JP2006306344A - Tire air pressure monitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire air pressure monitor capable of determining vehicle running and stopping without need for additional installation of a rotation sensor for detecting tire rotation or the like in a transmitter. <P>SOLUTION: Vehicle running or stopping is determined from an in-tire temperature detected by a temperature sensor 10b which each of the transmitters A, B, C, D provided in tires 1, 2, 3, 4 has. The transmitter transmits electric waves at constant intervals during vehicle running and stops transmission of electric waves during vehicle stopping or transmits electric waves at constant intervals longer than those during vehicle running. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention belongs to a technical field of a tire pressure monitoring device that transmits each tire pressure to a receiving device provided on the vehicle body side by a pneumatic sensor provided on each tire.

This type of technology includes a pressure sensor that detects tire air pressure in a transmitter provided in each tire, a temperature sensor that detects the temperature in the tire, and a rotation sensor that detects rotation of the tire (such as a centrifugal force switch or an acceleration sensor). Etc.), and when it is determined that the vehicle has started running by detecting the rotation of the tire, the tire pressure is intermittently transmitted and the tire temperature information is transmitted, and when it is determined that the vehicle has stopped, the transmission is stopped. Is disclosed (for example, see Patent Document 1).
JP 2001-246914 A

  However, in the above prior art, a rotation sensor that detects the rotation of the tire is provided to determine whether the vehicle is running or stopped. However, the provision of the rotation sensor increases the number of components of the transmitter and increases costs. There was a problem of becoming.

  The present invention has been made paying attention to the above problems, and its object is to provide a tire pressure monitor that can determine whether the vehicle is running or stopped without providing a rotation sensor or the like for detecting tire rotation in the transmitter. Is to provide a device.

  In order to achieve the above object, in the present invention, a tire air pressure detecting unit that is attached to each of a plurality of tires equipped in a vehicle and detects each tire air pressure, and a tire internal temperature detecting unit that detects each tire internal temperature, In a tire pressure monitoring device comprising: a transmitting means for transmitting the detected tire pressure by a radio signal; and a receiving means attached to the vehicle side for receiving a radio signal, whether the vehicle is running or stopped is determined from the temperature in the tire. The transmission means transmits tire pressure detected at a set interval when the vehicle is running, stops transmission of the detected tire air pressure when the vehicle is stopped, or detects tire pressure detected at an interval longer than the set interval. I sent it.

  In the tire air pressure monitoring device of the present invention, since the vehicle running and stopping are determined from the temperature in the tire, it is possible to determine the vehicle running and stopping without using a rotation sensor or the like. Since the number of parts can be reduced and the transmitter can be made smaller, the attachment of the transmitter can be improved.

  Hereinafter, the best mode for realizing the tire pressure monitoring device of the present invention will be described based on the first embodiment.

  First, the configuration will be described.

  FIG. 1 is a system diagram showing a vehicle to which the tire air pressure monitoring device of the first embodiment is applied. The vehicle is provided inside each of tires 1, 2, 3, and 4, and includes tire air pressure information, tire temperature information, and the like. Transmitters (transmitting means) A, B, C, D for transmitting, receivers (receiving means) E, F, G, H for receiving transmission signals from the transmitters A, B, C, D, receivers A tire pressure controller or the like that processes tire pressure information and the like based on signals received by E, F, G, and H is provided.

  Transmitters A, B, C, and D are attached to the road wheels of the front and rear tires 1, 2, 3, and 4, respectively, and detect the tire pressure and the tire internal temperature of each tire. The temperature information in the tire is transmitted to the receivers E, F, G, and H by radio signals.

  The receivers E, F, G, and H receive each information transmitted from the transmitters A, B, C, and D and input the information to the tire pressure alarm controller 5.

  The tire pressure alarm controller 5 displays tire pressure information and temperature information inside the tires 1, 2, 3, and 4 on the front and rear wheels on the display 6, and tires 1, 2, 3, and 4 on the front and rear wheels. When it is determined that at least one tire pressure of the air pressure has decreased or an abnormal increase in the temperature in the tire has occurred, a lamp lighting command is output to the warning lamp 7.

  FIG. 2 is a detailed view showing the tire pressure monitoring device of the first embodiment.

  The transmitters A, B, C, and D include a pressure sensor (tire pressure detecting means) 10a for detecting tire pressure, a temperature sensor (tire temperature detecting means) 10b for detecting tire temperature, and an integrated circuit for specific applications. ASIC 10c, a transmitter 10d, and a transmitting antenna 10e. In order to ensure the battery life, radio waves are transmitted at a fixed interval while the vehicle is traveling, and radio waves are stopped when the vehicle is stopped. The interval between the radio wave transmissions is set to a time that can sufficiently detect a change in tire air pressure.

  In order to monitor the tire air pressure even when the vehicle is stopped, the transmitters A, B, C, and D may transmit radio waves at intervals longer than the transmission interval while the vehicle is running even when the vehicle is stopped. .

  Each of the receivers E, F, G, and H includes a reception antenna 11a that receives transmission data from the transmitters A, B, C, and D, and a tuner 11b that is a reception circuit.

  The tire pressure alarm controller 5 receives 5V power supply circuit 5a, a microcomputer 5b that receives received data from each tuner 11b and performs various information processing, and each tire 1, 2, 3, 4 based on the received data. A display drive circuit 5c that outputs a display drive command for displaying tire pressure information and a temperature rise in the tire to the display 6, and a tire pressure warning command when a pressure drop occurs by judging pressure information and temperature information of the mounted tire from the received data. And a warning lamp output circuit 5d for outputting to the warning lamp 7 when the abnormal temperature rises.

  Next, the operation will be described.

[Vehicle travel judgment process by temperature sensor]
In the present embodiment, as described above, the transmitters A, B, C, and D transmit radio waves at regular intervals to determine that the vehicle is traveling to ensure battery life, and the vehicle stops. If it is determined that the transmission is being performed, the transmission of the radio wave is stopped, or the radio wave is transmitted at an interval longer than the transmission interval during traveling of the vehicle.

  Hereinafter, when it is determined that the vehicle is stopped, the transmitters A, B, C, and D will stop transmitting, but there may be cases where radio waves are transmitted at intervals longer than the transmission interval while the vehicle is traveling. A similar process may be performed for determining whether the vehicle is stopped and running.

  In order to determine whether the vehicle is stopped or running, it is necessary to detect the rotation of the tire. In order to detect the rotation of the tire, it is conceivable to newly provide a sensor such as a rotation sensor, a centrifugal force sensor, an acceleration sensor, or the like in the transmitters A, B, C, and D. However, by providing a new sensor, the number of components of the transmitters A, B, C, and D increases, and the cost increases and the transmitters A, B, C, and D are formed larger, so Sexual deterioration occurs. In addition, sensors such as a rotation sensor, a centrifugal force sensor, an acceleration sensor, and the like have attachment directivity, and if they are attached in the wrong direction, erroneous detection is performed, so that the work at the time of attachment becomes complicated.

  Therefore, in this embodiment, the temperature sensor that detects the temperature inside the tire is also used as a means for detecting the tire rotation.

  FIG. 3 is a diagram showing a change in tire temperature from the start to the stop of the vehicle.

  When the vehicle starts, the temperature in the tire rises rapidly due to frictional heat between the tires 1, 2, 3, 4 and the road surface and heat radiation from the brake. The amount of increase varies depending on the load on the tires 1, 2, 3, and 4 and the running state, but increases from about 15 ° C to about 25 ° C. After the temperature in the tire rises to some extent, the tire temperature changes up and down due to acceleration or deceleration of the vehicle, but does not change significantly. When the vehicle stops, the temperature in the tire becomes a natural heat dissipation state and falls.

  In this embodiment, when the tire temperature change ΔT during the first set time Δt1 detects an increase greater than the set temperature, it is determined that the vehicle has started, and the tire temperature change ΔT ′ during the second set time Δt2 The vehicle was judged to have stopped when it detected a drop below the set temperature. Further, a threshold value Tt is provided so that a fall in the tire temperature during traveling is not erroneously determined as a vehicle stop, the tire temperature is equal to or less than the threshold value Tt, and the tire temperature change ΔT ′ during the second set time Δt2. When the vehicle detects a drop below the set temperature, it is determined that the vehicle has stopped. For example, the threshold value Tt may be set using any one of the following three calculation methods, or two or more may be combined. For example, a value obtained by adding a certain temperature to the temperature Ts when it is determined that the vehicle has started is set as the threshold value Tt. Further, an average temperature Ta after determining that the vehicle has started is calculated, and a value obtained by subtracting a constant temperature from the average temperature Ta is set as the threshold value Tt. Further, an average temperature Ta after determining that the vehicle has started is calculated, and an intermediate value from the temperature Ts when it is determined that the vehicle has started is set as the threshold value Tt.

  In FIG. 3, the transmitters A, B, C, and D stop radio wave transmission until the time ts when the temperature change ΔT in the tire during the first set time Δt1 detects an increase greater than the set temperature, and after the time ts. Transmitters A, B, C, D transmit radio waves at regular intervals. The transmitters A, B, C, and D stop the radio wave transmission after the time ts when the change in tire temperature ΔT ′ during the second set time Δt2 detects an increase greater than the set temperature.

  FIG. 4 is a flowchart showing a flow of processing for setting radio wave transmission according to the temperature in the tire, which is performed in the transmitters A, B, C, and D.

  In step S1, the temperature in the tire is measured by the temperature sensor 10b, and the temperature in the tire is stored.

  In step S2, the temperature in the tire is measured by the temperature sensor 10b after the first set time Δt1 after the execution of step S1.

  In step S3, a tire temperature change ΔT is calculated from the tire temperature measured in steps S1 and S2.

  In step S4, it is determined whether or not the tire temperature change ΔT is greater than the set temperature. When the tire internal temperature change ΔT is larger than the set temperature, the process proceeds to step S5, and when the tire internal temperature change ΔT is equal to or lower than the set temperature, the process returns to step S1.

  In step S5, the transmitters A, B, C, and D start tire pressure information and tire temperature information at regular intervals.

  In step S6, the temperature in the tire is measured by the temperature sensor 10b, and the temperature in the tire is stored.

  In step S7, the temperature in the tire is measured by the temperature sensor 10b after the second set time Δt2 after the execution of step S6.

  In step S8, a tire temperature change ΔT ′ is calculated from the tire temperature measured in steps S6 and S7.

  In step S9, it is determined whether or not the tire internal temperature is lower than the threshold value. When the tire internal temperature is lower than the threshold value, the process proceeds to step S10. When the tire internal temperature is higher than the threshold value, the process returns to step S5.

  In step S10, it is determined whether or not the tire temperature change ΔT ′ is greater than the set temperature. When the tire internal temperature change ΔT ′ is larger than the set temperature, the process proceeds to step S11, and when the tire internal temperature change ΔT is equal to or lower than the set temperature, the process returns to step S5.

  In step S11, the transmitters A, B, C, and D stop starting tire pressure information and tire temperature information.

  With this action, the transmitter A, B, C, D can be determined to run and stop the vehicle without providing a device used only for detecting the rotation of the tire, such as a rotation sensor. The transmission method of B, C, and D can be controlled.

  Next, the effect will be described.

  (1) Using the temperature sensor 10b that detects the temperature inside the tire, it is determined whether the vehicle is running or stopped, and the transmitters A, B, C, and D transmit radio waves at regular set intervals while the vehicle is running. The transmission of radio waves was stopped while the vehicle was stopped. Therefore, since there is no need to provide a rotation sensor or the like for detecting the rotation of the tire in the transmitters A, B, C, and D, the cost can be reduced, and the transmitters A, B, C, and D can be formed small, and the mounting property Can be improved.

  (2) Using the temperature sensor 10b that detects the temperature inside the tire, it is determined whether the vehicle is running or stopped, and the transmitters A, B, C, and D transmit radio waves at regular set intervals while the vehicle is running. When the vehicle is stopped, the radio wave is transmitted at an interval longer than the transmission interval while the vehicle is running. Therefore, the tire pressure can be monitored even when the vehicle is stopped, and the tire pressure can be monitored more accurately.

  (2) When the tire internal temperature change ΔT during the first set time Δt1 detects an increase greater than the set temperature, it is determined that the vehicle has started. Therefore, the start of the vehicle can be detected by the temperature sensor 10b that detects the temperature in the tire without using a rotation sensor that detects the rotation of the tire.

  (3) When the temperature change ΔT ′ in the tire during the second set time Δt2 detects a decrease lower than the set temperature, it is determined that the vehicle has stopped. Therefore, the stop of the vehicle can be detected by the temperature sensor 10b that detects the temperature in the tire without using a rotation sensor that detects the rotation of the tire.

  (4) When the temperature inside the tire is equal to or lower than the threshold Tt and the temperature change ΔT ′ within the tire during the second set time Δt2 is detected to be lower than the set temperature, it is determined that the vehicle has stopped. Therefore, it is possible to prevent erroneous detection that the vehicle is stopped due to a decrease in the temperature in the tire during traveling.

  Although the oil pump of the present invention has been described based on the first embodiment, the specific configuration is not limited to this embodiment, and departs from the gist of the invention according to each claim of the claims. Unless otherwise, design changes and additions are permissible.

  For example, in the present embodiment, three calculation methods for setting the threshold value Tt are listed, but in addition, a value obtained by adding a constant temperature from the tire internal temperature at the time of stopping may be used as the threshold value Tt.

  In the embodiment, the tire pressure monitoring device in a vehicle equipped with four tires such as a passenger car is shown, but the tire pressure monitoring device in a small vehicle equipped with three tires or a large vehicle equipped with five or more tires may be used. Can be applied.

It is a whole system figure of the amount of vehicles equipped with a tire pressure monitor device. It is detail drawing which shows a tire pressure monitoring apparatus. It is the figure which showed the temperature change of the tire from a vehicle travel start to a stop. It is a flowchart which shows the flow of the process which sets transmission of the electromagnetic wave by the temperature in a tire performed within a transmitter.

Explanation of symbols

10a Pressure sensor 10b Temperature sensor A, B, C, D Transmitter E, F, G, H Receiver

Claims (4)

Tire pressure detecting means attached to each of a plurality of tires mounted on the vehicle and detecting each tire air pressure;
Tire temperature detection means for detecting the temperature in each tire;
A transmission means for transmitting the detected tire pressure with a radio signal;
A receiving means attached to the vehicle side for receiving the radio signal;
In a tire pressure monitoring device comprising:
A travel determination means for determining vehicle travel and stop from the temperature in the tire,
The transmission means transmits the detected tire air pressure at a set interval when the vehicle is running, stops transmission of the detected tire air pressure when the vehicle is stopped, or detects the detected tire air pressure at an interval longer than the set interval. A tire pressure monitoring device for transmitting. In the tire pressure monitoring device according to claim 1,
The tire pressure monitoring device according to claim 1, wherein the traveling determination means determines that the vehicle has started traveling when a temperature change per first set time of the tire internal temperature rises by a predetermined temperature or more. In the tire pressure monitoring device according to claim 1 or 2,
The tire pressure monitoring device according to claim 1, wherein the travel determination means determines that the vehicle has stopped when a temperature change per second set time of the tire internal temperature falls below a set temperature. The tire pressure monitoring device according to any one of claims 1 to 3,
The travel determination means determines that the vehicle has stopped when the temperature inside the tire is lower than a threshold value and the temperature change per second set time of the tire temperature falls below a set temperature. A tire pressure monitoring device.

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