LOCKING DEVICE FOR AN ADJUSTABLE HEADREST

DESCRIPTION

Technical Field

The present invention relates to a locking device for a height-adjustable headrest, particularly for a motor vehicle seat. The invention enables a user to adjust the height of the headrest vertically relative to the backrest of the seat by manually raising or lowering the headrest without actuating any release mechanism.

Background Art

The headrest of a motor vehicle seat is usually attached to the backrest of the seat and held in position by means of two parallel anchor rods extending from the bottom of the headrest cushion which are inserted into corresponding parallel cylindrical sleeves housed within the inner frame of the backrest. This enables a user to adjust the height of the headrest vertically relative to the backrest of the seat by manually raising or lowering the headrest.

To prevent the headrest from being inadvertently raised or lowered, a mechanism comprising a locking device which is housed within the inner frame of the backrest and connected to an external release button located between the top of the backrest and the headrest, is commonly employed.

Such locking device comprises a releasable latch, which is designed to engage with channels aligned longitudinally along the shaft of one of the anchor rods of the headrest. The channels are designed to ensure that the latch engages firmly with a channel, thereby restricting movement of the anchor rods and preventing the headrest from being lowered without the latch being disengaged from the channel.

To lower the headrest, a user is required to disengage the latch from a channel by manually actuating a release button, usually located between the top of the backrest and the headrest, which causes the latch to be disengaged from the channel, thereby permitting movement of the anchor rods within the cylindrical sleeves.

Such a locking device requires a user to use both hands to adjust the height of the headrest, one to actuate the release button and the other to adjust the height of the headrest. In contemporary designs of headrests, which are intended to blend the headrest with the backrest of the seat to achieve a more ergonomic

5 seat, the external release button for the locking device is only accessible to a user from behind the backrest of the seat. This poses an inconvenience to the user as the user is required to turn around whilst seated or leave the seat entirely in order to actuate the release button. In a moving vehicle, such as a bus, this poses not only a risk to the safety of the user, but may also cause inconvenience

-J O and discomfort to a passenger seated behind the user. Even in contemporary headrest designs, a user is still required to use both hands to adjust the height of the headrest.

For this reason, there is a need for headrests of motor vehicle seats to be height- adjustable by a user manually with a single hand and without requiring the user to ^ g actuate any release mechanism.

Disclosure of Invention

The present invention discloses a locking device for a height-adjustable headrest for a motor vehicle seat, wherein it is an object of this invention to provide for a simple, convenient, safe and effective mechanism to vertically adjust the height of 20 a headrest.

The invention provides for a novel means of locking a headrest in position by securing the anchor rods (5) extending from the bottom of the headrest cushion by means of a locking device comprising a bullet latch (1), a compression spring (2) and a set screw (3).

25 Also provided is a barrel (4) fitted to one of a pair of parallel cylindrical sleeves (8) housed within the inner frame of the backrest of the seat, which barrel (4) houses the bullet latch (1 ), compression spring (2) and set screw (3).

Also provided are a pair of cylindrical anchor rods (5) extending from the bottom of the headrest cushion, wherein one of the anchor rods is characterised by 30 detents (6) aligned longitudinally along its shaft, which detents (6) correspond diametrically to the head of the bullet latch (1 ).

To secure the headrest to the inner frame of the backrest of the seat, the anchor rods (5) are inserted into free sleeves (7), which are in turn inserted into the cylindrical sleeves (8) and the anchor rods (5) are locked in position by means of the bullet latch (1 ) engaging with a detent (6) along the shaft of an anchor rod (5). The compression spring (2) prevents the bullet latch (1 ) from being disengaged from a detent (6) and the resistance of said compression spring (2) can be adjusted manually by tightening a set screw (3) to achieve the desired degree of resistance to prevent the headrest from being raised or lowered inadvertently.

It is a feature of this invention that it enables the height of the headrest to be adjusted vertically relative to the backrest of the seat without actuating any release mechanism.

It is another feature of this invention that it enables the vertical adjustment of the headrest to be effected by a user using a single hand.

It is an advantage of this invention that its use and effectiveness is not dependent on or affected by the design of the headrest cushion.

It is another object of this invention to provide for a locking device for a height- adjustable headrest for a vehicle seat which is inexpensive to manufacture, facile in assemblage and carefree of maintenance.

Brief Description of Drawings

The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings, wherein :

Fig. 1 shows a partial cross-sectional view of the inner frame of a backrest of a motor vehicle seat depicting the anchor rods (5) which extend from the bottom of the headrest cushion inserted into the free sleeves (7), which are in turn inserted into the cylindrical sleeves (8) housed within the inner frame of the backrest and locked in position by means of the invention.

Fig. 2 shows an enlarged partial cross-sectional view of one of the anchor rods (5) inserted into a cylindrical sleeve (8) and depicting the invention in the locked position, whereby the bullet latch (1) is engaged with a detent (6).

Fig. 3 shows an enlarged partial cross-sectional view of one of the anchor rods (5) inserted into a cylindrical sleeve (8) and depicting the invention in the unlocked position, whereby the bullet latch (1 ) is disengaged from a detent (6).

Fig. 4 shows a perspective view of the anchor rods (5) housed within the free sleeves (7), which are in turn inserted into the cylindrical sleeves (8), and depicts the barrel (4) fitted onto one of the cylindrical sleeves (8). The invention is housed within the barrel (4) and is not visible from the drawing.

Best Mode for Carrying Out bf Invention

Fig. 1 shows a cross-sectional front view of the inner frame of a backrest of a conventional motor vehicle seat, wherein a pair of cylindrical anchor rods (5) which extend from the bottom of the headrest cushion are inserted into a pair of free sleeves (7). The free sleeves (7) aid in the smooth vertical movement of the anchor rods (5) relative to the backrest of the vehicle seat. The free sleeves (7) are in turn inserted into corresponding parallel cylindrical sleeves (8) housed within and forming part of the inner frame of the backrest.

As can also be seen from Fig. 1 , the locking device, comprising a bullet latch (1 ), compression spring (2) and set screw (3), is housed and secured within a barrel (4), which is fitted to one of the cylindrical sleeves (8). The barrel (4) may be fitted to a cylindrical sleeve (8) in a number of ways, for example by means of welding or riveting the barrel (4) to the cylindrical sleeve (8).

As can be seen from Fig. 2, the shaft of the anchor rod (5) depicted therein is characterised by detents (6), which are aligned longitudinally along its shaft. The detents (6) may be applied to the shaft of an anchor rod (5) by means of a metal stamping or machining process.

The detents (6) are intended to correspond diametrically with the head of the bullet latch (1 ) such that when the anchor rods (5) are inserted into the free sleeves (7), as shown in Fig. 1 , the bullet latch (1 ) engages with a detent (6) on the shaft of an anchor rod (5), as shown in Fig. 2, thus locking the anchor rod (5) in position.

The detents (6) are aligned longitudinally along the shaft of an anchor rod (5) to enable the anchor rod (5) to be locked in position at different levels, thus enabling the height of the headrest to be adjusted vertically. Fig. 3, which depicts the invention in the unlocked position, shows how the position of an anchor rod (5) may be adjusted vertically by disengaging the bullet latch (1 ) from a detent (6) and engaging it with another detent (6), either at a higher or lower level along the shaft of the anchor rod (5).

The detents (6) are applied to the shaft of only one of the anchor rods (5) of the headrest as this is adequate to secure the anchor rods (5) in position and prevent vertical movement of the anchor rods (5). However, this does not preclude the detents (6) from being applied to the shafts of both anchor rods (5) to achieve a greater degree of resistance, if this is desired.

The compression spring (2) prevents the bullet latch (1 ) from being disengaged from a detent (6), and the degree of resistance of the compression spring (2) can be adjusted manually by means of a set screw (3) to achieve the desired degree of resistance. The ideal degree of resistance to enable a user to adjust the height of the headrest with a single hand and without actuating any separate release mechanism, is between 5kg to 8kg of force. This degree of resistance also ensures that the bullet latch (1 ) is not disengaged from a detent (6) inadvertently by a user. The desired degree of resistance can also be achieved by alternative means, for example by utilising set screws of different lengths or by utilising compression springs with different degrees of resistance.

The head of the bullet latch (1) and the detents (6) along the shaft of the anchor rod (5) are diametrically correspondent to facilitate engagement and disengagement of the bullet latch (1 ) with a detent (6). The circular head of the bullet latch (1 ) also minimises friction between the bullet latch (1 ) and the shaft of the anchor rod (5), thus enabling the bullet latch (1 ) to be moved easily from one detent (6) to another detent (6) along the shaft of the anchor rod (5).

Industrial Applicability

The use of the present invention as disclosed is not limited to a locking device for a height-adjustable headrest of a motor vehicle seat. The present invention can also be applied in a multitude of components, including without limitation other

components of a vehicle or aircraft seat such as adjustable arm rests and adjustable foot rests, wherein the height or length, as the case may be, of such components is adjustable and where a locking device is utilised to secure such components in position. The present invention can also be applied as a locking mechanism to secure optional accessories for such seats, such as meal trays. In general terms, the invention is not limited to the illustrative embodiments which have been shown above, but can be freely modified within the scope of the following patent claims.