U.S. patent application number 16/059438 was filed with the patent office on 2018-12-06 for shovel and control method thereof.
The applicant listed for this patent is SUMITOMO(S.H.I.) CONSTRUCTION MACHINERY CO., LTD.. Invention is credited to Hiroyuki TSUKAMOTO.
Application Number | 20180347151 16/059438 |
Document ID | / |
Family ID | 52706065 |
Filed Date | 2018-12-06 |
United States Patent
Application |
20180347151 |
Kind Code |
A1 |
TSUKAMOTO; Hiroyuki |
December 6, 2018 |
SHOVEL AND CONTROL METHOD THEREOF
Abstract
A shovel includes a lower running body and an upper turning body
that is turnably provided on the lower running body. An engine is
mounted on the upper turning body. A hydraulic pump is driven by
the engine to discharge an operating oil. A hydraulic actuator is
mounted on the upper turning body. A control device controls
operations of the shovel. An entering object detection device
detects a position of an entering object in a monitoring area of
said shovel and outputs a detection signal indicating the detection
position of said entering object. The control device supplies,
after a determination of an entry of the entering object into the
monitoring area, the operating oil from the hydraulic pump to the
hydraulic actuator.
Inventors: |
TSUKAMOTO; Hiroyuki; (Chiba,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SUMITOMO(S.H.I.) CONSTRUCTION MACHINERY CO., LTD. |
Tokyo |
|
JP |
|
|
Family ID: |
52706065 |
Appl. No.: |
16/059438 |
Filed: |
August 9, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14662435 |
Mar 19, 2015 |
10072395 |
|
|
16059438 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E02F 9/2285 20130101;
E02F 9/123 20130101; E02F 3/435 20130101; F16P 3/141 20130101; E02F
9/2282 20130101; E02F 9/2292 20130101; E02F 9/262 20130101; F16P
3/142 20130101; E02F 9/2033 20130101; E02F 9/128 20130101; F16P
3/147 20130101; E02F 9/2296 20130101 |
International
Class: |
E02F 9/20 20060101
E02F009/20; E02F 9/22 20060101 E02F009/22; E02F 9/12 20060101
E02F009/12; F16P 3/14 20060101 F16P003/14; E02F 3/43 20060101
E02F003/43; E02F 9/26 20060101 E02F009/26 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 27, 2014 |
JP |
2014-067213 |
Claims
1. A shovel, comprising: a lower running body; an upper turning
body that is turnably provided on the lower running body; an engine
that is mounted on said upper turning body; a hydraulic pump that
is driven by the engine to discharge an operating oil; a hydraulic
actuator that is mounted on said upper turning body; a flow control
valve that supplies a pressurized operating oil to the hydraulic
actuator depending on an amount of operation of an operation
device; a control device that controls operations of said shovel;
an object detection device that detects a position of an object in
a monitoring area of said shovel; a first solenoid proportional
valve that is provided in a pilot line connected to a left pilot
port of the flow control valve, and receives a signal from the
control device; and a second solenoid proportional valve that is
provided in a pilot line connected to a right pilot port of the
flow control valve, and receives a signal from the control
device.
2. The shovel as claimed in claim 1, wherein the control device
controls the first solenoid proportional valve and/or the second
solenoid proportional valve depending on a predetermined signal
pattern preliminarily stored in an internal memory.
3. The shovel as claimed in claim 1, further comprising: an
attachment mounted on the upper turning body; and an orientation
detector provided at the attachment, wherein the control device
receives a detection signal from the orientation detector.
4. The shovel as claimed in claim 1, wherein the control device
controls the first solenoid proportional valve and/or the second
solenoid proportional valve based on a positional relationship
between the shovel and the object.
5. The shovel as claimed in claim 1, wherein, the operation device
is an arm lever.
6. The shovel as claimed in claim 1, wherein the control device
controls the first solenoid proportional valve and/or the second
solenoid proportional valve irrelevant to a change of the amount of
operation of the operation device.
7. The shovel as claimed in claim 1, wherein the control device
controls the first solenoid proportional valve and/or the second
solenoid proportional valve depending on a degree of risk of
contact between the shovel and the object.
8. The shovel as claimed in claim 1, wherein the control device
causes an alarm lamp to turn on or to blink.
9. The shovel as claimed in claim 1, wherein the control device
sounds an alarm buzzer upon detecting that the object is in the
predetermined monitoring area.
10. The shovel as claimed in claim 1, wherein the control device
changes a type of an alarm, upon detecting that the object is in
the predetermined monitoring area, depending on an area where the
object is detected.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a continuation of patent
application Ser. No. 14/662,435 filed on Mar. 19, 2015, which is
based on and claims the benefit of Japanese Patent Application No.
2014-067213 filed on Mar. 27, 2014, the entire contents of which
are incorporated herein by reference.
BACKGROUND
Technical Field
[0002] The present invention relates to a shovel having a turning
body mounted on a running body, and a control method thereof.
Description of Related Art
[0003] In the technical field of construction machines such as a
shovel having a turning body that is turnably mounted on a running
body, there is known a technique to stop a turning operation of the
turning body when an entering object enters a turning range. This
kind of shovel stops the turning operation of the turning body by
shutting off the supply of operating oil to a turning hydraulic
motor.
[0004] However, it is difficult for the above-mentioned shovel to
stop the turning body immediately after shutting off the supply of
operating oil to the turning hydraulic motor due to a moment of
inertia. This is because an attachment having a large moment of
inertia is attached to the turning body of the shovel, which causes
the moment of inertia of the turning body to become large. That is,
the large moment of inertia of the attachment causes the turning
body to be difficult to make an immediate stop.
[0005] Thus, it is desirous to develop a technique to reliably
avoid a contact between a shovel and an entering object when the
entering object enters a monitoring range of the shovel.
SUMMARY
[0006] According to an aspect of the invention, there is provided a
shovel including a lower running body and an upper turning body
that is turnably provided on the lower running body. An engine is
mounted on the upper turning body. A hydraulic pump is driven by
the engine to discharge an operating oil. A hydraulic actuator is
mounted on the upper turning body. A control device controls
operations of the shovel. An entering object detection device
detects a position of an entering object in a monitoring area of
the shovel and outputs a detection signal indicating the detection
position of the entering object. The control device supplies, after
a determination of an entry of the entering object into the
monitoring area, the operating oil from the hydraulic pump to the
hydraulic actuator.
[0007] There is provided according to another aspect of the
invention a control method of a shovel that includes a control
device that controls operations of the shovel, and an entering
object detection device that detects a position of an entering
object that has entered a monitoring area of the shovel. The
control method includes determining an entry of the entering object
into the monitoring area based on a detection signal from the
entering object detection device; and supplying an operating oil
from a hydraulic pump to a hydraulic actuator after the
determination of an entry of the entering object.
[0008] The object and advantages of the embodiments will be
realized and attained by means of the elements and combinations
particularly pointed out in the appended claims.
[0009] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory only and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a side view of a shovel according to an embodiment
of the present invention;
[0011] FIG. 2 is a block diagram illustrating a configuration of a
drive system of the shovel illustrated in FIG. 1;
[0012] FIG. 3 is a plan view of the shovel and an entering object
with illustration of monitoring areas;
[0013] FIG. 4 is an illustration indicating a positional
relationship between the shovel and the entering object;
[0014] FIG. 5 is a circuit diagram of a hydraulic system of the
shovel;
[0015] FIG. 6 is a hydraulic circuit diagram of a hydraulic circuit
provided in the hydraulic system illustrated in FIG. 5;
[0016] FIGS. 7A and 7B are graphs for explaining a control
operation of the shovel provided with the hydraulic circuit
illustrated in FIG. 6;
[0017] FIG. 8 is a hydraulic circuit diagram of the hydraulic
system according to another embodiment;
[0018] FIG. 9 is a graph for explaining a control operation of the
shovel provided with the hydraulic circuit illustrated in FIG.
8;
[0019] FIG. 10 is an illustration for explaining a control
operation of the shovel according to a further embodiment;
[0020] FIG. 11 is a an illustration for explaining a turning
mechanism for turning the upper turning body;
[0021] FIG. 12 is a graph for explaining a control operation of the
shovel equipped with the turning mechanism illustrated in FIG.
11;
[0022] FIG. 13 is a flowchart of a control process of the
shovel;
[0023] FIG. 14 is a hydraulic circuit diagram of a hydraulic
circuit between the operation lever and the flow control valve
according to another embodiment;
[0024] FIG. 15 is a hydraulic circuit diagram of a hydraulic
circuit between the operation lever and the flow control valve
according to a further embodiment;
[0025] FIG. 16 is a hydraulic circuit diagram of a hydraulic
circuit between the operation lever and the flow control valve
according to yet another embodiment; and
[0026] FIG. 17 is a block diagram of a structure of a drive system
different from the drive system illustrated in FIG. 2.
DETAILED DESCRIPTION
[0027] First, a description will be given, with reference to FIG.
1, of a shovel according to an embodiment of the present invention.
FIG. 1 is a side view of the shovel according to the embodiment.
The shovel illustrated in FIG. 1 includes a lower running body 1
and an upper turning body 3 that is mounted on the lower running
body 1 via a turning mechanism 2. A boom 4 is mounted to the upper
turning body 3. An arm 5 is attached to an extreme end of the boom
4, and the bucket 6 is attached to an extreme end of the arm 5. The
boom 4, arm 5 and bucket 6 (corresponding to an attachment 125
mentioned later) are hydraulically driven by a boom cylinder 7, an
arm cylinder 8 and a bucket cylinder 9, respectively. The upper
turning body 3 is provided with a cabin 10 and also mounted with a
power source such as an engine 11 or the like. The cabin 10 is
provided with a driver's seat so that a driver can operate the
shovel while sitting in the driver's seat.
[0028] FIG. 2 is a block diagram illustrating a structure of a
drive system of the shovel illustrated in FIG. 1. In FIG. 2, double
lines denote a mechanical drive system, bold solid lines denote
high-pressure hydraulic lines, thin dashed lines denote pilot
lines, and bold dotted lines denote electric drive/control
lines.
[0029] The drive system of the shovel mainly includes an engine 11,
a regulator 13, a main pump 14, a pilot pump 15, a control valve
17, an operation device 26, a pressure sensor 29, and a controller
30.
[0030] The engine 11 is a power source of the shovel, which, for
example, operates to maintain a predetermined revolution speed. The
output axis of the engine 11 is connected to the input axis of the
main pump 14.
[0031] The main pump 14 is a hydraulic pump for supplying operating
oil to the control valve 17 through a high-pressure hydraulic line,
and is, for example, a swash plate type variable capacity hydraulic
pump. The main pump 14 discharges the operating oil by the
revolution power of the engine 11.
[0032] The regulator 13 is a device for controlling an amount of
discharge of the main pump 14. The regulator 13 controls an amount
of discharge of the main pump 14 by, for example, adjusting a swash
plate inclination angle of the main pump 14 in response to a
discharge pressure of the main pump 14 or a control signal from the
controller 30.
[0033] The pilot pump 15 is a hydraulic pump for supplying
operating oil to various hydraulically controlled devices through a
pilot line, and is, for example, a fixed capacity hydraulic pump.
The pilot pump 15 is connected with an operation device 26 through
a pilot line 25.
[0034] The control valve 17 is a hydraulic control device for
controlling a hydraulic system in the shovel. The boom cylinder 7,
the arm cylinder 8, the bucket cylinder 9, a running hydraulic
motor 1A (right), a running hydraulic motor 1B (left) and a turning
hydraulic motor 21 are connected to the control valve 17 through
high-pressure hydraulic lines. The control valve 17 selectively
supplies operating oil discharged by the main pump 14 to one or
more of the boom cylinder 7, the aim cylinder 8, the bucket
cylinder 9, the running hydraulic motor 1A (right), the running
hydraulic motor 1B (left) and the turning hydraulic motor 21. In
the following description, the boom cylinder 7, the arm cylinder 8,
the bucket cylinder 9, the running hydraulic motor 1A (left), the
running hydraulic motor 1B (right) and the turning hydraulic motor
21 may be collectively referred to as the "hydraulic
actuators".
[0035] The operation device 26 includes a lever 26A, a lever 26B
and a pedal 26C. The levers 26A, 26B and 26C are connected to the
control valve 17 and a pressure sensor 29 through pilot lines 27
and 28, respectively. The pressure sensor 29 is connected to a
controller 30 that performed a drive control of an electric system.
In the present embodiment, the lever 26A serves as both a turning
lever and an arm lever. The lever 26B serves as both a boom lever
and a bucket lever.
[0036] The operation device 26 is used by an operator to operate
the hydraulic actuators. The operation device 26 supplies the
pressurized operating oil, which is received from the pilot pump
15, to pilot ports of the flow control valve corresponding to the
respective hydraulic actuators. The pressure of the pressurized
operating oil supplied to the pilot port of each of the flow
control valve corresponds to a direction of operation and an amount
of operation of the respective one of the levers 26A and 26B and
pedal 26C of the operation device 26 corresponding to the
respective one of the hydraulic actuators.
[0037] The turning hydraulic motor 21 is connected to the control
valve 17 to drive the turning mechanism 2. Although the turning
hydraulic motor 21 is connected to the control valve 17 through a
hydraulic circuit of a turning control device, the hydraulic
circuit of the turning drive device is not illustrated in FIG. 2.
The turning drive device will be described later.
[0038] The pressure sensor 29 is a sensor to detect an operation by
the operator applied to the operation device 26. For example, the
pressure sensor 29 detects, in the form of pressure, a direction of
operation and an amount of operation applied to the lever 26A or
26B or the pedal 26C of the operation device 26 corresponding to
the respective one of the hydraulic actuators, and outputs the
value of the detected pressure to the controller 30.
[0039] The controller 30 is a control device for controlling the
shovel, and is constituted by, for example, a computer equipped
with a CPU (Central Processing Unit), a RAM (Random Access Memory),
a ROM (Read Only Memory), etc. The controller 30 is materialized by
the CPU executing a drive control program stored in the internal
memory.
[0040] Specifically, the controller 30 receives the detected value
output by a position detector 22, the pressure sensor 29, etc., and
performs an avoiding operation of the upper turning body 3 or the
attachment based on the output values of these sensors. The
position detector 22 will be mentioned later.
[0041] A description is given, with reference to FIG. 3, of a
positional relationship between the shovel and an entering object.
FIG. 3 is a plan view of the shovel illustrated in FIG. 1 and an
entering object (worker).
[0042] The position detector 22 (refer to FIG. 2) includes a boom
angle sensor 22A, an arm angle sensor 22B and a bucket cylinder
stroke sensor 22C (these sensors are not illustrated in FIG.
3).
[0043] A turning angle sensor 22D is attached to the upper turning
body 3. The turning angle sensor 22D measures a turning angles of
the upper turning body 3 or the attachment 125 from first through
third directions.
[0044] For example, a forward direction of the running direction of
the lower running body 1 is set to the first reference direction.
When the lower running body 1 is placed on a reference horizontal
plane, an xyz-coordinates system is defined wherein a direction
from a turning center 111 toward a remote end of the attachment 125
in the reference horizontal plane is defined as x-axis, a direction
perpendicular to x-direction in the reference horizontal plane is
defined as y-direction, and the turning center 111 is defined as
z-axis.
[0045] A first monitoring area 18a is defined by a fan-shaped area
having a center as the turning center 111 (z-axis). The first
monitoring area 18a is symmetric, in a plan view, with respect to
the center line of the attachment 125. A half (1/2) of the center
angle of the first monitoring area 18a is referred to as the "first
monitoring angle upper limit value .alpha.d".
[0046] A distance R from the turning center to the attachment 125
(hereinafter, referred to as the "attachment length" fluctuates
when swinging the boom 4, aim 5 and bucket 6. The radius of the
first monitoring area 18a is equal to the attachment length R.
[0047] A line extending from the turning center 111 and passing
through a front corner of the upper turning body 3 is defined as
the second reference direction. An x'y'z-coordinates system is
defined wherein a direction of the line extending from a turning
center 111 and passing through the front corner of the upper
turning body 3 in the reference horizontal plane is defined as
x'-direction and a direction perpendicular to x'-direction in the
reference horizontal plane is defined as y'-direction. The radius
of a second monitoring area 18b is defined as R'.
[0048] The second monitoring area 18b is defined by a fan-shaped
area having a center as the turning center 111 (z-axis). The second
monitoring area 18b is symmetric, in a plan view, with respect to
x'-axis. A half (1/2) of the center angle of the second monitoring
area 18b is referred to as the "second monitoring angle upper limit
value .alpha.d".
[0049] A line extending from the turning center 111 and passing
through a rear corner of the upper turning body 3 is defined as the
third reference direction. An x''y''z-coordinates system is defined
wherein a direction of the line extending from a turning center 111
and passing through the rear corner of the upper turning body 3 in
the reference horizontal plane is defined as x''-direction and a
direction perpendicular to x''-direction in the reference
horizontal plane is defined as y''-direction. The radius of a third
monitoring area 18c is defined as R''.
[0050] The third monitoring area 18c is defined by a fan-shaped
area having a center as the turning center 111 (z-axis). The third
monitoring area 18c is symmetric, in a plan view, with respect to
x''-axis. A half (1/2) of the center angle of the third monitoring
area 18c is referred to as the "third monitoring angle upper limit
value .alpha.d"".
[0051] The first through third monitoring areas 18a, 18b and 18c
can be set arbitrarily.
[0052] The upper turning body 3 is attached with, for example, to
total of three entering object detection devices 80 on the rear and
left and right. When an entering object (for example, an entering
person or worker W) enters the monitoring area of the shovel, a
transmitter 222 is attached to a predetermined position of the
entering person at the entrance. The transmitter 222 is removed
from the worker when the worker goes out of the monitoring area
(work area). For example, an omnidirectional marker light emitter
is used as the transmitter 222. For example, a CCD camera for
capturing an image of the transmitter is used as each of the
entering object detection device 80. A position of the transmitter
222 can be calculated by taking the image of the transmitter 22 by
a plurality of entering object detection devices 80. Because the
entering object detection devices 80 are attached to the upper
turning body 3, the calculated position of the transmitter 222 is
detected as a relative position to the upper turning body 3. Each
of the entering object detection devices 80 is not limited to the
CCD camera, and a laser radar, millimeter-wave laser, ultrasonic
sensor, infrared sensor, etc., may be used. Any kind of detector
can be used if it can detect the entering person W.
[0053] FIG. 4 is an illustration indicating a positional
relationship in a height direction and a transverse direction
between the shovel illustrated in FIG. 1 and the entering
object.
[0054] The transmitter 222 is attached to the highest position of a
load-carrying tray of a dump truck W' as the entering object. The
boom 4 swings u and down about a swing center 112, which is
parallel to y-axis. The boom angle sensor 22A and the arm angle
sensor 22B as the position detector 22 are attached to the
connecting part between the upper turning body 3 and the boom 4 and
the connecting part between the boom 4 and the arm 5, respectively.
The bucket cylinder 9 is attached with the bucket cylinder stroke
sensor 22C as the position detector 22. The boom angle sensor 22A
measures an angle .beta.1 formed between the longitudinal direction
of the boom 4 and the reference horizontal plane (xy-plane). The
arm angle sensor 22B measures an angle .delta.1 formed between the
longitudinal direction of the boom 4 and the longitudinal direction
of the aim 5. The bucket cylinder stroke sensor 22C measures an
angle .delta.2 formed between the longitudinal direction of the arm
5 and the longitudinal direction of the bucket 6 based on a stroke
of the bucket cylinder 9.
[0055] Here, the longitudinal direction of the boom 4 is a
direction of a line passing through the swing center 112 and the
connecting part between the boom 4 and the arm 5 in a plane
(zx-plane) perpendicular to the swing center 112. The longitudinal
direction of the arm 5 is a direction of a line passing through the
connecting part between the boom 4 and the aim 5 and the connecting
part between the arm 5 and the bucket 6 in zx-plane. The
longitudinal direction of the bucket 6 is a direction of a line
passing through the connecting part between the aim 5 and the
bucket 6 and an extreme end of the bucket 6 in zx-plane.
[0056] The swing center 112 is located at a position displaced from
the turning center 111 (z-axis). A structure in which the turning
center 111 and the swing center 112 intersect with each other may
be made.
[0057] A description is given, with reference to FIG. 5, of a
hydraulic system of the shovel according to the present embodiment.
FIG. 5 illustrates a structure of the hydraulic system mounted to
the shovel according to the present embodiment illustrated in FIG.
1. In FIG. 5, double lines denote a mechanical power system, solid
lines denote high-pressure hydraulic lines, dashed lines denote
pilot lines, and dotted lines denoted an electric control
system.
[0058] In FIG. 5, the hydraulic system causes the operating oil to
circulate from the main pumps 14L and 14R, which are driven by the
engine 11, to an operating oil tank through center bypass pipe
paths 40L and 40R, respectively.
[0059] The center bypass pipe path 40L is a high-pressure hydraulic
line passing through flow control valves 151, 155 and 157. The
center bypass pipe path 40R is a high-pressure hydraulic line
passing through flow control valves 152, 154 and 158.
[0060] The operation device 26 is used for operating the shovel.
The operation device 26 supplies a control pressure corresponding
to a lever operation amount to one of left and right pilot ports of
the flow control valve using the operating oil discharged by the
pilot pump 15.
[0061] The pressure sensor 29 detects operation contents of the
operator to the operation device 26 by a form of pressure, and
outputs the detected value to the controller 30. The operation
contents are, for example, a lever operation direction, a lever
operation amount (lever operation angle), etc.
[0062] The operation device 26 includes the operation levers, a
remote control valve and the pressure sensor 29. The operating oil
discharged from the pilot pump 15 is supplied to the remote control
valve. Pilot lines 28R and 28L are connected to the pilot lines 27R
and 27L extending from the remote control valve. The other ends of
the pilot lines 28R and 28L are connected to the pressure sensor
29.
[0063] The flow control valve 151 is a spool valve that switches a
flow of the operating oil in order to supply the operating oil
discharged from the main pump 14L to the running hydraulic motor
1B. The flow control valve 152 is a spool valve that switches a
flow of the operating oil in order to supply the operating oil
discharged from the main pump 14R to the running hydraulic motor
1A.
[0064] The flow control valve 154 is a spool valve that switches a
flow of the operating oil in order to supply the operating oil
discharged from the main pump 14R to the boom cylinder 7 and
discharge the operating oil in the boom cylinder 7 to the operating
oil tank.
[0065] The flow control valve 155 is a spool valve that switches a
flow of the operating oil in order to supply the operating oil
discharged from the main pump 14L to the aim cylinder 8 and
discharge the operating oil in the aim cylinder 8 to the operating
oil tank.
[0066] The flow control valve 157 is a spool valve that switches a
flow of the operating oil in order to circulate the operating oil
discharged from the main pump 14L through the turning hydraulic
motor 21.
[0067] The flow control valve 158 is a spool valve that switches a
flow of the operating oil in order to supply the operating oil
discharged from the main pump 14R to the bucket cylinder 9 and
discharge the operating oil in the bucket cylinder 9 to the
operating oil tank.
[0068] A description is given of a turning drive device that
controls a drive of the turning hydraulic motor 21. The turning
drive device includes a hydraulic circuit for driving the turning
hydraulic motor 21. The hydraulic circuit of the turning drive
device is provided between the turning hydraulic motor 21 and the
control valve 17.
[0069] When the high-pressure operating oil is supplied to an A
port of the turning hydraulic motor 21 from the flow control valve
157 through a hydraulic line 322A, the turning hydraulic motor 21
rotates in a predetermined direction. The high-pressure operating
oil supplied to the A port drives the turning hydraulic motor 21
and turns into the low-pressure operating oil, and discharged from
a B port and returns to the flow control valve 157 through a
hydraulic line 322B. On the other hand, when the high-pressure
operating oil is supplied to the B port of the turning hydraulic
motor 21 from the flow control valve 157 through a hydraulic line
322B, the turning hydraulic motor 21 rotates in a reverse
direction. The high-pressure operating oil supplied to the B port
drives the turning hydraulic motor 21 and turns into the
low-pressure operating oil, and discharged from the A port and
returns to the flow control valve 157 through a hydraulic line
322A.
[0070] A rotation axis of the turning hydraulic motor 21 is
connected to the turning mechanism 2 via a transmission (not
illustrated in the figure). The turning mechanism is operated by
the turning hydraulic motor 21 being driven to rotate, which causes
the upper turning body 3 to turn. The upper turning body 3 is
turned in a rightward direction by rotating the turning hydraulic
motor 21 in one direction, and the upper turning body 3 is turned
in a leftward direction by rotating the turning hydraulic motor 21
in an opposite direction.
[0071] The hydraulic line 322A is connected with a hydraulic
pressure supply port of a relief valve 324A. A hydraulic pressure
release port of the relief valve 324A is connected to a hydraulic
line 326. The hydraulic line 326 is a line through which the
low-pressure operating oil flows to return to the operating oil
tank 330. Similarly, the hydraulic line 322B is connected with a
hydraulic pressure supply port. A hydraulic pressure release port
of the relief valve 324B is connected to the hydraulic line
326.
[0072] A brake plate 23a is attached to the output axis of the
turning hydraulic motor 21. A cylinder 23e that is equipped with a
brake disc 23b, a piston 23c and a spring 23d is provided near the
end of the brake plate 23a. The cylinder 23e is configured to
release a braking force of the brake when the operating oil is
supplied from the pilot pump 15 and actuate the brake when the
supply of the operating oil from the pilot pump 15 is stopped. The
supply of the operating oil is controlled by a solenoid switching
valve 50.
[0073] The regulators 13L and 13R constituting the regulator 13
adjust the swash plate angles of the main pumps 14L and 14R in
response to discharge pressures of the main pumps 14L and 14R,
respectively.
[0074] The controller receives the output of the pressure sensor
29, and outputs, if necessary, a control signal to the regulators
13L and 13R so as to change discharge amounts of the main pumps 14L
and 14R.
[0075] A switch S1 connected to the controller 30 switches
activation/stop of each of the main pumps 14L and 14R. The switch
S1 is provided in the cabin 10.
[0076] When the controller 30 determines that an entering object,
such as an entering person W, a dump truck W', etc., exists in the
monitoring area (first through third monitoring areas 18a, 18b and
18c), the controller 30 controls the shovel to avoid a contact
between the entering object and the shovel.
[0077] FIG. 6 is a hydraulic circuit diagram of the hydraulic
circuit provided between the operation lever and the flow control
valve in the hydraulic system illustrated in FIG. 5. A description
is given of a hydraulic circuit provided between the turning lever
26A and the flow control valve 157.
[0078] The pilot pump 15 generates a pilot pressure necessary for
the hydraulic operating system. The generated pilot pressure is
supplied to the turning lever 26A through the pilot line 25. The
turning lever 26A is operated by an operator. The turning lever 26A
converts a primary side hydraulic pressure supplied from the pilot
line 25 into a secondary side hydraulic pressure. The secondary
side hydraulic pressure is transmitted to solenoid proportional
valves 157a and 157b through pilot lines 27R and 27L, and also
transmitted to the R port or L port of the flow control valve 157
through pilot lines 37R and 37L.
[0079] The operation device for turning is constituted by the
turning lever 26A and remote control valves 257R and 257L.
[0080] Each of the remote control valves 257R and 257L is a valve
for outputting a pilot pressure corresponding to an operation
amount of the turning lever 26A to the flow control valve 157. The
solenoid proportional valves 157a and 157b are arranged between the
turning lever 26A and the flow control valve 157.
[0081] Specifically, the remote control valve 257R is connected to
the R port of the flow control valve 157 by the pilot lines 27R and
37R via the solenoid proportional valve 157a. The remote control
valve 257L is connected to the L port of the flow control valve 157
by the pilot lines 27L and 37L via the solenoid proportional valve
157b. Each of the remote control valves 257R and 257L receives a
pressure of the operating oil supplied by the pilot pump 15 as a
primary pressure, and outputs a secondary pressure corresponding to
an operation amount of the turning lever 26A as a pilot
pressure.
[0082] The pilot pressure input to the flow control valve 157 is
switched by the solenoid proportional valves 157a and 157b.
[0083] Specifically, the solenoid proportional valve 157a is a
4-port 3-position valve. A first port of the solenoid proportional
valve 157a is connected to the R port of the flow control valve 157
through the pilot line 37R. A second port of the solenoid
proportional valve 157a is connected to the remote control valve
257R through the pilot line 27R. A third port of the solenoid
proportional valve 157a is connected to the pilot pump 15 through
the pilot line 25. A fourth port of the solenoid proportional valve
157a is connected to the tank.
[0084] Similar to the solenoid proportional valve 157a, the
solenoid proportional valve 157b is also a 4-port 3-position valve.
The connection relationship of first port through fourth port is
basically the same as the connection relationship of the solenoid
proportional valve 157a, and a description thereof will be
omitted.
[0085] Each of the solenoid proportional valves 157a and 157b
switches the secondary pressure of the operating oil discharged by
the pilot pump 15 so as to switch the flow control valve 157
according to a signal supplied from the controller 30.
[0086] When the solenoid proportional valve 157a is at a neutral
position, the pilot line 27R is set in a communicated state with
the pilot line 37R. Thus, if the operator operates the turning
lever 26A in a rightward turning direction, the secondary pressure
of the operating oil discharged by the pilot pump 15 is supplied to
the R port of the flow control valve 157 through the first and
second ports of the solenoid proportional valve 157. Then, the flow
control valve 157 is switched from the neutral position a to a
right side position b. Thereby, the center bypass pipe path 40L is
set in the communicated state with the hydraulic line 322B, and a
discharge side port of the main pump 14L is set in the communicated
state with the B port of the turning hydraulic motor 21 (refer to
FIG. 5). Thus, the high-pressure operating oil discharged from the
main pump 14L is supplied to the B port of the turning hydraulic
motor 21, and the turning hydraulic motor 21 turns in the rightward
turning direction, which changes the high-pressure operating oil
into a low-pressure operating oil. The low-pressure operating oil
is discharged from the A port of the turning hydraulic motor 21,
and returns to the flow control valve 157 through the hydraulic
line 322A. In this case, the B port serves as a suction side port,
and the A port serves as a discharge side port.
[0087] When the operator intends to decelerate or stop the turning
operation of the upper turning body 3, the operator returns the
turning lever 26A to the neutral position, which causes the center
bypass pipe path 40L to be set in the non-communicated state with
the hydraulic line 322B. That is, the discharge side port of the
main pump 14L is set in the communicated state with the B port of
the turning hydraulic motor 21. Then, the supply of the
high-pressure operating oil from the main pump 14L to the turning
hydraulic motor 21 is stopped. When the flow control valve 157 is
closed, the operating oil is not supplied from the main pump 14L to
the flow control valve 157 and the operating oil discharged from
the A port of the turning hydraulic motor 21 cannot return to the
tank via the flow control valve 157.
[0088] A description is given of a case where the hydraulic circuit
is not provided with the solenoid proportional valves 157a and 157b
in the pilot lines 27R and 27L, respectively. When the flow control
valve is set in the neutral position a to set the center bypass
pipe path 40L and the hydraulic line 322B in the non-communicated
state with each other, which causes the supply of the operating oil
from the main pump 14L to the flow control valve 157 to stop, the
hydraulic pressure at the discharge side A port, which is at a low
pressure, is increased. Thereafter, when the pressure of the
operating oil at the discharge side port exceeds a relief pressure
previously set by the relief valve 324A, the operating oil returns
to the tank via the hydraulic line 326. Thereby, a braking force is
generated by the relief valve 324A, but the pressure at the
discharge side A port decreases because there is no operating oil
supplied to the supply side B port. As a result, the braking force
is decreased, which causes a time period from the deceleration to
the stop of the upper turning body 3.
[0089] Thus, according to the present embodiment, the solenoid
proportional valves are provided to shorten the time period from
the deceleration to the stop of the upper turning body 3. In order
to do that, the flow of the operating oil from the main pump 14L is
automatically switched irrespective of or irrelevant to the lever
operation by the operator. Thereby, a large braking force is
applied continuously to the turning hydraulic motor 21, which
permits a faster stop of the turning operation of the upper turning
body 3.
[0090] Here, a consideration is given of a case where the
controller 30 detects an entering object while the upper turning
body 3 is turning in the rightward direction.
[0091] The turning operation of the upper turning body 3 in the
rightward direction can be performed by the operator operating the
turning lever 26A to the right turn side, which causes a pilot
pressure corresponding to the operation amount of the turning lever
26A to be supplied to the R port of the flow control valve 157
through the solenoid proportional valve 157a. Thereby, the center
bypass pipe path 40L and the hydraulic line 322B are set in the
communicated state, and the discharge side port of the main pump
14L is set in the communicated state with the B port of the turning
hydraulic motor 21 (refer to FIG. 5). Thus, the flow control valve
157 is switched to the right side position b, and the high-pressure
operating oil discharged by the main pump 14L is supplied to the B
port of the turning hydraulic motor 21. The operating oil supplied
to the turning hydraulic motor 21 is discharged from the A port so
that the turning hydraulic motor 21 performs the rightward turning
operation. At this time, the solenoid proportional valves 157a and
157b are at the neutral position a.
[0092] If the controller 30 detects an entering object, the
controller 30 switches the solenoid proportional valve 157a from
the neutral position a to the right side position b and also
switches the solenoid proportional valve 157b from the neutral
position a to the left side position c. A predetermined signal
pattern is previously stored in the internal memory of the
controller 30. The controller 30 outputs a control signal to the
solenoid proportional valves 157a and 157b based on the
predetermined signal pattern. Thereby, the pilot line 37R is set in
the communicated state with the tank port, and the pilot line 25 is
set in the communicated state with the pilot line 37L. Accordingly,
by switching the solenoid proportional valve 157a from the neutral
position a to the right side position b, the pilot line 37R is open
to the tank, which causes the pressure in the pilot line 37 to
become a low pressure. Additionally, by switching the solenoid
proportional valve 157a from the neutral position a to the left
side position c, the secondary pressure of the operating oil
discharged from the pilot pump 15 is supplied to the L port of the
flow control valve 157.
[0093] Accordingly, a pressure difference is generated between the
R port and L port of the flow control valve 157 and the flow
control valve 157 is switched to the left side position c, which
causes the discharge side port of the main pump 14L and the A port
of the turning hydraulic motor 21 to be set in the communicated
state (refer to FIG. 5). Thus, the high-pressure operating oil
discharged from the main pump 14L is supplied to the A port of the
turning hydraulic motor 21. In this case, the B port serves as the
discharge side port, and the A port serves as the suction side
port.
[0094] By providing the solenoid proportional valves 157a and 157b,
the flow of the operating oil supplied to the turning hydraulic
motor 21 is switched to a reverse direction irrespective of or
irrelevant to the operation of the turning lever 26A by the
operator. That is, by providing the solenoid proportional valves
157a and 157b, the operation of the turning hydraulic motor can be
separated from the operation of the turning lever 26A by the
operator. Accordingly, the pressure at the A port becomes a
high-pressure, which permits a high braking force at the A port.
Thereby, a large braking force is exerted in a reverse direction of
the rotating direction of the rotation by inertia. Thus, the upper
turning body 3 or the turning mechanism 2 can be caused to perform
an avoiding operation even at a time when the controller 30 detects
an entering object.
[0095] As mentioned above, if the controller 30 determines that an
entering object enters the monitoring areas 18a, 18b and 18c, the
operating oil is supplied from the main pump 14L to the turning
hydraulic motor 21 irrespective of the operation of the turning
lever 26A by the operator depending on the circumstances. That is,
a large braking force is applied to the turning hydraulic motor 21
in a reverse direction of the turning direction.
[0096] Specifically, if it is determined by the controller 30 that
an entering object enters the monitoring areas 18a, 18b and 18c,
the controller switches the solenoid proportional valves 157a and
157b to cause the main pump 14L and either one of the ports of the
turning hydraulic motor 21 to be set in the communicated state.
More specifically, the controller 30 switches the solenoid
proportional valves 157a and 157b so that the operating oil is
supplied to the port opposite to the port to which the operating
oil is being supplied due to the lever operation of the operator
before the determination. Then, the controller 30 sets the pilot
line 27R (or 27L) in the communicated state with the pilot line 37R
(or 37L) to supply the secondary pressure from the pilot pump 15 to
the R port or the L port of the flow control valve 157. The
controller 30 switches the flow control valve 157 as mentioned
above so as to set the discharge side port of the main pump 14L in
the communicated state with either one of the ports of the turning
hydraulic motor 21. That is, the high-pressure operating oil from
the main pump 14L is supplied to the port (A port or B port)
opposite to the port to which the operating oil is being supplied
due to the lever operation of the operator. Thereby, the turning
operation of the upper turning body 3 is controlled irrespective of
the lever operation by the operator.
[0097] The detection signals of the entering object detection
device 80 and the sensors 22A-22D are sent to the controller 30.
Upon reception of the detection signals, the controller 30 outputs
a control signal to the solenoid proportional valve.
[0098] According to the present embodiment, a braking distance can
be shortened by applying a turning force (braking force) in an
opposite direction to the turning direction of the upper turning
body 3. This can avoid the shovel from being brought into
contacting with an entering object.
[0099] Additionally, if the operator firmly grasps the turning
lever 26A, the operation amount of the turning lever 26A may change
due to a vibration of the shovel. In such a case, there may be a
case where the turning operation of the upper turning body 3 does
not stop and the turning operation is continued.
[0100] According to the present embodiment, a large braking force
can be generated for the turning hydraulic motor even in such a
case because the flow of the operating oil can be switched by
switching the solenoid proportional valves 157a and 157b
irrespective of or irrelevant to the changes in the operation
amount of the lever.
[0101] FIGS. 7A and 7B are graphs for explaining a control
operation of the shovel mounted with the hydraulic circuit
illustrated in FIG. 6. In FIGS. 7A and 7B, solid lines indicate a
braking characteristic of a case where a deceleration or stop
control of the turning operation of the upper turning body 3 of the
shovel according to the present embodiment is performed. Dashed
lines indicate, as a comparison example, a braking characteristic
of a case where the above-mentioned control is not performed. The
graph illustrated in FIG. 7A indicates a waveform of the pressure P
at a braking time high-pressure side port of the turning hydraulic
motor 21. The graph illustrated in FIG. 7B illustrates a waveform
of the angular velocity .omega. of the turning hydraulic motor 21.
The graphs of FIGS. 7A and 7B have the same time axis.
[0102] First, a description is given of a case where a deceleration
or stop control of the turning operation of the upper turning body
3 is performed, when the upper turning body 3 is performing a
rightward turning operation, irrespective of or irrelevant to an
operation of the turning lever 26A by the operator. A deceleration
or stop control performed when the upper turning body 3 is
performing a leftward turning operation is opposite to the control
performed when the upper turning body 3 is performing a rightward
turning operation, and a description thereof will be omitted.
[0103] When a rightward turning operation is performed, the
pressure at the braking time high-pressure port of the turning
hydraulic motor 21 changes as follows.
[0104] As indicated in FIG. 7A, in a period from time T0 to time
T1, the turning hydraulic motor 21 is continuously turning at a
fixed angular velocity .omega.0 according to a lever operation by
the operator, and, thus, the upper turning body 3 is set in a
constant velocity state. In this period, the operator tilted the
turning lever 26A toward the right turning side to supply the
operating oil from the pilot pump 15 to the R port of the flow
control valve 157 to switch the flow control valve 157 to the right
side position b. Thus, the high-pressure operating oil is supplied
to the hydraulic line 322B (refer to FIG. 5), and the high-pressure
operating oil flows to the B port of the turning hydraulic motor 21
and the low-pressure operating oil is discharged from the A port of
the turning hydraulic motor 21. Accordingly, the turning hydraulic
motor 21 rotates in the rightward direction.
[0105] If the controller 30 detects an entering object, the control
signal is set in an ON state and the solenoid proportional valves
157a and 157b are switched. Specifically, the solenoid proportional
valve 157a is switched to the right side position b and the
solenoid proportional valve 157b is switched to the left side
position c based on the control signal from the controller 30.
Thereby, the operating oil in the pilot line 37R is released to the
tank, and the operating oil from the pilot pump 15 is supplied to
the pilot line 37L. Thus, the flow control valve 157 is switched
from the right side position b to the left side position c, and the
operating oil from the main pump 14L is supplied to the A port,
which is at a low pressure (refer to FIG. 5). Accordingly, the
pressure in the hydraulic line 322A (braking time high-pressure
side pressure) sharply rises at time T1. When a large amount of the
high-pressure operating oil is supplied to the hydraulic line 322A,
the relief valve 324A is opened, and the pressure in the hydraulic
line 322A reaches the relief pressure PL (relief maximum pressure).
Because the operating oil is continuously supplied to the A port of
the turning hydraulic motor 21, the pressure of the operating oil
in the hydraulic line 322A is maintained at the relief pressure PL.
As a result, after time T1, as indicated by the solid line in the
graph of FIG. 7A, the pressure of the operating oil in the
hydraulic line 322B is fixed at the relief pressure PL. By
continuously supplying the operating oil to the A port of the
turning hydraulic motor 21 by switching the flow of the operating
oil in a reverse direction, a braking force to brake the turning
hydraulic motor 21, which has performed the rightward turning
operation, is generated. Because the operating oil is continuously
supplied to the A port of the turning hydraulic motor 21, the
braking force is maintained. Because the braking force is applied
in a direction of preventing the rotation of the turning hydraulic
motor 21, as indicated by the solid line in the graph of FIG. 7B,
the angular velocity .omega. of the turning hydraulic motor 21
decreases after time T1.
[0106] As a result, as indicated by the solid line in the graph of
FIG. 7B, the angular velocity .omega. of the turning hydraulic
motor 21 decreases faster, and the upper turning body 3 stops at
time T2.
[0107] After the upper turning body 3 is stopped, the solenoid
proportional valve 157b is switched from the left side position c
to the right side position b. The pilot line 37L is open to the
tank and the flow control valve 157 is switched to the neutral
position a.
[0108] Hereinafter the above-mentioned control according to the
present embodiment is referred to as the "reverse lever
control".
[0109] On the other hand, if the solenoid proportional valve 157a
and 157b are not provided in the hydraulic circuit, and when the
controller 30 detects an entering object at time T1, a braking is
applied to the turning hydraulic motor 21 by stopping the supply of
the operating oil by closing the flow control valve 157.
Specifically, the supply of the operating oil to the hydraulic line
322B is stopped. Thereby, the hydraulic pressure at the B port of
the turning hydraulic motor 21 decreases gradually. On the other
hand, when the flow control 157 is closed, the flow of the
operating oil is shut off, and, thereby, the operating oil is
retained in the hydraulic line 322B, which causes the pressure of
the operating oil at the A port to increase. If the pressure
exceeds a predetermined pressure, the pressure of the operating oil
at the A port reaches the relief pressure PL at time T1.
[0110] A braking force can be generated by the turning hydraulic
motor 21 with the increase in the hydraulic pressure at A port.
However, the turning hydraulic motor 21 cannot be decelerated or
stopped instantaneously. That is, the turning hydraulic motor 21
continuously rotates due to an inertial force of the upper turning
body 3, and the angular velocity .omega. of the turning hydraulic
motor 21 decreases gradually as indicated by the dashed line in the
graph of FIG. 7B. With the decrease in the angular velocity
.omega., an amount of operating oil discharged from the A port of
the turning hydraulic motor 21 also decreases. Thus, the pressure
of the operating oil in the hydraulic line 322A gradually
decreases, which results in a gradual decrease in the braking
force.
[0111] Accordingly, time T3 at which the angular velocity .omega.
of the turning hydraulic motor 21 becomes zero is later than time
T2 as illustrated in FIG. 7B. That is, the period spent on stopping
the turning hydraulic motor 21 is longer than that of the present
embodiment in which the braking force to the turning hydraulic
motor 21 can be maintained.
[0112] FIG. 8 is a hydraulic circuit diagram of the hydraulic
circuit according to another embodiment.
[0113] A description is given of the hydraulic circuit for
controlling the drive of the boom cylinder 7. Similar to the
operation of the turning lever 26A, the pilot pressure generated by
the pilot pump 15 is supplied to the boom lever 26B through the
pilot line 25. The boom lever 26B is operated by an operator. The
boom lever 26B converts the primary side hydraulic pressure
supplied from the pilot line 25 into a secondary side hydraulic
pressure in response to the operation applied to the boom lever 26
by the operator. The secondary side hydraulic pressure is
transmitted to solenoid proportional valves 154a and 154b
(switching valves) through pilot lines 27R and 27L, and also
transmitted to a flow control valve 154 through pilot lines 37R and
37L.
[0114] The operation device for operating the boom 4 is constituted
by the boom lever 26B and remote control valves 254R and 254L.
[0115] The remote control valve 254R is a valve for outputting the
pilot pressure, which corresponds to an amount of operation
performed on the boom lever 26B in an upward direction or a
downward direction, to the flow control valve 154. The solenoid
proportional valves 154a and 154b are arranged between the boom
lever 26B and the flow control valve 154.
[0116] Specifically, the remote control valves 254R and 254L are
connected to the R port of the flow control valve 154 by the pilot
lines 27R and 37R via the solenoid proportional valve 154a. The
remote control valve 254L is connected to the L port of the flow
control valve 154 by the pilot lines 27L and 37L via the solenoid
proportional valve 154b. Each of the remote control valves 257R and
257L receives a pressure of the operating oil supplied by the pilot
pump 15 as a primary pressure, and outputs a secondary pressure
corresponding to an operation amount of the boom lever 26B as a
pilot pressure.
[0117] The pilot pressure input to the flow control valve 154 is
switched by the solenoid proportional valves 154a and 154b.
[0118] Specifically, the solenoid proportional valve 154a is a
4-port 3-position valve. A first port of the solenoid proportional
valve 154a is connected to the R port of the flow control valve 154
through the pilot line 37R. A second port of the solenoid
proportional valve 154a is connected to the remote control valve
254R through the pilot line 27R. A third port of the solenoid
proportional valve 154a is connected to the pilot pump 15 through
the pilot line 25. A fourth port of the solenoid proportional valve
154a is connected to the tank.
[0119] Similar to the solenoid proportional valve 154a, the
solenoid proportional valve 154b is also a 4-port 3-position valve.
The connection relationship of first port through fourth port is
basically the same as the connection relationship of the solenoid
proportional valve 154a, and a description thereof will be
omitted.
[0120] In a hydraulic circuit which is not provided with the
solenoid proportional valves 154a and 154b to the pilot lines 27R
and 27L, respectively, the flow control valve 154 is switched to
the neutral position a so as to avoid a contact between the shovel
and an entering object. Thereby, the center bypass pipe path 40R
and the hydraulic lines 322A and 322B are set in the
non-communicated state to stop the supply of the operating oil to
the turning hydraulic motor 21. However, according to this method,
a time period from the deceleration of the upper turning body 3 to
the stop of the upper turning body 3 becomes long.
[0121] Thus, according to the present embodiment, the solenoid
proportional valves 154a and 154b are provided to shorten the time
period from the deceleration to the stop of the upper turning body
3. In order to do that, the flow of the operating oil from the main
pump 14R is automatically switched by switching the flow control
valve 154. Thereby, the boom lever 26B is operated in a downward
direction and the attachment 125 is brought into contact with a
ground. Because a larger braking force is applied to the turning
hydraulic motor, the turning operation of the upper turning body 3
can be stopped more quickly.
[0122] Specifically, the secondary pressure of the operating oil
discharged from the pilot pump 15 is supplied to the R port of the
flow control valve 154 (refer to FIG. 5). If the controller 30
detects an entering object while the upper turning body 3 is
turning, the controller 30 switches the solenoid proportional valve
154a based on the control signal of the controller 30. More
specifically, the controller 30 switches the solenoid proportional
valve 154a from the neutral position a to the left side position c.
At this time, the solenoid proportional valve 154b may be
maintained at the neutral position a. Thereby, the pilot line 25 is
set in the communicated stated with the pilot line 37R, and the
pilot line L is set in the communicated state with the pilot line
37R. By switching the solenoid proportional valve 154a from the
neutral position to the left side position c, the secondary
pressure of the operating oil discharged from the pilot pump 15 is
supplied to the R port of the flow control valve 154. Thereby, the
center bypass pipe path 40R and the hydraulic line 44B are set in
the communicated state with each other, and the discharge side port
of the main pump 14R is set in the communicated state with the rod
side port of the boom cylinder 7. If the boom lever 26B is not
operated by the operator, the L port of the flow control valve 154
is at a low pressure.
[0123] Accordingly, a pressure difference is generated between the
R port and L port of the flow control valve 154 and the flow
control valve 154 is switched to the right side position a. Thus,
even if the operator is not operating the boom lever 26B, the
downward operation of the boom 4 is automatically performed.
[0124] If the boom lever 26B is operated in the upward direction by
the operator, the solenoid proportional valve 154a is switched from
the neutral position a to the left side position c, and the
solenoid proportional valve 154b is switched from the neutral
position a to the right side position b. That is, the pilot line 25
is set in the communicated state with the pilot line 37R, and the
pilot line 37L is set in the communicated state with the tank port.
Thereby, even if the operator is operating the boom lever 26B in
the upward direction, the downward operation of the boom 4 is
performed automatically. That is, by providing the solenoid
proportional valves 154a and 154b, the operation of the boom 4 can
be separated from the operation of the boom lever 26B by the
operator.
[0125] By bringing the attachment 125 into contact with the ground
by performing downward operation of the boom 4, a larger braking
force can be generated in the upper turning body 3. This is
effective in a case where the shovel is closer to the entering
object.
[0126] By providing the solenoid proportional valves 154a and 154b,
the flow of the operating oil from the main pump 14R can be
switched to the boom down direction irrespective of or irrelevant
to the operation of the boom lever 26B by the operator. By bringing
the attachment 125 into contact with the ground, a large braking
force is applied to the turning hydraulic motor 21, which is
rotating due to inertia, in a direction opposite to the rotating
direction of the turning hydraulic motor 21. Thus, even if the
upper turning body 3 is turning at a high speed and the upper
turning body 3 is approaching the entering object at a high speed,
the attachment 125 can be reliably avoided from contacting with the
entering object.
[0127] According to the present embodiment, the braking distance
can be shortened by generating a frictional force by the contact
between the attachment 125 and the ground in a direction opposite
to the turning direction of the upper turning body 3. Thus, the
shovel is avoided from contacting with the entering object.
[0128] Moreover, if the operator firmly holds the turning lever
26A, the operation amount of the turning lever 26A may change due
to a vibration of the shovel. In such a case, there may be a case
where the turning operation of the upper turning body 3 does not
stop and the turning operation is continued.
[0129] As mentioned above, if it is determined by the controller 30
that an entering object enters the monitoring areas 18a, 18b and
18c, the operation oil is supplied from the main pump 14R to the
boom cylinder 7. Then, the solenoid proportional valves 154a and
154b are switched to set the main pump 14R and the rod side port of
the boom cylinder 7 in the communicated state with each other.
Thereby, the grounding of the attachment 125 is performed, and a
large braking force is applied to the turning hydraulic motor 21 in
the opposite direction to the rotating direction of the turning
hydraulic motor 21.
[0130] Specifically, the solenoid proportional valves 154a and 154b
are switched so as to cause the attachment 125 to be grounded to
stop the upper turning body 3. Then, the pilot line 25 is set in
the communicated state with the pilot line 37R to supply the
secondary pressure from the pilot pump 15 to the R port of the flow
control valve 154. Thereby, the low control valve 154 is switched,
and a hydraulic line 44B connected to the rod side of the boom
cylinder 7 is set in the communicated state with the center bypass
pipe path 40R. That is, the discharge side port of the main pump
14R is set in the communicated state with the rod side port of the
boom cylinder 7. As a result, if it is determined by the controller
30 that an entering object enters the monitoring areas 18a, 18b and
18c, the attachment 125 is moved downward and the grounding control
is performed irrespective of the operation of the boom lever 26B by
the operator depending on the circumstances.
[0131] According to the present embodiment, a large braking force
can be generated to the turning hydraulic motor 21 because the flow
of the operating oil can be switched by switching the solenoid
proportional valves 154a and 154b irrespective of changes in the
lever operation amount.
[0132] According to the hydraulic circuit of the present
embodiment, a control to move the attachment 125 upward can be
performed by setting the hydraulic line 44A connected to the head
side of the boom cylinder 7 in the communicated state with the
center bypass pipe path 40R. Such a control is described later.
[0133] FIG. 9 is a graph for explaining the control operation of
the shovel mounted with the hydraulic circuit illustrated in FIG.
8. In FIG. 9, a solid line indicates a braking characteristic in a
case where a control according to the present embodiment to avoid
the attachment 125 from contacting with an entering object is
performed. A single-dashed chain line indicates a braking
characteristic, as a comparison example, in a case where the
reverse lever control is performed as a comparison example. A
dashed line indicates a breaking characteristic, as a comparison
example, in a case where the above-mentioned controls are not
performed. In FIG. 9, the horizontal axis represents time T, and
the vertical axis represents the angular velocity .omega. of the
turning hydraulic motor 21.
[0134] As indicated in FIG. 9, in a period from time T0 to time T1,
the turning hydraulic motor 21 is continuously turning at a fixed
angular velocity .omega.0 according to a lever operation by the
operator, and, thus, the upper turning body 3 is set in a constant
velocity state.
[0135] If the controller 30 detects an entering object at time T1,
the control signal is set in an ON state. Specifically, the
solenoid proportional valve 154a is switched to the left side
position c based on the control signal from the controller 30.
Thereby, the flow control valve 154 is switched to the right side
position b, and the operating oil from the main pump 14R is
supplied to the rode side of the boom cylinder 7. Thus, the
downward operation of the boom 4 is stared, and the attachment 125
including the boom 4 is grounded. According to the grounding
operation, a frictional force is generated between the attachment
125 and the ground, which the frictional force turns into a braking
force to stop the upper turning body 3 from turning. By generating
the braking force, as indicated by the solid line in the graph of
FIG. 9, the angular velocity .omega. of the turning hydraulic motor
21 decreases after time T1. Because a large frictional force is
generated by grounding the attachment 125 by performing the
downward operation of the boom 4, the angular velocity .omega. of
the turning hydraulic motor 21 decreases faster than the others as
indicated by the solid line in the graph of FIG. 9, and the upper
turning body 3 stops at time T4, which is earlier than time T2 and
time T3.
[0136] Even if the turning lever 26A is set at a neutral position
by the operator so as to shut off the supply of the operating oil
from the main pump 14L to generate a braking force, the
above-mentioned grounding control of the attachment 125 is
performed in a case it is difficult to avoid the attachment 125
from contacting with the entering object.
[0137] If the above-mentioned function according to the present
embodiment is not provided, that is, if the solenoid proportional
valves 154a and 154b are not provided between the boom lever 26 and
the flow control valve 154, there may be a case where a braking is
too late depending on the turning speed of the upper turning body
3. That is, the time at which the angular velocity .omega. of the
turning hydraulic motor 21 becomes zero is as late as time T3
(refer to the dashed line in the graph of FIG. 9). However,
according to the present embodiment in which a large breaking force
is generated, the time at which the angular velocity .omega. of the
turning hydraulic motor 21 becomes zero is as early as time T4
(refer to the solid line in the graph of FIG. 9).
[0138] Further, the braking force, which is generated by grounding
the attachment 125 at a high speed by performing the downward
operation of the boom 4, is larger than the braking force generated
in the embodiment illustrated in FIG. 5 in which the flow of the
operating oil in the turning hydraulic motor 21 is switched to
generate a braking force in an opposite direction to the turning
direction. Thus, the time at which the angular velocity .omega. of
the turning hydraulic motor 21 becomes zero is as early as time T4
(refer to the solid line in the graph of FIG. 9) as compared to the
embodiment illustrated in FIG. 5 (refer to the dashed line
extending to time T3 in the graph of FIG. 9).
[0139] FIG. 10 is an illustration for explaining the control
operation of turning the upper turning body 3 of the shovel
according to a further embodiment.
[0140] Unlike the embodiment illustrated in FIG. 9, in the
hydraulic circuit illustrated in FIG. 8, the secondary pressure of
the operating oil discharged from the pilot pump 15 is supplied to
the L port side of the flow control valve 154. If the controller 30
detects an entry of the entering object, the solenoid proportional
valve 154b is switched based on the control signal of the
controller 30 (refer to FIG. 8). More specifically, the solenoid
proportional valve 154b is switched from the neutral position a to
the left side position c. Then, the pilot line 25 is set in the
communicated state with the pilot line 37L to supply the secondary
pressure from the pilot pump 15 to the L port of the flow control
valve 154. Thereby, the flow control valve 154 is switched, and the
hydraulic line 44A, which is connected to the head side of the boom
cylinder 7, is set in the communicated state with the center bypass
pipe path 40R. That is, the discharge side port of the main pump
14R is set in the communicated state with the head side port of the
boom cylinder 7. As a result, the attachment 125 is lifted
irrespective of the lever operation by the operator. The solenoid
proportional valve 154a may be at the neutral position a. By
switching the solenoid proportional valve 154b from the neutral
position a to the left side position c, the pilot line 25 is set in
the communicated state with the pilot line 37L and the pilot line
27R is set in the communicated state with the pilot line 37R. Thus,
the secondary pressure of the operating oil discharged from the
pilot pump 15 is supplied to the L port of the flow control valve
154. When the boom lever 26B is not operated by the operator, the R
port of the flow control valve 154 is at a low pressure.
[0141] Thus, a pressure difference is generated between the R port
and the L port of the flow control valve 154, and the flow control
valve 154 is switched to the left side position c. Thereby, even
when the operator is not operating the boom lever 26B, the lifting
operation of the boom 4 is performed automatically.
[0142] When the boom lever 26B is operated in the downward
direction by the operator, the solenoid proportional valve 154a is
switched from the neutral position a to the right side position b
and the solenoid proportional valve 154b is switched from the
neutral position a to the left side position c. That is, the pilot
line 25 is set in the communicated state with the pilot line 37L
and the pilot line 37R is set in the communicated state with the
tank port. Thereby, even when the operator is operating the boom
lever 26B in the downward direction, the lifting operation of the
boom 4 is performed automatically. As a result, if it is determined
by the controller 30 that an entering object enters the monitoring
areas 18a, 18b and 18c, the avoiding control is performed by
lifting the attachment 125 irrespective of or irrelevant to the
operation of the boom lever 26B by the operator according to the
circumstances.
[0143] More specifically, the lifting operation of the boom 4 is
performed by switching the flow control valve to the left side
position, which causes the operating oil from the main pump 14R to
flow to the head side of the boom cylinder 7 and causes the
operating oil from the rod side to the operating oil tank.
[0144] When the controller 30 detects the entering object, the
control signal is turned to an ON state. Specifically, the solenoid
proportional valves 154a and 154b are switched based on the control
signal from the controller 30. Thereby, the discharge side port of
the main pump 14R is set in the communicated state with the head
side of the boom cylinder 7 to supply the operating oil from the
main pump 14R to the boom cylinder 7. As a result, the operating
oil from the rod side of the boom cylinder 7 is ejected to the
operating oil tank, which causes the lifting operation of the boom
4.
[0145] By performing the lifting operation of the boom 4, as
illustrated in FIG. 10, the attachment including the boom 4 is
moved in the upward direction. By raising the attachment 125 from a
low position (refer to the dashed line in FIG. 10) to a high
position (refer to the solid line in FIG. 10), the attachment 125
is avoided from contacting with the entering object.
[0146] By providing the solenoid proportional valves 154a and 154b,
the lifting operation of the boom 4 is performed automatically
according to the control signal from the controller 30. Thus, the
operation of the attachment 125 including the boom 4 can be
switched to the upward movement irrespective of the operation of
the boom lever 26B by the operator. That is, by providing the
solenoid proportional valves 154a and 154b, the operation of the
boom 4 is separated from the operation of the boom lever 26B by the
operator.
[0147] Accordingly, even if the braking operation is not performed
in time when the operator returns the turning lever 26A to the
neutral position or performs a reverse lever control, the shovel is
reliably avoided from contacting with the entering object by
performing the control operation to move the attachment 125 in the
upward direction.
[0148] Moreover, if the operator is holding the turning lever 26A
or the boom lever 26B, there may be a case where operation amount
of the lever changes due to a vibration of the shovel body. In such
a case, the turning operation of the upper turning body 3 and the
lifting or downward operation of the boom 4 may not be performed as
intended by the operator.
[0149] However, according to the present embodiment, the attachment
125 can be avoided from contacting with the entering object
automatically by switching the solenoid proportional valves 154a
and 154b irrespective of the change in the operation amount of the
lever.
[0150] As mentioned above, if it is determined by the controller 30
that an entering object enters the monitoring areas 18a, 18b and
18c, the operating oil is supplied from the main pump 14R to the
boom cylinder 17. Then, the main pump 14R is set in the
communicated state with the head side port of the boom cylinder 7
by switching the solenoid proportional valves 154a and 154b.
Thereby, the lifting operation of the attachment 125 is performed,
which permits the attachment 125 to avoid from contacting with the
entering object.
[0151] In the following explanation, the above-mentioned control
operation is referred to as the "avoid control".
[0152] As mentioned above, if it is determined by the controller 30
that an entering object enters the monitoring areas 18a, 18b and
18c, the solenoid proportional valves 154a and 154b are set in the
communicated state so that the grounding control of the attachment
125 or the avoid control of the attachment 125 is performed. That
is, the discharge side port of the pilot pump 15 is set in the
communicated state with any one of the ports of the flow control
valve 154. Thereby, the switching operation of the flow control
valve 154 is performed.
[0153] FIG. 11 is an illustration for explaining a turning
mechanism of the shovel according to an embodiment different from
that of FIG. 7.
[0154] A description is given, with reference to FIG. 11, of a
shovel control mechanism according to an embodiment different from
the above-mentioned embodiments.
[0155] As illustrated in FIG. 11, the turning operation of the
upper turning body 3 in the shovel according to the present
embodiment is achieved by causing an inner tooth gear 61, which is
fixed to the lower running body 1, to be engaged with a turning
pinion 62, which is incorporated in the upper turning body 3.
[0156] Specifically, an inner race 63 is driven by the turning
pinion 62 via the inner tooth gear 61 at a low speed and
high-torque. Thereby, a turning frame 3a is rotated together with
an outer race about the turning center 11, which causes the upper
turning body 3 to perform the turning operation. The inner race 63
and an outer race 64 are arranged to make concentric circles with
respect to the turning center 111 of the upper turning body 3. More
specifically, the turning pinion 62 is engaged with the inner tooth
gear 61 formed on the inner periphery of the inner race 63, and the
inner tooth gear 61 is fixed to the turning frame 3a. The upper
turning body 3 performs a turning operation by the turning pinion
62 moving along the inner periphery of the inner race 63.
[0157] By inserting a pin 60 into the inner tooth gear 61 while the
upper turning body 3 is turning, the motion of the inner race 63 is
stopped to forcibly stop (lock) the upper turning body 3. Thereby,
the upper turning body 3 is stopped urgently, which permits
reliable avoiding of the shovel from contacting with the entering
object even if there is a high-possibility of contact with the
entering object. In the following explanation, the above-mentioned
control operation is referred to as the "pin insertion
control".
[0158] FIG. 12 is a graph for explaining a control operation of the
shovel equipped with the turning mechanism illustrated in FIG. 11.
In FIG. 12, a solid line indicates a braking characteristic of the
pin insertion control in the shovel according to the present
embodiment. A single-dashed chain line indicates, as a comparison
example, a braking characteristic, when the reverse lever control
is performed. A double-dashed chain line indicates, as a comparison
example, a braking characteristic when the grounding control of the
attachment is performed. A dashed line indicates, as a comparison
example, a braking characteristic, when the above-mentioned control
is not performed. The vertical axis represents time T, and the
horizontal axis represents the angular velocity .omega. of the
turning hydraulic motor 21.
[0159] In the period from time TO to time T1, the upper turning
body 3 continuously turns at a constant angular velocity .omega.0,
and the upper turning body 3 is in a constant speed state.
[0160] At time T1, when the controller 30 detects an entering
object, the control signal is turned to an ON state. Specifically,
the pin 60 is inserted into the inner tooth gear 61 base on the
control signal from the controller 30. Because the turning pinion
62 is locked by the pin 60 being inserted into the inner tooth gear
61, the drive of the inner race 63 is stopped, and, thereby, the
upper turning body 3 is stopped. As a result, if it is determined
by the controller 30 that an entering object enters the monitoring
areas 18a, 18b and 18c, the pin insertion control is performed
irrespective of the operation of the boom lever 26B by the operator
according to the circumstances. According to the present
embodiment, the upper turning body 3 is stopped simultaneously with
the control signal being turned to the ON state.
[0161] Accordingly, the upper turning body 3 is stopped much faster
than the case where the turning lever 26A is returned to the
neutral position so as to cause the turning hydraulic motor 21 to
generate a braking force (refer to the dashed line in the
figure).
[0162] Moreover, unlike other embodiments (the reverse lever
control, grounding control of the attachment 125, and avoid control
of the attachment 125 attachment), there is no need to spend a
predetermined time from the output of the control signal by the
controller 30 to time (T2, T3 and T4), and the upper turning body 3
can be urgently stopped.
[0163] A description is given, with reference to FIG. 13, of a
control process of the upper turning body 3 or the attachment 125
by the controller 30. FIG. 13 is a flowchart of a control process
performed by the shovel according to the present embodiment.
[0164] As illustrated in FIG. 13, first, the first monitoring area
18a, second monitoring area 18b and third monitoring area 18c are
determined based on the position of the attachment 125 and the
angular velocities .omega., .omega.', .omega.'' of the upper
turning body 3 in a controlling part 30a of the controller 30 (step
ST1). Further, the controller computes the height from the swing
center 112 to the tip of the bucket 6, the attachment length R, and
the radiuses R and R'' based on the results of measurement input
from the angle sensors 22A and 22B and the stroke sensor 22C.
[0165] When the attachment length R is fixed, it is desirous to set
the monitoring angle upper limit value .alpha.d (refer to FIG. 3)
is set larger as the angular velocity .omega. becomes larger.
Moreover, if the angular velocity .omega. is constant, it is
desirous to set the monitoring angle upper limit .alpha.d larger as
the attachment length R becomes longer. This is because the moment
of inertia acted on the shovel becomes large.
[0166] The radius R' of the second monitoring area 18b is fixed. It
is desirous to set the monitoring angle upper limit value .alpha.d
(refer to FIG. 3) larger as the angular velocity .omega.' becomes
larger. Similarly, because the radius R'' of the third monitoring
area 18c is fixed, it is desirous to set the monitoring angle upper
limit value .alpha.d larger as the angular velocity .omega.''
becomes larger.
[0167] According to the above-mentioned results of calculation, the
sizes of the monitoring areas 18a, 18b and 18c are determined.
[0168] Then, the type of the entering object is identified by
analyzing image data input from the entering object detection
device 80. The identification is performed by changing the
light-emitting color of the transmitter 222 attached to the
entering object in response to the type of the entering object. The
determining part 30a of the controller 30 (refer to FIG. 6)
determines the control operation of the upper turning body 3 or the
attachment 125 based on the thus-calculated monitoring areas 18a,
18b and 18c and the type and positional relationship of the
entering object.
[0169] Specifically, the controller determines whether a
possibility of contact (abutment) of the entering object with the
shovel is high so as to determine the control operation of the
upper turning body 3 or the attachment 125 to be used.
[0170] The controller determines which one of the monitoring areas
the entering object enters. This determination is performed by the
determining part 30a of the controller 30 based on the image data
of the entering object detection device 80. When an entering object
enters one of the monitoring areas, for example, an alarm lamp is
turned on or blinked, and sound an alarm buzzer (step ST2). At this
time, the type of alarming may be changed for each emergency area.
Further, the determining part 30a determines a degree of risk
(degree of emergency) of the entering object being contacted with a
drive part including the upper turning body 3 and the attachment
125 (step ST3). According to the degree of risk, the controller 30
determines the avoid control to avoid the drive part from
contacting with the entering object.
[0171] If it is possible that the entering object, which enters the
first monitoring area 18a, comes into contact with the first
attachment 125 or the upper turning body 3 (YES in step ST3), the
determining 30a determines a distance between the entering object
and the attachment 125 or the upper turning body. 3.
[0172] Specifically, the determining part 30a determines whether a
distance between the attachment 125 and the entering object and a
distance between the upper turning body 3 and the entering object
are larger than a predetermined distance. If it is determined in
step ST 4 that each distance is larger than the predetermined
distance (YES in step ST4), the controller 30 performs the "reverse
lever control" (step ST5). The stop operation of the upper turning
body 3 is performed by reversing the flow of the operating oil
circulating through the turning hydraulic motor 21.
[0173] If it is determined in step ST4 that either one of the
distances is not larger than the predetermined distance (NO in step
ST4), it is determined whether a distance between the counter
weight of the upper turning body 3 and the entering object is
longer than the predetermined distance (step ST6). That is, it is
determine in step ST6 whether the upper turning body 3 or the
attachment 125 can avoid from contacting with the entering object
by performing the above-mentioned other control operations when
there is no room in the distance to cope with the "reverse lever
control".
[0174] If it is determined in step ST6 that the distance is longer
than the predetermined distance (NO in step ST6), it is determined
whether the contact can be avoided by lifting the attachment 125
(step ST9). If it is determined in step ST9 that the contact can be
avoided by lifting the attachment 125 (Yes in step ST9), the "avoid
control of the attachment 125" is performed (step ST10).
[0175] On the other hand, if it is determined in step ST6 that the
distance is not longer than the predetermined distance (YES in step
ST6), it is determined whether the contact can be avoided by
grounding the attachment 125 (step ST7). If it is determined in
step ST7 that the contact can be avoided by the grounding (YES in
step ST7), the grounding control of the attachment 125'' is
performed (step ST8).
[0176] If it is determined that it is difficult to avoid the
contact by either one of the "avoid control of the attachment 125"
and the "grounding control of the attachment 125" (NO in steps ST7
and ST9), the "pin insertion control" is performed to forcibly stop
the turning operation of the upper turning body 3 (step ST11).
[0177] In the above-mentioned embodiments, the hydraulic circuits
of the turning lever and the boom lever is illustrated and
explained individually as a hydraulic circuit for performing
switching of the flow control valve by solenoid proportional
valves. However, the present invention is not limited to such as
structure. For example, as illustrated in FIG. 14, both the flow
control valves of the hydraulic circuits of the turning lever and
the boom lever may be switched by the respective solenoid
proportional valves.
[0178] Alternatively, as illustrated in FIG. 15, both the flow
control valves of the hydraulic circuits of the boom lever and the
am lever may be switched by the respective solenoid proportional
valves.
[0179] Alternatively, as illustrated in FIG. 16, all of the flow
control valves of the hydraulic circuits of the boom lever, the arm
lever and the bucket lever may be switched by the respective
solenoid proportional valves.
[0180] The hydraulic circuit of the arm lever causes the operating
oil to be supplied to the R port of the flow control valve 155 by
switching the solenoid valve 155a to the left side position c by
the controller 30. Thereby, the flow control valve 155 is switched
to the right side position b, which causes the operating oil to be
supplied from the main pump 14L to the head side of the arm
cylinder 8 (refer to FIG. 5). Thereby, the lifting operation of the
arm 5 is automatically (forcibly) performed. When performing the
downward operation of the arm 5 automatically, the flow control
valve 155 is switched to the left side position c by switching the
solenoid proportional valve 155b to the left side position c by the
controller 30.
[0181] The hydraulic circuit of the bucket lever causes the
operating oil to be supplied to the R port of the flow control
valve 158 by switching the solenoid valve 158a to the left side
position c by the controller 30. Thereby, the flow control valve
158 is switched to the right side position b, which causes the
operating oil to be supplied from the main pump 14R to the head
side of the bucket cylinder 9 (refer to FIG. 5). Thereby, the
opening operation of the bucket 6 is automatically (forcibly)
performed. When performing the closing operation of the bucket 6
automatically, the flow control valve 158 is switched to the left
side position c by switching the solenoid proportional valve 158b
to the left side position c by the controller 30.
[0182] The operation of the hydraulic circuits illustrated in FIGS.
14 through 16 are basically the same as the hydraulic circuits of
the turning lever 26A and the boom lever 26B, and the descriptions
thereof will be omitted.
[0183] Various operations can be performed in response to the
positional relationship between the shovel and the entering object
by combining the control operation of the boom 4 with the control
operation of the arm 5 or the control operation of the bucket
6.
[0184] Moreover, in the above-mentioned embodiments, the "reverse
control, "avoid control of the attachment 125", "grounding control
of the attachment 125" and "pin insertion control" are illustrated
and explained as the avoiding operation to avoid the shovel and the
entering object from contacting with each other. However, the
present invention is not limited to such a structure. For example,
a braking may be applied to the upper turning body 3 by a
mechanical brake 23 (refer to FIG. 5). Specifically, the mechanical
brake 23 is released, while the upper turning body 3 is turning, by
supplying the operating oil from the pilot pump 15 into the
cylinder 23e. Then, the control signal is sent from the controller
30 in response to the degree of risk (urgency) of contact to switch
the solenoid valve 50. Thereby, the supply of the operating oil
into the cylinder 23e is stopped to actuate the mechanical brake
23, which results in braking applied to the upper turning body 3.
Because braking is applied by the mechanical brake, time T to the
stop of the turning operation of the upper turning body 3 is
reduced as compared to the case where the flow of the operating oil
is shut off by returning the turning lever to the neutral position.
The time from the beginning of deceleration and the stop of the
upper turning body 3 is substantially equal to the of the case
where the "grounding control of the attachment 125" is performed
(refer to the solid line and time T4 in FIG. 9).
[0185] The above mentioned control operations may be performed
individually or some control operations may be combined. Thereby,
the upper turning body 3 or the attachment 125 and the entering
object are avoided from contacting with each other in response to
various circumstances.
[0186] When combining some control operations, it is determined
whether to control the attachment 125 or the turning hydraulic
motor 21 based on a relative distance between the entering object
and the components (the upper turning body, the attachment 125,
etc.) of the shovel or a component of the shovel for which a
possibility of contact with the entering object is high. This
determination is performed by the determining part 30a of the
controller 30.
[0187] The structure of the shovel according to the present
invention is not limited to that illustrated in FIG. 2 in which the
turning hydraulic motor is used as a turning motor. For example,
the present invention can be achieved using a turning electric
motor as illustrated in FIG. 17. In FIG. 17, double lines denote a
mechanical drive system, bold solid lines denote high-pressure
hydraulic lines, thin dashed lines denote pilot lines, and bold
dotted lines denote electric drive/control lines.
[0188] The shovel illustrated in FIG. 17 uses an electrically
operated turning mechanism 2, and is provided with a turning
electric motor 210 for driving the turning mechanism 2. The turning
electric motor 210 as an electric operation element is connected to
an electricity accumulation system 120 through an inverter 20. A
resolver 220, the mechanical brake 23 and a turning transmission 24
are connected to the rotation axis 210A of the turning electric
motor 210. The turning electric motor 210, inverter 20, resolver
220, mechanical brake and turning transmission together constitute
a load drive system.
[0189] The electricity accumulation system 120 including an
electricity accumulator is connected to a motor generator 12 via an
inverter 18A. The electricity accumulation system 120 is
constituted by a voltage up-down converter connected by the
inverters 18A and 20 and a direct current line and the electricity
accumulator connected to the voltage up-down converter. A capacitor
is used as the electricity accumulator. Instead of the capacitor, a
rechargeable secondary battery such as a lithium ion battery, a
lithium ion capacitor or an electricity exchangeable power source
of other forms may be used as the electricity accumulator.
[0190] The engine 11 is provided with a starter motor 11a and a
battery 11b for starting the starter motor 11a. The battery 11b is
a battery generally used for a vehicle, and is, for example, a 24V
lead storage battery. When starting the operation of the shovel, an
electric power is supplied to the starter motor 11a to drive the
starter motor 11a, and the engine 11 is forcibly rotated by the
drive power of the starter motor 11a.
[0191] The shovel illustrated in FIG. 17 can provide the same
action and effect as the shovel using the turning hydraulic motor
21.
[0192] Although the operation levers, which generate a pilot
pressure as an operation signal to the flow control valve, is used
in the above-mentioned embodiments, an electric lever, which
generates an electric signal and sends the electric signal from the
controller to the flow control valves 154, 155, 157 and 158, may be
used other than the operation levers. In such a case, generally,
the operation amount of the electric lever is input to the
controller, and, thereafter, the electric signal corresponding to
the operation amount is sent to the flow control valve to control
the flow control valve. Additionally, if the controller detects an
entering object, the electric signal sent from the controller is
switched from the electric signal corresponding to the operation
amount to the electric signal generated based on previously input
signal patterns. Thus, the flow control valve is controlled base on
the previously input signal patterns.
[0193] Moreover, although a position of the attachment 125 is
calculated using the xyz-coordinate system in the above-mentioned
embodiments, the present invention is not limited to the use of the
xyz-coordinated system. For example, the coordinate may be defined
by latitude and altitude using a global reference coordinate
system. This is effective for a case where a position of an
entering object is measured by GPS.
[0194] The present invention is not limited to the specifically
disclosed embodiments using the above-mentioned shovel as an
example, and various variations and modifications may be made
without departing from the scope of the present invention.
* * * * *