Safety device for mobile crane
A safety device for a mobile crane has: a permitted work range setting unit that, in accordance with whether or not the overhang angle of each outrigger is a reference overhang angle and the overhang length is the maximum overhang length, sets the permitted work range/non-permitted work range of a crane boom; and a load-specific work range setting unit that, in accordance with whether or not each of the outriggers overhang lengths is a maximum overhang length, sets a maximum RTL work range which is a range, within the permitted work range, in which crane work at a maximum rated total load can be carried out. The crane work capacity on the side of the outrigger having the maximum hangover length with high supporting capacity can be fully utilized within a range over which safety can be ensured.
1. A safety device for a mobile crane, which restricts crane work in accordance with respective overhang states of four outriggers of which both overhang length and overhang angle can be varied, the outriggers being attached to a traveling body equipped with a crane boom, the safety device comprising:
a permitted work range setting unit that, in accordance with whether or not each of the outrigger overhang angles is a reference overhang angle, sets a permitted work range in which crane work can be carried out within a crane work area having a maximum work radius centered around a turning center of a crane boom; and
a load-specific work range setting unit that, in accordance with whether or not each of the outriggers overhang lengths is a maximum overhang length, sets a maximum RTL work range which is a range, within the permitted work range, in which at least crane work at a maximum rated total load can be carried out;
wherein the crane work area is sectioned into four turning angle ranges of 90 degrees each, in correlation with the four outriggers centered about the turning center; and
the permitted work range setting unit sets the turning angle ranges assigned to the outriggers, at which the overhang angles are the reference overhang angle, to the permitted work range.
2. A safety device for a mobile crane, which restricts crane work in accordance with respective overhang states of four outriggers of which both overhang length and overhang angle can be varied, the outriggers being attached to a traveling body equipped with a crane boom, the safety device comprising:
a permitted work range setting unit that, in accordance with whether or not each of the outrigger overhang angles is a reference overhang angle, sets a permitted work range in which crane work can be carried out within a crane work area having a maximum work radius centered around a turning center of a crane boom; and
a load-specific work range setting unit that, in accordance with whether or not each of the outriggers overhang lengths is a maximum overhang length, sets a maximum RTL work range which is a range, within the permitted work range, in which at least crane work at a maximum rated total load can be carried out;
wherein, when a condition is not fulfilled in that the overhang angles of the four outriggers all be the reference overhang angle, or a condition is not fulfilled in that the overhang angles of at least two outriggers be the reference overhang angle, the overhang lengths be the maximum overhang length, and these two outriggers be located adjacent at the front and rear or the left and right of the traveling body,
the permitted work range setting unit sets the entire crane work area to a non-permitted work range in which crane work cannot be carried out, without setting the permitted work range.
3. The safety device for the mobile crane according to claim 2 ,
wherein, where
the outrigger on a right rear side of the traveling body is referred to as a first outrigger,
the outrigger on a right front side of the traveling body is referred to as a second outrigger,
the outrigger on a left rear side of the traveling body is referred to as a fourth outrigger, and
the outrigger on the left front side of the traveling body is referred to as a third outrigger,
the reference overhang angle of the first and fourth outriggers is a first overhang angle less than 90 degrees, respectively to left and right relative to the traveling body longitudinal direction, and
the reference overhang angle of the second and third outriggers is a second overhang angle less than 90 degrees, respectively to the left and right relative to the traveling body longitudinal direction.
4. The safety device for the mobile crane according to claim 3 ,
wherein the crane work area is sectioned into eight turning ranges as follows:
a front turning range over an angle less than 90 degrees to the left and right, centered about a forward line A extending forward along the traveling body from the turning center;
a right turning range over an angle less than 90 degrees forward and backward, centered about a rightward line D extending rightward along the traveling body from the turning center;
a rear turning range over an angle less than 90 degrees to the left and right, centered about a rearward line G extending rearward along the traveling body from the turning center;
a left turning range over an angle less than 90 degrees forward and backward, centered about a leftward line J extending leftward along the traveling body from the turning center;
a forward-right turning range between the front turning range and the right turning range;
a rearward-right turning range between the rear turning range and the right turning range;
a rearward-left turning range between the rear turning range and the left turning range; and
a forward-left turning range between the left turning range and the front turning range; and
wherein the load-specific work range setting unit:
sets at least the right turning range to the maximum RTL work range when the second and first outriggers at the front and rear on the right side are in the maximum overhang length;
sets at least the rear turning range to the maximum RTL work range when the fourth and first outriggers at the left and right on the rear side are in the maximum overhang length;
sets at least the left turning range to the maximum RTL work range when the fourth and third outriggers at the front and rear on the left side are in the maximum overhang length; and
sets at least the front turning range to the maximum RTL work range when the third and second outriggers at the left and right on the front side are in the maximum overhang s length.
5. The safety device for the mobile crane according to claim 4 ,
wherein the load-specific work range setting unit sets the minimum RTL work range, in which the crane work can be carried out at a minimum rated total load, to the maximum RTL work range.
6. The safety device for the mobile crane according to claim 4 ,
wherein the load-specific work range setting unit sets a range other than the maximum RTL work range in the permitted work range, to the minimum RTL work range in which the crane work can be carried out at a minimum rated total load.
7. The safety device for the mobile crane according to claim 6 ,
wherein the first to fourth outriggers are capable of changing overhang lengths thereof to at least the maximum overhang length and a minimum overhang length; and
the permitted work range setting unit sets the permitted work range, and the load-specific work range setting unit sets the maximum RTL work range and the minimum RTL work range as defined in the following table A;
TABLE A
PATTERNS OF OUTRIGGER OVERHANG STATE
SPECIFICS OF RESTRICTING OPERATIONS
OR1
OR2
OR3
OR4
PERMITTED-WORK
MAXIMUM RTL
MINIMUM RTL
{circle around (1)}
{circle around (2)}
{circle around (3)}
{circle around (4)}
RANGE
WORK RANGE
WORK RANGE
1
MAX
MAX
MAX
MAX
ALL
ALL
NONE
2
min
min
min
min
ALL
NONE
ALL
3
MAX
MAX
min
min
ALL
CDE
RANGE
4
MAX
MAX
MAX
min
ALL
LABCDE
OTHER THAN
5
MAX
MAX
min
multi
ABCDEFG
CDE
MAXIMUM RTL WORK
6
MAX
MAX
multi
min
ABCDEFG
RANGE IN
7
MAX
MAX
multi
multi
ABCDEFG
PERMITTED-WORK
8
MAX
MAX
MAX
multi
JKLABCDEFG
LABCDE
RANGE
9
min
MAX
MAX
min
ALL
LAB
10
min
MAX
MAX
MAX
ALL
IJKLAB
11
multi
MAX
MAX
min
GHIJKLABCD
LAB
12
min
MAX
MAX
multi
JKLABCDEFG
13
multi
MAX
MAX
multi
JKLABCD
14
multi
MAX
MAX
MAX
GHIJKLABCD
IJKLAB
15
min
min
MAX
MAX
ALL
IJK
16
MAX
min
MAX
MAX
ALL
FGHIJK
17
min
multi
MAX
MAX
GHIJKLA
IJK
18
multi
min
MAX
MAX
GHIJKLA
19
multi
multi
MAX
MAX
GHIJKLA
20
MAX
multi
MAX
MAX
DEFGHIJKLA
FGHIJK
21
MAX
min
min
MAX
ALL
FGH
22
MAX
MAX
min
MAX
ALL
CDEFGH
23
MAX
min
multi
MAX
ABCDEFGHIJ
FGH
24
MAX
multi
min
MAX
DEFGHIJKLA
25
MAX
multi
multi
MAX
DEFGHIJ
26
MAX
MAX
multi
MAX
ABCDEFGHIJ
CDEFGH
where
OR 1 : the first outrigger,
OR 2 : the second outrigger,
OR 3 : the third outrigger,
OR 4 : the fourth outrigger,
MAX: an outrigger in an overhang state in which the overhang length is the maximum overhang length and the overhang angle is the reference overhang angle,
min: an outrigger in an overhang state in which the overhang length is other than the maximum overhang length and the overhang angle is the reference overhang angle,
multi: an outrigger in an overhang state in which the overhang angle is other than the reference overhang angle with the overhang length irrelevant,
LAB: the front turning range over angles less than 90 degrees to the left and right, centered about the forward line A extending to the front of the traveling body from the turning center,
CDE: the right turning range over angles less than 90 degrees to the front and rear, centered about a rightward line D extending to the right of the traveling body from the turning center,
FGH: the rear turning range over angles less than 90 degrees to the left and right, centered about the rearward line G extending to the rear of the traveling body from the turning center,
IJK: the left turning range over angles less than 90 degrees to the front and rear, centered about a leftward line J extending to the left of the traveling body from the turning center,
BC: the forward-right turning range between the front turning range and the right turning range,
EF: the rearward-right turning range between the rear turning range and the right turning range,
HI: the rearward-left turning range between the rear turning range and the left turning range
KL: the forward-left turning range between the left turning range and the front turning range,
Maximum RTL work range: the range in which crane work is possible at the maximum rated total load, and
Minimum RTL work range: the range in which crane work is possible at the minimum rated total load.
8. A safety device for a mobile crane, which restricts crane work in accordance with respective overhang states of four outriggers of which both overhang length and overhang angle can be varied, the outriggers being attached to a traveling body equipped with a crane boom, the safety device comprising:
a permitted work range setting unit that, in accordance with whether or not each of the outrigger overhang angles is a reference overhang angle, sets a permitted work range in which crane work can be carried out within a crane work area having a maximum work radius centered around a turning center of a crane boom;
a load-specific work range setting unit that, in accordance with whether or not each of the outriggers overhang lengths is a maximum overhang length, sets a maximum RTL work range which is a range, within the permitted work range, in which at least crane work at a maximum rated total load can be carried out;
an overhang length detection unit for detecting the overhang lengths of the respective outriggers;
an overhang angle detection unit for detecting the overhang angles of the respective outriggers;
a turning angle detection unit for detecting a turning angle position of the crane boom;
an operation restriction unit for restricting operation of the crane boom based on settings by the permitted work range setting unit and the load-specific work range setting unit; and
a display device having a display screen for displaying overhang states of the respective outriggers and operation restriction contents by the operation restriction unit;
wherein the display device has first to fourth outrigger overhang lamps for displaying overhang states of the first to fourth outriggers on the display screen;
wherein each of the first to fourth outrigger overhang lamps is capable of illuminating in a first form, a second form, and a third form; and
wherein the first form indicates that the displayed outrigger is in an overhang state in which the overhang length is the maximum overhang length and the overhang angle is the reference overhang angle,
the second form indicates that the displayed outrigger is in an overhang state in which the overhang angle is the reference overhang angle and the overhang length is not the maximum overhang length, and
the third form indicates that the displayed outrigger is in an overhang state in which the overhang angle is other than the reference overhang angle.
9. The safety device for the mobile crane according to claim 8 ,
wherein the first form is a continuous lighting in a first color, the second form is a continuous lighting in a second color, and the third form is a continuous lighting in a third color;
wherein, in the second form, a flashing of the second color indicates that turning of the crane boom has been stopped by turning restriction in a direction of the outrigger to be designated; and
wherein, in the third form, a flashing of the third color indicates that the turning of the crane boom has been stopped by turning restriction in a direction of the outrigger to be designated.
10. A safety device for a mobile crane, which restricts crane work in accordance with respective overhang states of four outriggers of which both overhang length and overhang angle can be varied, the outriggers being attached to a traveling body equipped with a crane boom, the safety device comprising:
a permitted work range setting unit that, in accordance with whether or not each of the outrigger overhang angles is a reference overhang angle, sets a permitted work range in which crane work can be carried out within a crane work area having a maximum work radius centered around a turning center of a crane boom;
a load-specific work range setting unit that, in accordance with whether or not each of the outriggers overhang lengths is a maximum overhang length, sets a maximum RTL work range which is a range, within the permitted work range, in which at least crane work at a maximum rated total load can be carried out;
an overhang length detection unit for detecting the overhang lengths of the respective outriggers;
an overhang angle detection unit for detecting the overhang angles of the respective outriggers; and
a turning angle detection unit for detecting a turning angle position of the crane boom;
wherein the turning angle detection unit has a first potentiometer that detects a rotational angle position of the crane boom in one 180 degree segment, and a second potentiometer that detects the rotational angle position in the other 180 degree segment; and
wherein an angle position where detection signals switch between the first and second potentiometers is set so as to not coincide with either the turning angle position stipulating the permitted work range set by the permitted work range setting unit, or the turning angle position stipulating the maximum RTL work range set by the load-specific work range setting unit.