Note: Descriptions are shown in the official language in which they were submitted.
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1 BACKGROUND OF THE INVENTION
2 1. Field of the Invention
3 This invention relates to an air cut-off valve which finds
4 application as a safety device for controlling the air intake of an engine.
2. Prior Art
6 An air cut-off valve is commonly employed to close the air
7 intake line extending between the turbocharger and air intake manifold
8 of a diesel or gas-fuelled engine. The valve is used to withhold air
9 supply from the engine, in the event that it is sensed that hydrocarbons
are entrained in the air. These valves are particularly needed, for
11 example, in connection with the engines of a drilling rig, where there
12 is a significant possibility that gas will escape from the well and cause
13 the engines to continue running, even though the fuel supply has been
14 closed off. The continued operation of the engines carries a high risk of
causing the escaping gas to ignite.
16 The cut-off valve heretofore most widely used in this service
17 in North America is disclosed in Canadian Patent 587,457, issued to
18 Oakes. This valve is described in some detail below because the present
19 invention uses some of its concepts, but incorporates modifications
with a view to overcoming some of its shortcomings.
21 The Oakes valve comprises a hollow, box-like, sectional
22 housing having a greater length than width. This housing is formed
23 using two hollowed-out halves or sections which are bolted together. An
24 air inlet port extends through the upper end of the transverse upstream
wall of one such section and an outlet port extends through the upper
` 26 end of the downstream wall of the other section. The ports are
27 linearly aligned. In use, the valve is inserted in the air line so
28 that the ports and the chamber internal of the housing form part of
.,
29 the air flow path. The long housing extends well below the air line,
for a purpose to be explained.
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1 A valve member, comprisiny a stem and a gate carried thereby,
2 is arranged to reciprocate longitudinally within the chamber. This valve
3 member is movable between stored and operative positions. In the stored
4 position, the gate is disposed in a storage cavity defined by the lower end
of the chamber, out of the air flow pathi the stem extends out the bottom
6 Of the housing. In the operative position, the gate is disposed across
7 the ports, seals against the housing, and effectively blocks the air flow
8 path.
g A spring is provided to bias the stem and its attached gate
from the stored position to the operative position. This spring is positioned
11 around and along the stem and extends between the bottom wall of the housing
12 and a shoulder on the val~e member. When the valve member is locked by
13 suitable locking means in the stored position, the spring is compressed.
14 When the locking means is released, the spring expands and biases the valve
member to the operative or blocking position.
16 The aforementioned releasable locking means comprises a
17 lock-out cylinder which has a spring-loaded shaft that engages a recess
18 in the valve stem, to lock the stem in the stored position.
19 In summary, the Oakes valve involves in concept the following
features:
21 (1) a gate positioned in a sealed hollow, in-line housing,
22 ~ which gate is movable between a stored position, in
23 which it is locked in a storage cavity formed by the
24 housing out of the air flow path, and an operative
position, in which it blocks and seals the air flow
26 path; and
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l (2) a stem which carries the gate and biases it between
2 the positions, sa;d stem cooperating with mover means
3 and locking means to provide the motion needed at the
4 appropriate time.
The present invention also incorporates the aforementioned
6 features. However, in applicant's view, the Oakes valve, while successful,
8 has some shortcomings. The present invention involves significant
structural and conceptual changes which have alleviated or done away
9 with these problems.
One such problem associated with the Oakes valve is its
11 size. It has a thickness of about 2-l/2" and a downwardly extending length
12 of about 17", measured from the centreline of the air line. Since there
13 is a scarcity of available space within the confines of an engine assembly,
4 this bulkiness leads to problems of installation and accommodation.
The valve is necessarily thick in part because the coil spring
16 is mounted around the stem, which arrangement follows from the use of a
17 longitudinal drive.
18 That the valve is necessarily long follows from the
l9 incorporation of longitudinal movement of the gate and stem between
longitudinally aligned storage and operative positions.
21 Another problem has to do with sealing of the stem. It
22 protrudes out of the housing through an opening formed at the parting
23 line of the housing sections. Tapping in at the parting line is
24 necessary in order to be able to install a seal in a facile and in-
expensive manner. However, it is difficult to so accurately machine the
26 semi-c;rcular openings in the housing sections that they are perfect
27 matches, so that the seal, when mounted in the surfaces of the
28 openings, fits properly and provides an air-tight seal between
29 the stem and the housing.
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1 Still another problem has to do with the positioning of the
2 lock-out cylinder. In the Oakes valve, it is positioned in a plane
3 perpendicular to the parting plane of the housing. This is done
4 because it is easier to tap into the transverse wall of the housing than
to tap in at the parting line. This arrangement further interferes
6 with the objective of developing compactness as an attribute of the valve.
7 With this background in mind, it will be understood that there
8 js a need for an air cut-off valve which is characterized by compactness,
9 ease of sealing, and ease of manufacture.
lo SUMMARY OF THE INVENTION
11 In accordance with the present invention, an air cut-off
12 valve is provided in which the valve member swings through an arc about
13 a transverse pivot member, when moving between the stored and
14 operative positions.
One result of this arrangement is that the pivot member
16 may be journalled in the side walls of the valve and sealed in an ef-
17 fective and simple manner.
18 Another result is that the length of valve is relatively
19 short, as it does not have to accommodate a stem which moves between
longitudinally aligned positions.
21 The arrangement further lends itself to comblnation with a
22 side drive. That is, the biasing means, such as a spring, may be
23 disposed in the main plane of the housing to act against the stem from24 the side. The increase in valve thickness, which arises from concentrically
positioning the stem, spring and gate, is thereby avoided.
26 Still another advantage of the arrangement is that it lends
27 itself to using a hollowed out body and flat cover to form the housing.
28 With such a housing, the lock-out means may be tapped into the side wall
29 of the body. As a result, the lock-out means extends in the main plane of the
housing, thereby ensuring compactness.
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1 By making these modifications, a cut-off valve is provided
2 which has a thickness of about 1-1/2" and a length from the air line
3 of about 10". Also, sealing of the valve is improved.
4 Broadly stated, the invention is an air cut-off valve
comprising: a housing formed by a hollow body and a flat cover secured
6 thereto, said housing defining an internal chamber and having upstream
7 and downstream walls which form inlet and outlet ports respectively,8 said housing having gate and stem ends and being adapted to be connected
g in an air supply line whereby the ports and chamber form part of theair flow path, said ports being positioned at one side of the chamber
11 at the gate end, whereby the other side of the chamber provides a
12 storage cavity; a valve assembly comprising a stem having a gate mounted
13 thereon at one end thereof, said gate being located in the gate end
14 of the chamber, said stem extending into the stem end of the chamber;
a pivot member positioned in the stem end of the chamber; said stem
16 being pivotally mounted on the pivot member so that the gate is adapted
17 to move about said pivot member along an arc from the stored position
18 in the storage cavity to an operative position in which it blocks one
19 of the ports and seals against the wall forming such port; said valve
assembly being wholly disposed within the chamber; lock-out means,
21 associated with the stem end of the housing and being positioned so
22 that its main axis extends substantially parallel to the main plane
23 of the housing, for mechanically locking the stem in the stored position
24 until disengaged, said lock-out means being manually disengageable
to release the stem when required; and mechanical drive means, also
26 associated with the stem end of the housing and being positioned so
27 that its main axis extends substantially parallel to the main plane of
28 the housing, for normally urging the stem to the operative position,29 when the lock-out means is disengaged, to shift the gate from the stored
position to the operative position.
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1 DESCRIPTION:OF`.THE DRAWINGS
_ _
2 Figure 1 is a top;plan v;ew of the body of the housing,
3 Figure 2 is a bottom:plan view of the cover of the housing;
4 Figure 3a is a top view, partly in section, showing the body
with the valve member in the stored position, the drive means retracted,
6 and the lock-out means engaged;
7 Figure 3b is identical to Figure 3a except that the valve
8 member is in the operative position~ the drive means is extended~ and
9 the lock-out means is disengaged,
; ~ -6a -
1 Figure 4 is a side sectional view taken along the lines A--A2 of Figure 3bi
3 Figure ~ is a side sectional view taken along the line B--B
4 of Figure 3a;
Figure 6 is a perspective view of a component, the compensator
6 plate, used in the assembly; and
7 Figure 7 is a top view, partly in section, similar to Figure 3a
8 but showing a cylinder as the drive means and a stop screw to limit the
9 extent of valve member rotation.
DESCRIPTION OF THE PREFERRED EMBODIMENT
11 The Housing
12 The cut-off valve 1 comprises a housing 2, which consists
13 of a hollow body 3 and a flat cover 4 bolted together. The housing 2 is
14 T-shaped in configuration, when viewed in plan.
The body 3 is formed by a transverse wall 5, termed "the
16 upstream wall", and a side wall 6. An internal T-shaped recess or
17 chamber 7 is defined by the walls 5,6.
18 The upstream wall 5 comprises a collar 70, which defines
19 an inlet port 8 extending through said wall and communicating with one
side of the internal chamber 7. The collar 70 is adapted to connect
21 with the air supply line (not shown) of the motor.
22 The inner surface of the upstream wall 5 is stepped slightly,
23 to provide an elevated upper surface 9 and a recessed lower surface 10,
24 said surfaces being divided by a shoulder 11.
A first bore 12 extends through the side wall 6 at its lower
26 end, to accommodate a lock-out means 13.
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A second bore 14 similarly extends through the side wall
2 6 above the first bore 12, to accommodate a drive means 15.
3 A third bore 16 extends through the lower end of the upstream
4 wall 5, to accommodate a pivot shaft 17.
Turning now to the cover 4, it conforms in shape to the out-
6 line of the body 3. Both the body 3 and cover 4 have machined contact
7 surfaces which sealably engage at A and B to prevent air leakage.
8 The cover 4 comprises a transverse wall 18, termed 'the down-
9 stream wall'. The cover 4 further comprises a collar 19, which defines
an outlet port 20. The outlet port 20 is aligned with the inlet port 8
11 and provides communication through the downstream wall 18 with one side
12 of the internal chamber 7. The collar 19 is adapted to connect with the
13 a;r supply line.
14 The inlet port 8, internal chamber 7 and outlet port 19 are
operative, when the valve 1 is installed in an air supply line, to form
16 part of the air flow path.
17 A fourth bore 21 extends through the lower end of the
18 downstream wall 18 and is aligned with the third bore 16i this fourth
19 bore 21 functions to accommodate the pivot shaft 17.
The Blocking and Sealing Means
21 A gate valve 22 is pivotally mounted for movement within
22 the chamber 7. The gate valve 22 functions to block and seal one of the
23 ports 8, 20, to interrupt the air flow.
24 The gate valve 22 comprises a biasing element or stem 23
and a sealing element or gate 24 connected with the upper end of
26 said stem. The stem 23 and gate 24 are wholly contained within the
27 chamber 7.
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1 The vertical stem 23 ;s p;votally mounted at ;ts lower end2 on a horizontal pivot shaft 17. The pivot shaft 17 is journalled in
3 the third and fourth bores 16, 21. 0-rings 25 seal the pivot shaft 17
4 against the bounding surfaces of the bores 16, 21, to prevent air
leakage.
6 The stem 23 may be pivoted to carry the gate 24 along an arc
7 between a stored position, shown in Figure 3a, in the storage c~vity
8 portion 26 of the chamber 7, and an operative position, shown in Figure9 3b, wherein it functions to block one or both of the ports 8,20.
The circular gate 24 is formed with a central bore in which
11 the upper end of the stem 23 is received. The gate 24 is free-floating
12 on the stem 23 - that is, it has a loose tolerance fit on the stem so
13 that it can rotate about the stem's main axis and can tilt at a slight
14 angle relative to said axis. In addition, the gate 24 is formed of
resilient elastomer material. As a result of providing the free-floating
16 capability and forming the gate of resilient material, a particularly
17 effective seal may be achieved.
18 A preferred means for mounting the stem 23 on the pivot
19 shaft 17 is provided. More particularly, the stem 23 has a clevis 27
at its lower end. An L-shaped compensator plate 28 extends through
21 the clevis 27. The compensator plate 28 and clevis 27 define aligned
22 bores 29, 30, through which the pivot shaft 17 extends. A key 31 extends
23 through suitable bores (not shown) in the shaft 17, plate 28, and clevis
24 27, to hold them together. The plate 28 is formed with a resilient
shoulder member 32, to bear against the clevis 27 when it moves to
26 the operative position.
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1 Locking Means
2 A lock-out cylinder 13, of conventional design, is positioned
3 in the first bore 12 of the housing 2, to engage the compensator plate 28
4 and restrain the stem 23 keyed thereto in the stored position. More particu-
larly, the cylinder 13 comprises a piston 33, which is normally outwardly
6 urged by a spring ~not shown) mounted within the cylinder barrel 34.
7 The piston 33 engages a notch 35 formed in the compensator
8 plate 28 to lock the latter against rotation. The end 36 of the piston
9 33, remote from the compensator plate 28, extends out the end of the
barrel 34. This piston end 36 may be manually pulled with pliers to
1l disengage the piston 33 from the notch 35 and thereby release the
12 stem 23.
3 Drive Means
14 A plunger 37 is positioned within the second bore 14 of
the housing 2. The outer end 38 of this plunger 37 contacts the stem 23.
16 A spring 39 is positioned within the bore 14 and acts to normally urge the
17 plunger 37 outwardly against the stem 23. A plug 40 is screwed into the
18 outer end of the bore 14, to provide a footing for the spring 39.
19 Upon disengaging the lock-out piston 33 and releasing the
plate 28, the spring 39 extends and drives the stem 23, to cause it to
21 rotate about the pivot shaft 17 between the stored and operative
22 position.
23 Operation
24 When installed, the cut-off valve 1 is positioned in the air
supply line with its upstream and downstream walls 5, 18 transverse to the
26 axis of the line. The ports 8, 20 communicate with the air line. The
27 ports 8,20 and chamber 7 form part of the air flow path.
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1 The valve components are normally in the locked, stored
2 position. That is, the gate valve 22 is in the stored position shown in
3 Figure 3a. The lock-out piston 33 is extended and its end 36 engages the
4 notch 35 of the compensator plate 28. The plunger 37 is pressing against
the stem 23, but it has compressed the drive spring 39. The gate 24 is
6 in the storage cavity portion 26 of the chamber 7 and the flow path through7 the valve 1 is open.
8 When the piston end 36 of the lock-out cylinder 13 is
9 pulled to the right, the piston 33 is retracted from the plate notch 35 andthe stem 23 is then free to rotate. The drive spring 39 expands and the
11 plunger 37 biases or rotates the stem 23 to the left about its pivot
12 shaft 17. The gate 24 is thereby moved along an arc between the stored
13 position and the operative position shown in Figure 3b. The engine vacuum
14 sucks the gate 24 firmly against the downstream wall 18 to block and seal
the outlet port 20.
16 To reset the gate valve 22, the handle 41, secured to the
17 pivot shaft 17, is pulled to rotate the gate valve back to the locked,
18 stored position.
19 Alternative
In a variation of the invention, shown in Figure 7, the
21 locking and driving functions may be combined in a single component,
22 for example an air cylinder 42 pivotally secured to the stem 23.
23 Advantages
24 The specific embodiment of the invention shown in the drawings is characterized by the following advantages:
26 (1) the valve is compact, and
27 ~2) the pivot shaft is easily sealed.
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1 Scope
2 The best mode of the inventi:on has been shown and described
3 in the disclosure. However, this is a speci.fic embodiment of the
4 invention. The scope of the invention is defined in the following
claims.
