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EP-4737140-A1 - DETECTION DEVICE, DEFLATION DETECTION METHOD, AND DEFLATION DETECTION PROGRAM FOR ONE-WHEEL DEFLATION OF TIRE

EP4737140A1EP 4737140 A1EP4737140 A1EP 4737140A1EP-4737140-A1

Abstract

A deflation detection device includes an acquisition unit, an index calculation unit, a storage unit, and a deflation determination unit. The acquisition unit is configured to acquire rotation speed information of each of tires included in a vehicle during running of the vehicle. The index calculation unit is configured to calculate a relative deflation index that compares a rotation speed of each of the tires, based on the acquired rotation speed information. The storage unit is configured to store the relative deflation index calculated at a first time point during a period when the vehicle makes a first run, as a reference value. The deflation determination unit is configured to determine whether or not deflation has occurred in one tire among the tires, based on the reference value and the relative deflation index calculated at a second time point after the first time point during the first run.

Inventors

  • MURATA, HIROKI
  • MASUDA, HIDETAKA

Assignees

  • SUMITOMO RUBBER INDUSTRIES, LTD.

Dates

Publication Date
20260506
Application Date
20250929

Claims (12)

  1. A deflation detection device (2) for one-wheel deflation, comprising: an acquisition unit (21) configured to acquire rotation speed information of each of tires (T FL , T FR , T RL , T RR ) included in a vehicle (1) during running of the vehicle (1); an index calculation unit (22) configured to calculate a relative deflation index that compares a rotation speed (V1, V2, V3, V4) of each of the tires (T FL , T FR , T RL , T RR ), based on the acquired rotation speed information; a storage unit (15) configured to store the relative deflation index calculated at a first time point during a period when the vehicle (1) makes a first run, as a reference value (R); and a deflation determination unit (25) configured to determine whether or not deflation has occurred in one tire among the tires (T FL , T FR , T RL , T RR ), based on the reference value (R) and the relative deflation index calculated at a second time point after the first time point during the first run.
  2. The deflation detection device (2) according to claim 1, further comprising a regression analysis unit (23) configured to, based on multiple data sets of an elapsed time (t) from start of the first run and the relative deflation index at the elapsed time (t), derive a regression equation with the relative deflation index as a response variable and the elapsed time (t) as an explanatory variable, wherein the deflation determination unit (25) further determines whether or not deflation has occurred in one tire among the tires (T FL , T FR , T RL , T RR ), based on a regression coefficient (M(k)) included in the regression equation.
  3. The deflation detection device (2) according to claim 1 or 2, further comprising a reset unit (20) configured to delete the reference value (R) from the storage unit (15) after the first run if, during the first run, it is not determined by the deflation determination unit (25) that deflation has occurred in the one tire.
  4. The deflation detection device (2) according to any one of claims 1 to 3, further comprising a trend derivation unit (24) configured to, based on multiple data sets of a time t(k) corresponding to a kth (k = 1, 2, ..., n) run of the vehicle (1) in time-series order and a representative value Q(k) of the relative deflation index calculated during the kth run, derive a time-series change trend of the representative value Q(k), wherein the deflation determination unit (25) further determines whether or not deflation has occurred in one tire among the tires (T FL , T FR , T RL , T RR ), based on the change trend.
  5. A deflation detection device (2) for one-wheel deflation, comprising: an acquisition unit (21) configured to acquire rotation speed information of each of tires (T FL , T FR , T RL , T RR ) included in a vehicle (1) during running of the vehicle (1); an index calculation unit (22) configured to calculate a relative deflation index that compares a rotation speed (V1, V2, V3, V4) of each of the tires (T FL , T FR , T RL , T RR ), based on the acquired rotation speed information; a regression analysis unit (23) configured to, based on multiple data sets of an elapsed time (t) from start of the first run and the relative deflation index at the elapsed time (t), derive a regression equation with the relative deflation index as a response variable and the elapsed time (t) as an explanatory variable, during a period when the vehicle (1) makes a first run; and a deflation determination unit (25) configured to determine whether or not deflation has occurred in one tire among the tires (T FL , T FR , T RL , T RR ), based on a regression coefficient (M(k)) included in the regression equation.
  6. A deflation detection device (2) for one-wheel deflation, comprising: an acquisition unit (21) configured to acquire rotation speed information of each of tires (T FL , T FR , T RL , T RR ) included in a vehicle (1) during running of the vehicle (1); an index calculation unit (22) configured to calculate a relative deflation index that compares a rotation speed (V1, V2, V3, V4) of each of the tires (T FL , T FR , T RL , T RR ), based on the acquired rotation speed information; a trend derivation unit (24) configured to, based on multiple data sets of a time t(k) corresponding to a kth (k = 1, 2, ..., n) run of the vehicle (1) in time-series order and a representative value Q(k) of the relative deflation index calculated during the kth run, derive a time-series change trend of the representative value Q(k); and a deflation determination unit (25) configured to determine whether or not deflation has occurred in one tire among the tires (T FL , T FR , T RL , T RR ), based on the change trend.
  7. A deflation detection method for one-wheel deflation, executed by one or more computers connected to a storage unit (15), the deflation detection method comprising: acquiring rotation speed information of each of tires (T FL , T FR , T RL , T RR ) included in a vehicle (1) during running of the vehicle (1) (S11); calculating a relative deflation index that compares a rotation speed (V1, V2, V3, V4) of each of the tires (T FL , T FR , T RL , T RR ), based on the acquired rotation speed information (S14, S17); storing the relative deflation index calculated at a first time point during a period when the vehicle (1) makes a first run, as a reference value (R) in the storage unit (15) (S14); and determining whether or not deflation has occurred in one tire among the tires (T FL , T FR , T RL , T RR ), based on the reference value (R) and the relative deflation index calculated at a second time point after the first time point during the first run (S18).
  8. A deflation detection method for one-wheel deflation, executed by one or more computers, the deflation detection method comprising: acquiring rotation speed information of each of tires (T FL , T FR , T RL , T RR ) included in a vehicle (1) during running of the vehicle (1) (S21, S27); calculating a relative deflation index that compares a rotation speed (V1, V2, V3, V4) of each of the tires (T FL , T FR , T RL , T RR ), based on the acquired rotation speed information (S24); based on multiple data sets of an elapsed time (t) from start of the first run and the relative deflation index at the elapsed time (t), deriving a regression equation with the relative deflation index as a response variable and the elapsed time (t) as an explanatory variable, during a period when the vehicle (1) makes a first run (S25); and determining whether or not deflation has occurred in one tire among the tires (T FL , T FR , T RL , T RR ), based on a regression coefficient (M(k)) included in the regression equation (S26).
  9. A deflation detection method for one-wheel deflation, executed by one or more computers, the deflation detection method comprising: acquiring rotation speed information of each of tires (T FL , T FR , T RL , T RR ) included in a vehicle (1) during running of the vehicle (1) (S30); calculating a relative deflation index that compares a rotation speed (V1, V2, V3, V4) of each of the tires (T FL , T FR , T RL , T RR ), based on the acquired rotation speed information (S33); based on multiple data sets of a time t(k) corresponding to a kth (k = 1, 2, ..., n) run of the vehicle (1) in time-series order and a representative value Q(k) of the relative deflation index calculated during the kth run, deriving a time-series change trend of the representative value Q(k) (S35); and determining whether or not deflation has occurred in one tire among the tires (T FL , T FR , T RL , T RR ), based on the change trend (S36).
  10. A deflation detection program for one-wheel deflation, causing one or more computers connected to a storage unit (15) to execute: acquiring rotation speed information of each of tires (T FL , T FR , T RL , T RR ) included in a vehicle (1) during running of the vehicle (1) (S11); calculating a relative deflation index that compares a rotation speed (V1, V2, V3, V4) of each of the tires (T FL , T FR , T RL , T RR ), based on the acquired rotation speed information (S14, S17); storing the relative deflation index calculated at a first time point during a period when the vehicle (1) makes a first run, as a reference value (R) in the storage unit (15) (S14); and determining whether or not deflation has occurred in one tire among the tires (T FL , T FR , T RL , T RR ), based on the reference value (R) and the relative deflation index calculated at a second time point after the first time point during the first run (S18).
  11. A deflation detection program for one-wheel deflation, causing one or more computers to execute: acquiring rotation speed information of each of tires (T FL , T FR , T RL , T RR ) included in a vehicle (1) during running of the vehicle (1) (S21, S27); calculating a relative deflation index that compares a rotation speed (V1, V2, V3, V4) of each of the tires (T FL , T FR , T RL , T RR ), based on the acquired rotation speed information (S24); based on multiple data sets of an elapsed time (t) from start of the first run and the relative deflation index at the elapsed time (t), deriving a regression equation with the relative deflation index as a response variable and the elapsed time (t) as an explanatory variable, during a period when the vehicle (1) makes a first run (S25); and determining whether or not deflation has occurred in one tire among the tires (T FL , T FR , T RL , T RR ), based on a regression coefficient (M(k)) included in the regression equation (S26).
  12. A deflation detection program for one-wheel deflation, causing one or more computers to execute: acquiring rotation speed information of each of tires (T FL , T FR , T RL , T RR ) included in a vehicle (1) during running of the vehicle (1) (S30); calculating a relative deflation index that compares a rotation speed (V1, V2, V3, V4) of each of the tires (T FL , T FR , T RL , T RR ), based on the acquired rotation speed information (S33); based on multiple data sets of a time t(k) corresponding to a kth (k = 1, 2, ..., n) run of the vehicle (1) in time-series order and a representative value Q(k) of the relative deflation index calculated during the kth run, deriving a time-series change trend of the representative value Q(k) (S35); and determining whether or not deflation has occurred in one tire among the tires (T FL , T FR , T RL , T RR ), based on the change trend (S36).

Description

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a detection device, a deflation detection method, and a deflation detection program for detecting one-wheel deflation of a tire included in a wheel. Background Art Conventionally, a system for automatically detecting deflation of a tire (tire pressure monitoring system; TPMS) has been studied. Information indicating that a tire has been deflated can be used, for example, to alert the driver. Methods for detecting deflation of a tire include a method in which, for example, a pressure sensor is mounted to a tire to directly measure the air pressure of the tire, and a method in which deflation of a tire is indirectly evaluated using another index. An example of the indirect method is a dynamic loaded radius (DLR) method. In the DLR method, a phenomenon that a deflated tire collapses during running, thereby reducing a dynamic loaded radius and causing the tire to rotate at a higher speed, is utilized, and deflation of the tire is inferred based on the rotation speed of the tire. Japanese Laid-Open Patent Publication No. 2017-149340 discloses deflation indexes DEL1 to DEL3 for inferring deflation according to the DLR method. In Japanese Laid-Open Patent Publication No. 2017-149340, DEL1 to DEL3 are defined as follows. Here, V1 to V4 are the rotation speeds of front left, front right, rear left, and rear right tires, respectively. DEL1=V1+V4/V2+V3−1×100% DEL2=V1+V2/V3+V4−1×100% DEL3=V1+V3/V2+V4−1×100% In deflation determination using a combination of the deflation indexes DEL1 to DEL3 described above, reference values for the deflation indexes DEL1 to DEL3 are stored in advance in a vehicle. Here, as disclosed in Japanese Laid-Open Patent Publication No. 2017-149340, in order to perform accurate deflation determination, it is necessary to update the reference values stored in the vehicle, after the air pressure of each tire is adjusted. Normally, the reference values are updated through an initialization operation by a driver on the vehicle. Various measures have been taken to prevent the driver from forgetting to perform the initialization operation described above or performing the initialization operation without adjusting the air pressure. However, from a viewpoint different from this, there has been a demand for a technology in which a decrease in the accuracy of deflation determination related to initialization is not something to be concerned about and that is useful for deflation detection. An object of the present invention is to provide a deflation detection device, a deflation detection method, and a deflation detection program for one-wheel deflation of a tire, which do not require an initialization operation. SUMMARY OF THE INVENTION A deflation detection device for one-wheel deflation according to a first aspect of the present invention includes an acquisition unit, an index calculation unit, a storage unit, and a deflation determination unit. The acquisition unit is configured to acquire rotation speed information of each of tires included in a vehicle during running of the vehicle. The index calculation unit is configured to calculate a relative deflation index that compares a rotation speed of each of the tires, based on the acquired rotation speed information. The storage unit is configured to store the relative deflation index calculated at a first time point during a period when the vehicle makes a first run, as a reference value. The deflation determination unit is configured to determine whether or not deflation has occurred in one tire among the tires, based on the reference value and the relative deflation index calculated at a second time point after the first time point during the first run. A deflation detection device according to a second aspect is the deflation detection device according to the first aspect, further including a regression analysis unit configured to, based on multiple data sets of an elapsed time from start of the first run and the relative deflation index at the elapsed time, derive a regression equation with the relative deflation index as a response variable and the elapsed time as an explanatory variable, wherein the deflation determination unit further determines whether or not deflation has occurred in one tire among the tires, based on a regression coefficient included in the regression equation. A deflation detection device according to a third aspect is the deflation detection device according to the first or second aspect, further including a reset unit configured to delete the reference value from the storage unit after the first run if, during the first run, it is not determined by the deflation determination unit that deflation has occurred in the one tire. A deflation detection device according to a fourth aspect is the deflation detection device according to any one of the first to third aspects, further including a trend derivation unit configured to, based on multiple