CA1243921A - Pressure limiting valve - Google Patents
Pressure limiting valveInfo
- Publication number
- CA1243921A CA1243921A CA000476616A CA476616A CA1243921A CA 1243921 A CA1243921 A CA 1243921A CA 000476616 A CA000476616 A CA 000476616A CA 476616 A CA476616 A CA 476616A CA 1243921 A CA1243921 A CA 1243921A
- Authority
- CA
- Canada
- Prior art keywords
- valve
- piston
- spring
- pressure limiting
- bore
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K17/00—Safety valves; Equalising valves, e.g. pressure relief valves
- F16K17/02—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side
- F16K17/04—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded
- F16K17/0446—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded with an obturating member having at least a component of their opening and closing motion not perpendicular to the closing faces
- F16K17/046—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded with an obturating member having at least a component of their opening and closing motion not perpendicular to the closing faces the valve being of the gate valve type or the sliding valve type
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K3/00—Gate valves or sliding valves, i.e. cut-off apparatus with closing members having a sliding movement along the seat for opening and closing
- F16K3/22—Gate valves or sliding valves, i.e. cut-off apparatus with closing members having a sliding movement along the seat for opening and closing with sealing faces shaped as surfaces of solids of revolution
- F16K3/24—Gate valves or sliding valves, i.e. cut-off apparatus with closing members having a sliding movement along the seat for opening and closing with sealing faces shaped as surfaces of solids of revolution with cylindrical valve members
- F16K3/26—Gate valves or sliding valves, i.e. cut-off apparatus with closing members having a sliding movement along the seat for opening and closing with sealing faces shaped as surfaces of solids of revolution with cylindrical valve members with fluid passages in the valve member
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Safety Valves (AREA)
- Actuator (AREA)
- Lift Valve (AREA)
Abstract
ABSTRACT
Pressure limiting valves, particularly for hydraulic lining in underground mining and tunnelling secure this lining against overload, the valve body having disposed within it a spring loaded valve piston which, when overloading occurs, allows a large quantity of the pressurised medium to emerge.
For this purpose, the underside of the valve spring retainer is of streamlined construction and provided in the valve body are throughflow passages which favour passage of the pressurised medium past the valve spring retainer. Move-ment of the valve spring retainer is confined by an abutment located in the throughflow passages in order to safeguard the valve spring. The O-ring in the groove has a smaller diameter than the radial bores. Thus, assembly is facilitated and it is at the same time ensured that the valve responds to short lengths of travel.
Pressure limiting valves, particularly for hydraulic lining in underground mining and tunnelling secure this lining against overload, the valve body having disposed within it a spring loaded valve piston which, when overloading occurs, allows a large quantity of the pressurised medium to emerge.
For this purpose, the underside of the valve spring retainer is of streamlined construction and provided in the valve body are throughflow passages which favour passage of the pressurised medium past the valve spring retainer. Move-ment of the valve spring retainer is confined by an abutment located in the throughflow passages in order to safeguard the valve spring. The O-ring in the groove has a smaller diameter than the radial bores. Thus, assembly is facilitated and it is at the same time ensured that the valve responds to short lengths of travel.
Description
The invention relates to a pressure li~iting Yalve, partioularly for hydraulic linlng in underground mining and tunnelling with a valve body, the inlet and outset sides of which are isolated by a spring loaded ~alve piston adapted for a degree of displacement which is limited by all abutment and which is located in the piston bore a~sociated with the inlet ~ide of the valve or, in the event of over~
load 9 are connec~ed 9 the valve pi~ton b0ing bia~ed by thP
valve sRring via a valve spring re~ainer and, î~ the po~-tion of closure, being sealed by an 0-ring inse~ted in a groové.
Such pres~ure limiting valve~ are used where the occurrence of an overload might cause dama&e to the systen~, particularly in the form of hydraulic prop~. ~n under-ground ~ining and tunnelling, in longwork, the space : required for travelling, mine ventilation and haulage i~
kept open by hydraulic props and by powered support a~se~-bly un~ts, preferably in the form of shield-type supports, According to the regulation~ laid down by mine lnspecting bodies, these and other hydraulic 9y9temg IllU~t be safe-guarded by pres~ure limiting valves. In underg~ound mini~, : hazsrds are created in particular by rock burst~ and sudden settlement of the roof. The sudden burst~ can 90 overload the indi~idual props or the entire system that lasting damage or even de~truction results~ Therefore D very ex~ot~-ing demands are made of pres~ure limiting Yalves.
However, the hi~herto known pressure limiting valves do not afford the necessary operational reliab~lit~ by 3~
virtue of ~heir design and equipment~ Known from DOS
33 14 837.6 is a pressure limiting valve in which a valYe piston disposed for displacement in a valve bod~ is biased by a spring having a flat characteristic. This ~pring is 5 described therein as a soft spring, with no further detail~ -which would be necessary for design purposes. The axial bore provlded in the valve piston ends approximately at the heigh~ of the radial bore and as a blind bore, and in the position of closure the radial bores of the valve piston are isolated by an O-ring from the outlPt orifices of the valve body. The 0-ring is let into an annular groove and iS 90 con~tructed that it guarantees the necessary seal.
When the valve responds, the valve piston i9 displaced beyond the 0-ring against the force of the valv~ spring so that the pressuri~ed medium can escapa through :Lateral out~
let orifices and the through bore in the setscrew. Such a pressure limiting valve if it is properly designed operate~
withln the acceptable tolerances. Certainly t correct design of the spring in particular i9 a prere~ui~ite.
Nevertheless, difficulties ari~e because th~ pres~urised medlum cannot be expelled quickly enough from the zone of influence of the valve retaining spring, so that the accu-racy of response suffers considerabl~. Another disadvantage i~ that the cost of manufact~lre iq burdened by the particu-lar con~truction of the valve piston with the abutmen~ edge which en~ures operation of thP pre~ure limiting valve and the overall constr~ction of the valYe~ Also, there iB no clear teaching concerning the de~ign of the valve ~pring.
., .. .
The invention is based on the problem of providing a pressure limit-ing valve which permits of considerable throughput for a short travel to guarantee a rapid and undisturbed discharge o pressurised medium combined with a high reliability of response.
According to the invention, the problem is resolved in that the valve spring retainer is streamlined on its underside and in that the inner wall o:f the valve body has throughflow passages and an abutment which limits the travel of the valve spring retainer.
With the pressure relief valve of the invention an important pro-blem in known pressure relief valves is solved. In the known pressure limit-ing or relief the valve pistons easily shear off in the region o~ tile raclial bores so that the entire valve becomes useless. The webs located between the radial bores are namely subjected to a tensile stress when the pressure limit-ing valve responds, because the valve piston is held fast at i-ts 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 tensile stressed but com-pression stressed. This results from the fact that when the pressure limit-lng valve responds, the valve piston presses against thevalvespring retainer
load 9 are connec~ed 9 the valve pi~ton b0ing bia~ed by thP
valve sRring via a valve spring re~ainer and, î~ the po~-tion of closure, being sealed by an 0-ring inse~ted in a groové.
Such pres~ure limiting valve~ are used where the occurrence of an overload might cause dama&e to the systen~, particularly in the form of hydraulic prop~. ~n under-ground ~ining and tunnelling, in longwork, the space : required for travelling, mine ventilation and haulage i~
kept open by hydraulic props and by powered support a~se~-bly un~ts, preferably in the form of shield-type supports, According to the regulation~ laid down by mine lnspecting bodies, these and other hydraulic 9y9temg IllU~t be safe-guarded by pres~ure limiting valves. In underg~ound mini~, : hazsrds are created in particular by rock burst~ and sudden settlement of the roof. The sudden burst~ can 90 overload the indi~idual props or the entire system that lasting damage or even de~truction results~ Therefore D very ex~ot~-ing demands are made of pres~ure limiting Yalves.
However, the hi~herto known pressure limiting valves do not afford the necessary operational reliab~lit~ by 3~
virtue of ~heir design and equipment~ Known from DOS
33 14 837.6 is a pressure limiting valve in which a valYe piston disposed for displacement in a valve bod~ is biased by a spring having a flat characteristic. This ~pring is 5 described therein as a soft spring, with no further detail~ -which would be necessary for design purposes. The axial bore provlded in the valve piston ends approximately at the heigh~ of the radial bore and as a blind bore, and in the position of closure the radial bores of the valve piston are isolated by an O-ring from the outlPt orifices of the valve body. The 0-ring is let into an annular groove and iS 90 con~tructed that it guarantees the necessary seal.
When the valve responds, the valve piston i9 displaced beyond the 0-ring against the force of the valv~ spring so that the pressuri~ed medium can escapa through :Lateral out~
let orifices and the through bore in the setscrew. Such a pressure limiting valve if it is properly designed operate~
withln the acceptable tolerances. Certainly t correct design of the spring in particular i9 a prere~ui~ite.
Nevertheless, difficulties ari~e because th~ pres~urised medlum cannot be expelled quickly enough from the zone of influence of the valve retaining spring, so that the accu-racy of response suffers considerabl~. Another disadvantage i~ that the cost of manufact~lre iq burdened by the particu-lar con~truction of the valve piston with the abutmen~ edge which en~ures operation of thP pre~ure limiting valve and the overall constr~ction of the valYe~ Also, there iB no clear teaching concerning the de~ign of the valve ~pring.
., .. .
The invention is based on the problem of providing a pressure limit-ing valve which permits of considerable throughput for a short travel to guarantee a rapid and undisturbed discharge o pressurised medium combined with a high reliability of response.
According to the invention, the problem is resolved in that the valve spring retainer is streamlined on its underside and in that the inner wall o:f the valve body has throughflow passages and an abutment which limits the travel of the valve spring retainer.
With the pressure relief valve of the invention an important pro-blem in known pressure relief valves is solved. In the known pressure limit-ing or relief the valve pistons easily shear off in the region o~ tile raclial bores so that the entire valve becomes useless. The webs located between the radial bores are namely subjected to a tensile stress when the pressure limit-ing valve responds, because the valve piston is held fast at i-ts 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 tensile stressed but com-pression stressed. This results from the fact that when the pressure limit-lng valve responds, the valve piston presses against thevalvespring retainer
2~ and presses this then agalnst the abutments in the valve housing. Also in the extreme position, therefore, only compressive forces act on the webs of the radial bores so that substantially longer working life can be achieved ~i.th the pressure limiting val-ve. Such a pressure ~L2~3~
limiting valve op~rates advantageo-lsly without disturbance, since the pressurised medium is discharged in a way which is encouraged by the valve retaining qpring and by the throll~hflow passages constructed on ~he inner wall of the valve body, the accuracy of response being sub~tantially increased and improved by this even di~charge of pressuri-sed medium. By virtue of the fact that the feature~ which pro~ote discharge of pressurised medium are provided in the valve body itselE, where there are also provided abutments to limit the movement of the Yalve retaining spring and thus also of the valve piston, the C03t of manufactllring such pressure limiting valves i9 sub~tantially reduced. Another advantage is that the pressuri~ed medium can :low into the large inner zone of the valve body without any substantial 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 9 a throughput of 100 litres/min i~ achieved with a high securl~y of re~ponse.
In order further to minimise the manufacturing costs, it i~ according to the invention envisaged that the valYe 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 an~ out-wardly by a setscrew biasing the Yalve springO At the sam~
: 25 time~ this al~o improves the reliability of response, since such a construction of the valve body or of the entire pressure limi~ing valve simplifie~ manufacture and thus ; also the monitoring of ~uality in ~uch pre~ure limiting ....
~2~3~
valve~. This construction provides a unit type of design~
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. Thu~, such a pressure limiting valve can be used for any applica-tion, in fact with in principle always the sa~e basic compo-nent parts. All that is necessary is to adapt individual parts ~o the particular application. Spring flutter which used to occur with such pressure limiting valves ~annot ari~e since the diameter of the valve spring retainer i9 greater than that of the valve spring.
For the streamlined construction of the valve spring retalner, it is according to the invention envisaged to pro-vide the valve spring retainer with a downwardly chamfered edge. The edge can also be rounded off 9 in which case~ as described~ ~he spring will rest on the retainer as a whola or a corresponding distance will remain between the outer edge of the spring and tha~ of the valve spring retainer.
Furthermore, thi~ gap makes it possible for the valve spring 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 sprlng 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 8S to how he must con-struct the valve sprlng in order to guarantee reliable ~3~
response of the pressure limiting valve~ A spring with a flat characteristic or even a soft spring, on the other hand~ oo inaccurate a designation and leave.s 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 passage~ are constructed in the inner wall of the ~pring sleeve below or at the level of the valv0 spring retainer and extend eo above the abutment.
Wlth throughflow passages which are BO constructed, the pressurised medium as described can be controlled and so guided and discharged that perfect operation of the pressure lim1ting valve i~ gl~aranteed. Th~ pressurlqed medium i9 dispersed rapidly and without hindrance in that qix through~
.
flow passage~ are provided and are disposed on the pitch circle. Thus the manufacturing process is no~ excessively burdened by incorporation of the throughflow passages and on the other hand a reliable abutment of the valve spring retainer is achieved since in all ~ix bearing point~ are provided and are dis~ributed over the circu~ference. The spring is adjusted by the setqcrew with a through bore in the cover of the spring sleeve. This i3 secured by a tapered notched pin.
Ingress of dirt into the ~pring space and ~hus a possible adverse influencing of the response accuracy is accordi~g to the invention prevented in that the enlarged thro~gh bore has associated with it a spring losded pin with a seat which i9 opened by the pressurised ~diumO
.~
The enlarge~ent of the th~ough bore is exped~ent in guaranteeing the throughflow cross-section which is re-quired for regular and rapid dispersal of pressurised medium Erom the interior o-f ~he 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 wi~h existing pressure limiting valves, since i~ is necessary only to change the setscrew with the corresponding additi~nal com-ponents.
For applications where the spring is to be kept free fromthe pressurised medium within the pressllre limiting valve, it is advantageous to fit between the valve sl)rillg retainer and the gulde with the valve piston an inter-mediate member with an intermediate piston sealed by an0-ring and lateral outlet ports, corresponding screwthreads being provided. Thus, the pressurised medium is dis-charged laterally from the outlet ports without entering the region oE the spring at all. The intermediate piston facilitate~ achievement of the necessary fitting accuracy particularly since, in addition, it has the ad~antage that by simple insertion of the intermediate member with the intermediate piston, the preYious component parts of the pressure limiting valve can remain unchanged. All in all, therefore, there is a further uni~ cons~ruction ~ystem aYailable which is e~inently suited for underground use by virtue of the concordance ~f selection.
To increase operational reliability still further, it is ~3~
expedient for the inte~mediate piston to be eonstructed 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 valYe explained permits o~ a throughput of 100 llmin. This ~hroughput rate can be increased to 400 l/min if the throughflow areas o~ the axia bore and of the radial bores of the valve piston 9 of the bore in the spring sleeve ~hich accommodates the valve spring and of the through bore in the setscrew are equal to or greater than the throughflow area of the gi~en feed line.
In this way, all the pressurised medium which is supplied by the feed line i9, 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 indiYidual prop valve if the guide is lengthened and adapted to the valv~ AleeYe~ of individual prop valves or housings of control units. The range of application o~ ~uch pressure limiting valves is thus sub-stantially increased, and i~ is advantageous to be able to resor~ to in each case the same construction principle~
Since thus the valves can pass through ~he qame praduction line for all manner of applications, it is en~ured that all pressure limiting valves ~ill achieve the ~ame valuesJ par-ticularly in terms of safety.
~3~
g An easier and more accurate fitting of the O-ri~g is possible if the piston bo~e is widened right through as far as the O-ring groove and is constructed to accom~odate 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 rernains for the O-ring because it is fixed on the one hand by the top edge of the groove and on the other either by its bottom edge or ~y the inserted synthetic plastics tube directly. The pushed-in 3ynthetic plastics tube is secured at the bottom end against being unintentionally pu~hed out. Surprisingly, thereforè, it is possible to reduce the closure ~alues once again by around 50%, namely to 5 to lO bars~ Finally, the minimal wear experienced by virtue of the pushed-in friction diminishing synthetic plastics tube is an advantageO ~xpe-diently, a tube CQnSisting of Teflon is used fo~ this pur-pose, particularly since this material, even if it is of thin gauge, has the inherent rigidity which is advantageous for insertion.
I~sertion of the O-ring and its exact positioning are ~ubstantially facilitated if, as provided by the invention, the piston bore is widened out to the diameter of the groo~e and if it i9 constructed so that it simultaneously co-~5 operates to fo~m the groo~e. Wi~h this constructi~n~ theO-ring is simply placed on the top end of the ~ynthetic plastics tube and inserted together with this latter. Since - the synthetic plastics tube is correspondingly accurately dimensioned, thus also the exact positioning of the O-rin~
:, ~2~3~
can be guaranteed. Ad~antageous is the extremely simple inser~ion of the 0-ring, which substantially facilitates assembly work. Therefore, since jamming of the 0-ring is for practical purposes entlrely out of the question, assemblg can at the same time also be carried out substantially more reliably and in fact by less skilled personnel.
A further Yhortening 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 con~rast to previous opinlon~ it has surprisingly been found that it is entirely possible to use an 0-ring having a diameter which is les~ than the dia-meter of the radial bores. Also the smaller diameter O~rin~
provides ~n 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 valYe piston.
By virtue of the shortening of the necessary travel of the valve piston to the point of lea~agel the pressure llmit~
ing valve responds even more quickly. In addition, assembly is ~ubstantially facilitated because an 0-ring having the s~allest 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 i~
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 arran~ement is increased, i~ is possible to enlarge the valve piston and thus also the bore~ which have to be accommodated therein. Here, the ;~
,, .
'` ' ' .t j ; ~ , O-ring can quite clearly be of smaller diameter or thickness~
Whereas in the case of a 5 mm valve piston, the radial bores provided therein should have a diameter of 1 to 1.? mm and ~he thickness of the O-ring should be 0.8 to 1 mm, with a 10 mm valve piston, the diameter of the radial bore3 can be 2.2 to 2.5 mm, and p}eferably 2.5 mm, while the thickne~s of the O-ring should be 1.8 to 2 mm, and preferably be 2 mmO
To facili~ate assembly, the invention further~ore envlsages the groove being longer than it i9 deep, prefer-ably being of twice the length. With such a groove, theO-ring can advantageously be obliquely located, which sub-stantially facilitates assembly. The efficacy of the O-ring ls surprisingly not adversely affected by the larger-sized groove. Instead, the valve piston passes reliably orer the O-ring so that a perfect position of clo~ure or opening i~
guaranteed.
The tightne s of the system can according to the inven-tiDn be further enhanced if the groove has a rear wall constructed to extend in the direction of the valve ~prin~
retainer and obliquely to the valve pis~on. Thu~, the 0-rlng which i~ displaced in the direction of the valve spring retainer by the pres3urised fluid penetrating the groove and by the ~ovement of the valve piston i9 additionally deformed so that an even more reliable sealing ~urf~ce i9 provided.
: The invention is characteri~ed in particular in that a : pres ure lim~ting valve i~ provided which hss a hlgh re~-ponse accuracy and which, by virtue o~ i~s being constructed .
limiting valve op~rates advantageo-lsly without disturbance, since the pressurised medium is discharged in a way which is encouraged by the valve retaining qpring and by the throll~hflow passages constructed on ~he inner wall of the valve body, the accuracy of response being sub~tantially increased and improved by this even di~charge of pressuri-sed medium. By virtue of the fact that the feature~ which pro~ote discharge of pressurised medium are provided in the valve body itselE, where there are also provided abutments to limit the movement of the Yalve retaining spring and thus also of the valve piston, the C03t of manufactllring such pressure limiting valves i9 sub~tantially reduced. Another advantage is that the pressuri~ed medium can :low into the large inner zone of the valve body without any substantial 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 9 a throughput of 100 litres/min i~ achieved with a high securl~y of re~ponse.
In order further to minimise the manufacturing costs, it i~ according to the invention envisaged that the valYe 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 an~ out-wardly by a setscrew biasing the Yalve springO At the sam~
: 25 time~ this al~o improves the reliability of response, since such a construction of the valve body or of the entire pressure limi~ing valve simplifie~ manufacture and thus ; also the monitoring of ~uality in ~uch pre~ure limiting ....
~2~3~
valve~. This construction provides a unit type of design~
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. Thu~, such a pressure limiting valve can be used for any applica-tion, in fact with in principle always the sa~e basic compo-nent parts. All that is necessary is to adapt individual parts ~o the particular application. Spring flutter which used to occur with such pressure limiting valves ~annot ari~e since the diameter of the valve spring retainer i9 greater than that of the valve spring.
For the streamlined construction of the valve spring retalner, it is according to the invention envisaged to pro-vide the valve spring retainer with a downwardly chamfered edge. The edge can also be rounded off 9 in which case~ as described~ ~he spring will rest on the retainer as a whola or a corresponding distance will remain between the outer edge of the spring and tha~ of the valve spring retainer.
Furthermore, thi~ gap makes it possible for the valve spring 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 sprlng 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 8S to how he must con-struct the valve sprlng in order to guarantee reliable ~3~
response of the pressure limiting valve~ A spring with a flat characteristic or even a soft spring, on the other hand~ oo inaccurate a designation and leave.s 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 passage~ are constructed in the inner wall of the ~pring sleeve below or at the level of the valv0 spring retainer and extend eo above the abutment.
Wlth throughflow passages which are BO constructed, the pressurised medium as described can be controlled and so guided and discharged that perfect operation of the pressure lim1ting valve i~ gl~aranteed. Th~ pressurlqed medium i9 dispersed rapidly and without hindrance in that qix through~
.
flow passage~ are provided and are disposed on the pitch circle. Thus the manufacturing process is no~ excessively burdened by incorporation of the throughflow passages and on the other hand a reliable abutment of the valve spring retainer is achieved since in all ~ix bearing point~ are provided and are dis~ributed over the circu~ference. The spring is adjusted by the setqcrew with a through bore in the cover of the spring sleeve. This i3 secured by a tapered notched pin.
Ingress of dirt into the ~pring space and ~hus a possible adverse influencing of the response accuracy is accordi~g to the invention prevented in that the enlarged thro~gh bore has associated with it a spring losded pin with a seat which i9 opened by the pressurised ~diumO
.~
The enlarge~ent of the th~ough bore is exped~ent in guaranteeing the throughflow cross-section which is re-quired for regular and rapid dispersal of pressurised medium Erom the interior o-f ~he 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 wi~h existing pressure limiting valves, since i~ is necessary only to change the setscrew with the corresponding additi~nal com-ponents.
For applications where the spring is to be kept free fromthe pressurised medium within the pressllre limiting valve, it is advantageous to fit between the valve sl)rillg retainer and the gulde with the valve piston an inter-mediate member with an intermediate piston sealed by an0-ring and lateral outlet ports, corresponding screwthreads being provided. Thus, the pressurised medium is dis-charged laterally from the outlet ports without entering the region oE the spring at all. The intermediate piston facilitate~ achievement of the necessary fitting accuracy particularly since, in addition, it has the ad~antage that by simple insertion of the intermediate member with the intermediate piston, the preYious component parts of the pressure limiting valve can remain unchanged. All in all, therefore, there is a further uni~ cons~ruction ~ystem aYailable which is e~inently suited for underground use by virtue of the concordance ~f selection.
To increase operational reliability still further, it is ~3~
expedient for the inte~mediate piston to be eonstructed 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 valYe explained permits o~ a throughput of 100 llmin. This ~hroughput rate can be increased to 400 l/min if the throughflow areas o~ the axia bore and of the radial bores of the valve piston 9 of the bore in the spring sleeve ~hich accommodates the valve spring and of the through bore in the setscrew are equal to or greater than the throughflow area of the gi~en feed line.
In this way, all the pressurised medium which is supplied by the feed line i9, 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 indiYidual prop valve if the guide is lengthened and adapted to the valv~ AleeYe~ of individual prop valves or housings of control units. The range of application o~ ~uch pressure limiting valves is thus sub-stantially increased, and i~ is advantageous to be able to resor~ to in each case the same construction principle~
Since thus the valves can pass through ~he qame praduction line for all manner of applications, it is en~ured that all pressure limiting valves ~ill achieve the ~ame valuesJ par-ticularly in terms of safety.
~3~
g An easier and more accurate fitting of the O-ri~g is possible if the piston bo~e is widened right through as far as the O-ring groove and is constructed to accom~odate 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 rernains for the O-ring because it is fixed on the one hand by the top edge of the groove and on the other either by its bottom edge or ~y the inserted synthetic plastics tube directly. The pushed-in 3ynthetic plastics tube is secured at the bottom end against being unintentionally pu~hed out. Surprisingly, thereforè, it is possible to reduce the closure ~alues once again by around 50%, namely to 5 to lO bars~ Finally, the minimal wear experienced by virtue of the pushed-in friction diminishing synthetic plastics tube is an advantageO ~xpe-diently, a tube CQnSisting of Teflon is used fo~ this pur-pose, particularly since this material, even if it is of thin gauge, has the inherent rigidity which is advantageous for insertion.
I~sertion of the O-ring and its exact positioning are ~ubstantially facilitated if, as provided by the invention, the piston bore is widened out to the diameter of the groo~e and if it i9 constructed so that it simultaneously co-~5 operates to fo~m the groo~e. Wi~h this constructi~n~ theO-ring is simply placed on the top end of the ~ynthetic plastics tube and inserted together with this latter. Since - the synthetic plastics tube is correspondingly accurately dimensioned, thus also the exact positioning of the O-rin~
:, ~2~3~
can be guaranteed. Ad~antageous is the extremely simple inser~ion of the 0-ring, which substantially facilitates assembly work. Therefore, since jamming of the 0-ring is for practical purposes entlrely out of the question, assemblg can at the same time also be carried out substantially more reliably and in fact by less skilled personnel.
A further Yhortening 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 con~rast to previous opinlon~ it has surprisingly been found that it is entirely possible to use an 0-ring having a diameter which is les~ than the dia-meter of the radial bores. Also the smaller diameter O~rin~
provides ~n 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 valYe piston.
By virtue of the shortening of the necessary travel of the valve piston to the point of lea~agel the pressure llmit~
ing valve responds even more quickly. In addition, assembly is ~ubstantially facilitated because an 0-ring having the s~allest 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 i~
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 arran~ement is increased, i~ is possible to enlarge the valve piston and thus also the bore~ which have to be accommodated therein. Here, the ;~
,, .
'` ' ' .t j ; ~ , O-ring can quite clearly be of smaller diameter or thickness~
Whereas in the case of a 5 mm valve piston, the radial bores provided therein should have a diameter of 1 to 1.? mm and ~he thickness of the O-ring should be 0.8 to 1 mm, with a 10 mm valve piston, the diameter of the radial bore3 can be 2.2 to 2.5 mm, and p}eferably 2.5 mm, while the thickne~s of the O-ring should be 1.8 to 2 mm, and preferably be 2 mmO
To facili~ate assembly, the invention further~ore envlsages the groove being longer than it i9 deep, prefer-ably being of twice the length. With such a groove, theO-ring can advantageously be obliquely located, which sub-stantially facilitates assembly. The efficacy of the O-ring ls surprisingly not adversely affected by the larger-sized groove. Instead, the valve piston passes reliably orer the O-ring so that a perfect position of clo~ure or opening i~
guaranteed.
The tightne s of the system can according to the inven-tiDn be further enhanced if the groove has a rear wall constructed to extend in the direction of the valve ~prin~
retainer and obliquely to the valve pis~on. Thu~, the 0-rlng which i~ displaced in the direction of the valve spring retainer by the pres3urised fluid penetrating the groove and by the ~ovement of the valve piston i9 additionally deformed so that an even more reliable sealing ~urf~ce i9 provided.
: The invention is characteri~ed in particular in that a : pres ure lim~ting valve i~ provided which hss a hlgh re~-ponse accuracy and which, by virtue o~ i~s being constructed .
3~
on the unit construction principle, can be used for the most widely di~erse applications in what is in principle the same con-struction. So, particularly for the hydraulic units or props used in underground mining~ a safeguard is provided which guaran-tees high operational safety. ~nother advantagc is that the de-sign chosen for the pressure limiting valves is such that simple manufacture is possible.
~ roadly, the invention may be stated as a fluid pres-sure limiting valve comprising a valve body having a circular chamber, an inlet means at one end and an outlet means at the other end, a valve piston slideably mounted in a bore in said inlet means and slideable through an O-ring seal, said valve piston having an axial bore communicating with radial bores which are closed in one position and which open into said chamber in its open position, a spring located in said chamber, a retainer mem-ber 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 which rim is reduced in thick-ness on the valve piston side by a chamfered or rounded-off shape, said chamber having a plurality of channels formed in a wall of the valve body, which channels extend parallel to the axis of the chamber and 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.
Further details and ad~antages of the object of the ,~
~L~43~
-12a- 27026~12 invention wlll become evident from the ensuing description of the associated drawings which show preferred examples of embodiment with the necessary details and components. In the drawings:
Fig. 1 is a lonyitudinal section through a pressure limiting valve;
Fig. 2 is a cross-section through a valve body;
Fig. 3 is a pressure limiting valve in longitudinal section, with a dust guard;
Fig. 4 is a pressure limiting valve in longitudinal section r with an intermediate member;
Fig. 5 is a pressure limiting valve with a high through-put capacity;
Fig. 6 is a pressure limiting valve envisaged for incorporation into indi~idual props;
Fig. 7 is a piston bore with a synthetic plastics tube;
Fig. 8 is a piston bore with a synthetic plastics tube;
Fig. 9 is an enlargement with an O-ring, and Fig. 10 is a bottom part of a pressure limiting valve .ith an J-rin~ of smaller ~bickness.
~3~
The pressure limiting valve 1 ~hown in Fig. 1 has a valve body ~ 7 the input side 3 and output side 4 of which are separa~ed from each other by a valve pi~ton 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 80 The spring cons~ant of ~his valve Rpring 7 is so chosen that the spring travel to be nego-tiated is in accordance with the admissible increa~e in pressureO This guarantees that in the event of an overload, the valve spring can be quickly and reliably dl~placed by ~he valve pi~tsn 6 and ~he valve spring retainer 8 suffi-ciently that the pressurised medium can pass in~o the interior of the valve body 2 and can spray out throu~h the bore 10 in the ~etscrew 9. The setscrew ~ iq secured by a notched pin 11 or a locking washer with Loctite~
The setscrew 9 is constructed on the in~ide similarly to the val~e spring retainer 8 and is provlded with a head which at the same time carries the vslve ~pring.
The valve piston 6 disposed in the piston bore 5 ha~, di~tributed over its periphery, radial bores 14~ 15 which communicate with the axial bore 16 and wllich permit pressurised medlum to flow through when the ~aIve pi9ton 6 i~ correspondingly extended. In the condit:ion illustrated, a seal is provided by the 0-ring 17 which is mounted in a corresponaing annular groove in the part ~hich carries the pi~ton bore 5. In Figs. 1 to 3, a rectangleis shown in the drawings as being at the bottom end o ~he valve pi~ton 6 t to illustrate that from this point, a na~row~ng o~ the valve bore 5 ensures that the valve piston 6 cannot 51ip downwards and out of the bore.
In the embodiments illustrated in Fig. 1 and the other drawings, the ~alve 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 with a large bore 23 into which the valve spring 7 can ~e inserted, as illustrated. Incorporated on the inner wall 10 24 of this spring sleeve 20 or the bore 23 and forming abut~
ments 25 are throughflow passages 26, 27 which facilitate 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 28, so that the pressurised medium can with control be passed in the direction of the setscrew 9 and through ~ore ~0.
In the region of the cover 28 of the spring sleeve 20, the valve spring 7 is braced on the spring sleeve and above all on the setscrew 9. Disposed at the opposite end i~ the 2G valve spring retainçr 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 rat~.le is reliably prevented. The supporting part 50~of the valve spring retainer 8 is of streamlined construction on the underside 31 in that the ri~ 32 is chamfered o~ or flatten-ed. The rim 32 can also be of arcuate construction, in which case it must retain a form which ensures reliable application agalnst the stop 25.
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.
~2~3~
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 31eeve 20, fitment taking place ~hrough the guide 34, but only after the first few turns of ~he 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 par~s achieved. Subsequent tightening of the valve spring 7 is then effected ~ia the setscrew 9.
The guide 34 comprises a connection piece 36 which is constructed according to the particular applicatlon involved.
This connecting piece 36 is, in the exa~ple illustrated, , con3tructed for a push-in connection, the 0-ring pro~ided at the bottom end ensuring the neces~ary seal.
Fig. 2 show~ a spring sleeve 20 in partial elevation and in cros~ection, and it is clear where and how the through-flow passages 26 and 27 are located. In between ~re in each case abutments 25 which effectively limit the travel of the valve spring retainer 8.
Fig. 3 shows an embodiment in whlch the throughbore 10 is ~ealed against dust by additions. For this purpose, a pin 37 is provided which is pressed on the 3eat 38 by the 25 spring 39. This pin 37 is pressed out of the seat 38 when, upon the valve piston 6 responding 9 pressur~sed medium passes into the interior of the spring sleeve 20. The fact that pene~ration of dust through the throughbore lOI i9 , ., ~3~
effectively prevented means that the efficacy or accurac.y of response of ~he pressure limiting valve is additionally enhanced.
In ~he case of ~he pressure limiting valve ~hown in Fip. 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 seal of the part of the housing which acco~modates the valve spring 7 is achieved by an interposed intermediate mem~er 40, This intermediate member 40 accommodates an inter-10 mediate piston 41 which is sealed by an 0-ring 42. The pressurised medium must and can only escape here through the lateral outlet ports 43, 46.
The intermediate member 40 has an external screwthread 44 and an internal screwthread 45 which are exactly adap-ted to the corresponding screwthreads of thP spring sleeve 20 or guide 34. Thus~ this intermediate member can be inser-ted as a complete component between the existing or corres-pondingly constructed other parts and a completely effeetive pre3sure limiting valve 1 is avail~ble. As explained, such a pressure limiting valve has an interior which i3 com-- pletely sealed by pressurised medium snd 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 intermedlate piston 41 has a shoulder 47 on which bears the head of the pin 37, the pin head havlng a flattened face 48. ~he intermediate pi~ton ~2~3~
~ 17 41 is con~tituted by a steel pin 49 which is seated in a synthe~ic plastics sleeve 50.
Fig. 5 shows a pressure limitlng valYe 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 ~0 and ~he through-flow bore 10 in ~he setscrew 9 9 are just a~ large or may even be larger than the throughflQw area of the feed line 52. Upon compari~on of Fign 5 with the preoeding f-lgures, it is clear-that the guide 34 is unaltered i~ it~ outside dimensions and has only a corre3pondingly enlarged piston bore 5. To prevent the penetration of dust~ the compara-tively large through bore 10 i~ secured by ~ sealing pin 53~
This sealing pin 53 is biased by a spring which is ini.tially . ~
tensioned by the valve spring retainer 54, This valve spring retainer 54 has reces~e~ 55, 56 in order to 8110w the pressurised medium to emerge rapidly from the pressure Iimiting valve 1. The sealing pin 53 is therefore tightly seated on the seat 57 in the region of the through bore 10 : 20 Also the features which are the object of the preceding Claimq are or can be used for expedient further develop-ment of th~ embodiment shown in Fig. 5.
The adapter 58 makes it possible for the guide 34 which has the conventionaI connection di~ensions and the correspondingly large volume valve body 2 or spring ~leeve 20 to be used. The adapter provides the necessary connec-tion between the two parts.
Fig~ 6 finally shows a pressure limiting valve which :,, ~2~3~
can be used in i~dividual prop val~es or in cont~ol 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 pres~ure li~iting valve, on the other hand, corresponds exactly to that of the ~alve 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 passagss 26, 27 constructed on the inside and ths abutment 25. Also the valve spring retainer 8 has remained unaltered as has also the connection between guide 34 and spring sleeve 20. The 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 de~cribed embodiments.
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Fig. 7 shows a synthetic plastics tube 62 -inserted lntQ
the correspondingly widened piston bore S. This synthetic plastics tube 62 which has the same outside and inside diameter as the synthetic plastic~ bush 50, facilitates fitment of the 0-ring 17 which in this way can be pushed ~ubstantially more easily into the groove 18, the bo~tom edge of which is, of coursel partially dispensed with in the lower zo~e. This edge i9 then augmented or replaced by the top edge 68 of the synthetic pla5tic5 tube 62.
The inside diameter 64 of the synthetic plastics tube 62 corresponds to the outside diameter 63 of the val~e piston 6 so that this latter is reliably and easlly guided in the piston bore S.
.
, 3~
_ 19 -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 Yalve piston 6 is expediently inserted into the synthetic plastics ~ube from below so that the 0-ring can be inserted into the piston bore 5 even doubled at the time of assembly.
Provided at the top end of the widened out piston bore 5 is a web 69 to guarantee an accurate positioning of the 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-ponds in diameter to the inside diameter 64 of the syntheticplastics tube 62 or is larger as Fig~ 8 shows. With a larger piston bore 3 there is at the top end in the region of the bottom ed~e 67 an abutment 70 which, upon assembly, indicates and establishes the optimum seating for the - 25 synthetic plastics tube 62.
Fig. 9 shows the bottom end of a pressure ~imiting Yalve 1, particularly the guide 34. The drawing illustrates that also wi~h valve pistons 6 of small-diameter, here for example ~ ., ~3~
5 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 Q-rings 17 fitted în this case is equal to or may even be less than that of the radial bores 14, 15, 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 0-ring 17 is shown by solid lin23 in the IO 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 en~lsaged that the rear wall 71 be constructed to extend obliquely to the . .
: 15 valve piston 6 in the direction of the valve spring retainer 8.
: :
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.
. ~-
on the unit construction principle, can be used for the most widely di~erse applications in what is in principle the same con-struction. So, particularly for the hydraulic units or props used in underground mining~ a safeguard is provided which guaran-tees high operational safety. ~nother advantagc is that the de-sign chosen for the pressure limiting valves is such that simple manufacture is possible.
~ roadly, the invention may be stated as a fluid pres-sure limiting valve comprising a valve body having a circular chamber, an inlet means at one end and an outlet means at the other end, a valve piston slideably mounted in a bore in said inlet means and slideable through an O-ring seal, said valve piston having an axial bore communicating with radial bores which are closed in one position and which open into said chamber in its open position, a spring located in said chamber, a retainer mem-ber 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 which rim is reduced in thick-ness on the valve piston side by a chamfered or rounded-off shape, said chamber having a plurality of channels formed in a wall of the valve body, which channels extend parallel to the axis of the chamber and 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.
Further details and ad~antages of the object of the ,~
~L~43~
-12a- 27026~12 invention wlll become evident from the ensuing description of the associated drawings which show preferred examples of embodiment with the necessary details and components. In the drawings:
Fig. 1 is a lonyitudinal section through a pressure limiting valve;
Fig. 2 is a cross-section through a valve body;
Fig. 3 is a pressure limiting valve in longitudinal section, with a dust guard;
Fig. 4 is a pressure limiting valve in longitudinal section r with an intermediate member;
Fig. 5 is a pressure limiting valve with a high through-put capacity;
Fig. 6 is a pressure limiting valve envisaged for incorporation into indi~idual props;
Fig. 7 is a piston bore with a synthetic plastics tube;
Fig. 8 is a piston bore with a synthetic plastics tube;
Fig. 9 is an enlargement with an O-ring, and Fig. 10 is a bottom part of a pressure limiting valve .ith an J-rin~ of smaller ~bickness.
~3~
The pressure limiting valve 1 ~hown in Fig. 1 has a valve body ~ 7 the input side 3 and output side 4 of which are separa~ed from each other by a valve pi~ton 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 80 The spring cons~ant of ~his valve Rpring 7 is so chosen that the spring travel to be nego-tiated is in accordance with the admissible increa~e in pressureO This guarantees that in the event of an overload, the valve spring can be quickly and reliably dl~placed by ~he valve pi~tsn 6 and ~he valve spring retainer 8 suffi-ciently that the pressurised medium can pass in~o the interior of the valve body 2 and can spray out throu~h the bore 10 in the ~etscrew 9. The setscrew ~ iq secured by a notched pin 11 or a locking washer with Loctite~
The setscrew 9 is constructed on the in~ide similarly to the val~e spring retainer 8 and is provlded with a head which at the same time carries the vslve ~pring.
The valve piston 6 disposed in the piston bore 5 ha~, di~tributed over its periphery, radial bores 14~ 15 which communicate with the axial bore 16 and wllich permit pressurised medlum to flow through when the ~aIve pi9ton 6 i~ correspondingly extended. In the condit:ion illustrated, a seal is provided by the 0-ring 17 which is mounted in a corresponaing annular groove in the part ~hich carries the pi~ton bore 5. In Figs. 1 to 3, a rectangleis shown in the drawings as being at the bottom end o ~he valve pi~ton 6 t to illustrate that from this point, a na~row~ng o~ the valve bore 5 ensures that the valve piston 6 cannot 51ip downwards and out of the bore.
In the embodiments illustrated in Fig. 1 and the other drawings, the ~alve 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 with a large bore 23 into which the valve spring 7 can ~e inserted, as illustrated. Incorporated on the inner wall 10 24 of this spring sleeve 20 or the bore 23 and forming abut~
ments 25 are throughflow passages 26, 27 which facilitate 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 28, so that the pressurised medium can with control be passed in the direction of the setscrew 9 and through ~ore ~0.
In the region of the cover 28 of the spring sleeve 20, the valve spring 7 is braced on the spring sleeve and above all on the setscrew 9. Disposed at the opposite end i~ the 2G valve spring retainçr 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 rat~.le is reliably prevented. The supporting part 50~of the valve spring retainer 8 is of streamlined construction on the underside 31 in that the ri~ 32 is chamfered o~ or flatten-ed. The rim 32 can also be of arcuate construction, in which case it must retain a form which ensures reliable application agalnst the stop 25.
, . ..
.
~2~3~
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 31eeve 20, fitment taking place ~hrough the guide 34, but only after the first few turns of ~he 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 par~s achieved. Subsequent tightening of the valve spring 7 is then effected ~ia the setscrew 9.
The guide 34 comprises a connection piece 36 which is constructed according to the particular applicatlon involved.
This connecting piece 36 is, in the exa~ple illustrated, , con3tructed for a push-in connection, the 0-ring pro~ided at the bottom end ensuring the neces~ary seal.
Fig. 2 show~ a spring sleeve 20 in partial elevation and in cros~ection, and it is clear where and how the through-flow passages 26 and 27 are located. In between ~re in each case abutments 25 which effectively limit the travel of the valve spring retainer 8.
Fig. 3 shows an embodiment in whlch the throughbore 10 is ~ealed against dust by additions. For this purpose, a pin 37 is provided which is pressed on the 3eat 38 by the 25 spring 39. This pin 37 is pressed out of the seat 38 when, upon the valve piston 6 responding 9 pressur~sed medium passes into the interior of the spring sleeve 20. The fact that pene~ration of dust through the throughbore lOI i9 , ., ~3~
effectively prevented means that the efficacy or accurac.y of response of ~he pressure limiting valve is additionally enhanced.
In ~he case of ~he pressure limiting valve ~hown in Fip. 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 seal of the part of the housing which acco~modates the valve spring 7 is achieved by an interposed intermediate mem~er 40, This intermediate member 40 accommodates an inter-10 mediate piston 41 which is sealed by an 0-ring 42. The pressurised medium must and can only escape here through the lateral outlet ports 43, 46.
The intermediate member 40 has an external screwthread 44 and an internal screwthread 45 which are exactly adap-ted to the corresponding screwthreads of thP spring sleeve 20 or guide 34. Thus~ this intermediate member can be inser-ted as a complete component between the existing or corres-pondingly constructed other parts and a completely effeetive pre3sure limiting valve 1 is avail~ble. As explained, such a pressure limiting valve has an interior which i3 com-- pletely sealed by pressurised medium snd 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 intermedlate piston 41 has a shoulder 47 on which bears the head of the pin 37, the pin head havlng a flattened face 48. ~he intermediate pi~ton ~2~3~
~ 17 41 is con~tituted by a steel pin 49 which is seated in a synthe~ic plastics sleeve 50.
Fig. 5 shows a pressure limitlng valYe 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 ~0 and ~he through-flow bore 10 in ~he setscrew 9 9 are just a~ large or may even be larger than the throughflQw area of the feed line 52. Upon compari~on of Fign 5 with the preoeding f-lgures, it is clear-that the guide 34 is unaltered i~ it~ outside dimensions and has only a corre3pondingly enlarged piston bore 5. To prevent the penetration of dust~ the compara-tively large through bore 10 i~ secured by ~ sealing pin 53~
This sealing pin 53 is biased by a spring which is ini.tially . ~
tensioned by the valve spring retainer 54, This valve spring retainer 54 has reces~e~ 55, 56 in order to 8110w the pressurised medium to emerge rapidly from the pressure Iimiting valve 1. The sealing pin 53 is therefore tightly seated on the seat 57 in the region of the through bore 10 : 20 Also the features which are the object of the preceding Claimq are or can be used for expedient further develop-ment of th~ embodiment shown in Fig. 5.
The adapter 58 makes it possible for the guide 34 which has the conventionaI connection di~ensions and the correspondingly large volume valve body 2 or spring ~leeve 20 to be used. The adapter provides the necessary connec-tion between the two parts.
Fig~ 6 finally shows a pressure limiting valve which :,, ~2~3~
can be used in i~dividual prop val~es or in cont~ol 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 pres~ure li~iting valve, on the other hand, corresponds exactly to that of the ~alve 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 passagss 26, 27 constructed on the inside and ths abutment 25. Also the valve spring retainer 8 has remained unaltered as has also the connection between guide 34 and spring sleeve 20. The 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 de~cribed embodiments.
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Fig. 7 shows a synthetic plastics tube 62 -inserted lntQ
the correspondingly widened piston bore S. This synthetic plastics tube 62 which has the same outside and inside diameter as the synthetic plastic~ bush 50, facilitates fitment of the 0-ring 17 which in this way can be pushed ~ubstantially more easily into the groove 18, the bo~tom edge of which is, of coursel partially dispensed with in the lower zo~e. This edge i9 then augmented or replaced by the top edge 68 of the synthetic pla5tic5 tube 62.
The inside diameter 64 of the synthetic plastics tube 62 corresponds to the outside diameter 63 of the val~e piston 6 so that this latter is reliably and easlly guided in the piston bore S.
.
, 3~
_ 19 -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 Yalve piston 6 is expediently inserted into the synthetic plastics ~ube from below so that the 0-ring can be inserted into the piston bore 5 even doubled at the time of assembly.
Provided at the top end of the widened out piston bore 5 is a web 69 to guarantee an accurate positioning of the 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-ponds in diameter to the inside diameter 64 of the syntheticplastics tube 62 or is larger as Fig~ 8 shows. With a larger piston bore 3 there is at the top end in the region of the bottom ed~e 67 an abutment 70 which, upon assembly, indicates and establishes the optimum seating for the - 25 synthetic plastics tube 62.
Fig. 9 shows the bottom end of a pressure ~imiting Yalve 1, particularly the guide 34. The drawing illustrates that also wi~h valve pistons 6 of small-diameter, here for example ~ ., ~3~
5 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 Q-rings 17 fitted în this case is equal to or may even be less than that of the radial bores 14, 15, 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 0-ring 17 is shown by solid lin23 in the IO 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 en~lsaged that the rear wall 71 be constructed to extend obliquely to the . .
: 15 valve piston 6 in the direction of the valve spring retainer 8.
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Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A fluid pressure limiting valve comprising a valve body having a circular chamber, an inlet means at one end and an out-let means at the other end, a valve piston slideably mounted in a bore in said inlet means and slideable through an O-ring seal, said valve piston having an axial bore communicating with radial bores which are closed in one position and which open into said chamber in its open position, a spring located in said chamber, a retainer 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 ring 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 chamber having a plurality of channels formed in a wall of the valve body, which channels extend paral-lel to the axis of the chamber and 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.
2. A pressure limiting valve according to claim 1, charac-terised in that the valve body consists of a sleeve having at both ends a screw thread and is closed at 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 at the outlet end engaged by the valve spring.
3. A pressure limiting 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. A pressure limiting valve according to claim 1, charac-terised in that a spring loaded pin having a seat seals the out-let against ingress of dust.
5. A pressure limiting valve according to claim 2, charac-terised in that the throughflow areas of the axial and radial bores 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 throughflow area of a feed line connected to said bore in said inlet means.
6. A pressure limiting valve according to claim 1 charac-terised 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 cor-responds to the outside diameter of the valve piston.
7. A pressure limiting valve according to claim 6, charac-terised 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 limiting valve according to claim 2, charac-terised in that the throughflow areas of the axial and radial bores in the valve pistons, the chamber which accommodates the valve spring and the outlet opening in the setscrew are equal to or greater than the throughflow area of a feed line connected to said bore in said inlet means, 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 dia-meter of the valve piston and characterised in that the O-ring let into the groove is of a thickness which is equal to or less than the diameter of the radial bores.
9. A pressure limiting valve according to claim 1, charac-terised in that the O-ring is accommodated in a groove which is longer axially of the piston than it is radially.
10. A pressure limiting valve according to claim 1, charac-terised in that the O-ring is accommodated in a groove which has a rear wall constructed to extend obliquely with its narrow end nearer to the retainer member.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3409677 | 1984-03-16 | ||
| DEP3409677.9 | 1984-03-16 | ||
| DE3446210 | 1984-12-19 | ||
| DEP3446210.4 | 1984-12-19 | ||
| DEP3503898.5 | 1985-02-06 | ||
| DE3503898 | 1985-02-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1243921A true CA1243921A (en) | 1988-11-01 |
Family
ID=27191801
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000476616A Expired CA1243921A (en) | 1984-03-16 | 1985-03-15 | Pressure limiting valve |
Country Status (6)
| Country | Link |
|---|---|
| BE (1) | BE901950A (en) |
| CA (1) | CA1243921A (en) |
| DE (1) | DE3546557C2 (en) |
| ES (1) | ES8606936A1 (en) |
| FR (1) | FR2561347B1 (en) |
| GB (1) | GB2159923B (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3523548A1 (en) * | 1985-07-02 | 1987-01-15 | Gewerk Eisenhuette Westfalia | PRESSURE LIMIT VALVE |
| DE3637888A1 (en) * | 1986-11-06 | 1988-05-19 | Gewerk Eisenhuette Westfalia | PRESSURE LIMIT VALVE, IN PARTICULAR FOR HYDRAULIC EXTENSION SYSTEMS |
| CA2033066A1 (en) * | 1989-05-19 | 1990-11-20 | Richard Voss | Pressure limiting valve with stepped or double piston |
| WO1991003621A1 (en) * | 1989-09-01 | 1991-03-21 | Richard Voss Grubenausbau Gmbh | Pressure limiting valve with teflon seal |
| DE10312175A1 (en) * | 2003-03-19 | 2004-10-14 | Robert Bosch Gmbh | Pressure relief valve |
| DE102004005747A1 (en) | 2004-02-05 | 2005-08-25 | Voß, Christina | Pressure relief valve with hydraulic sealing ring |
| CN100337054C (en) * | 2005-03-04 | 2007-09-12 | 王纪良 | Release valve controlled by pressure to open and close |
| FR3091741B1 (en) * | 2019-01-14 | 2021-04-02 | Air Liquide Medical Systems | Improved medical fluid delivery outlet |
| CN110966418A (en) * | 2019-11-21 | 2020-04-07 | 中国航发西安动力控制科技有限公司 | Spring seat for hydraulic valve parts |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB793724A (en) * | 1954-11-15 | 1958-04-23 | Alexander Osmond Champion | Pressure regulating and check valve |
| US2775483A (en) * | 1955-01-20 | 1956-12-25 | Scovill Manufacturing Co | Aerosol bomb filling and dispensing valve |
| DE1812616A1 (en) * | 1968-12-04 | 1970-06-18 | Salzgitter Maschinen Ag | Hydraulic cylinder made of metal, especially for hydraulic pit rams |
| DE6942209U (en) * | 1969-10-29 | 1970-01-29 | Lorch & Co Kg J | SAFETY VALVE |
| DE1964127A1 (en) * | 1969-12-22 | 1971-06-24 | Langen & Co | Adjusting device |
| DE2815919A1 (en) * | 1978-04-13 | 1979-10-18 | Thyssen Industrie | PRESSURE RELIEF VALVE FOR HYDRAULIC REMOVAL ELEMENTS OF UNDERGROUND PIT OPERATION, PRESENTLY FOR MINING |
| DE2830891C2 (en) * | 1978-07-13 | 1986-01-30 | Heilmeier & Weinlein Fabrik für Oel-Hydraulik GmbH & Co KG, 8000 München | Safety valve |
| GB2043210B (en) * | 1979-02-28 | 1983-02-09 | Skotchinsky Inst Gornogo Dela | Controlled pressure-release valve |
| DE8216072U1 (en) * | 1982-06-03 | 1982-10-07 | Dams, Jörn, 4320 Hattingen | PRESSURE LIMIT VALVE |
| DE3314837A1 (en) * | 1982-06-03 | 1983-12-08 | Jörn 4320 Hattingen Dams | PRESSURE LIMIT VALVE |
| DE3245667C2 (en) * | 1982-12-09 | 1986-09-11 | Hermann Hemscheidt Maschinenfabrik Gmbh & Co, 5600 Wuppertal | Pressure relief valve for HFA fluids |
-
1985
- 1985-03-13 DE DE19853546557 patent/DE3546557C2/en not_active Expired
- 1985-03-14 GB GB08506651A patent/GB2159923B/en not_active Expired
- 1985-03-15 ES ES541313A patent/ES8606936A1/en not_active Expired
- 1985-03-15 FR FR8503889A patent/FR2561347B1/en not_active Expired - Fee Related
- 1985-03-15 CA CA000476616A patent/CA1243921A/en not_active Expired
- 1985-03-15 BE BE0/214657A patent/BE901950A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| ES8606936A1 (en) | 1986-05-16 |
| BE901950A (en) | 1985-07-01 |
| FR2561347A1 (en) | 1985-09-20 |
| GB2159923A (en) | 1985-12-11 |
| GB2159923B (en) | 1987-07-15 |
| FR2561347B1 (en) | 1990-01-19 |
| DE3546557C2 (en) | 1989-06-15 |
| ES541313A0 (en) | 1986-05-16 |
| GB8506651D0 (en) | 1985-04-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |