CA1113280A - Transmission assembly for powered and manual operation - Google Patents
Transmission assembly for powered and manual operationInfo
- Publication number
- CA1113280A CA1113280A CA325,073A CA325073A CA1113280A CA 1113280 A CA1113280 A CA 1113280A CA 325073 A CA325073 A CA 325073A CA 1113280 A CA1113280 A CA 1113280A
- Authority
- CA
- Canada
- Prior art keywords
- worm
- transmission assembly
- sun gear
- planet gear
- teeth
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000005540 biological transmission Effects 0.000 title claims abstract description 32
- 230000033001 locomotion Effects 0.000 claims abstract description 10
- 230000002093 peripheral effect Effects 0.000 claims 2
- 238000001514 detection method Methods 0.000 claims 1
- 238000005096 rolling process Methods 0.000 description 3
- 238000001311 chemical methods and process Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K31/00—Actuating devices; Operating means; Releasing devices
- F16K31/02—Actuating devices; Operating means; Releasing devices electric; magnetic
- F16K31/04—Actuating devices; Operating means; Releasing devices electric; magnetic using a motor
- F16K31/05—Actuating devices; Operating means; Releasing devices electric; magnetic using a motor specially adapted for operating hand-operated valves or for combined motor and hand operation
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Retarders (AREA)
- Gear Transmission (AREA)
- Control Of Velocity Or Acceleration (AREA)
- Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
- Transmission Devices (AREA)
- Mechanically-Actuated Valves (AREA)
Abstract
ABSTRACT
A transmission assembly has a power input member and a power output member interconnected by an epicyclic gear train incorporating at least one sun gear element rotatable about its axis. A worm splined on a driving shaft is resiliently held in a datum position against axial movement from the datum position, and meshes with teeth provided on the periphery of the sun gear element. A detecting device is operable when the worm moves axially on the driving shaft from its datum position by a predetermined amount to detect such movement. The detecting device may incorporate an electric switch connected into the control circuit of an electric motor operatively connected to the power input member.
A transmission assembly has a power input member and a power output member interconnected by an epicyclic gear train incorporating at least one sun gear element rotatable about its axis. A worm splined on a driving shaft is resiliently held in a datum position against axial movement from the datum position, and meshes with teeth provided on the periphery of the sun gear element. A detecting device is operable when the worm moves axially on the driving shaft from its datum position by a predetermined amount to detect such movement. The detecting device may incorporate an electric switch connected into the control circuit of an electric motor operatively connected to the power input member.
Description
~13280 A ~RANSMISSION ASSEMB~Y FOR POWERED AND
MANUA~ OPE~A~ION
__ ___ _____ __ The invention relates to a transmission assembly for powered and manual operation alternatively.
This assembly is especially intended for use in a valve actuator.
It is common practice to provide valves (for example those used in the pipework of chemical process plants) with powered valve actuators, usually driven by electric motors. However, for safety reasons it iæ necessary for the valve actuator to be operable manually should the motor which normally drives it fail, as for example when it~ electric motor suffers a power cut. Previously known valve actuators capable of powered and manual operation suffer from the serious disadvantage that, should the power supply to a valve be unexpeotedly restored after a power failure and whilst an operative is attempting to move the valve manually, the part of the actuator which the operative - is holding may turn rapidly with possible serious ~ consequencea ~or the operative. It is thus very J~ ~ desirable to provide a transmission as~embly which l~ does not suffer from this disadvantage.
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The invention seeks to provide such a ~ transmission assembly.
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MANUA~ OPE~A~ION
__ ___ _____ __ The invention relates to a transmission assembly for powered and manual operation alternatively.
This assembly is especially intended for use in a valve actuator.
It is common practice to provide valves (for example those used in the pipework of chemical process plants) with powered valve actuators, usually driven by electric motors. However, for safety reasons it iæ necessary for the valve actuator to be operable manually should the motor which normally drives it fail, as for example when it~ electric motor suffers a power cut. Previously known valve actuators capable of powered and manual operation suffer from the serious disadvantage that, should the power supply to a valve be unexpeotedly restored after a power failure and whilst an operative is attempting to move the valve manually, the part of the actuator which the operative - is holding may turn rapidly with possible serious ~ consequencea ~or the operative. It is thus very J~ ~ desirable to provide a transmission as~embly which l~ does not suffer from this disadvantage.
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The invention seeks to provide such a ~ transmission assembly.
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-2-A transmission assembly according to the invention includes a power input member and a power output member interconnected by an epicyclic gear train incorporating at least one sun gear element rotatable about its axis, a worm splined on a driving shaft and resiliently held in a datum position against axial movement from the datum position, said worm meshing with teeth provided on the periphery of the sun gear element,and a detecting device operable when the worm :; moves axially on the driving shaft from its datum position by a predetermined amount to detect such movement.
~ he transmission assembly may include an : electric motor operatively connected to the power input member, the detecting device incorporating an electric switch connected into the control circuit of the electric motor.
:~ The worm may be provided at one end with an ~- ex~ension formed with a circumferential groove, the ~ : detecting means incorporating a pin engaging the groove.
.~ The transmission assembly may incorporate two rotatable sun gear elements coaxial with one another ~: and formed with different numbers of teeth and a planet ~ : gear having two coaxial gear elements fixed to one .~` another and arranged to perform an orbital moti~n .'`: .
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~3Z~) around the sun gear element with each planet gear element in mesh with a respective sun gear element, the power input shaft being coupled to the planet gear so as to be capable o~ imparting said orbital motion to the planet gear, one of said sun gear elements being that in meshing engagement with the worm and the other sun gear element being connected to the power output member.
- Spring means may be provided on the driving shaft to encircle the driving shaft and press against at least one end of the worm ~hereby to urge the worm to the datum position.
'' ~he spring means may be arranged to press against ;;l both ends of the worm so that they act in opposition to hold the worm resiliently ln its datum poeition. -The spring means may be formed of at ~east one stack of Belleville washers.
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.. ~ ~ ' The power output member may be formed with an extension arranged to act as a support for the planet gear,and for the sun gear element meshing with the worm, said sun gear element and planet gear being mounted on the power output member extension by bearing means.
he power input member may carry a balance ... . . .
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weight arranged in diametral line with the axis of the planet gear and at the opposite side of the axis of the power input member from the axis of the planet gear.
~ he sun gear elements may be both in the form of rings formed with internal teeth, the sun gear element meshing with the worm being also formed with external teeth meshing ~ith the worm, the planet gear being located within the rings and mes~ng with the internal teeth and the balance weight being also located within the rings to occupy a part of the crescent shaped space defined by the portion of the periphery of the planet gear not in mesh with the sun gear elements and the portion of the periphery of the sun gear elements n~ engaged with the planet gear.
The extension of the power output member may be connected to a tell-tale pointer indicating the angular position of the power output member.
A practical embodiment of the invention as applied to a-valve actuator is illustrated in the accompanying drawings, although it will be understood that the assembly has other applications In the , drawings ~ig. 1 is a section through a transmission assembly of the invention and its associated motor, Fig. 2 is a section along the line 2-2 in Fig. ; and Fig. 3 is a diagram of the epicyclic gear of Fig. 1 as if viewed through the line 3-3 in Fig. 1 ' ' ~ " . ' ~ .
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The transmission assembly shown in the : ,~
accompanying drawings comprises a housing (generally designated 1) having upper and lower sections 2, and
~ he transmission assembly may include an : electric motor operatively connected to the power input member, the detecting device incorporating an electric switch connected into the control circuit of the electric motor.
:~ The worm may be provided at one end with an ~- ex~ension formed with a circumferential groove, the ~ : detecting means incorporating a pin engaging the groove.
.~ The transmission assembly may incorporate two rotatable sun gear elements coaxial with one another ~: and formed with different numbers of teeth and a planet ~ : gear having two coaxial gear elements fixed to one .~` another and arranged to perform an orbital moti~n .'`: .
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~3Z~) around the sun gear element with each planet gear element in mesh with a respective sun gear element, the power input shaft being coupled to the planet gear so as to be capable o~ imparting said orbital motion to the planet gear, one of said sun gear elements being that in meshing engagement with the worm and the other sun gear element being connected to the power output member.
- Spring means may be provided on the driving shaft to encircle the driving shaft and press against at least one end of the worm ~hereby to urge the worm to the datum position.
'' ~he spring means may be arranged to press against ;;l both ends of the worm so that they act in opposition to hold the worm resiliently ln its datum poeition. -The spring means may be formed of at ~east one stack of Belleville washers.
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.. ~ ~ ' The power output member may be formed with an extension arranged to act as a support for the planet gear,and for the sun gear element meshing with the worm, said sun gear element and planet gear being mounted on the power output member extension by bearing means.
he power input member may carry a balance ... . . .
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weight arranged in diametral line with the axis of the planet gear and at the opposite side of the axis of the power input member from the axis of the planet gear.
~ he sun gear elements may be both in the form of rings formed with internal teeth, the sun gear element meshing with the worm being also formed with external teeth meshing ~ith the worm, the planet gear being located within the rings and mes~ng with the internal teeth and the balance weight being also located within the rings to occupy a part of the crescent shaped space defined by the portion of the periphery of the planet gear not in mesh with the sun gear elements and the portion of the periphery of the sun gear elements n~ engaged with the planet gear.
The extension of the power output member may be connected to a tell-tale pointer indicating the angular position of the power output member.
A practical embodiment of the invention as applied to a-valve actuator is illustrated in the accompanying drawings, although it will be understood that the assembly has other applications In the , drawings ~ig. 1 is a section through a transmission assembly of the invention and its associated motor, Fig. 2 is a section along the line 2-2 in Fig. ; and Fig. 3 is a diagram of the epicyclic gear of Fig. 1 as if viewed through the line 3-3 in Fig. 1 ' ' ~ " . ' ~ .
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The transmission assembly shown in the : ,~
accompanying drawings comprises a housing (generally designated 1) having upper and lower sections 2, and
3 respectively which are fixed together by means of bolts (not shown). Within the upper section 2 of the housing is secured an electric motor 4 which can rotate a cog 5. This cog 5 meshes with an input gear wheel 6 ~, of the transmission assembly, the point of engagement of these two members thus forming the torque input point ;~
of the transmission assembly.
The input gear wheel 6 is rotatable about the ~
axis of a shaft 7 which extends through a central .:
aperture in the gear wheel 6. A sleeve member 8 , . .
,;l encircles the shaft 7~ being held in position by a ,.-' shoulder 9 thereon. Ball races are provided on the ~ '~
.,. ~ radially-outward surfaoe of the~sleeve member 8 and on .''~
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the radia11y-1nward~ surface of a balanoe weight member 10 which enoircles the sleeve member 8. A plurality of balls ll held between the ball races on the sleeve member 8 and the balance weight member :10 render the latter rotatable relative to the shaft 7 about the axis thereof~ -and slnce the 1nput gear wheel 6 is fixed to the balance weight member 8Iby a,bolt 12, the input gear wheel 6 is thus rendered rotat O le about the axis of the shaft 7.
: The balance weight member 10 comprises three ~ ~ 3 sections, namely an annular section lOa, which abuts and is fixed to the gear wheel 6, a crescent-shaped balance weight lOb which depends downwardly from one side of the annular section lOa, and a hollow cylindrical section lOc, which also depends downwardly from the annular section lOa; all three sections are integral with one another. ~he outside diameter of the cylindrical section lOc is off-set from the axis of the shaft 7 and within the cylindrical section lOc a bore of the cylindrical section lOc is concentric with the shaft 7. Wibl~nthe bore of the cylindrical section lOc is located a roller bearing assembly 14 in position around the lower part of the shaft 7, thus ensuring free rotation of the cylindrical section lOc about the shaft 7.
~ he radially-outward æurface of the cylindrical section lOc is provided with a ball race, and a plurality of balls 15 are held between this ball race and a further ball race provided on the radially-inward surface of a planet gear wheel 16, which is thus rendered freely rotatable about the cylindrical aection lOc. ~he radially-outward surface of the planet gear wheel 16 bears two sets of straight-cut teeth, namely an upper set 17 comprising fifty-six teeth and a lower set 18 .~ . .
comprising fifty-five teeth. As best see in ~ig. 1 the pitch diameter of the upper set of teeth 17 is ~ .
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slightly greater than that of the lower set 18.
~ he upper set of teeth 17 are meshed with straight-cut teeth 19 on the radially-inward surface of an annular member 20 whose axis coincides with that of the shaft 7. As shown in Fig. 3, because the pitch diameter of the teeth 17 is approximately 85% of the pitch diameter of the teeth 19, about eight teeth in each set are always meshed with the other set. This reduces the load on the teeth in mesh, enabling straight-cut rather than helical teeth to be used and also permitting the use of narrower teeth than would have been possible had only one or two teeth in each set been meshed with the other set.
The lower set of teeth 18 on the planet gear wheel are meshed with teeth on the radially inward surface of a sun gear 21 which is integral with and centered on the shaft 7. The pitch diameter of the teeth 18 is about 85~o of the pitch diameter of the teeth on the sun gear 21 so that about eight teeth .
of each set are always in mesh with the teeth of the ~ other set, with the resultant advantages discussed ;'~ above with reference to the teeth 17 and 19.
Since the planet gear wheel 16 is located on the outside diameter of the cylindrical section 10, this ,.~
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diameter being eccentric to the central axis of shaft 7, the planet gear wheel 16 is held constantly in mesh with the gear teeth 19 and 21 when the carrier balance weight is rotated about the central axis.
On its lower face, the sun gear 21 has an axial bore 22 provided with a key 23 so that it can engage a simllarly keyed shaft (not shown). The point where the axis of the shaft 7 emerges into the bore 22 may be regarded as the torque output point of the transmission assembly.
As best seen in Fig, 2, a shaft 24 is rotatably mounted in a bore 25 in a collar 29 fixed within a bore in the lower 8eetion 3 of the housing 1 :$
~ and in a bore 26 cut in a flange 27 extending inwardly i~ from, but integral with the lower section 3 of the housing he upper end (to the left of Fig. 2) of the shaft 24 projects from the housing 1 and has a handle 28, whi~ch~can be~turned manually, secured thereto by means of~a pin (~not~shown~ h~e collar 29 is rendered non-rotatable relative to the housin~ by a set sorew 30 which is fixed within a threaded bcre in~the collar 29 and which lle~s wnithln a grocve provided ln the housing 1.
A central~portion of the shaft 24 bears splinès 31~which are engaged With similar splines 32 on the radially-inward surface of a hollow, substantially -.328~
cylindrical worm member 33. Thus, when the shaft 24 is turned by means of the handle 28, the worm member ~:
33 will rotate therewith, but the worm member 33 can still move axially relative to the shaft 24. ~he worm member 33 is provided on its radially-outward surface with two integral flanges 34 and 35 extending radially outwardly therefrom and with a worm thread 36, ~ :
which engages teeth 37 provided on the radially outward surface of the annular member 20. The worm member 33 is also pro~ided with biasing means in the form of a pair of Belleville (multiple plate) springs 38 and 39, which bias it towards the predetermined, central position shown . ~
in Fig. 2. The spring 38 is disposed between the flange - -34 on the worm member 33 and the collar 29, whilst the spring 39 extends between the lower axial end face Of the worm member 33 and the flange 27 on the housing 1.
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A flange 40 extends across the lower section 3 .
of the housing 1 and a cylindri:cal member 41 is rotatably mounted in ~ bore therein. The axial end face of the oylindrical~:member l~bears an eccentric~pin 42 which extends into the groove between the flanges 34 and 35 :on the worm~member 33. Thus, as the WQrm member 33 moves axial1y relat1ve to the shaft 24~ the flanges 34 and 35 will shi~t the pin 42, thereby rotating the oylindrioaLmember 41. A cam (not shown) is provided j;:: :
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on the cylindrical member 41 and a microswitch (also not shown) is disposed adjacent this cam. One side of the microswitch is connected to a power supply and the other side of the microswitch to the electric motor 4.
~he relative dispositions of the cam and microswitch are such that, when the worm member 33, the pin 42 and the cylindrical member 41 are in -their central positions shown in Fig. 2, the cam does not operate the microswitch and thus current can be supplied to the motor 4,.but that if the worm member is shifted axially .
in either direction relative to the shaft 24 by more than -a predetermined amount, the consequent rotation of the cylindrical member 41 causes the cam to open the microswitch, thereby preventing any current supply reaching the motor 4.
The operation of the transmission assembly shown in the accompanying drawings is as follows. The assembly is provided with a reversing switch (not shown) by means of which the electric motor 4 can be made to rotate the cog 5 in either direction. Rotation of the cog 5 rotates the input gear wheel 6 with which it is , in mesh, and the balance weight member 10 rotates with the gear wheel 6. This rotation of the balance weight member 10 forces the teeth 17 on the planet gear wheel 16 to roll along the internal teeth 19 on the annular ~,.................................................. .
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member 20. The eccentric forces caused by rotation of :
the planet gear wheel 16 are balanced by the rotation of the balance weight lOb, which moves in the crescent-shaped prismatic space bounded by the planet gear wheel 16, the annulus 20 and the sun gear 21.
~ he consequent rotation of the planet gear 16 causes the teeth 18 thereon to roll along the teeth on the sun gear 21.' ~he small difference in the numbers of teeth 17 and 18 and the slight difference in internal pitch diameters between the annular member 20 and the sun gear 21 have the effect that the rolling of the teeth 18 along the teeth on the sun gear 21 causes the sun gear to rotate very much more slowly than the input gear wheel 6, the reduction ratio being about 400:1.
A sha~t fixed in the bore 22 in the sun gear 21 wili of course rotate with the sun gear, and the large reduction ratio of the transmission assembly enables a large torque to be.applied to.a shaft fixed in the bore 22 .
even ,though the motor 4 is only capable of producin~
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~ . a small torque. ~he transmission assembly is thus .
;~ very suitable,for use in a valve actuator where the ; space for installing the motor may be limited and yet a ~: large torque may have to be applled to the valve stem of a large diameter valve.
' ~urlng the above-mentioned operation of the ; .
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_12-transmission assembly, -the annular member 20 remains stationary; thus, the transmission assembly is capable of transmitting torque from its torque input point (the point of engagement of the cog 5 with the input gear wheel 6) to its torque output point in the bore 22 whilst its annular member 20 remains stationary~ -Should a shaft fixed in the bore 22 not be able to rotate (for example because a valve member attached thereto has jammed), the sun gear 21 is held stationary and if, under these circumstances, the motor 4 is actuated thereby causing rolling of the planet gear wheel 16 around the interior of the annular member 20, the annular member will be caus~ to rotate. Such rotation of the annular member 20 causes the worm member 33 to slide axially along the shaft 24 against the bias of one of the springs 38 and 39 ~depending upon which way the motor 4 rotates the cog 5), thereby causing ~ ~~
movement of the pin 42 and rotation of the cylindrical member 41. Thls rotation of the cylindrical member 41 opens the aforementioned microswitch, thereby cutting off the~current supply to the motor 4 and~preventing damage thereto. It will be readily appreciated by those skilled in the art that bhe rotation of the oylindrlcal member 41 can be made to actuate a warning device when current cut-off takes place.
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~ ~ ~ 3 If it i5 necessary to use the transmission assembly shown in the accompanying drawings to rotate a shaft fixed in the bore 22 when the motor 4 is inoperative (for example during a power cut), an operative can turn the handle 28, thereby rotating the shaft 24. The worm member 33 rotates with the shaft 24 and, because of the engagement of the worm thread 36 with the external teeth on the annular member 20, the annular member rotates about its own axis. ~his causes rolling of the teeth 17 on the planet gear wheel 16 around the internal teeth 19 on the annular member, whereupon the engagement of the teeth 18 on the planet gear wheel 16 with the teeth-on the sun gear 21 causes the sun gear and the shaft fixed in the bore - 22 to rotate. The handle 28 can be turned in either direction and the shaft fixed in the bore 22..thus made ~^ to rotate in either direction.
.'~ -If the motor 4 suddenly resumes operation whilst an operative is turning the handle 28, no danger -~ to the operat ~ will result. Normally, as described above, operation of the motor 4 does not result in.
rotation of the annular member 20, and evén if the annular member does rotate, it will not rotate the, ~.y. ~ .
shaft 24 but simply cause the worm member 33 to slide axially along the shaft 24.
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The transmission assembly described above has been found to be particularly suitable for use in actuating a valve such as a butterfly valve for closing a pipe or the like. When the assembly is to be used for such a purpose a shaft connected to the butterfly valve is fitted into the bore 22 i.e. the torque output point. ~he butterfly valve can then be rotated by means of the transmission assembly.
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of the transmission assembly.
The input gear wheel 6 is rotatable about the ~
axis of a shaft 7 which extends through a central .:
aperture in the gear wheel 6. A sleeve member 8 , . .
,;l encircles the shaft 7~ being held in position by a ,.-' shoulder 9 thereon. Ball races are provided on the ~ '~
.,. ~ radially-outward surfaoe of the~sleeve member 8 and on .''~
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the radia11y-1nward~ surface of a balanoe weight member 10 which enoircles the sleeve member 8. A plurality of balls ll held between the ball races on the sleeve member 8 and the balance weight member :10 render the latter rotatable relative to the shaft 7 about the axis thereof~ -and slnce the 1nput gear wheel 6 is fixed to the balance weight member 8Iby a,bolt 12, the input gear wheel 6 is thus rendered rotat O le about the axis of the shaft 7.
: The balance weight member 10 comprises three ~ ~ 3 sections, namely an annular section lOa, which abuts and is fixed to the gear wheel 6, a crescent-shaped balance weight lOb which depends downwardly from one side of the annular section lOa, and a hollow cylindrical section lOc, which also depends downwardly from the annular section lOa; all three sections are integral with one another. ~he outside diameter of the cylindrical section lOc is off-set from the axis of the shaft 7 and within the cylindrical section lOc a bore of the cylindrical section lOc is concentric with the shaft 7. Wibl~nthe bore of the cylindrical section lOc is located a roller bearing assembly 14 in position around the lower part of the shaft 7, thus ensuring free rotation of the cylindrical section lOc about the shaft 7.
~ he radially-outward æurface of the cylindrical section lOc is provided with a ball race, and a plurality of balls 15 are held between this ball race and a further ball race provided on the radially-inward surface of a planet gear wheel 16, which is thus rendered freely rotatable about the cylindrical aection lOc. ~he radially-outward surface of the planet gear wheel 16 bears two sets of straight-cut teeth, namely an upper set 17 comprising fifty-six teeth and a lower set 18 .~ . .
comprising fifty-five teeth. As best see in ~ig. 1 the pitch diameter of the upper set of teeth 17 is ~ .
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slightly greater than that of the lower set 18.
~ he upper set of teeth 17 are meshed with straight-cut teeth 19 on the radially-inward surface of an annular member 20 whose axis coincides with that of the shaft 7. As shown in Fig. 3, because the pitch diameter of the teeth 17 is approximately 85% of the pitch diameter of the teeth 19, about eight teeth in each set are always meshed with the other set. This reduces the load on the teeth in mesh, enabling straight-cut rather than helical teeth to be used and also permitting the use of narrower teeth than would have been possible had only one or two teeth in each set been meshed with the other set.
The lower set of teeth 18 on the planet gear wheel are meshed with teeth on the radially inward surface of a sun gear 21 which is integral with and centered on the shaft 7. The pitch diameter of the teeth 18 is about 85~o of the pitch diameter of the teeth on the sun gear 21 so that about eight teeth .
of each set are always in mesh with the teeth of the ~ other set, with the resultant advantages discussed ;'~ above with reference to the teeth 17 and 19.
Since the planet gear wheel 16 is located on the outside diameter of the cylindrical section 10, this ,.~
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diameter being eccentric to the central axis of shaft 7, the planet gear wheel 16 is held constantly in mesh with the gear teeth 19 and 21 when the carrier balance weight is rotated about the central axis.
On its lower face, the sun gear 21 has an axial bore 22 provided with a key 23 so that it can engage a simllarly keyed shaft (not shown). The point where the axis of the shaft 7 emerges into the bore 22 may be regarded as the torque output point of the transmission assembly.
As best seen in Fig, 2, a shaft 24 is rotatably mounted in a bore 25 in a collar 29 fixed within a bore in the lower 8eetion 3 of the housing 1 :$
~ and in a bore 26 cut in a flange 27 extending inwardly i~ from, but integral with the lower section 3 of the housing he upper end (to the left of Fig. 2) of the shaft 24 projects from the housing 1 and has a handle 28, whi~ch~can be~turned manually, secured thereto by means of~a pin (~not~shown~ h~e collar 29 is rendered non-rotatable relative to the housin~ by a set sorew 30 which is fixed within a threaded bcre in~the collar 29 and which lle~s wnithln a grocve provided ln the housing 1.
A central~portion of the shaft 24 bears splinès 31~which are engaged With similar splines 32 on the radially-inward surface of a hollow, substantially -.328~
cylindrical worm member 33. Thus, when the shaft 24 is turned by means of the handle 28, the worm member ~:
33 will rotate therewith, but the worm member 33 can still move axially relative to the shaft 24. ~he worm member 33 is provided on its radially-outward surface with two integral flanges 34 and 35 extending radially outwardly therefrom and with a worm thread 36, ~ :
which engages teeth 37 provided on the radially outward surface of the annular member 20. The worm member 33 is also pro~ided with biasing means in the form of a pair of Belleville (multiple plate) springs 38 and 39, which bias it towards the predetermined, central position shown . ~
in Fig. 2. The spring 38 is disposed between the flange - -34 on the worm member 33 and the collar 29, whilst the spring 39 extends between the lower axial end face Of the worm member 33 and the flange 27 on the housing 1.
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A flange 40 extends across the lower section 3 .
of the housing 1 and a cylindri:cal member 41 is rotatably mounted in ~ bore therein. The axial end face of the oylindrical~:member l~bears an eccentric~pin 42 which extends into the groove between the flanges 34 and 35 :on the worm~member 33. Thus, as the WQrm member 33 moves axial1y relat1ve to the shaft 24~ the flanges 34 and 35 will shi~t the pin 42, thereby rotating the oylindrioaLmember 41. A cam (not shown) is provided j;:: :
~. - . . . : . : . . ..
~132~3 --1~
on the cylindrical member 41 and a microswitch (also not shown) is disposed adjacent this cam. One side of the microswitch is connected to a power supply and the other side of the microswitch to the electric motor 4.
~he relative dispositions of the cam and microswitch are such that, when the worm member 33, the pin 42 and the cylindrical member 41 are in -their central positions shown in Fig. 2, the cam does not operate the microswitch and thus current can be supplied to the motor 4,.but that if the worm member is shifted axially .
in either direction relative to the shaft 24 by more than -a predetermined amount, the consequent rotation of the cylindrical member 41 causes the cam to open the microswitch, thereby preventing any current supply reaching the motor 4.
The operation of the transmission assembly shown in the accompanying drawings is as follows. The assembly is provided with a reversing switch (not shown) by means of which the electric motor 4 can be made to rotate the cog 5 in either direction. Rotation of the cog 5 rotates the input gear wheel 6 with which it is , in mesh, and the balance weight member 10 rotates with the gear wheel 6. This rotation of the balance weight member 10 forces the teeth 17 on the planet gear wheel 16 to roll along the internal teeth 19 on the annular ~,.................................................. .
,;
~LS 13Z~
member 20. The eccentric forces caused by rotation of :
the planet gear wheel 16 are balanced by the rotation of the balance weight lOb, which moves in the crescent-shaped prismatic space bounded by the planet gear wheel 16, the annulus 20 and the sun gear 21.
~ he consequent rotation of the planet gear 16 causes the teeth 18 thereon to roll along the teeth on the sun gear 21.' ~he small difference in the numbers of teeth 17 and 18 and the slight difference in internal pitch diameters between the annular member 20 and the sun gear 21 have the effect that the rolling of the teeth 18 along the teeth on the sun gear 21 causes the sun gear to rotate very much more slowly than the input gear wheel 6, the reduction ratio being about 400:1.
A sha~t fixed in the bore 22 in the sun gear 21 wili of course rotate with the sun gear, and the large reduction ratio of the transmission assembly enables a large torque to be.applied to.a shaft fixed in the bore 22 .
even ,though the motor 4 is only capable of producin~
,~
~ . a small torque. ~he transmission assembly is thus .
;~ very suitable,for use in a valve actuator where the ; space for installing the motor may be limited and yet a ~: large torque may have to be applled to the valve stem of a large diameter valve.
' ~urlng the above-mentioned operation of the ; .
,,,", ..
,~; . , ,: : :,:
''~.: :~ ' ': . . , . : . .
;~ ` ~ ::: :
1~132~3~
_12-transmission assembly, -the annular member 20 remains stationary; thus, the transmission assembly is capable of transmitting torque from its torque input point (the point of engagement of the cog 5 with the input gear wheel 6) to its torque output point in the bore 22 whilst its annular member 20 remains stationary~ -Should a shaft fixed in the bore 22 not be able to rotate (for example because a valve member attached thereto has jammed), the sun gear 21 is held stationary and if, under these circumstances, the motor 4 is actuated thereby causing rolling of the planet gear wheel 16 around the interior of the annular member 20, the annular member will be caus~ to rotate. Such rotation of the annular member 20 causes the worm member 33 to slide axially along the shaft 24 against the bias of one of the springs 38 and 39 ~depending upon which way the motor 4 rotates the cog 5), thereby causing ~ ~~
movement of the pin 42 and rotation of the cylindrical member 41. Thls rotation of the cylindrical member 41 opens the aforementioned microswitch, thereby cutting off the~current supply to the motor 4 and~preventing damage thereto. It will be readily appreciated by those skilled in the art that bhe rotation of the oylindrlcal member 41 can be made to actuate a warning device when current cut-off takes place.
:
~ .
,.) i ( ; . . . . : :: . : . ..
), ~ . .
:.~ , , , . ,:..... .. ~: -., . . . . , - -: .. :. , ~.
~ . , .:: . .
~ ~ ~ 3 If it i5 necessary to use the transmission assembly shown in the accompanying drawings to rotate a shaft fixed in the bore 22 when the motor 4 is inoperative (for example during a power cut), an operative can turn the handle 28, thereby rotating the shaft 24. The worm member 33 rotates with the shaft 24 and, because of the engagement of the worm thread 36 with the external teeth on the annular member 20, the annular member rotates about its own axis. ~his causes rolling of the teeth 17 on the planet gear wheel 16 around the internal teeth 19 on the annular member, whereupon the engagement of the teeth 18 on the planet gear wheel 16 with the teeth-on the sun gear 21 causes the sun gear and the shaft fixed in the bore - 22 to rotate. The handle 28 can be turned in either direction and the shaft fixed in the bore 22..thus made ~^ to rotate in either direction.
.'~ -If the motor 4 suddenly resumes operation whilst an operative is turning the handle 28, no danger -~ to the operat ~ will result. Normally, as described above, operation of the motor 4 does not result in.
rotation of the annular member 20, and evén if the annular member does rotate, it will not rotate the, ~.y. ~ .
shaft 24 but simply cause the worm member 33 to slide axially along the shaft 24.
.!
, . .
' ~13Z~
The transmission assembly described above has been found to be particularly suitable for use in actuating a valve such as a butterfly valve for closing a pipe or the like. When the assembly is to be used for such a purpose a shaft connected to the butterfly valve is fitted into the bore 22 i.e. the torque output point. ~he butterfly valve can then be rotated by means of the transmission assembly.
,,.,~; , ' ' .
ï ~
~ .
~' .
` .
, :
; ~ ' ' .- , : -,' ' : ~ ' . ' `
.. : . : , , , , ., . '-: -: ' ' . . '' .,: ~ . :
Claims (10)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A transmission assembly having a power input member and a power output member interconnected by an epicyclic gear train interconnecting said members, said gear train incorporating at least one sun gear element rotatable about its axis and formed with peripheral teeth, a driving shaft, a worm splined on said driving shaft and resiliently held in a datum position against axial movement from the datum position, said worm engaging said peripheral teeth on said sun gear element, a circumferential groove formed adjacent at least one end of the worm, and a detecting device incorporating a projection extending into said groove whereby when the worm moves axially on the driving shaft from its datum position by a predetermined amount the projection is correspondingly moved to control the power input to the transmission assembly.
2. A transmission assembly as claimed in claim 1, in which the detection device comprises a rotary cam member mounted o proximity to the worm, said rotary cam member comprising an eccentric pin which extends into the circumfrential groove in the worm, whereby rotary movement of the cam member controlling the power input to the transmission assembly.
3. A transmission assembly as claimed in claim 1 in which an electric motor having a control circuit is operatively connected to the power input member and the detecting device incorporates an electric switch connected into said control circuit.
4 A transmission assembly as claimed in claim 1 incorporating two rotatable sun gear elements coaxial with one another and formed with different numbers of teeth and a planet gear having two coaxial gear elements fixed to one another and arranged to perform an orbital motion around the sun gear element with each planet gear element in mesh with a respective sun gear element, the power input shaft being coupled to the planet gear so as to be capable of imparting said orbital motion to the planet gear, one of said sun gear elements being that in meshing engagement with the worm and the other sun gear element being connected to the power output member.
5. A transmission assembly as claimed in claim 1 .
in which spring means is provided on the driving shaft to encircle the driving shaft and press against at least one end of the worm whereby to urge the worm to the datum position.
in which spring means is provided on the driving shaft to encircle the driving shaft and press against at least one end of the worm whereby to urge the worm to the datum position.
6. A transmission assembly as claimed in claim 5 in which spring means presses against both ends of the worm so that they act in opposition to hold the worm resiliently in its datum position.
7. A transmission assembly as claimed in claim 5 in which the spring means is formed of at least one stack of Belleville washers.
8. A transmission assembly as claimed in claim 4 in which an extension of the power output member acts as a support for the planet gear and for the sun gear element meshing with the worm, bearing means mounting said sun gear element and planet gear on the power ouput member extension.
9. A transmission assembly as claimed in claim 4 in which there is attached to the power input member a balance weight arranged in substantially co-planar disposition relative to the planet gear and at the opposite side of- the axis of the power input member from the axis of the planet gear.
10. A transmission assembly as claimed in claim 4 in which the sun gear elements are both in the form of rings formed with internal teeth, the sun gear element meshing with the worm is formed with external. teeth meshing with the worm, the planet gear is located within said rings and meshes with the internal teeth and a balance weight attached to the power input member is located within the rings to occupy a part of the crescent shaped space defined by the portion of the periphery of the planet gear not in mesh with the sun gear elements and the portion of the periphery of the sun gear elements not engaged with the planet gear.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1387778 | 1978-04-08 | ||
| GB13877/78 | 1978-04-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1113280A true CA1113280A (en) | 1981-12-01 |
Family
ID=10031002
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA325,073A Expired CA1113280A (en) | 1978-04-08 | 1979-04-06 | Transmission assembly for powered and manual operation |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS54148961A (en) |
| BR (1) | BR7902151A (en) |
| CA (1) | CA1113280A (en) |
| DE (1) | DE2914364A1 (en) |
| FR (1) | FR2422085A1 (en) |
| IT (1) | IT1112200B (en) |
| NL (1) | NL7902712A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112413059A (en) * | 2020-12-17 | 2021-02-26 | 江苏泰隆减速机股份有限公司 | Door descending speed reducer for ship |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3138004C2 (en) * | 1981-09-24 | 1985-01-31 | Elektro-Mechanik Gmbh, 5963 Wenden | Actuator with a planetary gear |
| US4616803A (en) * | 1983-08-23 | 1986-10-14 | Keystone International, Inc. | Declutchable valve override |
| DE4344325A1 (en) * | 1993-12-23 | 1995-06-29 | Dieter Prof Dr Ing Heuer | Planetary gear especially for actuators for mountings |
| JP2888329B2 (en) * | 1995-05-23 | 1999-05-10 | 日本サーボ株式会社 | Manual operation mechanism |
| DE102007007680B3 (en) * | 2007-02-16 | 2008-06-19 | Nurkraft Gmbh | Adjusting drive unit for a ball valve comprises a transmission arranged between a hand wheel and a drive motor |
| CN109681690B (en) * | 2018-12-28 | 2021-02-02 | 常州市汇丰船舶附件制造有限公司 | Speed reducer of intelligent valve actuator |
| US12000130B2 (en) | 2021-12-18 | 2024-06-04 | B/E Aerospace, Inc. | Vacuum toilet override systems and methods |
| EP4198216A3 (en) * | 2021-12-18 | 2023-09-13 | B/E Aerospace, Inc. | Vacuum toilet override systems and methods |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DD3829A (en) * | ||||
| AT135267B (en) * | 1931-11-26 | 1933-11-10 | Schaeffer & Budenberg Gmbh | Motorized drive device for shut-off devices. |
| US2206597A (en) * | 1934-04-07 | 1940-07-02 | American Rolling Mill Co | Coating metal articles |
| DE1129790B (en) * | 1959-07-02 | 1962-05-17 | Rotork Engineering Company Ltd | Valve drive that can be operated either manually or by an electric motor |
| DE1231517B (en) * | 1964-04-25 | 1966-12-29 | Siebeck Metallwerk G M B H | Motorized actuator for valves or the like with worm gear |
| DE1550502A1 (en) * | 1966-04-28 | 1970-01-08 | Siemens Ag | Electric actuator |
| DE1675483B1 (en) * | 1968-03-01 | 1971-04-22 | Baelz Gmbh Helmut | MANUAL ADJUSTMENT DEVICE FOR MOTOR-DRIVEN VALVES |
| GB1252564A (en) * | 1968-05-31 | 1971-11-10 | ||
| JPS5035990B2 (en) * | 1971-09-08 | 1975-11-20 |
-
1979
- 1979-04-05 FR FR7908610A patent/FR2422085A1/en active Granted
- 1979-04-06 IT IT21648/79A patent/IT1112200B/en active
- 1979-04-06 NL NL7902712A patent/NL7902712A/en not_active Application Discontinuation
- 1979-04-06 BR BR7902151A patent/BR7902151A/en unknown
- 1979-04-06 CA CA325,073A patent/CA1113280A/en not_active Expired
- 1979-04-09 DE DE19792914364 patent/DE2914364A1/en not_active Withdrawn
- 1979-04-09 JP JP4338679A patent/JPS54148961A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112413059A (en) * | 2020-12-17 | 2021-02-26 | 江苏泰隆减速机股份有限公司 | Door descending speed reducer for ship |
| CN112413059B (en) * | 2020-12-17 | 2024-06-07 | 江苏泰隆减速机股份有限公司 | Marine door lowering speed reducer |
Also Published As
| Publication number | Publication date |
|---|---|
| NL7902712A (en) | 1979-10-10 |
| IT7921648A0 (en) | 1979-04-06 |
| FR2422085A1 (en) | 1979-11-02 |
| JPS54148961A (en) | 1979-11-21 |
| BR7902151A (en) | 1979-12-04 |
| IT1112200B (en) | 1986-01-13 |
| FR2422085B1 (en) | 1984-05-25 |
| DE2914364A1 (en) | 1979-10-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |