Patent Publication Number: US-9835057-B2

Title: Continuous variable valve duration apparatus and engine provided with the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to and the benefit of Korean Patent Application No. 10-2014-0175837 filed on Dec. 9, 2014, the entire contents of which is incorporated herein for all purposes by this reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a continuous variable valve duration apparatus and an engine provided with the same. More particularly, the present invention relates to a continuous variable valve duration apparatus an engine provided with the same which may vary opening duration of a valve according to operation conditions of an engine with a simple construction. 
     Description of Related Art 
     An internal combustion engine generates power by burning fuel in a combustion chamber in an air media drawn into the chamber. Intake valves are operated by a camshaft in order to intake the air, and the air is drawn into the combustion chamber while the intake valves are open. In addition, exhaust valves are operated by the camshaft, and a combustion gas is exhausted from the combustion chamber while the exhaust valves are open. 
     Optimal operation of the intake valves and the exhaust valves depends on a rotation speed of the engine. That is, an optimal lift or optimal opening/closing timing of the valves depends on the rotation speed of the engine. In order to achieve such optimal valve operation depending on the rotation speed of the engine, various researches, such as designing of a plurality of cams and a continuous variable valve lift (CVVL) that can change valve lift according to engine speed, have been undertaken. 
     Also, in order to achieve such an optimal valve operation depending on the rotation speed of the engine, research has been undertaken on a continuously variable valve timing (CVVT) apparatus that enables different valve timing operations depending on the engine speed. The general CVVT may change valve timing with a fixed valve opening duration. 
     However, the general CVVL and CVVT are complicated in construction and are expensive in manufacturing cost. 
     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 
     Various aspects of the present invention are directly providing a continuous variable valve duration apparatus and an engine provided with the same which may vary opening duration of a valve according to operation conditions of an engine, with a simple construction. 
     According to various aspects of the present invention, a continuous variable valve duration apparatus may include a camshaft, a plurality of wheels mounted to the camshaft, of which a wheel key is formed thereto respectively, a plurality of cam portions of which a cam and a cam key are formed thereto respectively, of which the camshaft is inserted thereto, of which relative phase angle with respect to the camshaft is variable, a plurality of inner brackets connected with the each wheel key and the each cam key, a plurality of slider housings of which the each inner bracket is rotatably inserted thereto, and movable up and down direction of an engine, a control portion selectively moving the slider housings so as to adjust relative position of a rotation center of the inner brackets and a guider guiding movement of the sliding housings. 
     The continuous variable valve duration apparatus may further include first pins of which a wheel key slot, the each wheel key is slidably inserted thereto, is formed thereto respectively and second pins of which a cam key slot, the each the cam key is slidably inserted thereto, is formed thereto respectively, and wherein a first sliding pin hole and a second sliding pin hole, of which the first pin and the second pin are inserted thereto respectively may be formed to the inner bracket. 
     The first pin and the second pin may be formed as a circular cylinder shape and the first sliding pin hole and the second sliding pin hole may be formed for the first pin and the second pin to be rotated within thereto. 
     The wheel key slot of the first pin and the cam key slot of the second pin may be formed opposite direction. 
     Parts of the first sliding pin hole and the second sliding pin hole may be opened for movements of the wheel key and the cam key not to be interrupted. 
     The continuous variable valve duration apparatus may further include a bearing inserted between the slider housing and the inner bracket. 
     A control thread may be formed to a side of the slider housings respectively, and wherein the control portion may include a control shaft parallel to the camshaft and control gears engaged with the each control thread are connected thereto and a motor selectively rotating the control shaft. 
     The guider may include a guide bar guiding movements of the slider housings and guide brackets fixing the guide bar, and wherein a guide slot may be formed to the each slider housing respectively for the guide bar is inserted thereto. 
     The wheels may be connected to the camshaft through connecting pins respectively. 
     According to various aspects of the present invention, an engine may include a camshaft, a plurality of wheels mounted to the camshaft, of which a wheel key is formed thereto respectively, and disposed corresponding to each cylinder, a plurality of cam portions of which a cam and a cam key are formed thereto respectively, of which the camshaft is inserted thereto, of which relative phase angle with respect to the camshaft is variable and disposed corresponding to the each cylinder, a plurality of inner brackets of which a first sliding pin hole and a second sliding pin hole, connected with the each wheel key and the each cam key; are formed respectively thereto, a plurality of slider housings of which the each inner bracket is rotatably inserted thereto, and movable up and down direction of the engine, first pins of which a wheel key slot, the each wheel key is slidably inserted thereto, is formed thereto respectively and rotatably inserted into the first sliding pin hole, second pins of which a cam key slot, the each the cam key is slidably inserted thereto, is formed thereto opposite to the wheel key slot respectively, and rotatably inserted into the second sliding pin hole, a control portion selectively moving the slider housings so as to adjust relative position of a rotation center of the inner brackets and a guider guiding movement of the sliding housings. 
     Parts of the first sliding pin hole and the second sliding pin hole may be opened for movements of the wheel key and the cam key not to be interrupted. 
     The engine may further include a bearing inserted between the slider housing and the inner bracket. 
     A control thread may be formed to a side of the slider housings respectively, wherein the control portion may include a control shaft parallel to the camshaft and control gears engaged with the each control thread are connected thereto and a motor selectively rotating the control shaft. 
     The guider may include a guide bar guiding movements of the slider housings and guide brackets fixing the guide bar, and wherein a guide slot may be formed to the each slider housing respectively for the guide bar is inserted thereto. 
     The wheels may be connected to the camshaft through connecting pins respectively. 
     As described above, a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention may vary an opening duration of a valve according to operation conditions of an engine, with a simple construction. 
     The continuous variable valve duration apparatus according to an exemplary embodiment of the present invention may be reduced in size and thus the entire height of a valve train may be reduced. 
     Since the continuous variable valve duration apparatus may be applied to an existing engine without excessive modification, thus productivity may be enhance and production cost may be reduced. 
     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, which together serve to explain certain principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an engine provided with a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention. 
         FIG. 2  is an exploded perspective view of a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention. 
         FIG. 3  and  FIG. 4  are partial exploded perspective views of a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention. 
         FIG. 5  is a drawing showing operation of a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention. 
         FIG. 6  and  FIG. 7  are drawings showing mechanical motions of cams of a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention. 
         FIG. 8  is a graph of a valve profile of a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention. 
     
    
    
     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 
     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 the 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 following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration. 
     As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention 
     A part irrelevant to the description will be omitted to clearly describe the present invention, and the same or similar elements will be designated by the same reference numerals throughout the specification. 
     Throughout the specification and the claims, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. 
     An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a perspective view of an engine provided with a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention,  FIG. 2  is an exploded perspective view of a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention and  FIG. 3  and  FIG. 4  are partial exploded perspective views of a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 1  to  FIG. 4 , an engine according to an exemplary embodiment of the present invention includes an engine block  1 , and a cylinder head  10  disposed on the engine block  1  and a continuous variable valve duration apparatus mounted to the cylinder head  10 . 
     The continuous variable valve duration apparatus includes a camshaft  30 , a plurality of wheels  60  mounted to the camshaft  30 , of which a wheel key  62  is formed thereto respectively, a plurality of cam portions  70  of which a cam  71  and/or  72  and a cam key  74  are formed thereto respectively, of which the camshaft  30  is inserted thereto, of which relative phase angle with respect to the camshaft  30  is variable, a plurality of inner brackets  80  connected with the each wheel key  62  and the each cam key  74 , a plurality of slider housings  90  of which the each inner bracket  80  is rotatably inserted thereto, and movable up and down direction of an engine, a control portion  100  selectively moving the slider housings  80  so as to adjust relative position of a rotation center of the inner brackets  80  and a guider  110  guiding movement of the sliding housings  80 . 
     The camshaft  30  may be an intake camshaft or an exhaust camshaft. 
     In the drawing, the cam  71  and  72  is formed as a pair, but it is not limited thereto. 
     The cams  71  and/or  72  contacts to open valve  200 . 
     The engine includes a plurality of cylinders  201 ,  202 ,  203  and  204 , and the plurality of wheels  60  and the plurality of the cam portions are disposed corresponding to the each cylinder  201 ,  202 ,  203  and  204  respectively. In the drawing, 4 cylinders are formed to the engine, but it is not limited thereto. 
     Engage holes  33  are formed to the camshaft  30  and the each wheel  60  is connected to the camshaft  30  by a connecting pin  64  through the engaging hole  33 . A connecting spring  66  is disposed to the wheel  60  for the connecting pin  64  not to be separated. 
     The continuous variable valve duration apparatus further includes first pins  82  of which a wheel key slot  81 , the each wheel key  62  is slidably inserted thereto, is formed thereto respectively and second pins  84  of which a cam key slot  83 , the each the cam key  74  is slidably inserted thereto, is formed thereto respectively. And a first sliding pin hole  86  and a second sliding pin hole  88 , of which the first pin  82  and the second pin  84  are inserted thereto respectively are formed to the inner bracket  80 . 
     The first pin  82  and the second pin  84  are formed as a circular cylinder shape and the first sliding pin hole  86  and the second sliding pin hole  88  are formed for the first pin  82  and the second pin  84  to be rotated within thereto. 
     Since the first pin  82 , the second pin  84 , the first sliding pin hole  86  and the second sliding pin hole  88  are formed as a circular cylinder, thus wear resistance may be enhanced. 
     Also, productivity may be increased due to simple shapes of the first pin  82 , the second pin  84 , the first sliding pin hole  86  and the second sliding pin hole  88 . 
     The wheel key slot  81  of the first pin  82  and the cam key slot  83  of the second pin  84  are formed opposite direction. 
     Parts of the first sliding pin hole  86  and the second sliding pin hole  88  are opened for movements of the wheel key  62  and the cam key  74  not to be interrupted. 
     A bearing  92  is inserted between the slider housing  90  and the inner bracket  80 . Thus, rotation of the inner bracket  80  may be easily performed. 
     In the drawings, the bearing  92  is depicted as a needle bearing, however it is not limited thereto. On the contrary, various bearings such as a ball bearing, a roller bearing and so on may be applied thereto. 
     A control thread  94  is formed to a side of the slider housings  90  respectively. And the control portion  100  includes a control shaft  102  parallel to the camshaft  30  and control gears  104  engaged with the each control thread  94  are connected to the control shaft  102  thereto and a motor  108  selectively rotating the control shaft  102 . 
     The guider  110  includes a guide bar  112  guiding movements of the slider housings  90  and guide brackets  114  fixing the guide bar  112 . And a guide slot  95  is formed to the each slider housing  90  respectively for the guide bar  112  is inserted thereto. 
       FIG. 5  is a drawing showing operation of a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention and  FIG. 6  is a graph of a valve profile of a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 1  to  FIG. 6 , operations of the continuous variable valve duration apparatus according to various aspects of the present invention will be discussed. 
     As shown (b) of  FIG. 5 , since a rotation center of the inner bracket  80  coincides with a rotation center of the cam shaft  30 , relative rotation speed changes between the cam  71  and  72  are not occurred. That is, the cam  71  and  72  and the cam shaft  30  rotates with same speed and same phase. 
     According to engine operation states, an ECU (engine control unit or electric control unit) transmutes control signals to the motor  108  of the control portion  100  to change a relative position of the slider housing  90 . 
     For example, from the state of (a) of  FIG. 5 , when the motor  108  rotates the control shaft  102  for the slider housing  90  to be moved upward as shown (b) of  FIG. 5 , the rotation center of the inner bracket  80  moves up as ΔH 1 , or when the motor  108  rotates the control shaft  102  for the slider housing  90  to be moved downward as shown (c) of  FIG. 5 , the rotation center of the inner bracket  80  moves down as ΔH 2 . 
     When the rotation center of the inner bracket  80  is changed, angular acceleration of the cam portion  70  and valve duration are changed. 
       FIG. 6  and  FIG. 7  are drawings showing mechanical motions of cams of a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 5  and  FIG. 6 , while the phase angle of the camshaft  30  is constantly changed when the relative rotation center of the cams  71  and  72  with respect to the rotation center of the camshaft  30  is changed downward, the rotation speed of the cams  71  and  72  is relatively faster than rotation speed of the camshaft  30  from phase a to phase b and from phase b to phase c, then the rotation speed of the cams  71  and  82  is relatively slower than rotation speed of the camshaft  30  from phase c to phase d and from phase d to phase a. That is, the valve duration is changed. 
     As shown in  FIG. 5  and  FIG. 7 , while the phase angle of the camshaft  30  is constantly changed when the relative rotation center of the cams  71  and  72  with respect to the rotation center of the camshaft  30  is changed upward, the rotation speed of the cams  71  and  72  is relatively slower than rotation speed of the camshaft  30  from phase a to phase b and from phase b to phase c, then the rotation speed of the cams  71  and  82  is relatively faster than rotation speed of the camshaft  30  from phase c to phase d and from phase d to phase a. That is, the valve duration is changed. 
     While the wheel  60  is rotated together with the camshaft  30 , the wheel key  62  is slidable within the wheel key slot  81 , the first pin  82  and the second pin  84  are rotatable within the first sliding pin hole  86  and the second sliding pin hole  88  respectively and the cam key  74  is slidable within the cam key slot  83 . Thus, when the relative rotation centers of the inner bracket  80  and the camshaft  30  are changed, the relative rotation speed of the cams  71  and  72  with respect to the rotation speed of the camshaft  30  is changed. 
     That is, as shown in  FIG. 8 , although maximum lift of the valve  200  is constant, however rotation speed of the cam  71  and  72  with respect to the rotation speed of the camshaft  30  is changed according to relative positions of the slider housing  90  so that closing and opening time of the valve  200  is changed. That is, duration of the valve  200  is changed. 
     While opening time of the valve  200  is constant, closing time of the valve  200  is changed in  FIG. 8 , it is not limited thereto. According to various mounting angle of the cams  71  and  72  and the valve  200 , various contacting angles between cam lobe of the cams  71  and  72  and the valve  200  and so on, various valve duration may be performed. 
     Determinations of the control signals of the ECU according to the engine operation state is obvious to a person skilled in the art, thus detailed description will be omitted. 
     As described above, a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention may vary an opening duration of a valve according to operation conditions of an engine, with a simple construction. 
     The continuous variable valve duration apparatus according to an exemplary embodiment of the present invention may be reduced in size and thus the entire height of a valve train may be reduced. 
     Since the continuous variable valve duration apparatus may be applied to an existing engine without excessive modification, thus productivity may be enhance and production cost may be reduced. 
     For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner” and “outer” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
     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.