Patent Publication Number: US-2020284325-A1

Title: Sealed tensioner with cartridge body

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Patent Application No. 62/814,926 filed on Mar. 7, 2019, the disclosure of which is herein incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present application relates generally to tensioners of belt and chain drive configurations in automotive applications and, more particularly, relates to sealed hydraulic tensioners of belt and chain drive configurations in automotive applications that lack an outside oil supply. 
     BACKGROUND 
     Rotations of camshafts and crankshafts of internal combustion engines in automobiles are typically linked together. Belt drive and chain drive configurations are common ways to carry this out. Sprockets on the camshafts and crankshafts are linked by an endless belt in belt drive configurations, and similarly the sprockets are linked by an endless chain in chain drive configurations. Still, other components in automobiles are linked by belt drive and chain drive configurations such as front end accessory drive components. 
     The belt and chain drive configurations are commonly equipped with tensioners to help keep the belts and chains tight and under the proper tension as they wear and stretch with use. Some tensioners are spring loaded, and some are hydraulically operated. A conventional hydraulically-operated tensioner has an oil supply from an outside source such as the accompanying internal combustion engine. This usually means that the engine and the tensioner have dedicated oil passages communicating with each other. The outside oil supply also works an unwanted parasitic loss on the engine, among other potential drawbacks. 
     SUMMARY 
     In an implementation, a sealed tensioner may include an outer body, a cartridge body, a piston, a check valve, and one or more baffle walls. The outer body has a first bore. The cartridge body is received in the first bore. The cartridge body has a second bore. The piston is carried in the second bore, and is biased to an extended state. The check valve is situated between a low pressure reservoir and a high pressure chamber. The baffle wall(s) are located at the low pressure reservoir. The baffle wall(s) block an air pocket in the low pressure reservoir from entering the high pressure chamber. 
     In another implementation, a sealed tensioner may include an outer body, a cartridge body, a piston, and one or more baffle walls. The outer body has a bore. The bore has an inner wall. The cartridge body is interfitted in the outer body&#39;s bore. The cartridge body has an outer wall. A low pressure reservoir is established in part or more by a confrontation of the bore&#39;s inner wall and the cartridge body&#39;s outer wall. An air pocket resides in the low pressure reservoir. The piston is carried by the cartridge body. A high pressure chamber is established in part or more by an interior of the piston. The baffle wall(s) extend from the cartridge body and form a seal with the bore&#39;s inner wall. The baffle wall(s) are located near an exit of the low pressure reservoir. 
     In yet another implementation, a sealed tensioner may include an outer body, a cartridge body, a piston, a passage, a check valve, a clearance, and one or more baffle wall(s). The outer body has a first bore. The cartridge body is received in the first bore. The cartridge body has a second bore. A low pressure reservoir is established in part or more by confronting walls of the outer body and cartridge body. An air pocket resides in the low pressure reservoir. The piston is carried in the second bore and is biased to an extended state. The piston has an interior. A high pressure chamber is established in part or more by the piston&#39;s interior. The passage is defined in the cartridge body and provides fluid travel between the low pressure reservoir and high pressure chamber. The check valve is located at an entrance to the high pressure chamber. The clearance resides between the cartridge body and piston. The baffle wall(s) extend from the cartridge body and are located downstream of an entrance of the high pressure chamber. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an embodiment of a sealed tensioner; 
         FIG. 2  is a sectional view of the sealed tensioner, depicting the sealed tensioner in an extended state; 
         FIG. 3  is another sectional view of the sealed tensioner, depicting the sealed tensioner in a retracted state; 
         FIG. 3A  is an enlarged view of the sealed tensioner taken at the circle denoted by  3 A in  FIG. 3 ; 
         FIG. 4  is a side view of an embodiment of a cartridge body of the sealed tensioner, showing the cartridge body in an upright orientation according to an intended installation position; 
         FIG. 5  is a side view of the cartridge body, showing the cartridge body in a tilted orientation; and 
         FIG. 6  is a side view of the cartridge body, showing the cartridge body in an upside-down orientation. 
     
    
    
     DETAILED DESCRIPTION 
     The figures illustrate an embodiment of a sealed tensioner  10  that can be equipped in belt drive and chain drive configurations in automotive applications to help maintain the proper tightness and tension in the associated belts and chains as they wear and stretch with use. The sealed tensioner  10  is hydraulic, and is sealed in the sense that it lacks an outside source of oil supply and hence—unlike some past tensioners—a parasitic loss on the associated larger application is absent with use of the sealed tensioner  10 . The outside source of oil supply is commonly from an internal combustion engine in automotive applications. Since the sealed tensioner  10  has no outside oil supply and hence need not be paired with outside oil passages, the sealed tensioner  10  has a greater degree of freedom for its mounting location in the larger application than previously possible. The sealed tensioner  10  can have various designs and constructions in different embodiments, its precise design and construction oftentimes dictated by the particular application in which it will be employed. In the embodiment presented by the figures, and turning now to  FIGS. 1-3 , the sealed tensioner  10  includes an outer body  12 , a cartridge body  14 , a piston  16 , and a check valve  18 . Still, in other embodiments the sealed tensioner  10  can have more, less, and/or different components than those shown in the figures and described below. 
     With particular reference to  FIG. 1 , the outer body  12  serves as the main exterior structure of the sealed tensioner  10 . The outer body  12  can be attached to a larger application component like an internal combustion engine in installation, and in this regard has a pair of mounting bosses  20  to effect attachment in this embodiment. A pair of tabs  22  receive a shipping pin  24  that keeps the piston  16  in place while the sealed tensioner  10  is being handled and in transit prior to installation to the larger application component. Once installed, the shipping pin  24  can be removed. Turning now to  FIG. 2 , the outer body  12  has a bore  26  at its interior. The bore  26  spans through the outer body  12  between a first open end  28  and a second open end  30 . The bore  26  has a constant diameter throughout its axial extent. An inner wall  32  of the outer body  12  defines the bore  26 . Unlike the cartridge body  14 , the outer body  12  lacks passages for oil flow in the sealed tensioner  10 . The outer body  12  is a separate and distinct component from the cartridge body  14 , and is hence discretely manufactured. The outer body  12  can be made of a metal material such as steel or aluminum. Because the outer body  12  is separately made, it can be more readily designed and constructed according to a particular installation and its mounting needs, while maintaining the design and construction of the cartridge body  14  and other components of the sealed tensioner  10  if so desired. 
     Turning now to  FIGS. 2 and 3 , the cartridge body  14  is inserted and received in the bore  26  of the outer body  12 . The cartridge body  14  serves to support and assist in establishing other components of the sealed tensioner  10 . The cartridge body  14  is fixed in receipt in the bore  26  of the outer body  12  by way of an interfit therebetween. The interfit can be effected by an interference fit, a shrink fit, or some other technique. The interfit can establish certain sealing interfaces between the outer body  12  and cartridge body  14 , as described below. The structure of the cartridge body  14  can be composed of a metal material such as steel or aluminum and can be fabricated by a casting process in an example; still, the cartridge body  14  could be composed of a plastic material and by an injection molding process, although in this example a bore for the piston  16  may be made with a metal insert and overmolded with the plastic material. A bore  34  of the cartridge body  14  receives and carries the piston  16 . Furthermore, a seal assembly  36  is disposed in the cartridge body  14  and seals fluid  38  within the cartridge body  14  at its location. The fluid  38  can be oil. The seal assembly  36  in this embodiment includes a retaining ring  40 , a seal retainer  42 , an o-ring  44 , and a rod seal  46 . The retaining ring  40  keeps the seal retainer  42  in place, while the seal retainer  42  keeps the o-ring  44  and rod seal  46  in place. In other examples of the seal assembly  36 , the o-ring  44  and rod seal  46  could be kept in place by a groove in the wall of the bore  34 , and the retaining ring  40  and seal retainer  42  could then be absent. 
     Still referring to  FIGS. 2 and 3 , in this embodiment a low pressure reservoir  48  is established near an exterior of the cartridge body  14 , and is defined by confronting walls and surfaces of the outer body  12  and the cartridge body  14 . At a partial circumferential extent of the cartridge body  14 , the inner wall  32  of the bore  26  directly confronts and opposes an outer wall  50  of the low pressure reservoir  48  across a spacing therebetween. The low pressure reservoir  48  holds the fluid  38  at a lower pressure in the sealed tensioner  10 . When the outer body  12  and cartridge body  14  are interfit together as demonstrated in  FIGS. 2 and 3 , a seal  52  is formed around a periphery of the low pressure reservoir  48  to keep the fluid  38  therein. The seal  52  can span around the entire periphery of the low pressure reservoir  48 . A surface-to-surface interface between the inner wall  32  and outer wall  50  at the periphery forms the seal  52 . Although  FIGS. 2 and 3  only depict the upper and lower sections of the periphery of the low pressure reservoir  48  and the seal  52  thereat, the periphery has side sections extending between these upper and lower sections. The seal  52  spans along the side sections. 
     Furthermore, in this embodiment an air pocket  54  resides in the low pressure reservoir  48 . The air pocket  54  accommodates and compensates for decreases in volume that arise in the sealed tensioner  10  when the piston  16  moves toward a retracted state. In this way, the air pocket  54  precludes the occurrence of a hydraulic lock condition in the sealed tensioner  10 . The volume of a high pressure chamber  56  decreases and the amount of the fluid  38  in the low pressure reservoir  48  correspondingly increases as the piston  16  retracts inward in the cartridge body  14 . The fluid  38  is incompressible and hence cannot itself accommodate the volume decreases in the sealed tensioner  10 . Rather, the air pocket  54  compresses in size and presents additional volume availability for the fluid  38  in the low pressure reservoir  48 . The air pocket  54  has an uncompressed state ( FIG. 2 ) when the piston  16  is in an extended state and when no volume compensation is called for in the sealed tensioner  10 , and the air pocket  54  has a compressed state ( FIG. 3 ) when the piston  16  is in the retracted state and when volume compensation is called for in the sealed tensioner  10 . 
     If gas of the air pocket  54  from the low pressure reservoir  48  inadvertently makes its way to the high pressure chamber  56 , it is thought, the functionality of the sealed tensioner  10  could be hampered. Entrance of the gas into the high pressure chamber  56  poses perhaps an increased risk amid shipping and handling, and before installation of the sealed tensioner  10  and when the sealed tensioner  10  could be oriented in a non-installation position. Still, the air pocket  54  could enter the high pressure chamber  56  post-installation and amid operation in certain applications. To preclude the air pocket  54  from entering into the high pressure chamber  56 , one or more baffle walls  58  can be located downstream of an entrance  60  of the high pressure chamber  56 . The precise design and construction and arrangement of the baffle wall(s)  58  can vary in different embodiments and can be dictated by, among other possible influences, the configuration of the low pressure reservoir  48  and that of the high pressure chamber  56 , as well as the intended installation orientation of the sealed tensioner  10  on the larger application component. 
     In the embodiment presented by the figures, and referring now to  FIGS. 4-6 , the baffle wall(s)  58  include a first baffle wall  62 , a second baffle wall  64 , and a third baffle wall  66 . The baffle walls  62 ,  64 ,  66  are unitary extensions of the cartridge body  14  and depend from the outer wall  50  of the cartridge body  14 , and can be structures die cast or machined or formed some other way into the cartridge body  14 . As demonstrated best in  FIGS. 2 and 3 , each of the first and second and third baffle walls  62 ,  64 ,  66  extends fully across the low pressure reservoir  48  and forms a seal  68  at a surface-to-surface interface between the inner wall  32  and a terminal end  70  ( FIG. 4 ) of the respective baffle wall. In this embodiment, and referring to  FIG. 4 , the first and second and third baffle walls  62 ,  64 ,  66  are arranged relative to one another and with respect to an exit  72  of the low pressure reservoir  48  in order to establish an indirect path to the exit  72 . The indirect path is denoted in  FIG. 4  by an arrowed line  74 . Since the air pocket  54  sits atop the fluid  38 , the arrangement of the baffle walls  62 ,  64 ,  66  and the indirect path  74  presents a barrier to the exit  72  for the air pocket  54 , and effectively blocks the air pocket  54  from making its way to the exit  72  and ultimately from making its way to the high pressure chamber  56 . The baffle walls  62 ,  64 ,  66  do not preclude the fluid  38  from entering and exiting the low pressure reservoir  48 , as the fluid  38  can itself follow the indirect path  74 . 
     In this embodiment, the first baffle wall  62  has a downward V-shape and is positioned a short distance above the exit  72 , per the orientation presented in  FIG. 4 . The first baffle wall  62  is spaced from sides of the low pressure reservoir  48  for fluid flow thereby. The second baffle wall  64  is planar and is slanted from a corner of the low pressure reservoir  48  and positioned to one side of the exit  72 . Similarly, the third baffle wall  66  is planar and is slanted from an opposite corner of the low pressure reservoir  48  and positioned to an opposite side of the exit  72 . The second and third baffle walls  64 ,  66  are angled toward each other but maintain a gap therebetween at their terminations. Spacings between the first and second and third baffle walls  62 ,  64 ,  66  establish the indirect path  74 . 
     The arrangement of the baffle walls  62 ,  64 ,  66  is but a single example meant to preclude the air pocket  54  from entering the high pressure chamber  56  for a sealed tensioner that is to be installed in an upright orientation. The upright orientation of the sealed tensioner  10  is shown in  FIGS. 2-4 . Still, the arrangement of baffle walls, as well as the quantity of baffle walls, can vary in other examples for sealed tensioners installed upright and for sealed tensioners intended to be installed in other orientations such as tilted and upside-down orientations presented respectively by  FIGS. 5 and 6 . As an example lacking depiction, for instance, the sealed tensioner  10  could have a single baffle wall located around a large part of the exit&#39;s perimeter to block gas, or the sealed tensioner  10  could have a pair of baffle walls located near the exit&#39;s perimeter to block gas. In the embodiment of the figures, when the sealed tensioner  10  is brought to a tilted orientation like that of  FIG. 5 , the air pocket  54  is blocked from access and entrance to the exit  72  by the first and third baffle walls  62 ,  66 . Further, when the sealed tensioner  10  is brought to an upside-down orientation like that of  FIG. 6 , the air pocket  54  is again blocked from access and entrance to the exit  72  by the first and third baffle walls  62 ,  66 . 
     The piston  16  is urged to press against a component of the larger tensioner assembly such as an arm which itself is pressed against the belt or chain of the particular configuration. The piston  16  is slidably carried in the bore  34  and can reciprocate inward and outward therein in use between the extended state ( FIG. 2 ) and the retracted state ( FIG. 3 ), as well as increments therebetween. The piston  16  is spring loaded and is biased toward the extended state by way of a spring  76 . At an exposed end, the piston  16  has a closed end  78 , and at an opposite end the piston  16  has an open end  80 . The closed end  78  remains projected out of the cartridge body  14  for abutment with the arm in installation and use. The piston  16  defines a hollow interior  82  spanning between the closed end  78  and the open end  80 . A portion of the fluid  38  is present and contained in the interior  82 . 
     The check valve  18  controls flow of the fluid  38  in the sealed tensioner  10  as the piston  16  moves between the extended state and the retracted state, and as the piston  16  moves to incremental states therebetween. The check valve  18  serves as a separation between the low pressure reservoir  48  and the high pressure chamber  56  of the sealed tensioner  10 . The fluid  38  in the low pressure reservoir  48  travels to the high pressure chamber  56  when the piston  16  is in the midst of moving toward the extended state. Conversely, the fluid  38  contained in the high pressure chamber  56  is pressurized to a higher pressure as the piston  16  moves toward the retracted state. The check valve  18  is of the one-way valve type and is spring loaded and biased against fluid-flow from the high pressure chamber  56  to the low pressure reservoir  48 . The check valve  18  has a body  84 , a spring (not shown), and a moveable ball  86 . The moveable ball  86  is biased to a seated and closed position by the spring, as shown by  FIG. 3 .  FIG. 2  shows the moveable ball  86  unseated and in its open position. The check valve  18  opens to permit flow of the fluid  38  from the low pressure reservoir  48  to the high pressure chamber  56  when the piston  16  moves toward the extended state. The check valve  18 , on the other hand, remains closed to prevent flow of the fluid  38  from the high pressure chamber  56  to the low pressure reservoir  48  when the piston  16  moves toward the retracted state. The check valve  18  is located within the piston&#39;s interior  82  and at the open end  80 . In other embodiments the check valve  18  could be a disc check valve or some other type. 
     Turning now to the enlarged view of  FIG. 3A , a clearance  88  is incorporated into the design and construction of the cartridge body  14  and piston  16  in order to furnish a damping effect therebetween as the fluid  38  is forced to travel therethrough. The clearance  88  serves as a purposefully designed fluid leak path between the cartridge body  14  and piston  16 . The clearance  88  can have a dimension that ranges approximately between 0.025-0.065 millimeters (mm); still, other values are possible for this dimension. If greater purposeful leakage is desired in the sealed tension  10 , for instance, metered flow orifices can be lasered into the body  84  of the check valve  18 , as but one example for achieving this. The clearance  88  resides at a surface-to-surface confrontation between the cartridge body  14  and piston  16 , and is defined between an inner surface  90  of the bore  34  and an outer surface  92  of the piston&#39;s wall. The clearance  88  can span around the entire circumferential extent of confrontation between the cartridge body  14  and piston  16 . Similarly, the clearance  88  can span the entire longitudinal extent of confrontation between the cartridge body  14  and piston  16 . By way of the clearance  88 , the fluid  38  can travel from the high pressure chamber  56  to the low pressure reservoir  48  along a return passage  94 . And conversely, the fluid  38  can travel from the low pressure reservoir  48  to the high pressure chamber  56  along a supply passage  96 . A ball plug  98  seals the passages  94 ,  96 . 
     When the sealed tensioner  10  is put in use and the piston  16  is moving to the extended state, the check valve  18  opens to permit flow of the fluid  38  from the low pressure reservoir  48  to the high pressure chamber  56 . The amount of the fluid  38  in the low pressure reservoir  48  is reduced as a result, and the air pocket  54  grows in size to its uncompressed state. Conversely, when the piston  16  is moving to the retracted state the check valve  18  closes to prevent flow of the fluid  38  from the high pressure chamber  56  to the low pressure reservoir  48  via the check valve  18 . The fluid  38  in the high pressure chamber  56  is pressurized and forced to travel through the clearance  88  and to the low pressure reservoir  48 . An arrowed line  100  in  FIG. 3A  demonstrates this forced fluid flow. The forced fluid flow through the clearance  88  introduces a viscous drag and causes a damping effect on the movement of the piston  16  to the retracted state. The movement of the piston  16  is hence inhibited to a degree. The fluid  38  travels through the clearance  88  and then to the low pressure reservoir  48 . The amount of the fluid  38  in the low pressure reservoir  48  is increased as a result, and the air pocket  54  shrinks in size to its compressed state. 
     It is to be understood that the foregoing is a description of one or more embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims. 
     As used in this specification and claims, the terms “e.g.,” “for example,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.