Power transmission device

Abstract

To ensure sufficient lubrication for the pinion shaft while suppressing an increase in the number of parts, thereby reducing leakage. [Solution] A power transmission device comprising a planetary gear mechanism having a sun gear, a pinion gear, a ring gear and a carrier supporting the pinion gear, and a rotating member arranged along the rotational centerline of the planetary gear mechanism and rotating integrally with the sun gear, wherein lubricating oil can be supplied to the bearing portion of the pinion gear, and a lubrication groove is formed on the end face of the planetary gear mechanism to guide lubricating oil to the tooth surface of the planetary gear mechanism.

Description

[[Technical Field]]

[0001] The present disclosure relates to a power transmission device. [[Background Art]]

[0002] Patent Document 1 discloses that providing an oil receiver and adopting a fixed two-plate structure provides a lubricating oil guide hole for guiding lubricating oil to an opening, which can reliably supply lubricating oil to a pinion shaft and improve lubrication performance. [[Prior Art Documents]] [[Patent Documents]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Application Publication No. 2015-206454 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] However, the above-described prior art has a problem that it is necessary to increase the number of components in order to reduce leakage amount.

[0005] The present disclosure has been made in view of the above, and an object thereof is to provide a power transmission device that can secure the amount of lubricating oil to a pinion shaft while suppressing an increase in the number of components, and can reduce the leakage amount. [[Means for Solving the Problem]]

[0006] A power transmission device according to the present disclosure includes: a planetary gear mechanism including a sun gear, a pinion gear, a ring gear, and a carrier that supports the pinion gear; and a rotating member disposed along a rotation center line of the planetary gear mechanism and rotating integrally with the sun gear, the power transmission device being configured to be capable of supplying lubricating oil to a bearing portion of the pinion gear, wherein a lubrication groove that guides the lubricating oil to tooth surfaces of the planetary gear mechanism is formed on an end face of the planetary gear mechanism.

[0007] In the power transmission device according to the present disclosure, the end face of the planetary gear mechanism is the end face of the pinion gear, and the lubrication groove is formed on at least one end face of the pinion gear.

[0008] The power transmission device according to the present disclosure, in the above disclosure, has end faces of the planetary gear mechanism which are the end face of the pinion gear and the end face of the carrier, and the lubrication groove is formed on the sliding surface portion between the end face of the pinion gear and the end face of the carrier. [Effects of the Invention]

[0009] According to this disclosure, it is possible to ensure sufficient lubrication oil for the pinion shaft while suppressing an increase in the number of parts, thereby reducing leakage. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic cross-sectional view showing a power transmission device according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a plan view showing one end face of a pinion gear according to one embodiment of the present disclosure. [Figure 3] Figure 3 is a plan view showing the other end face of a pinion gear according to one embodiment of the present disclosure. [Figure 4] Figure 4 is a cross-sectional view showing a schematic of a conventional power transmission device. [Figure 5] Figure 5 is a schematic diagram showing the oil flow between the tooth surface of the sun gear and the tooth surface of the pinion gear in a power transmission device according to one embodiment of the present disclosure, when the helix angle of the sun gear is to the right and the rotation of the pinion gear is in the forward direction. [Figure 6] Figure 6 is a schematic diagram showing the oil flow between the tooth surface of the sun gear and the tooth surface of the pinion gear in a power transmission device according to one embodiment of the present disclosure, when the helix angle of the sun gear is to the right and the rotation of the pinion gear is negative. [Modes for carrying out the invention]

[0011] The embodiments of this disclosure will be described below with reference to the drawings. In all the drawings of the embodiments described below, the same or corresponding parts will be denoted by the same reference numerals. Furthermore, this disclosure is not limited to the embodiments described below.

[0012] Patent Document 1 discloses a drive device that can reliably supply lubricating oil to the pinion shaft and improve lubricating oil performance, wherein the structure reduces the amount of lubricating oil leaking from the plates by using a double-layered plate structure with the outer edges fixed to the oil receiver for guiding the lubricating oil to the opening of the lubrication path of the pinion shaft.

[0013] In a structure that uses an oil receiver to guide the lubricating oil, leakage of lubricating oil from the opening between the receiver and the carrier can result in insufficient supply of lubricating oil to the pinion shaft, potentially leading to a decrease in lubrication performance. As described in Patent Document 1, a method to reduce leakage by stacking two receivers can be considered. However, this increases the number of parts and manufacturing steps, resulting in higher costs. Similarly, structures that guide lubricating oil directly to the pinion shaft by using resin for the receiver also suffer from the problem of increased costs.

[0014] In a design where lubricating oil supplied from an oil hole branched from the input shaft axis is discharged to the outer circumference by centrifugal force and caught by a receiver to guide it to the pinion shaft, if the receiver needs to be added after the pinion shaft is assembled in order to send the oil from the input shaft axis to the pinion shaft axis, lubricating oil will leak from the opening created during assembly. Reducing this leakage would require changing materials or adding leak-reducing parts, which raises concerns about increased costs.

[0015] Accordingly, the inventor of the present invention has conceived a hybrid drive device having two motors, namely a prime mover and a drive motor, comprising an input shaft for inputting output from the prime mover to the drive device, and a planetary gear mechanism for splitting output from the prime mover between the prime mover and an axle, wherein the input shaft has a shaft center oil hole for supplying lubricating oil, has a configuration capable of supplying lubricating oil to the shaft core of the pinion shaft by centrifugal oil pressure of the lubricating oil supplied through the branched oil hole, and is configured such that a lubricating oil groove capable of supplying lubricating oil to the pinion shaft is provided on an end face of a planetary gear that constitutes the planetary gear mechanism.

[0016] Specifically, the inventor has devised a mechanism in which a lubricating oil groove is provided at least on an end face of the pinion gear, and a lubricating oil groove is provided inside the carrier cover as necessary, so that when the pinion gear rotates, lubricating oil is taken into the inner radial needle bearing and the sliding surfaces of both end faces of the pinion gear through the lubricating groove. This enables the pinion gear to fulfill the function of the receiver in the above-mentioned prior art, and eliminates the need for machining a receiver and oil holes in the input shaft, the pinion shaft, etc. The embodiments of the present disclosure described below are conceived through the inventor's intensive studies mentioned above.

[0017] Next, a power transmission device according to an embodiment of the present disclosure will be described. FIG. 1 is a cross-sectional view showing the power transmission device according to the present embodiment. FIGS. 2 and 3 respectively show plan views of one end face and the other end face of a pinion gear used in the power transmission device according to the present embodiment.

[0018] As shown in FIG. 1, the drive device 1 according to the present embodiment will be described. In the present embodiment, an example will be described where the drive device is mounted on a hybrid vehicle including an engine and a motor generator as power sources, and is applied to a drive device (transaxle) for transmitting power generated by these power sources to drive wheels.

[0019] The drive device 1 according to the present embodiment includes a planetary gear mechanism 10 and a transaxle case 20. The planetary gear mechanism 10 functions as a power split mechanism that splits output of an engine (not shown) between a generator side and an output shaft side.

[0020] The planetary gear mechanism 10 is coupled to an input shaft 2 to which power from a power source such as an engine is input. The planetary gear mechanism 10 is housed in a transaxle case 20. The planetary gear mechanism 10 includes a sun gear 40 formed of a helical external gear, a pinion gear 50 formed of a helical external gear, a pinion shaft 51, a carrier 55, and a ring gear 60 formed of a helical internal gear.

[0021] The sun gear 40 is located at the center of the gear elements. The sun gear 40 is rotatably provided with the axis of the input shaft 2 serving as a rotating member as its rotation center line. One end side of the sun gear 40 is spline-fitted to a rotor shaft 6 of a generator. The other end side of the sun gear 40 is provided to mesh with the pinion gear 50.

[0022] The ring gear 60 is concentrically arranged on an outer diameter side of the sun gear 40. The ring gear 60 is rotatably attached to support portions 21 and 22 provided on the transaxle case 20 via ball bearings 71 and 72. The ring gear 60 is rotatably provided around the axis of the input shaft 2. The ring gear 60 has an output gear portion 61 formed on an outer peripheral portion thereof. The output gear portion 61 is drivingly connected to wheels via a counter gear mechanism (not shown) or the like.

[0023] The pinion gear 50 is arranged between the sun gear 40 and the ring gear 60 while meshing with the sun gear 40 and the ring gear 60. The pinion gear 50 is rotatably supported on the pinion shaft 51 via a needle bearing 54 serving as a bearing portion. The pinion gear 50 is provided to be capable of rotating (rotating on its own axis) around the central axis of the pinion shaft 51, and is also provided to be capable of rotating (revolving) around the central axis of the input shaft 2.

[0024] The carrier 55 holds the pinion shaft 51. The carrier 55 is fixed to a flange 5 provided on the input shaft 2. The carrier 55 is rotatably mounted integrally with the input shaft 2. This allows the planetary gear mechanism 10 to divide the engine output into mechanical power transmitted from the pinion gear 50, supported by the pinion shaft 51 held by the carrier 55, to the sun gear 40, and mechanical power transmitted to the ring gear 60.

[0025] Furthermore, as shown in Figures 2 and 3, a lubricating oil groove 52 is formed on the inside of a carrier (not shown in Figures 2 and 3) that slides against one end face of the pinion gear 50 according to this embodiment. Also, as shown in Figure 3, a lubricating oil groove 53 is formed on the other end face of the pinion gear 50.

[0026] A communication hole (not shown) extending along the axial direction is formed inside the oil pump drive shaft, and the oil discharged from the oil pump is supplied from one end to the other end of the oil pump drive shaft through the communication hole. The communication hole provided in the oil pump drive shaft communicates with a communication hole 3 provided inside the input shaft 2. The communication hole 3 extends along the axial direction of the input shaft 2 and communicates with a communication hole 4 provided so as to reach the outer circumferential surface of the input shaft 2.

[0027] As shown in Figure 1, lubricating oil is supplied from an oil pump (not shown) located on the central axis of the input shaft 2. The oil pump drive shaft transmits power from the input shaft 2 to the oil pump, thereby driving the oil pump and discharging oil.

[0028] As shown by the arrow in Figure 1, the lubricating oil supplied from the oil pump to the communication hole 3 of the input shaft 2 is supplied to the planetary gear mechanism 10 from the communication hole 4 by the centrifugal force generated by the rotation of the input shaft 2. Specifically, the lubricating oil is ejected radially outward from the communication hole 4 of the input shaft 2 and discharged into the transaxle case 20. The lubricating oil discharged into the transaxle case 20 is further moved radially outward from the input shaft 2 by centrifugal force.

[0029] Furthermore, as indicated by the arrows showing the flow of lubricating oil, the lubricating oil supplied to the end of the pinion gear 50 of the planetary gear mechanism 10 is captured by the lubricating oil grooves 52 and 53 of the pinion gear 50 and supplied to the pinion gear 50 and the pinion shaft 51. It is further supplied radially outward along the pinion shaft 51 (dotted arrow) by centrifugal hydraulic pressure and supplied to the tooth surface of the pinion gear 50.

[0030] Figures 5 and 6 are schematic diagrams showing the oil flow between the tooth surface of the sun gear and the tooth surface of the pinion gear in the power transmission device according to this embodiment, where the twist angle of the sun gear is to the right and the rotation of the pinion gear 50 is in the forward and negative directions, respectively.

[0031] As shown in Figure 5, when the pinion gear 50 is rotating in the forward direction (rotation arrow), an oil flow is generated along the tooth surfaces of the pinion gear 50 and the sun gear 40 so as to flow in the direction of rotation of the pinion gear 50 and the sun gear 40 (oil flow arrow). Similarly, as shown in Figure 6, when the pinion gear 50 is rotating in the negative direction (rotation arrow), an oil flow is generated along the tooth surfaces of the pinion gear 50 and the sun gear 40 so as to flow in the direction of rotation of the pinion gear 50 and the sun gear 40 (oil flow arrow). In other words, an oil flow is generated along the tooth surfaces of the pinion gear 50 and the sun gear 40 so as to flow the lubricating oil in the direction of rotation of the pinion gear 50 and the sun gear 40. This ensures that lubricating oil is supplied along the teeth of the pinion gear 50.

[0032] Figure 4 is a cross-sectional view showing a schematic of a conventional power transmission device for one embodiment described above. In Figure 4, the communication hole 103, flange portion 105, rotor shaft 106, support portions 121, 122, output gear portion 161, and ball bearings 171, 172 are the same as the communication hole 3, flange portion 5, rotor shaft 6, support portions 21, 22, output gear portion 61, and ball bearings 71, 72, respectively.

[0033] As shown in Figure 4, in the prior art, compared to the power transmission device according to the above-described embodiment, the pinion shaft 151 of the planetary gear mechanism 110 has an opening 152 provided at one end and an oil passage 153 communicating therewith. The oil passage 153 has a portion that extends in the axial direction of the pinion shaft 151 and a portion that extends radially from the portion that extends in the axial direction to reach the outer circumferential surface of the pinion shaft 151.

[0034] Furthermore, the oil receiver 130 is provided on one end of the pinion shaft 151, where the opening 152 is located. The oil receiver 130 is attached to the side of the carrier 155 and guides the lubricating oil toward the opening 152 in the pinion shaft 151. That is, the lubricating oil discharged into the transaxle case 120 moves radially outward of the input shaft 102 due to centrifugal force. The lubricating oil that has moved radially outward is guided by the oil receiver 130 to the opening 152 in the pinion shaft 151 and supplied to the oil passage 153 of the pinion shaft 151.

[0035] The lubricating oil supplied to the oil passage 153 is discharged by the centrifugal force generated by the rotation of the pinion shaft 151 from the portion of the oil passage 153 that extends radially to reach the outer circumferential surface of the pinion shaft 151, and is supplied to the needle bearing 154. This lubricates the needle bearing 154.

[0036] Furthermore, the lubricating oil supplied to the oil passage 153 is supplied to the meshing portion between the ring gear 160 and the pinion gear 150, lubricating both the ring gear 160 and the pinion gear 150. As the pinion gear 150 rotates, the lubricating oil is also supplied to the meshing portion between the pinion gear 150 and the sun gear 140. This lubricates the meshing portion between the pinion gear 50 and the sun gear 40.

[0037] Furthermore, when the oil receiver 130 guides the lubricating oil, the lubricating oil discharged from the communication hole 104 of the input shaft 102 into the transaxle case 120 is subjected to centrifugal force generated by the rotation of the input shaft 102. The lubricating oil that moves radially outward of the input shaft 102 due to the centrifugal force is held within the space 134.

[0038] According to the embodiment of the present disclosure described above, the pinion gear 50 can perform the function of the receiver in the prior art, eliminating the need to process the receiver and oil holes on the input shaft 2 and pinion shaft, thus ensuring sufficient lubrication oil for the pinion shaft while suppressing an increase in the number of parts, and reducing leakage.

[0039] Further effects and modifications can be readily derived by those skilled in the art. Broader aspects of this disclosure are not limited to the specific details and representative embodiments expressed and described above. Therefore, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents. [Explanation of Symbols]

[0040] 1: Drive unit 2: Input shaft 3,4:Communication hole 5: Tsuba (guard) 6: Rotor shaft 10: Planetary gear mechanism 20: Transaxle Case 21,22: Support part 40: Sangiya 50: Pinion gear 51: Pinion shaft 52,53: Lubricating oil groove 54: Needle bearing 55: Career 60: Ring gear 61: Output gear section 71,72: Ball bearings

Claims

1. A planetary gear mechanism comprising a sun gear, a pinion gear, a ring gear, and a carrier supporting the pinion gear, The planetary gear mechanism comprises a rotating member arranged along the rotational centerline and rotating integrally with the sun gear, A power transmission device configured to supply lubricating oil to the bearing portion of the pinion gear, Lubrication grooves are formed on the end face of the planetary gear mechanism to guide the lubricating oil to the tooth surface of the planetary gear mechanism. A power transmission device equipped with the following features.

2. The end face of the planetary gear mechanism is the end face of the pinion gear, and the lubrication groove is formed on at least one end face of the pinion gear. The power transmission device according to claim 1.

3. The end faces of the planetary gear mechanism are the end face of the pinion gear and the end face of the carrier, and the lubrication groove is formed on the sliding surface portion between the end face of the pinion gear and the end face of the carrier. The power transmission device according to claim 1 or 2.

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