Lubrication device for motor drive unit

Abstract

To provide a lubrication device that can ensure a supply of lubricating oil while suppressing oil film breakdown as much as possible. [Solution] The lubrication device 1 for a motor drive unit in which a rotating shaft 101, which rotates by torque transmitted from the rotor shaft 4 of a motor 3, is arranged parallel to the rotor shaft 4, has a blade 102 that rotates to generate an axial wind directed in the axial direction of the rotating shaft 101, and is attached to the rotating shaft 101 so as to extend outward in the radial direction of the rotating shaft 101, and a plate portion 103 is provided at the tip of the blade 102 to scoop up lubricating oil that has accumulated at a lower position than the motor rotor. As a result, when the rotor shaft 4 rotates, the blade 102 rotates together with the rotating shaft 101, so an axial wind is generated directed in the axial direction of the rotating shaft 101, and this axial wind carries heat, so the lubricating oil and rotating shaft are cooled by so-called air cooling. Therefore, it is possible to prevent or suppress the temperature rise of the lubricating oil and the resulting oil film breakdown.

Description

Technical Field

[0005]

[0001] This invention relates to an apparatus for lubricating a motor drive unit having a transmission mechanism for transmitting the output torque of a motor to the outside with lubricating oil.

Background Art

[0002] As is well known, lubricating oil is supplied to sliding parts in various mechanical devices to reduce friction and cooling, and a lubricating structure that scrapes up the lubricating oil stored at the bottom of the casing by the rotation of a rotating body such as a gear has been conventionally known.

[0003] For example, Patent Document 1 describes an electric drive device having a reduction gear with a stepped pinion type planetary gear, wherein a rectifying ring is provided on the outer periphery of the stepped pinion gear, and a scraping member for scraping up lubricating oil to a tank is further provided on a side surface portion or an outer peripheral portion of the rectifying ring.

[0004] In the device described in Patent Document 1, the rectifying ring confines the turbulent flow of lubricating oil generated by the rotation of the pinion gear within the rectifying ring so as not to affect the main flow of the lubricating oil. Further, by providing the scraping member on the rectifying ring, the lubricating oil can be efficiently scraped up to the tank, and it is said that the drag resistance of the rotor in the motor (the resistance when the rotor rotates against the lubricating oil) can be reduced.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Patent Document 1 describes a system in which a scraping member is provided on the flow rectifier ring to supply lubricating oil to the sliding parts. However, in the motor configuration described in Patent Document 1, the stirring resistance of the scraping member and the sliding resistance may cause the temperature of the lubricating oil to rise, potentially reducing the viscosity of the lubricating oil. When the viscosity of the lubricating oil decreases, the oil film of gears and bearings is more likely to break down, which can lead to increased wear and seizure of sliding parts.

[0007] This invention was made in view of the above-mentioned technical problems, and aims to provide a lubrication device that can ensure the supply of lubricating oil while suppressing oil film breakdown as much as possible. [Means for solving the problem]

[0008] To achieve the above objective, this invention provides a lubrication device for a motor drive unit in which a rotating shaft, which is rotated by torque transmitted from the rotor shaft of a motor, is arranged parallel to the rotor shaft, characterized in that a blade that generates an axial wind in the axial direction of the rotating shaft by rotating is attached to the rotating shaft in a manner that extends outward in the radial direction of the rotating shaft, and a plate portion is provided at the tip of the blade to scoop up lubricating oil accumulated at a position lower than the rotor of the motor. [Effects of the Invention]

[0009] According to the lubrication device of this invention, when the rotor shaft rotates to output torque from the motor, the rotating shaft, which is arranged parallel to the rotor shaft, also rotates. As the blades rotate together with the rotating shaft, an axial airflow is generated in the direction of the axis of the rotating shaft, and this axial airflow carries heat, so the lubricating oil and the rotating shaft are cooled by a so-called air cooling effect. As a result, it is possible to prevent or suppress the rise in temperature of the lubricating oil and the resulting breakdown of the oil film. In addition, since the plate portion provided at the tip of the blades scoops up the lubricating oil, even if the rotor shaft and rotating shaft are positioned higher than the oil level, sufficient lubricating oil can be supplied to these rotor shafts, rotating shafts, and even their supporting parts such as bearings. [Brief explanation of the drawing]

[0010] [Figure 1] This is a skeleton diagram of a motor drive unit equipped with a lubrication device according to the embodiment. [Figure 2] An example of the blade configuration is shown, where (a) is a perspective view of the blade and (b) is a front view of the blade attached to the counter shaft. [Modes for carrying out the invention]

[0011] The lubrication device 1 of the motor drive unit in this invention is part of a power transmission mechanism 2 that transmits power from a driving force source such as an engine or electric motor mounted on a vehicle to the drive wheels, and is installed for the purpose of supplying lubricating oil to the power transmission mechanism 2.

[0012] Figure 1 is a skeleton diagram showing the configuration of the power transmission mechanism 2 and lubrication device 1, which are motor drive units in an embodiment of this invention. The upper side of Figure 1 is the front side of the vehicle, and the lower side is the rear side of the vehicle. The power transmission mechanism 2 has a rotor shaft 4 that rotates by the output torque of a rotor (not shown) of an electric motor (hereinafter referred to as "motor") 3 and rotates together with the rotor, supported by a bearing 5. An output gear 6 is attached to the rotor shaft 4, and the output gear 6 meshes with a counter driven gear 7 which has a larger diameter than the output gear 6. The counter driven gear 7 is attached to a counter shaft 8 and rotates together with a counter drive gear 9 which has a smaller diameter than the counter driven gear 7, on the coaxial line of the counter shaft 8 and on the right side in the left-right direction of the vehicle. A differential ring gear 10 which has a larger diameter than the counter drive gear 9 meshes with the counter drive gear 9. The differential ring gear 10 is a gear that constitutes part of the final reduction gear, which distributes and transmits the drive torque to the left and right axles or wheels (not shown) via the differential shaft 11, which rotates together with it. In addition, the large-diameter gears, the counter-driven gear 7 and the differential ring gear 10, have multiple weight-reducing holes (not shown) formed in the gear flange portion.

[0013] The rotor shaft 4 and differential shaft 11 are aligned in the same row and parallel to each other in the left-right direction of the vehicle, while the counter shaft 8 is mounted further forward and parallel to the rotor shaft 4 and differential shaft 11 in the front-rear direction of the vehicle. Furthermore, the rotor shaft 4, counter shaft 8, and differential shaft 11 are positioned at the same height in the vertical direction of the vehicle (perpendicular to the plane of the paper in Figure 1).

[0014] Along with the gears and other rotating components described above, oil (hereinafter referred to as lubricating oil) is sealed inside a casing (not shown). The casing is sealed in a liquid-tight manner.

[0015] The output gear 6 is for outputting power from the motor 3's drive source to the counter-driven gear 7. The output power is transmitted to the counter-drive gear 9, which is on the same axis as the counter-driven gear 7, and then to the differential ring gear 10, which meshes with the counter-drive gear 9, distributing and transmitting the drive torque to the left and right axles or wheels.

[0016] Next, the scraping lubrication device of the present invention will be described with reference to Figures 1 and 2. In this embodiment of the invention, the lubrication device 1 scrapes up the lubricating oil stored at the bottom of the casing and supplies the lubricating oil to the rotating member described above.

[0017] The lubrication device 1 is positioned between the counter-driven gear 7 and the counter-drive gear 9 and is mounted on the counter shaft 8, which is positioned parallel to the rotor shaft of the motor 3. In other words, it consists of a cylindrical body 101 that rotates together with the counter shaft 8, which rotates due to torque transmitted from the rotor shaft of the motor 3, and plate-shaped blade portions 102 and 103.

[0018] Specifically, the cylindrical body 101 is spline-coupled to, for example, the counter shaft 8 or the counter driven gear 7 by spline grooves (not shown). The blade portion 102 is a plate-shaped member attached to the outer circumferential surface of the cylindrical body 101, extending radially outward, and arranged at equal intervals in the circumferential direction. The blade portion 102 has a predetermined twist angle with respect to the central axis of the counter shaft 8, from the cylindrical body 101 to the plate portion 103 at the end. Due to the twist angle, when the cylindrical body 101 rotates, the blade portion 102 generates an axial wind directed in the axial direction of the cylindrical body 101, creating a propeller-like air-blowing effect. In this embodiment, the shape of the blade portion 102 is plate-shaped, but it is not limited to this; it may be curved as shown in Figure 2(a), or the width (circumferential width) of the blade portion 102 may be increased towards the end. In other words, the propeller shape could be one with a small aspect ratio between the circumferential width and radial length, similar to that of a conventional fan.

[0019] Next, the plate-shaped plate portion 103 formed at the end of the blade portion 102 is a member for scooping up lubricating oil. For example, as shown in Figure 2(a), the plate portion has a curved surface that is concave with respect to the axis of rotation in the circumferential direction, but it is not limited to this, and it may also have a spoon-like shape that can hold a predetermined amount of lubricating oil at its end, like a water turbine, one of the conventional rotating machines. Figure 2(b) is a front view of the lubrication device 1 as seen from the rear side in the front-rear direction of the vehicle, and the height of the lubricating oil level 104 is indicated by a dashed line. Note that this oil level height 104 is such that the rotor of the motor 3 is not submerged. In other words, the plate portion 103 is configured to scoop up lubricating oil that has accumulated at a position lower than the rotor of the motor 3 (not shown) at the tip of the blade portion 102.

[0020] When the rotor shaft 4 rotates for the motor 3 to output torque, the counter shaft 8 arranged parallel to the rotor shaft 4 rotates. And on the outer periphery of the cylindrical body 101 that rotates integrally with the counter shaft 8, plate-shaped blade parts 102 having a torsional angle of a predetermined angle are arranged at equal intervals in the circumferential direction. Thereby, when the cylindrical body 101 rotates, the blade parts 102 also rotate together, and the fluid around the blade parts 102 having a torsional angle is pushed out, generating a blowing action in the rotational axis direction. Since the axial wind carries heat, lubricating oil, sliding members, etc. are cooled by a so-called air-cooling action. Therefore, it is possible to lower the temperature inside the casing and prevent or suppress the temperature rise of the lubricating oil and the accompanying oil film breakdown.

[0021] And since a plate-shaped plate part 103 for scraping up the lubricating oil is formed at the tip of the blade part 102, even if sliding members such as the rotor shaft 4 and the rotating shaft are arranged at a position higher than the oil level, the lubricating oil can be scraped up by the plate part 103, so that the lubricating oil can be forcibly and sufficiently supplied to the sliding members. Further, since a plurality of relief holes (not shown) are formed in the gear flange portions of the counter driven gear 7 and the defring gear 10 which are large-diameter gears, when the lubricating oil scatters, it passes through the relief holes in the flange portions and is supplied to the bearing 5 and the gear body. As a result, while ensuring the supply of the lubricating oil, it is possible to suppress oil film breakdown as much as possible.

[0022] Note that the above-described embodiments are merely examples of implementing the present invention and do not limit the present invention. For example, the power transmission mechanism targeted by the present invention may be provided with lubrication structures for both pumping lubrication as well as scraping-up lubrication. In pumping lubrication, it may be configured to perform lubrication by an oil pump attached to the casing. Further, when it is desired to actively supply lubricating oil to the bearing 5, for example, an arc-shaped protrusion capable of temporarily storing the lubricating oil may be provided inside the casing or on the bearing 5.

Explanation of Reference Numerals

[0023] 1 Lubrication device 2 Power transmission mechanism 3. Motor (electric motor) 4 rotor shafts 5 bearings 6 Output gears 7 Counter Driven Gear 8 counter axis 9 Counter drive gear 10 Differential ring gear 11 Differential shaft 101 Cylindrical body 102 Blade section 103 Board part 104 Oil level height

Claims

[Claim 1] A lubrication device for a motor drive unit in which a rotating shaft, which rotates by torque transmitted from the rotor shaft of the motor, is arranged parallel to the rotor shaft, A blade that rotates to generate an axial airflow directed in the axial direction of the rotating shaft is attached to the rotating shaft so as to extend outward in the radial direction of the rotating shaft, and a plate portion is provided at the tip of the blade to scoop up lubricating oil that has accumulated at a lower position than the rotor of the motor. A lubrication device for a motor drive unit, characterized by the following features.

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