Method and system for controlling idling speed for a Diesel engine

• US 4,616,615 A
• Filed: 01/12/1984
• Issued: 10/14/1986
• Est. Priority Date: 01/18/1983
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Saito, Hideyuki, Yasuhara, Seishi, Kawaguchi, Hiroyuki
• Primary Examiner(s): Miller, Carl Stuart
• Application Number:
  US06/570,260
• Time in Patent Office: 1,006 Days
• Field of Search: 123/339, 123/357, 123/358, 123/359, 123/458, 123/198 D
• US Class Current: 123/339.15
• CPC Class Codes: F02B 3/06 with compression ignition compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02
• CPC Class Codes: F02D 1/025 by means dependent on engine working temperature F02D1/08 takes precedence
• CPC Class Codes: F02D 1/14 pneumatic
• CPC Class Codes: F02D 31/007 controlling fuel supply
• CPC Class Codes: F02D 41/083 taking into account engine load variation, e.g. air-conditionning
• CPC Class Codes: F02D 41/38 of the high pressure type
• CPC Class Codes: F02M 59/447 means specially adapted to limit fuel delivery or to supply excess of fuel temporarily, e.g. for starting of the engine combined with fuel pump regulating devices F02D

Abstract

In a Diesel engine with a Bosch-type fuel pump or the like having a control lever which determines the fuel injection quantity, idling speed is controlled by a movable stopper which abuts the control lever to place a lower limit on fuel injection quantity during idling. A control unit derives a target idling speed value according to engine temperature, electrical load, etc. and controls the pneumatic actuator of the stopper in accordance with the difference between actual engine speed during idling and the target idling speed. When the engine is not idling, the pneumatic actuator may be controlled to act as a dashpot, damping the return of the control lever to its idling position. Electromagnetically controlled valves respond to the control unit by providing atmospheric pressure or negative pressure to the pneumatic actuator. An auxiliary valve is provided for bypassing a defective atmospheric pressure supplying valve.

Claims

1. A system for controlling the idling speed of a vehicular Diesel engine, the engine having a member for controlling an amount of fuel supplied to the engine according to the position thereof, comprising:

(a) A stop member, engaged with said control member during engine idling within a positional range said control member displaces, for limiting the amount of fuel supplied to the engine from said control member during engine idling;

(b) means for selectively adjusting a position of said stop member within the positional range of said control member during engine idling such that the engine idling speed approaches a target idling speed determined according to engine operating conditions at the time of idling,

(c) said means for selectively adjusting comprising;

(i) a pressure-responsive actuator linked with said stop member which actuates said stop member according to pressure introduced thereinto;

(ii) a normally closed first valve means which operatively opens to introduce a negative pressure into said actuator so that said control member mediates an increased amount of fuel supply to the engine via said stop member;

(iii) a normally open second valve means which opens to introduce the atmospheric pressure into said actuator so that said control member mediates a decreased amount of fuel supply to the engine via said stop member;

(iv) a control means which selectively closes or opens said first and second valve means such that the engine idling speed approaches the target idling speed, the target idling speed being set according to the engine operating conditions, and

(d) a normally closed third valve means which is opened or closed by said control means in place of said second valve means when the engine idling speed does not settle to the target idling speed until a predetermined period of time has elapsed.

2. A system for controlling the idling speed of a vehicular engine, which comprises:

(a) an actuator having two chambers partitioned by a diaphragm and a stopper extending from the diaphragm and capable of engaging a control member, an angular position of which controls the amount of fuel injected by a fuel injection pump into the Diesel engine, said stopper moving within an angularly movable range of the control member according to the pressure within one chamber;

(b) a negative pressure source;

(c) a first electromagnetic valve, located within a first passage connecting said one chamber of said actuator to the negative pressure source, which normally closes said first passage;

(d) a second electromagnetic valve, located within a second passage branching from said first passage, which normally opens the second passage to expose said one chamber of said actuator to atmosphere;

(e) a first sensor means for detecting and signalling the actual engine speed;

(f) a second sensor means for detecting and signalling an engine operating condition when the engine is idling;

3. (g) a third sensor means for detecting and signalling an engine load;

(h) control means which receives signals from said first, second and third sensor means and opens and closes said first and second electromagnetic valves selectively according to the engine operating condition detected by said second sensor means during engine idling as indicated by the signal from said third sensor means so that said stopper moves the engaged control member to control the amount of fuel injected to the engine to make the engine idling speed approach a target idling speed, and

(i) a third auxiliary electromagnetic valve normally closing a third passage opening to the atmosphere and branching from said second passage and wherein said control means actuates said third electromagnetic valve in place of said second electromagnetic valve when the engine idling speed remains higher than the target idling speed for a predetermined period of time.

9. The system according to claim 3, wherein said stop member disengages from said control member and is displaced to at least the first position by said third means when the engine operation is transferred from engine idle to a normal operation.

10. The system according to claim 3, wherein said third means comprises:

(a) a pressure-responsive actuator linked with said stop member which actuates said stop member according to pressure introduced thereinto;

(b) a vacuum pressure source;

(c) a normally closed first electromagnetic valve which opens to introduce vacuum pressure from said vacuum pressure source into said actuator so that said stop member is displaced to the first position when the first signal is received from said second means and which is closed when said second electrical signal is output by said second means;

(d) a normally open second electromagnetic valve which closes to prevent atmospheric pressure from entering into said actuator when the first signal is received from said second means and which is open to introduce atmospheric pressure into said actuator when said second electrical signal is output by said second means.

11. The system according to claim 9, which further comprises:

a third electromagnetic valve which is closed when said second electrical signal is output by said second means and which is open to introduce atmospheric pressure into said actuator in place of said second electromagnetic valve when a third signal for introducing atmospheric pressure into said actuator is received from said second means, the third signal being produced so as to decrease the engine idling speed when the idling speed exceeds the target engine idling speed and when a predetermined time has passed and said second electromagnetic valve remains closed.

12. The system according to claim 9, wherein said second means outputs the first signal only to said second electromagnetic valve to close the second valve when the idling speed matches with the target idling speed.

13. The system according to claim 9, wherein said second means sets first period of time for which said first electromagnetic valve is open and said second valve is closed according to a settling time for which the pressure in said actuator settles at the vacuum pressure from said vacuum source.

14. The system according to claim 12, wherein said second means sets a second period of time for which said second electromagnetic valve is open and said first valve is closed according to a settling time for which the pressure in said actuator settles at atmospheric pressure.

15. The system according to claim 13, wherein said second means sets the first period of time not to coincide with the second period of time and further sets said first and second periods of times to have no integral multiplicative relationship with each other.

17. A system as recited in claim 9, wherein said first and second electromagnetic valves are each operable only in opened and closed conditions.

18. A system as recited in claim 9, wherein said second means is operable for controlling a minimum idle position of said stop member by varying time durations in which said first and second electromagnetic valves are opened and closed.

4. A system for controlling an idle engine speed of a Diesel engine, comprising:

(a) a control member, an angular position of which controls an amount of fuel injected from a fuel injection pump to the engine;

(b) a stop member engaging said control member during engine idling within a predetermined angular displacement range of said control member, for regulating the amount of fuel injected to the engine by said control member during engine idling, said stop member assuring a minimum amount of fuel supply to the engine via said control member during engine start-up;

(c) first means for detecting engine idling operating conditions including engine idling speed;

(d) second means for calculating a target engine idling speed on the basis of the engine idling operating conditions and outputting a first electrical signal when the engine idling speed is below the target engine idling speed and outputting a second electrical signal when the engine idling speed exceeds the target engine idling speed; and

(e) third means for selectively adjusting a position of said stop member within the predetermined angular range of said control member during engine idling so that the engine idling speed approaches the target idling speed, said third means producing and introducing a vacuum pressure to displace said stop member to a first position, to increase the engine idling speed in response to the first electrical signal from said second means and said third means being so arranged as to introduce atmospheric pressure to displace said stop member to a second position to decrease the engine idling speed when said second electrical signal is output by said second means.

16. The method of claim 4 comprising further steps of opening and closing an auxiliary valve means to connect and disconnect an auxiliary passageway to said first means when it is determined that one of said electromagnetic valves is inoperable.

5. A method for controlling an idling speed of a Diesel engine, comprising the steps of:

(a) measuring an engine speed and engine load;

(b) determining whether the engine is idling on the basis of the engine load;

(c) measuring engine operating parameters other than the engine load;

(d) deriving a target engine idling speed on the basis of the measured engine parameters at which the engine will be able to idle smoothly without excessive fuel consumption;

(e) matching the engine speed with the target engine idling speed;

(f) providing first means for displacing a control element having a position which determines an amount of fuel supply to the engine in first and second directions to increase and decrease the fuel supply to the engine, respectively, according to air pressure exerted thereon;

(g) providing at least two electromagnetic valves, one of said electromagnetic valves being normally open to send atmospheric pressure to said first means so that the control element is displaced in the second direction with another of said electromagnetic valves closed, and the other electromagnetic valve being normally closed and being opened to send a vacuum pressure to said first means so that the control element is displaced in the first direction with the one electromagnetic valve closed; and

(h) limiting the displacment of the control element at a minimum fuel supply position through the normally open one electromagnetic valve when the engine speed does not match with the target engine idling speed for a predetermined period of time.

7. A system as recited in claim 5 further comprising means for compensating for failure of one of said electromagnetic valve means connected to one of said first and second pressures.

6. A system for controlling an idle engine speed of an engine comprising:

(a) a control means for controlling an amount of fuel supplied to the engine in accordance with a position thereof,

(b) a stop means engaging said control means during engine idling for determining a minimum amount of fuel to be supplied to the engine during engine idle,

(c) pneumatic control means for displacing said stop means in first and second directions respectively to increase and decrease the minimum amount of fuel to be provided to the engine during an idle condition,

(d) at least first and second open-close electromagnetic valve means for providing first and second pressures to said pneumatic control means,

(e) said first electromagnetic valve means normally open to provide atmospheric pressure to said pneumatic control means so that the stop means is displaced in the second direction with said second electromagnetic valve means closed, and said second electromagnetic valve means being normally closed and being opened to send a vacuum pressure to said pneumatic control means so that said stop means is displaced in the first direction with said first electromagnetic valve means closed, and

(f) system control means for controlling open and close times of said first and second electromagnetic valve means in response to predetermined engine conditions thereby to control the minimum amount of fuel provided to the engine during an idle condition, and

(g) limiting means for limiting the displacement of said stop means at a minimum fuel supply position through said normally open first electromagnetic valve means when the engine speed does not match with a target engine idling speed for a predetermined period of time.

8. A system as recited in claim 6, wherein said means for compensating comprises auxiliary electromagnetic valve means, connected to said one of said first and second pressures, for supplying said one pressure to said pneumatic control means when it is determined that said one electromagnetic valve means connected to said pressure is in a failed state.