JP2009292443A - Tire air pressure alarm device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a receiving accuracy of a sensor detection value transmitted from a wheel side to a vehicle body side. <P>SOLUTION: A pressure sensor 36 is provided at a contact part of a bead portion 24 of a vehicle tire and a wheel 22, and detects a pressure received from the bead portion 24 in an axial direction. A determining unit compares a detection value of the pressure sensor 36 with a predetermined threshold to determine a drop of a tire pressure. An alarm informs a driver when the determining unit determines that the tire pressure drops. The determining unit determines whether the vehicle is travelling straight based on a steering angle, and determines the drop of the tire pressure when it is determined that the vehicle is travelling straight. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tire air pressure alarm device that issues an alarm when tire air pressure decreases.

  In order to drive the vehicle safely, it is necessary to keep the state of the wheels including the tires normal. Therefore, when an abnormality such as insufficient tire air pressure occurs in the wheel, it is necessary to promptly detect this and take appropriate measures. In view of this, a pneumatic alarm device is known in which an air pressure sensor and a transmitter are attached to the wheels of each wheel to detect an abnormality in tire air pressure.

For example, Patent Literature 1 discloses an alarm device in which an air pressure sensor that directly detects the pressure of a tire air chamber is attached to a wheel rim, and a detection value of this sensor is transmitted to the vehicle body side.
JP 2005-140503 A

  However, when the air pressure sensor is mounted on the wheel rim as in Patent Document 1, it may be difficult to receive the signal transmitted from the air pressure sensor on the vehicle body side due to the metal carcass disposed in the tire rubber. is there. Further, when the tire is assembled to the rim of the wheel, the bead portion of the tire may come into contact with the air pressure sensor on the rim, and the sensor may be damaged.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a tire air pressure warning technology that improves the reception accuracy of sensor detection values transmitted from the wheel side to the vehicle body side.

  One embodiment of the present invention is a tire pressure alarm device. This device is provided at a contact portion between a bead portion and a wheel of a vehicle tire, and compares a detected value of the pressure sensor and a threshold value with a pressure sensor that detects an axial pressure received from the bead portion. And determining means for determining a decrease in tire air pressure, and alarm means for notifying the driver when the determining means determines that the tire air pressure has decreased.

  According to this aspect, instead of directly detecting the tire air pressure, a decrease in the tire air pressure is determined based on the pressure detected by the pressure sensor disposed at the position sandwiched between the bead portion and the wheel. A transmitter for transmitting the sensor detection value can be arranged outside the tire instead of inside the tire.

  The determination means and the warning means may be provided on the vehicle body side, and further provided with communication means for communicating the detected value of the pressure sensitive sensor from the wheel side to the vehicle body side.

  The determination means is provided on the wheel side, and the alarm means is provided on the vehicle body side. When the determination means determines that the tire air pressure has decreased, a signal for operating the alarm means is transmitted from the wheel side to the vehicle body. You may further provide a communication means to communicate with the side.

  A steering angle sensor that detects the steering angle of the vehicle may further be provided. The determination means determines whether or not the vehicle is traveling straight on the basis of the steering angle, and determines that the tire air pressure is decreased when it is determined that the vehicle is traveling straight. During the turning of the vehicle, a lateral force is generated in the tire, and a force other than the force due to the tire air pressure acts on the pressure sensor, so that a change in the tire air pressure cannot be measured accurately. Accordingly, by determining the tire air pressure while the vehicle is traveling straight, it is possible to accurately detect a decrease in tire air pressure.

  The pressure-sensitive sensor may be mounted on a balance weight fitted into the wheel. Alternatively, the wheel-side communication means may be mounted on the balance weight.

  According to the tire pressure alarm device of the present invention, since the transmission portion of the detected tire pressure is arranged outside the tire, it is possible to improve the reception accuracy of the sensor detection value transmitted from the wheel side to the vehicle body side.

  One embodiment of the present invention is a tire air pressure alarm device that includes a wheel side unit and a vehicle body side unit, transmits tire air pressure detected by the wheel side unit to the vehicle body side unit, and determines the air pressure by the vehicle body side unit. is there.

  FIG. 1 is a schematic diagram showing the configuration and arrangement of a wheel side unit 30 in a tire pressure alarm device 10 according to an embodiment of the present invention. FIG. 1 shows a tire 20 and a wheel 22 among components constituting the wheel. The wheel 22 is connected to a vehicle body (not shown) via a suspension. Of the tire 20, a bead portion 24 that contacts the rim 23 of the wheel 22 is a portion that fixes the tire 20 to the wheel 22, and has a ring-like structure over the entire circumference of the tire 20. When air is injected into the tire air chamber 26, the bead portion 24 comes into contact with the rim 23 of the wheel 22 to make the inside of the tire 20 airtight. Since a large force is applied to the bead portion 24 due to air pressure in the tire or rotation of the wheel 22, a bead wire that is a bundle of steel wires is accommodated in the center of the bead portion 24 so as to withstand the force. ing. Around the bead wire, a heat-resistant and hard rubber called a bead filler is disposed, thereby increasing the rigidity of the bead portion 24.

  The wheel side unit 30 includes a pressure sensitive sensor 36, a transmitter 32, and a connecting portion 40 coupled to the pressure sensitive sensor and the transmitter. As shown in the figure, the connecting portion 40 is substantially U-shaped, and is arranged in a state of being sandwiched between the end portion of the rim 23 and the bead portion 24 of the tire. By receiving the pressure from the bead part 24, the connecting part 40 is fixed to the tire. The connecting portion 40 is preferably composed of a U-shaped flat plate in order to reduce a change in the shape of the contacting tire surface, but may be composed of a U-shaped bar or the like.

  The pressure sensor 36 is connected to one end of the connecting portion 40. The pressure-sensitive sensor 36 is disposed at a contact portion between the bead portion 24 of the tire and the rim 23 of the wheel 22. The pressure-sensitive sensor 36 measures the pressure P from the bead portion applied to the contact portion in the left-right direction in the drawing, that is, in the axle direction. The pressure-sensitive sensor 36 is a sensor using a pressure conductive rubber whose resistance value changes inversely proportional to the pressure applied from the outside, for example, as a switch element. Both sides of the switch element are sandwiched between a pair of electrodes, and the resistance therebetween The pressure is measured by measuring the change in value. The pressure data measured by the pressure sensor 36 is sent to the transmitter 32 via a connection (not shown). In another example, a strain gauge may be provided instead of the pressure sensitive sensor.

  In FIG. 1, the pressure-sensitive sensor 36 is drawn to have a rectangular cross section, but the actual pressure-sensitive sensor has a flat plate shape so that it can be arranged without special processing on the tire surface and the inner surface of the rim. It is preferable to form it thinly. However, a recess for accommodating the pressure-sensitive sensor 36 may be formed on the inner surface of the rim 23 so that the pressure-sensitive sensor 36 is not displaced by rotation of the tire. Also, instead of bringing the entire pressure-sensitive sensor into contact with the tire surface and the rim inner surface, the entire pressure-sensitive sensor is covered with a housing, and then a window is formed in the housing portion facing the tire surface and exposed to the window. The pressure may be detected by the sensor portion.

  The transmitter 32 receives the detected pressure value P from the pressure sensor 36 and transmits the detected value to the vehicle body side at a predetermined interval. Instead of transmitting the detection value periodically, the detection value may be transmitted only when a request signal is received from a vehicle body side unit (not shown). The transmitter 32 and the pressure sensor 36 are driven by a battery (not shown).

  The wheel side unit 30 may also serve as a balance weight fitted into the wheel. In this case, it is preferable to adjust the balance of the tire with the wheel side unit 30 attached to the tire. You may make it the structure which can attach another balance weight to the connection part 40 of the wheel side unit 30. FIG.

  In FIG. 1, the wheel side unit 30 is attached to the side facing the inside of the vehicle body. This is for facilitating communication with the vehicle body side unit installed in the vehicle body. However, you may attach the wheel side unit 30 to a wheel so that it may face the outer side of a vehicle body.

  FIG. 2 is a functional block diagram of the wheel side unit 30 and the vehicle body side unit 50 that constitute the tire air pressure alarm device 10. Each block shown here can be realized in hardware by an element such as a computer CPU and memory, an electric circuit, and a mechanical device, and in software by a computer program, etc. It is drawn as a functional block realized by the cooperation. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms by a combination of hardware and software.

As described above, the transmitter 32 of the wheel side unit 30 periodically transmits the detection value of the pressure sensor 36 via the antenna 34.
The receiver 56 of the vehicle body side unit 50 receives the detection value P of the pressure sensor transmitted from the transmitter 32 via the antenna 52, and sends the received data to an electronic control unit (hereinafter referred to as "ECU") 54. . The steering angle sensor 64 is installed inside the steering column of the vehicle, detects the steering angle by the driver, and sends it to the ECU 54. Instead of the steering angle sensor, a sensor that directly detects the direction of the steering wheel may be provided.

  The ECU 54 includes a determination unit 58 and a storage unit 60. The storage unit 60 stores in advance a lower limit value for comparison with the detection value of the pressure sensor 36. The determination unit 58 compares the received detection value P with the lower limit value. When the detected value P is less than or equal to the lower limit value, the determination unit 58 determines that the tire air pressure is decreasing. The determination unit 58 activates an alarm device 62 that is a display device such as a warning lamp, a buzzer, or a display, and notifies the driver that the tire air pressure has decreased.

  The above lower limit value can be set from several viewpoints. For example, it may be defined as the pressure when the vehicle performance or fuel consumption decreases by a certain rate due to a decrease in tire air pressure. This lower limit is determined based on the pressure detected by the pressure sensor when the tire pressure is reduced using an actual vehicle.

  1 and 2, only one wheel on which the wheel side unit 30 is installed is described, but the wheel side unit 30 is preferably installed on all the wheels of the vehicle. In this case, it is preferable to include the wheel identification information in the communication from the wheel side unit 30 to the vehicle body side unit 50 so that the determination unit 58 can specify which wheel tire pressure is decreasing.

Next, the principle of tire pressure detection in the tire pressure alarm device of this embodiment will be described.
FIG. 3 is an enlarged view of the wheel side unit shown in FIG. 1 and tire components around it. Assuming that the vehicle is traveling straight, the force applied near the bead portion of the tire can be divided into the following two. 1. The resultant force of the fitting force and wheel load generated by the bead portion in the upward direction in the figure (indicated by arrow A in FIG. 3). 2. A force (indicated by an arrow B in FIG. 3) that presses the tire against the wheel rim by the air pressure in the tire air chamber applied in the right side (outer side of the wheel) direction in the drawing. Therefore, by detecting the force indicated by the arrow B with the pressure-sensitive sensor 36 disposed between the bead portion and the rim, it is possible to measure a change in tire air pressure.

  Note that during the turning of the vehicle, a lateral force is generated in the tire and a force other than the force due to the tire air pressure acts in the wheel outer direction. Therefore, the change in the tire air pressure cannot be accurately measured only by the pressure sensor 36. Therefore, in the present embodiment, the tire air pressure is determined only while the vehicle is traveling straight.

  As described above, by disposing the pressure-sensitive sensor 36 between the tire bead portion and the wheel rim, the transmitter 32 is disposed outside the tire via the connecting portion 40 as shown in FIG. Is possible. This is more advantageous than the conventional configuration in which the tire pressure sensor and the transmitter are arranged in the tire air chamber. Because the carcass (not shown) in the tire contains metal, transmission from the inside of the tire is hindered by the carcass and the reception accuracy is lowered. This is because such a problem can be avoided by arranging.

  FIG. 4 is a flowchart of tire pressure determination in the present embodiment. First, the determination unit 58 determines whether or not the vehicle is traveling straight forward at a predetermined timing (for example, immediately after engine startup or periodically) based on the detected value of the steering angle sensor 64 (S10). As described above, the air pressure cannot be accurately measured by the pressure sensor 36 when the vehicle is turning. Therefore, when the vehicle is not traveling straight (N in S10), this flow is terminated. When the vehicle is traveling straight (Y in S10), the determination unit 58 receives the detection value of the pressure sensor 36 from the receiver 56 (S12). If the receiver 56 may receive a detection value periodically received, or if the wheel side unit 30 and the vehicle body side unit 50 are configured to be capable of bidirectional communication, the determination unit 58 may You may request | require that the detection value of the pressure sensor 36 is sent with respect to the wheel side unit 30. FIG. The determination unit 58 compares the received detection value with a predetermined lower limit value (S14). When the detected value exceeds the lower limit value (N in S14), this flow ends. When the detected value is equal to or lower than the lower limit value (Y in S14), the determination unit 58 operates the alarm device 62 to notify the driver of a decrease in tire air pressure (S16).

  As described above, according to the present embodiment, instead of directly detecting the tire air pressure, a pressure sensor is provided at a position sandwiched between the tire bead portion and the wheel rim, and the pressure detected by the pressure sensor is adjusted. Based on this, the suitability of the tire pressure was determined. This makes it possible to arrange a transmitter for transmitting the detected value outside the tire instead of inside the tire.

  Thus, by arranging the transmitter outside the tire, communication with the unit on the vehicle body side is not hindered by the carcass or the like inside the tire, and communication accuracy is improved. Further, when replacing the battery incorporated in the wheel side unit, the wheel side unit can be removed without removing the tire from the rim, so that maintenance such as replacement of the battery incorporated in the wheel side unit is facilitated. In addition, since the wheel-side unit may be attached after the tire is assembled to the wheel, the work process can be shortened and facilitated by a configuration in which an air pressure sensor or the like is arranged on the wheel rim before the tire is assembled as in the conventional case. .

  The present invention has been described based on some embodiments. It should be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to combinations of the respective components and processing processes, and such modifications are within the scope of the present invention. is there.

  The threshold value for air pressure determination in the determination unit is not limited to one, but two or more threshold values may be set, and the degree of alarm may be changed every time each threshold value is exceeded. .

  In the embodiment, it has been described that the tire pressure is determined by the vehicle body side unit based on the detection value of the pressure sensor detected by the wheel side unit. The air pressure may be determined. In this case, if it is determined that the tire air pressure has decreased, a signal for operating the alarm on the vehicle body side may be transmitted from the transmitter of the wheel side unit.

It is a block diagram of the wheel side unit of the tire air pressure alarm device by one Embodiment of this invention. It is a functional block diagram of a wheel side unit and a vehicle body side unit of a tire air pressure alarm device. It is a figure explaining the principle which detects tire pressure. It is a flowchart of a tire pressure warning.

Explanation of symbols

  10 tire pressure alarm device, 20 tire, 22 wheel, 23 rim, 24 bead part, 26 tire air chamber, 30 wheel side unit, 32 transmitter, 34 antenna, 36 pressure sensor, 50 vehicle body side unit, 52 antenna, 54 ECU, 56 receiver, 58 determination unit, 60 storage unit, 62 alarm device.

Claims (6)

A pressure-sensitive sensor that is provided at a contact portion between a bead portion of a vehicle tire and a wheel and detects an axial pressure received from the bead portion;
A determination means for comparing the detected value of the pressure sensor and a threshold value to determine a decrease in tire air pressure;
Alarm means for informing the driver when it is determined by the determining means that the tire air pressure has decreased;
A tire pressure alarm device comprising: The determination means and the warning means are provided on the vehicle body side,
The tire pressure alarm device according to claim 1, further comprising communication means for communicating a detection value of the pressure sensitive sensor from a wheel side to a vehicle body side. The determination means is provided on the wheel side, and the warning means is provided on the vehicle body side,
2. The tire pressure alarm according to claim 1, further comprising a communication unit configured to communicate a signal for operating the alarm unit from a wheel side to a vehicle body side when the determination unit determines that the tire air pressure has decreased. apparatus. A steering angle sensor for detecting the steering angle of the wheel;
4. The tire according to claim 2, wherein the determination unit determines whether or not the vehicle is traveling straight on the basis of the steering angle, and performs a determination to decrease the tire air pressure when it is determined that the vehicle is traveling straight. Pneumatic alarm device.   The tire pressure alarm device according to any one of claims 1 to 4, wherein the pressure sensor is mounted on a balance weight fitted into a wheel.   6. The tire pressure alarm device according to claim 5, wherein a communication means on a wheel side is mounted on the balance weight.

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