JPH03118007A - Forward/backward position adjusting device for headrest - Google Patents

Abstract

PURPOSE:To obtain an operating device utilizing a non-stage adjusting type brake, and to always operate satisfactorily and surely by constituting a fixed regular circular brake drum, and a regular circular disk of a small diameter fitted loosely to an operating shaft, and also, provided in an eccentric state in the drum. CONSTITUTION:When an operating dial 21 is rotated by a manual operation, and an operating shaft 19 is rotated counterclockwise, since the left/right width of an operating plate 33 is formed so as to be narrower than the left/right width of a fitting groove 36 of a regular circular disk 34, in the beginning, only the operating plate 33 runs idle, and an engaging projection 27 of the operating plate 33 abuts on a moving side engaging surface 48 of a right brake block 46. When the operating plate 33 rotates counterclock, since a clearance is formed between a lock projection 57 and lock side engaging surfaces 50, 51 of the left and the right brake blocks 46, 47, the clearance becomes a recess, and only the right brake block 46 is rotated counterclockwise without rotating an eccentric regular circular disk 34. Accordingly, a lock state of the right brake block 46 is released.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides
! This is related to the i-device.

(Prior art) In the conventionally known Japanese Utility Model Application Publication No. 59-162053, the reaction force of a coil spring press-fitted into the inside of a fixed drum is used.
This document describes a headrest operating device that stops the operating shaft from reversing due to the load from the headrest.

Further, in Japanese Utility Model Application Publication No. 61-60855, an operating shaft perpendicular to the center of a perfect circular brake drum is provided in a freely rotatable manner, and an elliptical disk having a smaller diameter than the inner diameter of the brake drum is provided inside the brake drum. and the operating shaft is loosely fitted in the center of the elliptical disc, between the outer circumferential surface of the regular circular disk and the inner circumferential surface of the brake drum.

A narrow part, a wide part, and a space part whose width gradually becomes wider from the narrow part to the wide part are provided, and the narrow part and the wide part are left in the space part and have the same shape as the space part. A continuously adjustable friction brake device is described in which left and right brake blocks are provided, and an engaging protrusion at the tip of an operating plate fixed to the operating shaft is provided in the narrow portion.

(Problems to be Solved by the Invention) Among the above-mentioned known examples, the former has a structure that prevents reversal by using the reaction force of a coil spring press-fitted inside the fixed drum, so the connection between the spring and the fixed drum is It cannot withstand loads greater than the frictional force.

Furthermore, since the spring was installed inside the drum, assembly was troublesome.

Furthermore, since the latter adopts a structure in which an elliptical disc is provided within a perfectly circular brake drum, a total of four left and right brake blocks are used. Therefore,
Not only is it unavoidable that the structure becomes complex, but also
Two of the left and right brake blocks have a structure that is pushed by springs, so the loosening action of the brake blocks is not reliable, and as a result, adjustment can sometimes be difficult.

In addition, the spring may become permanently deformed due to long-term use.
Locks are also uncertain.

(Objective of the Invention) Accordingly, the present invention provides an operating device that utilizes a stepless m-type brake with two left and right brake blocks, which always operates well and reliably.

(Means for Solving the Problems) Therefore, the present invention includes a stay 6 having a pair of legs 7 that are long in the vertical direction, and a group of 13 engagement holes fixed to the stay 6 in the front and rear directions on both left and right sides. A sub-frame 5, pinion gears that engage with the engagement holes 13, a shaft 11 to which the pinion gear 2 is fixed, an operating device 18 that rotates the shirt H1, and a shaft 11 that is attached to the shirt 11 side. Side frame 17 that moves back and forth with
．． 17 and a main frame, the operating device 18 includes an operating shaft 19 attached to one end of the shirt 11, a fixed circular brake drum 24 provided on the outer periphery of the operating shaft 19, and a fixed circular brake drum 24 provided on the outer periphery of the operating shaft 19. A small-diameter regular circular disc 34 loosely fitted onto the operating shaft 19 and eccentrically provided within the drum 24, and narrow portions 42, 43 on both sides of the lower part formed between the brake drum 24 and the regular circular disc. and the wide part on both sides of the top, 6, and the side space between them, 41, and the side space cut, 41
left and right brake blocks 47 provided therein; an operating plate having an engaging protrusion support fixed to the operating shaft 19 and engaged between the narrow width portions 42 and 43; and an operating plate that is loosely fitted to the operating shaft 19. and an engaging tube (material) that is fixed integrally or separately to the lock plate 56 and rotates integrally with the shirt 11, and an operating dial 21 that is fixed to the end of the operating shaft 19. The front and back position of the headrest can be adjusted.

And, inside the wide part shrine 6 are the left and right brake blocks 4.
6.47 is a headrest rear position adjustment device provided with an elastic member area that presses toward the narrow portion C, 43.

(Example) To explain an example of the present invention with the drawings, l is a vehicle seat (regardless of whether it is a front seat or a rear seat), and 2 is the vehicle seat 1.
In FIG. 2, 5 is a subframe provided in the headrest 3, and the lower surface of the subframe 5 has an upper part of the stay 6. are fixed, and the pair of legs 7.7 of the stay 6 are inserted into a pair of support tubes provided in the childcare seat 2 so as to be vertically adjustable.

The left and right side plates 8, 8 of the sub-frame 5 are bent in the middle in the vertical direction so as to protrude outward over the entire width, forming a bent portion 9°9 having a shape when viewed from the front (FIG. 2). 0M
, a sliding member 10.1 is provided in the curved portion 9.9 so as to be slidable back and forth.
0 into each other. The sliding member 10.10 is formed of synthetic resin or the like into a rectangular prism shape that is elongated in the front-rear direction, and its upper and lower surfaces and outer surface are brought into sliding contact with the inner surface of the bent portion 9. Both left and right end portions of a shaft 11 in the left and right direction are freely rotatably mounted in the intermediate portions of the sliding members io and 10 in the front and back direction. Pinion gears 1.12 and 12 are fixed to the inner side of each sliding member 10 of the shaft 11, respectively.
is engaged with any one of a group of 13 engagement holes formed at predetermined intervals on the lower surface of the bent portion 9.9.

A side frame 17.17 is attached to the outside of the side plate 8.8 of the subframe 5 so as to be movable back and forth with respect to the subframe 5. That is, the side plate 14.14 of the bent portion 9°9
A long hole 15.15 is formed in the front and back direction, and the long hole 1
The sliding member 10 and the 01 part frame 17 are fixed by caulking with a pin 16.16 passing through the side plate 8.8 so that they move together. 20 is a main frame attached between the side frames 17 and 17. Note that the side frames 17.17 and the main frame may be formed integrally, but this is not the gist of the present invention.

An operating shaft 0 of an operating device 18, which will be described later, is attached to one end of the shaft 11, and the shaft 11 is rotated by the operating shaft 19 to engage the pinion gear 12 and the engagement hole 1.
By the action of 3, the sliding member 10.10 is moved back and forth,
The side frame 17 and the main frame π are moved back and forth relative to the subframe 5 to adjust the front and back position of the headrest 3.

Note that it is also possible to change the moving direction of the headrest 3 by changing the shapes of the bent portion 9.9 and the sliding member 10.10.

That is, when the bent portion 9 is formed to be inclined lower toward the front side when viewed from the side, the headrest 3 can be moved diagonally forward.

Thus, the operating device I8 has an operating dial 21 attached to the outer end of the operating shaft 19, and although the operating cuff can be rotated from the operating dial 21 side, it is locked and cannot be rotated from the pinion galley side. It locks steplessly.

That is, although a load is applied to the headrest 3 to move it rearward, this load prevents the pinion gear l from reversing, thereby holding the headrest 3 at the m-node position.

In FIG. 2, η is the case of the operating device 18, which is made of a desired material such as metal or synthetic resin. and a flange δ connected to the mouth edge of the drum 24, and the flange 3 is connected to the side frame 1.
7 by known means such as bolts or welding.

A mounting hole is formed in the left and right direction in the center of the bottom plate n, and the serration groove shaft part n formed at the outer end of the operating cuff is rotatably inserted into the mounting hole 3, The operation dial 21 is fixed to the serration groove shaft portion η protruding outwardly by a pin 28. 29 is a bent portion formed in the center of the operation dial 21, I is a through hole formed in the space of the recess into which the bolt 2B is inserted, and 31 is a lid member fitted into the recess 3.

An operating plate 33 is provided on the inner side of the bottom plate B of the operating shaft 19 and has an engaging protrusion that protrudes in the radial direction and whose tip is bent parallel to the operating shaft 19. The operating plate 33 rotates within the brake drum 24. (Fig. 2, Fig. 5).

An eccentric regular circular disk is attached to the inside of the operation plate 33. The eccentric circular disk U is formed into a circular shape by a member having thickness on the left and right sides (FIGS. 2 and 4).

Eccentric circular disc At an eccentric position away from the center of the winnow,
A mounting hole is formed in the left and right direction (FIG. 2), and the mounting hole is inserted into the operating cuff freely only by rotation.

A fitting groove is formed on the outer surface of the eccentric circular disk in a direction passing through the center of the disk 34 and the mounting hole, and the operating plate is fitted into the fitting groove. The lateral width of the fitting 8I36 when viewed from the side is wider than the true lateral width of the operation plate (Fig. 7), so that when the operation plate is rotated, the operation plate is initially operated without rotating the disk blades). When only 33 rotates idly and then rotates a little, the left and right sides of the operating plate come into contact with the wall g of the fitting groove I, rotating the eccentric circular disk A.

Therefore, when the eccentric regular circular disk is fitted into the brake drum 24, there are gaps between the outer circumferential surface of the disk and the inner circumferential surface of the drum 24 on the left and right sides when viewed from the side. A symmetrical side space cut 41 is formed (
Figure 7).

As mentioned above, the eccentric circular disk has the mounting hole formed at an eccentric position off the center, so that the side space 41 is located on both sides of the lower side as shown in FIG. It is formed into narrow narrow parts 42, 43, and the upper sides are formed into wide members 45 which gradually become wider.

A pair of left and right brake blocks 47 are movably fitted into the side space openings 41 (FIG. 8).

The left and right brake blocks 47 are the side space class,
41, and as shown in Fig. 8, it is formed in a shape that is narrow at the bottom and becomes thicker toward the upper side, and a movable side engagement surface, a leopard, is formed on the end face of each narrow width side. (Fig. 2), and the thick side end face has a lock side engagement surface, 51
(Figure 2).

The outer peripheral surfaces of the left and right brake blocks 47 are formed into arcuate surfaces centered on the axis of the operating cuff.

The inner circumferences 55 of the left and right brake blocks 47 are respectively formed into arcuate surfaces concentric with the center of the circular disc U at predetermined positions.

Therefore, the inner peripheral surface of the left and right brake blocks 47, I, is the outer peripheral surface of the eccentric regular circular disk, and the outer peripheral surfaces 52 and 53 of the left and right brake blocks 47 are the inner peripheral surface of the brake drum 24. They move (rotate) in close contact with each other to prevent wobbling.

The engagement protrusion of the operation plate 33 is located between the movable side engagement surface blades formed at the lower part of the left and right brake blocks 47, and the left and right brake blocks 47
Upper lock-side engagement surface (equipment) of 7, 5! A +7 protrusion 57 of the lock plate 56 is positioned between them.

Row 7 protrusion 57 and the lock side engagement surface (material), 51
A gap is formed between each of the engaging protrusions (Fig. 8). When the brake block rotates, the gap acts as an escape, and only the left and right brake blocks 47 are moved, releasing the locked state.

The lock plate 56 engages the engagement teeth 61 of the engagement tube with the engagement groove 8 of the attachment hole 8 formed at its base. The retaining cylinder (material) may be formed integrally with the lock plate 56, and the engaging teeth 61 between the engaging parts are connected to the side frame 17.
Insert it into the shirt 11 through the elongated hole 15. Serrations [62 are formed on the inner circumferential surface of the shirt) 11, and the engaging teeth 61 are engaged with the serration grooves, and the lock plate group is rotated to close the shirt) 11. Rotate the binion galley and move the headrest 3 back and forth. The inner end of the handle 19 is rotatably inserted into the engagement tube.

Therefore, if the operating shaft 9 and the lock plate housing are in a loosely fitted state, and if the lock plate 56 and the shirt 11 are of a 4IN structure that rotates integrally, the engaging cylinder ring will be attached to the shaft 11.
It may be placed on the side.

Thus, the elastic member 8 is fitted between the lock-side engaging surfaces 51 of the left and right brake blocks 47, and the elastic members are locked with the lock-side engaging surfaces using synthetic resin or the like. It is formed wider than the distance from the side engagement surface 51, and elastically protrudes from both the lock side engagement surface 51 so as to press the left and right brake blocks 46, 47 toward the narrow width portion 43 side. come into contact with

8 is a spring provided between the main frame 4 and the subframe 5, and 65 is an undercover.

(effect) Next, we will discuss the effect.

The present invention has the above-mentioned configuration, and the stay 6 is attached to the subframe 5.
The upper part of the shirt 11 is fixed, the left and right ends of the shirt 11 are mounted on the sliding member 10.10, the sliding member 10.10 is fitted into the bent part 9.9 of the sub-frame 5, and each sliding The member 10 and each side frame 17 are sandwiched between the subframe 5 and the bin 16.
Fix it by.

Next, the main frame is attached to the side frames 17, 17, springs are attached between the main frame and the subframe 5, and undercover wings are attached from below the stay 6.

Next, the operating shaft 19 is inserted into the case η from the inside, the eccentric front gate type disc is inserted into the operating cuff in the brake drum 24, and the left and right brake blocks 19 are inserted into the side space 41 in the brake drum 24. .
Shaft facing! ! The serration groove of the engaging tube (
When the retaining teeth 61 of the case η are secured and fixed, and the flange 6 of the case η is secured to the side frame 17, the assembly of the operating device 18 is completed, and the outer periphery of the side frame 17 and the main frame The cushion material is attached, the outer periphery of the cushion material is surrounded by a skin, and the operation dial 21 is fixed to the serration groove shaft portion H of the operation shaft 19.

When the operating dial 21 is manually rotated and the operating shaft 19 is rotated to the left as shown in FIG.
I! Since the width is narrower than the left and right width of 136, only the operation plate 33 rotates idly at first, and the operation play) 3
The engaging protrusion n of No. 3 comes into contact with the movable side engaging surface mallet of the right brake block.

Furthermore, when the operation play) 33 is rotated to the left, the lock protrusion 5
7 and the aforementioned left and right brake blocks, 47's lock side engagement surfaces, 5! Since a gap is formed between the two, the gap acts as a relief, and only the right brake block can be rotated to the left without rotating the eccentric circular disk U (FIG. 9). Therefore, the locked state of the right brake block is released.

When the right brake block 6 rotates to the left, the lock-side engagement surface at the top of the right brake block contacts the elastic base, and when the right brake block further rotates, the elastic member area contacts the other left brake block. , press the lock-side engaging surface 51 of the lever 47.

At the same time, the side surface of the operation plate 33 comes into contact with the wall surface of the fitting groove violet of the eccentric regular circular disk.

Rotate the disc to the left.

When the operating shaft 19 rotates to the left in this way, the side space portion into which the right brake block is fitted is formed into a wide portion that becomes wider in the direction in which the right brake block rotates. From there, the right brake block moves to a position where it becomes loose.

On the other hand, the left brake block 47 is apparently pushed toward the upper narrow part C by the right brake block through the elastic part, but the movement is faster than the movement of the left brake block 47, and the side surface of the operating plate blade is pushed. Since the eccentric circular disc U rotates to the left, the left brake block 47 also relatively moves to a slack position in the direction of the wide part 6 where the width becomes wider, and the right brake block 4G and
The left brake block 47 and the eccentric circular disk rotate to the left together.

Therefore, when the operating shaft 19 rotates to the left, the right brake block 47, the left brake block 47, and the eccentric circular disc U rotate together, and this rotation causes the lock plate 56 to rotate. The rotation is as follows: Engagement groove μs of lock play) 56 → Engagement cylinder mark distance 1M
61→Transmitted to the serration groove of shaft 11,
Rotate the shaft 11 to rotate the binion gal,
The rotation of the pinion gear causes the sliding member lO to move forward together with the side frame 17 and the main frame, thereby moving the headrest 3 forward.

Furthermore, when the operating shaft 19 is rotated clockwise using the operating dial 21, the right brake block 47, the left brake block 47, and the eccentric regular circular disk rotate clockwise together for the same reason as described above. , the sliding member 10 is moved rearward by the rotation of the pinion gear 12, and the headrest 3 is moved rearward and adjusted.

In this case, an elastic part foundation is fitted between the left and right brake blocks, the lock side engaging surfaces (materials) 47, and 51;
Since the left brake block 47 is moved via the elastic part at the same time as the right brake block TS is moved, the rotation of the right brake block TSKUDA, the left brake block 47, and the eccentric regular circular disc is smooth. It is done.

After adjusting the position as described above, when you release your hand from the operation dial 21, the elastic part turns into left and right brake blocks, 47
Since the pressure caused by the rotation is released and it returns to its original size, the elastic part turns into left and right brake blocks, and presses 47 towards the narrow part C, 43, preventing the left and right brake blocks and 47 from wobbling. do.

However, when the head of the 1M rider pushes the headrest 3 backward, the main frame 17, the side frame 17,
A load is applied via the shaft 11 to reverse the rotation of the pinion gear.

Therefore, the pinion gear l attempts to, for example, rotate the lock plate shell clockwise from the state shown in FIG. 8 via the engagement teeth 61 between the engagement parts. The right brake block Tsukuda is pushed in the direction of the narrow part C, and the right brake block Tsukuda is pushed in the direction to rotate the eccentric circular disc winnow to the right.

When a force is applied to the eccentric circular disc in the clockwise direction, the left brake block 47 is pushed in the direction of counterclockwise rotation relative to the eccentric circular disc, and the left brake The block 47 is also pushed in the direction of the narrow part C, and the right brake block, # distribution brake block 47, and the eccentric circular disc jointly apply the brake. , prevents reverse rotation of the pinion gear.

Therefore, the headrest 3 does not move rearward even when subjected to an impact load caused by the seated person.

In this case, the elastic part between the left and right brake blocks, the lock side engaging surfaces 47, and 51 always connects both the lock side engaging surfaces 51 to the left and right brake blocks. Since the lock protrusion 57 is pressed to move to the narrow portion 42.43, the lock protrusion 57 comes into contact with one of the lock-side engaging surfaces 51 of the left and right brake blocks 46.47. When pressed, the left and right brake blocks are formed, and both 47 immediately move to the relatively narrow part 4 as described above.
It can be fitted and locked in directions 2 and 43.

(Effects) The present invention comprises a stay 6 having a pair of legs 7 that are long in the vertical direction, a sub-frame 5 fixed to the stay 6 and having 13 groups of engagement holes arranged in the front and back direction on both left and right sides, and the above-mentioned engagement holes. Matching hole 13
a pinion gear retainer that engages with each other, a shirt 11 to which the pinion gear retainer is fixed, an operating device 18 that rotates the shaft 11, and a side frame 17 that is attached to the shaft 11 side and moves back and forth together with the shirt 11. .1
7 and a main frame, the operating device includes an operating shaft 19 attached to one end of the shaft 11, a fixed regular circular brake drum 24 provided at the outer part of the operating cuff, and the operating device. A small-diameter regular circular disc NU that is loosely fitted into the cuff and eccentrically provided in the drum 24, and narrow portions 4 on both sides of the lower part formed between the brake drum 24 and the regular circular disc U.
2. 43, wide members on both sides of the upper part, 5, side spaces 40 and 41 extending therebetween, left and right brake blocks provided in the side spaces 41, 47, and the operating shaft 19;
An engaging protrusion that is fixed to the narrow portion and engages between the core!
an operating plate) 33 that is loosely fitted onto the operating shaft 19, is fixed integrally or separately to the lock plate 56, and rotates integrally with respect to the shaft 11;
9) and an operation dial 21 fixed to the end of the operation shaft 19.

■ Due to the load applied to the headrest 3, the frame 17 and the frame 11 move backward, and when the pinion gear rotates in the opposite direction, the lock protrusion 57 rotates, and the left and right brake blocks 46, 47 close to the narrow part 42. , because it moves relatively toward 43 and applies the brakes due to the simulated phenomenon.

Can withstand heavy loads.

(2) When assembling the eccentric circular disc U, left and right brake blocks, 47, etc. into the case 24, it is easy to assemble because springs are not used as in the known example.

■ Because it uses an eccentric circular disc, it is small and
Light weight and low cost.

In addition, the left and right brake blocks 6 are located inside the 1 wide bar and 6.
．． 47 is a headrest back-and-forth position adjustment device that is provided with an elastic base that presses toward the center of the narrow part. left brake block 4
7 is moved, the right brake block 47, the left brake block 47, and the eccentric circular disk are rotated smoothly.

■ After adjusting the M position as described above, when you release your hand from the operation dial 21, the elastic member 1 presses the left and right brake blocks 47 toward the narrow parts 42 and 43, causing the left and right brake blocks 47 to wobble. prevent.

■ The lock protrusion 57 is on the left and right brake block 47
If you press one of them, the left and right brake blocks 柘, 47
Both can be immediately fitted and locked in the direction of the narrow parts 42 and 43 relative to each other.

This effect is achieved.

[Brief explanation of drawings]

Fig. 1 is a perspective view of the seat, Fig. 2 is a perspective view of the entire device assembled, Fig. 3 is a perspective view of the main parts assembled, Fig. 4 is a longitudinal front view, and Fig. 5 is a longitudinal front view of the main parts. , FIG. 6 is a cross-sectional plan view of the main part, FIG. 7 is a vertical right side view in a state where the brake block is not fitted, and FIG. 8 is a vertical right side view in a free state. 9 and 10 are vertical right side views in the operating state, and FIG. 11 is a vertical right side view in the locked state. Explanation of symbols l...Vehicle seat, 2...Preamble sheet, 3...
Headrest, 5... Subframe, 6... Stay 7... Leg, 8... Side plate, 9... Bent part, 10...
...Sliding member, 11...Shaft, two...Pinion gear, 13...Engagement hole, 14...Side plate, 15
...Elongated hole, 17...Side frame, 18...Operation device, 19...Operation axis, 20...Main frame, 21...Operation dial, 22...Case,・
・Bottom plate, 24... Brake drum, 3... Flam part, Kyo... Mounting hole, 27... Serration lIt@ part, n
···bolt. n... recess, I... through hole, 31... lid member, di...
...Engagement protrusion, O...Operation plate, A...Eccentric circular disc, 35...Mounting hole, A...Fitting groove, G...Wall surface, (...Outer peripheral surface, 39...Inner peripheral surface, 40
．． 4! ...Side space, 42, invitation...@narrow, weak,
柘...Wide part, catch, 47...brake block, mallet, leopard...moving side engagement surface, (capital), 51...locking side retaining surface, father, 8...outer peripheral surface , -155...inner peripheral surface,
Leap...lock plate, 57...lock protrusion, father...
...Mounting hole, 59...Engagement groove, mark...Engagement tube, 61
...Engaging teeth, Dry...Serration grooves, Fields...Elastic members, Lifts...Springs, 65...Under force Par 1 Figure 7 Figure 7 Figure 1 Procedural corrections spontaneously) Heisei Date of November 1, 1999 1゜ Indication of the incident Patent Application No. 1-256675 Representative Yu Yanagibashi 4゜ Agent 5゜ Date of amendment order Figure 5

Claims (2)

[Claims] (1) A stay 6 having a pair of legs 7 that are long in the vertical direction, and engagement holes 1 fixed to the stay 6 and extending in the front and rear directions on both left and right sides.
A subframe 5 in which three groups are arranged in parallel, pinion gears 12 that engage with the engagement holes 13, a shaft 11 to which the pinion gears 12 are fixed, an operating device 18 that rotates the shaft 11, and a side of the shaft 11. side frames 17, 1 that are attached to the shaft 11 and move back and forth together with the shaft 11;
7 and a main frame 20, the operating device 18 includes an operating shaft 19 attached to one end of the shaft 11, a fixed regular circular brake drum 24 provided on the outer periphery of the operating shaft 19, and a fixed circular brake drum 24 provided on the outer periphery of the operating shaft 19. axis 1
a small-diameter regular circular disc 34 that is loosely fitted into the brake drum 24 and provided eccentrically within the drum 24; and narrow portions 42 and 43 on both sides of the lower part formed between the brake drum 24 and the regular circular disc 34; Wide parts 44 and 45 on both sides of the upper part, side spaces 40 and 41 extending therebetween, and the side spaces 4
Left and right brake blocks 46, 4 provided in 0, 41
7, and the narrow portions 42, 43 fixed to the operating shaft 19.
an operation plate 33 having an engaging protrusion 32 that engages between the
and a lock plate 5 having a lock protrusion 57 that is loosely fitted onto the operating shaft 19 and engaged between the wide parts 44 and 45.
6, and the lock plate 5 loosely fitted onto the operating shaft 19.
A headrest longitudinal position adjustment device comprising an engagement tube 60 that is fixed integrally or separately to the shaft 11 and rotates integrally with the shaft 11, and an operation dial 21 fixed to the end of the operation shaft 19. . (2) In the item of claim 1, the left and right brake blocks 46, 4 are provided in the wide portions 44, 45.
7 toward the narrow width portions 42 and 43.