Bearing bushing with integrated insulated insert for improved high-frequency insulation performance.

Abstract

Bearing bushing (10) which includes: an annular outer ring (12) designed for connection with a bearing structure; an annular bushing insert (14) which is arranged inside the outer ring (12); an annular main elastomer insulation arrangement (16) arranged between the outer ring (12) and the bushing insert (14), wherein the main elastomer insulation arrangement (16) is a double insulation arrangement comprising an annular mass element (17) located radially between an inner and an outer elastomer material; an annular secondary elastomer element (18) within the bushing insert (14), wherein the secondary elastomer element (18) is isolated from the main elastomer isolation arrangement (16) by the bushing insert (14); an annular structural insert (20) within the secondary elastomeric element (18); and a fastening screw which is inserted through a hole into the structural insert (20); wherein the outer elastomer material is a single annular elastomer material body which: - surrounds the ring-shaped mass element (17); - has two first annular segment-shaped slots, characterized by a first radius, which are offset from each other by 180° in the circumferential direction and which are formed as recesses along the inner circumference of the annular elastomeric material body; and - has two second annular segment-shaped slots, characterized by a second radius larger than the first radius, offset from each other by 180° in the circumferential direction, having a greater arc length than the first annular segment-shaped slots, and having an angular offset of 90° relative to the first annular segment-shaped slots.

Description

INTRODUCTION

[0001] The present invention relates to a bearing bushing with an integrated insulated insert for improved high-frequency insulation performance.

[0002] A conventional bearing bushing is described, for example, in FR 2 812 242 A1. This bearing bushing comprises an outer ring designed for connection with a bearing structure; a bushing insert arranged within the outer ring; a main elastomeric insulation arrangement positioned between the outer ring and the bushing insert, wherein the main elastomeric insulation arrangement is a double insulation arrangement having an annular bulk element located radially between an inner and an outer elastomeric material; a secondary elastomeric element within the bushing insert, wherein the secondary elastomeric element is isolated from the main elastomeric insulation element by the bushing insert; a structural insert within the secondary elastomeric element; and a fastening screw inserted through a bore in the structural insert.

[0003] Bearing bushings also emerge from the printed documents JP H02- 212 638 A, JP H08- 177 918 A and DE 31 13 049 A1.

[0004] Further details of the state of the art can be found in US 2006 / 0 202 400 A1.

[0005] Electric vehicle drive units exhibit a source energy with predominant frequencies up to 3000 Hz. Drive bearings and a supporting structure must provide sufficient insulation for this extended frequency range.

[0006] Structural components of the bearing assembly or drive unit often exhibit resonances in the 300-2000 Hz frequency range, necessitating an additional tuned vibration absorber (TVA) with significant additional mass, cost, and packing space to mitigate these resonances. Additionally, the drive unit motor may exhibit source energy with certain vibration orders, requiring improved isolation in the bearings. SUMMARY

[0007] According to the invention, a bearing bushing is presented which is characterized by the features of claim 1.

[0008] Further areas of application of the present invention will become apparent from the detailed description, the claims, and the drawings. The detailed description and the specific examples are for illustrative purposes only. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present invention will be more fully understood from the detailed description and the accompanying drawings; these show: Fig. 1 a longitudinal sectional view of a bearing bushing according to the principles of the present invention; Fig. 2 a cross-sectional view of the bearing bushing according to the principles of the present invention; Fig. 3a a schematic representation of a single isolation storage unit with the integrated isolated insert contrary to the principles of the present disclosure; Fig. 3b a schematic representation of a double insulation bearing with the integrated insulated insert according to the principles of the present invention; Fig. 3c a schematic representation of a load-decoupled double insulation bearing with the integrated insulated insert contrary to the principles of the present invention; and Fig. 4 a graphical representation of the ratio of the transmitted force as a function of the frequency for exemplary bearing bushings according to the principles of the present invention.

[0010] Reference symbols can be used multiple times in the drawings to identify similar and / or identical elements. DETAILED DESCRIPTION

[0011] Based on the attached drawings, exemplary embodiments will now be described in more detail.

[0012] In Fig. 1 and Fig. Figure 2 shows a longitudinal and a cross-sectional view of an exemplary bearing bushing 10 according to the principles of the present invention. The bearing bushing 10 is designed for improved isolation of high-frequency vibrations in a bearing structure for an electric vehicle drive unit, although the bearing bushing 10 could be used in other applications. The bearing bushing 10 includes an outer ring 12, which is received in or formed integrally as part of a bearing structure designed to be connected to an electric motor. A tubular bushing insert 14 is arranged inside the outer ring 12. A main elastomer isolation arrangement 16 is arranged between the outer ring 12 and the tubular bushing insert 14.The main elastomer insulation arrangement 16 includes a mass element 17 which is supported by inner and outer rubber or by other elastomeric material to provide a double insulation arrangement based on . Fig. 3b is described in more detail. A secondary elastomer element 18 is arranged within the tubular bushing insert 14, and a structural tube 20 is arranged within the secondary elastomer element 18. A fastening screw (not shown) is inserted through the structural tube 20 to fasten the structural tube 20 of the bearing bushing 10 to a frame or chassis of a vehicle. The structural tube 20 and the tubular bushing insert 14 can have cylindrical or other shaped cross-sections.

[0013] The length, thickness (general shape), and material of the secondary elastomer element 18 can be selected to provide a bearing resonance at a specified frequency, thereby achieving desired isolation from higher-frequency vibrations. According to an exemplary embodiment, the secondary elastomer element 18 can be made of natural rubber (NR), high-damping NR, synthetic rubber, silicone, or similar elastomers suitable for vibration isolation applications, and can have an outer diameter of less than 35 mm and an inner diameter of at least 23.5 mm (for an M12 screw and 19 mm for a 3 mm steel tube).

[0014] The bearing bushing 10 of the present invention incorporates integrated design features that improve high-frequency isolation with respect to resonance modes of the bearing support structure components (holders) and / or general excitation energy from the drive unit. The bearing bushing 10 utilizes the mass and structure of the bushing to generate a mass damping effect for high-frequency isolation without adding significant additional mass or occupying additional packing space. With minor modifications to the internal components of the bushing, the concept can be used with any type of bushing design. The improved bearing bushing design 10 incorporates a structural tube 20 and a secondary layer of elastomeric material 18, which is embedded in the inner bushing insert 14 of the main rubber element 16. The insulated structural tube 20 also acts as a support for the bushing assembly 10 on the bearing structure (vehicle frame or vehicle chassis).The mass of the components of the bushing arrangement 10, which are attached to the insulated structural tube 20 and to the outer ring 12, acts as a mass damper tuned to the specific frequency to reduce the vibration associated with the excitation energy.

[0015] Based on Fig. 3a-3c, the main elastomer insulation arrangement can assume 16 different forms and, for example, one as in Fig. 3a shown non-inventional single insulation arrangement, one as in Fig. 3b shown in the invention as a double insulation arrangement and one as shown in Fig. Figure 3c shows a load-decoupled double insulation arrangement not according to the invention. These are simplified one-dimensional representations of actual bearings, which are otherwise three-dimensional and show these properties in three orthogonal directions. The springs and dampers are condensed parameters of physical components of the bearing for mathematical characterization. A single spring or damper can represent the function of several physical components of the bearing, acting individually or together.

[0016] According to a model as in Fig. 3a shown non-inventional single insulation arrangement 16a are subjected to external forces (F excThe forces exerted on the mass (m) of the drive unit supported by the bearing bushing 10a (as part of a bearing system with multiple bushings) are transmitted to the tubular bushing insert 14a by a single spring and damper arrangement k, c in the form of an elastomeric material such as rubber. According to the principles of the present invention, the secondary elastomeric element 18 is designed to provide high-frequency vibration isolation between the tubular bushing insert 14 and the structural tube 20. The secondary elastomeric element 18 can be made of rubber or another elastomeric material. The secondary elastomeric element 18 is isolated from the main elastomeric isolation element 16 by the tubular bushing insert 14a.

[0017] In a situation like in Fig. In the double insulation arrangement 16b shown in 3b according to the invention, external forces (F excThe forces exerted on the mass (m) of the drive unit supported by the bearing bushing 10b (as part of a bearing system with multiple bushings) are transmitted to the tubular bushing insert 14b by a pair of spring and damper elements k1, c1; k2, c2, each in the form of an elastomeric material such as rubber and an intermediate mass element 17. According to the principles of the present invention, the secondary elastomeric element 18 is designed to provide high-frequency vibration isolation between the tubular bushing insert 14b and the structural tube 20. The secondary elastomeric element 18 can be made of rubber or another elastomeric material. The second secondary elastomeric element 18 is isolated from the main elastomeric isolation element 16 by the tubular bushing insert 14b.

[0018] In a situation like in Fig. In the non-inventive load-decoupled double insulation arrangement 16c shown in 3c, external forces (F excThe forces exerted on the mass (m) of the drive unit supported by the bearing bushing 10c (as part of a bearing system with multiple bushings) are transmitted to the tubular bushing insert 14c by both a single spring and damper assembly k, c and a pair of spring and damper elements k1, c1; k2, c2, each in the form of an elastomeric material such as rubber and an intermediate mass element 17. According to the principles of the present invention, the secondary elastomeric element 18 is designed to provide high-frequency vibration isolation between the tubular bushing insert 14c and the structural tube 20. The secondary elastomeric element 18 can be made of rubber or another elastomeric material. The secondary elastomeric element 18 is isolated from the main elastomeric isolation element 16 by the tubular bushing insert 14c.

[0019] In Fig.Figure 4 shows a force transmission graph illustrating the improved high-frequency insulation of the integrated insulating bushing insert 14 and the secondary elastomeric element 18. Specifically, the solid line and the dashed lines represent the force transmission capability of a load-decoupled double insulation arrangement, while the dashed line represents the force transmission capability of a load-decoupled double insulation arrangement combined with the integrated insulating bushing insert 14 and the secondary elastomeric element 18. According to this example, the integrated insulating bushing insert 14 and the secondary elastomeric element 18 according to the present invention exhibit reduced force transmission capability in frequency ranges above 900 Hz compared to the load-decoupled double insulation arrangement alone.

Claims

[1] Bearing bush (10) comprising: an annular outer ring (12) designed for connection with a bearing structure; an annular bushing insert (14) which is arranged inside the outer ring (12); an annular main elastomer insulation arrangement (16) arranged between the outer ring (12) and the bushing insert (14), wherein the main elastomer insulation arrangement (16) is a double insulation arrangement comprising an annular mass element (17) located radially between an inner and an outer elastomer material; an annular secondary elastomer element (18) within the bushing insert (14), wherein the secondary elastomer element (18) is isolated from the main elastomer isolation arrangement (16) by the bushing insert (14); an annular structural insert (20) within the secondary elastomeric element (18); and a fastening screw which is inserted through a hole into the structural insert (20); wherein the outer elastomer material is a single annular elastomer material body which: - surrounds the ring-shaped mass element (17); - has two first annular segment-shaped slots, characterized by a first radius, which are offset from each other by 180° in the circumferential direction and which are formed as recesses along the inner circumference of the annular elastomeric material body; and - has two second annular segment-shaped slots, characterized by a second radius larger than the first radius, offset from each other by 180° in the circumferential direction, having a greater arc length than the first annular segment-shaped slots, and having an angular offset of 90° relative to the first annular segment-shaped slots. [2] Bearing bushing (10) according to claim 1, wherein the secondary elastomer element (18) is made of natural rubber NR, high damping NR, synthetic rubber, silicone or similar elastomers suitable for vibration isolation. [3] Bearing bushing (10) according to claim 1, wherein the secondary elastomer element (18) has an outer diameter of less than 35 mm.

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