GB1573203A - Temperature responsive device for opening a ventilator - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO A TEMPERAWRE-RESPONSIVE DEVICE FOR OPENING A VENTILATOR (71) We, DEREK THOMAS MURRAY RYNHART. of 38 Church Street, Appleby, Magma, Nr. Burton on Trent and STANLEY ARTHUR BLOXHAM. formerly of 97 Hazelwood Lane, London N 13, and now of Chesling, 209 Stanstead Road, Bishops Stortford, Hertfordshire both of British Nationality, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following statement:- The present invention relates to a device for opening a ventilator in response to a change in temperature.

According to the invention there is provided a device for opening a ventilator in response to a rise in temperature comprising a master piston and cylinder to contain hydraulic fluid, and a slave piston and cylinder, the slave piston being driven by said hydraulic fluid. and means to move said master piston comprising a combination of metal members of different coefficients of thermal expansion.

Conveniently the device may comprise a first tube, a second tube nested within the first tube. being secured to the first tube adjacent one end thereof, said slave piston being mounted in one part of said second tube and being adapted to open a ventilator. the other part Jf the second tube being secured to the master piston head mounted within a sealed master piston chamber defined by the first tube. the interior of the second tube being in communication with said master piston chamber and containing hydraulic fluid together with said master piston chamber, the coefficient of thermal expansion of the first tube being greater than the coefficient of thermal expansion of the second tube.

In order that the invention may be more readilv understood and so that further features thereof may be appreciated the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a perspective view from above of a plant enclosure provided with automatic ventilating means in accordance with the invention; Figure 2 is a perspective view from below of the plant enclosure of Figure 1 in a different position, and Figure 3 is a cross-sectional view of part of the central tube of the plant enclosure of Figures 1 and 2.

Whilst the invention relates primarily to means for opening a ventilator the invention will be described with reference to a plant enclosure which has such ventilator opening means.

Referring to Figures 1 and 2 a plant enclosure 1 comprises a circular base 2 with a peripheral upstanding side-wall 3, to form an open topped bowl shaped container. Provided in the lower part of the base are small apertures 4 each of which terminates in a respective recess 5.

An upwardly directed tubular projection 6 is provided in the centre of the base, which receives and engages an aluminiurn tube 7.

The tube 7 extends upwardly above the base for a considerable distance and mounted on the top of the tube 7 is a disc 8 formed of a transparent material which extends radially outwardly away from said tube. The radially outermost part of the disc 8 is deflected downwardly. The disc 8 may be formed of a plastics material and strengthening ribs may be provided. The disc 8 is provided with a central socket adapted to engage with the uppermost portion of the aluminium tube 7.

Provided adjacent the periphery of the disc 8 are six apertures 9, and rot proof suspension strings are on the said disc 8 by passing the strings through said apertures and knotting strings. The other end of each string may be passed through one of the apertures 4 provided in the base as hereinbefore described, and again the string may be knotted, the knot resting in the recess 5 formed in the lowermost surface of the base of the container. The strings provide rigidity for the described assembly.

Mounted on the aluminium tube 7 between the base and the disc are four separate bowl shaped containers 11 each formed of a moulded plastics material. Each container is in the form of a circular container having a circular base and an upstanding peripheral wall, there being a tubular projection 12 extending upwardly from the middle of the container which accommodates the aluminium tube 7. The bore through each container is a tapering bore and a resilient rubber ring is mounted on the aluminium tube at the position where each container is to be located, the rubber being engaged between the conical portion of the bore and the tube, thus supporting the container in position. It will be appreciated that any number of such containers may be provided, although it is envisaged that normally the maximum number of such containers will be five.

The base of each container 11 is not flat, but instead the bases slope downwardly in a radially inward direction. Thus each base has a slope corresponding to that of an inverted cone, the portion of the base adjacent the tube 7 being lower than the portion of the base adjacent the peripheral upstanding wall.

A round roof or support member 13 is movably mounted above said disc 8 and a cylindrical resilient plastics material sleeve 14 is supported by the outer periphery of the support member 13. The sleeve may be formed of high grade ultra-violet connective P.V.C. with a predetermined shading characteristic. The plastics material sleeve 14 extends substantially vertically downwardly from the outer periphery of the support member 13 towards the base 2. The lowermost edge of the sleeve 14 is scalloped, being provided with semicircular recesses 15 separated by rectangular fingers 16. The fingers 16 are provided with stop fasteners and each embrace a ring 18 which entirely surrounds the base 2. The ring 18 is formed of metal tube or the like and acts to weigh down the sleeve 14.A full length zip 19 is provided extending from a point adjacent the support member 13 to a point adjacent the base 2, the zip being openable to permit access to the interior of the plant enclosure. The lower edge of the sleeve between the fingers may, in an alternative embodiment, be cut away rectangularly, so that the lower edge of the housing has a castellated appearance.

The roof or support member 13 is moulded from a plastics material, which may be opaque, or which may be transparent or translucent. The support member 13 is of circular shape in plan, and is provided with a central circular upwardly projecting portion 20. Thus the support member 13 has a resemblance to a flat brimmed hat. Air vents 21 are formed in the side walls of the projecting portion 20, the vents being in the form of rectangular apertures covered by bird-proof netting or mesh. Recessed gutters 22 are formed in the uppermost surface of the upwardly projecting portion 20 to direct rain water or the like falling on the support member 30 away from the air vents 21.The diameter of the upwardly projecting portion 20 is substantially the same as that of the disc 8, and the inner surface of the lower part of the upwardly projecting portion 20 is shaped sealingly to engage with the downwardly deflected peripheral portion of disc 8.

Means are provided for raising the roof or support member 13 relative to the disc 8 when the temperature within the housing exceeds a predetermined level. As the roof or support member 13 is raised the scalloped portion of the plastics material sleeve 14 between the fingers 16 will rise above the level of the outwardly flared upper edge of the side wall 3 provided on the base 2, thus permitting ventilating air to flow into the lower region of the housing and to escape from the top of the housing. Thus the housing will be ventilated. The upper part of the side wall 3 is flared so that the side wall will sealingly engage the sleeve 14 before the support member 13 is raised.This prevents undesired ventilation of the housing, and also any consideration formed on the inner surface of the sleeve will meet the flared portion of the side wall when running down the sleeve, and will be returned to the container forming the base 1.

In the illustrated embodiment of the invention the aluminium tube is formed of two interconnected sections and mounted within the upper section of the aluminium tube 7 is a steel tube 23, the steel tube 23 being anchored to the aluminium tube 7 adjacent the uppermost portion of the aluminium tube 7, by means of a lock nut 24 engaging a threaded end portion of the tube 23 and retaining, via a washer 25, an aluminium bung 26 provided with an 0 ring 27 sealing against the inner surface of the tube 7 and a flange 28 engaging the end of tube 7. The lower end of the steel tube 23 passes through a central aperture in a movable sealing bung 29 which is mounted within the aluminium tube 7. The bung 29 is formed of nylon and is provided with sealing O-rings 30 engaging the inner surface of aluminium tube 7, and sealing O-rings 31 engaging the outer surface of steel tube 23. Secured to the lowermost end of the steel tube 23 by means of a set screw 32 and a sealing washer 33 which together seal the end of tube 23 is a nylon piston member 34 which is provided with sealing O-rings 35 which engage with the interior wall of the aluminium tube 7. An aperture 36 is formed within the steel tube adjacent the upper surface of the piston member 34.

Slidably mounted within the upper end of the steel tube 23 is a slave piston member 37 provided with sealing O-rings 38. The piston member 37 is secured to the roof or support member 13 by means of a lock nut 39 and washers 40. The interior surfaces of the steel tube 23 that engage the piston may be chrome plated.

A second aluminium tube 41 is provided which is coaxial with the steel tube 23 and which extends from the bung 26 to the upper surface of the movable bung 29, a nylon washer 42 being located between the end of the tube 41 and bung 29.

The space above the piston 34 and beneath the movable bung 29 within aluminium tube 7 and the interior of the steel tube 23 are filled with a hydraulic fluid, and the hydraulic fluid is preferably a fluid which has 9 great degree of thermal expansion, such as ethyl alcohol or isopropyl alcohol.

In operation of the device the plant enclosure would be assembled as shown in Figures 1 and 2, the two portions of tube 7 being connected together, the various containers 2, 11 being filled with a soil-less compost, peat or any other suitable growing medium. Seed or plants may then be sown in the various containers, and it is envisaged that plants such as tomatoes may be grown with their roots located in the base 2, the plants being supported by the suspension strings 10. and other plants such as lettuces, spring onions. radishes or the like (i.e. plants which do not grow to an excessive height) may be planted within the remaining containers 11 mounted on the aluminium tube 7.

The plants may be watered in the usual way.

It is envisaged that no drain apertures will be needed in the containers, although it will be appreciated that such drain apertures may be provided if necessary.

The roof or support member 13 and the sleeve 14 may be rotated as a whole, the piston member 37 merely rotating within the steel tube 23. Thus with the zip 19 in the open position and with one or more of the fingers 16 released from the ring 18 access may be gained to all the plants contained within the plant enclosure. Fasteners 43 are provided on sleeve 14 to which fingers 16 may be connected to facilitate access to the plant enclosure.

If the zip 18 is closed and the temptrature within the housing rises the aluminium tube 7 and the steel tube 23 will both expand, but the aluminium tube 7 will expand more than the steel tube 23 since aluminium has a higher coefficient of thermal expansion than steel. The base of the aluminium tube is fixed in position and thus the point of connection of the aluminium tube 7 and the steel tube 23 at the uppermost ends of those tubes will rise, and since the coefficient of the expansion of the steel tube 23 is less than to the coefficient of expansion of the aluminium tube 7 the piston head 34 contained within the aluminium tube 7 will also rise, from its initial position. However, the second aluminium tube 41 will also expand, this tube expanding by an amount corresponding to the expansion the adjacent portion of the outer tube 7.Thus, whilst the bung 29 engaged by the lower end 42 of the tube 41 will rise in response to the rise in temperature, it will not rise as much as does the point of connection of the aluminium tube 7 and steel tube 23, and bung 29 will rise much less than does piston head 34. Thus, the hydraulic fluid contained within the aluminium tube 7 between bung 29 and piston head 34 is compressed, as the distance between these components is reduced thus forcing compressed hydraulic fluid through hole 36 and up the steel tube 23. This hydraulic fluid will force the piston 37 contained in the top of the steel tube upwardly, thus driving the roof or support member 13 away from the disc 8 and thus effectively the ventilation apertures 21 provided at the top of the plant enclosure.

The active surface area of piston 37 is much less than the active surface area of piston 34 and so a mechanical advantage is obtained.

As the roof or support member rises further, as the result of a very high temperature the scalloped portions 15 of the sleeve 14 located between the fingers 16 will rise above the level of the base 2, thus permitting through flow ventilation of the housing.

It is envisaged that the hydraulic fluid may be a fluid such as ethyl alcohol which, in itself, has a high thermal coefficient of expansion, and the use of such a fluid will tend to reinforce the above described effect, thus causing the cruciform member to be moved away from the disc member by a considerable distance when the temperature rises.

When the temperature within the plant enclosure falls the hydraulic fluid will contract, and also the various steel and aluminium tubes described above will contract, returning the plant enclosure to its initial condition in which the roof or support is in a lowered position engaging sealingly the inner part of the portion 20 of the roof or support member, thus closing the air vents 21, and in which the scalloped portions of the tube 14 are below the rim of the container 2.

If the hydraulic fluid contracts by a large amount the movable bung 29 will move to accommodate such contraction, the bung 29 moving away from the end of the aluminium tube 41 and thus preventing the formation of a vacuum or partial vacuum over the hyd raulic fluid.

When the interior of the plant enclosure is cool there is no need for ventilation, and with all the air vents 21 closed, as described above, moisture will be conserved within the plant enclosure, as in a bottle garden. Moisture condensing on the interior of sleeve 14 will run down the sleeve, down the flared lip of bowl 2 and into the soil or peat. Moisture condensing on the under surfaces of containers 11 will run towards the central tube 7, because of the shape of the under surfaces of the containers, and will run down the tube into the next container. In this way the formation of large drops of water which may drip into a lower container damaging seedlings or the like is prevented.

As the temperature within the plant enclosure rises, so the ventilation provided is increased. Initially the air vents 21 are opened, and if this provides sufficient ventilation the actlon of the hydraulic device ceases.

However, if further ventilation is required, the action of the hydraulic device will continue until through flow ventilation is provided. The containers 11 or the tube 7 will then act as baffles, forming swirls of air as the ventilating air flows through the plant enclosure, thus ventilating all parts of the enclosure. As the temperature falls, so the ventilation will be reduced automatically.

It is to be understood that the invention also relates to the hydraulic temperature sensitive device described above, even when not used in a plant enclosure of the type described and illustrated. For example, a device of this type may be used in a conventional greenhouse.

Reference is made to co-pending Application No. 35835/75, (Serial No. 1 573 202) from which the present application is divided, and which relates to a plant enclosure having means for raising all or part of a housing relative to a base.

WHAT WE CLAIM IS: 1. A device for opening a ventilator in response to a rise in temperature comprising a master piston and cylinder to contain hydraulic fluid, and a slave piston and cylinder, the slave piston being driven by said hydraulic fluid. and means to move said master piston comprising a combination of metal members of different coefficients of thermal expansion.

2. A device according to claim 1 comprising a first tube, a second tube, nested within the said first tube, being secured to the first tube adjacent one end thereof, said slave piston being mounted in one part of said second tube and being adapted to open a ventilator, the other part of the second tube being secured to the master piston head mounted within a sealed master piston chamber defined by the first tube. the interior of the second tube being in communication with said master piston chamber and containing hydraulic fluid together with said master piston chamber, the coefficient of thermal expansion of the first tube being greater than the coefficient of thermal expansion of the second tube.

3. A device according to claim 1 wherein said master piston is within a cylinder formed by a first tube of metal of relatively high coefficient of thermal expansion and the slave piston is within a second tube of relatively low coefficient of thermal expansion, the two tubes being secured together at one end thereof, the master piston being secured to the first tube.

4. A device for operating a ventilator substantially as herein described with reference to and as illustrated in Figure 3 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. raulic fluid. When the interior of the plant enclosure is cool there is no need for ventilation, and with all the air vents 21 closed, as described above, moisture will be conserved within the plant enclosure, as in a bottle garden. Moisture condensing on the interior of sleeve 14 will run down the sleeve, down the flared lip of bowl 2 and into the soil or peat. Moisture condensing on the under surfaces of containers 11 will run towards the central tube 7, because of the shape of the under surfaces of the containers, and will run down the tube into the next container. In this way the formation of large drops of water which may drip into a lower container damaging seedlings or the like is prevented. As the temperature within the plant enclosure rises, so the ventilation provided is increased. Initially the air vents 21 are opened, and if this provides sufficient ventilation the actlon of the hydraulic device ceases. However, if further ventilation is required, the action of the hydraulic device will continue until through flow ventilation is provided. The containers 11 or the tube 7 will then act as baffles, forming swirls of air as the ventilating air flows through the plant enclosure, thus ventilating all parts of the enclosure. As the temperature falls, so the ventilation will be reduced automatically. It is to be understood that the invention also relates to the hydraulic temperature sensitive device described above, even when not used in a plant enclosure of the type described and illustrated. For example, a device of this type may be used in a conventional greenhouse. Reference is made to co-pending Application No. 35835/75, (Serial No. 1 573 202) from which the present application is divided, and which relates to a plant enclosure having means for raising all or part of a housing relative to a base. WHAT WE CLAIM IS:

1. A device for opening a ventilator in response to a rise in temperature comprising a master piston and cylinder to contain hydraulic fluid, and a slave piston and cylinder, the slave piston being driven by said hydraulic fluid. and means to move said master piston comprising a combination of metal members of different coefficients of thermal expansion.

2. A device according to claim 1 comprising a first tube, a second tube, nested within the said first tube, being secured to the first tube adjacent one end thereof, said slave piston being mounted in one part of said second tube and being adapted to open a ventilator, the other part of the second tube being secured to the master piston head mounted within a sealed master piston chamber defined by the first tube. the interior of the second tube being in communication with said master piston chamber and containing hydraulic fluid together with said master piston chamber, the coefficient of thermal expansion of the first tube being greater than the coefficient of thermal expansion of the second tube.

3. A device according to claim 1 wherein said master piston is within a cylinder formed by a first tube of metal of relatively high coefficient of thermal expansion and the slave piston is within a second tube of relatively low coefficient of thermal expansion, the two tubes being secured together at one end thereof, the master piston being secured to the first tube.

4. A device for operating a ventilator substantially as herein described with reference to and as illustrated in Figure 3 of the accompanying drawings.