Lubrication device and lubrication method for gear

Abstract

To realize excellent cooling and lubrication by supplying a small amount of lubricant to a high-speed rotating gear.SOLUTION: A gear lubrication device 200 comprises: a drive gear 14a (18a) and a driven gear 14b (18b) that mesh with each other; a rectifying block 30 that is arranged on a disengagement side of the drive gear 14a (18a) and the driven gear 14b (18b), and generates negative pressure between itself and at least one of the drive gear 14a (18a) and the driven gear 14b (18b); and oil supply means 32 that supplies oil between at least one of the drive gear 14a (18a) and the driven gear 14b (18b) and the rectifying block 30.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a gear lubrication device and a gear lubrication method. [Background technology]

[0002] Splash (oil bath) lubrication and forced lubrication are used as lubrication methods for gears used in the drivetrains of vehicles such as electric and hybrid vehicles. Forced lubrication methods include drip, injection (oil jet), and spray (oil air) types. The injection (oil jet) type is often used for gears directly connected to the motor shaft, which has the highest rotational speed.

[0003] The higher the torque transmitted between gears, the greater the friction loss on the tooth surface, causing the tooth surface temperature to rise. Meanwhile, increasing the amount of oil supplied to the gears increases the cooling capacity and decreases the tooth surface temperature. However, it is known that, in the range where the oil supply rate is 1.2 L / min or more, simply increasing the oil supply rate is not enough to improve the cooling effect.

[0004] Furthermore, as an example of improved lubrication for high-speed gears, a lubrication device has been disclosed in which a straightening block (shroud) is placed with a small gap on the outside of the tooth tip of the gear to suppress turbulence on the outer periphery of the gear, making it easier for oil mist to reach the tooth surface (Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-162884 Summary of the Invention [Problem to be solved by the invention]

[0006] When gears used in drivetrains rotate at high speeds, it is desirable to achieve good cooling and lubrication with a small amount of oil. Motors used in vehicles such as electric cars are becoming faster (for example, around 17,000 rpm) in order to reduce the size of the entire drive unit. The peripheral speed of the tips of the teeth of gears directly connected to a motor is determined by the motor's rotational speed, and for a gear with a tip diameter of 50 mm, this can reach 44.5 m / s when rotating at a high speed of 17,000 rpm.

[0007] On the other hand, as the gear peripheral speed increases, the mechanical loss caused by stirring the oil increases, so it is desirable to reduce the amount of oil supplied to the gear. However, if the tooth surface is not cooled sufficiently, the tooth surface temperature will rise, which may lead to damage such as scoring, so currently, excessive oil is supplied. [Means for solving the problem]

[0008] One aspect of the present invention is a gear lubrication device comprising: a first gear and a second gear that mesh with each other; a rectifying block that is disposed on the disengaging side of the first gear and the second gear and generates negative pressure between at least one of the first gear and the second gear; and oil supply means that supplies oil between at least one of the first gear and the second gear and the rectifying block.

[0009] Here, it is preferable that the rectifying block has a length equal to or greater than the tooth tip pitch length along the circumferential direction of the first gear and the second gear.

[0010] It is also preferable that the gap between at least one of the first gear and the second gear and the rectifying block is 0.5 mm or more and 2 mm or less.

[0011] Preferably, the first gear and the second gear are helical gears.

[0012] It is also preferable to provide a second oil supply means for supplying oil to the meshing start side of the first gear and the second gear.

[0013] Another aspect of the present invention is a method for lubricating gears, characterized in that a straightening block is disposed on the disengagement side of a first gear and a second gear that are meshed with each other, and negative pressure is generated between at least one of the first gear and the second gear and the straightening block, and oil is supplied between the first gear and the second gear and the straightening block. [Effects of the Invention]

[0014] According to the present invention, it is possible to achieve good cooling and lubrication for gears rotating at high speeds by supplying less lubricating oil than conventionally. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram illustrating an example of the configuration of a drive unit of a vehicle according to an embodiment of the present invention. [Figure 2] 1 is a diagram showing a configuration of a gear lubrication device according to an embodiment of the present invention; [Figure 3] 1 is a diagram showing a configuration of a specific example of a gear lubrication device according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0016] 1 shows an example of the configuration of a vehicle drive unit 100 to which the gear lubrication device of the present invention is applied. The vehicle drive unit 100 includes a motor 10, a drive shaft 12, a first stage gear mechanism 14 (drive gear 14a and driven gear 14b), a transmission shaft 16, a second stage gear mechanism 18 (drive gear 18a and driven gear 18b), an axle 20, a tire 22, an oil pump 24, and an oil supply pipe 26.

[0017] A drive shaft 12 is rotated by a motor 10. The rotation of the drive shaft 12 is reduced and transmitted from a drive gear 14a to a driven gear 14b by a first-stage gear mechanism 14. The driven gear 14b is fixed to a transmission shaft 16. The transmission shaft 16 is rotated in accordance with the rotation transmitted to the driven gear 14b. The rotation of the transmission shaft 16 is reduced and transmitted from a drive gear 18a to a driven gear 18b by a second-stage gear mechanism 18. The driven gear 18b is fixed to an axle 20. The axle 20 is rotated in accordance with the rotation transmitted to the driven gear 18b. The axle 20 is fixed to a tire 22. The tire 22 rotates in accordance with the rotation of the axle 20.

[0018] The vehicle drive unit 100 also includes an oil pump 24 and an oil supply pipe 26 that supply oil for cooling and lubrication to each part, including the first stage gear mechanism 14 and the second stage gear mechanism 18. The oil for cooling and lubrication is pressurized by the oil pump 24 and supplied to each part of the drive unit 100 through the oil supply pipe 26.

[0019] 2 shows the configuration of a gear lubrication device 200 according to an embodiment of the present invention. The gear lubrication device 200 includes a rectifying block 30 and oil supply means 32. The gear lubrication device 200 is used in combination with the drive gear 14a and driven gear 14b of the first stage gear mechanism 14 or the drive gear 18a and driven gear 18b of the second stage gear mechanism 18.

[0020] The following description will be given of a case where the gear lubrication device 200 is applied to the first stage gear mechanism 14, but the same applies when it is applied to the second stage gear mechanism 18.

[0021] The rectifying block 30 is disposed on the disengaged side of the drive gear 14a and the driven gear 14b. The rectifying block 30 has a thickness in a direction along the rotation axes of the drive gear 14a and the driven gear 14b (the depth direction in the drawing). The rectifying block 30 is disposed along the circumferential direction of the tooth tips of the drive gear 14a and the driven gear 14b, with a slight gap secured so as not to come into contact with the tooth tips. The gap is preferably large enough to prevent contact between the drive gear 14a or the driven gear 14b and the rectifying block 30 and to allow oil to be trapped between the drive gear 14a or the driven gear 14b and the rectifying block 30, as described below. The gap may be set appropriately depending on the diameters of the drive gear 14a and the driven gear 14b, but is preferably set to, for example, 0.5 mm or more and 2 mm or less.

[0022] Here, the "starting meshing side" of the gears refers to the side of the region where the drive gear 14a and the driven gear 14b change from a non-mesh state to a meshed state as the gears rotate, and the "disengaging side" of the gears refers to the side where the drive gear 14a and the driven gear 14b change from a meshed state to a disengaged state as the gears rotate.

[0023] The rectifying block 30 is provided with an oil supply means 32. The oil supply means 32 is connected to the oil pump 24 via the oil supply pipe 26. The oil supply means 32 also includes a nozzle 32a. The nozzle 32a is directed toward a portion (disengagement region) on the disengagement side of the drive gear 14a and the driven gear 14b where the meshing between the drive gear 14a and the driven gear 14b begins.

[0024] By supplying oil from the oil pump 24 to the oil supply means 32 via the oil supply pipe 26, oil can be supplied from the nozzle 32a toward the disengagement region of the drive gear 14a and the driven gear 14b.

[0025] The operation of the gear lubrication device 200 according to the embodiment of the present invention will be described below. With reference to Fig. 2, states (1) to (6) of the drive gear 14a and the driven gear 14b will be described along the rotation direction.

[0026] State (1) is a state in which the drive gear 14a and the driven gear 14b are completely disengaged (fully open state). At this time, the pressure between the drive gear 14a and the driven gear 14b is the same as the external pressure (reference pressure). Thereafter, as the driven gear 14b rotates, the teeth of the drive gear 14a enter the tooth grooves of the drive gear 14a, displacing the air in the tooth grooves of the drive gear 14a and the driven gear 14b, resulting in a partially closed state (state (2)). At this time, the pressure between the drive gear 14a and the driven gear 14b becomes a positive pressure higher than the external pressure (reference pressure). Furthermore, the drive gear 14a and the driven gear 14b are completely engaged, resulting in a fully closed state (state (3)). Thereafter, the driven gear 14b begins to disengage from the drive gear 14a, resulting in a partially open state (state (4)). At this time, the pressure between the drive gear 14a and the driven gear 14b becomes a negative pressure lower than the external pressure (reference pressure). As the meshing disengages, the state becomes a fully open state (state (5)) in which a closed space is formed between the rectifying block 30 and the drive gear 14a. At this time, the pressure between the drive gear 14a and the driven gear 14b becomes a weak negative pressure that is slightly lower than the external pressure (reference pressure). Finally, the tip of the tooth of the drive gear 14a also disengages from the rectifying block 30, and the state returns to a fully open state (state (6)). At this time, the pressure between the drive gear 14a and the driven gear 14b also returns to the same as the external pressure (reference pressure).

[0027] In the half-open state (state (4)), negative pressure is generated in the tooth grooves of the drive gear 14a as the teeth of the driven gear 14b try to disengage. The pressure from the oil pump 24 and the negative pressure act to efficiently fill the tooth grooves of the drive gear 14a with oil supplied from the oil supply means 32. The filled oil remains in the tooth grooves of the drive gear 14a by the rectifying block 30 until the fully open state (state (6)) is reached, ensuring time for the tooth surface of the drive gear 14a to cool. Thereafter, when the fully open state (state (6)) is reached, the cooled oil is discharged by centrifugal force, completing the cooling process.

[0028] The cooling time of the drive gear 14a by the oil is determined by the length L1 of the gap between the drive gear 14a and the rectifying block 30. In other words, it is determined by the length L1 of the surface of the rectifying block 30 along the circumferential direction of the drive gear 14a. It is preferable that the length L1 be equal to or greater than the pitch length P1 of the tooth tips of the drive gear 14a. This ensures that the area that retains the oil in the tooth grooves of the drive gear 14a is long enough for cooling, allowing the drive gear 14a to be sufficiently cooled by the oil.

[0029] When the drive gear 14a and driven gear 14b are disengaged from each other, the flow between the driven gear 14b and the flow rectifying block 30 also enters a fully open flow rectification state, and then the tooth tips of the driven gear 14b also disengage from the flow rectifying block 30, returning to the fully open state.

[0030] Therefore, similar to the drive gear 14a, in the half-open state, negative pressure is generated in the tooth grooves of the driven gear 14b as the teeth of the drive gear 14a try to disengage. The pressure from the oil pump 24 and the negative pressure work together to efficiently fill the tooth grooves of the driven gear 14b with oil supplied from the oil supply means 32. The filled oil remains in the tooth grooves of the driven gear 14b by the rectifying block 30 until the fully open state is reached, ensuring time for the tooth surface of the driven gear 14b to cool. Thereafter, when the fully open state is reached, the cooled oil is discharged by centrifugal force, completing the cooling process.

[0031] Here, the cooling time of the driven gear 14b by the oil is determined by the length L2 of the gap between the driven gear 14b and the rectifying block 30. In other words, it is determined by the length L2 of the surface of the rectifying block 30 along the circumferential direction of the driven gear 14b. It is preferable that the length L2 be equal to or greater than the pitch length P2 of the tooth tips of the driven gear 14b. This ensures that the area that retains the oil in the tooth grooves of the driven gear 14b is long enough for cooling, and the driven gear 14b can be sufficiently cooled by the oil.

[0032] The driven gear 14b has more teeth than the drive gear 14a, so the work per tooth is less and the tooth surface temperature is lower than that of the drive gear 14a. Therefore, the gap between the driven gear 14b and the commutating block 30 may be increased, or the commutating block 30 may not be provided on the driven gear 14b side. This allows oil to be discharged early on the driven gear 14b side, reducing the resistance of oil to the rotation of the driven gear 14b.

[0033] Fig. 3 shows a specific example of a gear lubrication device 200 according to an embodiment of the present invention. Fig. 3 shows a perspective view in which the drive gear 14a (18a) and the driven gear 14b (18b) are helical gears having a helix angle θ. Note that in Fig. 3, the rectifying block 30 is shown semi-transparently for clarity of explanation.

[0034] In this specific example, the oil supply means 32 is provided with a plurality of (six) nozzles 32a along the width W1 direction of the flow straightening block 30. This allows oil to be effectively supplied along the tooth width direction of the drive gear 14a and the driven gear 14b.

[0035] Furthermore, it is preferable that the width W1 of the flow straightening block 30 along the axial direction of the gears be equal to or greater than the face width W2 of the drive gear 14a and driven gear 14b along the axial direction, thereby improving the effect of generating negative pressure on the drive gear 14a and driven gear 14b and achieving highly efficient oil retention.

[0036] Furthermore, by applying gear lubrication device 200 to a helical gear with a helix angle θ, oil supplied to position (a) is pushed aside by the twisted tooth flanks and sent along the axial direction of the gears from position (b) to position (c), and is also discharged from the ends of drive gear 14a and driven gear 14b. In this way, the oil flows along the tooth flanks, improving the cooling ability of the tooth flanks.

[0037] However, the scope of application of the gear lubrication device 200 is not limited to helical gears, but can also be applied to other types of gears such as spur gears.

[0038] In this embodiment, the straightening block 30 is disposed on the disengagement side of the gears, and oil is not supplied to the meshing start side. However, this is not limiting. A conventional oil jet system or the like may also be used as a second oil supply means on the meshing start side of the gears. In this case, it is preferable to supply the minimum amount of oil necessary for lubrication from the meshing start side and to activate the lubrication device 200 only when the temperature of the tooth surface is high. For example, oil may be supplied only to the meshing start side when the gear rotation speed is low, and the amount of oil supplied to the disengagement side by the lubrication device 200 may be increased as the rotation speed increases. This allows for more efficient lubrication and cooling of the tooth surface.

[0039] As described above, according to the gear lubrication device 200 of this embodiment, it is possible to achieve good cooling and lubrication of gears rotating at high speeds by supplying less lubricating oil than conventionally.

[0040] [Configuration of the present invention] [Configuration 1] a first gear and a second gear that mesh with each other; a rectifying block disposed on a disengaged side of the first gear and the second gear, the rectifying block generating negative pressure between the first gear and the second gear; an oil supply means for supplying oil between at least one of the first gear and the second gear and the rectifying block; A gear lubrication device comprising: [Configuration 2] The gear lubrication device according to configuration 1, A gear lubrication device, characterized in that the rectifying block has a length equal to or greater than the tooth tip pitch length along the circumferential direction of the first gear and the second gear. [Configuration 3] The gear lubrication device according to the first or second aspect, A gear lubrication device, characterized in that a gap between at least one of the first gear and the second gear and the straightening block is 0.5 mm or more and 2 mm or less. [Configuration 4] The gear lubrication device according to any one of configurations 1 to 3, A gear lubrication device, wherein the first gear and the second gear are helical gears. [Configuration 5] The gear lubrication device according to any one of configurations 1 to 4, A gear lubrication device comprising: a second oil supply means for supplying oil to the first gear and the second gear at the meshing start side. [Configuration 6] A gear lubrication method comprising: generating negative pressure between at least one of a first gear and a second gear and a rectifying block disposed on the disengagement side of the first gear and the second gear that are meshed with each other, and supplying oil between the rectifying block and at least one of the first gear and the second gear. [Explanation of symbols]

[0041] 10 Motor 12 Drive shaft 14 First stage gear mechanism 14a Drive gear 14b Driven gear 16 Transmission shaft 18 Second stage gear mechanism 18a Drive gear 18b Driven gear 20 Axle 22 Tire 24 Oil pump 26 Oil supply piping 30 Rectifying block 32 Oil supply means 32a Nozzle 100 Drive unit 200 Lubrication device.

Claims

1. a first gear and a second gear that mesh with each other; a rectifying block disposed on a disengaged side of the first gear and the second gear, the rectifying block generating negative pressure between the first gear and the second gear; an oil supply means for supplying oil between at least one of the first gear and the second gear and the rectifying block; A gear lubrication device comprising:

2. 2. The gear lubrication device according to claim 1, 10. A gear lubrication device, comprising: a lubricating block having a length equal to or greater than a tooth tip pitch length along a circumferential direction of the first gear and the second gear;

3. 3. The gear lubrication device according to claim 1 or 2, A gear lubrication device, characterized in that a gap between at least one of the first gear and the second gear and the straightening block is 0.5 mm or more and 2 mm or less.

4. 3. The gear lubrication device according to claim 1 or 2, 10. A gear lubrication device, wherein the first gear and the second gear are helical gears.

5. 3. The gear lubrication device according to claim 1 or 2, A gear lubrication device comprising: a second oil supply means for supplying oil to the first gear and the second gear at a position where they begin to mesh.

6. A gear lubrication method comprising: generating negative pressure between at least one of a first gear and a second gear and a rectifying block disposed on the disengagement side of the first gear and the second gear that are meshed with each other, and supplying oil between the rectifying block and at least one of the first gear and the second gear.

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