JPH11141652A - Power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use an air breather in common with a unit casing and a differential casing into smaller size, secure quick operablity and durability and prevent oil leakage. SOLUTION: This power transmission device has a unit casing 21, in which clutch units including a differential limiting clutch mechanism, an electromagnet 29 and a servo operating mechanism are stored, connected and fixed to the front end of a differential casing 12. An oil communication passage 65 to communicate oil in both casings 12, 21 is formed at the upper part of the differential casing 12, a drive pinion 11 is arranged to be offset downward and an air breather 85 is arranged in a recess 86 on the upper face side of the differential casing 12 and connected to the oil communication passage 65.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission device for a vehicle, and more particularly to a power transmission device in which a common air breather is provided in a differential casing and a unit casing, and the arrangement of the air breather is improved.

[0002]

2. Description of the Related Art Conventionally, an electromagnetic clutch may be applied as a clutch for intermittently connecting a power transmission system of a vehicle (Japanese Patent Laid-Open No. 4-39425, Japanese Utility Model Application Laid-Open No. 4-1381).
No. 33). In the device disclosed in Japanese Utility Model Laid-Open No. 4-138133, a clutch casing of an electromagnetic clutch is fixed to a front end of a differential casing of a rear differential gear device of a four-wheel drive vehicle, and the rear wheel drive system can be intermittently connected by the electromagnetic clutch. The electromagnet is arranged at the front end side inside the clutch casing, the wet multi-plate clutch is arranged at the rear part inside the clutch casing, oil flows through the inside of the differential casing and the inside of the clutch casing, and is repelled by gears. The oil is supplied to the inside of the clutch casing, and the oil lubricates the bearing of the electromagnetic clutch and cools the electromagnet.

On the other hand, recently, as a power transmission device used for a power transmission system of a vehicle, a power transmission device having a simple structure and a differential limiting function has been proposed (Japanese Patent Laid-Open No. 7-1214).
No. 4, JP-A-5-12767). In the power transmission device disclosed in Japanese Patent Application Laid-Open No. 7-12144, a unit casing is fixed to the front end of a differential casing of a rear differential gear device of a four-wheel drive vehicle in the same manner as the above-mentioned electromagnetic clutch. And a differential limiting clutch mechanism including a wet multi-plate clutch, a rotating blade and a clutch operating mechanism for operating the wet multi-plate clutch via a viscous fluid, and accommodates a difference in rotation speed between the front wheel and the rear wheel. The wet multi-plate clutch is automatically engaged by a clutch operating mechanism to transmit driving force to the rear wheels, thereby limiting the differential between the front wheels and the rear wheels.

The power transmission device described in Japanese Patent Application Laid-Open No. 5-12767 is provided at an intermediate portion of a propeller shaft that transmits driving force to rear wheels. In the unit casing, a differential limiting clutch mechanism including a wet multi-plate clutch, a rotating blade, and a clutch operating mechanism for operating the wet multi-plate clutch via a viscous fluid is housed in the unit casing. An electromagnet for fastening the differential limiting clutch mechanism is accommodated in the casing, and a controller and a control circuit for controlling the drive of the electromagnet are provided.

[0005] In this driving force transmission device, similarly to the above-described device, the wet multi-plate clutch is automatically engaged by the clutch operating mechanism in accordance with the rotational speed difference between the front wheel and the rear wheel, and the driving force is transmitted to the rear wheel. And a control signal from the controller excites the electromagnet via a control circuit, engages a differential limiting clutch mechanism, and transmits a driving force to the rear wheel drive system. Conventionally, in a device that incorporates a gear mechanism, a clutch mechanism, and the like in a casing and oil-lubricates those mechanisms, an air breather device for preventing gas pressure in the casing is connected to the casing. In this case, an air breather device is provided for each casing. Is generally provided.
However, Japanese Unexamined Utility Model Publication No. 57-38948 describes a technique in which a casing of a transmission of a vehicle or another casing is connected to an air breather device by piping, and the air breather device is shared.

[0006]

When each of the air breathers is provided on a plurality of casings, the number of air breather devices is increased, the overall structure is complicated, and the manufacturing cost is disadvantageous. On the other hand, the above-mentioned Japanese Utility Model Application
In the case of connecting to the air breather device by piping from a plurality of casings as in the device described in Japanese Patent Publication No. , Disadvantageous in terms of production cost. It is also conceivable to provide an air breather device in one of the two casings communicating with each other. There is a problem that it is not possible to quickly cope with the increase in gas pressure.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power transmission device in which a unit casing accommodating a clutch unit is fixed to a differential casing, to share the air breather device, improve the arrangement of the air breather device, and improve quick operability and durability. It is to secure.

[0008]

According to a first aspect of the present invention, there is provided a power transmission device in which a clutch unit is accommodated in a unit casing fixed to a differential casing accommodating a differential gear mechanism of a vehicle, and the clutch unit is lubricated with oil. In such a power transmission device, an air breather device is provided which forms an oil communication passage communicating between the inside of the differential casing and the inside of the unit casing, and is connected to the oil communication passage and prevents a rise in gas pressure in both casings. It is provided.

Since oil flows through the oil communication passage between the inside of the unit casing and the inside of the differential casing, the temperature of the oil is kept low as a whole, and the gas pressure in the unit casing does not easily rise. Become. In addition, since the air breather device is connected to the oil communication passage that connects the inside of the differential casing and the inside of the unit casing, the pressure rise can be reduced through a large volume in a plurality of casings as compared with the independent pressure rise in each casing. Can be smaller. Therefore, one relatively small air breather device can be shared between the unit casing and the differential casing, and the air breather device operates with good responsiveness both when the gas pressure inside the unit casing and when the gas pressure inside the differential casing rises.

A power transmission device according to a second aspect is characterized in that, in the first aspect of the invention, the clutch unit includes an electromagnet, and one end of the oil communication passage is opened toward the electromagnet. . The electromagnet is a heat source,
Although the gas pressure in the vicinity is easy to increase, one end of the oil communication passage to which the air breather device is connected is open toward the electromagnet, so that the gas pressure in the vicinity of the electromagnet can be effectively prevented from increasing, and Temperature rise can also be suppressed. Other operations are the same as those of the first aspect.

According to a third aspect of the present invention, in the power transmission device according to the first or second aspect, the drive pinion of the differential gear mechanism is disposed so as to be offset downward with respect to the axis of the differential gear mechanism. An air breather device is provided above the drive pinion.
Since the drive pinion is offset downward,
That much space can be secured above the drive pinion, and the air breather device can be arranged by effectively utilizing the space. Other operations are the same as those of the first or second aspect.

According to a fourth aspect of the present invention, in the power transmission apparatus according to the first or second aspect, the drive pinion of the differential gear mechanism is disposed so as to be offset downward with respect to the axis of the differential gear mechanism. A recess that is recessed downward is formed above the drive pinion on the upper surface side of the differential casing, and the air breather device is disposed in the depression and attached to the differential casing.

Since the drive pinion is offset downward in the same manner as in the third aspect, a downward recess can be formed above the drive pinion on the upper surface side of the differential casing. By utilizing the air breather device, it is possible to prevent muddy water from being sucked into the air breather device, and to install the air breather device in a differential casing that does not easily rise in temperature, so that oil leaks from the air breather device connection due to thermal expansion This is advantageous in terms of prevention. Other operations are the same as those of the first or second aspect.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. This embodiment is an example in which the present invention is applied to a driving force transmission device of a four-wheel drive vehicle. As shown in FIG. 1, a pair of left and right front wheels 1, an engine 2, The vehicle 3, a front differential 4, a pair of left and right front wheel axles 5, a transfer 6 and the like are provided. A pair of left and right rear wheels 7, a pair of right and left rear wheel axles 8, a rear wheel differential are provided at the rear of the vehicle. A rear differential 9 as a gear device, a power transmission device 20 fixedly connected to a front end of the rear differential 9 and the like are provided, and in response to a rotational speed difference between the front wheel 1 and the rear wheel 7 or in response to a command from a driver's seat or the like. Accordingly, the driving force is transmitted from the transfer 6 to the rear differential 9 via the propeller shaft 10 and the power transmission device 20.

Next, the power transmission device 20 will be described in detail (see FIGS. 2 to 6). This power transmission device 20
The unit casing 21, the input shaft 23 connected to the rear end of the propeller shaft 10 via a companion flange 22, the sleeve-shaped intermediate shaft 24 splined to the front end of the drive pinion 11 of the rear differential 9, and the intermediate shaft 24. Input shaft 2 fitted externally with an annular space
3, an outer case 25 bolted to 3, an end case 26 for closing a rear end opening of the outer case 25, a differential limiting clutch mechanism 27 for limiting the differential between the outer case 25 and the intermediate shaft 24, an electromagnet 29, an electromagnet 29. , And has a boosting operation mechanism 30 for engaging the differential limiting clutch mechanism 27 by a boosting action, and various structures described later. Note that a unit inside the unit casing 21 corresponds to a clutch unit.

Next, the unit casing 21 will be described (see FIGS. 2 and 3). Unit casing 2
Reference numeral 1 denotes a case member made of an aluminum alloy that covers the outside of the power transmission device 20. The case member has a substantially cylindrical tubular portion 21a whose diameter increases slightly toward the rear, and an annular front wall portion 21b integrated therewith.
A plurality of cooling fins 31 that are air-cooled by traveling wind are integrally formed on the outer surface of the unit casing 21, and the unit casing 21 is attached to the vehicle body at both left and right ends substantially at the center in the front-rear direction of the upper surface of the unit casing 21. 4 for
The two mounting portions 32 are formed, and the space between the mounting portions 32 in the vehicle width direction and the space in the front-rear direction are set sufficiently large, so that the mounting portions 32 can be stably mounted on the vehicle body.

An input shaft 23 and a tubular portion of a companion flange 22 screwed and fixed to the input shaft 23 are rotatably mounted on a front wall 21b of the unit casing 21 via a cover, an oil seal, and a bearing 33. It is fitted. As described later, the oil circulates and circulates between the inside of the differential casing 12 and the inside of the unit casing 21.

A connecting flange 34 is formed on the outer surface of the rear end of the unit casing 21, and a spigot fitting portion 35 is formed at the rear end of the unit casing 21 over the entire circumference. The part 35 is fitted inside the spigot fitting hole 13 at the front end of the cast iron differential casing 12 with a spigot, and the connecting flange 34 is connected to the rear end of the differential casing 12 with eight bolts 36 at eight equally circumferential positions. It is fixed to the connection flange 14. Therefore, although the coefficient of thermal expansion of the unit casing 21 made of an aluminum alloy is larger than the coefficient of thermal expansion of the differential casing 12 made of cast iron, even if the unit casing 21 is thermally expanded, the spigot inner fitting portion 36 and the spigot fitting hole are formed. 13 does not leak the internal oil.

Next, the intermediate shaft 24 and the drive pinion 11 will be described (see FIGS. 2 and 3). The sleeve portion 24a at the rear end of the intermediate shaft 24 is externally fitted to the spline shaft portion 11a of the drive pinion 11 by spline fitting, and the front end of the intermediate shaft 24 is connected to the front wall of the outer case 25 via a bearing 37. The intermediate shaft 24 is rotatably supported by the drive pinion 11 so as to rotate integrally with the drive pinion 11. The drive pinion 11 belongs to a rear wheel differential gear device, and the drive pinion 11 is disposed in a front-rear direction with a predetermined distance offset downward from an axis of the rear wheel differential gear device ( 3), the pinion 1 having hypoid gear teeth of the drive pinion 11
1b is meshed with a ring gear 15 having hypoid gear teeth of a differential gear mechanism.

An intermediate portion of the drive pinion 11 is formed by a pair of tapered bearings 40 and 41 to form the differential casing 1.
2 and rotatably supported by tapered bearings 40 and 4
A spacer 42 is provided between the two, and the inner race of the tapered bearing 40 is prevented from coming off by a nut member 43. The front tapered bearing 40 is a bearing whose outer diameter increases toward the front, and the rear taper bearing 41 is a bearing whose outer diameter increases toward the rear.

Next, the outer case 25 and the end case 26 will be described (see FIGS. 2 and 3). The outer case 25 includes a front wall portion 25b rotatably fitted to the intermediate shaft 24 and a cylindrical portion 25a integrally extending rearward from an outer peripheral portion of the front wall portion 25b. 26 is firmly screwed into the female screw hole 25c at the rear end of the cylindrical portion 25a and fixed. End case 26
Is a member that closes the opening on the rear end side of the outer case 25 and forms a magnetic path for the electromagnet 29, and is made of a magnetic material. The end case 26 is rotatable around the sleeve portion 24a on the rear end side of the intermediate shaft 24. Is fitted outside. In addition, seal members are respectively attached to the inner peripheral portion and the outer peripheral portion of the end case 26.

Next, the differential limiting clutch mechanism 27 will be described (see FIGS. 2 and 3). The differential limiting clutch mechanism 27 includes a wet type multi-plate clutch 44, a clutch operating mechanism 45 for operating the multi-plate clutch 44, and a clutch operating mechanism 45 disposed at a front end of the differential limiting clutch mechanism 27. Having. The multi-plate clutch 44 includes a plurality of clutch plates 46a engaged with spline teeth on the inner surface of the outer case 25 and a plurality of clutch plates 46b engaged with spline teeth on the outer surface of the intermediate shaft 24.
6a and a plurality of clutch plates 46b arranged alternately. When the multi-plate clutch 44 is pushed rearward by the piston member 47 of the clutch operating mechanism 45, the clutch is brought into the engaged state according to the pushing force, and the outer From the case 25 to the intermediate shaft 24
And vice versa, a torque corresponding to the pressing force is transmitted. When not pressed by the piston member 47, the multiple disc clutch 44 is not engaged. The storage chamber in which the multi-plate clutch 44 is stored is filled with oil.
However, a dry multi-plate clutch may be applied instead of the wet multi-plate clutch 44.

The clutch actuating mechanism 45 is attached to the intermediate shaft 24 so as to rotate integrally with the intermediate chamber 24 so as to rotate integrally with the stay chamber 50 having a circular section and formed in the rear end surface of the front wall 25 b of the outer case 25. It comprises a rotating blade 51 fitted and mounted in the retaining chamber 50, a piston member 47 for closing the rear end face of the retaining chamber 50, and a viscous fluid such as silicone oil sealed in the retaining chamber 50. There is almost no gap between the front and rear sides of the rotating blade 51 in the retaining chamber 50, and the rotating blade 51 has a plurality of blade portions (not shown) at a plurality of equally spaced positions in the circumferential direction.

The pressure of the viscous fluid between the blades in the retention chamber 50 is reduced by the outer case 25 and the intermediate shaft 24.
And the pressure of the viscous fluid acts on the piston member 47 to press the multi-plate clutch 44,
The multi-plate clutch 44 is engaged so as to transmit a torque corresponding to the rotational speed difference. Incidentally, sealing members 52, 53, 5 for sealing so that the viscous fluid does not leak from the retention chamber 50.
4 are provided.

Next, the electromagnet 29 and the booster 30 will be described (see FIGS. 2 and 3). The electromagnet 29 includes an annular coil 55 and an annular yoke 56 made of a magnetic material. The electromagnet 29 is disposed at an end (rear end) of the unit casing 21 on the differential casing 12 side.
Reference numeral 6 is internally fixed to an annular shelf 16 of the differential casing 12. The yoke 56 is rotatably supported by the end case 26 via a ball bear rig 57. An annular magnetic path blocking member 58 made of a non-magnetic material is fitted to a portion of the end case 26 on the front side of the coil 55. A magnetic path as shown by a chain line in FIG. 2 is formed via a lock cam member 61 made of a magnetic material of the boosting operation mechanism 30.

The front end of the end case 26 and the multi-plate clutch 4
4, a booster operating mechanism 30 is disposed. The booster operating mechanism 30 includes a lock cam member 61 rotatably fitted to the sleeve portion 24 a of the intermediate shaft 24 and the outer case 2.
5 has a lock plate 62 fitted inside so as to be relatively non-rotatable and movable in the axial direction, and a plurality of radially extending cam portions formed on these opposing surface portions. Each cam portion has a substantially triangular cross-section cam groove formed in the lock plate 62 and a lock cam member 6 engaged with the cam groove.
1 and a protruding ridge portion.

When the electromagnet 29 is excited, the lock cam member 61 is attracted and its rotation is restricted, and the lock plate 62 is rotated relative to the lock cam member 61, and the lock plate 62 is strongly moved forward by the action of the plurality of cam portions. And the multi-plate clutch 44 is switched to the engaged state. still,
The above-described boosting operation mechanism 30 is merely an example, and other various boosting operation mechanisms (for example, a boosting operation mechanism having a structure similar to a ball clutch mechanism) are applied instead of the boosting operation mechanism 30. You may. Further, by switching the excitation intensity of the electromagnet 29 to a plurality of levels, the degree of engagement of the multi-plate clutch 44 may be switched to a plurality of levels.

Next, a configuration for cooling and lubricating each part with oil will be described (see FIGS. 2 and 3). The interior of the differential casing 12 and the interior of the unit casing 21 are filled with oil to a predetermined level (substantially the level of the rear wheel axle), and the oil is circulated through the interior of the differential casing 12 and the interior of the unit casing 21. And distribute it.

An oil passage 64 communicating with the inside of the unit casing 21 is formed at the bottom of the differential casing 12, and the inside of the differential casing 12 and the unit casing 2 are formed at an upper wall on the front end side inside the differential casing 12.
An oil communication passage 65 that communicates with the inside of the fuel cell 1 is formed,
An annular oil passage 66 is formed between the tapered bearing 40 and the electromagnet 29, and an annular oil passage 67 is formed on the outer peripheral portion of the front end inside the differential casing 12, and the oil passages 66 and 67 are formed in a circumferential direction. Are connected to each other through communication passages 68 at appropriate intervals, and an annular oil passage 69 is formed outside the outer case 25. The rear end of the oil communication passage 65 opens toward the yoke 56 of the electromagnet 29.

The axis of each roller of the tapered bearing 49 is directed toward the yoke 56 and the bearing 57 of the electromagnet 29, and oil is provided below the tapered bearings 40 and 41. Since the outer diameter increases toward the front, the tapered bearing 4
Oil is injected toward the yoke 56 and the bearing 57 from the entire circumference of the cylinder 0 by the action of centrifugal force acting on the oil, and the injected oil effectively cools the electromagnet 29. Although the bearing 57 easily receives heat from the electromagnet 29, the oil injected from the tapered bearing 40 is also supplied to the bearing 57, so that the bearing 57 is also effectively cooled and lubricated.

The oil flowing forward from the annular oil passage 69 is also supplied to the bearing 33, and the oil flowing through the passage in the intermediate shaft 24 is supplied to the bearing 37. The hole 70 formed in the front wall 25b and the steel ball 7
Reference numeral 1 denotes a filling port for filling the staying chamber 50 with a viscous fluid, and this filling port is sealed after filling the viscous fluid. FIG.
As shown in the figure, an oil reservoir 72 communicating with the oil passages 64, 67, 69 is formed at the bottom of the differential casing 12, and a drain plug 73 for removing oil from the oil reservoir 72 is screwed into the plug hole 74. At the inner end of the drain plug 73, a permanent magnet that adsorbs iron powder in oil is mounted. The oil reservoir 72 and the drain plug 73 are connected to the differential casing 12 and the unit casing 2.
1 is shared with the first. The annular oil passage 67
An annular shelf 16 extending from the differential casing 12 side is formed on the inner peripheral side of the oil reservoir 72.
Therefore, the foreign matter accumulated in the oil sump 72 easily stays without being stirred by the oil.

Next, a description will be given of a mounting structure of a harness or the like as an external connection for energizing the electromagnet 29 (see FIGS. 3, 7 to 9). The electromagnet 29 is electrically connected to a drive circuit via a harness 80, and the electromagnet 2 is connected via a switch provided on an instrument panel in front of a driver's seat.
9, the electromagnet 29 can also be energized by a control signal from a control device such as an ABS control device. Here, a cutout portion 81 is formed in a part of the yoke 56 of the electromagnet 29, and two connection portions 82 for connecting the coil 55 and the harness 80 are arranged in the cutout portion 81. At positions corresponding to these connection portions 82, a substantially semicircular cutout portion 83 is formed in the spigot fitting portion 35 of the unit casing 21, and the connecting flanges 34 are partially formed on both sides of the cutout portion 83. A notch (not shown) is also formed in the connection flange 14 of the differential casing 12.

The two connecting portions 82 are connected to the semicircular notch 8
3, a sealing member 84 made of a synthetic resin is used as a sealing member for sealing the portion. The sealing member 84 includes a fitting portion 84a that fits into the notch portion 83 in a liquid-tight manner.
And two upper and lower flange portions 84b and two holes 84c through which the two harnesses 80 are inserted in a liquid-tight manner. When the two harnesses 80 are inserted through the two holes 84c of the sealing member 84, and the electromagnet 29 is assembled and fitted into the notch 83 of the sealing member 84 in a tight manner, the flat portion 84d of the sealing member 84 Is aligned with the rear end face of the spigot fitting portion 35, and is completely sealed in a liquid-tight manner when the spigot fitting portion 35 is fitted into the spigot fitting hole 13. In this way, the harness 80 can be led out while maintaining a liquid-tight structure by using the seal fitting 84 having a simple configuration and using the spigot fitting portion.

Next, an air breather 85 common to the differential casing 12 and the unit casing 21 will be described (see FIG. 3). As described above, since the drive pinion 11 having the hypoid gear teeth is arranged so as to be offset below the rear wheel axle 8, a dead space-like depression 86 is formed in the upper and side portions of the front portion of the differential casing 12.
An air breather 85 (air breather device) is disposed in the recess 86 in an upright position and is screwed to the differential casing 12. The air breather 85 prevents the gas pressure inside the differential casing 12 and the unit casing 21 from rising.

Next, the operation and effect of the power transmission device 20 will be described. First, the differential limiting operation will be described. When the rotational speed difference between the front wheel 1 and the rear wheel 7 is less than a predetermined value, the pressure of the viscous fluid in the retaining chamber 50 of the clutch operating mechanism 45 is low, and the piston member 47 does not press the multi-plate clutch 44. The clutch 44 is in a non-engaged state. When the rotational speed difference between the front wheel 1 and the rear wheel 7 exceeds a predetermined value during acceleration or braking of the vehicle, the pressure of the viscous fluid in the stagnation chamber 50 increases according to the rotational speed difference, and the piston member 47 Since the clutch 44 is pressed, the multi-plate clutch 44 is brought into the engaged state according to the rotational speed difference. As a result, the multi-plate clutch 44 can transmit torque according to the rotational speed difference, and the differential between the front wheel 1 and the rear wheel 7 is automatically limited.

The multi-plate clutch 44 is engaged as described above regardless of whether the rotation speed of the front wheel 1 is higher than the rotation speed of the rear wheel 7 (when driven by the intermediate shaft) or lower (when driven by the outer case). You. As a result, slippage of the front wheel 1 during acceleration, locking of the front wheel 1 or the rear wheel 7 during braking, and the like are suppressed,
A stable running state is obtained. However, the operating characteristics of the clutch operating mechanism 45 may be the same or different between when the intermediate shaft is driven and when the outer case is driven. The operating characteristics of the clutch operating mechanism 45 can be freely set by appropriately setting the shape of the blade portion of the rotary blade 51.

When the driver desires to switch to the four-wheel drive state when traveling on a rough road, traveling on an icy road, accelerating, or the like, when the electromagnet 29 is energized through the switch, the The four-wheel drive in which the outer case 25, the intermediate shaft 24, and the drive pinion 11 rotate integrally with each other by the magnetically actuated actuation of the booster operating mechanism 30, by which the multi-plate clutch 44 is switched to the engaged state. State. However, the same applies when the electromagnet 29 is energized by a control signal from a control device such as an ABS control device. As described above, the power transmission device 20 can be switched to the four-wheel drive state according to the driver's intention or control signal, so that the power transmission device 20 is excellent in versatility and suitable for various vehicles. In addition, since the boosting operation mechanism 30 is provided, the size of the electromagnet 29 can be reduced, which is advantageous in manufacturing cost.

Next, the operation and effects of the unit casing 21 and the spigot fitting portion will be described. At the rear end of the unit casing 21 which is more easily thermally expanded than the differential casing 12, a spigot inner fitting portion 35 is formed, and the spigot inner fitting portion 35 is formed at the spigot fitting hole 1 at the front end of the differential casing 12.
3, the oil leakage from the spigot fitting portion can be reliably prevented, and the unit casing 21 can be firmly fixed to the differential casing 12. Further, four mounting portions 32 are provided on the upper surface portion of the unit casing 21 at a sufficient interval in the left-right direction and the front-rear direction, and the four mounting portions 32 are fixed to the vehicle body. Can be mounted on the car body.

Next, the cooling action and the action related to the oil,
The effect will be described. The unit casing 21 is fixed to the front end of the differential casing 12 so that traveling wind can easily hit the unit casing 21, and the unit casing 2
Since a plurality of cooling fins 31 are provided on the outer surface of the power transmission device 1, heat radiation from the unit casing 21 is promoted via the cooling fins 31, the entire power transmission device 20 can be maintained at an appropriate temperature, and the clutch operation can be performed. Variations in the characteristics of the viscous fluid of the mechanism 45 can be prevented, and the operation of the differential limiting clutch mechanism 27 can be stabilized. In addition, since the temperature rise of the oil can be prevented by heat radiation from the unit casing 21, deterioration of the oil is prevented, and
0 and the rear differential 9 can also be improved in durability.

An electromagnet 29 is arranged on the rear end side of the unit casing 21, and the electromagnet 29 is
Since the oil is cooled by directly injecting oil from 0, the temperature of the electromagnet 29 is maintained at substantially the same temperature as the substantially constant oil temperature flowing through the inside of the differential casing 12 and the unit casing 21. , And the durability of the electromagnet 29 can be secured.
In addition, although the oil temperature tends to increase as the rotation speed of the drive pinion 11 increases, the oil injection amount also increases as the rotation speed increases, so that the temperature of the electromagnet 29 can be maintained substantially constant. Then, the sealing device 84 is applied to the structure in which the harness 80 for energizing the electromagnet 29 is introduced into the unit casing 21, and the harness 80 is introduced by fitting the sealing device 84 into the notch 83 of the inner fitting portion 35. The harness 80 can be introduced into the unit casing 21 with a simple structure without impairing the liquid tightness.

The bearing 57 for supporting the yoke 56 of the electromagnet 29 receives heat from the electromagnet 29. Since the bearing 57 is also configured to directly inject oil from the tapered bearing 40 to cool and lubricate the bearing 57, Seizure and reduction in durability can be prevented. Since one common drain plug 73 is provided for the unit casing 21 and the differential casing 12, the number of the drain plugs 73 can be reduced, and permanent magnets are provided on the drain plugs 73 to adsorb iron powder. Can be prevented. In addition, since the upper part of the oil reservoir 72 is covered with the shelf 16, the iron powder and foreign matters accumulated in the oil reservoir 72 are less likely to be stirred by the oil.

Next, the operation and effect of the air breather 85 will be described. Since one common air breather 85 is provided for the unit casing 21 and the differential casing 12, the number of air breathers can be reduced by half, the size of the apparatus can be reduced as a whole, and the production cost is advantageous. The oil circulates through the inside of the unit casing 21 and the inside of the differential casing 12 which is difficult to raise the temperature, and the temperature rise of the oil is also reduced, so that the evaporation amount of the oil is reduced and the air breather 85 can be downsized. .

An air breather 85 is provided at a position close to the electromagnet 29 as a heat source, and the air breather 85 is connected to the oil communication passage 65 via a vertical passage 87. When the pressure rises, the air breather 85 operates quickly, the responsiveness of the air breather 85 can be secured, and the temperature of the electromagnet 29 is also hard to rise. Also,
Since the air breather 85 is attached to the differential casing 12 having a small temperature change, the air breather 8 is
5 can also prevent oil leak from the mounting portion. Also,
Since the air breather 85 is arranged in the recess 86 like a dead space on the upper side of the differential casing 12, it is advantageous in preventing intrusion of muddy water into the air breather 85, and the durability of the air breather 85 can be enhanced.

An example in which the above embodiment is partially changed will be described. 1) Regarding the clutch operating mechanism 45, various structures can be applied as the rotary blade 51, and the rotary blade 51 has two blade portions extending straight in the radial direction, and has a plurality of curved blade portions. Things can be applied. The viscous fluid sealed in the retaining chamber 50 is not limited to silicone oil, and another viscous fluid may be used.

2) The outer peripheral portion of the end case 26 is fixed to the screw hole 25c of the outer case 25 by internal fitting.
In some cases, the position of the end case 26 is finely adjusted via the screw portion, so that the characteristics of the differential limiting clutch mechanism 27 can be finely adjusted. 3) The shapes and structures of the yoke 56 and the end case 26 of the electromagnet 29 are not limited to those shown in the drawings, but may be various shapes and structures as long as they function as electromagnets.

[0046]

According to the first aspect of the present invention, an oil communication passage is formed for communicating the inside of the differential casing with the inside of the unit casing. The oil communication passage is connected to the oil communication passage and reduces the gas pressure in both casings. Since the air breather device for preventing the oil is provided, the oil flows between the inside of the unit casing and the inside of the differential casing through the oil communication passage, so that the temperature of the oil is kept low as a whole and the gas in the unit casing is kept low. The pressure is less likely to rise. In addition, since the air breather device is connected to the oil communication passage that connects the inside of the differential casing and the inside of the unit casing, one relatively small air breather device can be shared between the unit casing and the differential casing. It operates with good responsiveness both when the gas pressure inside the differential casing rises and when the gas pressure inside the differential casing rises.

According to the second aspect of the present invention, since the clutch unit includes an electromagnet and one end of the oil communication passage is open toward the electromagnet, the gas pressure near the electromagnet as a heat source increases. However, since one end of the oil communication passage is open toward the electromagnet, a rise in gas pressure near the electromagnet can be effectively prevented, and a rise in the temperature of the electromagnet can be suppressed.
The other effects are the same as those of the first aspect.

According to the invention of claim 3, the drive pinion of the differential gear mechanism is disposed so as to be offset downward with respect to the axis of the differential gear mechanism, and the air breather device is disposed above the drive pinion. Since the space is provided, a space can be secured above the drive pinion, and the air breather device can be disposed by effectively utilizing the space. The other effects are the same as those of the first or second aspect.

According to the present invention, the drive pinion of the differential gear mechanism is disposed so as to be offset downward with respect to the axis of the differential gear mechanism, and the upper surface of the differential casing is provided above the drive pinion. On the side, a recess is formed that is recessed downward, and the air breather device is disposed in the recess and attached to the differential casing, so that the upper surface of the differential casing is located above the drive pinion, as in claim 3. An air breather can be formed by forming a recess that is recessed downward, and the air breather can be arranged by effectively utilizing the recess like a dead space. The provision is advantageous in preventing oil leak from the air breather device connection due to thermal expansion. The other effects are the same as those of the first or second aspect.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a driving force transmission system of a vehicle according to an embodiment of the present invention.

FIG. 2 is a cross-sectional plan view of a power transmission device and a main part of a rear differential.

FIG. 3 is a partially cutaway longitudinal side view of a power transmission device and a rear differential.

FIG. 4 is a plan view of a unit casing.

FIG. 5 is a side view of the unit casing.

FIG. 6 is a front view of a unit casing.

FIG. 7 is a longitudinal sectional view of a main part such as an electromagnet and a harness.

FIG. 8 is a plan view of the sealing device.

FIG. 9 is a side view of the sealing device.

[Explanation of symbols]

 Reference Signs List 9 rear differential 11 drive pinion 12 differential casing 20 power transmission device 21 unit casing 29 electromagnet 64 oil passage 65 oil communication passage 85 air breather 86 depression

Claims (4)

[Claims] 1. A power transmission device in which a clutch unit is accommodated in a unit casing fixed to a differential casing accommodating a differential gear mechanism of a vehicle, and the clutch unit is oil-lubricated. A power transmission device, comprising: an oil communication passage that communicates with the inside of the unit casing; and an air breather device that is connected to the oil communication passage and that prevents a rise in gas pressure in both casings. 2. The clutch unit includes an electromagnet,
The power transmission device according to claim 1, wherein one end of the oil communication passage opens toward an electromagnet. 3. A drive pinion of the differential gear mechanism is provided so as to be offset downward with respect to an axis of the differential gear mechanism, and an air breather device is provided above the drive pinion. The power transmission device according to claim 1 or 2, wherein 4. A drive pinion of the differential gear mechanism is disposed so as to be offset downward with respect to an axis of the differential gear mechanism, and a recess is formed on an upper surface side of the differential casing above the drive pinion. A depression is formed,
The said air breather apparatus was arrange | positioned in the said recessed part, and was attached to the differential casing.
A power transmission device according to item 1.