JP2003094918A - Vehicle with tire pneumatic pressure lowering detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire pneumatic pressure lowering detector capable of increasing the accuracy of determination on pressure reduction during high speed running. SOLUTION: In this vehicle, the tire pneumatic pressure lowering detector is installed to detect the lowering of the internal pressure of a tire based on the information on the rotation of the tire obtained from the tire installed on the vehicle. A breaker and a band for reinforcing the breaker are disposed between the tread part and the carcass of the tire, the breaker angle of the breaker is 24 to 26 deg., and the tire having a flat rate set to 30 to 60% is installed.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle provided with a tire pressure drop detecting device. More specifically, the present invention relates to a vehicle provided with a tire pressure drop detection device that can improve the accuracy of pressure reduction determination at high speeds by specifying tire specifications. 2. Description of the Related Art Conventionally, a tire pressure drop detecting device (DWS) for detecting pressure reduction of a tire based on rotation (wheel speed) information of a four-wheel tire mounted on a vehicle has been known. is there. This device uses the principle that when the tire is depressurized, the outer diameter (the dynamic load radius of the tire) is smaller than that of a tire having a normal internal pressure, so that the rotational speed and the rotational angular speed are increased as compared with other normal tires. For example, in a method of detecting a decrease in internal pressure from a relative difference in the rotational angular velocity of a tire (see JP-A-63-30501),
As the determination value DEL, DEL = {(F1 + F4) / 2− (F2 + F3) / 2}.
/ {(F1 + F2 + F3 + F4) / 4} × 100 (%). Here, F1 to F4 are the rotational angular velocities of the front left tire, front right tire, rear left tire and rear right tire, respectively. However, when the tires are flat tires, a tread lift occurs due to centrifugal force at a high speed, and there is a case where a difference in radius between the tires cannot be obtained. In that case, there is a problem that the DWS does not detect the reduced pressure even when the tire is reduced in pressure. [0004] In view of the circumstances described above, an object of the present invention is to provide a vehicle provided with a tire pressure drop detecting device capable of improving the accuracy of pressure reduction determination at high speed. [0005] A vehicle provided with a tire pressure drop detecting device of the present invention is provided with a tire pressure drop detecting device for detecting a tire pressure drop based on rotation information obtained from the tire. A vehicle, wherein a breaker and a band for reinforcing the breaker are arranged between a tread portion of the tire and a carcass, and the breaker angle of the breaker is 24 to 26 ° and the flattening rate is 30 to It is characterized by being equipped with a tire set to 60%. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle equipped with a tire pressure drop detecting device according to the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, the tire pressure drop detecting device includes four tires FL, FR, RL, and RR (hereinafter collectively referred to as Wi, where i = 1-4, 1: front left tire, 2: front right tire, 3: rear left tire, 4: rear right tire) to detect whether or not the air pressure is reduced. And a normal rotation information detecting means 1 provided in such a manner. The rotation information detecting means 1 uses a rotation such as a wheel speed sensor or a dynamo that generates a rotation pulse using an electromagnetic pickup or the like and measures a wheel speed (rotation speed) from the number of pulses. Generate electricity,
An angular velocity sensor or the like including one that measures the wheel speed from this voltage can be used. The rotation information detecting means 1
Is supplied to a control unit 2 which is a computer such as an ABS. Connected to the control unit 2 are a liquid crystal display element for notifying the tire Wi whose air pressure has decreased, a display unit 3 composed of a plasma display element or a CRT, and an initialization switch 4 that can be operated by a driver. I have. As shown in FIG. 2, the control unit 2 has an I / O interface 2a required for transmitting and receiving signals to and from an external device, and a C functioning as a center of arithmetic processing.
A PU 2b, a ROM 2c in which a control operation program of the CPU 2b is stored, and a RAM 2d from which data and the like are temporarily written when the CPU 2b performs a control operation, and from which the written data and the like are read. I have. The rotation information detecting means 1 outputs a pulse signal (hereinafter referred to as a wheel speed pulse) corresponding to the number of rotations of the tire. Based on the output wheel speed pulse,
A predetermined sampling period ΔT (sec), for example, ΔT = 1
After calculating the rotational angular velocity of each tire every second, the wheel velocity is calculated from the rotational angular velocity. In the present embodiment, the tire pressure drop detecting device includes a rotation information detecting means 1 for detecting the rotation information of each tire, a storage means for storing the rotation information of each tire, And determination means for determining The decompression judgment value (DEL) for detecting a decrease in the air pressure of the tire Wi is, for example, a comparison of a difference between two diagonal sums of a front wheel tire and a rear wheel tire. The sum of the signals from one pair of wheels is subtracted from the sum of the signals from the other pair of wheels on a diagonal line, and the ratio of the result to the average value of the two sums is given by the following equation (1). Desired. DEL = {(V1 + V4) / 2− (V2 + V3) / 2} / {(V1 + V2 + V3 + V4) / 4} × 100 (%) (1) Here, as a general tendency, The correlation (linkage) between the dynamic load radius (the distance traveled by one rotation of the tire by 2π divided by 2π) and the rolling resistance is strong, and the rolling resistance of a low flat tire (for example, run flat) increases rapidly even at high speed. And there is little dependency change due to a decrease in internal pressure. On the other hand, it is known that a high flat tire (for example, a studless tire) has a sudden change in speed dependency at 80 km / h or more at a low internal pressure. Therefore, in the case of the run flat, the dynamic load radius difference appears in any speed range, so that the DW
S determination is possible. Therefore, it is conceivable that the tires should be specified so that the detection sensitivity is not reduced by DWS at high speed and the determination can be made at any speed. The tire pressure drop detecting device according to the present embodiment can easily detect a difference in tire radius at the time of pressure reduction by changing the specification of the tire mounted on the vehicle, and can detect the pressure reduction even at high speed. DWS can be obtained. For example, a difference in radius of the tire at the time of decompression is more likely to occur due to a round tread radius and high lateral rigidity.
In addition, in order to maintain the difference in radius of the tire at high speed, it is necessary that the tire be reinforced with high lateral rigidity and a band. Therefore, as a specification of the tire, the breaker angle (the angle in the direction in which the tread radius is rounded) is set to 24 to 26 ° in order to make the tread radius round and thereby to easily make a difference in the radius of the tire. . It should be noted that the maximum value of the breaker angle is 26% from the current production and from the examples described later, and the minimum value is preferably set to 24% so as to prevent the lateral rigidity from being too high. Reinforce with a band to prevent tread lift due to centrifugal force. The flattening rate is set to 30 to 60% in order to prevent a tread lift at a high speed and make the tire radius difference easily. For example, a reinforced tire such as a run flat having high lateral rigidity is used. Note that the maximum value of the flattening rate is 60% from the example described later, and the minimum value is
It is preferable that the flattening rate is the smallest, that is, 30%. In FIG. 3, a pneumatic radial tire for a passenger car is a tire having a tire size of 225 / 50ZR16, and has a tread portion 11 and a tread portion 11.
A sidewall portion 12 extending radially inward from the tire, a bead portion 13 located at a radially inner end of the sidewall portion 12, and a bead core 14 of the bead portion 13 passing through the sidewall portion 12 in the tire axial direction. Carcass 15 that turns from inside to outside, and tread 1
1 and a breaker 16 arranged radially outside the carcass 15 and a band 17 arranged radially outside the breaker 16. Further, a bead apex 18 having a triangular cross section rises outside the bead core 14 in the tire radial direction. The radial tire has a ratio of a tire section height H to a tire maximum width W (H / W) × 100.
(%) Is a flat tire of 30 to 60%, and a block pattern having blocks divided by a plurality of vertical grooves and horizontal grooves is formed on the surface of the tread portion 11. The carcass 15 has at least one carcass cord having a radial or semi-radial carcass cord inclined at an angle of 70 to 90 degrees with respect to the tire equator C.
In the present embodiment, it is composed of one carcass ply 6A,
As the carcass cord, an organic fiber cord such as polyester is used. The breaker 16 is disposed adjacent to the carcass 6, and is composed of, for example, two cut plies, and the cut ply is a belt cord made of an organic fiber cord such as aromatic polyamide or nylon. C is arranged side by side at a breaker angle of 24 to 26 ° with respect to C, and the belt cords of each cut ply are arranged in a direction crossing each other. The breaker 16 has two outer edges 16a.
The belt width, which is the distance in the tire axial direction between the tire and the tire 16b, is the width in the tire axial direction of the ground contact surface in the normal state of the tire when the tire is mounted on the standard rim 19 and the normal internal pressure and the normal load are applied. Is formed substantially equal to the contact width. The band 17 is formed by forming one or more, for example, two parallel band cords made of an organic or inorganic material by rubber coating on a long strip-like ply starting from one outer edge 16 a of the breaker 16. As the other outer edge 1
6b, it is formed by spirally winding substantially parallel to the tire equator C. The band cord is made of an organic fiber cord such as steel cord or aromatic polyamide and has a modulus of 5.88 × 10 ⁶ P
a or more. Next, the present invention will be described based on examples, but the present invention is not limited to only these examples. Example As a tire having a low rigidity and easily causing a tread lift, a vehicle equipped with a highly flat studless (SJ5, tire size: 245 / 70R16) and a runkle were prepared. The vehicle is equipped with a DWS. The vehicle load at this time was 4 kN. Next, the tire was driven on an Okayama test course of Sumitomo Rubber Industries, Ltd. under three conditions of air pressures of 120 kPa, 140 kPa, and 200 kPa to examine the relationship between speed and dynamic load radius (Comparative Example 1). The result is shown in FIG. From FIG. 4, the speed dependence of the dynamic load radius starts to be affected at around 100 km / h.
It can be seen that at 20 km / h, a reversal phenomenon occurs, which has a large effect on DWS detection. Next, in order to increase lateral rigidity, a vehicle equipped with a run flat (SP10, tire size: 195 / 60R15) as a low-flat tire having a flatness of 65% and a breaker angle of 17 °. Corolla was prepared. The run flat is not reinforced by a band. The vehicle load at this time is 4.4
kN. Next, similarly to Comparative Example 1, the relationship between the speed and the dynamic load radius was examined (Comparative Example 2). The result is shown in FIG.
Shown in From FIG. 5, it is improved from Comparative Example 1, but 150 k
It can be seen that the reversal phenomenon also occurs near m / h. Next, the breaker angle of the tire of Comparative Example 2 was set to 26 °, and a full nylon band was added to the breaker so as to suppress the centrifugal force. Then, Comparative Example 1
Similarly, the relationship between the speed and the dynamic load radius was examined (Example 1). FIG. 6 shows the result. From FIG. 6, it was confirmed that the radius difference of the decompressed tire was firmly maintained, and that the tire did not reverse even at a high speed of 160 km / h. Table 1 shows the determination times at 25% pressure reduction in Comparative Examples 1 and 2 and Example 1 so far. From Table 1, it can be seen that the DWS mounted on the vehicle equipped with the tire of Example 1 determines the pressure reduction in a shorter time than the cases of Comparative Examples 1 and 2. [Table 1] As described above, according to the present invention,
The accuracy of the decompression determination at high speed can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a tire pressure drop warning device according to the present invention. FIG. 2 is a block diagram showing an electrical configuration of the tire pressure drop warning device in FIG. 1; FIG. 3 is a longitudinal sectional view of a tire. FIG. 4 is a diagram illustrating the relationship between speed and dynamic load radius for studless; FIG. 5: Flatness is 60%, breaker angle is 17
FIG. 9 is a diagram illustrating a relationship between a speed and a dynamic load radius for a run flat of °. FIG. 6 is a diagram showing the relationship between speed and dynamic load radius for a run flat to which a breaker angle is set to 26 ° and a nylon full band is added. [Description of Signs] 1 Rotation information detecting means 2 Control unit 3 Display 4 Initialization switch 11 Tread section 12 Side wall section 13 Bead section 14 Bead core 15 Carcass 16 Breaker 17 Band 19 Rim

Claims (1)

Claims 1. A vehicle provided with a tire pressure decrease detecting device for detecting a decrease in tire internal pressure based on rotation information obtained from a tire, wherein a vehicle is provided between a tread portion of the tire and a carcass. A breaker and a band for reinforcing the breaker are arranged, and the breaker has a breaker angle of 24 to 26 ° and a tire having a flatness of 30 to 60%. Vehicle equipped with tire pressure drop detection device.