Patent Publication Number: US-2019178299-A1

Title: Constant velocity joint with vent sleeve

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/595,838, filed on Dec. 7, 2017. The entire disclosure of the above application is hereby incorporated herein by reference. 
    
    
     FIELD 
     The present invention relates to joint assemblies and more particularly to an assembly for venting elevated pressure within the joint assemblies. 
     BACKGROUND OF THE INVENTION 
     Joint assemblies such as constant velocity joints are common components in automotive vehicles for applications requiring a transmission of rotating motion such as constant velocity motion. Constant velocity joints (CV joints) are typically used to transmit torque from a transmission of a vehicle to final drive components at a constant velocity or speed. 
     Common types of CV joints include an outer joint member and an inner joint member. The outer joint member typically includes a hollow chamber which is open at one end and closed at an opposing end. The inner joint member is configured to receive a shaft of the vehicle and includes roller assemblies coupled thereto. The outer joint member co-axially receives the inner joint member. A boot is typically employed for sealing the CV joint from outside contaminants such as water, dirt, and other environmental components which can cause damage to the CV joint. Generally, the boot is coupled adjacent to an open end of the outer joint member, covers the inner joint member received in the chamber, and engages the shaft to seal the chamber. 
     However, during operation of the vehicle, especially during operation at high temperatures, high internal pressure can build up within the chamber of the CV joint. The high internal pressure may cause the boot to deform or expand in a manner that can be detrimental to the durability, sealing, or function of the boot, thus minimizing the effectiveness and longevity of the CV joint. Therefore, it is desired to vent the pressures contained or built up within the chamber of the CV joint to the atmosphere. 
     Prior art vent channels used to vent the CV joint are complex and difficult to manufacture. For example, some CV joints utilize a complex combination of axially, circumferentially, or helically oriented and continuous vent channels formed along an inside surface of the boot. An example of these complex combinations of vent channels are shown and described in U.S. Pat. No. 6,793,584, the disclosure of which is hereby incorporated herein in its entirety. These complex combinations of channels are not only difficult to manufacture but are prone to deformation as a result of thin cross-sections created by the vent channels. The thin cross-sections are typically formed at an area of the boot subject to high compression and deformation from an external retention clamp. The retention clamp is typically employed to engage the boot to the shaft of the inner joint member. The compression and deformation may cause the vent channels to become blocked. 
     Another prior art system used to vent CV joints relies on axial grooves on the inner surface of the boot as shown and described in U.S. Pat. No. 9,206,858, the disclosure of which is hereby incorporated herein in its entirety. The axial grooves cooperate with a circumferential groove formed on an inner boot sleeve located in contact with the inner joint member, and disposed between the boot and the shaft of the inner joint member, to form a continuous vent path. This system minimizes a complexity of the configuration of the vent paths and increases rigidity of a vent path less prone to deformation in the area of the boot adjacent the external retention clamp. 
     Additionally, as mentioned hereinabove, CV joint venting is commonly attained through use of vent channels defined by grooves formed on the inner surface of the boot or boot sleeve cooperating with the outer surface of the shaft. The shaft and boot sleeve are commonly formed from a steel material or a similar metal. Therefore, a surface of the vent channels contain steel (or similar material) surfaces when grooves of the boot or sleeve form a vent channel against the outer diameter of the shaft. As a result, the vent channels are prone to corrosion at the steel surfaces when water becomes trapped within the vent channels. The corrosion from the water can cause the steel surface to scale or blister. In turn, the vent channels can become blocked. An example of a boot sleeve with an inner helical groove cooperating with the shaft is shown and described in U.S. Pat. No. 4,224,808, the disclosure of which is hereby incorporated in its entirety herein. Additional disadvantages of the aforementioned boot sleeve are the relatively lengthy helical/spiral groove formed in the inner diameter of the sleeve which increases complexity of manufacturing and assembly. 
     A similar corrosion concern exists for CV joints having an outer pressure-activated diaphragm seal. The diaphragm seal is usually formed at an axial end of the boot and rests on the shaft or sleeve. The steel surface of the shaft or sleeve can cause the diaphragm seal to wear or corrode. 
     Accordingly, it would be desirable to provide a CV joint that maximizes venting efficiency of internal pressure contained therein and minimizes corrosion and deformation of components thereof. 
     SUMMARY OF THE INVENTION 
     In accordance and attuned with the present invention, provide a CV joint that maximizes venting efficiency of internal pressure contained therein and minimizes corrosion of components thereof, has surprisingly been discovered. 
     According to an embodiment of the disclosure, a constant velocity joint includes a shaft. The constant velocity joint also includes a boot member. The boot member covers a portion of the shaft. A corrosion resistant sleeve is disposed intermediate the shaft and the boot member. The sleeve includes a vent channel. The vent channel is formed only in an outer surface of the shaft. 
     According to another embodiment of the disclosure, a constant velocity joint includes a shaft extending from an inner race of the constant velocity joint and a boot member covering a portion of the shaft. A corrosion resistant sleeve is disposed intermediate the shaft and the boot member. A vent channel is formed only in the sleeve. 
     According to yet another embodiment of the disclosure, a constant velocity joint is disclosed. The constant velocity joint includes a shaft extending from an inner race of the constant velocity joint and a boot member covering a portion of the shaft and the inner race. The boot member has a first end and a second end. The boot member defines a first inner region adjacent the first end thereof. A corrosion resistant sleeve is disposed intermediate the shaft and the boot member. A vent channel is formed helically in an outer surface of the sleeve. The vent channel provides fluid communication between the first inner region and a second inner region disposed adjacent the second end of the boot member or the environment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above advantages of the invention will become readily apparent to those skilled in the art from reading the following detailed description of an embodiment of the invention in the light of the accompanying drawing which is a top perspective view of a portion of a joint and shaft assembly according to an embodiment of the disclosure. 
         FIG. 1  illustrates a fragmentary cross-sectional front elevational view of an inner race, a shaft, a sleeve, and a boot assembly of a constant velocity joint according to an embodiment of the disclosure; 
         FIG. 2  illustrates a front perspective view of the sleeve of the constant velocity joint of  FIG. 1 ; and 
         FIG. 3  illustrates a cross-sectional front elevational view of a sleeve of a constant velocity joint according to another embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following detailed description and appended drawings describe and illustrate various exemplary embodiments of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner. In respect of the methods disclosed, the steps presented are exemplary in nature, and thus, the order of the steps is not necessary or critical. 
     As used herein, substantially is defined as “to a considerable degree” or “proximate” or as otherwise understood by one ordinarily skilled in the art. Except where otherwise expressly indicated, all numerical quantities in this description are to be understood as modified by the word “about” and all geometric and spatial descriptors are to be understood as modified by the word “substantially” in describing the broadest scope of the technology. “About” when applied to numerical values indicates that the calculation or the measurement allows some slight imprecision in the value (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If, for some reason, the imprecision provided by “about” and/or “substantially” is not otherwise understood in the art with this ordinary meaning, then “about” and/or “substantially” as used herein indicates at least variations that may arise from ordinary methods of measuring or using such parameters. Where any conflict or ambiguity may exist between a document incorporated by reference and this detailed description, the present detailed description controls. Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, or layer. 
     The present technology relates to joint and shaft assemblies, such as constant velocity joints and shafts, used in vehicles. However, the present disclosure can apply to other types of joint and shaft assemblies used in vehicles or in other applications. Joint and shaft assemblies according to the disclosure are configured to facilitate a transmission of rotational forces and torque between components of a vehicle. 
       FIGS. 1-2  illustrate a constant velocity (CV) joint  10  according to the disclosure. The joint  10  can be a tri-pod type or ball-type constant velocity joint. Additionally, the joint  10  can be a plunging or fixed constant velocity joint. The joint  10  includes an inner race  12 , an outer race (not shown), and a boot assembly  16 . The outer race is configured to receive a shaft extending from one end thereof. The inner race  12  is coupled to a shaft  24  such as a drive shaft or propeller shaft, for example, and is received in the outer race. 
     A plurality of rolling elements (not shown) is disposed intermediate an outer surface of the inner race  12  and an inner wall of the outer race. The rotation of the outer race will rotate the inner race  12  at substantially the same or constant speed. As a result, a constant velocity will flow through the joint  10  between two shafts such as the shaft of the outer race and the shaft  24  of the inner race  12 . The rolling elements permit the shaft  24  of the inner race  12  and the shaft of the outer race to be angled with respect to each other. 
     The boot assembly  16  is formed from two main components: a boot member  18  and a boot cover  19 . The boot cover  19  engages an outer surface of the outer race at one end and engages the boot member  18  at an opposing end. For example, the boot cover  19  includes a channel formed along an entire periphery of the opposing end to receive a first end  20  of the boot member  18 . The boot member  18  is typically formed from a urethane or other rubber material. However, it is understood, the boot member  18  can be formed from any other type of plastic, rubber, or other known pliable or flexible material, as desired. A second end  22  of the boot member  18  engages a sleeve  26  received on the shaft  24 . According to another embodiment (not shown), the boot member  18  and the boot cover  19  can be integrally formed to form a unitary boot assembly  16 . 
     The boot assembly  16  is configured to seal the joint  10  from any outside contaminants such as water, dirt, environmental particulates, and other undesired materials. The boot member  18  illustrated is typical of a “J-boot” style seal, a diaphragm seal, or bellow seal. However, the boot member  18  according to the instant disclosure is not limited to the aforementioned styles of seals. The instant disclosure can be applied to boot members  18  and boot assemblies  16  of other types such as boot assemblies having boot members with multiple convolutes and commonly formed from thermoplastic elastomers. 
     The boot member  18  includes a diaphragm  36  formed adjacent the second end  22  thereof. The diaphragm  36  is pressure-activated and expands to permit undesired high-temperature and/or high-pressure gases formed within the boot assembly  16  to escape from the boot assembly  16 . The diaphragm  36  is also a one-way sealing diaphragm to militate against the ingress of water and/or contaminants into the joint  10  while still permitting the egress of the undesired high temperature and high pressure gases. 
     The boot member  18  is generally bell-shaped in cross-section including a first portion  18   a  angling outwardly from the sleeve  26  and the shaft  24  and extending from the boot cover  19  to a second portion  18   b  of the boot member  18 . The second portion  18   b  of the boot member  18  engages the sleeve  26  to form a seal therewith. A third portion  18   b  includes the diaphragm  36  adjacent the second end  22  thereof which selectively engages the sleeve  26  and expands outwardly from the sleeve  26  to release gases from the boot assembly  16 . 
     The sleeve  26  is typically formed from a corrosion resistant material. For example, the sleeve  26  can be formed from a non-metallic material such as a thermoset material, a thermoplastic material, an elastomeric material, or a polymeric material. In another example, the sleeve can be formed from a metallic material treated with anti-corrosion coatings. The sleeve  26  is disposed directly intermediate the boot member  18  and the shaft  24 . The sleeve  26  extends from minimally beyond the second end  22  of the boot member  18  inwardly towards the first end  20  of the boot member  18 . However, the sleeve  26  does not extend to the inner race  12 , wherein the a first end  28  of the sleeve  26  extends slightly beyond the second end  22  of the boot member  18  and a second end  30  of the sleeve  26  is disposed intermediate the second end  22  of the boot member  18  and the second portion  18   b  of the boot member  18 . The sleeve  26  may be secured and sealed to the shaft  24  through a variety of means such as an interference fit, an adhesive, a press-fit, a locking ring, or other securing or attachment means or combinations thereof. 
     A vent channel  32  is formed in an outer surface  34  of the sleeve  26 . The vent channel  32  cooperates with the boot member  18  to form passages for venting high temperature and high pressure gases from the boot assembly  16 . The passage formed by the vent channel  32  cooperating with the boot member  18  permits fluid communication between a first inner region  38  defined by the first portion  18   a  of the boot member  18  covering the inner race  12  and a second inner region  40  formed beneath the diaphragm  36 . In the embodiment illustrated, the vent channel  32  is helical. However, in other embodiments, the vent channel  32  may include one or more helical channels, axial channels, circumferential channels, or channels having other shapes or configurations or combinations thereof. 
     In the embodiment illustrated in  FIGS. 1-2 , the vent channel  32  is formed only in the outer surface  34  of the sleeve  26 , wherein grooves, vent paths, or channels are not formed in the boot member  18  or the shaft  24  to cooperate with the vent channel  32 . As a result, the vent channel  32  is simple while providing efficient venting between the first inner region  38  and the second inner region  40 . However, according to a first alternate embodiment, the passage formed by the vent channel  32  can be formed between the shaft  24  and the sleeve  26 . For example, as shown in  FIG. 3 , the vent channel  32  can be formed in an inner surface  35  of the sleeve  26 . However, in other embodiments (not shown), the vent channel  32  can be formed in an outer surface of the shaft  24  or a combination of both the shaft  24  and the sleeve  26 . According to another embodiment, the passage formed by the vent channel  32  can be formed between the sleeve  26  and the boot member  18  such as formed within the boot member  18 . According to a yet another alternate embodiment, the passage can be any combination of the vent channel  32  formed in the outer surface of the shaft  24 , the inner surface  35  of the sleeve  26 , the outer surface  34  of the sleeve  26 , and the inner surface of the boot member  18 . 
     The sleeve  26  may be molded separately from the shaft  24  and received thereon or may be molded in place about the shaft  26 . The sleeve  26  is annular and cylindrical. However, the sleeve  26  may be semi-cylindrical or partially cylindrical having a C-shaped cross-section, wherein a gap formed between arcuate ends of the sleeve  26  forms a portion of or an addition to the vent channel  32 . 
     In the embodiment shown in  FIG. 1 , the diaphragm  36  directly contacts the sleeve  26  and does not contact the shaft  24 . However, in other embodiments, the boot member  18  does not include the diaphragm  36 . According to the embodiment without the diaphragm  36 , the second inner region  40  is not included and the passages formed by the vent channels  32  provide fluid communication between the first inner region  38  and the atmosphere. 
     Advantageously, the CV joint  10  according to the present disclosure militates against corrosion of metal components of the joint  10  which facilitates an extended life of the CV joint  10  and minimizes deformation of the boot member  18 . As a result, maximized efficiency of the boot assembly  16  is maintained. Additionally, one continuous path is formed by the vent channel  32 . In the embodiment where the vent channel  32  is formed on the inner surface of the sleeve  26 , corrosion is minimized due to the relatively shorter vent channel  32  compared to grooves of prior art. 
     From the foregoing description, one ordinarily skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications to the invention to adapt it to various usages and conditions.