BACKGROUND OF THE INVENTION
The present invention relates to electromechanical valve actuators and, more particularly, to compact electromechanical valve actuators.
As engine technology advances and manufacturers strive to increase engine power, improve fuel economy, decrease emissions, and provide more control over engines, manufacturers are developing electromechanical valve actuators (also known as electromagnetic valve actuators or EMVA) to replace camshafts for opening and closing engine valves. Electromechanical valve actuators allow selective opening and closing of the valves in response to various engine conditions.
Electromechanical valve actuators generally include two electromagnets formed from a lamination stack and an embedded power coil. A spring loaded lever armature located between the electromagnets is movable between the electromagnets as the power coils are selectively energized to create a magnetic force to attract the armature to the energized electromagnet. The surface of the electromagnets to which the armature is attracted when the power coil of an electromagnet is energized is generally referred to as a pole face. The armature is operationally coupled to the valve so that as the armature moves between pole faces in pole-face-to-pole-face operation, the valve is opened and closed.
One problem with traditional linear electromechanical valves is that each valve includes a relatively large set of electromagnets for opening and closing the valves, making it difficult to position all the electromechanical valve actuators on engines, especially on engines that have four or more valves per cylinder. Linear electromechanical valve actuators also generally draw a substantial amount of power from the alternator and with some engines having four or more valves per cylinder, the power drain on the alternator for the four or more electromechanical valve actuators is substantial. It is desirable to minimize power consumption of the electromechanical valve actuators in modern vehicles which have many competing power demands. In view of the drawbacks associated with linear electromechanical valve actuators, many manufacturers have recently been turning to lever electromechanical valve actuators, which due to their mechanical properties have substantial power savings. One problem with lever electromechanical valve actuators is still the package size required on the cylinder head. The package size is increased because the valve on lever electromechanical valve actuators is located well outside the envelope of the electromagnets, thereby increasing the package space required for each electromechanical valve actuator. An example of a prior art arrangement of lever electromechanical valve actuators 10′ over the cylinder 16 and location of the associated armature plate 32′ and valve 20 may be seen in FIG. 10. As shown in FIG. 10, electromechanical valve actuators on an engine having four valves 20 per cylinder 16 require significantly more space than camshafts, thereby presenting packaging concerns in engine compartments where space is limited. Therefore, there is a need for a compact lever electromechanical valve actuator with low power consumption.
SUMMARY OF THE INVENTION
The present invention relates to electromechanical valve actuators and, more particularly, to compact lever electromechanical valve actuators.
Compact electromechanical valve actuators allow the individual electromechanical valve actuators or pairs of electromechanical valve actuators to be situated in close proximity. The compact electromechanical valve actuator includes an armature plate having an armature envelope and a connecting rod pivotably coupled to the armature plate within the armature envelope. The electromechanical valve actuator further includes a spring assembly to which the armature plate applies a bi-directional force through the connecting rod to open and close the valve. The connecting rod is located at least partially within the envelope of the electromagnets and the envelope of the armature plate to reduce the amount of space required on the engine. The location of the connecting rod allows the lever electromechanical valve actuators to be located at least partially over the valve.
Further scope of applicability of the present invention will become apparent from the following detailed description, claims, and drawings. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the detailed description given here below, the appended claims, and the accompanying drawings in which:
FIG. 1 is a sectional view of the electromechanical valve actuator;
FIG. 2 is an enlarged sectional view of the armature plate;
FIG. 3 is a top sectional view;
FIG. 4 is a perspective view of the armature plate and connecting rod with the electromagnets shown in phantom lines;
FIG. 5 is a perspective view of an alternative armature plate and connecting rod with the electromagnets shown in phantom lines;
FIG. 6 is a top plan view of a second alternative armature plate showing the reinforcing pins with hidden lines;
FIG. 7 is a top plan view of the valve electromagnets for use in connection with the second alternative armature plate shown in FIG. 6;
FIG. 8 is an enlarged sectional view of the connecting rod coupled to the armature spring assembly with a wedge fastener;
FIG. 9 is an enlarged sectional view of an alternative embodiment with the connecting rod being coupled to the armature spring assembly with a pivot connection;
FIG. 10 is a prior art top plan view of the placement of lever electromechanical valve actuators on a cylinder head;
FIG. 11 is a top view of the armature plate of a second alternative embodiment;
FIG. 12 is a top view of the valve electromagnets of the second alternative embodiment;
FIG. 13 is a perspective view of the electromechanical valve actuator of the second alternative embodiment with the electromagnets shown in phantom lines;
FIG. 14 is a side sectional view of a third alternative embodiment; and
FIG. 15 is a top sectional view of the third alternative embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A lever electromechanical valve actuator 10, typically mounted on an internal combustion engine 12 to open and close a valve 20 (e.g., the intake or exhaust valves), is illustrated in FIG. 1. As described in greater detail below, the lever electromechanical valve actuator 10 of the present invention provides greater freedom in placement on the engine 12 a more compact arrangement, and allows the lever electromechanical valve actuator 10 to be situated at least partially over the valve 20. The electromechanical valve actuator 10 generally includes an armature assembly 30 having an armature plate 32, an electromagnet assembly 70 having electromagnets 72, 74, a connecting rod 90 and a spring assembly 60. The armature plate 32 is alternatively attracted to the electromagnets 72, 74, thereby applying a bi-directional force to the spring assembly 60 through the connecting rod 90 to open and close the valve 20.
The valve 20 is similar to traditional valves and generally includes a valve head 22 with a valve stem 24 extending therefrom. The valve 20 has an open and a closed position wherein in the closed position the valve head 22 seals a valve port 14 to the corresponding cylinder 16. The spring assembly 60 includes springs 62 and 64 sized to bias the armature plate 32 into an intermediate position, shown in FIG. 2, while the electromagnets 74, 74 are not energized.
The electromagnet assembly 70 controls the movement of the armature assembly 30, and thereby the movement of the valve 20. The electromagnets 72, 74 include cores 76 which may be formed from laminated plates (not shown) to improve the magnetic efficiency of the electromagnets 72, 74. A coil 78 is situated within each core 76 and is selectively energized to attract the armature plate 32 to the electromagnets 72, 74. C-blocks 8, 9 generally secure the electromagnets 72, 74 in position and are separated by a spacer block 6 to form the gap 15 between the electromagnets 72, 74 in which the armature plate 32 is located. The c-blocks 8, 9 may be formed without the need for a spacer, as shown in FIGS. 14 and 15. Also, the valve c-block 8, illustrated in FIG. 15, may support a bushing 43 to help reduce friction and increase longevity of the electromechanical valve actuator 10. The armature c-block 9 is typically a mirror image of the valve c-block 8, although other sizes, shapes, and configurations may be used. Of course, the spacer block 6 or a two part spacer block (not shown) may support a guide bushing to reduce friction. The c-blocks 8, 9 may be elongated and configured to hold a pair of electromechanical valve actuators 10 in line with each other (not shown). The c-blocks 8, 9 may also be formed as a double c-block, having an “E-configuration” (not shown) to hold a pair of adjacent electromechanical valve actuators 10. Of course, the c-blocks 8, 9 may also be configured to hold any number of electromechanical valve actuators 10, such as holding as many electromechanical valves actuators as there are valves 20 per cylinder 16. The c-blocks 8, 9 and spacer block 6 may be directly coupled to the engine 12 as illustrated in FIG. 1 or a housing (not shown) may secure them. In the illustrated embodiment, the housing generally fits over the electromechanical valve actuators 10 similar to a valve cover to protect the electromechanical valve actuators 10 from dirt and debris while retaining lubrication. The housing may cover individual electromechanical valve actuators 10, multiple electromechanical valve actuators 10, such as a pair or all electromechanical valve actuators over a particular cylinder 16 or all electromechanical valve actuators on a bank of cylinders. A base plate 17 may be installed on the engine 12 as shown in FIGS. 1 and 2.
The armature assembly 30 includes the armature plate 32 and the connecting rod 90. The armature plate 32 pivots about an armature pivot axis 44, near a pivot end 49 of the armature plate 32, to open and close the valve 20. The connecting rod 90 is coupled to the armature plate 32 near a lever end 48, opposite the armature pivot axis 44, and in a manner that transmits forces from the armature plate 32 to the connecting rod 90 in both the opening and closing directions. The armature plate 32 further includes a hinge pin 42 and at least one reinforcing pin 38. While the armature plate 32 may pivot relative to the hinge pin 42 it is generally desirable for the hinge pin 42 to be secured to the armature plate 32 so that the hinge pin 42 pivots with the plate 32 about the armature pivot axis 44 defined by center of the hinge pin 42 as illustrated in FIGS. 4, 5, and 15. The pivoting of the hinge pin 42 relative to the c-blocks 8, 9 and with the armature plate 32, as the armature plate 32 moves the valve 20 between the open and closed positions, has various benefits. First, the hinge pin 42 provides an economical and easy to assemble pivot without precise welding or machining of the armature plate to the hinge pin 42 or to a holder for the hinge pin 42. Second, the hinge rod aligns and secures the laminated plates 34 without precise machining of the armature plate and without welding the individual plates 34 together. Third, the hinge pin 42 may extend beyond the envelope of the armature plate 32 to allow attachment of a rotary position sensor 56, as illustrated in FIG. 3, for precise yet economical sensing of the rotational location of the armature plate 32. Fourth, by limiting the length of the hinge pin 42 upon which relative rotation occurs, friction losses from rotation can be minimized. Fifth, the hinge pin 42 also acts as a stiffening member to the armature plate 32. In the illustrated embodiment, the hinge pin 42 is secured to the armature plate 32 with an interference fit, but other techniques, such as coining the ends of the hinge pin 42 or welding the hinge pin 42 to the armature plate 32 may be used.
The armature plate 32 also includes a reinforcing pin 38 disposed laterally from the hinge pin 42. As illustrated in FIGS. 1-5, the reinforcing pin 38 may act as a pivot pin 40. More specifically, the connecting rod 90 may be pivotably coupled to the reinforcing pin 38 making that reinforcing pin 38 the pivot pin 40. The pivot pin 40 stiffens the armature plate 32 to prevent flex of the armature plate 32 as well as distributes forces from the connecting rod 90 longitudinally across the laminated plates 34. More specifically, the reinforcing pin 38 prevents shearing of the laminated plates 34 as the armature plate 32 applies force to the connecting rod 90. Use of a pivot pin 40 that also acts as a reinforcing pin 38 helps improve magnetic efficiency of the armature plate 32 by minimizing potential disruptors to the magnetic flux through the armature plate 32 near the lever end 48. The lever end 48 has the highest magnetic attraction and becomes saturated with magnetic flux, under some conditions. In the illustrated embodiment, the reinforcing pin 38 is secured to the armature plate 32 with an interference fit by being forcibly inserted into aligned holes in the laminated plates 34, but may be secured to the armature plate 32 by any known method, including coining the ends of the reinforcing pin 38 or welding the reinforcing pin 38 in place. A stiffer armature plate 32 minimizes flexing as the armature plate pivots and thereby provides more efficient operation. The additional stiffening of the armature plate 32 also allows placement of the connecting rod 90 anywhere along the lever end 48 of the armature plate 32, as illustrated in FIGS. 4 and 5.
To further improve magnetic efficiency and package size, the longitudinal extent 52 of the armature plate 32 may be 1.2 times greater than the lateral extent 50 of the armature plate 32, as illustrated in FIG. 11. The armature plate 32 may also include a protruding portion 54 (FIG. 6) designed to improve the mechanical advantages of the lever electromechanical valve actuator 10. The electromagnets 72, 74 may also include a protruding portion 55, as illustrated on the valve electromagnets 74 in FIG. 7. To further improve magnetic efficiency, packaging and durability, as well as minimize the moving mass of the armature plate 32, the armature plate 32 may be formed with surfaces that are not parallel, as illustrated in FIG. 14. In FIG. 14, the armature plate 32 tapers from the pivot end 49 to the lever end 48.
To provide a more compact electromechanical valve actuator 10, the armature plate 32 includes a recess 36. The recess 36 receives the connecting rod 90 so that at least a portion of the connecting rod 90 is located within the envelope of the armature plate 32. As used throughout the specification and in the claims, the term “envelope of the armature plate” or “armature plate envelope” generally refers to the outer perimeter of the armature plate 32 without any recesses, such as the illustrated recess 36. Therefore, any point within the outer perimeter of the armature plate 32 irrespective of the recess 36 is located within the envelope of the armature plate 32 The envelope of the armature plate 32 generally does not include any welded protrusions that do not function to magnetically attract the armature plate 32 to the electromagnets 72, 74. The recess 36 is designed to provide the space necessary for the connecting rod 90 to pivot freely about pivot pin 40. A compact electromechanical valve actuator 10 facilitates packaging flexibility, such as allowing the electromechanical valve actuators 10 to be placed in close proximity to one another on the engine 12. As shown in FIGS. 11-14, the recess 36 may be located anywhere within the envelope of the armature so long as the connecting rod 90 may drive the valve 20 without interfering with the power coils 78. By locating the connecting rod 90 at least partially within the envelope of the armature plate, the electromechanical valve actuator 10 may be located at least partially over the valve 20 as illustrated in FIG. 3. Even when the connecting rod 90 is pivotably coupled to the armature plate 32 closer to the lateral center, as illustrated in FIG. 13, the recess 36 may still extend from the lever end 48 to beyond the pivot pin 40. The recess 36 extending to the lever end 48 facilitates manufacturing and shipping of the armature assembly 30 by allowing the connecting rod 90, specifically the shaft 96 to be rotated and to be generally aligned with the armature plate 32 for shipping. Aligning the connecting rod 90 with the armature plate 32 during shipping shrinks the size required for each armature assembly 30, and minimizes potential damage to the armature assembly during shipment.
The connecting rod 90 may be made in almost any size and shape so long as it transfers bi-directional force from the armature assembly 30 to the spring assembly 60. The connecting rod 90 is illustrated in FIGS. 1 and 8 as having a pivot pin passage on an armature end 92 and a wedge 100 secured to the valve end 94 with a shaft 96 therebetween. The wedge 100 is similar to wedges used in valve spring retainers for camshafts for ease of manufacture and low cost. The connecting rod 90 pivots about the pivot pin 40 and the design of the spring assembly 60 including the wedge 100 allows some pivoting relative to the valve stem 24 during the arcuate movement of the lever end 48 of the armature plate 32. In FIG. 8, the connecting rod 90 extends toward the valve 20 and during opening of the valve 20, the connecting rod 90 is axially displaced to contact the valve stem 24. The wedge 100 is mechanically trapped between the connecting rod 90 and the armature spring retainer 68 by the force applied by the armature spring 64. More specifically, the wedge 100 includes two keepers which are assembled into a groove (not shown) on the connecting rod 90 and the force applied by the armature spring 64 to the armature spring retainer 68 keeps the wedge 100 secured within the groove on the connecting rod 90, so that the connecting rod 90 may apply bi-directional force to the spring assembly 60. Alternatively, the wedge 100 may be press fit, welded, or otherwise secured on the connecting rod 90. The slightly rounded ends of the valve stem 24 and connecting rod 90 allow a limited range of pivotal movement relative to each other as the armature plate 32 pivots. The valve spring 62 is also retained by a valve spring retainer 66.
The connecting rod 90 may include other variations where the connecting rod extends toward the valve stem 24 and pushes directly on the armature spring retainer 68, valve spring retainer 66, or valve stem 24 to provide bi-directional force to the spring assembly 60 without using the wedge. In an alternative embodiment, shown in FIG. 9, the connecting rod 90 may be coupled to the armature spring retainer 68 with a retainer pin 69 in place of the wedge 100 allowing the connecting rod 90 to freely pivot at both ends 92 and 94.
The spring assembly 60 is located between the electromagnet assembly 70 and the cylinder 16 as illustrated in FIG. 1. The spring assembly 60 includes the valve spring 62 and the armature spring 64, each of which are, as illustrated, preferably located below the armature plate 32 for a more compact valve actuator 10. The valve spring 62 provides the closing force to the valve 20 and is retained on the valve stem 24 by a valve spring retainer 66. The armature spring 64 assists the armature assembly 30 in opening of the valve 20 by providing an opening force. The armature spring 64 is retained on the connecting rod 90 by an armature spring retainer 68. The placement of the springs 62 and 64 below the armature plate 32 provides opposed spring forces to facilitate the desired movement of the armature plate 32 while improving the overall compactness of the actuator relative to prior art designs. The combination of the opposing springs 62, 64 located below the armature plate 32 also prevents the opposing spring forces from being carried by the connecting rod 90, any bushings coupled to the connecting rod to facilitate pivoting, and the armature plate 32.
The valve electromagnet 72 may include a valve electromagnet recess 82 as illustrated in FIGS. 1-5, 7, 11, 13, and 14, and the armature electromagnet 74 may include a pivot recess 84 as illustrated in FIG. 1. The valve electromagnet recess 82 and the pivot recess 84 are in alignment with the recess 36 in the armature plate 32 to receive the connecting rod 90 at least partially within the envelope of the electromagnets 72, 74. As used throughout the specification and in the claims the terms “envelope of the armature magnet,” “envelope of the valve electromagnet,” or “envelope of the electromagnets” generally refers to the outer perimeter of the electromagnet 72, 74 without the recesses 82 and 84. With the connecting rod 90 movable at least partially within the envelope of the electromagnets 72, 74, the electromechanical valve actuators 10 may be located in closer proximity to each other and arranged on the engine 12 in a more compact fashion. As illustrated in FIG. 1, the valve 20 may be located at least partially under the electromagnets 72, 74.
As illustrated in FIGS. 14 and 15, the hinge pin 42 may be substantially larger than the reinforcing pins 38, to carry the applied load as the valve 20 is cycled between the open and closed positions. The hinge pin 42 may rotate in bushings 43 to reduce friction. Although not illustrated, the connecting rod 90 may also be pivotably coupled to the pivot pin 40 with bushings to reduce friction. As further illustrated in FIG. 15, the location of the reinforcing pins 38 may vary if any reinforcing pins 38 are included that are not pivot pins 40.
The compact electromechanical valve actuators 10 described above provide space savings and facilitate the use of more compact actuator placement patterns relative to each cylinder. The connecting rod 90 being coupled at both ends 92, 94 also allows the elimination of guide bushings typically used to traditionally guide an armature stem. Elimination of the guide bushing reduces friction and assembly cost. Reduction in friction is desirable because it allows operation of the electromechanical valve actuator 10 with less power consumption.
The present invention provides a lever electromechanical valve actuator 10 with compact packaging over the engine. Compact packaging is provided for by using a connecting rod 90 that is at least partially located within the envelope of the electromagnets 72, 74 and armature plate 32. The compact packaging is further facilitated by locating the spring assembly 60 between the electromechanical valve actuator 10 and the cylinder 16. The armature plate 32 provides a bi-directional force through the connecting rod 90 to move the valve between an open and closed position. The compact actuator design allows the valve 20 to substantially be located under the armature plate 32 or valve electromagnet 72 as shown in FIG. 3.
The foregoing discussion discloses and describes an exemplary embodiment of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the true spirit and fair scope of the invention as defined by the following claims.
Patent Application
20050076866
