WO2007058243A1

WO2007058243A1 - Grease-enclosed constant velocity universal joint

Info

Publication number: WO2007058243A1
Application number: PCT/JP2006/322831
Authority: WO
Inventors: Mika Kohara
Original assignee: Ntn Corporation
Priority date: 2005-11-18
Filing date: 2006-11-16
Publication date: 2007-05-24

Abstract

This invention provides a constant velocity universal joint that can prevent damage to a boot in a constant velocity joint caused by expansion of the boot or removal of the boot from a boot band through centrifugal force due to the action of the mass of a lubricating oil on the boot and, at the same time, can suppress the movement of a lubricating grease from a sliding part into the boot and can prevent the exhaustion of the lubricating grease in the sliding part in inner and outer rings. A lubricating grease is filled into between an outer ring (2) and an inner ring (1). A bellows-type boot (8) of rubber or resin is mounted so as to lie astride the outer periphery of the outer ring (2) and the outer periphery of a shaft (7) held by the inner ring (1). The boot (8) has on its inside an elastic resin foam (9) filled into and molded integrally with the boot (8). The elastic resin foam (9) has elasticity high enough to follow the bending deformation of the boot (8) and has lower specific gravity than the lubricating grease. The end parts of the boot (8) are fastened with a belt-shaped fastening tool (the so-called boot bands) (10, 11) for hermetical sealing.

Description

Specification

Grease-filled constant velocity universal joint

Technical field

[0001] The present invention is used for, for example, a joint of a rotating shaft of an automobile or other power transmission system, and is equipped with a grease-degraded constant velocity fitted with a bendable deformable boot that seals and protects a joint mechanism that holds grease. It relates to a universal joint.

Background art

[0002] The structure of a general grease-filled constant velocity universal joint will be described with reference to FIG. 1. The outer peripheral surface of the inner ring 1 and the inner peripheral surface of the outer ring 2 have a plurality of, for example, about six extending in the axial direction. Grooves 3 and 4 are formed, and the grooves 3 and 4 are formed on the inner ring 1 and the outer ring 2 so as to face each other. The rolling elements 5 mounted so as to be rotatable by being guided by these pairs of grooves are rotatably held by the cage 6, and thus the crossing angles of the respective axes of the inner ring 1 and the outer ring 2 are determined. When it changes, the angular variation is allowed by the axial movement of the rolling element 5 in the groove set, and even in such a state, the rotational force is transferred from each groove to the inner ring 1 and the outer ring 2 via the rolling element 5. Transmitted between each other.

[0003] Such a constant velocity joint is fitted with a rubber or grease boot 8 so as to straddle the outer periphery of the outer ring 2 and the outer periphery of the shaft 7 held by the inner ring 1. Lubricating grease (not shown) was enclosed in 70% or more of the total volume including the internal space volume of 8.

[0004] By the way, the main part where the lubricant is actually required is a sliding part that is housed inside the outer ring that is not inside the boot, and exists between the inner ring of the outer ring rolling element (ball) cage, If the lubrication grease is held in the sliding part inside the outer ring, the required amount of lubrication oil is supplied. Therefore, as described above, a large amount of lubrication grease of 70% or more including the internal space volume of the boot 8 There is no need to enclose.

[0005] If the constant velocity joint continues to be used with the force applied, even if the lubricating grease is initially sealed in the sliding part between the outer ring and the inner ring, it gradually moves into the boot and requires lubrication. In order to prevent the occurrence of this phenomenon, grease that has been depleted at the critical sliding part has always been used in order to prevent this phenomenon from occurring. [0006] By the way, when a large amount of lubricating grease is sealed in the boot in this way, the amount of lubricating oil required for the sliding portion between the outer ring and the inner ring exceeds the amount of lubricating oil, and the constant velocity joint is used. When rotating at high speed, the boot is stretched or expanded due to the centrifugal force applied to the lubricating grease, the bent part of the boot, the overlapping part of the boot, the boot band fixed to the shaft, It is also expected that the fixed part of the metal will be worn and damaged by rubbing.

[0007] In addition, the lubrication grease force that hardens at low temperatures also weakens the durability of the boot even if it rubs against the boot, so that the boot replacement time is accelerated, and at that time the lubricating grease is filled and the boot replacement work Is complicated.

[0008] In order to deal with such problems, an oil-impregnated foam in which a foamed synthetic resin such as a silicone foam is impregnated with a lubricating oil in advance is prepared, and this is filled in a boot, that is, using lubricating grease. There is also known a constant velocity joint that has a low specific gravity and is made as light as possible in the boot by impregnating a foamed synthetic resin with a lubricating oil (Patent Document 1).

Patent Document 1: Japanese Patent Laid-Open No. 9 42297

Disclosure of the invention

Problems to be solved by the invention

[0010] However, if the foamed synthetic resin is impregnated with the synthetic resin and held in the boot in the above-described prior art, the constant velocity joint is not much different from the case where the lubricating grease is directly filled in the boot. Therefore, a considerable centrifugal force acts on the oil-impregnated foamed synthetic resin in the boot, and the boot expands so that the rubber boot is pushed to the outside of the internal force, and the material of the boot deteriorates due to repeated tension and wear at that time Problem of damage. In addition, the lubricating oil impregnated with the foamed synthetic resin may promote deterioration of the boot material by coming into contact with the boot, and the boot may be cracked.

[0011] In addition, even if the degree of expansion of the boot is relatively small, if the expansion and contraction (return) are repeated by long-term use of the constant velocity universal joint, there is a problem that the boot band is easily loosened.

[0012] Therefore, the problem of the present invention is to solve the above-described problems, and the constant velocity joint boot does not expand due to the centrifugal force acting on the mass of the lubricating oil in the boot and does not come off the boot band. Even if it is indirectly in contact with oil for a long time, it will not be damaged, and the lubricating grease from the sliding part into the boot It is to configure the constant velocity self-joint so that the movement is suppressed and lubrication grease does not dry up in the sliding part of the inner ring and the outer ring.

Means for solving the problem

[0013] In order to solve the above-described problems, in the present invention, lubricating grease is filled between the outer ring and the inner ring of the constant velocity universal joint so as to straddle the outer periphery of the outer ring and the shaft held by the inner ring. A rubber or rosin boot is attached, and the inside of this boot is filled with a foamed elastic sorbent having a specific gravity lower than that of the lubricating grease to prevent the lubricating grease from entering the boot. It was a joint.

[0014] The grease-filled constant velocity universal joint of the present invention configured as described above fills the space between the outer ring and the inner ring of the constant velocity universal joint by filling the inside of the boot with a foamed elastic grease. Lubricating grease force When the boot is bent and deformed, it does not enter the boot, so the lubricant does not disperse and is efficiently supplied concentrated on the required sliding part.

[0015] In addition, the foamed elastic grease inside the boot is adjusted to have a lower specific gravity than the lubricating grease, and in particular, adjusted to a lower specific gravity than the lubricating grease by the amount of bubbles (foaming amount). In use, when centrifugal force is applied, the centrifugal force is smaller than that of conventional oil-impregnated oils containing liquid lubricating oil or lubricating grease. The deformation and wearing of the boot will not occur, and the boot will not be damaged due to so-called rotational expansion.

In addition, a granular foamed elastic resin having an appropriate particle size is filled inside the boot so as not to infiltrate the lubricating grease, so that it is sealed between the outer ring and the inner ring of the constant velocity universal joint. Even when the boot is bent and deformed, the filled lubricating grease hardly penetrates into the inside of the boot, so that the lubricant is efficiently supplied in a concentrated manner on the sliding part where it is necessary.

In addition, the grease-filled constant velocity universal joint of the present invention has no lubricating grease in the boot even when used at a low temperature such as in the severe winter season. The friction between the boot and the boot prevents damage to the boot.

[0017] Further, it is preferable to remove the lubricating grease from the boot as much as possible so that the boot is not damaged by the lubricating grease when starting the constant velocity joint or rotating at a high speed. Therefore, it is preferable to use a grease-filled constant velocity universal joint in which the foamed elastic resin is a non-oil-containing foamed elastic resin foamed in a closed cell state. Further, it is also preferable that the foamed elastic resin is a speedy joint such as a grease-filled elastic resin having a non-oil-containing skin layer on the outermost surface.

[0018] It is preferable that the foamed cocoon resin is a flexible urethane foam. Soft urethane foam can be hardened at room temperature, and the boot will not be damaged by heat.

[0019] In addition, when the boot has a bellows structure, the foamed elastic resin is filled to every corner of the bellows and is integrated with the boot, so that the boot is not deformed so that the bellows are in contact with each other. Boots are hard to damage.

[0020] Further, as a constant velocity universal joint, a plurality of axially extending grooves are provided on the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring so as to face each other, and are rotated so as to be rotatably guided by the pair of grooves. By providing the moving body by holding it in a cage, it is possible to allow fluctuations in the crossing angle between the inner ring and outer ring shafts by the axial movement of the groove of the rolling element, and the rotational force from each groove via the rolling element. Grease-filled constant velocity universal joints that are constant velocity universal joints that transmit to the inner and outer rings can be used.

[0021] The lubricating grease filled in the outer ring acts efficiently on the sliding portion even if the amount is relatively small. Therefore, a plurality of grooves and rolling elements extending in the axial direction on the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring, and sliding portions between the rolling elements and the cage can be reliably lubricated. The invention's effect

[0022] According to the present invention, lubricating grease is filled between the outer ring and the inner ring of the constant velocity universal joint, and the rubber boot is filled with low-specific gravity and elastic foamed elastic resin so as to be integrally molded. Because it is a grease-filled constant velocity universal joint, the boot force of the constant velocity joint does not cause deformation such as expansion due to the centrifugal force acting on the mass of lubricating oil in the boot, making it difficult to come off from the boot band, and excessive lubrication grease There is an advantage that lubricating grease does not easily occur in the sliding portion without entering the inside.

[0023] If the foamed elastic resin is a non-oil-containing foamed elastic resin foamed in a closed cell state, such as a flexible urethane foam, or a foamed elastic resin having a skin layer on the outermost surface, the boot Lubricating oil or the like is less likely to enter the inside, and the above-described effect is further ensured. [0024] When the boot has a bellows structure, the deformation of the boot in which the bellows contact each other is prevented, and the boot is not easily damaged during use.

Furthermore, the constant velocity joint of the specified structure is efficiently lubricated with a small amount of lubricating grease, and the sliding of the inner ring and outer ring groove and the rolling element as the sliding part, and the rolling element and the cage are surely lubricated. There are lj points.

Brief Description of Drawings

[0025] [FIG. 1] A sectional view of the constant velocity universal joint of the first embodiment.

[Fig. 2] Sectional view of constant velocity universal joint of the second embodiment

Explanation of symbols

[0026] 1 Inner ring

2 Outer ring

3, 4 grooves

5 Rolling elements

6 cage

7 axes

8 Boots

9, 9 'Foamed elastic resin

10, 11 Band fastener

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the grease-filled constant velocity universal joint according to the first embodiment is provided with a plurality of axially extending grooves 3 and 4 on the outer peripheral surface of the inner ring 1 and the inner peripheral surface of the outer ring 2 so as to face each other. A ball-shaped rolling element 5 is held by a cage (retainer) 6 so as to be rotatably guided by the pair of grooves 3 and 4, thereby crossing the respective axes of the inner ring 1 and the outer ring 2. With the structure that can transmit the rotational force to each groove 3, 4 force inner ring 1 and outer ring 2 through the rolling element 5. It is.

[0028] The constant velocity joint having such a structure is filled with lubricating grease between the outer ring 2 and the inner ring 1 so that the rubber extends over the outer periphery of the outer ring 2 and the outer periphery of the shaft 7 held by the inner ring 1. Made of sebum or sebum A bellows type boot 8 is installed, and this boot 8 is filled with a flexible elastic foamed elastic resin 9 that can follow the bending deformation of the boot 8 and having a specific gravity lower than that of the lubricating grease. Are integrally molded and fastened with belt-like fasteners (so-called boot bands) 10 and 11 and sealed.

[0029] As shown in FIG. 2, the grease-filled constant velocity universal joint of the second embodiment is different from the structure of the first embodiment in that instead of integrally molding the foamed brittle resin 9 with the boot 8, the boot 8 The inner part of the belt is packed with a granular foamed elastic resin 9 'having a flexible elasticity capable of following the bending deformation of the boot 8 so that a gap for allowing the lubricating grease to enter is as close as possible, and a belt-like fastener (so-called boot band) ) Fastened with 10 and 11 and sealed.

The boot used in the present invention has a rubber or grease material strength, and has a sealing property against dust and water in the atmosphere, tear resistance, oil resistance, heat resistance, wear resistance, etc. For example, chloroprene rubber or thermoplastic polyester elastomer (manufactured by Toray DuPont: Hytrel) can be used. In addition, plasticizers, softeners, lubricants, antioxidants, reinforcing agents and the like may be added.

[0030] The lubricating grease used in the present invention is not particularly limited in its type. For example, base oil is increased with a metal stone-based thickener, and further, such as molybdenum disulfide molybdenum. An example of using an extreme pressure agent added can be given.

[0031] Examples of the base oil include mineral oils, ester-based synthetic oils, ether-based synthetic oils, hydrocarbon-based synthetic oils, and the like, and may be a single component or a mixed component base oil. Of course.

[0032] The foamed elastic resin used in the present invention employs a soft elastic resin having oil resistance and heat resistance. For example, a soft polyurethane resin foam, a silicone resin foam, a polyethylene foam And foams such as polypropylene foam and ethylene acetate butyl copolymer.

[0033] The foamed elastic resin may be a closed-cell foam or an open-cell foam as long as it has a required elastic force, but preferably a closed-cell foam. When a soft open-cell foam is used, it is preferable to form a skin layer that does not have air bubbles on the surface of the molded body in the boot that contacts the outer ring, and to make the lubricant as hard as possible to impregnate. That's right.

The particle size and molding conditions of the granular foamed elastic resin used in the second embodiment are not particularly limited, but the smaller particle size than the large particle size is bent in the bent bellows boot. This is preferable because it can be densely packed. Specifically, a suitable particle size is preferably a substantially spherical or elliptical sphere having a diameter or major axis of 1 to about LOmm. A more preferred diameter or major axis is 1 to 5 mm, further 1 to 3 mm.

[0034] When the polyurethane resin is employed, the raw material mainly composed of isocyanate and the raw material mainly composed of polyol are mixed using a RIM (Reaction Injection Molding) developing machine, etc. The raw material mixture can be injected and cured inside, or it can be formed into a spherical shape or an elliptical spherical shape using a molding machine or the like.

In that case, the amount of bubbles can be adjusted by dissolving at least one gas selected from an inert gas and air in a raw material mainly composed of polyol.

[0036] As the polyol component constituting the liquid polyurethane raw material, well-known polyols such as polyether polyols, polyester polyols, and polymer polyols that are generally used in the production of flexible polyurethane foams can be used. The polyisocyanate component is a known polyisocyanate having at least two or more functional groups such as 2, 4- and 2, 6-tolylene diisocyanate (TDI), orthotoluidine diisocyanate (TODI), Naphthylene diisocyanate (NDI), xylylene diisocyanate (XDI), 4, 4'-diphenylmethane diisocyanate (MDI), and carbodiimide modified MDI, polyethylene polyisocyanate, polymeric polyisocyanate Etc. can be used alone or in combination.

[0037] When silicone resin is employed, for example, silicone foam SEF series manufactured by Toray 'Dowcoung' Silicone Co. can be employed.

Example 1

[0038] 10% by weight of a lithium oil cake using mineral oil as a base oil and 12hydroxystearic acid as a fatty acid as a thickener, and 2% by weight of molybdenum disulfide as an extreme pressure additive, molybdenum Lubricating grease containing 3% by weight of dialkyl dithiocarbamate and 3% by weight of zinc dithiocarbamate was prepared by a conventional method. [0039] The obtained lubricating grease is filled in the gap between the outer ring and the inner ring of the constant velocity universal joint, and a bellows type formed by a thermoplastic polyester elastomer (manufactured by Toray DuPont: Hytrel) on it. I wore boots.

[0040] Next, a metal boot band is fitted and fastened to the large-diameter portion, soft polyurethane foam is filled and foamed from the gap between the inner edge of the small-diameter portion and the shaft, and then the metal boot band is fitted to the small-diameter portion and fastened. Thus, a constant velocity universal joint filled with grease of the form shown in FIG. 1 was obtained.

[0041] A durability test was conducted when the obtained constant velocity universal joint was rotated at a predetermined operating angle under a predetermined load and rotated at room temperature for 650 hours.

[0042] As a result, the external appearance was observed immediately after the rotation for 650 hours, the inside of the boot was cut and observed as necessary, and the sliding portion inside the outer ring of the joint was disassembled and observed. The inner / outer boots and the boots did not show any damage or abnormal wear.

Example 2

[0043] Lubricating grease prepared in exactly the same manner as in Example 1 was filled in the gap between the outer ring and inner ring of the constant velocity universal joint without the shaft.

[0044] On the other hand, a bellows type boot made of thermoplastic polyester elastomer (manufactured by Toray DuPont: Hytrel) is attached to the outer periphery of the shaft that can be attached to the inner ring of the constant velocity universal joint, A metal boot band was fitted to the small diameter part of the boot and fastened tightly to the outer periphery of the shaft.

Next, the opening of the large-diameter portion of the boot faces upward, and this opening force is filled with foamed polyurethane foam by filling the boot with a large-diameter portion edge and filling the inside. A shaft with boots filled with polyurethane foam was made.

Next, the shaft with the boot is inserted into the inner ring of the constant velocity universal joint without the shaft, and the large diameter portion of the boot is fitted on the outer periphery of the outer ring and fastened with a metal boot band for sealing. A grease-filled constant velocity universal joint with the configuration shown in Fig. 1 was manufactured.

Example 3

[0047] Lithium sarcophagus containing mineral oil as a base oil and 12 hydroxystearic acid as a fatty acid is added as a thickening agent in an amount of 10% by weight, and as an extreme pressure additive, 2% by weight of molybdenum disulfide and molybdenum. 3% by weight of dialkyl dithiocarbamate and zinc dithiocarbamate Lubricating grease containing 3% by weight was prepared by a conventional method.

[0048] The obtained lubricating grease is filled in the gap between the outer ring and the inner ring of the constant velocity universal joint, and a bellows type formed by a thermoplastic polyester elastomer (manufactured by Toray DuPont: Hytrel) on it. I wore boots.

[0049] Next, a metal boot band is fitted and fastened to the large diameter portion, and a 2mm diameter spherical granular foamed elastic resin having a soft polyurethane foam force is formed from the gap between the inner edge of the small diameter portion and the shaft. Then, a metal bracelet was fitted into the small diameter portion and fastened to obtain a grease-filled constant velocity universal joint as shown in FIG.

[0050] A durability test was conducted when the obtained constant velocity universal joint was rotated at a predetermined operating angle under a predetermined load and rotated at room temperature for 650 hours.

[0051] As a result, when the appearance, the inside of the boot (cut and observed as necessary) and the sliding part inside the outer ring of the joint were disassembled and observed immediately after the rotation for 650 hours, In addition, the boots did not show any damage or abnormal wear.

Example 4

[0052] Lubricating grease prepared in exactly the same manner as in Example 3 was filled in the gap between the outer ring and inner ring of the constant velocity universal joint without the shaft.

[0053] On the other hand, a bellows type boot formed of a thermoplastic polyester elastomer (manufactured by Toray DuPont: Hytrel) is attached to the outer periphery of a shaft that can be attached to the inner ring of the constant velocity universal joint. A metal boot band was fitted to the small diameter part of the boot and fastened tightly to the outer periphery of the shaft.

[0054] Next, the opening of the large-diameter portion of the boot is directed upward, and the opening force of the spherical soft polyurethane foam (used in Example 3 so as to leave the large-diameter portion edge and fill the inside of the boot) The shaft with the boots filled with soft polyurethane foam particles was prepared.

[0055] Next, the shaft with the boot is inserted into the inner ring of the constant velocity universal joint without the shaft, and the large diameter portion of the boot is fitted on the outer ring outer periphery and fastened with a metal boot band to be sealed. A constant velocity universal joint filled with grease of the form shown in Fig. 2 was manufactured.

[0056] The obtained constant velocity universal joint was loaded with a constant load at a predetermined operating angle and at room temperature for 650 hours. The durability test of rotating was performed, and the appearance immediately after the test, the inside of the boot (cut and observed if necessary) and the sliding part inside the outer ring of the joint were disassembled and observed. The inner / outer boots and the boots were not damaged or abnormally worn.

Claims

The scope of the claims

[1] Lubricating grease is filled between the outer ring and the inner ring of the constant velocity universal joint, and a rubber or grease boot is mounted so as to straddle the outer circumference of the outer ring and the outer circumference of the shaft held by the inner ring. A grease-filled constant velocity universal joint that is filled with foamed elastic resin having a specific gravity lower than that of the lubricating grease to prevent the lubricating grease from entering the boot.

[2] The grease-filled constant velocity universal joint according to claim 1, wherein the foamed elastic resin is a foamed elastic resin having elasticity capable of following the bending deformation of the boot.

[3] The grease-filled constant velocity universal joint according to claim 1 or 2, wherein the foamed elastic resin is a granular foamed elastic resin.

[4] The grease-filled constant velocity universal joint according to any one of claims 1 to 3, wherein the foamed elastic resin is a closed-cell foamed elastic resin.

[5] The grease-sealed constant velocity universal joint according to any one of claims 1 to 3, wherein the foamed cocoon resin is a flexible urethane foam.

[6] The grease-filled constant velocity self-joint according to any one of claims 1 to 3, wherein the boot has a bellows structure.

[7] The constant velocity universal joint is provided with a plurality of axially extending grooves on the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring, and the rolling element is caged so as to be rotatably guided by the pair of grooves. By holding the inner ring and the outer ring, the variation in the crossing angle between the shafts of the inner ring and the outer ring is permitted by the axial movement of the groove of the rolling element, and the rotational force is transferred from each groove through the rolling element. The grease-filled constant-velocity white joint according to any one of claims 1 to 3, wherein the constant-velocity universal joint transmits to the outer ring.