WO2021161345A1

WO2021161345A1 - Torsional vibration damper

Info

Publication number: WO2021161345A1
Application number: PCT/IN2021/050139
Authority: WO
Inventors: H. J. Raja; S. R. Navale; R. S. Channapattan; A. L. Khule
Original assignee: Hodek Vibration Technologies Pvt. Ltd.
Priority date: 2020-02-14
Filing date: 2021-02-13
Publication date: 2021-08-19

Abstract

Disclosed is a torsional vibration damper (100) that comprises a hub (30) formed of a low density material and in a unique design to reduce the overall weight of a damper assembly. The torsional vibration damper (100) has a very low density as compared to casting and steel and hence the inertia of the hub (30) is reduced that intern improves the torsional vibration performance of an engine. Lower weight and inertia of the torsional vibration damper (100) improves the power to weight ratio and NVH performance of the engine. The overall cost of manufacturing of the torsional vibration damper (100) is lesser as compared to the existing hub part. Further, the hub manufacturing process according to the present invention requires lower machining allowances as compared to forged steel, casting and hence the raw input material weight is less.

Description

TORSIONAL VIBRATION DAMPER

Field of the invention: The present invention relates to dampers for passenger vehicle applications and more particularly, to a torsion vibration damper for an automotive engine.

Background of the invention: The torsional vibration is an angular vibration produced along the axis of rotation. This is more concerned in rotating shafts and couplings of the power transferring units. Normally, the torsional vibration is produced in the internal combustion engines based upon the thermodynamic cycle of the engine. In the four-stroke cycle, one stroke is power which gives energy and remaining three strokes requires energy. This variation in energy generates torsional vibrations. If these torsional vibrations are not controlled, it will lead to failure of the crankshaft as well as increased vibration on front accessory end drive (FEAD) components resulting into functional loss of component and rapid wear. The torsional vibration dampers are used in the engines to limit the engine torsional vibration within allowable value. This reduction in the amplitude of vibrations lowers the strength requirements of the crankshaft and hence lowers the weight of the crankshaft. The position of the torsional vibration damper in the engine is shown in figure 1. The vibration damper also helps to reduce the chances of breakage of the crankshaft as well as to absorb the vibrations of various other components of the internal combustion engine.

Commonly available torsional vibration damper construction includes a central rubber ring sandwiched between a hub and an inertia ring by compression or molding process to form a complete assembly of the damper as shown in figure 2. Generally, the inertia ring and the hub of the damper are manufactured from high density material like cast iron and steel.

Deficiencies/drawbacks in the existing art

In the existing technology, the hub part of the damper is manufactured with high density materials like casting or steel. Hence, the finished damper assembly will be heavier hence provide poor power to weight ratio of the engine.

Accordingly, there exists a need to provide a torsional vibration damper to limit the vibrations produced in a combustion engine in an allowable value.

Objects of the invention:

An object of the present invention is to withstand the torsional load and to improve the torsional vibration performance of an engine.

Another object of the present invention is to reduce the overall weight of a damper assembly.

Yet another object of the present invention is to reduce the manufacturing cost for a torsional vibration damper.

Summary of the invention:

Accordingly, the present invention provides a torsional vibration damper (hereinafter, “the damper”). The damper comprises an inertia ring, an elastic member and a hub. The elastic member is sandwiched between the inertia ring and the hub. Specifically, the inertia ring is made of metal and the elastic member is made of rubber. The hub is made of a low density material, particularly polyamide. The hub includes a plurality of ribs configured on a circumference thereof that helps to withstand the dynamic load from an engine. The hub is molded with a bush to form a complete hub part. The bush includes a plurality of holes provided thereon. The bush provides an interlocking arrangement such that the load gets distributed and taken by two flat surfaces of the bush, the plurality of ribs and also through the plurality of holes. Being made of a low density material and in a unique design, the hub of the damper reduces the overall weight of a damper assembly.

Brief description of the drawings:

The objects and advantages of the present invention will become apparent when the disclosure is read in conjunction with the following figures, wherein Figure 1 shows a schematic view of an engine locating the position of a torsional vibration damper, in accordance with the prior art;

Figure 2 shows a schematic view of a torsional vibration damper, in accordance with the prior art;

Figure 3 shows an isometric view of a torsional vibration damper, in accordance with the present invention;

Figure 4 shows a front view of the torsional vibration damper, in accordance with the present invention;

Figure 5 shows a cross sectional view of the torsional vibration damper of figure 4 along line A- A, in accordance with the present invention;

Figures 6a-6b show a bush of the torsional vibration damper, in accordance with the present invention; and Figure 7 shows a graphical representation of an engine speed vs. noise level, in accordance with the present invention.

Detailed description of the invention:

The foregoing objects of the invention are accomplished, and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiments. The present invention provides a torsional vibration damper that absorbs the engine torsional vibrations and presents improved NVH (Noise, vibration, and harshness) characteristics for an engine. The torsional vibration damper is provided with a hub formed of a low density material and in a unique design to reduce the overall weight of a damper assembly.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description and the table given below.

Table 1:

Referring to figures 3 to 6b, a torsional vibration damper (100) (hereinafter referred to as “the damper (100)”) in accordance with the present invention is shown. Specifically, the damper (100) is applicable for the automotive engines used for passenger vehicle application.

As shown in figures 3-5, the damper (100) comprises an inertia ring (10), an elastic member (20) and a hub (30). The inertia ring (10) and the elastic member (20) are assembled with the hub (30) as shown in figure 5. Preferably, the inertia ring (10) is made of metal and the elastic member (20) is made of rubber. However, it is understood here that the inertia ring (10) and the elastic member (20) may be made of any other suitable material in other alternative embodiments of the present invention.

The hub (30) includes a plurality of ribs (25) configured on a circumference thereof. The plurality of ribs (25) strengthens the hub (30) and also helps to withstand the dynamic load from the engine. In an embodiment, the hub (30) is made of a low density material like polyamide and is molded along with a bush (40) to form a complete hub part of the damper (100). The bush (40) includes a plurality of holes (35) provided thereon as shown in figure 6a. In an embodiment, the bush (40) is made of metal, preferably steel. However, it is understood here that the bush (40) may be made of any other suitable material in other alternative embodiments of the present invention. The bush (40) provides an interlocking arrangement such that the load gets distributed and taken by two flat surfaces (not numbered) of the bush (40), the plurality of ribs (25) and also through the plurality of holes (35) thereby improving the reliability of the hub (30).

In accordance with the present invention, the inner hub (30) of the damper (100) is manufactured from polyamide having a low density with unique designed structure geometry. This makes the damper (100) capable of withstanding the torsional load and to improve the torsional vibration performance of the engine. In one exemplary embodiment, the hub (30) made of polyamide has following properties:

1. Tensile modulus (Mpa) : 15000 - 15700

2. E-Modulus (Mpa) : 4300 - 4500 at 120 degC 3. Stress limit (Mpa) : 70-75 at 120 degC

4. Tensile stress at Break ( Mpa min) : 200 - 210

5. Tensile strain at Break (% min) : 2.5 - 3

6. Melting Temperature (°C) : 210-225

7. Density (gm/cc) : 1.6

However, it is understood here that the hub (30) may be made of any other material having different properties in other alternative embodiments of the present invention. Being made of a low density material and in a unique design, the hub (30) of the damper (100) reduces the overall weight of a damper assembly. Specifically, the damper (100) of the present invention has approximately 30% lesser weight than the existing dampers that advantageously improve the engine power to weight ratio. Further, the damper (100) is capable of providing better NVH (Noise, vibration, and harshness) characteristics to the engine. Figure 7 shows a graphical representation of comparison of an engine speed vs. noise level of the damper (100) indicated by blue color and existing damper indicated by green color. The better NVH characteristics is achieved as upon experiencing the vibrations and inertia mass, the elastic member (20) deforms by absorbing the vibration energy and converting it into heat energy. This provides sufficient damping to the engine crankshaft and driven components of the engine.

In accordance with the present invention, the structural integrity of the damper (100) is checked by a finite element analysis. Specifically, 3D finite element model is built by using .stp file. The mesh grading is done to create fine mesh in high stress zones and minimum element size of 0.4 mm is used in interested zone. Worst case loading conditions were considered that will be exerted onto the damper (100) and as per the results the maximum stress observed in the hub (30) are well within the allowable strength limit for the hub (30) material used and no signs of any concerns or failure mode observed.

Advantages of the invention:

1. The damper (100) has very low density as compared to casting and steel and hence the inertia of the hub (30) is reduced that intern improves the torsional vibration performance of the engine.

2. Lower weight and inertia of the damper (100) improves the power to weight ratio and NVH performance of the engine.

3. The overall cost of manufacturing of the damper (100) is lesser as compared to the existing hub part. Further, the hub manufacturing process according to the present invention requires lower machining allowances as compared to forged steel, casting and hence the raw input material weight is less.

4. The damper (100) reduces engine weight and fuel consumption as well as emission.

5. The damper (100) reduce industrial waste, as the plurality of ribs (25) is manufactured through molding process and hence no further machining is required on the component.

6. Ease in material recyclability. The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the scope of the present invention.

Claims

We claim:

1. A torsional vibration damper (100) comprising: an inertia ring (10); and an elastic member (20) sandwiched between the inertia ring (10) and a hub

(30), characterized in that , the hub (30) being made of a low density material having a plurality of ribs (25) configured on a circumference thereof that helps to withstand the dynamic load from an engine, and a bush (40) molded along with the hub (30) to form a complete hub part, the bush (40) having a plurality of holes (35) provided thereon, wherein, the bush (40) provides an interlocking arrangement such that the load gets distributed and taken by two flat surfaces of the bush (40), the plurality of ribs (25) and also through the plurality of holes (35).

2. The torsional vibration damper (100) as claimed in claim 1, wherein the hub (30) is made of polyamide.

3. The torsional vibration damper (100) as claimed in claim 1, wherein the inertia ring (10) and the bush (40) are made of metal.

4. The torsional vibration damper (100) as claimed in claim 1, wherein the elastic member (20) is made of rubber.