Power Steering Torque Overlay via Summation Gear
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Solution Overview
Problem
Existing power steering assemblies for hydraulic power steering systems in vehicles face challenges in providing independent steering torque superimposition without the actuator following driver steering movements, leading to complexity and increased size and weight.
Innovation Solution
A power steering assembly incorporating a summation gear and epicyclic gear mechanism that allows independent superimposition of steering torque via an actuator, with a planetary gear system that transmits rotation between the input and output shafts without gearing, enabling a compact and lightweight design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional power steering assembly with two planetary gears is used to achieve steering torque superimposition, then independent steering torque control is enabled, but the device complexity, size, and weight increase
Solution Approach 1:
The patent extracts the essential function of torque superimposition from the complex two-planetary-gear system and implements it using a single planetary gear mechanism combined with an actuator. The actuator directly applies torque to the planetary gear's sun gear or ring gear, enabling independent torque control without requiring a second planetary gear set. This extraction of the core function reduces structural complexity while maintaining the adaptability for torque superimposition.
Solution Approach 2:
The patent merges the actuator with the planetary gear mechanism into an integrated unit. The actuator is positioned to directly interact with the planetary gear components (sun gear, ring gear, or planetary carriers), combining the torque application function with the gear mechanism in a single compact assembly. This merging eliminates the need for separate torque control mechanisms and reduces overall device complexity.
2Adaptability or versatility
If a conventional power steering assembly with two planetary gears is used to achieve steering torque superimposition, then independent steering torque control is enabled, but the weight increases
Solution Approach 1:
The patent removes one complete planetary gear set from the conventional two-gear configuration, retaining only the essential planetary gear mechanism needed for torque transmission. The actuator directly controls the retained planetary gear to achieve torque superimposition, significantly reducing the amount of metal components and overall assembly weight while preserving the adaptive torque control capability.
Solution Approach 2:
By merging the actuator with the single planetary gear mechanism, the patent creates a compact integrated unit that weighs less than the conventional separate two-gear system. The actuator's direct coupling with the planetary gear components eliminates intermediate transmission elements and reduces the total mass of moving parts.
3Reliability
If the actuator follows driver steering movements, then steering assistance is maintained, but independent steering torque superimposition cannot be achieved
Solution Approach 1:
The patent segments the torque control function into two independent pathways: (1) the driver's steering torque transmitted through the torsion bar to the planetary gear mechanism, maintaining steering assistance; and (2) the actuator's independent torque application to the planetary gear components for torque superimposition. This segmentation allows both functions to operate simultaneously without interference, as each pathway can be controlled independently through the shared planetary gear mechanism.
Solution Approach 2:
The planetary gear mechanism serves as an intermediary that receives torque from both the driver (via the torsion bar) and the actuator, and transmits the combined torque to the output shaft. This intermediary role allows the system to maintain steering assistance from the driver while simultaneously enabling independent torque superimposition from the actuator, resolving the contradiction between following driver movements and achieving independent control.
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
Enables independent steering torque superimposition without actuator movement synchronization, resulting in a simplified, smaller, and lighter power steering assembly with improved operational efficiency and reduced component complexity.
Implementation Method 1
a planetary gear which is in operative engagement with both the input shaft or output shaft and the actuator; the revolving wheel being rotatable both about a revolving axis of the revolving gear mechanism which is fixed to the frame and about its own axis of rotation which revolves around the revolving axis which is fixed to the frame
Data Source
Figure 1
AI summary
The invention relates to a power steering assembly for a hydraulic power steering of motor vehicles, comprising at least one hydraulic servo valve having a control member (3) for controlling the steering assistance depending on a relative rotation of an input shaft with respect to an output shaft (2), and at least one actuator (9) for relative adjustment of the control member (3) with respect to the input shaft or the output shaft (2) in order to influence the steering assistance characteristic. In addition, the power steering assembly comprises a summation gear having a first rotatable drive member (4) that is in functional engagement with the control member (3), and a second rotatable drive member (5) that is in functional engagement with an output element (8) of the actuator (9), as well as an output member (6). The summation gear overlays a rotation of the first drive member (4) with a rotation of the second drive member (5) and drives, via the output member (6), an epicyclic gearing comprising at least one planetary gear (11), which is in functional engagement together with both the input shaft or output shaft (2) and with the control member (3) and can be rotated both about a planetary axis (14) fixed with respect to the frame and also about a distinct axis of rotation (12) rotating about the planetary axis (14), in such a way that a rotation of the first drive member (4) causes a rotation of the axis of rotation (12) of the planetary gear (11) about the planetary axis (14) in such a way that no rotation of the planetary gear (11) occurs about the axis of rotation (12) thereof, a rotation of the second drive member (5) against a rotation of the planetary gear (11) about the axis of rotation (12) thereof is produced, wherein the rotation of the planetary gear (11) about the axis of rotation (12) thereof causes a relative rotation of the input shaft or output shaft (2) with respect to the adjustment member (3).