Wheel loader

Patent metadata

Field	Value
Publication number	US-9037358-B2
Application number	US-201113574724-A
Country	US
Kind code	B2
Filing date	Dec 21, 2011
Priority date	Dec 24, 2010
Publication date	May 19, 2015
Grant date	May 19, 2015

Abstract

An engine control device of the wheel loader includes a travelling state detecting unit for detecting a travelling state of the wheel loader, a mode switching determining unit, an acceleration speed detecting unit and a switching time controlling unit. The acceleration speed detecting unit detects the acceleration speed of the wheel loader when the mode switching determining unit determines that it is required to switch between the engine output modes from a low output mode to a high output mode based on a detection result of the travelling state detecting unit. The switching time control unit controls the switching time from start to end of mode switching to be: a first time when the acceleration speed detected by the acceleration speed detecting unit is either 0 or negative; and a second time greater than the first time when the detected acceleration speed is positive.

First claim

The invention claimed is:

1. A wheel loader having a low output mode and a high output mode as engine output modes, the wheel loader comprising:
an engine;
a transmission having an output shaft;
an output shaft rotational speed sensor configured and arranged to detect a rotational speed of the output shaft;
a driving wheel;
a power transmission device configured to transmit driving force from the engine to the driving wheel;
a work implement configured to be driven by the driving force from the engine; and
an engine control device configured to execute a mode switching control of switching between the low output mode and the high output mode, the engine control device being configured and arranged to receive a detection signal from the output shaft rotational speed sensor,
the engine control device comprising a microcomputer programmed to include
a travelling state detecting unit configured to detect if the wheel loader is in a hill-climb travelling state;
a mode switching determining unit configured to determine that it is required to switch from the low output mode to the high output mode upon the travelling state detecting unit detecting that the wheel loader is in the hill-climb traveling state;
an acceleration detecting unit configured to detect an acceleration of the wheel loader upon the mode switching determining unit determining that it is required to switch between the engine output modes due to the wheel loader being in the hill-climb travelling state; and
a switching time controlling unit configured to set a mode switching time in accordance with the acceleration detected by the acceleration detecting unit, the switching time controlling unit setting the mode switching time to
a first time if the acceleration detected by the acceleration detecting unit is either 0 or negative, indicating the wheel loader has shifted from flatland travelling to hill-climb traveling, and
a second time greater than the first time if the acceleration detected by the acceleration detecting unit is positive, indicating that the wheel loader has started moving on a hill from a stopped state,

the engine control device being configured to execute the mode switching control such that a time from start to end of the mode switching control is equal to the mode switching time set by the switching time controlling unit upon the traveling state detecting unit detecting that the wheel loader is in a hill-climb travelling state.

2. A wheel loader having a low output mode and a high output mode as engine output modes, the wheel loader comprising:
an engine;
a transmission having an output shaft;
an output shaft rotational speed sensor configured and arranged to detect a rotational speed of the output shaft;
a driving wheel;
a power transmission device configured to transmit driving force from the engine to the driving wheel;
a work implement configured to be driven by the driving force from the engine; and
an engine control device configured to execute a mode switching control of switching between the low output mode and the high output mode, the engine control device being configured and arranged to receive a detection signal from the output shaft rotational speed sensor,
the engine control device comprising a microcomputer programmed to include
a travelling state detecting unit configured to detect if the wheel loader is in a hill-climb travelling state;
a mode switching determining unit configured to determine that it is required to switch from the low output mode to the high output mode upon the travelling state detecting unit detecting that the wheel loader is in the hill-climb traveling state;
an acceleration detecting unit configured to detect an acceleration of the wheel loader upon the mode switching determining unit determining that it is required to switch between the engine output modes due to the wheel loader being in the hill-climb travelling state; and
an output torque change rate controlling unit configured to set a change rate of an output torque of the engine in accordance with the acceleration detected by the acceleration detecting unit, the output torque change rate controlling unit setting the change rate to
a first change rate if the acceleration detected by the acceleration detecting unit is either 0 or negative, indicating the wheel loader has shifted from flatland travelling to hill-climb traveling, and
a second change rate less than the first change rate if the acceleration detected by the acceleration detecting unit is positive, indicating that the wheel loader has started moving on a hill from a stopped state,

the engine control device being configured to execute the mode switching control such that the output torque of the engine changes at the change rate set by the output torque change rate controlling unit from start to end of the mode switching control upon the traveling state detecting unit detecting that the wheel loader is in a hill-climb travelling state.

3. The wheel loader recited in claim 1 , wherein
the travelling state detecting unit is configured to determine that the wheel loader is in the hill-climb travelling state upon the following conditions being satisfied: a condition that a vehicle speed is less than or equal to a predetermined value; a condition that a throttle opening degree has been kept greater than or equal to a preliminarily set threshold opening degree for a predetermined period of time or greater; and a condition that a brake operation is not being performed.

4. The wheel loader recited in claim 3 , wherein
the conditions to be satisfied for the travelling state detecting unit to determine that the wheel loader is in the hill-climb travelling state further include a condition that the acceleration is less than or equal to a predetermined value.

5. The wheel loader recited in claim 3 , wherein
the travelling state detecting unit is further configured to detect that the wheel loader has shifted from the hill-climb travelling state to a hill-climb released state, the hill-climb released state being different from the hill-climb traveling state, and
the mode switching determining unit is configured to switch from the high output mode to the low output mode when the wheel loader is detected to be in the hill-climb released state.

6. The wheel loader recited in claim 5 , wherein
the travelling state detecting unit is configured to detect that the wheel loader is in the hill-climb released state upon at least one of the following conditions being satisfied: a condition that a throttle opening degree becomes less than the threshold opening degree; and a condition that a brake operation is performed.

Assignees

• Ota Toshuki
• Matsuyama Nobuo
• Komatsu Mfg Co Ltd

Inventors

• Ota Toshiyuki
• Matsuyama Nobuo

Classifications

• F02D41/10

  for acceleration · CPC title

• F02D11/105 Primary

  characterised by the function converting demand to actuation, e.g. a map indicating relations between an accelerator pedal position and throttle valve opening or target engine torque · CPC title

• E02F9/2066

  of the type combustion engines · CPC title

• F02D45/00

  Electrical control not provided for in groups F02D41/00 - F02D43/00 · CPC title

• B60W30/182 Primary

  Selecting between different operative modes, e.g. comfort and performance modes · CPC title