Note: Descriptions are shown in the official language in which they were submitted.
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FUEL RECIRCULATION METHOD AND VALVE
BACKGROUND
[0001] The present disclosure is directed toward fuel circuits for
providing fuel to internal
combustion engines such as diesel engines. More particularly, the present
disclosure is directed
toward systems and methods for recirculating fuel returned from an engine and
combining
returned fuel with fuel drawn from a fuel tank to provide an adequate fuel
supply to the engine.
[0002] In cold temperatures, paraffin material, known in the industry
generally as paraffins
and that is suspended in diesel fuel as a part of diesel fuel, tends to
solidify, which causes it to
plug fuel filters. Fuel recirculation valves are operable to mix returning
fuel from the engine with
fuel from the tank (e.g., in about a 9:1 ratio) to warm the fuel provided to
the engine, or more
particularly, to the fuel filter to prevent such plugging. Prior art
recirculation valves are typically
located in a fuel filter container and downstream of the fuel filter such that
the fuel from the tank
is filtered and then mixed with fuel returned from the engine. Thus, to make
changes and
improvements to the recirculation valve, fuel filter redesign may be
necessary. Further,
improvements to the fuel recirculation valve may need to be specifically
tailored to different fuel
supply circuits or fuel filters of various different engine or vehicle
designs.
[0003] In mixing returning fuel from the engine with fuel from the tank,
fuel recirculation
valves can warm the fuel from the tank beyond a desired temperature. This can
in turn affect
performance of the fuel recirculation system components or the engine.
[0004] The discussion above is merely provided for general background
information and is
not intended to be used as an aid in determining the scope of the claimed
subject matter.
SUMMARY
[0005] This Summary and the Abstract are provided to introduce a selection
of concepts that
are disclosed in the Detailed Description in a simplified form. The Summary
and the Abstract are
not intended to identify key features or essential features of the claimed
subject matter, nor are
they intended to be used as an aid in determining the scope of the claimed
subject matter.
100061 Fuel recirculation methods, fuel recirculation circuits and fuel
recirculation valves for
selectively mixing hot return fuel from a diesel engine with fuel from a tank
before providing it
to back to the engine are discussed herein. In one embodiment, a fuel
recirculation valve is
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disclosed for use in a fuel supply circuit that fuel to an engine. The fuel
recirculation valve
includes a body having first inlet configured to receive fuel into the body
from a first source and
a second inlet configured to receive fuel into the body from a second source.
The body also has
an outlet configured to allow fuel to exit the body. A first passage in the
body connects the first
inlet to the outlet. The first passage has a first portion in communication
with the first inlet, a
second portion in communication with the outlet, and a middle portion between
the first portion
and the second portion. The first passage provides a path for fuel from the
first source to travel
from the first inlet to the outlet. A second passage in the body connects the
second inlet to the
first passage at a node positioned between the first inlet and the middle
portion of the first
passage. The second passage provides a path for fuel from the second source to
travel from the
second inlet to the node so that fuel from the second source is capable of
being mixed with the
fuel from the first source at the node.
[0007] In another embodiment, a fuel supply circuit for supplying fuel to
an engine is
disclosed. The fuel supply circuit includes a reservoir for holding fuel and a
fuel pump that has
an engine interface for providing pressurized fuel to the engine and receiving
unused fuel
returned from the engine as well as an inlet for receiving fuel from the
reservoir and an outlet for
returning the unused fuel from the engine to the reservoir. The fuel supply
circuit has an inlet
path between the reservoir and the fuel pump, including a fuel filter package
having a fuel filter
and a fuel recirculation valve located upstream and outside of the fuel filter
package. The fuel
supply circuit also has an outlet path between the fuel pump and the reservoir
including a branch
connection device capable of providing at least a portion of the unused fuel
to the fuel
recirculation valve.
[0008] Yet another embodiment discloses a power machine having a frame, an
engine
mounted to the frame and a fuel supply circuit for supplying fuel to the
engine. The fuel supply
circuit includes a reservoir for holding fuel, a fuel pump for supplying fuel
to and receiving
unused fuel from the engine, an inlet path between the reservoir and the fuel
pump, and an outlet
path between the fuel pump and the reservoir. The inlet path includes a fuel
filter and a fuel
recirculation valve positioned upstream and external to the fuel filter. The
fuel recirculation
valve has a first inlet for receiving fuel from the reservoir, an outlet in
communication with the
fuel filter, and a second inlet. The outlet path includes a branch connection
device capable of
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providing at least a portion of the unused fuel via a conduit to the second
input fuel recirculation
valve.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a block diagram illustrating functional systems of a
representative power
machine on which embodiments of the present disclosure can be advantageously
practiced.
[0010] FIGs. 2-3 illustrate perspective views of a power machine on which a
fuel delivery
system having a fuel recirculation valve according to embodiments discussed
herein can be
advantageously practiced.
[0011] FIG. 4 is a diagrammatic illustration of a fuel delivery circuit
included with a diesel
engine in accordance with exemplary embodiments.
[0012] FIG. 5 is perspective view of a fuel recirculation valve from the
fuel recirculation
circuit shown in FIG. 2 in accordance with exemplary embodiments.
[0013] FIG. 6 is a cross-sectional view of the body of the recirculation
valve shown in FIG. 5
with the valve element removed.
[0014] FIG. 6A is a cross-section of the fuel recirculation valve shown in
FIG. 5 and taken in
perspective view showing the valve element.
[0015] FIG. 7 is an exploded perspective view of the fuel recirculation
valve shown in FIGS.
3 and 4 in accordance with exemplary embodiments.
[0016] FIG. 8 is a cross-sectional side view of the recirculation valve
shown in FIGS. 3-5
and illustrating mixing of fuel recirculated from the engine and fuel from the
fuel tank.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0017] The concepts disclosed in this discussion are described and
illustrated with reference
to exemplary embodiments. These concepts, however, are not limited in their
application to the
details of construction and the arrangement of components in the illustrative
embodiments and
are capable of being practiced or being carried out in various other ways. The
terminology in this
document is used for the purpose of description and should not be regarded as
limiting. Words
such as "including," "comprising," and "having" and variations thereof as used
herein are meant
to encompass the items listed thereafter, equivalents thereof, as well as
additional items.
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[0018]
Disclosed are fuel recirculation methods, fuel recirculation circuits and fuel
recirculation valves for selectively mixing return fuel from a diesel engine
with fuel from a tank
before providing it to back to the engine. In exemplary disclosed embodiments
of fuel
recirculation valves, the valves are configured to selectively mix the fuel in
a controlled manner
using a temperature sensitive actuator within the valve. When the temperature
of the fuel reaches
a certain point, the temperature sensitive actuator causes the valve to narrow
flow pathways and
eventually close to prevent overheating of the fuel. Also, in disclosed
embodiments, the fuel
circulation valve is designed to be separate from the fuel filter and not
integrated into a filter
package. This allows the fuel to be mixed before entering the filter and
allows disclosed fuel
recirculation valves to be added to any fuel supply circuit, regardless of the
type of filter that the
system uses. Thus, disclosed fuel recirculation valves are beneficial for
retrofitting a variety of
existing fuel supply circuits and systems.
[0019]
These concepts can be practiced on various power machines, as will be
described
below. However, the presently disclosed methods, fuel recirculation valves,
and concepts can be
practiced in fuels systems of machines other than power machines. While a
representative power
machine on which the embodiments can be practiced is illustrated in diagram
form in FIG. 1, it
must be understood that disclosed embodiments are not limited to use on the
representative
power machine or on power machines in general.
[0020]
Power machines, for the purposes of this discussion, include a frame, at least
one
work element, and a power source that is capable of providing power to the
work element to
accomplish a work task. One type of power machine is a self-propelled work
vehicle. Self-
propelled work vehicles are a class of power machines that include a frame,
work element, and a
power source that is capable of providing power to the work element. At least
one of the work
elements is a motive system for moving the power machine under power.
[0021]
FIG. 1 illustrates a block diagram illustrates the basic systems of a power
machine
100 upon which the embodiments discussed below can be advantageously
incorporated and can
be any of a number of different types of power machines. The block diagram of
FIG. 1 identifies
various systems on power machine 100 and the relationship between various
components and
systems. As mentioned above, at the most basic level, power machines for the
purposes of this
discussion include a frame, a power source, and a work element. The power
machine 100 has a
frame 110, a power source 120, and a work element 130. Because power machine
100 shown in
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FIG. 1 is a self-propelled work vehicle, it also has tractive elements 140,
which are themselves
work elements provided to move the power machine over a support surface and an
operator
station 150 that provides an operating position for controlling the work
elements of the power
machine. A control system 160 is provided to interact with the other systems
to perform various
work tasks at least in part in response to control signals provided by an
operator.
[0022] Certain work vehicles have work elements that are capable of
performing a dedicated
task. For example, some work vehicles have a lift arm to which an implement
such as a bucket is
attached such as by a pinning arrangement. The work element, i.e., the lift
arm can be
manipulated to position the implement for the purpose of performing the task.
The implement, in
some instances can be positioned relative to the work element, such as by
rotating a bucket
relative to a lift arm, to further position the implement. Under normal
operation of such a work
vehicle, the bucket is intended to be attached and under use. Such work
vehicles may be able to
accept other implements by disassembling the implement/work element
combination and
reassembling another implement in place of the original bucket. Other work
vehicles, however,
are intended to be used with a wide variety of implements and have an
implement interface such
as implement interface 170 shown in FIG. 1. At its most basic, implement
interface 170 is a
connection mechanism between the frame 110 or a work element 130 and an
implement, which
can be as simple as a connection point for attaching an implement directly to
the frame 110 or a
work element 130 or more complex, as discussed below.
[0023] On some power machines, implement interface 170 can include an
implement carrier,
which is a physical structure movably attached to a work element. The
implement carrier has
engagement features and locking features to accept and secure any of a number
of implements to
the work element. One characteristic of such an implement carrier is that once
an implement is
attached to it, it is fixed to the implement (i.e. not movable with respect to
the implement) and
when the implement carrier is moved with respect to the work element, the
implement moves
with the implement carrier. The term implement carrier as used herein is not
merely a pivotal
connection point, but rather a dedicated device specifically intended to
accept and be secured to
various different implements. The implement carrier itself is mountable to a
work element 130
such as a lift arm or the frame 110. Implement interface 170 can also include
one or more power
sources for providing power to one or more work elements on an implement. Some
power
machines can have a plurality of work element with implement interfaces, each
of which may,
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but need not, have an implement carrier for receiving implements. Some other
power machines
can have a work element with a plurality of implement interfaces so that a
single work element
can accept a plurality of implements simultaneously. Each of these implement
interfaces can, but
need not, have an implement carrier.
[0024] Frame 110 includes a physical structure that can support various
other components
that are attached thereto or positioned thereon. The frame 110 can include any
number of
individual components. Some power machines have frames that are rigid. That
is, no part of the
frame is movable with respect to another part of the frame. Other power
machines have at least
one portion that is capable of moving with respect to another portion of the
frame. For example,
excavators can have an upper frame portion that rotates with respect to a
lower frame portion.
Other work vehicles have articulated frames such that one portion of the frame
pivots with
respect to another portion for accomplishing steering functions.
[0025] Frame 110 supports the power source 120, which is configured to
provide power to
one or more work elements 130 including the one or more tractive elements 140,
as well as, in
some instances, providing power for use by an attached implement via implement
interface 170.
Power from the power source 120 can be provided directly to any of the work
elements 130,
tractive elements 140, and implement interfaces 170. Alternatively, power from
the power source
120 can be provided to a control system 160, which in turn selectively
provides power to the
elements that capable of using it to perform a work function.
[0026] Power sources for power machines typically include an engine such as
an internal
combustion engine and a power conversion system such as a mechanical
transmission or a
hydraulic system that is configured to convert the output from an engine into
a form of power
that is usable by a work element. Other types of power sources can be
incorporated into power
machines, including electrical sources or a combination of power sources,
known generally as
hybrid power sources. In exemplary embodiments, power source 120 includes a
diesel engine
and a fuel supply circuit which uses a fuel recirculation valve as described
herein to mix return
fuel from the engine with fuel from the fuel tank.
[0027] FIG. 1 shows a single work element designated as work element 130,
but various
power machines can have any number of work elements. Work elements are
typically attached to
the frame of the power machine and movable with respect to the frame when
performing a work
task. In addition, tractive elements 140 are a special case of work element in
that their work
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function is generally to move the power machine 100 over a support surface.
Tractive elements
140 are shown separate from the work element 130 because many power machines
have
additional work elements besides tractive elements, although that is not
always the case. Power
machines can have any number of tractive elements, some or all of which can
receive power
from the power source 120 to propel the power machine 100. Tractive elements
can be, for
example, track assemblies, wheels attached to an axle, and the like. Tractive
elements can be
mounted to the frame such that movement of the tractive element is limited to
rotation about an
axle (so that steering is accomplished by a skidding action) or,
alternatively, pivotally mounted
to the frame to accomplish steering by pivoting the tractive element with
respect to the frame.
[0028] Power machine 100 includes an operator station 150 that includes an
operating
position from which an operator can control operation of the power machine. In
some power
machines, the operator station 150 is defined by an enclosed or partially
enclosed cab. Some
power machines on which the disclosed embodiments may be practiced may not
have a cab or an
operator compartment of the type described above. For example, a walk behind
loader may not
have a cab or an operator compartment, but rather an operating position that
serves as an
operator station from which the power machine is properly operated. More
broadly, power
machines other than work vehicles may have operator stations that are not
necessarily similar to
the operating positions and operator compartments referenced above. Further,
some power
machines such as power machine 100 and others, whether or not they have
operator
compartments or operator positions, may be capable of being operated remotely
(i.e. from a
remotely located operator station) instead of or in addition to an operator
station adjacent or on
the power machine. This can include applications where at least some of the
operator controlled
functions of the power machine can be operated from an operating position
associated with an
implement that is coupled to the power machine. Alternatively, with some power
machines, a
remote control device can be provided (i.e. remote from both of the power
machine and any
implement to which is it coupled) that is capable of controlling at least some
of the operator
controlled functions on the power machine.
[0029] FIGs. 2-3 illustrate a loader 200, which is one particular example
of a power machine
of the type illustrated in FIG. 1 where the embodiments discussed below can be
advantageously
employed. Loader 200 is a track loader and more particularly, a compact
tracked loader. A track
loader is a loader that has endless tracks as tractive elements (as opposed to
wheels). Other
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loaders can have wheels instead of tracks. Track loader 200 is one particular
example of the
power machine 100 illustrated broadly in FIG. 1 and discussed above. To that
end, features of
loader 200 described below include reference numbers that are generally
similar to those used in
FIG. 1. For example, loader 200 is described as having a frame 210, just as
power machine 100
has a frame 110. Track loader 200 is described herein to provide a reference
for understanding
one environment on which the embodiments described below related to track
assemblies and
mounting elements for mounting the track assemblies to a power machine may be
practiced. The
loader 200 should not be considered limiting especially as to the description
of features that
loader 200 may have described herein that are not essential to the disclosed
embodiments and
thus may or may not be included in power machines other than loader 200 upon
which the
embodiments disclosed below may be advantageously practiced. Unless
specifically noted
otherwise, embodiments disclosed below can be practiced on a variety of power
machines, with
the track loader 200 being only one of those power machines. For example, some
or all of the
concepts discussed below can be practiced on many other types of track work
vehicles such as
various other loaders, excavators, trenchers, and dozers, to name but a few
examples.
[0030]
Loader 200 includes frame 210 that supports a power system 220, the power
system
being capable of generating or otherwise providing power for operating various
functions on the
power machine. Power system 220 illustratively includes an internal combustion
engine of the
type that can benefit from a fuel supply circuit that uses a fuel
recirculation valve to mix return
fuel from the engine with fuel from the fuel tank before supplying the mixed
fuel to the engine.
Frame 210 also supports a work element in the form of a lift arm structure 230
that is powered
by the power system 220 and is capable of performing various work tasks. As
loader 200 is a
work vehicle, frame 210 also supports a traction system 240, which is also
powered by power
system 220 and is capable of propelling the power machine over a support
surface. The lift arm
structure 230 in turn supports an implement carrier interface 270, which
includes an implement
carrier 272 that is capable of receiving and securing various implements to
the loader 200 for
performing various work tasks and power couplers 274, which are provided to
selective provide
power to an implement that might be connected to the loader. The loader 200
can be operated
from within a cab 250 from which an operator can manipulate various control
devices 260 to
cause the power machine to perform various functions. Cab 250 can be pivoted
back about an
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axis that extends through mounts 254 to access components as needed for
maintenance and
repair.
[0031] Various power machines that are capable of including and/or
interacting with the
embodiments discussed below can have various different frame components that
support various
work elements. The elements of frame 210 discussed herein are provided for
illustrative purposes
and should not be considered to be the only type of frame that a power machine
on which the
embodiments can be practiced can employ. Frame 210 of loader 200 includes an
undercarriage
or lower portion 211 of the frame and a mainframe or upper portion 212 of the
frame that is
supported by the undercarriage. The mainframe 212 of loader 200 is attached to
the
undercarriage 211 such as with fasteners or by welding the undercarriage to
the mainframe.
Mainframe 212 includes a pair of upright portions 214A and 214B located on
either side and
toward the rear of the mainframe that support lift arm structure 230 and to
which the lift arm
structure 230 is pivotally attached. The lift arm structure 230 is
illustratively pinned to each of
the upright portions 214A and 214B. The combination of mounting features on
the upright
portions 214A and 214B and the lift arm structure 230 and mounting hardware
(including pins
used to pin the lift arm structure to the mainframe 212) are collectively
referred to as joints 216A
and 216B (one is located on each of the upright portions 214) for the purposes
of this discussion.
Joints 216A and 216B are aligned along an axis 218 so that the lift arm
structure is capable of
pivoting, as discussed below, with respect to the frame 210 about axis 218.
Other power
machines may not include upright portions on either side of the frame, or may
not have a lift arm
structure that is mountable to upright portions on either side and toward the
rear of the frame. For
example, some power machines may have a single arm, mounted to a single side
of the power
machine or to a front or rear end of the power machine. Other machines can
have a plurality of
work elements, including a plurality of lift arms, each of which is mounted to
the machine in its
own configuration. Frame 210 also supports a pair of tractive elements 219A
and 219B on either
side of the loader 200, which on loader 200 are track assemblies.
[0032] The lift arm structure 230 shown in FIG. 1 is one example of many
different types of
lift arm structures that can be attached to a power machine such as loader 200
or other power
machines on which embodiments of the present discussion can be practiced. The
lift arm
structure 230 has a pair of lift arms 234 that are disposed on opposing sides
of the frame 210. A
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first end of each of the lift arms 234 is pivotally coupled to the power
machine at joints 216 and a
second end 232B of each of the lift arms is positioned forward of the frame
210 when in a
lowered position as shown in FIG. 2. The lift arm structure 230 is moveable
(i.e. the lift arm
structure can be raised and lowered) under control of the loader 200 with
respect to the frame
210. That movement (i.e. the raising and lowering of the lift arm structure
230) is described by a
travel path, shown generally by arrow 237. For the purposes of this
discussion, the travel path
237 of the lift arm structure 230 is defined by the path of movement of the
second end 232B of
the lift arm structure.
[0033]
Each of the lift arms 234 of lift arm structure 230 as shown in FIG. 2
includes a first
portion 234A and a second portion 234B that is pivotally coupled to the first
portion 234A. The
first portion 234A of each lift arm 234 is pivotally coupled to the frame 210
at one of the joints
216 and the second portion 234B extends from its connection to the first
portion 234A to the
second end 232B of the lift arm structure 230. The lift arms 234 are each
coupled to a cross
member 236 that is attached to the first portions 234A. Cross member 236
provides increased
structural stability to the lift arm structure 230. A pair of actuators 238,
which on loader 200 are
hydraulic cylinders configured to receive pressurized fluid from power system
220, are pivotally
coupled to both the frame 210 and the lift arms 234 at pivotable joints 238A
and 238B,
respectively, on either side of the loader 200. The actuators 238 are
sometimes referred to
individually and collectively as lift cylinders. Actuation (i.e., extension
and retraction) of the
actuators 238 cause the lift arm structure 230 to pivot about joints 216 and
thereby be raised and
lowered along a fixed path illustrated by arrow 237. Each of a pair of control
links 217 are
pivotally mounted to the frame 210 and one of the lift arms 232 on either side
of the frame 210.
The control links 217 help to define the fixed travel path of the lift arm
structure 230. The lift
arm structure 230 shown in FIG. 2 is representative of one type of lift arm
structure that may be
coupled to the power machine 100. Other lift arm structures, with different
geometries,
components, and arrangements can be pivotally coupled to the loader 200 or
other power
machines upon which the embodiments discussed herein can be practiced without
departing from
the scope of the present discussion. For example, other machines can have lift
arm structures
with lift arms that each has one portion (as opposed to the two portions 234A
and 234B of lift
arm 234) that is pivotally coupled to a frame at one end with the other end
being positioned in
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front of the frame. Other lift arm structures can have an extendable or
telescoping lift arm. Still
other lift arm structures can have several (i.e. more than two) portions
segments or portions.
Some lift arms, most notably lift arms on excavators but also possible on
loaders, may have
portions that are controllable to pivot with respect to another segment
instead of moving in
concert (i.e. along a pre-determined path) as is the case in the lift arm
structure 230 shown in
FIG. 2. Some power machines have lift arm structures with a single lift arm,
such as is known in
excavators or even some loaders and other power machines. Other power machines
can have a
plurality of lift arm structures, each being independent of the other(s).
[0034] Implement interface 270 is provided at a second end 234B of the arm
234. The
implement interface 270 includes an implement carrier 272 that is capable of
accepting and
securing a variety of different implements to the lift arm 230. Such
implements have a machine
interface that is configured to be engaged with the implement carrier 272. The
implement carrier
272 is pivotally mounted to the second end 234B of the arm 234. Implement
carrier actuators are
operably coupled the lift arm structure 230 and the implement carrier 272 and
are operable to
rotate the implement carrier with respect to the lift arm structure.
[0035] The implement interface 270 also includes an implement power source
274 available
for connection to an implement on the lift arm structure 230. The implement
power source 274
includes pressurized hydraulic fluid port to which an implement can be
coupled. The pressurized
hydraulic fluid port selectively provides pressurized hydraulic fluid for
powering one or more
functions or actuators on an implement. The implement power source can also
include an
electrical power source for powering electrical actuators and/or an electronic
controller on an
implement. The implement power source 274 also exemplarily includes electrical
conduits that
are in communication with a data bus on the excavator 200 to allow
communication between a
controller on an implement and electronic devices on the loader 200.
[0036] The lower frame 211 supports and has attached to it a pair of
tractive elements 219A
and 219B. Each of the tractive elements 219A and 219B has a track frame that
is coupled to the
lower frame 211. The track frame supports and is surrounded by an endless
track, which rotates
under power to propel the loader 200 over a support surface. Various elements
are coupled to or
otherwise supported by the track frame for engaging and supporting the endless
track and cause
it to rotate about the track frame. For example, a sprocket is supported by
the track frame and
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engages the endless track to cause the endless track to rotate about the track
frame. An idler is
held against the track by a tensioner (not shown) to maintain proper tension
on the track. The
track frame also supports a plurality of rollers, which engage the track and,
through the track, the
support surface to support and distribute the weight of the loader 200.
[0037] Loaders can include human-machine interfaces including display
devices that are
provided in the cab to give indications of information relatable to the
operation of the power
machines in a form that can be sensed by an operator, such as, for example
audible and/or visual
indications. Audible indications can be made in the form of buzzers, bells,
and the like or via
verbal communication. Visual indications can be made in the form of graphs,
lights, icons,
gauges, alphanumeric characters, and the like. Displays can be dedicated to
provide dedicated
indications, such as warning lights or gauges, or dynamic to provide
programmable information,
including programmable display devices such as monitors of various sizes and
capabilities.
Display devices can provide diagnostic information, troubleshooting
information, instructional
information, and various other types of information that assists an operator
with operation of the
power machine or an implement coupled to the power machine. Other information
that may be
useful for an operator can also be provided.
[0038] The description of power machine 100 and loader 200 above is
provided for
illustrative purposes, to provide illustrative environments on which the
embodiments discussed
below can be practiced. While the embodiments discussed can be practiced on a
power machine
such as is generally described by the power machine 100 shown in the block
diagram of FIG. 1
and more particularly on a loader such as track loader 200, unless otherwise
noted or recited, the
concepts discussed below are not intended to be limited in their application
to the environments
specifically described above.
[0039] FIG. 4 is a diagram of a portion of a power system 300 of the type
that can be used
with power machines such as power machines 100 and 200 discussed above
according to one
illustrative embodiment. Power system 300 includes a diesel engine 302 and a
fuel supply circuit
304 for supplying fuel to the engine 302. As shown in FIG. 4, circuit 304
includes a fuel pump
310 that receives fuel from an input path 305 at a first inlet 312 and returns
fuel from the engine
via a first outlet 314 through an outlet path 315. Other inlets and/or outlets
of pump 310, for
example those in communication with engine 302, are not discussed here. Pump
inlet 312
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receives fuel from a pump inlet line 322 that is connected directly to, or in
series with, an output
of a fuel filter 320. A certain portion of the fuel that is provided to the
engine 302 is not burned,
but is returned to the fuel pump 310. This unused fuel is returned by pump 310
through pump
outlet 314 coupled to a pump outlet line 324. The returned unused fuel is
warmed by its passage
through the engine 302. A branch connection device 326 such as a tee is
coupled to pump outlet
line 324 splits the returning fuel between a pump return line 328 and a fuel
recirculation valve
input line 334 that is in communication with a fuel recirculation valve 340.
Fuel not returned to
the fuel recirculation valve 340 is returned to a fuel tank or reservoir 332
through pump return
line 328 via a cooler 330 in some embodiments, although other embodiments may
not have a
cooler. Fuel recirculation valve 340 includes a first inlet 341 in
communication with a fuel tank
332 via a fuel tank inlet line 342. Fuel recirculation valve 340 also includes
a second inlet 343 in
communication with fuel recirculation input line 334. An outlet 344 of the
fuel recirculation
valve 340 is coupled to an output line 345 in fluid communication with an
input line 348 of fuel
filter 320. In some embodiments, a primer bulb or other device 346 can be
included between fuel
recirculation valve 340 and fuel filter 320 to at least initially encourage
flow of fuel from fuel
recirculation valve 340 into fuel filter 320. In other embodiments, no primer
bulb is provided.
The fuel supply circuit 304 is one example of a fuel supply circuit that can
incorporate fuel
recirculation circuits and fuel recirculation valves of the type discussed
herein. Other fuel supply
circuits can have different components or arrangements of components that are
not part of the
specific portions of the fuel supply circuits that make up the fuel
recirculation schemes that are
part of this disclosure.
[0040] The fuel recirculation valve 340 operates in the fuel supply circuit
304 to receive fuel
from two different sources (i.e. a fuel tank and a return from an engine), mix
the fuel, and
provide the mixed fuel to the engine. In the fuel supply circuit 304 shown in
FIG. 4, the fuel
recirculation valve 340 is advantageously located upstream from the fuel
filter 320 so that mixed
fuel is provided to the inlet of the filter. Fuel returned from the engine is
already filtered and is
usually warmer than fuel provided from the fuel tank.
[0041] It is known that at low temperatures, diesel fuel can become cloudy
as paraffin in the
fuel tends to solidify. A portion of the return fuel from the engine, being
warmer than fuel from
the fuel tank, is advantageously mixed with fuel from the tank to provide a
warmer fuel to the
fuel filter 320 and, eventually, the engine 302. By mixing the fuel prior to
the fuel filter 320,
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warmer fuel is provided to the filter, advantageously reducing the possibility
of clogging the
filter with paraffin. While it is advantageous to provide fuel above a certain
temperature to
reduce the likelihood of paraffin solidifying in the fuel and clogging the
filter, it is also known
that when fuel gets too hot, it can damage the engine. Therefore, as described
below, the fuel
recirculation valve 340 has a valve element to selectively provide or meter
the amount of return
fuel that is provided for mixing with fuel from the fuel tank to reduce, when
necessary, the
temperature of the fuel provided to the engine.
[0042] FIG. 5 is a perspective illustration of a fuel recirculation valve
340 according to one
illustrative embodiment. In one example embodiment, fuel recirculation valve
340 includes a
main housing portion or body 405 and a top portion or cap 410 that is attached
to the body. Body
405 includes the inlet 341 and the outlet 344 of the fuel recirculation valve
340 through which
fuel from the fuel tank 332 is received and provided downstream in the fuel
supply circuit. The
second inlet 343, in this embodiment, is formed into cap 410 (although it need
not be) to provide
a path for return fuel from the engine 302 into the fuel recirculation valve.
Outlet 344 is
configured to be coupled in fluid communication, either directly or through
elements such as an
actuating element (e.g. primer bulb 346), to the inlet of fuel filter 320.
[0043] FIGs. 6, 6A, and 7 provide detailed illustrations of fuel
recirculation valve 340 in
accordance with exemplary embodiments. FIG. 6 shows a cross-section of a
portion of the fuel
recirculation valve 340 including the body 405 and the cap 410 with internal
components
removed, FIG. 6A shows a perspective view of fuel recirculation valve 340 in
cross section, and
FIG. 7 is an exploded perspective view of the valve. The body 405 includes a
passage 412
between the first inlet 341 and the outlet 344. Passage 412 has an inlet
portion 414, an outlet
portion 416, and a middle portion 418 between the inlet portion and the outlet
portion. The
middle portion 418 is widened to allow a temperature sensitive actuator 442 to
be seated within
the passage 412 without completely blocking the passage. That is, fuel is
allowed to pass around
the temperature sensitive actuator 442 as it moves through middle portion 418
of the passage
412. As will be discussed below, as the fuel passes around the temperature
sensitive actuator
442, the temperature sensitive actuator responds to the temperature of the
fuel.
[0044] The fuel recirculation valve 340 also includes a return path 422
that extends from the
second inlet 343 to a node 424 at which the return path joins the inlet
portion 414 of passage 412.
The return path includes a first portion 426 and a second portion 428, the
first portion having a
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first end in communication with the second inlet 343 and the second portion
428 being in
communication with the with the passage 412 at node 424. In between the first
portion 426 and
the second portion 428 is a valve cavity 430 in which a valve member or
actuator 440 (shown in
FIG. 7) is placed to be selectively actuated to allow return fuel into the
second portion 428. The
valve member, as will be discussed in more detail below, is moveable based on
fuel temperature
to regulate the amount, if any, of return fuel that is provided into the
second portion 428 and
eventually be mixed with fuel from the tank at node 424.
[0045]
FIG. 6A and 7 show the fuel recirculation valve 340 including the valve member
or
actuator 440 that is seated within the valve cavity 430 (shown in an exploded
view in FIG. 7).
The valve member 440 includes temperature sensitive element 442 and a blocking
member 444.
The blocking member 444 is moveable within the valve cavity 430 under
influence of the
temperature sensitive element 442 to regulate the amount of return fuel that
passes from the first
portion 426 to the second portion 428 of the return path 422. The temperature
sensitive element
442 has a body 446 with a temperature sensitive material such as wax located
within the body
that expands as the temperature expands to act against a plunger 448. As the
temperature
sensitive material expands, the plunger 448 extends out of the body 446 to act
against the
blocking member 444. The blocking member 444 is biased to an open or
unactuated position by
a biasing member 450, which is a spring that acts against the cover 410 and
the blocking member
444. A spring 452 acts against the blocking member 444 and a collar 454 that
is solidly coupled
to the plunger 448. The spring rate of spring 452 is such that it allows the
plunger 448 to move
the blocking member 444 against biasing member 450 until the blocking member
444 is fully
seated in a closed or actuated position and also collapse to allow the plunger
to over travel within
the valve member so that the valve body 405 and the connection between the
valve body and the
cover 410 is not compromised. A first sealing member 456 is provided to seal
first portion 426
when the blocking member 444 is fully extended in a fully actuated position
toward the first
portion to prevent fuel from moving from the first portion to the second
portion 428 of the return
path 422. A second sealing member 458 is provided to prevent fuel flow between
the valve
cavity 430 and the middle portion 418 of the passage 412. In the embodiments
shown herein,
first and second sealing members are 0-rings. In other embodiments, other
types of sealing
members can be used.
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[0046] In operation, as shown in FIG. 8, the fuel recirculation valve 340
operates to allow
return fuel (identified as "Hot Fuel") to mix with fuel from the tank (shown
as "Cold Fuel") to
mix at node 424, prior to entering the middle portion 418 of the passage 412.
By mixing the fuel
prior to entering the middle portion 418, the actuator is controlled by
sensing the mixed
temperature and not the temperature of the returned fuel, thereby provided a
better control of the
temperature of the fuel being provided to the filter and then to the engine.
100471 The disclosed fuel recirculation valve embodiments also
advantageously mix the fuel
supplies in the fuel recirculation valve before encountering the actuator. By
mixing the fuel prior
to encountering the filter, the disclosed fuel recirculation valves can be
added to any fuel system
with any fuel filter and placed in the fuel supply circuit prior to (upstream
of) the fuel filter. In
addition, because the fuel is mixed before, instead of in, the filter, the
likelihood that cold fuel
would be introduced into the filter, and thereby plug the filter or at least
part of it, is minimized.
This is particularly important in the first moments after the engine 302 is
started in a cold
weather application.
100481 Although the present invention has been described with reference to
preferred
embodiments, workers skilled in the art will recognize that changes may be
made in form and
detail without departing from the spirit and scope of the invention. For
example, while in
example embodiments a wax element type of temperature element is shown, in
other
embodiments other types of temperature elements can be used to move a valve
element
responsive to, or as a function of, temperature of a mixed flow in order to
restrict or stop a flow
of hot fuel into the mixing region. Other such modifications are also within
the scope of this
disclosure.
