Construction machinery

• US 20040222000A1
• Filed: 09/10/2003
• Published: 11/11/2004
• Est. Priority Date: 09/11/2002
• Status: Active Grant

• Current Assignee: Komatsu Ltd.
• Original Assignee: Komatsu Ltd.
• Inventors: Ohtsukasa, Naritosi
• Granted Patent: US 7,143,859 B2
• Time in Patent Office: Days
• US Class Current: 172/2
• CPC Class Codes: E02F 9/2075 of the hybrid type for vehicles in general B60W20/00
• CPC Class Codes: E02F 9/2217 with energy recovery arrangements, e.g. using accumulators, flywheels
• CPC Class Codes: F02B 41/00 Engines characterised by special means for improving conversion of heat or pressure energy into mechanical power
• CPC Class Codes: F02B 63/06 for pumps
• CPC Class Codes: F02B 75/02 Engines characterised by their cycles, e.g. six-stroke
• CPC Class Codes: Y02P 60/14 Measures for saving energy, e.g. in green houses

Abstract

To provide construction machinery which is capable of improving fuel consumption rate of the engine and also capable of effectively utilizing surplus energy in the light-load mode (a mode where the engine torque at the intersection point of the iso-horsepower curve of the necessary horsepower and the governor characteristic curve of the engine is smaller than that of the rating output point of the engine). The construction machinery includes an engine, a hydraulic pump driven by the engine, and actuators driven by pressure oil supplied from the hydraulic pump. In the light-load mode where the engine torque at the intersection point of the iso-horsepower curve of the necessary horsepower and the governor characteristic curve of the engine is smaller than that of the rating output point of the engine, the number of revolutions of the engine is reduced while the engine torque is increased with respect to the intersection point, and the horsepower is made to exceed the iso-horsepower curve. With the surplus torque generated therefrom, a power generator is operated so as to generate electric power, which is charged in a power accumulation apparatus.

Claims

1. Construction machinery comprising:

an engine;

a hydraulic pump driven by the engine; and

an actuator driven by a pressure oil supplied from the hydraulic pump;

wherein

in a case of a load mode where an engine torque at an intersection point of an iso-horsepower curve of a necessary horsepower and a governor characteristic curve of the engine is smaller than that, of a rating output point of the engine, the number of revolutions of the engine is reduced and the engine torque is increased with reference to the intersection point, and the engine is allowed to run with a horsepower exceeding the iso-horsepower, and by a surplus torque generated therefrom, a power generator is operated so as to generate an electric power, which is accumulated in a power accumulation apparatus.

2. The construction machinery as claimed in claim 1, wherein in a case of a load mode where the iso-horsepower curve of the necessary horsepower and the governor characteristic curve of the engine do not generate an intersection point, the engine is driven at a point approximate to the rating output point while the power generator functioning as an electric motor is operated by the power accumulation apparatus so that assist running for assisting a shortage is performed.

3. The construction machinery as claimed in claim 1 or 2, wherein the power accumulation is performed with the number of revolutions by which the power generator is to be in a high efficiency state.

4. The construction machinery as claimed in claim 1 or 2, wherein the assist running is performed with the number of revolutions by which the power generator functioning as an electric motor is to be in a high efficiency state.