Hydrostatic-Mechanical Transmission Braking Control
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Solution Overview
Problem
Existing vehicle systems face challenges in decelerating without impairing the drive machine, particularly when decelerating from higher speeds, as the braking effect is inadequate and can lead to overspeed, resulting in potential damage to the engine.
Innovation Solution
A vehicle with a hydrostatic-mechanical power-split transmission device and a braking system that includes an additional actuating device connected to the power demand and direction selection elements, allowing for automatic activation of the braking device via a proportional valve to introduce braking torque when the drive motor reaches impermissible speeds, thereby protecting the drive machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the drive machine is transferred to overrun mode during deceleration to provide braking effect, then fuel consumption is reduced, but the drive machine may reach impermissible speeds that impair its functioning
Solution Approach 1:
The control device continuously monitors the rotational speed of the drive machine and automatically adjusts the transmission ratio when a threshold is exceeded, creating a feedback loop that prevents overspeed while maintaining energy-efficient overrun operation
Solution Approach 2:
The transmission ratio is dynamically adjusted during deceleration based on real-time drive machine speed conditions, allowing the system to transition from standard deceleration to enhanced braking mode when needed
2Force
If the transmission ratio is increased during deceleration to enhance engine braking effect, then braking capability is improved, but the complexity of the transmission control increases
Solution Approach 1:
The system uses the drive machine's own rotational speed as the trigger for automatic transmission ratio adjustment, eliminating the need for external sensors or complex control systems while maintaining effective braking
3Power
If the drive machine is decoupled from the main transmission during direction change, then engine power is available for hydraulic functions, but energy required to brake the vehicle cannot be recuperated
Solution Approach 1:
The main transmission is designed to perform multiple functions simultaneously - directing power to hydraulic pumps during direction changes while also enabling energy recuperation during deceleration through controlled engagement
Data Source
Figure 1
AI summary
A vehicle 1 is described, having a drive train (2) which comprises a gear mechanism device (4) which is operatively connected thereto and has hydrostatic/mechanical power splitting, and a drive (5), and having at least one brake device (8). The brake device (8) is assigned an additional activation device (29) which is operatively connected to a power requesting element (15) and/or an element for selecting the direction of travel and by means of which activation device (29) the brake device (8) can be activated when a deceleration (1) which is requested by means of the power requesting element (15) and/or the element (19) for selecting the direction of travel occurs and in the present case in the force flux between the drive machine (2) and the output (5) to a scope which applies a braking of the torque to the drive train. When a requested deceleration vehicle (1) is present, a drive-machine-side thrust torque is made available in the region of the output (5) when the brake device (8) is not activated on the driver's side. If a rotational speed of the drive machine (2) exceeds a defined rotational speed threshold, the brake device (8) is activated to a scope which applies a brake torque to the drive train (2).