Chairs and seats – Movable back – Tiltable
Reexamination Certificate
2001-02-26
2004-10-26
Nelson, Jr., Milton (Department: 3636)
Chairs and seats
Movable back
Tiltable
Reexamination Certificate
active
06808235
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims priority to United Kingdom Patent Application No. 0004715.9 filed Feb. 28, 2000 and United Kingdom Patent Application No. 0019201.3 filed Aug. 7, 2000.
BACKGROUND OF THE INVENTION
This invention relates to a method and apparatus for adjusting automotive seat mechanisms and other mechanisms.
Mechanical seat adjustment mechanisms are the subject of a very large number of published patent specifications. Examples of prior seat adjustment mechanism are shown in GB 2,311,094 and GB 2,073,094, although it will be appreciated that there are a large number of other types of seat adjustment mechanisms. There is an endless quest for improvements in such mechanisms in terms of improvements in efficacy and cost effectiveness. The present invention seeks to provide improvements in relation to at least one of these areas.
More specifically, mechanisms for the stepless adjustment of automotive seat backs relative to automotive seat bases are well known. One of the main problem areas in terms of efficacy and cost-effectiveness relates to the fact that such mechanisms need to provide stepless adjustment in combination with the ability to withstand enormous forces arising from automotive impacts leading to seat-belt-transmitted forces having a very large turning moment at the seat pivot. An additional problem relates to backlash which can develop within the seat adjustment mechanisms and in particular in gear type seat adjustment mechanisms. Such backlash results from clearances between the mating mechanical elements which may be required for operation, arise due to inaccuracies in manufacture, or develop due to wear. Backlash within a seat adjustment mechanism is however undesirable in terms of passenger comfort, safety, and also can increase wear on the seat mechanism components.
SUMMARY OF THE INVENTION
The present invention seeks to provide a new design approach to the construction of steplessly adjustable seat (and other) mechanisms, in accordance with the following.
According to the invention there is provided method and apparatus for adjusting automotive seat and other mechanisms as defined in the accompanying claims.
In an embodiment of the invention described below there is provided a method and apparatus in which locking of a pivot mechanism is used, for example, in an automotive seat pivot or related adjustable seat mechanism, and is achieved by the use of a magneto-rheological (MR) or electro-rheological (ER) fluid in association with a displacement-sensitive mechanism whereby the combination is responsive to selective changes in the status of the fluid in accordance with the principle that when the fluid is selectively caused to adopt its rheologically activated status it interacts with the mechanism on account of the volume-sensitive pumping action (as it may be termed) of the latter whereby the mechanism is effectively locked when filled (or sufficiently filled) with such a fluid.
By providing the combination of a selectively rheologically status-changeable fluid in association with a volume-sensitive mechanism (for example having a pumping action), the means is provided for achieving a selective and stepless locking action which is instantly (or at least quickly) changeable from its locking to its unlocking status by mere actuation of a magneto or electro-responsive system and without the need for the conventional mechanical disengagement of pawls from ratchets or friction elements from friction surfaces to which they are locked.
Moreover, the use of MR/ER fluids enables the adoption of mechanisms having only modest levels of manufacturing tolerances (and thus which can be manufactured at correspondingly relatively modest costs), and this is due to the fact that the MR/ER fluids interact with the mechanism in a second and likewise unexpected manner in the sense that the adoption of modest and cost-effective tolerances is offset by the ability of the MR/ER fluids (in their activated condition) to interact with the interstices of the associated mechanism (but only in the volume-sensitive and/or pumping environment) so as to offset what might otherwise be arguably unacceptably low manufacturing standards. The MR/ER fluids also effectively off set and reduce any backlash within the mechanisms do to clearances developing as a result of tolerance variations. In addition as the mechanism wears the tolerance variations increase. The MR/ER fluids are able to compensate for this increase, maintaining the overall standard of the mechanism, and maintaining a secure mechanism with little backlash
Accordingly, it can be seen that the embodiments of the invention offer a system in which a fluid medium having selectively controllable properties which enable those properties to be conveniently and instantly switched from one status to another, is able to perform a function which is, in principle, not within the previously realised operational parameters of such fluids. The present invention's embodiments take no account of previous unpublished proposals for the use of such fluids in damping mechanisms, useful though such functions may be. Conventional damping fluids have no function whatever in relation to the locking of mechanisms, and are likewise of no utility for the purposes of the present invention. The embodiments of the present invention take advantage of the known property of the changeable status of magneto- and electro-rheological fluids, and use this known property in association with a mechanism which is sensitive to (and thus responds differently according to) the changes in those rheological properties which can be selectively commanded by the operator.
As to the mechanisms which, in association with MR and ER fluids can provide the necessary responsiveness to that status change, the following applies. One embodiment of the invention which employs such a mechanism utilises the fluid volume implications inherent in (but previously unappreciated) the meshing relationship between a toothed annular internal periphery gear and a pinion meshing therewith and having a numerical tooth differential as between the two gears whereby the known effect of such a twin gear train is utilised in present seat adjustment mechanisms (for stepless control of the seat back angular position). Such a mechanism requires a high degree of precision manufacture. The tolerances required are fine in order to achieve the necessary absence of backlash in the mechanism when in use.
The present invention in one of its embodiments, uses the previously unrecognised fluid volume implications of this gear train in combination with the status-change selectively available properties of MR and ER fluids to enable such a mechanism to be effective in use without the need for the high degree of precision which has hitherto have been required.
Other related mechanisms exist which can be likewise locked in similar way. Such mechanisms share with the above-mentioned embodiment the following properties including (as previously discussed) volume sensitivity.
Said volume-sensitive mechanism comprise in the embodiments a positive displacement mechanism. Examples of such mechanisms including gear lobe mechanisms, piston mechanisms, and peristaltic mechanisms.
In the embodiments the effect of the positive displacement characteristic of the mechanism is to cause the actual displacement of a specific volume of fluid, such displacement involving, effectively, a fluid coupling from the positive displacement device to, in the embodiments, a fluid flow restriction device whereby the effect of the controllable flow characteristic of the MR or ER fluid effectively interposes a medium allowing (or not) the actual displacement of such fluid by the relative movement of the parts of the positive displacement device driving same.
In the embodiments the positive displaced fluid is able, when the MR/ER fluid has not been caused to adopt its activated non-free flowing condition, to circulate within the mechanism from the zone of displacement to a flow-and-return zone which permit
Jr. Milton Nelson
Lear Corporation
Panagos Bill C.
LandOfFree
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