Note: Descriptions are shown in the official language in which they were submitted.
CA 02504759 2005-04-20
FLAPPER VALVES WITH SPRING TABS
FIELD OF THE INVENTION
This invention relates to valves, and in particular, to flapper valves.
BACKGROUND OP THE INVENTION
Automotive fluids, such as engine oil or transmission fluids, absorb heat in
use.
To prevent fluid deterioration, this heat often needs to be removed. Heat
exchangers are commonly used for this purpose. Moreover, heat exchangers
are known to perform this function adequately in moderate ambient conditions.
However, in cold ambient conditions, engine oils and transmission fluids can
be
highly viscous. In such conditions, automotive fluids do not flow easily
through
heat exchangers. Starvation of some downstream components, like
transmissions, may even occur. Further, fluid cooling by the heat exchanger
when the fluid is already cold is undesirable, as it results in longer warm up
time for the engine.
In order to avoid these adverse effects, it is known to provide a mechanism
for
bypassing the heat exchanger. One way that this has been done in the past is
to provide a bypass conduit. The bypass conduit is connected in parallel with
the heat exchanger and has a relatively low resistance to the flow of high
viscosity fluids as compared to the heat exchanger. Structures of this type
are
known to avoid starvation of downstream components, but can suffer in that, in
normal or warm operating conditions, the flow is split between the heat
exchanger and the bypass circuit. This requires that the heat exchangers be
made proportionately larger and heavier to achieve the same overall
performance for the cooling system. This added size, and weight and the
3o added costs associated therewith, are undesirable to automotive
manufacturers.
To ameliorate the split-flow problem, it is known in the prior art to provide
bypass valves. Usually, these bypass valves are pressure-activated and are
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integrally constructed with or attached to the heat exchanger. A heat
exchanger exemplary of the foregoing is shown in United States Patent No.
5,499,675 (Haasch et al.), issued March 19, 1996. This structure includes a
flapper valve of spring steel biased in a closed position, to arrest bypass
flow,
and which is adapted to be urged open when the flow resistance through the
normal passages of the heat exchanger is too high, as in cold-start
conditions.
A similar structure is described in United States Patent No. 4,360,055
(Frost),
issued November 23, 1982. Heat exchanger's of this general type can avoid
starvation of downstream lubricated components, and can be adapted such that
1o bypass flow is substantially nil in normal operating conditions, thereby to
permit compact heat exchanger construction. However, in Frost, connection of
the flapper valve to the heat exchanger typically takes place while the heat
exchanger is being mounted to the engine block, using an extension of the oil
return pipe. This adds a step in assembly. Rather than simply mounting the
oil cooler in place using the oil return pipe extension, the flapper valve
must
also be interposed. Further complicating assembly is the fact that the flapper
valve, being constructed out of fairly lightweight material, is prone to
suffering
damage until installation, and thus, requires care in handling. Both factors
add
to assembly costs. In Haasch et al, the flapper valve is also rather delicate
and
2o exposed while the heat exchanger is being mounted to the engine block,
using
an extension of the oil return pipe. The flapper valve is prone to suffering
damage or being dislodged during installation. Also, heat exchangers of the
Frost and Haasch et al type cannot be modified easily to accommodate different
mounting or performance requirements in modern automotive applications.
It is also known to provide heat exchangers including a domed filter plate and
a
snap-in valve clip. One such structure is described in United States Patent
No.
5,544,699 (Robers et al.), issued August 13, 1996. While this structure avoids
the loose part problem associated with Frost, special tools are required to
install the valve clips, and it is relatively inflexible in use in that a
domed filter
plate must be utilized, so that it is limited to oil filters of relatively
>:Ixed
dimensions.
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SUMMARY OP THE INVENTION
In the present invention, a flapper valve assembly includes a flapper valve
with
transverse spring tabs that snap into slots in a valve plate that can be
readily
attached to a heat exchanger or other fluid device having a flow chamber from
which intermittent flow is desired in response to a pressure differential
across
the flapper valve.
According to one aspect of the invention, there is provided a flapper valve
1o assembly for use with a fluid device having a flow chamber with respect to
which intermittent flow is desired. The flapper valve assembly comprises a
valve plate having a fluid port area which defines a valve orifice
therethrough
for communication with the flow chamber. The fluid port area has opposed first
and second sides, one of the sides includes a retaining area spaced from the
valve orifice and adapted to be spaced from the fluid device. The fluid port
area has at least one slot extending therethrough in the retaining area. A
flexible flapper has a fixed end portion including at least one transverse tab
adapted to pass through the slot, so that the flapper engages the fluid port
area. The tab has resilient tangs that extend laterally therefrom and are
2o disposed to engage the retaining area to prevent rotation of the flapper.
The
flapper further has a free end portion movable from a first position where the
free end portion at least partially blocks flow through the valve orifice, to
a
second position where the free end portion unblocks the valve orifice. Bias
means associated with the flapper is provided for urging the free end portion
into the first position.
According to another aspect of the invention there is provided a heat
exchanger
comprising a heat exchange element including an inlet manifold, an outlet
manifold, and flow passages therebetween for the passage of one heat
exchange fluid through the heat exchange element. A valve plate is secured to
the heat exchange element and has a fluid port area defining a valve orifice
therethrough for communication with one of the inlet manifold and outlet
manifold. The fluid port area has opposed first and second sides, one of the
sides includes a retaining area spaced from the valve orifice and adapted to
be
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spaced from structural components of the fluid device. The fluid port area has
at least one slot extending therethrough in the retaining area. A flexible
flapper has a fixed end portion including at least one transverse tab adapted
to
pass through the slot, so that the flapper engages the fluid port area. The
tab
has resilient tangs that extend laterally therefrom and are disposed to engage
the retaining area and prevent rotation of the flapper. The flapper further
has
a free end portion movable from a first position where the free end portion at
least partially blocks flow through the valve orifice, to a second position
where
the free end portion unblocks the valve orifice. Bias means associated with
the
1o flapper is provided for urging the free end portion into the first
position.
Advantages, features and characteristics of the present invention, as well as
methods of operation and functions of the related elements of the structure,
and the combination of parts and economies of manufacture, will become
apparent upon consideration of the following detailed description of the
preferred embodiments of the invention, with reference to the accompanying
drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of an assembly including a heat exchanger and a
spin-on oil filter, the heat exchanger including a preferred embodiment of a
flapper valve assembly according to the present invention;
Figure 2 is an exploded view of the structure of Figure 1 about to be mounted
on an engine block;
Figure 3 is an exploded view of the structure in encircled area 3 in Figure 2;
Figure 4 is an enlarged view of the structure in encircled area 4 in Figure 3;
Figure 5 is a top plan view of the structure in encircled area 3 in Figure 2;
Figure 6 is a partial cross-sectional view taken along lines 6-6 of Figure 5,
with
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the free end portion of the flapper shown in the closed position;
Figure 7 is a view similar to Figure 6, with the free end portion of the
flapper
shown in the open position;
Figure 8 is a partial cross-sectional view taken along lines 8-8 of Figure 5;
Figure 9 is a view similar to Figure 8, showing the flapper apart from the
valve
plate with the tangs shown at their unsprung positions;
Figure 10 is a view similar to Figure 9, showing the tabs of the flapper
engaging
the slots of the valve plate;
Figure 11 is a view similar to Figure 10, showing the tabs relatively further
disposed into the slots;
Figure 12 is a view similar to Figure 11, showing the tabs relatively further
disposed into the slots, with their respective tangs disposed at their sprung
positions;
Figure 13 is a view similar to Figure 8;
Figure 14 is a view, similar to Figure 3, showing a further preferred
embodiment of the invention;
Figure 15 is an enlarged perspective view of the structure in encircled area
15
in Figure 14; and
Figure 16 is a perspective view similar to Figure 14, but showing yet another
3o preferred embodiment of a flapper according to the invention.
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 shows a heat exchanger 22 having a spin-on oil filter 24 or similar
fluid device mounted thereon. Heat exchanger 22 includes a flapper valve
assembly 20 according to a preferred embodiment of the present invention,
and a heat exchange element 28. Heat exchanger 22 is preferably of the type
sometimes referred to as a donut-type oil cooler, but it could be any other
type
of heat exchanger.
1o The donut cooler or heat exchanger 22 is for use with a coolant circuit and
a
lubrication or other fluid circuit and, by way of example, as indicated in
Figure
2, is mounted on a threaded pipe 26 attached to an engine block 27. Threaded
pipe 26 extends through an opening 29 in heat exchanger 22 to permit the
subsequent threaded mounting of oil filter 24 onto pipe 26, as indicated in
Figure 1. This also holds heat exchanger 22 in place.
As best seen in Figure 3, heat exchange element 28 has an end plate 31. Heat
exchanger 22 also includes a face plate 30, and a flapper valve assembly 20
located between face plate 30 and end plate 31. Heat exchange element 28 is
of the stacked plate-type and has a coolant inlet 32 and a coolant outlet 34.
Heat exchange element 28 is formed of a plurality of aluminum plates brazed
together. Each plate has spaced-apart, arcuate openings therein, which are
aligned to form respective flow passages or chambers or manifolds 36, 38.
One of these manifolds can be an inlet manifold, for example, manifold 36.
The other of them can be an outlet manifold 38, but this flow direction could
be
reversed.
Where manifold 36 is the inlet manifold, oil is received into the manifold 36
from an aperture 37 formed in engine block 27 (see Figure 2). This oil passes
3o through heat exchange element 28 to outlet manifold 38, and then passes
upwardly into oil filter 24, and finally down through pipe 26 to be returned
to
engine block 27. However, where this flow is reversed, it comes up through
pipe 26 to filter 24, and then passes through manifold 38 to manifold 36 and
then back through aperture 37 to be returned to the engine.
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It should be understood that the heat exchange element 28 is of generally
conventional construction, and therefore, only those parts necessary for an
understanding of the present invention are shown in the figures and described
herein. For the purposes of the present specification, the exact form of the
heat exchanger element 28 and the spin-on oil filter 24 is not considered to
be
part of the present invention.
Upon a flow of heated oil being forced into the inlet manifold 36 and a flow
of
coolant being delivered to the coolant inlet 32, a flow of cooled oil is
produced
1o at the outlet manifold 38 and a flow of heated coolant is produced at the
coolant outlet 34.
The face plate 30 has a sealing surface 40 and a pair of openings 42, 44. The
sealing surface 40 is adapted to be engaged by the filter 24 and as such, may
be referred to as the filter side of face plate 30. The pair of openings 42,
44
communicate with an annular channel (not shown) in the base of the oil filter
24. One of this pair of openings, namely opening 42, is in fluid communication
with the flow manifold 38 for receiving the flow of cooled oil. The other
opening 44 permits by-pass flow to the oil filter 24, as described further
below.
Turning now to the flapper valve assembly 20, same will be seen to comprise a
valve plate 46 and a flexible flapper 48. The valve plate 46, which is
constructed of stamped aluminum is disposed between and secured, by
brazing, to each of end plate 31 and face plate 30. Valve plate 46 has an
aperture 50 communicating with manifold 38 and face plate opening 42. Valve
plate 46 also has a fluid port area 52 which defines an opening or fluid port
or
valve orifice 56 extending between the manifold 36 and face plate opening 44.
Fluid port area 52 has a first or top side 51, and an opposed second or bottom
side 53 (see Figure 6). One of these sides 51, 53 includes a retaining area 54
spaced from valve orifice 56. Fluid port area 52 includes a pair of spaced-
apart
slots 58 extending therethrough in the retaining area 54. For clarity, fluid
port
area 52 should be understood to be the portion of the valve plate 46
immediately surrounding valve orifice 56 and retaining area 54. Fluid port
area
52 is about the same size or smaller in area than the cross-sectional area of
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manifold 36.
The flapper 48 is disposed within the face plate opening 44 when face plate 30
is attached to valve plate 46, such that the opening 44 circumscribes the
flapper 48. The flapper 48 is preferably stamped from a strip of spring
material,
namely, spring steel, and has, as best illustrated in Figure 4, a fixed end
portion 60 including a pair of transverse, spaced-apart tabs 62 adapted to be
located in slots 58. Flapper 48 also has a free end portion 64 and a resilient
intermediate portion 66 located between the fixed end portion 60 and the free
end portion 64, as will be described further below.
Each tab 62 is substantially planar and is associated with a respective slot
58
and has, as best seen in Figure 4, a substantially planar tang 70. The tabs 62
extend substantially transversely or perpendicularly from the fixed end
portion
60 as shown in Figure 8, and are rigidly connected to the fixed end portion
60,
and more specifically, are part of or formed integrally therewith, along with
tangs 70.
The tangs 70 are disposed at an unsprung position whereat they extend
laterally or in an angled relation to engage the fluid port area 52 of valve
plate
46. Actually, tangs 70 engage the retaining area 54 (see Figures 6 and 7) of
fluid port area 52. Retaining area 54 is on the second or bottom side 53 of
fluid port area 52, but it could be on the first or top side 51, if it is
desired to
locate flapper 48 on the underside of valve plate 46, so that it opens
downwardly or inwardly into flow manifold 36. This downward or inward
orientation would be used when the oil flow direction is reversed, so that it
goes through filter 24 before going through heat exchange element 28, as
mentioned above. In either case, retaining area 54 is adapted to be spaced
from structural components of fluid device or heat exchange element 28 to
provide clearance for tabs 62. Tangs 70 adapt the tabs 62 to resist extraction
from slots 58, and thus, securely mount the fixed end portion 60 of flapper 48
to the plate 46.
In addition to the unsprung position shown in Figure 4 and 8, tangs 70 have a
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sprung position, shown in Figure 12, whereat they extend, in coplanar relation
to the tabs 62. This adapts the tabs 62 for insertion and removal from the
slots 58, as indicated in Figure 12, wherein arrow 72 shows the direction of
insertion. In the preferred embodiment, the tangs 70 are resiliently movable
from the unsprung position to the sprung position in a manner which permits
the tabs 62 to be conveniently inserted into their associated slots 58 merely
by
engaging the projecting ends of the tabs 62 into the slots 58, as shown in
Figure 10, and applying finger pressure to the fixed end portion 60 of the
flapper 48, whereupon the slots 58 urge the tangs 70 to the sprung positions,
as shown by the sequence of Figures 9,10,11,12. Once the valve plate 46 has
been cleared, tangs 70 spring back to their respective unsprung positions, and
the tabs snap into place, as indicated by the sequence of Figures 12,13, to
lock
the flapper 48 in place.
In the preferred embodiment shown in Figures 1-13, the tabs 62 are arranged
parallel to one another. Tangs 70 extend outwardly or away from one another,
but they could also extend inwardly toward one another. In a further preferred
embodiment shown in Figures 14 and 15, the tabs 62 are disposed in angled,
and more specifically, perpendicular or normal relation to one another. Other
2o arrangements of the tabs are possible, as long as horizontal and vertical
rotation of flapper fixed end portion 60 is avoided. In fact, a single tab 62
could be used, as indicated in Figure 16, with tangs 70 extending laterally
therefrom on either side of the tab. In this case, there would only be one
slot
58 in valve plate 46. Further, there could be one or more tangs 70 extending
from each side of the tab.
The free end portion 64 of the flapper 48 is movable, by flexure of the
intermediate portion 66, between a first or closed position, abutting the
fluid
port area 52 in overlying relation to the valve orifice 56 as shown in Figure
6,
and a second or open position, apart from the fluid port area 52 as shown in
Figure 7. Notches 61 (see Figure 4) formed in flapper 48 facilitate this
flexure.
At the open position, the spacing between the free end portion 64 and the
fluid
port area 52 provides for communication between the face plate opening or
outlet 44 and the inlet manifold or flow chamber 36. The dimensions of the
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free end portion 64 are such that flow through valve orifice 56 is restricted,
and
more specifically, substantially arrested, when it is disposed at its closed
position. However, free end portion 64 could be dimensioned only to partially
cover valve orifice 56 to give some permanent by-pass flow, if desired.
The intermediate portion 66 of flapper 48 includes a corrugation or crest 74
formed in the strip of spring material. Corrugation 74 has a pair of walls
76,76
resiliently coupled to one another to resist separation from one another. This
structure provides a spring-tension such that, at its closed position, the
free
to end portion 64 of the flapper 48 is urged against the fluid port area 52.
As mentioned above, in use, the heat exchanger 22 is mounted on an engine
between the engine block 27 and a conventional oil filter 24. In normal
operating conditions, wherein relatively warm, substantially free-flowing oil
is
delivered to the inlet manifold 36, bias provided by the intermediate portion
66
maintains the free end portion 64 of the flapper 48 in a closed position
against
the fluid port area 52 to restrict, and more specifically, substantially
arrest
bypass flow through the valve orifice 56. Thus, most of the flow arriving at
the
inlet manifold 36 passes in heat exchanging relation through the heat exchange
element 28 to the outlet manifold 38, transferring heat in the process, prior
to
passing through outlet 42 in the face plate 30 to the oil filter 24, for
filtering,
and subsequent return to the oil circuit through oil return pipe 26.
In contrast, in conditions such as are present in the context of an engine
start
in relatively cold ambient conditions, wherein the oil is relatively cold,
viscous
oil is delivered to the inlet manifold 36. In these circumstances, the flow
resistance through the heat exchange element 28 is relatively high, with the
result that the viscous oil forces the free end portion 64 of the flapper 48
into
an open position spaced from the fluid port area 52, as indicated by the
sequence of Figures 6 and 7 such that flow passes from the inlet manifold 36
through opening or outlet 44 directly to the filter 24. Periodic, momentary
high
pressure bursts or spikes also bypass the heat exchange element 28 in this
manner, if the heat exchanger 22 encounters transient high pressure spikes in
the oil circuit.
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The mechanical properties of flapper valve assembly 20 are selected to suit
the
operating parameters of the heat exchange element and lubrication circuit with
which it is used; and in particular, flapper 48 has a spring constant such
that it
will open under predetermined pressure conditions.
The foregoing structure is of particular advantage, in that it obtains
relatively
high cooling performance in normal operating conditions, when cooling is
needed, as substantially all oil passes through the heat exchange element to
transfer its heat to the engine coolant in such conditions. At the same time,
the structure avoids starvation of mechanical components in high pressure
conditions, such as cold weather startup, and also avoids metal fatigue that
can
result from pressure spikes in the thin-wall plates forming the heat
exchanger,
since in such conditions bypass flow occurs.
Having described preferred embodiments of the present invention, it will be
appreciated that various modifications may be made to the structures
described above without departing from the spirit or scope of the invention.
Foremost, whereas the flapper valve assembly of the preferred embodiment is
shown in use with a heat exchanger, it should be understood that the invention
is not so limited, and may be deployed in association with any fluid device
having a flow chamber from which intermittent flow is desired.
Tt should also be understood that whereas the disclosure illustrates and
describes a heat exchanger of specific construction, modifications therein are
also contemplated to fall within the scope of the invention.
Heat exchangers, for example, that are not of the donut type may be utilized.
As well, the heat exchangers need not be formed of stacked plates, nor is it
required that all or any of the various components be brazed to one another.
The plates forming the heat exchanger could, for example, be brazed to one
another, and the valve plate secured thereto by an adhesive, such as epoxy.
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It will also be appreciated that flapper valve assembly 20 can be located at
any
position relative to the fluid device, and that orientation of flapper 48
could be
reversed, so that it is located on the underside of valve plate 46 rather than
on
the top side as illustrated.
As a further modification, whereas the flapper of the preferred embodiment
consists of a strip of simple spring steel, a resilient bimetallic strip could
be
readily substituted therefor, to tune the amount of bias provided according to
different temperatures. For example, a bimetallic flapper could open in cold
conditions to give bypass flow even if the pressure was not excessive, and
close in warm conditions to give pressure relief as needed. Of course, a
bimetallic flapper would still have a flexible intermediate portion and
provide
pressure spike protection even in warm flow conditions.
As well, whereas the flapper intermediate portion of the preferred embodiment
is provided with a corrugation to augment the spring-tension urging the second
portion of the flapper against the fluid port area at the closed position,
this
need not be the case. The corrugation could, for example, merely bias the free
end portion of the flapper for movement to its closed position. As well, the
corrugation could be omitted and the flapper could be constructed out of a
material which would be sufficiently resilient to close the valve orifice
without
the presence of a corrugation.
It should also be noted that whereas in the preferred embodiments illustrated,
the flapper intermediate portion, that is, the portion of the flapper that
extends
between the fixed end portion and the free end portion is elongate, this need
not be the case. For example, the intermediate portion could take the form of
a resilient living hinge connecting the first portion and the second portion.
Further, whereas the free end portion of the flapper illustrated in each of
the
preferred embodiments is substantially planar, it will be evident that any
form
of protuberance could be formed on the free end portion to fit, in whole or in
part, in any form of fluid port or valve orifice.
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As well, the construction of the flapper free end portion need not be limited
to
the spring material of which the remainder of the flapper is constructed.
Also,
coatings could, for example, be applied to assist in sealing.
As well, whereas the free end portion has been herein described as being
movable between the open position and the closed position by flexure of the
intermediate portion, this flexure may only be one component of the
movement, and the free end portion itself may undergo flexure.
1o From the foregoing, it will be evident to persons of ordinary skill in the
art that
the scope of the present invention is limited only by the accompanying claims,
purposively construed.
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