Working Machine
AssigneeCaterpillar SARL
InventorsShogo Tada, Masafumi Ohkubo, Yozo Nakamoto
Life of this patent
Estimating the term…
Abstract
A work machine has a work device mounted on a machine body including a fluid pressure motor for travelling. A controller reduces engine speed to be lower than rated engine speed during normal working mode. The controller controls engine speed so as to obtain a pump flow rate in accordance with a target travelling speed during travelling low-load mode when engine load is lower than a threshold. The controller controls both the engine speed and output torque for pump control so that the engine output becomes maximum in travelling high-load mode when the engine load is higher than the threshold.
Claims14
A working machine comprising:
- a vehicle body that includes a traveling hydraulic pressure motor and travels using the traveling hydraulic pressure motor;
- a working unit that includes a working hydraulic pressure actuator and is mounted on the vehicle body operated by the working hydraulic pressure actuator;
- an engine that is mounted on the vehicle body;
- a variable displacement hydraulic pressure pump that is driven by the engine so as to supply an operating fluid to the traveling hydraulic pressure motor and the working hydraulic pressure actuator;
- and
- a controller that decreases an engine rotation speed to be lower than a rated. rotation speed during a normal operation state in a state where the traveling hydraulic pressure motor is stopped, that controls the engine rotation speed so that a. pump flow rate is adjusted. corresponding to a target traveling speed during a light load state where an engine load generated when operating the traveling hydraulic pressure motor is lower than a threshold, and that controls the engine rotation speed and a pump control output torque so that engine output power is increased from that during the normal operation state and the light load, during a heavy load state where the engine load is higher than the threshold.
The working machine according to claim 1, wherein
- the traveling hydraulic pressure motor is provided on each of left and right sides of the vehicle body,
- a plurality of variable displacement hydraulic pressure pumps are provided so as to correspond to these traveling hydraulic pressure motors and include a pump swash plate as displacement varying means, and
- the controller maintains a pump swash plate of each hydraulic pressure pump during traveling at a maximum swash angle and variably controls the engine rotation speed.
The working machine according to claim 3, wherein
- the controller has:
- a first threshold for changing the engine rotation speed from a light load traveling mode engine rotation speed to a heavy load traveling mode engine rotation speed when the engine load during traveling increases;
- and
- a second threshold., which is lower than the first threshold, for controlling to return the engine rotation speed from the heavy load traveling mode engine rotation speed to the light load traveling mode engine rotation speed when the engine load decreases.
The working machine according to claim 3, wherein
- the engine load is determined based on at least one of measured amounts of a pump load pressure discharged from the hydraulic pressure pump, a traveling load pressure applied to the traveling hydraulic pressure motor, a fuel discharge amount of the engine, and a cylinder internal pressure of the engine, or the fuel discharge amount and the rotation speed of the engine.
Dependencies are inferred from the claim text.