JP7480913B2 - Damper cooling structure for internal combustion engine - Google Patents

Description

This invention relates to a cooling structure that uses outside air to cool a disk-shaped damper (torsion damper) attached to the front end of an internal combustion engine's crankshaft.

A disk-shaped damper is sometimes attached to the front end of the crankshaft of an internal combustion engine, with an inner peripheral part fixed to the crankshaft and an outer peripheral part having an appropriate mass connected via an elastic material layer (rubber layer). This damper is designed to reduce the torsional vibration of the crankshaft, and may also be configured as a crankshaft pulley around which a belt is wound.

Since the rubber layer of such a damper is easily deteriorated by heat, it is preferable that the damper be equipped with some kind of cooling structure. Patent Document 1 discloses a cooling structure in which louvers serving as air inlets and air outlets are formed on the front surface of a cover that covers a timing belt pulley, facing each other at positions 180° apart on the pulley, so that air flows inside the cover as the pulley rotates.

However, in this conventional cooling structure, the louvers that serve as the air inlet and the louvers that serve as the air outlet are located on the same plane in the axial direction of the crankshaft, and the air that flows in through the louvers that serve as the air inlet runs along the front end face of the pulley and turns 180 degrees before being discharged from the louvers that serve as the air outlet. In other words, the air flow does not go around the pulley once, but merely flows near the end face of the pulley, and the pulley cannot be effectively cooled.

Japanese Utility Model Application Publication No. 59-79526

The damper cooling structure for an internal combustion engine according to the present invention comprises an internal combustion engine having a disk-shaped damper attached to a rotating shaft protruding from an end face of the engine body and a cover covering the damper, the cover being provided with an air inlet for directing air into the space within the cover by a pumping action accompanying the rotation of the damper and an air outlet for discharging air from the space, the air inlet and the air outlet being offset from each other in the axial direction of the crankshaft.

Because the air inlet and air outlet are offset from each other in the axial direction of the crankshaft, the air taken in through the air inlet flows in a spiral around the damper by the pumping action that accompanies the rotation of the damper, and is discharged from the air outlet after making at least one revolution. This allows for effective cooling of the damper.

1 is a side view of a front end portion of an internal combustion engine equipped with a damper cooling structure according to an embodiment of the present invention; FIG. 2 is a front view of the front end of the internal combustion engine equipped with a damper cover. FIG. 3 is a bottom view of the main part as seen from below in FIG. 2 . 3 is a cross-sectional view taken along line AA in FIG. 2. FIG. 4 is a front view of the front end of the internal combustion engine with the damper cover removed. FIG. 2 is a front view of the front end of the internal combustion engine illustrating the flow of airflow. FIG. 5 is a cross-sectional view similar to FIG. 4, showing a damper according to a second embodiment.

An embodiment of the present invention will be described in detail below with reference to the drawings. Figures 1 to 5 show the configuration of the front end portion of an internal combustion engine equipped with a damper cooling structure according to the present invention. The internal combustion engine of this embodiment is used, for example, as an internal combustion engine for generating electricity to drive a generator in a series hybrid vehicle. As shown in Figure 1, a metal chain cover 2 made of die-cast aluminum alloy or the like is attached to the cylinder block 1 with a plurality of bolts 3 so as to cover a chain chamber (not shown) for a valve gear on the front end face of the cylinder block 1. The front end of the crankshaft 4 passes through the chain cover 2, and as shown in Figure 5, a disk-shaped damper 5 is attached to the front end of the crankshaft 4. In this embodiment, the cylinder block 1 and the chain cover 2 correspond to the "engine body" in the claims.

The rear end of the crankshaft 4 (not shown) is connected to, for example, a generator (not shown) that is arranged in series with the internal combustion engine. In this specification, in accordance with common usage, regardless of whether the internal combustion engine is mounted on a vehicle, the side from which the output of the internal combustion engine is taken, i.e., the generator side, is referred to as the "rear" of the internal combustion engine, and the opposite side where the timing chain for the valve train is arranged is referred to as the "front" of the internal combustion engine. Unless otherwise specified in the following description, the words "front" and "rear" refer to the front and rear of the internal combustion engine.

The internal combustion engine in one embodiment is mounted on the vehicle in a so-called "horizontal" manner, that is, the axial direction of the crankshaft 4 is perpendicular to the fore-aft direction of the vehicle. In particular, in one embodiment, the internal combustion engine is mounted on the vehicle with the "front" side located on the right side of the vehicle. The central axis of the cylinder of the internal combustion engine is also generally aligned along the vertical direction of the vehicle, that is, the internal combustion engine is oriented as shown in Figure 2. Therefore, in this specification, the term "bottom" means the bottom side in Figure 2, unless otherwise specified.

As shown in Fig. 5, the damper 5 is composed of an inner peripheral member 8 fixed to the front end of the crankshaft 4 by a central bolt 7, a cylindrical outer peripheral member 9 having the mass required for damping action, and a cylindrical elastic member, such as a rubber member 10, interposed between the inner peripheral member 8 and the outer peripheral member 9. As shown in Fig. 4, the inner peripheral member 8 has a central boss 8a and a cylindrical rim 8b, and the rubber member 10 is firmly bonded to the outer peripheral surface of the rim 8b and the inner peripheral surface of the outer peripheral member 9.

When the internal combustion engine is viewed from the front as shown in Figure 5, the damper 5 (in other words, the crankshaft 4) rotates in a clockwise direction. The damper 5 suppresses the torsional vibration of the crankshaft 4.

Here, in a preferred embodiment, as shown in Figure 4, the rear end portion 9a of the outer peripheral surface of the outer peripheral member 9 is formed into a tapered surface whose diameter increases toward the rear.

A damper cover 11 that covers the damper 5 is attached to the front of the chain cover 2. This damper cover 11 also serves as a soundproof cover that blocks noise from the timing chain and other sources from inside the internal combustion engine, and is made of a synthetic resin material with excellent damping properties. In one embodiment, the chain cover 2 is attached to the cylinder block 1 by bolts 3 that secure the chain cover 2 to the cylinder block 1 in a so-called co-fastening manner.

The damper cover 11 has a cup-shaped portion, i.e., a cup portion 12, having an inner diameter corresponding to the diameter of the damper 5, and a flat portion 13 that is superimposed on the outer surface of the chain cover 2 around the cup portion 12. The cup portion 12 further has a cylindrical peripheral wall portion 14 that covers the peripheral surface of the damper 5, and a flat end wall portion 15 that covers the front end surface of the damper 5. Here, the cup portion 12 has a truncated cone shape with a relatively small diameter on the end wall portion 15 side, and therefore the inner peripheral surface 14a of the peripheral wall portion 14 that faces the peripheral surface of the damper 5 forms a tapered surface that is inclined so that the end wall portion 15 side has a relatively small diameter.

In addition, the peripheral wall 14 of the cup portion 12, which is molded as part of the damper cover 11, is not strictly continuous over 360°, and is molded with an open bottom side (indicated by the reference symbol 12a). In other words, when viewed from the front as shown in Figure 2, the cup portion 12 is shaped like a horseshoe, and the bottom side 12a does not have a peripheral wall 14.

In contrast to the configuration of the underside 12a of the cup portion 12, an oil tank portion 31 is formed at the lower end of the chain cover 2, protruding like a shelf toward the front of the internal combustion engine. This oil tank portion 31 forms an oil reservoir in which the space inside (on the cylinder block 1 side) (not shown) becomes part of the chain chamber, and includes a bottom wall 31a protruding forward from the plate-like portion of the chain cover 2, two side walls 31b and 31c, and a flat ceiling wall 31d, and further includes a front wall 31e that connects the front edges of the bottom wall 31a, the side walls 31b and 31c, and the ceiling wall 31d. In other words, the oil tank portion 31 is formed to protrude like an elongated box.

Here, the upper surface of the ceiling wall 31d of the oil tank section 31 is formed as a flat surface along a plane parallel to the axial direction of the crankshaft 4, and the damper cover 11 is attached along the upper surface of this ceiling wall 31d. The opening surface of the lower side 12a of the cup section 12 described above is covered by the upper surface of this ceiling wall 31d.

In addition, the front wall 31e of the oil tank section 31 is formed into a flat surface along a plane perpendicular to the axial direction of the crankshaft 4, and the outer surface of this front wall 31e is aligned so as to form the same plane as the outer surface of the end wall 15 of the damper cover 11 when combined with the damper cover 11, as shown in Figure 1.

Therefore, when the damper cover 11 is combined with the oil tank portion 31, the space within the cup portion 12 forms a space that surrounds the entire circumference of the damper 5 without being open on the underside side 12a.

The damper cover 11 surrounding the damper 5 in this manner is provided with an air inlet 21 for taking in cooling air from the outside into the space within the cup portion 12 by utilizing the pumping action that accompanies the rotation of the damper 5, and an air outlet 22 for discharging warm air from the space within the cup portion 12 to the outside.

The air inlet 21 is disposed downward at the center of the lower end of the end wall 15 of the cup portion 12. More specifically, a bulge 15a protruding forward is formed in the center of the lower end of the end wall 15 along the vertical direction, and the lower end of this bulge 15a protrudes forward from the ceiling wall 31d of the oil tank portion 31, forming the air inlet 21 that opens downward as shown in FIG. 4. Therefore, the air inlet 21 is located further forward than the front end surface of the damper 5 in the axial position of the crankshaft 4. It is desirable that the bulge 15a extend upward to a range that reaches the inner circumferential side of the rim 8b of the damper 5 as shown in FIG. 4.

As shown in Figures 1 and 2, the air outlet 22 is formed by cutting out a part of the peripheral wall 14 of the cup portion 12 in the shape of a window. The air outlet 22 is located adjacent to the air inlet 21 in the circumferential direction centered on the damper 5, and more specifically, is located adjacent to a position downstream of the air inlet 21 in the rotational direction of the damper 5. Also, in the axial direction of the crankshaft 4, the air outlet 22 is opened at the rearmost position of the peripheral wall 14. As shown in Figure 4, the air outlet 22 is located rearward of the front end surface of the damper 5 and faces the rear end portion of the outer peripheral member 9 of the damper 5, more specifically, the rear end 9a that forms a tapered surface.

Therefore, the air inlet 21 and the air outlet 22 are offset from each other in terms of their positional relationship along the axial direction of the crankshaft 4. The air inlet 21 is located relatively forward, and the air outlet 22 is located relatively rearward, so that they do not overlap with each other in the axial direction of the crankshaft 4.

In the configuration of this embodiment, the damper 5 rotates at high speed inside the damper cover 11 to obtain a pumping action, and air is taken in from the air inlet 21, while the air that has cooled the damper 5 and been warmed is discharged from the air outlet 22. Figure 6 shows the flow of air in the damper cover 11. A low-pressure area is generated near the center of the damper 5 by the centrifugal force caused by the high-speed rotation of the damper 5, and air flows into the cup portion 12 from the air inlet 21 as shown by the arrow F1 in Figure 6. The air that flows in from the air inlet 21 is forced by the rotation of the damper 5 and swirls along the inner circumferential surface 14a of the peripheral wall portion 14 of the cup portion 12 as shown by the arrow F2. Here, the air outlet 22 is located immediately downstream of the air inlet 21, but since the two are offset from each other in the axial direction of the crankshaft 4, as can be easily understood from Figure 4, the air that flows in from the air inlet 21 does not flow out directly to the air outlet 22. Therefore, the air flows in a spiral shape around the outer periphery of the cup portion 12, and after making at least one revolution, is discharged from the air outlet 22 as shown by the arrow F3. In other words, the air swirls at least 360° within the cup portion 12.

Conversely, the longitudinal offset relationship between the air inlet 21 and the air outlet 22 is set based on simulations, etc., so that air flowing in from the air inlet 21 does not immediately flow out of the air outlet 22 at the expected engine rotation speed.

In this way, the cooling air flows around the entire circumference of the damper 5, which effectively cools the damper 5. Also, when viewed in the axial direction of the crankshaft 4, the air flows from the front of the damper 5 to the rear of the damper 5, crossing the damper 5 from front to rear, so the entire damper 5 can be effectively cooled.

In the above embodiment, the inner circumferential surface 14a of the peripheral wall portion 14 of the cup portion 12 is formed into a tapered surface, so that the air flow subjected to centrifugal force is guided rearward by the inclination of the tapered surface. This promotes the exhaust of air from the air outlet 22 located at the rear end of the space in the cup portion 12, resulting in a smoother flow of air through the cup portion 12. In other words, the tapered shape of the peripheral wall portion 14 guides the swirling flow in the axial direction from the front air inlet 21 to the rear air outlet 22, promoting the flow.

In the above embodiment, the rear end 9a of the outer peripheral member 9 of the damper 5 forms a tapered surface facing the air outlet 22, and the swirling flow flowing in the axial direction is guided to the outer peripheral side, facilitating the exhaust of air through the air outlet 22. As a result, the air flows smoothly through the cup portion 12.

In particular, by combining the tapered surface of the peripheral wall portion 14 of the cup portion 12 with the tapered surface of the rear end portion 9a on the damper 5 side, a spiral flow is more reliably formed within the cup portion 12.

When the internal combustion engine is mounted on a vehicle, the right side of Fig. 2 faces the front of the vehicle, and the left side of Fig. 2 faces the rear of the vehicle. Therefore, the air outlet 22 in the cup portion 12 opens toward the rear of the vehicle. Therefore, the flow of air trying to exit from the air outlet 22 is not obstructed by the wind generated by the vehicle moving.

Furthermore, the air inlet 21 is surrounded by the bulge 15a and faces downward, and the front wall 31e of the oil tank section 31 is located below the air inlet 21. Therefore, water droplets and other foreign matter that have been scattered toward the damper cover 11 from above and below the vehicle are less likely to enter the air inlet 21.

Although one embodiment of the present invention has been described above in detail, the present invention is not limited to the above embodiment and various modifications are possible. For example, in the above embodiment, only the rear end 9a of the outer circumferential surface of the damper 5 is partially tapered, but the entire outer circumferential surface may be tapered.

In addition, as in the second embodiment shown in Figure 7, the outer peripheral surface of the damper 5 may be a simple cylindrical surface rather than a tapered surface.

Similarly, the peripheral wall 14 of the cup portion 12 may be a simple cylindrical shape without being tapered. Even with such a cylindrical shape, a spiral flow can be formed that travels from the air inlet 21 to the air outlet 22 after making one revolution.

In addition, the chain cover 2 may be configured not to have an oil tank portion 31, and the cup portion 12 may surround the entire circumference of the damper 5, including the lower portion.

The present invention can also be applied to a damper that doubles as a crankshaft pulley around which a belt is wrapped.

Claims (6)

In an internal combustion engine, a disk-shaped damper is attached to a rotating shaft protruding from an end face of an engine body, and a cover is provided to cover the damper.
the cover is provided with an air inlet for introducing air into the space within the cover by a pump action accompanying rotation of the damper, and an air outlet for discharging air from the space,
the air inlet and the air outlet are offset from each other in the axial direction of the crankshaft,
The air outlet is disposed adjacent to the air inlet downstream in the circumferential direction so that air flowing in from the offset air inlet turns 360° before being discharged.
Damper cooling structure for an internal combustion engine. In an internal combustion engine, a disk-shaped damper is attached to a rotating shaft protruding from an end face of an engine body, and a cover is provided to cover the damper.
the cover is provided with an air inlet for introducing air into the space within the cover by a pump action accompanying rotation of the damper, and an air outlet for discharging air from the space,
the air inlet and the air outlet are offset from each other in the axial direction of the crankshaft,
the cover has a cup-shaped portion that covers an end face and a peripheral surface of the damper,
An inner circumferential surface of the cup-shaped portion forms a tapered surface inclined in a direction along the crankshaft axial direction so as to guide the swirling flow from the air inlet to the air outlet.
Damper cooling structure for an internal combustion engine. In an internal combustion engine, a disk-shaped damper is attached to a rotating shaft protruding from an end face of an engine body, and a cover is provided to cover the damper.
the cover is provided with an air inlet for introducing air into the space within the cover by a pump action accompanying rotation of the damper, and an air outlet for discharging air from the space,
the air inlet and the air outlet are offset from each other in the axial direction of the crankshaft,
a tapered surface inclined in a direction to guide the swirling flow from the air inlet to the air outlet along the crankshaft axial direction is provided on at least a part of an outer circumferential surface of the damper in an axial direction;
Damper cooling structure for an internal combustion engine. When viewed in the crankshaft axial direction, the air inlet is located relatively away from the engine body, and the air outlet is located relatively close to the engine body.
The damper cooling structure for an internal combustion engine according to any one of claims 1 to 3. The lower surface side of the damper is covered by the cover or another member of the internal combustion engine,
The air inlet is provided downward in a portion of the cover that covers an end face of the damper.
The damper cooling structure for an internal combustion engine according to any one of claims 1 to 4 . The internal combustion engine is mounted on the vehicle with a crankshaft axial direction perpendicular to the front-rear direction of the vehicle,
The air outlet opens toward the rear of the vehicle.
The damper cooling structure for an internal combustion engine according to any one of claims 1 to 5 .

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