CN-118369739-B - Magnetically viscous fluid and mechanical device

Abstract

The invention provides a magnetic viscous fluid and a mechanical device which are capable of improving resistance and rubber resistance during excitation. The magnetic viscous fluid comprises magnetic particles and base oil, wherein the base oil comprises ester base oil and nonpolar base oil, and the nonpolar index of the base oil is in the range of 10-45.

Inventors

• Ishizaki Hiroku
• LUO HEMING

Assignees

• 索马龙株式会社

Dates

Publication Date

20260512

Application Date

20231101

Priority Date

20221118

Claims (4)

1. 1. A magnetically viscous fluid comprising magnetic particles and a base oil, wherein, The base oil comprises an ester base oil and a nonpolar base oil, The ester base oil is at least one selected from hindered esters and dibasic acid esters, The content of the nonpolar base oil contained in the magnetic viscous fluid is 3-20% by mass, The base oil has a nonpolar index in the range of 10 to 45.
2. 2. The magnetically viscous fluid of claim 1, further comprising: Alkylbenzene having an alkyl group having 10 to 24 carbon atoms and/or alkylnaphthalene having an alkyl group having 10 to 24 carbon atoms.
3. 3. The magnetically viscous fluid of claim 1, further comprising: An inorganic cation exchanger having a siloxane bond, and a silicone oil.
4. 4. A mechanical device using the magnetically viscous fluid according to any one of claims 1 to 3.

Description

Magnetically viscous fluid and mechanical device Technical Field The present invention relates to a magnetically viscous fluid and a mechanical device. And more particularly, to a magnetic viscous fluid for controlling friction between objects acting on a mechanical device and a mechanical device using the same. Examples of the mechanical device include a brake, a clutch, a vibration isolator, and a damper of a vibration damper. Background The magnetic viscous (Magneto Rheological: MR) fluid is a fluid in which magnetized metal particles, that is, magnetic particles, are dispersed in a dispersion medium. In the case of a magnetically viscous fluid, when no magnetic field is applied, the magnetic particles are randomly suspended in a dispersion medium and function as a fluid. On the other hand, when a magnetic field is applied, the magnetically viscous fluid is thickened by the formation of a plurality of clusters of magnetic particles, and the internal stress increases. The magneto-viscous fluid functions as a rigid body due to the increase in the internal stress, and exhibits resistance to shear flow and pressure flow. Since the magnetic viscous fluid has such characteristics, it is used for controlling friction force acting between objects in various mechanical devices such as a brake, a clutch, a vibration isolator, and a damper of a vibration damper. Therefore, it is preferable that the magnetic viscous fluid has a large resistance to a shear flow and a pressure flow (hereinafter, also referred to as "resistance at exciting") when subjected to a magnetic field (at exciting). The resistance at the time of excitation was evaluated by measuring a moment value, viscosity, shearing stress, or the like. In the present specification, the exciting resistance is evaluated by measuring the exciting viscosity. The magneto-viscous fluid has various characteristics such as the above-described resistance at the time of excitation. In recent years, a technique has been developed that achieves improvement of various characteristics of a magnetically viscous fluid by preparing a dispersion medium of the magnetically viscous fluid. As such a technique, patent document 1 discloses a magnetic viscous fluid composition in which monoester, magnetic particles, a dispersant, and a rheology control agent are blended. It is also described that, according to such a constitution, it is possible to provide a magnetic viscous fluid composition which has low viscosity in the absence of a magnetic field, is suppressed in evaporation amount, and is excellent in fluidity at low temperatures. Patent document 2 discloses a magnetically viscous fluid in which the specific gravity and the kinematic viscosity of a dispersion medium are controlled to specific ranges and the average primary particle diameter, density, and mass ratio of magnetic particles are controlled to specific ranges. It is also described that, according to such a constitution, it is possible to provide a magnetic viscous fluid capable of greatly suppressing sedimentation of magnetic particles without changing the kinematic viscosity of a dispersion medium. Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2017-92119 Patent document 2 Japanese patent application laid-open No. 2021-163969 Disclosure of Invention Problems to be solved by the invention In various mechanical devices such as brakes, clutches, vibration isolators, dampers of vibration dampers, and the like using a magnetically viscous fluid, rubber is used as a sealing material such as an O-ring, an oil seal, and a gasket. At this time, the rubber comes into contact with the magnetically viscous fluid, and the rubber may be degraded from the contact portion by the dispersion medium contained in the magnetically viscous fluid. If the rubber used for sealing materials such as O-rings, oil seals, gaskets and the like is deteriorated, malfunction of the mechanical device may occur. Therefore, the magnetic viscous fluid is required to have a property of suppressing deterioration of rubber (hereinafter also referred to as rubber resistance property) in addition to enhancing resistance at the time of excitation. However, there is no conventional technique for improving both the resistance at the time of excitation and the rubber resistance. The present invention has been made in view of the above-described problems, and an object thereof is to provide a magnetic viscous fluid and a mechanical device that combine improvement of resistance and improvement of rubber resistance at the time of excitation. Solution for solving the problem The present invention solves the above problems, and is specifically (1) to (5) below. (1) A magnetically viscous fluid comprises magnetic particles and base oil, wherein the base oil comprises ester base oil and nonpolar base oil, and the nonpolar index of the base oil is in the range of 10-45. (2) The magnetically viscous fluid according to