WO1991016022A1

WO1991016022A1 - Cooling device

Info

Publication number: WO1991016022A1
Application number: PCT/AU1991/000125
Authority: WO
Inventors: Allan Peter Ryan
Original assignee: Koolit Intellectual Properties Pty. Limited
Priority date: 1990-04-12
Filing date: 1991-04-04
Publication date: 1991-10-31
Also published as: ZA912661B

Abstract

A cooling device (1) for removing heat from a body comprising a core (2) extending from one end (3) to an opposite end (4) and having a square cross-section defined by sides (5, 6, 7, 8). Core (2) is capable of absorbing and holding a quantity of liquid and further adapted to release the liquid slowly through evaporation for removing heat from the body. The sides (5, 6, 7, 8) are approximately 2 centimeters in dimension and the core length is approximately 35 centimeters. Core (2) is sleeved by a tubular textile covering (9) which is seamed by stitching in the axial direction and at respective covering end portions (10, 11).

Description

Title: "COOLING DEVICE"

Technical Field

This invention relates to a cooling and dehydration prevention device.

Background Art

Humans regulate body temperature by secreting moisture in the form of perspiration or sweat when either the ambient temperature exceeds body temperature or when, by exertion, the body temperature increases above normal body temperature. The latent heat of evaporation of moisture from the skin reduces the body temperature.

The greater the difference between normal body temperature and a higher ambient temperature, or the greater the body heat generated by exertion, the greater the rate of perspiration. The quantity of body fluid lost under such conditions may be considerable and may cause dehydration, the effects of which may be severe, or even fatal .

It has been practiced to cool the body by fanning, to increase the rate of evaporation of sweat while periodically imbibing fluids to maintain a fluid balance.

It has also been practiced to cool the body by sponging with water or by application of a "cold

compress" which is a sponge containing chilled water. Those methods result in the body being coated with a film of water. It has also been practiced to cool the body by tying a wet handkerchief or bandanna about the forehead. This suffers from the disadvantage that the bandanna when wet, drips or else if only moist, soon dries out and becomes ineffective. In this case, the quantity of water lost by evaporation is typically so low that no cooling effect is noticeable.

Disclosure of the Invention

An object of this invention is the provision of simple and effective means for cooling the body and which avoid or at least ameliorate the disadvantages of prior art. Another object is to provide apparatus and a method for reducing loss of body fluids in consequence of elevated ambient temperature and/or resulting from exertion.

According to one aspect, the invention provides a cooling device for removing body heat comprising a core material capable of absorbing and holding a quantity of liquid, and means for retaining the device in thermal communication with a body, the. core material being adapted to release the liquid slowly through

evaporation, whereby in use said evaporation extracts heat from the body.

A device according to the invention can, for example, be worn encircling the neck which carries a relatively large volume of blood circulating in

proximity to the skin. The device is secured in place so as to be in effective, but comfortable, thermal communication with the adjacent skin surface. The core material has a sponge-like structure and prior to use, is engorged with water. As the water evaporates, latent heat is extracted from the device and in turn from the adjacent body.

In preferred embodiments of the invention, the core material is pliant when moist and thus conforms

comfortably to the body of the wearer. Moreover, the core material desirably is selected to have a

labyrinthal and continuous pore structure and preferably is selected as having an average pore size of less than 100 microns.

It is highly preferred to select as the core a sponge of the type made from water soluble polyvinyl alcohol ("PVA") acetalized with an acid catalyst.

It has been found that the preferred selected materials not only hold a suitable quantity of water, but bind it within the core structure so that water tends not to drip onto the wearer, have sufficient stiffness when moist so as not to exude water during use, and expose a large surface area of water to the atmosphere to facilitate evaporative cooling.

It is also preferred to retain the core material in contact with the body by means which provide a water vapour permeable covering to the core material as well as facilitating attachment to or detachment from the body.

Brief Description of the Drawings

The invention will now be more particularly

described by way of example only with reference to the accompanying drawings wherein:

Figure 1 is a perspective view of a device

according to the invention placed on a wearer;

Figure 2 is a plan view of the device shown in Figure 1;

Figure 3 shows a cross-section through the device on line 3-3 of Figure 2.

Figure 4 is an expanded view of the retention system shown in a "retaining" configuration.

Modes for Carrying Out the Invention

With reference to the drawings which are not to scale or to the same scale, there is shown an embodiment of a device according to the invention.

The device 1 comprises an elongate core 2 extending from one end 3 to an opposite end 4 and having a square cross-section defined by sides.5, 6, 7, 8. In the embodiment described, the sides 5, 6, 7, 8 are each approximately 2 cms in dimension and the core length from end 3 to end 4 is approximately 35 cms.

Core 2 is sleeved by a tubular covering 9 of a textile - for example, cotton fabric which is seamed by stitching in the axial direction and at respective covering end portions 10, 11.

In the illustrated embodiment, end portions 10 and 11 are respectively provided with a strengthened tab 12 and a plurality of button holes 13 for receiving and releasably retaining tab 12. Alternatively a hook and loop attachment system (e.g. "Velcro" type) or press stud or other fasteners can be used.

Core 2 is a PVA sponge made from water soluble PVA acetalized with an acid catalyst and available from Kanebo Limited.

The selected material has a specification as shown in Table I.

Core material having a pore size of less than 150 microns is preferred and a pore size of less than 100 microns is more highly preferred. The preferred

material absorbs from 900 to 1500 weight % of water. The sponge is hard and stiff when dry, which facilitates manufacture and assembly of the device (especially insertion in the fabric cover) and is pliant when moist which facilitates comfortable accommodation of the device to the shape of each wearer.

That in turn improves thermally conductive

communication with the wearer's skin.

It is important that the core material holds a sufficient quantity of liquid to provide cooling over a usefully long duration.

The core material should be able to bind the liquid sufficiently to prevent the water from dripping in use and desirably is of sufficient stiffness that water is not easily squeezed from the core during activity by the wearer.

The core material and covering (if any) must in combination be capable of releasing the liquid through evaporation and desirably provides a substantial water-air interface to facilitate evaporation. The labyrinthal and continuous pore structure having an average pore size of less than 100 microns has been found to provide these properties while natural sea sponge and a very large number of other synthetic sponge materials failed in one or more respects to perform in the manner described, most tending either to drip down the neck of a wearer in use and to lose liquid so rapidly as to reduce the time effectiveness of the device below acceptable levels or else to provide an inadequate rate of evaporative cooling.

The preferred materials become progressively stiffer as evaporation proceeds enabling the wearer to gauge the quantity of liquid remaining in the core by the degree of stiffness of the device.

Desirably, the core material is of a non-allergic material.

The most highly preferred material for use as core 2 is Kanebo Limited 's "Grade D" PVA sponge which has a porosity of 88%; an average pore size of 60 micron; an apparent density of 0.094 g./cm.; a 30% compressive stress of 86 g./square centimeter; a tensile strength of 5.9 Kg./square centimeter; a tensile elongation of 250% and a water absorption rate of 1020 weight %, but similar materials may be used.

In use, the core of the device of Figure 1 is first engorged with water for example by soaking. The

covering 9 quickly dries to a damp state. The

water-laden core is pliant and the device can be worn, for example, encircling the neck. Tab 12 is pulled through a selected button hole 13 and adjusted for comfortable skin contact. This system of fastening facilitates adjustment of the circumferential dimension of the device and provides adequate retention.

Water evaporates from the core through covering fabric 9, the device being cooled as latent heat is extracted and feeling subjectively cool to a wearer at rest without feeling excessively wet. If worn while the body undergoes exertion, water is not squeezed from the core. The cooling effect continues for a period of surprising duration which depends upon factors such as ambient temperature, air movement relative the device and generation of body heat.

It is believed that when worn about the neck, the cooling effect of the device on the blood circulation of the wearer results in the body temperature control mechanism not needing to signal the body to sweat to compensate for heat increase and thus any tendency to dehydration is reduced.

For example, a test was conducted whereby 16 male and female subjects undertook an eight minute treadmill run. The speed of the treadmill was 10 km/hour for males and 8 km/hour for females, with a 5% grade being used in all cases. Two runs were completed by each subject, the device being worn only in one test.

The runs were separated by a week and the order was randomised. The temperature and humidity conditions of the laboratory were maintained at 20 to 24°C and 50 to 65% humidity respectively. Furthermore, a fan was placed in front of the treadmill to allow air to pass the subject under test.

Prior to the run, the mean oral temperature of the subjects was found to be 36.3°C. Upon completion of the run when not wearing the device this value had increased to 36.7°C. In contrast, when the device was worn, the mean oral temperature was found to be 36.4°C, that is, not significantly different from the starting level. Furthermore, upon measuring the heart rates of the subjects, it was found that the average when the device was worn was 156 heart beats per minute. However, without the device this average was found to be 160 heart beats per minute. This reduced heart rate is reflected by a reduction in the average weight loss through dehydration.

A further example of the cooling properties of the device was provided by a test carried out on eight male subjects running for thirty minutes on a motorised treadmill at approximately 70% of their maximum heart rate reserve. In all cases the treadmill speed was held constant at 10 km/hour and the grade altered until the heart rate was approximately 5 heart beats per minute below the target rate.

Two runs were undertaken by each subject, separated by four days. The laboratory conditions were maintained as for the eight minute run.

The oral temperatures of the subjects were measured ten minutes after the completion of the exercise. When wearing the device it was found that the average

increase in oral temperature was 0.34°C, compared with 0.53°C when the device was not worn.

The average heart rates of the subjects were obtained at five minute intervals throughout the

exercise and it was found that at all the sample points the average heart rate was less when the device was being worn. A measure of weight loss following the exercise revealed that the average weight loss was also less when the device was worn. The difference between the average weight loss "with" and "without" the device was larger than for the eight minute run, suggesting that the device appears to be effective over a long time for reducing the need for the body to utilise

evaporation to dissipate heat.

During both of the abovementioned tests an

assessment of the rate of perceived exertion (RPE) was undertaken. The difference between the RPE's for the "with" and "without" conditions were analysed using a single tailed t-test, with a 0.05 level of significance.

The eight minute test gave an RPE for the condition when wearing the device at 11(±2) and when not wearing the device 12 (±2). The corresponding values for the thirty minute tests were 13.30 and 14.04 respectively. These results suggest that when wearing the device the subject was less stressed, for both short and longer periods of exertion.

As will be apparent to those skilled in the art from the teaching hereof, the device may be embodied in other forms and dimensions.

For example, the core may be of rectangular, circular or other cross-section, a plurality of core shapes may be provided and these may but need not be connected together, or the device may be adapted for attachment to other parts or limbs of the user.

The dimensions and shape are preferably selected to provide a sufficient area of contact with the skin and also to provide a satisfactory area open to the

atmosphere for evaporation.

The device may be adapted for attachment to the body by means other than those illustrated, for example elastic or elongate ties at the free ends of the cover or by press studs or other fasteners. The cover is desirably of a decorative appearance and may be made from other water vapour permeable fabrics. It will be understood that in less preferred embodiments, the core may be secured directly to the wearer without use of cover 9.

The device may be stored and/or merchandised in a wet charged condition in a water impermeable package or container and in that state the device may be coiled into a spiral form. In that case, a fungicide may be included.

Claims

CLAIMS : -

1. A cooling device for removing body heat comprising a core material capable of absorbing and holding a quantity of liquid, and means for retaining the device in thermal communication with a body, the core material being adapted to release the liquid slowly through evaporation, whereby in use said evaporation extracts heat from said body.

2. A cooling device according to claim 1 wherein the retaining means includes a water vapour permeable covering for the core material.

3. A cooling device according to claim 1 or claim 2 wherein the retaining means includes means for

facilitating attachment to the body.

4. A cooling device according to any one of the preceding claims wherein the core material is pliant when moist for conforming to the body.

5. A cooling device according to any one of the preceding claims wherein the core material has a labyrinthal and continuous pore structure.

6. A cooling device according to any one of the preceding claims wherein the core material has pores of an average size less than 150 microns.

7. A cooling device according to any one of the preceding claims wherein the core material has pores of an average size less than 100 microns.

8. A cooling device according to any one of the preceding claims wherein the core material is an

elongate synthetic sponge.

9. A cooling device according to claim 8 wherein said sponge is made from water soluble polyvinyl alcohol acetalized with an acid catalyst.

10. A cooling device according to any one of the preceding claims adapted to be worn around the neck of said body.

11. A cooling device according to any one of the preceding claims wherein the retaining means includes a zone of hooks, of the kind used in hook and loop

fastenings, and a corresponding region of loops located at the opposite end of said retaining means.

12. A cooling device according to any one of the preceding claims wherein the retaining means includes a first elongate tab extending at or adjacent one end of said covering, and a second tab extending at or adjacent the other end of the covering, the first tab including a strengthened portion and the second tab having at least one hole for retaining said strengthened portion.

13. A cooling device according to any one of the preceding claims having a flat side adapted to be adjacent the body.

14. A cooling device substantially as herein described with reference to the accompanying drawings.

15. A method for removing heat from a body using a cooling device as defined in any one of the preceding claims, said method comprising the steps of:

engorging said core material with liquid;

retaining device in thermal communication with the body; and,

allowing the liquid to evaporate whereby to extract heat from the body.