US 12,441,283 B2 · Dump truck

Abstract

A dump truck reduces drive wheel braking torques to avoid locking drive wheels during slipping and generates braking torques for driven wheels to ensure an overall braking torque using a controller that outputs a regenerative torque command value, corresponding to a brake pedal operation amount, to an inverter that regeneratively controls electric motors. The controller reduces the regenerative torque command value and outputs a drive command value, corresponding to a regenerative torque command value reduction amount, to a solenoid proportional valve, when the controller determines that slip ratios of rear wheels equal or exceed a predetermined value. A hydraulic pressure generated by a hydraulic valve based on the brake pedal operation amount actuates rear wheel brakes. A hydraulic pressure selected by a higher-pressure selecting valve that selects the higher of the hydraulic pressure from the hydraulic valve and the hydraulic pressure from the solenoid proportional valve actuates front wheel brakes.

A dump truck comprising:

a plurality of drive wheels;
a plurality of driven wheels;
an electric motor for driving the plurality of drive wheels;
an inverter for controlling the electric motor;
a first brake pedal operable by a driver;
a controller configured to output a regenerative torque command value for generating a braking torque corresponding to an operation amount of the first brake pedal to the inverter and to cause the inverter to regeneratively control the electric motor;
a second brake pedal operable by the driver;
a hydraulic valve for generating a hydraulic pressure corresponding to an operation amount of the second brake pedal;
a plurality of drive wheel brakes combined with the plurality of respective drive wheels and actuated according to the hydraulic pressure generated by the hydraulic valve;
and
a plurality of driven wheel brakes combined with the plurality of respective driven wheels and actuated according to the hydraulic pressure generated by the hydraulic valve,
wherein the dump truck further includes
a plurality of drive wheel peripheral velocity sensors that sense respective peripheral velocities of the plurality of drive wheels,
a plurality of driven wheel peripheral velocity sensors that sense respective peripheral velocities of the plurality of driven wheels,
a solenoid proportional valve for generating a hydraulic pressure, and
a higher-pressure selecting valve for selecting and delivering a higher one of the hydraulic pressure from the hydraulic valve and the hydraulic pressure from the solenoid proportional valve,
the controller is configured to, when the first brake pedal is operated and the second brake pedal is not operated, compute a theoretical value of a vehicle velocity when a braking torque corresponding to the operation amount of the first brake pedal is generated, set a larger one of a maximum velocity among the peripheral velocities sensed by the plurality of drive wheel peripheral velocity sensors and the plurality of driven wheel peripheral velocity sensors and the theoretical value of the vehicle velocity as a predicted value of the vehicle velocity, compute slip ratios of the plurality of the drive wheels from the peripheral velocities of the plurality of drive wheels sensed by the plurality of drive wheel peripheral velocity sensors and the predicted value of the vehicle velocity, and determine whether or not the slip ratios of the plurality of drive wheels are equal to or larger than a predetermined value,
the controller is configured to reduce the regenerative torque command value and output a drive command value for generating a braking torque corresponding to the reduction amount of the regenerative torque command value to the solenoid proportional valve, when determining that a slip ratio of at least one of the drive wheels is equal to or larger than the predetermined value,
the solenoid proportional valve generates a hydraulic pressure corresponding to the drive command value, and
the plurality of driven wheel brakes are actuated according to the hydraulic pressure selected by the higher-pressure selecting valve.

17 more elements

Dump truck

Life of this patent

Dump truck

Life of this patent

Abstract

Claims12