Lubrication structure of gear mechanism

Abstract

To supply oil to a gear device using a stepped pinion type planetary gear mechanism efficiently with a simple structure.SOLUTION: A lubrication structure of a gear device includes: a reduction gear mechanism 3 having a stepped pinion 7 in which a large diameter pinion 7a configured to engage with a sun gear 5 and a small diameter pinion 7b configured to engage with a ring gear 6 are integrally formed, and a carrier 8 supporting the stepped pinon 7; a differential case 12 disposed at the inner peripheral side of a revolution track of the stepped pinion 7; and a differential gear mechanism 4 disposed in the differential case 12. Further, when the differential case 12 rotates, an oil 2 which has lubricated the differential gear mechanism 4 in the differential case 12 is supplied to the stepped pinion 7 of the reduction gear mechanism 3. In an outer peripheral side portion of the differential case 12, lubrication oil passages 22, 23 penetrating through the differential case 12 are respectively provided at positions corresponding to the large diameter pinion 7a and the small diameter pinion 7b in a rotation axis direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a lubrication structure for supplying lubricating oil to a gear device, particularly a gear device using a stepped pinion type planetary gear mechanism.

Background Art

[0002] Patent Document 1 describes a lubrication structure for a gear device aimed at efficiently and appropriately supplying oil with a simple configuration to a high surface pressure portion of a gear mechanism. The lubrication structure of the gear device described in this Patent Document 1 includes a planetary gear mechanism having a stepped pinion in which a large-diameter pinion meshing with a sun gear and a small-diameter pinion meshing with a ring gear are integrally formed, and a carrier that supports the stepped pinion, and a differential rotation mechanism disposed on the inner peripheral side of the revolution orbit of the stepped pinion and supplied with lubricating oil from an oil supply portion. When the differential rotation mechanism rotates, the oil supplied to the differential rotation mechanism to lubricate the differential rotation mechanism is supplied to a bearing between the carrier and the stepped pinion through the outer peripheral portion of the differential rotation mechanism. Further, in the lubrication structure of the gear device described in this Patent Document 1, a guide rib for guiding the oil supplied to the bearing to the stepped pinion is provided on the outer peripheral portion of the differential rotation mechanism.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The lubrication structure for a gear device described in Patent Document 1 above is applicable, for example, to a differential gear for a vehicle. A differential gear for a vehicle has a so-called differential case (differential gear case), and side gears, differential pinions, and reduction gears are arranged inside the differential case. That is, the differential rotation mechanism and planetary gear mechanism that constitute the gear mechanism are housed and arranged inside the differential case. Therefore, in the lubrication structure for a gear device described in Patent Document 1, oil supplied from the oil pump into the differential case lubricates the differential rotation mechanism through oil passages formed in the pinion shaft. Furthermore, the oil that has lubricated the differential rotation mechanism and bearings is supplied to the gear meshing portion of the stepped pinion via guide ribs formed on the outer circumference of the differential rotation mechanism. Therefore, according to the lubrication structure for a gear device described in Patent Document 1, the stepped pinion can be efficiently lubricated with a simple structure that only requires the provision of protruding guide ribs.

[0005] However, the amount of oil supplied and the direction in which it is sprayed and supplied vary depending on conditions such as the amount of oil remaining in the differential case, the rotational speed of the differential case, and the oil level in the housing of the transaxle or motor unit into which the differential case is incorporated. Therefore, it is difficult to control the amount of oil required for lubrication, and it is not easy to reliably and efficiently supply oil to the gear meshing part of the stepped pinion. In addition, since the oil guided into the differential case is discharged out through the weight-reducing holes in the differential case, it is necessary to maintain the oil level in the housing above a certain level in order to secure the amount of oil required for lubrication. As a result, if the oil level is kept high, the agitation loss inside the housing increases.

[0006] Thus, for gear systems using a stepped pinion planetary gear mechanism, such as the differential gear for vehicles described above, there was still room for improvement in order to supply oil more efficiently and appropriately with a simple structure.

[0007] This invention was conceived in response to the technical problems described above, and aims to provide a lubrication structure for a gear system using a stepped pinion planetary gear mechanism that can supply oil efficiently and more appropriately with a simple configuration. [Means for solving the problem]

[0008] To achieve the above objective, this invention provides a reduction gear mechanism comprising a planetary gear mechanism having a sun gear with external teeth, a ring gear with internal teeth, a stepped pinion in which a large-diameter pinion that meshes with the sun gear and a small-diameter pinion with a smaller diameter than the large-diameter pinion that meshes with the ring gear are integrally formed, and a carrier that supports the stepped pinion so that it can rotate and revolve; a differential case arranged coaxially with the reduction gear mechanism on the inner circumference side of the orbital path of the stepped pinion, which holds lubricating oil supplied from a predetermined oil supply unit and rotates when torque is transmitted from the reduction gear mechanism; and a rotating member housed and arranged within the differential case, which distributes the torque input to the differential case to two relatively rotatable rotating members arranged coaxially. A gear device lubrication structure comprising a differential gear mechanism that reaches and enables differential rotation of the two rotating members, wherein when the differential case rotates, the oil supplied to the differential case and used to lubricate the differential gear mechanism is supplied to the reduction gear mechanism, specifically to the rotating sliding part between the carrier and the stepped pinion of the reduction gear mechanism, thereby lubricating the reduction gear mechanism, wherein the differential case is characterized in that, on the outer peripheral portion (around the outer peripheral portion) of the differential case, lubrication oil passages are formed that penetrate between the inner surface of the differential case and the outer surface of the differential case to supply the oil to the large-diameter pinion and the small-diameter pinion, respectively, at positions corresponding to the teeth of the large-diameter pinion and the teeth of the small-diameter pinion in the direction of the rotation axis.

[0009] In this invention, the differential case may be configured such that, when the flow rate of the oil supplied to the differential case is defined as the inflow flow rate and the flow rate of the oil flowing out of the lubrication passage is defined as the outflow flow rate, the outflow flow rate is less than the inflow flow rate. Specifically, when the flow rate of the oil flowing out of parts of the differential case other than the lubrication passage is defined as the leakage flow rate, the differential case may be configured such that the sum of the outflow flow rate and the leakage flow rate is approximately equal to the inflow flow rate, that is, a balance is struck between the amount of oil supplied to the differential case and the amount of oil discharged from the differential case to the stepped pinion.

[0010] Furthermore, the differential case in this invention may be provided with sealing members (for example, oil seals, O-rings, or portions that cover weight-reducing holes) in areas where the oil supplied to the differential case may leak out of places other than the lubrication oil passages, thereby suppressing the leakage of the oil. [Effects of the Invention]

[0011] In the lubrication structure of the gear device of this invention, lubricating oil is supplied to the gear device, which consists of a reduction gear mechanism using a stepped pinion type planetary gear mechanism and a differential gear mechanism arranged in a differential case, for example, by being pumped from an oil pump or flowing from other lubricated parts. In this case, lubrication may also serve as cooling by the oil. The oil supplied to the gear device from an oil supply part such as an oil pump or other lubricated parts first flows into the differential case, is held inside the differential case, and lubricates the differential gear mechanism arranged inside the differential case. The differential case in the lubrication structure of the gear device of this invention does not have, for example, weight-reducing holes that are often used in conventional configurations, and is configured to hold a certain amount of oil inside the differential case. Therefore, the oil supplied from the oil supply part and held inside the differential case flows to the outer circumference (around the outer circumference) of the differential case due to the centrifugal force generated when the differential case rotates. Furthermore, in the lubrication structure of the gear device of this invention, the differential case has lubrication passages formed on its outer circumference for supplying oil to the stepped pinions of the reduction gear mechanism. The lubrication passages are through holes or through openings formed at positions corresponding to the teeth of the large-diameter pinion and the small-diameter pinion in the direction of the differential case's rotation axis. As a result, the oil that moves to the outer circumference of the differential case as it rotates is reliably supplied to the large-diameter and small-diameter pinions of the stepped-pinion planetary gear mechanism, efficiently lubricating them. The oil supplied to the stepped pinions in this manner then lubricates the rotating sliding parts between the carrier and the stepped pinions.

[0012] Therefore, according to the lubrication structure of the gear device of this invention, by providing a lubrication oil passage with a simple configuration, lubricating oil can be supplied efficiently and more appropriately to a gear device using a stepped pinion type planetary gear mechanism. [Brief explanation of the drawing]

[0013] [Figure 1]Figure 1 is a diagram illustrating the configuration of the lubrication structure of the gear device of this invention, and is a cross-sectional view showing the gear device targeted by this invention (a reduction gear mechanism using a stepped pinion type planetary gear mechanism, and a differential gear mechanism arranged in a differential case), as well as the lubrication oil passages. [Figure 2] Figure 2 is a diagram showing the detailed configuration (shape, arrangement, etc.) of the lubrication oil passages in the lubrication structure of the gear mechanism of this invention, and is a schematic diagram showing the view as indicated by arrow A in Figure 1. [Modes for carrying out the invention]

[0014] Embodiments of this invention will be described with reference to the drawings. Note that the embodiments shown below are merely examples of how this invention can be implemented and do not limit the invention.

[0015] Figures 1 and 2 show an example of a lubrication structure for a gear device in an embodiment of the present invention. The lubrication structure 1 shown in Figures 1 and 2 is subject to lubrication by lubricating oil 2 and comprises a reduction gear mechanism 3 and a differential gear mechanism 4, which correspond to the "gear device" in an embodiment of the present invention. As will be described later, Figure 1 shows an embodiment in which the differential gear mechanism 4 constitutes the "differential device" of the vehicle, and the reduction gear mechanism 3 constitutes a "reduction mechanism" that amplifies the torque transmitted to the "differential device".

[0016] The reduction gear mechanism 3 is constructed using a so-called "stepped pinion type planetary gear mechanism." Specifically, the reduction gear mechanism 3 includes a sun gear 5, a ring gear 6, a stepped pinion 7, and a carrier 8.

[0017] The sun gear 5 is an external gear and is formed on the outer circumference of the sun gear shaft 9, or is attached to the outer circumference of the sun gear shaft 9. The sun gear 5 and the sun gear shaft 9 rotate together. In the embodiment shown in Figure 1, a driving torque is transmitted to the sun gear shaft 9 from a predetermined driving force source (not shown). That is, the sun gear shaft 9 is the "input shaft" of the reduction gear mechanism 3. The sun gear shaft 9 is a hollow rotating shaft, and the first rotating shaft 17 (one of the drive shafts), which will be described later, is arranged in its hollow portion.

[0018] The ring gear 6 is an internal gear and is arranged coaxially with the sun gear 5. The ring gear 6 is fixed to a predetermined "fixing member" in a way that prevents rotation. In the embodiment shown in Figure 1, the ring gear 6 is fixed to the overall case 10 that houses both the reduction gear mechanism 3 and the differential gear mechanism 4. Furthermore, as will be described later, the reduction gear mechanism 3 is constructed using a stepped pinion 7, and therefore the ring gear 6 is positioned offset from the sun gear 5 in the direction of the rotation axis AL (left-right direction in Figure 1).

[0019] The stepped pinion 7 consists of a large-diameter pinion 7a and a small-diameter pinion 7b, which has a smaller diameter than the large-diameter pinion 7a. The large-diameter pinion 7a and the small-diameter pinion 7b are coaxial with each other and are arranged side by side in the direction of the rotation axis AL. The large-diameter pinion 7a and the small-diameter pinion 7b are formed as a single unit. Specifically, the large-diameter pinion 7a and the small-diameter pinion 7b are attached to the outer circumference of the pinion shaft 7c, which is the rotation axis of the stepped pinion 7. The large-diameter pinion 7a and the small-diameter pinion 7b and the pinion shaft 7c rotate as a single unit. The stepped pinion 7 constitutes the "planetary gear" of the "stepped pinion type planetary gear mechanism" that makes up the reduction gear mechanism 3. The large-diameter pinion 7a of the stepped pinion 7 meshes with the sun gear 5. The small-diameter pinion 7b of the stepped pinion 7 meshes with the ring gear 6. In the reduction gear mechanism 3, at least two stepped pinions 7 are arranged at equal intervals in the circumferential direction of the sun gear 5 and the ring gear 6. In the embodiment shown in Figure 2, three stepped pinions 7 are arranged at equal intervals in the circumferential direction of the sun gear 5 and the ring gear 6. These multiple stepped pinions 7 are supported and held by a carrier 8, which will be described later.

[0020] The carrier 8 is positioned coaxially with the sun gear 5 and ring gear 6, and is rotatable relative to the sun gear 5 and ring gear 6. The carrier 8 supports the multiple stepped pinions 7 so that they can rotate and revolve. Specifically, the carrier 8 rotatably supports the pinion shafts 7c of the stepped pinions 7. In the embodiment shown in Figure 1, the carrier 8 rotatably supports the pinion shafts 7c of the stepped pinions 7 via a bearing 11 provided between the carrier 8 and the pinion shafts 7c of the stepped pinions 7. The bearing 11 is supplied with oil 2, which has been used to lubricate the differential gear mechanism 4, as will be described later. The carrier 8 is connected to the differential case 12 of the differential gear mechanism 4, which will be described later, and transmits the torque of the carrier 8 to the differential case 12 and differential pinion shaft 16 of the differential gear mechanism 4. Therefore, the carrier 8 is the "output shaft" of the reduction gear mechanism 3.

[0021] As described above, the reduction gear mechanism 3 is constituted by the sun gear 5, the ring gear 6, the stepped pinion 7, and the carrier 8. Since the ring gear 6 is fixed so as not to rotate, in the reduction gear mechanism 3, that is, the "stepped pinion type planetary gear mechanism", when torque is transmitted to the sun gear 5 and the sun gear 5 rotates, the rotational speed of the carrier 8 decreases with respect to the rotational speed of the sun gear 5. Therefore, the "stepped pinion type planetary gear mechanism" functions as a "reduction mechanism" having the sun gear 5 as the "input shaft" and the carrier 8 as the "output shaft".

[0022] The differential gear mechanism 4 is housed inside the differential case 12 described later, is coaxial with the reduction gear mechanism 3, and is disposed on the inner peripheral side of the revolution orbit of the stepped pinion 7. Specifically, the differential gear mechanism 4 and the differential case 12 are disposed on the inner peripheral side (lower side in FIG. 1) of the small-diameter pinion 7b of the stepped pinion 7 in the radial direction (vertical direction in FIG. 1) of the reduction gear mechanism 3. In the embodiment shown in FIG. 1, the differential gear mechanism 4, together with the differential case 12, constitutes a "differential device" that distributes and transmits torque to the left and right drive wheels (not shown) of a vehicle (not shown). That is, the differential gear mechanism 4 has the same configuration as a so-called "differential gear" that has been generally used in the past, and has a differential case 12, a first side gear 13, a second side gear 14, a differential pinion 15, and a differential pinion shaft 16.

[0023] The differential case 12 is a housing-like member that covers the "differential gear", that is, the differential gear mechanism 4, and serves as an input member of the "differential gear". The carrier 8 of the reduction gear mechanism 3 described above is connected to the differential case 12. The differential case 12 and the carrier 8 rotate integrally.

[0024] The first side gear 13 is a large-diameter bevel gear and is attached to the rear end (right end in Figure 1) of the first rotating shaft 17. The first side gear 13 and the first rotating shaft 17 rotate together. In the embodiment shown in Figure 1, the first rotating shaft 17 is the "drive shaft" on the left side of the vehicle, and the left drive wheel (not shown) of the vehicle is attached to the tip of the first rotating shaft 17 (left end in Figure 1). Similarly, the second side gear 14 is a large-diameter bevel gear and is attached to the rear end (left end in Figure 1) of the second rotating shaft 18. The second side gear 14 and the second rotating shaft 18 rotate together. In the embodiment shown in Figure 1, the second rotating shaft 18 is the "drive shaft" on the right side of the vehicle, and the right drive wheel (not shown) of the vehicle is attached to the tip of the second rotating shaft 18 (right end in Figure 1).

[0025] The differential pinion 15 is a small-diameter bevel gear, smaller in diameter than the first side gear 13 and the second side gear 14, and is rotatably supported on the differential pinion shaft 16. The differential pinion 15 meshes with both the first side gear 13 and the second side gear 14. In the embodiment shown in Figure 2, three differential pinions 15 are provided.

[0026] The differential pinion shaft 16 supports the differential pinions 15 so that they can rotate relative to each other, as described above. The differential pinion shaft 16 is fitted into a through hole 19 formed in the differential case 12, and its axial direction is positioned perpendicular to the rotation axis AL of the first rotation axis 17 and the second rotation axis 18. The through hole 19 penetrates from the inner circumference 4a of the differential gear mechanism 4, where the side gears 13, 14 and the differential pinion 15 are arranged and oil 2 is supplied, to the outer circumference 4b of the differential gear mechanism 4. The through hole 19 is formed so that oil 2 can flow from the inner circumference 4a to the outer circumference 4b of the differential gear mechanism 4. The end of the differential pinion shaft 16 is fixed to the differential case 12, for example, by a pin member 20. As a result, the differential pinion 15 rotates on its own axis around the differential pinion shaft 16 while meshing with the first side gear 13 and the second side gear 14, and revolves together with the differential pinion shaft 16 and the differential case 12 around the rotation axis AL of the first rotation axis 17 and the second rotation axis 18.

[0027] When a drive torque is input to the differential case 12 from a predetermined drive source via the reduction gear mechanism 3, the drive torque is transmitted to the differential pinion 15 via the differential pinion shaft 16. At this time, if both the first rotating shaft 17 and the second rotating shaft 18 rotate at a constant speed in the same direction, the differential pinion 15 does not rotate on its own axis, but revolves around the first side gear 13 and the second side gear 14, meshing with the first side gear 13 and the second side gear 14. Therefore, the drive torque is distributed equally between the first side gear 13 and the second side gear 14. In other words, the drive torque is distributed equally between the first rotating shaft 17 and the second rotating shaft 18. On the other hand, when the first rotating shaft 17 and the second rotating shaft 18 rotate differentially, the differential pinion 15 rotates on its own axis while revolving around the first side gear 13 and the second side gear 14, meshing with the first side gear 13 and the second side gear 14. Therefore, the driving torque is distributed to the first side gear 13 and the second side gear 14 with a torque distribution (distribution ratio) corresponding to the rotational state of the first rotating shaft 17 and the second rotating shaft 18. In other words, the driving torque is distributed to the first rotating shaft 17 and the second rotating shaft 18 with a predetermined torque distribution (distribution ratio). Thus, the differential gear mechanism 4 distributes and transmits the driving torque output by the driving force source and input to the differential case 12 to the first rotating shaft 17 and the second rotating shaft 18, and also enables differential rotation between the first rotating shaft 17 and the second rotating shaft 18.

[0028] As described above, the differential gear mechanism 4 is a transmission device that transmits, for example, the driving torque of a vehicle, and is operated under heavy loads. Therefore, oil 2 is supplied to the differential gear mechanism 4 for lubrication and cooling. In the embodiment shown in Figure 1, an oil passage 21 is formed in the axial center portion of the first rotating shaft 17, opening at the rear end of the first rotating shaft 17. In addition, an oil passage (not shown) is formed in the first rotating shaft 17 that penetrates radially from the oil passage 21 to the outer circumferential surface of the first rotating shaft 17. Oil 2 discharged from, for example, an oil pump (not shown) is supplied to the differential gear mechanism 4 from the radial oil passage of the first rotating shaft 17 through the oil passage 21, lubricating the meshing portions of the first side gear 13 and the second side gear 14 and the differential pinion 15, as well as the differential pinion shaft 16. Alternatively, the configuration may involve supplying the differential gear mechanism 4 with oil 2 flowing into the oil passage 21 of the first rotating shaft 17 from another lubricated part (not shown) through the oil passage 21. Therefore, in the embodiment shown in Figure 1, the oil passage 21 of the first rotating shaft 17 as described above corresponds to the "oil supply section" in this embodiment of the invention.

[0029] Furthermore, as described above, the differential case 12 and the differential gear mechanism 4 are "rotating members" that rotate around the first rotation axis 17 and the second rotation axis 18, that is, around the rotation axis AL. In this embodiment of the invention, the differential case 12 does not have so-called "weight-reducing holes" or "stolen holes" that are commonly used in conventional configurations, and is configured to hold a certain amount of oil 2 inside the differential case 12.

[0030] Therefore, in the lubrication structure 1 of this embodiment of the invention, the oil 2 supplied to the differential case 12 from the "oil supply unit" is temporarily held inside the differential case 12. The oil 2 held inside the differential case 12 lubricates each component of the differential gear mechanism 4 arranged inside the differential case 12, and also flows toward the peripheral portion on the outer circumference of the differential case 12, i.e., the outer circumference portion 12a, due to the centrifugal force when the differential case 12 rotates.

[0031] Furthermore, the lubrication structure 1 in this embodiment of the invention is configured to supply the oil 2 that has moved to the outer peripheral portion 12a when the differential case 12 rotates, mainly to the stepped pinion 7 of the "stepped pinion type planetary gear mechanism" that constitutes the reduction gear mechanism 3, as described above.

[0032] Specifically, in this embodiment of the invention, the differential case 12 has lubrication oil passages 22 and 23 formed on the outer peripheral portion 12a of the differential case 12, at positions corresponding to the large-diameter pinion 7a and the small-diameter pinion 7b of the stepped pinion 7 in the direction of the rotation axis AL, respectively, passing between the inner surface 12b of the differential case 12 and the outer surface 12c of the differential case 12.

[0033] The lubrication oil passage 22 is formed in the outer peripheral portion 12a of the differential case 12 at a position corresponding to the large-diameter pinion 7a of the stepped pinion 7 in the direction of the rotation axis AL, penetrating the outer shell portion 12d of the differential case 12 in the direction of the rotation axis AL. On the other hand, the lubrication oil passage 23 is formed in the outer peripheral portion 12a of the differential case 12 at a position corresponding to the small-diameter pinion 7b of the stepped pinion 7 in the direction of the rotation axis AL, penetrating the outer shell portion 12d of the differential case 12 in the radial direction (up and down direction in Figure 1). Therefore, the oil 2 supplied to the differential case 12 lubricates the differential gear mechanism 4, and then efficiently supplies the teeth 7d of the large-diameter pinion 7a and the teeth 7e of the small-diameter pinion 7b of the stepped pinion 7 by passing through the lubrication oil passages 22 and 23.

[0034] As described above, the lubrication oil passages 22 and 23 formed in the outer peripheral portion 12a of the differential case 12 are both formed at predetermined locations in the circumferential direction of the outer shell portion 12d of the differential case 12. Furthermore, the lubrication oil passages 22 and 23 may each be formed at multiple equally spaced locations in the circumferential direction of the outer shell portion 12d of the differential case 12. For example, the lubrication oil passages 22 and 23 may each be formed at four locations at 90° intervals in the circumferential direction of the outer shell portion 12d. In the embodiment shown in Figure 2, the lubrication oil passages 22 and 23 are each formed at three locations at 120° intervals in the circumferential direction of the outer shell portion 12d.

[0035] As described above, the differential case 12 in this embodiment of the invention is configured to hold oil 2 within the differential case 12. To this end, the differential case 12 is configured such that, for example, if the flow rate of oil 2 supplied to the differential case 12 is defined as the inflow flow rate and the flow rate of oil 2 flowing out from the lubrication oil passages 22 and 23 is defined as the outflow flow rate, the outflow flow rate is less than the inflow flow rate. Specifically, if the flow rate of oil 2 flowing out from parts of the differential case 12 other than the lubrication oil passages 22 and 23 is defined as the leakage flow rate, the differential case 12 is configured such that the sum of the above-mentioned outflow flow rate and leakage flow rate is approximately equal to the inflow flow rate.

[0036] Furthermore, in this embodiment of the invention, in order to retain the oil 2 inside the differential case 12 as described above, the differential case 12 may be provided with a "sealing member" to suppress the outflow of oil 2 in areas where the oil 2 supplied to the differential case 12 may flow out to places other than the lubrication oil passages 22 and 23. In the embodiment shown in Figure 1, an oil seal 24 is provided in the rotating sliding part between the differential case 12 and the first side gear 13. Also, an oil seal 25 is provided in the rotating sliding part between the differential case 12 and the second side gear 14.

[0037] The lubrication passages 22 and 23 are provided in consideration of the balance between the inflow and outflow rates of oil 2 to the differential case 12, as well as the effect of "sealing members" such as oil seals 24 and 25, i.e., the leakage rate of oil 2 from the differential case 12. In short, in this embodiment of the invention, the shape and size of the lubrication passages 22 and 23, as well as the arrangement position and number of the lubrication passages 22 and 23, are determined so that the amount of oil 2 supplied to the differential case 12 is balanced with the amount of oil 2 discharged from the differential case 12 to the stepped pinion 7 of the reduction gear mechanism 3.

[0038] Therefore, according to the lubrication structure 1 in this embodiment of the invention, a simple configuration is achieved by simply adding lubrication oil passages 22 and 23 to the outer peripheral portion 12a of the differential case 12, enabling efficient and more appropriate supply of lubricating oil 2 to a gear system consisting of a reduction gear mechanism 3 using a stepped pinion type planetary gear mechanism and a differential gear mechanism 4. [Explanation of symbols]

[0039] 1 Lubrication structure 2 oils 3. Reduction gear mechanism (stepped pinion type planetary gear mechanism) 4. Differential gear mechanism 4a Inner circumference (of the differential gear mechanism) 4b (outer part of differential gear mechanism) 5. Sun gear (of a differential gear mechanism) 6. Ring gear (of a differential gear mechanism) 7. Stepped pinion (of a differential gear mechanism) 7a Large diameter pinion (for stepped pinions) 7b Small diameter pinion (for stepped pinions) 7c (Pinion shaft of a stepped pinion) 7d (Tooth portion of large diameter pinion) 7e (Teeth of a small diameter pinion) 8. Carrier (of the differential gear mechanism) 9. Sun gear shaft (of differential gear mechanism) 10 cases 11 bearings 12 Differential Case 12a (Differential case) outer circumference 12b (Inner surface of differential case) 12c (exterior of differential case) 12d (Differential case) outer shell 13 First side gear 14. Second side gear 15 Differential pinion 16 Differential pinion shaft 17. First rotation axis (drive shaft) 18. Second rotation axis (drive shaft) 19 Through holes 20 Pin component 21 Oil passage (oil supply section) 22 Lubricating oil path 23 Lubricating oil path 24 Oil seal (sealing component) 25 Oil seal (sealing component) AL rotation axis

Claims

[Claim 1] A gear system lubrication structure comprising: a reduction gear mechanism composed of an external sun gear, an internal ring gear, a stepped pinion integrally formed with a large-diameter pinion that meshes with the sun gear and a small-diameter pinion smaller in diameter than the large-diameter pinion that meshes with the ring gear, and a planetary gear mechanism having a carrier that supports the stepped pinion so that it can rotate and revolve; a differential case arranged coaxially with the reduction gear mechanism on the inner circumference side of the orbital path of the stepped pinion, holding lubricating oil supplied from a predetermined oil supply unit and rotating when torque is transmitted from the reduction gear mechanism; and a differential gear mechanism arranged inside the differential case, distributing and transmitting the torque input to the differential case to two coaxially arranged, relatively rotatable rotating members, and enabling differential rotation of the two rotating members, wherein when the differential case rotates, the oil supplied to the differential case to lubricate the differential gear mechanism is supplied to the reduction gear mechanism to lubricate the reduction gear mechanism. The differential case has lubrication passages formed on its outer circumference, corresponding to the large-diameter pinion and the small-diameter pinion in the direction of the rotation axis, respectively, penetrating between the inner and outer surfaces of the differential case. A lubrication structure for a gear mechanism characterized by the following features.

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