JP2006250237A - Sealed rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed rolling bearing capable of stabilizing slide contact torque of a contact seal at a low level and completely preventing moisture from permeating a bearing space while allowing prevention of deterioration in sealing performance due to adhesion of mud water. <P>SOLUTION: A bearing space between an inner ring 1 and an outer ring 2 is sealed with contact seals 5, 6. Grease A whose water resistance in water-washing specified in JIS K-2220 is 2% or lower is sealed between two inner and outer contact seals 5, 6. While allowing the prevention of deterioration in sealing performance due to adhesion of mud water, the slide contact torque of the contact seal 6 on the outside is stabilized at a low level. Moreover, the permeation of moisture in the bearing space can be completely prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hermetic rolling bearing in which a bearing space between an inner ring and an outer ring is sealed with a contact seal.

  Rolling bearings used in an environment where dust, water, etc. are scattered have sealed rolling bearings in which the bearing space is sealed with a contact seal in order to prevent them from entering the bearing space between the inner ring and the outer ring. It is used. The contact seal seals the bearing space by bringing a lip formed of an elastic member such as rubber into contact with a seal sliding contact surface of an inner ring or an outer ring.

  This type of sealed-type rolling bearing is provided with one contact seal on each side of the bearing space (see, for example, Patent Document 1), or on the outside of the contact seals installed one by one. Some have a contact shield (see, for example, Patent Documents 2 and 3). In what is described in Patent Document 2, a shield (shielding plate) is divided into one attached to an inner ring and one attached to an outer ring, and a labyrinth gap is formed between these divided shields. Moreover, in what was described in patent document 3, the labyrinth clearance gap was formed between the shield (cover) and the inner contact seal.

  On the other hand, since the rolling bearing used for the center axis | shaft support part of a propeller shaft of a motor vehicle, the joint axis | shaft support part of a drive shaft, etc. is arrange | positioned under the floor part of a vehicle, it receives scattering of muddy water and rain water.

Japanese Utility Model Publication No. 7-10555 (Fig. 1) No. 8-3710 (Figs. 1 and 2) JP 2001-50288 A (Figs. 1, 3 to 10)

  When a sealed rolling bearing such as that described in Patent Document 1 is used in a portion that receives the scattering of muddy water as described above, the scattered muddy water adheres to the sliding contact portion of the contact seal, and lip or There is a problem that the seal sliding contact surface is worn and the sealing performance is remarkably lowered.

  The sealed rolling bearings described in Patent Document 2 and Patent Document 3 can prevent muddy water from directly adhering to the sliding contact portion of the contact seal by the shield, but since the shield has a non-contact gap portion, The gap penetrates between the shield and the contact seal through the labyrinth gap. In this way, the muddy water that has entered between the shield and the contact seal increases in the concentration of the mud due to the evaporation of moisture, so if the muddy water with the increased concentration of the mud adheres to the sliding contact portion of the contact seal, Wear of the seal sliding contact surface is promoted. For this reason, it is not possible to sufficiently prevent a decrease in sealing performance.

  In order to solve such a problem, the present inventor seals the bearing space with the inner and outer contact seals, blocks the scattered muddy water with the outer contact seal, and makes the muddy water on the sliding contact portion of the inner contact seal. A sealed-type rolling bearing that has been prevented from adhering has been proposed (Japanese Patent Application No. 2005-29116).

  In such a sealed rolling bearing in which the bearing space is sealed with the two inner and outer contact seals, deterioration of the sealing performance due to adhesion of muddy water can be prevented, but the oil content of the lubricant sealed in the bearing space is reduced by the outer contact seal. Since it is difficult to be supplied to the sliding contact portion, there is a problem that the frictional resistance at the sliding contact portion of the outer contact seal increases, the sliding contact torque accompanying the sliding contact of the outer contact seal increases, and becomes unstable. Further, even in the case of having two contact seals on the inside and outside in this way, moisture such as muddy water and rainwater soaks into the contact interface with the seal sliding surface of the contact seal due to capillary action, so that the bearing space of these moisture There are also problems that cannot be completely prevented.

  Therefore, the problem of the present invention is that it is possible to prevent deterioration of the sealing performance due to adhesion of muddy water, the sliding contact torque of the contact seal can be stabilized at a low level, and moisture can be completely prevented from entering the bearing space. It is to provide a sealed rolling bearing that can be used.

  In order to solve the above-described problems, the present invention provides a sealed type in which a bearing space between an inner ring and an outer ring is sealed with a contact seal that makes a lip formed of an elastic member contact a seal sliding contact surface provided on the inner ring or the outer ring. In a rolling bearing, the bearing space is hermetically sealed with two inner and outer contact seals, and between the inner and outer two contact seals, a grease having a water resistance of 2% or less as specified in JIS K-2220 is enclosed. It was adopted.

  That is, by sealing the bearing space with two inner and outer contact seals, the outer contact seal shuts off the muddy water and prevents the muddy water from adhering to the sliding contact portion of the inner contact seal to prevent deterioration of the sealing performance. Then, by enclosing grease between these two contact seals, sufficient grease is supplied to the sliding contact portion of the outer contact seal which is hard to be supplied with the lubricant contained in the bearing space. The frictional resistance at the contact portion is reduced to stabilize the sliding contact torque of the contact seal, and the grease sealed between the contact seals has a water resistance of 2% or less, preferably 1 according to JIS K-2220. By making it less than 5%, this grease can be used as a grease seal against moisture that enters from the contact interface with the seal sliding contact surface of the contact seal. It was to be able to prevent. Note that the grease sealed between the contact seals also has an effect of reducing wear at the sliding contact portion of the outer contact seal.

  The water resistance of the grease specified in JIS K-2220 represents the resistance to the grease being washed away by water and the tendency of emulsification and separation. It is expressed as a percentage of the mass of the sample that flows out after 1 hour when water of 79 ° C. is jetted while rotating. The reason why the water resistance of the grease is 2% or less, preferably 1.5% or less is that when the water resistance of the water wash exceeds 2%, the amount of grease flowing out due to contact with external water increases. This is because the role as a seal becomes insufficient and it becomes impossible to prevent moisture from entering the bearing space.

  Of the two inner and outer contact seals, the lip of the outer contact seal is brought into contact with the seal sliding contact surface provided on the inner peripheral surface of the outer ring, whereby the grease sealed between the two contact seals is Since the centrifugal force accompanying the rotation moves a lot toward the inner peripheral surface side of the outer ring, the grease can be more sufficiently supplied to the sliding contact portion of the outer contact seal.

  The hermetic rolling bearing of the present invention seals the bearing space with two inner and outer contact seals, and the water washing resistance specified by JIS K-2220 is 2% or less, preferably between these two inner and outer contact seals. Since 1.5% or less of grease is sealed, it is possible to prevent deterioration of the sealing performance due to adhesion of muddy water, to stabilize the sliding contact torque of the contact seal low, and to allow moisture to enter the bearing space. It can be completely prevented. Further, the grease sealed between the two contact seals has an effect of reducing wear at the sliding contact portion of the outer contact seal.

  Of the two inner and outer contact seals, the lip of the outer contact seal is brought into contact with the seal sliding contact surface provided on the inner peripheral surface of the outer ring, whereby the grease sealed between the two contact seals is Since the centrifugal force accompanying the rotation moves a lot toward the inner peripheral surface side of the outer ring, the grease can be more sufficiently supplied to the sliding contact portion of the outer contact seal.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, this sealed rolling bearing is a ball bearing in which a bearing space in which a ball 3 is held by a cage 4 between an inner ring 1 and an outer ring 2 is sealed with two inner and outer contact seals 5 and 6. It is.

  As shown in FIG. 2, each of the contact seals 5 and 6 includes cored bars 5a and 6a and elastic members 5b and 6b, respectively. The inner contact seal 5 is fixed to an engaging groove 2b provided on the inner peripheral surface of the outer ring 2 by an elastic member 5b, and its lip 5c contacts a seal sliding contact surface 1a provided on the outer peripheral surface of the inner ring 1. The outer contact seal 6 is fixed by fitting a cored bar 6a to a stepped portion 1b provided on the outer peripheral surface of the inner ring 1, and a lip 6c provided on the inner peripheral surface of the outer ring 2. It is in contact with the contact surface 2a. The outer contact seal 6 has a sufficiently large lip tightening margin so that a gap is not opened even if the sliding contact portion is worn due to adhesion of muddy water. Therefore, the muddy water scattered around does not reach the inner contact seal 5, and wear due to muddy water adhering to the sliding contact portion of the lip 5c is prevented.

  Grease A is sealed between the inner and outer contact seals 5 and 6, and grease B as a lubricant is also sealed in the bearing space. The grease A enclosed between the two contact seals 5 and 6 moves to the inner peripheral surface side of the outer ring 2 by a centrifugal force accompanying the rotation of the bearing, and the outer contact where the grease B in the bearing space is difficult to be supplied. Sufficient grease A is supplied to the sliding contact portion between the lip 6 c of the seal 6 and the seal sliding contact surface 2 a on the inner peripheral surface of the outer ring 2. Therefore, the frictional resistance at the sliding contact portion of the outer contact seal 6 can be reduced, and the bearing torque can be stabilized low.

  The grease A sealed between the two contact seals 5 and 6 has a water resistance of 2% or less so that it will not flow out even if it contacts external water. It serves to stop moisture entering from the contact interface between the seal 6 and the seal sliding contact surface 2a. It also serves to reduce wear at the sliding contact portion of the outer contact seal 6.

Sealed rolling bearings (Examples 1 to 4) in which the water resistance of the grease A sealed between the two contact seals 5 and 6 is 0.1 to 2.0%, and the water resistance of the grease A to water washing A sealed type rolling bearing (comparative example) with 3.7% was prepared. The sealed rolling bearings of each of these examples and comparative examples were attached to a rotating test machine in an environment where muddy water was scattered, and a moisture penetration test was conducted to investigate the presence or absence of moisture penetration into the bearing space. In addition to the presence or absence of moisture intrusion, the state of the sealed grease A after the test was also observed. The test conditions are as follows.
・ Rotation speed: 1000rpm
・ Test time: 160 hours

  The results of the moisture penetration test are shown in Table 1. Examples 1 to 3 in which the grease A has a water resistance of 0.1 to 1.5% in water are not infiltrated into the bearing space at all, and the water resistance of water to be cleaned is 2.0% in Example 4 As for the thing, infiltration of the water | moisture content was recognized slightly. On the other hand, in the comparative example having a water resistance of 3.7% for washing, the grease A flowed out after the test, and a clear water intrusion was observed. Further, none of Examples 1 to 4 caused the grease A to flow out, and Example 1 having a water wash resistance of 0.1% showed no softening of the grease A.

  In the embodiment described above, the sealed type rolling bearing is a ball bearing, but the sealed type rolling bearing according to the present invention can also be used for other types of rolling bearings such as a roller bearing. Further, the form of each of the inner and outer contact seals is not limited to that of the embodiment.

Longitudinal sectional view showing an embodiment of a sealed rolling bearing Sectional drawing which expands and shows the principal part of FIG.

Explanation of symbols

A, B Grease 1 Inner ring 1a Seal sliding contact surface 1b Stepped portion 2 Outer ring 2a Seal sliding contact surface 2b Groove 3 Ball 4 Cage 5, 6 Contact seal 5a, 6a Metal core 5b, 6b Elastic member 5c, 6c Lip

Claims (2)

  In a sealed type rolling bearing in which a bearing space between an inner ring and an outer ring is sealed with a contact seal in which a lip formed of an elastic member is brought into contact with a seal sliding contact surface provided on the inner ring or the outer ring, the bearing space is contacted between two inner and outer rings A sealed type rolling bearing characterized in that it is sealed with a seal, and between these two inner and outer contact seals, grease having a water wash resistance of 2% or less specified in JIS K-2220 is sealed.   The sealed rolling bearing according to claim 1, wherein, of the two inner and outer contact seals, a lip of an outer contact seal is brought into contact with a seal sliding contact surface provided on an inner peripheral surface of the outer ring.

Images