GB2130686A - A temperature responsive trigger mechanism for valve actuator - Google Patents

Abstract

The temperature responsive trigger mechanism (for the valve actuator) has a first part 16 forming pivot bosses and adapted to be mounted on a base member (e.g. cover member 3 of the actuator), a second part 17 formed as a latch plate and pivotal relative to said first part, and a temperature responsive member 18 which is adapted to displace said second part, on attaining an elevated temperature. The second part is adapted to be releasably coupled to a member (e.g. a lever 13 of an actuator mechanism) which is to be released at a predetermined temperature. The actuator itself has a housing with a rotary actuator member therein biased between first and second positions corresponding to the latched state and the released state of the trigger mechanism. The displacement of the second trigger mechanism part 17 allows a lever 13 to free engaging, associated abutments 6,7, thereby causing the rotary actuator member to be biased to its second position. <IMAGE>

Description

SPECIFICATION A temperature responsive trigger mechanism for a valve actuator This invention relates to a temperature responsive trigger mechanism for a valve actuator and a temperature responsive valve actuator.

Such valve actuators are employed to actuate rotary mechanisms such as rotary valves, for example, in the event of a fire. The mode of actuation may be to open or close a line or duct depending on the requirements of the system. For example in the event of fire, it may either be desirable to close a duct in order to prevent fire spreading along the duct, e.g. in the case of a ventilator duct, or it may be desirable to open a valve in a fluid line for the purpose of dumping fluid so as to reduce a supply of flammable fluid when there is a danger of the fire reaching that supply, e.g. a valve in an oil or petroleum fuel line.

Sometimes such valves and their valve actuators have been termed "fire safe" or "fire-proof valves" but this terminology may be misleading, hence the designation herein "temperature responsive valve actuator" in relation to the present invention.

Prior art patent specification no. 635,256 relates to an improved fire-proof valve for 9entilating ducts. A plate which acts as a duct closure member is eccentrically mounted on a spindle within the duct. A helical spring is connected at opposite ends to the spindle and to the duct to urge the plate into its duct closing position. A crank at one end of the spindle is connected to one end of a fusible link, which link has its other end connected to the duct. The fusible link normally holds the crank and thereby the spindle with the plate in the "duct open" position against the bias of the spring. In the event of a fire, the fusible link will be destroyed freeing the crank and allowing the spindle to turn under the bias of the spring whereby the plate closes the duct.

It is an object of the present invention to provide a temperature responsive trigger mechanism for a valve actuator which is selfcontained and separate from any valve and which may be supplied for fitting to existing fluid passage systems including rotary valves.

It is an object of this invention to provide a temperature responsive trigger mechanism for a valve actuator which may be tested nondestructively which may be actuated manually and which may be reset on repeated occasions.

It is a further object of the present invention to provide an actuator which may be readily customised for a wide range of rotary mechanisms such as rotary valves.

According to one aspect of the invention there is provided a temperature responsive trigger mechanism comprising a first part adapted to be mounted on a base member, a second part associated with said first part and displaceable relative thereto, and a temperature responsive member disposed in operative relation to the second part, said second part being adapted to be coupled to a member which is to be released by said mechanism at a predetermined temperature.

In a preferred embodiment, the second part of the trigger mechanism comprises a latch plate which is pivotally mounted relative to the first part of the trigger mechanism and is adapted to engage with a said member which is to be released by said mechanism at a predetermined temperature. The first part may comprise means providing pivot bosses for at least one pivot about which one end of the latch plate is pivotally mounted. One of the second part and the member to be released may have a latch pin thereon which is adapted to engage with an aperture defined by the respective other one of said second part and said member to be released. A tension spring means may be associated with the second part of the trigger mechanism and arranged to prevent unintended release of the said second part of the trigger mechanism.

Cam means may be provided on said base member, said cam means being adapted to limit the degree of movement of said member (to be released) after triggering of the trigger mechanism.

Advantageously, the temperature responsive member is a coil having shape memory characteristics whereby the coil extends to release the second part of the trigger mechanism when the coil attains a predetermined temperature and whereby the coil returns to its original condition after cooling.

According to another aspect of the present invention there is provided a temperature responsive valve actuator comprising a cylindrical housing having cylindrical wall means together with an upper cover member and a lower cover member, a rotary actuator member located within the cylindrical housing and being rotatable between first and second limit positions which in use, define positions of the rotary valve, a spindle extending through said cover members of the cylindrical housing and being keyed to said rotary actuator member, biasing means located within said cylindrical housing and arranged to bias said rotary actuator from its first limit position towards its second limit position, lever means mounted on the upper cover member and operable to be rotatable with respect thereto, a first abutment means associated with said lever means, a second abutment means associated with the rotary actuator member, the first and second abutments being so adapted to operate that, with the rotary actuator member in its first position and said lever means constrained to prevent rotation thereof, the rotary actuator member is maintained in said first limit position against the bias of said biasing means and rotation of said rotary actuator member is prevented, a temperature responsive trigger mechanism including a first part mounted on said upper cover member, a second part associated with said first part and displaceable relative thereto, and a temperature responsive member disposed in operative relation to the second part, said second part being releasably coupled to said lever means, wherein said temperature responsive member is operative to cause said second part of said trigger mechanism to release said lever means at a predetermined temperature, the release of said lever means permitting rotation thereof and displacement of said first abutment means therewith so as to effect clearance of the first abutment means relative to the second abutment means, said clearance of the second abutment means enabling said rotary actuator member to be displaced under the bias of said biasing means to its second limit position.

It will be appreciated that the first and second limit positions of the rotary actuator member, in use, may correspond respectively to either "open" or "closed" positions of the rotary valve according to whether the valve is normally "open" or normally "closed" i.e. as to whether the rotary valve has an isolating role or a dumping role in the event of fire. The lower end of the spindle will be adapted for connection to the spindle of a rotary valve and the upper end of the spindle will be adapted for manual actuation of the actuator, for example, by having a configuration adapted to receive a complementary recess in a handle.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a sectional elevation, taken through the line A-A of Figure 2a, of a temperature responsive valve actuator according to the present invention; Figure 2a and 2b shows plan views of the actuator of Figure 1 in its first and second limit positions respectively; Figure 3 shows an elevation view of a temperature responsive trigger mechanism according to the invention suitable for use with the valve actuator of Figure 1; and Figure 4 shows in plan view the temperature responsive trigger mechanism of Figure 3.

In Figures 1 and 2 there is shown a temperature responsive valve actuator comprising a cylindrical housing 1 having cylindrical wall means 2 together with an upper cover member 3 and a lower cover member 4. The cover members 3, 4 are shown as separate members connected to wall means 2 by fastenings, e.g. at 29. A rotary actuator member 5 is located within the cylindrical housing 1 and is rotatable between first and second limit positions (to be described) which, in use, define positions of a rotary valve (not shown). A spindle 8 extends through the cover members 3, 4 of the cylindrical housing 1 and is keyed at 9 to said rotary actuator member 5.

Biasing means, in the form of a pre-stressed torsion spring 10, are located within the cylindrical housing 1. Spring 10 is arranged to bias the rotary actuator member 5 from its first limit position towards its second limit position. One end 11 of the spring 10 is connected with the lower cover member 4. The other end 12 of the spring 10 is connected with the rotary actuator member 5.

Lever means 13 is mounted on the upper cover member 3 and is operable to be rotatable with respect thereto. A first abutment means 6 is associated with said lever means 1 3. A second abutment means 7 (see Figures 1 and 2a) is associated with the rotary actuator member 5. The first and second abutments 6, 7 are so adapted to operate that, with the rotary actuator member 5 in its first position and the lever means 1 3 constrained to prevent rotation thereof, the rotary actuator member 5 is maintained in said first limit position against the bias of the spring 10 whereby rotation of said rotary actuator member is prevented; thus the first limit position corresponds to the position in which the abutment means 7 is in contact with a cam surface 6a of abutment means 6.A temperature responsive trigger mechanism 14 includes a first part 1 6 mounted on said upper cover member 3, a second part 17 associated with said first part 1 6 and displaceable relative thereto, and a temperature responsive member 18 disposed in operative relation to the second part 1 7. The second part 1 7 is releasably coupled to the lever means 13. The temperature responsive member 1 8 is operative to cause said second part 1 7 of said trigger mechanism 14 to release the lever means 13 at a predetermined temperature.

The release of the lever means 13 permits rotation thereof and displacement of said first abutment means 6 therewith so as to effect clearance of the first abutment means 6 relative to the second abutment means 7. Upon this clearance of the second abutment means 7, the rotary actuator member 5 is displaced under the bias of the spring 10 to its second limit position (Figure 2b). In the second limit position, the abutment means 7 contacts a limit stop 1 5 defined by a downward extension of the cover member 3 (Figure 2b).

The first abutment means 6 is coupled with the lever means 13 by means of a spindle 19, to which spindle 1 9 both the lever means 13 and abutment means 6 are keyed for rotation therewith: abutments means 6 being within the housing 1 and lever means 1 3 being above the cover member 3. In the position of the lever means 13 and abutment means 6 shown in Figure 1 ,the abutment means 6 is abutted by the abutment means 7 and movement of the abutment means 7, and thereby the rotary actuator member 5, is prevented.

Rotation of the lever means 13 about the axis of the spindle 1 9 also rotates the abutment means 6 taking the abutment means 6 out of the path of the abutment means 7 thus achieving clearance of the abutment means 6 relative to the abutment means 7: abutment means 6 is eccentric with respect to spindle 19, hence the interference with abutment means 7 in one rotary position thereof and clearance in another.

It is important that means be provided to prevent the lever 13 being reset independently of the rotary actuator member 5. Located on the upper surface of the rotary actuator member 5 is a further abutment member 33 which is arranged to abut a cam surface 6b of abutment 6 when the lever 13 has been released and the actuator 5 (and lever 13) is in the second limit position shown in Fig. 2b. The abutment member 33 prevents rotation of the abutment member 6 and hence the lever 1 3 in a direction towards its first position wherein the lever 1 3 is engaged by the part 17 of the trigger mechanism 14.In the absence of such a member 33 the lever 13 could be reset independently of the rotary actuator member 5 and this at least could give an erroneous indication of the state of the valve actuator and could give rise to a dangerous operational state. Because of the abutment member 33 the lever 13 can only be reset by rotation of the spindle 8 which thus rotates the actuator 5 and lever 13 together. Thus the position of lever 1 7 is always indicative of the operational position of the actuator 5.

The spindle 8 is adapted at 30 to receive a recessed hand tool for manual actuation thereof and is adapted at 31 for connection to the spindle of a rotary valve (not shown).

In order to describe the temperature responsive trigger mechanism 14 in greater detail, reference is now made to Figures 3 and 4 in which like numerals denote their counterparts in Figures 1 and 2. Thus, this mechanism comprises a first part 1 6 which is mounted on a base member 20 (which in the embodiments of Figures 1 and 2 is the cover member 3). A second part 1 7 is associated with the first part 1 6 and is displaceable relative thereto. A temperature responsive member 1 8 is disposed in operative relation to the second part 1 7. The second part 1 7 is adapted by means of an aperture 21 therein to be coupled to a member, namely pin 22 on lever means 13.Lever means 13 is to be released by the mechanism 14 at a predetermined temperature.

More specifically, the member 1 7 is a latch plate which is mounted on pivot pins 23 themselves journalled in spaced apart members (pivot bosses) which make up part of the first part 1 6. The latch plate 1 7 is thus pivotably mounted with respect to the pivot pins 23 and thereby capable of displacement such that, with the end 24 of the latch plate 1 7 raised, the pin 22 is released from the aperture 21 in the latch plate 17. The latch plate 1 7 has a tension spring 25 associated therewith: spring 25 extends between a bar 26 and a part 27 of the latch plate 1 7. The purpose of tension spring 25 is to ensure that a holding force is applied to the latch plate 1 7 thereby preventing unintended release of the latch plate 17, for example, due to vibration.

On the upper surface of the base member 20 (in Figure 1, the cover member 3), a cam surface (not shown) may be disposed below the lever means 13. This cam surface may have an arcuate extent of, for example, 900, and may have a gradual incline such that it prevents further travel of the lever means 1 3 about the axis of the spindle 1 9 after 900 of rotation. This prevents the lever means 13 travelling further than is necessary for the operation of the valve actuator 1.

In this embodiment, the temperature responsive member 1 8 is a helical coil actuator having "shape memory characteristics", such as supplied by, for example, Delta Metals Limited.

Such a coil actuator has the characteristics that it extends with a known force at a predetermined elevated temperature and that it will return to its original condition when its temperature returns to a "normal" temperature (e.g. normal ambient temperature). When the coil actuator 1 8 extends due to an increase in ambient temperature, it causes the latch member 1 7 to pivot about the pivot pins 23 and thereby release the pin 22 and thereby the lever means 1 3.

It will be noted from Figures 3 and 4 that the latch plate is configured with the downwardly extending extension 27, and that the spring 25 is adapted at either end with a hook-like end to be attached to the extension 27 and the bar 26. It should also be noted that the base member 20 (or cover member 3) has a stud or the like 32 which locates the temperature responsive member 1 8 in position relative thereto.

The temperature responsive member 1 8 in the form of a helical coil having "shape memory characteristics" is constituted from a metallic composition which has metallurgical properties such that (within the design specification of the mechanism) it will operate and return to its original configuration an unlimited number of times. It will be appreciated that the temperature to which the trigger mechanism 14 is responsive to trigger the part 1 7 (i.e. the latch plate) and release the associated member (in this case the lever means 13) may be selected according to design requirements simply by selecting a coil 1 8 which is adapted to extend and thereby release the latch plate 1 7 at that temperature.

It is advantageous that stop means, for example a metal strip, is arranged above the latch plate 1 7 for limiting the upward extent of its travel. For example, a strip (not shown) may be arranged between the members which make up the part 16: these members are in effect pivot bosses for the pivot pins 23. It will be noted that fastenings 28 secure the parts 1 6 to the base member 20. The advantage of providing the stop means to limit the travel of the latch plate 1 7 is that the temperature responsive member 1 8 is thereby prevented from leaving its location defined by stud 32.

The temperature responsive trigger mechanism 14 described above is a completely mechanical device which may be operated by remote control e.g. with a cable attached to the latch plate 1 7. In addition this mechanism 14 may be operated and latched manually for maintenance checks. Further the mechanism 1 4 may be non-destructively tested by suitably raising the ambient temperature without damage to the mechanism. The mechanism 14 can thus be supplied as a separate, self-contained, stored-energy mechanism which does not require or rely on other means, such as hydraulic, pneumatic, electrical or other means for its operation.

In operation, the valve actuator 1 is set as shown in Figure 1. On the ambient temperature rising to the operating temperature (or alternatively triggering by remote cable), the latch plate 1 7 lifts off the pin 22 (whether due to the expansion of temperature responsive member 1 8 or the pull of a cable). Lever means 13 is no longer constrained against rotation. The bias of spring 10 on rotary actuator 5 causes the abutment means 7 to force the abutment means 6 to rotate (and therewith lever means 13). Rotation or displacement of abutment means 6 leaves the path of abutment means 7 clear. This clearance enables the rotary actuator member 5 to rotate to its second position under the influence of biasing means (spring) 1 0. When it reaches the second limit position, the abutment means 7 abuts limit stop 15.Resetting may be effected by placing a hand tool on the end 30 of spindle 8 and rotating same in the sense to return abutment means 7 to its original position.

The abutment means 33 rotates with the actuator 5 thus allowing the lever means 1 3 to be returned to a position in which the pin 22 is in register with the aperture 21 in the latch plate 1 7.

The end 24 of the latch plate 1 7 is then pivotally returned by pivoting about pivot pins 23 to move downwardly such that the pin 22 engages in the aperture 21. In a modification, the cover member 3 may be rotatable with the spindle 8 whereby, as the spindle 8 is returned by rotation, the cam means (not shown) automatically returns the lever means 13.

Thus there has been described an actuator which is readily pre-tested prior to delivery and sealed and can be arranged to define limit positions for a rotary valve to be fitted thereto.

Furthermore, as the actuator spindle is biased by pre-stressed torsion spring means, different customer requirements in terms of the torque required by different rotary valve applications, can be met by selection from a range of pre-stressed torsion spring means and the selected torsion spring means may be incorporated in an otherwise standard actuator, thereby affording the manufacturing economy of tooling for a standard actuator, instead of a plurality, for different applications.

Likewise, a standardised actuator may be fitted, according to customer requirements, with a temperature responsive trigger mechanism selected from a range of temperature responsive mechanisms each responsive to different temperatures.

The actuator with its trigger mechanism is a self-contained, stored-energy device which does not require or rely on other means, such as hydraulic, pneumatic or electrical means for its operation.

Claims (12)

1. A temperature responsive trigger mechanism comprising a first part adapted to be mounted on a base member, a second part associated with said first part and displaceable relative thereto, and a temperature responsive member disposed in operative relation to the second part, said second part being adapted to be coupled to a member which is to be released by said mechanism at a predetermined temperature.

2. A trigger mechanism as claimed in Claim 1, wherein the second part of the trigger mechanism comprises a latch plate which is pivotally mounted relative to the first part of the trigger mechanism and is adapted to engage with a said member which is to be released by said mechanism at a predetermined temperature.

3. A trigger mechanism as claimed in either Claim 1 or Claim 2, wherein the first part comprises means providing pivot bosses for at least one pivot about which one end of the latch plate is pivotally mounted.

4. A trigger mechanism as claimed in any one of Claims 1 to 3, wherein one of the second part and the member to be released has a latch pin thereon which is adapted to engage with an aperture defined by the respective other one of said second part and said member to be released.

5. A trigger mechanism as claimed in any one of Claims 1 to 4, further comprising tension spring means associated with the second part of the trigger mechanism and arranged to prevent unintended release of the said second part of the trigger mechanism.

6. A trigger mechanism as claimed in any one of Claims 1 to 5, wherein the temperature responsive member is a helical coil actuator having shape memory characteristics whereby the coil extends to release the second part of the trigger mechanism when the coil attains a predetermined temperature and whereby the coil returns to its original condition after cooling.

7. A trigger mechanism as claimed in any one of Claims 1 to 6, further comprising cam means on said base member, said cam means being adapted to limit the degree of movement of said member (to be released) after triggering of the trigger mechanism.

8. A temperature responsive trigger mechanism arranged, constructed and adapted to operate substantially as hereinbefore described with reference to Figures 3 and 4 of the accompanying drawings.

9. A trigger mechanism according to any one of Claims 1 to 8 in combination with a valve actuator including a rotary actuator member located in a housing and rotatable between first and second limit positions, which, in use, define positions of a rotary valve, biasing means arranged to bias the rotary actuator member from its first limit position towards its second limit position, the trigger mechanism having its first part mounted on the housing and the member to be released being a lever means mounted on the housing and operable, on release, to be rotatable with respect thereto, the arrangement further comprising a first abutment means associated with said lever means, a second abutment means associated with the rotary actuator member, the first and second abutment means being so adapted to operate that, with the rotary actuator member in its first position and said lever means constrained to prevent rotation thereof, the rotary actuator member is maintained in said first limit position against the bias of said biasing means and rotation of said rotary actuator member is prevented and wherein said temperature responsive member is operative to cause said second part of said trigger mechanism to release said lever means at a predetermined temperature, the release of said lever means permitting rotation thereof and displacement of said first abutment means therewith so as to effect clearance of the first abutment means relative to the second abutment means, said clearance of the second abutment means enabling said rotary actuator member to be displaced under the bias of said biasing means to its second limit position.

10. A combination according to Claim 9, further comprising a third abutment means associated with said rotary actuator member and arranged to co-operate with said first abutment means to prevent rotation of said lever means to be recoupled with said second part independently of a corresponding rotation of said rotary actuator member to its first position.

11. A temperature responsive valve actuator comprising a cylindrical housing having cylindrical wall means together with an upper cover member and a lower cover member, a rotary actuator member located within the cylindrical housing and being rotatable between first and second limit positions which, in use, define positions of a rotary valve, a spindle extending through said cover members of the cylindrical housing and being keyed to said rotary actuator member, biasing means located within said cylindrical housing and arranged to bias said rotary actuator member from its first limit position towards its second limit position, lever means mounted on the upper cover member and operable to be rotatable with respect thereto, a first abutment means associated with said lever means, a second abutment means associated with the rotary actuator member, the first and second abutments being so adapted to operate that, with the rotary actuator member in its first position and said lever means constrained to prevent rotation thereof, the rotary actuator member is maintained in said first limit position against the bias of said biasing means and rotation of said rotary actuator member is prevented, a temperature responsive trigger mechanism including a first part mounted on said upper cover member, a second part associated with said first part and displaceable relative thereto, and a temperature responsive member disposed in operative relation to the second part, said second part being releasably coupled to said lever means, wherein said temperature responsive member is operative to cause said second part of said trigger mechanism to release said lever means at a predetermined temperature, the release of said lever means permitting rotation thereof and displacement of said first abutment means therewith so as to effect clearance of the first abutment means relative to the second abutment means, said clearance of the second abutment means enabling said rotary actuator member to be displaced under the bias of said biasing means to its second limit position.

12. A temperature responsive valve actuator as claimed in Claim 11, including a trigger mechanism as claimed in any one of Claims 1 to 9.

1 3. A temperature responsive valve actuator arranged, constructed and adapted to operate substantially as hereinbefore described with reference to Figures 1 to 4 of the accompanying drawings.

1 4. A temperature responsive valve actuator in combination with a trigger mechanism substantially as hereinbefore described with reference to and as illustrated in Figures 3 and 4.