Patent Application
20190359025
This disclosure relates to suspension control systems and methods for vehicles. In particular, the disclosure relates to active suspension control systems and methods for adapting the suspension of a vehicle in response to off-road or no-road conditions.
In both industry and leisure applications, it is often desirable to traverse rough terrain in a wheeled vehicle, such as a truck or in other forms of utility vehicles, for the purpose of reaching often remote destinations. For example, in the electrical powerline industry, conducting repair work on transmission lines may require transporting personnel and equipment to a remote mountain location that is not accessible by cleared roads. Other challenging terrain may include muddy conditions which present traction problems for a wheeled vehicle. In recreational and sport applications, off-road racing events often require participants to traverse rough terrain at higher speeds.
Conventional vehicle suspension systems are typically not capable of traversing such terrain, as climbing the vehicle over large obstacles such as fallen trees or boulders, combined with the uneven nature of the ground itself including ruts and ditches, while travelling either up, down or transversely across a slope, often causes each of the four wheels to be positioned at varying heights which may cause one or more wheels to lose contact with the ground, thereby often causing the vehicle to become immobilized, necessitating winching or the like to free the vehicle. Further problems are presented, for example, by travelling up or down slopes of 40° or greater, as modern suspension systems do not sufficiently adapt to compensate for the shifting center of gravity of a vehicle traversing such slopes, which may cause the vehicle to roll to the side or flip over the front or rear ends of the vehicle.
At present, for industrial applications requiring transport of personnel and equipment over rough terrain, businesses may utilize a vehicle having tracks instead of wheels to traverse the rough terrain; however, the disadvantage of using such vehicles is that they move slowly relative to wheeled vehicles, typically reaching top speeds of only 5 to 10 mph under such terrain conditions. As well, most track vehicles are unable to traverse steep slopes due to the weight of the vehicle not being evenly distributed across the tracks and the difficulty in gaining traction under such conditions, as well as the tendency of mud, rocks and other debris becoming entrapped within the track mechanism. Another option, either alone or in combination with tracked vehicles or regular trucks, is to use one or more All-Terrain Vehicles (ATVs) in order to transport personnel and equipment from a larger vehicle to the remote work site over the difficult terrain that cannot be traversed using the larger vehicle; however, this is a time-consuming process that may require several trips to complete, depending on the amount of equipment and personnel to be transported.
To the Applicant's knowledge, there are certain innovations existing in the prior art for actively controlling the suspension system of wheeled vehicles; however, these systems are typically directed to improving the comfort or performance of vehicles under typical driving conditions traversing a road. For example, the car manufacturer Mercedes-Benz™ markets an active suspension control system under the name Active Body Control™ (ABC), in which the suspension assembly includes a coil spring and damper connected in parallel, along with an hydraulic adjusting cylinder, whereby the adjusting cylinder is used to adjust the length of the suspension assembly. The adjusting cylinder is controlled by an electronic controller which receives input from various sensors on the vehicle and accordingly adjusts the length of the suspension assembly by controlling the hydraulic actuator. However, the ABC system, in Applicant's view, is complex, expensive and relatively heavy due to the use of powerful magnets. Furthermore, to the Applicant's knowledge, the ABC system has not been advertised for use in the rough terrain conditions described above.
Other road vehicles known to the Applicant offer various pre-set modes for tuning the suspension of the system, the pre-set modes being selected by the user for a given terrain. Such suspension systems may, to Applicant's knowledge, typically utilize a coil spring suspension combined with a hydraulic or pneumatically operated damper. In some systems, the damper component may contain a magnetorheological fluid which is capable of being adjusted for viscosity, thereby adjusting the stiffness of the damper, by applying or varying an electromagnetic field. However, again to the Applicant's knowledge, such systems only offer a finite number of suspension system settings and are typically not capable of dynamically adjusting components of the suspension system in response to changing terrain or driving conditions. For example, such systems may only include the ability to adjust the stiffness of the damper but not the spring, as a coil spring does not readily provide for adjustability. Other suspension systems may include the ability to adjust components of the suspension system in response to certain terrain conditions as detected by sensors on the vehicle, typically the damper; however, such systems are typically only capable of adjusting the suspension to one of a finite number of operating modes, which would in Applicant's view not be effective for crossing particularly rough terrain presenting large and unexpected obstacles, such as fallen trees or boulders.
Another active suspension system of which the Applicant is aware includes a system developed by Bose™ which utilizes electromagnetic struts to extend or retract each wheel independently of the other wheels. Although the Bose™ electromagnetic active suspension system was publicly revealed as early as 2004, to the knowledge of the Applicant this system has not been made commercially available due to the high cost of implementing such a system in a vehicle.
Thus, there exists a need for a cost-effective, lighter weight and otherwise improved active suspension control system and method for a wheeled vehicle that provides continuously variable adjustment of the components of the suspension system in response to detected changes in the terrain conditions, where the system is capable of enabling the vehicle to cross even rough terrain conditions.
In one aspect of the present disclosure, an active suspension control system and method is described which provides for individual, automatic adjustment of an adjustable suspension air spring for each wheel of a vehicle for a given terrain. Ideally, each spring may be substantially infinitely adjustable between the operational travel limits of each component, thereby improving the ability of the system to respond to and handle difficult obstacles and driving conditions that may be encountered by a no-road vehicle.
In one aspect of the present disclosure, the suspension assembly of each wheel is independently adjustable and consists of an adjustable suspension spring having at least two chambers, alternatively referred to herein as upper or “A” chambers and lower or “B” chambers, and an inlet/outlet valve for each chamber, whereby the pressure in either or both of the upper and lower chambers may be individually and independently adjusted by an electronically controlled valve block or other valve arrangement cooperating with an on-board processor. Advantageously, such a dual-chamber adjustable suspension air spring controlled by the processor in response to sensor inputs or user-selected pre-set operating modes enables both ride height adjustment of each individual wheel, as well as providing for forced (as opposed to passive) extension or retraction of the spring and/or adjusting the stiffness of the adjustable suspension air spring so as to adjust the spring rate. Although the adjustable, dual-chamber suspension air spring is generally described herein as using air for the operating gas, it will be appreciated by a person skilled in the art that the present disclosure is not so limited and that other gases or fluids may be utilized as the operating gas or fluid to independently change the pressure in the chambers of the adjustable suspension spring. For example, compressed CO2 or other suitable compressed gases, or as another example, hydraulic fluids used in conjunction with air or another compressible gas or compressible fluid to change the pressure of the compressible gas or fluid, may also be employed.
In another aspect of the present disclosure, a method for automating the control of the active suspension system is provided. By utilizing various different sensors to determine the operating condition of the vehicle and/or the condition of the surrounding terrain at a given point in time, for example sensors monitoring the position of the suspension system or wheel relative to the frame or chassis, and pressure sensors in each of the upper and lower chambers of each air spring, an electronic controller and cooperating processor controls the valving of each inlet/outlet or port of each chamber of each air spring so as to independently adjust the pressure in the upper and lower chambers of each cylinder suitable for a given terrain condition detected by the sensors, as determined by the processor.
In another aspect of the present disclosure, an active suspension control system for individually controlling a suspension assembly of each corresponding wheel assembly of a plurality of wheels of a vehicle in response to driving conditions, the control system comprising a plurality of suspension assemblies corresponding to the plurality of wheels, each suspension assembly of the plurality of suspension assemblies including an adjustable suspension spring, each adjustable suspension spring of the plurality of suspension assemblies including a hollow, fluidically sealed cylinder and a piston having a shaft and a head, the piston cooperating within the cylinder, the cylinder having an upper chamber divided from a lower chamber by the piston head, the lower chamber being adjacent to the piston shaft coupled to the corresponding wheel assembly, each chamber of the upper and lower chambers of the suspension spring having a port fluidly coupled to a fluid line and a valve of a valve assembly, wherein a first end of the fluid line is fluidly coupled to the port and a second end of the fluid line is coupled to the valve, the valve assembly operatively coupled to an electronic controller to control each valve of the valve assembly and a fluid source fluidly coupled to each valve of the valve assembly, wherein the extension or retraction of each adjustable suspension spring is controlled by selectively introducing and/or removing a volume of a fluid from the upper and/or lower chambers of said adjustable suspension spring through the fluid line.
In still another aspect of the present disclosure, a method of controlling an active suspension system of a vehicle having a plurality of wheels, the active suspension system including a suspension assembly corresponding to each wheel assembly of each wheel of the plurality of wheels, the method steps comprising: providing a suspension assembly corresponding to each wheel assembly, each suspension assembly including an adjustable suspension spring having a hollow, fluidically sealed cylinder and a piston having a shaft and a head, the piston cooperating within the cylinder, the cylinder having an upper chamber divided from a lower chamber by a piston head, the lower chamber being adjacent to the piston shaft coupled to the corresponding wheel assembly, each chamber of the upper and lower chambers of the suspension spring having a port selectively fluidly coupled to a fluid supply through a fluid line and a valve of a valve assembly, the valve assembly operatively coupled to an electronic controller to control each valve of the valve assembly, receiving one or more control inputs into the electronic controller, generating one or more control outputs, each control output of the one or more control outputs including an instruction to one or more valves of the valve assembly to open or close so as to add a fluid of the fluid supply to or remove the fluid from the upper or lower chamber of one or more adjustable suspension springs, and applying the one or more control outputs by the electronic controller to the one or more valves of the valve assembly.
In accordance with the present disclosure, the active suspension system 10 comprises a valve assembly 12, such as a valve block, operatively connected to a fluid source 14 and an electronic controller 16. The valve assembly 12 may comprise a plurality of bidirectional valves, wherein each bidirectional valve is connected to a fluid line leading to either the upper chamber or the lower chamber of an adjustable suspension spring. As used herein, a fluid line and fluid source refer, in describing an embodiment of the present disclosure, to an air line and an air source, respectively; however, it will be appreciated by a person skilled in the art that other compressible gases or other fluids may also be utilized and fall within the scope of the present disclosure.
As shown in
Each adjustable suspension spring is divided into two chambers. For example, the front left adjustable suspension spring 20 is divided into an upper chamber 20a and a lower chamber 20b, whereby the upper and lower chambers 20a, 20b, are separated by the piston 26. Piston shaft 27 extends through the lower chamber 20b and is adjacent wheel assembly coupling 28. As used herein and in the accompanying drawings, the terms “upper chamber” and “A chamber” are used interchangeably, and the terms “lower chamber” and “B chamber” are used interchangeably. Thus, when a wheel assembly coupled to an adjustable suspension spring encounters a rock, log or other obstacle on the terrain over which the vehicle is travelling, the approximately vertical force of the force vector experienced by the wheel is transmitted through the coupling 28 and shaft 27 to slide the piston 26, thereby increasing the pressure in upper or A chamber (20a, for example) and decreasing the pressure in the lower or B chamber (20b, for example), presuming that the operating fluids in the upper and lower chambers are compressible.
Similarly, adjustable suspension spring 22 is divided into upper and lower chambers 22a, 22b; adjustable suspension spring 30 is divided into upper and lower chambers 30a, 30b; and adjustable suspension spring 32 is divided into upper and lower chambers 32a, 32b. Each of the upper and lower chambers 20a, 20b of the adjustable suspension spring 20 are provided with a port 25 fluidly coupled to a fluid line 23, and each fluid line 23 is attached at the other end to a valve 21 mounted to the valve assembly 12. Similarly, the upper and lower chambers of each of the other adjustable suspension springs 22, 30, 32, each are provided with an port 25 coupled to a fluid line 23, whereby the opposite end of the fluid line 23 is coupled to a valve 21 mounted to the valve assembly 12. Furthermore, each of the upper and lower chambers of each of the adjustable suspension springs 20, 22, 30, 32, are provided with a pressure sensor 29 for monitoring the pressure of each chamber. The pressure sensors 29 are in electronic communication with electronic controller 16; however, wires between the sensors 29 and the electronic controller 16 are not illustrated in the Figures for the sake of clarity. In other embodiments of the present disclosure, the electronic communication between the electronic controller 16 and the sensors may also be accomplished wirelessly.
Thus, it may be appreciated that in the embodiment of the active suspension system 10 illustrated in
It will be appreciated by a person skilled in the art that the spring rate and other characteristics, such as actively and positively extending or retracting the positioning of the rods of the adjustable suspension springs 20, 22, 30, and 32, may thus be adjusted by actively adding air to or by actively removing air from the upper and/or lower chambers through the fluid lines 23, and controlled by the valves 21 mounted to the valve block or valve assembly 12. The fluid source 14 provides the working compressible fluid being used to adjust pressures in each of the upper and lower chambers of the adjustable suspension springs. So for example, in a pneumatic suspension system, each of the adjustable springs may be air springs and the working fluid being added to or removed from adjustable suspension spring upper and lower chambers is compressed air obtained from fluid source 14, which may for example be a conventional air compressor. However, it will be appreciated by a person skilled in the art that other adjustable suspension springs systems utilizing different fluids to control the pressure in the upper and lower chambers of the adjustable suspension springs may also be utilized and are intended to included within the scope of the present disclosure. For example, the fluid provided by the fluid source 14 may include compressed gases other than air, such as for example carbon dioxide or other suitable inert compressible gases known to a person skilled in the art, or may include for example hydraulically driven systems wherein the fluid source 14 provides hydraulic fluid or other non-compressible fluid so as to compress or de-compress the air or other compressible gas within that particular chamber by adding or removing fluid to the chamber.
In an alternative embodiment of the present disclosure, as illustrated in
Now referring to
Below, the Applicant describes several different control states and control functions or methods that may be implemented using the active suspension system 10 disclosed herein. As will be appreciated by a person skilled in the art, in some cases, some of the control functions described below may be designed to work in parallel with other control functions, while in other cases, a particular control function may be intended to work alone or in combination with only certain other control functions. For each of the control functions described below, the electronic controller 16 automatically implements the particular control function for a particular mode or state of operation, depending on inputs received from various sensors deployed throughout the vehicle 1 and/or instructions input to the electronic controller 16 by the user of the system.
Referring now to
Without intending to be limiting, the relationship between the various control functions which control operation of the active suspension system 10 may be described based on the various states of the suspension system 10 and how those states may relate to each other. Without intending to be limiting, the applicant refers to the state diagram of
With reference to
As another example, again without intending to be limiting, for a four wheel drive (4WD) vehicle, the pre-set suspension settings available when the system 10 is in the selected suspension setting state 110 may include separate settings for low range and high range. A pre-set suspension setting for high range 4WD may increase the ride height to the range of 45-50% of the total possible ride height, and for low range 4WD at medium speeds, the ride height may be increased to the range of 65-70% (when medium clearance conditions are presented), and yet another pre-set suspension setting for high range 4WD adjusting the ride height to the range of 85-90% (for low speed conditions when high clearance conditions, for example large obstacles such as fallen logs and boulders, are presented). Still another pre-set suspension setting for low range 4WD vehicle mode may be available for driving conditions that include for example crossing over ditches or drop offs at a high speed, such as may be required in recreational off road vehicle competitions, in which each of the adjustable suspension springs are set at approximately 90% of the total possible ride height, and in addition, the rear lower or B chambers 30b, 32b are each pressurized so as to pull down the ride height of the adjustable rear suspension springs 30, 32 to approximately 80% of the total available ride height. The phrase “pull down the ride height” is defined by reducing the angle A between the A-arm and the plane of the bumper (as seen in
Once the suspension system 10 is in the selected suspension setting state 110, the control may return to the neutral suspension state 100, for example when the user powers the control system on. Otherwise, once the suspension system 10 is in selected suspension state 110, the system may move to any given number of states either as a result of changes in terrain or driving conditions that are automatically detected by sensors cooperating with the system 10, or otherwise as a result of instructions input into the system 10 by the user. Each of the states may represent a different control functionality carried out by the system. For example, if the vehicle 1 begins to travel over very uneven terrain, causing the vehicle 1 to become very unlevel, sensors positioned throughout the vehicle indicating that the vehicle 1 is oriented in such a manner so as to cross a given threshold angle α (illustrated in
Other examples of various different states that the suspension system 10 may enter into include a reversing and stability state 140, in which state the suspension system 10 would adjust the suspension in accordance with an algorithm so as to increase the stability of the vehicle 1; an example of a reversing and stability control algorithm is provided in
Another control function which may assist with preventing a vehicle 1 from flipping end-over-end when travelling at a high velocity and encountering a ditch or drop off; for example, the pitch control state 150, wherein the rear suspension is pulled down relative to the front suspension (ie: angle A reduced on both sides), as will be described further below. The pitch control state 150 may be a user selected suspension setting. In some embodiments of the present disclosure, such as is shown in
Other control states that may form part of the suspension system 10 includes a cornering assist state 160, which may be triggered for example upon automated detection of the steering column having rotated beyond a predetermined threshold angle, or any other suitable means for detecting when a vehicle 1 is entering into a turn such that the cornering assist state 160 should be engaged. The control system may also include sway bar state 170, which, as will be described below, involves adjustments to the suspension springs 20, 22, 30, and 32 so as to restrict body roll and provide similar functionality to having a mechanical sway bar, which sway bar state 170 may advantageously be turned selectively on and off. Crossover state 180 may allow crossflow of the fluid or gas between adjacent upper chambers so as to balance the pressure between those two upper chambers, for example between chambers 20a and 22a through crossover line 43 by opening crossover valve 41.
An example of an algorithm that may be utilized to achieve leveling of vehicle 1 in the leveling state 120 will now be described with reference to
Upon polling a bi-directional level sensor in step 200, step 202 would query whether the pitch and roll of the vehicle 1, as measured by the level sensor, falls within certain threshold levelling limits of the system 10. In the case that the vehicle 1 is level within the threshold limit, the algorithm may return to step 200 of continuing to poll the bi-directional level sensors, for example at a frequency of once per second or any other polling rate that would be suitable for a particular application. In the event that the level, or in other words the pitch and roll of the vehicle 1, fall outside of the threshold limit, the algorithm would proceed to step 204 at which step the suspension system 10 determines whether the level sensor indicator has detected an imbalance in either the pitch or roll the vehicle, or both. For example, if, such as seen diagrammatically in
By way of example, without intending to be limiting, if from the driver's perspective the sensor indicator is in the front left quadrant of the inclinometer, this means the rear right wheel 2 of vehicle 1 is too low relative to the other three wheels, and therefore the suspension spring 32 corresponding to the rear right wheel requires pressure to be added to the A chamber 32a so as to raise the right rear wheel relative to the other wheels. If it is not possible to add pressure to the A chamber 32a, then it may be possible to reduce the pressure in the A chamber 20a of the suspension spring 20 corresponding to the left front wheel of the vehicle to thereby lower the left front wheel relative to the other three wheels. This type of correction is what is meant in the description of the algorithm steps of
Continuing the description of the levelling algorithm of
Returning to step 204 in the algorithm described in
In the event that the sensor indicator is located on the z-axis on indicating an imbalance in the pitch of the vehicle, at step 214 of the algorithm it may be determined whether the sensor indicator is located on the front or rear portion of the z-axis. For example, should be sensor indicator be on the front portion of the z-axis, then the algorithm in step 216 may determine whether the pressure of the two rear suspension spring A chambers 30a, 32a may be increased so as to raise the rear axle of the vehicle 1 relative to the front axle. If such a pressure increase in the rear upper or A chambers of the adjustable suspension springs is possible, then in step 218 the system 10 may cause the pressure of the upper chambers 30a, 32a, to increase and thereby raise the rear axle of the vehicle, after which point the algorithm would again return to step 200. However, in the event that the pressure of the two rear spring A chambers 30a, 32a are not capable of being increased, for example because the two rear A chambers 30a, 32a are already pressurized by the maximum amount, then the algorithm would move to step 220 to decrease the pressure in the two front spring suspension A chambers 20a, 22a, so as to lower the front axle of the vehicle relative to the rear axle, after which the algorithm would return step 200.
Similarly, at step 222, should the sensor indicator be located on the rear portion of the z-axis, the algorithm would determine whether the pressure of the A chambers 20a, 22a of the two front suspension springs 20, 22, may be increased, and if so, the pressure of the A chambers 20a, 22a are accordingly increased at step 224. On the other hand, should the upper or A chambers 20a, 22a not be capable of further pressure increases, in step 226 the pressure of the upper or A chambers of the two rear suspension springs 30a, 32a would be decreased, thereby lowering the rear axle of the vehicle 1 relative to the front axle. Again, after either step 224 or step 226 had taken place, the algorithm would return to step 200 to poll the level sensors to determine the new orientation of the vehicle after the suspension adjustments have been made. The algorithm described in
It will be appreciated by a person skilled in the art that the leveling function algorithm presented in
In some embodiments of the present disclosure, as described with reference to
As shown for example in
In the pressure balancing state 130, the algorithm may commence with step 306 wherein the pressure sensors 29 in each of the upper chambers 20a, 22a, 30a, and 32a may be queried so as to determine whether the pressure balance amongst the four tires is substantially equal within a pressure balance threshold, as determined in step 308. The object in state 130 is to adjust the pressure in the A and B chambers of each cylinder 22 so that each tire exerts the same downward pressure on the ground G or obstacle O. Where the downward pressure exerted by each of the four tires falls within a given threshold, the algorithm may return to polling the level sensor at step 300 so as to determine whether leveling adjustments are required, as more fully described above with reference to
The reversing and stability state 140, shown in
As shown in
Once the uphill B chambers have been pressurized so as to meet the requirements of step 406 (in the illustrated example, an angle change in the range of 15 to 20°), at step 408 fluid is added to the downhill A chambers so as to fully extend those suspension springs, for example by pressurizing the A chambers of the downhill suspension springs in the range of approximately 200 psi. The incremental pressurization of the uphill B chambers (in step 404) accomplishes stiffening the corresponding uphill suspension springs, while fully pressurizing the downhill A chambers in step 408 accomplishes extending those suspension springs to their fullest amount of travel distance D, which thereby accomplishes leveling out the vehicle 1 to come within a certain levelling threshold, even when the vehicle itself is on a slope of 15° or more.
Once the pressure adjustments have been made to the downhill A chambers in step 408, at step 410 the angle sensors are again queried or polled and in step 412 the system determines whether the measured angles indicate that the vehicle has been sufficiently stabilized for traversing a slope, or otherwise whether the orientation of the vehicle meets a second threshold angle, thereby indicating that further adjustments are required to complete the stabilization process. In the case that the vehicle's orientation exceeds a second threshold angle at step 412, thereby indicating that the vehicle is not yet been stabilized, at step 414 the uphill A chambers may be depressurized and the uphill B chambers may be further pressurized, for example by substantially 20 to 40 psi, at the same time, thereby further stiffening the uphill suspension springs while at the same time lowering the uphill suspension springs so as to accomplish further leveling and stabilization of the vehicle 1 while on slope. In the event that, at step 412, it is determined that the second threshold angle is not met, thereby indicating that the vehicle is stable within acceptable threshold, then only the uphill A chambers are depressurized in step 416, thereby lowering the uphill suspension springs so as to further level vehicle but without stiffening the uphill suspension springs any further. In either case, after either step 414 or step 416 has taken place, the algorithm returns to step 400 is to once again poll the angle sensors and determine whether the reversing and stability state 140 is still required. As shown in
The pitch control function may be useful for when the vehicle 1 is travelling quickly over terrain with sudden holes or cross ditches that may cause the front end of the vehicle 1 to dive downwardly and then the rear of the vehicle to kick upwardly, which may cause the vehicle to flip over its front end. When the system 10 is in the pitch control state 150, the suspension system is adjusted so as to help prevent the vehicle from flipping over its front end, by increasing the pressure in the front A chambers 20a, 22a thereby transferring weight toward the rear of the vehicle 1 and also minimizing the compression of the front springs 20, 22. At the same time, air or other fluid is added to the B chambers 30b, 32b of the rear springs 30, 32, which pulls down the rear of the vehicle and further assists in transferring weight toward the rear end of the vehicle 1.
Regarding the cornering assist state 160, illustrated in
At step 502, the algorithm may query whether the detected steering angle exceeds a given threshold angle which indicates that the vehicle entering into a turn. The threshold angle may be selected so as to control how sensitive the system 10 will be to changing directions of the vehicle, thereby triggering the system 10 to enter the cornering assist state 160; for example, a smaller threshold steering angle would ensure the state 160 is triggered when the vehicle makes slight changes in direction, whereas a larger threshold steering angle may be selected so as to only trigger the steering assist function when the vehicle is entering into a large turn. The polling of the steering sensor that occurs in step 500 may optionally include, in some embodiments of the present disclosure, polling the speedometer of the vehicle so as to adjust the triggering of the steering assist function by taking both the speed and the change of direction of the vehicle's travel into account. For example, at normal highway speeds, setting the threshold steering angle at lower limits as the trigger for entering the steering assist control function may be desirable because smaller adjustments to the steering angle at higher speeds will result in greater changes in direction. Furthermore, a higher speed of travel of the vehicle may require a greater adjustment to the suspension springs as a result of a greater centripetal force acting on the vehicle.
The applicant has found, in respect of the cornering assist functionality, that when a vehicle is entering into a turn, increasing the pressure of the rear inside corner B chambers of the suspension springs correlating to the rear inside corner wheel 2 of the vehicle 1 will have the effect of stiffening the suspension and increasing the spring rate of that suspension spring, thereby stabilizing the vehicle during the turn. By making such adjustments to the suspension spring, the applicant has found that the vehicle effectively leans into the corner, having an effect on the stability of the vehicle similar to banking the curve through which the vehicle is travelling. Optionally, in order to further cause the vehicle 1 to lean into the turn, increasing the pressure of the front outside A chamber of the adjustable suspension spring correlating to front outside corner wheel 2 of the vehicle 1 may further stabilize the vehicle by essentially extending the suspension spring on the front outside corner of the vehicle during the turn, thereby causing the vehicle to lean further into the curve. Although the optional adjustment of increasing the pressure of the front outside a chamber of the correlating suspension spring furthers the stability of the vehicle 1 during the turn, the applicant has found that this optional adjustment is not necessary and that the turn assist function may be adequately implemented by only increasing the pressure of the rear inside B chamber of the suspension spring correlating to the rear inside corner wheel of the vehicle.
Thus, once step 502 with the algorithm has determined that the steering angle exceeds the threshold indicating that the vehicle is entering a turn, the algorithm proceeds to step 504 where the speedometer and the steering sensor may again be polled to determine the speed and sharpness of the turn. However, step 504 may also be optional and the algorithm may work based on detecting the steering angle exceeding the threshold alone (at step 502), and then proceeding directly to step 506, in which step the specific suspension adjustments are selected based on the direction and magnitude of the turn. However, in embodiments where the speedometer is also polled at step 504 so as to include consideration of the vehicle's speed of travel in the calculation of the suspension adjustments to be made, as further described above, then both the speed and steering angle measured in step 504 are taken into account in selecting the suspension adjustments at 506. At step 508, the selected suspension adjustments are implemented by increasing the pressure in rear inside B chamber of the suspension spring correlating to the rear inside corner of the turning vehicle. For example, by way of illustration only, if a vehicle is turning right (from the perspective of the driver of vehicle), then the rear inside B chamber 32b, referring to
The algorithm would then proceed to step 510 where the steering sensor is again polled to determine when vehicle 1 has completed the turn. In step 512, once the measured steering angle falls below the threshold angle, indicating the vehicle has exited the turn, the algorithm proceeds to step 514 wherein the suspension springs would be adjusted to the state they were in immediately prior to the algorithm described in
With reference again to
When suspension system 10 enters sway bar state 170, the pressure is increased in all of the B chambers in each of the air spring 20b, 22b, 30b and 32b by an equal amount. Optionally, in some embodiments of the sway bar state 170, the rear B chambers 30b, 32b may have slightly greater pressures than the front B chambers 20b, 22b, depending on the preference of the driver or user of the vehicle and the vehicle performance required. The applicant observes that the sway bar setting adjustments to the suspension spring B chambers, described herein, has the effect of firming or stiffening the suspension springs, causing them to travel less when the vehicle travels over uneven terrain and thereby stabilizing the vehicle and reducing the roll of the vehicle when travelling at moderate speeds over moderately rough terrain.
Finally, suspension system 10 may also include a crossover state 180, an example of an algorithm for which is provided in
In the crossover state 180, the one or more crossover valves 41 may be selectively opened so as to allow fluid communication between the upper chambers connected by a crossover line, such as between 20a, 22a or between 30a, 32a. Opening the crossover valve 41 enables the pressure to become balanced as between the A chambers connected by the crossover line 43 and the open crossover valve 41. The crossover function 180 may be particularly useful for example in situations where one wheel encounters a very large obstacle, thereby exerting an upward force on that one wheel and corresponding suspension spring, thereby increasing the pressure of the A chamber in that spring. In such situations, it is helpful to equalize the pressure between the suspension spring encountering the obstacle and the adjacent suspension spring on the same axle of the vehicle, so as to lower the pressure of the A chamber of the suspension spring that is crossing over the obstacle while at the same time increasing the pressure in the A chamber of the adjacent suspension spring on the other side of the axle. Doing so has the effect of lowering the corner of the vehicle that is crossing over the obstacle, while at the same time, by virtue the pressurizing the adjacent A chamber, the opposite wheel which may not have much or any traction may be brought into contact with the ground. In the applicant's experience in been found that such a crossover function is particularly useful for the front axle of the vehicle 1, however, in some situations it may also be useful to use the crossover function on the rear axle of the vehicle; however this is optional and not required to achieve the desired result being able to cross over most obstacles.
An example of an algorithm for carrying out the crossover function in state 180 is illustrated in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2956933 | Feb 2017 | CA | national |
This application claims priority from U.S. Provisional Patent Application No. 62/454,422, filed on Feb. 3, 2017 and Canadian Patent Application No. 2,956,933, filed on Feb. 3, 2017, both entitled: “Active Suspension Control System and Method for No-Road Vehicles” entireties of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CA2018/000019 | 1/31/2018 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62454422 | Feb 2017 | US |
