JPH0596486U - Bearings for liquefied gas pump motors - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention is to increase the surface hardness and wear resistance of a bearing for a liquefied gas pump motor. [Structure] The ion-nitrided layers 101 and 201 are formed on the outer ring 10 and the inner ring 20 of the bearing, and the chrome-plated layers 102 and 202 are formed on the raceways of the nitrided layers.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a bearing for a liquefied gas pump motor which is operated and operated by using a liquefied gas such as low viscosity LNG, LPG or propane as a lubricant.

[0002]

[Prior Art]

 The liquefied gas pump motor is a submerged type pump motor in which the motor itself is submerged in the liquefied gas.It is a vertical type with built-in rolling bearings on the upper and lower sides. It has a supporting structure.

The outer ring of the rolling bearing is mounted on the housing of the motor pump body, and the inner ring is fitted to the shaft of the motor pump.

The outer ring, inner ring and rolling elements of conventional rolling bearings used for this kind of application are all made of martensitic stainless steel (SUS440C etc.) having corrosion resistance, or the rolling elements are made of high speed (tool) steel (AISI). M50) is used (see, for example, Japanese Utility Model Laid-Open No. 63-69818).

[0005]

[Problems to be solved by the device]

 In the rolling bearing for the liquefied gas motor pump described above, the following phenomenon is likely to occur depending on the operating state, that is, the rolling element that revolves around its axis by interposing between the outer ring and the inner ring may revolve. There is a radial clearance in the free side bearing, so this revolving slip is likely to occur.When this revolving slip occurs, the rolling elements and the outer and inner ring raceways are worn because low-viscosity liquefied gas is used for lubrication. To do.

In extreme cases, wavy wear occurs. Even in the stationary bearing, wavy wear may occur due to the effect of load and the liquefied gas itself having low viscosity lubrication.

The state of wear varies depending on the type of the liquefied gas, and particularly the LPG liquid (viscosity: about 0.4 centistokes) is remarkably generated and has a relatively short life.

Therefore, it is a technical subject of the present invention to reduce the wear of the rolling bearing inner / outer ring raceways or the rolling elements even under the above conditions.

[0009]

[Structure for solving problems]

 In order to solve the above technical problems, the structure of a bearing for a liquefied gas pump motor of the present invention, namely, in a rolling bearing having a plurality of rolling elements between an outer ring and an inner ring, the outer ring and the inner ring are made of steel and the outer ring is formed. And a nitride layer is formed on the surface of the inner ring by performing an ion nitriding treatment, and a hard chrome plating layer is formed on the raceways of the outer ring and the inner ring by hard chrome plating, respectively. The rolling element is made of high speed steel or silicon nitride.

[0010]

[Action]

 As described above, in order to improve the wear resistance of the outer ring and the inner ring, the outer layer and the inner ring are subjected to the ion nitriding treatment to form the nitride layer, so that the surface hardness is further improved. Since the raceway surface is hard chrome plated to form a hard plating layer, the surface hardness is improved and resistance to chemical attack (hydrogen embrittlement) due to liquefied gas during use is improved. Be done.

Further, since nitriding treatment cannot be performed on rolling elements due to the use of high-speed steel or the shape of rolling elements, silicon nitride (Si ₃ N ₄₎ having high hardness is required to further improve performance. (Ceramic) significantly reduces the wear of the bearing and provides durability.

[0012]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional front view of an outer ring of a ball bearing for a liquefied gas pump motor, and FIG. 2 is a vertical sectional front view of an inner ring of a ball bearing for a liquefied gas pump motor.

Numerals 10 and 20 are outer and inner rings of a single row deep groove ball bearing made of steel material such as high speed steel (AISI M50). The outer peripheral surfaces of the outer ring 10 and the inner ring 20 are subjected to ion nitriding treatment such as vacuum discharge. Ion nitriding layers 101 and 201 of about 50 to 100 μm are formed, and then the outer surface of the outer ring 10 on which the ion nitriding layers 101 and 201 are formed, the inner surface of the inner ring 20, and the races of the outer and inner rings 10 and 20. Hard chrome plating layers 102 and 202 of about 10 μm are formed on the surface by hard chrome plating.

Reference numeral 30 is a ball made of a steel material such as high speed steel (AISI M50) or silicon nitride (Si ₃ N ₄ ), and 40 is a cage made of a synthetic resin such as PTFE.

A pump (not shown) is integrally connected to a motor (not shown) via a shaft 60, and by the two single-row deep groove ball bearings provided above and below the shaft 60. The outer ring 10 of the ball bearing is supported by the housing 50, and the inner ring 20 is fitted on the shaft 60 on the motor side.

The handling liquid when the liquefied gas pump motor is in operation flows upward from below as indicated by arrows a and b.

Although the ball bearings are illustrated and described in the above embodiments, the present invention is not limited to this, and is applied to well-known rolling bearings such as cylindrical roller bearings and needle roller bearings.

[0018]

[Effect of the device]

 Since conventional bearings for liquefied gas pump motors use martensite stainless steel, which is highly resistant to corrosion, they have extremely low viscosities such as LNG, LPG, propane, freon and butane, and have extremely poor lubricating performance It has been found that the life of the bearing is extremely shortened because the outer and inner ring raceways and rolling elements are prone to wear in the liquid handled.

According to the present invention, in order to increase the surface hardness and wear resistance of the bearing, the outer and inner rings made of steel are ion-nitrided to have a relatively thick nitride layer of about 50 to 100 μm. The surface hardness is increased up to about HV1200 by forming a high density chrome thin film plating layer having a thickness of about 10 μm on the raceway surface of the nitrided layer, the outer diameter surface of the outer ring and the inner diameter surface of the inner ring. As a result, the desired hardness is improved and hydrogen embrittlement does not occur.

Further, the wear resistance of the bearing which has undergone the above-mentioned treatment steps is remarkably improved, the life is extended, and the raceway surface and the rolling elements are not worn, so that vibration and noise can be reduced.

In addition, it is possible to improve the resistance of the bearing to chemical attack (hydrogen embrittlement).

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of an outer ring of a ball bearing for a liquefied gas pump motor according to the present invention.

FIG. 2 is a vertical sectional front view of an inner ring of a ball bearing for a liquefied gas pump motor according to the present invention.

FIG. 3 is a half sectional view showing a state in which the ball bearing of the present invention is incorporated in a liquefied gas pump.

[Explanation of symbols]

 10: Outer ring 20: Inner ring 101, 201: Ion nitriding layer 102, 202: High density chrome plating layer 30: Ball

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location F16C 33/62 7403-3J

Claims (1)

[Scope of utility model registration request] 1. A rolling bearing having a plurality of rolling elements between an outer ring and an inner ring, wherein the outer ring and the inner ring are made of steel, and the surface of the outer ring and the inner ring is subjected to an ion nitriding treatment to form a nitride layer. Characterized in that a hard chrome plating layer is formed by further subjecting the raceways of the outer ring and the inner ring to hard chrome plating, and the rolling element is made of high speed steel or silicon nitride. Bearings for liquefied gas pump motors.