JP2009097645A - Rolling bearing for ammonia gas compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable rolling bearing for an ammonia gas compressor whose performance is not deteriorated even if exposed to an ammonia gas. <P>SOLUTION: A single-row cylindrical roller bearing comprises: an inner ring 1 having a raceway surface on its outside circumferential surface; an outer ring 2 having a raceway surface facing the raceway surface of the inner ring 1 on its inside circumferential surface, a plurality of rolling elements 3 arranged rotatably between these raceways, and a retainer 4 retaining the rollers 3 between these raceways. The retainer 4 is structured with a resin composition containing polyetheretherketone and glass fibers. The content of the glass fibers is 20 to 40 mass% of the resin composition. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rolling bearing incorporated in a compressor using ammonia gas as a refrigerant (hereinafter, sometimes referred to as a rolling bearing for an ammonia gas compressor).

  In compressors used for air conditioners and refrigerators, in consideration of the environment, switching to natural refrigerants is progressing. Ammonia gas, one of the natural refrigerants, is extremely environmentally friendly, with both ozone depletion potential and global warming potential zero. Therefore, the application of the ammonia gas compressor is spreading to large commercial refrigeration systems, high-efficiency heat pump chillers, and the like.

The types of rolling bearings built into compressors are mainly cylindrical roller bearings and angular contact ball bearings. However, considering the upper limit of the actual operating temperature of the compressor, 80 ° C, glass fibers are used as reinforcing fiber materials for rolling bearings. In many cases, a cage made of the polyamide 66 resin composition is incorporated.
However, although polyamide 66 is not chemically degraded by alternative chlorofluorocarbons used as refrigerants for general compressors, the amide bond present in the molecular structure is eroded by ammonia and molecules are cut, resulting in a decrease in strength. Could occur.

Therefore, linear polyphenylene sulfide having excellent resistance to ammonia has been adopted as a material for a cage incorporated in a rolling bearing for an ammonia gas compressor. That is, the cage was made of a resin composition containing glass fibers as a reinforcing fiber material in linear polyphenylene sulfide. This glass fiber is a general glass fiber having a circular cross-sectional shape and an average fiber diameter of 13 μm.
JP 2002-242940 A

  However, since the linear polyphenylene sulfide has lower toughness than the polyamide 66, there is a problem that when the rolling elements are press-fitted into the pocket when the rolling bearing is assembled, it is difficult to press-fit or the cage is cracked. there were. Therefore, in the case of polyamide 66, the glass fiber content is generally 25% by mass, but in the case of linear polyphenylene sulfide, the content is set to 20% by mass, and the tensile elongation of the resin composition is 2.3% or more. As toughness was ensured.

However, since the glass fiber content is low, the mechanical strength is slightly lower than that of the cage made of the polyamide 66 resin composition. Therefore, a rolling bearing incorporating a cage made of a linear polyphenylene sulfide resin composition has a slightly lower reliability than a rolling bearing incorporated with a cage made of a polyamide 66 resin composition, improving reliability. Was desired.
SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a rolling bearing for an ammonia gas compressor that solves the above-described problems of the prior art and has high performance with little degradation in performance even when exposed to ammonia gas.

  In order to solve the above problems, the present invention has the following configuration. That is, the rolling bearing for an ammonia gas compressor according to claim 1 of the present invention includes an inner ring, an outer ring, a plurality of rolling elements that are freely rollable between the inner ring and the outer ring, the inner ring, and the outer ring. A rolling bearing incorporated in a compressor using ammonia gas as a refrigerant, wherein the cage contains a polyetheretherketone and glass fiber. The glass fiber content is 20% by mass or more and 40% by mass or less of the resin composition.

  According to a second aspect of the present invention, there is provided a rolling bearing for an ammonia gas compressor, comprising: an inner ring, an outer ring, a plurality of rolling elements that are freely rollable between the inner ring and the outer ring; A rolling bearing that is incorporated in a compressor that uses ammonia gas as a refrigerant, wherein the cage contains a linear polyphenylene sulfide and a glass fiber. The glass fiber has a circular cross-sectional shape and an average fiber diameter of 6 μm or more and 8 μm or less, or a modified cross section, and the glass fiber content is 15% by mass of the resin composition. The content is 30% by mass or less.

  The rolling bearing for an ammonia gas compressor of the present invention is highly reliable with almost no performance degradation even when exposed to ammonia gas.

An embodiment of a rolling bearing for an ammonia gas compressor according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial longitudinal sectional view showing the structure of a single row cylindrical roller bearing which is an embodiment of a rolling bearing for an ammonia gas compressor according to the present invention. 2 is a perspective view of a cage incorporated in the cylindrical roller bearing of FIG.
The single-row cylindrical roller bearing of FIG. 1 has an inner ring 1 having a raceway surface on the outer circumferential surface, an outer ring 2 having a raceway surface facing the raceway surface of the inner ring 1 on the inner circumferential surface, and is freely rollable between these raceway surfaces. A plurality of rolling elements (cylindrical rollers) 3 arranged on the surface, and a cage 4 that holds the rolling elements 3 between the raceway surfaces.

  The cage 4 is composed of a resin composition containing polyether ether ketone (PEEK) or linear polyphenylene sulfide (L-PPS) and glass fibers. Since polyether ether ketone and linear polyphenylene sulfide have resistance to ammonia, there is almost no possibility that the strength of the cage 4 will decrease even when exposed to ammonia gas. Moreover, since polyether ether ketone and linear polyphenylene sulfide have excellent heat resistance, there is no problem even if they are used at 80 ° C. which is the upper limit of the actual use temperature of the compressor. Furthermore, since polyether ether ketone and linear polyphenylene sulfide are thermoplastic resins, the cage 4 can be manufactured by an injection molding method.

  The kind and content of the glass fiber used for this resin composition differ with the kind of thermoplastic resin. First, the case of polyether ether ketone will be described. Since polyetheretherketone has higher toughness and higher strength than linear polyphenylene sulfide, the amount (25% by mass) of glass fiber is the same as that of the polyamide 66 resin composition that is a general cage material. Even if contained, the tensile elongation of the resin composition is at a sufficient level (2.3% or more). Therefore, when the rolling element is press-fitted into the pocket of the cage, it is difficult to press-fit or the cage is hardly cracked.

  A tensile force equal to or higher than the tensile strength (155 to 165 MPa) of the polyamide 66 resin composition having a glass fiber content of 25% by mass while preventing breakage of the cage when the rolling elements are press-fitted into the pocket of the cage. In order to make it strong, it is necessary to make content of glass fiber into 20 to 40 mass% of a resin composition. If the glass fiber content is less than 20% by mass, it may be difficult to make the tensile strength equal to or higher than the tensile strength of the polyamide 66 resin composition described above. On the other hand, if it exceeds 40% by mass, the tensile strength may be increased, but the tensile elongation may be insufficient (less than 2.3%). In order to make such inconvenience less likely to occur, the glass fiber content is more preferably 25% by mass or more and 35% by mass or less of the resin composition.

  Next, the glass fiber used for a polyether ether ketone resin composition is demonstrated. The kind of glass fiber is not specifically limited, The normal glass fiber generally used as a reinforced fiber material of a thermoplastic resin can be used without a problem. For example, the cross-sectional shape is circular and the average fiber diameter is 10 μm or more and 13 μm or less, and the surface is treated with a coupling agent (for example, a silane coupling agent) in consideration of adhesiveness to the resin. However, in order to obtain sufficient tensile strength and ensure sufficient tensile elongation with a smaller amount of content, those having a circular cross-sectional shape and an average fiber diameter of 6 μm or more and 8 μm or less, or having a deformed cross section are more. preferable. If these special glass fibers are used, the tensile strength of the resin composition can be improved by 10 to 20% as compared with the case where the same amount of the above-described general glass fibers is used.

  When the former thin glass fiber is contained in the resin at the same mass ratio, the number of glass fibers acting on the polar part (for example, ether bond) of the resin is larger than that of the general glass fiber. . Therefore, mechanical strength such as tensile strength and impact strength of the resin composition is increased. In addition, since the surface area of the entire glass fiber increases as the number of glass fibers contained increases, the amount of the coupling agent adsorbed on the surface of the glass fiber increases accordingly, and the polar part of the resin The number of points of action increases.

  Examples of the glass fiber having the irregular cross-section include those having a cross-sectional shape of a bowl or an oval and an irregularity ratio (ratio of horizontal to vertical) of 1.5 to 5. If the deformed ratio is less than 1.5, the effect of improving the mechanical strength is low, and if it is more than 5, the flat shape is too large and it is difficult to stably produce glass fibers. In order to make such inconvenience less likely to occur, it is more preferable that the deformation ratio is 2 or more and 4 or less.

  The minor axis of the irregularly shaped glass fiber is preferably 5 μm or more and 12 μm or less. If the minor axis is less than 5 μm, the glass fiber is often damaged during production, and it may be difficult to produce glass fibers having low quality and stable quality. On the other hand, if the minor axis is more than 12 μm, considering the irregular cross section, the diameter is too large, and there is a risk of poor glass fiber dispersion in the molded product.

  Since the glass fiber having an irregular cross section has a strong strength for each fiber, it is difficult to break during molding of the resin composition. Therefore, the length of the glass fiber after forming becomes longer than the glass fiber having a circular cross-sectional shape. Thereby, when it contains in resin by the same mass ratio, mechanical strength, such as tensile strength and impact strength, becomes high. Further, by having a modified cross section, in addition to the reinforcing effect in the longitudinal direction of the glass fiber, a little reinforcing effect in the direction perpendicular to the longitudinal direction is also obtained, so the anisotropy of the molded product is reduced. As a result, the variation in tensile strength and dimensional change due to the orientation of the glass fiber is reduced, so it is optimal as a cage material that requires uniform physical properties. And the roundness of the inner and outer diameters of the cage is improved, and sink marks are less likely to occur on the surface. Furthermore, since the glass fiber having an irregular cross section has a flat cross section, it has a high probability of receiving a load on the surface of the molded product, and the glass fiber may be used for an application in which the cage partially has a high surface pressure. Wear is difficult to occur.

  Next, the case of linear polyphenylene sulfide will be described. Since linear polyphenylene sulfide has lower toughness than polyamide 66, it ensures a tensile elongation (2.3% or more) that prevents the cage from being damaged when the rolling elements are pressed into the cage pocket. However, in order to obtain a tensile strength equal to or higher than the tensile strength (155 to 165 MPa) of the polyamide 66 resin composition having a glass fiber content of 25% by mass, the aforementioned cross-sectional shape is circular and the average fiber diameter is 6 μm. It is necessary to use a glass fiber having a thickness of 8 μm or less or a glass fiber having an irregular cross section.

  And the content of the glass fiber in a linear polyphenylene sulfide resin composition needs to be 15 to 30 mass% of a resin composition. If the glass fiber content is less than 15% by mass, it may be difficult to make the tensile strength equal to or higher than the tensile strength of the polyamide 66 resin composition described above. On the other hand, if it exceeds 30% by mass, the tensile strength may be increased, but the tensile elongation may be insufficient (less than 2.3%). In order to make such inconvenience less likely to occur, the glass fiber content is more preferably 15% by mass or more and 25% by mass or less of the resin composition.

The glass fibers used in the polyether ether ketone resin composition and the linear polyphenylene sulfide resin composition are preferably surface-treated with a coupling agent in order to improve the adhesiveness with these thermoplastic resins. . The type of coupling agent is not particularly limited. For example, a silane coupling agent having a functional group such as an epoxy group or an amino group at one end, or a sizing agent mainly composed of an epoxy resin or a urethane resin. can give. Such a coupling agent improves the adhesion between the glass fiber and the thermoplastic resin, so that the reinforcing effect of the glass fiber is improved.
In addition, this embodiment shows an example of this invention and this invention is not limited to this embodiment. For example, in this embodiment, glass fiber is used as the reinforcing fiber material, but a part of the glass fiber may be replaced with a whisker-like material such as potassium titanate whisker or carbon fiber. Moreover, you may add a coloring agent etc. to a resin composition.

  Furthermore, in the present embodiment, a single-row cylindrical roller bearing has been described as an example of a rolling bearing for an ammonia gas compressor. However, it goes without saying that the present invention can also be applied to a double-row cylindrical roller bearing. . Furthermore, the present invention can be applied to various types of rolling bearings other than cylindrical roller bearings. For example, a deep groove ball bearing, an angular ball bearing as shown in FIG. 3 (FIG. 4 is a perspective view of a cage incorporated in the angular ball bearing), a self-aligning ball bearing, a tapered roller bearing, and a needle roller bearing. , Radial roller bearings such as self-aligning roller bearings, and thrust type rolling bearings such as thrust ball bearings and thrust roller bearings.

〔Example〕
Hereinafter, the present invention will be described more specifically with reference to examples. A resin composition composed of a thermoplastic resin and glass fiber (see Table 1 for the composition) was injection molded to produce a tensile test piece defined in ASTM D638.

  Here, the thermoplastic resin and glass fiber which were used for the resin composition of Examples 1-4 and Comparative Examples 1 and 2 are demonstrated. The linear polyphenylene sulfide of Example 1 is a base resin used in Fortron KPS T2020 manufactured by Kureha Co., Ltd. and does not contain a heat stabilizer. The glass fiber of Example 1 is T-790DE manufactured by Nippon Electric Glass Co., Ltd., and has a circular cross-sectional shape and an average fiber diameter of 6.5 μm. The glass fiber is subjected to a surface treatment with an amino silane coupling agent and a surface treatment with an epoxy sizing agent.

The linear polyphenylene sulfide of Example 2 is the same as that of Example 1. Further, the glass fiber of Example 2 is CSG3PA-820 manufactured by Nitto Boseki Co., Ltd., having a cross-sectional shape of an ellipse, a short diameter of 7 μm, and a deformed ratio of 4. The glass fiber is subjected to a surface treatment with an amino silane coupling agent and a surface treatment with a urethane sizing agent.
The resin composition of Example 3 is PEEK450GL30 manufactured by Victrex MC, and does not contain a heat stabilizer. The glass fiber used in this resin composition has a circular cross section and an average fiber diameter of 13 μm. The glass fiber is subjected to a surface treatment with an amino silane coupling agent and a surface treatment with a urethane sizing agent.

The polyether ether ketone of Example 4 is PEEK450G manufactured by Victrex MC and does not contain a heat stabilizer. Moreover, the glass fiber of Example 4 is the same as that of Example 2.
The resin composition of Comparative Example 1 is UBE nylon 2020GU550 manufactured by Ube Industries, Ltd., and contains a copper-based heat stabilizer. The glass fiber used in this resin composition has a circular cross section and an average fiber diameter of 10 μm. The glass fiber is subjected to a surface treatment with an amino silane coupling agent and a surface treatment with a urethane sizing agent.

The resin composition of Comparative Example 2 is Fortron KPS T2020 manufactured by Kureha Corporation and does not contain a thermal stabilizer. The glass fiber used in this resin composition has a circular cross section and an average fiber diameter of 13 μm. The glass fiber is subjected to a surface treatment with an amino silane coupling agent and a surface treatment with an epoxy sizing agent.
Tensile test was performed on tensile test pieces made of these resin compositions, and tensile strength and tensile elongation were measured. Furthermore, after the tensile test piece was left in an ammonia gas at 130 ° C. for 800 hours, a tensile test was performed in the same manner to measure the tensile strength. Table 1 also shows the initial tensile strength and tensile elongation, and the tensile strength after the treatment.

  Since Comparative Example 1 is a polyamide 66 resin composition, the tensile strength was significantly reduced by leaving it in ammonia gas. On the other hand, since Examples 1-4 are a polyether ether ketone resin composition and a linear polyphenylene sulfide resin composition having excellent resistance to ammonia, the tensile strength due to standing in ammonia gas is high. The decrease was slight.

In Examples 1 and 2, the glass fiber content is smaller than that of the polyamide 66 resin composition of Comparative Example 1 which is a general cage material, but the glass fiber having an irregular cross section or a glass fiber having a small average fiber diameter is used. Since the strength was increased by using the material, the tensile strength was higher than that of Comparative Example 1.
Furthermore, since Example 3 is a polyether ether ketone resin composition, it has a tensile strength equivalent to that of Comparative Example 1 even when ordinary glass fibers are used. By using glass fiber, the strength is further increased.

It is a fragmentary longitudinal cross-section which shows the structure of the single row cylindrical roller bearing which is one Embodiment of the rolling bearing for ammonia gas compressors which concerns on this invention. FIG. 2 is a perspective view of a cage incorporated in the cylindrical roller bearing of FIG. 1. It is a fragmentary longitudinal cross-section which shows the structure of the angular ball bearing which is another embodiment of the rolling bearing for ammonia gas compressors which concerns on this invention. FIG. 4 is a perspective view of a cage incorporated in the angular ball bearing of FIG. 3.

Explanation of symbols

1 Inner ring 2 Outer ring 3 Rolling element 4 Cage

Claims (2)

An inner ring, an outer ring, a plurality of rolling elements arranged to roll between the inner ring and the outer ring, and a cage for holding the rolling element between the inner ring and the outer ring, and ammonia gas In rolling bearings incorporated in compressors that use
The cage is composed of a resin composition containing polyether ether ketone and glass fiber, and the content of the glass fiber is 20% by mass or more and 40% by mass or less of the resin composition. Rolling bearing for ammonia gas compressor. An inner ring, an outer ring, a plurality of rolling elements arranged to roll between the inner ring and the outer ring, and a cage for holding the rolling element between the inner ring and the outer ring, and ammonia gas In rolling bearings incorporated in compressors that use
The cage is made of a resin composition containing linear polyphenylene sulfide and glass fiber, and the glass fiber has a circular cross-sectional shape and an average fiber diameter of 6 μm to 8 μm or a modified cross section. A rolling bearing for an ammonia gas compressor, wherein the glass fiber content is 15% by mass or more and 30% by mass or less of the resin composition.

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