AN ELASTIC DAMPER
FIELD OF THE INVENTION
[0001] The present invention relates generally to an elastic damper and
more particularly, but not exclusively, to an elastic damper for mounting of an internal combustion engine.
BACKGROUND OF THE INVENTION
[0002] In many countries of the world, motor vehicle particularly a three
wheeled automotive vehicle is a significant mode of public transportation. It is vastly used as a point to point mode of transport in rural and urban areas. Though such vehicle is designed to bear the load of four people, generally it is overloaded and is operated intermittently for 12 to 14 hours a day to enable the driver to maximize his earnings.
[0003] Generally, the three wheeled automotive vehicle is powered by an
internal combustion engine. The engine is mounted within a rear compartment at a lower posterior portion of the vehicle conventionally in the form of a two-front and one-rear fashion on a frame assembly of the vehicle, i.e., as a dual point front mount and single point rear mount.
[0004] Such three wheeled vehicle is often driven over pot holed roads in
urban areas and on rugged, rough, unmetalled roads in rural areas. Due to operating on this type of terrain along with carrying excess load, the engine is subjected to a lot of bending stress. Additionally, the operation of engine itself
produces vibrations which may be transferred to the vehicle frame. To reduce the transfer of engine vibrations and to support the engine on the vehicle frame, an elastic damper assembly is provided between the engine and the vehicle frame. The damper in the damper assembly is of resilient type. It is designed to absorb shear stresses. However, it may also absorb compressive and tensile stresses. The damper absorbs the engine load during static loading and transfers a portion of such load to the vehicle frame during operational loading.
[0005] When the vehicle is in motion, the damper experiences radial load
due to rocking motion and pitching motion of the engine which is passed on to the damper through a spacer. The spacer passes through, and maintains a clearance with, an annular opening provided in the damper. In ideal conditions, the spacer should be co-axial with the damper longitudinal axis. However, many a times due to fabrication inconsistencies in the vehicle frame, it is difficult to maintain this co-axiality. Consequently, during radial loading one end of the spacer slaps an inner radial surface of the annular opening which is stiff.
[0006] Another situation is possible where the extent of loading is huge
particularly when the vehicle travels along very bumpy roads, for example, rugged, rough, unmetalled roads. During vehicle operation in this condition, one end of the spacer slaps an inner radial surface of the annular opening.
SUMMARY OF THE INVENTION
[0007] To prevent the radial load from being transferred to the vehicle
frame, the area of the damper slapped by the spacer should be less stiff. However,
the damper is made of elastic materal like rubber and has a uniform stiffness throughout. Therefore, a need exists to locally reduce the shear stiffness of the damper without affecting its durability.
[0008] It is therefore an object of the present invention to provide an
elastic damper having a locally reduced shear stiffness than currently available dampers.
[0009] It is another object of the present invention to locally reduce the
shear stiffness of the damper without affecting its durability.
[00010] The present invention thereofore discloses an elastic damper
comprising an upper portion, a base portion, an upper annular opening provided in the upper portion, a lower annular opening provided in the base portion, a spacer passing through the. upper annular opening and the lower annular opening along the long axis of the elastic damper; wherein the base portion further comprises of a plurality of apertures. The apertures are disposed radially outwardly around the lower annular opening in a circular fashion. Further, each aperture from the plurality of apertures is spaced from the adjacent aperture.
[00011] A one end of each aperture opening toward the base portion and a
one other end opening toward the upper portion define a groove, wherein the groove is parallel to a longitudinal axis of the elastic damper. The apertures, owing to the defined grooves, create a space around the lower annular opening. Thus, the shear stiffness of the elastic material immediately coming in contact
with the spacer is locally reduced. The locally less stiff damper then absorbs the load rather than failing.
[00012] The foregoing objectives and summary is provided to introduce a
selection of concepts in a simplified form, and is not limiting. To fully appreciate these and other objects of the present subject matter as well as the subject matter itself, all of which will become apparent to those skilled in the art, the ensuing detailed description of the subject matter and the claims should be read in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
[00013] The above and other features, aspects and advantages of the subject
matter will be better understood with regard to the following description, appended claims and accompanying drawings where:
[00014] FIG. 1 shows a side view of a three wheeled automotive vehicle
according to the present subject matter.
[00015] FIG. 2 shows a rear view of the three wheeled automotive vehicle
of FIG. 1.
[00016] FIG. 3 shows a top view of a vehicle frame of the three wheeled
automotive vehicle.
[00017] FIG. 4(a) and 4(b) respectively show an exploded view of
mounting of an internal combustion engine on the vehicle frame.
[00018] FIG. 5 shows a perspective view of an elastic damper .
[00019] FIG. 6(a) shows a bottom view of the elastic damper illustrating a
base portion according to a first embodiment of the present invention.
[00020] FIG. 6(b) shows a sectional view of the elastic damper according to
the first embodiment of the present invention.
[00021] FIG. 7(a) shows a sectional view of the elastic damper assembly
according to the first embodiment of the present invention.
[00022] FIG. 7(b) shows an exploded view of the elastic damper assembly
according to the first embodiment of the present invention.
[00023] FIG. 8(a) shows a perspective view of the damper according to a
second embodiment of the present invention.
[00024] FIG. 8(b) shows a bottom view of the elastic damper illustrating
the base portion according to the second embodiment of the present invention.
[00025] FIG. 9(a) shows a sectional view of the elastic damper assembly
according to the second embodiment of the present invention.
[00026] FIG. 9(b) shows an exploded view of the elastic damper assembly
according to the second embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[00027] The subject matter disclosed herein relates to an elastic damper
used to mount an internal combustion engine on a vehicle frame in a three wheeled automotive vehicle. The three wheeled automotive vehicle is mainly, but not solely, used as a passenger carrier. It is to be noted that "front" and "rear", and "left" and "right" wherever referred to in the ensuing description, refer to front and rear, and left and right directions as seen in a state of being seated on a seat of
the vehicle and looking forward. Furthermore, a longitudinal axis refers to a front to rear axis relative to the vehicle, while a lateral axis refers generally to a side to side, or left to right axis relative to the vehicle. Various other features of the elastic damper according to the present subject matter here will be discernible from the following further description thereof, set out hereunder.
[00028] FIG. 1 illustrates a side view of a concerned three wheeled
passenger carrier vehicle, referenced by the numeral 100, driven by an internal combustion engine. The vehicle can be used as a passenger carrier vehicle or a load carrier vehicle. It has a front cowl 101 supporting a windscreen 102. The lower portion of the front cowl 101 is connected to a front wheel 104 with a wheel cover 103 disposed in between. A handle bar assembly 109 is present behind the front cowl 101 which is used to operate the said three wheeled vehicle 100. In this view, a steering tube assembly 202 is not visible to an onlooker of the vehicle. The vehicle is longitudinally divided into two halves along the line X-Y; an anterior portion A having a driver's seat 107 while a posterior portion P having a long passenger seat 108 with a seating capacity of minimum three passengers. A rear panel (also known as rear compartment or rear cabin) 106 along with the posterior portion P of the vehicle containing the passenger seat 108 is supported on a pair of rear wheels 105 located on either side of the longitudinal axis of the vehicle 100.
[00029] The rear compartment 106 houses an internal combustion engine
400 and other vehicular components. FIG. 2 shows a rear view of the said three wheeled vehicle 100 showing the otherwise invisible internal combustion engine
400 and other vehicular components like induction system, exhaust system, transmission system etc. mounted on the posterior side of the vehicle frame within the rear compartment 106. In an embodiment, the engine is a diesel driven internal combustion engine. The internal combustion engine 400 produces the necessary power which is then transferred to the transmission through a clutch.
[00030] FIG. 3 shows a top view of a frame of the vehicle 100. At its rear
portion, the vehicle comprises of a plurality of long members attached to the main front frame for carrying the vehicle load. The long members are extended rearwardly along the vehicle longitudinal axis to accommodate updated vehicular components including a diesel driven internal combustion engine. A first long member 120 is provided at a left side whereas a second long member 130 is provided at the right side of the vehicle frame. The first long member 120 is spaced laterally from the second long member 130 in a vehicle width direction. The long members are connected by a tower 110 extending in the vehicle width direction (FIG. 2) and projecting vertically upwards. The rear compartment 106 is supported on the long members 120, 130 through the tower 110. The long members are further connected in vehicle width direction through the suspension cross member 140 which connects a rear suspension of the vehicle to the vehicle frame. In an embodiment, the suspension cross member 140 is supported on a middle portion of the first long member 120 and the second long member 130 through welding.
[00031J The engine 400 is mounted on the vehicle frame in a non-cradle
type arrangement through a plurality of elastic dampers in a two front mount and
one rear mount fashion as explained in FIG 4(a) and 4(b). The engine 400 is mounted on the vehicle using a front cross member 170 for supporting a front portion of the engine 400 and a rear cross member ISO for supporting the rear portion of the engine 400. The front cross member 170 and the rear cross member
180 are at a lower elevation than the suspension cross member 140. In an
embodiment, the front cross member 170 is a long rod extending in vehicle width
direction.
[00032] In an embodiment, the front cross member 170 has two ends, a first
end 171 and a second end 172. The first end 171 of the front cross member 170 is secured to a first elastic damper 13 whereas the second end 172 is secured to a second elastic damper 162.
[00033] The rear cross member 180 is supported on each of the first long
member 120 and second long member 130 at a rear end. A third elastic damper
181 is connected to one side of the rear cross member 180. The rear portion of the
engine is supported on the rear cross member 180 through a rear engine mounting
bracket 182 which is further bolted to the third elastic damper 181.
[00034] In an embodiment, the first elastic damper 13, the second elastic
damper 162 and the third elastic damper 181 are identical in construction and preferably made of rubber or any other elastic material. They take the load of the engine and also damp the engine vibrations. Due to identical construction, only one of the elastic dampers is explained according to the present subject matter.
[00035] FIG. 5 shows a perspective view of the first elastic damper 13
(henceforth called elastic damper). The elastic damper 13 comprises of an upper portion 14 and a base portion 15. In an embodiment, the upper portion 14 is conical in shape and the base portion 15 is wider and circular. FIG. 6(b) shows a sectional view of the elastic damper 13. The upper portion 14 has an upper annular opening 20 and the base portion 15 has a lower annular opening 16. The lower annular opening 16 defines an inner radial surface 17. The upper annular opening 20 is co-axial to the lower annular opening 16. The conical upper portion 14 of the damper has a hollow portion 10 inside. The cross section of the hollow portion 10 depends upon the load bearing capacity of the elastic damper.
[00036] The base portion 15 of the elastic damper 13 also comprises a
plurality of apertures 18 disposed radially outwardly around the lower annular opening 16 in a circular fashion. Each aperture from the plurality of apertures 18 is spaced from the adjacent aperture. Each pair of spaced apertures defines a radial arm between them which connects an inner circumferential surface around the lower annular opening 16 to an outer circumferential surface of the base portion 15. FIG. 6(a) shows a bottom view of the elastic damper 13 illustrating the base portion 15 according to a first embodiment of the present invention in which each aperture 18 has a cylindrical cross section with a circle visible when seen from the bottom view. A one end of each aperture 18 opens towards the base portion 15 whereas a one other end of the aperture opens toward the hollow portion 10 thus defining a groove 19 therebetween. In an embodiment, the groove 19 is parallel to
a longitudinal axis of the elastic damper 13. In another embodiment, the length of the groove is proportional to the cross section of the elastic damper.
[00037] FIG. 7(a) shows a sectional view of the assembly of the elastic
damper according to the first embodiment of the present invention. A top plate 12
is mounted on the upper portion 14 of the damper 13 which connects the damper
13 to an engine mounting bracket. A bottom plate 22 is mounted below the base
portion 15 which connects the elastic damper to the frame mounting bracket (not
shown). The bottom plate 22 provides a seat for the elastic damper 13. A fastener
(hex bolt) 11 passing through the upper annular opening 20 and lower annular
opening 16 connects the top plate 12 and the bottom plate 22 and secures the
damper 13 to the vehicle frame and the engine. The fastener 11 is secured through
a washer 23 and a nut 24. The nut 24 and the fastener 11 connect the damper
relative to the engine mounting bracket or the frame mounting bracket.
[00038] A spacer 21 passes through the upper annular opening 20 and
lower annular opening 16 along the long axis of the damper 13 and is located radially outwardly of the fastener 11 and inwardly of the annular openings. In an embodiment, the spacer 21 is a bush. The spacer 21 maintains a clearance with an inner radial surface 17 of the damper 13. FIG. 7(b) shows an exploded view of the elastic damper assembly according to the first embodiment of the present invention.
[00039] According to a second embodiment, the aperture 18 has a kidney
shaped cross section as shown in FIG. 8(a) to 9(b) forming a periphery radially of the lower annular opening 16. Other details remain same as that of the first
embodiment. Meanwhile, the depth of the aperture is 18 dependent on the cross section of the elastic damper 13. In a preferred embodiment, the groove 19 of aperture 18 has a length in the range of 3 mm to 8 mm from the base portion 15.
[00040] The working of the elastic damper 13 is now explained. During the
radial loading of the damper on rocking or pitching motion of the engine 400, a lower endportion of the spacer 21 slaps the inner radial surface 17 of the damper 13. The shear stresses concentrate around the inner radial surface 17. More particularly, the shear stresses may mount to very high levels during operation of the vehicle on bumpy roads. However due to the presence of a plurality of apertures 18 defining the grooves 19, the stiffness of the adjacent elastic material reduces thus enabling the damper 13 to locally absorb the load in the area of contact. The elastic damper offers greater absorption of the shear stresses and enables reduces transfer of vibrations to the vehicle frame. The shear stiffness of the elastic material, which comes in contact with the spacer 21, is locally reduced. Also, reduction in shear stiffness results in higher isolation of longitudinal and lateral forces thereby improving the vibration absorbing characteristics of the elastic damper.
[00041] The elastic damper is preferably made of rubber and is used for
engine mounting in a three wheeled vehicle. It may also be used for other vehicle configurations beyond the three wheeler application. The vehicle may have several such elastic dampers. The elastic damper may also be mounted in the reverse orientation wherein the base portion would be upward and upper portion would be downwardly mounted. The elastic damper is preferably conical in shape,
however the subject matter disclosed in the present invention is also applicable on dampers of other shapes including rectangular or spherical dampers.
[00042] The present subject matter is thus described. The description is not
intended to be exhaustive nor is it intended to limit the invention to the precise form disclosed. It will be apparent to those skilled in the art that the disclosed embodiments may be modified in light of the above description. The embodiments described are chosen to provide an illustration of principles of the invention and its practical application to enable thereby one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore the forgoing description is to be considered exemplary, rather than limiting, and the true scope of the invention is that described in the appended claims.
We claim:
1. An elastic damper (13) comprising:
an upper portion (14) having an upper annular opening (20);
a base portion (15) having a lower annular opening (16), the lower annular opening (16) being co-axial to the upper annular opening (20);
a spacer (21) passing through the upper annular opening (20) and the lower annular opening (16) along the long axis of the elastic damper (13);
wherein,
the base portion (15) further comprises of a plurality of apertures (18) disposed radially outwardly around the lower annular opening (16) in a circular fashion, and wherein each aperture from the plurality of apertures (18) is spaced from the adjacent aperture.
The elastic damper as claimed in claim 1, wherein a one end of each aperture (18) opening toward the base portion (15) and a one other end opening toward a hollow portion (10) define a groove (19).
The elastic damper as claimed in claim 2, wherein the groove (19) is parallel to a longitudinal axis of the elastic damper (13).
The elastic damper as claimed in claim 2, wherein the length of the each groove (19) is proportional to the cross section of the elastic damper (13).
The elastic damper as claimed in claim 1, wherein the upper portion (14) of the elastic damper (13) is conical in shape and the base portion (15) is circular in shape.
The elastic damper as claimed in claim 1, wherein each aperture (18) has a cylindrical cross section.
The elastic damper as claimed in claim 1, wherein each aperture (18) has a kidney shaped cross section.
The elastic damper as claimed in claim 1, wherein the elastic damper (13) is made of an elastic material including rubber.
A three wheeled vehicle comprising at least one elastic damper (13) as claimed in any of the preceding claims wherein the at least one elastic damper is sandwiched between an engine and a vehicle frame.