Embodiments are generally related to sensing devices and in particular, to surface acoustic wave (SAW) sensors that measure the mechanical qualities of various structures. Embodiments are additionally related to sensing devices utilized in torque detection.
Passive sensors employing acoustic wave components for measuring torque are well known in the art. Torque measurement devices are an emerging technology with varied applications in automotive, transportation, rail and other similar segments for use in transmission and chassis applications, to name a few. Acoustic wave sensors are so named because they use a mechanical or acoustic wave as the sensing mechanism. As the acoustic wave propagates through or on the surface of the material, any changes to the characteristics of the propagation path affect the velocity, phase, and/or amplitude of the wave.
Working at very high frequencies, these extremely high-quality value (high Q value) sensing devices can be wirelessly excited with an interrogation pulse and a resonant frequency response measured allowing strain to be calculated. Torque can be sensed by using appropriate packaging and algorithms to deduce the value of the sensed property from the returned signal. These devices are cost-effective to manufacture, remarkably stable, and offer significantly higher performance than their 20th century, resistance gauge counterparts.
Unlike a conventional wire strain gauge, an acoustic wave torque sensor can store energy mechanically. Once supplied with a specified amount of energy (e.g., via radio frequency), these devices can function without cumbersome oscillators or auxiliary power sources. This capability has been exploited in many wireless/passive sensing operations, such as tire pressure sensors, and optimization of power-train efficiency.
When an acoustic wave device is used in sensor applications, the effect of an electric pulse applied to the inter-digital transducers (IDTs) is to cause the device to act as a transducer. The electric signal is converted to an acoustic wave which is transmitted via the piezoelectric substrate to the other IDTs. Upon arrival of the acoustic wave at the IDTs, the transducing process is reversed and an electric signal is generated. This output signal has a characteristic resonant frequency, or delay time which is dependent upon a number of factors including the geometry of the IDT spacing. Since the IDT spacing varies with strain/stress when the substrate is deformed, any change in this condition can be monitored by measuring the acoustic wave device frequency or delay time.
One of the problems with currently implemented torque sensors is the effect on the utilized SAW die of out-of-plane forces during torque sensing operations. Such out-of-plane forces tend to damage the resulting torque sensor, or at the very least, result in numerous torque sensor error readings. A need therefore exists for an improved apparatus or method for eliminating or minimizing such an effect on a SAW die utilized in torque sensor devices.
The following summary of the invention is provided to facilitate an understanding of some of the innovative features unique to the present invention and is not intended to be a full description. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
It is, therefore, one aspect of the present invention is to provide for an improved sensing device and method.
It is another aspect of the present invention to provide for an improved torque sensor apparatus.
The aforementioned aspects of the invention and other objectives and advantages can now be achieved as described herein. A torque sensor is disclosed based on a SAW die configured on a surface of a plate, and an isolator formed from a flexible material. The isolator is rigidly mounted to the plate, such that the isolator flexes when a force perpendicular to the surface of the plate are applied while transferring a torque that is applied within a plane of the plate to the SAW die, thereby eliminating or minimizing the effect on the SAW die of out-of-plane forces on the plate so as to isolate the torque transferred to the plate.
The torque sensor described herein eliminates or minimizes the effect of a SAW die of out-of-plane forces on a plate or disk so as to isolate the true torque transferred through the plate. The SAW die can then be mounted in the path of the isolated torque. Such a torque sensor solves the problem the aforementioned problem by placing the SAW die on an isolator device that is rigidly mounted to the plate by welding, bolding, pinning, etc., with attachment end points located along the radius of the plate and in the torque path. The isolator can be configured, such that it can flex freely in the direction of the out-of-plane forces, while remaining rigid in the path of the torque.
The isolator can be configured from a thin or necked down material that flexes, and therefore isolates, when forces perpendicular to the surface of the plate are applied while transferring force (e.g., torque) that is applied within the plane of the plate or disk to the SAW die. The isolator can be constructed either integral to the RF coupler or separate from it.
The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention.
The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate at least one embodiment of the present invention and are not intended to limit the scope of the invention.
Holes 106, 108, 110, 112, 114 and 116 can function as through holes and can be optionally utilized, depending on design goals. Holes 124, 126, and 128, on the other hand, can constitute flex plate to torque converter mounting holes. A group of flex plate to crank mounting holes 121, 123, 135, 127, 129, and 123 can also be provided at a central portion 118 that is located centrally within circular portion 104. Flex plate 100 is thus illustrated as an example of a flexible component that can be utilized to transmit torque, depending on design considerations.
An isolator 204 can be provided, which is formed from a flexible material. The isolator 204 is rigidly mounted to the plate 100 depicted in
Torque is depicted by arrows 302, 304 illustrated in
It will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
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