Hybrid working vehicle
A hybrid working vehicle comprises an engine, a drive wheel, a power take-off (PTO) shaft, and a power transmission system for transmitting power from the engine to the drive wheel and the PTO shaft. The power transmission system is bifurcated at a bifurcating point into a traveling drive train for driving the drive wheel and a PTO drive train for driving the PTO shaft. A continuously variable transmission is provided on the traveling drive train, and a motor generator is provided on the power transmission system between the engine and the bifurcating point. The motor generator functions as a generator by power of the engine and functions as an electric motor for driving the power transmission system. The hybrid working vehicle includes a controller for controlling an output rotary speed of the motor generator functioning as the electric motor.
1. A hybrid working vehicle, comprising:
an engine;
a drive wheel;
a power take-off (PTO) shaft;
a power transmission system for transmitting power from the engine to the drive wheel and the PTO shaft, the power transmission system being bifurcated at a bifurcating point into a traveling drive train for driving the drive wheel and a PTO drive train for driving the PTO shaft;
a continuously variable transmission provided on the traveling drive train;
a motor generator provided on the power transmission system between the engine and the bifurcating point,
wherein the motor generator functions as a generator driven by the engine to charge electric power in a battery or functions as an electric motor supplied with electric power from the battery to drive the power transmission system; and
a controller for controlling an output rotary speed of the motor generator functioning as the electric motor,
wherein the engine and the motor generator are assembled as a power unit having an output therefrom to the bifurcating point, and
wherein the output of the power unit is one selected among an output power of only the engine, an output power of only the motor generator functioning as the electric motor, and a combined output power of the engine and the motor generator functioning as the electric motor.
2. The hybrid working vehicle according to claim 1 , further comprising:
a second transmission provided on the traveling drive train,
wherein the second transmission includes a transmission clutch interposed between an upstream side drive member drivingly connected to the engine and a downstream side drive member drivingly connected to the drive wheel; and
a first electric motor drivingly connected to the downstream side drive member and driven by the electric power supply from the battery,
wherein, when the transmission clutch of the second transmission is engaged to drivingly connect the upstream side drive member to the downstream side drive member, the controller controls an output rotary speed of the first electric motor so as to drive the downstream side drive member synchronously to the upstream side drive member.
3. The hybrid working vehicle according to claim 1 , wherein the drive wheel driven by the traveling drive train is defined as a main drive wheel, wherein the hybrid working vehicle further comprises:
an auxiliary drive wheel; and
a second electric motor drivingly connected to the auxiliary drive wheel and driven by the electric power supply from the battery,
wherein the controller controls the driving on-and-off of the second electric motor so as to select either a four-wheel drive mode to drive the main and auxiliary drive wheels or a two-wheel drive mode to drive only the main drive wheel.
4. The hybrid working vehicle according to claim 3 , further comprising:
a differential speed detection means for detecting a differential peripheral speed between the main drive wheel and the auxiliary drive wheel,
wherein during travel of the hybrid working vehicle in the two-wheel drive mode, when the differential peripheral speed detected by the differential speed detection means exceeds a threshold, the controller supplies electric power from the battery to the second electric motor for driving the auxiliary drive wheel so as to change the four-wheel drive mode to the two-wheel drive mode.
5. The hybrid working vehicle according to claim 3 , further comprising:
an auxiliary clutch interposed between the second electric motor and the auxiliary drive wheel,
wherein the auxiliary clutch is disengaged when the electric power supply to the second electric motor is stopped.
6. The hybrid working vehicle according to claim 5 , wherein the auxiliary clutch is a one-way clutch.
7. The hybrid working vehicle according to claim 5 , wherein the auxiliary clutch is a bi-directional clutch that can be operated regardless of whether the auxiliary drive wheel rotates in the forward traveling direction or the backward traveling direction.
8. The hybrid working vehicle according to claim 3 ,
wherein the auxiliary drive wheel is steerable,
wherein the hybrid working vehicle further comprises:
a turn angle detection means for detecting a turn angle of the auxiliary drive wheel, and
wherein, when the turn angle of the auxiliary drive wheel detected by the turn angle detection means exceeds a threshold, the controller commands the second electric motor to increase the output rotary speed so as to make a peripheral speed of the auxiliary drive wheel exceed a peripheral speed of the main drive wheel.