CA1045182A - Safety device for guarded machinery - Google Patents
Safety device for guarded machineryInfo
- Publication number
- CA1045182A CA1045182A CA247,708A CA247708A CA1045182A CA 1045182 A CA1045182 A CA 1045182A CA 247708 A CA247708 A CA 247708A CA 1045182 A CA1045182 A CA 1045182A
- Authority
- CA
- Canada
- Prior art keywords
- safety device
- unit
- keying
- keying means
- stop
- 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
- 238000000926 separation method Methods 0.000 claims abstract description 3
- 230000001960 triggered effect Effects 0.000 claims description 3
- 230000000694 effects Effects 0.000 claims description 2
- 238000003780 insertion Methods 0.000 claims description 2
- 230000037431 insertion Effects 0.000 claims description 2
- 244000228957 Ferula foetida Species 0.000 description 1
- 208000027418 Wounds and injury Diseases 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000000994 depressogenic effect Effects 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 208000014674 injury Diseases 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 239000004753 textile Substances 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
- F16P—SAFETY DEVICES IN GENERAL; SAFETY DEVICES FOR PRESSES
- F16P3/00—Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body
- F16P3/08—Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body in connection with the locking of doors, covers, guards, or like members giving access to moving machine parts
-
- 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
- F16P—SAFETY DEVICES IN GENERAL; SAFETY DEVICES FOR PRESSES
- F16P3/00—Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Looms (AREA)
- Knitting Machines (AREA)
- Switch Cases, Indication, And Locking (AREA)
- Lock And Its Accessories (AREA)
- Drying Of Solid Materials (AREA)
- Power-Operated Mechanisms For Wings (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
This invention relates to a safety device comprising a first unit which is adapted for connection to a fixed struc-ture of machinery and which includes electrical switching means for controlling power to the machinery. A second unit is adapted for connection to a door, cover or guard and includes manually operable keying means which is movable between successive OPEN, OFF and ON positions and is engageable with and disengageable from said first unit when in the OPEN
position and co-operates with the first unit to prevent separa-tion of the two units when engaged with the first unit and moved to the OFF and ON positions. The keying means further controlling operation of the switching means when both units are engaged so that power is connected to the machinery only when the keying means is in the ON positron; and delay means which is operative on movement of said keying means from the ON to the OFF position and which then acts for a limited time to positively prevent movement of the keying means from the OFF to the OPEN position.
This invention relates to a safety device comprising a first unit which is adapted for connection to a fixed struc-ture of machinery and which includes electrical switching means for controlling power to the machinery. A second unit is adapted for connection to a door, cover or guard and includes manually operable keying means which is movable between successive OPEN, OFF and ON positions and is engageable with and disengageable from said first unit when in the OPEN
position and co-operates with the first unit to prevent separa-tion of the two units when engaged with the first unit and moved to the OFF and ON positions. The keying means further controlling operation of the switching means when both units are engaged so that power is connected to the machinery only when the keying means is in the ON positron; and delay means which is operative on movement of said keying means from the ON to the OFF position and which then acts for a limited time to positively prevent movement of the keying means from the OFF to the OPEN position.
Description
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This invention relates to a safety device for ~ locking a door, cover or the like openable or removable guard which is normally kept locked to guard machinery or an area which is potentially hazardous.
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British Patent No. 1 260 322 discloses a safety , device comprising a lock unit for connection to a fixed structure of machinery, and a captive key unit for connection to a door, cover or guard of the machinery, ~the two units being adapted so that they can be engaged and locked together by rotation of the captive key when the door is closed. The lock unit also incorporates electrical switching means which is controlled by ~' rotation of the captive key and which in turn controls ' , ',' the power supply to the machinery so that power is ~- '`'' connected only when the two units are locked together '~
and is disconnected when the captive key is turned to an OPEN position in which the two units can be freely disengaged and engaged to open and close the door. ~ ,, This known safety device is adequate for machinery ~' ' which is rendered safe as soon as the power supply is i~ ','-disconnected. ~Iowever, it is not ade~uate for machinery -' which remains potentially dangerous for some time after ~ :-power is disconnected, because the door can then be ~' opened ,while the machinery is still in a dangerous state. ,`~''~1 ' For example, the machinery may have rotating parts which 1 '';
do not come to rest immediately power is disconnected, either because of the inertia of these parts or because ~1',' ;
they are stopped gradually, such as in a textile mill , ';
to prevent the breaking of fibres. An object of the , ~,;,, present invention is to provide a safety device which ' ' , overcomes this shortcoming of the known safety device.
: . , .~:: :: . ~
The present invention consists in a safety device comprising a first unit which is adapted for connection '. .' to a fixed structure of machinery and which includes ' , '" , electrical switching means for controlling power to the machinery; a second unit which is adapted for connection to a door, cover or guard and which includes manuaIly ¦' operable keying means wh~ich is movable between successive '"' - ~ . I.: ::
, . 2 .
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OPEN, OFF and ON positions and is engagable with and disen~ageable from said first unit when in the OPEN -.
position and co-operates with the first unit to prevent separation of the two units when engaged with the first unit and moved to the OFF and ON positions, the keying .
means further controlling operation of the switching means when both units are engaged so that power is :
connected to the machinery on:Ly when the keying means is : .
in the ON position; and delay means which is operative on ~ .
movement of said keying means from the ON to the OFF
position and which then acts for a limited time to positively prevent movement of the keying means from the OFF to the OPEN position. Said limited time is such as to allow dangerous conditions in the machinery to abate following disconnection of power, the time being either a predetermined time or a time determined by sensor means which senses said dangerous conditions.
. The delay means preferably comprises mechanical stop means which arrests the keying means in the OFF
position and timer means which is triggered when the keying means reaches said OFF position and which, a predetermined time thereafter, operates the stop means ~: :
to allow continued movement of the keying means to the OPEN position. ~
The keying means may comprise a rotatable key ~::.~-captive in the second unit and having laterally extending .~
lugs which are insertable through corresponding slots ~-in the first unit when the key is in ~he OPEN position and which co-operate with abutment surfaces in the .~
first unit to prevent withdrawal of the key when the ~ -latter is inserted into the first unit and turned:to ~ :
the ON position. . .:
Further, said key may be provided with bittings :., which engage a cylinder lock mechanism in the first -unit to effect release of a lock spindle, the lugs of the key engaging corresponding grooves in the lock spindle so that the key and lock spindle rotate together, ~ ..
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rotation of the lock spindle in turn controlling operation of the electrical switching means. By these means operation of the-switching means by any~hing other than the captive key o~ the second unit is prevented so that the guard must be closed and the two units locked together before the switchinc~ means can be operated to connect power to the guarded machinery.
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The invention will now be described by way of example with reference to the accompanying drawings in which:-Figure 1 is a side elevation of an embodiment of the invention, .~ ~, . . .
Figure 2 is a plan view of the embodiment of Figure 1, ;
Figure 3 is a view along the line 3-3 in Figure 2, and `' '~ . ,:
Fi~ure 4 is a perspective of the captive key unit and lock unit of Figures 1 and 2.
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Figures 1 to 4 o~ the drawings show a safety device comprising two-separate units, one of which units 1 - ~ -f comprises a casing 2 which houses a lock body 3 and is ~-adapted for connection to the frame 4 of machinery to be guarded~ and the other of which units 5 comprises a ~-captive key body 6 which is adapted for connection to , i a door, cover or guard 7 provided on the frame ~ and which slidably and -rotatably supports a control knob 8 and a key 9 which is adapted to co-operate with the lock body 3 as hereinafter described to lock both units 1 ~
and 5 together with the guard 7 closed. ~;
The control knob 8 is a hollow cylindrical member which fits telescopically over the key body 6 and which has the key 9 pro~ecting axially from it inside. The key 9 is a slidable and rotatable fit in a bore in the key body 6 and is hollowed out at its free -- ,, ' .
, 4 .
: .
:
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end to form a key bit 10 with a cylindrical socket to engage a locating peg 11 in the lock body 3. Two laterally extending diametrically opposed key lugs 12 are formed at the extremity of the key bit 10 and these are received in a corresponding pair of guide recesses 13 in the key body 6 when the door 7 is open and the control knob 8 is released, as shown in Figure 1, a coil spring 14 then acting between the head of the control knob and the key body to retract the key into the key body.
l~ The lock body 3 houses a cylinder lock mechanism of the axial pin tumbler type comprising a barrel or pin tumbler holder 15 fixed in the body 3 and a co-operating rotatable barrel or pin tumbler holder 16 which is integral with a lock spindle 17 rotatable in the body 3.
The lock body 3 has a coned face bezel 18 `
to engage a corresponding coned seating l9 on the key body. In the front wall of the bezel a keyhole 20 is formed -comprising a central hole to receive the key bit 10 and a , pair of diametrically opposed slots 21 to receive the key ~o lugs 12 on the key bit. Further, the lock spindle 17 is ' -~
formed with a pair of diametrically opposed grooves 22 in its barrel 16 to receive the key lugs 12.
When-the door 7 is-closed the seating 19 on the key body 6 engages-the bezel 18 on the lock body 3.
The control knob 8 can then be depressed against the action of the spring 14 to insert the key bit 10 through the keyhole 20, it being guided by the locating peg 11 and the key lugs 12 passing through the slots 21 in the bezel 18 on the lock body and enyaging the grooves 22 in the barrel 16 on the lock spindle 17. Key bittings 23 are provided circumferentially between the key lugs 12 in the end of the key bit 10 (see Figure 4), and these co-operate with the pin tumblers 24 of the cylinder lock mechanism in the lock body 3 (as shown in Figure 1) to release the barrel 16 for rotation of the lock spindle by the key 9 acting through the key lugs 12 in the grooves 22. In turning the key 9 and lock spindle 17, the key lugs 12 move behind the portions of the front :
, . . ..
, ~4S~82 wall of the bezel 18 which lie between the keyhole slots 20 and which form abutment surfaces against which the key lugs engage to lock the two units 1 and 5 together.
-The lock spindle 17 is connected by a sleeve 25to a further spindle 26 which carries the cams 27,28 of each of two electrical switches 29j30, respectively.
Both switches are o~ the type in which the cam controls ~`
the position of a bridge member which serves to form a bridging connection between input and output terminals \a of the switch. The one switch 29 is connected so as to control the supply of power to the machinery being guarded and serves to connect power only when the two units 1 and 5 are locked together with the control knob 8 ~
in an ON position. From this O~ position the control -knob can be turned towards an OPEN position in which the two units 1 and 5 are unlocked, the key 3 then being disengageable from the lock body 3. Between these two positions the control knob assumes an OFF position in which the switch 29 disconnects power from the machinery ~;
being guarded but in which the two units 1 and 5 are still locked together.
The safety device therefore protects personnel against injury by preventing the connection of power to the machinery unless the door 7 is closed and locked : -- by depression and rotation of the control knob 8 to the ON position. Subse~uent unlocking of the door automatically disconnects the power. The provision of the coded bittings 23 on the key to operate the lock -tumbler mechanism makes it impossible to connect power to the unguarded machinery by insertion of a simple object through the keyhole in the lo~k body. ~:
- ' :' ::,:'',.
The safety device described so far is as disclosed ;
in our Patent No. 1 260 322. However, the present device ~ , is further modified according to the present in~ention by providing delay means which, when units 1 and 5 are Iocked together, responds to turning of the control knob from the ON to the OFF position by introducing a tlme ~ : i ' ' ~ ..... ,-. ~ ' ~':. ~.
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delay before the control knob can be turner further to the OPEN position.
The delay means includes a solenoid-operated plunger 31 which is mounted within the casing 2 so as to extend parallel to the lock spindle 17 and to co-operate with a cam plate 32 which is connected to the sleeve 25. When the solenoid is de-energised and the control knob 8 is in the ON and OFF positions, ; the plunger 31 is spring urged outwardly of the solenoid V so that its outer end engages in a peripheral notch 33 in the- cam plate 32 (see Figure 3). In the ON position, the plunger 31 engages one end of the notch 33 and in the OFF position the plunger 31 engages the other end of the notch, as shown in Figure 3. The plunger 31 then prevents the control knob from being turned further i to the OPEN position. The delay means further comprises ~`
the electrical switch 30 and a timer circuit 34 which is controlled by the switch 30 and which in turn controls;~
energisation of the solenoid oE plunger 31. The switch 30 ~Dis operated when the control knob reaches thè OFF position and then triggers the timer circuit 34 which in turn energises the solenoid after a predetermined time delay.
The plunger 31 is thereby withdrawn from the notch 33 in cam plate 32, whereupon the control knob can be -turned to the OPEN position and the door 7 opened.
The predetermined time delay o the timer circuit is selected so as to allow dangerous conditions in the machinery to abate before the door can be opened. i ~. :
- In an alternative embodiment of the invention, ~V the timer circuit 34 of the illustrated embodiment may be replaced by sensor means which senses the existence ~
of a potentially dangerous condition in the guarded -machinery and energises the solenoid of plunger 31 only when this condition has abated. The sensor means may be triggered by a switch, such as the switch 30, so as to operate only after the control knob 8 is turned from the ON to the OFF position. Alternatively, the sensor means may operate continuously to sense said potentially dangerous condition and to allow energisation ' ` ` ' ` , , ~ ~ . 7 .
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of the solenoid only when said condition abates ~ irrespective of whether the control knob is in the I ON or OFF position.
! It will be appreciated that failure of the solenoid `. circuitry will prevent energisation of the solenoid, whereupon the control knob will be locked in the Oi~
or OFF position and the two units 1 and 5 will be locked together. The illustrated safety device is therefore "fail-safe" in design.
o- It will be further appreciated that the position of the cam plate 32 is not important and that it may be preferable to mount it on the shaft 26 on the other side of the switches 29,30 from the lock body 3~ The solenoid-operated plunger 31 would then be suitably relocated.
Further, although the illustrated embodiment is provided with a tumbler lock mechanism so as to prevent rotation of the lock spindle by insèrtion of a simple object into the keyhole, it will be appreciated that ~ -~0 this tumbler lock mechanism can be omitted either from the illustrated embodiment or any of the other embodiments described above. This does allow the possibility of rotation of the lock spindle by means other than the captive key in the key body, but this may be acceptable in some non-industrial applications, - for example in domestic appliances such as spin driers.; <~
,. . .:
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- . ;, :
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45~.8Z
. . .
This invention relates to a safety device for ~ locking a door, cover or the like openable or removable guard which is normally kept locked to guard machinery or an area which is potentially hazardous.
..
British Patent No. 1 260 322 discloses a safety , device comprising a lock unit for connection to a fixed structure of machinery, and a captive key unit for connection to a door, cover or guard of the machinery, ~the two units being adapted so that they can be engaged and locked together by rotation of the captive key when the door is closed. The lock unit also incorporates electrical switching means which is controlled by ~' rotation of the captive key and which in turn controls ' , ',' the power supply to the machinery so that power is ~- '`'' connected only when the two units are locked together '~
and is disconnected when the captive key is turned to an OPEN position in which the two units can be freely disengaged and engaged to open and close the door. ~ ,, This known safety device is adequate for machinery ~' ' which is rendered safe as soon as the power supply is i~ ','-disconnected. ~Iowever, it is not ade~uate for machinery -' which remains potentially dangerous for some time after ~ :-power is disconnected, because the door can then be ~' opened ,while the machinery is still in a dangerous state. ,`~''~1 ' For example, the machinery may have rotating parts which 1 '';
do not come to rest immediately power is disconnected, either because of the inertia of these parts or because ~1',' ;
they are stopped gradually, such as in a textile mill , ';
to prevent the breaking of fibres. An object of the , ~,;,, present invention is to provide a safety device which ' ' , overcomes this shortcoming of the known safety device.
: . , .~:: :: . ~
The present invention consists in a safety device comprising a first unit which is adapted for connection '. .' to a fixed structure of machinery and which includes ' , '" , electrical switching means for controlling power to the machinery; a second unit which is adapted for connection to a door, cover or guard and which includes manuaIly ¦' operable keying means wh~ich is movable between successive '"' - ~ . I.: ::
, . 2 .
i.. ~
~04~
OPEN, OFF and ON positions and is engagable with and disen~ageable from said first unit when in the OPEN -.
position and co-operates with the first unit to prevent separation of the two units when engaged with the first unit and moved to the OFF and ON positions, the keying .
means further controlling operation of the switching means when both units are engaged so that power is :
connected to the machinery on:Ly when the keying means is : .
in the ON position; and delay means which is operative on ~ .
movement of said keying means from the ON to the OFF
position and which then acts for a limited time to positively prevent movement of the keying means from the OFF to the OPEN position. Said limited time is such as to allow dangerous conditions in the machinery to abate following disconnection of power, the time being either a predetermined time or a time determined by sensor means which senses said dangerous conditions.
. The delay means preferably comprises mechanical stop means which arrests the keying means in the OFF
position and timer means which is triggered when the keying means reaches said OFF position and which, a predetermined time thereafter, operates the stop means ~: :
to allow continued movement of the keying means to the OPEN position. ~
The keying means may comprise a rotatable key ~::.~-captive in the second unit and having laterally extending .~
lugs which are insertable through corresponding slots ~-in the first unit when the key is in ~he OPEN position and which co-operate with abutment surfaces in the .~
first unit to prevent withdrawal of the key when the ~ -latter is inserted into the first unit and turned:to ~ :
the ON position. . .:
Further, said key may be provided with bittings :., which engage a cylinder lock mechanism in the first -unit to effect release of a lock spindle, the lugs of the key engaging corresponding grooves in the lock spindle so that the key and lock spindle rotate together, ~ ..
~'..'.' . 3. ~:
-- . --lQ4~8X
rotation of the lock spindle in turn controlling operation of the electrical switching means. By these means operation of the-switching means by any~hing other than the captive key o~ the second unit is prevented so that the guard must be closed and the two units locked together before the switchinc~ means can be operated to connect power to the guarded machinery.
.
The invention will now be described by way of example with reference to the accompanying drawings in which:-Figure 1 is a side elevation of an embodiment of the invention, .~ ~, . . .
Figure 2 is a plan view of the embodiment of Figure 1, ;
Figure 3 is a view along the line 3-3 in Figure 2, and `' '~ . ,:
Fi~ure 4 is a perspective of the captive key unit and lock unit of Figures 1 and 2.
.
.
Figures 1 to 4 o~ the drawings show a safety device comprising two-separate units, one of which units 1 - ~ -f comprises a casing 2 which houses a lock body 3 and is ~-adapted for connection to the frame 4 of machinery to be guarded~ and the other of which units 5 comprises a ~-captive key body 6 which is adapted for connection to , i a door, cover or guard 7 provided on the frame ~ and which slidably and -rotatably supports a control knob 8 and a key 9 which is adapted to co-operate with the lock body 3 as hereinafter described to lock both units 1 ~
and 5 together with the guard 7 closed. ~;
The control knob 8 is a hollow cylindrical member which fits telescopically over the key body 6 and which has the key 9 pro~ecting axially from it inside. The key 9 is a slidable and rotatable fit in a bore in the key body 6 and is hollowed out at its free -- ,, ' .
, 4 .
: .
:
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end to form a key bit 10 with a cylindrical socket to engage a locating peg 11 in the lock body 3. Two laterally extending diametrically opposed key lugs 12 are formed at the extremity of the key bit 10 and these are received in a corresponding pair of guide recesses 13 in the key body 6 when the door 7 is open and the control knob 8 is released, as shown in Figure 1, a coil spring 14 then acting between the head of the control knob and the key body to retract the key into the key body.
l~ The lock body 3 houses a cylinder lock mechanism of the axial pin tumbler type comprising a barrel or pin tumbler holder 15 fixed in the body 3 and a co-operating rotatable barrel or pin tumbler holder 16 which is integral with a lock spindle 17 rotatable in the body 3.
The lock body 3 has a coned face bezel 18 `
to engage a corresponding coned seating l9 on the key body. In the front wall of the bezel a keyhole 20 is formed -comprising a central hole to receive the key bit 10 and a , pair of diametrically opposed slots 21 to receive the key ~o lugs 12 on the key bit. Further, the lock spindle 17 is ' -~
formed with a pair of diametrically opposed grooves 22 in its barrel 16 to receive the key lugs 12.
When-the door 7 is-closed the seating 19 on the key body 6 engages-the bezel 18 on the lock body 3.
The control knob 8 can then be depressed against the action of the spring 14 to insert the key bit 10 through the keyhole 20, it being guided by the locating peg 11 and the key lugs 12 passing through the slots 21 in the bezel 18 on the lock body and enyaging the grooves 22 in the barrel 16 on the lock spindle 17. Key bittings 23 are provided circumferentially between the key lugs 12 in the end of the key bit 10 (see Figure 4), and these co-operate with the pin tumblers 24 of the cylinder lock mechanism in the lock body 3 (as shown in Figure 1) to release the barrel 16 for rotation of the lock spindle by the key 9 acting through the key lugs 12 in the grooves 22. In turning the key 9 and lock spindle 17, the key lugs 12 move behind the portions of the front :
, . . ..
, ~4S~82 wall of the bezel 18 which lie between the keyhole slots 20 and which form abutment surfaces against which the key lugs engage to lock the two units 1 and 5 together.
-The lock spindle 17 is connected by a sleeve 25to a further spindle 26 which carries the cams 27,28 of each of two electrical switches 29j30, respectively.
Both switches are o~ the type in which the cam controls ~`
the position of a bridge member which serves to form a bridging connection between input and output terminals \a of the switch. The one switch 29 is connected so as to control the supply of power to the machinery being guarded and serves to connect power only when the two units 1 and 5 are locked together with the control knob 8 ~
in an ON position. From this O~ position the control -knob can be turned towards an OPEN position in which the two units 1 and 5 are unlocked, the key 3 then being disengageable from the lock body 3. Between these two positions the control knob assumes an OFF position in which the switch 29 disconnects power from the machinery ~;
being guarded but in which the two units 1 and 5 are still locked together.
The safety device therefore protects personnel against injury by preventing the connection of power to the machinery unless the door 7 is closed and locked : -- by depression and rotation of the control knob 8 to the ON position. Subse~uent unlocking of the door automatically disconnects the power. The provision of the coded bittings 23 on the key to operate the lock -tumbler mechanism makes it impossible to connect power to the unguarded machinery by insertion of a simple object through the keyhole in the lo~k body. ~:
- ' :' ::,:'',.
The safety device described so far is as disclosed ;
in our Patent No. 1 260 322. However, the present device ~ , is further modified according to the present in~ention by providing delay means which, when units 1 and 5 are Iocked together, responds to turning of the control knob from the ON to the OFF position by introducing a tlme ~ : i ' ' ~ ..... ,-. ~ ' ~':. ~.
~45~8Z
delay before the control knob can be turner further to the OPEN position.
The delay means includes a solenoid-operated plunger 31 which is mounted within the casing 2 so as to extend parallel to the lock spindle 17 and to co-operate with a cam plate 32 which is connected to the sleeve 25. When the solenoid is de-energised and the control knob 8 is in the ON and OFF positions, ; the plunger 31 is spring urged outwardly of the solenoid V so that its outer end engages in a peripheral notch 33 in the- cam plate 32 (see Figure 3). In the ON position, the plunger 31 engages one end of the notch 33 and in the OFF position the plunger 31 engages the other end of the notch, as shown in Figure 3. The plunger 31 then prevents the control knob from being turned further i to the OPEN position. The delay means further comprises ~`
the electrical switch 30 and a timer circuit 34 which is controlled by the switch 30 and which in turn controls;~
energisation of the solenoid oE plunger 31. The switch 30 ~Dis operated when the control knob reaches thè OFF position and then triggers the timer circuit 34 which in turn energises the solenoid after a predetermined time delay.
The plunger 31 is thereby withdrawn from the notch 33 in cam plate 32, whereupon the control knob can be -turned to the OPEN position and the door 7 opened.
The predetermined time delay o the timer circuit is selected so as to allow dangerous conditions in the machinery to abate before the door can be opened. i ~. :
- In an alternative embodiment of the invention, ~V the timer circuit 34 of the illustrated embodiment may be replaced by sensor means which senses the existence ~
of a potentially dangerous condition in the guarded -machinery and energises the solenoid of plunger 31 only when this condition has abated. The sensor means may be triggered by a switch, such as the switch 30, so as to operate only after the control knob 8 is turned from the ON to the OFF position. Alternatively, the sensor means may operate continuously to sense said potentially dangerous condition and to allow energisation ' ` ` ' ` , , ~ ~ . 7 .
- ` ' .
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of the solenoid only when said condition abates ~ irrespective of whether the control knob is in the I ON or OFF position.
! It will be appreciated that failure of the solenoid `. circuitry will prevent energisation of the solenoid, whereupon the control knob will be locked in the Oi~
or OFF position and the two units 1 and 5 will be locked together. The illustrated safety device is therefore "fail-safe" in design.
o- It will be further appreciated that the position of the cam plate 32 is not important and that it may be preferable to mount it on the shaft 26 on the other side of the switches 29,30 from the lock body 3~ The solenoid-operated plunger 31 would then be suitably relocated.
Further, although the illustrated embodiment is provided with a tumbler lock mechanism so as to prevent rotation of the lock spindle by insèrtion of a simple object into the keyhole, it will be appreciated that ~ -~0 this tumbler lock mechanism can be omitted either from the illustrated embodiment or any of the other embodiments described above. This does allow the possibility of rotation of the lock spindle by means other than the captive key in the key body, but this may be acceptable in some non-industrial applications, - for example in domestic appliances such as spin driers.; <~
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Claims (19)
1. A safety device comprising a first unit which is adapted for connection to a fixed structure of machinery and which includes electrical switching means for controlling power to the machinery; a second unit which is adapted for connection to a door, cover or guard and which includes manually operable keying means which is movable between successive OPEN, OFF and ON positions and is engageable with and disengageable from said first unit when in the OPEN position and co-operates with the first unit to prevent separation of the two units when engaged with the first unit and moved to the OFF and ON
positions, the keying means further controlling operation of the switching means when both units are engaged so that power is connected to the machinery only when the keying means is in the ON position; and delay means which is operative on movement of said keying means from the ON
to the OFF position and which then acts for a limited time to positively prevent movement of the keying means from the OFF to the OPEN position.
positions, the keying means further controlling operation of the switching means when both units are engaged so that power is connected to the machinery only when the keying means is in the ON position; and delay means which is operative on movement of said keying means from the ON
to the OFF position and which then acts for a limited time to positively prevent movement of the keying means from the OFF to the OPEN position.
2. A safety device as claimed in claim 1 in which the delay means comprises mechanical stop means which arrests the keying means in the OFF position and which is operated after said limited time to allow continued movement of the keying means to the OPEN position.
3. A safety device as claimed in claim 2 in which the keying means co-operates with a movable member in the first unit so as to move the movable member between corresponding OPEN, OFF and ON positions, the electrical switching means being controlled by movement of the movable member, and the stop means comprising a first stop member carried on the movable member and a second stop member which is mounted on the first unit and co-operates with said first stop member to arrest the keying means in the OFF position.
4. A safety device as claimed in claim 3 in which the keying means and movable member are rotatably mounted .9.
in the second and first units, respectively, and co-operate so as to rotate together, and in which the first stop member is fixed to the movable member so as to rotate therewith and the second stop member is mounted on the first unit so as to be movable into and out of engagement with the first stop member.
in the second and first units, respectively, and co-operate so as to rotate together, and in which the first stop member is fixed to the movable member so as to rotate therewith and the second stop member is mounted on the first unit so as to be movable into and out of engagement with the first stop member.
5. A safety device as claimed in claim 4 in which the first stop member extends substantially radially of the axis of rotation of the movable member, and the second stop member is guided to move substantially parallel to said axis of rotation of the movable member and is movable between a normal position in which it projects into the plane of movement of the first stop member so as to stop the latter in the OFF position and a release position in which it is free of the plane of movement of the first stop member.
6. A safety device as claimed in claim 2 in which the stop means is electrically operated.
7. A safety device as claimed in claim 5 in which the stop means is electrically operated and the second stop member is a solenoid operated plunger.
8. A safety device as claimed in claim 7 in which the plunger assumes the normal position when de-energised and the release position when energised.
9. A safety device as claimed in claim 3 in which the delay means further comprises timer means which is triggered when the keying means reaches said OFF
position and which, a predetermined time thereafter, operates the stop means.
position and which, a predetermined time thereafter, operates the stop means.
10. A safety device as claimed in claim 9 in which the timer means comprises an electrical timer which operates the stop means electrically.
.10.
.10.
11. A safety device as claimed in claim 9 in which the timer means comprises an electrical switch which is operated by movement of the movable member and which triggers the timer means when the keying means reaches said OFF position.
12. A safety device as claimed in claim 9 in which the timer means is part of the first unit.
13. A safety device as claimed in claim 2 in which the delay means further comprises sensor means which senses potentially dangerous conditions in the machinery and controls the stop means so that the keying means cannot be moved from the OFF to the ON position until said dangerous conditions abate.
14. A safety device as claimed in claim 4 in which the keying means is rotatably and slidably mounted in a key body which is adapted for connection to the door and carries laterally extending lugs which are insertable through corresponding slots in the first unit when the keying means is in the OPEN position and which co-operate with abutment surfaces in the first unit to prevent withdrawal of the keying means when the latter is inserted into the first unit and turned to the OFF and ON positions.
15. A safety device as claimed in claim 14 in which the lugs on the keying means engage corresponding grooves in the movable member, whereby the two are coupled to rotate together.
16. A safety device as claimed in claim 14 in which the keying means is connected to a control knob which is mounted on said key body so as to be slidable telescopically thereon and to be relative rotatably thereto.
11.
11.
17. A safety device as claimed in claim 16 in which spring means is provided in the second unit to urge the keying means to a withdrawn position relative to the key body in which the lugs thereon are automatically aligned in a predetermined angular orientation.
18. A safety device as claimed in claim 14 in which the first unit comprises a cylinder lock mechanism including a lock spindle which constitutes said movable member and which is normally locked against rotation but is freed for rotation by insertion of the keying means into said slots in the first unit.
19. A safety device as claimed in claim 18 in which the cylinder lock mechanism is of the axial pin tumbler type and in which the keying means is provided with coded bittings for engagement with the pin tumblers of the lock mechanism to effect release of the lock spindle.
.12.
.12.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1021975A GB1513823A (en) | 1975-03-12 | 1975-03-12 | Safety device for guarded machinery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1045182A true CA1045182A (en) | 1978-12-26 |
Family
ID=9963803
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA247,708A Expired CA1045182A (en) | 1975-03-12 | 1976-03-11 | Safety device for guarded machinery |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS5943680B2 (en) |
| CA (1) | CA1045182A (en) |
| CH (1) | CH625027A5 (en) |
| DE (1) | DE2609537A1 (en) |
| FR (1) | FR2303928A1 (en) |
| GB (1) | GB1513823A (en) |
| IT (1) | IT1056953B (en) |
| NL (1) | NL7602509A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58501548A (en) * | 1981-09-10 | 1983-09-16 | スミス，ドナルド・ベビントン | Fixed and controlled motion devices |
| US5011199A (en) * | 1989-12-28 | 1991-04-30 | Von Duprin, Inc. | Panic exit device having an exit-delaying mechanism |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2325406A (en) * | 1941-07-12 | 1943-07-27 | American Laundry Mach Co | Cover lock and extractor control |
| GB1260322A (en) * | 1969-09-30 | 1972-01-12 | Gregory Frank Whiteley | Improvements in and relating to a safety device for guarded machinery |
| GB1350911A (en) * | 1970-07-03 | 1974-04-24 | British Domestic Appliances | Washing and like clothes or fabric treating machines |
| BE791863A (en) * | 1971-11-26 | 1973-03-16 | Rocchitelli Onofrio | DEVICE FOR TIMED LOCKING AND UNLOCKING OF MACHINE DOOR CLOSING DEVICES |
| DE2329964C3 (en) * | 1973-06-13 | 1975-12-11 | Condux-Werk, Herbert A. Merges Kg, 6451 Wolfgang | Electromechanical safety interlock device |
-
1975
- 1975-03-12 GB GB1021975A patent/GB1513823A/en not_active Expired
-
1976
- 1976-03-08 DE DE19762609537 patent/DE2609537A1/en not_active Withdrawn
- 1976-03-09 IT IT2097876A patent/IT1056953B/en active
- 1976-03-10 NL NL7602509A patent/NL7602509A/en unknown
- 1976-03-11 CA CA247,708A patent/CA1045182A/en not_active Expired
- 1976-03-11 FR FR7606910A patent/FR2303928A1/en active Granted
- 1976-03-11 CH CH305776A patent/CH625027A5/en not_active IP Right Cessation
- 1976-03-12 JP JP2700876A patent/JPS5943680B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2303928B1 (en) | 1982-11-19 |
| FR2303928A1 (en) | 1976-10-08 |
| GB1513823A (en) | 1978-06-14 |
| CH625027A5 (en) | 1981-08-31 |
| JPS5943680B2 (en) | 1984-10-23 |
| DE2609537A1 (en) | 1976-09-30 |
| JPS51145979A (en) | 1976-12-15 |
| IT1056953B (en) | 1982-02-20 |
| NL7602509A (en) | 1976-09-14 |
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