Hypocycloid Deceleration Mechanism for Compact Hydraulic Drive

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Solution Overview

Problem

Conventional hydrostatic transmission systems (HST) face challenges in achieving a sufficient deceleration ratio without increasing the overall size, particularly in the radial direction, due to the fixed configuration of electric motor output gears and sector gears, which requires larger displacement of the electric motor output shaft from the control shaft, leading to increased system size.

Innovation Solution

The hydraulic system incorporates a hypocycloid-type deceleration mechanism aligned with the drive and control shafts, reducing the size of the drive motor and preventing overall system size increase by decelerating rotary power and minimizing reaction force transmission to the drive motor, using a housing that accommodates the hydraulic rotor, output adjuster, and deceleration mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a conventional deceleration mechanism with electric motor output gear and sector gear is used, then the deceleration ratio can be increased, but the overall size of the hydraulic system increases in the radial direction

Engineering Contradiction:

Improvedeceleration ratioVSAvoidoverall system size in radial direction

Core Design Contradiction:

PowerVSArea of stationary object

Solution Approach 1:

The patent transitions from a radial deceleration mechanism to an axial arrangement by placing the hypocycloid deceleration mechanism on the same axis as the control shaft. This dimensional change allows the drive motor to be positioned coaxially with the control shaft, eliminating the need for radial displacement and reducing the overall radial size of the system while maintaining the required deceleration ratio.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent changes the type of deceleration mechanism from conventional gear-based deceleration to hypocycloid deceleration. This parameter change in the mechanism type enables achieving the same deceleration ratio with a more compact configuration that aligns with the control shaft axis, thereby reducing the radial footprint of the system.

Inventive Principle:

Principle #35Parameter changes

2Area of stationary object

If the size of the drive motor is reduced, then the overall system size can be reduced, but the driving force required to maintain the output adjuster position becomes insufficient

Engineering Contradiction:

Improvedrive motor sizeVSAvoiddriving force for output adjuster

Core Design Contradiction:

Area of stationary objectVSForce

Solution Approach 1:

The hypocycloid deceleration mechanism acts as an intermediary between the drive motor and the control shaft. It not only provides deceleration to increase torque but also serves as a reaction force absorber, preventing unwanted rotation of the control shaft. This intermediary function allows a smaller drive motor to effectively maintain the output adjuster position by leveraging the deceleration mechanism's ability to absorb reaction forces.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The hypocycloid deceleration mechanism functions as a counterbalancing element that absorbs reaction forces generated during operation. By providing this counteracting force, the mechanism compensates for the reduced output of a smaller drive motor, enabling it to adequately maintain the position of the output adjuster despite the reduced motor size.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

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 configuration effectively reduces the size of the hydraulic system and drive motor while maintaining a sufficient deceleration ratio, lessening the driving force and electricity consumption required for maintaining the output adjuster's position, and preventing unintentional rotation of the control shaft.

Implementation Method 1

the deceleration mechanism has a hypocycloid-type deceleration mechanism disposed on the reference axis

Methodology Applied

Scientific EffectHypocycloid mechanism: Gear

Implementation Method 2

a drive motor that produces rotational power for operating the control shaft around the axis

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 3

a hydraulic rotor supported by the rotational shaft so as to be incapable of relative rotation

Methodology Applied

Scientific EffectHydraulic volume displacement: Hydraulic Press

Data Source

PatentUS10502317B2Hydraulic system and driving unit with deceleration mechanism

Publication Date: 2019.12.10 KANZAKI KOKYUKOKI MFG

AI summary

A hydraulic system according to the present invention includes a rotational shaft, a hydraulic rotor supported by the rotational shaft so as to be incapable of relative rotation, an output adjuster varying a volume of the hydraulic rotor, a control shaft tilting the output adjuster, a drive motor operating the control shaft around the axis, a drive shaft disposed on a reference axis same as the axis of the control shaft and operably driven around the axis by the drive motor, a deceleration mechanism decelerating rotary power input from the drive shaft and outputs the decelerated rotary power toward the control shaft, and a housing accommodating the hydraulic rotor, the output adjuster, and the deceleration mechanism, wherein the deceleration mechanism has a hypocycloid-type deceleration mechanism disposed on the reference axis.