Boom driving system for hybrid excavator and control method therefor

• US 9,732,501 B2
• Filed: 01/28/2013
• Issued: 08/15/2017
• Est. Priority Date: 01/30/2012
• Status: Active Grant

• Current Assignee: HD Hyundai Infracore Co., Ltd.
• Original Assignee: Doosan Infracore Company Limited
• Inventors: Kang, Byung Il
• Primary Examiner(s): Keasel, Eric
• Assistant Examiner(s): Wiblin, Matthew
• Application Number:
  US14/375,185
• Publication Number:
  US 20150267381A1
• Time in Patent Office: 1,660 Days
• CPC Class Codes: E02F 9/2075 of the hybrid type for vehicles in general B60W20/00
• CPC Class Codes: E02F 9/22 Hydraulic or pneumatic drives for dipper or bucket arm position control E02F3/43, for blade position control for graders E02F3/844; for turntables E02F9/121; for fork-lift trucks B66F9/22
• CPC Class Codes: E02F 9/2203 Arrangements for controlling the attitude of actuators, e.g. speed, floating function
• CPC Class Codes: E02F 9/2221 Control of flow rate; Load sensing arrangements E02F9/2203 take precedence over E02F9/2221
• CPC Class Codes: E02F 9/2235 including an electronic controller
• CPC Class Codes: E02F 9/2246 Control of prime movers, e.g. depending on the hydraulic load of work tools
• CPC Class Codes: E02F 9/2289 Closed circuit
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump

Abstract

The present disclosure relates to a boom driving system for a hybrid excavator and a control method therefor, and more particularly, to a boom driving system for a hybrid excavator, which drives a hydraulic pump motor so as to move a boom upward and downward, and collects regenerative power of the boom using an electric motor so as to improve fuel efficiency, and a control method for the boom driving system. Provided in exemplary embodiments of the present disclosure is a boom driving system for a hybrid excavator and a control method therefor, which may allow an electric motor generator to normally produce electricity by allowing retraction speed and force of the boom actuator to be controlled to a target speed when a boom is moved downward.

Claims

1. A boom driving system for a hybrid excavator, comprising:

an electric motor which is operated as a motor or a generator;

an electric energy storage device which stores electricity produced by the electric motor;

a hydraulic pump motor which is operated by the electric motor and supplies a hydraulic fluid to a boom actuator;

a boom control valve which configures a closed circuit so as to selectively connect or disconnect a discharge line of the hydraulic pump motor and an inlet line of the hydraulic pump motor to/from a head side or a rod side of a boom cylinder that operates the boom actuator;

a first control valve which connects the inlet line to a drain tank;

a second control valve which connects the discharge line to the drain tank, and of which the opening area is controlled to be changed according to a size of torque that is applied to the electric motor when the boom actuator performs a downward operation; and

a control unit which controls the electric motor, the hydraulic pump motor, the boom control valve, and the first and second control valves,

wherein the control unit determines whether operating torque of the electric motor has a plus value or a minus value, and controls the second control valve to be maximally opened when the operating torque has the minus value and controls the opening area of the second control valve to be reduced when the operating torque has the plus value.

2. The boom driving system of claim 1, wherein the first control valve is connected when the boom actuator performs an upward operation, and shut off when the boom actuator performs the downward operation, and the second control valve is shut off when the boom actuator performs the upward operation, and connected when the boom actuator performs the downward operation.