Hydrostatic Transmission Isolation for Slope Stability
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Solution Overview
Problem
Existing hydraulic apparatuses, such as Twin-Lock systems, face challenges in maintaining stability and preventing self-sustained oscillations on steep uphill slopes, especially when one wheel starts to slip, due to uneven weight distribution and torque shifts, which current solutions fail to fully address.
Innovation Solution
A hydrostatic transmission apparatus with a hydraulic pump and two motors, featuring isolation means that allow separate communication of elementary motors with the pump's main ports, enabling a 'work' mode with higher cylinder capacity and a 'road' mode with reduced capacity, and incorporating a bypass duct with a pressure reducer and check valve to manage pressure and prevent wheel spin during braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Twin-lock apparatus is used to synchronize front and rear drive members, then wheel spin is avoided under most circumstances, but self-sustained oscillations occur on steep uphill slopes when weight distribution becomes uneven
Solution Approach 1:
The patent applies local quality by making the connection between elementary motors and the pump selective rather than uniform. Isolation means (valves or disconnect means) are introduced to allow different connection configurations for different operating conditions. In normal operation, all elementary motors connect to the pump for synchronized drive. On steep slopes, the isolation means selectively disconnect elementary motors that would generate destabilizing torque, allowing only those contributing to stable propulsion to remain connected.
Solution Approach 2:
The patent implements dynamics by making the hydraulic circuit configuration changeable based on operating conditions. The system transitions from a fixed Twin-lock configuration to a dynamic configuration where isolation means can selectively connect or disconnect elementary motors from the pump. This allows the system to adapt its torque distribution in real-time, maintaining stability on steep slopes by dynamically reconfiguring which motors receive hydraulic fluid and generate torque.
2Speed
If elementary motors are connected in parallel to pump ports to enable road mode with reduced cylinder capacity, then speed increases, but pressure differences cause harmful effects on the motors
Solution Approach 1:
The patent introduces isolation means as intermediary components between the elementary motors and the pump ports. These isolation means (valves or disconnect means) act as mediators that control the connection state, ensuring that when elementary motors are connected in parallel for road mode operation, the pressure differences do not cause harmful effects. The intermediary components regulate fluid flow and pressure distribution to protect the motors while enabling high-speed operation.
3Stability of the object's composition
If isolation means are introduced to prevent oscillations, then vehicle stability improves, but device complexity increases
Solution Approach 1:
The patent applies the taking out principle by extracting or removing certain elementary motors from the active hydraulic circuit when needed, rather than having all motors continuously connected. The isolation means enable selective disconnection of specific elementary motors from the pump, taking them out of the torque-generating configuration when their operation would cause instability on steep slopes. This reduces the active system complexity while maintaining the capability for stable operation.
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
This configuration enhances drivability and stability by isolating elementary motors, reducing the risk of self-sustained oscillations and improving braking capacity, while maintaining efficient speed differences between modes and preventing wheel reversal during slippery conditions.
Implementation Method 1
a hydraulic pump with two main ports; a first hydraulic motor; a second hydraulic motor including at least a first elementary motor and a second elementary motor, each elementary motor and the first motor having first and second enclosures for feeding fluid to the motor and for discharging fluid therefrom
Implementation Method 2
incorporating a bypass duct with a pressure reducer and check valve to manage pressure and prevent wheel spin during braking
Implementation Method 3
incorporating a bypass duct with a pressure reducer and check valve to manage pressure and prevent wheel spin during braking
Data Source
AI summary
The present disclosure is directed to a hydrostatic transmission apparatus including a pump, a first motor, and a second motor having two elementary motors. Each of the motors having first and second enclosures for feed/discharge. In work mode and in road mode, the second enclosure of the first elementary motor of the second motor and the first enclosure of the first motor are connected together in series, the second enclosure of the first motor being connected to the second port of the pump, and the second enclosure of the second elementary motor of the second motor is connected to the second port of the pump. In work mode, the first enclosure of each of the two elementary motors of the third motor is connected to the first port of the pump.