Abstract:
A digital linear actuator (DLA) large port throttle control valve manifold assembly which is suitable for use with various automotive engines. The sidegate capnut is sized such that the full amount of throttle body intake manifold air is controlled to the engine. Apertures are formed as part of the side gate capnut to minimize axial air loading on the capnut, providing a pressure balance. Providing a pressure balance also reduces the axial force required to position the capnut, which in turn reduces size of the actuator needed to position the capnut, thus reducing the overall size of the DLA. The positional control of the DLA along with the internal plenum port(s) window profile provides the desired air flow for each commanded position.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/155,679 filed May 1, 2015. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates generally to a valve assembly, which includes a digital linear actuator (DLA), where the valve assembly functions as an air control valve. 
       BACKGROUND OF THE INVENTION 
       [0003]    Typically, gasoline engines having electronic fuel injection (EFI) with a mechanical throttle body (MTB) include a cable driven accelerator, and a digital linear actuator (DLA) type of idle air control valve (IACV). The IACV is designed to meet vehicle emission regulations and account for cable slop and mechanical throttle body air flow and air leak. For larger and more expensive automotive engines, the MTB is being replaced by fully electronic throttle control (ETC). Furthermore, ETC and drive by wire have been steadily replacing MTB applications with EFI. The bore size of the diameter for ETC ranges between 40 millimeters (for a 1.0 L, in-line, three-cylinder engine) to 87 millimeters (for a 6.2 L, 8-cylinder engine). The current designs having ETC are limiting in size due to the size and packing of the gear train, motor, and position sensing elements. 
         [0004]    A DLA type of actuator used as an IACV utilizes an annular capnut profile type of valve that changes axial position to control idle air flow. These capnut designs are typically bath tub stopper types of valves, although in some designs, the IACV uses the capnut as a perimeter side gate valve. In any of the above-mentioned designs, the IACV is only used for limited “idle” air to control the engine, and not for controlling the required full intake air volume of an “open” throttle. 
         [0005]    Accordingly, there exists a need for a DLA which is size-suitable for smaller automotive engines and provides full electronic throttle control. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention is a DLA large port throttle control assembly which is suitable for use with smaller automotive engines. If the sidegate capnut is of sufficient diameter, the full amount of throttle body intake manifold air may be controlled to the engine. One of the features of the invention is to include apertures formed as part of the sidegate capnut to minimize axial differential air loading on the capnut, providing a pressure balance. Providing a pressure balance also reduces the axial force required to position the capnut, which in turn reduces size of the actuator needed to position the capnut, thus reducing the overall size of the DLA. The positional control of the DLA along with the internal plenum port(s) side gate window profile provides the desired throttle air flow for each commanded position. 
         [0007]    To reduce the “Reynolds” restrictive flow losses, the throttle body manifold assembly of the present invention includes at least the following two characteristics: 1) the internal plenum ports combined cross-sectional shadow area is greater than or equal to the inlet port cross-sectional shadow area, as well as the outlet port cross-sectional shadow area; and 2) the exterior plenum cavity of the housing surrounding the internal plenum side gate ports is sized sufficiently that the curtain area at the outlet port (the outlet port perimeter×radial clearance between the circumferential wall of the exterior plenum cavity and the outlet port) is larger than the outlet port cross-sectional area. If these two parameters are observed, then the pressure drop through the throttle control assembly of the present invention is minimized or eliminated. The DLA large port throttle control assembly of the present invention is suitable for electronic control with existing stepper motor engine control unit operation parameters. Placement of the internal ports around the circumference of the interior plenum cavity is such to achieve a balanced radial air load on the capnut (i.e., net radial side load force is substantially equal to zero). 
         [0008]    In one embodiment, the present invention is a throttle control valve assembly, which includes a housing, an inlet port integrally formed as part of the housing, an outlet port integrally formed as part of the housing, and an interior plenum cavity formed as part of the housing. The inlet port is selectively in fluid communication with the interior plenum cavity through the use of a valve member, which is disposed in the interior plenum cavity. An actuator is connected to the housing, and the valve member is controlled by the actuator. An exterior plenum cavity is formed as part of the housing. The exterior plenum cavity is in fluid communication with the outlet port, and is selectively in fluid communication with the interior plenum cavity. A circumferential wall is formed as part of the housing such that the circumferential wall separates the interior plenum cavity from the exterior plenum cavity, and the valve member is in contact with the circumferential wall. A plurality of internal ports are integrally formed as part of the circumferential wall such the internal ports provide selective fluid communication between the outlet port and the interior plenum cavity, and between the interior plenum cavity and the exterior plenum cavity. The actuator moves the valve member to selectively obstruct the plurality of internal ports to control the flow of air from the inlet port to the outlet port. 
         [0009]    The actuator is able to move the valve member to an open position, such that air is able to flow from the inlet port into the interior plenum cavity, where a portion of the air flows through the internal ports and directly to the outlet port, or a portion of the air flows through the exterior plenum cavity and to the outlet port. The actuator also moves the valve member to a closed position, such that the plurality of internal ports are obstructed by the valve member, and air is prevented from flowing from the interior plenum cavity through the exterior plenum cavity, to the outlet port. 
         [0010]    In one embodiment, the combined area of the plurality of internal ports is greater than the area of the outlet port, and the combined area of the plurality of internal ports is greater than the area of the inlet port. 
         [0011]    The valve member includes a capnut having a first side and a second side, at least one aperture is formed as part of the capnut, and an exterior cylindrical portion is formed as part of the capnut. The exterior cylindrical portion is in sliding contact with the circumferential wall. Air may flow through the aperture formed as part of the capnut to provide a pressure balance on the first side and the second side of the caput. The capnut is moved such that the exterior cylindrical portion selectively obstructs the plurality of internal ports as the caput is moved axially between the open position and the closed position. 
         [0012]    In an embodiment, the valve member is a side gate capnut, but it is within the scope of the invention that other types of valve members may be used. Also, the internal ports around the circumference of the interior plenum cavity are positioned as such to achieve a balanced radial air load on the capnut (i.e., the net force radial side load is substantially equal to zero). 
         [0013]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0015]      FIG. 1  is a perspective view of a throttle control valve, according to embodiments of the present invention; 
           [0016]      FIG. 2  is a side view of a throttle control valve, according to embodiments of the present invention; 
           [0017]      FIG. 3  is a sectional side view of a throttle control valve taken along lines  3 - 3  of  FIG. 4 ; 
           [0018]      FIG. 4  is a bottom view of a throttle control valve, according to embodiments of the present invention; 
           [0019]      FIG. 5  is a side view of a throttle control valve, according to embodiments of the present invention; 
           [0020]      FIG. 6  is a top view of a throttle control valve, according to embodiments of the present invention; and 
           [0021]      FIG. 7  is a sectional side view of a throttle control valve taken along lines  7 - 7  of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0023]    A throttle control valve assembly according to the present invention is shown in the Figures generally at  10 . The valve  10  includes a housing  12 , and formed as part of the housing  12  is an inlet port  14  and an outlet port  16 . Both ports  14 , 16  are in fluid communication with an interior plenum cavity, shown generally at  18 , and the interior plenum cavity  18  is separated from an exterior plenum cavity, shown generally at  20 , by a circumferential wall  22 . Part of the exterior plenum cavity  20  is also in fluid communication with the outlet port  16 , where the portion of the exterior plenum cavity  20  in fluid communication with the outlet port  16  is determined by the diameter of the outlet port  16 . Formed as part of the circumferential wall  22  is a plurality of internal ports  24 , where the outlet port  16  is in fluid communication with the interior plenum cavity  18  through one or more of the internal ports  24 , shown in  FIG. 2 . 
         [0024]    In this embodiment, the internal ports  24  are substantially square-shaped, and are 9.0 millimeters on a side, but it is within the scope of the invention that other shapes and dimensions may be used for desired flow control. The area of each of the internal ports  24  may vary, but regardless of how the internal ports  24  are shaped, the combined area of the internal ports  24  is greater than the area of inlet port  14 , and the combined area of the internal ports  24  is also greater than the area of the outlet port  16 , so as to reduce or minimize “Reynolds” restrictive flow losses of the air flowing through the valve  10 . Also, the exterior plenum cavity  18  of the housing  12  surrounding the internal ports  24  is sized sufficiently that the curtain area at the outlet port  16  (the outlet port perimeter x radial clearance between the circumferential wall  22  of the exterior plenum cavity  20  and the outlet port  16 ) is larger than the cross-sectional area of the outlet port  16 . 
         [0025]    Connected to the housing  12  is an actuator, shown generally at  26 , which in this embodiment is a stepper motor type of actuator, but it is within the scope of the invention that other types of actuators may be used. The actuator  26  includes a plunger  28 , and connected to the plunger  28  is a valve member, which in this embodiment is a side gate capnut  30 . The capnut  30  is in sliding contact with the interior plenum surface of the circumferential wall  22 . The capnut  30  includes a central valve plate  30   d,  and formed as part of the central valve plate  30   d  is a plurality of apertures  32 . The apertures  32  provide a way to ensure a pressure balance axially between a first side  30   a  of the central valve plate  30   d,  and a second side  30   b  of the central valve plate  30   d,  as the capnut  30  is moved relative to the circumferential wall  22 . The interior plenum cavity  18  is divided into two volumes by the central valve plate  30   d,  a first interior volume, shown generally at  18   a  located between the central valve plate  30   d  and a valve seat  38  formed as part of the inlet port  14 , and a second interior volume, shown generally at  18   b  located between the central valve plate  30   d  and a back wall  12   a  of the housing  12 . 
         [0026]    There is also a connector, shown generally at  34 , which is in electrical communication with the actuator  26 . The actuator  26  is activated when a current is applied to the actuator  26  through the connector  34 . The direction which the plunger  28  travels to move the capnut  30  is controlled by the actuator  26 . The plunger  28  and capnut  30  are shown axially and radially fixed, however, in other embodiments, there is radial freedom provided to the capnut  30  which would compensate for axial misalignment, and the resulting travel path of the capnut  30 . When the plunger  28  travels in a first, or retract, direction, the capnut  30  moves towards the actuator  26  along an axis  36  that extends through the plunger  28 , and when the plunger  28  travels in a second, or extend, direction, the capnut  30  moves away from the actuator  26  along the axis  36 . When in the closed position, the capnut  30  is in contact with the valve seat  38 . The capnut  30  also includes an exterior cylindrical portion  30   c  which is in close sliding contact with interior of the circumferential wall  22 . The exterior cylindrical portion  30   c  fully obstructs the flow of air through the internal ports  24  when the capnut  30  is extended forward to the closed position. 
         [0027]    In  FIG. 3 , the capnut  30  is shown in the fully open position, where the internal ports  24  are completely unobstructed by the exterior cylindrical portion  30   c.  When in the open position, air flows from the inlet port  14 , into the interior plenum cavity  18 . A portion of the air flows into the first interior volume  18   a,  and a portion of the air flows into the second interior volume  18   b  because of the air passage through the apertures  32 . The air may also flow between the two interior volumes  18   a , 18   b  during the operation of the valve  10 , and may fluctuate based on the position of the capnut  30 . The portion of air that flows into each of the interior volumes  18   a , 18   b  depends on the position of the capnut  30 . Additionally, as the position of the capnut  30  changes, the size of each of the interior volumes  18   a , 18   b  changes as well. The air flows through the apertures  32  to provide a pressure balance on each side  30   a , 30   b  of the central valve plate  30 , regardless of the position of the central valve plate  30 . Placement of the internal ports  24  around the circumferential wall  22  is such to achieve a balanced radial air load on the capnut  30  (i.e., net side load force is substantially equal to zero). 
         [0028]    During operation, when the capnut  30  is moved away from the valve seat  38 , the air in the first interior volume  18   a  flows through the internal ports  24 . After the air passes through the internal ports  24 , a portion of the air flows directly into the outlet port  16 , and a portion of the air flows into the exterior plenum cavity  20 , and then into the outlet port  16 . The configuration of the internal ports  24  and the exterior plenum cavity  20  provides for a higher maximum flow capacity between the inlet port  14  and outlet port  16 , as opposed to a configuration where the internal ports  24  are formed as part of the circumferential wall  22  in close proximity to the outlet port  16 . 
         [0029]    The actuator  26  is controlled to move the sidegate capnut  30  between the open position as shown in  FIG. 3 , to the closed position, such that the capnut  30  is moved away from the actuator  26 , where the capnut  30  contacts the valve seat  38 , the internal ports  24  are blocked by the exterior cylindrical portion  30   c,  and the inlet port  14  is no longer in fluid communication with the outlet port  16 . When the capnut  30  is in contact with the valve seat  38 , the first interior volume  18   a  is essentially reduced to zero. However, there is still air in the second interior volume  18   b  because the air is still allowed to flow through the apertures  32  of the central valve plate  30   d  when the capnut  30  is in contact with the valve seat  38 . The capnut  30  is also capable of being selectively placed in any location between the fully open and closed positions to configure the exterior cylindrical portion  30   c  to partially obstruct the internal ports  24 , to control the flow of air between the inlet port  14  and outlet port  16 . 
         [0030]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.