Control system

• US 20030033067A1
• Filed: 08/05/2002
• Published: 02/13/2003
• Est. Priority Date: 08/10/2001
• Status: Active Grant

• Current Assignee: Fujitsu Ten Limited (DENSO Corporation)
• Original Assignee: Fujitsu Ten Limited (DENSO Corporation)
• Inventors: Arita, Hiroshi, Kimura, Shuuji
• Granted Patent: US 6,898,499 B2
• Time in Patent Office: Days
• US Class Current: 701/48
• CPC Class Codes: B60R 16/03 for supply of electrical power to vehicle subsystems or for circuit arrangements for charging batteries H02J7/00
• CPC Class Codes: B60R 16/0315 using multiplexing techniques multiplexing for transmission of signals G08C15/00; multiplexing for electrical communication in general H04J
• CPC Class Codes: Y02T 10/92 Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles

Abstract

The present invention was accomplished in order to provide a control system which enables a considerable decrease in electric power consumption of backup power, leading to effective prevention of a dead battery, while data in each control unit which need be maintained even after power is turned off is properly maintained, wherein an ECU has a first transmitting means to transmit data which need be maintained to an ECU for storage when a change of an IGSW connected to a battery to the off position is detected, and a power supply cutoff means to cut off the power supply to the other ECUs after the completion of the transmission of data to the ECU for storage by the first transmitting means, while the ECU for storage has a first storage controlling means to store the data transmitted from the other ECUs in RAM, and a power switching means to detect the change of the IGSW to the off position and switch the power of the ECU for storage to the backup power.

Claims

1. A control system, wherein a first control unit and a second control unit perform data communications,

the first control unit and the second control unit sharing data with each other:

the first control unit, having;

a first transmitting means to transmit data which need be maintained to the second control unit when a change of a first switch connected to a power source to the off position is detected; and

a power supply cutoff means to cut off the power supply to the first control unit after the transmission of the data to the second control unit by the first transmitting means is completed; and

the second control unit, having;

a first storage controlling means to store the data transmitted from the first control unit in a first storage means; and

a power switching means to detect a change of the first switch to the off position and switch the power of the second control unit to backup power.

2. A control system according to claim 1, comprising:

the first control unit, having a first receiving means to receive the data transmitted from the second control unit when a change of the first switch to the on position is detected; and

the second control unit, having a second transmitting means to transmit the data stored in the first storage means to the first control unit, being a source of the data, when a change of the first switch to the on position is detected.

3. A control system according to claim 1, comprising a plurality of the first control units.

4. A control system according to claim 1, comprising a plurality of the second control units.

5. A control system according to claim 1, comprising:

the first transmitting means in the first control unit, transmitting the data to the second control unit multiple times;

the second control unit, having a data identifying means to judge whether or not the multiple transmitted data from the first control unit are identical with one another; and

the first storage controlling means, storing the data in the first storage means when the data identifying means judges the data to be identical with one another.

6. A control system according to claim 1, comprising:

the first transmitting means in the first control unit, transmitting the data periodically to the second control unit during the on state of the first switch.

7. A control system according to claim 1, comprising:

the first control unit, having;

a second storage means, being nonvolatile, which can maintain data even if power is not provided;

a second storage controlling means to store only a minimum of data required for normal control of the first control unit in the second storage means; and

a data reading means to read the data stored in the second storage means as necessary.

8. A control system according to claim 7, comprising:

the data reading means in the first control unit, which reads the data from the second storage means when data to be transmitted from the second control unit upon changing the first switch to the on position cannot be received; and

the first control unit, having a first used data controlling means to use the data read from the second storage means by the data reading means for control.

9. A control system according to claim 8, comprising:

the first control unit, having a first announcing means to announce the occurrence of an abnormal condition when data to be transmitted from the second control unit upon changing the first switch to the on position cannot be received.

10. A control system according to claim 7, comprising:

the data reading means in the first control unit, which reads the data from the second storage means upon changing the first switch to the on position;

the first control unit, having;

a data match judging means to judge whether or not the data read from the second storage means by the data reading means matches with the data transmitted from the second control unit; and

a second used data controlling means to use the data read from the second storage means for control when the data read from the second storage means and the data transmitted from the second control unit are judged not to match with each other by the data match judging means.

11. A control system according to claim 10, comprising:

the first control unit, having a second announcing means to announce the occurrence of an abnormal condition when both of the data are judged not to match with each other by the data match judging means.

12. A control system according to claim 8, comprising:

the first control unit, having an alternative data reading means to read a prescribed value stored as a fail safe value when data which is not kept in storage in the second storage means is required for control.

13. A control system according to claim 1, being mounted on a vehicle, wherein the second control unit is an ECU for body control or an ECU for security.

14. A control system according to claim 13, being mounted on a vehicle, wherein, when a plurality of the second control units are arranged, an ECU for engine control is included in the second control units.

15. A control system, wherein multiple control units can mutually perform data communications, comprising:

at least one control unit among multiple control units, having a nonvolatile storage means which can maintain the memory contents using backup power;

wherein the other control units transmit the memory contents which need be maintained to the control unit having the nonvolatile storage means when the power supply to the system is shut off.