ABNORMALITY DETERMINATION APPARATUS AND ABNORMALITY DETERMINATION METHOD FOR COOLANT TEMPERATURE SENSOR, AND ENGINE COOLING SYSTEM

• US 20130213324A1
• Filed: 11/08/2011
• Published: 08/22/2013
• Est. Priority Date: 11/11/2010
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Saitoh, Tatsuki
• Granted Patent: US 9,261,012 B2
• Time in Patent Office: Days
• US Class Current: 123/41.09
• CPC Class Codes: F01P 11/16 concerning coolant temperature F01P11/20 takes precedence
• CPC Class Codes: F01P 2005/105 Using two or more pumps
• CPC Class Codes: F01P 2007/146 using valves
• CPC Class Codes: F01P 2060/08 Cabin heater
• CPC Class Codes: F01P 2070/04 using electrical heating elements
• CPC Class Codes: F01P 7/16 by thermostatic control
• CPC Class Codes: F01P 7/165 characterised by systems with two or more loops

Abstract

When a temperature difference between intake air temperature that detected by an intake air temperature sensor and engine coolant temperature thw1 detected by an engine coolant temperature sensor is greater than a threshold value, a coolant temperature sensor abnormality determination apparatus opens a changeover valve to cause the coolant to flow into an engine coolant passageway, thereby mixing the coolant in an engine and the coolant in a heater passageway (bypass passageway). If the temperature difference between the engine coolant temperature thw1 and a heater inlet coolant temperature (bypass coolant temperature) thw2 occurring after the changeover valve opens is less than or equal to a predetermined value, the apparatus determines that the engine coolant temperature sensor is normal. If the temperature difference is greater than the predetermined value, the apparatus determines that the engine coolant temperature sensor is abnormal.

Claims

1. A coolant temperature sensor abnormality determination apparatus which is applied to an engine cooling system that includes a coolant passageway comprising an engine coolant passageway and a bypass passageway that bypasses an engine, a control valve that can be in an open state to allow mixing of coolant from the engine coolant passageway and coolant from the bypass passageway at a confluence between the engine coolant passageway and the bypass passageway and that can be in a closed state to restrict the mixing of the coolant from the engine coolant passageway and the coolant from the bypass passageway at the confluence between the engine coolant passageway and the bypass passageway, an engine coolant temperature sensor that detects engine coolant temperature in the engine coolant passageway, and a bypass coolant temperature sensor that is arranged in the coolant passageway, downstream of the confluence between the engine coolant passageway and the bypass passageway, the coolant temperature sensor abnormality determination apparatus comprising

a determination portion that opens the control valve when a difference between atmospheric temperature around the engine and the engine coolant temperature detected by the engine coolant temperature sensor at the time of start of the engine is greater than a threshold value, and that determines that the engine coolant temperature sensor is abnormal, if the difference between temperature detected by the engine coolant temperature sensor and temperature detected by the bypass coolant temperature sensor after the control valve opens is greater than a predetermined value.

2. The coolant temperature sensor abnormality determination apparatus according to claim 1, wherein the determination portion determines that the bypass coolant temperature sensor is normal if the difference between the atmospheric temperature and the temperature detected by the bypass coolant temperature sensor, in the closed state of the control valve, is within a predetermined range

3. The coolant temperature sensor abnormality determination apparatus according to claim 1, wherein:

the control valve is a temperature-sensitive operation valve that has a temperature sensitive portion that displaces a valve body; and

the coolant temperature sensor abnormality determination apparatus includes open-valve state determination portion that determines that the control valve has opened, when an estimated value of ambient coolant temperature of the control valve becomes equal to or greater than a valve-opening temperature of the control valve.

4. The coolant temperature sensor abnormality determination apparatus according to claim 1, wherein after a predetermined time elapses following opening of the control valve, the determination portion executes determination regarding the engine coolant temperature sensor.

5. A coolant temperature sensor abnormality determination method which is for use in an engine cooling system that includes a coolant passageway comprising an engine coolant passageway and a bypass passageway that bypasses an engine, a control valve that can be in an open state to allow mixing of coolant from the engine coolant passageway and coolant from the bypass passageway at a confluence between the engine coolant passageway and the bypass passageway and that can be in a closed state to restrict the mixing of the coolant from the engine coolant passageway and the coolant from the bypass passageway at the confluence between the engine coolant passageway and the bypass passageway, an engine coolant temperature sensor that detects engine coolant temperature in the engine coolant passageway, and a bypass coolant temperature sensor that is arranged in the coolant passageway, downstream of the confluence between the engine coolant passageway and the bypass passageway, the coolant temperature sensor abnormality determination method being comprising:

opening the control valve when a difference between atmospheric temperature around the engine and the engine coolant temperature detected by the engine coolant temperature sensor at the time of start of the engine is greater than a threshold value; and

determining that the engine coolant temperature sensor is abnormal, if the difference between temperature detected by the engine coolant temperature sensor and temperature detected by the bypass coolant temperature sensor after the control valve opens is greater than a predetermined value.

6. The coolant temperature sensor abnormality determination method according to claim 5, further comprising:

determining that the bypass coolant temperature sensor is normal if the difference between the atmospheric temperature and the temperature detected by the bypass coolant temperature sensor, in the closed state of the control valve, is within a predetermined range.

7. An engine cooling system comprising:

a coolant passageway comprising an engine coolant passageway and a bypass passageway that bypasses an engine;

a control valve that can be in an open state to allow mixing of coolant from the engine coolant passageway and coolant from the bypass passageway at a confluence between the engine coolant passageway and the bypass passageway and that can be in a closed state to restrict the mixing of the coolant from the engine coolant passageway and the coolant from the bypass passageway at the confluence between the engine coolant passageway and the bypass passageway;

an engine coolant temperature sensor that detects engine coolant temperature in the engine coolant passageway;

a bypass coolant temperature sensor that is arranged in the coolant passageway, downstream of the confluence between the engine coolant passageway and the bypass passageway; and

a coolant temperature sensor abnormality determination portion that opens the control valve when a difference between atmospheric temperature around the engine and the engine coolant temperature detected by the engine coolant temperature sensor at the time of start of the engine is greater than a threshold value, and that determines that the engine coolant temperature sensor is abnormal, if the difference between temperature detected by the engine coolant temperature sensor and temperature detected the bypass coolant temperature sensor after the control valve opens is greater than a predetermined value.