JPH03265737A - Torque fluctuation relaxation device for internal combustion engine - Google Patents

Abstract

PURPOSE:To enhance the responsiveness of an engine in a range of high revolution as well as to concurrently prevent friction and oscillation from being increased by providing a torque fluctuation absorbing mechanism for a cam which is rotated while being synchronized with a crank shaft, and thereby changing energizing force to the cam in response to engine operating conditions. CONSTITUTION:In an operating range where engine revolution is less than specified one, a controller closes each closing valve 25, each piston 21 of hydraulic actuators 20 is subjected to hydraulic pressure so that each piston is pushed so as to be moved forward, each acting rod 23 is then moved while stoppers 32 at slant sections B come in contact with each other so that the fulcrum sections (b) of both levers 18 are kept at a position where both of the fulcrums come close together respectively. Under this condition, each roller 17 is lifted up around each fulcrum section (b) with a cam 16 rotates, and each fulcrum section (a) is subjected to the elastic force of a tension spring 19 so that torque fluctuation produced by an engine can thereby be cancelled by torque fluctuation in anti-phase. In an operating range where engine revolution exceeds specified one, the controller opens the closing valve 25, so that the fulcrum sections (b) of both of the levers 18 are kept at positions where both of the fulcrum sections are mutually parted.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a torque fluctuation mitigation device for an internal combustion engine, and more particularly to a device capable of controlling the torque fluctuation absorption function according to engine operating conditions.

<Prior art> In order to improve the fuel consumption rate of an internal combustion engine, it is preferable to use the engine in a low speed range as much as possible, but in a low speed range such as during idling, the engine speed decreases as the engine speed decreases. The number fluctuation becomes noticeable, causing problems such as transmission noise and engine vibration.

Therefore, it is conceivable to use a flywheel with a large inertial force, but this is not practical due to restrictions such as engine size, shape, weight, etc.

Therefore, conventionally, a torque fluctuation mitigation device has been known that solves the above problem by absorbing engine torque fluctuation without increasing the inertia force of the flywheel. Publication No. 155143, Utility Model Publication No. 1983-1
(See Japanese Utility Model Publication No. 72018 and Japanese Utility Model Application Publication No. 59-32137, etc.).

Here, an example of such a conventional torque fluctuation mitigation device will be described in the sixth section.
This will be explained based on FIGS.

6 and 7, a flywheel 2 is attached to the end of a crankshaft 1 of an internal combustion engine, and a large spur gear 3 is attached to the outer periphery of the crankshaft I near the flywheel 2. A small spur gear 4 meshing with the large spur gear 3 is rotatably supported by a cylinder block 5.

The small spur gear 4 is configured as an eccentric cam by having a protruding pin 6. A bearing 7 is fitted to this pin 6,
One end of a tension spring 8 is fixedly attached to the bearing 7. The other end of this tension spring 8 is connected to a stationary side 9 of the engine.

In this configuration, as the crankshaft 1 rotates, torque fluctuations occur in the engine due to the explosion pressure in the combustion chamber, as shown in FIG. 8(a).

On the other hand, the small spur gear 4 meshes with the large spur gear 3 and rotates at twice the speed. Torque fluctuations occur in the small spur gear 4 every rotation due to the tension spring 8, as shown in FIG. In this case, the torque fluctuations applied to the small spur gear 4 are adjusted to be in opposite phase to the torque fluctuations occurring in the crankshaft 1 described above.

Therefore, the torque fluctuations generated in the engine are completely canceled by the torque fluctuations generated by the tension spring 8, and the torque fluctuations are completely canceled or partially canceled so as to match the horizontal axis in FIG. Therefore, only a slight torque fluctuation remains as shown by the broken line in FIG.

<Problems to be Solved by the Invention> However, in the conventional torque fluctuation mitigation device as described above, the torque fluctuation absorbing action always occurs regardless of the operating conditions of the engine, and the action of the tension spring 8 and the eccentric cam is Since the structure is such that torque fluctuations due to the biasing force applied by the engine are constantly applied to the crankshaft 1, the responsiveness of the engine deteriorates in the high rotation range of the engine, and the friction increases.
There was a problem that vibration increased.

Therefore, in view of the above-mentioned conventional problems, the present invention has a configuration that controls the torque fluctuation absorption effect according to the operating conditions of the engine, thereby making it possible to set the rotation speed at a low value during idling, thereby reducing the fuel consumption rate. The present invention aims to eliminate the inconvenience caused by torque fluctuations that are always applied to the crankshaft in a phase opposite to the torque fluctuations that occur in the crankshaft, while effectively achieving the original purpose of the device to reduce the amount of torque that occurs in the crankshaft.

<Means for solving the problem> For this reason, the torque fluctuation mitigation device for an internal combustion engine of the present invention has the following features:
The configuration includes a cam that rotates in synchronization with the crankshaft and a biasing force applying means that applies a biasing force to the cam, the cam generating torque fluctuations having a phase opposite to the torque fluctuations occurring in the crankshaft. The engine is configured to include a torque fluctuation absorbing mechanism and a control means for controlling the operation of the urging force applying means to change the urging force according to engine operating conditions.

<Operation> In this configuration, as the crankshaft rotates,
Explosion pressure in the combustion chamber and gas pressure associated with compression act on each cylinder of the crankshaft, causing torque fluctuations.

On the other hand, torque fluctuations in the valve train also act, and the combined torque acts on the crankshaft.

For example, as an engine operating condition, in the low rotation range of the engine, torque fluctuations with the opposite phase to the above torque fluctuations are set as
By generating torque in the cam, torque fluctuations occurring in the engine can be canceled out by torque fluctuations in the opposite phase.

Therefore, the rotational speed during idling can be set low, and the fuel consumption rate can be reduced.

Furthermore, since the flywheel can be downsized or omitted, various rank shaft vibrations caused by the flywheel can be prevented.

Next, for example, in the high speed range of the engine, by controlling the operation of the biasing force applying means to eliminate the torque fluctuation absorption function, the responsiveness of the engine in the high speed range is improved and the friction is increased. , it is possible to prevent an increase in vibration.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, the end of the crankshaft 10 passes through the end wall of the cylinder block 11 and projects to the outside, and this projecting end is sealed with an opening 13 of a cover 12 connected to the end wall of the cylinder block 11. A main drive shaft 15 passing through the member 14 is connected by spline fitting.

A substantially elliptical cam 16 is integrally formed on the outer periphery of the protruding end of the crankshaft IO.

Here, the structure includes a biasing force applying means for applying a biasing force to the cam 16 rotating in synchronization with the crankshaft lO, and the cam 16 has a phase opposite to the torque fluctuation produced in the crank jab 10. A torque fluctuation absorbing mechanism configured to generate torque fluctuations is provided.

Such a torque fluctuation absorbing mechanism is configured as follows.

That is, a pair of rollers 17 each having a rotation center axis parallel to the center axis is disposed at two opposing positions along a cross section perpendicular to the center axis of the cam 16 on the outer periphery of the cam 16.
The pair of rollers 17 are rotatably supported by a pair of levers 18, respectively, and are brought into contact with the outer peripheral surface of the cam 16. The levers 18 are disposed at two opposing positions along a cross section perpendicular to the central axis of the cam 16 on the outer peripheral side thereof. Each lever 18 includes a pair of lever members 18a,
18a are arranged in parallel and facing each other at a predetermined interval. Furthermore, each lever member 18a includes a straight portion A and an inclined portion B that extends obliquely from one end of the straight portion A and then extends substantially linearly again.
It consists of Each lever 18 has the linear portion A
are parallel to each other, and the end of the inclined part B is the other lever 18.
It is arranged so that it is in a position where it can come into contact with.

Fulcrum portions a and b are formed at the tip of the straight portion A and the tip of the inclined portion B of the lever 18, respectively. here,
The fulcrum portions a are connected to each other via a tension spring 19, and the tension spring 19 exerts an elastic force that draws the tips of the levers 18 to the other lever 18.

Further, a control means is provided for controlling the operation of the urging force applying means in order to change the urging force according to engine operating conditions.

This control means is constructed as follows.

That is, a pair of hydraulic actuators 20 are provided that operate in directions that move the base end portions of the inclined portions B of each lever 18 toward and away from each other. This hydraulic actuator 20 has a piston 21 slidably provided in a main body 20A, and a hydraulic chamber 22 is formed in a space on the bottom side of the piston 21.

An actuating rod 23 is provided on the tip side of the piston 21 and projects outward from the main body 2OA. Such a piston 21 is
It is slid back and forth by controlling the inflow and outflow of hydraulic pressure into the hydraulic chamber 22 by a hydraulic control device.

The hydraulic control device is configured as follows.

That is, a hydraulic pressure introduction pipe 2 connected to an engine hydraulic pressure source (not shown)
4 is communicatively connected to the hydraulic chamber 22 of the hydraulic actuator 20. A hydraulic pressure outlet pipe 26 in which an on-off valve 25 is interposed is connected to the connecting end of the hydraulic pressure introduction pipe 24 with the hydraulic pressure chamber 22 . Further, a hydraulic accumulator 29 is connected to the upstream side of the connection part of the hydraulic pressure introduction pipe 24 with the hydraulic chamber 22 via a pipe 28 in which an on-off valve 27 is interposed.

The distal end portion of the operating rod 23 of the hydraulic actuator 20 is rotatably connected to the fulcrum portion.

The tip of the inclined portion B of each lever 18 is connected to the other end of a tension spring 31 whose one end is connected to the fixing portion 30 . This tension spring 31 applies a weak elastic biasing force in a direction to separate the tips of the inclined portion B of the lever 18 from each other.

Incidentally, on the inner surface of the inclined portion B corresponding to the formation position of the fulcrum portion, there is a stopper portion 32 consisting of a convex portion formed in an arcuate surface.
is formed, and the stopper parts 32 are configured to abut each other and to be slidable.

Here, an engine rotation speed sensor (not shown) is provided as a means for detecting engine operating conditions, and a controller (not shown) is provided that executes opening/closing control of the on-off valve 25 based on a detection signal from the sensor. .

The hydraulic accumulator 29 has a function of constantly accumulating hydraulic pressure that flows into the hydraulic chamber 22 in order to compensate for a delay in the rise of hydraulic pressure at the time of starting.

Next, the operation of this configuration will be explained.

As the crankshaft 10 rotates, in a 4-stroke, 4-cylinder internal combustion engine, explosion pressure in the combustion chamber and gas pressure associated with compression act on each cylinder of the crankshaft 10, as shown in FIG. 2(b). The bottom torque acts. On the other hand, torque fluctuations in the valve train system as shown in FIG. 3(C) also act, and torque fluctuations shown by solid lines in FIG. 1(a) act on the crankshaft 10 as these bottom torques. still,
FIG. 2 above shows torque fluctuations in an operating region where the engine speed is less than a predetermined value, such as during idling.

Then, in an operating region where the engine speed is less than a predetermined value, for example,
The operation of generating torque fluctuations in phase opposite to the torque fluctuations shown in FIG. 2(a) during idling using the above-described embodiment will be described.

That is, hydraulic pressure from the engine hydraulic pressure source flows into the hydraulic chamber 22 of the hydraulic actuator 20 via the introduction pipe 24 . In this case, the controller outputs a signal to close the on-off valve 25 based on an input signal from the rotation speed sensor that detects that the engine rotation speed is less than a predetermined value.

When the piston 21 of the hydraulic actuator 20 receives the hydraulic pressure introduced into the hydraulic chamber 22, it is pushed forward and the actuating rod 23 moves forward. In this case, the actuating rod 23
moves against the elastic force of the tension spring 19 which attempts to open the tips of the inclined portion B of the lever 18.

As a result, the stopper portions 32 of the inclined portions B come into contact with each other, and hold the fulcrum portions of both levers 18 in a position where they are close to each other so as not to be movable.

In this state, each roller 17 is rotated by the rotation of the cam 16.
lifts around the fulcrum as shown in Figure 3.

The elastic force of the tension spring 19 acts on the fulcrum part a, and a negative torque acts on the crankshaft 10 when the cam 16 goes up the mountain, and a positive torque acts on the crankshaft 10 when it goes down. The profile of the cam 16 can create a suitable shape for the opposing anti-phase torque waveform, and the torque fluctuations occurring in the engine can be canceled out by the anti-phase torque fluctuations.

Incidentally, in this case, by changing the number of ridges on the cam 16, it can be made compatible with engines having six cylinders, eight cylinders, etc.

As described above, a biasing force is applied to the cam 16 that rotates in synchronization with the crankshaft 10, and torque fluctuations in the opposite phase to the torque fluctuations generated by the engine are generated in the low rotation range including idling. As a result, the engine speed can be set low during idling, etc., and the fuel consumption rate can be reduced.

Further, since the flywheel can be downsized or omitted, various rank shaft vibrations caused by the flywheel can be prevented.

Next, a description will be given of the effect of stopping the above-mentioned torque fluctuation absorbing mechanism in the operating range M where the engine speed is equal to or higher than a predetermined value.

That is, the controller outputs a signal to open the on-off valve 25 based on an input signal from a rotation speed sensor that detects that the engine rotation speed is equal to or higher than a predetermined value.

By opening the hydraulic pressure outlet pipe 26, the hydraulic actuator 2
The pressure in the hydraulic chamber 22 at 0 decreases. Therefore, piston 2
This causes a decrease in the hydraulic pressure acting on 1.

As a result, the actuating rod 23 moves the tension spring 1
9 and the elastic force of the tension spring 31, the piston 21 moves rearward. As a result,
The stopper portions 32 of the inclined portion B are separated from each other, and the fulcrum portions of both levers are immovably held at positions separated from each other (see FIGS. 4 and 5).

In this state, in the area where the cam 16 does not lift, the fifth
As shown in the figure, the cam 16 and roller 17 are completely separated, and the torque fluctuation absorption function is eliminated.

As a result, the responsiveness of the engine in a high rotation range is improved, and an increase in friction and vibration can be prevented.

3 4 The configuration of the above embodiment does not indicate any structural limitations of the present invention, and the present invention essentially consists of a cam that rotates in synchronization with a crankshaft and a biasing force that applies a biasing force to the cam. Any structure may be used as long as it has a torque fluctuation absorbing mechanism having a structure including means and a control means for controlling the operation of the biasing force applying means to change the biasing force in accordance with engine operating conditions.

<Effects of the Invention> As explained above, according to the present invention, a biasing force is applied to the cam that rotates in synchronization with the crankshaft to generate torque fluctuations in the opposite phase to the torque fluctuations generated by the engine. In addition to controlling the biasing force to vary according to the engine operating conditions, for example, by acting to absorb torque fluctuations in the low rotational speed range of the engine,
The engine speed can be set low during idling, reducing the fuel consumption rate.For example, by canceling the torque fluctuation absorption effect in the high engine speed range, This is highly useful as it has the advantage of improving the responsiveness of the engine and preventing an increase in friction and vibration.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the torque fluctuation mitigation device for an internal combustion engine according to the present invention, (a) is a side sectional view, and (b) is (
a) A view in the direction of arrow A in the middle; Figure 2 is a diagram of fluctuating torques acting on the crankshaft and valve train and their combined torque diagram;
Figures 3 to 5 are front views for explaining the operation of the above embodiment, Figures 6 to 8 are diagrams for explaining the conventional torque fluctuation mitigation device, Figure 6 is a side view, and Figure 7 is a side view. 8 is a front view, and FIG. 8 is a diagram of fluctuating torques acting on the crankshaft and cam and their combined torque diagram. 10... Crankshaft 16... Cam 17.
...Roller 18...Lever 19...Tension spring 20...Hydraulic actuator 22...
...Hydraulic pressure chamber 24...Hydraulic pressure inlet pipe 25...On-off valve 26...Hydraulic pressure outlet pipe

Claims (1)

[Claims] The configuration includes a cam that rotates in synchronization with a crankshaft and a biasing force applying means that applies a biasing force to the cam, and the cam generates torque fluctuations in a phase opposite to torque fluctuations that occur in the crankshaft. 1. A torque fluctuation mitigation device for an internal combustion engine, characterized in that a torque fluctuation absorbing mechanism is provided, and a control means is provided for controlling the operation of the biasing force applying means to change the biasing force according to engine operating conditions.