Patent Publication Number: US-2018038464-A1

Title: High-inertia stator assembly for controlling operation of a one-way clutch in a torque converter

Description:
TECHNICAL FIELD 
     The present disclosure relates to a torque converter. More particularly, the present disclosure relates to a high inertia stator assembly for controlling operation of a one-way clutch in a torque converter. 
     BACKGROUND 
     Torque converters are generally used to transmit drive power from a prime mover e.g., an engine or an electric motor to a transmission. Typically, torque converters include an impeller, a turbine, and a stator wheel that is mounted on a one-way clutch interposed between the impeller and the turbine. The stator wheel is held stationary by the one-way clutch during a stall mode or torque multiplication mode while the one-way clutch allows the stator wheel to freewheel during the coupling mode so that fuel efficiency of the prime mover can be increased. 
     In many cases, a one-way clutch typically consists of multiple rollers in which each roller is being biased into a floating position to allow the stator wheel to freewheel in the coupling mode i.e., when a speed of the turbine nearly approaches that of the impeller, the one-way clutch will release so that the stator wheel can now facilitate the turbine to rotate at a speed nearly equal to that of the impeller. In addition, the rollers of the one-way clutch can also be biased into a sliding position in which the stator wheel is allowed to freewheel at a rotational speed less than a pre-determined value of the rotational speed at which centripetal forces on the rollers become sufficient enough to compress corresponding ones of resilient members and move the rollers into the floating position. 
     However, during the stall mode or the torque multiplication mode, differences in speed or torque between the impeller and the turbine can tend to cause the stator wheel and the one-way clutch to counter-rotate in relation to the impeller and the turbine. In these modes of operation, the rollers of the one-way clutch are configured to become engaged to maintain a stationary position of the stator wheel. 
     During operation, the rollers of the one-way clutch are frequently forced to shift from a floating position to an engaged position and vice-versa depending on a relative difference between the rotational speeds of the impeller and the turbine. Moreover, a movement of the rollers between the floating and engaged positions may be rapid enough so as to cause fatigue and/or failure to the rollers over prolonged durations of operation. 
     Hence, there is a need for a stator wheel that overcomes the aforementioned shortcomings. 
     SUMMARY OF THE DISCLOSURE 
     In an aspect of the present disclosure, a stator assembly for a torque converter having an impeller and a turbine includes a one-way clutch. The one-way clutch includes a plurality of rollers arranged radially in a spaced apart relation to one another. Each of the plurality of rollers is biased into a floating position by a corresponding resilient member. The stator assembly also includes a stator wheel mounted on the one-way clutch. A mass of the stator wheel is selected so as to operatively provide a predetermined amount of delay for engaging or disengaging the one-way clutch. 
     In another aspect of the present disclosure, a torque converter includes an impeller, a turbine operatively coupled to the impeller, and a stator wheel mounted on a one-way clutch and interposed between the impeller and the turbine. The one-way clutch has a plurality of rollers arranged radially in a spaced apart relation to one another in which each of the plurality of rollers is biased into a floating position by a corresponding resilient member. A mass of the stator wheel is selected to operatively provide a predetermined amount of delay for engaging or disengaging the one-way clutch. 
     Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side sectional view of a torque converter, in accordance with a first embodiment of the present disclosure; 
         FIG. 2  is a front sectional view of the torque converter showing a stator assembly having a stator wheel mounted on a one-way clutch, in accordance with the first embodiment of the present disclosure; 
         FIG. 3  is an enlarged view of the one-way clutch showing multiple rollers being biased into a floating position by corresponding resilient members, in accordance with embodiments of the present disclosure; 
         FIG. 4  is an enlarged view of the one-way clutch showing multiple rollers in the engaged position, in accordance with embodiments of the present disclosure; 
         FIG. 5  is a side sectional view of the torque converter, in accordance with a second embodiment of the present disclosure; 
         FIG. 6  is a perspective view of the stator assembly, in accordance with the second embodiment of the present disclosure; 
         FIG. 7  is a side sectional view of the torque converter, in accordance with a third embodiment of the present disclosure; and 
         FIG. 8  is a perspective view of the stator assembly, in accordance with the third embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference numerals appearing in more than one figure indicate the same or corresponding parts in each of them. References to elements in the singular may also be construed to relate to the plural and vice-versa without limiting the scope of the disclosure to the exact number or type of such elements unless set forth explicitly in the appended claims. 
     The present disclosure relates to a stator assembly  106  for controlling operation of a torque converter.  FIG. 1  shows a side sectional view of a torque converter  100  in accordance with an embodiment of the present disclosure. The torque converter  100  includes an impeller  102 , a turbine  104  operatively coupled to the impeller  102 , and a stator assembly  106 . The stator assembly  106  includes a stator wheel  108  mounted on a one-way clutch  110  and interposed between the impeller  102  and the turbine  104 . Moreover, as shown, the impeller  102 , the turbine  104 , the stator wheel  108 , and the one-way clutch  110  are disposed within a housing  112  of the torque converter  100 . 
     Further, as shown in the illustrated embodiment of  FIG. 1 , the impeller  102  is formed integrally with the housing  112  of the torque converter  100 . The housing  112  of the torque converter  100  may be coupled to a flexplate (not shown) of a suitable prime mover (not shown) e.g., an engine or an electric motor depending on specific requirements of an application. The turbine  104  is rigidly coupled to a transmission input shaft  116  and configured to rotate the transmission input shaft  116  for delivering drive power from the prime mover to a transmission device (not shown). 
     Referring to  FIGS. 1 and 2 , the one-way clutch  110  includes multiple rollers  118  that are arranged radially in a spaced apart relation to one another. As shown in  FIG. 3 , each of the rollers  118  is biased into a floating position by centripetal force from a rotational speed of the stator wheel  108  against a corresponding resilient member  120  e.g., a compression spring. As known to persons skilled in the art, the floating position of the rollers  118  can facilitate the stator wheel  108  to freewheel during a coupling mode of the torque converter  100 . 
     Referring to  FIG. 4 , each of the rollers  118  is forced away from the corresponding resilient members  120  into an engaged position. The stator wheel  108  can be held stationary by the engaged position of the individual rollers  118  in the one-way clutch  110  during a stall mode or a torque multiplication mode of the torque converter  100 . 
     As known to persons skilled in the art, the rollers  118  have a predetermined amount of inertia and in order to cause a movement of the rollers  118  from the floating position (shown in  FIG. 3 ) to the engaged position (shown in  FIG. 4 ), the operating fluid forces would need to overcome the predetermined amount of inertia associated with the rollers  118  in addition to the biasing forces of the resilient members  120  while a movement of the rollers  118  from the engaged position (shown in  FIG. 4 ) to the floating position (refer to  FIG. 3 ) may be accomplished when the operating fluid forces accelerate the stator wheel  108  sufficiently to exceed the biasing force of the corresponding resilient member  120  i.e., when the stator wheel  108  has reached sufficient speed to generate centripetal force on the rollers  118  to oppose the bias force of the corresponding resilient members  120 . 
     In addition to the floating and engaged positions disclosed herein, the rollers  118  of the one-way clutch  110  can also be biased into a sliding position in which the stator wheel  108  is allowed to freewheel at a rotational speed less than a pre-determined value of the rotational speed at which centripetal forces on the respective rollers  118  become sufficient enough to compress corresponding ones of the resilient members  120  and move the rollers into the floating position. A rapidity with which the one-way clutch  110  engages or disengages depends on a speed of movement associated with the rollers  118  given the amount of inertia associated with each of the rollers  118  and the biasing force of the corresponding resilient members  120 . 
     In embodiments of this disclosure, it is contemplated that a mass of the stator wheel  108  is selected so as to operatively provide a predetermined amount of delay for engaging or disengaging the one-way clutch  110 . This way, a deceleration of the stator wheel  108  occurs such that the predetermined amount of delay operatively provided by the mass of the stator wheel  108  is greater than or at least equal to a minimum amount of time required for each of the plurality of rollers  118  to move from the floating position to an engaged position. 
     If the minimum amount of time required for the rollers  118  of the one-way clutch  110  to move from their respective floating positions to their respective engaged positions is represented by T float-engage , and the predetermined amount of delay in deceleration of the stator wheel  108  from its current operating speed to a value corresponding to the engaged positions of the respective rollers  118  is represented by D disengage-engage , then D disengage-engage ≧T float-engage . Therefore, by virtue of the mass of the stator wheel  108 , a deceleration of the stator wheel  108  can be configured to provide an adequate amount of time for the rollers  118  to shift from their respective floating positions to their respective engaged positions i.e., the predetermined amount of delay in deceleration of the stator wheel  108  D disengage-engage  is greater than or at least equal to the minimum amount of time T float-engage  required by the rollers  118  to move from the floating position to an engaged position. 
     Further, in embodiments of this disclosure, it is also contemplated that an acceleration of the stator wheel  108  occurs such that the predetermined amount of delay operatively provided by the mass of the stator wheel  108  is greater than or at least equal to a minimum amount of time required for each of the plurality of rollers  118  to move from an engaged position to the floating position. If the minimum amount of time required for the rollers  118  of the one-way clutch  110  to move from their respective engaged positions to their respective floating positions is represented by T engage-float , and the predetermined amount of delay in acceleration of the stator wheel  108  from its current operating speed to a value corresponding to a floating speed of the respective rollers  118  is represented by D engage-disengage , then D engage-disengage ≧T engage-float . Therefore, by virtue of the mass of the stator wheel  108 , the acceleration of the stator wheel  108  can be reduced such that the predetermined amount of delay in acceleration of the stator wheel  108  D engage-disengage  is greater than or at least equal to the minimum amount of time T engage-float  required by the rollers  118  to move from their respective engaged positions to their respective floating positions. This way, the predetermined amount of delay D engage-disengage  in the acceleration of the stator wheel  108  from its current operating speed to a value corresponding to a floating speed of the respective rollers  118  provides adequate amount of time for the rollers  118  to shift from their respective engaged positions to their respective floating positions i.e., D engage-disengage ≧T engage-float . 
     Furthermore, in another embodiment of this disclosure, the outer race  114  of the one-way clutch  110  includes a plurality of cam surfaces  117  as shown in  FIG. 2 . Each cam surface  117  is configured to establish contact with a corresponding roller  118  according to a rotational speed of the stator wheel  114 . When the rotational speed of the stator wheel  108  is elevated, the rollers  118  from the one-way clutch  110  are subject to centripetal force due to which the rollers  118  are configured to compress corresponding ones of the resilient members  120 . While it is possible that the resilient members  120  may have load and rate variance from one resilient member  120  to another so as to cause the resilient members  120  having low preload to be compressed more than a remainder of the resilient members  120  that have a high preload associated therewith, upon rapid engagement of the one-way clutch  108 , some of the cam surfaces  117  from the outer race  114  could be biased off-center even though all the rollers  118  are in their respective engaged positions. As a result, only a remainder of the cam surfaces  117  from the outer race  114  of the one-way clutch  110  would be able to take up load against the corresponding rollers  118  on the opposing side. However, with implementation of embodiments disclosed herein, a mass of the stator wheel  108  so selected beneficially causes the corresponding inertia of the stator wheel  108  to allow each of the cam surfaces  117  to center with the corresponding rollers  118  prior to engagement with the rollers  118 . This way, it is envisioned that the mass and corresponding inertia of the stator wheel  108  provide sufficient amount of time to allow an increased number of rollers  118  to appropriately center with the corresponding cam surfaces  117  of the outer race  114  and consistently take up the load upon engagement. 
     In embodiments of this disclosure, the stator wheel  108  can be formed from one of a ferrous material e.g., cast iron, steel etc., or a non-ferrous material e.g., aluminum, bronze, or other materials commonly known in the art. Although non-ferrous materials such as aluminum and bronze are disclosed herein, a type of material used to form the stator wheel  108 , and therefore impart mass to the stator wheel  108  for reducing the acceleration and deceleration of the stator wheel  108 , may vary from one application to another depending on specific requirements of an application. 
     In another embodiment as shown in  FIGS. 5-6 , the stator wheel  108  is provided with a ring  122  disposed on an outer circumference  124  of the stator wheel  108 . The ring  122  is configured to increase an amount of inertia associated with the stator wheel  108 . It will be acknowledged that an amount of increase in the inertia of the stator assembly  106  is now dependent i.e., proportional to the mass of the stator wheel  108  and the added mass of the ring  122 . Moreover, as shown in  FIG. 5 , the ring  122  is configured to advantageously protrude into an annular region  128  defined between the impeller  102  and the turbine  104  of the torque converter  100 . This way, the ring  122  can be conveniently accommodated within the annular region  128  defined between the impeller  102  and the turbine  104 . 
     Moreover, as shown in the illustrated embodiment of  FIGS. 5-6 , the ring  122  may be integrally formed with the stator wheel  108 . It can be contemplated by way of embodiments herein to form the stator wheel  108  and the ring  122  from similar or dissimilar materials. In an example where dissimilar materials are used, the stator wheel  108  may be formed from aluminum while the ring  122  may be formed from cast iron. In another example, both the stator wheel  108  and the ring  122  may be formed from cast iron. It can also be contemplated to form the ring  122  using a material having a higher density compared to that of the stator wheel  108 . Therefore, it will be appreciated that various materials can be advantageously used to form the stator wheel  108  and the ring  122  to meet specific requirements of an application. 
     In yet another embodiment, the ring  122  may be coupled to the stator wheel  108  by using at least one of bolting, welding, keying, a retaining mechanism, an interference fit, and a threaded fit. As shown in the illustrated embodiment of  FIGS. 7-8 , the ring  122  and the stator wheel  108  are formed independently of one another and are mutually coupled with the help of bolts  126 . Moreover, similar to the preceding embodiment of  FIG. 5 , the ring  122  in this embodiment can also be configured to advantageously protrude within the annular region  128  defined between the impeller  102  and the turbine  104  as shown in  FIG. 7 . 
     In the embodiments of  FIGS. 5-6  and  FIGS. 7-8 , the ring  122  is configured to increase an amount of inertia associated with the stator wheel  108  so that acceleration and deceleration of the stator wheel  108  may be reduced to a value that allows sufficient time for the rollers  118  of the one-way clutch  110  to execute movement between their respective engaged and floating positions or vice-versa. With use of the embodiments disclosed in conjunction with  FIGS. 5-6  and  FIGS. 7-8 , persons skilled in the art can also beneficially vary the amount of predetermined delay to provide for the minimum amount of time required by the rollers  118  to shift from their respective floating positions to their respective engaged positions and vice-versa i.e., D disengage-engage ≧T float-engage  and D engage-disengage ≧T engage-float . 
     In embodiments of this disclosure, although it has been contemplated to increase the inertia of the stator assembly wheel  106  by increasing a mass of the stator wheel  108  and/or by providing the ring  122  to the stator wheel  108 , it can also be contemplated to change or alter a section geometry of the stator wheel  108  e.g., by adding mass at locations other than at the outer circumference  124  of the stator wheel  108  disclosed herein such that an inertia associated with the stator wheel  108  is configured to provide adequate time for the rollers  118  to perform functions consistent with this disclosure. Therefore, although embodiments herein are directed to the ring  122  at the outer circumference  124  of the stator wheel  108 , it will be appreciated that various methods of increasing an inertia of the stator wheel  108  can be contemplated by persons skilled in the art without deviating from the spirit of the present disclosure. 
     Moreover, although some components typically present in conventionally known torque converters have been omitted from the configuration of the torque converter  100  disclosed herein for the sake of simplicity and convenience in understanding the present disclosure, it may be noted that embodiments of the present disclosure are not limited to the specific configuration of the torque converter  100  disclosed herein. In fact, it will be appreciated by persons skilled in the art that embodiments of the present disclosure can be similarly applied in various other configurations of torque converters having one or more additional components including, but not limited to, a lock-up clutch, an impeller clutch, a torque divider, and/or a stator clutch which by way of example is described in U.S. Pat. No. 8,939,859. 
     Further, persons skilled in the art will recognize that a configuration of the one-way clutch  110  described in this document is only one of many possible configurations known in the art for accomplishing the locked, transition and freewheel modes of operation. Therefore, it may be noted that a specific configuration of the one-way clutch disclosed herein is non-limiting of this disclosure. Rather, it will be appreciated by persons skilled in the art that embodiments disclosed herein may be similarly applied to numerous other configurations of one-way clutches known in the art without deviating from the spirit of the present disclosure. 
     Various embodiments disclosed herein are to be taken in the illustrative and explanatory sense, and should in no way be construed as limiting of the present disclosure. All joinder references (e.g., attached, affixed, coupled, engaged, meshed, connected, and the like) are only used to aid the reader&#39;s understanding of the present disclosure, and may not create limitations, particularly as to the position, orientation, or use of the systems and/or methods disclosed herein. Therefore, joinder references, if any, are to be construed broadly. Moreover, such joinder references do not necessarily infer that two elements are directly connected to each other. 
     Additionally, all numerical terms, such as, but not limited to, “first”, “second”, “third”, or any other ordinary and/or numerical terms, should also be taken only as identifiers, to assist the reader&#39;s understanding of the various elements, embodiments, variations and/or modifications of the present disclosure, and may not create any limitations, particularly as to the order, or preference, of any element, embodiment, variation and/or modification relative to or over another element, embodiment, variation and/or modification. 
     It is to be understood that individual features shown or described for one embodiment may be combined with individual features shown or described for another embodiment. The above described implementation does not in any way limit the scope of the present disclosure. Therefore, it is to be understood although some features are shown or described to illustrate the use of the present disclosure in the context of functional segments, such features may be omitted from the scope of the present disclosure without departing from the spirit of the present disclosure as defined in the appended claims. 
     INDUSTRIAL APPLICABILITY 
     Embodiments of the present disclosure have applicability for use and implementation in controlling an operation of a torque converter. With use of previously known torque converters, a rapidity in the movement of rollers associated with a one-way clutch was known to cause premature fatigue and/or failure of the rollers. With use of embodiments disclosed herein, manufacturers can prolong a service life of the rollers in the one-way clutch while continuing to accomplish a smooth shift of drive power from the prime mover to the transmission input shaft. 
     Moreover, embodiments disclosed in conjunction with  FIGS. 5-6  and  FIGS. 7-8  can be used to conveniently retro-fit the ring  122  to an existing stator wheel of a given torque converter for increasing the inertia of the stator assembly and hence, reducing the acceleration and deceleration of the stator assembly. Reduction in the acceleration and deceleration of the stator assembly provides sufficient amount of time for the rollers to shift from their current positions into their respective engaged or floating positions as required. As the rollers  118  can now shift into their respective engaged or floating positions in the sufficient amount of time provided by the predetermined amount of delay i.e., D disengage-engage  or D engage-disengage , a rapidity in the movement of the rollers can be mitigated to help reduce fatigue and/or failure of the one-way clutch. Further, a service life of the rollers in the one-way clutch may be improved with use of embodiments disclosed herein. 
     Also, the ring  122 , as disclosed in the embodiments of  FIGS. 5-6  and  FIGS. 7-8 , can be accommodated within an annular region typically defined between the impeller and the turbine, manufacturers may entail little or no additional modifications to an existing torque converter during the installation of the stator assembly  106  disclosed herein. 
     While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems, methods and processes without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.