Radial Planetary Gear in Annular Hydrostatic Actuator
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Solution Overview
Problem
Hydrostatic actuators used in motor vehicles face challenges in increasing efficiency, reducing installation space, and enhancing operating pressure, particularly in converting rotary drives to axial movements efficiently.
Innovation Solution
A hydrostatic actuator design featuring a planetary rolling gear arranged radially within an annular pressure chamber, with an electric motor and gear spindle arranged coaxially, allowing for a compact structure and reduced installation space, and incorporating a one-piece housing and integrated pressure medium reservoir to optimize space usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the planetary rolling gear is arranged in the rotor of the electric motor, then the structure is compact, but the installation space requirement increases
Solution Approach 1:
The planetary rolling gear is nested within the annular pressure chamber, with the gear spindle positioned coaxially. This nested arrangement allows the planetary rolling gear components to be contained within the existing motor housing space, converting rotary motion to axial motion without increasing the overall footprint of the actuator assembly.
Solution Approach 2:
The planetary rolling gear converts rotary motion in the radial dimension to axial motion along the longitudinal axis. By arranging the gear spindle and planetary rolling bodies to translate rotational movement into axial displacement of the piston, the system achieves compact radial dimensions while maintaining effective actuation space.
2Length of moving object
If the sleeve of the planetary rolling gear is arranged radially within the pressure chamber, then the diameter is reduced, but the installation space available for the rotor becomes limited
Solution Approach 1:
The pressure chamber is designed with an annular cross-section, creating a ring-shaped working volume around the planetary rolling gear. This annular configuration optimizes the local space distribution, allowing the rotor to be positioned coaxially with sufficient radial clearance for magnetic components while maintaining a compact overall diameter determined by the outer radius of the annular chamber.
Solution Approach 2:
The planetary rolling gear and gear spindle are pre-positioned in a fixed radial arrangement within the pressure chamber during manufacturing. This preliminary positioning establishes the radial clearance requirements, allowing the rotor dimensions to be optimized based on the predetermined gear configuration rather than requiring additional radial space.
3Adaptability or versatility
If the electric motor diameter is increased to accommodate the planetary gear, then the planetary gear can be properly installed, but the overall actuator diameter increases
Solution Approach 1:
The housing of the electric motor and the housing of the master cylinder are merged into a single integrated structure. This combined housing design allows the planetary rolling gear to be installed within the shared space of the unified housing, eliminating the need for separate motor and cylinder housings and reducing the overall actuator diameter compared to designs with separate components.
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 enables a more efficient and compact hydrostatic actuator with improved axial displacement capabilities and reduced installation space requirements, suitable for various applications in motor vehicles, including transmission and brake systems.
Implementation Method 1
planetary rolling bodies rolling between them
Implementation Method 2
piston which is axially displaceable in the housing and pressurizes a pressure chamber filled with pressure medium
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to a hydrostatic actuator, comprising a master cylinder containing a housing and a piston, which is axially mountable in the housing and which pressurizes a pressure chamber filled with pressure medium, a planetary rolling-contact gear system that converts a rotary drive into an axial motion and that has a sleeve, a gear-driven spindle, and planetary rolling elements that roll therebetween, and an electric motor that drives the planetary rolling-contact gear system and that has a stator rigidly connected to a housing and a rotor that can be rotated relative to the stator. In order to optimize the installation space, the pressure chamber is annular and the planetary rolling-contact gear system is arranged radially within the pressure chamber.