On-vehicle electronic control device

• US 8,036,790 B2
• Filed: 03/11/2009
• Issued: 10/11/2011
• Est. Priority Date: 07/02/2008
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Kannan, Yasuhiko, Nishida, Mitsunori, Kanzaki, Shozo
• Primary Examiner(s): Fleming; Faye M.
• Application Number:
  US12/402,186
• Publication Number:
  US 20100004811A1
• Time in Patent Office: 944 Days
• Field of Search: 701/36, 713/500, 307/11, 307/43
• US Class Current: 701/36
• CPC Class Codes: G07C 5/085 using electronic data carriers

Abstract

Provided is an on-vehicle electronic control device with low cost and low power consumption for performing monitoring control in both a driving mode and a parking mode of a vehicle. A main CPU is supplied with electric power from an on-vehicle battery via a power switching element and a main power supply circuit so as to control a plurality of electric loads in accordance with operating states of a plurality of input sensors. A sub CPU connected to the main CPU via a serial interface is supplied with electric power from the on-vehicle battery via a sub power supply circuit so as to monitor operations of the main CPU and input signals. The sub CPU has low speed and small memory capacity so as to operate with lower power consumption compared with the main CPU.

Claims

1. An on-vehicle electronic control device, comprising:

a main control circuit portion supplied with electric power from an on-vehicle battery via a power switching element responding to an operation of a power switch and a main power supply circuit, including a microprocessor as a main CPU of high speed and large-capacity memory area for driving a plurality of electric loads responding to operating states of a plurality of input sensors and contents of a first program memory; and

a sub control circuit portion including a middle speed clock signal source and a low speed clock signal source that are used selectively, supplied with electric power continuously from the on-vehicle battery via a sub power supply circuit, connected to the main CPU via a serial interface, and including a microprocessor as a sub CPU of middle speed and small-capacity memory area compared with the main CPU, wherein;

the sub CPU has a first operating mode, a second operating mode, and a third operating mode responding to a control program stored in a second program memory, and includes a power supply switch element for supplying with electric power to an input interface circuit;

the first operating mode is a parallel operating mode for operating based on a middle speed clock signal generated by the middle speed clock signal source in a closed state of the power switch, so as to operate in parallel with the main CPU and to communicate information with the main CPU, for detecting at least presence or absence of an abnormal state of a communication response in the main CPU and for monitoring an operating state of the main CPU;

the second operating mode is an individual operating mode for operating in a predetermined period of time after the power switch is opened and the main CPU stops its operation, while a power supply switch element for enabling a part of input signals of the sub CPU is closed, so as to monitor a parked state of a parked vehicle based on the enabled part of the input signals and to measure a lapse time after the power switch is opened, and the sub CPU operates based on the middle speed clock signal generated by the middle speed clock signal source;

the third operating mode is a time keeping only mode for operating based on a low speed clock signal generated by the low speed clock signal source, so as to measure a lapse time after the second operating mode is finished while the power supply switch element is opened in a period of time after the individual operation is finished until the power switch is closed again; and

a monitoring function of the operating state of the main CPU is stopped in the second operating mode and the third operating mode, and an operation result of the sub CPU in the second operating mode and the third operating mode is transmitted to the main CPU in the first operating mode.

2. An on-vehicle electronic control device according to claim 1, wherein the first operating mode further includes input and output communication means for transmitting an input signal from one of a second analog sensor and a second switch sensor connected to the sub CPU to the main CPU and for driving a second electric load connected to the sub CPU based on an output signal generated by the main CPU so as to bear a part of input and output control.

3. An on-vehicle electronic control device according to claim 2, wherein the first operating mode further includes abnormal state monitor processing means for performing diagnosis of presence or absence of an abnormal state in wiring on a part of input and output signals connected to one of the main CPU and the sub CPU and for monitoring a communication response operating state of the main CPU so as to perform one of warning of the abnormal state and stopping to drive a part of the plurality of electric loads if an abnormal state is detected in the communication response operating state.

4. An on-vehicle electronic control device according to claim 1, wherein:

the second operating mode performs parked state monitoring control of a part of inputs and outputs intermittently;

the second program memory includes a control program serving as clock switching means; and

the clock switching means is switch instruction generating means for selecting and using the middle speed clock signal source in a time zone while the sub CPU performs input and output control and for selecting and using the low speed clock signal source in a time zone while the sub CPU does not perform the input and output control.

5. An on-vehicle electronic control device according to claim 1, wherein:

the middle speed clock signal source is a clock signal source with relatively high accuracy using one of a ceramic resonator and a crystal resonator;

the low speed clock signal source is a semiconductor ring oscillator with low power consumption and low accuracy;

the second program memory further includes a control program serving as time keeping calibration means for enabling the middle speed clock signal source regularly in the third operating mode so as to measure a clock signal period of the low speed clock signal source with reference to a clock signal period of the middle speed clock signal source; and

the sub CPU performs a time keeping operation based on the measured clock signal period of the low speed clock signal source.

6. An on-vehicle electronic control device according to claim 1, wherein:

the sub CPU is supplied with at least a digital converted value of a pressure sensor for a fuel tank as parked state monitoring of the vehicle in the second operating mode;

the second program memory further includes a control program serving as evaporation detection means; and

the evaporation detection means monitors a change of pressure in the fuel tank in the second operating mode so as to judge presence or absence of fuel evaporation, and transmits, in the first operating mode, the presence or absence of an abnormal state of the fuel evaporation judged by the evaporation detection means to the main CPU.

7. An on-vehicle electronic control device according to claim 6, further comprising a solenoid for driving a ventilating valve, which is connected to a control output terminal of the sub CPU,

wherein the evaporation detection means judges the presence or absence of the fuel evaporation in the second operating mode by monitoring a change of pressure in the fuel tank that has been sealed after being opened to air by the solenoid for driving the ventilating valve.

8. An on-vehicle electronic control device according to claim 6, wherein:

a part of control constants used by the evaporation detection means stored in the second program memory is stored in the first program memory;

the first program memory includes a control program serving as control constant transmission means working together with the sub CPU in the first operating mode and a program serving as parking monitor information transmission means;

the control constant transmission means is means for transmitting control constants for evaporation detection written and stored in the first program memory in advance to a RAM memory cooperating with the sub CPU;

the parking monitor information transmission means is means for transmitting a fuel evaporation detection result detected by the sub CPU and a measurement result of parking time to the main CPU; and

the sub CPU performs fuel evaporation detection based on the control constants transmitted to the RAM memory and the control program serving as the evaporation detection means stored in the second program memory.

9. An on-vehicle electronic control device according to claim 8, wherein control of inputs and outputs in the second operating mode is performed regularly and intermittently so that the change of pressure in the fuel tank is monitored for performing the fuel evaporation detection, and includes a sensor abnormal state judging function, in which a change of temperature is monitored in parallel by a water temperature sensor for sensing temperature of cooling water for an engine so that an abnormal state of the water temperature sensor is judged.

10. An on-vehicle electronic control device according to claim 6, wherein:

the second program memory further includes a control program serving as requirement judging means for judging whether or not the evaporation detection means should be executed; and

the requirement judging means omits execution of the evaporation detection means this time and goes to the third operating mode if at least lapse time after the last evaporation judging until the present time is predetermined time or shorter.

11. An on-vehicle electronic control device according to claim 10, wherein the requirement judging means further includes means for responding to an abnormal state of a break or a short circuit about input and output circuit of the sub CPU and an abnormal state of decreasing voltage of the on-vehicle battery so as to omit execution of the evaporation detection means this time and to go to the third operating mode.

12. An on-vehicle electronic control device according to claim 6, wherein:

the second program memory further includes a control program serving as simple judging means concerning the evaporation detection means and a control program serving as precise judging means;

the simple judging means is means for performing a normal judging and for omitting a precise judging so as to go to the third operating mode if a pressure detected by the pressure sensor maintains a first pressure value close to ideal normal pressure in a first time period after the power switch is opened; and

the precise judging means is executed when the normal judging has not been performed by the simple judging means, performs the normal judging when the pressure detected by the pressure sensor maintains a second pressure value that deviates from the ideal normal pressure but enables an acceptance judging in a second time period that is longer than the first time period, and performs an abnormal judging so as to go to the third operating mode when the pressure detected by the pressure sensor does not maintain the second pressure value.

13. An on-vehicle electronic control device according to claim 12, wherein the sub CPU generates a pump drive output for decreasing or increasing inner pressure of a sealed fuel tank.

14. An on-vehicle electronic control device according to claim 13, wherein the first operating mode further includes a cap abnormal state judging function for judging presence or absence of an uncapped state of the fuel tank by generating the pump drive output in a closed state of the solenoid for driving the ventilating valve of the fuel tank and monitoring a detection signal of the pressure sensor.

15. An on-vehicle electronic control device according to claim 6, wherein the sub CPU is supplied with digital converted values from an environment temperature sensor and a fuel remaining quantity sensor so as to adjust one of a judged pressure and a judged lapse time in an evaporation detection.