Damped propshaft assembly and tuned damper for a damped propshaft assembly

Abstract

A damped propshaft assembly with a hollow shaft and a tuned damper, which is received in the hollow shaft and includes a liner and a damping member. The liner's mass and stiffness are tuned to attenuate one or more of a bending mode vibration and a torsion mode vibration that occurs at a first predetermined frequency. The liner is not configured to substantially damp shell mode vibration that occurs at a frequency that is not equal to the first predetermined frequency. The damping member is coupled to the liner and is configured to primarily attenuate shell mode vibration in the hollow shaft at one or more desired frequencies. The tuned damper attenuates the at least one of the bending moment vibration and the torsion mode vibration at the first predetermined frequency and also attenuates shell mode vibration. A method for forming a damped propshaft assembly is also provided.

Claims

1. A damped propshaft assembly comprising: a hollow shaft; and a pair of tuned dampers received in the hollow shaft, each of the tuned dampers having a liner and a damping member, each of the liners comprising a tubular structure, which does not contact the hollow shaft, and at least one resilient member that is affixed to the tubular structure and contacts an interior surface of the hollow shaft, each of the liners having a mass and a stiffness that are tuned to attenuate one or more of a bending mode vibration and a torsion mode vibration that occurs at a first predetermined frequency, each of the liners not being configured to substantially damp shell mode vibration that occurs at a frequency that is not equal to the first predetermined frequency, each of the damping members being coupled to an associated one of the liners, each of the damping members being configured to primarily attenuate the shell mode vibration in the hollow shaft at one or more desired frequencies; wherein the tuned dampers attenuate the at least one of the bending mode vibration and the torsion mode vibration at the first predetermined frequency and also attenuates the shell mode vibration.

2. The damped propshaft assembly of claim 1, wherein the liners are not configured to substantially damp the shell mode vibration occurring at a frequency that is less than or equal to 1000 Hz.

3. The damped propshaft assembly of claim 1, wherein the damping members provide broadband damping.

4. The damped propshaft assembly of claim 3, wherein the broadband damping includes damping of the shell mode vibration and damping of bending mode vibration at a plurality of frequencies.

5. The damped propshaft assembly of claim 3, wherein each of the damping members is a resistive absorber.

6. The damped propshaft assembly of claim 3, wherein each of the liners is configured to contact an inside surface of the hollow shaft over a first area, wherein each of the damping members is configured to contact the inside surface of the hollow shaft over a second area, and wherein a ratio of the first area to the second area is less than or equal to five (5) percent.

7. The damped propshaft assembly of claim 6, wherein the ratio of the first area to the second area is less than or equal to two and one-half (2.5) percent.

8. The damped propshaft assembly of claim 7, wherein the ratio of the first area to the second area is less than or equal to one and one-quarter (1.25) percent.

9. The damped propshaft assembly of claim 3, wherein each of the damping members includes at least one contact member that is configured to contact an inside surface of the hollow shaft and wherein each of the damping members has a durometer of between 40 Shore A and 80 Shore A.

10. The damped propshaft assembly of claim 1, wherein each of the liners is disposed symmetrically about a bending anti-node.

11. The damped propshaft assembly of claim 10, wherein the bending anti-node is a second bending anti-node.

12. The damped propshaft assembly of claim 1, wherein each of the tubular structures is formed of cardboard.

13. A tuned damper for damping a propshaft assembly, the propshaft assembly including a hollow shaft with an inside diametrical surface, the tuned damper comprising: a liner having a tubular structure and at least one resilient member, the tubular structure having a diameter that is smaller than the inside diametrical surface so that the tubular structure does not touch the inside diametrical surface when the tuned damper is received into the hollow shaft, the at least one resilient member being affixed to the tubular structure and configured to contact the inside diametrical surface of the hollow shaft, the liner having a mass and a stiffness that are tuned to attenuate one or more of a bending mode vibration and a torsion mode vibration that occurs at a first predetermined frequency, the liner itself not being configured to substantially damp shell mode vibration that occurs at a frequency that is not equal to the first predetermined frequency, a damping member coupled to the liner, the damping member being configured to primarily attenuate the shell mode vibration in the hollow shaft at one or more desired frequencies; wherein the tuned damper is configured to attenuate the at least one of the bending mode vibration and the torsion mode vibration at the first predetermined frequency and is also configured to attenuate the shell mode vibration.

14. The tuned damper of claim 13, wherein the liner is not configured to substantially damp the shell mode vibration occurring at a frequency that is less than or equal to 1000 Hz.

15. The tuned damper of claim 13, wherein the damping member provides broadband damping.

16. The tuned damper of claim 15, wherein the broadband damping includes damping of the shell mode vibration and damping of bending mode vibration at a plurality of frequencies.

17. The tuned damper of claim 15, wherein the damping member is a resistive absorber.

18. The tuned damper of claim 15, wherein the liner is configured to contact an inside surface of the hollow shaft over a first area, wherein the damping member is configured to contact the inside surface of the hollow shaft over a second area, and wherein a ratio of the first area to the second area is less than or equal to five (5) percent.

19. The tuned damper of claim 18, wherein the ratio of the first area to the second area is less than or equal to two and one-half (2.5) percent.

20. The tuned damper of claim 19, wherein the ratio of the first area to the second area is less than or equal to one and one-quarter (1.25) percent.

21. The tuned damper of claim 13, wherein the damping member includes at least one contact member that is configured to contact an inside surface of the hollow shaft and wherein the damping member has a durometer of between 40 Shore A and 80 Shore A.

22. The tuned damper of claim 13, wherein the tubular structure is formed of cardboard.

Description

DRAWINGS

(1) The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

(2) FIG. 1 side, partly sectioned, view of a propshaft assembly constructed in accordance with the teachings of the present disclosure;

(3) FIG. 2 is a schematic illustration of a portion of a driveline illustrating an untreated propshaft vibrating in a second bending mode;

(4) FIG. 3 is a sectional view of a portion of the untreated propshaft taken perpendicular to the longitudinal (rotational) axis of the propshaft illustrating the propshaft vibrating in a first shell mode;

(5) FIG. 4 is a schematic illustration of a portion of a driveline illustrating an untreated propshaft vibrating in a torsion mode;

(6) FIG. 5 is a side view of a portion of the propshaft assembly of FIG. 1 illustrating an intermediate damper in more detail;

(7) FIG. 6 is a right side view of the intermediate damper taken in the direction of arrow 6 in FIG. 5;

(8) FIG. 7 is a cross-sectional view taken along the line 7-7 of FIG. 1; and

(9) FIG. 8 is a schematic illustration in flowchart form of a method for forming a propshaft assembly in accordance with the teachings of the present disclosure.

(10) Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

(11) Example embodiments will now be described more fully with reference to the accompanying drawings.

(12) With reference to FIG. 1 of the drawings, propshaft assembly constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral 10. The propshaft assembly 10 can be employed to transfer rotary power between two driveline components, such as between a transfer case or a transmission and an axle assembly as is disclosed in commonly assigned U.S. Pat. No. 7,774,911, the disclosure of which is incorporated by reference as if fully set forth in detail herein. The propshaft assembly 10 can include a shaft structure 12, first and second trunnion caps 14a and 14b, at least one damper 16, first and second spiders 18a and 18b, a yoke assembly 20 and a yoke flange 22. The first and second trunnion caps 14a and 14b, the first and second spider 18a and 18b, the yoke assembly 20 and the yoke flange 22 can be conventional in their construction and operation and as such, need not be discussed in detail. Briefly, the first and second trunnion caps 14a and 14b can be fixedly coupled to the opposite ends of the shaft structure 12, typically via a weld. Each of the first and second spiders 18a and 18b can be coupled to an associated one of the first and second trunnion caps 14a and 14b and to an associated one of the yoke assembly 20 and the yoke flange 22. The yoke assembly, first spider 18a, and first trunnion cap 14a can collectively form a first universal joint 24, while the yoke flange 22, second spider 18b and second trunnion cap 14b can collectively form a second universal joint 26.

(13) A splined portion of the yoke assembly 20 can be rotatably coupled with the output of a first driveline component, such as an output shaft of a transmission, a power take-off unit, or a transfer case, and the yoke flange 22 can be rotatably coupled with an input shaft of a second driveline component, such as an axle assembly. The first and second universal joints 24 and 26 can facilitate a predetermined degree of vertical and horizontal offset between the first and second driveline components.

(14) The shaft structure 12 can be generally cylindrical, having a hollow central cavity 30 and a longitudinal axis 32. The shaft structure 12 can be formed of any suitable material. In the particular example provided, the shaft structure 12 is formed of welded seamless 6061-T6 aluminum tubing conforming to ASTM B-210. Also in the particular embodiment illustrated, the shaft structure 12 is uniform in diameter and cross-section between the ends 34, but it will be appreciated that the shaft structure could be otherwise formed. For example, the ends 34 of the shaft structure 12 could be necked-down (e.g., via rotary swaging) relative to a central portion 36 of the shaft structure 12.

(15) With reference to FIGS. 2 through 4, it will be appreciated that an undamped propshaft assembly 10 (e.g., the propshaft assembly 10 without the at least one damper 16 of FIG. 1) could be susceptible to several types of vibration. In FIG. 2, for example, the untreated propshaft assembly 10 is illustrated as vibrating at a bending mode natural frequency (i.e., a second bending mode (n=2) natural frequency) of the propshaft assembly 10 as installed in an automotive driveline between the first and second driveline components A and B, respectively. In this regard, those of ordinary skill in the art will appreciate that the bending mode natural frequency is a function of not only the propshaft assembly 10, but also of the boundary conditions (i.e., the manner in which the propshaft assembly 10 is coupled to the remainder of the automotive driveline). Consequently, the term propshaft assembly as installed in the driveline will be understood to include not only the shaft assembly but also the boundary conditions under which the shaft assembly is installed to the first and second driveline components.

(16) In FIG. 3, the propshaft assembly 10 is illustrated as vibrating at a shell mode natural frequency (i.e., a first (n=1) shell mode natural frequency) of the shaft structure 12.

(17) In FIG. 4, the propshaft assembly 10 is illustrated as vibrating at a natural torsion frequency of the driveline 16 in a torsion mode (i.e., a first (n=1) torsion mode). In this regard, those of ordinary skill in the art will appreciate that the natural torsion frequency is a function of not only the propshaft assembly 10, but also of the first and second drive line components A and B to which the propshaft assembly is coupled.

(18) Returning to FIG. 1, the propshaft assembly 10 of the particular example provided includes a damper 16 that comprises two tuned dampers 40 that are identically configured. It will be appreciated in view of this disclosure, however, that other quantities of tuned dampers 40 may be utilized and that the tuned dampers 40 need not be identically configured (i.e., each tuned damper 40 can have different damping characteristics and a first one of the tuned dampers 40 can be different from a second one of the tuned dampers 40). In the particular example provided, each of the tuned dampers 40 comprises an intermediate damper 42 and a damping member 44.

(19) With additional reference to FIGS. 5 and 6, the intermediate damper 42 can be a liner that can have a structure that can be constructed in a manner that is similar to that which is described in U.S. Pat. No. 4,909,361, the disclosure of which is hereby incorporated by reference as if fully set forth in its entirety herein. Briefly, the intermediate damper 42 can include a structural portion 50 and one or more resilient members 52 that are coupled to the structural portion 50. The intermediate dampers 42 are sized such that the structural portion 50 is smaller than the inner diameter of the shaft member 12 (FIG. 1) but the resilient member(s) 52 is/are sized to frictionally engage the inner diametrical surface 54 (FIG. 1) of the shaft member 12 (FIG. 1).

(20) In the example provided, the structural portion 50 includes a hollow core 60, one or more intermediate members 62 and a cover member 64. The core 60 can be formed of a fibrous material, such as cardboard. In the particular example provided, the core 60 is formed of a suitable number of plies of helically wound paperboard. The intermediate members 62 can also be formed of a paperboard and can be helically wound onto and adhered (via a suitable adhesive) to the core 60 in a manner that forms one or more helical gaps 66. In the particular example provided, two helical gaps 66 are formed. It will be appreciated that the structural portion 50 could be formed of any appropriate material, including cardboard, plastic resins, carbon fiber, fiberglass, metal and combinations thereof. It will also be appreciated that the structural portion 50 need not include an intermediate member 62 or a cover member 64 and need not define one or more gaps 66. It will further be appreciated that the gaps 66, if used, need not be helical in shape but rather could be formed in other manners, such as circumferentially or longitudinally.

(21) The resilient members 52 can be formed of an appropriate elastomer and can include a base 70 and one or more lip members 72 that can be coupled to the base 70. The base 70 can be fixedly coupled to the structural portion 50 via a suitable adhesive such that the lip members 72 extend radially outwardly therefrom. The cover member 64 can be wrapped over the intermediate member(s) 62 and the base 70 and can be employed to further secure the resilient members 52 to the structural portion 50.

(22) It will be appreciated from this disclosure that where two or more resilient members 52 are employed, the resilient members 52 can be formed of the same material and are coupled to the structural portion 50 such that their bases 70 are received in an associated gap 66. It will also be appreciated from this disclosure that in the alternative, the resilient members 52 may be formed differently (e.g., with different materials, different sizes and/or different cross-sections).

(23) With reference to FIGS. 1, 5 and 6, it will be further appreciated from this disclosure that the mass and the stiffness of the intermediate damper(s) 42 is/are tuned to the driveline such that the intermediate damper(s) 42 acts or act as one or more of: (i) a tuned reactive absorber for attenuating bending mode vibrations, and (ii) a tuned reactive absorber for attenuating torsion mode vibrations. The intermediate damper(s) 42 is/are not configured to substantially damp shell mode vibration occurring at a frequency that is less than or equal to a predetermined threshold, such as 1000 Hz. The intermediate damper(s) 42 may be tuned such that a ratio of the mass of the intermediate damper(s) 42 to a mass of the shaft member 12 is about 5% to about 30%. In the particular example provided, the ratio of the mass of the intermediate dampers 42 to the mass of the shaft member 12 is about 16.9%.

(24) Where the intermediate damper(s) 42 is/are employed to attenuate bending mode vibrations, they are preferably tuned to a natural frequency corresponding to at least one of a first bending mode, a second bending mode and a third bending mode of the propshaft assembly 10 as installed to the driveline. Where the intermediate damper(s) 42 is/are employed to attenuate torsion mode vibrations, they are preferably tuned to a natural frequency of the driveline in a torsion mode, such as to a frequency that is less than or equal to about 600 Hz.

(25) It will also be appreciated from this disclosure that various characteristics of the intermediate damper 42 can be controlled to tune its damping properties in one or both of the bending mode and the torsion mode. In the particular example provided, the following variables were controlled: mass, length and outer diameter of the intermediate damper 42, diameter and wall thickness of the structural portion 50, material of which the structural portion 50 was fabricated, the quantity of the resilient members 52, the material of which the resilient members 52 was fabricated, the helix angle 80 and pitch 82 with which the resilient members 52 are fixed to the structural portion 50, the configuration of the lip member(s) 72 of the resilient member 52, and the location of the dampers 16 within the shaft member 12. In the particular example provided: the shaft member 12 can have an outside diameter of between about 3.0 inches to about 5.8 inches, a wall thickness of about 0.08 inch, a length of about 64 inches, and can have a mass of about 3.2 kg; the intermediate dampers 42 can have an outer diameter (over the resilient member(s) 52) of about 4.0 inches, a length of about 14 inches, a mass of about 270 grams, the structural portion 50 of the intermediate dampers 42 can be formed of paperboard and can have a wall thickness of about 0.07 inch and an inner diameter of about 3.56 inch, a pair of resilient members 52 can be coupled to the structural portion 50 offset 180 degrees from one another and each can have a helix angle 80 of about 22.5? and a pitch 82 of about 4.5 inches, each resilient member 52 can have a single lip member 72 and can be formed of a silicon material that conforms to ASTM D2000 M2GE505 having a durometer of about 45 Shore A to about 55 Shore A; and each of the intermediate dampers 42 can be configured to be inserted into an associated end of the shaft member 12 such that they are disposed generally symmetrically about an associated one of the second (n=2) bending anti-nodes N (FIG. 1).

(26) It will be appreciated that in certain situations it may not be possible to exactly tune the intermediate damper 42 to the relevant frequency or frequencies associated with a given propshaft assembly 10, as when a particular damper 16 is used across a family of propshaft assemblies. As such, it will be understood that an intermediate damper 42 will be considered to be tuned to a relevant frequency if it is effective in attenuating vibration at the relevant frequency. For example, the intermediate damper 42 can be considered to be tuned to a relevant frequency if a frequency at which it achieves maximum attenuation is within ?20% of that relevant frequency. Preferably, the intermediate damper 42 is considered to be tuned to the relevant frequency if the frequency at which it achieves maximum attenuation is within ?15% of the relevant frequency. More preferably, the intermediate damper 42 is considered to be tuned to the relevant frequency if the frequency at which it achieves maximum attenuation is within ?10% of the relevant frequency. Still more preferably, the intermediate damper 42 is considered to be tuned to the relevant frequency if the frequency at which it achieves maximum attenuation is within ?5% of the relevant frequency.

(27) With reference to FIGS. 1 and 7, the damping member 44 can be coupled to the intermediate damper 42 and can be configured to primarily attenuate shell mode vibration at one or more desired frequencies, but also to provide damping of at least one of bending mode vibration and torsion mode vibration. In the example provided, the damping member 44 provides broadband damping (i.e., damping at a plurality of frequencies) of shell mode vibration and broadband damping of at least one of bending mode vibration and torsion mode vibration. If desired, the damping member 44 can be tuned to a natural frequency corresponding to at least one of a first shell mode, a second shell mode and a third shell mode. It will be understood that a damping member 44 (as coupled to the intermediate damper 42) will be considered to be tuned to a relevant frequency if it is effective in attenuating shell mode vibration at the relevant frequency. For example, the damping member 44 (as coupled to the intermediate damper 42) can be considered to be tuned to a relevant frequency if a frequency at which it achieves maximum attenuation is within ?20% of that relevant frequency. Preferably, the damping member 44 (as coupled to the intermediate damper 42) is considered to be tuned to the relevant frequency if the frequency at which it achieves maximum attenuation is within ?15% of the relevant frequency. More preferably, the damping member 44 (as coupled to the intermediate damper 42) is considered to be tuned to the relevant frequency if the frequency at which it achieves maximum attenuation is within ?10% of the relevant frequency. Still more preferably, the damping member 44 (as coupled to the intermediate damper 42) is considered to be tuned to the relevant frequency if the frequency at which it achieves maximum attenuation is within ?5% of the relevant frequency. As another example, the damping member 44 (as coupled to the intermediate damper 42) can be considered to be tuned to a relevant shell mode frequency if damps shell mode vibrations by an amount that is greater than or equal to about 2%.

(28) The damping member 44 can be a resistive absorber and can be configured to contact an inside surface 54 of the shaft member 12 over a relatively large surface area as compared with the area over which the intermediate damper 42 contacts the inside surface of the shaft member 12. For example, a ratio of the area over which the intermediate damper 42 contacts the inside surface of the shaft member 12 to the area over which the damping member 44 contacts the inside surface of the shaft member 12 can be less than or equal to five percent (5%), preferably less than or equal to two and one-half percent (2.5%) and more preferably less than or equal to one and one-quarter percent (1.25%). The damping member 44 can comprise a contact member 90 that is configured to contact the inside surface of the shaft member 12 and can be formed of a material having a durometer of about 40 Shore A to about 80 Shore A. The contact member 90 may be coupled to the intermediate damper 42 in any desired manner. For example, the contact member 90 can be configured as a strip of material that can be wound onto (and bonded to) the structural portion 50 in the space between the helix of the resilient members 52.

(29) With reference to FIG. 8, a method for forming a shaft assembly for a driveline system is schematically illustrated in flowchart form. It will be appreciated that the driveline system includes first and second driveline components and that the shaft assembly is configured to transmit torque between the first and second driveline components. The method can start at bubble 100 and proceed to block 102 where a hollow shaft is provided. The methodology can proceed to block 104.

(30) At block 104 a set of intermediate dampers 42 (FIG. 1) can be formed by tuning the mass and stiffness of a set of liners to attenuate at least one of bending moment vibration and torsion mode vibration that occurs at a first predetermined frequency. The method can progress to block 106.

(31) In block 106 the set of intermediate dampers 42 (FIG. 1) can be tuned to form a set of tuned dampers that can attenuate the bending and/or torsion mode vibration at the first predetermined frequency as well as shell mode vibration. A damping member 44 (FIG. 1) can be coupled to each of the intermediate dampers 42 (FIG. 1) as part of the tuning process. The damping member 44 (FIG. 1) can achieve broadband damping, such as broadband damping of shell mode vibration and optionally bending mode vibration. The methodology can proceed to block 108.

(32) In block 108 the set of tuned dampers can be inserted into the hollow shaft member. The method can continue to bubble 110 where the methodology ends.

(33) The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.