Patent Publication Number: US-11396843-B2

Title: Cranktrain phase adjuster for variable compression ratio

Description:
INCORPORATION BY REFERENCE 
     This application claims priority to U.S. Provisional Application No. 63/027,977, which was filed on May 21, 2020, and is incorporated herein by reference in its entirety. 
    
    
     FIELD OF INVENTION 
     This disclosure is generally related to a cranktrain phase adjuster that can vary a compression ratio of an internal combustion (IC) engine. 
     BACKGROUND 
     Variable compression ratio (VCR) adjustment in IC engines is generally used in order to achieve greater efficiency and improved fuel consumption than an engine with a fixed compression ratio. VCR adjustment systems can rely on a variety of structures and configurations to vary the compression ratio. 
     Known VCR adjustment systems are typically either expensive, complicated to integrate with the engine components or require significant space to be installed. 
     It would be desirable to provide an affordable and compact phase adjuster assembly for a cranktrain to implement VCR in an IC engine. 
     SUMMARY 
     In one aspect, a phase adjuster is disclosed herein that is compact and completely variable. In one aspect, the phase adjuster is configured to adjust a phase between a driving component and driven component of an internal combustion engine. The phase adjuster assembly includes an input gear configured to be driven by the driving component and an output gear configured to drive the driven component. 
     A piston plate assembly is configured to adjust a phase between the driving component and the driven component via axial displacement of the piston plate assembly, according to one aspect. 
     A hydraulic fluid system is configured to selectively provide hydraulic fluid to a first piston control chamber on a first side of the piston plate assembly or to a second piston control chamber on a second side of the piston plate assembly to axially displace the piston plate assembly such that a phase between the driving component and the driven component is adjusted. 
     In one aspect, the output gear is connected to a hub, and the hub defines apply ports and release ports that are selectively fluidly connected to the first piston control chamber and the second piston control chamber. 
     The phase adjuster assembly can further include a spool valve that is axially displaceable to control fluid flow relative to the apply ports and the release ports. The spool valve can be arranged radially inside of the hub. 
     A spool spring can be configured to engage the spool valve, and a return spring can be configured to engage the piston plate assembly. The spool spring can be configured to bias the spool valve in a first axial direction, and the return spring biases the piston plate assembly in a second axial direction opposite from the first axial direction. In one aspect, the return spring has a first end engaging the piston plate assembly and a second end engaging a support plate. 
     A spool piston control chamber can be defined between the spool valve and a valve body housing, in one aspect. The valve body housing can include a control hydraulic line and flow passages that are configured to direct fluid into the spool piston control chamber depending on a relative position of a control valve. 
     In one aspect, an outer chamber is defined at least partially between an output housing and a valve body housing in an outer direction, and a drive plate and a support plate in an inner direction. The outer chamber can be configured to receive fluid via a restricted flowpath from the spool piston control chamber. The support plate can include a first end supported on a bushing mounted on the hub, and a second end of the support plate can be connected to the input gear. 
     In one aspect, the input gear is connected to a support plate and a drive plate, and the drive plate defines roller pockets for a roller-ramp assembly. The drive plate can define an interior boundary for an outer fluid chamber, and the drive plate can define an exterior boundary for at least one piston control chamber. 
     The driving component is a crankshaft and the driven component is an eccentric shaft, in one aspect. Other engine configurations can use the embodiments disclosed herein. 
     A method for adjusting a phase between a driving component and a driven component is also disclosed herein. 
     Additional embodiments described below and in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing Summary and the following Detailed Description will be better understood when read in conjunction with the appended drawings, which illustrate a preferred embodiment of the disclosure. In the drawings: 
         FIG. 1  is a cross-sectional view of a phase adjuster according to one aspect. 
         FIG. 2  is a cross-sectional view of the phase adjuster of  FIG. 1  showing flow paths for hydraulic fluid according to one aspect. 
         FIGS. 3A and 3B  illustrate perspective views of roller-ramp assemblies according to one aspect. 
         FIG. 4  is a schematic view of a phase adjuster according to one aspect. 
     
    
    
     DETAILED DESCRIPTION 
     Certain terminology is used in the following description for convenience only and is not limiting. The words “front,” “rear,” “upper” and “lower” designate directions in the drawings to which reference is made. The words “inwardly” and “outwardly” refer to directions toward and away from the parts referenced in the drawings. “Axially” refers to a direction along the axis of a shaft. A reference to a list of items that are cited as “at least one of a, b, or c” (where a, b, and c represent the items being listed) means any single one of the items a, b, or c, or combinations thereof. This terminology includes the words specifically noted above, derivatives thereof and words of similar import. “Generally,” or “approximately” refers to +/−10% of the indicated value. 
       FIG. 4  illustrates a schematic diagram showing the arrangement of a cranktrain  200 . As used herein, the term cranktrain  200  can refer to an arrangement that generally includes a piston, a crankshaft  190 , and an eccentric shaft  180 . A phase adjuster  100 , in one aspect, is configured to adjust phasing between the crankshaft  190  and the eccentric shaft  180 , which varies the compression ratio. In general, the phase adjuster  100  is configured to continuously adjust between a high compression ratio (i.e. high efficiency, lower load) and low compression ratio (i.e. low efficiency, high load), depending on the driving conditions. One goal of a phase adjuster is to maintain the most efficient engine operating point in any driving condition, either from a fuel economy standpoint or power demand standpoint. In other words, the phase adjuster  100  is configured to change or modify a phase of the eccentric shaft  180  relative to the crankshaft  190 .  FIG. 4  is a schematic drawing and the exact positioning of components relative to each other can vary. 
     The phase adjuster  100  is operatively connected to both the crankshaft  190  and the eccentric shaft  180 . This connection or interface between the phase adjuster  100  and the crankshaft  190  and eccentric shaft  180  can be achieved in a variety of ways. Additionally, the phase adjuster  100  can be arranged between different driving components and driven components besides a crankshaft and an eccentric shaft. 
     In one aspect, the phase adjuster  100  has a gear train configured to operatively connect the crankshaft  190  to the eccentric shaft  180 . The gear train can comprise gears  1 ,  14 ,  180   a ,  190   a  which are shown in  FIG. 4  for illustrative purposes. The ratio and sizing of the gears  1 ,  14 ,  180   a ,  190   a  can vary. Other driving engagements can be provided. 
     In one embodiment, the gears  1 ,  14 ,  180   a ,  190   a  drive the eccentric shaft  180  at half the speed of the crankshaft  190 . The eccentric shaft  180  can be driven in continuous rotation at half of the crankshaft speed, in one embodiment. As described in more detail herein, hydraulic fluid or oil can be used along with mechanical springs or biasing elements to control the compression ratio. 
     In some configurations, a connecting plate can be arranged on the crankshaft  190 . In one aspect, the connecting plate is non-rotatably connected, i.e. rotationally fixed, to the crankshaft  190 . Connecting rods can also connect the eccentric shaft  180  to the crankshaft  190 , and connect an engine piston to the connecting plate. 
     One skilled in the art would understand that aspects of these components can be omitted, modified, supplemented or otherwise changed, based on the present disclosure. 
       FIG. 1  illustrates a cross-sectional view of an example embodiment of the phase adjuster  100  for the cranktrain  200 . Power enters the phase adjuster  100  through an input gear  1  from a primary mover. As used herein, the term primary mover refers to any driving component, such as the crankshaft  190 , an electric motor, or other driving input component. The input gear  1  can be configured to engage or mesh with a gear  190   a  mounted on or fixed to the crankshaft  190 . 
     The input gear  1  is connected to a drive plate  2 , which is also referred to as a roller drive plate herein. The term roller drive plate can be used to specifically refer to an embodiment which uses rollers and ramps, as described in more detail herein. However, in another aspect, the drive plate  2  does not interface or otherwise interact with rollers. 
     As shown in  FIG. 1 , this connection between the input gear  1  and the roller drive plate  2  can be achieved via at least one rivet or fastener  1   a . As used herein, the term rivet can be used to refer to any type of fastener. 
     In one aspect, the roller drive plate  2  is a stamped component. As shown in  FIG. 1 , the at least one rivet  1   a  is also connected to a support plate  18 . As shown in  FIG. 1 , an inner portion of the input gear  1  is arranged directly between the support plate  18  and the roller drive plate  2 . One skilled in the art would understand that this connection arrangement can vary. 
     The roller drive plate  2  comprises a first plurality of pockets  3  that are dimensioned to capture and support a first plurality of rollers  4 . In one aspect, the pockets  3  are formed as spiral pockets  3 . The term spiral as used in this respect also means helical, curved, or having ends that are offset or angled relative to each other. In other words, ends of the pockets  3  are displaced from each other in an axial direction and the pockets  3  are angled or curved. In one aspect, the rollers  4  are formed as cylindrical rollers. Other types of rolling elements may be used. 
     The rollers  4  are configured to be secured or supported between the roller drive plate  2  on a radially outer side, and a piston plate assembly on a radially inner side. In one aspect, the piston plate assembly includes a first piston plate  6  and a second piston plate  7 . As shown in  FIG. 1 , the piston plates  6 ,  7  are formed as stamped components and are configured to be connected or joined to each other via at least one fastener or rivet  5 . The combination of the rollers  4  and the associated pockets, as well as the associated engagement elements, such as the roller drive plate  2 , is collectively referred to herein as a first roller-ramp assembly A 1 . 
     Radially inward from the pockets  3 , the piston plate assembly  6 ,  7 , forms another set of pockets  50  which are also configured to support or capture a second set of rollers  13  along with a hub  11 . The pockets  50  are also defined as spiral pockets, in one aspect. The combination of the rollers  13  and the associated pockets  50 , as well as the associated engagement elements, such as the hub  11 , is collectively referred to herein as a second roller-ramp assembly A 2 . Additional details of the first and second roller-ramp assemblies A 1 , A 2  are disclosed herein. 
     Seals, including at least a first seal  8  and a second seal  9 , can be provided to prevent fluid communication between axial sides relative to the piston plate assembly  6 ,  7 . In one aspect, a first or radially inner seal  8  is provided on an inner diameter of the piston plate assembly  6 ,  7 , and a second or radially outer seal  9  is provided on an outer diameter of the piston plate assembly  6 ,  7 . More specifically, the radially outer seal  9  is in contact with the second piston plate  7  and the roller drive plate  2  in a radially outer region, and the radially inner seal  8  is in contact with the second piston plate  7  and the hub  11  in a radially inner region. 
     As shown in  FIG. 1 , the piston plate assembly  6 ,  7  can be axially biased with a return spring  10 . In one aspect, the return spring  10  is configured to ensure that the phase adjuster  100  starts at a predetermined compression ratio after a vehicle restart. The return spring  10  can be formed as a helical spring, or any other type of biasing element. In one aspect, the return spring  10  is arranged in a piston control chamber  34 , and contacts the support plate  18  as well. 
     The hub  11  includes a second plurality of pockets  12  and rollers  13  supported by or captured in the piston plate assembly  6 ,  7 . The pockets  12  can be formed as spiral pockets, in one aspect. In one aspect, the hub  11  is connected to the output gear  14 , and can be formed integrally with the output gear  14 . The hub is configured to transmit power out of the system from the input gear  1  based on engagement of the first and second roller-ramp assemblies A 1 , A 2 . One of ordinary skill in the art would understand that other types of actuation and engagement configurations can be used. Additionally, a single roller-ramp assembly could also be used. In one aspect, the output gear  14  meshes or engages with a gear  180   a  fixed to the eccentric shaft  180 . In another aspect, the output gear  14  is connected to another gear or any other transmission element configured to transmit power. 
     An output housing  15  is configured to enclose a portion of the phase adjuster  100  and is configured to support the hub  11 . As shown in  FIG. 1 , a first bearing  16  can be provided between the output housing  15  and the hub  11 . A first bushing  17  can be provided between the input gear  1  and the hub  11 , and more specifically can be provided between the input gear  1  and the support plate  18 . 
     In one aspect, a second bushing  19  is provided on an axial end of the hub  11  opposite from the end of the hub  11  that includes the first bushing  17 . One of ordinary skill in the art would understand that fewer or more bushings can be provided between the hub  11  and any other components. 
     A second bearing  40  can be provided between a radially outer side of the roller drive plate  2  and a radially inner surface of a valve body housing  20 . In one aspect, the valve body housing  20  and the output housing  15  are connected to each other via a fastening element or fastener  21 . Collectively, the valve body housing  20  and the output housing  15  can define an outer housing or shell of the phase adjuster  100 . In one aspect, thrust loads from the gears  1 ,  14  and rollers  4 ,  13  react through the closed loop formed through the bearings (such as bearings  16 ,  40 ) and housings (such as housings  15 ,  20 ), or through the first bushing  17 . 
     A hydraulic system or circuit is provided for the phase adjuster  100 . The hydraulic system or circuit includes multiple elements and components described herein. Generally, the hydraulic system provides hydraulic fluid to either a first side (i.e. left side or high compression ratio side) piston control chamber  34  or a second side (i.e. right side or low compression ratio side) piston control chamber  35 , as well as an outer chamber  28 . 
     As shown in  FIG. 1 , the valve body housing  20  encloses a portion of the phase adjuster  100  and contains flow passages  22  for a control hydraulic line  23  that is configured to be directed into the phase adjuster  100 . As shown in  FIG. 1 , the control hydraulic line  23  begins at a radially outer surface of the valve body housing  20 . One of ordinary skill in the art would understand that the valve body housing  20  can be directed from any area into the valve body housing  20 . 
     A control valve  24  controls the flow and pressure of the flow passages  22 . In one aspect, the control valve  24  is a solenoid valve that is configured to fill a spool piston control chamber  25  partially defined by a spool valve  26 . Fluid is configured to exit the spool piston control chamber  25  through a restricted flow path or leakage gap  27 . Fluid from this flowpath is directed into the outer chamber  28 . 
     The spool valve  26  is arranged within the output hub  11  in one aspect. The spool valve  26  seals with the output hub  11  with tight clearances  29  arranged between a radially outer surface of the spool valve  26  and a radially inner surface of the output hub  11 . 
     In one aspect, a back plate  30  can be provided on an axially end of the phase adjuster  100 . The back plate  30  can be connected to the valve body housing  20  via a fastener  31 , which aids in the assembly of the spool valve  26  with the hub  11  and the valve body housing  20 . In one aspect, the spool valve  26  is axially biased to one side with a spool spring  32 , which is arranged between the spool valve  26  and the back plate  30 . 
     An end of the spool valve  26  has a piston apply pressure port  33  that is configured to supply fluid to either the first side (i.e. left side or high compression ratio side) piston control chamber  34  or the second side (i.e. right side or low compression ratio side) piston control chamber  35 . The two chambers  34 ,  35  are generally separated by the piston plate assembly  6 ,  7 . 
     In one aspect, a radial inner boundary of at least one of the first piston control chamber  34  or the second piston control chamber  35  is defined by the hub  11  which is connected or formed with the output gear  14 . As shown in  FIG. 1 , the hub  11  can define the radial inner boundary of both of the piston control chamber  34  and the second piston control chamber  35 . As shown in  FIG. 1 , a radial outer boundary and at least one axial outer boundary is defined by the input gear assembly, i.e. the input gear  1 , the support plate  18 , or the drive plate  2 . The piston plates  6 ,  7 , define an axial inner boundary of a respective one of the first piston control chamber  34  and the second piston control chamber  35 . 
     In one aspect, the piston apply pressure port  33  is defined on a first axial side of the phase adjuster assembly and the control hydraulic line  23  is defined on a second, opposite axial side of the phase adjuster assembly. One of skill in the art would understand that the configuration for the piston apply pressure port  33  and the control hydraulic line  23  can vary. 
     In one aspect, fluid flow is directed into the piston control chambers  34 ,  35  through a first and second apply port  36 ,  37  in the hub  11  and drained or released through a first and second release port  38 ,  39 . In one aspect, the ports  36 - 39  are formed as cross-drilled openings. The relative openings of the apply ports  36 ,  37  and release ports  38 ,  39  are controlled by hydraulically moving the spool valve  26  axially left or right via the control valve  24 . In one aspect, movement of the spool valve is controlled via pulse-width modulation. In other words, a position of the spool valve  26  is proportional to the current in the control valve  24 , which may be a solenoid. 
     If a specific one of the apply ports  36 ,  37  is 100% or completely open, then its corresponding release port  38 ,  39  is 100% or completely closed, and vice versa for both piston control chambers  34 ,  35 . Any axial position in between can also be achieved, such that the amount of fluid provided to the piston control chambers  34 ,  35  is completely variable. The first and second release port  38 ,  39  are shown in dashed lines in  FIG. 1  for illustrative purposes. 
     Leakage is permitted out of the piston control chambers  34 ,  35  through the first and second bushings  17 ,  19  if fluid pressure is kept to a low enough amount to maintain pressure. Any leakage through the first and second bushings  17 ,  19  combines with the control flow drainage in the outer chamber  28  and passes through the bearing  16  and the gears  1 ,  14  to keep these components lubricated before exiting the phase adjuster  100 . Control of the fluid flow could also be facilitated or managed by holes or openings arranged in the housings, such as elements  15 ,  20 , for the gears  1 ,  14 . 
       FIG. 2  illustrates some exemplary flow paths through the phase adjuster  100 . As shown in  FIG. 2 , a first flowpath P 1  is provided through the piston apply pressure port  33 . This first flowpath P 1  is directed to the piston control chambers  34 ,  35  in a specific manner depending on the arrangement of the spool valve  26 . As shown in  FIG. 2 , the first apply port  36  is opened while the second apply port  37  is closed. Dashed lines are shown in  FIG. 2  for illustrative purposes only to show a blocked flowpath associated with P 1  to the second apply port  37 . 
     From the piston control chambers  34 ,  35 , second flowpaths P 2  are provided as leakage flowpaths that are directed out of the piston control chambers  34 ,  35  via a respective one of the bushings  17 ,  19 . Once the fluid is directed into the outer chamber  28 , a third flowpath P 3  is provided that is directed out of the outer chamber  28  and out of the phase adjuster  100 . These third flowpaths P 3  can be defined through first bearing  16 , or via additional drainage holes or openings in other components, such as the housing  15 . The drainage holes are illustrated as openings  15   a ,  15   b  in  FIG. 2 . A fourth flowpath P 4  or control flowpath is also shown in  FIG. 2 . This flowpath P 4  generally directs fluid into the flow passages  22 , and is ultimately used to control the spool valve  26 . 
     While exemplary flowpaths are illustrated in  FIG. 2 , one of ordinary skill in the art would understand that the flowpaths can vary. Generally, hydraulic fluid is provided to the assembly in order to selectively pressurize one of the piston control chambers  34 ,  35 . The fluid is also used to lubricate components of the assembly. 
     During engine or vehicle startup, there is no pressure through the phase adjuster  100 , therefore, the return spring  10  holds the piston plate assembly  6 ,  7  in a maximum compression ratio position until the first piston plate  6  abuts with the roller drive plate  2 . While in this position, the spool spring  32  keeps the spool valve  26  in an axially leftmost position. 
     Once engine oil pressure is established, the left-side piston area  34  is charged or filled with hydraulic pressure, thus keeping the piston plate assembly  6 ,  7  in the maximum compression ratio position initially. After startup, the position of the piston plate assembly  6 ,  7  can be adjusted by changing the pressure in the spool piston control chamber  25  with the control valve  24 . This moves the spool valve  26  back and forth in an axial direction, thus opening and closing the first and second apply ports  36 ,  37  and the first and second release ports  38 ,  39  variably and proportionally. 
     Pressure differential is then established between left side and right side piston control chambers  34 ,  35 , and the piston plate assembly  6 ,  7  starts to travel axially if the differential is not zero. When the piston plate assembly  6 ,  7  moves in an axial direction, the pressure force acts on the spiral ramps through the rollers  4 ,  13 . This creates a tangential force which also rotates the piston plate assembly  6 ,  7  and therefore rotates the hub  11  relative to the roller drive plate  2 , thus achieving the phase adjustment of the output gear  14  relative to the input gear  1 . One of ordinary skill in the art would recognize that the hydraulic pressure is used to bias motion in one direction or another, but it is not the primary phasing force in the system. Instead, the crankshaft torsionals are the primary phasing force, and are balanced against the spring force at a given axial position. 
     In one aspect, the phase adjuster  100  disclosed herein provides the ability to adjust the compression ratio based on a hydraulic assist mode or function. In one aspect, the hydraulic assist mode or function is implemented via the roller-ramp assemblies A 1 , A 2 . One skilled in the art would understand that other configurations could be used that do not require rollers and ramps. 
     The phase adjuster  100  disclosed herein can be adapted to be used in any type of cranktrain or any configuration including a driving and driven element. For example, the phase adjuster  100  can be implemented or realized in a configuration in which an eccentric shaft is driven directly by a crankshaft. In another example, the phase adjuster  100  can be adapted to be used in a configuration in which an eccentric shaft is driven by a separate electric motor and is not directly connected to the crankshaft. 
       FIGS. 3A and 3B  illustrate additional aspects of roller-ramp assemblies A 1 , A 2 , and more specifically illustrates specific details of the rollers  4 ,  13  relative to the roller drive plate  2  and the hub  11 . As shown in  FIG. 3A , the roller drive plate  2  defines spiral pockets  2   a ,  2   b . As shown in  FIG. 3B , the hub  11  also defines spiral pockets  11   a ,  11   b . In one aspect, movement of the roller drive plate  2  in a first axial direction associated with a first set of rollers  4   a  and a first set of spiral pockets  2   a  causes rotation of the hub  11  in a first rotational direction via a first set of rollers  13   a  engaged a first set of spiral pockets  11   a . Similarly, movement of the roller drive plate  2  in a second axial direction associated with a second set of rollers  4   b  and a second set of spiral pockets  2   b  causes rotation of the hub  11  in a second rotational direction via a second set of rollers  13   b  engaged with a second set of spiral pockets  11   b . In other words, a first group of rollers  4   a ,  13   a  and spiral pockets  2   a ,  11   a  facilitate movement of the piston plate assembly  6 ,  7 , in a first axial direction which yields rotation of the hub  11  in a first rotational direction causing the output gear  14  to be phased relative to the input gear  1  in the first rotational direction. A second group of rollers  4   b ,  13   b  and spiral pockets  2   b ,  11   b  facilitate movement of the piston plate assembly  6 ,  7  in a second axial direction which yields rotation of the hub  11  in a second rotational direction causing the output gear  14  to be phased relative to the input gear  1  in the second rotational direction. 
     Torque transmitted through the rollers  4 ,  4   a ,  4   b ,  13 ,  13   a ,  13   b  creates an axial force due to the ramp geometry, which acts against the fluid pressure in the piston control chambers  34 ,  35 . The pressure may need to be adjusted to compensate for the input torque and keep the phase angle at the desired or predetermined value. The pressure is controlled to either allow flow into or out of the chambers  34 ,  35 , depending on whether movement of the piston is desired or not. 
     Although the roller-ramp assemblies A 1 , A 2  are illustrated with specific features in the drawings, one of ordinary skill in the art would understand that the exact configuration of these assemblies can vary. Generally, the phase adjuster  100  provides a configuration in which the piston plate assembly  6 ,  7  is driven in an axial direction via a hydraulic fluid circuit or system (i.e. at least elements  20 ,  22 ,  23 ,  25 ,  26 ,  27 , etc.) to phase or adjust a position of the output gear  14  relative to the input gear  1  to transmit power out of the phase adjuster  100 . 
     A method for adjusting the phase between a driving component  190  and a driven component  180  is also disclosed herein. The method includes engaging an input gear  1  with the driving component  190  and engaging an output gear  14  with the driven component  180 . The method includes arranging a piston plate assembly  6 ,  7  operatively between the input gear  1  and the output gear  14  such that axial displacement of the piston plate assembly  6 ,  7  adjusts a phase between the driving component  190  and the driven component  180 . The method includes connecting a hydraulic fluid system to control a first piston control chamber  34  on a first axial side of the piston plate assembly  6 ,  7 , and a second piston control chamber  35  on a second axial side of the piston plate assembly  6 ,  7 . The method includes selectively supplying or releasing hydraulic fluid pressure to at least one of the first piston control chamber  34  or the second piston control chamber  35  such that the piston plate assembly  6 ,  7  is displaced to adjust the phase between the driving component  190  and the driven component  180 . Additional method steps can be included that implement other functional aspects or configurations described herein. 
     In one aspect, a phase adjuster assembly  100  is provided that includes an input gear  1  configured to be driven by the driving component and an output gear  14 . A phase adjuster is connected to the input gear  1  and the output gear  14 , and is configured to be hydraulically actuated to adjust a phase between the driving component and the driven component. The phase adjuster can include a piston plate assembly and a hydraulic fluid system or circuit. The input gear  1 , the output gear  14 , and the phase adjuster are arranged inside a common housing. As shown in  FIG. 1 , the common housing can be formed from a plurality of plates, such as the output housing  15  and the valve body housing  20 . 
     The phase adjuster disclosed herein is completely variable. In other words, the phase adjuster is configured to adjust the phase between the driven element and the driving element according to multiple compression ratios. In one aspect, axial movement of at least one component of a piston plate assembly, along with oscillating crankshaft torque, facilitate phasing between the input gear and the output gear in incremental and variable steps. 
     While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments that may not be explicitly described or illustrated. 
     While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, to the extent any embodiments are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics, these embodiments are not outside the scope of the disclosure and can be desirable for particular applications. 
     Having thus described the present embodiments in detail, it is to be appreciated and will be apparent to those skilled in the art that many physical changes, only a few of which are exemplified in the detailed description of the disclosure, could be made without altering the inventive concepts and principles embodied therein. 
     It is also to be appreciated that numerous embodiments incorporating only part of the preferred embodiment are possible which do not alter, with respect to those parts, the inventive concepts and principles embodied therein. 
     The present embodiment and optional configurations are therefore to be considered in all respects as exemplary and/or illustrative and not restrictive, the scope of the disclosure being indicated by the appended claims rather than by the foregoing description, and all alternate embodiments and changes to this embodiment which come within the meaning and range of equivalency of said claims are therefore to be embraced therein. 
     LOG OF REFERENCE NUMERALS 
     
         
         input gear  1   
         fastener  1   a    
         roller drive plate  2   
         pockets  2   a ,  2   b    
         pockets  3   
         rollers  4   
         rollers  4   a ,  4   b    
         fastener  5   
         first piston plate  6   
         second piston plate  7   
         first seal  8   
         second seal  9   
         return spring  10   
         hub  11   
         pockets  11   a ,  11   b    
         pockets  12   
         rollers  13   
         rollers  13   a ,  13   b    
         output gear  14   
         output housing  15   
         openings  15   a ,  15   b    
         first bearing  16   
         first bushing  17   
         support plate  18   
         second bushing  19   
         valve body housing  20   
         fastening element  21   
         flow passages  22   
         control hydraulic line  23   
         control valve  24   
         spool piston control chamber  25   
         spool valve  26   
         clearance  27   
         outer chamber  28   
         clearance  29   
         back plate  30   
         fastener  31   
         spool spring  32   
         piston apply pressure port  33   
         piston control chambers  34 ,  35   
         apply ports  36 ,  37   
         release ports  38 ,  39   
         second bearing  40   
         pockets  50   
         phase adjuster  100   
         eccentric shaft  180   
         gear  180   a    
         crankshaft  190   
         gear  190   a    
         cranktrain  200