TWI476320B - Reduce the engine starting torque control method - Google Patents

Description

Control method for reducing engine starting torque

The present invention relates to a control method for an engine, and more particularly to a control method for reducing the starting torque of an engine.

Please refer to FIG. 9 , which is a schematic diagram of a known four-stroke engine 50 . The engine 50 includes a cylinder 51 , an intake valve 52 , an exhaust valve 53 , a piston 54 , an igniter 55 , and a connecting rod 56 . With a crankshaft 57.

The cylinder 51 includes an intake pipe 511, an exhaust pipe 512 and a chamber 513. The chamber 513 is connected to the intake pipe 511 and the exhaust pipe 512. The intake pipe 511 is provided with a manifold pressure. A sensor for sensing the air pressure of the intake pipe 511.

The intake valve 52 and the exhaust valve 53 are respectively disposed at the ends of the intake pipe 511 and the exhaust pipe 512 of the cylinder 51, and one end of the intake valve 52 and the exhaust valve 53 respectively have a plug portion 520, 530. The other end of the gas valve 52 is connected to a cam shaft, and the other end of the exhaust valve 53 is connected to another cam shaft. When the two cam shafts rotate, the intake valve 52 and the exhaust valve 53 can be respectively driven to close or open. The intake pipe 511 and the exhaust pipe 512.

The piston 54 is housed in a chamber 513 of the cylinder 51.

The igniter 55 is disposed in the cylinder 51.

One end of the connecting rod 56 is pivotally connected to the bottom of the piston 54 , and the other end is pivotally connected to the crankshaft 57 at a position offset from the axis 570 . Since the connecting rod 56 is pivotally connected to the axis 570 of the crankshaft 57 , Therefore, when the crankshaft 57 rotates, the crankshaft 57 drives the piston 54 to reciprocate in the chamber 513 through the connecting rod 56. The end of the crankshaft 57 is coupled to a starter motor that is responsible for driving the crankshaft 57 to rotate when the engine 50 is started.

A crank position sensor is disposed outside the end of the crankshaft 57, which is generally a Hall element. When the crankshaft 57 rotates, the crank position sensor can generate a square wave signal. An electronic control unit (ECU) of the vehicle is electrically connected to the crank position sensor and the manifold pressure sensor, and the electronic control unit calculates the engine speed (rpm) and the crank angle according to the square wave signal, and receives the manifold pressure. The pressure value produced by the sensor.

Referring to FIG. 10, the four-stroke engine performs four strokes to complete one engine cycle, which is an intake stroke, a compression stroke, a power stroke and an exhaust stroke, wherein each rotation of the crankshaft 57 represents 360 degrees. The two strokes are executed, so the crankshaft 57 needs to be rotated 720 degrees to complete the four strokes. Generally, the crank angle is defined according to the position of the piston 54. For example, the piston 54 can reach the innermost end position of the chamber 513 as the corresponding crank angle. At 0 degrees and 360 degrees, the outermost end position of the piston 54 up to the chamber 513 corresponds to a crank angle of 180 degrees and 540 degrees.

Please refer to FIG. 11, and the four strokes will be separately described below.

1. Intake stroke: the crankshaft 57 rotates to drive the piston 54 to move outward from the innermost end of the chamber 513, while the exhaust valve 53 closes the exhaust pipe 512, and the intake valve 52 opens the intake pipe 511 when When the piston 54 moves outward, the pressure in the chamber 513 is lowered, so that the fuel gas can be drawn into the chamber 513 through the intake pipe 511, and the position of the piston 54 in the intake stroke can be sequentially changed to the crankshaft. The angle is 0~180 degrees.

2. Compression stroke: the crankshaft 57 rotates to drive the piston 54 to move into the chamber 513, and the exhaust valve 53 and the intake valve 52 respectively close the exhaust pipe 512 and the intake pipe 511 due to the inside of the intake pipe 511. The air cannot reach the chamber 513, causing the air pressure in the intake pipe 511 to increase, so that the pressure value sensed by the manifold pressure sensor will increase, and the position change of the piston 54 in the compression stroke can be sequentially corresponding. The crank angle is 180 to 360 degrees; as the piston 54 moves inward, since the fuel gas has no space to be discharged, the pressure of the fuel gas will increase.

3. Power stroke: The igniter 55 ignites the compressed fuel gas to cause the fuel gas to explode. The pressure after the explosion will push the piston 54 outward, thereby serving as the power source of the traveling vehicle, and the position of the piston 54 in the power stroke. The change can be sequentially corresponding to the crank angle of 360 to 540 degrees.

4. Exhaust stroke: the crankshaft 57 rotates to drive the piston 54 to move into the chamber 513, while the exhaust valve 53 opens the exhaust pipe 512, and the intake valve 52 closes the intake pipe 511 when the piston 54 When moving inward, the exhaust gas generated after the explosion can be exhausted to the chamber 513 through the exhaust pipe 512, wherein the position change of the piston 54 in the exhaust stroke can be sequentially corresponding to the crank angle of 540 to 720 degrees (ie, return to 0 degrees) to complete a four-stroke engine cycle.

The electronic control unit can determine the stroke that the engine 50 is performing according to the pressure value of the manifold pressure sensor. For example, as shown in FIG. 11, the electronic control unit can compare the pressure values of the crankshaft 57 at 180 degrees and 540 degrees, respectively. If it is judged that the pressure of the crankshaft 57 at 180 degrees is less than the pressure at 540 degrees, it means that the crankshaft 57 has just completed the intake stroke at 180 degrees, and the next 180 to 360 degrees will perform the compression stroke, 360~540. The degree corresponds to the power stroke, and the 540 to 720 degrees corresponds to the exhaust stroke, thereby defining the crank angle corresponding to each of the four strokes.

When the vehicle is turned off, the igniter 55 stops operating, and the intake pipe 511 no longer introduces fuel gas, and the crankshaft 57 is operated only by the inertia force. At this time, if the engine 50 enters the compression stroke, the chamber 513 is formed into a chamber. In a confined space, the gas pressure in the chamber 513 will cause resistance to the propelling piston 54. The crankshaft 57 cannot have sufficient power to propel the piston 54 into the chamber 513; therefore, after the vehicle is turned off, the engine 50 usually stops at The state of the compression stroke.

When the vehicle is restarted, the engine 50 must provide more force to complete the compression stroke to overcome the gas resistance in the chamber 513 to urge the stationary piston 54 to compress the gas in the chamber 513. Until the compression stroke is completed. For the starter motor, each time the vehicle is started, it must load a large current and a large torque to provide sufficient force to overcome the gas pressure. For a long time, the performance of the motor will be affected.

In order to avoid stopping the compression stroke after the engine is turned off, there are related improvement technologies, such as the idle speed flameout system published by Takeshi Yanagisawa et al. in 2010, which is to control a motor to drive the engine when the engine is turned off and completely stopped. The previous stroke is rotated until the engine stops at the non-compressed stroke; however, the method is still to control the motor to drive the crankshaft rotation after the engine is completely stopped, the motor must be able to load a large current, and the cost required to perform the method is high.

In addition, another method is to provide an electromagnet outside the crankshaft. If the engine speed drops to a threshold, the electromagnet will be activated to generate suction to the crankshaft to stop the crankshaft in an uncompressed stroke, however, when the electromagnet is activated The electromagnet will adsorb metal powder and contaminate the engine, causing engine damage.

In view of the fact that the engine is stopped after the engine is turned off, the starting motor is required to load the engine in order to start the engine, and it is necessary to load a large current and a large torque. Therefore, the main object of the present invention is to provide a control method for reducing the starting torque of the engine, when the engine transmits the method. After the flameout, avoid stopping at the compression stroke.

In order to achieve the above, the technical means adopted by the present invention is that the control method for reducing the starting torque of the engine includes the following steps: receiving a flameout signal, detecting engine speed and crank angle, and determining whether the engine speed is lower than a speed. Threshold value; if it is determined that the engine speed is lower than the threshold value of the speed, it is determined whether the crank angle is equal to an angle threshold; if it is determined that the crank angle is equal to the angle threshold, an integrated start generator is controlled to perform the reverse mode, Applying a resistance to the engine, the resistance is a reverse force relative to the direction of rotation of the engine crankshaft, and determining whether the engine speed is lower than or equal to a critical value; and if it is determined that the engine speed is lower than or equal to the critical value, Controlling the integrated starter generator to stop operating.

In summary, the threshold value of the speed threshold and the threshold value of the angle are determined by several measurements and statistics, that is, when the engine speed is lower than the threshold value of the speed, and the crank angle is equal to the threshold value of the angle, the integration is controlled. The starter generator generates resistance to the engine. When the engine is completely stopped by the resistance, the integrated starter generator is stopped. At this time, the engine system is not in the compression stroke, but in the intake stroke, the ignition stroke and the exhaust stroke. Any trip.

When the starter motor is to start the engine, since the engine is in any of the intake stroke, the ignition stroke and the exhaust stroke, the engine chamber does not form a closed space, so the starter motor does not have to overcome the compression as described in the prior art. The gas pressure; thereby, the current and torque required to start the motor are reduced, thereby maintaining the performance of the starting motor.

Referring to Figure 1, the apparatus for performing the method of the present invention includes a manifold pressure sensor 11, a crank position sensor 12 and a controller 13. Referring to the schematic diagram of the engine 20 shown in FIG. 2, the manifold pressure sensor 11 is disposed in the intake pipe 211 to sense the gas pressure in the intake pipe 211. The crank position sensor 12 is disposed outside the end of the crankshaft 27. To generate a square wave signal according to the rotation state of the crankshaft 27. The controller 13 is electrically connected to the manifold pressure sensor 11 and the crank position sensor 12 to receive the pressure value and the square wave signal respectively, wherein the configuration of the engine 20 and the manner of determining the angle of the crankshaft 27 are known techniques, and Let me repeat.

Referring to FIG. 3, the end of the crankshaft 27 of the engine 20 can be coupled to an integrated starter generator 14, which is electrically connected to a battery 15, which is activated during the start of the engine 20. The generator 14 is used as a motor. The motor receives the working power from the battery 15. When the motor is running, the crankshaft 27 can be rotated to drive the piston 24 to move back and forth in the chamber 213, thereby starting the engine 20; when the engine 20 is started Thereafter, the integrated starter generator 14 acts as a generator that can be driven by the operating crankshaft 27 to generate electricity, and the electrical energy generated by the integrated starter generator 14 can be stored in the battery 15. Referring to FIG. 4, the other end of the crankshaft 27 can be further connected to a starter motor 16. The integrated starter generator 14 and the starter motor 16 can simultaneously drive the crankshaft 27 to rotate while the engine 20 is being started.

The controller 13 is provided with a rotational threshold and an angular threshold, wherein the rotational threshold and the angular threshold are determined based on several experimental and statistical results. For example, assume that the controller 13 can define 0 to 180 degrees corresponding to the intake stroke, 180 to 360 degrees corresponding to the compression stroke, 360 to 540 degrees corresponding to the power stroke, and the exhaust stroke corresponding to 540 to 0 degrees; At this time, if the speed threshold is 800 rpm, the preferred angle threshold can be set at any angle between 540 and 660 degrees, and experimentally, the angle threshold is between 570 and 600 degrees. .

Referring to the flow diagram shown in FIG. 5, the controller 13 performs the following steps to achieve the effect of reducing the engine starting torque.

When the vehicle is turned off, the controller 13 receives a flameout signal (101) from the electric door of the vehicle and detects the engine speed and the crank angle. Furthermore, the engine management system (ECU) of the vehicle causes the intake pipe 22 to stop introducing the fuel gas, and the igniter 55 stops acting, so that even in the intake stroke, the fuel gas is not introduced into the chamber 213 of the engine 20, The igniter 55 also does not ignite, so the engine 20 can no longer generate power, thereby reducing the inertial output of the engine 20.

After receiving the flameout signal, the controller 13 determines whether the current engine speed is lower than the speed threshold (102). If not, the controller 13 will determine if the subsequent engine speed is below the speed threshold until it is determined that the engine speed is below the speed threshold; if so, the controller 13 will perform the next step.

The controller 13 determines whether the current crank angle is equal to the angle threshold (103). If not, the controller 13 will determine if the subsequent crank angle is equal to the angular threshold until it is determined that the crank angle is equal to the angular threshold; if so, the controller 13 will perform the next step.

The controller 13 controls the integrated starter generator 14 to perform an inversion mode (104), at which time the integrated starter generator 14 acts as a motor, and the integrated starter generator 14 receives power from the battery 15, the inversion mode It is meant that the integrated starter generator 14 applies a resistance to the engine 20 that is a reverse force with respect to the direction of rotation of the crankshaft 27, thereby slowing the rotation of the crankshaft 27.

While the integrated starter generator 14 performs the reverse mode, the controller 13 determines whether the current engine speed is lower than or equal to a threshold value (105), wherein the threshold value may be 0 (rpm); if not, The controller 13 will continue to determine whether the current engine speed is lower than or equal to the threshold until it is determined that the engine speed is lower than or equal to the threshold; if so, the controller 13 performs the next step.

The controller 13 will control the integrated starter generator 14 to cease actuation, preventing the reverse force applied to the engine 20 from causing the engine 20 to reverse (106).

When the vehicle is turned off, the controller 13 determines that the engine speed is lower than the speed threshold, and the crank angle is equal to the angle threshold. The controller 13 drives the integrated starter generator 14 to operate, and the integrated start generator 14 The crankshaft 27 that is rotating is subjected to resistance to stop the engine 20 from running, avoiding the state in which the engine 20 enters the compression stroke after stopping, but is in any of the intake stroke, the ignition stroke, and the exhaust stroke.

In summary, please refer to FIG. 6, "‧" indicates the state after the conventional engine 20 is turned off, and the engine 20 has a probability of stopping at 85% in the compression stroke; in the present case, "+" indicates the control method of the present invention. The state in which the engine 20 is turned off is stopped. As can be seen from the figure, the engine 20 is not stopped in the compression stroke, but is in any one of the intake stroke, the ignition stroke and the exhaust stroke. Therefore, please refer to FIG. 7 and FIG. As shown in Fig. 8, compared to the conventional engine (as indicated by the thin solid line), when the engine 20 is started again, the current (indicated by the thick solid line) starts the motor to load a lower current, and the engine 20 is started. The required torque is also lower, thereby reducing the energy required to start the engine 20 and maintaining the performance of the starter motor.

11. . . Manifold pressure sensor

12. . . Crankshaft position sensor

13. . . Controller

14. . . Integrated starter generator

15. . . Battery

16. . . start the motor

20. . . engine

twenty one. . . cylinder

211. . . Intake pipe

212. . . exhaust pipe

213. . . Chamber

twenty two. . . Intake valve

220. . . Plug

twenty three. . . Vent

230. . . Plug

twenty four. . . piston

25. . . lighter

26. . . link

27. . . Crankshaft

270. . . Axis

50. . . engine

51. . . cylinder

511. . . Intake pipe

512. . . exhaust pipe

513. . . Chamber

52. . . Intake valve

520. . . Plug

53. . . Vent

530. . . Plug

54. . . piston

55. . . lighter

56. . . link

57. . . Crankshaft

570. . . Axis

Figure 1: Schematic diagram of the control circuit of the present invention.

Figure 2: A partial cross-sectional view of the engine.

Figure 3: Schematic diagram of the connection between the crankshaft and the integrated starter generator.

Figure 4: Schematic diagram of the connection between the crankshaft, the integrated starter generator and the starter motor.

Figure 5 is a schematic flow diagram of the present invention.

Figure 6: Statistical diagram of the crank angle of the present invention and the conventional crankshaft.

Figure 7: Comparison of the starting current of the present invention with conventional ones.

Figure 8: Comparison of the present invention and conventional starting torque.

Figure 9: A partial cross-sectional view of the engine.

Figure 10: Schematic diagram of the sequence in which the engine performs four strokes.

Figure 11: Intake tube pressure - crank angle waveform.

Claims (6)

A control method for reducing engine starting torque includes the steps of: receiving a flameout signal, detecting engine speed and crank angle; determining whether the engine speed is lower than a speed threshold; if it is determined that the engine speed is lower than the speed threshold, Then, it is determined whether the crank angle is equal to an angle threshold, wherein if the crank angle is 0 to 180 degrees, the engine is in the intake stroke, 180 to 360 degrees corresponds to the compression stroke, 360 to 540 degrees corresponds to the power stroke, and 540 to 0 degrees. Corresponding to the exhaust stroke, when the speed threshold is 800 rpm, the angle threshold is any angle between 540 and 660 degrees; if it is judged that the crank angle is equal to the angle threshold, an integrated starter generator is controlled. Performing an inversion mode to apply a resistance to the engine, the resistance being a reverse force with respect to the direction of rotation of the engine crankshaft, and determining whether the engine speed is lower than or equal to a critical value; and if the engine speed is determined to be lower than Or equal to the threshold, controlling the integrated starter generator to stop operating. A control method for reducing engine starting torque as claimed in claim 1, wherein the angle threshold is any angle between 570 degrees and 600 degrees. The control method for reducing the engine starting torque as described in claim 1 or 2, the threshold value being 0 (rpm). The control method for reducing the engine starting torque according to claim 3, if it is determined that the engine speed is not lower than the speed threshold, it is determined whether the subsequent engine speed is lower than the speed threshold, until it is determined that the engine speed is lower than the speed Threshold value. The method for reducing the engine starting torque as described in claim 3, if Judging that the crank angle is not equal to the angle threshold, it is determined whether the subsequent crank angle is equal to the angle threshold until it is determined that the crank angle is equal to the angle threshold. The control method for reducing the engine starting torque according to claim 3, if it is determined that the engine speed is not lower than or equal to the threshold, continuously determines whether the current engine speed is equal to the threshold, until it is determined that the engine speed is lower than or equal to The critical value.