Electronic control unit and method for measuring engine soak time

• US 6,618,666 B2
• Filed: 06/06/2001
• Issued: 09/09/2003
• Est. Priority Date: 06/29/2000
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Sugimura, Atsushi, Amano, Isao
• Primary Examiner(s): Vo, Hieu T.
• Application Number:
  US09/874,209
• Publication Number:
  US 20020013655A1
• Time in Patent Office: 825 Days
• Field of Search: 701/113, 701/114, 701/102, 701/115, 701/29, 701/35, 701/30
• US Class Current: 701/113
• CPC Class Codes: F02D 41/042 for stopping the engine
• CPC Class Codes: F02D 41/047 Taking into account fuel evaporation or wall wetting; special correction after fuel cut-off F02D41/126
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: F02D 41/249 Methods for preventing the loss of data
• CPC Class Codes: F02N 11/0848 with means for detecting successful engine start, e.g. to stop starter actuation
• CPC Class Codes: G07C 5/085 using electronic data carriers

Abstract

In an ECU for vehicles, a microcomputer operates with a main power from a battery, and a clock IC operates with sub power from the battery and measures time continuously irrespective of whether the microcomputer is operating. The microcomputer stores time data of the clock IC just before the supply of main power is turned off, and calculates a soak time or engine stop period from the stored time data and a current time data of the clock IC only after the supply of main power is turned on again and engine cranking is completed. This soak time represents the engine stop period. Operation of a cooling water temperature sensor or the like is checked by using the sensor output in relation to the calculated soak time.

Claims

1. An electronic control unit for a vehicle having an engine, the electronic control unit comprising:

a control part which operates and stops in accordance with state of a power supply voltage switched by a power supply switch;

a timing part which operates with the power supply voltage and measures time continuously irrespective of whether the control part is operating or stopped; and

a memory which stores measured time;

wherein the memory continues to store a time data of the timing part measured immediately before the engine is stopped, and

wherein the control part calculates a soak time of the engine from the stored time data and a current time data of the timing part when an engine cranking is completed.

2. The electronic control unit according to claim 1, wherein:

the control part detects completion of engine cranking from a rise of rotation speed of the engine to a predetermined speed.

3. The electronic control unit according to claim 1, wherein:

the control part continues to read in the time data of the timing part at every predetermined interval and updates the stored time data as long as the power supply voltage is applied thereto.

4. The electronic control unit according to claim 1, further comprising:

a water temperature sensor for detecting the temperature of cooling water of a vehicle engine,

wherein the control part determines abnormality of the temperature sensor from the calculated soak time and a detection value of the water temperature sensor.

5. A method of measuring soak time of an engine of a vehicle having a battery, a clock, a microcomputer, a memory and a starter, the method comprising the steps of:

continuously measuring time at every predetermined time by the clock supplied with electric power from the battery irrespective of operation of the engine;

storing and updating the measured time in the memory as long as the engine is in operation, and holding last-updated time by the memory when the engine stops operation;

supplying the electric power to the microcomputer before engine cranking by the starter;

detecting by the microcomputer a completion of engine cranking by the starter;

calculating soak time of the engine by the microcomputer using the last-updated time and latest time measured by the clock upon detection of the completion of engine cranking; and

using the calculated soak time to check operation condition of equipment of the engine.