Quick acting ball valve

A separating wall having a valve opening is disposed between a chamber holding a high pressure and a chamber holding a low pressure. The valve seat is closed by a ball acting as a valve body. For a quick opening of the valve, an actuating member imparts a lateral impact to the ball, thereby lifting the ball off the valve seat. Setting the ball back onto the valve seat is effected under the influence of the gas flow passing through the valve opening. The valve has extremely short switching times and allows for a high repetition frequency.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a quick acting ball valve. 
2. Description of the Related Art 
For specific applications, quick acting ball valves are needed which are 
able to allow a sudden passage of a fluid flow and which have a high 
switching rate. One such application is the time-of-flight spectroscopy in 
a molecular-ray-apparatus. In time-of-flight spectroscopy, a gas ray is 
released for a short time and the time the gas atoms take to travel a 
predetermined path is determined. The interval-like gas flow, interrupted 
by the quick acting valve, reduces the surplus gas and the necessary power 
of the pump. Presently, a gas ray is continuously introduced into the 
apparatus and released intermittently for the path by an interrupting 
valve. 
Valves are known in which a spring-biased bolt is pressed against a valve 
seat. In order to open the valve, the bolt can be lifted from the valve 
seat by means of a solenoid. Such valves have the disadvantage of a low 
repetition frequency. The masses of both the bolt and the valve body have 
to be commonly accelerated, which causes a retardation. 
It is the object of the present invention to provide a quick-action ball 
valve which can release a fluid flow in an impulse-like manner, which can 
be operated at a high repetition frequency and which has a high service 
life because of low wear. 
SUMMARY OF THE INVENTION 
In the ball valve of the present invention, the ball closes the opening, 
due to the pressure difference between the two chambers. In order to 
unblock the opening, a short lateral impact is imparted to the ball by the 
actuator, so that it clears the opening. The movement of the ball back 
onto the valve seat is effected by the fluid flow passing through the 
opening, only. The short switching times and the high repetition frequency 
result from the fact that only the mass of the ball has to be accelerated 
and that the actuator has no direct coupling to the ball. The actuating 
member of the actuator is accelerated before it hits the ball, so that 
only a short impact is exerted on the ball. The ball is not influenced by 
any mechanical parts, but it is freely movable and, in particular, it is 
not spring-biased. The ball not being in friction contact with other 
components, there is practically no friction wear. In order not to damage 
the ball and the actuator by the impacts, the impact surfaces are suitably 
made of hard metal. 
It is a particular advantage of the ball valve that its function is 
independent from its orientation, since the function does not use the 
influence of gravity. Setting back the ball is effected by the fluid flow, 
the influence of gravity being negligeable if the pressure difference is 
sufficiently large. 
The ball valve of the present invention is particularly suited for 
application in a molecular ray apparatus for time-of-flight spectroscopy. 
In this application, the valve is used for releasing and interrupting a 
gas flow. Further applications are the switching of fluids, e.g., in fuel 
injection systems of internal combustion engines. The valve is also suited 
for implementation at low temperatures for switching cryogenic fluids. 
Since the function of the valve is independent from temperature, it is 
also suited for applications involving high temperatures.

The drawing schematically shows a longitudinal section of the ball valve. 
The valve is located between two chambers 10,11 having different gas 
pressures. The chambers 10, 11 are separated by the separating wall 12. 
The separating wall 12 has an opening 13, the edge of which forms the 
valve seat 14. The gas pressure in the chamber 10 to which the valve seat 
14 faces, is considerably higher than in chamber 11. 
The ball 15 is located in chamber 10, which ball sits on valve seat 14 in 
the closed state, thus closing opening 13 gastightly. A chamber 18 
separated from chamber 10 by a separating wall 16 and having openings 17, 
serves to limit the movement of ball 15. Instead of separating wall 16, a 
cage may be provided that is arranged around opening 13, having the effect 
of limiting the range of movement of ball 15. 
The actuator 19 has a stationary solenoid 20 and a movable actuating member 
21. Upon excitation of solenoid 20, the bolt-like actuating member 21 is 
moved laterally towards ball 15, in order to roll ball 15 off valve seat 
14. A reset spring 22 acts upon actuating member 21, which pulls back the 
actuating member upon de-energization of solenoid 20. The impact of 
actuating member 21 is exerted parallel to separating wall 12, whereby 
ball 15 is hit exactly at its equator (parallel to separating wall 12). 
Once ball 15 has been lifted off seat 14, it is caught by the gas flow 
passing through opening 13, and driven back to the valve seat independent 
from the respective orientation of the valve. 
Preferably, a high-strength and non-abrasive material, in particular 
saphire or hard metal, is used for ball 15 and valve seat 14. Actuating 
member 21 or at least its front impact portion should preferably also 
consist of such material. 
The opening and closing time of the valve is influenced by the pressure 
difference between chambers 10 and 11, the mass of ball 15 and the 
diameter of bore 13. A ball of low mass and a strong gas flow at an open 
valve allow short opening and closing times. 
In the drawing, the actuating member 21 is illustrated in its rest 
position, i.e. with solenoid 20 de-energized. In this position, actuating 
member 21 is laterally spaced from ball 15. Upon excitation of solenoid 
20, actuating member 21 hits the resting ball 15 at a basic speed v.sub.o 
which is reached after termination of the acceleration phase of the 
actuating member. Since the mass of actuating member 21 is substantially 
larger than that of ball 15, ball 15 is abruptly removed from valve seat 
14 by the impact. This results in the desired quick opening behavior of 
the valve.