GB2168787A - Improvements in or relating to valve actuators - Google Patents

Abstract

An actuator for a valve member in a housing including a non-circular outer surface 20 has an adaptor 55 with a bore conforming in part to the surface 20. A releasable bayonet connection 60, 57 connects the adaptor to a holder for a non-circular socket 52 cooperable with a non-circular valve-operating element 19. A releasable clamp 70, 74, 75 holds the adaptor to the housing and prevents engagement of the bayonet connection until the clamp is engaged. The holder is connected through a drive connection including universal couplings to a pneumatic actuator for rotating the valve member. The valve may be used to supply uranium hexafluoride to containers. <IMAGE>

Description

SPECIFICATION Improvements in or relating to valve actuators This invention relates to valve actuators and in particular to actuators for valves comprising a housing, a valve member in the housing movable to control fluid flow between an inlet to the housing and an outlet from the housing, the housing including an outer surface which is non-circular in section.

According to this invention an actuator for a valve as referred to above comprises a collar for engaging said outer surface and means operably connectable to the valve member for moving the valve member.

The valve member may be rotatable and connected to an operating element having a non-circular outer surface, said means being cooperable with said element outer surface.

Said means may comprise a socket having a non-circular bore for receiving said operating element.

The socket may be biassed by spring means towards the operating element.

The socket may be mounted in a ring member releasably connected to the collar. A spring-loaded plunger may releasably lock the ring member and the collar.

There may be a clamp for embracing the valve housing and releasably holding the collar to the valve housing.

The socket may be operatively connected to a universal coupling on a shaft having a splined telescopic connection with another shaft connected by another universal coupling to an actuator for rotating the socket.

The actuator may be a pneumatic actuator.

The invention may be performed in various ways and one specific embodiment with possible modifications will now be described by way of example with reference to the accompanying drawings, in which: Figure I is a side view of a valve operating apparatus; Figure 2 shows part of a control panel; Figure 3 is a pneumatic circuit; and Figure 4 is side view part in section on an enlarged scale of part of the apparatus of Figure 1; and Figure 5 is a perspective exploded view of a valve collar with part removed.

The valve operating apparatus 10 is shown as used to operate a filling valve 11 for a cylinder 12 (only part shown) of uranium hexafluoride, but the apparatus can be used to operate other valves controlling fluid flow.

The cylinder 12 rests on stillage 13 on a weigh scale 14 with an indicator enabling a user to know when the cylinder has been filled to a desired extent. The cylinder 12 has an annuiar projecting rim 15 surrounding the valve 11. The valve 11 includes an inlet stem 16 threaded into the top 17 of the cylinder 12 and communicating with a supply stem 18 which is adapted to be connected to a source of liquid. A valve member (not shown) inside the valve 11 controis liquid flow between the supply stem 18 and the inlet stem 16. The valve member is connected to an operating element 19 which can be rotated to open and close the valve. The valve housing of valve 11 includes a square section portion 20, and threaded stem 22. A hexagonal gland nut 21 engages stem 22. Gland nut 21 compresses gland seals to seal on the valve operating element and the cylindrical bore of housing 11.The protruding end of operating element 19 is of non-circular section.

The valve operating apparatus 16 includes a pneumatically operated valve actuator including a pneumatic motor 24 arranged to rotate a bush 25 fixed to a rotatable horizontal output shaft 26. The actuator 23 is secured to support framework 27 and is supplied with air under pressure from a suitable source via line 28. If desired the output shaft 26 can be rotated by a hand wheel 30. An indicator 31 is arranged to rotate with shaft 26 to provide an indication of the position of the valve member in the valve 11.

In the present case the actuator 23 is arranged to operate the valve 11 through a manipulator arm 32.

The shaft 26 is secured to a bracket 33 forming part of a universal joint 34 fixed to a hollow shaft 35 in splined telescopic engagement with a shaft 36 connected to another universal joint 37 an output part 38 of which is operatively connected to an end member 39 of a valve collar device 40. The parts 35, 36 form a splined expansion coupling.

The end member 39 has a radial pin 41 connecting the end member in a tubular part 42 with a radial flange 43 abutting a flanged ring of bearing 44 received in an axial end aperture in outer housing 45 which is secured in a ring 46. The tubular part 42 is retained in housing 45 by a thrust washer and circlip 42a. A rod 47 has a square section portion 48, received in a square-section aperture in end 49 of tubular part 42, and a round section part 50 welded to one end of a socket 51 which has a bore 52 of which the part further from the end 39 has a section corresponding to that of the valve operating member 19 for receipt thereof. Thus rotation of the actuator output shaft 26 will rotate the valve operating member 19 and thus move the valve member between open and closed positions. A helical spring 9 extends between flange 43 and flange 8 on socket 51.

The valve 11 may have, for example, a spindle which requires about eight revolutions to move from the valve fully closed position to the valve fully open position and this may produce an axial movement of the end 19 of about an inch. This movement is accommodated by section 48 of rod 47, which is connected to socket 51 which engages element 19, being allowed to slide in the squaresection aperture in end 49 of tubular part 42.

The housing 45 has a bayonet-type releasable connection with an adaptor 55. Location Pin 56 prevents incorrect assembly of the unit, and has a larger diameter than the cross section of groove 57 in portion 58. The adaptor 55 has an end portion 58 having a circular section bore, and a shank portion 59 has a square section bore corresponding to the periphery of square section portion 20. The adaptor 55 is generally open on one side for receipt of the valve 11 (see Figure 4).

A spring loaded plunger 60 has an inner end which can move in the groove 57 and be received in an aperture 61 in the end portion 58 for releasably locking the adaptor 55 to the housing 45.

Plunger 60 is released by a 90 degree rotation of knob 60a secured to plunger 60. This raises the plunger relative to its base housing enabling the plunger to move in slot 57 to enable separation of the parts.

When Plunger 60 engages apertures 61 a Vee form on the underside of the knob engages a Vee form in the housing, allowing the plunger to lower.

An arm 70 is pivoted at 71 in adaptor 55. The arm 70 can be swung to embrace the stem 16 and the free end 72 of the arm 70 displaces a spring loaded plunger 73 from the end of slidable rod 74 carrying an operating knob 74a, the rod then enters an aperture 75 in the arm 70 to lock the adaptor to the valve 11. There are thus means which ensure that the bolt 74 can only be placed in an engaged position when the arm 70 is in position to engage the bolt. Also, the engagement of plunger 60 of housing 45 with the aperture 61 of adaptor 55 when the housing and adaptor are connected is only possible when the knob 74a (and thus bolt 74) is in the engaged position.

The spring 9 keeps the socket 51 in engagement with the valve operating member 19 which is cylindrical with the outer end portion of square crosssection.

The use of splined shafts and universal joints gives adequate degrees of freedom to the drive to allow for normal variation in cylinder and valve positions with respect to the actuator and to facilitate coupling.

Figure 3 shows an operating circuit for the actuator 23. The circuit includes pressure air supply 100, isolation valve 101, a filter 104, a lubricator 105, a pressure regulator (reducer) 106 with pressure gauge, lights 107(1Y and 107(11) showing green when mains supply is on, and an isolator circuit 108. An outlet 109 is connected to inputs 109a and an output 110 from the lubricator 105 is connected at 110a to a valve 111 The slide valves in circuit portion 112 are spool valves. A knob 113 can be manually operated to supply air to energise the actuator to turn the actuator shaft 26 to move the valve member towards the open position. A knob 114 can be manually operated to energize the actuator to turn the actuator shaft 26 to move the valve member towards a closed position.Light 113a is illuminated amber when following operation of knob 113 a timer in the opening circuit switches a spool-valve (allowing for valve opening) that results in isolation of the common air supply to the opening circuit. The air being connected to the closing circuit; similarly light 114a is illuminated amber when following operation of knob 114 a timer 143a in the closing circuit switches a spool valve (allowing for valve closure) that results in isolation of the common air supply to the closing circuit, the air being connected to the opening circuit. An emergency signal at input 115 will return the valve 11 to closed position at any time. When the emergency signal is present, light 115a is illuminated red. Manual knob 116 can be operated to reset the actuator under the control of knobs 113, 114 when the emergency signal is removed.

Thus, the air supply 100 to the control panel passes through an isolation valve 101 and filter 104. A regulator with pressure gauge 106 allows the operating pressure to be set, hence the operating torque from the air motor 24, of actuator 23. A relief valve 103 prevents overpressurisation in the event of failure of regulator 106.

Isolation valve 108 operates two valves each having a visual indicator. One valve 102a isolates the control circuit air 109. The other valve 102b isolates the lubricated actuator air 110 from lubricator 105. When the control panel 112 is powered, visual indicators 107(1) and 107(11) show green.

When necessary handwheel 30 is rotated until the valve position indicator (pressure gauge 31) shows the valve to be in the closed position. The valve collar is then attached to the filling valve 11, the valve member being in the closed position.

When valve 113 is operated, control circuit air 109a from valve 146 switches valve 140 allowing air 109a to: a. Activate timer 143 (to limit duration of air to opening port of actuator).

b. Switch shuttle valve 142 which then switches 111 (Supplies lubricated air to valve 141).

c. Switch valve 141 to connect lubricated air 110a with opening port of actuator 23.

d. Switch valve 147, removing the air supply 109a and providing- an exhaust for visual indicator 114a.

When the pre-set time to which the timer has been set has lapsed (allowing for the valve opening operation), timer 143 switches valve 144 allowing air 109a to: a. Operate visual indicator 113a to show amber.

b. Switch shuttle valve 145 which then switches valve 140 (cancelling the opening operation).

c. Switch valve 146 to connect supply air 109a to valve 114 (closing valve) and to exhaust supply pipe from 146 to 113.

The closing circuit operation is similar to the opening circuit.

Emergency closure This circuit ensures closure of the valve irrespective of the mode of operation.

Valve 148 isolates the control panel from an emergency signal 115 when the control panel is isolated.

An emergency signal 115 to the control panel or operation of valve 115b switches valve 116 allowing air 109a to: a. Operate visual indicator 115a to show red b. Switch shuttle valve 145 which switches valve 140 (overriding any on line opening operation).

c. Pass through the exhaust port of valve 149 to operate the closing circuit.

In the event of an emergency during the closing operation the closure will continue as normal.

When valve 149 switches, instead of exhausting the air supply to the closure circuit, air from the emergency closure valve 116 is connected to the closure circuit.

Air will be supplied to the actuator maintaining the closing torque until the emergency signal has been removed (115 and/or 115b) followed by operation of the reset button 116.

A torque limit for operating element 19 is determined by the working pressure of the system. The torque developed by the actuator varies dependent on which cam is contacted by the air motor. There are two cams (higher and normal running torque) for each mode of operation. Changing the mode of operation results in the cams passing beneath the air motor. The high torque cam passes momentarily beneath the air motor to give a higher torque (+ 50 .Ó) to overcome any resistance to unseating.

The air motor comes to its normal running position beneath a cam that gives the normal running torque.

A relief valve is incorporated into the circuit to ensure that the motor is not subjected to excessive pressures.

Operation of the signal 115 could be electrically in response to an alarm signal from a sensor.

If the pneumatic supply fails, the hand wheel 30 is used to close the valve 11.

Some cylinders have convex ends and some concave ends. This means that the operating member can point either upwards or downwards. The collar can be orientated accordingly.

When the valve is opened the gland nut 21 can unscrew, particularly if the valve stem is bent and rubs on the gland nut. The extent to which the gland nut 21 can unscrew is determined by the clearance between the gland nut 21 and locking ring 46, which restricts further movement. To ensure that filling valve 11 is not unscrewed from the cylinder 12 during the valve opening operation an arm 120 Figure 1 sliding in a swivel 120a is releasably clamped at one end 121 to the rim 15 and at the other end is connected to a swivel 122 Figure 5 on the valve collar.

In modified arrangements the following may be present: 1. means enabling the air pressure signal to the pressure indicator 31 to interlock with other steps in the filling procedure.

2. means which prevent energizing of the actuator 23 until the clamp 121 is engaged and until the pin 60 is locked. The sytem would be improved if a. it detected the engagement of a valve by adaptor 55.

b. the sensor for locking pin 60 is fitted to adaptor 55 to ensure that the pin is locked down with the valve collar connected.

To ensure connection of the clamp 121 with the valve collar a sensor would need to be fitted to swivel 122.

The actuator may be such as to give an (adjustable) higher torque when moving from closed or open position; the period of application of the higher torque being adjustable. On commencement of both the opening and closing operations the actuator momentarily applies a higher torque (+ 50%) to overcome any resistance to the unseating. The ratio of the increase is fixed, resulting from the air motor plunger contacting a cam as the actuator mechanism changes operating mode.

The mechanism on changeover of operating mode results in a high torque cam swinging into engagement with the air motor plunger (giving the increased torque), and then swinging out of en engagement when a normal running torque cam is engaged.

If the circuit were to be modified, the higher torque could be obtained by applying an increased pressure to the air motor for an adjustable time period. The increased air pressure would need to be applied when the actuator mechanism had change over to avoid the increased torque being itself boosted by 50% through contact of the air motor piston with the high torque cam.

3. Means enabling the pressure pulses in the air supply line to the air motor 24 (resulting from operation of the motor) to be counted to ensure valve displacement from the seated position.

Claims (12)

1. An actuator for a valve as hereinbefore referred to, said actuator comprising an adaptor for engaging said outer surface, and means operably connectable to the valve member for moving the valve member.

2. An actuator as claimed in claim 1, for a valve in which the valve member is rotatable and is connected to an operating element having a non-circular outer surface, in which said means is cooperable with the operating element outer surface.

3. An actuator as claimed in claim 2, in which said means comprises a socket having a non-circular bore for receiving said operating element.

4. An actuator as claimed in any preceding claim, in which the socket is operatively connected to a universal coupling on a shaft having a splined telescopic connection with another shaft connected by another universal coupling to an actuator for rotating the socket.

5. An actuator as claimed in claim 4, in which the actuator is pneumatic actuator.

6. An actuator as claimed in any of claims 3 to 5, in which the socket is biased towards said adaptor.

7. An actuator as claimed in any of claims 3 to 6, in which the socket is mounted in a ring member and means for releasably connecting the adaptor to the ring member.

8. An actuator as claimed in claim 7 and claim 6, including a spring-loaded plunger for releasable locking the ring member and the adaptor.

9. An actuator as claimed in any preceding claim, comprising means for releasably clamping the adaptor to the valve housing.

10. An actuator as claimed in claim 9, said clamping means comprising a clamp element pivoted at one end to the adaptor, said housing being receivable between the clamp element and the adaptor, and means for releasably connecting the adaptor and the other end of the clamp element.

11. An actuator as claimed in claim 9 or claim 10 when appendant to claim 7 or claim 8, including means for preventing releasable connection of the ring member and the adaptor unless the adaptor is clamped to the housing bysaid releasable clamp ing means.

12. An actuator for a valve substantially as hereinbefore described with reference to and as shown in Figure 5 of the accompanying drawings.