Excavating – Ditcher – Condition responsive
Reexamination Certificate
2002-09-26
2004-05-11
Novosad, Christopher J. (Department: 3671)
Excavating
Ditcher
Condition responsive
C037S414000, C701S050000
Reexamination Certificate
active
06732458
ABSTRACT:
TECHNICAL FIELD
This invention relates to an automatically operated shovel, and more specifically to an automatically operated shovel permitting an automated adjustment of a digging path in accordance with a magnitude of digging resistance during excavation of a quarried material including rock and/or stone having high digging resistance, and also to a rock crushing system making use of the automatically operated shovel.
BACKGROUND ART
Power shovels are known as a representative example of construction machines for many years. In recent years, power shovels are designed to perform work by automated operation when the work consists of repetitions of a series of simple work ranging from digging to hauling. To permit automatic operation of a power shovel, however, there are a variety of problems which must be solved. For example, when a bucket comes into full contact with rock, stone or the like in the course of digging work by the power shovel and becomes no longer possible to perform a desired operation, a skilled operator infers such a situation and performs an evasive operation so that the work can be smoothly continued. To allow an automatically operated shovel to perform this, certain measures are needed.
As a conventional measure for the solution of such a problem during digging work, JP 61-9453 B discloses a technique that overload detection sensors are arranged to detect overloads applied to an arm and a bucket and, when an overload is detected, a boom is raised slightly to reduce the overload for the continuation of automated digging. On the other hand, JP 4-350220 A discloses a technique that, when at least one of detection values from pressure sensors attached to cylinders for actuating a boom, an arm and a bucket reaches a predetermined value or greater and at least one of operation speeds determined from angle sensors attached to the boom, arm and bucket becomes equal to or smaller than a predetermined value, both in the course of digging, an overload is determined and a digging path is shifted to avoid an obstacle to the digging work.
Automation of rock crushing work at quarries is also under way in recent years, and a technique on an automated rock crushing plant is disclosed in JP 9-195321 A. In this automated rock crushing plant, quarried rock heaved by a bulldozer is bucketed by a power shovel and hauled into a mobile crusher, where gravel is then produced. Further, the bulldozer operated by an operator is provided with a control device for automatically operating and controlling the power shovel and mobile crusher, and at a position remote from the power shovel, another control device is also arranged to automatically operate and control the power shovel and mobile crusher.
However, the technique of JP 61-9453 B requires the overload detection sensors in addition to position detecting sensors for detecting positions of individual articulations and moreover, involves a problem that a processing load for performing automated operation is significant. The technique of JP 4-350220 A, on the other hand, requires a variety of sensors, and also needs computation based on data detected by the sensors, resulting in applications of increased computation loads to the control device which the automatically operated shovel is provided with. Further, when the automatically operated shovel is operated slowly, its operation speed may become so low that it may be hardly distinguishable from a low speed at the time of overloading, leading to a potential problem of a false detection of an overload. Further, the pressure of each cylinder increases when the bucket comes into contact with rock, stone or the like. If the rock, stone or the like begins to move by a resulting shock, the pressure drops. This pressure drop may also lead to a potential problem of a false detection. In addition, with methods for determining an overload from such pressure sensors and operation speeds, it is practically difficult to determine the level of a pressure value and that of an operation speed both of which indicate an overload.
In the rock crushing plant disclosed in JP 9-195321 A, the power shovel is set such that quarried rock heaved by the bulldozer can be bucketed in an order stored in advance. To permit efficient bucketing of quarried rock by the power shovel, it is necessary to operate the bulldozer such that the quarried rock is heaved to an operating range of the power shovel. At this time, an operator on the bulldozer has to control the bulldozer by paying attention to the distance between the bulldozer and the power shovel so that the bulldozer can be kept out of contact with a front part of the power shovel which is performing the bucketing of quarried rock. Further, while the bucketing of quarried rock is performed by the power shovel, it is necessary to suspend the heaving operation of quarried rock to the operating range of the power shovel by the bulldozer in order to avoid any contact to the front part of the power shovel. A further problem also exists in that, when the amount of quarried rock becomes small within the operating range of the power shovel, the operation of the power shovel has to be suspended to heave quarried rock by the bulldozer. The rock crushing plant is therefore accompanied by problems that a rock crushing operation cannot be performed stably with good efficiency.
With the above-described various problems in view, an object of the present invention is to provide an automatically operated shovel which can avoid obstacles during digging by a simple method without needing a special system for the detection of an overloaded state during the digging and also to improve the efficiency of work in a rock crushing system making use of the automatically operated shovel.
DISCLOSURE OF THE INVENTION
To achieve the above-described object, the invention provides an automatically operated shovel including a power shovel and an automatic operation controller arranged on the power shovel for making the power shovel reproduce a series of taught operations ranging from digging to hauling, the automatic operation controller is provided with a positioning determination means for determining whether or not the power shovel has reached within a positioning range predetermined based on corresponding one of positioning accuracies set for individual taught positions of the power shovel; and, when the power shovel is determined to have reached within the predetermined positioning range, the automatic operation controller outputs next one of the taught positions as a target position.
In an embodiment, during reproducing operations from an initiation of the digging to an end of the digging, the automatic operation controller outputs, subsequent to outputting one of the taught positions as a target position, a target position based on next one of the taught positions without performing a determination by the positioning determination means.
In another embodiment, in an automatically operated shovel including a power shovel provided with solenoid-operated directional control valves for operating hydraulic cylinders, which are adapted to actuate at least a boom, an arm and a bucket, and a hydraulic motor for driving a swivel superstructure and also with angle detector for detecting angles between the swivel superstructure and the boom, between the boom and the arm and between the arm and the bucket, respectively, a taught position output means for successively reading and outputting taught position data which have been taught and stored, a servo preprocessing means for being inputted with the taught position data and outputting target position data with position data interpolated between the taught position data to allow the power shovel to operate smoothly, and a servo control means for being inputted with the target position data and outputting control signals to the solenoid-operated directional control valves to control the power shovel to a target position, wherein the automatic operation controller is provided with a positioning determination means for determining whether or not the p
Hashimoto Akira
Ishibashi Hideto
Kurenuma Toru
Nagano Yoshiyuki
Sugawara Kazuhiro
Hitachi Construction Machinery Co. Ltd.
Novosad Christopher J.
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