Apparatus for controlling hydraulic cylinders of a power shovel

• US 5,116,186 A
• Filed: 03/30/1990
• Issued: 05/26/1992
• Est. Priority Date: 08/02/1988
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Komatsu Seisakusho, Mary Tom Hum
• Original Assignee: Kabushiki Kaisha Komatsu Seisakusho
• Inventors: Takasugi, Shinji, Hanamoto, Tadayuki
• Primary Examiner(s): Werner, Frank E.
• Assistant Examiner(s): Eller, James
• Application Number:
  US07/465,259
• Time in Patent Office: 788 Days
• Field of Search: 414/685, 414/694, 414/687, 414/697, 414/699, 414/700, 414/701, 414/706, 414/707, 414/708, 414/714, 37/DIG. 1
• US Class Current: 414/694
• CPC Class Codes: E02F 3/437 providing automatic sequences of movements, e.g. linear excavation, keeping dipper angle constant
• CPC Class Codes: E02F 3/438 Memorising movements for repetition, e.g. play-back capability

Abstract

A technique relating to automatic excavation by a power shovel is shown. An ideal reference locus of movement of a front edge of a bucket is approximated by a plurality of points, positions of the plurality of points and postures of the bucket at these points are previously set. If the start of automatic excavation is assigned by an operation pedal or the like, the position of the front edge of the bucket at the assigned moment is made a position to start excavation. The positions of the plurality of points set relative to a vehicle are calculated for each of excavation sections divided by the plurality of points according to the position to start excavation, and angles of rotation of respective working machines needed to move the front edge of the bucket to the calculated position and to set the bucket to the posture of the bucket set are calculated for each of the excavation sections, and the respective working machines are automatically driven making the calculated angles of rotation target angles of rotation for each excavation section. The bucket, an arm and a boom are thereby automatically controlled so that the front edge of the bucket moves along the ideal reference locus of movement set and the bucket has the ideal posture set by simple operations. Thus, it is intended to improve operation efficiency. After terminating excavation, dropping of load is reduced by automatically driving the bucket so that the bucket is always horizontally maintained in accordance with manual operations of the arm and boom.

Claims

1. A controlling device for a power shovel which includes a boom, an arm pivoted to the boom, a bucket pivoted to the arm, a boom cylinder for pivoting the boom, an arm cylinder for pivoting the arm, a bucket cylinder for pivoting the bucket, and a hydraulic pump for supplying pressurized oil into said boom cylinder, arm cylinder, and bucket cylinder, said controlling device being utilized for initially setting a reference locus of movement of a front edge of the bucket approximated by a plurality of points, for setting respective postures of the bucket when the front edge of the bucket is situated at the plurality of points, and for driving the bucket, arm, and boom so that the front edge of the bucket moves from an assigned position to start excavation along the plurality of points while the bucket maintains the initially set posture at the plurality of points, wherein said controlling device comprises:

pump pressure detection means for detecting the pump pressure of hydraulic oil supplied by the pump;

first control means comprising means for receiving detected values of an angle of the bucket, an angle of the arm and an angle of the boom at an assigned moment to start excavation, means for obtaining a position of the front edge of the bucket relative to a vehicle according to the detected values, means for calculating positions of the plurality of points set relative to the vehicle according to the obtained position to start excavation for the front edge of the bucket, means for obtaining an angle of rotation of the bucket, an angle of rotation of the arm and an angle of rotation of the boom needed to move the front edge of the bucket at said calculated position and to set the bucket to the posture of the bucket set for a proper point for each of excavation sections, and means for obtaining a distribution ratio of flow rates of pressurized oil to be supplied to the respective cylinders according to the angles of rotation for each of the excavation sections; and

second control means comprising means for setting a relationship between the pump pressure and the flow rate of the pump at the predetermined pressure, means for obtaining commands for flow rates for the respective cylinders by distributing the flow rate of the pump calculated from the relationship set and from the pump pressure detected by the pump pressure detection means in the distribution ratio obtained, means for outputting a command for a flow rate which is larger than the flow rate of the obtained command for a cylinder having the largest load, and for outputting the obtained commands for the flow rates for the other two cylinders; and

whereby the bucket arm and boom cylinders drive the bucket, arm and boom, respectively, according to the commands for flow rates output from said second control means.

2. A controlling device for a power shovel according to claim 1, wherein said second control means outputs a command for a flow rate fixed to the maximum value for the cylinder having the largest load.

3. A controlling device for a power shovel according to claim 1, wherein said second means includes a filter for outputting the calculated commands for flow rates reducing variations of the commands for flow rates with lime.

4. A controlling device for a power shovel according to claim 1, wherein said second control means makes the arm cylinder the cylinder having the largest load.