Viscous friction clutch valve control system

The electromagnetic control system for viscous friction clutches addresses design limitations by using a magnetic flux path through the rotor, enabling a compact and lightweight clutch package with improved efficiency and flexibility, particularly for 'live' center shaft applications.

JP7735317B2Active Publication Date: 2025-09-08HORTON INC
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Patent Information

Application Number
JP2022568694
Authority / Receiving Office
JP · JP
Patent Type
Patents
Current Assignee / Owner
Priority Date
2020-05-14
Filing Date
2021-04-20
Publication Date
2025-09-08
Estimated Expiration
2041-04-20

AI Technical Summary

Technical Problem

Existing viscous friction clutches face challenges in design flexibility, weight, and efficiency due to mechanical connections and embedded flux guides, which limit the development of compact and lightweight clutch packages, particularly in applications requiring a 'live' center shaft.

Method used

An electromagnetic control system for viscous friction clutches that eliminates mechanical connections and embedded flux guides by using a magnetic flux path extending through the rotor, with a ferromagnetic material guiding magnetic flux across both ferromagnetic and non-ferromagnetic components within the clutch housing.

Benefits of technology

This design achieves a compact, lightweight clutch package that efficiently operates with lower magnetic flux requirements, suitable for applications with a 'live' center shaft, enhancing design flexibility and reducing leakage risks.

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Abstract

The viscous friction clutch (100; 200) comprises a rotor (106; 206), a housing (112; 212) rotatable relative to the rotor, an actuation chamber (115; 215) disposed between the rotor and the housing, capable of selectively introducing a predetermined amount of shear fluid so that the shear fluid contacts both the rotor and the housing, an electromagnetic coil (101; 201), a valve assembly (107; 207) for controlling the amount of shear fluid held in the actuation chamber, and a magnetic flux path (A; A') magnetically connecting the electromagnetic coil and the valve assembly. The magnetic flux path passes through a magnetic flux guide portion (105; 105'; 205) made of a ferromagnetic material extending through the rotor inside the viscous friction clutch, and crosses a magnetic flux gap (B) that traverses both the air gap and the non-ferromagnetic portion (112b-1; 212b-1) of the housing.
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