GB2385086A - Glass edge seal for double glazed unit - Google Patents

Abstract

A double glazed unit has two glass panes 1 held apart by a peripheral insulating spacer 3, preferably plastic, with the space 5 between the panes being evacuated. An additional seal 2 is provided on the unit edge to protect the spacer from the forces resulting from evacuation of the unit. Seal 2 is a glass strip fused, at reference 4, to each glass pane 1.

Description

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A Seal for an Evacuated Window This invention relates to an evacuated window.

Evacuated windows are windows that are thermally insulated. Its purpose being is to reduce the amount of heat loss though a window (Heat Transfer). Evacuated windows whose panes are made of glass, have two panes spaced a small distance apart and sealed around its edges then all the air in the space between the panes is taken out.

This then produces atmospheric pressure on both outer faces of the window which is very great, lKg per cm2. Therefore these seals have to be thick enough to be able to withstand this pressure.

One area that heat may travel through the unit is the seal. Glass seals in the evacuated windows have two purposes 1. To keep air out of the spaces (5).

2. To hold the panes apart.

Since other materials with lower heat transfer are available such as plastics, these can be used instead to hold the glass panes apart which would make it possible for the glass seal's width to be reduced. The spacer also directly supports the seal from forces exerted from direction B in Fig 1 due to atmospheric pressure. This seal/spacer construction would have less heat transfer through itself than just a single glass seal.

An evacuated window U. S patent no 4,393, 105 uses a metal seal around its perimeter and in between the glass panes to keep the air out. This however has two disadvantages.

1. The thermal conductivity of a metal is higher than that of glass.

2. The seal does not have a spacer on the inner side to support it from the force of atmospheric pressure from direction B in Fig 1. Therefore the seal relies on its own strength to withstand this. If it had support from the inner side then the width of the seal could be reduced which would then mean a reduction in thermal conductivity through the seal.

For an evacuated window unit to keep its thermal insulative effectiveness the space in between the glass panels would have to remain permanently evacuated i. e. permanently sealed.

There are other patents, which use a combination of two materials to reduce heat transfer through the seal/spacer construction but these let air seep through the seal/spacer construction over a period of time. This is mostly due to the fact that their seals are not fused to the panes but are stuck on some other way, for example glue, sealant.

One type of evacuated window applied for wo/0129357 uses seals and pillars around the periphery of the panes but the seal is not entirely flat as the seal (3) in Fig I. This results in a higher thermal conductivity through the seal.

The reason for this invention is to enable an evacuated glass window to have a low heat transfer as possible through its seal/spacer construction and to keep air out permanently without any air seepage.

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Description of the Invention According to the present Invention there is provided an evacuated glass window comprising of two glass panels, an insulated spacer around its perimeter edge in between the two panes and a glass seal around its outer perimeter edge.

Fig 1 is a side cross sectional view of the evacuated window unit according to the embodiment of this invention.

Fig 2 is a plan view of the evacuated unit according to the embodiment of this invention.

Fig 3 is the same as fig 1 except with the seal detached.

There is provided two glass transparent panes (1) which are parallel to each other and spaced a distance apart. A spacer (3) made of an insulative material, is placed up to the edge and in between the two panels. This spacer is rectangular and runs continually around the perimeter of the window panes.

A glass seal strip (2) is then placed around the perimeter edge of the panels, so that the glass strip (2) is up against and touching the spacer. Then the glass seal strip (2) and panes (1) are fused (4) together.

Using existing methods air is then pumped out of the space (5) in between the two panes either through the panes or the seal and the air outlet is then sealed.

The exterior surface (6) of the spacer which is touching the seal, is flat. The interior surface (7) of the seal is also flat. Since the complete surface area (6) is in contact with the surface (7) then the seal will receive full contact support from the spacer when the air in space (5) is pumped out resulting in a force of atmospheric pressure being exerted from direction B and onto the seal (2) in Fig 1.

Since the glass seal is completely thin and flat the seals thermal conductivity will be low compared to a seal which is thick or a seal which is shaped around many pillars as explained in page 1.

The spacer will be made of a material which can withstand the atmospheric pressures exerted on the window panes but also have a lower thermal conductivity then that of glass. A plastic is one material that can be used.

The glass seal strip (3) can be cut from a larger sheet of glass.

Existing methods are used to extract any moisture out of the said space (5).

Claims (1)

1. Claims 1. A glass seal strip which is thin and flat and it does not contribute to any structural strength to the evacuated window unit and has direct support from an insulative spacer is fused to the perimeter edge of the two glass panes.