JPH04119225A - Slide bearing - Google Patents

Abstract

PURPOSE:To prevent relative rotation between members and avoid decrease of bearing function so as to extend the service life of bearing by pressure inserting an inner cylinder brought into face contact with a rotary shaft on its inner circumferential face in an intermediate cylinder, constructing a three- layered structure where an outer cylinder is shrinkage fitted to this intermediate cylinder, while setting properly the Young's modulas of the inner cylinder. CONSTITUTION:A sliding bearing 1 has a three-layered structure of an inner cylinder 3 made of ceramics such as silicon carbonate or silicone nitride to be bought into slide contact with a rotary shaft 2 on its inner face, an intermediate cylinder 4 into which the inner cylinder 3 is presure fitted and an outer cylinder 5 shrinkage fitted to the intermediate cylinder 4. The thermal expansion coefficients of inner, intermediate and outer cylinder alpha1, alpha2, alpha3 have a relation of alpha2>alpha3>alpha1 while the Young's moduli E1, E2, E3 thereof have a relation of E2>E3>E1. A thermal expansion absorbing groove 6 of the intermediate cylinder 4 is formed at the inner circumference 5a of the outer cylinder 5, that is the shrinkage fitted face 5a.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides 1 for example bearings of indoor shaft pumps, which are lubricated and cooled by self-pumped water during pumping operation, and are lubricated and cooled by self-pumped water during dry operation. Regarding sliding bearings that can support the main shaft (rotating shaft) with lubrication and cooling cut off, the bearing function deteriorates even if the bearing temperature rises due to external factors such as frictional heat during dry operation. This relates to a sliding bearing designed to prevent

[Conventional technology] Like the bearings of indoor shaft pumps, the main shaft is pivotally supported while being lubricated and cooled by self-pumped water for stable operation, and during dry operation, the lubrication and cooling by self-pumped water are cut off. A ceramic bearing shown in FIG. 2 is generally used as a bearing that supports the main shaft in a stable state and allows stable operation.

This sliding bearing consists of a ring-shaped or segment-shaped ceramic inner cylinder lO and a stainless steel outer cylinder (shell).
A cylindrical bearing body is constructed by shrink-fitting and fixing 2.

[Issue to be Solved by the Invention 111 However, the conventional sliding bearing has a two-layer structure in which the outer cylinder 20, which has a large coefficient of thermal expansion, is shrink-fitted to the inner cylinder 10, which has a small coefficient of thermal expansion. When the temperature rises due to frictional heat during operation, the outer cylinder 20 expands at a higher rate than the inner cylinder, and the holding force of the outer cylinder 20 on the inner cylinder IO becomes smaller.

Therefore, relative rotation occurs between the two 10.20, which deteriorates the bearing function.

Specifically, even if the shrink fit is performed with a large cooling shrinkage allowance (hereinafter simply referred to as shrinkage allowance) such that the shrink fit stress reaches the limit tolerance value of 10.20, the inner cylinder 10 and the outer cylinder When the temperature of 20 rises to about 100°C, the shrinkage allowance disappears, and the holding force of the inner cylinder 10 by the outer cylinder 20 becomes extremely small, causing relative rotation between the two 10 and 20, which deteriorates the bearing function. It has been confirmed that

The present invention was developed in view of these circumstances, and even if the temperature rises due to external causes such as frictional heat during dry operation, by ensuring a large holding force, relative rotation between members is prevented, and the bearing function is maintained. The purpose of the present invention is to provide a sliding bearing that can prolong its life by avoiding a decrease in

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention press-fits an inner cylinder whose inner peripheral surface is in surface contact with a rotating shaft into an intermediate cylinder, and shrink-fits an outer cylinder to the intermediate cylinder. In addition, the relationship among the thermal expansion coefficient αl of the inner cylinder, the thermal expansion coefficient α2 of the intermediate cylinder, and the thermal expansion coefficient α3 of the outer cylinder is set to α2>α3>α1, and the Young The relationship among the modulus E, the Young's modulus E2 of the intermediate cylinder, and the Young's modulus E3 of the outer cylinder is set to satisfy E2 < E3 < E.

In some cases, grooves for absorbing thermal expansion of the intermediate cylinder are formed on the shrink-fitting surface of the outer cylinder.

[Function] According to the present invention, when the temperature of the inner cylinder, intermediate cylinder, and outer cylinder increases due to external causes such as frictional heat during dry operation,
The diameter expansion of the intermediate cylinder, which has the highest coefficient of thermal expansion, is suppressed by the outer cylinder, which has a lower coefficient of thermal expansion and a larger Young's modulus.

By suppressing expansion and diameter expansion of the intermediate cylinder, a reaction force is generated in the diameter reduction direction, and this reaction force tightens the inner cylinder. In other words, even when the temperature rises, the intermediate cylinder can be designed to tighten the inner cylinder with a tightening force that is approximately equal to the cooling shrinkage force after shrink fitting, so the holding force of the inner cylinder by the intermediate cylinder does not decrease, so the thermal expansion coefficient Even if the inner cylinder is made of a material that has a property of low expansion and diameter expansion, relative rotation with the intermediate cylinder will be prevented.

In addition, by suppressing the expansion and expansion of the intermediate cylinder with the outer cylinder, it is possible to design the outer cylinder to tighten the intermediate cylinder with a tightening force that is approximately equal to the cooling contraction force after shrink fitting. Since the holding force of the cylinder does not decrease, relative rotation between the outer cylinder and the intermediate cylinder is also prevented.

By forming a thermal expansion absorbing groove on the shrink-fitting surface of the outer cylinder, excessive expansion of the intermediate cylinder at high temperatures is absorbed and the generation of excessive stress is prevented.

[Example] An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a half-cut vertical cross-sectional view showing an embodiment of the present invention;
In this figure, the sliding bearing 1 includes an inner cylinder 3 made of ceramic such as silicon carbide or silicon nitride whose inner peripheral surface is in sliding contact (surface contact) with the rotating shaft 2, and a cylinder 3 made of duralumin, for example, into which the inner cylinder 3 is press-fitted. The intermediate cylinder 4 and the intermediate cylinder v
It has a three-layer structure consisting of an outer cylinder 5 made of stainless steel, for example, which is shrink-fitted to the I4.

Therefore, the thermal expansion coefficient αl of the inner cylinder 3, the thermal expansion coefficient α2 of the intermediate cylinder 4, and the thermal expansion coefficient α3 of the outer cylinder 5 are α2>
They have the relationship α3>α1, and the Young's modulus E1 of the inner cylinder 3, the Young's modulus E2 of the intermediate cylinder 4, and the Young's modulus E3 of the outer cylinder 5.
has the relationship E2 < E3 < El.

Thermal expansion absorbing grooves 6 of the intermediate cylinder 4 may be formed on the inner circumferential surface 5a of the outer cylinder 5, that is, the shrink fit surface 5a.

With such a configuration, the inner cylinder 3. When the temperature of the intermediate cylinder 4 and the outer cylinder 5 rises, they expand and expand in diameter with the relationship: [intermediate cylinder 4>outer cylinder 5>inner cylinder 3''.

However, the expansion and diameter expansion of the intermediate cylinder 4 is suppressed by the outer cylinder 5 having a lower coefficient of thermal expansion than this. For this purpose, the intermediate cylinder 4
Due to the relationship E2 < E3 < El, a reaction force is generated in the diameter reduction direction, and the inner cylinder 3 is tightened by this reaction force.

That is, the shrinkage allowance does not disappear even when the temperature rises, and the intermediate cylinder 4 tightens the inner cylinder 3 with a tightening force that is approximately equal to the cooling shrinkage force after shrink fitting.

Therefore, the inner cylinder 3 is held with a high holding force, so even if the inner cylinder 3 is made of a material such as ceramics, which has a low coefficient of thermal expansion and a characteristic of small expansion and diameter expansion,
Since relative rotation with the intermediate cylinder 4 is prevented, deterioration of the bearing function can be avoided and the life of the sliding bearing 1 can be extended.

Further, by suppressing expansion and diameter expansion of the intermediate cylinder 4 by the outer cylinder 5, the outer cylinder 5 tightens the intermediate cylinder 4 with a tightening force that is approximately equal to the cooling contraction force after shrink fitting. therefore,
Since the intermediate cylinder 4 is held with a high holding force by the outer cylinder 5,
Relative rotation between the outer cylinder 5 and the intermediate cylinder 4 is prevented, and from this point as well, deterioration in bearing function can be avoided and the life of the slide bearing 1 can be extended.

Furthermore, the thermal expansion absorbing grooves 6 formed in the shrink fit surface 5a of the outer cylinder 5 can absorb excessive expansion of the intermediate cylinder 4 at high temperatures. It is possible to prevent problems such as excessive stress occurring in each of the intermediate cylinder 4 and the outer cylinder 5, causing the sliding bearing 1 to be destroyed. That is, by forming the thermal expansion absorbing groove 6 on the shrink-fitting surface 5a of the outer cylinder 5, high-temperature destruction of the sliding bearing 1 can be prevented and life extension can be achieved.

[Effects of the Invention] Since the present invention is configured as described above, it produces the following effects.

In other words, even if the temperature of the inner cylinder, intermediate cylinder, and outer cylinder increases due to external factors such as frictional heat during dry operation, the intermediate cylinder will hold the inner cylinder due to the large holding force, and the outer cylinder will hold the intermediate cylinder. Therefore, relative rotation between the three members is prevented, deterioration of the bearing function is avoided, and the life of the sliding bearing can be extended.

Furthermore, the thermal expansion absorbing grooves can also prevent high-temperature destruction of the sliding bearing and contribute to extending its life.

[Brief explanation of drawings]

FIG. 1 is a half-cut longitudinal sectional view showing an embodiment of the present invention, and FIG. 2 is a half-cut longitudinal sectional view of a conventional example. 1... Sliding bearing 2... Rotating shaft 3... Inner cylinder 4... Intermediate cylinder 5... Outer cylinder 5a... Shrink fit surface of outer cylinder 6... Thermal expansion of intermediate cylinder Absorption groove patent applicant Kubota Co., Ltd. Agent
Patent Attorney Takashi Suzue - Figure Figure

Claims (2)

[Claims] (1) The inner cylinder, whose inner peripheral surface is in surface contact with the rotating shaft, is press-fitted into the intermediate cylinder, and the outer cylinder is shrink-fitted to the intermediate cylinder to form a three-layer structure. The relationship between the thermal expansion coefficient α_2 of the intermediate cylinder and the thermal expansion coefficient α_3 of the outer cylinder is α_2>α.
_3>α_1, and Young's modulus of the inner cylinder E_1,
A sliding bearing characterized in that the relationship between the Young's modulus E_2 of the intermediate cylinder and the Young's modulus E_5 of the outer cylinder is set to E_2<E_3<E_1. (2) The sliding bearing according to claim 1, wherein a thermal expansion absorbing groove of the intermediate cylinder is formed on the shrink-fitting surface of the outer cylinder.