Gerotor Motor Parking Lock Piston Mechanism
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Solution Overview
Problem
Existing parking lock mechanisms for low-speed, high-torque gerotor motors are either unpredictable in performance due to variations in clearances or require significant redesign and larger components to handle full output torque, posing challenges in compact hydraulic applications.
Innovation Solution
A rotary fluid pressure device with a housing member, valve member, and moveable release and lock piston members, where a drive shaft with a pin member connects the release and lock pistons, allowing for axial movement and engagement with the gerotor displacement mechanism to provide a compact and reliable parking lock function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a brake or lock device is incorporated into the gerotor motor, then parking lock function is provided, but the device size increases and requires substantial redesign of housing and components
Solution Approach 1:
The patent combines the parking lock function with the existing gerotor motor structure by integrating a lock piston that engages with the gerotor star directly within the motor housing. This merging approach eliminates the need for separate brake packages on the output shaft, providing parking lock functionality without substantially increasing device size or requiring major redesign of housing and components.
2Force
If a multi-disc brake assembly is used to handle full output torque, then sufficient braking capacity is achieved, but the discs, spring, and piston must be relatively larger
Solution Approach 1:
The patent extracts the essential locking function from a complex multi-disc brake assembly and implements it through a simplified lock piston mechanism that engages directly with the gerotor star teeth. This extraction approach provides sufficient braking capacity to handle full output torque while using smaller, more compact components compared to traditional multi-disc brake assemblies.
3Volume of moving object
If a lock piston is disposed adjacent to the gerotor gear set, then compact design is achieved, but size restrictions in current hydraulic applications still pose challenges
Solution Approach 1:
The patent designs the lock piston mechanism to be universally applicable across various hydraulic applications by integrating it into the standard gerotor motor housing structure. The lock piston can engage with the gerotor star in a manner that is compatible with existing hydraulic systems, including mini-excavators, while maintaining a compact footprint that meets size restrictions in current applications.
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 enables a compact and reliable parking lock mechanism that effectively engages and disengages without requiring substantial redesign or larger components, addressing the issues of unpredictability and size constraints in low-speed, high-torque gerotor motors.
Implementation Method 1
A lock piston member, which is moveable between a first and second position, is disposed in the piston cavity
Implementation Method 2
When hydraulic pressure is supplied to the device, this hydraulic pressure acts against the lock piston to disengage the piston from the gerotor gear set
Implementation Method 3
A spring biases the lock piston into engagement with the gerotor gear set when hydraulic pressure is not supplied to the device
Data Source
Figure 1
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Figure 3
AI summary
A rotary fluid pressure device (11) includes an end cap (23) which is disposed rearwardly of, and adjacent, the fluid displacement mechanism (21 ). The end cap defines a piston cavity (103) in which is disposed a lock piston (105), which is moveable between a first position and a second position, in which the forward portion (107) of the lock piston extends within a central opening (121) of a rotor member (49) to prevent movement. A release piston (137) is disposed in a central opening (125) of one of the housing member (13) and stationary valve member (63). A brake pin (141) is disposed in a bore (139) of a drive shaft (57), with a first axial end of the brake pin being operably associated with release piston and a second axial end being operably associated with the lock piston.