Integrated Park Brake Layout for Compact Radial Piston Units
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Solution Overview
Problem
Radial piston units in hydrostatic systems have high axial and radial dimensions, and existing park brake mechanisms increase the axial length, making them unsuitable for compact designs in vehicles.
Innovation Solution
A brake mechanism is integrated within the casing of the radial piston unit, using a stationary and rotary casing with overlapping seals and brake discs, allowing for reduced dimensions while maintaining functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a park brake mechanism is arranged inside the casing of a hydrostatic radial piston unit, then the brake is protected from dirt and negative influences, but the axial length of the radial piston unit significantly increases
Solution Approach 1:
The brake mechanism is nested within the existing casing structure of the radial piston unit. The brake disc is positioned in the annular space between the cylinder block and the end cap, utilizing the existing internal volume of the casing rather than adding external components. This nesting approach protects the brake from external contaminants while avoiding significant increase in axial length.
Solution Approach 2:
Instead of arranging the brake mechanism in the axial direction (which would increase length), the patent positions the brake disc in the radial direction within the annular space of the existing casing. The brake mechanism utilizes the radial dimension and internal volume of the casing, transforming the spatial arrangement from axial extension to radial utilization, thereby protecting the brake while maintaining compact axial dimensions.
2Device complexity
If the dimensions of the radial piston unit are reduced, then the adaptation in the design of the frame is reduced, but the integration of a functional park brake mechanism becomes more difficult
Solution Approach 1:
The end cap of the radial piston unit casing serves multiple functions: it closes the hydraulic system, provides mounting surfaces for cylinders, and simultaneously serves as the stationary element for the brake mechanism. The brake disc is mounted on the output shaft while the brake caliper is mounted on the end cap, creating a compact integrated braking system that utilizes existing structural elements for dual purposes.
Solution Approach 2:
The brake mechanism is merged with the existing casing structure of the radial piston unit. The brake system shares the same housing and mounting points as the hydraulic motor, combining two functional systems (hydraulic drive and mechanical braking) into a single integrated assembly. This merging reduces overall device complexity while maintaining full brake functionality.
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 reduces the axial and radial dimensions of the radial piston unit, enabling compact integration into vehicle frames without increasing the brake mechanism's size, and simplifies assembly and reduces potential leakage points.
Implementation Method 1
the rotary casing and the stationary casing form together a closed fluid-tight cavity
Implementation Method 2
the brake mechanism comprises at least two brake discs arranged adjoined in the overlapping area, wherein one brake disc is rotationally fixed to the rotary casing and the other brake disc is rotationally fixed to the stationary casing
Data Source
AI summary
A hydrostatic radial piston unit of the cam-lobe type of construction including a non-rotary, stationary casing. The stationary casing includes a through hole defining a rotational axis of the hydrostatic radial piston unit. A rotary casing is mounted rotary to the non-rotary, stationary casing in an axial overlapping area. A park brake mechanism includes at least two brake discs arranged adjoined in the overlapping area. An end cover closes the non-rotary casing on a rear end side of the hydrostatic radial piston unit facing away from the rotary casing. The end cover pre-tensions a disc spring against a disc-shaped brake piston both located in the rear end portion of the stationary casing to generate an axially oriented spring force. The force can be forwarded by the brake piston to at least one brake pin arranged in an axially oriented bore in the stationary casing, in order to press the brake discs against each other when the brake piston on the face opposite to the disc spring is not forced to move towards the end cover.