Automatic transmission device for wheel loader and wheel loader
AssigneeHitachi Construction Machinery Co., Ltd.
InventorsTetsuji Tanaka, Masami Higaki, Hirofumi Ouchi, Eiichi Sakai
Life of this patent
Estimating the term…
Abstract
An automatic transmission device for a wheel loader includes: a shift mechanism; a work detection device that detects that the wheel loader is performing an excavation work; and a shift control device that executes control so as to downshift a speed stage at the shift mechanism if the work detection device detects that the wheel loader is performing the excavation work.
Claims10
An automatic transmission device for a wheel loader, comprising:
- a shift mechanism connected to an engine via a torque converter;
- a vehicle speed detector that detects a speed of the wheel loader;
- a forward/reverse changeover switch that is operated to switch a traveling direction of the wheel loader from forward to reverse or vice versa;
- a decelerating state detection device that detects a decelerating state in which the wheel loader decelerates;
- a work detection device that detects that the wheel loader is performing an excavation work when a first predetermined period of time or more has elapsed since an operation of the forward/reverse changeover switch, a speed ratio at the torque converter calculated by dividing an output rotational speed by an input rotational speed decreases to a predetermined value or less, the deceleration state of the wheel loader continues over a second predetermined period of time, and the vehicle speed detector detects that the speed of the wheel loader is equal to or less than a predetermined speed;
- a shift control device that executes control so as to downshift a speed stage at the shift mechanism to speed 1 if the work detection device detects that the wheel loader is performing the excavation work.
An automatic transmission method for a wheel loader in which a shift mechanism of the wheel loader is connected to an engine of the wheel loader via a torque converter, comprising:
- detecting a speed of the wheel loader with a vehicle speed detector;
- detecting a decelerating state in which the wheel loader decelerates;
- detecting that the wheel loader is performing excavation work when a first predetermined period of time or more has elapsed since an operation of a forward/reverse changeover switch that is operated to switch a traveling direction of the wheel loader from forward to reverse or vice versa, a speed ratio at the torque converter calculated by dividing an output rotational speed by an input rotational speed decreases to a predetermined value or less, the deceleration state of the wheel loader continues over a second predetermined period of time, and the vehicle speed detector detects that the speed of the wheel loader is equal to or less than a predetermined speed;
- and
- downshifting a speed stage at the shift mechanism to speed 1 as the wheel loader is detected to be performing the excavation work.
Dependencies are inferred from the claim text.