Patent Description:
In order to measure inner pressure or temperature of a tire mounted to a vehicle (here, it denotes a tire mounted to a rim wheel), it is known that a sensor including a transmitter of a radio signal (radio wave) is mounted in the tire.

The information detected by the sensor should be managed to correspond with the wheel position (right front wheel, left rear wheel, or the like) of the vehicle to which the tire is mounted. However, the wheel position to which the tire (sensor) is mounted is switched due to a rotation of the tires, and therefore the data relating to the correspondence between an identifier (ID) of the sensor and the wheel position should be updated as needed.

A method that automatically detects the wheel position to which the tire (sensor) is to be mounted, is known in order to avoid such an update to be complicated. For example, a tire pressure monitoring system disclosed in Patent Literature <NUM> has two receivers in a front-rear direction of a vehicle so as to automatically detect a wheel position to which the tire (sensor) is mounted, by using the sensor mounted in the tire to detect a rotation direction of the tire. Attention is also drawn to the disclosures of <CIT> and <CIT>.

However, in the tire pressure monitoring system described above, the sensor that detects the rotation direction is additionally arranged for detecting the wheel position to which the tire (sensor) is mounted. Such an additional sensor leads an increase of cost and a failure rate of the system, and therefore the arranging of the additional sensor should be avoided as much as possible.

Accordingly, an object of the present invention is, in consideration of the problem described above, to provide a tire mount position detection system, a tire mount position detection method, and a tire mount position detection program capable of automatically detecting a wheel position to which a tire (sensor) is mounted, based only on a receiving state of a radio signal transmitted by a transmitter.

One aspect of the present invention are tire mount position detection systems according to claims <NUM> and <NUM>.

Another aspect of the present invention are tire mount position detection methods according to claims <NUM> and <NUM>.

Another aspect of the present invention is a tire mount position detection program according to claim <NUM>.

The same reference signs or similar reference signs are assigned to the same functions or the same components and the description thereof is omitted as needed.

<FIG> is a schematic plane view of a vehicle <NUM> including a tire mount position detection system <NUM>. As shown in <FIG>, the vehicle <NUM> is formed as a car provided with a front axle <NUM> and a rear axle <NUM>. A type of the vehicle is not especially limited, however a large vehicle such as a truck and a mine vehicle having a so-called double tire mounted to the rear axle <NUM> may be mainly considered.

Tires <NUM> to <NUM> are mounted to the vehicle <NUM>. Each of the tires <NUM> to <NUM> is formed as a tire mounted to a rim wheel (it may be called a tire wheel assembly).

Here, the tire <NUM> is mounted to a position of a left front wheel (position <NUM> in the figure, the same hereinafter). Similarly, the tires <NUM> to <NUM> are mounted to positions of a right front wheel <NUM>, a left rear outer wheel <NUM>, a left rear inner wheel <NUM>, a right rear inner wheel <NUM>, and a right rear outer wheel <NUM>, respectively.

A sensor <NUM> that measures inner pressure and temperature of the tire <NUM> is mounted to the tire <NUM>. The sensor <NUM> may include a sensor that measures acceleration. The sensor <NUM> includes a transmitter that transmits data of the measured inner pressure and temperature. Similarly, sensors <NUM> to <NUM> are mounted to the tires <NUM> to <NUM>, respectively. Each of the sensors <NUM> to <NUM> can be suitably used for a tire pressure monitoring system (TPMS) or the like.

An identifier "a" that identifies the sensor <NUM> (transmitter) is assigned to the sensor <NUM> as a sensor ID. Similarly, identifiers "b" to "f" are assigned to the sensors <NUM> to <NUM>, respectively as sensor IDs.

The tire mount position detection system <NUM> detects that each of the tires <NUM> to <NUM> to which the sensors (transmitters) <NUM> to <NUM> are mounted, is mounted to which wheel position (positions <NUM> to <NUM> in the figure) of the vehicle <NUM>.

The tire mount position detection system <NUM> includes a receiver unit <NUM> and a position detection device <NUM>. The receiver unit <NUM> is arranged in the vehicle <NUM> so as to receive the radio signals (radio wave) transmitted by the sensors <NUM> to <NUM> (transmitters).

In the present embodiment, the receiver unit <NUM> is formed by a receiver <NUM> and a receiver <NUM>. In the present embodiment, the receiver <NUM> is served as a first receiver. Further, the receiver <NUM> is served as a second receiver.

The receiver <NUM> is described as "R1" as needed, for convenience of description. The receiver <NUM> receives the radio signals transmitted by the sensors (transmitters), namely the sensors <NUM> to <NUM>. Here, intensity (transmission power) and a frequency band of the radio signal may be different depending on a use area of the tire mount position detection system <NUM> or a type of the vehicle <NUM>.

The receiver <NUM> is described as "R2" as needed, for convenience of description. The receiver <NUM> also receives the radio signals transmitted by the sensors <NUM> to <NUM>. The receiver <NUM> is arranged at a position different from that of the receiver <NUM>.

In the present embodiment, the receiver <NUM> is arranged at one side with respect to a center line CL between the left wheel (for example, position <NUM>) and a right wheel (for example, position <NUM>). The receiver <NUM> is arranged at another side with respect to the center line CL.

In the present embodiment, the receiver <NUM> is arranged at a position whose distances from respective axles of the vehicle <NUM>, specifically distances from the front axle <NUM> and the rear axle <NUM>, are different to each other. That is, it is preferable that the receiver <NUM> is not arranged at a position whose distances from the front axle <NUM> and the rear axle <NUM> are identical to each other. Similarly, the receiver <NUM> is also arranged at a position whose distances from the front axle <NUM> and the rear axle <NUM> are different to each other.

The position detection device <NUM> detects the wheel positions (positions <NUM> to <NUM>) to which the tires <NUM> to <NUM>, namely the sensors <NUM> to <NUM> are mounted, by using the receiver unit <NUM>. In the present embodiment, the position detection device <NUM> is installed as a part of an electronic control unit (ECU) mounted to the vehicle <NUM>. Here, as described below, a function achieved by the position detection device <NUM> may be arranged at an outside (crowd server or the like) of the vehicle <NUM>, connected via a communication network.

Next, a functional block configuration of the tire mount position detection system <NUM> will be described. Specifically, a functional block configuration of the position detection device <NUM> forming the tire mount position detection system <NUM> is described.

<FIG> is the functional block diagram of the position detection device <NUM>. As shown in <FIG>, the position detection device <NUM> is provided with a first measurement portion <NUM>, a second measurement portion <NUM>, a signal intensity calculation portion <NUM>, a region determination portion <NUM>, and a position detection portion <NUM>.

The position detection device <NUM> includes hardware such as a CPU and a memory, and the functional portions described above can be achieved by executing a computer program (software) on the hardware.

The first measurement portion <NUM> is connected to the receiver <NUM>. The first measurement portion <NUM> measures the intensity (first signal intensity) of the radio signals received by the receiver <NUM>, for each of the sensors (transmitters) <NUM> to <NUM>.

The second measurement portion <NUM> is connected to the receiver <NUM>. The second measurement portion <NUM> measures the intensity (second signal intensity) of the radio signals received by the receiver <NUM>, for each of the sensors (transmitters) <NUM> to <NUM>.

Hereinafter, a signal, which is transmitted from the sensor <NUM> (sensor ID: a), received by the receiver <NUM> (first receiver) is described as R1(a). Similarly a signal, which is transmitted from the sensor <NUM> (sensor ID: a), received by the receiver <NUM> (second receiver) is described as R2(a) (the same shall be applied to other sensors).

The intensity of the radio signal which is a measurement target of the first measurement portion <NUM> and the second measurement portion <NUM> may be a voltage level or a power level. Or alternatively, the intensity of the radio signal may be a value with a unit of decibel (dB). In the present embodiment, the voltage level (unit of V) is adopted.

Further, in the present embodiment, each of the radio signals transmitted by the sensors <NUM> to <NUM> includes the sensor ID (identifier) that identifies each sensor (transmitter).

The signal intensity calculation portion <NUM> executes a calculation using the intensity of the radio signals measured by the first measurement portion <NUM> and the second measurement portion <NUM>.

Specifically, the signal intensity calculation portion <NUM> calculates a total value (sum) of the intensity (first signal intensity) of the radio signal received by the receiver <NUM> and the intensity (second signal intensity) of the radio signal received by the receiver <NUM>, for each sensor. In the present embodiment, the signal intensity calculation portion <NUM> is served as a calculation portion.

More specifically, the signal intensity calculation portion <NUM> calculates the total value (R1 + R2) of the signal intensity described below.

<FIG> is a graph illustrating an example of the total values (R1 + R2) of measured intensity of the radio signals. The signal intensity calculation portion <NUM> calculates the total value (R1 + R2) shown in <FIG>, for each sensor. The content of <FIG> is further described below.

The region determination portion <NUM> determines that each sensor is located in which region in the vehicle <NUM>, based on a magnitude relation between the total values (R1 + R2) of the signal intensity calculated by the signal intensity calculation portion <NUM>. That is, the region determination portion <NUM> specifies an approximate position of each sensor in the vehicle <NUM>, based on the magnitude relation between the total values.

Specifically, the region determination portion <NUM> determines that each sensor (transmitter) is located in which region in a front-rear direction and a left-right direction of the vehicle <NUM>. That is, the region determination portion <NUM> determines that each sensor is located in which region in a plane view of the vehicle <NUM> shown in <FIG>.

<FIG> is a view illustrating the region for determining the position of the sensor in the vehicle <NUM>. As shown in <FIG>, a region α, a region β, and a region γ are formed in the vehicle <NUM>. The region α includes the wheel positions <NUM> and <NUM> (left front wheel and right front wheel). The region β includes the wheel positions <NUM> and <NUM> (left rear inner wheel and right rear inner wheel). The region γ is a region other than the region α and the region β, namely the region γ includes the wheel positions <NUM> and <NUM>, (left rear outer wheel and right rear outer wheel).

The region determination portion <NUM> determines that which sensor is located in which region, based on the magnitude relation between the total values (R1 + R2) shown in <FIG>. As shown in <FIG>, it is determined that the sensors having the sensor IDs a and b (sensors <NUM> and <NUM>), which have large total values, are located in the region α. That is, it is based on a premise that the receiver unit <NUM> (receiver <NUM> and receiver <NUM>) is arranged closer to the front axle <NUM> and the intensity of the radio signals transmitted from the wheel positions <NUM> and <NUM> (left front wheel and right front wheel) is larger than the intensity of the radio signals transmitted from other wheel positions.

Further, it is determined that the sensors having the sensor IDs d and e (sensors <NUM> and <NUM>), which have the total values the second largest to the total values of the sensors having the sensor IDs a and b, are located in the region β. As described above, it is based on a premise that the receiver unit <NUM> is arranged closer to the front axle <NUM> and the intensity of the radio signals transmitted from the wheel positions <NUM> and <NUM> is smaller than the intensity of the radio signals transmitted from the wheel positions <NUM> and <NUM> and is larger than the intensity of the radio signals transmitted from the wheel positions <NUM> and <NUM>. As a result, it is determined that the sensors having the sensor IDs c and f (sensors <NUM> and <NUM>) are located in the region γ.

The position detection portion <NUM> detects the wheel position of the tire to which the sensor (transmitter) is mounted. Specifically, the position detection portion <NUM> detects each of the wheel positions of the tires <NUM> to <NUM> to which the sensors <NUM> to <NUM> are mounted respectively.

The position detection portion <NUM> detects the wheel position of the tire to which the sensor is mounted, based on the intensity (first signal intensity) of the radio signal received by the receiver <NUM>, the intensity (second signal intensity) of the radio signal received by the receiver <NUM>, and the total value (R1 + R2) described above. Specifically, the position detection portion <NUM> detects the wheel position of the tire to which the sensor is mounted, based on the first signal intensity, the second signal intensity and the total value of each sensor.

More specifically, the position detection portion <NUM> detects that the sensor is mounted to which wheel position within the region (regions α, β, or γ) that the sensor is located determined by the region determination portion <NUM> based on the total value (R1 + R2).

For example, the position detection portion <NUM> detects that the tire <NUM> to which the sensor <NUM> (sensor ID: a) is mounted, is mounted to the wheel position <NUM> within the region (region α), based on the magnitude relation between the first signal intensity (R1(a)) and the second signal intensity (R2(a)). The position detection portion <NUM> detects that other sensor (tire) is mounted to which wheel position, by means of a similar procedure. A more specific detection method of the wheel position is described below in detail.

Further, the position detection portion <NUM> is formed to be able to precisely detect the wheel position to which the sensor (tire) is mounted, even in a case in which the receiver <NUM> or the receiver <NUM> does not work normally due to its failure or the like.

Specifically, in a case in which the magnitude relation between the first signal intensity (R1(a)) and the second signal intensity (R2(a)) of the radio signal transmitted by the sensor <NUM> (first transmitter) mounted to a predetermined wheel position (for example, position <NUM>) is similar to the magnitude relation between the first signal intensity (R1(b)) and the second signal intensity (R2(b)) of the radio signal transmitted by the sensor <NUM> (second transmitter) mounted to a wheel position (for example, position <NUM>) opposite to the predetermined wheel position in the left-right direction or the front-rear direction of the vehicle, the position detection portion <NUM> detects the wheel position to which the sensor is mounted, based on a difference between the first signal intensity and the second signal intensity.

Hereinafter, a case in which the receiver <NUM> can normally receive a radio signal, while the receiver <NUM> cannot normally receive a radio signal because the sensitivity of the receiver <NUM> is deteriorated or the intensity of the radio signal is decreased due to the deterioration of the transmission environment of the radio signal, will be described.

When the receiver <NUM> and the receiver <NUM> can normally receive the radio signal, R1(a) > R2(a) is fulfilled with respect to the radio signal transmitted by the sensor <NUM> (sensor ID: a) because of their positional relation (in a case of no difference in the path loss between the sensor and the receiver). While, R1(b) < R2(b) is fulfilled with respect to the radio signal transmitted by the sensor <NUM> (sensor ID: b) because of their positional relation.

However, when the intensity of the radio signal received by the receiver <NUM> is largely decreased due to the failure described above, a case in which R1(a) > R2(a) and R1(b) > R2(b) are fulfilled might occur. The detection in such a case will be described in accordance with the example described above. That is, the position detection portion <NUM> detects the wheel positions to which the tire having the sensor <NUM> (first transmitter) and the tire having the sensor <NUM> (second transmitter) are mounted, by using the signal intensity of the transmitter in which the difference between the first signal intensity (R1(a), R1(b)) and the second signal intensity (R2(a), R2(b)) among the receiver <NUM> and the receiver <NUM> is larger.

Specifically, the position detection portion <NUM> calculates R1(a) - R2(a) and R1(b) - R2(b), and then the position detection portion <NUM> detects the wheel position to which the sensor is mounted, by using the signal intensity of the transmitter (sensor ID: a or b) in which the difference is larger. A more specific example will be described below.

Next, operation of the tire mount position detection system <NUM> described above will be described. Specifically, an initial setting operation, a tire (sensor) position detection operation, and an operation in a measurement failure of the tire mount position detection system <NUM> will be described.

<FIG> is a flow chart illustrating a flow of the initial setting operation of the tire mount position detection system <NUM>. As shown in <FIG>, firstly, a basic configuration of the vehicle <NUM> to which the tire mount position detection system <NUM> is mounted is set. Specifically, an axle configuration of the vehicle <NUM> is set (S10). The axle configuration includes information relating to the number of axles of the vehicle <NUM>, the presence or absence of a double tire, the number of the tires, and the like.

Secondly, an initial setting of the regions α, β, and γ, which correspond to the number of the receivers and the positions of the receivers arranged in the vehicle <NUM>, shown in <FIG> is executed based the received signal intensity of the radio signal transmitted from each wheel position (S20).

Specifically, the signal intensity corresponding to the regions α, β, and γ is set based the received signal intensity of the radio signal transmitted from each wheel position. In particular, the signal intensity is largely changed depending on a body structure of the vehicle <NUM>, and a type, a size and a position of a component (for example, fuel tank) to be mounted. Thus, the signal intensity, which is standard in each region, is adjusted based on such a transmission environment.

The initial setting of the signal intensity described above is repeatedly executed for each wheel, and thereafter the setting operation is ended (S30).

<FIG> is a flow chart illustrating a flow of the tire (sensor) position detection operation of the tire mount position detection system <NUM>. As shown in <FIG>, the tire mount position detection system <NUM> acquires the signal intensity of the radio signal, which is transmitted by each sensor, received by the receiver R1 and the receiver R2 (S110).

The tire mount position detection system <NUM> calculates the total value of the signal intensity of the radio signal received by the receiver R1 and the signal intensity of the radio signal received by the receiver R2, for each sensor (S120). Here, the total value is described as R1(x) + R2 (x) (x denotes the sensor ID). The tire mount position detection system <NUM> repeats the calculation of the total value for each wheel (S130).

In this way, the tire mount position detection system <NUM> uses two characteristics of the received signal intensity of the receivers R1 and R2 in order to detect the position of the tire (specifically, the position of the sensor in the tire). Firstly, the tire mount position detection system <NUM> determines an approximate position of the sensors <NUM> to <NUM> (sensor IDs: a to f) by using the first characteristic.

Since the received intensity of the radio signal (radio wave) is smaller as being far away from a transmission source, for example, the value of R1(a) denotes "proximity between the sensor <NUM> (sensor ID: a) and the receiver R1". Further, since the receiver R1 and the receiver R2 are arranged to be aligned at a front center part of the vehicle <NUM>, R1(a) + R2(a) denotes "proximity between the sensor <NUM> (sensor ID: a) and the front center part of the vehicle <NUM>".

As shown in <FIG>, the value of R1(x) + R2 (x) (total value), which is "the sum of the received intensity", is classified into three groups. Based on the configuration that the sensors <NUM> to <NUM> (sensor IDs: a to f) are installed (mounted) to the tires <NUM> to <NUM>, the three groups correspond to three regions α, β, and γ depending on the distances from the receivers R1 and R2 (see <FIG>). This is the first characteristic.

The tire mount position detection system <NUM> determines that each sensor is located in which region α, β, or γ, based on the calculation result of the total value (S <NUM>).

As shown in <FIG>, the tire mount position detection system <NUM> determines that the sensor <NUM> (sensor ID: a, total value: <NUM> V) and the sensor <NUM> (sensor ID: b, total value: <NUM> V) of the group having the largest total value are located in the region α.

Next, the tire mount position detection system <NUM> determines that the sensor <NUM> (sensor ID: d, total value: <NUM> V) and the sensor <NUM> (sensor ID: e, total value: <NUM> V) of the group having the second largest total value are located in the region β.

Further, the tire mount position detection system <NUM> determines that the sensor <NUM> (sensor ID: c, total value: <NUM> V) and the sensor <NUM> (sensor ID: f, total value: <NUM> V) of the group having a small total value are located in the region γ.

The tire mount position detection system <NUM> detects the wheel position (positions <NUM> to <NUM>) to which the sensor (tire) is mounted, for each sensor (S150).

Specifically, the tire mount position detection system <NUM> detects that the sensor is mounted to which wheel position within each region (region α, β, or γ) shown in <FIG>. For example, as shown in <FIG>, regarding the sensor <NUM> (sensor ID: a), when R1(a) and R2(a) are compared, R1(a) > R2(a) is fulfilled in region α. On the other hand, regarding the sensor <NUM> (sensor ID: b), R1(b) < R2(b) is fulfilled in the region α.

This denotes that "the sensor <NUM> (sensor ID: a) is closer to the receiver R1 than the receiver R2, and the sensor <NUM> (sensor ID: b) is closer to the receiver R2 than the receiver R1". In this way, the difference between the relative distances to the receiver R1 and the receiver R2 is associated with the received intensity. This is the second characteristic. That is, the tire mount position detection system <NUM> can detect, namely identify the wheel position to which each of two sensors, which are determined to be located in the same region in Step S140, is mounted, by comparing the received intensity of the receiver R1 and the received intensity of the receive R2.

As described above, a case in which the receiver R1 or the receiver R2 cannot exhibit its predetermined performance due to the failure might occur. For example, it is likely that receiving performance of one of the receivers is deteriorated due to an error relating to a mount position or a mount angle of the receiver.

Hereinafter, an example case in which the receiving performance of the receiver R2 is deteriorated compared to that of the receiver R1 is described. That is, it is a case in which the measurement value of the receiver R2 is smaller than the measurement value of the receiver R1 although the distances from a specific sensor are identical.

Further, the processes until Step S140 shown in <FIG> are finished, and the sensor <NUM> (sensor ID: a) and the sensor <NUM> (sensor ID: b) are determined to be located in the region α.

R1(a) is represented by the product of intensity (a) of the radio signal (radio wave) transmitted by the sensor <NUM> (sensor ID: a), an amount (Ln) attenuated until the radio signal arrives at the receiver, and a receiving rate (E1) of the receiver R1. Each of R1(a), R2(a), R1(b), and R2(b) is represented as below.

Since each of the mount positions of the sensors and the wheel positions are symmetry, the attenuation term (L) due to the distance is represented as (Ln) in a case in which the receiver is close to the sensor, or (Lf) in a case in which the receiver is far from the sensor. Further, the receiving rate E1 (E2) denotes a rate of the available radio signal received by the receiver R1 (R2) among the radio signal that arrives at the receiver R1 (R2). In a case in which a half of the radio signal is available among the radio signal transmitted at the predetermined intensity, the receiving rate is <NUM>.

Even if the receiving performance of the receiver R2 is slightly low, there is no problem to determine the wheel position to which the sensor (tire) is mounted, as long as R1(a) > R2(a) and R1(b) < R2(b) are fulfilled. However, it is considered that, when the received intensity of the receiver R2 is low enough, R1(b) > R2(b) might be fulfilled.

It is a case in which the receiver R1, which is far away from the sensor <NUM> (sensor ID: b), receives a signal stronger than the receiver R2, which is close to the sensor <NUM> (sensor ID: b), because the receiving performance of the receiver R2 is deteriorated. In other words, "the magnitude relation of the received intensity of the sensor <NUM> (sensor ID: b), which is not normal and is close to the receiver, is inverted.

In this case, according to the detection logic described above, both of the sensor <NUM> (sensor ID: a) and the sensor <NUM> (sensor ID: b) are close to the receiver R1, and therefore the wheel position cannot be detected precisely. In order to solve such a problem, it is necessary to determine which inequality is correct among R1(a) > R2(a) and R1(b) > R2(b). In other words, "it is necessary to correctly determine which sensor among the sensor <NUM> (sensor ID: a) and the sensor <NUM> (sensor ID: b) is located at a side of the normal receiver.

Thus, the tire mount position detection system <NUM> compares the magnitude of R1(a) - R2(a) and the magnitude of R1(b) - R2(b) in the following way for the determination described above.

As obvious from this, the difference of the received intensity of the sensor <NUM> (sensor ID: a) is always large. Since the sensor <NUM> (sensor ID: a) is close to the normal receiver R1, it is proved that "the sensor having the larger difference of the received intensity is close to the normal receiver".

Thus, in a case in which R1(a) > R2(a) and R1(b) > R2(b), or R1(a) < R2(a) and R1(b) < R2(b) are fulfilled, the wheel position to which the sensor is mounted can be determined by using only the data of the sensor having the larger difference of the received intensity.

According to the embodiment described above, the following functions and effects are obtained. Specifically, according to the tire mount position detection system <NUM>, the wheel position to which the tire having the sensor is mounted is detected, based on the first signal intensity (for example, R1(a)), which is the intensity of the radio signal transmitted from the sensor (transmitter) and received by the receiver <NUM>, the second signal intensity (for example, R2(a)), which is the intensity of the radio signal transmitted from the sensor (transmitter) and received by the receiver <NUM>, and the total value (R1(a) + R2(a)) of the first signal intensity and the second signal intensity.

More specifically, it is determined that the sensor (transmitter) is located in which region α, β, or γ based on the magnitude relation of the total values, and then it is detected that the tire having the sensor (transmitter) is mounted to which wheel position within the determined region, based on the magnitude relation between the first signal intensity and the second signal intensity.

With this, the wheel position to which the tire (sensor) is mounted can be detected automatically, based only on a receiving state of the radio signal transmitted by the sensor. That is, a sensor that detects a rotation direction of the tire is not needed for detecting the wheel position to which each tire is mounted. With this, an increase of the cost and an increase of the failure rate of the system can be avoided.

That is, according to the tire mount position detection system <NUM>, even if the tire to which the sensor is mounted is switched due to a tire rotation, the wheel position to which the tire (sensor) is mounted can be detected automatically. Furthermore, the wheel position to which the tire (sensor) is mounted can be detected automatically, based only on the receiving state of the radio signal transmitted by the sensor.

According to the present embodiment, the receiver <NUM> is arranged at one side (left side) with respect to the center line CL between the left wheel and the right wheel, and the receiver <NUM> is arranged at another side (right side) with respect to the center line CL. Further, each of the receiver <NUM> and the receiver <NUM> is arranged at the position whose distances from respective axles of the vehicle <NUM> are different to each other. With this, the intensity of the radio signal transmitted by each sensor is apt to be different, and this configuration facilitates the initial setting (see <FIG>) of the tire mount position detection system <NUM>.

In the present embodiment, even in a case in which R1(a) > R2(a) and R1(b) > R2(b) are fulfilled due to the failure of the receiver <NUM>, the wheel position can be detected by using the signal intensity of the transmitter in which the difference between the first signal intensity (R1(a), R1(b)) and the second signal intensity (R2(a), R2(b)) is larger. With this, even in a case in which the receiving performance of one receiver is deteriorated, the wheel position to which the tire (sensor) is mounted can be detected precisely.

In the present embodiment, the radio signal transmitted by the sensor (transmitter) includes the identifier (sensor ID) that identifies the sensor (transmitter). With this, the tire mount position detection system <NUM> can identify the sensor transmitting the radio signal easily.

Next, other embodiment of the tire mount position detection system will be described. The vehicle <NUM> including the tire mount position detection system <NUM>, and the functional block configuration of the tire mount position detection system <NUM> are similar to those shown in <FIG>.

Hereinafter, a functional block of the tire mount position detection system <NUM> according to the present embodiment is described. The description of the functional block similar to that in the first embodiment is omitted.

A signal intensity calculation portion <NUM> according to the present embodiment also executes a calculation using the intensity of the radio signals measured by the first measurement portion <NUM> and the second measurement portion <NUM>. It is preferable that the signal intensity calculation portion <NUM> uses an average of values measured plural times while the tire rotates one time because the positions of the sensors in the front-rear direction of the vehicle may be different depending on the rotation of the tire.

More specifically, the signal intensity calculation portion <NUM> calculates the total value (R1 + R2) of the signal intensity described below, similar to the first embodiment.

<FIG> is a graph illustrating an example of the measured intensity of the radio signals and the calculation result. The signal intensity calculation portion <NUM> calculates the total value (R1 + R2) shown in <FIG>, for each sensor. The content of <FIG> is further described below.

Further, the signal intensity calculation portion <NUM> calculates an intensity ratio, which is a ratio using the first signal intensity and the second signal intensity, for each sensor. In the present embodiment, the signal intensity calculation portion <NUM> calculates a quotient of the first signal intensity and the second signal intensity as the intensity ratio for each sensor. Specifically, the signal intensity calculation portion <NUM> calculates the quotient (R1 / R2) obtained by dividing the first signal intensity by the second signal intensity. More specifically, the signal intensity calculation portion <NUM> calculates the quotients (R1 / R2) of the signal intensity described below.

The intensity ratio is not limited to R1 / R2 as long as the ratio uses the first signal intensity and the second signal intensity. R2 / R1 may be adopted as a quotient, or alternatively a formula such as (R1 - R2) / (R1 + R2) may be adopted as long as the values of R1 and R2 are made dimensionless.

The region determination portion <NUM> according to the present embodiment also determines that each sensor is located in which region in the vehicle <NUM>, based on the magnitude relation between the total values (R1 + R2) of the signal intensity calculated by the signal intensity calculation portion <NUM>. That is, the region determination portion <NUM> specifies an approximate position of each sensor in the vehicle <NUM>, based on the magnitude relation between the total values.

Specifically, the region determination portion <NUM> determines that the sensor is located in a front region of the vehicle <NUM> or a rear region of the vehicle <NUM>, based on the magnitude relation of the total values. That is, the region determination portion <NUM> determines that each sensor is located in which region in a plane view of the vehicle <NUM> shown in <FIG>.

As shown in <FIG>, a region in the vehicle <NUM> is divided into a region α (front region) and a region β (rear region). The region α includes the wheel positions <NUM> and <NUM> (left front wheel and right front wheel). The region β includes the wheel positions <NUM>, <NUM>, <NUM> and <NUM> (left rear outer wheel, left rear inner wheel, right rear inner wheel, and right rear outer wheel).

The region determination portion <NUM> determines that which sensor is located in which region, based on the magnitude relation between the total values (R1 + R2) shown in <FIG>. Specifically, the wheel positions <NUM> and <NUM> are extremely close to the receiver <NUM> (R1) and the receiver <NUM> (R2), and therefore each of the total values R1(a) + R2(a) and R1(b) + R2(b) are larger than the total values (R1 + R2) of other sensors. Accordingly, it can be determined that the sensor is located in the region α or the region β by using the total values (R1 + R2).

The position detection portion <NUM> according to the present embodiment detects the wheel position to which the tire having the sensor is mounted, based on the first signal intensity, the second signal intensity, the total value, and the quotient of each sensor.

Specifically, the position detection portion <NUM> detects that the tire having the sensor is mounted to which wheel position (position <NUM> or <NUM>) in the region α (front region), based on the magnitude relation between the first signal intensity and the second signal intensity.

That is, it can be determined that each of two sensors determined to be located in the region α by the region determination portion <NUM> is located at which wheel position (position) at a left side or a right side, based on the magnitude relation of the first signal intensity and the second signal intensity of the sensor. It is specifically because that, as shown in <FIG> and <FIG>, since the sensor <NUM> (sensor ID: a) is located at the left side of the vehicle, the intensity (first signal intensity) of the radio signal received by the receiver <NUM> (R1) is larger than the intensity (second signal intensity) of the radio signal received by the receiver <NUM> (R2).

The position detection portion <NUM> according to the present embodiment also detects that the tire <NUM> having the sensor <NUM> (sensor ID: a) is mounted to the wheel position <NUM> within the region (region α), based on the magnitude relation between the first signal intensity (R1(a)) and the second signal intensity (R2(a)). The position detection portion <NUM> detects that other sensor (tire) is mounted to which wheel position, by means of a similar procedure.

Further, the position detection portion <NUM> detects that the tire having the sensor is mounted to which wheel position (position) within the region β (rear region), based on the quotient (R1 / R2). Specifically, as shown in <FIG> and <FIG>, the quotients R1 / R2 fulfill an inequality of the quotient at the position <NUM> > the quotient at the position <NUM> > the quotient at the position <NUM> > the quotient at the position <NUM>. In <FIG> or the like, it is shown that the receiver R1 is the closest to the wheel position <NUM>, however in actual, since the radio signal is affected by the transmission environment in the vehicle <NUM>, in the present embodiment, the quotients R1 / R2 fulfill the inequality of the quotient at the position <NUM> > the quotient at the position <NUM> > the quotient at the position <NUM> > the quotient at the position <NUM>.

Since the quotient R1 / R2 denotes the ratio of "the intensity of the radio signal transmitted to the receiver <NUM> (R1) against the intensity of the radio signal transmitted to the receiver <NUM> (R2)", it can be determined that, as the quotient R1 / R2 is larger, the sensor is closer to the receiver <NUM> (R1).

Next, operation of the tire mount position detection system <NUM> according to the present embodiment will be described. Specifically, a tire (sensor) position detection operation of the tire mount position detection system <NUM> will be described. The initial setting operation is similar to that in the first embodiment.

<FIG> is a flow chart illustrating a flow of the tire (sensor) position detection operation of the tire mount position detection system <NUM>. As shown in <FIG>, the tire mount position detection system <NUM> acquires the signal intensity of the radio signal, which is transmitted by each sensor, received by the receiver R1 and the receiver R2 (S210).

The tire mount position detection system <NUM> calculates the total value of the signal intensity of the radio signal received by the receiver R1 and the signal intensity of the radio signal received by the receiver R2, for each sensor (S220). Here, the total value is described as R1(x) + R2 (x) (x denotes the sensor ID). The tire mount position detection system <NUM> repeats the calculation of the total value for each wheel (S230).

As shown in <FIG>, the sum of the received intensity (R1(x) + R2(x)) (total value) is classified into two groups. Based on the configuration that the sensors <NUM> to <NUM> (sensor IDs: a to f) are installed (mounted) to the tires <NUM> to <NUM>, the two groups correspond to two regions α and β depending on the distances from the receivers R1 and R2 (see <FIG>).

The tire mount position detection system <NUM> determines that each sensor is located in which region α or β, based on the calculation result of the total value (S240). Specifically, as shown in <FIG>, the tire mount position detection system <NUM> determines that the sensor <NUM> (sensor ID: a, total value: <NUM> V) and the sensor <NUM> (sensor ID: b, total value: <NUM> V) having the larger value of R1(x) + R2(x) are located in the region α.

Further, the tire mount position detection system <NUM> determines that other sensors (sensors <NUM> to <NUM>) having R1(x) + R2(x) smaller than that of the sensors <NUM> and <NUM> are located in the region β.

Next, the tire mount position detection system <NUM> calculates the quotient (R1(x) / R2(x)) for each sensor (S250). The tire mount position detection system <NUM> repeats the calculation of the quotient for each wheel (S260). However, the sensor (sensors <NUM> and <NUM>) determined as being located in the region α may be excluded from a target of the calculation.

The tire mount position detection system <NUM> detects the wheel position (positions <NUM> to <NUM>) to which the sensor (tire) is mounted, for each sensor (S270).

Specifically, the tire mount position detection system <NUM> detects that each of the sensors <NUM> and <NUM>, which are determined as being located in the region α, is located at which wheel position (position) at the left side and the right side. As shown in <FIG>, regarding the sensor <NUM> (sensor ID: a), R1(a) > R2(a) is fulfilled. On the other hand, regarding the sensor <NUM> (sensor ID: b), R1(b) < R2(b) is fulfilled. Consequently, it is detected that the sensor <NUM> in which R1(a) is larger than R2(a) is located at the left side (position <NUM>) of the vehicle and the sensor <NUM> in which R2(b) is larger than R1(b) is located at the right side (position <NUM>) of the vehicle.

Further, the tire mount position detection system <NUM> detects that each of the sensors <NUM> to <NUM>, which are determined as being located in the region β, is located at which wheel position (position) in the region β. As shown in <FIG>, the value R1 / R2 becomes small from the sensor <NUM> (sensor ID: c) to the sensor <NUM> (sensor ID: d), the sensor <NUM> (sensor ID: e), and the sensor <NUM> (sensor ID: f) in this order.

The tire mount position detection system <NUM> detects that the sensor having the largest value of R1 / R2 (<NUM>) is located at the position <NUM>, which is the closest position to the receiver <NUM> (R1) (transmission loss of the radio signal until the radio signal arrives at the receiver R1 is the smallest). Similarly, the tire mount position detection system <NUM> detects that the sensor <NUM> having the second largest value of R1 / R2 (<NUM>) is located at the position <NUM>, the sensor <NUM> having the third largest value of R1 / R2 (<NUM>) is located at the position <NUM>, and the sensor <NUM> having the smallest value of R1 / R2 (<NUM>) is located at the position <NUM>.

According to the embodiment described above, the following functions and effects are obtained. Specifically, according to the tire mount position detection system <NUM>, the wheel position to which the tire having the sensor is mounted is detected, based on the total value (R1(x) + R2(x)) of the first signal intensity (R1(x)), which is the intensity of the radio signal transmitted from the sensor (transmitter) and received by the receiver <NUM>, and the second signal intensity (R2(x)), which is the intensity of the radio signal transmitted from the sensor (transmitter) and received by the receiver <NUM>, and the quotient (R1(x) / R2(x)) of the first signal intensity and the second signal intensity.

More specifically, it is determined that the sensor (transmitter) is located in which region α, or β, based on the magnitude relation of the total values. And then, it is detected that the tire having the sensor (transmitter) is mounted to which wheel position within the region α, based on the magnitude relation between the first signal intensity and the second signal intensity, and it is detected that the tire having the sensor is mounted to which wheel position within the region β, based on the quotient.

The present embodiment adopts the quotient (R1 / R2). With this, even in a case in which the intensity (output) of the radio signal transmitted by each sensor is varied, the influence of the variation can be avoided. By using the ratio R1/ R2, the influence of the variation can be decreased compared to a configuration merely using an absolute value of the intensity of the radio signal, and thereby the wheel position can be detected more precisely.

In the present embodiment, the vehicle <NUM> is supposed as a large vehicle such as a mine vehicle. Accordingly, even in the vehicle such as a mine vehicle having a long distance between the sensor and the receiver and having a structure (fuel tank, thick tire, or the like) that largely affects the transmission environment of the radio signal, the wheel position to which the tire (sensor) is mounted can be detected more precisely.

As described above, the contents of the present invention are described with reference to the examples, however the present invention is not limited to those descriptions. It is obvious for a person skilled in the art to adopt various modifications and improvement.

For example, in the embodiments described above, the vehicle <NUM> having the front axle <NUM> and the rear axle <NUM> (double tire) is described as an example, however the present invention can be applied to other kind of vehicles.

<FIG> is a schematic plane view of a vehicle 10A according to other embodiment. As shown in <FIG>, the vehicle 10A is provided with a tractor <NUM> and a trailer <NUM>.

The tractor <NUM> has a front axle <NUM> and a rear axle <NUM> (double tire). The trailer <NUM> has a trailer front axle <NUM> and a trailer rear axle <NUM>. That is, the vehicle 10A is formed as a semi-trailer.

In the vehicle 10A, a receiver <NUM> and a receiver <NUM> are arranged in the tractor <NUM>, similar to the vehicle <NUM>. Further, a receiver <NUM> and a receiver <NUM> are arranged in the trailer <NUM>. Specifically, the receiver <NUM> and the receiver <NUM> are arranged adjacent to a front of the trailer front axle <NUM>. More specifically, the receiver <NUM> is arranged at an inner side of the vehicle with respect to the front of a left wheel of the trailer front axle <NUM>, and the receiver <NUM> is arranged at the inner side of the vehicle with respect to the front of a right wheel of the trailer front axle <NUM>.

Eight wheel positions of the trailer <NUM> are identified by four regions shown in <FIG>, specifically two regions surrounded by a one-dot chain line (a side of the trailer front axle <NUM> and a side of the trailer rear axle <NUM>) and two regions surrounded by a two-dot chain line (a side of the trailer front axle <NUM> and a side of the trailer rear axle <NUM>).

Further, a receiver (illustrated by a dotted line in <FIG>) may be added at a center portion of the trailer rear axle <NUM> in a vehicle width direction in order to improve the detection accuracy of the wheel position. This receiver can derive the improvement of the accuracy for determining the region, however the receiver cannot derive the improvement of the accuracy for detecting the wheel position within the region because the distances from the respective wheel positions are identical.

Further, three or more receivers may be arranged also in the vehicle <NUM>. <FIG> is a schematic plane view of a vehicle <NUM> including a tire mount position detection system 100A according to other embodiment.

As shown in <FIG>, the tire mount position detection system 100A is provided with a receiver unit 105A. The receiver unit 105A is formed by three receivers, specifically a receiver <NUM>, a receiver <NUM>, and a receiver <NUM> (R3).

The receiver <NUM> is arranged at or adjacent to a center portion of a rear axle <NUM> in a vehicle width direction. The tire mount position detection system 100A detects the wheel position to which each sensor (tire) is mounted, based on the intensity of the radio signal received by the receiver <NUM>, the receiver <NUM>, and the receiver <NUM>. Here, data of the intensity of the radio signal received by the receiver <NUM> may be used supplementarily, for example, to improve the detection accuracy of the wheel position by the receiver <NUM> and the receiver <NUM>. Specifically, by using the receiver <NUM>, the accuracy for distinguishing the region β and the region γ can be improved. However, since the distances of the receiver <NUM> from the wheel positions <NUM> and <NUM> (left rear inner wheel and right rear inner wheel) are identical and the distances of the receiver <NUM> from the wheel positions <NUM> and <NUM> (left rear outer wheel and right rear outer wheel) are identical, the receiver <NUM> does not derive the improvement of the accuracy for detecting the wheel position.

Further, the position where the receiver is arranged in the vehicle <NUM> may be modified as below. <FIG> is a schematic plane view of a vehicle <NUM> illustrating an arrangement example of a receiver 110A and a receiver 120A according to other embodiment.

As shown in <FIG>, both of the receiver 110A (first receiver) and the receiver 120A (second receiver) are arranged at a side of the wheel position <NUM> (right front wheel), namely arranged at one side with respect to the center line CL (see <FIG>).

In this case, the wheel position is detected in a region illustrated by a one-dot chain line or a region illustrated by a two-dot chain line shown in <FIG>. Although the detection accuracy of the wheel position may be deteriorated compared to the arrangement example of the receiver <NUM> and the receiver <NUM> shown in <FIG>, the wheel position can be also detected by the arrangement example of the receivers shown in <FIG>.

Further, in the embodiments described above, the receiver <NUM> and the receiver <NUM> are arranged at the same position in the front-rear direction (longitudinal direction) of the vehicle <NUM>, namely arranged to be aligned in the vehicle width direction, however the receiver <NUM> and the receiver <NUM> may be arranged at different positions in the front-rear direction of the vehicle <NUM>. That is, the receiver <NUM> and the receiver <NUM> may be offset to each other in the front-rear direction of the vehicle <NUM>. However, it is preferable that a structure (axle configuration) in the front-rear direction of the vehicle is symmetry like the vehicle <NUM> or the tractor <NUM>.

Further, in the embodiments described above, two wheels are included in each region, however three or more wheels may be included in each region. For example, the wheel, which is the closest to the receiver <NUM> (R1) (the intensity of the radio wave is the strongest), may be set as a wheel position <NUM>, and the wheel, which is the second closest to the receiver <NUM> (R1), may be set as a wheel position <NUM>.

In the embodiments described above, the position detection device <NUM> is installed as a part of the electronic control unit (ECU) mounted to the vehicle <NUM>, however the function achieved by the position detection device <NUM> may be provided at an outside of the vehicle <NUM>.

<FIG> is a schematic network configuration view including a schematic plane view of a vehicle 10B according to another embodiment. As shown in <FIG>, the vehicle 10B is provided a communication device <NUM> instead of the position detection device <NUM>.

The communication device <NUM> can execute radio communication with a radio base station <NUM>. The communication device <NUM> is formed by, for example, a radio communication terminal connectable to a mobile communication network (LTE or the like).

A server computer <NUM> is arranged on the communication network so as to achieve the functions (the first measurement portion <NUM>, the second measurement portion <NUM>, the signal intensity calculation portion <NUM>, the region determination portion <NUM>, and the position detection portion <NUM>), which are achieved by the position detection device <NUM> as described above.

Further, a program (software) that achieves the functions may be stored on the communication network in a downloadable state, or may be provided by a storage medium in which the program is stored.

Further, in the embodiments described above, the region determination portion <NUM> is arranged, however the position detection portion <NUM> may be formed to directly detect the wheel position to which each sensor is mounted, without arranging the region determination portion <NUM>.

Further, in the embodiments described above, the radio signal transmitted by the sensor (transmitter) includes the identifier (sensor ID) that identifies the sensor (transmitter), however such an identifier is not always needed in a case in which the sensor can be identified by other method (for example, a method using a frequency band, a channel number or the like).

Further, in the embodiments described above, the quotient R1 / R2 is adopted as the quotient of the first signal intensity and the second signal intensity, however a quotient R2 / R1 may be adopted instead of the quotient R1 / R2. In a case in which the quotient R2 / R1 is adopted, the inequality of the quotient at the position <NUM> > the quotient at the position <NUM> > the quotient at the position <NUM> > the quotient at the position <NUM> is fulfilled, however a similar result can be obtained.

Claim 1:
A tire mount position detection system (<NUM>) that detects each tire (<NUM> to <NUM>) having a transmitter (<NUM> to <NUM>) is mounted to which wheel position in a vehicle (<NUM>), the tire mount position detection system (<NUM>) comprising:
a receiver unit (<NUM>) arranged in the vehicle (<NUM>) to receive a radio signal transmitted by the transmitter (<NUM> to <NUM>), the receiver unit (<NUM>) comprising at least a first receiver (<NUM>), and a second receiver (<NUM>) arranged at a position different from a position of the first receiver (<NUM>);
a first measurement portion (<NUM>) that measures first signal intensity, which is intensity of the radio signal received by the first receiver (<NUM>), for each transmitter (<NUM> to <NUM>);
a second measurement portion (<NUM>) that measures second signal intensity, which is intensity of the radio signal received by the second receiver (<NUM>), for each transmitter (<NUM> to <NUM>);
a calculation portion (<NUM>) that calculates a total value of the first signal intensity and the second signal intensity, for each transmitter (<NUM> to <NUM>); and
a position detection portion (<NUM>) that detects the wheel position to which the tire (<NUM> to <NUM>) having the transmitter (<NUM> to <NUM>) is mounted, based on the first signal intensity, the second signal intensity, and the total value of each transmitter (<NUM> to <NUM>), wherein:
the calculation portion (<NUM>) calculates the total value of the first signal intensity and the second signal intensity, and an intensity ratio, which is a ratio using the first signal intensity and the second signal intensity, for each transmitter (<NUM> to <NUM>); and
the position detection portion (<NUM>) detects the wheel position to which the tire having the transmitter (<NUM> to <NUM>) is mounted, based on the first signal intensity, the second signal intensity, the total value, and the intensity ratio of each transmitter (<NUM> to <NUM>).