JPH0329615Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial field of application This invention is a bearing device used in automobiles and aircraft, general industrial machinery, vacuum equipment, etc. Specifically, the invention is a bearing device that is used in automobiles and aircraft, general industrial machinery, vacuum equipment, etc. This invention relates to a bearing device formed by a combination.

Conventional technology Normally, in bearings placed between two relatively rotatable mechanical members, lubricants are used to reduce friction and prevent seizing to maintain good rotational characteristics. However, when rotating at high speeds or using at high temperatures, it is extremely difficult to maintain stable rotation for a long period of time.

For this reason, rolling bearings made of ceramics such as silicon carbide and silicon nitride, which have a small coefficient of friction and excellent high-temperature properties, are attracting attention.

Problems to be solved by the invention Ceramic bearings have excellent features such as a low coefficient of friction, high wear resistance, and resistance to high temperatures. However, in a bearing device that combines a ceramic bearing and a shaft member made of a metal material, when the temperature of the equipment atmosphere in which the ceramic bearing is installed rises to a high temperature, the coefficient of thermal expansion decreases, for example, to 3×10 ^-6 / When a rolling bearing made of ceramics with a thermal expansion coefficient of 11×10 ^-6 /℃ is combined with a shaft member made of steel with a thermal expansion coefficient of 11 Since the expansion of the bearing and shaft member was large, there was a high risk that the hoop tension would act on the ceramic bearing and damage the ceramic bearing.

Moreover, a gap is formed between the ceramic bearing and the lock nut that integrally engages the ceramic bearing with the shaft member, which may damage not only the ceramic bearing but also the entire device during high-speed rotation.

Further, when the temperature conditions during operation fluctuate, and even when they do not fluctuate, during the transition period, it is inevitable that the system will experience a state of large filtration or excessive clearance depending on the initial conditions. In this case, large interference filtration may cause damage to the inner ring, and excessive clearance may cause misalignment and vibration, which may cause an accident during high-speed operation.

Means for Solving the Problems In view of the above-mentioned problems, this invention consists of a ceramic bearing fitted onto a shaft member made of a metal material, and a lock nut screwed into a threaded portion provided at the end of the shaft member. In a bearing device that integrally couples the ceramic bearing to the shaft member, a spacer made of a material having a larger thermal expansion than the shaft member, such as metal, is interposed between the inner ring of the ceramic bearing and the lock nut, The inner diameter surface of the bearing inner ring and the spacer is formed into a conical surface, and the outer surface of the shaft member and the bearing inner ring and the spacer has a cross section that substantially matches the inner diameter surface of the bearing inner ring and the spacer. A sliding member made of a synthetic resin having a special abacus shape is fitted into the shaft with a predetermined pressure applied thereto.

Effect When the bearing ambient temperature rises, the radial clearance between the inner ring of the ceramic bearing and the shaft member decreases due to the difference in thermal expansion, and the radial clearance between the spacer and the shaft member increases due to the difference in thermal expansion. As a result, the sliding member moves on the shaft member toward the spacer. Additionally, the axial distance between the ceramic bearing and the lock nut is expanded due to the difference in thermal expansion between the ceramic bearing and the shaft member.
This expansion is offset by the thermal expansion of the spacer.

Embodiment FIG. 1 is a longitudinal sectional view of a main part showing an embodiment of a bearing device according to the invention. In the drawings, reference numeral 1 denotes a rolling bearing made of ceramics such as silicon carbide or silicon nitride, and includes an inner ring 2 whose inner diameter surface 2a is formed into a conical surface, an outer ring 3, a plurality of rolling elements 4, and a cage 5.
and is fitted onto the shaft member 6. The shaft member 6 is made of a metal material, for example steel, and has a shoulder portion 6a for positioning the ceramic bearing 1, and a threaded portion 6b at the end. Reference numeral 7 denotes a spacer made of a metal material having a larger thermal expansion than the steel shaft member 6, for example, an aluminum alloy, and its inner diameter surface 7a
is formed into a conical surface symmetrical to the inner diameter surface 2a of the inner ring 2, and is fitted onto the shaft member 6 so as to butt against the inner ring 2. 8 is made from synthetic resins with self-lubricating properties such as Rulon (trade name, filler-containing fluorine resin manufactured by Yo-Bear Rulon Industries Co., Ltd.) and Merdein (trade name, filler-containing polyimide resin manufactured by Yo-Bear Rulon Industries Co., Ltd.). It is a sliding member whose outer diameter surface is the inner diameter surface 2a, 7 of the inner ring 2 and the spacer 7.
It is formed into an abacus bead shape in cross section that substantially matches the shape of the arrow a, and is fitted between the inner ring 2, the spacer 7, and the shaft member 6 in a predetermined press-contact state. A steel lock nut 9 is screwed into the threaded portion 6b of the shaft member 6 and tightened to integrally connect the ceramic bearing 1, the spacer 7, and the sliding member 8 to the shaft member 6. Note that the conical angles of the inner diameter surfaces 2a, 7a and the outer diameter surface of the sliding member 8 are determined as appropriate depending on the magnitude of the friction coefficient between them.

In the bearing device with the above structure, for example, even when the ambient temperature rises, the thermal expansion of the steel shaft member 6 is greater than that of the ceramic bearing 1, so the radial clearance between the inner ring 2 and the shaft member 6 is reduced. The ceramic bearing 1 then receives a large hoop tension via the sliding member 8, but at this time,
Since the thermal expansion of the aluminum alloy spacer 7 fitted into the shaft member 6 in a butt state with the inner ring 2 is larger than that of the shaft member 6, the radial clearance between the spacer 7 and the shaft member 6 increases. Since the sliding member 8 moves on the shaft member 6 toward the spacer 7 as shown in FIG. 2 due to the reaction force of the hoop tension against the inner ring 2,
The ceramic bearing 1 is constructed so that it is always maintained in a predetermined pressure contact state without being subjected to large hoop tensions.

Moreover, the axial distance between the ceramic bearing 1 and the lock nut 8 is the same as that between the ceramic bearing 1 and the shaft member 6.
A gap is formed in the axial direction due to the difference in thermal expansion between the ceramic bearing 1 and the lock nut 8. At this time, since the spacer 7 is interposed between the ceramic bearing 1 and the lock nut 8, the shaft member 6 The spacer 7 absorbs the thermal expansion from the inner ring 2 of the bearing 1 by thermally expanding and elongating from the shaft member 6, and the ceramic bearing 1 and the spacer 7 and the spacer 7 and the lock nut 8
There is no gap formed between the
It has a structure that always maintains a predetermined pressure contact state.

Next, when the temperature rises, the radial clearance between the spacer 7 and the shaft member 6 decreases, and the radial clearance between the inner ring 2 of the ceramic bearing 1 and the shaft member 6 increases. The sliding member 8 slides over the shaft member 6 into the inner ring 2.
Since the ceramic bearing 1 is moved to the side, the ceramic bearing 1 is always kept in a predetermined pressure contact state.

Here, a ceramic bearing 1, a spacer 7, a shaft member 6
For ceramics, aluminum alloy, and steel respectively, the thermal expansion coefficients are as follows: Ceramics: 3×10 ^-6 /℃ Aluminum alloy: 17×10 ^-6 /℃ Steel: 11×10 ^-6 /℃ The axial dimensions of members 1, 7, and 6 are l ₁ , l ₂ , and l ₃ as shown in the figure, and the temperature change of the entire device is Δt℃.
Then, l ₁ = l ₂ + l ₃ ...(1) l ₁ ×11×10 ^-6 ×Δt=l ₂ ×3×10 ^-6 ×Δt＋l ₃ ×17
×10 ^-6 ×Δt ...(2) 11l ₁ =3l ₂ +17l ₃ ...(3), and from equations (1) and 3, the relationship l ₂ /l ₃ = 3/4 holds true. Therefore, the ratio of l ₂ :l ₃ is 3:4.
If the design is such that the tightening force will not change even if the temperature of the device changes.

Effects of the invention According to this invention, the hoop tension and axial clearance caused by the difference in thermal expansion between the ceramic bearing and the metal shaft member can be reduced.
Since the spacer is made of a metal material whose thermal expansion is larger than that of the metal material of the shaft member, it is designed to absorb the thermal expansion to an acceptable extent, so the ceramic bearing simply maintains a predetermined pressure-welding state, and when rotating at high speeds or at high temperatures. It is possible to provide an extremely excellent bearing device that can be used in various conditions, and can be applied to mechanical devices that rotate at high speeds and are used in high-temperature environments.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a main part showing an embodiment of a bearing device according to this invention, and FIG. 2 is an enlarged view of a main part showing an operating state. 1... Ceramic bearing, 2... Inner ring, 2a...
Inner diameter surface, 3... Outer ring, 4... Rolling element, 5... Cage, 6... Shaft member, 7... Spacer, 7a... Inner diameter surface, 8... Sliding member.

Claims (1)

[Scope of utility model registration request] In a bearing device in which a ceramic bearing is fitted onto a shaft member made of a metal material, and the ceramic bearing is integrally coupled to the shaft member with a lock nut screwed into a threaded portion provided at an end of the shaft member, the above-mentioned A spacer made of a material having a larger thermal expansion than the shaft member is interposed between the inner ring of the ceramic bearing and the lock nut, and the inner diameter surfaces of the bearing inner ring and the spacer are formed into conical surfaces, so that the shaft member and the A sliding member made of synthetic resin having an abacus-shaped cross section whose outer surface substantially matches the inner diameter surface of the bearing inner ring and the spacer is inserted between the bearing inner ring and the spacer with a predetermined pressure contact state. Characteristic bearing device.