Abstract:
A ventilation or exhaust system, having ducting, and a fan assembly for placement in ducting of a ventilation or exhaust system for an environment space. The fan assembly has a motor having an output shaft, a fan mounted on the output shaft, and a brake mounted for operation on the motor. The brake is operable for stopping rotation of the motor upon a detection of a prescribed situation one or more of: the environmental space, and the ducting. Also included is a valve assembly having a valve member for placement in the ducting for movement between a first position where the ducting is substantially open, and a second position where the ducting is substantially closed. The valve member is adapted to move from the first position to the second position in response to at least one detection of a prescribed situation. At least one detector is provided for detecting a prescribed situation, the detector being for controlling the operation of the brake of the fan assembly, and the valve assembly, in response to the detecting.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to controls for ventilation and exhaust ducts and fans and preferably, through not exclusively, relates to such an apparatus for use in offices, commercial kitchens, factories, warehouses, retail centres, production facilities, car parks, cooling tower fans, or the like. 
       BACKGROUND OF THE INVENTION 
       [0002]    Exhaust apparatus for fumes and/or smoke are normally used in commercial kitchens, factories, production facilities, car parks, cooling tower fans or the like, to exhaust fumes and/or smoke and/or gasses caused by the cooking or production process, or vehicle exhausts. Some exhaust systems may have a hood above the stove or production facility, and ducting to connect the hood to the outside atmosphere. One or more fans are built into the ducting or the hood to force the fumes and/or smoke through the ducting. Filters may be used to remove the principal contaminants from the fumes and/or smoke. 
         [0003]    The fan or fans are normally controlled by a control panel. If a hood is used, it may be on the front of the hood. The fan may be multi-speed with corresponding speed controls on the control panel. This means the fans may not be on when required, may be on when not required or may be operated at a speed in excess of that required, or may be operated at a speed less than that required. Such a situation can lead to ineffective or inefficient fume and/or smoke extraction, and/or excess use of the fan and therefore increased power consumption. Increased power consumption leads to increased energy costs. For example, in many commercial kitchens exhaust fans are operated at full speed from the beginning of food preparation until the last dish is cleaned. Also, in car parks they operate continually at full speed even when there is no vehicle movement in operation. Such a level of use is very wasteful of energy and increases operational costs. 
         [0004]    There have been proposed exhaust systems that monitor the ambient temperature in the kitchen. Such systems do not operate in the presence of noxious gasses or fumes, or when the carbon dioxide and/or carbon monoxide level increases and the oxygen level decreases in the ambient air. Also, there is a tendency for the ducting to act as a conduit for fire if the premises are on fire, or for contaminants in the ducting to catch fire. Ducting for exhaust systems does not normally deal with such problems and can enhance the fire by the fan(s) being on, and the ducting being open to the outside atmosphere. 
         [0005]    Also, ventilation systems for supplying air to zoned structures such as offices, warehouses and retail centres rely on fire detectors adjacent the zone boundary. At the zone boundary there are dampers in the duct. Upon the fire detector operating, the damper is operated to reduce the risk of fire spread. But by then the fire is close to penetrating the boundary. Also each damper operates independently and there is no structured approach to use and operation of the dampers, and duct fans, for prevention of the spread of fire. Often the only source of air to fuel the fire is the ventilation duct. Therefore, closing the duct and braking the fan to a complete stop as early as possible can slow the fire considerably by removing the source of oxygen. 
       SUMMARY OF THE INVENTION 
       [0006]    In accordance with a first preferred aspect there is provided a fan assembly for placement in ducting of a ventilation or exhaust system for an environmental space, the fan assembly comprising:
       (a) a motor having an output shaft;   (b) a fan mounted on the output shaft; and   (c) a brake for operation on the motor
 
wherein
   (d) the brake is operable for stopping operation of the motor upon a detection of a prescribed situation in one or more of: the environmental space, and the ducting.       
 
         [0011]    In accordance with a second preferred aspect there is provided a valve assembly for placement in ducting of a ventilation or exhaust system, the valve assembly comprising:
       (a) a valve member for placement in the ducting for movement between a first position where the ducting is substantially open; and a second position where the valve member substantially closes the exhaust ducting;   (b) the valve member being adapted to move from the first position to the second position in response to at least detection of a prescribed situation. The valve member may mounted on a spindle for movement therewith between the first and second positions; the spindle being for operative connection to a drive motor for movement of the spindle for causing the valve member to move between the first and second positions.       
 
         [0014]    The prescribed situation may be the detecting of the presence of at least one: heat, fire, smoke, fumes, gas, and obnoxious fumes. The gas may be one or more of: a cooking gas, carbon monoxide, and carbon dioxide. 
         [0015]    The valve member may be sized and shaped to substantially accord to an interior size and shape of the exhaust ducting. 
         [0016]    In accordance with a third preferred aspect there is provided a ventilation or exhaust system comprising:
       (a) ducting;   (b) the fan assembly described above;   (c) the valve assembly described above; and   (d) at least one detector for detecting a prescribed situation and for controlling the operation of:
           (i) the brake of the fan assembly, and   (ii) the valve assembly
 
in response to the detecting.
   
               
 
         [0023]    The valve assembly may be located at, adjacent or near an outlet end of the ducting or at a boundary of zones of the environmental space. The exhaust apparatus may further comprise a hood, the hood having a control panel. The control panel may comprise a reset control for resetting the at least one detector, releasing the brake of the fan assembly, and moving the valve member to the first position. The exhaust apparatus may further comprise at least one sensor for controlling the operation of the fan assembly. The at least one sensor may be at least one of a time sensor, a gas sensor, and at least one heat sensor. The at least one sensor may be arranged in groups. There may be a plurality of sensors, a plurality of groups, and a plurality of sensors in each group. The number of sensors, or number of groups of sensors, activated may determine the speed of operation of the fan. For a time sensor, the time stage may determine the speed of operation of the fan. 
         [0024]    In accordance with a fourth preferred aspect there is provided a ventilation or exhaust system comprising:
       (a) a fan assembly as described above; and   (b) a plurality of sensors for automatically controlling the operation of the fan assembly by controlling the operational speed of the fan assembly in accordance with the number, location or nature of sensors that are activated.       
 
         [0027]    The system may further comprise:
       (c) a master on control for overriding the time sensor;   (d) a master off control for overriding the time sensor; and   (e) time controls for setting the first and second preset times.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]    In order that the present invention may be fully understood and readily put into practical effect, there shall now be described by way of non-limitative example only preferred embodiments of the present invention, the description being with reference to the accompanying Illustrative drawings. 
           [0032]    In the drawings: 
           [0033]      FIG. 1  is a front perspective view of a preferred embodiment; 
           [0034]      FIG. 2  is a vertical cross-sectional view of the embodiment of  FIG. 1 ; 
           [0035]      FIG. 3  is an enlarged view of one embodiment the fan assembly of  FIG. 2 ; 
           [0036]      FIG. 4  is block diagram of an alternative embodiment for the fan assembly; 
           [0037]      FIG. 5  is an enlarged view of the duct valve of  FIG. 2  when in the open position; 
           [0038]      FIG. 6  is an enlarged view of the duct valve of  FIG. 2  in the closed position; 
           [0039]      FIG. 7  is a vertical cross-sectional view of an alternative duct value in the open position; 
           [0040]      FIG. 8  is a view corresponding to  FIG. 7  in the closed position; 
           [0041]      FIG. 9  is an enlarged view of the part of the stove and hood of  FIG. 2  illustrating the sensor arrangement; 
           [0042]      FIG. 10  is a block diagram of a first sensor array; 
           [0043]      FIG. 11  is a flow chart for the operation of the embodiment of  FIG. 10 ; 
           [0044]      FIG. 12  is a flow chart for the operation of the embodiment of  FIG. 10  with timing sensors, and 
           [0045]      FIG. 13  is an illustration of a zone system for fire and other control. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0046]    To refer to  FIGS. 1 and 2 , there is illustrated a commercial stove  10  with an exhaust hood  12 . Ducting  14  connects the exhaust hood  12  to the outside atmosphere  16 . Although a stove  10  is shown, it could be any commercial or industrial equipment that produces or uses smoke and/or fumes and/or noxious gasses, a car park for removing vehicle exhaust fumes, and so forth. 
         [0047]    The stove  10  has hobs  18  for use in the cooking of food, and are or more ovens  20  also used in the cooking of food. 
         [0048]    The exhaust hood  12  has a control panel  22  for controlling the operation of the exhaust hood  12 , including the operation of a fan assembly  24 . Although a single fan assembly  24  is shown, there may be two or more fan assemblies. The fan assembly  24  may be of any suitable form or nature. Preferably, the fan assembly  24  is multiple speed. 
         [0049]    Also in ducting  14  is a valve  26  that is shown in the open position in  FIG. 2 , and which is adjacent the outlet end  28  of the ducting  14 . The outlet end  28  is in the outside and is therefore outside the premises in which stove  10 , hood  12  and ducting  14  are located. The outlet end  28  may have a weather cap  30 , if required or desired. Valve  26  may be at any location in ducting  14 . There may be more than one valve  26  in ducting  14 . If ducting  14  is zones, there may be a valve  26  for each zone. 
         [0050]    One form of the fan assembly  24  is shown in more detail in  FIG. 3 . The fan assembly  24  may have a shroud  32 . The shroud  32  may be spaced from ducting  14 , or may be a relatively sealing fit in ducting  14 . Non-rotatably mounted within shroud  32  is a drive motor  34  with an output shaft  36 . Mounted on output shaft  36  is a fan  38 . Motor  34  and fan may be within the shroud  32 . Motor  34  is powered by an electric supply cable  40  for rotating shaft  36  and thus fan  38 . 
         [0051]    Mounted for acting on shaft  36  is a brake  42 . Brake  42  is secured to the motor  34  and/or shroud  32  so that it does not rotate relative thereto. Shaft  42  rotates relative to brake  42 . 
         [0052]    When a prescribed situation such as, for examples, smoke, fumes or heat above a preset density or level is detected in ducting  14  by one or more of smoke, fume or heat detectors  44 ,  46 , and if the motor  34  is on, the motor  34  is immediately switched off and brake  42  applied so that the motor  34  and shaft  36 , and thus fan  38 , will stop rotating in the shortest possible time. This prevents or stops air flow in ducting  14  due to fan assembly  24 . Furthermore, as the air is moving in ducting  14  the air will have momentum. By use of the brake  42 , the fan  38  is held stationary. As such, the fan  38  becomes a damper on the movements of air within ducting  14  and this air movement ceases far more speedily if brake  42  is not applied, the shaft  36  and thus fan  38  would continue to rotate at a decreasing rate, the rate of decrease depending on function within motor  34 , the inertia of the fan  38  and the momentum of the air flow in ducting  14  over fan assembly  24 . Further, by use of brake  42  the generation of a back EMF by motor  34  is minimized. 
         [0053]    The motor  34  and brake  42  are operatively connected to detectors  44 ,  46  by a wiring loom  48 . The detectors  44 ,  46  may have the same, or different, preset smoke, fume or heat density or other levels. The motor  34  and brake  42  may also be connected to a fire alarm system, so that upon the fire alarm being activated, motor  34  is switched off and brake  42  applied. 
         [0054]    An alternative is shown in  FIG. 4  where in place of the physical brake  42  there is a variable speed drive  43  for the motor  34  to enable motor  34  to have a number of speeds of operation. The variable speed drive  34  includes an electric brake component that operates electrically to stop motor  34 . The variable speed drive  43  may be at the motor  34 , or may be remote from the motor  34 . 
         [0055]    Also operatively connected to smoke fume or heat detectors  44 ,  46  by cable loom  48  is a duct valve  26  located in the ducting  14 . The valve  26  may be anywhere in the ducting  14 . As shown, it is at, adjacent or near the outer end  28  of ducting  14 . There may be more than one valve  26  in ducting  14 . If ducting  14  is in zones, there may be a valve  26  for each zone, preferably at the boundary of each zone. 
         [0056]    The valve  26  is shown in the open position in  FIGS. 2 and 5 , and in the closed position in  FIG. 6 . Upon either or both of the smoke detectors  44 ,  46  operating as described above, a step motor  50  operates to rotate a spindle  52  by 90° so that a valve member  54  is also rotated by 90° from the open position ( FIGS. 2 and 5 ) to the dosed position ( FIG. 6 ). Valve member  54  is mounted on spindle  52  to rotate therewith. The valve member  54  may almost, or substantially, seal the ducting  14  to create static pressure within the ducting  14 , and thus to prevent the passage to the outlet end  28  of smoke, fumes or the like. By having the valve member at, adjacent or near the outlet end  28 , any smoke, fumes or the like generated anywhere in ducting  14  will be prevented from passing through outlet end  28 . 
         [0057]    The valve member  54  will be sized and shaped to substantially accord to the internal size and shape of the ducting  14 . Thus, if ducting  14  is of a circular cross-sectional shape, the valve member  54  will be circular (as shown) and of substantially the same radius. If the ducting  14  is of a square cross-sectional shape, the valve member  54  will also be square and of substantially the same side length. 
         [0058]    In this way, upon an excessive level of smoke or fumes in ducting  14  being detected by either or both detectors  44 ,  46 , valve  26  operates to close the outlet end  28  of the ducting  14 ; and motor  34  is switched off and brake  42  or  43  applied to prevent rotation of fan  38 . This prevents, or minimizes, movement of the smoke or fumes within the ducting  14 , and can prevent contamination of the outside atmosphere  16  if the smoke or fumes are of a polluting or toxic nature. 
         [0059]    As shown in  FIG. 13 , there may be two ducts  14  and  214  for supplying or exhausting air to or from outlets  80  and  280  in a zone  82  of a building. Air supply may be conditioned air. The zone  82  is defined by zone boundary walls  84 . Duct valves  86  and  286  are located in ducts  14 ,  214  respectively. A number of sensors and detectors  44  are located in zone  82  and/or ducts  14 ,  214  for detecting a prescribed situation in zone  82  and/or ducts  14 ,  214 . The prescribed situation may be the presence of one or more of: smoke, fumes, gas, heat, noxious fumes, and fire. The gas may be of any form including a cooking gas, carbon dioxide and a carbon monoxide. Valves  14 ,  214  operate as described above if any one of the sensors or detectors  44  is activated. This isolates zone  82  as early as possible so that any fire in zone  82  is starved of oxygen and will thus spread at a slower rate. Similarly, valves  86 ,  286  may also be linked to and operated by the building fire alarm to prevent the spread of smoke or fumes even if the prescribed situation is not in zone  82 . 
         [0060]    The control panel  22  may include a ‘reset’ button or switch  56  if required or desired to enable the valve  26  to return to the open position ( FIGS. 2 and 4 ), for brake  42  to be released and motor  34  switched on, and for resetting the detectors  44 ,  46 . 
         [0061]      FIGS. 7 and 8  show an alternative form of valve  26 . Here, the valve member  55  comprises a number of portions  57  hingedly connected together and being biased to the closed position. A stop  59  holds them in the open position against the bias. An electromagnetic motor  51  is used to release the stop  59  to close the duct  14 , and to subsequently reopen the duct  14 . 
         [0062]    In  FIGS. 9 and 10 , there is shown a number of possible sensor arrangement for enabling the automatic operative of the fan assembly  24 . 
         [0063]    In  FIG. 9 , there are three possible sensors  58 ,  60 ,  62  operatively connected to fan assembly  24  by wiring loom  48  and control box  68  that contains all necessary control functionality (including relays, and so forth) for the valve assembly  26 , fan assembly  24 , control panel  22 , and the sensors/detectors  44 ,  46 ,  58   60  and  62 . 
         [0064]    Sensor  58  is one or more sensors for heat or temperature, but preferably heat, and located at, on or adjacent hobs  18  so that upon one or more of the hobs  18  being operated to generate heat for cooking, the sensor  58  will operate to switch on fan assembly  24 . Upon the heat ceasing, sensor  58  will operate to switch off the fan assembly  24 . This may cause repeated, short cycles of operation. As the largest consumption of electricity by fan assembly  24  is at start-up, although this system is effective it may not be electrically efficient. However, this may be applicable for car parks where a combination of heat from engines and exhausts or exhaust fumes may be detected. Also, or alternatively, a time-based system may be utilized to cover peak operational periods. 
         [0065]    Sensor  60  is somewhat similar to sensor(s)  58  but is located in the hood  12  so that it detects heat from hobs  18 . This may reduce the number of sensors required, but may suffer the same problem. 
         [0066]    Sensor  62  is a time sensor. With commercial kitchens, and many industrial processors, the period of peak operation is known. For example, a restaurant that is open for lunch from midday to 3 pm will have the kitchen preparing foods by cooking from about 11.00 am, and will be cooking until about 2.00 pm. Therefore, the fan assembly  24  needs to operate from 11.00 am to 2.00 pm only. Therefore, time sensor  60  will automatically switch on the fan assembly  24  at 11.00 am, and automatically switch if off at 2.00 pm. The control panel  22  may contain time adjusting knobs  64  for adjusting the on and off times. Within the time period 11.00 am to 2.00 pm, the operating speed of the fan assembly  24  may vary. As shown in  FIG. 12 , at the beginning of operation the fan  28  may be at a first preset speed in the range 25% to 75%, preferably 50%; at a second stage in the timing at a second preset speed in the range 75% to 100%, preferably 80%; and at a third stage at a third speed being full speed. 
         [0067]    A further sensor  74  may be provided for sensing a prescribed situation in the interior or environmental space (such as zone  82 ). The prescribed situation may be the presence of one or more of: smoke, fumes, gas, heat, noxious fumes, and fire. The gas may be of any form including a cooking gas, carbon dioxide and a carbon monoxide. 
         [0068]    The control panel  22  may also have a master on switch  66  for manually switching on the fan assembly  24  irrespective of the time or temperature, and a master off switch  66  for manually switching off the fan assembly  24  irrespective of the time or temperature. 
         [0069]    Two or more of the sensors  58 ,  60 ,  62  may be provided and may be connected in series so that the fan assembly  24  will only, operate when all the sensors are active; or in parallel so that the fan assembly will operate when any one or more of the sensors is active. 
         [0070]      FIG. 10  shows multiple sensors  58  on hobs  18 , each hob having a pot support  64 . Here the smallest hob  66  has one sensor  58 ; the small, intermediate hob  68  has two sensors; the two larger, intermediate hob  70  has two sensors  58 ; and the largest hob  72  has four sensors  58 . However, each hob  66 ,  68 ,  70  and  72  may have the same number of sensors  58 , if required. 
         [0071]    As is shown in  FIG. 11 , the fan  28  is preset to start at a predetermined speed when first operational. That may be in the range of 25% to 75%, preferably 50%. When a sensor  58  is activated it determines if one or more sensors  58  have been activated. The sensors  58  may be arranged in groups, if desired. If one sensor  58 , or one group of sensors  58 , is activated, the fan speed is increased to a second predetermined speed that may be in the range 60% to 80%, preferably 70%. If a second sensor  58 , or a second group of sensors  58 , is activated the fan speed is increased to a third predetermined speed in the range 75% to 95%, preferably 85%. If all sensors  58 , or all groups of sensors  58 , are activated, the fan  28  is increased to full speed. The three-speed operation may be two-speed, four-speed, five-speed, or a continuous speed, if required or desired. 
         [0072]    In this way the operation of the fan assembly  24  can be controlled in an automatic manner based on the number, nature and location of sensors activates to thus reduce electricity consumption, but still allowing manual override if required or desired. This is applicable in commercial kitchens, car parks, cooling tower fans, production facilities, factories, warehouses, retail centres, offices, or the like. 
         [0073]    Whilst there has been described in the foregoing description preferred embodiments of the present invention, it will be understood by those skilled in the technology concerned that many variations or modifications in details of design or construction may be made without departing from the present invention.