Hydraulic Height Adjusting System with Sequential Valve Control
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Solution Overview
Problem
Existing hydraulic height adjusting systems for vehicles fail to ensure that the front axle is always lower than the rear axle during dynamic height adjustments, particularly at high speeds, which can lead to stability issues due to a 'take-off attitude', and are vulnerable to solenoid valve failures.
Innovation Solution
A hydraulic height adjusting system with a sequential control mechanism using two solenoid valves in series, where the rear axle actuators are extended or compressed before the front axle actuators, ensuring the front axle is always lower than the rear axle, and incorporating a pressure sensor to manage fluid flow and prevent overpressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If parallel solenoid valve control is used for height adjustment, then the system is simple and fast, but the vehicle may take off at high speed and stability is compromised
Solution Approach 1:
The system performs preliminary action by first extending the rear axle actuators before extending the front axle actuators during height adjustment. This sequential operation ensures that the rear axle is raised first, preventing the vehicle from taking off at high speed while maintaining adjustment speed. The preliminary extension of rear actuators creates a stable base before front actuators operate.
2Productivity
If parallel solenoid valve control is used, then the system responds quickly, but it cannot ensure front axle remains lower than rear axle during dynamic adjustment
Solution Approach 1:
The control system is segmented into two independent control paths: one for rear axle actuators and one for front axle actuators. Each path has its own solenoid valve (20, 26) that can be controlled sequentially. This segmentation allows the system to maintain high productivity through independent control while achieving precise positioning by ensuring rear actuators extend before front actuators, keeping the front axle lower than the rear axle during dynamic adjustment.
3Reliability
If one solenoid valve fails in a parallel system, then the system cannot maintain the required height relationship, but increasing redundancy reduces system simplicity
Solution Approach 1:
The system uses preliminary action in the control sequence where the rear axle solenoid valve (20) is activated first to extend rear actuators, and only after this preliminary action is complete does the front axle solenoid valve (26) activate. This sequential control ensures that even if one valve fails, the other can still operate in its designated sequence, maintaining the height relationship and improving reliability without significantly increasing complexity.
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 system maintains vehicle stability by ensuring the front axle is never higher than the rear axle during height adjustments, even in the event of solenoid valve failures, and prevents take-off attitudes, while also managing fluid pressure to avoid overpressures.
Implementation Method 1
a pump (P) which generates fluid under pressure to be supplied to the hydraulic actuators
Implementation Method 2
two flow-control solenoid valves (20, 26)... control the supply/discharge of the working fluid to/from the hydraulic actuators
Implementation Method 3
four hydraulic linear actuators (10, 12)... to change the distance between the axis of rotation of that wheel and the vehicle body
Implementation Method 4
incorporating a pressure sensor to manage fluid flow and prevent overpressures
Data Source
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AI summary
The system comprises: a first pair of hydraulic linear actuators (10) placed each between the vehicle body (B) and a respective rear wheel (RW) in such a manner that the extension and compression of each of these actuators (10) bring about an increase and a decrease, respectively, in the height of the vehicle body (B) from the ground at the rear axle; a second pair of hydraulic linear actuators (12) placed each between the vehicle body (B) and a respective front wheel (FW) in such a manner that the extension and compression of each of these actuators (12) bring about an increase and a decrease, respectively, in the height of the vehicle body (B) from the ground at the front axle; a supply unit (P) for generating a flow of fluid under pressure; a tank (T); a hydraulic circuit (14, 22, 24, 28, 30) connecting the first and the second pair of hydraulic linear actuators (10, 12) with the supply unit (P) and with the tank (T); and flow control means (20, 26, 34, 36, 38, 40, ECU) arranged to control the flow of the fluid under pressure from/to the first and the second pair of hydraulic linear actuators (10, 12) so as to ensure that, during raising or lowering of the vehicle body (B), the height of the vehicle body (B) from the ground at the front axle is always less than that at the rear axle.