JPH05263702A - Fuel controller of engine - Google Patents

Abstract

PURPOSE:To prevent resonance phenomenon by restricting a number of torque generation cylinders in an engine rotation range corresponding to the resonance point of a torsional damper. CONSTITUTION:A torque converter 44 is connected to the end part of a crank shaft 42 via a torsional damper 43, and torque is generated from each cylinder in an engine 41. When the real number of resolution of the engine is detected by a sensor 46, it is judged by a judgement means 47 whether the sensor detection value is in a rotational range of a specified width including the engine speed corresponding to the resonance point of rotational vibration generated by the torsional damper 43. The number of cylinders in which the torque is generated is restricted by a restricting means 48 when it is judged that the sensor detection value is in the rotational range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control device for an engine having an automatic transmission, and more particularly to a fuel control device having a torsional damper between a torque converter and a crankshaft.

[0002]

2. Description of the Related Art In an automatic transmission, a crankshaft is connected to a torque converter, which increases engine torque and absorbs torque fluctuations to some extent.

By the way, in connecting the crankshaft and the torque converter, the purpose is to absorb shock.
For example, as disclosed in Japanese Utility Model Laid-Open No. 54-69289, a torsion spring is provided between the crank end (the end of the crank shaft) and the torque converter. By deforming the torsion spring by the impact of the torque, the impact is prevented from directly acting on the torque converter.

On the other hand, the torsion spring twisted by the impact does not keep twisting, but tries to restore the original state and twists the crankshaft and the torque converter back. The elastic energy stored in the torsion spring causes torsional vibration (rotational vibration) between the crankshaft and the torque converter.

Therefore, by providing a rotational vibration damping element such as a viscous coupling in parallel with the torsion spring, resistance is imparted to the torsion and twisting back of the torsion spring to damp the rotational vibration.

[0006]

When a rotary vibration system is constructed by connecting a torque converter to a crankshaft via a torsion spring, it has an inherent resonance point.

By the way, the combined torque acting on the crankshaft due to the explosion pressure of each cylinder has a harmonics component acting as an exciting force (rotation 2 in a 4-cylinder engine).
There is a secondary component, a rotational third component in a 6-cylinder engine, and the frequency of the exciting force (exciting frequency) increases in proportion to the engine speed.

Therefore, in the engine rotation range where the vibration frequency is equal to or close to the frequency at the resonance point, the torque fluctuation of the engine acts as a vibration force to cause a resonance phenomenon.

Normally, the engine speed range where the resonance phenomenon occurs is set to a range lower than the idle speed,
Although the resonance phenomenon does not occur after the engine is started, it always passes through this region when the engine is started (even when the engine is stopped), so that the resonance phenomenon causes large torque fluctuation and rotation fluctuation as shown in FIG. Of.

Therefore, according to the present invention, by limiting the number of torque generating cylinders in the engine rotation range corresponding to the resonance point,
The purpose is to avoid the resonance phenomenon.

[0011]

According to a first aspect of the present invention, as shown in FIG. 1, a torque converter 44 is connected to an end of a crankshaft 42 via a torsional damper 43, while torque is generated for each cylinder. In the engine 41 to be operated, the sensor 46 for detecting the actual engine speed and the sensor detection value are in a rotation range of a predetermined width including the engine speed corresponding to the resonance point of the rotational vibration generated by the torsional damper 43. Means 47 for determining whether
And a means 48 for limiting the number of cylinders in which torque is generated when there is a sensor detection value in this rotation range.

As shown in FIG. 2, the second aspect of the present invention is an engine 41 that produces torque for each cylinder while connecting a torque converter 44 to an end of a crankshaft 42 via a torsional damper 43. 46 for detecting the engine speed of the engine, and means for determining whether or not the sensor detection value is in a rotation range of a predetermined width including the engine speed corresponding to the resonance point of the rotational vibration generated by the torsional damper 43. 47, means 48 for limiting the number of cylinders in which torque is generated when there is a sensor detection value in this rotation range, and means 49 for increasing the generated torque per cylinder when there is a sensor detection value in this rotation range. And.

[0013]

In the harmonic component of the engine torque, which acts as an exciting force on the rotational vibration caused by the torsion and the twisting back of the torsional damper 43, the frequency of the exciting force increases in proportion to the engine speed.

In this case, when the engine rotation speed becomes equal to or close to the engine rotation speed corresponding to the resonance point, the rotation fluctuation due to resonance becomes large in the vicinity of this rotation speed.

On the other hand, according to the present invention, when the number of cylinders in which torque is generated is limited in the rotation range of a predetermined width including the engine speed corresponding to the resonance point, the vibration frequency is the same when all cylinders burn. Then it is displaced. Since the vibration frequency corresponds to the number of cylinders in which torque is generated, if the number of cylinders is limited, the vibration frequency can be switched to the smaller vibration frequency.

As a result, the vibration frequency and the frequency at the resonance point do not coincide with each other and do not approach each other, so that the resonance phenomenon does not occur.

On the other hand, when the engine speed range corresponding to the resonance point is set to a range smaller than the idle speed,
Due to the limitation of the number of cylinders in which torque is generated, the overall torque is reduced, and the engine rotation becomes unstable.

In this case, when the torque generated per cylinder is increased in the second aspect of the invention to prevent a decrease in overall torque, a drop in rotation is avoided.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, FIGS. 3 and 4 show a device in which a torque converter 2 is connected to a crank end 1 via a torsional damper 4 and a rotational vibration damping element is provided in parallel with the torsional damper 4. This has already been proposed by the present applicant as Japanese Patent Application No. 3-115233.

In FIG. 3, 3 is a converter housing, 6 is a drive plate fixed to the crank end 1 with bolts 5, and 6a is a starter ring gear.

As shown in FIG. 4 (a view of the arrow A in FIG. 3), the drive plate 6 is formed with three windows 6b at equal intervals in the circumferential direction, and each window 6b has a central portion in the circumferential direction. At, a protruding portion 6c extending in the radial direction is provided. This protrusion 6c
The coiled torsion springs 10 and 10 are housed in a contracted state between and and the circumferential side walls 6d and 6d of the windows 6b.

Before and after the drive plate 6 (right and left in FIG. 3)
The driven plates 7 and 8 arranged in the drive plate 6 are integrally coupled by the rivet 12 and
It is attached so as to be rotatable relative to.

On the rear driven plate 7 fixed to the torque converter 2 by the bolt 9, the above-mentioned window 6b is provided.
Corresponding to the window in the circumferential direction (only one is shown in FIG. 4) 1
1 are formed at equal intervals, and two torsion springs 10, 10 adjacent to each other on both sides of the projecting portion 6c protrude from the window 11 toward the front in the drawing of FIG.

The window 11 is also provided on the front driven plate 8 at the same position in the circumferential direction. That is, a part of the torsion springs 10, 10 protrudes from the pair of windows 11, 11 facing each other at the same circumferential position with the drive plate 6 interposed therebetween, as shown in FIG. Therefore, for example, when the drive plate 6 rotates clockwise in FIG. 4, the torsion spring 10
The spring end of which is one circumferential side wall 11a of the window 11.
And the counterclockwise rotation in turn engages the other circumferential side wall 11b of the window 11.

Due to the engagement in the rotational direction, the engine torque transmitted to the drive plate 6 is transmitted from the torsion spring 10 to the torque converter 2 via the driven plates 7 and 8. In this way, the torsion spring 10 is attached to the side of the drive plate 6 and the window 1
When the torsional damper 4 is configured by arranging 1 on the side of the driven plates 7 and 8, the power is transferred through the torsion spring 10, so that the impact of the deflection of the torsion spring 10 is absorbed, Power transmission is performed smoothly.

By the way, the torsion spring 10 is
When the impact occurs, the crank end 1 contracts when it receives an impact, and it contracts, and the elastic energy stored in the contracted torsion spring 10 is used to extend the original state.
Rotational vibration remains between the torque converter 2 and the torque converter 2.

In order to damp this rotational vibration, a viscous coupling 13 such as a viscous coupling (trade name) is provided in parallel with the torsional damper 4. The coupling may be a friction coupling.

A shaft 2a, which is concentric with the crankshaft, is formed so as to project from the torque converter 2 to a position where it is fitted into a stepped hole provided in the crank end 1. An inner hub 16 is provided between the concentric shaft 2a and the crank end 1. Are placed. The outer periphery of the inner hub 16 is rotatably supported by the small-diameter hole 1a by a bearing 15, and the inner periphery of the inner hub 16 is coupled to the concentric shaft 2a by a spline 16a.

As shown enlarged in FIG. 5, the space provided between the outer periphery of the inner hub 16 and the large diameter hole 1b is
A plurality of inner plates 17 and outer plates 18 are alternately arranged in the axial direction (left-right direction in the drawing). Among these, the inner plate 17 is connected to the inner hub 16 at the inner periphery thereof, and the outer plate 18 is connected to the large diameter hole 1b at the outer periphery thereof by the splines 16b and 1c, respectively. Further, the distance between the thin plate-like plates is kept constant by a spacer ring 19, a highly viscous substance (for example, silicon oil) is filled in a closed space accommodating the plates 17 and 18, and is sealed by a seal ring 20. There is.

If rotational vibration remains due to the torsional damper 4, relative rotation occurs between the outer plate 18 that rotates integrally with the crank end 1 and the inner plate 17 that rotates integrally with the torque converter 2. However, due to this relative rotation, both plates 1
7, 18 shear the silicon oil. This shearing force acts as a resistance to relative rotation. As a result, the rotational vibration due to damping is damped.

FIG. 6 is a system diagram of a fuel control system for an engine having an automatic transmission 20. The fuel is synchronized with the engine rotation from one injector 30 provided in the intake port regardless of whether the amount of fuel is large or small. Supplied. In the illustrated four-cylinder engine, one injector is provided for each cylinder, torque is generated for each cylinder, and the combined torque acts on one crankshaft.

The throttle valve 23 provided in the intake pipe 22 is not interlocked with the accelerator pedal 26, and is driven by the throttle actuator 24 here.

A signal from an accelerator sensor 27 is input to a control unit 31 composed of a microcomputer together with signals from an air flow meter 28 for detecting an intake air amount and a crank angle sensor (rotation speed sensor) 29, and the control unit 31 is controlled. Then, the throttle valve 23 corresponding to the depression amount of the accelerator pedal 26
Is determined, and the drive pulse width (fuel injection pulse width) to the injector 30 is determined according to the intake air amount and the engine speed. As the accelerator pedal 26 is stepped on, the throttle valve 23 is widened to promote the inflow of a large amount of air into the cylinder, and the amount of fuel supplied to each cylinder is increased corresponding to the amount of air adjusted by the throttle valve 23. is there.

On the other hand, at the time of starting, the throttle valve 23 is opened according to the command value from the control unit regardless of the accelerator pedal. In order to allow the required amount of air to flow in at the time of starting, the conventional device has a mechanical stopper that keeps a minute opening even when the throttle is fully closed, or bypasses the throttle valve to allow air to flow. According to the command value from 31, the throttle valve opening is maintained so that the required amount of air flows in at the time of starting.

The throttle valve is mechanically connected to the accelerator pedal, and the opening of a sub-throttle valve (this valve is driven independently of the accelerator pedal) provided in a passage bypassing the throttle valve is controlled. It can also be controlled by a signal from the unit.

By the way, a rotary vibration system constructed by connecting a torque converter to the crank end 1 through a torsional damper 4 twists between two masses having an inertia moment as shown in FIG. Stiffness k
It is grasped as a vibration model in which the torsional damper 4 and the viscous coupling 13 having the damping rate c are arranged in parallel, and this vibration model has an inherent resonance point corresponding to two constants (k and c).

On the other hand, in a four-cycle four-cylinder engine, a secondary harmonic component of rotation remains in the combined torque generated in the crankshaft by the explosion pressure of each cylinder, and this acts as an exciting force. The frequency of this exciting force (exciting frequency) changes according to the engine speed, and increases as the engine speed increases.

For this reason, when the vibration frequency coincides with or is close to the frequency at the resonance point, a resonance phenomenon occurs in the above vibration model. As shown in FIG. 8, when the vibration transmissibility is plotted on the vertical axis and the engine rotational speed is plotted on the horizontal axis, a peak occurs near a certain rotational speed N ₀ , and this appears as a large torque fluctuation.

To avoid this, the flow chart shown in FIG. 9 is constructed in this example, which is executed by the microcomputer.

In FIG. 9, a predetermined rotation range is defined around the rotation speed N ₀ corresponding to the frequency of the resonance point (lower limit value is α and upper limit value is β), and the actual engine rotation speed is in the meantime. If so, the fuel in half the cylinders is cut (steps 1 and 2).

For fuel cut, ignition is # 1- # 3- # 4-
If the process is performed in the order of # 2, the fuel is cut off one by one in the ignition order such as the first cylinder and the fourth cylinder or the third cylinder and the second cylinder. This is because the vibration frequency changes according to the number of explosions, so the vibration frequency is reduced by reducing the number of explosions. By this fuel cut, the vibration frequency is switched to 1/2 if the rotation speed is the same. However, if the fuel is cut off from the two cylinders having the consecutive ignition orders such as the first and third cylinders or the fourth and second cylinders, the effect of modulating the vibration frequency becomes poor.

However, since the engine rotation range in which the resonance phenomenon occurs is in a region lower than the idle rotation speed (originally, the region where the engine rotation is unstable), when the number of combustion cylinders becomes half, the engine torque is proportionally increased. The size is also halved, making the engine rotation more and more unstable, and we cannot expect a rise in rotation.

Therefore, the intake air amount is doubled so that the engine torque does not decrease even if the number of combustion cylinders is reduced to half (step 3). The throttle actuator 24 is driven to open the throttle valve 23 so that twice the amount of air flows.

Now, the operation of this example will be described with reference to FIG.

The vibration frequency increases in proportion to the engine speed, as shown by the alternate long and short dash line. At the time of start-up, the engine speed rises along this line and settles at the idle speed N ₁ (for example, 700 to 800 rpm).

In this case, in the conventional example, the engine rotation crosses the engine rotation speed (N ₀ ) corresponding to the resonance point at the point F, and the torque fluctuation due to resonance occurs near this rotation speed N _0. growing.

On the other hand, in the embodiment, when the engine speed reaches the lower limit value α of the predetermined rotation range, half of the cylinders are subjected to the fuel cut, so that the vibration frequency becomes 1/2 of that of all cylinder combustion. become. That is, when the engine speed reaches α, the characteristic shifts to the characteristic shown by the broken line in FIG. 10 (excitation frequency characteristic at the time of half-cylinder combustion).

In this case, although the torque is not generated in the cylinder from which the fuel has been cut, the remaining combustion cylinders whose intake amount is doubled are supplied with double the fuel accordingly, whereby the respective combustion cylinders are supplied. Generates twice as much torque, the total engine torque remains unchanged,
Therefore, the rotation increases from the point B along the broken line characteristic to the point D.

Between B and D, the characteristic of the vibration frequency (that is, the characteristic at the time of half-cylinder combustion) runs at a position lower than the one-dot chain line, so it does not coincide with the frequency of the resonance point, and neither approaches. The resonance phenomenon does not occur.

Then, when the fuel cut is stopped at the engine speed that matches the predetermined upper limit value β and combustion is performed in all cylinders, the vibration frequency returns from point D to the one-dot chain line characteristic. The excitation frequency doubles as the number of explosions returns to the original value. Moreover, since the throttle valve 23 is returned to the original position so that the air amount becomes 1/2 at β, the engine torque does not change.

In this way, the vibration frequency (the vibration frequency at point E) when returning to the characteristics at the time of combustion in all cylinders exceeds the frequency at the resonance point, so no resonance occurs.

The characteristic is D when the fuel cut is stopped.
When passing from E to E, the frequency of the resonance point is crossed, but since the vibration frequency is switched from D to E in an instant, there is no problem. The engine speed can be changed only continuously, but the vibration frequency can be switched discontinuously.

In the embodiment, the four cylinder engine is explained, but
It is not limited to this. In a 6-cylinder engine, the third harmonic component of rotation acts as an exciting force,
The present invention can be applied in the same manner as in the case of four cylinders. The vibration frequency in the case of 6 cylinders is shown in FIG. 11 in correspondence with the case of 4 cylinders. The characteristic of FIG. 10 is created from the data of four cylinders shown in FIG.

Further, it is best to perform the fuel cut on half of the cylinders, but it may be performed on only some of the cylinders if the vibration frequency can be changed from that at the time of combustion in all cylinders.

[0055]

According to the first aspect of the present invention, the actual engine speed is detected, and it is determined whether or not the sensor detection value is within a predetermined range of speed including the engine speed corresponding to the resonance point. Since the number of cylinders in which torque is generated is limited when the sensor detection value is in the rotation range, the resonance phenomenon does not occur.

A second aspect of the present invention detects the actual engine speed and determines whether or not this sensor detection value is within a predetermined range of rotation speed including the engine speed corresponding to the resonance point.
When the sensor detection value is in this rotation range, the number of cylinders in which torque is generated is limited and the torque generated per cylinder is increased. Therefore, in addition to the effect of the first aspect of the present invention, the resonance point is supported. Even when the engine rotation range is set to a region smaller than the idle rotation speed, the engine rotation is not unstable.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to claims of the first invention.

FIG. 2 is a diagram corresponding to claims of the second invention.

FIG. 3 is a vertical sectional view of a connecting portion between a crankshaft and a torque converter according to an embodiment.

FIG. 4 is a view on arrow A in FIG.

5 is an enlarged view of a main part of FIG.

FIG. 6 is a control system diagram of an embodiment.

FIG. 7 is a vibration model including an engine and a torque converter.

FIG. 8 is a characteristic diagram of vibration transmissibility with respect to engine speed.

FIG. 9 is a flowchart showing the control contents of the embodiment.

FIG. 10 is a characteristic diagram of vibration frequency with respect to engine speed.

FIG. 11 is a table showing vibration frequencies for four cylinders and six cylinders.

FIG. 12 is a waveform diagram for explaining the operation of the conventional example.

[Explanation of symbols]

 1 Crank End 2 Torque Converter 4 Torsional Damper 6 Drive Plate 13 Viscous Coupling 21 Engine 23 Throttle Valve 28 Air Flow Meter 29 Crank Angle Sensor (Engine Speed Sensor) 30 Injector 31 Control Unit 41 Engine 42 Crank Shaft 43 Torsional Damper 44 Torque converter 46 Engine speed sensor 47 Rotation range determining means 48 Torque generating cylinder limiting means 49 Generated torque increasing means

Claims (2)

[Claims] 1. A sensor for detecting an actual engine speed in an engine for generating torque for each cylinder while a torque converter is connected to an end of a crankshaft via a torsional damper, and a sensor detection value of the sensor. Means for determining whether or not the engine is in a rotation range of a predetermined width including the engine speed corresponding to the resonance point of the rotational vibration generated by the torsional damper, and torque is generated when the sensor detection value is in this rotation range. A fuel control device for an engine, comprising: means for limiting the number of cylinders. 2. A sensor for detecting an actual engine speed in an engine for generating torque for each cylinder while a torque converter is connected to an end portion of a crankshaft via a torsional damper, and a sensor detection value of the sensor. Means for determining whether or not the engine is in a rotation range of a predetermined width including the engine speed corresponding to the resonance point of the rotational vibration generated by the torsional damper, and torque is generated when the sensor detection value is in this rotation range. A fuel control device for an engine, comprising: a means for limiting the number of cylinders; and a means for increasing the generated torque per cylinder when a sensor detection value is present in the rotation range.