JP2012228895A - Tire air pressure monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire air pressure monitoring device that eliminates the need of mounting an initialization switch and the wiring to the receiver from the initialization switch, while solving the troublesomeness of users in the execution of the initialization compared with a necessary case of operation of the initialization switch.SOLUTION: The tire air pressure monitoring device has a receiver including a control part that obtains the air pressure in the tire based on the detection signal transmitted from the transmitter and operates the alarm when the air pressure of the requested tire falls below the warning threshold. The control part of the receiver is made to use the arbitrary set threshold that can be set to an arbitrary value as a warning threshold. When determined in the steps S12-S16 that the air pressure in the tire has changed from outside the predetermined range into the predetermined range when the vehicle stops, the arbitrary set threshold is calculated based on the air pressure of the tire after the change and the calculated arbitrary setting threshold is memorized.

Description

  The present invention relates to a tire pressure monitoring device.

  As a tire pressure monitoring device, a direct type is known (for example, see Patent Document 1). In this type of tire pressure monitoring 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. Done. The alarm is activated when the detected tire pressure falls below the alarm threshold.

  Further, as such a tire pressure monitoring device, a device that is operated by a user and includes an initialization switch (reset switch) for initializing an alarm threshold is actually mounted on a vehicle. This initialization switch is installed in the passenger compartment and is connected to the receiver by wiring.

  According to this tire pressure monitoring device, for example, when the tire pressure is adjusted to a magnitude different from the recommended pressure, such as when the tire pressure is adjusted to be higher than the recommended pressure, according to the user's preference, the adjustment is performed. An alarm threshold value can be set according to the tire pressure later.

Japanese Patent No. 4175348

  However, the tire pressure monitoring device including the initialization switch has a problem that the user feels troublesome because the user needs to operate the initialization switch in order to initialize the arbitrarily set threshold value. .

  In addition, the tire pressure monitoring device including the initialization switch needs to have an initialization switch and wiring from the initialization switch to the receiver for each vehicle, and the number of components constituting the tire pressure monitoring device increases. In addition, there is a problem that it takes time to install the tire pressure monitoring device on the vehicle.

  In view of the above points, the present invention can eliminate the troublesomeness of the user in performing the initialization compared to the case where the operation of the initialization switch is necessary, and the initialization switch and the initialization switch to the receiver. An object of the present invention is to provide a tire pressure monitoring device that can eliminate the need for wiring on a vehicle.

In order to achieve the above object, in the invention described in claim 1,
The second control unit (32b) uses an arbitrarily set threshold that can be set to an arbitrary numerical value as the alarm threshold.
The transmitter (2) or the receiver (3) uses a predetermined value for identifying whether or not the tire air pressure is lower than the recommended pressure specified for each vehicle. Determination means (S12, S13, S15, S16) for determining whether or not a change from less than a predetermined value to a predetermined value or more
The second control unit (32b) determines whether the tire pressure after the change when the determination means (S12, S13, S15, S16) determines that the tire air pressure has changed from less than a predetermined value to more than a predetermined value when the vehicle is stopped. An arbitrarily set threshold value is calculated with reference to the air pressure of and the calculated arbitrarily set threshold value is stored.

  Here, the adjustment of the tire air pressure is generally performed when the vehicle is stopped, and is performed so that the air pressure is close to the recommended pressure. Therefore, according to the present invention, when the air pressure changes from less than a predetermined value to a predetermined value or more, it is determined that the air pressure has been adjusted and initialization is performed. The threshold value can be automatically initialized without any user operation.

  Therefore, according to the present invention, compared with the case where the operation of the initialization switch is necessary, the troublesomeness of the user in performing the initialization can be eliminated, and the initialization switch and the wiring from the initialization switch to the receiver can be eliminated. Can be eliminated from the vehicle.

In the invention according to claim 2, in the invention according to claim 1,
The predetermined value is set as the first predetermined value, and a predetermined range from the first predetermined value to a second predetermined value higher than the first predetermined value is set,
The determination means (S12, S13, S15, S16) is characterized by determining whether or not the tire air pressure has changed from outside the predetermined range to within the predetermined range when the vehicle is stopped.

  According to this, not only when the tire pressure is lower than the recommended pressure, but also when the air pressure is adjusted so that it is close to the recommended pressure, the air pressure has become higher than the recommended pressure when adjusting the air pressure. In addition, even when readjustment is made from a state higher than the recommended pressure to near the recommended pressure, the optional threshold value can be automatically initialized, and the optional threshold value can be set to an appropriate value. Can be set.

In the invention according to claim 3, in the invention according to claim 1 or 2,
The second control unit (32b) stores an arbitrarily set threshold value for each transmitter (2).
In the second control unit (32b), the transmitter (2) is attached to either the front wheel or the rear wheel among the plurality of wheels (6a to 6d) based on the magnitude relationship of the stored arbitrarily set threshold value. It is characterized by discriminating whether or not it is.

  Here, in a vehicle in which one of the front wheels and the rear wheels is a drive wheel, the tire pressure may be set by the user so that the drive wheel is higher than the non-drive wheel. Therefore, in the tire pressure monitoring device that does not have the wheel position detection function by the trigger machine, it is determined whether the transmitter is attached to the front wheel or the rear wheel from the magnitude relationship of the arbitrarily set threshold value as described above. You can also

  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.

It is a block diagram which shows the whole structure of the tire pressure monitoring apparatus in 1st Embodiment. It is the figure which showed the block configuration of the transmitter and receiver of the tire pressure monitoring apparatus shown in FIG. It is a flowchart which shows the initialization implementation process of the arbitrarily set threshold value which the control part of the receiver of the tire pressure monitoring apparatus shown in FIG. 1 performs.

(First embodiment)
FIG. 1 is a block diagram showing the overall configuration of a tire pressure monitoring apparatus according to the present embodiment. 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 pressure monitoring apparatus is attached to a vehicle 1 and includes a transmitter 2, a receiver 3, a display 4, and a trigger machine 5.

  As shown in FIG. 1, the transmitter 2 is attached to each wheel 6 a to 6 d in the vehicle 1, and detects the air pressure of the tire attached to the wheels 6 a to 6 d and a detection signal indicating the detection result. Is stored in a transmission frame and transmitted. 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. Moreover, the sensing part 21 is provided with the acceleration sensor, and outputs the detection signal according to the acceleration (centrifugal force) which generate | occur | produces by rotation of a wheel.

  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 a detection signal related to the tire pressure or the like from the sensing unit 21, processes the signal and processes it as necessary, and transmits each data as data indicating the detection result (hereinafter referred to as data related to the tire pressure or the like). It is stored in the transmission frame together with the ID information of the machine 2, 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 executed at predetermined intervals according to the program.

  The control unit 22a receives the trigger signal from the trigger device 5 through the reception antenna 25 and the reception unit 22c, and obtains the trigger signal reception intensity by performing signal processing on the trigger signal, and processes the trigger signal as necessary. Is received in a transmission frame in which data relating to tire air pressure is stored, or in a transmission frame different from that, and then the transmission frame is sent to the transmission unit 22b. The process of sending a signal to the transmitter 22b is also performed according to the program.

  Note that the transmission timing of how many seconds after receiving the trigger signal the transmission frame is sent 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.

  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 (not shown) in the control unit 32b. Run.

  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 calculations based on the data indicating the detection result stored in the received transmission frame. And the control part 32b compares the calculated | required tire pressure with a warning threshold value, and when the calculated | required tire pressure falls below a warning threshold value, the signal to that effect is output to the indicator 4. Thereby, the indicator 4 is informed that the tire pressure of any of the wheels 6a to 6d has decreased.

  Here, in the present embodiment, both an arbitrarily set threshold value that can be set to an arbitrary numerical value and a standard threshold value specified by the vehicle manufacturer are used as the alarm threshold value. The standard threshold value is set in advance as a fixed value. On the other hand, the arbitrarily set threshold value is based on the tire pressure obtained from the detection signals transmitted from all the transmitters 2 when the initialization conditions (steps S12, S13, S15, and S16 described later) are satisfied. Is set. Specifically, an air pressure when a predetermined ratio such as 20 to 25% is reduced with respect to the measured tire air pressure is calculated, and the calculated air pressure is stored in the control unit 32b as an arbitrarily set threshold value. Is written and stored in a unit (memory not shown) (initialization of an arbitrarily set threshold value).

  At this time, an arbitrary set threshold value common to each wheel is set based on an average value of tire pressures of all the wheels 6a to 6d, or is arbitrarily set based on each tire pressure for each wheel 6a to 6d. A setting threshold value may be set. Then, the obtained tire pressure is compared with both the arbitrarily set threshold value and the standard threshold value, and when it falls below either, a signal to that effect is output to the display 4.

  The indicator 4 is an alarm device that warns the driver of a decrease in tire air pressure when the tire air pressure decreases. 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 4 displays that fact.

  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.

  As described above, the tire pressure monitoring apparatus according to the present embodiment is configured. Next, the operation of the tire pressure monitoring apparatus configured as described above will be described.

  First, when an unillustrated ignition switch is switched from OFF to ON, wheel position detection is performed. That is, the control unit 32b of the receiver 3 is turned on, and a trigger command signal is sent from the control unit 32b of the receiver 3 to the trigger unit 5 for detecting a wheel position after a predetermined time has elapsed since the power was turned on. Is output. 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 reception unit 22c of each transmitter 2, the control unit 22a enters the Wake-up state and measures the reception intensity of the received trigger signal. When each transmitter 2 obtains the reception intensity of the trigger signal, it stores it in the transmission frame together with the ID information of each transmitter 2 and outputs from the transmitter 2.

  When the transmission frame transmitted from each transmitter 2 is received by the receiver 3, the control unit 32b reads the ID information and the reception intensity data of each transmitter 2 stored in the transmission frame. The ID information is arranged in the order of reception intensity.

  Here, it is known that the signal intensity of the trigger signal attenuates according to the distance. For this reason, since the distance from the trigger machine 5 becomes longer in the order of the left rear wheel 6d, the right rear wheel 6c, the left front wheel 6b, and the right front wheel 6a, the transmitter 2 attached to each wheel 6a to 6d. The reception intensity of the trigger signal when received decreases in the order of the left rear wheel 6d, the right rear wheel 6c, the left front wheel 6b, and the right front wheel 6a.

  Thus, the highest received intensity is the transmission frame from the transmitter 2 attached to the left rear wheel 6d, the second highest is the transmission frame from the transmitter 2 attached to the right rear wheel 6c, the third The lowest frame is determined as the transmission frame from the transmitter 2 attached to the left front wheel 6b, and the lowest frame is determined as the transmission frame from the transmitter 2 attached to the right front wheel 6a. Thereafter, the control unit 32b of the receiver 3 stores the ID information stored in each transmission frame in the memory in association with the wheels 6a to 6d to which the transmitter 2 is attached.

  Next, when the regular transmission mode is set and normal tire pressure detection is performed, as described above, each transmitter 2 indicates the tire pressure from the sensing unit 21 or the temperature in the tire to the control unit 22a. A detection signal is input. The detection signal is signal-processed as necessary to obtain tire pressure data, which is stored in the transmission frame together with the ID information of each transmitter 2 and then transmitted to the receiver 3 through the transmitter 22b every predetermined period. Sent to the side.

  On the other hand, when a transmission frame is transmitted from the transmitter 2, it is received by the antenna 31 of the receiver 3 and input to the control unit 32b through the reception unit 32a. Then, in the control unit 32b, data indicating the tire pressure and data indicating the temperature in the tire are extracted from the transmission frame, temperature correction is performed as necessary based on the data indicating the temperature, and the tire pressure is obtained. At this time, since the ID information is stored in the transmission frame, it is compared with the ID information stored at the time of detecting the wheel position, and the transmission frame is transmitted from the transmitter 2 attached to any of the wheels 6a to 6d. It is determined whether it has been received.

  Then, the calculated tire pressure is compared with both the arbitrarily set threshold value and the standard threshold value, and if it is determined that the tire pressure is lower than either, a signal indicating that is sent from the control unit 32b to the display unit 4. Is output and displayed on the display 4 in a form in which it is possible to identify which of the wheels 6a to 6d the tire air pressure has decreased.

  Next, processing for initializing the arbitrarily set threshold value executed by the control unit 32b will be described. FIG. 3 is a flowchart showing the process of initializing the arbitrarily set threshold value. The initialization process is performed at the same time as the tire air pressure detection process and is repeated at a predetermined cycle. In addition, each step S11-S18 in FIG. 3 is corresponded to the various function implementation | achievement means which the control part 32b has. In particular, steps S12, S13, S15, and S16 correspond to “determination means” recited in the claims.

  In step S11, tire air pressure and acceleration are detected. Here, similar to the tire air pressure detection process, the tire air pressure of each of the plurality of wheels 6a to 6d is based on the tire air pressure data stored in the transmission frame transmitted from each transmitter 2 in the regular transmission mode. Is required. Moreover, the acceleration generated by the rotation of each of the wheels 6a to 6d is obtained based on the data regarding the tire pressure and the data regarding the acceleration stored in the transmission frames transmitted from all the transmitters 2.

  Subsequently, in step S12, it is determined whether or not the vehicle is stopped. Here, based on the acceleration of each wheel 6a-6d calculated | required by step S11, it is determined whether it is a stop state. Specifically, if the vehicle is stopped, the acceleration generated by the rotation of the wheels 6a to 6d is 0, so it is determined whether or not the acceleration is 0. The reason for determining whether or not the vehicle is in a stopped state is that the adjustment of the tire pressure is normally performed in the stopped state.

  Then, if the vehicle is in a running state, a negative determination is made, the tire air pressure is not adjusted, and the initialization execution condition is not satisfied, the flow shown in FIG. 3 ends, and the process returns to the start. On the other hand, if the vehicle is stopped, an affirmative determination is made and the process proceeds to step S13.

  Here, it is determined whether the vehicle is in a stopped state based on the data relating to the acceleration transmitted from all the transmitters 2. However, even if it is determined based on the data relating to the acceleration of three or less transmitters 2. good.

  In step S13, it is determined whether or not the tire air pressure of each of the plurality of wheels 6a to 6d obtained in step S11 is outside a predetermined range. This predetermined range is a range from the first predetermined value to a second predetermined value higher than the first predetermined value, and here, whether the tire air pressure is less than the first predetermined value or higher than the second predetermined value. Is determined.

  The predetermined range is determined based on the recommended tire pressure. The recommended tire pressure is called a specified air pressure (specified air pressure) by a vehicle manufacturer and is specified for each vehicle. The first predetermined value is for determining whether or not the pressure is lower than the recommended pressure, and the second predetermined value is for determining whether or not the tire air pressure is higher than the recommended pressure.

  Specifically, the first and second predetermined values take into account the detection error by the pressure sensor of the sensing unit 21 of the transmitter 2 and the fluctuation factors such as the pressure fluctuation due to the temperature fluctuation with respect to the recommended tire pressure. It is determined. For example, when the recommended pressure of the tire is represented by P1 and the fluctuation range of the air pressure due to temperature variation or the like is represented by α, the predetermined range is from the first predetermined value (P1−α) to the second predetermined value (P1 + α). It becomes the range. As described above, the first and second predetermined values obtained by adding different correction values (positive or negative values) to the recommended tire pressure can be used. As the predetermined range, one previously stored in the memory in the control unit 32b is used, or from the recommended tire pressure P1 and the fluctuation range α of the air pressure stored in advance in the memory in the control unit 32b, the control unit 32b Can be used.

  Here, in this step S13, it is determined whether or not the tire air pressure is outside the predetermined range when the tire air pressure is adjusted when the tire air pressure falls below the recommended pressure and falls below the alarm threshold value. This is because the tire pressure is set to be close to the recommended pressure, and only when the tire pressure needs to be adjusted is to be initialized. Therefore, when the tire air pressures of all the wheels 6a to 6d are within the predetermined range, the tire air pressure is in the vicinity of the recommended pressure, and adjustment of the tire air pressure is unnecessary, so that it is not a target for initialization.

  Further, the case where the tire air pressure is outside the predetermined range includes not only the case where the tire air pressure is lower than the predetermined range but also the case where the tire air pressure is higher than the predetermined range. The case where the tire pressure is higher than the specified range is included, even if the user increases the tire pressure too much when adjusting the tire pressure, it is necessary to readjust the tire pressure by reducing the tire pressure to near the recommended pressure. Because it becomes.

  If the tire pressure of one or more wheels is lower than the predetermined range or higher than the predetermined range, an affirmative determination is made and the process proceeds to step S14, and the tire air pressure of all the wheels 6a to 6d is within the predetermined range. If the result is negative, the flow shown in FIG. 3 ends, and the process returns to the start.

  In step S14, tire pressure and acceleration are newly detected after a predetermined time has elapsed. Here, as in step S11, the tire pressure and acceleration of each of the plurality of wheels 6a to 6d are obtained. Here, the predetermined time is a time required to newly detect the tire air pressure. Note that the tire pressure may be detected only for the wheels for which the tire pressure is determined to be outside the predetermined range in step S13.

  Subsequently, in step S15, as in step S12, it is determined whether or not the vehicle is stopped. Then, if the vehicle is in a running state, a negative determination is made, the tire air pressure is not adjusted, and the initialization execution condition is not satisfied, the flow shown in FIG. 3 ends, and the process returns to the start. On the other hand, if the vehicle is in a stopped state, an affirmative determination is made and the process proceeds to step S16.

  In step S16, it is determined whether or not the tire air pressure is within a predetermined range. Here, it is determined whether or not the newly detected tire pressure has entered the predetermined range at the wheel whose tire pressure is determined to be outside the predetermined range in step S13. For example, it is determined whether or not the newly detected tire air pressure is greater than or equal to a first predetermined value within a predetermined range and less than or equal to a second predetermined value within a predetermined range.

  Then, when the tires of the wheels for which the tire pressure is determined to be outside the predetermined range are filled with air by the user and the tire pressure falls within the predetermined range, an affirmative determination is made and it is determined that the tire pressure is adjusted. Then, the process proceeds to step S17. At this time, when there are a plurality of wheels for which the tire pressure is determined to be outside the predetermined range in step S13, it is preferable to make an affirmative determination when the tire pressure falls within the predetermined range for all of the wheels. In one or more of the above, an affirmative determination may be made when the tire pressure falls within a predetermined range.

  On the other hand, if the newly detected tire pressure remains outside the predetermined range, a negative determination is made, and the process returns to step S14. Thus, in the present embodiment, steps S14 to S16 are repeated until the tire air pressure is adjusted.

  In step S16, it may be determined whether the tire air pressure of all the wheels 6a to 6d is within the predetermined range without specifying the wheel in which the tire air pressure is determined to be outside the predetermined range in step S13.

  In step S17, it is determined whether or not the threshold value when initialized is higher than the standard threshold value. Specifically, an arbitrarily set threshold value is calculated in the same manner as in step S18 described later based on the tire pressure detected in step S14, and it is determined whether or not the calculated threshold value is higher than the standard threshold value. The The judgment is based on whether or not the alarm is activated when the tire pressure drops. The calculated tire pressure is compared with both the optional threshold value and the standard threshold value, and is below either. This is because it is not necessary to initialize the arbitrarily set threshold if the threshold when initialized is equal to or less than the standard threshold.

  If the threshold value when initialized is equal to or less than the standard threshold value, a negative determination is made, the flow shown in FIG. 3 ends, and the process returns to the start. On the other hand, if the threshold value when initialized is higher than the standard threshold value, an affirmative determination is made, and initialization is performed in step S18. As a result, it is possible to prevent an arbitrarily set threshold value from being updated without any benefit, and to suppress the number of memory writes.

  In step S18, the arbitrarily set threshold value is initialized. Specifically, the tire air pressure obtained in step S14, that is, the tire air pressure when the tire air pressure after changing from outside the predetermined range to a value within the predetermined range is used as a reference, and the tire pressure is decreased by a predetermined ratio with respect to the reference. Is calculated, and the calculated tire pressure is written and stored in a memory (not shown) of the control unit 32b as an arbitrarily set threshold value.

  In this way, the arbitrarily set threshold value is initialized.

  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 reception unit 22c, the transmitter 2 is switched to the sleep state, and the wheel position detection, tire air pressure detection, and initialization process are completed.

  According to the present embodiment, the control unit 32b of the receiver 3 determines that the tire air pressure has changed from outside the predetermined range to a value within the predetermined range when the vehicle is stopped, as in steps S12, S13, S15, and S16 in FIG. If the tire pressure is adjusted, the control unit 32b of the receiver 3 initializes the arbitrarily set threshold value. Therefore, the user can set the arbitrarily set threshold after adjusting the tire pressure by the user. The value can be initialized automatically.

Therefore, according to the present embodiment, compared with the case where the operation of the initialization switch is necessary, the troublesomeness of the user in the implementation of the initialization can be eliminated, and the initialization switch and the initialization switch to the receiver can be eliminated. Further, according to the present embodiment, the alarm threshold value (during this test) can be used even when the test procedure is performed according to the TPMS regulatory requirements defined in ECE-R64. Initialization (see (3) and (10) of the following test procedure) can be automatically performed. The test procedure defined by ECE-R64 is the following test procedure. (1) Pressure adjustment to recommended pressure → (2) IG-ON / valve check → (3) Initialization → (4) 20 minutes travel → (5) Air pressure measurement → (6) Pressure value measured by (5) Reduce pressure to -20% → (7) Run for 10 minutes (check lamp lighting) → (8) IG-OFF → ON (check lamp continuation check) → (9) Adjust pressure to recommended pressure → (10) Initialization (Lamp off)
(Second Embodiment)
Although the tire pressure monitoring device of the first embodiment is for detecting the wheel position of the transmitter 2 using the trigger machine 5, the tire pressure monitoring device of the present embodiment is instead of using the trigger machine 5. The wheel position of the transmitter 2 is detected using an arbitrarily set threshold value set for each tire.

  In the present embodiment, the control unit 32b of the receiver 3 executes the initialization threshold value initialization process and the tire pressure detection process as in the first embodiment, except for the wheel position detection process. To do. However, in the process of initializing the arbitrarily set threshold value, the control unit 32b of the receiver 3 stores the arbitrarily set threshold value for each ID information of each transmitter 2.

  In this embodiment, the wheel position of the transmitter 2 is detected as follows.

  In a vehicle in which one of the front wheels and the rear wheels is a drive wheel, the tire pressure may be set by the user so that the drive wheel is higher than the non-drive wheel. In such a case, different arbitrarily set threshold values are received at the front wheels 6a and 6b and the rear wheels 6c and 6d by the process of initializing the arbitrarily set threshold value shown in FIG. 3 described in the first embodiment. It is stored in the memory of the control unit 32b of the machine 3. For this reason, the control unit 32b of the receiver 3 determines that the transmitter 2 has the front wheels 6a and 6b and the rear wheels 6c and 6d among the plurality of wheels 6a to 6d based on the magnitude relationship of the stored arbitrarily set threshold values. It is possible to determine which one is attached.

  Specifically, the control unit 32b of the receiver 3 causes the transmitter 2 in which the higher two arbitrary setting threshold values among the stored four arbitrary setting threshold values are set to drive wheels (for example, , A front wheel in the case of an FF vehicle) and a transmitter 2 in which the lower two arbitrarily set thresholds are set, is not a driving wheel (for example, a rear wheel in the case of an FF vehicle) The ID information of the transmitter 2 and the front and rear wheels are associated with each other and stored in the memory.

  Thus, in the present embodiment, when the tire air pressure is detected and the tire air pressure is below either the arbitrarily set threshold value or the standard threshold value, the tire air pressure is reduced by the front wheels 6a and 6b. It can be displayed on the display 4 in a form in which it can be specified which of the rear wheels 6c and 6d.

  As a result, in the case where the wheel position detection function by the trigger machine is not provided, when the display 4 indicates that the tire pressure has decreased, the user has confirmed the worst four tire pressures, According to the present embodiment, it is only necessary to check the air pressure of one of the front wheels 6a and 6b and the rear wheels 6c and 6d.

(Other embodiments)
(1) In the flowchart shown in FIG. 3, it is determined in step S13 whether or not the tire air pressure is out of a predetermined range (range from the first predetermined value to the second predetermined value). In step S16, the tire air pressure is in the predetermined range. In step S13, it is determined whether or not the tire air pressure is less than a first predetermined value. In step S16, it is determined whether or not the tire air pressure is greater than or equal to a first predetermined value. It may be determined. This is because the adjustment of the tire air pressure is performed so that the tire air pressure is close to the recommended pressure when the tire air pressure is lower than the recommended pressure and lower than the alarm threshold value.

  Even in this case, when the control unit 32b of the receiver 3 determines that the tire air pressure has changed from less than the first predetermined value to more than the first predetermined value when the vehicle is stopped, the tire air pressure is adjusted. Since the control unit 32b of the receiver 3 initializes the arbitrarily set threshold value, the arbitrarily set threshold value can be automatically initialized after the user adjusts the tire pressure.

  By the way, some adjustment devices that adjust the air pressure cannot set the target value of the air pressure. When using such an adjustment device, the air pressure was measured after adjusting the air pressure, and the air pressure reached the target value. It is necessary to confirm. Then, as a result of checking the adjusted air pressure, if the adjusted air pressure becomes too high near the recommended pressure, the user re-adjusts the tire air pressure so that the air pressure is lowered to the recommended pressure.

  In such a case, when the control unit 32b of the receiver 3 determines that the tire air pressure has changed from less than the first predetermined value to more than the first predetermined value when the vehicle is stopped, the tire air pressure is adjusted. When the optional threshold is initialized, the optional threshold is calculated based on the air pressure even if the air pressure after pressure adjustment becomes too high. The problem is that it is too expensive.

  On the other hand, according to the first embodiment, the initialization is automatically performed even when the air pressure is adjusted within a predetermined range from a value higher than the predetermined range. Can do. Therefore, the first embodiment is preferable to the present embodiment.

  By the way, when adjusting the tire pressure, when using a pressure regulator that can set the pressure after adjustment (target value), the tire pressure after pressure adjustment will be around the recommended pressure. Even in this embodiment, the arbitrarily set threshold value can be automatically and appropriately initialized.

  (2) In the first embodiment, the control unit 32b of the receiver 3 makes each determination as to whether or not the initialization implementation conditions such as steps S12, S13, S15, and S16 are satisfied. Apart from this, another control unit (hardware or the like) included in the receiver 3 may be performed, or may be performed by the control unit 22a of the transmitter 2. When the control unit 22a of the transmitter 2 performs, the control unit 22a of the transmitter 2 obtains the tire pressure and acceleration based on the detection signal indicating the tire pressure and the tire acceleration from the sensing unit 21.

  (3) In the first embodiment, whether or not the vehicle is stopped is determined based on the acceleration detected by the sensing unit 21. However, when the control unit 32b of the receiver 3 performs this determination, the in-vehicle LAN is used. It may be performed based on the detection result of the vehicle speed sensor obtained via the vehicle, or may be performed based on the detection result of the gear position sensor obtained via the vehicle-mounted LAN. If the vehicle speed is 0 or the gear position is in the P range, it can be determined that the vehicle is stopped.

  (4) In each of the above-described embodiments, the process of initializing the arbitrarily set threshold value is executed by the control unit 32b of the receiver 3 when the ignition switch is on, but when the ignition switch is off You may make it perform to. In this case, the control unit 32b of the receiver 3 executes an initialization execution process of the arbitrarily set threshold value by power supply from the battery. When the ignition switch is off, it is preferable to limit the communication frequency between the transmitter 2 and the receiver 3 so as to suppress consumption of the battery 23 and the vehicle-mounted battery of the transmitter 2.

1 Vehicle 2 Transmitter 3 Receiver 4 Indicator (Alarm)
5 trigger machine 6a right front wheel 6b left front wheel 6c right rear wheel 6d left rear wheel 7 vehicle body 21 sensing unit 22 microcomputer 22a control unit (first control unit)
22b Transmitter 22c Receiver 23 Battery 24 Transmit antenna 25 Receive antenna 31 Antenna 32 Microcomputer 32a Receiver 32b Control unit (second control unit)

Claims (3)

A sensing unit (21) that is provided in each of a plurality of wheels (6a to 6d) including a tire and outputs a detection signal corresponding to the tire air pressure; and the detection signal of the sensing unit (21) is signal-processed. A transmitter (2) comprising a first controller (22a) and a transmitter (22b) for transmitting the detection signal processed by the first controller (22a);
A receiving unit (32a) provided on the vehicle body (7) side that receives the detection signal, and the tire air pressure is obtained based on the detection signal, and the obtained tire air pressure falls below an alarm threshold value. A tire pressure monitoring device comprising: a receiver (3) including a second control unit (32b) for operating the alarm (4);
The second control unit (32b) uses an arbitrarily set threshold that can be set to an arbitrary numerical value as the alarm threshold.
The transmitter (2) or the receiver (3) uses a predetermined value for identifying whether or not the tire air pressure is lower than the recommended pressure specified for each vehicle when the vehicle is stopped. Determination means (S12, S13, S15, S16) for determining whether or not the tire air pressure has changed from less than the predetermined value to the predetermined value or more;
When the determination means (S12, S13, S15, S16) determines that the tire air pressure has changed from less than the predetermined value to more than the predetermined value, the second control unit (32b) The tire pressure monitoring device, wherein the arbitrarily set threshold value is calculated based on the tire pressure after the change, and the calculated arbitrarily set threshold value is stored. The predetermined value is set as a first predetermined value, and a predetermined range from the first predetermined value to a second predetermined value higher than the first predetermined value is set,
The said determination means (S12, S13, S15, S16) determines whether the air pressure of the tire has changed from outside the predetermined range to within the predetermined range when the vehicle is stopped. Tire pressure monitoring device. The second control unit (32b) is configured to store the arbitrarily set threshold value for each transmitter (2),
The second control unit (32b) is configured so that the transmitter (2) is connected to a front wheel and a rear wheel among the plurality of wheels (6a to 6d) based on the stored magnitude relation of the arbitrarily set threshold value. 3. The tire pressure monitoring apparatus according to claim 1, wherein the tire pressure monitoring apparatus determines which one is attached.

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