Inertial integrated damping system for wheel assembly bushings

Abstract

A wheel assembly bushing for an in-wheel motor, wherein the bushing includes a hydraulic chamber positioned within a resilient sleeve of the bushing and a helical fluid passage extending helically about an inner bushing member between a first fluid passage end and a second fluid passage end arranged in fluid communication with the hydraulic chamber. An outer body extends annularly about the resilient sleeve, which allows for relative motion between the inner bushing member and the outer body. The fluid passage is configured to produce inertia. When combined with other damping and stiffness effects of the wheel assembly bushing, the inertia provides a phase and magnitude shift between force and velocity, which ultimately reduces magnetic gap distortion in the in-wheel motor.

Description

Technical Field

[0001] This disclosure relates in general to bushings used in vehicles. More specifically, this disclosure relates to an inertial integrated damping system incorporated into bushings used in vehicle wheel assemblies and in-wheel electric motors. Background Technology

[0002] This section provides background information relating to this disclosure, which is not necessarily prior art.

[0003] In-wheel electric motors are gaining popularity as both a primary and secondary propulsion solution for plug-in hybrid electric vehicles (PHEVs) and electric vehicles (EVs). Installed within the vehicle's wheels, in-wheel electric motors allow for better torque guidance and offer encapsulation advantages, as they do not occupy additional space within the vehicle body and allow for the elimination of traditional drive shafts.

[0004] A crucial factor in designing in-wheel motors is magnetic gap deformation. Magnetic gap deformation is the relative displacement between the rotor and stator of the motor. High magnetic gap deformation exacerbates high-frequency vibrations experienced in vehicles and can also adversely affect the lifespan and reliability of in-wheel motors. Therefore, this magnetic gap deformation must be limited. When magnetic gap deformation is large, design tolerances require a larger clearance between the rotor and stator, which also reduces the efficiency of the in-wheel motor. In other words, in-wheel motors are most efficient when the clearance between the rotor and stator is small, but magnetic gap deformation imposes design constraints on the size of this clearance, thus requiring the use of larger, less efficient motors. In addition to reduced efficiency, another drawback is that larger, less efficient in-wheel motors increase the unsprung mass of the vehicle because the motor is located inside the wheel. This also reduces ride comfort and tire grip. Therefore, solutions are needed to limit the negative impacts of magnetic gap deformation on vehicles equipped with in-wheel motors. Summary of the Invention

[0005] This section provides the overall inventive summary of this disclosure and is not a complete disclosure of its full scope or all its features. In particular, the description of the physical embodiments of the designs is not intended to limit this disclosure to the specific arrangements and design features of the particular examples shown and described herein.

[0006] According to one aspect of this disclosure, a wheel assembly is provided, comprising a hub, a wheel rotatably mounted on the hub, an in-wheel motor, and at least one wheel assembly bushing. The in-wheel motor includes a stator mounted on the hub and a rotor coupled to the wheel. Thus, the rotor and the wheel rotate together relative to the stator and the hub. The wheel assembly bushing includes an inner bushing member, an outer body, and a resilient sleeve. The outer body of the wheel assembly bushing is concentrically arranged around and radially spaced from the inner bushing member, and the resilient sleeve is radially positioned between the inner bushing member and the outer body.

[0007] The wheel assembly bushing also includes a hydraulic chamber located within a resilient sleeve and a fluid channel extending between a first fluid channel end and a second fluid channel end, the first and second fluid channel ends being arranged in fluid communication with the hydraulic chamber. The resilient sleeve is made of an elastic material, such that it is configured to allow relative movement between the inner bushing member and the outer body. The fluid channel is configured to create a phase delay between an input force causing relative movement between the inner bushing member and the outer body, the reaction force being generated by pressure pulses in the hydraulic chamber caused by fluid flow through the fluid channel. The principle behind this phase delay between the input and reaction forces is called inertia.

[0008] According to another aspect of this disclosure, a wheel assembly bushing is provided, comprising an inner bushing member, an outer body, and a resilient sleeve. The inner bushing member extends axially along a longitudinal axis. The resilient sleeve extends annularly around the inner bushing and is made of an elastic material. The outer body is concentrically arranged around the inner bushing member and radially spaced from it. The outer body extends annularly around the resilient sleeve, such that the resilient sleeve is radially positioned between the inner bushing member and the outer body.

[0009] The hydraulic chamber is positioned within a resilient sleeve. The hydraulic chamber extends annularly within the resilient sleeve and axially between a first hydraulic chamber end and a second hydraulic chamber end. A helical fluid passage extends helically around the inner bushing member between the first and second fluid passage ends. The wheel assembly bushing also includes a partition within the resilient sleeve extending into the hydraulic chamber at a location longitudinally positioned between the first and second hydraulic chamber ends. The partition divides the hydraulic chamber into a first hydraulic chamber segment and a second hydraulic chamber segment. The first fluid passage end of the helical fluid passage is arranged in fluid communication with the first hydraulic chamber segment, and the second fluid passage end of the helical fluid passage is arranged in fluid communication with the second hydraulic chamber segment. Additionally, a fluid passage is provided within the resilient sleeve and / or the partition, allowing fluid to flow around or through the partition, such that fluid can pass between the first and second hydraulic chamber segments.

[0010] In a typical in-wheel motor, the rotor is fixed to the vehicle's wheel, and the stator is fixed to the hub mass. This arrangement does not allow for independent adjustment of the magnetic gap deformation. To reduce the adverse effects of magnetic gap deformation and improve the efficiency of the in-wheel motor, the rotor and stator are isolated from the wheel and hub using the wheel assembly bushing described herein. This effectively reduces magnetic gap deformation in the in-wheel motor without compromising ride comfort (often referred to as vehicle vertical acceleration) and tire grip (often referred to as tire dynamic load).

[0011] Advantageously, the phase delay / inertia generated by the fluid channels in the wheel assembly bushing described herein produces a reaction force proportional to the relative acceleration of the fluid between the ends of the first and second fluid channels. Therefore, using the force-current relationship in a capacitor as an analogy, these components of the wheel assembly bushing described herein act as a mechanical equivalent of a capacitor. The phase delay / inertia generated by the fluid channels in the wheel assembly bushing (collectively forming a fluid-filled inertial track within the wheel assembly bushing), combined with other damping and stiffness effects of the wheel assembly bushing, provides a phase and amplitude shift between the force and the relative motion between the elastic sleeve and the outer body. Such effects significantly enhance the vibration damping capability of the wheel assembly bushing described herein. Attached Figure Description

[0012] The accompanying drawings described herein are for illustrative purposes only for the selected embodiments and not for all possible specific implementations, and are not intended to limit the scope of this disclosure.

[0013] Figure 1 This is a perspective cross-sectional view of an exemplary wheel assembly constructed according to this disclosure;

[0014] Figure 2 yes Figure 1 A front sectional view of an exemplary wheel assembly shown;

[0015] Figure 3 This is a perspective cross-sectional view of an exemplary wheel assembly bushing constructed according to this disclosure;

[0016] Figure 4 yes Figure 3 A side sectional view of an exemplary wheel assembly bushing shown;

[0017] Figure 5 yes Figure 1 A schematic diagram of an exemplary wheel assembly shown;

[0018] Figure 6 It is positioned at Figure 5 A network representation of an exemplary wheel assembly bushing between the hub and stator of the exemplary wheel assembly shown in the figure;

[0019] Figure 7 It is positioned at Figure 5 The network representation of another exemplary wheel assembly bushing between the wheel and rotor of the exemplary wheel assembly shown; and

[0020] Figure 8 It is shown Figure 1 and Figure 2 As shown and in Figure 5 A graph of the frequency response of an exemplary wheel assembly modeled in the model is shown to illustrate the improved vibration damping performance of the exemplary wheel assembly bushing. Detailed Implementation

[0021] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. Where possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts.

[0022] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. Exemplary embodiments are provided so that this disclosure will be thorough and will fully communicate the scope to those skilled in the art. Numerous specific details, such as examples of particular components, apparatus, and methods, are set forth to provide a thorough understanding of embodiments of this disclosure. It will be apparent to those skilled in the art that specific details are not required, that exemplary embodiments may be embodied in many different forms, and should not be construed as limiting the scope of this disclosure. In some exemplary embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.

[0023] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may also be intended to include the plural forms unless the context clearly indicates otherwise. The terms “comprising,” “constituting,” “including,” and “having” are inclusive and thus specify the presence of the stated feature, integer, step, operation, element, and / or component, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Unless there is an explicit order of execution, the method steps, processes, and operations described herein should not be construed as requiring performance in the specific order discussed or described. It should also be understood that additional or alternative steps may be employed.

[0024] When an element or layer is referred to as “on,” “joined to,” “connected to,” or “attached to” another element or layer, the element or layer may be directly on, joined to, connected to, or attached to the other element or layer, or there may be intermediate elements or layers present. Conversely, when an element is referred to as “directly on,” “directly joined to,” “directly connected to,” or “directly attached to” another element or layer, there may be intermediate elements or layers present. Other terms used to describe relationships between elements should be interpreted in a similar manner (e.g., “between” vs. “directly between,” “adjacent” vs. “directly adjacent,” etc.). As used herein, the term “and / or” includes any and all combinations of one or more of the listed items.

[0025] Although the terms first, second, third, etc., are used herein to describe various elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may only be used to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as “first,” “second,” and other numerical terms used herein do not imply sequence or order. Therefore, without departing from the teachings of the exemplary embodiments, the first element, component, region, layer, or segment discussed below may be referred to as a second element, component, region, layer, or segment.

[0026] Spatially related terms such as “inner,” “outer,” “below,” “below,” “lower,” “above,” and “upper” are used herein to describe the relationship of one element or feature to another, as shown in the figures. In addition to the orientations shown in the figures, spatially related terms may also be intended to cover different orientations of the device during use or operation. For example, if the device in the figures is flipped, then an element described as “below” or “below” other elements or features would be oriented as “above” other elements or features. Thus, the exemplary term “below” can cover both above and below orientations. The device can be oriented in other ways (rotated 90 degrees or otherwise), and the spatially related descriptors used herein are interpreted accordingly.

[0027] Figure 1 and Figure 2An exemplary wheel assembly 20 for a vehicle (not shown) is illustrated. The wheel assembly 20 includes a hub 22, a wheel 24 rotatably mounted on the hub 22, and an in-wheel electric motor 26. The hub 22 includes a hub portion 28 and an axle portion 30. The axle portion 30 of the hub 22 has a smaller diameter than the hub portion 28 and is positioned outside the hub portion 28, meaning that the axle portion 30 is farther from the centerline of the vehicle than the hub portion 28. The axle portion 30 of the hub 22 extends from the hub portion 28 to an outer end 32, and a wheel bearing 34 is positioned on the outer end 32 of the axle portion 30 of the hub 22. The wheel 24 includes an attachment portion 36 that includes a central bore 38 and a plurality of bolt holes 40 circumferentially spaced around the central bore 38. The wheel 24 also includes spokes 42 that extend radially outward from the attachment portion 36 to an outer rim 44 supporting a tire 46. The wheel 24 is mounted on the wheel bearing 34, wherein the outer end 32 of the axle portion 30 of the hub 22 and the wheel bearing 34 are received in the center hole 38 of the wheel 24. In this way, the wheel 24 is supported on the axle portion 30 of the hub 22 and can rotate relative to the axle portion about the axis of rotation 48.

[0028] The in-wheel motor 26 includes a stator 50 and a rotor 52. The stator is mounted on a hub 22, and the rotor is connected to a wheel 24 by a plurality of wheel bolts 54 extending through bolt holes 40 in the wheel 24 and screwed into threaded holes 56 in the base 58 of the rotor 52. In the illustrated example, the wheel 24 includes four bolt holes 40 that receive four wheel bolts 54. However, it should be understood that the number of wheel bolts 54 and bolt holes 40 may vary depending on the vehicle. Alternatively, the wheel 24 may be configured in a center-locked configuration, wherein a single / center wheel bolt or fastener attaches the wheel 24 to the base 58 of the rotor 52. Regardless of the configuration, the rotor 52 and the wheel 24 rotate together with respect to the stator 50 and the hub 22. The stator 50 includes an inner portion 60 and an outer portion 62. The inner portion 60 of the stator 50 extends annularly around and is supported on the hub portion 28 of the hub 22, while the outer portion 62 of the stator 50 extends annularly around and is supported on the shaft portion 30 of the hub 22. The outer portion 62 of the stator 50 includes a cylindrical base 64 extending annularly around the shaft portion 30 of the hub 22 and a disk portion 66 extending radially outward from the cylindrical base 64 to an outer peripheral ring 68. The base 58 of the rotor 52 includes a central cavity 70 that accommodates a rotor bearing assembly 72. The rotor bearing assembly 72 extends annularly between the cylindrical base 64 of the stator 50 and the base 58 of the rotor 52. The rotor 52 includes a transverse body 74 that extends radially outward from the base 58 of the rotor 52 to a circumferential housing 76 that extends around and surrounds the outer peripheral ring 68 of the stator 50. In this way, a magnetic gap 78 is formed between the circumferential housing 76 of the rotor 52 and the outer circumferential ring 68 of the stator 50.

[0029] Optionally, the wheel assembly 20 also includes a brake disc 80 and a brake caliper 82. In the illustrated example, the brake caliper 82 is fixed to the inner portion 60 of the stator 50, and the brake disc 80 is fixed to the rotor 52 and extends radially inward from the circumferential housing 76, such that the brake disc 80 and the rotor 52 rotate together with respect to the brake caliper 82. However, it should be understood that alternative configurations are possible. For example, the brake caliper 82 may alternatively be mounted to the hub portion 28 of the wheel hub 22.

[0030] Figure 1 and Figure 2The wheel assembly 20 shown also includes a plurality of wheel assembly bushings 84a, 84b, and 84c. Specifically, the wheel assembly 20 includes a first wheel assembly bushing 84a positioned between the hub portion 28 of the hub 22 and the inner portion 60 of the stator 50. The wheel assembly 20 also includes a second wheel assembly bushing 84b positioned between the shaft portion 30 of the hub 22 and the cylindrical base 64 of the outer portion 62 of the stator 50. Thus, the first wheel assembly bushing 84a and the second wheel assembly bushing 84b are radially positioned between the hub 22 and the stator 50 at longitudinally spaced locations. Finally, the wheel assembly 20 includes one or more third wheel assembly bushings 84c positioned in bolt holes 40 between the wheel bolts 54 and the wheel 24. Although a total of four third wheel assembly bushings 84c are shown in the example, one third wheel assembly bushing for each wheel bolt 54, it should be understood that wheel assembly 20 may include a different number of third wheel assembly bushings 84c. For example, a single third wheel assembly bushing 84c may be used in a center-locking wheel configuration.

[0031] For further reference Figure 3 and Figure 4 Each of the wheel assembly bushings 84a to 84c includes an inner bushing member 86, an outer body 88, and a resilient sleeve 90. The outer body is concentrically arranged around the inner bushing member 86 and radially spaced from it. The resilient sleeve is radially positioned between the inner bushing member 86 and the outer body 88. The inner bushing member 86 extends axially along a longitudinal axis 92, which is aligned with or parallel to the axis of rotation 48 of the wheel 24. The resilient sleeve 90 extends annularly around the inner bushing member 86, and the outer body 88 extends annularly around the resilient sleeve 90, such that the resilient sleeve 90 is radially positioned between the inner bushing member 86 and the outer body 88. The elastic sleeve 90 is made of an elastic material, such as rubber or another elastomeric material, which is configured to allow relative movement between the inner bushing member 86 and the outer body 88 when the wheel 24 travels on bumps or potholes and / or during acceleration, braking and cornering maneuvers, when input forces are applied to the inner bushing member 86 and / or the outer body 88 of the wheel assembly bushings 84a, 84b, 84c.

[0032] Hydraulic chambers 94 are positioned within the resilient sleeves 90 of each wheel assembly bushing 84a to 84c. Hydraulic chambers 94 are filled with fluid, such as oil or hydraulic fluid. Hydraulic chambers 94 extend annularly within the resilient sleeves 90 and axially between a first hydraulic chamber end 96 and a second hydraulic chamber end 98. Each wheel assembly bushing in wheel assembly bushings 84a to 84c also has a helical fluid passage 100 extending helically (i.e., in a helical form) around an inner bushing member 86. In the illustrated example, the helical fluid passage 100 is formed by helical grooves in both the inner bushing member 86 and the resilient sleeve 90; however, it should be understood that the helical fluid passage 100 may alternatively be formed only in the resilient sleeve 90 or only in the inner bushing member 86. The helical fluid channel 100 has a first fluid channel end 102 and a second fluid channel end 104. The first fluid channel end leads to and is arranged in fluid communication with a first hydraulic chamber end 96 (i.e., the first fluid channel end 102 is configured as an opening in the first hydraulic chamber end 96), and the second fluid channel end leads to and is arranged in fluid communication with a second hydraulic chamber end 98 (i.e., the second fluid channel end 104 is configured as an opening in the second hydraulic chamber end 98). A partition 106 within the resilient sleeve 90 extends into the hydraulic chamber 94 at a location longitudinally positioned between the first hydraulic chamber end 96 and the second hydraulic chamber end 98. For example, in the illustrated embodiment, the partition 106 is an annular, radially extending wall integral with the resilient sleeve 90 and made of the same material as the resilient sleeve. However, it should be understood that the partition 106 may alternatively be a separate or molded component of the wheel assembly bushings 84a to 84c. Regardless of the construction, the partition 106 divides the hydraulic chamber 94 into two hydraulic chamber sections 108 and 110, which are arranged to be in fluid communication with each other via a fluid passage 112, which is designed to restrict fluid flow and thus generate a drag / damping coefficient.

[0033] Hydraulic chamber sections 108 and 110 include a first hydraulic chamber section 108 arranged in fluid communication with a first fluid passage end 102 and a second hydraulic chamber section 110 arranged in fluid communication with a second fluid passage end 104. In the illustrated embodiment, fluid passage 112 allows fluid to flow between the first hydraulic chamber section 108 and the second hydraulic chamber section 110 and is configured as an annular opening in the partition 106. However, it should be understood that other configurations are possible, and depending on the ultimately identified network, the partition 106 may be placed in other locations. For example, fluid passage 112 may be one or more holes or orifices in the partition 106, or alternatively, one or more fluid paths disposed in the resilient sleeve 90. Regardless of the construction, fluid passage 112 forms a pinch in hydraulic chamber 94 that restricts fluid flow between the first hydraulic chamber section 108 and the second hydraulic chamber section 110, such that a temporary pressure differential between the first hydraulic chamber section 108 and the second hydraulic chamber section 110 can be generated over a period of time by fluid flow through helical fluid passage 100 in response to the deflection of resilient sleeve 90, until the total fluid flow through both fluid passage 112 and helical fluid passage 100 equalizes the pressure in the first hydraulic chamber section 108 and the second hydraulic chamber section 110. As will be explained in more detail below, fluid passage 112 and helical fluid passage 100 cooperate to produce a phase and amplitude offset between the input forces causing relative movement between inner bushing member 86 and outer body 88 and deflection of resilient sleeve 90. The relative motion within the wheel assembly bushings 84a, 84b, and 84c generates a reaction force caused by pressure pulses in the hydraulic chamber 94, which are caused by fluid flow from one end of the hydraulic chamber 94 to the other through the fluid passage 112 and the spiral fluid passage 100.

[0034] refer to Figures 1 to 4 It should be understood that the inner bushing member 86 and outer body 88 of each wheel assembly bushing 84a, 84b, 84c may have different constructions and may be separate components or integrated into the components of the wheel assembly 20. For example, the inner bushing member 86 of the first wheel assembly bushing 84a may be a cylindrical sleeve that extends annularly around and abuts the hub portion 28 of the hub 22, while the outer body 88 of the first wheel assembly bushing 84a may be a cylindrical sleeve that is received within and abuts the inner portion 60 of the stator 50. Alternatively, the inner bushing member 86 of the first wheel assembly bushing 84a may be integral with the hub portion 28 of the hub 22, and / or the outer body 88 of the first wheel assembly bushing 84a may be integral with the inner portion 60 of the stator 50. Regardless of the construction, the elastic sleeve 90 of the first wheel assembly bushing 84a is radially positioned between the hub portion 28 of the hub 22 and the inner portion 60 of the stator 50.

[0035] For the second wheel assembly bushing 84b, the inner bushing member 86 may be a cylindrical sleeve extending annularly around and abutting the shaft portion 30 of the hub 22, while the outer body 88 of the second wheel assembly bushing 84b may be a cylindrical sleeve received within and abutting the outer portion 62 of the stator 50. Alternatively, the inner bushing member 86 of the second wheel assembly bushing 84b may be integral with the shaft portion 30 of the hub 22, and / or the outer body 88 of the second wheel assembly bushing 84b may be integral with the outer portion 62 of the stator 50. Regardless of the construction, the resilient sleeve 90 of the second wheel assembly bushing 84b is radially positioned between the shaft portion 30 of the hub 22 and the outer portion 62 of the stator 50.

[0036] The outer body 88 of the third wheel assembly bushing 84c can be configured as a cylindrical sleeve received within the bolt hole 40 in the wheel 24, while the inner bushing member 86 can be a cylindrical sleeve in the third wheel assembly bushing 84c that receives the wheel bolt 54. Alternatively, the inner bushing member 86 of the third wheel assembly bushing 84c can be integral with the wheel bolt 54, and / or the outer body 88 of the third wheel assembly bushing 84c can be integral with the wheel 24. Regardless of the configuration, the resilient sleeve 90 of the third wheel assembly bushing 84c is positioned between the wheel bolt 54 and the wheel 24.

[0037] Figures 5 to 7 This illustrates how the aforementioned wheel assembly 20 can be modeled as a spring-mass system. A first wheel assembly bushing 84a and a second wheel assembly bushing 84b combine to create a bushing interface between the stator 50 of the in-wheel motor 26 and the hub 22, while a third wheel assembly bushing 84c provides a bushing interface between the rotor 52 of the in-wheel motor 26 and the wheel 24. It is important to note that the third wheel assembly bushing 84c can represent multiple bushings surrounding the wheel 24. The x0 parameter represents the position of the road surface, the x1 parameter represents the displacement of the wheel 24, and the x2 parameter represents the displacement of the vehicle body. Labeled as x... 31 The parameter represents the displacement of hub 22, x 32 The parameter represents the displacement of stator 50, and x 33 The parameter represents the displacement of rotor 52. The mass of wheel 24 is represented by parameter m1, the sprung mass of the vehicle is represented by parameter m2, and the mass of hub 22 is represented by parameter m... 31 The parameters indicate that the mass of stator 50 is determined by m. 32 The parameters represent the mass of rotor 52, and the mass of rotor 52 is determined by m. 33The parameters are represented as follows: Tire 46 itself acts as a spring and has a stiffness represented by parameter k1, while the stiffness of the vehicle's suspension struts (e.g., disc springs) is represented by parameter k2. The damping coefficient of the vehicle damper is shown by parameter c2. The spring-mass subsystem labeled G(s) shows the combination of the first wheel assembly bushing 84a and the second wheel assembly bushing 84b, while the spring-mass subsystem Y(s) shows the third wheel assembly bushing 84c. The combined static stiffness of the elastic sleeve 90 in both the first wheel assembly bushing 84a and the second wheel assembly bushing 84b is represented by parameter k. 31 The combined static stiffness of the elastic sleeve 90 in the third wheel assembly bushing 84c is indicated by parameter k. 32 The wheel bearing 34 and rotor bearing assembly 72 also have spring constants, which are respectively determined by the parameter k. 41 and k 42 express.

[0038] Figure 6 The spring-mass subsystem G(s) shown, which models the combination of the first wheel assembly bushing 84a and the second wheel assembly bushing 84b, has a stiffness k. 51 Damping coefficient c 51 and inertia b 51 Similarly, Figure 7 The spring-mass subsystem Y(s) modeled for the third wheel assembly bushing 84c, as shown, also has a stiffness k. 52 Damping coefficient c 52 and inertia b 52 The values ​​of these design parameters for the spring-mass subsystems G(s) and Y(s) can be determined using the optimization process described below.

[0039] First, calculate the reference performance values ​​of the rubber bushing using the following formula:

[0040]

[0041]

[0042]

[0043] In the above formula, J1, J3, and J M Let X represent the H2 norm of vertical vehicle acceleration, dynamic tire load, and magnetic gap deformation under random road input in the Laplace domain. V is the vehicle velocity, κ is the road roughness parameter, s is the Laplace operator, ||-||² represents the H2 norm, and X... n It is the Laplace transform of the mass displacement.

[0044] In the above J1, J3 and J mThe spectral density of the time-varying displacement of the road surface used in the relation can be described by the following formula:

[0045]

[0046] In the above formula, f is the frequency in Hz (cycles per second), V is the vehicle speed, n is the wave number in cycles per meter, and f = nV. Parameters and These represent the spectral density of the time-varying displacement of the road surface and the corresponding spectral density of the time-varying velocity of the road, respectively.

[0047] The parameter values ​​used in these calculations are listed in Table 1 below:

[0048] Table 1: Parameter Values

[0049]

[0050] When using the above values, the baseline performance value is:

[0051] J1 = 1.4915 m / s 2 ,

[0052] J3 = 953.87 N,

[0053] J M =7.4361μm.

[0054] When wheel assembly bushings 84a to 84c are optimized to reduce magnetic gap deformation J M These calculated values ​​are then used as constraints to ensure that the magnetic gap deformation J M The improvements will not reduce the performance of vertical vehicle acceleration J1 and dynamic tire load J3.

[0055] When the reference rubber bushing is replaced by the wheel assembly bushings 84a to 84c described herein, eight different topological combinations are provided, including a spring element, a damper element, and an inertial element. These eight different layouts represent all possible combinations of these three elements. Using the above optimization process, the inventors confirmed... Figures 6 to 7 The specific layout of the inertial integrated wheel assembly bushings 84a to 84c shown provides optimal performance values, wherein vertical vehicle acceleration J1, dynamic tire load J3, and magnetic gap deformation J M The values ​​are as follows:

[0056] J1 = 1.4614 m / s 2 ,

[0057] J3 = 953.87 N,

[0058] J M=1.2207μm.

[0059] In other words, using Figures 6 to 7 The network structure shown, magnetic gap deformation J M The rubber bushing was reduced by 83.584% compared to the baseline. Meanwhile, the performance values ​​of vertical vehicle acceleration J1 and dynamic tire load J3 did not decrease (in fact, Figures 6 to 7 The arrangement shown provides a 2.0181% improvement in vertical vehicle acceleration J1.

[0060] Advantageously, by reducing the magnetic gap deformation J M Without reducing the performance values ​​of vertical vehicle acceleration J1 and dynamic tire load J3, the wheel assembly bushings 84a to 84c described herein allow the use of in-wheel electric motors 26 with a smaller clearance between the rotor 52 and the stator 50. Because the in-wheel electric motor 26 is most efficient when the clearance between the rotor 52 and the stator 50 is small, the wheel assembly bushings 84a to 84c described herein allow the use of smaller, more efficient in-wheel electric motors 26. Advantageously, these smaller, more efficient in-wheel electric motors 26 reduce the unsprung mass of the vehicle, which improves performance, ride comfort, and tire grip.

[0061] Figures 1 to 4 The wheel assembly 20 and wheel assembly bushings 84a to 84c shown are Figures 5 to 7 The physical example of the topology shown illustrates how inertia is integrated into the wheel assembly bushings 84a to 84c using a fluid-filled inertial track provided by a hydraulic chamber 94 and a helical fluid channel 100, to achieve the inertial value b calculated above. According to Figure 3 and Figure 4 The wheel assembly bushings 84a to 84c shown are designed such that the relative motion between the outer body 88 and the inner bushing member 86 propels fluid through the helical fluid channel 100. The length and area of ​​the helical fluid channel 100, as well as the fluid density, contribute to the experienced inertial effect. This inertia b can be calculated using the following formula:

[0062]

[0063] In the above formula, A1 is the area of ​​the hydraulic chamber 94, A2 is the area of ​​the helical fluid channel 100, ρ is the fluid density, and the l parameter is the unfolded length of the helical fluid channel 100. By carefully designing the helical fluid channel 100 and selecting appropriate fluid and elastic materials for the elastic sleeve 90, the stiffness, damping, and inertia of the wheel assembly bushings 84a to 84c can be optimized according to the above calculations. Any physical implementation will need to be constructed based on the parameter values ​​obtained through the optimization process. These parameter values ​​are shown in Table 2 below:

[0064] Table 2: Parameter values ​​for the bushing used for optimization

[0065]

[0066] The phase delay / inertia generated by the helical fluid channels 100 of the wheel assembly bushings 84a to 84c described herein produces a reaction force proportional to the relative acceleration of the fluid between the first fluid channel end 102 and the second fluid channel end 104. Therefore, using the force-current relationship in a capacitor as an analogy, the helical fluid channels 100 of the wheel assembly bushings 84a to 84c described herein serve as a mechanical equivalent of a capacitor. The phase delay / inertia generated by the helical fluid channels 100 forming the fluid-filled inertial tracks within the wheel assembly bushings 84a to 84c significantly enhances the vibration damping function of the wheel assembly bushings 84a to 84c described herein. The effect of this on the wheel assembly 20 results in… Figure 8 As shown in the image.

[0067] Figure 8 This is a graph comparing the frequency domain response of the baseline rubber bushing and the optimized wheel assembly bushings 84a to 84c described herein with a random road input. Figure 8 In the graph, the x-axis represents the frequency of the domain response to the road input, measured in Hertz (Hz). The y-axis represents the absolute amplitude of the domain response to the road input, measured in x10⁻⁶. -4 The multiplier ratio is shown as (i.e., the listed y-axis values ​​are multiplied by 10). -4 For example, listing an absolute value as "2" on the y-axis represents an absolute value of 0.0002. Figure 8 The domain response curve, shown as a solid line, provides a benchmark for the magnitude of the response to road inputs in the wheel assembly 20, where, before any optimization is performed, the rotor 52 of the in-wheel motor 26 is mounted to the vehicle's wheel 24, and the stator 50 of the in-wheel motor 26 is mounted to the wheel hub 22 with rubber bushings. Figure 8 The domain response curves shown as solid lines with dashed segments illustrate the amplitude of the response to road inputs in the wheel assembly 20 equipped with rubber bushings between the rotor 52 and wheel 24, and between the stator 50 and hub 22, wherein these rubber bushings have undergone the same optimization process discussed in this patent. Figure 8 The domain response curve shown as a dashed line illustrates the amplitude of the response to road inputs in wheel assembly 20 equipped with wheel assembly bushings 84a to 84c as described herein.

[0068] like Figure 8As shown, for a wheel assembly 20 equipped with wheel assembly bushings 84a to 84c as described herein, the overall amplitude of the system response is significantly reduced in the frequency domain. Specifically, for a wheel assembly 20 equipped with wheel assembly bushings 84a to 84c as described herein, the peak value of the system response decreases sharply at the natural frequencies (approximately 6.32 Hz and 103 Hz).

[0069] While various aspects of this disclosure have been specifically shown and described with reference to the above embodiments, those skilled in the art will understand that various additional embodiments can be conceived by modifying the disclosed inertial integrated damping system without departing from the spirit and scope of the disclosure. Such embodiments should be understood to fall within the scope of this disclosure as defined by the claims and any equivalents.

Claims

1. A wheel assembly, the wheel assembly comprising: Wheel hub; A wheel, which is rotatably mounted on the hub; An in-wheel electric motor, the in-wheel electric motor comprising a stator mounted on the hub and a rotor connected to the wheel, such that the rotor and the wheel rotate together with respect to the stator and the hub; and At least one wheel assembly bushing, the at least one wheel assembly bushing including an inner bushing member, an outer body, and an elastic sleeve, the outer body being concentrically arranged around the inner bushing member and radially spaced from the inner bushing member, the elastic sleeve being radially positioned between the inner bushing member and the outer body. The at least one wheel assembly bushing includes a hydraulic chamber and a helical fluid channel, the hydraulic chamber being positioned within the resilient sleeve, and the helical fluid channel extending helically around the inner bushing member between a first fluid channel end and a second fluid channel end arranged in fluid communication with opposite axial ends of the hydraulic chamber. The spiral fluid channel is configured as an inertial track, wherein fluid flow through the spiral fluid channel generates inertia within the bushing of at least one wheel assembly, the inertial operation being to reduce magnetic gap deformation between the stator and the rotor of the in-wheel motor.

2. The wheel assembly of claim 1, wherein the at least one wheel assembly bushing includes a separator and a fluid passage, the separator being within the resilient sleeve, the separator extending into the hydraulic chamber to divide the hydraulic chamber into a first hydraulic chamber segment and a second hydraulic chamber segment, the fluid passage causing hydraulic resistance and damping when fluid flows through the fluid passage between the first hydraulic chamber segment and the second hydraulic chamber segment.

3. The wheel assembly of claim 2, wherein the fluid passage is an annular opening that forms a pinch in the hydraulic chamber restricting fluid flow between the first hydraulic chamber segment and the second hydraulic chamber segment, such that the fluid passage and the helical fluid channel in the hydraulic chamber cooperate to produce a phase delay between an input force and a reaction force, the input force causing relative movement between the inner bushing member and the outer body, the reaction force being caused by a pressure pulse in the hydraulic chamber resulting from the fluid flow through the fluid passage and the helical fluid channel.

4. The wheel assembly of claim 1, wherein the hub includes an axle portion, and wherein the stator includes an inner portion and an outer portion, the inner portion extending annularly around and supported on the hub portion of the hub, and the outer portion extending annularly around and supported on the axle portion of the hub.

5. The wheel assembly of claim 4, wherein the at least one wheel assembly bushing includes a first wheel assembly bushing positioned between the hub and the stator, and wherein the hub portion of the hub is received within and adjacent to the inner bushing member of the first wheel assembly bushing, the outer body of the first wheel assembly bushing is received within and adjacent to the inner portion of the stator, and the resilient sleeve of the first wheel assembly bushing is radially positioned between the hub portion of the hub and the inner portion of the stator.

6. The wheel assembly of claim 4, wherein the at least one wheel assembly bushing includes a second wheel assembly bushing positioned between the hub and the stator, and wherein the axle portion of the hub is received within and abuts the inner bushing member of the second wheel assembly bushing, the outer body of the second wheel assembly bushing is received within and abuts the outer portion of the stator, and the resilient sleeve of the second wheel assembly bushing is radially positioned between the axle portion of the hub and the outer portion of the stator.

7. The wheel assembly of claim 1, wherein a plurality of wheel bolts connect the wheel to the rotor, and the at least one wheel assembly bushing includes a plurality of third wheel assembly bushings positioned between the wheel bolts and the wheel, wherein the wheel bolts are received within and abut against the inner bushing member of the third wheel assembly bushings, the outer body of the third wheel assembly bushings is received within and abut against the wheel, and the resilient sleeve of the third wheel assembly bushings is positioned between the wheel bolts and the wheel.

8. The wheel assembly of claim 1, wherein the at least one wheel assembly bushing includes a first wheel assembly bushing and a second wheel assembly bushing, the first wheel assembly bushing and the second wheel assembly bushing being radially positioned between the hub and the stator and positioned longitudinally spaced apart.

9. The wheel assembly of claim 1, wherein at least one wheel bolt connects the wheel to the rotor, and wherein the at least one wheel assembly bushing includes a first wheel assembly bushing positioned between the hub and the stator and a third wheel assembly bushing positioned between the wheel and the wheel bolt.

10. The wheel assembly of claim 1, wherein at least one wheel bolt connects the wheel to the rotor, and wherein the at least one wheel assembly bushing includes a second wheel assembly bushing positioned between the hub and the stator and a third wheel assembly bushing positioned between the wheel and the wheel bolt.

11. The wheel assembly of claim 1, wherein at least one wheel bolt connects the wheel to the rotor, and wherein the at least one wheel assembly bushing includes a first wheel assembly bushing and a second wheel assembly bushing positioned between the hub and the stator, and a third wheel assembly bushing positioned between the wheel and the wheel bolt.

12. The wheel assembly of claim 1, wherein the resilient sleeve is made of an elastic material such that the resilient sleeve is configured to allow relative movement between the inner bushing member and the outer body, and wherein the helical fluid channel is configured to produce a phase delay between an input force and a reaction force, the input force causing relative movement between the inner bushing member and the outer body, the reaction force being caused by pressure pulses in the hydraulic chamber caused by fluid flow through the helical fluid channel.

13. The wheel assembly of claim 1, further comprising: A brake caliper, the brake caliper being fixed to at least one of the wheel hub and the stator; and A brake disc, which is fixed to the rotor, such that the brake disc and the rotor rotate together relative to the brake caliper.

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