Overheat preventing system for exhaust gas purifier of vehicles

• US 4,128,998 A
• Filed: 02/02/1977
• Issued: 12/12/1978
• Est. Priority Date: 06/26/1972
• Status: Expired due to Term

• Current Assignee: Nippon Soken, Inc. (DENSO Corporation)
• Original Assignee: Nippon Soken, Inc. (DENSO Corporation)
• Inventors: Hattori, Tadashi, Nakase, Takamichi, Iwata, Toshiharu, Tsubouchi, Hideo
• Primary Examiner(s): Hart, Douglas
• Application Number:
  US05/764,985
• Time in Patent Office: 678 Days
• Field of Search: 60/277, 60/288, 60/285
• US Class Current: 60/277
• CPC Class Codes: F01N 2390/02 using electric components only
• CPC Class Codes: F01N 2410/02 in case of high temperature, e.g. overheating of catalytic reactor
• CPC Class Codes: F01N 3/2053 By-passing catalytic reactors, e.g. to prevent overheating
• CPC Class Codes: F01N 9/00 Electrical control of exhaust gas treating apparatus monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00
• CPC Class Codes: F02D 41/1446 the characteristics being exhaust temperatures
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An overheat preventing system is provided for a vehicle exhaust gas purifier. The system comprises a temperature detector mounted in the locality of each of the exhaust ports of an engine, an overheat detector for detecting failure of an engine to fire from the temperature signals generated by the temperature detectors and for generating a signal, and an actuator for preventing the overheating of an exhaust gas purifier which is adapted to be operated upon the generation of the overheat signal from the overheat detector, whereby unburned gases are prevented from flowing into the exhaust gas purifier.

Claims

1. An overheat preventing system for exhaust gas purifier of a vehicle comprising:

a temperature detector inserted in the locality of each of a plurality of engine exhaust ports;

an overheat detector means for detecting failure of an engine to fire from signals from said temperature detectors to produce a signal, said overheat detector means detecting the time rate of change of the temperature in the locality of said engine exhaust ports, whereby when said temperature change rate reaches a predetermined value, the occurrence of a misfire is detected to generate an overheat signal; and

means responsive to said signal generated from said overheat detector means to pevent unburned gases from flowing into an exhaust gas purifier.

3. An overheat preventing system according to claim 1, wherein said means for preventing unburned gases from flowing into an exhaust gas purifier comprise means for closing the throttle valve of a carburetor.

5. An overheat preventing system according to claim 1, wherein said means for preventing unburned gases from flowing into an exhaust gas purifier comprise means for moving a bypass valve for a converter from one position to another.

7. An overheat preventing system according to claim 3, wherein said means for preventing unburned gases from flowing into an exhaust gas purifier further include means for moving a bypass valve for a converter from one position to another.

2. An overheat preventing system for exhaust gas purifier of a vehicle comprising:

a temperature detector inserted in the locality of each of a plurality of engine exhaust ports;

an overheat detector means for detecting failure of an engine to fire from signals from said temperature detectors to produce a signal, said overheat detector means generating temperature signals corresponding to the temperature in the locality of said exhaust ports, and a reference temperature signal produced from an engine rpm signal, said reference temperature signal representing a number of engine revolutions corresponding to a temperature in the locality of said exhaust ports which indicates the occurrence of a misfire, whereby each of said temperature signals is compared with said reference temperature signal so that when said reference temperature signal becomes higher than said temperature signal, the occurrence of a misfire and hence the generation of unburned gases is detected to generate an overheat signal; and

means responsive to said signal generated from said overheat detector means to prevent unburned gases from flowing into an exhaust gas purifier.

4. An overheat preventing system according to claim 2, wherein said means for preventing unburned gases from flowing into an exhaust gas purifier comprise means for closing the throttle valve of a carburetor.

6. An overheat preventing system according to claim 2, wherein said means for preventingg unburned gases from flowing into an exhaust gas purifier comprise means for moving a bypass valve for a converter from one position to another.

8. An overheat preventing system according to claim 4, wherein said means for preventing unburned gases from flowing into an exhaust gas purifier further include means for moving a bypass valve for a converter from one position to another.

9. An overheat prevention system for an exhaust gas purifier in an internal combustion engine having a plurality of engine exhaust ports and an ignition circuit for producing an engine rpm signal comprising:

a temperature detector inserted in the vicinity of each of the engine exhaust ports for detecting the temperature in the vicinity of the engine exhaust ports and for producing an output signal representing the detected temperature;

an overheat detector means connected to receive the output signals of said temperature detectors and the engine rpm signal of said ignition circuit,

said overheat detector means including,

a reference signal circuit for generating a reference signal in response to the engine rpm signal, and

a comparing circuit connected to said reference signal circuit for comparing the reference signal with each of the output signals of said temperature detectors and for generating a misfire signal when the output signal is smaller than the reference signal; and

means responsive to the misfire signal from said overheat detector for preventing unburned gases produced in the exhaust gases of the engine due to the failure to fire from flowing into an exhaust gas purifier.

10. An overheat prevention system according to claim 9, wherein said ignition circuit produces a pulse signal corresponding to the engine rpm signal, and

said reference temperature signal circuit comprises a conversion circuit for generating a reference signal of a D.C. voltage in response to the pulse signal.

11. An overheat prevention system for an exhaust gas purifier in an internal combustion engine having a plurality of engine exhaust ports and an ignition system for producing an ignition pulse signal comprising:

a temperature detector inserted in the vicinity of each of the engine exhaust ports for detecting the temperature in the vicinity of the engine exhaust port and for producing an output signal representing the detected temperature;

a control circuit connected to receive the output signal of said temperature detector and the ignition pulse signal of said ignition system, said control circuit including,

a temperature difference detecting circuit connected to receive signals from two of said temperature detectors for detecting a temperature difference therebetween,

a first comparing circuit connected to said temperature difference detecting circuit for comparing an output signal from said temperature difference circuit representing the temperature difference with a reference signal having a first predetermined value and for producing an output signal having different levels depending on whether the temperature difference exceeds the first predetermined value or not,

a highpass filter circuit to receive the ignition pulse signal and to convert the ignition pulse signal into a differential pulse signal,

an integrating circuit connected to said highpass filter circuit for generating an integrated voltage signal by integrating the differential pulse signal,

a second comparing circuit connected to said integrating circuit for generating an output signal identifying whether the integrated voltage signal does not exceed a second predetermined value or not, and

a decision circuit connected to said first and second comparing circuits and responsive to said output signals of said respective first and second comparing circuits for generating a misfire signal when the temperature difference signal exceeds the first predetermined value or the integrated voltage signal does not exceed the second predetermined value; and

means responsive to the misfire signal from said decision circuit for preventing unburned gases produced in the exhaust gases of the engine due to the failure to fire from flowing into an exhaust gas purifier.

12. An overheat preventing system according to claim 11, wherein the ignition pulse signal is a pulse signal generated by a high tension cord of said ignition system.

13. An overheat prevention system for an exhaust gas purifier in an internal combustion engine having a plurality of engine exhaust ports and an ignition system for producing an ignition pulse signal comprising:

a temperature detector inserted in the vicinity of each of the engine exhaust ports for detecting the temperature in the vicinity of the engine exhaust port and for producing an output signal representing the detected temperature;

a control circuit connected to receive the output signal of said temperature detector, said control circuit including,

a temperature difference detecting circuit connected to receive signals from two of said temperature detectors for detecting a temperature difference therebetween, and

a comparing circuit connected to said temperature difference detecting circuit for comparing an output signal from said temperature difference circuit representing the temperature difference with a reference signal having a predetermined value and for producing an output signal having different levels depending on whether the temperature difference exceeds the predetermined value or not,

said control circuit being further connected to receive ignition pulse signal of said ignition system, said control circuit further including,

a check circuit for detecting, depending on the ignition, pulse signal failure of all the cylinders of said engine to fire and for generating an output signal, and

a decision circuit connected to said comparing circuit and said check circuit for generating a misfire signal in response to the output signals of said comparing circuit and said check circuit; and

means responsive to the misfire signal from said control circuit for preventing unburned gases produced in the exhaust gases of the engine due to the failure to fire from flowing into an exhaust gas purifier.

14. An overheat preventing system according to claim 13, wherein said means for preventing unburned gases from flowing into an exhaust gas purifier comprise means for moving a bypass valve for a converter from one position to another.

15. An overheat preventing system according to claim 13, said means for preventing unburned gases from flowing into an exhaust gas purifier comprise means for closing the throttle valve of a carburetor.

16. An overheat preventing system according to claim 13, wherein said control circuit further detects a time rate of change of the temperature from said temperature signal from one of said temperature detectors, whereby when said temperature change rate exceeds a predetermined value, the generation of unburned gases which would cause an overheat is also detected to generate an overheat signal.