AU574451B2 - Pressure relief valve - Google Patents

Description

'4 1 AUSTRALIA Patents Act

DECLARATION FOR A PATENT APPLICATION

V INSTRUCTIONS Insert "Convention" In support of the convention application made by If appllcable nsert FULL name(s) of applicant(s) b? AU.M GMBH

nsert "of addltioa" (hereinafter called "applicant(s) for a patent (c) for an if applicabL Insert TITLE of invention entitled (d) Invention

PRESSURE LIMITING VALVE

(e)Insert FULL name(s) AND address(ea) of I/We RICHARD VOSS declarant(s) (See headnote*) NiFL Uff GMBH Gustav-P.inemann-StraBe 27 584o Schwerte, Federal Republic of Germany. do solemnly and sincerely declare as follows; t -1l,--I-am/-We-are-the--applicant(s): (or, in the case of an application by a body corporate) L name s) 1. I am/We are authorized to make this declaration on behalf of the applicant(s). Iac s -2-I-amAWe-are-the-actual inventor(s) of the invention. (or, where the applicant(s) is/are not the actual inventor(s)) 2. (t) RICHARD VOSS Gustav-Heinemann-StraBe 27 584o Schwerte Federal Republic of Germany cant(s) cant(s) derivedn) derive(s) is/are the actual inventor(s) of the invention and the facts upon which the applicant(s) from actual nventor(s) title inventor(s) is/are entitled to make the application are as follows: (See headnote') (g) The Applicant is the assignee of the inventor. as

(Note: Paragraphs3 and 4 apply only to Convention applications) S it Insert country, filing date, and 3. The basic application(s) for patent or similar protection on which the application is based basic applicant(s) for the/or EACH is/are identified by country, filing date, and basic applicant(s) as follows: basic application Federal Republic of Germany Federal Republic of Germany Federal 1 t 16th March, 1984 19th December, 1984 Republic t t Gat Grubenausbau GmbH Gat Grubenausbau GmbH of Germany Sl t It 6th Gat Grubenausbau GmbH 4. The basic application(s) referred to in paragraph 3 hereof was/were the first appucaion(s) made in a Convention country in respect of the invention the subject of the application.

Insert PLACE of signing Declared |M IfW t -i ll In Insert DATE of Dated AdI l2l4 14r 41 i. signing m Signature(s) of 4. .230.) declarant(s)

Note: No legalization or other witness required To: The Commissioner of Patents

P18/7/78 PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne, Australia

(12) PATENT ABRIDGMENT (11) Document No. AU-B-40063/85 (19) AUSTRALIAN PATENT OFFICE (10) Acceptance No. 574451

(54) Title PRESSURE RELIEF VALVE (51)4 International Patent Classification F16K 017/164 (21) Application No. :40063/85 (22) Application Date 18.03.85 Priority Data (31) Number (32) Date (33) Country 3409677 16.03.84 DE FEDERAL REPUBLIC OF GERMANY 3446210 19.12.84 DE FEDERAL REPUBLIC OF GERMANY (43) Publication Date 19.09.85 (44) Publication Date of Accepted Application 07.07.88 (71) Applicant RICHARD VOSE GRUBENAUSBAU GMBH; (72) Inventor RICHARD VOB (74) Attorney or Agent

(56) Prior Art Documents GB 2133121 GB 2018594 (57) Claim

1. A pressure relief valve in particular for hydraulic development of underground and tunnel construction comprising a valve housing having a circular chamber, an inlet means at one end and an outlet means at the other end, a valve piston which is displaceable in a bore in said inlet means and slidable through an 0-ring seal, said valve piston having openings which are closed in one position by said O-ring seal separating said vlave piston opening from said chamber and opening into said chamber in its open position, a spring located in said chamber, a retainer member in said chamber, betweer the spring and the valve piston, said spring urging said retainer member and valve piston to said closed position of the latter, said retainer member having a rim adjacent the surface of the chamber which rim is reduced in thickness on the valve piston side by a chamfered or rounded-off shape, said valve housing having a plurality of channels in the surface of the chamber parallel to the axis of the chamber which L

1:--~-1114_1~-1

(11) AU-B-40063/85 -2- 574451

provide passage of fluid from the piston side of the retainer member to the spring side, said chamber also having an abutment which limits the opening travel of said retainer member.

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O-ring can quite clearly be of smaller diameter or thickness.

IYY-I..^ i

AUSTRALIA

PatentsAct 57445 1 COMPLETE SPECIFICATION (ORIGINAL)

Class Int. Class Application Number: /g S'. Lodged:

t

S Complete Specification Lodged: Accepted: Published: r 'Priority e,

Related Art:

APPLICANT'S REF.: E 2571 Name(s) of Applicant(s): 'AT-GRUBENAUS-SB-A-GmbH- 'A, 'ickirJ Vos& rnbevjsaujbLcu n"s I

Address(es) of Applicant(s): Gustav-Heinemann-Stras se 27, 5840 Schwerte, Federal Republic of Germany.

Actual Inventor(s): Richard VoB.

Address for Service is: PHILLIPS, ORMONDE AND FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne, Australia, 3000 Complete Specification for the invention entitled:

"PRESSURE LIMITING VALVE"

The following statement is a full description of this invention, including the best method of performing it known to applicant(s):

P19/3/84

The invention relates to a pressure limiting valve,

particularly for hydraulic lining in underground mining

and tunnelling with a valve body, the inlet and outset

sides of which are isolated by a spring loaded valve piston

adapted for a degree of displacement which is limited by an

abutment and which is located in the piston bore associated

with the inlet side of the valve or, in the event of over-

load, are connected, the valve piston being biased by the valve spring via a valve spring retainer and, in the posi-

o' 10 tion of closure, being sealed by an 0-ring inserted in a groove. .*t

Such pressure limiting valves are used where the

occurrence of an overload might cause damage to the system,

t: particularly in the form of hydraulic props. In under-

15 ground mining and tunnelling, in longwork, the space

required for travelling, mine ventilation and haulage is

kept open by hydraulic props and by powered support assem-

bly units, preferably in the form of shield-type supports.

r According to the regulations laid down by mine inspecting

bodies, these and other hydraulic systems must be safe-

guarded by pressure limiting valves. In underground mining,

hazards are created in particular by rock bursts and sudden

settlement of the roof. The sudden bursts can so overload

the individual props or the entire system that lasting

damage or even destruction results. Therefore, very exact-

ing demands are made of pressure limiting valves.

However, the hitherto known pressure limiting valves

do not afford the necessary operational reliability by

;lrr i- -f-~7

3

virtue of their design and equipment. Known from DOS

33 14 837.6 is a pressure limiting valve in which a valve

piston disposed for displacement in a valve body is biased

by a spring having a flat characteristic. This spring is

described therein as a soft spring, with no further details

which would be necessary for design purposes. The axial

bore provided in the valve piston ends approximately at the

height of the radial bore and as a blind bore, and in the oo o position of closure the radial bores of the valve piston

10 are isolated by an O-ring from the outlet orifices of the

004,valve body. The O-ring is let into an annular groove and

S:0. is so constructed that it guarantees the necessary seal.

When the valve responds, the valve piston is displaced

beyond the O-ring against the force of the valve spring so

S: 15 that the pressurised medium can escape through lateral out- ra44

*04o* let orifices and the through bore in the setscrew. Such a pressure limiting valve if it is properly designed operates

within the acceptable tolerances. Certainly, correct design of the spring in particular is a prerequisite.

20 Nevertheless, difficulties arise because the pressurised

medium cannot be expelled quickly enough from the zone of

influence of the valve retaining spring, so that the accu-

racy of response suffers considerably. Another disadvantage

is that the cost of manufacture is burdened by the particu-

lar construction of the valve piston with the abutment edge

which ensures operation of the pressure limiting valve and

the overall construction of the valve. Also, there is no

clear teaching concerning the design of the valve spring.

-3a-

1 The invention is based on the problem of providing a

pressure limiting valve which permits of considerable throughput

for a short travel to guarantee a rapid and undisturbed

discharge of pressurised medium combined with a high reliability

of response.

According to one aspect of the present invention there is provided a pressure relief valve in particular for hydraulic development of underground and tunnel construction V* comprising a valve housing having a circular chamber, 10 an inlet means at one end and an outlet means at the Sto other end, a valve piston which is displaceable in a bore in said inlet means and slidable through an 0-ring seal, said valve piston having openings which are closed Se in one position and opening into said chamber in its open position, a spring located in said chamber, a retainer too: member in said chamber, between the spring and the valve

piston, said spring urging said retainer member and valve piston to the closed position of the latter, said retainer member having a rim adjacent the surface of the chamber So'* 20 which rim is reduced in thickness on the valve piston 'side S by a chamfered or rounded-off shape, said bore having a plurality of channels in the surface of the chamber parallel to the axis of the chamber which provide passage of fluid from the piston side of the retainer member to the spring side, said chamber also having an abutment 26 'which limits the opening travel of said retainer member.

15

valve bore 5 ensures that the valve piston 6 cannot slip

1 With such a type of pressure-limiting valve, one

fundamental problem of the known pressure-limiting valves is

solved. In the known types of pressure-limiting valves, it

is easy for the valve piston in the region of the radial bore

to be broken off. The webs which lie between the bores are

placed under tension when the pressure-limiting valve is

operated, because the valve piston is firmly held at its

lower end by the stop (detent) which is formed there. On

*O.t the other hand, in the case of the pressure-limiting valve in e t

1"io accordance with the invention, these webs are not placed under

tension but they are under pressure. This arises from the

s fact that the valve piston, during the operation of the

pressure-limiting valve, is pressed against the spring washer and this latter is then pressed against the storps (detents)

in the valve housing. Even in the end position, it is only

pressure forces which act on the webs ot the radial bores, so

that an essentially longer service Life is achieved. In

addition to this, such a type of pressure-limiting valve t operates advantageously in a trouble-free manner, that the

valve spring retainer is streamlined on its underside and in

that the inner wall of the valve body has throughflow passages

and /rt abutment which limits the travel of the valve spring

retainer.

An essential problem with the known pressure limiting valves is that the valve pistons 6 easily shear off in the

SCAt region of the radial bores 14, 15 so that the entire pressure limiting yalve becomes useless. The webs located between the radial bores 14, 15 are namely subjected to a tensile stress when the pressure limiting valves responds, because the valve piston 6 is held fast at its bottom end by an abutment which is constructed there.

In the case of the pressure limiting valve according

to the invention, on the other hand, these webs are not r tensile stressed but compression stressed. This results from the fact that when the pressure limiting valve responds,

the valve piston 6 presses against the valve spring retainer

8 and presses this then against the abutments 25 in the valve

piston 2. Also in the extreme postion, therefore, only

compressive forces act on the webs of the radial bores 14,

so that substantially longer working life can be achieved

with the pressure limiting valve. Such a pressure

3t

-4a- limiting valve operates advantageously without disturbance, since the pressurised medium is discharged in a way which is encouraged by the valve retaining spring and by the throughflow passages constructed on the inner wall of the valve body, the accuracy of response being substantially increased and improved by this even discharge of pressuri- sed medium. By virtue of the fact that the features which promote discharge of pressurised medium are provided in the *4 valve body itself, where there are also provided abutments to limit the movement of the valve retaining spring and thus also of the valve piston, the cost of manufacturing such t pressure limiting valves is substantially reduced. Another advantage is that the pressurised medium can flow into the large inner zone of the valve body without any substantial

S 15 changes of direction or flow-enhancingly constructed diver-

sions and can be flushed out of the valve body without

difficulty. By virtue of this fact, a throughput of

100 litres/min is achieved with a high security of response.

0 In order further to minimise the manufacturing costs, it

20 is according to the invention envisaged that the valve body

consist of a spring sleeve having at both ends a screwthread

and being at the inlet end sealed by a guide provided with

an external screwthread and a connecting member and out-

wardly by a setscrew biasing the valve spring. At the same

time, this also improves the reliability of response, since such a construction of the valve body or of the entire

pressure limiting valve simplifies manufacture and thus

also the monitoring of quality in such pressure limiting

I -6 This construction provides a unit type of design, CI valves.

since the guide with the connecting member can be adapted

to a particular instance of usage without the other parts

of the pressure limiting valve having to be changed. Thus,

such a pressure limiting valve can be used for any applica-

tion, in fact with in principle always the same basic compo-

nent parts. All that is necessary is to adapt individual

parts to the particular application. Spring flutter which 9 9I used to occur with such pressure limiting valves cannot 9t

4 11 10 arise since the diameter of the valve spring retainer is

greater than that of the valve spring. lt

For the streamlined construction of the valve spring

retainer, it is according to the invention envisaged to pro-

vide the valve spring retainer with a downwardly chamfered 4 4 444 edge. The edge can also be rounded off, in which case, as 1 4 &C$

described, the spring will rest on the retainer as a whole 4. #4 .4 4 9. or a corresponding distance will remain between the outer

edge of the spring and that of the valve spring retainer.

Furthermore, this gap makes it possible for the valve spring 9r

retainer to move up to the abutment constructed in the

inside wall of the valve body.

The controlled and accurate response of the pressure

limiting valve is assured when, as provided according to

the invention, the valve spring has such a spring constant

that the spring travel to be negotiated coincides with the

admissible increase in pressure. Thus, a man skilled in

the art is provided with a teaching as to how he must con-

struct the valve spring in order to guarantee reliable response of the pressure limiting valve. A spring with a flat characteristic or even a soft spring, on the other hand, is too inaccurate a designation and leaves the man skilled in the art with the task of ascertaining accurate specifications.

An optimum design of pressure limiting valve is one in

which the throughflow passages are constructed in the inner

wall of the spring sleeve below or at the level of the

0 o valve spring retainer and extend to above the abutment.

10 With throughflow passages which are so constructed, the

f pressurised medium as described can be controlled and so

guided and discharged that perfect operation of the pressure

limiting valve is guaranteed. The pressurised medium is

dispersed rapidly and without hindrance in that six through--

15 flow passages are provided and are disposed on the pitch 6f circle. Thus the manufacturing process is not excessively

t burdened by incorporation of the throughflow passages and

on the other hand a reliable abutment of the valve spring

4 retainer is achieved since in all six bearing points are

20 provided and are distributed over the circumference. The

spring is adjusted by the setscrew with a through bore in

the cover of the spring sleeve. This is secured by a tapered

notched pin.

Ingress of dirt into the spring space and thus a

possible adverse influencing of the response accuracy is

according to the invention prevented in that the enlarged

through bore has associated with it a spring loaded pin

*'l with a seat which is opened by the pressurised medium.

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The enlargement of the through bore is expedient in

guaranteeing the throughflow cross-section which is re-

quired for regular and rapid dispersal of pressurised

medium from the interior of the pressure limiting valve.

The spring loaded pin is thereby an effective additional

safeguard for the pressure limiting valve, the additional

fitment of which is readily possible even with existing

pressure limiting valves, since it is necessary only to of oi to a 0 0 change the setscrew with the corresponding additional com- P 9 10 ponents. 0

9O For applications where the spring is to be kept free from 000 *zoo the pressurised medium within the pressure limiting valve,

it is advantageous to fit between the valve spring

retainer and the guide with the valve i3ton an inter- 0 9*

15 mediate member with an intermediate piston sealed by an 0 0

O-ring and lateral outlet ports, corresponding screwthreads *I 9 being provided. Thus, the pressurised medium is dis- 9* charged laterally from the outlet ports without entering

00 9* the region of the spring at all. The intermediate piston

0 facilitates achievement of the necessary fitting accuracy

particularly since, in addition, it has the advantage that

by simple insertion of the intermediate member with the

intermediate piston, the previous component parts of the

pressure limiting valve can remain unchanged. All in all,

therefore, there is a further unit construction system

available which is eminently suited for underground use

by virtue of the concordance of selection.

To increase operational reliability still further, it is expedient for the intermediate piston to be constructed as a steel pin mounted in a friction reducing synthetic plas- tics bush. Particularly suitable for this is a Teflon coating or a Teflon bush in which the steel pin is pushed to create the necessary stability.

The pressure limiting valve explained permits of a

throughput of 100 1/min. This throughput rate can be

increased to 400 I/min if the throughflow areas of the axial

K*bore and of the radial bores of the valve piston, of the

10 bore in the spring sleeve which accommodates the valve spring tf

and of the through bore in the setscrew are equal to or

greater than the throughflow area of the given feed line.

In this way, all the pressurised medium which is supplied by

the feed line is, when the pressure limiting valve responds,

reliably passed through this so that cross-sectional varia-

tions or the like cannot have any or at least any effective

influence. The accuracy of such a pressure limiting valve

is thus particularly high. Such a pressure limiting valve

can be.used as an individual prop valve if the guide is

20 lengthened and adapted to the valve sleeves of individual

prop valves or housings of control units. The range of

t application of such pressure limiting valves is thus sub- stantially increased, and it is advantageous to be able to

resort to in each case the same construction principle.

Since thus the valves can pass through the same production line for all manner of applications, it is ensured that all

pressure limiting valves will achieve the same values, par-

ticularly in terms of safety.

An easier and more accurate fitting of the 0-ring is

possible if the piston bore is widened right through as far

as the 0-ring groove and is constructed to accommodate a

friction diminishing synthetic plastics tube, the inside

diameter of which is adapted to the outside diameter of the

valve piston. The large piston bore facilitates insertion

of the O-ring. A sufficiently reliable seat remains for the

0-ring because it is fixed on the one hand by the top edge

o 14 of the groove and on the other either by its bottom edge or

by the inserted synthetic plastics tube directly. The 9

pushed-in synthetic plastics tube is secured at the bottom 9 0

009 end against being unintentionally pushed out. Surprisingly,

therefore, it is possible to reduce the closure values once

again by around 50%, namely to 5 to 10 bars. Finally, the

0 9 1j minimal wear experienced by virtue of the pushed-in friction o *0 diminishing synthetic plastics tube is an advantage. Expe- 014 9 o 9* diently, a tube consisting of Teflon is used for this pur-

pose, particularly since this material, even if it is of 4 thin gauge, has the inherent rigidity which is advantageous O9 09149141 20 for insertion. 14 14~

Insertion of the 0-ring and its exact positioning are

substantially facilitated if, as provided by the invention,

the piston bore is widened out to the diameter of the groove

and if it is constructed so that it simultaneously co-

operates to form the groove. With this construction, the

0-ring is simply placed on the top end of the synthetic

plastics tube and inserted together with this latter. Since

the synthetic plastics tube is correspondingly accurately

dimensioned, thus also the exact positioning of the 0-ring can be guaranteed. Advantageous is the extremely simple insertion of the 0-ring, which substantially facilitates assembly work. Therefore, since jamming of the 0-ring is for practical purposes entirely out of the question, assembly can at the same time also be carried out substantially more reliably and in fact by less skilled personnel.

A further shortening of the necessary travel of the

valve piston is achieved if the 0-ring let into the groove

is of the same or slightly less thickness than the diameter

of the radial bores. In contrast to previous opinion, it

has surprisingly been found that it is entirely possible to use an 0-ring having a diameter which is less than the dia-

meter of the radial bores. Also the smaller diameter 0-ring

provides an accurate seal in the position of closure but can

advantageously be surmounted with a shorter travel by the

valve piston or by the radial bores in the valve piston.

By virtue of the shortening of the necessary travel of the valve piston to the point of leakage, the pressure limit-

ing valve responds even more quickly. In addition, assembly is substantially facilitated because an 0-ring having the

smallest possible thickness can be used. By reason of this

small thickness, it can naturally be handled and fitted

substantially more easily. Furthermore, if the groove is

correspondingly dimensioned, simplification of manufacture

of the guide or of the corresponding part of the pressure limiting valve is achieved. With larger valves, particu-

larly where the guide arrangement is increased, it is

possible to enlarge the valve piston and thus also the

bores which have to be accommodat~d therein. Here, the

0-ring can quite clearly be of smaller diameter or thickness.

Whereas in the case of a 5 am valve piston, the radial bores

provided therein should have a diameter of 1 to 1.2 mm and

the thickness of the O-ring should be 0.8 to 1mm, with a 10 mm

valve piston, the diameter of the radial bores can be 2.2 to

mm, and preferably 2.5 mm, while the thickness of the

O-ring should be 1.8 to 2 mn, and preferably be 2 mm.

To facilitate assembly, the invention furthermore

envisages the groove being longer than it is deep, preferably

being of twice the length. With such a groove, the 0-ring can advantageously be obliquely located, which substantially

facilitates assembly. The efficacy of the O-ring is surprising-

ly not adversely affected by the larger-sized groove. Instead, the valve piston passes reliably over the 0-ring so that a

perfect position of closure or opening is guaranteed. The tightness of the system can according to the invention be further enhanced if the groove has a rear wall

constructed to extend in the direction of the valve spring retainer and obliquely to the valve piston. Thus, the O-ring

which is displaced in the direction of the valve spring retainer by the pressurised fluid penetrating the groove and

by the movement of the valve piston is additionally deformed so that an even more reliable sealing surface is provided.

In the Figures 1 to 3, in each case, there is a rectangle indicated on the lower end of the valve piston 6,

in order to make it clear that, from this point on, there is

a narrowing of the valve bore 5 to ensure that the valve

piston cannot slip out of the bore towards the bottom.

The invention is characterised in particular in that a pressure limiting valve is provided which has a high. res-

DW -12- ponsz accw~acy and which,, Fay yixtue of its being constructed t4 t;

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-12'a- on the unit construction principle, can be used for the most widely diverse applications in what is in principle the same construction. So, particularly for the hydraulic units or props used in underground mining, a safeguard is provided which guarantees high operational safety. Another advantage is that the design chosen for the pressure lirait- ing valves is such that simple manufacture is possible.

Further details and advantages of the object of the i, 4 a 4r t .4,t invention will become evident from the ensuing description #4 I of the associated drawings which show preferred examples of

41 embodiment with the necessary details ani components. In

the drawings:

Fig. 1 is a longitudinal section through a pressure

limiting valve;

15 Fig. 2 is a cross-section through a valve body; I Ii

44 1 Fig. 3 is a pressure limiting valve in longitudinal ai F section, with a dust guard;

Fig. 4 is a pressure limiting valve in longitudinal 4 4; section, with an intermediate member;

i 20 Fig. 5 is a pressure limiting valve with a high through-

put capacity;

Fig. 6 is a pressure limiting valve envisaged for

incorporation into individual props;

Fig. 7 is a piston bore with a synthetic plastics /fubei

Fig. 8 is a piston bore with a synthetic plastics Iube;

Fig. 9 is an enlargement with an 0-ring, and

Fig,lO is a bottom part of a pressure limiting valve

with an 0-ring of smaller thickness.

The pressure limiting valve 1 shown in Fig. 1 has a

valve body 2, the input side 3 and output side 4 of which

are separated from each other by a valve piston 6 disposed

for displacement in the piston bore 5. The valve piston 6

is loaded by the valve spring 7 which is resting on the

valve spring retainer 8. The spring constant of this valve

spring 7 is so chosen that the spring travel to be nego-

tiated is in accordance with the admissible increase in a 4'

t pressure. This guarantees that in the event of an overload,

10 the valve spring can be quickly and reliably displaced by

the valve piston 6 and the valve spring retainer 8 suffi-

ciently that the pressurised medium can pass into the

interior of the valve body 2 and can spray out through the

bore 10 in the setscrew 9. The setscrew 9 is secured by a

notched pin 11 or a locking washer with Loctite.

The setscrew 9 is constructed on the inside similarly Sto the valve spring retainer 8 and is provided with a head

which at the same time carries the valve spring.

The valve piston 6 disposed in the piston bore 5 has,

distributed over its periphery, radial bores 14, 15 which communicate with the axial bore 16 and which permit

pressurised medium to flow through when the valve piston 6 is correspondingly extended. In the condition illustrated,

a seal is provided' by the O-ring 1.7 which is mounted in a

corresponding annular groove in the part which carries the

piston bore 5. In Figs. 1 to 3, a rectangleis shown in the

drawings as being at the bottom end of the valve piston 6,

to illustrate that from this point, a narrowing of the

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valv e bore 5 ensures that the valve piston 6 cannot slip

down wards and out of the bore.

In the embodiments illustrated in Fig. 1 and the other

drawings, the valve body 2 is constituted substantially by

the spring sleeve 20 which has at both ends a screwthread

21, 22 to accommodate the setscrew 9 at one end and the

guide 34 at the other. The spring sleeve 20 is provided

g,e with a large bore 23 into which the valve spring 7 can be

inserted, as illustrated. Incorporated on the inner wall *4, 10 24 of this spring sleeve 20 or the bore 23 and forming abut- 0**4

ments 25 are throughflow passages 26, 27 which facilitate

Ott an even and rapid passage of pressurised medium past the valve spring retainer 8. In the case of Fig. 1, the through-

flow passages 26 extend upwards into the region of the cover

15 28, so that the pressurised medium can with control be passed

in the direction of the setscrew 9 and through bore

In the region of the cover 28 of the spring sleeve

the valve spring 7 is braced on the spring sleeve and above

8 all on the setscrew 9. Disposed at the opposite end is the 20 valve spring retainer 8 on the supporting part 30 of which

the valve spring 7 rests fully. As illustrated, the valve

spring retainer has a larger diameter than the valve spring

7, so that the previously encountered valve spring rattle

is reliably prevented. The supporting part 50 of the valve

spring retainer 8 is of streamlined construction on the

underside 31 in that the rim 32 is chamfered off or flatten-

ed. The rim 32 can also be of arcuate construction, in

which case it must retain a form which ensures reliable application against the stop

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16

Through the external screwthread 35, the guide 34 can

be screwed into the spring sleeve 20. As shown, assembly

is facilitated if the valve spring 7 and the valve spring

retainer 8 can first be inserted or fitted into the spring

sleeve 20, fitment taking place through the guide 34, but

only after the first few turns of the screwthread have been

overcome. Thus, fitment or insertion of the guide 34 with

the valve piston 6 on the inside can be secured and an

exact fitment of all component parts achieved. Subsequent

j 10 tightening of the valve spring 7 is then effected via the

setscrew 9.

The guide 34 comprises a connection piece 36 which is

constructed according to the particular application involved.

This connecting piece 36 is, in the example illustrated,

constructed for a push-in connection, the 0-ring provided

i at the bottom end ensuring the necessary seal.

Fig. 2 shows a spring sleeve 20 in partial elevation and

in cross-section, and it is clear where and how the through-

flow passages 26 and 27 are located. In between are in each

20 case abutments 25 which effectively limit the travel of the

valve spring retainer 8.

f Fig. 3 shows an embodiment in which the throughbore

is sealed against dust by additions. For this purpose, a

pin 37 is provided which is pressed on the seat 38 by the

spring 39. This pin 37 is pressed out of the seat 38 when,

upon the valve piston 6 responding, pressurised medium

passes into the interior of the spring sleeve 20. The fact

that penetration of dust through the throughbore 10' is i

17

i effectively prevented means that the efficacy or accuracy

of response of the pressure limiting valve is additionally

enhanced.

In the case of the pressure limiting valve bhown in

Fig. 4, while the components spring sleeve 20, setscrew 9,

valve spring 7 and the other individual parts as well as the

guide 34 with the valve piston 6 are retained, a tight sea].

4t of the part of the housing which accommodates the valve 4 4a spring 7 is achieved by an interposed intermediate member

C* 40. This intermediate member 40 accommodates an inter-

mediate piston 41 which is sealed by an 0-ring 42. The

pressurised medium must and can only escape here through 4* S. I

I the lateral outlet ports 43, 46. I t

The intermediate member 40 has an external screwthread

44 and an internal screwthread 45 which are exactly adapted I 4(

to the corresponding screwthreads of the spring sleeve or guide 34. Thus, this intermediate member can be inser-

ted as a complete component between the existing or corres- i I pondingly constructed other parts and a completely effective It

pressure limiting valve 1 is available. As explained, such

a pressure limiting valve has an interior which is com- pletely sealed by pressurised medium and which accommodates

the valve spring 7 and possibly in this case, too, the set-

screw 9 may be provided with a sealing pin to prevent the

penetration of dust into the interior.

At its bottom end, the intermediate piston 41 has a shoulder 47 on which bears the head of the pin 37, the pin

head having a flattened face 48. The intermediate piston

I 18

41 is constituted by a steel pin 49 which is seated in a synthetic plastics sleeve

Fig. 5 shows a pressure limiting valve for a high

throughput capacity. The throughflow area of the axial bore

16 and of the radial bore 14, 15, like the throughflow area

of the large bore 23 in the spring sleeve 20 and the through-

flow bore 10 in the setscrew 9, are just as large or may

I even be larger than the throughflow area of the feed line %r 52. Upon comparison of Fig. 5 with the preceding figures, .9r;

**r 10 it is clear that the guide 34 is unaltered in its outside *9*1 *4 I *rl dimensions and has only a correspondingly enlarged piston

bore 5. To prevent the penetration of dust, the compara-

tively large through bore 10 is secured by a sealing pin 53.

This sealing pin 53 is biased by a spring which is initially i tensioned by the valve spring rutainer 54. This valve

9 spring retainer 54 has recesses 55, 56 in order to allow 99 the pressurised medium to emerge rapidly from the pressure

limiting valve 1. The sealing pin 53 is therefore tightly

seated on the seat 57 in the region of the through bore t i Also the features which are the object of the preceding

Claims are or can be used for expedient further develop-

ment of the embodiment shown in Fig.

The adapter 58 makes it possible for the guide 34

which has the conventional connection dimensions and the

correspondingly large volume valve body 2 or spring sleeve to be used. The adapter provides the necessary connec- tion between the two parts.

Fig. 6 finally shows a pressure limiting valve which can be used in individual prop valves or in control blocks.

To this end, it is necessary only to adapt the guide 34 to

the relevant conditions, the necessary seal being provided

by the external 0-ring 60. The upper part of the pressure

limiting valve, on the other hand, corresponds exactly to

that of the valve embodiments shown in Figs. 1 to 4, inclu-

ding the setscrew 9 with through bore 10, the valve spring

7, the spring sleeve 20 with the throughflow passages 26,

*r S 27 constructed on the inside and the abutment 25. Also the St C

valve spring retainer 8 has remained unaltered as has also 1#SE

.5,41+ the connection between guide 34 and spring sleeve 20. The

.4~ valve piston 6 with the axial bore 16 and the radial bores

14, 15 corresponds exactly to the valve piston 6 of the pre-

viously described embodiments.

l 15 Fig. 7 shows a synthetic plastics tube 62 inserted into

the correspondingly widened piston bore 5. This synthetic

plastics tube 62 which has the same outside and inside

diameter as the synthetic plastics bush 50, facilitates

2 fitment of the 0-ring 17 which in this way can be pushed 20 the bottom substantially more easily into the groove 1.8,

edge of which is, of course, partially dispensed with in

the lower zone. This edge is then augmented or replaced by

the top edge 68 of the synthetic plastics tube 62.

The inside diameter 64 of the synthetic plastics tube

62 corresponds to the outside diameter 63 of the valve

piston 6 so that this latter is reliably and easily guided

in the piston bore

The bottom end of the piston bore 5 is occluded by an

easily insertable recessed head screw 65 which secures the

synthetic plastics tube 62. Also this construction faci-

litates assembly since after insertion of the 0-ring 17 and

of the synthetic plastics tube 62, only the recessed head

screw 65 needs to be inserted and tightened up to position

accurately and reliably the parts which are particularly

important to the proper functioning of the pressure limiting

(valve 1. It will be appreciated that also the valve piston

10 6 is expediently inserted into the synthetic plastics tube

from below so that the 0-ring can be inserted into the

piston bore 5 even doubled at -he time of assembly.

Provided at the top end of the widened-out piston bore

is a web 69 to guarantee an accurate positioning of the

t 15 synthetic plastics tube 62 after insertion. Thus, the

bottom edge 67 of the groove 18 is retained although inser-

tion of the 0-ring 17 is somewhat more difficult in con-

sequence.

The inner bore 66 in the recessed head screw 65 corres-

20 ponds in diameter to the inside diameter 64 of the synthetic

plastics tube 62 or is larger as Fig. 8 shows. With a

larger piston bore, there is at the top end in the region

pJ of the bottom edge 67 an abutment 70 which, upon assembly,

indicates and establishes the optimum seating for the

synthetic plastics tube 62.

Fig. 9 shows the bottom end of a pressure limiting valve

1, particularly the guide 34. The drawing illustrates that

also with valve pistons 6 of small'diameter, here for example mm, it is nevertheless possible to use easy-to-fit O-rings

17, namely those which have a correspondingly smaller

thickness. The thickness of the O-rings 17 fitted in this

case is equal to or may even be less than that of the radial

bores 14,

Fig. 10 explains a facilitated assembly in the form of

a correspondingly large-sized groove 18', The length of

the groove 18' is preferably twice the diameter of the

O-ring 17. This O-ring 17 is shown by solid lines in the

installed position and by broken lines in the operating

position. The rear wall 71 of the groove 18' can extend at

a right-angle to the bottom edge 67 of the groove 18 or may

be at an angle thereto. Preferably, it is envisaged that

the rear wall 71 be constructed to extend obliquely to the

valve piston 6 in the direction of the valve spring

retainer 8.

Claims (4)

1. -21a

   The Claims defining the invention are as follows:

   i. A pressure relief valve in particular for hydraulic development of underground and tunnel construction comprising a valve housing having a circular chamber, an inlet means at one end and an outlet means at the other end, a valve piston which is displaceable in a bore in said inlet means and slidable through an O-ring seal, said valve piston having openings which are closed in one position by said O-ring seal separating said ,:0vlave piston opening from said chamber and opening into 4 t: said chamber in its open position, a spring located *fitin said chamber, a retainer member in said chamber, off* between the spring and the valve piston, said spring tOr urgifng said retainer member and valve piston to said closed position of the latter, said retainer member having a rim adjacent the surface of the chamber which rim is reduced in thickness on the valve piston side by a chamfered or rounded-off shape, said valve housing having a plurality of channels in the surface of the chamber parallel to the axis of the chamber which provide passage of fluid from the piston side of the retainer member to the spring side, said chamber also having an abutment which limits the opening travel of said retainer member.

   1

   1. A pressure relief valve in particular or hydraulic development of underground and tunnel co truction comprising a valve housing having a cir lar c'amber, an inlet means at one end and an outl means at the other end, a valve piston which is isplaceable in a bore in said inlet means and slj able through an 0-ring seal, said valve piston havin openings which are closed in one position and opening nto said chamber in its open position, a spring 1 cated in said chamber, a retainer member in said chmber etween the spring and the valve piston, said spring uging said retainer member and valve piston to the clos position of the latter, said retainer member having a im adjacent the surface of the chamber which rim is educed in thickness on the valve piston side by a c amfered or rounded-off shape, said bore having a plural'y of channels in the surface of the chamber parall to the axis of the chamber which provide passage of uid from the piston side of the retainer member to t spring side, said chamber also having an abutment c 1im
2. 2. A pressure relief valve according to Claim 1, '4 characterised in that the valve housing consists of a sleeve having at both ends screw thread and is closed at t the inlet end by a guide provided with an external screw thread and shaped as a push-in connecting piece for connection to a fluid pressure apparatus and by a setscrew S 30 at the outlet end engaged by the valve spring.
3. 3. A pressure relief valve according to Claim 1 or 2 characterised in that the channels extend from the level of the retainer member (in its position when the valve piston is in its closed position) to above the abutment.
4. 4. A pressure relief valve according to claim 1

   S characterised in that a spring loaded pin having a seat seals the outlet against ingress of dust.

   A pressure valve according to Claim 1 and Claim 2 characterised in that the throughflow areas of each of a bore in the valve piston radial bores constituting said openings in the valve piston the chamber which accommodates the valve spring and the outlet opening in the setscrew are equal to or greater than the through- flow area of a feed line connected to said bore in said inlet means.

   6. A pressure relief valve according to Claim i, characterised in that the piston bore is widened out as far as a groove in the piston bore for the O-ring and accommodates a friction-reducing synthetic plastics tube the inside diameter of which corresponds to the outside diameter of the vlave piston.

   7. A pressure relief valve according to Claim 6, characterised in that the piston bore is widened out to the diameter of the groove and is constructed to accommodate the synthetic plastics tube and to co-operate at the same time in forming the groove.

   8. A pressure relief valve according to Claim and 6, characterised in that the 0-ring let into the groove is of a thickness which is equal to or less than the diameter of the radial bores. 4 9. A pressure relief valve according to Claim i, characterised in that the O-ring is accommodated in a groove which is longer axially of the piston than it is radially.

   U o S 0. A pressure relief valve according to Claim 1 characterised in that the O-ring is accommodated in a groove which has rear wall constructed to extend obliquely

   I -24-

   with its narrow end nearer to the retainer member.

   11. A pressure relief valve as claimed in Claim 1 substantially as described with reference to any one of the examples shown in the accompanying drawings.

   DATED: 2nd November, 1987

   PHILLIPS ORMONDE FITZPATRICK Attorneys for:- GAT GRUBENAUSBAU GMBH u~u.Lnb s ueing ar ume DOttom enca or tne valve piston 6, to illustrate that from this point, a narrowing of the which

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