JPH10272944A - Transfer structure of four-wheel drive vehicle - Google Patents

Abstract

(57) [Problem] In a transfer structure of a four-wheel drive vehicle, a common transfer case can be used to appropriately take measures against temperature rise in the case, and to cope with the necessity of a breather mechanism. I do. An opening (20h) is provided on the front side of a transfer case (20) for accommodating a transfer shaft (15), a transfer output shaft (18), and a hypoid gear set (16, 17) provided between these two shafts, and the opening is detachable. In the transfer structure of a four-wheel drive vehicle covered with a cover member 50, the cover member includes a radiating fin 51 for lowering the temperature inside the transfer case, and a breather device for preventing the pressure inside the transfer case from rising to a certain level or more. 55, and the breather device is disposed on a side relatively far from the hypoid gear set, and the heat radiation fins are disposed on a side relatively close to the hypoid gear set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a transfer structure for a four-wheel drive vehicle.

[0002]

2. Description of the Related Art Conventionally, in a four-wheel drive vehicle of a type in which a transmission is arranged in series with a horizontally mounted engine, a first axle (for example, a so-called FF) which is arranged in parallel with an output shaft of the transmission and receives driving force. In the case of a vehicle of the type, the driving force is not directly taken out from the front axle (so-called one-shaft type), but a transfer shaft as a kind of intermediate shaft for power transmission is arranged in parallel with the first axle. And a so-called two-shaft type in which power is transmitted to a propeller shaft via the transfer shaft. In the case of this two-shaft type, by setting the vertical position of the transfer shaft to be lower than the first axle by a fixed value or more, the position of the propeller shaft can be suitably lowered. It is possible to avoid such a problem that the airbag protrudes high toward the cabin and adversely affects the livability in the cabin.

In the above-described two-shaft type four-wheel drive vehicle, the driving force of the engine is input to the transfer shaft from the transmission via, for example, a differential device disposed between left and right wheels on the front wheel axle. In order to convert the input driving force into a 90-degree direction and transmit it to the propeller shaft side, the transfer shaft extends in a direction perpendicular to the shaft (that is, in a direction along the axis of the propeller shaft). In general, power transmission between these two shafts is performed using a bevel gear such as a bevel gear or a hypoid gear which is a kind of a torsion bevel gear. Then, a predetermined lubricating oil is filled in the transfer case accommodating the transfer shaft in order to lubricate the meshing portion of the bevel gear and the bearing supporting the transfer shaft and the transfer output shaft.

When the transfer case is filled with lubricating oil and sealed, it is necessary to provide a breather mechanism for preventing the inside of the case from being pressurized above a certain level in order to adjust the pressure difference between the inside and outside of the case. It may be. For example, JP-A-3-288054 (hereinafter referred to as Conventional Technique 1) discloses a transfer case in which a breather mechanism is provided on a side surface of a main body of a transfer case.

[0005] In the two-shaft four-wheel drive vehicle, when assembling a bevel gear type gear set accommodated in a transfer case, generally, the transfer shaft is supported on the case body side of the transmission. Assemble the transfer case supporting the transfer output shaft from the propeller axis direction. However, if the meshing state of the bevel gear set does not accurately define the position in three dimensions, problems such as noise and wear will occur. Therefore, individual manufacturing errors for each part are absorbed by using shims. I am trying to do it. At this time, if the assembly is performed from the propeller axis direction, the tightening torque and shim are accurately controlled and controlled on the joint surface of the case.
It needed to be adjusted.

To simplify this work, for example, as disclosed in Japanese Patent Application Laid-Open No. 8-108760 (hereinafter referred to as prior art 2), a transfer shaft,
It is known that the transfer output shaft and the bevel gear set are assembled to the transfer case, the meshing state of the bevel gear set is adjusted first, and the transfer case is assembled from the side of the case body of the transmission in the adjusted state. Have been. In this case, the transfer unit including the transfer shaft and the transfer output shaft, the bearings that support these shafts, and the power transmission gears and other components provided on the shafts are opened through the opening provided in the transfer case. The sub-assembly is housed therein to form a sub-assembly, and this sub-assembly is connected to the case of the transmission.

[0007]

By the way, the lubricating oil filled in the transfer case rises in temperature due to the rotation of the transfer shaft and the transfer output shaft. There is a fear of coming. In addition, since the transfer case accommodates a transfer shaft to which the driving force of the engine is transmitted via a transmission-side unit including a differential device, for example, the transmission-side unit is reduced in terms of compactness of the power transmission device. Is preferably located as close as possible to As a result, it will be located closer to the engine. For this reason, the temperature inside the transfer case may increase due to the influence of heat from the engine, the temperature of the lubricating oil filled therein may rise, and the lubrication performance may decrease.

For this reason, it is conceivable to provide a cooling means in the transfer case. However, the temperature rise condition in the transfer case is greatly affected by the rotation range of the transfer shaft, the heat radiation condition of the engine, the positional relationship with the engine and the like. These differ depending on the vehicle model. Therefore, if the cooling means is fixedly provided on the case itself, a different transfer case must be prepared for each vehicle type, and there is a problem that it is difficult to use a common transfer case. Also, depending on the type of vehicle, there may or may not be a need to provide a breather mechanism for the transfer case. Is difficult to achieve.

The present invention has been made in view of the above problems, and in a transfer structure of a four-wheel drive vehicle, a common transfer case can be used to appropriately take measures against temperature rise in the case. The basic purpose is to be able to respond to no.

[0010]

Therefore, the invention according to claim 1 of the present application (hereinafter referred to as the first invention) accommodates a transfer shaft to which the driving force of the engine is transmitted via a transmission-side unit. An opening is provided on one side of the transfer case, and the opening is covered with a detachable lid member. In the transfer structure of a four-wheel drive vehicle, the lid member lowers the temperature inside the transfer case. A cooling means is provided.

Further, the invention according to claim 2 of the present application (hereinafter referred to as “the invention”)
The second invention) is characterized in that, in the first invention, the cooling means is constituted by a radiation fin.

Further, the invention according to claim 3 of the present application (hereinafter referred to as “the invention”)
An opening is provided on one side of a transfer case that houses a transfer shaft through which a driving force of an engine is transmitted via a transmission-side unit, and the opening is a detachable lid member. In the transfer structure of a four-wheel drive vehicle to be covered, the cover member is provided with a breather mechanism for preventing the inside of the transfer case from being pressurized above a certain level.

Further, the invention according to claim 4 of the present application (hereinafter, referred to as a fourth invention) is characterized in that a transfer shaft to which the driving force of the engine is transmitted via a transmission-side unit, An opening is provided on one side of a transfer case that accommodates a transfer output shaft extending in the direction and a bevel gear set provided between these two shafts, and the opening is covered with a removable lid member. In the transfer structure of a four-wheel drive vehicle, the cover member is provided with cooling means for lowering the temperature in the transfer case, and a breather mechanism for preventing the inside of the transfer case from being boosted to a certain level or more. The mechanism is arranged relatively far from the bevel gear set, while the cooling means is arranged relatively close to the bevel gear set. A.

Further, the invention according to claim 5 of the present application (hereinafter referred to as “the invention”
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the transfer case includes a transfer shaft provided with an input gear for receiving a driving force transmitted from a transmission-side unit; A transfer unit having a transfer output shaft extending at right angles to the shaft and a bevel gear set provided between the two shafts is pre-assembled from the opening to form a sub-assembly body. A body is assembled to the transmission-side unit.

[0015]

According to the first aspect of the present invention,
The detachable lid member is provided with cooling means for lowering the temperature inside the transfer case, so that the temperature rise conditions in the transfer case such as the rotation range of the transfer shaft, the heat radiation condition of the engine, and the positional relationship with the engine are determined. The difference can be dealt with by changing only the lid member. Therefore, it is possible to use a common transfer case without having to consider the temperature rising conditions in the transfer case.

Further, according to the second aspect of the present invention, basically the same effects as those of the second aspect can be obtained. In particular, since the cooling means is composed of the radiation fins, the structure is simple, and when the lid member is manufactured by a molding process such as casting, the cooling means is easily formed at the time of manufacturing. Can be provided.

Further, according to the third aspect of the present invention, since the breather mechanism is provided on the detachable lid member, the necessity of the breather mechanism is changed by changing only the lid member. be able to. Therefore, it is possible to use a common transfer case without having to consider the necessity of the breather mechanism.

Still further, according to the fourth aspect of the present invention, a cooling means for lowering the temperature inside the transfer case, and a breather mechanism for preventing the inside of the transfer case from being pressurized to a certain level or more are provided on the cover member. When the breather mechanism is provided, since the breather mechanism is disposed relatively far from the bevel gear set and less scattered oil due to its meshing rotation, clogging of the breather mechanism with oil and from the breather mechanism to the outside of the transfer case. Problems such as oil leakage can be effectively prevented. On the other hand, since the cooling means is disposed relatively close to the bevel gear set and in a place where the scattered oil is large, the lubricating oil in the transfer case can be cooled more effectively. That is, the cooling means and the breather mechanism can be appropriately arranged in accordance with the position at which the scattered oil is generated by the meshing rotation of the bevel gear set, and the respective functions can be effectively exerted.

Further, according to the fifth aspect of the present invention, basically, the same effects as any one of the first to fourth aspects can be obtained. In addition, a sub-assembly is constructed by assembling the transfer unit in a transfer case in advance, and is used when assembling the transfer unit in the transfer case in assembling the sub-assembly with the transmission-side unit. The above-mentioned cooling means and / or breather mechanism can be provided by using a lid member that covers the opening.

[0020]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a skeleton diagram schematically illustrating a configuration of a power transmission device for a four-wheel drive vehicle according to the present embodiment. As shown in this figure, the four-wheel drive vehicle is, for example, a so-called FF type in which front wheels (not shown) can be constantly driven by an engine En disposed in a front portion of the vehicle, and is of a horizontal type. The engine En,
The output shaft 1 is arranged in the engine room with the output shaft 1 facing the vehicle width direction. On the output side of this engine En,
For example, an automatic transmission Tm is arranged in series with the engine output shaft 1, and the engine output shaft 1 is connected to a torque converter 3 housed in a case 2 of the transmission Tm.
It is connected to.

The transmission case 2 includes a torque converter housing 2A housing a torque converter 3 and a transmission housing 2B housing a transmission mechanism following the torque converter housing 2A. The torque converter housing 2A is adjacent to the engine En and is formed to have a larger diameter than other parts of the transmission case 2 (the transmission housing 2B and the like) because the torque converter 3 accommodates a large volume of the torque converter 3. And the transmission Tm is the engine En
Are arranged in series in the engine E in plan view.
n overhangs the rear side of the vehicle body.

An output gear 5 of a transmission mechanism is integrally fixed to the output shaft 4 of the transmission Tm, and the output gear 5 constitutes a final reduction portion of the transmission Tm (in other words, the front wheels). A relatively large-diameter first ring gear (final ring gear) 6 (which serves as an input gear for the drive mechanism) meshes. The first ring gear 6 is more preferably fixed to the outer peripheral portion of the front differential 7. In other words, a differential device 7 between the left and right front wheels is disposed on the inner peripheral side of the large-diameter first ring gear 6 by effectively utilizing the inner space thereof, and the difference in which the volume is relatively large is provided. As for the arrangement of the moving devices 7, an efficient layout is realized.

A pair of left and right first axles 8 (front wheel axles) for driving front wheels via the front differential 7.
Extend in the vehicle width direction (that is, in parallel with the transmission output shaft 4). Each front wheel axle 8 is rotatably supported by bearings indicated by reference numerals △ and に お い て in the figure. Also, at the shaft end of each of these front wheel axles 8,
Front wheel drive shafts 9 for driving the front wheels are connected via universal joints 11, respectively. Thus, a so-called FF drive system capable of constantly driving the front wheels is configured, and the transmission T
m from the output shaft 4 is transmitted to the front wheel axle 8 via the output gear 5, the first ring gear 6, and the differential device 7 sequentially, and further transmitted to the front wheel drive shaft 9 via the universal joint 11. It is transmitted to.

Next, a power transmission system for variably controlling the distribution of the driving torque of the rear wheels will be described. A transfer shaft 15 rotatably supported behind the front wheel axle 8 by a predetermined distance is arranged in parallel with the front wheel axle 8. As can be clearly understood from FIG. 2, the transfer shaft 15 is set so that its vertical position is lower than the front wheel axle 8 by a predetermined amount, and accordingly, the driving force is directly transmitted from the front wheel axle. The vertical position of the propeller shaft 21 can be made lower than that of a single-shaft type that takes out the propeller shaft. In the present embodiment, a straight line L connecting the axis of the front wheel axle 8 and the axis of the transfer shaft 15 is shown.
The three shafts 4, 8, 15 are arranged such that the inclination angle β with respect to the horizon of the transmission 2 is larger than the inclination angle α with respect to the horizon of the straight line L1 connecting the axis of the transmission output shaft 4 and the axis of the front wheel axle 8.
Is set.

The transfer shaft 15 has 1
The power is transmitted from the front wheel axle 8 via a pair of gears 13 and 14. That is, the casing 10 of the front differential 7 arranged on the front wheel axle 8
More preferably, a second ring gear 13 is provided integrally with the front / diff case 10 on the outer peripheral portion of the (front / diff case), while the second ring gear 13 is provided on the left end of the transfer shaft 15 in FIG. An input gear 14 is provided which meshes with the input gear. That is, the second ring gear 13 constitutes an output gear for the transfer shaft 15 side.

A bevel gear type output gear 16 composed of, for example, a bevel gear or a hypoid type ring gear (more preferably, a hypoid ring gear in the present embodiment) is located closer to the center of the transfer shaft 15 than the input gear 14. Fixed. The output gear 16 meshes with a pinion gear 17 of a bevel gear type provided at the front end of a transfer output shaft 18 extending in a direction perpendicular to the transfer shaft 15, and the driving force from the transfer shaft 15 is Transfer output shaft 18 converted by 90 degrees
Is transmitted to The output gear 16 is a transfer shaft 15
For example, the pinion gear 17 is more preferably spline-coupled to the transfer output shaft 1.
8 are integrally formed.

The transfer output shaft 18 is connected to a clutch 31 serving as a variable power transmission unit for variably transmitting the power of the transfer output shaft 18 to the rear wheel axle 23, and is connected to one of the working members. 31
The front end side of the propeller shaft 21 is connected to the other working member. The clutch 31 is operated by, for example, hydraulic pressure or electromagnetic suction. In the present embodiment, it is more preferable to control the operation of the clutch 31 according to, for example, the vehicle speed, the selection of a four-wheel drive, the degree of accelerator opening, and the like. Thereby, in addition to the front wheels, the rear wheels can be actively controlled.

As is well known, in a hypoid type gear set (a combination of the hypoid ring gear 16 and the hypoid pinion gear 17), the respective rotation center axes of the ring gear 16 and the pinion gear 17 are offset. Therefore, the vertical position of the rotating shaft (transfer output shaft 18) of the hypoid pinion gear 17 can be lowered by this offset amount, whereby the vertical position of the central axis of the propeller shaft 21 can be reduced to a predetermined size corresponding to the offset amount. Only the transfer axis 15 can be set lower than the central axis. That is, the propeller shaft 21
The height (therefore, the height of the floor tunnel that covers the upper side of the floor tunnel toward the passenger compartment) can be further reduced.

The transfer shaft 15 and the transfer output shaft 18, bearings for respectively supporting these shafts 15, 18, and a power transmission gear 1 provided on each shaft.
A transfer unit Tf is formed of 4, 16, 17 and the like.
A clutch case 30 containing the clutch 31 is fastened and fixed to the rear end of the transfer case 0. The front end side of the transfer case 20 is fastened and fixed to a part of the transmission case 2 (specifically, a rear part of the torque converter housing 2A). The details of the structure of the transfer case 20 and the configuration and layout of the transfer unit Tf will be described later.

Then, a driving force is transmitted from the propeller shaft 21 to a pair of left and right second axles 23 (rear wheel axles) via a rear differential 22, and the driving forces are transmitted through the universal joints 24. The left and right rear wheel drive shafts 25 respectively connected to the rear wheel axle 23 are rotationally driven.
That is, a gear shaft 27s of a rear pinion gear 27 made of, for example, a bevel gear or a hypoid gear (more preferably, a hypoid gear) is connected to the rear end side of the propeller shaft 21. Reference numeral 27 orthogonally meshes with a rear ring gear 26 fixed to the outer peripheral portion of the rear differential device 22. As a result, the driving force from the propeller shaft 21 becomes 90
The angle is converted and transmitted to the left and right rear axles 23.

Next, the structure of the transfer case 20 and the configuration / layout of the transfer unit Tf, assembling method, and the like will be described mainly with reference to FIGS. In the present embodiment, the front end side of the transfer case 20 is connected to the rear part of the torque converter housing 2A as described above, but as shown in FIG. The front differential 7 is incorporated and housed therein, and is partially open in the direction along the axis of the propeller shaft 21 (that is, rearward).
The first ring gear 6 and the second ring gear 13 project rearward. The first and second ring gears 6 and 13 are formed integrally, and are fastened and fixed to the case body of the front differential 7 by a plurality of bolt members Bt1.

On the other hand, the transfer case 20 is composed of a base portion 41 for inserting and housing the transfer shaft 15 and a cylindrical portion 42 for inserting and housing the transfer output shaft 18 extending in a direction perpendicular to the transfer shaft 15. An opening 2 is provided on the front side (upper side in FIG. 5).
0h is formed, and the opening 20h is covered with the lid member 50. The cover member 50 is provided with a plurality of bolt members Bt4.
To the transfer case 20. The configuration of the lid member 50 will be described later.

In this embodiment, the transfer shaft 1
Reference numeral 5 denotes three bearings J1 and J for the transfer case 20.
2 and J3 are rotatably supported via the bearings J1 and J3.
An input gear 14 for receiving a driving force is integrally provided on one end side (leftward in FIGS. 5 and 6) from the position supported by J2 and J3, and a driving force is applied to the transfer output shaft 18 in the middle thereof. Is mounted. The output gear 16 is arranged near the center bearing J2 of the three bearings J1, J2, J3.

That is, the base 41 of the transfer case 20 is provided with an annular shaft support 41a for mounting the cylindrical roller bearing J1 at the end (left side in FIGS. 5 and 6) on which the torque converter housing 2A is mounted. At the same time, semicircular support portions 41b and 41c for assembling the tapered roller bearings J2 and J3 are provided in order toward the inside of the case 20 (the right side in FIGS. 5 and 6). These two tapered roller bearings J2,
J3 is set on the shaft supporting portions 41b and 41c, and then fitted with a cap member 43 having a semicircular inner peripheral portion, and tightening the bolt member Bt5, whereby the shaft supporting portion 41 is set.
b, 41c. The rotation of the transfer output shaft 18 is supported by two tapered roller bearings J4 and J5.

In this embodiment, the output gear 1
6 and the bearings J2, J3 are actually fixed to a hollow member 35 described below. That is, in the present embodiment, a hollow member 35 having a predetermined length is arranged on the outer peripheral side of the transfer shaft 15. The hollow member 35 cannot rotate with respect to the transfer shaft 15 by, for example, spline fitting. The inner races of the tapered roller bearings J2 and J3 are press-fitted into both ends of the hollow member 35, and the hollow member 35 is mounted on the two tapered roller bearings J.
2, and is rotatably supported by the transfer case 20 via J3. The hypoid type output gear 16 for transmitting the driving force to the transfer output shaft is assembled in the middle of the hollow member 35, and the tapered roller bearings J2 and J3 are located on both sides thereof. In addition, the output gear 16 is arrange | positioned close to the center bearing J2 as mentioned above.

Furthermore, shims Cm2 to Cm4 for adjusting the tooth contact of the hypoid gear sets 16, 17 are arranged outside the tapered roller bearings J2, J3, respectively. Tapered roller bearing J at the shaft end of the transfer shaft 15
The shim Cm4 arranged outside the inner ring of No. 3 is formed by a nut member 44 fastened to the shaft end of the transfer shaft 15.
It is pressed and fixed to the inner ring side of the tapered roller bearing J3. The shaft end of the transfer shaft 15 to which the nut member 44 is fastened is covered by a cover member 45. An adjustment shim Cm1 is interposed between the back surface of the hypoid gear 17 (pinion gear) formed integrally with the transfer output shaft 18 and the end surface of the inner ring of the tapered roller bearing J4.

In the present embodiment, the lubricating oil used differs between the transfer unit Tf including the hypoid gear sets 16 and 17 and the meshing portion thereof and the transmission Tm to which the transfer unit Tf is assembled. I have. That is, the transmission oil used for the transmission Tm is not only a function as a lubricating oil for the sliding portion and the meshing portion of the internal mechanism, but also a hydraulic oil for generating a hydraulic pressure for driving an operating component such as a valve spool. Therefore, a material having a relatively low viscosity is selected. On the other hand, regarding the lubricating oil used for the transfer unit Tf,
The hypoid gears 16 and 1 for which high load resistance is required
For lubrication of 7, a high viscosity oil is used.

When the transfer unit Tf is assembled on the transmission Tm side, the internal space of the transfer unit Tf including the meshing portions of the hypoid gear sets 16 and 17 is separated from the space on the transmission Tm side. In order to achieve a liquid-tight seal, a seal member S1 is mounted between the inner peripheral portion of the transfer case 20 and the outer peripheral portion of the transfer shaft 15. In this embodiment, two bearings J1 and J2 are located between the input gear 14 of the transfer shaft 15 and the hypoid type output gear 16, and the seal member S1 is located between these bearings J1 and J2. Are located. A drain port 34 closed by a plug 33 is provided on the side of the transfer case 20 so that it can be used for oil drain when replacing the lubricating oil in the case 20. Is

In this embodiment, as described above,
An opening 20h is formed on the front side (the upper side in FIGS. 5 and 6) of the transfer case 20, and the opening 20h is formed.
Is covered with a lid member 50 detachably attached by bolt members Bt4. The lid member 50 is provided with a plurality of radiating fins 51 as cooling means for lowering the temperature inside the transfer case 20. I have. As shown in detail in FIG.
0 is integrally formed on the surface side. In the present embodiment, the lid member 50 is formed by casting a light alloy such as an aluminum alloy, for example, and the radiation fins 51 are integrally formed during the casting. As can be clearly understood from FIG. 9, the peripheral portion on the bottom side of the lid member 50 includes
Flange 5 for connection to transfer case 20 side
0f is formed, and a bolt member B
A number of bolt insertion holes 50h for inserting t4 are provided.

Further, in order to adjust the pressure difference between the inside and outside of the transfer case 20, the cover member 50 is provided with a breather device 55 for preventing the inside of the transfer case 20 from being pressurized above a certain level. The lid member 50 is formed in a substantially rectangular shape in plan view, and near one corner thereof,
A convex breather chamber 56 protruding toward the front surface is provided. As can be clearly understood from FIG.
A screw hole 57 for screwing and fixing the breather device 55 is provided in the side wall portion of. Since the breather device 55 is the same as a conventionally well-known device, a detailed description of its internal structure, operation, and the like will be omitted.

In the vicinity of the breather chamber 56, an oil suppressing plate 60 (indicated by a two-dot chain line in FIG. 8 and FIG. 10) for suppressing splashed oil from entering the breather chamber 56 is fastened and fixed. Screw holes 58 are provided. The restraining plate 60 is disposed so as to cover most of the lower part of the breather chamber 56 except for the end, and is fastened using a bolt member 59 with a predetermined gap Y provided at the end of the breather chamber 56. Fixed.

In this embodiment, when the cover member 50 is assembled to the transfer case 20, the breather device 55 is located at a position relatively far from the output gear 16, as can be clearly understood from FIGS. The breather device 55 and the radiation fin 51 are positioned so that the radiation fin 51 as the cooling means is located relatively close to the output gear 16.
Are provided for the lid member 50. At this time, the gap Y between the oil suppression plate 60 and the wall of the breather chamber 56 is located at a position farthest from the output gear 16.

In the above configuration, a method of assembling the transfer unit Tf to the transfer case 20 and a method of assembling the transfer case 20 to the torque converter housing 2A will be described below.
explain. In the present embodiment, the transfer shaft 15, the transfer output shaft 18, the hypoid gear set 16, 1
After assembling the transfer unit Tf including the components such as 7 into the transfer case 20 in advance to form the sub-assembly body As, the sub-assembly body is assembled to the torque converter housing 2A side.

This assembling is performed in the following procedure. First, a pair of bearings J supporting the transfer output shaft 18 with respect to the cylindrical portion 42 of the transfer case 20.
4, J5 (tapered roller bearing) is assembled, and a standard model (not shown) of the transfer output shaft 18 is inserted to apply a preload to the bearing J4. In this state, the transfer shaft 15
By measuring the distance between the axial center position of the bearing and the inner ring end face of the bearing J4, the inner ring end face of the bearing J4 and the pinion gear 17 are measured.
The thickness of the shim CM1 (first shim) to be interposed between the back side and the back side is set. A plurality of shims CM1 having different thicknesses are prepared, and the one having the thickness closest to the set value is selected from among them. After setting the thickness of the first shim CM1 in this manner, the standard model (not shown) is extracted, and the selected first shim CM1 is mounted on the transfer output shaft 18 to be actually incorporated. This is inserted into the cylindrical portion 42 of the transfer case 20 and incorporated. Then, the companion flange 19 is fastened and fixed to the shaft end of the transfer output shaft 18 using the nut 39. In the present embodiment, the transfer case 20
Since the opening 20h is provided on the front surface side, the work of inserting the transfer output shaft 18 and its standard model (not shown) into and out of the cylindrical portion 42 can be performed extremely easily.

Next, the output gear 16 is non-rotatably mounted to a predetermined portion in the middle of the hollow member 35 (a portion close to the mounting position of the left tapered roller bearing J2 in the drawing), for example, by spline fitting. Thereafter, the tapered roller bearings J2, J
Press-fit and fix the inner ring No. 3. The step of fixing the output gear 16 and the inner rings of the tapered roller bearings J2 and J3 to the outer peripheral side of the hollow member 35 may be performed prior to or in parallel with the above-described steps. And tapered roller bearings J2, J
In addition to combining the outer ring with the inner ring of No. 3 and setting the second shim Cm2 and the third shim Cm3 outside each of the outer ring of the tapered roller bearings J2 and J3, the tapered roller bearing J
The hollow member 35 is set on the base portion 41 such that 2, 2 and J3 are held in the shaft supporting portions 41b and 41c of the base portion 41 of the transfer case 20. At this time, the axial position of the output gear 16 is preliminarily (to some extent) defined by the second shim Cm2 and the third shim Cm3. Also in this case, the work of setting the hollow member 35 and the components attached thereto into the transfer case 20 is performed by the opening 20h on the front side of the transfer case 20.
Can be easily performed.

In this state, a tooth contact inspection (preliminary inspection) of the hypoid gear set (a combination of the output gear 16 and the pinion gear 17) is performed. When the tooth contact is not good, the thickness of the second and third shims Cm2 and Cm3, specifically, for example, those having an appropriate thickness for the second shim Cm2 are selected and replaced. The axial position is preliminarily defined, and the tooth contact with the pinion gear 17 is readjusted. That is, the tooth contact inspection of the hypoid gear sets 16 and 17 can be performed without assembling the transfer shaft 15. In addition, the readjustment operation when the inspection is rejected is easy before the transfer shaft 15 is assembled.

In a case where a good tooth contact is obtained in the preliminary inspection, the cylindrical roller bearing J1 is mounted on the shaft support 41a of the base 41 of the transfer case 20, and the shaft support 41a supporting the cylindrical roller bearing J1 is provided.
The seal member S1 is mounted in a ring groove positioned between the tapered roller bearing J2 and 41b supporting the tapered roller bearing J2. Further, a fourth shim Cm4 mounted outside the inner ring of the tapered roller bearing J2 is set on the transfer shaft 15. Above, this transfer shaft 15 is non-rotatably assembled from the outside of the transfer case 20 (left side in FIGS. 5 and 6) to the inner peripheral side of the hollow member 35 by, for example, spline fitting.
The mounting work of the cylindrical roller bearing J1 and the seal member S1 may be performed in advance.

Thereafter, a fifth shim Cm5 arranged outside the inner ring of the bearing J3 is set on the outer peripheral portion on the shaft end side of the transfer shaft 15, and a nut member 44 is screwed onto the shaft end of the transfer shaft 15. And tighten it with the specified torque.
Thus, the axial position of the output gear 16 is finally determined, and a predetermined axial load (preload) is applied to the tapered roller bearings J2 and J3. Then, in this state, a tooth contact inspection (final confirmation inspection) of the hypoid gear set (a combination of the output gear 16 and the pinion gear 17) is performed. If the final tooth contact inspection fails, for example, the fourth shim CM4 is replaced with one having a different thickness and reassembled to obtain an appropriate tooth contact.

If the final tooth contact inspection has passed, the shaft support portions 41 of the tapered roller bearings J2 and J3
Each cap member 43 is combined with b and 41c, and each cap member 43 is fastened and fixed by tightening the bolt member Bt5. This completes the incorporation of the transfer unit Tf including the components such as the transfer shaft 15, the transfer output shaft 18, and the hypoid gear sets 16, 17 into the transfer case 20.

Thereafter, a cover member 45 that covers the outer side of the transfer shaft 15 on the terminal side is attached to the transfer case 20 on the side surface of the transfer case 20. The opening 2 on the front side of the transfer case 20
The cover member 50 is set at 0h, and fastened and fixed with the bolt member Bt4. Thus, the assembly of the sub-assembly body As is completed.

The sub-assembly As
To the torque converter housing 2A from the side. This assembling operation is performed by inserting the sub-assembly body As from the side while adjusting the meshing state between the input gear 14 and the second ring gear 13. Then, as shown in FIGS. 2, 3, 4 and 7,
By tightening a plurality of (for example, four) bolt members Bt3, the sub-assembly body As is fixed to the torque converter housing 2A. At this time, both positions are set so that the transfer shaft 15 does not cross the rotation surface of the final ring gear 6 (first ring gear).

As described above, according to the present embodiment, more preferably, the transfer gear 15 is provided with the input gear 14 at one end outside of the support position of the three bearings J1 to J3, whereby the transfer shaft 15 is provided. The support structure of the shaft 15 is so-called cantilever support with respect to the load input point.
It is extremely easy to set the positions of the final ring gear 6 (the first ring gear) so that they do not cross the rotating surface of the final ring gear 6, and the diameter of the final ring gear 6 is not limited by the existence of the transfer shaft 15. Even when the distance between the output shaft 4 of the transmission Tm and the front wheel axle 8 is determined, the degree of freedom in setting the reduction ratio between the output gear 5 of the transmission Tm and the final ring gear 6 can be greatly increased. it can. And in this case,
A hypoid-type output gear 16 that transmits the driving force of the engine En to a transfer output shaft 18 includes three bearings J1.
To J3, the radial displacement of the output gear 16 can be effectively restricted, and the hypoid gear set (a combination of the output gear 16 and the pinion gear 17) can be used. The change in tooth contact can be reduced. That is, while maintaining the effect of the transfer shaft 15 having the cantilever support structure, the noise in the hypoid gear sets 16 and 17 can be reduced, and the life of the gear can be improved.

After assembling the transfer unit Tf to the transfer case 20 in advance to form the sub-assembly body As, the sub-assembly body As is assembled to the transmission Tm side (specifically, the torque converter housing 2A). Therefore, the workability of assembling the transfer unit Tf can be improved. Moreover, in this case, a hollow member 35 having a predetermined length is provided on the outer peripheral side of the transfer shaft 15 so as to be non-rotatable with respect to the transfer shaft 15.
Are rotatably supported on the transfer case 20 via bearings J2 and J3,
The transfer output shaft 1 is provided in the middle of the hollow member 35.
Since the output gear 16 for transmitting the driving force to the drive gear 8 is mounted, the tooth contact inspection of the hypoid gear sets 16 and 17 can be performed without assembling the transfer shaft 15. Therefore, the tooth contact inspection itself can be easily performed, and a readjustment operation can be easily performed when the tooth contact inspection fails.

In particular, since the bearings J2 and J3 supporting both ends of the hollow member 35 or the vicinity thereof are tapered roller bearings having high axial rigidity, the hypoid type output gear 16 attached to the hollow member 35 is used. Can be defined more accurately.

Further, the tapered roller bearings J2, J3
Since the shims Cm2 to Cm5 for adjusting the tooth contact of the hypoid gear sets 16 and 17 are arranged outside the shaft, the axial position of the hypoid type output gear 16 can be more accurately defined.

Further, with respect to the transfer shaft 15 whose rotation is supported by the three bearings J 1 to J 3, two bearings J 1 are provided between the output gear 16 for transmitting the driving force to the transfer output shaft 18 and the input gear 14. , J2 in which the radial displacement of the transfer shaft 15 is strongly restricted.
1 and J2, the input gear 1 communicating with the transmission Tm side.
Since the seal member S1 that seals the space on the fourth side and the space on the side of the output gear 16 of the hypoid type in a liquid-tight manner is disposed, the deformation of the seal member S1 when the transfer shaft 15 rotates while receiving the transfer load is effectively suppressed. It is possible,
The life of the seal member S1 can be further improved.

Further, according to the present embodiment, since the cooling means (radiation fins 51) for lowering the temperature in the transfer case 20 is provided in the detachable lid member 50, the rotation range of the transfer shaft 15 is provided. Differences in the temperature rise conditions in the transfer case 20, such as the heat radiation conditions of the engine En and the positional relationship with the engine En, can be dealt with by changing only the lid member 50. Therefore, it is possible to share the transfer case 20 without having to consider the temperature rising condition in the transfer case 20.

In particular, since the cooling means is constituted by the radiation fins 51, the structure is simple, and
Since the cooling means 51 is manufactured by casting, the cooling means 51 can be easily formed integrally during the manufacturing.

Further, since the breather device 55 is provided on the removable lid member 50, the necessity of the breather device 55 can be dealt with by changing only the lid member 50. Therefore, the transfer case 20 can be shared without having to consider the necessity of the breather device 55.

Further, a cooling means 51 for lowering the temperature inside the transfer case 20 is provided on the lid member 50.
(Radiation fins) and a breather device 55 for preventing the inside of the transfer case 20 from being pressurized above a certain level. The breather device 55 is disposed relatively far from the hypoid gear sets 16 and 17 by the cooling means 51. Are disposed relatively close to the hypoid gear sets 16 and 17, respectively. That is, the breather device 55
Are located relatively far from the hypoid gear sets 16 and 17 and have less scattered oil due to their meshing rotation, so that oil from the breather device 55 to the outside of the transfer case 20 and clogging of the breather device 55 can be prevented. Failures can be effectively prevented. In particular, the lower part of the breather chamber 56 is largely covered with an oil suppressing plate 60, and the gap Y between the oil suppressor 60 and the wall of the breather chamber 56 is located at a position farthest from the hypoid gear sets 16 and 17. Therefore, it is possible to more effectively prevent the oil from scattering into the breather chamber 56. On the other hand, the cooling means 51 (radiation fins) are relatively close to the hypoid gear sets 16 and 17 and are arranged in a place where the scattered oil is large, so that the lubricating oil in the transfer case 20 can be cooled more effectively. Can be. That is, the cooling means 51 (radiation fins) and the breather device 55 can be appropriately arranged in accordance with the position where the scattered oil is generated due to the meshing rotation of the hypoid gear sets 16 and 17, and the respective functions are effectively exhibited. Can be done.

According to the present embodiment, the transfer unit Tf is previously assembled to the transfer case 20 to form a sub-assembly As, and this sub-assembly As is assembled to the transmission Tm. Opening 20 used when assembling transfer unit Tf into transfer case 20
The cooling means 51 (radiation fins) and the breather device 55 can be provided using the lid member 50 covering the h.

Although the above embodiment has been described with reference to a case where the present invention is applied to a vehicle having an automatic transmission, the present invention is not limited to such a case.
Even when the transmission is a manual transmission type, it can be effectively applied. In addition, the present invention is not limited to the above embodiments, and without departing from the gist thereof,
It goes without saying that various improvements, modifications or changes in design are possible.

[Brief description of the drawings]

FIG. 1 is a skeleton diagram schematically showing a configuration of a power transmission device for a four-wheel drive vehicle according to an embodiment of the present invention.

FIG. 2 is an explanatory side view of the power transmission device.

FIG. 3 is an explanatory sectional view taken along line III-III in FIG. 2;

FIG. 4 is an explanatory sectional view taken along line IV-IV in FIG. 2;

FIG. 5 is an explanatory cross-sectional view showing a transfer structure of the four-wheel drive vehicle according to the embodiment.

FIG. 6 is an explanatory cross-sectional view showing an enlarged main part of a transfer structure of the four-wheel drive vehicle.

FIG. 7 is an explanatory side view of a transfer structure of the four-wheel drive vehicle.

FIG. 8 is an explanatory cross-sectional view of a lid member of a transfer case.

FIG. 9 is an explanatory bottom view of the lid member.

FIG. 10 is an explanatory sectional view taken along line XX in FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 15 ... Transfer shaft 16 ... Transfer shaft output gear 17 ... Pinion gear 18 ... Transfer output shaft 20 ... Transfer case 20h ... Opening part 50 ... Lid member 51 ... Heat radiating fin (cooling means) 55 ... Breezer device As ... Sub-assembly body En ... Engine Tf: Transfer unit Tm: Transmission

Continued on the front page (72) Inventor Hiroaki Hayashi 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd.

Claims (5)

[Claims] An opening is provided on one side of a transfer case that houses a transfer shaft to which a driving force of an engine is transmitted via a transmission-side unit, and the opening is covered with a removable lid member. In the transfer structure for a four-wheel drive vehicle, the cover member is provided with cooling means for lowering the temperature inside the transfer case.
Transfer structure for wheel drive vehicles. 2. The transfer structure for a four-wheel drive vehicle according to claim 1, wherein said cooling means is constituted by a radiation fin. 3. An opening is provided on one side of a transfer case for accommodating a transfer shaft to which a driving force of an engine is transmitted via a transmission-side unit, and the opening is covered with a removable lid member. The transfer structure for a four-wheel drive vehicle according to claim 1, wherein the cover member is provided with a breather mechanism for preventing the inside of the transfer case from being pressurized above a certain level. 4. A transfer shaft to which engine driving force is transmitted via a transmission-side unit, a transfer output shaft extending in a direction perpendicular to the shaft, and a bevel gear set provided between these two shafts. An opening is provided on one side of the transfer case for accommodating the transfer case, and the opening is covered with a detachable lid member. And a breather mechanism for preventing the inside of the transfer case from being boosted to a certain level or more. The breather mechanism is disposed relatively far from the bevel gear set, while the cooling means is provided. A transfer structure for a four-wheel drive vehicle, wherein the transfer structure is disposed relatively close to the bevel gear set. 5. A transfer shaft provided with an input gear for receiving a driving force transmitted from a transmission-side unit, a transfer output shaft extending in a direction perpendicular to the transfer shaft, and both transfer shafts. A transfer unit having a bevel gear set provided therebetween is assembled in advance from the opening to form a sub-assembly body, and the sub-assembly body is assembled to the transmission-side unit. 1 to Claim 4
The transfer structure of a four-wheel drive vehicle according to any one of the above.