JPH10280973A - Blancer mechanism for internal combustion engine, and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce vibration and vehicle booming noise by rotating a balance shaft in the range where rotational frequency of an internal combustion engine increases vehicle booming noise, and to improve fuel consumption and output torque by stopping rotation of the balance shaft in the range where rotational frequency of an internal combustion engine does not so increase vibration or vehicle booming noise. SOLUTION: The balancer mechanism 1 includes first and second balance shafts 4, 7, and a rotation transmitting device 12 which consists of a clutch mechanism 20, a driving sprocket 3, a chain 11, and first and second sprockets 6, 9. When rotational frequency of an internal combustion engine is more than intermediate value, the clutch mechanism 20 is cut and balance shafts 4, 7 are stopped. When rotational frequency of the internal combustion engine is less than intermediate value, the clutch mechanism 20 is turned on and balance shafts 4, 7 are rotated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a balancer mechanism for balancing inertial force generated by a reciprocating motion of a piston or the like of an internal combustion engine, and a driving method thereof.

[0002]

2. Description of the Related Art In an internal combustion engine of an automobile, an inertial force generated by a reciprocating motion of a piston or the like causes vibration and noise (mainly a vehicle muffled sound). In order to reduce the inertial force, the reciprocating motions of the plurality of pistons are shifted from each other at an optimal timing, so that the inertial forces generated for the respective pistons cancel each other. However, in the case of, for example, a four-cylinder internal combustion engine, a secondary component of the inertial force remains unbalanced, and as a result, vibration and muffled sound cannot be sufficiently reduced.

In order to reduce this secondary component, a balancer mechanism 40 as shown in FIGS. 7 and 8 has conventionally been employed. The balancer mechanism 40 includes a drive sprocket 42 fixed to a crankshaft 41 for taking out the rotation of the internal combustion engine and integrally rotating, and first and second eccentric weights 44 and 47, respectively.
First and second balance shafts 43 and 46 having
First and second sprockets 45 and 48, which are fixed to these and rotate integrally, and sprockets 42 and 4
5 and 48, and an idler sprocket 50 for engaging the first sprocket 45 with the outside of the chain 49.

When the crankshaft 41 rotates, the rotation is transmitted to the driving sprocket 42 → the chain 49 → the first and second sprockets 45 and 48, and the first balance shaft 43 is doubled in the opposite direction to the crankshaft 41. , And the second balance shaft 46 rotates at a double speed in the same direction with respect to the crankshaft 41. As a result, the secondary component of the inertial force is canceled, and vibration and muffled sound are reduced.

[0005]

However, the balancer mechanism 40 always transmits the rotation of the crankshaft 41 to the first and second balance shafts 43 and 46 regardless of the rotational speed of the internal combustion engine. Was driven to rotate,
There were the following problems.

In an internal combustion engine provided with a balancer mechanism 40,
As described above, there is an advantage that vibration and muffled sound can be reduced, but a part of the output taken out from the crankshaft 41 is partly output from the first and second balance shafts 43 and 46.
There is a demerit that the fuel consumption and the output torque are reduced because it is used for rotational driving of the motor.

FIG. 5 is a graph showing the relationship between the rotational speed of the internal combustion engine and the sound pressure level. Curve b in FIG.
Indicates an internal combustion engine having the balancer mechanism 40, and a curve c indicates an internal combustion engine having no balancer mechanism. As shown in the figure, the rotation speed of the internal combustion engine is set to a middle rotation speed (middle speed range,
000 rpm), the vibration and the muffled sound increase sharply (60 dB to 75 d at the sound pressure level of the curve c).
B) Therefore, the advantage of the balancer mechanism 40 greatly exceeds the disadvantage.

However, when the rotation speed of the internal combustion engine is lower than the medium rotation speed, the vibration and the muffled sound of the vehicle are small and are not so significant. Therefore, there is almost no merit of the balancer mechanism 40, and only substantial demerits. The area where the number of rotations is equal to or lower than the medium number of revolutions is the most frequent area for driving in an urban area in average car driving, and the disadvantage here is a serious problem. For example, in an internal combustion engine with a displacement of 2 liters, the engine provided with the balancer mechanism 40 has a reduction in fuel consumption of 2-3% and a reduction in output torque of 1-2% as compared with the engine not provided with the balancer mechanism 40. Can be seen. this is,
The same applies to a balancer mechanism using a belt, a gear, or the like as the rotation transmitting device.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and reduce the vibration and the vehicle muffled sound by rotating the balance shaft in a region where the rotational speed of the internal combustion engine increases the vibration and the vehicle muffled sound. Provided is a balancer mechanism for an internal combustion engine and a method thereof, in which the rotation of the balance shaft is stopped to improve fuel economy and output torque in a region where the rotational speed of the internal combustion engine does not significantly increase vibration or muffled noise. Is to do.

[0010]

To achieve the above object, a balancer mechanism for an internal combustion engine according to the present invention comprises a balance shaft rotatably supported in parallel with a crankshaft for taking out the rotation of the internal combustion engine, and a crankshaft. A rotation transmission device for transmitting the rotation of the shaft to the balance shaft to rotate the balance shaft, and turning on and off the rotation transmission device according to the number of revolutions of the internal combustion engine to rotate the balance shaft and stop the rotation. A switching mechanism is provided.

Here, examples of the "rotation transmission device" include a device using a sprocket and a chain, a device using a gear and a belt, and a device using meshing gears.

Examples of the "clutch mechanism" include a hydraulic type such as a multi-plate clutch and an electromagnetic type such as an electromagnetic clutch. The clutch mechanism may be provided near the crankshaft of the rotation transmission device, or may be provided near the balance shaft.

Preferably, the on / off of the clutch mechanism is controlled by a computer based on a detection value from a rotation speed sensor of the internal combustion engine.

[0014] More preferably, the on / off is controlled by a computer based on a detection value from a rotation speed sensor of the internal combustion engine and in addition to a detection value from a vehicle speed sensor or an oil temperature sensor.

Further, according to the method of driving a balancer mechanism of an internal combustion engine of the present invention, a balance shaft rotatably supported in parallel with a crankshaft for taking out the rotation of the internal combustion engine, and transmitting the rotation of the crankshaft to the balance shaft. A rotation transmission device for rotating the balance shaft by rotating the balance shaft by turning on and off a clutch mechanism provided in the rotation transmission device according to an operating condition such as a rotation speed of the internal combustion engine. And its pause.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments in which the present invention is embodied in a balancer mechanism of a four-cylinder internal combustion engine of an automobile will be described below with reference to FIGS.
It will be described based on. The balancer mechanism 1 includes first and second balance shafts 4, 7 rotatably supported in parallel with a crankshaft 2 for taking out the rotation of the internal combustion engine. First and second eccentric weights 5 and 8 are provided. At the end of the crankshaft 2,
The driving sprocket 3 is fixed via a clutch mechanism 20, and the first and second sprockets 6 whose diameters are の of the driving sprocket 3 are attached to the ends of the first and second balance shafts 4, 7. , 9 are fixed so as to rotate integrally with the first and second balance shafts 4, 7, respectively.

Drive sprocket 3, second sprocket 9
An endless annular chain 11 is wound around and engaged with an idler sprocket 10 separately provided,
The first sprocket 6 is engaged with the outside of the chain 11.

The clutch mechanism 20 includes two friction plates 21 and
1 which are turned on and off by coming and going with each other. The on / off state of the clutch mechanism 20 is controlled by the computer 15 based on the detection value from the rotation speed sensor 16 of the internal combustion engine and taking into account the detection value from the vehicle speed sensor 17 or the oil temperature sensor 18.

The clutch mechanism 20, the driving sprocket 3, the chain 11, and the first and second sprockets 6,
9 constitutes a rotation transmission device 12, which transmits the rotation of the crankshaft 2 to the first and second balance shafts 4, 7 in the following manner.

First, the rotation speed of the internal combustion engine is 3000 rpm.
In the following cases, the computer 15 disconnects the clutch mechanism 20 based on the detection value from the rotation speed sensor 16.
In this state, as shown in FIG. 2, the friction plates 21 and 21 are separated from each other, and the rotation of the crankshaft 2 is
Therefore, the first and second balance shafts 4, 7 are at rest.

When the rotation speed of the internal combustion engine becomes 3000 rpm or more, the computer 15 turns on the clutch mechanism 20 based on the detection value from the rotation speed sensor 16. However,
In the computer 15, a detection value from the vehicle speed sensor 17 or the oil temperature sensor 18 is also taken into account. That is, even if the rotation speed of the internal combustion engine is 3000 rpm or more, the vehicle speed is 6
The clutch mechanism 20 is turned on after reaching 0 km / h or until the oil temperature reaches 80 ° C. Conversely,
Even if the rotational speed of the internal combustion engine drops to 3000 rpm or less,
Vehicle speed remains above 60km / h or oil temperature is 80 ℃
If the above remains, the clutch mechanism is not immediately turned off. This is to prevent a frequent on / off operation of the clutch mechanism 20 by providing a time lag, and to switch between the rotational drive of the first and second balance shafts 4 and 7 and the suspension thereof at an optimal timing.

When the clutch mechanism 20 is engaged, as shown in FIG. 3, the friction plates 21 and 21 come into contact with each other, and the rotation of the crankshaft 2 is transmitted to the drive sprocket 3. As a result, the rotation of the crankshaft 2 is transmitted from the driving sprocket 3 → the chain 11 → the first and second sprockets 6 and 9, and the first balance shaft 4 rotates at a double speed in the opposite direction to the crankshaft 2, The second balance shaft 7 rotates at a double speed in the same direction with respect to the crankshaft 2.

FIG. 5 is a graph showing the relationship between the rotational speed of the internal combustion engine and the sound pressure level, as also used in the conventional example. A curve a in the figure shows an internal combustion engine provided with the balancer mechanism 1. As is clear from the figure, the curve a indicates that the rotation speed of the internal combustion engine is a medium rotation speed (medium speed range, for example, 3000 rpm).
Above m), it substantially overlaps with a curve b (an internal combustion engine without a conventional balancer mechanism), and below a middle rotational speed, it substantially overlaps with a curve c (an internal combustion engine without a balancer mechanism).

According to the balancer mechanism 1 of the present embodiment, as shown in FIG. 5, the region where the rotation speed of the internal combustion engine is equal to or higher than the medium rotation speed and where the vibration and the muffled sound are sharply increased (the curve c). At a sound pressure level of 60 dB to 75 dB), the clutch mechanism 20 is engaged, so that the first and second balance shafts 4 and 7 are driven to rotate, thereby enjoying the advantages of the conventional balancer mechanism, and vibrating / vehicle. The muffled sound can be reduced.

On the other hand, in a region where the rotational speed of the internal combustion engine is equal to or lower than the medium rotational speed and the vibration and the muffled sound are small, the clutch mechanism 20 is disengaged, so that the rotational speeds of the first and second balance shafts 4 and 7 are reduced. Driving is stopped, and the disadvantages of the conventional balancer mechanism can be eliminated to improve fuel efficiency and output torque.

The present invention is not limited to the above-described embodiment, but may be embodied with appropriate modifications without departing from the spirit of the invention, for example, as follows. (1) In the above embodiment, one clutch mechanism 20 is provided near the crankshaft 2, but as shown in FIG. 6, one clutch mechanism 20 may be provided near the first and second balance shafts 4, 7. According to this configuration, the rotation of the crankshaft 2 is always transmitted from the driving sprocket 3 → the chain 11 → the first and second sprockets 6,9. However, the clutch mechanism 20,
When 20 is off, the rotation is idling, which is not transmitted to the first and second balance shafts 4,7. Therefore, similarly to the above embodiment, it is possible to improve the fuel efficiency and the output torque. (2) Sprockets 3, 6, 9, 10 and chain 11
Instead, a gear and a belt, or meshing between gears may be used. (3) The present invention may be embodied in an internal combustion engine other than four cylinders. In that case, the number of the balance shafts and their rotation directions and rotation speeds are also changed.

[0027]

As described above in detail, according to the balancer mechanism for an internal combustion engine according to the first aspect, the balance shaft is rotationally driven in a region where the number of revolutions of the internal combustion engine increases vibration and muffled noise. In a region where the number of revolutions of the internal combustion engine does not increase the vibration or the muffled sound of the internal combustion engine, the driving of the balance shaft is stopped to improve the fuel consumption and the output torque. It has an excellent effect.

In addition to the above effects, according to the balancer mechanism for an internal combustion engine according to the second aspect, even if the present invention is applied to a balancer mechanism having a plurality of balance shafts (for example, for a four-cylinder internal combustion engine), It is sufficient to provide one clutch mechanism to switch between the rotational driving of the balance shaft and the rest thereof.

According to the balancer mechanism for an internal combustion engine according to the third aspect, when the present invention is applied to a balancer mechanism having only one balance shaft (for example, for a five-cylinder internal combustion engine), one clutch mechanism is provided. Is enough.

In addition to the above effects, according to the balancer mechanism for an internal combustion engine according to the fourth aspect, the clutch mechanism can be easily turned on and off according to the rotation speed of the internal combustion engine.

Further, according to the balancer mechanism for an internal combustion engine according to claim 5, frequent on / off of the clutch mechanism is prevented,
It is possible to switch between the rotational driving of the balance shaft and the suspension thereof at an optimal timing.

Further, the same effect as in the first aspect can be obtained by the driving method of the balancer mechanism of the internal combustion engine according to the sixth aspect.

[Brief description of the drawings]

FIG. 1 is a schematic front view showing a balancer mechanism according to an embodiment of the present invention.

FIG. 2 is a main part side view of FIG. 1 as viewed from the II side, showing a state in which a clutch mechanism used in the balancer mechanism is disengaged.

FIG. 3 is a side view of a main part of FIG. 1 as viewed from the side III, showing a state in which a clutch mechanism used in the balancer mechanism is engaged.

FIG. 4 is a flowchart illustrating a method of rotationally driving a balance shaft used in the balancer mechanism.

FIG. 5 is a graph showing a relationship between a rotational speed and a sound pressure level of an internal combustion engine or the like provided with the balancer mechanism.

FIG. 6 is a main part side view showing a balancer mechanism according to another embodiment.

FIG. 7 is a schematic front view showing a conventional balancer mechanism.

FIG. 8 is a main part side view of FIG. 7 showing the balancer mechanism, as viewed from the side of VIII.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Balancer mechanism 2 Crankshaft 3 Drive sprocket 4 First balance shaft 6 First sprocket 7 Second balance shaft 9 Second sprocket 11 Chain 15 Computer 16 Speed sensor 17 Vehicle speed sensor 18 Oil temperature sensor 20 Clutch mechanism

Claims (6)

[Claims] 1. A balance shaft rotatably supported in parallel with a crankshaft for extracting rotation of an internal combustion engine, and a rotation transmitting device for transmitting rotation of the crankshaft to the balance shaft to rotate the balance shaft. A balancer mechanism for an internal combustion engine, wherein a clutch mechanism for switching between rotation driving of the balance shaft and suspension thereof by switching on and off according to the rotation speed of the internal combustion engine is provided in the rotation transmission device. mechanism. 2. The balancer mechanism for an internal combustion engine according to claim 1, wherein said clutch mechanism is provided near a crankshaft of said rotation transmitting device. 3. The balancer mechanism for an internal combustion engine according to claim 1, wherein said clutch mechanism is provided near a balance shaft of said rotation transmitting device. 4. The balancer mechanism for an internal combustion engine according to claim 1, wherein the on / off of the clutch mechanism is controlled by a computer based on a detection value from a rotation speed sensor of the internal combustion engine. 5. The on / off state of the clutch mechanism is controlled by a computer based on a detection value from a rotation speed sensor of the internal combustion engine and in addition to a detection value from a vehicle speed sensor or an oil temperature sensor. 4. A balancer mechanism for an internal combustion engine according to claim 3. 6. A balance shaft rotatably supported in parallel with a crankshaft for extracting rotation of an internal combustion engine, and a rotation transmitting device for transmitting rotation of the crankshaft to the balance shaft to rotate the balance shaft. A method for driving the balancer mechanism, wherein a clutch mechanism provided in the rotation transmission device is switched on and off in accordance with an operating condition such as a rotation speed of the internal combustion engine to switch between rotation driving of the balance shaft and suspension thereof. A method for driving a balancer mechanism of an internal combustion engine, comprising: