MXPA96001186A - Valv control system - Google Patents

Abstract

The present invention relates to a valve control system for an internal combustion engine that includes a cylinder head, a pipette valve, and a camshaft having a cam lobe formed therein, said control system comprising means in said cylinder head defining a pivot point, a first oscillating arm mounted for rotation about said pivot point and engageable with said pipette valve, a second oscillating arm mounted for rotation relative to said first oscillating arm and engageable with said cam lobe: means for polarizing said first oscillating arm to be connected to said pivot point and said second oscillating arm to be connected to said cam lobe, and means for selectively interconnecting said first and second oscillating arms for unison movement about said point. of pivot in response to a force applied by said cam lobe to said second oscillating arm said means that polarize said first oscillating arm in relation to said pivot point and said second oscillating arm in connection with said cam lobe comprise a spring acting between said first and second oscillating arms, characterized by: (a) said first arm The oscillating member comprises a first elongated arm member having a valve contact element formed at one of its ends, a first spring receiving surface formed at its opposite end, and a first pivot bearing member formed between said valve contact element. valve and said spring receiving surface, said second swing arm comprises a second elongated arm member having a contact surface formed at one of its ends, a second spring receiving surface formed at its opposite end, a second bearing element pivot formed between said contact surface and said resorption receiving surface

Description

VALVE CONTROL SYSTEM Description The present invention relates to valve operating apparatuses for an internal combustion engine and, more particularly, to apparatuses for varying the operating characteristics of intake or exhaust valves in such engines during various operating modes of the engine. ^^ Variable valve control systems for multi-valve engines are well known in the art where the intake and / or exhaust valves can be selectively actuated or driven to selected lifting profiles. One known system is shown in the patent of the United States No. 4,151,817, which describes a primary oscillating arm element engageable with a first cam profile, ^ a variable secondary oscillating arm element with a second cam profile, and means for interconnecting or locking the primary and secondary oscillating arm elements. It is an object of the present invention to incorporate the lockable swing arm concept of the above system into a system that is specifically operable to selectively drive or deactivate a motor valve. It is an additional objective to provide such a system that is less expensive to manufacture, has improved response, requires less operating force and has a longer service life than prior art systems. There is a particular problem in the prior art systems operating in a valve train that incorporates hydraulic whip adjusters as means must be provided to prevent the whip adjuster from expanding too much or "pumping" when the valve is in its inactive mode and there is essentially no resistance force applied to the spring of the valve. In prior art systems, it has been necessary to provide an auxiliary contact surface on the structure of the swing arm that is maintained in engagement with a base circle cam portion formed in the cam shaft. The present invention satisfies the above objects and solves the above problems by providing a lockable oscillating arm assembly that includes an internal oscillating arm having a roller that contacts the cam; an external oscillating arm that links the valve, the internal and external arms being in nested relationship with each other and in pivotal contact with the output piston of a stationary whip adjuster; and a sliding bolt member that is movable between an active position where the inner and outer arms are effectively locked together and operable to operate the valve, and an inactive position where the inner and outer arms are free to move. one in relation to the other and the valve is not actuated. The assembly also includes polarization means that act between the internal and external arms to polarize the internal arm with the cam and with the external arm and the external arm with the plunger of the whip adjuster. In unlocked mode, the polarization means prevent the whip adjuster from pumping, loading the external arm against the plunger. A positive stop is provided to limit the leakage of the adjuster from the downward bias caused by the loading of the biasing means against the plunger of the whip adjuster in the unlocked mode. Other objects and advantages of the invention will be apparent from the following description, taken in conjunction with the accompanying drawings, wherein: Figure 1 is a partial plan view of the invention; ^^ Figure 2 is a sectional view taken along line 2-2 of Figure 1; Figure 3 is a plan view of a first oscillating arm of the invention; Figure 4 is a sectional view taken along line 4-4 of Figure 3; Figure 5 is a plan view of a second oscillating arm of the invention; Üfr The f? 9"ura 6 is a sectional view taken along line 6-6 of Fig. 5; and Figure 7 is a schematic representation of the invention, illustrating the forces acting on it. Referring mainly to Figure 2, there is illustrated a portion of the cylinder head 10 of an internal combustion engine of the upper head cam type, which incorporates the valve control system 12 of the invention. As illustrated herein, the control system 12 ^ ^ is of the type that is particularly adapted to selectively actuate or deactivate a motor valve and comprises an oscillating arm assembly 14 that is capable of being switched between an active mode where it is operable to open the valve, and an inactive mode where the valve is not open; and an actuator assembly 16 that is operable to change the oscillating arm assembly between its active and inactive modes. The oscillating arm assembly 14 comprises an inner arm assembly 18 which is engageable with the valve actuator cam 20 of the engine, an external arm 22 which is engageable with a pipette valve 24 which is normally kept closed by a spring 25, a polarization spring 26 acting between the inner and outer arms to polarize the inner arm in engagement with the cam 20 and the outer arm in engagement with the plunger 30 of a stationary whip adjuster 32, and a bolt member 28 which is received slidable on the * ttr external arm and that it is effective to close the internal and external arms together to define the active mode of the control system or to unlock them to define the inactive mode. In the preferred embodiment of the invention, the outer arm 22 is pivotally mounted on the plunger 30 and the inner arm 18 is pivotally mounted on the external arm 22. The construction and function of the whip adjuster 32 are well known and not they will be described in detail herein. To provide a better understanding of the relationship 9 between the internal and external swing arms, reference will be made to the details of these components in Figures 3-6. Referring to Figures 3 and 4, the inner arm 18 is preferably a patterned structure, generally U-shaped in plan, having spaced wall sections 34 and 36, a contact element 38 at the base of the U, and a central dorsal section 40. The dorsal section 40 defines the pivot point of the arm in the form of a portion of ^? pin 42 contacting the outer arm, as will be described later, and a spring retaining member 44. Aligned perforations 46 are formed in the walls 34 and 36 to receive the shaft of a needle roller assembly 48 (see figure 2). As will be described later in greater detail, the contact element 38 defines a bolt surface that interacts with the external arm 22 and the bolt member 28. A pair of outwardly extending stops 50, 51 are formed in the walls 34, 36 to limit the relative movement between the internal and external arms. Referring to Figures 5 and 6, the outer arm 22 is a generally rectangular plan view member having spaced side walls 53 and 54 and converging end portions 56 and 58, the end portion 56 defining a retention member of spring 60, and the end portion 58 defining a valve contact pad 62. A frame member 64 is formed between the walls 52 and 54 ^ F and defines a pin portion 66 that is received between the pin portion 42 of the internal arm and the plunger of the whip adjuster 30 when the arms are assembled. The walls 52 and 54 are grooved at 68 and 70 to receive the bolt member 28. Referring again to Figure 2, when assembling the inner and outer arms are nested together with the back section 40 of the inner arm 18 received. on the frame element 64 of the external arm 22. The needle roller assembly 48 is received between the walls 34, 36 of the inner arm with the roller shaft having a sliding fit within the perforations 46. With the inner arm being received between the walls 52, 54 of the outer arm, the shaft 76 is always in contact with the walls during operation, such that positive retention means such as staking are not required to retain the needle roller assembly.

™ When the assembled swing arms are installed in the motor, the pin portion 66 of the external arm 22 is positioned on the plunger 30 of the whip adjuster 32, which places the roller assembly 48 of the inner arm 18 in contact with the cam 20 and the contact pad 62 of the outer arm 22 in contact with the valve 24. When the spring 26 is positioned on the detents 44 and 60 between the internal and external arms, the internal arm 18 is polarized to be linked to the cam 20 (via roller 48) and outer arm 22 is biased to bond with valve 24, the angular position of oscillating arm assembly 14 about the longitudinal axis of the whip adjuster being held by the end of the valve stem 24 caught between the walls of the converging end portion 58 of the external arm 22. The control system 12 is switched between its active and inactive modes by means of the bolt member 28. In the form In the embodiment shown, the bolt is in the form of a plate that is mounted on the external arm 22 and is engageable with the contact element 38 of the internal arm. The bolt member 28 comprises a first flat plate element 78 which slides along the upper surface of the outer arm and which has a central region 80 which is engageable with the contact element 38 of the inner arm, and a pair of elements axially extending finger 82 and 84 that straddle the inner arm and are receivable within the slots 68 and 70 of the ~? external arm. The bolt member is biased to its locked position and held in position on the outer arm by means of tongues 86 and 88 that partially surround the end 58 of the outer arm. As illustrated in Figures 1 and 2, the bolt member is shown in its active position or linked to the central region 80 linked by the inner arm. In this position, when the cam 20 rotates through the broken line position of Figure 2, the force of the cam 20 on the roller _ 48 is transmitted to the external arm 22 through the latch 28 and * «to the valve 24, moving the valve to its open position. To change the assembly from its active mode to its inactive mode, the bolt member 28 is moved to the right, as illustrated in Figure 2, by means of the actuator assembly 16 to slide the bolt member out of engagement with the arm. internal. With the bolt disengaged, the force of the cam against the inner arm is not transmitted to the external arm, and the valve remains in its closed position. In the illustrated embodiment, the actuator assembly is shown somewhat schematically as a variety of linear actuator arrays can be used to change the bolt member 28, and the actual arrangement employed will depend on the space and mounting limitations associated with an engine in particular in which the system is installed. As shown herein, the assembly comprises a clamp member 90 suitably attached to the motor, a solenoid 92 attached to the clamp, a drive rod 94 that is pivotally mounted to the clamp at 96 and slidably received. within the bolt member 28 and linked by the outlet member 98 of the solenoid, and a compression spring 99 acting between the solenoid 92 and the rod 94 to polarize the bolt member to a normally linked position. To accommodate the movement of the valve, the rod 96 is received through a spherical plug member formed in the bolt member, allowing the bolt member to slide along the rod as it moves between the closed valve position shown in FIG. the complete line and the open valve position shown in broken line without undue lash between the actuator and the bolt. Figure 7 is a schematic representation of the valve control system 12 illustrating how the system overcomes the pumping problems of the whip adjuster in the unlocked mode without requiring circle contact elements Base and similar. The pumping of the whip adjuster is a main concern to maintain proper functioning of the control system. Excessive pumping when the inner arm is linked to the base circle of cam 20 will affect both the locking and unlocking functions. In the locked mode, pumping will cause the contact element 38 of the inner arm to be loaded against the bolt member 28, not allowing the bolt to disengage. In the unlocked mode, the pump will cause the element 28 to be under the bolt, not allowing the bolt to re-engage. A locking condition occurs when the upward force of the plunger 30 exceeds the downward load of the internal swing arm in the base circle. The force of the lash adjuster 32 is the sum of the spring load of the plunger and the force of the high pressure oil fed to the whiplash adjuster acting on the projected area of the plunger, which attempts to push the plunger out of the body, the oil pressure ^ P "being the largest contributor As the external arm and the plunger move axially upward, the inner arm 18 is also pushed upwards As the cam 20 prevents the roller 48 from moving upwards, the arm The inner member is forced to pivot about the axis of the roller as the plunger moves upwards, compressing the spring 26, increasing the load between the inner and outer arms, resulting in a static condition or until the plunger reaches its stoppage of displacement. ^ & • T-in. In the form of a talk to the pumping condition, the leak occurs.This occurs when the load of the spring 26 exceeds that of the whiplash adjuster. 50 and 51, which link the walls 52 and 54 of the external arm. When the spring 26 applies a load to the stops, the load is shared between the whip adjuster and the stops until a static condition is again reached. In the following equations, Fl is the force applied by the piston 30 of the whip adjuster to the swing arm assembly, F2 is the force of the spring 26 acting between the internal and external swing arms, F3 is the force of the cam 20 against the roller 48, F4 is the force of reaction against the tip of the valve, F5 is the force between the internal and external arms at stops 50 and 51, and F6 is the force acting between the internal and external arms at the contact of the plunger. From the drawings, it can be seen that the forces acting JPfcr on the system act around the pivot point P defined by the pin element 66 of the external arm. The spring force F2 acting on the point P applies a force against the inner arm 18 which keeps the roller 48 in contact with the cam 20 when the cam is in its base circle and which resists the cam force F3 by turning the cam to its active or open valve position. The force F2 also applies a force to the outer arm 22, which keeps the pad 62 in contact with the valve 24 in all modes of operation. When the system is in the linked or active mode, as illustrated in the drawings, the force F3 applied by the cam 20 to the roller 48 is transmitted from the contact element 38 of the inner arm, through the bolt member 28 to the external arm. 22, and valve 24, opening the valve against the force of the valve spring. The change of the system from an active to an inactive mode is performed when the roller 48 is in contact with the base circle portion of the cam and the forces acting on the bolt mechanism are at a minimum. In the idle mode, the bolt member 28 is removed from between the contact element 38 and the outer arm, allowing the inner and outer arms to pivot around each other in the whip adjuster, where the force F3 is insufficient to cause the movement of the valve. In this condition, the spring force F2 is calculated to keep the roller 48 of the inner arm in contact with the cam 20 and the outer arm in contact with the valve 24, while maintaining sufficient force against the plunger to counteract the force Fl of the plunger and prevent the whip adjuster from pumping. With reference to figure 7, the following equations define the previous forces, where "é." is defined as the fraction of the spring force that is applied to the stops 50 and 51, which prevents the whiplash adjuster from leaking ^ μ when the cam is in the base circle, and fixes the whiplash in the bolt member interface. (In theory, this force can be zero): (1) é = F5 / F2 (2) F2 = (Fl) (d) (c) / (cd) (a-éb) (3) F4 = (Fl) (d) / (cd) (4) F3 = (Fl) (c) / (cd) (5) F6 = (Fl) (c) [(d + a) + ér (db) / (cd) (a - £ b)]

Claims (12)

1. CLAIMS 1. A valve control system for an internal combustion engine that includes a cylinder head, a pipette valve, and a camshaft having a cam lobe formed therein; said control system comprising means in said cylinder head that define a pivot point; a first oscillating arm mounted for rotation about said pivot point and engageable with said pipette valve; a second oscillating arm mounted for rotation relative to said first oscillating arm and engageable with said cam lobe; means that polarize said first oscillating arm to be connected to said pivot point and said second oscillating arm to be connected to said cam lobe; and means for selectively interconnecting said first and second oscillating arms for unison movement about said pivot point in response to a force applied by said cam lobe to said second oscillating arm. ^^ 2. Apparatus as defined in claim 1, wherein said means for interconnecting said first and second oscillating arms comprise a plate member slidably mounted on one of said first and second oscillating arms and movable between a first position where it is connectable by the other of said oscillating arms and a second position where it is not connectable by said other oscillating arm, and operable means to move said plate member between said first and second positions. Apparatus as defined in claim 1, wherein said means biasing said first oscillating arm in connection with said pivot point and said second oscillating arm in connection with said cam lobe comprise a spring acting between said oscillating arms. first and second . 4. Apparatus as defined in claim 3, wherein said first oscillating arm comprises a first member Elongated arm # having a valve contact element formed at one of its ends, a first spring receiving surface formed at its opposite end, and a first pivot bearing element formed between said valve contact element and said spring receiving surface, said pivot bearing element defining a first concave bearing surface and a convex bearing surface; saying The second oscillating arm comprises a second elongated arm member having a contact surface formed at one of its ends, a second spring receiving surface formed at its opposite end, a second pivot bearing member formed between said contact surface and said spring receiving surface and having a second concave bearing surface formed therein, and a cam contact element between said pivot bearing member and said contact surface; said first arm member being received in said means defining a pivot point, the first concave bearing surface in contact with said pivot point, and said second arm member being received in said first arm member, the second surface of concave bearing being in engagement with said convex bearing surface; said spring acting between said first and second oscillating arms comprising a compression spring received between said first and second spring receiving surfaces. r, 5. Apparatus as defined in claim 4, in which said cam contact element comprises a roller mounted for rotation in said second arm member. Apparatus as defined in claim 4, wherein said first arm member comprises a generally rectangular structure having spaced side walls and converging end walls, one of said end walls defining said first spring receiving surface; and a raster element formed between said spaced walls, ^^ * - said first pivot bearing member being formed on said weft element; and said second arm comprises a generally rectangular structure including a generally U-shaped portion having spaced-apart walls and a closed end portion defining said contact surface, and a dorsal element formed between said walls, a first portion of said element dorsal defining said second pivot bearing element and a second portion of said dorsal element defining said second spring receiving surface; said first and second arms that interengage with said second arm being received within the spaced walls of the first spring retaining surfaces and said spring being arranged such that the biasing force of said spring is effective to maintain the second bearing surface of said spring. pivot in engagement with said first pivot bearing surface. 7. Apparatus as defined in claim 6, wherein said roller is mounted on a shaft received in transverse perforations formed in the spaced wall portions of said second arm, the shaft being retained by contact with the spaced walls. of said first arm. Apparatus as defined in claim 6, including one or more stops formed in said second arm and connectable with said first arm to limit relative movement between said first and second arms. 9. Apparatus as defined in claim 6, wherein the contact surface on said second arm is disposed in close proximity to the first convergent end portion of said first arm, said end portion having a flat surface formed therein. , and said plate member is slidable along said flat surface in a position where it is contacted by said contact surface when said arms are pivoted relative to each other. 10. Apparatus as defined in any of claims 1 to 9, wherein said pivot point is defined by the output member of a hydraulic whip adjuster mounted on said cylinder head. 11. A valve control system for an internal combustion engine that includes a cylinder head, a pipette valve and a camshaft having a cam lobe formed therein; said control system comprising a first oscillating arm pivotally mounted on said cylinder head Y engageable with said pipette valve; a second oscillating arm pivotally mounted on said cylinder head, said second oscillating arm having a roller mounted thereon engageable with said cam lobe; and means for selectively interconnecting said first and second oscillating arms for rotation in unison in response to a force applied by said cam lobe to said second oscillating arm; characterized in that said first oscillating arm is defined by spaced apart side walls, said second oscillating arm is received between said side walls, said roller is mounted on an axis received through said second oscillating arm, and said axis is retained axially by connection with said side walls . 12. A control valve system for an internal combustion engine, including a cylinder head, a pipette valve and a camshaft having a cam lobe formed therein; said control system comprising a first oscillating arm pivotally mounted on said cylinder head and connectable with said pipette valve; a second oscillating arm pivotally mounted relative to said first oscillating arm and engageable with said cam lobe; and means for selectively interconnecting said first and second oscillating arms for rotation in unison in response to a force applied by said cam lobe to said second oscillating arm, characterized in that said means for interconnecting said first and second oscillating arms comprise a moving plate member relative to said first and second oscillating arms between a first position where said plate member interferes with the relative rotation between said first and second oscillating arms and a second position allowing relative rotation between said oscillating arms first and second . F