Beds – With heating or cooling – And means to force air
Reexamination Certificate
1998-07-30
2001-07-24
Luu, Teri Pham (Department: 3627)
Beds
With heating or cooling
And means to force air
C005S421000, C005S652200, C168S039001
Reexamination Certificate
active
06263530
ABSTRACT:
BACKGROUND
1. Field of the Invention
The present invention relates to a cushion, such as for use as a mattress or seat and backrest, for example, which presents an outer surface of selectively variable temperature and apparatus therefor including a heat pump for reducing cushion temperature operating on a Stirling cycle.
2. Description of Related Art
There are many situations in which it is desirable that a cushion, such as a seat and backrest in an automotive vehicle, for example, be selectively cooled or heated for the comfort of someone sitting or resting against the cushion. In the colder climates, it would be desirable, particularly in the winter time, to obtain relatively instant heating of the seat cushions to warm an individual sitting or leaning on them prior to normal actuation of the auto heating system which typically relies upon the engine coolant being brought up to a sufficiently high temperature for satisfactory operation. In warm seasons, these same vehicles which have conventional air conditioning systems that direct cool air directly on the front of passengers and into the vehicle interior generally, undesirably leave those portions of the individual directly facing and contacting the seat and backrest cushions at an undesirably elevated temperature and, in the case of high humidity, this results in even more discomfort for the vehicle occupant. In both situations, warming or cooling, as the case may be, of the cushions themselves will increase the comfort level of the individual.
Because of believed deleterious effect upon the environment, certain of the more efficient chemical materials (e.g., Freon) are being forced into retirement from use in air conditioning systems. At the present time, all other substitute materials known for this purpose do not possess the same high level of efficiency and are, in truth, substantially inferior in normal operation to those being eliminated. Also, there is the increasing problem that future automotive vehicles may be required to operate on less and less power in order to conserve basic fuels as well as reduce harmful byproducts, and this will, of necessity, leave a lesser proportion of available power for use by air conditioning or heating equipment.
In U.S. Pat. No. 5,002,336, by Steve Feher, there is disclosed a seat and backrest especially constructed for being cooled or heated as desired where the heat pump utilized for this purpose is a thermoelectric unit which accomplishes the desired function with a substantially lower energy requirement than is utilized where the full interior of the vehicle is conditioned in accordance with conventional air conditioning techniques. However, even though considered a substantial improvement over other known and conventional techniques, there is still believed to be room for improvement especially in increasing overall efficiency of operation.
In the '336 patent, the seat and backrest construction includes a plenum for receiving temperature conditioned air, which construction is formed alternatively from either metal wire spring coils or relatively rigid solid plastic tubes with sidewall openings formed therein. To function properly the seat construction must readily allow temperature conditioned air to pass throughout the entire plenum, not close off conditioned air flow to a significant extent from the weight of an individual sitting or leaning on the seating, and at the same time be comfortable.
Still further, automotive seat manufacturer's consider it undesirable that internal supports (e.g., spring coils) should produce a visible surface impression and in that way destroy design esthetics. For example, wire plenum coils and rigid plastic tubes end to “mark” the outermost seat covering (e.g., leather) which is undesirable. Also, it has been found in this regard to be self defeating to merely increase the thickness of a comfort layer located over wire springs or rigid plastic tubes since this reduces heat transference to the extent that overall operational efficiency is reduced.
A persistent problem with wire coils used to form a plenum in a seat such as a vehicle seat is that the coils spread the load weight too evenly giving the sensation of sitting “on top” of the seat rather than in the seat. Accordingly, an individual using the seat may often experience a lack of orthopedic support.
SUMMARY OF THE INVENTION
In describing the present invention in its various aspects, the term “cushion” will refer to a seat, a backrest or mattress-like item that has its temperature conditioned in accordance with and by use of the apparatus described. When either a “seat”, “backrest” or “mattress pad” is specifically referred to, those terms will be used.
It is accordingly a primary aim and object of this invention to provide a cushion for variable temperature use which includes an internal plenum for receiving selectively variable temperature air where the plenum is so formed as not to close off during use and yet is comfortable to the touch, does not give external signs of the plenum forming means, and does not require a relatively thick outer comfort layer covering which would create a prohibitive reduction in the level of heat transference.
As a first embodiment of a cushion, filaments of a strong and flexible synthetic resin material are used to form a plurality of loosely woven tubes held between a pair of similarly woven sheaths made from the same material. In this manner, a flexible porous and air permeable pad is provided which will be sufficiently rigid to resist closing off more than about 10% of any of the tubular chambers by someone normally leaning, sitting or lying on them and, in that way, enable conditioned air to pass along the tubular portions and outwardly through the woven walls to condition the full volume of the so-formed plenum within the cushion. Although the tubes are constructed of woven plastic filaments, the filaments are not secured to one another at crossover points, but the filaments are free to slide across one another at these points which results in more comfort to a user.
The cushion pad provided has air impermeable bottom and lateral sides while a loose woven textile top cover provides air permeability. For additional flexibility and comfort, a layer of foam of low to medium density and of open cell variety is inserted between the textile covering and the cushion plenum structure described in the immediately preceding paragraphs. The foam layer must be so constructed as to provide good air and vapor permeability.
A conditioned air inlet duct is affixed to the cushion rear edge and is formed to transmit the air into and along a predetermined number of separate channels into the cushion. Where a pair of cushions (e.g., seat and backrest) are to be provided with conditioned air, the duct provides separate multi-channel air streams to each cushion.
A cushion constructed of the referenced air permeable woven monofilament tubes can be sized to serve as a mattress or pad to be placed over a conventional mattress of similar dimensions or to serve as a mattress per se.
A heat pump preferably including a Stirling cycle conditioner is utilized for selectively reducing the temperature of pressurized air moved along a flexible hose to the cushion inlet duct. In practice, a Stirling cycle conditioner can be shown to be 5-6 times more efficient than a thermoelectric cooling device, and less expensive to manufacture. Also, for a given amount of heat pumped, a Stirling pump is smaller than a corresponding thermoelectric unit and approximately the same in weight per unit heat pumped.
The Stirling heat pump preferably is a sealed free-piston unit including a pair of helical coil springs coaxial with a balancing mass for reducing undesirable vibration. In cooling mode, the heat pump cools an outer surface portion (“cold” spot) over which a cap is secured with a set of radially extending heat exchanging fins and a further set of pin-fins. A conduit with a bonnet fitted over the heat exchanging fins and pin fins includes an internal fan for transferring the conditi
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