Claims:We Claim:
1. A pivot bush for a vehicle suspension unit, comprising:
a metal sleeve (102);
a rubber portion (101) surrounding the metal sleeve (102) for absorbing impact forces;
wherein the rubber portion (101) provided from a first end (103a) to a second end (103b) and from a top end (304a) to a bottom end (304b);
a first cavity (104a) and a second cavity (104b) provided at the first end (103a) and the second end (103b) for reducing stiffness;
the first cavity (104a) and the second cavity (104b) including a top edge (205a) and a bottom edge (205b) extending along an inner portion of the pivot bush forming an extended top edge (205aa) and an extended bottom edge (205bb);
characterized in that
an inclined surface (202a) formed on the extended top edge (205aa) of the first cavities (104a) inclined at an angle relative to the top surface (304a); and
an inclined surface (202b) formed on the extended top edge (205aa) of the second cavities (104b) inclined at an angle relative to the bottom surface (304b).
2. The pivot bush as claimed in claim 1, wherein the angle selected from a range of 0° to 5°.
3. The pivot bush as claimed in claim 1, wherein a profile of the first cavity (104a) and the second cavity (104b), including:
a circular segment (202a) provided at one end and another end;
a middle segment (202b) formed by the top edge 205a and the bottom edge 205b between the circular segments (202a); and
a radius of the circular segments selected from a range of 5mm to 15mm.
4. The pivot bush as claimed in claim 3, wherein a horizontal distance (203) of a center of the circular segment (202a) from a central vertical axis is selected from a range between 20mm to 50mm.
5. The pivot bush as claimed in claim 3, wherein a vertical distance (204) of a center of the circular segment (202a) from a central horizontal axis is selected from a range between 10mm to 50mm.
6. The pivot bush as claimed in claim 1, wherein the top edge (205a) forming an outer radius (206) of the first cavity and the second cavity (104a, 104b) and the outer radius (206) selected from a range of 50mm to 70mm; and
the bottom edge (205b) forming an inner radius (207) of the first cavity and the second cavity (104a, 104b) and the inner radius (207) selected from a range of 40mm to 60mm.
7. The pivot bush as claimed in claim 6, wherein a centre ‘C’ of the outer radius offset from a center ‘O’ of the pivot bush and a distance of the offset (209) selected from a range of 5mm to 20mm.
8. The pivot bush as claimed in claim 1, wherein a curved fillet (302) provided at an inner end connecting the extended top edge (205aa) and the extended bottom edge (205bb) and a radius of the curved fillet (302) selected from a range of 5mm to 10mm.
9. The pivot bush as claimed in claim 1, wherein a distance (208) between the top edge (205a) and the bottom edge (205b) is selected from a range of 5mm to 15mm.
10. The pivot bush as claimed in claim 1, wherein a fillet (210) is formed between the circular segment (202a) and the middle segment (202b) and a radius of the fillet (210) selected from a range of 1mm to 10 mm.
11. The pivot bush as claimed in claim 1, wherein a diameter of the rubber portion (101) in a free state is in a range of 150mm to 170mm; and
a diameter of the rubber portion (101) in a compressed state is in a range of 143mm to 150mm.
12. The pivot bush as claimed in claim 1, wherein a length (305) of the first cavity (104a) and the second cavity (104b) in a free-state selected from a range of 80mm to 90mm.
, Description:AN IMPROVED PIVOT BUSH FOR A VEHICLE SUSPENSION UNIT
FIELD
[0001] The embodiments herein generally relate to a pivot bush. More particularly, the disclosure relates to an improved pivot bush in an air suspension system of an automobile.
BACKGROUND AND PRIOR ART
[0002] A suspension system is provided in automobiles for improving ride handling and imparting comfort. The suspension system helps in maintaining contact between tires of a vehicle and the road surface and evenly balancing weight of the vehicle. Improper and uneven road conditions generate forces on the vehicle, and the effect of these forces are dampened and absorbed by components of the suspension system.
[0003] Generally, heavy commercial vehicles such as Buses, trucks, trailers use an air suspension system as it provides better support in variable road conditions. A pivot bush is a crucial component in the air suspension system. The pivot bush endures forces such as braking, driving, cornering and other factors and provides a cushioning effect for not transmitting the impact load to the structural components of the air suspension system.
[0004] Conventionally, the existing design of pivot bush includes cavities for reducing stiffness in a particular direction. However, the presence of cavities generates high stress concentration zones leading to reduced fatigue life of the pivot bush.
[0005] Therefore, there is a need for an improved pivot bush having less stress concentration and better fatigue life. Moreover, there is a need for an improved design of pivot bush for a vehicle air suspension unit.
OBJECTS
[0006] Some of the objects of the present disclosure are described herein below:
[0007] The main objective of the present disclosure is to provide an improved pivot bush for a vehicle suspension unit.
[0008] Another objective of the present disclosure is to provide a pivot bush with better fatigue life for an air suspension of an automobile.
[0009] Still another objective of the present disclosure is to provide a pivot bush with reduced stress concentration for an air suspension of an automobile.
[00010] Yet another objective of the present disclosure is to provide a pivot bush capable of withstanding and enduring impact forces for a longer duration of time.
[00011] The other objectives and advantages of the present disclosure will be apparent from the following description when read in conjunction with the accompanying drawings, which are incorporated for illustration of preferred embodiments of the present disclosure and are not intended to limit the scope thereof.
SUMMARY
[00012] In view of the foregoing, an embodiment herein provides a pivot bush for a vehicle suspension unit.
[00013] In accordance with an embodiment, the pivot bush comprises a metal sleeve, and a rubber portion surrounding the metal sleeve for absorbing impact forces, wherein the rubber portion provided from a first end to a second end and from a top end to a bottom end. A first cavity and second cavity is provided at the first end and the second end for reducing stiffness wherein the first cavity and the second cavity includes a top edge and a bottom edge extending along an inner portion of the pivot bush forming an extended top edge and an extended bottom edge. An inclined surface is formed on the extended top edge of the first cavities inclined at an angle relative to the top surface and an inclined surface is formed on the extended top edge of the second cavities inclined at an angle relative to the bottom surface. In an embodiment, the angle selected from a range of 0° to 5°.
[00014] In an embodiment, a profile of the first cavity and the second cavity, includes a circular segment provided at one end and another end, a middle segment formed by the top edge and the bottom edge between the circular segments and a radius of the circular segments selected from a range of 5mm to 15mm. In an embodiment, a horizontal distance of a center of the circular segment from a central vertical axis is selected from a range between 20mm to 50mm. In an embodiment, a vertical distance of a center of the circular segment from a central horizontal axis is selected from a range between 10mm to 50mm.
[00015] In accordance with an embodiment, the top edge forms an outer radius of the first cavity and the second cavity and the outer radius selected from a range of 50mm to 70mm and the bottom edge forms an inner radius of the first cavity and the second cavity and the inner radius selected from a range of 40mm to 60mm.
[00016] In an embodiment, centre C of the outer radius is offset from center O of the pivot bush and distance of the offset is selected from a range of 5mm to 20 mm.
[00017] In an embodiment, a curved fillet is provided at an inner end connecting the extended top edge and the extended bottom edge and a radius of the curved fillet is selected from a range of 5mm to 10mm.
[00018] In an embodiment, a distance between the top edge and the bottom edge is selected from a range of 5mm to 15mm.
[00019] In an embodiment, a fillet is formed between the circular segment and the middle segment and a radius of the fillet selected from a range of 1mm to 10 mm.
[00020] In an embodiment, a diameter of the rubber portion in a free state is in a range of 150mm to 170mm and a diameter of the rubber portion in a compressed state is in a range of 143mm to 150mm.
[00021] In an embodiment, a length of the first cavity and the second cavity in a free-state selected from a range of 80mm to 90mm.
[00022] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

BRIEF DESCRIPTION OF DRAWINGS
[00023] The detailed description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items.
[00024] Fig.1 illustrates a perspective view of a pivot bush for a vehicle suspension unit, according to an embodiment herein;
[00025] Fig. 2 illustrates a side view of the pivot bush in a free state, according to an embodiment herein; and
[00026] Fig. 3 illustrates a sectional view of the pivot bush in a compressed state, according to an embodiment herein.

LIST OF NUMERALS
101 - Rubber portion
102 - Metal sleeve
103a - First end
103b - Second end
104a - First cavity
104b - Second cavity
201 - Compressed diameter of rubber portion
202a - Circular segment
202b - Middle segment
203 - Horizontal distance
204 - Vertical distance
205a - Top edge
205aa - Extended Top edge
205b - Bottom edge
205bb - Extended Bottom edge
206 - Outer radius of cavity
207 - Inner radius of cavity
208 - Distance between top edge and bottom edge
209 - Offset
210 - Fillet
301 - Free Diameter of rubber portion
302 - Curved portion
303a - Inclined surface of first cavities
303b - Inclined surface of second cavities
304a - Top surface
304b - Bottom surface
305 - Length of cavity

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[00027] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[00028] As mentioned above, there is a need for an improved pivot bush having less stress concentration and better fatigue life. In particular, there is a need for an improved design of pivot bush for a vehicle air suspension unit. The embodiments herein achieve this by providing “An improved pivot bush for a vehicle suspension unit”. Referring now to the drawings, and more particularly to Fig.1 through Fig.3, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments.
[00029] Fig.1 illustrates a perspective view of a pivot bush for a vehicle suspension unit. In an embodiment, the pivot bush including a rubber portion 101 and a metal sleeve 102. In an embodiment, the metal sleeve 102 is a steel sleeve. The rubber portion 101 is provided surrounding the metal sleeve 102, wherein the rubber portion 101 is provided as a cushion for absorbing impact forces and preventing the transmittal of the forces to the vehicle suspension unit.
[00030] In an embodiment, the pivot bush 100 includes a first end 103a and a second end 103b. A first cavity 104a and a second cavity 104b are provided in the pivot bush 100 at the first end 103a and the second end 103b.
[00031] Fig. 2 illustrates a side view of the pivot bush, wherein the rubber portion is in a compressed state. Compressed state refers to the rubber portion being enclosed in a cylindrical casing. In an embodiment, a diameter 201 of the rubber portion 101 in a compressed state is in a range of 140mm to 153mm. In a preferred embodiment, the diameter 201 in the compressed state is in a range of 143mm to 150mm.
[00032] In an embodiment, a profile of the first cavity 104a and the second cavity 104b includes a circular segment 202a provided at one end, a circular segment 202a provided at another end and a middle segment 202b formed by the top edge 205a and the bottom edge 205b between the circular segments 202a. In an embodiment, the circular segment 202a including a radius selected from a range between 5mm to 15mm.
[00033] In an embodiment, a horizontal distance 203 of a center of the circular segment 202a from a central vertical axis is selected from a range between 15mm to 55mm, specifically between 20mm to 50mm.
[00034] In an embodiment, a vertical distance 204 of a center of the circular segment 202a from a central horizontal axis is selected from a range between 5mm to 55mm, specifically between 10mm to 50mm.
[00035] In an embodiment, the first cavity 104a and the second cavity 104b include a top edge 205a and a bottom edge 205b. The top edge 205a forming an outer radius 206 of the cavities (104a, 104b). In an embodiment, the outer radius 206 selected from a range of 50mm to 70mm. The bottom edge 205b forming an inner radius 207 of the cavities (104a, 104b). In an embodiment, the inner radius 207 selected from a range of 40mm to 60mm. In an embodiment, a distance 208 between the top edge 205a and the bottom edge 205b of the middle segment 202b is selected from a range of 5mm to 15mm.
[00036] In an embodiment, centre C of the outer radius is offset from center O of the pivot bush. A distance of the offset 209 is selected from a range of 5mm to 20 mm.
[00037] In an embodiment, the first cavity and the second cavity includes a fillet 210 formed between the circular segment 202a and the middle segment 202b including a radius selected from a range of 1mm to 10 mm.
[00038] Fig. 3 illustrates a sectional view of rubber portion of the pivot bush in a free state. Free-state refers to the rubber portion no being enclosed by the cylindrical casing. In an embodiment, a diameter 301 of the rubber portion 101 in a free state is selected from a range of 150mm to 170mm. In a preferred embodiment, the diameter 301 of the rubber portion 101 in the free-state is 160mm.
[00039] In an embodiment, the first cavities 104a are provided at the first end 103a and the second end 103b and the second cavities 104b are provided at the first end 103a and the second end 103b of the pivot bush. The top edge 205 and the bottom edge 205b extending through an inner portion of the pivot bush forming an extended top edge 205aa and an extended bottom edge 205bb. A curved fillet 302 is provided at an inner end connecting the extended top edge 205aa and the extended bottom edge 205bb. The curved fillet 302 includes a radius selected from a range of 3mm to 12mm. In a preferred embodiment, the radius of the curved fillet is selected from a range of 5mm to 10mm. The first cavities 104a and the second cavities 104b include a same shape and size and the first cavities and the second cavities 104b are symmetrical about a central vertical axis of the pivot bush.
[00040] In an embodiment, the first cavity 104a and the second cavity 104b including a length 305 selected from a range of 75mm to 95mm in free-state (non-compressed state). In a preferred embodiment, the length 305 selected from a range of 80mm to 90mm.
[00041] In an embodiment, the extended top edge 205aa of the first cavities 104a including an inclined surface 303a. The inclined surface 303a is inclined at an angle relative to a top surface 304a of the pivot bush. The extended top edge 205aa of the second cavities 104b including an inclined surface 303b, wherein the inclined surface 303b inclined at an angle relative to a bottom surface 304b of the pivot bush. In an embodiment, the angle selected from a range of 0 degrees to 7 degrees, specifically between 0 degrees to 5 degrees.
[00042] A main advantage of the present disclosure is that the pivot bush includes an improved design with better fatigue life.
[00043] Another advantage of the present disclosure is that the pivot bush provides an improved design reducing stress concentration.
[00044] Still another advantage of the present disclosure is that the pivot bush provides an improved design for withstanding forces and preventing transmittal of impact of the forces to the vehicle suspension unit.
[00045] Yet another advantage of the present disclosure is that the improved pivot bush is simpler and cost effective.
[00046] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.