Gear lubrication device and gear lubrication method

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 lubricating device for gears and a method for lubricating gears.

Background Art

[0002] As a method for lubricating gears used in a drive system of a vehicle such as an electric vehicle or a hybrid vehicle, a splash (oil bath) lubrication method or a forced lubrication method is used. The forced lubrication method includes methods such as a drip type, a jet type (oil jet type), and a spray type (oil air type). The jet type (oil jet type) is often applied to the gear directly connected to the motor shaft having the highest rotational speed.

[0003] As the transmission torque between gears increases, the frictional loss on the tooth surface increases and the tooth surface temperature rises. On the other hand, increasing the oil supply amount to the gears increases the cooling capacity and the tooth surface temperature decreases. However, regarding the tooth surface temperature with respect to the oil supply amount, it is known that in the region where the oil supply amount is 1.2 L / min or more, it is difficult to improve the cooling effect only by increasing the oil supply amount.

[0004] Further, as an example of improving the lubrication of high-speed gears, a lubricating device is disclosed in which a turbulent flow on the outer periphery of the gear is suppressed by a rectifying block (shroud) having a minute gap disposed outside the tip surface of the gear teeth, and an oil mist easily reaches the tooth surface (Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Incidentally, when gears used in a drive system rotate at high speeds, it is desirable to achieve good cooling and lubrication conditions with a small amount of oil. Motors used in vehicles such as electric vehicles are becoming faster (for example, around 17,000 rpm) in order to miniaturize the entire drive unit. The peripheral speed of the tooth tip of a gear directly connected to the motor is determined by the rotational speed of the motor, and for a gear with a tooth tip diameter of Φ50 mm, it can reach as high as 44.5 m / s at a high rotational speed of 17,000 rpm.

[0007] On the other hand, as the peripheral speed of the gears increases, mechanical losses during oil agitation increase, so it is desirable to reduce the amount of oil supplied to the gears. However, if the cooling of the tooth surface is insufficient, the tooth surface temperature may rise, potentially leading to tooth surface damage such as scouring, and currently, an excessive amount of oil is supplied. [Means for solving the problem]

[0008] One aspect of the present invention is a gear lubrication device characterized by comprising: a first gear and a second gear that mesh with each other; a flow straightening block disposed on the disengagement side of the first gear and the second gear and generating a negative pressure between the first gear and at least one of the second gear; and an oil supply means for supplying oil between the first gear and at least one of the second gear and the flow straightening block.

[0009] In this case, it is preferable that the rectifier 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] Furthermore, it is preferable that the gap between at least one of the first gear and the second gear and the rectifier block be 0.5 mm or more and 2 mm or less.

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

[0012] Furthermore, it is preferable to provide a second oil supply means for supplying oil at the beginning of meshing between the first gear and the second gear.

[0013] Another aspect of the present invention is a gear lubrication method characterized by supplying oil between at least one of the first gear and the second gear and the rectifier block, while a negative pressure is generated between at least one of the first gear and the second gear and the rectifier block, which is positioned on the disengaged side of the first gear and the second gear that mesh with each other. [Effects of the Invention]

[0014] According to the present invention, good cooling and lubrication can be achieved for high-speed rotating gears with a smaller supply of lubricating oil than in conventional methods. [Brief explanation of the drawing]

[0015] [Figure 1] This figure shows an example of the configuration of a vehicle drive unit according to an embodiment of the present invention. [Figure 2] This figure shows the configuration of a gear lubrication device in an embodiment of the present invention. [Figure 3] This figure shows a specific configuration of a gear lubrication device according to an embodiment of the present invention. [Modes for carrying out the invention]

[0016] Figure 1 shows an example configuration of a vehicle drive unit 100 to which the gear lubrication device of the present invention is applied. The vehicle drive unit 100 comprises 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] The drive shaft 12 is rotationally driven by the motor 10. The rotation of the drive shaft 12 is decelerated and transmitted from the drive gear 14a to the driven gear 14b by the first-stage gear mechanism 14. The driven gear 14b is fixed to the transmission shaft 16. The transmission shaft 16 is rotationally driven along with the rotation transmitted to the driven gear 14b. The rotation of the transmission shaft 16 is decelerated and transmitted from the drive gear 18a to the driven gear 18b by the second-stage gear mechanism 18. The driven gear 18b is fixed to the axle 20. The axle 20 is rotationally driven along with the rotation transmitted to the driven gear 18b. The axle 20 is fixed to the tire 22. The tire 22 rotates along with the rotation of the axle 20.

[0018] Also, the drive unit 100 of the vehicle 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] FIG. 2 shows the configuration of the gear lubrication device 200 in the embodiment of the present invention. The gear lubrication device 200 includes a rectifying block 30 and an oil supply means 32. The gear lubrication device 200 is used in combination with the drive gear 14a and the driven gear 14b of the first-stage gear mechanism 14 or the drive gear 18a and the driven gear 18b of the second-stage gear mechanism 18.

[0020] Hereinafter, the case where the gear lubrication device 200 is applied to the first-stage gear mechanism 14 will be described, but the case where it is applied to the second-stage gear mechanism 18 is the same.

[0021] The rectifying block 30 is arranged on the disengaged side of the meshing of the driving gear 14a and the driven gear 14b. The rectifying block 30 has a thickness in the direction along the rotation axes of the driving gear 14a and the driven gear 14b (the depth direction of the drawing). The rectifying block 30 is arranged in a state where a slight gap is secured so as not to contact the tooth tips along the outer peripheral direction of the tooth tips of the driving gear 14a and the driven gear 14b. The gap is preferably set such that the driving gear 14a or the driven gear 14b does not contact the rectifying block 30 and oil can be retained between the driving gear 14a or the driven gear 14b and the rectifying block 30 as described later. Further, the gap may be appropriately set according to the diameters of the driving gear 14a and the driven gear 14b, but for example, it is preferably 0.5 mm or more and 2 mm or less.

[0022] Here, the starting side of the gear meshing means the side of the region where the driving gear 14a and the driven gear 14b change from a non-meshing state to a meshing state as they rotate. Further, the disengaged side of the gear meshing means the side where the driving gear 14a and the driven gear 14b change from a meshing state to a non-meshing state as they 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 an oil supply pipe 26. Further, the oil supply means 32 includes a nozzle 32a. The nozzle 32a is directed toward the portion (disengaged region) where the meshing of the driving gear 14a and the driven gear 14b starts to disengage on the disengaged side of the meshing of the driving gear 14a and the driven gear 14b.

[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 disengaged region of the driving gear 14a and the driven gear 14b.

[0025] The operation of the gear lubrication device 200 in the embodiment of the present invention will be described below. Referring to Figure 2, the states (1) to (6) of the drive gear 14a and driven gear 14b will be described along the rotational direction.

[0026] State (1) is when the drive gear 14a and the driven gear 14b are completely disengaged (fully open). At this time, the pressure between the drive gear 14a and the driven gear 14b is the same as the external pressure (reference pressure). Subsequently, as rotation occurs, the teeth of the driven gear 14b enter the tooth grooves of the drive gear 14a, pushing out the air in the tooth grooves of both the drive gear 14a and the driven gear 14b, resulting in a semi-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 become a fully closed state (state (3)). Subsequently, the driven gear 14b begins to disengage from the drive gear 14a, resulting in a semi-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 gears disengage, a closed space is formed between the flow rectifier block 30 and the drive gear 14a, resulting in a fully open flow rectifier state (state (5)). At this time, the pressure between the drive gear 14a and the driven gear 14b becomes a slightly negative pressure, which is slightly lower than the external pressure (reference pressure). Finally, the teeth of the drive gear 14a disengage from the flow rectifier block 30, returning to the 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 level 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 attempt to disengage. Due to the pressure from the oil pump 24 and the action of this negative pressure, the oil supplied from the oil supply means 32 is efficiently filled into the tooth grooves of the drive gear 14a. The filled oil remains in the tooth grooves of the drive gear 14a by the rectifier block 30 until the fully open state (state (6)) is reached, ensuring sufficient cooling time for the tooth surface of the drive gear 14a. After that, when the fully open state (state (6)) is reached, the cooled oil is discharged by centrifugal force, completing the cooling process.

[0028] Here, the cooling time of the drive gear 14a by oil is determined by the length L1 of the gap between the drive gear 14a and the flow straightening block 30. That is, it is determined by the length L1 of the surface of the flow straightening block 30 along the circumferential direction of the drive gear 14a. It is preferable that the length L1 be greater than or equal to the pitch length P1 of the tooth tip of the drive gear 14a. This ensures that the area in which oil is retained in the tooth groove of the drive gear 14a is long enough for cooling, and the drive gear 14a can be sufficiently cooled by the oil.

[0029] When the drive gear 14a and the driven gear 14b disengage, the flow between the driven gear 14b and the flow straightening block 30 also becomes fully open. Subsequently, the teeth of the driven gear 14b disengage from the flow straightening 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 attempt to disengage. Due to the pressure from the oil pump 24 and the action of this negative pressure, the oil supplied from the oil supply means 32 is efficiently filled into the tooth grooves of the driven gear 14b. The filled oil remains in the tooth grooves of the driven gear 14b by the rectifier block 30 until the gear is fully open, ensuring sufficient cooling time for the tooth surfaces of the driven gear 14b. After that, when the gear is fully open, the cooled oil is discharged by centrifugal force, completing the cooling process.

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

[0032] Furthermore, the driven gear 14b has more teeth than the drive gear 14a, resulting in less work per tooth and a lower tooth surface temperature. Therefore, the gap between the driven gear 14b and the flow straightening block 30 can be increased, or the flow straightening block 30 can be omitted from the driven gear 14b side. This allows oil to be discharged earlier from the driven gear 14b side, reducing the resistance of the oil to the rotation of the driven gear 14b.

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

[0034] In this specific example, the oil supply means 32 is provided with multiple (6) nozzles 32a along the width W1 direction of the flow straightening block 30. This allows for effective oil supply along the tooth width direction of the drive gear 14a and driven gear 14b.

[0035] Furthermore, it is preferable that the width W1 of the flow straightening block 30 along the axial direction of the gear be greater than or equal to the tooth width W2 of the drive gear 14a and driven gear 14b along the axial direction. This improves the negative pressure generation effect on the drive gear 14a and driven gear 14b, enabling highly efficient oil retention.

[0036] Furthermore, by applying the gear lubrication device 200 to a helical gear having a helix angle θ, the oil supplied to position (a) is pushed aside by the helical tooth surface and sent along the axial direction of the gear from position (b) to position (c), and is also discharged from the ends of the drive gear 14a and driven gear 14b. This flow of oil over the tooth surface improves the cooling capacity of the tooth surface.

[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, a configuration has been described in which the flow straightening block 30 is placed on the gear disengagement side and no oil is supplied to the gear engagement side, but the invention is not limited to this configuration. A conventional oil jet system or the like may be used in combination as a second oil supply means on the gear engagement side. In this case, it is preferable to supply the minimum amount of oil necessary for lubrication from the gear engagement side and to activate the oil supply by the lubrication device 200 only when the tooth surface temperature is high. For example, when the gear rotation speed is low, oil may be supplied only to the gear engagement side, and as the rotation speed increases, the amount of oil supplied to the disengagement side by the lubrication device 200 may be increased. This enables more efficient lubrication and cooling of the tooth surface.

[0039] As described above, the gear lubrication device 200 in this embodiment makes it possible to achieve good cooling and lubrication of high-speed rotating gears with a smaller supply of lubricating oil than in conventional devices.

[0040] [Structure of the present invention] [Configuration 1] The first gear and the second gear, which mesh with each other, A flow rectifier block is positioned on the disengagement side of the first gear and the second gear, and generates a negative pressure between the first gear and at least one of the second gears, An oil supply means for supplying oil between at least one of the first gear and the second gear and the rectifier block, A gear lubrication device characterized by comprising the following: [Configuration 2] A gear lubrication device as described in Configuration 1, The gear lubrication device is characterized in that the flow straightening 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] A gear lubrication device as described in configuration 1 or 2, A gear lubrication device characterized in that the gap between at least one of the first gear and the second gear and the rectifier block is 0.5 mm or more and 2 mm or less. [Structure 4] A gear lubrication device according to any one of items 1 to 3, A gear lubrication device characterized in that the first gear and the second gear are helical gears. [Composition 5] A gear lubrication device according to any one of items 1 to 4, A gear lubrication device characterized by comprising a second oil supply means for supplying oil at the starting point of meshing between the first gear and the second gear. [Composition 6] A gear lubrication method characterized by supplying oil between at least one of the first gear and the second gear and the rectifier block, while a negative pressure is generated between at least one of the first gear and the second gear and the rectifier block, which is positioned on the disengaged side of the first gear and the second gear that mesh with each other. [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 Flow rectifier block 32 Oil supply means 32a Nozzle 100 Drive unit 200 Lubrication device.

Claims

1. The first gear and the second gear, which mesh with each other, A rectifier block is positioned on the disengagement side of the first gear and the second gear, and generates a negative pressure between at least one of the first gear and the second gear, An oil supply means that supplies oil from the rectifier block toward the disengagement region of the first gear and the second gear, Equipped with, A gear lubrication device characterized by supplying the oil to the tooth groove of the first gear or the tooth groove of the second gear by the action of the negative pressure.

2. A gear lubrication device according to claim 1, The gear lubrication device is characterized in that the flow straightening 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.

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

4. A gear lubrication device according to claim 1 or 2, A gear lubrication device characterized in that the first gear and the second gear are helical gears.

5. A gear lubrication device according to claim 1 or 2, A gear lubrication device characterized by comprising a second oil supply means for supplying oil at the beginning of meshing between the first gear and the second gear.

6. A gear lubrication method characterized by generating a negative pressure between at least one of the first gear and the second gear and the rectifier block, which is positioned on the disengagement side of the first gear and the second gear that mesh with each other, supplying oil from the rectifier block toward the disengagement region of the first gear and the second gear, and supplying the oil to the tooth groove of the first gear or the tooth groove of the second gear by the action of the negative pressure.

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