perspective view which shows a support bracket. The perspective view which shows a support bracket. The partial back view which shows the headrest drive mechanism of FIG. The partial side view which shows the headrest drive mechanism of FIG. Sectional drawing which shows a holding | maintenance part. Sectional drawing which shows a holding | maintenance part. Sectional drawing which shows a holding | maintenance part. The fragmentary perspective view which shows a wire. The partial rear view which shows the other example of a headrest drive mechanism. The partial side view which shows the other example of a headrest drive mechanism. The perspective view which shows the whole headrest tilting apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Headrest tilting device 3 ... Headrest 4 ... Headrest drive mechanism 6 ... Wire drive mechanism 9 ... Guide part 10 ... Front side cam 11 ... Rear side cam 12 ... Support bracket 14 ... Headrest support 22, 24 ... Holding part 23 ... Upper side protrusion DESCRIPTION OF SYMBOLS 25 ... Lower side protrusion 27 ... 1st engaging part 29 ... 2nd engaging part 50 ... Actuation mechanism 100 ... Vehicle seat 104 ... Seat back

Claims (8)

A headrest driving portion provided on the top of the vehicle seat back, a wire drive unit provided in the lower portion of the seat back, made of the tension transmission member connecting the wire drive unit and the headrest drive unit, the pressure from the passenger In the headrest tilting device that tilts the receiving headrest forward of the vehicle,
The headrest drive unit includes a support bracket to which the headrest is attached, a holding unit that holds the support bracket slidably in the vertical direction, and an operation unit that moves the support bracket upward.
A protrusion projecting inside the holding part is provided on the upper part of the wall after the holding part (with respect to the vehicle),
Forming a cam crest corresponding to the protrusion on the support bracket ,
When the coefficient of friction between the protrusion and the cam peak is set to a predetermined value or more and the headrest is pressed by the head of an occupant, the cam peak is moved to the protrusion by the frictional resistance between the protrusion and the cam peak. Is a headrest tilting device characterized in that the headrest is tilted at a position when the headrest is pressed .   The headrest tilting device according to claim 1, wherein a protrusion projecting inward of the holding portion is provided in a lower part of the wall in front of the holding portion (with respect to the vehicle).   The headrest tilting device according to claim 2, wherein the cam crest is formed on both a front portion and a rear portion of the support bracket.   The headrest tilting device according to claim 3, wherein one of the front and rear cam peaks of the support bracket is formed flat.   The cam mountain is made of a deformable material, and when the headrest is pressed by a passenger's head, the cam mountain is deformed, and the cam mountain is fixed to the protrusion at a position when the headrest is pressed. The headrest tilting device according to any one of claims 1 to 4.   6. The support bracket according to claim 1, further comprising: a spring member, wherein the support bracket is housed in the front holding portion by the spring member when the pressure on the headrest by the head of an occupant is eliminated. The described headrest tilting device. The holding portion includes an inclined portion that is rearwardly lowered at an upper portion of at least one of the left and right sides (with respect to the vehicle) of the holding portion .
The support bracket includes an abutting portion corresponding to the inclined portion of the rear downward at an upper portion of the support bracket ,
When the support bracket is housed in the holding portion, the front and rear surfaces of the support bracket are in contact with the inner surface of the holding portion, respectively , and the contact portion is in contact with the inclined portion that is lowered rearward. The headrest tilting device according to any one of claims 1 to 6. An opening part that expands upward is formed on at least one of the left and right sides (with respect to the vehicle) of the upper end of the holding part, and is formed in parallel with the longitudinal direction of the holding part. Forming a first engaging portion made of a longitudinal portion by a notch ,
On top of the support bracket, and an open flared portion that expansively opened upward, continuously to the open flared portion, the second engaging portion comprising a parallel-formed longitudinal portions along the longitudinal direction of the holding portion The step portion is formed to face the first engagement portion,
When the support bracket is housed in the holding portion, the front and rear surfaces of the support bracket abut against the inner surface of the holding portion, and the spread portion of the second engaging portion is the first engaging portion. The headrest tilting device according to any one of claims 1 to 6, wherein the headrest tilting device is brought into contact with an inclined surface in front of the spreading portion .

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