Power transmission device

Abstract

To provide a power transmission device which can expand a lubrication range.SOLUTION: A power mechanism of a power transmission device including the power mechanism for transmitting a rotation force by using at least three of more rotating shafts, and a housing for covering the power mechanism comprises: a first gear which can rotate in a first rotation direction with an input shaft into which the rotation force is input as a center; and a second gear which can rotate in a second rotation direction opposite to the first rotation direction around an output shaft for outputting the rotation force transmitted from the first gear, and which can rotate at a position lower than a center of the input shaft in a vertical direction. The housing is formed with: an oil storage part for making the second gear immersed therein; a covering part which extends so as to cover about one quarter of an external periphery of the second gear along the second rotation direction from the lowest part of the second gear with respect to a tooth face of the second gear; and an oil supply path for supplying oil scooped accompanying the rotation of the second gear to the tooth face of the first gear by making the oil bypass along a side face of the first gear, which is arranged at a position higher than the center of the input shaft in the vertical direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a power transmission device. [Background technology]

[0002] Motors are used as the power source for electric vehicles and hybrid vehicles. When a gear mechanism is used as the power mechanism for transmitting the rotational force of such a motor, a lubrication method is required to reduce friction, wear, and heat generated by meshing between the gears.

[0003] Forced lubrication, in which lubricant is forcibly pumped to the parts to be lubricated, is known as a lubrication method used for gear mechanisms. However, when forced lubrication is adopted, there is a risk of an increase in space, cost, and mass due to the need to install an oil pump. To solve these problems, oil bath lubrication, as shown in Patent Document 1, for example, has been considered. In oil bath lubrication, oil in an oil reservoir is scooped up as the gear mechanism rotates, and the oil is supplied to the gear mechanism inside the housing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-002026 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when oil bath lubrication is adopted in a gear mechanism having three or more rotating shafts, there is a risk that sufficient oil may not be supplied to lubricate the gear furthest from the gear bathed in oil, due to the arrangement space within the housing.

[0006] The present invention has been made in view of the above circumstances, and has an object to provide a power transmission device capable of expanding the lubrication range. [Means for solving the problem]

[0007] This power transmission device includes a power mechanism that transmits a rotational force using at least three or more rotation shafts and a housing that covers the power mechanism. The power mechanism includes a first gear that can rotate in a first rotation direction about an input shaft to which a rotational force is input, and a second gear that can rotate in a second rotation direction opposite to the first rotation direction about an output shaft that outputs the rotational force transmitted from the first gear, the second gear being rotatable at a position lower than the center of the input shaft in the vertical direction, and the housing is formed with an oil reservoir that stores oil in which the second gear is immersed, a cover that extends from the bottom of the second gear along the second rotation direction with respect to the tooth surface of the second gear so as to cover approximately one-quarter of the outer periphery of the second gear, and an oil supply path that diverts oil scooped up as the second gear rotates along the side of the first gear to supply it to the tooth surface of the first gear, the oil supply path being provided at a position higher than the center of the input shaft in the vertical direction. Effect of the Invention

[0008] According to the present invention, a power transmission device capable of expanding the lubrication range is provided. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an example of a power transmission device according to a first embodiment. [Diagram 2] 2 is a cross-sectional view of the power transmission device according to the first embodiment taken along the line AA when viewed in the direction of the arrow. [Diagram 3] 2 is a partially enlarged view of the power transmission device according to the first embodiment taken along the line BB in FIG. [Figure 4A] 11A to 11C are perspective views showing a process in which the oil flow changes during the oil supply operation. [Figure 4B] 11A to 11C are perspective views showing a process in which the oil flow changes during the oil supply operation. [Figure 4C] 11A to 11C are perspective views showing a process in which the oil flow changes during the oil supply operation. [Diagram 5]FIG. 6 is a cross-sectional view of a power transmission device according to a second embodiment. [Figure 6] FIG. 11 is a view showing a power mechanism according to a second embodiment as viewed in the tooth surface direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components in each drawing are denoted by the same reference numerals as much as possible, and duplicated description will be omitted.

[0011] To explain the relative directional relationships, the direction of the right arrow on the paper in Fig. 1 is called the x-axis positive direction, the direction of the up arrow on the paper is called the y-axis positive direction, and the direction of the back arrow on the paper is called the z-axis positive direction. In addition, the drawings from Fig. 2 onwards will be explained based on the positive directions of the xyz axes arrows in Fig. 1.

[0012] First Embodiment FIG. 1 is a diagram showing an example of a power transmission device 1 according to the first embodiment. As shown in FIG. 1, the power transmission device 1 according to the first embodiment transmits a rotational force from a first motor 2 to a first shaft 4 via a first power mechanism 3, and from a second motor 5 to a second shaft 7 via a second power mechanism 6. In the power transmission device 1 according to the first embodiment, the first motor 2 and the second motor 5, the first power mechanism 3 and the second power mechanism 6, and the first shaft 4 and the second shaft 7 are formed symmetrically with respect to the center part of a housing 8. In addition, the power transmission device 1 according to the first embodiment may be equipped with an inverter (not shown) that controls the first motor 2 and the second motor 5. The power transmission device 1 may be used in, for example, an electric vehicle or a hybrid vehicle.

[0013] The first motor 2 inputs a rotational force to the first power mechanism 3. The first motor 2 may be supplied with power from a battery (not shown) and controlled via an inverter. The first motor 2 is, for example, a permanent magnet type synchronous motor.

[0014] The first power mechanism 3 transmits a rotational force using at least three or more rotating shafts. The first power mechanism 3 shown in FIG. 1 has four rotating shafts, and transmits the rotational force input from the first motor 2 to the first shaft 4 via a plurality of gear mechanisms. Specifically, the rotation speed of the first motor 2 is reduced, and the rotational force is increased and output to the first shaft 4. A detailed configuration of the first power mechanism 3 will be described later. Note that bearings may be provided on both ends of each gear of each of the four rotating shafts of the first power mechanism 3 so that the gears are rotatably supported. Note that the bearings may be rolling bearings such as ball bearings, roller bearings, etc.

[0015] The first shaft 4 rotates integrally with the wheels upon receiving the rotational force transmitted from the first power mechanism 3. The first shaft 4 is, for example, a CVJ (Constant Velocity Joint) capable of transmitting a rotational force to an axle connected to the wheels.

[0016] The second motor 5 inputs a rotational force to the second power mechanism 6. The second motor 5 may have a similar configuration to the first motor 2.

[0017] The second power mechanism 6 transmits a rotational force using at least three or more rotation shafts. The second power mechanism 6 may have a similar configuration to the first power mechanism 3.

[0018] The second shaft 7 receives the rotational force transmitted from the second power mechanism 6 and rotates integrally with the wheels. The second shaft 7 may have a similar configuration to the first shaft 4. In addition, the second shaft 7 and the first shaft 4 may be coaxial.

[0019] The housing 8 covers the first motor 2, the first power mechanism 3, the second motor 5, and the second power mechanism 6. The housing 8 may be configured by dividing it into a plurality of parts in order to assemble and house the first motor 2, the first power mechanism 3, the second motor 5, and the second power mechanism 6. Furthermore, the housing 8 may be provided with housing sections for housing inverters for driving the first motor 2 and the second motor 5 above each of them.

[0020] 2 is a view of the AA cross section of the power transmission device 1 according to the first embodiment, viewed in the direction of the arrow. As shown in FIG. 2, the first power mechanism 3 is housed in a space surrounded by the inner wall of the housing 8. The first power mechanism 3 is composed of a first gear 3a1, a second gear 3b1, a first transmission gear tg11, a second transmission gear tg21, and a third transmission gear tg31. The housing 8 is also formed with an oil reservoir OP1, a cover CP1, and an oil supply circuit OSP. The structure of the first power mechanism 3 described below may be the same as that of the second power mechanism 6, which is formed symmetrically across the center of the housing 8.

[0021] The first power mechanism 3 transmits, for example, a rotational force input to the input shaft IS1 to the first gear 3a1, the first transmission gear tg11, the second transmission gear tg21, the third transmission gear tg31, and the second gear 3b1 in this order. Due to the rotational force input from the first motor 2, the first gear 3a1 rotates about the input shaft IS1 in a first rotational direction R1 to transmit the rotational force to the first transmission gear tg11.

[0022] Due to the meshing of the first gear 3a1 and the first transmission gear tg11, the first transmission gear tg11 rotates in the direction opposite to the first rotational direction R1 and transmits the rotational force to the second transmission gear tg21.

[0023] Due to the meshing between the first transmission gear tg11 and the second transmission gear tg21, the second transmission gear tg21 rotates in the same direction as the first rotational direction R1 and transmits a rotational force to the third transmission gear tg31.

[0024] The third transmission gear tg31 has the same rotation axis as the second transmission gear tg21, and the third transmission gear tg31 rotates integrally with the second transmission gear tg21 in the same direction as the first rotation direction R1 to transmit rotational force to the second gear 3b1.

[0025] As a result of the third transmission gear tg31 and the second gear 3b1 meshing with each other, the second gear 3b1 rotates in a second rotational direction R2 opposite to the first rotational direction R1, and outputs a rotational force to the output shaft OS1.

[0026] The oil reservoir OP1 stores oil in which the second gear 3b1 is immersed. In the power transmission device 1 shown in Fig. 2, the oil reservoir OP1 is provided in the lower part of the housing 8, and is configured to store oil in which a part of the second gear 3b1 is immersed. In addition, a suction port (not shown) for adjusting the amount of oil may be formed in the lower part of the housing 8 in which the oil reservoir OP1 is formed.

[0027] The cover part CP1 may be formed on the tooth surface of the second gear 3b1 so as to cover about a quarter of the outer circumference of the second gear 3b1 from the lowest part of the second gear 3b1 along the second rotation direction R2. The cover part CP1 adjusts the oil scooping height of the second gear 3b1 upward so that the oil scooped up when the second gear 3b1 rotates in the second rotation direction R2 reaches the height of the oil supply path OSP in the vertical direction (positive y-axis direction). That is, the cover part CP1 is provided on the housing 8, and the oil is sent from the cover part CP1 along the inner wall of the housing 8 by the rotation of the second gear 3b1 in the second rotation direction R2, making it easier for the oil to reach the height of the oil supply path OSP.

[0028] The oil supply path OSP diverts the oil scooped up with the rotation of the second gear 3b1 along the side surface sf of the first gear 3a1 and supplies the oil to the tooth surface tf of the first gear 3a1. The oil supply path OSP is provided inside the housing 8. The oil supply path OSP is provided at a position higher than the center of the input shaft IS1 in the vertical direction (positive y-axis direction). The oil supply path OSP may be inclined downward (negative y-axis direction) toward the positive z-axis direction. With this configuration, the oil that reaches the height of the oil supply path OSP rides on the guide path gp and flows by its own weight toward the supply path sp.

[0029] 3 is a partially enlarged view of the BB cross section of the power transmission device 1 according to the first embodiment, viewed in the direction of the arrow. As shown in FIG. 3, the oil supply path OSP is composed of a guide path gp and a supply path sp. The guide path gp is formed in the x-axis direction from the second transmission gear tg21 to the third transmission gear tg31 as shown in the figure. The supply path sp is formed in a detour along the side surface sf of the first gear 3a1 toward the z-axis positive direction as shown in the figure. The guide path gp and the supply path sp may be inclined downward (y-axis negative direction) toward the z-axis positive direction. With this configuration, the oil that reaches the height of the guide path gp in the vertical direction (y-axis positive direction) rides on the guide path gp and flows by its own weight.

[0030] Since the rotation of first gear 3a1 in first rotation direction R1 is in a direction that obstructs the direction of travel of the oil scooped up by second gear 3b1 (the positive direction of the z axis), the amount of oil supplied to the tooth surface tf of the positive direction of the z axis of first gear 3a1 is small. However, by providing oil supply path OSP, the oil can be detouring along side surface sf of first gear 3a1 and supplied to the tooth surface tf of the positive direction of the z axis of first gear 3a1, so the lubrication range can be expanded.

[0031] 4A to 4C are perspective views showing the oil supply path OSP during the oil supply operation, in which the oil flow changes. As shown in the drawings, the oil scooped up by the second gear 3b1 gradually flows from the guide portion gp of the oil supply path OSP along the supply path sp.

[0032] 4A is a perspective view showing a process in which the oil flow changes during the oil supply operation. The second gear 3b1 rotates and scoops up the oil.

[0033] 4B is a perspective view showing the middle of a process in which the oil flow changes during the oil supply operation. The oil scooped up by the second gear 3b1 rides on the guide portion gp along the inner wall of the housing 8 and flows toward the supply path sp under its own weight.

[0034] 4C is a perspective view showing a process in which the oil flow changes during the oil supply operation. The oil flowing through the supply path sp detours along the side surface sf of the first gear 3a1.

[0035] As described above, according to the power transmission device 1 according to the first embodiment, by providing the oil reservoir OP1, the cover portion CP1, and the oil supply path OSP in the housing 8, the range of lubrication by oil can be expanded.

[0036] <Second embodiment> 5 is a cross-sectional view of a power transmission device 10 according to a second embodiment. The power transmission device 10 according to the second embodiment shown in FIG. 5 is a cross-sectional view similar to the AA cross section of the power transmission device 1 shown in FIG. 1. The power transmission device 10 according to the second embodiment shown in FIG. 5 is different from the power transmission device 1 according to the first embodiment in that an oil retention section OH is provided instead of the oil supply path OSP shown in FIG. 2. Note that the configurations and rotation directions of the first power mechanism 30, the housing 80, the oil storage section OP2, the cover section CP2, etc. constituting the power transmission device 10 according to the second embodiment are the same as those of the power transmission device 1 according to the first embodiment, and therefore will not be described here.

[0037] The oil retaining portion OH may be formed continuously along the tooth surfaces of the first gear 3a2, the first transmission gear tg12, and the second transmission gear tg22 and the meshing portion of each gear. The oil retaining portion OH is configured to accumulate oil scooped up as the second gear 3b2 rotates. By providing a configuration in which the oil retaining portion OH accumulates and retains oil in this manner, the lubrication range can be expanded. For example, the first transmission gear tg12 scoops up the oil accumulated in the oil retaining portion OH and can supply it to the tooth surface of the first gear 3a2 in the z-axis positive direction. The oil retaining portion OH may be formed discontinuously in a similar shape.

[0038] Fig. 6 is a view of the power mechanism 30 according to the second embodiment as viewed in the tooth surface direction. The first power mechanism 30 and the oil retention unit OH have a positional relationship as shown in Fig. 6. Specifically, the oil retention unit OH is formed so as to cover the width direction of the tooth surfaces of the first gear 3a2, the first transmission gear tg12, and the second transmission gear tg22 in the x-axis direction along the tooth surfaces of each gear and the meshing portions of the gears.

[0039] As described above, according to the power transmission device 10 according to the second embodiment, by providing the oil reservoir OP2, the cover portion CP2, and the oil retention portion OH in the housing 80, the lubrication range of the oil can be expanded.

[0040] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Any design modifications made by a person skilled in the art to these specific examples are also included within the scope of the present disclosure as long as they have the features of the present disclosure. The elements of each of the above-mentioned specific examples and their arrangements, conditions, shapes, etc. are not limited to those exemplified and can be changed as appropriate. The combination of each of the elements of each of the above-mentioned specific examples can be changed as appropriate as long as no technical contradiction occurs. [Explanation of symbols]

[0041] 1,10: Power transmission device 2: First motor 3,30: 1st power mechanism 4: 1st shaft 5: Second motor 6:Second power mechanism 7: 2nd shaft 8,80:Housing 3a1, 3a2: 1st gear 3b1, 3b2: 2nd gear IS1, IS2; Input shaft OS1, OS2: Output shaft OP1, OP2: Oil storage part CP1, CP2: Covering part OSP: Oil supply path OH: Oil holding part R1: First rotation direction R2: Second rotation direction tg11, tg12: 1st transmission gear tg21, tg22: 2nd transmission gear tg31, tg32: 3rd transmission gear

Claims

[Claim 1] A power transmission device including a power mechanism that transmits a rotational force using at least three or more rotation shafts and a housing that covers the power mechanism, The power mechanism includes: a first gear rotatable in a first rotational direction around an input shaft to which a rotational force is input; a second gear that is rotatable in a second rotation direction opposite to the first rotation direction around an output shaft that outputs the rotational force transmitted from the first gear, the second gear being rotatable at a position lower than the center of the input shaft in a vertical direction; Equipped with The housing includes: an oil reservoir in which oil is stored and in which the second gear is immersed; a cover portion extending from a lowermost portion of the second gear along the second rotation direction with respect to a tooth surface of the second gear so as to cover approximately one-fourth of an outer periphery of the second gear; an oil supply path that diverts oil scooped up in accordance with rotation of the second gear along a side surface of the first gear to supply oil to a tooth surface of the first gear, the oil supply path being provided at a position higher than a center of the input shaft in a vertical direction; A power transmission device formed.

Images