Patent Application
20180216986
This invention relates to damping mechanisms for electronics, and more particularly to integrally formed damping areas on a circuit board, such as a printed circuit board (PCB), used in harsh environments where electronics connected to the PCB may be subjected to vibration or acceleration forces transmitted from motorized vehicles, stationary devices, industrial equipment, and so on.
PCB's and the like, including electronic components connected thereto, are found in many devices that may be intermittently or constantly exposed to shock, vibration, or other forces based on acceleration and/or deceleration, centrifugal forces, and so on, that may exceed the design limits of the PCB's and/or the components connected thereto. For example, a relatively small hand-held device, such as a smartphone or the like, may be dropped onto a hard surface and thus be subjected to acceleration forces as the instrument falls, and abrupt deceleration forces upon impact of the device with the surface. Such a scenario may also create additional oscillations as the device continues to bounce along the surface in most likely random orientations, thereby introducing corresponding centrifugal forces. One or more of the resultant forces may cause propagating cracks in the PCB which may interfere with conductive traces associated therewith, as well as electronic component failure, breakage, and/or separation from the PCB. Likewise, relatively large vibrational forces created by stationary equipment and vehicles used for transportation, construction, farming, aviation, and marine industries can have negative effects on PCB's and related electronic components when resultant forces exceed the strength of PCB and electronic component materials as well as the adhesion strength between such materials.
Some electronic components associated with the above-mentioned industries can be relatively fragile in nature, and therefore great care must be used when designing equipment employing such components. For example, transducers for measuring liquid level are often used in vehicles, industrial equipment, as well as other mobile and stationary systems. The electrical output of such transducers varies in response to a change in the liquid level being measured and is typically in the form of a change in resistance, capacitance, current flow, magnetic field, and so on. These types of transducers may include PCB's or other platforms with variable capacitors or resistors, optical components, Hall-effect sensors, reed switch arrays, and so on.
For liquid level transducers employing reed switches, a plurality of reed switches are usually arranged in series with a plurality of resistors along the length of a PCB. The reed switches are normally responsive to the presence and absence of a magnetic field for opening and/or closing the switch. A float rides along the surface of the liquid to be measured and is constrained to move in a linear direction along the PCB. The float usually includes an embedded magnet to trip one of the reed switches as the float moves in response to a change in liquid level in the tank. Thus, the resistance of the circuit, which is indicative of liquid level, depends on the position of the float and the particular reed switch that has been tripped.
Although improvements to reed switches have been made over the years, they still suffer several drawbacks, the most prevalent of which may be their fragile nature as they are typically constructed of a sealed glass housing and two contacts positioned on ferrous metal reeds within the housing. Both the housing material and the small size of the contacts and reeds are subjected to breakage when sufficient vibrational and/or impact forces are applied. Once breakage of one or more reed switches occurs, the transducer may no longer be functional and thus may need replacement.
In addition, prior art liquid level transducers that include a mounting head and an elongate sensor probe, such as a reed switch probe, resistor probe, capacitor probe, and so on, are often difficult and time-consuming to assemble due to the number of individual components and the fastening means associated with each component.
It would therefore be desirable to overcome at least some of the disadvantages associated with electronic assemblies including prior art reed switch-type liquid level transducers. It would also be desirable to provide an electronic assembly, including a liquid level transducer, that is easier to assemble and has relatively fewer parts.
In accordance with one aspect of the invention, a transducer for determining the level of liquid within a container includes a mounting head adapted for connection to the container; a sensor tube extending from the mounting head; a substrate located in the sensor tube; at least one sensor positioned on the substrate for sensing a level of liquid within the container; and at least one damping section having at least one damping beam integrally formed with the substrate and partially separated therefrom by a slot formed between the at least one damping beam and the substrate. The at least one damping beam is normally in contact with a surface associated with the sensor tube and is movable toward and away from the substrate to dampen forces acting on the transducer and thus on the at least one sensor.
In accordance with a further aspect of the invention, an electronic assembly includes a substrate for receiving at least one electronic component; at least one damping section integrally formed with the substrate and including at least one slot formed in the substrate and at least one damping beam partially separated from the substrate by the at least one slot. The at least one damping beam is adapted to flex when the electronic assembly is exposed to outside forces to thereby dampen resultant forces acting on the substrate.
In accordance with yet another aspect of the invention, a method of damping an electronic assembly includes providing a substrate with at least one electrical property; forming a slot in the substrate to define at least a portion of a damping beam integrally connected to the substrate; exposing the electronic assembly to an outside force; and flexing the damping beam toward and away from the substrate to thereby dampen a resultant force on the substrate.
Other aspects of the invention will become evident upon considering the following detailed description of the preferred embodiments of the invention in conjunction with the accompanying drawings.
The following detailed description of the preferred embodiments of the present invention will be best understood when considered in conjunction with the accompanying drawings, wherein like designations denote like elements throughout the drawings, and wherein:
It is noted that the drawings are intended to depict only exemplary embodiments of the invention and therefore should not be considered as limiting the scope thereof. It is further noted that the drawings are not necessarily to scale. The invention will now be described in greater detail with reference to the accompanying drawings.
Referring now to the drawings, and to
The mounting head 14 preferably includes a mounting flange 15 extending radially outwardly from an annular side wall 18 that forms a hollow interior 19 (
It will be understood that the mounting head 14 is not limited to a flange mounting arrangement as shown, as other means for mounting the liquid level transducer 10 to a tank or other container can be used, including NPT type threads, clamping, welding, and so on, without departing from the spirit and scope of the invention. Moreover, the mounting head 14 can be constructed of a molded material, such as plastic, through injection molding or other techniques. However it will be understood that the mounting head 14 can be constructed of metal, composites, ceramics, combinations thereof; or any other suitable material.
As best shown in
Referring now to
The substrate 42, embodied as a PCB, can include traces, ground planes, and so on, for connecting various electronic components, such components being selected based on their suitability for intended functions. In this particular exemplary embodiment, the PCB 42 is populated with a plurality of normally-open reed switches 44 (
The reed switches 44 can be oriented at an acute angle with respect to a longitudinal axis of the sensor tube 30, as better switching performance has been achieved in this manner. However, the reed switches can be in any suitable orientation as long as they are responsive to the magnetic float 28 for creating a liquid level signal, in conjunction with the resistors 42 as previously described, as the float 28 rides along the outer sensor guide tube 20 in response to a change in liquid level within the container.
Although a representative number of reed switches and spacing therebetween are shown within the first section 50 of the substrate 42 in FIG.2, it will be understood that more or less reed switches can be provided at equal or varying spacing without departing from the spirit and scope of the invention. In instances where it may be more desirable to know how fast the container is approaching a full level during a filling operation to cut off a filling pump or the like, more sensors can be positioned closer together at the top of the first section 50 of the substrate 42 so that the liquid level can be more precisely and quickly determined at the top of the container. To that end, it may be desirable to reduce the number of sensors along the substrate 42. Likewise, in the event where it may be more important to determine how fast the container is approaching empty, it will be understood that more sensors can be located at the lower end of the first section 50 of the substrate 42, and thus the lower end of the container.
Moreover, although a reed switch-type arrangement on the PCB 42 has been shown and described, it will be understood that the present invention is not limited thereto. Other sensor(s) can be used without departing from the spirit and scope of the invention, including, but not limited to, hall-effect devices spaced at longer intervals along the substrate 42, other magnetic sensing probe technologies such as solid state magnetic flux field sensors (MR or GMR) magnetostrictive probe devices, solid state Micro-Electro-Mechanical Systems (MEMS), magnetic switches, as well as nonmagnetic sensing technologies such as optical sensors, mechanical switches, other electrical or mechanical position sensors, capacitance, and so on.
When Hall-effect, MR or GMR sensors are used for example, a single sensor can be placed at a single location or at a plurality of locations along the substrate 42. For instance, the single sensor can be placed at or near the top of the substrate 42 for detecting when the container is approaching a full condition. In addition or alternatively, a sensor can be placed on the substrate 42 at approximately a middle portion thereof for determining when the liquid in the container reaches the half-way point. Likewise, a sensor can be positioned on the substrate 42 at or near the bottom of the container for determining when the container is approaching an empty condition and/or when a filling operation has commenced.
The float 38 preferably includes a cylindrical body 44 to match the cylindrical shape of the sensor tube 30 and is constructed of a rigid material, such as closed-cell nitrile material, rubber, plastics, and so on. However, it will be understood that the shapes of the float, sensor tube 30, the mounting head assembly, and so on, are given by way of example only, as other suitable shapes, such as square, triangular, and so on, can be used without departing from the spirit and scope of the invention.
As best shown in
Referring again to
The first damping section 50 preferably includes a first set of damping members or beams 64 that are integrally formed with the substrate 42 and partially separated therefrom by a first slot 67 formed in the substrate so that the first beams 64 cantilever upwardly and slightly outwardly from a first longitudinal edge 68, which as viewed in
The damping beams 64 and 66 are in normal contact against opposite sides of the inner surface 72 (
In use, lateral impact or vibrational forces are transmitted to the liquid level transducer 10, either directly or indirectly, through structure connected to the liquid level transducer, such structure forming part of a machine or the like. Such lateral forces may occur for example when the structure or transducer hits or is hit by a solid object, starts suddenly with a jerk or stops suddenly, as well as other events that may cause lateral forces to act on the transducer 10. These transmitted forces are dampened by the beams 64 and 66 as they flex toward and away from their respective edges 68 and 70, to thereby dampen vibrational movement of the substrate 42 in the lateral direction as represented by arrow 58 (
The second damping section 54 also includes a plurality of damping members or beams 74 integrally formed with the substrate 42 and connected to each other in cantilever fashion via integral links 76 that alternately extend between adjacent ends of damping members 74 separated by first slots 75 extending from left to right in
The integral nature of the damping beams 74 and links 76 with the substrate 42 create an opposing biasing force when shock or vibration is transmitted to the lower end of the liquid level transducer 10 in a longitudinal direction, e.g. in a direction parallel with the longitudinal axis 65. The damping structure 72 normally rests against an upper surface 78 (
As shown in
Referring again to
The substrate areas 82, which also serve to dampen the substrate 42, can be populated with electronic components, connectors, and so on. Likewise, the damping beams 80 can carry electrical traces, ground planes, and so on, for transferring signals and power through the third damping section 56.
The integral nature of the damping beams 80 and areas 82 with the substrate 42 create an opposing biasing force when shock or vibration is transmitted to the upper end of the liquid level transducer 10. The upper end 88 of the substrate 42 can be restrained by additional structure (not shown) associated with the mounting head 14 or sensor tube 30. The upper end 88 can alternatively be left free of restraint to accommodate and provide a dampening effect for cable connectors (not shown) or other components located at the upper end of the substrate 42. The damping members 80 extend generally parallel to each other and perpendicular to the axis 65 to dampen longitudinal forces acting on the substrate 42. However, it will be understood that the slots, and thus the damping members 80, can be oriented at various angles to vary the location and intensity of stress within the third damping section 56.
The fourth damping section 57 includes narrowing neck portions beginning at the lower end of the PCB as designated by numeral 59, then continuing with a pair of distinct narrow neck portions 61 and 63 in a downward direction, or as the PCB approaches the second damping section 54. The decreasing widths of the narrowing neck portions 61 and 63 serve to disperse the reflected shock wave over time, thus decreasing the amplitude of the shock wave at any particular time. This is accomplished via reflecting part of the shock wave propagating from top to bottom of the PCB along the outside edge thereof, then reflecting the part of the shock wave propagating from the top to the bottom of the PCB at the center of the PCB. Thus a single high-amplitude shock wave is divided into two lower amplitude shock waves which are separated by a short period of time. The separation time is proportional to the speed of the shock wave through the PCB, as well as the separation distance between the two narrowing neck portions 61 and 63 of the PCB. It will be understood that more or less narrowing neck portions can be formed on the PCB without departing from the spirit and scope of the invention.
With the above-described PCB configuration, the present invention is capable of reducing or managing shock on the PCB and any components mounted thereto via three different mechanisms. These mechanisms include damping, reflection and dispersion. As shown in
It will be understood that the present invention is not limited to the particular shape and configuration as shown and described, as the shape of the substrate or PCB can greatly vary as well as the size, configuration, and location of the damping members and the damping sections. One or more damping sections can be eliminated and more sections can be added depending on particular damping requirements as dictated by the machinery or device with which the PCB or substrate is associated, without departing from the spirit and scope of the invention.
Referring now to
The electronic assembly 90 preferably includes a generally square-shaped and relatively thin substrate 92, preferably configured as a PCB with conductive traces, ground planes, and so on located on a main body portion 138 of the substrate. As in the previous embodiment, the substrate can be formed of a variety of different materials or combinations thereof, and can be formed as a single layer or with multiple layers. Various electronic components 94 can be located on the main body portion 138 of the PCB or otherwise connected thereto and can include basic components such as surface-mount or thru-hole electronic devices such as, but not limited to, capacitors, resistors, inductors, transistors, relays, voltage regulators, and so on, as well as more advanced electronic components such as microprocessors, display drivers, displays, conventional and specialty chips, timers, and so on.
It will be understood that the invention is not limited to particular electronic components or circuitry as such components and circuitry can greatly vary depending on particular application specific devices. The invention does, however, reduce forces acting on the components due to acceleration, deceleration, sudden impact, as well as variable and steady vibrations and other movement that may generate forces that could otherwise negatively impact the integrity of the electronic assembly 90. To that end, damping sections 96, 98, 100, and 102 are positioned proximal to respective corners 104, 106, 108, and 110 of the substrate 92. Preferably, the damping sections also provide a mounting arrangement for connecting the substrate or PCB to devices, machines, or structures incorporating the electronic assembly 90.
The damping sections 96, 98, 100, and 102 are similar in construction and, for the purpose of brevity, only damping section 100 will be described, with like elements of each of the remaining damping sections being similarly labeled. The damping section 100 includes a connector area 111 integral with and partially separated from the main body portion 138, and includes a centrally located opening 112 extending therethrough for slidably receiving a spacer 114 (
Although four spacers/fasteners are shown, it will be understood that more or less spacers and/or fasteners can be provided at the same or different locations without departing from the spirit and scope of the invention. Moreover, it will be understood that the PCB can be of any suitable shape for a particular application, and thus is not limited to the square shape or to corners as shown and described.
As best shown in
In use, the damping beams 130, 132, 134, and 136 flex under applied forces transmitted through structure connected to the damping section 100 and the damping sections 96, 98, and 102 to thereby dampen the main body portion 138 and electronics and/or other components mounted thereto. The connector area 111 of each damping section will typically remain relatively static with respect to the structure on which it is mounted when the substrate or electronic assembly 90 is subjected to acceleration forces due to vibration, sudden impact, and so on. The integral nature of the damping beams 130, 132, 134, and 136 with the substrate 92 create an opposing biasing force when shock or vibration is transmitted perpendicular to the substrate 92, and may also accommodate shock or vibration transmitted in a plane parallel to the substrate 92.
It will be understood that the beams are not limited to the size and shape as shown, but are defined by the size, shape, and relative placement of the inner and outer pairs of slots, as well as the length and width of the depressions 139. Accordingly, the configuration and size of the beams can vary depending on the amount of damping in one or more directions that is required for a particular application.
It will be understood that the particular configuration of the damping sections is by way of example only and can vary by varying the number of slots, the relative location of slots, as well as their orientation, size, and shape, in accordance with the present invention. It will be further understood that more or less damping sections can be provided, and that the shape of the substrate or PCB can greatly vary.
Moreover, one or more damping sections of the previous embodiment shown in
It will be understood, therefore, that the invention is not limited to the particular embodiments disclosed, but is intended to cover all modifications and variations within the spirit and scope of the present invention as defined by the appended claims.
It will be further understood that terms of orientation and/or position refer to relative, rather than absolute orientations and/or positions.
