JPH03262716A - Tire abnormality judging device - Google Patents

Abstract

PURPOSE:To always and certainly detect tire abnormality by judging a tire to be abnormal when the detected value regarding the surface temperature of the tire is larger than the specified threshold and also varying the threshold according to the variation of the distance between the surface of the tire and a tire temperature sensor. CONSTITUTION:The surface temperature of the front, rear, right, and left tires of a vehicle are detected by sensors 2 (2FL to 2RR). When the detected value of each sensor 2 is larger than the specified threshold, it is judged by an abnormality judging means 4 that the surface temperature of the tire is raised abnormally. Based on the result of this abnormality judgment, lamps or buzzers are operated for alarming the abnormality to the driver or the like by an alarm means 6. While, the distance between the surface of a tread and each sensor 2 is detected by a distance detecting means 8. In addition, based on the detected distance between the surface of the tire and the sensor, the threshold is changed by a threshold changing means 10. By this constitution, the abnormality of the tire is always and certainly detected regardless of the variation of the distance between the tire and sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a tire abnormality determination device that detects tire abnormalities such as the risk of bursting based on the tire surface temperature.

(Prior Art) When the air pressure of a tire decreases due to banking or the like while a car is running, the surface temperature of the tire increases abnormally. In view of this point, for example, the patent application No. 1-5 filed by the present applicant
As described in the No. 3514 application, a temperature sensor is used to measure the surface temperature of a tire, and an abnormal increase in the tire surface temperature is detected from the measured value. It is being considered to detect the risk of tire burst due to an abnormality.

As a specific example of such a tire abnormality detection system based on the tire surface temperature, for example, the tire surface temperature while a car is running, especially the tread surface temperature, is detected by a temperature sensor, and the detected temperature is set at a predetermined temperature. If the threshold value is exceeded, it may be determined that the surface temperature of the tire has increased abnormally and there is a tire abnormality such as a risk of tire burst, and a warning may be issued.

In addition, when detecting the tire surface temperature using a temperature sensor as described above, for example, a radiant heat absorption type (infrared absorption type) temperature sensor as described in the above-mentioned earlier application is used, and the temperature sensor is It is conceivable to attach it to the vehicle body side, for example, to the wheel house, facing the tread surface of the vehicle.

(Problem to be Solved by the Invention) However, when the above configuration is adopted, the tires move up and down with respect to the vehicle body via the suspension, or the front wheels (in the case of four-wheel steering, the rear wheels The tires in this vehicle are steered by steering wheel operation, and when such vertical movement or steering of the tires occurs, the distance between the tire surface and a temperature sensor attached to the vehicle body changes.

When the distance between the tire surface and the temperature sensor changes, the radiant heat attenuates over distance, so the output of the radiant heat absorption type temperature sensor changes, and especially when the distance becomes short, the output increases. As a result, the apparent upper temperature increases, and as a result, the tire is erroneously determined to be abnormal even though it is normal, resulting in a problem that the reliability of abnormality determination decreases.

In view of the above circumstances, an object of the present invention is to provide a tire abnormality determination device that can avoid erroneous determinations due to distance fluctuations between the tire surface and a tire temperature sensor and perform highly reliable tire abnormality determination. There is a particular thing.

(Means for Solving the Problems) In order to achieve the above object, the tire abnormality determination device according to the first invention of the present application includes a tire temperature sensor that detects the surface temperature of a tire, and a tire surface detected by the sensor. abnormality determining means for determining whether or not the tire is abnormal based on temperature and a predetermined threshold; distance detecting means for detecting the distance between the tire surface and the tire temperature sensor; and the detecting means and threshold value changing means for changing the threshold value based on the distance detected by.

In order to achieve the above object, the tire abnormality determination device according to the second invention of the present application includes a tire temperature sensor that detects the surface temperature of the tire, and a tire abnormality determination device based on the tire surface temperature detected by the sensor. an abnormality determination means for determining whether or not;
distance detection means for detecting the distance between the surface of the tire and the tire temperature sensor; and prohibition means for prohibiting determination that the tire is abnormal when the distance detected by the detection means is outside a predetermined range. It is characterized by comprising the following.

(Function) In the first invention, the threshold value, which is a criterion for determining whether or not there is an abnormality, is changed depending on the distance between the tire and the sensor. Therefore, even if the output value of the temperature sensor itself includes a change due to the distance between the tire and sensor, the change can be corrected by changing the threshold value based on the distance between the tire and sensor when determining an abnormality. Therefore, it is possible to perform a highly reliable abnormality determination that is not affected by changes in the distance between the tire and the sensor.

In the second invention, it is possible to determine that the tire is abnormal only when the distance between the tire and the sensor is within a predetermined range, and prohibit the determination that the tire is abnormal when it is outside the predetermined range. It is configured as follows. For example, when determining that a tire is abnormal when the detected temperature exceeds a preset threshold as described above, that threshold is the temperature of the tire when the tire is in its most normal condition.・
It is set based on the distance between sensors. Therefore, if the distance between the tire and sensor becomes much smaller than the value used as the basis for determining the threshold value, the detected value will also be much larger than the true tire surface temperature, and as a result, the tire A situation may occur in which an error is determined to be abnormal even though there is no abnormality.

However, in the second aspect of the invention, when the distance between the tire and the sensor is outside the predetermined range, it is prohibited to determine that the tire is abnormal, so the predetermined range is not properly determined. In other words, for example, the distance between the tire and the sensor, which was the standard for determining the above threshold value, is set as a range that is a predetermined distance shorter than the distance between the tire and the sensor, which is the standard for determining the above threshold. By setting distances that are significantly shorter than the distance between the tires and the sensor outside the predetermined range, it is possible to avoid the above-mentioned erroneous judgment due to the distance between the tire and the sensor becoming too short, and it is possible to determine a tire abnormality with high reliability. .

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, an embodiment of the first invention will be described.

FIG. 1 is a block diagram showing an embodiment of the first invention. The illustrated embodiment includes tire temperature sensors 2FL, 2FR, and 2R that detect the surface temperature of each of the front, rear, left, and right tires.
L, 2RR, and the surface temperature of each tire input from the tire temperature sensor are compared with a predetermined threshold. If the surface temperature of the tire is higher than the threshold, the surface temperature of that tire is abnormal. An abnormality determining means 4 that determines that the tire is rising, that is, that the tire is abnormal; and an alarm means 6 such as a lamp or a buzzer that issues a warning to the driver etc. upon receiving a determination by the abnormality determining means 4 that the tire is abnormal. and distance detection means 8 for detecting the distance between the tire tread surface and the tire temperature sensor (tire-sensor distance), and the above-mentioned distance detection means 8 according to the tire-sensor distance detected by the detection means 8. and threshold changing means lO for changing the threshold.

In the above embodiment, as shown in FIG. 2, the surface temperature T (Tpt, TFR, TRL, TRR) of each tire is
) are each tire temperature sensor 2FL, 2FR, 2RL.

The tire-to-sensor distance HD detected by the distance detecting means 8 is input from the 2RR to the abnormality determining means 4, and the tire-sensor distance HD detected by the distance detecting means 8 is input to the threshold value changing means 10. The threshold value TTH is changed as appropriate, and the abnormality determining means 4 compares the changed threshold value TTH with the surface temperature T of each tire,
When the surface temperature T is greater than the threshold value TTH, it is determined that the tire surface temperature has increased abnormally, and an alarm is issued based on this determination.

The above tire temperature sensor 2 (2FL, 2FR, 2RL,
2RR), for example, a radiant heat absorption type (infrared absorption type) temperature sensor using a platinum resistor can be suitably used.

Further, as shown in FIG. 6, which is a conceptual side view, for example, the temperature sensor 2 is placed at a predetermined distance from the tire center 14a of the tire house, facing the tread surface 14b of the tire 14 in order to detect the temperature of the tread surface 14b. Distance backward! (
(shown with a solid line) or at the center of the tire 14
It can be attached at a position directly above a (indicated by a broken line).

In addition, as described above, the temperature sensor 2 is connected to the tire tread surface 1.
4b, as shown in FIG. 7, which is a schematic plan view, a portion of the tire tread surface 14b near the inner surface 14c of the tire,
For example, it is preferable to dispose it facing a portion close to the inner surface 14c so as to detect the temperature of a portion at a distance 1 of 50 to 80 m from the inner surface 14c. When a radiant heat absorption type temperature sensor as described above is used as a tire temperature sensor, if the sensor detects a temperature increase due to radiant heat from sources other than the tire surface, the reliability of abnormality determination decreases. Therefore, in order to suppress a decrease in the reliability of abnormality determination when radiant heat is absorbed from sources other than the tire surface, it is advantageous that the temperature of the tire surface to be detected is higher. However, since tires are generally given a camber angle, the load on the inner part of the tread surface is greater, and as a result, as shown in Figure 8, the temperature of the inner part is higher than that of other parts. It's expensive. Therefore, as mentioned above, the temperature sensor 2 is designed to detect the temperature of the portion of the tire tread surface that is close to the inner surface.
By providing this, the reliability of abnormality determination can be further improved.

As the distance detecting means 8, a steering angle sensor can be used, for example, when the temperature sensor 2 is disposed at a position behind the tire shown by the solid line in FIG. That is, as shown in FIG. 7, when the tire 14 is steered about its center 14a, the distance between the tire tread surface 14b and the temperature sensor 2 changes, and the distance between the tire tread surface 14b and the temperature sensor 2 changes. Since the distance between the temperature sensor 2 and the steering angle is determined by the steering angle, the distance between the two can be detected from the steering angle by using a steering angle sensor that detects the steering angle as the distance detecting means 8.

Furthermore, if the temperature sensor 2 is placed directly above the tire as indicated by the broken line in Figure 6 above, the distance between the tire and the sensor does not change due to the steering of the tire, but only due to the vertical movement of the tire. As the distance detecting means 8, for example, a tire vertical position detection sensor that detects the vertical position of the tire with respect to the vehicle body from the movement of the suspension can be used.

Of course, if the tire-sensor distance changes depending on both the tire vertical position and the steering angle, the tire vertical position sensor and the steering angle sensor may be used in combination.

Threshold value TT) based on the distance between the tire and sensor above
is changed in the direction in which the output value of each tire temperature sensor changes due to a change in the distance, that is, as the distance becomes smaller, the threshold value T changes. What is necessary is to change it so that H becomes large.

As mentioned above, if the threshold value is changed based on the distance between the tire and the sensor, even if the output value of the tire temperature sensor includes a change due to the distance between the tire and the sensor, that change can be used to determine tire abnormality. Therefore, it is possible to perform a highly reliable abnormality determination that is not affected by changes in the distance between the tire e-sensors.

Next, an embodiment of the second invention will be described.

FIG. 3 is a block diagram showing an embodiment of the second invention. The illustrated embodiment includes tire temperature sensors 2FL, 2FR, 2RL, and 2RR similar to the embodiment shown in FIG. If the distance between the tire and the sensor detected by the distance detecting means 8 is outside a predetermined range, the abnormality determining means 4 determines that the tire is abnormal ( Prohibition means 1 that prohibits determination that the tire surface temperature has increased abnormally
0.

As mentioned above, when an abnormality is determined based on whether the tire surface temperature is higher or lower than a predetermined threshold value, the threshold value must be a predetermined value (reference value) with a certain distance between the tire and the sensor. Therefore, when the distance between the tire and the sensor becomes smaller than the standard value, the sensor output increases accordingly, resulting in a false determination that the tire is abnormal even though there is nothing abnormal about the tire. It turns out.

Therefore, the distance between the tire and the sensor that does not cause such a misjudgment, i.e., a range larger than a value smaller than the reference value by a predetermined amount, is set as the predetermined range, and if it is outside the predetermined range, By configuring the system to prohibit the determination that the tire is abnormal if the value is considerably smaller than the reference value and there is a risk of an erroneous determination as described above, it is possible to prevent the determination that the tire is abnormal due to the distance between the tire and the sensor. Misjudgment that the tire is abnormal can be prevented.

FIG. 4 is a flowchart showing an example of an abnormality determination procedure when a steering angle sensor is used as the distance detecting means 8 in the embodiment of the second invention. In this example, the tire temperature sensor 2 is disposed at the rear of the tire as shown by the solid line in FIGS. 6 and 7, near the inner surface of the tire, and is located on the right When the front tire 14 is steered to the left about its center 14a, the tread surface 14b approaches the sensor 2. Although not shown, in the case of the front left tire, when the tire is steered to the right, the tread surface approaches the sensor 2. Therefore, the predetermined range is set as a range in which the two do not come very close to each other, that is, a range in which the amount of steering is not very large.

In this example, first, the tire temperature sensor 2FL,
From 2FR, 2RL, and 2RR, the surface temperature T of each tire (
TPL, TFRI TRLI TRR) is input to the abnormality determination means 4, and the determination means 4 determines whether the surface temperature T of each tire is greater than a predetermined threshold value TTH set in advance; The current steering angle S is detected by the steering angle sensor which is the distance detecting means 8, and the steering angle S is detected by the inhibiting means 12 within a predetermined range 15.
T) Determine whether or not the value is within the range of 1 to +ST) + (+1- represents the steering direction (right, left)), and if it is outside the above predetermined range (S≦-8T)l or S≧10S When it is determined that T) l), the prohibition means 12 outputs an abnormality determination prohibition signal to the abnormality determination means 4, and the abnormality determination means 4 determines that the surface temperature T of the tire is greater than the predetermined threshold TTH. T>TT)I
) and an abnormality determination prohibition signal from the prohibition means 10 is not received (STH<S<15TH), an abnormality signal is output, and upon receiving the abnormality signal, the alarm means 6 issues an alarm.

The tire temperature sensors 2FL, 2FR, 2RL.

The type and location of the 2RR are the same as in the embodiment of the first invention.

Further, as the distance detecting means 8, various types such as a tire vertical position sensor can be used in addition to the steering angle sensor, as in the case of the first invention.

In addition, regarding the prohibition of determining that the tire is abnormal, as mentioned above, even if the tire is outside the specified range, it is considered that the tire is abnormal (T
In addition to not outputting an abnormal signal even if it is determined that the abnormality is outside the specified range, the abnormality determination means 4
The determination of whether or not there is an abnormality may be stopped, or when the T7M is outside a predetermined range, T7M may be set to a larger value than during driving, and furthermore, the abnormality determination means 4 may output an abnormality signal. However, when the value is outside a predetermined range, the operation of the alarm means 6 may be prohibited, that is, the alarm may not be issued.

Figure 5 shows the distance between the tire and sensor and the detected tire surface temperature (
As shown in the figure, as the distance between the tire and the sensor becomes smaller, the detected tire surface temperature increases.

Note that the tire abnormality determination method in the first invention is as follows:
It is not limited to the method of simply comparing the detected tire surface temperature with a predetermined threshold value as in the above embodiment, but if the method is based on the detected tire surface temperature and the threshold value, for example, Any method may be used, such as determining whether the rate of increase with respect to time is greater than a predetermined threshold value.

Further, the tire abnormality determination method in the second invention is not limited to the method of simply comparing the detected tire surface temperature with a predetermined threshold value as in the above embodiment, but also the method of determining based on the detected tire surface temperature. Any method may be used.

(Effects of the Invention) As detailed above, the first invention of the present application is configured to change the threshold value, which is the standard for tire abnormality determination, depending on the distance between the tire and the sensor. It is possible to perform highly reliable tire abnormality determination without being influenced by changes in the distance between tires.

In addition, the second invention of the present application is configured to prohibit determination that there is an abnormality when the distance between the tire and the sensor is outside a predetermined range, so if the distance between the tire and the sensor becomes too small, the output There is no risk of erroneously determining that the tire is abnormal due to an increase in the tire error, and highly reliable tire abnormality determination can be performed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the first invention of the present application, FIG. 2 is a flowchart showing an example of the abnormality determination procedure of the embodiment shown in FIG. 1, and FIG. FIG. 4 is a flowchart showing an example of the abnormality determination procedure of the embodiment shown in FIG. 3; FIG. 5 shows the relationship between the tire-sensor distance and the tire temperature sensor output. 6 and 7 are a schematic side view and a schematic plan view showing an example of the arrangement of the tire temperature sensor, and FIG. 8 is a diagram showing the temperature distribution on the tire tread surface. 2 (2FL, 2FR, 2RL, 2RR)...Tire temperature sensor 4...Abnormality determination means 8...Distance detection means 10
...Threshold value changing means 12...Prohibiting means

Claims (2)

[Claims] (1) A tire temperature sensor that detects the tire surface temperature; and an abnormality determination means that determines whether or not the tire is abnormal based on the tire surface temperature detected by the sensor and a predetermined threshold value. , comprising distance detection means for detecting the distance between the tire surface and the tire temperature sensor, and threshold value changing means for changing the threshold value based on the distance detected by the detection means. A tire abnormality determination device characterized by: (2) a tire temperature sensor that detects the surface temperature of the tire; an abnormality determination means that determines whether or not the tire is abnormal based on the tire surface temperature detected by the sensor; The tire comprises a distance detecting means for detecting the distance between the tire and the temperature sensor, and a prohibiting means for prohibiting a determination that the tire is abnormal when the distance detected by the detecting means is outside a predetermined range. Features: Tire abnormality determination device.