Abstract:
A variable intake system includes an intake manifold having at least one runner, an opening/closing unit for adjusting a length of the runner, an actuator for activating the opening/closing unit, and a vacuum unit defining a vacuum chamber for driving the actuator. The vacuum unit is disposed inside the intake manifold.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2006-0069021 filed in the Korean Intellectual Property Office on Jul. 24, 2006, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    (a) Field of the Invention 
         [0003]    The present invention relates to a variable intake system for a vehicle, and more particularly, to a variable intake system with a vacuum chamber inside an intake manifold. 
         [0004]    (b) Description of the Related Art 
         [0005]    A variable intake system adjusts the runner length of an intake manifold. The variable intake system includes a throttle body, a surge tank communicating with the throttle body, an intake manifold having a plurality of runners to which air is dispensed from the surge tank, an opening/closing unit for adjusting the runner length, an actuator that activates the opening/closing unit, and a vacuum chamber for driving the actuator. 
         [0006]    Vacuum chambers have been developed as an independent engine component. The vacuum chamber can be designed without shape or size limitations to have sufficient volume. Furthermore, the mounting position of the vacuum chamber can be freely selected. 
         [0007]    The mounting position of the vacuum chamber is determined by the layout of the engine and vehicle. The vacuum chamber must be sufficient in size and the connection tube that connects the vacuum chamber must be simple in design. 
         [0008]    Further, an effort to manufacture the variable intake system using plastic has continued to reduce the weight of the engine. However, the vacuum chamber requires many components such as a mounting bracket, a bracket coupling member, an actuator, and a vacuum hose connecting the actuator to the vacuum chamber. Therefore, the manufacturing cost increases and the space taken by the vacuum chamber increases. 
         [0009]    Also, experiments show that noise increases when the variable intake system is formed of plastic. Particularly, this noise is primarily generated by the increase of a flow ratio when air passes through the throttle body, and is secondarily generated when the air passes through the runners of the intake manifold. 
         [0010]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention provides a variable intake system with relatively few components and a simple structure that takes up relatively less space. The present invention also minimizes weight, provides a vacuum chamber having a relatively large volume, and reduces noise. 
         [0012]    An exemplary embodiment of the resent invention provides a variable intake system including an intake manifold having at least one runner, an opening/closing unit for adjusting a length of the runner, an actuator for activating the opening/closing unit, and a vacuum unit defining a vacuum chamber for driving the actuator, wherein the vacuum unit is disposed inside the intake manifold. 
         [0013]    The vacuum unit may include an upper body and a lower body. The upper and lower bodies may be coupled to each other by vibration welding. An upper portion of the vacuum unit may include a curved surface inclined toward an inlet of the intake manifold. The opening/closing unit may be provided on an upper portion of the runner. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a perspective view of a variable intake system for a vehicle according to an exemplary embodiment of the present invention. 
           [0015]      FIG. 2  is a partial perspective view of a lower body of a variable intake system according to an exemplary embodiment of the present invention. 
           [0016]      FIG. 3  is a view illustrating an example where a vacuum chamber lower body is coupled to the lower body of the variable intake system of  FIG. 2 . 
           [0017]      FIG. 4  is a view illustrating an example where a vacuum chamber upper body is coupled to the vacuum chamber lower body of  FIG. 3 . 
           [0018]      FIG. 5  is a sectional view taken along line A-A of  FIG. 1 . 
           [0019]      FIG. 6  is a sectional view taken along line B-B of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings. 
         [0021]    A throttle valve  110  through which external air is introduced and an actuator  120  for operating an opening/closing unit  530  using a negative pressure from the vacuum chamber  550  are connected to a variable intake system  100  for a vehicle. 
         [0022]    A lower body  200  is placed at a lower portion of the variable intake system  100 . 
         [0023]    Referring to  FIG. 2 , a runner  210  of an intake manifold is formed in the variable intake system  100 . 
         [0024]    As shown in  FIG. 5 , the upper portion of the vacuum chamber  550  is inclined toward a runner inlet  410  and provided with a curved surface. Therefore, when the air is directed toward the runner inlet  410 , the airflow resistance is minimized. 
         [0025]    For convenience, only one of the runners of the intake manifold will be described with reference to the accompanying drawing. 
         [0026]    Referring to  FIG. 5 , the vacuum chamber upper body  400  is provided with a curved surface, being inclined toward the runner inlet  410 . 
         [0027]    As shown in  FIG. 5 , the opening/closing unit  530  for controlling the airflow is provided on an upper portion of the runner  210 . 
         [0028]    In  FIG. 5 , the throttle valve  110  is illustrated using a dotted line. 
         [0029]    The air directed into the surge tank  510  through the throttle valve  110  is further directed into the runner  210 . 
         [0030]    The opening/closing unit  530  opens and closes according to the operation of the engine. When the opening/closing unit  530  is closed, the length of the runner  210  through which the air passes increases. When the opening/closing unit  530  is opened, the length of the runner  210  through-which the air passes is reduced. 
         [0031]    When the vehicle runs at high speed, the opening/closing unit  530  is opened. When the vehicle runs at low speed, the opening/closing unit  530  is closed. 
         [0032]      FIG. 5  shows an example when the opening/closing unit  530  is open. The one-point chain line shows when unit  530  is closed. 
         [0033]    When the opening/closing unit  530  is open, air flows from the surge tank  510  into the runner  210  following the dotted arrow. 
         [0034]    The opening/closing unit  530  is controlled by the actuator  120 , which is driven by the negative pressure in the vacuum chamber  550 , generated by the surge tank  510 . 
         [0035]    The actuator  120  is controlled by an electronic control unit (ECU) (not shown). 
         [0036]    As shown in  FIG. 5 , the upper portion of the vacuum chamber  550  functions as a bell mouse that can minimize the airflow resistance when the air flows into the runner  210 . 
         [0037]    By the bell mouse having a relatively large radius, the chance of vortex generation is low. Also, the airflow resistance is low. 
         [0038]    In  FIG. 5 , air from the surge tank  510  flows into the runner  210  through the runner inlet  410  in the direction of the solid arrow. The arrow in  FIG. 5  is curved gently. This means that the airflow resistance is further reduced. 
         [0039]    Since the variable intake system of the present invention has the vacuum chamber  550  placed inside, the structural rigidity is enhanced. The intake manifold or the barrier rib can be thin and thus weight of the overall system can be reduced. 
         [0040]    Further, the volume of the vacuum chamber  550  can be enlarged without increasing the weight. 
         [0041]    The noise is reduced by an air gap effect. 
         [0042]    That is, since the vacuum chamber  550  has a different air density inside of the variable intake system, noise is reduced. Experiments show that noise is reduced throughout the entire region of the variable intake system. 
         [0043]    While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.