CA1337706C - Food heating safety device - Google Patents
Food heating safety deviceInfo
- Publication number
- CA1337706C CA1337706C CA 586350 CA586350A CA1337706C CA 1337706 C CA1337706 C CA 1337706C CA 586350 CA586350 CA 586350 CA 586350 A CA586350 A CA 586350A CA 1337706 C CA1337706 C CA 1337706C
- Authority
- CA
- Canada
- Prior art keywords
- safety device
- food
- power supply
- activation
- switch
- 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 - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H5/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection
Landscapes
- Electric Stoves And Ranges (AREA)
Abstract
There is disclosed a safety device for shutting off the power supply to a food heating appliance, typically a stove or range, or detection of a condition, such as smoke, indicative of burning food. The device includes a switch for location in the power supply circuit between the power supply source and a range, a sensor such as a smoke detector for location n the vicinity of the appliance for activation when smoke is detected, and an actuator for opening the switch on activation of the smoke detector. If food begins to burn on the stove, this activates the smoke detector which in turn causes the actuator to open the switch and shut off the power supply to the range. This stops or at least reduces the heating action of the range to prevent further burning of the food.
Description
~ -2- 1 3 3 7 7 0 6 SAFETY DEVICE
This invention relates to a safety device. The invention has particular application in the control of the power supply to a range or other food heating appliance.
When cooking a meal or a dish, cooks will often leave a stove unattended while food is being heated in or on the stove. In normal circumstances the cook will return to the stove periodically, for example to remove a pan from a hot-plate, or to change a settin~ on an oven. However, occasionally the stove will be left unattended for an unintentionally longer period of time or, for example, a pan may be overfilled or placed on a hot-plate that is set too high. In such circumstances the food being heated may burn or overflow from its containing dish or pan. If this continues for a short time, the food is spoiled and some damage to the containing dish or pan may result. Over a longer period, the smoke and fumes from the burning food and container may result in smoke damage and may even present a danger to health. The stove may also suffer serious damage.
Overheating of some cooking material, for example cooking oil, may result in a serious risk of fire.
_ -3- 1 337706 According to the present invent:ion, there is provided a safety device for shutting off the power supply to a food heating appliance on detection of a condition indicative of burning food. The device includes switch means for location in the power supply circuit of a food heating appliance between the power supply source and the appliance, sensor means for location in the vicinity of the appliance for activation when a condition indicative of burning food is detected, and actuator means for opening said switch means on activation of said sensor means.
If food begins to burn on the appliance, this activates the sensor means which in turn causes the actuator means to open the switch means and shut off the power supply to the appliance. This stops or at least reduces the heating action of the appliance to prevent further burning of the food. Preferably, the sensor means produces a warning signal on activation, and this may continue after the appliance has been shut off.
Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Fig. 1 is a schematic representation of a safety device of a first embodiment of the present invention; and -_4_ 1 3 3 7 7 0 6 Fig. 2 is a schematic representation of a safety device of a second embodiment of the present invention.
Reference is first made to Fig. 1 of the drawings, which illustrates, in schematic form, a safety device 10 in accordance with a first embodiment of the present invention.
The device 10 is intended to shut off the electricity supply from the mains (not shown), incoming through plug 12, to an electrical food heating appliance such as range 14. When a condition indicative of burning food is detected in the vicinity of the range 14, activation of sensor means results in the actuation of various relays and the opening of switch means between the range 14 and the mains supply. In this embodiment sensor means in the form of a smoke detector 16 is provided to detect the presence of smoke.
The smoke detector 16 is mounted, for example, on the ceiling of the kitchen in which the range 14 is located. To avoid having the detector set of by the steam and small amount of smoke which may be produced by normal cooking, the detector should be mounted away from the range 14 such that it will only detect the relatively large amounts of smoke produced by burning food.
The detector 16 is powered by a 9V battery 18 and includes a sensor/switch 20 and an audible signal producing horn 22. On 1 3377~6 detecting smoke, the switch is closed and the horn 22 sounds.
It will be seen that leads 24 and 26 are connected to the contacts 23 of horn 22. Leads 24, 26 extend from the detector to a relay coil 28. Coil 28 forms part of a switch actuating means 30 which controls the electricity supply to the range 14.
The switch actuating means 30 includes an external plug connector 12, for insertion into mains supply sockets (not shown), and leads 31 connected to a socket 32. The plug connector 33 of the range 14 is plugged into socket 32. The unit further includes two relays. The first relay comprises the coil 28 which is energized on activation of the smoke detector 16. Associated with coil 28 is a normally open connection 28-1. It should be noted that the drawings show detached contact notation, in which a cross represents a normally open connection and a single line represents a normally closed connection.
When the coil 28 is energized the contact 28-1 is closed.
This energizes a second coil 34 forming part of a llOV
relay, which is powered directly from the mains supply through a suitable rectifier 33a. This second relay serves in effect only to provide a step-up of power from the first ; -6 1 33770~
9V relay, as the coil 28 would not be capable of opening therelatively heavy connections between the mains supply and the range, shown as 34-1 and 34-2. Since the illustrated range operates at 220V and the mains supply is two-phase llOV, two live leads 31a, 31b and a neutral lead 31c are provided.
Relay coil 34 when energized opens two normally closed contacts 34-1, 34-2, one in each lead 31a, 31c respectively.
(There is no need to open the neutral lead 31c.) Thus, it will be seen that detection of smoke by the detector results in the energising of coils 28 and 34 and the shutting-off of the electrical supply to the range 14.
If desired, relay 34 can have a normally open contact 34-3 in parallel with contact 28-1. Then, once relay 34 turns on, contact 34-3 closes and locks relay 34 on, keeping the range 14 turned off until a reset button 40 is pushed to open the circuit. Reset button 40 is spring biased to a normally closed condition. For testing the detector 16 without cutting off the electrical supply to the range 14, a switch 36 may be provided in the detector 16 to isolate the coil 28.
Reference is now made to Fig. 2 of the drawings, which _ I 337706 illustrates, in schematic form, a safety device 50 in accordance with a second embodiment of the present invention. As with the device lO described above, this device 50 is intended to shut off the electricity supply from the mains (not shown), incoming through plug 52, to an electrical food heating appliance such as range 54 when a condition indicative of food burning is detected in the vicinity of the range 54. However, in this device there is no direct wiring link between the sensor means, again in the form of a smoke detector 56, and the switch actuating means.
This allows the device to be installed without the requirement for wires or leads trailing between the detector 56 and the unit 58 containing the switch actuating means.
When smoke is produced the smoke detector 56 is activated and produces an audible alarm, indi.cated by lines 60. This sound is detected by the unit 58 which then shuts off the electricity supply to the range 54. It will be seen that the unit 58 includes a microphone 62 linked to a receiver/
amplifi.er 64, from which a s-gnal is passed to an adjustable comparator 66. If the sound picked up by the microphone 62 is above an adjustable predetermined level, say 90db, a signal is passed to a timer 68. If the signal from the comparator is present for an adjustable predetermined time, say lO seconds, the timer 68 energizes and locks on a coil 70 of a rel-ay, to shut-off power to the range 54. The use of the comparator 66 and timer 68 help to prevent accidental activation of the relay, because only loud noises, sustained for a length of time, such as would normally only be produced by the detector 54, will trigger the unit 58.
The relay in the unit 58 includes three normally closed connections 70-1, 70-2 and /0-3, which control the supply of electricity from the llOV mains supply to the 220V range 54.
Activation of the coil 70 opens the connections 70-1, 70-2 and 70-3, thus turning off the range 54. The unit may be reset using reset switch 72 (which is normally spring biased to a closed condition).
It will be clear to those skilled in the art that the above embodiments are merely exemplary and that, for example, the relays used may operate in the opposite manner from those described above. Also, the invention is not limited to use with electric ranges, and could also be used with other appliances such as deep fat fryers and toasters. Also, devices of different configurations could be used with gas ranges, where the supply of gas to the range could be shut off by closing a valve between the gas main and the range.
This invention relates to a safety device. The invention has particular application in the control of the power supply to a range or other food heating appliance.
When cooking a meal or a dish, cooks will often leave a stove unattended while food is being heated in or on the stove. In normal circumstances the cook will return to the stove periodically, for example to remove a pan from a hot-plate, or to change a settin~ on an oven. However, occasionally the stove will be left unattended for an unintentionally longer period of time or, for example, a pan may be overfilled or placed on a hot-plate that is set too high. In such circumstances the food being heated may burn or overflow from its containing dish or pan. If this continues for a short time, the food is spoiled and some damage to the containing dish or pan may result. Over a longer period, the smoke and fumes from the burning food and container may result in smoke damage and may even present a danger to health. The stove may also suffer serious damage.
Overheating of some cooking material, for example cooking oil, may result in a serious risk of fire.
_ -3- 1 337706 According to the present invent:ion, there is provided a safety device for shutting off the power supply to a food heating appliance on detection of a condition indicative of burning food. The device includes switch means for location in the power supply circuit of a food heating appliance between the power supply source and the appliance, sensor means for location in the vicinity of the appliance for activation when a condition indicative of burning food is detected, and actuator means for opening said switch means on activation of said sensor means.
If food begins to burn on the appliance, this activates the sensor means which in turn causes the actuator means to open the switch means and shut off the power supply to the appliance. This stops or at least reduces the heating action of the appliance to prevent further burning of the food. Preferably, the sensor means produces a warning signal on activation, and this may continue after the appliance has been shut off.
Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Fig. 1 is a schematic representation of a safety device of a first embodiment of the present invention; and -_4_ 1 3 3 7 7 0 6 Fig. 2 is a schematic representation of a safety device of a second embodiment of the present invention.
Reference is first made to Fig. 1 of the drawings, which illustrates, in schematic form, a safety device 10 in accordance with a first embodiment of the present invention.
The device 10 is intended to shut off the electricity supply from the mains (not shown), incoming through plug 12, to an electrical food heating appliance such as range 14. When a condition indicative of burning food is detected in the vicinity of the range 14, activation of sensor means results in the actuation of various relays and the opening of switch means between the range 14 and the mains supply. In this embodiment sensor means in the form of a smoke detector 16 is provided to detect the presence of smoke.
The smoke detector 16 is mounted, for example, on the ceiling of the kitchen in which the range 14 is located. To avoid having the detector set of by the steam and small amount of smoke which may be produced by normal cooking, the detector should be mounted away from the range 14 such that it will only detect the relatively large amounts of smoke produced by burning food.
The detector 16 is powered by a 9V battery 18 and includes a sensor/switch 20 and an audible signal producing horn 22. On 1 3377~6 detecting smoke, the switch is closed and the horn 22 sounds.
It will be seen that leads 24 and 26 are connected to the contacts 23 of horn 22. Leads 24, 26 extend from the detector to a relay coil 28. Coil 28 forms part of a switch actuating means 30 which controls the electricity supply to the range 14.
The switch actuating means 30 includes an external plug connector 12, for insertion into mains supply sockets (not shown), and leads 31 connected to a socket 32. The plug connector 33 of the range 14 is plugged into socket 32. The unit further includes two relays. The first relay comprises the coil 28 which is energized on activation of the smoke detector 16. Associated with coil 28 is a normally open connection 28-1. It should be noted that the drawings show detached contact notation, in which a cross represents a normally open connection and a single line represents a normally closed connection.
When the coil 28 is energized the contact 28-1 is closed.
This energizes a second coil 34 forming part of a llOV
relay, which is powered directly from the mains supply through a suitable rectifier 33a. This second relay serves in effect only to provide a step-up of power from the first ; -6 1 33770~
9V relay, as the coil 28 would not be capable of opening therelatively heavy connections between the mains supply and the range, shown as 34-1 and 34-2. Since the illustrated range operates at 220V and the mains supply is two-phase llOV, two live leads 31a, 31b and a neutral lead 31c are provided.
Relay coil 34 when energized opens two normally closed contacts 34-1, 34-2, one in each lead 31a, 31c respectively.
(There is no need to open the neutral lead 31c.) Thus, it will be seen that detection of smoke by the detector results in the energising of coils 28 and 34 and the shutting-off of the electrical supply to the range 14.
If desired, relay 34 can have a normally open contact 34-3 in parallel with contact 28-1. Then, once relay 34 turns on, contact 34-3 closes and locks relay 34 on, keeping the range 14 turned off until a reset button 40 is pushed to open the circuit. Reset button 40 is spring biased to a normally closed condition. For testing the detector 16 without cutting off the electrical supply to the range 14, a switch 36 may be provided in the detector 16 to isolate the coil 28.
Reference is now made to Fig. 2 of the drawings, which _ I 337706 illustrates, in schematic form, a safety device 50 in accordance with a second embodiment of the present invention. As with the device lO described above, this device 50 is intended to shut off the electricity supply from the mains (not shown), incoming through plug 52, to an electrical food heating appliance such as range 54 when a condition indicative of food burning is detected in the vicinity of the range 54. However, in this device there is no direct wiring link between the sensor means, again in the form of a smoke detector 56, and the switch actuating means.
This allows the device to be installed without the requirement for wires or leads trailing between the detector 56 and the unit 58 containing the switch actuating means.
When smoke is produced the smoke detector 56 is activated and produces an audible alarm, indi.cated by lines 60. This sound is detected by the unit 58 which then shuts off the electricity supply to the range 54. It will be seen that the unit 58 includes a microphone 62 linked to a receiver/
amplifi.er 64, from which a s-gnal is passed to an adjustable comparator 66. If the sound picked up by the microphone 62 is above an adjustable predetermined level, say 90db, a signal is passed to a timer 68. If the signal from the comparator is present for an adjustable predetermined time, say lO seconds, the timer 68 energizes and locks on a coil 70 of a rel-ay, to shut-off power to the range 54. The use of the comparator 66 and timer 68 help to prevent accidental activation of the relay, because only loud noises, sustained for a length of time, such as would normally only be produced by the detector 54, will trigger the unit 58.
The relay in the unit 58 includes three normally closed connections 70-1, 70-2 and /0-3, which control the supply of electricity from the llOV mains supply to the 220V range 54.
Activation of the coil 70 opens the connections 70-1, 70-2 and 70-3, thus turning off the range 54. The unit may be reset using reset switch 72 (which is normally spring biased to a closed condition).
It will be clear to those skilled in the art that the above embodiments are merely exemplary and that, for example, the relays used may operate in the opposite manner from those described above. Also, the invention is not limited to use with electric ranges, and could also be used with other appliances such as deep fat fryers and toasters. Also, devices of different configurations could be used with gas ranges, where the supply of gas to the range could be shut off by closing a valve between the gas main and the range.
Claims (7)
1. A safety device for shutting off the power supply to a food heating appliance on detection of a condition indicative of burning food comprising: switch means for location in the power supply circuit of a food heating appliance between the power supply source and the appliance;
first sensor means for location in the vicinity of the food heating appliance for activation when a condition indicative of burning food is detected; and actuator means connected to said first sensor means and responsive to activation thereof for opening said switch means on activation of said first sensor means.
first sensor means for location in the vicinity of the food heating appliance for activation when a condition indicative of burning food is detected; and actuator means connected to said first sensor means and responsive to activation thereof for opening said switch means on activation of said first sensor means.
2. A safety device as claimed in claim 1, in which the sensor means comprises a smoke detector.
3. A safety device as claimed in claim 2, in which the actuator means and switch means comprises a relay for controlling the power supply to the appliance.
4. A safety device as claimed in claim 3, in which said actuator means comprises switch means for connection to said smoke detector and adapted to be powered by the battery thereof, said relay being connected to said switch means for operation upon operation of said switch means.
5. A safety device as claimed in claim 2, in which the actuator means includes sound sensor means for detecting the activation of said first sensor means and opens said switch means on detecting activation of said smoke detector.
6. A safety device as claimed in claim 5, in which said actuator means includes circuit means connected to said sound sensor means for sensing when the sound detected is above a predetermined level and is maintained for a predetermined length of time, and for thereupon opening said switch means.
7. A safety device as claimed in claim 5, in which said circuit means is adjustable to set said level and said length of time.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 586350 CA1337706C (en) | 1988-12-19 | 1988-12-19 | Food heating safety device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 586350 CA1337706C (en) | 1988-12-19 | 1988-12-19 | Food heating safety device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1337706C true CA1337706C (en) | 1995-12-05 |
Family
ID=4139319
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 586350 Expired - Fee Related CA1337706C (en) | 1988-12-19 | 1988-12-19 | Food heating safety device |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1337706C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8068034B2 (en) | 2007-11-14 | 2011-11-29 | Pioneering Technology Corp. | Safety sensor device |
-
1988
- 1988-12-19 CA CA 586350 patent/CA1337706C/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8068034B2 (en) | 2007-11-14 | 2011-11-29 | Pioneering Technology Corp. | Safety sensor device |
| US8604935B2 (en) | 2007-11-14 | 2013-12-10 | Pioneering Technology Corp. | Safety sensor device |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |