Valve Assembly Segmentation for Low Cracking Pressure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional modulators in vehicle braking systems face challenges when reduced in size, as the cracking pressure increases, leading to unacceptable delays in brake actuation due to higher energization and frictional forces proportional to the main piston diameter, rather than its square.
Innovation Solution
A modified valve assembly with a first valve member extending through an aperture in a second movable element, allowing the second movable element to increase control chamber volume and push the first movable element away from the inlet, reducing the effect of reservoir pressure on energization forces, and featuring a reservoir seat design that minimizes the diameter of the reservoir seat to reduce spring force requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the modulator size is reduced, then the device compactness is improved, but the cracking pressure increases leading to delayed brake actuation
Solution Approach 1:
The patent divides the single piston system into two separate movable elements: a control piston (second movable element) and a main piston (first movable element). The control piston controls fluid admission to the main chamber, while the main piston directly controls the reservoir seat. This segmentation allows the reservoir seat diameter to be minimized independently of the control piston diameter, reducing energization forces and cracking pressure in the compact design.
Solution Approach 2:
The control piston acts as an intermediary between the control chamber and the main piston. It controls the admission of control fluid to the main chamber, thereby indirectly controlling the position of the main piston and the reservoir seat. This intermediary mechanism allows precise control of the reservoir seat position with minimal spring force requirements, enabling compact modulator design with low cracking pressure.
2Force
If the reservoir seat diameter is minimized, then the spring force requirements are reduced, but the sealing effectiveness may be compromised
Solution Approach 1:
The patent employs dynamic control of the reservoir seat position through the main piston, which is actuated by control fluid pressure in the main chamber. The seat remains dynamic rather than statically pressed by spring force alone. This dynamic positioning allows the minimal-diameter seat to maintain reliable sealing through controlled pressure forces while minimizing spring force requirements.
Solution Approach 2:
The patent uses control fluid pressure in the main chamber to actuate the main piston, which in turn controls the reservoir seat position. This pneumatic/hydraulic actuation mechanism provides reliable sealing force through fluid pressure rather than relying solely on spring force, enabling the use of a minimal-diameter seat while maintaining sealing effectiveness.
3Quantity of substance
If the control piston diameter is reduced, then the control chamber volume can be minimized, but the energization forces increase proportionally to diameter rather than square
Solution Approach 1:
The patent segments the force control function between the control piston and main piston. The control piston (with smaller diameter) controls fluid admission to the main chamber, while the main piston (with larger area) generates the actual energization force on the reservoir seat. This segmentation allows the control chamber to be compact while the main piston provides sufficient energization force through its larger surface area exposed to control fluid pressure.
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 solution maintains an acceptable cracking pressure of around 0.2 bar even with a reduced control piston diameter of 50mm, addressing the issue of increased cracking pressure in smaller modulators and ensuring timely brake actuation.
Implementation Method 1
movable relative to the housing under the influence of fluid pressure in the control chamber and main chamber
Implementation Method 2
a spring provided between the first movable element and an end face of the housing, the spring biasing the first movable element towards the second movable element
Implementation Method 3
engagement of the first valve member and first movable element substantially preventing flow of fluid between the inlet port and the delivery port
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A valve assembly including a housing (24') provided with an inlet port (12'), a delivery port (14'), and an exhaust port (16'), the valve assembly further including a first movable element (32'), a first valve member (34a') and a second valve member (26a'), the first movable element (32') being engageable with the first valve member (34a'), engagement of the first valve member (34a') and first movable element (32') substantially preventing flow of fluid between the inlet port (12') and the delivery port (14'), and the first movable element (32') also being engageable with the second valve member (26a'), engagement of the second valve member (26a') with the first movable element (32') substantially preventing flow of fluid between the delivery port (14') and the exhaust port (16'), the valve assembly further including a second movable element (26') which divides the housing (24') into a control chamber (22') and a main chamber (30') and which is movable relative to the housing (24') under the influence of fluid pressure in the control chamber (22') and main chamber (30'), wherein the first valve member (34a') extends from the housing (24') towards the first movable element (32') through an aperture provided in the second movable element (26').