U.S. patent application number 14/767475 was filed with the patent office on 2016-09-29 for wheel loader.
The applicant listed for this patent is KOMATSU LTD.. Invention is credited to Masaaki Imaizumi.
Application Number | 20160281323 14/767475 |
Document ID | / |
Family ID | 54009238 |
Filed Date | 2016-09-29 |
United States Patent
Application |
20160281323 |
Kind Code |
A1 |
Imaizumi; Masaaki |
September 29, 2016 |
Wheel Loader
Abstract
A wheel loader includes: an operating state detecting unit
detecting an operating state; a target setting unit setting a
relationship between a target position of a working equipment and a
travel distance of the wheel loader for the operating state
detected by the operating state detecting unit; a travel distance
detecting unit detecting the travel distance of the wheel loader;
and a working equipment controlling unit moving a boom and a bucket
to the target position of the working equipment determined
depending on the travel distance detected by the travel distance
detecting unit.
Inventors: |
Imaizumi; Masaaki;
(Mooka-shi, Tochigi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KOMATSU LTD. |
Minato-ku, Tokyo |
|
JP |
|
|
Family ID: |
54009238 |
Appl. No.: |
14/767475 |
Filed: |
March 25, 2015 |
PCT Filed: |
March 25, 2015 |
PCT NO: |
PCT/JP2015/059222 |
371 Date: |
August 12, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E02F 9/2296 20130101;
E02F 3/434 20130101; E02F 9/265 20130101; E02F 3/283 20130101; E02F
9/268 20130101; E02F 9/2029 20130101; E02F 9/2004 20130101; E02F
9/0841 20130101 |
International
Class: |
E02F 3/43 20060101
E02F003/43; E02F 9/20 20060101 E02F009/20; E02F 3/28 20060101
E02F003/28 |
Claims
1. A wheel loader comprising: working equipment comprising a boom
and a bucket attached to the boom; an operating state detecting
unit configured to detect an operating state of the wheel loader; a
target setting unit configured to set a relationship between a
target position of the working equipment and a travel distance of
the wheel loader for the operating state detected by the operating
state detecting unit; a travel distance detecting unit configured
to detect the travel distance of the wheel loader; and a working
equipment controlling unit configured to move the boom and the
bucket to the target position of the working equipment determined
depending on the travel distance detected by the travel distance
detecting unit.
2. The wheel loader according to claim 1, wherein the operating
state detecting unit comprises: a load determining unit configured
to determine whether or not the bucket is loaded; and a
forward/reverse travel determining unit configured to determine
whether the wheel loader travels forward or reverses, when the load
determining unit determines that the bucket is loaded and the
forward/reverse travel determining unit determines that the wheel
loader reverses, the operating state is detected to be a loaded
reverse traveling state, the target setting unit sets the
relationship between the target position of the working equipment
and the travel distance of the wheel loader for the loaded reverse
traveling state, and the working equipment controlling unit moves
the boom and the bucket to the target position of the working
equipment determined depending on the travel distance detected by
the travel distance detecting unit when the operating state is the
loaded reverse traveling state.
3. The wheel loader according to claim 1, wherein the operating
state detecting unit comprises: a load determining unit configured
to determine whether or not the bucket is loaded; and a
forward/reverse travel determining unit configured to determine
whether the wheel loader travels forward or reverses, when the load
determining unit determines that the bucket is loaded and the
forward/reverse travel determining unit determines that the wheel
loader travels forward, the operating state is detected to be a
loaded forward traveling state, the target setting unit sets the
relationship between the target position of the working equipment
and the travel distance of the wheel loader for the loaded forward
traveling state, and the working equipment controlling unit moves
the boom and the bucket to the target position of the working
equipment determined depending on the travel distance detected by
the travel distance detecting unit when the operating state is the
loaded forward traveling state.
4. The wheel loader according to claim 1, wherein the operating
state detecting unit comprises: a load determining unit configured
to determine whether or not the bucket is loaded; and a
forward/reverse travel determining unit configured to determine
whether the wheel loader travels forward or reverses, when the load
determining unit determines that the bucket is unloaded and the
forward/reverse travel determining unit determines that the wheel
loader reverses, the operating state is detected to be an unloaded
reverse traveling state, the target setting unit sets the
relationship between the target position of the working equipment
and the travel distance of the wheel loader for the unloaded
reverse traveling state, and the working equipment controlling unit
moves the boom and the bucket to the target position of the working
equipment determined depending on the travel distance detected by
the travel distance detecting unit when the operating state is the
unloaded reverse traveling state.
5. The wheel loader according to claim 2, wherein the target
setting unit: sets a boom angle in proportion to the travel
distance to define a target position of the boom for the loaded
reverse traveling state, the boom angle varying from a value at a
start of a movement of the boom in the loaded reverse traveling
state to a value at which the boom is to get horizontal when the
travel distance of the wheel loader reaches a distance L1; and sets
a bucket cylinder length where the bucket is maintained at a
tilting position in accordance with the boom angle to define a
target portion of the bucket for the loaded reverse traveling
state.
6. The wheel loader according to claim 3, wherein the target
setting unit sets a distance L2 as a target travel distance for the
loaded forward traveling state, a first interim distance less than
the distance L2, and a second interim distance equal to or more
than the first interim distance but less than the distance L2, when
the travel distance is less than the first interim distance, the
target setting unit: sets a first boom angle at which the boom is
to get horizontal to define a target position of the boom for the
loaded forward traveling state; and sets a first bucket cylinder
length where the bucket is maintained at a tilting position to
define a target position of the bucket for the loaded forward
traveling state, when the travel distance is equal to or more than
the first interim distance but less than the second interim
distance, the target setting unit: sets a second boom angle in
proportion to the travel distance to define the target position of
the boom for the loaded forward traveling state, the second boom
angle varying from a value at a time when the travel distance
reaches the first interim distance to a value at which the boom is
to reach a preset lifted positioner position when the travel
distance reaches the second interim distance; and sets a second
bucket cylinder length where the bucket is maintained at the
tilting position in accordance with the second boom angle to define
a target portion of the bucket for the loaded forward traveling
state, and when the travel distance is in a range from the second
interim distance to the distance L2, the target setting unit: sets
a third boom angle at which the boom is to reach the lifted
positioner position to define the target position of the boom for
the loaded forward traveling state; and sets a third bucket
cylinder length where the bucket is maintained at the tilting
position to define the target position of the bucket for the loaded
forward traveling state.
7. The wheel loader according to claim 4, wherein the target
setting unit sets a distance L2 as a target travel distance for the
unloaded reverse traveling state, a third interim distance less
than the distance L2, and a fourth interim distance equal to or
more than the third interim distance but less than the distance L2,
when the travel distance is less than the third interim distance,
the target setting unit: sets a first boom angle at which the boom
is to reach a preset lifted positioner position to define a target
position of the boom for the unloaded reverse traveling state; and
sets a first bucket cylinder length in proportion to the travel
distance to define a target position of the bucket for the unloaded
reverse traveling state, the first bucket cylinder length varying
from a value at a start of a movement of the bucket in the unloaded
reverse traveling state to a value where the bucket is to reach a
preset initial position when the travel distance of the wheel
loader reaches the third interim distance, when the travel distance
is equal to or more than the third interim distance but less than
the fourth interim distance, the target setting unit: sets a second
boom angel in proportion to the travel distance to define the
target position of the boom for the unloaded reverse traveling
state, the second boom angle varying from a value at a time when
the travel distance reaches the third interim distance to a value
at which the boom is to get horizontal when the travel distance
reaches the fourth interim distance; and sets a second bucket
cylinder length where the bucket is maintained at the preset
initial position to define the target position of the bucket for
the unloaded reverse traveling state, and when the travel distance
is in a range from the fourth interim distance to the distance L2,
the target setting unit: sets a third boom angle in proportion to
the travel distance to define the target position of the boom for
the unloaded reverse traveling state, the third boom angle varying
from a value at a time when the travel distance reaches the fourth
interim distance to a value at which the boom is to reach a preset
lowered positioner position when the travel distance reaches the
distance L2; and sets a third bucket cylinder length where the
bucket is maintained at the preset initial position to define the
target position of the bucket for the unloaded reverse traveling
state.
8. The wheel loader according to claim 1, further comprising: a
boom position detecting unit configured to detect a current
position of the boom; and a bucket position detecting unit
configured to detect a current position of the bucket, wherein the
target setting unit calculates a current target position of each of
the boom and the bucket from the current travel distance detected
by the travel distance detecting unit, the working equipment
controlling unit calculates a deviation between the current target
position of the boom and the current position of the boom detected
by the boom position detecting unit and a deviation between the
current target position of the bucket and the current position of
the bucket detected by the bucket position detecting unit, and each
of the boom and the bucket is moved based on the deviations.
9. The wheel loader according to claim 1, further comprising: a
boom lever for operating the boom; and a bucket lever for operating
the bucket, wherein the working equipment controlling unit adds
displacement of the boom lever and the bucket lever by a manual
operation to move the working equipment.
10. The wheel loader according to claim 1, further comprising: a
boom lever for operating the boom; and a bucket lever for operating
the bucket, wherein the working equipment controlling unit stores a
travel distance at a time when the working equipment reaches the
target position when displacement of the boom lever and the bucket
lever by a manual operation is added, and the target setting unit
corrects the travel distance of the wheel loader defined by the
relationship between the position of the working equipment and the
travel distance of the wheel loader with the travel distance stored
when the working equipment reaches the target position.
Description
TECHNICAL FIELD
[0001] The present invention relates to a wheel loader.
BACKGROUND ART
[0002] A wheel loader often repeats excavation and loading for the
excavated substance on, for instance, the vessel of a dump truck.
In particular, a large-sized wheel loader often repeats a so-called
V-shape operation for a long time, which results in an increased
workload on an operator. Accordingly, in order to reduce the
workload on the operator, a mode for assisting loading on a vessel
or the like may be installed in a wheel loader provided with
semi-automatic boom and bucket (see, for instance, Patent
Literature 1).
[0003] In the wheel loader of Patent Literature 1, loading from the
bucket is automatically started when a predetermined operation is
performed on a boom operation lever. The operator can thus only
have to operate the boom lever to perform loading from the
bucket.
CITATION LIST
Patent Literature(s)
[0004] Patent Literature 1: JP-A-2009-197425
SUMMARY OF THE INVENTION
Problem(s) to be Solved by the Invention
[0005] When a wheel loader is used for excavation, a distal end of
the boom is lowered to be positioned near the ground. In contrast,
when a wheel loader is used for loading, the distal end of the boom
is lifted to be positioned above the vessel of a haulage vehicle or
a dump truck. Accordingly, in order to efficiently repeat
excavation and loading, the wheel loader needs to travel with
working equipment being moved.
[0006] The operator thus needs to operate the working equipment
with his/her right hand while operating the wheel loader by, for
instance, a combination of an accelerator operation (right foot), a
brake operation (left foot) and a steering operation (left hand).
Such a complicated operation entails an increased workload, so that
an efficient operation is difficult for, especially, an
inexperienced operator.
[0007] An object of the invention is to provide a wheel loader
capable of easily transporting and loading, for instance, excavated
soil and sand.
Means for Solving the Problem(s)
[0008] According to an aspect of the invention, a wheel loader
includes: working equipment including a boom and a bucket attached
to the boom; an operating state detecting unit configured to detect
an operating state of the wheel loader; a target setting unit
configured to set a relationship between a target position of the
working equipment and a travel distance of the wheel loader for the
operating state detected by the operating state detecting unit; a
travel distance detecting unit configured to detect the travel
distance of the wheel loader; and a working equipment controlling
unit configured to move the boom and the bucket to the target
position of the working equipment determined depending on the
travel distance detected by the travel distance detecting unit.
[0009] In the aspect, when the wheel loader is in any one of
predetermined operating states, including a loaded reverse
traveling state, a loaded forward traveling state and an unloaded
reverse traveling state, and travels, the target setting unit sets
a target position of the working equipment in accordance with the
operating state and the travel distance of the wheel loader, and
the working equipment controlling unit moves the boom and the
bucket to the target position. The exemplary embodiment thus
eliminates a necessity for an operator to operate the boom lever
and/or the bucket lever to move the working equipment
simultaneously when operating a steering and/or an accelerator. The
operator is merely required to mainly operate the steering,
accelerator and brake. Consequently, even an inexperienced operator
can easily operate the wheel loader.
[0010] Further, the working equipment is automatically moved to an
appropriate position during the travel of the wheel loader, which
results in an improved operating efficiency and a fuel-saving
driving as compared with an instance where the working equipment is
moved after the travel of the wheel loader.
[0011] In the wheel loader of the above aspect, it is preferable
that the operating state detecting unit include: a load determining
unit configured to determine whether or not the bucket is loaded;
and a forward/reverse travel determining unit configured to
determine whether the wheel loader travels forward or reverses,
when the load determining unit determines that the bucket is loaded
and the forward/reverse travel determining unit determines that the
wheel loader reverses, the operating state be detected to be a
loaded reverse traveling state, the target setting unit set the
relationship between the target position of the working equipment
and the travel distance of the wheel loader for the loaded reverse
traveling state, and the working equipment controlling unit move
the boom and the bucket to the target position of the working
equipment determined depending on the travel distance detected by
the travel distance detecting unit when the operating state is the
loaded reverse traveling state.
[0012] In the wheel loader of the above aspect, it is preferable
that the operating state detecting unit include: a load determining
unit configured to determine whether or not the bucket is loaded;
and a forward/reverse travel determining unit configured to
determine whether the wheel loader travels forward or reverses,
when the load determining unit determines that the bucket is loaded
and the forward/reverse travel determining unit determines that the
wheel loader travels forward, the operating state be detected to be
a loaded forward traveling state, the target setting unit set the
relationship between the target position of the working equipment
and the travel distance of the wheel loader for the loaded forward
traveling state, and the working equipment controlling unit move
the boom and the bucket to the target position of the working
equipment determined depending on the travel distance detected by
the travel distance detecting unit when the operating state is the
loaded forward traveling state.
[0013] In the wheel loader of the above aspect, it is preferable
that the operating state detecting unit include: a load determining
unit configured to determine whether or not the bucket is loaded;
and a forward/reverse travel determining unit configured to
determine whether the wheel loader travels forward or reverses,
when the load determining unit determines that the bucket is
unloaded and the forward/reverse travel determining unit determines
that the wheel loader reverses, the operating state be detected to
be an unloaded reverse traveling state, the target setting unit set
the relationship between the target position of the working
equipment and the travel distance of the wheel loader for the
unloaded reverse traveling state, and the working equipment
controlling unit move the boom and the bucket to the target
position of the working equipment determined depending on the
travel distance detected by the travel distance detecting unit when
the operating state is the unloaded reverse traveling state.
[0014] In the wheel loader of the above aspect, it is preferable
that the target setting unit: set a boom angle in proportion to the
travel distance to define a target position of the boom for the
loaded reverse traveling state, the boom angle varying from a value
at a start of a movement of the boom in the loaded reverse
traveling state to a value at which the boom is to get horizontal
when the travel distance of the wheel loader reaches a distance L1;
and set a bucket cylinder length where the bucket is maintained at
a tilting position in accordance with the boom angle to define a
target portion of the bucket for the loaded reverse traveling
state.
[0015] In the wheel loader of the above aspect, it is preferable
that the target setting unit set a distance L2 as a target travel
distance for the loaded forward traveling state, a first interim
distance less than the distance L2, and a second interim distance
equal to or more than the first interim distance but less than the
distance L2, when the travel distance is less than the first
interim distance, the target setting unit: set a first boom angle
at which the boom is to get horizontal to define a target position
of the boom for the loaded forward traveling state; and set a first
bucket cylinder length where the bucket is maintained at a tilting
position to define a target position of the bucket for the loaded
forward traveling state, when the travel distance is equal to or
more than the first interim distance but less than the second
interim distance, the target setting unit: set a second boom angle
in proportion to the travel distance to define the target position
of the boom for the loaded forward traveling state, the second boom
angle varying from a value at a time when the travel distance
reaches the first interim distance to a value at which the boom is
to reach a preset lifted positioner position when the travel
distance reaches the second interim distance; and set a second
bucket cylinder length where the bucket is maintained at the
tilting position in accordance with the second boom angle to define
a target portion of the bucket for the loaded forward traveling
state, and when the travel distance is in a range from the second
interim distance to the distance L2, the target setting unit: set a
third boom angle at which the boom is to reach the lifted
positioner position to define the target position of the boom for
the loaded forward traveling state; and set a third bucket cylinder
length where the bucket is maintained at the tilting position to
define the target position of the bucket for the loaded forward
traveling state.
[0016] In the wheel loader of the above aspect, it is preferable
that the target setting unit set a distance L2 as a target travel
distance for the unloaded reverse traveling state, a third interim
distance less than the distance L2, and a fourth interim distance
equal to or more than the third interim distance but less than the
distance L2, when the travel distance is less than the third
interim distance, the target setting unit: set a first boom angle
at which the boom is to reach a preset lifted positioner position
to define a target position of the boom for the unloaded reverse
traveling state; and set a first bucket cylinder length in
proportion to the travel distance to define a target position of
the bucket for the unloaded reverse traveling state, the first
bucket cylinder length varying from a value at a start of a
movement of the bucket in the unloaded reverse traveling state to a
value where the bucket is to reach a preset initial position when
the travel distance of the wheel loader reaches the third interim
distance, when the travel distance is equal to or more than the
third interim distance but less than the fourth interim distance,
the target setting unit: set a second boom angel in proportion to
the travel distance to define the target position of the boom for
the unloaded reverse traveling state, the second boom angle varying
from a value at a time when the travel distance reaches the third
interim distance to a value at which the boom is to get horizontal
when the travel distance reaches the fourth interim distance; and
set a second bucket cylinder length where the bucket is maintained
at the preset initial position to define the target position of the
bucket for the unloaded reverse traveling state, and when the
travel distance is in a range from the fourth interim distance to
the distance L2, the target setting unit: set a third boom angle in
proportion to the travel distance to define the target position of
the boom for the unloaded reverse traveling state, the third boom
angle varying from a value at a time when the travel distance
reaches the fourth interim distance to a value at which the boom is
to reach a preset lowered positioner position when the travel
distance reaches the distance L2; and set a third bucket cylinder
length where the bucket is maintained at the preset initial
position to define the target position of the bucket for the
unloaded reverse traveling state.
[0017] It is preferable that the wheel loader of the above aspect
further include a boom position detecting unit configured to detect
a current position of the boom; and a bucket position detecting
unit configured to detect a current position of the bucket, in
which the target setting unit calculates a current target position
of each of the boom and the bucket from the current travel distance
detected by the travel distance detecting unit, the working
equipment controlling unit calculates a deviation between the
current target position of the boom and the current position of the
boom detected by the boom position detecting unit and a deviation
between the current target position of the bucket and the current
position of the bucket detected by the bucket position detecting
unit, and each of the boom and the bucket is moved based on the
deviations.
[0018] It is preferable that the wheel loader of the above aspect
further include a boom lever for operating the boom; and a bucket
lever for operating the bucket, in which the working equipment
controlling unit adds displacement of the boom lever and the bucket
lever by a manual operation to move the working equipment.
[0019] It is preferable that the wheel loader of the above aspect
further include a boom lever for operating the boom; and a bucket
lever for operating the bucket, in which the working equipment
controlling unit stores a travel distance at a time when the
working equipment reaches the target position when displacement of
the boom lever and the bucket lever by a manual operation is added,
and the target setting unit corrects the travel distance of the
wheel loader defined by the relationship between the position of
the working equipment and the travel distance of the wheel loader
with the travel distance stored when the working equipment reaches
the target position.
BRIEF DESCRIPTION OF DRAWING(S)
[0020] FIG. 1 is a side view of a wheel loader according to an
exemplary embodiment of the invention.
[0021] FIG. 2 schematically illustrates a drive mechanism for
working equipment.
[0022] FIG. 3 is a block diagram showing an arrangement of a
working equipment controller.
[0023] FIG. 4 schematically illustrates a V-shape operation of the
wheel loader.
[0024] FIG. 5 schematically illustrates a process of the V-shape
operation.
[0025] FIG. 6 is a flow chart showing a working equipment
controlling process for the V-shape operation.
[0026] FIG. 7 is a graph showing a relationship between a travel
distance and a target position of the working equipment in a loaded
reverse traveling state.
[0027] FIG. 8 is a graph showing a relationship between the travel
distance and the target position of the working equipment in a
loaded forward traveling state.
[0028] FIG. 9 is a graph showing a relationship between the travel
distance and the target position of the working equipment in an
unloaded reverse traveling state.
[0029] FIG. 10 is a flow chart showing a working equipment
controlling process in the loaded reverse traveling state.
[0030] FIG. 11 is a flow chart showing a working equipment
controlling process in the loaded forward traveling state.
[0031] FIG. 12 is a flow chart showing a working equipment
controlling process in the unloaded reverse traveling state.
[0032] FIG. 13 is a flow chart showing the working equipment
controlling process in the unloaded reverse traveling state.
[0033] FIG. 14 is a graph showing a relationship between a boom
deviation angle and a target flow rate.
[0034] FIG. 15 is a graph showing a relationship between a bucket
deviation length and the target flow rate.
DESCRIPTION OF EMBODIMENT(S)
Overall Arrangement of Wheel Loader
[0035] FIG. 1 is a side view of a wheel loader 1 according to an
exemplary embodiment of the invention. The wheel loader 1 is a
large-sized wheel loader 1 intended to be used in mines and the
like.
[0036] The wheel loader 1 includes a vehicle body 2 including a
front vehicle body 2A and a rear vehicle body 2B. The front vehicle
body 2A has a front side (the left side in FIG. 1) provided with
hydraulic working equipment 3 including an excavating/loading
bucket 31, a boom 32, a bell crank 33, a connecting link 34, a
bucket cylinder 35 and a boom cylinder 36.
[0037] The rear vehicle body 2B includes a rear vehicle body frame
5 formed from a thick metal plate or the like. The rear vehicle
body frame 5 has a front side provided with a box-shaped cab 6 in
which an operator is to be seated and a rear side where, for
instance, an engine (not shown) and a hydraulic pump configured to
be driven by the engine are mounted.
Drive Mechanism for Working Equipment
[0038] FIG. 2 schematically illustrates a drive mechanism for the
working equipment 3. The wheel loader 1 includes a working
equipment controller 10, an engine 11 and a power take-off (PTO)
12. The PTO 12 distributes an output from the engine 11 to a travel
system for driving wheels (tires) 7 and a hydraulic system for
driving the working equipment 3.
Arrangement of Travel System
[0039] The travel system, which is a mechanism (traveling unit)
allowing the wheel loader 1 to travel, includes not only a
transmission and an axle (both not shown) but also a torque
converter (T/C) 15. A power outputted from the engine 11 is
transmitted to the wheels 7 through the PTO 12, the torque
converter 15, the transmission and the axle.
Arrangement of Hydraulic System
[0040] The hydraulic system 30 is a mechanism for driving mainly
the working equipment 3 (e.g., the boom 32 and the bucket 31). The
hydraulic system includes: a hydraulic pump 21 for the working
equipment driven by the PTO 12; hydraulic pilot valves including a
bucket operation valve 22 and a boom operation valve 23 provided in
a discharge circuit of the hydraulic pump 21; solenoid proportional
pressure control valves 24, 25 for the bucket independently
connected to pilot-pressure receiving portions of the bucket
operation valve 22; and solenoid proportional pressure control
valves 26, 27 for the boom independently connected to
pilot-pressure receiving portions of the boom operation valve
23.
[0041] The solenoid proportional pressure control valves 24 to 27
are connected to a pilot pump (not shown) to independently control
the supply of a hydraulic oil to the pilot-pressure receiving
portions in accordance with a control signal from the working
equipment controller 10.
[0042] Specifically, the solenoid proportional pressure control
valve 24 switches the bucket operation valve 22 so that the bucket
cylinder 35 is retracted to move the bucket 31 to a loading
position. Similarly, the solenoid proportional pressure control
valve 25 switches the bucket operation valve 22 so that the bucket
cylinder 35 is extended to move the bucket 31 to a tilting
position.
[0043] The solenoid proportional pressure control valve 26 switches
the boom operation valve 23 so that the boom cylinder 36 is
retracted to lower the boom 32. Similarly, the solenoid
proportional pressure control valve 27 switches the boom operation
valve 23 so that the boom cylinder 36 is extended to raise the boom
32.
Devices Connected to Working Equipment Controller
[0044] As shown in FIG. 3, the working equipment controller 10 is
connected to: a boom lever 41 and a bucket lever 42 both disposed
in the cab 6; a semi-auto mode selecting unit 431 and an approach
length setting unit 432 both provided to a monitor 43 disposed in
the cab 6; a boom angle sensor 44; a bucket angle sensor 45; a
boom-bottom pressure sensor 46; an engine controller 47; and a
transmission controller 48.
[0045] The boom lever 41 includes a lever angle sensor for
detecting a lever angle. When an operator operates the boom lever
41, the lever angle sensor detects a lever angle corresponding to
displacement of the boom lever 41, and outputs the lever angle in
the form of a boom lever signal to the working equipment controller
10.
[0046] The bucket lever 42 includes a lever angle sensor for
detecting a lever angle. When an operator operates the bucket lever
42, the lever angle sensor detects a lever angle corresponding to
displacement of the bucket lever 42, and outputs the lever angle in
the form of a bucket lever signal to the working equipment
controller 10.
[0047] The semi-auto mode selecting unit 431 displays a mode
selection button on the monitor 43. When an operator operates the
mode selection button to select a semi-auto loading mode, the
semi-auto mode selecting unit 431 outputs an ON signal as a
semi-auto mode selection signal and, otherwise, outputs an OFF
signal as the semi-auto mode selection signal.
[0048] As shown in FIG. 4, the approach length setting unit 432
sets travel distances for a V-shape operation, including: a travel
distance L1 for the wheel loader 1 to be reversed with, for
instance, soil and sand being loaded in the bucket 31 after
excavation of the soil and sand is completed; and a travel distance
L2 for the wheel loader 1 to be moved toward a dump truck 60 after
being reversed for the travel distance L1 and stopped. In FIG. 4, L
represents the entire length of the wheel loader 1. L1 and L2 are
each provided in the form of a ratio to the entire vehicle length L
of the wheel loader 1, and respective default values thereof are:
L1=1 (equal to the entire vehicle length) and L2=0.8 (equal to 80%
of the entire vehicle length). The approach length setting unit 432
displays the respective default values "1" and "0.8" of the
approach lengths L1, L2 on the monitor 43. When an operator changes
these numerical values, the approach length setting unit 432 stores
the inputted values as preset values and outputs the inputted
values to the working equipment controller 10.
[0049] The boom angle sensor 44, which may include a rotary encoder
provided to an attached portion (a support shaft) of the boom 32
relative to the vehicle body 2 as shown in FIG. 2, detects a boom
angle between the center axis of the boom 32 and a horizontal axis
and outputs the detection signal. The boom angle sensor 44 thus
serves as a boom position detecting unit. The center axis of the
boom 32, which is represented by a line Y-Y in FIG. 2, connects the
attached portion of the boom 32 (i.e., the center of the support
shaft) relative to the vehicle body 2 and an attached portion of
the bucket 31 (the center of a bucket support shaft). Specifically,
when the line Y-Y in FIG. 2 is set along the horizontal axis, the
boom angle sensor 44 outputs a boom angle of zero degree. Further,
the boom angle sensor 44 outputs a positive value when a distal end
of the boom 32 is lifted from a position of the zero-degree boom
angle, and outputs a negative value when the distal end of the boom
32 is lowered.
[0050] The bucket angle sensor 45, which may include a rotary
encoder provided to a rotation shaft of the bell crank 33, outputs
zero degree when the bucket 31 is in contact with the ground with a
blade edge of the bucket 31 being horizontal on the ground.
Further, the bucket angle sensor 45 outputs a positive value when
the bucket 31 is moved toward the tilting position (upward), and
outputs a negative value when the bucket 31 is moved toward the
loading position (downward). The bucket angle sensor 45 thus serves
as a bucket position detecting unit.
[0051] The boom-bottom pressure sensor 46 detects a boom-bottom
pressure of the boom cylinder 36. The boom-bottom pressure is
increased when the bucket 31 is loaded, and decreased when the
bucket 31 is unloaded.
[0052] The engine controller 47 communicates with the working
equipment controller 10 through a controller area network (CAN),
and outputs engine operation information including the speed of the
engine 11 to the working equipment controller 10.
[0053] The transmission controller 48 communicates with the working
equipment controller 10 through the CAN, and outputs FR information
and vehicle speed information to the working equipment controller
10, the FR information indicating a travel direction of the wheel
loader 1 (i.e., forward or reverse) selected using an FR lever 49,
the vehicle speed information being received from a vehicle speed
sensor 50. It should be noted that the vehicle speed sensor 50 is
configured to detect the vehicle speed based on, for instance, the
rotation of drive shaft(s) of the tire(s) 7, and the vehicle speed
information detected by the vehicle speed sensor 50 is outputted to
the working equipment controller 10 via the transmission controller
48.
Arrangement of Working Equipment Controller
[0054] The working equipment controller 10 includes an operating
state detecting unit 110, a target setting unit 120, a travel
distance detecting unit 130, a working equipment controlling unit
140, and a storage 150.
[0055] The operating state detecting unit 110 includes a load
determining unit 111 and a forward/reverse travel determining unit
112. The load determining unit 111 determines whether or not the
bucket 31 is loaded based on an output value from the boom-bottom
pressure sensor 46.
[0056] The forward/reverse travel determining unit 112 determines
whether the wheel loader 1 is in a forward traveling state or a
reverse traveling state based on the FR information outputted from
the transmission controller 48 in accordance with an operation on
the FR lever 49.
Operating State Detecting Unit
[0057] The operating state detecting unit 110 detects an operating
state based on the determination result of the load determining
unit 111 and the determination result of the forward/reverse travel
determining unit 112. In the exemplary embodiment, the operating
state detecting unit 110 is configured to at least detect: a loaded
reverse traveling state where the wheel loader 1 is reversed after
excavation is completed; a loaded forward traveling state where the
wheel loader 1 in a loaded state is moved forward to transport the
load to the dump truck 60 or the like; and an unloaded reverse
traveling state where the wheel loader 1 is reversed after
discharging the load onto the dump truck 60 or the like.
Target Setting Unit
[0058] Based on the operating state detected by the operating state
detecting unit 110, the target setting unit 120 determines a
relationship between a travel distance of the wheel loader 1 and a
target position of the working equipment 3. In the exemplary
embodiment, the relationship is determined by assigning a current
travel distance to a numerical expression for calculating the
target position of the working equipment 3 (i.e., the boom angle of
the boom 32 and the bucket cylinder length of the bucket 31) as
described later. Alternatively, the relationship between the travel
distance and the target position may be stored in the form of a
table.
Travel Distance Detecting Unit
[0059] The travel distance detecting unit 130 receives the vehicle
speed information detected by the vehicle speed sensor 50 from the
transmission controller 48, and calculates the current travel
distance of the wheel loader 1.
Working Equipment Controlling Unit
[0060] Based on the various pieces of inputted information, the
working equipment controlling unit 140 outputs control signal(s) to
the solenoid proportional pressure control valves 24 to 27 to
actuate the bucket 31 and/or the boom 32.
[0061] Further, the working equipment controller 10 outputs an
indicator command and/or a buzzer command to the monitor 43. Upon
reception of the indicator command, the monitor 43 controls the
display of an indicator 435 provided to the monitor 43 to present
information to an operator.
[0062] Upon reception of the buzzer command, the monitor 43, which
is provided with a buzzer 436 capable of beeping, activates the
buzzer 436 to beep to warn an operator. The storage 150 stores not
only various pieces of data inputted to the working equipment
controller 10 but also various parameters required for controlling
the working equipment 3.
V-shape Operation Processes
[0063] Next, the V-shape operation by the wheel loader 1 will be
described with reference to FIGS. 4 and 5. The V-shape operation
includes the following plurality of operation processes.
1. Unloaded Stop to Excavation
[0064] A state where front ends of front ones of the tires 7 of the
wheel loader 1 in an unloaded state (i.e., the bucket 31 is
unloaded with a load such as soil and sand) are positioned on a
spot A as shown in FIG. 4 is referred to as an unloaded stopped
state (a start position).
[0065] Subsequently, an operator drives the wheel loader 1 in the
unloaded state forward to a bank or the like as shown in FIG. 5(A).
Specifically, the operator should preferably drive the wheel loader
1 forward for a distance L1 until the front ends of the tires 7
reach a spot B, as shown in FIG. 4.
[0066] The bucket 31 then performs excavation of the bank, and soil
and sand is loaded in the bucket 31 as shown in FIG. 5(B).
2. Completion of Excavation to Loaded Reverse Travel
[0067] As shown in FIG. 5(C), after the completion of the
excavation, the operator reverses the wheel loader 1 in the loaded
state with the bucket 31 being loaded with, for instance, soil and
sand to an unloaded stop position (the position of the spot A in
FIG. 4). In other words, the wheel loader 1 is reversed for the
distance L1.
3. Loaded Reverse Travel to Loaded Forward Travel
[0068] After stopping the wheel loader 1 at the unloaded stop
position, the operator drives the wheel loader 1 in the loaded
state forward to the dump truck 60 as shown in FIG. 5(D). As shown
in FIG. 4, an angle difference .theta. between a direction for the
wheel loader 1 to face the bank and a direction for the wheel
loader 1 to face the dump truck 60 usually falls approximately
within a range from 45 to 60 degrees. A travel distance to the dump
truck 60 is set at the above distance L2. The operator operates the
steering to turn and move the wheel loader 1 for the travel
distance L2. When the wheel loader 1 reaches a side of the dump
truck 60, the operator stops the wheel loader 1 by a brake
operation.
4. End of Loaded State to Loading
[0069] As shown in FIG. 5(E), the operator moves the bucket 31 to
the loading position to load the sand and soil from the bucket 31
onto the vessel 61.
5. Unloaded Reverse Travel to Unloaded Stop
[0070] After the completion of the loading, the operator reverses
the wheel loader 1 in the unloaded state as shown in FIG. 5(F). The
operator operates the steering while reversing the wheel loader 1
so that the wheel loader 1 in the unloaded state is reversed for
the distance L2 and stopped. A position where the wheel loader 1 in
the unloaded state is stopped is the same as the start position
(the unloaded stop position) as shown in FIG. 5(G).
[0071] The operator repeats the above processes to move the wheel
loader 1 along a substantially V-shaped locus (V-shape
operation).
Semi-Automatic Control
[0072] For excavation as shown in FIG. 5(B) in the V-shape
operation, a control allowing the bucket 31 to move in conjunction
with the movement of boom 32 has been employed. Therefore, it is
not necessary for the operator to operate the boom lever 41 and the
bucket lever 42 to move the bucket 31 and the boom 32 during
excavation.
[0073] Typically, the processes other than excavation have required
a manual operation by the operator. In contrast, in the exemplary
embodiment, when the semi-auto mode selection signal set by the
semi-auto mode selecting unit 431 is ON, the working equipment
controller 10 enables an automatic control of the working equipment
3 in the processes other than excavation (e.g., a process where the
wheel loader 1 is to be driven). In the exemplary embodiment, when
the automatic control of the working equipment 3 is enabled, a
semi-automatic control accepting a manual operation of the boom
lever 41 and the bucket lever 42 by the operator is also
enabled.
[0074] Specifically, the semi-automatic control is performed during
the loaded reverse travel of FIG. 5(C), the loaded forward travel
of FIG. 5(D) and the unloaded reverse travel of FIG. 5(F).
[0075] Description will be made on a process of the semi-automatic
control performed by the working equipment controller 10.
[0076] When the process is started in response to an ON-operation
by an engine key, the working equipment controller 10 first
initializes lever operation commands (i.e., a boom lever operation
command: cmd_bm and a bucket lever operation command: cmd_bk) to
"0", and initializes a variable sL representing a start-time
distance for a loaded forward travel control and an unloaded
reverse travel control to "0", as shown in FIG. 6 (Step S1).
[0077] Next, the working equipment controller 10 determines whether
or not the semi-auto mode selection signal outputted from the
semi-auto mode selecting unit 431 indicates that the semi-auto
loading mode is "ON" (Step S2). When the semi-auto loading mode is
"OFF", the determination result by the working equipment controller
10 is "NO" in Step S2. The working equipment controller 10 then
outputs the indicator command to the monitor 43 so that an
indicator indicating that the semi-auto loading mode is on (if any)
disappears from the monitor 43 (Step S3). The working equipment
controller 10 repeats Steps S1 to S3 until the semi-auto loading
mode is turned "ON".
[0078] When the semi-auto loading mode is "ON", the determination
result by the working equipment controller 10 is YES in Step S2.
The working equipment controller 10 then outputs the indicator
command to the monitor 43 so that the monitor 43 displays the
indicator indicating that the semi-auto loading mode is on (Step
S4).
Operating State Detecting Process
[0079] The load determining unit 111 determines whether the wheel
loader 1 is in the loaded state or the unloaded state based on a
boom-bottom pressure sensor signal outputted from the boom-bottom
pressure sensor 46. The forward/reverse travel determining unit 112
determines whether the wheel loader 1 is in the forward traveling
state or the reverse traveling state based on the FR information
outputted from the transmission controller 48. Based on the above
pieces of information, the operating state detecting unit 110 can
detect that the wheel loader 1 is in the loaded reverse traveling
state, the loaded forward traveling state or the unloaded reverse
traveling state.
Loaded Reverse Travel Detection
[0080] The operating state detecting unit 110 of the working
equipment controller 10 determines whether or not a loaded reverse
travel detection is turned ON from OFF (Step S5). When it is
detected that the loaded reverse travel detection is turned ON from
OFF, the determination result by the working equipment controller
10 is "YES" in Step S5. In this case, a variable STAGE representing
an operation stage is set at "2", a variable L representing a
travel distance is set at a default value "0", and a variable sp_bm
(a boom angle) and a variable sp_bk (a bucket cylinder length)
representing the start position of the working equipment are each
set at a value corresponding to the current position (Step S6). In
Step S6, the working equipment controller 10 sets sp_bm at the
current boom angle based on a detection value of the boom angle
sensor 44 and sp_bk at the current bucket cylinder length based on
a detection value of the bucket angle sensor 45.
Loaded Forward Travel Detection
[0081] When the determination result is "NO" in Step S5, the
operating state detecting unit 110 of the working equipment
controller 10 determines whether or not a loaded forward travel
detection is turned ON from OFF (Step S7). When the determination
result is "YES" in Step S7 (it is detected that the loaded forward
travel detection is turned ON), the working equipment controller 10
sets the variable STAGE representing the operation stage at "3",
the variable L representing the travel distance at the default
value "0", sp_bm at the current boom angle, and sp_bk at the
current bucket cylinder length (Step S8).
Unloaded Reverse Travel Detection
[0082] When the determination result is "NO" in Step S7, the
operating state detecting unit 110 of the working equipment
controller 10 determines whether or not an unloaded reverse travel
detection is turned ON from OFF (Step S9). When the determination
result is "YES" in Step S9 (it is detected that the unloaded
reverse travel detection is turned ON), the working equipment
controller 10 sets the variable STAGE representing the operation
stage at "4", the variable L representing the travel distance at
the default value "0", sp_bm at the current boom angle, and sp_bk
at the current bucket cylinder length (Step S10).
Termination Condition Determination
[0083] After the variables are initialized in Steps S6, S8, S10 or
when the determination result is NO in Step S9, the working
equipment controller 10 determines whether or not termination
conditions are satisfied (Step S11).
[0084] Specifically, the termination conditions to be satisfied
include the following six conditions 1 to 6.
[0085] A termination condition 1 is satisfied when a semi-auto mode
is disabled in accordance with the output from the semi-auto mode
selecting unit 431 of the monitor 43.
[0086] A termination condition 2 is satisfied when the operating
state detecting unit 110 detects either an unloaded forward travel
state or an excavation state. The unloaded forward traveling state
may be determined based on the signal from the boom-bottom pressure
sensor and the FR information, and the excavation state may be
determined based on the signal from, for instance, boom-bottom
pressure sensor, the boom angle and the bucket cylinder length.
[0087] A termination condition 3 is satisfied when a lever gear
position is F3 (third forward speed) or greater. The lever gear
position to be selected is F2 or less when the wheel loader 1 is in
the V-shape operation. Therefore, in the case where the lever gear
position is F3, the wheel loader 1 is supposed not to work but
travel.
[0088] A termination condition 4 is satisfied when the working
equipment 3 is locked. The wheel loader 1 is provided with a lock
button to prevent the working equipment 3 from moving during
travel. Therefore, in the case where the operator operates the lock
button, the wheel loader 1 is determined not to work but to
travel.
[0089] A termination condition 5 is satisfied when a failure mode
effect analysis (FMEA) indicates that the sensor(s) and/or the
solenoid proportional pressure control valve(s) (EPC valves) 24 to
27 should have a malfunction requiring termination of the semi-auto
mode.
[0090] A termination condition 6 is satisfied when the engine
operating state inputted from the engine controller 47 indicates
that the engine is stopped.
[0091] When any one of the termination conditions 1 to 6 is
satisfied, the determination result by the working equipment
controller 10 is YES in Step S11. In this case, the working
equipment controller 10 sets the variable STAGE at "1" meaning a
stand-by state. Further, when any one of the conditions other than
the termination condition 2 is satisfied, the working equipment
controller 10 outputs the buzzer command to the monitor 43 to emit
an abnormal termination beep (Step S13). The working equipment
controller 10 then continues the process from Step S1.
Setting Information for Semi-automatic Control
[0092] When the determination result is "NO" (none of the
termination conditions is satisfied) in Step S11, the working
equipment controller 10 checks the value of the variable STAGE
representing the operation stage. The working equipment controller
10 performs: a loaded reverse travel control when STAGE=2; a loaded
forward travel control when STAGE=3; and an unloaded reverse travel
control when STAGE=4, as described later (Step S12).
[0093] It should be noted that these controls are each
independently based on a relationship between the travel distance
of the wheel loader 1 and the target position of the working
equipment 3, which depends on the operating state related to each
of the controls. Specifically, the target position of the working
equipment 3 is a position where the working equipment 3 is to reach
when the wheel loader 1 travels a predetermined distance. Tables 1
and 2 show examples of the target position of the working equipment
3, and FIGS. 7 to 9 show relationships between the travel distance
and the target position determined based on Tables 1 and 2. It
should be noted that parameters defined in Tables 1 and 2 are
stored in the storage 150 of the working equipment controller
10.
[0094] In Table 1, "lifted positioner position" and "lowered
positioner position" in a column of boom angle mean boom angles
preset by the operator. "Positioner position" in a column of bucket
cylinder length is set at a position where the bucket angle becomes
zero degrees when the boom 32 is lowered to bring the bucket 31
into contact with the ground.
TABLE-US-00001 TABLE 1 Working Equipment Bucket Cylinder Target
Boom Angle Length Loaded Reverse (TP1) Horizontal (0 deg) See Table
2 Loaded Forward (TP2) Lifted Positioner Position See Table 2
Unloaded Reverse (TP3) (Not Operated) Positioner Position Unloaded
Reverse (TP4) Horizontal (0 deg) Positioner Position Unloaded
Reverse (TP5) Lowered Positioner Positioner Position Position
TABLE-US-00002 TABLE 2 Bucket Cylinder Length Boom Angle Bucket
Angle High Lift STD -.alpha.1 .beta.1 A1 B1 0 .beta.2 A2 B2
.alpha.2 .beta.3 A3 B3
Relationship Between Travel Distance and Target Position of Working
Equipment in Loaded Reverse Traveling State
[0095] In the loaded reverse travel control, while the wheel loader
1 is reversed for the predetermined distance L1 from a position at
the time of the completion of excavation, the working equipment 3
is moved to a target position TP1 from the current position thereof
at the time of the completion of excavation, as shown in FIG. 7. In
other words, the boom angle, which changes in proportion to the
travel distance, reaches zero degrees (TP1) when the travel
distance reaches L1 as shown in Table 1. The bucket cylinder length
is set to allow the bucket 31 to be maintained at a lifted position
to prevent the load in the bucket 31 from falling out irrespective
of a change in the boom angle.
[0096] For instance, according to the example of Table 2, the
bucket cylinder length is set to allow the bucket angle to become
.beta.2 when the boom angle reaches zero degrees. According to the
example of Table 2, the bucket cylinder length is set at A2 when
the boom 32 attached to the wheel loader 1 is a high-lift boom, and
is set at B2 when the boom 32 attached to the wheel loader 1 is a
standard boom.
[0097] In the loaded reverse travel control, the operator is
supposed to linearly reverse the wheel loader 1 without turning the
steering, so that the working equipment 3 may be set to
continuously move in proportion to the travel distance.
Relationship between Travel Distance and Target Position of Working
Equipment in Loaded Forward Traveling State
[0098] In the loaded forward travel control, as shown in FIG. 8,
the working equipment 3 is maintained at the position TP1 until the
travel distance of the wheel loader 1 reaches a distance
K1.times.L2 (a first interim distance), and is moved from the
position TP1 to a position TP2 in proportion to the travel distance
while the travel distance is increased from the distance
K1.times.L2 to a distance K2.times.L2 (a second interim
distance).
[0099] The working equipment 3 is maintained at the position TP2
while the travel distance of the wheel loader 1 is increased from
the distance K2.times.L2 to the distance L2. A default value of K1
and a default value of K2 are respectively, for instance, 0.5 and
0.8. However, these distance coefficients may be changed by the
operator or the like.
[0100] TP2 is set so that the boom angle corresponds to the raised
positioner position as shown in Tables 1 and 2. The raised
positioner position is determined by the operator in accordance
with the level of the vessel 61 of the dump truck 6 where a load
such as soil and sand is to be loaded from the wheel loader 1. The
bucket cylinder length is appropriately set so that the bucket 31
is kept at the lifted position to prevent the load in the bucket 31
from falling out irrespective of a change in the boom angle.
[0101] In the loaded forward travel control, the operator is
supposed to turn the steering to direct the wheel loader 1 toward
the dump truck 60 until the travel distance reaches K1.times.L2, so
that the position of the working equipment 3 should preferably be
maintained. In contrast, the working equipment 3 is moved to the
lifted positioner position while the travel distance is increased
from K1.times.L2 to K2.times.L2, and is maintained at the lifted
positioner position while the travel distance is increased from
K2.times.L2 to L2, thereby preventing interference between the
bucket 31 and the vessel 61.
Relationship between Travel Distance and Target Position of Working
Equipment in Unloaded Reverse Traveling State
[0102] In the unloaded reverse travel control, as shown in FIG. 9,
the working equipment 3 is maintained at a position TP3 until the
travel distance of the wheel loader 1 reaches a distance
K3.times.L2 (a third interim distance), and is moved from the
position TP3 to a position TP4 in proportion to the travel distance
while the travel distance is increased from the distance
K3.times.L2 to a distance K4.times.L2 (a fourth interim
distance).
[0103] Further, the working equipment 3 is moved from the position
TP4 to a position TP5 in proportion to the travel distance while
the travel distance of the wheel loader 1 is increased from the
distance K4.times.L2 to the distance L2. A default value of K3 and
a default value of K4 are respectively, for instance, 0.2 and 0.5.
However, these distance coefficients may be changed by the operator
or the like.
[0104] As shown in Table 1, the boom angle is "Not Operated" at
TP3. The boom angle is maintained at the lifted positioner position
until the completion of the loading from the completion of the
loaded forward travel, so that the boom angle is still the lifted
positioner position at TP3 for the unloaded reverse travel control.
The bucket cylinder length is set to allow the bucket angle to
become zero degrees when the bucket 31 is brought into contact with
the ground by lowering the boom 32 (i.e., the positioner
position).
[0105] As shown in Table 1, the boom angle is zero degrees and the
bucket cylinder length is the positioner position at TP4. The boom
angle is the lowered positioner position and the bucket cylinder
length is the positioner position at TP5.
[0106] In the unloaded reverse travel control after loading, the
working equipment 3 is maintained at the lifted positioner position
with the bucket 31 being at the positioner position until the
travel distance of the wheel loader 1 reaches the distance
K3.times.L2, thereby preventing interference between the bucket 31
and the vessel 61. The boom 32 is then moved to a horizontal
position while the travel distance of the wheel loader 1 is
increased from the distance K3.times.L2 to the distance
K4.times.L2. Further, the boom 32 is gradually moved to the lowered
positioner position while the travel distance of the wheel loader 1
is increased from the distance K4.times.L2 to the distance L2 and,
simultaneously, the operator operates the steering to move the
wheel loader 1 to the unloaded stop position (i.e., the original
position).
[0107] Next, the controls to be selected in S12 in FIG. 6 will be
described also with reference to FIGS. 10 to 12.
STAGE=2: Loaded Reverse Travel Control
[0108] In the loaded reverse travel control, as shown in FIG. 10,
the working equipment controller 10 determines whether or not a
travel distance L obtained by the travel distance detecting unit
130 is less than the preset value L1 (Step S21).
Calculation of Current Travel Distance
[0109] When the determination result by the working equipment
controller 10 is "YES" in Step S21, the travel distance detecting
unit 130 calculates the current travel distance L (Step S22). The
current travel distance L is calculated by
.intg.(abs(V)*1000/3600*.DELTA.t). V, which represents a vehicle
speed (km/h), is multiplied by 1000/3600 to be converted to meters
per second (m/s). .DELTA.t represents a program-execution cycle
(sec) for the working equipment controller 10, and may be 0.01
sec.
[0110] When the determination result is "NO" in Step S21 (i.e., the
travel distance has already reached the distance L1), the working
equipment controller 10 skips the calculation of the current travel
distance L in Step S22.
Calculation of Boom Target Position
[0111] After Step S22 or when the determination result is "NO" in
Step S21, the target setting unit 120 of the working equipment
controller 10 calculates a boom target position (Step S23). For the
loaded reverse travel, the angle of the boom 32 is controlled in
proportion to the travel distance as shown in FIG. 7. A boom target
position tp_bm(t) at the travel distance L can thus be calculated
by L/L1*(TP1_bm-sp_bm)+sp_bm. TP1_bm represents a boom angle at the
target position TP1, and sp_bm represents the start position of the
boom 32 set in Step S6. In other words, the boom target position
tp_bm(t) can be obtained by multiplying a ratio of the travel
distance L to the preset distance L1 and a difference between the
target position and start position of the boom 32, and adding the
start position (the default value).
Calculation of Bucket Target Position
[0112] After Step. S23, the target setting unit 120 of the working
equipment controller 10 calculates a bucket target position (Step
S24). The bucket target position can be calculated in the same
manner as the boom target position. In other words, for the loaded
reverse travel, the angle of the boom 32 is controlled in
proportion to the travel distance as described above. Specifically,
as shown in Table 2, the bucket angle is set in accordance with the
boom angle, and the bucket cylinder length is set in accordance
with the bucket angle. The cylinder length of the bucket cylinder
35, which actuates the bucket 31, is thus controlled in accordance
with the angle of the boom 32.
[0113] A bucket target position p_bk(t) at the travel distance L
can thus be calculated by L/L1*(TP1_bk-sp_bk)+sp_bk. TP1_bk
represents a bucket cylinder length at the target position TP1, and
sp_bk represents the start position of the bucket 31 set in Step
S6. In other words, the bucket target position tp_bk(t) can be
obtained by multiplying a ratio of the travel distance L to the
preset distance L1 and a difference between the target position and
start position of the bucket 31, and adding the start position (the
default value). The target setting unit 120 thus sets the bucket
cylinder length (i.e., the bucket target position tp_bk(t) at the
travel distance L) in proportion to the travel distance, the bucket
cylinder length varying from a bucket cylinder length at the start
of the movement in the loaded reverse traveling state to a bucket
cylinder length where the bucket is to reach the tilting position
when the travel distance of the wheel loader reaches the distance
L1. In other words, the target setting unit 120 sets the bucket
cylinder length in accordance with the boom angle to maintain the
bucket 31 at the tilting position.
Calculation of Deviation
[0114] Next, the working equipment controlling unit 140 of the
working equipment controller 10 calculates a deviation between an
actual boom angle detected by the boom angle sensor 44 and the
target position and a deviation between an actual bucket cylinder
length detected based on the detection value of the bucket angle
sensor 45 and the target position (Step S25). Specifically, a boom
target deviation angle .DELTA.bm is calculated by boom target
position tp_bm(t)-actual boom angle BmAngle, and a bucket target
deviation length .DELTA.bk is calculated by bucket target position
tp_bk(t)-actual bucket cylinder length BkLength.
Calculation of Boom Lever Operation Command
[0115] After Step S25, the working equipment controlling unit 140
of the working equipment controller 10 calculates a boom lever
operation command cmd_bm (Step S26). The boom lever operation
command cmd_bm, which specifies the flow rate of the hydraulic oil
in each of the solenoid proportional pressure control valves 26, 27
in a range from -100% to +100%, is calculated by adding an
auto-boom command based on the boom target deviation angle
.DELTA.bm calculated in Step S25 and a boom lever command BmLever
inputted when the operator operates the boom lever 41.
[0116] The auto-boom command is calculated by a function interp
(.DELTA.bm, BmCmdFlow, DeltaBmAngle) for obtaining a target flow
rate corresponding to the boom target deviation angle .DELTA.bm
with reference to a boom flow rate table BmCmdFlow defining a
relationship between the boom deviation angle and the target flow
rate shown in FIG. 14. When the boom lever 41 is manually operated,
the auto-boom command (%) is added with the boom lever command.
[0117] As shown in FIG. 14, when the boom deviation angle is small
(e.g., -2 to 2 degrees), the auto-boom command specifies a small
target flow rate such as approximately -20 to +20%, and thus the
movement speed of the boom 32 becomes slow. In this case, the
operator may operate the boom lever 41 to increase the value of the
target flow rate and, consequently, to increase the movement speed
of the boom 32.
Calculation of Bucket Lever Operation Command
[0118] After Step S26, the working equipment controlling unit 140
of the working equipment controller 10 calculates a bucket lever
operation command cmd_bk (Step S27). The bucket lever operation
command cmd_bk, which specifies the flow rate of the hydraulic oil
in each of the solenoid proportional pressure control valves 24, 25
in a range from -100% to +100%, is calculated by adding an
auto-bucket command based on the bucket target deviation length
.DELTA.bk calculated in Step S25 and a bucket lever command BkLever
inputted when the operator operates the bucket lever 42.
[0119] The auto-bucket command is calculated by a function interp
(.DELTA.bk, BkCmdFlow, DeltaBmLength) for obtaining a target flow
rate corresponding to the bucket target deviation length .DELTA.bk
with reference to a bucket flow rate table BkCmdFlow defining a
relationship between the bucket deviation length and the target
flow rate shown in FIG. 15. When the bucket lever 42 is manually
operated, the auto-bucket command (%) is added with the bucket
lever command. As shown in FIG. 15, when the bucket deviation
length is small (e.g., -20 to 20 mm), the auto-bucket command also
specifies a small target flow rate such as approximately -20 to
+20%, and thus the movement speed of the bucket 31 becomes slow. In
this case, the operator may operate the bucket lever 42 to increase
the value of the target flow rate and, consequently, to increase
the movement speed of the bucket 31.
[0120] The boom lever operation command cmd_bm and the bucket lever
operation command cmd_bk calculated in Steps S26, S27 are inputted
from the working equipment controlling unit 140 to the solenoid
proportional pressure control valves 24 to 26 to control the action
of each of the bucket operation valve 22 and the boom operation
valve 23 so that the bucket cylinder 35 and the boom cylinder 36
actuate the working equipment 3.
[0121] Referring back to FIG. 6, the working equipment controller
10 again performs the process from Step S5 after Step S27. When the
loaded reverse travel still continues, the determination results
are NO (i.e., the loaded reverse travel detection is already ON) in
Step S5, NO in each of Steps S7, S9, NO in Step S11, and "2" in
Step S12. Consequently, the loaded reverse travel control shown in
FIG. 10 is repeated.
[0122] It should be noted that the working equipment 3 is to be
moved to the target position TP1 when the travel distance reaches
L1 as shown in FIG. 7 during the loaded reverse travel, but the
working equipment 3 may reach the target position TP1 before the
travel distance reaches L1 when a value corresponding to the lever
operation by the operator is added. When the working equipment 3
reaches the target position TP1, the deviation calculated in Step
S25 becomes zero, and the working equipment 3 is maintained at the
target position TP1.
[0123] However, when the travel speed is increased much more than
usual by the accelerator operation, which is performed by the
operator as well as the steering operation, a supply flow rate of
the hydraulic oil to the working equipment may fail to meet the
increase in the travel speed and, consequently, the travel distance
may reach the distance L1 before the completion of the movement of
the working equipment 3. In this case, only the working equipment 3
is to be moved after the completion of the travel of the wheel
loader 1.
STAGE=3: Loaded Forward Travel Control
[0124] FIG. 11 is a process flow of the loaded forward travel
control. A part of the process shown in FIG. 11 is identical to
that of the process of the loaded reverse travel control shown in
FIG. 10, and thus description thereof is simplified.
[0125] The working equipment controller 10 determines whether or
not the travel distance L obtained by the travel distance detecting
unit 130 is less than the preset value L2 (Step S31).
[0126] When the determination result by the working equipment
controller 10 is "YES" in Step S31, the travel distance detecting
unit 130 calculates the current travel distance in the same manner
as in Step S22 (Step S32).
[0127] When the determination result is "NO" in Step S31 (i.e., the
travel distance has already reached the distance L2), the working
equipment controller 10 skips the calculation of the current travel
distance L in Step S32.
[0128] After Step S32 or when the determination result is "NO" in
Step S31, the working equipment controller 10 determines whether or
not the travel distance L is equal to or more than K1.times.L2 but
less than K2.times.L2 (Step S33). When the travel distance L is
less than K1.times.L2, the determination result by the working
equipment controller 10 is NO in Step S33. For instance, when a
distance coefficient K1 is 0.5 and the travel distance L1 does not
reach a half of the preset distance L2, the determination result by
the working equipment controller 10 is NO in Step S33.
[0129] When the determination result is NO in Step S33, the target
setting unit 120 of the working equipment controller 10 assigns the
actual boom angle BmAngle to the boom target position tp_bm(t)
(Step S34), and assigns the actual bucket cylinder length BkLength
to the bucket target position tp_bk(t) (Step S35). In other words,
the target setting unit 120 sets each of the boom target position
and the bucket target position at the current position.
[0130] Therefore, in a deviation calculating process (Step S39),
which is identical to the process of Step S25, the boom target
deviation angle .DELTA.bm calculated by boom target position
tp_bm(t)-actual boom angle BmAngle and the bucket target deviation
length .DELTA.bk calculated by bucket target position
tp_bk(t)-actual bucket cylinder length BkLength b each become
zero.
[0131] As a result, in a boom lever operation command calculating
process (Step S40) and a bucket lever operation command calculating
process (Step S41), which are respectively identical to the
processes of Steps S26, S27, the auto-boom command and the
auto-bucket command each specify a flow rate of 0% in accordance
with the deviation of zero. A flow rate corresponding to the boom
lever command or the bucket lever command is thus calculated as the
operation command only when the boom lever 41 or bucket lever 42 is
manually operated.
[0132] Consequently, when the travel distance L of the wheel loader
1 is less than K1.times.L2, the working equipment 3 is maintained
at TP1 according to the automatic control by the working equipment
controller 10, but may be moved in accordance with a manual
operation by the operator.
[0133] When the determination result is "YES" in Step S33 (i.e.,
the travel distance L is K1.times.L2 or more but less than
K2.times.L2), the working equipment controller 10 determines
whether or not the start-time distance sL is set at K1.times.L2
(Step S36). When the determination result is "NO" in Step S36, the
working equipment controller 10 sets: the start-time distance sL at
K1.times.L2 (i.e., the first interim distance); sp_bm at the
current boom angle (i.e., a boom angle at the time when the first
interim distance is reached); and sp_bk at the current bucket
cylinder length (i.e., a bucket cylinder length when the first
interim distance is reached) (Step S36A). In other words, when
performing the determining process of Step S36 for the first time
in the process flow of the loaded forward travel control shown in
FIG. 11, the working equipment controller 10 sets the start-time
distance sL at K1.times.L2 in Step S36A. Otherwise, since sL has
already been set at K1.times.L2, the determination result is "NO"
in Step S36, and the flow proceeds to Step S37. The working
equipment controller 10 thus performs the process of Step S36A only
once. As shown in FIG. 8, when the travel distance L is
=K1.times.L2, the working equipment 3 is normally maintained at the
target position TP1, but may not be positioned at TP1 in the case
where the operator manually operates the working equipment 3.
Accordingly, in Step S36A, sp_bm and sp_bk are respectively set at
the boom angle and the bucket cylinder length at the time when the
travel distance L reaches the first interim distance
(K1.times.L2).
[0134] Subsequently, the target setting unit 120 of the working
equipment controller 10 calculates the boom target position as in
Step S23 (Step S37). During the loaded forward travel from a spot
of K1.times.L2 to a spot of K2.times.L2, the angle of the boom 32
is controlled in proportion to the travel distance as shown in FIG.
8. The boom target position tp_bm(t) at the travel distance L can
thus be calculated by (L-sL)/(L2*(K2-K1))*(TP2_bm-sp_bm)+sp_bm.
TP2_bm represents the boom angle at the target position TP2, and
sp_bm represents the start position for a lifting control of the
boom 32 determined in Step S36A. L-sL represents a travel distance
from the spot of K1.times.L2 (the first interim distance), and
(L2*(K2-K1)) represents a distance from the spot of K1.times.L2 to
the spot of K2.times.L2 (the second interim distance). In other
words, the boom target position tp_bm(t) can be obtained by
multiplying a ratio (L-sL) of the travel distance from the spot of
K1.times.L2 relative to the distance (L2*(K2-K1)) defined from the
spot of K1.times.L2 to the spot of K2.times.L2 and a difference
(TP2_bm-sp_bm) between the target position and start position of
the boom 32, and adding the start position (sp_bm) (the default
value). Consequently, in the case where the boom angle sp_bm at the
time when the travel distance L is =K1.times.L2 is smaller than the
target speed TP1, a variation of the boom angle relative to the
travel distance becomes large as compared with the variation shown
by the graph of FIG. 8. In contrast, in the case where the boom
angle sp_bm at the time when the travel distance L is =K1.times.L2
is larger than the target speed TP1, a variation of the boom angle
relative to the travel distance becomes small as compared with the
variation shown by the graph of FIG. 8.
[0135] Subsequently, the target setting unit 120 of the working
equipment controller 10 calculates the bucket target position as in
Step S24 (Step S38). Specifically, the bucket target position
tp_bk(t) at the travel distance L can be calculated by
(L-sL)/(L2*(K2-K1))*(TP2_bk-sp_bk)+sp_bk.
[0136] In other words, when the travel distance is the first
interim distance or more but less than the second interim distance,
the target setting unit 120 sets the boom angle (i.e., a boom
target position for the loaded forward traveling state) in
proportion to the travel distance, the boom angle varying from a
boom angle at the time when the travel distance reaches the first
interim distance to a boom angle where the boom 32 is to reach the
preset lifted positioner position when the travel distance reaches
the second interim distance. Similarly, the target setting unit 120
sets the bucket cylinder length (i.e., a bucket target position for
the loaded forward traveling state) in proportion to the travel
distance, the bucket cylinder length varying from a bucket cylinder
length at the time when the travel distance reaches the first
interim distance to a bucket cylinder length where the bucket 31 is
to reach the tilting position when the travel distance reaches the
second interim distance. In other words, the target setting unit
120 sets the bucket cylinder length in accordance with the boom
angle to maintain the bucket 31 at the tilting position.
[0137] After Step S35 or Step S38, the working equipment
controlling unit 140 of the working equipment controller 10
calculates a deviation between each of the actual boom angle and
bucket cylinder length and the target position as in Step S25 (Step
S39).
[0138] Subsequently, after Step S39, the working equipment
controlling unit 140 of the working equipment controller 10
calculates the boom lever operation command cmd_bm (Step S40) and
the bucket lever operation command cmd_bk (Step S41). The process
of Step S40 and the process of Step S41 are respectively identical
to those of Step S26, Step S27, and thus description thereof is
omitted.
[0139] The boom lever operation command cmd_bm and the bucket lever
operation command cmd_bk calculated in Steps S40, S41 are inputted
from the working equipment controlling unit 140 to the solenoid
proportional pressure control valves 24 to 26 to control the action
of each of the bucket operation valve 22 and the boom operation
valve 23 so that the bucket cylinder 35 and the boom cylinder 36
actuate the working equipment 3.
[0140] Referring back to FIG. 6, the working equipment controller
10 again performs the process from Step S5 after Step S41. When the
loaded reverse travel still continues, the determination results
are NO (i.e., the loaded reverse travel detection is already ON) in
Step S7, NO in each of Steps S5, S9, NO in Step S11, and "3" in
Step S12. Consequently, the loaded reverse travel control shown in
FIG. 11 is repeated.
[0141] It should be noted that, in the loaded forward travel
control, the working equipment 3 is controlled to reach the target
position TP2 when the travel distance of the wheel loader 1 reaches
K2.times.L2 as shown in FIG. 8. After the working equipment 3
reaches the target position TP2, L is determined to be K2.times.L2
or more in Step S33 (the determination result is "NO"), so that the
processes of Steps S34, S35 are performed and the deviation is
determined to be "0" in Step S39 as described above. The working
equipment 3 is thus maintained at the target position TP2. When the
operator manually operates the working equipment 3, the working
equipment 3 may be moved to and maintained at any position in
accordance with the manual operation.
STAGE=4: Unloaded Reverse Travel Control
[0142] FIGS. 12 and 13 show a process flow of the unloaded reverse
travel control. A part of the process shown in FIGS. 12 and 13 is
identical to that of the process shown in FIGS. 10 and 11, and thus
description thereof is simplified.
[0143] The working equipment controller 10 checks whether or not
the wheel loader 1 is "Unloaded" by comparison between the
boom-bottom pressure and a preset value A(kg) (Step S51). When the
boom-bottom pressure is less than the preset value A and,
consequently, the determination result is NO (the loaded state) in
Step S51, the working equipment controller 10 completes the
unloaded reverse travel control and the flow returns to the process
shown in FIG. 6. This results in preventing the boom 32 from being
controlled to be lowered in the loaded state.
[0144] When the determination result is YES in Step S51, the
working equipment controller 10 determines whether or not the
travel distance L obtained by the travel distance detecting unit
130 is less than the preset value L2 (Step S52).
[0145] When the determination result by the working equipment
controller 10 is "YES" in Step S52, the travel distance detecting
unit 130 calculates the current travel distance L in the same
manner as in Steps S22, S32 (Step S53).
[0146] When the determination result is "NO" in Step S52 (i.e., the
travel distance has already reached the distance L2), the working
equipment controller 10 skips the calculation of the current travel
distance L in Step S53.
[0147] After Step S52 or when the determination result is "NO" in
Step S52, the working equipment controller 10 determines whether or
not the travel distance L is less than K3.times.L2 (the third
interim position) (Step S54).
[0148] For instance, when K3 is 0.2 and the travel distance L does
not reach 20% of the preset distance L2, the determination result
by the working equipment controller 10 is YES in Step S54.
[0149] When the determination result is YES in Step S54, the target
setting unit 120 of the working equipment controller 10 determines
whether or not a deviation length between an absolute value of the
actual bucket cylinder length BkLength and a bucket target position
TP3_bk exceeds a preset value (e.g., 10 mm) (Step S55). As shown in
Table 1, at the working equipment target TP3 for the unloaded
reverse travel control, the boom 32 is not operated and only the
bucket 31 is moved to the positioner position. The bucket 31 is
positioned not at the positioner position but at the loading
position immediately after the completion of loading, the
determination result by the working equipment controller 10 is YES
in Step S55.
[0150] When the determination result is YES in Step S55, the target
setting unit 120 of the working equipment controller 10 calculates
the boom target position (Step S56) and calculates the bucket
target position (Step S57).
[0151] Since the boom 32 is not operated, the target setting unit
120 assigns the actual boom angle BmAngle to the boom target
position tp_bm(t) in Step S56 (Step S56).
[0152] Further, the bucket target position is calculated by
tp_bk(t)=L/(K3*L2)*(TP3 bk-sp_bk)+sp_bk as in Step S24 to move the
bucket 31 from the loading position to the positioner position
while the wheel loader 1 is moved to a spot of K3.times.L2 (Step
S57). In other words, the target setting unit 120 sets the bucket
cylinder length in proportion to the travel distance, the bucket
cylinder length varying from a bucket cylinder length at the start
of the movement in the unloaded reverse traveling state to a bucket
cylinder length where the bucket 31 is to reach a preset initial
position (the positioner position in the exemplary embodiment) when
the travel distance of the wheel loader 1 reaches the third interim
distance.
[0153] When the target setting unit 120 of the working equipment
controller 10 determines that the deviation length between the
absolute value of the actual bucket cylinder length BkLength and
the bucket target position TP3 bk falls below 10 mm, the
determination result is NO in Step S55. In this case, the bucket 31
is supposed to almost reach the positioner position, so that it is
not necessary for the working equipment controller 10 to further
move the bucket 31. Therefore, the target setting unit 120 assigns
the actual boom angle BmAngle to the boomtarget position tp_bm(t)
(Step S58) and assigns the actual bucket cylinder length BkLength
to the bucket target position tp_bk(t) (Step S59) as in Steps S34,
S35.
[0154] When the travel distance L does not reach K3.times.L2, the
determination result by the working equipment controller 10 is NO
in each of Steps S60, S64 as described later. The working equipment
controller 10 thus performs the deviation calculating process (Step
S68), the boom lever operation command calculating process (Step
S69) and the bucket lever operation command calculating process
(Step S70) as in Steps S25 to S27 and Steps S39 to S41.
[0155] Consequently, until the travel distance L reaches
K3.times.L2, the boom 32 is maintained at the lifted positioner
position, and the bucket 31 is moved to and maintained at the
positioner position.
[0156] When the travel distance L of the wheel loader 1 reaches
K3.times.L2 (the third interim distance) or more but less than
K4.times.L2 (the fourth interim position), the determination result
by the working equipment controller 10 turns NO in each of Steps
S54, S64 and YES in Step S60.
[0157] When the determination result is "YES" in Step S60, the
working equipment controller 10 determines whether or not the
start-time distance sL is set at K3.times.L2 (Step S61). When the
determination result is "NO" in Step S61, the working equipment
controller 10 sets the start-time distance sL at K3.times.L2, sp_bm
at the current boom angle, and sp_bk at the current bucket cylinder
length (Step S61A). The working equipment controller 10 thus
performs the process of Step S61A only once in the same manner as
Step S36A.
[0158] Subsequently, the working equipment controller 10 calculates
the boom target position as in Step S37 (Step S62). During the
unloaded reverse travel from the spot of K3.times.L2 to a spot of
K4.times.L2, the angle of the boom 32 is controlled to be reduced
in proportion to the travel distance as shown in FIG. 9. The boom
target position tp_bm(t) at the travel distance L can thus be
calculated by (L-sL)/(L2*(K4-K3))*(TP4_bm-sp_bm)+sp_bm. TP4 bm
represents a boom angle at the target position TP4, which is set at
zero degrees (horizontal). sp_bm represents a start position for
the control of reducing the angle of the boom 32 set in Step S61A.
The boom angle is maintained at the lifted positioner position
until L reaches K3.times.L2 unless the operator manually operates
the boom 32, so that sp_bm is set at the lifted positioner
position. L-sL represents a travel distance from the spot of
K3.times.L2, and (L2*(K4-K3)) represents a distance from the spot
of K3.times.L2 to the spot of K4.times.L2. In other words, the boom
target position tp_bm(t) can be obtained by multiplying a ratio of
the travel distance from the spot of K3.times.L2 relative to a
distance from the spot of K3.times.L2 to the spot of K4.times.L2
and a difference between the target position and control start
position of the boom 32, and adding the start position (the default
value). The target setting unit 120 thus sets the boom angle (i.e.,
a target position of the boom 32 for the unloaded reverse traveling
state) in proportion to the travel distance, the boom angle varying
from a boom angle at the time when the travel distance reaches the
third interim distance to a boom angle at which the boom 32 is to
get horizontal when the travel distance reaches the fourth interim
distance.
[0159] Subsequently, the working equipment controller 10 calculates
the bucket target position as in Step S38 (Step S63). Specifically,
the bucket target position tp bk(t) at the travel distance L can be
calculated by (L-sL)/(L2*(K4-K3))*(TP4 bk-sp_bk)+sp_bk. The target
setting unit 120 thus sets a bucket cylinder length where the
bucket 31 is maintained at the preset initial position (the
positioner position in the exemplary embodiment), the bucket
cylinder length defining the target position of the bucket 31 for
the unloaded reverse traveling state.
[0160] After Step S63, the working equipment controller 10 performs
the above processes of Steps S68 to S70.
[0161] When the travel distance L of the wheel loader 1 reaches
K4.times.L2 (the fourth interim distance) or more, the
determination result by the working equipment controller 10 turns
NO in each of Steps S54, S60 and YES in Step S64.
[0162] When the determination result is "YES" in Step S64, the
working equipment controller 10 determines whether or not the
start-time distance sL is set at K4.times.L2 as in Step S61 (Step
S65). When the determination result is "NO" in Step S65, the
working equipment controller 10 sets the start-time distance sL at
K4.times.L2, sp_bm at the current boom angle, and sp_bk at the
current bucket cylinder length (Step S65A). The working equipment
controller 10 thus performs the process of Step S65A only once in
the same manner as Steps S36A, S61A.
[0163] Subsequently, the working equipment controller 10 calculates
the boom target position as in Step S62 (Step S66). During the
unloaded reverse travel from the spot of K4.times.L2 to a spot of
L2, the angle of the boom 32 is controlled to be moderately reduced
in proportion to the travel distance as shown in FIG. 9. The boom
target position tp_bm(t) at the travel distance L can thus be
calculated by (L-sL)/(L2*(1-K4))*(TP5_bm-sp_bm)+sp_bm. TP5 bm
represents a boom angle at the target position TP5, which is set at
a lowered positioner position settable by the operator. sp_bm
represents the control start position of the boom 32 set in Step
S65A, and is the target value TP4 as long as the automatic control
is enabled. L-sL represents a travel distance from the spot of
K4.times.L2, and (L2*(1-K4)) represents a distance from the spot of
K4.times.L2 to the spot of L2. In other words, the boom target
position tp_bm(t) can be obtained by multiplying a ratio of the
travel distance from the spot of K4.times.L2 relative to a distance
from the spot of K4.times.L2 to the spot of L2 and a difference
between the target position and control start position of the boom
32, and adding the start position (the default value). The target
setting unit 120 thus sets the boom angle (i.e., a target position
of the boom 32 for the unloaded reverse traveling state) in
proportion to the travel distance, the boom angle varying from a
boom angle at the time when the travel distance reaches the fourth
interim distance to a boom angle at which the boom 32 is to get
horizontal when the travel distance reaches the distance L2.
[0164] Subsequently, the working equipment controller 10 calculates
the bucket target position as in Step S63 (Step S67). Specifically,
the bucket target position tp_bm(t) at the travel distance L can be
calculated by (L-sL)/(L2*(1-K4))*(TP5_bk-sp_bk)+sp_bk. The target
setting unit 120 thus sets a bucket cylinder length where the
bucket 31 is maintained at the preset initial position (the
positioner position in the exemplary embodiment), the bucket
cylinder length defining the target position of the bucket 31 for
the unloaded reverse traveling state.
[0165] After Step S67, the working equipment controller 10 performs
the above processes of Steps S68 to S70.
[0166] The V-shape operation can be repeated by repeating the above
control process.
Advantage(s) of Exemplary Embodiment(s)
[0167] In the above exemplary embodiment, the bucket 31 and the
boom 32 of the working equipment 3 are automatically moved to the
respective target positions in accordance with the travel distance
of the wheel loader 1 under the control by the working equipment
controller 10 during the loaded reverse travel, the loaded forward
travel and the unloaded reverse travel. The exemplary embodiment
thus eliminates a necessity for an operator to simultaneously
operate the boom lever 41 and the bucket lever 42 along with the
steering and/or the accelerator. The operator is thus merely
required to mainly operate the steering, accelerator and brake.
Consequently, even an inexperienced operator can easily operate the
wheel loader 1.
[0168] Further, the working equipment 3 is automatically moved to
an appropriate position during the travel of the wheel loader 1,
which results in an improved operating efficiency and a fuel-saving
driving as compared with an instance where the working equipment 3
is moved after the travel of the wheel loader 1.
[0169] In the loaded reverse travel, the loaded forward travel and
the unloaded reverse travel, the working equipment controller 10
performs the semi-automatic control, so that an operator can
manually operate the boom lever 41 and the bucket lever 42 to
interrupt the automatic control of the working equipment 3. The
intention of the operator can be reflected in the movement of the
working equipment 3. For instance, the working equipment 3 may be
moved at a high speed to improve the operability.
[0170] Incidentally, it should be understood that the scope of the
invention is not limited to the above-described exemplary
embodiment(s), but includes modifications and improvements
compatible with the invention.
[0171] In the exemplary embodiment, the semi-automatic control
according to the invention is performed during operations including
the loaded reverse travel, the loaded forward travel and the
unloaded reverse travel, but may be performed only during one or
two of these operations.
[0172] The relationship between the travel distance of the wheel
loader 1 and the target position of the working equipment 3 for
each of the operations may be different from those of FIGS. 7 to 9.
For instance, in the loaded reverse travel control, the working
equipment 3 may be moved to the target position TP1 when the wheel
loader 1 reaches not the travel distance L1 but an interim spot
therebefore. In the loaded forward travel control, the boom 32 may
be moderately lifted to a new target position defined between the
target positions TP1 and TP2 without being maintained until the
travel distance reaches the first interim distance (K1.times.L2).
Further, in the unloaded reverse travel control, the working
equipment 3 may be moved to the lowered positioner position when
the travel distance reaches the fourth interim distance
(K4.times.L2) and then be maintained at the position TP5.
[0173] Further, an operator may set the relationship between the
travel distance of the wheel loader 1 and the target position of
the working equipment 3 for each of the operations. For instance,
an operator may change the relationship between the travel distance
of the wheel loader 1 and the target position of the working
equipment 3 for each of the operations by changing the values of
the distance coefficients K1 to K4 displayed on the monitor 43 and
storing the changed values in the storage 150.
[0174] Further, since the semi-automatic control according to the
invention accepts a manual operation of the boom lever 41 and the
bucket lever 42, an operator may change the relationship between
the travel distance of the wheel loader 1 and the target position
of the working equipment 3 for each of the operations by storing a
distance where the working equipment 3 is moved to the target
position by the manual operation in the storage 150 and changing,
for instance, the values of the distance coefficients K1 to K4 in
accordance with the distance stored in the storage 150. For
instance, in the loaded forward travel control, K1 is 0.5 and thus
the working equipment 3 is maintained at the target position TP1
until the wheel loader 1 reaches not L2 but an interim spot
therebefore. However, in the case where an operator operates the
boom lever 41 to move the working equipment 3 toward the target
position TP2 before the wheel loader 1 reaches the interim spot
(e.g., at a spot of 0.4.times.L2), the distance coefficient K1 may
be changed to 0.4. In this manner, the preference of operation of
each operator can be reflected in the semi-automatic control of the
working equipment 3.
[0175] It should be noted that the exemplary embodiment employs the
semi-automatic control accepting interruption of a manual operation
of the boom lever 41 and/or the bucket lever 42 in the control of
the working equipment 3, but the control of the working equipment 3
may be a fully automatic control inhibiting interruption of a
manual operation in the control of the working equipment 3.
Further, the semi-automatic control and the automatic control may
be selectable. Especially, in the case where an inexperienced
operator operates, interruption of the manual operation may lead to
a reduction in operating efficiency. In such a case, a mode
inhibiting interruption of the manual operation may be
selected.
[0176] Further, the target travel distance and actual travel
distance of the wheel loader 1 and the target position and actual
position of the working equipment 3 may be displayed on the monitor
43 during the semi-automatic control to assist an operator.
EXPLANATION OF CODE(S)
[0177] 1 . . . wheel loader, 3 . . . working equipment, 10 . . .
working equipment controller, 21 . . . hydraulic pump, 22 . . .
bucket operation valve, 23 . . . boom operation valve, 24 to 27 . .
. solenoid proportional pressure control valve, 31 . . . bucket, 32
. . . boom, 35 . . . bucket cylinder, 36 . . . boom cylinder, 41 .
. . boom lever, 42 . . . bucket lever, 43 . . . monitor, 44 . . .
boom angle sensor, 45 . . . bucket angle sensor, 46 . . .
boom-bottom pressure sensor, 47 . . . engine controller, 48 . . .
transmission controller, 49 . . . FR lever, 50 . . . vehicle speed
sensor, 60 . . . dump truck, 61 . . . vessel, 110 . . . operating
state detecting unit, 111 . . . load determining unit, 112 . . .
forward/reverse travel determining unit, 120 . . . target setting
unit, 130 . . . travel distance detecting unit, 140 . . . working
equipment controlling unit, 150 . . . storage, 431 . . . semi-auto
mode selecting unit, 432 . . . approach length setting unit, 435 .
. . indicator, 436 . . . buzzer
* * * * *