Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Construction or agricultural-type vehicle
Reexamination Certificate
1998-09-03
2001-05-08
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Construction or agricultural-type vehicle
C037S348000, C091S419000, C212S280000
Reexamination Certificate
active
06230090
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an interference prevention system for a 2-piece boom type hydraulic excavator, and more particularly to an interference prevention system for a 2-piece boom type hydraulic excavator, which operates to restrict movement of a work front when a predetermined position of the work front comes close to an excavator body.
1. Background Art
A work front of a hydraulic excavator is made up of front members such as a boom and an arm, which are vertically movable, with a working appliance, e.g., a bucket, attached to a fore end of the arm. The boom of the work front is bent at a certain angle and is usually constituted by a single mono-boom. In some hydraulic excavators, a boom is divided into two parts, i.e., a first boom and a second boom. These hydraulic excavators are called 2-piece boom type hydraulic excavators.
In a 2-piece boom type hydraulic excavator, when manipulating the front members, such as the first boom, the second boom and the arm, through respective control levers, the operator can freely change an angle formed between the first boom and the second boom; hence there is a risk that the bucket may interfere with the excavator body, in particular an operating room (cab), depending on the angle formed between the first boom and the second boom. For that reason, an interference prevention system for preventing such interference is proposed in JP, A, 2-308018.
In the interference prevention system proposed in JP, A, 2-308018, potentiometers are provided at pivotally articulated portions of the first boom, the second boom and the arm to detect relative angles of the respective articulations, and an arm end position is calculated based on outputs from the potentiometers. When the calculated arm end position enters a preset danger area, a signal is output to actuate an alarm device. Also, when the calculated arm end position enters the preset danger area, an interference prevention controller outputs a signal to shift a switching valve, which is installed between an actuator for operating each front member and a control valve, to an off-position, thereby automatically stopping movement of the front member under operation.
2. Disclosure of the Invention
In the related art disclosed in JP, A, 2-308018, as described above, when the arm end enters the danger area, the movement of the front members is restricted so as to stop. Such control of stopping the front members is however disadvantageous in that when the operator performs work near the cab, it is difficult to continuously smoothly carry out the work that requires the work front to be moved in a direction toward the operator (cab), e.g., excavating and earth-releasing, thus resulting in a remarkable reduction in working efficiency.
An object of the present invention is to provide an interference prevention system for a 2-piece boom type hydraulic excavator with which such work as requiring a work front to be moved in a direction toward the operator is continuously smoothly performed and working efficiency is improved.
(1) To achieve the above object, the present invention provides an interference prevention system for a 2-piece boom type hydraulic excavator, the interference prevention system being installed in a 2-piece boom type hydraulic excavator comprising an excavator body, a work front mounted on the excavator body and having a plurality of front members including first and second booms and an arm which are vertically rotatable, a first boom cylinder for driving the first boom, a second boom cylinder for driving the second boom, an arm cylinder for driving the arm, a first-boom flow control valve for controlling a flow rate of a hydraulic fluid supplied to the first boom cylinder in accordance with an operation signal from first-boom operating means, a second-boom flow control valve for controlling a flow rate of a hydraulic fluid supplied to the second boom cylinder in accordance with an operation signal from second-boom operating means, and an arm flow control valve for controlling a flow rate of a hydraulic fluid supplied to the arm cylinder in accordance with an operation signal from arm operating means, the interference prevention system serving to restrict movement of the work front when a predetermined position of the work front comes close to the excavator body, wherein the interference prevention system comprises attitude detecting means for detecting an attitude of the work front, and control means for receiving detection signals from the attitude detecting means and, when the predetermined position of the work front comes close to the excavator body, outputting a command signal to the second-boom flow control valve so that the second boom is moved in a dumping direction.
With the present invention thus constructed, since the second boom is moved in the dumping direction when the predetermined position of the work front comes close to the excavator body, the work front is prevented from interfering with the excavator body or a cab without being stopped, and such work as requiring the work front to be moved toward the operator (cab) can be continuously, smoothly performed.
Also, since the above-mentioned control is made by moving the second boom in the dumping direction, which is less frequently employed in actual work, rather than the arm, the interference avoidance control can be achieved allowing the operator to feel less awkward during the operation.
(2) In the above (1), preferably, when the first boom is operated in a rising direction by the operating means for the first boom, the control means makes control to move the second boom in the dumping direction while continuing to raise the first boom.
With this feature, when the predetermined position of the work front comes close to the excavator body, the predetermined position of the work front is controlled to move while going around the excavator body (cab) with a combination of the first-boom raising operation and the second-boom dumping operation. As a result, such work as requiring the work front to be moved toward the operator (cab) can be continuously smoothly performed while avoiding interference between the work front and the excavator body.
(3) In the above (2), preferably, the control means receives an operation signal in the first-boom raising direction output from the operating means for the first boom, and modifies the operation signal in the first-boom raising direction such that first-boom raising operation is slowed down as the predetermined position of the work front comes closer to the excavator body, and thereafter the first-boom raising operation is continued at a slowed-down speed.
With this feature, since the first-boom raising operation is slowed down when the predetermined position of the work front comes close to the excavator body, the second boom cylinder can be supplied with the hydraulic fluid at a sufficient flow rate even when there is a limit in maximum capacity of a hydraulic pump. Accordingly, the second boom can be quickly dumped and the work front is surely prevented from interfering with the excavator body.
Also, since the first-boom raising operation is slowed down, a distance left between the predetermined position of the work front and the excavator body when the former comes close to the latter is suppressed, and therefore interference between the work front and the excavator body is surely prevented with the dumping of the second boom.
(4) In the above (2), preferably, the control means receives an operation signal in a second-boom crowding direction output from the operating means for the second boom and an operation signal in an arm crowding direction output from the operating means for the arm, and modifies the operation signal in the second-boom crowding direction and the operation signal in the arm crowding direction such that when the first boom is not moved in the rising direction, the work front is slowed down as the predetermined position of the work front comes closer to the excavator body and thereafter the work front is stopped.
With this feature, in w
Kajita Yusuke
Sunamura Kazuhiro
Takahashi Ei
Cuchlinski Jr. William A.
Hitachi Construction Machinery Co. Ltd.
Mattingly, Stanger & Malur
Pipala Edward
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