JP2012171463A - Tire air pressure detector - Google Patents

Tire air pressure detector Download PDF

Info

Publication number
JP2012171463A
JP2012171463A JP2011034730A JP2011034730A JP2012171463A JP 2012171463 A JP2012171463 A JP 2012171463A JP 2011034730 A JP2011034730 A JP 2011034730A JP 2011034730 A JP2011034730 A JP 2011034730A JP 2012171463 A JP2012171463 A JP 2012171463A
Authority
JP
Japan
Prior art keywords
air pressure
tire
alarm
pressure
tire air
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2011034730A
Other languages
Japanese (ja)
Inventor
Koji Murayama
Nobuya Watabe
Yoshinori Hanai
孝二 村山
宣哉 渡部
淑典 花井
Original Assignee
Denso Corp
株式会社デンソー
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Denso Corp, 株式会社デンソー filed Critical Denso Corp
Priority to JP2011034730A priority Critical patent/JP2012171463A/en
Publication of JP2012171463A publication Critical patent/JP2012171463A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60CVEHICLE TYRES; TYRE INFLATION; TYRE CHANGING OR REPAIRING; REPAIRING, OR CONNECTING VALVES TO, INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C23/00Devices for measuring, signalling, controlling, or distributing tyre pressure or temperature, specially adapted for mounting on vehicles; Arrangement of tyre inflating devices on vehicles, e.g. of pumps, of tanks; Tyre cooling arrangements
    • B60C23/02Signalling devices actuated by tyre pressure
    • B60C23/04Signalling devices actuated by tyre pressure mounted on the wheel or tyre
    • B60C23/0408Signalling devices actuated by tyre pressure mounted on the wheel or tyre transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
    • B60C23/0422Signalling devices actuated by tyre pressure mounted on the wheel or tyre transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver characterised by the type of signal transmission means
    • B60C23/0433Radio signals
    • B60C23/0447Wheel or tyre mounted circuits
    • B60C23/0455Transmission control of wireless signals
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60CVEHICLE TYRES; TYRE INFLATION; TYRE CHANGING OR REPAIRING; REPAIRING, OR CONNECTING VALVES TO, INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C23/00Devices for measuring, signalling, controlling, or distributing tyre pressure or temperature, specially adapted for mounting on vehicles; Arrangement of tyre inflating devices on vehicles, e.g. of pumps, of tanks; Tyre cooling arrangements
    • B60C23/02Signalling devices actuated by tyre pressure
    • B60C23/04Signalling devices actuated by tyre pressure mounted on the wheel or tyre
    • B60C23/0408Signalling devices actuated by tyre pressure mounted on the wheel or tyre transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
    • B60C23/0474Measurement control, e.g. setting measurement rate or calibrating of sensors; Further processing of measured values, e.g. filtering, compensating or slope monitoring
    • B60C23/0477Evaluating waveform of pressure readings

Abstract

PROBLEM TO BE SOLVED: To surely give an alarm about a decrease in tire air pressure on the basis of an alarm threshold following a change in the air pressure in a tire, which is caused by traveling of a vehicle.SOLUTION: Tire air pressure data equivalent to a predetermined number of times of detection or the alarm threshold is prestored on a transmitter side, and a value obtained by lowering pressure by an alarm detection decompression rate from the maximum value of the prestored tire air pressure is set as the alarm threshold or the maximum value of the prestored alarm threshold is set as the alarm threshold. The tire air pressure detected on the transmitter side is compared with the set alarm threshold to detect the decrease of the tire air pressure. Thus, the alarm about the decrease of the tire air pressure can be surely given on the basis of the alarm threshold following the change of the air pressure in the tire, which is caused by the traveling of the vehicle.

Description

  The present invention relates to a tire air pressure detecting device that detects a decrease in tire air pressure of a wheel attached to a vehicle.

  Conventionally, various direct-type tire pressure detection devices have been proposed (see, for example, Patent Document 1). In the direct tire pressure detecting device, a transmitter equipped with a sensor such as a pressure sensor is directly attached to a wheel side to which a tire is attached. In addition, an antenna and a receiver are provided on the vehicle body side. When a data signal indicating the detection result of the sensor is transmitted from the transmitter, the data signal is received by the receiver via the antenna and received. The tire pressure is detected from the obtained data.

  In this type of tire pressure detection device, when a data signal is sent from the transmitter at the transmission timing of every fixed transmission cycle, the tire pressure is obtained on the receiver side, and the obtained tire pressure falls below a certain alarm threshold value. And the form of warning the fall of tire air pressure is taken.

JP 2007-015491 A

  However, in the conventional tire air pressure detection device, the alarm threshold value used when detecting the decrease in the tire air pressure is a constant value, and the alarm threshold value that varies with time is not applied.

  In recent years, the United Nations Economic Commission for Europe (UNECE) has been examining the regulation of wearing tire pressure detectors from both safety and environmental perspectives. As a specific legal requirement, it is required to set an alarm threshold value corresponding to the pressure value after the increase when the tire air pressure increases due to traveling of the vehicle or the like. As a technique for realizing this, it is conceivable to obtain an ideal pressure value corresponding to a temperature change using a gas state equation, that is, Boyle's law, and to compare this ideal pressure value with an alarm threshold value. However, when temperature data in the tire is used, it is difficult to realize this method because of a large temperature error.

  As a method for solving this problem, it is conceivable to vary the alarm threshold value on the receiver side based on the tire pressure obtained from the received data. However, since it is difficult for the receiver side to reliably receive all the radio waves transmitted from the transmitter every time, when using the received data, an alarm threshold that deviates from the originally desired value may be set. There is sex. This will be described with reference to a timing chart showing the relationship between the actual tire pressure shown in FIG. 7 and the alarm threshold set based on the received data.

  As shown in FIG. 7, data indicating actual tire pressure measured at a predetermined time interval on the transmitter side is transmitted to the receiver side at the transmission timing. On the receiver side, an alarm threshold is set based on the received data at this time. At this time, it is sufficient that the data transmitted from the transmitter side can be received by the receiver side every time, but the data may not be received. For this reason, like the ideal alarm threshold indicated by the broken line in the figure, the alarm threshold should ideally change following the actual tire pressure, whereas the actual alarm threshold indicated by the bold line in the figure. As described above, the alarm threshold value may not be able to follow the actual tire pressure. In such a case, the tire pressure decreases, the tire pressure falls below the ideal alarm threshold, and if the tire pressure should be alarmed if it should be, the tire pressure at that time is above the actual alarm threshold. For this reason, a situation where no alarm is issued may occur.

  The present invention has been made in view of the above points, and it is an object of the present invention to provide a tire air pressure detection device that can more reliably warn of a decrease in tire air pressure based on an alarm threshold value that follows a change in air pressure in the tire as the vehicle travels. .

  In order to achieve the above object, in the invention according to claim 1, the transmitter (2) acquires the tire pressure for each detection cycle, and the maximum value of the tire pressure for a predetermined number of detections before the current detection cycle. The first alarm threshold value is set to the value obtained by reducing the pressure by a predetermined rate or the maximum value of the value by which the pressure is reduced by a predetermined rate from each of the tire air pressures for a predetermined number of detections, and acquired at the current detection cycle. If the tire pressure is less than or equal to the first alarm threshold, it is determined that the tire pressure has decreased, data indicating that the tire pressure has decreased is transmitted to the receiver (3), and the receiver (3 ) Is characterized by detecting a decrease in tire air pressure and outputting an alarm signal when data indicating that the tire air pressure has decreased is transmitted from the transmitter (2).

  In this way, the transmitter (2) side reduces the pressure by a predetermined rate from the maximum value of the tire pressure for a predetermined number of detections, or applies a pressure by a predetermined rate from each of the tire pressures for a predetermined number of detections. The maximum value of the reduced values is set as the first alarm threshold value. Then, a decrease in tire air pressure is detected by comparing the tire air pressure detected on the transmitter (2) side with the first alarm threshold value. Accordingly, it is possible to more reliably warn of a decrease in tire air pressure based on the first alarm threshold value following the change in air pressure in the tire as the vehicle travels.

  In addition, the first alarm threshold can be set in consideration of a margin. That is, as described in claim 2, a value obtained by adding a margin to a value obtained by reducing the pressure by a predetermined rate from the maximum value of the tire air pressure for a predetermined number of detections before the current detection cycle, or a predetermined value A maximum value of a value obtained by adding a margin to a value obtained by reducing the pressure by a predetermined ratio from each of the tire air pressures corresponding to the number of times of detection may be set as the first alarm threshold.

  For example, as described in claim 3, it is preferable that the transmitter (2) transmits data indicating that the tire air pressure is decreasing together with data indicating the tire air pressure at the transmission timing. By doing in this way, the power consumption in a transmitter (2) can be reduced more compared with the case where each data is transmitted at a different timing.

  In this case, in the invention described in claim 4, it is preferable to transmit data indicating that the tire air pressure is decreased at a plurality of transmission timings from the transmitter (2). By doing in this way, it becomes possible to receive the data which shows that tire pressure is falling with a receiver (3) more certainly.

  Furthermore, as described in claim 5, in the transmitter (2), when it is determined that the tire air pressure has decreased with a predetermined transmission cycle as a transmission timing, the transmission cycle is set to be lower than that before the determination. It is preferable to shorten and increase the transmission frequency. By increasing the transmission frequency in this way, it is possible to transmit to the receiver side that the tire air pressure has been reduced more quickly and reliably.

  In the invention according to claim 6, the receiver (3) stores a second alarm threshold value that defines a lower limit value of the tire pressure provided separately from the first alarm threshold value, and from the transmitter (2). Even when the tire pressure indicated by the data indicating the tire pressure sent is equal to or lower than the second alarm threshold, a decrease in the tire pressure is detected and an alarm signal is output.

  In this manner, the second alarm threshold value is stored on the receiver (3) side, and a decrease in tire air pressure can be detected even when the tire air pressure becomes equal to or lower than the second alarm threshold value. In this way, when the tire pressure gradually decreases, it is possible to detect a decrease in tire air pressure on the receiver (3) side.

  In the invention according to claim 7, the receiver (3) stores the pressure value of the tire air pressure at the time of alarm generation when the decrease in tire air pressure is detected and outputs an alarm signal, and the transmitter (2) after the alarm is generated. When the tire pressure indicated by the tire pressure data sent from the vehicle exceeds the value obtained by adding the hysteresis value for releasing the alarm to the pressure value at the time of alarm generation, the alarm (4) is instructed to cancel the alarm. A release signal is output.

  In this way, at the receiver (3), the tire pressure indicated by the tire pressure data sent from the transmitter (2) after the alarm is generated is added to the alarm release hysteresis value to the pressure value at the time of the alarm occurrence. When it is determined that the measured value has been exceeded, the alarm display by the display (4) can be canceled.

  In the invention according to claim 8, the transmitter (2) stores the pressure value of the tire air pressure at the time of alarm occurrence when it is determined that the tire air pressure has decreased, and the tire air pressure acquired after the alarm occurrence is stored. When the value obtained by adding the hysteresis value for alarm release to the pressure value at the time of alarm occurrence is exceeded, data indicating alarm release is sent to the receiver (3), and the receiver (3) When data indicating the alarm release is sent from, a release signal for instructing the release of the alarm is output to the display (4).

  Thus, when it is determined by the transmitter (2) that the tire air pressure acquired after the alarm is generated exceeds the value obtained by adding the alarm cancellation hysteresis value to the pressure value at the time of the alarm occurrence, the indicator (4 ) May be canceled.

  In the invention according to claim 9, the transmitter (2) has the tire pressure corresponding to the predetermined number of detection times used for setting the first alarm threshold value when the alarm is generated, when it is determined that the tire air pressure is decreasing. When the tire pressure acquired after alarm occurrence exceeds the stored maximum value plus hysteresis value for alarm cancellation, data indicating alarm cancellation is sent to receiver (3). The receiver (3) is characterized in that, when data indicating alarm cancellation is sent from the transmitter (2), the receiver (3) outputs a cancellation signal instructing cancellation of the alarm to the display (4). .

  Thus, when it is determined by the transmitter (2) that the tire air pressure acquired after the alarm is generated exceeds the value obtained by adding the hysteresis value for alarm cancellation to the stored maximum value, the display (4) The alarm display may be canceled.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

1 is a block diagram showing an overall configuration of a tire air pressure detection device according to a first embodiment of the present invention. (A), (b) is the figure which showed the block configuration of the transmitter 2 and the receiver 3 with which a tire pressure detection apparatus is equipped, respectively. It is the flowchart which showed the detail of the process which the control part 22a of the transmitter 2 performs among tire pressure detection apparatuses. It is the flowchart which showed the detail of the alarm determination which the control part 32b of the receiver 3 performs among tire pressure detection apparatuses. It is the flowchart which showed the detail of the alarm cancellation | release determination process which the control part 32b of the receiver 3 performs among tire pressure detection apparatuses. It is a timing chart showing operation at the time of performing alarm judgment processing and warning cancellation judgment processing. 4 is a timing chart showing the relationship between actual tire pressure and an alarm threshold set based on received data.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an overall configuration of a tire air pressure detecting device according to an embodiment of the present invention. The upper direction in the drawing of FIG. 1 corresponds to the front of the vehicle 1, and the lower direction of the drawing corresponds to the rear of the vehicle 1. With reference to this figure, the tire pressure detecting device in the present embodiment will be described.

  As shown in FIG. 1, the tire air pressure detection device is attached to a vehicle 1 and includes a transmitter 2, a receiver 3, and a display 4.

  As shown in FIG. 1, the transmitter 2 is attached to each wheel 5 a to 5 d in the vehicle 1, detects the air pressure of the tire attached to the wheels 5 a to 5 d, and displays the detection result. The detection signal data shown is stored in a transmission frame and transmitted. The receiver 3 is attached to the vehicle body 6 side of the vehicle 1 and receives a frame transmitted from the transmitter 2 and performs various processes and computations based on data stored therein. The tire pressure is to be calculated. 2A and 2B show block configurations of the transmitter 2 and the receiver 3.

  As shown in FIG. 2A, the transmitter 2 includes a sensing unit 21, a microcomputer 22, a battery 23, and a transmission antenna 24.

  The sensing unit 21 includes, for example, a diaphragm type pressure sensor and outputs a detection signal corresponding to the tire pressure. The sensing unit 21 detects the tire pressure at every predetermined detection cycle based on a command from the microcomputer 22.

  The microcomputer 22 is a well-known computer having a control unit 22a, a transmission unit 22b, and the like, and executes predetermined processing according to a program stored in a memory (not shown) in the control unit 22a.

  The control unit 22a receives a detection signal indicating the tire air pressure from the sensing unit 21 every predetermined detection cycle, and performs signal processing on the detection signal to obtain the tire air pressure. And it stores in the frame together with the ID information of each transmitter 2 as data indicating the acquired tire pressure, and then sends the frame to the transmitter 22b. The process of sending a signal to the transmission unit 22b is executed every predetermined transmission cycle according to the program. One cycle of the transmission cycle is, for example, one cycle or a plurality of cycles of the detection cycle in the sensing unit 21, and the tire pressure data acquired at that time is transmitted each time detection is performed once or a plurality of times. I am doing so.

  In the present embodiment, when the tire pressure is acquired for each detection cycle, the control unit 22a calculates a warning threshold value based on the tire pressure, and stores the calculated warning threshold value in the memory (not shown). . For example, a value obtained by lowering the pressure by a predetermined rate (hereinafter, this rate is referred to as an alarm detection pressure reduction rate) with respect to the tire air pressure at that time is set as the alarm threshold. For example, the alarm detection decompression rate is set to 20%.

  However, simply setting the alarm threshold as a value that reduces the pressure from the tire pressure at that time by the alarm detection pressure reduction rate will always result in the alarm threshold being lower than the tire pressure. It cannot be detected. For this reason, the tire pressure data for a predetermined number of detections (for a predetermined period) or the alarm threshold value is stored in the memory, and the pressure is reduced by the alarm detection pressure reduction rate from the stored maximum value of the tire pressure. Is set as the alarm threshold value, or the maximum value of the stored alarm threshold value is set as the alarm threshold value. The alarm threshold set at this time corresponds to the first alarm threshold in the present invention.

  By doing in this way, the alarm threshold obtained from the maximum value of the tire pressure during the predetermined number of detections, that is, the maximum value of the alarm threshold during the predetermined number of detections is set as the alarm threshold, and the tire pressure at that time is reduced. Can be used for detection. For this reason, it is possible to accurately detect a decrease in tire air pressure. Note that the alarm threshold value may be set to a value obtained by reducing the tire pressure at that time by a constant alarm detection pressure reduction rate determined by law, but an error amount such as a detection error in the sensing unit 21 may be set. A margin may be set in anticipation of. For example, a value that is reduced at a rate lower than the alarm detection decompression rate determined by the law or a value that is reduced by the alarm detection decompression rate determined by the law + α [kPa] is set to detect a decrease in tire air pressure. An alarm threshold value may be set so that the value is easily set.

  And in this embodiment, if the control part 22a detects the fall of a tire air pressure as mentioned above, it will give the data which show that the tire air pressure fell in the flame | frame in which the data which show a tire air pressure are stored, The frame storing these data is sent to the transmission unit 22b at the transmission timing. The data indicating that the tire pressure has decreased may be given only once to the frame in which the data indicating the tire pressure is stored, but is the received frame reliably received by the receiver 3? Since it does not understand, it is preferable to give it for a certain period (multiple times). By doing in this way, it can be made to receive with the receiver 3 more reliably.

  The transmission unit 22 b functions as an output unit that transmits a frame transmitted from the control unit 22 a to the receiver 3 through the transmission antenna 24.

  The battery 23 supplies power to the control unit 22a and the like. Upon receiving power supply from the battery 23, the battery 23 collects data indicating tire pressure in the sensing unit 21 and performs various calculations in the control unit 22a. Etc. are executed.

  The transmitter 2 configured in this way is attached to an air injection valve in each of the wheels 5a to 5d, for example, and is arranged so that the sensing unit 21 is exposed inside the tire. Thereby, the tire air pressure of the corresponding wheel is detected, and the frame is transmitted every predetermined transmission cycle (for example, every minute) through the transmission antenna 24 provided in each transmitter 2.

  As shown in FIG. 2B, the receiver 3 includes an antenna 31 and a microcomputer 32.

  The antenna 31 is one or a plurality of antennas that collectively receive frames transmitted from the transmitters 2, and is fixed to the vehicle body 6.

  The microcomputer 32 is a well-known computer having a receiving unit 32a, a control unit 32b, and the like, and executes predetermined processing according to a program stored in a memory (not shown) in the control unit 32b.

  The receiving unit 32a functions as an input unit that receives a frame from each transmitter 2 received by each antenna 31 and sends the frame to the control unit 32b.

  The control unit 32b receives the frame transmitted from the receiving unit 32a, and if the data stored in the frame includes data indicating that the tire air pressure has decreased, an alarm for instructing an alarm for a decrease in tire air pressure. The signal is output to the display 4. At this time, if the received frame includes data indicating that the tire air pressure has decreased even once, an alarm signal may be immediately output from the control unit 32b to the display unit 4, but multiple times. In the case of coincidence, that is, when data indicating that the tire air pressure has decreased is included in the frame continuously a plurality of times, the fact may be output from the control unit 32b to the display 4 for the first time. In this way, it is possible to prevent the tire pressure drop from being erroneously displayed based on indeterminate data such as erroneous data or other vehicle data.

  Further, the control unit 32b determines whether or not the transmitter 2 determines based on the data indicating the tire pressure stored in the received frame, that is, the received pressure value that is the value of the received tire pressure (hereinafter referred to as the received pressure). Separately, it is determined again that the tire air pressure is decreasing. For example, a value obtained by reducing a warning detection pressure reduction rate (for example, 20%) with respect to a recommended tire pressure determined for each vehicle type (hereinafter referred to as a vehicle recommended pressure) is set as a warning threshold, and a received pressure value is equal to or lower than the warning threshold. If so, it is determined that the tire pressure has decreased. The alarm threshold value set at this time is a value that defines the lower limit value of the tire air pressure, and corresponds to the second alarm threshold value in the present invention.

  Even when it is determined that the tire air pressure has decreased in this way, an alarm signal for instructing an alarm for a decrease in tire air pressure is output to the display 4. Thereby, the indicator 4 is informed that the tire pressure of any of the wheels 5a to 5d has decreased. Also at this time, when the tire pressure data included in the received frame is continuously lower than the alarm threshold value a plurality of times, this may be output from the control unit 32b to the display 4 for the first time. In this way, it is possible to prevent the tire pressure drop from being erroneously displayed based on indeterminate data such as erroneous data or other vehicle data.

  In addition, although the case where the alarm threshold value is set based on the vehicle recommended pressure in the receiver 3 has been described here, the alarm threshold value set on the receiver 3 side can be set to the user set pressure set by the user himself / herself. . However, even in this case, the lower limit value of the alarm threshold that can be set as the user set pressure is set to a value that is set based on the vehicle recommended pressure, so that it is at least equal to or lower than the alarm threshold set based on the vehicle recommended pressure. An alarm can be issued when the tire air pressure drops.

  On the other hand, the receiving unit 32a is configured to release the alarm when a predetermined release condition is satisfied after sending a warning signal instructing a warning of a decrease in tire air pressure to the display 4. For example, in the receiving unit 32a, the tire air pressure when the alarm is given (hereinafter referred to as a pressure value when the alarm is generated) is stored in a memory (not shown) in the microcomputer 32 and transmitted from the transmitter 2 after the alarm. When the tire air pressure stored in the frame exceeds the value obtained by adding a predetermined alarm release hysteresis value ΔP to the pressure value at the time of alarm occurrence, the alarm release is performed. The alarm cancellation hysteresis value ΔP at this time may be a constant value or a value that differs for each vehicle.

  As shown in FIG. 1, the display 4 is arranged at a place where the driver can visually recognize, and is configured by an alarm lamp installed in an instrument panel in the vehicle 1, for example. For example, when an alarm signal instructing an alarm for a decrease in tire air pressure is sent from the control unit 32b in the receiver 3, the display device 4 displays an indication to that effect so that the driver is informed of a decrease in tire air pressure. Do.

  As described above, the tire air pressure detection device in the present embodiment is configured.

  Subsequently, an operation example of the tire pressure detection device configured as described above will be described. FIG. 3 is a flowchart showing details of processing executed by the control unit 22a of the transmitter 2 in the tire pressure detecting device. 4 and 5 are flowcharts showing details of the alarm determination and alarm release determination processing executed by the control unit 32b of the receiver 3 in the tire air pressure detection device. With reference to these drawings, an operation example of the tire pressure detecting device will be described.

  First, the control unit 22a of the transmitter 2 executes various processes shown in the flowchart of FIG. 3 for each predetermined detection cycle. Here, a case where the detection cycle and the transmission cycle are the same will be described as an example. Therefore, the timing at which this process is executed is the transmission timing at which the transmitter 2 transmits a frame to the receiver 3.

  In step 100, the tire pressure is sensed by the sensing unit 21. Specifically, when a signal instructing the sensing unit 21 to perform sensing is output, tire pressure is sensed by the sensing unit 21 according to the command, and a detection signal is sent from the sensing unit 21. Therefore, it receives it and processes the signal to get the tire pressure. And the acquired tire pressure is memorized.

  In step 110, tire pressure data corresponding to a predetermined number of detection times is read out, and the maximum value is extracted. Here, the predetermined number of detections is 3, and the latest three data, that is, the tire air pressure acquired from the current detection cycle up to the detection cycle three times before is read, and the maximum value is extracted. ing. Then, a value obtained by reducing the pressure by the alarm detection decompression rate with respect to the maximum value is set as the alarm threshold, and it is determined whether or not the tire air pressure in the current detection cycle acquired in step 100 is equal to or less than the alarm threshold. judge. Here, for example, the alarm detection pressure reduction rate is set to 20%, and the pressure value of 80% of the maximum value of the tire pressure of the latest three data is used as the alarm threshold value.

  If a negative determination is made here, the tire air pressure has not decreased to a value to be alarmed, so the process proceeds to step 120, the tire air pressure data acquired in step 100 is stored in a frame, and the frame is transmitted via the transmission unit 22b. To the receiver 3 side. On the other hand, if an affirmative determination is made here, the tire air pressure has decreased to a value to be alarmed, so the process proceeds to step 130, and data indicating that the tire air pressure has decreased together with the tire air pressure data acquired in step 100 is displayed. The frame is stored in the frame, and the frame is transmitted to the receiver 3 via the transmitter 22b.

  Thereafter, the process proceeds to step 140, where the currently acquired tire pressure data is stored as the tire pressure data for a predetermined number of detection times, and the oldest data is erased and the processing is terminated. In this manner, a frame storing tire pressure data or data indicating that the tire pressure has decreased is transmitted from the transmitter 2 to the receiver 3.

  On the other hand, for the receiver 3, when an ignition switch (not shown) is switched from OFF to ON, the control unit 32b of the receiver 3 is turned on, and a frame transmitted from the transmitter 2 is received to make an alarm determination. After the process is performed and the alarm determination is performed, an alarm release determination process is also performed.

  First, as shown in FIG. 4, it is determined whether or not data reception is performed in step 200 as an alarm determination process. If a frame transmitted from the transmitter 2 is received, an affirmative determination is made and the process proceeds to step 210. If not received, the process waits until it is received.

  Subsequently, in step 210, it is determined whether or not the data stored in the received frame includes data indicating that the tire air pressure has decreased. If a negative determination is made here, the process proceeds to step 220, in which it is determined whether or not the received pressure value indicated in the tire pressure data stored in the received frame is equal to or less than an alarm threshold set on the receiver 3 side. judge. Here, for example, the alarm detection pressure reduction rate is set to 20%, and a pressure value of 80% of the vehicle recommended pressure is used as the alarm threshold value. If a negative determination is also made here, the tire air pressure has not decreased, and the processing is terminated as it is.

  On the other hand, if an affirmative determination is made in either step 210 or step 220, the process proceeds to step 230. In step 230, an alarm determination is made, and an alarm signal for instructing an alarm of a decrease in tire air pressure is output from the receiver 3 to the display 4. As a result, the indicator 4 indicates that the tire air pressure has decreased, and the driver is warned of the tire air pressure decrease. At the same time, the tire air pressure at the time of alarm generation is stored and used in the alarm cancellation determination process to be performed in the future.

  Note that the alarm determination process shown in FIG. 4 is performed every time a frame transmitted from the transmitter 2 is received. Therefore, even if the tire pressure is lowered and the alarm determination is made, the alarm determination process is transmitted from the transmitter 2. When a frame to be received is received, it is continuously executed again.

  The alarm release determination process is executed, for example, when the pressure value at the time of alarm generation is stored in the alarm determination process. As shown in FIG. 5, in the alarm cancellation determination process, it is determined whether or not data reception is performed in step 300. If a frame transmitted from the transmitter 2 is received, an affirmative determination is made and the process proceeds to step 310. If not received, the process waits until it is received.

  Subsequently, in step 310, it is determined whether or not an alarm cancellation condition is satisfied. For example, here, the alarm release hysteresis value ΔP is added to the alarm pressure value stored in the receiver 3 as the received pressure value indicated in the tire pressure data stored in the received frame. It is determined whether the value is exceeded. If an affirmative determination is made here, the routine proceeds to step 320 where an alarm cancellation determination is made, and a release signal instructing the receiver 3 to release the alarm is output to the display 4. Thereby, the indication that the tire air pressure has decreased on the display 4 is released. At the same time, the stored pressure value at the time of alarm occurrence is cleared, and the process ends.

  FIG. 6 is a timing chart showing the operation when the alarm determination process and the alarm release determination process as described above are performed. In the drawing, a circle represents a detection cycle in which sensing by the transmitter 2 is performed.

  First, as shown in FIG. 6, the tire pressure increases as the vehicle travels between time points T <b> 1 and T <b> 2 from the state where the tire pressure at the time of sensing coincides with the recommended vehicle pressure at time point T <b> 0. And during that rise, the maximum value of tire pressure in the three most recent data always rises. For this reason, the alarm threshold also rises accordingly. Further, the tire air pressure detected at time T3 is compared with an alarm threshold value determined based on the maximum value of the tire air pressure of the latest three data between times T1 and T2. In the example shown in this figure, the tire air pressure detected at time T3 is not below the alarm threshold. Therefore, at the transmission timing at time T3, only tire pressure data is stored in the frame and transmitted.

  After that, for example, tire pressure may decrease depending on the vehicle running state etc. as at time T2 to T4, but since the alarm threshold is set based on the maximum value of tire pressure of the latest three data, Even in this case, the alarm threshold does not decrease. For example, at time T5, when the maximum value of the tire pressure of the three most recent data falls below the previous value, the alarm threshold is also lowered at that time.

  Further, for example, as shown at time T6, when the detected tire pressure falls below the alarm threshold set based on the maximum value of the tire pressure of the three most recent data, at this transmission timing, in addition to the tire pressure data, the tire pressure data Data indicating the decrease is stored in the frame and transmitted. As a result, the receiver 3 receives data indicating a decrease in tire air pressure and causes the display 4 to display that the tire air pressure has decreased.

  On the other hand, the alarm threshold set by the transmitter 2 is basically a value based on the maximum value of the tire pressure of the latest three data. For this reason, although not shown in FIG. 6, if the tire air pressure gradually decreases, even if the tire air pressure becomes equal to or less than the value that is reduced by the alarm detection pressure reduction rate from the vehicle recommended pressure, the latest 3 The alarm threshold value based on the maximum value of tire pressure in the data may not fall below. Therefore, on the receiver 3 side, by comparing the received tire pressure with the alarm threshold set based on the recommended vehicle pressure, even if the tire pressure gradually decreases, the tire pressure can be reliably detected. It becomes possible to do.

  As described above, in the tire pressure detection device according to the present embodiment, the tire pressure data or alarm threshold value for the predetermined number of detections is stored on the transmitter 2 side, and the stored maximum value of the tire pressure is stored. From the above, a value obtained by reducing the pressure by the alarm detection decompression rate is set as the alarm threshold value, or the stored maximum value of the alarm threshold value is set as the alarm threshold value. Then, a decrease in tire air pressure is detected by comparing the tire air pressure detected on the transmitter 2 side with a set alarm threshold value. Accordingly, it is possible to more reliably warn of a decrease in tire air pressure based on the alarm threshold value that follows the change in air pressure in the tire as the vehicle travels.

  On the receiver 3 side, a warning threshold value based on the recommended vehicle pressure is set, and the tire pressure indicated by the received tire pressure data is compared with the warning threshold value. As a result, even when the tire air pressure gradually decreases, it is possible to reliably warn of the tire air pressure decrease.

  Furthermore, the alarm threshold value based on the recommended vehicle pressure can be set on each transmitter 2 side. However, since the recommended vehicle pressure is a tire pressure that is recommended differently for each vehicle type, if the recommended vehicle pressure is set on the transmitter 2 side, it is stored in the microcomputer 22 of the transmitter 2 for each vehicle type. The contents will be different. For this reason, the alarm threshold value based on the recommended vehicle pressure is set on the receiver 3 side, and the alarm threshold value and the tire air pressure are compared, so that the microcomputer 22 of the transmitter 2 differs depending on the vehicle type. The need to memorize the contents can be eliminated, and more versatility can be provided.

(Other embodiments)
(1) In the above embodiment, when a decrease in tire air pressure is detected, data indicating that the tire air pressure has decreased is stored in a frame in which data indicating the tire air pressure is stored, and the frame is received at the transmission timing. It sends to the machine side. On the other hand, the data indicating that the tire pressure has decreased is stored in a frame different from the frame including the data indicating the tire pressure, and the frame is simultaneously or different from the frame storing the data indicating the tire pressure. It may be transmitted to the receiver side at the timing.

  In this case, when transmitting a frame storing data indicating that the tire air pressure has decreased at a different timing from the frame storing the data indicating the tire pressure, it is more reliable if it is repeatedly performed. It can be transmitted to the receiver side that the tire pressure has decreased. More preferably, if a frame storing data indicating that the air pressure has decreased is transmitted at a high frequency with a transmission cycle shorter than the transmission cycle of the frame storing the tire air pressure data, it is faster and more reliable. It can be transmitted to the receiver side that the tire pressure has decreased.

  Also, when transmitting a frame storing data indicating that the tire pressure has decreased at the same time as a frame storing data indicating tire pressure, the transmission cycle is shorter than before the detection of the decrease in tire pressure. However, it can be transmitted more frequently. Even in this case, it is possible to more reliably inform the receiver that the tire air pressure has decreased.

  As described above, data indicating that the tire pressure has decreased can be transmitted at the same time as or different from the data indicating the tire pressure. However, the transmitter 2 wants to reduce power consumption as much as possible, so that it is performed at the same time. Is preferred.

  (2) In the above embodiment, the alarm cancellation determination process is performed on the receiver 3 side, but may be performed on the transmitter 2 side. Specifically, when it is determined that the tire air pressure has decreased in the transmitter 2, that is, the pressure value at the time of alarm occurrence is stored, and the tire air pressure detected after the alarm is predetermined with respect to the pressure value at the time of alarm occurrence. When the alarm cancellation hysteresis value ΔP is exceeded, the alarm cancellation may be performed. The alarm cancellation hysteresis value ΔP at this time may be a constant value or a value that differs for each vehicle.

  When the alarm release determination process is performed on the transmitter 2 side as described above, data indicating the alarm release is stored in a frame and transmitted to the receiver 3 in addition to the tire air pressure data when the alarm release determination is performed. . Then, the receiver 3 determines whether or not the received data includes data indicating alarm cancellation, and if included, outputs a cancellation signal that instructs the display 4 to cancel the alarm. In this way, the alarm release determination process can be performed on the transmitter 2 side. Of course, when the data indicating the alarm release is sent from the transmitter 2, it may be sent alone instead of the tire pressure data.

  Further, when the alarm release determination process is performed on the transmitter 2 side, the alarm release condition may be changed. For example, the maximum value of the tire pressure of the three most recent data used for calculation of the alarm threshold when the alarm is generated on the transmitter 2 side (hereinafter referred to as the maximum stored value when the alarm is generated) is stored. Then, when the tire pressure detected thereafter exceeds the maximum stored value at the time of alarm generation, the alarm release determination may be performed.

  (3) The transmitter 2 can measure the transmission timing by itself by incorporating a clock in the control unit 22a. For example, the receiver 3 uses a trigger device at every predetermined period. The trigger signal may be sent to each transmitter 2, and the time when each transmitter 2 receives the trigger signal may be used as a trigger for transmission timing.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Transmitter 3 Receiver 4 Indicator 5a-5d Wheel 6 Car body

Claims (9)

  1. Transmission that is attached to each of a plurality of wheels (5a to 5d) equipped with tires, acquires tire air pressure at the attached wheels (5a to 5d), and transmits data indicating the tire air pressure at the transmission timing Machine (2),
    A receiver (3) that is provided on the vehicle body (6) side, receives data indicating the tire pressure, and outputs a warning signal instructing a warning of a decrease in tire pressure when detecting a decrease in tire pressure;
    In a tire pressure detecting device comprising: a display (4) that issues a warning of a decrease in tire pressure based on the warning signal from the receiver (3),
    The transmitter (2) acquires the tire air pressure for each detection cycle, and a value obtained by reducing the pressure by a predetermined ratio from the maximum value of the tire air pressure for a predetermined number of detections before the current detection cycle, or A maximum value obtained by reducing the pressure by the predetermined ratio from each of the tire pressures for a predetermined number of detection times is set as a first alarm threshold, and the tire air pressure acquired in the current detection cycle is the first alarm threshold. If it is below, it is determined that the tire air pressure has decreased, and data indicating that the tire air pressure has decreased is transmitted to the receiver (3).
    The receiver (3) detects a decrease in the tire air pressure and outputs the alarm signal when data indicating that the tire air pressure has decreased is transmitted from the transmitter (2). A tire air pressure detecting device.
  2. Transmission that is attached to each of a plurality of wheels (5a to 5d) equipped with tires, acquires tire air pressure at the attached wheels (5a to 5d), and transmits data indicating the tire air pressure at the transmission timing Machine (2),
    A receiver (3) that is provided on the vehicle body (6) side, receives data indicating the tire pressure, and outputs a warning signal instructing a warning of a decrease in tire pressure when detecting a decrease in tire pressure;
    In a tire pressure detecting device comprising: a display (4) that issues a warning of a decrease in tire pressure based on the warning signal from the receiver (3),
    The transmitter (2) acquires the tire air pressure for each detection cycle, and with respect to a value obtained by reducing the pressure by a predetermined ratio from the maximum value of the tire air pressure for a predetermined number of detections before the current detection cycle. A maximum value of a value obtained by adding a margin to a value obtained by adding a margin or a value obtained by reducing the pressure by a predetermined rate from each tire air pressure for a predetermined number of detection times is set as the first alarm threshold value, If the tire air pressure acquired in the current detection cycle is less than or equal to the first alarm threshold, it is determined that the tire air pressure has decreased, and data indicating that the tire air pressure has decreased is received by the receiver ( 3)
    The receiver (3) detects a decrease in the tire air pressure and outputs the alarm signal when data indicating that the tire air pressure has decreased is transmitted from the transmitter (2). A tire air pressure detecting device.
  3.   The tire according to claim 1 or 2, wherein the transmitter (2) transmits data indicating that the tire air pressure is reduced together with data indicating the tire air pressure at the transmission timing. Air pressure detection device.
  4.   The tire pressure detection device according to claim 3, wherein the transmitter (2) transmits data indicating that the tire pressure is reduced at a plurality of times of the transmission.
  5.   The transmitter (2) uses a predetermined transmission cycle as the transmission timing. When it is determined that the tire air pressure is reduced, the transmitter (2) shortens the transmission cycle and sets the transmission frequency compared to before the determination. The tire pressure detecting device according to claim 4, wherein the tire pressure detecting device is made high.
  6.   The receiver (3) stores a second alarm threshold value that is provided separately from the first alarm threshold value and defines a lower limit value of the tire air pressure, and the tire air pressure sent from the transmitter (2) 6. The alarm signal is output by detecting a decrease in the tire air pressure even when the tire air pressure indicated by the data indicating the tire pressure is less than or equal to the second alarm threshold value. The tire pressure detecting device according to one.
  7.   The receiver (3) stores the pressure value of the tire air pressure at the time of alarm generation when the decrease in tire air pressure is detected and outputs the alarm signal, and is sent from the transmitter (2) after the alarm is generated. When the tire air pressure indicated by the tire air pressure data exceeds a value obtained by adding an alarm canceling hysteresis value to the pressure value at the time of the alarm generation, an instruction to cancel the alarm is given to the display (4). The tire pressure detecting device according to any one of claims 1 to 6, wherein a release signal is output.
  8. The transmitter (2) stores a pressure value of the tire air pressure when an alarm is generated when it is determined that the tire air pressure is reduced, and the tire air pressure acquired after the alarm is generated is when the alarm is generated. When the value obtained by adding the alarm release hysteresis value to the pressure value is exceeded, data indicating the alarm release is sent to the receiver (3),
    When the receiver (3) receives data indicating the alarm cancellation from the transmitter (2), the receiver (3) outputs a cancellation signal that instructs the display (4) to cancel the alarm. The tire air pressure detecting device according to any one of claims 1 to 6, characterized in that:
  9. The transmitter (2) sets the maximum value of the tire pressure for the predetermined number of detection times used for setting the first alarm threshold value when the alarm is generated, which is when it is determined that the tire pressure is reduced. When the tire air pressure acquired after the alarm is generated exceeds a value obtained by adding a hysteresis value for alarm cancellation to the stored maximum value, data indicating alarm cancellation is sent to the receiver (3). ,
    When the receiver (3) receives data indicating the alarm cancellation from the transmitter (2), the receiver (3) outputs a cancellation signal that instructs the display (4) to cancel the alarm. The tire air pressure detecting device according to any one of claims 1 to 6, characterized in that:
JP2011034730A 2011-02-21 2011-02-21 Tire air pressure detector Pending JP2012171463A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2011034730A JP2012171463A (en) 2011-02-21 2011-02-21 Tire air pressure detector

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2011034730A JP2012171463A (en) 2011-02-21 2011-02-21 Tire air pressure detector
DE201210101159 DE102012101159A1 (en) 2011-02-21 2012-02-14 Tire pressure detecting device for vehicle, has transmitter mounted on wheel, which is mounted on tire, where tire pressure of tire is detected by transmitter with detection time, and transmitter data indicating tire pressure is transmitted
KR1020120016841A KR101379606B1 (en) 2011-02-21 2012-02-20 Tire pressure detection apparatus

Publications (1)

Publication Number Publication Date
JP2012171463A true JP2012171463A (en) 2012-09-10

Family

ID=46605141

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2011034730A Pending JP2012171463A (en) 2011-02-21 2011-02-21 Tire air pressure detector

Country Status (3)

Country Link
JP (1) JP2012171463A (en)
KR (1) KR101379606B1 (en)
DE (1) DE102012101159A1 (en)

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03100502U (en) * 1990-02-01 1991-10-21
JPH0781337A (en) * 1993-09-20 1995-03-28 Calsonic Corp Tire strain alarm device
JP2001063326A (en) * 1999-08-31 2001-03-13 Toyota Motor Corp Tire pressure alarm device
JP2001250186A (en) * 2000-03-06 2001-09-14 Denso Corp Tire air pressure monitoring system for vehicle
JP2003246212A (en) * 2001-12-17 2003-09-02 Honda Motor Co Ltd Tire air pressure detecting apparatus
JP2005112056A (en) * 2003-10-06 2005-04-28 Calsonic Kansei Corp Tire position detecting device and tire pressure monitoring system
JP2007015491A (en) * 2005-07-06 2007-01-25 Denso Corp Wheel position detection device and tire pneumatic pressure detection device provided with it
JP2007182111A (en) * 2006-01-05 2007-07-19 Paramount Shokai:Kk Tire internal pressure monitoring system
JP2008024169A (en) * 2006-07-21 2008-02-07 Aisin Seiki Co Ltd Tire air pressure monitoring system
WO2010122610A1 (en) * 2009-04-24 2010-10-28 トヨタ自動車株式会社 Device for monitoring tire air pressure
JP2010254018A (en) * 2009-04-22 2010-11-11 Toyota Motor Corp Tire air-pressure monitoring system

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11334328A (en) * 1998-05-29 1999-12-07 Pacific Ind Co Ltd Tire inflation pressure warning system
JP2005335525A (en) 2004-05-26 2005-12-08 Denso Corp Tire monitoring system

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03100502U (en) * 1990-02-01 1991-10-21
JPH0781337A (en) * 1993-09-20 1995-03-28 Calsonic Corp Tire strain alarm device
JP2001063326A (en) * 1999-08-31 2001-03-13 Toyota Motor Corp Tire pressure alarm device
JP2001250186A (en) * 2000-03-06 2001-09-14 Denso Corp Tire air pressure monitoring system for vehicle
JP2003246212A (en) * 2001-12-17 2003-09-02 Honda Motor Co Ltd Tire air pressure detecting apparatus
JP2005112056A (en) * 2003-10-06 2005-04-28 Calsonic Kansei Corp Tire position detecting device and tire pressure monitoring system
JP2007015491A (en) * 2005-07-06 2007-01-25 Denso Corp Wheel position detection device and tire pneumatic pressure detection device provided with it
JP2007182111A (en) * 2006-01-05 2007-07-19 Paramount Shokai:Kk Tire internal pressure monitoring system
JP2008024169A (en) * 2006-07-21 2008-02-07 Aisin Seiki Co Ltd Tire air pressure monitoring system
JP2010254018A (en) * 2009-04-22 2010-11-11 Toyota Motor Corp Tire air-pressure monitoring system
WO2010122610A1 (en) * 2009-04-24 2010-10-28 トヨタ自動車株式会社 Device for monitoring tire air pressure

Also Published As

Publication number Publication date
DE102012101159A1 (en) 2012-08-23
KR101379606B1 (en) 2014-03-28
KR20120095802A (en) 2012-08-29

Similar Documents

Publication Publication Date Title
US6750761B1 (en) Method for monitoring tire parameters
KR100537739B1 (en) Transmitter of tire condition monitoring apparatus and tire condition monitoring apparatus
US7042348B2 (en) Method for monitoring the tire pressure on vehicles
EP1612060B1 (en) Tire air pressure monitoring system
EP1330371B1 (en) System for measuring pressure and for controlling inflation/deflation for a tyre
US6750762B1 (en) Method and system for resetting tire pressure monitoring system for an automotive vehicle
US6954688B2 (en) Tire status monitoring apparatus
US7543846B2 (en) Air bag device
EP2741928B1 (en) Tire pressure monitoring apparatus and method
US6828905B2 (en) System for monitoring and for signaling by radio the pressure in pneumatic tires on motor vehicles
DE102008006556B4 (en) Wheel condition monitoring system and wheel condition detection device
EP1813447B1 (en) Tire air pressure monitoring system, tire air pressure sensor unit and method of monitoring-controlling tire air pressure
JP2006312342A (en) Wheel position detector and tire pressure detector having the same
EP1359029B1 (en) System and method for tire inflation monitoring system
DE102006038059B4 (en) Automatic detection of a detached remote tire pressure sensor
JP5041005B2 (en) Tire pressure monitoring device
US6999861B2 (en) Tire status monitoring apparatus and receiver therefor
JP2007230416A (en) Wheel position detection device and tire pressure detection device provided with it
JP2004149093A (en) Tire state monitor device
US7821385B2 (en) Detection of vehicle wheel positions using triggering signal including startup command for starting the detection and execution command for calculating reception intensity of triggering signal
EP1878595B1 (en) Tire pressure monitoring method
EP0833756A1 (en) Method of operating a device for monitoring vehicle-tyre pressures and indicating changes in pressure by radio
US20100148949A1 (en) Method and system for associating a tire pressure sensor to a wheel location in an intitiator based tire pressure monitoring system
US6450021B1 (en) Transmitter and transmitting method of tire air pressure monitoring apparatus
US7116217B2 (en) Transmitter and receiver for tire condition monitoring apparatus

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20120718

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20130111

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20130212

A02 Decision of refusal

Free format text: JAPANESE INTERMEDIATE CODE: A02

Effective date: 20140107