JP2002305807A - Engine stop control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent resonance of an engine of a car with a car body when the engine stops, to enhance the durability of an engine-mounted part, and to suppress vibration of the car body. SOLUTION: This engine stop control device is provided with a motor 2 for giving counter torque to an engine when the engine stops, a means 15 of detecting the rotational speed of the engine, and a motor control means 14 for calculate necessary counter torque on the basis of the detected rotational speed of the engine, and controlling the motor so as to generate the counter torque.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine stop control device, and more particularly to a technique for suppressing vibration caused by resonance with a vehicle body when the engine is stopped in an idling stop or a hybrid vehicle.

[0002]

2. Description of the Related Art In recent years, an idling stop device for stopping an engine when waiting for a traffic light has been proposed from the viewpoint of environmental pollution and energy saving. For the same purpose,
Hybrid vehicles equipped with an electric motor as a drive source in addition to the engine have been developed.

[0003]

In these devices and vehicles, the engine is stopped more frequently than in a normal vehicle. Since the frequency of the engine vibration generated at this time frequently passes through the resonance point of the vehicle body (or the vehicle), it is necessary to strengthen the engine mount portion and to devise a way to avoid the resonance point of the vehicle body as much as possible.

FIG. 8 shows how the engine speed changes when the engine is stopped. As shown in the figure, when the fuel supply is stopped (fuel cut), the engine (including the flywheel) rotates only by inertial force, and the engine rotation gradually decreases due to mechanical loss of the engine. Go. And in the extremely low rotation range (20 in the example shown)
(Around 0 rpm), the engine vibration resonates with the vehicle body,
The engine and the vehicle body are greatly shaken, and a heavy load is applied to the engine mount portion, and the occupants in the vehicle feel extremely uncomfortable. Therefore, it is desirable to positively control the stop of the engine so that the engine vibration of this resonance frequency does not appear or pass through the resonance point as soon as possible.

In view of the above circumstances, the present invention has been devised. It is an object of the present invention to avoid resonance with the vehicle body when the engine is stopped, improve the durability of the engine mount, and effectively suppress the vibration of the vehicle body. An object of the present invention is to provide an engine stop control device.

[0006]

An engine stop control device according to the present invention includes a motor for applying a reverse torque to the engine when the engine is stopped, a means for detecting a rotational speed of the engine, and a detected engine. Motor control means for calculating a necessary reverse torque based on the rotation speed and controlling the motor so as to generate the reverse torque.

An engine stop control device according to the present invention provides a motor for applying a reverse torque to the engine when the engine is stopped, means for detecting the crank angle of the engine, and means for detecting the rotational speed of the engine. Means and a motor control means for calculating a necessary reverse torque based on the detected crank angle and engine rotation speed and controlling the motor so as to generate the reverse torque.

Further, the engine stop control device according to the present invention provides a motor for applying a reverse torque to the engine when the engine is stopped, a means for detecting the rotation speed of the engine, and a control unit based on the detected engine rotation speed. And a motor control means for controlling the motor so that the reverse torque is generated by calculating a required reverse torque based on the calculated rotational change. .

Here, the calculation of the reverse torque in the motor control means may be performed by an average value reference method.

[0010] The calculation of the reverse torque in the motor control means may be performed by a maximum point reference method.

The calculation of the reverse torque by the motor control means may be performed by further adding a predetermined reverse torque value to the reverse torque value calculated by the highest point reference method.

The calculation of the reverse torque in the motor control means may be performed according to a map stored in the motor control means in advance.

[0013]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 7 shows a vehicle to which the present invention is applied. This vehicle is a hybrid vehicle of an FR drive system and includes a rotating electric machine (motor generator) 2 as a second drive source in addition to an engine 1 as a first drive source. A rotating electric machine (motor generator) 2, a clutch 3, and a transmission 4 are provided in series along the power transmission direction from the engine 1.

The engine 1 is an internal combustion engine that generates driving force by burning fuel, and is a diesel engine here. The rotating electric machine 2 is connected to a battery 6 via an inverter 5, and functions as a motor for supplying a driving force to the outside when power is supplied from the battery 6, and is driven from the outside during braking or the like. And functions as a generator for storing electricity in the battery 6. The rotating electric machine 2 includes a rotor 2a and a stator 2b. The rotor 2a is fixed to an output shaft 1a of the engine 1, and the stator 2b is
Is fixed to the casing 2c. Output shaft 1 of engine 1
a is also the input shaft of the clutch 3. Here, the clutch 3 is a manual dry single-plate clutch. Clutch 3
The output shaft 3a is also an input shaft of the transmission 4. A drive wheel 10 is connected to an output shaft (not shown) of the transmission 4 via a propeller shaft 7, a differential 8, and an axle 9.

An engine control unit 11, a motor control unit 12, a battery control unit 13, and a vehicle control unit (hereinafter referred to as EC)
U) 14 are provided. The engine control unit 11 is for electronically controlling the engine 1, reads a crank pulse from a crank angle sensor 15 provided in the engine 1, and calculates a current crank angle (rotation phase) and a rotation speed of the engine 1. . The crank angle signal and the rotation speed signal are also sent to the vehicle control unit 14. Motor control unit 12
Receives a signal for controlling the rotating electric machine 2 from the ECU 14, and controls the inverter 5 to match the signal.
That is, the rotating electric machine 2 is substantially controlled by the ECU 14. The control signal sent from the ECU 14 includes a torque command signal and the like. The battery control unit 13 receives information such as the charged amount from the battery 6 and outputs the information to the ECU 14.

The ECU 14 reads information on the current gear position and the vehicle speed from the gear position sensor 16 and the vehicle speed sensor 17 provided in the transmission 4, and reads information on the current accelerator opening and clutch position from the accelerator sensor 18 and the clutch sensor 19. Read information.

The engine stop control device according to the present invention is realized by the above configuration as follows.

FIG. 9 shows another state when the engine is stopped. The horizontal axis is time, and the vertical axis is the engine speed at the top and the friction torque of the engine at the bottom. As shown in the figure, for example, when the fuel supply is stopped (fuel cut) to an engine that is running at idle, the engine rotates with inertia force with rotation fluctuation or torque fluctuation,
In addition, receiving the friction, the motor gradually decelerates and stops rotating.
In the friction torque diagram, f1 is the friction torque due to the mechanical loss, and f2 is the friction torque due to the compression. Cylinder compression,
The friction f2 corresponding to the compression oscillates with the expansion (see FIG. 8), thereby causing rotation fluctuation or torque fluctuation when the engine is stopped. Then, a large rotation fluctuation occurs in an extremely low speed range, which overlaps with the resonance point of the vehicle body and causes a large body swing.

In order to suppress such resonance when the engine is stopped, the present invention controls the rotating electric machine 2 to apply a reverse torque to the engine so as to stop the engine as soon as possible or to reduce fluctuations in engine rotation or torque. Motor control). By doing so, it is possible to avoid vibration of the engine such that the vehicle passes through the resonance point early or becomes a resonance point with the vehicle body, and the swing of the vehicle body can be prevented. Here, since the rotating electric machine 2 is used as a motor, the “rotating electric machine” will hereinafter be referred to as “motor” in principle.

Here, as shown in FIG. 6, the rotation direction of the engine is positive in the counterclockwise direction (+). When the engine is stopped, the magnitude of the rotation speed in the + direction is a direction in which the magnitude gradually decreases. On the other hand, the reverse torque given from the motor 2 to the engine 1 is positive (+) in the clockwise direction opposite to the rotation direction of the engine.

First, a first method is a method of calculating a necessary reverse torque based on the rotation speed of the engine and controlling the motor 2 so as to generate the reverse torque. That is, EC
In U14, a two-dimensional map that defines the relationship between the engine speed and the reverse torque (motor reverse torque) generated by the motor 2 as shown in FIG. 1 is stored in advance, and after fuel cut, the map is always stored according to this map. In this method, a reverse torque corresponding to the engine speed is calculated from a map and is generated from the motor 2. In this map, the reverse torque increases as the engine speed increases. The map diagram may be a straight line as shown by a1, but may be a quadratic curve or the like as shown by a2. This method is based on the idea that the higher the rotation of the engine, the higher the torque generated. Therefore, a large reverse torque is applied to suppress the torque fluctuation of the engine and stop the engine early.

The second method is to calculate a required reverse torque based on the crank angle and the engine speed of the engine,
This is a method of controlling the motor 2 so as to generate the reverse torque. That is, a map as shown in FIG.
14 is stored, and after the fuel cut, the reverse torque is always calculated according to this map, and the reverse torque is generated from the motor 2 in the same manner as described above. However, this map is a three-dimensional map for calculating the reverse torque based on the crank angle of the engine and the engine speed. The illustrated example is for a four-cylinder engine, and the map diagram is a sine curve. The maximum value appears before the crank angles of 90 ° and 270 °. At this angle, the maximum value of the engine rotation speed or the positive torque associated with the expansion stroke occurs, so that a large reverse torque should be applied accordingly. It is. In the illustrated example, the same sinusoidal curve is shifted toward the reverse torque increasing side as the engine speed increases. The maximum value is a crank angle of 90.
°, 270 ° does not appear exactly, but appears in front of it,
This is because the piston speed is higher before the piston than at the top dead center and receives a strong compression reaction force.

According to this, when the predetermined cylinder is in the expansion stroke and the engine speed is increased, a relatively large reverse torque is applied. Conversely, when the predetermined cylinder is in the compression stroke and the engine speed is decreased, a relatively small reverse torque is applied. It is possible to apply torque, to promote a decrease in engine speed and to suppress engine speed fluctuations or torque fluctuations. In particular, since the control for finely increasing or decreasing the reverse torque in accordance with the rotation fluctuation or torque fluctuation of the engine is performed, it can be said that the accuracy is higher and more effective than the first method.

As a modified example of this, there is a method using a map shown in FIG. In this map, the amplitude of the sinusoidal curve is increased or decreased for each engine speed, and sometimes a negative reverse torque (in a direction in which the engine is accelerated) is also applied. This makes it possible to cope with high rotation and high torque, and there is a possibility that a high effect can be obtained.

Next, a third method is to calculate a rotation fluctuation per unit time based on the engine rotation speed, calculate a necessary reverse torque based on the calculated rotation fluctuation, and generate the reverse torque. This is a method of controlling the motor 2 to perform the operation. That is, since the engine speed fluctuates as shown in FIG. 4, the speed fluctuation ΔN / Δ per unit time Δt.
t is constantly calculated, a reverse torque is calculated from the rotation fluctuation ΔN / Δt according to the map shown in FIG. The map is stored in the ECU 14 in advance. The map is a two-dimensional map for calculating the reverse torque based on the rotation fluctuation ΔN / Δt, and the rotation fluctuation ΔN / Δt =
0, a larger positive reverse torque is applied as the rotation fluctuation ΔN / Δt increases, and the rotation fluctuation ΔN / Δt
The smaller the is, the larger the reverse torque is applied in the negative direction. In the illustrated example, the diagram is a straight line, but may be a curve. In the example of FIG. 4, since the engine rotation is depressed and ΔN is negative, ΔN / Δt is also negative, and a negative reverse torque (that is, a torque that accelerates the engine) is given.

According to this, when the predetermined cylinder is in the expansion stroke and the engine speed increases, a positive reverse torque for suppressing this is applied, and conversely, the predetermined cylinder is in the compression stroke and the engine speed drops. In some cases, a negative reverse torque that suppresses this can be given, and the rotation fluctuation or torque fluctuation of the engine can be suppressed. This method also
Since the control for finely increasing or decreasing the reverse torque is performed in accordance with the rotation fluctuation of the engine, it can be said that the accuracy is higher and more effective than the first method. However, since a negative reverse torque is applied to the negative rotation fluctuation ΔN / Δt, the method does not work in the direction of stopping the engine, and rather, it can be said that this method emphasizes the rotation fluctuation suppression. However, depending on how the standard is set, the engine can be operated in the direction of stopping the engine.

Here, comparing the first to third methods,
In the first and second methods, the reverse torque is determined uniformly according to the engine speed and the crank angle, whereas in the third method, the reverse torque is measured so as to eliminate this while measuring the actual engine rotation fluctuation. Feedback control.

Next, a method of calculating the reverse torque, specifically, how to determine the value of the reverse torque on the map will be described.

The first method is a method based on the average value method. As shown in FIG. 9, the friction torque of the engine is the friction torque f1 due to the mechanical loss.
And a friction torque f2 due to compression. The former hardly increases or decreases, whereas the latter greatly fluctuates with the compression and expansion of the engine. Therefore, when this is averaged, an average curve as shown by A is obtained. In the mean value method, the value of the reverse torque is determined on the basis of the mean value or the mean curve thus obtained.

For example, in an actual machine test or the like, the actual friction torque (ie, the curve of f1 + f2 in the illustrated example) and the average value thereof are checked for each rotation speed and crank angle, and for each rotation speed and crank angle, The difference between the actual friction torque and the average value is determined, and a value that makes the difference zero is defined as a reverse torque value. In the example of FIG. 9, h1 and h2 correspond to this. As for h1, since the actual friction torque is smaller than the average value (the engine is hard to stop), a positive value equal to the difference between the actual value and the average value is set as the reverse torque value, and the engine is actively stopped. As well as torque fluctuation. On the other hand, h2
For, since the actual friction torque is larger than the average value (the engine is easily stopped), a negative value equal to the difference between the actual value and the average value is used as the reverse torque value to eliminate torque fluctuation. . In this case, setting the value of the reverse torque to 0 is advantageous for promoting the engine stop. However, in this case, a torque variation is likely to appear, so a small negative value may be used as the reverse torque value as a compromise.

Next, the second method is a method based on the highest point reference method. This determines the value of the reverse torque with reference to the highest point B of the friction torque of the engine, as shown in FIG.

For example, in an actual machine test or the like, the maximum value of the actual friction torque is checked for each rotation speed, and the difference between the maximum value and the actual friction torque is calculated for each rotation speed and crank angle. The value that makes the difference zero is the reverse torque value. In the example of FIG. 9, s1 corresponds to this. In this case, except for the crank angle at which the actual friction torque is maximized, a positive value that always cancels the torque fluctuation is the reverse torque value. That is, the control of the engine is in a direction of stopping the engine more actively than in the first method. This method can be said to be a method of generating a reverse torque so as to absorb a portion where the compression torque f2 escapes.

Next, a third method is to add a predetermined reverse torque value to the reverse torque value calculated by the highest point reference method. As shown in FIG. 9, this is based on the assumption that the friction torque C is higher than the highest point B of the friction torque of the engine, and the value of the reverse torque is determined based on this.

For example, in an actual machine test or the like, a maximum value B of the actual friction torque is checked for each rotation speed, and a virtual friction torque C in which the predetermined value s2 is added to the maximum value B is set. . Then, a difference between the virtual value and the actual friction torque is obtained for each rotation speed and crank angle, and a value that makes the difference zero is set as a value of the reverse torque. That is, s1 + s2 corresponds to this. in this case,
At all crank angles, a surplus positive value is added in addition to a positive value sufficient to cancel the torque fluctuation, and becomes a reverse torque value. In the control of the engine, the engine is more actively stopped than in the second method.

Here, comparing the first to third methods, the reverse torque value increases as the first, second, and third methods proceed, and the power consumption by the motor increases accordingly.
Therefore, the first method is most advantageous from the viewpoint of suppressing power consumption. On the other hand, if it is desired to stop the engine early, the third method is most advantageous. In practice, it will be considered which method to take in consideration of these balances.

In the above description, when a positive reverse torque is applied from the rotating electric machine 2 to the engine 1, regenerative braking is performed by using the rotating electric machine 2 as a generator instead of electrically rotating the rotating electric machine 2 in reverse. It is also possible to do. In this case, the battery 6 can be charged, and the power consumption is further prevented.

As described above, according to the present invention, fluctuations in engine rotation and torque when the engine is stopped are suppressed, and the engine can be stopped quickly and smoothly. Therefore, resonance with the vehicle body when the engine is stopped is avoided. It is possible to improve the durability of the mount portion and effectively suppress the vibration of the vehicle body.

As a conventional technique, there is a method of speeding up the engine stop by using an intake shutter. However, the present invention has an advantage that the cost of parts can be reduced in that control is performed without using the intake shutter.

Various other embodiments of the present invention are conceivable. For example, in the above embodiment, the calculation of the reverse torque is performed using a map, but the calculation may be performed by numerical calculation according to a predetermined program. Further, the present invention can be applied to a vehicle which is not a hybrid vehicle and has an idling stop device.

[0041]

In summary, according to the present invention, there is provided an excellent effect that resonance with the vehicle body can be avoided when the engine is stopped, durability of the engine mount portion can be improved, and vibration of the vehicle body can be effectively suppressed. Be demonstrated.

[Brief description of the drawings]

FIG. 1 is a map according to a first engine stop control method.

FIG. 2 is a map according to a second engine stop control method.

FIG. 3 is another map according to a second engine stop control method.

FIG. 4 is a graph showing a method of obtaining rotation fluctuation per unit time according to a third engine stop control method.

FIG. 5 is a map according to a third engine stop control method.

FIG. 6 is a diagram showing an engine rotation direction and a direction of a motor reverse torque.

FIG. 7 is a configuration diagram of a vehicle to which the present invention is applied.

FIG. 8 is a diagram showing a state of a drop in engine rotation when the engine is stopped.

FIG. 9 is a diagram for mainly explaining a method of calculating a motor reverse torque.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Rotating electric machine 5 Inverter 6 Battery 12 Motor control unit 14 Vehicle control unit 15 Crank angle sensor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F02D 45/00 362 B60K 9/00 E (72) Inventor: Akira Hotta Isuzu Motors, Fujisawa City, Kanagawa Prefecture Fujisawa Plant, Inc. (72) Inventor Kiyoshi Takeuchi, 8 Dosana, Fujisawa City, Kanagawa Prefecture Isuzu Motors Fujisawa Plant, Inc. 72) Inventor Takahiro Okamoto 6-26-1, Minamioi, Shinagawa-ku, Tokyo Isuzu Motor Co., Ltd. F-term (reference) 3G084 BA03 CA07 DA39 FA34 FA38 3G093 AA07 BA33 DA01 DA13 DA14 EB08 EC01 5H115 PA05 PC06 PG04 PI16 PI24 PI29 PO02 PO06 PO09 PU08 PU23 PU25 PV09 QE20 QI04 QN03 RB21 RE01 RE20 TE02 TE10

Claims (7)

[Claims] A motor for applying a reverse torque to the engine when the engine is stopped; a means for detecting a rotation speed of the engine; and a required reverse torque calculated based on the detected engine rotation speed. An engine stop control device comprising: a motor control unit that controls the motor so that reverse torque is generated. 2. A motor for applying a reverse torque to the engine when the engine is stopped, means for detecting the crank angle of the engine, means for detecting the rotational speed of the engine, An engine stop control device comprising: a motor control unit that calculates a required reverse torque based on an engine rotation speed and controls the motor to generate the reverse torque. 3. A motor for applying a reverse torque to the engine when the engine is stopped, a means for detecting a rotational speed of the engine, and a rotational fluctuation per unit time is calculated based on the detected engine rotational speed. And a motor control means for calculating a required reverse torque based on the calculated rotation fluctuation and controlling the motor to generate the reverse torque. 4. The engine stop control device according to claim 1, wherein the calculation of the reverse torque in the motor control means is performed by an average value reference method. 5. The engine stop control device according to claim 1, wherein the calculation of the reverse torque in the motor control means is performed by a maximum point reference method. 6. The engine stop according to claim 1, wherein the calculation of the reverse torque by the motor control means is performed by further adding a predetermined reverse torque value to the reverse torque value calculated by the highest point reference method. Control device. 7. The engine stop control device according to claim 1, wherein the calculation of the reverse torque in the motor control means is performed according to a map stored in the motor control means in advance.