Note: Descriptions are shown in the official language in which they were submitted.
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ADAPTER ~SSEMBLY FOR A FILTER AR~ANGEMENT
The present invention relates to the measurement of pressure
differentials across filters in fluid systems. More particularly,
it relates to the measurement of the pressure differential across
the filter element of a spin-on type filter mounted on a filter
pad, such as frequently is utilized in fuel supply, hydraulic, and
lubrication systems of an engine or transmission.
Engine oil lubrication systems, which are typical of many
fluid systems, frequently utilize a spin-on type filter unit which
is mounted on a filter pad and which includes a filter element to
remove potentially damaging particles from the oil. Mechanical
wear within the engine, the outside environment, and contaminants
introduced accidentally during normal servicing are sources of
particles which may plug lubricating nozzles, severely damage
parts, and create excessive wear on any surfaces relying on a thin
film of lubricating oil for protection.
These systems typically utilize a pump to force oil to
circulate through the filter pad and spin-on filter unit assembly
and then to the moving parts of the engine for lubrication. Oil
is forced through the filter element due to a difference in oil
pressure, i.e., a pressure differential, between the upstream and
downstream sides of the filter element, the pressure on the
upstream side being greater than the pressure on the downstream
side.
Over time, as the spin-on filter unit performs its filtering
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function, the filter element of the spin-on filter unit becomes
plugged by particles removed from the lubricating oil. As the
amount of material filtered from the lubricating oil and retained
by the filter element increases, a greater pressure dif~erential
across the filter element is required to pump sufficient fluid
through the filter element. The amount of lubricating oil which
will pass through the filter element at the maximum pumping
pressure will decrease until flow is insufficient to maintain
proper lubrication of the engine. To prevent tha-t occurrence,
many lubrication systems include a pressure-sensitive bypass valve
which will open when the pressure differential across the filter
element approaches that corresponding to the maximum pumping
pressure, allowing oil to bypass the filter element. This assures
that lubricating oil will continue to reach the moving parts of
the engine but eliminates, at least in part, the filtering
function.
Thus, to assure that sufficient filtered oil continues to
reach the moving parts of the engine, filter units must be
replaced before they become so clogged as to cause the bypass
valve to open. As few lubrication systems are equipped to monitor
the pressure differential across the filter element to determine
when the filter unit should be replaced, the spin-on filter units
are replaced at regular intervals of operation. Although the rate
at which a filter element becomes blocked will vary greatly
depending upon operating conditions for the engine, the filter
unit replacement interval must be selected to be the shortest
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probable time in which excessive blockage may occur to assure
continuous prop~r lubrication system function. This results in
the frequent disposal of filter units before thPir filtering
capacity has been fully utilized, resu:Lting in higher operational
costs.
Some lubrication systems utilizing spin-on filter units
include a pressure detector which senses the pressure only on the
high pressure side, i.e., the upstream side, of the filter. The
detector may be used to operate a filter blockage warning light
when the upstream pressure becomes greater than a predetermined
amount, e.g., approaches maximum pumping pressure. However, the
pressure on the upstream side of the filter element is dependent
on the overall lubrication system pressure and cumulative pressure
drop through the system and is not necessarily indicative of the
filter condition. Thus, such a detector may result in a false
indication of the need to replaca a filter element if the system
becomes blocked downstream of the filter unit.
Few new engines have lubrication systems equipped with a
pressure differential monitor because of the expense of providing
instrumentation to measure pressure on both the upstream and
downstream sides of the filter element and determine the
difference between the two. The difficulty of accommodating such
a monitoring system within the confines of the lubrication systems
is also an important factor. Retrofit of existing engines to
provide for monitoring of the differential pressure across the
filter element of the lubrication system is particularly difficult
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if pressure-sensing devices must be installed within the crankcase
together with leads for app~ priate instrumentation~
u.s. Patent No. 4,783,~256, which is assigned to the assignee
of the present invention, discloses an adapter assembly for a
lubrication system which overcomes the above-described problems
and permits convenient measurement of the pressure differential
across an oil filter during use. The adapter assembly has an
adapter plate which is mounted on an engine between a filter pad
of an engine and an oil filter. The adapter plate is secured to
the filter pad by a cylindrical threaded hub which extends through
the center of the adapter. One end of the hub screws into the
filter pad, and the oil filter screws onto threads formed on the
other end of the hub. The adapter plate has an orifice which
connects between the inlet side and the outlet side of the oil
filter. A differential pressure sensor can be inserted into the
orifice in order to measure the pressure differential between the
inlet and outlet sides of the oil filter. Based on the pressure
differential which is measured by the sensor, it can be determined
when the oil filter has become plugged.
The filter pad of a conventional lubrication system is
generally equipped with a threaded nipple on which an oil filter
can be mounted. In order to retrofit an existing engine with the
adapter assembly disclosed in U.S. Patent No. 4,783,256, it is
necessary to first remove the nipple of the filter pad and replace
it with the threaded hub of the adapter assemblyO The necessity
of removing the nipple makes installation of the adapter assembly
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on an existing lubrication system somewhat troublesome.
~urthermore, there is little standardization of the pitch of the
threads of the hole in the Eilter pad into which the hub of the
adapter assembly is screwed, so in order for the adapter assembly
to be applicable to a large number of different types of
lubrication systems, it is necessary to manufacture many different
hu~s having thread pitches corresponding to the various thread
pitches of the filter pads. In addition, the above-described
adapter plate has no provision for sampling oil from individual
oil passages, such as from an oil inlet passage or an oil outlet
passage. Therefore, it is impossible to sample oil flowing
through the filter during the operation of an engine or to test
the differential pressure sensor without removing it from the
adapter plate.
Accordingly, the present invention provides an adapter
assembly for a fluid system having a spin-on filter unit which has
a base with a fluid inlet and a fluid outlet and a filter element
disposed in a fluid flow path between the inlet and the outlet and
which is attachable to a filter pad having an inlet chamber and an
outlet chamber and a nipple on which the filter unit can be
mounted, the adapter assembly comprising an adapter plate having a
first side, a second side, and an aperture to allow fluid to flow
from the inlet chamber of the filter pad to the inlet of the
filter unit; a hub detachably mounted on the adapter plate and
having a first end and a second end and including means for
detachably connecting the first end of the hub to the nipple of
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the filter pad, means Eor detachably connecting the second end o~
the hub to the filter unit, means for retaining the first side of
the adapter plate in sealed engagement with the filter pad, means
for retaining the base of the filter unit in sealed engagement
with the second side of the adapter plate, and a fluid channel to
allow fluid to flow from the outlet of the filter unit to the
outlet chamber of the filter pad; connecting means for connecting
a differential pressure detector to the adapter plate, the
connecting means including a detector orifice; a firs~ passage
communicating between the aperture in the adapter plate and the
detector orifice; and a second passage communicating between the
channel in the hub and the detector orifice, the adapter plate
having at least one sampling port formed therein which
communicates between an outer surface of the adapter plate and an
inner portion of the adapter plate through which fluid can flow.
The present invention further provides an adapter assembly
for a fluid system having a spin-on filter unit which has a base
with a fluid inlet and a fluid outlet and a filter element
disposed in a fluid flow path between the inlet and the outlet and
which is attachable to a filter pad having an inlet chamber and an
outlet chamber and a nipple on which the filter unit can be
m~unted, the adapter assembly comprising an adapter plate
including a ring-shaped outer portion, a ring-shaped inner portion
which is coaxial with the outer portion, at least one spoke which
extends between the inner and outer portions, a first side and a
second side, a central aperture, and an outer aperture to allow
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fluid to flow from the inlet chamber of the filter pad to the
inlet of the filter unit; a hub detachably mounted inside the
central aperture of the adapter plate and having a first end and a
second end and including means for detachably connecting the first
end of the hub to the nipple of the filter pad, means for
detachably connecting the second end of the hub to the filter
unit, means for retaining the first side of the adapter plate in
sealed engagement with the filter pad, means for retaining the
base of the filter unit in sealed engagement with the second side
of the adapter plate, and a fluid channel to allow fluid to flow
from the outlet of the filter unit to the outlet chamber of the
filter pad; connecting means for connecting a differential
pressure detector to the adapter plate, the connecting means
including a detector orifice which extends into the adapter plate
from a peripheral edge thereof and having an axis extending
radially inward toward the center of the adapter plate; a first
passage communicating between the aperture in the adapter plate
and the detector orifice; a second passage communicating between
the channel in the hub and the detector orifice and extending
radially through the spoke coaxially with respect to the detector
orifice; a first sampling port formed in the adapter plate which
communicates between the aperture in the adapter plate and an
outer surface of the adapter plate; and a second sampling port
formed in the adapter plate which communicates between the channel
in the hub and the outer surface of the adapter plate.
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The present invention thus provides a convenient, effective
and economical way to allow monitoring of the pressure
differential across the filter element of either a new or existing
system utilizin~ a spin-on filter mounted on a ~ilter pad. For
example, the present invention may provide input for an indicator
to be used to warn of clogged filter elements 50 that operation of
an engine with the bypass valve open may be avoided yet filters
may be used to their full capacity for greatest economy.
Other objects, advantages, and aspects of the present
invention will become apparent upon reading the following detailed
description and appended claims and upon reference to the
accompany drawings.
Figure 1 is a longitudinal cross-sectional view of an
exemplary adapter assembly embodying the present invention as
shown mounted between a spin-on filter unit and a filter pad.
Figure 2 is a plan view of the adapter plate of the exemplary
adapter assembly of Figure 1.
As shown in Figure 1, a filter arrangement 10 according to
the present invention has a filter pad 12 which is equipped with a
hollow, threaded nipple 13. The nipple 13 has external threads
formed on both ends thereof. The external threads 25 on the left
end of the nipple 13 in Figure 1 screw into corresponding internal
threads formed in the filter pad 12. The filter pad 12 defines
separate inlet and outlet chambers 23, 24 which are respectively
coupled to inlet and outlet lines or ports (not shown) of a fluid
system such as a hydraulic or lubrication oil system. A flat
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seating surface 30 is formed on an end surface of the filter pad
12 for the adapter assembly to seat against.
The adapter assembly 100 generally comprises a hollow,
threaded hub lol and an adapter plate 102. The hub 101, which may
be fashioned from any suitable rigid impervious material
compatible with the fluid being filtered, has a generally tubular
body 103 defining a central channel 104. A first end 105 of the
hub 101 has internal threads which engage the external threads of
right end of the nipple 13 in Figure 1. A flange 107 extends
radially outwardly from the tubular body 103 at a position near
the second end 106 of the hub 101. Flats are preferably formed
along the periphery of the flange 107, allowing engagement by a
wrench to tighten the hub 101 onto the nipple 13 to an appropriate
degree of torque. A fluid passage 108 extends through the tubular
body 103 at a position between the first end 105 of the hub 101
and the flange 107.
The adapter plate 102, which also may be fashioned from any
suitable rigid impervious material compatible with the fluid being
filtered, preferably has a circular form, as shown in Figure 2,
generally comprising first and second sides 109, llO and a
peripheral edge 111. The adapter plate 102 includes a ring-shaped
inner portion 112 held in fixed coaxial relation with a
ring-shaped outer portion 113 by several spokes 114. The inner
portion 112 defines a central aperture 115 on the inner periphery
of which is formed a circumferentially-extending groove 116. The
outer portion 113 includes first and second end faces 117 and 118.
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The first end face 117, which has mounted on it a circular seal
120, such as the groove and 0-ring arrangement illustrated in
Figure 1, has a diameter similar to that of the seating surface 30
of the filter pad 12. The spokes 114 define several apertures 121
between the inner and outer portions l:L2, 113 of the adapter plate
102.
A conventional filter unit 11 is mounted on the second end
face 118 of the adapter plate 102. The filter unit 11 typically
includes a housing 14 which is sealed to the periphery of an
attachment plate or base 15 and which contains a hollow,
cylindrical filter element 16. The filter element 16 is mounted
concentrically on one side of the base 15 while a seal 20 is
mounted concentrically on the opposite side of the base 15. The
base 15 includes a central outlet hole 21 and several inlet holes
22 positioned between the outlet hole 21 and the seal 20. The
base 15 has internal threads formed thereon which engage with the
external threads formed on the second end 106 of the hub 101.
To allow detection of the differential pressure across the
filter element 16, the adapter plate 102 further includes a
fitting 122 to which a differential pressure detector ~not shown)
may be mounted. In the exemplary adapter assembly 100, the
fitting 122 generally comprises an orifice 123 which is formed in
the peripheral edge 111 of the adapter plate 102 and extends
radially inwardly through the ring-shaped outer portion 113 into a
spoke 114. The detector, which may comprise any suitable
conventional device, such as those available from Pall Corporation
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under the trademarks DELTAMYND or DELTADYNE, may be mounted within
the orifice 123, by bolts (not shown), for example, which
cooperate with tapped holes 12~ in the outer portion 113.
Alternatively, the detector may be mou:nted by means of a retaining
ring or threaded fitting. A first fluid passage 125 communicates
between an outer section of the detector orifice 123 and the space
126 between the inner and outer portio:ns 112, 113 of the adapter
plate 102, which space 126 includes thle apertures 121. A second
fluid passage 127 communicates between the circumferential groove
116 of the central aperture 115 and an inner section of the
detector orifice 123. However, the locations at which the first
and second passages 125, 127 intersect the detector orifice 1~3 as
well as the shape of the detector orifice 123 may vary depending
on the particular differential pressure detector being used.
As shown in Figure 2, the adapter plate 102 is further
equipped with a first sampling port 130 and a second sampling port
131 which enable independent sampling of oil flowing into the
filter unit 11 and oil leaving the filter unit 11. The first
sampling port 130 is a countersunk orifice which extends through
the outer portion 113 of the adapter plate 102. Its outer end
opens onto the peripheral edge 111 and its inner end opens onto
one of the apertures 121. The second sampling port 131 is a
countersunk orifice which is formed in the outer portion 113 and
extends radially through one of the spokes 114. Its outer end
opens onto the peripheral edge 111 of the adapter plate 102 while
its inner end opens onto the circumferential groove 116. The
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second sampling port 131 communicates with the central channel 10
of the hub 101 via the circumferential groove 116 and ~luid
passage 108 of the hub 101. Each sampling port is shaped so as to
receive a corresponding pressure sensox or other measurement
device. When not in use, the sampling ports can be sealed by
suitable, unillustrated plugs.
The sampling ports and the orifice 123 are suitably spaced
around the circumference of the adapter plate 102 so as not to
interfere with one another. For example, in Figure 2, the first
sampling port 130 is disposed 45 on one side of the axis of the
detector orifice 123 and the second sampling port 131 is disposed
120 on the opposite side of the axis of the detector orifice 123.
Although Figure 2 illustrates two sampling ports, it is also
possible to employ a single sampling port which communicates with
either the circumferential groove 116 or with one of the apertures
121.
In a conventional filter arrangement, the filter unit 11
would be mounted directly on the threaded nipple 13. The
exemplary adapter assembly 100 can be easily installed on such a
conventional filter arrangement in the following manner. First,
the spin-on filter unit 11 is removed from the filter pad 12 by
unscrewing it from the threaded nipple 13.
Next, the adapter assembly 100 with the differential pressure
detector installed in the fitting 122 is mounted on the filter pad
12. For example, the first end 105 of the hub 101 may be passed
through the central aperture 115 of the adapter plate 102 until
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the flange 107 engages the ring-shaped inner portion 112 of the
adap-ter plate 102. In this position, the fluid passac~e 10~ of the
hub lO1 communicates between the central channel 104 and the
circumferential groova 116 of the central aperture 115 of the
adapter plate 102, the circumferential groove 116 providing
positive relief from the hub 101 along its axial span. The
internal threads of the first end 105 of the hub 101 can then be
loosely engaged in with the external threads of the right end of
the nipple 13, and the adapter plate 102 can be rotated about the
hub lO1 to locate the fitting 122 in any desired position. With
the adapter plate 102 held in position, the hub 101 can then be
tightened to the nipple 13 by means of the flats on the flange
107. By the action of the flange 107 against the inner
ring-shaped portion 112 of the adapter plate 102, the first side
109 of the adapter plate 102 may be drawn to and retained against
the filter pad 12 with the seal 120 on the adapter plate 102
sufficiently sealed against the seating surface 30 of the filter
pad 12.
In the illustrated embodiment, the adapter plate 102 is
shaped such that it can be reversibly mounted on the filter pad
12. Namely, in Figure 1, the first side 109 of the adapter plate
102 contacts the seating surface 30 of the filter pad 12 and the
second side 110 contacts the base 15 of the filter unit 11.
However, if a circular seal 120 or the like is provided on the
second side 110, the orientation of the adapter plate 102 can be
reversed so that the first side 109 confronts the base 15 of the
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filter unit 11 and the second side llO contacts the seating
surface 30. The ability to reverse the orientation o~ the adapter
plate 102 makes it easier to install on a filter pad 12.
Although an adapter assembly according to the present
invention may have a one-piece structure, the two-piece
arrangement comprising the hub 101 and adapter plate 102 of the
first exemplary assembly 100 is particularly advantageous.
Because the circumferential groove 116 of the central aperture 115
enables the fluid passage 108 in the hub 101 to communicate with
the second fluid passage 127 in the adapter plate 102 regardless
of their relative angular orientation, the adapter plate 102 may
be positioned in any desired angular (i.e., universal) orientation
about the hub 101 independent of the angular orientation of the
hub 101 required to sufficiently tighten the hub 101 to the filter
pad 12. This is important when the available space is limited or
when the differential pressure detector is visible only at a
particular orientation.
Once the exemplary adapter assembly 100 is mounted on the
filter pad 12, the spin-on filter unit 11 may be mounted on the
second side 110 of the adapter plate 102 by engaging the threads
26 on the base 15 of the filter unit ll with the external threads
on the second end 106 of the hub 101. The filter unit 11 is then
tightened onto the hub 101 until the seal 20 on the base 15 of the
filter unit is sufficiently sealed against the second end face 118
of the ring-shaped outer portion 113 of the adapter plate 102.
Replacement of the filter unit 11 simply requires unscrewing the
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old filter unit 11 from the hub 101 of the adapter assembly 100
and then screwing a new filter unit 11 onto the hub 101.
In the preferred mode of operation, fluid at a pressure P1
may be forced into the inlet chamber 23 oE the filter pad 12.
From the inlet chamber ~3, fluid flows through the space 126
between the inner and outer ring-shaped portions 112, 113. Seals
130, such as the groove and 0-ring arrangements, between the hub
101 and the adapter plate 102 on both sides of the circumferential
groove 116 of the central aperture 115 prevent the fluid from
flowing directly into the hub 101 and bypassing the filter element
16. From the space 126, the fluid flows through the inlet holes
22 in the base 15 of the filter unit 11, into the space between
the housing 14 and the filter element 16, and radially inwardly
through the filter element 16 where any harmful particles are
filtered from the fluid and the pressure of the fluid drops from
Pl to P2. Filtrate at pressure P2 then flows from the interior of
the filter element 11 through the central channel 104 of the hub
101 into the outlet chamber 24 of the filter pad 12.
The differential pressure across the filter element 16 may be
detected by the differential pressure detector (not shown) by
means of the adapter assembly 100. The upstream high pressure
fluid is channeled to the differential pressure detector via the
first fluid passage 125, communicating the pressure Pl to the
differential pressure detector. The downstream low pressure fluid
is channeled to the differential pressure detector via the fluid
passage 108 in the hub 101, the circumferential groove 116 of the
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central aperture 115, and the second fluid passage 126 in the
adapier plate 102, communicating the pressure P2 to the
differential pressure detector. Thus, the seals 130 further
isolate the fluid communication between the central channel 104 of
the hub 101 and the detector orifice 123.
The sampling ports 130 and 131 can be advantageously employed
for a variety of purposes. For example, the first sampling port
130 can be used to sample fluid from the upstream side of the
filter unit 11 to determine whether the engine or other device on
which the filter pad 12 is mounted is discharging solid particles,
which are an indication of engine wear. Also, the pressure
between the first sampling port 130 on the upstream side of the
filter unit 11 and the second sampling port 131 on the downstream
side can be measured to determine whether the differential
pressure detector which is installed in the detector orifice 123
is functioning properly. If the sampling p~rts were not provided,
the differential pressure detector could only be inspected after
being removed from the orifice 123. The sampling ports also make
it possible to investigate the viscosity, the temperature, or
other characteristics of the fluid being filtered on either the
upstream or downstream sides of the filter unit 11 during
operation of an engine.
The pitch of the internal threads of the filter pad 12 which
engage with the external threads 25 of the nipple 13 will vary
considerably among fluid systems. However, the adapter plate 102
may be fairly standard for various filter manufacturers.
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Accordingly, only one type of adapter plate may be necessary to
enable the present invention to be employed with a large number of
different fluid systems. Furthermore, since it is not necessary
to remove the nipple 13 fxom the filter pad 12, the adapter
assembly 100 can be installed on an existing fluid system
extremely easily.
While an exemplary adapter assemb:Ly embodying the present
invention have been shown, it will be understood, of course, that
the present invention is not limited to those embodiments.
Modification may be made by those skil:Led in the art, particularly
in light of the foregoing teaching. It is, thereforQ,
contemplated by the appended claims to cover any such modification
which incorporates the essential features of this invention or
encompasses the true spirit and scope of the present invention.
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