JP5594130B2 - Wheel position detecting device and tire air pressure detecting device having the same - Google Patents

Description

  The present invention relates to a wheel position detection device for detecting at which position of a vehicle a wheel is mounted and a direct tire pressure detection device including the wheel position detection device.

  Conventionally, there is a direct type as one of tire pressure detecting devices. In this type of 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 detection signal from the sensor is transmitted from the transmitter, the detection signal is received by the receiver via the antenna, and tire pressure is detected. To be done.

  In such a direct tire pressure detecting device, the wheel to which the transmitter is attached is included in the data transmitted by the transmitter so that it can be determined which wheel the transmitted data is attached to the transmitter. ID information for discrimination is added. Then, the ID information is registered in advance on the receiver side, and when the data sent from the transmitter is received, it is determined which wheel the data is from the received ID information ( For example, see Patent Document 1).

  Also, if the user himself / herself has changed the wheel position, such as tire rotation, and ID information needs to be re-registered, tire pressure detection with a wheel position detection device that can automatically detect it An apparatus is disclosed in Patent Document 2, for example.

  In the wheel position detection device disclosed in Patent Document 2, the trigger device that transmits the trigger signal is arranged on the vehicle body side so that the distance to each corresponding wheel is different, and the reception intensity of the trigger signal received by the transmitter And the distance from the trigger machine to each wheel, the wheel position is detected as to which wheel each transmitter is attached to. Note that the wheel position detection device disclosed in Patent Document 2 can detect which wheel each transmitter is attached to, not only when ID information is used but also when ID information is not used. is there.

Japanese Patent No. 3212311 Japanese Patent No. 4175348

  As described above, if the distance from the trigger machine to each wheel is different, the reception intensity of the trigger signal at the transmitter differs for each wheel, so the wheel to which the transmitter is attached is determined from the magnitude of the reception intensity. be able to.

  However, if the tire is punctured and replaced with a spare tire and the punctured wheel is placed in the trunk, rear seat, etc. and is not in the proper position, the distance between the punctured wheel and the trigger machine is There is a risk that it will be almost the same as the distance.

  In this case, the reception intensity of the trigger signal at the transmitter of the punctured wheel is approximately the same as the reception intensity of the trigger signal at the transmitter of the other wheel, and the distinction between the punctured wheel and the other wheel is different. There is a risk that a punctured wheel may be mistakenly distinguished from other wheels.

The present invention is made in view of the above disadvantages, prevented had you when wheels punctured is not in the normal position, in order to prevent erroneous detection of the wheel position, to determine by mistake a wheel and another wheel punctured It is an object of the present invention to provide a wheel position detection device that can be used and a tire air pressure detection device including the wheel position detection device.

  In order to achieve the above object, according to the first aspect of the present invention, the first control unit (22a) of the transmitter (2) is configured to transmit the measured received intensity data when the air pressure detected by the sensing unit is equal to or lower than a predetermined pressure. Instead, the reception intensity data corresponding to the trigger machine and stored in advance as a value smaller than the reception intensity of the trigger signal received by the transmitter attached to all the wheels at the normal wheel position is transmitted as a transmission frame. It is characterized by being stored in.

According to this, the received intensity data transmitted from the transmitter attached to the punctured wheel is changed to a value smaller than the measured received intensity, rather than the received intensity at the transmitters of all wheels in the normal position. to so, when wheels punctured is not in the normal position, the transmitter and consultation strength comparable other wheels trigger signal in a transmitter of wheels punctured with Do Ri, the wheel and the other wheels punctured it is possible to prevent that you determine by mistake.

  Therefore, according to the present invention, it is possible to prevent erroneous detection of the wheel position when the punctured wheel is not in the normal position, and transmit from the reception intensity of the trigger signal at the transmitter of each of the other wheels in the normal position. The wheel position to which the machine is attached can be accurately determined.

  In invention of Claim 1, the structure of Claims 2-4 is employable, for example.

  Specifically, in the second aspect of the invention, the second control unit (32b) of the receiver has a numerical value range in which the reception intensity represented by the reception intensity data stored in the transmission frame is preset for each wheel. It is characterized by determining whether the transmitter (2) is attached to a plurality of wheels by determining whether or not it belongs to.

  In the invention according to claim 3, there is only one trigger machine (5), and the second controller (32b) has a plurality of reception strengths represented by reception strength data stored in the transmission frame. It is characterized by determining to which of the plurality of wheels the transmitter (2) is attached by determining whether or not each wheel belongs to a preset numerical range.

In the invention according to claim 4, the plurality of wheels are two front wheels (6a, 6b) and two rear wheels (6c, 6d).
The trigger machine includes a first trigger machine (5a) arranged on the two rear wheels side with respect to the two front wheels and a second trigger machine (5b) arranged on the two front wheels side with respect to the two rear wheels. Configured with
Both the first trigger machine and the second trigger machine are arranged offset in the same direction with respect to a center line that divides the vehicle body symmetrically,
The second control unit (32b) of the receiver
When a trigger signal is output from the first trigger device, it is determined whether or not the reception strength represented by the reception strength data stored in the transmission frame transmitted from the transmitter belongs to a first numerical range set in advance. As a result, it is determined that the wheel to which the transmitter is attached is the wheel (6d) closer to the first trigger machine among the two rear wheels, and whether the wheel belongs to the preset second numerical range. By judging whether or not, the wheel to which the transmitter is attached is the wheel (6c) on the side farther from the first trigger machine in the two rear wheels and the wheel on the side closer to the first trigger machine in the two front wheels. (6b)
When a trigger signal is output from the second trigger device, it is determined whether or not the reception strength represented by the reception strength data stored in the transmission frame transmitted from the transmitter belongs to a preset third numerical range. Thus, it is determined that the wheel to which the transmitter is attached is the wheel (6b) on the side closer to the second trigger machine among the two front wheels, and whether or not it belongs to the preset fourth numerical range. By determining whether the wheel to which the transmitter is attached is the wheel (6a) on the side farther from the second trigger machine among the two front wheels and the wheel on the side closer to the second trigger machine in the two rear wheels ( 6d)
Based on these determination results, the transmitter attached to the wheel (6c) on the side farther from the first trigger machine out of the two rear wheels, and the wheel on the side farther from the second trigger machine (6a in the two front wheels) ) To identify the transmitter attached.

  Received intensity transmitted from the transmitter attached to the punctured wheel when determining which of the plurality of wheels the transmitter is attached to as in the inventions of claims 2 to 4 By changing the data to a value smaller than the reception intensity at the transmitter of all wheels in the normal position, the reception intensity at the punctured wheel does not belong to the numerical range preset for each wheel. Can be. Therefore, erroneous detection of the wheel position when the punctured wheel is not at the proper position can be prevented.

Moreover, in invention of Claim 5, it is a tire air pressure detection apparatus provided with the wheel position detection apparatus as described in any one of Claim 1 thru | or 4,
The transmitter outputs a detection signal related to tire air pressure from the sensing unit (21), and after the detection signal of the sensing unit is signal-processed by the first control unit, it is transmitted via the transmission unit. ,
The receiver is characterized in that, in the second controller, the air pressures of the tires provided on each of the plurality of wheels are obtained based on the detection signal. According to this, there exists an effect similar to the invention of Claims 1-4.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

1 is a block diagram illustrating an overall configuration of a tire air pressure detection device to which a wheel position detection device according to a first embodiment is applied. It is the figure which showed the block configuration of the transmitter and receiver of the tire pressure detection apparatus shown in FIG. It is a flowchart of the reception intensity data selection process which the control part of a transmitter performs. It is a block diagram which shows the whole structure of the tire pressure detection apparatus with which the wheel position detection apparatus in 2nd Embodiment was applied.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings in order to simplify the description.

(First embodiment)
FIG. 1 is a block diagram showing the overall configuration of a tire air pressure detection device to which the wheel position detection device in the present embodiment is applied. 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.

  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, a display 4, and a trigger device 5.

  The transmitter 2 is attached to each of the wheels 6a to 6d in the vehicle 1. The transmitter 2 detects the air pressure of the tire attached to the wheels 6a to 6d, and stores detection signal data indicating the detection result in the transmission frame. And send it. The receiver 3 is attached to the vehicle body 7 side of the vehicle 1 and receives a transmission frame transmitted from the transmitter 2 and performs various processes and calculations based on the detection signal stored therein. By doing so, the tire pressure is obtained. 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, a transmission antenna 24, and a reception antenna 25.

  The sensing unit 21 includes, for example, a diaphragm type pressure sensor and a temperature sensor, and outputs a detection signal corresponding to the tire pressure and a detection signal corresponding to the temperature.

  The microcomputer 22 is a well-known computer having a control unit (first control unit) 22a, an RF transmission unit 22b, an LF reception unit 22c, and the like, and is a program stored in a memory (not shown) in the control unit 22a. The predetermined processing is executed according to the above.

  The control unit 22a receives the detection signal related to the tire pressure from the sensing unit 21, processes the signal and processes the signal as necessary, and includes data indicating the detection result (hereinafter referred to as tire pressure data) in the transmission frame. After storing, the transmission frame is sent to the RF transmission unit 22b. The process of sending a signal to the RF transmitter 22b is executed at predetermined intervals according to the program.

  The control unit 22a also includes a reception intensity measurement unit 22d that measures the reception intensity of the trigger signal. The reception intensity measurement unit 22d receives from the trigger device 5 received through the reception antenna 25 and the LF reception unit 22c. Measure the reception strength of the trigger signal. Then, the control unit 22a basically processes the measured reception intensity of the trigger signal as necessary, stores the reception intensity data of the trigger signal in a transmission frame in which data related to tire pressure is stored, and then The transmission frame is sent to the RF transmission unit 22b. The process of sending a signal to the RF transmitter 22b is also performed according to the program.

  For example, the transmission timing of how many seconds after receiving the trigger signal to send the transmission frame is set differently for each transmitter 2 in advance. For this reason, transmission frames are transmitted at different timings from the transmitters 2 of the wheels 6a to 6d.

  However, in order to transmit transmission frames at different timings from the transmitters 2 of the wheels 6a to 6d, simply by storing different transmission timings in the control unit 22a of each transmitter 2, The stored contents of the transmitter 2 will be different. For this reason, for example, the control unit 22a provides a map in which the transmission timing can be selected according to the reception strength or a function expression for obtaining the transmission timing using the transmission strength as a variable so that the transmission timing of the transmission frame is shifted according to the reception strength. If the transmission timing of each transmitter 2 is inevitably different due to the difference in reception strength, the program of the control unit 22a of all the transmitters 2 can be made common.

  Moreover, you may set the program memorize | stored in the control part 22a so that transmission timing may be changed at random every time. In this way, if it is changed randomly each time, it is possible to make the transmission timings of the transmitters 2 all different with a high probability.

  The RF transmission unit 22b functions as an output unit that transmits the transmission frame transmitted from the control unit 22a to the receiver 3 through the transmission antenna 24 using an RF band, for example, 315 MHz radio waves. .

  The LF receiving unit 22c functions as an input unit that receives a trigger signal transmitted in the LF band, for example, a radio wave of 125 kHz from the trigger device 5 through the receiving antenna 25 and sends the trigger signal to the control unit 22a.

  The battery 23 supplies power to the control unit 22a and the like, and receives power supply from the battery 23, collects data related to tire pressure in the sensing unit 21, and performs various calculations in the control unit 22a. Is executed.

  The transmitter 2 configured in this way is attached to an air injection valve in each of the wheels 6a to 6d, for example, and is arranged so that the sensing unit 21 is exposed inside the tire. Accordingly, the corresponding tire pressure is detected, and a transmission frame is transmitted at predetermined intervals (for example, every minute) through the transmission antenna 24 provided in each transmitter 2.

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

  The antenna 31 is one or two common antennas that collectively receive transmission frames transmitted from the transmitters 2, and is fixed to the vehicle body 7.

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

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

  The control unit 32b outputs a trigger command signal that instructs the trigger device 5 to output a trigger signal, receives the transmission frame transmitted from the reception unit 32a, and stores each transmitter stored in the transmission frame. Based on the received intensity data of the trigger signal at 2, wheel position detection is performed to identify which transmitted frame is from the transmitter 2 attached to any of the wheels 6a to 6d.

  Further, the control unit 32b obtains the tire air pressure by performing various signal processing and calculation based on the data indicating the detection result stored in the received transmission frame, and displays an electric signal corresponding to the obtained tire air pressure. To the device 4. For example, the control unit 32b compares the obtained tire pressure with a predetermined threshold value Th, and outputs a signal to that effect to the display 4 when detecting that the tire pressure has decreased. Thereby, the indicator 4 is informed that the tire pressure of any of the wheels 6a to 6d has decreased.

  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 a signal indicating that the tire air pressure has decreased is sent from the control unit 32 b in the receiver 3, the display device 4 notifies the driver of the decrease in tire air pressure by displaying that effect.

  When the trigger command signal sent from the control unit 32b of the receiver 3 is input, the trigger device 5 outputs a trigger signal having a predetermined signal strength. The trigger machine 5 is disposed at a position that is different from all four wheels 6a to 6d, and is disposed in the vicinity of the left rear wheel 6d in the present embodiment. For this reason, the distance from the trigger machine 5 to each wheel 6a-6d becomes long in order of the left rear wheel 6d, the right rear wheel 6c, the left front wheel 6b, and the right front wheel 6a in order.

  The trigger machine 5 may be mounted anywhere as long as the surroundings are not covered with metal, but the place where the trigger machine 5 is not covered with metal as much as possible, and stones etc. do not hit during traveling. For example, it is preferably mounted in a liner or a vehicle interior. Moreover, since it is preferable that the trigger machine 5 is disposed at a position where the difference in distance from the trigger machine 5 to each of the wheels 6a to 6d is large, for example, the rear wheels 6c and 6d and the front wheels 6a and 6b It should be placed in front.

  As described above, the tire air pressure detection device to which the wheel position detection device in the present embodiment is applied is configured.

  Next, the operation of the tire pressure detection device configured as described above will be described.

  First, when an ignition switch (not shown) is switched from OFF to ON, the control unit 32b of the receiver 3 is turned on. After a predetermined time has elapsed since the power was turned on, the control unit of the receiver 3 is used for wheel position detection. A trigger command signal is output from 32 b to the trigger machine 5. When this trigger command signal is input to the trigger machine 5, the trigger machine 5 generates a trigger signal having a predetermined signal intensity toward each transmitter 2. When this trigger signal is input to the control unit 22a through the reception antenna 25 and the LF reception unit 22c of each transmitter 2, the control unit 22a enters a wake-up state.

  Then, the control unit 22a performs signal processing on the tire air pressure input from the sensing unit 21 and the detection signal indicating the temperature in the tire as necessary, and stores the signal in the transmission frame as data related to the tire air pressure.

  In addition, the control unit 22a measures the reception intensity of the received trigger signal at the reception intensity measurement unit 22d. The received intensity data representing the measured received intensity of the trigger signal is stored in the transmission frame together with the data related to the tire pressure, and is transmitted to the receiver 3 side through the RF transmitter 22b at every predetermined period.

  Here, it is known that the signal intensity of the trigger signal attenuates according to the distance. For this reason, the closer the distance from the trigger device 5 to the transmitter 2 is, the higher the reception intensity is. As the distance from the trigger device 5 to the transmitter 2 is different, the reception intensity is also different. That is, the reception intensity of the trigger signal when the transmitter 2 receives the signal has a magnitude corresponding to the distance from the trigger device 5 to the transmitter 2.

  In this embodiment, the reception intensity of the trigger signal when received by the transmitter 2 attached to each of the wheels 6a to 6d is, for example, in the range of 50 to 59 for the left rear wheel 6d, and for the right rear wheel 6c. The signal strength of the trigger signal output by the trigger device 5 and the trigger device are within the range of 30 to 39, within the range of 20 to 29 with the left front wheel 6b, and within the range of 10 to 19 with the right front wheel 6a. The distance from 5 to the transmitter 2 is set.

  In the present specification, a wheel that allows the transmitter 2 to receive a trigger signal at a predetermined reception intensity is referred to as a wheel corresponding to the trigger machine. In the present embodiment, since the transmitter 2 can receive the trigger signal at a predetermined reception intensity at all four wheels 6a to 6d, all the four wheels 6a to 6d correspond to the trigger device 5.

  In addition, as described below, when the air pressure detected by the sensing unit 21 is equal to or lower than a predetermined pressure, the control unit 22a of each transmitter 2 uses all the wheels 6a to 6d at regular positions instead of the measured reception intensity data. The reception intensity data selection process is executed for storing the reception intensity data stored in advance in the memory as a value smaller than the reception intensity of the trigger signal received in the transmission frame.

  FIG. 3 shows a flowchart of the reception intensity data selection process. Specifically, pressure detection is performed in step S11 shown in FIG. In this pressure detection, the control unit 22a detects the tire air pressure based on a detection signal input from the sensing unit 21.

  Subsequently, in step S12, it is determined whether or not the tire air pressure detected in step S11 is a predetermined value or less. This determination is to determine whether or not the tire is in a puncture state, and the predetermined value is set to atmospheric pressure or a value slightly higher than the atmospheric pressure so that it is detected that the tire is in a puncture state. Is set.

  If an affirmative determination is made in step S12, it is determined that the tire is in a puncture state, and the process proceeds to step S13, where the received intensity data is stored in advance in a memory (not shown) of the control unit 22a, not the measured received intensity data. For example, reception intensity data of “5” is stored in the transmission frame. Thereafter, this transmission frame is transmitted.

  On the other hand, if a negative determination is made in step S12, it is determined that the tire is not in a puncture state, the process proceeds to step S14, and the measured reception intensity data is stored in the transmission frame as reception intensity data. Thereafter, this transmission frame is transmitted.

  Then, when the transmission frame transmitted from each transmitter 2 is received by the receiver 3, the control unit 32b determines that the transmission frame of the wheels 6a to 6d is received from the received intensity data stored in each transmission frame. It is determined which one is transmitted from the transmitter 2 attached thereto. Specifically, in the control unit 32b, the reception intensity data of each transmitter 2 stored in the transmission frame is read, and each reception intensity is compared with the first to fourth threshold values.

  The first to fourth threshold values are set for each wheel, and are set based on a numerical range that can be taken by the reception intensity when received by the transmitter 2 attached to each wheel. Is. In the present embodiment, since the reception intensity at the left rear wheel 6d is in the range of 50 to 59, the first threshold value for determining the left rear wheel 6d is set to 50. Similarly, since the reception intensity at the right rear wheel 6c is in the range of 30 to 39, the second threshold value for determining the right rear wheel 6c is set to 30, and the reception intensity at the left front wheel 6b is Since it is within the range of 20 to 29, the third threshold value for determining the left front wheel 6b is set to 20, and the reception intensity at the right front wheel 6a is within the range of 10 to 19, so the right front wheel 6a. The fourth threshold value for determining is set to 10.

  As a result, frames whose reception strength is equal to or higher than the first threshold (50 or higher in this example) are transmitted frames from the transmitter 2 attached to the left rear wheel 6d, the reception strength is lower than the first threshold, and second Frames above the threshold (in this example, less than 50 and 30 or more) are transmitted frames from the transmitter 2 attached to the right rear wheel 6c, the received intensity is less than the second threshold, and more than the third threshold (this (In the example, less than 30 and 20 or more) is a transmission frame from the transmitter 2 attached to the left front wheel 6b, and the reception strength is less than the third threshold and the fourth threshold or more (less than 20 and 10 or more) It is determined as a transmission frame from the transmitter 2 attached to the right front wheel 6a.

  At this time, the reception intensity at the transmitter 2 attached to the tire-punctured wheel is set to a value (5 in this example) lower than the fourth threshold value (10 in this example). The transmission frame from the transmitter 2 attached to the vehicle is not discriminated as the transmission frame from the transmitter 2 attached to any of the other wheels 6a to 6d at the regular positions.

  In this way, it is possible to specify from the reception intensity data stored in each transmission frame whether the transmission frame is transmitted from the transmitter 2 attached to any of the wheels 6a to 6d. .

  Further, in the control unit 32b, data indicating the tire air pressure and data indicating the temperature in the tire are extracted from each transmission frame, temperature correction is performed as necessary based on the data indicating the temperature, and the tire air pressure is obtained. Thus, the air pressure of the tire provided in each of the wheels 6a to 6d is obtained.

  When the change in the tire pressure is small such that the difference between the calculated tire pressure and the previously determined tire pressure does not exceed a predetermined threshold, the cycle for detecting the tire pressure remains unchanged (for example, 1 If the change in tire air pressure is large exceeding a predetermined threshold, the cycle is advanced (for example, every 5 seconds).

  Thereafter, if it is determined that the obtained tire pressure is lower than a predetermined threshold value, a signal indicating that is output from the control unit 32b to the display unit 4, and the tire pressure has decreased. It is displayed on the display 4 in a form that can identify any of ˜6d. Thereby, it becomes possible to notify the driver which tire pressure of the wheels 6a to 6d has decreased.

  Finally, when the ignition switch is switched from on to off, a trigger command signal is output from the control unit 32b of the receiver 3 to the trigger unit 5 again, and a trigger signal is output from the trigger unit 5. When this trigger signal is input to the control unit 22a through the reception antenna 25 and the LF reception unit 22c, the transmitter 2 is switched to the Sleep state, and the wheel position detection and tire air pressure detection processing is completed.

  As described above, in the tire air pressure detection device according to the present embodiment, the closer the distance from the trigger machine 5 to each transmitter 2 is, the higher the reception intensity of the trigger signal at each transmitter 2 is. 3 determines which of the wheels 6a to 6d each transmitter 2 is attached to based on the received intensity data stored in the transmission frame from each transmitter received. Specifically, each transmitter 2 is attached to any of the wheels 6a to 6d by determining whether or not the reception intensity data stored in the transmission frame belongs to a numerical range preset for each wheel. To determine whether it is correct.

  Then, as shown in FIG. 3, when the air pressure detected by the sensing unit 21 is equal to or lower than a predetermined pressure, the control unit 22a of each transmitter 2 corresponds to the trigger device 5 instead of the measured reception intensity data, Reception intensity data stored in advance as a value smaller than the reception intensity of the trigger signal received by all the wheels 6a to 6d at the regular positions is stored in the transmission frame.

  For this reason, since the reception intensity transmitted from the transmitter 2 of the punctured wheel is smaller than the reception intensity at the transmitter 2 of all the wheels 6a to 6d at the regular positions, the punctured wheel is not connected to the trunk or the rear seat. Even if it is placed at the same position, the receiving intensity of the trigger signal in the transmitter 2 of the punctured wheel and the transmitter 2 of the other wheel at the normal position is not comparable.

  Therefore, according to the tire air pressure detection device of the present embodiment, it is possible to prevent the reception intensity at the transmitter 2 of the punctured wheel from becoming a factor of erroneous detection of the wheel position, and for each of the other wheels at the normal position. The wheel position to which the transmitter 2 is attached can be accurately determined from the magnitude of the reception intensity of the trigger signal at the transmitter 2.

  In this embodiment, when sending a transmission frame storing data related to tire air pressure from the transmitter 2, the reception intensity data when the trigger signal is received is stored every time in the transmission frame, and from the reception intensity data Although it has been determined whether the transmission frame is sent from the transmitter 2 attached to any of the wheels 6a to 6d, other determination methods may be adopted.

  For example, the ID information is stored in both the transmission frame that stores the reception intensity data of the trigger signal and the transmission frame that stores the data related to the tire pressure, and the wheels 6a to 6d to which the transmitters 2 are attached based on the reception intensity data. ID information is stored when the vehicle is identified, and then the transmission frame storing the data related to the tire pressure based on the ID information is sent from the transmitter 2 attached to any of the wheels 6a to 6d. You may make it discriminate | determine.

(Second Embodiment)
FIG. 4 is a block diagram showing an overall configuration of a tire air pressure detection device to which the wheel position detection device according to the present embodiment is applied. The upper direction in the drawing of FIG. 4 corresponds to the front of the vehicle 1, and the lower direction of the drawing corresponds to the rear of the vehicle 1. The present embodiment is different from the first embodiment in that the trigger machine 5 is the first trigger machine 5a and the second trigger machine 5b, and the following mainly differs from the first embodiment. Will be described.

  As shown in FIG. 4, the trigger machine 5 includes a first trigger machine 5a disposed on the side of the rear wheels 2c 6c, 6d with respect to the front wheels 2a, 6b, and a front wheel 2 with respect to the rear wheels 2c 6c, 6d. It has the 2nd trigger machine 5b arrange | positioned at the wheel | wheel 6a, 6b side, and is comprised. And the 1st trigger machine 5a and the 2nd trigger machine 5b are offset and arrange | positioned in the same direction with respect to the centerline which divides the vehicle 1 symmetrically, and both are four wheels 6a-6d. They are placed at different distances from each other.

  In the present embodiment, the first trigger machine 5a is disposed in the vicinity of the left rear wheel 6d. The reception intensity of the trigger signal from the first trigger device 5a when received by the transmitter 2 attached to each wheel 6a to 6d is within the range of 50 to 59 for the left rear wheel 6d, for example, The rear wheel 6c is in the range of 10-19, and the left front wheel 6b is in the range of 10-19. Moreover, the transmitter 2 of the right front wheel 6a farthest from the first trigger machine 5a does not receive the trigger signal from the first trigger machine 5a. Therefore, the left rear wheel 6d, the left front wheel 6b, and the right rear wheel 6c are wheels corresponding to the first trigger machine 5a. As described above, the signal intensity of the trigger signal output from the first trigger machine 5a and the distance from the first trigger machine 5a to the transmitter 2 are set.

  Similarly, in this embodiment, the 2nd trigger machine 5b is arrange | positioned in the vicinity of the left front wheel 6b. The reception intensity of the trigger signal from the second trigger device 5b when received by the transmitter 2 attached to each wheel 6a to 6d is within the range of 50 to 59 for the left front wheel 6b, for example, and the right front wheel 6a is in the range of 10-19, and the left rear wheel 6d is in the range of 10-19. Note that the transmitter 2 of the right rear wheel 6c farthest from the second trigger machine 5b does not receive the trigger signal from the second trigger machine 5b. Therefore, the left front wheel 6b, the left rear wheel 6d, and the right front wheel 6a are wheels corresponding to the second trigger machine 5b. Thus, the signal strength of the trigger signal output from the second trigger machine 5b and the distance from the second trigger machine 5b to the transmitter 2 are set.

  In this embodiment, the tire pressure detection process is performed after the wheel position detection process is performed using the first and second trigger machines 5a and 5b configured as described above.

  First, in the wheel position detection, a trigger command signal is output from the receiver 3 to one of the first and second trigger machines 5a and 5b, for example, the first trigger machine 5a, and the trigger signal is output from the first trigger machine 5a. Is output.

  Then, in the transmitter 2 that has received this trigger signal, reception intensity data representing the measured reception intensity of the trigger signal is stored in a transmission frame together with ID information for specifying the transmitter, and transmitted to the receiver 3 side. Is done.

  At this time, the control part 22a of each transmitter 2 performs the reception intensity data selection process shown in FIG. 3 similarly to 1st Embodiment. Note that, in step S13 in FIG. 3, the reception intensity data with the reception intensity “5” is stored in the transmission frame, as in the first embodiment. The reception sensitivity of “5” is the first sensitivity that the transmitter 2 receives at each wheel when the left rear wheel 6d, the left front wheel 6b, and the right rear wheel 6c corresponding to the first trigger device 5a are in the normal positions. When the left front wheel 6b, the left rear wheel 6d, and the right front wheel 6a corresponding to the second trigger machine 5b are at regular positions, the value is lower than the reception intensity of the trigger signal from the trigger machine 5a. The value is lower than the reception intensity of the trigger signal from the second trigger device 5b received by the transmitter 2.

  When the transmission frame is received by the receiver 3, the control unit 32b reads the reception intensity data of each transmitter 2 stored in the transmission frame, and each reception intensity is set to the first and second threshold values. To be compared.

  The first and second threshold values are set for each wheel at a position where the trigger signal from the first trigger machine 5a can be received, and are received by the transmitter 2 attached to each wheel. It is set based on a numerical value range that can be taken by the received intensity. In the present embodiment, since the reception intensity at the left rear wheel 6d is in the range of 50 to 59, the first threshold value for determining the left rear wheel 6d is set to 50. Similarly, since the reception intensity at the right rear wheel 6c and the left front wheel 6b is in the range of 10 to 19, the second threshold value for determining the right rear wheel 6c and the left front wheel 6b is set to 10. Yes.

  Thereby, a frame whose reception intensity is equal to or higher than the first threshold (50 or higher in this example) is determined as a transmission frame from the transmitter 2 attached to the left rear wheel 6d. Also, the frames below the first threshold and above the second threshold (in this example, less than 50 and 10 or more) are determined as transmission frames from the transmitter 2 attached to the right rear wheel 6c or the left front wheel 6b. . The transmitter 2 attached to the right rear wheel 6c and the left front wheel 6b is identified using the reception intensity of the trigger signal output from the second trigger machine 5b.

  Subsequently, a trigger command signal is output from the receiver 3 to the other of the first and second trigger devices 5a and 5b, for example, the second trigger device 5b, and a trigger signal is output from the second trigger device 5b.

  As in the case of the output from the first trigger device 5a, the transmitter 2 that has received this trigger signal receives the reception strength data representing the measured reception strength of the trigger signal together with the ID information for identifying the transmitter. It is stored in the transmission frame and transmitted to the receiver 3 side.

  When the transmission frame is received by the receiver 3, the control unit 32b reads the reception intensity data of each transmitter 2 stored in the transmission frame, and each reception intensity is set to the third and fourth threshold values. To be compared.

  The third and fourth threshold values are set for each wheel at a position where the trigger signal from the second trigger machine 5b can be received, and are received by the transmitter 2 attached to each wheel. It is set based on a numerical value range that can be taken by the received intensity. In the present embodiment, since the reception intensity at the left front wheel 6b is within the range of 50 to 59, the third threshold value for determining the left front wheel 6b is set to 50. Similarly, since the reception intensity at the right front wheel 6a and the left rear wheel 6d is in the range of 10 to 19, the fourth threshold value for determining the right front wheel 6a and the left rear wheel 6d is set to 10. Yes.

  As a result, a frame whose reception intensity is greater than or equal to the third threshold (50 or greater in this example) is determined as a transmission frame from the transmitter 2 attached to the left front wheel 6b. Also, the frames below the third threshold and above the fourth threshold (in this example, less than 50 and 10 or more) are determined to be transmission frames from the transmitter 2 attached to the right front wheel 6a or the left rear wheel 6d. .

  Based on these determination results, a transmission frame from the transmitter 2 attached to the right rear wheel 6c and a transmission frame from the transmitter 2 attached to the right front wheel 6a are discriminated.

  This is because the determination result of the wheel position when using the first trigger machine 5a identifies which of the two transmission frames is transmitted from the transmitter 2 attached to the right rear wheel 6c and the left front wheel 6b. Although it was not possible, the transmission frame from the transmitter 2 attached to the left front wheel 6b is specified by the determination result of the wheel position when the second trigger machine 5b is used, so that it is attached to the right rear wheel 6c. The transmitted transmitter 2 can be identified. The same applies to the transmitter 2 attached to the right front wheel 6a.

  The control unit 32b of the receiver 3 discriminates the wheels 6a to 6d to which the transmitters 2 are attached in this way, and then stores the ID information stored in each transmission frame in association with the wheels 6a to 6d. .

  When tire pressure is detected, the control unit 32b of the receiver 3 stores the ID information stored in the transmission frame when the transmission frame storing the tire pressure data is transmitted. Based on the ID information, it is possible to determine which of the wheels 6a to 6d is attached to the transmitter 2 that has transmitted the transmission frame, and to obtain the tire pressure of each of the wheels 6a to 6d. Become.

  As described above, also in the tire air pressure detecting device of the present embodiment, the control unit 22a of each transmitter 2 is measured when the air pressure detected by the sensing unit 21 is equal to or lower than a predetermined pressure, as shown in FIG. Instead of the reception intensity data, it corresponds to each of the first and second trigger machines 5a and 5b and is stored in advance as a value smaller than the reception intensity of the trigger signal received by all the wheels at the normal positions. Reception intensity data is stored in a transmission frame.

  For this reason, since the reception intensity transmitted from the transmitter 2 of the punctured wheel is smaller than the reception intensity at the transmitter 2 of all the wheels 6a to 6d at the regular positions, the punctured wheel is not connected to the trunk or the rear seat. Even if placed in the same manner, the consultation intensity of the trigger signal in the transmitter 2 of the punctured wheel and the transmitter 2 of the other wheel does not become comparable.

  Therefore, according to the tire air pressure detection device of the present embodiment, it is possible to prevent the reception intensity at the transmitter 2 of the punctured wheel from becoming a factor of erroneous detection of the wheel position. The wheel position to which the transmitter 2 is attached can be accurately determined from the magnitude of the reception intensity of the trigger signal at the transmitter 2.

  In the present embodiment, the second trigger machine 5b is disposed in the vicinity of the left front wheel 6b, but may be disposed in the vicinity of the right rear wheel 6c. That is, the first and second trigger machines 5a and 5b can be offset in the same direction with respect to the center line that divides the vehicle body 7 in the longitudinal direction. Even in this case, it is possible to perform the same wheel position detection as in the present embodiment.

  In this embodiment, ID information is stored in a transmission frame transmitted from the transmitter 2 and wheel position detection is performed using this ID information. However, as in the first embodiment, ID information is not used. In addition, wheel position detection may be performed.

(Other embodiments)
In each of the above-described embodiments, the form in which the antenna 31 is one or two common antennas has been described. However, the form may be such that four are provided corresponding to each of the wheels 6a to 6d. . However, when the antenna 31 is a common antenna, it is particularly difficult to specify the wheels 6a to 6d to which the transmitter 2 is attached. Therefore, it is effective to apply the present invention to a shared antenna. .

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Transmitter 3 Receiver 4 Indicator 5 Trigger machine 5a 1st trigger machine 5b 2nd trigger machine 6a Right front wheel 6b Left front wheel 6c Right rear wheel 6d Left rear wheel 21 Sensing part 22 Microcomputer 22a Control part (1st Control part)
22b Transmission unit 22c Reception unit 32 Microcomputer 32a Reception unit 32b Control unit (second control unit)

Claims (5)

Each of a plurality of wheels (6a to 6d) provided with tires is equipped with a receiving unit (22c) that receives a trigger signal, and the reception intensity of the trigger signal received by the receiving unit is measured and measured. Transmission comprising: a first control unit (22a) that stores reception intensity data representing reception intensity in a transmission frame; and a transmission unit (22b) that transmits the transmission frame processed by the first control unit. Machine (2),
A trigger unit (5) that is provided at a location at a different distance from each corresponding wheel on the vehicle body (7) side, and that outputs the trigger signal;
The reception unit (32a) that is provided on the vehicle body side and receives the transmission frame, and the reception intensity represented by the reception intensity data stored in the transmission frame is attached to each wheel from the trigger machine. A receiver (3) having a second control unit (32b) for discriminating which of the plurality of wheels the transmitter is attached from the relationship that the closer the distance to the transmitter is, the larger the distance is; In a wheel position detection device comprising:
The transmitter (2) has a sensing unit (21) for detecting the air pressure of the tire,
When the air pressure detected by the sensing unit is equal to or lower than a predetermined pressure, the first control unit (22a) corresponds to the trigger machine instead of the measured received intensity data, and all the wheels at the normal wheel positions are located. A wheel position detection device, wherein reception intensity data stored in advance as a value smaller than a reception intensity of a trigger signal received by the transmitter attached to the wheel is stored in the transmission frame.   The second control unit (32b) determines whether the reception intensity represented by the reception intensity data stored in the transmission frame belongs to a numerical range set in advance for each wheel. 2. The wheel position detecting device according to claim 1, wherein the wheel (2) determines which of the plurality of wheels is attached. There is only one trigger machine (5),
The second control unit (32b) determines whether or not the reception intensity represented by the reception intensity data stored in the transmission frame belongs to a numerical range preset for each of the plurality of wheels. The wheel position detection device according to claim 1, wherein the transmitter (2) determines which of the plurality of wheels is attached. The plurality of wheels are two front wheels (6a, 6b) and two rear wheels (6c, 6d),
The trigger machine includes a first trigger machine (5a) disposed closer to the two rear wheels than the two front wheels, and a second trigger machine disposed closer to the two front wheels than the two rear wheels. (5b)
The first trigger machine and the second trigger machine are both arranged offset in the same direction with respect to a center line that divides the vehicle body symmetrically,
The second control unit (32b)
Whether the reception intensity represented by the reception intensity data stored in the transmission frame sent from the transmitter belongs to a preset first numerical range when the trigger signal is output from the first trigger machine By determining whether or not the wheel to which the transmitter is attached is a wheel (6d) on the side closer to the first trigger machine among the two rear wheels, and is set in advance. By determining whether or not it belongs to the second numerical range, the wheel to which the transmitter is attached is the wheel (6c) on the side farther from the first trigger device among the two rear wheels and the front wheel 2 It is determined that the wheel is one of the wheels (6b) closer to the first trigger machine,
Whether the reception intensity represented by the reception intensity data stored in the transmission frame sent from the transmitter belongs to a preset third numerical range when the trigger signal is output from the second trigger machine By determining whether or not the wheel to which the transmitter is attached is the wheel (6b) on the side closer to the second trigger machine among the two front wheels, and a preset first By determining whether or not it belongs to the numerical range of 4, the wheel to which the transmitter is attached is the wheel (6a) on the side farther from the second trigger machine among the two front wheels and the two rear wheels. Is determined to be one of the wheels (6d) on the side closer to the second trigger machine,
Based on these discrimination results, the transmitter attached to the wheel (6c) on the side farther from the first trigger machine among the two rear wheels, and the second trigger machine far from the two front wheels. The wheel position detection device according to any one of claims 1 to 3, wherein the transmitter attached to the side wheel (6a) is specified. A tire pressure detecting device comprising the wheel position detecting device according to any one of claims 1 to 4,
The transmitter outputs a detection signal related to the tire air pressure from the sensing unit (21), and the detection signal of the sensing unit is signal-processed by the first control unit and then transmitted via the transmission unit. It is supposed to
In the tire pressure detecting device, the receiver is configured to obtain air pressures of the tires provided to the plurality of wheels based on the detection signals in the second control unit.

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