Hydrostatic Transmission Pressure Control Valve
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Solution Overview
Problem
Existing hydrostatic transmission devices for mobile machines face challenges in managing pressure distribution between front and rear wheels, leading to potential damage and wheel slippage, especially on steep slopes, due to complex hydraulic circuit architectures and inadequate pressure control.
Innovation Solution
A hydrostatic transmission device with a pressure control valve connected to a selector that selectively connects to either the 'reverse' or 'forward' high-pressure line based on pressure differences, simplifying the circuit architecture and eliminating the need for feedback devices by allowing series pipes to discharge or recharge through high-pressure lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure control valve connected to the low pressure circuit is used to limit maximum pressure in series pipes, then torque transferred to wheels is limited to mechanically acceptable values, but the hydraulic circuit architecture becomes complex requiring make-up valves and electrical management
Solution Approach 1:
The invention extracts the pressure control function from the low pressure circuit and relocates it to the high pressure circuit. The pressure control valve is now connected to the high pressure supply line directly, allowing it to regulate pressure at the source before fluid enters the series pipes connecting front and rear axles. This eliminates the need for complex make-up valves and electrical management systems while maintaining reliable pressure control.
Solution Approach 2:
The high pressure circuit acts as an intermediary between the pump and the series pipes. By connecting the pressure control valve to the high pressure supply line, the system uses this intermediate high pressure circuit to distribute controlled pressure to both front and rear axles simultaneously, simplifying the overall hydraulic architecture while maintaining effective torque distribution control.
2Object-affected harmful factors
If a flow control valve linked to steering angle is used to evacuate excess flow during cornering, then pressure rises during turning are reduced, but sudden pressure rises on steep slopes are not eliminated and the valve is set for estimated speed only
Solution Approach 1:
The invention replaces the static flow control valve with a dynamic pressure control system. The pressure control valve connected to the high pressure circuit responds dynamically to actual pressure conditions in real-time, automatically adjusting flow distribution based on whether the machine is cornering, climbing, or descending. This dynamic response eliminates sudden pressure rises across all driving conditions without being limited to estimated speeds.
Solution Approach 2:
The pressure control valve incorporates feedback from the high pressure circuit to automatically regulate pressure distribution. By monitoring actual pressure conditions in the high pressure supply line and adjusting flow distribution accordingly, the system adapts to different driving conditions including cornering and steep slopes without requiring manual adjustment or being limited to predetermined speeds.
3Strength
If a pressure limiter set to maximum admissible value is used, then maximum pressure in the circuit is protected, but pressure remains high in series pipes causing sudden pressure variations and front wheel slippage on steep climbs
Solution Approach 1:
The invention applies local quality control by connecting the pressure control valve directly to the high pressure supply line, allowing different pressure levels to be maintained in different parts of the circuit. The valve can limit maximum pressure at the source while allowing lower, more stable pressure distribution to the series pipes connecting front and rear axles. This localized control prevents front wheel slippage on steep climbs while maintaining overall circuit protection.
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 solution effectively manages pressure distribution, reducing the risk of damage and slippage by simplifying the hydraulic circuit, allowing for efficient torque management and improved wheel grip across varying driving conditions.
Implementation Method 1
The selector is controlled according to the pressure difference between the 'forward' high pressure pipe and the 'reverse' high pressure pipe
Data Source
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AI summary
The device has a hydraulic pump (P) whose main orifices are connected to a high pressure reversing pipe (1) and a high pressure forwarding pipe (2). Pressure control valves (Vd, Vg) are connected to left and right series pipes (3d, 3g). The control valves are connected to respective selectors (Se) that are controlled based on pressure difference between the reversing and forwarding pipes for selectively connecting series pipes to the reversing pipe or to the forwarding pipe. A torque limiter is arranged between each control valve and each selector. An independent claim is also included for a method for controlling hydrostatic pressure in a vehicle.