Process for automatically controlling actuators of excavator

• US 5,308,219 A
• Filed: 09/23/1991
• Issued: 05/03/1994
• Est. Priority Date: 09/29/1990
• Status: Expired due to Fees

• Current Assignee: Volvo Construction Equipment Korea Co., Ltd. (AB Volvo)
• Original Assignee: Samsung Heavy Industries Company Limited (Samsung Group)
• Inventors: Lee, Jin H., Jeong, Sang T., Kim, Jin T., Jo, Jang U., Kim, Ju K., Hoang, Bong D.
• Primary Examiner(s): Huppert, Michael S.
• Assistant Examiner(s): Underwood, Donald W.
• Application Number:
  US07/765,162
• Time in Patent Office: 953 Days
• Field of Search: 414/699, 414/687, 414/695.5, 414/700, 414/701, 414/708, 414/686, 91/508
• US Class Current: 414/695.5
• CPC Class Codes: E02F 3/435 for dipper-arms, backhoes or the like
• CPC Class Codes: E02F 9/2203 Arrangements for controlling the attitude of actuators, e.g. speed, floating function
• CPC Class Codes: G05B 19/042 using digital processors G05B19/05 takes precedence

Abstract

An automatic actuating system for actuators of excavator. The system of this invention automatically controls the bucket which is overloaded to be free from the overloaded state thereof, the bucket to maintain an angular position with respect to the absolute line of the ground surface so as to prevent the objects contained in the bucket from being dropped, the bucket cylinder and the boom cylinder to accomplish the desired surface finishing operation by handling for the dipper cylinder, actuators to limit the operational ranges thereof, optimal quantity of hydraulic fluid flow of the main hydraulic pumps for respective actuators, and the pre-running for the actuators.

Claims

1. A process for automatically controlling an apparatus for operating an excavator, said apparatus including a pair of adjustable volume hydraulic pumps with swash plates and swash plate control valves, an engine operably connected to the hydraulic pumps, a plurality of actuators operably connected to said hydraulic pumps, directional control valves operably connected to the pumps and actuators, and control levers and control pedals for generating electric control signals to control the actuators, the process comprising the steps of:

determining displacement values for said actuators to be actuated in response to electric control signals received from the control levers and control pedals for controlling said actuators;

determining a quantity of hydraulic fluid under pressure to be delivered from said hydraulic pumps to said actuators;

determining values representing the desired position of the directional control valves in order to cause the determined quantity of hydraulic fluid under pressure to be efficiently supplied to said actuators; and

limiting the output volume of said hydraulic pumps in accordance with the determined quantity of the hydraulic fluid to be supplied to said actuators and in accordance with the determined values of said directional control valves by outputting electric signals representing the limited pump output volumes of said hydraulic pumps to the swash plate control valves by way of an amplifier so as to control inclination angles of swash plates on said hydraulic pumps and in turn control the pump output volumes.

2. A process for automatically controlling an apparatus for operating an excavator, said apparatus including a pair of hydraulic pumps driven by an engine, a plurality of actuators actuated operably connected to said hydraulic pumps, directional control valves operably connected to the actuators, and control levers and control pedals for generating electric control signals to control the actuators, the process comprising the steps of:

determining handling values of the control levers and control pedals for controlling said actuators upon reception of electric control signals outputted from said control levers and control pedals;

calculating desired actuation speeds of said actuators in accordance with the determined handling values of said control levers and control pedals;

calculating actual actuation speeds of said actuators as sensed by displacement sensors on said actuators;

comparing the desired actuation speeds of said actuators with the actuation speeds of said actuators and determining whether said actuators are overloaded;

determining whether at least two actuators are being driven at the same time and whether at least two actuators are being driven by both of said hydraulic pumps, and further determining whether a control process for removing an overload condition on said actuators was performed in a previous operation of the excavator, still further determining whether controlled actuation speeds stored in the apparatus are equal to the actual actuation speeds of said actuators;

outputting electric signals representing the controlled actuation speeds of said actuators when it is determined that the actual actuation speeds of said actuators are equal to the controlled actuation speeds of said actuators, but calculating a quantity of hydraulic fluid under pressure to be supplied to said actuators in accordance with a given load on said actuators when it is determined that the actual actuation speeds of the actuators are not equal to the controlled actuation speeds of the actuators; and

outputting control signals to the directional control valves for controlling said directional control valves according to the quantity of hydraulic fluid to be supplied to said actuators.