U.S. patent application number 13/983839 was filed with the patent office on 2013-11-28 for exhaust purification system for working machine.
This patent application is currently assigned to HITACHI CONSTRUCTION MACHINERY CO., LTD.. The applicant listed for this patent is Kouta Fujieda, Yuuki Gotou, Akira Kimura, Keiichiro Nakamura, Kazuhiro Shibamori, Hidenobu Tsukada, Yutaka Watanabe. Invention is credited to Kouta Fujieda, Yuuki Gotou, Akira Kimura, Keiichiro Nakamura, Kazuhiro Shibamori, Hidenobu Tsukada, Yutaka Watanabe.
Application Number | 20130312616 13/983839 |
Document ID | / |
Family ID | 47009144 |
Filed Date | 2013-11-28 |
United States Patent
Application |
20130312616 |
Kind Code |
A1 |
Shibamori; Kazuhiro ; et
al. |
November 28, 2013 |
EXHAUST PURIFICATION SYSTEM FOR WORKING MACHINE
Abstract
An exhaust purification system for a working machine reliably
issues filter regeneration warnings to the operator, prompting
manual regeneration, so that damage to the DPF device can be
avoided. When a PM estimate becomes higher than a given value, a
screen displays a warning message prompting manual regeneration. If
the warning message fails to prompt the operator to perform manual
regeneration and reference time t1 has passed since the display of
the warning message, a speaker outputs a first warning sound. When
the operator notices the first warning sound and turns on a
regeneration switch, regeneration control is started. If the
operator fails to notice the first warning sound and reference time
t2 passes, the speaker instead outputs a second warning sound
louder than the first warning sound. When the operator notices the
second warning sound and turns on the regeneration switch,
regeneration control is started.
Inventors: |
Shibamori; Kazuhiro;
(Joso-shi, JP) ; Watanabe; Yutaka; (Tsuchiura-shi,
JP) ; Tsukada; Hidenobu; (Ushiku-shi, JP) ;
Nakamura; Keiichiro; (Mito-shi, JP) ; Kimura;
Akira; (Ryuugasaki-shi, JP) ; Gotou; Yuuki;
(Tsuchiura-shi, JP) ; Fujieda; Kouta; (Hokota-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shibamori; Kazuhiro
Watanabe; Yutaka
Tsukada; Hidenobu
Nakamura; Keiichiro
Kimura; Akira
Gotou; Yuuki
Fujieda; Kouta |
Joso-shi
Tsuchiura-shi
Ushiku-shi
Mito-shi
Ryuugasaki-shi
Tsuchiura-shi
Hokota-shi |
|
JP
JP
JP
JP
JP
JP
JP |
|
|
Assignee: |
HITACHI CONSTRUCTION MACHINERY CO.,
LTD.
Tokyo
JP
|
Family ID: |
47009144 |
Appl. No.: |
13/983839 |
Filed: |
February 27, 2012 |
PCT Filed: |
February 27, 2012 |
PCT NO: |
PCT/JP2012/054820 |
371 Date: |
August 6, 2013 |
Current U.S.
Class: |
96/419 |
Current CPC
Class: |
E02F 9/2282 20130101;
Y02T 10/47 20130101; F01N 2590/08 20130101; E02F 9/2285 20130101;
F02D 2041/228 20130101; E02F 9/2296 20130101; F01N 3/035 20130101;
F01N 11/00 20130101; F02D 2200/0812 20130101; F01N 3/0253 20130101;
E02F 9/2066 20130101; F01N 3/023 20130101; E02F 9/2095 20130101;
F02D 41/029 20130101; F02D 2200/604 20130101; Y02T 10/40 20130101;
F01N 2550/04 20130101; E02F 9/267 20130101 |
Class at
Publication: |
96/419 |
International
Class: |
F01N 3/023 20060101
F01N003/023 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 15, 2011 |
JP |
2011-091571 |
Claims
1. (canceled)
2. (canceled)
3. An exhaust purification system for working machine, the system
comprising: a filler (32), located in an exhaust system of an
engine (1), for capturing particulate matter contained in exhaust;
a regeneration device (33, 39) for burning off particulate matter
accumulated on the filter to regenerate the filler; a regeneration
controller (42) for starting or stopping the operation of the
regeneration device; a regeneration switch (38) for instructing the
regeneration controller to start regeneration; and warning means
(6a, 42a, 43) for prompting an operator to turn on the regeneration
switch, wherein the system further comprises status judging means
(3, 8, 41a, 47) for judging the status of the working machine,
wherein the warning means includes a warning sound output function
(6c) for outputting warning sounds and a warning sound altering
function (41b) for altering the warning sounds after the amount of
time during which the status judging means judges the working
machine to be in operation has exceeded reference times since a
first warning, wherein in the event that the status judging means
judges the working machine to be in operation, the status judging
means further judges whether the working machine is in standby
status or work-in-progress status, and wherein the warning sound
altering function sets different reference times depending on the
standby status or the work-in-progress status.
4. The exhaust purification system of claim 3 wherein the working
machine comprises: an engine speed detector (3); a work-performing
structure; operating levers (28, 29) for controlling the operation
of the work-performing structure; a gate lock lever (7) movable
between an unlock position that enables the operation of the
operating levers and a lock position that disables the operation of
the operating levers; and a pilot pressure sensor (47) for
detecting pilot pressures generated by the operating levers,
wherein the status judging means judges the working machine to be
in the standby status in the event that the engine speed detector
has detected a speed higher than a low idle speed and that the gate
lock lever is in the lock position, and wherein the status judging
means judges the working machine to be in the work-in-progress
status in the event that the engine speed detector has detected a
speed higher than the low idle speed, that the gate lock lever is
in the unlock position, and that the pilot pressure sensor has
detected a pressure higher than a given value.
5. The exhaust purification system of claim 3 wherein the warning
sound altering function alters at least either one of the
following: the volume, tone, length, and repeat count of the
warning sounds.
6. (canceled)
Description
TECHNICAL FIELD
[0001] The present invention relates to exhaust purification
systems for working machine and particularly to an exhaust
purification system that uses a filter to capture the particulate
matter contained in exhaust for purifying the exhaust and prompts
the operator to start manual filter regeneration so that the
particulate matter captured by the filter can be burnt off and
removed.
BACKGROUND ART
[0002] Working machine (e.g., hydraulic excavators) has a diesel
engine as its power source. The particulate matter (PM) discharged
from the diesel engine and other hazardous substances such as NOx,
CO, and HC are subject to severer emission regulations year by
year. Such being the case, there exists an exhaust purification
system that uses a diesel particulate filter (DPF) to capture
particulate matter, thereby reducing PM emission. Such a system
burns the particulate matter captured by the filter to prevent its
clogging, thereby regenerating the filter. Otherwise, an increase
in the PM accumulated on the filter may clog the filter, which
increases the exhaust temperature of the engine and deteriorates
fuel efficiency.
[0003] Filter regeneration is often performed with the use of an
oxidation catalyst. The catalyst is positioned upstream of the
filter or directly supported by the filter or both. In either case,
activating the catalyst requires exhaust temperature to be higher
than the activation temperature of the catalyst. When exhaust
temperature is sufficiently high, the filter self-regenerates, but
there are also cases where exhaust temperature is too low for
self-regeneration and where self-regeneration is not enough for
burning particulate matter. In such cases, compulsory regeneration
is employed to raise exhaust temperature above the activation
temperature of the catalyst. Methods of compulsory regeneration
include one in which fuel injection is performed during the
expansion stroke after main fuel injection into the engine
cylinder; one in which fuel is injected into the exhaust gas within
the exhaust pipe with the use of a fuel injector disposed within
the exhaust pipe; one in which the engine load is increased by
raising the engine speed; and one in which the engine load is
increased by utilizing the hydraulic load effect.
[0004] Compulsory filter regeneration also includes automatic
regeneration in which regeneration is started automatically and
manual regeneration in which regeneration is started by the
operator. Automatic regeneration is performed when an estimated
amount of accumulated PM reaches a threshold or when a given amount
of time has passed. If automatic regeneration is not performed
properly, the accumulation of particulate matter may proceed.
[0005] Patent Document 1 discloses a technique related to manual
regeneration in which a warning is issued to the operator (e.g.,
via a warning lamp) to prompt manual regeneration. When the
operator turns on the regeneration switch, regeneration is
started.
[0006] During the excavation work by a hydraulic excavator, the
operator may fail to notice a warning prompting manual regeneration
if he is too focused on the work. Moreover, if he places high
priority on the completion of the work, he may ignore the manual
regeneration warning. If manual regeneration is not performed after
the warning, the accumulation of PM will proceed. Eventually, the
in-filter temperature may increase excessively due to the
combustion of a large amount of PM, damaging the DPF device.
[0007] In the technique of Patent Document 1, the form of a warning
is changed based on an estimated amount of accumulated PM. At
first, a warning lamp flashes slowly, but when the DPF device is
more likely to be damaged due to an increased amount of PM, the
warning lamp starts to flash quickly. While the technique of Patent
Document 1 is related to automobiles in general, it is also
applicable to working machine such as hydraulic excavators. With
the technique of Patent Document 1, the operator can recognize the
urgency of the necessity of manual regeneration by noticing warning
changes. By the operator then performing manual regeneration
properly, damage to the DPF device can be avoided.
PRIOR ART LITERATURE
Patent Document
[0008] Patent Document 1: JP,A 2005-299403
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0009] In filter regeneration, whether automatic or manual, the
amount of accumulated PM is often estimated by detecting the
differential pressure across the filter and then performing
calculations based on the differential pressure. Thus, the accuracy
of control based on an estimated amount of accumulated PM depends
on the accuracy of that PM estimate. In other words, when the PM
estimate has errors, warnings cannot be changed properly. When a PM
estimate is higher than the actual PM amount and warnings are
changed based on that estimate, the error causes no problems.
However, when a PM estimate is lower than the actual PM amount and
warnings are changed based on that estimate, judgment associated
with the alteration of the warnings may be delayed. This delay
could be an indirect cause of DPF breakage because manual
regeneration cannot be performed properly (i.e., the start of the
manual regeneration is delayed).
[0010] An object of the present invention is to provide an exhaust
purification system for working machine that reliably issues filter
regeneration warnings to the operator, prompting manual
regeneration, so that damage to the DPF device can be avoided.
Means for Solving the Problem
[0011] (1) To achieve the above object, the present invention
provides an exhaust purification system for working machine, the
system comprising: a filter, located in an exhaust system of an
engine, for capturing particulate matter contained in exhaust; a
regeneration device for burning off particulate matter accumulated
on the filter to regenerate the filter; a regeneration controller
for starting or stopping the operation of the regeneration device;
a regeneration switch for instructing the regeneration controller
to start regeneration; and warning means for prompting an operator
to turn on the regeneration switch. The system further comprises
status judging means for judging the status of the working machine,
and the warning means includes a warning altering function for
altering the content of warnings based on the amount of time during
which the status judging means judges the working machine to be in
operation since a first warning.
[0012] (2) To achieve the above object, the invention also provides
an exhaust purification system for working machine, the system
comprising: a filter, located in an exhaust system of an engine,
for capturing particulate matter contained in exhaust; a
regeneration device for burning off particulate matter accumulated
on the filter to regenerate the filter; a regeneration controller
for starting or stopping the operation of the regeneration device;
a regeneration switch for instructing the regeneration controller
to start regeneration; and warning means for prompting an operator
to turn on the regeneration switch. The system further comprises
status judging means for judging the status of the working machine,
and the warning means includes a warning sound output function for
outputting warning sounds and a warning sound altering function for
altering the warning sounds when the amount of time during which
the status judging means judges the working machine to be in
operation exceeded reference times after a first warning.
[0013] In conventional techniques, the content of a warning is
changed based on an estimated amount of accumulated PM. Thus, if
the estimate has errors, the warning may not be changed properly.
In contrast, changing warning sounds based on elapsed time as above
allows the warning sounds to be changed more reliably without being
affected by PM estimation errors, and by the operator noticing the
warning sounds and performing manual regeneration, damage to the
DPF device can be avoided.
[0014] (3) In the above system of (2), in the event that the status
judging means judges the working machine to be in operation, the
status judging means further judges whether the working machine is
in standby status or work-in-progress status and wherein the
warning sound altering function sets different reference times
depending on the standby status or the work-in-progress status.
[0015] During standby status, more particulate matter may be
accumulated than during work-in-progress status. Thus, during
standby status, changing warning sounds based on the reference
times for work-in-progress status may delay judgment associated
with the alteration of the warning sounds. Therefore, during
standby status, warning sounds are changed based on the reference
times for standby status, thereby preventing the judgment from
being delayed and ensuring a reliable alternation of warning
sounds.
[0016] (4) In the above system of (3), the working machine
comprises: an engine speed detector; a work-performing structure;
operating levers for controlling the operation of the
work-performing structure; a gate lock lever movable between an
unlock position that enables the operation of the operating levers
and a lock position that disables the operation of the operating
levers; and a pilot pressure sensor for detecting pilot pressures
generated by the operating levers. The status judging means judges
the working machine to be in the standby status in the event that
the engine speed detector has detected a speed higher than a low
idle speed and that the gate lock lever is in the lock position. On
the other hand, the status judging means judges the working machine
to be in the work-in-progress status in the event that the engine
speed detector has detected a speed higher than the low idle speed,
that the gate lock lever is in the unlock position, and that the
pilot pressure sensor has detected a pressure higher than a given
value.
[0017] The above allows the warning sound altering function to
change warning sounds based on the reference times for
work-in-progress status during work-in-progress status and based on
the reference times for standby status during standby status.
[0018] (5) In the above system of (2), the warning sound altering
function alters at least either one of the following: the volume,
tone, length, and repeat count of the warning sounds.
[0019] With such alteration of the warning sounds, it becomes more
likely for the operator to notice the sounds.
[0020] (6) To achieve the above object, the invention further
provides an exhaust purification system for working machine, the
system comprising: a filter, located in an exhaust system of an
engine, for capturing particulate matter contained in exhaust; PM
estimating means for estimating the amount of particulate matter
accumulated on the filter; a regeneration device for burning off
the particulate matter accumulated on the filter to regenerate the
filter; a regeneration controller for starting or stopping the
operation of the regeneration device; a regeneration switch for
instructing the regeneration controller to start regeneration; and
warning means for prompting an operator to turn on the regeneration
switch. The warning means includes a warning sound output function
for outputting warning sounds and a warning sound altering function
for altering the warning sounds based on the PM amount estimated by
the PM estimating means.
EFFECT OF THE INVENTION
[0021] In accordance with the invention, filter regeneration
warnings can be issued to the operator in a more reliable manner,
and with proper manual regeneration, damage to the DPF device can
be avoided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 illustrates the overall configuration of an exhaust
purification system according to Embodiment 1;
[0023] FIG. 2 illustrates the hydraulic circuit employed in a
hydraulic excavator;
[0024] FIG. 3 is an external view of the hydraulic excavator;
[0025] FIG. 4 illustrates the functional blocks of a
controller;
[0026] FIG. 5 is a flowchart illustrating the calculations
performed by the controller;
[0027] FIG. 6 illustrates a problem associated with Embodiment 1;
and
[0028] FIG. 7 illustrates an advantage of Embodiment 2.
MODE FOR CARRYING OUT THE INVENTION
Embodiment 1
[0029] Embodiment 1 of the present invention will now be described
with reference to the accompanying drawings.
Configuration
[0030] FIG. 1 illustrates the overall configuration of an exhaust
purification system for working machine according to Embodiment
1.
[0031] The working machine of FIG. 1 (a hydraulic excavator being
shown as an example) has a diesel engine 1 installed. The diesel
engine 1 includes an electronic governor 1a, an electronic device
for controlling fuel injection. A target speed of the engine 1 is
set by an engine control dial 2, and the actual speed of the engine
1 is detected by a speed detector 3. A controller 4 receives a
command signal from the engine control dial 2 and a speed signal
from the speed detector 3 and controls the electronic governor la
based on the command signal (indicative of the target speed) and
the speed signal (indicative of the actual speed), thereby
controlling the speed and torque of the engine 1.
[0032] A key switch 5 is used to start or stop the engine 1. The
controller 4 also receives a command signal from the key switch 5
and controls the start and stop of the engine 1 based on that
signal. The key switch 5 also acts as a device for starting or
stopping power supply for the controller 4 and a display device
6.
[0033] Operating levers 28 and 29 (see FIG. 2) and a gate lock
lever 7 are installed within the cab 107 of the hydraulic
excavator. The gate lock lever 7 can be moved between position A
(unlock position) that closes the entrance to a cab seat 108 and
position B (lock position) that opens the entrance to the cab seat
108. The gate lock lever 7 includes a position detector 8 for
detecting the position of the lever 7.
[0034] The exhaust purification system is installed on the exhaust
pipe 31 of the engine 1. The system includes the following
components: a DPF device 34 including a filter 32 for capturing the
particulate matter contained in exhaust and an oxidation catalyst
33 located upstream of the filter 32; a differential pressure
detector 36 for detecting the differential pressure across the
filter 32 (i.e., pressure loss across the filter 32); an exhaust
temperature detector 37, located upstream of the filter 32, for
detecting exhaust temperature; a regeneration switch 38 for
starting filter regeneration; and a fuel injector 39, located
within the exhaust pipe 31 (i.e., between the engine 1 and the DPF
device 34), for increasing the exhaust temperature. The oxidation
catalyst 33 and the fuel injector 39 constitute a filter
regeneration device that burns off the particulate matter
accumulated on the filter 32.
[0035] The regeneration switch 38 is located at an easily
accessible position within the cab 107 of the hydraulic excavator.
The operator uses the regeneration switch 38 to start the
regeneration of the filter 32. When turned on, the regeneration
switch 38 outputs a command signal that starts the regeneration of
the filter 32. The regeneration switch 38 may instead be an icon
displayed on the display device 6. In either case, the regeneration
switch is operated for the operator to turn it on or off.
[0036] The display device 6 is located at an easily viewable
position within the cab 107 of the hydraulic excavator and designed
to show basic vehicle information such as remaining fuel, coolant
temperature, and so on. The display device 6 includes a screen 6a,
control switches 6b, and a speaker 6c, and its operation is
controlled by the display controller 43 (see FIG. 4) of the
controller 4. The control switches 6b are located below the screen
6a. By the operator operating the switches 6b, the screen 6a can
display information other than the basic vehicle information. The
screen 6a and the control switches 6b serve as an interface,
allowing the operator to operate the switches 6b while viewing the
screen 6a for changing various vehicle-related settings.
[0037] The display device 6 also displays regeneration-related
information such as the status of automatic regeneration, a warning
prompting the operation of the regeneration switch 38, and so
forth. The speaker 6c can output such information in the form of
voice.
[0038] In the present embodiment, the speaker 6c outputs warning
sounds when manual regeneration is not being done properly
(described later in detail).
[0039] FIG. 2 illustrates the hydraulic circuit employed in the
construction machine (e.g., hydraulic excavator). The hydraulic
circuit includes the following components: a variable-displacement
hydraulic pump 11 (i.e., main pump) and a fixed-displacement pilot
pump 12 both driven by the engine 1; a hydraulic motor 13 and
hydraulic cylinders 14 and 15 (i.e., hydraulic actuators) driven by
the hydraulic fluid discharged from the hydraulic pump 11; pilot
flow-rate control valves 17 to 19 for controlling the flow (i.e.,
flow rate and direction) of the hydraulic fluid fed from the
hydraulic pump 11 to the hydraulic motor 13 and the hydraulic
cylinders 14 and 15; a pilot relief valve 21 for maintaining the
pressure of the hydraulic fluid discharged from the pilot pump 12
at a constant value (the pilot relief valve 21 constituting a pilot
hydraulic pressure source 20); a main relief valve 22 for
determining an upper limit to the discharge pressure of the
hydraulic pump 11; a solenoid valve 23 connected to the downstream
side of the pilot hydraulic pressure source 20 and turned on or off
depending on the position of the gate lock lever 7 located at the
entrance to the cab seat; and remote control valves 25, 26, and 27,
connected to a pilot hydraulic line 24 located downstream of the
solenoid valve 23, for generating, based on the hydraulic pressure
of the pilot hydraulic pressure source 20, control pilot pressures
a to f to control the flow-rate control valves 17 to 19.
[0040] The hydraulic pump 11 includes a regulator 11a for
controlling the tilt of the hydraulic pump 11 (i.e., the tilt of
the swash plate, hence the displacement volume of the pump 11)
based on the discharge pressure of the pump 11 so that the
absorption torque (consumption torque) of the pump 11 will not
exceed a given maximum absorption torque.
[0041] The remote control valves 25, 26, and 27 are controlled by
the operating levers 28 and 29 installed at the right and left
sides of the cab seat 108 (see FIG. 1). The operating levers 28 and
29 can be moved crosswise. Moving the operating lever 28 in the
directions of one line of a cross operates the remote control valve
25 while moving the operating lever 28 in the directions of the
other line of the cross operates the remote control valve 27.
Likewise, moving the operating lever 29 in the directions of one
line of a cross operates the remote control valve 26 while moving
the operating lever 29 in the directions of the other line of the
cross operates another remote control valve not illustrated. When
the operating lever 28 is moved in the two directions of one line
of a cross, moving the lever 28 in one of the two directions from
its neutral position causes the remote control valve 25 to generate
the control pilot pressure a while moving the lever 28 in the other
direction causes the remote control valve 25 to generate the
control pilot pressure b. The control pilot pressures a and b are
directed to the associated pressure receivers of the flow-rate
control valve 17 through pilot lines 25a and 26b, thereby moving
the flow-rate control valve 17 from its neutral position.
[0042] Similarly, when the operating lever 28 is moved in the two
directions of the other line of the cross, moving the lever 28 in
one of the two directions from the neutral position causes the
remote control valve 27 to generate the control pilot pressure e
while moving the lever 28 in the other direction causes the remote
control valve 27 to generate the control pilot pressure f. The
control pilot pressures e and f are directed to the associated
pressure receivers of the flow-rate control valve 19 through pilot
lines 27a and 27b, thereby moving the flow-rate control valve 19
from its neutral position. Likewise, when the operating lever 29 is
moved in the two directions of one line of a cross, moving the
lever 29 in one of the two directions from its neutral position
generates the control pilot pressure c while moving the lever 29 in
the other direction generates the control pilot pressure d. The
control pilot pressures c and d are directed to the associated
pressure receivers of the flow-rate control valve 18 through pilot
lines 26a and 26b, thereby moving the flow-rate control valve 18
from its neutral position.
[0043] The hydraulic circuit further includes shuttle valves 46 and
a pressure sensor 47. The shuttle valves 46 are designed to extract
the highest pressure among the control pilot pressures a to f of
the remote control valves 26 to 27 and the control pilot pressures
of other operating units. The pressure sensor 47 is connected to
the output port of the shuttle valve 46 located furthest downstream
and used to detect the highest control pilot pressure to detect the
operation of an operating lever or unit.
[0044] The control pilot pressures a to f are allowed to flow or
blocked depending on the position of the gate lock lever 7.
[0045] When the gate lock lever 7 is placed in position A (see FIG.
1), the solenoid of the solenoid valve 23 is excited, shifting the
solenoid valve 23 from the position of FIG. 2 and directing the
hydraulic pressure of the pilot hydraulic pressure source 20 to the
remote control valves 25, 26, and 27. This allows the remote
control valves 25, 26, and 27 to control the flow-rate control
valves 17 to 19. When the gate lock lever 7 is raised to position B
(see FIG. 1), the solenoid of the solenoid valve 23 becomes
inactive, shifting the solenoid valve 23 to the position of FIG. 2
and disconnecting the pilot hydraulic pressure source 20 from the
remote control valves 25, 26, and 27. This prevents the remote
control valves 25, 26, and 27 from controlling the flow-rate
control valves 17 to 19. In other words, when the gate lock lever 7
is in position B, the remote control valves 25, 26, and 27 (control
lever units) are locked, and lowering the gate lock lever 7 to
position A unlocks the valves 25, 26, and 27. Shifting the position
of the solenoid valve 23 by the gate lock lever 7 can be achieved
by, for example, installing a switch between the solenoid of the
solenoid valve 23 and its power source. When the gate lock lever 7
is in position A, that switch is turned on (closed state) to excite
the solenoid. When the gate lock lever 7 is in position B, the
switch is turn off (open state) to make the solenoid inactive.
[0046] FIG. 3 is an external view of the hydraulic excavator. The
excavator includes a lower carrier structure 100, an upper swing
structure 101, and a front shovel structure 102. The lower carrier
structure 100 includes crawler belts 103a and 103b driven by travel
motors 104a and 104b, respectively. The upper swing structure 101
is mounted on the lower structure 100 in a swingable manner via a
swing motor 105. The front shovel structure 102 is attached to the
front end of the upper structure 101 in a vertically rotatable
manner. The upper swing structure 101 has an engine room 106 and
the cab 107 mounted thereon. The engine 1 is installed within the
engine room 106, and the gate lock lever 7 (see FIG. 1) is
installed at the entrance to the cab seat 108 of the cab 107.
Installed at the left and right sides of the cab seat 108 are the
control lever units housing the remote control valves 25, 26, and
27 (see FIG. 2).
[0047] The front shovel structure 102 is a multi-joint structure
including a boom 111, an arm 112, and a bucket 113. The boom 111 is
rotated vertically by the expansion and contraction of a boom
cylinder 114. The arm 112 is rotated upward or downward and forward
or backward by the expansion and contraction of an arm cylinder
115. The bucket 113 is rotated upward or downward and forward or
backward by the expansion and contraction of a bucket cylinder
116.
[0048] The hydraulic motor 13 and hydraulic cylinders 14 and 15 of
FIG. 2 could be, for example, the swing motor 105, the arm cylinder
115, and the boom cylinder 114, respectively. While the hydraulic
drive system of FIG. 2 further includes other hydraulic actuators
and control valves for the motors 104a and 104b, the bucket
cylinder 116, and the like, FIG. 2 does not illustrate such
components.
[0049] It should be noted that the working machine to which the
invention is applied may instead be a wheel loader or a
wheel-mounted hydraulic excavator.
Control
[0050] FIG. 4 illustrates the functional blocks of the controller
4. The controller 4 includes a vehicle controller 41, an engine
controller 42, and a display controller 43. These controllers are
mutually connected via a communication line 44, forming a vehicle
network. The vehicle controller 41 receives command signals from
the engine control dial 2, detection signals from the position
detector 8 and the pressure sensor 47, and command signals from the
regeneration switch 38 while the engine controller 42 receives
detection signals from the speed detector 3, the differential
pressure detector 36, and the exhaust temperature detector 37.
[0051] The vehicle controller 41 is designed to control overall
vehicle operation including the hydraulic drive system. For
instance, the vehicle controller 41 controls the regulator 11a of
the hydraulic pump 11, thereby controlling the discharge pressure
and discharge flow-rate of the pump 11. The vehicle controller 11
also performs switch control of the solenoid valve 23 for gate
locking.
[0052] The engine controller 42 receives a command signal from the
engine control dial 2 through the communication line 44. The engine
controller 42 uses this command signal and a signal from the speed
detector 3 to control the speed and torque of the engine 1.
[0053] The engine controller 42 also receives a signal from the
differential pressure detector 36 to estimate the amount of
accumulated particulate matter and performs calculations for
regeneration control based on the estimate. Based on the
calculations, the engine controller 42 then controls the electronic
governor la and the fuel injector 39 (automatic regeneration
control).
[0054] The display controller 43 receives various signals and the
calculations results through the communication line 44 and
transmits display signals to the display device 6 so that such
information can be displayed on the screen 6a. If necessary, voice
signals are transmitted to the speaker 6c. The display controller
43 also allows the input of command signals from the control
switches 6b, part of the user interface.
[0055] The engine controller 42 includes a manual regeneration
function 42a. The manual regeneration function 42a receives a
signal from the differential pressure detector 36 to estimate the
amount of accumulated particulate matter and transmits a warning
signal to the display controller 43 based on the estimation. The
manual regeneration function 42a further receives a command signal
from the regeneration switch 38 via the communication line 44 and
then controls the electronic governor la and the fuel injector 39
(manual regeneration control).
[0056] A feature of the present embodiment is that the vehicle
controller 41 includes a status judgment function 41a, a warning
sound altering function 41b, and a memory 41c.
[0057] The status judgment function 41a judges the status of the
hydraulic excavator (whether it is in operation or not). When it is
in operation, the status judgment function 41a further judges
whether it is in a standby status or work-in-progress status.
[0058] The status judgment function 41a receives a signal from the
speed detector 3 through the communication line 44. When the actual
engine speed exceeds a low idle speed, the status judgment function
41a judges the excavator to be in operation. When, on the other
hand, the actual engine speed is less than the low idle speed, the
status judgment function 41a judges the excavator not to be in
operation.
[0059] When the excavator is judged to be in operation, the status
judgment function 41a receives signals from the position detector 8
and the pressure sensor 47. When the gate lock lever 7 is in the
lock position, the status judgment function 41a judges the
excavator to be in a standby status. When, on the other hand, the
gate lock lever 7 is in the unlock position and the pilot pressure
exceeds a given value, the excavator is judged to be in a
work-in-progress status.
[0060] The warning sound altering function 41b sets reference times
t1, t2, and t3 (t1<t2<t3) based on the judgment results
obtained by the status judgment function 41a. When the results
reveal that the excavator is in a standby status, the warning sound
altering function 41b reads reference times for standby status from
the memory 41c. When the results reveal that the excavator is in a
work-in-progress status, the warning sound altering function 41b
reads reference times for work-in-progress status from the memory
41c. The reference times t1, t2, and t3 for standby status are
shorter than the reference times t1, t2, and t3 for
work-in-progress status, respectively.
[0061] After receiving a warning signal from the manual
regeneration function 42a, the warning sound altering function 41b
starts time measurement from that point of time.
[0062] When the elapsed time exceeds the reference time t1 for
standby status (or for work-in-progress status), the warning sound
altering function 41b reads the voice data of a first warning sound
from the memory 41c and outputs the data to the display controller
43 in the form of a voice signal. When the elapsed time exceeds the
reference time t2 for standby status (or for work-in-progress
status), the warning sound altering function 41b then reads the
voice data of a second warning sound from the memory 41c and
outputs the data to the display controller 43 in the form of a
voice signal. When the elapsed time exceeds the reference time t3
for standby status (or for work-in-progress status), then, the
warning sound altering function 41b reads the voice data of a third
warning sound from the memory 41c and outputs the data to the
display controller 43 in the form of a voice signal.
[0063] FIG. 5 is a flowchart illustrating the calculations
performed by the controller 4.
[0064] We describe the manual regeneration control first. Note that
while the manual regeneration control is performed in parallel with
the automatic regeneration control, we describe only the former
control for simplification purposes.
[0065] The controller 4 first judges whether or not the amount of
particulate matter estimated based on a signal from the
differential pressure detector 36 is greater than a first
threshold, a value indicative of the necessity of manual
regeneration (Step S11). If not, Step S11 is repeated until the
estimated amount becomes greater than the first threshold.
[0066] After judging the estimated amount to be greater than the
first threshold in Step S11, the controller 4 outputs a warning
signal to prompt the operator to turn on the regeneration switch
38. This causes the screen 6a to display a warning prompting manual
regeneration (Step S12).
[0067] The controller 4 then judges whether the regeneration switch
38 has been turned on or not (Step S13). If not, the warning
continues to be displayed until the regeneration switch 38 is
turned on. During that time, the controller 4 also performs warning
sound control (described later in detail).
[0068] After judging the regeneration switch 38 to be turned on in
Step S13, the controller 4 starts manual regeneration control (Step
S13).
[0069] The regeneration control can be performed in the following
manner. The speed of the engine 1 is first controlled to a given
speed Na suitable for compulsory regeneration control. The given
speed Na is a middle speed that makes exhaust temperature higher
than the activation temperature of the oxidation catalyst 33. In
this control, the vehicle controller 41 changes the target speed of
the engine 1 from the target speed specified by the engine control
dial 2 to the given speed Na and outputs the given speed Na to the
engine controller 42 via the communication line 44. The engine
controller 42 then performs feedback control on the fuel injection
amount of the electronic governor la based on the given speed Na
and the actual engine speed detected by the speed detector 3,
thereby controlling the speed of the engine 1 to the given speed
Na.
[0070] After the exhaust temperature detected by the exhaust
temperature detector 37 increases up to a given value (a
temperature higher than the activation temperature of the oxidation
catalyst 33), the controller 4 then instructs the fuel injector 39
to inject fuel into the exhaust pipe 31. This allows unburnt fuel
components to be supplied to and oxidized by the catalyst 33. The
reaction heat obtained from the oxidation increases the exhaust
temperature further, burning off the particulate matter accumulated
on the filter 32. The exhaust temperature may instead be raised by
increasing the engine load by increasing the engine speed or
utilizing the hydraulic load effect.
[0071] During the regeneration control, the controller 4 judges
whether or not the estimated amount of particulate matter is less
than a second threshold, a value with which to judge the completion
of the regeneration (Step S15). If so, the manual regeneration
control is terminated (Step S16). If not, the regeneration control
is continued until the estimated amount becomes less than the
second threshold.
[0072] When the regeneration control is terminated, the target
engine speed is set back to the target speed specified by the
engine control dial 2 (i.e., low idle speed), and the operation of
the fuel injector 39 is stopped. Alternatively, it is also possible
to halt the engine 1 in place of setting the target engine speed
back to the target speed specified by the engine control dial 2
(i.e., low idle speed).
[0073] Described next is warning sound control.
[0074] The status of the hydraulic excavator is judged in advance
(Step S21). Based on the results (whether the excavator is in a
standby status or work-in-progress status), the controller 4 sets
the reference times t1, t2, and t3 for standby status or for
work-in-progress status (Step S22).
[0075] After a warning is displayed to prompt manual regeneration
in Step S12, the controller 4 starts time measurement from that
point of time (Step S23).
[0076] The controller 4 first judges whether the elapsed time has
exceeded the reference time t1 (Step S24). If not, Steps S13 and
S24 are repeated until the regeneration switch 38 is turned on or
until the elapsed time exceeds the reference time t1. When the
elapsed time exceeds the reference time t1, the controller 4
outputs a first warning sound (Step S25).
[0077] The controller 4 then judges whether the elapsed time has
exceeded the reference time t2 (Step S26). If not, Steps S13, S24,
and S25 are repeated until the regeneration switch 38 is turned on
or until the elapsed time exceeds the reference time t2, thus
continuing the output of the first warning sound. When the elapsed
time exceeds the reference time t2, a second warning sound is
output in place of the first warning sound (Step S27).
[0078] The controller 4 further judges whether the elapsed time has
exceeded the reference time t3 (Step S28). If not, Steps S13 and
S24 to S27 are repeated until the regeneration switch 38 is turned
on or until the elapsed time exceeds the reference time t3, thus
continuing the output of the second warning sound. When the elapsed
time exceeds the reference time t3, a third warning sound is output
in place of the second warning sound (Step S29).
[0079] After judging the regeneration switch 38 to be turned on in
Step S13, the controller 4 starts manual regeneration control (Step
S13). If, on the other hand, a particular amount of time has passed
since the output of the third warning sound and regeneration has
not been started yet, the controller 4 prohibits the regeneration
(not illustrated). This is because an excessive amount of
accumulated particulate matter may burn abruptly, increasing the
filter temperature excessively and damaging the filter.
Terms Used in Claims
[0080] Step S12 performed by the manual regeneration function 42a,
the display controller 43, and the screen 6a of the present
embodiment constitute "warning means" for prompting the operation
of the regeneration switch 38.
[0081] The speed detector 3, the position detector 8, the pressure
sensor 47, and Step S21 performed by the status judgment function
41a constitute "status judging means" for judging the status of
working machine.
[0082] Steps S23 to S29 performed by the warning sound altering
function 41b constitute "warning sound altering function" for
altering warning sounds when the amount of time during which the
working machine is being judged to be in operation exceeded
reference times after the display of a warning prompting manual
regeneration.
Operation
[0083] (1) Now described is the basic operation of the exhaust
purification system of Embodiment 1.
[0084] While the excavator is in operation, automatic regeneration
control is performed. However, the accumulation of particulate
matter proceeds if the automatic regeneration control is not
performed properly for some reason. When the accumulated PM amount
becomes higher than a first threshold, a warning message is
displayed on the screen 6a to prompt manual regeneration.
Regeneration control is started by the operator turning on the
regeneration switch 38. After the accumulated PM is burnt and the
accumulated PM amount becomes smaller than a second threshold, the
regeneration control is stopped (the process flows from S11 to S12,
to S13, to S14, to S15, and to S16).
[0085] During the excavation work by the hydraulic excavator, the
operator may fail to notice a warning prompting manual regeneration
if he is too focused on the work. Moreover, if he places high
priority on the completion of the work, he may ignore the manual
regeneration warning. If manual regeneration is not performed after
the warning, the accumulation of PM will proceed. Eventually, the
in-filter temperature may increase excessively due to the
combustion of a large amount of PM, damaging the DPF device.
[0086] Therefore, when the elapsed time since the display of the
manual regeneration warning exceeds the reference time t1 (but not
the reference time t2), the speaker 6c outputs a first warning
sound (e.g., three, short, low-volume beep sounds). When the
operator notices the first warning sound and turns on the
regeneration switch 38, regeneration control is started (the
process flows from S12 to S23, to S24, to S25, to S26, to S13, and
to S14).
[0087] However, because the excavator's work may often coincide
with other construction work at the construction site, the noise
may prevent the operator from noticing the first warning sound.
Thus, when the elapsed time since the display of the manual
regeneration warning exceeds the reference time t2 (but not the
reference time t3), the speaker 6c instead outputs a second warning
sound (e.g., five, long, medium-volume, low-pitched beep sounds).
When the operator notices the second warning sound and turns on the
regeneration switch 38, regeneration control is started (the
process flows from S25 to S26, to S27, to S28, to S13, and to
S14).
[0088] If manual regeneration is not performed after the second
warning sound, it is prompted with a louder sound. When the elapsed
time since the display of the manual regeneration warning exceeds
the reference time t3, the speaker 6c instead outputs a third
warning sound (e.g., a continuous, large-volume, lower-pitched beep
sound). When the operator notices the third warning sound and turns
on the regeneration switch 38, regeneration control is started (the
process flows from S25 to S26, to S27, to S28, to S13, and to
S14).
[0089] If manual regeneration is not performed after the third
warning sound and a particular amount of time has passed since the
third warning sound, regeneration is prohibited. This is because an
excessive amount of accumulated particulate matter may burn
abruptly, increasing the filter temperature excessively and
damaging the filter.
[0090] The above basic operation of the exhaust purification system
is based on the assumption that the hydraulic excavator is in
work-in-progress status. When the excavator is judged to be in
work-in-progress status, the reference times t1, t2, and t3 for
work-in-progress status are set (S21 to S22).
[0091] (2) Next described is the operation of the exhaust
purification system when the excavator is put on standby.
[0092] One of the tasks of the hydraulic excavator is to load
excavated soil onto dump trucks. The soil is often gathered at a
single location for the excavator to load it onto waiting dump
trucks. The dump trucks are used to transport the soil to another
location. When the dump trucks are small in number, the excavator
has to wait longer for a next dump to come.
[0093] When the hydraulic excavator is in standby status, the
exhaust temperature decreases drastically. Thus, self-regeneration
and automatic regeneration may not be performed properly, resulting
in further accumulation of particulate matter compared with
work-in-progress status.
[0094] Accordingly, when the excavator is judged to be in standby
status, the reference times t1, t2, and t3 for standby status are
set (S21 to S22). The reference times t1, t2, and t3 for standby
status are shorter than the reference times t1, t2, and t3 for
work-in-progress status, respectively. This means that the first,
second, and third warning sounds output during standby status are
output earlier than those output during work-in-progress status.
When the operator notices one of the warning sounds and turns on
the regeneration switch 38, regeneration control is started.
[0095] (3) When the engine 1 is halted during the output of any of
the warning sounds, all control is halted as well. In that case,
the elapsed time measured thus far is stored on the memory 41c.
When the key switch 5 is operated again to start the supply of
power to the controller 4, the display device 6, and so forth, the
elapsed time stored last will be read from the memory 41c, and a
warning sound is also output before the start-up of the engine
1.
Advantages
[0096] (1) When the elapsed time since the display of a manual
regeneration warning is short and the DPF device is less likely to
be damaged (than in the cases described below), the first warning
sound, or a low-volume beep sound, is output. Since the volume of
the first warning sound is low, the operator will not find it
annoying. By the operator noticing the first warning sound and
performing proper manual regeneration, damage to the DPF device can
be avoided.
[0097] When manual regeneration is not performed after the output
of the first warning sound and the elapsed time becomes longer, the
DPF device is more likely to be damaged. In that case, the speaker
6c outputs the second warning sound (louder than the first) and the
third warning sound (louder than the second). Since the second and
third warning sounds are louder beep sounds, the operator will
notice them easily. By the operator then performing proper manual
regeneration, damage to the DPF device can be avoided.
[0098] (2) In conventional techniques, the content of a warning is
changed based on an estimated amount of accumulated PM. Thus, if
the estimate has errors, the warning may not be changed properly.
Especially, when the estimate is smaller than the actual amount and
a warning is changed based on that estimate, judgment associated
with the alteration of the warning may be delayed. This delay could
be an indirect cause of DPF breakage because manual regeneration
cannot be performed properly (i.e., the start of the manual
regeneration is delayed).
[0099] In the present embodiment, by contrast, warning sounds are
changed based on elapsed time. This allows the warning sounds to be
changed more reliably without being affected by PM estimation
errors, and by the operator noticing the warning sounds and
performing manual regeneration, damage to the DPF device can be
avoided.
[0100] (3) While the hydraulic excavator is designed to do
excavation work and its work-in-progress status often lasts a long
period of time, it may occasionally be put on standby for a long
time depending on the work. During standby status, more particulate
matter may be accumulated than during work-in-progress status.
Thus, changing warning sounds based on the reference times for
work-in-progress status may delay judgment associated with the
alteration of the warning sounds.
[0101] Therefore, in the present embodiment, warning sounds are
changed based on the reference times for standby status while the
excavator is put on standby. This allows the warning sounds to be
changed more reliably without the associated judgment being
delayed. In that case as well, by the operator noticing the warning
sounds and performing manual regeneration, damage to the DPF device
can be avoided.
Modifications
[0102] (1) The present embodiment uses three warning sounds: the
first warning sound (e.g., three, short, low-volume, midrange beep
sounds), the second warning sound (e.g., five, long, medium-volume,
low-pitched beep sounds), and the third warning sound (e.g., a
continuous, large-volume, lower-pitched beep sound). The first
warning sound is changed to the second warning sound, and the
second warning sound is changed to the third warning sound. Note
however that this is meant to be an example, and the volume, tone,
length, or number of the warning sounds can be changed as
desired.
[0103] (2) While, in the present embodiment, a warning message
prompting manual regeneration is displayed (Step S12) based on the
PM amount estimated by the differential pressure detector 36, it
can instead be based on the elapsed time since the start of
excavation work so that PM estimation errors will not affect the
timing of the warning display.
[0104] (3) While, in the present embodiment, the warning sounds are
changed based on the elapsed time since the display of a warning
message, they can instead be changed based on an estimated PM
amount if the estimate is highly accurate.
[0105] (4) While, in the present embodiment, the warning sounds are
changed based the elapsed time, it is also possible to change a
warning message displayed on the screen 6a into ones attracting
more attention.
Embodiment 2
Problem Associated With Embodiment 1
[0106] Described below is the operation of the exhaust purification
system of Embodiment 1 when the excavator is shifted from standby
status back to work-in-progress status during the control by the
system. During standby status, more particulate matter is
accumulated than during work-in-progress status. Assume that the
excavator is shifted back to work-in-progress status and that the
reference times t1, t2, and t3 for work-in-progress status are set
again. In that case, using the reference times t1, t2, and t3 for
work-in-progress status based on the elapsed time measured during
standby status results in the alteration of warning sounds being
delayed.
[0107] This is discussed in greater detail with reference to FIG.
6. FIG. 6 is a graph illustrating the problem resulting from the
different reference times set for standby status and
work-in-progress status. The horizontal axis represents time while
the vertical axis represents the amount of accumulated PM. The
threshold Q represents the accumulated PM amount at which warning
sounds should be changed, and the reference time T for
work-in-progress status represents the time at which warning sounds
should be changed during work-in-progress status. The lower solid
line represents the accumulation of PM during work-in-progress
status. During standby status, particulate matter is assumed to be
accumulated X times as much as during work-in-progress status (X
being a positive number greater than 1). The upper solid line
represents the accumulation of PM during standby status. Thus, the
reference time T/X for standby status (i.e., the time at which the
threshold Q is reached during standby status) is calculated by
multiplying the reference time T for work-in-progress status by the
reciprocal of X (i.e., 1/X).
[0108] The dotted line represents the accumulation of PM when the
excavator is shifted from standby status to work-in-progress status
at Point A. When the excavator is judged to be in work-in-progress
status at Point A, the reference time T for work-in-progress status
is set again. However, the PM amount reaches the threshold Q at
Point B before the measured time reaches the reference time T for
work-in-progress status. This means that changing warning sounds
after the reference time T for work-in-progress status has been
reached is too late.
Configuration and Advantages of Embodiment 2
[0109] In Embodiment 2, the warning sound altering function 41b of
Embodiment 1 is allowed to have an elapsed-time converting function
41d (see FIG. 4).
[0110] FIG. 7 is a graph illustrating how the elapsed-time
converting function 41d works. Similar to FIG. 6, FIG. 7
illustrates a case where the excavator is shifted from standby
status to work-in-progress status at Point A, and the elapsed time
at Point A is denoted by t.
[0111] The elapsed-time converting function 41d calculates Point C
on the line that represents the PM accumulation during
work-in-progress status such that it becomes equal to the PM amount
at Point A. In FIG. 7, the converted elapsed time at Point C is
denoted by Xt. The converted elapsed time Xt is obtained by
assuming that the excavator has been in work-in-progress
status.
[0112] When the elapsed time measured is t, the warning sound
altering function 41b coverts the time t into the converted elapsed
time Xt, followed by the continuation of time measurement from the
time Xt. When the elapsed time reaches the reference time T for
work-in-progress status (i.e., the time at which the threshold Q is
reached), warning sounds are changed.
[0113] The elapsed-time converting function 41d of Embodiment 2
prevents warning sound alteration judgment from being delayed when
the excavator is shifted from standby status back to
work-in-progress status, thus ensuring a reliable alternation of
warning sounds. By the operator noticing the warning sounds and
performing manual regeneration properly, damage to the DPF device
can be avoided.
[0114] If, on the other hand, the excavator is shifted from
work-in-progress status back to standby status, the elapsed-time
converting function 41d instead calculates converted elapsed time
t/X when the elapsed time measured is t.
DESCRIPTION OF REFERENCE NUMERALS
[0115] 1: Diesel engine
[0116] 1a: Electronic governor
[0117] 2: Engine control dial
[0118] 3: Speed detector
[0119] 4: Controller
[0120] 5: Key switch
[0121] 6: Display device
[0122] 6a: Screen
[0123] 6b: Control switch
[0124] 6c: Speaker
[0125] 7: Gate lock lever
[0126] 8: Position detector
[0127] 11: Hydraulic pump
[0128] 12: Pilot pump
[0129] 13: Hydraulic motor
[0130] 14, 15: Hydraulic cylinder
[0131] 17 to 19: Flow-rate control valve
[0132] 20: Pilot hydraulic pressure source
[0133] 21: Pilot relief valve
[0134] 22: Main relief valve
[0135] 23: Solenoid valve
[0136] 24: Pilot hydraulic line
[0137] 25, 26, 27: Remote control valve
[0138] 28, 29: Operating lever
[0139] 31: Exhaust pipe
[0140] 32: Filter
[0141] 33: Oxidation catalyst
[0142] 34: DPF device
[0143] 36: Differential pressure detector
[0144] 37: Exhaust temperature detector
[0145] 38: Regeneration switch
[0146] 39: Fuel injector
[0147] 41: Vehicle controller
[0148] 41a: Status judgment function
[0149] 41b: Warning sound altering function
[0150] 41c: Memory
[0151] 41d: Elapsed-time converting function (Embodiment 2)
[0152] 42: Engine controller
[0153] 42a: Manual regeneration function
[0154] 43: Display controller
[0155] 44: Communication line
[0156] 46: Shuttle valve
[0157] 47: Pressure sensor
[0158] 100: Lower carrier structure
[0159] 102: Front shovel structure
[0160] 103a, 103b: Crawler belt
[0161] 104a, 104b: Travel motor
[0162] 105: Swing motor
[0163] 106: Engine room
[0164] 107: Cab
[0165] 108: Cab seat
[0166] 111: Boom
[0167] 112: Arm
[0168] 113: Bucket
[0169] 114: Boom cylinder
[0170] 115: Arm cylinder
[0171] 116: Bucket cylinder
* * * * *