GB2362803A - Temperature regulated garment - Google Patents

Abstract

A temperature regulated garment includes one or more heating elements and/or one or more cooling elements located to cool directly only a part of a wearer's torso. Two or more heating elements are located at a front of the garment and a heating element located at the rear of the garment. A cooling element is provided in a collar of the garment. The garment is preferably in two parts, with the heating/cooling elements and battery in an inner part and a control input on an outer part.

Description

2362803 1 TEMPERATURE REGULATED GARMENT The present invention relates to a

temperature regulated garment.

Clothing with temperature regulation is known. Simple versions may have parts which can, for example, be sealed for warmth or opened or removed for cooling. More complex versions are provided with heaters and coolers, such as tubing through which warm or cold fluid can be passed.

There has not previously been provided, to the applicant's knowledge, temperature regulated clothing which can provide effective temperature regulation in a good range of ambient temperatures and which is suitable for everyday use.

The present invention seeks to provide improved temperature regulated clothing.

According to an aspect of the present invention, there is provided a garment including one or more heating elements and/or one or more cooling elements located to cool directly only a part of a wearer's torso.

The locations are such as to cause the wearer's body to heat of cool itself in response to activation of the heating or cooling elements.

In the preferred embodiment, there are provided heating elements located at a front of the garment and a heating element located at the rear of the garment, in practice over a wearer's spine.

Advantageously, there is provided a cooling element in a collar of the garment. It has been found that cooling a person's neck causes body cooling of the remainder of the person.

In the preferred embodiment, the heating elements are formed from a fibre mat of resistive fibres, for example the fabric Gorix(TM).

2 The cooling element is preferably a thermoelectric cooler, for example a Peltier element. The cooling element may include a heat-sink or a fan for directing heat away from the cooling element.

The garment is preferably provided with a user operable control unit for controlling the temperature of the jacket. In addition or in the alternative, the jacket may be provided with a thermostatic control.

In an embodiment, the garment is provided with a hood incorporating a cooling element, 10 preferably a cooling layer.

An embodiment of the present invention is described below, by way of illustration only.

The embodiment described is in the form of a two-part jacket. The first or inner part is provided with the control system, the power supply and the heating and cooling elements. The outer part is detachable from the inner part and includes a control input which can be coupled to the control system of the inner jacket and, preferably, a display for indicating the mode of operation of the jacket and the set temperature. The outer jacket also includes a hood, which may be cooled.

The purpose of the two-part jacket is that the expensive components are not fixed to the outer jacket, which is the part giving the appearance of the item. Therefore, several different outer jackets could be provided.

Thermoelectric Cooling Collar and Cooling Hood Although there are several areas of cardio-vascular arteries throughout the human body, the neck area is the most important in terms of cooling the body easily and quickly. This area contains a major vascular network at the back of the neck, and a set of arteries called the carotid arteries. If these arteries are cooled it is possible to cool the blood 30 which flows to the brain.

3 Studies have shown that if this area is cooled then the wearer will experience the feeling of whole body cooling, as well as reduced stress and even a reduced heart rate. This is why a trainer in boxing will always apply an ice pack to the back of the boxer's neck between rounds to revitalise and refresh him.

The feeling of 'whole body cooling' occurs because as the blood flows up the back of the neck to the brain it first passes over the hypothalamus, one of the body's two temperature sensors (the other being the skin). Since the blood flowing across the hypothalamus has been cooled, the brain is 'fooled' into thinking that the whole body is cooler than 10 actually is.

it It was thought that there might be a way to capitalise on this fact by designing a 'cooling collar' which would fit tightly against the neck of the wearer. The collar would cool just this area but would give the effect of whole-body cooling. This would have the advantages of being light and inexpensive, but would not require the energy consumption of a whole-body solution. If a thermoelectric system were employed, the collar could be turned on and off and adjusted as required.

Besides the neck, cooling the head and any area overlying active muscles can also provide excellent heat removal per unit of skin surface area. Other areas include the armpits and the groin. When a patient is suffering from heat stroke, doctors are always advised to apply ice packs to these areas to lower core body temperature.

It was decided that a cooling hood and a thermoelectric cooling collar should be developed to be used as the cooling media within the garment.

Product Architecture On the basis of the chosen heating and cooling media, it was decided for this embodiment to form the garment as a tight fitting waistcoat or vest 'liner' which could be zipped into a number of 'system-specific' over-garments such as a sweatshirt, windproof jacket, waterproof or fleece.

4 The advantages of this arrangement are as follows:

1) the textile heating pads and the cooling collar must be kept close to the body in order for them to be efficient, therefore it follows that they should be held within some tight fitting liner. Similarly the battery, which constitutes the bulk of the weight in the garment, should be held close to the body such that its weight becomes less obvious; 2) as a result of the expense of the hardware within the garment, if the liner can be used with a number of different over garment designs, rather than being permanently stitched into one garment, this increases the value of the system; 3) by making the over garments 'system specific', the manufacturers can capitalise on the design by ensuring that the customer cannot use the liner without one of their garments over the top of it. This could be achieved by including a necessary part of the circuit within the over garment itself.

Position and Size of the Electro-conductive pads Tests have established that there are three areas of the torso which, when heated, can provide warmth across an area greater than their own. These are the main blood flow areas which overly the major organs; the two kidneys (in the lower back) and the chest. For example, if the area overlying the kidneys is heated, the warmed blood from this area will circulate upwards through the body to warm the shoulders. Similarly, applying heat to the chest will heat the upper arms. It follows that if textile heating pads can be applied to these three areas then a greater proportion of the body can be warmed than is paid for in terms of applied energy.

The garment uses three textile heating pads: one covering the kidneys and lower back, and one covering each half of the chest to allow for a zip or opening down the middle.

The maximum feasible pad size was calculated based on the current drawn per square of the fabric at the maximum desired output temperature, based on a 12 volt input:

(Resistance of textile in current flow direction x ((width/length)) + (length of bus bar x 2) Resistance of fabric and attachments.

A 30 em x 30 em (12" x 12") square pad producing 41T at 12 volts will draw 2.9 amps. This is a large enough pad to cover both of the kidneys and lower back up to the shoulder blades.

Two 15 em x 30 em (6" x 12") rectangular pads would be large enough to cover the two sides of the chest. A single 15 em x 30 em (6" x 12") pad producing 41'C at 12 volts will draw 0.8 amps. This means that the entire three pad system of the preferred embodiment will draw 4.5 amps to provide 41T.

These estimates assume that the copper bus bars which deliver the current to the pads are attached to the short sides of the pads. With the bars in this position the system will draw less current because the bars are shorter. However, the time to heat up will be longer because there is a greater distance for the current to flow between the two bars. Where battery size (and thus current consumption) is important the bars should be placed along the short side of these pads.

The bus bars should also be aligned parallel to one direction of the fabric; either the warp or the weft. In Gorix(TM) fabric, the current always travels perpendicular to the bus bar, so if the bus bar is aligned with the weft, the current will be forced to travel in the warp. This is of benefit, as the warp is woven such that it has greater resistance than the weft (4 ohms per square across the warp against 3 ohms per square across the weft for Gorix with Nylon Tricot laminate). Thus, the electrical resistance of the pad will be increased as will the temperature which can be achieved at a given voltage.

Determining the Stabilising Laminate and Insulating Layers A square woven Nylon Tricot laminate was chosen to be bonded to both sides of the heaters. Nylon Tricot laminate is light (220 Gm/m2), has excellent breathability, good abrasion resistance and is relatively flexible and resistant to tearing.

6 Since Gorix heating elements are very energy inefficient, it is important to conserve what ever heat is produced by the pads and not to let it escape to the atmosphere before it can be used. To prevent such heat losses the vest liner preferably includes an insulating layer over the top of the Gorix pads. A quilted insulator is ideal for this application, preferably one in which the fabric is constructed from two layers, a woven Nylon outer and a very fine insulating batting. The Nylon forms a supportive 'backbone' for the laminate, while the batting creates a dead space which traps the hot air to prevent it from escaping. The open (inside) face of the batting is also dusted with an aluminate layer which is applied by vapour deposition. The vapour sets to form droplets of aluminium on the face of the fabric which act as secondary insulators and also as reflectors.

As the aluminate layer covering the batting is electrically conductive, it was necessary to introduce an electrically insulating sleeve between the batting and the Gorix pads. This is to prevent the pad from short circuiting across the aluminium droplets. A Nylon sleeve was specified as the insulator, as the fabric is light, thin, flexible and resistant to wear and is inexpensive and readily available.

Development of Cooling Media Thermoelectric Cooling Colla The cooling collar was developed with the intention of cooling the vascular network at the back of the neck. A Peltier TE module with a small heat-sink and fan is preferably provided for the hot side and a curved aluminium cold plate for the cold side to transfer the cooling effect to the back of the wearer's neck.

The characteristics and performance of the cooling collar are preferably as follows: a) for discretion, the cooling fan must be no louder than 25 dB @ 30 cm; b) the unit must be of such size, shape and weight that it does not cause discomfort either through its own weight or through deformation of the garment to which it is attached; c) the unit must have a size and shape which do not compromise the style and appearance of the garment; 7 d) the temperature achievable at the cold plate is preferably equal WC at full power; e) the exposed face of the fan should be appropriately guarded to prevent finger trapping or contamination of the airway.

In the preferred embodiment, the heat-sink used on the hot side of the Peltier device in the cooling collar is an IMI Marston CP464 series Peltier cooler. These heat-sinks are designed specifically to manage the high power output generated by thermoelectric devices. They have a tightly packed array of very thin section fins which has more surface area to dissipate heat than a conventional machined or cast finned heat sink.

A primary concern with the cooling collar was that the weight of the heatsink and fan on the back of the neck may pull the collar of the vest liner backwards and downwards, choking the wearer at the throat. In order to reduce the chances of this occurring, the heat-sink and fan should be kept as small and/or as light as possible to keep weight to a minimum.

In tests, 45 mm' and 60 mm heat-sinks were both able remove enough heat from the hot side of the Peltier device to allow the cold side to drop below 10'C. However, in the case of the 45 mm' heat-sink, it took 15 seconds longer for the temperature of the cold side to drop below 10'C relative to the 60 mm heat sink. Despite this, the 45 mm2heat sink and fan might be preferred over the 60 m' combination when the advantages of reduced size and weight outweigh the disadvantages of the slightly slower drop in temperature.

Evaporative Cooling Hood Cooling the head can provide excellent heat removal per skin surface area, and also has the added benefit of greatly enhancing thermal comfort. The preferred cooling hood can provide a cool, dark, consuming cocoon for the wearer to 'retreat into' away from the stress and heat of a busy urban environment. Psychological benefits equivalent to the cooling hood can be felt by closing one's eyes in a hot or stressful environment; where 8 shutting out the outside world appears to calm the mind and reduce heat stress, thereby cooling the body down.

In the case of the cooling hood it is preferred to have a passive cooling fabric for the hood lining. The fabric lining can be activated at the start of each period of use and the cooling hood then be donned and doffed by the wearer as and when cooling is required.

An evaporative cooling fabric is preferred for the hood lining. This is primarily because these fabrics are light and inexpensive but also because they offer uniformity of cooling across the entire surface of the material and long duration cooling.

The preferred cooling fabric is Aquatex Industries' Hydroweave(TM) fabric. Hydroweave is a performance enhancing fabric which works by using a foamlike core which consists of water retaining polymer strands woven into an absorbent batting. The batting is a blend of hydrophilic and hydrophobic fibres. This combination readily absorbs water and distributes it evenly across the entire area of the fabric such that a uniform evaporation occurs whenever warm, dry air passes across it. The fibrous batting is quilted between a breathable exterior shell and a laminated microporous lining. The lining is a thermally-conductive membrane which carries cooling to the body, while allowing perspiration escape, keeping the wearer cool and dry.

To activate the Hydroweave fabric, it is soaked in water for 5 minutes to saturate the water absorbent fibres. Once activated, excess water is wrung out and the garment wiped dry. Water locked-in to the absorbent fibres is suspended within the batting to provide up to eight hours of cooling comfort. The fabric provides quick activation time and extended period of evaporation over conventional cooling fabrics. Hydroweave also has the following advantages:

a) it evenly distributes cooling effect over the entire fabric, unlike loose granular polymers, ice-packs, phase change or capillary products; b) it has a pliable construction; c) it is rugged and machine washable; 9 d) it is reusable; e) it can cool without the weight of excess water; f) it can cools 'dry' without the feel of moisture or gelatine; g) it is easily reactivated; is Support Components Battery Battery selection for the preferred embodiment is based on the following criteria:

1) the Peltier device and the Gorix heating pads both draw considerable current (1.6 amps and 4.2 amps at 12 volts respectively) and so an important variable in battery selection is battery life or capacity. The product should be capable of operating for one hour at full power in either heating or cooling modes before a recharge becomes necessary. This suggests a battery with a capacity of at least 4.2 Ali (4.2 amps x 1 hour); 2) the battery should also have a maximum discharge current of at least 4. 2 amps. That is the maximum current capable of being drawn continuously from the battery over its entire discharge time; 3) as the battery would need to be carried within the garment, size and weight are also of importance.

A cell or cells with Nickel Metal Hydride chemistry would best suit the described embodiment.. This is primarily because NiMH cells have a greatly enhanced capacity over Nickel Cadmium cells but also because these cells have a unique characteristic in that they have no 'memory'. That is, they will not lose any capacity if they are not fully run down before each charge. The cells also have an environmental benefit in that they do not contain lead.

The selected cell size for the preferred embodiment was the 7/5 AF; a 1.2 volt NiMH battery with an unrivalled capacity of 3.8 Ah and a maximum discharge current of 10 Amps. A 12 volt battery pack was made up using two rows of five of these cells and then a shrink sleeve was applied to insulate the live terminals and protect the battery pack from damage. Due to the high current being drawn, the battery pack should include a short circuit protection device. This would prevent the battery from overheating in the event of a short circuit. A Borne polyswitch protection device is preferably soldered in place of one of the solder tags on the batteries.

In a prototype, the completed battery pack measured only 85 x 67 x 35 mm, a size which would make it feasible to slip the pack into a tight fitting pocket on the vest liner.

Of course, the selection of the battery should be determined on the basis of battery technology current at the time of putting this invention into practice.

Temperature Control Circui The temperature control circuit allows the wearer to switch between heating and cooling modes and to adjust the temperature of the active element (either the Peltier cooling device or the Gorix heat pads).

A very simple embodiment could use only a rotary potentiometer in parallel with the active element to form a potential divider. By turning a dial connected to the control potentiometer, the user would apply more or less voltage to the active element, adjusting its temperature. This system is sound in principal, but the problem is that it takes no account of warm-up time. For instance if the user only wants to be warmed up slightly, turning the potentiometer a small amount to achieve this will take a relatively long time to achieve even a slight rise in temperature.

Alternatively, if the circuit is designed such that the total available voltage is automatically placed across the active element on start up, then as long as the system checks the potentiometer for the required end temperature, the warm-up time can be shortened greatly. The preferred circuit provides this facility. Temperatures read from the control potentiometer are converted to a binary value using an on-board A-to-D converter. These are then repeatedly checked against a second binary value from a counter approximating the resistance of a thermistor on the active element. When the 11 two binary values become equal the element is deemed to have reached the desired temperature and the voltage across the element is switched repeatedly to maintain that temperature. The specific details of the circuit will be readily apparent to the skilled person.

As the input from the control potentiometer is converted into a binary value between 0 and 255 (in this example), the accuracy of the control circuit could be described as being the temp, range/255 = 0. 137 1 C or + /-0. 068 0 C. Considering that the Gorix heat pads and Peltier device only have a temperature stability of +/-0.21C, the control system 10 could be said to be sufficiently accurate.

A further benefit of this design of temperature control circuit is that once the active element reaches the desired temperature and the supply voltage begins to pulse on and off, the current is only drawn intermittently. This preserves battery life and increases the 15 maximum allowable current draw from the battery.

LCD Display The LCD display provided on the left cuff of the over-garment can give visual feedback of adjustments made to the temperature control dial. If the display shows the requested temperature in degrees Centigrade, for example, users could potentially remember "favourite temperatures" for different environments or weather conditions. The active element could then be set to these temperatures quickly, with no further adjustments being required. The display can also indicate the current mode of operation, that is heating or cooling.

Further Features In the preferred embodiment, the material used for the heating elements has a resistivity which changes substantially linearly with variations in temperature. In t is case, the heating pads can effectively be configured to measure their own temperature to provide a 30 self-regulating system, as will be apparent to the skilled person.

12 The control circuits are preferably provided with over/under temperature safety cutout switches to prevent over and under heating in the event of a malfunction such as a short circuit. The set temperature is preferably fed back via the micro-controller to a small LCD screen provided on the jacket for example on a sleeve.

It is envisaged that the neck piece can be designed to provide for both cooling of the neck area and for heating thereof. With the use of a Peltier element, cooling and heating can readily be achieved by reversing the current through the Peltier element.

It is possible to design the heating and cooling elements to have more (or exclusively) Peltier elements or similar thermoelectric heaters/coolers, such that both heating and cooling can be provided over a large area of a wearer's body. This can have significant applications in the medical environment where it may be important to keep a patient at a known constant temperature. In such a case, the article need not be only a jacket but could be any item of apparel or cover such as a blanket.

As Peltier elements draw a lot of current, if many are going to be used, it would be preferable to couple these to a heat dissipator to maximise their effect.

13

Claims (1)

1. A garment including one or more heating elements and/or one or more cooling elements located to cool directly only a part of a wearer's torso.

5. A garment according to any preceding claim, wherein the cooling element or elements include a thermoelectric cooler, a heat-sink or fan.

2. A garment according to claim 1, wherein there are provided heating elements located at a front of the garment and a heating element located at the rear of the garment.

3. A garment according to claim 1 or 2, wherein there is provided a cooling element in a collar of the garment.

4. A garment according to any preceding claim, wherein the heating element or elements are formed from a fibre mat of resistive fibres.

6. A garment according to any preceding claim, including a user operable control unit for controlling temperature.

7. A garment according to any preceding claim, including a hood incorporating a cooling element.

8. A garment according to any preceding claim, wherein the garment is formed in 25 two parts.

9. A garment substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.