JPH054597Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a dynamic damper for damping forced vibrations caused by rotational fluctuations as seen in, for example, vehicle drive systems.

(Prior Art) The basic structure of this type of dynamic damper is a mass member with a constant mass, and a spring between this mass member and a predetermined vibration damping object (hereinafter referred to as the main vibration body). It consists of a combination with an elastic material such as rubber that exhibits its properties.

As a dynamic damper used in a vehicle drive system, one is known in which an elastic body such as rubber is fixed to the outer periphery of a rotating shaft, etc. in the drive system, and a mass member is further fixed to the outer periphery of this elastic body. (For example, see Japanese Utility Model Application Publication No. 58-76843).
The structure of a dynamic damper that is almost similar to this is disclosed in Japanese Utility Model Application No. 59-3041 or Japanese Patent Application Laid-open No. 58-58.
It is also disclosed in Publication No. 177720 and the like.

(Problems to be Solved by the Invention) As is well known, the natural frequency of a dynamic damper is determined by the mass of its mass member and the spring constant of the elastic body. Therefore, the natural frequency of a typical dynamic damper is set so that the vibration damping effect is most effective in a specific forced vibration frequency range of the main vibrating body. In other words, the damping effect of a dynamic damper is at its maximum when its natural frequency is optimal (almost the same) as the frequency of the main vibrating body, but if this balance is disrupted, the damping effect decreases. This results in a large decrease.

This is especially true when the main vibrating body is the vehicle drive system, and in vehicles where the mounting space for the dynamic damper and the mass of the mass members are limited.
The actual situation is that vibration damping effects cannot be expected in areas other than a specific forced vibration frequency range.

The present invention aims to solve these problems.

(Means for Solving the Problems) In order to solve the above problems, the dynamic damper of the present invention is constructed as follows.

That is, a sun gear of a planetary gear set fixed to the main vibrating body where forced vibration occurs, a ring gear arranged via a plurality of pinions positioned with respect to the sun gear by a carrier,
A mass member fixed to the ring gear, an elastic body that exhibits spring characteristics in the torsional direction due to relative rotation between the main vibrating body and the mass member, and the main vibrating body and the mass member. an electromagnet that exerts an electromagnetic attractive force in parallel with the spring characteristics of the elastic body, and control that controls the current value flowing through the electromagnet to increase or decrease in proportion to the change in the forced frequency of the main vibrating body. Equipped with equipment.

(Function) According to the configuration, when the sun gear rotates due to rotational fluctuations of the main vibrating body, the ring gear rotates together with the mass member while torsionally deforming the elastic body through rotation of the pinion of the planetary gear set. At this time, the rotational fluctuation of the main vibrating body is damped by the damping rate of the dynamic damper based on the spring characteristics of the elastic body and the mass of the mass member.

The rotation of the sun gear is transmitted to the ring gear and the mass member at increased speed by the gear ratio of the planetary gear set. Therefore, the moment of inertia of the dynamic damper is amplified, and the damping effect against rotational fluctuations of the main vibrator is enhanced.

At the same time, as the mass member 17 rotates, the electromagnetic attraction force of the electromagnet 20 is applied to the elastic body 18 between the mass member 17 and the main vibrating body.
This acts in parallel with the spring characteristic of the dynamic damper, and assists the above-mentioned spring constant of the dynamic damper. The electromagnetic attraction force generated by the electromagnet 20 is controlled by the function of the control device 40 so as to increase or decrease in proportion to a change in the forced frequency of the main vibrator. Therefore, the natural frequency of the dynamic damper becomes variable in accordance with the forced vibration frequency of the main vibrator, and the forced vibration of the main vibrator is damped in a wide frequency range.

(Example) Next, the configuration of the present invention will be explained by referring to an example of a dynamic damper for a vehicle drive system shown in the drawings.

First Embodiment First, in FIG. 1 and FIG. 2, which is a cross-sectional view taken along the line - in FIG. There is. This support plate 3
One end of a support shaft 5 disposed on the rotational axis of the propeller shaft 1 is attached to the propeller shaft 1 by fixing means such as press fitting. In other words, the support shaft 5 constitutes a component of the vehicle drive system, which is a main vibrating body, and rotates together with the propeller shaft 1 through the support plate 3.

A sun gear 11 of a planetary gear set 10 is assembled on the outer periphery of the support shaft 5 in a centered manner from the left direction in FIG. A nut 7 is fastened to the end of the support shaft 5 via a retainer 6, thereby fixing the sun gear 11 so as to rotate together with the support shaft 5. Furthermore, a planetary gear set 10 is arranged on the outer periphery of the sun gear 11 inside the propeller shaft 1.
A cylindrical mass member 17 is fixed to the ring gear 16 by means such as press fitting so as to rotate together with the ring gear 16. The right end of the mass member 17 is held centered with respect to the support shaft 5 by a bush 8.

A plurality of pinions 13 (four in the drawing) are installed between the sun gear 11 and the ring gear 16. These pinions 13 are rotatably supported by respective shafts 14 fixed to a cylindrical carrier 15.

On the outer periphery of the sleeve 12, which is fixed to the outer periphery of the extension part 11a of the sun gear 11 by means such as press fitting, the inner periphery of an elastic body 18 formed in an annular shape from a material such as rubber is attached by means such as vulcanization adhesion. It is fixed. Further, the outer periphery of the elastic body 18 is fixed to the inner periphery of the carrier 15 by means such as vulcanization adhesion.

The above elastic body 18 includes the sun gear 11 and the carrier 1.
5, and this elastic body 18 may be provided between the sun gear 11 and the ring gear 16 (mass member 17). Further, it is only for manufacturing convenience that the elastic body 18 is fixed to the outer periphery of the sun gear 11 by the sleeve 12.
Of course, it is also possible to fix directly to the outer periphery of the extension portion 11a of the sun gear 11 or the outer periphery of the support shaft 5.

A sleeve 26 equipped with an electromagnet 20 is fixed to the outer periphery of the support shaft 5 between the elastic body 18 and the bush 8 by means such as press fitting.
This electromagnet 20 has a plurality of (four in the drawing) iron core portions 20a, as is clear from FIG. 3, which shows a cross section taken along the line - in FIG. has been done. On the inner circumferential surface of the mass member 17, protrusions 17a that protrude toward the iron cores 20a of the electromagnet 20 are formed at locations corresponding to the iron cores 20a of the electromagnet 20, respectively.

When each coil 21 is energized, the electromagnetic attraction force of the electromagnet 20 acts on each protrusion 17a of the mass member 17, and the positional relationship between the support shaft 5 and the mass member 17 in the rotational direction is changed as shown in the figure. A force acts to hold it in that state. This has the same effect as the spring characteristic of the elastic body 18 in the torsional direction, that is, it acts in parallel with this to assist the spring characteristic of the elastic body 18.

In FIG. 1, a pair of slip rings 2 are attached to the outer periphery of the propeller shaft 1 near a center bearing 2 that rotatably supports an intermediate joint portion (not shown) of the propeller shaft 1.
2 is fixed. Also, center bearing 2
A member 2a fixed to the body side of the vehicle at
A brush 23 is provided in electrical contact with each slip ring 22 described above. Each of these slip rings 22 is electrically connected to each coil 21 of the electromagnet 20, and one of them is connected to the body ground 25 through its brush 23, and the other is connected to the vehicle through its brush 23. It is connected to the power supply circuit 24 of. This power supply circuit 24 is adapted to flow a current to the electromagnet 20 in accordance with the electric signal from the control device 40 shown in FIG. 1.

Now, the above-mentioned control device 40 calculates the current value to be passed through the coil 21 of the electromagnet 20 based on the electric signal (pulse signal) from the engine rotation sensor 27 that detects the rotation speed of the vehicle engine,
A microcomputer 41 outputs this as an electric signal, and a digital computer converts this electric signal into an analog signal and sends it to the power supply circuit 24.
An analog converter 42 is provided. The microcomputer 41 also includes a read-only memory (ROM) 41a that stores a program corresponding to the flowchart shown in FIG. 4, and a central processing unit (CPU) 41b that executes this program.
A writable memory (RAM) 41c that temporarily stores variables necessary for this program, and an input that inputs the pulse signal from the engine rotation sensor 27 and outputs a predetermined electrical signal to the digital-to-analog converter 42. Output interface 4
1d, and a bus 41e that commonly connects the read-only memory 41a, central processing unit 41b, writable memory 41c, and input/output interface 41d.

Next, the flowchart shown in FIG. 4 will be explained. First, when the ignition switch (not shown) is turned on to drive the engine, the central processing unit 4 of the microcomputer 41 mentioned above
1b starts execution of the program. Therefore, in step 100 of FIG. 4, the engine rotation speed N detected by the engine rotation sensor 27 is input and stored in the writable memory 41c. Then step
At step 101, it is determined whether the engine rotational speed N is (1500rpm<N<3500rpm). If the engine speed N is within this range, YES is determined in step 101, and the voltage E is applied to the power supply circuit 24 in the next step 102.
Outputs a signal for applying. Note that this voltage E is determined by (E=f·N), and a voltage corresponding to the engine rotation speed N is obtained.

Further, if the engine speed N is in a range other than (1500 rpm<N<3500 rpm) in step 101, a negative determination is made, and in step 103, a signal for applying voltage E0 to the power supply circuit 24 is output. However, the voltage E0 at this time is set to O volts.

After outputting the respective signals in step 102 and step 103, the process returns to step 100, and the circulation process continues.

It should be noted that the range of the engine speed N determined in step 101 above is 1500 rpm to 3500 rpm in one embodiment, and the range of the engine speed N varies depending on the type of vehicle.

Next, the determination of its specifications will be explained with reference to FIG. 5, which is a schematic diagram of the dynamics of a general dynamic damper. First, in FIG. 5, M indicates the mass of the main vibrating body, and in the case of a vehicle drive system, it is the total mass of the transmission, propeller shaft, differential device, etc. m is the mass of the dynamic damper, and in this embodiment is the mass of the mass member 17 including the ring gear 16. Further, K is the spring constant of the main vibrating body, and in the case of a vehicle drive system, is its rigidity. k is the spring constant of the dynamic damper, and c is the damping coefficient of the dynamic damper. Further, F is an excitation force, and in the case of a vehicle drive system, it is generated due to rotational fluctuations due to engine explosion, etc. Furthermore, X1,
X2 is the displacement of the main vibrator and the dynamic damper.

Now, when the above M is displaced by the excitation force Fsinωt, if m is added to this M to suppress the displacement of M, the parameter that minimizes the vibration of M can be given by the following formula. Generally known.

Xst=F/K: Static deflection of the main vibrator Ωn=√: Natural frequency of the main vibrator ωn=√: Natural frequency of the dynamic damper μ=m/M: Mass of the dynamic damper and the main vibrator Ratio ζ=c/2√: Damping rate of dynamic damper ωn/Ωn=1/(1+μ) (optimal tuning) ……(1) ζ=√38(1+) ³ (optimal damping) ……(2) This The natural frequency ωn of a dynamic damper is determined by its spring constant k and mass m, and when the main vibrating body is a vehicle drive system, the natural frequency ωn of the dynamic damper is determined by the engine speed. It is tuned to the lower limit of the primary explosion frequency. Note that the forced vibration frequency in the vehicle drive system is caused by rotational fluctuations caused by engine explosion, so the frequency is the engine explosion primary (rotational secondary for a 4-cylinder engine, rotational tertiary for a 6-cylinder engine) frequency.

Furthermore, the optimum damping by the dynamic damper is determined by the above equation (2). However, the damping rate ζ of the dynamic damper determined by this equation (2) is obtained when the spring constant k of the dynamic damper is fixed. On the other hand, if the spring constant k of the dynamic damper is made variable and its natural frequency ωn is matched to the forced frequency of the vehicle drive system, which is the main vibrating body, the frequency response of the well-known dynamic damper is As is clear from FIG. 6, which shows the curve, the damping effect on the main vibrator is enhanced.

In the dynamic damper configured as described above, when the sun gear 11 of the planetary gear set 10 causes rotational fluctuation due to rotational fluctuation of the vehicle drive system, which is the main vibrating body, this planetary gear set 1
With a gear ratio of 0, the ring gear 16 including the mass member 17 rotates while deforming (twistingly deforming) the elastic body 18. In this case, the above ring gear 16
The natural frequency of the dynamic damper, which is determined by the mass of the mass member 17 including By setting this value, a sufficient vibration damping effect can be achieved against forced vibrations of the vehicle drive system in this range.

As the engine speed increases, its primary explosion frequency also increases, which causes the above-mentioned natural frequency of the dynamic damper to gradually deviate from the forced frequency of the vehicle drive system, reducing its damping effect. shows a tendency to

Under such circumstances, in this embodiment, when the engine speed falls within the range of, for example, 1500 rpm to 3500 rpm, the microcomputer 41 of the control device 40 transmits the current information to the power supply circuit 24 through the digital-to-analog converter 42. A signal is sent to apply a voltage according to the engine speed. As a result, a current flows through each coil 21 of the electromagnet 20 in accordance with the engine speed, and an electromagnetic attractive force is generated between the support shaft 5 and each protrusion 17a of the mass member 17. The electromagnetic attraction force by the electromagnet 20 functions in parallel with the spring characteristics of the elastic body 18 between the main vibrating body and the mass member 17 of the dynamic damper, so the electromagnetic attraction force by the electromagnet 20 functions in parallel with the spring characteristic of the elastic body 18 between the main vibrating body and the mass member 17 of the dynamic damper. This will assist the spring constant k of the damper. In other words, the spring constant k of the dynamic damper depends on the engine speed.
is proportionally increased or decreased to match the natural frequency ωn of the dynamic damper to the forced frequency of the main vibrator. Thereby, the forced vibration of the main vibrator can be attenuated in a wide frequency range.

In addition, the above-mentioned control device 40 controls the electromagnet 20 at engine rotation speeds other than those that require the electromagnetic attraction force of the electromagnet 20 (1500 rpm to 3500 rpm in this embodiment).
Since a signal is generated that does not cause current to flow through the coil 21, wasteful consumption of a battery (not shown) in the power supply circuit 24 or heat generation from the electromagnet 20 can be suppressed as much as possible. Note that the electromagnet 20 only needs to exert an electromagnetic attraction force that supports the spring characteristics of the elastic body 18.
For example, an electromagnet with a smaller capacity can be used than when obtaining the spring constant of the dynamic damper using only the electromagnet 20.

Further, in this embodiment, since the above planetary gear set 10 is used, when the gear ratio of this planetary gear set 10 is ρ, the force applied to the mass member 17 by the electromagnetic attraction force of the electromagnet 20 is as follows. 1/ of the power given to carrier 15
As a result, the electromagnetic attraction force of the electromagnet 20 can be set small.

Second Embodiment In the embodiment shown in FIG. 7, a dynamic damper is constructed by fixing a mass member 17 directly onto the axis of the propeller shaft 1 via an elastic body 18. 17, an electromagnet 20 similar to that of the first embodiment is incorporated. In this second embodiment as well, the electromagnet 20
The electromagnetic attractive force acts in parallel with and assists the spring characteristics of the elastic body 18, and these act as the spring constant of the dynamic damper.

In addition, in FIG. 7 showing the second embodiment, members that are considered to have the same or equivalent configuration as those in FIG. 1 of the first embodiment are designated by the same reference numerals in the drawing, and overlapping explanations of the configuration and operation will be omitted. .

(Effects of the invention) In this way, the present invention can transmit rotational fluctuations of the sun gear fixed to the main vibrating body to the ring gear and the mass member while being accelerated by the gear ratio of the planetary gear set. The moment of inertia of the dynamic damper can be amplified, and the damping effect of the dynamic damper based on the spring characteristics of the elastic body and the mass of the mass member can be enhanced. Moreover, in order to change the spring constant of the dynamic damper in accordance with the forced vibration frequency of the main vibrating body, the electromagnetic attractive force of the electromagnet, which is applied in parallel with the spring characteristic of the elastic body, also effectively performs the vibration damping function. In addition, the magnetic force of this electromagnet may be sufficient to merely assist the spring characteristics of the elastic body, so a small magnetic force is sufficient.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a cross-sectional view of a propeller shaft incorporating a dynamic damper, FIG. 2 is a cross-sectional view taken along the - line in FIG. 1, and FIG. 4 is a flowchart of the microcomputer in the control device, FIG. 5 is a mechanical schematic diagram of a general dynamic damper, and FIG. 6 is a characteristic diagram showing the frequency response curve of a dynamic damper. FIG. 7 is a sectional view showing the second embodiment in correspondence with FIG. 1. 17... Mass member, 18... Elastic body, 20...
Electromagnet, 40...control device.

Claims (1)

[Scope of utility model registration request] A sun gear of a planetary gear set fixed to a main vibrating body that generates forced vibration, a ring gear arranged via a plurality of pinions positioned by a carrier with respect to the sun gear, and a mass member fixed to the ring gear, an elastic body that exhibits a spring characteristic in a torsional direction due to relative rotation between the main vibrating body and the mass member;
Similarly, between the main vibrating body and the mass member, there is an electromagnet that exerts an electromagnetic attractive force in parallel with the spring characteristics of the elastic body, and the current value flowing through this electromagnet is proportional to the change in the forced frequency of the main vibrating body. A dynamic damper comprising a control device for increasing and decreasing the amount of the damper.