Height sensing system for a vehicular suspension assembly

A system is provided for determining a distance between a vehicular suspension assembly and the ground, wherein the suspension assembly has a first member. The system comprises a first transceiver coupled to the first member for emitting a first interrogation signal toward the ground, and for receiving a first reflection of the first interrogation signal from the ground, and a processor coupled to the first transceiver for determining the distance of the first transceiver from the ground.

TECHNICAL FIELD

The present invention generally relates to vehicular suspension assemblies, and more particularly relates to a height sensing system integrated into a vehicular suspension assembly.

BACKGROUND OF THE INVENTION

Control systems that automatically regulate ride height and suspension damping have been integrated into the suspensions of many vehicles. These systems rely on height sensors to provide real-time feedback on the distance between selected suspension components, or relative height, of sprung and unsprung vehicle masses. This data may be relayed to controllers that respond to relative height variations by adjusting compensating elements in the suspension to provide greater chassis stability. Accuracy in relative height measurement enables a more precise system response and thereby enhances vehicle performance characteristics including ride comfort and handling especially during cornering, accelerating, and braking.

Typical relative height sensors use mechanical linkages connected between monitoring points in the suspension that convert linear displacement to an angular motion. A contacting or non-contacting, electro-mechanical sensor converts this angular displacement to an electrical signal indicative of the height differential. However, such systems often include mounting arms, sensor links and brackets, and a myriad of associated connecting fasteners and therefore increase part count and complicate assembly and servicing. Further, the exposure of these systems to the undercarriage of a vehicle increases their vulnerability to contamination and road debris that can cause damage and/or degrade long term performance and reliability. In addition, current systems do not determine the absolute height of a vehicle, that is, the distance between selected chassis components and the ground.

Accordingly, it is desirable to provide a height sensing system for use in conjunction with a vehicular suspension assembly that determines the distance between selected suspension monitoring points and the ground. Further, it is also desirable if such a system is simpler to assemble, more convenient to service, and has a reduced part count. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.

SUMMARY OF THE INVENTION

In accordance with an embodiment, by way of example only, a system is provided for determining a distance between a vehicular suspension assembly and the ground, wherein the suspension assembly has a first member. The system comprises a first transceiver coupled to the first member for emitting a first interrogation signal toward the ground, and for receiving a first reflection of the first interrogation signal from the ground, and a processor coupled to the first transceiver for determining the distance of the first transceiver from the ground.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT

The various embodiments of the present invention described herein provide an electronic height sensing system for a vehicular suspension. The system includes one or more transceivers each coupled to a component of a vehicular suspension assembly for monitoring the height thereof. Each transceiver is configured to sense the “absolute” height, or the vertical distance between the transceiver and the ground. When the system is configured with two or more transceivers, the “relative” height, or the difference in vertical distance between any two transceivers may also be determined. As used herein, the absolute height of a transceiver, or the relative height between transceivers is not distinguished from the absolute or relative heights, respectively, of the suspension component that such transceivers are coupled to.

Relative height can be especially useful when referring to the distance between sprung and unsprung vehicle masses because of the important role this quantity plays in ride height and chassis control. Transceivers coupled to suspension components send electronic signals in the form of, for example, timing pulses or digitized data, indicative of absolute height to a coupled processor configured to use these signals in determining the actual height of the component. Such height data may then be relayed to a controller for use in adjusting controlled suspension elements to maintain the stability of a vehicle chassis and body for a variety of road surface conditions. In addition, height data may be used to determine the vertical component of absolute and/or relative velocity and acceleration of and/or between suspension components. This information may also be used by a chassis controller to further refine steering, cornering, accelerating, and braking performance.

FIG. 1is a plan view of a vehicle10(e.g., an automobile) for use in conjunction with one or more embodiments of the present invention. Vehicle10includes a chassis12, a body14, four wheels16, a suspension assembly22, and a chassis control module (or CCM)33. Body14is arranged on the chassis12and substantially encloses the other components of the vehicle10. Body14and chassis12may jointly form a frame. The wheels16are each rotationally coupled to chassis12near a respective corner of body14. Suspension assembly22is configured to provide a damped and stabilized coupling between a sprung vehicle mass including body14, and an unsprung mass including wheels16and part of chassis12. Suspension assembly22may include springs, linear actuators, control arms or links, and other interconnecting and supporting members, and further includes at least one damper assembly64such as a shock absorber or a strut, or the like, for providing damped motion between sprung and unsprung vehicle masses. Damper assemblies64may be configured to respond passively to vehicle motion, or as shown inFIG. 1, may be coupled to CCM33and configured to provide controlled suspension adjustments as directed thereby. As shown, vehicle10has four such damper assemblies64, each mechanically coupled to suspension assembly22proximate wheels16, and coupled in communication with CCM33.

Vehicle10may be any of a variety of vehicle types, such as, for example, a sedan, a wagon, a truck, or a sport utility vehicle (SUV), and may be two-wheel drive (2WD) (i.e., rear-wheel drive or front-wheel drive), four-wheel drive (4WD), or all-wheel drive (AWD). Vehicle10may also incorporate any one of, or combination of, a number of different types of engines, such as, for example, a gasoline or diesel fueled combustion engine, a “flex fuel vehicle” (FFV) engine (i.e., using a mixture of gasoline and alcohol), a gaseous compound (e.g., hydrogen and/or natural gas) fueled engine, or a fuel cell, a combustion/electric motor hybrid engine, and an electric motor.

Still referring toFIG. 1, chassis control module33is coupled in communication with various automotive sub-system sensors including a steering sensor30for determining steering direction, at least one lift/dive sensor34used to monitor chassis response to braking and accelerating, and a speed sensor38for measuring vehicle speed. CCM33also includes a user interface40whereby a driver may enter various system commands and receive therefrom other pertinent system information. CCM33is also coupled in communication with various transceivers used as vehicle height sensors mechanically coupled to body14, chassis12, and/or suspension assembly22for monitoring vehicle height including at least a first transceiver42. CCM33also includes at least a processor37for processing vehicle height information received from vehicle height sensors, and a controller35coupled to processor37for relaying electronic commands to controlled suspension components including, for example, damper assemblies64in response to processor prompts. During operation, vehicle height sensors monitor the distance between the ground and selected suspension, body, and/or chassis components, and transfer signals indicative of this distance to processor37. Processor37then converts these signals to data that may be used by controller35to make appropriate compensating chassis adjustments.

FIG. 2illustrates first transceiver42integrated into suspension assembly22of vehicle10(FIG. 1) in accordance with an exemplary embodiment. Suspension assembly22includes damper assembly64coupled between a sprung vehicle mass50and an unsprung vehicle mass70, and configured to dampen vertical motion therebetween in a well known manner. Damper assembly64has a first end coupled to a lower control arm68of unsprung mass70by a lower mount58, and a second end coupled to a frame structural member48of sprung mass50by an upper mount54. Mounting of damper assembly64to structural members and control arms may be done in any conventional manner using mounting brackets and fasteners. First transceiver42is an element of CCM33and is coupled in two-way communication with processor37(FIG. 1). First transceiver42may be mechanically coupled to any suitable component of suspension assembly22wherein it is desirable to monitor the component-to-ground height such as, for example, structural member48. During operation, first transceiver42emits interrogation signals toward the ground55when prompted by processor37, and detects the reflection of these interrogation signals returned from the ground55. Processor37records the time of prompting, and first transceiver42sends an electronic timing signal to processor37when the interrogation signals are detected.

The interrogation signals emitted by first transceiver42may be electromagnetic in nature and may include but are not limited to ultra wide band (UWB) radar, infrared (IR), or laser light radiation, or alternatively may comprise an ultrasonic sound wave. Processor37combines the time recorded when first transceiver42was prompted with a timing signal returned by first transceiver42indicative of the timing of interrogation signal detection to determine the total elapsed time between emission and detection. Processor37converts the elapsed times to an absolute distance from the component to the ground, D1, using for example, an algorithm that may include Equation (1) below:
D1=0.5c×[Δt1]  (1)
where c is the speed of propagation of the transmitted and reflected interrogation signals, and Δt1represents the time lapse between interrogation signal emission and detection by first transceiver42of the reflection of the interrogation signal. The final result may be modified to account for systemic errors such as time delays in timing signal transfer and the like.

First transceiver42is configured to emit and detect interrogation signals of a specific type or types, and comprises one of a variety of transmission/detection systems based upon either electromagnetic radiation or sound waves. In one embodiment, first transceiver42comprises a transmitter component configured to emit short duration UWB or radar pulses that may include wavelengths in the radio and/or microwave frequency ranges. One example of such a commercially available UWB transceiver is manufactured by Freescale Semiconductor bearing part number XS 100. The detection component of first transceiver42in this embodiment may be based upon RFCMOS (radio frequency, complementary metal oxide semiconductor) technology tuned for compatibility with the transmitter.

In another embodiment, first transceiver42is configured with semiconductor-based laser diodes that emit/detect radiation over a narrow range of wavelengths. The detection component for this transceiver may also be a semiconductor diode configured to detect light at the transmitted wavelength(s). In a further embodiment, first transceiver42is configured to emit IR radiation and preferably comprises a semiconductor light emitting diode (LED). This type of transceiver may also comprise a photodiode detector such as a PIN-type photodiode tuned to detect light of the emitted wavelengths. In yet a further embodiment, first transceiver42comprises an ultrasonic transducer configured to emit ultrasonic pressure waves. A transceiver of this type also includes a second pressure transducer tuned to detect these sound waves.

To aid in source recognition and mitigate the effects of stray radiation, each of the transceiver embodiments described above preferably emits a pulsed interrogation signal comprising short duration, electromagnetic or sound emissions. Interrogation signal pulse duration and/or cadence may be optimized to be compatible with an absolute height range characteristic of a vehicle suspension system. Further, when multiple transceivers are used in a suspension assembly as described further in following embodiments, interrogation signals may be varied between each transceiver to encode the signal and avoid confusion as to the correct source and mitigate the effects of stray light or other types of false signals. In another embodiment, first transceiver42may be equipped with a duplexer to aid in switching between transmission and detection at an appropriate predetermined rate.

FIG. 3is a block diagram of selected components of CCM33from vehicle10(FIG. 1) including first transceiver42, processor37, and controller35in accordance with an exemplary embodiment. Processor37is operatively coupled to controller35, and is coupled in two-way communication with first transceiver42. First transceiver42is configured to emit electromagnetic or ultrasonic interrogation signals toward the ground55when prompted by a signal, Sp1, from processor37, and to detect the reflection of these interrogation signals reflected from the ground55. Processor37then records the timing of this prompt and receives an electronic timing signal indicative of the timing of detection (td) from first transceiver42. Processor37uses the difference between the times of prompting and detection in conjunction with an appropriate equation/algorithm previously described to determine the distance of first transceiver42from the ground. Controller35receives the height data as an input signal from processor37, and may dispatch real-time commands to controlled suspension elements in response to current chassis conditions as reflected by this data.

FIG. 4illustrates a second transceiver46that may be used in conjunction with first transceiver42integrated into suspension assembly22in accordance with another exemplary embodiment. Second transceiver46is also an element of CCM33coupled in two-way communication with processor37(FIG. 1), and is one of the types of transceivers previously described for first transceiver42. Second transceiver46may be mechanically coupled to any suitable element of suspension assembly22wherein it is desirable to monitor distance to the ground, and preferably to an element different than that of first transceiver42. For example, as shown inFIG. 4, second transceiver46is mounted to lower control arm68of the unsprung vehicle mass70. During operation, first and second transceivers42and46each emit separate interrogation signals of a type described above toward the ground55when prompted by processor37. Each transceiver then detects the reflection of the interrogation signals emitted by the source transceiver reflected from the ground55.

First and second transceivers42and46may be used individually to monitor the absolute suspension component height at the respective location of each in a manner previously described, or may be used in combination to determine the relative height between suspension locations. For example, referring toFIG. 4, when mounted to sprung and unsprung masses50and70, the relative height between masses may be determined as equal to the difference in absolute heights between first and second transceivers42and46. To determine a relative height, processor37prompts first and second transceivers42and46to substantially simultaneously emit interrogation signals to the ground. Each transceiver responds by substantially simultaneously emitting an interrogation signal directed to the ground and detecting the reflection of the respective interrogation signal reflected therefrom. Processor37then records the time of prompting and receives from each transceiver a timing signal indicative of the time of detection for that transceiver. Processor37uses the prompt time combined with these timing signals to determine an actual elapsed time for each transceiver. Processor37then determines the absolute distance to the ground Ds(from sprung mass50) and Du(from unsprung mass70), for transceivers42and46, respectively, using for example, an algorithm that may include Equations (2) and (3) below:
Ds=0.5c×[Δts]  (2)
Du=0.5c×[Δtu]  (3)
where c is the speed of propagation of the transmitted interrogation signal, and Δtsand Δturepresent the elapsed time between emission and detection of interrogation signals originating from first and second transceivers42and46, respectively. The relative height between sprung and unsprung vehicle masses, Hsu, may then be determined using an algorithm that may include Equation (4) below:
Hsu=Ds−Du(4)
The final result may be modified for reasons previously described.

FIG. 5is a block diagram illustrating a manner in which selected elements of CCM33of vehicle10(FIG. 1) including first transceiver42, second transceiver46, processor37, and controller35interact in accordance with an exemplary embodiment. Processor37is operatively coupled to controller35, and coupled in two-way communication with both first and second transceivers42and46. Each transceiver is configured to emit electromagnetic or ultrasonic interrogation signals toward the ground55when prompted by processor37, and to detect the reflection of the source interrogation signals returned from the ground55. When first and second transceivers42and46are to be used in conjunction to determine a relative height therebetween, processor60prompts these transceivers to emit interrogation signals substantially simultaneously. Each transceiver then relays a timing signal indicative of the time of detection (td) to processor37. For example, processor37sends a first prompting signal, Sp1, to first transceiver42prompting it to emit an interrogation signal to the ground. First transceiver42emits a first interrogation signal and detects a reflection of the first interrogation signal from the ground and relays an electronic timing signal, td1, to processor37indicative of the time of detection. Similarly, processor37sends a second prompting signal, Sp2, to second transceiver46prompting it to emit a second interrogation signal toward the ground. Second transceiver46emits the second interrogation signal, detects its reflection, and relays another electronic timing signal, td2, to processor37. Processor37records the time of prompting and combines this time with these timing signals to determine the actual elapsed time between emission and detection for each transceiver. Processor37uses the elapsed times in conjunction with an appropriate algorithm previously described to determine the distance of each transceiver from the ground. Processor37may also determine the relative height, Hr, between transceivers by taking the difference in absolute heights D1(for first transceiver42) and D2(for second transceiver46) using an algorithm that may include equation (5) below:
Hr=D1−D2(5)
Controller35receives the resulting height data as an input signal from processor37, and may dispatch real-time commands to controlled suspension elements in response.

FIG. 6illustrates a suspension actuator100having first and second transceivers116and120, respectively, for determining the vertical distance of travel of actuator100in accordance with another exemplary embodiment. Suspension actuator100may be, for example, a passive actuator assembly such as a non-controllable shock absorber or strut, or a controllable actuator assembly such as a linear actuator, or a controllable shock absorber or strut. Suspension actuator100has a first portion128that may comprise a dust tube126coupled to first transceiver116and to a first suspension member108that may be a part of the sprung mass. Actuator100also has a second portion132that may comprise a damper tube134coupled to second transceiver120and to a second suspension member112that may be a part of the unsprung mass. Second portion132is fixed relative to first portion128which is movable in and out of second portion132in a well known manner. Those of skill in the art will appreciate that while actuator100is depicted as having damper and dust tubes, many other possible configurations are possible, and therefore this description is made as an example and without limitation. Further, actuator100may be coupled between any suitable suspension members without limitation as to whether such members are part of the sprung or unsprung masses.

The distance of travel of actuator100is defined as the amount of linear travel of first portion128with respect to a reference/zero position such as where first portion128is fully retracted within second portion132. The vertical component of the distance of travel is thus the difference in relative height for first and second transceivers116and120determined at the position of interest and the reference position.

First and second transceivers116and120may be any of the transceiver types previously described, and are each coupled in two-way communication with processor60. During operation, processor60sends substantially simultaneous prompting signals, Sp1and Sp2, to first and second transceivers116and120, respectively, to emit interrogation signals directed toward the ground55, and records the timing of prompting. Each transceiver emits interrogation signals substantially simultaneously and receives a reflection of the interrogation signals emitted by that transceiver from the ground55. First and second transceivers116and120each send timing signals td1and td2indicative of the timing of detection of each respective transceiver to processor60. Processor60is configured with algorithms described above for determining the relative height or the vertical component of distance between first and second transceivers116and120. The vertical component of the distance of travel, Dt1, at a time t1may be determined using algorithms that may include equation (6) below:
Dt1=Ht1−HR(6)
wherein HRis the relative height determined at the reference position, Ht1is the relative height determined at time t1. The final result may be modified to calibrate the system for such factors that include but are not limited to timing signal delay and/or actuator orientation.

Processor37may also be configured to determine additional information relating to the vertical component of the absolute velocity and acceleration of a single suspension component. For example, the absolute heights of a single suspension component, D1and D2, determined at two different times, t1and t2, may be used to determine the average vertical component of velocity Vaof that component using an algorithm that may include equation (7) below:

Va=[D2-D1][t2-t1](7)
Further, the instantaneous velocity, Vi1, of a single component at time t1may also be determined using an algorithm that may include equation (8) below:

Vi⁢⁢1=limt2→t1⁢[D2-D1][t2-t1](8)
Further, the instantaneous velocities, Vi1and Vi2, determined at two different times, t1and t2, may be used to determine the average vertical component of acceleration, Aa, of that component between t1and t2using an algorithm that may include equation (9) below:

Aa=[Vi⁢⁢2-Vi⁢⁢1][t2-t1](9)
The instantaneous acceleration, Ai1, of a single component at time t1then may be determined using an algorithm that may include equation (10) below:

Ai⁢⁢1=limt2→t1⁡[Vi⁢⁢2-Vi⁢⁢1t2-t1](10)
Processor37may also be configured to determine the instantaneous relative velocity and acceleration between suspension components C1and C2based upon height data. For example the instantaneous relative velocity, Vir, may be determined for a time t1by taking the difference in the instantaneous velocities, ViC1and ViC2, of each component at time t1using an algorithm that may include equations (11) below:
Vir=ViC2−ViC1(11)
The instantaneous relative acceleration, Ari, between suspension components C1and C2may be determined by taking the difference in the instantaneous accelerations, AiC1and AiC2, of each component using an algorithm that may include equation (12) below:
Ari=AiC2−AiC1(12)

The embodiments described herein provide a height sensing system for a vehicular suspension. Processor-controlled transceivers coupled to suspension component(s) to be monitored emit pulsed electromagnetic or ultrasonic interrogation signals and receive these interrogation signals reflected from the ground. A processor coupled to these transceivers converts the timing of emission and detection to a time differential and determines therefrom a corresponding absolute height. This system may also be used to determine the relative height between two suspension components or the vertical distance of travel of an actuator at a point in time by determining the difference in absolute heights between monitored points on each of these elements. Height data gathered over a time interval may be used to determine vertical components of both velocity and acceleration for an individual suspension component, or may be combined with similar data from a second suspension component to determine relative velocity and acceleration therebetween. Data relating to the absolute and relative, height, velocity, acceleration, and/or the vertical distance of travel of a suspension component may be relayed to a controller to provide a basis for on-the-fly chassis adjustments to enhance driving stability and handling performance.

The preceding description refers to elements or nodes or features being “connected” or “coupled” together. As used herein, unless expressly stated otherwise, “connected” means that one element/node/feature is directly joined to (or directly communicates with) another element, node or other feature in a mechanical, logical, electrical or other appropriate sense. Likewise, unless expressly stated otherwise, “coupled” means that one element/node/feature is directly or indirectly joined to (or directly or indirectly communicates with) another element/node/feature in a mechanical, logical, electrical or other appropriate sense. The term “exemplary” is used in the sense of “example,” rather than “model.” Further, although the figures may depict example arrangements of elements, additional intervening elements, devices, features, or components may be present in a practical embodiment of the invention.