Patent Publication Number: US-11028739-B2

Title: Dynamic locking and releasing cam lobe

Description:
BACKGROUND OF THE INVENTION 
     Numerous attempts to develop systems of variable valve actuation have focused either upon the rocker arm, or on the lifter. For instance, ways to lock components of multiple piece rocker arms together to allow operation of specific cam lobes (low lift, low duration, or high lift, high duration) on a single valve have been attempted. Others have used a rigid, collapsing follower to allow actuation of the connected valve in one mode, or allow the valve to remain closed in another. 
     These designs typically require the use of an additional spring return to ensure the follower maintains contact with the cam lobe as the cam engages the follower continuously. A simple system for allowing dynamic engagement or disengagement of a cam lobe on the camshaft would eliminate the need for additional hardware to control unneeded motion. 
     SUMMARY OF THE INVENTION 
     An embodiment of the present invention may therefore comprise: a cam driven reciprocating internal combustion engine comprising: a cylinder block defining a plurality of cylinders, each of the cylinders in mechanical communication with a respective cam driven intake valve and/or exhaust valve; a rotating camshaft in mechanical communication with at least one selectively disengagable cam lobe; the cam lobe that when mechanically coupled to the camshaft, controls the operation of the respective intake valve and/or the respective exhaust valve; at least one coupler that selectively couples and decouple: the rotational force of the camshaft to at least one respective cam lobe; at least one cam lobe that is rotationally disengaged and uncoupled from the rotation of the camshaft in a first mode thereby deactivating the respective valve, and the cam lobe that is rotationally engaged and coupled with respect to the rotation of the camshaft in a second mode thereby activating the respective valve; and, a controller that sends a signal to at least one of the couplers to rotationally disengage the respective valve during operation of the internal combustion engine. 
     An embodiment of the present invention may also comprise: a system for deactivating one or more valves of a reciprocating internal combustion engine during operation comprising: a rotating camshaft in mechanical communication with a plurality of cam lobes, each of the cam lobes that is mechanically coupled to, and controls the operation of, an intake valve or an exhaust valve associated with a respective cylinder of the internal combustion engine; at least one coupler that selectively couples the rotational force of the camshaft to at least one respective cam lobe; at least one cam lobe that is selectively rotationally disengaged and uncoupled from the rotation of the camshaft by the coupler in a first mode, thereby deactivating the respective valve from undergoing gas exchange during at least one cycle of the operation of the internal combustion engine, and at least one cam lobe that is rotationally engaged and coupled with respect to said rotation of the camshaft by the coupler in a second mode thereby activating the respective valve during at least one cycle of the operation of the internal combustion engine; and, a controller that sends a signal to at least one coupler to rotationally disengage the respective valve during operation of the internal combustion engine. 
     An embodiment of the present invention may also comprise: a method of deactivating one or more valves from undergoing gas exchange during the operation of an internal combustion engine comprising the steps: providing a cam driven reciprocating internal combustion engine comprising; a cylinder block defining a plurality of cylinders, each said cylinder in mechanical communication with a respective cam driven intake valve and exhaust valve; rotating a camshaft in mechanical communication with at least one selectively disengagable cam lobe thereby controlling the operation of said respective intake valve or said respective exhaust valve; providing at least one coupler that selectively couples and decouples the rotational three of the camshaft to at least one respective cam lobe; deactivating the respective valve by signaling at least one coupler to selectively rotationally disengage and uncouple the respective cam lobe from the rotation of the camshaft in a first mode; and, activating the respective valve by signaling at least one coupler to rotationally engage and couple with respect to the rotation of the camshaft in a second mode. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, 
         FIG. 1  illustrates an embodiment of a dynamic locking and releasing cam lobe system. 
         FIG. 2  illustrates an embodiment of a dynamic locking and releasing cam lobe system. 
         FIG. 3  illustrates an embodiment of an actuating dynamic locking and releasing cam lobe system. 
         FIG. 4  illustrates an embodiment of an actuating dynamic locking and releasing cam lobe system. 
         FIG. 5  illustrates an embodiment of an actuating dynamic locking and releasing cam lobe system. 
         FIG. 6  illustrates an exploded view of the same embodiment as  FIG. 5 . 
         FIG. 7  illustrates a cam lobe of an embodiment illustrated in  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While this invention is susceptible to embodiment in many different forms, it is shown in the drawings, and will be described herein in detail, specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not to be limited to the specific embodiments described. 
       FIG. 1  is an embodiment of a dynamic locking and releasing cam lobe system. In this embodiment, a system for allowing dynamic engagement or disengagement of the cam lobe on the camshaft is disclosed. As shown in  FIG. 1 , one or more of the lobes on a camshaft of the combustible engine or the like is adjustable to enable activation or deactivation of the intake and exhaust valves dynamically, e.g. without the need to replace or modify the camshaft, and without having to stop engine operation to achieve the activation or deactivation. As a common mechanism the camshaft is a mechanical device that converts rotary motion into linear motion. 
     In an internal combustion engine, the camshaft opens and closes intake and exhaust valves letting the air/fuel mixture into the cylinder and allowing the exhaust to exit. The camshaft includes cam lobes which lift the valves, wherein the greater the elevation of the lobe from its base circle, the higher the opening, which may allow more air/fuel into the engine and more exhaust out. The height of the lobe, or the distance it opens the valve, is known as the lift. The angular eccentricity of the lobe determines the angle relative to the crankshaft cycle the valves are kept open. This is known as the duration, and is typically given in degrees of crankshaft rotation. 
     In instances where a low output is desired, the ability to regulate and prevent gas exchange in certain cylinders every cycle may prove beneficial to the overall performance and efficiency of the system. One way this can be achieved is by utilizing a variable valve timing system where certain cylinders undergo gas exchange for example on every second, third or fourth cycle, or are infinitely adjustable to undergo gas exchange or be disabled at will. 
       FIG. 1  exemplifies a variable valve timing system  100  where a camshaft  110  contains a raised diameter  120  and a cam lobe  130  that may rotate independent of the camshaft  110 . This cam lobe  130  may be dynamically engaged and disengaged from the rotation of the camshaft  110  by utilizing an internal keyway  170  within the cam lobe  130  that integrates with a key  160  fixed to a slidable disk  140  positioned on the camshaft  110 . 
     The slidable disk  140  is positioned on the camshaft  100  to be fixed with respect to the rotation of the shaft, but is variable with respect to the axial positioning on the shaft. This is accomplished in this embodiment utilizing a race  150  that is fixed to the surface of the camshaft  100  and allows the axially slidable disk  140  to move a limited amount in the axial direction to engage and disengage the key  160  into, and out of the internal keyway  170  on the on the cam lobe  130 . The axially slidable disk  140  is constrained axially by the camshaft and rotationally by the race  150 . A small amount of translation in the axial direction is provided by the interaction between the race  150  and an axially oriented raceway  190  positioned through the axially slidable disk  140 . 
     In this manner, the cam lobe  110  has two distinct states of interaction with the valve. In one state, the axially slidable disk  140  is positioned as shown in  FIG. 1 , and the key  160  disengaged from the internal keyway  170 , whereby the cam lobe  130  is free and can be held stationary while the camshaft  110  rotates. The valve that this cam lobe operates on would then remain closed, preventing gas exchange through that valve. 
     In another state, the axially slidable disk  140  is positioned as shown in  FIG. 2 , and the key  160  is engaged with the internal keyway  170  thereby placing the cam lobe  130  in a locked position with respect to the camshaft  110 . This allows the engine to undergo gas exchange on all valves whose cam lobes are engaged with the camshaft  110 . 
     An axial slide engagement mechanism rotating with the camshaft may be utilized to engage and lock the cam lobe  130  with the camshaft  110  at the desired rotational angle. Such a mechanism may be electromagnetically or hydraulically actuated, with return springs to provide the opposite force requirement. This system may be engaged by default (inactivated) and disengaged when the activation force is applied, or vice versa. 
       FIG. 3  discloses such a mechanism where an activation actuator  210 , rotating with the camshaft  110  is able to transmit force to the axially slidable disk  140  via an actuator arm  220 . As depicted in  FIG. 3 , the actuator is in an inactive state, and the cam lobe  130  is independent and not rotating with the camshaft  110 . In this state, the cam lobe is not activated, and the valve(s) associated with this cam lobe  130  are inactive. This allows the particular valves fitted with this system to be inactivated very quickly and essentially at-will, in any engine cycle, and provides versatility in engine performance. The activation and timing of the activation actuator  210  and the clocking actuator  230  may be controlled by a controller  250 . This controller may utilize mechanical, hydraulic, electric or optical signals to be passed to the actuators. The controller may be microprocessor or logic driven and finely coordinated and tailored to the desired engine load or demand. 
       FIG. 4  depicts the mechanism of  FIG. 3  in an activated state, where the activation actuator  210 , rotating with the camshaft  110  transmits force to the axially slidable disk  140  via an actuator arm  220 . As depicted in  FIG. 4 , the cam lobe  130  is locked into place by the key  160  attached to the axially slidable disk  140  and fixes the rotation of the cam lobe  130  to the camshaft  110 . In this state, the cam lobe is activated and functioning as in a conventional engine, and the valve(s) associated with this cam lobe  110  are active. This allows the particular valves fitted with this system to be activated very quickly and essentially at-will, in any engine cycle. 
     Thus, a system for allowing dynamic engagement or disengagement of a cam lobe on the camshaft is accomplished, allowing alignment between the camshaft  110  and the cam lobe  130  with an engagement at a specified angular relationship. This permits the cam lobe  130  to be “parked” when disengaged so that it is not rotating, preferably at an angle that allows some rotation of the cam lobe as engagement occurs prior to contact with the follower/roller. The system, therefore, may be activated or deactivated on a cycle-by-cycle basis, so that it may have n cycles on, and m cycles off, where n and m are integers greater or equal to 0. 
     The activation mechanism (activation actuator  210  and actuator arm  220 ) may be an electromagnetic clutch, an hydraulic actuator or an activating spring that forces the key  160  attached to or part of the axially slidable disk  140  to engage with keyway  170  on cam lobe  130  when key  160  and keyway  170  are aligned, thus ensuring valve operation is synchronized with camshaft  110  rotation. This system provides synchronization of the disengagement of the cam lobe  130  from the camshaft  110  and utilizes an arresting mechanism that prevents the rotation of the cam lobe when disengaged. Synchronization of the removal of the arresting mechanism may be accomplished simultaneous with the engagement of the cam lobe  130  with the camshaft  110 . 
     A retention mechanism  240  may be utilized to hold or regulate the position of the cam lobe  130  at a particular position when it is inactivated or in a non-rotating state while camshaft  110  rotates, Such a mechanism may be flexible enough that re-engagement of the key  160  on the axially slidable disk  140  with keyway  170  on cam lobe  130  would allow essentially unhindered rotation of cam lobe  130  with camshaft  110 . This would allow clocking of the relation between the key  160  and the keyway  170  providing greater precision and speed of the engagement. 
     The clocking mechanism (retention mechanism  240  may be activated by a clocking actuator  230 ) may also be an electromagnetic clutch, an hydraulic actuator or an activating spring that forces retention mechanism  240  to engage with the cam lobe  130  when the clocking actuator  230  is activated, thus ensuring that the cam lobe  130  and particularly the internal keyway  170  is positioned for engagement with the key  160  thereby assisting in the synchronization of the rotation of the axially slidable disk  140  with the cam lobe  130 . 
     By example, an internal combustion engine (regardless of fuel type e.g., gasoline, diesel, or the like) utilizing a conventional cam driven reciprocating design may benefit from the selective removal, deactivation or interruption of one or a number of valves. When a vehicle is operating at low speed, low load, at idle conditions or other inefficient circumstances for a fully displaced internal combustion engine, deactivation of cylinders may improve the fuel economy. For instance, a vehicle with an 8 cylinder engine may receive benefit of increased fuel economy if only 4 cylinders of the internal combustion engine are operating during relatively low torque operating conditions by reducing throttling losses. The deactivated cylinders may also prevent gas exchange across the respective intake and exhaust valves, thereby reducing losses by enabling the engine to operate at a higher intake manifold pressure. By deactivating for instance, 4 of the cylinders during low torque demand modes of engine operation, the efficiency of the engine may be improved. Typically it may be preferred that alternating cylinders within the firing sequence of the engine be deactivated so that the engine balance is maintained. 
     The versatility of the above detailed system allows for a wide variety of deactivation schemes that can be tailored to specific engine load situations. These deactivation schemes and their selection based upon specific engine load situations may be controlled and implemented by a digital computer or programmable chips to selectively provide signals to control the operation of the actuators. Thus, an automated system that provides a dynamic locking and releasing cam lobe may be realized in the disclosed embodiments. 
     In an alternative embodiment, aligned pins are an alternative to a key and keyway, Aligned cylindrical cavities in both the cam lobe  130  and a feature fixed to the camshaft may be utilized so that pins may be engaged or disengaged by a combination of cylindrical pins and an oil supply controlled by a solenoid system. Such an oil supply might be introduced through the camshaft  110  and enter the camshaft feature. For instance, the actuator  210  may be accomplished by having oil routed through the camshaft  110  with separate drillings, and solenoid actuated, so that the actuator arm  220  is engaged in this manner. A sandwich type feature may be introduced on the camshaft  110  to ensure the cam lobe  130  does not move axially when the activation or spring force is applied to engage or disengage. It is desired that the cam lobe  130  not wander axially when disengaged, One way of ensuring this doesn&#39;t happen is to have the race  190  extend as far as cam lobe  130 . The cam lobe  130  may require a locking device for appropriate orientation when disengaged to allow maximum, or near maximum rotation angle for secure engagement to occur prior to valve actuation. 
     This is because it is undesirable to have the cam lobe  130  resting against the follower when disengaged, since there is a potential for a mechanical shock to be realized when the cam lobe  130  is engaged with the camshaft. Additionally, the cam lobe  130 , may not engage on the first attempt, especially if the signal to engage occurs when the key  160  and internal keyway  170  are nearly aligned. In this instance, there may be partial actuation of the valve, but not enough to achieve full operation. By allowing as much angular separation as possible between the attempt to engage the cam lobe  130  and the angle at which the cam lobe  130  operates the valve, a greater safety margin for proper valve operation is established. 
       FIG. 5  illustrates an embodiment of an actuating dynamic locking and releasing cam lobe system. A cam shaft  110  is shown having a grooved portion  111 . Keyrings  112  and  114  have keyring keys  115  and  116  respectively that engage groove  111 . Keyrings  112  and  114  may fully encircle the cam shaft  110 . Keyrings  112  and  114  are rotationally locked with cam shaft  110  through keys  115  and  116  respectively, but are axially slidable. Each key  115 ,  116  is engageable with cam lobe keyway  132 . Keyrings  112 ,  114  also have actuation forks  117 ,  118  respectively that transmit external forces to said keyrings to allow axial movement. Actuation forks  117  and  118  slide along actuation fork rods  147  and  148  respectively. Typically actuation forks  117  and  118  will move in opposite directions to engage or disengage cam lobe  130  in a symmetric fashion. 
     As shown in  FIG. 5 , keyrings  112 ,  114  are shown for engagement with a single cam lobe. It is understood that there may be more cam lobes being utilized with a particular cam shaft, and thus a corresponding increase in the number of keyrings and actuation forks. When a keyring  112 ,  114  moves to engage a cam lobe  130  via the key  115 ,  116 , said keys will engage keyway  132  of cam lobe  130  to lock cam lobe  130  to cam shaft  110  in a specific angular orientation. Keyrings  112 ,  114  may be engaged and disengaged once per cam shaft rotation if desired, or one or more times per multiple cam shaft rotations. 
       FIG. 6  illustrates an exploded view of an embodiment illustrated in  FIG. 5 . Keyrings  112 ,  114  and cam lobe  130  have been moved axially to disclose further features of the cam lobe engagement and disengagement system. Actuation forks  117 ,  118  and actuation fork rods  147 ,  148  have been moved axially and laterally to display further features. Actuation forks  117 ,  118  have tongues  127 ,  128  respectively that engage continuously with grooves  137 ,  138  in keyrings  112 ,  114  respectively. This engagement allows keyrings  112 ,  114  to rotate permanently with cam shaft  110  while permitting actuation forks  117 ,  118  to apply external force to keyrings  112 ,  114 , allowing axial movement of said keyrings when desired. Cam lobe  130  has an internal groove  133  that engages pin  151  on cam shaft  110 . Pin  151  is installed via hole  134  on the base circle of cam lobe  130 . Typically two or more pins  151  will be inserted into cam shaft  110  to prevent possible axial movement of cam lobe  130  if keyway  132  is wider than the diameter of pin  151 . Pins  151  may be fasteners that are threaded into cam shaft  130 , or pins that are pressed in. 
       FIG. 7  illustrates a cam lobe of an embodiment illustrated in  FIG. 5 . A cam lobe  130  has a keyway  132  with a tapered ramp  131  on each side of said cam lobe that leads to said keyway. Keys  115 ,  116  on keyrings  112 ,  114  may be tapered to engage tapered ramp  131  to provide greater surface area when actuator forks  117 ,  118  are applying force to engage said keys with said cam lobe keyway. 
     As shown in the figures, and particularly  FIG. 5 , a mechanical mechanism may be used to attach to actuation forks  117 ,  118 . The physical connection between said actuation forks and keyrings  112 ,  114  respectively allows the keyrings to be moved in opposite directions simultaneously. For instance, electromagnetic solenoids, or pneumatic actuators or hydraulic actuators may be used to move the keyrings  112 ,  114  (and thus engagement keys  115 ,  116  respectively) via actuation forks  117 ,  118  to and from the engaged position in the keyway  132  of the cam lobe  130 . Accordingly, the actuation mechanism may be connected to a hydraulic, pneumatic or electromagnetic activation mechanism that allows movement of the keyrings  115 ,  116 . Such an actuation mechanism may apply force in both directions, or may also use a spring return system so that actuation only requires activation in one direction. 
     The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.