Title of Invention

APPARATUS FOR CONTROLLING IGNITION TIMING OF ENGINE

Abstract

To provide an apparatus for controlling ignition timing of an engine, capable of preventing occurrence of back fire by a simple configuration. An apparatus for controlling ignition timing of an engine, for variably controlling ignition timing of an engine in accordance with operating conditions, including: no-load deceleration state detecting means 104 for detecting that an engine is in a no-load deceleration state; engine speed detecting means 22 for detecting engine speed; an advanced timing setting unit 102 for setting an advanced ignition timing (retard amount) in environments where probability of occurrence of back fire is high (no-load deceleration state), and a converter 105 for determining an ignition angle θig on the basis of an output pulse of a pulse generator 24 and an advance amount notified from the advanced ignition timing setting unit 102.

Full Text

FORM 2 THE PATENTS ACT 1970 [39 OF 1970] COMPLETE SPECIFICATION [See Section 10] "APPARATUS FOR CONTROLLING IGNITION TIMING OF ENGINE" HONDA GIKEN KOGYO KABUSHIKI KAISHA, a corporation of Japan, having a place of business at 1-1, Mmamiaoyama 2-chome, Minato-ku, Tokyo, Japan, The following specification particularly describes the nature of the invention and the manner in which it is to be performed:- The present invention relates to apparatus for controlling ignition timing of engine. [0001] [Technical Field of the Invention] The present invention relates to an apparatus for controlling ignition timirifir of an engine and, more particularly, to an apparatus for controling ignition timing of an engine -, capable of preventing occurrence of back fire by a simple configuration. [0002] [Prior Art] When engine speed is decreased sharply, the ratio of fresh air to the volume of a cylinder is lowered and charging efficiency decreases, so that the air-fuel ratio in the cylinder becomes lean. Due to this, there is the possibility that what is called a back, fire phenomenon such that flame propagating speed becomes slow and flame spreads into an intake path occurs. [0003] -In order...to preven.such a. back fire phenomenon, for example, in Japanese Patent Bulletin No. 2,646,216, at the time of sudden deceleration, an ignition timing control for advancing the ignition timing more than ignition timing in normal time until a throttle is fully closed is performed. [0004] [Problems to be solved by the Invention] In the conventional technique, the ignition timing is 2 advanced more than that in the normal time until the throttle is fully closed at the time of sudden deceleration. After the throttle is fully closed, the ignition timing is reset to the standard ignition timing in the normal time. However, according to the result of experiments conducted by the inventors, back fire occurs the most in a sudden deceleration state, particularly, when the throttle is suddenly opened from a no-load deceleration state. Therefore, when the ignition timing is reset from the advanced state to the normal state at the time point the throttle is fully closed as in the conventional technique, back fire cannot be effectively prevented. [0005] On the other hand, when the ignition timing is advanced after the throttle opening operation is detected at the time of sudden deceleration, the flame propagation speed just before the opening operation cannot be improved. When the ignition timing is advanced only on condition that the throttle is fully closed, a problem such that drivability deteriorates due to an increase in the frequency of occurrence of knocking newly occurs. [0006] An object of the invention is to solve the problems of the conventional technique and to provide an apparatus for controlling ignition timing of an engine, capable of effectively preventing back fire by a simple configuration. [Means for solving the Problems] [0007] 3 In order to achieve the object, the invention is characterized in that an apparatus for controlling ignition timing of an engine, for variably controlling ignition timing of an engine in accordance with operating conditions is provided with the following means. [0008] (1) The apparatus is characterized by including: no-load deceleration state detecting means for detecting that an engine is in a no-load deceleration state; engine speed detecting means for detecting engine speed; and advancing means for making ignition timing advance more than a standard ignition angle when the engine speed is in a predetermined low speed range in the no-load deceleration state. [0009] (2) The apparatus further includes throttle position detecting means for detecting a throttle position, and is characterized in that the no-load deceleration state detecting means determines that the engine is in the no-load deceleration state when a drop rate of the engine speed is higher than a predetermined reference drop rate and the throttle position is full close position. [0010] (3) The apparatus is characterized in that the no-load deceleration state detecting means determines that the engine is in the no-load deceleration state when a drop rate of the engine speed is higher than a predetermined reference drop rate. [0011] 4 According to the characteristic (1) , the ignition timing is advanced at the time of throttle sudden opening from the no-load deceleration state, which is the timing when back fire occurs the most. As a result, combustion can be finished in a cylinder before an exhaust port is opened, so that occurrence of back fire can be prevented without deteriorating drivability. [0012] According to the characteristic (2) , whether the engine is in the no-load deceleration state or not is determined on the basis of throttle angle and engine speed. Thus, detecting means for detecting that the engine and the output shaft are disengaged from each other is unnecessary. [0013] According to-the characteristic (3), by using the fact that the drop rate of the engine speed at the time of no-load deceleration is peculiar to each engine, whether the engine is in the no-load deceleration state or not is determined on the basis of only the engine speed. Thus, detecting means for detecting that the engine and the output shaft are disengaged from each other and means for detecting throttle angle are unnecessary. 5 [Brief Description of the Drawings] FIG. 1 is a block diagram showing the configuration of main components of an ignition timing control apparatus to which the invention is applied. FIG. 2 is a flowchart for explaining operations of FIG. 1- FIG. 3 is a timing chart for explaining the operations Of FIG. 1. [0014] [Mode for carrying out the Invention] The present invention will be described in detail hereinbelow with reference to the drawings. FIG. 1 is a block diagram showing the configuration of main components of an ignition timing control apparatus to which the invention is applied. [0015] A coolant temperature sensor 21 senses temperature Teng of cooling water of the engine. An Ne sensor 22 senses an engine speed Ne. A throttle position sensor 2 3 senses a throttle angle 0th. A pulse generator 24 generates a pulse signal representing a crank angle of the engine. [0016] An ignition control unit 10 calculates an ignition timing on the basis of the cooling water temperature Tengi engine speed Ne, throttle angle 0th, and pulse generation timing of the pulse generator 24, and supplies arc energy to an ignition plug 26 via an ignition coil 25. [0017] In the ignition control unit 10, a standard ignition timing setting unit 101 sets a standard ignition timing (advance amount or retard amount) on the basis of the cooling water temperature Teng, engine speed Ne, and throttle angle 0th. An advance angle timing setting unit 102 sets an advance ignition timing (retard angle) in environments where the occurrence probability of back fire (no-load deceleration state in the embodiment) is high on the basis of the cooling water temperature Teng» engine speed Ne, and throttle angle 0th. The advance amount is set to be larger than the advance amount selected by the standard ignition timing in the case where the engine is not in the no-load deceleration state. [0018] A AN detecting unit 103 detects a rate AN of change in engine speed. A no-load deceleration state determining unit 104 determines whether or not the engine is in the no-load deceleration state in which the engine and the output shaft are disengaged from each other, that is, whether or not a clutch is disengaged or a gear position is neutral and the throttle is closed on the basis of the engine speed Ne, throttle angle 0th, and rate AN of change in engine speed. When the engine is in the no-load deceleration state, a switching unit 106 is controlled to connect the advanced ignition timing setting unit 102 and a converter 105. When the engine is not in the no-load deceleration state, the standard ignition timing setting unit 101 and the converter 105 are connected to each other. [0019] The converter 105 determines an ignition angle 6ig on the basis of the output pulse of the pulse generator 24 and the advance amount or retard amount notified from the standard ignition timing setting unit 101 or the advanced ignition timing setting unit 102. The arc energy supplied to the ignition coil 25 is interrupted at the ignition angle 0ig, thereby allowing the ignition plug 26 to make ignition at an optimum timing. [0020] Next, by referring to the flowchart of FIG. 2 and the timing chart of FIG. 3, the operation of the ignition control unit 10 will be described. The flowchart of FIG. 2 shows mainly processes in the no-load deceleration state determining unit 104. [0021] In step S10, on the basis of an output signal of the throttle position sensor 23, whether the throttle is in a full close state or not is determined. When the throttle is not in the full close state like at time tO in FIG. 3, it is determined that the engine is not in the no-load deceleration state and, therefore, back fire is not prone to occur, and the program advances to step S13. [0022] In step S13, the switching unit 106 is controlled so that the standard ignition timing setting unit 101 and the converter 105 are connected to each other. As a result, in the ignition control unit 10; the ignition angle 0ig is calculated on the basis of the standard ignition timing set by the standard ignition timing setting unit 101 and a detection timing of the pulse signal, and normal ignition of allowing the plug 26 to make ignition at the ignition angle 0ig is executed. [0023] On the other hand, when the throttle is fully closed at time tl in FIG. 3 and the full close state is detected in step S10, in step Sll, whether the engine speed Ne detected by the Ne sensor 22 is within a predetermined control execution range or not is determined. In the embodiment, the control execution range is set to a low speed range from an idle speed (about 1000 rpm) to 3000 rpm. Consequently, for example, at time t2, when the engine speed Ne enters the control execution range, the program advances to step S12. [0024] In step S12, whether or not a drop rate AN of the engine speed Ne obtained by the AN detecting unit 103 is equal to or higher than a predetermined reference drop rate ANref is determined. In the embodiment, the reference drop rate ANref is set to 200rpm/100msec. When the drop rate AN of the engine speed Ne exceeds the reference drop rate ANref at time t3 and it is detected in step S12, in step S14, the switching unit 106 is controlled so that the advanced ignition timing setting unit 102 and the converter 105 are connected to each other. [0025] As a result, in the ignition control unit 10, the ignition angle 0ig is calculated on the basis of the advance amount set in the advance ignition timing setting unit 102 and the detection timing of the pulse signal, and the advancing control for allowing the plug 26 to make ignition at the ignition angle 6ig is executed. [0026] According to the embodiment, when the no-load deceleration state where back fire is most prone to occur is detected and the engine speed is in the low speed range, the ignition timing is advanced more than that in normal time (expressed by a dotted line in the drawing) . Therefore, even when the throttle is suddenly opened from the no-load deceleration state at time t4, back fire is not prone to occur. [0027] Further, in the embodiment, whether the engine is in the no-load deceleration state or not is determined on the basis of the throttle angle and the engine speed without detecting that the engine and the output shaft are disengaged from each other. Consequently, a sensor for sensing that the gear is in the neutral position, a sensor for sensing that the clutch is disengaged, and the like are unnecessary. [0028] According to the result of the experiments conducted by the inventor, the drop rate of the engine speed at the time of the no-load deceleration is peculiar to each engine. Whether the engine is in the no-load deceleration state or not can be therefore determined on the basis of only the drop rate of the engine speed. With such a configuration, not only the sensor for sensing that the engine and the output shaft are disengaged from each other but also the throttle position sensor become unnecessary. [0029] [Effects of the Invention] According to the invention, effects as described hereinbelow can be achieved. [0030] (1) Since the no-load deceleration state where back fire is most prone to occur is detected and the ignition timing is advanced, even when the throttle is suddenly opened after that, occurrence of back fire can be effectively prevented. [0031] (2) Whether the engine is in the no-load deceleration state or not is determined on the basis of the throttle angle and the engine speed, so that a sensor for sensing that the engine and the output shaft are disengaged from each other, that is, a sensor for sensing that the clutch is disengaged or the gear is in the neutral position are unnecessary. [0032] (3) By using the fact that the drop rate of the engine speed at the time of the no-load deceleration is peculiar to each engine, whether the engine is in the no-load deceleration state or not is determined on the basis of only the engine speed. Thus, not only the sensor for sensing that the engine and the output shaft are disengaged from each other but also the throttle position sensor become unnecessary. claim: 1. An apparatus for controlling ignition timing of an engine, for variably controlling ignition timing of an engine in accordance with operating conditions, characterized by comprising: no-load deceleration state detecting means for detecting that an engine is in a no-load deceleration state; engine speed detecting means for detecting engine speed; and advancing means for making ignition timing advance more than a standard ignition angle when the engine speed is in a predetermined low speed range in the no-load deceleration state. 2. The apparatus for controlling ignition timing of an engine as claimed in claim 1, further comprising throttle position detecting means for detecting a throttle position, wherein said no-load deceleration state detecting means determines that the engine is in the no-load deceleration state when a drop rate of the engine speed is higher than a predetermined reference drop rate and the throttle position is full close position. 3. The apparatus for controlling ignition timing of an engine as claimed in claim 1 wherein said no-load deceleration state detecting means determines that the engine is in the no-load deceleration state when a drop rate of the engine speed is higher than a predetermined reference drop rate. 4. An apparatus for controlling ignition timing of an engine substantially as herein described with reference to the accompanying drawings. Dated this 27/11/2001 [RITUSHKA NEGI] OF REMFY & SAGAR ATTORNEY FOR THE APPLICANTS

Documents:

1134-mum-2001-abstract(11-05-2007).doc

1134-mum-2001-abstract(11-05-2007).pdf

1134-mum-2001-cancelled pages(11-05-2007).pdf

1134-mum-2001-claim(granted)-(11-05-2007).doc

1134-mum-2001-claim(granted)-(11-05-2007).pdf

1134-mum-2001-correspondence(11-05-2007).pdf

1134-mum-2001-correspondence(ipo)-(15-01-2007).pdf

1134-mum-2001-drawing(11-05-2007).pdf

1134-mum-2001-form 1(11-05-2007).pdf

1134-mum-2001-form 1(27-11-2001).pdf

1134-mum-2001-form 18(16-11-2005).pdf

1134-mum-2001-form 2(granted)-(11-05-2007).doc

1134-mum-2001-form 2(granted)-(11-05-2007).pdf

1134-mum-2001-form 3(01-04-2002).pdf

1134-mum-2001-form 3(11-05-2007).pdf

1134-mum-2001-form 3(27-11-2001).pdf

1134-mum-2001-form 5(27-11-2001).pdf

1134-mum-2001-petition under rule 137(10-05-2007).pdf

1134-mum-2001-petition under rule 138(10-05-2007).pdf

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