This disclosure relates generally to detecting vehicle weight and, more particularly, to methods and apparatus to detect load applied to a vehicle suspension.
In recent years, determining a weight of a vehicle has become increasingly sophisticated. For example, some systems determine a weight of a vehicle based on a measured pressure applied to a suspension. In some examples, vehicle suspension systems include load sensing devices that measure pressure.
An example apparatus includes a vehicle spring positioned between a first spring seat and a second spring seat. A cap is coupled to the first spring seat to define a cavity. A force sensor is positioned in the cavity adjacent a surface of the first spring seat.
An example apparatus including a spring seat, means for biasing, and a force sensor positioned between the spring seat and the means for biasing.
An example apparatus including means for biasing positioned between a first spring seat and a second spring seat. A cap coupled to the first spring seat to define a cavity. An isolator positioned in the cavity. The example apparatus also includes means for sensing a force positioned in the cavity adjacent a surface of the first spring seat.
The figures are not to scale. Wherever possible, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts.
Some known vehicles employ measuring apparatus to detect or measure a vehicle weight. Some known example vehicles employ sensors that are integrated with a vehicle suspension. Integrating a sensor with a suspension system is beneficial because a total weight of the vehicle is sensed through the suspension.
Some known vehicle suspensions employ measuring apparatus that measure a pressure applied to an airbag suspension system to determine vehicle weight. Some known vehicle suspension systems include loading apparatus that bend or deflect (e.g., relative to a flat or initial position) to measure a bending force to detect or measure vehicle weight. As a result of the size and/or packaging constraints of such loading apparatus, in some instances, significant modification of preexisting suspension geometries may be needed to avoid changing (e.g., raising) a vehicle ride height and/or handling characteristic of a vehicle. In some cases, modifications necessary to implement such loading apparatus can double the number of suspension components, increasing manufacturing costs.
Examples disclosed herein provide an efficient, low-profile solution to determine vehicle weight across multiple platforms without the need to design different suspension architectures. Example suspensions disclosed herein employ a force sensor (e.g., a thin-film transducer) to sense an applied force to the vehicle suspensions. For example, when a load is applied to the suspensions, example sensors disclosed herein produce an electrical signal (e.g., a voltage, a change in resistance, a change in capacitance, etc.) based on amount of force or pressure applied to the suspensions and/or the sensors. Some example sensors disclosed herein may be formed from Quantum Tunneling Composites (e.g., composite materials of metals, non-conducting elastomeric binders, etc.) that allow for the production of thin sensors.
Additionally, example sensors disclosed herein may have different configurations to accommodate different types of vehicle suspensions (e.g., a MacPherson strut, a leaf spring suspension, etc.). For example, example sensors disclosed herein may have a rectangular shape, a circular shape, and/or any other shape. In some instances, a shape or profile of an example sensor disclosed herein may improve sensing accuracy.
Some example sensors disclosed herein may be isolated between a first side by a spring seat (e.g., that provides natural resistance to shock and environmental conditions) and a second side of the spring seat by a rubber isolator. Isolation of the sensor enables the sensor to more accurately sense a weight of a vehicle. As such, the example sensors disclosed herein improve electronic stability control, accuracy in driveline calibration, algorithms based on vehicle weight distribution, autonomous vehicle systems, and information provided to a driver to reduce unbalanced driving. Some example sensors disclosed herein may be printed or formed directly onto a spring seat or an upper strut surface of a suspension. For example, sensors disclosed herein may be printed onto the spring seat using heat molding manufacturing processes or techniques. Printing an example sensor directly onto a suspension component reduces part count.
The teachings of this disclosure may be implemented with any type of suspension (e.g., a steerable suspension, a non-steerable suspension, a MacPherson strut, a Short Long Arms suspension) for use with any types of vehicles.
The suspension 200 of the illustrated example is an example coil-spring suspension (e.g., a MacPherson strut). The suspension 200 of the illustrated example includes a shock absorber 202. The shock absorber 202 includes a first end 204 (e.g., a piston end) coupled to a frame 206 of the vehicle 100 adjacent the wheel 102 and a second end 208 (e.g., a housing) coupled to a suspension control link 210 of the suspension 200.
During operation, the suspension 200 (e.g., the shock absorber 202) of the illustrated example controls unwanted motion of the vehicle 100 by reducing a magnitude of vibratory motion. The example suspension 200 of the illustrated example gradually dissipates forces generated when the wheel (e.g., the wheel 102) traverses a bump, pothole, and or other road surface anomalies in a controlled manner that helps a driver maintain control over the vehicle 100 and/or provide the driver with a comfortable driving environment.
Additionally, the suspension 200 of the illustrated example measures a load applied to the suspension 200. For example, the shock absorber 202 of the illustrated example measures and/or detects a first load or force 212 applied in a direction between the first end 204 and the second end 208 (e.g., along a longitudinal axis) of the shock absorber 202. For example, the shock absorber 202 of the illustrated example receives the force 212 applied to the shock absorber 202 in a direction parallel to the longitudinal axis of the shock absorber 202. When the vehicle 100 receives a load, the shock absorber 202 of the illustrated example absorbs (e.g., damps) and/or dissipates forces and the associated energy to reduce discomfort of a driver of the vehicle 100.
To cover or protect the piston rod 302 from damage and/or debris, the suspension 200 of the illustrated example includes a cap 322. The cap 322 of the illustrated example couples to the body 310 of the first spring seat 306. The cap 322 of the illustrated example includes an annular wall 324 (e.g., a circumferential wall) to define a cavity 326. The cap 322 of the illustrated example includes a second boss 328 positioned in the cavity 326 and having an opening 330 to receive the piston rod 302.
To measure a load (e.g. the force 212 of
To mitigate the sensor 332 from moving or displacing relative to the second surface 314, the suspension 200 of the illustrated example includes an isolator 336 (e.g., a rubber isolator). The isolator 336 includes an opening 338 (e.g., a central hole) to receive the piston rod 302 and an annular flange 340 defining a cavity 342 to receive the sensor 332. In some examples, the suspension 200 may not include the isolator 336.
To assemble the suspension 200, the sensor 332 is positioned on the second surface 314 of the first spring seat 306. The first boss 318 of the illustrated example may guide placement of the sensor 332 on the first spring seat 306. The isolator 336 is positioned on the sensor 332 and the cap 322 is coupled to the first spring seat 306. The cap 322 and the first spring seat 306 of the illustrated example define a cavity 344 to receive the isolator 336 and the sensor 332 when the cap 322 is coupled to the first spring seat 306. Additionally, the second boss 328 of the cap 322 of the illustrated example is adjacent (e.g., enjoins or couples to) the first boss 318 of the first spring seat 306 to provide a support or guide for the piston rod 302. The cap 322 and the first spring seat 306 of the illustrated example form or provide a tight seal to prevent debris or contaminates from entering the cavity 344 and/or the sensor 332. The sensor 332 of the illustrated example does not deflect to sense a load. Additionally, the isolator 336 and the sensor 332 of the illustrated example are relatively thin (e.g., 1 millimeter, 2 millimeters, 3 millimeters, etc.) so that a ride height of the vehicle 100 is not meaningfully altered (e.g., increased or decreased), and the components of the suspension 200 do not need to be modified. Thus, the sensor 332 provides a relatively low profile that does not require modification of the shock absorber 202 such that the example sensor 332 may be implemented with an existing shock absorber (e.g., an off-the-shelf shock absorber) and the sensor 332 will not meaningfully affect or vary (e.g., increase or decrease) a ride height of a vehicle.
During operation, a load provided to the wheel 102 imparts a load on the suspension 200. The sensor 332 of the illustrated example senses the load and produces (e.g., outputs) an electrical signal that corresponds to a magnitude of the load. The control system 110 (
To correlate outputs (e.g., electrical signals) of the sensor 332 to loads, the sensor 332 of the illustrated example is calibrated prior to installation on the suspension 200. For example, various known loads are applied to the sensor 332 (e.g., during a bench test). The resulting electrical signals produced by the sensor 332 are measured and a calibration curve is produced, indicating the correspondence between the applied load and the produced electrical signal. It is beneficial to calibrate the sensor 332 because some sensors are prone to calibration shift over time when the load distribution is not even (e.g., the resistive material migrates through the substrates to less-loaded areas). However, the disclosed configuration helps mitigate calibration shift because the sensor 332 is enclosed by the isolator 336, the first spring seat 306 and/or the first boss 318, which helps distribute the load and capture the entire load through the load path of the vehicle suspension 200.
The sensor 332 of the illustrated example may include one or more traces (e.g., electrical traces) to sense a force applied to the sensor 332. In some examples, the sensor 332 can detect a force without bending. In other words, the sensor 332 remains substantially flat (e.g., remains within 10% deflection from a plane of the thickness 408) when a force is applied to the sensor.
To manufacture the sensor 332 of the illustrated example, measurements are taken of the suspension component that is to house the sensor 332. For example, the sensor 332 is formed such that the first radius 404 and the second radius 406 are substantially similar (e.g., slightly smaller than) the second surface 314 of the first spring seat 306 and the diameter of the first boss 318. The sensor 332 of the illustrated example may be formed from Quantum Tunneling Composites, piezoelectric materials, piezo resistive materials, etc., that allow for the production of thin sensors. For example, the sensor 332 may be formed from a piezoelectric film pressed between two electrodes (e.g., copper) surrounded by a protective coating (e.g., polyethylene). In some examples, the sensor 332 may be a thin film transducer. In some examples, the sensor 332 may be printed onto the second surface 314 of the first spring seat 306 using, for example, heat molding manufacturing processes or techniques.
During operation, the biasing element 502 deflects in response to forces generated when the wheels 106, 108 (
To couple the biasing element 502 to the spring seat 506, the suspension 500 includes the bracket 508. The bracket 508 of the illustrated example includes a first portion 614 and a second portion 616 removably coupled to the first portion 614. The first portion 614 of the illustrated example includes apertures 618 to receive the second portion 616. In the illustrated example, the first portion 614 includes a recessed area 620 to engage the axle 504. The second portion 616 of the illustrated example includes the fasteners 608 and a plate 622. The plate 622 of the illustrated example includes a top bracket 624 to couple the U-bolts 512, 514 to the plate 622. The top bracket 624 of the illustrated example includes a tongue 628 and a recess 630 to receive the U-bolt 514. For example, to receive the U-bolt 514, the tongue 628 is elevated and the U-bolt 514 is placed in the recess 630. The tongue 628 is lowered to secure the U-bolt 514 in the recess 630.
To measure a load applied to the vehicle 100, the suspension 500 of the illustrated example includes a sensor (e.g., a force sensor) 632. The sensor 632 of the illustrated example is positioned on the first surface 610 of the spring seat 506. In the illustrated example, the sensor 632 includes openings 634 to receive the fasteners 608 to enable the fasteners 608 to engage or couple to the spring seat 506. In some examples, the sensor 632 does not include the openings 634 when the fasteners 608 do not engage or couple to the spring seat 506. Alternatively, in some examples, the sensor 632 may be printed onto the first surface 610 of the spring seat 506 to reduce parts count.
To assemble the suspension 500, the sensor 632 is positioned on the first surface 610 of the spring seat 506. The biasing element 502 is positioned on the sensor 632 and the bracket 508 couples the biasing element 502 to the spring seat 506. In the illustrated example, the sensor 632 is thin (e.g., 1 millimeter, 2 millimeters, 3 millimeters, etc.) so that the ride height of the vehicle 100 is not meaningfully changed, and the components of the suspension 500 do not need to be modified in any way. The sensor 632 functions or operates substantially similar to the sensor 332 of the example suspension 200 of
To manufacture the sensor 632 of the illustrated example, measurements are taken of the suspension component that will house the sensor 632. For example, the example sensor 632 is formed to be substantially similar (e.g., slightly smaller than) the first surface 610 of the spring seat 506. The sensor 632 of the illustrated example may be formed from Quantum Tunneling Composites, piezoelectric materials, piezo resistive materials, etc., that allow for the production of thin sensors. For example, the example sensor 632 may be formed from a piezoelectric film pressed between two electrodes (e.g., copper) surrounded by a protective coating (e.g., polyethylene). In some examples, the example sensor 632 may be printed onto the first surface 610 of the spring seat 506 using, for example, heat molding manufacturing processes or techniques.
The example method 800 begins when the sensor 332 is positioned on a surface of the first spring seat 306 (block 802). For example, positioning the sensor 332 on the surface 314 of the first spring seat 306. The isolator 336 is positioned on the sensor 332 (block 804). The cap 322 is then coupled to the spring seat 306 (block 806).
Referring to
From the foregoing, it will be appreciated that example methods, apparatus and articles of manufacture have been disclosed that enable an efficient, low-profile solution to measure vehicle weight across multiple platforms without the need to design for multiple suspension architectures. The examples disclosed are beneficial because these examples utilize thin sensors that can be implemented with (e.g., installed in) existing suspensions requiring minimal change to manufacturing and assembly of the suspensions. Additionally, the sensors disclosed herein are relatively thin and may increase a ride height by less than one millimeter. The examples disclosed are capable of being used across multiple platforms of the vehicle other than suspensions. For example, under a bed of a vehicle. The disclosed examples increase resistance to environmental factors (e.g., temperature, humidity, shock) and these examples are cost and weight efficient. In addition, the disclosed examples improve electronic stability control, accuracy in driveline calibration, algorithms based on vehicle weight distribution, autonomous vehicle systems, and information provided to driver to reduce unbalanced driving.
Although certain example methods, apparatus and articles of manufacture have been disclosed herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the claims of this patent.