Note: Descriptions are shown in the official language in which they were submitted.
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1 The present invention relates to fluid pressure relief valves.
2 Relief valves are conventionally used in fluid pressure sys-
~ tems for the purpose of protecti~g the fluid pressure generating
4 equipment, such as a cylinder, cylinder heads, bol~s~pump valves9
packing or cups, so that, in the event of malfunction or closing
6 an external valve in error or excessive pressure as caused by a
7 clogged drilling bit~ the relief valve is biased to an open fluid
8 discharge position enabling the operators to correct the malfunc-
9 tion without damage to the equipmen~.
Fluid pressure relief valves presently in use and as disclos-
11 ed by prior patents generally relate to valve structure which in-
12 cludes a valve stem or mandrel moved longitudinally in response ~o
13 predetermined fluid pressure which shears a pin or ruptures a
14 frangible disk, or the like. The pressure setting in which these
valves open to release such pressure is predetermined by the pres-
16 sure necessary to shear the shear pin or rupture the frangible
17 disk. The pressure at which such a valve opens is thus predeter-
18 mined by the known rating or shearing force required to shear a
19 pin or rup~ure a frangible disk of predetermined thickness.
~hear type valves are dangerous in that they can be rendered
21 i~opera~ive by a workman, tired of rese~ting the valve~ putting
22 more than one shear pin or nail through the shear bar on one type
23 safety relief valve or using extra strong metal, such as an Allen
24 wrench through the shear stem in another type shear relief valve.
Rupture disks have the disadvantage of being difficult to service
26 in the field and each disk has only one rupture valueO
27 ~is invention overcomes this disadvantage by providing a
28 pressure relief valve for protection of fLuid pumps or lines in
29 which selected ones of a plurality of rupture bands~ extending
transversely across an ou~wardly projecting end of an excess pres-
31 sure moved valve stem, may be cut in the field to provide a relief
32 valve having a lower pressure value.
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1 In the drawings which illustrate embodiments of the invention.
2 Figure 1 is a side elevational view of ~he valve with a por-
3 tion of the safety cap in section for clarity;
4 Figure 2 is a vertical cross sectional view, to a larger
scale3 with the safety cap removed;
6 Figure 3 is a fragmentary elevational view of the top part of
7 the valve, wi~h the safety cap removed, when rotated at gao a~out
8 its longitudinal axis from the position of Fig. 2;
9 Figure 4 is a horizontal sect~onal view taken substantially
along the line 4---4 of Fig. 2;
11 Figure 5 is a side eleva~ional view of the rupture band ele-
12 ment, per se; and,
13 Figure 6 is a vertical cross sectional view ~aken substan-
14 tially along the line 6---6 of Fig. 5.
In the drawings the reference numeral 10 indicates the valve
16 which is generally cylindrical. The valve 10 comprises a hollow
17 body 12 having an internally thr-eaded lateral exhaust port 14
18 intermediateli~s ends. The body 12 is provided, at one end, with
19 inlet means 16 adapted to be connected with a line 17 containing
fluid under pressure. The other end of the body supports rupture
21 band means 18 adapted to be ruptured by excess fluid pressure in
22 its inlet end 16 for releasing such fluid pressure through the
23 lateral port 14~ The term 'trupture" as used herein indicates a
24 longitudinal stretching exceeding the tensile strength of ~he band
means as opposed to a shearing action of frangible material. The
26 valve body 12 is longitudinally centrally bored and counterbored,
27 as at 20-and 229 defining an annular shoulder 24 in its end por-
28 tion opposite its inlet for the purposes presently explained.
29 The inlet means 16 comprises a sleeve 26 having external
threads 28 and 30 at its respective ends, threadedly received by
31 the body counterbore 22 and the pressure line 17, respectively.
32 The sleeve bore 31 forms a fluid inlet passage. Obviously, the
33 sleeve ~6 may be internally threaded for receiving the pressure
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1 line 17, if desired. The inwarclly disposed end of the sleeve 26
2 is counterbored and threaded~ as at 32 3 for receiving a bushing 34.
3 The bore 36 of the bushing 34 forms a sealing face for the
4 purposes presently explained. The bore 36 tapers ou~wardly, as at
38, to fonn a tapered surface facing the rupture band means 18.
6 0-rings, or the like, 40 and 42 seal the sleeve threads 28 and 32
7 with the valve body and bushing, respectively.
8 A cylindrical plug 44 is coaxially received by the valve body
9 bore 20 and projects beyond the end of the valve body opposite the
inlet means 15. The inward end of the plug 44 is provided with an
11 o~tstanding annular flange 46 closely received by ~he body counter-
12 bore 22 and defines an annular shoulder 48 abutting the valve body
13 shoulder 24 to prevent axial movement of the plug 44 out of the
14 body. A snap ring 50, disposed in a suitable groove formed in the
periphery of the plug 44, abuts the end of the valve body opposite
16 its inlet end to preven~ axial movement of the plug 44 into the
17 valve body. The plug 44 is coaxially bored~ as at 52, for slid-
18 ably receiving the stem 54 of valve means 56.
19 The valve means 56 comprises a piston-like valve 58 formed
on the end portion of the stem 54 opposite the rup~ure band means
21 18 and closely received slidably by the sealing face 36 and is
22 normally disposed intermediate the ends of the bushing 34. Pack-
23 ing 60 surrounds the valve stem 54 adjacent the surface of the
24 valve 50 facing the inlet end of the sleeve 26 and is held in
a~5 place by a washer 62 and clip 64 secured to the valve stem. Fluid
26 pressure in the sleeve bore 31 seals the packing 60 with the seal-
27 ing face 36.
28 The other end of the valve stem 54 is connected with a gen-
29 erally rectangular valve stem lug 66 which pro3ects beyond the
outwardly d~sposed end of the plug 44 a selected distance through
31 a diametric slot 68 intersecting the bore 52. The inner limit of
32 the slot 68 is defined by a flat surface 69. Inwardly of the
33 axial outer end surface of the plug the slot 68 is laterally
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1 widened to form opposing parallel diametrically opposite rectangu-
2 lar recesses 70 intersecting the plug sur~ace 69 and spaced out-
3 wardly of the cylindrical plane of ~he plug bore 52 for receiving
4 a rupture band element 72.
The rupture band element 72 is formed from a section of sheet
6 metal and is substan~ially inverted U-shape in end elevation (Fig~
7 6) having leg members 74 joined by a bight portion 75. Each of
8 the leg members 74 are doubled back upon themselves to form closed
9 loops 74', cooperatively received by the rectangular slots 70.
The loops 74' are filled by a pair of 1ug9 76 for the purposes
11 presently explained.
12 The major portion of the legs 74 and bight portion 75 of the
13 element 72 are longL~dinally slotted, as at 78, to define a
14 plurality of equal width equally spaced-apart bands 80 extending
transversely across the outwardly protruding portion of the valve
16 stem lug 66, for the purposes presently explained.
17 The inwardly disposed end o~ the plug 44 is counterbored, as
18 at 82, diametrically equal with the bushing bore 36 and similarly
19 provided with a tapered surface 84 ~acing the bushing 34 to form
a socket for receiving the valve 58 when the bands 80 rupture.
21 Other O-rings seals 86 and 88 seal the valve stem 54 with the
22 bore 52 and the plug 44 with the valve body bore 20. Obviously,
23 the plug 44 may be formed integral with the body 12.
24 The outwardly disposed end of the plug 44 is externally
threaded for receiving a bull plug-like sa~ety cap g0 which is
26 secured to the valve body by swivel thong means 92 to prevent
27 the misplacing of safety cap 90 and for safety from the rapidly
28 moving head 66 once bands 80 rupture.
29 In operation, the rupture means 72 is formed from sheet
material having a known yield value and thus the combined total
31 yield value of the several bands 80, eight in the example shown,
32 equal the max;mum pressure setting of the valve 10. The rupture
33 means 72 maintains the valve means in closed position with pres-
1 sure against the valve 58 from the pressure line 17. As shown in
2 Fig, 2, the corner edges of the stem lug 66 underlying the rupture
3 bands 80 is rounded to prevent a shearing action on the bands. The
4 lugs 76 prevent a col'lapsing action of the loops 74' by pressure
against the bands 80. In the even~ the pressure exceeds the pre-
6 determined value, the rupture bands 80 rupture by the pressure
7 against the valve 58 which moves the valve toward the plug 44 thus
8 opening the valve to exhaust the fluid through the exhaust port 14.
9 The valve can be reset~ after shutting of~ pressure in the line 17,
without removaL from the line 17 by removing khe safety cap 90 and
11 manually moving the valve stem axially and valve 58 into the bush-
12 ing 34 until the stem lug 66 contacts the plug surface 69. After
13 manually sliding the ruptured band means 72 out o~ the slots 68
14 and 70, a new rupture band means is inserted into the slots 70
15 and over the valve stem lug 6~.
16 An important feature of the valve is that when a lower maxi-
17 mum pressure is desired, b,e~ore the valve releases such pressure,
18 a selected one or more of the rupture bands 80 may be cut prior
19 to or after installation so that the remaining uncut bands 80 equal
~he desired maximum pressure.
