Patent Publication Number: US-2023134946-A1

Title: Hydraulic powertrain component mount with variable stiffness

Description:
FIELD 
     The present disclosure relates to a powertrain mount that includes hydraulic fluid and a valve operable to change the stiffness of the mount. 
     BACKGROUND 
     Vehicle powertrain components are coupled to a structural assembly of the vehicle by a plurality of mounts, at least some of which may be compliant to damp forces and vibrations transmitted in the vehicle. Mounts having a single stiffness must be designed to handle high torque loads and thus, may be stiffer than desired in managing other loads between the vehicle and powertrain component(s). Soft mounts do not adequately dissipate forces and vibrations during some vehicle operating conditions or events, like restarting a vehicle engine by a vehicle start-stop system. 
     SUMMARY 
     In at least some implementations, a powertrain component mount assembly includes a housing, a main rubber element (MRE), a hydraulic body, a membrane and a valve. The MRE has an outer armature, an inner armature and an isolating element coupled to the outer armature and to the inner armature, the isolating element being formed of a material that is more flexible than the outer armature and the inner armature to permit relative movement between the inner armature and the outer armature, wherein the main rubber element defines at least part of a fluid flow path having a first end and a second end. The hydraulic body is connected to the housing and supports the outer armature of the MRE, the hydraulic body defines part of the fluid flow path, a fluid chamber that is communicated with the fluid flow path, and part of a control chamber communicated with the fluid flow path between the first end and the fluid chamber, and the hydraulic body has a port open to the control chamber. The membrane defines part of the control chamber and is arranged between the port and the fluid flow path. The valve has a valve head movable relative to the port between a first position closing the port and a second position spaced from the port. 
     In at least some implementations, the valve is electrically operated and the valve head is moved relative to the port in response to application of electricity to the valve. 
     In at least some implementations, the membrane is carried by and sealed to the hydraulic body. In at least some implementations, part of the membrane moves relative to the port, and wherein when the valve head is in the second position and fluid in the fluid flow path acts on the membrane, the membrane flexes relative to the fluid flow path and inhibits or prevents fluid flow in the fluid flow path. In at least some implementations, when the valve head is in the first position air in the control chamber cannot exit the control chamber through the port and the membrane is inhibited or prevented from movement toward the port, and the membrane permits fluid flow in the fluid flow path. In at least some implementations, movement between the inner armature and the outer armature is suppressed when the valve head is in the first position compared to when the valve head is in the second position. 
     In at least some implementations, the valve is electrically operated, the valve head is in the second position when electricity is not supplied to the valve, and the valve head is moved to the first position when electricity is supplied to the valve. 
     In at least some implementations, the housing includes a first connection point adapted to be connected to one of a vehicle structural component or a powertrain component, and the inner armature includes a second connection point adapted to be connected to the other of the vehicle structural component or powertrain component. 
     In at least some implementations, the fluid flow path is defined between overlapped surfaces of the outer armature, the hydraulic body, and a fluid flow path cover, the fluid flow path being defined in part by a groove formed in the hydraulic body. In at least some implementations, the fluid in the fluid flow path is a hydraulic liquid. 
     In at least some implementations, air is present within the control chamber and when the valve head is in the first position the valve head inhibits or prevents air from flowing through the port to inhibit or prevent movement of the membrane. 
     In at least some implementations, the assembly includes an accumulator body coupled to the hydraulic body and defining part of the fluid chamber, the accumulator body having at least a portion that moves the change the volume of the fluid chamber. 
     In at least some implementations, a vehicle assembly includes a structural component, a powertrain component and a mount. The mount is connected at a first connection point to the structural component and at a second connection point to the powertrain component. The mount includes a housing including the first connection point, a MRE, a hydraulic body, a membrane and a valve. The MRE has an outer armature, an inner armature including the second connection point, and an isolating element coupled to the outer armature and to the inner armature, the isolating element being formed of a material that is more flexible than the outer armature and the inner armature to permit relative movement between the outer armature and inner armature, wherein the main rubber element defines at least part of a fluid flow path having a first end and a second end. The hydraulic body is connected to the housing and supports the outer armature of the MRE. The hydraulic body defines part of the fluid flow path, at least part of a fluid chamber, part of a control chamber communicated with the fluid flow path between the first end and the fluid chamber, and the hydraulic body has a port open to the control chamber. The membrane defines part of the control chamber and is arranged between the port and the fluid flow path so that fluid in the fluid flow path does not flow through the port. And the valve has a valve head movable relative to the port between a first position closing the port and a second position spaced from the port. 
     In at least some implementations, air is present within the control chamber and when the valve head is in the first position the valve head inhibits or prevents air from flowing through the port to inhibit or prevent movement of the membrane. In at least some implementations, the membrane is carried by and sealed to the hydraulic body. 
     In at least some implementations, the membrane is formed from an elastic material and part of the membrane moves relative to the port, and wherein when the valve head is in the second position and fluid in the fluid flow path acts on the membrane, the membrane flexes relative to the fluid flow path and inhibits or prevents fluid flow in the fluid flow path. In at least some implementations, when the valve head is in the first position air in the control chamber cannot exit the control chamber through the port and the membrane is inhibited or prevented from movement toward the port, and the membrane permits fluid flow in the fluid flow path. In at least some implementations, movement between the inner armature and the outer armature is suppressed when the valve head is in the first position compared to when the valve head is in the second position. 
     Further areas of applicability of the present disclosure will become apparent from the detailed description, claims and drawings provided hereinafter. It should be understood that the summary and detailed description, including the disclosed embodiments and drawings, are merely exemplary in nature intended for purposes of illustration only and are not intended to limit the scope of the invention, its application or use. Thus, variations that do not depart from the gist of the disclosure are intended to be within the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view showing a portion of a vehicle structural assembly, a portion of a powertrain component and a mount coupling the powertrain component to the structural assembly; 
         FIG.  2    is another perspective view of the components shown in  FIG.  1   ; 
         FIG.  3    is a sectional view of the mount; 
         FIG.  4    is a perspective view of the mount; 
         FIG.  5    is another perspective view of the mount showing an accumulator body and a valve carried by the mount; 
         FIG.  6    is a side view of the mount; 
         FIG.  7    is a perspective view of a hydraulic body of the mount showing an upper surface of the hydraulic body; 
         FIG.  8    is a perspective view of the hydraulic body with a cover over the upper surface; and 
         FIG.  9    is a perspective view of a main rubber element of the mount, showing a bottom surface of an outer armature. 
     
    
    
     DETAILED DESCRIPTION 
     Referring in more detail to the drawings,  FIG.  1    shows a portion of a motor vehicle including a portion of a vehicle structural assembly  10 , part of a powertrain component  12  and a mount  14  by which the powertrain component  12  is coupled to the structural assembly  10 . The portion of the vehicle structural assembly  10  shown includes two main structural components, called herein upper and lower frame members  16 ,  18 , and also other brackets  20  and connectors for various vehicle components. The portion of the powertrain component  12  shown in  FIGS.  1  and  2    is part of a housing  22  for a vehicle transmission  12 , although the mount  14  may be used to couple other powertrain components (e.g. an engine) to the vehicle structural assembly  10 . In at least some implementations, the powertrain component  12  (e.g. engine and/or transmission) is mounted transversely, and the upper and lower frame members  16 ,  18  shown in  FIGS.  1  and  2    are oriented in a cross-car direction, perpendicular to a forward direction of travel of the vehicle. Of course, other arrangements may be used, as desired. As set forth in more detail below, the mount  14  includes compliant components that damp vibrations and forces that would otherwise be distributed from the transmission to the structural components  16 ,  18 . 
     As shown in more detail in  FIGS.  3 - 6   , the mount  14  includes a housing  24 , a main rubber element (MRE)  26  and a hydraulic body  28  carried by the housing  24 . The housing  24  has a first connection point  30  by which the housing  24  is coupled to one of the powertrain components  12  or structural assembly  10 . In the example shown in the drawings, the housing  24  includes a flange  32  that extends outwardly and the first connection point  30  is defined by an opening  34  through the flange  32 . As shown in  FIG.  1   , a connector such as a bolt  36  extends through the opening  34  and is coupled to the transmission housing  22  such that the flange  32  is trapped between a head of the bolt  36  and the transmission housing  22 . A bushing  38  or other compliant member may be received in the opening  34 , and the bolt  36  may extend through the bushing  38  for a compliant, vibration-damped connection between the bolt  36  and housing  24 . 
     The housing  24  may include two sidewalls  40  coupled together at a first end  42  by a base  44  providing a generally U-shaped housing  24 , with the flange  32  extending from a side  46  of the base  44  opposite to the side  48  that defines part of an area in which the MRE  26  is received. The sidewalls  40  may each extend to a second end  50 , and the second ends  50  of the sidewalls  40  may be spaced apart from each other. The mount  14  may be connected to one or both of the upper and lower frame members  16 ,  18 . In the example shown, at least part of the housing  24  is received between the frame members  16 ,  18 , and the mount  14  is coupled to both frame members by a connector, such as a bolt  52  ( FIGS.  1  and  2   ), extending through the frame members and the MRE  26 . 
     The MRE  26  is received between the housing  24  sidewalls  40  and in use, at least part of the MRE  26  moves relative to the housing  24 . The MRE  26  has an outer armature  54  carried by or constrained by the housing  24 , an inner armature  56 , and an isolating element  58  coupled to the outer armature  54  and to the inner armature  56 . The outer armature  54  is connected to and supports the isolating element  58  which in turn is connected to and supports the inner armature  56  such that the inner armature  56  is not directly engaged with the outer armature  54  and is indirectly connected to the outer armature  54  via the isolating element  58 . To permit relative movement between the inner armature  56  and both the outer armature  54  and the housing  24 , the isolating element  58  is formed of a material that is more flexible or compliant than is the outer armature  54  and the inner armature  56 . For example, the isolating element  58  may be formed of an elastomer like rubber (which may be reinforced as desired) and may be overmolded onto the outer armature  54  and over or around the inner armature  56 . In at least some implementations, such as is shown and labeled in  FIG.  4   , the isolating element  58  may include a layer  59  of material overlying all or part of an end face  60  of the outer armature  54 , a web  62  of material extending between the outer armature  54  and the inner armature  56 , and a layer  63  of material surrounding at least part of the exterior of the inner armature  56 . In at least some implementations, the isolating element  58  does not cover opposite first and second end faces  64 ,  66  of the inner armature  56 , but does cover most or all of the sidewall  68  of the inner armature  56  which defines a periphery of the inner armature  56  and extends between the end faces  64 ,  66 . In the example shown, the web  62  of the isolating element  58  has a thickness less than the distance between the end faces  64 ,  66  of the inner armature  56 , and less than the thickness of first and second end faces  60 ,  70  of the outer armature  54 . The thickness and material properties of the web  62  can be adjusted as desired to change the damping properties thereof, and change the magnitude of movement of the inner armature  56  relative to the outer armature  54  under a given force. So arranged, the inner armature  56  does not directly engage the outer armature  54  and the flexible isolating element  58  permits movement of the inner armature  56  relative to the outer armature  54 . 
     The inner armature  56  may be suspended within the housing  24  by the isolating element  58  so that the inner armature  56  is separate from and not directly connected to the housing  24 , and the inner armature  56  may move relative to the housing  24 . The inner armature  56  may be formed of metal or other material capable of handling the loads on the inner armature  56 . To connect the mount  14  to either the powertrain component  12  or one or both of the structural members  16 ,  18 , the inner armature  56  includes a second connection point  72 . In the example shown, the second connection point  72  is a hole in or through the inner armature  56 , shown as a hole  72  extending through the end faces  64 ,  66 , spaced inwardly from the periphery of the inner armature  56 . In assembly, the bolt  52  is received in the hole  72  and couples the inner armature  56  to the structural member(s)  16  and/or  18 . So arranged, forces and vibrations from the transmission housing  22  are transmitted to the structural component(s)  16  and/or  18  via the MRE  26 , wherein the flexible isolating element  58  provides a damped connection (as does any bushing  38  or compliant member between the housing  24  and bolt  36 ). Movement of the inner armature  56  relative to the housing  24  may be limited by surfaces of the housing  24 , which may be engaged by the MRE  26  as relative movement occurs between the housing  24  and inner armature  56 . To damp noise and forces from engagement of the MRE  26  with the housing  24 , surfaces of the inner armature  56  that may engage the housing  24  may be coated by a compliant member which may be a portion of the isolating element  58  as described above, or separate or discrete compliant members, as desired. In the example shown, the hole  72  extends perpendicularly to the opening  34  in the housing  24 , although other orientations may be used. 
     The outer armature  54  of the MRE  26  may be constrained against movement by the housing  24 , and by the hydraulic body  28  that is coupled to the housing  24 . In at least some implementations, to couple the hydraulic body  28  and outer armature  54 , the outer armature  54  has, spaced about its periphery, a plurality of voids  53  ( FIGS.  4 ,  5  and  9   ) with retaining surfaces  55  ( FIG.  9   ), and the hydraulic body  28  includes a plurality of fingers  57  ( FIGS.  4 ,  5 ,  7  and  8   ) adapted to be partially received in the voids  53  and having latches  59  ( FIGS.  7  and  8   ) that are snap-fit over and retained by the retaining surfaces  55 . In the example shown, the housing  24  includes ribs  74  that extend inwardly from the sidewalls  40 , and the outer armature  54  is trapped between these ribs  74  and the hydraulic body  28 . To damp vibrations, damping material, which may be material of the isolating element  58 , may be provided between the outer armature  54  and the ribs  74  (e.g. by overmolding that portion of the outer armature  54  with the material of the isolating element  58 ). A cavity  76  ( FIG.  3   ) may be formed in the end face  60  of the outer armature that is closest to the inner armature  56 , and the cavity  76  may be partially circular, such as semi-circular. A portion of the inner armature  56  may extend into the cavity  76  but remain spaced from the end face  60 , for example, a portion of the inner armature  56  may intersect a plane  78  ( FIG.  3   ) parallel to and including the end face  60  of the outer armature  54 . The web  62  between the first and inner armatures  54 ,  56  may follow the contour of the outer armature  54  and extend around the adjacent portion of the inner armature  56  providing support for the inner armature  56  (via attachment of the web  62 ) over an angular range of between 90 and 360 degrees. 
     As shown in  FIG.  3   , the outer armature  54  of the MRE  26 , the hydraulic body  28  and a fluid flow path cover  85  define at least part of a fluid flow path  80  having a first end  82  and a second end  84 . The first end  82  of the fluid flow path  80  may lead to or be defined in part by the isolating element  58  of the MRE  26 , which, with the outer armature  54  and cover  85 , may define a first fluid chamber  86  between them. The second end  84  of the fluid flow path  80  may lead to or be defined by a second fluid chamber  88  defined at least partially between the cover  85  and the hydraulic body  28 . Between the ends, the fluid flow path  80  may be defined by a passage created by one or more of the outer armature  54 , the cover  85  and hydraulic body  28 . In at least some implementations, such as the one shown in the drawings, the fluid flow path  80  is defined in part by a groove  90  ( FIGS.  3  and  7   ) formed in the face  92  of the hydraulic body  28  that is overlapped by the cover  85 . As shown in  FIG.  7   , the groove  90 , for example at a first end  97  of the groove, leads to a port  93  in the hydraulic body  28  that is open to the second fluid chamber  88  and which is overlapped/enclosed by the cover  85 . Spaced from the port  93 , for example at a second end  99  of the groove  90 , the groove  90  leads to or is otherwise communicated with an opening  95  ( FIGS.  3  and  8   ) through the cover  85  that is open to or otherwise communicated with the first fluid chamber  86 . Thus, fluid flows between the fluid chambers  86 ,  88  through the fluid flow path  80 . The fluid flow path  80  may be a convoluted, serpentine or spiral flow path, as desired to provide a desired fluid flow resistance for a given force input. A liquid (e.g. a hydraulic liquid) is received within the fluid flow path  80  and liquid flows between the first fluid chamber  86  and second fluid chamber  88  and within the groove  90  when there is relative movement between the housing  24  and the second and isolating elements  56 ,  58  of the MRE  26 , as will be described in more detail later. 
     The hydraulic body  28 , as stated above, is coupled to the housing  24  and to the outer armature  54  of the MRE  26 . In the example shown, the second ends  50  of the housing  24  sidewalls  40  are bent around an outer end of the hydraulic body  28 , with the MRE  26  outer armature  54  and hydraulic body  28  trapped together between the ribs and second ends  50  of the sidewalls  40 . As shown in  FIG.  3   , a first void  94  in the hydraulic body  28  defines part of the second fluid chamber  88 . The first void  94  extends into the hydraulic body  28  from an outer face  96 . The first void  94  is enclosed at its open end by an accumulator body  98  that is coupled to the hydraulic body  28  (to define an accumulator) and is open to the port  93 . A second void  100  in the hydraulic body  28 , spaced from the first void  94 , defines part of a control chamber  102 . A port  104  extends between the second void  100  and a valve cavity  106  in which a valve  108  is received. 
     The accumulator (herein referred to as an accumulator body)  98  may be a flexible, diaphragm type body sealed about its periphery to the hydraulic body  28  and having a convolution or bellows  110  spaced from the periphery that permits a portion of the accumulator body  98  to move relative to the hydraulic body  28 . The accumulator body  98  may be formed from an elastomeric material, such as rubber, and may be spring biased to alter the pressure or force needed to cause a given amount of movement of the accumulator body  98 . In the example shown, no spring is used and the exterior of the accumulator body  98  is open to the ambient environment and acted upon by ambient/atmospheric pressure. Movement of the accumulator body  98  changes the volume of the second fluid chamber  88  to accommodate movement of liquid between the first fluid chamber  86  and second fluid chamber  88 . 
     The valve  108  includes a valve head  112  that is movable relative to the port  104  from a first position wherein fluid flow through the port  104  is inhibited or prevented, to a second position in which the valve head  112  is spaced from the port  104  and a greater fluid flow rate is possible through port  104 . In at least some implementations, the valve  108  is a solenoid valve which changes the position of the valve head  112  when electricity is supplied to the valve  108 . In at least some implementations, the valve head  112  is in the second position when electricity is not supplied to the valve  108 , and the valve head  112  is moved to the first position when electricity is supplied to the valve  108 . Of course, other arrangements and control schemes may be used as is known with solenoid valve  108   s . The valve  108  may include a housing  114  that is at least partially received in the valve cavity  106 , and the valve  108  may be connected to and totally supported by the hydraulic body  28 , if desired. To facilitate electrically connecting the valve  108 , an end of the valve  108  may be exposed from the outer end of the hydraulic body  28 . 
     Finally, a membrane  116  may be received between the cover  85  and the hydraulic body  28 . In at least some implementations, the membrane  116  is a circular disc of flexible material that is carried by and sealed about its periphery to the hydraulic body  28  overlying the second void  100 , and with the cover  85 , defines the control chamber  102  on one side of the membrane  116 . The opposite side of the membrane  116  is communicated with and may define part of the fluid flow path  80 , such as by a passage or port  117  formed through the plate as shown in  FIGS.  3 ,  8  and  9   . Alternatively, as shown in  FIG.  7   , the cover  85  may extend over only the groove and not also over the membrane  116 . The membrane  116  is impervious to the liquid in the fluid flow path  80  such that the control chamber  102  is devoid of liquid and instead air is received in the control chamber  102 . In at least some implementations, the membrane  116  is located in or at a portion of the fluid flow path  80  that is between the first fluid chamber  86  and second fluid chamber  88 , and the membrane  116  is arranged to control fluid flow through the fluid flow path  80  and between the fluid chambers. 
     In more detail, when the valve head  112  is in the second position, fluid flowing in the fluid flow path  80  acts on the membrane  116  and moves the membrane  116  relative to the fluid flow path  80 . Movement of the membrane  116  is permitted as the port  104  is open and air can flow in and out of the control chamber  102  as the membrane  116  moves. Movement of the membrane  116 , which may be toward and away from the port  104 , interferes with liquid flow in the fluid flow path  80 , for example, by causing turbulence in the flow which inhibits or prevents fluid flow in the fluid flow path  80  and between the fluid chambers  86 ,  88 . In this state, the mount  14  is soft as the additional compliance beyond the flexibility of the isolating element  58  of the MRE  26 , which is provided by the flowing liquid in the mount  14 , is lessened or prevented. 
     When the valve head  112  is in the first position, which in the implementation shown occurs when electricity is supplied to the valve  108 , the valve head  112  inhibits or prevents air from flowing through the port  104 . Air is thus trapped in the control chamber  102  and movement of the membrane  116  is inhibited or prevented. Without movement, or at least significant movement of the membrane  116 , fluid flow in the fluid flow path  80  is not interrupted or inhibited. In this state, the mount  14  is stiffer as movement of the MRE  26  occurs more less easily as such MRE  26  movement displaces liquid in the fluid flow path  80 . Such fluid flow may cause additional liquid to be received in the second fluid chamber  88 , with corresponding movement/expansion of the accumulator body  98 , which may provide a return force on the liquid when the pressure/forces in the mount  14  permit such movement. 
     The state of the valve  108 , and hence the state of the mount  14 , can be changed as desired to provide a desired stiffness of the mount  14  in a wide range of vehicle operating conditions. For example, many modern vehicles include electric stop-start systems that turn the engine off when the vehicle is stopped, and start the engine up again to permit continued driving of the vehicle. In these situations, the valve  108  can be actuated to cause the valve head  112  to be in the first position, which provides a stiffer, less compliant mount  14 . Then, when staying in this state and when the vehicle starter is actuated to restart the engine, the attendant harsh vibrations from the starter pulse and initial engine turnover can be better accommodated and damped by the mount  14 . This reduces vibrations and noise upon engine restarting so that such vibrations and noise are less noticeable by vehicle occupants. 
     Thereafter, the valve  108  may be deactuated (electricity no longer supplied thereto) to cause or permit the valve head  112  to move to the second position, which provides a softer, more compliant mount  14 . In this state, the mount  14  is better able to handle higher torque loads that may occur in higher speed driving of the vehicle. 
     Accordingly, a control scheme may be employed to provide the mount  14  in a desired state based upon an instantaneous or anticipated vehicle operating condition. In low speed driving, or when the vehicle is coasting, or when the vehicle is in an engine idle situation, or in any other situation when a more compliant mount  14  is desirable, the valve  108  may be actuated so that the mount  14  is less stiff and more compliant. In other driving conditions when a stiff mount  14  is needed to manage high torque loads in the system, the valve head  112  may be moved or permitted to move to its first position. 
     Further, the mount  14  may be calibrated or tuned to provide a desired damping response. The volume of hydraulic liquid in the system, shape, length and size of the fluid flow path  80 , accumulator body  98  characteristics (e.g. resiliency, stiffness) and other factors may be adjusted as desired. The controllable mount  14  can enable elimination of other components, like transmission auxiliary pumps and/or cam shaft e-phasers, which may be used in some applications to counter vehicle vibrations and torque reactions.