Information
-
Patent Grant
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6817343
-
Patent Number
6,817,343
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Date Filed
Wednesday, April 23, 200321 years ago
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Date Issued
Tuesday, November 16, 200419 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 123 497
- 123 446
- 123 456
- 123 17917
- 123 198 D
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International Classifications
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Abstract
Particularly in a relatively large engine that has been inactive for a substantial period of time at a cold temperature, the pressure within a fuel system may decrease. Prior to initiation of engine start-up, fuel pumps that are operably coupled to the engine cannot pressurize and/or circulate fuel within the fuel system. Thus, the time required to supply the high pressure lines with fuel pressure sufficient to start and maintain the engine can be unreasonably delayed. In order to decrease the delay in starting the engine, the present invention includes an electronic control module that includes a priming algorithm. The priming algorithm is operable to activate an electrically powered fuel pump when a fuel system is in an unprimed state. The electronic control module is in communication with at least one sensor that is operable to sense the state of the fuel system.
Description
TECHNICAL FIELD
The present invention relates generally to fuel systems, and more specifically to a method of priming fuel systems using an electronic control system.
BACKGROUND
It is known in the art that when an engine is shut down and allowed to remain inactive for a period of time, fuel pressure within the engine's fuel system will decay. In addition, when the engine has remained inactive for a relatively long period or when the engine is shut down hot and allowed to cool to ambient air temperature on a cold day, the fuel will contract allowing vapor and/or air bubbles to form within the fuel system. Further, when the fuel system is drained for maintenance purposes, the fuel within the system must be replaced. Thus, in order to re-start the engine, the fuel system must be primed with fuel, and the pressure within the fuel system must be raised.
In many fuel systems, the pressure within the fuel system is raised by a high pressure pump. A fuel transfer pump supplies the fuel to the high pressure pump, and the high pressure pump pressurizes the fuel and delivers it to a common rail. It is known in the art that, in order to effectively operate the high pressure pump, the fuel flowing from the fuel transfer pump into the high pressure pump must be at a threshold inlet pressure. Once the fuel enters the high pressure pump, the high pressure pump must further raise the pressure of the fuel to an outlet valve opening pressure in order to permit the flow of fuel from the high pressure pump to the common rail. The high pressure pump can then prime the common rail with fuel and raise the pressure of the common rail to injection pressures.
Often, the high pressure pump and the fuel transfer pump are operably coupled to the engine. Thus, once engine cranking has begun, it takes time for the fuel transfer pump to raise the pressure of the fuel being supplied to the high pressure pump to the threshold inlet pressure. Moreover, once engine cranking has begun, it takes time for the high pressure pump to create pressure sufficient to open the outlet valve of the high pressure pump. Because the priming of the common rail is dependent on the output of the high pressure pump which in return is dependent on the output of the fuel transfer pump, the engine crank time is increased by the high pressure pump and the fuel transfer pump.
Over the years, engineers have developed various strategies for priming a fuel system and reducing engine cranking time. One such strategy is the use of electrically powered priming pumps. For instance, the fuel system shown in U.S. Pat. No. 5,878,718, issued to Rembold et al., on Mar. 9, 1999, includes an electrically powered fuel transfer pump that also acts as the priming pump. Upon initiation of the engine, the Rembold pump is electrically activated and begins supplying fuel to a mechanical high pressure pump and fuel common rail. However, if pressure sensors sense that the fuel system is in an unprimed state, an electronically controlled valve will be activated in order to increase the delivery of the fuel transfer pump. The fuel transfer pump will then act as the priming pump and deliver fuel to the common rail via a fuel connection line that bypasses the high pressure pump that is operably coupled to the engine. By bypassing the high pressure pump, fuel can be delivered to the common rail without being hindered by the high pressure pump. When the high pressure pump is fully activated and is supplying high pressure fuel to the common rail, the electronically controlled valve is returned to its normal engine operating position, reducing the delivery from the electrically powered pump. The electrically powered pump will act as the fuel transfer pump and deliver fuel to the common rail via the high pressure pump, rather than by bypassing the high pressure pump.
Although the Rembold pump illustrates one strategy for reducing engine crank time and priming the fuel system, there is room for improvement. For instance, in larger engines, such as those used in conjunction with generators, marine applications, and locomotives, it is often inefficient and impractical to use an electrically-powered fuel transfer pump. The larger the engine, the larger the fuel transfer pump, and thus, the more energy required to operate the fuel transfer pump. Often, hand priming pumps or manually activated priming pumps are used. Further, for engines with specific applications, such as engines used with generators in case of emergencies, the system should be able to prime the common rail prior to initiation of the engine start-up in order to assure relatively quick engine starts. For instance, in a hospital where the primary power source is interrupted, the engine used in conjunction with the generator must be able to start operating and providing mechanical energy to the generator within a specified short period in order to maintain the operation of the hospital's equipment and to meet federal regulations. The Rembold pump that is not activated until initiation of the engine start cannot assure a primed common rail in an inactive engine.
The present invention is directed to overcoming one or more of the problems set forth above.
SUMMARY OF THE INVENTION
In one aspect of the present invention, a fuel system includes a first fuel pump that is electrically powered and in communication with an electronic control module. A second fuel pump is operably coupled to an engine. The electronic control module includes a priming algorithm that is operable to activate the first fuel pump when the fuel system is in an unprimed state.
In another aspect of the present invention, a control system includes an electronic control module in communication with at least one sensor operable to sense a state of the fuel system. The electronic control module includes a priming algorithm that is operable to activate an electrically powered fuel pump when the state of the fuel system is unprimed.
In yet another aspect of the present invention, a fuel system is primed by first determining whether the fuel system is in an unprimed state. If the fuel system is in an unprimed state, an electrically powered pump is activated via an electronic control module.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a schematic representation of a fuel system, according to the present invention; and
FIG. 2
is a flow chart of a priming algorithm, according to the present invention.
DETAILED DESCRIPTION
Referring to
FIG. 1
, there is shown a schematic representation of a fuel system
10
, according to the present invention. The fuel system
10
circulates fuel between a fuel tank
12
and an engine
11
via a supply line
13
and a return line
14
. Within the fuel supply line
13
, there are at least two pumps, and preferably three pumps. A first fuel pump, being priming pump
16
, is electrically powered and is in communication with an electronic control module
24
via a pump communication line
23
. The priming pump
16
is positioned in a priming portion
13
c
of the supply passage
13
. A second fuel pump, being fuel transfer pump
17
, is operably coupled to the engine
11
via a mechanical linkage that could include gears and rotating shafts. Although a pressure regulator could be included in a separate housing downstream from fuel transfer pump
17
, the present invention illustrates the fuel transfer pump
17
including a pressure regulator of a conventional type fluidly connected to the fuel tank
12
via regulator return line
18
. The pressure regulator regulates the delivery of fuel from the fuel transfer pump
17
and can assist in removing air from the fuel.
The fuel transfer pump
17
and the priming pump
16
are positioned parallel to one another such that fuel drawn from the fuel tank
12
will pass through either the fuel transfer pump
17
or the priming pump
16
after passing through a first fuel filter
15
. Although the fuel transfer pump
17
and the priming pump
16
preferably share a portion of the supply line
13
extending from the fuel tank
12
, it should be appreciated that each pump
17
and
16
could be fluidly connected to the fuel tank
12
via its own supply line with its own fuel filter. In the preferred embodiment, the output from priming pump
16
bypasses the pumping portion of fuel transfer pump
17
; however, the fluid connection itself is located within the housing for fuel transfer pump
17
. It should further be appreciated that the priming portion
13
c
could connect with the supply line l
3
a
upstream from the fuel transfer pump
17
rather than via a portion of the fuel transfer pump
17
. A first valve
27
and a second valve
29
prohibit the reverse flow of fuel to and from either the priming pump
16
and the fuel transfer pump
17
. Although the valves
27
and
29
could be various types, the present invention illustrates valves
27
and
29
as conventional check valves. The first valve
27
is positioned within the priming portion
13
c
and prevents the back flow of fuel into the priming portion
13
c
of the supply line
13
. The second valve
29
is positioned upstream from the fuel transfer pump
17
, and prevents the back flow of fuel through the upstream portion
13
a
of the supply line
13
.
A third fuel pump, being high pressure pump
20
, is positioned downstream from both the fuel transfer pump
17
and the priming pump
16
. The third fuel pump
20
is operably coupled to the engine
11
via a conventional mechanical linkage that could include gears and rotating shafts. The high pressure pump
20
includes an outlet valve that will allow fuel to flow from the high pressure pump
20
when the pressure within the high pressure pump
20
has reached an outlet valve opening pressure. The high pressure pump
20
also includes a threshold inlet pressure at which the pump
20
operates effectively. The threshold inlet pressure is the pressure of the fuel flowing into the high pressure pump
20
. A second fuel filter
19
providing an intense filtration of the fuel is positioned within the supply line
13
downstream from the fuel transfer pump
17
and the priming pump
16
and upstream from the high pressure pump
20
. Although three pumps are preferred, it should be appreciated that the present invention also contemplates a fuel system with more than three pumps or with only two fuel pumps. In the fuel system with two pumps, an electrically powered fuel transfer pump is appropriately plumbed and controlled to circulate fuel to the high pressure pump
20
and also serve as the priming pump of the present invention.
The fuel system
10
preferably includes a bypass line
21
that fluidly connects an upstream portion
13
a
of the supply line
13
to a downstream portion
13
b
of the supply line
13
. Because the upstream portion
13
a
and the downstream portion
13
b
are separated by the high pressure pump
20
, fuel flowing through the bypass line
21
bypasses the high pressure pump
20
. A check valve
22
is positioned within the bypass line
21
. The check valve
22
is preferably biased to the closed position by a spring. However, it should be appreciated that the valve
22
could be of various types and of varying complexity. Those skilled in the art will also appreciate that in an alternative version, the affect of check valve
22
and bypass line
21
could be incorporated into high pressure pump
20
such that the high pressure pump would permit through flow when the pump is not working and the pressure differential corresponds to an equivalent of check valve
22
. Fuel will flow to the bypass line
21
from either the priming pump
16
or the fuel transfer pump
17
via the upstream portion of supply passage
13
a
. When fuel pressure flowing into the bypass line
21
from the upstream portion of the supply passage
13
a
is greater than the fuel pressure in the downstream portion of the supply passage
13
b
and the bias of the spring, the check valve
22
will open and fuel can flow into the downstream portion
13
b
. However, when the pressure within the downstream portion
13
b
is greater than pressure within the upstream portion
13
a
, the check valve
22
will remain closed. Both the priming pump
16
and the fuel transfer pump
17
can provide sufficient pressure within the bypass line
21
to open the valve
22
when the high pressure pump
20
has not yet begun producing output flow. It should be appreciated that the bypass line
21
could be connected to the downstream portion
13
b
in any conventional manner, including not limited to a junction box including a conventional T-connection and a safety valve.
The downstream portion
13
b
of the supply portion
13
is fluidly connected to the common rail
28
. The fuel within the common rail
28
is supplied to the plurality of fuel injectors
25
via accumulators
26
. Each fuel injector
25
preferably is in fluid communication with an accumulator
26
that isolates the injector
25
from pressure spikes. However, it should be appreciated that accumulators
26
are not necessary in the fuel system
10
. Although the present invention is illustrated as including six fuel injectors
25
and one common rail
28
, it should be appreciated that the fuel system could include more than one common rail and include any number of fuel injectors. The fuel injectors
25
inject fuel into the engine cylinders; fuel that is not injected is returned back to the fuel tank
12
via the return line
14
for re-circulation through the fuel system
10
. If needed, an air starter (not shown) is attached to the engine
11
to pump compressed air into the engine cylinders during the starting of the engine
11
. Those skilled will appreciate that electric start is also contemplated. It should be appreciated that an air check valve may be positioned within the common rail
28
, or at a high elevation point within the fuel system
9
, in order to evacuate any vapor and/or air bubbles from the fuel system. It should further be appreciated that the air and/or vapor could be pushed through a plurality of fuel injectors
25
and into the engine cylinder, or back to tank, during priming.
Preferably, the downstream portion
13
b
of the supply line
13
includes double walled lines. The pressurized fuel flows within a space defined by a first wall. If the pressurized fuel leaks through the first wall, the fuel can flow between the first wall and the second wall. The fuel that has remained within the first wall can travel to the fuel injectors
25
for injection into the engine cylinders. However, any fuel that has leaked in between the first and second walls will drain through a leakage line
45
. Positioned within the leakage line
45
is a wet sensor
38
that is preferably in communication with the electronic control module
24
via communication line
39
. If the wet sensor
38
senses moisture, the wet sensor
38
will communicate such to the electronic control module
24
, and the electronic control module
24
will alert the operator that there is a high pressure line leak. It should also be appreciated that, in order to sense leakage within the fuel system
9
, the wet sensor
38
could also be in fluid communication with other areas of high pressure within the fuel system
9
, such as the high pressure pump
20
. It should be appreciated that the present invention contemplates a fuel system without double walled high pressure lines and a wet sensor.
A control system
46
includes at least one sensor positioned with the fuel system
10
in order to sense the condition of the fuel system
10
. There can be a pressure sensor
30
positioned upstream from the high pressure pump
20
, another pressure sensor
31
positioned downstream from the high pressure pump
20
, an engine speed
32
sensor and an air starter condition sensor
33
in communication with the electronic control module
24
via the upstream communication line
34
, downstream communication line
35
, engine speed communication line
36
, and an air starter communication line
37
, respectively. Because the pressure sensor
31
is positioned downstream from the high pressure pump
20
, the pressure sensor
31
is sensing the pressure within a high pressure portion of the common rail
28
of the fuel system
10
. It should be appreciated that the sensor
31
can be attached to the common rail
28
. Because the pressure sensor
30
is positioned upstream from the high pressure pump
20
, the sensor
30
is sensing the pressure within the low pressure portion of the fuel system
10
. In the present invention's simplest version, the control system
46
only includes the upstream pressure sensor
30
. However, in a more sophisticated version of the present invention, the control system
46
can include fuel condition sensors in addition to the sensors
30
,
31
,
32
, and
33
in the illustrated example.
Referring to
FIG. 2
, there is shown a flow chart representing a priming algorithm
40
, according to the present invention. The electronic control module
24
includes a priming algorithm
40
being operable to activate the priming pump
16
when the fuel system
10
is in an unprimed state. For purposes of the present invention, the fuel system
10
is in an unprimed state when the fuel system pressure is below the threshold inlet pressure required for effective operation of the high pressure pump
20
. If the pressure is below the threshold inlet pressure, air and/or vapor bubbles could be trapped within the fuel system
10
. However, if the pressure is above the threshold inlet pressure, and thus, the fuel system
10
is in the primed state, generally, the fuel system
10
will also be free of air and/or vapor bubbles.
The priming algorithm
40
preferably includes an engine activation mode
40
a
and an inactive engine mode
40
b
, although it need not include the inactive engine mode
40
b
. When the priming algorithm
40
is in the engine activation mode
40
a
, the priming algorithm
40
a
is activated upon engine start-up initiation
11
a
. When the priming algorithm
40
is in the inactive engine mode
40
b
, the priming algorithm
40
b
is activated upon engine de-activation. Thus, the priming algorithm
40
will first determine whether engine start-up has been initiated. If engine start-up has been initiated, engine cranking
47
will preferably begin. However, it should be appreciated that the present invention contemplates systems in which the engine cranking is delayed until after the priming pump
16
has completed its operation.
While the engine
11
is cranking, the pressure sensor
30
will sense the pressure upstream from the high pressure pump
20
, and communicate such to the electronic control module
24
. The priming algorithm
40
a
determines whether the fuel system
10
is in the unprimed state, at least in part, by comparing the sensed upstream pressure
30
a
with a predetermined upstream pressure
30
b
. The present invention contemplates, in a more sophisticated version, other conditions, such as the downstream pressure, being sensed to determine whether the fuel system
10
is in the unprimed state. The predetermined upstream pressure
30
b
correlates to the threshold inlet pressure of the high pressure pump
20
. Those skilled in the art will appreciate that the predetermined upstream pressure
30
b
may vary depending on the size and type of high pressure pump
20
included within the fuel system
10
. If the sensed upstream pressure
30
a
is less the predetermined pressure
30
b
, the fuel system
10
has fallen to a pressure that is insufficient to effectively operate the high pressure pump
20
. Thus, the fuel system
10
is in the unprimed state, and the priming pump
16
will be activated
16
a
. If the sensed pressure
30
a
is greater than the predetermined pressure
30
b
, the fuel system
10
is a primed state, and the engine cranking time will be reasonable in order to start the engine
11
.
If the priming pump
16
has been activated, the priming algorithm
40
a
will continue to sense fuel system conditions in order to determine when the fuel system
10
reaches the primed state. The priming algorithm
40
a
will again compare the sensed upstream pressure
30
a
with the predetermined upstream pressure
30
b
. Further, the priming algorithm
40
a
will compare a sensed downstream pressure
31
a
with a predetermined downstream pressure
31
b
. The predetermined downstream pressure
31
b
can also be the threshold inlet pressure required for effective operation of the priming pump
16
. If at least one of the upstream pressure
30
a
and the downstream pressure
31
a
is greater than the predetermined upstream or downstream pressure
30
b
and
31
b
, respectively, the priming algorithm
40
a
will de-activate
16
b
the priming pump
16
. However, the priming algorithm
40
a
will also preferably sense the engine speed via the engine speed sensor
32
and the air starter condition via the air starter sensor
33
. The priming algorithm
40
a
will compare the sensed engine speed
32
a
and the sensed air starter condition
33
a
with the predetermined engine speed
32
b
and the predetermined air starter condition
33
b
, respectively. The predetermined engine speed
32
b
is the speed of the engine
11
that is sufficient to power the fuel transfer pump
17
to produce output at the threshold inlet pressure. The predetermined condition
33
b
of the air starter is activated. If the sensed engine speed
32
a
is greater than the predetermined engine speed
32
b
, the priming pump
16
will be de-activated
16
b
. Similarly, if the sensed air starter condition
33
a
is different than the predetermined air starter condition
33
b
, the priming pump
16
will be deactivated
16
b
. Thus, the fuel system
10
is in the primed state when at least one of the sensed upstream pressure
30
a
, the sensed downstream pressure
31
a
, and the sensed engine speed
32
a
is greater than the predetermined upstream pressure
30
b
, the predetermined downstream pressure
31
b
, and the predetermined engine speed
32
b
, respectively, or the sensed air starter condition
33
a
is different than the predetermined air starter condition
33
b.
If the sensed pressures
30
a
and
31
a
and the sensed engine speed
32
a
are less than the predetermined pressures
30
b
and
31
b
and the predetermined engine speed
32
b
, and the air starter condition
33
a
is different than the predetermined air starter condition
33
b
, the fuel system
10
is still in the unprimed state, and the priming pump
16
will remain active. The priming algorithm
40
a
will continue to compare the sensed fuel system conditions with the predetermined fuel system conditions until it determines that the fuel system
10
is in the primed state. It should be appreciated that in order to determine whether the fuel system
10
is in the primed state, the present invention contemplates sensing and comparing fuel system conditions in addition to, or other than, the above-listed conditions. Further, in a simpler version of the present invention, only one of the upstream pressure, downstream pressure, engine speed and air starter condition can be sensed to determine whether the fuel system is in the unprimed state.
When the priming algorithm
40
senses that the engine
11
has been de-activated, the inactive engine mode
40
b
of the priming algorithm
40
will begin monitoring the time the engine
11
remains inactive. After a predetermined time interval
44
when the engine is de-activated, the priming algorithm
40
is operable to determine whether the fuel system
10
is in the unprimed state. The length of predetermined time interval
44
can be a design choice, although the length is preferably not longer than required for the fuel system
10
to fall into the unprimed state.
The priming algorithm
40
b
will determine whether the fuel system
10
is in the primed condition by comparing the sensed upstream pressure
30
a
with the predetermined upstream pressure
30
b
. If the sensed pressures
30
a
is greater than the predetermined pressure
30
b
, the priming algorithm
40
b
will determine that the fuel system
10
is in the primed state, and the priming pump
16
will remain inactive. However, if the sensed pressure
30
a
is less than the predetermined pressure
30
b
, the priming algorithm
40
b
will activate
16
a
the priming pump
16
. It should be appreciated that the present invention contemplates additional fuel system conditions, such as the downstream pressure, being sensed and compared to determined whether the fuel system
10
is in the unprimed condition. The pressure sensor
30
will continue to sense the upstream pressures
30
a
, and communicate such to the electronic control module
24
. In addition, after the priming pump
16
is activated, the downstream pressure sensor
31
will also sense the downstream pressure
31
a
and compare it will the predetermined downstream pressure
31
b
. When at least one of the sensed pressures
30
a
and
31
a
exceeds the predetermined pressures
30
b
and
31
b
, the fuel system
10
is in the primed state, and the pump
16
will be de-activated
16
b
. Upon the next predetermined time interval
44
, the sensors
30
and
31
will again sense the pressures within the supply line
13
, and the process will repeat itself. Again, the fuel condition sensors could include additional condition sensors, or just one of the pressure sensors
30
a
or
30
b
. However, because the engine
11
remains inactive in the inactive engine mode
40
b
, the engine speed and the air starter condition will not be sensed to determine whether the fuel system
10
is in the primed state.
INDUSTRIAL APPLICABILITY
Referring to
FIGS. 1 and 2
, the present invention will be discussed for an internal combustion engine. Although the present invention is generally applicable to any internal combustion engine, the present invention finds specific application with relatively large engines, including but not limited to engines that are used in conjunction with electrical generators, locomotives, and marine applications.
When engine start-up is initiated, the engine cranking
47
will begin, and the engine activation mode
40
a
of the priming algorithm
40
will be activated. However, it should be appreciated that engine cranking can be delayed until after the operation of the priming pump
16
, if necessary, is completed. The upstream sensor
30
senses the pressure within the upstream portion
13
a
, and communicates such to the electronic control module
24
via the upstream sensor communication line
34
. The priming algorithm
40
will determine whether the fuel system
10
is in the unprimed state, at least in part, by comparing the sensed upstream pressure
30
a
with the predetermined upstream pressure
30
b
. The predetermined upstream pressure
30
b
corresponds to the threshold inlet pressure of the high pressure pump
20
. Because it is known in the art that if the sensed downstream pressure
31
a
has fallen below the threshold inlet pressure, then the upstream pressure
30
a
has more than likely also fallen below the threshold inlet pressure, the present invention contemplates both the upstream and downstream portions
13
a
and
13
b
of supply line
13
being sensed in order to provide reassurance as to the state of the fuel system
10
. In the illustrated example, if the sensed upstream pressure
30
a
is greater than the predetermined upstream pressure
30
b
, the fuel system
10
is in the primed state.
If the electronic control module
34
determines the fuel system
10
is in the primed state, the priming pump
16
will not be activated. Because the upstream pressure
30
a
is above the threshold inlet pressure of the high pressure pump
20
, the high pressure pump
20
can begin effective operation, thereby reducing the time required for the high pressure pump
20
to raise pressure to the outlet valve opening pressure and produce output. Once the high pressure pump
20
is producing output, the common rail
28
pressure can be raised to injection pressure levels, and the engine can start
48
.
However, if the sensed upstream pressure
30
a
is less than the predetermined upstream pressure
30
b
, the fuel system
10
is in the unprimed state. Although there are various reasons for the fuel system
10
being in the unprimed state, often the longer the engine
11
has been de-activated prior to engine start-up and the colder the temperature of the fuel system, the more likely the fuel system
10
will go into an unprimed state. When the fuel system
10
is in the unprimed state, the priming algorithm
40
preferably will activate the priming pump
16
via the pump communication line
23
. However, it should be appreciated that if the fuel system
10
included only two fuel pumps, the priming algorithm
40
would activate an electrically powered fuel transfer pump.
The priming pump
16
will begin pumping fuel from the fuel tank
12
and through the first fuel filter
15
and the second fuel filter
19
. In the illustrated example, engine cranking
47
is occurring simultaneously with the operation of the priming pump
16
. However, while simultaneously operating the priming pump
16
and cranking the engine
11
may provide increased fuel flow to the fuel system
10
caused by both the priming pump
16
and the fuel transfer pump
17
output, it also requires significant amount of energy to power both the engine cranking
47
and the priming pump
16
simultaneously. A portion of the fuel will flow through the bypass line
21
around the high pressure pump
20
, and another portion will flow through the upstream portion
13
a
of the supply line
13
to the high pressure pump
20
. The high pressure pump
20
may not yet be sufficiently powered to create the outlet valve opening pressure in order to produce output. Thus, the fuel flowing through the bypass line
21
will be sufficient to open the check valve
22
against the pressure within the downstream portion
13
b
, and the priming pump
16
will be priming the common rail
28
with fuel by supplying fuel to the common rail
28
. Thus, the priming pump
16
can supply fuel to the common rail
28
in order to evacuate vapor and/or air bubbles while also raising the pressure of the fuel system
10
to the threshold inlet pressure required for effective operation of the high pressure pump
20
. In addition to an alternative to bypassing fuel around the high pressure pump
20
via the bypass line
25
, the valve opening pressure of the pump outlet valve can be lowered such that the pressure created by the priming pump
16
and/or the fuel transfer pump
17
is sufficient to open the pump outlet valve. Thus, the priming pump
16
could supply fuel to the common rail
28
via the high pressure pump
20
before the high pressure pump
20
begins operating. Those skilled in the art will appreciate that the bypass line
25
and the lowered pump outlet valve opening pressure can be used in conjunction with one another or separately. If used together, fuel could simultaneously flow through the bypass line
21
and the high pressure pump
20
. When the high pressure pump
20
begins producing output exceeding the predetermined downstream pressure
31
a
, the check valve
22
will close.
The upstream pressure sensor
30
, the downstream pressure sensor
31
, the engine speed sensor
32
and the air starter condition sensor
33
will sense their respective conditions. When at least one of the sensed upstream pressure
30
a
, the sensed downstream pressure
31
a
, and the sensed engine speed
32
a
is greater than the predetermined upstream pressure
30
b
, predetermined downstream pressure
31
b
, and the predetermined engine speed
32
b
, respectively, or the sensed air starter condition
33
a
is different than the predetermined air starter condition
33
b
, the electronic control module
24
will determine that the fuel system
10
is in the primed state. Thus, the fuel pressure within the upstream portion
13
a
of the supply line
13
is above the threshold inlet pressure of the high pressure pump
20
. The priming algorithm
40
will de-activate
16
b
the priming pump
16
.
Because the pressure within the upstream portion
13
a
is above the threshold inlet pressure, the high pressure pump can relatively quickly raise the pressure within the high pressure pump
20
. Once the pressure reaches the outlet valve opening pressure, the outlet valve will open, and the high pressure pump
20
will supply pressurized fuel to the common rail
28
. Because the common rail
28
is already above the threshold inlet pressure, any vapor and/or air bubbles trapped within the common rail
28
may be already evacuated, thereby reducing the time for the high pressure pump
20
to raise the common rail
28
to injection pressure. Once at injection pressure, the engine can start
48
. Thus, because the common rail
28
can be filled with fuel while the fuel system
10
is being raised to the threshold inlet pressure, the engine cranking time is reduced.
Preferably, the priming algorithm
40
also includes the inactive engine mode
40
b
. The inactive engine mode
40
b
is activated when the engine
11
is de-activated. When the engine
11
is de-activated, the priming algorithm
40
will begin monitoring the time the engine
11
has remained inactive. Upon the predetermined time interval
44
, that is the time in which the pressure within the fuel system
10
could fall into the unprimed state, the pressure sensor
30
will sense the upstream pressure
30
a
, and communicate such to the electronic control module
24
via the communication line
34
. The priming algorithm
40
will compare the sensed pressure
30
a
with the predetermined upstream pressure
30
b
. If the sensed pressure
30
a
is greater than the predetermined pressure
30
b
, the fuel system
10
is in the primed state, and the priming algorithm
40
will not activate the priming pump
16
. Thus, the fuel system
10
could start the engine
111
without first raising the fuel system pressure to threshold inlet valve pressure and filling the common rail
28
will fuel. The priming algorithm
40
will again compare the sensed pressure
30
a
to the predetermined pressure
30
b
after another predetermined time interval
44
. It should be appreciated that the predetermined time interval
44
between the comparisons could shorten as the time the engine
11
remains inactive increases. Further, it should be appreciated that the present invention contemplates priming algorithm
40
could adjust the length of the predetermined time interval based on sensed ambient temperature. The longer the engine
11
remains inactive and the colder the ambient temperature, the greater the possibility that the fuel system
10
is in the unprimed state.
However, if the sensed pressure
30
a
is less than the predetermined pressure
30
b
, the priming algorithm
40
will activate the priming pump
16
which will draw fuel from the fuel tank
12
and deliver the same to the bypass line
21
. The fuel within the bypass line
21
can open the valve
22
and flow to the common rail
28
via the downstream portion
13
b
. The fuel will be delivered to the common rail
28
in order to begin priming the common rail
28
. Thus, when the engine
11
is activated
11
a
, the fuel system
10
will be in the primed condition. After the priming pump
16
is activated, the priming algorithm
40
will continue to compare the sensed pressures
30
a
and
31
a
to the predetermined pressures
30
b
and
31
b
, respectively. When at least one of the sensed pressures
30
a
and
31
a
is greater than the predetermined pressures
30
b
and
31
b
, the priming algorithm
40
will de-activate the priming pump
16
. The priming algorithm
40
will again sense the upstream pressure
30
a
and compare it with the predetermined upstream pressure
30
b
upon the next predetermined time interval
44
. The process will continue to repeat until the engine start-up is initiated.
The present invention is advantageous because it reduces engine cranking time by sensing when the fuel system
10
is in the unprimed state and decreasing the time it takes the fuel system
10
to reach the primed state by activating an electrically powered priming pump
16
. In the preferred embodiment of the present invention, either prior to or simultaneously to engine cranking, the priming pump
16
can raise the pressure of the fuel system
10
to threshold inlet pressure and supply fuel to the common rail
28
in unprimed situations when the high pressure pump
20
is not yet producing output. Thus, effective operation of the high pressure pump
20
is not delayed by the fuel transfer pump
17
, and filling the common rail
28
with fuel is not delay by the high pressure pump
20
. Engine start-up time can, thus, be reduced while utilizing the mechanically-powered fuel transfer pump
17
.
Moreover, mechanically-powered pumps, such as the fuel transfer pump
17
and the high pressure pump
20
, are generally considered more efficient and more reliable than electrically powered pumps for larger engines. Mechanically-powered pumps are more efficient because they utilize energy already created directly by the engine
11
. Specifically, in relatively large engines, such as those used in conjunction with generators, boats, and locomotives, the fuel transfer pump
17
must be relatively powerful to circulate fuel through the large fuel system. Thus, an electrically powered fuel transfer pump used in these engines could be especially inefficient and costly.
In addition, the present invention is advantageous because the method of priming around the fuel transfer pump
20
is electronically controlled. Thus, the state of the fuel system
10
can be monitored even when the engine
11
is inactive to assure that the engine
11
can start without unreasonable delay. In addition to delay in engine cranking times being an annoyance, unreasonably long engine cranking times can be detrimental in emergencies. For instance, an engine used with a generator may remain inactive for a long period of time. However, if the primary power source fails, the generator may have a limited to time to restore power without detrimentally affecting those whom the power is serving. The present invention can assure that the fuel system is primed for such an emergency.
It should be understood that the above description is intended for illustrative purposes only, and is not intended to limit the scope of the present invention in any way. Thus, those skilled in the art will appreciate that other aspects, objects, and advantages of the invention can be obtained from a study of the drawings, the disclosure and the appended claims.
Claims
- 1. A fuel system comprising:a first fuel pump being electrically powered and in communication with an electronic control module; a second fuel pump being operably coupled to an engine; and the electronic control module including a priming algorithm being operable to activate the first fuel pump when the fuel system is in an unprimed state, and the priming algorithm including an inactive engine mode.
- 2. The fuel system of claim 1 wherein the priming algorithm includes an engine activation mode and the inactive engine mode.
- 3. The fuel system of claim 1 including a common rail being fluidly connectable to at least one fuel injector; andthe first fuel pump being in fluid communication with the common rail via a bypass line, which is free of any pump, when the fuel system is in the unprimed state.
- 4. The fuel system of claim 1 including at least one fuel system condition sensor being in communication with the electronic control module.
- 5. The fuel system of claim 4 wherein the at least one fuel system condition sensor including a pressure sensor upstream from the second fuel pump.
- 6. The fuel system of claim 1 including a third pump being positioned upstream from the second pump and being operably coupled to the engine.
- 7. The fuel system of claim 6 wherein the priming algorithm being operable to de-activate the first fuel pump when the fuel system is in a primed state.
- 8. The fuel system of claim 7 wherein the first fuel pump being a priming pump, the second fuel pump being a high pressure pump, and the third fuel pump being a fuel transfer pump;the priming pump being in fluid communication with a common rail via at least one of a bypass line around the high pressure pump and through the high pressure pump when the fuel system is in the unprimed state, and the fuel transfer pump being in fluid communication with the common rail via the high pressure pump when the fuel system is in a primed state; the priming algorithm including an engine activation mode and the inactive engine mode; and the electronic control module being in communication with a pressure sensor upstream from the high pressure pump.
- 9. A control system, comprising:at least one sensor operable to sense a state of the fuel system of an engine; an electronic control module being in communication with the at least one sensor and including a priming algorithm; and the priming algorithm being operable to activate an electrically powered fuel pump when the state of the fuel system is unprimed, the engine is inactive and the priming algorithm is in an inactive engine mode.
- 10. The control system of claim 9 wherein the priming algorithm being operable to de-activate the electrically powered fuel pump when the fuel system is in a primed state.
- 11. The control system of claim 10 wherein the at least one sensor includes a pressure sensor upstream from a high pressure pump.
- 12. The control system of claim 11 wherein the priming algorithm includes a comparing algorithm being operable to compare a sensed upstream pressure with a predetermined upstream pressure.
- 13. The control system of claim 12 wherein the priming algorithm includes an engine activation mode and the inactive engine mode.
- 14. A method of priming a fuel system of an engine, comprising the steps of:determining whether the engine is activated; determining whether the fuel system is in an unprimed state; and if the fuel system is in the unprimed state, and the engine is inactive, then activating an electrically powered fuel pump via an electronic control module.
- 15. The method of claim 14 including a step of circulating fuel, at least in part, by bypassing a second pump operably coupled to an engine when the fuel system is in an unprimed state.
- 16. The method of claim 15 wherein the step of determining includes a step of sensing a pressure upstream from the second pump.
- 17. The method of claim 16 wherein the step of determining includes a step of comparing the sensed upstream pressure with a predetermined upstream pressure.
- 18. The method of claim 14 including a step of, if the fuel system is in a primed state, de-activating the electrically powered fuel pump.
- 19. The method of claim 18 including a step of determining whether the fuel system is in the primed state, at least in part, by sensing at least one of pressure upstream from the high pressure pump, pressure downstream from the high pressure pump, engine speed and air starter condition.
- 20. The method of claim 18 including a step of operably coupling a third pump to an engine.
US Referenced Citations (15)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0 643 219 |
Mar 1995 |
EP |
0 643 219 |
Jan 1998 |
EP |