WO2017018700A1

WO2017018700A1 - Tire pressure monitoring system and method for identifying position of tires

Info

Publication number: WO2017018700A1
Application number: PCT/KR2016/007623
Authority: WO
Inventors: Jae Seong Han; Byoum Youn Cho; Jae Sung So
Original assignee: Seetron Inc.
Priority date: 2015-07-28
Filing date: 2016-07-13
Publication date: 2017-02-02

Abstract

An exemplary embodiment of the present invention provides a tire pressure monitoring system including: a plurality of sensor units mounted in each tire of a commercial vehicle, each to output unique identification information and to include a biaxial sensor that outputs a Z-axis phase and an X-axis phase depending on driving of the commercial vehicle, the biaxial sensors being mounted in opposite directions to output correlation information of the X-axis phase and the Z-axis phase every time point on a setting cycle for a setting time; a wireless receiver configured to receive wireless signals transmitted from the sensor units; and a monitoring unit configured to recognize a position of a tire corresponding to each of the sensor units based on a receipt frequency of the correlation information received from the sensor units every time point on the setting cycle and to recognize whether it is an inner wheel or an outer wheel in dual wheels by using the correlation information.

Description

TIRE PRESSURE MONITORING SYSTEM AND METHOD FOR IDENTIFYING POSITION OF TIRES

The present invention relates to a tire pressure monitoring system and a tire position identifying method, which are applied to a commercial vehicle.

A tire pressure monitoring system (TPMS) mounted in a vehicle is a device in which various sensors are mounted to each tire, senses a pressure of each tire by using tire state information sensed by the sensors, and maintains the pressure of each tire at an appropriate pressure level. The TPMS is required to correspond a tire (or wheel) disposed at a particular position with tire state information received from the sensor to perform such a pressure maintaining function.

Different wheel identification information is given to tire positions, and the tire state information includes corresponding wheel identification information before being sent to recognize a corresponding position.

Meanwhile, when a new tire is replaced, new wheel identification information is generated. Unless a person manually registers the new wheel identification information in the tire state information, the TPMS is not able to recognize the position of the corresponding tire.

To solve such a problem, according to a conventional art, a technique of automatically recognizing the replaced tire after the tire replacement is applied to the TPMS. For example, Korean Patent Laid-Open Publication No. 2012-0128431, (hereinafter referred to as '431 Patent') has disclosed a technique of applying tri-axial geomagnetic sensors, recognizing a steering angle of each tire from the tri-axial geomagnetic sensors, and determining a position of a target tire by using a difference between steering angles of the tires.

Further, Korea Patent Laid-Open Publication No. 2014-0006029 (hereinafter referred to as '029 Patent') has disclosed a technique of using a wheel speed sensor mounted in a vehicle and an acceleration sensor that transmits at a specific position to recognize positions of each tire by comparison and in concert with an acceleration sensor signal in a tire and a phase position of the wheel speed sensor.

However, the '431 Patent and the 029 Patent are mainly applied to passenger cars, and when they are applied to commercial vehicles, it is difficult to recognize which tire is an inner wheel or an outer wheel.

The present invention has been made in an effort to provide a tire pressure monitoring system and a tire position identifying method which can automatically recognize whether a tire that is replaced or switched in a commercial vehicle is a front wheel or a back wheel, or an inner wheel or an outer wheel in a dual wheel setup. The present invention can be used to achieve other effects that are not described in detail in addition to the aforementioned effects.

When the commercial vehicle is moved, the monitoring unit may receive steering angle information, and when the steering angle is equal to or greater than a setting time, may recognize the receipt frequency of the correlation information for each of the sensor units through the wireless receiver for a setting time as a wheel rotational speed of each sensor unit, and a position of a tire corresponding to each of the sensor units by comparing the recognized wheel rotational speed of each of the sensor units with a set wheel rotational speed ratio for each position of a tire.

The monitoring unit may recognize a position of each tire by using the wheel rotational speed ratio for each position of the tires depending on a vehicle type. Each of the sensor units may further include: a pressure sensor configured to sense a tire internal pressure; and a temperature sensor configured to sense a tire internal temperature that is used to compensate a temperature-increasing effect depending on a temperature.

The time point on the setting cycle may be set to one for one tire rotation, which is a point in a Z-axis phase waveform or an X-axis phase waveform of the setting cycle, and the time point on the setting cycle is set to a Zmax point in the Z-axis phase waveform of one cycle or to an Xmax point in the X-axis phase waveform of one cycle.

The monitoring unit may compare the sensor units ID received from the sensor units with a set sensor unit ID for each position of a tire, and when a new sensor unit ID exists, may recognize a position of a tire corresponding to the new sensor unit ID.

When the sensor unit ID received from each of the sensor units coincides with a set sensor unit ID for a position of a tire, the monitoring unit, if a steering angle of a moving vehicle is smaller than a setting angle, may perform tire pressure monitoring by using the set sensor unit ID for the position of the tire, if the steering angle is equal to or greater than the setting angle, may recognize a receipt frequency of each of the sensor units through the wireless receiver for the setting time as a wheel rotational speed of each of the sensor units, may compare the recognized wheel rotational speed of each of the sensor units with a set wheel rotational speed ratio for each position of the tire to recognize a position of a tire of each of the sensor units, and may recognize whether it is an inner wheel or an outer wheel of dual wheels by using the correlation information to recognize a sensor unit ID for each position of the tire.

An exemplary embodiment of the present invention provides a tire position identifying method including: a first step of determining whether a steering angle is equal to or greater than a setting angle during movement of a commercial vehicle; a second step of receiving correlation information of a Z-axis phase and an X-axis phase transmitted every time point on a setting cycle for a setting time from each sensor unit including a biaxial sensor that outputs the Z-axis phase and the X-axis phase depending on driving of the commercial vehicle; a third step of recognizing a position of a tire corresponding to each of the sensor units based on a receipt frequency of the correlation information received from the sensor units every time point on the setting cycle when the steering angle is equal to or greater than the setting angle; a fourth step of recognizing whether it is an inner wheel or an outer wheel of dual wheels depending on whether the Z-axis phase or the X-axis phase precedes through the correlation information of each sensor unit corresponding to the dual wheels when the tire is of the dual wheels; and a fifth step of registering an ID of each of the sensor units to correspond to the position of the tire.

The third step may include recognizing the receipt frequency of the correlation information for each of the sensor units through the wireless receiver for a setting time as a wheel rotational speed of each sensor unit, and a position of a tire corresponding to each of the sensor units by comparing the recognized wheel rotational speed of each of the sensor units with a set wheel rotational speed ratio for each position of a tire.

The tire position identifying method may further include: before the first step, receiving sensor units ID from a plurality of sensor units mounted in each tire of the commercial vehicle; determining whether a new sensor unit ID exists by comparing the received sensor units ID of each of the sensor units with a set sensor unit for each position of a tire; when no new sensor unit ID exists, if the steering angle is smaller than the setting angle, performing tire air pressure monitoring by using the set sensor unit for each position of the tire, and if the steering angle is equal to or greater than the setting angle, sequentially performing the third step to the fifth step.

In the sequentially performing the third step to the fifth step, the fifth step may include determining whether the recognized sensor unit ID for each position of the tire coincides with the set sensor unit ID for each position of the tire, and when the two sensor unit IDs coincide with each other, updating it with the set sensor unit ID for each position of the tire, or directly updating it with the set sensor unit ID for each position of the tire without determining whether the recognized sensor unit ID for each position of the tire coincides with the set sensor unit ID for each position.

According to the exemplary embodiments of the present invention, manufacturing cost is reduced by employing an inexpensive biaxial sensor, an axis to which a tire is mounted and a position of the tire in the axis are recognized by using a rotational speed of each tire in a steering operation, and it is determined whether it is an inner wheel or an outer wheel by using an output of the biaxial sensor, thereby quickly and precisely recognizing a position of the tire.

FIG. 1 is a block diagram illustrating a tire pressure monitoring system according to one exemplary embodiment of the present invention.

FIG. 2 schematically illustrates a tire pressure monitoring system applied to a commercial vehicle according to one exemplary embodiment of the present invention.

FIG. 3 illustrates a biaxial sensor mounted to dual wheels according to one exemplary embodiment of the present invention.

FIG. 4 is a waveform diagram illustrating signals outputted from biaxial sensors of an inner wheel and an outer wheel according to one exemplary embodiment of the present invention.

FIG. 5 illustrates a wheel position identifying method based on a steering angle according to one exemplary embodiment of the present invention.

FIG. 6 is a flowchart illustrating a tire position identifying method in a tire pressure monitoring system according to one exemplary embodiment of the present invention.

FIG. 7 is a flowchart illustrating a tire position identifying method in a tire pressure monitoring system according to another exemplary embodiment of the present invention.

In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, irrelevant portions are omitted to clearly describe the present invention, and like reference numerals designate like elements throughout the specification. Furthermore, detailed descriptions are not given to the well-known arts.

In this specification, unless explicitly described to the contrary, the word "comprise" and variations such as "comprises" or "comprising" will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. In addition, the terms "-er," "-or," and "module" described in the specification mean units for processing at least one function or operation, and can be implemented by hardware components or software components and combinations thereof.

Hereinafter, a tire pressure monitoring system and a tire position identifying method applied to a commercial vehicle according to an exemplary embodiment of the present invention will be described with reference to FIG. 1 to FIG. 6.

FIG. 1 is a block diagram illustrating a tire pressure monitoring system according to one exemplary embodiment of the present invention, and FIG. 2 schematically illustrates a tire pressure monitoring system applied to a commercial vehicle according to one exemplary embodiment of the present invention.

Referring to FIG. 1 and FIG. 2, the tire pressure monitoring system according to the present exemplary embodiment is applied to a commercial vehicle including dual wheels with a plurality of axles, e.g., at least two axles, and includes sensor units 100, a wireless receiver 200, and a monitoring unit 300.

The sensor units 100 are respectively mounted in tires disposed at opposite ends of axles, and unique identification information (sensor unit ID) is given to each of the sensor units 100. Corresponding identification information is included in a wire signal transmitted to the monitoring unit 300.

In detail, each of the sensor units 100 includes a biaxial sensor 110, a pressure sensor 120, a temperature sensor 130, a sensor controller 140, and a wireless receiver 150.

The biaxial sensor 110 serves as an acceleration sensor, and measures and outputs gravitational acceleration of two axes, i.e., Z-axis and X-axis, applied to a rotating tire. The biaxial sensor 110 has a characteristic in which a Z-axis phase and an X-axis phase are reversed according to a mounting direction thereof. Accordingly, the mounting direction of the biaxial sensor 110 is determined depending on a position of the tire. In other words, in the case of dual wheels, the biaxial sensor 110 is mounted in opposite directions to an inner wheel and an outer wheel, respectively. In the case of a single wheel, it is pre-determined whether the mounting direction is set to be the same as the inner wheel or the outer wheel.

The pressure sensor 120 senses and outputs a tire internal pressure, and the temperature sensor 130 senses and outputs a tire internal temperature used to compensate a pressure-increasing effect depending on temperature.

Unique identification information, i.e., a sensor unit ID, is assigned to the sensor controller 140, and a signal including the unique identification information is transmitted through the wireless receiver 150. Further, the sensor controller 140 receives outputs of the biaxial sensor 110, the pressure sensor 120, and the temperature sensor 130, and selectively wirelessly transmits the outputs of each of the sensors from an initial movement of a vehicle based on a setting time. In this case, the sensor controller 140 recognizes an output of the biaxial sensor 110 and provides correlation information of the X-axis phase and the Z-axis phase based on one phase waveform (e.g., Z-axis phase waveform or X-axis phase waveform) to the monitoring unit 300 every time point on a setting cycle in order to recognize a tire rotational speed.

The time point on the setting cycle may be a point Zmax or Zmin of the Z-axis phase waveform, or one point in the phase waveform. Further, the sensor controller 140 may transmit correlation information on each cycle of the phase waveform, or on every two or three cycles thereof. In this case, when using the X-axis phase waveform, the time point on the setting cycle may be a point Xmax or Xmin of the X-axis phase waveform, or one point in the phase waveform, as in the case of using the Z-axis phase waveform.

As will be described below, the time points on the setting cycle provided by the sensor controller 140 are used to recognize the tire rotational speed, and the correlation information is used to recognize whether it is an inner or an outer wheel of the dual wheels.

The wireless receiver 150 is operated depending on the control of the sensor controller 140, and transmits outputs of each of the sensors 110 to 130 by using a wireless signal, i.e., an RF (radio frequency) signal. The wireless receiver 200 receives an RF signal transmitted from the wireless receiver 150.

The monitoring unit 300 recognizes a sensor unit ID corresponding to a position of each tire by using an output of the biaxial sensor 110 of each tire received from the sensor unit 100, identification information (i.e., sensor unit ID) of the sensor unit 100, and steering angle information provided from a vehicle. In this case, the monitoring unit 300 may recognize the sensor unit ID corresponding to the position of each tire by additionally using vehicle type information stored in a storage unit (not illustrated). Herein, the vehicle type information includes information related to a rotational speed ratio of each wheel.

When recognizing the sensor unit ID corresponding to the position of each tire, the monitoring unit 300 recognizes a pressure of each tire by analyzing the outputs of the pressure sensor 120 and the temperature sensor 130 received from the sensor unit 100, and performs a pressure maintaining function corresponding to the recognized pressure.

Hereinafter, a biaxial sensor mounted in dual wheels will be described with reference to FIG. 3 and FIG. 4. FIG. 3 illustrates a biaxial sensor mounted to dual wheels according to one exemplary embodiment of the present invention, and FIG. 4 is a waveform diagram illustrating signals outputted from biaxial sensors of an inner wheel and an outer wheel according to one exemplary embodiment of the present invention.

The biaxial sensor 110 is mounted in each of the outer wheel 10 and the inner wheel 20 of the dual wheels. Hereinafter, the biaxial sensor 110 mounted in the outer wheel 10 is referred to as "a first biaxial sensor 111," and the biaxial sensor 110 mounted in the outer wheel 10 is referred to as "a second biaxial sensor 112."

The first biaxial sensor 111 and second biaxial sensor 112 are mounted in mounting directions that are opposite to each other. As such, when the first and second

biaxial sensors

111 and 112 are mounted in the opposite mounting directions, the Z-axis phases and the X-axis phases of the first and second

biaxial sensors

111 and 112 are different, as shown in FIG. 4. Specifically, as shown in FIG. 4, an X-axis phase S1 preceding a Z-axis phase S2 is sensed in the first biaxial sensor 111, and the Z-axis phase S2 preceding the X-axis phase S1 is sensed in the second biaxial sensor 112.

Alternatively, depending on the mounting directions of the first and second biaxial sensors 111, the Z-axis phase S2 preceding the X-axis phase S1 may be sensed in the first biaxial sensor 111, and the X-axis phase S1 preceding the Z-axis phase S2 may be sensed in the second biaxial sensor 112. Herein, a phase between the Z-axis phase S2 and the X-axis phase S1 is a correlation of the Z-axis phase and the X-axis phase, and the correlation information provided by the sensor controller 140 is related to whether the Z-axis phase S2 precedes the X-axis phase S1 or vice versa.

Meanwhile, it is possible to recognize a rotational speed of each tire (wheel rotational speed) by measuring phase speeds of the phases of the

biaxial sensors

111 and 112 or counting the number of cycles for a setting time. This is because the phase of one cycle of the X-axis and the Z-axis corresponds to one rotation of the tire.

Hereinafter, a wheel position identifying method based on a steering angle will be described with reference to FIG. 5. FIG. 5 illustrates a wheel position identifying method based on a steering angle according to one exemplary embodiment of the present invention.

When a vehicle is turned, rear wheels thereof are always rotated more internally than front wheels positioned on the same axes, and thus the front wheels and the rear wheels move according to different rotational trajectories. Further, a left wheel and a right wheel positioned on the same axis show different rotational trajectories depending on rotational directions thereof. Such a rotational trajectory difference is larger in a commercial vehicle than in a car, and a larger vehicle shows a larger rotational trajectory difference.

For example, referring to FIG. 5, when a steering wheel is rotated right by δ, a left-front wheel 1 and a right-front wheel 2 are rotated right according to the rotation of the steering wheel. In this case, a steering angle α of the left-front wheel 1 is smaller than a steering angle β of the right-front wheel 2, and thus a rotational radius R1 of the left-front wheel 1 is longer than a rotational radius R3 of the right-front wheel.

A left-rear wheel 3 is rotated more internally than the left-front wheel 1, and a right-rear wheel 4 is rotated more internally than the right-front wheel 2. Accordingly, a rotational radius R2 of the left-rear wheel 3 is shorter than the rotational radius R1 of the left-front wheel 1, and a rotational radius R4 of the right-rear wheel 4 is shorter than the rotational radius R3 of the right-front wheel 4. Further, the rotational radius R2 of the left-rear wheel 3 is mostly longer than the rotational radius R3 of the right-front wheel 2.

As such, each wheel of the vehicle has different rotational radiuses R1, R2, R3, and R4, and this characteristic is identically applied to a commercial vehicle. The point that the rotational radiuses R1, R2, R3, and R4 are different when they are rotated around a point O indicates that the rotational speeds of each wheel are different. The wheels are mounted at a constant interval and distance, and thus the rotational speeds of each wheel are different depending on magnitudes of the steering angles, but ratios of the rotational speeds of each wheel according to steering directions are constant.

For example, in the case of a right turn, the left-front wheel 1 shows a highest wheel rotational speed according to lengths of the rotational radius. Next, the left-rear wheel 3, the right-front wheel 2, and the right-rear wheel 4 show lower wheel rotational speeds. In other words, the right-rear wheel 4 shows a lowest wheel rotational speed. For another example, in the case of a left turn, the right-front wheel shows a highest wheel rotational speed. Next, the right-rear wheel 4, the left-front wheel 1, and the left-rear wheel 3 show lower wheel rotational speeds. In other words, the left-rear wheel 3 shows a lowest wheel rotational speed.

Accordingly, when a vehicle is steered, it is possible to recognize positions of each tire by measuring and comparing the rotational speeds of each wheel. Although left, right, front, and rear positions of the tire are recognized by comparing the wheel rotational speed, there is a limit in determination of whether it is an inner wheel or an outer wheel of dual wheels. Accordingly, in the present invention, it is determined whether it is an inner wheel or an outer wheel of dual wheels by using the biaxial sensor 110 in order to precisely recognize a position of the tire.

Hereinafter, a tire position identifying method in a tire pressure monitoring system according to an exemplary embodiment of the present invention will be described with reference to FIG. 6 and FIG. 7.

FIG. 6 is a flowchart illustrating a tire position identifying method in a tire pressure monitoring system according to one exemplary embodiment of the present invention. Referring to FIG. 6, in a state in which a commercial vehicle is stopped, the sensor controller 140 of each sensor unit 100 determines whether the vehicle is moved by using an output of the biaxial sensor 110 or the sensor controller 140 (S601).

When it is determined that the vehicle is not moved through the determining step S601, the sensor controller 140 sets a sleep mode (S602), and transmits a sensor unit ID (identification information) through the wireless receiver 150 on a cycle of a first time (S603). When the vehicle is parked or is not driven, it is not moved. Accordingly, the step S603 may be omitted, but the vehicle condition may be a pusher and tag condition. Thus, in the exemplary embodiment of the present invention, the sensor unit ID is transmitted on the cycle of the first time (e.g., about 10 to 15 min).

When it is determined through the determining step S601 that the vehicle starts to move, the sensor controller 140 transmits sensor unit ID (identification information) and an output of the biaxial sensor 110 on a cycle of a second time for a first time (S604). Herein, the second time is set as a relatively shorter time such as 0.5 or 1 s.

In the case that the vehicle is continuously moved, when a first setting time passes from the time point at which it is determined that that the vehicle starts to move (S605), the sensor controller 140 recognizes an X-axis phase S1 and a Z-axis phase S2 received from the biaxial sensor 110 of each tire for a second time, and transmits correlation information of the X-axis phase S1 and the Z-axis phase S2 (i.e., correlation information related to whether the X-axis phase S1 or the Z-axis phase S2 precedes) at a setting cycle time point (e.g., a time point of Zmax) of the Z-axis phase S2 to the monitoring unit 300, together with the sensor unit ID (S606). In this case, the first setting time is equal to or longer than the first time.

In the case that the vehicle is continuously moved, when a second time is ended or a second setting time passes from the second time (S607), the sensor controller 140 determines that the vehicle is continuously moved and transmits outputs of the pressure sensor 120 and the temperature sensor 130 to the monitoring unit 300 on a cycle of a third time (e.g., 1 or 2 min) (S608).

Meantime, when receiving the sensor unit ID through the wireless receiver 200 to correspond to the step S604 (S610), the monitoring unit 300 compares the sensor unit ID with registered tire sensor units ID (S611).

When the sensor unit ID received in the comparing step S611 coincides with the registered sensor unit ID, the monitoring unit 300 determines there is no tire replacement and performs tire pressure monitoring by using the sensor unit ID for each tire position (S620). In contrast, when the sensor unit ID received in the comparing step S311 does not coincide with at least one of the registered sensor units ID (S612), the monitoring unit 300 recognizes a tire position by using the sensor unit ID received in the step of S606, an output of the biaxial sensor 110, steering angle information, and vehicle type information.

Specifically, the monitoring unit 300 recognizes a current steering angle by receiving steering angle information from a steering angle sensor (not illustrated) included in the vehicle (S613), and determines whether the steering angle is equal to or greater than a setting angle (S614). Herein, when the setting angle is set as a large value, it is possible to obtain a more precise result, but may be set as a minimum angle at which the rotational speed ratios of each wheel are different.

When the steering angle is equal to or greater than the setting angle, the monitoring unit 300 recognizes a steering direction, recognizes a receipt frequency from correlation information of a Zmax point for the second time corresponding to each sensor unit ID received through the step S606 (S615), and recognizes the receipt frequency as a wheel rotational speed of the corresponding sensor unit ID (S616).

The monitoring unit 300 recognizes the wheel rotational speed of each sensor unit ID by using this step (S616), and recognizes a position of a tire corresponding to each sensor unit ID by comparing the wheel rotational speed of the sensor units ID with a rotational speed ratio for each vehicle type and for each tire position (S617).

Then, when two sensor units ID correspond to a same tire position, the monitoring unit 300 determines the tire position as one of dual wheels, and determines whether it is an inner wheel or an outer wheel by using correlation information corresponding to the two sensor units ID and the set correlation information (S618).

Accordingly, the monitoring unit 300 recognizes each sensor unit ID corresponding to all tires by recognizing one sensor unit ID corresponding to a single wheel, and one sensor unit ID corresponding to an inner wheel and one sensor unit ID corresponding to an outer wheel in the case of dual wheels. As such, when the sensor units ID corresponding to all tires are recognized, the monitoring unit 300 registers the recognized sensor units ID to corresponding tire positions (S619).

As such, after the step S619, the monitoring unit 300 can identify tire positions through the sensor units ID included in wireless signals, and when receiving outputs of the pressure sensor 120 and the temperature sensor 130 that are transmitted from each of the sensor units 100 on the cycle of the third time through the wireless receiver 200, recognizes tire positions corresponding to the sensor information, and accordingly monitors a pressure of the corresponding tires (S620).

Hereinafter, a tire position identifying method in a tire pressure monitoring system according to another exemplary embodiment of the present invention will be described with reference to FIG. 7. FIG. 7 is a flowchart illustrating a tire position identifying method in a tire pressure monitoring system according to another exemplary embodiment of the present invention.

Prior to the description, the tire position identifying method described with reference to FIG. 6 may be applied to new tire replacement, but may be difficult to be applied to position switch between previously mounted tires. The tire position identifying method of FIG. 7 may be applied to both the new tire replacement and the tire position switch.

In the present exemplary embodiment, an operation of each sensor unit 100 is the same as the steps S601 to S608, so the description of the operation of the sensor unit 100 will be omitted.

Referring to FIG. 7, when the sensor unit ID transmitted through the operation S604 is received through the wireless receiver 200, the monitoring unit 300 recognizes the received sensor unit ID of each tire (S710), compares the recognized sensor unit ID with a pre-registered sensor unit ID for each tire position (S711), and determines whether the recognized sensor unit ID coincides with the pre-registered sensor unit ID (S712).

When the sensor unit ID received in the determining step S712 does not coincide with the pre-registered sensor unit ID, the monitoring unit 300 performs the step S613 of FIG. 6 and sequentially performs the steps S614 to S620. When the sensor unit ID received in the determining step S712 coincides with the pre-registered sensor unit ID, the monitoring unit 300 recognizes a current steering angle by receiving steering angle information from a steering angle sensor (not illustrated) included in the vehicle (S713), and determines whether the steering angle is equal to or greater than a setting angle.

When the steering angle is smaller than the setting angle, the monitoring unit 300 uses the pre-registered sensor unit ID for each tire position (S715) to perform a tire pressure sensing function by using outputs of the pressure sensor 120 and the temperature sensor 130 received from each of the sensor units 100 (S620).

In contrast, when the steering angle is equal to or greater than the setting angle, the monitoring unit 300 recognizes a steering direction, recognizes a receipt frequency from correlation information of a Zmax point for the second time corresponding to each sensor unit ID provided from the sensor units 100 (S715), and recognizes the receipt frequency as a wheel rotational speed of the corresponding sensor unit ID (S716).

The monitoring unit 300 recognizes the wheel rotational speed of each sensor unit ID by using this step (S716), and recognizes a position of a tire corresponding to each sensor unit ID by comparing the wheel rotational speed of the sensor units ID with a rotational speed ratio for each vehicle type and for each tire position (S717).

Then, when two sensor units ID correspond to a same tire position, the monitoring unit 300 determines the tire position as one of dual wheels, and determines whether it is an inner wheel or an outer wheel by using correlation information corresponding to the two sensor units ID and the set correlation information (S718).

Accordingly, the monitoring unit 300 recognizes each sensor unit ID corresponding to all tires by recognizing one sensor unit ID corresponding to a single wheel, and one sensor unit ID corresponding to an inner wheel and one sensor unit ID corresponding to outer wheel in the case of dual wheels. As such, when the sensor units ID corresponding to all tires are recognized, the monitoring unit 300 compares the pre-registered sensor unit ID for each tire position with the recognized sensor unit ID for each tire position (S720), and determines whether the two sensor units ID coincide with each other (S721).

When the two sensor units ID coincide with each other, the monitoring unit 300 uses the pre-registered sensor unit ID for each tire position as in the step S715 to perform the tire pressure sensing function. In contrast, when the two sensor units ID do not coincide with each other, the monitoring unit 300 determines that positions of tires are switched, and updates the registered sensor units ID with the recognized sensor unit ID for each tire position (S722).

Next, the monitoring unit 300 performs tire air pressure monitoring by using the updated sensor unit ID for each tire position.

Meanwhile, in another exemplary embodiment of the present invention, the step S719 of recognizing the sensor unit ID for each tire position and the step S720 of comparing and determining whether the pre-registered sensor unit ID for each tire position with the recognized sensor unit ID for each tire position are omitted, and the step S722 of updating the registered sensor units ID with the recognized sensor unit ID for each tire position may be performed.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

100: sensor unit 110: biaxial sensor

120: pressure sensor 130: temperature sensor

140: sensor controller 150: wireless receiver

200: wireless receiver 300: monitoring unit

Claims

A tire pressure monitoring system comprising:

a plurality of sensor units mounted in each tire of a commercial vehicle, each to output a unique identification information and to include a biaxial sensor that outputs a Z-axis phase and an X-axis phase depending on driving of the commercial vehicle, the biaxial sensors being mounted in opposite directions to output correlation information of the X-axis phase and the Z-axis phase every time point on a setting cycle for a setting time;

a wireless receiver configured to receive wireless signals transmitted from the sensor units; and

a monitoring unit configured to recognize a position of a tire corresponding to each of the sensor units based on a receipt frequency of the correlation information received from the sensor units every time point on the setting cycle and to recognize whether it is an inner wheel or an outer wheel in dual wheels by using the correlation information.
The tire pressure monitoring system of claim 1, wherein, when the commercial vehicle is moved, the monitoring unit receives steering angle information, and when the steering angle is equal to or greater than a setting time, recognizes the receipt frequency of the correlation information for each of the sensor units through the wireless receiver for a setting time as a wheel rotational speed of each sensor unit, and a position of a tire corresponding to each of the sensor units by comparing the recognized wheel rotational speed of each of the sensor units with a set wheel rotational speed ratio for each position of a tire.
The tire pressure monitoring system of claim 2, wherein the monitoring unit recognizes a position of each tire by using the wheel rotational speed ratio for each position of the tires depending on a vehicle type.
The tire pressure monitoring system of claim 1, wherein each of the sensor units further includes: a pressure sensor configured to sense a tire internal pressure; and a temperature sensor configured to sense a tire internal temperature that is used to compensate a temperature-increasing effect depending on a temperature.
The tire pressure monitoring system of claim 1, wherein the time point on the setting cycle is set to one for one tire rotation, which is a point in a Z-axis phase waveform or an X-axis phase waveform of the setting cycle.
The tire pressure monitoring system of claim 5, wherein the time point on the setting cycle is set to a Zmax point in the Z-axis phase waveform of one cycle or to an Xmax point in the X-axis phase waveform of one cycle.
The tire pressure monitoring system of claim 1, wherein the monitoring unit compares the sensor units ID received from the sensor units with a set sensor unit ID for each position of a tire, and when a new sensor unit ID exists, recognizes a position of a tire corresponding to the new sensor unit ID.
The tire pressure monitoring system of claim 7, wherein, when the sensor unit ID received from each of the sensor units coincides with a set sensor unit ID for a position of a tire, the monitoring unit, if a steering angle of a moving vehicle is smaller than a setting angle, performs tire pressure monitoring by using the set sensor unit ID for the position of the tire, if the steering angle is equal to or greater than the setting angle, recognizes a receipt frequency of each of the sensor units through the wireless receiver for the setting time as a wheel rotational speed of each of the sensor units, compares the recognized wheel rotational speed of each of the sensor units with a set wheel rotational speed ratio for each position of the tire to recognize a position of a tire of each of the sensor units, and recognizes whether it is an inner wheel or an outer wheel of dual wheels by using the correlation information to recognize a sensor unit ID for each position of the tire.
A tire position identifying method comprising:

a first step of determining whether a steering angle is equal to or greater than a setting angle during movement of a commercial vehicle;

a second step of receiving correlation information of a Z-axis phase and an X-axis phase transmitted every time point on a setting cycle for a setting time from each sensor unit including a biaxial sensor that outputs the Z-axis phase and the X-axis phase depending on driving of the commercial vehicle;

a third step of recognizing a position of a tire corresponding to each of the sensor units based on a receipt frequency of the correlation information received from the sensor units every time point on the setting cycle when the steering angle is equal to or greater than the setting angle;

a fourth step of recognizing whether it is an inner wheel or an outer wheel of dual wheels depending on whether the Z-axis phase or the X-axis phase precedes through the correlation information of each sensor unit corresponding to the dual wheels when the tire is of the dual wheels; and

a fifth step of registering an ID of each of the sensor units to correspond to the position of the tire.
The tire position identifying method of claim 9, wherein the third step includes recognizing the receipt frequency of the correlation information for each of the sensor units through the wireless receiver for a setting time as a wheel rotational speed of each sensor unit, and a position of a tire corresponding to each of the sensor units by comparing the recognized wheel rotational speed of each of the sensor units with a set wheel rotational speed ratio for each position of a tire.
The tire position identifying method of claim 9, further comprising:

before the first step,

receiving sensor units ID from a plurality of sensor units mounted in each tire of the commercial vehicle;

determining whether a new sensor unit ID exists by comparing the received sensor units ID of each of the sensor units with a set sensor unit for each position of a tire;

when no new sensor unit ID exists, if the steering angle is smaller than the setting angle, performing tire air pressure monitoring by using the set sensor unit for each position of the tire; and

if the steering angle is equal to or greater than the setting angle, sequentially performing the third step to the fifth step.
The tire position identifying method of claim 11, wherein, in the sequentially performing the third step to the fifth step, the fifth step includes determining whether the recognized sensor unit ID for each position of the tire coincides with the set sensor unit ID for each position of the tire, and when the two sensor unit IDs coincide with each other, updating it with the set sensor unit ID for each position of the tire, or directly updating it with the set sensor unit ID for each position of the tire without determining whether the recognized sensor unit ID for each position of the tire coincides with the set sensor unit ID for each position.
The tire position identifying method of claim 10, wherein the time point on the setting cycle is set to one in one tire rotation, which is a point in a Z-axis phase waveform or an X-axis phase waveform of the setting cycle.