Transaxle lubrication system

Abstract

To provide a lubrication device of a trans-axle which can inhibit reduction of oil.SOLUTION: A lubrication device of a trans-axle includes: a gear which transmits power of a motor; an output shaft which is connected at one end to the gear and outputs power of the gear; a case which houses the gear; a first oil stored in the case; a first seal part disposed between the case and the output shaft; a second seal part disposed at a position located between the case and the output shaft and spaced apart from the gear farther than the first seal part; and a second oil stored in a spaced enclosed by the first seal part, the second seal part, and the case.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a lubrication system for a transaxle. [Background technology]

[0002] Vehicle gears and other sliding parts need to be lubricated and cooled with oil to prevent wear caused by heat. If this oil evaporates and decreases, the gears and other parts will wear out, so there is a need for technology to prevent oil loss.

[0003] Patent Document 1 discloses a lubrication device that can prevent a decrease in the amount of lubricating oil supplied to areas that require lubrication. As in Patent Document 1, it is conceivable to supply oil stored in other areas to areas where oil has decreased. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-24072 Summary of the Invention [Problem to be solved by the invention]

[0005] However, supplying oil as in Patent Document 1 requires that extra oil be loaded onto the vehicle in advance, which is undesirable because it increases the weight of the vehicle.

[0006] The present disclosure has been made in view of the above, and aims to provide a lubrication device for a transaxle that can suppress oil loss. [Means for solving the problem]

[0007] The transaxle lubrication device of the present disclosure comprises a gear that transmits the power of a motor, an output shaft having one end connected to the gear and outputting the power of the gear, a case that houses the gear, a first oil stored in the case, a first seal portion arranged between the case and the output shaft, a second seal portion arranged between the case and the output shaft and at a position farther away from the gear than the first seal portion, and a second oil stored in a space surrounded by the first seal portion, the second seal portion, and the case. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to realize a transaxle lubrication device that can suppress oil loss. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a side view of a rover equipped with a TA unit according to an embodiment. [Figure 2] FIG. 2 is an enlarged view of the TA unit. [Figure 3] FIG. 3 is a cross-sectional view of the TA unit. [Figure 4] FIG. 4 is a cross-sectional view of a TA unit according to the first modification. DETAILED DESCRIPTION OF THE INVENTION

[0010] A lubrication device for a transaxle according to an embodiment of the present disclosure will be described with reference to the drawings. Note that the components in the following embodiments include those that are easily replaceable by those skilled in the art, or those that are substantially identical.

[0011] [Outline of the Rover] FIG. 1 is a side view of a rover equipped with a TA unit according to an embodiment. The rover 1 shown in FIG. 1 is equipped with multiple TA (transaxle) units 2 that transmit the power of multiple motors to tires, respectively. The rover 1 is capable of operating in an extremely high vacuum environment, such as on the surface of the moon. The TA units 2 function as a transaxle lubricating device. The rover 1 can move left and right in FIG. 1 by driving each of the multiple motors.

[0012] [TA unit configuration] Fig. 2 is an enlarged view of the TA unit. Fig. 3 is a cross-sectional view of the TA unit. Fig. 3 corresponds to the cross section taken along line AA in Fig. 2. As shown in Fig. 3, the TA unit 2 includes a gear 3, a case 4, a first oil 5, an output shaft 6, a first seal portion 7, a second seal portion 8, a second oil 9, and a bellows 10.

[0013] Gear 3 transmits the power of the motor.

[0014] The case 4 accommodates the gear 3 and stores the first oil 5 .

[0015] The first oil 5 is stored in the case 4 and lubricates and cools the gear 3. The first oil 5 may be an oil with a lower viscosity than the second oil 9. In addition, an additive may be added to the first oil 5 to prevent wear of the gear 3 and the like.

[0016] One end of the output shaft 6 is connected to the gear 3 and outputs the power of the gear 3 to the outside of the case 4.

[0017] The first seal portion 7 is disposed between the case 4 and the output shaft 6. The first seal portion 7 is a lip seal, but may also be a mechanical seal. The lip seal is made of, for example, a rubber-based or resin-based material.

[0018] The second seal portion 8 is disposed between the case 4 and the output shaft 6, at a position farther away from the gear 3 than the first seal portion 7. The second seal portion 8 may be a mechanical seal, but may also be a lip seal. The second seal portion 8 has a rotating ring 81 that rotates together with the output shaft 6, and a fixed ring 82 that is fixed to the case 4. A sliding surface 81a is formed between the rotating ring 81 and the fixed ring 82.

[0019] The second oil 9 is stored in a space surrounded by the first seal portion 7, the second seal portion 8, and the case 4. The second oil 9 lubricates and cools the sliding portion between the case 4 and the output shaft 6 and the sliding surface 81a. The second oil 9 may be an oil with a lower vapor pressure than the first oil 5. The second oil 9 may also be a special space oil that does not volatilize easily in a vacuum, or an ionic liquid.

[0020] The bellows 10 presses the fixed ring 82 toward the rotary ring 81 side.

[0021] [TA unit functions] In the TA unit 2, the first oil 5 only partially submerges the sliding portion between the case 4 and the output shaft 6, but the second oil 9 submerges the entire sliding portion between the case 4 and the output shaft 6, thereby preventing the first oil 5 and its additives from volatilizing and being reduced from between the case 4 and the output shaft 6.

[0022] Furthermore, since oils and additives tend to volatilize easily in an extremely high vacuum such as on the surface of the moon or at high altitudes where atmospheric pressure is low on Earth, volatilization of the second oil 9 can be suppressed by using an oil with a lower vapor pressure than the first oil 5 for the second oil 9. Furthermore, volatilization of the second oil 9 can be suppressed by using a special space oil that does not volatilize easily in a vacuum or an ionic liquid for the second oil 9.

[0023] Furthermore, by suppressing the evaporation of the first oil 5 by the second oil 9, the first oil 5 can be made to have a lower viscosity than the second oil 9, and the drive loss of the gear 3 can be reduced.

[0024] Furthermore, when the TA unit 2 is used on the ground, by using a low-volatility oil as the second oil 9 and suppressing the evaporation of the first oil 5, it is possible to use an extremely low-viscosity oil as the first oil 5, which is normally too volatile to be used, and this further reduces the drive loss of the gear 3.

[0025] In addition, the TA unit 2 has high durability because the second seal portion 8 is a mechanical seal that can be easily designed to suit the oil and usage conditions. Furthermore, the TA unit 2 has a lightweight and compact structure because the first seal portion 7 is a lip seal.

[0026] Furthermore, since the TA unit 2 is not configured to forcibly supply oil using an oil pump when oil levels decrease, the forced oil supply function will not be lost due to freezing or other reasons, resulting in the vehicle becoming unable to travel, even in extremely low-temperature environments such as the lunar surface.

[0027] In contrast, in conventional TA units, the oil only partially submerges the sliding portion between the case and the output shaft, so the oil evaporates from the portion of the sliding portion between the case and the output shaft that is not submerged, resulting in a loss of oil.In particular, in an extreme vacuum such as on the moon, the volatilized oil is released into the vacuum, making it extremely easy for the oil to be lost.

[0028] In addition, in conventional TA units, the entire sliding part between the case and the output shaft can be submerged in oil, but this increases the weight of the oil stored in the case. For a rover to be used on the lunar surface, increasing the weight of the oil is undesirable, as an increase in the weight at the time of launch is undesirable. Furthermore, if the entire sliding part between the case and the output shaft is submerged in oil, most of the gears will be submerged, increasing the drive loss of the gears and shortening the rover's travel distance.

[0029] (Variation 1) Fig. 4 is a cross-sectional view of a TA unit according to Modification 1. As shown in Fig. 4, in the TA unit 2A, the second seal portion 8A is a lip seal. By using lip seals for the first seal portion 7 and the second seal portion 8A in this way, the TA unit 2A may have an even lighter and more compact structure.

[0030] Further advantages and modifications will readily occur to those skilled in the art. Thus, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0031] 1 Rover 2, 2A TA unit 3 Gear 4 cases 5. First Oil 6 Output shaft 7 First seal part 8, 8A Second seal part 9. Second Oil 10 Bellows 81 Rotating Ring 81a sliding surface 82 Fixed ring

Claims

1. a gear that transmits power from the motor; an output shaft having one end connected to the gear and outputting the power of the gear; a case that houses the gear; a first oil stored in the case; a first seal portion disposed between the case and the output shaft; a second seal portion disposed between the case and the output shaft and at a position farther from the gear than the first seal portion; a second oil stored in a space surrounded by the first seal portion, the second seal portion, and the case, the second oil having a lower vapor pressure than the first oil; A transaxle lubrication device comprising:

2. 2. The transaxle lubrication device according to claim 1, wherein the first oil has a lower viscosity than the second oil.

3. 2. The transaxle lubrication device according to claim 1, wherein the second oil is oil that does not easily volatilize in a vacuum.

4. the first seal portion is a lip seal, 2. The transaxle lubrication device according to claim 1, wherein the second seal portion is a mechanical seal.

Images