JP3289655B2 - Rotation direction switching control method for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the rotation direction of an internal combustion engine for switching the rotation direction of a spark ignition type reciprocating piston type internal combustion engine.

[0002]

2. Description of the Related Art A small two-stroke internal combustion engine or a four-stroke internal combustion engine is used as a drive source in a vehicle such as a scooter or a snowmobile that emphasizes simplicity. 2. Description of the Related Art Centrifugal clutch type continuously variable transmissions are often used as power transmission devices for transmitting output to drive wheels. This type of vehicle is small, lightweight,
In order to emphasize low cost, as a continuously variable transmission,
Often a gear without a built-in backgear is used.

[0003] As described above, in a vehicle or the like using a transmission that does not have a reverse gear, it is not possible to reverse, so when it is necessary to reverse the running direction in a narrow place, the vehicle It was necessary to lift the entire body and change its direction, and the operability was poor.

[0004] As described above, in order to reverse the running direction of a vehicle not provided with a reverse gear, the rotation direction of the internal combustion engine may be switched when necessary.

As a method for switching the rotation direction of an internal combustion engine, a method described in the specification and drawings of US Pat. No. 3,036,802 has been proposed. In the proposed method, when it is necessary to switch the rotation direction of the engine, the operation of the ignition device is stopped to cause the engine to misfire, thereby reducing the rotation speed of the crankshaft of the engine, thereby reducing the crankshaft speed. When the rotation speed of the engine is reduced to the set value and the vehicle is about to stop, the ignition operation is performed at a sufficiently advanced rotation angle position to push back the piston to reverse the rotation direction of the engine. After reversing the rotation direction of the engine in this way, the engine is immediately changed in the ignition position to a rotation angle position suitable for maintaining the rotation in the reversed direction, and the engine in the state where the rotation direction is reversed. Continue driving.

[0006]

SUMMARY OF THE INVENTION US Patent No. 3,033
In the proposed method disclosed in U.S. Pat. No. 6,802,802, the engine is misfired when the rotation speed of the engine is reduced. Therefore, when the rotation direction of the engine is reversed, a large amount of unburned gas (particularly, HC component) is generated. There was a problem of emission and polluting the atmosphere.

Further, in the proposed method, when reversing the rotation direction of the engine, the ignition operation is restarted in a state where unburned exhaust gas is accumulated in the exhaust pipe, so that the unburned gas is ignited in the exhaust pipe. Afterfire was generated, and a loud explosion sound was generated at that time, which could cause anxiety to the driver, or the engine body and the exhaust pipe might be damaged by an impact generated when the afterfire was generated.

It is an object of the present invention to propose a method for switching the rotation direction of an internal combustion engine, which is capable of reversing the rotation direction of a crankshaft without discharging unburned gas.

[0009]

SUMMARY OF THE INVENTION The present invention provides a spark igniter that is ignited by an igniter having a piston reciprocating in a cylinder and a crankshaft connected to the piston and capable of controlling an ignition position. The present invention relates to a method of switching the rotation direction of a reciprocating piston type internal combustion engine.

In the present invention, a rotation direction detecting means for detecting the rotation direction of the internal combustion engine is provided, and when a reversal command for reversing the rotation direction of the internal combustion engine is given, the throttle valve is opened. The ignition position of the internal combustion engine is gradually advanced to the over-advanced side while the degree is kept close to the opening at the time of idling, and the rotation direction of the internal combustion engine is reversed by the over-advanced angle of the ignition position. When the direction detecting means detects that the rotation direction of the internal combustion engine has been reversed, the ignition position of the engine is shifted to a rotation angle position suitable for maintaining the rotation of the internal combustion engine in the reversed direction.

[0011] The ignition position of the internal combustion engine is represented by the rotational angle position of the crankshaft of the engine. The ignition position of the engine is changed (advanced) to a position side ahead of the top dead center (the rotation angle position of the crankshaft when the piston reaches the top dead center) according to the operating condition of the engine. The ignition position at each rotation speed during steady operation is set to a position required to extract a predetermined output from the engine and to stably rotate the engine.

In the present invention, "over-advancement" of the ignition position means that the ignition position is advanced further than the proper ignition position at each rotational speed during steady operation.

As described above, when the ignition position of the internal combustion engine is gradually advanced to the over-advanced side, the position where the pressure in the cylinder becomes maximum after ignition shifts to the advanced side, and the ignition position As the force for pushing back the piston increases with the advance of the engine, the rotational speed of the engine gradually decreases. When the ignition position is advanced to a certain point, the engine reverses because the force trying to push back the piston overcomes the force of the piston trying to rise toward top dead center. When it is detected that the rotation direction of the engine is reversed, the ignition position is shifted to a rotation angle position suitable for maintaining the rotation of the internal combustion engine (for example, a position near top dead center). Thus, the rotation of the internal combustion engine in the reverse direction can be maintained.

According to the above-described method, the rotation direction of the internal combustion engine can be reversed without causing any misfire, so that unburned gas is prevented from being discharged when the rotation direction of the engine is switched. Thus, it is possible to eliminate the possibility that afterfire is generated at the time of switching the rotation direction or the atmosphere is polluted.

In the present invention, when the reversal command is given, the ignition position of the internal combustion engine is gradually increased toward the over-advance angle side while the opening of the throttle valve is kept close to the opening during idling. A first over-advance process in which the rotational speed of the internal combustion engine is reduced by advancing the engine; and a final over-advance process in which the ignition position is set when the rotational speed of the internal combustion engine has decreased to the set step over-advance start rotational speed. Performing a second over-advance angle process of advancing in a step-like manner to the advance position, and when the rotation direction detecting means detects that the rotation direction of the internal combustion engine has been reversed in the second over-advance angle process, The ignition position may be shifted to a rotation angle position suitable for maintaining the rotation of the internal combustion engine in the reverse direction.

As described above, the rotational speed at which the rotational direction of the engine is reliably reversed when the ignition position is over-advanced by a predetermined angle in a step-like manner is preset as a step over-advance angle start rotational speed. If the ignition position is over-advanced in a step-like manner when the rotation speed of the engine has decreased to the set step over-advance start rotation speed, the ignition position is changed to the final over-advance position where the rotation direction of the engine is reversed. Since the ignition position can be advanced to the final over-advanced position in a shorter time than in the case where the angle is gradually advanced, the reversal of the rotation direction of the engine can be performed in a shorter time. Further, since a period in which knocking occurs due to an excessive advance of the ignition position can be shortened, it is possible to prevent unnecessary impact on the engine when reversing the rotation direction of the engine.

In this case, the step over-advance start rotational speed is sufficiently set so that an impact generated when the ignition position is advanced step-wise to the final advance position can be limited to a range that does not cause any trouble. Set to a lower value.

When the internal combustion engine is determined, the relationship between the ignition position and the rotational speed of the engine is substantially determined. Therefore, the ignition position corresponding to the step over-advance start rotational speed can be obtained in advance. Therefore, this ignition position is set as a step over-advance angle start position, and the ignition position is set when the ignition position of the internal combustion engine has advanced to the set step over-advance angle start position. The rotation direction of the engine may be reversed by advancing in a step-like manner up to this point.

That is, in the present invention, when the reversal command is given, the ignition position of the internal combustion engine is gradually increased toward the over-advance angle side while the opening of the throttle valve is kept near the opening during idling. A first over-advance process in which the rotational speed of the internal combustion engine is reduced by advancing the internal combustion engine to a final step in which the ignition position is set when the ignition position of the internal combustion engine is advanced to a set step over-advance start position. A second over-advance angle process of step-advancing to the over-advance position is performed, and the rotation direction detecting means detects that the rotation direction of the internal combustion engine has been reversed during the second over-advance angle process. At times, the ignition position may be changed to a rotation angle position suitable for maintaining the rotation of the internal combustion engine in the reverse direction.

In the present invention, when the reversal command is given, the ignition position of the internal combustion engine is gradually shifted to the over-advanced side while the opening of the throttle valve is kept near the opening during idling. A first over-advance process in which the rotation speed of the internal combustion engine is reduced by advancing the engine, and when the rotation speed of the internal combustion engine decreases to a set step over-advance start rotation speed, or when the ignition position is step-advanced. A second advance for igniting at least one cylinder of the internal combustion engine at the final over-advanced position by advancing the ignition position to a set final over-advanced position when advanced to the angle start position; Angular process,
After the second over-advancing process is completed, the ignition position of each cylinder is shifted to the set ignition position set near the top dead center to determine whether or not the rotation direction of the engine is reversed. May be performed.

Since the rotation speed when the rotation of the engine is reversed is very low and unstable, it is detected that the rotation direction of the engine has been reversed with the ignition position advanced to the final over-advanced position. Although it is not always easy to perform, it is easy to determine the rotation direction of the engine by checking the rotation direction of the engine after returning the ignition position to near the top dead center as described above. it can.

In order to prevent the engine from stopping when reversing the direction of rotation of the engine, the ignition in the second over-advancing angle process is performed once in at least one cylinder or once in each cylinder. It is preferable to avoid performing ignition at the final over-advanced position more than once in each cylinder as much as possible.

In order to notify the driver that the engine has been reversed, when the rotation direction of the engine is detected to be reversed in the above-described rotation direction determination process, a display means for displaying that the rotation direction of the engine has been reversed is displayed. It is desirable to perform the operation.

In order to ensure that the rotation of the engine is reversed, when it is detected that the rotation direction of the engine has not been reversed in the rotation direction discrimination step, the rotation direction of the engine is checked until it is confirmed that the rotation direction of the engine has been reversed. A series of processes from the first over-advance angle process to the rotation direction discrimination process is repeated, and after it is detected in the rotation direction discrimination process that the rotation direction of the engine is reversed, the rotation direction is reversed. Preferably, the engine is operated.

In an internal combustion engine, the higher the temperature of the air-fuel mixture, the faster the propagation speed of the flame generated when the fuel is ignited, and the shorter the time until the explosive force applied to the piston after ignition reaches the maximum value. . Therefore, when the rotation direction of the engine is reversed by advancing in a step-like manner, and when the temperature of the air-fuel mixture at the time of reversing the engine is high, the advance amount when the ignition position is over-advanced in a step-like manner is reduced. be able to. Further, when the temperature of the air-fuel mixture is low, it is necessary to increase the amount of advance when the ignition position is over-advanced in a step-like manner.

Therefore, in the present invention, the ignition position is advanced in a step-like manner when the rotation speed of the engine is reduced to the rotation speed at which the step advance is advanced or when the ignition position is advanced to the start position at which the step advance is advanced. When the method of inverting the rotation direction of the engine by angling is adopted, at least one of an engine temperature sensor for detecting the temperature of the internal combustion engine and an intake air temperature sensor for detecting the intake air temperature of the internal combustion engine is provided. The final over-advance position is changed according to the temperature detected by the temperature sensor so that the advance amount when the ignition position is over-advanced in a step-like manner is increased as the temperature detected by the sensor is lower. Is preferred.

In the present invention, when the ignition position of the internal combustion engine is gradually advanced after the inversion command signal is given, the air-fuel mixture supplied to the internal combustion engine is maintained within a range where the internal combustion engine is not stopped. By changing the fuel ratio to the lean side or rich side, the output torque of the internal combustion engine is reduced,
It is preferable to suppress an impact generated when switching the rotation direction of the engine.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of the configuration of an internal combustion engine control device used for implementing a rotation direction switching method according to the present invention. In FIG. 1, reference numeral 1 denotes an internal combustion engine to be controlled. 2, a fuel injection valve (injector) for supplying fuel to the internal combustion engine 1; 3, a fuel pump for supplying fuel to the fuel injection valve 2; 4, a fuel injection control device for controlling the fuel injection valve; It is an ignition device for igniting. Also 6
Is a rotation sensor that detects the rotation of the internal combustion engine 1, 7 is a determination command generation unit that generates an inversion command, and 8 is an ignition device that reverses the rotation direction of the internal combustion engine when the inversion command generation unit generates an inversion command. 5 and a rotation direction switching control device for controlling the fuel injection control device 4.

Here, the fuel injection control device 4, the ignition position control device 5B and the rotation direction switching control device 8 are realized by causing a microcomputer to execute a predetermined program. Each control device may be realized using an individual microcomputer, or may be realized using the same microcomputer.

The internal combustion engine 1 is a spark ignition type reciprocating piston type internal combustion engine having a piston reciprocating in a cylinder and a crankshaft connected to the piston. The internal combustion engine to be controlled by the present invention may be a two-cycle engine or a four-cycle engine. In this example, it is assumed that the engine is a two-cycle engine.

FIG. 2 shows the relationship between the engine and the load in a case where the internal combustion engine 1 is used for driving a snowmobile. The illustrated internal combustion engine 1 has an engine body 100 having a cylinder 100a and a crankcase 100b, a piston 101 fitted in the cylinder 100a, and a crankshaft 103 connected to the piston 101 via a connecting rod 102. This is a valve type two-cycle engine. The cylinder 100a is provided with an intake port 104, an exhaust port 105, and a scavenging port (not shown).
Is connected. Although not shown, the crankcase 1
A scavenging passage is provided so as to connect the space inside 00b and a scavenging port (not shown) hidden behind the piston 101 in the state of FIG. The intake port 104 is connected to an intake manifold (not shown) via a check valve.

In FIG. 2, reference numerals 10 and 11 denote a primary pulley and a secondary pulley, respectively, which constitute a belt type continuously variable transmission (CVT), and 12 denotes a steel belt stretched over the pulleys 10 and 11. Pulleys 10 and 11
The width of each V-shaped groove can be changed to change the radial position of the slope contact with the belt.
The primary pulley 10 is attached to a crankshaft 103, and a driving wheel of a snowmobile is attached to a rotation shaft of the secondary pulley 11.

The primary pulley 10 is connected to a centrifugal clutch mechanism. The centrifugal clutch mechanism operates the belt 1 when the rotational speed of the crankshaft of the internal combustion engine is lower than a certain value.
The width of the V-shaped groove for engaging the belt 2 is increased so that the belt 12 is not driven, and the width of the V-shaped groove for engaging the belt is reduced in the region where the rotational speed of the crankshaft exceeds a certain value. Is driven, and the radial position of the inclined contact point between the belt 12 and the pulley 10 is changed according to the rotation speed. The secondary pulley 11 can also change the width of the V-shaped groove for engaging the belt 12 according to the rotation speed, and by changing the position of the slope contact with the belt 12 according to the rotation speed, Pulley 1
The speed reduction ratio between 0 and the secondary pulley 11 is changed.

In this specification, in FIG. 2, the rotation of the crankshaft 103 in the clockwise direction (the direction of arrow CL in the drawing) is defined as a forward rotation, and the rotation of the crankshaft in the counterclockwise direction is defined as a reverse rotation.

The fuel injection valve (injector) 2 shown in FIG. 1 includes, for example, a valve body having an injection port at the tip, a valve for opening and closing the injection port, and an electromagnet for driving the valve. The fuel is supplied from the fuel pump 3 at a predetermined pressure into the valve body. The fuel injection valve 2 opens the valve while a predetermined drive current is applied to the electromagnet, and injects fuel into a fuel injection space such as a space in an intake manifold of an internal combustion engine or a space (combustion chamber) in a cylinder. I do. The amount of fuel injected from the fuel injection valve 2 (fuel injection amount) is determined by the product of the pressure of the fuel supplied from the fuel pump into the valve body and the time during which the valve is open. Generally, the pressure of the fuel supplied from the fuel pump 3 to the fuel injection valve 2 is kept constant so that the injection amount can be controlled only by the time during which the valve of the fuel injection valve 2 is open.

The fuel injection control device 4 supplies a drive current to the injector 2 according to various control conditions such as the temperature of the engine, the intake air temperature, the atmospheric pressure, the opening of the throttle valve, the rotational speed of the engine, and the presence or absence of a reversal command. The fuel injection amount from the fuel injection valve 2 is controlled by controlling the timing of application and the time of application of the drive current.

The ignition device 5 includes an ignition circuit 5A for generating a high voltage for ignition when an ignition signal is given, an ignition position control device 5B for giving an ignition signal to the ignition circuit 5A at an ignition position of the internal combustion engine, And a spark plug 5C attached to a cylinder of the internal combustion engine 1.

The ignition circuit 5A includes an ignition coil and a primary current control circuit for causing a sudden change in the primary current of the ignition coil when an ignition signal is given. The change induces a high voltage for ignition in the secondary coil of the ignition coil. As the ignition circuit 5A, various types such as a capacitor discharge type circuit and a current cutoff type circuit are known, but in the present invention, the ignition position control device 5B generates the ignition position at the ignition position of the internal combustion engine. Any type of ignition circuit may be used as long as it outputs a high ignition voltage in response to the ignition signal.

The ignition position control device 5B includes a microcomputer and a signal generator for generating a signal at a predetermined rotation angle position of the internal combustion engine. The microcomputer obtains the rotation speed information and rotation angle information of the engine from the signal generated by the signal generator, and obtains the rotation speed of the engine, the engine temperature,
The ignition position of the engine is calculated according to various control conditions such as the presence or absence of a reversal command, and an ignition signal is given to the ignition circuit 5A when the calculated ignition position is detected.

The ignition plug 5C is connected to the output terminal of the ignition circuit 5A, and ignites the engine by generating a spark when the ignition circuit 5A generates a high voltage for ignition.

The rotation sensor 6 generates a pulse signal including information on the rotation speed, rotation angle, and rotation direction of the internal combustion engine. As the rotation sensor, for example, an inductor type signal generator shown in FIG. 3 is used. Can be used. In FIG. 3, reference numeral 600 denotes a rotor comprising a rotating yoke 601 attached to the crankshaft 103 of the engine and a two-stage reluctor 602 formed on the outer periphery of the rotating yoke 601. The two-stage reductor 602 has a first portion 602a located near one end in the circumferential direction and a second portion 6 located near the other end.
02b, the height of the second portion 602b is set higher than the height of the first portion 602a, and the arc length (length in the circumferential direction) of the first portion 602a is set to the second portion 60.
It is set shorter than the arc length of 2b. In the illustrated example, the rotor 600 is provided so that the first portion 602a of the reluctor is located on the front side in the rotation direction when the engine is rotating forward. As the yoke 601, a flywheel or the like attached to an engine can be used.

Numeral 603 denotes a signal generator disposed on the outer peripheral side of the rotor 601 and attached to a fixed portion such as an engine case. The signal emission 603 has a magnetic pole portion 603a1 at the tip.
Core 603a, a signal coil 603b wound around the iron core, and a permanent magnet 603c magnetically coupled to the iron core
The magnetic pole portion 603a1 is connected to the rotor 60
No. 0 is arranged in a state of facing the outer peripheral surface with a predetermined gap therebetween.

In the signal generator shown in FIG. 3, the first portion 602 of the
When a is opposed to the magnetic pole portion 603a1 of the signal emission, the magnetic flux linked to the signal coil 603b increases, and when the second portion 602b of the reluctor faces the magnetic pole portion 603a1 of the signal emission, The linked magnetic flux further increases. The signal coil 603b generates a pulse signal having a different polarity when the interlinking magnetic flux increases and when the interlinking magnetic flux decreases.

FIGS. 4A and 4B show the signal coil 6 when the engine is rotating forward and when it is rotating reversely, respectively.
The waveform of the pulse signal induced at 03b is shown with respect to the rotation angle θ of the engine. The signal coil 603b is
When the engine is rotating forward, the first part 6
02a is the angle θ at which the signal emission starts facing the magnetic pole.
1 and pulse signals S1 and S2 of one polarity (positive polarity in the illustrated example) are generated at the angle .theta.2 where the second portion 602b of the reluctor starts facing the magnetic pole portion of the signal emission, respectively. The second portion 602b of the reactor generates a pulse signal S3 of another polarity (negative polarity in the illustrated example) at the angle .theta.3 at which the opposing end of the signal emission from the magnetic pole portion is terminated.

As shown in FIG. 4B, the signal coil 603b has an angle .theta.3 at which the second portion 602b of the reluctor is opposed to the magnetic pole portion of the signal generator when the engine is rotating in the reverse direction. A positive polarity pulse signal S3 'is generated at the position,
A position at an angle .theta.2 at which the second portion 602b of the reactor stops opposing the magnetic pole portion of the signal emission;
2a generates signals S2 'and S1' of negative polarity, respectively, at the position of the angle .theta.1 where the signal emission ends facing the magnetic pole.

Strictly speaking, the position where each pulse signal is generated is a position where each pulse signal reaches a threshold level (a level recognizable by a circuit that receives the pulse signal). Is sufficiently narrow so that FIG.
, The peak position of each pulse signal is set as the generation position for convenience.

As described above, in the signal generator shown in FIG. 3, the polarity of the signal induced in the signal coil and the order of generation are different between when the engine is rotating forward and when the engine is rotating reversely. Therefore, the rotation direction of the engine can be determined by identifying the polarity of the signal obtained from the signal coil and the generation order.

That is, in the illustrated example, the signal coil 603b
Generates a pulse signal in the order of the positive pulse S1, the positive pulse S2, and the negative pulse S3, it can be determined that the engine is rotating forward, and the signal coil outputs the positive pulse S3 ', When pulse signals are generated in the order of the negative pulse S2 'and the negative pulse S1', it can be determined that the engine is rotating in the reverse direction. A means for identifying the order of generation of these pulse signals can constitute a rotation direction detecting means.

The rotation speed of the engine can be detected from the pulse generation interval, for example, the time from the generation of the pulse signal S1 to the generation of the pulse signal S3.

Further, the polar arc angle α of the reluctor 602 is appropriately set, and when the piston of the engine reaches the top dead center, the circumferential center position of the reluctor 602 is opposed to the center of the magnetic pole portion of the signal emission 603. Signal emission 60 so that
3, the pulse signals S 1 and S 3 ′ are respectively converted to α before top dead center during forward rotation and reverse rotation of the engine.
/ 2, and the generation positions of these signals S1 and S3 'are the minimum advance position of the ignition position during forward rotation and the minimum advance position of the ignition position during reverse rotation. Can be. Here, the “minimum advance position” is the ignition position closest to the top dead center among the ignition positions during steady operation of the engine, and is usually the ignition position during idling.
The polar arc angle α of the reluctor 602 is set to, for example, 10 degrees.
Assuming that the polar arc angle of the reactor is 10 degrees, the minimum advance position (ignition position at the time of idling) at the time of forward rotation and reverse rotation of the engine is a position at 5 degrees before the top dead center.

Although it is necessary to measure the angle for determining the position where each pulse signal is generated with reference to a fixed position, the position where each pulse signal is generated is usually measured with reference to the top dead center of the engine.

The pulse signal obtained from the rotation sensor 6 is
The signal is converted into a signal having a waveform recognizable by the microcomputer by a waveform shaping circuit (not shown), and is supplied to a predetermined input port of the microcomputer.

The microcomputer obtains rotation angle information, rotation speed information, and rotation direction information of the engine from the signal given from the rotation sensor, and obtains the intake air temperature of the engine, the engine temperature from various sensors (not shown). Calculation processing for obtaining information such as the temperature of the cooling water (temperature of the cooling water), the opening degree of the throttle valve, the atmospheric pressure, etc., and realizing the fuel injection control device 4, the ignition position control device 5B and the rotation direction switching control device 8, respectively. I do.

In the example shown in FIG. 1, the inversion command generating section 7 includes a resistor 7A having one end connected to the positive output terminal of a constant voltage DC power supply circuit (not shown), and a resistor 7A connected between the other end of the resistor 7A and ground. And an inversion command switch 7B connected thereto. An output terminal on the negative side of a constant-voltage DC power supply circuit (not shown) is grounded, and an output voltage of the power supply circuit is applied to both ends of a series circuit including a resistor 7A and a switch 7B. Resistance 7
An output terminal is derived from a connection point between A and the switch 7B,
A signal obtained between the output terminal and the ground is input to a microcomputer (not shown), and the rotation direction switching control device 8
Is used as a signal for giving an inversion command to. Switch 7
B is kept off, for example, when the engine is rotating forward, and is turned on when the engine is rotating reversely. The switch 7B is kept on during the reverse rotation of the engine,
It is turned off when the engine is rotated forward.

The signal generated by the inversion command generator 7 takes a high level when the switch 7B is off, and a zero level when the switch 7B is on. The rotation direction switching control device 8 determines that an inversion command for instructing to invert the rotation direction of the engine is given each time the level of the signal given from the inversion command generating unit changes.

When reversing the rotation direction of the engine, first, a throttle operating member such as a throttle lever is operated so that the opening of the throttle valve becomes a value near the minimum value (a value near the opening during idling). , The switch 7B of the inversion command generator 7 is operated.

The rotation direction switching control device 8 includes a switch 7B
Is operated and a reversal command is given from the reversal command generator 7 to switch various control (control of the ignition device and the fuel injection device) performed by the microcomputer to a control mode at the time of reversal, as follows. To perform a process for reversing the engine.

In a preferred embodiment, when a reversal command is issued, a fuel injection quantity reduction command is first given to the fuel injection control device 4 to reduce or increase the fuel injection quantity from a specified quantity, thereby controlling the internal combustion engine. The air-fuel ratio of the air-fuel mixture is changed to a lean (lean) side or a rich (rich) side within a range not to stop.

FIG. 9 shows the relationship between the air-fuel ratio of the air-fuel mixture and the engine speed. As shown in FIG. 9, when the air-fuel ratio is changed to the lean side or the rich side, the engine speed is reduced. It is going down. In FIG. 9, A1 is a lean limit value of the air-fuel ratio that can maintain the rotation of the engine.
If the air-fuel ratio is changed further to the lean side from the limit value A1, the engine stops. A2 is the air-fuel ratio when the engine generates the maximum torque, and A3 is the rich limit value of the air-fuel ratio that can maintain the rotation of the engine. If the air-fuel ratio is changed to a richer side than A3, the engine stops.

After the air-fuel ratio is changed to the lean side or the rich side by decreasing or increasing the fuel injection amount, the ignition position of the internal combustion engine is advanced while the opening of the throttle valve is kept at the minimum value. The ignition direction is gradually advanced, and the rotation direction of the internal combustion engine is reversed by an over-advanced ignition position.

When it is detected that the rotation direction of the internal combustion engine has been reversed, the ignition position of the internal combustion engine is changed to a rotation angle position suitable for maintaining the rotation of the internal combustion engine in the reversed direction, and the air-fuel mixture is changed. The engine is ignited in a state where the air-fuel ratio has been returned to the normal value.

FIG. 5 shows the relationship between the ignition position and the rotation angle of the engine. In FIG. 5, CL indicates the forward rotation direction of the engine, and TDC indicates the top dead center of the engine (the piston is at the top dead center). At the time of rotation of the crankshaft). When the engine is rotating in the direction of the arrow CL shown in the figure, the range between the position θa where the ignition position is slightly advanced from the top dead center TDC and the position θb where the ignition position is further advanced is defined as an advance angle range during steady operation. Within this advance range, the ignition position is changed according to the change in the rotation speed. The range further advanced than the ignition position θb is the over-advanced range, and the position θd is the final over-advanced position of the ignition position when reversing the rotation direction of the engine by the method of the present invention. That is, when reversing the rotational direction of the engine, the ignition position is advanced beyond the steady-state advance angle range θa to θb to the final over-advance angle position θd.

In FIG. 5, θa ′ to θb ′ are advancing ranges in a steady state when the engine is rotating in a direction opposite to the direction of arrow CL shown in the drawing, and θd ′ is a rotation angle range in the opposite direction. This is the final over-advanced position when reversing the rotation direction of the engine. The final over-advance angle positions θd and θd 'are not necessarily constant, and may change depending on the state of the engine.

In FIG. 5, BTDC is the top dead center TD
A means that the rotation angle range is on the more advanced side than C.
TDC means a rotation angle range on the retard side from the top dead center.

In a preferred embodiment of the present invention, a change in the ignition position and a change in the engine speed when reversing the rotation direction of the internal combustion engine that is rotating forward are described with reference to FIGS. 6 (A) and 6 (B). This will be described in detail. FIG. 6A shows the time t.
6B shows the change in the rotation speed N of the engine with respect to time t.

In order to reverse the rotation of the internal combustion engine, FIG.
At time t0 shown in (A) and (B), when the opening of the throttle valve is reduced to the minimum value, the ignition position θi of the engine becomes the position θa closest to the top dead center. When an inversion command is given at time t1, the ignition position gradually changes to the advanced side, and advances beyond the steady state maximum advanced position .theta.b to the over advanced side.

FIG. 8 shows the relationship between the rotation angle θ of the engine and the pressure P in the cylinder. In FIG. 8, curve a shows the case where ignition is performed at an appropriate position, and curve b shows the advance angle. This shows a case where ignition is performed at the set position. As shown in the figure, as the ignition position is advanced, the pressure in the cylinder when the ignition operation is performed becomes lower, and the position where the pressure in the cylinder becomes maximum after ignition is on the advanced side (above the engine). Dead center T
(Away from DC). Therefore, as the ignition position is advanced, the force for pushing the piston back increases, and the rotational speed of the engine gradually decreases.

At time t2 shown in FIG. 6, when the ignition position .theta.i is advanced to a certain position .theta.d, the force for pushing back the piston overcomes the force of the piston for rising toward the top dead center TDC. And the rotation direction of the engine is reversed. In the present invention, a rotation direction detecting means for detecting the reversal of the rotation direction of the engine is provided. The reversal of the rotation direction of the engine can be detected, for example, by identifying the order in which a rotation sensor as shown in FIG. 3 generates a positive pulse signal and a negative pulse signal on software.

At time t3 immediately after time t2 when the rotation direction of the engine is reversed, when it is detected that the rotation direction of the engine has been reversed, the ignition position is set to a rotation angle position suitable for maintaining the rotation of the internal combustion engine. By shifting, the rotation of the internal combustion engine in the reverse direction is maintained. In the example shown in FIG.
At time t3, the ignition position of the engine is shifted to the top dead center TDC.

According to the above-described method, since the rotation direction of the internal combustion engine can be reversed without causing any misfire, it is possible to prevent the discharge of unburned gas when switching the rotation direction of the engine. Thus, it is possible to eliminate the possibility that afterfire is generated at the time of switching the rotation direction or the atmosphere is polluted.

As described above, if the ignition position is gradually advanced to the over-advanced side, the ignition operation is performed when the rotational speed of the engine decreases and approaches the state immediately before stopping. Each time there is an opportunity to reverse the rotation direction of the engine, it is possible to surely switch the rotation direction of the engine.

A flow chart showing an outline of an algorithm of an interrupt routine executed when an inversion command is generated among the programs executed by the microcomputer in order to realize the rotation direction switching control device 8 which performs the above-described series of processes. As shown in FIG.

In the case of the algorithm shown in FIG. 10, when an inversion command is generated, first, in step 1, the fuel injection amount is reduced below a prescribed amount, and the air-fuel ratio is reduced within a range where the engine is not stopped. Change to the side. Next, at step 2, it is determined whether or not the throttle opening detected by a throttle opening sensor (not shown) is minimum (whether or not the driver has fully throttled the throttle). As a result, when the throttle opening is not the minimum, the process for reversing the rotation direction of the engine is stopped, and the calculation of the engine rotation speed, the calculation of the ignition position during steady operation, the calculation of the fuel injection time, and the like are performed. And returns to the main routine (not shown).

If it is determined in step 2 that the opening of the throttle valve is at a minimum, the process proceeds to step 3 in which a process for advancing the next ignition position by Δθi from the previous ignition position is performed. Let it do.

The ignition position at the time of steady operation is defined by the number of clock pulses (ignition position) to be measured while the engine rotates from the reference position to the ignition position with a specific position of the rotational angle position of the engine as a reference position. (Measurement count value). The microcomputer starts counting of the ignition position measurement count value calculated when the reference position is detected, and when the counting is completed, gives the ignition signal to the ignition circuit 5A to perform the ignition operation. As the reference position for starting the measurement of the ignition position, for example, the position of θ3 (when the engine is rotating forward) and the position of θ1 (when the engine is rotating backward) shown in FIG. 4 can be used.

In step 3 of FIG.
In order to advance the angle by θi, a process of subtracting a count value corresponding to Δθi from the already calculated ignition position measurement count value may be performed.

After the ignition position has been advanced by Δθi, it is determined in step 4 whether or not the rotation direction of the engine has been reversed. If the rotation direction has not been reversed, the process returns to step 2 and Repeat the same operation.

If it is detected in step 4 that the rotation direction of the engine has been reversed, the routine proceeds to step 5 where the fuel injection amount is returned to the specified amount, the air-fuel ratio of the air-fuel mixture is returned to a normal value, and the ignition position is set. Then, the engine is shifted to a set ignition position (top dead center in the example shown in FIG. 6) suitable for maintaining the rotation of the engine.

Since the top dead center of the engine is an effective ignition position for maintaining the rotation of the engine in either the forward or reverse direction, it is determined as the ignition position immediately after the rotation of the engine is reversed. Is safe to choose the top dead center. However, the present invention is not limited to the case where the ignition position immediately after the rotation of the engine is reversed is taken as the top dead center. May be shifted to a position slightly advanced from the top dead center (for example, the position of θ3 in FIG. 6B).

As described above, when the reversal command is given, if the ignition position is gradually advanced to the over-advanced side until the rotation direction of the internal combustion engine is reversed, It is inevitable that the period in which the engine is ignited in the corner state becomes longer. When the ignition position is over-advanced, so-called knocking occurs and a large force is applied to the piston.
It is preferable that the period in which the over-advance angle occurs is as short as possible.

In order to shorten the engine in which an over-advance state occurs, the ignition position of the internal combustion engine is kept in a state where the opening of the throttle valve is kept close to the opening during idling when the reversal command is given. A first over-advancing process in which the rotation speed of the internal combustion engine is reduced by gradually advancing the rotation to the over-advanced side, and when the rotation speed of the internal combustion engine is reduced to a set step over-advance start rotation speed. A second over-advancing process for advancing the ignition position to a set final over-advance position in a step-like manner, and the rotation direction of the internal combustion engine is changed by the rotation direction detecting means in the second over-advance process. When the reversal is detected, the ignition position may be shifted to a rotation angle position suitable for maintaining the rotation of the internal combustion engine in the reversed direction.

FIGS. 7A and 7B show a change in the ignition position and a change in the engine speed when the first over-advancing process and the second over-advancing process are performed as described above. It is shown. That is, when an inversion command is given at time t1,
A first over-advancing process for gradually advancing the ignition position θi from the ignition position θa at idling is performed, and at time t2, the rotation speed N is set to a preset step over-advance start rotation speed Ns
When the ignition position is lowered to a position where the rotational direction of the engine is reversed (final over-advance angle), the ignition position is advanced stepwise from the ignition position θs at time t2 by βx (x = 1, 2,. Position) is performed. As a result, the rotation direction of the engine is reversed at time t3. At time t4, when it is detected that the rotation direction of the engine has been reversed, the ignition position is shifted to an ignition position (top dead center in the illustrated example) suitable for maintaining the rotation direction of the engine in the reversed direction.

Here, the magnitude of the step advance angle amount βx is
It is appropriately selected according to the temperature of the air-fuel mixture. In an internal combustion engine, the higher the temperature of the air-fuel mixture, the faster the propagation speed of the flame generated when the fuel is ignited, and the shorter the time required for the explosive force applied to the piston after ignition to reach the maximum value. Accordingly, when the temperature of the air-fuel mixture at the time of reversing the engine is high, the advance amount β when the ignition position is over-advanced in a step-like manner
x can be reduced to β1 shown in FIG. When the temperature of the air-fuel mixture is low, the advance amount when the ignition position is over-advanced in a step-like manner is represented by β in FIG.
Need to be as much as 3.

As described above, in order to change the magnitude of the step advancing angle βx according to the temperature of the air-fuel mixture, an engine temperature sensor for detecting the temperature of the internal combustion engine and an intake air temperature for detecting the intake temperature of the internal combustion engine At least one of the sensors is provided, and when the temperature detected by the temperature sensor is lower, the temperature detected by the temperature sensor is set so as to increase the amount of advance when the ignition position is over-advanced in a step-like manner. The final over-advanced position may be changed accordingly.

When the internal combustion engine is determined, the relationship between the ignition position and the rotational speed of the engine is substantially determined, so that the ignition position θs corresponding to the step over-advance start rotational speed Ns can be obtained in advance. Therefore, the ignition position θs is set as a step over-advance angle start position, and when the ignition position of the internal combustion engine is advanced to the set step over-advance angle start position θs, the ignition position is set at the final over-advance position. The rotational direction of the engine may be reversed by advancing the angular position to a stepped shape.

Since the rotation speed when the rotation of the engine is reversed is very low and unstable, it is detected that the rotation direction of the engine has been reversed with the ignition position advanced to the final over-advanced position. It is not always easy. Therefore, it is preferable to confirm that the rotation direction of the engine has been reversed after shifting the ignition position from the final over-advanced position to the post-reversal ignition position.

For this purpose, when an inversion command is given, the ignition position of the internal combustion engine is gradually advanced to the over-advanced side while the opening of the throttle valve is kept near the opening during idling. A first over-advance process in which the rotation speed of the internal combustion engine is reduced by the operation, and when the rotation speed of the internal combustion engine drops to a set step over-advance start rotation speed, or when the ignition position is a step over-advance start position. A second over-advance process in which the ignition position is advanced stepwise to the set final over-advance position when the ignition position is advanced to at least one cylinder at the final over-advance position; After the over-advancing process is completed, the ignition position of each cylinder is shifted to the set ignition position set near the top dead center to determine whether or not the rotation direction of the engine is reversed. What is necessary is just to make it perform.

In order to prevent the engine from stopping when reversing the direction of rotation of the engine, the ignition in the second over-advancing angle process is performed once in at least one cylinder or once in each cylinder. It is preferable to avoid performing ignition at the final over-advanced position more than once in each cylinder as much as possible.

In order to inform the driver that the engine has been reversed, when the rotation direction of the engine is detected to be reversed in the above-described rotation direction discrimination process, a display means for displaying that the rotation direction of the engine has been reversed is displayed. It is desirable to perform the operation.

Further, in order to surely perform the reversal of the engine, when it is detected that the rotation direction of the engine has not been reversed in the above-described rotation direction discrimination process, until the rotation direction of the engine is confirmed to be reversed. A series of processes from the first over-advance angle process to the rotation direction discrimination process is repeated, and after it is detected in the rotation direction discrimination process that the rotation direction of the engine is reversed, the rotation direction is reversed. Preferably, the engine is operated.

FIG. 11 shows a program executed by the microcomputer when the first over-advancement process and the second over-advancement process are performed as shown in FIGS. 7A and 7B. Among them, an algorithm of an interrupt routine executed when an inversion command is given is shown.

In the case of following the algorithm of FIG. 11, when an inversion command is given, first, in step 1, the fuel injection amount is reduced, and the air-fuel ratio is changed to the lean side within a range where the engine is not stopped. Next, at step 2, it is determined whether or not the throttle opening is kept at the minimum value. If the throttle opening is not at the minimum, the process of reversing the rotation direction of the engine is stopped and the process returns to the main routine. If it is confirmed in step 2 that the throttle opening is kept at the minimum value, it is determined in step 3 whether or not the engine speed N has decreased to the step over-advance start rotation speed Ns. As a result, when it is determined that the rotation speed N has not decreased to the step over-advance start rotation speed Ns, the process proceeds to step 4 to advance the ignition position by Δθi, and returns to step 2.

If it is determined in step 3 that the rotation speed N has decreased to the step over-advance start rotation speed Ns, then in step 5 the step speed corresponding to the detection value of the sensor detecting the intake air temperature is determined. The advance amount βx is determined, and in step 6, the ignition position is advanced stepwise by the step over-advance amount βx. Then step 7
, It is determined whether or not one ignition has been performed in all cylinders of the engine. When it is confirmed that one ignition has been performed in each cylinder, the process proceeds to step 8. In step 8, the fuel injection amount is returned to a specified amount (an amount necessary for bringing the air-fuel ratio to a normal value), and in step 9, the ignition position is shifted to near the top dead center. If the ignition position is near the top dead center, the engine can rotate regardless of whether the rotation direction of the engine is reversed or not, so that it is possible to prevent the engine from stopping.

After shifting the ignition position to the top dead center, the rotational direction of the engine is determined in step 10. As a result, when the rotation direction is reversed, the process returns to the main routine.
If it is determined in step 10 that the rotation direction has not been reversed, the process returns to step 1 and the same process as described above is repeated.

In the examples shown in FIGS. 10 and 11, when an inversion command is given, the fuel injection amount is first reduced in step 1 to change the air-fuel ratio to the lean side. The fuel injection amount may be increased, and the air-fuel ratio may be changed to the rich side within a range where the engine is not stopped.

In order to facilitate the reversal of the rotational direction of the engine, the air-fuel ratio of the air-fuel mixture is first changed to the lean side or the rich side when the reversal command is given as described above. Although preferred, the process of changing the air-fuel ratio may be omitted.

In the example shown in FIG. 10, the magnitude of the step advance angle is changed in accordance with the intake air temperature.
The temperature of the engine (the temperature of the cooling water of the engine) may be detected and the magnitude of the step advance amount may be changed according to the temperature of the engine. Alternatively, the magnitude of the step over-advance angle may be determined.

Also, regardless of the intake air temperature and the engine temperature, the amount of step over-advance of the ignition position is constant (a value that can reverse the rotation direction of the engine even when the temperature of the air-fuel mixture is low).
It may be.

In the above example, a fuel injection valve (injector) is used as a means for supplying fuel to the internal combustion engine. However, the present invention can be applied to a case where a carburetor is used as means for supplying fuel to the internal combustion engine. Of course.

In order to change the air-fuel ratio of the air-fuel mixture when using a carburetor, for example, a valve is inserted between the float chamber of the carburetor and the nozzle, and the injection from the carburetor nozzle is performed according to the opening degree of the valve. What is necessary is just to change the amount of fuel to be used.

In the above example, when the rotation direction of the engine is reversed, the driver keeps the opening of the throttle valve at the minimum value. However, the throttle valve is operated by an electric actuator. When the reversal command is given, the actuator may be controlled so that the opening of the throttle valve is maintained at the minimum value until the reversal of the rotation direction of the engine is completed.

When the direction of rotation of the engine is reversed and the vehicle or the like is backed, it is dangerous if the rotation speed of the engine rises without limit. Therefore, when rotating the engine in the direction in which the vehicle or the like is caused to reverse, it is preferable to limit the rotation speed of the engine to a predetermined limit value or less. In order to limit the rotation speed of the engine, for example, the ignition position may be retarded when the rotation speed of the engine exceeds the limit value.

[0103]

As described above, according to the present invention, by gradually advancing the ignition position of the internal combustion engine to the over-advanced side, the rotation direction of the engine is reversed, and after the reversal, the ignition position is changed. Since the rotation of the engine is maintained by shifting to a rotation angle position suitable for maintaining the rotation of the internal combustion engine, the rotation direction can be reversed without causing any misfire of the internal combustion engine. Therefore, it is possible to prevent the unburned gas from being exhausted when switching the rotation direction of the engine, and to eliminate the possibility of generating afterfire or polluting the atmosphere when switching the rotation direction.

In the present invention, when the rotational speed of the engine is reduced to the step over-advance start rotation speed due to the over-advance of the ignition position, or when the ignition position is advanced to the step over-advance start position, the ignition position Over-advancing to the final ignition position in a step-like manner, compared to a case where the ignition position is gradually advanced to the final over-advance position where the rotation direction of the engine is reversed, in a shorter time. Since the ignition position can be advanced to the final over-advanced position, the rotation direction of the engine can be reversed in a short time.

In the present invention, when the ignition position is over-advanced in a step-like manner, the period in which knocking occurs due to the over-advancement of the ignition position can be shortened, so that the rotation direction of the engine is reversed. In this case, it is possible to prevent unnecessary impact on the engine.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration example of a control device used to carry out a method according to the present invention.

FIG. 2 is an explanatory diagram showing an example of an internal combustion engine to which the method of the present invention is applied and an example of a transmission provided between the engine and driving wheels of a vehicle or the like.

FIG. 3 is a configuration diagram showing an example of a rotation sensor used to detect the rotation of the engine when performing the method of the present invention.

FIG. 4 is a waveform diagram showing a waveform of a signal obtained from the rotation sensor of FIG. 3;

FIG. 5 is an explanatory diagram for explaining a change in an ignition position during forward rotation and reverse rotation of the engine.

FIG. 6 is a diagram showing a temporal change of an ignition position and a temporal change of an engine rotation speed in one embodiment of the present invention.

FIG. 7 is a diagram showing a temporal change of an ignition position and a temporal change of an engine speed in another embodiment of the present invention.

FIG. 8 is a diagram showing a relationship between a pressure in a cylinder and a rotation angle of the internal combustion engine.

FIG. 9 is a diagram showing a relationship between an air-fuel ratio of an air-fuel mixture supplied to an engine and a rotation speed of the engine.

FIG. 10 is a flowchart showing an algorithm of an interrupt routine of a program executed by the microcomputer when an inversion command is given in one embodiment of the present invention.

FIG. 11 is a flowchart illustrating an algorithm of an interrupt routine of a program executed by a microcomputer when an inversion command is given in another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 internal combustion engine 2 fuel injection valve 3 fuel pump 4 fuel injection control device 5 ignition device for internal combustion engine 6 rotation sensor 7 inversion command generation unit 8 rotation direction switching control device

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI F02D 43/00 301 F02P 5/15 B (72) Inventor Hiroyasu Nito 3744 Ooka, Numazu-shi, Shizuoka Prefecture Kokusan Denki Co., Ltd. (56 References JP-A-3-64668 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02P 5/15 F02D 27/00 F02D 41/16 F02D 43/00 301

Claims (10)

(57) [Claims] 1. A rotation of a spark ignition type reciprocating piston type internal combustion engine having a piston reciprocating in a cylinder and a crankshaft connected to the piston and being ignited by an ignition device capable of controlling an ignition position. In the method for switching the direction, when a reversal command for reversing the rotation direction of the internal combustion engine is given, the opening of the throttle valve is kept close to the opening during idling, and The ignition position is gradually advanced to the over-advanced side, and the rotation direction of the internal combustion engine is reversed by the over-advanced ignition position. When it is detected that the rotation direction of the internal combustion engine is reversed, the ignition is performed. A method for switching a rotation direction of an internal combustion engine, comprising shifting a position to a rotation angle position suitable for maintaining rotation of the internal combustion engine in a reversed direction. 2. A rotation of a spark-ignition type reciprocating piston type internal combustion engine having a piston reciprocating in a cylinder and a crankshaft connected to the piston, and ignited by an ignition device capable of controlling an ignition position. In the method for switching the direction, when a reversal command for reversing the rotation direction of the internal combustion engine is given, the opening of the throttle valve is kept close to the opening during idling, and A first over-advance process in which the rotation speed of the internal combustion engine is reduced by gradually advancing the ignition position to the over-advance side, and a step over-advance start rotation speed at which the rotation speed of the internal combustion engine is set. And performing a second over-advance process in which the ignition position is advanced in a step-like manner to the set final over-advance position when the internal combustion engine is lowered. When it is detected that the direction has been reversed, the ignition position is shifted to a rotational angle position suitable for maintaining the rotation of the internal combustion engine in the reversed direction. Method. 3. The rotation of a spark-ignition reciprocating piston type internal combustion engine having a piston reciprocating in a cylinder and a crankshaft connected to the piston, and ignited by an ignition device capable of controlling an ignition position. In the method for switching the direction, when a reversal command for reversing the rotation direction of the internal combustion engine is given, the opening of the throttle valve is kept close to the opening during idling, and A first over-advance process in which the rotation speed of the internal combustion engine is reduced by gradually advancing the ignition position to the over-advance side, and the ignition position of the internal combustion engine is advanced to a set step over-advance start position A second over-advancing process of stepwise advancing the ignition position to a set final over-advance position when the vehicle is turned, and in the second over-advancing process, the rotation direction of the internal combustion engine When it was inverted is detected, the ignition position, the rotation direction switching control method for an internal combustion engine, characterized in that shifting to the rotational angular position suitable for maintaining the rotation of the internal combustion engine to the inverted direction. 4. A rotation of a spark-ignition reciprocating piston type internal combustion engine having a piston reciprocating in a cylinder and a crankshaft connected to the piston, and ignited by an ignition device capable of controlling an ignition position. In the method for switching the direction, when a reversal command for reversing the rotation direction of the internal combustion engine is given, the opening of the throttle valve is kept close to the opening during idling, and A first over-advance process in which the rotation speed of the internal combustion engine is reduced by gradually advancing the ignition position to the over-advance side, and a step over-advance start rotation speed at which the rotation speed of the internal combustion engine is set. When lowered, the ignition position is advanced in a stepwise manner to a set final over-advanced position, and at least one cylinder of the internal combustion engine is ignited at the final over-advanced position. After the over-advancing process 2 and the second over-advancing process are completed, the ignition position of each cylinder is shifted to the set ignition position set near the top dead center to determine whether the rotation direction of the engine is reversed. And performing a rotation direction determining step of determining whether or not the rotation direction has been changed. 5. A rotation of a spark ignition type reciprocating piston type internal combustion engine having a piston reciprocating in a cylinder and a crankshaft connected to the piston and being ignited by an ignition device capable of controlling an ignition position. In the method for switching the direction, when a reversal command for reversing the rotation direction of the internal combustion engine is given, the opening of the throttle valve is kept close to the opening during idling, and A first over-advance process in which the rotation speed of the internal combustion engine is reduced by gradually advancing the ignition position to the over-advance side, and the ignition position of the internal combustion engine is set in the first over-advance process When the ignition position is advanced to a step over-advance start position, the ignition position is advanced stepwise to a set final over-advance position, and at least one engine of the internal combustion engine is at the final over-advance position. After the second over-advancing process is completed, and after the second over-advancing process is completed, the ignition position of each cylinder is shifted to the set ignition position set near the top dead center to change the rotation direction of the engine. A rotation direction determining step of determining whether or not the rotation has been reversed. 6. A rotation of a spark ignition type reciprocating piston type internal combustion engine having a piston reciprocating in a cylinder and a crankshaft connected to the piston and being ignited by an ignition device capable of controlling an ignition position. In the method for switching the direction, when a reversal command for reversing the rotation direction of the internal combustion engine is given, the opening of the throttle valve is kept close to the opening during idling, and A first over-advance process in which the rotation speed of the internal combustion engine is reduced by gradually advancing the ignition position to the over-advance side, and a step over-advance start rotation speed at which the rotation speed of the internal combustion engine is set. When the ignition position is lowered, the ignition position is advanced stepwise to a set final over-advance position, and at least one cylinder of the internal combustion engine is ignited at the final over-advance position. After the over-advance process and the second over-advance process are completed, the ignition position of each cylinder is shifted to the set ignition position set near the top dead center to determine whether the rotation direction of the engine is reversed. Performing a rotation direction determination step of determining whether the rotation direction of the engine has not been reversed in the rotation direction determination step, until it is confirmed that the rotation direction of the engine has been reversed. A series of processes from the first over-advance angle process to the rotation direction discriminating process is repeated, and after it is detected in the rotation direction discriminating process that the rotation direction of the engine is reversed, the rotation direction is reversed. A method for controlling the switching of the rotation direction of an internal combustion engine, characterized by causing the engine to operate. 7. A rotation of a spark ignition type reciprocating piston type internal combustion engine having a piston reciprocating in a cylinder and a crankshaft connected to the piston, and ignited by an ignition device capable of controlling an ignition position. In the method for switching the direction, when a reversal command for reversing the rotation direction of the internal combustion engine is given, the opening of the throttle valve is kept close to the opening during idling, and A first over-advance process in which the rotation speed of the internal combustion engine is reduced by gradually advancing the ignition position to the over-advance side, and when the ignition position of the internal combustion engine is advanced to a step over-advance start position. A second over-advanced ignition step for igniting at least one cylinder of the internal combustion engine at the final over-advanced position by step-advancing the ignition position to a set final over-advanced position; After the second over-advancing process is completed, the ignition position of each cylinder is shifted to the set ignition position set near the top dead center to determine whether the rotation direction of the engine is reversed. Performing a direction discriminating step. If it is detected in the rotational direction discriminating step that the rotational direction of the engine is not reversed, the first excessive travel is performed until it is confirmed that the rotational direction of the engine has been reversed. A series of processes from the angular process to the rotation direction determination process is repeated, and after the rotation direction of the engine is detected to be reversed in the rotation direction determination process, the operation of the engine with the rotation direction reversed is performed. A method for controlling the rotation direction switching of an internal combustion engine, wherein the method is performed. 8. When the rotation direction of the engine is detected to be reversed in the rotation direction determination step, a display operation for displaying that the rotation direction of the engine has been reversed is performed. Item 7. A method for controlling the rotation direction of an internal combustion engine according to Item 4, 5, 6, or 7. 9. An engine temperature sensor for detecting a temperature of the internal combustion engine and at least one of an intake air temperature sensor for detecting an intake air temperature of the internal combustion engine, wherein the temperature detected by the temperature sensor is low. 9. The position of the final over-advanced angle according to the temperature detected by the temperature sensor so that the amount of advance at the time of the step-like advance is increased as the case may be.
The control method for switching the rotation direction of the internal combustion engine according to any one of the above. 10. When the ignition position of the internal combustion engine is gradually advanced after the inversion command signal is given, the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine is maintained within a range not to stop the internal combustion engine. The method according to any one of claims 1 to 9, wherein the output torque of the internal combustion engine is decreased by changing the output torque to the rich side or the rich side.