Abstract:
A cam carrier assembly may include at least a cam carrier mounted on a cylinder head and including a support, an actuator shaft, a portion of which is mounted in the support and rotatable to control a valve life, and a cap mounted on the cylinder head and coupled to the at least a cam carrier to rotatably support the portion of the actuator shaft and surrounding and rotatably supporting the other portion of the actuator shaft, which is not surrounded by the support.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to Korean Patent Application Number 10-2009-0053439 filed on Jun. 16, 2009 the entire contents of which application are incorporated herein for all purposes by this reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a cam carrier assembly and, more particularly, to a cam carrier assembly capable of stably supporting an actuator shaft while defining therein a novel oil circuit. 
     2. Description of Related Art 
     In a four-stroke gasoline engine, intake and exhaust valves generally serve to control intake into and exhaustion from a cylinder while hermetically sealing the cylinder. Specifically, the intake valve opens in intake stroke to thereby draw a fuel-air mixture into the cylinder, and the exhaust valve opens in exhaust stroke to thereby expel any remaining combustion gas out of the cylinder. In contrast, in compression and power strokes, both the intake and exhaust valves close to thereby hermetically seal the cylinder. 
     Valve types are divided into, for example, side valve (SV), overhead valve (OHV), and overhead camshaft (OHC) types according to the positions of cam shafts and valves. Among the OHC types, the double overhead camshaft (DOHC) type, with camshafts each dedicated to either an intake or exhaust valve, is generally used in vehicle engines. 
     The opening/closing of the valve is enabled when a cam on a camshaft pushes one end of the valve with a rocker arm. The camshaft is rotated by a driving force from a crank shaft, transmitted by, for example, a timing chain or a timing belt. A key factor determining the hermetic sealing, the amount of intake and exhaust gases, and so on is a valve lift. The valve lift is a scale representing the distance of a valve face from a valve seat. Generally, an increase in the valve lift leads to an increase in the amount of fuel-air gas drawn into the cylinder through the intake valve and to an increase in the amount of combustion gas expelled from the cylinder through the exhaust valve. Accordingly, intake and exhaust efficiency will increase in proportion to the valve lift. 
     A Continuously Variable Valve Lift (CVVL) system of the related art includes a control shaft having a control cam, a contact roller integrally coupled with a rocker arm and rotating in contact with a cam of a camshaft, and a swing arm contacting the rocker arm to adjust the valve lift. A cam carrier in the form of a single plate is typically used in order to facilitate assembling a cam or the like to the upper portion of a cylinder head. 
     A typical actuator shaft is about Φ8, and is subjected to a great amount of stress since it is driven by a motor. Accordingly, the cam carrier is required to adopt a structure for lubricating an actuator shaft and preventing the actuator from being deformed. 
     The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
     BRIEF SUMMARY OF THE INVENTION 
     Various aspects of the present invention provide a cam carrier assembly that can stably support the actuator shaft while defining, therein, a lubrication passage feeding lubricating oil to an actuator shaft. 
     There is provided a cam carrier assembly capable of preventing a cam carrier assembly from being deformed by twisting. 
     In an aspect of the invention, the cam carrier assembly may include at least a cam carrier mounted on a cylinder head and including a support, an actuator shaft, a portion of which is mounted in the support and rotatable to control a valve life, and a cap mounted on the cylinder head and coupled to the at least a cam carrier to rotatably support the portion of the actuator shaft and surrounding and rotatably supporting the other portion of the actuator shaft, which is not surrounded by the support. 
     The support may include a first recess having a substantially semi-circular cross section so as to rotatably receive the portion of the actuator shaft therein. 
     The at least a cam carrier may further include a seating portion and a seating surface, the seating portion and the seating surface extending from the support along a longitudinal direction of the actuator shaft to an adjacent cam carrier, and wherein the seating surface is formed on one side of the seating portion and has an arc-shaped cross section to receive the other portion of the actuator shaft therein. 
     The cap may include a fixing portion fixedly contacting the support of the at least a cam carrier to rotatably support the portion of the actuator shaft and an extension fixedly contacting the seating portion to rotatably support the other portion of the actuator shaft. 
     The extension may include a seating surface having a substantially arc-shaped cross section such that the seating surface of the seating portion and the seating surface of the extension form a substantially semi-circular cross-section, while the at least a cam carrier and the cap are assembled, to rotatably support the other portion of the actuator shaft. 
     The fixing portion of the cap may include a second recess having a substantially semicircular cross section to rotatably receive the portion of the actuator shaft therein, wherein the first and second recesses define a mounting hole into which the portion of the actuator shaft is rotatably fitted, and wherein the mounting hole communicates with a lubrication passage that allows lubricating oil to pass through. 
     The mounting hole may fluid-communicate with the seating surfaces of the seating portion and the extension, wherein the lubrication passage is formed in the at least a cam carrier. 
     The lubrication passage may communicate with a cam lubrication passage feeding the lubricating oil to a cam and a swing arm lubrication passage feeding the lubricating oil to a swing arm, and wherein the lubrication passage, the cam lubrication passage, and the swing arm lubrication passage are formed in the at least a cam carrier. 
     In another aspect of the present invention, the fixing portion may include, a first vertical surface vertically contacting a side of the support of the at least a cam carrier, a horizontal surface extending from a lower end of the first vertical surface and horizontally contacting another side of the support, and a second vertical portion extending downwards from a distal end of the horizontal surface and vertically contacting the other side of the support. 
     The second vertical surface may include the second recess and the support including the first recess may be coupled to the second recess of the second vertical surface to define a mounting hole into which the portion of the actuator shaft is rotatably fitted, and wherein the mounting hole communicates with a lubrication passage that allows lubricating oil to pass through. 
     According to various aspects of the present invention, the actuator shaft can be stably fed with lubricating oil and be stably fixed. In particular, it is possible to feed oil to a lubricating mechanism of first and second cams (i.e., a CVVA device) and to the second cam by forming an effective oil circuit of two lines. 
     In addition, the structure of the cam carrier can be reinforced to prevent the cam carrier from being deformed by twisting, in which otherwise an engine may be damaged. 
     The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description of the Invention, which together serve to explain certain principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an assembled perspective view illustrating a portion of a cam carrier assembly in accordance with an exemplary embodiment of the present invention; 
         FIG. 2  is an exploded perspective view illustrating the a portion of the cam carrier assembly shown in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view illustrating the a portion of the cam carrier assembly shown in  FIG. 1 ; and 
         FIG. 4  is a top plan view illustrating the cam carrier assembly shown in  FIG. 1 . 
     
    
    
     It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. 
     In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
     In the accompanying drawings, the parts not essential to the present invention or similar to those of the related art are omitted or simplified for the sake of clarity. 
     First, the present invention will be described with reference to  FIG. 1 , which is an assembled perspective view illustrating a portion of a cam carrier assembly in accordance with an exemplary embodiment of the present invention. 
     The cam carrier assembly of this embodiment includes a cam carrier mounted on a cylinder head, an actuator shaft  30  fixed by the cam carrier  10 , and a cap  40  supporting the actuator shaft  30 .  FIG. 1  shows only some portion of the cam carrier  10 , but the other portion is omitted since they may make the subject matter of an exemplary embodiment of the present invention rather unclear. 
     As shown in  FIG. 1 , some portions of the actuator shaft  30  are exposed whereas the other portions of the actuator shaft  30  are surrounded by the cam carrier  10  and the cap  40 . In particular, the cam carrier  10  and the cap  40  can seat and support, thereon, some portion of the underside of the actuator shaft  30 . 
     The actuator shaft  30  is rotatable so as to adjust the lift of a valve. The actuator shaft  30  has a substantially cylindrical shape. The actuator shaft  30  can be rotated by a motor in order to adjust the lift of a Continuously Variable Valve Lift (CVVL) system. 
     Below, the exemplary embodiment of the present invention will be described with reference to  FIG. 2 , which is an exploded perspective view of the portion of the cam carrier assembly shown in  FIG. 1 . 
     The cam carrier  10  is mounted on the cylinder head, and has a number of components such as a cam shaft mounted thereon. The cam carrier  10  also defines a lubrication passage therein such that the components can be lubricated by oil as explained later. 
     A support  20  surrounding a portion of the actuator shaft  30  is disposed on one side of the cam carrier  10 . The support  20  includes a recess  26 , a seating portion  22 , and a seating surface  24  thereof extending along the longitudinal direction of the actuator shaft  30 . 
     The actuator shaft  30  is seated on the seating surface  24 . Furthermore, the recess  26  may have a substantially semicircular cross section such that the actuator shaft  30  can stably rotate therein while maintaining contact with the seating surfaces  24 . This feature can be realized due to the cylindrical overall shape of the actuator shaft  30 . 
     The cap  40  is mounted on one side of the cam carrier  10 , particularly, adjacent to the support  20  to fix the actuator shaft  30 . 
     The cap  40  includes fixing portions  42  fixed to the support  20  and an extension  52  fixedly contacting the seating portion  22 . 
     Like the support  20 , the extension  52  has a seating surface capable of surrounding and supporting a portion of the actuator shaft  30 . The seating surface of the extension  52  and the seating surface  24  of the seating portion  22  are joined together to surround about half of the cross section of the shaft  30 . In particular, the seating surface of the extension  52  and the seating surface  24  of the seating portion  22  can surround the bottom of the actuator shaft  30 . With this configuration, some portion of the actuator shaft  30  can be exposed without being concealed by the seating surface of the extension  52  or the seating surface  24  of the seating portion  22 . 
     Each of the fixing portions  42  has a first vertical surface  44 , a horizontal surface  46  and a second vertical surface  48 , which are in contact with corresponding portions of the support  20 . The first vertical surface  44 , the horizontal surface  46 , and the second vertical surface  48  are connected in sequence, thereby forming an “N” like shape (more particularly, similar to a figure            
     The first vertical surface  44  has a bolt hole  50  therein, and can vertically contact the support  20 . The horizontal surface  46  horizontally extending from the lower end of the first vertical surface  44  can horizontally contact the support  20 . The second vertical surface  48  vertically extending down from the distal end of the horizontal surface  46  can vertically contact the support  20 . 
     In particular, the second vertical surface  48  has a recess that can cooperate with the corresponding portion of the support  20  to define a mounting hole  54  (see  FIG. 3 ) as will be described later. 
     Below, an exemplary embodiment of the present invention will be described with reference to  FIG. 3 , which is a cross-sectional view illustrating the a portion of the cam carrier assembly shown in  FIG. 1 . In  FIG. 3 , the cam carrier  10 , the support  20  and the cap  40  are shown in an assembled state, but the actuator shaft  30  is omitted. 
     The mounting hole  54  is formed by the joint between the second vertical surface  48  and the corresponding portion of the support  20  (see  FIG. 2 ), such that the actuator shaft  30  (see  FIGS. 1 and 2 ) can be fitted into the mounting hole  54 . The mounting hole  54  is formed by the joint between the recess of the support  20  and the recess of the second vertical surface  48 . Thus, the cavity of the mounting hole  54  is divided into two parts, with one defined by the support  20  and the other one defined by the second vertical surface  48 . 
     The cam carrier  10  defines, therein, a lubrication passage  12 , through which lubricating oil can be fed and distributed. The lubrication passage  12  can communicate with an oil pump. In particular, the mounting hole  54  can communicate with the lubricating passage  12  to feed the lubricating oil to the actuator shaft, thereby lubricating the actuator shaft. 
     In addition, since the oil can gather in the semicircular passage, defined by the joint between the seating surface  24  of the seating portion  22  and the seating surface of the extension  52 , the actuator shaft can be continuously lubricated. 
     In particular, the lubrication passage  12  in the cam carrier  10  can communicate with a cam lubrication passage  16  feeding lubricating oil to a cam and a swing arm lubrication passage  14  feeding lubricating oil to a swing arm. Thus, the actuator shaft can be lubricated using the lubrication passage  12  communicating with existing components such as the cam lubrication passage  16  and the swing arm lubrication passage  14 . 
     Since various surfaces (i.e., three surfaces) of the fixing portion  42 , such as the first vertical surface  44 , the horizontal surface  46  and the second vertical surface  48 , come into contact with the support  20 , the fixing portion  42  can be more stably fixed. A bolt  60  is fixedly fitted into the bolt hole  50  in the first vertical surface  44 . 
     When the actuator shaft is rotating, its motion may generate a force separating the cap  40  from the support  20 . However, the horizontal surface  46  joined with the support  20  in a horizontal direction generates a frictional force that can reduce the separating force, and the lower portion of the second vertical surface  48  is pressed by the cylinder head. As a result, the cap  40  can be stably mounted on the support  20 . 
     The fixing portion  42  has an “N” like overall shape (more particularly, similar to a figure             and is interposed between the cam carrier  10  and the cylinder head. Due to this interposed configuration of the fixing portion  42 , the axial force of the bolt  60  fitted into the cam carrier  10  also helps the cap  40  be stably fixed to the support  20 .
     In addition, the bolt  70  can be fixedly fitted into the upper portion of the lubrication passage  12 . 
     Now, the present invention will be described with reference to  FIG. 4 , which is a top plan view illustrating the cam carrier assembly shown in  FIG. 1 . 
     The support  20  provided on the cam carrier  10  can generally prevent the cam carrier  10  from being twisted. In particular, the seating portion  22  of the support  20  extending along the length is connected with protrusions of the cam carrier  10 . Specifically, a mounting structure of the actuator shaft  30  can be provided on an either end of the lower part of the cam carrier  10 , and the strength of the cam carrier  30  against a lateral directional force can be enhanced. 
     As shown in  FIG. 4 , when clockwise twisting is applied, the cam carrier without the seating portion  22  may be deformed. In contrast, the seating portion  22  prepared as above can enhance rigidity to reduce the likelihood of torsional deformation. 
     A description will be given of the operation of the afore-mentioned cam carrier assembly. 
     The actuator shaft  30  is subjected to a great amount of stress since it determines the amount of valve lift. Accordingly, it is required to minimize a deformation in the actuator shaft  30 . 
     According to one exemplary embodiment of the invention, only about half (½) of the actuator shaft  30  is surrounded and supported by the seating portion  22  and the extension  52 . Of course, the actuator shaft  30  can be fixed to the cam carrier assembly so as to be rotatable. This is because, in places where the support  20  is joined with the fixing portions  42  of the cap  40 , the actuator shaft  30  is entirely surrounded. 
     When an engine is running, lubricating oil is fed into the lubrication passage  12 , and then into the cam lubrication passage  16  and the swing arm lubrication passage  14 . The oil flows up to the mounting hole  54  communicating with the lubrication passage  12 . Then, the oil can gather in the seating surface  24  of the seating portion  22  and the seating surface of the extension while flowing along the actuator shaft  30  fitted into the mounting hole  54 . This, as a result, can facilitate lubrication of the actuator shaft  30 . 
     In addition, the support  20 , particularly, the seating portion  22  can enhance the rigidity of the cam carrier  10  to reduce twisting since it is provided on either side of the cam carrier  10 . 
     The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.