Lubrication structure of gear mechanism

Abstract

To provide a lubrication structure of a gear mechanism capable of quickly supplying lubricant to a meshing surface or the like even when operation starts.SOLUTION: A lubrication structure 1 of a gear mechanism 2 comprises a gear 5 having a hollow portion penetrating in an axial direction, and a shaft 8 inserted into the hollow portion of the gear and having an oil path 11 formed therein for supplying oil to the gear 5. The oil path 11 has a first oil path 12 formed so as to extend in the axial direction of the shaft 8 and having one open end part in the axial direction, a second oil path 13 formed so as to extend in a radial direction from the other closed end part of the first oil path 12 and opening onto an outer peripheral surface of the shaft 8, and an oil holding part 14 formed so as to extend in the radial direction opposite the second oil path 13 across the first oil path 12 and having a closed end part opposite the opening end to the first oil path 12.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a structure for supplying lubricating oil to the meshing surfaces of a gear mechanism and the like.

Background Art

[0002] Patent Document 1 discloses a lubrication structure of a driving force transmission device configured to adjust the amount of lubricating oil supplied to a planetary gear and an engagement element according to a change in the rotational speed. In the structure of Patent Document 1, an oil catch plate is attached to one side in the axial direction of a carrier constituting a planetary gear. The oil catch plate supplies the lubricating oil supplied from the axial oil passage of the input shaft to the meshing surface of the planetary gear and the friction engagement elements arranged on the outer peripheral side of the planetary gear. The oil catch plate is formed with a radially extending passage configured to supply lubricating oil to the friction engagement elements. An on-off valve that opens and closes according to the rotational speed of the oil catch plate is provided in the passage. The on-off valve is configured such that when the rotational speed of the oil catch plate exceeds a predetermined rotational speed set in advance, the valve body of the on-off valve moves radially outward to open the passage. Thereby, when the rotational speed of the oil catch plate increases, the on-off valve is opened, so that the amount of lubricating oil supplied to the friction engagement elements through the passage can be increased.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] On the one hand, in a structure such as that of Patent Document 1, when the supply of lubricating oil to the axial oil passage is stopped and the rotation of the input shaft stops, the lubricating oil is discharged to the outside of the drive force transmission device from the gaps between components, the oil passage, etc. due to gravity or the like. That is, the lubricating oil is discharged from the through hole (oil passage) formed in the pinion shaft and the axial oil passage. Therefore, when the operation of the planetary gear is restarted, the supply of lubricating oil to the meshing surfaces of the gears may be delayed. Even if the supply of lubricating oil is started by an oil pump or the like before the start of the operation of the planetary gear, if the planetary gear is not operating, the lubricating oil cannot reach the through hole of the pinion shaft described above, and there may be a shortage of lubricating oil on the meshing surfaces of the gears.

[0005] The present invention has been made paying attention to the above technical problems, and an object thereof is to provide a lubrication structure for a gear mechanism capable of quickly supplying lubricating oil to meshing surfaces and the like even at the start of operation.

Means for Solving the Problems

[0006] In order to achieve the above object, the present invention provides a lubrication structure for a gear mechanism including a gear having a hollow portion penetrating in the axial direction, and a shaft inserted into the hollow portion of the gear and having an oil passage formed therein for supplying oil to the gear. The oil passage includes a first oil passage formed to extend in the axial direction of the shaft and having one end opened in the axial direction, a second oil passage formed to extend radially from the closed other end side of the first oil passage and opened on the outer peripheral surface of the shaft, and an oil holding portion formed to extend radially on the opposite side of the first oil passage with the first oil passage interposed therebetween and having an end opposite to the open end to the first oil passage closed.

Effects of the Invention

[0007] According to the lubrication structure of the gear mechanism of the present invention, when the gear mechanism is operating, oil can be supplied to the meshing surfaces of the gears and the like through the first oil passage and the second oil passage formed in the shaft. Further, when the gear mechanism is stopped and the oil holding portion extends downward from the first oil passage, the oil remaining in the first oil passage and the like is stored in the oil holding portion. Therefore, when the stopped gear mechanism starts to operate, the oil held in the oil holding portion is immediately supplied to the meshing surfaces of the gears and the like. Accordingly, even if the supply of the oil discharged from the oil pump or the like is delayed when the gear mechanism restarts, it is possible to suppress a shortage of oil on the meshing surfaces of the planetary gear mechanism and the like. Further, the oil holding portion extends in a direction opposite to the second oil passage in the radial direction with the first oil passage interposed therebetween, and can be formed only by extending the second oil passage, so that the oil holding portion can be easily formed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] Hereinafter, the present invention will be described based on the embodiments shown in the drawings. It should be noted that the embodiments described below are merely examples when the present invention is embodied, and do not limit the present invention.

[0010] FIG. 1 shows an example of the lubrication structure 1 in an embodiment of the present invention. The lubrication structure 1 shown in FIG. 1 is applied to a planetary gear mechanism 2 corresponding to the gear mechanism in the embodiment of the present invention. The planetary gear mechanism 2 is a gear mechanism that generates a differential action by three rotating elements, similar to a conventionally known planetary gear mechanism. The planetary gear mechanism 2 shown in FIG. 1 is a so-called single pinion type planetary gear mechanism 2.

[0011] The planetary gear mechanism 2 includes, as three rotating elements, a sun gear 3, a ring gear 4 which is an internal gear provided concentrically with respect to the sun gear 3, and a carrier 6 which is disposed between the sun gear 3 and the ring gear 4 and holds a plurality of pinion gears 5 (planetary gears) that mesh with the sun gear 3 and the ring gear 4 so as to be rotatable and revolvable. The plurality of pinion gears 5 are arranged at equal intervals in the rotational direction. As an example, in the planetary gear mechanism 2 shown in FIG. 1, the sun gear 3 is integrated with the input shaft 7 to become an input element, the ring gear 4 is connected to a case 8 or the like to become a fixed element, and the carrier 6 is connected to an output member (not shown) or the like to become an output element. In FIG. 1, for convenience of explanation, only one of the plurality of pinion gears 5 is shown.

[0012] Also, as shown in FIG. 1, the carrier 6 holds a plurality of pinion gears 5 by connecting pinion pins 9 inserted into a hollow portion penetrating in the axial direction of the pinion gear 5. Specifically, as shown in FIG. 1, pinion pins 9 that are longer than the pinion gear 5 in the axial direction are inserted inside the pinion gear 5 respectively. The pinion pins 9 slightly protrude from both ends in the axial direction of the pinion gear 5. The carrier 6 is disposed on both sides in the rotational axis direction of the pinion gear 5 and is connected to the protruding portions of the pinion pins 9. By connecting the carrier 6 and the plurality of pinion pins 9 in this way, the plurality of pinion pins 9 are connected to each other, and the plurality of pinion gears 5 can revolve by an angle corresponding to the rotation angle of the carrier 6 while being arranged at equal intervals in the rotational direction. Also, as shown in FIG. 1, a bearing 10 such as a needle bearing is provided between the pinion pin 9 and the pinion gear 5. Therefore, relative rotation between the pinion gear 5 and the pinion pin 9 is possible, and the pinion gear 5 can rotate. Note that the pinion gear 5 corresponds to the gear in the embodiment of the present invention, and the pinion pin 9 corresponds to the shaft in the embodiment of the present invention.

[0013] In the planetary gear mechanism 2 configured as described above, a lubrication structure 1 for supplying oil for lubrication and cooling is formed on the meshing surfaces between the gears of the sun gear 3, the pinion gear 5, and the ring gear 4. For example, oil sucked up by an electric oil pump (not shown) is supplied to a hollow portion (not shown) formed inside the input shaft 7, and the oil is supplied to the planetary gear mechanism 2 through an oil passage 11 formed inside the pinion pin 9.

[0014] The oil passage 11 formed in the pinion pin 9 extends in the axial direction of the pinion pin 9, has a first oil passage 12 with one end opening axially and the other end extending to near the center in the axial direction of the pinion pin 9. The first oil passage 12 is formed along the central axis of the pinion pin 9. One end of the first oil passage 12 is formed in a tapered shape such that the diameter increases toward the opening portion. Further, the oil passage 11 has a second oil passage 13 formed to extend in the radial direction of the pinion pin 9, with one end communicating with the other end of the first oil passage 12. The other end of the second oil passage 13 opens to the outer peripheral surface of the pinion pin 8. The second oil passage 13 with the other end opening is formed in the pinion pin 9 at a position farther from the rotation center of the carrier 6 than the first oil passage 12, that is, located radially outside the first oil passage 12. Furthermore, an oil holding portion 14 with one end communicating with the other end of the first oil passage 12 is formed in the oil passage 11.

[0015] The oil holding portion 14 extends in a direction radially opposite to the second oil passage 13 from the first oil passage. That is, as shown in FIG. 2, the oil holding portion 12 is formed to face each other with the second oil passage 13 and the first oil passage 12 interposed therebetween. As shown in FIGS. 1 and 2, the oil holding portion 14 opens to the first oil passage 12, and the end opposite to the opening end to the first oil passage 12 is closed. Therefore, it is possible to store oil inside the oil holding portion 14. Also, the oil holding portion 14 is formed inside the pinion pin 9 at a position closer to the rotation center of the carrier 6 than the first oil passage 12 in the radial direction, that is, located radially inside the first oil passage 12.

[0016] When the plurality of pinion pins 9 configured as such are at the stop angle of 0° of the pinion pin 9, that is, when the direction of the first oil passage 12 in the pinion pin 9 overlaps with the direction perpendicular to the rotation center axis of the carrier 6, as shown in Fig. 2(a), the other end of the second oil passage 13 is arranged to open upward along the vertical direction. In other words, when the pinion pin 9 is at the highest position in the vertical direction, the second oil passage 13 and the oil holding portion 14 extend along the vertical direction, and the pinion pin 9 is arranged such that the other end side of the oil holding portion 14, that is, the closed side, is located on the lower side in the vertical direction.

[0017] For example, in the case of the planetary gear mechanism 2 having three pinion gears 5, as shown in Fig. 2(a), when the stop angle of the pinion pin 9 is 0°, the closed side of the oil holding portion 14 of one pinion pin 9 at the highest position in the vertical direction is located on the lower side in the vertical direction. On the other hand, since the plurality of pinion pins 9 are arranged at equal intervals in the rotation direction, the oil holding portions 14 formed in the other two pinion pins 9 are at positions higher than the side where the side opening to the first oil passage 12 is closed in the vertical direction. Therefore, although it is highly likely that oil is not held in the oil holding portions 14 formed in the other two pinion pins 9, oil is held in the oil holding portion 14 of the pinion pin 9 at the highest position in the vertical direction.

[0018] Further, regardless of the stop position of the pinion pin 9, which is not the position shown in Fig. 2(a), the pinion pin 9 will be located at a position higher than the rotational center axis of the carrier 6. For example, as shown in Fig. 2(b), even when the pinion pin 9 has rotated 100° clockwise from the position shown in Fig. 2(a) in response to the rotation of the carrier 6, the pinion pin 9 is located at a position higher than the rotational center axis of the carrier 6. Since the pinion pin 9 does not rotate on its own and rotates around the center of the three pinion pins 9, when the central axis of the pinion pin 9, that is, the first oil passage 12, is at a position higher than the rotational center axis of the carrier 6, the closed side of the oil holding portion 14 will be at a position lower than the second oil passage 13. And since the three pinion pins 9 are arranged at equal intervals in the rotational direction, regardless of the rotation angle of the carrier 6, oil will always be stored in the oil holding portion 14 of the pinion pin 9 that is at the highest position in the vertical direction.

[0019] The planetary gear mechanism 2 configured in this way operates under a large load when, for example, torque for vehicle running is transmitted. Therefore, oil for lubrication and cooling is supplied to the planetary gear mechanism 2 as described above. Specifically, during the operation of the planetary gear mechanism 2, that is, when the planetary gear mechanism 2 is transmitting torque or power, the oil supplied to the hollow portion of the input shaft 7 from an oil pump or the like is supplied to the first oil passage 12 formed inside the pinion pin 9 by the centrifugal force associated with the rotation of the sun gear 3. Then, the oil that has entered the first oil passage 12 is discharged from the second oil passage 13 due to the rotation or revolution of the pinion gear 5. Thereby, oil can be supplied to the meshing portions of the sun gear 3, pinion gear 5, and ring gear 4 that constitute the planetary gear mechanism 2, as well as to the carrier 6, bearing 10, etc., to lubricate and cool them.

[0020] On the contrary, when the operation of the planetary gear mechanism 2 stops, there is no need for lubrication or cooling. Therefore, the oil pump is stopped to suppress power consumption and reduce the amount of lubricating oil used. In the planetary gear mechanism 2, as the rotational speed of each gear decreases, the centrifugal force acting on the planetary gear mechanism 2 and each gear decreases, and oil does not reach each meshing surface. When the operation of the planetary gear mechanism 2 stops in this way, the oil remaining in the hollow portion of the input shaft 7 and the oil passage 11 of the pinion pin 9 gradually drains to the outside through the portions communicating with the outside of the hollow portion and the oil passage 11 by gravity, for example, from the first oil passage 12 and the second oil passage 13. As a result, when the planetary gear mechanism 2 in the stopped state starts, it takes time for the oil discharged from the oil pump to be supplied to the hollow portion and for the oil to reach the oil passage 11 from the hollow portion.

[0021] On the other hand, according to the lubrication structure 1 in the embodiment of the present invention, oil is stored in the oil holding portion 14 formed inside the pinion pin 9. That is, even if the planetary gear mechanism 2 is in a stopped state, the oil is held in the oil passage 11 inside the pinion pin 9. Therefore, when the planetary gear mechanism 2 starts to restart as described above, even if the supply of the oil discharged from the oil pump is delayed, a centrifugal force sufficient to scatter the oil acts on the pinion pin 9, and immediately the oil in the oil holding portion 14 is supplied to each meshing surface of the planetary gear mechanism 2. Further, since the oil holding portion 14 is formed at a position facing the second oil passage 13 in the radial direction, the oil discharged from the oil holding portion 14 is easily supplied to the second oil passage 13. Therefore, when the planetary gear mechanism 2 restarts, it is possible to suppress a shortage of oil on each meshing surface of the planetary gear mechanism 2 until the oil discharged from the oil pump is supplied to the oil passage 11, and thus prevent or suppress a situation such as seizure. Furthermore, the oil holding portion 14 extends on the opposite side in the radial direction of the second oil passage 13 with the first oil passage 12 interposed therebetween, and can be formed only by extending the second oil passage, so that the oil holding portion can be easily formed.

[0022] In the lubrication structure 1 described above, the configuration in which one oil holding portion 14 is formed on the pinion pin 9 has been described. However, the oil holding portion 14 may be formed in plurality on each pinion pin 9 according to the amount of oil required at the start of the planetary gear mechanism 2 or the like. An example of the lubrication structure 21 in such another embodiment is shown in FIG. 3. As shown in FIG. 3, in the oil passage 22 of the lubrication structure 21 in another embodiment, three second oil passages 24 and three oil holding portions 25 are formed on one pinion pin 23. The second oil passages 24 formed on the pinion pin 23 in the other lubrication structure 21 are formed at equal intervals at positions shifted by 120° in the rotational direction of the carrier 6. Therefore, the amount of oil supplied to each meshing surface and the bearing 10 or the like in the planetary gear mechanism 2 can be increased.

[0023] Also, the oil holding portions 25 formed on the pinion pin 23 in the other lubrication structure 21 are formed at positions shifted by 120° in the rotational direction, similar to the second oil passages 24. Further, the oil holding portion 25 and the second oil passage 24 are formed at positions shifted by 60° in the rotational direction of the carrier 6 with respect to each other. That is, the second oil passage 24 and the oil holding portion 25 are alternately formed in the rotational direction of the carrier 6.

[0024] In the lubrication structure 21 in such another embodiment configured as described above, the amount of oil held in the oil passage 22 of the pinion pin 23 can be further increased as compared with the lubrication structure 21 described above. As an example, a case where three pinion pins 23 are provided, similar to the embodiment shown in FIG. 2, will be described. As shown in FIG. 3(a), when the stop angle of the pinion pin 23 is 0°, that is, when the closed side of one oil holding portion 25 in the pinion pin 23 is at the highest position in the vertical direction, in any of the pinion pins 23, two oil holding portions 25 are in a state where they can store oil. That is, at least one of the three oil holding portions 25 formed on the pinion pin 23 is located at a position lower than the rotational axis of the carrier 6 in the vertical direction.

[0025] Also, as shown in FIG. 3(b), even when the pinion pin 23 has rotated 100° clockwise from the position shown in FIG. 3(a) in response to the rotation of the carrier 6, there are a plurality of oil holding portions 25 on all the pinion pins 23 where the closed side faces downward in the vertical direction from the open side. That is, regardless of the rotation angle of the carrier 6, oil will be held in at least one oil holding portion 25 in any of the pinion pins 23. Therefore, even in the lubrication structure 21 in other embodiments, the same effects as those described above can be obtained. Further, in the lubrication structure 21 in other embodiments, since oil is always held in the oil passages 22 of each pinion pin 23, it is possible to further suppress the shortage of oil. Also, even immediately after the restart of the planetary gear mechanism 2, the oil can be spread over a wider range, that is, the entire planetary gear mechanism 2 can be made to be in a better lubricated state.

Description of Reference Numerals

[0026] 1, 21 Lubrication structure 2 Planetary gear mechanism (gear mechanism) 5 Pinion gear (gear) 9, 23 Pinion pin (shaft) 11, 22 Oil passage 12 First oil passage 13, 24 Second oil passage 14, 25 Oil holding portion

Claims

[Claim 1] a gear having a hollow portion passing through in an axial direction; a shaft that is inserted into the hollow portion of the gear and has an oil passage formed therein for supplying oil to the gear, The oil passage is a first oil passage extending in an axial direction of the shaft and having an open end in the axial direction; a second oil passage extending radially from the other end side of the first oil passage, the other end side being closed, and opening onto an outer circumferential surface of the shaft; The second oil passage is formed to extend radially opposite to the first oil passage, and has an oil retaining portion whose end opposite to an open end to the first oil passage is closed. A lubrication structure for a gear mechanism.

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