CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This PCT International Patent Application claims the benefit of and priority to U.S. Provisional Patent Application Serial No. 62/884,362 filed on August 8, 2019, and titled “Hydro-Elastic Suspension,” the entire disclosure of which is hereby incorporated by reference.

FIELD

[0002j The present disclosure relates generally to vehicle suspension systems. More specifically, the present disclosure relates to vehicle suspension systems including active hydro-elastic units

BACKGROUND

[0003] Excessive ride height of vehicles traveling at highway speeds can have detrimental effects on fuel economy or electric vehicle range. Lowering conventional suspension systems generally results in increased spring rates and poor ride characteristics.

Independent control of ride height, spring rate, and damping characteristics is not generally available vehicle suspension systems.

SUMMARY

[0005) The present disclosure provides a suspension for a vehicle that includes a knuckle configured to hold a wheel and to allow the wheel to rotate; and a hydro-elastic unit operably disposed between the frame structure and the knuckle, the hydro-elastic unit configured to function as a spring and as a damper and including a body of resilient material defining a cavity filled with a liquid, a body defining a port configured to convey the liquid into and out of the cavity for independently adjusting a height of the vehicle and a spring rate of the hydro-elastic unit. [0006] The present disclosure provides a suspension system for a vehicle, the suspension system comprising: a hydro-elastic unit supporting a frame member of the vehicle upon an articulating suspension member, the hydro-elastic unit functioning as a spring and as a damper and comprising a body of resilient material defining a cavity filled with a liquid, the body defining a port configured to convey liquid into and out of the cavity; a hydraulic line in fluid communication with the port to convey the liquid into or out of the cavity; and a flow control valve configured to regulate a flow of the liquid to and/or from the hydro-elastic unit and configured to independently adjust a ride height of the vehicle and a spring rate of the hydro-elastic unit.

[0007] The present disclosure also provides a method of controlling a suspension system for a vehicle. The method includes adjusting a flow control valve to control a flow of liquid between a header and a chamber of a hydro-elastic unit within the suspension system of the vehicle; changing a height of the vehicle by adjusting a volume of the liquid within the chamber of the hydro-elastic unit; and changing a spring rate of the hydro-elastic unit by adjusting a pressure of the liquid within the chamber of the hydro-elastic unit.

BRIEF DESCRIPTION OF THE DRAWINGS [0008] Further details, features and advantages of designs of the invention result from the following description of embodiment examples in reference to the associated drawings.

[0009] FIG. 1 shows a schematic diagram of a conventional suspension apparatus for a wheel of a vehicle;

[0010] FIG. 2 shows a schematic diagram of a conventional suspension apparatus for a wheel of a vehicle;

[0011] FIG. 3 shows a schematic diagram of a conventional suspension apparatus for a wheel of a vehicle; [0012] FIG. 4 shows a schematic diagram of a suspension apparatus for a wheel of a vehicle in accordance with some embodiments of the present disclosure;

[0013] FIG. 5 shows a cut-away side view of a hydro-elastic unit in accordance with some embodiments of the present disclosure;

[0014] FIG. 6 shows a schematic diagram of a suspension system for a vehicle in accordance with some embodiments of the present disclosure;

[0015] FIG. 7 shows a schematic diagram of a suspension system for a vehicle in accordance with some embodiments of the present disclosure;

[0016 j FIG. 8 shows a cut-away side view of a flow control valve in accordance with some embodiments of the present disclosure; and

[0017] FIG. 9 is a graph showing characteristics of hydro-elastic unit in accordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION

[0018] Referring to the drawings, the present invention will be described in detail in view of following embodiments. In some embodiments, the suspension system and hydro elastic units of the present disclosure provide independent control of ride height and spring rate.

[0019] In short, the hydro-elastic units operate on the principle that liquids are incompressible, so the active volume of a rubber spring can be changed as fluid is pumped into or out of it. This allows the spring rate of a hydro-elastic unit to be varied by changing the volume of liquid within a cavity of the hydro-elastic unit, thereby changing the operating pressure and thus the reaction force at any given ride height.

[0020] Suspension systems constructed in accordance with the present disclosure may provide mutually independent variable ride height and variable spring rate, which may be used in an advanced skateboard design including a frame and powertrain that may be used in any of several different vehicle designs.

[0021] Suspension systems constructed in accordance with the present disclosure may provide adjustment that allows reduced ground clearance at highway speeds. Each inch of highway /freeway ground clearance may add between 1 and 2% to energy consumption of a vehicle as a result of increased drag. Energy consumption is critical to battery size and cost, as well as platform flexibility.

[0022] Adjustable ride height and spring rates, as provided by systems constructed in accordance with the present disclosure may provide several other operating advantages by meeting different requirements for ride height and/or spring rate at different times. For example, the EPA truck classification requires 8” ground clearance at curb weight. For light loads and smooth roads, low spring rates are desirable for a smoother ride. When mass increases 40% due to payload, spring rate must be increased 40% to maintain the same ride frequency. Adjustable ride height and/or spring rate may also be used for off-road and rough-road use, e.g. to avoid bottoming out under the same compression loads as a conventional linear-sprung truck, while also providing more ground clearance. In some embodiments, a system constructed in accordance with the present disclosure may provide 20% more ground clearance when compared with a conventional linear-sprung suspension system.

[0023] FIG. 1 shows a schematic diagram of a conventional suspension apparatus for a wheel of a vehicle. Specifically, FIG. 1 shows a knuckle 10 with a lower control arm 12 having a lower inboard pivot 14 for coupling to a frame structure (not shown) and a lower outboard pivot 15 coupling the lower control arm 12 to the knuckle 10 for allowing the knuckle 10 and a wheel attached thereto (not shown) to move up and down relative to the frame of the vehicle. An axle 16 connects to a hub 18 on the knuckle 10 for driving the wheel. A telescopic damper 20 includes a damper housing 22 connected to the frame structure and a damper rod 24 connected to a top of the knuckle 10 spaced apart from the lower outboard pivot 15. A coil spring 26 wraps around the telescopic damper 20. Coil springs 26 and telescopic dampers 20 package conveniently together.

[0024] FIG. 2 shows a schematic diagram of a conventional suspension apparatus for a wheel of a vehicle. Specifically, FIG. 2 shows a suspension apparatus with a short- long arms (SLA) type double-wishbone setup that includes a knuckle 10 and lower control arm 12, similar to those shown in FIG. 1. The SLA suspension apparatus of FIG. 2 includes the damper rod 24 coupled to the lower control arm 12 via a damper fork 28 that straddles around the axle 16. The SLA suspension apparatus of FIG. 2 also includes an upper control arm 30 that is shorter than the lower control arm 12, and which extends between an upper inboard pivot 32 and an upper outboard pivot 33. The upper inboard pivot 32 pivotably connects the upper control arm 30 to the frame structure (not shown), and the upper outboard pivot 33 pivotably connects the upper control arm 30 to the top of the knuckle 10, spaced apart from the lower outboard pivot 15.

[0025] FIG. 3 shows a schematic diagram of another conventional suspension apparatus for a wheel of a vehicle. The suspension apparatus of FIG. 3 is similar to the SLA configuration shown in FIG. 2, but without the telescopic damper 20. Instead, the suspension apparatus of FIG. 3 includes a torsion bar 34 disposed at the lower inboard pivot 14 to act as a spring, and a rotary damper 36 coupled to the knuckle 10 via a damper coupling 38. Mounting the damper concentric to the lower outboard pivot 15 and the torsion bar 34 to the lower inboard pivot 14 provides a relatively tight package. In some embodiments, and as shown in FIG. 3, the damper coupling 38 connects to the knuckle 10 at the lower outboard pivot 15, but the damper could connect to the knuckle 10 or one of the control arms 12, 30 at any location. Alternatively, the rotary damper 36 may be coupled directly to one of the pivots 14, 15, 32, 33 for damping motion of the knuckle 10 relative to the frame structure.

[0026] FIG. 4 shows a schematic diagram of a suspension apparatus for a wheel of a vehicle in accordance with some embodiments of the present disclosure. The suspension apparatus of FIG. 4 is similar to the SLA configuration shown in FIG. 2, but without the telescopic damper 20. Instead, the suspension apparatus of FIG. 3 includes a hydro-elastic unit 46 disposed between the lower control arm 12 and a frame structure 40, such as a frame rail, a unibody, a bracket or other structural member attached to the vehicle. The hydro elastic unit 46 functions as both a spring and a damper. A hydraulic line 48 couples the hydro-elastic unit 46 to an external hydraulic circuit. In some embodiments, the hydro elastic unit 46 functions as both a spring and a damper. The example embodiment of FIG. 3 includes the hydro-elastic unit 46 disposed between a frame structure 40 and an articulating suspension member in the form of the lower control arm 12. However, in other embodiments, the hydro-elastic unit 46 may be disposed between the frame structure 40 and a different articulating suspension member, such as the upper control arm 30, or the knuckle 10, for example.

[0027] FIG. 5 shows a cut-away side view of a hydro-elastic unit 46 in accordance with some embodiments of the present disclosure. Specifically, the hydro-elastic unit 46 comprises a body 52 of resilient material, such as rubber material, which may be natural or synthetic. The body 52 defines a cavity 54 configured to contain a hydraulic fluid. The hydraulic fluid may be a liquid, such as oil, that is non-compressible. The hydro-elastic unit 46 includes a port 56 providing fluid communication between the cavity 54 and external hydraulic circuits, for example, via one or more hydraulic lines 48. In some embodiments, the body 52 of the hydro-elastic unit 46 may be formed similarly or identically to conventional rubber springs. Conventional rubber springs, such as Aeon rubber springs or Hydrolastic units have an inherently high spring rate and damping ratio. In some embodiments, such conventional rubber springs require a high motion ratio and a 5x comer weight load at the frame.

[0028] The hydro-elastic unit 46 shown in FIG. 5 includes two convolutions 58 as segments that are each configured to absorb energy. However, the hydro-elastic unit 46 may include any number of convolutions 58. The body 52 of the hydro-elastic unit 46 absorbs energy by compressing axially and by bulging outwardly. Specifically, each of the two convolutions 58 includes a side wall 60 that extends between an end wall 62 or an interior wall 64 and which is configured to compress axially and to bulge outwardly as indicated by arrow 66 in response to a compressive force between end walls 62 of the hydro-elastic unit 46 as indicated by arrows 68. Similarly, the convolutions 58 are each configured to narrow inwardly in response to a tension force applied to the end walls 62 that is opposite in direction to the arrows 68. The interior wall 64 is relatively thick and/or rigid when compared with the side walls 60 to provide structural rigidity to the hydro-elastic unit 46. In some embodiments, and as shown in FIG. 5, the interior wall 64 defines a channel 70 to provide fluid communication between wide regions 69 of the cavity 54 in adjacent convolutions 58. The wide regions 69 of the cavity 54 each have a relatively large cross sectional area compared with a cross-sectional area of the channel 70. More specifically, the wide regions 69 of the cavity 54 have a relatively large cross sectional area in a plane extending perpendicularly to the direction of compression and/or tension force indicated by the arrows 68. A compressive force may reduce the overall internal volume of the cavity 54 by displacing fluid from the hydro-elastic unit 46 out through the port 56.

[0029] FIG. 6 shows a schematic diagram of a suspension system 100 for a vehicle in accordance with some embodiments of the present disclosure. The suspension system 100 includes an electronic control unit (ECU) 102 that controls operation of various components within the suspension system 100. The ECU 102 may include a processor (not shown) and a machine readable storage medium (not shown) holding instructions for execution by the processor to perform various monitoring and control functions to operate the suspension system 100.

[0030] The suspension system 100 includes a pump 106 in communication with the

ECU 102 and responsive to commands by the ECU 102 to provide pressurized hydraulic fluid within a pressurized header 108. The suspension system 100 also includes a hydro elastic unit 46 between each of one or more front wheels 110 and the frame structure 40, and a hydro-elastic unit 46 between each of one or more rear wheels 112 and the frame structure 40. In some embodiments, each of four wheels of a vehicle has its own independent hydro-elastic unit 46. In some other embodiments, a single hydro-elastic unit 46 may be disposed between an axle holding two or more wheels 110, 112 and the frame structure 40. In this way, the hydro-elastic unit 46 can control the ride height by adjusting a distance between the axle and the frame structure 40.

[003 T| Each of the hydro-elastic unit 46 is in communication with the ECU 102 via a damper communications path 114, such as an electrical cable or cables or a network bus for the ECU 102 to monitor one or more operational parameters of the hydro-elastic unit 46. The operational parameters may include, for example, a pressure within the cavity 54, a temperature of the hydro-elastic unit 46, and/or a position of the hydro-elastic unit 46, which may be determined as a distance between the end walls 62.

[0032] The suspension system 100 shown in FIG. 6 also includes a flow control valve 124 configured to control flow between the pressurized header 124 and an associated one of the hydro-elastic units 46. Each of the flow control valves 124 is connected to the ECU 102 via an electrical conductor 126 for the ECU 102 to control the flow of the hydraulic fluid between the pressurized header 124 and the associated one of the hydro elastic units 46.

[0033] A front height sensor 116 is configured to measure a front height h _f of a front portion of the frame structure 40 from a ground surface 119. A rear height sensor 118 is configured to measure a rear height h _r of a rear portion of the frame structure 40 from the ground surface 119. Together, the height sensors 116, 118 can be used to determine a total height of the frame structure 40, which may vary, for example, based on weight load of the vehicle. The height sensors 116, 118 can also be used to determine an amount of unevenness, which may result, for example, from uneven loading, based on a difference between the front height h _f and the rear height h _r of the frame structure 40. The height sensors 116, 118 may be non-contact sensors, such as an ultrasonic or a radar sensor. Alternatively, one or more of the height sensors 116, 118 may measure the height of the vehicle by measuring a distance or an angle of a component coupled to one of the wheels, such as a suspension component, relative to the frame structure 40. Alternatively, one or more of the height sensors 116, 118 may measure the height of the vehicle by measuring the angular or linear travel of a suspension arm, or the deflection of a suspension spring, such as a hydro-elastic unit 46. A sensor communications path 120, such as an electrical cable or cables or a network bus connects each of the height sensors 116, 118 to the ECU 102 for monitoring the height of the vehicle. In some embodiments, the ECU 102 is configured to adjust one or more of the flow control valves 124 responsive to a height of the frame structure 40 as measured by one or more of the height sensors 116, 118.

[0034] In some embodiments, the ECU 102 is configured to preform load leveling using the hydro-elastic units 46. The ECU 102 may use height data from one or more of the height sensors 116, 118 and/or position data from one or more of the hydro-elastic units 46 to determine the height of the vehicle at each of the wheels 110, 112. The height sensors 116, 118 may be more useful in some cases, such as, for example, where the vehicle is located on uneven or non-level ground.

[0035] FIG. 7 shows a schematic diagram of a suspension system 200 for a vehicle in accordance with some embodiments of the present disclosure. Specifically, the suspension system 200 shown in FIG. 7 includes a pump 202 and a tank 204 holding the hydraulic fluid 206. Each of the pump 200 and the valves 124 shown in the suspension system 200 of FIG. 7 may be coupled to and controlled by an ECU 102 (not shown in FIG. 7). The pump 202 is configured to draw the hydraulic fluid 206 from the tank 204 and to supply the hydraulic fluid 206 to each of the hydro-elastic units 46 via hydraulic lines 48 that function as charged supply lines 210.

[0036] Another hydraulic line 48 functions as a static supply line 212 for conveying the hydraulic fluid 206 from the tank 204 to an associated one of the hydro-elastic units 46. In some embodiments, a check valve (not shown) allows fluid flow through the static supply line 212 from the tank 204 to the associated one of the hydro-elastic units 46 while inhibiting fluid flow in an opposite direction. A flow control valve 124 functions as a supply valve 214 to control the flow of the hydraulic fluid 206 through each of the static supply lines 212.

[0037] Another hydraulic line 48 functions as a return line 216 for conveying the hydraulic fluid 206 from an associated one of the hydro-elastic units 46 back to the tank 204. In some embodiments, a check valve (not shown) allows fluid flow through the return line 216 from the associated one of the hydro-elastic units 46 to the tank 204 while inhibiting fluid flow in an opposite direction. A flow control valve 124 functions as a return valve 218 to control the flow of the hydraulic fluid 206 through each of the static supply lines 212. [0038] As also shown in FIG. 7, another hydraulic line 48 functions as an equalization line 222 for conveying the hydraulic fluid 206 between an associated one of the hydro-elastic units 46 and an equalization header 224. A flow control valve 124 functions as an equalization valve 226 to control the flow of the hydraulic fluid 206 between an associated one of the hydro-elastic units 46 and the equalization header 224.

[0039] FIG. 8 shows a cut-away side view of a flow control valve 124 in accordance with some embodiments of the present disclosure. Specifically, the flow control valve 124 shown in FIG. 8 is a needle valve; however, one or more different types of valves, may be used for the flow control valves 124. For example, one or more of the flow control valves 124 may be spool valves, globe valves, gate valves, ball valves, etc. As shown in FIG. 8, the flow control valve 124 defines an inlet port 302 and an outlet port 304 and is configured to control flow from the inlet port 302 to the outlet port 304. In some embodiments, the flow control valve 124 is configured to be unidirectional, regulating fluid flow in one direction from the inlet port 302 to the outlet port 304. Such a configuration may be used in conjunction with a check valve (not shown) that prevents fluid flow in an opposite direction. Such a check valve may be integral with or independent from the flow control valve 124. In some embodiments, one or more of the flow control valve 124 are configured for bidirectional operation, regulating fluid flow in either of two opposite directions.

[0040] The example flow control valve 124 shown in FIG. 8 includes a needle 308 that is configured to be moved linearly relative to a block 310 to change the size and/or shape of a passage 312 that provides fluid communication between the inlet port 302 and the outlet port 304. The flow control valve 124, thus regulates the flow of fluid between the inlet port 302 and the outlet port 304 by changing a position of the needle 308.

[0041] The example flow control valve 124 shown in FIG. 8 also includes a screw

316 threaded within a nut 318 that is fixed within the flow control valve 124. The screw 316 is turned by a driven member 320, such as a motor shaft or an output of a reduction gearset. When turned within the nut 318, the screw 316 translates rotary motion to axial motion that acts upon the needle 308. A bushing 322 is disposed between the screw 316 and the needle 308 for transmitting axial force therebetween while allowing the screw 316 to rotate independently of the needle 308. A seal 324, such as an O-ring is disposed within the nut 318 and around the screw 316 for preventing fluid from leaking around the screw 316. A seat 326 is also disposed around the screw 316 for providing additional stability and/or additional sealing against leaks of the hydraulic fluid. In some embodiments, the screw 316 may be configured to only provide axial force in a single direction, toward the needle 308, and the flow control valve 124 may rely upon a fluid pressure differential between the inlet port 302 and the outlet port 304 to move the needle 308 away from the block 310. In other embodiments, such as those configured for bidirectional flow, the screw 316 may be configured to provide either of a pushing or a pulling axial force to the needle 308, thus driving the needle 308 into or out of the block 310.

[0042| FIG. 9 is a graph 400 showing characteristics of hydro-elastic unit 46 in accordance with some embodiments of the present disclosure. Graph 400 plots loads in pounds, on the y-axis vs. deflection in inches on the x-axis. Specifically, the graph 400 includes a first line 402 showing characteristics of a hydro-elastic unit 46 in a compression condition, and a second line 404 showing characteristics of a hydro-elastic unit 46 in a rebound condition. The graph 400 illustrates a few regions of interest on the first line 402 including a first region 410 having a relatively small load and a relatively small displacement (i.e. large amount of ground clearance). This first region 410 may be used for trucks or other vehicles carrying relatively light loads (e.g. around town) and is preferably not used for highway or freeway driving, where the large amount of ground clearance results in increased drag and associated fuel consumption costs. The second region 412 has increased deflection, resulting in lower ride height and thus, increased fuel economy in highway driving conditions. A hydro-elastic unit 46 of the present disclosure may be operated in the second region 412 instead of the first region 410 by removing fluid therefrom. In some embodiments, a hydro-elastic unit 46 of the present disclosure operated in the second region 412 by removing fluid therefrom may have a small increase in spring rate when compared to the same hydro-elastic unit 46 operated in the first region 410. The third region 414 corresponds to a loaded vehicle, having a much higher load than either or the first or second regions 410, 412. The third region 414 has a relatively large spring rate and a relatively large deflection when compared with each of the first or second regions 410, 412. However, in some embodiments, the spring rate, and thus the handling characteristics, may be dynamically adjusted by adding or removing hydraulic fluid from the hydro-elastic unit 46. The ride height can also be increased by the addition of fluid to the hydro-elastic unit 46. This increased ride height may allow adequate travel before bottoming, while still having the spring rate follow the steeper region of the first line 402, for example around, within or above the third region 414.

[0043] A method of controlling a suspension system for a vehicle is also provided in the present disclosure. The method includes adjusting a valve to control a flow of liquid between a header and a chamber of a hydro-elastic unit within the suspension system of the vehicle; changing a height of the vehicle by adjusting a volume of the liquid within the chamber of the hydro-elastic unit; and changing a spring rate of the hydro-elastic unit by adjusting a pressure of the liquid within the chamber of the hydro-elastic unit.

[0044] In some embodiments, the method also includes adjusting a damping characteristic of the hydro-elastic unit by regulating a flow of fluid between the pressurized header and the chamber of the hydro-elastic unit. In some embodiments, the valve is a needle valve that includes a needle configured to move linearly to control the flow of fluid through the valve. In some embodiments, the method also includes adjusting the valve in response to a position of the hydro-elastic unit. In some embodiments, the method also includes adjusting the valve in response to a height of a frame structure of the vehicle relative to the ground. More specifically, the method may include monitoring the height of the frame structure of the vehicle using a height sensor. In some embodiments, monitoring the height of the frame structure includes measuring a front height of a front of the vehicle using a front height sensor, and measuring a rear height of a rear of the vehicle using a rear height sensor. In some embodiments, the method also includes pressurizing the header using a pump.

[0045] The system, methods and/or processes described above, and steps thereof, may be realized in hardware, software or any combination of hardware and software suitable for a particular application. The hardware may include a general purpose computer and/or dedicated computing device or specific computing device or particular aspect or component of a specific computing device. The processes may be realized in one or more microprocessors, microcontrollers, embedded microcontrollers, programmable digital signal processors or other programmable device, along with internal and/or external memory. The processes may also, or alternatively, be embodied in an application specific integrated circuit, a programmable gate array, programmable array logic, or any other device or combination of devices that may be configured to process electronic signals. It will further be appreciated that one or more of the processes may be realized as a computer executable code capable of being executed on a machine readable medium.

[0046] The computer executable code may be created using a structured programming language such as C, an object oriented programming language such as C++, or any other high-level or low-level programming language (including assembly languages, hardware description languages, and database programming languages and technologies) that may be stored, compiled or interpreted to run on one of the above devices as well as heterogeneous combinations of processors processor architectures, or combinations of different hardware and software, or any other machine capable of executing program instructions.

[0047] Thus, in one aspect, each method described above and combinations thereof may be embodied in computer executable code that, when executing on one or more computing devices performs the steps thereof. In another aspect, the methods may be embodied in systems that perform the steps thereof, and may be distributed across devices in a number of ways, or all of the functionality may be integrated into a dedicated, standalone device or other hardware. In another aspect, the means for performing the steps associated with the processes described above may include any of the hardware and/or software described above. All such permutations and combinations are intended to fall within the scope of the present disclosure.

[0048] The foregoing description is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.