Pressure Balancing System for Tandem Master Cylinders
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Solution Overview
Problem
Tandem master cylinders with stroke-controlled pressure balancing systems have an excessive axial size due to the need for sealing gaskets that must slide to enable communication between balancing ducts and sections, which increases the length of the pistons and master cylinders, posing a challenge in compact design for farm vehicles.
Innovation Solution
A pressure balancing system featuring a primary balancing system with a primary balancing duct and O-ring forming a valve that opens during plunger stroke, and a secondary balancing system with a secondary balancing duct and O-ring forming a valve that opens as the plunger travels, allowing for fluid communication between chambers without the need for extensive piston and cylinder length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stroke-controlled pressure balancing is implemented using sliding sealing gaskets in pistons, then pressure balancing reliability is improved, but the axial size of the master cylinder increases excessively
Solution Approach 1:
The patent replaces the mechanical sliding gasket system with a valve mechanism controlled by piston position. Instead of using sealing gaskets that must slide along the piston to maintain continuous sealing while enabling balancing duct communication, the invention uses valves (21, 22) that are actuated by the piston position to open or close balancing passages. This substitution eliminates the need for long sliding gaskets, thereby reducing the axial size of the master cylinder while maintaining reliable pressure balancing control.
Solution Approach 2:
The patent introduces valves as intermediary elements between the piston and the balancing ducts. These valves act as mediators that control fluid flow based on piston position without requiring the piston itself to maintain complex sealing arrangements over long distances. The valves enable the balancing function to be activated at specific piston positions while allowing the use of shorter, more compact piston and cylinder designs.
2Adaptability or versatility
If sliding sealing gaskets are used to enable balancing duct communication throughout the piston stroke, then pressure balancing function is achieved, but the piston and master cylinder lengths must be increased
Solution Approach 1:
The patent implements dynamic control of the balancing function through position-dependent valve actuation. Instead of requiring continuous communication between balancing ducts throughout the entire piston stroke (which would necessitate long sliding gaskets), the system dynamically opens balancing passages only when the piston reaches specific positions. This dynamic approach allows the master cylinder to be more compact while still providing the necessary pressure balancing function during the braking operation.
Solution Approach 2:
The patent uses preliminary action by positioning the valves and balancing ducts such that the balancing function is activated at predetermined piston positions. The valves are arranged to open automatically when the piston reaches specific points in its stroke, eliminating the need for continuous mechanical sealing arrangements. This preliminary positioning of balancing elements allows for shorter master cylinder design while ensuring the balancing function is available when needed.
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 design reduces the axial size of tandem master cylinders while maintaining effective pressure balancing, ensuring reliable operation even in case of malfunctions by independent primary and secondary fluid supply circuits and control pressures.
Implementation Method 1
a primary balancing O-ring arranged to cooperate in fluid-tight manner with a surface of the secondary plunger so as to form a primary balancing valve
Data Source
Figure 1
AI summary
A pressure balancing system for a pair of tandem master cylinders (10), where each of said tandem master cylinders comprises a primary plunger (101), a secondary plunger (102), a primary chamber (125), a secondary chamber (126) and a secondary preload sub-assembly, comprising a secondary preload pin (114) and a secondary preload case (111). The pressure balancing system comprises a primary balancing system and a secondary balancing system. The primary balancing system includes a primary balancing duct (115) establishing communication of a primary balancing channel with the master cylinder (10) at a region occupied by the secondary plunger (102) when the latter is in an initial rest position. The primary balancing system further includes a primary balancing O-ring (116a) forming a primary balancing valve between the primary balancing duct (115) and the primary chamber (125). The secondary balancing system comprises a secondary balancing duct (136) formed within the secondary preload pin (114) and having a second end ending with at least one radial hole (137), and a secondary balancing O-ring (112), which is fixed to the secondary preload case (111).