WO2008083860A1

WO2008083860A1 - Valve for gas injector

Info

Publication number: WO2008083860A1
Application number: PCT/EP2007/057790
Authority: WO
Inventors: Vincenzo Baroni
Original assignee: A.E.B. S.R.L.
Priority date: 2007-01-12
Filing date: 2007-07-27
Publication date: 2008-07-17
Also published as: ITPR20070001A1

Abstract

The invention finds application in the field of gas injectors and more precisely relates to a gas shut-off system. A seal element (3) interposed between the moving part (11) and the stationary part (4) of the valve is not attached thereon but simply guidingly held in a seat (2), thereby apparently simplifying construction of the component; during operation of the injector (1), the element does not move from its position as the gas that presses thereon to flow out has a sufficient pressure to hold the element (3) in its seat. The seal element (3) is introduced in its seat (2) with a slight pressure; this slight pressure being as little as required to prevent the seal element (3) from coming out of the seat (2) when the latter is turned upside down.

Description

VALVE FOR GAS INJEKTOR

DESCRIPTION

This invention relates to a shutter valve for a gas injector. Background of the invention

Shutter systems are currently formed as follows:

A movable disk with a rubber part in the abutment area for shock absorption and improved tightness - Rubber on the stationary part of the abutment area, with the same purposes as above

0-ring on the stationary part, attached to the seat by particular OR locking arrangements . Various attachment arrangements may be provided for the latter system (as shown in the drawings that illustrate the prior art) :

- either a seat is formed in the metal with a shape complementary to the 0-ring, the latter being locked in the seat in such a manner as to be immovable therein;

- or a concave mechanical part is formed on the stationary element within the 0-ring, which holds the latter under tension, and provides fixed accommodation therefor . The object of this invention is to interpose a seal element between the moving part and the stationary part of the shutter valve, by providing an 0-ring on the stationary part, which is not attached thereon but simply guidingly held in a seat, thereby apparently simplifying construction of the component; during operation of the injector, the element does not move from its position as the gas that presses thereon to flow out has a sufficient pressure to hold the 0-ring in its seat .

A first advantage is that, under identical O-ring size conditions , a lower force is required to open the pipe. In classical systems, some material had to be provided within the O-ring to hold it fixed: considering the very small sizes of these components

(the inside diameter of the O-ring being typically of

2-3 millimeters) any additional thickness of the metal material used to lock the O-ring would be relevant, and often of the same order of magnitude as the radius ; therefore, the O-ring diameter has to be increased to obtain a gas outflow port of the same size.

The force that has to be overcome by the piston/disk to open the port corresponds to the sum of the force of the return spring and that required to overcome the differential pressure developed between the inside of the pipe having pressurized gas therein, and the outside with air at atmospheric pressure (a differential pressure of 1-2 Bar) .

As is known, pressure generates a force that is directly proportional to the area (the area of the atmospheric pressure environment being given by the diameter of the O-ring) ; if the diameter of the O-ring is even enlarged by 50-100% only, the force increases by 200-400% (area being proportional to the square of the diameter) .

Another advantage consists in a simpler construction as compared with traditional systems, in which the closing O-rings are locked in cavities formed in the metal (which involves mechanical processing problems) .

Finally, the following advantages result: reduced construction costs for the article, thanks to its much simpler shape;

- reduced tolerance-related design problems, with commercially available O-rings having well-defined shapes (unlike shutters that use rubber seals) ;

- simplified maintenance in case of damages to the seal element, the latter being simply replaceable with no locking elements to hinder O-ring removal/replacement: this further leads to reduced maintenance costs for the article.

These objects and advantages are achieved by the gas injector shutter valve of this invention, which is characterized by the annexed claims .

These and other features will be more apparent from the following description of a few embodiments , which are shown by way of example and without limitation in the accompanying drawings, in which:

- Figures 1 and 2 are two examples of the prior art that are currently used to form shutter systems for gas injectors;

- Figure 3 is a perspective view of the stationary element of the injector having a seat for accommodating the seal element of the injector of the invention;

- Figure 4 is a sectional view of the present injector.

Referring to Figures 1 and 2, two shut-off techniques as currently used in the art of gas injectors are shown, which namely contemplate the presence of a seal element 102, i.e. an 0-ring, attached to the stationary part 100, i.e. inserted in a cavity adapted to accommodate and lock said 0-ring; in Figure 1 , the metal is hollowed out to form a seat of a shape complementary to the 0-ring 102, which is thus locked in this seat in such a manner as to be immovable therein; in Figure 2, a concave mechanical part is formed within the O-ring 102, which holds the latter under tension, and provides fixed accommodation therefor. The moving part 101 will be obviously opened or closed by the pressure of the injected gas.

Unlike prior art, the present invention is based on an opposite principle, which means that the O-ring is free, or at the most slightly pressed into a seat 2 formed on the stationary part 4 of the valve shutter 1; such slight pressure being as little as required to prevent the seal element 3 from coming out of the seat when the latter is turned upside down.

Therefore the receiving seat 2 has the function of simply holding the seal element 3.

In the example of Figures 3 and 4 , numeral 1 designates the present injector, which comprises a shutter valve system composed of a moving part 11 (with a return valve 20) and a stationary part, designated by numeral 4 : the gas introduced in the chamber 10 can flow out by lifting the moving part 11 (thanks to the pressure that has built up in the chamber) , and passing through the seat 2 and the corresponding outlet port 15. Unlike the above mentioned prior art, no locking structures proper are formed and the O-ring is freely movable within its seat 2.

The above disclosure has already set forth the advantages of this "free ring" configuration, as well as the operating principle of the injector, in which the ring 3 is held in its position within the seat 2 by the pressure of the outflowing gas, which is sufficient to hold the O-ring in its seat. Hence, the seal element 3 cannot throttle the outlet port 15 by moving out of its seat, wherefore the outlet port will never be restricted and the gas flow will be unchanged. When the shutter valve is closed, with the moving part 11 pressed down against the element 3, due to the lack of pressure and the action of the spring 20, the system so configured holds the seal element 3 within the seat. The above system operates in any position of the injector body 1, i.e. even against the force of gravity, because gas pressure is sufficient to support the weight of the element 3.

To further ensure that the element 3 cannot come out of its seat, even when no gas is present, the stroke of the moving shutter member 11 is kept smaller than the size of the 0-ring 3: thus, even when no gas pressure is provided to hold the 0-ring in its seat, there is no possibility for the whole 0-ring to come out of its seat and to cause consequent malfunctioning of the injector 1.

Claims

1. A shutter valve for a gas injector (1) , of the type comprising a seal element between the moving part of the shutter valve and the stationary part, said seal being formed on the stationary part (4) , characterized in that said seal element (3) is guidingly held in its seat (2) formed on the stationary part (4) said seal element (3) being freely movable within said seat (2) .

2. A shutter valve for a gas injector as claimed in claim 1, characterized in that the seal element (3) is introduced in its seat (2) with a slight pressure; said slight pressure being as little as required to prevent the seal element (3) from coming out of the seat (2) when the latter is turned upside down.

3. A shutter valve for a gas injector (1) as claimed in claim 1 , characterized in that said seal element (3) is an 0-ring.

4. A shutter valve for a gas injector (1) as claimed in claim 1, characterized in that, during operation of the injector, the seal element (3) is held within the seat (2) by the pressure of the gas flowing thereon .

5. A shutter valve for a gas injector (1) as claimed in claim 1, characterized in that the stroke of the moving shutter member (11) is kept smaller than the size of the 0-ring (3) , so that the latter cannot come out of its seat, even when no gas is present.