Industrial Truck Holding Torque Control on Inclines
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Solution Overview
Problem
Industrial trucks face challenges in maintaining a stable position on inclined surfaces without overheating or overloading the travel drive or controller, especially when loaded, as existing solutions either consume excessive energy or lead to jerky movements during restart.
Innovation Solution
An industrial truck equipped with a holding brake and travel controller that adjusts a holding torque to keep the vehicle stationary on an incline, deactivates the travel drive when the brake is actuated, and reactivates the drive mechanism smoothly by applying the stored holding torque when restarting, with load and steering angle corrections to ensure stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active stopping via the travel drive is used to hold the vehicle on an incline, then the vehicle can be actively held at a standstill, but the travel drive overheats and the controller becomes overloaded
Solution Approach 1:
A holding brake is introduced as an intermediary device to take over the vehicle holding function from the travel drive. The holding brake acts as a mediator that provides the necessary holding torque on the wheels, allowing the travel drive to be deactivated and preventing overheating while maintaining reliable vehicle positioning on inclines
2Speed
If the holding brake is released immediately when the driving setpoint generator is actuated, then the vehicle can restart quickly, but jerky movements occur due to the sudden application of holding torque
Solution Approach 1:
The control device performs preliminary action by gradually reducing the holding brake's holding torque before complete release, rather than abrupt release. This preliminary reduction of holding torque prevents sudden jerky movements when the vehicle restarts, ensuring smooth transition while maintaining quick response to the driving setpoint generator activation
Solution Approach 2:
The holding torque of the brake is made dynamic rather than static. The control device continuously adjusts the holding torque based on the actuation state of the driving setpoint generator, transitioning from full holding torque to gradual reduction to zero torque, enabling both quick restart and smooth movement
3Reliability
If the travel drive remains active to maintain vehicle position, then the vehicle can be held stationary, but excessive energy is consumed and the drive is overloaded
Solution Approach 1:
The holding brake serves as an intermediary that assumes the vehicle position stability function, allowing the travel drive to be deactivated. This transfers the energy-intensive holding task from the electric travel drive to the mechanical holding brake, dramatically reducing energy consumption while maintaining position stability on inclines
Solution Approach 2:
The vehicle holding function is extracted from the travel drive system and assigned to a dedicated holding brake mechanism. This separation allows the travel drive to remain inactive during vehicle holding, eliminating unnecessary energy consumption and preventing drive overload while maintaining reliable position stability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively prevents overheating and jerky movements by using the holding brake to maintain the vehicle's position on inclines without active drive engagement, ensuring efficient energy use and stable restarts, even with changing loads and steering angles.
Implementation Method 1
a holding brake (32), wherein the driving controller (22) is designed to actuate the holding brake (32)
Data Source
Figure 1
Figure 2~3
AI summary
The truck (28) has a vehicle speed control unit for producing a desired value for driving speed, and adjusting a holding torque of a steerable traction drive when a drive controller is not actuated. The traction drive stationarily holds the truck at an inclined surface, and actuates a holding brake on and off. The drive controller controls the drive for generating a holding torque during operation of the vehicle speed control unit, and releases the holding brake. The drive controller stores control parameters and generates the holding torque based on the stored control parameters. An independent claim is also included for a method for adjusting a holding torque of an industrial truck.