Hydraulic bushing with internal stroke limiter

Abstract

A hydraulic bushing assembly includes an inner tube, a stroke limiter surrounding the inner tube, a first intermediate insert, a second intermediate insert spaced apart from the first intermediate insert, and an elastomeric bushing disposed around the inner tube and enclosing the first and second intermediate inserts. The elastomeric bushing at least partially encloses the stroke limiter such that a portion of the elastomeric bushing is positioned between the stroke limiter and the inner tube. A first buffer block and a second buffer block limit displacement of the stroke limiter and define a first fluid chamber and a second fluid chamber within the elastomeric bushing. A fluid passage defined by the elastomeric bushing and an outer tube extends between the first and second fluid chambers, wherein relative movement between the inner and outer tubes causes fluid transfer between the first and second fluid chambers.

Description

Technical Field

[0001] This disclosure relates to a hydraulic bushing. More specifically, the present invention relates to a hydraulic bushing having an integrally formed internal stroke limiter. Background Technology

[0002] The statements in this section provide only background information in connection with this disclosure and may not constitute prior art.

[0003] Hydraulic bushings, commonly used in automotive suspensions, are intended to suppress low-frequency, large-displacement oscillations and help isolate high-frequency sound from relatively small displacements. Hydraulic bushings typically have two hydraulic chambers connected by a channel. Resonance of the fluid in the channel produces a mass damper effect. Some designs employ flexible travel limiters to improve bushing durability by transferring high loads from the inner tube to the outer tube via the travel limiter rather than the elastomeric bushing.

[0004] Integrating flexible travel limiters into high-load-bearing hydraulic bushing applications presents challenges. Traditionally, flexible travel limiter constructions involve chemically bonding a rubber pad to an internal component that transfers loads to an external component. Durability can be a concern due to the limited abrasion resistance of the rubber pad, as it needs to account for combined loads (e.g., torsional angles with radial loads). Known travel limiter designs may tend to generate higher tensile stresses on the surface, potentially increasing the likelihood of travel limiter tearing. Summary of the Invention

[0005] The hydraulic bushing assembly includes: an inner tube including an outer surface; an outer tube surrounding the inner tube; a stroke limiter spaced apart from and surrounding the inner tube; and an elastomeric bushing coupled to the outer surface of the inner tube and at least partially enclosing the stroke limiter. A portion of the elastomeric bushing is positioned between the stroke limiter and the outer surface of the inner tube. This portion of the elastomeric bushing is compressible to allow relative movement between the inner tube and the stroke limiter. A buffer block is positioned within the outer tube and spaced apart from the stroke limiter in an unloaded state. When loaded, the stroke limiter is operable to move to contact the buffer block. A fluid passage defined by the elastomeric bushing and the outer tube fluidly interconnects a first fluid chamber and a second fluid chamber. Movement of the inner tube relative to the outer tube results in fluid transfer between the first and second fluid chambers.

[0006] In another arrangement, the hydraulic bushing assembly includes an inner tube, a stroke limiter surrounding the inner tube, a first intermediate insert, a second intermediate insert spaced apart from the first intermediate insert, and an elastomeric bushing disposed around the inner tube and enclosing the first and second intermediate inserts. The elastomeric bushing at least partially encloses the stroke limiter such that a portion of the elastomeric bushing is positioned between the stroke limiter and the inner tube. A first and second buffer block limit the displacement of the stroke limiter and define a first and a second fluid chamber within the elastomeric bushing. A fluid passage defined by the outer tube and the elastomeric bushing extends between the first and second fluid chambers, wherein relative movement between the inner and outer tubes causes fluid transfer between the first and second fluid chambers.

[0007] Further applicability will become apparent from the description provided herein. It should be understood that the descriptions and specific examples are for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0008] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way.

[0009] Figure 1 This is a perspective view of a hydraulic bushing assembly according to one embodiment of the present disclosure;

[0010] Figure 2 yes Figure 1 A cross-sectional view of the hydraulic bushing assembly shown;

[0011] Figure 3 yes Figure 1 A cross-sectional view of the hydraulic bushing assembly shown;

[0012] Figure 4 yes Figure 1 A partial perspective view of the hydraulic bushing assembly shown;

[0013] Figure 5 yes Figure 1 A cross-sectional view of the hydraulic bushing assembly shown; and

[0014] Figure 6 yes Figure 1 A partial perspective view of the hydraulic bushing assembly shown. Detailed Implementation

[0015] Exemplary embodiments will now be described in more detail with reference to the accompanying drawings.

[0016] 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.

[0017] 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.

[0018] When an element or layer is referred to as “on,” “joined to,” “connected to,” or “linked to” another element or layer, the element or layer may be directly on, joined to, connected to, or linked 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 linked 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.

[0019] 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.

[0020] 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.

[0021] Figures 1 to 6 A hydraulic bushing assembly, generally indicated by reference numeral 10, is shown. The hydraulic bushing assembly 10 includes an inner tube 12, an elastomer bushing 16, a first intermediate insert 20, a second intermediate insert 24, a first buffer block 28, a second buffer block 32, a stroke limiter 36, and an outer tube 40.

[0022] The inner tube 12 is preferably a metal component made of mild steel such as SAE J403 1008-1010. The inner tube 12 includes through holes 44 for receiving fasteners (not shown) to interconnect the hydraulic bushing assembly 10 to vehicle components such as suspension control arms. A plurality of circumferentially spaced ventral members 48 extend from either end of the inner tube 12. The ventral members 48 may cooperate with adjacent components to which the hydraulic bushing assembly 10 is coupled to aid in alignment and maintaining the rotational position of the inner tube 12. Since some portions of the inner tube 12 may be exposed to the environment, the outer surface of the inner tube 12 may be treated with a Zn-Ni plating.

[0023] The first intermediate insert 20 and the second intermediate insert 24 are identical to each other. Therefore, only the first intermediate insert 20 will be described in detail. Similar features on the second intermediate insert 24 will be identified by the suffix "a". The first intermediate insert 20 includes an annular body 52 having a cylindrical outer surface 56, an inner surface 60, an outer end face 64, and an inner end face 68. The first intermediate insert 20 and the second intermediate insert 24 are made of a plastic material (such as nylon PA6), which can be reinforced and specified to be filled with 35% glass.

[0024] Channel 72 extends circumferentially along the cylindrical outer surface 56 over a large portion of the circumferential range of body 52. ​​Channel 72 includes a first axial extension 76 that extends to an inner end face 68 to define a first port 80. Channel 72 includes a second axial extension 84 that extends to the inner end face 68 to define a second port 88. A pair of diameter-opposite tabs 92, 96 extend axially from the inner end face 68. A plurality of grooves 100 extend axially from the outer end face 64 into body 52. ​​As will be described in more detail, each of the first intermediate insert 20 and the second intermediate insert 24 is completely encapsulated within an elastomeric bushing 16. During overmolding, molten elastomeric material fills the grooves 100 to enhance structural interconnection and maintain the desired relative position between other overmolded components and the elastomeric bushing 16.

[0025] The second intermediate insert 24 is positioned in a mirror orientation opposite to that of the first intermediate insert 20, such that tabs 92 and 92a are axially aligned with each other. Tabs 96 and 96a are also axially aligned with each other.

[0026] The stroke limiter 36 includes a body 104 having a cylindrical through-hole defined by an inner surface 110. The outer surface 112 is substantially spherical. A pair of diameter-opposite protrusions 116, 120 extend radially outward from the outer surface 112. Each protrusion 116, 120 includes spherical contact surfaces 124, 128, respectively. The stroke limiter 36 may be formed of a plastic material similar to or different from the material used to construct the first intermediate insert 20 and the second intermediate insert 24. In this example, the stroke limiter 36 is also constructed of 35% glass-filled nylon PA6.

[0027] In an exemplary method of manufacturing the hydraulic bushing assembly 10, each of the inner tube 12, the first intermediate insert 20, the second intermediate insert 24, and the stroke limiter 36 is placed in an injection mold in a spaced-apart relationship. A liquid elastomer is injected into the mold to bond each of the previously listed components to one another. Once cured, the elastomer bushing 16 includes a cylindrical inner portion 134 bonded to the outer surface 138 of the inner tube. The inner portion 134 is also bonded to the inner surface 110 of the stroke limiter 36 to provide an elastomer pad between the stroke limiter 36 and the inner tube 12, allowing relative movement between the stroke limiter 36 and the inner tube 12 to occur during high-load conditions.

[0028] The elastomeric bushing 16 also includes a first flange 142 and a second flange 146, which are integrally formed with and extend radially outward from the inner portion 134. A first web 150 and a second web 154 extend longitudinally to interconnect the first flange 142 and the second flange 146. Each of the first web 150 and the second web 154 extends radially outward from the inner portion 134. The first flange 142, the second flange 146, the inner portion 134, and the first web 150 and the second web 154 cooperate with each other to define a first cavity 160 and a diametrically opposed second cavity 164.

[0029] The first flange 142 includes a circumferentially extending channel 168 that extends over a large portion of the circumference of the first flange 142. The channel 168 includes a first axially extending portion 172 that defines a first port 176 communicating with a first cavity 160. The channel 168 includes a second axially extending portion 180 that defines a port 184 in fluid communication with a second cavity 164. When the hydraulic bushing assembly 10 is fully assembled, the first cavity 160 and the second cavity 164 cooperate with the first buffer block 28 and the second buffer block 32 to define a first fluid chamber 188 and a second fluid chamber 190.

[0030] The second flange 146 is essentially a mirror image of the first flange 142 and includes a channel 194. The channel 194 extends circumferentially to define a third port 198 in fluid communication with the first chamber 188 and a fourth port 202 in fluid communication with the second fluid chamber 190. Channel 168 provides fluid communication between the first chamber 188 and the second chamber 190 via the first port 176 and the second port 184. Based on the described fluid path and the non-rigid nature of the elastomeric bushing 16, fluid flows between the first chamber 188 and the second chamber 190 during relative movement between the inner tube 12 and the outer tube 40. The fluid flow between the fluid chambers 188 and 190 through channels 168 and 194 creates a mass damper effect within the hydraulic bushing assembly 10.

[0031] like Figure 1As best shown, the elastomeric bushing 16 may also include radially outwardly extending ribs 206. The ribs 206 are diametrically opposed and positioned at an angular orientation associated with the rotational positions of the first web 150 and the second web 154. The ribs 206 provide a visual indication of the component positions once the components within the hydraulic bushing assembly 10 have been fully constructed. The ribs 206 may cooperate with mating features in adjacent vehicle components to correctly align the travel limiter 36 relative to the direction of the intended maximum load.

[0032] The first buffer block 28 and the second buffer block 32, even if not identical, are substantially similar to each other. Therefore, only the first buffer block 28 will be described in detail. Similar elements will be identified with the same reference numerals. The first buffer block 28 is substantially semi-circular, having a curved wall 210 with an outer surface 214 and an inner surface 218. A protrusion 222 extends radially inward from the inner surface 218. A spherical stop surface 226 extends circumferentially along the inner radial range of the protrusion 222. Figure 5 As best shown, the contact surfaces 124, 128 of the travel limiter 36 are radially spaced stop surfaces 226. These figures illustrate the travel limiter 36 partially embedded within, but not completely enclosed in, the elastomer bushing 16. The elastomer material does not cover the distal ends of the protrusions 116, 120. This condition allows direct contact between the spherical surfaces 124, 128 and the stop surfaces 226 during high load conditions. It should be understood that while this exposed surface configuration may be preferred, it is also conceivable that the travel limiter 36 is completely enclosed within the elastomer bushing 16. In this configuration, the relatively thin thickness of the elastomer bushing 16 is positioned radially outward of the protrusions 116, 120.

[0033] Each of the first buffer block 28 and the second buffer block 32 includes a fan-shaped notch 230 through which fluid flows during fluid transfer between the first fluid chamber 188 and the second fluid chamber 190. A groove 234 is formed at one end of each of the first buffer block 28 and the second buffer block 32 for engagement with a corresponding portion of the elastomer bushing 16 to properly align the first buffer block 28 and the second buffer block 32 within the first cavity 160 and the second cavity 164, respectively.

[0034] The elastomeric bushing 16 includes a plurality of flanges 238 extending circumferentially around its outer surface, the shape and size of which are designed to sealably engage within the inner surface 242 of the outer tube 40 and fully define fluid passages including channels 168, 194. Axially extending flanges 246 project radially outward from the first web 150 and the second web 154 to sealably engage the inner surface 242 of the outer tube 40 and define fluid chambers 188, 190.

[0035] Before positioning the outer tube onto the elastomeric bushing 16, all components are immersed in fluid. Once immersed, the first buffer block 28 is positioned within the first cavity 160 and the second buffer block 32 is positioned within the second cavity 164 to define and fill chambers 188, 190 with fluid. The outer tube 40 is then axially translated over the elastomeric bushing 16 and the buffer blocks 28, 32 and press-fitted with them. The distal end 250 of the outer tube 40 is mechanically coiled or otherwise deflected to maintain the desired relative axial position of the outer tube 40 with respect to the elastomeric bushing 16. Chambers 188, 190 may be filled with any suitable liquid, such as water or ethylene glycol.

[0036] Of particular advantage, the elastomer bushing 16 includes portions that are radially inwardly positioned from the travel limiter 36 and other portions that are radially outwardly positioned from the travel limiter 36. Figure 5 A cross-sectional view is provided, showing the two protrusions 116, 120 spaced apart from the corresponding first buffer block 28 and second buffer block 32 when the hydraulic bushing assembly 10 is in an unloaded state. When installed in a running vehicle, a force F can be applied to the inner tube 12, causing the inner tube 12 and the protrusions 120 to face towards... Figure 5 The rightward displacement is shown until the spherical surface 128 contacts the stop surface 226. At this time, portion A of the first flange 142 and portion B of the second flange 146 are in a compressed state. As described below, portion C of the first flange 142 opposite to portion A is in a tensioned state. Portion D of the second flange 146, located on the same side of the inner tube 12 as portion C, is also in a tensioned state. The volume E of the inner portion 134 is also in a compressed state. At this time, the stroke limiter 36 can no longer shift toward the buffer block 32.

[0037] The additional relative movement between the inner tube 12 and the outer tube 40 is provided by the compressibility of the inner portion 134. Since the stroke limiter 36 stops moving, any strain acting on portions C and D will not increase or will only increase minimally during the final stage of the movement of the inner tube 12 relative to the outer tube 40, while the stroke limiter 36 engages one of the buffer blocks 28, 32. The disclosed hydraulic bushing assembly 10 offers advantages over previous designs that do not limit tensile stress in portions C and D as previously described.

[0038] The above description of the embodiments has been provided for illustrative and descriptive purposes. It is not intended to be exhaustive or limiting of this disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment; however, where applicable, they may be interchanged and used in the chosen embodiment, even if not specifically shown or described. The same may also apply in many other respects. Such variations should not be considered as departing from this disclosure, and all such modifications are intended to be included within the scope of this disclosure.

Claims

1. A hydraulic bushing assembly, the hydraulic bushing assembly comprising: Inner tube, the inner tube including an outer surface; Outer tube, which surrounds the inner tube; A travel limiter, the travel limiter being spaced apart from and surrounding the inner tube; An elastomeric bushing is coupled to the outer surface of the inner tube and at least partially encloses the travel limiter, wherein a portion of the elastomeric bushing is positioned between the travel limiter and the outer surface of the inner tube, and the portion of the elastomeric bushing is compressible to allow relative movement between the inner tube and the travel limiter. A buffer block, positioned inside the outer tube and spaced apart from the travel limiter when unloaded, wherein the travel limiter is operable to move to contact the buffer block when loaded; First fluid chamber and second fluid chamber; A fluid passage located between the elastomer bushing and the outer tube, extending between a first fluid chamber and a second fluid chamber, wherein movement of the inner tube relative to the outer tube causes fluid transport between the first and second fluid chambers; and A first intermediate insert and a second intermediate insert spaced apart from the first intermediate insert, the elastomeric bushing enclosing the first intermediate insert and the second intermediate insert, wherein the first intermediate insert includes a groove defining a path for the fluid passage.

2. The hydraulic bushing assembly of claim 1, wherein the stroke limiter includes a protrusion having a distal surface.

3. The hydraulic bushing assembly according to any one of claims 1-2, wherein the buffer block includes a stop surface that is selectively engaged with the distal surface of the travel limiter.

4. The hydraulic bushing assembly of claim 3, wherein the stop surface and the distal surface of the travel limiter are spherical.

5. The hydraulic bushing assembly of claim 2, wherein the inner tube extends along a longitudinal axis and the protrusion extends radially in one of the fluid chambers.

6. The hydraulic bushing assembly of claim 3, wherein the stop surface is positioned to maintain constant contact with fluid in one of the first fluid chamber and the second fluid chamber.

7. The hydraulic bushing assembly of claim 1, wherein the outer tube includes at least one coiled end.

8. The hydraulic bushing assembly of claim 1, wherein the elastomeric bushing includes axially spaced flanges interconnected by axially extending webs, wherein each web is part of each of a first fluid chamber and a second fluid chamber.

Images