JP2001145850A - Driving shaft pipe used in driving line assembly of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezo-based device which effectively reduces the quantity of vibration generated in the driving shaft pipe of a driving line assembly during operation. SOLUTION: The piezo-based device 30 is used for damping the vibration of the driving shaft pipe 18 by converting the vibration into an electric current which disperses the vibration as heat via a resistance element 31. By changing the size of the resistance element, the central damped oscillation frequency of the device 30 can be changed as required for a specified driving shaft pipe and a specified driving line assembly. The stiffness of the device 30 is controlled by a power source which can be actuated by a controller corresponding to the size and frequency of oscillation detected by a sensor. The device 30 can be fitted to the outer surface or inner surface of the driving shaft pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a structure for actively and passively damping the vibration of a drive train assembly of a vehicle. More particularly, the present invention is directed to a piezo mounted on or otherwise secured to a driveshaft tube of a vehicle drive train assembly for actively and passively reducing torsional and lateral vibrations generated during use.・ Base device (p
iezo-based device).

[0002]

2. Description of the Related Art Torque transmission shafts are widely used to transmit rotary power between a rotary power source and a rotary driven mechanism. One well-known example of a torque transmitting shaft is a drive shaft tube used in a drive train assembly of a vehicle. The drive train assembly
Rotational power is transmitted from a source such as an engine and transmission assembly to a driven component such as an axle assembly having a pair of driven wheels. A typical vehicle drive train assembly includes a hollow cylindrical drive shaft tube having end fittings secured to each end. Typically, each end fitting is formed as an end yoke adapted to cooperate with each universal joint. Such drive train assemblies are often used to form a rotary drive connection between an output shaft of a vehicle engine and transmission assembly and an input shaft of an axle assembly for rotationally driving wheels of the vehicle.

[0003] One problem with vehicle drive train assemblies and other rotating structures is that they vibrate during operation, producing and transmitting undesirable audible noise. It is known that all mechanical objects have a natural resonance frequency that oscillates when operating at a certain rotational speed. This natural resonance frequency is a natural property of the mechanical object and is based on many factors, including the composition, dimensions and shape of the object. In the context of a vehicle drive train assembly, the engine and transmission assembly can optionally produce enhanced vibration transmitted and enhanced during rotation by the driveshaft tube. Also, the driveshaft tube itself rotates at or near the natural resonance frequency (or one or more of its harmonics) that induces vibration. In each case, the vibrations that occur in the driveshaft tube cause audible noise. Such noise is usually considered undesirable for obvious reasons.

[0004] Proposals have been made to reduce the noise generated by the drive shaft tube of a vehicle during driving. For example, it has been found desirable to arrange one or more noise reduction structures within a hollow driveshaft tube to absorb some of the noise generated during use. Known noise reduction structures are made of many materials, including cardboard, foam, and the like. However, while known noise reduction structures are relatively simple and inexpensive in construction and installation, it has been found that these structures are relatively ineffective at reducing noise in some drive shaft tubes of vehicles.
That is, it is desirable to provide a novel structure for a vehicle drive train assembly that reduces the amount of vibration and noise generated during operation.

[0005]

SUMMARY OF THE INVENTION The present invention provides a novel structure that reduces the amount of vibration and noise generated during operation of a drive train assembly of a vehicle.

A piezo-based device is attached or otherwise attached to a drive shaft tube or other component of a drive train assembly. Piezo-based devices are used to attenuate these vibrations by converting the physical oscillatory motion of the driveshaft tube into a current that is dissipated as heat through a resistive element. By varying the size of the resistive element, the center damping frequency of the piezo-based device can be varied as needed for a particular driveshaft tube and drivetrain assembly as a whole. If desired, an inductive element may be provided in a circuit having a resistive element to dissipate the current. The magnitude of the resistive element may be varied by the controller in response to the magnitude and / or frequency of the vibration sensed by the sensor. Alternatively, the stiffness of a piezo-based device can be controlled by a current source (e.g., el.
electrical current generator
r). The piezo-based device is mounted on the outer or inner surface of the driveshaft tube. Or piezo
The base device may be provided in the driveshaft tube or may be formed integrally with the tube. If desired, a plurality of such piezo-based devices may be provided on the driveshaft tube.

[0007] The various objects and advantages of the present invention will be described in detail below with reference to the accompanying drawings with reference to the preferred embodiments of the present invention.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, FIG. 1 illustrates a drive train assembly 10 for a vehicle according to a first embodiment of the present invention. Drive train assembly 10 includes a transmission 12 having an output shaft (not shown) coupled to an input shaft (not shown) of axle assembly 14 via a drive shaft assembly 16. The transmission 12 is rotationally driven by an engine (not shown) that generates rotational power in a conventional manner. Drive shaft assembly 16
Comprises a cylindrical drive shaft tube 18 having a central portion and a pair of opposing end portions. The output shaft of transmission 12 and the input shaft of axle assembly 14 are typically not coaxially aligned with one another. For this purpose, a pair of universal joints 24a, 2
4b are provided at each end of the drive shaft tube 18 so as to connect these end portions of the drive shaft tube 18 to the output shaft of the transmission 12 and the input shaft of the axle assembly 14, respectively.
The first universal joint 24a includes a tube yoke 26a fixed to the front end of the drive shaft tube 18 by any conventional means, for example, by welding. The first universal joint 24a further includes a cross member 27a connected to the tube yoke 26a in a conventional manner.
Is provided. Finally, the first universal joint 24a is connected to the transmission 12
End yoke 2 connected to the output shaft and to the cross member 27a
8a. Similarly, the second universal joint 24b comprises a tube yoke 26b secured to the rear end of the drive shaft tube 18 by any conventional means, for example, by welding. The second universal joint 24b further comprises a cross member 27b connected to the tube yoke 26b in a conventional manner. Finally, the second universal joint 24b includes an end yoke 28b connected to the cross member 27b and to the input shaft of the axle assembly 14. The drive train assembly 10 described above is of any conventional construction that is conventional in the art and transmits rotational power from a source to a driven device.

As is well known, the operation of the engine usually causes various vibrations in the drive shaft tube 18. Also, in some instances, the drive shaft tube 18 may rotate at or near the natural resonance frequency of the drive shaft tube 18 that induces vibration. Such vibrations, regardless of their source, cause undesirable audible noise. For this, piezo-based
Device (piezo-based device) 3
0 is assembled or otherwise attached to the driveshaft tube 18. The structure and operation mode of the piezo-based device 30 will be described later in detail. In general, however, the piezo-based device 30 can be used to damp these vibrations by converting the physical oscillatory motion of the driveshaft tube 18 into a current that is dissipated as heat through the resistive element. By varying the size of the resistive element, the center damping frequency of the piezo-based device 30 can be varied as needed for a particular driveshaft tube 18 and drive train assembly 10. Alternatively, or as described in more detail below, the piezo-based device 30 can be used as an active actuator. This actuator uses a piezo
Passing a current through a base device causes a change in its stiffness or flexibility. The present invention provides for one or more piezo-based devices 30 to be mounted on the inner or outer surface of the drive shaft tube 18 or provided within or integrally formed with the drive shaft tube 18 as a whole. The torsional and lateral vibrations of the drive shaft tube 18 and the drive train assembly 10 of the vehicle are passively or actively controlled.

As will be described in detail later, piezo-based
The device 30 is composed of a piezoelectric material (piezo-electric).
c material). In general, a piezoelectric material is any material that generates an electrical output when subjected to the effects of mechanical stress or deformation or vice versa. Typically, when the piezoelectric material receives mechanical strain due to vibration or the like generated in the drive shaft tube 18 during operation,
It becomes electrically polarized. The present invention allows any known piezoelectric material to be used in the piezo based device 30, including piezo ceramic materials such as lead zirconium titanate.

FIG. 2 shows a first embodiment of a piezo-based device 30. As shown in FIG. 2, the piezo-based device 30 includes an element 31 formed of a piezoelectric material,
And a resistor 32 connected in series electrical circuit. In addition to producing an electrical output when subjected to mechanical stress, the element 31 acts electrically as a capacitor. That is, the piezo-based device 30 is substantially an RC electrical circuit. When the engine is operated to rotate the drive shaft tube 18, vibration occurs in the drive shaft tube 18. These vibrations induce mechanical stress on element 31 and cause the element to generate an electrical output (eg, voltage). This voltage is converted to a current through resistor 32. In this case, this current is dissipated as heat. Therefore, the piezo-based device 30 functions to passively attenuate the vibration generated in the drive shaft tube 18.

As is well known, an RC electric circuit comprises:
It has a center damping frequency determined by the magnitude of the resistance and capacitance of this circuit. The center damping frequency is desirably selected so as to be close to the frequency of the vibration of the drive shaft tube 18, which is desirably damped by the piezo-based device 30. The desired resistance magnitude for resistor 32 can be calculated using the following relationship: R
= {[1- (λk ² ) / (1-k ² )] ^1/2 } / CW
In this equation, R is equal to the resistance of the resistor 32, and C is the material 31
, K is equal to the lateral coupling constant,
λ is equal to the strain energy capture and W is equal to the frequency of the oscillation to be damped. The piezo-based device 30 is connected to the drive shaft tube 1 of the drive train assembly 10 of the vehicle.
8 or any other part at any desired location. For example, the piezo-based device 30 is preferably provided at each portion of the universal joints 24a, 24b or elsewhere in the drive train assembly 10 of the vehicle. Piezo-based device 30 of drive shaft tube 18
The most effective location can be determined based on structural modeling, modal analysis and actual experiments. However, in general, the piezo-based device 30 will normally drive the axle 18 in the area of maximum strain to reduce the maximum amount of vibration.
Position. The piezo-based device 30 may be attached to the drive shaft tube 18 by an adhesive or fixed by any other known method.

[0013] The physical dimensions of the piezo-based device 30 can also be varied as desired. By associating more piezoelectric material with the piezo-based device 30, more strain energy can be captured and converted to heat. However, the addition of such a substance increases the weight and affects the rotational balance of the drive shaft tube 18. The amount of piezoelectric material provided in the element 31 varies with each addition according to the number of factors. Piezo based device 30
The relationship between the damping τ of and the strain energy capture λ is given by τ = １ ／ [(λk ² ) / (1−k ² )] ^1/2 where λ is equal to the strain energy capture and k is equal to the lateral coupling constant.

FIG. 3 shows a piezo-based device 40 according to a second embodiment. As shown in FIG. 3, the piezo-based device 40 includes an element 41 formed of a piezoelectric material, a resistor 42, and an inductor 42, which are connected in a series electric circuit. That is, the piezo-based device 40 is substantially an RLC electrical circuit. Piezo
The base device 40 is the piezo base device described above.
Drive shaft tube 18 functions in substantially the same manner as device 30.
Is passively damped. The addition of inductor 43 allows more current to pass through resistor 42, producing a damping action that is more sophisticated than piezo-based device 30 described above, but over a narrower damping frequency range. The magnitude of the desired resistance for resistor 42 and the magnitude of the inductance of inductor 43 can be calculated using the following relationship: L = ｛CW ² [1+ (λk ² ) / (1-
k ² )] ^{1/2 −１ −1} and R = ｛(2) ^1/2 [(λk ² ) / (1-k ² )]
^1/2} / {CW ^{[1+ (λk 2) / (1} -k 2) ]} R is equal to the resistance expression of this like, C is equal to the capacitance, k is equal to the transverse coupling constant, lambda is the strain Equivalent to energy capture, w is equal to the frequency of the oscillation to be damped. The piezo-based device 40 is suitable for use in a touring vehicle, for example when the target mode of vibration is a higher bending mode. The frequency of this bending mode does not change much with actual boundary conditions because the road surface is relatively uniform. That is, the piezo-based device 4
0 is a single center damping frequency, which increases the variable damping action.

FIG. 4 shows a piezo-based device 50 according to a third embodiment of the present invention. As shown in FIG. 4, the piezo-based device 50 includes an element 51 formed of a piezoelectric material and a resistor 52, which are connected in a series electric circuit. That is, the piezo-based device 50 is substantially an RC electrical circuit. The magnitude of the resistance of the resistor 52 is variable and is controlled by the controller 53 in response to the magnitude and / or frequency of the vibration sensed by the sensor 54. The controller 53 may be a microprocessor or similar device capable of changing the resistance of the resistor 52 in response to the sensed vibration and may be included in the driveshaft tube 18 of the vehicle or mounted elsewhere. The sensor 54 is
It may be formed as one or more known sensing devices directly on the driveshaft tube 18 or on any other desired portion of the drive train assembly 10 of the vehicle and the magnitude and / or magnitude of the vibrations that occur on the driveshaft tube 18 An electric signal representing the frequency can be sent to the control device 53. The piezo-based device 50 functions in substantially the same manner as the piezo-based device 30 described above,
8 is passively damped, but can be tuned during operation of the vehicle's drive train assembly 10 according to general conditions. The variable resistor 52, the control device 53, and the sensor 54 may cooperate with the RLC circuit illustrated in FIG.

FIG. 5 shows a piezo-based device 60 according to a fourth embodiment. As shown, the piezo-based device 60 comprises an element 61 made of piezoelectric material and a current source 62, which are connected in a series electrical circuit. The current source 62 is conventional in the art and the sensor 64
Is controlled by the controller 63 in response to the magnitude and / or frequency of the vibration detected by the control unit 63. Controller 63 may be a microprocessor or similar device capable of changing the amount of current supplied to element 61 in response to sensed vibration and may be included within drive shaft tube 18 or mounted elsewhere in the vehicle. I just need. The stiffness of the element 61 is controlled according to the magnitude of the current supplied thereto by the current source 63. Sensor 64
May be formed as one or more known sensing devices and may be mounted directly to the driveshaft tube 18 or to any other desired portion of the drive train assembly 10 of the vehicle, and the magnitude of the vibration generated in the driveshaft tube 18 And / or send an electrical signal indicating the frequency to the control device 63. The piezo-based device 60 functions to actively dampen vibrations that occur in the driveshaft tube 18.

FIG. 6 shows a vehicle drive train assembly 10 'according to a second embodiment with a piezo-based device 30' assembled or otherwise attached to the inner surface of the drive shaft tube 18. The structure and mode of operation of the piezo-based device 30 'is the same as described above for any of FIGS. 2, 3, 4, or 5, or any combination thereof. Alternatively, the piezo-based device 30 ′ can be provided within the drive shaft tube 18 or formed integrally therewith. Such a structure is suitable even if the drive shaft tube 18 is formed of a composite material, for example.

FIG. 7 shows a vehicle drive train assembly 10 according to a third embodiment having a pair of piezo-based devices 30a, 30b assembled or otherwise attached to the outer surface of drive shaft tube 18. The structure and mode of operation of the piezo-based devices 30a, 30b may be the same as described above for any of FIGS. 2, 3, 4, or 5, or any combination thereof. Alternatively, one or both of the piezo-based devices 30a, 30b may be provided within the drive shaft tube 18 or formed integrally with the drive shaft tube 18 as shown in Fig. 5. If desired, the drive shaft tube 18
May be provided with a greater number of such piezo-based devices 30a, 30b. Due to the various forces applied to the driveshaft tube 18 during operation, the use of a plurality of piezo-based devices 30a, 30b allows the driveshaft tube 1
A number of regions can produce damping effects.
Further, since each piezo-based device 30a, 30b produces a damping action over a single frequency range determined by the center damping frequency, the plurality of piezo-based devices 30a, 30b are tuned to different center damping frequencies. This causes damping effects over many types of frequency ranges. Also, a passive piezo-based device is used to generate the power to operate the active piezo-based device.

The principles and modes of operation of this invention have been described with reference to a preferred embodiment. However, it goes without saying that the present invention can be subjected to various changes and modifications without departing from the spirit thereof.

[Brief description of the drawings]

FIG. 1 is a side view of a drive train assembly of a vehicle according to a first embodiment including a drive shaft tube having a piezo-based device according to the present invention mounted on an outer surface thereof.

FIG. 2 is a wiring diagram of a first embodiment of the piezo-based device illustrated in FIG. 1;

FIG. 3 is a wiring diagram of a second embodiment of the piezo-based device illustrated in FIG. 1;

FIG. 4 is a wiring diagram of a third embodiment of the piezo-based device illustrated in FIG. 1;

FIG. 5 is a wiring diagram of a fourth embodiment of the piezo-based device illustrated in FIG. 1;

FIG. 6 is a side view of a drive train assembly of a vehicle according to a second embodiment with a piezo-based device according to the present invention mounted on or integrally formed with an inner surface.

FIG. 7 is a side view of a drive train assembly of a vehicle according to a third embodiment having a drive shaft tube to which a plurality of piezo-based devices are mounted according to the present invention.

[Explanation of symbols]

 Reference Signs List 10 Drive train assembly of vehicle 18 Drive shaft tube 30 Piezo-based device

Claims (10)

[Claims] A drive shaft tube; a piezo-based device fixed to the drive shaft tube so as to attenuate vibrations generated in the drive shaft tube;
A driveshaft tube for use in a drive train assembly of a vehicle, comprising: 2. The drive shaft tube according to claim 1, wherein said piezo-based device is formed of a piezoelectric material. 3. The driveshaft tube of claim 1, wherein said piezo-based device is connected to a resistive element in an electrical circuit. 4. The driveshaft tube of claim 1, wherein said piezo-based device is connected to a resistive element and an inductive element in an electrical circuit. 5. The driveshaft tube according to claim 1, wherein said piezo-based device is connected to a variable resistance element in an electric circuit. 6. The drive shaft tube according to claim 5, further comprising a control device for changing a resistance of said variable resistance element. 7. The apparatus according to claim 1, further comprising a sensor for generating a signal indicating vibration of the drive shaft tube, wherein the control device changes a resistance of the resistance element in response to the signal from the sensor. 6 drive shaft tube. 8. The driveshaft tube of claim 1, wherein said piezo-based device is connected to a current source in an electrical circuit. 9. The driveshaft tube according to claim 8, further comprising a control device for controlling the operation of the current source. 10. The apparatus according to claim 1, further comprising a sensor for generating a signal indicating vibration of said drive shaft tube, wherein said control device controls operation of said current source in response to said signal from said sensor. Item 9. A drive shaft tube according to item 9.