JPS6035618A - Suspension system - Google Patents

Abstract

PURPOSE:To keep off a noise inside a car room due to vibrations in a rear wheel, by detecting acceleration to be added to a front wheel, while constituting this acceleration and exciting force in the same direction so as to be added to the rear wheel after the elapse of time in response to a car speed. CONSTITUTION:When a front wheel 12 runs on a projection P on a road surface and thereby exciting force acts thereon, this impact is detected by an acceleration sensor 15 and inputted into a control part 16. Simultaneously a car speed is detected and inputted in this control part 16 which performs the specified operation on the basis of the acceleration information 25, determines a damping subject and compensates it so as to accord with an automobile characteristic, while the control part 16 calculates the time required for running on the projection P by a rear wheel 13 being found from the car speed. And, on the basis of these data, the control part 16 drives an excitor 25 in order to pull up the rear wheel 13. With this constitution, a variation due to the projection P can be prevented from causing it to act on the rear wheel 13, thus a noise insides a car room can be kept back.

Description

[Detailed description of the invention] (Technical bone!! The present invention relates to a suspension system that prevents vibrations from being input to rear wheels by applying vibrations.

(Prior Art) As a conventional suspension system, one shown in FIG. 1, for example, is known. As shown in the figure, this suspension system has a shock absorber 2 interposed between a vehicle body 1 and wheels (not shown) to damp vibrations of the wheels.

The shock absorber 2 has a cylindrical portion 2a and a rond portion 2b that are displaced relative to each other as the wheel vibrates.The cylindrical portion 2a is connected to the wheel, and the rond portion 2b is connected to the vehicle body 1. That is, a bracket 3 is fixed to the upper end of the rond part 2b, and the bracket 3 is attached to the vehicle body 1 via an elastic body 4. Further, a spring receiving seat 5 is provided on the cylindrical portion 2a, and a spring 6 is compressed between the spring receiving seat 5 and the bracket 3.

In such a suspension system, vibrations generated by the wheels are damped by shock absorbers 2 and buffered by springs 6.

However, in such a suspension system, the dynamic spring constant of the vibration system composed of the shock absorber 2, the elastic body 4, and the spring 6 is mainly intended to prevent vibrations in the low frequency range from being transmitted to the vehicle body. Since the high frequency range (301
There was a drawback that vibrations (around 1Z to 10011Z) were easily transmitted to the vehicle body, and noise was generated in the vehicle interior.

In other words, as shown in Fig. 5, when a wheel rides on a protrusion on the road surface and an excitation force is applied to the wheel, the wheel vibrates due to the elasticity of the tire's trend section or side wall section. As a result, vibrations in the range of 8011z to 9011z, called shocking, and vibrations in the range of 40 fiz to 5011z, called drumming, are transmitted to the vehicle body, making it difficult to maintain quietness in the vehicle interior.

(Object of the Invention) This invention was made in view of the above-mentioned drawbacks, and when the front wheel rides on a protrusion on the road surface and an excitation force is applied, the rear wheel also follows the same trajectory as the front wheel. It is estimated that the vehicle will run over the protrusion, and an excitation force in the same direction as the excitation force applied to the front wheel will be applied to the rear wheel after a period of time corresponding to the vehicle speed has elapsed to reduce the noise inside the vehicle caused by the vibration of the rear wheel. The purpose is to prevent this from occurring.

(Structure of the Invention) The suspension system according to the present invention includes a vehicle speed detection means for detecting vehicle speed, an acceleration detection means for detecting acceleration applied to the front wheels, and an excitation means for applying an excitation force to the rear wheels. control means for controlling the vibration excitation means based on the output signals of the third vehicle speed detection means and the acceleration detection means, and when acceleration is applied to the front wheels, the rear wheels are activated after a period of time corresponding to the vehicle speed has elapsed. This applies an excitation force that acts in the same direction as the acceleration to the front wheels.

According to this suspension system, when the rear wheel rides on the protrusion after the front wheel rides on the protrusion, vibration is applied in the same direction as the excitation force in response to the force exerted by riding on the protrusion. Since the force is applied to the rear wheels, it is possible to reduce vibrations caused by the rear wheels, and it is possible to improve the quietness in the vehicle interior.

(Example) The present invention will be explained below based on the drawings.

2 to 4 are diagrams showing an embodiment of the present invention, in which FIG. 2 is a schematic overall configuration diagram, FIG. 3 is a sectional view of the waist, and FIG. 4 is a block diagram.

First, to explain the configuration, in FIG. 2, 11 is a vehicle body, 12 is a front wheel supported by the vehicle body II via a shock absorber 14F, and 13 is a rear wheel supported by the vehicle body 11 via a shock absorber 14R. It shows. An acceleration sensor (acceleration detection means) 15 for detecting vertical acceleration applied to the front wheel 12 is installed on the front wheel 12, and the acceleration sensor 15 is connected to a control unit 16 mounted on the vehicle body. There is. Further, a vibration excitation means 25 is provided between the shock absorber 14R of the rear wheel 13 and the vehicle body 11.

The shock absorber 14R interposed between the rear wheel 13 and the vehicle body 11 is, for example, a well-known cylindrical type.
It has a cylindrical body connected to the rear wheel 13 and a mouth/nod inserted into the cylindrical body so as to be relatively displaceable, and this rod is supported by the vehicle body 11 via an excitation means. That is, the third
As shown in the figure, a placket is fixed to the mouth/throat 17 of the shock absorber 14R with a nut 19, and an extension rod 17a extending upward is integrally formed. A disk 21 consisting of monthly charges is fixed. The bracket 1-18 and the vehicle body 11 are provided with an insulator 2 made of a rubber-like elastic material.
0 is fixed to connect the bracket 18, that is, the shock absorber 14R and the vehicle body 1, allowing relative displacement. Further, a solenoid case 22 having an annular groove 22 a is fixed to the vehicle body 11 with bolts 23 . This solenoid case 22 includes a pair of solenoids 24a, 24. arranged vertically and connected to the control unit 16. b is accommodated, and a disk 21 is loosely inserted into the annular m22a so as to be vertically displaceable. This disk 21 is connected to the solenoid 24
a and 24b to apply an excitation force that acts in the vertical direction. These disks 21 and solenoids 24a and 24b constitute a vibrating means 25.

Control unit <control means> xs has a configuration as shown in the block diagram of FIG. 4. That is,
The control unit 16 converts the analog [-Xa(L) output from the acceleration sensor I5 into a digital signal X (t)
, a reference signal generator 27 that generates the digital base 11ji signal y (t) for setting the tolerance range, and an output signal x (t) of the A/D converter 26 .
t) and the output signal Y (t) of the reference signal generator 27 are Fourier-transformed in order to specify the frequency domain and converted into frequency-domain signals Sx (f) and Sy (f) (Fig. 5), respectively. The ratio H(f) (f) of the output signal Sx (f), S)' (f) of the Fourier transformer
Calculate H(f) = Sx (f) /Sy (f)) and output signals Sx (f) and Sy (f) only when the ratio H(f) is greater than a predetermined value a (for example, a-1). comparator 2
9, and the signal Sy (f) is subtracted from the signal Sx (f) to calculate the vibration component exceeding the allowable range (the shaded area in Figure 5), and the signal Sz (t) (Sz (f) = S
a subtracter 30 that outputs x (f)-3V (f));
Characteristics of shock absorber 14 or solenoid 24
The signal Sw (f) (Sw (
f) = S'z, (f) an inverse Fourier transformer 32; a phase inverter 35 that inverts the phase of the output signal W (t) of the inverse Fourier transformer 32;
a divider 34 which receives the output signal V of the vehicle speed sensor 33 and calculates a delay time corresponding to the wheel base L;
Output signal W (t) of phase inverter N35 and divider 34
an adder 36 that receives the output signal δ and performs time correction;
The output signal W(t+δ) of the adder 36 is converted into an analog signal V<
t+δ), and the solenoid 24 based on the output signal V(t+δ) of the D/A converter 37.
and a driver 38 that selectively energizes.

Next, the effect will be explained.

When the front wheel 12 passes over the protrusion P while the vehicle is running at vehicle speed ■, an excitation force acts on the front wheel 12, causing it to vibrate, and the acceleration sensor 15 detects the vibration of the front wheel 12 and outputs a signal Xa.
(t) is output to the control unit 16. At the same time, the vehicle speed sensor 33 detects the vehicle speed V of the vehicle and outputs a signal V to the control unit 16.

In the control unit 16, the acceleration sensor I
5 and the output signal Y (t) of the reference signal generator 27 are Fourier-transformed by the Fourier transformer 28 to produce a frequency-domain signal Sx (
f), sy (f), and these signals 3x (f),
Sy (f) is compared by the comparator 29 to obtain a ratio H(f);
The following process is executed only when Sx (f)/5y(f) is equal to or greater than the predetermined value 3 (the shaded area in FIG. 5). However, when the ratio H(f) is greater than or equal to the predetermined value 3, the subtracter 30 calculates the difference 5z(f)(S
z (f)=Sx (f)-sy (f)l is calculated to identify the vibration component to be damped as shown in the shaded area in FIG. After performing correction to match the vehicle characteristics, the inverse Fourier transformer 32 performs inverse Fourier transform to convert the signal W (t) in the time domain, and the phase inversion 535 changes the phase of the signal W (t). is inverted and a signal W (t) is output. On the other hand, the divider 34 calculates the time from when the front wheel 12 rides on the protrusion p until the rear wheel 13 rides on the protrusion p based on the internally stored wheel base L and the output signal ■ of the vehicle speed sensor 33. , is output as a signal δ.

Then, the adder 36 determines the direction and time of excitation based on the output signal δ of the divider 34 and the output signal W (t) of the phase inverter 35, and the D/A converter 37 determines the analog signal V( t+δ) and output to the driver 38. The driver 38 energizes one of the solenoids 24a124b for a predetermined time based on the input signal V(t+δ). Therefore, the excitation means 25 applies an excitation force to the shock absorber 14R, and this excitation force is transmitted to the rear wheel 13. This excitation force is transmitted to the rear wheel 13 when the rear axle 13 rides on the protrusion p, and acts to pull up the rod 17. Further, the excitation force acts in the same direction as the excitation force applied to the rear wheel 13 when the rear wheel 13 rides on the protrusion p, and furthermore, the excitation force is applied when the rear wheel 13 rides on the protrusion p. Since it corresponds to the frequency generated due to the force, the excitation force when the rear wheel 13 rides on the protrusion p is not input to the rear wheel 13. That is, the control unit 16 assumes that when the rear wheel 13 runs onto the protrusion p, an excitation force that is approximately the same as the excitation force that was applied when the front wheel 12 ran onto the protrusion p is applied. Then, the excitation means 25 is driven, and an excitation force is applied to the rear wheel 13 via the shock absorber 14R so as to avoid the input of the assumed excitation force. Therefore, rear wheel 1
3 rides on a protrusion p or the like and an excitation force is applied, no vibration is input to the rear wheel 13, and noise is generated in the vehicle interior due to the vibration of the rear wheel 13. Since this does not occur, quietness in the vehicle interior is maintained.

(Effects of the Invention) As described above, according to the suspension system of the present invention, when the rear wheel runs onto a protrusion, the vibration means is operated to pull up the rear wheel, so vibration input from the road surface is used. Therefore, the noise inside the vehicle interior caused by the vibration of the wheels is reduced, and the quietness inside the vehicle interior is maintained satisfactorily.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the main parts of a conventional suspension system. 2 to 5 are diagrams showing a suspension system according to an embodiment of the present invention, in which FIG. 2 is an overall configuration diagram, FIG. 3 is a sectional view showing main parts, and FIG. 4 is a diagram showing a control means. Block diagram shown, No. 5
The figure shows the allocation characteristics. 11--Vehicle body, 12--Front wheel, 13--Rear wheel, 15--Acceleration sensor (acceleration detection means), 16-
・-・-Control unit-(?1ill In
means), 6...-excitation means. Patent Applicant Nissan Motor Co., Ltd. Representative Patent Attorney Ugagun Part Figure 1 Figure 2 1 Figure 3

Claims (1)

[Claims] A vehicle speed detection means for detecting the vehicle speed, an acceleration detection means for detecting acceleration applied to the front wheels, an excitation means for applying an excitation force to the rear wheels, and based on output signals of the vehicle speed detection means and the acceleration detection means. and control means for controlling the vibration excitation means, and when acceleration is applied to the front wheels, the vibration excitation means acts in the same direction in response to the acceleration applied to the front wheels after a time period corresponding to the vehicle speed has elapsed. A suspension system that applies an excitation force to the rear wheels and prevents vibration input from the road surface to the rear wheels.