Abstract:
A fluid fuel consuming apparatus (such as a gas fire) is disposed in a room of a building and a supply of fluid fuel is connected to the apparatus via a valve unit ( 10 ) disposed in the same room. The valve unit comprises a valve member ( 18 ) movable between a closed position blocking a fuel pathway between its inlet and outlet ports ( 48 I, 48 O) and an open position opening the fuel pathway A gas detector ( 42 C, 42 H) is mounted in the valve unit for detecting the presence of a particular gas (such as carbon monoxide) and/or group of gases (such as hydrocarbons) in the atmosphere around the valve unit. The valve member, if in the open position, is automatically moved from its open to its closed position in response to the detection of the presence of such gas.

Description:
BACKGROUND OF HE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to a valve system for a fluid fuel. 
         [0003]    The invention was originally conceived as a gas valve system for a gas fire supplied from the gas main. However, it is also applicable for use with other apparatuses, such as boilers and stoves, which may be supplied with gas from other sources such a bottled gas, and to apparatuses employing other fuels, such as boilers using heating oil. 
         [0004]    2. Description of the Related Art 
         [0005]    Gas fires can be dangerous. The gas supply pipe may leak or the gas fire may be without a functioning device for cutting off the gas supply if the fire is not alight. As a result, the room containing the gas fire may fill with hydrocarbon gas (e.g. methane, butane or propane) with the consequent risk of explosion and possibly of suffocation if the gas replaces too much of the oxygen in the room. Also, if the fire is not burning efficiently and is producing excessive toxic carbon monoxide, particularly if the outlet flue from the fire is not working properly, occupants of the room may be poisoned. 
         [0006]    The supply pipe to a gas fire is typically fitted with manually operable valve adjacent the gas fire. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    It is an aim of the present invention, or at least of specific embodiments of it, to provide a small self-contained device which can reduce the risk of explosion, suffocation or poisoning caused by gas fires and other fluid fuelled apparatuses. 
         [0008]    In accordance with a first aspect of the present there is provided a valve system, for a fluid fuel, comprising a valve and a gas detecting means. The valve has: a valve body with inlet and outlet ports for connection to a supply of fluid fuel and to a fuel consuming apparatus, respectively, and a fuel pathway extending between the inlet and outlet ports; a valve member movable between a closed position blocking the fuel pathway and an open position opening the fuel pathway; and moving means operable for moving the valve member, if in the open position, from the open position to the closed position. The gas detecting means is arranged for detecting the presence of a particular gas (such as carbon monoxide) and/or group of gases (such as hydrocarbons) in the atmosphere around the gas detecting means; in response to the detection of the presence of such gas. The gas detecting means is provided as a single unit with the valve and is mounted on the valve body. The moving means is arranged to operate in response to the gas detecting means so that the valve member, if in the open position, automatically moves from the open position to the closed position in response to detection of the presence of the gas or group of gases around the valve. 
         [0009]    In accordance with a second aspect of the present invention, there is provided an installation, comprising: a fluid fuel consuming apparatus (such as a gas fire) disposed in a room of a building; and a supply of fluid fuel connected to the apparatus via a valve system according to the first aspect of the invention; wherein the valve unit is disposed in the same room as the apparatus. 
         [0010]    Preferably, the valve unit cuts off the fuel supply before the concentration of gas becomes so great as to be dangerous and therefore prevents the situation getting worse. Of course, if there is a fuel leak upstream of the valve unit, closing the valve will not stop the leak. However, the fact that the fuel supply has been turned off and/or the provision of an audible and/or visual alarm may serve to alert the occupant to the hazard and cause them to investigate the source of the problem. 
         [0011]    The gas detecting means is preferably operable to measure the concentration of the particular gas or group of gases in the atmosphere around the valve system and to detect the presence of such gas by comparing the measured concentration with a threshold valve. 
         [0012]    In addition to having a gas detection facility, the valve system may further include means for detecting whether the ambient temperature exceeds a threshold, with the moving means being arranged to operate in response to the temperature detecting means so that the valve member, if in the open position, automatically moves from the open position to the closed position in response to the ambient temperature exceeding the temperature threshold. The system can therefore also cut of the fuel supply in the event of fire. 
         [0013]    The valve system is preferably arranged to be powered by a battery, so that it does not need a connection to an external electricity supply. In this case, the valve system preferably has a space for housing the battery. Also, the valve system preferably further includes means for detecting whether the battery voltage or charge is below a threshold, with the moving means being arranged to operate in response to the battery detecting means so that the valve member, if in the open position, automatically moves from the open position to the closed position in response to the battery voltage or charge detection being below the battery threshold. Therefore, when the battery is near exhaustion, it cuts off the fuel supply until the battery is replaced. 
         [0014]    In a preferred embodiment of the invention, said moving means comprises: a spring for urging the valve member from the open position to the closed position; a latch for holding the valve member in the open position; and means for releasing the latch. In this case, the means for releasing the latch may comprise a solenoid, and the solenoid may also be operable to engage the latch. 
         [0015]    In a preferred embodiment of the invention, the valve system further includes: a manually operable element for moving the valve member from its closed position to its open position. A position detecting means may also be provided for detecting the position of the valve member. 
         [0016]    In a preferred embodiment of the invention, the valve system includes a microcontroller responsive to said gas detecting means and operable to control said moving means. 
         [0017]    The microcontroller may be operable to perform an initialization routine, comprising the steps of: (i) causing the solenoid to release the latch at least if the valve member is in the open position; (ii) employing the position detecting means to detect movement of the valve member from its closed position to its open position caused by operation of the manually operable element; (iii) employing the gas detecting means to detect the presence of the particular gas or group of gases; and (iv) causing the solenoid to engage the latch only in the absence of the particular gas or group of gases. The valve system will therefore not latch open in dangerous circumstances. 
         [0018]    In the case where the gas detecting means consumes power during operation, the microcontroller is preferably operable to perform a looping routine comprising the repeating steps of: (i) causing power to be supplied to the gas detecting means; (ii) employing the gas detecting means to detect the presence of the particular gas or group of gases; (iii) ceasing the supply of power to the gas detecting means; and (iv) waiting for a time interval. The system therefore monitors the gas intermittently, rather than continuously, so reducing the power consumption of the unit and increasing battery life. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0019]      FIG. 1  is a schematic front view of a gas valve unit; 
           [0020]      FIG. 2  is a schematic front view of the gas valve unit with its cover removed; 
           [0021]      FIG. 3  is a schematic cross-sectioned rear view of the gas valve unit in its “off” state; 
           [0022]      FIG. 4  is a schematic cross-sectioned rear view of the gas valve unit in its “on” state; 
           [0023]      FIG. 5  is a circuit block diagram of the gas valve unit; and 
           [0024]      FIG. 6  is a flow diagram illustrating the operation of the gas valve unit. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    Referring to  FIGS. 1 to 4 , a gas valve unit  10  comprises a valve block  12  and a cove  14  which can be fitted over the valve block  12  to form a cavity  16  above the valve block  12 . A valve member  18  is mounted in the valve block  12  and has a stem  20  which projects upwardly from the valve block  12 , through the cavity  16  and through a hole in the upper wall  22  of the cover  14  to a control button  24  outside the cover  14 . Inside the cavity  16 , there are mounted: a printed circuit board (PCB)  26 ; and a solenoid  28 , a microswitch  30 , and a battery  32  connected to the PCB  26 . On the PCB  26 , there are mounted a PIC microcontroller  34 , five indicator light-emitting diodes (LEDs)  36 B,  36 C,  36 H,  36 T,  36 V, a beeper or buzzer  38 , a “test” push-button switch  40 , a carbon dioxide (CO) gas sensor  42 C, a hydrocarbon (HC) gas sensor  42 H and a temperature sensor  44 . The front wall of the cover  14  is perforated by holes  46  so that the ambient air can readily reach the gas sensors  42  and temperature sensor  44 , so that sound produced by the beeper  38  can escape from the cavity  16 , and so that the test switch  40  can be manually operated. The front wall of the cover  14  is also perforated by holes or is transparent in the region of the LEDs  36  so that they can be seen from the outside. The cover  14  is labelled to indicate the functions of the LEDs  36  and test switch  40 . 
         [0026]    Referring in particular to  FIGS. 3 and 4 , the valve block  12  has an inlet port  48 I leading into the valve block  12  from the right and for connection to a gas pipe  50 I leading from the gas main. The valve block  12  also has an outlet port  48 O leading out from the valve block  12  to the left above the inlet port  48 I and for connection to a gas pipe  50 O leading to a gas appliance such a gas fire. A valve seat  52  is formed around a passageway  54  leading from the inlet port  48 I to the outlet port  48 O. The valve member  18  is slidable vertically in the valve block  12 , guided at the lower end of the stem  20  by a plug  56  screwed into the valve block  12 , and guided by a hole with a seal  58  leading from the valve block  12  to the cavity  16 . The valve member  18  has a head  60  provided with a seal  62  which can engage with the valve seat  52  when the valve member  18  is in its uppermost “closed” position to block the passageway  54  and thus close the valve unit  10 , as shown in  FIG. 3 . When the valve member  18  is in its lowermost “open” position, the passageway  54  is open so that gas can flow from the inlet port  50 I to the outlet port  50 O, as shown in  FIG. 4 . The valve member  18  is urged towards the closed position by a compression spring  64  acting between the plug  56  and the underside of the valve head  60 . 
         [0027]    The solenoid  28  has an armature  66  and is of the double-acting type, so that when a voltage of one polarity is applied to the coil of the solenoid  28 , the armature is urged to the right, and when a voltage of the opposite polarity is applied to the coil of the solenoid  28 , the armature is urged to the left. The armature  66  is damped so that it tends to stay in the position to which it has been moved by the solenoid coil. The valve stem  20  has a square-sided annular groove  68  which becomes aligned with the armature  66  when the valve unit  10  is in its open position. Therefore, if, from the closed position of  FIG. 3 , the valve member  18  is pressed downwardly by finger pressure on the control button  24 , and if the solenoid  28  is then pulsed to move its armature  66  to the right into the groove  68 , and if the finger pressure is then removed from the control button  24 , the armature  66  will remain in the groove  68  and lock the valve unit  10  in its open position, as shown in  FIG. 4 . From that position, if the solenoid  28  is then pulsed to move its armature  66  to the left out of the groove  68 , the action of the spring  64  will lift the valve member  18  to change the valve unit  10  back to its closed position, as shown in  FIG. 3 . 
         [0028]    The microswitch  30  has a spring-loaded operating element  70  which is urged against the valve stern  20 . The valve stem has a further annular groove  72  which becomes aligned with the operating element  70  when the valve unit  10  is open ( FIG. 4 ), in which case, the microswitch  30  is in its “off” state. When the valve unit  10  changes to its closed position ( FIG. 3 ), the operating element  70  of the microswitch  30  rides out of the groove  72  and becomes depressed, so that the microswitch  30  changes to its “on” state. 
         [0029]    The gas sensors  42  are electrically powered. The CO gas sensor  42 C produces an analogue electrical signal which is approximately linearly related to the concentration of CO in the ambient air, and which is substantially independent of other gases. The IC gas sensor  42 H produces an analogue electrical signal which is approximately linearly related to the concentration of combustible gases in the ambient air, namely hydrogen, methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonan, ethane, acetylene and isobutylene, but which is substantially independent of non-combustible gases. Such sensors are available off the shelf, examples being the “CO-D4” carbon monoxide sensor and the “CH-D3” combustible gas pellistor produced by Alphasense Limited, CM77 7AA, United Kingdom. The temperature sensor  44  may be provided by a passive thermistor or by an active temperature sensing semiconductor device requiring a power supply. In either case, the temperature sensor  44  produces an analogue electrical signal dependent on its temperature. 
         [0030]    Referring now to  FIG. 5 , the microcontroller  34  receives electrical power from the battery  32  and can selectively supply power to the gas sensors  42  (and if need be to the temperature sensor  44 ) when readings are to be taken from the sensors  42 , 44 . The microcontroller  34  has analogue-to-digital converters  74 B, 74 C, 74 H, 74 T which receive the battery voltage and the output signals from the sensors  42 C, 42 H, 44  and produce digital signals related to the battery voltage, the CO concentration, the HC concentration and the temperature. The microcontroller  34  can sense the states of the valve-operated microswitch  30  and the manually-operable test switch  40 . The microcontroller  34  can supply a driving voltage of either polarity to the coil of the solenoid  28 . The microcontroller  34  can also send output signals to the LEDs  36  and to the beeper  38 . 
         [0031]    The microcontroller  34  is programmed to operate in the manner that will now be described with reference to  FIG. 6 . 
         [0032]    Initialisation Routine. 
         [0033]    When power is initially supplied to the microcontroller  34  upon connection of the battery  32 , the microcontroller  34  performs an initialisation routine. In step  76  the microcontroller  34  sends a pulse to the solenoid  28  so that if its armature  66  is engaged with the groove  68  in the valve member  18 , it becomes disengaged. After step  76 , the valve unit  10  should therefore be in its closed position. In step  78 , the state of the valve switch  30  is checked. If it indicates that the valve is open (indicating for example that the valve member  18  is stuck or there is a fault with the circuitry), the flow proceeds to step  80  which will be described later. However, if in step  78  the valve switch  30  indicates that the valve is not open, the flow proceeds to step  82  and loops there, checking the valve switch  30  and waiting for it to indicate that the valve has been opened as a result of the control button  24  being depressed. 
         [0034]    Once the valve switch  30  indicates that the valve is open, in step  84  the microcontroller  34  activates the sensors  42 , 44  by supplying power to them. Then in step  86  the microcontroller  34  compares the value of the signal from the A-to-D converter  74 C for the CO sensor  42 C with a programmed threshold. The programmed threshold is chosen to represent a level of CO in the air indicative of the gas not combusting properly in the gas appliance. If the CO value is higher than the threshold, in step  88  the microcontroller  34  toggles on the CO warning LED  36 C and then proceeds to step  90  to be described later. If in step  86  the CO value is not higher than the threshold, then in step  92  the microcontroller  34  compares the value of the signal from the A-to-D converter  74 H for the HC sensor  42 H with a programmed threshold. The programmed threshold is chosen to represent a level of HC in the air indicative of a gas leak. If the HC signal is higher than the threshold, in step  94  the microcontroller  34  toggles on the HC warning LED  36 H and then proceeds to step  90 . If in step  92  the HC value is not higher than the threshold, then in step  96  the microcontroller  34  compares the value of the signal from the A-to-D converter  74 T for the temperature sensor  44 C with a programmed threshold. The programmed threshold is chosen to represent a temperature indicative of there being a fire nearby. If the temperature value is higher than the threshold, in step  98  the microcontroller  34  toggles on the temperature warning LED  36 T and then proceeds to step  90 . If in step  96  the temperature value is not higher than the threshold, then in step  100  the microcontroller  34  deactivates the sensors  42 , 44  by cutting the power to them. Then, in step  102  the microcontroller  34  compares the value of the signal from the A-to-D converter  74 B for the battery voltage with a programmed threshold. The programmed threshold is chosen to be indicative that the battery  32  is nearing the end of its life but still has sufficient charge to enable operation for a short time thereafter. If the battery voltage value is less than the threshold, in step  104  the microcontroller  34  toggles on the low battery warning LED  36 B and then proceeds to step  106  which will be described later. If in step  102  the battery voltage value is higher than the threshold, then in step  108  the microcontroller  34  checks the state of the valve switch  30 . If the valve is not still open, indicating that the user has not kept the control button  24  depressed, the flow loops hack to step  82 . However, if the valve is still open, in step  110  the microcontroller  34  sends a pulse to the solenoid  28  to engage its armature  66  in the groove  68  in the valve member  18 , and in step  112  the microcontroller  34  causes the beeper  38  to generate a single beep, indicating to the user that they may now release the control button  24 . Upon release of the control button  24 , the solenoid armature  66  should maintain the valve in its open position. In step  114 , the microcontroller wait for a short period of time such as 5 seconds, and then in step  116 , the microcontroller  34  checks the state of the valve switch  30 . If the valve is not still open, indicating that there is a fault, the flow proceeds to step  80  which will be described later. However, if the valve is still open, the initialisation routine is complete, and the flow proceeds to step  120 . 
         [0035]    Regular Looping Routine. 
         [0036]    After the initialisation routine described above, the microcontroller  34  performs a looping routine. In step  120  the microcontroller  34  waits for a programmed time interval such as 5 minutes while monitoring the state of the test switch  40 . If the test switch  40  is operated during that time interval, the flow proceeds to step  122  which will be described later. However, if the end of the programmed time interval is reached without the test switch  40  being operated, the flow proceeds to step  124 . Step  124  and its subsequent steps  126 ,  128 ,  130 ,  132 ,  134  are identical to steps  84 ,  86 ,  92 ,  96 ,  100  and  102 , respectively, described above in connection with the initialisation routine. If problems are detected, the flow branches to step  88 ,  94 ,  98  or  104  as appropriate. However, if there are no problems, after the battery voltage check in step  134 , the flow loops back to step  120 . 
         [0037]    Test Routine. 
         [0038]    If, in step  120 , the test switch  40  is operated during the programmed wait period, then in step  122  the microcontroller  34  sends a pulse to the solenoid  28  so that its armature  66  should disengage from the groove  68  in the valve member  18 , as a result of which the valve unit  10  should change to its closed position. Then, in step  123 , the microcontroller  34  checks the state of the valve switch  30 . If the valve is open, indicating that there is a fault, the flow proceeds to step  80 , otherwise the flow jumps to step  82  waiting for the user to depress the control button  24 . 
         [0039]    Warning Routines. 
         [0040]    In the event that the flow reaches step  90  from step  88 ,  94  or  98  while the sensors  42 C, 42 H, 44  are activated, then in step  90  the microcontroller deactivates the sensors  42 C, 42 H, 44  and then proceeds to step  106 . 
         [0041]    In the event that the flow reaches step  106 , either from step  90  or  104 , then in step  106  the microcontroller  34  sends a pulse to the solenoid  28  so that its armature  66  should disengage from the groove  68  in the valve member  18 , as a result of which the valve unit  10  should change to its closed position. Then in step  124 , the microcontroller  34  checks the state of the valve switch  30 . If the valve is open, indicating that there is a fault, the flow proceeds to step  80 , otherwise the flow jumps to step  126 . 
         [0042]    In the event that the flow reaches step  80 , from step  78 ,  116 ,  123  or  124  as a result of the valve state not being as expected, then in step  80  the microcontroller  34  toggles on the valve fault warning LED  36 V. The flow then proceeds to step  126 . 
         [0043]    In the event that the flow reaches step  126 , from step  80  or  124 , in step  126  the microcontroller  34  toggles on the beeper  38 , and the routine then stalls at step  128 , with the beeper  126  sounding and those of the LEDs  36  that have been toggled on remaining on until the battery  32  either goes flat or is disconnected. 
         [0044]    It will therefore be appreciated that the microcontroller  34  regularly powers up the sensors  42 C, 42 H, 44 , checks their outputs and also the battery voltage, and if necessary closes the valve, raises an alarm with the beeper  38  and indicates with the LEDs  36  the cause of the alarm. During the normal looping operation after initialisation, the solenoid does not consume any battery power, all of the LEDs are off, and the sensors  42 C, 42 H and  44  are powered up only intermittently in order to conserve battery life. 
         [0045]    It will be appreciated that many modifications and developments may be made to the embodiment of the invention described above. For example, the valve unit  10  may be employed in a supply pipe to other gas appliances such as boilers and cooking stoves. The valve unit  10  may also be used in a supply pipe for heating oil to an oil-fired boiler. In this case in particular, the hydrocarbon gas sensor  42 H may be omitted. Although it is preferred that the valve unit  10  is battery operated, it may be powered by mains electricity, in which case the gas sensors  42 C, 42 H may be powered continuously. Although the solenoid armature  66  has been shown in the drawings as acting directly on the valve member  18 , it may instead operate through a lever. 
         [0046]    It should be noted that the embodiment of the invention has been described above purely by way of example and that many other modifications and developments may be made thereto within the scope of the present invention.