Electromagnetic valve security device for fuel supplies

An electromagnetic valve circuit used in a fluid line security device is disclosed. The circuit is adapted to open and close a fuel supply pipe. The circuit includes an attracting circuit and a holding circuit connected to one side of a power source. The attracting circuit including an attracting switch is in parallel with the attraction holding circuit. The attracting switch is closed only when the attraction phase of value opening is to be accomplished. In one modification the series circuit of the attracting switch and the electromagnetic valve circuit is coupled in parallel to a circuit formed by a hazard detecting switch, and a relay switch operating coil. In another modification a time limit current control is connected in series with the valve coil to control the supply of current to the coil for a predetermined time limit.

BACKGROUND OF THE INVENTION 
This invention relates to an electromagnetic valve in a security device for 
fuel, such as natural gas, propane or the like, in which an 
electromagnetic valve circuit is used to open and close a pipe through 
which fuel flows. The circuit is made up of an attracting circuit and an 
attraction holding circuit. 
The performance of an electromagnetic valve is as shown in FIG. 1; that is, 
when the electromagnetic valve carries out the attraction phase, it 
requires a large attracting current I.sub.O according to the valve stroke; 
however, after being attracted, the electromagnetic valve can be 
maintained attracted with a small attraction holding current I.sub.M. In a 
conventional electromagnetic valve operating method, current for 
attraction is allowed to flow in the electromagnetic valve at all times. 
Therefore, the conventional electromagnetic valve operating technique is 
disadvantageous in that current is consumed wastefully where the 
electromagnetic valve is placed in the attraction state for a long period 
of time. 
Accordingly, in view of the above-described difficulties accompanying the 
conventional method, an object of this invention is to provide an 
electromagnetic valve in a security device for fuel, in which no wasteful 
current consumption is caused when the electromagnetic valve is maintained 
open by applying current thereto for a long period of time. 
Another object of this invention is to provide an electromagnetic valve 
circuit in a security device for fuel that eliminates the generation of 
heat when the reset switch is closed erroneously such that the 
electromagnetic valve coil draws a large attracting current. 
Still another object of this invention is to provide for a valve circuit 
that minimizes power consumption. 
An important aspect of this invention resides in a circuit for an 
electrogmagnetic valve that is made up of an attracting circuit and an 
attraction holding circuit. The attracting circuit is connected in 
parallel to the attraction holding circuit through an attracting switch 
which is closed only when the attraction is effectuated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
This invention will be described with reference to its preferred 
embodiments. First, the invention will be described with reference to the 
security device shown in FIG. 2 for fluid fuel such as gas, which device 
employs an electromagnetic valve which is electrically opened for a long 
period of time. In such a security device a timer motor TM is connected to 
an electric source E, operated at all times. Connected to one terminal of 
the electric source E are terminal A of a reset switch SW1 and terminal A 
of a circuit "off" switch SW2. Terminal B of the circuit "off" switch SW2 
is connected to terminal C of a relay switch SW3, the other terminal D of 
which is connected to terminal F of the reset switch SW1. Terminals D and 
F of switches SW1 and SW3 are connected to one terminal of a primary 
winding P of a transformer T and to one terminal of a pilot lamp 6. The 
other terminals of the primary winding P and the pilot lamp 6 are 
connected through a timer switch SW7 to the other terminal of the electric 
source E. 
One terminal of a secondary winding S of the transformer T is connected to 
terminal J of a gas leakage detecting switch SW5, a hazard detecting 
switch, and to terminal G of an attracting switch SW4. Terminal K of the 
gas leakage detecting switch SW5 is connected to terminal M of an 
earthquake detecting switch SW6, another hazard detecting switch. Terminal 
N of the earthquake detecting switch SW6 is connected to one terminal of a 
relay switch operating coil RL and to one terminal of an attraction 
holding resistor 2 in an attraction holding circuit. Terminal H of the 
attracting switch SW4 and the other terminal of the attraction holding 
resistor 2 are connected to the attracting circuit of a main valve 
constituted by an electromagnetic valve. 
The attracting circuit comprises a valve coil L1. The common or ground 
terminal of the valve coil L1 and the other terminal of the relay switch 
operating coil RL are connected to the other terminal of the secondary 
winding S of the transformer T. 
In this circuit, the rests switch SW1 and the attracting switch SW4 are 
normally-open-switches, and are operated in association with each other. 
The circuit "off" switch SW2 is a normally-closed-switch. The gas leakage 
detecting switch SW5 and the earthquake detecting switch SW6 are 
normally-closed-switches forming an OR circuit. The relay switch SW3 is a 
normally-open switch. The timer switch SW7 is opened and closed in a 
period of 24 hours depending on the setting which is adjustable. 
The ends of the main valve are connected respectively to a gas flow pipe 3 
and a piping 5 of gas utensils 4. The main valve 1 is a normally-closed 
valve. The pilot lamp 6 is connected between terminal D of the relay 
switch SW3 and terminal P of the timer switch SW7. The attracting switch 
SW4 may be designed so that it is operated by the valve coil L1 in such a 
manner that it is opened and closed in correspondence with the action of 
the main valve 1. 
The operation of the fluid fuel security device of FIG. 2 thus constructed 
will now be described. The period of time during which the timer switch 
SW7 is opened is set to the period of time during which no gas is needed 
(hereinafter referred to as "a gas non-use time period" when applicable). 
It is assumed, for example that the gas non-use time period is from 12 
o'clock p.m. to 6 o'clock a.m. next morning. If the reset switch SW1 is 
closed by depression during the period of time from 6 a.m. to 12 p.m., 
then the primary winding P of the transformer T is energized and a voltage 
is developed across the secondary winding S of the transformer T. As a 
result, the valve coil L1 of the main valve 1 is energized through the 
attracting switch SW4 which is closed in association with the depression 
of the reset switch SW1. An attracting current I.sub.O flows in the valve 
coil L1, so that the valve 1 is opened. On the other hand, the voltage of 
the secondary winding S is applied through the gas leakage detecting 
switch SW5 and the earthquake detecting switch SW6 to the relay switch 
operating coil RL, the attraction holding resistor 2, and the valve coil 
L1 of the main valve 1. Thus, the aforementioned attracting current 
I.sub.O and an attraction holding current I.sub.M passing through the 
attraction holding resistor 2 bath flow in the valve coil L1. The relay 
switch SW3 of the relay switch operating coil RL is closed by the 
application of current described above, and therefore the primary winding 
of the transformer T is maintained energized even if the depression of the 
reset switch SW1 is released. Upon release of the depression of the reset 
switch SW1, the attracting switch SW4 is opened. As a result, the 
application of the attracting current I.sub.O is suspended, and the main 
valve 1 is maintained opened by the attraction holding current I.sub.M. 
When a hazard occurs, for example a crack in the gas piping or an 
earthquake, the hazard detecting switch SW5 or SW6 is opened to suspend 
the application of current to the valve coil L1 of the main valve 1. As a 
result, the main valve 1 is closed, so that the supply of gas to the 
piping 5 is stopped and the pilot lamp 6 is turned off. 
In the case of electrical service interruption also, the relay switch SW3 
is closed to close the main valve. The main valve 1, once closed, cannot 
be opened unless the reset switch SW1 and the attracting switch SW4 are 
closed by depression. 
If a user wants to close the main valve 1, for instance before he leaves 
his house, the circuit "off" switch SW2 can be opened by depression. In 
this case, the relay switch operating coil RL and the valve coil L1 of the 
main valve 1 are deenergized, and therefore the main valve 1 is closed. 
When the main valve 1 is to be opened during a subsequent gas use time 
period, the reset switch SW1 and the attracting switch SW4 are depressed. 
During the period of time during which the timer is not used (hereinafter 
referred to as "a timer non-use time period", when applicable), the timer 
switch SW7 is opened. As a result, the relay switch operating coil RL and 
the valve coil L1 of the main valve 1 are deenergized, the pilot lamp 6 is 
turned off, and the main valve is closed. When the reset switch SW1 is 
depressed for the period of time during which the timer is used, as for 
example, the next morning, the attracting switch SW4 and the relay switch 
SW3 are closed. As a result, the main valve 1 is opened. If a requirement 
exists for gas usage during the above-described gas non-use time period, 
it is necessary to change the "on" period of time in the timer and to 
depress the reset switch SW1. The timer is designed so that the gas 
non-use time period can be changed within a range of from, for instance, 2 
hours to 8 hours as desired by the user. In the circuit of the security 
device, the starting side comprising switches SW1, SW2, SW3 and SW7 is 
separated by the transformer T from the operating side comprising the main 
valve 1, the switches SW4, SW5 and SW6, and the relay switch operating 
coil RL. Therefore, even if the voltage of the electric source E is high, 
the circuit can operated at a low voltage. Accordingly, difficulties such 
as electric shock caused by the leakage of high voltage into gas utensils 
can be prevented; that is, security is improved. In addition, as the relay 
switch SW3 is provided on the side of the primary winding of the 
transformer T and the relay switch operating coil RL is provided on the 
side of the secondary winding S of the transformer T, the current flowing 
in the primary winding side of the transformer T is interrupted when the 
main valve 1 is closed. This is advantageous in view of power consumption 
and security. 
As shown in FIG. 3 a main valve 1 is provided with an attracting valve coil 
L1 and an attraction holding valve coil L2. When it is required to close 
the main valve 1, an attracting current I.sub.O is allowed to flow in the 
attracting valve coil L1 to attract the main valve. The main valve thus 
attracted is maintained in position by feeding an attraction holding 
current I.sub.M to a series circuit of the attracting valve coil L1 and 
the attraction holding coil L2. The same effect can be obtained by 
allowing a large current I.sub.O and a small current I.sub.M to flow 
respectively in an attracting valve coil L1 and an attraction holding 
valve coil L2 provided separately for the main valve 1. 
FIG. 4 shows a modification of the FIG. 2 circuit obtained by directly 
connecting the starting side and the operating side by removing the 
transformer T. More specifically, a circuit "off" switch SW2, a relay 
switch SW3 and a gas leakage detecting switch SW5 and an earthquake 
detecting switch SW6 are connected in series to one terminal of an 
electric source E. A reset switch Sw1 is connected in parallel to this 
series circuit, with terminal D of the relay switch SW3 being connected to 
an attracting switch SW4. A relay switch operating coil RL and a pilot 
lamp 6 are connected between terminal F of the reset switch SW1 and 
terminal P of a timer switch SW7. In this circuit, the circuit is applied 
to the relay switch operating coil RL directly by closing the reset switch 
SW1. 
The operation of the circuit shown in FIG. 4 will now be described. Similar 
to the circuit shown in FIG. 2, during the gas use time period, the reset 
switch SW1 and the attracting switch SW4 are closed to apply an attracting 
current I.sub.O to the valve coil L1 of the main valve 1 and to apply an 
attraction holding current I.sub.M through an attraction holding resistor 
2 to the valve coil L1. At the same time, the relay switch operating coil 
RL is energized to close the relay switch SW3. Upon closure of the relay 
switch SW3, the supply of current to the relay switch operating coil RL, 
the attraction holding resistor 2 and the valve coil L1 is maintained even 
if the depression of the reset switch SW1 is released. Therefore, the main 
valve 1 thus attracted is maintained open by the attraction holding 
current I.sub.M. 
The electric source E may be the commercial power supply or a battery 
electric source. A synchronous motor or a step motor is used as the timer 
motor depending on the electric source employed in the circuit. 
FIG. 5 shows another modification of the circuit shown in FIG. 2. The 
attracting switch SW4, the attraction holding resistor 2, and the gas 
leakage detecting switch SW5 are connected to one terminal of the 
secondary winding S of the transformer T. The other terminal of the 
attracting switch SW4 and the other terminal of the attraction holding 
resistor 2 are connected to one terminal of the valve coil L1 in the 
attracting circuit. The other common terminal of the valve coil L1 is 
connected to the other terminal of the secondary winding S of the 
transformer T. The gas leakage detecting switch SW5 is connected to the 
series circuit of the earthquake detecting switch SW6 and the relay switch 
operating coil which is connected to the secondary winding S of the 
transformer T. 
In the above description, the electromagnetic valve is employed as the main 
valve for gas which is fluid fuel. However, this invention may be applied 
to the attracting circuit and attraction holding circuit of 
electromagnetic valves which are used for other fluid fuels. 
With the electromagnetic valve operating circuit constructed as was 
described above, the electromagnetic valve can be attracted and held with 
1/10 of the attracting current. Therefore, ineffective, or useless, 
current flows in the circuit, and the electrical capacity of the circuit 
can be so small because the attracting current is allowed to flow therein 
for only a short time. 
Also, since the attracting switch and the attracting electromagnetic valve 
circuit are connected in parallel to the hazard detecting switch group to 
bypass the flow of current, the electrical capacity of the hazard 
detecting switch group can be small. Because the amount of current flowing 
through the switches is decreased, problems such as poor conduction due to 
the wear of the contacts thereof is eliminated, which leads to the stable 
operation of the device. 
As demonstrated in the above described embodiments, the valve coil of the 
main valve 1 requires a large attracting current I.sub.O for the valve 
stroke during the attraction phase. Once that phase is complete the 
attraction state can be maintained with a small attraction holding current 
I.sub.M as shown in FIG. 1. 
In all of the circuits shown in FIGS. 2, 4 and 5, the attracting switch SW4 
is operated in conjunction with the reset switch SW1. Hence during the 
conduction phase, current switching is manually accomplished by ganged 
operation of the switches. Therefore, if the reset switch is erroneously 
depressed for a long period of time a large attracting current will flow 
in the transformer T or in the electromagnetic valve coil L1. However, the 
capacity of the transformer is small because it is designed for 
maintaining the low level attraction holding current and not for a long 
time period of the large attracting current. Hence, problems of heat 
generation may occur in the transformer T of the electromagnetic valve 
coil L1 of the prior embodiments if reset switch is inadvertantly held 
depressed. 
In view of this potential problem, the embodiments of FIGS. 6-9 provide an 
electromagnetic valve circuit in a security device for fuel wherein even 
if the reset switch is erroneously closed for a long period of time, no 
abnormally high heat will be generated in either the transformer or the 
electromagnetic valve coil as a result of the large attracting current. 
Referring now to FIG. 6, a timer motor TM is connected to an electric 
source E and is operated at all times. One terminal of the electric source 
E is connected to terminal A of a reset switch SW1 and to terminal A of a 
circuit "off" switch SW2. Terminal B of the "off" switch is connected to 
one terminal of a relay switch SW3. Terminal D of the relay switch SW3 is 
connected to terminal F of the reset switch SW1. 
The remaining terminals D and F of switches SW1 and SW3 are connected to 
one end of a primary winding P of a transformer T and to one terminal of a 
pilot lamp 6. The other end of the primary winding P and the other 
terminal of the pilot lamp 6 are connected through a timer switch SW7 to 
the other terminal of the electric source E. One end of a secondary 
winding S of the transformer T is connected to terminal J of a hazard 
detecting switch, namely, a gas leakage detecting switch SW5, one terminal 
of a timer t, one terminal of a timer switch SW8, and one terminal of an 
attraction holding fixed resistor 21. The other terminals of the timer 
switch SW8 and attraction holding fixed resistor 21 are connected to one 
terminal of an electromagnetic valve coil L1. The other terminal K of the 
gas leakage detecting switch SW5 is connected to terminal M of another 
hazard detecting switch, namely, an earthquake detecting switch SW6. 
Terminal N of switch SW6 is connected to one terminal of a relay switch 
operating coil RL. The other terminals of the relay switch operating coil 
RL, timer t and electromagnetic valve coil L1 are connected to the other 
end of the secondary winding S of the transformer T. 
The reset switch SW1 is a normally-open switch, and the circuit "off" 
switch SW2 is a normally-closed switch. The hazard detecting switches, 
that is, the gas leakage detecting switch SW5 and the earthquake detecting 
switch SW6, are normally-closed switches forming an OR circuit. The relay 
switch SW3 is a normally-open switch which is opened upon energization of 
the relay switch operating coil RL. The timer switch SW7 is operable over 
a 24-hour period, and its open and closed periods can be set as desired. 
The ends of the main valve 11 are connected respectively to a gas flow 
pipe 3 and a piping 5 of gas utensils 4. The main valve 11 is a 
normally-closed valve. 
The operation of the security device of FIG. 6 for fuel will now be 
described. The period of timer during which the timer switch SW7 is open 
is set by timer TM to a gas non-use time period for example the time 
period during which the user is asleep. For instance, the gas non-use time 
period may be set to six hours from 00:00 to 06:00 hours. When the reset 
switch SW1 is depressed, or closed, during the 18-hour interval from 06:00 
o'clock to 00:00 o'clock, the primary winding P of the transformer T is 
energized, and a voltage is developed across the secondary winding S of 
the transformer T. Therefore, the timer t is operable so that the timer 
switch SW8 is closed in association with the operation of the timer t. As 
a result, a large attracting current flows in the electromagnetic valve 
coil L1, and therefore the main valve 11 is closed. On the other hand, the 
voltage developed across the secondary winding S is applied through the 
hazard detecting switches to the relay switch operating coil RL and 
directly to the attraction holding fixed resistor 21. Accordingly, a large 
attracting current passing through the timer switch SW8 is applied to the 
electromagnetic valve coil L1 when the latter performs the attraction 
step. The relay switch SW3 of the relay switch operating coil RL is closed 
by the energization described above, and therefore in the primary side of 
the transformer T the supply of current to the transformer is maintained 
even if the reset switch SW1 is released to open position. When a period 
of time set by the timer t elapses, the timer switch SW8 is opened, and 
therefore a small attraction holding current passed through the attraction 
holding fixed resistor 21 is supplied to the electromagnetic valve coil L1 
to maintain the main valve open. 
When either the gas leakage detecting switch SW5 or the earthquake 
detecting switch SW6 is opened, the supply of current to the 
electromagnetic valve coil L1 of the main valve 11 is suspended. 
Therefore, the main valve is opened and the supply of gas to the piping 5 
of the gas utensils 4 is stopped. In this case, the pilot lamp 6 is also 
turned off. In the case of a service interruption also, the relay switch 
SW3 is opened, so that the main valve 11 is closed. 
The main valve 11 thus closed cannot be opened without depressing (or 
closing) the reset switch SW1. If the user wants to close the main valve 
11, for instance, before he leaves his house, the circuit "off" switch SW2 
should be opened by depressing it. In this case, the relay switch 
operating coil RL and the valve coil L1 of the main valve 11 are 
deenergized, and therefore the main valve 11 is closed. When the main 
valve 11 is again to be opened during the gas use period of time, the 
reset switch SW1 should be closed by depressing it. 
During the timer non-use time period, the timer switch SW7 is opened. As a 
result, the relay switch operation coil RL and the electromagnetic valve 
coil L1 of the main valve 11 are deenergized. The pilot lamp 6 is turned 
off, and the main valve 11 is closed. When the use of gas during the gas 
non-use time period is required, it is necessary to reset the gas non-use 
time period and then to depress (or close) the reset switch SW1. The timer 
is designed so that the gas non-use time period can be changed within a 
range of from 2 hours to 8 hours as selected by the user. 
Shown in FIG. 7 is one modification of the security device shown in FIG. 6. 
One end of a secondary winding S of a transformer T is connected to 
terminal J of the aforementioned hazard detecting switch, namely, the gas 
leakage detecting switch SW5 and to one terminal of a posistor 7. Terminal 
K of the gas leakage detecting switch SW5 is connected to terminal M of 
another hazard detecting switch, namely, the earthquake detecting switch 
SW6. Terminal N of switch SW6 is connected to one terminal of a relay 
switch operating coil RL. The other terminal of the posistor 7 is 
connected to an electromagnetic valve coil L1. The other terminals of the 
electromagnetic valve coil L1 and relay switch operating coil RL are 
connected to the other end of the secondary winding S of the transformer 
T. 
In operation, upon depressing (closure) of the reset switch SW1, a voltage 
developed across the secondary winding S of the transformer T is applied 
to the posistor 7. Immediately after the application of the voltage, the 
resistance of the posistor 7 is small, and therefore a large attracting 
current flows in the electromagnetic valve coil L1, and the main valve 11 
is closed. Thereafter, as the temperature of the posistor 7 reaches a 
predetermined value, its resistance increases. As a result, a small 
attraction holding current flows in the electromagnetic valve coil L1, so 
that the main valve 11 is maintained operated. 
FIG. 8 shows another modification of the security device shown in FIG. 6. 
In the security device shown in FIG. 8, one terminal of a secondary 
winding S of a transformer T is connected to terminal J of the 
above-described gas leakage detecting switch SW5, terminal of a posistor 
71 and terminal of an attraction holding fixed resistor 22. Terminal K of 
the gas leakage detecting switch SW5 is connected to terminal M of the 
earthquake detecting switch SW6. Terminal N of switch SW6 is connected to 
one terminal of a relay switch operating coil RL. The other terminals of 
the posistor 71 and attraction holding fixed resistor 22 are connected to 
one terminal of an electromagnetic valve coil L1. The other terminal of 
the electromagnetic valve coil L1 and relay switch operating coil RL are 
connected to the other end of the secondary winding S of the transformer 
T. 
In operation, upon depression (closure) of the reset switch SW1 (not 
shown), a voltage developed across the secondary winding S of the 
transformer T is applied to the posistor 71 and the attraction holding 
fixed resistor 22. Immediately after the application of the voltage, the 
resistance of the posistor 71 is small. Therefore, a large attracting 
current passed through the posistor 71 and a small attraction holding 
current passing through the resistor 22 are allowed to flow in the 
electromagnetic valve coil L1 to open the main valve. Thereafter, as the 
temperature of the posistor 71 reaches a predetermined value, the 
resistance of the posistor 71 is increased. As a result, small attraction 
holding currents passing through the posistor 71 and the resistor 22 are 
allowed to flow in the electromagnetic valve coil L1 and the main valve 11 
is maintained opened. 
A further modification of the security device shown in FIG. 6 is 
illustrated in FIG. 9. In this modification, one end of a secondary 
winding S of a transformer T is connected to terminal J of the gas leakage 
detecting switch SW5 described above, one terminal of a capacitor 72 and 
one terminal of an attraction holding fixed resistor 23. Terminal K of the 
gas leakage detecting switch SW5 is connected to terminal M of the 
earthquake detecting switch SW6. Terminal N of switch SW6 is connected to 
one terminal of a relay switch operating coil RL. The other terminals of 
the capacitor 72 and fixed resistor 23 are connected to one terminal of an 
electromagnetic valve coil L1, the other terminal of which is connected 
through a diode 8 to the other terminal of the relay switch operating coil 
RL and other end of the secondary winding S of the transformer T. 
In operation, when the reset switch SW1 (not shown) is closed (or 
depressed), a voltage developed across the secondary winding S of the 
transformer T is applied to the capacitor 72 and the attraction holding 
fixed resistor 23. During the initial period of time after the application 
of the voltage, the capacitor 72 is being charged, and therefore a large 
attracting current comprising the current charging the capacitor 72 and a 
current passing through the fixed resistor 23 is allowed to flow in the 
electromagnetic valve coil L1 to open the main valve 11. When the 
capacitor 72 is fully charged, only a small attracting current passing 
through the fixed resistor 23 is allowed to flow in the electromagnetic 
valve coil L1, so the main valve 11 is maintained opened. 
As is apparent from the above description, according to these embodiments 
of the invention, even if the reset switch is erroneously depressed 
(closed) for a long time, abnormally high heat over the upper limit of the 
temperature range of the elements is never generated in either the 
transformer or in the electromagnetic valve coil. After the large 
attracting current necessary for opening the main valve is applied to the 
electromagnetic valve coil, the large attracting current is automatically 
replaced by the small attraction holding current. 
For this reason, the capacity of the transformer or the electromagnetic 
valve coil may be smaller than customarily used which leads to 
miniaturization of the device itself and the economical use of the same. 
Furthermore, as was described above, after the large attracting current is 
applied to the electromagnetic valve coil for an extremely short period of 
time required for opening the main valve, the large attracting current is 
replaced by the small attraction holding current. Therefore, the power 
consumption is reduced, which results in the direct saving of energy. 
Thus, the main valve can be controlled economically. Although embodiments 
and modifications have been shown, it is apparent that other changes may 
be made without departing from the essential scope of this invention.