GB2217451A

GB2217451A - Shape memory metal actuator

Info

Publication number: GB2217451A
Application number: GB8907450A
Authority: GB
Inventors: William John Craske
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-04-08
Filing date: 1989-04-03
Publication date: 1989-10-25
Also published as: GB8907450D0

Abstract

Temperature responsive control apparatus (2) comprises a first part (4), a second part (6), and a memory metal torsion spring (8) for moving the first and the second parts (4, 6) relatively to one to one another in dependence upon changes of temperature. A basing spring (64) opposing spring (8) reduces hysteresis. Another spring may be used to assist spring (8). The apparatus is used to operate ventilators, louvres, flap valves and windows in buildings, greenhouses and air conditioning systems. If the ventilator or window is locked the spring (8) may be disconnected from one of the parts to prevent overstressing. <IMAGE>

Description

TEMPERATURE RESPONSIVE CONTROL APPARATUS This invention relates to temperature responsive control apparatus.

Temperature responsive control apparatus is well known. For example, temperature responsive control apparatus is known for automatically operating ventilators to regulate temperature conditions in structures such for example as greenhouses, conservatories, horticultural buildings and inhabited buildings. The known temperature responsive control apparatus usually operates by pivoting a hinged roof panel between various open and closed positions in dependence upon changes of environmental temperature such for example as ambient air temperature.

The hinged roof panel is often made of glass. The hinged roof panel or other ventilation arrangement is usually such that it is relatively heavy and thus the temperature responsive control apparatus needs to exert substantial force in order to open the hinged roof panel or other structure. Typically, a force of 12-16 Kgm may be required to move an edge opening panel with a movement of the order of 200 mm. The known temperature responsive control apparatus is advantageous in that it removes the need for constant attention to the temperature in a structure provided with the temperature responsive control apparatus.

The temperature responsive control apparatus can operate automatically to open a ventilation structure when the temperature rises above a chosen level, and automatically to close the ventilation structure when the temperature falls below the chosen level. The known temperature responsive control apparatus does however suffer from the disadvantage that it is bulky and/or complicated and/or expensive to produce. This is due mainly to the relatively large mechanical force required to open and close the ventilation structure, and also to the fact that the variations in ambient temperature practically experienced are small so that the obtained movements often have to be amplified by means of levers and linkages in order to obtain the required degree of movement of the ventilation structure.Furthermore, the known temperature responsive control apparatus is often prone to early failure when in service.

It is an aim of the present invention to provide temperature control apparatus which obviates or reduces the above mentioned problems.

Accordingly, this invention provides temperature responsive control apparatus comprising a first part, a second part, and a memory metal torsion spring for moving the first and the second parts relatively to one another in dependence upon changes of temperature.

The temperature responsive control apparatus may be one in which the first and the second parts are pivotably connected together.

If desired, the temperature responsive control apparatus may be one in which the first part is a movable part, and in which the second part is a fixed part. Alternatively, the temperature responsive control apparatus may be one in which the first part is a movable part, and in which the second part is movable part.

When the first and the second parts are both movable parts, then the first and the second parts may be arms which are adapted for pivotal connection to parts of a structure to be provided with the temperature responsive control apparatus.

The memory metal torsion spring may comprise a coiled body portion and a pair of end members which extend from the coiled body portion, the end members being for securing one to each of the first and the second parts.

The end members may be provided with attachment means for securing the end members one to each of the first and the second parts. Alternatively, the end members may be plain and they may be for fitting in recessed portions of the first and the second parts.

The memory metal torsion spring may be made of a heat treated brass alloy. Other metals may however be employed.

If desired, the temperature responsive control apparatus may-include an auxiliary spring for controlling the operation of the memory metal torsion spring.

In one embodiment of the invention, the auxiliary spring acts to oppose the operation of the memory metal torsion spring, thereby to act as a biasing spring to reduce hysteresis in the position taken up by the memory metal spring as the temperature fluctuates up and down.

When the auxiliary spring acts as a biasing spring, the auxiliary spring may be a torsion spring.

Other types of spring may however be employed.

In another embodiment of the invention, the auxiliary spring acts to assist the operation of the memory metal torsion spring, thereby to act as an assistance spring which assists the memory metal torsion spring in moving the first and the second parts relatively to each other. With such an auxiliary spring, the force required to lift a roof vent or other ventilation structure can be split in to two components.

One component is constant whilst the other component increases as the roof vent or other similarly operating ventilating structure moves towards the horizontal position. The assistance spring can control the constant component so that this constant component can be removed from the effort required by the memory metal torsion spring. This means that the size of the memory metal torsion spring can be considerably reduced over what would be required if the auxiliary spring were not present.

When the auxiliary spring is acting as an assistance spring, then the auxiliary spring may be a strip spring.

Other types of spring such for example as leaf springs may be employed.

The present invention also provides a structure when provided with the temperature responsive control apparatus.

The structure may be a greenhouse, a conservatory, a cold frame, or another type of horticultural building.

The structure may also be a home, office or a factory.

Other types of structure may also be provided with the temperature responsive control apparatus.

Embodiments of the invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 is a perspective view of first temerature responsive control apparatus, and shows additionally a hinge device; Figure 2 is a side view of the temperature responsive control apparatus shown in Figure 1; Figure 3 is a top plan view, partially cut away, of the temperature responsive control apparatus shown in Figure 1; Figure 4 is a side view similar to that shown in Figure 2 but shows the temperature responsive control apparatus moved from the closed position shown in Figure 2 to an open position; Figure 5 is a perspective view of second temperature responsive control apparatus; Figure 6 is a perspective view of third temperature responsive control apparatus; Figure 7 is a side view of fourth temperature responsive control apparatus; ; Figure 8 shows the temperature responsive control apparatus of Figure 7 in use and in a closed position; Figure 9 shows the temperature responsive control apparatus of Figure 7 in use and in an open position; and Figure 10 is an exploded view of the temperature responsive control apparatus shown in Figure 7.

Referring to Figures 1 to 4, there is shown temperature responsive control apparatus 2 comprising a first part 4 and a second part 6. The apparatus 2 further comprises a memory metal torsion spring 8 for moving the first part 4 and the second part 6 relatively to one another in dependence upon changes of temperature.

The first and the second parts 4, 6 are pivotally connected together by a pivot pin 10. The first part 4 is a movable part and it is provided with a pair of lugs 12, 14 which define a space 16 for receiving a sheet of glass (not shown). The opposite side of the sheet of glass fits in a space 18 defined by a pair of lugs 20, 22 on a hinge 24o The hinge 24 has a movable part formed by the lugs 20, 22 and a fixed part 26. The fixed part 26 has apertures 28 by means of which the hinge 24 is secured to a fixed part of a structure such for example as a frame. The second part 6 is similarly provided with apertures 30 for securing the second part 6 to the fixed structure.

The spring 8 comprises a coiled body portion 32 and two end members 34, 36 which extend from the body portion 32. The end members 34, 36 are for securing one to each of the first and the second parts 4, 6 respectively. More specifically, the end member 34 is provided with attachment means 38 which connects to the first part 4 by a pivot pin 40. The end member 36 is provided with a similar attachment means 42 which connects to the second part 6 by a pivot pin 44.

The apparatus 2 further comprises an arm 46 which is pivotally secured to the second part 6 by means of a pivot pin 48. The arm 46 is provided with a stud 50 which projects through to a slot 52 in the second part 6. The stud 50 and the slot 52 enable the arm 46 to be rotated through a small angular segment with respect to the second part 6. A screw threaded member in the form of a locking nut 54 can be tightened to secure the arm 46 in any chosen angular position. The second part 6 is provided with position marks 56, whilst the arm 46 is provided with an indicator arrow 58.

The apparatus 2 further comprises an auxiliary spring 60 which acts to oppose the operation of the spring 8, thereby to act as a biasing spring which acts to reduce hysteresis in the position taken up by the spring 8 as the temperature fluctuates up and down.

As can be seen, the spring 60 is a torsion spring and it has a body part 64 and end members 66, 68. The end member 66 hooks into a chosen one of three apertures 70 in the attachment means 38. The end member 68 hooks into a chosen one of three apertures 72 in the attachment means 42.

The spring 60 is a spring steel torsion spring which is wound to act in the opposite torsional direction to the spring 8. The spring 8 is a memory metal torsion spring which is made of a metal alloy.

The spring 8 is manufactured in such a way that its end members 34, 36 close together as the spring 8 is warmed. In the free condition of the spring 8, movement may commence at a typical temperature of 100C, with the end members 34, 36 becoming parallel at approximately 35 C. Figure 2 illustrates the closed position of the apparatus 2, and Figure 4 illustrates the open position of the apparatus 4. It will be seen from a comparison of Figures 2 and 4 that the spring 8 has caused the first part 4 to rotate through substantially 900 about the pivot pin 40, to a position in which the lugs 12, 14 and therefore the sheet of glass held between the lugs 12, 14 is in a substantially horizonal position. This horizontal position would normally correspond to the fully open position of a panel being controlled, for example in a roof.

If required calibration of the temperature at which the spring 8 operates can be effected by loosening the locking nut 54 and rotating the arm 46 through a small angle about the pivot pin 48. The locking nut 54 is then retightened. This adjustment is able to give a recalibration over a narrow calibration band.

Referring now to Figure 5, there is shown second temperature responsive control apparatus 2. Similar parts as in Figure 1 to 4 have been given the same reference numerals for ease of comparison and understanding and their precise construction and operation will not again be given.

In Figure 5, a sheet of glass 74 is shown positioned in the space 16. A sheet member 76 which may be made of wood, glass, metal or another material is shown positioned in a space 78 formed between a pair of lugs 80, 82. The sheet member 76 is a fixed sheet member and the apparatus 2 operates to open and close the sheet of glass 74 with respect to the sheet member. 76. In the embodiment shown in Figure 5, the spring 8 operates in a reverse mode to that in Figure 1 so that in Figure 5, the spring 8 opens when it is heated. As can be seen, the apparatus 2 is mounted between the centre of the pivoted edge of the moving sheet of glass 74 and the sheet member 76 immediately above the sheet of glass 74.

In Figure 5, the spring 60 may act in one of two ways. In a first way, the spring 60 may act in the same way as the auxiliary spring 60 described above with reference to Figures 1 to 4. In the second way, the spring 60 may act as an auxiliary spring which assists the operation of the spring 8, the spring 60 thereby acting as an assistance spring for assisting the spring 8 in moving the first and the second parts relatively to each other. The use of an auxiliary spring as an assistance spring will be described in more detail herein below with reference to Figure 7 to 10.

Figure 5 also shows how the lugs 12, 14; 80,82 are provided with apertures 84 by means of which screws, nuts and bolts or rivets as appropriate are employed to secure the sheet of glass 74 and the sheet member 76 in position.

Referring now to Figure 6, similar parts as in Figures 1 to 4 have again been given the same reference numerals for ease of comparison and understanding.

The form of the apparatus 2 shown in Figure 6 is similar to that shown in Figures 1 to 4. The apparatus 2 shown in Figure 6 is designed to be secured between the centre of the pivoted edge of the moving sheet of glass 74 and the fixed sheet member 76S which is positioned below the sheet of glass 74. The apparatus 2 shown in Figure 6 is especially useful where there is very little room available above the moving sheet of glass 74.

Referring now to Figures 7 to 10, there is shown fourth temperature responsive control apparatus 2 and again similar parts as in Figures 1 to 4 have been given the same reference numerals for ease of comparison and understanding.

In Figures 7 to 10, it will be seen that both the first part 4 and the second part 6 are movable parts.

The part 4 is secured by a bracket 86 to a roof panel 88.

The bracket 86 is pivotally connected to the first part 4 by a pivot pin 90. The second part 6 is connected by a cranked arm 92 to the inside of a roof structure 94.

The second part 6 is pivotally connected to the cranked arm 92 by a pivot pin 96. The roof panel 88 opens and shuts about hinges, one of which is shown as hinge 98.

Figure 10 shows most clearly how the pivot pin 10 operates in conjunction with and extends through a pair of stub members 100, 102. The stub members 100, 102 extend inside and rotate inside a drum 104. The drum 104 is secured to the second part 6 by screws ( not shown) passing through apertures 106 in the second part 6 and into screw threaded apertures 108 in the drum 104. As shown, the pivot pin 10 has a groove 110 which extends beyond the far side of the first part 4 as shown in Figure 10 and which receives the illustrated collet 112.

The end members 34, 36 of the spring 8 are plain as hoqn. The body portion 32 of the spring 8 fits inside the drum 104 such that the end member 34 locates in a groove 114 formed in an inner face 116 of the first part 4. A slot 115 is provided in the drum 104 to enable assembly to be achieved.

The end member 36 locates in a recessed part 118 formed in an inner face of the second part 6.

The apparatus 2 shown in Figures 7 to 10 is such that the auxiliary spring 60 acts to assist the spring 8, thereby to act as an assistance spring which assists the spring 8 in moving the roof panel 88 to the open position. More specifically, the spring 8 is a memory metal torsion spring which has been heat treated so that it unwinds when the temperature rises above a chosen value. The spring 8 rewinds again when the temperature falls. The angular movement of the end members 34,36 of the spring 8 are arranged to be made equal to the required angular movement of the roof panel 88. The spring 60 is formed from a single strip of metal as shown and it acts as a constant torque spring. Both springs combine to open the roof panel 88. The spring 60 is used to remove some of the load from the spring 8 so that the spring 8 can be made to be smaller and cheaper.The spring 60 is fixed to the drum 104 which forms a torque drum at point 120 shown in Figure 7, the fixing being effected by a screw 122. One end 124 of the spring 60 is curled as shown and it locates around a torque reaction pin 126 which extends from the inner face 116 of the first part 4. The spring 60 acts such that it attempts to roll itself up around the pin 126 and, in so doing, applies an opening torque to the first part 4. Without additional assistance from the spring 8, the roof panel 88 remains just positively closed under the influence of the spring 60.

During the operation of the apparatus 2 shown in Figures 7 to 10, the spring 8 unwinds as the ambient temperature rises above a predetermined level, for example 150C. As stated above, the end member 34 is fixed in position in the groove 114. The end member 36 is freely located in the recessed part 118 as can be seen from Figure 7. As the temperature rises, the end member 36 moves away from the end member 34, so that the end member 36 moves downwardly as shown in Figure 7.

The end member 36 eventually contacts a screw 128 which is located in the second part 6. As the end member 36 bears on the screw 128, the spring 8 is able to add its opening effort to the effort provided by the spring 60, thereby to lift the roof panel 88.

The screw 128 can be adjusted so that it screws into or out of the recessed part 118. This adjustment alters the temperature at which the roof panel 88 actually starts to openS since the adjustment controls the amount of movement needed by the end member 36 before it contacts the inner end of the groove 1280 The various types of apparatus 2 shown in the drawings are of relatively simple construction so that they can easily and cheaply be produced. The simple construction also facilitates a good working life of the various illustrated types of apparatus 2.

It is to be appreciated that the embodiments of the invention described above with reference to the accompanying drawings have been given by way of example only and that modifications may be effected. Thuss for example, the various roof structures may be made of lightweight material such as plastics materials. The apparatus 2 can also be used for ventilation structures in walls or other positions. Thus, for example, the apparatus 2 may be used to open ventilating louvres, or for opening and closing flap valves in air conditioning systems. Where auxiliary springs 60 are employed as assistance springs, these may be omitted where the part of the structure to be opened is sufficiently light.Where it is desired to employ an auxiliary spring as an assistance spring, then it is not necessary to employ the spring 60 shown in the drawings and cheaper tension or compression springs may be employed. Where adjustment of the operating temperature range of the apparatus 2 is required, then adjustment means other than the locking nut 54 or the screw 128 may be employed. The memory metal torsion spring may also be referred to as a shaped memory effect spring. If the ventilation arrangement is locked in a closed position and the temperature rises, this may adversely affect the operation of the memory metal torsion spring. In order to prevent this happening, the apparatus 2 or the structure in which the apparatus 2 is fitted may be provided with a release mechanism such for example as a release handle. Usually the apparatus 2 will be provided with the release mechanism so that the apparatus 2 is in a released non-functional condition until such time as it is required for operation. In the released nonfunctional condition, the memory metal torsion spring can open and close as it desires without coming up against fixed resistance which might alter its memory characteristics so that, for example, the memory spring might not open as far next time were it not for the presence of the release mechanism. The spring 60 may comprise a plurality of strips of metal.

Claims

1. Temperature responsive control apparatus comprising a first part, a second part, and a memory metal torsion spring for moving the first and the second parts relatively to one another in dependence upon changes of temperature.

2. Temperature responsive control apparatus according to claim 1 in which the first and the second parts are pivotally connected together.

3. Temperature responsive control apparatus according to claim 1 or claim 2 in which the first part is a movable part, and in which the second part is a fixed part.

4. Temperature responsive control apparatus according to claim 1 or claim 2 in which the first part is a movable part, and in which the second part is a movable part.

5. Temperature responsive control apparatus according to claim 4 in which the first and the second parts are arms which are adapted for pivotal connection to parts of a structure to be provided with the temperature responsive control apparatus.

6. Temperature responsive control apparatus according to any one of the preceding claims in which the memory metal torsion spring comprises a coiled body portion and a pair of end members which extend from the coiled body portion, the end members being for securing one to each of the first and the second parts.

7. Temperature responsive control apparatus according to claim 6 in which the end members are provided with attachment means for securing the end members one to each of the first and the second parts.

6. Temperature responsive control apparatus according to claim 5 in which the end members are plain and they are for fitting in recessed portions of the first and the second parts.

7. Temperature responsive control apparatus according to any one of the preceding claims in which the memory metal torsion spring is made of a heat treated metal alloy.

8. Temperature responsive control apparatus according to any one of the preceding claims and including an auxiliary spring for controlling the operation of the memory metal torsion spring.

9ç Temperature responsive control apparatus according to claim 8 in which the auxiliary spring acts to oppose the operation of the memory metal torsion spring, thereby to act as a biasing spring which reduces hysteresis in the position taken up by the memory metal torsion spring.

10. Temperature responsive control apparatus according to claim 9 in which the auxiliary spring is a torsion spring.

11. Temperature responsive control apparatus according to claim 8 in which the auxiliary spring acts to assist the operation of the memory metal torsion spring, thereby to act as an assistance spring which assists the memory metal torsion spring in moving the first and the second parts relatively to each other.

12. Temperature responsive control apparatus according to claim 11 in which the auxiliary spring is a strip spring.

13. Temperature responsive control apparatus substantially as herein described with reference to the accompanying drawings.

14. A structure when provided with the temperature responsive control apparatus as claimed in any -one of the preceding claims.

15. A structure according to claim 14 and which is in the form of a greenhouse, a conservatory, a cold frame, a home, an office or a factory.