Engine idling speed control system and method for an internal combustion engine

• US 4,406,262 A
• Filed: 02/05/1982
• Issued: 09/27/1983
• Est. Priority Date: 04/24/1979
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Ikeura, Kenji
• Primary Examiner(s): Nelli, Raymond A.
• Application Number:
  US06/346,377
• Time in Patent Office: 599 Days
• Field of Search: 123/339, 123/340, 123/395, 123/349, 123/489, 123/440, 123/585, 123/586, 123/587, 123/588, 123/589, 123/325
• US Class Current: 123/339.17
• CPC Class Codes: F02D 31/005 by controlling a throttle by-pass
• CPC Class Codes: F02D 41/26 using computer, e.g. microprocessor
• CPC Class Codes: F02M 3/07 by positioning the throttle flap stop, or by changing the fuel flow cross-sectional area, by electrical, electromechanical or electropneumatic means, according to engine speed
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Disclosed is an electronic automatic control method and system for controlling an air flow rate for an internal combustion engine of an automotive vehicle. The system includes an open loop control and a feedback control which are selectively effected corresponding to engine condition. The system includes an engine or temperature range within which the system controls engine speed. The given temperature range corresponds to a normal ambient temperature range so as to improve warming up efficiency upon starting engine under cold engine conditions. The system further includes a means for determining a feedback control condition to effect feedback control at a specific engine condition. In the feedback condition, the variable rate of a control duty cycle pulse which is applied to an electrically operative air flow rate adjusting means, is determined corresponding to an actual engine speed and a difference between the actual engine speed and a reference engine speed determined corresponding to the engine or coolant temperature.

Claims

1. An engine idling speed control system for an internal combustion engine, which system includes a primary and auxiliary air induction system, an idle air control valve incorporated in said auxiliary air induction system, said idle air control value being associated with an electromagnetically operable actuator which controls opening and closing of said idle air control valve, which system comprises:

a first sensor for determining engine temperature and in response producing a first sensor signal;

a second sensor for determining revolution speed of the engine and in response producing a second sensor signal;

first means for determining a reference engine speed based on the value of said first sensor signal, said reference engine speed being maintained (1) at a first constant value when the determined engine temperature is lower than a first predetermined value, (2) at a second constant value when the engine temperature is in a normal engine temperature range which is defined by a second predetermined value, higher than said first predetermined value and a third predetermined value, higher than said second predetermined value, and (3) at a third constant value while the engine is in an overheated condition in which the engine temperature is higher than a predetermined fourth value, higher than said third predetermined value, said reference engine speed being varied linearly from said first constant value to said second constant value when the engine temperature is in a range between said first and second predetermined values and said reference engine speed is varied linearly from said second constant value to said third constant value when said engine temperature is in a range between said third and fourth predetermined values;

second means responsive to the second sensor signal and said first means for determining a difference between the determined engine speed and said reference engine speed and for determining a closed loop control value based on the determined difference, said second means producing a pulse signal having a duty cycle representative of the determined closed loop control value, said duty cycle defining the ratio of the opening and closing periods of said idle air control valve in order to control the engine speed to reduce the difference between the determined engine speed and the reference engine speed, and

means for feeding said pulse signal to said actuator.

2. A control system, as recited in claim 1, wherein said system further comprises third means for determining a first correction value of said reference engine speed based on an engine load condition, said third means including load sensitive means for sensing engine parameters and for determining said engine load.

3. A control system, as recited in claim 1, wherein said system further comprises fourth means for determining an engine condition with respect to inputs fed from said first and second sensors and said engine load sensitive means, said fourth means operating to selectively carry out open loop control and closed loop control based on said determined engine condition, said fourth means including a pulse signal generator producing a pulse signal and comprising a proportional component and an integral component for determining response characteristics of said pulse signal generator in the closed loop control.

4. A control system, as recited in claim 2, further including a battery and a fifth means for determining a second correction value of said reference engine speed in response to reduction of said battery voltage below a given value for a period of time exceeding a given time.

5. A control system, as recited in claim 1, 2 or 3, wherein said system is provided with a means for permitting manual correction of said duty cycle.

6. A control system, as recited in claim 2, wherein the engine is positioned within a vehicle having a transmission and an air conditioning unit and said engine load condition is determined depending on the kind of transmission, whether the transmission is in drive or neutral and whether said air conditioning unit is on or off.

7. A control system, as recited in claim 6, wherein said third means limits a minimum reference engine speed when the kind of transmission is the manually operative type, and said third means also limits a maximum reference engine speed when said transmission is shifted to the drive position.

8. A control system, as recited in claim 3, wherein said fourth means determines constants of said proportional component and integral component of said pulse signal generator based on said engine speed and difference between said engine speed and said reference engine speed in order to determine response characteristics of said pulse signal generator.

9. A control system, as recited in claim 8, wherein the constant of said proportional component is set to 0 when said engine speed exceeds said reference engine speed.

10. A control system as recited in claim 1, 2 or 3, wherein said first predetermined value is 30°

C. and said first constant value is 1400 r.p.m.

16. A control system, as recited in claim 1 or 11, wherein said temperature range is 0°

C. to 30°

C. and said reference engine speed within said given temperature range is 1400 r.p.m.

11. A control system for controlling an idle air flow rate for an internal combustion engine in an automotive vehicle comprising in combination:

a bypass passage provided in an air intake passage connecting an air intake and intake manifold of the internal combustion engine, said bypass passage bypassing a throttle valve provided in said intake air passage to connect said air intake to said intake manifold therethrough;

an intake air control valve means interposed within said bypass passage, said valve means including an electromagnetically operated actuator means which varies the ratio of opening and closing of said valve means in response to a control signal applied thereto, said control signal having a corresponding ratio for energizing and deenergizing said actuator means;

a microcomputer including an interface, memory unit and central processing unit, said microcomputer processing inputs for effecting open loop control or closed loop control for determining said control signal to be applied to said actuator means of said valve means;

a first sensor for measuring an engine temperature and in response generating a first sensor signal;

a second sensor for determining engine speed and in response producing a second sensor signal;

said microcomputer including first means for determining a reference engine speed based on the value of said first sensor signal, said reference engine speed being maintained (1) at a first constant value when the determined engine temperature is lower than a first predetermined value, (2) at a second constant value when the engine temperature is in a normal engine temperature range which is defined by a second predetermined value, higher than said first predetermined value and a third predetermined value higher than said second predetermined value, and (3) at a third constant value while the engine is in an overheated condition in which the engine temperature is higher than a predetermined fourth value higher than said third predetermined value, and said reference engine speed being varied linearly from said first constant value to said second constant value when the engine temperature is in a range between said first and second predetermined values; and

said reference engine speed is varied linearly from said second constant value to said third constant value when said engine temperature is in a range between said third and fourth predetermined values; and

said microcomputer including second means for determining said control signal for closed loop control based on said engine speed and a difference between said determined engine speed and said reference engine speed, said second means including a control signal generator having a proportional element determining a proportional constant for determining said control signal depending on the difference between the determined engine speed and the reference engine speed and an integral element determining an integral constant for determining said control signal depending on the determined engine speed and the difference between the determined engine speed and the reference engine speed.

12. A control system as recited in claim 11, wherein said vehicle has one of an automatic and manual transmission and said microcomputer further comprises:

third means for determining a first correction value for correcting said reference engine speed with respect to the kind of transmission, said third means increasing the minimum reference engine speed by a given amount when the transmission is a manual type; and

fourth means detecting a transmission gear position between a driving range and neutral range to determine a second correction value to further correct said reference engine speed depending on said transmission gear position, said fourth means limiting a maximum reference engine speed at a given value when said transmission is in driving position.

13. A control system, as recited in claim 11 or 12, wherein said vehicle includes an air conditioner and said microcomputer further comprising:

fifth means for determining third correction values for correcting said reference engine speed depending upon the on or off condition of the air conditioner.

14. A control system, as recited in claim 13, wherein said vehicle has a battery and said microcomputer further comprises:

sixth means for determining a fourth correction value for correcting said reference engine speed in response to a drop of the vehicle battery voltage below a given value, said sixth means increasing said reference engine speed by a given amount.

15. A control system as recited in claim 11, wherein said proportional element maintains the proportional constant at a given value when the determined engine speed is lower than said reference engine speed by at least a given amount, and reduces the proportional constant to approach 0 as said difference decreases and being maintained 0 when said determined engine speed is higher than said reference engine speed, and said integral element determines the integral constant based on both said actual engine speed and the absolute value of said difference.

17. A control system, as recited in claim 12, wherein said given rate for increasing said minimum reference engine speed when the transmission is a manual type, is 50 r.p.m.

18. A control system, as recited in claim 12, wherein said given maximum reference engine speed is 800 r.p.m.

19. A method for controlling air flow rate for an internal combustion engine,

comprising in steps:

a first step for determining a reference engine speed corresponding to the engine temperature, said first means including a table data indicative of reference engine speed corresponding each of engine temperature, said table data including a given temperature range to be kept the reference engine speed in a given even speed, said temperature range being a range of normal atmospheric temperature;

a second step for correcting said reference engine speed with respect to kind of transmission, and increasing minimum refernece engine speed at a given rate when the transmission is a manual type; and

a third step determing a transmission positions between a dring range and neutral range to further correct said reference engine speed corresponding said transmission position, and limiting a maximum reference engine speed at a give value when said transmission is in driving range;

a fourth step for correcting said reference engine speed corresponding to on and off position of an air conditioner mounted on the vehicle;

a fifth step for processing an actual engine speed data to determine difference between said actual engine speed and said reference engine speed and determine constants of a proportional element and intergral element of a control signal generator for generating a control signal in feedback control corresponding to said difference and said actual engine speed;

a sixth step for determining and generating pulse signal indicative of said pulse duty based on said control signal and outting said pulse signal to an electromagnetically operative actuator means of an intake air control valve means for varying the ratio of energized period and deenergized period of said actuator means for controlling air flow rate.

20. A method, as recited in claim 19, wherein said temperature range is 0°

C. to 30°

C. and said even engine speed is 1400 r.p.m.

21. A method, as recited in claim 19, wherein said given rate for increasing said minimum reference speed determined at second step when said transmission is a manual type, is 50 r.p.m. and said given maximum reference engine speed determined at the third step when the transmission is in drive range, is 800 r.p.m.

22. A method, as recited in claim 21, wherein said method further comprises a step for correcting said reference engine speed corresponding to dropping of a vehicle battery when the battery voltage is maintained below a given voltage more than a given period of time, and increasing said reference engine speed at a given rate.

23. A method, as recited in claim 22, wherein said give voltage is 12 volts and said given rate is 100 r.p.m., and incrementation of said reference engine speed in response to drop of the battery voltage is not carried out to exceed 800 r.p.m. of the reference engine speed.

24. A method, as recited in claim 19, wherein said control signal generator has a proportional element and integral element, constant of said proportional element being kept in a given even value when said actual engine speed is lower than said reference engine speed exceeding a given value, and being reduced to approach to zero corresponding decreasing of said difference and maintained zero when said actual engine speed is higher than said reference engine speed, a constant of said integration element being varied corresponding to both of said actual engine speed and the absolute value of said difference.

25. A method, as recited in claim 24, wherein said method further includes a step for checking over-flow with respect to value of said control signal which is indicated by eight bits of data in a range 127 to -128 and said overflow checking step defines a range of the value of said control signal by determining a maximum and minimum value when said value exceeds said range, said value is corrected to said maximum or minimum value.

26. The control system as set forth in claim 25, which further comprises third means for checking over-flow of said control signal value with respect to capacity of said second means.

27. A method for controlling an intake air control valve for an internal combustion engine, which control valve includes an electromagnetically controlled actuator,

comprising in steps:

a first step for determining a reference engine speed corresponding to the engine temperature, said first means including a table data indicative of reference engine speed corresponding to an engine temperature, said table data including a given temperature range to be maintained when the reference engine speed is in a given even speed, said temperature range being a range of normal atmospheric temperature;

a second step for correcting said reference engine speed with respect to the kind of transmission, and increasing minimum reference engine speed at a given rate when the transmission is a manual type;

a third step for determining transmission positions between a driving range and neutral range to further correct said reference engine speed corresponding to said transmission position, and limiting a maximum reference engine speed at a given value when said transmission is in driving range;

a fourth step for correcting said reference engine speed corresponding to on and off position of an air conditioner mounted on the vehicle;

a fifth step for processing actual engine speed data to determine differences between said actual engine speed and said reference engine speed and determine constants of a proportional element and integral element of a control signal generator for generating a control signal in feedback control corresponding to said difference and said actual engine speed;

a sixth step for determining the corrected air flow rate and generating a pulse signal indicative of a pulse duty based on said control signal indicative of the corrected air flow rate; and

a seventh step for putting said pulse signal to the electromagnetically operative actuator means of the intake air control valve means and for controlling the ratio of energized period and deenergized period of said actuator means for controlling air flow rate to said corrected value.

28. A method, as recited in claim 27, wherein said temperature range is 0°

C. to 30°

C. and said even engine speed is 1400 r.p.m.

29. A method, as recited in claim 27, wherein said given rate for increasing said minimum reference speed determined at the second step when said transmission is a manual type, is 50 r.p.m. and said given maximum reference engine speed determined at the third step when the transmission is in drive range, is 800 r.p.m.

30. A method, as recited in claim 29, wherein said method further comprises a step for correcting said reference engine speed corresponding to dropping of a vehicle battery when the battery voltage is maintained below a given voltage more than a given period of time, and increasing said reference engine speed at a given rate.

31. A method, as recited in claim 30, wherein said given voltage is 12 volts and said given rate is 100 r.p.m., and incrementation of said reference engine speed in response to drop of the battery voltage is not carried out to exceed 800 r.p.m. of the reference engine speed.

32. A method, as recited in claim 27, wherein said control signal generator has a proportional element and integral element, the constant of said proportional element being kept in a given even value when said actual engine speed is lower than said reference engine speed exceeding a given value, and being reduced to approach to zero corresponding decreasing of said difference and maintained zero when said actual engine speed is higher than said reference engine speed, a constant of said integration element being varied corresponding to both of said actual engine speed and the absolute value of said difference.

33. A method, as recited in claim 32, wherein said method further includes a step for checking over-flow with respect to the value of said control signal which is indicated by eight bits of data in a range 127 to -128 and said overflow checking step defines a range of the value of said control signal by determining a maximum and minimum value when said value exceeds said range, said value is corrected to said maximum or minimum value.

34. The control system as set forth in claim 28, wherein said control signal generator varies the gain constant of said integral component depending upon said second signal value and said difference.

35. An idle speed control system for an automobile internal combustion engine comprising:

a primary air induction system incorporating a throttle valve for controlling primary air flow therethrough;

an auxiliary air induction system bypassing said throttle valve and incorporating an idle air control valve for controlling auxiliary air flow rate;

an electromagnetically operable actuator associated with said idle air control valve for opening and closing said idle air control valve in response to a pulse signal having a duty cycle defined by a control value;

a first sensor for determining engine temperature and producing a first sensor signal representative of the determined engine temperature;

a second sensor determining engine revolution speed and producing a seond sensor signal representative of the determined engine speed;

a microcomputer including a memory storing predetermined reference engine speed data with respect to the determined engine temperature, said stored data including a first constant value to be accessed in response to said first sensor signal having a value lower than a first preset value, a second constant value to be accessed in response to the first sensor signal having a value in a range between a second preset value higher than said first preset value and third preset value higher than said preset value and a third constant value to be accessed response to the sensor signal having a value larger than a fourth preset value higher than said third preset value, said data corresponding to said first sensor signal value between said first and second preset values and said third and fourth preset values varying linerarly from said first constant value to said second constant value and from said second constant value to said third constant value, said microcomputer comparing the determined engine speed with the determined reference engine speed in order to obtain the difference therebetween, calculating a basic control value based on the obtained difference, correcting said basic control value based on a porportional constant determined depending on the determined difference and an integral constant determined depending on the determined difference and the determined engine speed, producing a pulse signal having a duty cycle representative of the control value for defining energized periods and deenergized periods of said actuator for closed loop control of said auxiliary air flow rate so that the engine speed is controlled to reduce the difference between the engine speed and reference speed to zero.

37. A control system as recited in claim 35, further including a vehicle transmission and wherein said microcomputer further includes means for determining a first correction value for correcting said reference engine speed with respect to the kind of transmission, said third means increasing the minimum reference engine speed by a given amount when the transmission is a manual type;

and

said microcomputer including fourth means for detecting driving range and neutral range transmission gear positions to determine a second correctior value to further correct said reference engine speed depending on said transmission gear position, said fourth means limiting a maximum reference engine speed at a given value when said transmission is in a driving position.

38. A control system, as recited in claim 35, 36 or 37, further including a vehicle air conditioner and wherein said microcomputer further includes fifth means for determining third correction values for correcting said reference engine speed depending upon the on or off condition of said air conditioner mounted on the vehicle.

39. A control system as recited in claim 38, further including a vehicle battery and wherein said microcomputer further includes sixth means for determining a fourth correction value for correcting said reference engine speed in response to a drop of said vehicle battery voltage below a given value, said sixth means increasing said reference engine speed by a given amount.

40. A control system as set forth in claim 35, wherein said microcomputer maintains the proportional constant at a given value when the determined engine speed is lower than said reference engine speed by at least a given amount, and gradually reduces the proportional constant to approach 0 as said difference decreases and being maintained at 0 when said determined engine speed is higher than said reference engine speed, said microcomputer developing said integral constant based on both of said actual engine speed and the absolute value of said difference.

41. The method as set forth in claim 37, wherein said porportional component is set at zero when said engine speed is higher than said target engine speed and is varied according to a predetermined non-linear characteristic with respect to said difference between the engine speed and the target engine speed when the engine speed is lower than said target engine speed.

36. An idle speed control system for an automotive internal combustion engine comprising:

a primary air induction system incorporating a throttle valve for controlling primary air flow therethrough;

an auxiliary air induction system bypassing said throttle valve and incorporating an idle air control valve for controlling auxiliary air flow rate;

an electromagnetically operable actuator associated with said idle air control valve for opening and closing said idle air control valve in response to a pulse signal having a duty cycle defined by a control value;

a first sensor for determining engine temperature and in response producing a first sensor signal;

a second sensor determining engine revolution speed and in response producing a second sensor signal;

a microcomputer including a memory storing predetermined reference engine speed data with respect to the determined engine temperature, said stored data including a first constant value to be accessed in response to said first sensor signal having a value lower than a first preset value, a second constant value to be accessed in response to the first sensor signal having a value in a range between a second preset value higher than said first preset value and a third preset value higher than said second preset value and a third constant value to be accessed in response to the sensor signal having a value larger than a fourth preset value higher than said third preset value, said data corresponding to said first sensor signal value between said first and second preset values and said third and fourth preset values varying linearly from said first constant value to said second constant value and from said second constant value to said third constant value, said microcomputer comparing the determined engine speed with the determined reference engine speed in order to obtain the difference therebetween, calculating a basic control value based on the obtained difference and said second sensor signal value, correcting said basic control value depending on the kind of transmission, either automatic or manual, and the determined engine speed, and producing a pulse signal having a duty cycle representative of the control value for defining energized periods and deenergized periods of said actuator for closed loop control of said auxiliary air flow rate so that the engine speed is controlled to reduce the difference between the engine speed and reference speed to zero.

42. An idle engine speed control system for an internal combustion engine, comprising:

a bypass passage through which idle air flows, bypassing a throttle valve in a primary air induction passage;

an idle air control valve operated by an electromagnetically operable actuator for controlling the flow rate of said idle air through said bypass passage;

an engine coolant temprature sensor means adapted for producing a temperature signal having a value representative of an engine coolant temperature;

an engine speed sensor means for producing an engine speed signal having a value proportional to a speed of said engine;

first means responsive to said temperature signal for determining a target engine speed, said first means producing a reference signal having a value representative of the target engine speed;

second means for comparing said engine speed signal value with said reference signal value to determine a difference therebetween, said second means producing a feedback control signal having a value in dependence of said difference to feedback control a duty cycle of said electromagnetically operable actuator to reduce to zero the difference between said engine speed and said target engine speed; and

a control signal generator means incorporated in said second means for determining said control, a proportional component and integral component thereof having respective gains that are variable depending upon said engine speed signal value for variation of a response characteristics of said control signal generator means in relation to variations of said engine speed.

43. The control system as set forth in claim 42, wherein said proportional and integral components include respective gain constants.

44. The control system as set forth in claim 43, wherein said control signal generator varies said gain constants depending upon a difference between said engine speed signal value and said reference signal value.

45. The control system as set forth in claim 44, wherein said control signal generator varies the gain constant of said proportional component to zero in a region wherein said second signal value is larger than said reference signal value and in accordance with a predetermined non-linear characteristic with respect to said difference in a region wherein said second signal value is smaller than said reference signal value.

46. The system as set forth in claim 42, wherein said first means includes means for determining said target engine speed by comparing said temperature signal value with first and second temperature thresholds defining a predetermined warmed engine temperature range and with third and fourth temperature thresholds which define a predetermined cold engine temperature range, said first means determining said target engine speed at a first predetermined constant value when said temperature signal value is maintained within said predetermined warmed engine temperature range and at a second predetermined constant value when said temperature signal value is maintained at said predetermined cold engine range.

47. The control system as set forth in claim 46, which further comprises an engine load sensor for producing a load signal having a value representative of a load condition on the engine, and fourth means responsive to said load signal for producing a first correction signal for correcting said reference signal value, said first correction signal being variable as a function of said load signal value.

48. The control system as set forth in claim 47, which further comprises fifth means for controlling said control signal to have a value determined depending upon said temperature signal value, for open loop controlling said electromagnetically operable actuator, and sixth means for detecting a predetermined feedback condition in engine operation and in response activating said second means and disabling said fifth means as said feedback condition is detected and otherwise activating said fifth means and disabling said second means.

49. The control system as set forth in claim 47, wherein the first correction signal produced by said fourth means has a correction coefficient for determining said first correction signal value, which correction coefficient is variable depending upon the kind of transmission, i.e., manual transmission or automatic transmission, transmission gear position, i.e, neutral or shifted positions and a switch position of an air conditioner, i.e. ON or OFF.

50. The control system as set forth in claim 49, which further comprises seventh means for limiting a minimum target engine speed when the transmission is a manual transmission and a maximum target engine speed when the transmission is shifted.

51. The control system as set forth in claim 50, wherein said target engine speed in the engine coolant temperature range between 0°

C. to 30°

C., is set at 1400 r.p.m.

52. A method for controlling an engine idling speed in an internal combustion engine having a primary air induction passage with a throttle valve, a bypass passage bypassing said throttle valve and passing idle air therethrough, and an idle air control valve with a valve actuator which is electromagnetically operable, comprising the steps of:

detecting a temperature condition of an engine coolant and in response producing a temperature signal having a value representative of the engine coolant temperature;

detecting an engine speed and in response producing an engine speed signal having a value porportional to said engine speed;

determining a target engine speed in dependence of said first signal value and in response producing a reference signal having a value representative of the target engine speed;

determining a proportional component of a control signal value in dependence of a difference between said engine speed signal value and said reference signal value;

determining an integral component of said control signal value in dependence of said engine speed signal value and said difference between said engine speed signal value and said reference signal value;

producing a control signal having said control signal value including said proportional component and said integral component for defining a duty cycle of said valve actuator; and

feedback controlling said valve actuator with said control signal to reduce to zero the difference between the engine speed and the target engine speed.