WO1989002557A1

WO1989002557A1 - Hydraulic pulse protection means

Info

Publication number: WO1989002557A1
Application number: PCT/AU1988/000369
Authority: WO
Inventors: John Duncan Mcnair
Original assignee: Vulcan Australia Limited
Priority date: 1987-09-21
Filing date: 1988-09-21
Publication date: 1989-03-23

Abstract

A device for protecting plumbing fittings from hydraulic over-pressure pulses or shock (water hammer) finds particular application in solenoid diaphragm valves used in automatic washing appliances of the type in which a diaphragm (14) is held against a seat (15) by a spring-loaded plunger (16), and is opened by energising a solenoid coil (18) to raise the plunger (16) against the opposing force of spring (17). The device comprises a spring (26) which holds a plug (27) against a seat (28) so blocking an orifice (29) against normal pressure difference between high and low pressure compartments (19, 20). When hydraulic shock pressure front enters the valve (10), it moves the plug (27) away from the seat (28) to allow a small volume of water from the high pressure compartment (19) to be expelled through the orifice (29) thus dissipating shock.

Description

HYDRAULIC PULSE PROTECTION MEANS BACKGROUND

This invention relates to protection of plumbing fittings and components from the damaging effects of hydraulic pressure shocks transmitted within a pressurised localised plumbing system. It further relates to this protection incorporated in a solenoid actuated diaphragm valve for protecting those fittings and components including the solenoid valve structure itself.

In a particular example it relates to the use of protection means incorporated in such solenoid diaphragm valves of the type used in automatic washing appliances. Solenoid valves in general are well known and are used for admitting water into appliances in a programmed sequence; these valves are of the type in which a diaphragm is closed against an opening by a spring of a strength sufficient to oppose the water supply pressure and is opened on demand by electromagnetic solenoid actuation opposing the spring force.

Previously, solenoid valves in washing appliances have generally given satisfactory service without the need for the protection means of this invention. The need for the invention has arisen and become more noticeable due to the increasing usage of quarter turn quick acting taps in plumbing systems. Such taps are readily able to be closed by a 90 degree rotation of the handle from full on to off n a fraction of a second and such a method of utilisation readily tends to cause hydraulic shock sometimes referred to as water hammer, that is a very high pressure short duration pulse or series of pulses, within the entire plumbing system of premises such as a domestic dwelling. Plumbing components which have proven to be prone to damage as induced by quick acting taps are flexible hoses connecting dishwashers or clothes washers to a water supply, solenoid valves in washing appliances, ceramic cartridges in the quick acting taps themselves, pressure limiting devices in appliances such as water heaters and flare joints not made to the highest plumbing standards, in the plumbing system itself. As well quick acti ng quarter turn manually operated taps introducing this water hammer problem, direct acting solenoid valves of the non-servo type are also known to cause water hammer. The proximity of the vulnerable component to the initiator of the pressure pulse has a bearing on the likelihood of damage.

Although it is common practice to connect a domestic washing appliance to the water supply by means of a flexible reinforced hose, the increasing popularity of quarter turn taps is being found increasingly associated with burst failures of such hoses. When used, the flexible hose is generally connected to a conventional domestic tap of the bib cock type having a screw threaded stem acting on a tap washer assembly which, because of its configuration, effectively operates as a non return. Such taps are very commonly left turned on most of the time, relying on the normally-closed solenoid valve to hold back water flow to the appliance at times of non-use. However when such a tap and hose combination are components of a plumbing system of premises in which high pressure pulses tend to be induced, the pulses pass into the tap body and readily bypass the washer, lifting it from the seat where it rests lightly under its own weight in an uprightly mounted tap. However by the time a return or rebound pulse tending to equilibrate the system pressure reaches the tap travelling back through the hose from the closed solenoid valve (at the other end of the hose) the washer has returned to its seat and the elevated pressure in the hose can not escape back through the tap. Thus successive pressure pulses flowing in the plumbing and passing through an open bib cock type tap into the flexible hose are capable of inflating the hose to extremely high pressures in incremental steps. Such pressures can in practice reach as high as 4000 to 5000 kilopascals and seriously shorten the life time of flexible hoses in the described environment.

Therefore a precaution adopted to overcome the problem ar sing with fail ng flexible hoses associated with the use of quarter turn quick acting taps is to connect washing appliances to the water supply mains by copper piping, for example. While copper pip ng is strong enough to withstand the pressures which can cause premature hose failure, it has transferred the problem to the next weakest elements n the system, including the solenoid valve which functions to admit water to the appliance. High pressure pulses involved in plumbing systems of premises are readily capable of damaging the body structure of the solenoid valves used in washing machines, which hitherto have been satifactory. Such valves have been developed over a period of time whereby they are now typically constructed of plastics materials.

Therefore the present invention has the aim of protecting such solenoid valves by the incorporat on of an over pressure relief means which serves to prevent the valve from being damaged by the pressure pulses experienced. This protection means has been found to be particularly effective in protecting other plumbing components as well as the valve itself in which it is incorporated. In view of the valve being associated with an appliance in which a provision already exists for draining of used washing liquid, the fact that the protection functions by enabling expulsion of a very small volume of compressed water as the method of absorbing the hydraulic pressure shocks, the incorporation of the protection in a solenoid valve directly communicating with such an appliance is very convenient. Otherwise, provision for disposing of an accumulation of expelled water would be necessary.

SUMMARY

The invention consists of an over-pressure protection means usable in conjunction with a solenoid actuated diaphragm valve i nterconnectable to a pressurised plumbing arrangement, for protecting against damage sustainable due to a pulse of hydraulically transmitted over-pressure when the valve is installed in the arrangement and closed, wherein the means is incorporated in the valve structure and comprises components and their interrelationship as described and claimed in the appended claim 1.

In a particularly preferred application of the invention it consists of an over-pressure protection means as claimed in claim 1 wherein the valve is installed in a washing appliance in a configuration as described and claimed in the appended claim 2. In a significant alternative embodiment the invention consists of an over-pressure protection means usable in conjunction with a solenoid actuated diaphragm valve i nterconnectable to a pressurised plumbing arrangement, for protecting against damage sustainable due to a pulse of hydraulically transmitted over-pressure when the valve is installed in the arrangement and closed, wherein the means is incorporated in the valve structure and comprises components and their nterrelationship as described and claimed in the appended claim 3.

In an occasionally convenient application of the invention it consists of an over-pressure protection means as described and claimed in claim 3 wherein the valve is installed in a washing appliance in a configuration as described and claimed in the appended claim 4.

In a further significant alternative embodiment the invention consists of an over-pressure protection means usable in conjunction with a solenoid actuated diaphragm valve i nterconnectable to a pressurised plumbing arrangement, for protecting against damage sustainable due to a pulse of hydraulically transmitted over-pressure when the valve is installed in the arrangement and closed, wherein the means is incorporated in the valve structure and comprises components and their interrelationship as described and claimed in the appended claim 5.

Preferably, in the above mentioned embodiments, the spring rates associated with the over pressure protection means are selected to ensure that the static or steady state pressure apply ng to the closed valve in use is contained up to a limit of approximately twice the normally expected operation pressure which would be within the expected ability of the valve to withstand without damage. The importance of this is that only pressure pulses of high instantaneous pressure with potential to cause damage are allowed past the pressure relief means, minor pressure excesses not thereby causing un ntentional and wasteful water leakage through the closed valve.

The invention is further described in terms of a particularly preferred embodiment by way of example, and variations thereof, with reference to the accompanying illustrations Figures 1 to 4, wherein:

DESCRIPTION OF THE DRAWINGS

Figure 1 is a cross-sectional elevation of a solenoid valve of a conventional design as used in washing appliances.

Figure 2 is a cross-sectional elevation of a diaphragm solenoid valve useable in a washing appliance and incorporating one embodiment of over-pressure protection means according to the invention.

Figure 3 is a cross-sectional elevation of a diaphragm solenoid valve useable in a washing appliance and incorporating a further embodiment of over-pressure protection means according to the invention.

Figure 4 is a cross-sectional elevation of a diaphragm solenoid valve useable in a washing appliance and incorporating a third embodiment of over-pressure protection means according to the invention.

DETAILED DESCRIPTION

With reference to Figure 1, a solenoid actuated diaphragm servo controlled valve 10 of conventional known type as fitted to a washing appliance is shown in cross-sectional elevation. The valve is of the type kept closed by spring force and opened by an electro-magnetic solenoid acting to overcome the spring force. The valve comprises a body 11, an inlet pipe 12, a flow regulator and filter combined 13 and a flexible diaphragm 14. The diaphragm is held against a seat 15 by a ferro- agnetic plunger 16 free to slide along a guide tube 24 and loaded in one direction by a spring 17. The valve 10 opens to admit flow past seat 15 when solenoid coil 18 is energised by switch and connection means (not shown) to exert a force on plunger 16 tending to compress spring 17. Flow of water from a high pressure compartment 19 interior of the valve body 11 past the seat 15 into a low pressure compartment 20 and thence to the washing appliance (not shown) by way of outlet pipe 21 takes place as a result of plunger 16 being raised by a current flow being switched to solenoid coil 18 allowing diaphragm 14 to displace upwardly due to a momentary unbalancing of the force acting on the diaphragm 14. Diaphragm 14 has balancing holes 22 through which water flows to fill the small enclosed volume of the valve above the diaphragm 14 including in the space enclosed by tube 24 which encloses sliding plunger 16 and spring 17. Diaphragm 14 has a central hole 9 blocked by a nose 8 of the plunger 16 when the valve is shut. As the valve is opened, momentary flow of water from above the diaphragm through hole 9 allows the upward water pressure on the diaphragm to exceed the downward sum of forces sufficiently long to allow initial flow to take place from high pressure compartment 19 to low pressure compartment 20. Valves of the type as illustrated in Figure 1 have shown an inability to withstand high pressure hydraulic pulses, in some cases failing by the body bursting at the join line 23 where the body 11 and diaphragm 14 meet and are joined to the upper portion of the valve body.

With reference to Figure 2 the valve basically similar to that illustrated in Figure 1, in Figure 2 shows the incorporation of the over-pressure protection means 25 according to the invention, which comprises a spring 26 which holds a oveable plug 27 against a seat 28 so blocking orifice 29 against normal pressure difference between high pressure compartment 19 and the low pressure compartment 20.

Spring 26 rate is selected such as to be capable of holding back approximately twice the anticipated maximum inlet pressure operational in the valve, thus ensuring that it does not leak under normal operational and relatively minor over-pressures.

The valve as illustrated in Figure 2 is protected from the tendency of incoming high pressure pulses to damage the valve body 11 by the response of moveable plug 27. When a pressure pulse, sometimes referred to as water hammer or hydraulic shock, travels into the valve via inlet pipe 12 past filter-regulator 13 the pressure front travels into the mouth of the orifice 29 and upon striking plug 27 momentarily moves it against the opposing force by spring 26, away from seat 28 and, as a result, a very small volume of water is expelled from the high pressure compartment 19 into low pressure compartment 20. This allows a sufficiently rapid fall in peak pressure otherwise experienced by the valve to protect the body 11 from the damage potential inherent when pressure pulses are generated within the water contained in the nterconnected plumbing. In absorbing the shock associated with the pulses, the over-pressure protection is also capable of protecting other vulnerable plumbing system components, including flexible connection hoses, ceramic cartridges in quick acting taps, pressure limiting devices in appliances such as water heaters and sub- standard quality flare joints in the plumbing system itself.

With reference to Figure 3 an alternative embodiment of an over^¬ pressure protection in a solenoid valve is illustrated in which the tube 24 guiding and containing plunger 16 is extended beyond the location or compression spring 17 above plunger 16. Above spring 17 is provided a piston 31, sealed around its concact with the bore of tube 24 by an "0" ring 35. Above piston 31 and contacting it is a pressure relief spring 32 retained at its upper end in position in tube 24 by stop 33 which may be adjustable for endwise location in the tube. Above piston 35 the tube is open to the surrounding atmosphere, by provision of a hole 34 through stop 33. The arrangement shown in Figure 3 functions by reason of the alteration in dynamic response of the diaphragm 14 (compared with the valve of Fig 1) allowing it to lift off its seat 15 enabling over-pressure pulses to escape from the high pressure compartment 19 of the valve past the seat 15. The alteration in dynamic response to that obtaining with the conventional valve as shown in Fig. 1 is due to the combined change in spring rate of the two springs 17 and 32 acting in series together with the viscous damping effect of the piston 35. Over-pressure pulses of high instantaneous pressure with potential to cause damage are allowed past the diaphragm to seat seal but longer duration relatively minor pressure excesses do not causing unintentional water leakage past the seal.

With reference to Figure 4 the valve 10 is provided with an over¬ pressure protection means 25 comparable in most respects with Figure 2. In Figure 4 however an over-pressure protection means 25 is located in the wall of the body 11 of the solenoid valve 10. Over-pressure pulses entering the high pressure compartment 19 of the valve 10 force plug 27 away from orifice 29 allowing small quantities of water to be expelled to outlet 41 and thence either into the interior of an appliance (not shown) in which the valve can be installed or, alternatively outlet 41 is connected by a pipe (not shown) to an inlet 42 to a drain 43 (illustrated schematically) externally of any such appliance.

Variations and modifications can be made to the above described preferred embodiment and the described variations thereto in ways which would nevertheless remain within the scope of the invention as claimed in the following claims.

USES AND ADVANTAGES

An example where the use of the protection means described is particularly relevant is where quarter turn quick acting taps are part of a localised, for example individual premises, plumbing system. Here the device protects system components such as a flexible hose connecting a washing appliance to the water supply, a solenoid valve in a washing appliance and a ceramic cartridge in a quick acting tap. An advantage of the device is that water expelled as a result of the absorption of hydraulic over-pressure shock is conveniently disposed of using existing drainage provisions in washing appliances in which exist a solenoid valve in which the protection is readily incorporated.

Claims

1. An over-pressure protection means usable in conjunction with a solenoid actuated diaphragm valve i nterconnectable to a pressurised plumbing arrangement, for protecting against damage sustainable due to a pulse of hydraulically transmitted over-pressure when the valve is installed in the arrangement and closed, wherein the means is incorporated in the valve structure and comprises a plug, an orifice in a wall of the valve dividing the valve into high pressure and low pressure compartments, the orifice being closeable by the plug under the influence of a spring; the plug, orifice and spring being configured such that the plug is moveable away from a position closing the hole in response to a pulse substantialy greater than normal operational pressure entering the high pressure compartment, thus to allow some liquid to be forced from the high pressure to the low pressure compartment, the spring being arranged to to reclose the orifice by the plug when no over-pressure pulses are being transmitted into the valve.

2. An over-pressure protection means as claimed in claim 1 wherein the valve is installed in a washing appliance and wherein the low pressure compartment of the valve communicates with the appliance such that a path for liquid expelled from the high pressure compartment of the valve as a consequence of performing the protection function is provided to utilise the already available washing liquid drainage provision of the appliance.

3. An over-pressure protection means usable in conjunction with a solenoid actuated diaphragm valve i nterconnectable to a pressurised plumbing arrangement, for protecting against damage sustainable due to a pulse of hydraulically transmitted over-pressure when the valve is installed in the arrangement and closed, wherein the means is incorporated in the valve structure and comprises a plug, an orifice in a wall of the valve creating an opening between a high pressure compartment of the valve and the exterior of the valve, the orifice being closeable by the plug under the influence of a spring; the plug, orifice and spring being configured such that the plug is moveable away from a position closing the orifice in response to a pulse substantialy greater than normal operational pressure entering the high pressure compartment, thus to allow some liquid to be forced from the high pressure compartment to the valve exterior, the spring being arranged to to reclose the orifice by the plug when no over-pressure pulses are being transmitted into the valve.

4. An over-pressure protection means as claimed in claim 3 wherein the valve is installed in a washing appliance and wherein a path is provided to enable liquid expelled from the high pressure compartment of the valve as a consequence of performing the protection function to connect to a drain separate from a drain provided for the wash ng liquid used in the operation of the appliance.

5. An over-pressure protection means usable in conjunction with a solenoid actuated diaphragm valve nterconnectable to a pressurised plumbing arrangement, for protecting against damage sustainable due to a pulse of hydraulically transmitted over-pressure when the valve is installed in the arrangement and closed, the diaphragm engaging a seat of the valve thereby dividing the valve when installed and closed into high pressure and low pressure compartments, wherein the means is incorporated in the valve structure and comprises a plunger slidably located in a guide tube and pushed by a first spring into contact with a low pressure side of the diaphragm, the other end of said first spring being in contact with a first side of a piston located in fluid tight contact with the interior of said guide tube and free to slide within it, the piston being pushed by a second spring in a direction towards the diaphragm; characterised in that the springs and piston are selected and configured such that the diaphragm is moveable away from a position engaging the seat in response to a pulse substantialy greater than normal operational pressure entering the high pressure compartment, thus to allow some liquid to be forced from the high pressure to the low pressure compartment, the spring being arranged to to reseat the diaphragm to close the valve when no over-pressure pulses are transmitted into the closed valve.

6. An over-pressure protection means substantially as hereinbefore described with reference to the accompanying drawings.