Lubricating device of vehicle transmission system

In a catch tank, a partition wall is formed that extends along a vehicle front-rear direction and divides the catch tank in a vehicle width direction in a vehicle-mounted state, which helps prevent oil in the catch tank from flowing unevenly to one of a first space and a second space even when the oil surface of the oil tilts during turn of the vehicle, for example. As a result, an appropriate amount of oil required for lubrication is supplied through a second lubrication hole regardless of tilt of the vehicle or turn of the vehicle.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2022-112062 filed on Jul. 12, 2022, incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a lubricating device included in a vehicle transmission system.

2. Description of Related Art

Many structures have been hitherto proposed as lubricating devices that lubricate lubrication-requiring parts, such as gears and bearings, housed inside a vehicle transmission system. For example, Japanese Unexamined Patent Application Publication No. 2016-89860 (JP 2016-89860 A) discloses a structure in which oil swept up by a gear is temporarily stored in a catch tank, and the oil in the catch tank is supplied to lubrication-requiring parts through a lubrication hole.

SUMMARY

A lubricating device including a catch tank like that of JP 2016-89860 A may have difficulty supplying a required amount of oil to lubrication-requiring parts when the oil surface in the catch tank tilts due to tilt of the vehicle or a centrifugal force applied during turn of the vehicle.

The present disclosure has been contrived in the context of the above-described situation, and an object thereof is to provide a structure of a lubricating device of a vehicle transmission system including a catch tank that can supply an appropriate amount of oil to lubrication-requiring parts even when the oil surface in the catch tank tilts during travel of the vehicle.

The gist of the present disclosure is as follows. (a) A lubricating device of a vehicle transmission system, the lubricating device including a predetermined gear housed inside a case and a catch tank provided inside the case, above the predetermined gear in a vehicle-mounted state, and having a structure in which oil swept up by rotation of the predetermined gear is caught by the catch tank, wherein: (b) the catch tank has a shape elongated in a vehicle front-rear direction in the vehicle-mounted state; (c) in the catch tank, a partition wall is formed that extends along the vehicle front-rear direction and divides the catch tank in a vehicle width direction in the vehicle-mounted state; (d) as the inside of the catch tank is divided by the partition wall, a first space and a second space separated in the vehicle width direction are formed; (e) a first lubrication hole communicating with the first space and a second lubrication hole communicating with the second space are formed on a side of the catch tank in a longitudinal direction opposite from a side where oil swept up by the predetermined gear flows in; and (f) an inclined part that is inclined vertically downward while extending away from the partition wall in the vehicle width direction is formed on the side of the catch tank in the longitudinal direction opposite from the side where oil swept up by the predetermined gear flows in, in at least one of a portion forming the first space and a portion forming the second space.

According to the present disclosure, in the catch tank, the partition wall is formed that extends along the vehicle front-rear direction and divides the catch tank in the vehicle width direction in the vehicle-mounted state, which helps the oil in the catch tank from flowing unevenly to one of the first space and the second space even when the oil surface of the oil tilts during turn of the vehicle, for example, Further, the inclined part that is inclined vertically downward while extending away from the partition wall in the vehicle width direction is formed in at least one of the portion of the catch tank that forms the first space and the portion thereof that forms the second space, so that oil is retained at least in the space on the side where the inclined part is formed even when the oil surface of the oil in the catch tank tilts during turn of the vehicle, for example. As a result, oil can be supplied to lubrication-requiring parts through the first lubrication hole and the second lubrication hole even when the oil surface in the catch tank tilts during travel.

DETAILED DESCRIPTION OF EMBODIMENTS

An embodiment of the present disclosure will be described below in detail with reference to the drawings. In the following embodiment, the drawings are simplified or deformed as necessary and parts are not necessarily correctly depicted in terms of their dimensional ratios, shapes, etc.

FIG.1is a view schematically showing the inside of a vehicle transmission system10(hereinafter, “transmission system10”) to which the present disclosure is applied. The upper side in the sheet ofFIG.1corresponds to a vertically upper side in a vehicle-mounted state. The right side in the sheet ofFIG.1corresponds to a vehicle front side in the vehicle-mounted state. A direction perpendicular to the sheet ofFIG.1corresponds to a vehicle width direction in the vehicle-mounted state. The vehicle-mounted state in this specification is a state when the vehicle is on a flat road.

The transmission system10is applied to, for example, a battery electric vehicle having an electric motor (not shown) as a motive power source. Inside a case12of the transmission system10, an output gear14, a counter gear16, and a differential ring gear18are housed. The differential ring gear18corresponds to the predetermined gear of the present disclosure.

The output gear14is connected to, for example, the electric motor (not shown) such that power can be transmitted, and is disposed so as to be rotatable around a rotational axis CL1. The counter gear16is disposed so as to be rotatable around a rotational axis CL2. The differential ring gear18is disposed so as to be rotatable around a rotational axis CL3. The counter gear16and the differential ring gear18are meshed with each other. The differential ring gear18is integrally formed with a differential case22aof a well-known differential device22(seeFIG.2).

A catch tank20is provided vertically above the counter gear16and the differential ring gear18in the vehicle-mounted state. The catch tank20is disposed along part of an outer circumference of the counter gear16and part of an outer circumference of the differential ring gear18, and has a shape elongated in a vehicle front-rear direction in the vehicle-mounted state.

FIG.2is a schematic view of the differential ring gear18as seen in the vehicle-mounted state from a rear side in a vehicle advancing direction. As shown inFIG.2, the catch tank20is disposed vertically above the differential ring gear18in the vehicle-mounted state. In this embodiment, the dimension of the differential ring gear18in the vehicle width direction and the dimension of the catch tank20in the vehicle width direction are substantially equal dimensions.

Turning back toFIG.1, oil is stored at a vertically lower part of the case12, and when the differential ring gear18rotates clockwise as indicated by the black arrow during forward travel, the oil stored at the lower part of the case12is swept upward by the differential ring gear18. The blank arrows indicate the flow of the oil swept up. When the oil swept up is discharged through a gap between an inner wall surface of the case12and the catch tank20, this oil is caught by the catch tank20. The oil caught by the catch tank20moves toward the vehicle front side. Then, the oil is discharged through a first lubrication hole32aand a second lubrication hole32bindicated by dashed lines. The discharged oil is supplied to lubrication-requiring parts, such as gears and bearings. The first lubrication hole32aand the second lubrication hole32bare through-holes that are respectively formed in wall portions (of a second vertical wall30to be described later) forming both ends in the vehicle width direction and extend through these wall portions. The first lubrication hole32aand the second lubrication hole32bare formed at a lower part of the catch tank20in the vertical direction in the vehicle-mounted state.

FIG.3andFIG.4are both perspective views of the catch tank20. The vehicle width direction and the vehicle front-rear direction indicated inFIG.3andFIG.4both indicate directions in the vehicle-mounted state.

The catch tank20is composed of a guide part20athat extends so as to be elongated in the vehicle front-rear direction in the vehicle-mounted state, and a tank part20bthat is connected to one end of the guide part20ain a longitudinal direction. The tank part20bextends toward both sides in the vehicle width direction.

The guide part20ais formed by a first bottom wall24that forms a lower part in the vertical direction in the vehicle-mounted state, and a pair of first vertical walls26a,26bthat is erected vertically upward from both edges of the first bottom wall24in the vehicle width direction.

The first bottom wall24is disposed vertically above the counter gear16and the differential ring gear18in the vertical direction in the vehicle-mounted state, and has a shape conforming to the shape of the outer circumference of the counter gear16and the shape of the outer circumference of the differential ring gear18. The first bottom wall24has a predetermined dimension in the vehicle width direction.

The pair of first vertical walls26a,26bis erected vertically upward from both edges of the first bottom wall24in the vehicle width direction. The pair of first vertical walls26a,26bextends so as to be elongated in the vehicle front-rear direction respectively along the edges of the first bottom wall24. The pair of first vertical walls26a,26bis formed so as to face each other. As the pair of first vertical walls26a,26bis formed, oil swept up by rotation of the differential ring gear18flows into the catch tank20from a leading end of the guide part20a. In other words, the oil swept up is caught by the catch tank20.

The tank part20bis connected to the side of the guide part20ain the longitudinal direction opposite from the side where the oil swept up flows in. The tank part20bextends toward both sides in the vehicle width direction in the vehicle-mounted state. The tank part20bincludes a second bottom wall28that forms a lower part in the vertical direction in the vehicle-mounted state, and the second vertical wall30that is erected vertically upward so as to surround an outer edge of the second bottom wall28. The second bottom wall28corresponds to the bottom wall of the present disclosure.

The second bottom wall28has a rectangular shape extending along the vehicle width direction in the vehicle-mounted state. A center portion of the second bottom wall28in the vehicle width direction is connected to an end portion of the first bottom wall24.

The second vertical wall30surrounds the outer edge of the second bottom wall28except for the portion where the first bottom wall24and the second bottom wall28are connected to each other. Of both end portions of the second vertical wall30in the surrounding direction, one end portion is connected to the first vertical wall26aand the other end portion is connected to the first vertical wall26b. As a result, a T-shaped space is formed inside the catch tank20by the guide part20aand the tank part20b. The first lubrication hole32aand the second lubrication hole32bshown inFIG.1are respectively formed in the wall portions of the second vertical wall30that form both ends in the vehicle width direction.

A first protrusion35athat covers the opening of the first lubrication hole32aand a second protrusion35bthat covers the opening of the second lubrication hole32bare formed on the second vertical wall30. Oil having flowed into the catch tank20passes through the guide part20aand the tank part20b, and is then discharged to an outside of the catch tank20through the first lubrication hole32aand the second lubrication hole32band supplied to lubrication-requiring parts, such as gears and bearings, housed inside the case12. Thus, a lubricating device42that supplies oil to those lubrication-requiring parts is configured with the catch tank and the differential ring gear18included.

When the vehicle turns, for example, the oil in the catch tank20may flow unevenly to one side in the vehicle width direction and the oil may fail to be supplied through one of the first lubrication hole32aand the second lubrication hole32b. As a countermeasure, a partition wall34that divides the inside of the catch tank20in the vehicle width direction is formed at the center of the guide part20aand the tank part20bof the catch tank20in the vehicle width direction.

The partition wall34is erected vertically upward from the first bottom wall24and the second bottom wall28in the vehicle-mounted state. The partition wall34is formed so as to extend along the vehicle front-rear direction and divide the inside of the catch tank20in the vehicle width direction in the vehicle-mounted state. As the inside of the catch tank20is divided by the partition wall34, a first space36and a second space38separated in the vehicle width direction are formed inside the catch tank20. Each of the first space36and the second space38is an L-shaped space. In this relation, the first space36communicates with the first lubrication hole32aand the second space38communicates with the second lubrication hole32b. The first lubrication hole32ais formed in a wall portion of the second vertical wall30that is located on the side of the first space36and faces the partition wall34, and the second lubrication hole32bis formed in a wall portion of the second vertical wall30that is located on the side of the second space38and faces the partition wall34.

Forming the partition wall34helps prevent the oil stored in the catch tank from flowing unevenly to one side of the tank part20bin the vehicle width direction even when the oil surface of the oil tilts while the vehicle travels so as to turn, for example. Thus, it helps prevent the situation where oil fails to be supplied through one of the first lubrication hole32aand the second lubrication hole32b.

Here, as shown inFIG.2, a helix angle α is formed in the differential ring gear18. Accordingly, when oil is swept up by the differential ring gear18, the oil is swept up along the tooth flank of the differential ring gear18and therefore scatters in the direction indicated by the arrow inFIG.2. As a result, the amount of oil flowing into the first space36that is located on the side in the vehicle width direction where the oil swept up by the differential ring gear18scatters becomes larger than the amount of oil flowing into the second space38that is located on the side in the vehicle width direction opposite from the side where the oil scatters.

As a countermeasure, to equalize the amounts of oil flowing into the first space36and the second space38, a portion of the partition wall34that is located on the side in the longitudinal direction where the oil swept up flows in is offset toward the first space36(or the first vertical wall26a) relative to the center of the pair of first vertical walls26a,26blocated at both ends of the catch tank20in the vehicle width direction. Further, in this embodiment, the portion of the partition wall34that is located on the side in the longitudinal direction where the oil swept up flows in is offset toward the first space36(or the first vertical wall26a) relative to a centerline CLG of the differential ring gear18in the vehicle width direction. The first vertical walls26a,26bcorrespond to the walls of the present disclosure that are located at both ends of the catch tank in the vehicle width direction.

Thus, as shown inFIG.2, an oil inflow width w1in the first space36becomes smaller than an oil inflow width w2in the second space38on the side of the guide part20ain the longitudinal direction where the oil flows in. This results in an increase in the amount of oil that is part of the oil swept up by the differential ring gear18and flows into the second space38. In this relation, it becomes also possible to equalize the ratio between the oil flowing into the first space36and the oil flowing into the second space38. The amount of offset of the partition wall34is obtained beforehand through experiment or design. For example, the amount of offset is set to such a value that the ratio between the oil flowing into the first space36and the oil flowing into the second space38becomes substantially equal.

Further, as shown inFIG.3, an inclined part40that is inclined vertically downward while extending away from the partition wall34in the vehicle width direction is formed on the side of the catch tank20in the longitudinal direction opposite from the side where oil flows in, in a portion that forms the second space38, i.e., a portion of the tank part20bof the catch tank20that forms the second space38. Specifically, the inclined part40that is inclined vertically downward while extending away from the partition wall34in the vehicle width direction is formed in the second bottom wall28of the catch tank20that extends in the vehicle width direction from the partition wall34toward the second lubrication hole32b. Thus, the second bottom wall28that extends in the vehicle width direction from the partition wall34toward the second lubrication hole32bis located farther vertically downward as it extends farther away from the partition wall34.

In this configuration, even when the amount of oil flowing in on the side of the second space38becomes small, the oil is retained in the tank part20bon the side of the second space38and oil to be discharged through the second lubrication hole32bis secured. As a result, even in the second space38in which the amount of oil flowing in tends to be smaller than that in the first space36, oil to be retained in the second space38can be secured. In this relation, the lubrication performance of the lubricating device42can be secured, and also the size of the catch tank20can be reduced. An angle of inclination θ (seeFIG.4) formed by the inclined part40and a horizontal plane intersecting each other in the vehicle-mounted state is set to be equal to or larger than a predetermined angle β (θ≥β) that is obtained beforehand through experiment or design. For example, the predetermined angle β is set to a lower limit threshold in a range of angle in which an amount of oil equal to or larger than a predetermined amount is retained in the tank part on the side of the second space38even when oil has become uneven due to turn of the vehicle or tilt of the vehicle.

As has been described above, according to this embodiment, the partition wall34that extends in the vehicle front-rear direction and divides the catch tank20in the vehicle width direction in the vehicle-mounted state is formed in the catch tank20, which helps prevent the oil in the catch tank20from flowing unevenly to one of the first space36and the second space38even when the oil surface of the oil tilts during turn of the vehicle, for example. Further, the inclined part40that is inclined vertically downward while extending away from the partition wall34in the vehicle width direction is formed in the portion of the catch tank20that forms the second space38, so that oil is retained in the second space38located on the side where the inclined part40is formed even when the oil surface of the oil in the catch tank20tilts during turn of the vehicle, for example. As a result, oil can be supplied to the lubrication-requiring parts through the second lubrication hole32beven when the oil surface in the catch tank20tilts during travel.

Since the portion of the partition wall34that is located on the side of the catch tank20in the longitudinal direction where oil swept up by the differential ring gear18flows in is offset toward the first space36relative to the center of the pair of first vertical walls26a,26blocated at both ends of the catch tank20in the vehicle width direction, an appropriate amount of oil flows in also on the side of the second space38, and the amounts of oil flowing into the first space36and the second space38are equalized. Further, since the angle of inclination θ formed by the inclined part40and a horizontal plane in the vehicle-mounted state intersecting each other is set to be equal to or larger than the predetermined angle θ that is set beforehand, an appropriate amount of oil is secured in the second space38regardless of turn of the vehicle or tilt of the vehicle.

While the embodiment of the present disclosure has been described in detail above based on the drawings, the present disclosure having other aspects is also applicable.

For example, in the above-described embodiment, the inclined part40that is inclined vertically downward while extending away from the partition wall34in the vehicle width direction is formed in the portion of the catch tank20that forms the second space38. However, the present disclosure is not necessarily limited to this aspect. For example, the inclined part40that is inclined vertically downward while extending away from the partition wall34in the vehicle width direction may be formed in the portion of the catch tank20that forms the first space36, or the inclined part40may be formed in both the portions of the catch tank20that form the first space36and the second space38.

While the helix angle α is formed in the differential ring gear18in the above-described embodiment, the helix angle α need not necessarily be formed. In this case, the partition wall34located on the side where oil swept up by the differential ring gear18flows in need not necessarily be offset, and the partition wall34may be formed between the pair of first vertical walls26a,26bin the vehicle width direction.

While the first lubrication hole32aand the second lubrication hole32bare formed in the second vertical wall30forming a portion of the tank part20bin the above-described embodiment, the first lubrication hole32aand the second lubrication hole32bmay instead be formed in the second bottom wall28.

The embodiment having been described above is merely one embodiment, and the present disclosure can be implemented with various modifications and improvements made to its aspects based on the knowledge of those skilled in the art.