Patent Publication Number: US-2021172345-A1

Title: Actuator for cam phaser and cam phaser

Description:
RELATED APPLICATIONS 
     This application is a continuation in part of U.S. patent application Ser. No. 16/011,997 filed on Jun. 19, 2018 which is a non-provisional of U.S. provisional patent application 62/522,624 filed on Jun. 20, 2017, both of which are incorporated in their entirety by this reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to an actuator for a cam phaser and to a cam phaser, 
     BACKGROUND OF THE INVENTION 
     Cam phasers for internal combustion engines are well known. The cam phaser includes a hydraulic valve with a piston that is axially move able in a housing of the hydraulic valve and which controls a hydraulic loading of the cam phaser. controlling the cam phaser is typically done hydraulically by positioning the piston and releasing or closing connections provided at the housing. The piston is positioned by an electromagnetic actuator. Function specific components of the actuator like in particular a plunger for moving the piston and components for generating a magnetic field for moving the plunger are received in a housing of the actuator. Typically the housing is specific to an internal combustion engine and configured to be received at a housing section of the internal combustion engine so that a plurality of housings have to be produced in order to facilitate safe fixing of the actuator at a housing section that is typically associated with the internal combustion engine. 
     Thus the publication document DE 10 2013 013 659 A1 discloses a connection of an actuator with a housing section wherein a support element is configured to establish the connection wherein the retaining element includes support elements and wherein the retaining element is arranged between a actuator cover and the housing section. Since the retaining element is received with its support elements between a housing cover of the actuator and the housing section, the housing section requires a recess that is configured specifically for the retaining element so that a safe connection is facilitated between the housing and the housing section. This causes a comprehensive and thus a complex and comprehensive of the housing section to the retaining element. 
     BRIEF SUMMARY OF THE INVENTION 
     Thus, it is an object of the invention to provide an actuator for a cam phaser which is attach able in a modular manner reliably and at low cost. It is another object of the invention to provide a cam phaser that implements a reliable adjustment of the cam shaft. 
     The object is achieved according to the invention by an actuator for a cam phaser, the cam phaser including a hydraulic valve that is adjustable by the actuator, wherein the actuator is receivable at a housing section of a component that receives the cam phaser, wherein the actuator includes a retaining element and a housing with functionally relevant components, wherein the actuator is attached by the retaining element at the housing section, wherein the retaining element is configured separate from the housing, wherein safe positioning of the actuator at the housing section is provided by a section of the retaining element that supports the actuator at the housing section in a direction of an axial orientation of the actuator, and wherein a housing cover of the housing is at least partially arranged between the section of the retaining element and the housing section. 
     The object is also achieved by a cam phaser including the electromagnetic actuator described supra. 
     Advantageous embodiments with useful and nontrivial improvements of the invention according to the invention are provided in the respective dependent claims. 
     An actuator according to the invention for a cam phaser is configured receivable at a housing section of a unit receiving the cam phaser. The cam phaser includes a hydraulic valve which is adjustable by the actuator. The actuator includes a retaining element to attach the actuator at the housing section, wherein the retaining element is configured separate from the actuator. According to the invention a section of the retaining element is formed that supports the actuator in a direction of its axial extension at the housing section in order to reliably position the actuator at the housing section, wherein a housing cover of the actuator is at least partially arranged between the section of the retaining element and the housing section. This means that the actuator is supported by the retaining element at the housing section wherein a longitudinal axial position of the actuator is secured in particular. This means put differently that a functionally relevant section of the actuator which includes in particular an adjustment device for adjusting the piston and movement devices configured to cause a movement of the adjustment device, e.g. configured as a magnet arrangement and an electrically flow able coil configured to generate a magnetic field can be produced separate from the retaining element that has to be configured housing specific, wherein the housing specific actuator is provided as a combination of both components. Put differently the actuator is configured modular since the functionally relevant section can be produced separately from an attachment relevant section of the actuator. 
     It is an advantage that the retaining element is configured housing specific wherein however the functionally relevant section of the actuator which is enveloped by the housing cover does not have to be configured to provide fixing attachment at the housing section. 
     Thus the functionally relevant section of the actuator can be produced in high numbers since it is independent from the housing section and the retaining element fixing the functionally relevant section of the actuator of the housing section can be produced in a smaller number specific to the housing section. 
     Thus a secure housing section specific connection is implemented wherein the functionally relevant section of the actuator can be produced in high volume and thus in a cost effective manner so that the entire modular actuator, the functionally relevant section and the retaining element, can be produced overall in a cost effective manner. 
     The modular configuration has the additional advantage of flexible assembly which facilitates for example a quick attachment of the retaining element to proto types or production components. 
     The retaining element is configured for fixation at the housing section and can thus include receiving openings configured to receive fixing elements, e.g. bolts. By the same token it can include fixing devices in the form of snap elements or it can be fixed by rotary form locking, e.g. by a bayonet closure at the housing section. 
     Secure joining of the functionally relevant section and the retaining element can be provided in that the housing cover and the retaining element are configured in an alternating manner as an outer boundary that is oriented away from the housing section. 
     Thus a support of the housing cover and of the retaining element is implemented in an alternating manner relative to the housing section wherein the retaining element as well as the housing cover and thus the housing support each other in an alternating manner. 
     In another embodiment of the actuator according to the invention the retaining element is configured at least partially complementary to the housing which yields another safe reception of the retaining element at the housing cover and vice versa. 
     In another embodiment of the actuator according to the invention the retaining element is configured so that it envelops the housing essentially over its circumference, in particular over its enveloping surface. This has the advantage that the actuator is flat in an axial direction of the actuator longitudinal axis so that the actuator is characterized by small installation space requirement. 
     Advantageously the retaining element receives the actuator through form locking in order to reliably attach the actuator at the housing section. 
     In another embodiment of the actuator according to the invention a snap locking element is configured at the housing cover, advantageously at an enveloping surface of the housing so that a movement of the retaining element in the axial direction is preventable. The snap locking element provides a safe connection between the functionally relevant section of the actuator and the retaining element so that a functionally relevant section and the retaining element configured as a component can be captured and positioned during an installation of the actuator at the housing section. In another embodiment the retaining element is configured to receive a position element configured at the housing which facilitates a correct positioning of the retaining element about the housing circumference. This in turn facilitates a correct positioning of the actuator at the housing section. 
     The positioning element is advantageously configured as a plug in device, in particular its connection socket since the plug in device is provided for supplying energy to the actuator and respective electrical current conducting elements are provided at the housing section wherein the electrically conducting elements are to be conducted by the plug in device. This means put differently that the positioning element is configured to correctly position the actuator at the housing section with respect to a circumference of the actuator. The position safety can also be implemented in that the retaining element includes an electrical connection of the plug in device. 
     The retaining element is produced in a cost effective manner by an injection molding method, in particular from a plastic material, 
     The retaining element can be configured as a component that completely covers the housing cover however it is sufficient for reliable and safe reception of the functionally relevant section to configure the retaining element frame shaped, wherein weight savings are provided in addition to a reduced material requirement that cuts costs. 
     Advantageously the housing section is a section of the internal combustion engine, in particular of a cylinder head of the internal combustion engine since short distances between the actuator and the cam shaft to be adjusted can be provided which reduces reaction time and thus adjustment time, 
     A second aspect of the invention relates to a cam phaser with an electromagnetic actuator. According to the invention the actuator is configured as described supra. Thus, a reliable cam phaser can be implemented which provides a reliable adjustment of valve timing of the internal combustion engine which includes the cam phaser according to the invention. Since adjustment of valve timing influences fuel burn and thus emissions of the internal combustion engine a fuel burn and emissions reduced reliable internal combustion engine can be provided. 
    
    
     
       BRIEF DESCRPTION OF THE DRAWINGS 
       Other advantages features and details of the invention can be derived from the subsequent description of advantageous embodiments and from the drawing figures. The feature and feature combinations recited in the preceding description and the feature and feature combinations recited in the subsequent figure description and/or in the figures by themselves are not only useable in the respectively stated combination but also in other combinations or by themselves without departing from the spirit and scope of the invention. Identical reference numerals are associated with identical or functionally equivalent elements. For reasons of clarity it is possible that the elements are not provided with their reference numeral in all figures without however losing their association, wherein; 
         FIG. 1  illustrates an actuator according to the invention in a first embodiment; 
         FIG. 2  illustrates the actuator according to  FIG. 1  in a perceptively view; 
         FIG. 3  illustrates an actuator according to  FIG. 1  in a sectional view; 
         FIG. 4  illustrates the actuator according to  FIG. 1  with a retaining element in a perspective view from below; 
         FIG. 5  illustrates the actuator according to  FIG. 4  in a side view; 
         FIG. 6  illustrates the actuator according to  FIG. 4  in a top view; 
         FIG. 7  illustrates a perspective top view of the retaining element according to the first embodiment; 
         FIG. 8  illustrates a sectional detail view VIII of the actuator with the retaining element according to  FIG. 4 ; 
         FIG. 9  illustrates a top view of the actuator according to the invention with the retaining element in a second embodiment; 
         FIG. 10  illustrates a perspective top view of the actuator with the retaining element according to  FIG. 9 ; 
         FIG. 11  illustrates a perspective bottom view of the actuator according to  FIG. 9 . 
         FIG. 12  illustrates a top view of the retaining element according to the second embodiment; 
         FIG. 13  illustrates a side view of the retaining element according to  FIG. 12   
         FIG. 14  illustrates a perspective top view of a detail XIV of the actuator according to  FIG. 9 ; 
         FIG. 15  illustrates a top view of the actuator according to the invention in a third embodiment; 
         FIG. 16  illustrates a side view of the actuator according to  FIG. 15 ; 
         FIG. 17  illustrates a perspective top view of the actuator with its retaining element in a fourth embodiment; 
         FIG. 18  illustrates a perspective top view of the actuator according to the invention in a fifth embodiment; 
         FIG. 19  illustrates a side view of the actuator according to  FIG. 18 ; 
         FIG. 20  illustrates a perspective top view of the retaining element of the actuator according to  FIG. 18 ; 
         FIG. 21  illustrates a perspective view from below of the retaining element according to  FIG. 20 ; and 
         FIG. 22  illustrates a side view of the retaining element according to  FIG. 20 . 
     
    
    
     DETAILED DESCRPTION OF THE INVENTION 
     A cam phaser that is not illustrated in detail is configured to adjust a cam shaft. The cam phaser includes a hydraulic valve that is not illustrated in more detail which includes a piston that is not illustrated in more detail and which is moveable in particular in an axial direction. In order to hydraulically supply the cam phaser plural connections are provided at a housing of the hydraulic valve that receives the piston. The housing is configured substantially tubular. 
     The cam phaser facilitates adjusting opening and closing timing of gas control valves of an internal combustion engine that includes a cylinder head and which is not illustrated in more detail during operations. 
     Thus a relative angular orientation of a cam shaft that is rotate ably received in the cylinder head of the internal combustion engine and not illustrated in more detail is continuously adjusted relative to a crank shaft of the internal combustion engine that is not illustrated in more detail wherein the cam shaft is rotated relative to the crank shaft. Rotating the cam shaft moves the opening and closing timing of the gas control valves so that the internal combustion engine can develop optimum power at a respective speed. 
     A stator of the cam phaser is connected torque proof with a drive gear of the cam shaft. Insides of a stator base element include radially inward extending bars in uniform distances so that an intermediary space is formed between two respective adjacent bars. A vane of a rotor hub of a rotor of the cam phaser is arranged so that it protrudes into the intermediary space. Corresponding to the number of intermediary spaces the rotor hub includes a plurality of veins. Thus the veins divide each intermediary space into pressure cavities. A pressure medium, typically a hydraulic fluid is introduced into the intermediary spaces by the hydraulic valve in a controlled manner. 
     A pressure cavity is associated with each operating connection. Thus the first pressure cavity is associated with the first operating connection and the second pressure cavity is associated with the second operating connection. In order to adjust an angular orientation between the cam shaft and the crank shaft the pressure medium in the first pressure cavity or in the second pressure cavity is pressurized while the second pressure cavity or the first pressure cavity is unloaded. The unloading is performed through at least one tank connection, wherein the hydraulic fluid can drain through the tank connection. 
     The piston is moved by an actuator  10  which is configured in a first embodiment according to  FIGS. 1-8 , wherein a move able plunger  12  of the actuator  10  c.f e.g.  FIG. 11  is axially move able along a longitudinal axis  14  of the actuator  10 . The actuator  10  is configured as an electromagnetic actuator. The actuator  10  includes a pole tube  24  that is arranged within a cylindrical coil that generates a magnetic field and a housing  16 . The housing  16  produced according to a plastic injection molding method so that it is possible in a cost effective manner to fabricate the housing  16  and to simultaneously insert various components of a pole yoke which provides closed magnetic flux during the injection molding method. 
     In order to provide the magnetic flux the coil is loadable with power through a connection socket  18  that is received at the housing  16 . 
     The actuator  10  is configured as a preassembled unit for attachment at a housing section  71 . In the illustrated embodiments the actuator  10  is configured for attachment at a housing section  71  of a cylinder head. This means put differently that the actuator  10  is attached at the cylinder head. By the same token the housing section can also be a partial section of the cam phaser or another component of the internal combustion engine, 
     In order to provide a reliable connection of the actuator  10  with the housing section the housing section includes a retaining element  20  that is independent from its function specific section wherein the retaining section is used for moving the piston and is at least partially enveloped by the housing  16  wherein the retaining element supports the function specific section in a direction of its axial extension against the housing section. 
     The housing includes a housing functional section  15  and a housing cover  26 . The housing  16  includes a coil that is not illustrated in more detail which is received in a coil carrier  22 . The coil carrier  22  includes a pole tube  24  which is arranged between a housing cover  26  of the housing  16  and the coil carrier  22 . A connection  28  configured to supply electrical current to the coil is received in the connection socket  18  which extends at least in sections over a cover surface of the housing cover  26 . 
     The housing cover  26  includes a cover ring  32  which radially envelops a pot shaped cover section  34 . The cover ring  32  functions as a stop of the preassembled actuator  10  during assembly at the housing section. 
       FIG. 3  illustrates the actuator housing functional section  15  and the actuator housing cover  26  being fixed at each other through direct bidirectional axial and radial form locking between the actuator housing functional section  15  and the actuator housing cover  26 . The radial form locking is provided at a cylindrical outer enveloping surface of the actuator housing cover  25  and a cylindrical inner surface of the actuator housing functional section. The axial form locking is provided between a recess  27  in the cylindrical outer enveloping surface of the actuator housing cover  26  and inward curved protrusion  25  of the actuator housing functional section  15  that locks into the recess  27  of the actuator housing cover  26  as evident from  FIG. 3 . 
       FIG. 4  illustrates the actuator  10  according to the invention in the first embodiment assembled with its retaining element  20 . The retaining element  20  which is illustrated by itself in  FIG. 7  is frame shaped and includes an opening  36  that is configured complementary to an enveloping surface section  38  of the cover section  34 . This means put differently that the cover element  20  is configured at least partially complementary with the housing  16 . 
     In order to fix the actuator  10  at the housing section the actuator is positioned in a receiving opening that is provided in the housing section, wherein the cover ring  32  advantageously contacts the housing section with its first annular surface  40  that is oriented towards the housing section. Subsequently the retaining element  20  is placed onto the housing  16  wherein the cover section  34  is arranged in the opening  36 . In order to secure the retaining element  20  at the housing  16  a snap locking element  42  is configured at the enveloping surface section  38  of the cover section  34  wherein the snap locking element is configured to prevent a movement of the support element  20  in the axial direction after fixing the retaining element  20  at the housing section since the retaining element  20  is arranged in the portion of the snap locking element  42  quasi between the housing section and the housing  16 . Advantageously two snap locking elements  42  are configured that are positioned opposite to each other. 
     Thus, the housing cover  26  and the retaining element  20  are configured in an alternating manner over a circumference of the actuator  10  as an outer border that is oriented away from the housing section. This means put differently that a cover surface  44  defining the actuator  10  with its retaining element  20  relative to the ambient wherein the cover surface  44  is configured transversal to the longitudinal axis  14  is configured in an alternating manner by the housing cover  26  and the retaining element  20 . 
     Another option to fix the actuator  10  at the housing section is to position the function specific section of the actuator  10  in a first step without the retaining element  20  in a predetermined receiving opening in the housing section. In order to fixate the actuator  10  at the housing section the retaining element  20  is subsequently applied to the housing  16  starting from the cover surface  30 , wherein the cover section  34  is arranged in the opening  36 . A second annular surface  53  of the covering  32  is arranged opposite to the first contact surface  54  and contacts the contact surface  54  at least partially. The snap locking element  42  fixates the retaining element  20  at the housing  16  and thereafter the retaining element  20  is fixated at the housing section. 
     Thus the retaining element  20  is configured to envelop the housing  16 , in particular the housing cover  26  along its circumference in particular along its enveloping surface. 
     In order to receive the connection socket  18  the retaining element  20  includes a recess  46  that is unlimited on one side and configured transversal in particular perpendicular to the opening  36  wherein the recess  46  supports the connection socket  18  with three of its lateral surfaces  48 . This means put differently that the retaining element  20  is configured to receive a plug in device  52  of the actuator  10  which includes the connection socket  18  and the connection  28 . 
     In an embodiment that is not illustrated in more detail the two side surfaces  48  that are configured opposite to each other are provided with clamping elements protruding into the recess at edges  50  so that an additional retaining safety of the retaining element  20  is provided at the housing  16  in addition to the snap locking elements  42  before and during the assembly of the actuator  10  at the housing section. 
     The retaining element  20  is configured as an injection molded component in order to save weight and cost it is configured frame shaped and includes recesses  56  which have a rather small wall thickness wherein struts  58  are configured between the recesses  56  in order to provide stability and strength to the retaining element  20  wherein a wall thickness of the retaining element  20  is increased at portions including the struts  58  compared to the wall thickness of the recesses  56 . 
     In order to attach the actuator  10  at the housing section receiving openings  60  are provided to receive attachment devices that are not illustrated in more detail which are configured to provide a fixing attachment of the actuator  10  at the housing section. The attachment devices can be provided in the form of bolts so that a disengage able connection of the actuator  10  with the housing section is provided. If the retaining element  20  is provided as a low cost plastic component as it is the case in the instant embodiment metal sleeves  62  are arranged in the receiving opening  60  so that a secure connection can be established. In the illustrated embodiment four receiving openings are provided. More or fewer receiving openings can be arranged wherein the number of the receiving openings  60  is configured to provide safe support of the actuator  10  at the housing section. Not every receiving opening  60  has to be used for attachment purposes. This can be handled in a flexible manner and can be adapted to the housing section. 
       FIG. 8  illustrates the actuator  10  with its retaining element  20  in a detail view VIII in cross section. The first contact surface  54  is arranged opposite to the second ring surface  53  and in contact therewith wherein the second contact surface  55  of the retaining element  20  is configured at a distance a from the first contact surface  54 . Advantageously the distance A corresponds to a thickness D of the cover ring  32  so that a flat contact of the actuator  10  can be configured between the housing section and the actuator  10  and advantageously a seal element can be arranged between the housing section and the actuator  10 . 
       FIGS. 9-14  illustrate the actuator  10  according to the invention in a second embodiment. The retaining element  20  is configured substantially identical to the retaining element  20  according to the first embodiment wherein the most significant distance is the reception or envelopment of the connection socket  18 . Compared to the first embodiment of the actuator  10  according to the invention wherein the retaining element  20  is configured to substantially envelop the connection socket  18  in the circumferential direction. The retaining socket  18  of the second embodiment is supported in a radial direction of the actuator  10 . This means put differently that an element section  64  of the retaining element  20  configured to receive the connection socket  18  extends in axial direction in circumferential direction and in radial direction. 
     The connection socket  18  includes a boss shaped lug  70  at its end  68  that is arranged in a portion of the actuator center  66 , wherein the boss shaped lug is received and supported in the element section  64 . The lug  70  can have different shapes. In the illustrated second embodiment the lug includes a rectangular cross section. By the same token the lug could also have a circular or oval or another cross section. Accordingly the lug  46  is configured complementary to the cross section. 
     It is appreciated that the reception of the connection socket  18  or of the plug in device  52  in the retaining element  20  provides secure positioning of the actuator  10  at the housing section. This means put differently that a position of the actuator  10  relative to the housing section can be safely provided by a positioning element that is configured at the housing  16  or at the retaining ring  20  wherein the positioning element in the instant embodiment is the connection socket  18  or the plug in device  52 . 
     In  FIGS. 15 and 16  the actuator  10  according to the invention is illustrated in a third embodiment. The connection socket  18  is configured in the portion of the lug  70  differently from the connection socket  18  of the second embodiment, wherein the lug  70  is configured without distance between the cover surface  30 . Thus as a protrusion in a direction of the longitudinal axis  14 . 
     In  FIGS. 17-22  which illustrate a fourth embodiment of the actuator  10  according to the invention the connection socket  18  is enveloped by the retaining element  20 . Put differently this means that the connection socket  18  is configured integrally in one piece together with the retaining element  20 . Thus the retaining element  20  includes an electrical connection of the plug in device  52 . In order to supply energy and to correctly position the actuator  10  at the housing section the connection  28  of the plug in device  52  is configured at the cover surface  30 . When assembling the actuator  10  joining the connection with a connection plug that is not illustrated in more detail and which is configured complementary to the connection  28  and which is arranged in the connection socket  18  configured at the support element  20  the connection of the retaining element  20  at the housing  16  is stabilized in addition to the snap lock connection implemented by the snap locking elements  42 . 
     Through the retaining element  20  the actuator  10  can be attached at the housing section easily and can be disengaged from the housing section in a simple manner. Furthermore a seal element that is not illustrated in more detail is arranged between the retaining element  20  and the housing section. In the illustrated embodiment the actuator  10  is attached at the housing section through a threaded connection. By the same token the retaining element  20  can include devices for establishing a snap locked connection and/or a rotary connection, in particular a bayonet connection instead of the receiving opening  60 . 
     REFERENCE NUMERALS AND DESIGNATIONS 
       10  actuator 
       12  plunger 
       14  longitudinal axis 
       15  housing functional section 
       16  housing 
       18  connection socket 
       20  retaining element 
       22  coil carrier 
       24  pole tube 
       25  protrusion 
       26  housing cover 
       27  recess 
       28  connection 
       30  cover surface 
       32  cover ring 
       34  cover section 
       36  opening 
       38  enveloping surface section 
       39  enveloping surface 
       40  first annular surface 
       42  snap locking element 
       44  cover surface 
       46  recess 
       48  lateral surface 
       50  edge 
       52  insertion device 
       53  second annular surface 
       54  first contact surface 
       55  second contact surface 
       56  recess 
       58  strut 
       60  receiving opening 
       62  metal sleeve 
       64  element section 
       66  actuator center 
       68  end 
       70  lug 
       71  housing section 
     A distance 
     D thickness