WO2002059509A2

WO2002059509A2 - Safety valve

Info

Publication number: WO2002059509A2
Application number: PCT/IB2002/000233
Authority: WO
Inventors: Gary Senior; Felix Bruno Gerber
Original assignee: Ism Inter (South Africa) Cc
Priority date: 2001-01-26
Filing date: 2002-01-28
Publication date: 2002-08-01
Also published as: ZA200103570B; WO2002059509A3; AU2002228268A1

Abstract

The invention provides for a safety valve (10) for regulating the flow of fluid in a hose connected to a pneumatic or hydraulic tool. The valve (10) includes a housing (12) which defines a primary chamber (16) having an inlet (28) and an outlet (30), and a secondary chamber (18) in fluid communication with the primary chamber (16). The secondary chamber (18) has an inlet in the form of eight apertures (36) leading from the primary chamber (16) to the secondary chamber (18) and an outlet in the form of eight apertures (38) leading from the secondary chamber to the primary chamber. A valve closure (14) is movable within the primary chamber (16) between an open position in which it is located between the secondary chamber inlet (36) and the secondary chamber outlet (38) for allowing air to flow from the primary chamber (16) to the secondary chamber (18) through the secondary chamber inlet (36) and from the secondary chamber (18) to the primary chamber (16) through the secondary chamber outlet (38), and a closed position in which it covers the secondary chamber outlet. The safety valve (10) also includes a coil spring (50) which is attached to the valve closure (14) for biasing the closure away from the closed position.

Description

SAFETY VALVE

BACKGROUND OF THE INVENTION

THIS invention relates to a safety valve for pneumatic or hydraulic equipment.

Conventional pneumatic tools generally are connected to a source of compressed air by means of synthetic rubber hoses. These hoses often are composed of two or more lengths of hose which are joined together with steel couplings. Typically, each coupling is connected to two lengths of hose by inserting a pair of coupling components into the ends of the hoses and fastening the components within the hose ends with clamps, and elastomeric rings are arranged within the coupling components to form a seal between these components when they are connected together to form the coupling.

In practice, if the coupling is not properly assembled and connected together the pressure inside the hose can cause the coupling components to separate, and if the coupling is not properly secured to the ends of the hoses the coupling components can be dislodged from the hose ends. Also, where the hose is exposed it can be cut or torn in use. Generally, if coupling components between two lengths of hose separate or if a length of hose is cut or torn, compressed air gushes out of the hose and causes it to thrash about uncontrollably, and this can lead to injuries for persons in the vicinity of the hose.

SUMMARY OF THE INVENTION

According to the invention there is provided a safety valve comprising:

a housing which defines:

a primary chamber having an inlet and an outlet, and

a secondary chamber in fluid communication with the primary chamber, the secondary chamber having an inlet leading from the primary chamber to the secondary chamber and an outlet leading from the secondary chamber to the primary chamber;

a valve closure which is movable within the primary chamber between an open position in which it is located between the secondary chamber inlet and the secondary chamber outlet for allowing fluid to flow from the primary chamber to the secondary chamber through the secondary chamber inlet and from the secondary chamber to the primary chamber through the secondary chamber outlet, and a closed position in which it covers the secondary chamber outlet; and

biasing means for biasing the valve closure away from the closed position.

In a preferred embodiment of the invention, the primary chamber extends along a central axis of the housing and the secondary chamber extends around at least a portion of the primary chamber. In this case, the primary chamber may be cylindrical in shape along at least a portion of its length and the secondary chamber may extend annularly around at least a portion of the length of the primary chamber.

Typically, the secondary chamber inlet comprises a plurality of apertures leading from the primary chamber to the secondary chamber, and the secondary chamber outlet comprises a plurality of apertures leading from the secondary chamber to the primary chamber.

In one arrangement, the valve closure comprises a generally cylindrical body which is slidable along at least a portion of the primary chamber.

The biasing means may comprise a coil spring which is fixed at one end relative to the housing and is fixed at the other end relative to the valve closure.

Preferably, the safety valve includes a mechanism for limiting the movement of the valve closure away from the closed position. In one embodiment the limiting mechanism comprises a collar around the coil spring which defines a rest position for the valve closure.

The housing may be composed of two or more components which are detachable from one another so as to facilitate the cleaning and maintenance of the valve. Typically, the valve is formed from aluminium, stainless steel or brass.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a cross-sectional view of a pneumatic safety valve according to the present invention in a rest condition;

Figure 2 shows a cross-sectional view similar to that of Figure 1 with the safety valve in an open condition;

Figure 3 shows a cross-sectional view of the pneumatic safety valve of the invention in a closed condition; and

Figure 4 shows a cross-sectional view of a hydraulic safety valve according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 of the drawings illustrates a pneumatic safety valve according to the present invention. The valve is designated generally with the reference numeral 10 and includes a housing 12 and a valve closure 14.

The housing is composed of three components 12A, 12B and 12C which together define a primary chamber 16 and a secondary chamber 18. In the illustrated embodiment, the component 12A includes an internal thread 20 which is arranged to engage an external thread 22 on the component 12C so that these components can be threadably connected to one another, and the component 12B is arranged to be sandwiched between the components 12A and 12C, as illustrated. The reference numerals 24 and 26 designate elastomeric O-rings which are arranged to from seals between the components 12A, 12B and 12C.

An inlet 28 leading into the primary chamber 16 carries an internal thread 32 for attaching this end of the valve 10 to a conventional quick-release coupling (not shown) and an outlet 30 leading from the chamber 16 carries an internal thread 34 for attaching this end of the valve to a quick-release coupling (also not shown). A secondary chamber inlet in the form of a plurality of apertures 36 leads from the primary chamber 16 to the secondary chamber 18, and a secondary chamber outlet in the form of a plurality of apertures 38 leads from the secondary chamber to the primary chamber, as shown. In this embodiment of the invention the valve 10 is designed to operate at a pressure of 700 kPa and includes eight inlet apertures 36 of 4 mm diameter and eight outlet apertures 38 of 5 mm diameter. It will be appreciated though that for different operating pressures the number and/or sizes of the inlet and outlet apertures may vary according to the application.

The valve closure 14 comprises a generally cylindrical body 40 which defines a cylindrical cavity 42 and an opening 44 in an end wall 46 thereof. A pin 48 carries a coil spring 50 which is attached at an opposite end to a pin 52. The pin 48 is fixed to the closure 14 and the pin 52 is connected to the component 12C so as to be fixed relative to the housing 12. A collar 54 extends around the spring 50, as illustrated, to define a rest position for the valve closure 14.

In practice, the valve 10 is connected to a synthetic rubber hose (not shown) leading to a pneumatic tool (also not shown) and is designed to regulate the flow of air from a source of compressed air (which is also not illustrated) to the tool. In this regard, the inlet end of the housing 12 is attached to the source of compressed air via the quick-release coupling and the outlet side of the housing is attached to the synthetic rubber hose via the quick-release coupling. When compressed air is fed to the valve 10, the initial pressure at the inlet side of the housing, i.e. in the cavity 42, displaces the valve closure 14 in the direction of the arrow A in Figure 1. As the closure is displaced in this direction, the apertures 36 are exposed and compressed air flows into the secondary chamber 18, through the apertures 38 and out of the outlet 30. The opening 44 in the end wall 46 regulates the displacement of the closure 14 along the chamber 16 so that before the closure reaches the apertures 38 the air pressures on the inlet side and the outlet side of the housing 12 are balanced and the valve closure 14 is held between the apertures 36 and 38, as shown in Figure 2. In this open condition of the safety valve 10, compressed air is allowed to flow through the valve to the pneumatic tool.

In the event that a coupling on the hose is broken or the hose is cut or torn so that compressed air gushes out of the hose, the sudden drop in pressure on the outlet side of the valve 10 causes the valve closure 14 to be driven across the chamber 16 into a closed position as illustrated in Figure 3. In this position, the apertures 38 are closed off by the valve closure 14 so that only a nominal amount of air is allowed through the valve 10. This then serves to prevent compressed air from gushing out of the hose and the consequent thrashing about of the hose which can cause injuries for persons in the vicinity of the hose. When the supply of compressed air to the safety valve 10 is cut off, the valve closure 14 is drawn back into the Figure 1 position by the coil spring 50.

Figure 4 of the accompanying drawings illustrates a cross-sectional view of a hydraulic safety valve according to the present invention. The valve 110 is similar in many respects to the pneumatic safety valve 10 described above and accordingly like reference numerals have been used to designate like features. However, the valve 110 includes two modifications for operating with hydraulic fluid as opposed to with air.

The first modification is an elastomeric O-ring 160 on the cylindrical body 40 which is arranged to form a seal between the valve closure 14 and the side wall of the chamber 16 as the valve closure slides within this chamber, in use. The second modification is an end wall 46 on the valve closure 14 which does not include an opening similar to the opening 44 in the valve closure of the first embodiment of the invention. The O-ring 160 and the omission of the opening 44 in the end wall 46 prevent hydraulic fluid from leaking from the valve 110 when the valve is in the closed condition.

Typically, the valve 110 is formed from stainless steel, but it will be appreciated that it could also be formed from various other materials, if desired.

Apart from the modifications described above, the valve 110 is similar in all other respects to the valve 10 and operates in a similar manner to that described above with reference to the pneumatic safety valve.

It should be appreciated that the components 12A, 12B and 12C can be detached from one another fairly easily, and that this facilitates the cleaning and maintenance of the valve by providing access to the inside of the chamber 18. It should also be appreciated that the valve 10 can be connected to and disconnected from an air line relatively easily and quickly.

Claims

1. A safety valve comprising:

a housing which defines:

a primary chamber having an inlet and an outlet, and

biasing means for biasing the valve closure away from the closed position.

2. A safety valve according to claim 1 , wherein the primary chamber extends along a central axis of the housing and the secondary chamber extends around at least a portion of the primary chamber.

3. A safety valve according to claim 2, wherein the primary chamber is cylindrical in shape along at least a portion of its length and the secondary chamber extends annularly around at least a portion of the length of the primary chamber.

4. A safety valve according to any one of the preceding claims, wherein the secondary chamber inlet comprises a plurality of apertures leading from the primary chamber to the secondary chamber, and the secondary chamber outlet comprises a plurality of apertures leading from the secondary chamber to the primary chamber.

5. A safety valve according to any one of the preceding claims, wherein the valve closure comprises a generally cylindrical body which is slidable along at least a portion of the primary chamber.

6. A safety valve according to any one of the preceding claims, wherein the biasing means comprises a coil spring which is fixed at one end relative to the housing and is fixed at the other end relative to the valve closure.

7. A safety valve according to any one of the preceding claims, including a mechanism for limiting the movement of the valve closure away from the closed position.

8. A safety valve according to claim 7, wherein the limiting mechanism comprises a collar around the coil spring which defines a rest position for the valve closure.

9. A safety valve according to any one of the preceding claims, wherein the housing is composed of two or more components which are detachable from one another.

10. A safety valve according to any one of the preceding claims, including an elastomeric seal on the valve closure for forming a seal between the valve closure and a side wall of the primary chamber.