Pipe closing device

The device is especially intended for a pipe supplying a fluid which must be supplied, simultaneously or alternately, with another fluid. The device comprises a tank for a control fluid which surrounds the vertical supply pipe and in which a permanent magnet moves in accordance with the amount of control fluid contained in the tank. The magnet shifts a valve member inside the supply pipe so that the valve member closes the latter in one of the end positions of the magnet. The magnet is rigid with a float which freely extends around the supply pipe. The device can in particular ensure that fuel is supplied to an engine only if oil is supplied to the latter.

The present invention relates to a device for closing a fluid pipe as a 
function of the flow or of the presence of another fluid, which is more 
particularly intended for the supply of a fluid which must be mixed with 
another fluid and is supplied simultaneously with this fluid at the same 
point or at a different point or, on the contrary, supplied alternately 
with this fluid. 
A typical example of the flow of fluids of this type is formed by the 
supply of petrol and oil of two-stroke engines which have a separate 
lubrication and in particular engines of two-wheeled vehicles. In these 
engines, the lubrication is achieved by supplying oil in the carburettor 
or in the crank-case by means of a pump driven by the engine. The vehicles 
therefore usually comprise an oil tank and a petrol tank which are 
separate so that the engine can continue to operate without lubrication 
when the oil tank is empty, which is a serious drawback and may result in 
the destruction of the engine. 
There has been proposed, in order to overcome this drawback, the use of a 
mixer in which the supply of petrol is controlled by the pressure of the 
oil, but this requires maintaining the oil at sufficient pressure and 
results in the automatic closing of the petrol supply when the engine 
stops, until the oil once again is supplied under pressure. Moreover, such 
an arrangement is only applicable in the case where the two fluids are 
intended to be mixed. 
An object of the present invention is to provide a closing device which may 
be adapted to structures in which the fluids are not intended to be mixed 
and which ensures the closure of the fluid pipe to be controlled in 
accordance solely with the presence of the second fluid, irrespective of 
the pressure of the latter. 
According to the invention, there is provided a device for closing a fluid 
pipe in accordance with the flow of another fluid, comprising a tank which 
is inserted in the circuit of the second fluid and through which the pipe 
of the fluid to be controlled extends and in which a permanent magnet 
moves in accordance with the amount of control fluid contained in the 
tank, and a valve member mounted inside the pipe, but constantly subjected 
to the attraction of the permanent magnet, which closes said pipe when the 
magnet is in one of its extreme positions and opens it as soon as the 
magnet leaves this extreme position. 
The pipe is consequently closed automatically upon the supply of the 
control fluid or upon the stopping of this supply, depending on the 
desired operational mode, without contact between the fluids. 
As the flow, or even the presence of the fluid in the tank, is the sole 
parameter controlling the valve member, the latter leaves its seat as soon 
as the fluid once again moves the magnet. 
In the case of a supply of petrol and oil of a two-stroke engine, the 
permanent magnet causes the closure of the valve member of the petrol pipe 
when the tank is empty, that is to say when the control oil flowing 
through this tank has been used up. The engine is then stopped and cannot 
start up again, which provides an effective safety measure. On the other 
hand, so long as the oil is present, the engine can be stopped and started 
up again immediately as quickly as desired.

As shown in the FIGURE, the pipe 1 through which flows the fluid whose flow 
must be regulated is provided with a check ball valve member whose seat 2 
is formed by an inner shoulder of this pipe and whose ball 3 is a steel 
ball whose diameter is slightly less than the inside diameter of the pipe 
1. Mounted around this valve is a tank or vessel 4 which is coaxial with 
the pipe 1 and provided with a nozzle 6 for the entry of fluid and a fluid 
outlet nozzle 7 in the extension of each other and located respectively on 
the two opposed walls of the tank through which the pipe 1 extends. Inside 
the tank, a float unit, comprising a float 8 of annular shape and a 
permanent magnet 10 rigid with the float, freely slides around the pipe 1. 
The ball 3 is constantly subjected to the attraction of the permanent 
magnet 10 since it is of steel and is thus maintained in the centre of the 
pipe 1 and shifted by the movement of the magnet. 
Consequently, when the tank 4 is full, which occurs in particular when the 
control fluid flows between the nozzle 6 and the nozzle 7, the float 8 is 
urged toward the upper end of the tank 4 and raises the magnet 10, which 
maintains the ball 3 in the position spaced away from the seat 2 shown in 
the FIGURE. Grooves are usually formed in the float to permit the fluid to 
continue to flow when the float is in this extreme position. 
On the other hand, when the supply of control fluid to the nozzle 6 ceases, 
the tank 4 is emptied and the float 8 moves downwardly and shifts the 
magnet 10 downwardly. The ball 3 is brought against the valve seat 2 and 
closes the pipe 1. The flow of the fluid in this pipe is consequently 
immediately stopped. 
Such a device is particularly adapted to the closure of the petrol supply 
pipe of a two-stroke engine the lubrication of which is achieved by the 
supply of oil in the carburettor or in the crank-case. 
The pipe 1 is then the petrol supply pipe which is connected in its upper 
part to the petrol tank and in its lower part to the carburettor. Mounted 
in this pipe 1, is a cylindrical end member 11 which is extended at both 
ends by nozzles 12 and 13 which are respectively the petrol inlet and 
outlet. The inner passage of each of these nozzles 12, 13 has a diameter 
less than the diameter of the pipe 1 which is itself less than cylindrical 
end member 11 so that an inner shoulder is formed at the junction between 
the nozzle and the member 11, the lower shoulder forming the seat 2. 
The end member 11 is rigid with the body of the tank 4 which is coaxial 
therewith and whose nozzles 6 and 7 are respectively connected to the oil 
tank and to the lubrication pump. When the oil flows normally toward this 
pump, the tank 4 is filled so that the ball 3 is held away from its seat. 
On the other hand, as soon as the oil has been used up, the ball 3 is 
returned into contact with the seat 2 and the supply of petrol is stopped, 
which constitutes a safety measure for the engine. 
The seat 2 may possibly comprise, as shown in the FIGURE, two studs 14 and 
15 from which electric conductors 16 extend, these conductors being 
connected to a source of current and to a signalling means. The studs 14 
and 15 are spaced apart a distance less than the diameter of the ball 3 so 
that the latter closes the signal actuating electric circuit when it is in 
the position for closing the valve. The operator, or possibly the driver 
of the vehicle, is in this way warned of the absence of oil. 
It will be understood that the device of the invention may be employed in 
other applications. For example, it may close the control valve of the 
pipe 1 when the fluid is present in the control pipe, the operation of the 
float or the position of the seat 2 being reversed. In this way, it may be 
employed for permitting the passage of the fluid in the pipe 1 when the 
fluid flows between the nozzles 6 and 7 or, on the contrary, as soon as 
the control fluid has ceased to flow. 
In any case, there is obtained an extremely reliable automatic closure or 
opening without any risk of wear or seizure of the control means and no 
maintenance is necessary. 
Such a device is of interest for example in the chemical industry for 
regulating the supply of boilers with liquid or gaseous fuel and for the 
safety of operation of four-stroke engines in the same way as two 
stroke-engines by ensuring the closure of the petrol supply in the event 
of a lack of oil or cooling liquid. 
This device may be modified in accordance with its applications, for 
example the tank 4 may be mounted on horizontal pipes, the float may be 
replaced by any other means for detecting the presence of the fluid in the 
tank and any other means for shifting the permanent magnet.