JPH049454B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for detecting imbalance in the running state of wheels of an automobile or the like. (Prior Art) Conventionally, as a so-called "on-the-car" detection method for detecting unbalance of a wheel while it is attached to the body of a car, for example,
The one described in Publication No. 4402 is known. In this system, the lower arm is jacked up via a vibration detector, and a vibration detector is also placed in contact with the back of the brake support plate to detect vibrations in the vertical direction of the wheel and around the axis of the king pin. . (Problems to be Solved by the Invention) In the conventional method described above, it is necessary to raise and lower the vehicle body each time a measurement is made, and the contact positions of the lower arm of the vibration detector and the brake against the support plate are always the same. If the position is not adjusted, the detected value will change.
There was an inconvenience that it was not possible to correct the imbalance accurately. SUMMARY OF THE INVENTION An object of the present invention is to provide a wheel unbalance detection method that does not have such conventional disadvantages. (Means for explaining the problem) The present invention is a method for detecting unbalance of wheels attached to a vehicle body such as an automobile, in which the wheels are placed on a rotating drum, and the wheels are rotated at a constant speed. The present invention is characterized in that the amount of displacement of an unsprung component other than a rotating wheel in at least the vertical direction and the wheel turning angle direction is detected in a non-contact manner. (Example) Hereinafter, an example of the present invention will be described with reference to the drawings. In the drawing, 1 is a wheel attached to a vehicle body 2 of an automobile, etc., 3 is a rotating drum rotated by a driving motor or by the driving force of an automobile, etc. via the wheel 1, 4 is a non-contact displacement meter, and 5 is a rotating drum. 6 indicates a small articulated robot for installing the non-contact displacement meter 4 at a predetermined position, and 6 indicates a position detector consisting of a light emitting element and a light receiving element and detecting the unbalanced position of the wheel 1. The non-contact displacement meter 4 is, for example, a commercially available non-contact optical displacement meter, and as shown in FIG. It consists of a condensing lens 8 for providing a bright spot, a lens 9 for condensing scattered light generated on the surface of the object Bd, and a photo-sensing element 10 placed at the condensing point position and reacting to the bright spot position. The change in the position of the surface of the object to be measured Bd shown in FIGS. 3A and 3B is extracted as a change in the bright spot position on the photo-sensing element 10, and the displacement of the object to be measured is measured. Next, the present unbalance detection method will be explained. The unbalance of the wheel 1 includes (a) static unbalance, which is an unbalanced load in the circumferential direction of the wheel including drive system and braking system unbalance, (b) dynamic unbalance, which is an unbalanced load in the width direction of the wheel, ( c) Uniform unbalance in which the spring constant is uniform in the circumferential or width direction of the tire, and (d) unbalance due to fluctuations in the outer diameter of the tire. Uniformity imbalance includes the variation in force in the tire's radial direction (radial force variation, RFV) and the variation in force in the tire's width direction (lateral force variation, RFV).
Variation LFV). If there is an imbalance in the wheel as described in (a), (b), (c), or (d) above, the wheel rotating at a constant speed will cause vertical vibration, longitudinal vibration, and turning angle direction as shown in Table 1. Vibrate one of these vibrations or a combination of some of them.

[Table] In this proposal, the vibration in the steering angle direction of the wheel 1 is
As shown in FIGS. 2 and 2, the displacement meter 4 is set by the robot 5 to face, for example, the surface of the splash guard 11, and the amount of displacement in the direction of the cutting angle of the surface is measured by making the infrared rays perpendicularly incident on the surface. Detect by measurement. The vertical and longitudinal vibrations of the wheel 1 can be measured by moving the displacement meter 4 to the lower surface and front surface (or rear surface) of the lower arm 12 by means of the robot 5, for example, as shown by the arrows in FIGS. 1 and 2. Detection is performed by making the infrared rays incident perpendicularly and measuring the amount of displacement in the vertical and longitudinal directions of the surface. Now, when the wheel 1 attached to the vehicle body 2 is placed on the rotating drum 3 with another wheel (not shown) clamped by a tire clamp device, and the wheel 1 is rotated at a constant speed, the wheel 1 is exposed. Assume that the vibration occurs only in the direction of the turning angle, as shown in "A" of 2. The amount of displacement corresponding to the vibration is measured from the output of the displacement meter 4 placed at the above position. The vibration is caused by an unbalance in the width direction of the wheel 1, and the relationship between the weight and the displacement amount corresponding to the unbalance amount is made into a chart in advance or stored in a memory, and the chart or The weight amount corresponding to the measured displacement amount is determined from the contents of the memory. A reflective tape is attached to an arbitrary position on the wheel 1, and a position detector 6 is placed at a position where the tape passes when the wheel 1 rotates. The light reflected from the light emitting element is incident on the light receiving element of the position detector 6 every time the tape passes when the wheel 1 rotates, and a pulse signal is output from the element. Therefore, this pulse signal and displacement meter 4
The unbalanced position of the wheel 1 is determined from the phase difference between the two by comparing the position displacement signals output from the two. Next, as shown in the block diagram of FIG. 4, a weight corresponding to the amount of unbalance is attached to the unbalanced position of the rim of wheel 1 to correct dynamic unbalance, which is one of the unbalances in the width direction of wheel 1. Do this. When the wheel 1 is rotated again after the correction, if the vibration is not detected, the test passes the dynamic balancing, but if the vibration is still detected, as is clear from Table 1, the LFV is the cause. If the problem cannot be fixed, replace the tire.

[Table] Next, assume that the wheel 1 vibrates vertically and in the direction of the turning angle (“B” in Table 2, × vibrates, ○ does not vibrate.) Measure the amount of displacement in the direction. From this displacement amount, the unbalance amount is determined in the same manner as above. One of the causes of the unbalance is a change in the outer diameter of the tire as shown in Table 1, so it is corrected by changing the mounting position of the tire on the rim. If the vertical vibration remains as before after the correction, the RFV is the cause, so replace the tire as it cannot be corrected. After the above correction, when the vertical vibration disappears, the amount of unbalance in the width direction of the wheel 1 is determined from the amount of displacement in the turning angle direction measured by the displacement meter 4 placed at the above position. Find the weight. Next, a weight corresponding to this unbalance amount is attached to the unbalanced position of the rim of the wheel 1 to correct the dynamic balance. If vibration in the same direction remains even after correction, the LFV is the cause, so replace the tire as it cannot be corrected. It is also assumed that the wheel 1 vibrates vertically and longitudinally ("C" in Table 2). The amount of displacement in the vertical direction and the front-back direction is measured from the amount of displacement 4 arranged respectively above and in the above-mentioned position. A weight corresponding to the static unbalance amount is determined from both displacement amounts in the same manner as described above. Next, a weight corresponding to the amount of static unbalance is attached to the unbalanced position of the rim of the wheel 1 to perform static balancing. If the vertical vibration still remains after correction, it is assumed that there is a change in the outer diameter of the tire, and correction is made by changing the mounting position of the tire relative to the rim. If the vertical vibration still remains, the RFV is the cause, so replace the tire as something that cannot be corrected. Assume that the wheel 1 vibrates vertically, longitudinally, and in the direction of the turning angle (“D” in Table 2).As in the case of “C” in Table 2, the displacement gauges 4 placed at the above positions and . The amount of static unbalance is determined from each output, and a weight corresponding to the amount of unbalance is attached to the unbalanced position of the rim of the wheel 1 to perform static balancing. If the vertical vibration still remains after the correction, perform the correction using the same procedure as in case "C" above. After the correction, when the vertical vibration and longitudinal vibration are gone, calculate the weight according to the amount of unbalance in the width direction of the wheel 1 from the amount of displacement in the turning angle direction obtained by the displacement meter 4 placed at the above position. demand. Next, a weight corresponding to this amount of unbalance is attached to the unbalanced position of the rim of the wheel 1 to correct the dynamic unbalance. If the vibration in the same direction still remains after correction, the LFV is the cause, so replace the tire as it cannot be corrected. (Effects of the Invention) According to the present invention, it is possible to detect the unbalance of the wheels attached to the body of the vehicle without jacking up the body of the vehicle, so the unbalance can be detected in a short time and with less effort. This has the effect that the balance amount can always be detected with high accuracy.

[Brief explanation of drawings]

Figures 1 and 2 are a front view and a view taken along the line A-A in Figure 1, and Figures A and B are non-contact views when the object to be measured is displaced. FIG. 4 is an explanatory diagram of the operation of one example of the type displacement meter, and is a flowchart of unbalance correction by the present unbalance detection method. 1...Wheel, 2...Car body, 3...Rotating drum,
4...Non-contact displacement meter, 5...Robot, 6...
Position detector, 11...Splash guard, 12
...Lower arm.

Claims (1)

[Claims] 1. In a method for detecting unbalance of a wheel attached to a vehicle body such as an automobile, the wheel is placed on a rotating drum, the wheel is rotated at a constant speed, and at least one of the unsprung components other than the rotating wheel is detected. A method for detecting unbalance of wheels of automobiles, etc., characterized by detecting displacement in the vertical direction and wheel turning angle direction in a non-contact manner.