JP5884589B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control device for a four-cycle engine.

  The 4-cycle engine has a configuration in which the crankshaft makes one rotation in two steps of intake and compression, and the crankshaft makes one rotation in the subsequent two steps of explosion and exhaust. Such ignition of a four-cycle engine is usually performed near the end (top dead center) of the compression stroke in which the piston moves up in the cylinder. On the other hand, even at the same ascending process, ignition at the end of the exhaust process is unnecessary.

  For example, Patent Document 1 discloses a method for eliminating the occurrence of unnecessary ignition (referred to as a fire or backfire) in the exhaust process. In the method described in Patent Document 1, in a four-cycle engine that generates an ignition pulse signal, the pulse widths of two successive ignition pulse signals are compared, and rotation with a relatively long pulse width is used as a compression stroke. Rotation with a short pulse width is discriminated from the exhaust process, and the occurrence of backfire in the exhaust process is eliminated.

JP 2000-282945 A

  By the way, when the conventional backfire elimination method is applied to an engine having a plurality of cylinders, the occurrence of backfire is eliminated by the following procedure.

  That is, (1) the engine process is determined only when a predetermined throttle opening and a predetermined intake pressure are obtained. (2) The compression stroke and the exhaust process are determined by comparing the pulse widths of the ignition pulse signals of two rotations in which the arbitrary rotation and the previous rotation continue. (3) The determination of (2) is performed a plurality of times, and the engine process is determined when the results are all the same. (4) The backfire for one cylinder is abolished based on the engine process determined in (3). (5) If there is no abnormality after performing (4), the backfire of the other cylinders will be abolished.

  Thus, in the conventional backfire abolition method, there are many determination procedures, and the engine process is determined only when the operating conditions are satisfied. Therefore, there is a problem that it takes a long time to abolish the backfire of all cylinders.

  In particular, in the case of an engine applied to a gas heat pump, the spark plug is replaced when the operation time reaches a certain time, but if the time until the end of the backfire is long, a lot of useless ignition is performed. On the other hand, there is a risk that the spark plug will deteriorate more than expected, resulting in misfire and engine stall.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an engine control device that can distinguish between normal ignition and backfire in a short time.

The invention according to claim 1, which has been made to achieve the above object, is a rectangular wave signal generating means for generating a rectangular wave signal synchronized with rotation of a crankshaft of the engine in an engine control device of a four-cycle engine, Based on the pulse width that is the time from the rising edge of the rectangular wave signal to the next falling edge and the pulse period that is the time period from the rising edge of the rectangular wave signal to the next rising edge in one cranking rotation of the engine. Control means for discriminating between the compression process and the exhaust process, and the rectangular wave signal generation means comprises: a rotor fixed to the crankshaft; a pulse generator for generating a pulse signal from the rotor; A waveform shaping circuit that generates the rectangular wave signal from the pulse signal generated by a pulse generator, and the rotor is on the outer peripheral portion, The control means includes the pulse width of the immediately preceding rectangular wave signal without using an integration operation. Backfire determination calculation calculated based on a plurality of consecutive pulse periods including a reference position determination calculation value Fn calculated based on a plurality of continuous pulse widths and the pulse period of the immediately preceding rectangular wave signal. Based on the value Bn, the compression process and the exhaust process are identified .

The front Symbol control means, before cranking during firing of the engine (ignition), or I-line identification of the compression process and the exhausting process.

The front Symbol control means, in cranking 1 in rotation of the engine, and the pulse width of the rectangular wave signal, based on said pulse period at least four successive said rectangular wave signal, and the compression process exhaust the identification of the process may be I line.

  According to the first aspect of the present invention, since the compression process and the exhaust process can be distinguished within one rotation of the cranking of the engine, it is possible to distinguish between normal ignition and backfire in a short time. . Also, the compression process and the exhaust process are identified based on the pulse width, which is the time from the rise of the rectangular wave signal to the next fall, and the pulse period, which is the time from the rise of the rectangular wave signal to the next rise. By doing so, the engine process determination and the backfire determination can be performed at the same timing, so the time until the backfire is abolished can be shortened.

Further, according to the invention described in claim 3 , since it is possible to discriminate between normal ignition and backfire at the time of cranking before starting the engine, it is possible to eliminate the occurrence of backfire. For this reason, misfire and engine stall can be suppressed.

In addition, the control means is configured to identify the compression process and the exhaust process based on the pulse width of the rectangular wave signal and the pulse period of at least four continuous rectangular wave signals within one cranking rotation of the engine. According, the pulse width of the rectangular wave signal, based on the pulse period in at least four successive square wave signal, since the identification of the compression process and exhaust process, to determine the ignition and the back fire regular more reliably It becomes possible.

It is explanatory drawing of the 3 cylinder 4 cycle engine which concerns on embodiment of this invention. It is explanatory drawing which shows the detail of a rotor. It is a figure which shows the pulse signal waveform which generate | occur | produces with a pulse generator, and the rectangular waveform shape | molded by the waveform shaping circuit. It is a flowchart which shows the flow of the backfire abolition control which CPU of an engine control apparatus performs according to the control program stored in ROM etc. FIG. It is explanatory drawing for demonstrating the calculation method of the calculation value Fn for reference position determination. It is explanatory drawing for demonstrating the calculation method of the calculation value Bn for backfire determination. It is a characteristic view which shows the relationship between cranking time and crank angle rise time (pulse period).

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the engine control device of the present invention is applied to a three-cylinder four-cycle engine of a gas heat pump.

  The three-cylinder four-cycle engine has three cylinders of a first cylinder, a second cylinder, and a third cylinder. In FIG. 1, only the first cylinder is illustrated, and the second cylinder and the third cylinder are illustrated. Is omitted.

  As shown in FIG. 1, a three-cylinder four-cycle engine 1 includes a spark plug 2, a valve 3, a piston 5 that reciprocates in the cylinder 4, and a crankshaft 10 that converts the reciprocating motion from the piston 5 into rotational motion. And a crank position sensor 6 as a rectangular wave signal generating means. The crank position sensor 6 includes a rotor 20 fixed to the crankshaft 10, one pulse generator 30 that generates a pulse signal from the rotor 20, and a waveform that generates a rectangular wave from the pulse signal generated by the pulse generator 30. And a shaping circuit 40. The sensor of the pulse generator 30 uses an electromagnetic induction method, and outputs a voltage by an electromagnetic induction action according to a change in magnetic flux due to the uneven shape of the rotor 20.

  As shown in FIG. 2, the rotor 20 includes five short teeth 21 fixed to the crankshaft 10 and one long tooth 22 having a circumferential length longer than the short teeth 21 at the outer peripheral portion.

  As shown in FIG. 3, when the crankshaft 10 rotates, the pulse generator 30 generates a positive voltage 32 when the short teeth 21 and long teeth 22 of the rotor 20 approach, and the rotor short teeth 21 and long teeth 22 A negative voltage 33 is generated when separated. The pulse signal waveform 31 is converted into a rectangular waveform 41 by the waveform shaping circuit 40. Long teeth and short teeth are discriminated from the period of the rectangular waveform 41 and the DUTY ratio.

  An engine control unit (ECU) 50 as a control means controls the operation of the spark plug 2 based on an input signal from the crank position sensor 6 and the like, and is a known microcomputer comprising a CPU, a ROM, a RAM, and the like. The peripheral circuit is used.

  Next, backfire abolition control of the engine control apparatus of this embodiment will be described based on FIG.

  The control flow of FIG. 4 starts before starting the four-cycle three-cylinder engine 1, that is, before firing during cranking. In the present embodiment, the operation is started 0.8 seconds after the starter (not shown) operates so that the backfire determination control can be performed with the crankshaft 10 rotating stably.

  First, in step S1, a reference position determination calculation value Fn is calculated. As shown in FIG. 5, the reference position determination calculation value Fn is a value calculated based on the time from the rising edge to the falling edge of the rectangular wave generated by the waveform shaping circuit 40, that is, the pulse width Tw. Although details will be described later, the engine process can be determined by comparing the reference position determination calculation value Fn with a predetermined determination value. The waveform shaping circuit 40 of the present embodiment forms a rising edge of a rectangular wave when the voltage output by the pulse generator 30 (sensor) becomes larger than a numerical value set in advance through experiments or the like, and generates a pulse after the rising edge. A fall is formed when the output voltage of the device 30 becomes smaller than a numerical value set in advance by experiments or the like. The pulse width Tw is obtained from the width of the rectangular waveform obtained above.

In the present embodiment, the reference position determination calculation value Fn is calculated by the following mathematical formula 1.
(Equation 1)
Fn = Tw _n-1 ² / (Tw _n-2 × Tw _n )
However, Tw _n is the pulse width Tw of the rectangular wave just _{before, Tw n-1} is set to the pulse width Tw of the rectangular wave of the previous _{Twn, Tw n-2} is the second preceding square wave pulse width Twn Let Tw.

If the pulse width _{Tw n-1} is longer than the pulse width Tw _n and the pulse width _{Tw n-2,} Fn is 6 or more. However, the numerical value (6) is a threshold value set in accordance with the present embodiment, and can be set to 1 or more, for example, and may be changed depending on the tooth shape of the rotor 20 or the like. Therefore, when Fn is 6 or more, it can be seen that Twn _-1 is the pulse width of the long teeth 22. In the present embodiment, either the compression process or the exhaust process is performed in the first cylinder during the time from the rising pulse of the long tooth 22 to the rising pulse of the next short tooth 21.

  In subsequent step S2, a backfire determination calculation value Bn is calculated. As shown in FIG. 6, the backfire determination calculation value Bn is a value calculated based on the time from the rising edge of the rectangular wave generated by the waveform shaping circuit 40 to the next rising edge, that is, the pulse period Rc. As will be described in detail later, by comparing the backfire determination calculation value Bn calculated in step S2 with a predetermined determination value, it is determined whether the compression process or the exhaust process, that is, the regular ignition timing or the backfire. Can do.

In the present embodiment, the backfire determination calculation value Bn is calculated by the following mathematical formula 2.
(Equation 2)
_{Bn = (Rc n-3 ×} Rc n-2) / (Rc n-1 × Rc n)
However, Rc _n is the pulse period Rc of the rectangular wave just before, _{Rc n-1} is the pulse period Rc of the rectangular wave of the previous one of Rc _{n, Rc n-2} is the square wave of the previous two Rc _n a pulse period Rc, _{Rc n-3} is the pulse period Rc of the rectangular wave of the previous three Rc _n.

  When the engine speed is constant, Bn is 1. However, in actuality, in the compression process, the gas in the cylinder 4 is compressed by the piston 5, so that the rotation of the crankshaft 10 becomes slow. In the exhaust process, since the valve 3 is open, there is no gas compression, and the rotation of the crankshaft 10 is faster than the compression process. That is, the pulse period Rc is increased in the compression process, and the pulse period Rc is decreased in the exhaust process.

Specifically, it has been found from the experimental study by the present inventor that the pulse period Rc in four continuous rectangular waves has a relationship as shown in the characteristic diagram of FIG. That is, when (30 ms before and after in this example) pulse period _{Rc n-3} and the pulse period _{Rc n-2} and is shorter in succession, a pulse period _{Rc n-1} and the pulse period Rc _n becomes longer continuously ( 40ms or more in this example). On the other hand, when the pulse period _{Rc n-3} and the pulse period _{Rc n-2} and a long continuous (or 40ms in this embodiment) is shorter and the pulse period _{Rc n-1} and the pulse period Rc _n is continuously ( (In this example, around 30 ms).

Using this characteristic, when Bn is less than 1, that is, the value obtained by multiplying a pulse period _{Rc n-1} and the pulse period Rc _n is multiplied by the pulse period _{Rc n-2} pulse period _{Rc n-3} value If it is larger than that, it can be determined that the process close to the present time is the compression process in which the rotation of the crankshaft 10 is slowed out of the compression process and exhaust process.

On the other hand, when Bn is 1 or more, i.e., a value obtained by multiplying a pulse period _{Rc n-1} and the pulse period Rc _n is equal to or less than a value obtained by multiplying a pulse period _{Rc n-3} and the pulse period _{Rc n-2} In this case, it can be determined that the process close to the present time is an exhaust process in which the rotation of the crankshaft 10 is faster than the compression process among the compression process and the exhaust process, and the backfire at this time is abolished.

In subsequent step S3, it is determined whether Bn is smaller than 1 and Fn is 6 or more.
Here, as described above, when Fn is larger than 1, as shown in FIG. 5, the pulse width Tw _n-1 of the immediately preceding rectangular wave P _{n-1 is} the pulse width of the immediately preceding rectangular wave Pn. has become longer state than Tw _n and second preceding square wave _{P n-2} of the pulse width _{Tw n-2.} That is, when Fn is larger than 1, the immediately preceding rectangular wave P _n is a rectangular wave next to the rectangular wave whose pulse width Tw is longer than the other rectangular waves, and the rising pulse of the previous rectangular wave P _n−1 . It can be determined that the compression process or the exhaust process is performed in the first cylinder during the period from the rising pulse of the rectangular wave P _n to the immediately preceding pulse.

In the present embodiment, it is determined that either the compression process or the exhaust process is performed in the first cylinder when Fn is 6 or more so that the error can be ignored.
When Bn is smaller than 1, as described above, it is determined that the determination target is the compression process of the compression process and the exhaust process, that is, the normal ignition timing.

Therefore, if it is determined in step S3 that Bn is smaller than 1 and Fn is 6 or more (Bn <1, Fn ≧ 6), it is determined that the compression process is performed in the first cylinder. Then, the process proceeds to step S4, the rising position of the rectangular wave Pn in the period of the pulse width Rc _n it is determined that the compression process, the value of the pulse counter is "11". Here, the pulse counter is a counter that is cyclically counted up between “0 to 11”. The state in which the value of the pulse counter has just been switched to any one of “5, 11” The timing when the piston 5 becomes top dead center is shown. That is, in the present embodiment, 11 is controlled as the ignition position of the first cylinder, and 5 as the backfire position of the first cylinder. The engine control unit 50 does not perform ignition in the first cylinder when the pulse counter is 5 (backfire position).

  On the other hand, if it is determined in step S3 that Bn is smaller than 1 and Fn is not 6 or more, the process proceeds to step S5. In step S5, it is determined whether Bn is 1 or more and Fn is 6 or more. As described above, when Fn is 6 or more, it can be determined that either the compression process or the exhaust process is performed in the first cylinder. When Bn is 1 or more, it is determined that the determination target is the exhaust process of the compression process and the exhaust process, that is, the timing of the backfire.

Thus, at step S5, if Bn is determined to be in it and Fn is 6 or more 1 or more (Bn ≧ 1, Fn ≧ 6), the exhaust process is performed in the period Rc _n in the first cylinder In step S6, the value of the pulse counter is set to “5”, and the backfire is abolished based on the pulse counter.

  On the other hand, if it is determined in step S5 that Bn is not less than 1 and Fn is not not less than 6, the process returns to step S1.

  According to this embodiment, since the backfire determination can be performed within one cranking rotation, it is possible to distinguish between normal ignition and backfire in a short time. Furthermore, as shown in the above control flow, the engine process determination (steps S1, S3 to S6) and the backfire determination (steps S2, S3 to S6) can be performed at the same timing, so the backfire is abolished. The time until it can be shortened. Moreover, since the start time of a starter can be shortened by shortening the time required for backfire determination, it is possible to suppress deterioration of starter components.

  Further, by performing the backfire determination control before starting the four-cycle three-cylinder engine 1, that is, before firing at the time of cranking, it is possible to prevent backfire from occurring at all. Thereby, generation | occurrence | production of misfire and engine stall can be suppressed. In particular, in the case of an engine for a gas heat pump in which the spark plug is replaced when the operation time reaches a certain time, it is possible to avoid a state in which the spark plug is deteriorated more than expected with respect to the operation time, so that there is a great practical advantage. It is.

  Further, by performing the backfire determination control before starting the four-cycle three-cylinder engine 1, the occurrence of engine stall can be suppressed even when the determination fails.

(Other embodiments)
In the above-described embodiment, the example in which the engine control device of the present invention is applied to a gas heat pump engine has been described.

  Moreover, although the example which employ | adopted the 3 cylinder engine as an engine was demonstrated in the said embodiment, not only this but a single cylinder engine may be employ | adopted and an engine of 2 cylinders or 4 cylinders or more may be employ | adopted. Good.

  The threshold value of Fn (6 in the present embodiment) may be other than the above. The threshold value can be set according to the engine by experiment. Moreover, the arithmetic expressions of Fn and Bn are not limited to the above. The arithmetic expression of Fn only needs to determine that the discrimination target (period) is the compression process or the exhaust process among the four cycles, and the arithmetic expression of Bn is whether or not the discrimination target (period) is the compression process (or What is necessary is just to determine whether it is an exhaust process or not. However, the process determination can be performed more reliably by using the characteristics shown in FIG.

  Moreover, the execution order of step S1 and step S2 may be simultaneous or reverse. Similarly, the execution order of step S3 and step S5 may be simultaneous or opposite. Since one crankshaft 10 is commonly used for each cylinder, if ignition / backfire in the first cylinder can be determined, ignition / backfire in other cylinders can also be determined.

1: Engine, 6: Crank position sensor (rectangular wave signal generating means),
10: Crankshaft 50: Engine control unit (control means)

Claims (3)

An engine control device for a four-cycle engine,
Rectangular wave signal generating means for generating a rectangular wave signal synchronized with the rotation of the crankshaft of the engine;
Based on the pulse width that is the time from the rising edge of the rectangular wave signal to the next falling edge and the pulse period that is the time period from the rising edge of the rectangular wave signal to the next rising edge in one cranking rotation of the engine. Control means for distinguishing between the compression process and the exhaust process ;
With
The rectangular wave signal generating means generates a rectangular wave signal from the rotor fixed to the crankshaft, a pulse generator that generates a pulse signal from the rotor, and the pulse signal generated by the pulse generator. A waveform shaping circuit,
The rotor has a plurality of short teeth and a long tooth having a larger circumferential length than the short teeth on an outer peripheral portion;
The control means does not use an integration calculation, and calculates a reference position determination calculation value Fn calculated based on a plurality of continuous pulse widths including the pulse width of the immediately preceding rectangular wave signal, and the immediately preceding rectangular wave signal. An engine control device that identifies the compression process and the exhaust process based on a backfire determination calculation value Bn calculated based on a plurality of successive pulse periods including the pulse period . The reference position determination calculation value Fn is:
Fn = Tw _n-1 ² / (Tw _n-2 × Tw _n )
Calculated by
  Tw _n Is the pulse width of the previous rectangular wave signal and Tw _n-1 Is Tw _n The pulse width of the rectangular wave signal immediately before _n-2 Is Tw _n The pulse width of the rectangular wave signal two times before
  The backfire determination calculation value Bn is:
Bn = (Rc _n-3 × Rc _n-2 ) / (Rc _n-1 × Rc _n )
Calculated by
  Rc _n Is the pulse period of the immediately preceding rectangular wave signal, and Rc _n-1 Is Rc _n Rc is the pulse period of the rectangular wave signal one before, Rc _n-2 Is Rc _n The pulse period of the rectangular wave signal two times before _n-3 Is Rc _n The pulse period of the rectangular wave signal three times before
  The control means determines that the exhaust process is performed when it is determined that the backfire determination calculation value Bn is 1 or more and the reference position determination calculation value Fn is a predetermined value or more. The engine control device according to claim 1, wherein the engine control device is abolished. Wherein, prior to firing of the cranking of the engine, the engine control apparatus according to claim 1 or 2 and identifies the compression step and the evacuation step.

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