HYBRID CONSTRUCTION MACHINE

• US 20140062096A1
• Filed: 09/03/2013
• Published: 03/06/2014
• Est. Priority Date: 09/06/2012
• Status: Active Grant

• Current Assignee: Kobelco Construction Machinery Company Limited (Kobe Steel Limited)
• Original Assignee: Kobelco Construction Machinery Company Limited (Kobe Steel Limited)
• Inventors: YAMASHITA, Koji
• Granted Patent: US 9,013,050 B2
• Time in Patent Office: Days
• US Class Current: 290/40.R
• CPC Class Codes: B60K 6/485 Motor-assist type
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/30 including control of auxiliary equipment, e.g. air-conditioning compressors or oil pumps
• CPC Class Codes: B60W 20/19 for achieving enhanced acceleration
• CPC Class Codes: B60W 2510/0657 Engine torque
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: E02F 9/2075 of the hybrid type for vehicles in general B60W20/00
• CPC Class Codes: H02P 9/00 Arrangements for controlling electric generators for the purpose of obtaining a desired output
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

Provided is a hybrid construction machine including: a hydraulic actuator; a hydraulic pump which discharges hydraulic fluid for driving the hydraulic actuator; a generator-motor which performs an electric generator action of generating electric power and an electric motor action of generating motive power; an engine connected to the hydraulic pump and the motor-generator; an electrical storage device; and a controller which causes the generator-motor to perform the electric generator action and charge the electrical storage device and causes the generator-motor to perform the electric motor action by electric power discharged from the electrical storage device to assist the engine. The controller causes the generator-motor to start the electric generator action when an engine output becomes equal to or greater than a predetermined engine lower limit output, and controls the electric generator action to keep the engine output no lower than the engine lower limit output.

Claims

1. A hybrid construction machine, comprising:

a hydraulic actuator;

a hydraulic pump which discharges hydraulic fluid for driving the hydraulic actuator;

a generator-motor which performs an electric generator action of generating electric power and performs an electric motor action of generating motive power;

an engine connected to the hydraulic pump and the motor-generator;

an electrical storage device; and

a controller which causes the generator-motor to perform the electric generator action to charge the electrical storage device and causes the generator-motor to perform the electric motor action by electric power discharged from the electrical storage device to assist the engine,

wherein the controller causes the generator-motor to start the electric generator action at the time when an output of the engine is equal to or greater than a predetermined engine lower limit output, and controls the electric generator action of the generator-motor so as to keep the engine output in a range of no lower than the engine lower limit output.

2. The hybrid construction machine according to claim 1, wherein the controller sets the engine lower limit output in accordance with a charge rate of the electrical storage device and sets the engine lower limit output to a lower value in accordance with the higher charge rate.

3. The hybrid construction machine according to claim 1, wherein the controller sets an engine upper limit output higher than the engine lower limit output, causes the generator-motor to perform the electric motor action when the engine output is greater than the engine upper limit output, and controls the electric motor action of the generator-motor so as to keep the engine output in a range of no more than the engine upper limit output.

4. The hybrid construction machine according to claim 3, wherein the controller sets an engine-output permissible increase as an amount of increase permissible in the engine output, and calculates the engine upper limit output by adding the engine output permissible increase to the engine lower limit output.

5. The hybrid construction machine according to claim 4, wherein the controller previously stores a map set in respect of a relationship between an engine speed, a fuel flow rate and the engine output permissible increase, and sets the engine output permissible increase to a larger value, for a fixed engine speed, in accordance with the smaller fuel flow rate, on the basis of the map.