Abstract:
An engine that may be provided with a variable valve device may include an hydraulic pressure lash adjuster pivotally supporting one side of a swing arm, a valve supporting the other side of the swing arm, and an operating portion pushing a portion of the swing arm downwards so as to pivotally move the valve based on the hydraulic pressure lash adjuster, wherein the hydraulic pressure lash adjuster includes a housing in which an insertion hole may be formed therein, a slave piston that may be slidably inserted into the insertion hole, a master piston of which an end thereof may be placed into the insertion hole with a predetermined gap from the slave piston, wherein the other end of the master piston protrudes out of the housing and may be engaged with the one side of the swing arm, and an oil control valve that opens or closes a passage communicating with a master chamber that may be formed between the master piston and the slave piston in the housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority to Korean Patent Application No. 10-2010-0092696 filed in the Korean Intellectual Property Office on Sep. 20, 2010, the entire contents of which is incorporated herein for all purposes by this reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an engine provided with a variable valve device that variably controls a motion of a valve disposed at an intake port or an exhaust port of a combustion chamber so as to improve fuel efficiency. 
         [0004]    2. Description of Related Art 
         [0005]    Some means for varying the timing of valve actuation of internal combustion engines are very well known. Such means typically take the form of a camshaft, a rocker arm, or a finger follower so as to control the valve motion. 
         [0006]    A variable valve device is especially well known in spark ignited engines, in which it is an essential element of various schemes for improving fuel economy, and there is a method using a profile of a cam to control valve lift and using a lost motion so as to control valve lift. 
         [0007]    Meanwhile, a pivot portion is used so as to reduce a gap between a valve and a swing arm in a variable valve train, but it is difficult to simply or compactly constitute the variable valve train and the hydraulic pressure lash adjuster in a restricted space. 
         [0008]    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 
       [0009]    Various aspects of the present invention are directed to provide an engine that is provided with a variable valve device having advantages of constituting a hydraulic pressure lash adjuster and a valve deactivation device in a simple structure. 
         [0010]    In an aspect of the present invention, the engine that may be provided with a variable valve device, may include an hydraulic pressure lash adjuster pivotally supporting one side of a swing arm, a valve supporting the other side of the swing arm, and an operating portion pushing a portion of the swing arm downwards so as to pivotally move the valve based on the hydraulic pressure lash adjuster, wherein the hydraulic pressure lash adjuster may include a housing in which an insertion hole may be formed therein, a slave piston that may be slidably inserted into the insertion hole, a master piston of which an end thereof may be placed into the insertion hole with a predetermined gap from the slave piston, wherein the other end of the master piston protrudes out of the housing and may be engaged with the one side of the swing arm, and an oil control valve that opens or closes a passage communicating with a master chamber that may be formed between the master piston and the slave piston in the housing. 
         [0011]    The engine may further include a stopper that may be disposed inside the insertion hole such that the slave piston cannot move towards the master piston, a master spring that elastically supports the master piston outwards in the master chamber, and a slave spring that elastically supports the slave piston towards the stopper in the insertion hole. 
         [0012]    A slave chamber may be formed between an end surface of the slave piston and an inside end surface of the insertion hole of the housing, and a drain hole through which oil in the slave chamber may be exhausted may be formed thereto. 
         [0013]    A brake chamber may be formed by a slave step of which an exterior diameter of the slave piston becomes narrower, an housing inside surface of the housing, a housing step of which an interior diameter of the housing becomes narrower, and a slave outside surface of the slave piston at an opposite side of the master piston, wherein the slave outside surface of the slave piston and the inside end surface of the insertion hole may be slidably in contact and the housing inside surface and external circumference of the slave piston may be slidably in contact. 
         [0014]    A brake chamber may be formed by a slave step of which an exterior diameter of the slave piston becomes narrower, a housing inside surface, a housing step of which an interior diameter of the housing becomes narrower, and a slave outside surface of the slave piston at an opposite side of the master piston, wherein an orifice may be formed in the slave piston so as to connect the brake chamber with the slave chamber, wherein the slave outside surface of the slave piston and the inside end surface of the insertion hole may be slidably in contact and the housing inside surface and external circumference of the slave piston may be slidably in contact. 
         [0015]    The engine may further a brake chamber oil supply line that may be connected to the brake chamber for supplying the brake chamber with oil. 
         [0016]    The engine may further include a latching pin slidably disposed in a latching chamber formed in the master piston to selectively fix the master piston to the housing such that the master piston cannot move in the housing, and a hydraulic pressure supply portion that supplies one side of the latching pin with hydraulic pressure in the latching chamber so as to move the latching pin, wherein an end of the latching pin may be slidably inserted into a side of the master piston and the other end thereof may be selectively inserted into a side of the housing such that the master piston may be selectively fixed in the housing. 
         [0017]    The engine may further include a return spring that elastically pushes the latching pin such that the latching pin may be biased to the housing, wherein latching pins may be respectively disposed at both sides based on a center portion of the master piston in the latching chamber, each end portion thereof may be selectively inserted through the master piston into the housing, and the hydraulic pressure supply portion supplies the latching pins with hydraulic pressure through the housing and the master piston. 
         [0018]    A latching chamber may be formed at an interior circumference of the housing and the latching pin may be slidably inserted into the latching chamber, a latching groove may be formed at an exterior circumference of the master piston corresponding to the latching chamber to selectively receive the latching pin therein, and the hydraulic pressure supply portion selectively supplies hydraulic pressure to the latching chamber to latch the latching pin with the latching groove such that the housing and the master piston may be fixed or slides from each other, wherein a latching spring may be disposed in the latching chamber to elastically supports the latching pin. 
         [0019]    As stated above, a variable valve device is provided in a hydraulic pressure lash adjuster such that the overall structure becomes small and the weight can reduced in an engine that is provided with a variable valve device according to the present invention. 
         [0020]    Further, motion of the swing arm can be accurately controlled by the slave piston so as to variably control the valve actuation. 
         [0021]    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 
         [0022]      FIG. 1  is a cross-sectional side view of an engine that is provided with a variable valve device according to an exemplary embodiment of the present invention. 
           [0023]      FIG. 2  is a cross-sectional side view showing a swing arm performing a lost motion in an engine that is provided with a variable valve device according to an exemplary embodiment of the present invention. 
           [0024]      FIG. 3  is a cross-sectional side view showing a swing arm moving a valve in an engine that is provided with a variable valve device according to an exemplary embodiment of the present invention. 
           [0025]      FIG. 4  is a cross-sectional side view of an engine that is provided with a variable valve device according to other exemplary embodiment of the present invention. 
           [0026]      FIG. 5  is a cross-sectional side view of an engine that is provided with a variable valve device according to another exemplary embodiment of the present invention. 
       
    
    
       [0027]    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. 
         [0028]    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 
       [0029]    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. 
         [0030]    An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings. 
         [0031]      FIG. 1  is a cross-sectional side view of an engine that is provided with a variable valve device according to an exemplary embodiment of the present invention. 
         [0032]    Referring to  FIG. 1 , a camshaft  100  is disposed at the top thereof, a swing arm  120  is disposed at the lower side of the camshaft  100 , a valve  130  is disposed at the lower left side of the swing arm  120 , and a hydraulic pressure lash adjuster is disposed at a right side of the swing arm  120 . The hydraulic pressure lash adjuster includes a housing  185  that covers the outside, and a master piston  140  that protrudes at the upper side of the housing  140 . 
         [0033]    The valve  130  supports the left lower portion of the swing arm  120 , and the hydraulic pressure lash adjuster supports the right lower portion of the swing arm  120 . 
         [0034]    A roller  110  is disposed at the middle upper side of the swing arm  120 , and the roller  100  contacts a cam lobe of the camshaft  100 . The valve  130  is elastically supported by a valve spring that is not shown in  FIG. 1 . 
         [0035]    If the camshaft  100 , as an operating portion, rotates, the cam lobe of the camshaft  100  pushes the roller  110  downwards such that the valve  130  is moved downwards. 
         [0036]    Hereinafter, a structure of the hydraulic pressure lash adjuster will be described with reference to the figures. 
         [0037]    The hydraulic pressure lash adjuster includes the housing  185 , the master piston  140 , a master spring  155 , a stopper  197 , a slave piston  180 , a slave spring  170 , and a oil control valve  150 . 
         [0038]    An insertion hole  105  is formed in the housing, the insertion hole is opened to the upper side, and the slave spring  170 , the slave piston  180 , the stopper  197 , the master spring  155 , and the master piston  140  are sequentially inserted into the insertion hole. 
         [0039]    The slave spring  170  elastically supports the slave piston  180  upwards, and the stopper  197  restricts the motion of the slave piston such that the slave piston  180  is not drawn out. Accordingly, the edge upper surface of the slave spring  170  contacts the lower surface of the stopper  197 . 
         [0040]    A lower end of the master spring  155  is supported by the stopper  197 , and an upper end thereof elastically supports the master spring  155  upwards. Accordingly, the upper end of the master piston  140  contacts the lower surface of the swing arm  120 . 
         [0041]    The exterior circumference of the master piston  140  contacts the interior of the housing  185  around the circumference thereof, and a master chamber  145  that is formed between the master piston  140  and the slave piston  180  is a sealed space. 
         [0042]    Further, the exterior circumference of the slave piston  180  contacts the interior of the housing  185  around the circumference thereof, and the slave chamber  174  is formed between the slave piston  180  and the inside end surface of the housing  185 . 
         [0043]    The oil control valve  150  selectively opens a passage communicating with the master chamber  145  to induce a lost motion of the master piston  140 . 
         [0044]      FIG. 2  is a cross-sectional side view showing a swing arm performing a lost motion in an engine that is provided with a variable valve device according to an exemplary embodiment of the present invention. 
         [0045]    Referring to  FIG. 2 , while the oil control valve  150  is opened, if the camshaft  100  rotates, the roller  110  of the swing arm  120  moves downwards, and the swing arm  120  pushes the valve  130  and the master piston  140  downwards. 
         [0046]    In this case, the master piston  140  is inserted into the inside of the housing  185 , and the valve  130  is supported by a valve spring to not move. Further, the master spring  155 , which is disposed between the master piston  140  and the stopper  197 , is compressed. 
         [0047]    Further, because the oil control valve  150  is opened, the hydraulic pressure formed in the master chamber  145  is exhausted through the oil control valve  150 , and the slave piston  180  does not move. 
         [0048]      FIG. 3  is a cross-sectional side view showing a swing arm moving a valve in an engine that is provided with a variable valve device according to an exemplary embodiment of the present invention. 
         [0049]    Referring to  FIG. 3 , while the oil control valve  150  is closed, if the camshaft  100  rotates, the right side of the swing arm  120  is fixedly supported by the master piston  140 , and the valve  130  together with the left side of the swing arm  120  is forced downwards. 
         [0050]    In an exemplary embodiment of the present invention, while the oil control valve  150  is closed, if the camshaft  100  pushes the swing arm  120  and the roller  110  downwards, a force thereof is simultaneously applied to the master piston  140  and the valve  130 . 
         [0051]    Instantly, the inside pressure of the master chamber  145  is raised by the force applied to the master piston  140 , and the slave piston  180  moves downwards a small amount. Further, the master piston  140  moves downwards a small amount in accordance with the movement of the slave piston  180 . 
         [0052]    Accordingly, the early movement of the valve  130  is damped to be slowly moved. 
         [0053]    An assembly structure of the slave piston  180  and the housing  185  will be described with reference to the  FIG. 1 . 
         [0054]    At the side of the expanded part of  FIG. 1 , a slave step  164  is formed at a lower portion of the slave piston  180  such that the diameter thereof is reduced, and a housing step  162  is formed inside the housing  185  corresponding to the slave step  164  with a predetermined distance from the slave step  164 . 
         [0055]    Further, a slave outside surface  166  is formed at an exterior circumference of the slave piston  180  with a predetermined distance from a housing inside surface  168  of the housing  185 . 
         [0056]    The slave step  164 , the slave outside surface  166 , the housing step  162 , and the housing inside surface  168  form a brake chamber  195 . The brake chamber  195  is connected to a brake chamber oil supply passage  160  to receive hydraulic pressure from an oil line. Further, the brake chamber  195  is formed along the circumference of the lower end of the slave piston  180 . 
         [0057]    In addition, a slave chamber  174  is formed between the lower end of the slave piston  180  and the inside end surface  172  of the housing  185 , and the slave chamber  174  communicates with a drain hole  175 . 
         [0058]    As shown, an orifice  165  connects the brake chamber  195  with the slave chamber  174 . In this case, it is desirable that the diameters of the orifice  165  and the brake chamber oil supply passage range  160  from 0.1 to 5 mm. 
         [0059]    Referring to  FIG. 3 , if the oil control valve  150  is closed and the pressure of the master chamber  145  is increased, a downward force is applied to the slave piston  180 , and the pressure of the brake chamber  195  is increased. 
         [0060]    Further, the oil in the brake chamber  195  moves to the slave chamber  174  through the orifice  165 , and the oil of the slave chamber  174  is drained through the drain hole  175 . 
         [0061]    Further, the downward movement of the slave piston  180  is restricted by the housing step  162 . Accordingly, the valve  130  is slowly depressed during the downward movement of the slave piston  180 , and the valve is quickly depressed after the slave piston  180  is fixed downwards. 
         [0062]    Further, while the camshaft  100  rotates, if the cam does not push the swing arm  120  downwards, the slave piston  180  is returned upwards by the slave spring  170  to be supported by the stopper  197 . 
         [0063]      FIG. 4  is a cross-sectional side view of an engine that is provided with a variable valve device according to other exemplary embodiment of the present invention. 
         [0064]    As compared with the features of  FIGS. 1 ,  2 , and  3 , distinct parts will be described referring to  FIG. 4 , and a detailed description regarding similar parts will be omitted. 
         [0065]    Referring to  FIG. 4 , a latching chamber  405  is formed in the master piston  140 , which is opened to both sides, and a latching pin  410  is inserted into the latching chamber  405  to be disposed at both sides thereof. 
         [0066]    A latching spring  420  is interposed between the latching pins  410 , and the latching spring  420  elastically pulls the latching pin  410  in the central direction. 
         [0067]    The latching chamber  405  is connected to an outside oil supply line through the master piston  140  and the housing  185 , and a latching oil control valve  400  is disposed in the oil supply line. 
         [0068]    If the latching oil control valve  400  is opened, hydraulic pressure is supplied to the inside of the latching chamber  405 , and the latching pins  410  respectively move to both sides. Accordingly, the latching pin  410  is engaged with a latching groove  430  that is formed on the interior circumference of the housing  185 . 
         [0069]    If the end portion of the latching pin  410  is engaged with the latching groove  430 , the master piston  140  is fixed to the housing  185 . Accordingly, the valve  130  is depressed a large amount. 
         [0070]    If oil is not supplied to the master chamber  145  due to low supply pressure or high viscosity at a lower temperature, the oil pressure can be insufficient in the master chamber  145 . 
         [0071]    In this case, it is desirable that a hydraulic pressure is supplied to the latching chamber  405  such that the master piston  140  is fixed to the housing  185  by the latching pin  410 . 
         [0072]      FIG. 5  is a cross-sectional side view of an engine that is provided with a variable valve device according to another exemplary embodiment of the present invention. As compared with the features of  FIGS. 1 ,  2 ,  3 , and  4 , distinct parts will be described referring to  FIG. 5 , and a detailed description regarding similar parts will be omitted. 
         [0073]    Referring to  FIG. 5 , a latching groove is formed at an exterior circumference of the master piston  140  facing an interior circumference of the housing, a latching chamber  505  is formed at an interior circumference of the housing  185  corresponding to the latching groove  530 , and a latching pin  510  is inserted into the latching chamber  505 . 
         [0074]    Further, a latching spring  520  is disposed inside the latching chamber  505  and the latching spring  520  has a structure pushing the latching pin  510  outwardly. The latching chamber  505  is connected to a oil supply passage that is opened/closed by a latching oil control valve  500  to receive the hydraulic pressure depending on the ON/OFF of the latching oil control valve  500 . 
         [0075]    If the latching chamber  505  does not receive the hydraulic pressure through the latching oil control valve  500 , a front end of the latching pin  510  is inserted into the latching groove  530  by the latching spring  520  such that the master piston  140  and the housing  185  are fixed from each other. Accordingly, the valve  130  is normally lifted thereby. 
         [0076]    However, if the latching chamber  505  receives the hydraulic pressure through the latching oil control valve  500 , the latching pin  510  leaves the latching groove  530  by the latching spring  520  such that the master piston  140  slides with the housing  185 . Accordingly, the valve  130  does not move or low lifted through a lost motion. 
         [0077]    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. 
         [0078]    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.