Adjustment mechanism for a motor vehicle seat, and a seat equipped with such a mechanism

• US 6,808,233 B2
• Filed: 10/22/2002
• Issued: 10/26/2004
• Est. Priority Date: 11/16/2001
• Status: Expired due to Fees

• Current Assignee: Hutchinson (Welltower, Inc.)
• Original Assignee: Hutchinson (Welltower, Inc.)
• Inventors: Mallard, Patrick
• Primary Examiner(s): Nelson, Jr., Milton
• Application Number:
  US10/277,423
• Publication Number:
  US 20040012236A1
• Time in Patent Office: 735 Days
• Field of Search: 297/344.1, 248/429, 74/892.8, 74/391.4
• US Class Current: 297/344.1
• CPC Class Codes: B60N 2/02246 Electric motors therefor
• CPC Class Codes: B60N 2/02253 characterised by the transmission between the electric motor and the seat or seat parts
• CPC Class Codes: B60N 2/0228 Hand-activated mechanical switches B60N2/0229 takes precedence
• CPC Class Codes: B60N 2/0276 reaction to emergency situations, e.g. crash
• CPC Class Codes: B60N 2/067 by linear actuators, e.g. linear screw mechanisms

Abstract

An adjustment mechanism for adjusting a motor vehicle seat comprising a worm screw mounted in a nut which is carried by a rigid base, the worm screw being mounted to rotate relative to the base. A locking piece is mounted on the base so as to be pushed by the nut into an active position in which said locking piece comes into engagement with the worm screw, when a large axial force is transmitted to the worm screw.

Claims

1. An adjustment mechanism for adjusting a motor vehicle seat, said adjustment mechanism comprising a worm screw mounted in a nut which is carried by a rigid base, the worm screw being mounted to rotate relative to the base to cause the screw and the base to move in translation relative to each other along a longitudinal axis, the nut normally being held in a rest position relative to the base, and said nut being mounted on the base with a certain amount of clearance along the longitudinal axis;

wherein said adjustment mechanism further comprises at least one locking piece which is mounted to move relative to the base between firstly a retracted position in which said locking piece does not interfere with the worm screw and secondly at least a first active position in which said locking piece comes into engagement with the worm screw to prevent said worm screw from moving relative to the base;

wherein the nut is adapted to act on the locking piece when said nut is moved at least in a first direction along the longitudinal axis from the rest position of said nut;

and wherein the locking piece is mounted on the base such that the nut moving in said first direction causes said locking piece to move towards its first active position.

2. An adjustment mechanism according to claim 1, in which the nut is made of a plastics material not filled with reinforcing fibers.

3. An adjustment mechanism according to claim 1, in which the nut is adapted to push the locking piece at least in the first direction, and said locking piece has a first abutment surface in contact with a first cam surface belonging to the base, said first abutment surface and said first cam surface being adapted to move the locking piece towards the worm screw when said locking piece is moved by the nut in said first direction.

4. An adjustment mechanism according to claim 3, in which the first cam surface is shaped like a ramp converging towards the worm screw in the first direction, and the first abutment surface of the locking piece is also in the shape of a ramp that is substantially parallel to the first cam surface.

5. An adjustment mechanism according to claim 1, in which the worm screw is provided with at least one helical thread and the locking piece is provided with a first set of teeth adapted to engage in said thread when said locking piece is in its first active position.

6. An adjustment mechanism according to claim 1, in which the base has a rigid cage which surrounds the worm screw and which has two abutment faces disposed on either side of the nut along the longitudinal axis, two flexible buffers being interposed between the nut and respective ones of said abutment faces to urge the nut resiliently into its rest position.

7. An adjustment mechanism according to claim 6, in which the nut is made of a plastics material, and is adapted to deform plastically against said abutment face when the worm screw is subjected to a force that is larger than a limit value along the longitudinal axis, and the locking piece is adapted to press the worm screw against the cage when the nut deforms plastically against said abutment face.

8. An adjustment mechanism according to claim 6, in which:

the nut is further adapted to push the locking piece in a second direction opposite from the first direction, and said locking piece further has a second abutment surface in contact with a second cam surface belonging to the base, said second abutment surface and said second cam surface being adapted to move the locking piece towards a second active position in which said locking piece comes into engagement with the worm screw when said locking piece is moved by the nut in said second direction;

the second cam surface is shaped like a ramp converging towards the worm screw in the second direction and the second abutment surface of the locking piece is also shaped like a ramp that is substantially parallel to the second cam surface;

the locking piece is provided with a second set of teeth adapted to engage in said thread when said locking piece is in its second active position; and

between its first and second sets of teeth, the locking piece has a notch open towards the worm screw and in which a tab belonging to the nut is engaged, with a certain amount of clearance making it possible for the locking piece to move towards the worm screw from its retracted position;

the locking piece being adapted to press the worm screw against the cage when said nut deforms plastically against said abutment face.

9. An adjustment mechanism according to claim 1, further comprising at least one runner designed to enable a motor vehicle seat to be adjusted longitudinally, said runner comprising first and second rails which extend along the longitudinal axis, the first rail being secured to the base, and the worm screw being mounted to rotate on the second rail.

10. A vehicle seat including a seat proper whose longitudinal position can be adjusted by means of an adjustment mechanism according to claim 1.