MXPA98007388A - Assembly of drive axis with ventilated structure of ru reduction - Google Patents

Abstract

The present invention relates to a drive shaft assembly for a vehicle drive train, comprising: a hollow drive shaft tube having a pair of ends and an inner surface, a first and second end fittings fixed to the ends of the drive shaft tube so as to define an inner chamber, at least one of the first and second end fittings have a ventilation opening formed therein, and a noise reduction element mounted under pressure within the shaft tube For defining a pair of interior subchambers therein, the noise reduction element is formed of a material that is substantially impermeable to the passage of fluid therethrough and has formed a conduit to provide fluid communication between the vent opening and each of the inner sub-chambers inside the motor shaft tube

Description

ASSEMBLY OF THE MOTOR SHAFT PON VENTILATED STRUCTURE OF NOISE REDUCTION AN? (J DENTS OF THE INVENTION This invention relates in general to noise reduction structures for use in vehicle drive shaft assemblies. In particular, this invention relates to an improved noise reduction structure having a conduit or other opening formed therein to provide ventilation between a vent opening formed between an end fitting secured to one end of a drive shaft tube. , and inner chambers defined within the drive shaft tube when the noise reduction structure is placed therein. Axes transmitting torque are widely used to transfer rotational power between a rotational power source and a rotationally driven mechanism. An example of a torque moment transmission axle is a drive axle tube used in a vehicle drive axle assembly. The drive shaft assembly transmits rotational power from a source, such as a motor, to a driven component, such as a pair of wheels. A typical vehicle drive shaft assembly includes a hollow cylindrical drive shaft tube having an end fitting secured to each end thereof. Usually, the end fittings are constituted as forks which are adapted to cooperate with respective universal joints. For example, a drive shaft assembly of this general type is often used to provide a rotatable drive connection between the secondary drive shaft of a vehicle and a drive shaft of a shaft assembly to rotationally drive the wheels of a vehicle. . Traditionally, drive shaft tubes are made of steel. More recently, aluminum drive shafts have been developed due to their lighter weight. A problem encountered with all types of drive shaft assemblies is their tendency to produce and transmit sound while transferring motor power to the tree assembly. It is known that any mechanical body has a natural resonant frequency. This natural resonant frequency is an inherent characteristic of the mechanical body and is based on many factors including its composition, size and shape. The natural resonant frequency is made up of many sub frequencies, often referred to as harmonics. As the vehicle is operated through its normal speed range (ie, from 0 km / h to approximately 129 km / h (0-80 mph)), the rotational speed of the drive shaft assembly (ie, from 0 rpm to approximately 5,000 rpm). As the rotational speed of the drive shaft changes, it passes through harmonic frequencies of the resonant frequency of the body. When the rotational speed of the drive shaft passes through these harmonic frequencies, vibration and noise are amplified since the two frequencies are synchronized and the rotational energy of the drive shaft becomes vibration and noise. Noise may be undesirable for passengers in the vehicle. Therefore, it would be advantageous to dampen or reduce the sound produced by a vehicle drive axle assembly in order to provide passengers with a quieter and more comfortable ride. Various attempts have been made to dampen the sound produced by the vehicle drive shaft tubes. A general direction that many attempts have followed is to place a noise absorption / damping structure within the drive shaft. For example, an attempt involves placing a hollow cylindrical cardboard insert inside the aluminum drive shaft tube to dampen the sound. However, the cardboard insert requires external rubber rims to prevent it from sliding inside the aluminum drive shaft tube. As a result, the cardboard insert is relatively complicated and expensive to use. It is also known to place a solid structure of noise reduction within the drive shaft tube to absorb noise and vibration. A typical noise reduction structure is a generally cylindrical member having a predetermined length which is placed within a drive shaft tube in a relationship placed under pressure with the inner surface of the drive shaft tube. Typically, the noise reduction structure is placed inside the drive shaft tube at a position where the amplitude of a standing wave caused by reflection of sound waves back and forth along the drive shaft tube is found with its maximum value. If more than one noise reduction structure is placed therein, the first noise reduction structure is located some distance in from one end of the drive shaft tube, and the remaining noise reduction structures are then they separate, typically at equal intervals. As previously noted, the typical drive shaft assembly further includes an end fitting secured to each end of the drive shaft tube. In any hollow drive shaft assembly, air can be trapped within its internal space when two end fittings are attached to the hollow drive shaft tube. In the past, this space was ventilated by forming a vent hole in one of the two end fittings secured to opposite ends of the drive shaft tube. The ventilation opening prevents an undesirable vacuum or pressure from occurring inside the drive shaft tube. However, the use of one or more solid noise reduction structures within the drive shaft tube prevents part of the internal spaces from being vented through the vent opening. If a noise reduction structure is placed inside a drive shaft tube, the interior of the drive shaft tube is divided into two chambers, one of which is ventilated and one of which is not. Similarly, if multiple noise reduction structures are placed therein, the interior of the drive shaft tube is divided into several chambers, with only one of these chambers ventilated. Although a vent can be formed through each of the end fittings, it is preferable to avoid the time and expense involved in such an additional manufacturing step. In addition, this stage would not completely ventilate the interior of the drive shaft tube if two or more noise reduction structures are placed therein. Therefore, it would be desirable to provide an improved noise reduction structure which ensures that each of the inner chambers of the drive shaft tube is properly ventilated during use.

BRIEF DESCRIPTION OF THE INVENTION The invention relates to a noise reduction structure for use in a vehicle drive shaft assembly which ensures that each of the inner chambers of a driving shaft tube is properly ventilated during use. The noise reduction structure is a solid member having a predetermined cross sectional length and shape which generally corresponds to the cross-sectional shape of the drive shaft tube. Preferably, the noise reduction structure has an outer diameter which is approximately equal to, or slightly larger than, the inner diameter of the drive shaft tube. As such, the noise reduction structure makes contact with the inner surface of the drive shaft tube in a light pressure positioning relationship. Each noise reduction structure has a duct, slot or other opening formed therein which extends axially through its length. In a preferred embodiment, a groove is formed that extends axially on the outer circumferential surface of the noise reduction structure. át ^ 10 The slot provides free air flow from one end to the other of the noise reduction structure, thereby ensuring that each of the inner chambers of the drive shaft tube is adequately ventilated during use. Various objects and advantages of this invention will become apparent to those familiar with the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic elevation view of a drive train of a prior art vehicle including a drive line assembly. Fig. 2 is a side view, partly in cross section and partly in schematic view of the drive line assembly of the prior art illustrated in Fig. 1. Fig. 3 is a side view, partly in cross section and partly in view schematic, of a drive line assembly having a noise reduction structure positioned within the drive shaft tube, according to this invention. Figure 4 is a schematic perspective view of one of the noise reduction structures illustrated in Figure 3.

DESCRIPTION DETAT.T,? T > ? ? TZ THE PREFERRED MODALITY Now with reference to the drawings, there is illustrated in FIG. 1 a vehicle drive train, indicated generally with the number 10, according to this invention. The drive train system 10 includes a clutch / transmission assembly 12 which is connected to the shaft assembly 14 through a drive line assembly 15. The drive line assembly 15 includes a hollow cylindrical drive shaft tube 16 which is connected between a secondary shaft (not shown) of the clutch / transmission assembly 12 and a drive shaft (not shown) of the shaft assembly 14 for a pair of 18 universal joints. As is typical in vehicle drive train systems of this type, the secondary shaft of the clutch / transmission assembly 12 and the drive shaft of the shaft assembly 14 are not coaxially aligned. Universal joints 18 are provided at each end 20 of the drive shaft tube 16 to rotatably connect the drive shaft tube 16 to the secondary shaft of the clutch / transmission assembly 12 and to the drive shaft of the shaft assembly 14, while allowing a limited amount of lack of alignment of the rotational axes of the same. The connection between the ends 20 of the drive shaft tube 16 and the universal joints 22 is usually carried out by tube anvils 22. Figure 2 illustrates the structure of the assembly 15 of the drive line in detail. As shown therein, the drive shaft tube 16 is an elongated hollow cylindrical tube having an axial length L defined by the distance between the two ends 20 thereof. The drive shaft tube 16 includes an inner cylindrical surface 24 extending therealong and defining an internal diameter D. The drive shaft tube 16 can be formed from a single piece of metal. Alternatively, multiple pieces of drive shaft tube can be used. In addition, the drive shaft 16 can be formed with a central portion of larger diameter, and the end portion having a reduced diameter, and a portion of reduced diameter positioned between the central and end portions. This type of drive shaft tube is more fully described in the commonly owned US patent of the assignee number 5,643,093, issued July 1, 1997, the disclosure of which is incorporated herein by reference. The drive shaft tube 16 can be formed of any suitable material. Typically, the drive shaft tube 16 is formed of steel or an aluminum alloy. Preferably, the drive shaft tube 16 is formed of an aluminum alloy. Suitable methods for forming the drive shaft tube 16 are well known to those familiar with the art. The ends 20 of the drive shaft tube 16 are open and adapted to receive an end fitting 22. In the illustrated embodiment, the tube anvil 22 is positioned within each end 20. In general, each tube anvil 22 typically includes a tube housing 26 at one end and a nose structure 28 at the other end. The tube housing 26 is generally a cylindrical member which is adapted to be inserted into an open end of the drive shaft tube 16. Accordingly, the tube housing 26 allows twisting motion to be transmitted between the drive shaft tube 16 and the tube fork 22. Typically, the tube fork 22 is fixed to the drive shaft tube 16 by a weld. In the illustrated embodiment, a circular weld 30 is made around the circumference of the interface between the drive shaft tube 16 and the tube yoke 22. Once assembled, the tube forks 22 and the inner surface 24 of the drive shaft tube 16 define a closed inner chamber 27. In order to prevent air trapped within the inner chamber 27 from generating an undesirable vacuum or pressurization condition within the drive shaft tube 16, a vent opening 22a is formed in at least one of the tube forks 22 . The vent opening 22a provides fluid communication between the inner chamber 27 and the atmosphere, whereby the vacuum or pressurization condition within the drive shaft tube 16 is prevented. The protrusion structure 28 of each tube fork 22 is operatively connected to a cross 31 used in each universal joint 18. Each universal joint 18 also includes a second fork 32 or 34, as shown in Figure 2. Each fork 32 and 34 is operatively connected to a connecting shaft 36 and 37, respectively. One of these connection axes 36 may be connected to the transmission 12, while the other connection axis 37 may be connected to the shaft assembly 14. In the illustrated embodiment, the fork 32 is a sliding fork having internal grooves 38 which cooperate with external grooves 40 in the connecting shaft 36 to allow the fork 32 and the connecting shaft 36 to move axially one with respect to the other. Now with reference to Figure 3, a drive line assembly 15 'according to this invention is illustrated. In general, the drive line assembly 15 'includes all of the components described above. Therefore, the description of these components and the numbers used to identify these components are applicable to the description of the drive line assembly 15 '. However, the drive line assembly 15 'in accordance with this invention has improved sound deadening properties to reduce noise and vibration of the drive shaft tube during vehicle operation. The invention obtains this benefit by placing one or more noise reduction structures 50 within the drive shaft tube 16. It may be desirable to provide various noise reduction structures 50 at separate positions within the drive shaft tube 16 to resolve the vibration and noise generated by the secondaries of the harmonics of the resonant frequency. It has been found that it is desirable to form noise reduction structures 50 of a polyether material having a density of at least 0.022 g / cm3 (1.4 pounds / cubic foot), and more desirably it is formed having a density of 0.024 g / cm3 (1.5 pounds / cubic foot). In a drive shaft tube 16 having a length of about 1473 mm (58 inches) to about 1778 mm (70 inches), it has been found desirable to pressurize a single elongated noise reduction structure 50 therein that forms of polyether material. The noise reduction structure 50 preferably has a length of about 1016 mm (40 inches) and is centered within the axial length of the drive shaft tube 16. Alternatively, a plurality of separate noise reduction structures 50 can be provided within the drive shaft tube 16. It has been found desirable to pressurize four such noise reduction structures 50 formed from the polyether material into the drive shaft tube 16. Each of these noise reduction structures is preferably approximately 203 mm (8 inches) in length and spaced equidistantly from one another symmetrically within the drive shaft tube 16. However, the size and quantity of such noise reduction structures 50, as well as the material 10 used thereon may vary as desired. In Figure 4 one of the noise reduction structures 50 is illustrated in detail. As shown here, the noise reduction structure 50 is a generally cylindrical member having an axial length Ll extending from a first end 51 to a second end 52. The noise reduction structure 50 also includes an outer cylindrical surface defining an outer diameter DI. Preferably, the outer diameter DI of the noise reduction structure 50 is slightly larger than the inner diameter D of the axle tube 16 motor. When the outer diameter DI is slightly larger than the inner diameter D, the noise reduction structure 50 can be placed under pressure within the drive shaft tube 16. When the noise reduction structure 50 is pressed into the drive shaft tube 16, it is not necessary to use a adhesive to retain the structure 50 in place.

Alternatively, any suitable adhesive can be used to retain the noise reduction structure 50 within the drive shaft tube 16. For example, in a drive shaft tube 16 having an inner diameter D of about 127 mm (5.0 inches), the noise reduction structure 50 can have an outer diameter of about 129.9 mm (5,115 inches), to about 130.4 mm (5,135 inches). When one or more of the noise reduction structures 50 is placed within the drive shaft tube 16, as shown in Figure 3, a plurality of interior sub-chambers are defined (such as those shown with numbers 27a, 27b and 27c). in Figure 3) inside the drive shaft tube 16. As shown in Figure 3, only the first sub-chamber 27a is in direct fluid communication with the ventilation opening 22a formed through the fork 22 of the tube. In order to ventilate the remaining sub-chambers 27b and 27c to the atmosphere, each of the structures 50 of noise reduction of this invention has a conduit 53 formed therethrough. In the preferred embodiment of the invention illustrated in Figure 4, the conduit 53 is a semicircular, linear groove formed in the outer cylindrical surface of the noise reduction structure 50 extending between the first and second ends 51 and 52 of the same. However, the conduit 53 does not need to extend linearly and can be formed to have any desired cross-sectional shape. Alternatively, the conduit 53 may be partially or completely formed within the noise reduction structure 50, instead of being on the outer surface thereof, as illustrated. In addition, a plurality (not shown) of such conduits 53 can be formed in each of the noise reduction structures 50. The conduits 53 can be linearly aligned within the drive shaft tube 16, as shown in Fig. 4. However, such linear alignment is not necessary. The conduit 53 provides free air flow from the first end 51 of the noise reduction structure 50 to the second end 52 thereof. As a result, each of the inner sub-chambers 27b and 27c of the drive shaft tube 16 is suitably ventilated through the vent hole 22a to the atmosphere. In this way, the entire drive shaft assembly 15 'is ventilated, whereby an undesirable pressurization or vacuum condition is prevented from occurring therein. In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention has been explained and illustrated in its preferred embodiment. However, it should be understood that this invention can be appreciated in another way to that explained and illustrated specifically, without departing from its spirit or scope.

Claims (8)

1. A drive shaft assembly for a vehicle drive train, characterized in that it comprises: a hollow drive shaft tube having a pair of ends and an inner surface; first and second end fittings fixed to the ends of the drive shaft tube so as to define an inner chamber, at least one of the first and second end fittings have a vent opening formed therein; and a noise reduction structure positioned within the drive shaft tube to define a pair of inner subchambers therein, the noise reduction structure has a conduit formed therein to provide fluid communication between the ventilation aperture and each of the inner sub-chambers inside the drive shaft tube.

2. The drive shaft assembly, according to claim 1, characterized in that the noise reduction structure is placed under pressure within the drive shaft tube.

3. The drive shaft assembly, according to claim 1, characterized in that the noise reduction structure includes an outer surface, and wherein the conduit is a groove formed in the outer surface.

4. The drive shaft assembly, according to claim 3, characterized in that the conduit has a semicircular cross-sectional shape.

5. The drive shaft assembly, according to claim 1, characterized in that the noise reduction structure extends from a first end to a second end, and wherein the conduit extends from the first end to the second end.

6. The drive shaft assembly, according to claim 1, characterized in that a plurality of noise reduction structures are placed within the drive shaft tube, each of the noise reduction structures has a conduit formed therein.

7. The drive shaft assembly, according to claim 1, characterized in that the noise reduction structure is formed from a polyether material having a density of at least 0.022 g / cm3 (1.4 pounds / cubic foot).

8. The drive shaft assembly, according to claim 7, characterized in that the polyether material has a density of 0.024 g / cm3 (1.5 pounds / cubic foot).