Hydrostatic Travel Drive Reversal With Automatic Brake Assistance
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Solution Overview
Problem
The high mechanical stress on the components of a hydrostatic drive train in work vehicles during changes in direction, particularly when loaded, due to the reliance on hydrostatic drivetrain deceleration without active brake assistance from the driver.
Innovation Solution
Implementing an electronically controlled braking system that automatically supports deceleration by actuating the brakes of the braking system when changing direction, using sensors to detect vehicle speed and operating parameters to determine brake pressure, and releasing brakes before the vehicle stops to prevent subsequent acceleration issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the driver keeps their foot on the accelerator pedal during direction change, then the deceleration is achieved solely via the hydrostatic drivetrain, but this causes detrimentally high mechanical stress on the hydrostatic drive train components
Solution Approach 1:
The electronically controlled braking system acts as an intermediary between the driver's accelerator pedal input and the hydrostatic drivetrain. When the control element is switched to initiate a direction change, the brake control unit automatically activates the brake circuit to provide deceleration support, thereby mediating the load transfer away from the hydrostatic components while maintaining the driver's simple foot-on-accelerator operation.
Solution Approach 2:
The patent replaces reliance on purely mechanical/hydrostatic deceleration with an electronically controlled braking system. The brake control unit electronically detects the direction change intent and automatically activates the brake circuit, substituting the need for driver brake pedal intervention and reducing mechanical stress on the hydrostatic drive train during the deceleration phase of direction changes.
2Strength
If automatic brake actuation is implemented during direction change, then mechanical stress on hydrostatic drivetrain is reduced, but the system complexity increases due to electronic brake control integration
Solution Approach 1:
The electronic brake control unit is designed to serve multiple functions: it controls the brake circuit for automatic deceleration support during direction changes, monitors vehicle operating parameters, and integrates with the existing hydrostatic drive control system. This multi-functionality justifies the added complexity by providing comprehensive vehicle control capabilities beyond单一的 brake actuation.
Solution Approach 2:
The brake control unit operates autonomously by automatically detecting when a direction change is initiated through control element switching and self-activating the brake circuit without requiring driver intervention. The system monitors its own operating conditions and automatically manages the braking process, reducing the need for additional complex control mechanisms.
3Adaptability or versatility
If the hydrostatic pump delivery volume is continuously reduced to zero and then increased again during direction change, then the direction reversal is achieved, but the mechanical load on hydrostatic drive train components increases significantly
Solution Approach 1:
The brake control unit activates the brake circuit in advance during the direction change process, before the hydrostatic pump delivery volume reaches zero. This preliminary braking action reduces the vehicle's momentum and speed while the hydrostatic system is still providing drive force, thereby reducing the mechanical load on hydrostatic components during the critical reversal phase when the pump must rapidly change from forward to reverse flow.
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
Reduces mechanical stress on the hydrostatic drivetrain components, extending their service life and ensuring smooth direction changes without driver intervention on the brake pedal.
Implementation Method 1
the delivery volume of the hydrostatic pump is first continuously reduced to zero and then increased again with the reverse flow direction
Implementation Method 2
the deceleration of the work vehicle is supported by automatic actuation of the brakes of the electronically controlled brake circuit
Data Source
Figure 1~3
Figure 2a~2b
Figure 4
AI summary
The invention relates a method for controlling a change in the direction of travel of a working vehicle (2) between forward travel and rearward travel or vice versa, wherein the working vehicle (2) has an electronically controllable hydrostatic travel drive (3), has a power-operated brake system (22) with at least one electronically controllable brake circuit (106) and has an electronic brake-control unit (40) for controlling the travel drive (3) and also the at least one electronically controllable brake circuit (106) of the brake system (22), and in which method, while the vehicle is travelling in a first direction of travel (15), a change in the direction of travel to the opposite direction of travel (17) is initiated by a switchover (69) of the hydrostatic travel drive (3) by means of an assigned manual operating element (70). To reduce the mechanical loading of the components of the hydrostatic drive train (3.1) of the travel drive (3), it is provided that, when the mentioned change in the direction of travel is being carried out, the deceleration of the working vehicle (2) is assisted by an automatic actuation of the brakes (113a, 113b) of the electronically controllable brake circuit (106) of the brake system (22), wherein these brakes (113a, 113b) are actuated by being triggered by the switchover (69) of the operating element (70) and are released again at the latest when the vehicle comes to a standstill (vF = 0).