JPH0640338U - Balance shaft device for internal combustion engine - Google Patents

Abstract

(57) [Summary] [Purpose] Suppresses the infiltration of oil from the bearing in the shaft case. [Structure] A balance shaft 22 accommodated in a shaft case 21 is arranged in parallel with a crankshaft so as to be immersed in the oil 11 in an oil pan. The journal portion 23 of the balance shaft 22 is provided with an oil sump portion 24 that is appropriately opened radially outward.
To form. An oil outlet hole 25 is formed in the shaft case 21 for guiding the oil scattered from the oil reservoir 24 to the outside.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a balance shaft device arranged in parallel with a crankshaft of an internal combustion engine.

[0002]

[Prior art]

 It is known that a recent internal combustion engine is equipped with a balance shaft device for preventing vibration caused by inertial force due to the mass of a reciprocating portion such as a piston (eg, Japanese Utility Model Publication No. 62-24150). .

As shown in FIG. 9, a balance shaft device 1 of this type conventionally supports a pair of or independent balance shafts 3 juxtaposed below a crankshaft 2 and a balance shaft 3 by appropriately covering the balance shaft 3. It also comprises a shaft case 4 attached to a cylinder block (not shown), and is rotated by a drive gear 6 meshing with a gear 5 provided on the crankshaft 2. The crankshaft 2 is appropriately provided with a pin 7 connected to a connecting rod (not shown), a journal 8 to be supported, a balance weight 9 and the like, and the gear 5 is attached to, for example, the central journal 8.

[0004]

[Problems to be solved by the device]

 By the way, below the crankshaft 2, an oil pan 10 for housing lubricating oil is provided. Therefore, in the balance shaft device 1, at least the lower part is submerged in the oil 11, and the oil 11 penetrates into the shaft case 4 through the gap between the bearings, which adversely affects the rotation of the balance shaft 3. In order to prevent this penetration, the balance shaft device 1 may be configured to be above the oil level (indicated by the chain double-dashed line in the figure), but this would increase the overall engine height and The mountability will deteriorate.

Therefore, it is necessary to equip the balance shaft device 1 with an oil pump to pump out the oil 11 accumulated in the shaft case 4, but due to this driving, friction loss increases, fuel consumption deteriorates, and the output is reduced. There was a problem of going down.

In view of the above circumstances, the present invention was devised to provide a balance shaft device for an internal combustion engine that can suppress oil from accumulating in the shaft case.

[0007] In addition to this, as a prior art related to the present invention, there is Japanese Utility Model Publication No. 57-43341.

[0008]

[Means for Solving the Problems]

 According to the present invention, the balance shaft housed in the shaft case is juxtaposed with the crankshaft so as to be immersed in the oil in the oil pan, and the journal portion of the balance shaft is provided with an oil reservoir portion that is appropriately opened radially outward. At the same time, the shaft case is formed with an oil drain hole for guiding the oil scattered from the oil sump to the outside.

[0009]

[Action]

 With the above structure, the oil sump stores the oil that has entered through the bearings of the shaft case and causes the oil to fly radially outward by the centrifugal force generated by the rotation of the balance shaft. The oil drain hole guides this oil to the outside of the shaft case and returns it to the oil pan.

[0010]

【Example】

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

FIG. 1 shows an embodiment of a balance shaft device for an internal combustion engine according to the present invention. In this balance shaft device, a balance shaft 22 housed in a shaft case 21 is juxtaposed to a crankshaft (not shown) so that the balance shaft 22 is immersed in the oil 11 in an oil pan. The sump portion 24 is configured by forming oil drain holes 25 in the shaft case 21.

The balance shaft 22 is composed of two balance portions 26 that are offset from the axial center C to one side in the radial direction, and three journal portions that are supported by the crankcase 21 via a metal bearing 27 and a rolling bearing 28. And a drive gear 29 that meshes with a gear (not shown) of the crank shaft is fixed to one end of the shaft with a mounting bolt 31 via a washer 30.

In the shaft case 21, a bearing portion 32 is formed with a member thickness corresponding to that of the journal portion 23, and a wall portion 33 that connects the bearing portion 32 and the journal portion 23 surrounds the outer circumference of the balance shaft 22, as shown in FIG. As described above, the balun shaft 22 is vertically divided into two parts (21a, 21b) at the axial center position and assembled. The lower shaft case 21b is formed with a wall portion 34 that surrounds the drive gear 29 axially outward, and only the upper side, which is the meshing side, is open.

As shown in FIG. 2, the oil sump portion 24 is defined by a flange-shaped protrusion 35 protruding radially outward at a corner position of the journal portion 23 separated from the metal bearing 27. The projection 35 and the peripheral wall of the journal portion 23 are continuous with each other on an appropriate curved surface. The oil sump portion 24 that follows the balance portion 26 is divided by a stepped protrusion 36. Further, in the present embodiment, in addition to the journal portion 23 at the shaft end portion, an oil sump portion 24 is similarly formed at the central journal portion 23.

The oil drain hole 25 is formed in an overhanging portion 37 attached to the bearing portion 32 so as to face the oil sump portion 24, and radially extends from a position inside the protrusion 35 as shown in FIG. It penetrates to the outer surface. In this embodiment, five are provided on the upper shaft case 21a, and two are provided relatively on the upper side of the lower shaft case 21b.

As shown in FIG. 1, the balance shaft device is provided with an oil pump 38 for returning the oil 11a accumulated at the bottom of the shaft case 21 into the oil pan, and the suction side thereof. A strainer pipe 39 extending to the bottom wall surface is attached, and a pipe 40 that opens downward outside the shaft case 21 is attached to the discharge side. The strainer pipe 39 is inserted into the shaft case 21 while being supported by a mounting hole 41 formed in the upper shaft case 21a.

Next, the operation of this embodiment will be described.

When the crankshaft is rotated by driving the engine, the balance shaft 22 rotates in synchronization with this, and the inertial force and the inertial couple force due to the mass of the reciprocating portion such as the piston are canceled to suppress the vibration caused thereby. The oil 11 in the oil pan lubricates the metal bearing 27 of the balance shaft 22 and then flows through the journal 23 and overflows to the oil sump 24 in the shaft case. If the balance shaft 22 is stopped, this oil drips downward, but if it is rotating, the oil also rotates due to the friction between the oil and the surface of the balance shaft 22, and centrifugal force acts on the protrusion 35. Along the radial direction. Then, this oil enters the oil drain hole 25 and is discharged to the outside of the shaft case 21. Further, the oil 11a accumulated at the bottom of the shaft case 21 without entering the oil discharge hole 25 is pumped out by the oil pump 38 which is appropriately driven and returned to the oil pan.

As described above, the oil sump portion 24 formed in the journal portion 23 of the balance shaft 22 and the oil drain hole 25 formed in the bearing portion 32 of the shaft case 22 transmit the oil transmitted through the metal bearing 27. Since the oil is discharged to the outside of the case by centrifugal force, the amount of oil 11a accumulated on the bottom of the shaft case 21 can be reduced, and the rotation of the balance shaft 22 can be prevented from being adversely affected.

Since the amount of the oil 11a accumulated in the shaft case 21 is significantly reduced, it is possible to reduce the driving force of the oil pump 38 for pumping the oil 11a, that is, the engine loss, and the fuel consumption is deteriorated. It is possible to install the balance shaft 22 under the oil level of the oil pan without any problem because the output does not decrease. Therefore, by providing the balance shaft device, the total height of the engine does not increase and the mountability on the vehicle does not deteriorate.

Further, the present invention has an extremely simple structure, can be easily applied to the conventional balance shaft, and is extremely versatile.

As the oil drain hole, in addition to the linear shape shown in FIG. 3, as shown in FIG. 5, an oil drain hole 42 having an oil receiving portion 41 whose inner opening is appropriately expanded, or As shown in FIG. 6, the oil drain hole 43 may be tilted along the rotational direction r of the balance shaft 22. If formed in this way, it is possible to capture more of the oil that has jumped out of the oil reservoir 24 and to let it go out.

FIGS. 7 and 8 show another embodiment of the present invention. In addition to the oil sump 24 and the oil drain hole 25, in order to prevent the oil overflowing from the bearing 27 from falling off, In addition, a step portion 53 protruding inward is formed at a location of the lower shaft case 52 facing the balance portion 26 of the balance shaft 51, and a labyrinth portion 54 is further formed. By doing so, it is possible to further reduce the amount of oil that accumulates at the bottom of the shaft case. Even if the labyrinth portion 54 is omitted and only the step portion 53 is provided, the amount of oil falling can be reduced.

[0024]

[Effect of device]

 In short, according to the present invention, the following excellent effects are exhibited.

The balance shaft has an oil reservoir that is appropriately opened radially outward, and an oil drain hole that guides the oil outward is formed in the shaft case. The oil in the oil pan can be prevented from accumulating in the shaft case by flying it out of the case, and the adverse effect on the rotation of the balance shaft can be prevented.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of a balance shaft device according to the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a sectional view taken along the line BB of FIG.

5 is a cross-sectional view showing a modified embodiment of the oil drain hole of FIG.

6 is a cross-sectional view showing another modified embodiment of the oil drain hole of FIG.

FIG. 7 is a side sectional view showing a main part of another embodiment of the present invention.

8 is a perspective view showing the lower crankcase of FIG. 7. FIG.

FIG. 9 is a side view showing a conventional balance shaft device.

[Explanation of symbols]

 11 Oil in Oil Pan 21 Shaft Case 22 Balance Shaft 23 Journal Part 24 Oil Pool 25 Oil Drain Hole

Claims (1)

[Scope of utility model registration request] 1. A balance shaft housed in a shaft case is juxtaposed with a crankshaft so as to be immersed in oil in an oil pan, and an oil sump portion is provided in a journal portion of the balance shaft and is appropriately opened radially outward. A balance shaft device for an internal combustion engine, characterized in that an oil outlet hole is formed in the shaft case for guiding the oil scattered from the oil reservoir to the outside.