GB2382017A

GB2382017A - Air channel arrangement in ventilated footwear

Info

Publication number: GB2382017A
Application number: GB0127466A
Authority: GB
Inventors: Chris Towns; Paul Armstrong
Original assignee: Clark C & J Int Ltd; C&J Clark International Ltd
Current assignee: Clark C & J Int Ltd; C&J Clark International Ltd
Priority date: 2001-11-16
Filing date: 2001-11-16
Publication date: 2003-05-21
Also published as: AU2002343025A1; WO2003043454A2; WO2003043454A3; GB0127466D0; AU2002343025A8

Abstract

In the undersurface of an under-foot, insole, layer in a shoe a pump in the heel portion 12 draws air in through one or more passages 19 and pumps the air through a plurality of passages 16 to holes 17 at the toe end of the shoe, supplying air to the foot compartment. More air may be supplied to passages 16 through passage 24b, entrained by the outflow from the pump. The channels may include reversible one-way valves (Figs 8a to 8d), formed as reversibly domed, slitted, membranes. The pump (Figs 9 and 11) comprises a pumping chamber having a flexible bellows and inlet and outlet one-way flap valves. The pump supplies a plenum chamber 21 having an outlet valve to the passages 16 requiring an opening pressure greater than that produced by one stroke of the pump to increase the flow to the passages 16.

Description

IMPROVEMENTS IN FOOTWEAR This invention concerns improvements in footwear.

In the field of footwear it is known to make use of volumes of air or other gases typically in compartments formed in the midsole or footbed portions of eg. a shoe, for various purposes.

For example it is known to provide in the midsole of a running shoe or a training shoe one or more chambers that are filled with air that is in some cases pressurised. The primary purpose of such chambers is to provide shock absorption in shoes that typically suffer repeated impacts in use.

It is also known to incorporate within a footwear item apparatus for circulating air within a chamber that is in use occupied by the foot of a wearer.

In particular it is desirable to provide an arrangement for aerating with comparatively fresh air the region of a footwear item that in use surrounds a wearer's toes. Such an arrangement enhances the comfort of the footwear item, reduces moisture in the vicinity of the wearer's toes and reduces the incidence of bacterial growth.

Patent number US 5,282, 324 discloses a shoe having a foot-actuated, positive displacement pump located in the heel of the midsole thereof.

The inlet of the pump is connected to draw fresh air from the atmosphere via a vent. The outlet of the pump is connected to pump fresh air into a flow channel interconnecting the heel and toe portions of the midsole.

The pumped air passes via a series of throttling orifices into an air flow

channel, that is connected to atmosphere at a location remote from the toe end of the midsole.

The passing of air via throttling orifices into the air flow channel causes the pumped air to accelerate dramatically. According to US 5,282, 324, such acceleration causes jet entrainment of a large volume of fresh air that enters the flow channel via the vent. The entrainment action is such as to propel the large volume of fresh air towards the toe end of the midsole, where it exits the flow channel via a series of apertures passing through the toe portion of the midsole, to aerate the toes of a wearer of the shoe.

By the planting of the heel of the shoe a wearer with every step compresses the pump to cause the above-described action. A restoring spring causes the pump to expand on the lifting of the heel between each step, so that the pump is re-charged ready for the next subsequent step.

Although the arrangement of US 5,282, 324 apparently is capable of forcing a large volume of air past the wearer's toes in use, it suffers from several disadvantages.

The first of these relates to the flexibility of the materials of many sports and leisure shoes, and to the variability in the gaits of wearers thereof.

Depending on the precise circumstances of use of a shoe as shown in US 5,282, 324, and on the gait of the wearer, it is possible for the air flow to cease by virtue of the wearer's weight deforming the air flow channel sufficiently to block the flow of air therethrough. This problem rarely manifests itself in the case of a wearer whose gait is normal. However significant proportions of the population are so-called"pronators"and "supinators", whose gaits are much more likely to block the air flow channel.

Such deformation of the air flow channel constricts the air flow channel to a greater or lesser amount. If blocking of the channel occurs as the wearer plants his foot with every step, the aeration of the toes would substantially cease because the air flow channel would be blocked each time the pump ejects air into the air flow channel.

In addition the shoe of US 5,282, 324 conveys air around the toes at a considerably lower velocity than that at which the entraining air emits from the pump. Many wearers of a shoe such as that shown in US 5,282, 324 may find the sensation of aeration to be largely imperceptible as a result of the comparatively low velocity at which the air passes around the toes.

Patent number US 6,041, 519 discloses another shoe in which the heel of the midsole portion incorporates a series of voids defining a suction pump.

The suction pump is connected via a plurality of air flow channels to the ball/toe region of the midsole, from where it draws stale air via perforations passing through the midsole in the in-use vicinity of the wearer's toes.

The suction pump in US 6, 041, 519 works, like the pump in US 5,282, 324, by entraining a volume of air in an air flow channel. Nonetheless the arrangement of US 6, 014, 519 is also believed not to provide a readily perceptible feeling to a user of aeration of the toes and/or the ball of the foot.

In view of the foregoing defects in the prior art arrangements, there is a need to improve the aeration of the ball/toe regions of footwear items such as shoes (including but not limited to leisure shoes, walking shoes and sports shoes such as running shoes and training shoes), boots (including but not limited to wellington boots, walking/hiking boots and various boots

designed for use in particular sports) and other items of footwear.

According to a first aspect of the invention there is provided an under-foot layer comprising a ball/toe portion and a heel portion that are interconnected by an arch portion, the layer in use in a footwear item lying beneath a foot chamber defined by one or more uppers, a face of the layer that is in use remote from the said foot chamber having formed therein a plurality of air flow channels extending between the ball/toe portion and a portion of the layer remote therefrom for conveying air between the said portions, at least one said channel communicating with one or more further channels that perforate the layer in the ball/toe region and at least one said channel in use of the layer being connectable to a pump for causing conveyance of air to the ball/toe portion from the said portion of the layer remote therefrom via a branched flow path defined in the said plurality of channels.

An advantage of providing a branched flow path whose function is to permit conveyance of air to the ball/toe portion of the under-foot layer from a portion of the layer remote therefrom is that the likelihood of blocking of the air flow channels is significantly reduced.

In the case of an air flow path that is branched only once, in order to provide a pair of air flow path branches, it is believed that the likelihood of the gait of a wearer of a footwear item incorporating the under-foot layer completely blocking both branches is virtually zero.

Preferably the under-foot layer includes formed therein a first air chamber that is spaced from the said ball/toe region and that is in fluid communication with the said plurality of air flow channels, the first air chamber being connectable to the outlet side of a pump for conveying air.

This arrangement allows the under-foot layer of the invention to be readily connected to a pump that is incorporated within a footwear item.

Conveniently the under-foot layer includes formed therein at least one supply channel for supplying air to such a pump. In preferred embodiments the under-foot layer includes a plurality of the supply channels formed in the said face of the layer that is in use remote from the said foot chamber of the footwear item in which the under-foot layer is used.

These arrangements advantageously permit the supply of replenishing air to a pump in the footwear item.

More specifically, each said supply channel interconnects a periphery of the layer and a further air chamber that is connectable to the inlet side of a pump for conveying air.

This arrangement allows the drawing of fresh air for pumping towards the ball/toe portion, eg. via the side of the midsole portion of a shoe. The midsole portion may be made gas permeable by any of a number of known means in such a region.

Preferably when the under-foot layer includes the first air chamber as aforesaid, the plurality of air flow channels may include a primary air flow channel that is in communication with the first air chamber and that extends therefrom towards the ball/toe region, the primary air flow channel being bifurcated at a region remote from the ball/toe region to define at least two air flow branches.

The precise point of bifurcation of the air flow channel may be chosen advantageously to minimise the risk of blocking of both the branches thereof in use of the under-foot layer.

More specifically, the bifurcation preferably lies in the heel or arch portion of the under-foot layer. Forward of this point the pressure exerted by the wearer becomes highly unpredictable. Having a plurality of air channels forward of the arch region, therefore, reduces the risk that all of the air channels could be blocked during normal use. Having fewer air channels rearward of the arch region carries an acceptable risk.

This is because the bones of the foot are substantially fused in the heel region. Pressure is, therefore, applied in the heel portion in a largely predictable and repeatable way. The bones of the arch (or midfoot) on the other hand are not fused, but only one of these bones bears regularly upon the footed. This is the'cuboid'bone, running from the'outside'of the heel towards the little toe. It is desirable, therefore, that at least one channel in the arch region and portions of the layer lying forward thereof avoid the area supporting this bone.

In alternative arrangements within the scope of the invention the air flow channel may be branched more than once.

In a particularly preferred embodiment the two air flow branches are interconnected to define an air flow loop, whereby air being conveyed to the ball/toe portion may travel via either or both branches of the air flow channel in order to reach its destination.

In one preferred embodiment of the invention the under-foot layer may include at least one secondary air flow channel interconnecting a periphery of the under-foot layer and part of the primary air flow channel. This arrangement allows for the advantageous augmentation of air pumped by a pump to which the under-foot layer is connected, by fresh air ingested eg. via a permeable portion of the side of the midsole portion of a shoe.

Since the under-foot layer of the invention omits the throttling orifices of US 5,282, 324, the method of ingestion of fresh air is not that of jet entrainment as disclosed US 5,282, 324. On the contrary, the method is that of a Bernoulli effect, whereby the pumping of gas into the primary air flow channel causes a pressure drop therein that sucks air via the secondary air flow channel from the exterior of the under-foot layer.

The ratio of the volume of air ingested in this way to the volume of air pumped by the pump is of the order of 1 : 1, which contrasts significantly with the 20: 1 ratio specified in US 5,282, 324.

In a further preferred embodiment of the invention the under-foot layer includes a respective said secondary air flow channel interconnecting a periphery of the layer and each branch of the branched flow path.

This arrangement allows the ingestion of fresh air to take place even if one of the branches of the primary air flow path is blocked.

In another optional arrangement the under-foot layer includes at least one secondary air flow channel interconnecting the further air chamber, that acts as an inlet to the pump, and a portion of the primary air flow channel.

More particularly such a secondary air flow channel may optionally interconnect the further air chamber and each branch of the branched flow path if required.

The advantage of this arrangement is to improve the aerodynamic efficiency of the arrangement.

Aerodynamic losses can be minimised by making the air channels as big as

possible and by creating as many air channels as possible. Against this, the designer must weigh the space available and the need to support the foot effectively.

By using the same inlet for both the pump and the secondary air flow channels, the designer can minimise the losses in each. The operation of the invention allows this because as described in more detail below a pump forming part of the invention and the secondary air flow channels do not draw air at the same time. The pump can be arranged to draw air when the foot leaves the ground, and the secondary air channels are active when air is released from the pump into the channels, usually when the foot hits the ground.

Regardless of the precise arrangement of the plurality of air flow channels, each said flow channel preferably includes a recess formed in a face of the layer that is in use remote from the said foot chamber, the said face in use of the layer overlying a further face of the footwear item so as to define substantially closed air flow channels.

The forming of the air flow channels as open recesses in the underside of an under-foot layer advantageously permits their formation by impress moulding into a surface of eg. a midsole. The air flow channels may then be formed as substantially closed channels (that are open essentially only at their ends) once the under-foot layer is assembled into a shoe such that the face of the under-foot layer that is in use remote from the foot chamber of the shoe overlies eg. an upper surface of an outer sole.

In an alternative arrangement the plurality of air flow channels may be defined by a network of interconnected pipes, the said network in use lying between upper and lower layers of a footwear insole.

This arrangement does not rely on positioning of the insole relative to eg. an outer sole surface in order fully to define the air flow channels; but nonetheless the manufacture of a series of pre-formed pipes is likely to be more expensive and time-consuming than the moulding of a series of recesses in a surface of an under-foot layer such as an insole or a midsole portion.

In one embodiment of the invention the under-foot layer includes a respective reversible valve for valving the or each said further channel.

Optionally the under-foot layer may include a respective reversible valve for valving the or each said supply channel when present.

Typically the valves are at the ends of the channels although this need not necessarily be so.

The purpose of the aforesaid valves primarily is to provide for a one way flow of eg. air along the air flow channels. Nonetheless in preferred embodiments of the invention the or each said reversible valve may optionally include one or more valving members that are biassed to open more readily during gas flow through the valve in a forward direction than during gas flow through the valve in a reverse direction.

This arrangement allows the exhausting of gas pressure from within a portion of a footwear channel, in the event of an intended air flow path becoming blocked.

A particularly preferred arrangement for each valving member includes a resiliently deformable membrane having formed therein a slit that divides the valving member into respective flaps that abut one another when the valve is closed, the said membrane defining a dome that normally protrudes

in the forward direction of flow, the flaps being forceable to reverse the direction of protrusion of the membrane when it is subjected to a force greater than a threshold value acting in the reverse direction of gas flow.

This arrangement is advantageously cheap to manufacture and effective in use.

Conveniently when present the first air chamber includes an interior surface having formed thereon one or more formations for reducing turbulence in air in the first chamber.

Preferably the formations include one or more ribs that protrude from the said interior surface. It is also preferable that the interior surface lies in the path of air conveyed from a said pump when the first air chamber is connected to an outlet thereof.

The foregoing features ad\antageously minimise air turbulence in the first air chamber, in a manner described in more detail below.

The formations on the aforesaid interior surface of the first air chamber increase the flow of air into the primary air flow channels by up to 15%, compared with an air chamber that omits the ribs.

According to a second aspect of the invention there is a provided a gas pump comprising an inlet, a pumping chamber and a pressure plenum, the inlet being connectable to the pumping chamber via a first valve so as to permit a flow of gas from the inlet to the pumping chamber and prevent the flow of gas from the pumping chamber to the inlet; the pumping chamber being connectable to the pressure plenum via a second valve so as to permit the flow of gas from the pumping chamber to the pressure plenum and prevent the flow of gas from the pressure plenum to the pumping chamber;

the pumping chamber including one or more moveable members for causing : (i) ingestion of gas via the inlet and the second valve; (ii) pressurisation of gas in the pumping chamber; and (iii) expulsion of gas via the second valve to the pressure plenum; and the pressure plenum including an outlet, for pressurised gas, that is normally closed by a pressure operated, openable valve whose operating pressure is for a chosen gas greater than that generated during a single stroke of the moveable components of the pumping chamber.

Such a gas pump may advantageously be arranged so that pressurised gas discharges from the pressure plenum only when the pressure therein corresponds to a gas discharge velocity that is perceptible at the toes of a wearer of a footwear item incorporating the gas pump. Accordingly, the gas pump of the invention obviates the disadvantages evident in the prior art, of the aeration of the wearer's toes being imperceptible.

Preferably the gas pressure required to cause opening of the pressure operated valve is greater than the pressure required to maintain the pressure operated valve in an open state after opening.

This arrangement advantageously ensures complete or substantially complete emptying of the pressure plenum after opening of the pressure operated, openable valve. This in turn advantageously ensures that a maximal volume of pressurised air is conveyed to the toes of the wearer of a footwear item incorporating the pump.

In particularly preferred embodiments of the invention the pressure operated valve is a so-called septum valve, that is a valve comprising a perforated, deformable membrane. The material and dimensions of the membrane are

selected so as to permit opening of the perforation therein only when the pressure acting on the membrane exceeds a threshold value.

Conveniently the pump chamber includes a housing having at least one resiliently deformable portion defining a said moveable member, deformation of the said deformable portion in a first direction against the resilience thereof causing pressurisation of gas in the pumping chamber and expulsion of gas via the second valve to the pressure plenum; and restoration of the deformable portion in a second direction that is assisted by the resilience thereof causing ingestion of gas into the pumping chamber via the inlet and the first valve.

This arrangement suits the gas pump of the invention for foot actuation within a shoe or other footwear item.

In preferred embodiments the septum valve includes a resiliently deformable membrane that is secured about its periphery across an aperture, the membrane being discontinuous so as to include a multi-cuspid valve flap arrangement that in the closed condition of the valve defines a dome that protrudes towards the pressure plenum of the gas pump and that in the open condition of the valve projects away from the pressure plenum.

More specifically, in the closed condition of the septum valve the dome preferably protrudes approximately 5mm towards the pressure plenum when measured from the said aperture and is circular having a base diameter of approximately 16mm, the membrane being formed from approximately 4.5mm thick, laminar, thermoplastic polyurethane having a Young's Modulus of approximately 3Mpa (3xlON/m2).

These features are particularly desirable in a pump intended for use within a footwear item.

Conveniently the gas pump includes a perforated mounting plate, the inlet and the pressure plenum being defined adjacent one another by respective housing members that are upstanding on one side of the mounting plate; and the pumping chamber being defined by one or more housing members that are upstanding on the opposite side of the mounting plate, the inlet being connectable to the pumping chamber via a first perforation through the mounting plate and the pumping chamber being connectable to the pressure plenum via a second perforation through the mounting plate.

This arrangement confers ease of manufacture and robustness on the gas pump, the components of which may be secured together eg. by welding.

Conveniently the first and second valves are operable to valve respectively the first and second perforations. This arrangement is advantageously compact and simple.

According to a third aspect of the invention there is provided a footwear item comprising one or more members defining an upper, including a ball/toe region that is secured to a sole including at least one sole layer, the upper and the sole defining a foot chamber that contains an under-foot layer according to the invention as defined herein arranged so as to permit aeration of the ball/toe region of the footwear item by means of conveyance of air via the plurality of channels and the further channel of the under-foot layer.

Such a footwear item offers advantages over the prior art, as discussed hereinabove.

Preferably the under-foot layer includes a first air chamber as defined herein that is operatively connected to the outlet side of a gas pump. It is also

preferable that the under-foot layer includes a further air chamber that is operatively connected to the inlet side of the said pump.

In preferred embodiments of the invention the pump is a gas pump according to the invention as defined herein, the outlet of the said gas pump being operatively connected to the first air chamber of the under-foot layer and the inlet of the gas pump being operatively connected to the further air chamber thereof, the gas pump being arranged so that the gait of a wearer of the footwear item causes movement of the moveable member thereof to cause: (i) conveyance of air, via the plurality of air flow channels and the further channels that perforate the under-foot layer, between the ball/toe region of the footwear item and the said portion of the under-foot layer that is remote from the ball/toe portion thereof ; and (ii) ingestion of air via the or each supply channel for conveyance via the plurality of air flow channels.

The principle of using the gait of the wearer of the footwear item to operate the gas pump is, as noted, known in itself. The use of such an arrangement in a footwear item having an under-foot layer and a pump as specified herein is nonetheless advantageous with respect to the prior art, for the reasons stated herein.

Preferably the footwear item includes a heel having a recess having received therein the gas pump.

This advantageously utilises a conventional feature of the shoe for containing a functional component.

In preferred embodiments of the invention the under-foot layer and the sole are releasably securable together to permit removal of the under-foot layer

from the footwear item.

This permits removal of the under-foot'layer for cleaning and/or replacement.

More specifically the footwear item optionally includes a pressure actuated seal between the under-foot layer and the insole, the said seal being actuatable by foot pressure acting on the under-foot member.

This arrangement is particularly advantageous since it obviates the need to create a high-performance seal during manufacture of the footwear item.

On the contrary the foot pressure applied by the user is sufficient to achieve an adequate seal, in use, that is breakable to permit removal of the underfoot layer from the footwear item.

One preferred arrangement for creating the pressure-actuated seal is by the inclusion of one or more regions of a substantially gas impermeable, lowtack adhesive material coated on the under-foot layer and/or on the sole adjacent the in use positions of the plurality of air channels and the supply channels so as to seal the sole about the said channels to permit conveyance of air therein.

In preferred embodiments the coated adhesive is the result of a screen printing process. More preferably the adhesive is or includes eg. coagulated polyurethane resin or coagulated latex.

In an alternative arrangement the low tack adhesive material can be moulded directly to the material of the insole using soft a TPE (thermoplastic elastomer) such as a soft PVC. An example is the TPE "Engage"manufactured by DuPont Dow Elastomers. In other embodiments tetraphenylurethanes may be suitable.

In a further, optional arrangement the under-foot layer may include for example raised ribs adjacent the air flow channels and the supply channels and/or areas of a low-hardness material adjacent the air flow channels and the supply channels, in order to promote a better seal with the low-tack adhesive coated onto the insole member.

Preferably the material of the under-foot layer is or includes blown polyurethane, ethyl vinyl acetate and/or polyethylene. This material is highly suitable for use in the manufacture of eg. under-foot layers such as footbeds.

In a fourth, broad aspect according to the invention there is provided the use of a septum valve to control the release of pressurised gas in a chamber forming part of a footwear item.

There now follows a description of preferred embodiments of the invention, by way of non-limiting example, with reference being made to the accompanying drawings in which: Figure 1 is a plan view from underneath of a first embodiment of under-foot layer according to the invention ; Figure 2 is a plan view from underneath of a second embodiment of under-foot layer according to the invention; Figure 3 is a plan view from below of a third embodiment of underfoot layer according to the invention; Figure 4 is a side elevational view of the under-foot layer of Figure 3; Figure 5 is a cross-sectional view of the Figure 3 layer, taken on line 5-5; Figure 6 shows an alternative construction of under-foot layers according to the invention;

Figure 7 shows the Figure 6 arrangement in a partly assembled condition in order to illustrate the possible locations of one way valves in the air channels thereof ; Figures 8a to 8d show valves that are suitable for use in under-foot layers according to the invention ; Figure 9 shows in cross sectional view a gas pump according to the invention; Figure 10 shows in partly sectioned view a septum valve forming part of the Figure 9 pump; Figure 11 shows a partly assembled footwear item according to the invention; Figure 12 shows a footwear item according to the invention, following completion of the manufacturing process; and Figure 13A and 13B illustrate the efficacy of the invention when in use to aerate a person's toes.

Referring to the drawings there is shown in Figure I an under-foot layer 10 that is suitable for use in a footwear item such as but not limited to that described in more detail hereinbelow.

Under-foot layer 10 is in the embodiment shown a so-called footed, ie. a flexible, resiliently deformable layer that in a completed shoe lies sandwiched between eg. an insole and an outer sole or a midsole.

The under-foot layer of the invention need not be constructed as a footed. The features of the invention may readily be incorporated into eg. a midsole or an insole.

Figure 1 shows an underneath plan view of the underfoot layer 10. Layer 10 includes a ball/toe portion 11 and a heel portion 12, the portions 11, 12 being interconnected by an arch portion 13.

Under-foot layer 10 is, as indicated, in use intended to lie beneath a foot chamber defined in a footwear item by one or more uppers that typically are stitched or otherwise secured together and secured to a sole.

The underside face 14 of under-foot layer 10 that is in use remote from the foot chamber has formed therein a plurality of primary air flow channels 16 that extend between the ball/toe region 11 and the heel portion 12, ie. a portion of the under-foot layer 10 that is remote from the ball/toe region 11.

In the ball/toe region the under-foot layer 10 is perforated by one or more further channels 17. One or more of the plurality of primary air flow channels 16 communicates with each said further channel so as to provide an air flow path from the underside of the under-foot layer 10 to the upper side thereof.

In the embodiment shown in Figure 1 the primary air flow channels are shaped substantially to follow the outline of the under-foot layer 10. The further channels 17 comprise a series of four perforations, although of course other arrangements and patterns of the primary air flow channels 16 and the perforations 17 are possible within the scope of the invention.

At least one, and in practice both, the air flow channels 16 shown in Figure 1 are operatively connected to a pump (not shown in Figure 1) for conveying air along the air flow channels 16 and via the further channels 17 to the ball/toe portion of the under-foot layer 10 from eg. the heel portion 12, the resulting flow path including at least one branch represented in Figure 1 by the dividing wall 18 in the heel portion 12 thereof.

This arrangement ensures that there is more than one primary air flow channel extending between eg. the heel portion and the ball/toe portion of

the under-foot layer. This in turn virtually eliminates the possibility of the air flow path between the heel and the ball/toe region becoming blocked in use eg. by virtue of the gait of a user.

In the embodiment shown in Figure !, the branched primary air flow channels 16 meet in the heel portion 12 in a first air chamber defined as a recess formed in face 14 so that it is spaced from the ball/toe region 11.

First air chamber 21 is thereby in fluid communication with the plurality of primary air flow channels 16. First air chamber 21 is shaped for connection to the outlet of a gas pump.

Under-foot layer 10 includes formed therein in face 14 a series of air supply channels 19 for supplying air to such a pump.

In the arrangement shown there are four such air supply channels 19, that extend from an edge 22 of under-foot layer 10 towards a further air chamber 23 that is, like air chamber 21, formed as a recess in face 14.

The thickness of under-foot layer 10 is not constant.

In the vicinity of edge 22 the thickness is at its greatest. The air supply channels 19 each terminate in a perforation 19a that extends upwardly and is open on edge 22 to provide for the ingestion of air towards further air chamber 23 in a manner shown below.

Although in Figure 1 there is shown a"crow's foot"pattern of four supply channels 19, in other embodiments of the invention different numbers and patterns of the supply channels 19 are possible.

As shown in Figure 1, the two primary air flow channel branches 16a, 16b

are connected at the forwardmost end of the ball/toe region 11 to define the primary air flow channels 16 as a loop, the forwardmost part of which is in fluid communication with the further channels 17.

Referring now to Figure 2 there is shown a second embodiment of under- foot layer 10 according to the invention.

The under-foot layer 10 of the Figure 2 embodiment is similar to the Figure 1 embodiment in that it comprises a laminar member of non-constant thickness. The in use lowermost face 14 of layer 10 has formed therein a plurality of primary air flow channels 16, that interconnect a ball/toe portion 11 and a heel portion 12, with the primary air flow channels 16 being bifurcated by a dividing wall 18 at a location remote from the ball/toe portion 11; and with the primary air flow channels terminating eg. in the heel region 12 at a first air chamber 21 that is connectable to the outlet side of a pump.

The air supply channels 19 interconnect a peripheral edge of the under-foot layer 10 and a further air chamber 23 as shown.

The arrangement of Figure 2 additionally includes at least one secondary air flow channel 24 interconnecting a periphery of the under-foot layer 10 and a said primary air flow channel 16.

In practice each of the branches 16a, 16b of the primary air flow channel is connected by a respective secondary air flow channel 24a, 24b to the periphery of the under-foot layer 10.

In use of the apparatus of the invention the secondary air flow channels 24a, 24b permit the ingestion into the primary air flow channels 16 of fresh air that is additional to any pumped by the gas pump described in more detail

below.

This is in practice achieved through the use of a gas pump that pumps air in the primary air flow channels at a high velocity so as to cause a pressure drop in the vicinity of the connection of each secondary air flow channel to its associated primary air flow channel 16. Additional air is thereby introduced via the secondary air flow channels 24 according to a Bernoulli effect in which pressure in the primary air flow channels reduces and thereby causes entrainment of air in approximately a ! : 1 ratio to the volume of air pumped by the pump.

The merging of the secondary air flow channels 24a, 24b with the associated primary air flow channels is shaped as shown so as to encourage the flow of air towards the ball/toe region 11 of the under-foot layer 10.

Also as shown in Figure 2, secondary air flow channel 24b is bifurcated by a wall 26 spaced a short distance from the rear peripheral edge of heel region 12.

In the embodiment of Figure 2 there are shown five of the further air flow channels 17 in a series in the portion of the primary air flow loop defined by the primary air flow channels 16 adjacent the forwardmost end of heel/toe region 11.

Figure 3 shows yet a further variant of under-foot layer 10 according to the invention.

Under-foot layer 10 of Figure 3 differs from the arrangement of Figure 2 in that the secondary air flow channels 27 interconnect the further air chamber 23 and each respective branch 16a, 16b of the primary air flow channel 16, instead of connecting the primary air flow channels to the peripheral edges

of the under-foot layer 10.

The function of this arrangement is to improve the aerodynamic efficiency of the arrangement, as specified hereinabove.

Figure 4 is a side elevational view of the under-foot layer 10 of Figure 3, viewed in the direction facing the termination of the supply channels 19 at the peripheral edge of the layer.

As shown in Figure 4, the thickness of the under-foot layer 10 is in this region at its greatest. Each of the air supply channels 19 terminates in an upstanding perforation 28 that is open on the upstanding edge 29 of layer 10, so as to provide for ingestion of air via the channels 19.

When the under-foot layer 10 is in use in a footwear item, the open channels 28 may terminate eg. in the foot chamber thereof ; or they may simply lie adjacent a gas-permeable part of the shoe upper so as to allow for the ingestion of air.

Figure 5 is a cross sectional view on line 5-5 of Figure 3, showing that the various channels formed in the underside 14 of under-foot layer 10 are in the preferred embodiments of Figures 1 to 3 formed as recesses. The chambers 21,23 are similarly formed as recesses, with in preferred embodiments the upper boundary wall of chamber 21 having formed thereon a plurality of ribs 31. The function of the ribs 31 is to minimise turbulence.

When the pump described below emits air it emerges as a jet, striking the aforesaid upper wall of chamber 21. From there the air rebounds in all directions. By shaping the top surface of the chamber as shown, the energy in the air is more effectively contained, the turbulence is diminished more

quickly and, as a result, more air is forced down the channels.

The cross sectional view in Figure 5 also shows a typical construction of the under-foot layer 10, that is of a soft, laminar layer 32 having bonded to its underside a series of blown or foamed layers 33,34, 36 defining face 14 and the features formed therein.

The materials from which the blown or foamed layers 33,34, 36 are made include but are not limited to so-called blown EVA and similar resiliently deformable, energy absorbing, flexible materials.

In use of the under-foot layer of Figures I to 5 the face 14 is placed in contact with a further layer such as the upper surface of a midsole, such that the latter presses against and closes the open channels defined by the recesses. As a result the channels are open eg. only at their terminations at the edges of the under-foot layer 10, thereby providing for conveyance of air.

This method of defining the various air flow channels and chambers is advantageously simple and economical to achieve, as is evident from the straightforward construction exemplified in Figure 5 of the drawings.

An alternative approach to defining the air flow channels in the under-foot layer is shown in Figure 6.

In Figure 6 the under-foot layer 10 is defined as a sandwiched construction in which upper 37 and lower 38 insole layers of substantially mutually congruent shape have sandwiched therebetween a pre-formed network 39 of air flow channels.

The network 39 of the channels 16,17, 19, etc. may be pre-formed, eg. by

moulding from a plastic material.

This creates a discrete component 39 that may for example include a pump represented schematically at 41. Pump 41 is connected so as to ingest air via the supply channels 19, pump it via the primary air flow channels 16 and eject it via the further channels 17 defined as perforations in the pipes forming part of the component 39.

The moulding of the network 39 from a plastic material as aforesaid allows if desired the use of a largely permeable material (or combination of materials) for manufacture of the remainder of the layer 10.

When layer 10 is configured as a footed, a pressed felt or similar nonwoven construction is thereby made possible, as are the moulding of layer 10 as a highly porous foam; or even a highly perforated plastic layer.

The upper insole layer 37 may have formed therein apertures 42 or regions of permeability corresponding to the locations at which air enters and leaves the network of pipes defined by the component 39.

The pump 41 is such that the pressure of a human foot during a normal walking action actuates it to pump air as aforesaid.

The upper surface of lower insole layer 38 may have coated thereon a region of adhesive or sealing material 43 for the purpose of securing the component 39 thereto.

In another arrangement the substantially closed pipes 42 of the component 39 may be formed as a series of channels that are open on the side of component 39 that in use adjoins the upper surface of layer 38. In this arrangement the coating of sealing and/or adhesive compound indicated at

43 serves, in addition to its securing function, to close the open channels and define the air flow paths.

Any of the embodiments of the under-foot layers 10 described herein may include in their channels one or more one way valves referred to herein as "reversible valves".

Figure 7 shows in plan view an arrangement of pipes or channels similar to that shown in Figure 6, and showing by means of arrows 44 the preferred inlet and outlet paths of air in use.

Reversible valves as disclosed hereinbelow may be incorporated for example at the locations 45 shown in Figure 7.

Figures 8a to 8d show one form of reversible valve suitable for use at such locations.

In Figures 8a to 8d there is shown an aperture 46 such as may be defined at the termini of the various air flow channels 16,19 formed in the under-foot layers 10 eg. of Figures I to 7.

Each aperture 46 is normally closed by a membrane 47 secured eg. by welding or by means of an adhesive so as to overlie the aperture.

The membrane 47 has a peripheral region 49 by means of which it is secured as aforesaid to the region of the material external to the aperture 46.

The region 48 of the membrane 47 that overlies the opening defined as the aperture 46 is in the preferred embodiment dome-shaped so as to protrude into the air flow channel terminated at the aperture 46.

The protruding part of membrane 47 need not be domed, however. Other shapes including but not limited to eg. conical, sectioned conical and pyramidal shapes are also possible.

In the preferred embodiment shown the domed portion 48 of the membrane 47 has formed therein a slit 51 such that the domed portion 48 defines a pair of valve flaps that abut one another in the closed position of the valve.

The membrane 47 is, at least in the vicinity of domed portion 48, formed from a flexible and preferably resiliently deformable material. In normal use of the under-foot layer 10 in a footwear item, air would flow in the direction of arrow 52 visible in Figure 8b. The direction represented by arrow 52 is such as to separate the valve flaps along the line of slit 51 by a motion that may be considered as exaggerating the domed shape thereof.

Consequently when air flows in the direction of arrow 52 (ie. the intended direction of air flow) it is comparatively easy for the mass of air to open the reversible valve defined by membrane 47.

Possibly on occasions air pressure may act in the opposite direction to that represented by arrow 52, as signified by arrow 53 in Figure 8c. This may occur eg. in the air supply channels 19 in the unlikely event of failure of the pump to pump air forwardly towards the ball/toe region along the primary air flow channels 16.

Since the membrane 47 presents a dome shape protruding into the air flow channel, the valve defined thereby tends to resist the flow of air in the direction signified by arrow 53, to a greater extent than when the air flows in the direction signified by arrow 52.

However, as indicated in Figure 8d, when the air pressure indicated by arrow 53 exceeds a limit value the valve flaps defining the domed shape of

portion 48 of membrane 47 turn inside out. The result of this is that the valve opens to allow the dumping of excess pressure from the air flow path, without causing damage to the other components of the under-foot layer or causing discomfort to a user thereof or making a noise.

If as in preferred embodiments the membrane 47 is constructed from a resiliently deformable material, following relieving of the pressure represented by arrows 53 the membrane 47 is restored by the resilience of the material to its domed shape as visible in Figure 8a.

Consequently the reversible valve shown in Figures 8a to 8b is such as normally to close its associated channel; and to open to permit gas flow in a forward direction at a lower gas pressure than that at which it opens to permit gas flow in a reverse direction.

Referring now to Figure 9 there is shown in cross sectional view a gas pump, according to the invention, that is suitable for use in conjunction with an under-foot layer according to the invention in a footwear item.

Gas pump 54 includes a housing 56 that is subdivided internally to define a series of chambers.

Housing 56 is formed protruding to either side of a laminar mounting plate 57 that in preferred embodiments of the invention facilitates construction thereof.

Gas pump 54 includes an inlet chamber 58 comprising a plurality of walls 59 that are upstanding from the in use upper side of mounting plate 57.

Inlet chamber 58 terminates at its uppermost end in an opening 61 that is operatively connectable in use of the gas pump 54 to further air chamber 23 of under-foot layer 10 as shown in any of Figures 1 to 5.

A plurality of walls 62 protrude from the in use lower side of mounting plate 57 to define a pumping chamber 63 to which inlet chamber 58 is connectable via an aperture 64 that perforates mounting plate 57 adjacent the lowermost end of inlet chamber 58.

A first valve 66 that in the preferred embodiment is a simple one way flap valve of per se known design normally closes perforation 64. First valve 66 is a one way valve that is openable to permit air flow from inlet chamber 58 to pumping chamber 63. First valve 66 prevents the flow of gas in a reverse direction from pumping chamber 63 to inlet chamber 58.

A plurality of further walls 67 are upstanding from the in use upper side of mounting plate 57, adjacent inlet chamber 58, to define a pressure plenum 68.

Pumping chamber 63 is connectable via a second perforation 69 formed in mounting plate 57 to pressure plenum 68.

Second perforation 69 is normally closed by a second valve 71 that is of essentially the $ame construction as first valve 66.

Second valve 71 is arranged to permit one way flow of air from pumping chamber 63 into pressure plenum 68; and to prevent reverse flow of air from pressure plenum 68 to pumping chamber 63.

Peripheral portions 72 of the walls defining pumping chamber 63 are in the embodiments shown of flexible bellows construction so as to define, with a comparatively rigid rigid plate 73 forming the lowermost part of pump 54, a moveable member that is reciprocable towards and away from mounting plate 57 to operate the pump 54.

More specifically, at least the bellows portions 72 of the walls defining the pumping chamber 63 are resiliently deformable. The resiliently deformable nature of the portions 72 tends to cause the pumping chamber 63 to adopt the cross sectional shape shown in Figure 9.

On compression of the entire pump 54, as would occur during walking when the pump 54 is incorporated into a footwear item, comparatively rigid plate 73 moves towards mounting plate 57 against the resilient deformability of the bellows-like portions 72 to pressurise air in pumping chamber 63.

The pressure of such pressurised air in pumping chamber 63 acts to force the flap of first valve 66 into seating engagement with first perforation 64, to prevent the flow of pressurised air from pumping chamber 63 into inlet chamber 58.

On the other hand the resulting air pressure tends to open the flap of valve 71 so that the pressurised air in pumping chamber 63 is expelled via second valve 71 into pressure plenum 68.

The uppermost wall of pressure plenum 68 is perforated by an aperture 74 defining an outlet for pressurised gas. Aperture 74 is normally closed by a pressure operated, openable valve indicated schematically in Figure 9 by reference numeral 76.

Since aperture 74 is normally closed, the pumping stroke of the pumping chamber 63 tends to charge pressure plenum 68 with pressurised air.

On releasing of compressive force from the housing of pump 54, plate 73 is restored to the position visible in Figure 9 by virtue of the resilience of the

bellows portions 72.

As this happens the pressurised air now in pressure plenum 68 closes valve 71. The movement of plate 73 reduces pressure in pumping chamber 63. This in turn opens first valve 66 to allow re-charging of pumping chamber 63 via inlet chamber 58.

The pressure operated valve 76 is openable only when the pressure in pressure plenum 68 exceeds a threshold value that is greater than the pressure attainable in pumping chamber 63 during the pumping stroke thereof. Consequently it requires more than one stroke of pumping chamber 63 to charge pressure plenum 68 to a pressure that is sufficient to open pressure operated valve 76.

Through judicious choice of the design of valve 76 and the other components of the pump 54, it is possible to arrange for the valve 76 to open eg. following say five strokes of the pumping chamber 63 in the manner aforesaid. When the perforation 69 is connected to the first air chamber 21 of an under-foot layer 10 as described herein such an arrangement leads to the discharging of a high velocity stream of air into the primary air flow channels 16 for example every fifth time (or some other number of times) that a user thereof plants his foot during a normal walking gait.

This in turn leads to the periodic aeration of the ball/toe region of the footwear item in which the pump is installed, with a readily perceptible, fast-moving volume of air. Consequently the disadvantage in the prior art, of the flow of aerating air being imperceptible to a wearer, is overcome.

Figures 13A and 13B illustrate this effect.

Figure 13A shows that the regular, weak air pulses 55a, that are characteristic of the prior art arrangements, are inadequate to displace moist air 60 from a shoe wearer's sock 65 in the vicinity of his toes. This is principally the result of a boundary layer effect as illustrated schematically in Figure 13A. Consequently the shoe wearer does not feel the air pulses 55a.

Figure 13B shows that a periodic gust 55b of greater volume and higher velocity than pulses 55a destroy the boundary layer of moist air 60. This allows the wearer to feel the gust 55b and also produces a cooling effect caused by evaporation of moisture.

Figure 10 shows in more detail the valve 76 of the Figure 9 arrangement.

Valve 76 is a so-called septum valve comprising a resiliently deformable membrane 77 that is secured eg. by means of an annular clamp 78 about its periphery, so as to close aperture 74 formed in the uppermost wall of pressure plenum 68. Alternative means of securing the membrane 77 over aperture 74 include but are not limited to welding, adhesives or (in the case of compatible materials) co-moulding with the housing wall that defines the aperture 74.

Membrane 77 is formed from a dome-shaped lamina of resiliently deformable material such as a natural or synthetic rubber, a soft TPE

(tetraphenylethylene) (eg. Santoprene 55 Shore A) or a silicon (eg. Silastic 55 U). The dome of membrane 77 protrudes into pressure plenum 68 in the closed position of the valve 76.

The protruding part of membrane 77 need not be domed, however. Other shapes including but not limited to eg. conical, sectioned conical and pyramidal shapes are also possible.

Membrane 77 is in the embodiment shown divided in at least one plane 79 extending parallel to its minor dimension, so as to form at least two valve flaps 77a, 77b.

The edges of the valve flaps 77a, 77b, abut one another in the closed position of the valve 76 shown in solid lines in Figure 10.

When the pressure in pressure plenum 68 exceeds a threshold value determined by the design of the components of valve 76, the dome shape reverses against the resilient defbrmability of the material of membrane 77 so that the valve flaps 77a, 77b separate from one another and protrude externally of the pressure plenum 68, as indicated in dotted lines in Figure 10.

In this open condition of the valve 76 the pressurised air discharges from the pressure plenum 68 into the network of air flow channels.

The design of the valve 76 is such that the threshold pressure necessary to open the valve flap 77a, 77b to the position shown in dotted lines in Figure 10 is greater than the pressure needed to maintain the flaps in this position after opening. Consequently the valve 76 stays in an open condition even after the pressure in plenum 68 has started to decay as the air discharges.

Once complete or substantially complete discharge of the air from plenum 68 has occurred, the resilient nature of the flaps 77a, 77b defined in membrane 77 causes them to revert to the domed, closed position shown in solid lines in Figure 10.

In one embodiment of gas pump 54 according to the invention the volume of the pressure plenum is approximately 6 cm3. The threshold pressure

needed to open the valve 76 is 250 kPa. The discharge coefficient is calculated as 0.6. The thickness of the lamina 77 measured along its minor, transverse dimension is 4.5 mm and the diameter of aperture 74 is 16 mm.

In practice the membrane 77 is divided by two, mutually perpendicular planar cuts each similar to that represented by reference numeral 79, so as to define a quadrucuspid valve having four valve flaps.

Other designs of valve, that need not necessarily be of the so-called "septum"type, are possible within the scope of the invention.

Figures 11 and 12 show in partly and fully assembled condition typical components according to the invention, as assembled into a footwear item shown as an exemplary shoe 81.

Shoe 81 includes a plurality of panels secured together to define an upper 82 defining a foot chamber 83 including a ball/toe region 84 at the forwardmost end thereof.

Upper 82 is secured to a sole 86 that includes one or more sole layers and (in the embodiment shown) a substantially conventionally shaped heel 87.

The precise shape of shoe 81 shown is for illustrative purposes only. The components thereof may take any of a wide range of other forms within the scope of the invention.

An under-foot layer 10 according to the invention is received within the foot chamber 83 overlying the uppermost layer 88 of sole 86 as best shown in Figure 11.

Figure 11 shows the manner of positioning of under-foot layer 10 onto

uppermost layer 88. In practice during assembly of a shoe 81 the step exemplified by Figure 11 would not occur until after formation of the upper 82 and securing thereof to the sole 86. Upper 82 has been omitted from Figure 11 for clarity purposes only.

Under-foot layer 10 is, as illustrated by arrows 89, inserted onto layer 88 with its lower face 14 in contact with layer 88.

As is evident from Figures 11 and 12, a pump 54 according to the invention is received within an aperture formed in heel 87. The inlet chamber 58 and outlet perforation 74 of pump 54 are positioned such that on placing of under-foot layer 10 as described the first air chamber 21 overlies and is in fluid communication with perforation 74; and further air chamber 23 overlies and is in fluid communication with air inlet chamber 58.

The features of under-foot layer 10 and pump 54 are arranged so that the peripheries of the chambers 21,23 seal about the perforation 74 and the inlet 58 so as to permit the pumping of air by the pump into the primary air flow channels 16 for the purpose of aerating the ball/toe region of shoe 81, with the pump being charged by air drawn in via the supply channels 19 of under-foot layer 10.

Since in the preferred embodiment the under-foot layer 10 is not rigidly secured relative to the foot chamber defined in shoe 81, during a normal walking action the planting of the user's foot will cause compression of the pump 54 to operate the pump. Lifting of the foot during the normal gait will allow restoration of the pump from its compressed state, to cause recharging of the pump via the inlet chamber 58.

The flow of air into the pump via the supply channels 19 and the inlet chamber 58 is signified by arrow 89 in Figures 11 and 12. The flow of

pumped air that causes aeration of the ball/toe region 84 is signified by arrows 91 and 92.

Since the action of septum valve 76 is as described herein, air will flow as signified by arrow 89 with each step taken; whereas air will only flow along the path represented by arrows 91 and 92 for example every fifth step (or at some other interval), determined by the precise design of the septum valve 74 and the pressure plenum 68.

Layer 10 and the upper layer 88 of sole 86 preferably are releasably secured together to permit removal of the layer 10 from the shoe 81.

One way of achieving removable securing of the under-foot layer 10 is by means of a pressure actuated seal between the face 14 of layer 10 and the layer 88 of sole 86. Preferably such a layer is actuatable by foot pressure during use of the shoe 81 for walking, whereby the seal becomes fully tight as a result of the user's weight acting downwardly on the layer 10. One way of achieving this effect is by coating one or more regions of a substantially gas-impermeable, low tack adhesive material on either the under-foot layer 10 and/or the layer 88 of sole 86 so as to surround the inuse positions of the various air channels 16,19. In practice such a coating of a low tack adhesive may occupy for example the approximate positions signified by the arrows 91 in Figure 12.

By"low tack adhesive"is meant a substance that temporarily bonds with the material of face 14 oflayer 10. This need not necessarily be a material that is conventionally recognised as having adhesive properties.

Consequently preferred materials for the low tack adhesive may be eg. a coagulated polyurethane resin or a coagulated latex (natural rubber). Such materials may be applied to the chosen surface 14 or 88 eg. by means of

screen printing. In another embodiment of the invention a soft TPE material may be moulded directly eg. onto the upper surface of layer 88.

Regardless of the precise adhesive chosen, in preferred embodiments of the invention it is such that the seal it creates becomes semi-permanent after a short period of wearing of the shoe.

By"semi-permanent"is meant a seal that does not cease to exist when the wearer lifts his foot or removes the footwear item from his foot. On the other hand the low-tack adhesive preferably is such that it unseals when the user deliberately grasps the under-foot layer for the purpose of removing it.

In some embodiments of the invention the adhesive is such that a few walking paces are sufficient to establish the semi-permanent seal. In other embodiments the tack of the adhesive is such that the fitting of the footwear item onto a foot is, by virtue of the tension in eg. laces or other fasteners, the elasticity of the components of the footwear item and the flexibility of the wearer's foot, sufficient to create at least an initial seal (that may subsequently be enhanced during walking).

Optionally the face 14 of layer 10 may include embossments, ribs or other features such as regions of softer material to enhance or promote good sealing between the face 14 and the layer 88 so as effectively to close the sides of the channels formed in face 14 to define the air flow channels 16,19.

Claims

1. An under-foot layer of a footwear item the under-foot layer comprising a ball/toe portion and a heel portion that are interconnected by an arch portion, the layer in use in a footwear item lying beneath a foot chamber defined by one or more uppers, a face of the layer that is in use remote from the said foot chamber having formed therein a plurality of air flow channels extending between the ball/toe portion and a portion of the layer remote therefrom for conveying air between the said portions, at least one said channel communicating with one or more further channels that perforate the layer in the ball/toe region and at least one said channel in use of the layer being connectable to a pump for causing conveyance of air to the ball/toe portion from the said portion of the layer remote therefrom via a branched flow path defined in the said plurality of channels.

2. An under-foot layer according to Claim 1 including formed therein a first air chamber that is spaced from the said ball/toe region and that is in fluid communication with the said plurality of air flow channels, the first air chamber being connectable to the outlet side of a pump for conveying air.

3. An under-foot layer according to Claim 1 or Claim 2 including formed therein at least one supply channel for supplying air to a pump to which the layer is connectable.

4. An under-foot layer according to Claim 3 including a plurality of supply channels formed in the said face of the layer that is in use remote from the said foot chamber.

5. An under-foot layer according to Claim 3 or Claim 4 wherein the or each said supply channel interconnects a periphery of the layer and a further air chamber that is connectable to the inlet side of a pump for conveying air.

6. An under-foot layer according to Claim 2 or any claim dependent therefrom wherein the plurality of air flow channels includes a primary air flow channel that is in communication with the first air chamber and that extends therefrom towards the ball/toe region, the primary air flow channel being bifurcated at a region remote from the ball/toe region to define at least two air flow branches.

7. An under-foot layer according to Claim 6 wherein the two air flow branches are interconnected to define an air flow loop.

8. An under-foot layer according to Claim 6 or Claim 7 including at least one secondary air flow channel interconnecting a periphery of the layer and a part of the primary air flow channel.

9. An under-foot layer according to Claim 8 including a respective said secondary air flow channel interconnecting a periphery of the layer and each branch of the branched flow path.

10. An under-foot layer according to Claim 5 and Claim 6, the layer including at least one secondary air flow channel interconnecting the said further air chamber and a portion of the primary air flow channel.

11. An under-foot layer according to Claim 10 including a respective said secondary air flow channel interconnecting the said further air chamber and each branch of the branched flow path.

12. An under-foot layer according to any preceding claim wherein each said flow channel includes a recess formed in a face of the layer that is in use remote from the said foot chamber, the said face in use of the layer overlying a further face of the footwear item so as to define substantially

closed air flow channels.

13. An under-foot layer according to any of Claims 1 to 11 wherein the plurality of air flow channels are defined by a network of interconnected pipes, the said network in use lying between upper and lower layers of a footwear insole.

14. An under-foot layer according to any preceding claim including a respective reversible valve for valving the or each said further channel.

15. An under-foot layer according to Claim 3 or any claim dependent therefrom including a respective reversible valve for valving the or each said supply channel.

16. An under-foot layer according to Claim 14 or Claim 15 wherein the or each said reversible valve normally closes its associated further channel or supply channel and opens to permit gas flow in a forward direction at a lower gas pressure than that at which it opens to permit gas flow in a reverse direction.

17. An under-foot layer according to any of Claims 14 to 16 wherein the or each said reversible valve includes one or more valving members that are biassed to open more readily during gas flow through the valve in a forward direction than during gas flow through the valve in a reverse direction.

18. An under-foot layer according to Claim 17 wherein each said valving member includes a resiliently deformable membrane having formed therein a slit that divides the valving member into respective flaps that abut one another when the valve is closed, the said membrane defining a dome that normally protrudes in the forward direction of flow, the flaps being forceable to reverse the direction of protrusion of the membrane when it is

subjected to a force greater than a threshold value acting in the reverse direction of gas flow.

19. An under-foot layer according to Claim 2 or any of Claims 3 to 18 when dependent therefrom, the first air chamber including an interior surface having formed thereon one or more formations for reducing turbulence in air in the first chamber.

20. An under-foot layer according to Claim 19 wherein the formations include one or more ribs that protrude from the said interior surface.

21. An under-foot layer according to Claim 19 or Claim 20 wherein the said interior surface lies in the path of air conveyed from a said pump when the first air chamber is connected to an outlet thereof.

22. A gas pump comprising an inlet, a pumping chamber and a pressure plenum, the inlet being connectable to the pumping chamber via a first valve so as to permit a flow of gas from the inlet to the pumping chamber and prevent the flow of gas from the pumping chamber to the inlet; the pumping chamber being connectable to the pressure plenum via a second valve so as to permit the flow of gas from the pumping chamber to the pressure plenum and prevent the flow of gas from the pressure plenum to the pumping chamber; the pumping chamber including one or more moveable members for causing: (i) ingestion of gas via the inlet and the second valve; (ii) pressurisation of gas in the pumping chamber; and (iii) expulsion of gas via the second valve to the pressure plenum; and the pressure plenum including an outlet, for pressurised gas, that is normally closed by a pressure operated, openable valve whose operating pressure is for a chosen gas greater than that generated during a single

stroke of the moveable components of the pumping chamber.

23. A gas pump according to Claim 22 wherein the gas pressure required to cause opening of the pressure operated valve is greater than the pressure required to maintain the pressure operated valve in an open state after opening.

24. A gas pump according to Claim 23 wherein the pressure operated valve is a septum valve.

25. A gas pump according to Claim 22 or any claim dependent therefrom, wherein the pump chamber includes a housing having at least one resiliently deformable portion defining a said moveable member, deformation of the said deformable portion in a first direction against the resilience thereof causing pressurisation of gas in the pumping chamber and expulsion of gas via the second valve to the pressure plenum; and restoration of the deformable portion in a second direction that is assisted by the resilience thereof causing ingestion of gas into the pumping chamber via the inlet and the first valve.

26. A gas pump according to Claim 24 wherein the septum valve includes a resiliently deformable membrane that is secured about its periphery across an aperture, the membrane being discontinuous so as to include a multi-cuspid valve flap arrangement that in the closed condition of the valve defines a dome that protrudes towards the pressure plenum of the gas pump and that in the open condition of the valve projects away from the pressure plenum.

27. A gas pump according to Claim 26 wherein in the closed condition of the septum valve the dome protrudes approximately 5mm towards the pressure plenum when measured from the said aperture and is circular

having a base diameter of approximately 16mm, the membrane being formed from approximately 4.5mm thick, laminar, thermoplastic polyurethane having a Young's Modulus of approximately 3Mpa (3x106 N/m2).

28. A gas pump according to Claim 22 or any claim dependent therefrom including a perforated mounting plate, the inlet and the pressure plenum being defined adjacent one another by respective housing members that are upstanding on one side of the mounting plate ; and the pumping chamber being defined by one or more housing members that are upstanding on the opposite side of the mounting plate, the inlet being connectable to the pumping chamber via a first perforation through the mounting plate and the pumping chamber being connectable to the pressure plenum via a second perforation through the mounting plate.

29. A gas pump according to Claim 28 wherein the first and second valves are operable to valve respectively the first and second perforations.

30. A footwear item comprising one or more members defining an upper, including a ball/toe region, that is secured to a sole including at least one sole layer, the upper and the sole defining a foot chamber that contains an under-foot layer according to any of Claims 1 to 21 arranged so as to permit aeration of the ball/toe region of the footwear item by means of conveyance of air via the plurality of channels and the further channel of the under-foot layer.

31. A footwear item according to Claim 30 wherein the under-foot layer is according to Claim 5 when dependent from Claim 2; and wherein the first air chamber of the under-foot layer is operatively connected to the outlet side of a gas pump and the further air chamber of the under-foot layer is operatively connected to the inlet side of the said pump.

32. A footwear item according to Claim 31 wherein the said pump is a gas pump according to any of Claims 22 to 29, the outlet of the gas pump being operatively connected to the first air chamber of the under-foot layer and the inlet of the gas pump being operatively connected to the further air chamber thereof, the gas pump being arranged so that the gait of a wearer of the footwear item causes movement of the moveable member thereof to cause: (i) conveyance of air, via the plurality of air flow channels and the further channels that perforate the under-foot layer, between the ball/toe region of the footwear item and the said portion of the under-foot layer that is remote from the ball/toe portion thereof ; and (ii) ingestion of air via the or each supply channel for conveyance via the plurality of air flow channels.

33. A footwear item according to Claim 26 or Claim 32 including a heel having a recess having received therein the gas pump.

34. A footwear item according to any of Claims 30 to 33 wherein the under-foot layer and the sole are releasably securable together to permit removal of the under-foot layer from the footwear item.

35. A footwear item according to Claim 34 including a pressure actuated seal between the under-foot layer and the insole, the said seal being actuatable by foot pressure acting on the under-foot member.

36. A footwear item according to Claim 35 wherein the pressure actuated seal includes one or more regions of a substantially gas impermeable, low tack adhesive material coated on the under-foot layer and/or the sole adjacent the in-use positions of the plurality of air channels and the supply channels so as to seal the sole about the said channels to permit conveyance

of air therein.

37. A footwear item according to Claim 36 wherein the coated adhesive is the result of a screen printing process.

38. A footwear item according to Claim 36 or Claim 37, wherein the adhesive is or includes a coagulated polyurethane resin or a coagulated latex ; and the under-foot layer is or includes blown polyurethane, ethyl vinyl acetate and/or polyethylene.

39. An under-foot layer generally as herein described, with reference to and/or as illustrated in the accompanying drawings.

40. A gas pump generally as herein described, with reference to and/or as illustrated in the accompanying drawings.

41. A footwear item generally as herein described, with reference to and/or as illustrated in the accompanying drawings.

42. Use of a septum valve to control the release of pressurised gas in a chamber forming part of a footwear item.