Misfire detecting device for internal combustion engine

• US 3,924,457 A
• Filed: 03/28/1974
• Issued: 12/09/1975
• Est. Priority Date: 03/31/1973
• Status: Expired due to Term

• Current Assignee: Masao Kataoka, Masayoshi Ohtuka, Noboru Shibayama, Osamu Tutui, Shigehito Ozaki, Yujiro Oshima
• Original Assignee: Masao Kataoka, Masayoshi Ohtuka, Noboru Shibayama, Osamu Tutui, Shigehito Ozaki, Yujiro Oshima
• Inventors: Oshima, Yujiro, Kataoka, Masao, Tutui, Osamu, Shibayama, Noboru, Ohtuka, Masayoshi, Ozaki, Shigehito
• Primary Examiner(s): Myracle, Jerry W.
• Application Number:
  US05/455,941
• Time in Patent Office: 621 Days
• Field of Search: 73/116,115,117.3,35,389,118,119R,117.2
• US Class Current: 73/114.06
• CPC Class Codes: F02B 2075/027 four
• CPC Class Codes: G01L 23/24 specially adapted for measuring pressure in inlet or exhaust ducts of internal-combustion engines
• CPC Class Codes: G01M 15/106 using pressure sensors
• CPC Class Codes: G01M 15/11 by detecting misfire

Abstract

A misfire detecting device for an internal combustion engine includes an exhaust gas introducing tube which comprises tube means having openings at both ends thereof, one opening thereof being provided at a portion adjacent to an exhaust port in an exhaust passage in order to introduce the exhaust gas from a combustion chamber of the internal combustion engine which is of the piston type and the other opening thereof being provided at an exterior portion of the exhaust passage. A pressure transducer having a pressure sensing part is connected to the said other opening of the exhaust gas introducing tube, thereby converting a pressure fluctuation of the exhaust gas introduced by said exhaust gas introducing tube to an electrical signal. A signal processing circuit electrically connected to said pressure transducer detects a predetermined signal from said electrical signal of said pressure transducer. Thus the misfire detecting device converts a flow fluctuation of the exhaust gas in the exhaust passage to an electrical signal with said pressure transducer, detects a portion of the pressure fluctuation based on a misfire of the internal combustion engine from said electrical signal and thereby detects a misfire of the internal combustion engine.

Claims

1. A misfire detecting device for an internal combustion engine, comprising:

an exhaust gas introducing tube comprising tube means having openings at the both ends thereof, one opening thereof being provided at a portion adjacent to an exhaust port in an exhaust passage in order to introduce the exhaust gas from a combustion chamber of the internal combustion engine which is of a piston type and the other opening being provided exterior of the exhaust passage, a pressure transducer having a pressure sensing part connected to said other opening of said exhaust gas introducing tube;

thereby converting a pressure fluctuation of the exhaust gas introduced by said exhaust gas introducing tube to an electrical sigNal, a signal processing circuit electrically connected to said pressure transducer for detecting a predetermined signal from said electrical signal of said pressure transducer, a counter circuit connected to said signal processing circuit for counting the number of times of misfire of the internal combustion engine in a predetermined time period, whereby the flow fluctuation of the exhaust gas in the exhaust passage is converted to the electrical signal with said pressure transducer for detecting a portion of the pressure fluctuation based on a misfire of the internal combustion engine from said electrical signal, and thereby enabling the misfire of the internal combustion engine to be detected.

2. A misfire detecting device according to claim 1, wherein said counter circuit is a means for counting the number of times of misfire of the internal combustion engine and for displaying the counted number by a digital display.

3. a misfire detecting device according to claim 1, wherein said counter circuit is a means for counting the number of times of misfire of the internal combustion engine and for displaying the counted number by an analog display.

4. A misfire detecting device for an internal combustion engine, comprising:

an exhaust gas introducing tube comprising tube means having openings at the both ends thereof, one opening thereof being provided at a portion adjacent to an exhaust port in an exhaust passage in order to introduce the exhaust gas from a combustion chamber of the internal combustion engine which is of a piston type and the other opening being provided exterior of the exhaust passage, a pressure transducer having a pressure sensing part connected to said other opening of said exhaust gas introducing tube;

thereby converting a pressure fluctuation of the exhaust gas introduced by said exhaust gas introducing tube to an electrical signal, a signal processing circuit electrically connected to said pressure transducer for comparing a predetermined reference voltage and said electrical signal from said pressure transducer, whereby the flow fluctuation of the exhaust gas in the exhaust passage is converted to the electrical signal with said pressure transducer for detecting a portion of the pressure fluctuation based on a misfire of the internal combustion engine from said electrical signal, and thereby enabling the misfire of the internal combustion engine to be detected.

5. A misfire detecting device according to claim 4, further comprising a cooling adapter equipped to said pressure transducer, for cooling said pressure transducer with a predetermined thermal medium, thereby preventing said pressure transducer from overheating.

6. A misfire detecting device according to claim 5, wherein said cooling adapter comprises a double hollow cylinder having a thin inner wall, an annular chamber formed between said thin inner wall and an outer wall having two perforated holes in order to circulate said thermal medium therein, and two flange portions disposed at both ends to connect said inner and outer walls, said adapter being interposed between said exhaust gas introducing tube and said pressure transducer and a central hole surrounded by said inner wall being connected to the other opening of the exhaust gas introducing tube and the pressure sensing part of the pressure transducer.

7. A misfire detecting device according to claim 4 wherein said pressure transducer comprises a flexible diaphragm as said pressure sensing part and at least one strain sensing element attached to said flexible diaphragm to detect the misfire of the internal combustion engine.

8. A misfire detecting device according to claim 4, wherein:

said exhaust gas introducing tube is a stainless steel pipe disposed to penetrate an exhaust pipe of the internal combustion chamber, one opening of said exhaust gas introducing tube being disposed at a nearly central position of the exhaust passage and about 10 cm downstReam of an exhaust valve of the internal combustion engine, said pressure transducer comprises a casing comprising a hollow cylinder connected to the other opening of said gas introducing tube with an adapter, a cylinder member fixed to said casing, a flexible diaphragm attached to said cylinder member, two semiconductor strain sensing elements having mutually similar characteristics and being attached to an inside surface of said flexible diaphragm and being connected to a D.C. source in such a manner as to form a bridge circuit, said signal processing circuit comprises a comparator, a filter circuit which is connected to one input terminal of said comparator and which comprises two resistors, two condensers and a diode, a condenser connected to an output terminal of said bridge circuit of said pressure transducer and to said resistor of said filter circuit, and a circuit which is connected to the other input terminal of said comparator and which comprises a source, a resistor and a variable resistor.

9. A misfire detecting device according to claim 8, further comprising:

a counter circuit comprising a counter circuit part connected to sais signal processing circuit, a reset circuit part connected to said counter circuit part and, a time set circuit part connected to said counter circuit part and said reset circuit part, said counter circuit part comprising a gate circuit connected to said comparator of said signal processing circuit, a count display circuit connected to said gate circuit, a first processing circuit connected to said count display circuit, and an overflow display circuit connected to said first signal processing circuit, said reset circuit part comprising a switch, a capacitor connected to said switch, an input resistor connected to said capacitor, a power source connected to said input resistor, an inverter circuit connected to said capacitor, input resistor, said count display circuit and said first processing circuit of said counter circuit part, and a second processing circuit connected to said inverter circuit, said gate circuit and an overflow display circuit of said counter circuit part, said time set circuit part comprising a gate circuit connected to said second processing circuit of said reset circuit part, an oscillator connected to said gate circuit and an accumulator circuit connected to said gate circuit, said count display circuit and first processing circuit of said counter circuit part, and said second processing circuit of said reset circuit part.

10. A misfire detecting device for an internal combustion engine, comprising:

an exhaust gas introducing tube comprising tube means having openings at the both ends thereof, one opening thereof being provided at a portion adjacent to an exhaust port in an exhaust passage in order to introduce the exhaust gas from a combustion chamber of the internal combustion engine which is of a piston type and the other opening being provided exterior of the exhaust passage, a pressure transducer having a pressure sensing part connected to said other opening of said exhaust gas introducing tube;

thereby converting a pressure fluctuation of the exhaust gas introduced by said exhaust gas introducing tube to an electrical signal, a signal processing circuit electrically connected to said pressure transducer for comparing a constant voltage obtained by signal processing said electrical signal from said pressure transducer, and said electrical signal from said pressure transducer, whereby the flow fluctuation of the exhaust gas in the exhaust passage is converted to the electrical signal with said pressure transducer for detecting a portion of the pressure fluctuation based on a misfire of the internal combustion engine from said electrical signal, and thereby enabling the misfire of the internal combustion engine to be detected.

11. A misfire detecting device according to claim 10, wherein said exhaust gas introducing tube is an L-shaped stainless steel pipe disposed in the exhaust passage with a connecting spacer of an annular member, one opening of said exhaust gas introducing tube being disposed at a nearly central position of the exhaust passage and about 10 cm downstream of an exhaust valve of the internal combustion engine, said pressure transducer comprises a casing comprising a hollow cylinder, a cylinder member fixed to said casing, a flexible diaphragm attached to said cylinder member, two semiconductor strain sensing elements having mutually similar characteristics and being attached to the inside surface of said flexible diaphragm and being connected to a D.C. source in such a manner as to form a bridge circuit, said signal processing circuit comprises a comparator of which one input terminal is connected to an output terminal of said bridge circuit of said pressure transducer, a filter circuit comprising a condenser connected to said output terminal and a resistor connected to said condenser, and a divider connected to said resistor of said filter circuit and the other input terminal of said comparator.

12. A misfire detecting device according to claim 11, further comprising:

a counter circuit comprising a counter circuit part connected to said signal processing circuit, a reset circuit part connected to said counter circuit part, and a time set circuit part connected to said counter circuit part and said reset circuit part, said counter circuit part comprising a gate circuit connected to said comparator of said signal processing circuit, a memory circuit having a coupling capacitor connected to said gate circuit, two diodes, a transistor, a capacitor and an operational amplifier connected to said gate circuit, a comparing circuit having a first input resistor connected to said operational amplifier and a second input resistor, a power source and a comparator connected to said first and second input resistors, a display circuit having an input resistor connected to said operational amplifier and an amperemeter and an overflow display device connected to said comparator, said reset circuit part comprising a switch, a capacitor connected to said switch, an input resistor connected to said capacitor, a power source connected to said input resistor, an inverter circuit connected to said capacitor input resistor and said transistor of said memory circuit of said counter circuit part and a processing circuit connected to said inverter circuit, and said comparator of said comparing circuit of said counter circuit part, and said time set circuit part comprising a gate circuit connected to said processing circuit of said reset circuit part, an oscillator connected to said gate circuit, and an accumulator circuit connected to said gate circuit, said inverter circuit and said processing circuit of said reset circuit part.

13. A misfire detecting device for an internal combustion engine of the piston type comprising:

an exhaust gas introducing tube comprising tube means having openings at both ends thereof one opening thereof being provided in an exhaust passage sufficiently downstream of the exhaust port to a position where the exhaust gas flow is substantially smooth in order to introduce the exhaust gas from a combustion chamber of the internal combustion engine and the other opening being provided exterior of the exhaust passage, a pressure transducer having a pressure sensing part connected to said other opening of said exhaust gas introducing tube to convert a pressure fluctuation of the exhaust gas introduced by said exhaust gas introducing tube to an electrical signal, and a signal processing circuit electrically connected to said pressure transducer for receiving the electrical signal of said pressure transducer to detect the portion of the pressure fluctuation due to a misfire of the internal combustion engine to thereby detect the misfire of the internal combustion engine.

14. A misfire detecting devicE according to claim 13 further comprising a cooling adapter having an annular cooling chamber forming a cylindrical wall member, the annular cooling chamber being filled with a predetermined thermal medium and being interposed between said pressure transducer and said gas introducing tube for cooling both said pressure transducer and the exhaust gas in a portion surrounded by said annular cooling chamber with said predetermined thermal medium to prevent said pressure transducer from overheating.