Patent Application
20070028700
Embodiments are generally related to sensor devices, systems and methods and, in particular, to acoustic wave sensor devices, systems and methods. Embodiments are additionally related to passive acoustic wave sensor devices, such as, for example, surface acoustic wave (SAW) devices and sensors that measure mechanical qualities of various structures. Embodiments are additionally related to wireless 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.
A known method of measuring torque in a shaft or other torque transmitting component through use of an acoustic wave device is described in can be mounted using an adhesive on the base and the acoustic wave torque sensors are then permanently welded onto the shaft.
In summary, the device and accompanying methods disclosed herein can extend the functional life of these acoustic wave torque sensors, resulting in a reduction in overall cost to consumer, while promoting an increase in sensing efficiency.
The following summary is provided to facilitate an understanding of some of the innovative features unique to the embodiments and is not intended to be a full description. A full appreciation of the (various aspects of the embodiments can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
It is, therefore, one aspect of the embodiments to provide for improved torque sensing devices, systems, and methods.
It is another aspect of the embodiments to provide for a torque measurement device and/or system, which can be removably attached to facilitate serviceability and replacement.
It is a further aspect of the embodiments to provide for a torque measurement system, which can be removably attached using a variably-shaped retainer, and one or more associated connectors.
The aforementioned aspects and other objectives and advantages can now be achieved as described herein. A torque measurement system is disclosed, which includes an acoustic wave sensor that is removably attached to a shaft, wherein a removal of the acoustic wave device with the variably-shaped retainer facilitates servicing and replacement of the torque measurement device. Other acoustic wave devices such as acoustic wave resonators, surface acoustic wave delay lines, surface transverse waves, and surface acoustic wave filters can also be removably attached to the rotatable shaft, depending upon design considerations and the specific goals of the torque detection system.
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 and are not intended to limit the scope thereof.
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Note that in general, It is preferred that the orientation of the SAW (filter, resonator or delay line) torque sensing element, or the IDTs of the SAW device (filter, resonator or delay line) are arranged at an angle to the axis of the shaft. Ideally, the angle should be 45 degrees. Additionally, it is important to note that the embodiments disclosed herein can be implemented in a wide variety of applications, including automotive, transportation, rail and other similar segments for use in transmission and chassis applications, among others.
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.
The embodiments of the invention in which an exclusive property or right is claimed are defined as follows.
