JP2017155788A - Power transmission unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power transmission unit which can suppress the blow-out of oil from a breather while suppressing an increase of a cost.SOLUTION: A breather chamber 14B is formed at an upper part of an insertion part 12. The breather chamber 14B communicates with the outside of a unit case 4 via a breather 5 which is attached to the unit case 4. The breather chamber 14B communicates with a space 22 which is sandwiched between two pieces of bearings 21 between a drive pinion shaft 2 and an internal peripheral face of the insertion part 12 via a second communication route 24 which is formed at the insertion part 12. Therefore, oil which intrudes into the breather chamber 14B can be discharged to the space 22 through the second communication route 24.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power transmission unit such as a transmission or a differential gear that transmits power from a drive source.

  In vehicles such as automobiles, power from a drive source is input to a transmission (transmission), and power shifted by the transmission is transmitted to drive wheels via a differential gear (differential device) or the like.

  FIG. 3 is a cross-sectional view showing a configuration in the vicinity of the drive pinion shaft 101 for inputting power to the differential gear.

  The drive pinion shaft 101 is accommodated in the unit case 102. A drive pinion gear made of, for example, a bevel gear is provided at an end portion of the drive pinion shaft 101 on the differential gear side, and the drive pinion gear meshes with a ring gear of the differential gear. Thereby, when the drive pinion shaft 101 rotates, the rotation is transmitted from the drive pinion gear to the ring gear, and the differential case of the differential gear rotates together with the ring gear. The rotation of the differential case is transmitted to the drive wheels via the drive shaft.

  In the unit case 102, oil (lubricating oil) for lubricating each part is enclosed. The rotation of the rotating body such as the drive pinion shaft 101, the ring gear, and the differential case stirs the oil, the oil temperature (oil temperature) rises, and the internal pressure of the unit case 102 rises accordingly. Therefore, a breather 103 for releasing the pressure in the unit case 102 to the atmosphere is provided on the upper part of the unit case 102.

  The unit case 102 is formed with an outer wall portion 104 that forms the outer shape of the unit case 102, and a plurality of partition wall portions 105 that extend radially from the outer wall portion 104 toward the drive pinion shaft 101. The inlet 106 of the breather 103 faces one of the spaces 107 located above the drive pinion shaft 101 in the space 107 sandwiched between the partition walls 105.

  When the foamed oil reaches the breather 103, the bubbles in the oil naturally disappear in the breather 103. The air separated from the oil is discharged from the breather 103 to the outside, and the oil returns from the breather 103 into the unit case 102. Thereby, the amount of bubbles in the oil can be suppressed.

JP-A-9-273621 JP 2006-38061 A

  However, if the unit case 102 is small, the oil level of the oil stored in the unit case 102 and the position of the breather 103 are close to each other. When the speed is increased, the oil may be ejected from the breather 103 to the outside.

  In order to prevent the ejection of oil from the breather 103, for example, a configuration in which the sheet metal member 108 is attached to the unit case 102 with the bolt 109 so as to close the space 107 to which the breather 103 is connected from the axial direction is conceivable. However, the addition of the sheet metal member 108 and the bolt 109 increases the number of parts and the manufacturing process, thereby increasing the cost.

  The objective of this invention is providing the power transmission unit which can suppress the ejection of the oil from a breather, suppressing the increase in cost.

  In order to achieve the above object, a power transmission unit according to the present invention is attached to a unit case, a rotating body accommodated in the unit case, two bearings that rotatably hold the rotating body, and the unit case. A breather for releasing the pressure in the unit case to the atmosphere, and the unit case has an insertion part through which the rotating body is inserted, and a plurality of partition wall parts extending in the rotation radial direction from the insertion part. The two bearings are interposed between the rotating body and the insertion portion, and are spaced apart from each other in the rotation axis direction of the rotating body, and above the insertion portion, by two partition wall portions adjacent to each other, A breather chamber is formed that communicates with the outside of the unit case via the breather, and a communication path is formed in the insertion portion that communicates the space between the rotating body and the insertion portion between the two bearings and the breather chamber. The To have.

  According to this configuration, the rotating body is inserted into the insertion portion and is rotatably held by the two bearings interposed between the rotating body and the inner peripheral surface of the insertion portion. A space sandwiched between two bearings is formed between the rotating body and the inner peripheral surface of the insertion portion. In addition, a breather chamber is formed above the insertion portion by two partition walls adjacent to each other. The breather chamber communicates with the outside of the unit case via a breather attached to the unit case. The breather chamber communicates with a space sandwiched between the two bearings between the rotating body and the insertion portion via a communication path formed in the insertion portion. Therefore, the oil that has entered the breather chamber can be discharged through the communication path to the space between the two bearings. As a result, the amount of oil in the breather chamber can be reduced, and the ejection of oil from the breather can be suppressed.

  Therefore, compared with the conventional configuration (configuration in which the sheet metal member 108 and the bolt 109 shown in FIG. 3 are provided), it is possible to suppress an increase in cost and to suppress the ejection of oil from the breather.

  Also, oil flowing into the space between the two bearings can be supplied to the two bearings. Therefore, the two bearings can be lubricated with oil, and the occurrence of seizure due to insufficient lubrication of the two bearings can be suppressed. As a result, the amount of oil in the unit case can be reduced, and the rotational resistance (stirring resistance) received by the member that rotates as the rotating body rotates can be reduced. By reducing the stirring resistance, the mechanical loss in the power transmission unit is reduced, and the traveling fuel consumption of the vehicle equipped with the power transmission unit can be improved.

  Each of the bearings is preferably a tapered roller bearing having a roller (roller) that is inclined away from the rotation axis of the rotating body as it goes outward with respect to the space.

  In this configuration, when the rotating body rotates, a negative pressure is generated in the space between the two bearings, and the negative pressure causes the oil in the breather chamber to be sucked into the space between the two bearings through the communication path. Therefore, oil can be actively flowed into the space between the two bearings. As a result, the ejection of oil from the breather can be suppressed more satisfactorily, and the two bearings can be better lubricated with oil.

  According to the present invention, it is possible to suppress the ejection of oil from the breather while suppressing an increase in cost as compared with the conventional configuration.

It is sectional drawing which shows the structure of the power transmission unit which concerns on one Embodiment of this invention. It is the figure which looked at the power transmission unit from the one side of the rotating shaft direction. It is sectional drawing which shows the structure of the conventional power transmission unit.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Configuration of power transmission unit>
FIG. 1 is a cross-sectional view showing a configuration of a power transmission unit 1 according to an embodiment of the present invention. FIG. 2 is a view of the power transmission unit 1 viewed from one side (power input side) in the rotation axis direction.

  The power transmission unit 1 includes a drive pinion shaft 2 and a differential gear Assy 3 and is a unit for transmitting power output from a transmission (not shown) to a drive shaft (not shown).

  The drive pinion shaft 2 and the differential gear Assy 3 are accommodated in the unit case 4. The unit case 4 is, for example, an aluminum casting that is cast by die casting. The unit case 4 includes an outer wall portion 11 that forms an outer shell of the power transmission unit 1, a cylindrical insertion portion 12 that is located inside the outer wall portion 11 and can be inserted through the drive pinion shaft 2, and the outer wall portion 11. A plurality of partition wall portions 13 extending between the portion 12 and extending radially around the insertion portion 12 are formed. Thereby, between the outer wall part 11 and the insertion part 12 is divided by the partition wall part 13, and between the outer wall part 11 and the insertion part 12, as shown in FIG. The same number of spaces 14 are formed around the insertion portion 12.

  Two spaces 14 </ b> A and 14 </ b> B of the plurality of spaces 14 are located above the insertion portion 12. The spaces 14A and 14B are adjacent to each other with the partition wall 13 interposed therebetween, and one space 14A is located upstream of the other space 14B in the rotational direction of the drive pinion shaft 2.

  The drive pinion shaft 2 is inserted through the insertion portion 12. As shown in FIG. 1, two bearings 21 are interposed between the drive pinion shaft 2 and the inner peripheral surface of the insertion portion 12. The two bearings 21 are arranged at an interval in the rotation axis direction of the drive pinion shaft 2. Thus, a space 22 sandwiched between the two bearings 21 is formed between the drive pinion shaft 2 and the inner peripheral surface of the insertion portion 12.

  A first communication passage 23 that communicates the space 14 </ b> A and the space 22 is formed in the insertion portion 12 so as to penetrate in the rotational radial direction. Further, the insertion portion 12 is formed with a second communication passage 24 that communicates the space 14B and the space 22 so as to penetrate in the rotational radial direction.

  As the bearing 21, a tapered roller bearing (tapered roller bearing) is employed. The inner race 25 of the bearing 21 is externally fitted to the drive pinion shaft 2 and is fixed to the drive pinion shaft 2. The outer race 26 of the bearing 21 is fitted into the insertion portion 12 and is fixed to the insertion portion 12. A plurality of rollers (conical rollers) 27 are interposed between the inner race 25 and the outer race 26, and the bearings 21 move away from the rotation axis of the drive pinion shaft 2 toward the outside of the space 22. It is provided in the direction which inclines. Further, spacers 28 are interposed between the inner races 25 of the two bearings 21, and the spacers 28 are fixed to the inner races 25.

  A first flange member 31 is fitted on the end of the drive pinion shaft 2 on the transmission side and is spline-fitted. The first flange member 31 is integrally formed with an outer fitting portion 32 that is fitted on the drive pinion shaft 2 and a flange portion 33 that protrudes outwardly from the transmission-side end portion of the outer fitting portion 32. Has been. The outer fitting portion 32 of the first flange member 31 is fitted on the drive pinion shaft 2, and the nut 34 is screwed onto the drive pinion shaft 2 protruding from the outer fitting portion 32, whereby the first flange member 31 is driven. The pinion shaft 2 is fixedly attached.

  A second flange member 35 is provided on the transmission side with respect to the first flange member 31. The second flange member 35 is attached to a rotary shaft 36 that is rotated by the power output from the transmission, and has a cylindrical portion 37 and a cylindrical portion 37 on the first flange member 31 side. And a flange portion 38 projecting in a shape. The flange portion 38 is in surface contact with the flange portion 33 of the first flange member 31. The flange portions 33 and 38 are fixed to each other by a bolt 39 that passes through them.

  A drive pinion gear 41 formed of a bevel gear is provided at the end of the drive pinion shaft 2 on the differential gear Assy3 side. The drive pinion gear 41 is disposed at a position above the center of the differential case 51 described below, and the drive pinion shaft 2 is offset upward with respect to a straight line extending in the axial direction of the drive pinion shaft 2 through the center of the differential case 51. It is arranged at the position.

  The differential gear Assy 3 includes a differential case 51. The differential case 51 is held in the unit case 4 so as to be rotatable about a rotation axis perpendicular to the rotation axis direction of the drive pinion shaft 2. The differential case 51 is formed with a flange portion 52 that projects radially from the outer periphery thereof. The flange portion 52 is provided with a ring gear (not shown) formed of a bevel gear so as not to be relatively rotatable. The drive pinion gear 41 is engaged with the ring gear.

  A breather 5 for releasing the pressure in the unit case 4 to the atmosphere is provided on the upper part of the unit case 4. As shown in FIG. 2, the breather 5 is inserted from the outside of the unit case 4 into a through hole 61 that penetrates the outer wall portion 11 of the unit case 4. The breather 5 communicates a breather chamber (hereinafter, referred to as “breather chamber 14 </ b> B”) formed of a space 14 </ b> B between the outer wall portion 11 and the insertion portion 12 and the outside of the unit case 4.

  The unit case 4 contains oil (lubricating oil) for lubricating each part. An oil reservoir is generated at the bottom of the unit case 4. For example, when the drive pinion shaft 2 is stationary, the oil amount in the unit case 4 is provided, for example, at the position where the oil level of the oil reservoir is indicated by a two-dot chain line in FIGS. 1 and 2, that is, the differential gear Assy 3. The differential side gear (not shown) is set so as to be positioned at substantially the same height as the lower end.

<Effect>
According to the above configuration, when the rotating shaft 36 is rotated by the power output from the transmission, the rotation is transmitted to the drive pinion shaft 2 via the first flange member 31 and the second flange member 35. The drive pinion shaft 2 rotates. When the drive pinion shaft 2 rotates, the rotation is transmitted from the drive pinion gear 41 to the ring gear, and the differential case 51 of the differential gear Assy3 rotates integrally with the ring gear. The rotation of the differential case 51 is transmitted to the drive shaft via a differential pinion shaft, a differential pinion gear, and a differential side gear (all not shown) provided in the differential gear Assy3. As a result, the power output from the transmission is transmitted to the drive shaft, and the power is transmitted from the drive shaft to the drive wheels of the vehicle on which the power transmission unit 1 is mounted.

  Oil is collected at the bottom of the unit case 4, and a part of the first flange member 31 and the second flange member 35 are immersed in the oil reservoir. Therefore, when the first flange member 31 and the second flange member 35 rotate with the rotation of the drive pinion shaft 2, the first flange member 31 and the second flange member 35 accumulate at the bottom of the unit case 4. Oil is raked up.

  The scooped up oil jumps into the space 14 </ b> A between the outer wall portion 11 and the insertion portion 12. This space 14A functions as an oil receiving chamber (hereinafter referred to as “oil receiving chamber 14A”) that receives oil scooped up from the bottom of the unit case 4, and the oil that has entered the oil receiving chamber 14A 14A is stored.

  The oil receiving chamber 14 </ b> A communicates with the space 22 sandwiched between the two bearings 21 between the drive pinion shaft 2 and the inner peripheral surface of the insertion portion 12 via the first communication passage 23 that penetrates the insertion portion 12. ing. Therefore, the oil accumulated in the oil receiving chamber 14 </ b> A flows into the space 22 between the drive pinion shaft 2 and the inner peripheral surface of the insertion portion 12 through the first communication path 23, and the space 22 rotates the drive pinion shaft 2. It is supplied to two bearings 21 sandwiched from both sides in the axial direction.

  Therefore, the two bearings 21 can be lubricated with oil without immersing the bearings 21 in oil, and the occurrence of seizure due to insufficient lubrication of the two bearings 21 can be suppressed. As a result, the amount of oil in the unit case 4 can be reduced, and the first flange member 31 and the second flange member 35 that rotate with the rotation of the drive pinion shaft 2 and other members (such as the differential case 51) The rotational resistance (stirring resistance) received from oil can be reduced. By reducing the stirring resistance, the mechanical loss in the power transmission unit 1 is reduced, and the traveling fuel consumption of the vehicle on which the power transmission unit 1 is mounted can be improved.

  The bearing 21 is a taper roller bearing, and the roller 27 is inclined so as to move away from the rotation axis of the drive pinion shaft 2 toward the outside with respect to the space 22 between the drive pinion shaft 2 and the inner peripheral surface of the insertion portion 12. It is provided in the direction to do. Thereby, as the drive pinion shaft 2 rotates, oil and air are discharged from the space 22 sandwiched between the two bearings 21 between the inner race 25 and the outer race 26 of the bearing 21 by the action of centrifugal force. A negative pressure can be generated in the space 22. Due to this negative pressure, the oil received in the oil receiving chamber 14 </ b> A is sucked into the space 22 sandwiched between the two bearings 21 through the first communication passage 23. Therefore, oil can be made to actively flow into the space 22 sandwiched between the two bearings 21, and the introduced oil can be supplied to the two bearings 21. Therefore, the two bearings 21 can be further lubricated with oil, and the occurrence of seizure due to insufficient lubrication of the two bearings 21 can be further suppressed.

  Further, a breather chamber 14B is formed above the insertion portion 12. The breather chamber 14 </ b> B communicates with the outside of the unit case 4 via a breather 5 attached to the unit case 4. Further, the breather chamber 14B has a space 22 sandwiched between the two bearings 21 between the drive pinion shaft 2 and the inner peripheral surface of the insertion portion 12 via the second communication path 24 formed in the insertion portion 12. Communicate. Therefore, the oil that has entered the breather chamber 14 </ b> B can be discharged to the space 22 through the second communication path 24. As a result, the amount of oil in the breather chamber 14B can be reduced, and the ejection of oil from the breather 5 can be suppressed.

  Further, since oil is also supplied to the space 22 from the breather chamber 14B, the two bearings 21 can be made to be in a better lubrication state by the oil, and the occurrence of seizure due to insufficient lubrication of the two bearings 21 is further increased. Can be suppressed.

<Modification>
As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form.

  For example, the drive pinion shaft 2 may be an output shaft of a transmission, or may be a transfer rotating shaft to which power from the output shaft is transmitted.

  In addition, various design changes can be made to the above-described configuration within the scope of the matters described in the claims.

1 Power transmission unit 2 Drive pinion shaft (rotating body)
4 Unit case 5 Breather 12 Insertion section 13 Partition wall section 14B Breather chamber 21 Bearing 22 Space 24 Second communication path (communication path)

Claims (1)

Unit case,
A rotating body housed in the unit case;
Two bearings for rotatably holding the rotating body;
A breather attached to the unit case for releasing the pressure in the unit case to the atmosphere;
The unit case has an insertion part through which the rotating body is inserted, and a plurality of partition wall parts extending in the rotational radial direction from the insertion part,
The two bearings are interposed between the rotating body and the insertion portion, and are spaced apart from each other in the rotation axis direction of the rotating body,
Above the insertion portion, a breather chamber communicating with the outside of the unit case via the breather is formed by two partition wall portions adjacent to each other.
The power transmission unit, wherein the insertion portion is formed with a communication path that connects the space between the two bearings and the breather chamber between the rotating body and the insertion portion.

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