Quick switching armature with centering spring

Abstract

A moving actuator is described that operates between two extreme positions defined by mechanical stops. The actuator includes an armature block movable relative to an armature body, a rigid armature spring arranged so that the natural rest position of the armature block is near the center of travel between the two extreme positions, and a pair of latches having sufficient holding force so that the armature block can be held in either extreme position against the restoring force of the spring, and which can be quickly released relative to the natural period of oscillation determined by the armature block on the armature spring.

Description

Technical Field

[0001] In its most general form, the invention has potential applications in almost every field currently in use or where solenoids can be used. Applications of interest require rapid and reversible movement of the armature between two discrete positions.

[0002] The invention was originally aroused by controlled actuation of a lift valve for use in internal combustion engines, reciprocating gas compressors, reciprocating gas expanders and other machines, wherein the lift valve is used to open and close a communication channel between any two gas chambers (typically a "cylinder" and a "manifold").

[0003] This invention is particularly applicable to lift valves operating in a manner where the pressure difference between the two gas chambers does not generate a significant force that would cause the lift valve to open. In machines designed as reversible reciprocating compressors or expanders, the lift valve located between the low-pressure manifold and the cylinder will open inward, as is the case with lift valves found in almost all modern internal combustion engines; however, the lift valve located between the high-pressure manifold and the cylinder will open outward, because the cylinder pressure typically hovers between the pressures in the manifold. Background Technology

[0004] For clarity, the background of this invention is presented in the context of lift valve actuation, although the concept itself has a broader applicability.

[0005] Many reciprocating machines use lift valves to determine when there is and when there is no continuous communication between two gas chambers. The most familiar example is the internal combustion (IC) engine. The same lift valve device is common for both diesel and gasoline engines.

[0006] In the original design of the engine, and indeed in most modern IC engines, the lift valve opens via a cam that rotates with the camshaft and returns to its closed position via a spring. These arrangements have two major drawbacks: (1) the level of power loss associated with valve actuation is quite high, and (2) it is very difficult to change the valve opening and closing angles in a controlled manner.

[0007] The high loss levels in these conventional designs arise because the cam exerts a considerable force on the valve while simultaneously opening it (doing a significant amount of work). The return spring then pushes the valve back to the closed position. High contact forces typically exist between the valve top and the cam in both the opening and closing directions, and these contact forces have associated friction, which in turn contributes to losses.

[0008] Significant effort has been invested in increasing the flexibility of camshaft-driven valve actuation in integrated circuit (IC) engines by adding mechanisms to the camshaft or its drivers to alter timing, lift, and dwell. However, the mechanisms that enable these variations greatly increase the complexity of the camshaft system. Examples include hydraulic and electromechanical actuators for adjusting the camshaft phase relative to the crankshaft, variable eccentric drives for increasing or decreasing the time spent at the high point of the cam lobe angle, and switchers between multiple cam profiles on a single shaft. Despite the cost and complexity of these solutions, they cannot achieve fully variable operation, thus failing to provide continuous variation within a limited range or multiple discrete operational configurations.

[0009] The present invention aims to at least partially improve some of the problems mentioned above. Summary of the Invention

[0010] According to one aspect of the invention, a moving actuator is provided that operates between two extreme positions defined by a mechanical stop, the moving actuator comprising: an armature block movable relative to an armature body; a rigid armature spring configured such that the natural rest position of the armature block is close to a center of travel between the two extreme positions; and a pair of latches having sufficient holding force to hold the armature block in either extreme position against the restoring force of the spring and to be rapidly released relative to the inherent period of vibration determined by the armature block on the armature spring.

[0011] In one embodiment, the latch can be magnetically implemented, held in place by a magnetic flux driven by a permanent magnet material and released very quickly by a current pulse that generates a magnetomotive force pattern opposite to that provided by the permanent magnet material.

[0012] In a second aspect, an actuation system for a lift valve based on the movable actuator of the first aspect is provided, wherein the lift valve is an integral part of the armature block, and wherein the pressure difference maintained by the lift valve in its closed position is primarily or exclusively used to hold the armature block in that position against the restoring force of the spring.

[0013] By providing an acoustic chamber within the valve body housing, the actuation system can be customized to operate at a specific frequency, ensuring that the dynamic gas pressure within the actuation system does not significantly impede the movement of the armature block.

[0014] Typically, independently actuated valves can offer the potential for better engine performance at locations far from a single operating design point, and they also eliminate the power loss associated with friction between the cam and the top of the valve.

[0015] There are many arrangements for actively actuated valves. Most are electrohydraulic, where a local hydraulic actuator directly attached to the valve is powered by a remote hydraulic power source. Some utilize direct electric (electromagnetic) actuation, but the disadvantage of these arrangements is that the actuator requires a relatively large size. This large size is also advantageous because the instantaneous force required to accelerate the valve is very large.

[0016] For maximum efficiency, the valve should open and close relatively quickly. In ideal valve operation, the valve opens when the pressure difference between the two discrete gas chambers is (close to) zero, and closes when the volumetric flow rate between the two chambers is (close to) zero. Depending on the engine's operating conditions, these ideal opening and closing moments can occur at different angles of the crankshaft.

[0017] In an embodiment, the present invention provides a method for actuating a lift valve, comprising:

[0018] • All power can be drawn from direct electric actuation without involving hydraulic devices;

[0019] • Allows for precise control of the valve's opening and closing times;

[0020] • Provides very fast valve opening and closing;

[0021] • Avoid any strong impact at the end of the valve movement.

[0022] In broader terms, the present invention can provide an actuation method for rapidly switching armatures, comprising:

[0023] • All power can be drawn from direct electric actuation without involving hydraulic devices;

[0024] • Allows for precise control over the timing of switching shipments;

[0025] • Offers very fast switching between delivery services;

[0026] • Avoid any strong impact at the end of armature movement.

[0027] First, let me explain the basic principles of this invention.

[0028] A lift valve can be represented as a single discrete block in a dynamic system. We call this the valve block m.

[0029] The valve block typically has mechanical stops at both ends of its stroke, spaced 2h apart. The stops are located at approximately +h and -h.

[0030] Each mechanical stop typically has a "latch mechanism" that can engage the valve block when it reaches its limit position and release it from rest at any time from that limit position.

[0031] The valve block can be connected to the ground via a valve spring with stiffness k. Note that a portion of the valve spring moves with the valve block, while another portion remains grounded. Therefore, the valve spring itself contributes to the valve block itself, but this contribution is significantly less than the total mass of the valve spring as a single object. In some embodiments, the valve spring can be implemented as multiple separate springs operating in parallel.

[0032] Each latching mechanism must typically have sufficient authority to prevent the valve block from being pulled away from its limit when the valve spring provides its maximum force—attempting to pull the valve block towards the center of its stroke.

[0033] The system can operate in four discrete modes, which typically occur in a cyclical order:

[0034] • The valve block is locked at the low position;

[0035] The valve block is being transported upwards;

[0036] • The valve block is locked at a high position;

[0037] The valve block is being transported during its descent.

[0038] During the period when the valve block is locked at a low position or a high position, the valve actuation system remains completely still and nothing happens. A highly desirable characteristic of a latching system is that it should not consume power to maintain the latching force. Some details of possible magnetic latching systems are discussed in later sections, where a permanent magnet provides the magnetic flux to hold the valve block in place.

[0039] During the movement of the valve block, the valve block-spring assembly can function like a single-degree-of-freedom (SDoF) system, which has been released from a position a distance h from the equilibrium position. If no latch engages after release, the SDoF system will operate at an initial amplitude and natural frequency of h. Oscillations. In reality, due to parasitic losses in the SDoF system, the oscillations will gradually disappear, and the valve block will eventually stabilize at its equilibrium position.

[0040] Intentionally making the resonant frequency f n The chosen frequency is much higher than the engine's maximum RPM. The valve delivery time is almost precisely 1 / (2f) n Furthermore, the displacement curve of the valve block is very similar to a single half-cycle of a cosine wave.

[0041] Typically, except at the start of transport when a latch is released, the discharge latch can actively push the valve block away, and at the end of transport, the receiving latch will usually be pulled out of the valve. No significant excitation is applied to the resonant block during valve rise or valve fall transport.

[0042] Ignoring parasitic losses, the net energy consumed in any single transport is approximately zero. Specifically, there is no impact. Impacts, of course, do cause an immediate loss of kinetic energy, so avoiding impacts helps conserve energy.

[0043] A simple example can be used to illustrate the design process of this valve actuation system. Assume the valve block itself (including contributions from the valve spring) comprises m = 200g (0.2kg), and we want the valve to achieve a total range of motion of 9mm, i.e., h = 4.5 × 10⁻⁶. -3 (m). Assume the required delivery time is approximately 2.5 ms. Then the natural frequency is calculated as f. n =200Hz, and then the stiffness of the valve spring is calculated as k=0.2×(2π×200) 2 =315.8 kN / m. The force existing in the valve spring at any limit of the strain is 1.421 kN. The peak strain energy in the valve spring is 3.198 J, which is the same as the peak kinetic energy of the valve block when it passes through the intermediate stroke point. At any such moment, the velocity of the valve block is 5.65 m / s.

[0044] We will now describe some features of the present invention.

[0045] An actuation system for a lift valve is designed to facilitate rapid switching of the valve between two discrete positions (typically corresponding to fully open and fully closed).

[0046] Within this system, the lift valve itself acts as a discrete block (valve block) grounded via a valve spring (the body of the machine containing the valve seat). When there is no external force on the valve and if the valve does not experience acceleration, the valve spring will tend to position the valve block close to the center of its stroke.

[0047] The travel of a lift valve between its two discrete positions is limited by a mechanical stop. In one direction, this mechanical stop is typically the lift head itself, which contacts the valve seat.

[0048] At each limit of the valve block's stroke, a latching device may be present, which is able to hold the valve at that limit of its stroke even in the presence of a force attempting to move the valve back toward the center of the stroke.

[0049] Latching devices are typically able to release latching force over a short period of time, even relative to the valve transport time. They are also able to provide net positive work to the valve block during any single valve transport, in the sense that the work done on the valve block by the receiving latch as the valve block approaches the end of its transport is greater than the work done by the valve block on the discharge latch at the beginning of transport.

[0050] The latching device can be implemented in the form of a fast-release magnetic latch, wherein permanent magnets incorporated into the magnetic circuit provide the magnetic flux that keeps the latch closed, and wherein the magnetic flux flux (MMF) present in those permanent magnets is offset relative to the MMF by a coil present in the magnetic latch. The magnetic circuit in this fast-release magnetic latch will be formed of a ferromagnetic / ferrimagnetic material with high resistivity, or it will be formed with an internal geometry that naturally disrupts the continuity of the electrical path, so that eddy currents do not significantly impede the rapid changes in magnetic flux required for the fast-release latch.

[0051] While valve springs can sometimes be implemented using one or more helical springs, a key feature of this invention is that the valve spring must be double-acting, because during any single valve stroke, the force in the valve spring changes from entirely upward to entirely downward, and vice versa. Another important feature of this invention is minimizing the total mass causing travel, which helps reduce the time spent on complete valve transport or the force capacity required in the latch (or both). With this in mind, there is a strong sensitivity regarding the mass of the valve spring that effectively travels with the valve block. Therefore, the valve spring can be implemented as one or more planar springs that collectively serve as valve stem guides to hold the valve stem on its intended centerline.

[0052] The motion is an example of rotation rather than translation.

[0053] In many applications, it is required that the armature rotate between two discrete positions rather than translate between them. The exact same principle applies to two different cases. Conceptually, the only difference is:

[0054] • The armature block (valve block) is replaced by an armature inertial component;

[0055] • Armature springs (valve springs) are torsion springs in rotating housings;

[0056] • The upper and lower latches become latches at the two angular limits of the movement (mostly clockwise and mostly counterclockwise).

[0057] Extended implementation examples.

[0058] A key problem with this invention is that the valve block should not be in a balanced state at the center of its stroke. The core intention is that once the valve block has been released from the discharge latch, it should have passed that balanced position and almost reached the opposite end of its stroke, where the receiving latch should pull it into a new locked position. However, some strategies are necessary to accommodate the chance possibility that the valve block may end at its balanced position at the center of its stroke.

[0059] When the valve block is near its center of travel, the magnetic latches may have a relatively small effect on the valve block. One possibility for restoring this situation is to oscillate the "activation" of the two latches in sequence at frequencies close to the resonant frequency of the valve block, allowing the vibrations of the valve block to accumulate, and eventually these oscillations to become large enough to move the valve block to a latch position.

[0060] The second possibility is that the valve block can be equipped with some independent actuation sources. This independent actuation can take the form of piezoelectric strips adhered to the opposite surfaces of the components of the planar spring.

[0061] A third possibility that can be used in combination with the two methods mentioned above is to install a device that allows air (or process gas) to flow at a high rate through the half-open valve to amplify the oscillation of the valve block until the valve block can be locked at a point where the stroke is at a limit.

[0062] A particular consideration of this invention is recoil. The valve actuation system proposed herein applies a very significant force to the body of the engine or machine for a very short period of time, followed by an opposing force profile. If the body of the engine or machine is relatively light or relatively flexible, two possible drawbacks exist. These drawbacks are: (a) some significant noise may be generated, and (b) some of the energy used to move the valve through its predetermined stroke will leak into the machine body. The solution to this problem is to use a symmetrical system in which two distinct blocks with very similar moving mass values ​​are actuated in opposite directions. This provides the possibility of recoil-free operation.

[0063] This invention teaches a solution for very common situations where the main body (armature) needs to rapidly alternate between two positions within a controllable time, with a dwell period at each of the two positions. A concrete example is a valve such as a lift valve, where optimal performance of the main body requires the time required for the lift valve to change from fully open to fully closed and from fully closed to fully open to be very short relative to the total cycle time of the piston in the cylinder. Applications also include rotary valves, electrical switches, flow control guides in production lines, switch rail assemblies on railway tracks, and other environments. Springs attached to the armature and tending to center the armature in the middle (or near the middle) of its stroke clearly have the potential to achieve the desired task. This invention teaches that a system comprising an armature block (or inertial element), a centering spring, and a latching device at the end of the valve stroke can achieve highly efficient controllable and rapid actuation. Here, all energy input comes from electrostatic or electromagnetic actuation, without resorting to hydraulic devices, and there is no strong impact at the end of the armature movement.

[0064] These and other aspects of the invention will become apparent and will be explained with reference to the embodiments described below. Attached Figure Description

[0065] Embodiments will be described by way of example only with reference to the accompanying drawings, in which:

[0066] Figure 1 The invention is illustrated in schematic form;

[0067] Figure 2 A first embodiment of the present invention is shown;

[0068] Figures 3 to 6 Some details of a possible construction of a magnetic latch for the latching function required by the present invention are provided;

[0069] Figure 7 The outline of a single plane of spring steel is shown, which can serve the combined function of guiding the valve stem and providing a spring force that tends to drive the valve stem back toward the center of the stroke.

[0070] It should be noted that the accompanying drawings are schematic and not drawn to scale. For clarity and convenience, the relative dimensions and scales of the components in these drawings are exaggerated or reduced in size. The same reference numerals are generally used to indicate corresponding or similar features in modified and different embodiments. Detailed Implementation

[0071] Typical implementation.

[0072] Figure 1The invention is illustrated in schematic form and reveals four key components required to realize the invention: valve block 1, valve spring 2, lower latch 3 for holding the valve block at the lower end of its stroke, and upper latch 4 for holding the valve block at the upper end of its stroke.

[0073] To improve clarity throughout the description of this invention, we focus on applications involving valve actuation, while recognizing that a wider range of applications are also possible. In more general applications, valve block 1 will simply be an armature block, and valve spring will be an armature spring.

[0074] The lower and upper latches must each be able to release the valve block extremely quickly, and each latch must be able to do more work for the latch than is done during the release event when the valve block is pulled away to attract the valve block toward it. The difference between these two amounts of work must be sufficient to compensate for the small parasitic losses that inevitably occur during the valve transport event.

[0075] First embodiment.

[0076] Figure 2 It shows the following Figure 1 The diagram illustrates a possible embodiment of the invention. In this embodiment, components 11, 12, 13, 14, and 15 are all elements of valve block 1. Accordingly, components 21, 22, 23, and 24 are all combined to form valve spring 2. The lower latch 3 is... Figure 2 It is shown as a single object, but Figure 3-5 Further insights into this are provided. Similarly, the upper latch 4 in Figure 2 It is shown as a single object, and its properties may be similar to or the same as those of the lower latch. Figure 2 In the case, the components of the housing are numbered from 51 to 59.

[0077] The valve block includes: the lifting head itself 11, the valve stem 12, the first valve stem-spring coupling 13, the second valve stem-spring coupling 14, and the target disk 15, which comprises a ferromagnetic material and is configured (using a high-resistance material or other electrically discontinuous material) to allow very rapid changes in the flux through its axial surface.

[0078] The valve spring in this embodiment comprises four parallel planar springs, which are formed from spring steel sheets 21, 22, 23 and 24, as described later.

[0079] The main body of the valve actuation system includes a valve seat 51, a bushing 52 for maintaining alignment between the valve stem and the valve seat, a retaining plate 53 for the bushing, a first main valve body 54, a second main valve body 55 for securing two planar springs 23 and 24, a third main valve body 56 for carrying the lower latch 3, a fourth main valve body 57 for carrying the upper latch 4, a fifth main valve body 58 for securing the remaining two planar springs 21 and 24, and finally a top part 59 of the valve body that ultimately seals the valve chamber.

[0080] Figure 3-6 Each lower latch is shown to be implemented as a set of eight individual ferromagnetic (or subferromagnetic) pole pieces 301-308 and eight corresponding permanent magnet material pieces 311-318. Typically, such a universally constructed magnetic latch can be implemented with any even number of pole pieces, but eight is a convenient number for illustration. Note that in this context, the terms "ferromagnetic" and "subferromagnetic" are used to refer to materials that have high permeability to magnetic flux over a good flux density range (typically up to ~2 Tesla) and do not have a wide hysteresis loop. The term "soft magnetic material" may be used by some to refer to such materials.

[0081] Corresponding to each individual permanent magnet component, coils 321-328 are provided. When a coil is excited by current in one direction, the MMF generated by that coil is opposite to the MMF generated by the magnet. In this way, the magnetic latch can be released very quickly. All coils are connected together such that the MMF contributions of all permanent magnets are simultaneously opposite.

[0082] Figure 3 A plan view of the lower latch is shown, and the magnetization directions of permanent magnets 311-318 can be clearly seen from the arrows presented in the image. In this figure, each pole has a circumferential surface in contact with two different permanent magnet components, and these permanent magnet components are magnetized in opposite circumferential directions. That is, if a permanent magnet component on one side of a pole attempts to drive flux in a clockwise direction (viewed from above), then a permanent magnet component on the opposite side of that pole attempts to drive flux in a counterclockwise direction (viewed from above).

[0083] Figure 4 An oblique view of a single pole piece is shown. Figure 5 A second plan view of the lower latch is shown, in which the axial surface is shown more clearly. Coils 321-328 are omitted in this view. Figure 6 An oblique view of the assembled latch is shown, again omitting the included coils 321-328.

[0084] Figure 7A view of one of the possible geometries of a plane spring 21-24 is shown. Here, the plane spring is formed by stamping, laser cutting, or water-jet morphology from a flat sheet blank. The "spokes" that connect the outer ring to the inner ring are intentionally much wider near the outer ring than near the inner ring, because the intention is that when the plane spring deflects to its maximum extent, the slope of each "spoke" is close to zero at the outer ring, but is firm at the inner ring. In this way, the strain energy is concentrated in the spring material without much movement, and the primary function of the spoke material near the inner ring is to transmit force.

[0085] Other variations and modifications will be apparent to those skilled in the art upon reading this disclosure. Such variations and modifications may involve equivalents and other features known in the art, and may be used in place of or in addition to the features already described herein.

[0086] Although the appended claims relate to specific combinations of features, it should be understood that the scope of the disclosure of this invention also includes any novel feature or any novel combination of features or any generalization thereof explicitly or implicitly disclosed herein, whether or not it relates to the same invention as currently claimed in any of the claims, and whether or not it alleviates any or all of the same technical problems as those of this invention.

[0087] Features described in the context of a single embodiment may also be provided in combination in a single embodiment. Conversely, for the sake of brevity, the various features described in the context of a single embodiment may also be provided individually or in any suitable sub-combination. The applicant hereby informs that new claims may be formulated during the examination of these features and / or combinations of these features.

[0088] For completeness, it is also stated that the term "comprising" does not exclude other elements or steps, the term "a" or "an" does not exclude multiple, and the reference numerals in the claims should not be construed as limiting the scope of the claims.

Claims

1. A moving actuator that acts between two extreme positions defined by a mechanical stop, comprising: An armature block that can move relative to the armature body; A rigid armature spring is provided, which is configured such that the natural rest position of the armature block is close to the center of travel between the two extreme positions; as well as A pair of latches, the latches being magnetically implemented, held in place by a magnetic flux driven by a permanent magnet material and released by a current pulse generating a magnetomotive force mode opposite to that provided by the permanent magnet material, and the latches having sufficient holding force to allow the armature block to remain in either extreme position against the restoring force of a rigid armature spring, and being able to be released within a period shorter than the inherent period of the block-spring combination oscillation determined by the armature block connected to the rigid armature spring; wherein the outline of each of the pair of latches includes: The first platform section extends outward from the central axis of the movable actuator; The ramp portion extends from the first platform portion; and The second platform portion extends from the ramp portion, wherein the thickness of the pair of latches is greater in the length direction of the first platform portion than in the length direction of the second platform portion.

2. The movable actuator according to claim 1, wherein, The pair of latches are made of a material with high resistivity.

3. An actuation system for a lift valve based on the movable actuator of claim 1, wherein, The lift valve is an integral part of the armature block, and the pressure difference maintained by the lift valve in its closed position is primarily or specifically used to hold the armature block in that position against the restoring force of the rigid armature spring.

4. A movable actuator acting between mechanical stops, the movable actuator comprising: A valve block that can move between the stops; A valve spring acts on the valve block, and the valve spring has a stationary position between the stops; A lower magnetic latch is used to magnetically hold the valve block at the lower end of its stroke by a magnetic flux driven by a permanent magnet material in the lower magnetic latch. as well as An upper magnetic latch is used to magnetically hold the valve block at the upper end of the stroke by a magnetic flux driven by a permanent magnet material in the upper magnetic latch; as well as Each latch includes a ferromagnetic material, a permanent magnet material, and a coil configured to be energized by a current to provide a magnetomotive force, wherein the magnetomotive force of the permanent magnet material cancels out the magnetic force of the latch, such that the latch is configured to release the valve block in a period shorter than the inherent period of the oscillation of the block-spring combination determined by the valve block connected to the valve spring, wherein each of the lower magnetic latch and the upper magnetic latch includes: The first platform section extends outward from the central axis of the movable actuator; The ramp portion extends from the first platform portion; and The second platform portion extends from the ramp portion, wherein the thickness of each of the lower magnetic latch and the upper magnetic latch is greater in the length direction of the first platform portion than in the length direction of the second platform portion.

5. The movable actuator as claimed in claim 4, wherein, The valve block includes a lifting head, a valve stem, a valve stem-spring interface joint, and a target disk, the target disk being made of ferromagnetic material and configured to allow rapid changes in flux through the axial surface of the target disk.

6. The movable actuator as claimed in claim 5, wherein, The valve spring comprises four parallel planar springs.

7. The movable actuator as claimed in claim 6, wherein, The planar spring comprises spring steel sheets.

8. The movable actuator as claimed in claim 6, characterized in that, It also includes a valve body, in which the valve block is movable relative to the valve body.

9. The movable actuator as claimed in claim 8, wherein, The valve body includes a valve seat and a bushing for maintaining alignment of the valve stem with the valve seat.

10. The movable actuator as claimed in claim 9, wherein, The valve body also includes retaining plates for the bushing and body components, each body component being used to secure the planar spring or the latch.

11. The movable actuator as claimed in claim 4, wherein, The lower magnetic latch includes multiple pole pieces and corresponding permanent magnet material pieces.

12. The movable actuator of claim 11, wherein, The permanent magnet component is aligned with the excitation coil used to operate the latch.

13. The movable actuator according to claim 4, wherein, The ferromagnetic materials of the lower magnetic latch and the upper magnetic latch contain materials with high resistivity.

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