Abstract:
A device and method for double actuating, by pressure differential, a valve of a combustion chamber of an internal combustion engine, wherein the double actuating device comprises an actuator piston displaceably arranged in an actuator cylinder between two chambers of inversely varying volume, mechanically attached to the stem of said valve. The valves are double actuated independently of engine operation, the method allowing for variation in timing, duration, and lift under an electronically controlled fluid circuit, using alterable constants to allow for modifiable operating modes, also allowing reprogramming of said electronics to provide for in-place upgrades.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Provisional application No. 61/637,207 filed Apr. 23, 2012. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
     Patent Citations 
       [0000]    
       
         U.S. Pat. No. 8,056,515 B2 Nov. 15, 2011 Mats Hedman Assignee: Cargine Engineering 
         Method and device for the operation of a valve of the combustion chamber . . . . 
         U.S. Pat. No. 7,984,701 Jul. 26, 2011 Re Fiorentin et al. Assignee: Fiat Auto Spa 
         Device for controlling the movement of a valve, . . . , of an internal combustion engine. 
         EP1770247 A2 Sep. 28, 2005 Chiavazzo, Dell&#39;Orto, et al. 
         Electro-hydraulic variable valve actuator and method to control valves . . . . 
         20050188928 Sep. 1, 2005 Sedda, Emmanuel et al. 
         Electromagnetic valve actuating device for an internal combustion engine. 
         U.S. Pat. No. 6,315,265 B1 Nov. 13, 2001 Adler et al. 
         Variable valve timing actuator. 
       
     
         [0013]    The present invention relates to a device and method for the actuation of a valve of a combustion chamber of an internal combustion engine, independently of mechanical movement within the engine and without a camshaft. 
         [0014]    The majority of existing internal combustion engine designs rely on mechanical means to open and close intake and exhaust valves. Other types of actuators have been proposed for years based on the concept that variable valve actuation independent of engine operation could overcome inherent compromises and inefficiencies in cam driven (mechanical) operation. The present invention addresses these compromises in engine operations and offers increased flexibility for the engine designer and increased efficiency in operation. 
         [0015]    Inherent inflexibility in valve train operation has usually meant that completely different parts had to be installed to change engine valve operation. Some benefits of variable valve timing and lift are seen in mechanical designs that provide variable mechanical actuation determined by load or engine speed. These have become popular but still present a very limited option (usually 2 or 3 configurations) compared to actuating the valves independent of engine operation. The present invention provides a broader selection of operating parameters approaching a continuously variable design. 
         [0016]    Other inventions in the field include electromechanical, hydraulic and pneumatic systems, although these have usually been supplemented by mechanical return springs which retain many of the other limitations of the primarily mechanical designs. These limitations include high stresses at low rpm in order to meet high rpm needs, inherent harmonic oscillations that can cause valve ‘float’ under some conditions, elastic failure in which springs ‘relax’ over time and perform less well with age—regardless of usage. A pneumatic valve return system was adopted for Formula I racing cars which still relied on mechanical (cam) valve activation and suffered from failure modes not seen in other systems. The present invention addresses these limitations while providing unique upgrade and customization paths. 
       BRIEF SUMMARY OF THE INVENTION 
       [0017]    The present invention is directed to a valve actuator for controlling the movement of a valve of an internal combustion engine, the actuation device comprising: a double acting actuator piston or diaphragm, contained within a cylinder closed at each end so as to form two chambers of inversely variable volume, mechanically affixed to the valve stem so as to control the position of the valve via chamber-pressure differential, directly or through a lever arm, and an electronically controlled fluid circuit for controlling the inlet and outlet of pressurized fluid to both chambers formed by the actuator piston or diaphragm and cylinder. The method for controlling the movement of the actuator piston by controlling the pressures and timing of the pressure changes will permit variable valve actuation: timing, duration, and lift. The method of controlling valve actuation with programmable variables will permit engine designers and tuners to tailor engine performance specifications while providing a convenient method for maintenance upgrades. These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0018]    Further characteristic features and advantages of the invention are set out in the following detailed description, given purely by way of non-limiting example and made with reference to the accompanying drawings, in which: 
           [0019]      FIG. 1  shows a diagrammatic view in perspective of an internal combustion engine valve and stem associated with one embodiment of a valve actuating device of the present invention, the valve being in the closed position. 
           [0020]      FIG. 2  shows a diagrammatic view in elevation of an internal combustion engine valve and stem associated with one embodiment of a valve actuating device of the present invention, the valve being in the open position. 
           [0021]      FIG. 3  shows double vertical axis Cartesian diagrams as a function of piston position of one version of the curves of the lift of an intake and exhaust valve associated with a valve actuating device of the present invention under two different hypothetical operating conditions. 
           [0022]      FIG. 4  shows a tabular representation of one version of the table of constants stored by the electronic control circuit and a tabular representation of one version of the calculated values used to control operation of a valve actuator of the present invention. 
           [0023]      FIGS. 5A and 5B  show tabular representations of one version of the pressure settings vs. engine rpm calculations for programming regulators of a valve actuator system of the present invention for an intake valve actuator ( 5 A) and an exhaust valve actuator ( 5 B) based on supposed input required forces as examples of the dynamic control settings the system is designed to use. 
           [0024]      FIG. 6  shows a schematic diagram of one version of a fluid circuit for a system of valve actuators of the present invention as applied to one cylinder of an internal combustion engine of one or more cylinders. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    In referring to the diagrams, the following terms will be used for brevity and clarity but are not meant to limit the scope of the claims: fluid is a liquid or gas such as hydraulic fluid or air, a spool is a flow control device such as a poppet valve or pneumatic spool or hydraulic spool for communicating fluid flow and pressure, a check valve is a one-way check valve or an adjustable pressure regulating device in combination with a one-way check valve, a piston is a piston or a diaphragm, a valve is an intake or exhaust valve of a combustion chamber of an internal combustion engine. 
         [0026]    Referring to  FIGS. 1 ,  2 , and  6 , the present invention pertains to a device for controlling the movement of a valve  15 , which allows intake or exhaust flow of a combustion chamber through runner  15   a,  with a double acting actuator piston  11 . A series of flow control devices, including solenoid actuated spools  20  &amp;  21  used to communicate fluid to the upper chamber  13  and check valves  22  &amp;  23  (or as an alternate embodiment, solenoid actuated spools) used to communicate compressible fluid to the lower chamber  14 , coordinated so as to operate the valve  15  through chamber-pressure differential. In the primary embodiment both chambers  13  &amp;  14  receive pressure regulated compressed air. 
         [0027]    The double acting actuator piston  11  is displaceably arranged within an actuator cylinder  12  so as to separate chambers  13  &amp;  14 , and is manufactured such that leakage between the opposing chambers  13  &amp;  14  can be controlled (sealed) while allowing the necessary movement to double-actuate (open and close) the valve  15 . The actuator piston  11  is mechanically attached, primarily directly or alternately through a lever arm (commonly known as a rocker arm), to the valve stem  15   a  so as to move the valve  15  within the valve guide  16 . 
         [0028]    In construction, the actuator cylinder  12  and chambers  13  &amp;  14  are formed in a housing that may be a cast-in-place part of the engine head or mechanically fastened in place. The housing has an inlet  16  and an outlet  17  for the upper chamber  13  and an inlet  18  and an outlet  19  for the lower chamber  14  either as part of the housing, within end-cap  10 , or a combination. In addition, the housing and/or end cap(s) may provide for mounting pressure and/or flow control devices as described below, and connecting supply  20   b  and exhaust  21   b  manifolds. In an alternate embodiment, the chambers are connected to auxiliary chambers or manifolds to provide for pressure storage. 
         [0029]    The upper chamber inlet  16  pressure control consists of two spools  20 , which function as an ‘and gate’, actuated independently by bistable electronically controlled solenoids  20   a.  As a alternate embodiments, the upper chamber inlet  16  pressure control can be of the spring return type and/or a single spool actuated by an electronically controlled solenoid. The upper chamber inlet pressure is supplied from a pressure regulated supply manifold  20   b  in the preferred embodiment. 
         [0030]    The upper chamber outlet  17  pressure relief consists of a single spool  21  moved by an electronically actuated solenoid  21   a . Alternately, the upper chamber outlet  17  pressure relief can be two spools, which function as an ‘and gate’, actuated independently by bistable electronically controlled solenoids. The upper chamber outlet pressure is exhausted to a pressure regulated exhaust manifold  21   b  in the preferred embodiment. 
         [0031]    The lower chamber inlet  18  pressure control consists of a check valve  22 , connected to the pressure regulated supply manifold  22   b  (alternately, a separate pressure regulator and/or manifold may be used). Alternately, the lower chamber inlet  18  pressure control can be a single spool actuated by an electronically controlled solenoid (not shown). 
         [0032]    The lower chamber outlet  19  pressure relief consists of a check valve  23 , connected to the pressure regulated exhaust manifold  23   b,  to the atmosphere, or to other suitable outlet. Alternately, the lower chamber outlet  19  pressure relief can be a single valve or spool actuated by an electronically controlled solenoid. 
         [0033]    As shown in  FIG. 6 , the expected use of the present invention is a coordinated system of more than one actuator device, each actuator device mechanically connected to an intake valve  15  or an exhaust valve  15  of an internal combustion engine, one device per valve  15 . Alternately, it is possible to actuate more than one valve  15  for each actuator through the use of lever arms or other mechanical connections. 
         [0034]    The bistable solenoids  20   a  and  21  a are triggered by an electronic control circuit consisting of a microprocessor, various inputs and sensors, shift registers (optional for small systems), H-bridge controller circuits or ICs and the connectors, power supplies, switches, relays, and the necessary circuitry and parts to connect, regulate, and protect these components. To implement the interactive features of a programmable system, additional interface connections (OBDII, USB, or equivalent, or wireless) are required, as is a program to allow programming, configuring, and I/O with, the microprocessor. 
         [0035]    Referring to  FIGS. 3 and 4 , in the primary embodiment each pressure regulator and solenoid is controlled electronically so that the timing and extent of valve  15  movement is adjustable to meet engine operating parameters by a combination of pressure settings and timing signals. Varying the pressure in the supply  20   b  and exhaust  21   b  manifolds and of the operating pressure of one-way check valves  22  and  23  (by the pressure settings of manifold  22   b  and  23   b ) enables the valve  15  to be subjected to (relatively) lower forces at low rpm and only subjected to higher forces at high rpm. 
         [0036]    Referring to  FIGS. 5A and 5B , the method of controlling valve  15  movement relies on the cycle of pressures applied to the actuator piston  11  by differential chamber pressure, sample calculations used to develop these pressure settings and forces resulting therefrom are shown. The upper chamber high pressure provides valve  15  opening force, net of lower chamber low-through-high pressure (transitioning as the fluid is compressed) and then hold open force. The lower chamber high pressure provides valve  15  return force, net of upper chamber low pressure (once upper chamber high pressure is released). The lower chamber low pressure provides valve seat force, net of upper chamber low pressure. In summary, the lower chamber acts as a pneumatic spring, while varying pressure in the upper chamber alternately compresses and releases this pneumatic spring. 
         [0037]    More specifically, the upper chamber inlet spools  20  can be controlled through an ‘and gate’ of two independently operated bistable solenoids  20   a  to independently and variably control valve  15  timing, duration and lift, using the following preferred method: Valve  15  timing and duration are controlled by the timing of the triggering of the inlet solenoid (pair)  20   a  and outlet solenoid  21   a  of the upper chamber  13 . Signal processing and inertial movement delays within the system—typically on the order of a few milliseconds, as well as engine crankshaft angle and rotational speed, are used to calculate solenoid  20   a  &amp;  20   b  control trigger signal generation. Discrete signals to the pair of inlet solenoids  20   a  control charge-pulse duration (therefore volume and pressure) and offset signal timing can control valve  15  lift. For required charge-pulse durations equal to or longer than solenoid movement duration (on the order of 5 ms), the primary solenoid  20   a  (currently ‘closed’) is triggered with or prior to the secondary solenoid  20   a  (currently ‘open’). For shorter required charge-pulse durations (and lower valve  15  lift), the secondary solenoid  20   a  is triggered prior to the primary solenoid  20   a,  thus allowing shortening of the charge-pulse duration to as short as the signal switching repeatability limits (on the order of 0.5 ms). In the preferred embodiment the upper chamber outlet spool  21  can be accurately controlled by a single solenoid  21   a  since the outlet  17  bleed-pulse duration is not as critical as the inlet  16  charge-pulse duration and the outlet pressure is suitably controlled by the exhaust manifold  21   b,  valve  15  closure ‘lift’ being constant 0. 
         [0038]    The adjustment to the lower chamber low pressure is through a one-way check valve  22 , in which supply pressure can pass through the one-way check valve  22  when the lower chamber low pressure falls below a determined level. The adjustment to the lower chamber high pressure is through a one-way check valve  23  when the lower chamber high pressure exceeds a determined level. The preferred embodiment is for both of the one-way check valves  22  &amp;  23  to be attached to pressure adjustable manifolds, thereby allowing dynamic adjustment during engine operation. 
         [0039]    The timing of valve  15  operation can be altered to enable smooth low rpm operation (later intake pulse and decreased valve overlap) and efficient high rpm operation (earlier intake pulse and increased valve overlap) with an almost continuous transition. The duration and lift of valve  15  operation can be altered to meet low demand (short duration, small lift) and high demand (long duration, large lift) with an almost continuous transition. In addition, unique combinations are available with this system: some valves  15  (and thereby, combined with temporary fuel and possibly ignition spark cutout, some combustion chambers) can be temporarily non-actuated, allowing the engine to behave as one of smaller displacement operating at increased air-flow (higher efficiency during low demand operation); some valves  15  timing can be staggered within an engine cylinder to promote fuel-air swirl; some valves  15  can be actuated or non-actuated to allow engine cylinders to behave as two valve  15  or four valve  15  arrangements to meet varying operating parameters. An increase in efficiency is expected due to removal of the throttle plate, varying valve duration and lift to control fuel-air induction, thereby reducing pumping losses through the engine. 
         [0040]    An orifice restricted upper chamber exhaust muffler (not shown) may be incorporated to provide a ‘soft seat’ for valve  15  closure. Mechanical methods of softening the impact (so called ‘bump stops’) at piston  11  travel limits may be used as well. Although the primary embodiment uses both of these braking methods to reduce noise and mechanical wear, some (or all) applications may function normally without this ‘braking’ or may use a substitute method. 
         [0041]    Referring to  FIGS. 3 ,  4 ,  5 A and  5 B, a unique benefit of the primary embodiment is the flexibility for maintenance and upgrade programming of the electronic control system. This method will allow manufacturers and tuners to tailor engines for different operating conditions and demands and update in-place systems as changes are specified without changing hardware in many instances. A layered software system design is used wherein a main program determines overall behavior characteristics of the system and a parameter table is used to ‘tune’ the system. Different ‘modes’ can be programmed to allow the driver to select from a set of engine performance behaviors (ex: ‘economy’, ‘city’, ‘sport’, ‘towing’, ‘valet’, etc.). 
         [0042]    The preferred embodiment uses a continuously replenished pneumatic (air) supply and exhaust system for speed of operation and low cost construction. One alternate embodiment could use hydraulic fluid as the upper chamber  13  circuit fluid, although this would require changes to the seals and pressure system, and the use of a recovery and storage system. 
         [0043]    A limitation of the present invention is leak-down over time. Although some leak-down is unavoidable and easily dealt with, a seal failure or engine start after a long delay could lead to engine damage due to piston-valve interference. There are two strategies for dealing with this potential: Primarily, the device can be restricted to use in non-interference engines. The decrease in power and efficiency can be more than recouped by turbo-charging the engine intake system. Since this is common and inherently increases efficiency it is the preferred embodiment. Secondly, the system can incorporate safety pumps and latches to prevent piston-valve strike under normal operation, including startup. For system reliability it is anticipated that some form of monitoring system, most likely one or more pressure sensors, will be incorporated into the electronic and/or fluid circuits. For non-interference engines, a maintenance mode may be programmed that when selected will allow the valves to operate as if the crankshaft was turning in order to check for proper operation. 
         [0044]    The present invention may provide all or some of the benefits described above, depending on the specifications (both mechanical and electronic) as implemented. Not all of the benefits will be realized for all applications and failure to provide a desired benefit in any particular application or combination of applications should not be interpreted to limit the scope of the claims made. 
         [0045]    Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, it is understood that other alternates and equivalents of each of the above embodiments are within the scope of the invention. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained therein. Accordingly, all such modifications are intended to be included within the scope of the invention as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures.