JP2602797B2 - Engine torque fluctuation control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a torque fluctuation control device for an engine, and more particularly, to an engine in which fuel supply is cut off during deceleration operation in a predetermined operation region, when fuel supply is restored. The present invention relates to a device for reducing torque shock.

In (prior art) engines such as automobile, for example, as shown in FIG. 9, the deceleration operation at and the predetermined load T ₀ following areas X at a predetermined rotational speed N ₀ or more, thereby cutting off the supply of fuel As a result, the fuel efficiency may be improved. However, in this engine, the operating state is changed to the above-mentioned state due to a decrease in the number of revolutions indicated by an arrow a or an increase in the load (transition to an acceleration state) indicated by an arrow b. When the fuel supply is returned after leaving the area X,
Due to the sudden restart of combustion, there is a problem that torque shock occurs as indicated by reference numerals a 'and b' in FIG.

To cope with this problem, conventionally, measures have been taken such that the air-fuel ratio at the time of fuel supply return is made lean to restart combustion gently to reduce the torque shock. Japanese Patent Application Laid-Open No. Sho 54-1721 discloses that the air-fuel ratio is made rich at the time of return in order to prevent misfire or engine stall due to fuel shortage or delay in supply at the time of fuel supply return.

On the other hand, according to Japanese Patent Application Laid-Open No. 61-62222, the following device has been proposed as an engine torque fluctuation control device. In other words, this torque fluctuation control device includes a power generator driven by the crankshaft of the engine, and an electric drive device that applies torque to the crankshaft in the rotation direction, and synchronizes these with the torque fluctuation of the crankshaft. When the torque is increased, the power generator is activated, and when the torque is decreased, the electric drive is activated. According to this, when the torque increases, the increase is suppressed by the load (negative torque) of the power generator, and when the torque decreases, the decrease is compensated for by the torque (positive torque) given by the electric drive device. The torque of the crankshaft will be smoothed.

(Problems to be Solved by the Invention) By the way, in the engine in which the supply of fuel is cut off during the deceleration operation in the predetermined operation region as described above,
When the air-fuel ratio is made lean in order to reduce the torque shock at the time of fuel supply return, there is a problem that the NOx content in the exhaust gas increases due to deterioration of the combustion state. Further, when the air-fuel ratio is made rich at the time of return of fuel supply to prevent misfire or engine stall, fuel efficiency deteriorates by that amount, and the effect of improving fuel efficiency performance by shutting off fuel supply at the time of deceleration is impaired. Will be.

Therefore, the present invention focuses on a device for applying a positive torque and a negative torque to an engine output shaft disclosed in Japanese Patent Application Laid-Open No. 61-61222, and shuts off fuel supply during deceleration operation in a predetermined operation region. By applying this type of device to such an engine, the torque at the time of fuel supply return is appropriately controlled to reduce the torque shock without deteriorating fuel efficiency and increasing NOx emissions With the goal.

(Means for Solving the Problems) In order to achieve the above object, an engine torque fluctuation control device according to the present invention is characterized in that it is configured as follows.

That is, in an engine in which the supply of fuel is cut off during deceleration operation in a predetermined operation region, a positive torque applying means for applying a positive torque to an engine output shaft, a negative torque applying means for applying a negative torque, Control means for operating the means at a predetermined timing when fuel supply is restored. Specifically, when the fuel supply is returned from the fuel supply cutoff state, immediately before the return, the control means first activates the positive torque applying means,
Next, the negative torque applying means is operated, and the fuel supply is restored while the negative torque applying means is operating.

(Operation) According to the above configuration, while the fuel supply is interrupted, a negative torque acts on the engine output shaft. However, the positive torque applying means operates immediately before the return of the fuel supply, so that the engine output shaft has a negative effect. The negative torque is reduced, or the state shifts to a relatively small positive torque. When a large positive torque acts on the engine output shaft as a torque shock due to a sudden restart of combustion at the time of fuel supply return, the positive torque is suppressed because the negative torque applying means is operating. .

In other words, the torque immediately before the occurrence of the torque shock generated at the time of the return of the fuel supply increases, and the torque shock decreases. Thus, the torque shock at the time of the return of the fuel supply is reduced, and the torque of the engine output shaft becomes smooth. Will change.

(Examples) Hereinafter, examples of the present invention will be described.

First, the mechanical structure of the torque control device constituting this embodiment will be described with reference to FIG. 1. This device 1 utilizes a flywheel 4 attached to a crankshaft 3 protruding from an end face of an engine body 2. A rotating field pole 5 provided on an outer peripheral portion of the flywheel 4, and
It has a field coil 6 and a stator coil 7 respectively arranged on the outer periphery. As shown in FIG. 2, the rotating field poles 5 are integrally formed on the outer peripheral portion of the flywheel 4 at fixed intervals, and have a number of claws 8a facing the engine body 2 side.
8a, a second pole core 9 having a number of claws 9a... 9a located between the claws 8a. , 9 and a non-magnetic ring 10 which is connected to the inside of the tips of the claws 8a ... 8a, 9a ... 9a. Also,
The field coil 6 has a configuration in which a conductive wire is wound around a field core 12 fixed to an end face of the engine body 2 via an aluminum plate 11 for blocking a magnetic field. The flywheel 4 is accommodated in a recess 4a provided on the surface of the outer periphery of the flywheel 4 on the engine body 2 side so as to be close to and opposed to the inner periphery of the second pole cores 8, 9). Here, a minute gap is provided between the opposing surfaces of the field core 12 and the flywheel 4 and the rotating field pole 5. Further, the stator coil 7
Is a ring-shaped stator core made of a laminate of many steel plates
13 is a configuration in which a conductive wire is wound around the inner peripheral surface of the rotating field pole 5.
The stator core so as to be close to and opposed to the outer peripheral surface of the stator core.
13 is fixed to a ring-shaped frame 15 sandwiched between the engine body 2 and the clutch housing 14. As shown in FIG. 3, a plurality of slits 13a are provided on the inner peripheral side of the stator core 13 at regular intervals.
A three-phase coil is formed by winding a conducting wire in a three-phase manner around 13a.

As shown in FIG. 1, a clutch 17 for connecting and disconnecting the crankshaft 3 and the transmission input shaft 16 is disposed on the flywheel 4 on the side opposite to the engine body 2. On both sides of the outer peripheral portion of the stator coil 7, cooling water pipes 18, which cool these coils 6, 7 respectively, are provided.
19, 19 are provided.

Next, the control system of this embodiment will be described with reference to FIG.
It has a field controller 22 for controlling the energization of the field coil 6 and an inverter 23 for controlling the energization of the stator coil 7. When the ignition switch 24 is turned on, the control unit 21 directly from the battery 25 The field controller 22 and the inverter 23 are supplied with power via the relay 26, respectively.

The inverter 23 is connected to a battery 25 as shown in FIG.
Current control circuits 23 ₁ , 23 ₂ , 23 ₃ between the positive side and the negative side of
The provided with these circuits 23 _1, 23 _2, a total of six in each two increments series 23 ₃ established the switching element S ₁ to S _6,
And the switching of the battery 25 in parallel with each of the switching elements S _{1 to} S _6.
In the configuration set up a diode D ₁ to D ₆ for passing a current from the side in the + direction, the three-phase in the stator coil 7 between each two switching elements in each of circuits 23 _1, 32 _2, 23 ₃ first eggplant, second, third coil 7 _1, 7 _2, 7 ₃ are respectively connected. The switching elements S _{1 to} S ₆ are turned on and off intermittently by a pulse signal to supply a three-phase alternating current to the stator coil 7.
At this time, when the field coil 6 shown in FIG. 4 is energized and the rotating field pole 5 is excited, a magnetic force acts on the rotating field pole 5 by the rotating magnetic field formed by the three-phase alternating current of the stator coil 7. Thus, a positive torque for driving the crankshaft 3 in the direction of its rotation is applied. That is, the torque control device 1 operates as an AC motor. When the rotating field pole 5 excited by the field coil 6 rotates while the switching elements S _{1 to} S _{6 of the} inverter 23 are OFF,
First to third coil 7 ₁ of the stator coil 7, 7 _2, 7 ₃ induced electromotive force is generated, which diodes D ₁ ~ inverters 23
Is rectified by being supplied to the battery 25 side by D _6, the torque control device 1 is adapted to operate as an alternator to charge the battery 25.

On the other hand, as shown in FIG. 4, the control unit 21 outputs a crank angle signal a output from a crank angle sensor 27 for detecting a rotation angle (crank angle) of the crank shaft 3 from a reference position via an amplifier 28. And a load signal b from a load sensor 30 for detecting an engine load based on the intake negative pressure in the intake passage 29 of the engine. The control unit 21 controls the inverter 23 according to the engine speed calculated based on the crank angle signal a and the engine load indicated by the load signal b.
By outputting a control signal c ₁ to c ₆ to each of the switching elements S ₁ to S ₆ of which is a torque control device 1 so as to operate as or alternator as an AC motor according to the operating state of the engine. During operation as an AC motor, the switching elements S _{1 to} S ₆ of the inverter 23 are turned on in synchronization with the crank angle indicated by the signal a so that a positive torque is effectively applied to the crankshaft 3. It is turned off, and the control of energization of the field coil 6 by the field controller 22 is performed by a signal d.

Further, the control unit 21 performs fuel supply control to the engine in addition to the control of the torque control device 1 as described above. That is, based on the engine speed calculated based on the crank angle signal a and the intake air amount indicated by the signal e from the air flow meter 31 provided upstream of the intake passage 29, the fuel injection nozzles 32.
, And outputs a fuel control signal f to each of the nozzles 32... 32 so as to achieve the injection amount. Then, the signal a, the engine speed and the load and which is detected on the basis of b, at a predetermined rotational speed N ₀ over the operating state of the engine is shown in Figure 6, a predetermined load T ₀ following the fuel cut-off region X When it is detected that fuel belongs, the fuel injection from the fuel injection nozzles 32... 32 is stopped.

Next, the operation of this embodiment at the time of fuel supply return will be described with reference to the flowchart of FIG.

First, the control unit 21 detects the engine speed N and the engine load T based on the signals a and b in steps S ₁ and S ₂ of the flowchart. Then, in steps S ₃ and S ₄ ,
The number of revolutions N is greater than a first reference number of revolutions N ₀ ′ that is greater than the lower limit number of revolutions N ₀ of the fuel cut-off area X by a predetermined number of revolutions n, and the load T is greater than the upper limit load T _{0 of the} area X. When it is determined that the load is smaller than the first reference load T ₀ ′ which is smaller by the load t, that is, when the operation state is the complete deceleration region in the fuel cutoff region X in FIG.
When in the X ₀ is a torque control device 1 shown in FIG. 4 in step S ₅ is operated as the alternator, and control the inverter 23 so as not to perform the operation as an AC motor signal c ₁ to c ₆ output I do. That is, in this fully decelerated region X _0, to increase the deceleration by the negative torque (power resistor) due to the operation of the alternator is to recover energy by the operation.

Next, from this state, the engine speed N gradually decreases as shown by an arrow a in FIG.
N ₀ ′, or when the engine load T shifts to the acceleration state as indicated by the arrow b, the engine load T is reduced to the first reference load
Becomes greater than T ₀ ', the control unit 21 steps from step S ₆ or Step S ₄ from the step S ₃
Run the S _7, a minute amount of rotation speed N is higher than the lower limit engine speed N ₀ delta
It is determined whether or not the load T is larger than a second reference load N ₀ ″ which is larger by n or whether the load T is smaller than a second reference load T ₀ ″ which is smaller than the upper limit load T ₀ by a small amount Δt. And
When N> N ₀ ″ or T <T ₀ ″, that is, when the operating state belongs to the first transient region X ₁ indicated by the solid hatching in FIG. 6, the torque control device 1 is used as an AC motor in step S _8. is operated, it outputs the control signal c ₁ to c ₆ so as not to perform the operation as an alternator. That is, when the return to the fuel supply area Y is approaching, first, a positive torque is applied to the crankshaft 3 by operating the AC motor.

When the engine speed N further decreases and becomes smaller than the second reference speed N ₀ ″, or when the engine load T further increases and becomes larger than the second reference load T ₀ ″,
That is, when the operation state has entered the second transition region X ₂ which close proximity to the fuel feed region Y shown at point hatching in FIG. 6 is a control unit 21, step S from step S ₆ or step S ₇ Step ₉ is performed to operate the torque control device 1 again as an alternator and output the control signals c _{1 to} c ₆ so as not to operate as an AC motor. Then, the fuel supply is restored in this state.

Accordingly, in both cases of the return of the fuel supply due to the decrease of the engine speed N indicated by the arrow a and the return of the fuel supply due to the increase of the engine load T accompanying the shift to the acceleration state, the AC immediately before the return is obtained. A positive torque is applied to the crankshaft 3 by the motor, and then a negative torque is applied by the alternator, and the fuel supply is restored in a state where the negative torque is applied. As a result, as shown in FIG. 8, the state of the torque of the crankshaft 3 is such that the torque immediately before the occurrence of the torque shocks a 'and b' at the time of fuel supply return increases, and the torque shocks a 'and b' Is suppressed, and the torque changes smoothly.

At the time of the transition to the acceleration state, the torque control device 1 is operated as an AC motor and is not operated as an alternator when the fuel supply is restored. Can be improved. When the battery 25 is in an overcharged state,
Sixth torque control device 1 in the full deceleration range X ₀ shown in FIG.
It is desirable to control not to operate not only as an AC motor but also as an alternator. This control
This is performed by stopping the energization of the field coil 6 shown in FIG.

(Effects of the Invention) As described above, according to the present invention, in an engine in which the supply of fuel is cut off during deceleration operation in a predetermined operation range, first, when the fuel supply is restored, a positive torque is applied to the engine output shaft. And then give a negative torque, and the fuel supply was restored in the state where the negative torque was given.
As in the conventional case, the return of the fuel supply is performed satisfactorily without increasing the NOx emission amount by making the air-fuel ratio lean at the time of return, or deteriorating the fuel efficiency performance by making the air-fuel ratio rich. The torque shock is reduced.

[Brief description of the drawings]

1 to 8 show an embodiment of the present invention. FIGS. 1 and 2 are a longitudinal sectional view and a perspective view of a torque control device, FIG. 3 is a schematic diagram of a stator coil in the device, and FIG. FIG. 5 is a circuit diagram showing the configuration of the inverter in FIG. 4, FIG. 6 is a map showing a fuel cut-off region and a torque control region, and FIG. 7 is a flowchart showing an operation of the torque control. FIG. 8 is a diagram showing the change over time of the engine speed at the time of fuel supply return showing the operation. FIG. 9 is a map showing a fuel cut-off area used for explaining a conventional problem,
FIG. 10 is a diagram showing the change over time of the engine speed at the time of fuel supply return showing the problem. 1. Torque control device, 3. Engine output shaft (crank shaft), 5, 6, 7 ... Positive torque applying means, negative torque applying means (rotating field pole, field coil, stator coil), 21 ... Control Means (control unit).

Claims (1)

(57) [Claims] 1. An engine in which the supply of fuel is cut off during a deceleration operation in a predetermined operation region, comprising a positive torque applying means for applying a positive torque to an engine output shaft, and a negative torque applying means for applying a negative torque. A torque fluctuation control device for an engine, further comprising control means for operating the positive torque applying means immediately before returning fuel supply and then returning fuel supply in a state where the negative torque applying means is operated. .