JPH05113130A - Torque fluctuation reduction device for internal combustion engine - Google Patents

Abstract

PURPOSE:To accurately reduce torque fluctuation irrespective of operation condition of an engine. CONSTITUTION:In a torque fluctuation reduction device for an internal combustion engine provided with a cam 11 which rotates synchronously with an engine crank shaft and a spring 21 which extends and contracts interlockingly with the cam 11 within a specified rotary angle, a phase variable mechanism 26 is provided for varying a lifting position of the cam 11 according to an operation condition of the engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque fluctuation reducing device for an internal combustion engine.

[0002]

2. Description of the Related Art In order to reduce the torque fluctuation of an internal combustion engine, an elliptical cam is provided on the crankshaft of the engine, and a spring is arranged which responds to the cam and contracts and then restores during the explosion stroke of the engine. is there.

This is because the spring contracts through the cam to absorb the torque due to the contraction of the spring, and the torque absorbed by the spring is then added via the cam to smooth the engine rotation. It has become (Actual development Sho 59-32137
No.

[0004]

However, in such a conventional example, since the lift characteristic of the cam is constant, torque fluctuation cannot be reduced so appropriately.

That is, since the combustion peak differs depending on the engine speed and the like, if the lift characteristics of the cam are adjusted at idle, the timing of torque absorption will not match when the engine speed is high, and the reduction effect will be that much. It becomes smaller.

Further, the set load of the spring is constant, and only a constant torque can be absorbed.

For this reason, for example, when the torque is large and the load is medium to high, the spring force is insufficient and the torque fluctuation cannot be reduced so much.

The present invention aims to solve such problems.

[0009]

SUMMARY OF THE INVENTION The present invention provides a torque fluctuation reducing apparatus for an internal combustion engine in which a cam that rotates synchronously with an engine crankshaft is provided and a spring that responds to the cam and expands and contracts within a predetermined rotation angle is arranged. In the above, there is provided a phase changing mechanism for changing the lift position of the cam according to the operating condition of the engine.

Further, a spring load varying mechanism for varying the load of the spring according to the operating conditions of the engine is provided.

[0011]

Therefore, by changing the lift position of the cam depending on the operating condition of the engine, the torque can be accurately absorbed and added even if the combustion state is different.

Further, when the engine is in a medium to high load, the spring is strengthened so that the torque can be absorbed and added according to the engine torque.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 are applied to a 4-cylinder 4-cycle engine, 10 is a cylinder block of the engine,
Reference numeral 11 denotes an elliptical cam arranged in a cover 12 mounted inside the cylinder block 10.

The cam 11 is rotatably supported by bearings 13 and 14 provided on the cylinder block 10 and the cover 12 via a shaft 15.

Inside the cover 12, a cam 11 is provided between the two.
Two rocker arms 16 are symmetrically arranged so as to be freely swingable via pins 18 each having one end supported by a frame portion 17.

A roller 19 is provided at the center of the rocker arm 16 for contacting the cam 11, and a predetermined coil spring 21 is provided between the free end of the rocker arm 16 and the frame end 20 for each retainer portion 22, 23. Both ends are positioned and interposed, and the roller 19 is pressed against the cam 11.

On the other hand, the shaft 15 of the cam 11 is connected to a timing pulley 25, to which the rotation of a crank shaft (not shown) is transmitted by a timing belt 24, via a phase variable mechanism 26.

In the phase variable mechanism 26, as shown in FIG. 3, a plunger gear (helical gear) 29 is provided on a helical gear 28 formed on a housing 27 integral with the timing pulley 25.
However, the inner helical gear 30 fixed to the cam shaft 15 meshes with the plunger gear 29, and the timing pulley 25
Rotation of the plunger gear 29 while transmitting the rotation of the
The cam shaft 15 rotates relative to the timing pulley 25 by a predetermined angle by the driving in the axial direction.

When the oil drain hole of the control valve 31 provided in the housing 27 is open, the plunger gear 29 is at the position shown in FIG. 3, and when the oil drain hole of the control valve 31 is closed from this state, an oil not shown is shown. The pressure of the lubricating oil supplied from the gallery to the bearing 13 of the cam shaft 15 is changed by the oil passage 32 in the cam shaft 15.
From the end to the end of the helical gear 30 acting on the hydraulic chamber 33 as shown in FIG. 4, and the plunger gear 29 advances the cam shaft 15 to a predetermined stopper position while rotating the cam shaft 15 relatively (in the direction of advancing the lift position of the cam 11). ..

The control valve 31 is a solenoid 3
4, the oil drain hole is closed, and the solenoid 34 is turned on by the control device 35, to which the engine operating condition signal is input, in the low speed range where the engine speed is equal to or lower than a predetermined value, and the predetermined value. It is supposed to be turned off when it exceeds.

Although the cam 11 lifts the rocker arm 16 every half rotation, the lift position, that is, the phase of the cam 11 is set so as to be advanced or retarded within a predetermined range of the explosion stroke of the engine.

Next, the operation will be described.

The timing belt 2 rotates the crankshaft.
4, the cam 11 that is transmitted to the cam shaft 15 via the timing pulley 25 and the phase changing mechanism 26 and rotates synchronously contracts the coil spring 21 via the rocker arm 16 during a predetermined period of the explosion stroke of the engine to absorb the torque. During the subsequent predetermined period (during the compression stroke of the different cylinder), the coil spring 21 pushes the cam 11 via the rocker arm 16 to return the absorption torque.

As described above, when the engine torque increases, the coil spring 21 absorbs the torque, and when the engine torque decreases, the absorbing torque of the coil spring 21 is added to reduce the engine torque fluctuation. In this case, the combustion peak varies depending on the engine operating conditions.

That is, during idle operation of the engine (four-cycle four-cylinder engine), the combustion is short-term, and the torque fluctuation caused by the combination of the explosion pressure due to the combustion, the gas pressure due to the compression, and the inertial force due to the reciprocating parts is , As shown in FIG.

When the engine is idling, the solenoid 34 is turned on (see FIG. 5), the oil drain hole of the phase changing mechanism 26 is closed, and the pressure of the lubricating oil acting on the hydraulic chamber 33 causes the plunger 29 to move. Holds in the forward position.

Therefore, the lift position of the cam 11 is in a predetermined advance condition, that is, a position suitable for the combustion condition during idling.

Therefore, as the cam 11 rotates, as shown in FIG.
It is possible to obtain the absorption torque and the additional torque of the coil spring 21 as described above, and it is possible to sufficiently reduce the torque fluctuation at the time of idling as shown in FIG.

It should be noted that there is an optimum value for the advance angle of the phase of the cam 11 as shown in FIG. 9, and this value is larger as the engine speed is smaller.

On the other hand, when the engine speed increases, the solenoid 34 is turned off, the oil drain hole of the phase changing mechanism 26 is opened, the pressure in the hydraulic chamber 33 is released, and the plunger 29 is retracted.

For this reason, the lift position of the cam 11 is retarded, and as a result, the lift is performed at a timing that matches the rotation range in which the combustion period becomes longer.

Therefore, even when the engine speed is high, the coil spring 21 can efficiently absorb and add the torque, and the torque fluctuation can be appropriately reduced.

10 and 11 show the variable load of the coil spring 21 of the above embodiment.

The coil spring 21 is composed of a free end of a rocker arm 16 provided with a cam 11 between them and a rod 41 of a hydraulic actuator 40 attached to a frame end 20 inside the cover 12 as a spring load varying mechanism. It is interposed between.

Both ends of the coil spring 21 are connected to the rocker arm 1
6, free end retainer portion 22, hydraulic actuator 40
The rod 41 is hooked on the retainer portion 42 at the tip of the rod 41 and positioned.

The hydraulic actuator 40 is composed of a hydraulic cylinder in which a piston 43 having a rod 41 mounted therein is slidably accommodated, and a hydraulic passage 46 is connected to a hydraulic chamber 44 via a distribution passage 45. One of the distribution passages 45 is not shown.

The hydraulic passage 46 is used for the bearing 1 of the camshaft 15.
A return passage 47, which is connected to an oil gallery not shown in the drawings at 3 and 14, and branches off upstream of the distribution passage 45.
A solenoid valve 48 is installed in. In addition, a predetermined hydraulic accumulator 50 is connected to the hydraulic passage 46 upstream of this branch portion via an electromagnetic valve 49.

Then, the solenoid valve 48 is closed by the control device in the medium to high load range where the engine speed is below a predetermined value as shown in FIG. 12, and the solenoid valve 49 is opened when the solenoid valve 48 is closed. It has become so.

The cam advance angle region in FIG. 12 is the phase variable mechanism 2
6 is the ON area of the solenoid 34.

The other components have the same reference numerals as those in FIGS.

That is, in the low load range including the idling time, the solenoid valve 48 of the return passage 47 of the hydraulic passage 46 is kept open, the solenoid valve 49 of the hydraulic accumulator 50 is kept closed, and the hydraulic actuator 40 is shown. Is held in the contracted position.

Therefore, the coil spring 21 is in the initial set state, that is, in the set load that matches the torque in the low load region,
In this case, the absorption torque and the additional torque of the coil spring 21 as indicated by A in FIG. 13 are obtained.

On the other hand, in the medium to high load range, the solenoid valve 4 in the return passage 47 of the hydraulic passage 46 is closed and the solenoid valve 49 of the hydraulic accumulator 50 is opened.

Then, the hydraulic pressure acts to extend the rod 41 of the hydraulic actuator 40, and the spring length of the coil spring 21 is shortened by the stroke of the rod 41.
The load of 1 is increased and the spring force is strengthened.

Therefore, the engine torque is high
In the high load range, the absorption torque and the additional torque of the coil spring 21 become large as shown in FIG. 13B, and as a result, the torque fluctuation in the medium to high load range can be sufficiently reduced in the low load range.

Since the hydraulic accumulator 50 is connected to the hydraulic passage 46, it is possible to prevent a delay in the rise of hydraulic pressure when the engine is started, and to quickly drive the hydraulic actuator 40.

[0048]

INDUSTRIAL APPLICABILITY As described above, the present invention provides a torque fluctuation reducing apparatus for an internal combustion engine in which a cam that rotates in synchronization with an engine crankshaft is provided and a spring that responds to the cam and expands and contracts within a predetermined rotation angle is arranged. In the above, since a phase variable mechanism that changes the lift position of the cam according to the operating conditions of the engine is provided, torque can be efficiently absorbed and added according to the combustion state of the engine, and torque fluctuation is accurately reduced. Further, since the spring load varying mechanism that varies the load of the spring according to the operating condition of the engine is provided, the torque fluctuation can be sufficiently reduced even in the load region where the torque is large.

[Brief description of drawings]

FIG. 1 is a configuration cross-sectional view.

FIG. 2 is a front view.

FIG. 3 is a cross-sectional view of a phase variable mechanism.

FIG. 4 is a cross-sectional view showing an operating state of a phase variable mechanism.

FIG. 5 is a characteristic diagram showing an operating range of a phase variable mechanism.

FIG. 6 is a characteristic diagram showing torque fluctuation during idling.

FIG. 7 is a characteristic diagram showing a state of absorbing and adding torque of a coil spring.

FIG. 8 is a characteristic diagram showing a torque fluctuation reducing effect.

FIG. 9 is a characteristic diagram showing the effect of reducing torque fluctuations with respect to cam phase and rotation speed.

FIG. 10 is a sectional view showing the configuration of another embodiment.

FIG. 11 is a front view thereof.

FIG. 12 is a characteristic diagram showing an operating range of a hydraulic actuator.

FIG. 13 is a characteristic diagram showing how a coil spring torque is absorbed and added when the hydraulic actuator is turned on and off.

[Explanation of symbols]

 11 cam 12 cover 15 cam shaft 16 rocker arm 19 roller 21 coil spring 25 timing pulley 26 phase variable mechanism 29 helical gear 31 control valve 32 oil passage 34 solenoid 35 control device 40 hydraulic actuator 41 rod 46 hydraulic passage 48 electromagnetic valve

Claims (2)

[Claims] 1. A torque fluctuation reducing apparatus for an internal combustion engine, comprising: a cam that rotates synchronously with an engine crankshaft; and a spring that expands and contracts within a predetermined rotation angle in response to the cam. A torque fluctuation reducing device for an internal combustion engine, comprising a phase changing mechanism for changing the lift position of the cam. 2. The torque fluctuation reducing apparatus for an internal combustion engine according to claim 1, further comprising a spring load varying mechanism that varies a spring load according to operating conditions of the engine.