# US 12,761,108 B2 · Leak diagnosis apparatus

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- Number: US 12,761,108 B2
- Document ID: US12761108B2
- Status: Granted
- Kind: B2
- Application number: 18/606,841
- Filed: 2024-03-15
- Published: 2024-09-19
- Granted: 2026-10-13
- Earliest claimed: 2023-03-17
- Assignees: Toyota Jidosha Kabushiki Kaisha
- Applicants: Toyota Jidosha Kabushiki Kaisha
- Inventors: Keita Fukui; Yuusaku Nishimura; Hideki Miyahara; Yoshiyuki Hatano; Takayuki Yamada
- Web page: https://patentgrep.com/patent/US12761108B2

## CPC

- G01M 3/32: for containers, e.g. radiators
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR

## Abstract

A leak diagnosis apparatus for performing leak diagnosis of a fuel tank mounted on a vehicle, includes a calculation unit configured to calculate an amount of change in a pressure in the fuel tank and an amount of change in a temperature of a fuel in the fuel tank while an ignition is turned off, and a determination unit configured to determine whether a leak in the fuel tank is absent or present.

## Claims

### Claim 1

A leak diagnosis apparatus for performing leak diagnosis of a fuel tank mounted on a vehicle, comprising:
an electronic control unit including an arithmetic processing circuit and a memory, the electronic control unit being configured to:
calculate an amount of change in a pressure in the fuel tank and an amount of change in a temperature of a fuel in the fuel tank while an ignition is turned off,
determine whether a leak in the fuel tank is absent or present, acquire the pressure and an outside air temperature,
estimate a plurality of change patterns of the temperature of the fuel in the fuel tank based on a change in the outside air temperature,
specify a change pattern in which a difference between a maximum value of the temperature of the fuel in the fuel tank and a minimum value of the temperature of the fuel in the fuel tank is smallest among the plurality of change patterns, and
calculate a difference between the maximum value of the temperature of the fuel in the fuel tank and the minimum value of the temperature of the fuel in the fuel tank in the specified change pattern as the amount of change in the temperature of the fuel in the fuel tank, wherein the electronic control unit is configured to determine that the leak in the fuel tank is absent, when the amount of change in the pressure in the fuel tank is larger than a pressure determination value, and the electronic control unit is configured to determine that the leak in the fuel tank is present, when the amount of change in the pressure in the fuel tank is equal to or smaller than the pressure determination value and when the amount of change in the temperature of the fuel in the fuel tank is larger than a temperature determination value.

### Claim 2 (depends on 1)

The leak diagnosis apparatus according to claim 1, wherein
the electronic control unit is configured to calculate a difference between a maximum value of the pressure and a minimum value of the pressure while the ignition is turned off as the change amount of the pressure, and to calculate a difference between a maximum value of the temperature and a minimum value of the temperature while the ignition is turned off as the amount of change in the temperature, and
the temperature determination value is set based on a difference between a temperature of a saturated vapor of the fuel corresponding to the maximum value of the pressure and a temperature of the saturated vapor of the fuel corresponding to the minimum value of the pressure.

### Claim 3 (depends on 1)

The leak diagnosis apparatus according to claim 1, wherein when the amount of change in the pressure is equal to or smaller than the pressure determination value and when the amount of change in the temperature is equal to or smaller than the temperature determination value, the electronic control unit is configured not to determine whether the leak in the fuel tank is absent or present, and the electronic control unit is configured to continue to calculate the amount of change in the pressure and the amount of change in the temperature.