KR-20260064718-A - Magnetic viscous fluids and mechanical devices

Abstract

A magnetic viscous fluid and mechanical device are provided that have low viscosity when unexcited, good drag when excited, and improved lubricity. The magnetic viscous fluid comprises magnetic particles and a dispersion medium, wherein the dispersion medium comprises a base oil and a double-chain higher fatty acid ester-modified silicone oil, and/or a side-chain higher fatty acid ester-modified silicone oil.

Inventors

• 이시자키 히로히사
• 오치아이 아키라

Assignees

• 소마아루 가부시끼가이샤

Dates

Publication Date

20260507

Application Date

20241029

Priority Date

20231110

Claims (6)

1. It includes magnetic particles and a dispersion medium, The above dispersion medium is a self-viscous fluid comprising a base oil, a double-chain higher fatty acid ester-modified silicone oil, and/or a side-chain higher fatty acid ester-modified silicone oil.
2. In paragraph 1, A self-viscous fluid in which the higher fatty acid in the above-mentioned double-chain higher fatty acid ester-modified silicone oil and the side-chain higher fatty acid ester-modified silicone oil is a saturated fatty acid having 13 to 20 carbon atoms and/or an unsaturated fatty acid having 13 to 20 carbon atoms.
3. In paragraph 1, A self-viscous fluid in which the higher fatty acid ester in the above-mentioned double-chain higher fatty acid ester modified silicone oil and the side-chain higher fatty acid ester modified silicone oil is a fatty acid ester composed of a saturated fatty acid having 13 to 20 carbon atoms and/or an unsaturated fatty acid having 13 to 20 carbon atoms and a methyl group.
4. In paragraph 1, A magnetic viscous fluid in which the total content of the above two-chain higher fatty acid ester modified silicone oil and the above-mentioned side-chain higher fatty acid ester modified silicone oil is 0.8 to 10 mass% with respect to the total amount of the magnetic viscous fluid.
5. In paragraph 1, In addition, a self-viscous fluid containing an anti-wear agent.
6. A mechanical device using a magnetic viscous fluid as described in any one of paragraphs 1 to 5.

Description

Magnetic viscous fluids and mechanical devices The present invention relates to a magnetic viscous fluid and a mechanical device. In particular, it relates to a magnetic viscous fluid and a mechanical device used to control frictional forces acting between objects in various mechanical devices, such as brakes, clutches, anti-vibration devices, and dampers of anti-vibration devices. Magneto-rheological (MR) fluids are fluids in which magnetic particles, such as magnetizable metal particles, are dispersed in a dispersion medium. In the absence of a magnetic field, the magnetic particles in a magneto-rheological fluid float randomly within the dispersion medium and function as a fluid. However, when a magnetic field is applied, the magnetic particles form numerous clusters and thicken, thereby increasing internal stress. Magnetoviscous fluids function like a rigid body due to the increase in internal stress described above, and exhibit drag against shear flow or pressure flow. Because of these characteristics, magnetoviscous fluids are used to control frictional forces acting between objects in various mechanical devices such as brakes, clutches, anti-vibration devices, and dampers of anti-vibration devices. For this reason, when a magnetic field is not applied to the magnetic viscous fluid (unexcited), a small drag resistance (viscous resistance) is required, so it is desirable for the viscosity of the magnetic viscous fluid to be low. On the other hand, when a magnetic field is applied to the magnetic viscous fluid (excited), it is desirable for the drag force against shear flow or pressure flow (hereinafter also referred to as "drag force during excitation") to be large. Furthermore, the drag force during excitation is evaluated by measuring torque values, viscosity, shear stress, etc. In this specification, the drag force during excitation is evaluated by measuring the viscosity during excitation. Patent Document 1 proposes that a magnetic viscous fluid is formed by including a predetermined amount of magnetic particles, a clay mineral-based dispersion stabilizer, and a surfactant in a carrier fluid. Hereinafter, embodiments of the magnetic viscous fluid and mechanical device of the present invention will be described, but the present invention is not to be interpreted as being limited thereto, and various changes, modifications, and improvements can be added based on the knowledge of those skilled in the art without departing from the scope of the present invention. Furthermore, in this specification, "to" indicating a numerical range indicates a range that includes the values described as the upper and lower limits, respectively. Additionally, if only the unit of the upper limit is described in the numerical range, it means that the lower limit also has the same unit as the upper limit. In the numerical ranges described stepwise in this specification, an upper or lower limit value described in any numerical range may be substituted with an upper or lower limit value of another numerical range described stepwise. In addition, regarding the numerical ranges described in this specification, any upper or lower limit value described in any numerical range may be replaced with the value shown in the example. In this specification, the content ratio or content of each component in the composition refers to the content ratio or content of the total of the corresponding multiple types of substances present in the composition, unless otherwise specifically determined, in cases where multiple types of substances corresponding to each component exist in the composition. (Magnetic Viscous Fluid) The magnetic viscous fluid according to the present embodiment comprises magnetic particles and a dispersion medium, wherein the dispersion medium comprises a base oil and a higher fatty acid ester-modified silicone oil. With this composition, the magnetic viscous fluid according to the present embodiment has low viscosity when unexcited and possesses good drag when excited, while also improving lubricity. Below, each component included in the magnetic viscous fluid according to the present embodiment will be described. 1. Magnetic particles The magnetic particles included in the magnetic viscous fluid according to the present embodiment can be selected according to the desired permeability. Examples include ferromagnetic oxides such as magnetite, carbonyl iron, γ-iron oxide, manganese ferrite, cobalt ferrite, or complex ferrites of these with zinc and nickel or barium ferrite; ferromagnetic metals such as iron, cobalt, and rare earth elements; metals of nitride; and various alloys such as Sendust (registered trademark), Permalloy (registered trademark), and Supermalloy (registered trademark). Among these, carbonyl iron is preferred as it is a soft magnetic material with low coercivity and high permeability. Carbonyl iron is a high-purity metal particle produced by the thermal decomposition of pentacarbonyl iron (Fe(CO) ₅ ).