JP2023180466A - Driving device for vehicle - Google Patents

Abstract

To provide a driving device for a vehicle capable of ensuring gas liquid separation of a lubricant even in a state that bubbles of the lubricant easily generate.SOLUTION: A driving device 10 for a vehicle includes a case 11 for storing a lubricant G, and a plurality of gear pairs 20 provided in the case 11 while kept into contact with the lubricant G. The case 11 has a gear chamber 13 for housing the plurality of gear pairs 20, and a breather chamber 12 partitioned from the gear chamber 13 via a drive unit retainer 40. The breather chamber 12 is communicated with the gear chamber 13 via a first oil passing hole 45 provided on a recessed portion 41b in a manner of being opened at a lower part with respect to an oil level OL of the lubricant G, and communicated with the external of the case 11 via an external communication passage 14 at an upper part with respect to the oil level OL of the lubricant G. When observed from an axial direction of the gear pairs 20, a first cross-sectional area along a vertical direction of an internal space 12a of the breather chamber 12 is larger than a second cross-sectional area of the plurality of gear pairs 20 along an intersection direction X intersecting the axial direction.SELECTED DRAWING: Figure 7

Description

The present invention relates to a vehicle drive device.

BACKGROUND ART Conventionally, as a technology related to a vehicle drive device, for example, the technology described in Patent Document 1 is known. Patent Document 1 discloses a breather chamber in which a part of the upper part of the drive case is partitioned as a structure for suppressing leakage of oil scraped up by the gears to the outside of the drive case.

Japanese Patent Application Publication No. 2020-186761

When a breather chamber is provided in a portion of the upper portion of the drive case as described above, the ability to separate gas and liquid of lubricating oil is limited. Therefore, for example, when the breather chamber of the prior art described above is applied to a vehicle drive device configured such that a plurality of gear pairs in contact with lubricating oil rotate at high speed, a large amount of air bubbles may be generated in the lubricating oil. In such a situation, there is a risk that gas-liquid separation may not be possible and a portion of the lubricating oil may leak out of the case.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle drive device that can ensure gas-liquid separation of lubricating oil even under conditions where bubbles are likely to occur in the lubricating oil.

A vehicle drive device according to one aspect of the present invention is a vehicle drive device including a case containing lubricating oil and a plurality of gear pairs arranged in contact with the lubricating oil within the case. has a gear chamber that accommodates a plurality of gear pairs, and a breather chamber that is partitioned from the gear chamber by a partition wall, and the breather chamber has a partition wall that opens below the level of the lubricating oil. It communicates with the gear chamber through an oil passage hole provided in the gear chamber, and communicates with the outside of the case through an external communication path above the lubricating oil level, when viewed from the axial direction of the gear pair. , the first cross-sectional area of the internal space of the breather chamber along the vertical direction is larger than the second cross-sectional area of the plurality of gear pairs along the cross direction intersecting the axial direction.

In the vehicle drive device according to one aspect of the present invention, in the gear chamber, the lubricating oil is stirred by rotation of a plurality of gear pairs arranged in contact with the lubricating oil. For example, when a plurality of gear pairs rotate at high speed, a large amount of bubbles are generated and the lubricating oil, which is a mixture of gas and liquid, moves from the gear chamber to the breather chamber through the oil passage hole. Here, the second cross-sectional area is related to the amount of stirring of lubricating oil in the gear chamber. That is, by configuring the breather chamber so that the first cross-sectional area is larger than the second cross-sectional area when viewed from the axial direction of the gear pair, the internal space of the breather chamber can accommodate the amount of stirring of lubricating oil in the gear chamber. It becomes easier to secure. Therefore, according to the vehicle drive device according to one aspect of the present invention, it is possible to ensure gas-liquid separation of lubricating oil even in a situation where bubbles of lubricating oil are likely to occur.

In one embodiment, the plurality of gear pairs may be arranged so as to be sandwiched between the oil passage hole and the external communication path in the vertical direction when viewed from the axial direction of the gear pairs. In this case, in the internal space of the breather chamber, the path length from the oil passage hole to the external communication path for separating the lubricating oil into gas and liquid is equal to or longer than the vertical dimension of the plurality of gear pairs. Thereby, it is possible to further ensure gas-liquid separation of the lubricating oil that has flowed into the breather chamber through the oil passage hole.

In one embodiment, the external communication path may extend along the axial direction of the gear pair in the upper part of the internal space of the gear chamber. In this case, since the external communication passage is arranged above the internal space of the gear chamber, the external communication passage is sufficiently far away from the lubricating oil in the vertical direction, which is a mixture of gas and liquid, in the internal space of the breather chamber. That will happen. This makes it easier to prevent lubricating oil in a mixed state of gas and liquid from flowing into the external communication path from the breather chamber, even in a situation where bubbles in the lubricating oil are likely to occur.

According to the present invention, it is possible to ensure gas-liquid separation of lubricating oil even in a situation where bubbles are likely to occur in lubricating oil.

FIG. 1 is a schematic perspective view showing the appearance of a vehicle drive device according to an embodiment. FIG. 2 is an exploded perspective view of the vehicle drive device for explaining a plurality of gear pairs. FIG. 2 is a perspective view of a drive unit case of the vehicle drive device shown in FIG. 1. FIG. FIG. 4 is a perspective view of the opposite side of the drive unit case of FIG. 3; FIG. 2 is a perspective view of a retainer of the vehicle drive device of FIG. 1. FIG. FIG. 2 is a perspective view of a differential carrier of the vehicle drive device shown in FIG. 1. FIG. FIG. 3 is a cross-sectional view showing cross-sectional areas of a plurality of gear pairs in FIG. 2 along a crossing direction. FIG. 2 is a perspective cross-sectional view showing a breather path of the vehicle drive system of FIG. 1. FIG.

Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and overlapping description will be omitted. For convenience of explanation, in each figure, the direction indicated by the arrow Fr is referred to as the "front side" or "front", the direction indicated by the arrow Rr is referred to as "rear side" or "rear", and the arrow designated Rh is referred to as the "front side" or "front". The direction in which it points is defined as "right side" or "rightward," the direction in which the arrow with symbol Lh points is defined as "left side" or "leftward," the direction in which the arrow in symbol U points in "upper side" or "above," and symbol D. The direction indicated by the arrow will be described as "downward" or "downward."

[Overview of vehicle drive system]
FIG. 1 is a schematic perspective view showing the appearance of a vehicle drive device according to an embodiment. FIG. 2 is an exploded perspective view of the vehicle drive device for explaining a plurality of gear pairs. The vehicle drive device 10 is a drive device used, for example, in an industrial vehicle such as an electric forklift. As shown in FIGS. 1 and 2, a motor 1 and a motor 2 are attached to the vehicle drive device 10. Motor 1 and motor 2 are, for example, three-phase AC motors of the same type. The vehicle drive device 10 combines the driving forces of the motors 1 and 2 and inputs the combined driving forces to one differential gear 4 (see FIG. 8) housed in the differential case 3. The vehicle drive device 10 transmits driving force to a pair of drive wheels 5 and 6 connected to a differential gear 4.

The vehicle drive device 10 includes a plurality of gear pairs 20. The motor 1 and the motor 2 are configured to rotate at the same speed via a plurality of gear pairs 20. Motor 1 and motor 2 are in a so-called direct connection state.

The plurality of gear pairs 20 include, for example, pinion gears 21, 22 and idler gears 23, 24, which are a gear pair for primary reduction, and idler gears 23, 24, and a driven gear 25, which are a gear pair for secondary reduction. have. The pinion gears 21 and 22, the idler gears 23 and 24, and the driven gear 25 are, for example, helical gears. The numbers of teeth of pinion gears 21 and 22 are equal to each other. Idler gears 23 and 24 have the same number of teeth.

The pinion gear 21 is attached to the output shaft of the motor 1 and meshes with the idler gear 23. The pinion gear 21 rotates the driven gear 25 via the idler gear 23. The pinion gear 22 is attached to the output shaft of the motor 2 and meshes with the idler gear 24 from the side opposite to the pinion gear 21 and the idler gear 23. The pinion gear 22 rotates the driven gear 25 via the idler gear 24. Thereby, the driving forces of motor 1 and motor 2 are combined at driven gear 25 by pinion gears 21 and 22 and idler gears 23 and 24.

The driven gear 25 is fitted into the differential drive shaft 7 at the axial center thereof, and rotates integrally with the differential drive shaft 7 (see FIG. 8). A bevel gear 8 is attached to one end of the differential drive shaft 7, and a fixing ring 9 is press-fitted to the other end. When the driven gear 25 rotates the differential drive shaft 7, the bevel gear 8 rotates the ring gear 4a of the differential gear 4. As a result, driving force is transmitted to the pair of drive wheels 5 and 6 connected to the differential gear 4. Note that the differential case 3 accommodates differential oil (not shown) in addition to lubricating oil G, which will be described later. In the differential case 3, a general breather plug 3a is attached to a through hole (not shown) formed on the upper surface of the reduced diameter portion 3b of the differential case 3 (see FIG. 1).

In the power transmission path of such a vehicle drive device 10, the differential gear 4 is located close to the drive wheels 5, 6, so the rotational speed from the motors 1, 2 is sufficiently reduced. In addition, since the differential case 3 has one input shaft and one pair of gears, the breather performance (ability to separate lubricating oil into gas and liquid) required for the differential case 3 is higher than that of conventional vehicle drive systems. Particularly high performance is not required.

However, in the power transmission path of the vehicle drive device 10, the rotation speed from the motors 1 and 2 is not reduced as much at the locations of the plurality of gear pairs 20 as the location of the differential gear 4. In particular, the pinion gears 21 and 22 are attached to the output shafts of the motors 1 and 2, as will be described later, and rotate at the same number of rotations as the number of rotations of the motors 1 and 2. Furthermore, since there are two input shafts and two pairs of gears at the location of the plurality of gear pairs 20, the number of gears increases compared to the case where there is one input shaft. Therefore, for example, when the motors 1 and 2 are operated at high rotation speeds (for example, 7000 rpm), the lubricating oil G is violently stirred and scattered by the plurality of gear pairs 20, and a large amount of air bubbles lubricate the parts of the plurality of gear pairs 20. This will occur in oil G. For example, in a typical conventional breather structure, there is a risk that the volume of the internal space of the breather chamber will be insufficient and gas-liquid separation will not be possible. Furthermore, even with a breather structure in which multiple breather chambers are connected, a film of lubricating oil may form in the passages due to a large amount of air bubbles, which may impede stable breather function (function of separating lubricating oil into gas and liquid). there were. Therefore, there is room for improvement in order to satisfy the breather performance required by a structure in which there are two or more input shafts and a plurality of gear pairs 20 rotate at high speed.

[Breather structure of vehicle drive system]
The breather structure of the vehicle drive device 10 will be described in detail below. FIG. 3 is a perspective view of the drive unit case of the vehicle drive device shown in FIG. 1. FIG. 4 is a perspective view of the opposite side of the drive unit case of FIG. 3. FIG. 5 is a perspective view of the retainer of the vehicle drive device of FIG. 1. FIG. FIG. 6 is a perspective view of the differential carrier of the vehicle drive system of FIG. 1. As shown in FIGS. 1 to 6, the vehicle drive device 10 includes a case 11 having a drive unit case 30 and a drive unit retainer 40. The drive unit case 30 and the drive unit retainer 40 are combined with a differential carrier 50.

FIG. 3 shows the drive unit case 30 seen from the rear, and FIG. 4 shows the drive unit case 30 seen from the front. As shown in FIGS. 2 to 4, the drive unit case 30 supports the motors 1, 2 and a portion of the plurality of gear pairs 20 (pinion gears 21, 22, idler gears 23, 24). The drive unit case 30 includes a base 31 , a pair of motor attachment parts 32 and 33 formed on the front side of the base 31 , a retainer attachment part 34 and a plurality of gear support parts 35 formed on the rear side of the base 31 . have.

The base portion 31 is a main body portion of the drive unit case 30, and includes a flat plate portion 31a extending in the left-right direction as a longitudinal direction. The flat plate portion 31a has a thickness such that it has a predetermined strength and rigidity to support the motors 1 and 2 and the gear pair 20.

The pair of motor attachment parts 32 and 33 are formed so as to be lined up in the left-right direction on the front side of the base part 31. The motor attachment parts 32 and 33 include, for example, outer circumferential fixing parts 32a and 33a for fixing the outer circumferential parts of the motors 1 and 2 on the output shaft side. The outer peripheral fixing parts 32a and 33a are cylindrical parts extending forward with the flat plate part 31a as the base end. Bolt holes 32b and 33b for fixing the outer circumferential parts of the motors 1 and 2 on the output shaft side are formed in the front end surfaces of the outer circumferential fixing parts 32a and 33a. The outer peripheral fixing parts 32a and 33a define recesses 32c and 33c corresponding to the outer peripheral shape of the motors 1 and 2 when viewed from the front. Central fixing parts 32d and 33d, which are recesses for supporting the central parts of the motors 1 and 2 on the output shaft side, are formed in the central parts of the recesses 32c and 33c. In the pair of motor mounting parts 32 and 33, the output shafts of the motors 1 and 2 are inserted into the through holes of the central fixing parts 32d and 33d, and the peripheries of the output shafts of the motors 1 and 2 are surrounded by the central fixing parts 32d and 33d. In the supported state, the outer peripheries of the motors 1 and 2 on the output shaft side are fixed to the outer periphery fixing parts 32a and 33a with bolts.

The retainer mounting portion 34 includes an outer peripheral wall portion 34a formed along the rear outer periphery of the base portion 31. The outer peripheral wall portion 34a has the flat plate portion 31a as its base end and extends rearward from the flat plate portion 31a by a predetermined first dimension D1. The outer peripheral wall portion 34a surrounds the plurality of gear support portions 35 when viewed from the rear. The outer peripheral wall portion 34a defines a recessed portion 34b whose bottom surface is the flat plate portion 31a. The bottom surface of the recess 34b has a larger area than a second cross-sectional area (described later, see FIG. 7) along the intersecting direction X that intersects (perpendicularly intersects) the axial direction of the plurality of gear pairs 20. In the retainer attachment portion 34, the drive unit retainer 40 is fixed to the rear end surface 34c of the outer peripheral wall portion 34a. Bolt holes 34d for fixing the drive unit retainer 40 are formed in the rear end surface 34c of the outer peripheral wall 34a.

The plurality of gear support parts 35 are formed so as to be lined up along the left-right direction in a portion surrounded by the outer peripheral wall part 34a on the bottom surface of the recess 34b. The plurality of gear support parts 35 include a plurality of arc wall parts 35a, 35b, 35c, and 35d that protrude rearward from the bottom surface of the recess 34b. Arc wall portions 35a, 35b, 35c, and 35d correspond to pinion gear 21, idler gear 23, idler gear 24, and pinion gear 22, respectively. A circular recess 36 is formed on the bottom surface of the recess 34b between the arcuate walls 35b and 35c so as to avoid interference with the other end of the differential drive shaft 7 and the fixing ring 9.

The arc wall portions 35a and 35d correspond to the back sides of the pair of central fixing portions 32d and 33d described above. In the arc wall portions 35a, 35d, the output shafts of the motors 1, 2 are exposed rearward, with the output shafts being inserted through the central fixing portions 32d, 33d. In this state, pinion gears 21 and 22 are attached to the output shafts of motors 1 and 2. The arc wall portions 35a and 35d surround the pinion gears 21 and 22 attached to the output shafts of the motors 1 and 2. The arc wall portions 35a and 35d indirectly support the pinion gears 21 and 22 via the central portions of the motors 1 and 2 on the output shaft side, respectively. The arcuate wall portion 35b is located between the arcuate wall portion 35a and the circular recess 36. The arcuate wall portion 35c is located between the arcuate wall portion 35d and the circular recess 36. Each of the arcuate walls 35b, 35c holds, for example, the outer peripheral surface of a bearing, and rotatably supports the idler gears 23, 24 via a shaft inserted through the bearing.

FIG. 5 shows the drive unit retainer 40 seen from the rear. The drive unit retainer 40 supports the remainder of the plurality of gear pairs 20 (driven gears 25) and partitions a breather chamber 12 and a gear chamber 13, which will be described later. The drive unit retainer 40 includes a base portion 41 and a differential carrier attachment portion 42 formed along the rear outer periphery of the base portion 41 .

The base portion 41 is a main body portion of the drive unit retainer 40, and includes a flat plate portion 41a extending in the left-right direction as a longitudinal direction. The flat plate portion 41a has a thickness such that it has a predetermined strength and rigidity to support the differential drive shaft 7.

The differential carrier mounting portion 42 includes an outer peripheral wall portion 42a formed along the rear outer periphery of the base portion 41. The outer peripheral wall portion 42a has the flat plate portion 41a as its base end and extends rearward from the flat plate portion 41a by a predetermined second dimension D2. In the differential carrier mounting portion 42, the differential carrier 50 is fixed to the rear end surface 42b of the outer peripheral wall portion 42a. Bolt holes 42c for fixing the differential carrier 50 are formed in the rear end surface 42b of the outer peripheral wall 42a.

The outer peripheral wall portion 42a defines a recessed portion 41b whose bottom surface is the flat plate portion 41a. A plurality of openings 41c and 41d are formed on the bottom surface of the recess 41b. The plurality of openings 41c and 41d are formed in pairs on the left and right in a portion surrounded by the outer peripheral wall 42a on the bottom surface of the recess 41b. The arcuate walls 35a and 35b are inserted through the opening 41c. The arc wall portions 35c and 35d are inserted through the opening 41d. A drive shaft holding hole 41e is formed in the center of the base 41 at the bottom of the recess 41b between the openings 41c and 41d. The drive shaft holding hole 41e holds, for example, the outer peripheral surface of a bearing, and rotatably supports the differential drive shaft 7 inserted through the bearing.

The opening 41c exposes the pinion gear 21 attached to the output shaft of the motor 1 and the idler gear 23 pivotally supported by the arcuate wall 35b to the recess 41b. The opening 41d exposes the pinion gear 22 attached to the output shaft of the motor 2 and the idler gear 24 pivotally supported by the arcuate wall 35c to the recess 41b. With the pinion gears 21, 22 and idler gears 23, 24 exposed in the recess 41b, the driven gear 25 is fitted into the axially central portion of the differential drive shaft 7 that is pivotally supported in the drive shaft holding hole 41e. As a result, in the recess 41b, the pinion gear 21 and the idler gear 23, the idler gear 23 and the driven gear 25, the pinion gear 22 and the idler gear 24, and the idler gear 24 and the driven gear 25 are in a state of meshing with each other, and when viewed from the rear, a plurality of gears The pair 20 is now surrounded by the outer peripheral wall 42a.

FIG. 6 shows the differential carrier 50 seen from the rear. The differential carrier 50 has a base portion 51 attached to the drive unit retainer 40 and a differential gear support portion 52 formed on the rear side of the base portion 51.

A plurality of bolt holes 51 a corresponding to the bolt holes 42 c of the drive unit retainer 40 are formed in the base portion 51 . The plurality of bolt holes 51a communicate with the bolt holes 34d of the retainer mounting portion 34 and the bolt holes 42c of the differential carrier mounting portion 42. Drive unit case 30, drive unit retainer 40, and differential carrier 50 are fixed to each other by inserting fixing bolts (not shown) into bolt holes 51a, 42c, and 34d and tightening them. Thereby, the accommodation space for the differential gear 4 and the gear chamber 13 are partitioned.

The differential gear support portion 52 is formed with a pair of left and right holding portions 52a. By fixing the cap (not shown) to the holding part 52a, a bearing (not shown) is held, and the left and right supported parts of the differential gear 4 are rotatably supported via the bearing. In this state, the differential case cover 53 is attached to cover the differential gear 4 (see FIG. 1). Thereby, in the differential case 3, the differential oil for lubricating the bevel gear 8 and the differential gear 4 can be accommodated in the accommodation space for the differential gear 4.

Note that a drive shaft holding hole 51b is formed in the base 51 of the differential carrier 50 (see FIG. 8). The drive shaft holding hole 51b holds, for example, the outer peripheral surface of a bearing, and rotatably supports the differential drive shaft 7 inserted through the bearing. With the drive shaft holding hole 51b supporting the bearing and the differential drive shaft 7, the housing space for the differential gear 4 is configured to be oil-tight with the gear chamber 13 (case 11). There is.

According to the case 11 (drive unit case 30 and drive unit retainer 40) as described above, the drive unit case 30 and the drive unit retainer 40 are fixed via the rear end surface 34c of the outer peripheral wall portion 34a of the retainer attachment portion 34, so that The recess 34b of the drive unit case 30 is closed by the drive unit retainer 40, and the space of the breather chamber 12 is defined by the drive unit case 30 and the drive unit retainer 40. Therefore, the case 11 has a breather chamber 12.

Further, by fixing the drive unit retainer 40 and the differential carrier 50 via the rear end surface 42b of the outer peripheral wall 42a of the differential carrier mounting portion 42, the recess 41b of the drive unit retainer 40 is closed by the differential carrier 50, and the drive unit The space of the gear chamber 13 is defined by the retainer 40 and the differential carrier 50. Therefore, the case 11 has a gear chamber 13 that accommodates a plurality of gear pairs 20. The breather chamber 12 is partitioned from the gear chamber 13 via a drive unit retainer 40 (partition wall), and is adjacent to the gear chamber 13 via the drive unit retainer 40 along the axial direction of the gear pair 20.

Here, the case 11 (gear chamber 13 and breather chamber 12) of the vehicle drive device 10 accommodates lubricating oil G that lubricates the plurality of gear pairs 20 of the gear chamber 13 (see FIGS. 7 and 8). The lubricating oil G is gear oil having a lower viscosity than the differential oil that lubricates the bevel gear 8 and the differential gear 4, for example. The lubricating oil G is injected into the case 11 from an oil supply port (not shown) provided at the top of the case 11 so as to reach a predetermined oil level. The predetermined oil level is the position of the oil level OL when a predetermined volume of lubricating oil G is injected into the case 11. The plurality of gear pairs 20 are arranged in the gear chamber 13 of the case 11 so as to be in contact with the lubricating oil G.

As shown in FIGS. 5 and 7, an oil passage hole 43 and a ventilation hole 44 are provided in the base 41 (bottom surface of the recess 41b) of the drive unit retainer 40. The oil passage hole 43 and the ventilation hole 44 are through holes that allow the gear chamber 13 and the breather chamber 12 to communicate with each other.

The oil passage hole 43 is provided in the drive unit retainer 40 so as to open below the oil level OL of the lubricating oil G. The oil passage hole 43 is formed, for example, on the lower side of the bottom surface of the recess 41b in the drive unit retainer 40. The oil passage hole 43 includes a first oil passage hole 45 provided at the central lower end of the gear chamber 13, and a second oil passage hole 46 provided in a pair on the left and right sides of the gear chamber 13 with the gear chamber 13 in between. But that's fine.

The first oil passage hole 45 is entirely opened below the oil level OL of the lubricating oil G. The first oil passage hole 45 may be opened to include an edge 45a that is continuous with the lower end inner wall surface 13a of the gear chamber 13. A reinforcing portion 41g may be formed around the first oil passage hole 45, which is continuous with the lower end inner wall surface 13a of the gear chamber 13 and continuous with the circular thick portion 41f around the drive shaft holding hole 41e. This reinforcing portion 41g functions as a reinforcing rib that connects the lower end inner wall surface 13a of the gear chamber 13 and the thick wall portion 41f, and the support rigidity of the differential drive shaft 7 by the drive shaft holding hole 41e is improved.

The second oil passage hole 46 may be opened in the shape of a long hole having a longitudinal direction along the up-down direction above the lower end inner wall surface 13a. The second oil passage hole 46 may be entirely opened below the oil level OL of the lubricating oil G. The upper edge of the second oil passage hole 46 may be located above the upper edge of the first oil passage hole 45 . The pair of left and right second oil passage holes 46 may open upwardly away from each other (in an inverted V-shape).

The ventilation hole 44 is provided in the drive unit retainer 40 so as to open above the oil level OL. The ventilation hole 44 is formed above the first oil passage hole 45 in the upper half of the internal space 13b of the gear chamber 13, for example. The ventilation hole 44 may be formed at a position sandwiched between a pair of left and right second oil holes 46 in the left-right direction. The ventilation hole 44 may be opened in the shape of a long hole having a longitudinal direction along the up-down direction.

The breather chamber 12 communicates with the outside of the case 11 via an external communication path 14 above the oil level OL of the lubricating oil G. The external communication passage 14 here is a cylindrical passage 15 extending along the axial direction of the gear pair 20 in the upper part of the gear chamber 13, as shown in FIGS. 5, 7, and 8. The cylindrical passage 15 is defined, for example, by a cylindrical wall portion 15a that is approximately elliptical and includes the upper end of the outer peripheral wall portion 42a of the drive unit retainer 40 when viewed from the axial direction of the gear pair 20. The cylindrical wall portion 15a defines an internal space 13b of the gear chamber 13 and an external communication path 14. The cylindrical passage 15 extends rearward from the base 41 along the axial direction of the gear pair 20 over the second dimension D2, similarly to the outer peripheral wall 42a of the drive unit retainer 40.

The external communication passage 14 includes, for example, a discharge passage 54 formed in the differential carrier 50, and the cylindrical passage 15 is connected to the discharge passage 54, thereby communicating with the outside of the case 11. The discharge passage 54 has a through hole 54a that opens at the top of the differential carrier 50, and a breather plug 55 is attached to the through hole 54a. Since the breather chamber 12 and the external communication path 14 have sufficient volume and path length, a general breather plug 55 similar to the breather plug 3a can be used.

The breather chamber 12 has a first cross-sectional area along the vertical direction of the internal space 12a of the breather chamber 12 when viewed from the axial direction of the gear pairs 20, and a second cross-sectional area along the cross direction X of the plurality of gear pairs 20. The structure is larger than the cross-sectional area. Here, the first cross-sectional area along the vertical direction corresponds to the cross-sectional area of the internal space 12a of the breather chamber 12 along the cross direction X. The first cross-sectional area may correspond to the area of the portion surrounded by the outer edge of the recess 34b of the retainer attachment portion 34 (see FIG. 3). The first cross-sectional area here corresponds to the area of the portion of the retainer attachment portion 34 surrounded by the outer peripheral wall portion 34a. The second cross-sectional area may correspond to the cross-sectional area of the gear that contacts the lubricating oil G among the plurality of gear pairs 20 along the intersecting direction X (see FIG. 7). The second cross-sectional area may correspond to the cross-sectional area of all the gears of the plurality of gear pairs 20 along the intersecting direction X. The second cross-sectional area here corresponds to the cross-sectional area of the pinion gears 21, 22, the idler gears 23, 24, and the driven gear 25 along the intersecting direction X (total area indicated by hatching SC in FIG. 7).

Further, the plurality of gear pairs 20 may be arranged so as to be sandwiched between the oil passage hole 43 and the external communication path 14 in the vertical direction viewed from the axial direction of the gear pair 20 (see FIG. 7). The plurality of gear pairs 20 here are arranged so as to be sandwiched between the first oil passage hole 45 and the cylindrical passage 15 in the vertical direction when viewed from the axial direction of the gear pairs 20. The external communication path 14 is arranged at the upper end of the internal space 12a of the breather chamber 12 (see FIG. 8). That is, by arranging the plurality of gear pairs 20 so as to be sandwiched between the first oil passage hole 45 and the cylindrical passage 15 in the vertical direction, the vertical dimension of the internal space 12a of the breather chamber 12 is equal to that of the gear chamber 13. This is larger than the vertical dimension of the internal space 13b.

[Effect]
In the vehicle drive device 10 configured as described above, the lubricating oil G is stirred in the gear chamber 13 by the rotation of the plurality of gear pairs 20 arranged in contact with the lubricating oil G. As shown in FIG. 8, for example, when a plurality of gear pairs 20 rotate at high speed, a large amount of bubbles are generated and the lubricating oil G, which is a mixture of gas and liquid, is transferred to the first oil passage hole 45. It moves from the gear chamber 13 to the breather chamber 12 via the (oil passage hole 43). The lubricating oil G that has moved to the breather chamber 12 is separated into gas and liquid in the internal space 12a of the breather chamber 12. The gas separated into gas and liquid from the lubricating oil G moves above the internal space 12a of the breather chamber 12, passes through the external communication passage 14 (cylindrical passage 15), and passes from the discharge passage 54 to the case via the breather plug 55. It is discharged to the outside of 11. The breather chamber 12 is partitioned from the gear chamber 13 via the drive unit retainer 40 (partition wall), and is separated from the internal space 13b of the gear chamber 13 where the lubricating oil G is stirred and bubbles of the lubricating oil G are generated. The interior space 12a of the breather chamber 12 in which the breather is carried out is largely separated. Therefore, gas-liquid separation in the internal space 12a of the breather chamber 12 is promoted. Here, the second cross-sectional area is related to the amount of stirring of the lubricating oil G in the gear chamber 13. That is, by configuring the breather chamber 12 so that the first cross-sectional area is larger than the second cross-sectional area when viewed from the axial direction of the gear pair 20, the breather can correspond to the amount of stirring of the lubricating oil G in the gear chamber 13. It becomes easier to secure the internal space 12a of the chamber 12. Therefore, according to the vehicle drive device 10, even in a situation where bubbles in the lubricating oil G are likely to occur, it is possible to ensure gas-liquid separation of the lubricating oil G.

According to the vehicle drive device 10, the plurality of gear pairs 20 are arranged so as to be sandwiched between the oil passage hole 43 and the external communication path 14 in the vertical direction viewed from the axial direction of the gear pairs 20. As a result, in the internal space 12a of the breather chamber 12, the path length from the oil passage hole 43 to the external communication path 14 for separating the lubricating oil G into gas and liquid is equal to or longer than the vertical dimension of the plurality of gear pairs 20. Become. Thereby, the gas-liquid separation of the lubricating oil G that has flowed into the breather chamber 12 through the oil passage hole 43 can be further ensured.

According to the vehicle drive device 10, the external communication path 14 extends along the axial direction of the gear pair 20 in the upper part of the internal space 13b of the gear chamber 13. As a result, the external communication passage 14 is disposed above the internal space 13b of the gear chamber 13, so that the external communication passage 14 is filled with lubricating oil G in a mixed state of gas and liquid in the internal space 12a of the breather chamber 12. It will be sufficiently far away from the top and bottom. This makes it easier to prevent the lubricating oil G in a mixed state of gas and liquid from flowing into the external communication path 14 from the breather chamber 12 even in a situation where bubbles are likely to occur in the lubricating oil G.

The breather chamber 12 communicates with the gear chamber 13 via an oil passage hole 43 provided in the drive unit retainer 40 so as to open below the oil level OL of the lubricating oil G. For example, the oil level OL in the breather chamber 12 and the gear chamber 13 is approximately the same when averaged over time. Therefore, in the internal space 12a of the breather chamber 12, the external communication passage 14 (cylindrical passage 15) is sufficiently spaced from the oil level OL in the vertical direction (here, equivalent to the depth of the oil level OL). Become. Therefore, compared to, for example, a conventional structure in which a breather chamber is provided in a part of the upper part of the drive case, the internal space 12a of the breather chamber 12 is enlarged, and gas-liquid separation in the internal space 12a of the breather chamber 12 is performed. will be further promoted.

Incidentally, a ventilation hole 44 is provided in the drive unit retainer 40 so as to open above the oil level OL. As a result, even if the internal pressure of the gear chamber 13 becomes high when, for example, lubricating oil G adheres to the vent hole 44 and forms a film, the internal pressure of the gear chamber 13 is transferred to the breather chamber 12 through the vent hole 44. The film of lubricating oil G can be eliminated. Therefore, it is possible to prevent the internal pressure of the gear chamber 13 from becoming too high, and it is possible to suppress an adverse effect on gas-liquid separation.

[Modified example]
Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above. The present invention can be implemented in various forms including the embodiments described above, with various changes and improvements based on the knowledge of those skilled in the art.

In the above embodiment, the vehicle drive device 10 is provided with two motors, and the gear pair 20 has five gears, but three or more motors may be provided, or the gear pair 20 has five gears. 20 may have six or more gears.

In the embodiment described above, the plurality of gear pairs 20 are arranged so as to be sandwiched between the first oil passage hole 45 and the external communication path 14 in the vertical direction viewed from the axial direction of the gear pairs 20. Not limited. For example, like the relationship between the second oil passage hole 46 and the driven gear 25, some of the gear pairs may not be completely sandwiched between the oil passage hole and the external communication path.

In the above embodiment, the external communication path 14 extends along the axial direction of the gear pair 20 in the upper part of the internal space 13b of the gear chamber 13, but is not limited thereto. For example, the external communication path 14 may be provided so as to pass through the outside of the gear chamber 13.

In the embodiment described above, by fixing the drive unit case 30 and the drive unit retainer 40 to each other, the recess 34b of the drive unit case 30 is closed by the drive unit retainer 40, and the space in the breather chamber 12 is closed by the drive unit case 30 and the drive unit retainer 40. was defined, but is not limited to this example. The breather chamber is partitioned from the gear chamber via a partition wall, and may be deformed into various shapes as long as it has a first cross-sectional area in the vertical direction that is larger than the second cross-sectional area. Further, the breather chamber may be arranged at a position that is not adjacent to the gear chamber along the axial direction of the gear pair. In this case, the first cross-sectional area along the up-down direction does not have to correspond to the cross-sectional area along the cross direction X of the internal space of the breather chamber.

In the embodiment described above, by fixing the drive unit retainer 40 and the differential carrier 50 to each other, the recess 41b of the drive unit retainer 40 is closed by the differential carrier 50, and the space in the gear chamber 13 is closed by the drive unit retainer 40 and the differential carrier 50. was defined, but is not limited to this example. The gear chamber may be deformed into various shapes as long as it accommodates a plurality of gear pairs arranged in contact with the lubricating oil within the case.

In the above embodiment, the vehicle drive device 10 is a drive device used for an industrial vehicle such as an electric forklift, but it can be used for other vehicles as long as the vehicle uses a battery as a power source to drive a motor. It may be.

DESCRIPTION OF SYMBOLS 10... Vehicle drive device, 11... Case, 12... Breather chamber, 12a... Internal space, 13... Gear chamber, 13b... Internal space, 14... External communication path, 15... Cylindrical passage (external communication path), 20... Gear pair, 40...Drive unit retainer (partition wall), 43...Oil hole, G...Lubricating oil, OL...Oil surface, X...Cross direction.

Claims (3)

A vehicle drive device comprising: a case containing lubricating oil; and a plurality of gear pairs disposed in the case in contact with the lubricating oil,
The case has a gear chamber that accommodates the plurality of gear pairs, and a breather chamber that is partitioned from the gear chamber via a partition,
The breather chamber communicates with the gear chamber through an oil passage hole provided in the partition wall so as to open below the oil level of the lubricating oil, and communicates with the gear chamber above the oil level of the lubricating oil. and communicates with the outside of the case via an external communication path,
When viewed from the axial direction of the gear pairs, a first cross-sectional area along the vertical direction of the internal space of the breather chamber is equal to a second cross-sectional area of the plurality of gear pairs along the cross direction intersecting the axial direction. A vehicle drive unit that is larger than its area. The vehicle drive device according to claim 1, wherein the plurality of gear pairs are arranged so as to be sandwiched between the oil passage hole and the external communication path in a vertical direction viewed from an axial direction of the gear pairs. . The vehicle drive device according to claim 1 or 2, wherein the external communication path extends along the axial direction of the gear pair in an upper part of the internal space of the gear chamber.

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