Suspension height sensor

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

TECHNICAL FIELD

The present invention generally relates to vehicular suspension systems, and more particularly relates to a suspension height sensor integrated into a vehicular suspension system.

BACKGROUND OF THE INVENTION

Control systems that automatically regulate ride height have been integrated into the suspensions of many vehicles. These systems rely on height sensors to provide real-time feedback on the distance or relative height between selected suspension components of sprung and unsprung vehicle masses. These data may be relayed to controllers that respond to 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, acceleration, and braking.

Typical suspension height sensors use mechanical linkages connected between monitoring points in the suspension that convert linear displacement to a rotary motion. A contacting or non-contacting, electro-mechanical sensor converts this angular displacement to an electrical signal indicative of the relative height. 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 or degrade long term performance and reliability.

Accordingly, there is a need to provide a suspension height sensor for a vehicle that is simpler to assemble, more convenient to service, and reduces part count. Further, 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 first portion of a vehicular suspension assembly and a second portion of the suspension assembly. The system comprises a transceiver coupled to the first portion for emitting a first signal toward the second portion, and for receiving a reflection of the first signal from the second portion, and a processor coupled to the transceiver for determining the distance between the first portion and the second portion.

In accordance with another embodiment, by way of example only, a system is provided for determining a distance between a first portion of a vehicular suspension assembly and a second portion of the suspension assembly. The system comprises a transmitter coupled to a first portion for emitting a first signal, a receiver coupled to a second portion for detecting the first signal, and a processor coupled to the transmitter and the receiver, the processor configured to determine the distance between the first portion and the second portion.

In accordance with yet another embodiment, by way of example only, a system is provided for determining a distance of travel of an actuator assembly for a vehicular suspension assembly. The suspension assembly has a first member and a second member, and the actuator assembly has a first end coupled to the first member and a second end coupled to the second member. The system comprises a transceiver coupled to the first end for emitting a first signal, and for receiving a reflection of the first signal from the second end, a reflector coupled to the second end for reflecting the first signal, and a processor coupled to the transceiver for determining the distance of travel.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT

The various embodiments of the present invention described herein provide an electronic height sensing system or height sensor for a vehicular suspension that measures the distance or relative height between selected components such as, for example, between the sprung and unsprung vehicle masses. When coupled to a suitable accompanying processor, a quantified determination of relative height useful to a chassis control system is achieved. Such relative height information may be further used to determine the distance of travel of various types of suspension actuators, including but not limited to linear actuators. Electromagnetic or ultrasonic wave transmitters or transceivers coupled to a first suspension component emit signals toward either a receiver or a reflector coupled to a second suspension component that receives the source signal directly or reflects the source signal back to the transceiver. Such transmitting/receiving devices may send electronic signals in the form of, for example, timing pulses or digitized data, indicative of relative height to a coupled processor configured to use these signals in determining the actual relative height between components. Data relating to relative height may also be used to determine the relative velocity and acceleration between suspension points being monitored and, combined with distance of travel data, can be used by a chassis controller to better optimize responsive adjustments made to controlled suspension components. Further, system elements used for signal emission and detection may assume a wide variety of configurations and locations on a vehicle suspension to accommodate gathering data relating to chassis movements, and to be conveniently accessible for service when needed.

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)50. 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 portions of chassis12. Suspension assembly22may include springs, linear actuators, and other interconnecting and supporting members, and further includes at least one damper assembly24such as a shock absorber or a strut, or the like, for providing damped motion between sprung and unsprung vehicle masses. Damper assemblies24may be configured to respond passively to vehicle motion, or as shown inFIG. 1, may be coupled to CCM50and configured to provide actively controlled suspension adjustments as directed thereby. As shown, vehicle10has four such damper assemblies24coupled to suspension assembly22proximate to wheels16, and coupled in communication with CCM50.

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.

Chassis control module50is coupled in communication with various automotive sub-system sensors including a steering sensor30for determining steering direction, a lift/dive sensor34used to monitor chassis response to braking and accelerating, and a speed sensor38for measuring vehicle speed. CCM50also includes a user interface42whereby a driver may enter various system commands and receive therefrom other pertinent system information. CCM50is also coupled in communication with various vehicle height sensors56coupled to body14, chassis12, and/or suspension assembly22for monitoring vehicle height. CCM50also includes at least a processor60for processing vehicle height information received from height sensors56, and a controller70coupled to processor60for relaying electronic commands to controlled suspension components including, for example, damper assemblies24in response to processor prompts. During operation, height sensors56monitor the distance between selected suspension, body, and/or chassis components, and generate signals indicative of this distance to processor60. Processor60converts these signals to data that is useful to controller70in making appropriate compensating chassis adjustments.

FIG. 2illustrates selected components of height sensor56integrated into suspension assembly22in accordance with an exemplary embodiment. Suspension assembly22includes damper assembly24coupled between a sprung vehicle mass90and an unsprung vehicle mass96, and configured to dampen vertical motion therebetween in a well known manner. Damper assembly24has a first end coupled to a lower control arm140of unsprung mass96by a lower mount128, and a second end coupled to a frame structural member108of sprung mass90by an upper mount144. Mounting of damper assembly24to structural members and control arms may be done in any conventional manner using mounting brackets and fasteners. Height sensor56includes a transceiver112electrically coupled in communication with processor60(FIG. 1) and mechanically coupled to any suitable component of the sprung vehicle mass such as shown, for example, to frame structural member108. Height sensor56also includes a reflector116that may be coupled to any suitable component of the unsprung vehicle mass such as, for example, to lower control arm140. While sensing elements are illustrated as being positioned on suspension assembly22in accord with a specific configuration, it should be appreciated that many other possible configurations and suitable locations for mounting of these elements exist.

Transceiver112is configured to emit interrogation signals toward reflector116when prompted by processor60(FIG. 1), and to receive the interrogation signals reflected back from reflector116. The interrogation signals may be electromagnetic in nature including but not limited to ultra wide band (UWB) radar, infrared (IR), or laser light radiation, or may comprise an ultrasonic pressure (sound) wave. Reflector116may comprise any suitable surface reflective of the type of signal used. Depending on the type of signals used, transceiver112and reflector116may be positioned so as to have a substantially clear line-of-sight with each other to enable such signal transfer.

During operation, transceiver112and reflector116each move with the sprung and unsprung masses, respectively, and the distance therebetween dynamically changes in accordance with vehicle motion and road conditions. Transceiver112emits interrogation signals when prompted by processor60(FIG. 1) that reflect from the surface of reflector116back to transceiver112. Processor60records the time of prompting, and transceiver112detects the reflected interrogation signals, and relays an electronic signal to processor60indicative of the time of detection. Processor60is configured with algorithms for converting such timing information to the actual time differential between emission and detection, and for determining the distance or relative height differential between sprung and unsprung vehicle masses, H, using an algorithm that may include equation (1) below:
H=0.5c×[Δt](1)
where c is the speed of propagation of the emitted signal, and Δt is the time differential between emission and detection. In addition, the emitted signals may be pulsed having a duration and/or cadence optimized for use with the range of relative height range typical of a vehicle suspension system, and/or varied to encode the signal to enhance source recognition and mitigate the effects of stray light or other types of false signals.

Transceiver112is configured to both emit and detect signals and may comprise one of a variety of emission/detection systems based upon either electromagnetic radiation or sound waves. In one embodiment, transceiver112comprises 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 XS100. The detection component of transceiver112may be based upon RFCMOS (radio frequency, complementary metal oxide semiconductor) technology and is tuned to be compatible with the transmitter. In another embodiment, the transmitting component of transceiver112is a semiconductor-based laser diode that emits/detects light over a very narrow range of wavelengths. The detecting component may also be a semiconductor diode configured to detect light at the transmitted wavelength(s). In a further embodiment, transceiver112is configured to emit IR radiation and preferably comprises a semiconductor light emitting diode (LED). This type of device 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, transceiver112comprises an ultrasonic transducer configured to emit ultrasonic pressure waves coupled to another pressure transducer tuned to detect these sound waves. To aid in source recognition and mitigate the effects of stray radiation, each of the embodiments of transceiver112described above preferably emits a pulsed signal comprising short duration, electromagnetic or sound emissions.

Reflector116is configured to operate in conjunction with transceiver112, and thus is configured to reflect the type of signal emitted thereby. In the case wherein transceiver112emits UWB radiation, reflector116may be any surface that comprises a conduction band of free electrons such as any metallic surface. Reflectors for IR or laser sources may include materials such as polished stainless steel, aluminum alloys, or ceramics.

FIG. 3is a block diagram of selected components of CCM50from vehicle10(FIG. 1) including transceiver112, reflector116, processor60, and controller70in accordance with an exemplary embodiment. Processor60is operatively coupled to controller70, and is coupled in two-way communication with transceiver112. Transceiver112is configured to emit electromagnetic or ultrasonic interrogation signals toward reflector116when prompted by a signal, Sp1, from processor60, and to detect the reflection of these interrogation signals reflected from reflector116. Processor60records the time of prompting and transceiver112relays electronic timing signals indicative of detection timing (td) to processor60. In an alternate embodiment, transceiver112may send electronic signals to processor60indicative of the timing of both emission and detection. Processor60uses this timing information in conjunction with an appropriate algorithm previously described to determine the distance or relative height between transceiver112and reflector116. Controller70receives the height data as an input signal from processor60, and dispatches real-time commands to controlled suspension elements in response to current chassis conditions as reflected by this data.

FIG. 4is a cross-sectional view of damper assembly24comprising a height sensor120in accordance with an exemplary embodiment. Damper assembly24includes a damper tube assembly160, a cylindrical exterior housing or dust tube188, a piston rod148, an end portion196, an upper mount assembly180, and a lower mounting bracket168. Damper assembly24is connected in a conventional manner to lower control arm140(FIG. 2) at a first end200via mounting bracket168having an opening171configured to be used in conjunction with a suitable fastener. Damper assembly24is conventionally connected at a second end204to frame structural member108by a self-locking flange nut150that fastens to a threaded end154of piston rod148. Damper tube assembly160is connected to mounting bracket168(and thus to the unsprung vehicle mass) at a lower end202, and is connected to end portion196at an upper end206. Piston rod148is slidably coupled to and substantially concentric with damper tube assembly160and end portion196. An optional jounce bumper172comprised of a hard rubber or any suitable elastomeric material is disposed substantially concentrically about piston rod148, and is seated in a jounce bumper bracket178coupled to upper mount assembly180. In the case wherein a jounce bumper is present, end portion196is a jounce bumper stopper, and if not present, end portion196is an end cap. Dust tube188is coupled to upper mount assembly180(and thus to the sprung vehicle mass), and is substantially concentric with and slidably coupled to damper tube assembly160, and forms an outer housing for an upper portion of damper assembly24.

In one embodiment, height sensor120comprises a transceiver164coupled to jounce bumper bracket178(sprung vehicle mass), and a reflector170coupled to end portion196(unsprung vehicle mass). Reflector170may comprise a separate component coupled to end portion196, or may replace end portion196. Transceiver164and reflector170may comprise any compatible combination of signal type and reflector previously described. Processor60is coupled to controller70and is coupled in two-way communication with transceiver164. Processor60and/or controller70may be integrated within damper assembly24at any suitable location, or may be remotely located such as within CCM50(FIG. 1). The location of transceiver164and reflector170may be varied within damper assembly24provided one component is coupled to each vehicle mass and a sufficient line-of-sight between components, if needed, exists. For example, transceiver164may be coupled to dust tube188or upper mount assembly180, and reflector170may be mounted to end portion196(as shown). In another embodiment (not shown), the positions of transceiver164and reflector170are reversed. That is, transceiver164is coupled to the unsprung mass and reflector170is coupled to the sprung mass, each attached to any of the suitable locations within damper assembly24described above. Accordingly, at least a portion of jounce bumper172may be removed as needed to accommodate the final position of transceiver164and reflector170and the need for line-of-sight between these components.

During operation, the vertical distance between sprung and unsprung vehicle masses changes dynamically depending on road conditions and vehicle speed, causing damper tube assembly160to move along piston rod148into and out of dust tube188, changing accordingly the distance between transceiver164and reflector170. Processor60prompts transceiver164to emit pulsed interrogation signals toward reflector170that are then reflected back to transceiver164. Processor60records the time of prompting and transceiver164relays an electronic timing signal indicative of the timing of detection to processor60which is configured to determine the distance based on the time differential using an algorithm that may include equation (1) above.

FIG. 5illustrates another height sensor250integrated into suspension assembly22in accordance with another exemplary embodiment. Suspension assembly22has a damper assembly245coupled between sprung mass90and unsprung mass96in a manner previously described for damper assembly24(FIG. 2). Height sensor250includes a transmitter254coupled in two-way communication to processor60of CCM50(FIG. 1). Transmitter254is mounted to a suitable component of sprung vehicle mass90such as frame structural member108. Receiver258also communicates with processor60and is mounted to a component of unsprung vehicle mass96such as lower control arm140. Transmitter254is configured to emit pulsed UWB, IR, laser, or ultrasound interrogation signals directed toward receiver258when prompted by a signal, Sp1, from processor60, and may comprise any of the types of transmitters previously described. Receiver258is configured to detect signals from transmitter254and comprises a compatible detector of the types described above. Processor60records the time of prompting, and receiver258relays an electronic signal, td1, indicative of detection timing to processor60. Processor60is configured with algorithms for converting such timing information to the actual time differential between emission and detection, and for determining the distance or relative height between sprung and unsprung vehicle masses, H, therefrom in accordance with equation (2):
H=c×[Δt](2)
wherein c is the speed of propagation of the signal, and Δt is the time differential. In another embodiment, the positions of transmitter254and receiver258are reversed and transmitter254is coupled to a suitable component of the unsprung mass96, and receiver258is coupled to a suitable component of the sprung mass90. In a similar manner, transmitter254emits a pulsed signal that is detected by receiver258. Timing signals are transferred to processor60wherein the time differential between emission and detection and the concomitant distance or relative height are similarly determined.

FIG. 6is a block diagram of selected components of CCM50from vehicle10(FIG. 1) including transmitter254, receiver258, processor60, and controller70in accordance with an exemplary embodiment. Processor60is operatively coupled to controller70, and also communicates with transmitter254. Processor60sends a prompting signal, Sp1, to transmitter254which is configured to emit electromagnetic or ultrasonic interrogation signals toward receiver258when prompted. Preferably, processor60records the time of prompting or, alternatively, transmitter254sends an electronic signal to processor60indicative of the time of emission. Receiver258detects the interrogation signal from transmitter254and sends a timing signal, td1, indicative of the timing of signal detection to processor60. Processor60uses this timing information in conjunction with an appropriate algorithm that may include equation (2) above to determine the distance or relative height between transmitter254and receiver258. Controller70receives this relative height data as an input signal from processor60, and dispatches real-time commands to controlled suspension elements in response to current chassis conditions.

FIG. 7illustrates damper assembly245having an integrated height sensor265in accordance with yet another embodiment. Damper assembly245has many of the same mounting and internal components that have been previously described for damper assembly24(FIG. 2) and so, in the interest of brevity, these details will not be repeated. Height sensor265comprises a transmitter264coupled to a suitable location within damper assembly245such as, for example, to upper mount assembly290(sprung vehicle mass), and a receiver272coupled to an end portion296(unsprung vehicle mass). In the case where a jounce bumper is used (not shown) transmitter264may have a suitable housing to protect it. Processor60is operatively coupled to controller70, and may send and/or receive electronic signals from transmitter264, and may receive signals from receiver272. Processor60sends prompting signals, Sp1, to transmitter264to emit interrogation signals directed toward receiver272, and preferably records the time of prompting or, alternatively, receives timing signals from transmitter264indicative of emission timing. Receiver272detects these interrogation signals and transmits a timing signal, td1, to processor60indicative of the timing of signal detection. Processor60uses such timing information to generate data related to relative vehicle height in a manner described previously. This data may be sent to controller70configured to dispatch signals to selected controlled suspension members, that may include damper assembly245, to make responsive chassis adjustments.

Relative height data generated by height sensors having either a transceiver/reflector or a transmitter/receiver configuration may also be used to determine the relative velocity and relative acceleration between suspension components. An average relative velocity, Va, between two times, t1and t2, may be determined using the instantaneous relative heights, Hi1and Hi2at t1and t2, respectively, using an appropriate algorithm that may include equation (3):

Instantaneous relative velocity, Vi, may also be determined using an appropriate algorithm that may include equation (4):

Data relating to instantaneous relative velocity may be similarly used to determine an average relative acceleration, Aa, using an appropriate algorithm that may include equation (5):

Aa=(Vi⁢⁢2-Vi⁢⁢1)(t2-t1)(5)
wherein Vi2is the instantaneous velocity at time t2, and Vi1is the instantaneous velocity at time t1. Instantaneous acceleration Aimay then be determined using an appropriate algorithm that may include equation (6):

FIG. 8illustrates a suspension actuator300having a height sensor304for measuring the distance of travel of actuator300in accordance with another exemplary embodiment. Suspension actuator300may be, for example, a passive damper assembly including a shock absorber or a strut, or an actively controlled actuator such as a linear actuator. In the example depicted inFIG. 8, suspension actuator300is a linear actuator having a first portion328coupled to a first suspension member308and a second portion332coupled to a second suspension member312. First portion328is fixed relative to second portion332which moves in and out of first portion328in a well known manner in response to vehicle motion and/or controller commands. The distance of travel is defined as the amount of linear travel of second portion332with respect to a reference/zero position such as where second portion332is fully retracted within first portion328. Distance of travel is thus the difference between the relative height determined at the position of interest and the relative height determined at the reference position.

Height sensor304includes a transceiver316coupled to second portion332and a reflector324coupled to first portion328. These components may be any compatible combination of transceiver/reflector of the types previously described. Transceiver316is coupled in two-way communication with processor60and is configured to emit interrogation signals directed toward reflector324when prompted by a signal, Sp1from processor60, and to receive a reflection of the interrogation signals from reflector324. Processor60records the time of prompting, and transceiver316sends an electronic signal, td1, indicative of detection timing to processor60. Processor60is configured with algorithms described above for determining the relative height or distance between transceiver316and reflector324. The distance of travel, DT, at a time t1may be determined using algorithms that may include equation (7) below:
DT=Ht1−HR(7)
wherein HRis the relative height determined at the reference position, and Ht1is the relative height determined at time t1.

FIG. 9illustrates suspension actuator300having a height sensor340for measuring the distance of travel of actuator300in accordance with yet another exemplary embodiment. Height sensor340includes a transmitter344coupled to second portion332and a receiver348coupled to first portion328. Processor60sends prompting signals, Sp1, to transmitter344to emit interrogation signals toward receiver348, and records the time of prompting. Receiver348detects the interrogation signals and sends timing signals, td1, to processor60indicative of the timing of detection. Processor60determines the distance of travel of actuator300at a specified time using algorithms that may include equation (7) above.

The embodiments described herein provide a height sensor for determining the distance or relative height between components of a vehicular suspension. Processor-controlled systems use pulsed electromagnetic or ultrasonic pressure wave interrogation signals emitted and detected using either transceiver/reflector or transmitter/receiver configurations. Electronic timing signals indicative of emission and detection timing are sent to a processor configured to determine the time differentials and the corresponding relative height. Relative height data generated over a time interval may be used to determine both relative velocity and relative acceleration between suspension members for that interval. Further, relative height may be used to determine the distance of travel of a passive or actively controlled suspension actuator at a specific time. Such data relating to component relative height, distance of travel, velocity, and/or acceleration may be relayed to a suspension processor/controller to provide real time chassis suspension control to enhance driving stability and handling performance.

The preceding detailed description is merely illustrative in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary, or detailed description. The invention may be described herein in terms of functional and/or logical block components and various processing steps. It should be appreciated that such block components may be realized by any number of hardware, software, and/or firmware components configured to perform the specified functions.

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.