Power transmission

Abstract

To provide a power transmission device in which a case housing a stepped pinion type planetary gear mechanism and a strainer can be reduced in the size in the vertical direction.SOLUTION: The power transmission device for a vehicle is provided, comprising: a planetary gear mechanism 2 constituted of a sun gear S, a first pinion gear P1 meshing with the sun gear S, a second pinion gear P2 rotated integrally with the first pinion gear P1 and formed smaller in diameter than the first pinion gear P1, a carrier holding the first pinion gear P1 and the second pinion gear P2 in a rotatable and revolvable manner, and a ring gear R meshing with the second pinion gear P2; a case 3 housing the planetary gear mechanism 2; and an oil pump pumping oil from a strainer 4 immersed in the oil filled in the case 3, wherein the strainer 4 is arranged in the direction that the oil is scraped up with the rotation of the first pinion gear P1 due to the travel of the vehicle.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power transmission device equipped with a planetary gear mechanism constituted by a plurality of rotating elements. [Background technology]

[0002] Patent Document 1 describes a power transmission device in which a stepped pinion type planetary gear mechanism is housed in a case, the stepped pinion type planetary gear mechanism being made up of a sun gear connected to a motor which is a driving force source, a large-diameter first pinion gear which meshes with the sun gear, a second pinion gear which rotates integrally with the first pinion gear and has a smaller diameter than the first pinion gear, a carrier which holds the first pinion gear and the second pinion gear so that they can rotate and revolve about their axes, and a ring gear which meshes with the second pinion gear. An oil pan for storing oil is attached to the lower end of the case in the vertical direction, and a strainer which communicates with an oil pump is immersed in the oil in the oil pan. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-174584 A Summary of the Invention [Problem to be solved by the invention]

[0004] The power transmission device described in Patent Document 1 is configured to reduce the rotation of the motor and output it by using a stepped pinion type planetary gear mechanism. Therefore, the function of the reducer can be achieved with a single shaft, so that the size in the radial direction can be suppressed. In contrast, the stepped pinion type planetary gear mechanism is arranged in the center of the width direction (i.e., horizontal direction) of the case because each rotating element rotates and revolves around a predetermined rotation axis. Therefore, even when the vehicle runs uphill or downhill or turns, the strainer must be immersed in the oil in the case, so the strainer is usually arranged in the center of the width direction of the case. Therefore, in a power transmission device using a stepped pinion type planetary gear mechanism, the strainer is arranged below the stepped pinion type planetary gear mechanism in the vertical direction, and the power transmission device may become larger in the vertical direction.

[0005] The present invention has been made in light of the above technical problems, and has an object to provide a power transmission device in which the case housing the stepped pinion type planetary gear mechanism and the strainer can be made smaller in the vertical direction. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a power transmission device for a vehicle, comprising a stepped pinion type planetary gear mechanism including a sun gear, a first pinion gear meshing with the sun gear, a second pinion gear rotating integrally with the first pinion gear and formed with a smaller diameter than the first pinion gear, a carrier holding the first pinion gear and the second pinion gear so that they can rotate and revolve about their axes, and a ring gear meshing with the second pinion gear, a case accommodating the stepped pinion type planetary gear mechanism, and an oil pump pumping up the oil from a strainer immersed in oil sealed in the case. The strainer is aligned horizontally with the stepped pinion type planetary gear mechanism at the same height as a lower end of the stepped pinion type planetary gear mechanism in a vertical direction, and is disposed in front of the stepped pinion type planetary gear mechanism. A direction in which the oil is scooped up by the rotation of the first pinion gear when the vehicle is running. Distributed to The present invention is characterized in that it is placed Effect of the Invention

[0007] According to this invention, when the vehicle runs, the first pinion gear in the stepped pinion planetary gear mechanism rotates and revolves, and the first pinion gear revolves and rotates, scooping up the oil, and a strainer is provided in the direction in which the scooped up oil splashes. Therefore, it is possible to pump up the oil with the oil pump without providing an oil pan for storing the oil at the bottom end of the case that houses the stepped pinion planetary gear mechanism, or a strainer below the stepped pinion planetary gear mechanism. As a result, the power transmission device can be made smaller in the vertical direction. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram for explaining an example of a power transmission device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A schematic diagram for explaining an example of a power transmission device according to an embodiment of the present invention is shown in Fig. 1. The power transmission device 1 shown in Fig. 1 includes a planetary gear mechanism 2 that functions as a reducer provided between a driving force source such as an engine or a motor (not shown) and a driving wheel. The planetary gear mechanism 2 is a stepped pinion type planetary gear mechanism including a sun gear S, a first pinion gear P1 that meshes with the sun gear S, a second pinion gear P2 that rotates integrally with the first pinion gear P1 and has a smaller diameter than the first pinion gear P1, a carrier (not shown) that holds the first pinion gear P1 and the second pinion gear P2 so that they can rotate and revolve around the rotational center axis of the sun gear S and is connected to an output shaft (not shown), and a ring gear R that is arranged concentrically with the sun gear S and meshes with the second pinion gear P2.

[0010] The above-mentioned first pinion gear P1 and second pinion gear P2 are each provided in threes at a predetermined interval in the revolution direction, and a portion of the first pinion gear P1 is configured to protrude outward beyond the outer circumferential edge of the ring gear R.

[0011] The ring gear R is fixed to a case 3 that houses the planetary gear mechanism 2 by bolts or the like (not shown).

[0012] In addition, when an engine is used as the driving force source, since the rotation direction of the engine is limited to one direction, a forward / reverse switching mechanism capable of selectively reversing the rotation direction may be provided on the output side of the planetary gear mechanism 2. Also, in order to obtain the reduction ratio required for the vehicle, another reducer (including a gear pair) may be provided on the output side of the planetary gear mechanism 2.

[0013] The case 3 is filled with oil for lubricating the planetary gear mechanism 2 and other gears and for cooling these members. The oil level is configured so that at least a portion of a given first pinion gear P1 is immersed in the oil while the first pinion gear P1 makes one rotation (revolution) around the central axis of rotation of the sun gear S. In other words, the first pinion gear P1 is immersed in the oil, and the oil is scooped up by the revolution and rotation of the first pinion gear P1.

[0014] 1 is configured such that oil sealed inside is pumped up by an oil pump (not shown) and supplied to the planetary gear mechanism 2 and other gears, and the strainer 4 provided at the end of the oil passage communicating with the oil pump is immersed in the oil. Specifically, as described above, the strainer 4 is provided in the direction in which the oil is scooped up and scattered by the first pinion gear P1. In other words, the strainer 4 is disposed at approximately the same height as the lower end of the planetary gear mechanism 2 in the vertical direction and aligned in the horizontal direction.

[0015] Furthermore, the power transmission device 1 shown in FIG. 1 is provided with a partition plate 5 for separating the lower portion of the case 3 into an area A (hereinafter referred to as the first area) where the planetary gear mechanism 2 is provided and an area B (hereinafter referred to as the second area) where the strainer 4 is provided.

[0016] This partition plate 5 is intended to prevent the oil, which has been scooped up by the first pinion gear P1 and scattered from the first area A to the second area B, from flowing back toward the first area A. In other words, it is intended to prevent the amount of oil in the second area B from decreasing. Therefore, in order to keep the strainer 4 immersed in the oil stored in the second area B, the height of the partition plate 5 is formed to a position higher than the upper end of the suction port of the strainer 4, as shown by the dashed line in FIG. 1.

[0017] Also, when the vehicle is traveling uphill, the oil level inclines relative to the bottom surface of the case 3. Similarly, when the vehicle is turning, the oil level inclines relative to the horizontal direction due to the centrifugal force acting on the oil. That is, the oil level from the bottom surface of the case 3 in the vertical direction at the position where the strainer 4 is provided may be lower than the oil level from the bottom surface of the case 3 in the vertical direction at the position where the partition plate 5 is provided. Therefore, in the example shown in FIG. 1, the height of the upper end of the partition plate 5 is configured to be higher than the height of the suction port of the strainer 4 in the vertical direction when the vehicle is tilted to the limit value of the vehicle's hill-climbing performance. In FIG. 1, the horizontal direction when the vehicle is tilted to the limit value of the hill-climbing performance is shown by a dashed line.

[0018] Furthermore, in order to smoothly scoop up the oil by the revolution and rotation of the first pinion gear P1, the partition plate 5 is formed in a shape that is offset with respect to the movement path of the outermost circumference of the first pinion gear P1 in the radial direction of the sun gear S. In other words, the partition plate 5 is formed in an arc shape centered on the central axis of rotation of the sun gear S.

[0019] As described above, the first pinion gear P1 revolves and rotates to scoop up the oil, and by providing the strainer 4 in the direction in which the scooped up oil splashes, it is possible to pump up the oil with the oil pump without providing an oil pan for storing the oil at the lower end of the case 3 or providing the strainer 4 below the planetary gear mechanism 2. As a result, the power transmission device 1 can be made smaller in the vertical direction.

[0020] Furthermore, by separating the first area A on the side where the planetary gear mechanism 2 is provided from the second area B on the side where the strainer 4 is provided by the partition plate 5, it is possible to prevent the oil that has splashed into the second area B from flowing back into the first area A. This makes it possible to prevent the oil level in the second area B from becoming lower. In particular, by forming the upper end of the partition plate 5 higher than the suction port of the strainer 4, it is possible to prevent the oil level in the second area B from becoming lower than the suction port of the strainer 4. As a result, it is possible to prevent the strainer 4 from sucking in air at the same time as it sucks in oil.

[0021] Furthermore, by forming the partition plate 5 so that the upper end of the partition plate 5 in the vertical direction when the vehicle is tilted to the limit value of the hill-climbing performance is higher than the suction port of the strainer 4, it is possible to prevent the oil level in the second region B from becoming lower than the suction port of the strainer 4 even when the vehicle is tilted. As a result, it is possible to prevent the strainer 4 from sucking in air at the same time as sucking in oil.

[0022] Furthermore, by forming the partition plate 5 in a shape that is offset with respect to the movement trajectory of the outermost part of the first pinion gear P1 in the radial direction of the sun gear S, it is possible to prevent excess oil from accumulating between the first pinion gear P1 and the partition plate 5, thereby reducing oil churning loss. [Explanation of symbols]

[0023] 1 Power transmission device 2 Planetary gear mechanism 3 Cases 4 Strainer 5 Partition A 1st area B 2nd area P1,P2 pinion gear R ring gear S Sun gear

Claims

[Claim 1] A power transmission device for a vehicle, comprising: a stepped pinion type planetary gear mechanism including a sun gear, a first pinion gear meshing with the sun gear, a second pinion gear rotating integrally with the first pinion gear and formed with a smaller diameter than the first pinion gear, a carrier holding the first pinion gear and the second pinion gear so that they can rotate and revolve about their axes, and a ring gear meshing with the second pinion gear; a case accommodating the stepped pinion type planetary gear mechanism; and an oil pump pumping up the oil from a strainer immersed in oil sealed in the case, The strainer is aligned horizontally with the stepped pinion type planetary gear mechanism at the same height as a lower end of the stepped pinion type planetary gear mechanism in the vertical direction, and is disposed in a direction in which the oil is scooped up by the rotation of the first pinion gear caused by the running of the vehicle. A power transmission device for a vehicle.

Images