JP2839969B2 - How to correct wheel imbalance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting imbalance of a vehicle wheel.

[0002]

2. Description of the Related Art In general, an automobile wheel has an eccentric imbalance in a weight distribution around its axle.
If there is such an unbalance, vibration of the lower arm connected to the wheel occurs when the wheel rotates,
It is also known that the vibration is transmitted to a steering wheel connected to a wheel via a steering system, so that a circumferential vibration (so-called shimmy) of the steering wheel is generated.

For this reason, in an automobile manufacturing line or the like, a balance weight having a weight corresponding to the unbalance amount of the wheel (the eccentric weight of the wheel) is attached to a position corresponding to the unbalance position of the wheel. It tries to correct the wheel imbalance and thus the shimmy of the steering wheel.

[0004] In this case, with respect to the vibration of the lower arm or the like due to the unbalance of the wheel, as disclosed in, for example, JP-A-63-266331 by the present applicant, attention is paid particularly to the vibration of the lower arm in the front-rear direction. Then
The unbalance amount of the wheel is substantially proportional to the amplitude of the displacement waveform in the front-rear direction of the lower arm, and the unbalance position appears as the phase of the displacement waveform in the front-rear direction of the lower arm with respect to the rotation phase of the wheel.

Therefore, conventionally, when correcting the imbalance of the wheel, as disclosed in the same publication, the displacement of the lower arm in the front-rear direction while rotating the wheel is measured by an optical distance measuring device such as a laser range finder. The amount of unbalance of the wheel is determined from the amplitude of the detected displacement waveform by referring to a tuning chart previously obtained by experiment, and the unbalance amount of the wheel is determined from the phase of the displacement waveform with respect to the rotational phase of the wheel. I try to find the balance position. Then, a balance weight corresponding to the amount of unbalance is attached to a position corresponding to the unbalance position of the wheel, thereby correcting the unbalance of the wheel, and thereby reducing the shimmy of the steering wheel.

However, in such a conventional method, since the displacement of the lower arm in the front-rear direction is detected by the optical displacement detector, a reflector is attached to a predetermined portion of the lower arm and is opposed to the reflector. The light-emitting / light-receiving device must be arranged at a location, and their positional relationship must be set accurately and appropriately.

For this reason, when detecting the displacement of the lower arm, setting of the reflector and the light emitting / receiving device of the optical displacement detector takes a relatively long time, and it is necessary to correct the wheel imbalance and the shimmy of the steering wheel. This hindered the efficiency of the measurement work.

[0008]

SUMMARY OF THE INVENTION The present invention solves this inconvenience, corrects wheel imbalance accurately,
In addition, it is an object of the present invention to provide a method that can efficiently and easily perform the operation of correcting the shimmy of the handle in a short time.

[0009]

The vibration of the lower arm in the front-rear direction due to the unbalance of the wheel occurs sinusoidally in synchronization with the rotation of the wheel, and therefore corresponds to the second order differential value of the displacement of the lower arm in the front-rear direction. The lower arm acceleration also occurs sinusoidally in synchronization with the rotation of the wheel, and the amplitude of the acceleration waveform is proportional to the amplitude of the displacement of the lower arm,
The phase of the acceleration waveform coincides with the phase of the displacement waveform of the lower arm.

Therefore, if the longitudinal acceleration of the lower arm due to the unbalance of the wheel is detected, the unbalance amount and the unbalance position of the wheel can be obtained from the amplitude and phase of the acceleration waveform.

In this case, the vibration in the front-rear direction of the lower arm also includes harmonic components due to wheel imbalance, frequency components due to engine vibration, and the like. These unnecessary frequency components are removed by a filter or the like. Thus, a vibration waveform in the front-rear direction of the lower arm due to wheel imbalance can be obtained at the same frequency as the rotation frequency of the wheel.

Further, while rotating the left and right front wheels, which are the steered wheels of the automobile, at different rotational frequencies from each other,
When the circumferential acceleration of the steering wheel is detected, if there is an imbalance in each wheel, a frequency component of vibration corresponding to a difference between different rotational frequencies of both wheels is superimposed on the circumferential acceleration waveform of the steering wheel. The acceleration waveform in the circumferential direction of the handle is a vibration waveform accompanied by a beat.

In order to achieve the above object, the present invention provides a method for correcting imbalance between left and right wheels on the front side of an automobile, comprising the steps of: rotating the left and right wheels; Detecting the longitudinal acceleration of each of the left and right lower arms connected to each of the left and right wheels, and extracting a frequency component corresponding to the rotation frequency of the wheel to which the lower arm is connected from the detected acceleration of each of the lower arms Obtaining, for each lower arm, a vibration waveform of the acceleration of the lower arm resulting from imbalance of the wheel to which the lower arm is connected; and connecting the amplitude and phase of the vibration waveform of the acceleration of each lower arm to the lower arm. Acceleration for each lower arm as the amount of wheel unbalance and the amount corresponding to the unbalance position Correcting the imbalance of each wheel to which each lower arm is connected based on the amplitude and phase of the vibration waveform, and rotating both wheels at different rotational frequencies after correcting the imbalance of the left and right wheels Detecting the acceleration in the circumferential direction of the steering wheel of the vehicle when the wheels rotate, and determining whether the imbalance between the two wheels is corrected based on the detected amplitude waveform of the acceleration of the steering wheel. It is characterized by.

[0014]

According to the present invention, when correcting the left and right wheels on the front side of the vehicle, the front and rear accelerations of the lower arms connected to the respective wheels are detected while rotating the left and right wheels.

In this case, since the acceleration detected for each lower arm includes a frequency component due to engine vibration or the like, the acceleration detected for each lower arm corresponds to the rotation frequency of the wheel to which the lower arm is connected. By extracting the frequency component, a vibration waveform of the acceleration in the front-rear direction of the lower arm due to imbalance of the wheel to which the lower arm is connected is obtained for each lower arm.

The amplitude and phase of the vibration waveform of the acceleration of each lower arm correspond to the unbalance amount and the unbalance position of the wheel to which the lower arm is connected. It is possible to correct the balance, and this correction of the imbalance basically reduces the shimmy of the steering wheel of the motor vehicle.

Further, according to the present invention, after correcting the imbalance between the left and right wheels on the front side as described above, the acceleration in the circumferential direction of the steering wheel of the automobile is detected while rotating both wheels at different rotational frequencies. I do. At this time, if the unbalance of each wheel remains, the circumferential acceleration waveform of the steering wheel becomes a vibration waveform accompanied by a beat as described above, so that the shimmy of the steering wheel can be reliably determined based on the circumferential acceleration waveform of the steering wheel. It is possible to determine whether or not the correction result of the imbalance between the front wheels is correct, including whether or not it has been reduced.

Incidentally, in order to detect the longitudinal acceleration of the lower arm, an acceleration sensor or the like may be used.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory configuration diagram of a measurement system for correcting wheel imbalance and steering wheel shimmy by applying an example of the present invention, FIGS. 2 (a), (b) and FIG.
4 (a) and 4 (b) are diagrams for explaining a correction method by the measurement system, and FIGS. 4 (a) and 4 (b) illustrate the shimmy of the steering wheel and the acceleration of the lower arm after correction of wheel imbalance. FIG.

In FIG. 1, reference numeral 1 schematically shows the structure of a main part of an automobile. In the drawing, reference numerals 2L and 2R denote front left and right wheels of the automobile, and reference numeral 3 denotes a steering wheel. The handle 3 is connected to the wheels 2L and 2R via a steering shaft 4, a pinion 5, a tie rod 7 having a rack 6, and knuckle arms 8L and 8R, and the knuckle arms 8L and 8R.
Lower arms 9L, 9R for suspending the wheels 2L, 2R on a vehicle body (not shown) are respectively extended from connecting portions of the R and the wheels 2L, 2R.

In this case, the wheels 2L and 2R are respectively supported on a rotating drum (not shown), and are driven to rotate via the rotating drum.

The lower arms 9L and 9R are provided with acceleration sensors 10L and 10R for detecting the acceleration of the lower arms 9L and 9R in the front-rear direction (vehicle length direction), respectively. To the spectrum analyzer 1 via the amplifier 11
2 is input.

In this case, the spectrum analyzer 12
The function of analyzing the detection signals of the acceleration sensors 10L and 10R (hereinafter collectively referred to as the acceleration sensor 10 as necessary), and the wheels 2L and 10R from the detection signals of the acceleration sensors 10 based on the spectrum analysis. 2R
(Hereinafter, these are collectively referred to as wheels 2 as necessary)
And a function as a band-pass filter for extracting only the frequency component at the rotation frequency of..., And outputs the extracted acceleration signal to the data processing device 13.

An acceleration sensor 14 for detecting the acceleration in the circumferential direction is attached to the handle 3, and this acceleration sensor 14 inputs the detected acceleration signal to the spectrum analyzer 12 via the amplifier 15. .

The data processing device 13 is composed of a personal computer, a recorder, a display, and the like (not shown), and displays output signals from the spectrum analyzer 12 and the acceleration sensor 14 on a display or the like, or records the signals on the recorder or the like. I am trying to do it.

A phase detector 16 for detecting the rotational phase of each wheel 2 is provided on the side of each wheel 2.

In this case, each of the phase detectors 16 includes a photoelectric tube 17 provided to face the outer peripheral portion of each wheel 2 and a reflection tape 18 attached to a predetermined portion of the outer peripheral portion of each wheel 2. Is composed of
The photoelectric tube 17 holds the reflective tape 1 when each wheel 2 rotates.
8, that is, a pulse is output to the data processing device 13 at the rotation frequency of each wheel 2.

Next, a method of correcting the imbalance of each wheel 2 by using the measurement system will be described.

When correcting the imbalance of each wheel 2, each wheel 2 is rotated via a rotating drum (not shown).

At this time, if each wheel 2 is unbalanced, each of the lower arms 9L and 9R (hereinafter, these are collectively referred to as the lower arm 9 as necessary) vibrate in the front-rear direction,
The acceleration of these vibrations is detected by each acceleration sensor 10.

In this case, the detection signal of each acceleration sensor 10 is substantially periodic, for example, as shown in FIG. 2A, but has a distorted waveform.

At this time, the vibration of each lower arm 9 is transmitted to the handle 3, the handle 3 vibrates in the circumferential direction, and the acceleration of the vibration is detected by the acceleration sensor 14.

In this case, for example, if a slight rotational speed difference is given to each wheel 2, the frequency component of the vibration corresponding to the rotational frequency difference is superimposed on the circumferential vibration of the steering wheel 3, and the acceleration sensor 14 detects the frequency component. The signal is, for example, as shown in FIG.
As shown in FIG.

Then, the spectrum analyzer 12
Receives the detection signal of the acceleration sensor 10 of each lower arm 9, analyzes the spectrum, and further, based on the spectrum data, detects the frequency component of the detection signal of each acceleration sensor 10 at the rotation frequency of each wheel 2. ,
That is, only the frequency component due to the imbalance of each wheel 2 is extracted.

More specifically, for example, when spectrum analysis is performed on the vibration waveform of the acceleration shown in FIG. 2A, the spectrum data shown in FIG. 3A is obtained.

As shown in FIG. 3A, although various frequency components are mixed in the detection signal of each acceleration sensor 10, large spectra S1 to S3 are observed at three frequencies f1 to f3. Spectra S1 to S3
Of these, spectrum S1 is a primary frequency component (a component at the rotation frequency of each wheel 2) due to imbalance of each wheel 2, spectrum S2 is due to engine vibration, and spectrum S3 is a harmonic component due to imbalance of each wheel 2. It is.

Therefore, if only the component at the frequency f1 (rotation frequency of each wheel 2) is extracted from the detection signal of each acceleration sensor 10, the acceleration waveform of the vibration of the lower arm 9 due to the unbalance of each wheel 2 can be obtained. .

Therefore, the spectrum analyzer 12 uses the function as a bandpass filter to detect the frequency f1 (each wheel 2
Of the rotation frequency) and outputs this to the data processing device 13.

In this case, the acceleration waveform in the front-rear direction of each lower arm 9 due to the unbalance of each wheel 2 becomes, for example, a substantially sinusoidal smooth waveform as shown in FIG. And, as mentioned above, this acceleration waveform is
Since this is equivalent to the second derivative of the longitudinal displacement of each lower arm 9 due to the unbalance of each wheel 2,
The amplitude and the phase are amounts corresponding to the unbalance amount of each wheel 2 (the eccentric weight of each wheel 2) and the unbalance position.

On the other hand, the data processing device 13 outputs the signal from the photoelectric tube 17 of each phase detector 16 every one rotation of each wheel 2, that is, at the rotation frequency of each wheel 2, as shown in FIG.
As shown in (b) together with the acceleration waveform, the reference pulse P is received.

Then, the data processing device 13 compares the acceleration waveform in the front-rear direction of each lower arm 9 received from the spectrum analyzer 12 with the reference pulse P received from each phase detector 16 to obtain the data shown in FIG. As shown in ()), the phase angle φ of the acceleration waveform in the front-rear direction of each lower arm 9 with respect to the reference pulse P is obtained, the amplitude A of the acceleration waveform is obtained, and this is output to a recorder, a display (not shown), or the like.

After the amplitude A and the phase angle φ of the acceleration in the front-rear direction of each lower arm 9 are obtained in this manner, the wheel 2 can be obtained from the amplitude A based on a tuning chart or the like previously obtained by experiments. The amount of unbalance is calculated every time, and the unbalance position is calculated from the phase angle φ.

In this case, the method of obtaining the unbalance amount and the unbalance position of each wheel 2 is basically the same as the method disclosed by the present applicant in Japanese Patent Application Laid-Open No. 63-266331. The position is determined by each phase detector 1
4 is determined as a position moved in the circumferential direction of each wheel 2 by an angle obtained by adding a correction angle determined in advance by an experiment or the like to the phase angle φ with reference to the mounting position of the reflection tape 16 on each wheel 2. .

After the amount of unbalance and the position of the unbalance of each wheel 2 are determined in this manner, each wheel 2
Is temporarily stopped, and in this state, for each wheel 2, a balance weight having a weight corresponding to the amount of unbalance is attached to a position corresponding to the unbalance position, whereby the unbalance of each wheel 2 is reduced. Will be modified.

Then, after such correction, while rotating each wheel 2 again, the acceleration in the circumferential direction of the steering wheel 3 is detected via the acceleration sensor 14, and among the longitudinal accelerations of the lower arms 9, The rotational frequency component of the wheel 2 is detected via each of the acceleration sensors 10 and the spectrum analyzer 12.

In this case, the waveform of the circumferential acceleration of the steering wheel 3 and the waveform of the rotational frequency component of each wheel 2 in the longitudinal acceleration of each lower arm 9 are, for example, shown in FIG. The waveform is as shown in FIG.

Then, based on these acceleration waveforms, the quality of the correction result of the imbalance of each wheel 2 is determined.

That is, if the amplitude of these acceleration waveforms is equal to or less than a predetermined reference value, each wheel 2
Is correctly corrected, and the shimmy of the steering wheel 3 is satisfactorily corrected by the correction.

Conversely, when the amplitude of these acceleration waveforms exceeds a predetermined reference value, each wheel 2
Was improperly corrected, or the imbalance of each wheel 2 was corrected, but the shimmy of the steering wheel 3 was not resolved.
In this case, for example, each wheel 2 is replaced with another wheel, and the above-mentioned work of correcting imbalance is performed again.

As a result, the imbalance of each wheel 2 is reliably corrected, and the shimmy of the steering wheel 3 is also reliably corrected.

[0051]

As is apparent from the above description, according to the present invention, the longitudinal acceleration of each of the left and right lower arms is detected while rotating the left and right wheels on the front side of the automobile, and each of the lower arms is detected. From each of the detected accelerations, a frequency component corresponding to the rotation frequency of the wheel to which the lower arm is connected is extracted, and the amplitude and phase of the extracted vibration waveform of the acceleration of each lower arm are connected to the lower arm. Since the imbalance of each wheel is corrected as an amount corresponding to the unbalance amount and the unbalance position of the wheel, the acceleration sensor and the like are attached to each lower arm during the work, and the acceleration waveform obtained from the acceleration sensor is analyzed. To properly correct the wheel imbalance and thus the steering wheel shimmy It can also be carried out easily and efficiently measuring operations, etc. for the modification in a short time.

Further, according to the present invention, after correcting the imbalance between both wheels on the front side of the vehicle as described above, while rotating both wheels at different rotational frequencies,
The acceleration in the circumferential direction of the steering wheel of the car is detected, and the quality of the correction of the imbalance between the two wheels is judged based on the detected amplitude waveform of the acceleration of the steering wheel. It is possible to reliably determine whether the balance is correct or not.
It is possible to secure certainty of correcting the wheel imbalance.

[Brief description of the drawings]

FIG. 1 is an explanatory configuration diagram of a measurement system for correcting wheel imbalance and steering wheel shimmy by applying an example of the present invention;

FIG. 2 is a diagram for explaining a correction method by the measurement system;

FIG. 3 is a diagram for explaining a correction method by the measurement system;

FIG. 4 is a diagram exemplarily showing acceleration of a shimmy of a steering wheel and a lower arm after correction of wheel imbalance;

[Explanation of symbols]

2L, 2R: Wheel, 3: Handle, 9L, 9R: Lower arm.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01M 1/16 G01M 1/32

Claims (1)

(57) [Claims] 1. A method for modifying unbalance of the left and right wheels of the front of a motor vehicle, comprising the steps of rotating each wheel of the right and left, to the wheel of the right and left at the rotary
A step of detecting each of acceleration in the longitudinal direction of the lower arm of the left and right respectively connected, each detected lower arm
From the acceleration extracts a frequency component corresponding to the rotation frequency of the wheel to which the lower arm is connected, each Roaa
For each arm, and obtaining a vibration waveform of acceleration of the lower arm caused by the unbalance of the wheel to which the lower arm is connected, the amplitude and phase of the vibration waveform of the acceleration of each lower arm is the lower arm are connected Correcting the unbalance of each wheel to which each lower arm is connected based on the amplitude and phase of the vibration waveform of the acceleration of each lower arm as the amount corresponding to the wheel unbalance amount and the unbalance position ; Invar for each wheel
After the lance is corrected, the wheels must be at different rotational frequencies.
Rotating the wheels, and when the wheels rotate,
Detecting a circumferential acceleration of the steering wheel of the vehicle;
Both wheels are based on the amplitude waveform of the detected acceleration of the steering wheel.
Determining whether the correction of the unbalance of the wheel is good or bad .